Role for complement in development of Helicobacter-induced gastritis in interleukin-10-deficient mice.

The mechanisms by which the immune response can eradicate gastric Helicobacter infection are unknown. We hypothesized that Helicobacter-induced activation of the complement system could promote both inflammation and eradication of Helicobacter from the stomach. In vitro studies demonstrated that Helicobacter felis activates complement in normal mouse serum but not in serum from Rag2(-/-) mice, indicating that H. felis activates complement through the classical pathway. Next, we infected complement-depleted wild-type control and interleukin-10-deficient (IL-10(-/-)) mice with H. felis. Helicobacter infection of wild-type mice elicited a mild, focal gastritis and did not alter serum complement levels. Infection of IL-10(-/-) mice with H. felis elicited severe gastritis. After the initial colonization, the IL-10(-/-) mice completely cleared Helicobacter from the stomach by day 8. In contrast to wild-type mice, H. felis-infected IL-10(-/-) mice had a marked increase in serum complement levels. Complement depletion of wild-type mice did not affect the intensity of gastric inflammation or the extent of Helicobacter colonization compared to that for the wild-type control mice. In contrast, complement depletion of Helicobacter-infected IL-10(-/-) mice decreased the severity of gastritis, decreased the Helicobacter-induced infiltration of neutrophils into the stomach, and delayed the clearance of bacteria. In vitro studies of stimulated splenocytes and neutrophils from IL-10(-/-) mice produced a twofold increase in complement production compared to that for wild-type mice. Pretreatment with IL-10 inhibited this increase. These studies identify a role for complement in the local immune response to gastric Helicobacter in IL-10(-/-) mice and suggest a role for IL-10 in the regulation of complement production.

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-omega-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.

Depletion of neutrophils in IL-10(-/-) mice delays clearance of gastric Helicobacter infection and decreases the Th1 immune response to Helicobacter.

Gastric infection with Helicobacter induces a lymphocyte-rich mucosal inflammation that contains a minor population of neutrophilic granulocytes. The function of neutrophils in the local immune response to gastric Helicobacter infection remains unknown. To investigate this issue, we conducted experiments in neutrophil-depleted control wild-type (wt) and IL-10(-/-) mice infected with Helicobacter felis by gastric lavage. Infection of wt mice elicited a mild, focal gastritis and a Helicobacter-specific Th1 immune response. In wt mice Helicobacter colonization of the stomach was persistent and progressively increased during the 29 days of observation. Infection of IL-10(-/-) mice with H. felis elicited a severe chronic gastritis and a greatly enhanced Helicobacter-specific Th1 immune response, as compared with wt mice. After initial colonization, the IL-0(-/-) mice completely cleared Helicobacter from the stomach by day 8. The gastric inflammation in wt and IL-10(-/-) mice contained modest numbers of neutrophils. The intensity of gastric inflammation and the extent of Helicobacter colonization were similar in control and in neutrophil-depleted wt mice. In contrast, neutrophil depletion of Helicobacter-infected IL-10(-/-) mice decreased the severity of gastritis, modulated the Helicobacter-specific Th1 immune response, and delayed the clearance of bacteria from the stomach. These studies identify a role for neutrophils in the local and systemic immune response to gastric Helicobacter in IL-10(-/-) mice.

Rapid development of colitis in NSAID-treated IL-10-deficient mice.

BACKGROUND & AIMS: Interleukin (IL)-10 is an anti-inflammatory and immune regulatory cytokine. IL-10-deficient mice (IL-10(-/-)) develop chronic inflammatory bowel disease (IBD), indicating that endogenous IL-10 is a central regulator of the mucosal immune response. Prostaglandins are lipid mediators that may be important mediators of intestinal inflammation. In this study we assessed the role of prostaglandins in the regulation of mucosal inflammation in the IL-10(-/-) mouse model of IBD. METHODS: Prostaglandin (PG) synthesis was inhibited with nonselective or cyclooxygenase (COX)-isoform selective inhibitors. Severity of inflammation was assessed histologically. Cytokine production was assessed by ribonuclease protection analysis and enzyme-linked immunosorbent assay. PGE(2) levels were assessed by enzyme immunoassay. COX-1 and COX-2 expression was assessed by Western blot analysis. RESULTS: Nonsteroidal anti-inflammatory drug (NSAID) treatment of wild-type mice had minimal effect on the colon. In contrast, NSAID treatment of 4-week-old IL-10(-/-) mice resulted in rapid development of colitis characterized by infiltration of the lamina propria with macrophages and interferon gamma-producing CD4(+) T cells. Colitis persisted after withdrawal of the NSAID. NSAID treatment decreased colonic PGE(2) levels by 75%. Treatment of IL-10(-/-) mice with sulindac sulfone (which does not inhibit PG production) did not induce colitis whereas the NSAID sulindac induced severe colitis. COX-1- or COX-2-selective inhibitors used alone did not induce IBD in IL-10(-/-) mice. However, the combination of COX-1- and COX-2-selective inhibitors did induce colitis. CONCLUSIONS: NSAID treatment of IL-10(-/-) mice results in the rapid development of severe, chronic IBD. Endogenous PGs are important inhibitors of the development of intestinal inflammation in IL-10(-/-) mice.

Established T(H1) granulomatous responses induced by active Mycobacterium avium infection switch to T(H2) following challenge with Schistosoma mansoni.

Mycobacterium avium established a systemic infection with granulomatous inflammation in mice. Mice chronically infected with M. avium and subsequently co-infected with Schistosoma mansoni developed additional, but morphologically distinct, hepatic granulomas. Schistosome eggs were not deposited in the spleen, and splenic granulomas in co-infected mice contained mycobacteria. In complete contrast to the T(H1) cytokine pattern observed with granuloma lymphocytes from M. avium-infected mice, granuloma lymphocytes from co-infected mice stimulated with PPD elaborated IL-4, but not IFN-gamma. Furthermore, mycobacterial granulomas in concurrently infected mice contained large numbers of eosinophils, a feature never seen in granulomas of M. avium-infected mice. Serum IgG1 and IgE levels in concurrently infected mice were significantly higher, but IgG2a levels significantly lower, than those in M. avium-infected mice, further evidence that the T(H1) component induced by M. avium is modulated subsequent to co-infection with S. mansoni. The dominance of the T(H2) response observed in this model could have clinical implications in areas where parasites and mycobacteria co-exist.

Female sex hormones as regulatory factors in the vaginal immune compartment.

Sexually transmitted diseases (STD) are now considered to be among the most common human infections. The incidence of STD is on the rise, which is partly due to frequent transmission during the asymptomatic phase of infection. The compounded cost of STD just in the United States is estimated to exceed $10 billion annually. STD are particularly prevalent in teenagers and young adults and the health problems caused by these diseases tend to be more severe and more frequent in woman than in men. Despite considerable efforts, a vaccine that provides protective immunity against sexually transmitted diseases in humans has not been developed. Nonetheless, research in animal models indicates that strong local and regional immune responses can influence the outcome of vaginal challenge with microbial pathogens. Vaginal immunity is an area of basic immunology that has received relatively little attention, but it is already clear that the mucosal and regional immunology of the vagina has unique features. The present review summarizes some of the anatomical, physiological and immunological features of the vagina and uterus that distinguish humans, non-human primates, rats and mice. These interspecies differences need to be taken into account in laboratory efforts to develop effective vaccines for STD in humans.