糖皮质激素对哮喘小鼠CD4+CD25+调节性T细胞的作用

目的：建立哮喘小鼠动物模型并给予吸入糖皮质激素治疗，通过分析CD4+CD25+调节性T细胞及相关细胞因子在哮喘发病中的变化情况，以及观察糖皮质激素治疗对该细胞的影响和干预作用，探讨哮喘发作的新的免疫机制。方法：分别制备哮喘组（OVA），哮喘吸入激素治疗组（OVA/GC）及对照组（NS）动物模型。所有小鼠于末次激发后24 h，取右肺中叶标本作病理切片，观察炎症改变；同时收集外周抗凝血及肺组织细胞悬液，通过流式细胞仪及酶联免疫吸附试验（ELISA）测定CD4+CD25+调节性T细胞占CD4+ T细胞的百分比和血浆中IL-10和TGF-β1水平。结果：①哮喘小鼠外周血及肺组织细胞悬液中CD4+CD25+调节性T细胞百分率明显降低（P<0.01），吸入糖皮质激素治疗后CD4+CD25+调节性T细胞百分率明显升高（P<0.01）。②IL-10在哮喘组较对照组明显降低（P<0.01），糖皮质激素治疗组IL-10明显升高（P<0.01）。③TGF-β1在哮喘小鼠较对照组明显降低（P<0.01），吸入糖皮质激素治疗后TGF-β1有所升高，但差异无显著性。结论： ①哮喘小鼠CD4+CD25+调节性T细胞和IL-10，TGF-β1数量和分泌水平降低，尤其是肺部CD4+CD25+调节性T细胞不能有效聚集，导致全身和局部对炎症反应的抑制作用减弱，可能是导致哮喘发生的原因之一。②糖皮质激素可通过增加CD4+CD25+调节性T细胞及IL-10数量和分泌水平，增强其免疫抑制功能而发挥治疗作用。③外周血和肺部CD4+CD25+调节性T细胞百分率变化具有一致性，监测外周血CD4+CD25+调节性T细胞变化情况可以了解肺部变化趋势。

Effect of glucocorticoid on CD4+CD25+ T regulatory cells in asthmatic mice

OBJECTIVE: To determine the changes of CD4+CD25+ regulatory T cells and the levels of IL-10 and TGF-beta1 in the mouse model of asthma and the effects of glucocorticoid inhalation on CD4+CD25+ regulatory T cells and IL-10 and TGF-beta1 levels. METHODS: Thirty BALB/c mice were randomly divided into three groups: asthma model, glucocor-ticoid treatment and control. Asthma was induced by OVA administration in the asthma model and the glucocorticoid treatment groups. The glucocorticoid treatment group received budesonide inhalation (0.8 mg/L) before the challenge of asthma. After 24 hrs of the last challenge, the lung tissues of middle lobe of the right lung were obtained for the observation of lung pathological changes. Peripheral anticoagulated blood and lung lymph cells suspension were collected. The percentage of CD4+CD25+ regulatory T cells in CD4+ T cells was detected by flow cytometry, and the levels of IL-10 and TGF-beta1 in plasma were measured using ELISA. RESULTS: The percentage of CD4+CD25+ regulatory T cells in peripheral blood and lung lymph cells suspension in the asthma model group was significantly lower than the control group ( P<0.01). The glucocorticoid-treated asthma group showed an increased percentage of CD4+CD25+ regulatory T cells compared with the asthma model group (P<0.01) and a similar percentage of CD4+CD25+ regulatory T cells in peripheral blood and lung lymph cells suspension to the control group. Compared with the control group, plasma levels of IL-10 and TGF-beta1 decreased significantly in the asthma model group (P<0.01). After glucocorticoid treatment plasma IL-10 level increased significantly (P<0.01) and was similar to that in the control group, while plasma TGF-beta1 level remained lower than that in the control group. CONCLUSIONS: The percentage of CD4+CD25+ regulatory T cells and the levels of IL-10 and TGF-beta1 decreased in asthmatic micewhich might contribute to the pathogenesis of asthma. Glucocorticoid can increase the percentage of CD4+CD25+ regulatory T cells and the levels of IL-10 and thus provides protective effects against asthma. The changes of the percentage of CD4+CD25+ regulatory T cells in peripheral blood were consistent with those in the lung, suggesting that monitoring the changes of CD4+CD25+ regulatory T cells in peripheral blood may be useful to understand the changes of CD4+CD25+ regulatory T cells in the lung.