MCPIP：调控巨噬细胞表型与活性对动脉粥样硬化发生、发展的作用研究

Atherosclerosis is a chronic inflammatory disease. Macrophages have a key role in foam cell formation and in the atherosclerotic plaque progression. Phenotypical and functional specialization of macrophages are key physiological regulators of both innate and adaptive immunity. The classically activated macrophages, M1, destructive macrophages promotes the inflammation, and the alternatively activated macrophages, M2，reparative macrophage suppresses the inflammation, both the M1 and M2 maintain immune homeostasis and modulate immune responses during inflammation. To accomplish these tasks, macrophages activity are precisely controlled, and this requires macrophages to alter their migratory, functional and homeostatic properties in response to specific cues in the immune environment. Evidence is also emerging of the involvement of MCP-1 induced protein (MCPIP)in disease of the immune system. In this study, we investigate the role and the mechanisms of MCPIP on the macrophage phenotypical and functional activity and in the development of atherosclerosis..In our previous studies, we have demonstrated that regulation of inflammation and immune of MCPIP in autoimmune myocarditis. In the present study, we modulate the MCPIP molecule expression positively or negatively to generate new macrophages that over-expression of MCPIP, and to generate new macrophages that knockdown (RNAi) the expressionof MCPIP. In vivo and in vitro study, we observe the effects og macrophages that MCPIP over-expression or MCPIP deficiency on the early fatty streak formation and advanced fibrofatty development in the pro-atherosclerotic apo E knockout mice. We would demonstrate that the MCPIP modified macrophages have an impotant role in the formation/progression of atherosclerosis, and the modified macrophages affect the plaque vulnerablity.

巨噬细胞(MΦ)是一种多向性细胞，不同活性的MΦ对炎症的作用不同，替代激活的MΦ（M2）促进炎症的修复，而经典激活的MΦ（M1）则加重炎症。损伤性和修复性的MΦ总处于动态平衡，而疾病的转归不仅取决于MΦ的数量更重要的是MΦ的活性状态。我们前期的研究提示M1细胞促进AS炎症发展、泡沫细胞形成和斑块不稳定；M2细胞促进血管炎症修复及斑块稳定。但如何调控MΦ表型？不同的炎症微环境如何影响MΦ表型分化？我们最近的研究提示，MCP-1诱导蛋白（MCPIP）可能在其过程中起关键性的作用。本研究拟进一步观察AS的形成和发展不同阶段，斑块中不同活性的MΦ中MCPIP表达及定位，阐明MΦ表型与活性改变在AS中的作用；通过构建MCPIP蛋白过表达和表达抑制的MΦ，观察选择性表达/抑制MCPIP对MΦ表型和活性的影响；在体观察改变MCPIP蛋白表达、修饰MΦ表型和活性后对AS斑块发展、特别是斑块的稳定性的影响。

巨噬细胞(MΦ)为多向性细胞，替代激活和经典激活的MΦ决定炎症是修复或进展。不同活性的MΦ处于动态平衡，As的转归取决于MΦ的数量和活性状态，控制MΦ的活性将对As斑块进展及斑块稳定性产生重要影响。如何调控MΦ表型？不同的炎症微环境如何影响M Φ表型分化？哪些蛋白分子影响MΦ表型分化？是本研究的重点。我们的研究结果表明：MCP-1诱导蛋白MCPIP在血管内皮细胞功能障碍中具有重要作用。循环中的MCP-1其通过和血管内皮细胞上CCR2的结合而诱导该细胞中MCPIP的高表达，高表达的MCPIP又会造成细胞内氧化应激（ROS）的增加及后续的eNOS来源的NO生物利用度下降。特异性的siRNA敲低内皮细胞中MCPIP表达能够恢复eNOS的磷酸化及NO的生物利用度；过表达MCPIP后eNOS磷酸化下降且NO生物利用度受损；巨噬细胞高表达MCPIP后M2表型的标记物显著升高，且对LDL诱导的炎症反应减轻，表明高表达MCPIP后巨噬细胞向M2分化；而敲除MCPIP表达后巨噬细胞向M1细胞分化和脂质吞噬作用增强；提示MCPIP调节巨噬细胞表型和活性与AS的进展密切相关；进一步的在体研究证实MCPIP调节MΦ表型和活性：改变AS模型鼠基因，敲除MCPIP后巨噬细胞表型向M2细胞分化，表现为巨噬细胞的胆固醇逆转运增强、体内血脂水平降低；同时在体观察到LDLR基因敲除鼠的动脉粥样硬化斑块面积减少，斑块内的胶原含量增加、活化的巨噬细胞数量减少、平滑肌数目增加，提示斑块的稳定性增加。这些结果为探讨AS的防治新战略提供了新的分子细胞学依据。