吸入糖皮质激素对哮喘儿童外周血Foxp3+调节性T细胞及IL-2、IL-6的影响及其机制研究

Effects of inhaled glucocorticoids on Foxp3^+ regulatory T cells and the expression of IL-2 and IL-6 in children with asthma

研究吸入丙酸氟替卡松(FP)对哮喘患儿外周血单个核细胞(PBMC)中CD4+Foxp3+调节T细胞、细胞因子IL-2、IL-6以及转录因子STAT5的影响。以30例确诊为支气管哮喘的患儿为研究对象,随机分为未治疗哮喘组(15例)、吸入FP缓解组(15例),10例同期正常儿童为对照组。流式细胞仪检测外周血PBMC中的CD4+Foxp3+调节T细胞比率,ELISA检测血浆或培养上清中IL-2、IL-6细胞因子水平,Western blot检测PBMC中磷酸化及非磷酸化STAT5的水平。结果1.未治疗哮喘组PBMC中CD4+Foxp3+T细胞百分率在PHA刺激培养前后均明显低于正常对照组,吸入FP缓解组明显升高,与正常对照组没有差异;各组刺激后CD4+Foxp3+T细胞百分率均有升高,吸入FP缓解组、正常对照组分别升高约1.89、2.01倍,而未治疗哮喘组升高仅1.56倍;2.未治疗哮喘组血浆中IL-6水平明显高于正常组及吸入FP缓解组,而IL-2水平没有明显差异;3.PHA刺激24 h后未治疗哮喘组磷酸化STAT5(p-STAT)表达水平明显低于吸入FP组及正常对照组,而各组STAT5表达水平没有明显差异,结论吸入FP能增加哮喘患儿外周血PBMC中CD4+Foxp3+调节T细胞数量,其机制可能与降低血浆IL-6,上调STAT5磷酸化水平有关。

To investigate the effect of fluticasone propionate(FP) on Foxp3+ regulatory T cells and the expression of IL-2 and IL-6,30 definitely diagnosed cases of children with asthma were selected for study and they were randomly divided into three groups,i.e.acute asthma with exacerbation(15 cases),asthma remitted by inhaled FP(15 cases) and children without history of allergic or atopic disorders(10 cases).The percentage of CD4+Foxp3+ T cells were detected by flow cytometry,while levels of IL-2 and IL-6 in blood plasma or supernatants of cell cultures were determined by ELISA.In addition,levels of phosphorylated and unphosphorylated STAT5 in PBMCs were analyzed by Western blotting.The experimental results showed that the percentages of CD4+Foxp3+ T cells in cases of asthma with exacerbation was significantly lower than that of the control children both before and after stimulation with PHA [(3.61%±0.69% vs 4.69%±0.32%,P<0.05)or(5.80%±0.86% vs 9.33%±0.17%,P<0.01)}.However,the percentage of CD4+Foxp3+ T cells in children with asthma remitted by inhaled FP was significantly higher than that of cases of asthma with exacerbation both before and after stimulation with PHA.All the cases selected for study showed a tendency to increase the percentage of CD4+Foxp3+ T cells,in which they increased up to 1.89 and 2.01 times respectively after stimulation with PHA for 24 hours in case remitted by FP and control children,but those of the untreated cases of children increased only to 1.56%.The level of IL-6 in blood plasma of children with asthma was higher than those of normal controls and cases remitted by FP,but no difference could be demonstrated in the level of IL-2;while the expression level of the phosphorylated STAT5(p-STAT5) 24 hours after stimulation in untreated cases was significantly lower than those of cases remitted by PF and normal controls,but there was no difference in the expression of STAT5 among various groups of cases.From these observations,it is evident that inhaled fluticasone propionate may effectively increase the percentage of CD4+Foxp3+ T cells in asthmatic children with exacerbation,which may be involved in the activation of STAT5 signaling pathway.