基于TREM-1探讨芍药苷干预TLR信号通路在类风湿关节炎的抗炎作用

Macrophages play a pivotal role in the regulation of immune system, which modulating immune response and immune tolerance, and the over-activated macrophages are closely related to the pathogenesis of rheumatoid arthritis (RA). Recently, triggering receptor expressed on myeloid cell-1 (TREM-1) was identified as an stimulating receptor which can amplify inflammatory response by priming and synergizing toll-like receptor (TLR) signal pathway and subsequently promote the excessive activation of macrophages. TREM-1 has close relationship with chronic synovitis so that it is expected as a promising novel target of treatment for RA. Our preliminary experiments have demonstrated that paeoniflorin (PF) could down-regulate the expression of TREM-1 in macrophages, and the over-expression of TREM-1 can reverse the expression of IRF5 an pro-inflammatory cytokines mediated by PF inhibition. Thus we come to the hypothesis that PF could downregulate the expression of TREM-1 and interfere with TLR/IRF5 signaling pathway, which result in the suppression of inflammation in RA. Base on our previous work, this study was designed to investigate the molecular mechanism of PF-mediated inhibition of TREM-1 expression, and to investigate the ability of PF on macrophage activation and differentiation and the ability of PF-treated macrophages on inducing CD4+T cell polarization in vitro. The study will also evaluate the efficacy of PF-treated macrophages in the treatment of RA animal models, which may provide supportive molecular biological evidence for PF, as an Chinese traditional medication, in the treatment of RA.

巨噬细胞是机体的免疫调节中枢，调节免疫应答和免疫耐受，其过度活化是类风湿关节炎(RA)发病的中心环节。而髓样细胞诱发受体（TREM-1）是新近发现的能促发和协同TLR信号放大炎症的激活受体，促进巨噬细胞过度活化，与滑膜组织慢性炎症密切相关，有望成为RA抗炎药物的作用靶点。我们预实验发现芍药苷（PF）下调巨噬细胞TREM-1和IRF5的表达，过表达TREM-1能逆转PF抑制的IRF5和促炎因子的表达。由此我们提出"PF下调TREM-1表达，干扰TLR/IRF5信号转导通路，抑制RA炎症"的假说。在前期工作基础上，本课题拟深入探讨PF抑制TREM-1表达的分子机制；以TREM-1为切入点，研究PF对巨噬细胞的活化和分化作用及PF干预后巨噬细胞在体外诱导CD4+T细胞极化的能力；并评价PF干预后巨噬细胞对RA动物模型的治疗作用；为阐明PF治疗RA的分子基础和RA的中医药治疗提供现代科学的支持。

单核/巨噬细胞是机体的免疫调节中枢，调节免疫应答和免疫耐受，其过度活化是类风湿关节炎(RA)发病的中心环节。而髓样细胞诱发受体（TREM-1）是新近发现的能促发和协同TLR信号放大炎症的激活受体，促进单核/巨噬细胞过度活化，与滑膜组织慢性炎症密切相关，有望成为RA抗炎药物的作用靶点。. 前期临床工作发现，白芍治疗RA有显著疗效且毒副作用较低，但机制不明，而芍药苷（PF）是白芍的主要有效成分，我们预实验发现PF下调CD14+单核细胞TREM-1表达。在此前期工作基础上，本研究利用细胞模型，以TREM-1为切入点，研究PF对单核细胞的活化和分化作用及PF干预后单核细胞在体外诱导CD4+T细胞分化的能力，并评价PF干预后单核细胞对RA动物模型的治疗作用。. 我们发现PF呈浓度依赖性下调RA患者CD14+单核细胞TREM-1的mRNA及蛋白表达；PF通过下调TREM-1表达抑制PGN,LPS激活的RA患者单核细胞促炎因子生成并进而抑制Th1细胞分化；RA患者滑膜组织和单核细胞高表达IRF5，TLR配体刺激剂进一步促进单核细胞IRF5表达；PF抑制RA患者单核细胞IRF5表达，进一步过表达TREM-1能逆转下调的IRF5表达。我们进而建立CIA鼠模型，证实了 PF通过抑制TREM-1表达，进一步抑制单核细胞促炎因子的分泌和Th1细胞的分化从而减轻CIA鼠炎症。. 所得结果对于了解PF免疫抑制作用的机制及其临床应用提供了实验依据，同时也对以PF下调TREM-1表达干扰TLR/IRF5信号转导通路抑制RA炎症的免疫干预手段提供理论基础。