心肌细胞PKI抑制PKA激活对脓毒症心肌抑制的作用和机制研究

The mortality of cardiac dysfunction caused by sepsis can be as high as 70 - 90%，, and there is no special effective treatment in clinic. Sympathetic overactivity and inflammation play the important roles in the pathophysiological process of cardiac dysfunction during sepsis. PKI is a thermal stable polypeptide expressed in the heart, which is a specific protein to inhibit the activation of PKA. The effect of PKI on cardiac arrest caused by sepsis in the heart has not yet been reported. Our preliminary experimental data showed that inhibition of PKA by overexpression of PKI-GFP in cardiomyocytes could prolong survival time, and enhance cardiac function in LPS-induced septic mice. Further studies showed that the specific overexpression of PKI-GFP in cardiomyocytes also could reduce the apoptosis of cardiomyocytes, inhibit myocardial fibrosis and alleviate inflammatory infiltration in myocardium of septic mice. Therefore, we speculate that the beneficial effect of PKA inhibition in cardiac myocytes may be associated with the reduction of myocardial inflammation in septic mice. This project aimed to study: 1) Does the PKA inhibition in cardiac myocytes can benefit the prognosis of sepsis? Whether the protective effect on sepsis by PKA inhibition in cardiac myocytes is related to the reduction of myocardial inflammation in septic mice? 2) How does PKA inhibit in cardiac myocytes produce the anti-inflammatory effect in the myocardium? What is the signal pathway?

脓毒症(sepsis)所致心肌抑制患者病死率可高达70～90%，目前临床上尚无特别有效的治疗办法。在脓毒症心肌抑制的病理生理机制中炎症和交感肾上腺素能神经系统持续过度激活扮演了重要角色。PKI是心脏中表达的一种特异性抑制PKA的热稳定多肽，心脏中PKI对脓毒症所致心肌抑制有何作用？至今尚未见报道。我们发现在心肌细胞特异性过表达PKI（PKI-GFP）抑制PKA激活能够显著延长LPS诱导的脓毒症小鼠的存活时间，并增强其心功能。进一步研究发现心肌细胞特异性过表达PKI抑制PKA激活能减少脓毒症小鼠心肌细胞的凋亡和纤维化，减轻LPS诱导的心肌炎症细胞浸润。因此，我们推测心肌细胞PKA抑制保护脓毒症预后可能与其能够减轻心肌炎症有关。因此，本项目拟围绕1）心肌细胞PKA抑制是否能保护脓毒症预后？其机制是否与其减轻心肌炎症有关？2）脓毒症时，心肌细胞PKA抑制是如何减轻心肌炎症的？其信号通路如何？

脓毒症(sepsis)所致心肌抑制患者病死率可高达70～90%，目前临床上尚无特别有效的治疗办法。在脓毒症心肌抑制的病理生理机制中，炎症和交感肾上腺素能神经系统持续过度激活扮演了重要角色。 PKI是心脏中表达的一种特异性抑制PKA激活的热稳定多肽，心脏中PKI对脓毒症所致心肌抑制的作用和机制如何？至今尚未见报道。在本项目执行过程中，申请人根据前期研究基础，着重围绕心肌细胞过表达PKI抑制PKA激活对脓毒症的作用及机制展开研究，发现：1）心肌细胞特异性过表达PKI抑制PKA能改善脓毒症小鼠的心脏功能、延长存活时间、提高生存率；2）心肌细胞特异性过表达PKI抑制PKA激活能改善脓毒症诱导的心肌细胞炎症、凋亡和心肌纤维化；3）心肌细胞特异性过表达PKI抑制PKA激活抑制脓毒症心肌凋亡的作用与其改善心肌细胞线粒体功能、增加脓毒症时心肌细胞的能量供应密切相关。该项目的研究结果有助于理解心肌细胞PKA在脓毒症心肌抑制时的作用及其机制，为脓毒症心肌抑制患者的临床治疗提供新思路，也为药物开发提供新靶点。在该项目的资助下共发表SCI论文5篇（其中1篇已修回），其中影响因子大于10的有1篇、影响因子大于5的有2篇；培养博士研究生2名和硕士研究生2名；项目负责人获得上海市科技进步一等奖（7/15）；总体来看，该项目任务圆满完成。