3-nitrotyrosine and ciglitazone

Accumulation of interstitial collagen (fibrosis) between the endothelium and myocytes is one of the hallmarks of cardiac failure in renovascular hypertension (RVH). Renal insufficiency increases plasma homocysteine (Hcy), and levels of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) are inversely related to plasma Hcy levels. We hypothesize that in RVH, accumulation of collagen between the endothelium and myocytes leads to endothelial-myocyte disconnection and uncoupling, in part, by hyperhomocysteinemia. Furthermore, we hypothesize that Hcy increases reactive oxygen species, generates nitrotyrosine, activates latent matrix metalloproteinase, and decreases the levels of endothelial nitric oxide in response to antagonizing PPAR-gamma. To create RVH in mice, the left renal artery was clipped with 0.4-mm silver wire for the 2 kidney, 1 clip (2K1C) method. Sham surgery was used as a control. To induce PPAR-gamma, 8 microg/mL ciglitazone (CZ) was administered to drinking water 2 days before surgery and continued for 4 weeks. Mice were grouped as 2K1C, sham, 2K1C+CZ, or sham+CZ (n = 6 in each group). Plasma Hcy increased 2-fold in the 2K1C-treated group (p < 0.05) as compared with the sham, and CZ had no effect on Hcy levels as compared to the 2K1C-treated group. Hcy binding in cardiac tissue homogenates decreased in the 2K1C-treated group but was substantially higher in the CZ-treated group. Cardiac reactive oxygen species levels were increased and endothelial nitric oxide were decreased in the 2K1C-treated group. Matrix metalloproteinase-2 and -9 activities were increased in the 2K1C-treated group compared with the control. Levels of cardiac inhibitor of metalloproteinase were decreased, whereas there was no change in tissue inhibitor of metalloproteinase-1 expression in the 2K1C-treated group vs. the sham-treated group. Collagen and nitrotyrosine levels were increased in the 2K1C-treated group, but mice treated with CZ showed lower levels comparatively. Cardiac transferase deoxyuridine nick-end labeling-positive cells were increased, and muscle cells were impaired in the 2K1C-treated mice vs. the sham-control mice. This was associated with decreased acetylcholine and bradykinin responses, which suggests endothelial-myocyte uncoupling in 2K1C-treated mice. Our results suggest that fibrosis between the endothelium and myocytes leads to an endothelial-myocyte disconnection and uncoupling by Hcy accumulation secondary to increased reactive oxygen s

Topics: Acetylcholine; Animals; Blotting, Western; Collagen; Endothelin-1; Endothelium, Vascular; Fibrosis; Homocysteine; Hypertension, Renovascular; Hypoglycemic Agents; Kidney; Male; Matrix Metalloproteinases; Mice; Mice, Inbred C57BL; Myocardial Contraction; Myocytes, Cardiac; Nitroprusside; PPAR gamma; Proteinuria; Thiazolidinediones; Tissue Inhibitor of Metalloproteinase-1; Tyrosine; Vasodilator Agents; Ventricular Remodeling

Peroxisome proliferator activator receptor-gamma (PPARgamma) is a nuclear receptor that controls the expression of several genes involved in metabolic homeostasis. We investigated the role of PPARgamma during the inflammatory response in sepsis by the use of the PPARgamma ligands, 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)) and ciglitazone. Polymicrobial sepsis was induced by cecal ligation and puncture in rats and was associated with hypotension, multiple organ failure, and 50% mortality. PPARgamma expression was markedly reduced in lung and thoracic aorta after sepsis. Immunohistochemistry showed positive staining for nitrotyrosine and poly(ADP-ribose) synthetase in thoracic aortas. Plasma levels of TNF-alpha, IL-6, and IL-10 were increased. Elevated activity of myeloperoxidase was found in lung, colon, and liver, indicating a massive infiltration of neutrophils. These events were preceded by degradation of inhibitor kappaBalpha (IkappaBalpha), activation of IkappaB kinase complex, and c-Jun NH(2)-terminal kinase and, subsequently, activation of NF-kappaB and AP-1 in the lung. In vivo treatment with ciglitazone or 15d-PGJ(2) ameliorated hypotension and survival, blunted cytokine production, and reduced neutrophil infiltration in lung, colon, and liver. These beneficial effects of the PPARgamma ligands were associated with the reduction of IkappaB kinase complex and c-Jun NH(2)-terminal kinase activation and the reduction of NF-kappaB and AP-1 DNA binding in the lung. Furthermore, treatment with ciglitazone or 15d-PGJ(2) up-regulated the expression of PPARgamma in lung and thoracic aorta and abolished nitrotyrosine formation and poly(ADP-ribose) expression in aorta. Our data suggest that PPARgamma ligands attenuate the inflammatory response in sepsis through regulation of the NF-kappaB and AP-1 pathways.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Aorta, Thoracic; Bacteremia; Blood Glucose; Blood Pressure; Down-Regulation; I-kappa B Kinase; I-kappa B Proteins; Interleukin-10; Interleukin-6; Leukocyte Count; Ligands; Lung; Male; Microbodies; Mitogen-Activated Protein Kinase 8; Mitogen-Activated Protein Kinases; Neutrophil Infiltration; NF-kappa B; NF-KappaB Inhibitor alpha; Poly(ADP-ribose) Polymerases; Prostaglandin D2; Protein Serine-Threonine Kinases; Rats; Rats, Sprague-Dawley; Receptors, Cytoplasmic and Nuclear; Sepsis; Signal Transduction; Survival Rate; Thiazolidinediones; Transcription Factor AP-1; Transcription Factors; Tumor Necrosis Factor-alpha; Tyrosine