Macrophage Raptor Deficiency-Induced Lysosome Dysfunction Exacerbates Nonalcoholic Steatohepatitis

作者：Liu, Wenli; Ye, Chenji; Cheng, Qian; Zhang, Xuejiao; Yao, Liu; Li, Qi; Huang, Jing; Liu, Yajin; Zou, Zhengsheng; Wang, Hua; Yan, Jun; Zhu, Yi; Wang, Chunjiong^*; Ai, Ding^*

来源：Cellular and Molecular Gastroenterology and Hepatology, 2019, 7(1): 211-231.

DOI：10.1016/j.jcmgh.2018.09.011

• mTORC1
• NASH
• Lysosome
• Drp1

BACKGROUND & AIMS: Nonalcoholic steatohepatitis (NASH) is an increasingly prevalent nonalcoholic fatty liver disease, characterized by inflammatory cell infiltration and hepatocellular damage. Mammalian target of rapamycin complex 1 (mTORC1) has been investigated extensively in the context of cancer, including hepatocellular carcinoma. However, the role of mTORC1 in NASH remains largely unknown. @@@ METHODS: mTORC1 activity in macrophages in human mild and severe NASH liver was compared. Mice with macrophage-specific deletion of the regulatory-associated protein of mTOR (Raptor) subunit and littermate controls were fed a high-fructose, palmitate, and cholesterol diet for 24 weeks or a methionine- and choline-deficient diet for 4 weeks to develop NASH. @@@ RESULTS: We report that in human beings bearing NASH, macrophage mTORC1 activity was lower in livers experiencing severe vs mild NASH liver. Moreover, macrophage mTORC1 disruption exacerbated the inflammatory response in 2 diet-induced NASH mouse models. Mechanistically, in response to apoptotic hepatocytes (AHs), macrophage polarization toward a M2 anti-inflammatory phenotype was inhibited in Raptor-deficient macrophages. During the digestion of AHs, macrophage mTORC1 was activated and coupled with dynamin-related protein 1 to facilitate the latter's phosphorylation, leading to mitochondrial fission-mediated calcium release. Ionomycin or A23187, calcium ionophores, prevented Raptor deficiency-mediated failure of lysosome acidification and subsequent lipolysis. Blocking dynamin-related protein 1-dependent mitochondria fission impaired lysosome function, resulting in reduced production of anti-inflammatory factors such as interleukins 10 and 13. @@@ CONCLUSIONS: Persistent mTORC1 deficiency in macrophages contributes to the progression of NASH by causing lysosome dysfunction and subsequently attenuating anti-inflammatory M2-like response in macrophages during clearance of AHs.

• 出版日期2019
• 单位天津市第一中心医院; 中国人民解放军第三０二医院; 天津医科大学; 安徽医科大学