Comparative Immunotoxicity and Transcriptomic Profiling of Seven PFAS in THP-1 Macrophages

Per- and polyfluoroalkyl substances (PFAS) are a large class of persistent synthetic chemicals widely used across industrial and consumer products. While legacy PFAS, such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), have been extensively studied and linked to immunotoxicity, far less is known about the immune-related hazards of newer-generation alternatives. In this study, we systematically evaluated the immunotoxic potential of seven PFAS, including three perfluoroalkyl acids (PFOA, PFOS, PFHpS) and four (poly-)ether PFAS (PFESA BP2, PFESA BP1, DOPFLCA, 8:2 Cl-PFESA) using a THP-1 macrophage model with dose-range exposures for up to 72 hours. Despite an equipotent dosing scheme, the molecular responses to different PFAS congeners were distinct. RNA sequencing revealed that PFOA and PFHpS, but not PFOS, elicited a larger number of differentially expressed genes than ether PFAS. We observed that the absolute PFAS concentration correlated more strongly with the number of DEGs than viability-based potency, suggesting differences in the underlying mechanisms of toxicity. The shared transcriptional signature highlighted PPAR signalling at the core of molecular responses to both legacy and newer-generation alternatives, while an adverse outcome pathway analysis revealed functional differences between the congeners. Together, these findings reveal compound-specific and structure-related differences in immunomodulatory potential among PFAS, with clear distinction by PFAS type. This study provides comprehensive comparative insights to inform hazard evaluation and support the development of safer PFAS alternatives.