MIF在老龄心肌缺血再灌注损伤中的作用机制及其靶向干预研究

Aging is considered as a major risk factor for acute myocardial infraction. Recently, we used myocardial ischemia-reperfusion injury mouse model, we found that the factor of aging increase the sensitivity to myocardial ischemia- reperfusion injury. The cardiac MIF protein expression significantly decreased when compared with the control group, but the mechanism is not clear, MIF gene can specifically activate AMPK and ERK1/2 signaling pathways to protect against young myocardial ischemic injury. Therefore, we hypothesize that the “MIF-AMPK/ERK1/2” cascade signaling pathway regulates the cardiac endogenous protective mechanism of energy metabolism and mitochondrial homeostasis. Accordingly, this study intends to use the model of myocardial ischemia-reperfusion injury to explore the susceptibility mechanism of MIF in aging related myocardial ischemia. Meanwhile, we construct the recombinant AAV9 vector which can targeted express MIF gene in heart. Via in vivo and in vitro transfection experiments, we can clarify the molecular mechanisms of MIF targeting expression reduce the myocardial ischemia injury at the cellular, tissue and whole animal level. Then based on intervention experiments of exogenous MIF importation in aging mice, the utility of MIF as ischemia-reperfusion injury therapeutic target of aging can be identified, it can also provide new ideas and basis to alleviate and improve the prognosis of ischemia-reperfusion injury in patients with acute myocardial infraction.

老龄是急性心肌梗死(AMI)发病的高危因素。我们最近利用心肌缺血再灌注（I/R）损伤模型，发现老龄加重心肌I/R损伤的敏感性，且巨噬细胞移动抑制因子MIF表达较年轻对照显著降低，但机制不清楚，MIF基因能特异性激活AMPK及ERK1/2信号通路，抵抗年轻心肌缺血损伤。据此，提出“MIF-AMPK/ERK1/2”级联信号通路调控心肌能量代谢、稳定线粒体功能的心肌内源性保护机制假说。本课题拟采用心肌I/R模型，探讨MIF在老龄心肌缺血损伤易感性中的作用机制；同时，利用重组MIF基因的AAV9载体，通过体内外转染实验，在细胞、组织及动物整体水平上，揭示MIF基因靶向表达对抗老龄心肌缺血再灌注损伤的分子机制；基于老龄鼠体内外源导入MIF干预实验，确定MIF作为老龄心肌缺血再灌注损伤治疗靶标的效用，为减轻AMI患者缺血再灌注损伤、改善预后提供新的思路和依据。

再灌注治疗是急性心肌梗死（AMI）最为有效的治疗手段，但是会带来心肌缺血再灌注损伤（Ischemia/reperfusion，I/R），本项目开展了MIF在老龄心肌缺血再灌注损伤中的作用机制及其靶向干预效果研究。首先在活体动物整体水平发现老龄心肌MIF表达水平较年轻心肌显著降低，抑制AMPK及ERK1/2活性导致老龄心肌缺血再灌注损伤的敏感性增加。其次，构建心肌高效快速表达MIF基因的双链重组AAV9（AAV9-MIF）载体，在体外细胞水平发现外源性导入MIF基因通过激活AMPK及ERK1/2信号通路，激活自噬，稳定线粒体功能，抑制心肌细胞凋亡，从而减轻缺氧/复氧对心肌细胞造成的损伤。另外，在活体动物整体水平，发现MIF在心肌中的靶向表达，在心肌缺血阶段通过活化AMPK激活心肌自噬效应，再灌注早期激活ERK1/2通路（磷酸化ERK1/2，p70S6K，GSK3β）提升心肌内源性抗损伤能力，以此减轻氧化应激、抑制细胞凋亡，缩小梗死面积并改善心功能，有效防治年轻、老龄以及老龄MIF KO小鼠心肌缺血再灌注损伤。明确AAV9-MIF可作为基因治疗药物，有望成为对抗心肌缺血再灌注损伤的有效手段。