P2Y12受体自发激活促进急性心肌梗死患者高血小板活性的作用及干预研究

急性心肌梗死（AMI）患者的双联抗血小板治疗存在“天花板现象”，这意味着有潜在的机制导致了血小板活化未被有效抑制。我们前期发现AMI患者血小板ADP-P2Y12通路活性增强且P2Y12受体表达上调，结合G蛋白偶联受体的二态模型理论，故推测P2Y12受体的自我激活在其中扮演着重要角色。为此，研究拟将AMI患者和心肌缺血大鼠动物模型分别与对照组比较，通过不用ADP激活时P2Y12受体下游通路的分子水平和5羟色胺诱导的血小板聚集来确认P2Y12受体的自发激活；继而以血小板活性、大鼠肠系膜动脉血栓形成及AMI患者临床缺血性事件作为终点来证实其促进了血小板活性并参与了血栓风险；最后通过体外干预血小板和体内干预前期构建的特异性表达自发性激活的P2Y12嵌合体(cP2Y12)转基因小鼠来评估临床使用的P2Y12受体拮抗剂是否能够有效抑制受体的自发激活。

There is a ceiling of benefit from dual antiplatelet therapy in patients with acute myocardial infarction(AMI). The underlying mechanisms remain to be clarified. Our previous study noticed an increased platelet reactivity on ADP-P2Y12 pathway and a higher expression of platelet P2Y12 receptor in patients with AMI. According to the two state model of G-protein coupled receptor, we speculate that constitutive activation of P2Y12 receptor may contribute to increased platelet activity and subsequent thrombotic risk. In this study, patients with AMI and myocardial-ischemic rats would be used to compare with the control group respectively. Platelet P2Y12 expression would be measured by Western blot and Realtime PCR. The constitutive activity of P2Y12 receptor would be confirmed by measurement of downstream signaling pathways in resting platelet and measurement of platelet aggregation induced by serotonin. Then the associations between P2Y12 receptor constitutive activity and platelet reactivity, thrombus formation in mesenteric artery of rats and ischemic outcome in AMI patients would be investigated. Finally, we have generated transgenic mice conditionally and platelet-specifically expressing cP2Y12. Exvivo and invivo study would be conducted to determine whether clinical used P2Y12 receptor antagonists have Inverse agonism to block constitutive agonist-independent P2Y12 receptor activity.