miR-26a在全身型幼年特发性关节炎中的作用和分子机制研究

The abnormal expression of inflammatory cytokines induced by innate immune dysfunction plays a crucial role in the pathogenesis of systemic juvenile idiopathic arthritis (sJIA), but the molecular mechanism is still not clear. The emergence of microRNA provides totally new perspective to explore the pathogenesis of sJIA. We have found that the expression level of miR-26a is exclusively elevated in plasma from sJIA patients as compared with healthy and disease controls. Bioinformatic analysis and preliminary experimental results indicated that TRAF3, an important adaptor protein in innate immune signaling pathway, is a potential target of miR-26a. Based on above, we propose the hypothesis that miR-26a fine tunes TRAF3 to modulate immuno-inflammatory response in sJIA. We will use the methods of Real-time quantitative PCR, luciferase reporter assay and RNAi silence etc. to study the relationship between abnormal expression of miR-26a and the pathogenesis of sJIA，elucidate the effect and mechanism of miR-26a targeting immune molecule in sJIA at molecular, cellular and animal levels. Furthermore, we will explore how miR-26a is regulated by cytokines, consequently forming a feedback loop centered on miR-26a. This project will firstly elaborate the mechanism of miRNA in the immuno-inflammatory response of sJIA. The results will contribute to understand the pathogenesis of sJIA in depth and provide new treatment targets of sJIA.

固有免疫调控异常导致炎性细胞因子表达紊乱在全身型幼年特发性关节炎（sJIA）发病过程中起关键作用，但调控的分子机制尚不清楚。microRNA的发现为认识该疾病的发病机理提供了全新视角。我们研究发现miR-26a在sJIA患儿血浆中特异性上调表达，并初步验证了固有免疫信号通路中重要的接头分子TRAF3是其作用靶点。据此我们提出假说，miR-26a靶向TRAF3影响sJIA发病。我们拟采用实时荧光定量PCR、荧光素酶报告基因实验、RNA干扰等方法，从分子、细胞至动物水平研究miR-26a的异常表达与sJIA发病的关系，阐释miR-26a通过免疫分子如何影响sJIA免疫炎症反应，并进一步探索调控miR-26a表达水平的分子机制。本项目将以miR-26a为切入点，首次阐述miRNA在sJIA免疫炎症过程中的作用机理，有助于从新的层面理解sJIA的发病机制，也将为sJIA的治疗提供新靶点。

幼年特发性关节炎（JIA）是致残率很高的儿童自身免疫性疾病，因其是除外性诊断，目前仍缺乏特异性生物标志物以应对早期诊断确证和预后评估。其中，全身型幼年特发性关节炎（sJIA）是一种严重的慢性自身炎症性疾病，近期大量研究表明细胞因子风暴是引起sJIA系统炎症反应，局部关节损伤和骨侵蚀的重要原因，但调控的分子机制并不清楚。microRNA的发现为认识该疾病的发病机理提供了全新视角。本项目基于前期工作中JIA患儿miRNA芯片筛查结果，证实miR-26a在sJIA血浆以及外周血单个核细胞（PBMCs）中特异性上调表达；发现在多关节型JIA（poly-JIA）中miR-766特异性表达并具有临床鉴别诊断价值。体外高表达细胞实验证明，miR-26a可显著抑制促炎细胞因子表达；同时发现抗炎细胞因子IL-37也能够抑制sJIA患儿PBMCs中促炎细胞因子IL-6，TNF-α和IL-17的mRNA和蛋白水平，表明促炎-抗炎细胞因子平衡在sJIA的发病过程中可能发挥重要作用。证实miR-26a在炎症信号通路中的作用靶点为TAK1而非先前预测的TRAF3，并进一步验证了miR-26a靶向TAK1抑制炎症因子TNFα介导的NF-κB的活化，从分子和细胞水平探究了miR-26a参与炎症反应的分子机制。sJIA样小鼠模型正在构建中，完成后将会完善相关机制在小鼠模型中的验证。本研究证实了miRNAs具有作为JIA疾病特征生物标志物的潜力，从miRNAs和抗炎细胞因子等新的层面阐述了sJIA的发病机制。为临床上有效预防、治疗sJIA提供了新的思路和干预靶点。