Ets-1调控Foxp3甲基化及STAT通路诱导Treg/Th17失衡参与RA疾病发生发展的机制研究

Treg/Th17 imbalance has been reported involved in kinds of diseases. The exact mechanism of Treg/Th17 imbalance now has drawn much attention. We have previously demonstrated Treg/Th17 skewing in RA patients. In present study, we aim to explore the regulatory factor associated with Treg/Th17 imbalance in RA patients. Ets-1, a transcription factor, is published to participate in Treg and Th17 regulation. Ets-1 could bind to the demethylated Foxp3 gene and contribute to the stabilization of Foxp3 expression in regulatory T cells. Ets-1 is also reported as a negative regulator of Th17 differentiation. Ets-1 could constrain Th17 cell generation via Jak-Stat pathway. Combined our previous results and the latest published findings, we aim to investigate the expression of Ets-1 in Treg and Th17, Foxp3 methylation condition, STAT5 and STAT3 expression in RA patients. For the first time, we study the regulatory role of Ets-1 on Treg/Th17 balance in clinical disease, and hope to elucidate the exact mechanism that Ets-1 induces Treg/Th17 skewing via regulating methylation of Foxp3 gene and STAT5/STAT3 in RA patients.

本课题组前期的研究已经证实Treg/Th17失衡参与介导了RA患者的免疫紊乱、关节炎症和骨质破坏。新近的研究证实，Treg和Th17细胞都受到转录因子Ets-1的调控。Ets-1能够参与Foxp3基因的甲基化调控进而调节Treg的分化和功能发挥；Ets-1能调节STAT通路从而参与调节Th17细胞的分化。本课题首次将Ets-1、Treg和Th17细胞结合起来，研究RA患者Ets-1表达异常介导Treg/Th17失衡的调控机制，通过体内表达分析和体外细胞实验验证，阐明RA患者Ets-1的异常表达通过参与Foxp3甲基化调控和STAT通路调节，进而参与诱导Treg/Th17失衡的具体机制，同时根据DAS28评分判断RA患者疾病活动度，阐明Ets-1表达、Foxp3甲基化、STAT通路、Treg/Th17失衡与RA疾病活动度的关系，为RA疾病发病机制的研究和治疗靶点的选择提供新思路。

本课题重点关注了Ets-1在RA疾病发生发展中的作用，研究结果显示ETS-1 rs73013527位点与RA疾病易感性相关，该位点等位基因T是RA疾病患病的保护性因素，但是对于已患病人群来说，却与RA疾病活动的严重程度相关。而携带rs4937333、rs11221332、rs73013527位点单体型CCT或者TCT的人群RA疾病的患病风险降低。另一方面，RA疾病临床病例样本的检测和细胞功能实验的结果显示：RA患者CD4+T细胞中Ets-1表达降低，Foxp3基因TSDR区域甲基化程度增高，Foxp3表达降低；RA患者同时还存在CD4+T细胞中STAT3和STAT5降低而STAT3/STAT5比值升高，ROR-γt表达增加、IL-17血浆水平升高。本课题的研究显示：ETS-1基因多态性与RA疾病易感相关；RA患者CD4+T细胞中Ets-1表达降低，诱导了Foxp3基因甲基化程度增高、Foxp3表达下降从而介导了CD4+CD25+Foxp3+调节性T细胞的表达降低；Ets-1的表达降低，同时还诱导了STAT3/STAT5通路异常，以STAT5表达下降为主要表现，介导了RA患者CD4+T细胞中Foxp3表达下降而IL-17合成分泌增加，RA患者出现Th17/Treg失调，表现为CD4+CD25+Foxp3+调节性T细胞表达降低而Th17细胞表达增加并高分泌IL-17。基于本课题的研究结果，我们将进一步关注RA患者免疫紊乱的重要调控因子，为临床阐明RA疾病的发病机制和治疗靶点选择打下基础。