从TL1A多态调控Th17分化角度研究SLE的发生及机制

Systemic lupus erythematosus (SLE) is a typical autoimmune disease with multiple organs and systems damage. Genetic factors and dysregulated immunity have been recognized to play important roles in the pathogenesis of SLE, but the mechanisms have not been clear elucidated. In our previous studies, expression of TL1A（tumor necrosis factor-like ligand 1A）was elevated in SLE patients and the rs4246905 polymorphism was significantly related to SLE, by which this polymorphism may functionally up-regulate the mRNA level of TL1A. In addition, available evidence suggested that Th17 performed significantly in SLE, and TL1A may regulate Th17 via the downstream signaling pathways. It is possible that polymorphism in TL1A gene may regulate the protein expression of TL1A, and therefore regulate the differentiation and function of Th17, playing an important role in the disease development of SLE. To clarify this hypothesis, the current study will firstly discuss the role of rs4246905 polymorphism in TL1A transcript, then will show the interaction of TL1A polymorphism and the downstream signaling pathways to elucidate the effect of polymorphism on Th17 differentiation, function and the molecular mechanisms. Finish of this project may give information about the mechanism of TL1A polymorphism in SLE development, and provide new target for individual treatment of SLE.

系统性红斑狼疮（SLE）是累及多系统、多器官的自身免疫病。遗传因素、免疫紊乱被认为在其发病中起重要作用，其机制尚不完全清楚。近期课题组发现SLE患者肿瘤坏死因子样配体1A（TL1A）表达异常，其rs4246905多态性与SLE相关，可能为功能性多态影响TL1A基因转录。国内外及课题组研究表明Th17参与SLE发病，且TL1A可能通过下游信号通路影响Th17。据此推测TL1A多态调控蛋白表达，进而影响Th17分化、功能并参与SLE发病。为证实此假设，本研究以rs4246905多态为切入点：（1）探讨该多态对TL1A基因转录功能的影响，以阐明此多态生物学功能；（2）研究此多态及其对Th17分化及功能影响，以明确其免疫学作用；（3）检测其下游重要信号通路变化，以阐明该多态影响Th17的分子机制。项目的完成将可能揭示TL1A多态通过何种机制参与SLE发生这一科学问题，为SLE个体化防治提供新靶点。

背景：系统性红斑狼疮（SLE）是一种累积多器官多系统的自身免疫病。近年来一直是免疫学家研究的热点课题。申请人前期在研究免疫细胞过度活化的机制及其参与SLE发病的作用时，发现SLE患者中Th17通路异常，而Th17已被证实参与了SLE的发生发展。因此，我们希望从研究T细胞的异常分化及相关机制入手，探索狼疮免疫过度活化的始动因素，并试图找到影响其过程的关键“靶分子”。近期申请人发现：SLE患者中CD4+TL1A+T细胞表达、血浆TL1A表达异常，且与疾病活动指数SLEDAI、Th17相关因子的表达相关；过表达293T细胞中TL1A基因后Th17相关转录因子RORγt表达升高；相反，沉默TL1A基因后RORγt表达降低；分析TL1A基因多个功能区域与SLE遗传关联，发现rs6478109与SLE遗传易感相关。基于此推测，TL1A rs6478109多态可能调控其表达，进而影响Th17分化、功能并导致SLE的病理过程。.主要内容：（1）构建rs6478109点突变质粒，探讨该多态性对TL1A基因启动子区转录活性;（2）沉默/过表达TL1A基因，检测TL1A对Th17细胞分化的影响；（3）探讨TL1A通过下游重要信号分子NF-κB、MAPK影响Th17的分子机制。.重要结果/关键数据：（1）TL1A基因rs6478109多态性与SLE遗传易感相关，该位点碱基突变可以上调荧光素酶活性，使TL1A基因启动子区活性增强；（2）过表达TL1A上调RORγt及IL-17表达、促进Th17分化，而沉默TL1A后下调RORγt及IL-17表达；（3）TL1A刺激细胞后上调p38信号通路、RORγt及IL-17的表达水平；而p38信号通路抑制剂处理后，TL1A刺激诱导的RORγt及IL-17的表达水平被抑制。.科学意义：靶向SLE中异常表达的TL1A，可能能够抑制疾病的发生发展，这一作用可能与TL1A表达/功能失衡，进而通过p38信号通路导致Th17紊乱，参与疾病的发生发展有关。因此，在今后的研究中，研发TL1A靶向结合药物，可能能够改善狼疮病情。本研究为今后寻找新的靶向药物治疗SLE，如靶向TL1A，提供前期理论依据；同时也从基础研究角度揭示了存在多态性的TL1A基因可以使参与SLE发病的Th17异常。