H.Pylori Attenuates TNBS-induced Colitis Via Increasing Mucos Th2 Cells In Mice

Background and ObjectiveCrohn's disease(CD),one type of inflammatory bowel disease(IBD),is a life-long,chronic and relapsing disease that may occur anywhere in the gastrointestinal tract.Although its pathogenesis is still poorly understood,genetic predisposition and environment,most notably the gut microorganism were thought to be the important aetiology.However,up to now there is no decisive evidence of an etiologic role for any specific microbe.Whether there is a still unidentified specific microbe implicated in the pathogenesis of CD deserves to be explored.Interestingly,H.pylori was recently isolated and detected in the intestinal mucosa of patients with CD.Additionally,many recent studies have reported that CD patients have lower prevalence of H.pylori infection.Furthermore,some reports have shown that there are rapid and clinical onset of CD after eradication of H.pylori infection.Although these researches found an inverse relationship between H.pylori infection and CD,whether H.pylori plays a protective role against CD and the potential protective mechanism remain unclear.MethodsAnimal studiesMale BALB/c mice aged 6-8 weeks were used in this study.For TNBS group,100 ?l of 2.5%TNBS solution was administrated into the mouse colonic lumen.For TNBS+HP group,500 ?l of H.pylori enema was administrated into the mouse colonic lumen continuous 3 days after administration of 100 ?l of TNBS solution.For saline or HP control group,these control studies only used saline and HP enemas,respectively.Body weight(%starting weight),bleeding and stool consistency were measured as clinical parameters to calculate a disease activity score.All harvested mice were sacrificed and subsequently,their colons were intactly removed.The colons were longitudinally opened,cleaned and weighted after their length was measured.Body weight(%starting weight),bleeding and stool consistency were measured as clinical parameters to calculate a disease activity score.Colonic tissue were used for real-time PCR assay,HE and flow cytometry.Statistical analysisThe results are shown as the mean ± standard deviation.Statistical significance was determined by one-way analysis of variance with Tukey's multiple comparisons under equal variances or with Dunnett T3's multiple comparisons under unequal variances.a value of P<0.05 was considered to be statistically significant.ResultsAdministration of H.pylori attenuates the severity of TNBS-induced colitisAfter administration of NCTC11639 enema,the TNBS-treated mice displayed less weight loss,less bleeding,greater stool consistency and low disease activity scores and had decreased colonic:body weight.Consistent with the weight changes in the H.pylori-treated mice,the TNBS-treated mice displayed less thickened edematous colonic walls and less mucosal ulcerations after administration of NCTC11639 enema,especially at distal 4-6 cm from the anus.Together,these results confirm that administration of H.pylori can attenuate the severity of TNBS-induced colitis.Administration of H.pylori down-regulates Th17 and Thl cytokine expression,but up-regulates Th2 cytokine expression in murine colonic mucosaThe colonic mRNA expression of Th17-related cytokines(IL-23p19,IL-17A,IL-6,IL-10,TGF-? and STAT-3)was significantly lower in the mice treated with TNBS+NCTC11639 than in the mice treated with TNBS only.Similarly,the colonic mRNA expression of Thl-related cytokines(IL-12p35,TNF-?,IFN-? and STAT-1)was significantly lower in the mice treated with TNBS+NCTC11639 than in the mice treated with TNBS only.However,the changes of Thl-related cytokines were far weaker than the changes of Th17-related cytokines.Interestingly,the colonic mRNA expression of Th2-related cytokines(IL-4,IL-5,IL-10 and STAT-6)was significantly higher in the mice treated with TNBS+NCTC11639 than in the mice treated with TNBS only.Together,these results provide evidence that H.pylori can attenuate the severity of TNBS-induced colitis mainly through regulating the Th1 7 and Th2 lymphocyte responses.Administration of H.pylori increases the Th2:Th17 ratio of CD4+ T in murine colonic mucosaThe mice treated with TNBS+NCTC11639 had decreased levels of Th17 cells,increased levels of Th2 cells and increased Th2:Thl7 ratio of CD4+ T in colonic mucosa compared with the mice treated with TNBS only.These results suggest that H.pylori might inhibit and promote the differentiation of Th17 and Th2 to attenuate the severity of TNBS-induced colitis,respectively.ConclusionsAdministration of H.pylori enema can attenuate the severity of TNBS-induced colitis.Administration of H.pylori enema can down-regulate Th17 and Thl cytokine expression,and up-regulate Th2 cytokine expression in murine colonic mucosa;Administration of H.pylori can increase the Th2/Th17 ratio of CD4+ T in murine colonic mucosa.