自噬在实验性性关节炎中的分子机制研究

Our previous study has found that enhanced autophagy occurred in pristane-induced arthritis (PIA) model. Accordingly, we propose to further investigate the role and mechanism of autophagy in experimental arthritis. First, we will demonstrate the autophagy phenomenon by electron microscope observation, LC3 convention detection in PIA and collagen-induced arthritis models and pristane stimulated macrophage and synovial fibroblast cell models, and confirm the role of autophagy on arthritis via autophagy pathway intervention by specific inhibitors and RNAi in vivo and in vitro. Second, the changes of endoplasmic reticulum stress, oxidative stress, mTOR and AMPK signaling, which are considered as potential triggers of autophagy, will be detected in the cell models. And the individual pathway will be blocked and the effect of autophagy will be evaluated to screen the key pathway for autophagy induction. Moreover, the relationship between autophagy and TLR3 which has been found to play crucial roles in PIA in our previous work will be illustrated by using autophagy related gene knockdown cells and TLR3-deficient cells. In addition, we will analyze whether autophagy could upregulate TLR3 expression via its specific transcription factor and lead to inflammation subsequently by promoter reporter gene assay and ChIP, and further identify the downstream pathway of autophagy. Finally, this project will provide the significant theoretical basis for the research of rheumatoid arthritis pathogenesis, and offer new targets for the medicine research and development.

我们发现在降植烷诱导的关节炎（PIA）模型中自噬水平显著升高，因此拟进一步探讨自噬在实验性关节炎中的作用和分子机制。首先在PIA和胶原诱导的关节炎模型、pristane刺激的巨噬细胞模型和滑膜成纤维细胞模型中，进行电镜观察和LC3蛋白转化检测确认自噬增强现象，并通过抑制剂和RNAi在体和体外干预自噬通路，分析其在关节炎中的作用；进而在细胞模型中观察可能影响自噬发生的内质网应激、氧化应激、mTOR和AMPK通路的改变，并在阻断各通路后观察对自噬的影响作用以确定主要调控通路；之后采用自噬基因敲低和TLR3敲除细胞，明晰自噬与我们发现的在PIA中具有关键作用的TLR3之间的关系，再利用启动子报告基因、ChIP等技术，分析自噬是否通过TLR3特异性转录因子上调其表达而导致炎症发生，以明确自噬发挥作用的下游通路。研究结果将为类风湿关节炎的发病机制研究提供重要的理论基础，并为其药物研发提供新的靶点。

我们发现在pristane诱导的关节炎（PIA）模型中自噬水平显著升高，因此项目组进一步探讨了自噬在实验性关节炎中的作用和分子机制。首先在PIA诱导的关节炎模型、pristane刺激的巨噬细胞模型中，进行电镜观察、LC3和Becn1 mRNA水平检测及LC3蛋白转化检测，确认了pristane导致的巨噬细胞自噬增强现象，并通过抑制剂和RNAi在体和体外干预自噬通路，证实了抑制自噬可减轻实验性关节炎的症状。进而项目组在细胞模型中观察了影响自噬发生的内质网应激、氧化应激、mTOR和AMPK通路的改变，发现内质网应激增强及mTOR表达降低介导了pristane对巨噬细胞自噬增强的效应。并进一步采用内质网应激的激动剂/抑制剂证实了这一结果。同时对mTOR的泛素化的检测证实其表达降低的可能原因是降解增多。对于自噬的下游作用主要集中在它对TLR3的表达调控上，因为实验结果显示无论是在PIA模型的脾脏中还是巨噬细胞模型中，TLR3的表达与自噬具有正相关性。项目组采用自噬基因敲低和TLR3敲除细胞，明确了自噬可对TLR3具有显著调控作用，进而利用启动子报告基因、ChIP等技术，发现自噬可通过STAT1-IRF1通路调控TLR3表达，从而介导关节炎症发生。除此之外，miRNA26a也可以靶向调节TLR3的表达参与PIA的发生发展。这些研究结果将为类风湿关节炎的发病机制研究提供重要的理论基础，并为其药物研发提供新的靶点。