TSHR易感位点导致Graves病人群TRAb持续阳性的机制探讨

Graves’ disease (GD) is a common autoimmune disease with a prevalence of 1-2% in the Chinese population and is characterized by presentation with thyroid stimulating hormone receptor (TSHR) autoantibodies (TRAbs), which leading to overproduction of thyroid hormone and the characteristic metabolic abnormal in multiple organs and tissues. It is suggested that TRAb positivity was the barometer of GD relapse. The GD patients with persistently positive TRAb were easy to relapse after drugs withdraw. In our previous study, convincing evidences have been provided not only for the association of TSHR region with GD, but for that with TRAb persistently positive after the GD patients treated by drugs over one year. Then we confirmed rs179243 and rs12101261 were the major independent susceptibility loci associated with GD, and highly correlated with the GD population with TRAb persistently positive. The mechanisms that account for the susceptibility and recurrence of individuals carried the susceptibility loci of TSHR to GD are poorly understood, and that’s going to be our research focus. In this study, we will further investigate patients with TSHR GD susceptibility loci have higher occurrence of hyperthyroidism, and the serum TRAb persistently positive after antithyroid drug therapy, by molecular biology, animal experiments and clinical study. Our project will provide the valuable experimental basis and theory foundation for predicting the occurrence and prognosis of GD and searching the targeted gene therapy for GD.

Graves病（GD）是常见的自身免疫性疾病，中国人群患病率约1-2%，其重要病理特征是促甲状腺激素受体（TSHR）抗体（TRAb）产生，引起甲状腺激素生成过多而发生多器官组织代谢紊乱。已知TRAb是GD临床转归的重要预测指标，TRAb持续阳性的GD患者停药后易复发。我们前期研究证实TSHR不仅是GD重要致病易感基因，且与药物治疗一年以上GD患者TRAb持续阳性相关。继而我们发现rs12101261及rs179243是GD在TSHR区段独立易感位点，与GD人群TRAb持续阳性高度相关。TSHR易感位点通过何种机制导致GD易感及复发成为关注重点。本课题拟通过分子生物学、动物实验及临床研究探讨TSHR的GD易感基因位点如何促进甲亢的易感性发生，且为什么抗甲状腺药物治疗后携带有易感基因位点的GD患者TRAb不易转阴。这将为运用基因预测GD发生、预后及找寻治疗GD靶基因提供实验依据和理论基础。

目的: 探讨Graves病促甲状腺激素受体（TSHR）易感位点导致促甲状腺激素受体抗体（TRAb）持续阳性的机制及随访研究 .方法: 1300例Graves病患者外周血抽提DNA并通过荧光探针行Graves病TSHR易感位点rs179243, rs179247, rs12101261, rs2284722, rs2300525, rs4903964, rs7158936, rs12050151,rs2284720基因分型, 正规抗甲亢治疗随访1年后检测血TRAb浓度，分析TSHR易感位点与TRAb滴度之间的关系；同时收集了45例甲状腺手术病人肿瘤旁正常的甲状腺组织并进行rs179243，rs179247，rs12101261，rs2300525基因分型及通过实时定量PCR对TSHR截短型转录本ST4，ST5表达进行鉴定和分析。 .结果: Graves病TSHR易感位点rs179243, rs179247, rs12101261, rs2284722, rs2300525, rs4903964, rs7158936, rs12050151, rs2284720的易感基因型与TRAb阳性存在显著的相关性, 但rs3783949与rs17111394与TRAb阳性不存在显著的相关性。同时二元logistic逐步回归分析显示rs179243, rs179247及rs2300525易感位点是TRAb持续阳性的独立影响因素，且三种SNP易感基因型（TT/AA/GG）的组合明显提高了Graves病患者TRAb持续阳性的风险（OR=3.486,P =0.005）。易感基因型rs179243，rs179247，rs12101261提高TSHR截短型转录本ST4，ST5表达水平。 .结论: Graves病TSHR易感位点可能通过增加TSHR截短型转录本ST4，ST5表达水平导致TRAb持续阳性。