NOD2上调P2Y12受体在细菌感染促血小板活化中的作用机制及干预研究

We have found the expression of P2Y12 receptor in platelet of myocardial infarction patients induced by bacterial infection is significantly increased than that in myocardial infarction patients without infection. Our findings demonstrated that platelet activation induced by infection may be a new mechanism of arterial thrombosis. Based on the previous work and the fact that bacterial infection activates NOD2, an important inflammation receptor in platelet, we put forward the hypothesis that infection can initiate platelet activation via NOD2-RICK-NFкB signaling pathways to raise megakaryocyte P2Y12 expression, to break the balance between the resting state and the activation state. Medicines with reverse agonism such as ticagrelor are better than ordinary anti-platelet therapy to treat this kind of patients.We plan to use the megakaryocyte-specific NOD2 knockout mice and the megakaryocytes in vitro to study the mechanism of auto activation after overexpression of P2Y12. Then we plan to use the bacterial infection animal and platelet in patients with myocardial infarction to study the pathological mechanism of different kinds of reverse inhibitors and their comparison on treating arterial thrombosis.Our study will clarify the mechanism of myocardial infarction induced by bacterial infection and help to choose the optimized therapy to those patients.

近期细菌感染可增高血小板反应性，诱发急性心肌梗死，机制不明。本课题组发现心梗合并细菌感染患者血小板P2Y12受体表达明显升高，基于细菌感染可激活血小板NOD2以及P2Y12激活二态模型理论，创新提出细菌感染可通过 NOD2-RICK-NF-кB 信号通路上调P2Y12、P2Y12高表达后可自发激活、致血小板高反应性及血栓形成假说，并推测此类病人使用反向激动剂（如替格瑞洛）的抗血小板作用优于非反向激动剂（如氯吡格雷）。拟用巨核细胞NOD2基因特异性敲除小鼠和体外细胞实验研究细菌感染上调P2Y12分子机制，应用P2Y12高表达血小板观察下游活化信号通路以反映其自发激活情况；在细菌感染小鼠和冠心病合并细菌感染病人研究P2Y12高表达后血小板高反应性，并验证反向激动剂的抗血小板优势。本项目将阐明冠心病合并细菌感染病人心血管事件新机制，为临床优化选择抗血小板药物防治血栓疾病提供依据。

急性心肌梗死及脑梗死是国人致死致残的主要病因，病人常常继发于呼吸道、肠道感染后，感染病人血栓事件风险增高，探明其机制对降低心脑血管疾病发病率有主要意义，同时对临床上感染合并冠心病病人的抗血小板治疗也有理论指导。本课题从临床感染病人血小板受体表达研究入手，发现感染病人血小板P2Y12受体表达明显升高，P2Y12表达升高使得血小板组成性活性增强，静息状态下下游信号通路活化增强，对ADP的反应性增加，血栓风险增加。我们采用盲肠结扎穿（CLP）模型在小鼠上模拟感染，同样观察到相似的现象，CLP明显增强了小鼠的聚集、释放、铺展，上调了血小板P2Y12表达同时增强了下游信号通路的组成性活化，CLP小鼠血小板对ADP的反应性与P2Y12表达呈正相关。我们采用MEG-01细胞以及NOD2-/-小鼠证实了NOD2受体在感染诱发P2Y12高表达中的作用，NOD2敲除明显抑制了CLP诱导的血小板P2Y12高表达和下游信号通路的组成性活化增强，抑制了巨核细胞RIP2/NFκB/P65信号通路的活化以及P2Y12的表达，减弱了CLP诱导的血小板高反应性和血栓形成。最后我们证实了普拉格雷、替格瑞洛是P2Y12的反向激动剂，它们在感染中的抗血小板作用明显优于中性拮抗剂氯吡格雷，氯吡格雷的抗血小板作用在感染中明显减弱。