1型糖尿病与脾脏CD4^+CD25^+调节性T细胞及相关基因Foxp3表达的关系

Relationship of type 1 diabetes mellitus with CD4^+CD25^+regulatory T cells and expression of its related gene Foxp3

目的:研究链脲佐菌素(streptozotocin,STZ)诱导糖尿病小鼠发病中CD4+CD25+调节性T细胞(regulatoryTcell,Tr)及相关基因Foxp3表达的变化,从而探讨CD4+CD25+Tr在自身免疫耐受中的作用。方法:实验选用健康昆明小鼠60只,将60只小鼠随机分对照组(n=20)和模型组(n=40)。模型组给与腹腔注射6g/LSTZ溶液,60mg/(kg·d),连续5d;对照组给予枸橼酸钠缓冲液0.2mL/d腹腔注射,连续5d。流式细胞仪检测脾脏CD4+和CD4+CD25+Tr细胞数量的变化,RT-PCR检测脾小鼠脾脏细胞中CD4+CD25+Tr细胞相关基因Foxp3mRNA的表达。结果:模型组血糖和抗胰岛素抗体水平明显高于对照组(t=0.023,P<0.05;t=0.018,P<0.05);模型组小鼠脾脏CD4+T细胞数量犤(29.69±4.77)%犦明显高于对照组犤(19.60±11.42)%犦(t=0.014,P<0.05),模型组CD4+CD25+Tr/CD4+T比值低于对照组;Foxp3mR-NA水平模型组的表达普遍高于对照组。结论:CD4+CD25+Tr细胞的相对降低,引起外周耐受状态的打破;在STZ破坏胰岛细胞,自身抗原存在的同时,导致了自身免疫糖尿病的发生。

AIM:To investigate the changes of CD4+CD25+regulatory T cells(Tr) in streptozotocin(STZ)-induced diabetic mice, so as to probe into the mechanism of CD4+CD25+Tr in autoimmune tolerance. METHODS:Sixty healthy Kunming mice were randomly divided into control group(n=20) and model group(n=40).Mice in the model group and control group were treated with intraperitoneal injection of STZ(60 mg/kg per day) and sodium citrate buffer(0.2 mL per day) for 5 days successively respectively.The changes of numbers of CD4+Tr and CD4+CD25+Tr were detected with flow cytometer,and the level of Foxp3 mRNA expression of CD4+CD25+Tr in spleen was determined with reverse transcriptase-polymerase chain reaction(RT-PCR). RESULTS:The levels of blood glucose and anti-insulin were obviously higher in the model group than in the control group(t=0.023, P< 0.05;t=0.018,P< 0.05).The number of CD4+Tr in spleen of mice was markedly higher in the model group[(29.69±4.77)%] than in the control group[(19.60±11.42)%](t=0.014,P< 0.05),while the rate of CD4+CD25+Tr/CD4+T was lower and the level of Foxp3 mRNA expression was higher in the model group than in the control group. CONCLUSION:The relative reduce of CD4+CD25+Tr can lead to the breakdown of peripheral autoimmune tolerance.STZ destroys insulin and existence of self-antigen, meanwhile,results in the occurrence of autoimmune diabetes mellitus.