The Role Of IL-7 And RANKL/OPG In DSS-induced Mouse Colitis

BackgroundInflammatory bowel disease(IBD)is a recurrent chronic non-specific intestinal inflammatory disease,including Ulcerative colitis(UC)and Crohn's disease(CD).In recent years,the incidence of IBD in China has been increasing year by year.Studies have shown that the onset of IBD is associated with damage to the intestinal mucosal barrier and the persistence of multiple inflammatory factors.Interleukin-7(IL-7)secreted by intestinal epithelial cells regulates the survival and proliferation of mucosal lymphocytes.It also affects the role of the RANKL/OPG in inflammatory diseases.However,the role of the IL-7 and RANKL/OPG in the intestinal mucosal barrier of IBD remains to be further investigated.ObjectiveThe animal model of IBD was constructed.Explore the role of the IL-7 and RANKL/OPG in the colitis model.MethodsSPF grade,48 male Balb/c mice aged 6-8 weeks,were randomly divided into 4groups,12 in each group.(1)Normal control group: Free to eat and drink.(2)DSS model group: self-drinking 2.75% DSS solution for 9 days.(3)IL-7 solution + DSS model group: Freely drink 2.75% DSS solution,each mouse was intraperitoneally injected with 0.15 ml of IL-7 solution 5 ?g/ml on the 4th and 6th day.(4)IL-7 solution control group: freely eat and drink,intraperitoneal injection of IL-7 solution on day 4,day 6,same as(3).The statistical data was processed by statistical analysis software SPSS21.0.The measurement data were expressed as mean±standard deviation(mean±SD).After normal distribution test and homogeneity test of variance,multiple sets of quantitative data were analyzed by one-way ANOVA.The significance data can be compared between groups by LSD-t method;the rank sum test is used for multiple sets of ordered classification data;the correlation is analyzed by Pearson correlation coefficient.The test level ? = 0.05,and when P < 0.05,the difference was considered statistically significant.Results(1)DAI scores and HI scores of each group of mice: DSS model group was higher than normal control group(P<0.05);IL-7+DSS model group was lower than DSS model(P<0.05),compared with normal control group and IL-7 control group Group height(P<0.05).(2)IHC of Occludin,ZO-1,RANKL and OPG in colon tissues.There was no significant difference in the expression of Occludin,ZO-1 and IL-7 in the control group(P>0.05).Occludin and ZO-1: The DSS model group was less than the normal control group,and the staining was shallow(P<0.05).The IL-7+DSS model group had more expression than the DSS model group(P<0.05);RANKL and OPG: DSS model group showed more expression than the normal control group,and the staining was deep(P<0.05).The IL-7+DSS model group had less expression than the DSS model group,and the staining was shallow(P<0.05).(3)ELISA detection of serum RANKL,OPG expression levels: The expression of RANKL in serum is meaningless.The expression of OPG in the serum group washigher than that in the normal control group(P<0.05);The expression in the IL-7+DSS model group was lower than the DSS model group(P<0.05),higher than the normal control group and IL-7 control group(P < 0.05).Conclusions(1)The RANKL/OPG is involved in the pathogenesis of DSS-induced colitis in mice.(2)Recombinant cytokine IL-7 solution can partially inhibit the expression of RANKL and OPG in colon tissue,and to some extent alleviate DSS-induced inflammation of colitis.