雷公藤甲素促进调节性T细胞诱导和维持Foxp3表达的机制研究

Regulatory T cells (Treg) are a subpopulation of CD4+T cells that have been described in recent years to possess hyporesponsive and suppressive capacities. These cells are generated in the thymus (nTreg) and in the periphery (iTreg)﹐have indispensable roles in immunological tolerance and protecting from autoimmune diseases. Foxp3 is specifically expressed in Treg and plays a critical role in the differentiation﹐maintenance and effector functions of Treg﹐the transcription of Foxp3 is regulated by complex mechanisms including signaling pathway and epigenetic control. Compelling evidence suggests that Treg can generated de novo in a TGF-β-dependent process from CD4+CD25-T cells. However﹐Foxp3 expression in these induced cells is unstable in vitro and in vivo, therefore﹐it is very important to look for the drug that can maintain Foxp3 expression. Triptolide purified from a Chinese herb Tripterygium wilifordii Hook F possess the immunosuppressive effects and plays the role in success treatment of some autoimmune disease. Our recently data reveals that Triptolide promotes the induction and expression of Foxp3﹐nonetheless, underlining mechanism(s) remain still unclear. In the present study, we will investigate the effects of Triptolide in the Foxp3 induction and maintenance using the immunological methods including real-time PCR﹑flow cytometry、western blot analysis and chromatin immuno-precipition. This study will elucidate the mechanism of Triptolide in promoting induction and maintaining expression of Foxp3 in CD4+CD25-T cells by TGF-β﹐eventually providing a fundamental theory basic for the clinical treatment of Triptolide.

调节性T细胞（Treg）是一群具有免疫抑制和免疫无能的CD4+T细胞亚群，按来源可分为外周诱导的Treg（iTreg）和胸腺来源的Treg（nTreg）。iTreg具有数量可控和抗原特异性的优点，是目前Treg治疗自身免疫性疾病的首选和希望。Foxp3是Treg的特异性标记物，也是决定Treg的分化和功能的重要基因，Foxp3基因受到多个水平的调控。现已明确Foxp3能由TGF-β诱导产生，但其在体内外不能持续和稳定的表达，因此寻找一种能维持其表达的药物显得非常重要。雷公藤甲素作为治疗自身免疫性疾病的常见中药之一，我们的预实验结果显示其能诱导和稳定Foxp3的表达，但机制尚不明确。本研究采用流式细胞术、实时荧光定量PCR、染色质免疫沉淀、Western-blot等方法，从信号通路、转录因子和表观遗传机制来阐明雷公藤甲素诱导和维持Foxp3稳定表达的分子机制，从而为其临床治疗提供理论的基础。

本研究采用流式、Western-blot、RT-PCR等免疫学方法来观察雷公藤甲素对调节性T细胞的分化和在炎症状态下维持Foxp3表达的影响，我们发现：(1)雷公藤甲素能促进TGF-β诱导CD4+iTreg的能力，与TGF-β信号通路有关；（2）雷公藤甲素能减轻狼疮性肾炎小鼠的临床和病理，与其促进Treg的体内诱导和抑制Th17细胞分化有关；（3）雷公藤甲素维持炎症状态下Treg的Foxp3稳定表达；（4）组蛋白甲基转移酶EZH2可能介导雷公藤甲素促进Treg的诱导。本项目的研究成果为临床使用雷公藤甲素治疗自身免疫病奠定理论基础。