RIP2调控CD40-NF-кB信号通路在血管内皮细胞损伤中的作用机制研究

Atherosclerosis is a complex chronic inflammatory disease. Vascular endothelial cell injure is considered to be an early event which subsequently leads to atherosclerosis. CD40 signal is the key regulator in inflammatory immune responses. Studies indicated that inflammatory reaction resulting from the activation of NF-κB pathway mediated by CD40 is closely related to vascular endothelial cell injure. However, mechanism of inflammatory response on endothelial cell has not fully elucidated so far. TNFR-associated factor 3 (TRAF3) as a cytoplasmic protein physically binds to the cytoplasmic domain of CD40 and mainly involved in the control of non-canonical NF κB signaling. We identified that RIP2 was a novel TRAF3 binding partner by yeast two-hybrid screen in our previous studies. The interaction between TRAF3 and RIP2 was reconfirmed in vitro and in vivo, using GST pull-down, co-immunoprecipitation and mammalian two-hybrid assays.Meanwhile, we found that the expression level of RIP2，CD40，TNFα and ICAM-1 in the arterial vascular tissues of atherosclerosis model animals were respectively higher than that in control group. We also observed the elevated expression level of RIP2 and NIK in human umbilical veins vascular endothelial cells (HUVEC) with CD40L activation. The results imply that RIP2 might affect the negative regulation of TRAF3 involved in the non-canonical NF κB pathway by interaction with TRAF3, promoting inflammatory response on vascular endothelial cells and contributing to the enhancing vascular endothelial cells injure. Therefore, to better understand the vascular endothelial cells injure, it is valuable for studying the effect of interaction between TRAF3 and RIP2 on CD40-NF κB pathway and molecule mechanism, which will not only elucidate the effects of RIP2 on vascular endothelial cells injure but also will provide new therapy target and lay the theory basis for the AS clinical therapy.

动脉粥样硬化（AS）是复杂的慢性炎症性疾病，血管内皮细胞损伤是AS形成早期的关键环节。CD40信号是炎症免疫反应的枢纽，研究表明在AS中，CD40激活NF-κB通路引起的炎症反应与血管内皮细胞损伤密切相关，但其具体作用机制尚不完全清楚。TRAF3是CD40胞内接头分子具有负调控非经典NF-кB信号通路作用。我们前期研究发现并证实受体相互作用蛋白2（RIP2）与TRAF3具有相互作用。此外，在AS模型动物主动脉血管组织中也发现RIP2、CD40、TNFα和ICAM-1表达水平升高；同时CD40L刺激人脐静脉血管内皮细胞(HUVEC)也引起RIP2及NIK表达水平升高。这些研究结果提示RIP2可能通过与TRAF3作用影响后者对CD40介导的NF-кB信号通路的负调控，从而促进血管内皮细胞炎症反应导致细胞损伤。因此深入研究RIP2通过TRAF3对CD40-NF-кB信号通路的调控作用及分子机制，不仅能够阐明RIP2在血管内皮细胞损伤中的作用，同时能为AS治疗提供新的靶点和思路。