Impact of fine particulate matter on liver injury: evidence from human, mice and cells

Background: A recently discovered risk factor for chronic liver disease is ambient fine particulate matter (PM2.5). Our research aims to elucidate the effects of PM2.5 on liver injury and the potential molecular mechanisms. Methods and results: A population-based longitudinal study involving 102,918 participants from 15 Chinese cities, using linear mixed-effect models, found that abnormal alterations in liver function were significantly associated with long-term exposure to PM2.5. The serum levels of alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, direct bilirubin, and triglyceride increased by 2.05%, 2.04%, 0.58%, 2.99%, and 1.46% with each 10 mu g/m3 increase in PM2.5. In contrast, the serum levels of total protein, albumin, and prealbumin decreased by 0.27%, 0.48%, and 2.42%, respectively. Mice underwent chronic inhalation exposure to PM2.5 experienced hepatic inflammation, steatosis and fibrosis. In vitro experiments found that hepatocytes experienced an inflammatory response and lipid metabolic dysregulation due to PM2.5, which also activated hepatic stellate cells. The down -regulation and mis-localization of polarity protein Par3 mediated PM2.5-induced liver injury. Conclusions: PM2.5 exposure induced liver injury, mainly characterized by steatosis and fibrosis. The downregulation and mis-localization of Par3 were important mechanisms of liver injury induced by PM2.5.