NOD小鼠自然状态下CD4~+CD25~+T细胞的动态变化及意义

研究自发的1型糖尿病雌鼠模型(NOD)在自然状态下发生1型糖尿病过程中CD4+CD25+T细胞的动态变化,旨在初步探讨调节性T细胞参与1型糖尿病发病的可能机制。采用雌性NOD小鼠作动物模型,每2周尾静脉采血1次,采用三色流式细胞术测定NOD小鼠外周血中CD4+CD25+T细胞(CD3+CD4+CD25+)的百分率。在32周时,对比发生糖尿病和未发生糖尿病NOD小鼠不同脏器中的CD4+CD25+T细胞阳性率。HE法检测胰岛炎。结果显示:(1)自第6周起NOD小鼠CD4+CD25+T细胞百分率逐渐降低。发生糖尿病NOD小鼠CD4+CD25+T细胞比率低于未发病NOD小鼠对照组(外周血分别为0.94%±0.21%、1.62%±0.23%,P=0.01;脾脏2.09%±0.14%、2.77%±0.36%,P=0.019),提示糖尿病NOD小鼠外周血中存在异常比例的CD4+CD25+T细胞;(2)32周龄糖尿病NOD小鼠与未发病NOD小鼠的CD4+CD25+T细胞抑制功能减低,与阳性对照组有显著性差异;(3)HE染色结果示糖尿病NOD小鼠胰岛结构完全破坏,胰岛炎程度较未发病NOD小鼠严重。该结果提示NOD小鼠发生糖尿病时免疫功能紊乱与CD4+CD25+T细胞参与调节及T细胞亚群变化相关,糖尿病的发生受致病性T细胞和调节性T细胞的调节。

Dynamic change of CD4+CD25+ T cells in non-obese diabetic mice under natural condition

To investigate the dynamic change of CD4+CD25+ T cells in non-obese diabetic mice(NOD) to develop type 1 diabetes mellitus and explore the possible mechanism of the regulatory T cells participating the pathogenesis of diabetes,the percentage of CD3+CD4+CD25+ T cells in peripheral blood of female NOD mice was determined every 2 weeks with TC-CD3,FITC-CD4 and PE-CD25 antibodies staining and analyzed by flow cytometry.Spleen cell suspensions were enriched for CD4+ T cells by panning and were sorted on FACS into CD4+CD25+ and CD4+CD25-T cells.At 32 weeks old of mice,the percentage of CD4+CD25+ T cells in different organs of NOD mice with or without diabetes was compared and the HE staining was used to detect the presence of insulitis assessed for each islet.It was found that the percentage of CD4+CD25+ T cells in NOD mice gradually reduced,and the ratio of this subpopulation of T cells in NOD mice with diabetes was lower than that of normal NOD mice without diabetes,indicating the presence of the abnormal ratio of CD4+CD25+ T cells in the peripheral blood of NOD mice with diabetes.The suppressive function of CD4+CD25+ T cells of the 32 weeks old of NOD mice with diabetes and without diabetes also reduced and significant difference existed with the positive control group.As demonstrated by HE staining,the structure of the pancreatic islets was completely destroyed in NOD mice with diabetes and the degree of the structural destruction in insulitis was graver than that of NOD mice without diabetes.From these observations,it is evident that the progression to overt diabetes correlates with the age-dependent reduction in the number of CD4+CD25+ T cells and its deficiency in functions to maintain the tolerance to islet auto-antigen effectively.The result of this investigation gives a direct evidence to support the fact that CD4+CD25+ Tregs contribute to the development of autoimmune diabetes.