心脏干细胞源μ阿片受体经Caveolin-3/MG53通路介导吗啡预处理减轻慢性心衰心肌缺血后损伤的作用及机制

When the patient with chronic heart failure (CHF) undergo cardiac surgery, the heart is more likely to suffer from myocardial ischemia/reperfusion injury, what’s more, large number of researches suggested that the cardioprotective effect of ischemic or pharmacological conditioning is weakened in failure heart. Our previous study has showed that morphine preconditioning protects the failing heart against ischemia/reperfusion injury, and this protection is dependent on the up-regulated cardiac μ opioid receptor. However, the issue that the origin of the increased μ opioid receptor and its role in opioids preconditioning mediated cardioprotection still remains unclear. Studies have shown that the μ opioid receptor is mainly expressed in the early stage of the formation of the heart，and the proliferation and differentiation of cardiac stem cell into cardiomyocytes is significantly increased in CHF. However, the relationship between the up-regulation of μ opioid receptor and cardiac stem cell is still dimness. It is reported that opioid receptor is closely related to Caveolin-3 whose interaction with MG53 plays a crucial role in the conditioning-induced cardioprotection. In this study, we will establish the post-infarction heart failure to observe the up-regulated expression of μ opioid receptor and its relationship with cardiac stem cell at gene, protein and receptor levels in different development stages of CHF. Furthermore, we will investigate the molecular mechanism of μ opioid receptor mediated cardioprotection by morphine preconditioning via Caveolin-3/MG53 pathway in the failing heart. The study will provide new perspectives for the treatment of myocardial ischemia/reperfusion injury in patients with CHF during cardiac surgery.

合并慢性心衰的患者接受心脏手术时更易发生心肌缺血后损伤，且对多种心肌保护策略不敏感。然而我们前期发现阿片预处理仍然可以减轻慢性心衰心肌缺血后损伤，该作用与心衰心脏中μ阿片受体表达上调有关，但上调的μ阿片受体源自何处及其介导阿片预处理心肌保护的信号机制仍未明确。研究表明，μ阿片受体主要在发育早期的心脏中表达，而慢性心衰心脏中心脏干细胞增殖分化形成心肌细胞明显增多，上调的μ阿片受体是否源于新分化的心肌细胞？已知阿片受体与微囊蛋白-3关系密切，而微囊蛋白-3与MG53相互作用形成复合物是心肌保护的重要分子机制。本课题拟通过梗死后慢性心衰模型，在基因、蛋白与受体层面研究慢性心衰发展的不同阶段μ阿片受体表达上调情况及其与心脏干细胞的联系；并在离体心脏及细胞水平探讨吗啡预处理经μ阿片受体调控微囊蛋白-3/MG53通路发挥心肌保护的信号机制，为临床防治慢性心衰患者在心脏手术中心肌缺血后损伤寻找新靶点。

慢性心力衰竭是各种心脏疾病的终末阶段。研究表明，经典的内源性心肌保护策略缺血预处理不能有效地减轻慢性心衰心肌缺血后再灌注损伤，而阿片类药物预处理仍可以发挥心肌保护作用，但其作用机制及临床效应仍不明确。本研究利用梗死后慢性心力衰竭大鼠模型及拟行体外循环手术的慢性心衰患者作为研究对象，首先采用分子生物学手段对心衰心脏中的mu-, delta-, kappa-阿片受体表达进行了系统的检测与分析，同时验证与观察了吗啡预处理（MPC）对梗死后心衰大鼠及慢性心衰患者心肌缺血再灌注损伤后的作用及临床预后的影响，并阐述MPC在心衰心脏中发挥心肌保护作用的分子机制。此外，本课题还对缺血预处理诱导的外泌体在心衰心脏中的心肌保护作用及机制做了初步的研究。通过系列的研究发现mu-, delta-阿片受体在慢性心衰大鼠及患者心脏中的表达显著增高，且与心脏功能呈显著的线性相关，而kappa-阿片受体无明显变化。MPC不仅可以减轻梗死后心衰大鼠心脏的缺血后再灌注损伤，也可以改善体外循环术后慢性心衰患者的心肌损伤水平，同时具有降低住院期间并发症，提高患者短期预后的趋势。进一步研究显示，MPC在心衰心脏中可能是通过提高Caveolin-3表达，激活细胞内EKR蛋白激酶，降低心肌细胞凋亡水平发挥心肌保护。而缺血预处理在心衰心脏中心肌保护作用的减弱与外泌体功能缺失有关，在正常大鼠中缺血预处理诱导的血清外泌体可以通过活化再灌注损伤补救激酶通路减轻梗死后心衰大鼠心脏的缺血再灌注损伤。本研究为防治慢性心衰患者实施心脏或非心脏手术时心肌缺血后再灌注损伤提供新的方法，同时对阿片类药物合理应用于临床心衰患者中具有指导意义。