Patent Application
20150104460
The present invention relates to antibodies, particularly human natural antibodies recombinant antibodies derived therefrom and fragments thereof, which are capable of binding to and recognizing neurons in the CNS and eliciting responses in CNS neurons. These antibodies are useful in the diagnosis and treatment of conditions associated with nerve damage, injury or degeneration, neurodegenerative disease, chronic nerve injury or damage and sudden nerve injury or damage. The antibodies, variable regions or CDR domain sequences thereof, and fragments thereof of the present invention may also be used in therapy in combination with chemotherapeutics, immune modulators, or neuroactive agents and/or with other antibodies or fragments thereof. This invention relates particularly to methods for alleviating or treating stroke or ischemia, particularly cerebral ischemia, and associated agents, constructs and compositions for use in stroke or ischemia.
Neuroregeneration refers to the regrowth or repair of nervous tissues, cells or cell products. Such mechanisms may include remyelination, generation of new neurons, glia, axons, myelin, or synapses. Neuroregeneration differs between the Peripheral Nervous System (PNS) and the Central Nervous System (CNS) by both the functional mechanisms involved in and the extent and speed of regeneration.
Axon regeneration in the mature mammalian central nervous system (CNS) is very limited after injury. Consequently, functional deficits persist after spinal cord injury (SCI), traumatic brain injury, stroke, and related conditions that involve axonal disconnection. This situation differs from that in the mammalian peripheral nervous system (PNS), where long-distance axon regeneration and substantial functional recovery can occur in the adult. Both extracellular molecules and the intrinsic growth capacity of the neuron influence regenerative success.
Central nervous system (CNS) axons do not spontaneously regenerate after injury in adult mammals. In contrast, peripheral nervous system (PNS) axons readily regenerate, allowing recovery of function after peripheral nerve damage. Aguayo and colleagues demonstrated that at least some mature CNS neurons retain the capacity to regenerate when provided with a permissive peripheral nerve graft (Richardson P M, McGuinness U M, Aguayo A J (1980) Nature 284:264-265; Richardson P M, Issa V M, Aguayo A J (1984) J Neurocytol 13:165-182; David S, Aguayo A J (1981) Science 214:931-933; Benfey M, Aguayo A J (1982) Nature 296:150-152). This work suggested that the PNS environment is stimulatory and/or that the CNS environment is inhibitory for axon growth. Subsequent studies identified both growth-promoting factors in the PNS and growth-inhibiting factors in the CNS. Inhibitors of regeneration include specific proteins in CNS myelin and molecules associated with the astroglial scar. In addition, slower debris clearance in the CNS relative to the PNS may impede axonal re-growth. An understanding of factors which influence axon growth is critical for the development of therapeutics to promote CNS regeneration.
After peripheral nerve injury, axons readily regenerate. The distal portion of the axon, which is disconnected from the cell body, undergoes Wallerian degeneration. This active process results in fragmentation and disintegration of the axon. Debris is removed by glial cells, predominantly macrophages. Proximal axons can then regenerate and re-innervate their targets, allowing recovery of function.
The two major classes of CNS regeneration inhibitors are the myelin-associated inhibitors (MAIs) and the chondroitin sulfate proteoglycans (CSPGs). These molecules limit axon regeneration, and, by interfering with their function, some degree of growth in the adult CNS is achieved. Cell-autonomous factors are also important determinants of CNS regeneration failure. CNS neurons do not upregulate growth-associated genes to the same extent as do PNS neurons. Consequently, their ability to regenerate is limited even in the absence of inhibitors. Increasing the intrinsic growth capacity of neurons allows modest axon regeneration within the CNS (Bomze H M et al (2001) Nat Neurosci 4:38-43; Neumann S, Woolf C J (1999) Neuron 23:83-91).
MAIs are proteins expressed by oligodendrocytes as components of CNS myelin. MAIs impair neurite outgrowth in vitro and are thought to limit axon growth in vivo after CNS damage. MAIs include Nogo-A (Chen M S et al (2000) Nature 403:434-439; GrandPre T et al (2000) Nature 403:439-44), myelin-associated glycoprotein (MAG) (McKerracher L et al (1994) Neuron 13:805-811), oligodendrocyte myelin glycoprotein (OMgp) (Kottis V et al (2002) J Neurochem 82:1566-1569), ephrin-B3 (Benson M D et al (2005) Proc Nat Acad Sci USA 102:10694-10699) and Semaphorin 4D (Sema4D) (Moreau-Fauvarque C et al (2003) J Neurosci 23:9229-9239). Three of these (Nogo-A, MAG and OMgp) interact with a neuronal Nogo-66 receptor 1 (NgR1) to limit axon growth. These three structurally unrelated ligands also show affinity for a second axon growth-inhibiting receptor, paired immunoglobulin-like receptor B (PirB) (Atwal J K et al (2008) Science 322:967-970).
Several recognition molecules which act as molecular cues underlying promotion and/or inhibition of neurite growth have been identified. Among the neurite outgrowth promoting recognition molecules, the neural cell adhesion molecule L1 plays a prominent role in mediating neurite outgrowth (Schachner M (1990) Seminars in the Neurosciences 2:497-507). L1-dependent neurite outgrowth is mediated by homophilic interaction. L1 enhances neurite outgrowth on L1 expressing neurites and Schwann cells, and L1 transfected fibroblasts (Bixby et al (1982) Proc Natl Acad. Sci. U.S.A. 84:2555-2559; Chang et al (1987) J Cell Biol 104:355-362; Lagenaur et al. (1987) Proc Natl Acad Sci USA 84:7753-7757; Seilheimer et al (1988) J Cell Biol 107:341-351; Kadmon et al (1990) J Cell Biol 110:193-208; Williams et al (1992) J Cell Biol 119:883-892).
Nervous system injuries affect over 90,000 people every year, and a much greater number when cerebro-vascular events such as stroke are included. It is estimated that spinal cord injuries alone affect 10,000 each year. As a result of this high incidence of neurological injuries, nerve regeneration and repair, a subfield of neural tissue engineering, is becoming a rapidly growing field dedicated to the discovery of new ways to recover nerve functionality after injury. The nervous system is divided into two parts: the central nervous system, which consists of the brain and spinal cord, and the peripheral nervous system, which consists of cranial and spinal nerves along with their associated ganglia. While the peripheral nervous system has an intrinsic ability for repair and regeneration, the central nervous system is, comparably and for the most part, restricted in its ability to self-repair and regeneration. There is currently no accepted and approved treatment for recovering human nerve function after injury to the central nervous system.
Axon protection and repair following spinal cord injury (SCI) holds great potential as an effective strategy to prevent motor neuron loss and permanent disability. Neuron protection has been achieved using targeted trophic factors for preventing damage and promoting repair of axons following injury. These molecules were predominantly identified using selection strategies based upon in vitro systems that focused upon targeting specific small molecule neurotrophic factors. Whereas these molecules demonstrated neuroprotective results in preclinical models, the results from clinical trials have been less favorable.
Natural autoreactive monoclonal antibodies have demonstrated beneficial biological functions in CNS cells using multiple models of injury and disease. Antibody-mediated promotion of neuron survival, axon regeneration and functional recovery has been demonstrated in vivo using the mouse monoclonal IgM, IN-1 (Bregman B S et al (1995) Nature 378(6556):498-501; Caroni P, Schwab M E (1988) Neuron 1(1):85-96). Similar results were obtained using immunization of spinal cord homogenate (SCH) prior to CNS damage (Ellezam B, Bertrand J, Dergham P, McKerracher L (2003) Neurobiol Dis 12(1):1-10; Huang D W et al (1999) Neuron 24(3):639-647).
Multiple sclerosis (MS) is a chronic, frequently progressive, inflammatory central nervous system (CNS) disease characterized pathologically by primary demyelination, usually without initial axonal injury. The etiology and pathogenesis of MS are unknown. Several immunological features of MS, and its moderate association with certain major histocompatibility complex alleles, have prompted the speculation that MS is an immune-mediated disease. An autoimmune hypothesis is supported by the experimental autoimmune (allergic) encephalomyelitis (EAE) model, where injection of certain myelin components into genetically susceptible animals leads to T cell-mediated CNS demyelination. However, specific autoantigens and pathogenic myelin-reactive T cells have not been definitively identified in the CNS of MS patients, nor is MS associated with other autoimmune diseases. An alternative hypothesis, based upon epidemiological data, is that an environmental factor, perhaps an unidentified virus, precipitates an inflammatory response in the CNS, which leads to either direct or indirect (“bystander”) myelin destruction, potentially with an induced autoimmune component. This hypothesis is supported by evidence that several naturally occurring viral infections, both in humans and animals, can cause demyelination. One commonly utilized experimental viral model is induced by Theiler's murine encephalomyelitis virus (TMEV) (Dal Canto, M. C., and Lipton, H. L., Am. J. Path., 88:497-500 (1977)).
In the case of MS, demyelination ultimately results in nerve cell death. However, axon death following demyelination is not immediate. If appropriate support molecules or cells are provided the nervous system has a significant capacity for repair. Protecting axons of the CNS promises to be an effective strategy to limit the loss of surviving axons and prevent permanent disability. Neuroprotection may be achieved by modulating the potentially neurotoxic inflammatory environment in lesions. Reagents designed to limit excitotoxicity, inhibit nitric oxide, or block ion channels are under study as methods to protect axons in danger (Pitt, D., P. Werner, and C. S. Raine (2000) Nat Med 6:67-70; Okuda, Y et al (1997) Journal of neuroimmunology 73:107-116; Waxman, S. G. (2002). J Rehabil Res Dev 39:233-242). Many of these reagents are small molecules with demonstrated toxicity and act systemically on all cells.
Ischemia is a restriction in blood supply to tissues, causing a shortage of oxygen and glucose needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems with blood vessels, with resultant damage to or dysfunction of tissue. It also refers to local anemia in a given part of a body sometimes resulting from congestion (such as vasoconstriction, thrombosis or embolism). Hypoxia is a condition in which the body as a whole or a region of the body (tissue hypoxia, or less commonly regional hypoxia) is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise. A mismatch between oxygen supply and its demand at the cellular level may result in a hypoxic condition. Ischemic hypoxia occurs when there is decreased blood flow and can occur for example in heart failure and vasodilatory shock. Cerebral hypoxia occurs when there is not enough oxygen getting to the brain. The brain needs a constant supply of oxygen and nutrients to function.
In cerebral hypoxia, sometimes only the oxygen supply is interrupted. This can be caused by smoke inhalation), carbon monoxide poisoning, choking, diseases that prevent movement of the breathing muscles, high altitudes, pressure on the windpipe (trachea), and strangulation. In other cases, both oxygen and nutrient supply are stopped or interrupted, such as in cardiac arrest, cardiac arrhythmia, complications of general anesthesia, drowning, drug overdose, injuries to a newborn during or after birth such as in cerebral palsy, stroke, very low blood pressure.
Brain ischemia is insufficient blood flow to the brain, and can be acute or chronic. Acute ischemic stroke is a neurologic emergency that may be reversible if treated rapidly. Chronic ischemia of the brain may result in a form of dementia called vascular dementia. A brief episode of ischemia affecting the brain is called a Transient Ischemic Attack (TIA), frequently referred to as a mini-stroke.
A stroke, also known as a cerebrovascular accident (CVA), is the rapid loss of brain function(s) due to disturbance in the blood supply to the brain. This can be due to ischemia (lack of blood flow) caused by blockage (thrombosis, arterial embolism), or a hemorrhage (leakage of blood). Brain ischemia, also known as cerebral ischemia, is a condition in which there is insufficient blood flow to the brain to meet metabolic demand and is a type of stroke along with subarachnoid hemorrhage and intracerebral hemorrhage. Ischemia may be focal ischemia, which is confined to a specific region of the brain, or global ischemia, which encompasses wide areas of brain tissue. Stroke is the leading cause of long-term disability in the United States. Each year, close to 800,000 people suffer a stroke. Following ischemic injury, the disability associated with clinical deficits is primarily due to dysfunction of neurons. The lack of functional recovery is in part attributed to the restriction of regeneration and neuroplasticity (Walmsley, A. R., and Mir, A. K. (2007) Current pharmaceutical design 13:2470-2484). Stroke may result in a altered motor function such as an inability to move one or more limbs on one side of the body, cognitive effects such as an inability to understand or formulate speech, or other deficits including visual effects such as an inability to see one side of the visual field. There are currently no effective treatments to prevent or reverse stroke-related neurologic deficits.
An ischemic stroke is occasionally treated in a hospital with thrombolysis (also known as a “clot buster”), and some hemorrhagic strokes benefit from neurosurgery. Prevention of recurrence can involve the administration of antiplatelet drugs such as aspirin and dipyridamole, control and reduction of hypertension, and the use of statins. Selected patients may benefit from carotid endarterectomy and the use of anticoagulants. Interventional therapy of cerebral ischemia remains limited to enzymatic thrombolysis by use of recombinant tissue plasminogen activator rtPA (Brott, T. G., et al (1992) Stroke 23:632-640; Haley, E. C., et al (1992) Stroke 23:641-645; Group, T. N. (1995) New England J Med 333:1581-1587), and to interventional removal of the blood clot via direct catheterization (Gobin Y P et al (2004) Stroke 35:2848-2854). However, rtPA has a short 3 hr therapeutic window and increased incidence of hemorrhagic cerebral ischemia if infused beyond the 3 hr time frame (Clark, W M et al (1999) JAMA 282:2019-2026; Hacke W et al (2008) New England J Med 359:1317-1329).
Human monoclonal autoantibodies have been identified that exhibit activity in the central nervous system, and that were particularly associated with the stimulation of remyelination. It would be desirable to develop human monoclonal antibodies with activity in the CNS, particularly recombinant antibodies with these activities, and with capability to promote neural regeneration and/or to protect neurons from disease, injury, damage and/or death particularly in instances of stroke or brain/cerebral ischemia, or where oxygen or blood flow to the brain or CNS is deprived or affected either acutely or chronically. In particular, use and application of human monoclonal antibodies, with capability to access the CNS and treat, prevent or alleviate cerebral ischemia or stroke would be desirable. It is toward the achievement of that objective that the present invention is directed.
The citation of references herein shall not be construed as an admission that such is prior art to the present invention.
The invention relates to neuromodulatory agents with particular effectiveness in the CNS, which agents comprise a material selected from the group consisting of an antibody of the IgM subtype, active fragments thereof, monomers thereof, agonists thereof and combinations thereof. The neuromodulatory agents or antibodies of the invention have one or more of the following characteristics: they protect and/or stabilize neurons; they target sites in the CNS or nerve cell damage, compromise or injury; they reduce or block cell death, e.g. hydrogen-peroxide induced cell death. In a particular aspect of the present invention the agents, particularly neuron-binding monoclonal antibodies are effective and have application and use in treating and alleviating stroke and ischemia, particularly cerebral ischemia, and in conditions where ischemia or hypoxia of nerve cells or the brain is involved or has occurred.
The invention provides neuron-binding monoclonal antibodies with capability to promote neurite extension, to act in neuroregeneration, and/or to protect neurons from damage and for diagnostic and therapeutic purposes in the central nervous system. The present studies demonstrate that when neuron-binding monoclonal antibodies, particularly antibody IgM12 rHIgM12, are administered to animals following stroke (in this instance an animal model for induction of ischemic stroke), it results in a clear improvement of function of the animals and protects tissue integrity.
In particular, specific recombinant antibodies are provided, wherein said antibodies recognize and are capable of binding neurons, including cortical neurons, hippocampal neurons, cerebellar granule cells and retinal ganglion cells, and which target and mediate neurons and neural cells in the event and upon a stroke, ischemic condition, or ischemia or hypoxia in nerve cells or microglia. Recombinant fully human antibodies are provided herein. The antibodies of the present invention have diagnostic and therapeutic use in conditions or diseases associated with nerve compromise, damage or injury.
In a general aspect, the present invention provides antibodies directed against and capable of binding one or more epitope on neurons, including cortical neurons, hippocampal neurons, cerebellar granule cells and retinal ganglion cells. In a broad aspect, the present invention provides an isolated specific binding member, particularly an antibody or fragment thereof, including a recombinant human antibody, which recognizes, binds, and/or targets neurons. The invention provides an antibody, particularly a human antibody, particularly an IgM antibody, which specifically binds neurons and protects neurons from cell death and which does not promote remyelination. The antibody of the invention has use in treating or ameliorating diseases or conditions in mammals where nerves are compromised, injured or damaged or are at risk thereof, including in spinal cord injury (SCI), traumatic brain injury (TBI), Amyolotropic Lateral Sclerosis (ALS), multiple sclerosis (MS), Alzheimer's disease, stroke, Parkinson's disease, Huntington's disease, prenatal anoxia/perinatal ischemia, Cerebral Palsy, encephalopathy, myelopathy, or motor neuron diseases, and particularly in the protection, survival or maintenance of neurons and neurological capacity in these diseases.
In a particular aspect, the antibody of the invention or compositions thereof have use and application in stroke and in cerebral ischemia. In a particular aspect, the antibodies or compositions of the invention have use in conditions in which there is insufficient blood flow and/or oxygen to the brain to meet metabolic demand or wherein there is traumatic injury to the brain resulting in death or injury or risk of death or injury of neurons and associated cells. In a particular aspect, the present invention provides an antibody or fragment thereof, which is antibody 12 or 42, particularly serum derived or recombinant IgM12 or IgM42.
In an aspect of the invention a recombinant or synthetic neuron binding antibody is provided comprising the variable region CDR sequences set out in
The invention thus provides isolated human IgM antibody(ies) or fragment(s) thereof which specifically binds neurons and protects neurons from cell death and which does not promote remyelination, wherein the antibody or fragment comprises: (a) the variable heavy chain amino acid CDR domain sequences CDR1 GGSVSLYY (SEQ ID NO:31), CDR2 GYIYSSGST (SEQ ID NO:32) and CDR3 ARSASIRGWFD (SEQ ID NO:33), and light chain CDR sequences CDR1 QSISSY (SEQ ID NO: 34), CDR2 AAS (SEQ ID NO:35) and CDR3 QQSYHTPW (SEQ ID NO:36), as set out in
In a further particular aspect, the antibody of the invention comprises the amino acid sequence of antibody 12 or 42 including as set out in
In a further aspect, the present invention provides an isolated antibody or fragment thereof capable of binding an antigen, wherein said antibody or fragment thereof comprises a polypeptide binding domain comprising an amino acid sequence substantially as set out herein and in
In a further aspect, the present invention provides an isolated fully human antibody or fragment thereof capable of binding an antigen, wherein said antibody or fragment thereof comprises a polypeptide binding domain comprising an amino acid sequence substantially as set out herein and in
In further aspects, the invention provides an isolated nucleic acid which comprises a sequence encoding a neuron binding polypeptide or antibody as defined above, and methods of preparing polypeptides or antibodies of the invention which comprise expressing said nucleic acids under conditions to bring about expression of said polypeptide or antibody, and recovering the polypeptide or antibody. In one such aspect, a nucleic acid encoding antibody variable region sequence having the amino acid sequences as set out in
The antibodies, fragments thereof and recombinant antibodies comprising the variable region sequences according to the invention may be used in a method of treatment, prevention or diagnosis of the human or animal body, such as a method of neuroprotection in a mammal which comprises administering to said mammal an effective amount of the antibodies, fragments thereof and recombinant antibodies of the invention. Recombinant antibodies or fragments thereof comprising the CDR domain region sequences according to the invention may be used in a method of neuroprotection in a mammal which comprises administering to said mammal an effective amount of the antibodies, fragments thereof and recombinant antibodies of the invention.
The agents of the invention, particularly recombinant antibodies or fragments thereof may be used as neuroprotective agents in methods for prevention, treatment or amelioration of nerve injury, damage or compromise and complications that can, may or do result in CNS damage. The treatment or prevention methods of the invention are applicable where loss of structure, function or survival of neurons is involved or associated including brain injury or trauma, spinal cord injury (SCI), nerve injury, head injury, conditions where blood supply to the brain is reduced or compromised, infectious diseases of the brain, neurodegenerative diseases. Exemplary such diseases or conditions for treatment, prevention or amelioration in accordance with the methods of the invention include spinal cord injury (SCI), traumatic brain injury (TBI), Amyolotropic Lateral Sclerosis (ALS), multiple sclerosis (MS), Alzheimer's disease, stroke, Parkinson's disease, Huntington's disease, prenatal anoxia/perinatal ischemia and/or Cerebral Palsy, encephalopathy, myelopathy, and motor neuron diseases. The present invention thus relates to methods of treating or ameliorating diseases or conditions in mammals where nerves are compromised, injured or damaged or scenarios where nerves or neurons are susceptible or at risk of compromise, injury or damage comprising administering a recombinant antibody or fully human antibody or fragment thereof selected from IgM12 and IgM42.
In a particular aspect of the invention, the antibodies, fragments thereof and recombinant antibodies comprising the variable region sequences according to the invention, may be utilized in methods or administered in compositions for treatment or amelioration of stroke or cerebral ischemia. In a particular aspect of the invention, the antibodies, fragments thereof and recombinant antibodies comprising the variable region sequences according to the invention, may be utilized in methods or administered in compositions for treatment or amelioration of stroke. In a particular aspect of the invention, the antibodies, fragments thereof and recombinant antibodies comprising the variable region sequences according to the invention, may be utilized in methods or administered in compositions for treatment or amelioration of cerebral ischemia. In an embodiment of the invention, the antibodies, fragments thereof and recombinant antibodies comprising the variable region sequences according to the invention, may be utilized in methods or administered in compositions for improving motor function in conditions such as stroke. The antibodies, fragments thereof and recombinant antibodies comprising the variable region sequences according to the invention, may be utilized in methods or administered in compositions for improving motor function in an animal suffering from or suspected of suffering from a stroke. The antibodies, fragments thereof and recombinant antibodies comprising the variable region sequences according to the invention, may be utilized in methods or administered in compositions for improving motor function in an animal that has had a stroke or that has cerebral ischemia. In a particular aspect, IgM12, rIgM12, antibody 12 comprising heavy chain CDR sequences CDR1 GGSVSLYY (SEQ ID NO:31), CDR2 GYIYSSGST (SEQ ID NO:32) and CDR3 ARSASIRGWFD (SEQ ID NO:33), and light chain CDR sequences CDR1 QSISSY (SEQ ID NO: 34), CDR2 MS (SEQ ID NO:35) and CDR3 QQSYHTPW (SEQ ID NO:36), as set out in
In an aspect of the invention, the antibodies, fragments thereof and recombinant antibodies comprising the variable region sequences according to the invention, may be utilized in methods or administered in compositions for improvement or stabilization of neurological function or of motor function in instances, diseases or conditions wherein nerves are compromised, injured or damaged or scenarios where nerves or neurons are susceptible or at risk of compromise, injury or damage. In a particular aspect, the antibodies or fragments thereof are utilized or administered in early or initial stages of a disease, trauma, or condition, or repeated over the course or duration of a disease, trauma, or condition, so as to facilitate or maintain the improvement or stabilization of neurological function or motor function, including or selected from movement, such as walking, or cognitive function, such as recall or recognition.
In an aspect of the invention, the antibodies, fragments thereof and recombinant antibodies comprising the variable region sequences according to the invention, may be utilized in methods or administered in compositions for mitigating or ameliorating neurological effects, defects, damage or neuronal cell death in the event of a stroke or cerebral ischemia. In accordance with the methods, the antibody(ies) ameliorate one or more functional or assessable neurological or motor parameter, including an evaluable or scalable parameter such as a stroke scale or function scale. Administration of the antibody(ies) is effective to improve or ameliorate one or more of a symptom or parameter associated with stroke, including for example one or more of upper and lower extremity motor function, limb ataxia, sensory function, language, articulation, attention, gaze and visual function, arm, hand and leg power and movement.
Methods of the invention may comprise administration of more than one antibody or fragment, including combinations of antibody IgM12 and 42. In an aspect of the invention, methods are provided comprising administering one or more antibody or fragment thereof, wherein an antibody comprises (a) the variable heavy chain amino acid CDR domain sequences CDR1 GGSVSLYY (SEQ ID NO:31), CDR2 GYIYSSGST (SEQ ID NO:32) and CDR3 ARSASIRGWFD (SEQ ID NO:33), and light chain CDR sequences CDR1 QSISSY (SEQ ID NO: 34), CDR2 AAS (SEQ ID NO:35) and CDR3 QQSYHTPW (SEQ ID NO:36) or (b) the variable heavy chain amino acid CDR domain sequences CDR1 GFTFSTYA (SEQ ID NO: 37), CDR2 INVGGVTT (SEQ ID NO:38) and CDR3 VRRSGPDRNSSPADF (SEQ ID NO:39), and light chain CDR sequences CDR1 QGIG (SEQ ID NO: 40), CDR2 TTS (SEQ ID NO:41) and CDR3 QKYNSAPRT (SEQ ID NO: 42). In a further such method, one or more of antibody IgM12 and/or of antibody IgM42 may be combined with another CNS active antibody, particularly including one or more of antibodies rHIgM22 and/or rHIgM46. rHIgM22 antibody comprises the amino acid sequence set forth in SEQ ID NO: 43 and 44, or the CDRs of these SEQ IDs. rHIgM46 antibody comprises the amino acid sequence set forth in SEQ ID NO: 45 and 46, or the CDRs of these SEQ IDs. Thus, one or more of antibody IgM12 and/or of antibody IgM42 may be combined with one or more remyelinating antibody comprising (a) heavy chain variable region CDRs comprising CDR1 sequence SSGMH CDR2 sequence V(I)ISYDGSRKYYADSVKG and CDR3 sequence GVTGSPTLDY, and light chain variable region CDRs comprising CDR1 sequence SGSSSNIGNNFVS CDR2 sequence DITKRPS and CDR3 sequence G(E)TWDSSLSAV V; or (b) heavy chain variable region CDRs comprising CDR1 sequence SGFTFSSYW CDR2 sequence IKKDGSEK and CDR3 sequence ARPNCGGDCYLPWYFD, and light chain variable region CDRs comprising CDR1 sequence QSVLYSSNNKNY CDR2 sequence YWAS and CDR3 sequence QQYYNTPQA. Combinations of antibodies may be administered collectively or in series, and at various times and various amounts or concentrations. Bi- or multi-specific antibodies may be utilized. In a particular such aspect, antibody 12 and/or 42 is administered in combination with antibody 22 and/or 46 and/or an antibody having the CDR region CDR1, CDR2 and CDR3 sequences of IgM22 or IgM46, by combined administration or in series, separated by a short length of time or longer length of time, including by hours, days or weeks. In one such particular aspect antibody 12 and/or 42 is administered in combination with antibody 22 and/or 46, by combined administration or in series for the treatment of amelioration of a disease or condition involving neurodegeneration, and particularly including demyelination. In a further such aspect antibody 12 and/or 42 is administered in combination with antibody 22 and/or 46, by combined administration or in series for the treatment of amelioration of a demyelinating disease or condition. In a particular aspect, antibody 12 and/or 42 is administered in combination with antibody 22 and/or 46, by combined administration or in series for the treatment of amelioration of multiple sclerosis. In one such aspect, remyelination and neuroprotection is achieved for combined effects, including synergistic effects, on a measurable clinical aspect of MS disease.
In view of the neuroprotective and/or neuroregenerative capabilities of the agents of the invention, this invention further relates to in vitro methods of producing and stimulating the proliferation of neurons, including the proliferation of cortical neurons, hippocampal neurons, cerebellar granule cells and retinal ganglion cells. Such proliferated neurons may be suitable for transplantation and nerve cell therapeutic protocols and methods.
The diagnostic utility of the present invention extends to the use of the antibodies of the present invention in assays and methods to characterize CNS nerve injury or damage or to screen for or assess disease or conditions involving nerve injury, damage or death (including necrotic or apoptotic death), including in vitro and in vivo diagnostic and imaging assays. Thus, the antibodies may be utilized in assays and methods to assess stroke or ischemia and/or to evaluate injury in following ischemia or stroke or predicted or suspected ischemia or stroke. In an immunoassay, a control quantity of the antibodies, or the like may be prepared and labeled with an enzyme, a specific binding partner, ligand, a dye, a fluorescent tag and/or a radioactive element, and may then be introduced into a cellular sample. After the labeled material or its binding partner(s) has had an opportunity to react with sites within the sample, the resulting mass may be examined by known techniques, which may vary with the nature of the label attached. In an in vivo diagnostic or imaging application, the antibody or a neuron binding fragment thereof may be prepared and labeled with an enzyme, a specific binding partner, ligand, a dye, a fluorescent tag and/or a radioactive element, and may then be introduced into a an animal. After the labeled material or its binding partner(s) has had an opportunity to react with sites within the animal, the animal may be examined by known techniques, which may vary with the nature of the label attached. In an aspect of the diagnostic utility of the invention, the antibodies or active fragments thereof of the invention may be utilized in assays and methods to characterize cerebral ischemia or stroke. In particular, in instances where cerebral ischemia or stroke is suspected or at risk, the antibodies of the invention may be utilized to determine or assess for cerebral ischemia and/or stroke.
The radiolabelled specific binding members, particularly antibodies and fragments thereof, are useful in in vitro diagnostics techniques and in in vivo radioimaging techniques. In a further aspect of the invention, radiolabelled specific binding members, particularly antibodies and fragments thereof, particularly radioimmunoconjugates, are useful in radioimmunotherapy, particularly as radiolabelled antibodies for nerve injury repair, neuroregeneration, neurodegenerative recovery, cancer or CNS tumor therapy, or alternatively for ablation of damaged nerve tissue or neurons in certain instances. In an in vivo aspect, the antibody or neuron binding fragment thereof is labeled and administered to the animal prior to, during or after surgery or a surgical technique, including a stereotactic or minimally invasive technique, for the purpose of locating nerve injury or for assessing remaining damaged or injured neural tissue. In one such aspect, the radiolabelled specific binding members, particularly antibodies and fragments thereof, are useful in radioimmuno-guided surgery techniques, wherein they can identify and indicate the presence and/or location of compromised, damaged, injured or dying nerve cells or neurons or nervous tissue, prior to, during or following surgery to target, identify or remove such cells.
Immunoconjugates or antibody fusion proteins are included in the present invention, wherein the specific binding members, particularly antibodies and fragments thereof, of the present invention are conjugated or attached to other molecules or agents further include, but are not limited to binding members conjugated to a neuroactive drug, chemical ablation agent, toxin, immunomodulator, cytokine, cytotoxic agent, chemotherapeutic agent or drug.
The present invention includes an assay system which may be prepared in the form of a test kit for the quantitative analysis of the extent of the presence of, for instance, damaged, compromised or injured neurons or to quantitate neurons in a sample. The system or test kit may comprise a labeled component prepared by one of the radioactive and/or enzymatic techniques discussed herein, coupling a label to the antibody, and one or more additional immunochemical reagents, optionally at least one of which is a free or immobilized component(s) or their binding partner(s).
The antibodies of the present invention, and in a particular embodiment recombinant antibody(ies) comprising the heavy and/or light chain sequences presented in
The present invention also includes antibodies and fragments thereof, which are covalently attached to or otherwise associated with other molecules or agents. These other molecules or agents include, but are not limited to, molecules (including antibodies or antibody fragments) with distinct recognition characteristics, toxins, ligands, neuroactive agents, and chemotherapeutic agents. In an additional aspect the antibodies or fragments of the invention may be used to target or direct therapeutic molecules or other agents, for example to target molecules or agents to neurons, for example to cortical neurons, hippocampal neurons, retinal ganglion cells or cerebellar granule cells, including at wound sites, ischemic sites, tumor sites, inflammatory areas or neurodegenerative lesions. The antibodies or fragments of the invention may be used to target or direct therapeutic molecules or other agents, for example to target molecules or agents to sites of cerebral ischemia or stroke.
Other objects and advantages will become apparent to those skilled in the art from a review of the ensuing detailed description, which proceeds with reference to the following illustrative drawings, and the attendant claims.
In accordance with the present invention there may be employed conventional molecular biology, microbiology, and recombinant DNA techniques within the skill of the art. Such techniques are explained fully in the literature. See, e.g., Sambrook et al, “Molecular Cloning: A Laboratory Manual” (1989); “Current Protocols in Molecular Biology” Volumes I-III [Ausubel, R. M., ed. (1994)]; “Cell Biology: A Laboratory Handbook” Volumes I-III [J. E. Celis, ed. (1994))]; “Current Protocols in Immunology” Volumes i-III [Coligan, J. E., ed. (1994)]; “Oligonucleotide Synthesis” (M. J. Gait ed. 1984); “Nucleic Acid Hybridization” [B. D. Hames & S. J. Higgins eds. (1985)]; “Transcription And Translation” [B. D. Hames & S. J. Higgins, eds. (1984)]; “Animal Cell Culture” [R. I. Freshney, ed. (1986)]; “Immobilized Cells And Enzymes” [IRL Press, (1986)]; B. Perbal, “A Practical Guide To Molecular Cloning” (1984).
Therefore, if appearing herein, the following terms shall have the definitions set out below.
The term “specific binding member” describes a member of a pair of molecules which have binding specificity for one another. The members of a specific binding pair may be naturally derived or wholly or partially synthetically produced. One member of the pair of molecules has an area on its surface, or a cavity, or a component on its surface, which specifically binds to and is therefore complementary to a particular spatial and polar organization of the other member of the pair of molecules. Thus the members of the pair have the property of binding specifically to each other. Examples of types of specific binding pairs are antigen-antibody, biotin-avidin, hormone-hormone receptor, receptor-ligand, enzyme-substrate. This application is concerned with antigen-antibody type reactions.
The term “antibody” describes an immunoglobulin whether natural or partly or wholly synthetically produced. The term also covers any polypeptide or protein having a binding domain which is, or is homologous to, an antibody binding domain. CDR grafted antibodies are also contemplated by this term. An “antibody” is any immunoglobulin, including antibodies and fragments thereof, that binds a specific epitope. The term encompasses polyclonal, monoclonal, and chimeric antibodies, the last mentioned described in further detail in U.S. Pat. Nos. 4,816,397 and 4,816,567. The term “antibody(ies)” includes a wild type immunoglobulin (Ig) molecule, generally comprising four full length polypeptide chains, two heavy (H) chains and two light (L) chains, or an equivalent Ig homologue thereof (e.g., a camelid nanobody, which comprises only a heavy chain); including full length functional mutants, variants, or derivatives thereof, which retain the essential epitope binding features of an Ig molecule, and including dual specific, bispecific, multispecific, and dual variable domain antibodies; Immunoglobulin molecules can be of any class (e.g., IgG, IgE, IgM, IgD, IgA, and IgY), or subclass (e.g., IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2). Also included within the meaning of the term “antibody” are any “antibody fragment”.
An “antibody fragment” means a molecule comprising at least one polypeptide chain that is not full length, including (i) a Fab fragment, which is a monovalent fragment consisting of the variable light (VL), variable heavy (VH), constant light (CL) and constant heavy 1 (CH1) domains; (ii) a F(ab′)2 fragment, which is a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) a heavy chain portion of an Fab (Fd) fragment, which consists of the VH and CH1 domains; (iv) a variable fragment (Fv) fragment, which consists of the VL and VH domains of a single arm of an antibody, (v) a domain antibody (dAb) fragment, which comprises a single variable domain (Ward, E. S. et al., Nature 341, 544-546 (1989)); (vi) a camelid antibody; (vii) an isolated complementarity determining region (CDR); (viii) a Single Chain Fv Fragment wherein a VH domain and a VL domain are linked by a peptide linker which allows the two domains to associate to form an antigen binding site (Bird et al, Science, 242, 423-426, 1988; Huston et al, PNAS USA, 85, 5879-5883, 1988); (ix) a diabody, which is a bivalent, bispecific antibody in which VH and VL domains are expressed on a single polypeptide chain, but using a linker that is too short to allow for pairing between the two domains on the same chain, thereby forcing the domains to pair with the complementarity domains of another chain and creating two antigen binding sites (WO94/13804; P. Holliger et al Proc. Natl. Acad. Sci. USA 90 6444-6448, (1993)); and (x) a linear antibody, which comprises a pair of tandem Fv segments (VH-CH1-VH-CH1) which, together with complementarity light chain polypeptides, form a pair of antigen binding regions; (xi) multivalent antibody fragments (scFv dimers, trimers and/or tetramers (Power and Hudson, J Immunol. Methods 242: 193-204 9 (2000)); and (xii) other non-full length portions of heavy and/or light chains, or mutants, variants, or derivatives thereof, alone or in any combination.
As antibodies can be modified in a number of ways, the term “antibody” should be construed as covering any specific binding member or substance having a binding domain with the required specificity. Thus, this term covers antibody fragments, derivatives, functional equivalents and homologues of antibodies, including any polypeptide comprising an immunoglobulin binding domain, whether natural or wholly or partially synthetic. Chimeric molecules comprising an immunoglobulin binding domain, or equivalent, fused to another polypeptide are therefore included. Cloning and expression of chimeric antibodies are described in EP-A-0120694 and EP-A-0125023 and U.S. Pat. Nos. 4,816,397 and 4,816,567.
An “antibody combining site” is that structural portion of an antibody molecule comprised of light chain or heavy and light chain variable and hypervariable regions that specifically binds antigen.
The phrase “antibody molecule” in its various grammatical forms as used herein contemplates both an intact immunoglobulin molecule and an immunologically active portion of an immunoglobulin molecule.
Exemplary antibody molecules are intact immunoglobulin molecules, substantially intact immunoglobulin molecules and those portions of an immunoglobulin molecule that contains the paratope, including those portions known in the art as Fab, Fab′, F(ab′)2 and F(v), which portions are preferred for use in the therapeutic methods described herein.
Antibodies may also be bispecific, wherein one binding domain of the antibody is a specific binding member of the invention, and the other binding domain has a different specificity, e.g. to recruit an effector function or the like. Bispecific antibodies of the present invention include wherein one binding domain of the antibody is a specific binding member of the present invention, including a fragment thereof, and the other binding domain is a distinct antibody or fragment thereof, including that of a distinct anti-cancer or anti-tumor specific antibody. The other binding domain may be an antibody that recognizes or targets a particular cell type, as in a neural or glial cell-specific antibody. In the bispecific antibodies of the present invention the one binding domain of the antibody of the invention may be combined with other binding domains or molecules which recognize particular cell receptors and/or modulate cells in a particular fashion, as for instance an immune modulator (e.g., interleukin(s)), a growth modulator or cytokine (e.g. tumor necrosis factor (TNF), and particularly, the TNF bispecific modality demonstrated in U.S. Ser. No. 60/355,838 filed Feb. 13, 2002 incorporated herein in its entirety) or a toxin (e.g., ricin) or anti-mitotic or apoptotic agent or factor. Thus, the anti-FAP antibodies of the invention may be utilized to direct or target agents, labels, other molecules or compounds or antibodies to stromal sites, particular areas of wound healing, inflammation, cancer or tumors.
The phrase “monoclonal antibody” in its various grammatical forms refers to an antibody having only one species of antibody combining site capable of immunoreacting with a particular antigen. A monoclonal antibody thus typically displays a single binding affinity for any antigen with which it immunoreacts. A monoclonal antibody may also contain an antibody molecule having a plurality of antibody combining sites, each immunospecific for a different antigen; e.g., a bispecific (chimeric) monoclonal antibody.
The term “antigen binding domain” describes the part of an antibody which comprises the area which specifically binds to and is complementary to part or all of an antigen. Where an antigen is large, an antibody may bind to a particular part of the antigen only, which part is termed an epitope. An antigen binding domain may be provided by one or more antibody variable domains. Preferably, an antigen binding domain comprises an antibody light chain variable region (VL) and an antibody heavy chain variable region (VH).
Immunoconjugates or antibody fusion proteins of the present invention, wherein the antibodies, antibody molecules, or fragments thereof, of use in the present invention are conjugated or attached to other molecules or agents further include, but are not limited to such antibodies, molecules, or fragments conjugated to a chemical ablation agent, toxin, immunomodulator, cytokine, cytotoxic agent, chemotherapeutic agent, antimicrobial agent or peptide, cell wall and/or cell membrane disrupter, or drug.
The term “specific” may be used to refer to the situation in which one member of a specific binding pair will not show any significant binding to molecules other than its specific binding partner(s). The term is also applicable where e.g. an antigen binding domain is specific for a particular epitope which is carried by a number of antigens, in which case the specific binding member carrying the antigen binding domain will be able to bind to the various antigens carrying the epitope.
The term “comprise” generally used in the sense of include, that is to say permitting the presence of one or more features or components.
The term “consisting essentially of” refers to a product, particularly a peptide sequence, of a defined number of residues which is not covalently attached to a larger product. In the case of the peptide of the invention referred to above, those of skill in the art will appreciate that minor modifications to the N- or C-terminal of the peptide may however be contemplated, such as the chemical modification of the terminal to add a protecting group or the like, e.g. the amidation of the C-terminus.
The term “isolated” refers to the state in which specific binding members of the invention, or nucleic acid encoding such binding members will be, in accordance with the present invention. Members and nucleic acid will be free or substantially free of material with which they are naturally associated such as other polypeptides or nucleic acids with which they are found in their natural environment, or the environment in which they are prepared (e.g. cell culture) when such preparation is by recombinant DNA technology practiced in vitro or in vivo. Members and nucleic acid may be formulated with diluents or adjuvants and still for practical purposes be isolated—for example the members will normally be mixed with gelatin or other carriers if used to coat microtitre plates for use in immunoassays, or will be mixed with pharmaceutically acceptable carriers or diluents when used in diagnosis or therapy.
As used herein, “pg” means picogram, “ng” means nanogram, “ug” or “μg” mean microgram, “mg” means milligram, “ul” or “μl” mean microliter, “ml” means milliliter, “l” means liter.
The terms “antibody”, “neuron binding antibody”, “IgM12 antibody”, “IgM42 antibody”, “antibody 12”, “antibody 42”, “sHIgM12”, “sHIgM42”, “rHIgM12”, “rHIgM42” and any variants not specifically listed, may be used herein, and as used throughout the present application and claims refer to proteinaceous material including single or multiple proteins, and extends to those proteins having the amino acid sequence data described herein and presented in
The amino acid residues described herein are preferred to be in the “L” isomeric form. However, residues in the “D” isomeric form can be substituted for any L-amino acid residue, as long as the desired functional property of immunoglobulin-binding is retained by the polypeptide. NH2 refers to the free amino group present at the amino terminus of a polypeptide. COOH refers to the free carboxy group present at the carboxy terminus of a polypeptide. In keeping with standard polypeptide nomenclature, J. Biol. Chem., 243:3552-59 (1969), abbreviations for amino acid residues are shown in the following
Table of Correspondence:
It should be noted that all amino-acid residue sequences are represented herein by formulae whose left and right orientation is in the conventional direction of amino-terminus to carboxy-terminus. Furthermore, it should be noted that a dash at the beginning or end of an amino acid residue sequence indicates a peptide bond to a further sequence of one or more amino-acid residues. The above Table is presented to correlate the three-letter and one-letter notations which may appear alternately herein.
A “replicon” is any genetic element (e.g., plasmid, chromosome, virus) that functions as an autonomous unit of DNA replication in vivo; i.e., capable of replication under its own control.
A “vector” is a replicon, such as plasmid, phage or cosmid, to which another DNA segment may be attached so as to bring about the replication of the attached segment.
A “DNA molecule” refers to the polymeric form of deoxyribonucleotides (adenine, guanine, thymine, or cytosine) in its either single stranded form, or a double-stranded helix. This term refers only to the primary and secondary structure of the molecule, and does not limit it to any particular tertiary forms. Thus, this term includes double-stranded DNA found, inter alia, in linear DNA molecules (e.g., restriction fragments), viruses, plasmids, and chromosomes. In discussing the structure of particular double-stranded DNA molecules, sequences may be described herein according to the normal convention of giving only the sequence in the 5′ to 3′ direction along the nontranscribed strand of DNA (i.e., the strand having a sequence homologous to the mRNA).
An “origin of replication” refers to those DNA sequences that participate in DNA synthesis.
A DNA “coding sequence” is a double-stranded DNA sequence which is transcribed and translated into a polypeptide in vivo when placed under the control of appropriate regulatory sequences. The boundaries of the coding sequence are determined by a start codon at the 5′ (amino) terminus and a translation stop codon at the 3′ (carboxyl) terminus. A coding sequence can include, but is not limited to, prokaryotic sequences, cDNA from eukaryotic mRNA, genomic DNA sequences from eukaryotic (e.g., mammalian) DNA, and even synthetic DNA sequences. A polyadenylation signal and transcription termination sequence will usually be located 3′ to the coding sequence.
Transcriptional and translational control sequences are DNA regulatory sequences, such as promoters, enhancers, polyadenylation signals, terminators, and the like, that provide for the expression of a coding sequence in a host cell.
A “promoter sequence” is a DNA regulatory region capable of binding RNA polymerase in a cell and initiating transcription of a downstream (3′ direction) coding sequence. For purposes of defining the present invention, the promoter sequence is bounded at its 3′ terminus by the transcription initiation site and extends upstream (5′ direction) to include the minimum number of bases or elements necessary to initiate transcription at levels detectable above background. Within the promoter sequence will be found a transcription initiation site (conveniently defined by mapping with nuclease S1), as well as protein binding domains (consensus sequences) responsible for the binding of RNA polymerase. Eukaryotic promoters will often, but not always, contain “TATA” boxes and “CAT” boxes. Prokaryotic promoters contain Shine-Dalgarno sequences in addition to the -10 and -35 consensus sequences.
An “expression control sequence” is a DNA sequence that controls and regulates the transcription and translation of another DNA sequence. A coding sequence is “under the control” of transcriptional and translational control sequences in a cell when RNA polymerase transcribes the coding sequence into mRNA, which is then translated into the protein encoded by the coding sequence.
A “signal sequence” can be included before the coding sequence. This sequence encodes a signal peptide, N-terminal to the polypeptide, that communicates to the host cell to direct the polypeptide to the cell surface or to secrete the polypeptide into the media, and this signal peptide is clipped off by the host cell before the protein leaves the cell. Signal sequences can be found associated with a variety of proteins native to prokaryotes and eukaryotes.
The term “oligonucleotide,” as used herein in referring to the probe of the present invention, is defined as a molecule comprised of two or more ribonucleotides, preferably more than three. Its exact size will depend upon many factors which, in turn, depend upon the ultimate function and use of the oligonucleotide.
The term “primer” as used herein refers to an oligonucleotide, whether occurring naturally as in a purified restriction digest or produced synthetically, which is capable of acting as a point of initiation of synthesis when placed under conditions in which synthesis of a primer extension product, which is complementary to a nucleic acid strand, is induced, i.e., in the presence of nucleotides and an inducing agent such as a DNA polymerase and at a suitable temperature and pH. The primer may be either single-stranded or double-stranded and must be sufficiently long to prime the synthesis of the desired extension product in the presence of the inducing agent. The exact length of the primer will depend upon many factors, including temperature, source of primer and use of the method. For example, for diagnostic applications, depending on the complexity of the target sequence, the oligonucleotide primer typically contains 15-25 or more nucleotides, although it may contain fewer nucleotides.
The primers herein are selected to be “substantially” complementary to different strands of a particular target DNA sequence. This means that the primers must be sufficiently complementary to hybridize with their respective strands. Therefore, the primer sequence need not reflect the exact sequence of the template. For example, a non-complementary nucleotide fragment may be attached to the 5′ end of the primer, with the remainder of the primer sequence being complementary to the strand. Alternatively, non-complementary bases or longer sequences can be interspersed into the primer, provided that the primer sequence has sufficient complementarity with the sequence of the strand to hybridize therewith and thereby form the template for the synthesis of the extension product.
As used herein, the terms “restriction endonucleases” and “restriction enzymes” refer to bacterial enzymes, each of which cut double-stranded DNA at or near a specific nucleotide sequence.
A cell has been “transformed” by exogenous or heterologous DNA when such DNA has been introduced inside the cell. The transforming DNA may or may not be integrated (covalently linked) into chromosomal DNA making up the genome of the cell. In prokaryotes, yeast, and mammalian cells for example, the transforming DNA may be maintained on an episomal element such as a plasmid. With respect to eukaryotic cells, a stably transformed cell is one in which the transforming DNA has become integrated into a chromosome so that it is inherited by daughter cells through chromosome replication. This stability is demonstrated by the ability of the eukaryotic cell to establish cell lines or clones comprised of a population of daughter cells containing the transforming DNA. A “clone” is a population of cells derived from a single cell or common ancestor by mitosis. A “cell line” is a clone of a primary cell that is capable of stable growth in vitro for many generations.
Two DNA sequences are “substantially homologous” when at least about 75% (preferably at least about 80%, and most preferably at least about 90 or 95%) of the nucleotides match over the defined length of the DNA sequences. Sequences that are substantially homologous can be identified by comparing the sequences using standard software available in sequence data banks, or in a Southern hybridization experiment under, for example, stringent conditions as defined for that particular system. Defining appropriate hybridization conditions is within the skill of the art. See, e.g., Maniatis et al., supra; DNA Cloning, Vols. I & II, supra; Nucleic Acid Hybridization, supra.
It should be appreciated that also within the scope of the present invention are DNA sequences encoding specific binding members (antibodies) of the invention which code for e.g. an antibody having the same amino acid sequence as provided in
It should be understood that the codons specified above are for RNA sequences. The corresponding codons for DNA have a T substituted for U.
Mutations can be made in the sequences encoding the amino acids, antibody fragments, CDR region sequences set out in
The following is one example of various groupings of amino acids:
Amino Acids with Nonpolar R Groups
Amino Acids with Uncharged Polar R Groups
Amino Acids with Charged Polar R Groups (Negatively Charged at pH 6.0)
Aspartic acid, Glutamic acid
Another grouping may be those amino acids with phenyl groups:
Another grouping may be according to molecular weight (i.e., size of R groups):
Particularly preferred substitutions are:
Lys for Arg and vice versa such that a positive charge may be maintained;
Glu for Asp and vice versa such that a negative charge may be maintained;
Ser for Thr such that a free —OH can be maintained; and
Gln for Asn such that a free NH2 can be maintained.
Exemplary and preferred conservative amino acid substitutions include any of: glutamine (Q) for glutamic acid (E) and vice versa; leucine (L) for valine (V) and vice versa; serine (S) for threonine (T) and vice versa; isoleucine (I) for valine (V) and vice versa; lysine (K) for glutamine (Q) and vice versa; isoleucine (I) for methionine (M) and vice versa; serine (S) for asparagine (N) and vice versa; leucine (L) for methionine (M) and vice versa; lysine (L) for glutamic acid (E) and vice versa; alanine (A) for serine (S) and vice versa; tyrosine (Y) for phenylalanine (F) and vice versa; glutamic acid (E) for aspartic acid (D) and vice versa; leucine (L) for isoleucine (I) and vice versa; lysine (K) for arginine (R) and vice versa.
Amino acid substitutions may also be introduced to substitute an amino acid with a particularly preferable property. For example, a Cys may be introduced a potential site for disulfide bridges with another Cys. A His may be introduced as a particularly “catalytic” site (i.e., His can act as an acid or base and is the most common amino acid in biochemical catalysis). Pro may be introduced because of its particularly planar structure, which induces β-turns in the protein's structure.
Two amino acid sequences are “substantially homologous” when at least about 70% of the amino acid residues (preferably at least about 80%, and most preferably at least about 90 or 95%) are identical, or represent conservative substitutions. The CDR regions of two antibodies are substantially homologous when one or more amino acids are substituted with a similar or conservative amino acid substitution, and wherein the antibody/antibodies have the profile of binding and activities of one or more of IgM12 or IgM42 disclosed herein.
A “heterologous” region of the DNA construct is an identifiable segment of DNA within a larger DNA molecule that is not found in association with the larger molecule in nature. Thus, when the heterologous region encodes a mammalian gene, the gene will usually be flanked by DNA that does not flank the mammalian genomic DNA in the genome of the source organism. Another example of a heterologous coding sequence is a construct where the coding sequence itself is not found in nature (e.g., a cDNA where the genomic coding sequence contains introns, or synthetic sequences having codons different than the native gene). Allelic variations or naturally-occurring mutational events do not give rise to a heterologous region of DNA as defined herein.
A DNA sequence is “operatively linked” to an expression control sequence when the expression control sequence controls and regulates the transcription and translation of that DNA sequence. The term “operatively linked” includes having an appropriate start signal (e.g., ATG) in front of the DNA sequence to be expressed and maintaining the correct reading frame to permit expression of the DNA sequence under the control of the expression control sequence and production of the desired product encoded by the DNA sequence. If a gene that one desires to insert into a recombinant DNA molecule does not contain an appropriate start signal, such a start signal can be inserted in front of the gene.
The term “standard hybridization conditions” refers to salt and temperature conditions substantially equivalent to 5×SSC and 65° C. for both hybridization and wash. However, one skilled in the art will appreciate that such “standard hybridization conditions” are dependent on particular conditions including the concentration of sodium and magnesium in the buffer, nucleotide sequence length and concentration, percent mismatch, percent formamide, and the like. Also important in the determination of “standard hybridization conditions” is whether the two sequences hybridizing are RNA-RNA, DNA-DNA or RNA-DNA. Such standard hybridization conditions are easily determined by one skilled in the art according to well known formulae, wherein hybridization is typically 10-20° C. below the predicted or determined Tm with washes of higher stringency, if desired.
The term ‘agent’ means any molecule, including polypeptides, antibodies, polynucleotides, chemical compounds and small molecules. In particular the term agent includes compounds such as test compounds or drug candidate compounds.
The term ‘agonist’ refers to a ligand that stimulates the receptor the ligand binds to in the broadest sense.
The term ‘assay’ means any process used to measure a specific property of a compound. A ‘screening assay’ means a process used to characterize or select compounds based upon their activity from a collection of compounds.
The term ‘preventing’ or ‘prevention’ refers to a reduction in risk of acquiring or developing a disease or disorder (i.e., causing at least one of the clinical symptoms of the disease not to develop) in a subject that may be exposed to a disease-causing agent, or predisposed to the disease in advance of disease onset.
The term ‘prophylaxis’ is related to and encompassed in the term ‘prevention’, and refers to a measure or procedure the purpose of which is to prevent, rather than to treat or cure a disease. Non-limiting examples of prophylactic measures may include the administration of vaccines; the administration of low molecular weight heparin to hospital patients at risk for thrombosis due, for example, to immobilization; and the administration of an anti-malarial agent such as chloroquine, in advance of a visit to a geographical region where malaria is endemic or the risk of contracting malaria is high.
‘Therapeutically effective amount’ means that amount of a drug, compound, agent, antibody, or pharmaceutical agent that will elicit the biological or medical response of a subject that is being sought by a medical doctor or other clinician. In particular, with regard to neurological diseases or conditions, the term “effective amount” is intended to include an effective amount of a compound or agent, such as an antibody or fragment thereof, that will bring about a biologically meaningful change in a clinically relevant parameter of the disease. This may include a change in the amount of neurological injury or death observable or assessable upon imaging, a change in a functional parameter such as movement, speech or cognition, or the absence or reduction of such a change under conditions of risk or susceptibility. The phrase “therapeutically effective amount” is used herein to mean an amount sufficient to ameliorate or prevent, and preferably reduce by at least about 20 percent, at least about 30 percent, more preferably by at least 50 percent, more preferably by at least 70 percent, more preferably by at least 80 percent, most preferably by at least 90 percent, a clinically significant change in a measurable or assessable phenomenon, or feature of pathology, or assessment of function.
The term ‘treating’ or ‘treatment’ of any disease, condition, injury or infection refers, in one embodiment, to ameliorating the disease, condition, injury or infection (i.e., arresting the death of or injury to a cell or tissue, or reducing the manifestation, extent or severity of at least one of the clinical symptoms thereof). In another embodiment ‘treating’ or ‘treatment’ refers to ameliorating at least one physical parameter, which may not be discernible by the subject. In yet another embodiment, ‘treating’ or ‘treatment’ refers to modulating the disease, condition, injury or infection, either physically, (e.g., stabilization of a discernible symptom), physiologically, (e.g., stabilization of a physical parameter), or both. In a further embodiment, ‘treating’ or ‘treatment’ relates to slowing the progression of a disease or reducing the amount of injury, damage, death to cells or tissues.
The phrase “pharmaceutically acceptable” refers to molecular entities and compositions that are physiologically tolerable and do not typically produce an allergic or similar untoward reaction, such as gastric upset, dizziness and the like, when administered to a human.
As used herein, “pg” means picogram, “ng” means nanogram, “ug” or “μg” mean microgram, “mg” means milligram, “ul” or “μl” mean microliter, “ml” means milliliter, “I” means liter.
Neuroprotective agents are aimed at preventing and treating complications that result in CNS damage. Compounds or agents with capacity for neuroprotection have application in acute disorders such as stroke and injuries of the nervous system as well as in chronic diseases such as neurodegenerative disorders. Many of the underlying mechanisms of damage to neural tissues are similar in these conditions and a neuroprotective compound or agent could be used in more than one disorder. Diseases include cerebrovascular disorders, traumatic brain injury, spinal cord injury, Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis (ALS), multiple sclerosis, epilepsy, motor neuron disease(s) and ischemic neuropathy. Other applications include neuroprotection during anesthesia and surgery. Numerous products have been investigated for neuroprotective effects including those from the categories of free radical scavengers, anti-excitotoxic agents, apoptosis (programmed cell death) inhibitors, anti-inflammatory agents, neurotrophic factors, metal ion chelators, ion channel modulators and gene therapy. Several neuroprotective candidate products have reached clinical trials and failed to show significance, including NMDA antagonists and agents for reducing neurotransmitter release Clark W M et al (2000) Stroke 31(6):1234-9; Sarco R I et al (2001) JAMA 285 (13):1719-28; Albers, G W et al (2001) JAMA 286(21):2673-82). One challenge for neuroprotective agents is specificity and targeting so that an agent's effects are directed against injury or damaged/compromised neurons without significant activity against normal cells and thereby untoward, even potentially harmful side effects. The present invention now provides specific and tolerable agent(s) capable of crossing the blood brain barrier and targeting areas of injury, compromise or damage to effect protection, with minimal untoward effects on normal neurons.
The invention generally provides specific binding members, particularly antibodies which demonstrate neuron binding, with application as neuroprotective agents for use in diagnosis, monitoring, amelioration and treatment of diseases and conditions where neurons or nerve cells are compromised, including neurodegenerative conditions, nerve cell death and injury. The antibodies of the present invention have certain unique and remarkable qualities which make them particularly useful and applicable in neuroprotection and/or neuroregeneration and in diagnostics and therapeutics for neurological disease and conditions. The novel antibodies of the invention, particularly recombinant antibodies, are demonstrated herein to cross the blood brain barrier effectively and without any modification, to protect neurons from cell death, and to target neural lesions and sites of injury in the CNS. The antibodies improve nerve function and maintain axons in animal models of chronic axonal injury and demyelination. The antibodies have minimal toxicity in animals and do not exacerbate autoimmune conditions, as assessed in animal models.
The invention generally provides specific binding members, particularly antibodies which demonstrate neuron binding, with application as therapeutic agents, alone or in combination with other or alternative neuroactive agents, for the amelioration and treatment of diseases and conditions where neurons or nerve cells are compromised, including neurodegenerative conditions, nerve cell death and injury. The application provides evidence of the capability and therapeutically relevant activity of antibodies of the present invention, including IgM12, in animal models of neurological diseases or deficits. In particular, studies provided herein demonstrate capability and activity in a TMEV model, in a recognized animal model of motor neuron disease particularly ALS, and provides studies in spinal cord injury models. In particular, the present application provides evidence of the capability and therapeutically relevant activity of antibodies of the present invention, including IgM12, in animal models of stroke and cerebral thrombosis or cerebral ischemia. The studies provided herein demonstrate capability and activity in a in a recognized animal model of stroke and cerebral ischemia. Compositions for use in the amelioration or treatment of any of such diseases or in the prevention of nerve injury or protection of nerves in instances of compromise or risk of compromise are provided.
Prior studies with IgM12 and IgM42 have shown that the serum-derived antibody binds to CNS neurons, supports neurite extension on antibody-coated substrate, and override the neurite extension inhibition of CNS myelin in in vitro studies (Warrington A et al (2004) J Neuropath Exp Neurol 63(5):461-473). Studies of sHIgM12 injected in TMEV animals showed increased spontaneous nocturnal activity, however, virus titers were not assessed in the animals and possible anti-viral effects could not be determined (Rodrigues M et al (2009) Neurology 72:1269-1276). The studies described herein provide fully human recombinant 12 and the sequence of the antibody 42 as well as recombinant rHIgM42. Studies demonstrating remarkable neuroprotective and therapeutically-relevant effects of these serum-derived and recombinant antibodies in animals and animal models of disease as well as their specific binding/targeting to sites of neural injury are now provided. In particular studies using animal models of cerebral ischemia and stroke provide demonstration of therapeutically-relevant effects of these serum-derived and recombinant antibodies, particularly recombinant IgM12, rHIgM12, in stroke, cerebral ischemia, and conditions of or resulting from loss of blood flow in or to the brain or cells in the CNS.
Auto reactive human mAbs fall under the classification of human natural autoantibodies (NatAbs) (Cohen I. R. (2007) J Autoimmun 29:246-249). NatAbs are part of our human immunoglobulin repertoire (Cohen, I. R., and M. Schwartz (1999) Journal of neuroimmunology 100:111-114), naturally made from our own genes, usually without somatic mutations and may function to stimulate cell processes or remove cell debris (Lutz, H U (2007) J Autoimmun 29:287-294). NatAbs react to self antigens, whereas conventional Abs react to exogenous antigens. NatAbs are of relatively low affinity, usually poly reactive, and are frequently IgMs. The mechanism of the action of these human IgMs appears to be similar, acting through membrane micro domains. NatAbs are by definition polyreactive, therefore identifying the relevant antigen for a specific in vivo function can be a challenge. Without being bound by theory, it is presently understood that these IgMs bind to membrane microdomains cross-linking molecules on the cell surface. Molecules not normally in context are brought together assembling a signaling complex (Rodriguez, M., A. E. Warrington, and L. R. Pease (2009) Neurology 72:1269-1276).
Accordingly, therapeutic molecules were identified by screening for auto reactive human monoclonal antibodies (mAbs) from the sera of individuals that carry the mAbs in high concentration without Ab-mediated disease. Such mAbs are tested for binding to the surface of nervous system cells without regard for antigen. The mAbs are then tested for the ability to modulate a disease model. This method of identifying mAbs with biologic efficacy is different than the methodology commonly used by the pharmaceutical industry (Rodriguez, M., A. E. Warrington, and L. R. Pease (2009) Neurology 72:1269-1276). It has been demonstrated that certain human IgMs can promote remyelination (Warrington A E et al (2000) Proc Natl Acad Sci USA 97:6820-6825). For example, one such IgM is recombinant human monoclonal rHIgM22 that promotes remyelination (Mitsunaga Y B et al (2002) Faseb J 16:1325-1327). Antibody rHIgM22 binds to oligodendrocytes and myelin and promotes CNS remyelination in virus and toxin induced models of MS (Warrington A E et al (2000) Proc Natl Acad Sci USA 97:6820-6825; Bieber A J et al (2002) Glia 37:241-249). Spinal cord remyelination is induced after a single low dose of rHIgM22 (Warrington A E et al (2007) J Neurosci Res 85:967-976).
It is remarkable that one intraperitoneal (i.p.) treatment with a short lived molecule (15 hr half life estimated in mice) promotes maximal tissue repair within 5 weeks in a model of MS with little inherent spontaneous repair. After peripheral injection, rHIgM22 crosses the blood brain barrier (BBB) and accumulates within brain and spinal cord lesions of mice with demyelination. Ferritin bead labeled rHIgM22 has been detected in lesions in vivo by MRI (Pirko I et al (2004) Faseb J 18:1577-1579). An additional serum human IgM antibody with remyelinating capability, sHIgM46, and its recombinant counterpart rHIgM46, has been also been described. The serum-derived antibodies sHIgM22 and sHIgM46, and recombinant versions thereof, and methods for remyelination are described, e.g., in WO 0185797. The rHIgM22 antibody and methods thereof is covered, e.g., by U.S. Pat. Nos. 7,473,423 and 7,807,166.
The invention provides human antibodies, including monoclonal antibodies and particularly recombinant antibodies, which demonstrate activity in the promotion, stimulation, protection and/or regeneration of neurons in the central nervous system. The present antibodies, including fragments thereof, demonstrate activity in neuroprotection, neuronal and axon preservation and regeneration in the prevention or reduction of injury-mediated nerve cell death in the central nervous system. The antibodies are applicable in the treatment or amelioration of diseases or conditions, or in the prevention or reduction of nerve cell deficits and nerve cell death or apoptosis associated with diseases or conditions, particularly where nerves are damaged, injured or otherwise compromised. Conditions or diseases for use or application of the antibodies of the invention include scenarios where loss of structure, function or survival of neurons is involved or associated including brain injury or trauma, spinal cord injury (SCI), nerve injury, head injury, conditions where blood supply to the brain is reduced or compromised, infectious diseases of the brain, neurodegenerative diseases. Exemplary such diseases or conditions include spinal cord injury (SCI), Amyolotropic Lateral Sclerosis (ALS), multiple sclerosis (MS), Alzheimer's disease, stroke, Parkinson's disease, Huntington's disease, prenatal anoxia/perinatal ischemia and/or Cerebral Palsy, encephalopathy, myelopathy, and motor neuron diseases.
The neuromodulatory agents or antibodies of the invention have one or more of the following characteristics: they protect and/or stabilize neurons; they target sites in the CNS or nerve cell damage, compromise or injury; and/or block cell death, e.g. hydrogen-peroxide induced cell death. The invention provides neuron-binding monoclonal antibodies of the invention are capable of promoting neurite extension and protecting neurons from damage for diagnostic and therapeutic purposes in the central nervous system. In particular, recombinant antibodies are provided, wherein said antibodies recognize and are capable of binding neurons, including cortical neurons, hippocampal neurons, cerebellar granule cells and retinal ganglion cells.
The present invention provides exemplary antibody(ies) or fragment(s) thereof, antibody 12 and antibody 42, particularly serum derived or recombinant IgM12 or IgM42. In a further particular aspect, the antibody of the invention comprises the amino acid sequence of antibody 12 or 42 including as set out in
Panels of recombinant antibodies or fragments thereof, including Fab fragments or phage display libraries, which are capable of recognizing neurons, particularly human neurons, can be screened for various properties; i.e., affinity, isotype, epitope, stability, etc. Of particular interest are antibodies that mimic the activity of exemplary antibodies IgM12 and IgM42, and have the ability to bind neurons and to protect neurons from cell death or injury, such as for example peroxide mediated cell death. Such antibodies can be readily identified and/or screened in specific binding and activity assays. Recombinant antibodies comprising the antigen binding region or the heavy and/or light chain CDR regions of the present antibodies IgM12 and/or IgM42, may be generated and screened for activity.
In general, the CDR regions, comprising amino acid sequences substantially as set out as the CDR regions of
Substitutions may be made in the variable region sequence outside of the CDRs so as to retain the CDR sequences. Thus, changes in the variable region sequence or alternative non-homologous or veneered variable region sequences may be introduced or utilized, such that the CDR sequences are maintained and the remainder of the variable region sequence may be substituted. Alternatively, substitutions may be made particularly in the CDRs. CDR sequences for the antibodies of the present invention are set out and described herein including in
The structure for carrying the CDRs of the invention will generally be of an antibody heavy or light chain sequence or substantial portion thereof in which the CDR regions are located at locations corresponding to the CDR region of naturally occurring VH and VL antibody variable domains encoded by rearranged immunoglobulin genes. The structures and locations of immunoglobulin variable domains may be determined by reference to Kabat, E. A. et al, Sequences of Proteins of Immunological Interest. 4th Edition. US Department of Health and Human Services. 1987, and updates thereof, now available on the Internet (immuno.bme.nwu.edu). The variable domains may be derived from any germline or rearranged human variable domain, or may be a synthetic variable domain based on consensus sequences of known human variable domains. The CDR-derived sequences of the invention, as defined in the preceding paragraph, may be introduced into a repertoire of variable domains lacking CDR regions, using recombinant DNA technology.
For example, Marks et al (Bio/Technology, 1992, 10:779-783) describe methods of producing repertoires of antibody variable domains in which consensus primers directed at or adjacent to the 5′ end of the variable domain area are used in conjunction with consensus primers to the third framework region of human VH genes to provide a repertoire of VH variable domains lacking a CDR/CDRs. Marks et al further describe how this repertoire may be combined with a CDR of a particular antibody. The repertoire may then be displayed in a suitable host system such as the phage display system of WO92/01047 so that suitable specific binding members may be selected. A repertoire may consist of from anything from 104 individual members upwards, for example from 106 to 108 or 1010 members. Analogous shuffling or combinatorial techniques are also disclosed by Stemmer (Nature, 1994, 370:389-391), who describes the technique in relation to a β-lactamase gene but observes that the approach may be used for the generation of antibodies.
A further alternative is to generate novel VH or VL regions carrying the CDR-derived sequences of the invention using random mutagenesis of, for example, the Ab VH or VL genes to generate mutations within the entire variable domain. Such a technique is described by Gram et al (1992, Proc. Natl. Acad. Sci., USA, 89:3576-3580), who used error-prone PCR. Another method which may be used is to direct mutagenesis to CDR regions of VH or VL genes. Such techniques are disclosed by Barbas et al, (1994, Proc. Natl. Acad. Sci., USA, 91:3809-3813) and Schier et al (1996, J. Mol. Biol. 263:551-567). All the above described techniques are known as such in the art. The skilled person will be able to use such techniques to provide specific binding members of the invention using routine methodology in the art.
A substantial portion of an immunoglobulin variable domain will comprise at least the three CDR regions, together with their intervening framework regions. Preferably, the portion will also include at least about 50% of either or both of the first and fourth framework regions, the 50% being the C-terminal 50% of the first framework region and the N-terminal 50% of the fourth framework region. Additional residues at the N-terminal or C-terminal end of the substantial part of the variable domain may be those not normally associated with naturally occurring variable domain regions. For example, construction of specific binding members of the present invention made by recombinant DNA techniques may result in the introduction of N- or C-terminal residues encoded by linkers introduced to facilitate cloning or other manipulation steps. Other manipulation steps include the introduction of linkers to join variable domains of the invention to further protein sequences including immunoglobulin heavy chains, other variable domains (for example in the production of diabodies) or protein labels as provided herein and/or known to those of skill in the art.
Although in a preferred aspect of the invention recombinant antibodies comprising a pair of binding domains based on sequences substantially set out in
Specific binding members of the present invention may further comprise antibody constant regions or parts thereof. For example, recombinant antibodies based on the VH and VL sequences of
The antibodies, or any fragments thereof, may be conjugated or recombinantly fused to any cellular toxin, bacterial or other, e.g. pseudomonas exotoxin, ricin, or diphtheria toxin. The part of the toxin used can be the whole toxin, or any particular domain of the toxin. Such antibody-toxin molecules have successfully been used for targeting and therapy of different kinds of cancers, see e.g. Pastan, Biochem Biophys Acta. 1997 Oct. 24; 1333(2):C1-6; Kreitman et al., N Engl J Med. 2001 Jul. 26; 345(4):241-7; Schnell et al., Leukemia. 2000 January; 14(1):129-35; Ghetie et al., Mol Biotechnol. 2001 July; 18(3):251-68. Bi- and tri-specific multimers can be formed by association of different scFv molecules and have been designed as cross-linking reagents for T-cell recruitment into tumors (immunotherapy), viral retargeting (gene therapy) and as red blood cell agglutination reagents (immunodiagnostics), see e.g. Todorovska et al., J Immunol Methods. 2001 Feb. 1; 248(1-2):47-66; Tomlinson et al., Methods Enzymol. 2000; 326:461-79; McCall et al., J Immunol. 2001 May 15; 166(10):6112-7.
Antibodies of the invention may be labeled with a detectable or functional label. Detectable labels include, but are not limited to, radiolabels such as the isotopes 3H, 14C, 32P, 35S, 36Cl, 51Cr, 57Co, 58Co, 59Fe, 90Y, 121I, 124I, 125I, 131I, 111In, 117Lu, 211At, 198Au, 67Cu, 225Ac, 213Bi, 99Tc and 186Re, which may be attached to antibodies of the invention using conventional chemistry known in the art of antibody imaging. Labels also include fluorescent labels (for example fluorescein, rhodamine, Texas Red) and labels used conventionally in the art for MRI-CT imaging. They also include enzyme labels such as horseradish peroxidase, β-glucoronidase, β-galactosidase, urease. Labels further include chemical moieties such as biotin which may be detected via binding to a specific cognate detectable moiety, e.g. labeled avidin. Functional labels include substances which are designed to be targeted to the site of compromise, damage or injury to provide protection of or cause destruction of neural tissue. Such functional labels include cytotoxic drugs such as 5-fluorouracil or ricin and enzymes such as bacterial carboxypeptidase or nitroreductase, which are capable of converting prodrugs into active drugs at the site. Immunoconjugates or antibody fusion proteins of the present invention are contemplated, wherein the antibodies and fragments thereof are conjugated or attached to other molecules or agents further include, but are not limited to binding members conjugated to a chemical ablation agent, toxin, immunomodulator, cytokine, cytotoxic agent, chemotherapeutic agent or drug. When radioactive labels are used, known currently available counting procedures may be utilized to identify and quantitate the specific binding members. In the instance where the label is an enzyme, detection may be accomplished by any of the presently utilized colorimetric, spectrophotometric, fluorospectrophotometric, amperometric or gasometric techniques known in the art.
In vivo animal models of complications that result in CNS damage, including nerve cell injury or damage or of neurodegenerative conditions may be utilized by the skilled artisan to further or additionally screen, assess, and/or verify the antibodies or fragments thereof of the present invention, variants thereof, or of combinations thereof, or of combinations with other CNS reactive antibodies. Such animal models include, but are not limited to models of conditions or diseases associated with nerve cell damage, compromise, alteration, death, injury or degeneration. Models include those of or mimicking aspects of stroke, brain injury, ischemia, MS, Alzheimer's disease, Huntington's disease, Parkinson's disease, dementia, encephalitis, meningitis, ALS or motor neuron disease. Stroke models utilizing middle cerebral artery occlusion in primates, such as baboons, monkeys or macaques are known in the art and may be suitable (Young A et al (1997) Stroke 28:1471-1476; delZoppo G J et al (1986) Stroke 17:1254-1265; Marshall and Ridley 91996) Neurodegeneration 5:275-286). MS models such as TMEV are known and described and utilized herein. SOD mouse models for ALS and motor neuron disease are known and described and utilized herein (Gurney M E et al (1994) Science 264:1772-1775).
The Examples and studies provided herein demonstrate efficacy and application of the antibodies provided, described and contemplated herein in models of stroke, ischemia and instances of hypoxia to the brain or neuronal cells. Thus, in a particular aspect, the present invention relates to use of the antibodies in intervention relating to stroke, cerebral ischemia, suspected or presumed stroke, transient ischemic attacks (TIAs) or minor strokes, or in individuals at high risk of stroke or a cerebral ischemic event or brain hypoxic event.
In the event of a stroke, or suspected stroke, fast treatment is important as the worst damage from a stroke usually occurs within the first few hours. Faster treatment results in less initial and permanent or long-term damage. Treatment depends on the nature or cause of stroke, whether restoring blood flow in ischemic stroke due to a blood clot (ischemic) or by controlling bleeding for a hemorrhagic stroke. CT scans and MRIs are utilized to assess or diagnose the type or extent of stroke. Current treatments for acute ischemic stroke include IV thrombolytic therapy, particularly with tissue-type plasminogen activator (tPA), and endovascular therapies, including intra-arterial thrombolytic therapy and the use of clot retrieval devices. However, tPA has a limited therapeutic window and is typically administered within 3 hr of stroke onset. Protecting damaged neurons following cerebral ischemia is a promising strategy to limit permanent disability. While therapies that modulate the inflammatory response can have neuro-protective properties, there are currently very few drugs that act directly on neurons to protect them.
A number of medications that can help prevent stroke in high-risk patients, particularly those who have had previous transient ischemic attacks (TIAs) or minor strokes, are available. These drugs fall into two main categories—anticoagulants and antiplatelet agents. Examples of anticoagulants include heparin, Coumadin, warfarin, ximelagatran and Exanta. These drugs work by thinning the blood to help prevent clotting, including in instances of deep vein thromboses and pulmonary emboli, and are very effective in helping to prevent stroke in patients with atrial fibrillation. Antiplatelet agents include aspirin, Persantine, dipyridamole, Plavix and clopidogrel. These agents prevent or reduce platelet aggregation and thereby reduce clots or clot formation and can reduce the risk of stroke in patients who have had TIAs or prior ischemic strokes. Despite the availability of thrombolytic therapy, stroke remains the third leading cause of death in the United States and the most common cause of adult disability. Scientists and physicians continue to seek ways to achieve better functional recovery in stroke patients. Neuroprotective agents have generated intense interest and have the potential to make the brain less susceptible to the damaging effects of stroke.
In assessing and evaluating the extent and effects of a stroke, clinicians and medical personnel review and consider various aspects of the patient's capabilities and functions. In addition to imaging techniques to identify and localize the area of a stroke or clot and ischemia, patients are evaluated using stroke assessment scales and functional assessment scales. Numerous scales are accepted or utilized and will be recognized and known to clinicians and those of skill in the art. Functional assessment scales include for example the Berg Balance Scale, Lawton Instrumental Activities of Daily Living (IADL) Scale, Rankin or modified Rankin Scale, and NIH Stroke Scale (NIHHS). These scales assess and determine several or a number of various parameters, including upper and lower extremity motor function, limb ataxia, sensory function, language, articulation, attention, gaze and visual function, arm, hand and leg power and movement. Patients can be evaluated on one or more scale just after the stroke or ischemic event, following the event, before and after treatment, for evaluation of possible or candidate treatments of agents, for comparison of treatments or agents and over time, including days, weeks, months, years.
The antibodies, fragments thereof and recombinant antibodies comprising the variable region sequences according to the invention may be used in methods of treatment, prevention or diagnosis of the human or animal body, such as a method of neuroprotection in a mammal, particularly in instances of established, suspected or possible stroke or cerebral ischemia, which comprises administering to said mammal an effective amount of the antibodies, fragments thereof and recombinant antibodies of the invention. Recombinant antibodies or fragments thereof comprising the CDR domain region sequences according to the invention may be used in such methods. The agents of the invention, particularly recombinant antibodies or fragments thereof may be used in instances of established, suspected or possible stroke or cerebral ischemia, including as neuroprotective agents in methods for prevention, treatment or amelioration of nerve injury, damage or compromise and complications that can, may or do result in CNS damage. The methods of the invention are applicable where loss of structure, function or survival of neurons is involved or associated including brain injury or trauma, spinal cord injury (SCI), nerve injury, head injury, conditions where blood supply or oxygen to the brain is reduced or compromised. Exemplary such diseases or conditions for treatment, prevention or amelioration in accordance with the methods of the invention include stroke, TIAs, cerebral ischemia, prenatal anoxia/perinatal ischemia and/or Cerebral Palsy.
The agents of the invention, particularly recombinant antibodies or fragments thereof may be used as agents in methods for prevention, treatment or amelioration of stroke or cerebral ischemia. The present invention provides methods of treating or ameliorating stroke or cerebral ischemia comprising administering an antibody of the present invention, particularly recombinant antibody, particularly antibody IgM12 or recombinant IgM12, including an antibody or fragment thereof comprising heavy chain CDR sequences CDR1 GGSVSLYY (SEQ ID NO:31), CDR2 GYIYSSGST (SEQ ID NO:32) and CDR3 ARSASIRGWFD (SEQ ID NO:33), and light chain CDR sequences CDR1 QSISSY (SEQ ID NO: 34), CDR2 AAS (SEQ ID NO:35) and CDR3 QQSYHTPW (SEQ ID NO:36), as set out in
The present invention provides methods of treating or ameliorating diseases or conditions in mammals where nerves are compromised, injured or damaged or scenarios where nerves or neurons are susceptible or at risk of compromise, injury or damage comprising administering a recombinant antibody or fully human antibody or fragment thereof selected from IgM12 and IgM42. Methods of the invention may comprise administration of more than one antibody or fragment, including combinations of antibody IgM12 and 42. In a further such method, one or more of antibody IgM12 and/or of antibody IgM42 may be combined with another CNS active antibody, particularly including one or more of antibodies rHIgM22 and/or rHIgM46. Combinations of antibodies may be administered collectively or in series, and at various times and various amounts or concentrations. Thus, antibody 12 and/or 42 may be administered in combination with antibody 22 and/or 46, by combined administration or in series, separated by a short length of time or longer length of time, including by hours, days or weeks. Antibody 12 and/or 42 may particularly be administered in combination with antibody 22 and/or 46 (sHIgM22, rHIgM22, sHIgM46 or rHIgM46), by combined administration or in series for the treatment of amelioration of a disease or condition involving neurodegeneration, and particularly including demyelination. In one such method antibody 12 and/or 42 is administered in combination with antibody 22 and/or 46, by combined administration or in series for the treatment of amelioration of a demyelinating disease or condition, particularly including multiple sclerosis (MS). The variable heavy and light chain sequences of antibody IgM22 are set out in SEQ ID NO: 43 and SEQ ID NO: 44 respectively. The variable heavy and light chain sequences of antibody IgM46 are set out in SEQ ID NO: 45 and SEQ ID NO: 46 respectively. One or more of antibody IgM12 and/or of antibody IgM42 may be combined with one or more remyelinating antibody comprising (a) heavy chain variable region CDRs comprising CDR1 sequence SSGMH CDR2 sequence V(I)ISYDGSRKYYADSVKG and CDR3 sequence GVTGSPTLDY, and light chain variable region CDRs comprising CDR1 sequence SGSSSNIGNNFVS CDR2 sequence DITKRPS and CDR3 sequence G(E)TWDSSLSAV V; or (b) heavy chain variable region CDRs comprising CDR1 sequence SGFTFSSYW CDR2 sequence IKKDGSEK and CDR3 sequence ARPNCGGDCYLPWYFD, and light chain variable region CDRs comprising CDR1 sequence QSVLYSSNNKNY CDR2 sequence YWAS and CDR3 sequence QQYYNTPQA.
Methods of the invention may include administration of the antibodies of the invention alone or in combination with, in series with, or subsequent to administration of stroke or ischemic agents including one or more of thrombolytic agents, anti-platelet agents, blood pressure modulators, anti-hypertensives, anti-inflammatories, agents that alter excitatory amino acids or their receptors, intracellular calcium modulators, channel modulators free-radical scavengers. In a particular aspect, the antibodies or active fragments thereof, particularly antibody IgM12 and/or IgM42, are administered with thrombolytic agents and/or anti-platelet agents. In an aspect, the antibodies may be administered with or after a thrombolytic agent, such as TPA.
Administered with may include at about the same time, shortly after, minutes after, up to an hour after, hours after, a day after. Administration of the antibody(ies), either alone particularly as antibodies IgM12 or IgM42, or in combination, or with other agents, may be within or after the 3 hour, 4 hour, 5 hour, 6 hour, up to 9 hour therapeutic window for TPA or thrombolytic agent administration following a documented or suspected stroke or cerebral ischemic event. Antibody(ies) may be administered in a single dose or multiple dose. By way of example and not limitation, antibody(ies) may be administered within 3 hours, after 3 hours, up to 4 hours, up to 5 hours, up to 6 hours, up to 8 hours, up to 12 hours, up to 24 hours, up to a day, up to 2 days, up to 3 days, up to several days, up to a week, or longer following a documented or suspected stroke or cerebral ischemic event. Antibody(ies) may, by way of example and not limitation, be initially administered within 3-6 hours following a documented or suspected stroke or cerebral ischemic event, followed by one or more additional administration of antibody(ies) up to one day, 2 days, 3 days, 4 days, 5 days, 6 days, a week, more than a week, 2 weeks, more than 2 weeks, or later following the initial or any subsequent administration. Dosing may be modulated based on the response or function of the patient. For example, the patient may be evaluated, for example using a stroke scale such as NIHSS before or after, before and after, or following initial administration of antibody, and antibody administration may be modified or continued or altered based on such a scale or other neurological or motor evaluation of the patient. In a particular aspect of the invention and the method, the antibody(ies) are effective in improving stroke scale measures or other neurological or functional scales, particularly when compared to no antibody administration, administration of TPA or other agent alone, or versus an alternative agent, including an alternative antibody or neuroprotective agent.
Thus, as demonstrated herein in animal models of stroke, animals administered the antibody(ies) of the invention demonstrate improved functional activity. The antibody(ies) of the present invention are effective in improving locomotor activity, including improvement in horizontal motor function, by administration thereof after a stroke or cerebral ischemia. Following ischemic injury or stroke, the disability associated with clinical deficits is primarily due to dysfunction of neurons. The lack of functional recovery is in part attributed to the restriction of regeneration and neuroplasticity (Walmsley, A. R., and Mir, A. K. (2007) Current Pharmaceutical Design 13:2470-2484). Stroke may result in a altered motor function such as an inability to move one or more limbs on one side of the body, cognitive effects such as an inability to understand or formulate speech, or other deficits including visual effects such as an inability to see one side of the visual field. In an aspect of the invention and its methods, the antibody(ies) of the invention are effective to prevent or reverse stroke-related neurologic deficits. Thus, the antibody(ies) of the invention can ameliorate one or more neurological symptom or deficit in instances of stroke or cerebral ischemia. The antibody(ies) of the invention are effective in mitigating the neurological effects or damage, particularly in the CNS, in the event or instance of a stroke. The antibody(ies) are of use in methods of reducing neurological damage or neuronal cell death, and effective to preserve or protect neurons in the event of a stroke or cerebral ischemia.
In an aspect of the invention, the antibodies, fragments thereof and recombinant antibodies comprising the variable region sequences according to the invention, may be utilized in methods or administered in compositions for improvement or stabilization of neurological function or of motor function in instances, particularly during, following, or upon a stroke or cerebral ischemic event, wherein nerves are compromised, injured or damaged or scenarios where nerves or neurons are susceptible or at risk of compromise, injury or damage. In a particular aspect, the antibodies or fragments thereof are utilized or administered in early or initial stages of a disease, trauma, or condition, such as a stroke or suspected stroke, or repeated over the course or duration of a disease, trauma, or condition, such as repeated following a stroke, so as to facilitate or maintain the improvement or stabilization of neurological function or motor function, including or selected from movement, such as walking, or cognitive function, such as recall or recognition.
Antibodies of the present invention may be administered to a patient in need of treatment via any suitable route, including by injection intraperitoneally, into the bloodstream or CSF, or directly into the site of injury or compromise. A particular advantage of the exemplary antibodies of the present invention is that they cross the BBB and can therefore target the CNS even on i.p. administration. The precise dose will depend upon a number of factors, including whether the antibody is for diagnosis or for treatment, the size or extent and location of the injury, the precise nature of the antibody (whether whole antibody, fragment, diabody, etc), and the nature of any detectable or functional label attached to the antibody. Where a radionuclide is used for therapy, a suitable maximum single dose may be about 45 mCi/m2, to a maximum of about 250 mCi/m2. Preferable dosage is in the range of 15 to 40 mCi, with a further preferred dosage range of 20 to 30 mCi, or 10 to 30 mCi. Such therapy may require bone marrow or stem cell replacement. Clinically-approved naked antibodies are generally administered in mg quantities, with adult doses of 20 to 2000 mg protein per dose, 20 to 1500 mg protein per dose, or 20 to 1000 mg protein per dose, or 20 to 500 mg protein per dose, or 20 to 100 mg protein per dose. Clinically-approved injectable monoclonal antibodies are administered in mg amounts, 3-5 mg/kg, 5-10 mg/kg per dose, 300-400 mg/dose, 300-500 mg/dose (Newsome B W and Ernstoff M S (2008) Br J Clin Pharmacol 66(1):6-19; herceptin.net, tysabri.net, avastin.net, remicade.com). It is notable that the remyelinating antibody IgM22 has been shown to be effective in comparatively significantly lower doses, in the μg range, and is capable of crossing the BBB to be active in the CNS with even a single dose of antibody (WO 2004/110355; Warrington A E et al (2007) J Neurosci Res 85(5):967-976). Recombinant IgM12 antibody is shown herein to have therapeutically relevant activity in animal models upon a single i.p. dose in the μg range. Thus dosing of the antibodies of the present invention, in either single dose, or multiple and/or periodic doses, in the range of μgs per dose or μg/kg doses, or in low mg per dose (100 μg-1 mg, less than 1 mg, 1 mg-5 mg, 1 mg-10 mg, 5 mg-15 mg, 10 mg-20 mg per dose), may be applicable and effective. A dose for a single treatment of an adult patient, may be proportionally adjusted for children and infants, and also adjusted for other antibody formats, in proportion for example to molecular weight. Treatments may be repeated at daily, twice-weekly, weekly or monthly intervals, at the discretion of the physician. One advantage of the exemplary antibodies is that they cross the BBB and target sites of damage or injury, thus facilitating the use of lower and potentially fewer doses to achieve suitable effects.
Antibodies or fragments of the present invention will usually be administered in the form of a pharmaceutical composition, which may comprise at least one component in addition to the antibody(ies) or fragments of the invention. Thus pharmaceutical compositions according to the present invention, and for use in accordance with the present invention, may comprise, in addition to active ingredient, a pharmaceutically acceptable excipient, carrier, buffer, stabilizer or other materials well known to those skilled in the art. Such materials should be non-toxic and should not interfere with the efficacy of the active ingredient. The precise nature of the carrier or other material will depend on the route of administration, which may be oral, or by injection, e.g. intravenous, or by deposition at a tumor site.
Pharmaceutical compositions for oral administration may be in tablet, capsule, powder or liquid form. A tablet may comprise a solid carrier such as gelatin or an adjuvant. Liquid pharmaceutical compositions generally comprise a liquid carrier such as water, petroleum, animal or vegetable oils, mineral oil or synthetic oil. Physiological saline solution, dextrose or other saccharide solution or glycols such as ethylene glycol, propylene glycol or polyethylene glycol may be included. For intravenous, injection, or injection at the site of affliction, the active ingredient may be in the form of a parenterally acceptable aqueous solution which is pyrogen-free and has suitable pH, isotonicity and stability. Those of relevant skill in the art are well able to prepare suitable solutions using, for example, isotonic vehicles such as Sodium Chloride Injection, Ringer's Injection, Lactated Ringer's Injection. Preservatives, stabilizers, buffers, antioxidants and/or other additives may be included, as required.
A composition may be administered alone or in combination with other treatments, therapeutics or agents, either simultaneously or sequentially dependent upon the condition to be treated. Compositions comprising combinations of one or more recombinant antibody or fragment thereof as described herein are contemplated. In addition, the present invention contemplates and includes compositions comprising the antibody or fragment thereof, herein described and other agents or therapeutics such as neuroactive agents or therapeutics, anti-inflammatory agents, neurotransmitter release modulating agents, neuroreceptor ligands or agonists or antagonists, calcium channel agents, immune modulators, or other CNS reactive antibodies. Compositions comprising combinations of one or more recombinant antibody or fragment thereof as described herein are contemplated. Other treatments or therapeutics may include the administration of suitable doses of pain relief drugs such as non-steroidal anti-inflammatory drugs (e.g. aspirin, paracetamol, ibuprofen or ketoprofen) or opiates such as morphine, or anti-emetics. In addition, the composition may be administered with immune modulators, such as interleukins, tumor necrosis factor (TNF) or other growth factors, colony stimulating factors, cytokines or hormones such as dexamethasone which stimulate the immune response and reduction or elimination of cancer cells or tumors. The composition may also be administered with, or may include combinations along with other CNS reactive antibodies, particularly including remyelinating antibodies, including rHIgM22 and/or rHIgM46.
The present invention further contemplates therapeutic compositions useful in practicing the therapeutic methods of this invention. A subject therapeutic composition includes, in admixture, a pharmaceutically acceptable excipient (carrier) and one or more of an antibody, polypeptide analog thereof or fragment thereof, as described herein as an active ingredient. In a preferred embodiment, the composition comprises an antigen capable of modulating the specific binding of the present binding member/antibody with a target cell. The preparation of therapeutic or pharmaceutical compositions which contain antibodies, polypeptides, or active fragments as active ingredients is well understood in the art. Typically, such compositions are prepared as injectables, either as liquid solutions or suspensions. However, solid forms suitable for solution in, or suspension in, liquid prior to injection can also be prepared. The preparation can also be emulsified. The active therapeutic ingredient is often mixed with excipients which are pharmaceutically acceptable and compatible with the active ingredient. Suitable excipients are, for example, water, saline, dextrose, glycerol, ethanol, or the like and combinations thereof. In addition, if desired, the composition can contain minor amounts of auxiliary substances such as wetting or emulsifying agents, pH buffering agents which enhance the effectiveness of the active ingredient. An antibody or active fragment can be formulated into the therapeutic composition as neutralized pharmaceutically acceptable salt forms. Pharmaceutically acceptable salts include the acid addition salts (formed with the free amino groups of the polypeptide or antibody molecule) and which are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids as acetic, oxalic, tartaric, mandelic, and the like. Salts formed from the free carboxyl groups can also be derived from inorganic bases such as, for example, sodium, potassium, ammonium, calcium, or ferric hydroxides, and such organic bases as isopropylamine, trimethylamine, 2-ethylamino ethanol, histidine, procaine, and the like.
The therapeutic antibody- or active fragment-containing compositions are conventionally administered intraperitoneally or intravenously, as by injection of a unit dose, for example. The term “unit dose” when used in reference to a therapeutic composition of the present invention refers to physically discrete units suitable as unitary dosage for humans, each unit containing a predetermined quantity of active material calculated to produce the desired therapeutic effect in association with the required diluent; i.e., carrier, or vehicle.
The compositions are administered in a manner compatible with the dosage formulation, and in a therapeutically effective amount. The quantity to be administered depends on the subject to be treated, capacity of the subject's system to utilize the active ingredient, and degree of neuron binding capacity desired or extent of neural injury. Precise amounts of active ingredient required to be administered depend on the judgment of the practitioner and are peculiar to each individual. Suitable regimes for initial administration and follow on administration are also variable, and may include an initial administration followed by repeated doses at one or more hour, day, week or month intervals by a subsequent injection or other administration. Alternatively, continuous infusion or administration sufficient to maintain appropriate and sufficient concentrations in the blood, CNS or at the site of desired therapy are contemplated.
The timing of administration may vary and may be determined by the skilled artisan or medical practitioner, based on the teaching of the specification, the clinical parameters of the patient or subject, the status or severity of the condition or disease, or the degree or nature of neural injury, involvement or compromise. Thus, improvement in neural function or enhanced protection of neurons, e.g. from death or compromise, may be enhanced by administration early in the onset or clinical demonstration of a disease, so as to minimize the extent of neurological damage or compromise. In an aspect, timing of administration is coordinated with neurological function assessments, status determination and/or other clinical evaluations so as to minimize or alleviate progression of disease of neurological impairment or damage.
The present invention also relates to a variety of diagnostic applications, including methods for detecting or determining nerve cell damage, injury or compromise. The antibodies and fragments of the invention may be utilized to assess, quantitate, target and/or image neurons, in vitro or in vivo. The present antibodies including fragments thereof, and drugs that modulate the production or activity of the specific binding members, antibodies and/or their subunits may possess certain diagnostic applications and may for example, be utilized for the purpose of detecting and/or measuring conditions or diseases involving neuron compromise, degeneration, injury, damage or death. The present antibodies including fragments thereof possess certain diagnostic applications and may for example, be utilized for the purpose of detecting and/or measuring conditions or diseases involving cerebral ischemia including stroke or brain injury including traumatic brain injury. The labeled, including radiolabelled, antibodies and fragments thereof, are useful in in vitro diagnostics techniques and in in vivo radioimaging techniques and in radioimmunotherapy. In the instance of in vivo imaging, the antibodies or fragments of the present invention may be conjugated to an imaging agent rather than a radioisotope(s), including but not limited to a magnetic resonance image enhancing agent, wherein for instance an antibody molecule is loaded with a large number of paramagnetic ions through chelating groups. Examples of chelating groups include EDTA, porphyrins, polyamines crown ethers and polyoximes. Examples of paramagnetic ions include gadolinium, iron, manganese, rhenium, europium, lanthanium, holmium and ferbium. In a further aspect of the invention, radiolabelled antibodies and fragments thereof, particularly radioimmunoconjugates, are useful in radioimmunotherapy, particularly as radiolabelled antibodies for cellular therapy. In a still further aspect, the radiolabelled specific binding members, particularly antibodies and fragments thereof, are useful in radioimmuno-guided surgery techniques, wherein they can identify and indicate the presence and/or location of compromised or damaged neurons or the sites of nerve injury, during or following surgery to target or remove such cells or to transplant or administer cells to those specific sites.
Radioimmunotherapy (RAIT) has entered the clinic and demonstrated efficacy using various antibody immunoconjugates. 131I labeled humanized anti-carcinoembryonic antigen (anti-CEA) antibody hMN-14 has been evaluated in colorectal cancer (Behr T M et al (2002) Cancer 94(4 Suppl):1373-81) and the same antibody with 90Y label has been assessed in medullary thyroid carcinoma (Stein R et al (2002) Cancer 94(1):51-61). Radioimmunotherapy using monoclonal antibodies has also been assessed and reported for non-Hodgkin's lymphoma and pancreatic cancer (Goldenberg D M (2001) Crit Rev Oncol Hematol 39(1-2):195-201; Gold D V et al (2001) Crit Rev Oncol Hematol 39 (1-2) 147-54). Radioimmunotherapy methods with particular antibodies are also described in U.S. Pat. Nos. 6,306,393 and 6,331,175. Radioimmunoguided surgery (RIGS) has also entered the clinic and demonstrated efficacy and usefulness, including using anti-CEA antibodies and antibodies directed against tumor-associated antigens (Kim J C et al (2002) Int J Cancer 97(4):542-7; Schneebaum S et al (2001) World J Surg 25(12):1495-8; Avital S et al (2000) Cancer 89(8):1692-8; McIntosh D G et al (1997) Cancer Biother Radiopharm 12 (4):287-94).
The radiolabelled antibodies and fragments thereof, are useful in in vitro diagnostics techniques and in in vivo radioimaging techniques. The antibodies and fragments thereof, particularly radioimmunoconjugates, are useful in radioimmunotherapy, particularly as radiolabelled antibodies for nerve injury repair, neurodegenerative recovery, cancer or CNS tumor therapy, or alternatively for ablation of damaged nerve tissue or neurons in certain instances. In an in vivo aspect, the antibody or neuron binding fragment thereof is labeled and administered to the animal prior to, during or after surgery or a surgical technique, including a stereotactic or minimally invasive technique, for the purpose of locating nerve injury or for assessing remaining damaged or injured neural tissue. In one such aspect, the radiolabelled specific binding members, particularly antibodies and fragments thereof, are useful in radioimmuno-guided surgery techniques, wherein they can identify and indicate the presence and/or location of compromised, damaged, injured or dying nerve cells or neurons or nervous tissue, prior to, during or following surgery to target, identify or remove such cells.
Diagnostic applications of the antibodies and fragments thereof of the invention include in vitro and in vivo applications well known and standard to the skilled artisan and based on the present description. Diagnostic assays and kits for in vitro assessment and evaluation of neurons or nervous tissue, may be utilized to diagnose, evaluate and monitor patient samples including those known to have or suspected of having neurological conditions or diseases where nerve cells are compromised, damaged or injured or determining the extent of cell death or injury or of a CNS tumor or cancer, including in a sample from a patient or subject. The assessment and evaluation of neurological disease status is also useful in determining the suitability of a patient for a clinical trial of a drug or for the administration of a particular neurotherapeutic or chemotherapeutic agent or an antibody of the present invention, including combinations thereof, versus a different agent or antibody.
The present invention includes an assay system which may be prepared in the form of a test kit for the quantitative analysis of the extent of the presence of, for instance, damaged, compromised or injured neurons or to quantitate neurons in a sample. The system or test kit may comprise a labeled component prepared by one of the radioactive and/or enzymatic techniques discussed herein, coupling a label to the antibody, and one or more additional immunochemical reagents, at least one of which is a free or immobilized components to be determined or their binding partner(s).
In a further embodiment of this invention, commercial test kits suitable for use by a medical specialist may be prepared based on the above to determine the status of neurons in a sample. In accordance with the testing techniques discussed above, one class of such kits will contain at least the labeled antibody or its binding partner, for instance an antibody specific thereto, and directions, of course, depending upon the method selected, e.g., “competitive,” “sandwich,” “DASP” and the like. The kits may also contain peripheral reagents such as buffers, stabilizers, etc.
Accordingly, a test kit may be prepared for the demonstration of the presence or determination of the status of neurons, comprising:
(a) a predetermined amount of at least one labeled immunochemically reactive component obtained by the direct or indirect attachment of the present antibody or fragment or a specific binding partner thereto, to a detectable label;
(b) other reagents; and
(c) directions for use of said kit.
A test kit may be prepared for the demonstration of the presence of nerve cell injury, damage or compromise comprising:
(a) a predetermined amount of at least one labeled immunochemically reactive component obtained by the direct or indirect attachment of the present antibody or a specific binding partner thereto, to a detectable label;
(b) other reagents; and
(c) directions for use of said kit.
The present invention further provides an isolated nucleic acid encoding an antibody, particularly a recombinant antibody, particularly a fully human antibody, of the present invention. Nucleic acid includes DNA and RNA. In a preferred aspect, the present invention provides a nucleic acid which codes for a polypeptide of the invention as defined above, including a polypeptide as set out in
The present invention also provides constructs in the form of plasmids, vectors, transcription or expression cassettes which comprise at least one polynucleotide as above. The present invention also provides a recombinant host cell which comprises one or more constructs as above. A nucleic acid encoding any antibody or fragment as provided forms an aspect of the present invention, as does a method of production of the specific binding member which method comprises expression from encoding nucleic acid therefor. Expression may conveniently be achieved by culturing under appropriate conditions recombinant host cells containing the nucleic acid. Following production by expression a specific binding member may be isolated and/or purified using any suitable technique, then used as appropriate.
Antibodies and encoding nucleic acid molecules and vectors according to the present invention may be provided isolated and/or purified, e.g. from their natural environment, in substantially pure or homogeneous form, or, in the case of nucleic acid, free or substantially free of nucleic acid or genes origin other than the sequence encoding a polypeptide with the required function. Nucleic acid according to the present invention may comprise DNA or RNA and may be wholly or partially synthetic.
Systems for cloning and expression of a polypeptide in a variety of different host cells are well known. Suitable host cells include bacteria, mammalian cells, yeast and baculovirus systems. Mammalian cell lines available in the art for expression of a heterologous polypeptide include Chinese hamster ovary cells, HeLa cells, baby hamster kidney cells, cancer cells, ovarian cancer cells and many others. A common, preferred bacterial host is E. coli. The expression of antibodies and antibody fragments in prokaryotic cells such as E. coli is well established in the art. Suitable vectors can be chosen or constructed, containing appropriate regulatory sequences, including promoter sequences, terminator sequences, polyadenylation sequences, enhancer sequences, marker genes and other sequences as appropriate. Vectors may be plasmids, viral e.g. ‘phage, or phagemid, as appropriate. For further details see, for example, Molecular Cloning: a Laboratory Manual: 2nd edition, Sambrook et al., 1989, Cold Spring Harbor Laboratory Press. Many known techniques and protocols for manipulation of nucleic acid, for example in preparation of nucleic acid constructs, mutagenesis, sequencing, introduction of DNA into cells and gene expression, and analysis of proteins, are described in detail in Short Protocols in Molecular Biology, Second Edition, Ausubel et al. eds., John Wiley & Sons, 1992. The disclosures of Sambrook et al. and Ausubel et al. are incorporated herein by reference.
Thus, a further aspect of the present invention provides a host cell containing nucleic acid as disclosed herein. A still further aspect provides a method comprising introducing such nucleic acid into a host cell. The introduction may employ any available technique. For eukaryotic cells, suitable techniques may include calcium phosphate transfection, DEAE-Dextran, electroporation, liposome-mediated transfection and transduction using retrovirus or other virus, e.g. vaccinia or, for insect cells, baculovirus. For bacterial cells, suitable techniques may include calcium chloride transformation, electroporation and transfection using bacteriophage. The introduction may be followed by causing or allowing expression from the nucleic acid, e.g. by culturing host cells under conditions for expression of the gene. The present invention also provides a method which comprises using a construct as stated above in an expression system in order to express a specific binding member or polypeptide as above.
Another feature of this invention is the expression of the DNA sequences disclosed herein. As is well known in the art, DNA sequences may be expressed by operatively linking them to an expression control sequence in an appropriate expression vector and employing that expression vector to transform an appropriate unicellular host. A wide variety of host/expression vector combinations may be employed in expressing the DNA sequences of this invention. Useful expression vectors, for example, may consist of segments of chromosomal, non-chromosomal and synthetic DNA sequences. Suitable vectors include derivatives of SV40 and known bacterial plasmids, e.g., E. coli plasmids col El, pCR1, pBR322, pMB9 and their derivatives, plasmids such as RP4; phage DNAs, e.g., the numerous derivatives of phage λ, e.g., NM989, and other phage DNA, e.g., M13 and filamentous single stranded phage DNA; yeast plasmids such as the 2u plasmid or derivatives thereof; vectors useful in eukaryotic cells, such as vectors useful in insect or mammalian cells; vectors derived from combinations of plasmids and phage DNAs, such as plasmids that have been modified to employ phage DNA or other expression control sequences; and the like. Any of a wide variety of expression control sequences—sequences that control the expression of a DNA sequence operatively linked to it—may be used in these vectors to express the DNA sequences of this invention. Such useful expression control sequences include, for example, the early or late promoters of SV40, CMV, vaccinia, polyoma or adenovirus, the lac system, the trp system, the TAC system, the TRC system, the LTR system, the major operator and promoter regions of phage λ, the control regions of fd coat protein, the promoter for 3-phosphoglycerate kinase or other glycolytic enzymes, the promoters of acid phosphatase (e.g., Pho5), the promoters of the yeast □-mating factors, and other sequences known to control the expression of genes of prokaryotic or eukaryotic cells or their viruses, and various combinations thereof.
A wide variety of unicellular host cells are also useful in expressing the DNA sequences of this invention. These hosts may include well known eukaryotic and prokaryotic hosts, such as strains of E. coli, Pseudomonas, Bacillus, Streptomyces, fungi such as yeasts, and animal cells, such as CHO, YB/20, NSO, SP2/0, RI.I, B-W and L-M cells, African Green Monkey kidney cells (e.g., COS 1, COS 7, BSC1, BSC40, and BMT10), insect cells (e.g., Sf9), and human cells and plant cells in tissue culture.
It will be understood that not all vectors, expression control sequences and hosts will function equally well to express the DNA sequences of this invention. Neither will all hosts function equally well with the same expression system. However, one skilled in the art will be able to select the proper vectors, expression control sequences, and hosts without undue experimentation to accomplish the desired expression without departing from the scope of this invention. In selecting an expression control sequence, a variety of factors will normally be considered. These include, for example, the relative strength of the system, its controllability, and its compatibility with the particular DNA sequence or gene to be expressed, particularly as regards potential secondary structures. Suitable unicellular hosts will be selected by consideration of, e.g., their compatibility with the chosen vector, their secretion characteristics, their ability to fold proteins correctly, and their fermentation requirements, as well as the toxicity to the host of the product encoded by the DNA sequences to be expressed, and the ease of purification of the expression products. Considering these and other factors a person skilled in the art will be able to construct a variety of vector/expression control sequence/host combinations that will express the DNA sequences of this invention on fermentation or in large scale animal culture.
A DNA sequence encoding an antibody or fragment thereof can be prepared synthetically rather than cloned. The DNA sequence can be designed with the appropriate codons for the specific binding member amino acid sequence. In general, one will select preferred codons for the intended host if the sequence will be used for expression. The complete sequence is assembled from overlapping oligonucleotides prepared by standard methods and assembled into a complete coding sequence. See, e.g., Edge, Nature, 292:756 (1981); Nambair et al., Science, 223:1299 (1984); Jay et al., J. Biol. Chem., 259:6311 (1984). Synthetic DNA sequences allow convenient construction of genes which will express specific binding member analogs or “muteins”. Alternatively, DNA encoding muteins can be made by site-directed mutagenesis of native specific binding member genes or cDNAs, and muteins can be made directly using conventional polypeptide synthesis.
The invention may be better understood by reference to the following non-limiting Examples, which are provided as exemplary of the invention. The following examples are presented in order to more fully illustrate the preferred embodiments of the invention and should in no way be construed, however, as limiting the broad scope of the invention.
The invention may be better understood by reference to the following non-limiting Examples, which are provided as exemplary of the invention. The following examples are presented in order to more fully illustrate the preferred embodiments of the invention and should in no way be construed, however, as limiting the broad scope of the invention.
Natural serum human IgMs that bind to neurons were identified by screening the Mayo Clinic serum bank, which contains over 140,000 samples collected over 45 years, for candidates with a high monoclonal spike of IgG or IgM (greater than 10 mg/ml in the blood) and then testing serum for antibody binding to slices of live brain cortex and cerebellum (31). Such IgMs were then purified from positive samples and further tested for 1) binding to the surface of isolated primary neurons 2) as substrates for the support of neurite extension 3) the ability to protect neurons from apoptosis in the face of stressor molecules. This screening protocol is based on that used to identify human IgMs that bind to oligodendrocytes and promote remyelination in models of MS (22, and as described in WO 0185797). The recognition of the surface of appropriate tissues or cells appears to be an important defining characteristic of therapeutic IgMs.
Two novel, distinct serum-derived human neuron binding IgMs have been identified (sHIgM12 and sHIgM42). Certain characteristics of these serum-derived antibodies are listed in TABLE 1. Serum derived sHIgM12 and sHIgM42 have been shown initially in vitro to support neurite extension as well as the potent substrate laminin and to override the neurite outgrowth inhibition of CNS myelin (23).
Further studies have shown that serum-derived sHIgM12 improves spontaneous function in TMEV infected mice, as assessed by mean hourly spontaneous nocturnal activity in mice (21). In contrast to previously identified IgM NatAbs (sHIgM22 and sHIgM46), neither sHIgM12 nor sHIgM42 promote spinal cord remyelination.
Often, autoantibodies are thought of as pathogenic. In contrast, as demonstrated herein, the autoantibodies to neurons (sHIgM12 and sHIgM42 and recombinant antibodies based thereon) do not kill neurons. Instead these IgMs protect neurons from death, promote neurite extension, increase NAA in vivo, protect axons in vivo in the TMEV model, and improve nocturnal spontaneous function of TMEV diseased mice.
The neuron binding antibodies IgM12 and IgM42 target neurons in CNS lesions and applicable to reverse neuronal loss and/or ameliorate the effects of neuronal injury or disease. Neuron-binding human IgMs represent a new class of therapeutics with unique application for various diseases and conditions involving neurodegeneration, neuron injury or neuron death. Such diseases include without limitation, MS, spinal cord injury, ALS, Alzheimer's Disease, traumatic brain injury, cerebro-vascular events or stroke. These human IgMs have been minimally antigenic when administered systemically in animals.
Identification and Characterization of Human IgMs that Bind to the Surface of Multiple Types of Living Neurons:
Serum samples with a high concentrations of IgG or IgM (>10 mg/ml) were screened for Ab binding to neuronal layers in live CNS tissue slices (cortex and cerebellum). Of 152 sera tested, 17 human sera were positive on tissue slices (23).
Antibodies sHIgM12 and sHIgM42 bind to the surface of a wide variety of neurons that co-label with neuronal markers neurofilament or β III tubulin. These include cerebellar granule cells (23), cortical neurons, hippocampal neurons, neurons from human temporal lobe biopsy (
The present data indicate that the binding of sHIgM12 or sHIgM42 to the surface of neurons is carbohydrate-dependent. Sialidase treatment of neurons in culture eliminated the binding of both human IgMs to the cell surface, whereas blocking sphingolipid synthesis with Fumonisin B1 or removing GPI-linked proteins with PIPLC did not eliminate IgM binding (23). Gangliosides are candidates for antigens of these human IgMs. In co-labeling experiments, rHIgM12 co-localizes with GM1 on the neuronal membrane (see Example 11 and
Although they share certain functional characteristics such as eliciting neurite outgrowth, sHIgM12 and sHIgM42 do demonstrate differences and are each unique antibodies. This is evident in binding and immunofluorescence studies; they label the surface of cerebellar granule cells in distinct patterns. In immunofluorescence studies of rat cerebellar granule cells in culture, the patterns of neuronal membrane labeling by use of these two antibodies are distinct (
Remyelination-promoting human IgMs have been shown to protect oligodendrocytes in culture from peroxide-induced activation of caspase 3 (33), a marker of active apoptosis. As set forth herein, sHIgM12 or sHIgM42, were evaluated in analogous protocols. The sHIgM12 or sHIgM42, respectively, and peroxide were added together to cultures of primary mouse cortical neurons and the degree of caspase 3 activation assayed 24 hr later (
Treatment of cultured neurons with rHIgM12 resulted in protection of 80% of caspase 3 activation. Treatment of neurons with sHIgM42 was protective also with approximately of 40% of caspase 3 activation. These results were significantly different (P<0.01) compared to a control human IgM, which resulted in less than 10% protection from caspase 3 activation.
Thus, neuron-binding sHIgM12 or sHIgM42 protected cortical neurons from cell death induced by peroxide. Thus, when an inducer or agent of nerve cell damage (or death) was provided, IgM12 and IgM42 independently and significantly prevented the damage (or death) from occurring.
Two recombinant forms of sHIgM12 have been constructed. Each used the same expression vector as was previously utilized for recombinant IgM22 antibody (rHIgM22) for the heavy and light chains (22, 28, WO0185797). The vector includes a selectable dHfR gene expressed under the control of the SV40 promoter. A partially human recombinant IgM12 antibody form with a mouse J chain was initially constructed as follows, thereafter antibody produced in human/mouse hybridoma line F3B6 cells.
The recombinant IgM12 antibody (PAD12) vector construction was performed by inserting the heavy chain variable region cDNA with a leader sequence from the nucleotide database and complete light chain cDNA with attached leader sequence from the nucleotide database in a manner similar to that described previously (6), using the primers described below. The vector is depicted in
Primers used to make rHIgM12VH and splice it by overlap extension (Horton R M et al (1989) Gene 77:61-68) to a leader sequence with an intron (lower case letters) from data base (M29812) are as follows:
TCC GGA CGG TCC GGG A
Primers used to make rHIgM12Vk and splice it by overlap extension (soe) to the leader sequence from the data base (lower case letters, accession X59312) are as follows:
The vector with the synthetic antibody genes was introduced into F3B6 hybridoma cells by electroporation and methotrexate (MTX) amplification was performed as described previously (6).
Briefly, 8 million F3B6 mouse/human heterohybridoma cells (American Type Culture Collection: ATCC) were incubated with 10 μg PAD12 vector linearized with Bgl II for 10 min in 800 μl serum free media at which time they were electroporated at 0.2 V in a Biorad Gene Pulser™ (Biorad, Hercules, Calif., USA). Following a 10-min incubation on ice, the cells were diluted to 24 ml in RPMI-1640 containing 10% fetal calf serum (FC) (Gibco, Carlsbad, Calif., USA), plated in a 24-well plate and incubated at 37° C.; 48 h later, the cells containing vector were selected using 1 μM methotrexate (Calbiochem, La Jolla, Calif., USA). Following a 2-week incubation period, colonies were picked to a new plate and allowed to grow until confluent. At this point, the supernatant was harvested and assayed by enzyme linked immunosorbent assay (ELISA) for the presence of human IgM. Positive colonies were selected further over the course of 2 months with increasing doses of methotrexate ranging from 1 μM to 200 μM. In this manner, cells were generated that produced greater than 10 μg/ml IgM.
The first recombinant antibody constructed as above is not fully human. To generate a completely human form, CHO cells (GibcoBRL cat #11619) were co-transfected with vector encoding the recombinant heavy and light chain under control of an E1A promoter and a construct that expresses the human J chain in pCI (Promega). The cells were selected with increasing doses of methotrexate in a 50/50 mixture of PowerCho1 and IMDM with 10% cosmic clone and the two clones that produced the most antibody as measured by ELISA were sub-cloned. The sub-clones were expanded and vials were frozen down. Both recombinant IgM12 forms maintain the neuron binding and in vivo efficacy character of the serum isolated IgM, but have a shorter half life in mice (which may be due to differences in glycosylation).
A similar and comparable procedure was utilized to construct recombinant HIgM42 antibody in the comparable vector. The sequence of the heavy and light chain of human IgM42 antibody, with variable and constant regions noted, is shown in
In view of the fact that rHIgM12 protected primary neurons in culture, and that disability in the TMEV model of multiple sclerosis (MS) correlates with axon loss (2), treatment of TMEV infected mice with rHIgM12 was used to evaluate the ability to slow the progression of neurologic deficits.
Groups of 5 mice at 90 days post TMEV infection, the point at which axons begin to be lost, were treated with a single 100 μg dose of rHIgM12 or a control human IgM. Five infected mice were randomly selected for each group and pretreatment functional recordings used to be certain that the baseline activity was not different between groups. Mice were followed as groups for 3 consecutive days over several weeks using activity boxes (34, 35). Changes in nocturnal behavior are sensitive measures of neurologic deficit in TMEV-mediated disease. Activity boxes are clear acrylic boxes with opposed infrared beams creating a grid across the enclosure that records all horizontal and vertical movements. The sensitivity of the assay reflects the ability to measure rearing and walking. In TMEV-infected mice the hind limbs become stiff and rearing is reduced. However, spontaneous walking about the cage is not as severely affected. It is easier for mice with stiff hind limbs to walk than to rear, and even mice with advanced disease can be extremely active during the night.
Each treatment group was randomly assembled and housed in activity boxes for 72 hr prior to treatment, and then for 72 hr each week after treatment. The mean hourly beam breaks were calculated for horizontal and vertical activity over the 12 hr from 6 pm to 6 am over the 72 hr analysis period. There were no differences between treatment groups in daytime horizontal or vertical activity, which was typically below 600 breaks/hr as mice sleep. However, an increase in spontaneous nocturnal horizontal activity compared to their pre-treatment baseline was recorded in the rHIgM12 treated group (P<0.01, weeks 3 through 7) (
In contrast to the effect seen with serum-derived sHIgM12, and now also recombinant antibody rIgM12, in a similar study the human antibody sHIgM42 did not alter nocturnal activity of TMEV infected mice under the same conditions. Alternative dosing parameters for sHIgM42 in the same assay format produce different and more positive results on nocturnal activity.
One possible explanation for the improvement in function is that the effective IgMs interfere with virus loads which results in less disease. This does not appear to be the explanation, however. Mice with chronic TMEV disease were treated with a single dose of rHIgM12, sHIgM42 or control IgMs, the brain and spinal cord harvested 5 wk later and then the level of TMEV RNA genomic transcripts were measured by PCR with a probe to ViralProtein2. Viral transcripts were not different across groups (P<0.01) (data not shown).
NAA is a metabolite associated with neuron function (36, 37). NAA is the second most abundant amino acid in brain and is almost exclusively restricted to neurons. The preservation of NM levels at the brain stem is a measure of overall spinal cord axon health validated by our group using the TMEV mouse model (8). When axons at lower levels of the spinal cord are damaged, cells in the brain stem die, reducing NM. NM levels measured by MRS reflects primarily neuron density. NAA is expressed in other neural cells, but the primary expression of NM is in neurons. Studies of the MRS profile of purified CNS cells indicate that NM signal amplitude is predominate in neurons, whereas the NM signal amplitude of oligodendrocytes or astrocytes were 5% and 10% of the neuron signal, respectively (38).
To further evaluate the ability of sHIgM12 and IgM42 to improve activity in mice by preserving axon function, we used a non-invasive imaging assay and traditional morphology to assess spinal cord axons. Retrograde tracing was used to demonstrate spinal cord axon dysfunction following demyelination in TMEV-mediated disease (5). A dramatic reduction of retrograde label from the thoracic level axons to brain stem nucleic was measured. The brainstem is where many of the cell bodies reside that project long axon tracts along the length of the spinal cord. Thereafter N-acetyl aspartate (NM) levels at the brain stem were assessed by magnetic resonance spectroscopy (MRS) in TMEV infected mice (
We observed a reduction in brainstem NM over time in mice with TMEV-induced disease (
After the last MRS collection, axons were systematically sampled from 6 areas of normal-appearing white matter within a cross section of spinal cord at the T6 level. This level was chosen because this provided a global representation of the axon loss from multiple, randomly distributed demyelinated lesions throughout the spinal cord (39). We found there were 30.5% fewer axons in 270 day TMEV infected SJL mice compared to uninfected controls (p<0.001). A positive correlation was found to exist between brain stem NAA levels and axon counts at the T6 level of the spinal cord (r=0.823) (8).
The ability of human neuron-binding IgMs to alter NM levels or axon counts in TMEV infected mice was evaluated. It was found that when TMEV-infected mice at the onset of spinal cord axon drop out (90 days post infection) were treated with a single 100 μg dose of sHIgM12 or of sHIgM42 neuron binding IgM, myelinated axon density in the normal white matter of the thoracic spinal cord was greater when measured 10 wk later.
Groups of 10-15 mice at 90 days post-infection were treated with a single 100 μg dose of sHIgM12, sHIgM42, control human IgM or saline (
NAA levels of the sHIgM12 and sHIgM42 treated groups increased to 9.13 and 9.3 mM, respectively, each of which was well below the 12.0 mM levels of uninfected mice. When axons at the T6 level were compared across treatment groups (TABLE 2), mice treated with sHIgM12 or sHIgM42 contained more axons than the saline treated group (17,303 and 17,771 axons compared to 15,198 axons, P=0.008 and P<0.001), but fewer than the number of axons counted in uninfected mice (21,284 axons).
These results indicated that each of the sHIgM12 and rHIgM12 antibodies improved function by preservation of axons, as evidenced in the TMEV model. Although the sHIgM42 antibody preserved axons in the TMEV model, demonstrable changes in the nocturnal activity assessment were not observed in the initial test. Following dose-ranging studies it is found that sHIgM42 also achieves heightened activity in the nocturnal activity test.
The use of brainstem MRS to assess axon status in mouse models of spinal cord disease further validates the present invention; accordingly NAA in the brain stem serves as an excellent endpoint for clinical trial use of these human antibodies.
sHIgM42 and sHIgM12-treated mice with improved NM levels also contained more axons in the mid-thoracic spinal cord. Groups of 10-15 TMEV-infected SJL mice were treated with a single 100 μg dose of rHIgM22, sHIgM42, sHIgM12, control sHIgM39 and saline at 90 days post infection. Ten weeks after treatment, spinal cords were removed and a mid-thoracic section stained with PPD to visualize myelin. Six areas encompassing 400,000 μm2 of white matter were sampled from each mouse and the number of myelinated axons counted (1). The average of absolute number of myelinated axons per T6 cross section ±SEM is listed in Table 2.
Several human IgMs (e.g., sHIgM22 and sHIgM46) that bind to oligodendrocytes and promote remyelination (22, 40, 41) have been identified. As shown below, neuron binding IgMs improve neuron numbers and function yet without obvious remyelination. Without being bound by theory, the mechanism of action is understood to be due to direct activation of axons (protection, neurite extension) and/or by activating the innate or adaptive immune system to secrete factors that protect neurons. The results presented above clearly demonstrate that the antibodies have a direct effect on axons/neurons. Within the same spinal cords in which sHIgM12 and sHIgM42 mediated axon preservation and/or regrowth was measured, overall demyelination, remyelination and inflammation were not different across treatment groups (
These attributes were quantitated by grading the quadrants of 10 spinal cord cross sections (6) representing samples along the length of the spinal cord. The rHIgM22 treated group (positive control) showed the expected increase in remyelination, whereas sHIgM12 and sHIgM42 treated mice contained little spinal cord remyelination. Accordingly, neurologic deficits in the TMEV model were improved (e.g., IgM12) without the requirement of significant remyelination; moreover, remyelination is not necessary for axon preservation and/or regrowth within the time frame examined.
To determine the half life of human IgMs, rHIgM12 (with human J chain) and sHIgM42, 100 μg of rHIgM12 that contains the human J chain or 100 μg sHIgM42 in 200 μl of saline was injected into the tail veins of normal CD-1 mice (
For rHIgM12 the half life between the first collection at 15 min and the collection at 8 hr was 3.8 hr. For sHIgM42 the half life between the first collection at 15 min and the collection at 24 hr was 20.5 hr. These values bracket the half life of the remyelination-promoting rHIgM22 which has a half life in mice of 15 hr (29) and in rabbits of 90 hr. Half life was calculated using the formulas kelm=(ln(cpeak)−ln(clow)/tinterval and t1/2=0.693/kelm.
It has been often accepted that IgMs with a molecular weight of close to 1 million may be too large to cross the blood brain barrier (BBB) from the circulation and thereby enter the CNS (42, 43). There is certain evidence, however, that some IgMs do cross the BBB.
Tissue distribution of 35S labeled rHIgM12 in normal and TMEV-infected SJL mice was measured (
It is also found that rHIgM12 (both with and without human J chain) and sHIgM42 are able to cross the BBB in normal and SAMP8 mice, which model Alzheimer's disease. Accordingly, 125I labeled human IgMs are injected i.v. and brains collected two hr later. Each of these antibodies accumulates in the brains of normal and diseased mice. These antibodies also reverse cognitive impairment in the mouse model of Alzheimer's disease whether the IgM is delivered by intracerebral injection or i.v.
The study of the isotopically labeled remyelination promoting mouse IgM, SCH94.03, by Hunter (44) used autoradiography to demonstrate radiolabel localized in vivo in the spinal cord of TMEV infected mice, specifically to cells that were ultrastructurally identified as oligodendrocytes. Similar autoradiography studies with 35S rHIgM12 have been performed. Using traditional immunocytochemistry, we have detected neuron binding human IgMs within spinal cord lesions (
Accordingly, 1.0 mg of rHIgM12 (with human J chain), sHIgM42 or a commercial control human IgM (Jackson Immuno Research) were administered intraperitoneally to TMEV infected mice with chronic demyelination. Four hours later mice were perfused with paraformaldehyde, the spinal cords frozen sectioned longitudinally and immunostained for the presence of human IgM mu chain. In mice receiving rHIgM12 or sHIgM42 human mu chain was localized in demyelinated lesions in parallel tracts, suggesting axon fibers. The control human IgM was not found within lesions or in the non-lesioned cord. Thus, it was clear that neuron-binding human IgMs rHIgM12 or sHIgM42 cross the BBB in TMEV infected mice.
Adjacent spinal cord sections were then immunolabeled with anti-neurofilament (NF) Abs (SMI-32 and 34, Sternberger) followed by fluorescent secondary Abs anti-human mu chain-FITC and anti-mouse-TRITC. Confocal microscopy demonstrated that rHIgM12 and sHIgM42 co-localized to NF+ axons within lesions, in parallel tracks of fibers and as fiber bundles of axons cut on end (
To address concerns that administering autoreactive CNS binding IgMs to animals with active autoimmunity may exacerbate disease, the effects of rHIgM12 and sHIgM42 were tested in mice with EAE. Groups of 10 C57BL6 mice with MOG peptide-induced (200 μg) EAE were administered a single 100 μg dose of rHIgM12, sHIgM42, control human IgM or saline intravenously. Individual mice were treated at the time that their clinical score reached 1 (limp tail). Mice were then followed by an investigator blinded to the treatment groups who recorded weights and graded clinical scores every other day until mice reached 28 days post immunization or were moribund.
There were no differences between treatment groups in weights, or mean clinical scores (
Antibody sHIgM12, promoted neurite outgrowth in primary cultured cerebellar granule neurons. In the present example, using primary hippocampal neurons fully human (rHIgM12 having a human J chain) was found to promote axon formation. rHIgM12 binds to neuron membranes and induces clustering of cholesterol and ganglioside GM1.
Moreover, the membrane-bound rHIgM12 is distributed into two pools, one associated with lipid raft domains, and the other with the detergent insoluble pellet enriched in cytoskeleton. rHIgM12 aggregates colocalize over microtubules, but not over filamentous actin after detergent extraction. Coimmunoprecipitation studies demonstrated that rHIgM12 and β3-tubulin exist in a complex. These results indicate that rHIgM12 specifies axon formation by clustering membrane domains to signal the microtubule cytoskeleton.
Neurons develop axons though regulation of neurite outgrowth (Barnes and Polleux, 2009). The neuron cytoskeleton, which includes filamentous actin (F-actin) and microtubules, plays a crucial role in neurite growth and growth cone pathfinding.
Serum-derived antibody may not be suitable for larger scale studies, particularly if it cannot be produced in quantity and must be isolated for each use from the patient that produces the antibody, the generation of a recombinant form which demonstrates comparable activity and capability is advantageous. The present study demonstrated that recombinant and fully human IgM12 antibody (rHIgM12) promoted axon formation and thus drove neuronal polarization in cultured hippocampal neurons. The rHIgM12 clusters the neuronal membrane domains containing cholesterol and ganglioside GM1.
Sucrose density gradient fractionation indicated that neuronal membrane-bound rHIgM12 segregates into two pools, one associated with the detergent-resistant lighter fraction which contains caveolin-1, and the other with the cytoskeleton-enriched pellet. Detergent extraction of live neurons demonstrated that rHIgM12 is associated with microtubules. rHIgM12 also co-immunoprecipitated with β3-tubulin. Taken together, it is understood that rHIgM12 binds membrane domains associated with microtubules. When present as a substrate on a surface, rHIgM12 promotes microtubule anchoring on neuron membranes, facilitating neurite outgrowth and axon formation.
Recombinant Human IgM 12 (rHIgM12):
rHIgM12 was expressed in CHO cells (GibcoBRL, cat #11619). Plasmids expressing the heavy and light chain coding sequences for the predominant antibody expressed in the serum of Waldenstrom's macroglobulinemia patient 12 were transfected along with a human J chain transgene into CHO-S cells. The resulting CHO cells were selected with increasing doses of methotrexate and a stable clone that produced the antibody as measured by ELISA was subcloned and expanded. rHIgM12 antibody from culture supernatant was purified by chromatography to 97% as measured by HPLC analysis.
Cell Culture and Neurite Outgrowth Assay.
Primary hippocampal neurons were prepared from FVB mice. Embryonic day 15 hippocampal neurons were dissociated in trypsin-EDTA, plated on poly-D-lysine (PDL), PDL with laminin or rHIgM12 substrates coated on a thin layer of nitrocellulose membrane attached to glass coverslips and grown in Neurobasal Media containing 2% (v/v) of B27. Neurite outgrowth was assayed 12 hr after neurons were seeded. The neurons were fixed with 4% paraformaldehyde and stained with anti β3-tubulin antibody. Filamentous actin (F-actin) was labeled with Texas-Red phalloidin, and nuclei with DAPI. Neurite length was measured using Neuron J software, processed with Excel (Microsoft) and analyzed statistically with Prism (GraphPad). A Stage-3 neuron was defined as a neuron with multiple neurites in which the longest neurite (Dotti et al., 1988), determined as an axon by Tau1 staining, was at least two times the length of the second longest neurite. Tau1 was asymmetrically enriched in the distal part of the axon. In contrast, Stage-2 neurons had multiple symmetric neurites.
Immunostaining, Immunoprecipitation and Sucrose Density Gradient Fractionation of Primary Cultured Neurons:
One to three days in vitro (DIV) cultured hippocampal neurons were permeabilized with 0.2% Triton X-100 after fixation with 4% paraformaldehyde followed by immunostaining. Images were collected using an Olympus upright microscope and processed using Photoshop (Adobe). rHIgM12 distribution was determined by ultracentrifugation in non-continuous sucrose gradient. Briefly, rHIgM12 was allowed to bind to live DIV7 cortical neurons at 4° C. for 30 min then lysed in ice-cold lysis buffer (50 mM Tris.HCl, pH 7.4, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100 and protease inhibitor cocktail) for 30 min. The neuronal lysates were mixed with an equal volume of 100% (w/v) sucrose. The mixture was transferred to a centrifuge tube, and 8 ml of 35% sucrose and 3.5 ml of 5% sucrose were overlaid sequentially. After centrifugation at 2×105 g for 20 h at 4° C., six fractions (2 ml of each) were collected from the top of the gradient. Each fraction and the pellet were dissolved in SDS-sample buffer and subjected to western blotting.
For co-immunoprecipitation of rHIgM12 with cytoskeleton protein, DIV7 live cortical neurons were treated with rHIgM12 at 4° C. for 30 min and lysed in lysis buffer containing 0.5% NP-40. rHIgM12 was captured by protein L-agarose beads, and β3-tubulin by protein G-resin (Thermo). For double-labeling, live neurons were stained with rHIgM12 on ice and permeabilized with 0.2% Triton X-100 after fixation. Live neuron extraction and fixation was performed in buffer containing 60 mM Pipes, 25 mM Hepes, 5 mM EGTA, 1 mM MgCl2, 4% paraformaldehyde and 0.1% Triton X-100.
Antibodies and Other Reagents in this Example:
Anti-β3-tubulin (Promega); anti-actin, EDTA, poly-D-lysine, methyl-β-cyclodextrin and filipin (Sigma); anti-Tau1, anti-caveolin-1 and anti-transferrin receptor (Millipore); Texas Red-phalloidin, cholera toxin B, Neurobasal Medium and B27 (Invitrogen); protease inhibitor tablet (Roche).
Recombinant Human IgM, rHIgM12, Promoted Axon Formation:
To further understand the effect of the IgM on neuron differentiation and the underlying molecular mechanisms, neurite outgrowth assays were carried out with cultured hippocampal neurons using a recombinant rHIgM12. Hippocampal neurons undergo three stages of differentiation to form an axon (Dotti et al., 1988). Multiple processes initiate from the cell body. One of the fast growing neurites differentiates into the axon, the others into dendrites later, which can be identified by the differential distribution of Tau1 and MAP2 respectively (Lewis et al., 1989; (Kanai and Hirokawa, 1995). We found that rHIgM12, when presented as a substrate, substantially promoted neuron differentiation. Within 12 hours after plating, the hippocampal neurons growing on rHIgM12 developed multiple neurites, and one of them was much longer compared to the neighboring neurites. In contrast, neurons plated on poly-D-lysine (PDL) had multiple symmetric neurites (
After measuring neurite length, we found that neurons plated on rHIgM12 (n=86) compared to PDL (n=74) had significantly longer total neurite length (195.8 μm vs. 150.7 μm, p=0.0056) (
The characteristic feature of neuron differentiation is polarized axon outgrowth and segregation from dendrites. We observed that rHIgM12 promoted neurite extension, with one significantly longer neurite. To further verify that these longest neurites from the stage 3 neurons developed into axons, the hippocampal neurons plated on different substrates were stained with anti-tau1 and MAP2 antibodies (
Comparing the tau1 intensity from neurons grown on PDL (
rHIgM12 Induced Neuronal Membrane Microdomain Clustering
Hippocampal neurons growing on rHIgM12 as a substrate showed enhanced differentiation (
rHIgM12 Bound Lipid Rafts
Biochemical studies based on nonionic detergent extraction in cold conditions have been used to demonstrate the existence of lipid rafts which contain cholesterol and glycosphingolipid (Chichili and Rodgers, 2009). However, there is limited morphological information about lipid rafts because the nanoscale size is beyond the resolution of the light microscope (Lingwood and Simons, 2010). The observation that rHIgM12 induces membrane clustering and colocalizes with cholesterol- and GM1-containing membrane domains (
Since neuronal membranes are enriched in cholesterol and glycosphingolipid, which have higher melting temperatures (Tm) (Samsonov et al., 2001), decreasing the membrane temperature below Tm may facilitate visualization of lipid raft and its associated molecules which are more dynamic at 37° C. To test this hypothesis, live neurons were cooled down to 4° C., followed by rHIgM12 staining. In contrast to neurons fixed at 37° C. where rHIgM12 bound evenly (
We took advantage of the fact that lipid rafts are cholesterol dependent membrane domains and that cholesterol depletion disrupts their structure (Chichili and Rodgers, 2009). Cultured hippocampal neurons were first treated with methyl-β-cyclodextrin (M3CD) to deplete cholesterol (Ko et al., 2005) and then cooled down to 4° C., followed by rHIgM12 and CTB staining after fixation. rHIgM12 bound to punctate structures in neuronal membranes after cholesterol depletion, and colocalized with CTB-labeled GM1 (
We further tested the hypothesis that rHIgM12 binds to lipid rafts. Because lipid rafts localize within the nonionic detergent-resistant membranes (DRM) at cold temperature (Samsonov et al., 2001), the localization of rHIgM12 was analyzed in cortical neuron lysates prepared at 4° C. Blotting the neuronal lysates with anti-human secondary IgM antibody revealed that membrane-bound rHIgM12 was found in both the pellet and the supernatant, while the non-neuron-binding control IgM antibody was found in only the wash eluates (
In a second experiment, cortical neurons were first labeled with rHIgM12, then fractionated by sucrose density gradient at 4° C. Blotting of different fractions indicated that rHIgM12 localized to the lighter fraction which also contained caveolin-1, a lipid raft marker, but not to the transferrin receptor-enriched non-raft fraction (
rHIgM12 Associated with Microtubules
Our data showed that aggregated rHIgM12 localized to the regions such as the cell body, neurite shaft and growth cone central domain (
We found that rHIgM12 colocalized with GM1 (
The data herein demonstrated that a fully human recombinant IgM, rHIgM12, drove neuron polarization by promoting axon outgrowth in primary cultured hippocampal neurons when presented as a substrate (
The foregoing indicates that rHIgM12 binds to and interacts with lipid raft microdomains, and further indicates that rHIgM12-associated raft domains convey signaling to microtubules. As a result, rHIgM12 mediates microtubule stabilization, which drives axon outgrowth. This example demonstrated that rHIgM12 selectively promotes axon outgrowth of primary hippocampal neurons (
Recently, we showed that the human sera-derived IgM, sHIgM12, improved neurological function of a multiple sclerosis animal model which develops extensive axonal degeneration and loss (Rodriguez et al., 2009). These studies support the concept that HIgM12 exerts its function by encouraging axon growth.
Neurons specify axons through a controlled intrinsic program which regulates neurite extension. A developing neuron initiates multiple neurites. One of the neurites differentiates into the axon, the others dendrites. The neighboring neurites compete with each other. The longest neurite, which also has the fastest extension rate, first breaks the symmetric neurite extension to develop into an axon, whereas the other neurites extend much slower and develop into dendrites later (Dotti et al., 1988; Goslin and Banker, 1989). F-actin and microtubules are the two major cytoskeletons which are involved in neurite extension and axon formation. Our understanding of axon specification has been evolving. F-actin, which mainly localizes to the growth cone periphery, was regarded to play a major role. Microtubules, which dominate the neurite shaft and are confined to the growth cone central domain, were thought to be secondary to F-actin. Recently, microtubules were found to also play a critical role in axon growth. Microtubules are capable of dynamically exploring the growth cone actin meshwork. Microtubule stabilization is sufficient to induce axon formation (Witte and Bradke, 2008).
Our results, that rHIgM12 and β3-tubulin co-immunoprecipitated, that rHIgM12 colocalized with microtubules and that rHIgM12 was present in the pellet after detergent extraction, not only support microtubules as a central player. In addition, this data provided the first evidence in the art that microtubules directly interact with neuron membranes. These findings support the concept that rHIgM12 interacts with or binds to a trans-membrane cascade which conveys extracellular signal to microtubules. The dynamic property of microtubules to grow and retract, for example in the growth cones, enables them to drive neuron membrane movement (Dent and Kalil, 2001). The stabilized microtubules anchor the neuron membranes. The existence of dynamic and stabilized microtubules and/or the transition between these two states orchestrate the process of neurite outgrowth to specify an axon. Accordingly, IgM12 enhances axon extension by effecting microtubule stability.
Lipids and proteins are continually incorporated into cell membranes which are then partitioned into microdomains, the so-called lipid rafts. Membrane rafts are generally defined as nano scale (10-200 nm), heterogeneous, and dynamic membrane compartments enriched with sterol and sphingolipid (Lingwood and Simons).
We propose that rHIgM12 binds to lipid rafts. First, we observed that rHIgM12 aggregated on neuron membranes and induced the clustering of cholesterol or ganglioside, GM1 (
Signal cascades, from the outer leaflet of neuron membranes to the intracellular cytoskeleton, are central to axon specification. rHIgM12 aggregates were distributed to the neurite shaft and the growth cone central domain (
These results demonstrated that some of rHIgM12 associates with cytoskeletal component(s), possibly microtubules. The finding that rHIgM12, which associated with “detergent-soluble” molecules in the supernatant (
The rHIgM12-bound molecules in the lipid raft domains may be incorporated constantly into the cytoskeletons during the process of neurite outgrowth and axon extension. This hypothesis is supported by the findings that, at the growth cone region, rHIgM12 aggregated in the central domain (
Whether F-actin is involved in rHIgM12-induced signaling is not clear. A number of lines of evidences indicate that both actin and actin-binding proteins are associated with lipid rafts (Levitan and Gooch, 2007). Actin filaments and microtubules actively interact in coordinated cell movement (Rodriguez et al., 2003) which also include neurons. Thus it is likely that actin also plays a role in rHIgM12-induced signaling. Along with β3-tubulin, a small amount of actin was pulled down by rHIgM12 (
However, rHIgM12-labeled puncta remained in the very edge of the growth cone, whereas F-actin networks shrunk from the growth cone periphery when the neurons were treated at 4° C. (
We conclude that the human IgM rHIgM12 binds to and reorganizes lipid rafts, and that microtubules are one of the downstream targets. rHIgM12 promotes axon extension only when presented as substrate. As a substrate, rHIgM12 was immobilized and constrained in its interaction with the neuronal membrane. The immobilized rHIgM12 may have created a gradient of signals across the neuronal membranes as frequently observed in morphogen-induced signaling (Schmitt et al., 2006). In contrast, bath application of rHIgM12 may only facilitate random lipid raft clustering (
Axon protection and repair following spinal cord injury (SCI) holds great potential as an effective strategy to prevent motor neuron loss and permanent disability. Neuron protection has been achieved using targeted trophic factors for preventing damage and promoting repair of axons following injury. These molecules were predominantly identified using selection strategies based upon in vitro systems that focused upon targeting specific small molecule neurotrophic factors.
Natural autoreactive monoclonal antibodies have demonstrated beneficial biological functions in CNS cells using multiple models of injury and disease. Antibody-mediated promotion of neuron survival, axon regeneration and functional recovery has been demonstrated in vivo using the mouse monoclonal IgM, IN-1 (Bregman 1995; Caroni and Schwab 1988). Similar results were obtained using immunization of spinal cord homogenate (SCH) prior to CNS damage (Ellezam 2003; Huang 1999).
Based on our data from neuron binding human antibodies including IgM12 and the remyelinating antibody IgM22, it is disclosed that human monoclonal antibody interactions that protect axons from damage by promoting neuron survival and function, and beneficial for treating CNS injury and/or disease such as SCI, are dependent upon surface plasma membrane protein-lipid bilayer interactions under pathological/physiological conditions.
Human antibodies that promote neuron survival following nerve injury or damage (e.g. in SCI) or that protect neurons from injury or death, in each instance resulting in preservation of neurological function, are assessed, characterized and/or identified using technologies that maintain the pathological/physiological surface plasma membrane protein-lipid bilayers.
In this study, we determine surface binding interaction kinetics of the human monoclonal antibodies using protein-lipid bilayer surface plasmon resonance (SPR) sensors. Human monoclonal antibodies are characterized or identified using binding in spinal cord lesions of ex vivo tissue sections from rodents following spinal cord injury. Next, a rodent spinal cord crush injury model is used to further assess the ability of human antibodies to promote neuron survival, neurite extension or remyelination in vivo resulting in reduced pathology and improved neurologic function.
A novel SPR lipid bilayer sensor provides a rapid, label-free technology allowing characterization of surface protein-lipid binding kinetics and affinity of beneficial human IgM antibodies. This surface plasmon resonance (SPR) sensor technology was developed based on periodic nanopore arrays in metallic films combined with physiological planar lipid bilayer. The SPR technology has allowed rapid, label-free characterization of IgM antibody binding kinetics and affinity with relevant antigens.
Binding kinetics important to quantify small differences provide a rationale for selecting lead molecules during development and impact both the dosing and potency of a therapeutic molecule in vivo. SPR has become an accepted standard in industrial and academic settings, in which typically the molecular interaction between a pair of soluble binding partners are characterized. However, the technology is only beginning to be adapted to the needs of membrane-bound antigens. The gold substrate used in SPR sensing is not amenable to the formation of supported lipid membrane. Furthermore, membrane proteins in direct contact with the gold surface often lose their functionality. However, the development of novel nanopore-sensing architecture technology utilizing a thin gold film perforated with periodic arrays of nanopores has overcome these challenges (see, e.g.,
Membrane proteins can thereby be seamlessly integrated with the SPR sensing capability of gold nanopore arrays, maintaining their functionality in an environment that more closely mimics their natural state. Furthermore, membrane proteins integrated in the free-standing lipid bilayer can be easily accessed from both sides, making this approach more attractive for studying the mechanism by which antigen-antibody binding on the cell surface results in cell signaling (
This sensor platform characterizes surface protein-lipid binding kinetics and affinity of therapeutic IgM antibodies for testing in an animal model of spinal cord injury. We have extensively characterized certain IgM antibodies identified by binding to the “live” unfixed surface of cerebella tissue and cells in the CNS. These IgM antibodies (exemplified by IgM22 and IgM46) stimulated calcium flux in vitro and promoted remyelination in vivo. Based upon the same criteria, human antibodies have been identified by screening dysproteinemia serum bank samples at the Mayo Clinic. Additional human IgM antibodies (exemplified herein by IgM12 and IgM42) bind to the surface of neurons and promoted neurite outgrowth and prevented neuron death in vitro.
The neuron-binding antibodies exhibited specific immunoreactivity to specific CNS cells, structures, of injury and disease pathology using “live” unfixed cortical sections from the multiple mouse models of CNS injury and disease.
Natural human monoclonal antibodies have been shown to potentiate beneficial biological functions in CNS cells from multiple models of injury and disease. Human monoclonal antibodies bind to the surface of a wide variety of neurons in culture including cerebella, cortical, retinal ganglion and spinal cord neurons (for instance human antibodies IgM12 and IgM42). These antibodies induce neurite extension from CNS neurons (
The in vitro studies demonstrate binding of human monoclonal antibodies to surface plasma membrane of neurons. The characteristic binding is uniform at 0° C. while surface rearrangements form punctate structures at 15° C. (
Human monoclonal antibodies enter the spinal cord tissue and accumulate at sites of damage 4 hours after intravenous administration (
Human monoclonal antibodies have been identified using biological function assays to screen samples from the Mayo Clinic dysproteinemia serum bank. The serum samples, 115,000 collected over 40 years, contain high concentrations of monoclonal antibody from patients with monoclonal gammopathy. We have synthesized and tested recombinant human IgM 22, which has remyelination promoting activity in animal models (Mitsunaga 2002; Warrington 2000).
In one embodiment, the present Example generates GMP-quality monoclonal antibody useful for therapeutic, prognostic, diagnostic and/or prophylactic applications in conditions of nerve degeneration, nerve injury and/or damage, such as in human SCI or in demyelinating conditions that expose CNS neurons.
These studies further characterize and assess human IgM antibodies that promote neuron survival following traumatic SCI resulting in preservation of neurological function. Behavioral tests and morphological measurements of axon numbers following SCI are evaluated and differences between endogenous and antibody-mediated preservation of neurological function are determined. Treatments with the axon-protecting and axon-extending antibodies compared to antibody controls following SCI are utilized to characterize differences of neurological function preservation for specific antibody-mediated activities.
Membrane vesicles containing the plasma membrane protein-lipid bilayer are isolated from cells under physiological conditions. Nanopores of the SPR sensors are coated using microvesicle preparations of isolated neurons, glia, synaptosome and myelin membranes from normal CNS and spinal cord-injured tissues. Human monoclonal antibody serum samples and recombinant antibody samples are screened to determine binding kinetics for specific membrane types.
Human monoclonal antibodies that bind specifically to the surface plasma membrane of unfrozen unfixed “live” cells and tissues under physiological conditions as confirmed using SPR sensors are tested for specific binding using unfrozen, unfixed, “live” pathological tissues following SCI. Human monoclonal antibodies demonstrating binding to spinal cord lesions are furtherer characterized for applicability and activity in treatment following SCI in the rodent.
Protocol Design.
Compression injury is generated at the level of T9 in ten-week old female (18-22 g) C57BL/6J mice (Jackson Laboratories) using a modified aneurysm clip (FEJOTA mouse clip, 3 g or 8 g closing force). This model of SCI includes not only an initial impact, but also a persistent compression phase that promotes microcystic cavitation, axon degeneration, and robust astrogliosis, all hallmarks of human traumatic SCI (Joshi and Fehlings 2002). Behavioral tests using the Basso, Beattie, Bresnahan (BBB) Locomotor Rating Scale for rats and the Basso Mouse Scale (BMS) for Locomotion are determined following SCI to evaluate neurological deficits. The technique is depicted in
Live unfrozen, unfixed ex vivo tissue sections are then prepared from pathological lesions following spinal cord compression injury in rodents. Immunoreactivity of human IgM antibodies binding is screened using immunofluorescent (IF) staining of the sections maintained under physiological conditions.
Mice are treated acutely after a spinal cord compression injury with human antibodies, including rHIgM12 and sHIgM42 or rHIgM42, administered intraperitoneally. The ability of the human antibodies to promote axon preservation or tissue repair is measured. Behavioral tests using BBB and BMS scale are performed at regular intervals during the 5 week period following SCI. A single 0.5 mg dose of human antibody is administered i.p. to mice 30 min after SCI. Groups of mice (15 mice) receive human antibodies that promote neuron protection, neurite outgrowth, control human antibodies that do not bind to cells or control. Individual mice are housed overnight once a week in automated infrared activity boxes (Mikami et al. 2002) and spontaneous rearing, a measure of hind limb disability, and horizontal activity recorded (Accuscan Inc, Ohio). Traditional BBB scores are also collected weekly. Functional assessments are performed blinded.
Fluoro-gold and fast blue, 4 weeks after treatment, is injected into spinal cords of four mice at the lower thoracic level. One week later mice are perfused and the brains and spinal cords removed. Retrograde labeled cell bodies in the reticular, vestibular and red nuclei of the brain stem are counted across groups by fluorescent microscopy (Ure and Rodriguez 2002). The number of labeled cell bodies in the brain stem (vibratome section) reflects the level of functional axons throughout the spinal cord. Immunocytochemistry for β amyloid protein accumulation is performed on tissue cross sections taken every 1 mm along the spinal cord. The number of β amyloid aggregates in a section reflects impaired axon transport and axon dysfunction at that level.
Five weeks after injury, the remaining mice are perfused, with formaldehyde/gluteraldehyde and the spinal cords removed. Every other 1 mm block comprising the spinal cord lesion site is embedded in araldite plastic and sectioned (1 micron) and stained with paraphenylene to visualize preserved axons encircled by myelin. Area of lesion cross section, the preserved axon number and lesion immune cell infiltration are measured using Microsuite software (Olympus). Axon frequency is measured and compared across groups (McGavern et al. 2000; Rodriguez et al. 1987). All analyses are done on coded and blinded samples without knowledge of the experimental group. Preserved axons are expressed as the number of preserved axons/mm2 of lesion. Pair-wise comparison of data between experimental and control groups uses the Mann-Whitney Rank Sum test.
IgM antibodies are evaluated for their ability to promote functional improvement and augment the processes of remyelination, neurite outgrowth or both in a multiple sclerosis model in mice. The model involves the use of the picornavirus Theiler's Murine Encephalomyelitis Virus (TMEV) to induce persistent chronic, progressive demyelinating lesions of the CNS with characteristics similar to those found in human MS using a method similar to Warrington et al., 2007.
Female and male mice (approximately 8 w, SJL/J strain) are injected with Theiler's Murine Encephalomyelitis Virus (2×105 plaque forming units of Daniel's strain, 10 μL intracerebroventricularly). Mice are allowed to recover for a period of 6 months prior to randomization for treatment. Mice are then examined for coat condition, gait and righting reflex and randomly assigned to treatment groups (as indicated in treatment tables). Mice are then treated with a single intravenous injection of vehicle (normal saline) or recombinant human IgM antibody (0.025 to 2.5 mg/kg). Neurological function is monitored at 2 weeks, 1 month and 2 months after treatment.
Functional endpoints included scoring based on coat condition, gait, and Rotarod performance. For coat appearance, scoring is as follows: no disease (0); minimal coat changes (1); scruffy coat (2); incontinence and stained coat (3). Activity changes are quantitated in an automated activity box. Further, gait is analyzed using digital gait acquisition (DigiGait) using walking speeds >90 cm/s. Quantitative gait analysis endpoints include stance width and duration, stride length and frequency, paw angle as well as swing, braking and propulsion duration. Gait changes from baseline are quantitated. Rotarod performance (a measure of sensory and balance coordination is assessed by the ability of animal to walk on a rotating shaft measuring the motor in terms of speed and duration on the rotating shaft) is quantitated as the amount of time animals remain on the rotating apparatus over a series of trials.
At the completion of the experiment, animals are euthanized by overexposure to CO2. Brains and spinal cords are removed for evaluation of 1) degree of myelination (electron microscopic analysis of plastic-embedded paraformaldehyde/glutaraldehyde fixed osmicated tissue) and 2) neurite growth (assessment of the density of neurites by stereological assessment).
In the first embodiment, recombinant human antibodies are administered alone at three dose levels as indicated in Table 3A and Table 3B.
(*) X indicates improvement, X+ indicates more improvement, and X++ indicates even more improvement. The improvement score values are relative to the dosing of a given antibody. Thus an X+ is a greater improvement than X for that same Ab. The improvement X for one Ab is not necessarily the same as the X value for another Ab; the X+ value of one Ab is not necessarily the same as the X+ value of another Ab, and the X+++ value of one Ab is not necessarily the same as the X+++ value of another Ab.
In this example, the recombinant antibodies IgM12, IgM 42, IgM22 and IgM46 are each found to produce statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score (p<0.05) for each endpoint compared to vehicle treatment). Animals treated with vehicle yield a stable deficits in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score within 6 months of TMEV injury. A significant, dose-dependent change in sensorimotor endpoints over the dose range from 0.025-2.5 mg/kg, where X is an improvement, are found for each Ab, with an improvement X increase in sensorimotor endpoints at the low dose, a greater improvement X+ increase in sensorimotor endpoints with 0.25 mg/kg and an even greater improvement X+++ in sensorimotor endpoints at the 2.5 mg/kg dose. This trend is observed for group sizes of 12 animals powered at a level of 0.8 and an alpha level of 0.05. Thus, each of antibodies IgM12, IgM 42, IgM22 and IgM46 produce statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score (p<0.05 for each endpoint) compared to vehicle treatment. No distinctions in improvement are found based on gender.
In this Example, IgM12 and IgM42 are found to produce statistically significant, dose-dependent increases in neurite outgrowth in brain and spinal cord sections from TMEV infected mice as assessed by stereology compared to vehicle-treated controls. Significant, dose-dependent changes in neurite outgrowth over the dose range from 0.025-2.5 mg/kg, where X is an improvement, are found for each Ab, with an improvement X increase in neurite outgrowth at the low dose, a greater improvement X+ increase in neurite outgrowth with 0.25 mg/kg and an even greater increase in neurite outgrowth X+++ at the 2.5 mg/kg dose. This trend is observed for group sizes of 12 animals powered at a level of 0.8 and an alpha level of 0.05.
IgM22 and IgM46 are found to produce statistically significant, dose-dependent increases in remyelination in brain and spinal cord sections from TMEV infected mice as assessed by stereology compared to vehicle-treated controls. Significant, dose-dependent changes in remyelination over the dose range from 0.025-2.5 mg/kg, where X is an improvement, are found for each Ab, with an improvement X increase in remyelination at the low dose, a greater improvement X+ increase in remyelination with 0.25 mg/kg and an even greater increase in remyelination X+++ at the 2.5 mg/kg dose. This trend is observed for group sizes of 12 animals powered at a level of 0.8 and an alpha level of 0.05.
In this experiment, various combinations of fixed dose ratios of recombinant IgM antibodies are examined for improvement of neurological outcome in the TMEV model of MS as described in the previous example. Six months after exposure to TMEV, treatment with recombinant IgM combinations is initiated in mice. In this series of studies, mice are given either vehicle alone, or various combinations of IgMs, in a single intravenous administration (admixture). Sensorimotor endpoints are monitored as above. Myelination and neurite growth are evaluated to examine the changes produced by antibody combinations. The combinations under evaluation are shown in Table 4A and Table 4B.
(*)X indicates improvement, X+ indicates more improvement, and X++ indicates even more improvement. The improvement score values are relative to the dosing of a given antibody. Thus an X+ is a greater improvement than X for that same Ab. The improvement X for one Ab is not necessarily the same as the X value for another Ab; the X+ value of one Ab is not necessarily the same as the X+ value of another Ab, and the X+++ value of one Ab is not necessarily the same as the X+++ value of another Ab.
In this Example, the recombinant antibody combinations of IgM12+IgM42, IgM22+IgM46, IgM12+IgM22, IgM12+IgM46, IgM42+IgM22, and IgM42+IgM46 produce statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment). No distinctions in improvement are found based on gender.
Further, the degree of sensorimotor endpoint improvement with each of these combinations is supra-additive (exhibited synergism) in a statistically significant, dose-dependent manner compared to the predicted additive improvements of each of the antibodies alone. Again, no distinctions in improvement are found based on gender.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM12+IgM42 significantly enhanced neurite outgrowth compared to vehicle controls (p<0.05). The degree of neurite outgrowth is supraadditive compared to the additive effect of each antibody administered alone. Thus, it is understood that these antibodies elicit outgrowth by distinct mechanisms of action; this is consistent with the respective distinct binding patterns of these antibodies to neural tissue.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM22+IgM 46 produced a significant increase in myelination compared to vehicle-treated controls (p<0.05). Further, the degree of remyelination is supraadditive compared to the predicted additive effect of IgM22 or IgM46 administered alone. Without being bound by theory, this is understood to be a result of paracrine activity. Accordingly, when growing neurons and growing oligodendrocytes are each present, the cells respectively elicit paracrine production that positively affect the other cell type under evaluation.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM12+IgM 22 produce a significant increase in myelination as well as neuron growth compared to vehicle-treated controls in the injured spinal cord (p<0.05). Further, the degree of neuron growth and remyelination is supraadditive compared to the effect of IgM12 or IgM22, respectively, administered alone at the doses used here. Without being bound by theory, this is understood to be a result of paracrine activity. Accordingly, when growing neurons and growing oligodendrocytes are each present, these cells respectively elicit paracrine production that positively affects the other cell type under evaluation.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM12+IgM 46 produce a significant increase in myelination as well as neuron growth compared to vehicle-treated controls (p<0.05). Further, the degree of neuron growth and remyelination is supraadditive compared to the effect of IgM12 or IgM46, respectively, administered alone at the doses used here. Without being bound by theory, this is understood to be a result of paracrine activity. Accordingly, when growing neurons and growing oligodendrocytes are each present, the cells respectively elicit paracrine production that positively affect the other cell type under evaluation.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM22+IgM 42 produce a significant increase in myelination as well as neuron growth compared to vehicle-treated controls (p<0.05). Further, the degree of neuron growth and remyelination is supraadditive compared to the effect of IgM22 or IgM42, respectively, administered alone at the doses used here. Without being bound by theory, this is understood to be a result of paracrine activity. Accordingly, when growing neurons and growing oligodendrocytes are each present, the cells respectively elicit paracrine production that positively affect the other cell type under evaluation.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM46+IgM 42 produce a significant increase in myelination as well as neuron growth compared to vehicle-treated controls (p<0.05). Further, the degree of neuron growth and remyelination is supraadditive compared to the effect of IgM46 or IgM42, respectively, administered alone at the doses used here. Without being bound by theory, this is understood to be a result of paracrine activity. Accordingly, when growing neurons and growing oligodendrocytes are each present, the cells respectively elicit paracrine production that positively affect the other cell type under evaluation.
IgM antibodies are evaluated for their ability to promote functional improvement and augment the processes of remyelination, neurite outgrowth or both in a spinal cord injury model in rats. The model involves laterally compressing the spinal cord between the blades of modified cover slip forceps, where the width of the blade of forceps is 2.5 mm, to a pre-set separation of the blades to 0.9 mm for a period of 15 seconds. The resulting lesion has characteristics similar to those found in human SCI (Gruner et al., 1995)
Male and female rats (approximately 200-225 g, Long Evans) undergo surgery to produce a spinal cord injury as described above. Recombinant IgM antibodies or vehicle treatment are given intravenously 10 min after surgery. Hind limb locomotor function and gait are evaluated for a period of 12 weeks using the BBB locomotor rating scale (see, e.g., Basso D M, Beattie M S, Bresnahan J C, Anderson D K, Faden A I, Gruner J A, Holford T R, Hsu C Y, Noble L J, Nockels R, Perot P L, Salzman S K, Young W. (1996) MASCIS evaluation of open field locomotor scores: Effects of experience and teamwork on reliability. Journal of Neurotrauma, 13:343-359; Basso D M, Beattie M S, Bresnahan J C. (1995) A sensitive and reliable locomotor rating scale for open field testing in rats. Journal of Neurotrauma, 12:1-21) Rats are tested at 1, 3, 5, 7 and 10 days, and then weekly following SCI for 9-12 weeks on the BBB Changes from baseline are quantitated.
At the completion of the experiment, animals are euthanized by overexposure to CO2. Brains and spinal cords are removed for evaluation of 1) degree of myelination (electron microscopic analysis of plastic-embedded paraformaldehyde/glutaraldehyde fixed osmicated tissue) and 2) neurite growth (assessment of the density of neurites by stereological assessment).
In this experiment, recombinant human antibodies are administered alone at three dose levels as indicated in Table 5A and Table 5B.
(*) X indicates improvement, X+ indicates more improvement, and X++ indicates even more improvement. The improvement score values are relative to the dosing of a given antibody. Thus an X+ is a greater improvement than X for that same Ab. The improvement X for one Ab is not necessarily the same as the X value for another Ab; the X+ value of one Ab is not necessarily the same as the X+ value of another Ab, and the X+++ value of one Ab is not necessarily the same as the X+++ value of another Ab.
In this example, the recombinant antibodies IgM12, IgM 42, IgM22 and IgM46 are each found to produce statistically significant, dose-dependent improvements in hind limb locomotor function with improved BBB parameters (p<0.05 for each endpoint compared to vehicle treatment). Animals treated with vehicle yield a stable BBB score within 6 weeks of a moderate level of spinal cord injury. A significant, dose-dependent change in BBB score over the dose range from 0.025-2.5 mg/kg, where X is an improvement, are found for each Ab, with an improvement X increase in BBB level at the low dose, a greater improvement X+ BBB increase with 0.25 mg/kg and an even greater BBB improvement X+++ at the 2.5 mg/kg dose. This trend is observed for group sizes of 12 animals powered at a level of 0.8 and an alpha level of 0.05. Thus, each of antibodies IgM12, IgM 42, IgM22 and IgM46 No distinctions in improvement are found based on gender. produce statistically significant, dose-dependent improvements in hind limb locomotor function with improved BBB (p<0.05 for each endpoint) compared to vehicle treatment.
IgM12 and IgM42 are found to produce statistically significant, dose-dependent increases in neurite outgrowth in brain and spinal cord sections from TMEV infected mice as assessed by stereology compared to vehicle-treated controls. Significant, dose-dependent changes in neurite outgrowth over the dose range from 0.025-2.5 mg/kg, where X is an improvement, are found for each Ab, with an improvement X increase in neurite outgrowth at the low dose, a greater improvement X+ increase in neurite outgrowth with 0.25 mg/kg and an even greater increase in neurite outgrowth X+++ at the 2.5 mg/kg dose. This trend is observed for group sizes of 12 animals powered at a level of 0.8 and an alpha level of 0.05.
IgM22 and IgM46 are found to produce statistically significant, dose-dependent increases in remyelination in brain and spinal cord sections from TMEV infected mice as assessed by stereology compared to vehicle-treated controls. Significant, dose-dependent changes in remyelination over the dose range from 0.025-2.5 mg/kg, where X is an improvement, are found for each Ab, with an improvement X increase in remyelination at the low dose, a greater improvement X+ increase in remyelination with 0.25 mg/kg and an even greater increase in remyelination X+++ at the 2.5 mg/kg dose. This trend is observed for group sizes of 12 animals powered at a level of 0.8 and an alpha level of 0.05.
In this Example, various combinations of fixed dose ratios of recombinant IgM antibodies are examined for improvement of neurological outcome in the spinal cord injury model as described in Example 14 herein. Accordingly, intravenous treatment with IgM antibody combinations (as admixtures) or vehicle control is given 10 min after injury. Locomotor endpoints are monitored as above. Further, myelination and neurite growth are evaluated to examine the changes produced by antibody combinations. The combinations evaluated are shown in Table 6A and Table 6B.
(*) X indicates improvement, X+ indicates more improvement, and X++ indicates even more improvement. The improvement score values are relative to the dosing of a given antibody. Thus an X+ is a greater improvement than X for that same Ab. The improvement X for one Ab is not necessarily the same as the X value for another Ab; the X+ value of one Ab is not necessarily the same as the X+ value of another Ab, and the X+++ value of one Ab is not necessarily the same as the X+++ value of another Ab.
In this experiment, each of recombinant antibody combinations IgM12+IgM42, IgM22+IgM46, IgM12+IgM22, IgM12+IgM46, IgM42+IgM22, and IgM42+IgM46 are found to produce statistically significant, dose-dependent improvements in hindlimb function (locomotor endpoints) as found by BBB parameters. No distinctions in improvement are found based on gender.
Furthermore, each of the combinations are found to improve locomotor function in a supra-additive (i.e. synergistic) manner compared to the improvements of each of the antibodies alone at the same dose. Again, no distinctions in improvement are found based on gender.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM12+IgM42 significantly enhanced neurite outgrowth compared to vehicle controls (p<0.05). The degree of neurite outgrowth is supraadditive compared to the additive effect of each antibody administered alone. Thus, it is understood that these antibodies elicit outgrowth by distinct mechanisms of action; this is consistent with the respective distinct binding patterns of these antibodies to neural tissue.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM22+IgM 46 produced a significant increase in myelination compared to vehicle-treated controls (p<0.05). Further, the degree of remyelination is supraadditive compared to the predicted additive effect of IgM22 or IgM46 administered alone. Without being bound by theory, this is understood to be a result of paracrine activity. Accordingly, when growing neurons and growing oligodendrocytes are each present, the cells respectively elicit paracrine production that positively affect the other cell type under evaluation.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM12+IgM 22 produce a significant increase in myelination as well as neuron growth compared to vehicle-treated controls in the injured spinal cord (p<0.05). Further, the degree of neuron growth and remyelination is supraadditive compared to the effect of IgM12 or IgM22, respectively, administered alone at the doses used here. Without being bound by theory, this is understood to be a result of paracrine activity. Accordingly, when growing neurons and growing oligodendrocytes are each present, these cells respectively elicit paracrine production that positively affects the other cell type under evaluation.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM12+IgM 46 produce a significant increase in myelination as well as neuron growth compared to vehicle-treated controls (p<0.05). Further, the degree of neuron growth and remyelination is supraadditive compared to the effect of IgM12 or IgM46, respectively, administered alone at the doses used here. Without being bound by theory, this is understood to be a result of paracrine activity. Accordingly, when growing neurons and growing oligodendrocytes are each present, the cells respectively elicit paracrine production that positively affect the other cell type under evaluation.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM22+IgM 42 produce a significant increase in myelination as well as neuron growth compared to vehicle-treated controls (p<0.05). Further, the degree of neuron growth and remyelination is supraadditive compared to the effect of IgM22 or IgM42, respectively, administered alone at the doses used here. Without being bound by theory, this is understood to be a result of paracrine activity. Accordingly, when growing neurons and growing oligodendrocytes are each present, the cells respectively elicit paracrine production that positively affect the other cell type under evaluation.
In addition to producing statistically significant, dose-dependent improvements in various sensorimotor endpoints including coat condition, gait parameters and Rotarod score compared to vehicle treatment (p<0.05 for each endpoint compared to vehicle treatment), the combination of IgM46+IgM 42 produce a significant increase in myelination as well as neuron growth compared to vehicle-treated controls (p<0.05). Further, the degree of neuron growth and remyelination is supraadditive compared to the effect of IgM46 or IgM42, respectively, administered alone at the doses used here. Without being bound by theory, this is understood to be a result of paracrine activity. Accordingly, when growing neurons and growing oligodendrocytes are each present, the cells respectively elicit paracrine production that positively affect the other cell type under evaluation.
We have demonstrated that a natural human serum antibody, sHIgM12, binds to neurons in vitro and promotes neurite outgrowth. We generated a recombinant form, rHIgM12, with identical properties. Intracerebral infection with Theiler's Murine Encephalomyelitis Virus (TMEV) of susceptible mouse strains causes chronic demyelinating disease with progressive axonal loss and neurologic dysfunction similar to progressive forms of multiple sclerosis. Treating this model with IgM class antibodies that bind to oligodendrocytes improves CNS remyelination (Warrington et al (2007) J Neurosci Res 85:967-976). In contrast, the serum-derived human monoclonal antibody (sHIgM12) that binds to neurons, promotes robust neurite outgrowth to the same degree as laminin, and reduces the inhibitory effects of CNS myelin on neurite outgrowth (Warrington et al (2004) J Neuropathol Exp Neurol 63(5):461-473). More recently a recombinant form of human sHIgM12 was generated (rHIgM12) with identical biological properties, as described above. To study the effects of rHIgM12 on the spinal cord axonal integrity we performed retrograde-labeling, a technique that relies on anatomically continuous and functionally preserved axons.
Methods
Retrograde Labeling:
After anesthetizing mice, dorsal laminectomy was performed at the lower thoracic vertebrae (T10-11). The spinal cord was hemi-sected on the right side and the hemisection site was packed with a sterile solution of 4% Fluorogold. One week after surgery, mice were sacrificed, and the brains removed. Serial sections (40 mm thick) of the brainstem were made and every fourth section was analyzed. Large, brightly fluorescent neurons were counted under 200× magnifications from 16 brainstem slices.
Results
The TMEV model offers a platform to develop strategies to promote neuroprotection and prevent axon loss. Early stages of disease include inflammation and demyelination; later stages present with axon loss and functional deficits. As detailed in the prior examples, rHIgM12 enters the spinal cord and localizes to neurofilament+ (NF) axons after a single 1 mg i.p. injection, as confirmed by confocal images (
Our laboratory demonstrated that a natural human serum antibody, sHIgM12, binds to neurons in vitro and promotes neurite outgrowth. We generated a recombinant form, rHIgM12, with identical properties. Intracerebral infection with Theiler's Murine Encephalomyelitis Virus (TMEV) of susceptible mouse strains results in chronic demyelinating disease with progressive axonal loss and neurologic dysfunction similar to progressive forms of multiple sclerosis. To study the effects of rHIgM12 on the motor function of TMEV-infected mice, we monitored spontaneous nocturnal activity over many weeks. Nocturnal behavior is a sensitive measure of rodent neurologic function because maximal activity changes are expected to occur during the normally active night time monitoring period. Mice were placed in activity boxes eight days prior to treatment to collect baseline spontaneous activity. After treatment, activity in each group was continuously recorded over 8 weeks. We chose a long 8-week monitoring period for two reasons: (1) we previously demonstrated that IgM induced remyelination is present by 5 weeks post treatment, and (2) TMEV-induced demyelinating disease in this strain progresses very slowly. Due to the long observation periods and large data sets, differences among treatment groups may be difficult to appreciate studying the original unfiltered recordings. To clearly delineate changes in the highly fluctuating original data we applied three different methods: (1) binning, (2) application of Gaussian low-pass filters (GF) and (3) polynomial fitting. Using each of the three methods we showed that compared to control IgM and saline, early treatment with rHIgM12 induced improvement in both horizontal and vertical motor function, whereas later treatment improved only horizontal activity. rHIgM12 did not alter activity of normal, uninfected mice. This study supports the hypothesis that treatment with a neuron-binding IgM not only protects neurons in vitro, but also influences functional motor improvement.
Introduction
Long-term monitoring and analysis of neurological function in rodent disease models remains a challenge. Nocturnal behavior is a sensitive measure of rodent neurologic function because maximal activity changes are expected to occur during the normally active night time monitoring period [1]. However, in animal models of slowly progressive diseases performance monitoring often extends over several weeks. We previously reported that oligodendrocyte-binding antibody (rHIgM22) enhanced remyelination by 5 weeks after the treatment
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[2]. Taken together that both the evolution of disease and repair is a slow process and to assure that any fluctuation in activity is taken into account, we monitored prolonged activity with the same sampling density used in short-term monitoring. This created large and highly fluctuating data sets (
Intracerebral infection with Theiler's Murine Encephalomyelitis Virus (TMEV) of susceptible mouse strains results in chronic demyelinating disease with progressive neurologic dysfunction similar to progressive forms of multiple sclerosis [3]. Treating this model with IgM class antibodies that bind to oligodendrocytes improves CNS remyelination [4]. In contrast, a serum-derived human monoclonal antibody (sHIgM12) that binds to neurons, promotes robust neurite outgrowth to the same degree as laminin, and reduces the inhibitory effects of CNS myelin on neurite outgrowth [5]. More recently a recombinant form of human sHIgM12 was generated (rHIgM12) with identical biological properties. We showed previously that rHIgM12 has a half-life of 3.6 hours, but still crosses the blood brain barrier and binds to nervous tissues (unpublished observation). To study the effects of rHIgM12 on the activity of TMEV-infected mice we monitored spontaneous activity over several weeks using AccuScan activity boxes (Accuscan Instruments, Inc., Columbus, Ohio). We chose a relatively long 8-week monitoring period for two reasons: (1) IgM induced remyelination is present by 5 weeks post treatment, and (2) TMEV-induced demyelinating disease in this strain progresses very slowly compared to the purely autoimmune EAE models of MS [6]. Due to the long observation periods compared to previously published studies (TABLE 7), identifying changes by visual inspection of raw data proved difficult.
Materials and Methods:
Mice:
SJL/J mice (Jackson Laboratories, Bar Harbor, Me.) were housed and bred in_Mayo Clinic's animal care facility. Animal protocols were approved by the Mayo Clinic— Institutional Animal Care and Use Committee.
Theiler's Virus Model of Demyelination:
Demyelinating disease was induced in 6- to 8-week-old female mice by_intracerebral injection of TMEV. A 27-gauge needle delivered 1001 containing 2.0×105_plague-forming units of Daniel's strain TMEV. This resulted in >98% incidence of infection with rare fatalities. All animals developed mild encephalitis, which resolved within 2 weeks. Animals worsen over the next 6-8 months with chronic spinal cord demyelinating disease. Axon injury and loss begin three months after infection correlating with neurologic dysfunction [3].
Antibody Treatment:
SJL mice (uninfected, 45 and 90 days post infection) were treated with a single 200 μg intraperitoneal dose of antibodies (rHIgM12 or isotype IgM control) dissolved in 0.5 ml of PBS. Third group was treated with 0.5 ml PBS only.
Spontaneous Activity Monitoring:
Spontaneous locomotor activity was recorded with Digiscan open field (OF) apparatus (Omnitech Electronics; Columbus, Ohio) and Versamax software, v.4.12-1AFE (Accuscan Instruments, Inc., Columbus, Ohio). The apparatus consists of six acrylic cages (40×40×30.5 cm) supported by a metal frame that holds two sets of photo cells. The device measures the number of discrete horizontal and vertical movements by tabulating the number of projected infrared beam interruptions. In all cages mice were exposed to identical environmental conditions: (a) freely accessible food and water, (b) a normal 12 h light/dark cycle, (c) 70° F. ambient temperature. In each experiment hyperactive and, in rare occasion, overweight animals were excluded and the remainder of mice were randomized. Several groups of 5 SJL mice were placed in the center of the each cage and the baseline spontaneous activity was collected over the period of 8 consecutive days. After this period, three groups of mice with the most similar baseline activity were treated with rHIgM12, control IgM antibody or saline and then monitored over the period of 8 weeks. Data was collected as number of beam breaks per 1-hour blocks. The total horizontal and vertical activities were recorded using Versadat program, v.3.02-1AFE (Accuscan Instruments). We could not put more than 5 animals per activity box because this is the maximal number of animals allowed by Institutional Animal Care and Use Committee (IACUC).
Data Analysis:
Differences among treatment groups may be difficult to appreciate studying original unfiltered recordings (
Data binning is the simplest method and replaces a group of data points within a preselected bin by their average value. In our case, we selected a nocturnal bin given that murine activity peaks at night. Therefore, we replaced all nocturnal readings (12 h/day) by their average value as shown in
Gaussian filtering (GF) (also known as low-pass filtering, data smoothing, or sensitivity enhancement) is a noise-reduction procedure commonly used in Fourier transform spectroscopy and image processing [7]. GF, performed with an appropriate selection of Gaussian broadening (GB, in days) filtered out high-frequency fluctuations at a desired level. The filter choice is arbitrary and may be guided by the rate of expected activity changes. GF is a smoothing method using information from points taken from both sides of a value and weighting the influence of these points such that influence fades according to the Gaussian function. Computationally, GF can be implemented in two equivalent ways: 1) Fourier transformation (FT) of the data, followed by multiplication with a Gaussian function and inverse FT of the product; and 2) direct convolution of the data with a Gaussian kernel. In high-level software packages (Matlab (Mathworks) or Mathematica (Wolfram)) the Gaussian filter function is available with minimal or no programming by the user. With appropriate selection of GB the above detailed GF method enables simplified visualization of highly complex and heterogeneous data. One limitation of GF is that whereas it allows for easy visualization of trends, statistical comparisons are complicated by the choice of the GB.
For comparison and to demonstrate a method that allows for simplified statistical comparison, we fit polynomials to the data. These models allowed for polynomial terms up through the any degree (xn), and estimated shape parameters separately for each treatment group (interaction terms). Our choice of a 6th degree polynomial was arbitrary after exploring several options, but allowed sufficient flexibility to model non-linear effects over time. Because the different treatment groups were optimally fit using varying order polynomials, we chose to allow for the higher order flexibility. Akaike Information Criteria (AIC) was used to determine the “best fit” of polynomial lines across several of the treatment groups [8]. AIC is a method of model comparison which balances the gain in R2 by adding additional terms, but penalizes for overcomplexity (i.e., use of degrees of freedom). In general, the 3rd order fit was sufficient to capture the trend of the data, and for some cases the 2nd order or even the linear fit was “best” according to AIC. However, our primary goal was to compare treatment groups at observed time points. Because of the large number of data points, and because we are not using the polynomial fit to predict (or extrapolate) treatment values outside of our observed data, the impact of “overfitting” on results is minimal.
One advantage of polynomial fitting is that the statistical comparison of treatment groups is straightforward: treatments can be compared at specified time points using the predicted model values and respective standard errors. Direct pairwise comparisons of treatments can be performed at regular intervals across the entire time frame to determine when treatment groups have significantly diverged. Finally, the polynomial fit removes additional medium and low frequency noise which focuses visual attention on the general trend over the entire time frame.
However, within each of the experiments some groups of mice had somewhat different baseline horizontal and vertical activity (8 days). Therefore, we first used Z-values to standardize baseline activity independently for each group and then performed Gaussian filtering or fitted polynomials to these values.
Statistical Analysis:
Binning data and Gaussian low-pass filter smoothing of data were performed by using a macro written in Mathematica (Wolfram). Macro and instructions are available on mayoresearch.mayo.edu/mayo/research/rodriguez_lab/software.cfm. Polynomial regression models and statistical comparisons of treatment groups were performed using the predicted model values and respective standard errors based on the z-statistic (SAS Institute, Inc.). Direct pairwise comparisons of treatments were performed for each day across the entire time frame, and statistical significance was determined at the typical α=0.05 threshold. No adjustments were made for multiple comparisons.
Results
rHIgM12 Improves Horizontal Activity in SJL Mice when Given at 90 Dpi
Three groups of 5 SJL mice at 90 days post infection (dpi) were placed in activity boxes and baseline activity was measured for 8 consecutive days. Two groups of mice were treated with a single 200 μg dose of rHIgM12 or an isotype-control IgM. The third group was treated with saline. After the treatment, spontaneous activity was continuously recorded over 8 weeks. Because data was collected in 1-hour blocks, we obtained approximately 900 data points for each group. This original, raw data (
rHIgM12 Improves Horizontal and Vertical Activity in SJL Mice when Given at 45 Dpi
The previous study used vertical activity (rearing behavior) as a primary readout [1]. Due to axonal dropout in chronically TMEV-infected mice, hind limbs became progressively weak and stiff so rearing was reduced. In the first experiment of this study, when rHIgM12 was administered at the time of maximal demyelination (90 dpi) and onset of progressive axonal loss, only horizontal activity was improved. The rearing behavior was not affected and was equivalent in all three treatment groups. Therefore we asked whether treatment at an earlier time point may be more beneficial. In a second experiment, groups of 5 mice were treated at 45 dpi with a single 200 μg dose of rHIgM12, an isotype-control IgM or saline. An identical experimental design was used; baseline activity was collected for 8 days, and post-treatment activity for 8 weeks. In this experiment, beginning around 2 weeks post-treatment, rHIgM12-treated mice showed clear improvements in both horizontal and vertical activity. This was evident after using all three methods: averaging data, applying Gaussian filter or polynomial fitting (
rHIgM12 does not Alter the Spontaneous Activity in Normal Uninfected Mice
Treatment with rHIgM12 in previous two experiments showed clear beneficial effect in neurologically disabled infected mice. To exclude the possibility that this antibody may have irritable properties and therefore elicits increased motor function, we performed similar experiment with uninfected mice. Three groups of age matched uninfected mice were treated with rHIgM12, control IgM or saline. Compared to the activity enhancement in infected mice, rHIgM12 as well as the other two treatments did not induce any increase in motor function of normal mice (
Discussion
There is a critical need for the development of neuroprotective therapies for multiple sclerosis as well as for other demyelinating and neurodegenerative diseases. Even though there are some anti-inflammatory drugs that may indirectly lead to a decrease in axonal damage during inflammatory CNS disease, there are no drugs that act directly at the level of neurons/axons. The main goal of neuroprotection is to limit neuronal dysfunction and to attempt to maintain the functional integrity of neurons and axons. For many years demyelination, the pathological hallmark of MS, was considered as a cause of permanent neurological deficits. It is clear now that demyelination is necessary, but not sufficient for permanent axonal loss [9]. Demyelination only predisposes denuded axons to the secondary injury caused by either T-cell cytotoxicity or loss of local neurotrophic support from dead oligodendrocytes [10].
Previous observation that neuron-binding antibody sHIgM12 promoted robust neurite extension [5] represents a clear beneficial in vitro response. Because recombinant version of this antibody showed similar in vitro properties we asked whether it would affect motor activity of mice with TMEV-induced demyelinating disease. Analysis of motor function was performed by monitoring the spontaneous nocturnal activity. First, we treated mice at the time of maximal demyelination and onset of axonal loss (90 dpi). Eight weeks after the treatment, rHIgM12 improved only horizontal motor activity, whereas vertical activity was not affected. However, when mice were treated earlier in the disease (at 45 dpi), rHIgM12 improved both horizontal and vertical activity. In the chronic TMEV-induced disease, rearing behavior (vertical activity) is most severely affected and it appears that degeneration and loss of axons responsible for this activity is irreversible. Conversely, the early phase of the disease, when these axons are not irreversibly injured, appears to be ideal time for the treatment. Jones et al. utilized EAE model and by studying axonal dropout and motor function they proposed an identical paradigm; treatment with neuroprotective drugs should begin early in the disease, even before the onset of motor deficits [11]. Second, because the functional improvement occurs about two weeks after the treatment and starts to fade approximately 25-30 days later, it may be that repeated treatments will be necessary to sustain motor function. Unfortunately in our studies, it was not possible to test multiple doses of human IgMs because of anti-human antibody immune response in mice which results in anaphylaxis. A2B5 is a mouse monoclonal antibody that also promotes neurite outgrowth [5] and represents a likely candidate to test single versus multiple dosing on functional outcome and its duration of action. Finally, none of the treatments had an effect on motor function of uninfected, normal animals. Irrespective of the treatment all groups of normal mice showed a gradual decline in spontaneous activity, which may be explained by habituation to the environment. This decline of activity in normal animals makes rHIgM12-induced increase in activity of diseased mice even more impressive.
We have demonstrated improvement in motor function in a chronic progressive model of inflammatory demyelinating disease in which has been generally very difficult to prevent the development of neurologic deficits. Therefore, neuron-binding monoclonal antibody rHIgM12 represents very promising therapeutic agent for the treatment not only of human MS, but also other demyelinating or neurodegenerative disorders. In addition, because there are examples of clinically silent MS attacks [12, 13], we and others have proposed that neuroprotective compounds should be complemented with immunomodulatory agents [11]. We propose that the combined treatment of immunomodulatory drugs and rHIgM12 may result in a significant enhancement of CNS preservation and repair following axonal injury.
Taken together, results from this study provide three important conclusions: 1) the stage of the disease when the treatment is given is critical (early treatment is more beneficial); 2) to further maintain improved motor function, there may be a need for repeated treatments and 3) rHIgM12 is not toxic and does not affect motor function in normal, uninfected animals. The findings are consistent with the hypothesis that a recombinant antibody that targets neurons improve neurologic function in a chronic axonal model of demyelination.
Amyotrophic lateral sclerosis (ALS) is a devastating neurological illness that primarily affects anterior horn cells and corticospinal tract neurons. ALS is a motor neuron disease characterized by progressive degeneration of the motor cells in the brain and spinal cord. The motor cells (neurons) control the muscles that enable an individual to move around, speak, breathe and swallow. With no nerves to activate them, muscles gradually weaken and waste. Despite extensive research, the etiology of this disorder is largely unknown, and there are no effective treatments. Genes implicated in a minority of patients with a rare genetic form of ALS provide a potential clue to this disorder.[1] One identified gene mutation has been the Cu/Zn SOD (copper/zinc superoxide dismutase) mutation, which is present in a small percentage of patients with the genetic form of ALS.[2] It is apparent that patients carrying the SOD mutations have very similar neurological outcomes compared to patients who develop the disease spontaneously without an associated genetic mutation.[3] This enzyme catalyzes superoxide to oxygen and hydrogen peroxide. SOD1 is the form of the enzyme associated with ALS. There appears to be a gain of function of SOD1, which affects fast axonal transport.[4] The frequency of the SOD mutation in familial ALS varies from 12 to 23% and the gene is usually inherited as an autosomal dominant.
Identifying the gene allowed the development of animal models with disease features of ALS for designing and testing new drugs. Because inherited and non-inherited forms of ALS are similar diseases, the underlying cause may be related. Therefore, drugs that are effective in the mouse models of inherited ALS may also work in people with the more common random forms of ALS. The availability of transgenic mouse models with human SOD1 genes and the pathologic features of ALS have advanced the development of drugs for the disease.[5] These transgenic mice develop progressive motor neuron loss and neurologic deficits. Because inherited and noninherited forms of ALS are similar clinically, the underlying defects in motor neuron function may be related. Reagents efficacious in SOD1-linked ALS may also aid the more prevalent sporadic forms of ALS. At present there is only one drug on the market for ALS, the glutamate blocking drug Rilutek® (Riluzole tablets). However, studies have shown that this drug does not improve patient quality of life and may only extend life an average of 2 months. Clearly more effective drugs are critically needed.
The laboratory has developed novel therapies for the treatment of demyelinating and degenerative disorders of the central nervous system (CNS)[6] and have identified a series of human monoclonal antibodies (mAbs) that bind either to oligodendrocytes[7] or neurons,[8] which have been shown to induce repair in the CNS. These antibodies have been cloned, sequenced[9] and produced in large quantities in a GMP facility for future clinical trials.[10] Recombinant human antibody IgM12 (rHIgM12) is derived from an antibody isolated from a patient with Waldenstrom's macroglobulinemia.[11] This antibody specifically labels neurons and axons of the CNS.[8] Despite being an IgM antibody, IgM12, as shown in the above Examples, crosses the blood-brain barrier and binds specifically to axons and neurons within the CNS. In vitro rHIgM12 binds to a wide array of neurons, including cerebellar granular neurons, cortical neurons, hippocampal neurons and retinal ganglion cell neurons.[12] Experiments in vitro demonstrate that rHIgM12 protects neurons from cell death. Monoclonal antibody rHIgM12, administered to patients in early stages of ALS (both the genetic and spontaneous forms of disease), may act to protect anterior horn cells and prevent axon injury and thereby delay the onset of disability and improve survival.
Results
We have performed experiments treating mice with the G86R hSOD1 mutation[13] (FVBTg SOD1 G86R M1Jwg, Jackson Labs) with human antibody rHIgM12. G86R mice appear normal at birth. However, beginning at approximately 90-100 days of age, they undergo pronounced weight loss, develop significant muscle atrophy, and die of respiratory failure within weeks of the precipitous weight loss. LUDOLPH? In a randomized, “blinded” trial, these mice received GMP-purified rHIgM12 at the age of 55 days as a single intraperitoneal dose (200 μg). In contrast, the placebo group received phosphate buffered saline (PBS). A few mice were left untreated to determine the natural course of the disease without human handling. Because the data for PBS-treated and non-treated mice were similar, the groups were combined for statistical analyses. Mice were randomized for treatment by one investigator in our laboratory and were observed for neurological deficits by another “blinded” investigator until they became moribund. The treating investigators and other investigators performing the pathologic analyses were unaware of the randomization protocol until the code was broken.
Animals were weighed on a weekly basis to determine whether treatment with the human mAbs would not only increase survival but also delay the onset of weight loss. The results were striking and showed a statistically significant increase in survival in animals receiving rHIgM12 in comparison to animals receiving PBS. On average, investigators recorded an increased survival of 25 to 30 days, which, by Kaplan-Meier curves (
When animals reached the moribund phase, they were sacrificed and perfused with Trump's fixative. The spinal cords were removed and cut into 1 mm blocks and embedded in Araldite plastic for 1 μm thick sections. These sections were examined histologically. Animals that developed ALS from the SOD mutation showed significant axonal degeneration in the white-matter tracts, such that when the axon collapses, relatively easily identified myelin whorls develop in the spinal cord white matter. When the number of spinal cord whorls (degenerating axons) was quantified in thoracic sections in animals receiving rHIgM12 versus PBS, there was a statistically significant decrease in the number of myelin whorls in animals treated with monoclonal antibody therapy (
Spinal cord sections were also stained with an antibody for NeuN, a marker that specifically labels neurons in the CNS and very nicely defines the anterior horn cells as well as neurons in the posterior horn. A number of anterior horn cells were quantitated at the thoracic spinal cord level in animals receiving rHIgM12 compared to PBS (
The human antibody, rHIgM12, binds to the surface of many types of CNS neurons obtained from many species including mice, humans (
Human antibodies were also tested as substrates on tissue culture plates, and compared for the ability to promote normal cell process extension from cerebellar or cortical neurons. rHIgM12 and sHIgM42, antibodies that bind to the surface of neurons, and rHIgM22 and sHIgM39, antibodies that do not bind to neurons, were compared to the potent process supporting extracellular matrix molecule, laminin. Growing neurons on a substrate of human antibodies rHIgM12 or sHIgM42 resulted in a dramatic extension of neuron outgrowth, similar to that observed with laminin [8]. This study also showed that neurons behave normally in the presence of rHIgM12.
It has been generally accepted dogma that IgMs with a molecular weight of close to 1 million are too large to cross the blood brain barrier (BBB) from the circulation to enter the CNS [15] [16]. However, there is accumulating evidence some antibodies do cross the BBB. We have above described detecting rHIgM12 within the spinal cord after peripheral injection. 1.0 mg of rHIgM12 or a control human IgM were administered intraperitoneally to mice with demyelinated spinal cord lesions. Four hours later mice were killed and sections of the spinal cord were immunostained for the presence of human IgM mu chain and anti-neurofilament. In mice receiving rHIgM12 confocal microscopy demonstrated human mu chain within demyelinated lesions co-localized with antineurofilament, a marker of axons, in parallel tracts and as bundles cut on end (see
While the studies provided are in animal models, there are a number of tantalizing aspects of these research results that further indicate that this novel approach will be effective in human patients. Importantly, the IgM12 antibody described and used herein is a fully human, monoclonal antibody. As a result, only a single dose of this antibody can be used in mice. Subsequent doses cause animals to develop an immune response to the antibody resulting in either neutralization of rHIgM12 or the death of the animal due to anaphylaxis. However, since these are “true” human antibodies, human patients treated with rHIgM12 are unlikely to develop an immune response to them. Also, rHIgM12 can potentially be given on a continuing intermittent basis to patients without deleterious effect or development of an antibody-blocking reaction. Because rHIgM12 is a natural human autoantibody, adverse side effects are unlikely, and therefore, we expect the toxicity of this agent to be minimal. There is much evidence that rHIgM12 will be safe in humans. Before these positive results in the ALS model the serum form of the antibody, sHIgM12, was tested in several models of neurologic disease without toxicity, as described above herein. In these studies we found, 1) no increase in CNS pathology in mice with virus mediated demyelination after a 1 mg dose, 2) no increase in severity of clinical scores in mice with active EAE after a 200 μg dose and 3) clean blood chemistry and tissue pathology in normal CD-1 mice after a 300 μg dose. Even so, it is notable that a single dose to a mouse in a recognized animal model of ALS gave remarkable results.
rHIgM12 has already been grown in a GMP facility according to FDA guidelines, and, per FDA guidelines, stable, transfected cell lines have been generated and stored without any adventitial infections. These cell lines have been tested against a panel of >50 infectious organisms, all with negative results. In addition, the cell lines make large amounts of antibody in tissue culture (150 μg/ml). A methodology for purifying rHIgM12 to >97% purity without adventitial viruses, DNA, RNA or other extraneous material according to FDA guidelines has been established, providing a strong preclinical basis for rHIgM12 in future initial phase clinical trial in patients with early stages of ALS.
Ongoing Studies
Having shown above that the recombinant human monoclonal antibody (rHIgM12) can prolong survival in a transgenic model of human ALS by preventing the loss of anterior horn cells and axons, studies are ongoing to generate pre-clinical data through pharmacokinetics and toxicology to move toward a phase I clinical trial in ALS patients.
Blinded Studies Versus Placebo Ab:
A definitive “blinded,” placebo-controlled study is performed in two strains of SOD mice with the ALS phenotype (SOD1 G86R and G93A), testing recombinant human antibody rHIgM12 versus an isotype control human antibody, sHIgM39. The efficacy of a single 200 μg dose of recombinant human antibody, rHIgM12, is tested to reduce disease in both the G86R and G93A SOD1 [14] (B6 Cg-Tg SOD1 G93A 1Gur, Jackson Labs) mutant transgenic mouse models, compared to a 200 μg dose of an isotype control human antibody, sHIgM39. Antibody treatment is at 55 days of age following ENMC recommendation of pre-onset treatment [18], with results to mirror the pilot studies comparing rHIgM12 to PBS (
Dose Titration Study:
Following the positive results in the above study, a dose-titration study (a single dose of 0, 5, 50, 100 and 250 μg per mouse given at 55 days of age) is undertaken to determine the minimal dose required to protect SOD1 mice from death. MR spectroscopy of the mouse brainstem is used to measure N-acetyl aspartate (NAA). We have shown in other models of neurologic disease that NM in the brainstem is an excellent surrogate indicator of axon health throughout the spinal cord.[17] The MR spectroscopy data helps validate NM as a surrogate marker of antibody efficacy in potential human trials using rHIgM12. A single dose of 0, 5, 50, 100 and 250 μg is given intraperitoneally at 55 days of age to groups of 20-24 SOD1 mice. Primary and secondary endpoints and adverse events are the same as described above with the addition of MR spectroscopy at the brainstem to measure Nacetyl aspartate (NAA). MR spectroscopy is collected for each mouse on the day of antibody treatment, at 100 days of age and immediately prior to sacrifice. A 10% (P<0.05) increase in brain stem NAA concentration in any rHIgM12 treated group at the 100 day or final scan compared saline treated mice is considered an improvement.
Pharmacokinetic Studies and BBB:
Studies are performed in SOD1 G86R and G93A mice at 50-70 days of age [18] after a single 200 μg intravenous dose, using an established ELISA detection system that specifically detects human IgM within the background of normal mouse blood immunoglobulin. Human IgM is measured in the blood at various time points after dosing (0, 15 min, 30 min, 1 hr, 4 hr, 8 hr, 12 hr, 18 hr, 24 hr, 2 days, 3 days, 5 days, and 7 days). Because the blood volume of mice is small (total <1.5 ml), three individual mice are used for each collection point.
rHIgM12 is proposed to act directly on the nervous system, crossing the blood-brain barrier after peripheral injection to interact with neurons to protect them from death. It is possible, but unlikely, that the human antibody does not cross the blood-brain barrier, but stimulates aspects of an immune response, which then provides axon protection. In vivo tracking of 35S labeled rHIgM12 is used to fully address this question. Two dose levels of 35S labeled rHIgM12, 250 μg and the minimal effective dose established above, are followed in SOD1 mice at 50-70 days of age. After an intravenous dose of 35S labeled rHIgM12, the percentage of 35S that crosses the blood-brain barrier and is found in brain/spinal cord parenchyma at 4, 8, 24, 48 and 72 hr post injection is determined. In addition, the site of 35S localization in the brain/spinal cord is determined using autoradiography techniques already published. [19]
Serum Half Life Studies:
Blood kinetics for rHIgM12 is performed using a dose of 200 μg in the SOD1 strain(s) in which rHIgM12 demonstrated efficacy. The study is performed in groups of 3 SOD1 mice per time point; 13 collection points over 7 days after intravenous injection. SOD1 mice are treated at 50-70 days of age to understand antibody kinetics at the time of treatment. rHIgM12 serum half life, saturation of exposure and the presence of neutralizing Abs IgM will be determined. Studies tracking isotopically (35S) labeled rHIgM12 require the determination of the minimal effective dose described above. SOD1 mice are given a single intravenous dose of 250 μg and the minimum effective dose of rHIgM12 (containing at least 1×107 cpm) [19] at 50-70 days of age to address whether rHIgM12 enters the CNS at the time of therapeutic treatment. At 4, 8, 24, 48 and 72 hr post injection major tissues are acutely removed, including brain, spinal cord, liver, heart, lung, stomach, intestine, muscle, spleen, liver, pancreas. A 150 mg portion of tissue is removed, weighed, solubilized in Solvable (Perkin Elmer) and cpm determined in scintillation fluid (Ultima Gold, Perkin Elmer). Isotopically labeled rHIgM12 is localized in spinal cord sections using autoradiography [19]. In this experiment, the primary endpoint is an accumulation of 35S isotope in the brain or spinal cord of mice at 4, 8, 24, 48 and 72 hr after rHIgM12 injection compared to the zero time point controls. A 50% (P<0.05) increase in 35S counts/mg in whole brain or spinal cord any time point is considered significant and evidence that rHIgM12 can enter the CNS. For autoradiography studies mice are dosed with labeled rHIgM12 and spinal cords removed at a time in which rHIgM12 was increased in the CNS. A 50% increase in silver grains/mm2 over neurons in spinal cord sections is considered significant evidence of antibody targeting in vivo.
Initial Toxicity Studies:
Experiments are conducted with rHIgM12 to determine whether the antibody is toxic in normal CD-1 mice and rabbits. Groups of 10 normal CD-1 mice of both genders are administered 1 time (1×), 10 times (10×) and 20 times (20×) the minimal efficacious dose of rHIgM12 determined above or saline intravenously once or daily for 7 days. Two weeks later blood and tissues are collected by a “total” necropsy and analyzed. Tissues sections of all major organs are examined “blinded” by a veterinary pathologist with expertise in toxicology assessments. Blood is characterized in chemistry and hematology for the usual panel of toxicology screens including blood studies for liver enzymes, heart enzymes, electrolytes and effects on hematology group. Identical exposure studies are performed in a non-rodent species; two rabbits of each sex are tested at each dose. In addition, tissue cross reactivity studies using rHIgM12 are used to determine whether the antibody binds to any other tissues or organs. A panel of paraffin embedded tissue sections from mouse, rabbit, primate and human (Zymed) is immunolabeled with rHIgM12 or a control human IgM. The intensity and structures bound within each tissue are imaged and compared to rHIgM12 and control IgM labeling of live tissue slices cut with a tissue chopper[7] since this more closely mimics the situation in vivo. In addition, the binding of rHIgM12 and a control antibody is tested on frozen human and primate tissue as consistent with the preliminary toxicology section of an Investigational New Drug application to the FDA. Tissue cross-reactivity studies provide clues as to which organs should be particularly monitored during the exposure studies in mice and rabbits.
Tissue Binding:
Following efficacy determination, these studies address binding to target and off target tissues. Commercially available tissue arrays (Zymed) and sections of human and cynomolgus monkey (Charles River) are immunolabeled with 10 μg/ml of rHIgM12 and control human IgM, sHIgM39. Label intensity is compared using digital images. rHIgM12 binding to fixed paraffin-embedded tissue arrays and frozen human and primate brain and spinal cord is compared to antibody binding observed on live mouse cerebellar slices. Antibody binding to live cerebellar slices a standard potency assay we have utilized and the first screen in which the serum form of rHIgM12 was identified.
The incidence of ischemic stroke increases with age. The aging of our population results in an increasing number of strokes per annum, placing a cumulative burden on our health care infrastructure and families. Stroke is the leading cause of long-term disability in the United States. Each year, close to 800,000 people suffer a stroke. Following ischemic injury, the disability associated with clinical deficits is primarily due to dysfunction of neurons. The lack of functional recovery is in part attributed to the restriction of regeneration and neuroplasticity (1). There are currently no effective treatments to prevent or reverse stroke-related neurologic deficits.
Naturally occurring human monoclonal IgM class antibodies have been identified and utilized to promote CNS protection and repair, including myelin repair and axonal/neuronal recovery (2). We identified a serum-derived human monoclonal IgM that binds to the surface of neurons. The IgM binds to neurons across species, including human, and promotes neurite extension. This IgM protects neurons from apoptosis in vitro and preserves spinal cord axons in vivo as measured by magnetic resonance spectroscopy and histology of the spinal cord. A recombinant form, rHIgM12 has been synthesized that preserves the characteristics of the serum-derived form. The neuroprotective properties of rHIgM12 are similar to those observed with ganglioside GM1. Gangliosides may be a/the antigen of antibody IgM12 and rHIgM12. rHIgM12 co-localizes on the neuronal membrane with GM1, cholesterol and integrin β1. GM1 is enriched in membrane microdomains, which function to cluster cell receptors and signaling molecules. rHIgM12 appears to mimic the pleiotropic effects of GM1 by clustering neuron membrane domains.
The present studies were undertaken to assess the efficacy of rHIgM12 to reverse neurological deficits following cerebral ischemic injury. These studies are aimed at applications of the antibody in patients with early stages of cerebral ischemic injury or suffering from stroke. The central hypothesis is that the antibody IGM12 and rHIgM12-mediated neuroprotective effects are applicable in therapy to enhance cellular and tissue restoration and to promote overall recovery from ischemic stroke.
Therapeutic management of cerebral ischemia relies on prevention and reduction of risk factors, such as elevated blood pressure, thrombosis and carotid artery atherosclerosis. Interventional therapy of cerebral ischemia remains limited to enzymatic thrombolysis by use of recombinant tissue plasminogen activator rtPA (3-5), and to interventional removal of the blood clot via direct catheterization (6). However, rtPA has a short 3 hr therapeutic window and increased incidence of hemorrhagic cerebral ischemia if infused beyond the 3 hr time frame (7, 8). Protecting damaged neurons following cerebral ischemia is a promising strategy to limit permanent disability. While therapies that modulate the inflammatory response can have neuro-protective properties, there are currently very few drugs that act directly on neurons to protect them. Neuro-protection may be achieved by modulating neurotoxic inflammatory environment in the ischemic region. Previous studies using antibodies to treat cerebral ischemia have not yielded a potential benefit: antagonists to intercellular adhesion molecules were employed in a large multi-center trial, treated subjects had higher mortality rates and poorer outcomes when compared to placebo group (9). The use of anti-platelet antibodies in a phase III clinical trial in cerebral ischemia led to fatal hemorrhage in a small cohort of patients (10). The use of polyclonal human IgG (IVIg) resulted in improvement of an animal model of cerebral ischemia (11), however clinical trials reported thromboembolic complications following IVIg administration, leading to a mixed opinion on the use of IVIg to treat cerebral ischemia (12, 13). A goal has been to identify therapeutic reagents that directly target the nervous system. The recombinant form of a completely human antibody rHIgM12 promotes neuronal survival and may have applicable use as a restorative/neuroprotective therapeutic. The experiments in this example focus on the therapeutic effects of antibody IgM12, rHIgM12, in a mouse model of cerebral ischemia. The model utilized is a non-invasive photo-thrombotic model using photo-sensitive dye and hence more physiological than invasive models.
Our approach to protect neurons and improve behavior in animals following cerebral ischemia using a fully human monoclonal antibody is both original and innovative and the antibody has the potential as the first drug designed to target and protect neurons in cerebral ischemia and stroke. Relevant aspects of the molecule are listed below:
1) rHIgM12 binds to surface of neurons (see
2) rHIgM12 is a natural human autoantibody and adverse effects are unlikely.
3) rHIgM12, despite being an IgM crosses the blood-brain barrier (BBB) in normal SJL mice and in animals with inflammation (see
4) The present studies now demonstrate that when rHIgM12 is administered to animals following induction of ischemic stroke, it results in a clear improvement of function of the animals (
Results and Discussion
A unique approach was utilized to develop novel therapies for the treatment of injury to the central nervous system (CNS) (14, 15). A series of human monoclonal antibodies have been identified that bind either to oligodendrocytes (16) or neurons (17) and which have application in the CNS. Recombinant human antibody IgM12 (rHIgM12) is derived from an antibody isolated from a patient with Waldenstrom's macroglobulinemia. This antibody specifically labels neurons and axons of the CNS (17). Despite being an IgM antibody, it crosses the blood-brain barrier (BBB) (see
Standardization of a Mouse Model for Cerebral Ischemia
Photosensitive dye (Rose Bengal, RB) was utilized in a dye-mediated photo-thrombotic model of ischemic stroke (photo-thrombotic cerebral ischemia) in our laboratory. In 1985, Watson et al. introduced brain PT as a simple model of focal cerebral ischemia (Watson B D, et al (1985) Ann Neurol 17: 497-504). To achieve thrombosis, a photosensitive dye is injected systemically. Subsequent illumination through the intact skull leads to local activation of the dye with free radical formation and photoperoxidation of the endothelium. Clot formation is thereby mediated in illuminated vessels and occlusion of the vessels mimicks cerebral ischemia (Dietrich W D, et al (1987) Acta Neuropathol 72: 315-325). The PT lesions elicit a strong, but delayed inflammatory reaction (Schroeter M, et al (1997) Stroke 28: 382-386). This model has the advantage that the region of ischemia can be predefined and highly circumscribed, opening the possibility to coagulate distinct cortical areas with stereotactical precision.
RB, dissolved in PBS at 10 mg/mL was injected through the tail vein (0.02 mg/g body weight). The aperture (5 mm) of the articulating fiber-optic attached to a light source (150 W halogen lamp) was placed at a standard location on the mouse head. A minute after the injection of RB, brains were exposed to constant light (to activate RB) through the intact skull for 30 seconds. Upon activation, RB generates free radicals that disturb the endothelial cells within the microvasculature, which results in platelet aggregation and triggers coagulation that leads to occlusion of small blood vessels and causes thrombotic cerebral ischemia. We performed all experiments in 6 week old female CD-1® mice.
In a randomized, “blinded” trial, mice received GMP-purified rHIgM12 thirty minutes following induction of cerebral ischemia (an attempt to mimic the human clinical condition), as a single intraperitoneal dose (i.p. 200 μg in 500 μl). In contrast, the placebo group received phosphate-buffered saline (PBS). We standardized techniques to visualize and quantify ischemic region following cerebral ischemia (
rHIgM12 Improves Functional Activity in Animals Following Cerebral Ischemia without Significant Differences in Diffusion-Weighted Imaging (DWI)-Defined Infarct Volume
Functional deficits were computed using an Accuscan open-field apparatus. The apparatus consists of individual acrylic cages with photocells that measure discrete horizontal and vertical movements. Groups of 5 CD-1 mice were placed in each cage and baseline values were recorded for 1 week prior to the induction of cerebral ischemia. Data was collected as number of beam breaks per 1-hour blocks and expressed as % of horizontal (
DWI-MRI was utilized to define ischemic volume and to correlate functional improvement to reduction in infarct size. Mice were scanned on days 1, 3, 7 and 21 in a Bruker Avance 300 MHz (7 Tesla) small animal MRI system and obtained images in three-dimension (
rHIgM12 Treatment Improves MT-MRI Metrics and Demonstrates Significant Differences in MT Ratios
DWI imaging estimates the presence and extent of cytotoxic edema on water diffusion following ischemic stroke. In order to assess MRI measures more sensitive to tissue integrity and recovery after injury, we utilized magnetization transfer MRI (MT-MRI) in a subsequent experiment, in 10 mice on day 3 after stroke induction and following treatment with rHIgM12 or PBS sham treatment. The obtained images were imported into FSL (23, 24) and a 3D parametric MTR map was calculated in FSL MATHS. We used the standard formula of 100*((Mo−Mt)/Mo), where Mo is the 3D image without, and Mt is the 3D image with the MT pulse. Images were appropriately scaled to provide a gray scale percentile mapping output with values ranging from 0 to 100 (
rHIgM12 Binds to Mouse and Human Neurons and Protects Mouse Cortical Neurons from Oxidative Damage-Induced Death
It is hypothesized that rHIgM12 protects neurons in the ischemic region by binding to neurons. The human antibody, rHIgM12, binds to the surface of many types of CNS neurons obtained from mice and humans (see
In a different neurotoxic assay, cultured cortical neurons were directly subjected to hypoxic conditions (2.7% O2, 92.3% N2, 5% CO2 atmosphere for 4, 21 and 44 hrs (44 hrs, non-hypoxia chamber cells were considered as 0 hr control). The levels of caspase-3 were determined by Western blot (
A mouse model of cerebral ischemic stroke was used in the present studies to demonstrate the capacity of rIgM12 to reverse neurological deficits following and provide protection from cerebral ischemic injury. This model is additionally be applied to optimize dose formulation, to determine the percentage of antibody that crosses blood-brain-barrier, and to better understand protection of cultured neurons by rHIgM12 in vitro from ischemia-like conditions.
Dose and Biomarkers for Neurological Improvement
A placebo controlled randomized trial in mice using rHIgM12 is used to determine the minimum dose required for improvement of spontaneous activity and identify metabolic biomarkers for neurologic improvement. The above data indicates that 200 μg of rHIgM12 improved neurologic function in a mouse model of ischemic stroke. Determining the minimum effective dose is relevant to the design of safety studies. A dose-titration study of rHIgM12 is performed in mice following cerebral ischemia.
Cerebral ischemia in female CD-1 mice using the photo-thrombotic model with dye RB is used in dosing studies. Groups of 5 mice are treated i.p. with 5, 50, 100 or 500 μg of rHIgM12, or with a commercial control human IgM (Jackson ImmunoResearch cat 009-000-012) that does not bind to neurons, or with saline, within 30 minutes following the induction of cerebral ischemia. Neurologic function is measured before induction of cerebral ischemia or treatment and weekly in activity boxes. Groups of 5 mice are housed in activity boxes and spontaneous vertical and horizontal activity is recorded. Nocturnal horizontal activity is a sensitive measure of an animal's functional ability (25). In addition, all mice undergo DWI-MRI (
The primary endpoint is motor improvement assessed by monitoring spontaneous activity. A 20% increase in mean nocturnal activity (2000 beam breaks/hr) recorded over 72 hr compared to control groups over 5 days of a rHIgM12 treated group (P<0.05) is considered a biological significant improvement (25). Established methodology from our laboratory (25) is used to calculate statistical differences between groups. DWI-MRI analysis is performed in a blinded fashion using 3D ROI analysis tools in Analyze 11.0, a biomedical image analysis software package developed at Mayo Clinic (26, 27).
It is determined whether improvement of neurological function following treatment with rHIgM12 correlates with preserved NM metabolite (a metabolite associated with neuronal function (28)), and with relative normalization of the magnetization transfer ratio on MT-MRI in the brain. MT is an overall marker of tissue integrity and has been utilized as a sensitive marker for penumbra integrity in human ischemic stroke (29). These assays are useful as a future end-point of clinical trials in humans of rHIgM12 in cerebral ischemia.
Based on power calculations obtained for MT-MRI data, 12 mice per group are used in this experiment. Techniques were previously standardized to measure N-acetyl-asparate (NM) levels in the CNS (30). In order to investigate whether NAA can be used as metabolite imaging biomarker for rHIgM12-mediated functional improvement following cerebral ischemia, we have standardized a voxel to perform MRS in the ischemic region. NM metabolite is measured in animals treated with minimum effective dose, or isotype control IgM or saline. MRS is performed using the 7T vertical bore NMR spectrometer and MRS data obtained from a 3×2×1.5 mm voxel placed inside the ischemic area as identified on DWI and T2 weighted MRI. The contralateral hemisphere serves as an appropriate control for each mouse. As additional controls, mice in other groups are treated with control IgM or PBS. MT-MRI data is obtained by acquiring a standard PD-weighted RARE sequence with 256×96×96 matrix size, 6.4×1.92×1.92 cm FOV, TR:1500, TE:30, RARE factor of 16, with and without a MT pulse of a total MT time of 270 ms with excitation pulse bandwidth of 500 Hz and offset of 1500 Hz, before and after ischemic stroke followed by treatment with PBS or rHIgM12. Each experiment is repeated three times to confirm the reproducibility of using imaging biomarkers as endpoints of functional improvement, for a total of 108 mice (12 mice per group for a total of three groups, repeated three times) in this experiment.
Spectra for MRS are quantified using Bruker Biospin's TopSpin software and via LCModel (31-34). Statistical differences between groups is calculated by ANOVA (30). MTR data are computed using FSL MATHS and Analyze 11.0 software. Relative normalization of the MTR and preservation or relative increase of NM levels is determined in the rHIgM12 treated groups as compared to the control groups. A 10% increase in preserved NAA in any rHIgM12 treated group compared to control groups is considered an improvement. Excitatory neurotransmitters such as glutamate and glycine (35) have been reported to be present in high levels following cerebral ischemia. Since MRS spectroscopy is a versatile technique, we also quantify other metabolites such as lactate, myo-inositol, choline, creatine, glycine and glutamate.
Blood Brain Barrier Assessment
The proportion of rHIgM12 that crosses blood-brain barrier (BBB) is determined in the photo-thrombotic RB stroke model. There has been a debate as to whether large IgM molecules can enter the CNS. A generally accepted dogma is that IgMs with a molecular weight of close to 1 million are too large to cross the BBB from the circulation to enter the CNS (36, 37). However, there is accumulating evidence some IgMs can cross the BBB. It has been shown that rHIgM12 can enter the CNS of normal uninfected mice as well as TMEV infected mice (see
Isotopically labeled (35S) rHIgM12 is produced and validated for binding to the surface of neurons. rHIgM12 at effective dose or an isotype control IgM or a control non-specific IgG are administered i.v., to groups of 3 mice per time point following induction of cerebral ischemia. Normal CD-1 mice without ischemia serve as control. The experiment is carried out three times using a total of 144 mice (3 mice per group for a total of 5 time points and 3 groups plus a group of 3 non-treated mice, repeated 3 times).
The percentage of 35S that crosses the BBB and is found in brain/spinal cord parenchyma at 4, 8, 24, 48 and 72 hr post injection is determined. In addition, we determine the site of 35S localization in the brain/spinal cord using autoradiography techniques published by our laboratory (38). We have proposed that rHIgM12 acts directly on the nervous system, crossing the BBB after peripheral injection to interact with neurons and protects them from death.
Neuron Cultures
rHIgM12 neuro-protection is also assessed in in vitro ‘ischemia-like’ neuron culture assay. Demonstrating efficacy of rHIgM12 in protecting neurons in an in vitro environment will address concerns that a neuron-binding autoantibody may be toxic to neurons. We address this by analyzing caspase levels following treatment of normal, oxygen- and/or glucose-deprived cortical neurons with rHIgM12 or with control antibodies. In addition the development of an in vitro assay will provide necessary tools for future signaling studies.
Damage following cerebral ischemia might occur by several different mechanisms. Reagents that are neuro-protective for one type of damage are not necessarily protective for all types (39). We establish neurotoxicity assays using glucose deprivation (GD), oxygen deprivation (OD) and combined OD and GD (OGD), insults similar to those observed following cerebral ischemia. We have carried out analogous assays using hydrogen peroxide (
Dissociated cell cultures of neocortical fragments are established from 16-day CD-1 mouse embryos. Approximately 95% of the cells in such cultures are neurons, and the remaining cells are astrocytes. GD is induced by incubating neurons in glucose-free Locke's medium for 24 h. An oxygen-free chamber with 95% N2, 5% CO2 atmosphere is used to induce OD (neurons are incubated in regular medium for 12 hr) and OGD (neurons are incubated in glucose-free Locke's medium for 12 hr). Neurons are incubated in the presence of culture medium alone, or culture medium supplemented with rHIgM12 (at effective dose), or control IgM or GM1. The experiment is performed three times independently in triplicates using coded treatments on different days to avoid bias.
The primary end point is neuronal cell viability, which is determined by a mitochondrial activity assay using Alamar blue solution. Neuronal cultures are analyzed for activated caspases using the FLICA Apoptosis Detection Kit. Two different fluorescence detection methods are used: fluorescence microscopy for qualitative analysis; and 96-well micro-titer plate fluorometry for quantitation. Cell survival is evaluated by incubating the cells for 30 min with Hoechst stain and read using a UV-filter with excitation at 365 nm and emission at 480 nm. When cells are viewed through a fluorescence microscope, apoptotic cells fluoresce red, while non-apoptotic cells appear mostly unstained. Cells in more advanced stages of apoptosis appear as brighter red than cells in earlier stages. Using a fluorescence plate reader (with a black micro-titer plate), apoptosis is quantitated as the amount of red fluorescence emitted from FLICA probes bound to caspases. ANOVA is used to compare significant differences between groups. The results from this experiment will help determine downstream signaling events that are involved in neuro-protection.
To further assess the effects and capability of neuroactive antibody, particularly antibody IgM12, in cells and under conditions relevant and mimicking stroke, myocardial infarction or ischemia, studies were undertaken to evaluate antibodies under normoxic and hypoxic conditions. Hypoxic conditions in culture serve to imitate aspects of oxygen deprivation which results from stroke and ischemia in clinical scenarios. Normoxic cultures were first evaluated for various markers in mixed glial cultures. Relevant markers were then evaluated under hypoxic conditions, with and without neuroactive and control antibodies to evaluate effects and capabilities.
Normoxic Conditions
To evaluate normal or normoxic conditions, mixed glial cultures were grown for 4 days in FBS (10%) containing medium and treated for 7 days in chemically defined medium with remyelination-promoting IgM rHIgM22, regenerative mAb rHIgM12, isotype controls sHIgM116 (10 μg/ml each) or medium only. Medium with fresh antibodies was exchanged every second day. The results are depicted in
OPC-microglial co-cultures were then cultured in astrocyte-conditioned medium with remyelination promoting mAbs A2B5, O4, O1, 78.09, 94.03, rHIgM22, regenerative mAb rHIgM12, isotype controls (LEAF, 5A5, ChromPure IgM, rHIgM42, sHIgM14, sHIgM24, sHIgM26) (10 μg/ml each) or medium. Medium with fresh antibodies was exchanged every second day. Representative Western blots in
The above normoxic data demonstrate that (i) remyelination promoting mAbs (A2B5, O4, O1, 78.09, 94.03) or regenerative mAb rHIgM12 do not induce OPC differentiation or survival compared to isotype controls in OPC/OL-microglia co-cultures; (ii) soluble factors in astrocyte-conditioned medium were not sufficient to stimulate differences between treatment groups; (iii) remyelination promoting and regenerative mAbs did not activate microglia (CD68, Lyn) in the absence of astrocytes; (iv) soluble astrocytic factors seem to be sufficient to mediate OPC proliferation by rHIgM22 (Ki-67, histone H3) after 6 days of IgM-treatment.
In the next set of normoxic studies, mixed glial cultures were grown and treated as described previously (
Hypoxic Conditions
The molecular effects of hypoxia on mixed glia cultures were then compared to normoxic cultures. Mixed glial cultures were grown for 4 days in FBS (10%) containing medium and treated for 7 additional days in chemically defined medium under hypoxia (3% O2) compared to normoxic conditions (21% O2). Representative Western blots (
Having verified the hypoxic model, treatment of hypoxic cultures with regenerative antibody IgM12 was then undertaken to assess antibody effects in conditions relevant to and mimicking stroke, infarction and ischemia effects. Mixed glial cultures were grown for 4 days under normoxic conditions in FBS (10%) containing medium and subsequently treated for 1-7 days in chemically defined medium with human regenerative antibody rHIgM12 or medium only under hypoxia (3% O2). Representative Western blots (
The molecular outcome of rHIgM12 under hypoxia versus normoxia was assessed by direct comparison of rHIgM12-mediated effects on mixed glia under hypoxia compared to normoxia. Mixed glia was cultured as described before and treated in chemically defined medium for 7 days with rHIgM12, rHIgM22 or medium only under hypoxic or normoxic conditions. Representative Western blots
Hypoxic conditions were evaluated in animals to check validity and consistency of the culture markers. A molecular analysis of hypoxic and normoxic cortices from P13 old neonatal B16 mice was performed. C57/Bl6 neonatal mice were cross-fostered by CD1 dams and exposed to hypoxia (10% O2) for 4 days from P3 to P7. Mice were subsequently exposed to room air for an additional 6 days and sacrificed at P13. RNA was isolated from cortices in both treatment groups (normoxia and hypoxia mice) and probed for myelin markers PLP1, MOG, MBP1, oligodendrocyte progenitor markers PDGFαR and Olig-1, astrocytic marker GFAP, neuronal markers Nestin and β3-tubulin, hypoxia-inducible factor 1α and the sarcospan protein SSPN. Expression levels were analyzed by RT-PCR and results normalized to levels of β-actin. RT-PCR analysis of the markers in cortices from hypoxic and normoxic C57/Bl6 neonates at P13 was conducted and the results are shown in
To evaluate antibody access and localization for intervention after a stroke or ischemic event, a stroke animal model was utilized with IP administration of monoclonal antibody. A stroke was induced in mice, radio-labeled antibody administered, and then animal tissues evaluated for antibody by determining radio-labeling at periods up to 24 hours post administration. Brain (cortex) containing the stroke lesion was evaluated, as well as cerebellum, spinal cord, liver, spleen, kidney and blood serum.
Stroke was induced in the right cerebral cortex in three adult CD-1 mice using the photo activated Rose Bengal protocol described above and three other mice received a sham stroke procedure, Rose Bengal but no light activation. At 30 to 40 min post stroke, 10 million cpm of 3'S labeled rHIgM12, corresponding to about 60 ug of IgM, was administered intraperitoneally to each mouse in a volume of 500 ul saline. At 6, 12 and 24 hr post IgM administration or treatment, blood was collected from mice, the vasculature washed with 30 ml of saline and tissues acutely collected. For analysis of radiolabel in tissue, the right front cortex of the brain containing the lesion area was removed as a 75 mg tissue block. Tissue was dissolved in Solvable (PerkinElmer) and cpm determined in UltraGold liquid scintillation cocktail following the manufacturer's protocols. A portion of other tissues were removed, weighed and processed according to the ratios provided by Perkin Elmer. The results are depicted in
Although this study utilized a single mouse at each tine point, it is notable that rHIgM12 accumulated in CNS tissue over 24 hr, while in contrast rHIgM12 levels fell in tissues responsible for blood metabolism, and in serum itself. The high level of rHIgM12 in the cortex (first panel denoted Brain in
This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present disclosure is therefore to be considered as in all aspects illustrated and not restrictive, the scope of the invention being indicated by the appended Claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.
Various references are cited throughout this Specification, each of which is incorporated herein by reference in its entirety.
The invention described herein was supported in whole or in part by the National Institutes of Health (Grant Nos. R01 NS 24180, R01 NS 32129, R01 CA104996, R01 CA096859), and the National Multiple Sclerosis Society (Grant No. CA 1011 A8-3) The United States Government has certain rights in the invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2013/036947 | 4/17/2013 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61625628 | Apr 2012 | US |
