title: Augmentation of cytokine-induced nitric oxide synthesis by hydrogen peroxide.
abstract: The inducible isoform of nitric oxide synthase (iNOS) is induced upon stimulation of cells with cytokines and lipopolysaccharide (LPS). Stimulation of rat pleural mesothelial cells with combinations of interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), and LPS induced the synthesis of nitric oxide as measured by the oxidation products nitrite (NO2-) and nitrate (NO3-). Addition of 25-50 microM H2O2 to the cytokines significantly augmented the synthesis of NO2- and NO3-. Stimulation with IL-1 beta and TNF-alpha plus H2O2 or IL-1 beta and LPS plus H2O2 increased the synthesis of NO2- and NO3- by 3.8- and 3.5-fold, respectively. These effects were inhibited by NG-nitro-L-arginine methyl ester and cycloheximide as well as by catalase. Immunoblotting demonstrated that H2O2 augmented cytokine-induced synthesis of iNOS protein. These effects were inhibited by certain antioxidants and metal chelators, suggesting that the hydroxyl radical may mediate the oxidant-induced effect. Northern blotting demonstrated that H2O2 greatly augmented steady-state levels of iNOS mRNA, suggesting that H2O2 acted in part at the transcriptional level.
authors: Department of Medicine, Veterans Affairs Medical Center, Shreveport, Louisiana 71101, USA.
authors: S A
authors: SA
authors: Milligan
authors: M W
authors: MW
authors: Owens
authors: M B
authors: MB
authors: Grisham
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology*; D004357:Drug Synergism; D004790:Enzyme Induction; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D006706:Homeostasis; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics; D010994:Pleura / Q000166:cytology / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013997:Time Factors
chemical_list: D016207:Cytokines; D012333:RNA, Messenger; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D019001:Nitric Oxide Synthase