[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, glucocorticoid 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 mice which 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.