PM2.5通过调控AhR介导的线粒体自噬促进肝纤维化的作用机制研究

Fine particulate matter (PM2.5) has a significant toxic effect in the liver, and even increase the risk of hepatocellular carcinoma. However, its mechanism has not been explored clearly. Our studies have shown that PM2.5 is able to activate ROS/mitophagy and activate hepatic stellate cells (HSC) , which directs the onset of liver fibrosis. But how PM2.5 activates mitophagy in HSC is still unclear. Our preliminary study showed that the expression of aryl hydrocarbon receptor (AhR), which related to mitophagy significantly increased during the PM2.5-induced activation of HSC. Therefore, it hypothesizes that PM2.5 may promote the activation of ROS/mitophagy and HSC, leading to the occurrence of liver fibrosis by increasing the expression of cytosolic and/or mitochondrial AhR in HSC. We propose to verify that AhR is a key molecular target for PM2.5-induced hepatotoxicity using in vitro and in vivo models. Moreover, we will clarify the roles of AhR and ROS/mitophagy played in PM2.5-induced liver fibrosis.This study aims to figure out the intervention target to prevent PM2.5-induced liver fibrosis.

细颗粒物（PM2.5）在肝脏中的毒性作用不可忽视，甚至可增加肝癌发生风险，但其机制研究尚待深入。申请人课题组前期已在动物染毒模型中首次报道，PM2.5暴露可诱导小鼠肝纤维化，并揭示其机制与PM2.5激活ROS/线粒体自噬，活化肝星状细胞（HSC）相关。然而PM2.5如何在HSC中激活线粒体自噬，机制仍不清楚。在预实验中我们发现，PM2.5促进HSC活化过程中，与线粒体自噬相关的芳香烃受体（AhR）表达上升；故推测：“PM2.5可能通过上调HSC中胞质和/或线粒体AhR的表达，激活ROS/线粒体自噬，促进HSC活化和肝纤维化的发生”。据此本课题拟从细胞和动物水平，验证AhR是PM2.5诱导肝脏毒性效应的关键分子；并深入阐明PM2.5通过调控AhR介导的线粒体自噬促进肝纤维化的作用机制；找到防治PM2.5诱导肝纤维化的干预靶点。

背景：细颗粒物（PM2.5）是一种与空气污染相关的环境因素，可导致肝纤维化。然而，PM2.5对肝星状细胞（HSC）增殖和纤维化的作用和机制仍然未明确。.主要研究内容：人HSC系（LX-2）和小鼠HSC暴露于不同剂量的PM2.5，通过qRT-PCR检测microRNA（miR）-411的表达。通过CCK-8、qRT-PCR、Western blotting和免疫荧光检测细胞增殖、纤维化、线粒体动力学功能障碍和线粒体自噬水平。.结果和数据：PM2.5通过增加ACTA2、胶原1、TIMP1和TGF-β1的水平促进HSC增殖和纤维化。PM2.5降低了miR-411的表达，并通过上调Drp1和降低OPA1、TOM20和PGC-1α水平而导致线粒体动力学功能障碍。PM2.5通过上调Beclin-1、LC3II/I、PINK1和Parkin的水平来促进线粒体自噬。miR-411过表达或使用3-甲基腺嘌呤（3-MA）阻断自噬可减轻PM2.5介导的HSC细胞增殖和纤维化相关因子的表达。Drp1被miR-411靶向，miR-411通过靶向Drp1下调PM2.5诱导的线粒体自噬。Drp1过度表达消除了miR-411在HSC细胞增殖和纤维化相关因子水平中的抑制作用。.结论和科学意义：PM2.5通过降低miR-411促进Drp1介导的线粒体自噬，从而诱导HSC活化，导致肝纤维化。miR-411有望成为PM2.5诱导的肝纤维化干预的新靶点，为预防和治疗长期PM2.5诱导肝纤维化提供新理论和新思路。