活化型高分子激肽原抑制内皮祖细胞活性在关节炎动脉粥样硬化发展中的作用

Rheumatoid arthritis (RA) is a systemic autoimmune disease which is mainly characterized by destruction of articular structures. Cardiovascular and cerebrovascular diseases are major causes of mortality and morbidity in patients with RA, and most of them develope atherosclerosis (AS). However, the mechanisms underlying vascular complications remain largely unknown. It has been demonstrated that plasma kallikrein-kinin System (KKS) plays an important role in the pathogenesis of RA. We have recently reported that inhibition of KKS activation significantly suppressed synovial recruitment of endothelial progenitor cells (EPCs) and joint inflammation in arthritic animal model. Moreover the activation product of plasma KKS, called cleaved high molecular weight kininogen (HKa) induces EPC senescence in vitro. It has been suggested that vascular endothelium abnormality caused by (EPCs) dysfunction is closely related with the development of atherosclerosis in RA patients.We hypothesize that HKa inhibition of EPC function contributes to the vascular pathology in arthritis. In this proposal we will investigate the in vivo activities of HKa in inhibition of EPCs, by utilizing HK deficient mice based on spontaneous arthritis/atherosclerosis model, combined histologic approaches. We will determine the effects of HKa on EPC survival and vascular repair ability, test whether deficiency of HKa could prevents the development of atherosclerosis during the process of RA. Our study will reveal the role of HKa in the vascular pathology via inhibition of EPC function in the setting of arthritis, which will provide novel insight into the interplay between arthritis and the development of atherosclerosis.

类风湿性关节炎(RA)是以关节障碍为主的自身免疫疾病。RA患者高发心血管动脉粥样硬化性疾病是其死亡的主要原因。目前RA血管并发症的发病机制仍不清楚，已成为亟待解决的临床难题。大量研究表明，血浆激肽释放酶-激肽系统(KKS)在关节炎发病中起重要作用。我们研究发现，阻断KKS活化能抑制内皮祖细胞(EPCs)向关节炎症滑膜归巢，并有效控制关节炎发病；KKS活化产物活化型高分子激肽原（HKa）在体外具有抑制EPCs功能的作用，而EPC功能异常与血管内皮障碍密切相关。因此本项目的假说是，KKS活化产物HKa抑制EPCs功能，参与关节炎血管并发症的发生。本项目将应用HK基因敲除小鼠，建立自发性关节炎合并动脉粥样硬化疾病模型，结合病理组织学等方法，在体判定HKa是否抑制关节炎EPCs功能，阻碍损伤血管内皮修复从而加速动脉粥样硬化，并剖析其机制。这将为揭示RA与血管并发症的演变关系提供新的认识和研究思路。

类风湿性关节炎(Rheumatoid arthritis,RA)患者普遍存在动脉粥样硬化Atherosclerosis，AS）并发症， 这种现象与内皮祖细胞（Endothelial Progenitor Cells,EPCs）功能异常密切相关。EPCs功能异常导致的血管内皮障碍,是启动动脉粥样硬化的关键，成为心血管疾病危险性增加的主要独立因素之一。但何种机制调节了EPCs的功能障碍仍不清楚。本项目应用基因敲除小鼠，建立自发性关节炎合并动脉粥样疾病模型，从疾病的表型，EPCs细胞生物学活性及炎症因子调控等方面研究，判定HKa抑制内皮祖细胞功能的血管病理学作用及机制。研究结果表明血浆HKa及其上游活化酶Kallikrein、下游受体B1RB2R的缺失，可有效缓解小鼠关节炎的发病，显著抑制炎症因子的水平。HKa通过激活JNK在Thr183/Tyr185位点、FOXO4在Thr451位点的磷酸化来上调EPC胞内MnSOD mRNA水平及蛋白表达水平，增加胞内活性氧ROS的产生，从而加速EPCs的衰老。进一步定位HKa的功能域发现HKa通过其重链部分（Hevavy chain，HC, 19–380aa）作用于EPCs发挥作用。这些研究结果说明HKa促进关节炎炎症发展，通过JNK/FOXO4/MnSOD/ROS/p38/p16信号途径抑制内皮祖细胞功能，从而在关节炎动脉粥样硬化并发症的发生和发展中发挥重要作用，为深入研究RA血管并发症的发生与发展提供了新认识。