Interaction between nitric oxide, reactive oxygen intermediates, and peroxynitrite in the regulation of 5-lipoxygenase metabolism.
We have shown that overnight lipopolysaccharide (LPS) suppresses alveolar macrophage (AM) leukotriene (LT) synthesis mediated in part by induction of inducible nitric oxide synthase (iNOS) and NO production. Here we examined the possibility that reactive oxygen intermediates (ROI) generated by LPS pretreatment contribute to the suppression of 5-lipoxygenase (5-LO) metabolism. Pretreatment of AM with xanthine/xanthine oxidase, which generates high concentrations of ROI, resulted in suppression of LT synthetic capacity. Since NO and ROI reactive species are known to react and form peroxynitrite (ONOO(-)), we examined the effect of ONOO(-) on 5-LO metabolism. Exogenous ONOO(-) caused a dose-dependent suppression of recombinant 5-LO cell-free activity. ONOO(-) also suppressed LT synthesis in intact AM, which was reversed by the ONOO(-) scavenger tetrakis(4-benzoic acid)porphyrin. ONOO(-) treatment also resulted in dose-dependent nitrotyrosination and S-nitrosylation of the recombinant 5-LO enzyme. Since the direct 5-LO inhibitor zileuton prevents the LPS-induced suppression of LT synthesis, we examined if 5-LO itself was the source of ROI. Zileuton reduced ROI generation in LPS-treated cells. These studies identify an important role for ROI and ONOO(-) in the suppression of 5-LO metabolism by LPS.
Coffey
Michael J
MJ
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical Center, 6301 MSRB III, 1150 W. Medical Center Dr., Ann Arbor, MI 48109-0642, USA. coffeym@umich.edu
Phare
Susan M
SM
Peters-Golden
Marc
M
D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D015536:Down-Regulation; D005260:Female; D016166:Free Radical Scavengers / Q000494:pharmacology; D006861:Hydrogen Peroxide; D006918:Hydroxyurea / Q000031:analogs & derivatives* / Q000494:pharmacology; D015289:Leukotrienes / Q000096:biosynthesis; D008070:Lipopolysaccharides; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism* / Q000494:pharmacology; D014969:Xanthine Oxidase
D016166:Free Radical Scavengers; D015289:Leukotrienes; D008070:Lipopolysaccharides; D016859:Lipoxygenase Inhibitors; D017382:Reactive Oxygen Species; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D001094:Arachidonate 5-Lipoxygenase; D014969:Xanthine Oxidase; C063449:zileuton; D006918:Hydroxyurea