Peroxynitrite mediates cytokine-induced IL-8 gene expression and production by human leukocytes

Recent studies indicate that nitric oxide (NO) or related compounds may reg ulate the production of interleukin (IL)-8, a potent proinflammatory chemok ine, Here we report that peroxynitrite (ONOO-) formed by a reaction of NO w ith superoxide mediates IL-8 gene expression and IL-8 production in IL-1 be ta- and TNF-alpha -stimulated human leukocytes in whole blood. The NO synth ase inhibitors aminoguanidine and NG-nitro-L-arginine methyl eater blocked nuclear accumulation of activator protein-1 (AP-1) and nuclear factor (NF)- kappaB in both polymorphonuclear (PMN) and mononuclear leukocytes and inhib ited IL-8 mRNA expression and IL-8 release by similar to 90% in response to IL-1 beta and TNF-alpha. Enhanced ONOO- formation was detected in granuloc ytes, monocytes, and lymphocytes after challenge with IL-1 beta or TNF-alph a. The addition of ONOO- (0.2-80 muM) to whole blood increased nuclear accu mulation of AP-1 and NF-kappaB in PMN and mononuclear leukocytes and augmen ted IL-8 mRNA expression and IL-8 production in a concentration-dependent f ashion, Pyrrolidine dithiocarbamate, an inhibitor of NF-kappaB activation, attenuated similar to 70% of IL-8 release evoked by IL-1 beta, TNF-alpha, o r ONOO-. These results indicate that ONOO- formation may underlie the actio n of cytokines towards IL-8 gene expression in human leukocytes.