Evidence for oxidative stress in NSAID-induced colitis in IL10−/− mice

The goal of this study was to evaluate for evidence of oxidative stress in colonic inflammation in a novel model of inflammatory bowel disease, nonsteroidal anti-inflammatory drug- (NSAID-) treated interleukin-10-deficient (IL10−/−) mice. IL10−/− and wild-type (wt) mice were treated with a nonselective NSAID (piroxicam, 200 ppm in the diet) for 2 weeks to induce colitis, and parameters for oxidative stress in the colonic tissues were evaluated. Mean chemiluminescence enhanced with lucigenin in the colons from IL10−/− mice treated with piroxicam was more than 5-fold higher than that of the control wt group. Chemiluminescence was inhibited with diphenylethylene iodinium, but not allopurinol, indomethacin, or N-ω-nitro-L-arginine, indicating that flavin-containing enzymes were the source of the reactive oxygen species. Colonic aconitase activity in NSAID-treated IL10−/− mice decreased to 50% of the activity of control mice. There was no difference in the total glutathione levels in the colonic mucosa among the groups; however, glutathione disulfide levels were approximately 2-fold greater in the colon of NSAID-treated IL10−/− mice as compared with control groups. Immunohistochemistry studies of colons from NSAID-treated IL10−/− mice demonstrated intense staining with two antibodies that recognize advanced glycation endproducts formed through glycation and oxidation: anticarboxymethylysine and antipentosidine. The epithelial cells and lamina propria cells in the colons of NSAID-treated IL10−/− mice showed immunostaining with antinitrotyrosine, indicating the presence of reactive nitrogen species. Colonic epithelium of IL10−/− mice with colitis showed moderate immunostaining for 8-hydroxy-2′-deoxyguanosine in the nuclei. NSAID-treated IL10−/− mice treated with diphenylene idodonium chloride (DPI), an irreversible inhibitor of flavoprotein enzymes, experienced significantly reduced inflammation. Taken together, these results strongly indicate the presence of oxidative stress in the inflammatory bowel disease in NSAID-treated IL10−/− mice and suggests a role for oxidative stress in the pathophysiology of this model of inflammatory bowel disease.