NFIL3调控NLRP3炎症小体的机制及作为类风湿关节炎临床标志物研究

Rheumatoid arthritis (RA) is a systemic autoimmune disease of unknown etiology that characterized by progressive destruction of peripheral joints and persistent chronic inflammation of synovial tissue. Recent studies demonstrated that aberrant activation of NLRP3 inflammasome is closely related to the development of rheumatoid arthritis. Our previous research found that the expression of nuclear factor interleukin-3-regulated protein (NFIL3) was significantly decreased in RA synovial tissue, and negatively correlated with NLRP3. It has been reported that CD39 promote the hydrolysis of ATP to suppress the activation of NLRP3. Based on transcription factor binding profile database, we found CD39 might be the downstream signal molecule of NFIL3. Thus, we raised the hypothesis that NFIL3-mediated histone modification can induce the expression of CD39, reduce extracellular levels of ATP, then inhibit NLRP3 inflammasome activation. We use cell lines, tissue and mouse models to demonstrate the potential pathway of NFIL3-mediated inflammasome activity aggravate arthritis, further elucidate the molecular mechanism of NFIL3 inhibit the NLRP3 inflammasome by inducing CD39. Finally, we evaluate the value of NFIL3 as a biomarker for RA disease activity with clinical samples. In this study, we aimed to find out novel biomarkers to monitor RA progress, and provide the basis for seeking new therapeutic targets.

类风湿关节炎（RA）是一种病因不明的自身免疫性疾病，以关节、滑膜慢性炎症为主。近年研究显示，NLRP3炎症小体异常活化与RA发生发展密切相关，明确其上游调节分子将为RA治疗提供新靶点。我们前期研究发现，核因子白介素3调节蛋白（NFIL3）在RA患者滑膜组织中表达显著降低，与NLRP3呈强负相关。研究表明CD39通过水解ATP抑制NLRP3活化，转录因子结合数据库预测CD39可能是NFIL3下游调控分子，因此我们提出NFIL3通过组蛋白修饰促进CD39表达，下调细胞外ATP浓度，抑制NLRP3炎症小体过度活化的假说。本研究拟从细胞、组织和动物水平明确NFIL3表达紊乱致炎症小体异常活化加重关节炎症作用途径；进一步从分子水平阐明NFIL3介导CD39抑制NLRP3的分子机制；临床标本分析NFIL3作为RA疾病严重程度标志物的应用价值。旨在为RA疾病监测提供新的标志物，为寻找新治疗靶点提供依据。

NLRP3炎症小体异常活化与RA发生发展密切相关。近期，研究报道了一对患有幼年特发性关节炎的双胞胎，通过全外显子测序发现其均在NFIL3基因上存在纯合突变，通过体内外研究发现NFIL3的表达与NLRP3炎症小体活化密切相关。NFIL3作为转录因子在免疫调节及自身免疫性疾病中发挥重要作用。但是，外周血NFIL3表达与RA的关系尚不明确。我们通过qPCR检测初诊RA患者及健康人群外周血NFIL3转录水平，发现RA患者NFIL3表达显著升高，且与ESR、抗CCP抗体呈正相关，但与DAS28无显著相关性；分析治疗前、后NFIL3表达情况，结果显示NFIL3转录水平显著下调。通过流式细胞术首次绘制了RA患者外周血Th17和Treg细胞亚群上NFIL3的表达情况，结果显示RA患者NFIL3表达比例显著上升，NFIL3在各亚群中表达比例较高，提示NFIL3可能参与T细胞亚群的分化。通过THP-1源性巨噬细胞，我们发现NLRP3炎症小体活化受furin蛋白表达调控，抑制furin可激活炎症小体。本研究有助于深入探讨NFIL3、NLRP3炎症小体活化与RA发病机制的关系，为提供RA新的疾病监测标志物及治疗靶点奠定研究基础。