Long-term polystyrene nanoplastic exposure induces membrane phospholipid remodeling in fish skin-derived epithelial cells

The increasing production and use of plastic have resulted in the widespread occurrence of nanoplastics (NPs) in aquatic environments, raising concerns about their potential impacts on aquatic organisms. In this study, we investigated the cellular responses of fish skin-derived EPC epithelial cells to long-term exposure to polystyrene nanoplastics (PS-NP) and elucidated the mechanisms underlying membrane phospholipid remodeling using untargeted lipidomic analysis based on UPLC-Q-TOF-MS. EPC cells were exposed to PS-NPs for 15 days, followed by cellular, molecular, and lipidomic analyses. Long-term PS-NP exposure did not significantly alter cell viability or morphology but resulted in PS-NP accumulation within lysosomes and persistent ROS and lipid peroxidation. Untargeted lipidomic profiling revealed enrichment of the ferroptosis, glycerophospholipid metabolism, and sphingolipid metabolism pathways, accompanied by remodeling of polyunsaturated phosphatidylethanolamine (PUFA-PE) species and the overall membrane phospholipid composition. Consistent with these lipidomic changes, antioxidant and Lands cycle-related genes were upregulated, indicating ferroptosis-associated lipid remodeling rather than the initiation of ferroptotic cell death. In parallel, phosphatidylethanolamine (PE) and phosphatidylinositol (PI) were decreased, with enrichment of glycosylphosphatidylinositol (GPI)-anchor biosynthesis and autophagy pathways, suggesting potential alterations in membrane-associated homeostatic processes. These findings demonstrate that long-term PS-NP exposure induces membrane homeostatic responses through Lands cycle-mediated phospholipid remodeling, antioxidant responses, and lysosomal responses without overt cytotoxicity. This membrane-level response is not captured by conventional viability- or ROS-based endpoints, and identifies the plasma membrane lipidome as a sensitive target of prolonged, sublethal nanoplastic exposure in fish skin-derived epithelial cells.