Mechanistic Insights into Nrf2 Activation and Oxidative Stress Responses of Per- and Polyfluoroalkyl Substances (PFAS) in Human Keratinocytes.

Per- and polyfluoroalkyl substances (PFAS) are widely used in consumer products for their hydrophobic and chemical stability, yet their dermatotoxicological effects remain underexplored. This study investigated the ability of representative PFAS (PFBS, PFBA, PFHpA, PFOA, PFNA, PFDA, 4:2 FTOH, and 6:2 FTOH) to activate the Nrf2-Keap1-ARE signaling pathway and induce oxidative stress in human keratinocytes. Results revealed that PFOA and PFHpA tested positive for the KeratinoSens™ assay, while PFNA showed borderline activity. PFNA and 6:2 FTOH produced the highest ROS increases at sub-cytotoxic levels, decreasing at higher doses, suggesting cytotoxic stress. PFHpA, PFOA, PFBS, PFBA, 4:2 FTOH and PFDA induced relatively minor fluctuations in ROS across all concentrations. Although previously reported as negative in the murine Local Lymph Node Assay (LLNA), PFOA tested positive in both KeratinoSens™ and ROS assays, indicating activation of oxidative stress-driven cellular pathways distinct from classical immune sensitization mechanisms. In silico prediction failed to capture these effects, underscoring current limitations of computational toxicology for PFAS. These findings suggest that PFAS-induced oxidative stress may compromise skin barrier function and inflammatory signaling, with implications for dermatological disorders and consumer safety. These results highlight Nrf2-mediated redox signaling as a mechanistically relevant target for evaluating PFAS-induced dermatotoxicity and support the integration of pathway-based in vitro assays into PFAS risk assessment.