PM2.5 promotes Drp1-mediated mitophagy to induce hepatic stellate cell activation and hepatic fibrosis via regulating miR-411

Background: Particulate matter <= 2.5 mu m (PM2.5) is a type of environmental agent associated with air pollution, which induces hepatic fibrosis. However, the function and mechanism of PM2.5 on hepatic stellate cell (HSC) proliferation and fibrosis remain largely unknown.Methods: Human HSC line (LX-2) and murine HSCs were exposed to various doses of PM2.5. microRNA (miR)-411 expression was detected via quantitative reverse transcription polymerase chain reaction (qRT-PCR). Cell proliferation, fibrosis, mitochondrial dynamics dysfunction and mitophagy were determined via cell counting kit-8 (CCK-8), qRT-PCR, Western blotting and immunofluorescence.Results: PM2.5 facilitated HSC proliferation and fibrosis via increasing the levels of ACTA2, Collagen 1, TIMP1 and TGF-beta 1. PM2.5 reduced miR-411 expression, and contributed to mitochondrial dynamics dysfunction via increasing Drp1 and decreasing OPA1, TOM20 and PGC-1 alpha levels. PM2.5 promoted mitophagy by upregulating the levels of Beclin-1, LC3II/I, PINK1 and Parkin. miR-411 overexpression or autophagy blockage using 3-methyladenine (3-MA) relieved PM2.5-mediated cell proliferation and fibrosis-associated factor expression in HSCs. Drp1 was targeted by miR-411. miR-411 mitigated PM2.5-induced mitophagy via targeting Drp1. Drp1 overexpression abolished the inhibitory role of miR-411 in cell proliferation and fibrosis-associated factor levels in HSCs.Conclusion: PM2.5 induced HSC activation and fibrosis via promoting Drp1-mediated mitophagy by decreasing miR-411, thereby causing liver fibrosis.