β1整合素保护脓毒症诱发心肌损伤的细胞分子机制

Sepsis-induced myocardial dysfunction is one of the focuses for clinical and basic research in the field of critical care medicine. Our previous studies have shown that insufficient expression of integrin (ITG)β1 was associated with sepsis-induced cardiac dysfunction, the cardiac function and hemodynamics in septic rat can be improved by upregulation of ITGβ1 protein expression, however, the protective mechanism is unclear. This study is aimed to use septic rats, established by cecal ligation and puncture, and LPS-stimulated cultured cardiomyocytes as the research objects; and use lentiviral vectors to mediate overexpression and interference of ITGβ1 gene for subsequent cardiac-targeted gene transfer and cell transinfection in vitro, respectively. By investigating the impacts of upregulation or inhibition of ITGβ1 gene on cardiac structure and function, myocardial viability, apoptosis, energy metabolism, autonomic function and relevant signaling pathways, the cellular and molecular events and the vital signaling pathways or regulating signaling molecules that contribute to ITGβ1-mediated cardiac protection will be clarified; and finally the cellular and molecular mechanisms responsible for ITGβ1-mediated cardiac protection in septic rat will be discovered. Meanwhile, the safety of ITGβ1 gene therapy will be evaluated, which will provide a theoretical basis for subsequent clinical translation.

脓毒症诱发的心功能不全是危重病领域临床和基础研究热点之一。我们既往研究表明整合素(ITG)β1表达不足与脓毒症诱发的心功能不全有关，上调ITGβ1蛋白表达可以改善脓毒症大鼠心脏功能和血流动力学状态，但其保护机制不清楚。本研究拟以盲肠结扎穿刺建立的脓毒症大鼠和脂多糖刺激的培养心肌细胞为研究对象，构建ITGβ1过表达和干扰慢病毒质粒，分别进行心脏定向ITGβ1基因转移和体外转染。动态观察上调和抑制ITGβ1的基因表达对动物心功能、心肌存活性、细胞凋亡、能量代谢、自主神经功能和相关信号转导通路的影响，明确与ITGβ1介导心脏保护相关的细胞和分子事件、发现关键信号通路或调控信号分子，最终阐明ITGβ1保护脓毒症大鼠心脏的细胞分子机制；同时评价ITGβ1基因治疗的安全性，为后续的临床转化提供理论依据。

脓毒症诱发心脏功能障碍（SIMD）增加患者死亡率，临床上无特异治疗，其原因与SIMD发病机制不明确有关。前期研究发现整合素β1 可以保护SIMD，本研究探讨整合素β1 介导对SIMD保护作用的相关细胞分子机制。经体内体外实验研究证实：1. 整合素β1改善SIMD和动物血流动力学状态与其维持心肌细胞膜稳定性有关；2. 整合素β1改善SIMD和动物血流动力学状态与其保护心肌线粒体结构、稳定膜电位、改善线粒体动力学（融合与分裂）、平衡线粒体凋亡与自噬有关；3. 整合素β1改善SIMD和动物血流动力学状态可能通过强化保护性FAK/Src通路、稳定细胞骨架、改善能量代谢通路而实现。该研究结果可望为后续研究提供新的思路，即SIMD可能主要是脓毒症引起心肌能量代谢障碍所致，其研究应该聚焦于线粒体和代谢相关蛋白。