低氧诱导因子在类风湿关节炎发病机制中的作用

类风湿关节炎（rheumatoid arthritis，RA）是一种系统性自身免疫性疾病，病理特征为异常的滑膜增生伴血管翳形成、软骨和骨的侵蚀破坏，最终导致关节畸形。目前RA确切发病机制未明，环境和遗传因素相互作用共同促进了RA的发病。低氧微环境是RA重要的病理特点，炎症滑膜组织的高代谢需求和滑膜的快速增生共同导致了RA关节内低氧状态。研究表明,低氧通过低氧诱导因子（hypoxia-inducible factor，HIF）调控的一系列转录因子的活化促进RA的疾病进展［1］。HIF可通过促进RA滑膜细胞（RA fibroblast-like synoviocytes，RA-FLS）增殖和侵袭、调节炎性细胞因子分泌、诱导血管生成及软骨破坏参与RA的发病和病情进展［2-4］。鉴于低氧在RA发病机制中的重要作用，本文对HIF与RA发病机制的研究进展进行综述。

Role of hypoxia-inducible factor in the pathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a destructive chronic autoimmune disease characterized by synovium inflammation, cartilage destruction, bone erosion and the presence of autoantibodies. Hypoxia is a prominent micro-environmental feature in a range of disorders including RA. A combination of increased oxygen consumptionby inflamed resident cells and infiltrating immune cells along with a disrupted blood supply due to vascular dysfunction contribute to tissue hypoxia in RA. Hypoxia in turn regulates a number of key signaling pathways that help adaptation. The primary signaling pathway activated by hypoxia is the hypoxia inducible factor (HIF) pathway. It has been shown that HIFs are highly expressed in the synovium of RA. HIFs mediate the pathogenesis of RA through inducing inflammation, angiogenesis, cell migration, and cartilage destruction, and inhibiting the apoptosis of synovial cells and inflammatory cells. HIF expressed in RA can be regulated in both oxygen dependent and independent fashions, like inflammatory cytokines, leading to the aggravation of this disease. Considering the vital role of HIF in the pathogenesis of RA, we reviewed the new advances about hypoxia and RA. In this review, we firstly discussed the hypoxia-inducible factor and its regulation, and then, the pathologic role of hypoxia in RA, mainly elucidating the role of hypoxia in synovitis and cartilage destruction and immune cells. Finally, we provided evidence about the potential therapeutic target for treating RA.