Changes of regulatory T cells distribution in trinitrobenzene sulfonic acid induced mice colitis / 中华消化杂志

ABSTRACT

Objective To investigate the changes of regulatory T cells (Treg) distribution in trinitrobenzene sulfonic acid (TNBS) induced mice colitis and the therapeutic effects of dexamethasone (DEX).Methods A total of 40 mice were evenly divided into healthy control group,ethanol control group,model group and DEX treatment group.The model group was given 2.5 mg TNBS through enema,while healthy control group and ethanol control group were administered with 0.9％ NaCl solution and ethanol solution respectively.DEX treatment group was intraperitoneal injected with DEX (0.6 mg/kg) since the first day after modeling.Mice were executed at 3rd,5th and 7th day after modeling,mice body weight of each group were observed and the rate of both CD25+ forkhead box P3(Foxp3) positive and CD4 positive cells in spleen and mesenteric lymph nodes were measured by flowcytometry.At the 7th day,disease activity index (DAI) and colonic histopathological score were evaluated,the expression of Foxp3 in colon tissue were measured by immunohistochemistry.t-test was applied for each group comparison.Results Compared with healthy control group and ethanol control group,the mice body weight of model group significantly decreased (t=3.604 and 2.422,both P＜0.05); DAI score and colonic histopathologic score increased (t=2.630 and 2.438,both P＜0.05;t=7.910 and 6.600; both P＜0.01).Compared with the model group,DAI score decreased (t=2.076,P＞0.05) and histopathologic severity in DEX treatment group improved significantly (t =2.320,P＜0.05).At the 7th day after modeling,the rate of both CD25+ Foxp3 positive and CD4 positive cells in spleen and mesenteric lymph nodes of model group was 3.320％ ± 0.533％ and 2.888％±0.379％,lower than that of healthy control group (5.379％ ±0.518％ and 4.688％±0.553％; t=2.769 and 2.686; both P＜0.05).After DEX treatment,the rate increased.The expression of Foxp3 in colon tissue of healthy control group,model group and DEX treatment group was 3.000±0.577,7.200±0.800 and 6.000±0.931 per high power field respectively,and the expression of model group and DEX group significantly increased (t=4.257 and 2.739,both P＜ 0.05).Conclusions The distribution of Treg in spleen and colon were abnormal in TNBS-induced mice colitis model.DEX may improve the disease state of the mice model through upregulating Treg.