Mixed leachate from polylactic acid food containers exacerbates NAFLD in obese mice at environmentally relevant levels: cAMP-dependent acid lipolysis mechanism.

Although high-dose independent exposure to commercial microplastics or plastic additives triggers nonalcoholic fatty liver disease (NAFLD), the hepatotoxic effects of the mixed leachate from single-use food containers (SUFCs) at environmentally relevant concentrations remain poorly elucidated. In this study, mice were chronically exposed to the mixed leachate extracted from polylactic acid (PLA)-based SUFCs under realistic exposure scenarios. We found that PLA-SUFC leachate exacerbates hepatic lipid accumulation and promotes NAFLD progression in obese mice, while exerting negligible effects on normal-weight mice. Mechanistically, these effects are primarily mediated by enhanced hepatic uptake of free fatty acids (FFAs) along the epididymal white adipose tissue (eWAT)-liver axis. Remarkably, FFA liberation from eWAT adipocytes relies on lysosomal acid lipolysis rather than canonical cytoplasmic neutral lipolysis. Single-nucleus RNA sequencing and functional assays demonstrated that mixed leachate exposure increases cyclic adenosine monophosphate (cAMP) levels via inhibiting the insulin-like growth factor 1 (IGF1)-phosphatidylinositol 3-kinase (PI3K) pathway and activating adenylate cyclase 8. Elevated cAMP specifically upregulates lysosomal acid lipase activity via the exchange protein activated by cAMP (EPAC)/forkhead box O1 (FoxO1) pathway without altering adipose triglyceride lipase levels, thereby promoting lysosomal acid lipolysis in adipocytes. Collectively, these findings suggest that long-term consumption of PLA-SUFC might increase NAFLD risk in obese individuals, and further reveal cAMP-dependent acid lipolysis as a novel mechanism of NAFLD.