Let-7a在哮喘T淋巴细胞失衡中的作用研究

目的:探讨let-7a在哮喘中的表达水平及调节T淋巴细胞亚群失衡的功能作用。方法:收集39例哮喘患者及19例非哮喘对照,Real-time PCR检测let-7a的表达。从哮喘患者外周血单核细胞(Peripheral blood mononuclear cell,PBMC)中分选Th1,Th2和Th17细胞,检测let-7a在T淋巴细胞亚群中的表达。磁珠分选naive T细胞,分别诱导分化成Th1、Th2和Th17细胞,分析let-7a在T淋巴细胞亚群中的表达。Let-7a mimic分别转染Th2和Th17细胞,ELISA检测IL-13和IL-17的表达。结果:与对照组比较,let-7a在哮喘患者肺组织和血清中低表达,并随着哮喘病程进展,let-7a的表达水平也越低。哮喘患者来源的CD4~+T细胞中,let-7a表达明显低于非哮喘对照组。Let-7a在哮喘来源和体外刺激分化的哮喘炎性Th2和Th17细胞中的表达明显下调,而在Th1细胞中的表达没有变化。Let-7a mimic改变了Th2和Th17相关细胞因子IL-13和IL-17的表达。结论:Let-7a在哮喘中低表达,调节哮喘T淋巴细胞亚群失衡,改变了Th2和Th17细胞的功能,是哮喘理想的诊断和治疗靶点。

The Function of Let-7a in the Imbalance of T Cell in Asthma

ABSTRACT Objective: To analyze let-7a expression in patients with asthma and explore the bio-function of let-7a on the imbalance of T cell subsets in asthma. Methods: 39 patients with asthma and 19 non-asthma control were recruited in this research. The expression of let-7a was analyzed using Real-time PCR. The naive T cells were separated with magnetic beads, and then differentiated into Th1, Th2 and Th17 cells under cytokines stimulation in vitro, respectively. IL-13 and IL-17 were further detected with ELISA after let-7a mimic was transfected into Th2 and Th17 cells. Results: Compared with control group, let-7a was down-regulated in lung tissue and serum in patients with asthma. At the same time, the expression of let-7a was decreased with the development of asthma progression. Furthermore, let-7a expression was decreased in CD4⁺T cells in patients with asthma than that in control group. Interestingly, let-7a was significantly down-regulated in Th2 and Th17 cells from either patients with asthma or the differentiation in vitro, whereas let-7a expression had no significant change in Th1 cells. Let-7a inhibited IL-13 secretion in Th2 and IL-17 in Th17 cells, respectively, indicating that let-7a had an important role on the function of Th2 and Th17 cells. Conclusion: Down-expressing let-7a in asthma regulated the imbalance of T cell subsets and altered the function of Th2 and Th17 cells. Thus, let-7a may be an ideal bio-marker for asthma diagnosis and therapy.