Patent Application
20200254019
The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Feb. 24, 2020, is named “16785-194-1_2020-02-24_Sequence-Listing_ST25” and is 4.00 kb in size.
The present invention relates to a pharmaceutical preparation for treating internal inflammatory conditions, preferably internal conditions associated with ischemia.
Hypoxia, a state of reduced oxygen, can occur when the lungs are compromised or blood flow is reduced. Ischemia, reduction in blood flow, can be caused by the obstruction of an artery or vein by a blood clot (thrombus) or by any foreign circulating matter (embolus) or by a vascular disorder such as atherosclerosis. Reduction in blood flow can have a sudden onset and short duration (acute ischemia) or can have a slow onset with long duration or frequent recurrence (chronic ischemia). Acute ischemia is often associated with regional, irreversible tissue necrosis (an infarct), whereas chronic ischemia is usually associated with transient hypoxic tissue injury. If the decrease in perfusion is prolonged or severe, however, chronic ischemia can also be associated with an infarct. Infarctions commonly occur in the spleen, kidney, lungs, brain and heart, producing disorders such as intestinal infarction, pulmonary infarction, ischemic stroke and myocardial infarction.
Pathologic changes in ischemic disorders depend on the duration and severity of ischemia, and on the length of patient survival. Necrosis can be seen within the infarct in the first 24 h and an acute inflammatory response develops in the viable tissue adjacent to the infarct with leukocytes migrating into the area of dead tissue. Over succeeding days, there is a gradual breakdown and removal of cells within the infarct by phagocytosis and replacement with a collagenous or glial scar.
Hypoperfusion or infarction in one organ often affects other organs. For example, ischemia of the lung, caused by, for example, a pulmonary embolism, not only affects the lung, but also puts the heart and other organs, such as the brain, under hypoxic stress. Myocardial infarction, which often involves coronary artery blockage due to thrombosis, arterial wall vasospasms, or viral infection of the heart, can lead to congestive heart failure and systemic hypotension. Secondary complications such as global ischemic encephalopathy can develop if the cardiac arrest is prolonged with continued hypoperfusion. Cerebral ischemia, most commonly caused by vascular occlusion due to atherosclerosis, can range in severity from transient ischemic attacks (TIAs) to cerebral infarction or stroke. While the symptoms of TIAs are temporary and reversible, TIAs tend to recur and are often followed by a stroke.
Occlusive arterial disease includes coronary artery disease, which can lead to myocardial infarction, and peripheral arterial disease, which can affect the abdominal aorta, its major branches, and arteries of the legs. Peripheral arterial disease includes Buerger's disease, Raynaud's disease, and acrocyanosis. Although peripheral arterial disease is commonly caused by atherosclerosis, other major causes include, e.g., diabetes, etc. Complications associated with peripheral arterial disease include severe leg cramps, angina, abnormal heart rhythms, heart failure, heart attack, stroke and kidney failure.
Ischemic and hypoxic disorders are a major cause of morbidity and mortality. Cardiovascular diseases are responsible for 30% of deaths worldwide. Among the various cardiovascular diseases, ischemic heart disease and cerebrovascular diseases cause approximately 17% of deaths.
Currently, treatment of ischemic and hypoxic disorders is focused on relief of symptoms and treatment of causative disorders. For example, treatments for myocardial infarction include nitroglycerin and analgesics to control pain and relieve the workload of the heart. Other medications, including digoxin, diuretics, amrinone, beta-blockers, lipid-lowering agents and angiotensin-converting enzyme inhibitors, are used to stabilize the condition, but none of these therapies directly address the tissue damage produced by the ischemia and hypoxia.
Due to deficiencies in current treatments, there remains a need for methods that are effective in treating conditions involving hypoxia. There is also a need for methods that are effective in the prevention of tissue damage caused by ischemia that occurs due to, e.g., atherosclerosis, diabetes and pulmonary disorders.
Conditions associated with ischemia and hypoxia are usually accompanied by inflammation. Therefore, means and methods are needed which also reduce inflammation.
It is an object of the present invention to provide means which allow the efficient treatment of internal inflammatory conditions, preferably conditions associated with ischemia.
The present invention relates to a pharmaceutical preparation for treating an internal inflammatory condition, preferably an internal condition associated with ischemia, comprising
a) a physiological solution comprising peripheral blood mononuclear cells (PBMCs), which consist of lymphocytes (T cells, B cells, NK cells) and monocytes, or a subset thereof, or
b) a supernatant of the solution a), wherein the solution a) is obtainable by cultivating PBMCs or a subset thereof in a physiological solution free of PBMC-proliferating and PBMC-activating substances for at least 1 h.
It turned out that the administration of a pharmaceutical preparation as defined above to a patient suffering from an internal inflammatory condition, preferably an internal condition associated with ischemia, results in an alleviation of the respective symptoms and in a healing process.
The pharmaceutical preparation of the present invention comprises cultivated PBMCs or a subset thereof and/or the supernatant in which the PBMCs have been cultivated. In the course of the cultivation of PBMCs these cells express and secrete substances like cytokines which differ from those expressed and secreted in activated PBMCs. This means that the secretome of PBMCs of the present invention is different from the secretome of activated PBMCs. The cells of the present invention undergo a non-cell-surface moiety triggered secretome production. Therefore it is surprising that PBMCs which have not been contacted with PBMC activating substances like PHA or LPS can be employed to treat internal inflammatory conditions, in particular ischemic conditions, which shows that the secretome of these cells comprises substances supporting the treatment of such or similar conditions.
The PBMCs according to the present invention are obtainable by cultivation in a physiological solution which does not comprise PBMC-proliferating and PBMC-activating substances. However, the PBMCs are incubated in the physiological solution for at least 1 h. This minimum time of cultivation is required to let the PBMCs secrete cytokines and other beneficial substances.
PBMCs part of the preparation according to the present invention can be obtained from whole blood using methods known in the art such as Ficoll gradient, hypotonic lysis etc. These methods are well known in the art.
PBMCs of the pharmaceutical preparation may be obtained from a pool of donors or from the same individual to which the preparation will be administered.
The PBMCs or the subsets thereof are present in the preparation according to the present invention in their viable form.
The physiological solution from which the supernatant is obtained comprises at least 500, preferably at least 1000, more preferably at least 105, even more preferably at least 106, cells per mL solution or per dosage unit.
The preparation of the present invention may comprise at least 500, preferably at least 1000, more preferably at least 105, even more preferably at least 106, PBMCs per mL or per dosage unit.
“Physiological solution”, as used herein, refers to a liquid solution in which PBMCs are cultivated prior to their use in the pharmaceutical preparation according to the present invention.
“Physiological solution” refers also to a solution which does not lead to the death of PBMCs within an hour, preferably within 30 min. If the number of viable PBMCs is decreasing in a solution by 75%, more preferably by 90% within one hour, preferably within 30 min, the solution is not considered to be a “physiological solution” as defined herein. The “physiological solution” does not lead to a spontaneous lysis of PBMCs when contacted with said solution.
In this context the step of “cultivating” or “culturing” comprises or consists of the step of “incubating”, a step in which the cells are contacted with a solution for a defined time (at least 1 h, preferably at least 4 h, more preferably at least 8 h, even more preferably at least 12 h) under conditions which are regularly used for cultivating PBMCs.
The term “condition associated with ischemia” in the context of the present invention can be used interchangeably with the term “ischemic conditions” and denotes any condition, disease or disorder in which regions of the human or animal body are deprived of adequate oxygen supply resultant damage or dysfunction of tissue. A pathological condition may be characterized by reduction or abolition of blood supply within an organ or part of an organ, which may be caused by the constriction or obstruction of a blood vessel. Such conditions are collectively referred to herein by the term “ischemia” or “ischemia related conditions” or “condition related to ischemia”. In heart disease, for instance, ischemia is often used to describe the heart muscle that is not getting the proper amount of oxygen-rich blood because of narrowed or blocked coronary arteries. The symptoms of ischemia depend on the organ that is “ischemic”. With the heart, ischemia often results in angina pectoris. In the brain, ischemia can result in a stroke. Ischemia conditions are accompanied by inflammation.
Non-limiting examples for pathological conditions which relate to inflammation, in particular to ischemia, include wounds, myocardial ischemia, limb ischemia, tissue ischemia, ischemia-reperfusion injury, angina pectoris, coronary artery disease, peripheral vascular disease, peripheral arterial disease, stroke, ischemic stroke, chronic wounds, diabetic wounds, myocardial infarction, congestive heart failure, pulmonary infarction, skin ulcer, etc.
Notwithstanding the above, a pathological condition in the context of the invention may be characterized by damage or dysfunction of endothelial cells, i.e. wound. Non-limiting examples of wounds which may be treated by the use of the preparation according to the present invention are chronic wounds, diabetic wounds, ulcer, burns, inflammatory skin disease and bowel disease.
The terms “internal condition”, “internal inflammatory condition” and “internal conditions associated with ischemia” relate to conditions and diseases which occur inside the body of an individual that are caused by acute or latent hypoxia and inflammation in mammal end organs necessary for optimal functioning (e.g. bone, heart, liver, kidney, cerebrum, skin integrity).
“Physiological solution”, as used herein, refers to a solution exhibiting an osmotic pressure which does not lead to the destruction of the PBMCs or subsets thereof and can be directly administered to an individual.
The term “free of PBMC-proliferating and PBMC-activating substances” refers to the physiological solution which does not comprise substances which activate PBMCs and induce the proliferation of PBMCs or subsets thereof. Non-limiting examples of such substances include PHA, LPS, and the like.
According to a preferred embodiment of the present invention the inflammatory condition is selected from the group of mammal diseases that are related to hypoxia and inflammation of functional end organs.
According to a particularly preferred embodiment of the present invention the internal inflammatory condition, preferably the internal condition associated with ischemia, is selected from the group consisting of myocardial ischemia, limb ischemia, tissue ischemia, ischemia-reperfusion injury, angina pectoris, coronary artery disease, peripheral vascular disease, peripheral arterial disease, stroke, ischemic stroke, myocardial infarction, congestive heart failure, trauma, bowel disease, mesenterial infarction, pulmonary infarction, bone fracture, tissue regeneration after dental grafting, auto-immune diseases, rheumatic diseases, transplantation allograft and rejection of allograft.
The subset of peripheral blood mononuclear cells (PBMCs) is preferably T cells, B cells or NK cells (i.e., lymphocytes). Of course it is also possible to use combinations of these lymphocyte cells: T cells and B cells; T cells and NK cells; B cells and NK cells; T cells, B cells and NK cells. Methods for providing and isolating said cells are known.
It surprisingly turned out that the PBMCs of the present invention can be cultivated in any kind of solution provided that said solution does not comprise substances which are not pharmaceutically acceptable, lead to an immediate death of the PBMCs, activate PBMCs and stimulate the proliferation of PBMCs (as defined above). Therefore, the solution to be used at least exhibits osmotic properties which do not lead to lysis of the PBMCs. The physiological solution is preferably a physiological salt solution, preferably a physiological NaCl solution, whole blood, a blood fraction, preferably serum, or a cell culture medium.
The cell culture medium is preferably selected from the group consisting of RPMI, DMEM, X-vivo and Ultraculture.
According to a particularly preferred embodiment of the present invention the cells of the present invention are cultivated under stress inducing conditions.
The term “under stress inducing conditions”, as used herein, refers to cultivation conditions leading to stressed cells. Conditions causing stress to cells include among others heat, chemicals, radiation, hypoxia, osmotic pressure (i.e. non-physiological osmotic conditions) etc.
Additional stress to the cells of the present invention leads to a further increase of the expression and secretion of substances beneficial for treating internal inflammatory conditions, preferably internal conditions associated with ischemia.
According to a preferred embodiment of the present invention the stress inducing conditions include hypoxia, ozone, heat (e.g. more than 2° C., preferably more than 5° C., more preferably more than 10° C., higher than the optimal cultivation temperature of PBMCs, i.e. 37° C.), radiation (e.g. UV radiation, gamma radiation), chemicals, osmotic pressure (i.e. osmotic conditions which are elevated at least 10% in comparison to osmotic conditions regularly occurring in a body fluid, in particular in blood), pH shift or combinations thereof.
If radiation is used to stress the PBMCs of the present invention the cells are preferably irradiated with at least 10 Gy, preferably at least 20 Gy, more preferably at least 40 Gy, whereby as source Cs-137 Cesium is preferably used.
According to a preferred embodiment of the present invention the non-activated PBMCs or a subset thereof are cultivated in a medium for at least 4 h, preferably for at least 6 h, more preferably for at least 12 h.
The pharmaceutical preparation according to the present invention can be administered in various ways depending on the condition to be treated. Therefore, said preparation is preferably adapted for subcutaneous administration, intramuscular administration, intra-organ administration (e.g. intramyocardial administration) and intravenous administration.
A pharmaceutical preparation according to the present invention may comprise pharmaceutically acceptable excipients such as diluents, stabilizers, carriers etc. Depending on the administration route the preparation according to the present invention is provided in a respective dosage form: injection solution, etc. Methods for preparing the same are well known to the skilled artisan.
In order to increase the shelf-life of the preparation according to the present invention the solution a) or the supernatant b) is lyophilized. Methods for lyophilizing such preparations are well known to the person skilled in the art.
Prior its use the lyophilized preparation can be contacted with water or an aqueous solution comprising buffers, stabilizers, salts etc.
Another aspect of the present invention relates to the use of a preparation as defined above for the manufacture of a medicament for treating an internal inflammatory condition, preferably an internal condition associated with ischemia.
Yet another aspect of the present invention relates to a method for preparing a pharmaceutical preparation as disclosed herein comprising the steps of
a) providing peripheral blood mononuclear cells (PBMCs) or a subset thereof (e.g., lymphocytes or subset thereof),
b) culturing the cells of step a) in a physiological solution free of PBMC-proliferating and PBMC-activating substances for at least 1 h,
c) isolating the cells of step b) and/or the supernatant thereof, and
d) preparing the pharmaceutical preparation using the cells and/or the supernatant of step c).
The preparation according to the present invention can be obtained by incubating or culturing PBMCs in a physiological solution for at least 1 h, preferably at least 4 h, more preferably at least 8 h, even more preferably at least 12 h. In the course of this step the PBMCs begin to synthesize and to secrete substances which are useful in the treatment of internal inflammatory conditions. Prior, after and in the course of the culturing step the cells are not activated by adding PBMC activating substances like PHA or LPS. After the cultivation step the cells and/or the supernatant of the culture is isolated to be further used in the preparation of the final pharmaceutical preparation. As discussed above the pharmaceutical preparation may comprise cultivated PBMCs, the supernatant of the culture in which said cells had been incubated or both the cultivated PBMCs as well as the culture medium.
According to a preferred embodiment of the present invention the cells are subjected to stress inducing conditions before or in the course of step b), wherein said stress inducing conditions include hypoxia, ozone, heat, radiation, chemicals, osmotic pressure (e.g. induced by the addition of salt, in particular NaCl, in order to give an osmotic pressure higher than in blood), pH shift (i.e. pH change by adding acids or hydroxides to give a pH value of 6.5 to 7.2 or 7.5 to 8.0) or combinations thereof.
According to a preferred embodiment of the present invention the cells are irradiated before or in the course of step b) with at least 10 Gy, preferably at least 20 Gy, more preferably at least 40 Gy, with ozone, with elevated temperature or with UV radiation.
Another aspect of the present invention relates to a preparation obtainable by a method as described above.
Another aspect of the present invention relates to a method for treating internal inflammatory conditions, preferably internal conditions associated with ischemia, by administering to an individual in need thereof an appropriate amount of the pharmaceutical preparation according to the present invention. Depending on the condition to be treated the preparation of the present invention is administered intramuscularly, intravenously, intra-organly (e.g. intramyocardially) or subcutaneously.
In a preferred embodiment of the present invention the pharmaceutical preparation comprises at least 500, preferably at least 1000, more preferably at least 105, even more preferably at least 106 PBMCs per mL obtainable by a method as outlined above. Correspondingly at least 500, preferably at least 1000, more preferably at least 105, even more preferably at least 106, PBMCs are administered to an individual to be treated.
The present invention is further illustrated by the following figures and examples, however, without being restricted thereto.
Acute myocardial infarction (AMI) often leads to congestive heart failure. Despite current pharmacological and mechanical revascularization no effective therapy is defined experimentally to replace infarcted myocardium. Integral components of the remodeling process after AMI are the inflammatory response and the development of neo-angiogenesis after AMI. These processes are mediated by cytokines and inflammatory cells in the infarcted myocardium that phagocytose apoptotic and necrotic tissue and initiate homing of interstitial dendritic cells (IDC) and macrophages. Clinical trials aimed to attenuate AMI induced inflammatory response were abducted since systemic immune suppression (steroids) led to increased infarct size and delayed myocardial healing. From these data it was concluded that inflammatory response after AMI is responsible for tissue stabilization and scar formation. A new field in regenerative cardiovascular medicine emerged when investigators observed that distant stem cells sense sites of damage and promote structural and functional repair. By utilizing this approach, Orlic et al. injected c-kit positive endothelial progenitor cells (EPC) into the boarder zone of experimental AMI and increased neo-angiogenesis and regeneration of myocardial and vascular structures. This work ignited a plethora of publications that demonstrated a regenerative potential of “cell based therapy”, however it still remains elusive whether this therapeutic effect is caused by the transplanted cells themselves, recruitment of resident cardiac stem cells, or by activation of, as yet, unidentified paracrine and immunologic mechanisms. Ischemia in infarcted myocardium causes apoptotic processes and initiates alterations of cell surface lipids on dying cells. The best-characterized modification is the loss of phospholipid asymmetry and exposure of phosphatidylserine (PS). These PS are recognized by macrophages and dendritic cells (antigen presenting cells, APC) via ligands such as thrombospondin, CD14 and CD36. Under physiological conditions these receptors serve to engulf apoptotic and necrotic debris and initiate a silent “clean up” process. This process of phagocytosis by APC leads to a phenotypic anti-inflammatory response as determined by augmented IL-10 and TGF-β production and impaired APC function. Of clinical relevance are reports that demonstrated that infusion of apoptotic cells lead in a hematopoietic cell (HC) transplantation model to allogeneic HC engraftment and to a delay of lethal acute graft-versus-host disease (GVHD). Moreover, in solid organ transplantation models infusion of donor apoptotic cells increased heart graft survival. Contrary to inflammation and relevant to progenitor cell recruitment from bone marrow (BM) it was shown that opsonization of apoptotic cells elicits enhanced VEGF and CXC8/IL-8 production of APC. In addition to the latter cytokines MMP9 was also identified to be vital for EPC recruitment and liberation from the bone marrow.
The current “status quo” in AMI treatment is directed toward early reperfusion and reopening the acute occluded coronary artery and that myocardial inflammation post infarction is perceived beneficiary despite this condition increases myocardial damage and counteracts endogenous repair mechanisms.
For the in vivo experiments blood was drawn from healthy young volunteers. Apoptosis was induced by Cs-137 Cesium irradiation with 60 Gy (human PBMC) or with 45 Gy for in vivo (rat PBMC) experiments. Cells were resuspended in serum free Ultra Culture Medium (Cambrex Corp., USA) containing 0.2% gentamycin-sulfate (Sigma Chemical Co, USA), 0.5% β-mercapto-ethanol (Sigma, USA), 1% L-glutamine (Sigma, USA) and cultured in a humidified atmosphere for 24 h for in vitro experiments (concentration of cells, 1×106 mL). Induction of apoptosis was measured by Annexin V-fluorescein/propidium iodide (FITC/PI) co-staining (Becton Dickinson, USA) on a flow cytometer. Annexin-positivity of PBMCs was determined to be >70% and are consequently termed IA-PBMC. Non-irradiated PBMCs served as controls and are termed viable-PBMC. From both experimental settings supernatants were collected and served as experimental entities as described below (SN-viable-PBMC, SN-IA-PBMC).
Human PBMCs and monocytes (purity >95%) were separated using a magnetic bead system (negative selection Miltenyi Biotec, USA). PBMCs and monocytes were co-incubated for 4 h with different concentrations of apoptotic autologous PBMCs (annexin positivity >70%) and Lipopolysaccharide (1 ng/mL LPS; Sigma Chemical Co, USA). Supernatants were secured and kept frozen at −80° C. until further tests. IL-6 and IL-1β release was determined using commercially available ELISA kits (BenderMedSystems, Austria).
PBMCs were isolated from heparinized whole blood of healthy donors by standard density gradient centrifugation with Ficoll-Paque (GE Healthcare Bio-Sciences AB, Sweden). T cells and monocytes were separated by magnetic sorting using the MACS technique (Miltenyi Biotec). Purified T cells were obtained through negative depletion of CD11b, CD14, CD16, CD19, CD33, and MEC class II-positive cells with the respective monoclonal antibody. Monocytes were enriched by using the biotinylated CD14 mAb VIM13 (purity 95%). DCs were generated by culturing purified blood monocytes for 7 days with a combination of GM-CSF (50 ng/mL) and IL-4 (100 UmL). Subsequently, DCs were differently stimulated. Maturation was induced either by adding 100 ng/mL LPS from Escherichia coli (serotype 0127-B8, Sigma Chemie) for 24 h alone or by adding LPS for 2 h and further culturing the dendritic cells with apoptotic cells in a 1:1 ratio for 22 h. Additionally, DCs were treated with apoptotic cells alone (1:1) for 24 h. For the mixed leukocyte reaction (MLR), allogenic, purified T cells (1×105/well) were incubated in 96-well cell culture plates (Corning Costar) with graded numbers of differently stimulated DCs for 6 days. The assay was performed in triplicate. Proliferation of T cells was monitored by measuring [methyl-3H]thymidine (ICN Pharmaceuticals) incorporation, added after 5 days. Cells were harvested after 18 h and incorporated [methyl-3H]thymidine was detected on a microplate scintillation counter.
Cell Culture, RNA Isolation and cDNA Preparation of Viable PBMCs, IA-PBMCs, and SN Exposed Fibroblasts
IA-PBMCs, viable-PBMCs (1×106 cells, both conditions cultured for 24 h in Ultra Culture Medium), and fibroblasts exposed to SN-viable-PBMC/SN-IA-PBMC were investigated (1×105 fibroblasts obtained from Cascade Inc. (USA) were cultured in Dulbecco's modified Eagle medium (DMEM, Gibco BRL, USA) supplemented with 10% fetal bovine serum (FBS, PAA, Austria), 25 mM L-glutamine (Gibco, BRL, USA) and 1% penicillin/streptomycin (Gibco) and seeded in 12 well plates; fibroblasts were co-incubated with SN-viable-PBMC, SN-IA-PBMC for 4 and 24 h respectively). After RNA extraction of PBMCs and fibroblasts (using RNeasy, QIAGEN, Austria) following the manufacturer's instruction, cDNAs were transcribed using the iScript cDNA synthesis kit (BioRad, USA) as indicated in the instruction manual.
mRNA expression was quantified by real time PCR with LightCycler Fast Start DNA Master SYBR Green I (Roche Applied Science, Penzberg, Germany) according to the manufacturer's protocol. The primers for VEGF were: forward: 5′-CCCTGATGAGATCGAGTACATCTT-3′ (SEQ ID NO: 1), reverse: 5′-ACCGCCTCGGCTTGTCAC-3′ (SEQ ID NO: 2); for IL-8 forward: 5′-CTCTTGGCAGCCTTCCTGATT-3′ (SEQ ID NO: 3), reverse: 5′-TATGCACTGACATCTAAGTTCTTTAGCA-3′ (SEQ ID NO: 4); for MMP9 forward: 5′-GGGAAGATGCTGGTGTTCA-3′ (SEQ ID NO: 5), reverse: 5′-CCTGGCAGAAATAGGCTTC-3′ (SEQ ID NO: 6) and for β-2-microglobulin β 2M, forward: 5′-GATGAGTATGCCTGCCGTGTG-3′ (SEQ ID NO: 7), reverse: 5′-CAATCCAAATGCGGCATCT-3′ (SEQ ID NO: 8). The relative expression of the target genes was calculated by comparison to the house keeping gene β2M using a formula described by Wellmann et al. (Clinical Chemistry. 47 (2001) 654-660, 25). The efficiencies of the primer pairs were determined as described (A. Kadl, et al. Vascular Pharmacology. 38 (2002) 219-227).
Release of Pro-Angiogenetic Factors and MMP9 by Viable PBMCs and IA-PBMCs after Culture
IA-PBMCs (5×105) and viable PBMCs were incubated in a humidified atmosphere for 24 h. Supernatants were collected after 24 h and immediately frozen at −80° C. until evaluation. Lysates of respective cells served as controls. Release of pro-angiogenetic factors (VEGF-A, CXCL-8/IL-8, GMCSF, GCSF) and MMP9, an accepted liberating factor of c-kit cells, were analyzed utilizing ELISA (R&D, USA) following the manufacturer's instructions. Plates were read at 450 nm on a Wallac Multilabel counter 1420 (PerkinElmer, USA).
Syngeneic rat PBMCs for in vivo experiments were separated by density gradient centrifugation from whole-blood obtained from prior heparinized rats by punctuation of the heart. Apoptosis was induced by Cs-137 Cesium irradiation with 45 Gy for in vivo experiments and cultured for 18 h as described above. (annexin staining >80% IA-PBMC, annexin staining <30% viable PBMC, 1×106/mL).
Myocardial infarction was induced in adult male Sprague-Dawley rats by ligating the LAD as previously described (Trescher K, et al. Cardiovasc Res. 2006: 69(3): 746-54). In short, animals were anesthetized intraperitoneally with a mixture of xylazin (1 mg/100 g bodyweight) and ketamin (10 mg/100 g bodyweight) and ventilated mechanically. A left lateral thoracotomy was performed and a ligature using a 6-0 prolene was placed around the LAD beneath the left atrium. Immediately after the onset of ischemia 8×106 apoptotic PBMCs suspended in 0.3 mL cell culture medium were infused through the tail vein. Infusion of cell culture medium alone, viable PBMCs, and sham operation respectively served in this experimental setting as negative controls. The rat experimental design is shown in
8×106 syngeneic rat PBMCs were labelled with 15 μM Carboxy-fluorescein diacetate succinimidyl ester (CFSE, Fluka Bio-Chemika, Buchs, Switzerland) at room temperature for 10 min. Labelling was stopped by the addition of fetal calf serum (FCS). Apoptosis was induced (annexin V>70%) and cells were injected after ligation procedure. 72 h after operation rats were sacrificed and liver, spleen and heart were processed following a standard procedure for frozen sections (n=4). Samples were analyzed by confocal laser scanning microscopy (ZEISS LSM 510 laser scanning microscope, Germany) as described previously (Kerjaschki D, J Am Soc Nephrol. 2004; 15: 603-12).
All animals were sacrificed either 72 h or 6 weeks after experimental infarction. Hearts were explanted and then sliced at the level of the largest extension of infarcted area (n=8-10). Slices were fixed with 10% neutral buffered formalin and embedded in paraffin for (immune-) histological staining. The tissue samples were stained with hematoxylin-eosin (H&E) and elastic van Gieson (evg). Immunohistological evaluation was performed using the following antibodies directed to CD68 (MCA 341R, AbD Serotec, UK), VEGF (05-443, Upstate/Milipore, USA), Flk-1 (sc-6251, Santa Cruz Biotechnology, USA), CD34 (sc-52478, Santa Cruz Biotechnology, USA), c-kit (sc-168, Santa Cruz Biotechnology, USA), 5100 beta (sc-58841, Santa Cruz Biotechnology, USA). Tissue samples were evaluated on an Olympus Vanox AHBT3 microscope (Olympus Vanox AHBT3, Olympus Optical Co. Ltd., Japan) at 200× magnification and captured digitally by using a ProgRes Capture-Pro C12 plus camera (Jenoptik Laser Optik Systeme GmbH, Germany).
In order to determine the size of the infarcted area, Image J planimetry software (Rasband, W. S., Image J, U. S. National Institutes of Health, USA) was used. The extent of infarcted myocardial tissue (% of left ventricle) was calculated by dividing the area of the circumference of the infarcted area by the total endocardial and epicardial circumferenced areas of the left ventricle. Planimetric evaluation was carried out on tissue samples stained with evg for better comparison of necrotic areas. Infarct size was expressed as percent of total left ventricular area.
Six weeks after induction of myocardial infarction rats were anaesthetized with 100 mg/kg Ketamin and 20 mg/kg Xylazin. The sonographic examination was conducted on a Vivid 5 system (General Electric Medical Systems, USA). Analyses were performed by an experienced observer blinded to treatment groups to which the animals were allocated (EW). M-mode tracings were recorded from a parasternal short-axis view and functional systolic and diastolic parameters were obtained. Ventricular diameters and volumes were evaluated in systole and diastole. Fractional shortening was calculated as follow: FS (%)=((LVEDD-LVESD)/LVEDD)×100%
Statistical analysis was performed using SPSS software (SPSS Inc., USA). All data are given as mean±standard of the mean. Normal distribution was verified using the Kolmogorov-Smirnov test. Paired two-sided t-tests for dependent, unpaired t-tests for independent variables were utilized calculating significances. Bonferroni-Holm correction was used to adjust p-values for multiple testing. P-values <0.05 were considered statistically significant.
Induction of Apoptosis with Cesium Irradiation (IA-PBMC)
In order to evaluate the immunomodulatory potential of apoptotic cells, first the cellular response to induction of apoptosis by cesium irradiation of human peripheral blood mononuclear cells (PBMC) was determined by flow cytometry utilizing Annexin-V/PI staining on a flow cytometer. Irradiation caused positivity for Annexin on PBMCs in a time dependent manner and peaked within 24 h as compared to viable PBMC. Viable cells served as controls (
Interleukin-1β and IL-6 is recognized as the predominant pro-inflammatory mediator in myocardial infarction in vivo. To test the hypothesis whether IA-PBMC has an effect on cellular response human monocytes, PBMCs were co-incubated with IA-PBMC and target cells were stimulated with LPS. A dose dependent decrease in secretion of IL-1β and IL-6 in cultures of both cell types as evaluated by ELISA was found (
IA-PBMC and Viable PBMC Evidence Increased mRNA Transcription of VEGF, IL-8/CXL8, and MMP9
To substantiate whether irradiation leads to enhanced mRNA transcription of proteins known to be related to mobilization of EPC PBMC was analyzed after separation, and after apoptosis induction (24 h). Viable PBMC served as control (viable PBMC or IA-PBMC). RNA transcription showed little difference VEGF expression as determined by RT-PCR, however a strong enhancement of IL-8/CXCL8 and MMP9. Peak induction for IL-8/CXL8 in IA-PBMC was 6 fold versus 2 fold in viable cells, and 30 fold versus 5 fold for MMP9, respectively (
IA-PBMC and Viable PBMC Secrete Paracrine Factors that Cause Endothelial Progenitor Cells (EPC) Liberation
SN derived from IA-PBMC and viable PBMC were quantified for VEGF, IL-8/CXCL8, GMCSF, GCSF and MMP9 utilizing ELISA after 24 h culture. As seen in
SN Derived from IA-PBMC and Viable PBMC Augment Pro-Angiogenic mRNA Transcription in Mesenchymal Fibroblasts
Since stromal cells in bone marrow are constitutively fibroblasts it was sought to investigate whether co-incubation of fibroblasts with SN derived from IA-PBMC and viable PBMC had the ability to increase VEGF, IL-8/CXCL8 and MMP9 mRNA transcription, factors responsible for EPC mobilization. RT-PCR was conducted at 4 and 24 h. Highest levels of induction were detected for IL-8/CXCL8 in cells cultivated in IA-PBMC SN, reaching an almost 120-fold induction at 4 h as compared to control. This response is also present at 24 h. A comparable response was found for VEGF, whereas MMP9 upregulation was predominantly found after 24 h. This data indicates that SN contains paracrine factors that enhance fibroblasts to augment mRNA products responsible for pro-angiogenic effects in the BM (
Because it could be proven that cultured IA-PBMC are both anti-inflammatory and pro-angiogenic in vitro IA-PBMC and viable PBMC were infused in an acute rat AMI model. First it was sought to determine where these cultured cells are homing after infarction. CFSE labelled IA-PBMC were injected into the rat's tail vein shortly after LAD artery ligation. A representative histology is seen in
Upon closer investigation in H.E. staining, control infarction and viable leucocytes (viable PBMC) treated AMI rats evidenced a mixed cellular infiltrate in the wound areas in accordance to granulation tissue with abundance of neutrophils, macrophages/monocytes, lymphomononuclear cells, fibroblasts and activated proliferating endothelial cells admixed to dystrophic cardiomyocytes (
Early Homing of VEGF+, Flk1+ and c-Kit+ Cells in IA-PBMC Treated AMI
Since IA-PBMC evidenced a dense monomorphic infiltrate in wound areas that consisted of medium sized monocytoid cells with eosinophilic cytoplasm and dense nuclei multiple surface markers related to neo-angiogenesis and regenerative potency were explored. This cell population identified in the H.E. staining in IA-PBMC treated AMI group stained highly positive for vascular endothelial growth factor (VEGFa), Flk-1 and c-kit (CD 117) (
In a planimetric analysis performed on EVG stained tissue samples from hearts explanted 6 weeks after myocardial infarction was induced, rats receiving saline show a collagenous scar extending to over 24.95%±3.58 (SEM) of the left ventricle with signs of dilatation. In IA-PBMC treated rats these signs were almost abrogated with infarct sizes of 5.81%±2.02 (SEM) as compared to 14.3%±1.7 (SEM) treated with viable PBMC (
Intravenous application of syngeneic cultured IA-PBMC significantly improves echocardiographic parameters as compared with viable PBMC or culture medium treated animals. Shortening fraction (SF) evidenced values of 29.16%±4.65 (SEM) in sham operated animals, 18.76%±1.13 (SEM) in medium treated AMI animals, 18.46%±1.67 (SEM) in the viable PBMC AMI group and 25.14%±2.66 (SEM) in IA-PBMC treated rats (
Analysis of end-systolic and end-diastolic diameters (LVESD, LVEDD), end-systolic and end-diastolic volumes (LVESV, LVEDV) showed a comparable pattern to the previously observed values. Saline receiving animals and viable PBMC treated rats showed LVEDD values of 10.43 mm±0.21 (SEM) and 11.03 mm±0.40 respectively, IA-PBMC rats even represented a slightly reduced left-ventricular diastolic diameter of 8.99 mm±0.32 compared to 9.47 mm 0.64 in sham operated animals. Differences in systolic diameters were less pronounced, but in the same ranking (Panel 5 (a, b, c)
These findings demonstrate that irradiated apoptotic PBMCs (IA-PBMCs) induce immune suppression in vitro and is associated to secretion of pro-angiogenic proteins. Therefore cultured viable-PBMCs and IA-PBMCs were infused in an acute rat AMI model and demonstrated that this treatment evoked massive homing of FLK1+/c-kit+ positive EPC into infarcted myocardium within 72 h and caused a significant functional recovery within 6 weeks.
Co-culture of IA-PBMCs in immune assays resulted in reduced IL-1β and IL-6 production and attenuated allogeneic dendritic mixed lymphocyte reaction (MLR). Both immune parameters were described to have a role in inflammation after myocardial ischemia. In addition, it was evidenced that viable- and IA-PBMCs secrete CXCL8/IL-8 and MMP9 into the culture medium within 24 h. These proteins were described to be responsible for neo-angiogenesis and recruitment of EPC from the BM to the ischemic myocardium. The CXCL8/IL-8 chemokine belongs to the CXCL family that consists of small (<10 kDa) heparin-binding polypeptides that bind to and have potent chemotactic activity for endothelial cells. Three amino acid residues at the N-terminus (Glu-Leu-Arg, the ELR motif) determine binding of CXC chemokines such as IL-8 and Gro-alpha to CXC receptors 1 and 2 on endothelial cells and are promoting endothelial chemotaxis and angiogenesis. In addition MMP9 secretion was identified to be pivotal in EPC mobilization since this matrixproteinase serves as signal to release soluble kit-ligand (sKitL), a chemokine that causes the transition of endothelial and hematopoietic stem cells (EPC) from the quiescent to proliferative niche in the BM. In a further in vitro assay it could be demonstrated that the supernatant (SN) derived from cultured viable- and IA-PBMCs had the ability to enhance mRNA transcription of CXCL8/IL-8 and MMP9 in mesenchymal fibroblasts. These data indicate that SN derived from viable and irradiated PBMCs contain paracrine factors that confer a biological situation in the BM which results in elution of c-kit+ EPC into circulation.
In order to prove any beneficial effect of this culture-cell suspension in vivo a model of open chest myocardial injury and infused cultured viable- and IA-PBMCs shortly after LAD ligation in rat animal model was utilized. In a first attempt it was proved that CSFE labelled IA-PBMCs were trapped in majority in the spleen and the liver. These data indicate that “cell-based therapy” does not home in infarcted myocardium. In contrary, it is much more likely that paracrine effects, either by “modified” culture medium alone or by evoked “immune mediated cytokine storm” due to cell-culture suspension exposure is causative for the regenerative effect in AMI. Since immediate inflammation after acute ischemia determines the road map to ventricular dilatation histological analysis after 72 h after AMI was performed. It could be shown that IA-PBMCs treated rats evidenced massive homing of CD68+ and VEGFa/FLK1/c-kit+ positive EPC cell populations within this time period. In contrast, more S100 β positive dendritic cells were found in control AMI, indicating enhanced APC based inflammation in control AMI.
The results seen in IA-PBMCs treated rats partly foil currently accepted knowledge about the natural course of myocardial infarction. In regards to inflammation: Under normal conditions remodeling processes are mediated by cytokines and inflammatory cells in the infarcted myocardium that initiate a wound reparation process that is landmarked by phagocytosis and resorption of the necrotic tissue, hypertrophy of surviving myocytes, angiogenesis and, to a limited extent, progenitor cell proliferation. Any experimental approach so far that intervened into inflammatory response post infarction was shown to be detrimental in AMI models. When interpreting the present histological short term data it is argued that IA-PBMC cell-medium suspension in AMI results in an advanced transitioning from inflammation to c-kit+ EPC repair phase. Previous work has confirmed that bone marrow of circulating progenitor cell therapy after AMI improve cardiac function, regardless of whether transdifferentiation of the cells to cardiomyocytes occurs or does not. In regard to c-kit+ EPC the bone marrow derived cells are considered as having a significant role as indispensable for cardiac repair. Pharmacological inhibition with imatinib mesylate and non-mobilization of c-kit+ EPC resulted in an attenuated myofibroblast response after AMI with precipitous decline in cardiac function.
These results show the regenerative potency of infusing “syngeneic” cultured IA-PBMCs in patients suffering from AMI and indicate that patients who suffer from acute AMI would benefit from being transfused with autologous (=from the patient to be treated or from the same species) IA-PBMC.
Activated peripheral blood mononuclear cells (PBMCs) and their supernatants (SN) are supposed to be beneficial in wound regeneration (Holzinger C et al. Eur J Vasc Surg. 1994 May; 8(3): 351-6.). In example 1 it could be shown that non-activated PBMCs and SN derived thereof has beneficial effects in an experimental acute myocardial infarct (AMI) and wounding model. Since non-activation of PBMCs has to be verified experimentally it was investigated whether cultivation of PBMCs led to enhanced T-cell activation markers (CD69, CD25) or enhanced inflammatory cytokine secretion (monocyte activation=TNFα, T-cell activation=INF-γ). In a control experiment cultured T cells were triggered by CD3 mAb stimulation or Phytohemagglutinin (PHA).
Venous blood was collected in EDTA-tubes from healthy volunteers. After Ficoll-Hypaque density grade separation, PBMCs were collected and divided into viable and irradiated apoptotic cells (IA-PBMC). To obtain apoptotic cells, PBMCs were irradiated with 60 Gy (Caesium-137). For flow cytometric analysis 500,000 PBMCs were cultivated in 200 μl serum-free medium. Cells were either stimulated with PHA (7 μg/mL) or CD3-mAb (10 μg/mL) or were left unstimulated. After 24 h of incubation cells were washed, stained for CD3, CD69 and CD25 (R&D System) and evaluated for surface activation markers on a FC500 (Coulter). For ELISA assays, PBMCs were cultivated overnight at a density of 2.5×106 cells/mL, either with or without PHA or CD3 stimulation. After 24 h supernatants were harvested and frozen at −20° C. Commercially available ELISA kits for TNF-α (R&D) and INF-γ (Bender) were purchased. In short, MaxiSorp plates were coated with antibodies against INF-α and INF-γ and stored overnight. After 24 h, plates were washed and samples added in duplicates to each well. After incubation and addition of a detection antibody and Streptavidin-HRP, TMB-substrate was added to each well. After color development, the enzymatic reaction was stopped by addition of sulfuric acid. Optical density values were read on a Wallac Victor3 plate reader.
FACS analysis: CD3 and PHA stimulated T cells showed an upregulation of activation markers CD69 and CD25 after 24 h of incubation. Unstimulated and apoptotic cells expressed only low amounts of CD69 and CD25 (
These data indicate that “unstimulated PBMC” evidence a distinct different phenotype (activation marker, cytokine secretion) as compared to stimulated PBMCs (PHA and CD3 mAb).
The aim of this example is to prove that PBMCs have no proliferative activity as compared to immune assays that utilize specific (CD3), unspecific (lectin, PHA) and allogeneic T-cell triggering (mixed lymphocyte reaction, MLR) in a 2 day (CD3, PHA) and 5 day (MLR) stimulation assay.
PBMCs were separated from young healthy volunteers by Ficoll density gradient centrifugation and resuspended in RPMI (Gibco, USA) containing 0.2% gentamycinsulfate (Sigma Chemical Co, USA), 1% L-Glutamin (Sigma, USA) at 1×105 cells per 200 μL. Responder cells were either stimulated by MoAb to CD3 (10 μg/mL, BD, NJ, USA), PHA (7 μL/mL, Sigma Chemical Co, USA) or with irradiated allogeneic PBMCs at a 1:1 ratio (for MLR). Plates were incubated for 48 h or 5 days and then pulsed for 18 h with 3[H]-thymidine (3.7×104 Bq/well; Amersham Pharmacia Biotech, Sweden). Cells were harvested and 3[H]-thymidine incorporation was measured in a liquid scintillation counter.
Stimulated PBMCs showed high proliferation rates as measured by 3[H]-thymidine incorporation when compared to viable PBMCs cultured in RPMI without stimulation (
This set of experiments implicates that viable PBMCs held in culture for up to 5 days did not proliferate, whereas PBMCs stimulated by different ways showed a marked proliferative response. It is concluded that culture of PBMCs without stimulation does not lead to proliferative response.
Since neo-angionesis and inflammation are strongly linked in vivo it was investigated whether these secretoma of PBMCs also exhibit anti-proliferative effects on T cells and therefore interfere with an inflammatory immune response.
Secretoma were obtained by incubating PBMCs (2.5×106/mL) from young healthy volunteers separated by Ficoll density gradient centrifugation for 24 h in RPMI (Gibco, Calif., USA) containing 0.2% gentamycinsulfate (Sigma Chemical Co, USA), 1% L-Glutamine (Sigma, USA). Supernatants were separated from the cellular fraction and stored at −80° C. For proliferation assays allogeneic PBMCs were resuspended at 1×105 cells per 200 μL RPMI after separation. Responder cells were either stimulated by MoAb to CD3 (10 μg/mL, BD, USA) or PHA (7 μL/mL, Sigma Chemical Co, USA). Different dilutions of supernatants were added. Plates were incubated for 48 h and then pulsed for 18 h with 3[H]-thymidine (3.7×104 Bq/well; Amersham Pharmacia Biotech, Sweden). Cells were harvested and 3[H]-thymidine incorporation was measured in a liquid scintillation counter.
Secretoma of allogeneic PBMCs evidenced a significant reduction of proliferation rates measured by 3[H]-thymidine incorporation when compared to positive controls (
This set of experiments implicates that secretoma obtained from viable PBMCs held in culture for 24 h exhibit significant anti-proliferative effects in vitro. These data indicate that supernatant derived from PBMCs or in lyophilized form may serve as potential therapeutic formula to treat human diseases that are related to hypoxia induced inflammation or other hyperinflammatory diseases (e.g. auto-immune diseases, inflammatory skin diseases).
In example 1 it was shown that transfusion of cultured irradiated apoptotic cells derived from peripheral blood significantly improved functional cardiac recovery after experimental myocardial infarction in rats. This improvement was based on immunosuppressive features of apoptotic cells, pro-angiogenic effects and induction of augmented homing of c-kit+ endothelial progenitor cells (EPCs).
In the present example peripheral blood mononuclear cells (PBMC) either viable or irradiated with a dose of 60 Gray were incubated for 24 hours to generate conditioned cell culture supernatants. Supernatants were lyophilized and kept frozen until use in in vivo experiments. Myocardial infarction was induced in Sprague-Dawley rats by ligating the left anterior descending artery. After the onset of ischemia, lyophilized supernatants were resuspended and injected intravenously. Tissue samples for histological and immunohistological evaluations were obtained three days and six weeks after myocardial infarction. Cardiac function was assessed by echocardiography six weeks post AMI. Sham operated and untreated animals served as controls.
Rats that were infused with supernatants obtained from apoptotic PBMCs evidenced increased myocardial angiogenesis and enhanced homing of endothelial progenitor cells within 72 hours as compared to controls. Planimetric evaluation of fibrotic areas indicated reduced infarction size in animals treated with supernatants from apoptotic cells. Furthermore, echocardiography showed a significant improvement regarding post AMI remodeling as evidenced by an attenuated loss of ejection fraction and preserved ventricular geometry. Left ventricular ejection fraction (LVEF) in rats receiving supernatants from apoptotic cells evidenced a mean value of 56±4% compared to 60±5% in sham operated animals, whereas untreated or viable cell supernatant infused animals showed a significant decline of LVEF to 44±3% and 41±4% respectively (p<0.001).
These data indicate that infusion of supernatants derived from irradiated apoptotic PBMCs in experimental AMI circumvented inflammation and caused preferential homing of regenerative EPC leading to preservation of ventricular function.
Human peripheral blood mononuclear cells (PBMC) were obtained by Ficoll density grade centrifugation as described previously. To induce apoptosis in human PBMC, cells were irradiated with 60 Gy (irradiation automat for human blood products, Department of Hematology, General Hospital Vienna). Both viable and irradiated apoptotic (IA-) PBMCs were incubated at 37° Celsius for 24 hours at various cell densities (1×106, 5×106, 10×106 and 25×106 cells/milliliter, n=5). Then supernatants were obtained and levels of secreted proteins were measured by Enzyme-linked immunosorbent assay (ELISA, R&D Systems, Minneapolis, USA), according to the protocols supplied by the manufacturer.
Syngeneic rat PBMCs for in vivo experiments were separated by density gradient centrifugation from whole-blood obtained from prior heparinized rats by puncturing of right atrium. Apoptosis was induced by Cs-137 cesium irradiation with 45 Gy for in vivo experiments and cultured at 37° Celsius at a cell density of 25×106 cells/milliliter). Induction of apoptosis by irradiation was measured by flow cytometry (annexin V staining >80% for IA-PBMC, annexin V staining <20% for viable PBMC). Cells were incubated for 24 hrs in a humidified atmosphere (5% CO2, 37° C., relative humidity 95%). Supernatants were removed and dialyzed with a 3.5 kDa cutoff (Spectrum laboratories, Breda, The Netherlands) against 50 mM ammonium acetate overnight at 4° C. Then supernatants were sterile filtrated and lyophilized. Lyophilized secretoma were stored at −80° C. and freshly resuspended for every experiment. Secretoma were random sampled for their pH value. The lyophilized powder was stored at −80° Celsius until further experiments were conducted.
Animal experiments were approved by the committee for animal research, Medical University of Vienna. All experiments were performed in accordance to the Guide for the Care and Use of Laboratory Animals by the National Institutes of Health (NTH). Myocardial infarction was induced in adult male Sprague-Dawley rats by ligating the left anterior descending artery (LAD). In short, animals were anesthetized intraperitoneally with a mixture of xylazin (1 mg/100 g bodyweight) and ketamin (10 mg/100 g bodyweight) and ventilated mechanically. A left lateral thoracotomy was performed and a ligature using 6-0 prolene was placed around the LAD beneath the left atrium. Immediately after the onset of ischemia, lyophilized supernatants obtained from 8×106 apoptotic PBMCs resuspended in 0.3 mL cell culture medium were infused over the femoral vein. Infusion of cell culture medium alone, viable PBMC supernatants and sham operation served as negative controls in this experimental setting, respectively. The experimental design is shown in
See example 1.
See example 1.
See example 1.
Statistical analysis was performed using Graph Pad Prism software (USA). All data are given as mean±standard error of the mean. Paired two-sided t-tests for dependent, unpaired t-tests for independent variables were utilized calculating significances.
Between-group differences regarding survival of acute myocardial infarction were compared by Kaplan-Meier actuarial analysis. Bonferroni-Holm correction was used to adjust p-values for multiple testing. P-values <0.05 were considered statistically significant.
The results are shown in
In Example 1, anti-inflammatory effects of PBMC secretoma in an acute myocardial infarction (AMI) animal model are evidenced. In this example it is shown that the application of PBMC secretoma after AMI induction inhibits the inflammatory damage of the heart muscle by massively down-regulating the immune response.
Based on these findings possible immunosuppressive effects of secretoma in in vitro experiments were investigated. CD4+ cells play a key role in the orchestration of the immune response as they are pivotal for the assistance of other leukocytes (e.g. macrophages, B cells, cytotoxic T cells) in immunological processes.
PBMCs from healthy volunteers were separated by Ficoll density centrifugation. Cells were resuspended in Ultra Culture Medium (Lonza, Basel, Switzerland) at a concentration of 1×106 cells/mL (sup liv). For the production of secretoma from apoptotic PBMCs was induced by irradiation with 60 Gy (sup APA). Cells were incubated for 24 h in a humidified atmosphere (5% CO2, 37° C., relative humidity 95%). Supernatants were removed and dialyzed with a 3.5 kDa cutoff (Spectrum laboratories, Breda, The Netherlands) against 50 mM ammonium acetate overnight at 4° C. Then supernatants were sterile filtrated and lyophilized. Lyophilized secretoma were stored at −80° C. and freshly resuspended for every experiment. Secretoma were random sampled for their pH value.
CD4+ cells were separated by depletion of non-CD4+ T cells utilizing a MACS bead system (Miltenyi, Bergisch Gladbach, Germany). Cells were freshly prepared and immediately used for each experiment.
Apoptosis was detected by flow cytometry using a commercially available Annexin V/PI kit (BD, New Jersey, USA). Apoptosis were defined by Annexin positive staining, late apoptosis by PI positivity.
PBMCs or purified CD4+ cells were diluted in Ultra Culture supplemented with 0.2% gentamycinsulfate (Sigma, St. Louis, Mo., USA), 0.5% β-mercapto-ethanol (Sigma, St Louis, Mo., USA) and 1% GlutaMAX-I (Invitrogen, Carlsbad, Calif., USA) to a concentration of 1×105/well in a 96 round-bottom well plate. Cells were stimulated with either PHA (7 μg/mL, Sigma, USA), CD3 (10 μg/mL, BD, New Jersey, USA) IL-2 (10 U/mL, BD, USA) or a 1:1 ratio of allogeneic irradiated (60 Gy) PBMCs for MLR. Cells were incubated for 48 h or 5 days (MLR) with different concentrations of PBMC secretoma, IL-10 or TGF-β. Then cells were pulsed for 18 h with 3[H]-thymidine (3.7×104 Bq/well; Amersham Pharmacia Biotech, Uppsala, Sweden). Cells were harvested and 3[H]-thymidine incorporation was measured in a liquid scintillation counter.
Purified CD4+ cells were stimulated with anti-CD3 (10 μg/mL) and co-incubated with different concentration of PBMC secretoma. Cells were stained for CD69 and CD25 following a standard flow cytometric staining protocol and analyzed on a flow cytometer FC500 (Beckman Coulter, Fullerton, Calif., USA).
In preliminary experiments the anti-proliferative properties of PBMC supernatants from viable cells (sup liv) were tested. In anti-CD3 and PHA stimulation experiments proliferations rates were significantly reduced by the addition of secretoma (n=10).
Based on these findings the effect of PBMC secretoma on the T-helper cell compartment was evaluated, since these cells play a pivotal role in launching and perpetuating an immune response. In analogy to
The next step was to determine possible effects of the secretoma on cell viability. Therefore, resting CD4+ cells were incubated with supernatant and Annexin V and PI positivity was evaluated. Supernatants from both, living and apoptotic PBMC, evidenced remarkable pro-apoptotic effects (
To test if PBMC secretoma were able to inhibit CD4+ cell activation the T cell activation markers CD25 and CD69 following anti-CD3 stimulation of CD4+ cells was evaluated. The upregulation of both markers was significantly and dose-dependent inhibited by PBMC secretoma (
In a last set of experiments the effect of the immune-suppressive cytokines IL-10 and TGF-β by the addition of neutralizing antibodies in these experiments was examined. Neither IL-10 and TGF-β was found to be responsible for the anti-proliferative effects of our PBMC secretoma, since demonetizing these cytokines did not increase proliferation rates (
These experiments evidence for the first time that PBMC secretoma posses immune-suppressive features in vitro. It was shown that supernatant a) reduces proliferation rates in anti-CD3, PHA and MLR stimulation experiments, b) has the potency to induce apoptosis and inhibits activation of CD4+ cells upon T cell triggering.
| Number | Date | Country | Kind |
|---|---|---|---|
| 08450199.8 | Dec 2008 | EP | regional |
This application is a continuation of U.S. patent application Ser. No. 13/140,120 filed Jun. 16, 2011, now U.S. Pat. No. 10,478,456, which is a national phase application of PCT/EP2009/067536, filed Dec. 18, 2009, which claims priority to European Patent Application No. 08450199.8 filed Dec. 18, 2008, the disclosures of which are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13140120 | Jun 2011 | US |
| Child | 16687115 | US |
