Apoptosis and nitrative stress associated with phosphodiesterase inhibitor-induced mesenteric vasculitis in rats.
Nitric oxide may play a role in phosphodiesterase (PDE) inhibitor-induced rat mesenteric vasculitis. The present study was conducted to identify cellular sources of iNOS, determine the distribution of nitrotyrosine (NT) residues as a footprint of peroxynitrite (ONOO-) production, and evaluate their association with vascular apoptosis. To dissociate primary events from secondary changes associated with the inflammatory response, rats were given the PDE IV inhibitor CI-1018 orally at 750 mg/kg alone or concurrently with dexamethasone (DEX) intraperitoneally at 1 mg/kg for 4-5 days. Neutrophil (PMN) involvement in apoptosis was investigated in CI-1018 treated rats dosed with rabbit anti-rat PMN serum (APS). iNOS expression, NT residues, and caspase-3 were detected by immuno-histochemistry. Apoptosis was evaluated by TUNEL assay. CI-1018 induced vascular lesions were associated with iNOS expression in endothelial cells and inflammatory infiltrates; NT was evident only in the latter. Caspase-3 and TUNEL-positive staining were prominent only in medial smooth muscle cells (SMC) from CI-1018-treated rats and only when associated with active inflammation. iNOS- and NT-positive inflammatory cells were present in close proximity to SMC with caspase-3 staining. Inflammatory infiltrates were absent in rats given DEX with minimal SMC necrosis and hemorrhage remained. DEX eliminated apoptosis and immunoreactivity associated with caspase-3, iNOS, and NT. APS depletion of PMNs decreased the incidence and severity of vasculitis but failed to abolish completely caspase-3 immunoreactivity. Expression patterns for caspase-3, iNOS, and NT demonstrated that nitrative stress is a prominent feature of PDE inhibitor-induced vasculitis, with a possible role in medial SMC apoptosis. Further, medial SMC apoptosis may not be a primary event, but instead may be secondary to the inflammatory response.
Departments of Drug Safety Evaluation, Pfizer Global Research and Development, Ann Arbor Laboratories, Ann Arbor, Michigan 48105, USA.
Rabih M
RM
Slim
Yunling
Y
Song
Mudher
M
Albassam
Lloyd A
LA
Dethloff
D000284:Administration, Oral; D000818:Animals; D000961:Antilymphocyte Serum / Q000276:immunology / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology; D004359:Drug Therapy, Combination; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D005260:Female; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D007274:Injections, Intraperitoneal; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D018384:Oxidative Stress / Q000187:drug effects*; D030421:Peroxynitrous Acid / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism; D014657:Vasculitis / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology
D000961:Antilymphocyte Serum; D010726:Phosphodiesterase Inhibitors; D030421:Peroxynitrous Acid; C002744:3-nitrotyrosine; D014443:Tyrosine; D003907:Dexamethasone; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases