Regulation of interleukin 8 gene expression by oxidant stress.
Interleukin 8 (IL-8) is a recently described cytokine that functions as a potent neutrophil chemoattractant and activator. We sought to examine the link between the generation of reactive oxygen intermediates (ROI) and the regulation of IL-8 gene expression to specifically test the hypothesis that ROI would induce production of IL-8 mRNA and protein. In lipopolysaccharide-stimulated human whole blood, the OH radical scavenger dimethyl sulfoxide (Me2SO) dramatically inhibited (approximately 90%) IL-8 production, but had minimal effects on the production of tumor necrosis factor, interleukin 1 beta (IL-1), and IL-6. To determine whether NADPH-oxidase-generated free radicals were critical in the regulation of IL-8, studies were performed using blood from patients with chronic granulomatous disease. In both normal individuals and patients with chronic granulomatous disease, production of IL-8 could be initiated with lipopolysaccharide, phytohemagglutinin, or aggregated immune complexes, and this production could be inhibited by Me2SO (1% v/v). To examine if oxidant stress represents a ubiquitous mechanism for the induction of IL-8, experiments were performed in cultured cell lines. In the human hepatoma cell line Hep-G2, Me2SO dose-dependently inhibited tumor necrosis factor-stimulated IL-8 production, with a 74 +/- 1% reduction observed at a Me2SO concentration of 1%. Direct exposure to ROI demonstrated that H2O2 stimulated IL-8 production in a dose-dependent manner in Hep-G2 cells, A549 pulmonary type II epithelial cells, and human skin fibroblasts; this induction could be prevented by addition of catalase. The production of IL-8 appeared to be specific to an oxidant stress since exposure of the cells to heat shock or chemical stress did not induce expression of IL-8. These studies demonstrate that oxidant stress is an important regulator of IL-8 gene expression and support the hypothesis that low levels of ROI may serve to initiate IL-8 production which then serves to recruit neutrophils to sites of inflammation.
DeForge
L E
LE
Department of Pathology, University of Michigan Medical School, Ann Arbor 48109.
Preston
A M
AM
Takeuchi
E
E
Kenney
J
J
Boxer
L A
LA
Remick
D G
DG
D000975:Antioxidants / Q000494:pharmacology*; D001483:Base Sequence; D015152:Blotting, Northern; D006528:Carcinoma, Hepatocellular; D002460:Cell Line; D002470:Cell Survival; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D016166:Free Radical Scavengers; D005609:Free Radicals / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D006105:Granulomatous Disease, Chronic / Q000097:blood* / Q000235:genetics; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007231:Infant, Newborn; D016209:Interleukin-8 / Q000096:biosynthesis*; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008113:Liver Neoplasms; D008168:Lung; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000097:blood; D019255:NADPH Oxidases; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015345:Oligonucleotide Probes; D016877:Oxidants / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D012867:Skin / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D000975:Antioxidants; D016166:Free Radical Scavengers; D005609:Free Radicals; D016209:Interleukin-8; D008070:Lipopolysaccharides; D015345:Oligonucleotide Probes; D016877:Oxidants; D012333:RNA, Messenger; D006861:Hydrogen Peroxide; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D004121:Dimethyl Sulfoxide