肝细胞源性外泌体miR-192通过抑制Rictor激活巨噬细胞诱导非酒精性脂肪性肝炎的机制研究

Non-alcoholic fatty liver disease is the most common chronic liver disease worldwide with serious damage. Non-alcoholic steatohepatitis (NASH) is the turning point of the deterioration of this disease. Therefore, it is important to explore the pathogenesis of NASH and thus achieve effective treatment. Hepatic macrophages play an important role in inducing NASH, but the specific molecular mechanism of macrophages recognizing liver injury signals remains unclear. Our previous studies found that serum exosomes and exosomal miR-192 were increased in NASH patients, and they were correlated with liver inflammation, especially with the infiltration and activation of macrophages. Based on this, we intend to explore the specific mechanism of hepatic macrophage activation by hepatocyte-derived exosomal miR-192 in vivo and in vitro experiments. We aim to identify the key target genes and molecular pathways of miR-192, and to reveal the inducing effect of hepatocyte-derived exosomal miR-192 in NASH, and finally provide new ideas for mechanism exploration and drug development in NASH.

非酒精性脂肪性肝病是全球最常见的慢性肝病，危害严重。其中非酒精性脂肪性肝炎（non-alcoholic steatohepatitis，NASH）是病情恶化的转折点，探讨NASH发病的新机制及寻找有效干预靶点具有重要临床意义。肝脏巨噬细胞在诱发NASH中具有重要作用，但巨噬细胞识别肝损伤信号的具体分子机制尚不清楚。申请者前期研究发现，NASH患者血清外泌体含量及其中miR-192水平显著升高，与肝脏炎症特别是巨噬细胞浸润与活化显著相关。据此，本课题拟利用体内外实验探讨肝细胞源性外泌体miR-192对巨噬细胞的激活作用及机制，明确其调控的关键靶基因及分子通路，旨在阐明肝细胞源性外泌体miR-192对NASH的诱导作用，从而为NASH的机制探索和新药研发提供新思路。

肝脏巨噬细胞可被多种因素如肠道菌群代谢物以及受损的肝细胞释放物等激活。在非酒精性脂肪性肝病（NAFLD）的发生发展中，巨噬细胞向促炎表型（M1）的极化是一个重要的病理生理过程。外泌体可传递多种生物学成分如microRNA、蛋白以及脂质等，因此被作为细胞间通讯的重要媒介。在NAFLD中，外泌体在肝细胞及巨噬细胞对话中的作用尚未明确。.在这项研究中，我们发现脂毒性肝细胞释放的外泌体富含miR-192-5p，这些外泌体可促进M1型巨噬细胞的激活以及肝脏炎症的发生。NAFLD患者的血清miR-192-5p水平与肝脏的炎症活动评分及疾病进展程度呈现显著正相关。同样，在高脂高胆固醇饮食诱导的大鼠模型中，血清miR-192-5p水平与肝脏M1型巨噬细胞数量及肝内促炎因子水平存在显著正相关。脂毒性肝细胞释放的富含miR-192-5p的外泌体较对照组显著增多，它可以诱导CD11b+CD86+巨噬细胞的激活，同时促进iNOS、IL-6和TNF-α的表达。另外，肝细胞来源的外泌体miR-192-5p抑制雷帕霉素不敏感的哺乳动物雷帕霉素靶蛋白伴侣（Rictor）的蛋白表达，进而抑制蛋白激酶B（Akt）和叉头框转录因子O亚族1（FoxO1）的磷酸化，促进FoxO1的激活，最终引起炎症反应的发生。.基于此项研究的结果，肝细胞来源的外泌体miR-192-5p通过调节Rictor/Akt/FoxO1信号通路促进巨噬细胞的活化，进而影响疾病的发生发展。血清外泌体miR-192-5p可作为非酒精性脂肪性肝炎无创诊断标记物及潜在的治疗靶点。