Patent Application
20110171193
The present invention relates to the use of therapeutic agents that target the molecular mechanisms of pulmonary hypertension.
Pulmonary hypertension (PH) is generally characterized by progressive increases in pulmonary vascular resistance (PVR) leading to right ventricular failure, and ultimately to death within 2-3 years after diagnosis. PH has different etiologies that share several pathological defects of the pulmonary microvasculature: worsening vasoconstriction, remodeling of pulmonary vessels, and thrombosis. These changes increase medial thickness, occlude small pulmonary arteries, and result in formation of plexiform lesions, which contribute to increased PVR.
Early assessment of PH may present the best opportunity for treatment intervention. With a better understanding of the molecular mechanisms underlying PH, it becomes possible to identify agents that may be used to treat and/or diagnose PH. There remains a need to identify one or more molecular components that have a causal connection to PH, and therapeutic agents that inhibit, decrease, enhance, or activate those molecular components in PH patients. The molecular components may represent known or unknown proteins or nucleic acids, which may be useful in diagnosing PH, and whose activities or products may be targeted for early intervention therapy.
Provided herein is a method for treating a subject having pulmonary hypertension (PH). PH may be pulmonary arterial hypertension or idiopathic pulmonary arterial hypertension. The pulmonary hypertension may be secondary to another disease, such as pulmonary fibrosis or scleroderma. An agent, such as a PKG-effector agent, may be administered to the subject. The PKG-effector agent may be a peroxynitrate scavenger, superoxide scavenger, flavonoid, NOS inhibitor, protein kinase G activator, protein kinase G enhancer, a NADPH oxidase inhibitor, a superoxide dismutase activator, a peroxidase activator, a catalase activator, an antioxidant, and/or combinations thereof. The peroxynitrate scavenger may be uric acid, a plant extracted proanthocyanidin, ascorbate, trolox, glutathione (GSH), Mn (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP), flavonoid, ebselen, catchol (1,2-dihydroxybenzene), kaempferol, galangin, caffeic acid, o-coumaric acid, p-coumaric acid, gallic acid, and ferulic acid. The proanthocyanidin may be extracted from an arborescent and/or herbaceous plant species. The superoxide scavenger may be manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP), 1-oxyl-2,2,6,6-tetramethyl-4-hydroxypiperidine (TEMPOL), NAD(P)H:quinone oxidoreductase 1, or any combination thereof. The flavonoid may be quercetin, rutin, morin, acacetin, hispidulin, hesperidin, naringin, or any combination thereof. The NOS inhibitor may be N omega-nitro-L-arginine, N omega-monomethyl-L-arginine, 1-NG monomethyl arginine (1-NMMA), a caveolin-1 peptide, ARL 17477, KLYP956, or any combination thereof. The caveolin-1 peptide may have the sequence DGIWKASFTTFTVTKYWFYR (SEQ ID NO:1). The PKG activator or enhancer may be phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P3), cyclic guanosine 3′, 5′-monophosphate (cGMP), 8-pCPT-cGMP (cGMP derivative), cGMP phosphodiesterase inhibitor, or any combination thereof. The cGMP phosphodiesterase inhibitor may be sulindac sulfone, sildenafil, tadalafil, and/or OSI-461. The superoxide dismutase activator may be a lipid peroxide, a reduced glutathione, and/or a 17β-estradiol. The NADPH oxidase inhibitor may be apocynin and/or diphenylene iodonium. The peroxidase activator may be iron, copper, melatonin, N-acetylcysteine (NAC), and/or 4-hydrobenzoic acid. The catalase activator may be an oxidized linoliec acid such as one or more of 13-hydroperoxy-9,11-octadecadienoic acid (13-HPODE), 13-hydroxy-9,11-octadecadienoic acid (13-HODE), hydrogen peroxide, and oxidized LDL.
One may administer a phosphodiesterase type-5 inhibitor (PDE5 inhibitor) before, after, or at the same time as administering the PKG-effector agent to the subject in need thereof. The PDE5 inhibitor may be sildenafil, avanafil, tadalafil, acetildenafil, CGMP specific phosphodiesterase type-5, udenafil, vardenafil, or any combination thereof.
One may administer an endothelin receptor antagonist before, after, or at the same time as administering the PKG-effector agent to the subject in need thereof. The endothelin receptor antagonist may be atrasentan, bosentan, sitaxsentan, ambrisenten, or any combination thereof.
Any agent, activator, inhibitor, or compound described herein may be administered systemically, orally, by inhalation, parenteral, nasally, vaginally, rectally, sublingually, topically, or any combination thereof. The agent, activator, inhibitor, or compound may be formulated as a capsule, tablet, an elixir, a suspension, a dry powder, an aerosol, a syrup, or any combination thereof.
Also provided herein is a method of diagnosing pulmonary hypertension in a subject. A subject having PH may have a PH marker, such as nitrated PKG. One or more antibodies may be provided that bind to nitrated PKG. The one or more antibodies may then be contacted with a sample from the subject, wherein the subject as having pulmonary hypertension if the one or more antibodies bind to nitrated PDG and is/are detected in the sample. The nitrated PKG may be detected using an antibody capable of binding the one or more antibodies that are bound to nitrated PKG.
Also provided herein is a kit, which may be used for diagnosing, monitoring, or treating PH. The kit may have a sample collecting means, a means for determining the presence or absence of a PH-marker, a PH-marker for use as a positive control, and/or a PH-marker detection means. The detection means may include substrates, such as filter paper, and protein purification reagents. The marker detection means may include primary and secondary antibodies and one or more buffers. The kit may also comprise a control sample. The control sample may not comprise a PH-marker.
The inventors have made the surprising discovery that there is an association between the molecular mechanisms derived from endothelial nitric oxide synthase (eNOS) and protein kinase G (PKG) activities, and pulmonary hypertension. eNOS and PKG have been identified as critical components in a system that regulates pulmonary vascular function. eNOS may regulate basal pulmonary vasomotor tone and its activity may be controlled by fatty acid modification, phosphorylation, as well as interaction with effector molecules. Caveolin-1 (Cav1) binding to eNOS may negatively regulate eNOS activity. Subjects having PH may have decreased expression of Cav1 in their lungs and/or endothelial cells. Subjects having PH may have enhanced or chronically active eNOS. eNOS activation may result in increased nitrative stress and/or oxidative stress. Nitrative and/or oxidative stress may result in tyrosine nitration of PKG. Tyrosine nitration of PKG may result in impaired PKG activity in lung vascular smooth muscle cells. Impaired PKG activity may result in one or more of vasoconstriction, pulmonary vascular change, and PH.
An agent that reduces or inhibits eNOS and/or nitrative stress-induced modification of PKG, therefore, may be useful for treating pulmonary hypertension. In addition, early detection of a PH-marker, such as PKG nitration, may allow treatment of the subject thereby delaying or preventing PH.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the specification and the appended claims, the singular forms “a,” “and” and “the” include plural references unless the context clearly dictates otherwise.
For the recitation of numeric ranges herein, each intervening number there between with the same degree of precision is explicitly contemplated. For example, for the range of 6-9, the numbers 7 and 8 are contemplated in addition to 6 and 9, and for the range 6.0-7.0, the number 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6,9, and 7.0 are explicitly contemplated.
a. Fragment
“Fragment” as used herein may mean a portion of a reference peptide or polypeptide or nucleic acid sequence.
b. Identical
“Identical” or “identity” as used herein in the context of two or more polypeptide or nucleotide sequences, may mean that the sequences have a specified percentage of residues or nucleotides that are the same over a specified region. The percentage may be calculated by optimally aligning the two sequences, comparing the two sequences over the specified region, determining the number of positions at which the identical residue occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the specified region, and multiplying the result by 100 to yield the percentage of sequence identity. In cases where the two sequences are of different lengths or the alignment produces one or more staggered ends and the specified region of comparison includes only a single sequence, the residues of single sequence are included in the denominator but not the numerator of the calculation.
c. Label
“Label” or “detectable label” as used herein may mean a moiety capable of generating a signal that allows the direct or indirect quantitative or relative measurement of a molecule to which it is attached. The label may be a solid such as a microtiter plate, particle, microparticle, or microscope slide; an enzyme; an enzyme substrate; an enzyme inhibitor; coenzyme; enzyme precursor; apoenzyme; fluorescent substance; pigment; chemiluminescent compound; luminescent substance; coloring substance; magnetic substance; or a metal particle such as gold colloid; a radioactive substance such as 125I, 131I, 32P, 3H, 35S, or 14C; a phosphorylated phenol derivative such as a nitrophenyl phosphate, luciferin derivative, or dioxetane derivative; or the like. The enzyme may be a dehydrogenase; an oxidoreductase such as a reductase or oxidase; a transferase that catalyzes the transfer of functional groups, such as an amino; carboxyl, methyl, acyl, or phosphate group; a hydrolase that may hydrolyzes a bond such as ester, glycoside, ether, or peptide bond; a lyases; an isomerase; or a ligase. The enzyme may also be conjugated to another enzyme.
The enzyme may be detected by enzymatic cycling. For example, when the detectable label is an alkaline phosphatase, a measurement may be made by observing the fluorescence or luminescence generated from a suitable substrate, such as an umbelliferone derivative. The umbelliferone derivative may comprise 4-methyl-umbellipheryl phosphate.
The fluorescent or chemiluminescent label may be a fluorescein isothiocyanate; a rhodamine derivative such as rhodamine β isothiocyanate or tetramethyl rhodamine isothiocyanate; a dancyl chloride (5-(dimethylamino)-1-naphtalenesulfonyl chloride); a dancyl fluoride; a fluorescamine (4-phenylspiro[furan-2(3H); 1ÿ-(3ÿH)-isobenzofuran]-3; 3ÿ-dione); a phycobiliprotein such as a phycocyanine or physoerythrin; an acridinium salt; a luminol compound such as lumiferin, luciferase, or aequorin; imidazoles; an oxalic acid ester; a chelate compound of rare earth elements such as europium (Eu), terbium (Tb) or samarium (Sm); or a coumarin derivative such as 7-amino-4-methylcoumarin.
The label may also be a hapten, such as adamantine, fluoroscein isothiocyanate, or carbazole. The hapten may allow the formation of an aggregate when contacted with a multi-valent antibody or (strep) avidin containing moiety. The hapten may also allow easy attachment of a molecule to which it is attached to a solid substrate.
The label may be detected by quantifying the level of a molecule attached to a detectable label, such as by use of electrodes; spectrophotometric measurement of color, light, or absorbance; or visual inspection.
d. Substantially Identical
“Substantially identical,” as used herein may mean that a first and second protein or nucleotide sequence are at least 50%-99% identical over a region of 8-100 or more amino acids nucleotides.
e. Therapeutically Effective Amount
“Therapeutically effective amount” as used herein may mean the amount of the subject agent or compound that will elicit the biological or medical response of a tissue, system, or subject that is being sought by the researcher, veterinarian, medical doctor or other clinician, and includes that amount of an agent or compound that, when administered, is sufficient to prevent development of, or alleviate to some extent, one or more of the symptoms of the condition or disorder being treated.
Provided herein is a method of treating a subject diagnosed with PH or having a predisposition for PH. The subject may have a PH-marker. The method may comprise administering a PKG-effector agent to the subject. The PH may be a primary disease or a secondary disease. The PH may be pulmonary arterial hypertension or idiopathic pulmonary arterial hypertension. The PH may be secondary to an interstitial lung disease. The interstitial lung disease may be pulmonary fibrosis and/or scleroderma.
In any patient that carries a PH-marker, an assessment may be made as to whether the subject is an early disease subject, wherein PH has not occurred, or whether the subject has an increase in vasoconstriction, plexiform lesions, and/or thrombosis, for example. The assessment may indicate an appropriate course of preventative or maintenance treatment. The treatment therapy may be administered in different clinical settings during the life of a PH subject: (1) during early PH disease a subject may receive one or more PKG-effector agents to delay onset of one or more characteristics associated with PH, such as vasoconstriction, plexiform lesions, and/or thrombosis; (2) after a subject has been diagnosed as having one or more PH characteristics, one or more PKG-effector agents may be administered to slow any decline in pulmonary function and reduce frequency and morbidity of pulmonary exacerbations; and/or (3) during periodic exacerbations in pulmonary symptoms, PKG-effector agent regimens may be administered to relieve symptomotology and restore pulmonary function to baseline values.
Provided herein is a method of preventing or delaying onset of PH. An agent may be administered as part of a combination treatment with one or more other compounds. The subject may be undergoing treatment for another disease. The PH may be secondary to the other disease.
The treatment of a subject with an agent may be monitored by determining protein, mRNA, and/or transcriptional level of a gene. The gene may be a NOS gene. The NOS gene may be eNOS. The treatment of a subject with an agent may be monitored by determining the level of PKG nitration.
Depending on the level of protein, mRNA, transcriptional level of a gene, or level of PKG-nitration detected, the therapeutic regimen may be maintained or adjusted. The effectiveness of treating a subject with a PKG-effector agent may comprise (1) obtaining a preadministration sample from a subject prior to administration of the agent; (2) detecting the level or amount of a protein, RNA or DNA in the preadministration sample; (3) obtaining one or more post-administration samples from the subject; (4) detecting the level of expression or activity of the protein, RNA or DNA in the postadministration sample; (5) comparing the level of expression or activity of the protein, RNA or DNA in the preadministration sample with the corresponding protein, RNA, or DNA in the postadministration sample, respectively; and (6) altering the administration of the agent to the subject accordingly.
Cells of a subject may be obtained before and after administration of a therapeutic to detect the level of expression of genes other than the gene of interest to verify that the therapeutic does not increase or decrease the expression of genes that could be deleterious. Verification may be accomplished by transcriptional profiling. mRNA from cells exposed in vivo to a therapeutic and mRNA from the same type of cells that were not exposed to the agent may be reverse transcribed and hybridized to a chip containing DNA from many genes. The expression of genes in the treated cells may be compared against cells not treated with the agent.
Appropriate PKG-effector therapy may be essential steps in the management of PH. PH-effector agent selection for any given subject in any given setting may be based on periodic isolation and identification of PH-markers from samples from a subject.
a. Subject
The subject may be a human. The subject may be diagnosed with PH or have a predisposition for PH. The subject having PH or predisposed to PH may have a PH-marker. The pulmonary hypertension may result from nitration of one or more tyrosine residues of PKG. The nitration of PKG may result from an increase in nitrative and/or oxidative stress in the system in which PKG is present. The nitrative and/or oxidative stress may result from chronically active eNOS.
b. PKG-Effector Agent
The PKG-effector agent may be any compound that directly or indirectly decreases or inhibits tyrosine nitration of PKG, or enhances or increases PKG activity. The agent may decrease nitrative or oxidative stress in a cell. The agent may block preoxynitrate formation, thereby inhibiting tyrosine nitration of PKG. The agent may block formed preoxynitrate from nitrating PKG.
PKG may be PKG type I (PKG1) or type II (PKG2). The PKG may be mammalian. PKG may be nitrated at tyrosine residue 549 and/or tyrosine residue 345 and/or tyrosine residue 124 of full length PKG1 and/or PKG2.
The PKG-effector agent may be a peroxynitrate scavenger, a superoxide scavenger, a flavonoid, a NOS inhibitor, a PKG activator or enhancer, a NADPH oxidase inhibitor, a superoxide dismutase activator, a peroxidase activator, a catalase activator, an antioxidant, or combinations thereof.
(1) Peroxynitrate Scavenger
The peroxynitrate scavenger may be any compound that reacts directly with peroxynitrite anion or peroxynitrous acid to increase the rate of peroxynitrite decomposition in proportion to their concentration. The peroxynitrite may be any compound that scavenges secondary reactive species produced from reactions with peroxynitrite or peroxynitrous acid, thereby reducing reactive radical intermediates.
The peroxynitrate scavenger may be uric acid, a plant extracted proanthocyanidin, ascorbate, trolox, glutathione (GSH), Mn (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP), flavonoid, ebselen, catchol (1,2-dihydroxybenzene), kaempferol, galangin, caffeic acid, o-coumaric acid, p-coumaric acid, gallic acid, and ferulic acid. The proanthocynidin may be extracted from an arborescent or herbaceous plant species.
(2) Superoxide Scavenger
The superoxide scavenger may be any compound or molecule that scavenges superoxide based on the reaction:
2O2−+2H+→H2O2+O2
The superoxide scavenger may be one or more of manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP), 1-oxyl-2,2,6,6-tetramethyl-4-hydroxypiperidine (TEMPOL), and NAD(P)H:quinone oxidoreductase 1. The superoxide scavenger may be an antioxidant.
(3) Flavonoid
The flavonoid may be any plant phenolic having a flavan nucleus. The flavonoid may be found in fruits, vegetables, wines, teas and/or cocoa. The flavonoid may be one or more of quercetin, rutin, morin, acacetin, hispidulin, hesperidin, and/or naringin.
(4) NOS Inhibitor
The NOS inhibitor may be a selective, or specific, inhibitor or a non-selective inhibitor. The NOS inhibitor may be an eNOS inhibitor. The eNOS inhibitor may be selective or specific for eNOS. The eNOS inhibitor may decrease or inhibit eNOS function by interacting with eNOS protein thereby reducing production of eNOS-derived nitric oxide. The eNOS inhibitor may decrease the production of eNOS by downregulating expression of eNOS. The eNOS inhibitor may inhibit or decreasing expression of eNOS-encoded DNA or RNA.
The NOS inhibitor may be N omega-nitro-L-arginine, N omega-monomethyl-L-arginine, 1-NG monomethyl arginine (1-NMMA), ARL 17477, a caveolin-1 peptide, and KLYP956. The caveolin-1 peptide may be a mimetic. The caveolin peptide may comprise the sequence DGIWKASFTTFTVTKYWFYR (SEQ ID NO. 1). The caveolin peptide sequence may consist of SEQ ID NO:1. The caveolin peptide may be substantially identical to SEQ ID NO:1. SEQ ID NO:1 may bind to eNOS.
(5) PKG Activator or Enhancer
The PKG activator or enhancer may be any compound or protein that increases PKG activity. The activator or enhancer may directly bind to PKG. The activator or enhancer may increase expression of PKG encoded DNA or RNA.
The PKG activator or enhancer may be one or more of phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P3), cyclic guanosine 3′, 5′-monophosphate (cGMP), 8-pCPT-cGMP (cGMP derivative), and/or a cGMP phosphodiesterase inhibitor. The cGMP phosphodiesterase inhibitor may be sulindac sulfone, sildenafil, tadalafil, and/or OSI-461.
(6) NADPH Oxidase Inhibitor
The NADPH oxidase inhibitor may be any compound or protein that decreases or halts NADPH expression or activity. The inhibitor may directly bind to NADPH oxidase. The inhibitor may decrease or halt expression of NADPH oxidase encoded DNA or RNA. The NADPH oxidase inhibitor may be apocynin and/or diphenylene iodonium. The NADPH oxidase inhibitor may be an antioxidant. The NADPH oxidase inhibitor may ultimately prevent or inhibit the formation of free radicals, for example reactive O2 species, thereby making it an antioxidation component.
(7) Superoxide Dismutase Activator
The superoxide dismutase activator may be any compound or protein that that increases or enhances superoxide dismutase activity or expression. The activator may directly bind to superoxide dismutase. The activator or enhancer may increase expression of superoxide dismutase encoded DNA or RNA.
The superoxide dismutase activator may be one or more of a lipid peroxide, reduced glutathione, and/or 17β-estradiol. The activator may be an antioxidant. The superoxide dismutase activator may ultimately prevent or inhibit the formation of free radicals, for example reactive O2 species, thereby making it an antioxidation component.
(8) Peroxidase Activator
The peroxidase activator may be any compound or protein that increases or enhances peroxidase activity or expression. The activator may directly bind to peroxidase. The activator may enhance or increase expression of peroxidase encoded DNA or RNA.
The peroxidase activator may be one or more of iron, copper, melatonin, NAC, and/or 4-hydrobenzoic acid. The peroxidase activator may be an antioxidant. The peroxidase activator may ultimately prevent or inhibit the formation of free radicals, for example reactive O2 species, thereby making it an antioxidation component.
(9) Catalase Activator
The catalase activator may be any compound or protein that increases or enhances catalase activity or expression. The activator may directly bind to catalase. The activator may enhance or increase expression of catalase encoded DNA or RNA.
The catalase activator may be an oxidized linoliec acid. The oxidized linoliec acid may be one or more of 13-hydroperoxy-9,11-octadecadienoic acid (13-HPODE), 13-hydroxy-9,11-octadecadienoic acid (13-HODE), hydrogen peroxide, and oxidized low density lipoprotein (LDL). The catalase activator may be an antioxidant. The catalase activator may ultimately prevent or inhibit the formation of free radicals, for example reactive O2 species, thereby making it an antioxidation component.
c. Compound for Combination Treatment
The method of treating PH may further comprise the administration of one or more compounds that inhibit phosphodiesterase activity and/or have endothelin receptor antagonist activity. The one or more compounds may be administered to the subject before, after, or at the same time as administering the PKG-effector agent.
The compound having phosphodiesterase activity may be a phosphodiesterase type-5 (PDE5). The PDE5 may be sildenafil, avanafil, tadalafil, acetildenafil, cGMP specific phosphodiesterase type-5, udenafil, vardenafil, and any combination thereof.
The compound having endothelin receptor antagonist activity may be one or more of atrasentan, bosentan, sitaxsentan, and ambrisenten.
d. Formulations and Administration
The PKG-effector agent and/or the compound for combination treatment may be formulated for parenteral administration by injection, e.g., by bolus injection or continuous infusion. Formulations for injection may be presented in unit dosage form, e.g., in ampules or in multi-dose containers, with an added preservative. The PKG-effector agent and/or the compound for combination treatment may take such a form as a suspension, solution, or emulsion in oily or aqueous vehicles, and may contain formulating agents such as suspending, stabilizing and/or dispersing agents. PKG-effector agent and/or the compound for combination treatment preparations for oral administration may be suitably formulated to give controlled release of the PKG-effector agent and/or the compound for combination treatment. For buccal administration, the PKG-effector agent and/or the compound for combination treatment may take the form of tablets or lozenges formulated in conventional manner. For administration by inhalation, the PKG-effector agent and/or the compound for combination treatment for use according to the present invention may be delivered in the form of an aerosol spray presentation from pressurized packs or a nebuliser, with the use of a suitable propellant. In the case of a pressurized aerosol, the dosage unit may be determined by providing a valve to deliver a metered amount.
In general, the PKG-effector agent and/or the compound for combination treatment of this invention will be administered in a therapeutically effective amount by any of the accepted modes of administration for agents and compounds that serve similar utilities. The actual amount of the PKG-effector agent and/or the compound for combination treatment of this invention will depend upon numerous factors such as the severity of the disease to be treated, the age and relative health of the subject, the potency of the compound used, the route and form of administration, and other factors. The PKG-effector agent and/or the compound for combination treatment can be administered more than once a day, preferably once or twice a day. Therapeutically effective amounts of an PKG-effector agent and/or the compound for combination treatment may range from approximately 0.05 mg to 10 g per kilogram body weight of the subject per day.
The detection of a PH-marker in a sample from a subject may be indicative of the subject having PH or having a predisposition for PH. The method may detect PKG nitration in a subject's lung. The method may detect PKG nitration in a sample taken from the subject. The sample may be a biopsy. The sample or biopsy may be a lung sample or biopsy. The method may use antibodies to PKG. The PKG may be nitrated. Nitrated PKG may be nitrated PKG-1α, PKG-1β, PKG-2, or peptides thereof. The PKG or PKG peptide may be human. The nitrated PKG or PKG peptide may be nitrated at tyrosine residue 549 and/or 345 and/or 124. The nitrated residues may correspond to tyrosine 549, 345, and/or 124 of PKG-1α. The detection of a nitrated PKG in a subject sample may be compared to a control sample. The presence of nitrated PKG in a subject sample may be indicative of PH. An increased level of PKG nitration in the subject sample as compared to a normal control sample may be indicative of the subject having PH or having a predisposition for PH. The pulmonary hypertension may be idiopathic pulmonary hypertension.
a. Sample
The sample may be any cell type, tissue, or bodily fluid from the subject. Such cell types, tissues, and fluid may include sections of tissues such as biopsy and autopsy samples, frozen sections taken for histologic purposes, blood, plasma, serum, sputum, stool, tears, mucus, saliva, hair, and skin. Cell types and tissues may also include lung tissue or cells, lymph fluid, ascetic fluid, gynecological fluid, urine, peritoneal fluid, cerebrospinal fluid, a fluid collected by vaginal rinsing, or a fluid collected by vaginal flushing. A tissue or cell type may be provided by removing a sample of cells from a subject, but can also be accomplished by using previously isolated cells (e.g., isolated by another person, at another time, and/or for another purpose). Archival tissues, such as those having treatment or outcome history, may also be used.
b. PH-Marker
The PH-marker may be a protein marker. The marker may be PKG. PKG may be PKG type I (PKG1) or type II (PKG2). The PKG may be mammalian. The PKG may be nitrated at tyrosine residue 549 and/or tyrosine residue 345 and/or tyrosine residue 124 of full length PKG1 and/or PKG2.
c. Detection
The PH-marker may be detected in a sample derived from the patient. Many methods are available for detecting a marker in a subject or in a sample taken from the subject. These methods include immunological methods, which may be used to detect such proteins on whole cells. Expression of a PH-marker may be assessed by any of a wide variety of well-known methods for detecting expression of a transcribed molecule or protein. Non-limiting examples of such methods include immunological methods for detection of secreted, cell-surface, cytoplasmic, or nuclear proteins, protein purification methods, protein function or activity assays, nucleic acid hybridization methods, nucleic acid reverse transcription methods, and nucleic acid amplification methods.
In a preferred embodiment, the presence or expression of a PH-marker may be assessed using an antibody. The antibody may be labeled (e.g. a radio-labeled, chromophore-labeled, fluorophore-labeled, or enzyme-labeled antibody). The antibody may be an antibody derivative (e.g. an antibody conjugated with a substrate or with the protein or ligand of a protein-ligand pair (e.g. biotin-streptavidin)), or an antibody fragment (e.g. a single-chain antibody, an isolated antibody hypervariable domain, etc.) which binds specifically with the PH-marker.
Also provided herein is a method of monitoring a subject for PH. The subject may have been determined to have a predisposition for PH. The subject may already have a primary pulmonary disease, such as pulmonary fibrosis. It may be desirable to measure the effects of treatment on PH by treating the patient using a method comprising monitoring PKG nitration. Monitoring for PKG nitration, or progression of PKG nitration, may include any assay to detect PKG nitration.
Provided herein is a kit, which may be used for diagnosing, monitoring, or treating PH. The kit may comprise a sample collecting means. The kit may also comprise a means for determining a PH-marker, a PH-marker for use as a positive control, and/or a PH-marker detection means. The detection means may include substrates, such as filter paper, and protein purification reagents. Marker detection means may also be included in the kit. Such means may include primary and secondary antibodies and one or more buffers. The kit may also comprise a control sample. The control sample may not comprise a PH-marker.
The kit may also comprise one or more containers, such as vials or bottles, with each container containing a separate reagent. The kit may further comprise written instructions, which may describe how to perform or interpret an assay or method described herein.
The present invention has multiple aspects, illustrated by the following non-limiting examples.
Throughout the Examples, data are presented as mean±SD. Statistical significance of differences between group means was determined using an unpaired two-tailed Student's t-test; P<0.05 was considered significant.
To generate the DKO mice, eNOS−/− mice (The Jackson Laboratory) were bred into the background of Cav1−/− mice (The Jackson Laboratory) to produce Cav1+/−/eNOS+/−double heterozygote (F1). F1 pups were then mated to generate WT, Cav1−/−, eNOS−/−, and Cav1−/−/eNOS−/− (DKO) mice. All mice were bred and maintained in the University of Illinois according to NIH guidelines. Approval for animal care and use for these experiments was granted by the institutional Animal Care and Use Committee.
RNA was isolated using an RNeasy Mini kit including DNase I digestion (Qiagen) and one-step QRT-PCR analyses were performed in ABI Prism 7000 Sequence Detection System (Applied Biosystems) with QuantiTect SYBR Green RT-PCR kit (Qiagen). The following primer sets were used for analyses: mouse p21Cip1, 5′-GACAAGAGGCCCAGTACTTCCT-3′ (SEQ ID NO:2) and 5′-CAATCTGCGCTTGGAGTGATA-3′ (SEQ ID NO:3); mouse IGF-1,5′-ACAGGCTATGGCTCCAGCAT-3′ (SEQ ID NO:4) and 5′-GCTCCGGAAGCAACACTCAT-3′ (SEQ ID NO:5); and mouse VEGF-A, 5′-TCCAAGATCCGCAGACGTGTAA-3′ (SEQ ID NO:6) and 5′-TGGCTTGTCACATCTGCAAGTAC-3′ (SEQ ID NO:7). Mouse cyclophilin primer set not shown. All gene expression was normalized to cyclophilin as an internal control.
Western blot analyses were performed using anti-Cav1 (1:1000, Santa Cruz Biotechnology), anti-eNOS (1:1000, Upstate Biotechnology), and anti-PKG-I (1 mg/ml, a generous gift from Dr. X-P. Du at Department of Pharmacology, University of Illinois at Chicago). The same blots were reprobed with either anti-a-actin (1:400, Santa Cruz Biotechnology) or anti-GAPDH (1:2000, Santa Cruz Biotechnology) as a loading control. To detect PKG-I tyrosine nitration, protein lysates from either mouse lungs or primary cultures of human pulmonary artery smooth muscle cells were immunoprecipitated overnight with anti-PKG-I and then probed with anti-nitrotyrosine (1:2500, Cayman Chemical).
NO measurements were performed using a three-electrode system. Briefly, lungs were cut into 1 mm thick slices and preincubated in L-arginine-free HBSS at 370 C for 1 h. With the aid of a micromanipulator, the NO sensor was carefully placed on the surface of the lung slice and the baseline was recorded. To determine the lung eNOS activity, the samples were subsequently incubated in a bath containing HBSS, 1 mM L-arginine, 2 mM iNOS inhibitor (1400 W) for 20 min. 1 mM calcium ionophore (A23187) was added and NO release was recorded for 20 s. NO production was measured as area under the curve during the 20-min period.
RVSP was determined as follows. Briefly, following anesthesia, mice were prepared for catheterization. A 1.4 F pressure transducer catheter (Millar Instruments) was carefully inserted via the right external jugular vein into the right ventricle to obtain measurements of RVSP using the Acknowledge software (Biopac Systems, Inc.). To determine lung vascular resistance, mice were anesthetized and prepared for perfusion. Pulmonary arterial (Ppa) and venous (Pv) pressures were monitored continuously through the pulmonary arterial and left atrial cannula, which were connected to a pressure transducer. After a period of 20 min during which isogravimetric conditions were attained, the flow was stepped cumulatively from 2 to 3.5, and then to 5 mL/min. Ppa was measured at steady-state and was plotted against the flow, which was measured by weighing the effluent collected over a one-minute period. The pulmonary vascular resistance was derived as the slope of the pressure flow curve.
In vitro activity of PKG was determined by measuring the transfer of the [g-32P] phosphate group of ATP to the specific PKG substrate, BPDEtide (Calbiochem) in the absence or presence of exogenous 2.5 mM cGMP. The assay was carried out in a total volume of 50 ml containing 150 mM BPDEtide, 10 mM HEPES, 35 mM b-glycerophosphate, 4 mM magnesium acetate, 5 mM PKI (a synthetic protein kinase A inhibitor, Calbiochem), 0.5 mM EDTA, 200 mM ATP, and 2 mCi of [g-32P]ATP (specific activity 3,000 Ci/mmol, GE Amersham). The mixture was incubated at 300 C for 12 min and terminated by spotting 40 ml aliquots of mixture on phosphocellulose papers (P81, Whatman). The papers were then washed and counted in a liquid scintillation counter. PKG activity is expressed as picmoles of 32P incorporated into PKG substrate per minute per milligram protein.
Following PBS perfusion, the lung tissues were fixed for 5 min by instillation of 10% PBS-buffered formalin through trachea catheterization at a transpulmonary pressure of 15 cm H2O. After tracheal ligation, harvested lungs were fixed with 10% PBS-buffered formalin overnight at 40 C with agitation. After paraffin processing, the tissues were cut into semithin 4 to 5 mm thick, and stained with either H & E for histological analysis or an antibody against nitrotyrosine (Upstate Biotechnology) for immunohistochemistry. Immunostaining was developed with a Vectastain ABC kit (Vector Laboratories).
To generate a mouse model with genetic deletions of both Cav1 and eNOS, eNOS−/− mice 24 were mated into the background of Cav1−/− mice 25. DKO mice were born normally and were indistinguishable from wild-type (WT) littermates. We observed that 85% (n=200) of DKO mice survived as long as WT mice (up to 18 month). To eliminate any background effects from either eNOS−/− or Cav1−/− line on the observed phenotype of DKO mice, F4 or higher generations were used for these studies.
To determine physiological consequences of chronic activation of eNOS in Cav1−/− lungs, right ventricular systolic pressure (RVSP) was measured as indicative of pulmonary arterial systolic pressure.
Studies have demonstrated severe lung structural abnormalities in Cav1−/− mice such as hypercellularity and thickened alveolar septa 18,20,25. To address whether genetic ablation of eNOS prevents the lung pathology seen in Cav1−/− lungs, we processed lungs for histological studies.
As shown in
In view of the foregoing, downregulation of p21Cip1 in Cav1−/− lungs may be the result of increased expression of these growth factors in Cav1−/− lungs.
NO present in high concentration reacts with superoxide to form the damaging reactive nitrogen species peroxynitrite 27, which modifies proteins through tyrosine nitration. Using immunostaining of nitrotyrosine generated by tyrosine nitration as a measure of formation of peroxynitrite, Cav1−/− lungs demonstrated prominent nitrotyrosine immunostaining whereas DKO lungs similar to WT lungs exhibited little nitrotyrosine immunostaining (
We examined tyrosine nitration of PKG in Cav1−/− lungs since PKG is the downstream target of NO signaling and its activation regulates vasorelaxation.
In
To test the hypothesis that peroxynitrite modifies PKG through tyrosine nitration thereby impairing kinase activity, we treated subconfluent human pulmonary artery smooth muscle cells with 3-morpholinosydnonimine (SIN-1), a donor of superoxide and NO, which spontaneously forms peroxynitrite at the two concentrations used.
More specifically, in
To determine whether pharmacological inhibition of eNOS in Cav1−/− mice can reverse PH, we administered N-Nitro-L-Arginine Methyl Ester (L-NAME), a NOS inhibitor, to Cav1−/− mice following onset of PH. In this treatment protocol, 8 month old Cav1−/− mice received either L-NAME or its inactive analog D-NAME in drinking water (1 mg/ml) for 5 wk. In
More specifically, L-NAME treatment substantially reduced RVSP whereas D-NAME had no effect (
The following primer sets were used for analyses shown in
sGC Enzyme Activity and Lung cGMP Measurement. sGC enzyme activity was measured as previously described by Mittal. Briefly, lung tissue was homogenized in buffer containing 50 mM Tris.HCl (pH 7.5), 1 mM EDTA, 1 mM dithiothreitol, 2 mM phenylmethyl sulfonyl fluoride, 0.5 mM 3-isobutyl-1-methylxanthine, and protease inhibitor cocktail (Sigma-Aldrich). Extracts were centrifuged at 100,000 g for 1 h at 40 C. Supernatants (50 μg in 30 μl lysis buffer) were incubated for 10 min at 37° C. in a reaction mixture containing 50 mM Tris.HCl (pH 7.5), 5 mM MgCl2, 0.5 mM 3-isobutyl-1-methylxanthine, 7.5 mM creatine phosphate, 0.2 mg/ml creatine phosphokinase, and 1 mM GTP with (Basal) or without 1 mM sodium nitroprusside. The total reaction volume was 100 μl The reaction was terminated by 0.1 N HCl. The cGMP in the reaction mixture following dilution with assay buffer (1:5 dilutions for the basal reaction mixture and 1:50 dilution for the sodium nitroprusside-stimulated reaction mixture) was measured using a commercial cGMP enzyme immunoassay kit (GE Healthcare) following manufacture's instruction. sGC activity is expressed as picomoles of cGMP produced per min per milligram of lung extract supernatant. To determine the lung cGMP levels, mouse lung tissue was homogenized in cold 6% (w/v) trichloroacetic acid and supernatant was collected following centrifugation at 2000 g for 15 min at 4° C. Following 4 washing of the supernatant with 5 volumes of water saturated diethyl ether, the aqueous extract of cGMP was lyophilized and resuspended in 220 μl of assay buffer. cGMP levels were measured with the same cGMP enzyme immunoassay kit following manufacture's instruction. Mouse lung cGMP levels were expressed as pmoles/g wet lung.
In Vitro PKG Kinase Assay. Mouse lung tissue was homogenized in 800 μl lysis buffer containing 10 mM HEPES, 0.5 mM EDTA, 10 mM dithiothreitol, 1 mM 3-isobutyl-1-methylxanthine, 125 mM KCl, 35 mM b-glycerophosphate, 0.1 mg/ml trypsin inhibitor, 1 μM antipain, 1 μM E64, and 0.4 mM PMSF. The lysate was then sonicated for 10 s for 3 times following centrifugation at 14,000 rpm for 15 ml at 4° C. The supernatant (7.5 μg in 20 μl of lysis buffer) was used for PKG activity measurement. The assay was carried out in a total volume of 50 ml containing 150 mM BPDEtide (Calbiochem), 10 mM HEPES, 35 mM b-glycerophosphate, 4 mM magnesium acetate, 5 mM PKI (a synthetic protein kinase A inhibitor, Calbiochem), 0.5 mM EDTA, 200 mM ATP, and 2 mCi of [γ-32P]ATP (specific activity 3,000 Ci/mmol, GE Healthcare) with or without addition of 2.5 μM cGMP. The mixture was incubated at 30° C. for 12 min and terminated by spotting 40 ml aliquots of mixture on phosphocellulose papers (P81, Whatman). Following 4 washing with 75 mM of ice-cold phosphoric acid solution, the papers were then dried and counted in a liquid scintillation counter. 5 μl of the reaction mixture was directly spotted on the phosphocellulose paper without washing for determination of the γ-32P-ATP specific activity. PKG activity is expressed as picmoles of 32P incorporated into PKG substrate per min per microgram protein.
NO Measurement. eNOS-derived NO from human lung samples was also determined using the three-electrode system (1). Briefly, with the aid of a micromanipulator, the NO sensor was carefully placed on the surface of the lung slice and the baseline was recorded. To determine the lung eNOS activity, the samples were subsequently incubated in a bath containing HBSS, and iNOS and nNOS inhibitors for 20 min. After addition of 1 mM L-Arginine, NO release was recorded and the maximal current at 20 s was calculated for eNOS-derived NO production. Similarly, iNOS-derived NO was also determined with the three-electrode system. Following 20 min incubation of eNOS and nNOS inhibitor (L-NNA, 4 μM), L-Arginine was added and NO release was recorded. The maximal current at 20 min was calculated for iNOS-derived NO production.
Detection of Protein S-nitrosylation. S-nitrosylation was detected with the S-Nitrosylated Protein Detection Assay kit (Cayman Chemical) following manufacture's instruction. Briefly, freshly isolated mouse lung tissue under weak fluorescent light condition was homogenized in Buffer A containing blocking reagent and precipitated with ice-cold acetone. The precipitates were then resuspended in Buffer B containing reducing and labeling reagents and incubated for 1 h at room temperature. All these procedures were performed under weak fluorescent light condition. And then, the biotin-labeled proteins were precipitated with ice-cold acetone and resuspended in washing buffer. 10 μg of each sample was used for direct Western blotting analysis of total S-nitrosylation. The same blot was blotted with anti-GAPDH for loading control. To detect PKG-1 S-nitrosylation, the samples (300 μg each) were immunoprecipitated with anti-PKG-1 (2 μg) overnight and then detected for S-nitrosylation by Western blotting analysis. The same blot was blotted with anti-PKG-1 for detection of PKG-1 expression.
In Vivo Gene Delivery to Lungs. WT and Cav1−/− mice were randomized into two groups for AdvPKG and AdvLacZ, respectively, and anesthetized for delivery of recombinant adenovirus. While breathing spontaneously, each mouse was nebulized with 75 p. 1 of sterile PBS solution containing 1.5×108 pfu of recombinant adenovirus expressing either human PKG-1 (a generous gift from Dr. K. D. Bloch at the Cardiovascular Research Center and Department of Anesthesia, Massachusetts General Hospital) or LacZ by use of an intratracheal microspray device through the mouth (MicroSprayer, Penn-Century Inc.). 7d after nebulization, mice were anesthetized for measurements of RVSP and PVR. Lungs were collected for Western blot analysis.
Histology and Imaging. Lung tissues were fixed and processed for H & E staining and immunofluorescent staining. for 5 min by instillation of 10% PBS-buffered formalin through trachea catheterization at a transpulmonary pressure of 15 cm H2O, and then overnight at 4° C. with agitation. After paraffin processing, the tissues were cut into semi-thin 4 to 5 mm thick, and stained with H & E for histological analysis. For immunofluorescent staining, antigen retrieval was performed by incubating the slides in 10 mM sodium citrate (pH 6.0) at 95° C. for 10 min. After 1 h incubation at room temperature in a blocking solution containing 2% bovine albumin serum, 0.1% Triton X-100, and 2% normal goat serum, the sections were incubated for 2 h at room temperature with anti-smooth muscle a-actin mAb (1:400, Sigma-Aldrich) and then 1 h with FITC-conjugated goat anti-mouse IgG (1:250, Sigma-Aldrich). Nuclei were counterstained with DAPI. The anti-a-SMA-positive pulmonary arterial vessels per field (200×) were counted based on the diameter (<40 μm versus>40 μm). Twenty fields per section were randomly identified and counted. To examine tyrosine nitration in the pulmonary vasculature, cryosections of mouse lung tissues were fixed with 4% paraformaldehyde and then immunostained with anti-nitrotyrosine (mouse monoclonal antibody, 1:80, Cayman Chemical) to detect nitration (green) and anti-smooth muscle a-actin (rabbit polyclonal antibody, 1:250, Abcam) to detect muscularized vessels (red). The Nuclei were counterstained with DAPI.
Animals. To generate the DKO mice, eNOS−/− mice were bred into the background of Cav1−/− mice (The Jackson Laboratory). All mice were bred and maintained in the University of Illinois according to NIH guidelines. Approval for animal care and use for these experiments was granted by the Institutional Animal Care and Use Committee of the University of Illinois at Chicago.
Human Subjects. Human lung tissues were obtained from patients undergoing lung transplantation for IPAH (n=4; age 31.5±19.2 yr; gender, 2M+2F) and from unused donor lungs (n=4; age 36.2±16.1 yr; gender, M). Informed consent and local ethical approval from the Hammersmith Hospitals (Ref. No. 2001/6003) and Royal Brompton & Harefield Hospitals (Ref. No. 01-210) ethics committees were obtained prior to tissue collection.
Molecular Analysis. Western blot analyses were performed using anti-caveolin-1 (1:1000) and anti-iNOS (1:500, Santa Cruz Biotechnology), anti-eNOS (1:1500) and anti-hsp90 (1:1000, BD Biosciences), anti-nitrotyrosine (1:1000, Millipore), anti-PKG-1 (1 mg/ml, a generous gift from Dr. X.-P. Du at Department of Pharmacology, University of Illinois at Chicago), anti-p42/44 and anti-phosphorylated p42/44 (1:1000, Cell Signaling Technology), anti-VASP (1:1000, Axxora, LLC) and anti-VASP phosphoSer239 (1:200, Axxora, LLC). Anti-a-actin (1:4000, Sigma) or anti-GAPDH (1:2000, Santa Cruz Biotechnology) was used as a loading control. To detect PKG-1 tyrosine nitration, protein lysates from either mouse or human lungs (500 μg each) or primary cultures of human pulmonary artery smooth muscle cells (80 μg each) were immunoprecipitated overnight with anti-PKG-1 (2 μg each) and then probed with anti-nitrotyrosine (1:2500, Cayman Chemical).
RNA was isolated using an RNeasy Mini kit including DNase I digestion (Qiagen) and quantitative RT-PCR analysis was performed in ABI Prism 7000 Sequence Detection System (Applied Biosystems) with QuantiTect SYBR Green RT-PCR kit (Qiagen). The sequences of the primers were provided in Supplemental Methods.
NO Measurements. eNOS-derived NO from lung samples was determined with Griess reagent (Promega Co). Samples were incubated in 1 ml F-12 DMEM with inhibitors for iNOS (1400 W, 4 μM) and nNOS (N{acute over (ω)}-propyl-L-Arginine, 1 μM) for 20 min. 1 mM L-arginine was then added and incubated for 3 h. Aliquots of medium were collected and NO release was determined by measuring the concentration of nitrite and nitrate (NOx) in the aliquot in two steps using the Nitralyzer-II kit (World Precision Instruments, Inc) and Griess reagent. Results were expressed as nM/g lung/h incubation. Total NOx production from mouse lung samples was determined with similar method without incubation of NOS inhibitors. eNOS-derived NO from human lung samples was also determined using the three-electrode system as detailed in Supplemental Methods.
Hemodynamic Measurements. RVSP was determined with a 1.4 F pressure transducer catheter (Millar Instruments) and the Acknowledge software (Biopac Systems, Inc.). Briefly, the 1.4 F pressure transducer was inserted through the right external jugular vein of anesthetized mice (100 mg ketamine/5 mg xylazine/kg BW, i.p.) and threaded into the right ventricle. RVSP was then recorded and analyzed with the Acknowledge Software.
PVR was measured. Briefly, the isolated lungs was ventilated (120/min and end expiratory pressure of 2.0 cm H2O) and perfused at constant flow (2 ml/min), and venous pressure (+4 cm H2O) with RPMI 1640 medium supplemented with 3 g/100 ml of BSA. Pulmonary arterial and venous pressures were monitored using pressure transducers (Model P23XL-1; Grass Instrument Co.). PVR was calculated from (Ppa−Ppv)/(Q/100 g), where Ppa and Ppv are pulmonary arterial and venous pressures, and Q is flow (2 ml/min).
PKG Kinase Assay. In vitro activity of PKG was determined by measuring the transfer of the [g-32P] phosphate group of ATP to the specific PKG substrate, BPDEtide (Calbiochem) in the absence or presence of exogenous 2.5 mM cGMP as described in Example 13. PKG activity is expressed as picmoles of 32P incorporated into PKG substrate per min per microgram protein.
Identification of Nitrated Tyrosine Residues of PKG-1a. Tyrosine residue was mutated to Phenylalanine by site-directed mutagenesis following manufacture's instruction (Stratagene). Myc-tagged wild-type and mutant PKG-1a were overexpressed in human lung microvascular endothelial cells and cell lysates were then immunoprecipitated with anti-Myc for 4 hr at RT. The same amount of immunoprecipitates was incubated with either 100 μM of peroxynitrite (in 0.1N NaOH) or the same amount of 0.1N NaOH (control). Following 14 min incubation in 50 mM K2HPO4 buffer at RT, kinase activity was then measured as described above.
Histology and Imaging. Lung tissues were fixed and processed for H & E staining and immunofluorescent staining.
Statistical Analysis. Data are presented as mean±SD. Statistical significance of differences between group means was determined using an unpaired two-tailed Student's t-test; P<0.05 was considered significant.
Studies have demonstrated severe lung hypercellularity and thickening of alveolar septa in Cav1−/− mice; thus, we addressed the possibility that chronically active eNOS in Cav1−/− mice was responsible for the lung pathology in these mice. DKO lungs exhibited normal alveolar-capillary structure and vessel wall thickness in contrast to Cav1−/− lungs. Histological scoring showed normal pulmonary morphology in DKO lungs. To quantify the number of muscularized distal pulmonary arteries, an underlying feature of pulmonary vascular remodeling in PH, lung sections were stained with anti-a-SMA. Cav1−/− lungs exhibited 3-fold increase in muscularized distal arteries (<40 μm in diameter) compared to WT, whereas similar number of muscularized large vessels was seen in both Cav1−/− and WT lungs. DKO lungs exhibited similar number of muscularized distal and large vessels as the WT and eNOS−/− lungs.
To address the molecular basis of the hyperplasia and pulmonary vascular remodeling seen in Cav1−/− lungs, we examined ERK signaling and expression of genes regulating cell cycle progression.
As shown in
NO reacts with superoxide to form the damaging reactive nitrogen species peroxynitrite that modifies proteins and may interfere with their function through tyrosine nitration. Immunostaining of nitrotyrosine, a surrogate measure of peroxynitrite, showed that Cav1−/− lungs had marked nitrotyrosine compared to WT and DKO lungs, indicating the formation of peroxynitrite in Cav1−/− lungs. Prominent nitrotyrosine immunostaining was also evident in Cav1−/− pulmonary vasculature including muscularized distal arteries. Western blotting also demonstrated increased tyrosine nitration of proteins in Cav1−/− lungs whereas no difference in S-nitrosylation of proteins was seen in Cav1−/− and WT lungs.
We determined the activities of soluble guanylyl cyclase (sGC) and protein kinase G (PKG), the two major downstream targets of NO signaling, to investigate whether their functions were impaired by tyrosine nitration in Cav1−/− lungs. With respect to
For
For
To address the role of peroxynitrite in the mechanism of the observed impairment of PKG activity, we treated human pulmonary artery smooth muscle cells with 3-morpholinosydnonimine (SIN-1), the superoxide and NO donor that forms peroxynitrite simultaneously (30). SIN-1 concentrations as low as 10 mM were shown to cause marked PKG tyrosine nitration (
To identify the target tyrosine residues responsible for impairment of PKG activity upon nitration, we mutated all tyrosine residues in the catalytic domain of human PKG-1a into phenylalanine and expressed these myc-tagged PKG-1 mutants with either single or double mutations in human lung microvascular endothelial cells. As shown in
To determine whether tyrosine nitration-mediated impairment of PKG activity was responsible for the development of PH in Cav1−/− mice, we carried out a series of experiments that included blocking peroxynitrite formation and overexpressing PKG. We first determined whether scavenging superoxide by manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP, a superoxide dismutase mimetic) could reverse PH in Cav1−/− mice. In this experiment, 8 month old Cav1−/− mice received either saline or MnTMPyP (5 mg/kg, i.p. daily) for 6 wk. We observed that MnTMPyP treatment reduced RVSP (
Materials and methods for
We further tested the hypothesis that nitrative stress-induced PH in Cav1−/− mice was mediated by impaired PKG activity. Recombinant adenoviruses overexpressing human PKG-1 or LacZ were administered into lungs of 10 month old WT and Cav1−/− mice via an intra-tracheal microspray device. At 7 d post-infection, PKG-1 protein expression was elevated by 50% in AdvPKG-treated Cav1−/− lungs compared to AdvLacZ-treated control lungs (
Materials and methods for
To address the relevance of these observations in mice to the pathogenesis of IPAH in patients, we determined eNOS activity, PKG tyrosine nitration and expression of caveolin-1, eNOS, and PKG-1 in lung tissues from IPAH patients. eNOS activities were increased in IPAH lungs compared to normal lungs (
Material and methods for
While the present invention is described in connection with what is presently considered to be the most practical and preferred embodiments, it should be appreciated that the invention is not limited to the disclosed embodiments, and is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the claims. Modifications and variations in the present invention may be made without departing from the novel aspects of the invention as defined in the claims. The appended claims should be construed broadly and in a manner consistent with the spirit and the scope of the invention herein.
The present application claims the benefit of the filing dates of provisional applications 61/182,457, filed on May 29, 2009, and 61/060,831, filed Jun. 12, 2008, which are both incorporated by reference in their entirety.
This invention was made with government support under National Heart, Lung and Blood Institute grant number PO1 HL060678 and National Heart, Lung and Blood Institute grant number R01 HL085462. The government has certain rights in the invention.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US09/47241 | 6/12/2009 | WO | 00 | 12/7/2010 |
| Number | Date | Country | |
|---|---|---|---|
| 61060831 | Jun 2008 | US | |
| 61182457 | May 2009 | US |
