整合素β1保护脓毒症心肌功能障碍的线粒体机制

The mortality rate in patients with sepsis related myocardial dysfunction (SRMD) is significantly increased, with limited treatment, mainly because of its mechanism is not yet fully clear. Energy depletion due to sepsis mediated myocardial mitochondrial damage is one of the important mechanisms of SRMD. Interventional strategies against mitochondrial damage are expected to improve the outcome of patients with SRMD. In our previous study, mitochondrial damage accompanying by a significant downregulation of myocardial extracellular matrix component integrin β1 was found in SRMD. Upregulation of integrin β1 could improve cardiac function and hemodynamic status, protect cardiomyocytes and mitigate myocardial mitochondrial damage in septic animals. Based on our previous studies, the aim of the present study was to investigate the myocardial mitochondrial mechanism involved in integrin β1 mediated protection in septic rats and LPS-induced cardiomyocytes. By investigating the role of integrin β1 (overexpression and interference) in myocardial mitochondrial morphology and function, mitochondrial apoptosis and autophagy, mitochondrial dynamic balance, and mitochondrial damage related signaling pathways in vitro and in vivo., the effect of integrin β1 on the mitochondrial regulatory network of SRMD, the core mitochondria-based cell events and the key signaling molecules, and finally new interventional targets against SRMD will be identified. The achievements of this project might provide novel insights and choice for effective clinical treatment of SRMD.

脓毒症心肌功能障碍（SRMD）患者死亡率显著升高、临床治疗手段有限，主要是因为其发病机理尚未完全明确。脓毒症致心肌线粒体损害引起心肌能量代谢障碍是SRMD重要机制之一，针对线粒体损害的干预手段有望改善SRMD患者预后。我们前期研究SRMD时发现脓毒症中线粒体损害的同时伴有心肌细胞外基质成分整合素β1显著下调，上调整合素β1可以改善脓毒症动物心功能和血流动力学状态、保护心肌细胞、减轻心肌线粒体损害。本项目拟在此基础上开展在体和体外实验，研究整合素β1保护脓毒症动物心脏和LPS刺激心肌细胞的线粒体机制，通过整合素β1（过表达与干扰）对心肌线粒体形态和功能、线粒体凋亡与自噬、线粒体动力平衡、线粒体损害相关的关键信号通路的影响，明确整合素β1保护SRMD的完整线粒体调控网络、确认其中基于线粒体的核心细胞事件和关键信号分子、最终发现新的干预靶点，为临床更加有效治疗SRMD提供新的思路和选择。

我们此前发现整合素β1表达异常低下与大鼠脓毒症心肌功能障碍（SIMD）有关，上调整合素β1的表达，可以起到保护SIMD的作用。本项目探索整合素β1保护SIMD的线粒体机制，主要研究结果：1）SIMD心肌线粒体存在形态学破坏和动力学异常，上调整合素β1可以促进线粒体形态恢复、促使动力学趋向平衡。2）心肌整合素β1保护SIMD的非线粒体机制包括：①减少心肌细胞凋亡，②增强心肌细胞骨架蛋白丰度，③改善心肌细胞膜稳定性。3）SIMD时心肌线粒体出现Sirt3依赖性代谢重塑，表现为TCA循环效率低下、糖酵解活动增强、乳酸蓄积明显。乙酰化蛋白质谱分析：TCA循环关键酶蛋白高度乙酰化伴有活性下降；代谢组学分析：TCA循环、戊糖磷酸途径和糖酵解途径能量代谢效率均下降，表现为草酰乙酸、琥珀酸、6-磷酸葡萄糖G6P、6-磷酸果糖G6F、丙酮酸等代谢中间产物表达明显增多；以活性小分子大黄素靶向干预线粒体内去乙酰化酶Sirt3，可以改善脓毒症心肌能量代谢效率；4）最新发现：SIMD病程中，损伤机制除了PAMPs/DAMPs直接攻击心肌细胞之外，尚有“远程打击”机制参与；即肝细胞来源的血管紧张素原（AGT）通过“肝心轴”介导了SIMD。开展研究期间本团队发表标注基金号的学术论文12篇，参加学术会议4人次，培养研究生6人