清道夫受体SR-PSOX调节巨噬细胞的功能在类风湿关节炎发病中的作用和机制研究

Scavenger receptor that binds phosphatidylserine and oxidized lipids (SR-PSOX) is a kind of class G scavenger receptor. Our previous studies found that SR-PSOX and its ligand called oxidized low density lipoprotein (ox-LDL) were highly expressed in synovial tissue and serum from patients of rheumatoid arthritis (RA), respectively. These results implied that ox-LDL/SR-PSOX may paly an important role in the pathogenesis of RA. In this study, we will assess the role of SR-PSOX in the osteoclastogenesis, proliferation and activation of RAW264.7 via stimulation with ox-LDL. Further, we will analyse the effect of SR-PSOX on the function and polarization of macrophage through THP-1 cell, synovial monocytes and macrophages from RA patients. And make sure the possibly involved mechanism. Lastly, we will further verify the effect and mechanism of SR-PSOX mediated macrophage activation in the pathogenesis of RA by collagen induced arthritis (CIA) model which are constructed through induction of SR-PSOX transgenic and knockout mice. We believe our study will provide the novel perspective and theoretical basis for the pathogenesis of RA, and development of therapeutic strategy which targeted SR-PSOX.

SR-PSOX是一种G类清道夫受体，我们的前期研究发现SR-PSOX及其配体氧化低密度脂蛋白（ox-LDL）分别在类风湿关节炎（RA）患者滑膜组织和血清中高表达，提示ox-LDL/SR-PSOX可能在RA发病中发挥着重要作用。本研究拟通过ox-LDL刺激RAW264.7细胞，评估SR-PSOX在RAW264.7细胞增殖活化及参与破骨细胞发生过程中的作用；拟采用THP-1细胞及活动性RA患者来源的滑液单核/巨噬细胞，分析SR-PSOX对巨噬细胞功能和极化状态的影响并探讨可能参与的机制；并通过SR-PSOX转基因及基因敲除小鼠建立胶原诱导关节炎（CIA）模型，进一步验证SR-PSOX介导的巨噬细胞活化在RA发病过程中的作用和机制，为RA的致病机制和今后研发以SR-PSOX为靶向的治疗策略提供新的思路和理论依据。

CXCL16（又名SR-PSOX）既是一种穿膜型趋化因子又是一种G类清道夫受体，我们的前期研究发现CXCL16及其受体CXCR6在类风湿关节炎（RA）滑膜组织中高表达，同时发现RA患者血清中高表达SR-PSOX的配体氧化型低密度脂蛋白（oxLDL），提示CXCL16（SR-PSOX）及其配体可能在类风湿关节炎发病中发挥一定的作用。于是我们通过（1）比较RA患者及对照人群中oxLDL表达差异及其与临床指标相关性分析；（2）oxLDL对RA成纤维样滑膜细胞（RA-FLS）功能的影响；（3）oxLDL对RAW264.7细胞诱导破骨细胞分化的影响；（4）oxLDL对于THP-1细胞表达SR-PSOX的影响；（5）CXCL16对RA成纤维细胞分泌RANKL进而参与破骨细胞分化的影响；（6）Stattic对破骨细胞分化的影响，六个方面进行了探讨。结果发现RA患者血清中oxLDL表达增高，且与DAS28、CRP、ESR呈负相关，经治疗后oxLDL水平有所增加；对于RA-FLS细胞，oxLDL可明显促进细胞的增殖，且呈剂量依赖性的促进IL-6 mRNA的表达并抑制抑炎因子TGF-β mRNA的表达，其机制可能与上调SR-PSOX表达有关；对于RAW264.7细胞，oxLDL可促进细胞的增殖，oxLDL不具备单独或协同RANKL诱导破骨细胞生成的能力；TNF-α、IL-6和RANKL可下调RAW264.7细胞表面SR-PSOX的表达；对于THP-1细胞，oxLDL可促进THP-1细胞的增殖，同时可上调SR-PSOX的表达；RA滑膜组织及血清高表达CXCL16和RANKL，且血清CXCL16与RA疾病活动度呈正相关；细胞实验证实CXCL16可通过活化JAK2/STAT3和P38/MAPK通路刺激RA-FLS细胞分泌RANKL。STAT3抑制剂Stattic可显著抑制破骨细胞的生成。总之，CXCL16/CXCR6和oxLDL/SR-PSOX配体受体对均在类风湿关节炎致病过程中发挥一定的作用，此研究为进一步深入理解CXCL16（SR-PSOX）在RA发病中的作用以及开展靶向CXCL16（SR-PSOX）治疗RA的研究提供了理论基础。