title: Peroxynitrite mediates IL-8 gene expression and production in lipopolysaccharide-stimulated human whole blood.
abstract: Recent evidence indicates that free oxygen radicals, in particular hydroxyl radicals, may act as intracellular second messengers for the induction of IL-8, a potent chemoattractant and activator of neutrophil granulocytes. Here we report that peroxynitrite (ONOO-), formed by a reaction of nitric oxide (NO) with superoxide, mediates IL-8 gene expression and IL-8 production in LPS-stimulated human whole blood. The NO synthase inhibitors aminoguanidine and NG-nitro-L-arginine methyl ester (L-NAME) blocked IL-8 release by approximately 90% in response to LPS (1 microg/ml), but did not affect the production of IL-1beta or TNF-alpha. Both aminoguanidine and L-NAME blocked the induction of IL-8 mRNA by LPS. Authentic ONOO- (2.5-80 microM) augmented IL-8 mRNA expression and stimulated IL-8 release in a concentration-dependent manner, whereas the NO-releasing compounds, S-nitroso-N-acetyl-DL-penicillamine and sodium nitroprusside failed to induce cytokine production. Combination of the NO-generating chemicals with a superoxide-generating system (xanthine/xanthine oxidase) markedly increased IL-8 release. Enhanced ONOO- formation was detected in granulocytes, monocytes, lymphocytes, and plasma after challenge with LPS. Furthermore, pyrrolidine dithiocarbamate, an inhibitor of activation of nuclear factor-gammaB, markedly attenuated the induction of IL-8 mRNA expression and IL-8 release by either LPS or ONOO-. Our study identifies ONOO- as a novel signaling mechanism for IL-8 gene expression and suggests that inhibition of ONOO- formation or scavenging ONOO- may represent a novel therapeutic approach to inhibit IL-8 production that could lead to reduction of neutrophil accumulation and activation.
authors.affiliation: Research Center, Maisonneuve-Rosemont Hospital, University of Montreal, Quebec, Canada. filepj@ere.umontreal.ca
authors.forename: J G
authors.initials: JG
authors.lastname: Filep
authors.forename: M
authors.initials: M
authors.lastname: Beauchamp
authors.forename: C
authors.initials: C
authors.lastname: Baron
authors.forename: Y
authors.initials: Y
authors.lastname: Paquette
mesh_terms: D000328:Adult; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D006146:Guanidines / Q000494:pharmacology; D006801:Humans; D017665:Hydroxyl Radical / Q000097:blood / Q000494:pharmacology; D016209:Interleukin-8 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000097:blood / Q000235:genetics*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009566:Nitrates / Q000097:blood* / Q000502:physiology; D009569:Nitric Oxide / Q000502:physiology; D011759:Pyrrolidines / Q000494:pharmacology; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D013859:Thiocarbamates / Q000494:pharmacology
chemical_list: D006146:Guanidines; D016209:Interleukin-8; D008070:Lipopolysaccharides; D009566:Nitrates; D011759:Pyrrolidines; D012333:RNA, Messenger; D013859:Thiocarbamates; C020972:pyrrolidine dithiocarbamic acid; C039642:peroxynitric acid; D009569:Nitric Oxide; D017665:Hydroxyl Radical; C004479:pimagedine; D019331:NG-Nitroarginine Methyl Ester