The Changes Of Tfh、Tfr Cells In Colitis Mice By Fecal Microbiome Transplantation

Objective:To observe the changes in the levels of follicular helper T cells(Tfh)and follicular regulatory T cells(Tfr)in the spleen of mice with ulcerative colitis after fecal microbiota transplantation intervention,and to explore the clinical significance of the intervention effect of fecal microbiota transplantation.Methods:45 female C57BL/6 mice were divided into normal control group,TNBS model group and faecal microbiota transplantation intervention group by random number table method.Mice in the Model group and intervention group were given 100 mg/kg trinitrobenzenesulfonic acid(TNBS)ethanol solution to enema for the preparation of ulcerative colitis model.Mice in the normal control group were given the same dose of 0.9%sodium chloride solution to enema.The fecal bacteria transplantation intervention lasted for 7 days after the successful modeling,and mice in the model group and the normal group were given an equal volume sterile 0.9%NaCl solution for enema for 7 days,during which the symptoms and signs of all groups of mice were observed.The spleen and colon tissue samples were collected and examined.UC disease activity index(DAI)was used to evaluate the body mass and stool status of mice.The histological changes of colonic mucosa in mice were observed by HE staining,and the damage of the colon tissue was evaluated.Expression levels of CD4,CXCR5,IL-21,BCL-6 and Foxp3mRNA in colon tissues of mice were detected by RT-PCR.Flow cytometry was used to detect CD4+CXCR5+PD-1+Tfh and CD4+CXCR5+Foxp3+Tfr cells in the spleen tissues.Result:In the process of mouse colitis modeling,mice in the model group and the intervention group showed decreased activity and diet,weight loss,loose stools and blood stools.The mice in the intervention group showed gradually improved symptoms after FMT.Compared with the normal group,DAI,CMDI,histological score,relative expression levels of CD4mRNA,BCL-6 mRNA and IL-21 mRNA in the colon tissues,the proportion of Tfh cells in the spleen and Tfh/Tfr in the model group were all higher than those in the normal group,with significant differences(all P<0.05).However,the Tfr cell ratio in the spleen and Foxp3mRNA expression of the model group were slightly higher than those of the normal group(P>0.05).Compared with the model group,DAI,CMDI,histological score,relative expression levels of CD4mRNA,BCL-6mRNA and IL-21 mRNA in colon tissues,the proportion of Tfh cells in spleen and Tfh/Tfr in the intervention group were all lower than those in the model group,with significant differences(all P<0.05).Tfr cell proportion and Foxp3mRNA expression in the intervention group were significantly higher than those in the model group(all P<0.05).Conclusion:The symptoms and signs of TNBS-induced colitis mice were significantly pathological compared with the normal group.DAI,CMDI,histological score,Tfh cell ratio and relative mRNA expression of Tfh cytokines were significantly increased in the model group,and the Tfh/Tfr ratio was increased.After intervention with fecal microbiota transplantation,DAI,CMDI and histological scores were improved,which had a certain impact on Tfh and Tfr in spleen tissue,and could improve the ratio of Tfh/Tfr,reduce the expression of Tfh promoting inflammation,and promote the expression of Tfr,thereby regulating and inhibiting the progression of inflammation.