载脂蛋白A-I对肝脏缺血再灌注损伤炎症反应的调控作用及机制研究

Hepatic ischemia reperfusion injury (IRI) is an inevitable problem during liver transplantation. Increasing evidence showed that hepatic IRI is a typical inflammatory response involving a complex web of interactions between various cellular and molecular signals. Macrophages play important roles in hepatic IRI-induced inflammatory response. Apolipoprotein A-I (ApoA-I), the primary protein component of HDL, was closely associated with the development of many inflammatory diseases. Our preliminary results showed that the expression of ApoA-I was decreased in liver graft after transplantation, associated with liver injury and inflammatory response. The knockout of ApoA-I accelerated liver injury while the treatment of ApoA-I attenuated hepatic IRI. Our hypothesis is ApoA-I attenuates liver IRI through regulating hepatic inflammatory response. In this project, we aim to investigate the roles of ApoA-I in liver IRI induced inflammatory response and to explore the underlying mechanisms through in vivo and in vitro studies. Our results will be important not only for understanding the roles and molecular mechanisms of ApoA-I in liver IRI but also for developing a new therapeutic strategy to reduce liver IRI after transplantation.

肝脏缺血再灌注损伤（IRI）一直是肝移植无法避免的病理生理过程，是影响肝移植成功的一个重要因素。肝IRI是典型的炎症反应过程，巨噬细胞在其炎症反应中起着重要作用，其调控机制还不清楚。载脂蛋白A-I（ApoA-I）可通过抑制炎症反应，缓解动脉粥样硬化等疾病进程。前期实验表明，肝移植术后ApoA-I低表达，并与肝损伤程度及炎症反应密切相关。 敲除ApoA-I基因加重肝IRI及巨噬细胞浸润，而ApoA-I治疗减轻肝IRI。因此我们假设ApoA-I通过抑制肝脏炎症反应，减轻肝IRI。本课题同时采用ApoA-I基因敲除小鼠及ApoA-I治疗，研究ApoA-I在肝脏IRI及炎症反应的作用。体外实验通过分离原代肝脏巨噬细胞、骨髓源性巨噬细胞，分析ApoA-I在巨噬细胞激活、极化、迁移中的作用及机制。本课题旨在阐明ApoA-I在肝IRI及炎症反应中的作用机制，为临床缓解肝IRI提供新的治疗思路和理论依据。

肝脏缺血再灌注损伤（IRI）一直是肝移植无法避免的病理生理过程，是影响肝移植成功的一个重要因素。研究显示肝IRI是典型的炎症反应过程。载脂蛋白A-I（ApoA-I）在抗炎过程中起着重要的作用，与多种炎症性疾病如非酒精性脂肪性肝炎、动脉粥样硬化的发生发展密切相关。目前ApoA-I在肝IRI及术后肝再生的作用及机制尚不清楚。本课题采用ApoA-I基因敲除小鼠，通过体内体外实验相结合，研究ApoA-I在肝脏IRI及其损伤后肝再生的作用及机制。结果显示肝移植术后肝脏ApoA-I表达降低。体外结果也证实，小鼠原代肝细胞经缺氧/富氧损伤后ApoA-I表达降低。敲除ApoA-I基因后血清ALT/AST升高，加重了肝脏IRI。此外，敲除ApoA-I提高caspase3，BAX，NLRP3，GSMSD，caspase1，caspase4，IL-1β等凋亡和焦亡相关基因的表达。ApoA-I治疗后减弱巨噬细胞的激活，减少IL-1β,IL-6,IL-18,TNFα炎症因子的表达。另外，研究显示小体积脂肪供肝移植后的再生能力明显弱于正常供肝且ApoA-I的表达明显降低。体外实验显示，ApoA-I促进肝细胞的增殖，缓解肝细胞的脂肪变性。体内实验显示，ApoA-I治疗能有效促进小鼠肝再生和细胞周期蛋白cyclinA2、D1、E1的表达。ApoA-I治疗提高PGC-1α, Tfam, Ucp2和SDHB的表达，促进线粒体的生物合成及能量代谢。以上结果表明，ApoA-I在肝脏IRI及其损伤后肝再生中起着重要的作用，ApoA-I可缓解肝IRI和加速损伤后肝再。此研究结果为临床缓解肝IRI和术后肝再生提供新的治疗方式。