M4型毒蕈碱受体诱导COPD患者调节性T细胞分化的新机制

Abnormal regulatory T cells (Treg) in number and function have been described in COPD, but the underlying mechanism remains unclear. Muscarinic M4 receptors (M4R) are not only expressed in brain regions, but also in lymphocytes, and play a role in suppressing inflammation through Gi/o signaling pathway. Our previously published results showed for the first time that MR4 mRNA was increased in Treg while decreased in Th1/Th17; and the relative expression of M4R/M5R in COPD was lower than that in healthy subjects. In addition, the preliminary experiments showed that activation of M4R potentiated the differentiation of Treg when combined with TGF-β. To verify this hypothesis, we will detect the expression of M4R in peripheral blood CD4+T cells of COPD patients. Additionally, to certify the effect of M4R on proliferation/apoptosis/differentiation/suppression function of Treg, we will take advantage of M4R agonists/inhibitors, overexpression/interference of genes and signal antagonists. The future project will reveal the inherent relationship and signaling pathways between Treg and M4R, and finally provide a new target for the prevention and treatment of COPD.

慢阻肺存在调节性T细胞（Treg）数量与功能紊乱，机制不详。M4型毒蕈碱受体（M4R）不但分布于脑部各区域，而且在淋巴细胞上也有表达，通过Gi/o信号通路发挥抑炎作用。我们首次发表的成果指出：Treg主要表达M4R，Th1/Th17低表达M4R；COPD患者M4R/M5R比例较正常人表达降低。预实验表明，激动M4R受体能协同TGF-β促进Treg的分化。鉴此，我们推测M4R表达变化可以导致Treg的诱导分化异常，是COPD发病的重要机制之一。为此，我们将研究COPD外周血CD4+T细胞的M4R表达，并采用香烟提取物、M4R激动剂/抑制剂或基因过表达/干扰、信号分子拮抗剂等技术，研究M4R对Treg增殖凋亡、诱导分化和抑制功能的影响，揭示M4R和Treg的内在关系和信号通路，为防治COPD提供新靶点。

慢性阻塞性肺疾病(COPD)是一种涉及气道、肺实质和肺血管系统的慢性炎症性疾病，包括炎症反应的开启、进展和固化。COPD的发病机制一直存在一个谜团：炎症是如何开启以及炎症反应为何持续存在和持续加重。以T细胞为主的适应性免疫反应参与了COPD的发生和发展。通过我们一系列的研究，我们取得如下原创性成果：1、首次发现稳定期COPD患者外周血中CD4+CD25−Foxp3+ T细胞增高，外周和诱导性CD4+CD25−Foxp3+ T细胞表型上都属于激活的传统T细胞；2、揭示TGFβ1降低CD25表达和负责CD4+CD25+Foxp3+ T细胞转化分化为CD4+CD25−Foxp3+ T细胞的分子机制；3、诱导性CD4+CD25−Foxp3+ T 细胞降低幼稚CD4+ T细胞上CCR7和CD62L的表达，将幼稚T细胞的子代细胞转变为效应T细胞；4、CD4+CD25−Foxp3+ T 细胞展现出不稳定性和可塑性；5、首次提出记忆性CD4+CD25−Foxp3+ T细胞、幼稚CD4+ T细胞与Th17细胞正反馈回路是COPD慢性炎症持续化的机制；6、以CD25和Foxp3表达为基础的CD4+ T细胞作为潜在的外周标志物反应COPD的炎症活动度。综上所述，我们提出TGFβ1负责CD4+CD25+Foxp3+ T细胞分化为CD4+CD25−Foxp3+ T细胞；在促炎微环境下，具有记忆属性的CD4+CD25−Foxp3+ T细胞促进幼稚CD4+ T细胞增殖分化为Th17细胞，最终扩大和持续了COPD的慢性炎症反应。