大鼠急性脑缺血后CD4~+CD25~+调节性T细胞、Foxp3表达及其意义

目的动态观察大鼠急性脑缺血后不同时期外周血中CD4+CD25+调节性T细胞和脑组织中Foxp3的表达,探讨其在急性缺血性卒中病理生理演变过程中的作用。方法 48只Wistar大鼠按随机数字表法分为缺血组和假手术组。参考改良的Zea-Longer插线方法将缺血组大鼠制作成右侧大脑中动脉线栓脑缺血动物模型。采用流式细胞术和免疫组化染色检测造模后1、3、7、14 d时大鼠外周血中CD4+CD25+调节性T细胞表达和脑组织中Foxp3表达,同时采用改良NSS神经功能评分观察大鼠行为学变化。结果缺血组和假手术组大鼠神经功能缺损评分在模型制备后逐渐下降(P<0.01)。流式细胞术显示脑缺血后1、3 d时缺血组大鼠外周血中CD4+CD25+调节性T细胞的表达与假手术组比较差异无统计学意义(P>0.05),7、14 d时表达明显高于假手术组(P<0.05),且与大鼠的神经功能评分呈负相关(r=-0.68,P=0.01)。免疫组化显示脑缺血后1 d时缺血组大鼠脑组织中即可观察到Foxp3表达,且主要集中在缺血灶区域,在未缺血侧也可观察到Foxp3表达,但表达量较少,而假手术组脑组织中未见Foxp3表达。结论 CD4+CD25+调节性T细胞参与了大鼠急性脑缺血后炎症免疫反应的发生发展过程,且在脑缺血后1 d时便开始参与脑缺血性损伤的免疫调节,这种免疫调节对脑细胞有着保护作用。

Role of CD4(+)CD25(+) regulatory T cells and Foxp3 in the pathophysiology of acute cerebral ischemia in rats

Objective To investigate the dynamic changes in CD4+CD25+ regulatory T cells and Foxp3 expression in peripheral blood and brain tissues of rats after acute cerebral ischemia and explore their role in the pathophysiological evolution of acute ischemic stroke.Methods Forty-eight Wistar rats were randomized equally into ischemia and sham-operated groups,and right middle cerebral artery occlusion was induced in the former group.Flow cytometry and immunohistochemistry were employed to detect CD4+CD25+ T cells and Foxp3 expression,respectively,in the peripheral blood and brain tissue at 1,3,7,and 14 days after modeling.The behavioral changes of the rats were evaluated using an improved NSS neurological functional scoring system.Results The neurological function scores of the two groups both gradually declined after the operation,and showed significant differences between the two groups at all the time points of measurement(P<0.01).The CD4+CD25+ T cells in the peripheral blood were similar between the two group at 1 and 3 days after the operation(P>0.05),but increased significantly in the ischemia group at 7 and 14 days(P<0.05) with an inverse correlation to the neurological scores(r=-0.68,P=0.01).Immunohistochemistry detected the presence of Foxp3 primarily in the ischemic region of the brain tissue 1 day after cerebral ischemia;the contralateral hemisphere also showed a small quantity of Foxp3 expression.No Foxp3 expression was detected in the brain tissue of the sham-operated group.Conclusion CD4+CD25+ T regulatory cells participate in the inflammatory immune reactions as early as 1 day after acute cerebral ischemia in rats,which might be a protective mechanism of the brain cells.