PFOS and GenX Induce Mitochondrial Toxicity and Differentially Alter Respiratory Complex Activities in Liver and Brain

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants associated with adverse health effects, yet the mitochondrial consequences of exposure to individual PFAS and their mixtures remain incompletely understood. This study investigated the individual and combined effects of perfluorooctanesulfonic acid (PFOS) and hexafluoropropylene oxide dimer acid (GenX) on mitochondrial respiratory complex activities under acute, sub-chronic, and chronic exposure conditions. Acute effects were evaluated using isolated mouse liver and brain mitochondria, while repeated exposure was assessed in mice treated with PFOS, GenX, or their combination at 0.2, 2, and 10 mg/kg body weight for 1 month or 0.2 mg/kg for 5 months. PFAS distribution in plasma and brain tissues, mitochondrial oxidative phosphorylation (OXPHOS) protein expression, and predicted interactions with mitochondrial Complexes III and IV were also examined. Acute exposure inhibited Complex III and IV activities, with combined treatment generally producing greater inhibition than either compound alone. Following sub-chronic exposure, mitochondrial responses varied according to dose, treatment, and tissue, with more pronounced reductions in liver complex activities and comparatively limited changes in brain enzyme activities. Chronic low-dose exposure altered selected brain mitochondrial complex activities, while PFAS measurements revealed differences in plasma concentration and distribution across brain regions. OXPHOS protein expression also varied across brain regions and exposure conditions. Molecular docking indicated distinct predicted interaction patterns, with PFOS generally exhibiting more favorable scores at Complex III binding sites and GenX at selected Complex IV regions. Overall, these findings demonstrate exposure-dependent and tissue-specific mitochondrial responses to PFOS and GenX and highlight the importance of evaluating combined PFAS exposure across multiple exposure durations.