IL33/IL1RL1基因通路在白塞病发病机制中的作用研究

Behçet's disease (BD) is a multi-factorial (autoimmunity, genetics, etc.), chronic and, relapsing, multisystemic inflammatory disorder. IL33/ST2, a newly discovered pathway believed to play a crucial role in immunoregulation, was reported to be associated with pathogenesis of rheumatoid arthritis and inflammatory bowel disease. Our previous studies revealed that serum ST2 increases significantly in BD uveitis patients and polymorphisms of its coding gene (IL1RL1) are associated with BD susceptibility (783 BD patients VS 701 healthy controls). In this study, we plan to fine-map BD associated single nucleotide polymorphisms (SNPs) in IL33/IL1RL1 (coding IL33/ST2) gene regions by MassArray iPLEX technique, to analyze their correlations to phenotypes of BD, and to further evaluate their roles on expression of IL-33/ST2 and associated mechanisms (such as their influences on the binding capacity of transcription factors and microRNAs). Our study aims to shed more light on the pathogenesis of BD and to identify potentially novel targets for treatment.

白塞病（Behcet's disease，BD）是自身免疫及遗传等多因素致病、多系统受累的慢性炎性疾病。IL33/ST2通路是近年新发现的免疫调节信号通路，文献报道该通路在类风湿性关节炎、炎性肠病等疾病的发病中起重要作用。我们的前期研究发现BD葡萄膜炎患者血清中分泌型ST2显著升高，且其编码基因IL1RL1多态性与BD易感性相关（783例BD患者 VS 701例健康对照）。本项目拟应用MassArray iPLEX技术精细定位并鉴定IL33/IL1RL1基因（编码IL33/ST2）区域与BD相关的SNP并分析其与BD临床表现的相关性；进一步应用荧光素酶报告基因等技术研究相关SNP的功能，包括对转录因子结合能力及IL33/ST2表达水平的影响等，旨在进一步阐明BD的发病机制以及寻找新的治疗靶点。

白塞病葡萄膜炎（Behcet’s disease uveitis，BDU）是我国最常见的致盲性葡萄膜炎之一。尽管目前已达成共识，认为BDU的发生及发展与遗传、免疫等多种因素相关，然而该病的具体发病机制尚不明确。前期研究发现，白介素（interleukin，IL）家族新成员——IL-33及其受体生长刺激表达基因2蛋白（growth suppression of tumorigenicity 2，ST2）可能在BDU发病中发挥重要作用，但IL-33/ST2通路在分子免疫学层面发挥的具体调控机制尚不清楚。因此，本项目研究了IL33/IL1RL1基因通路单核苷酸多态性（single nucleotide polymorphism，SNP）对基因转录、翻译过程的影响，及其在BDU发病机制中的作用。主要研究内容及成果如下：（1）筛选IL33/IL1RL1基因区域内与BDU相关的SNP位点，发现IL1RL1基因rs3821204位点G等位基因、rs12712142位点A等位基因与BDU发病相关，IL33基因区域SNPrs2210463、rs7044343和rs1048274与BD亚型相关；（2）筛选上述SNP位置及潜在功能，预测得出位于IL33/IL1RL1基因区域3’非翻译区的SNPrs3821204和rs12712142可分别与微小RNA（microRNA，miRNA）hsa-miR-548m和hsa-miR-892a结合；（3）研究SNP改变对miRNA结合能力及基因表达的影响，发现SNPrs12712142位点突变可减弱其与hsa-miR-892a的结合能力，改变IL1RL1的表达活性，从而影响BDU的发生；（4）检测SNP对IL-33和ST2蛋白表达的影响，发现BDU患者血清sST2水平显著升高，IL-33水平轻度升高；作为对照的Vogt-小柳原田病（Vogt-Koyanagi-Harada disease，VKH）患者血清IL-33和sST2水平均显著升高，且与疾病活动性相关；（5）完成项目计划研究内容后，我们还对BDU和VKH患者的光学相干断层扫描血管成像特点进行了研究，并对难治性BDU的治疗方法进行了回顾性及前瞻性研究。综上，本项目的基础研究结果提示IL33/IL1RL1基因通路在BDU发病中发挥保护作用，临床研究则为BDU临床诊断、随访和治疗提供了新思路。