p62介导的Keap1-Nrf2-ARE途径在肺纤维化进程中作用及其调控机制

Idiopathic pulmonary fibrosis (IPF) is a serious disease, the exact pathogenesis of which remains unclear. Fibroblast proliferation and apoptosis insufficient are essential in the formation of IPF. Autophagy is closely associated with IPF development and the decreased autophagy level is accompanied with the accumulation of p62. Nrf2 is a key protective transcription factor in oxidative stress, it has been reported that the sustained p62 expression activate Nrf2, which regulates the downstream gene transcription and facilitates fibroblasts proliferation and fiber repair. Therefore, we speculate that p62 may be involved in the progression of IPF by mediating Nrf2-Keap1 signaling pathway. To confirm this hypothesis, we intend to adopt p62 gene knockout and wild type mice and cell model in PF, to observe the expression and localization of p62 and the involved mechanism of p62 in lung fibroblast proliferation, apoptosis, and ECM deposition, and to explore whether p62 is involved in the activation of Nrf2-Keap1 pathway and the regulatory role of p62-mediated Keap1-Nrf2 pathway in the progression of IPF, to find new target for IPF prevention and treatment, and provide new ideas and approaches for the clinical treatment of IPF.

特发性肺纤维化(IPF)危害严重，其确切机制尚未完全阐明。成纤维细胞增生或凋亡不足是肺纤维化形成机制中重要的环节。自噬与IPF发生密切相关，肺纤维化中自噬水平明显降低，伴有p62蛋白聚集。Nrf2是氧化应激中起关键保护作用的转录因子，研究发现p62持续表达能激活Nrf2，后者调控下游相关基因转录，进而促进成纤维细胞存活和组织纤维修复。因此我们推测肺纤维化中p62聚集可能通过介导Nrf2-Keap1信号通路参与调控肺纤维化进程。为证实这一假说，本项目拟在p62基因敲除、野生型小鼠和细胞PF模型上，观察p62的表达和定位情况以及p62与肺纤维化成纤维细胞增殖、凋亡和ECM形成的关系，探讨p62的作用是否与Nrf2-Keap1通路激活有关，以及p62介导的Nrf2-Keap1途径在肺纤维化进程中的调控作用，探索IPF防治新靶点，为临床防治肺纤维化提供新思路和新方法。

特发性肺间质纤维化（IPF）是一种以细胞外基质沉积和纤维化为特点的慢性、致死性疾病。IPF目前发病原因不明，吸烟及环境因素在疾病的发生发展中均起到一定作用。前期研究表明抗氧化关键因子Nrf2在肺纤维发病过程中发挥保护作用。既往研究证实了上皮间质转化（EMT）、成纤维细胞向肌成纤维细胞分化（FMD）以及自噬参与了IPF的发生发展，但具体机制不明。本项目利用博来霉素在Nrf2敲除小鼠和SD大鼠建立肺纤维化模型，并在肺泡上皮细胞和肺成纤维细胞上分别构建EMT和FMD模型，在整体，细胞和分子水平探讨Nrf2调节EMT的作用以及自噬调节FMD的分子机制。结果发现，Nrf2通过抑制转录因子snail和Numb蛋白的表达，减轻EMT的程度。进一步研究发现，AMPK/FoxO3a通路可通过激活自噬抑制成纤维细胞的分化减轻FMD，从而调节肺纤维化的发生发展。以上研究结果提示Nrf2可以通过抑制snail和Numb减少PF中EMT的发生，而成纤维细胞中活化的自噬可以减轻FMD的程度，进一步阐明了肺纤维化的发病机制，为临床防治肺纤维化提供新思路和新方法。