Intratracheal perfluorooctane sulfonate induces pulmonary injury via TLRs signaling and disrupts sex steroidogenesis through systemic translocation.

Numerous studies have reported the widespread presence of per- and polyfluoroalkyl substances (PFASs) in both indoor and outdoor air, yet the inhalation toxicity of these substances remains poorly understood. This research aims to investigate the lung and reproductive toxicity associated with respiratory exposure to perfluorooctane sulfonate (PFOS), particularly focusing on low doses of PFOS which were even lower than the human internal exposure levels. By intratracheal instillation of low (5 μg/kg), medium (25 μg/kg), and high (625 μg/kg) doses of PFOS, we demonstrated that repeated inhalation of PFOS once a week for four consecutive weeks can directly impaired lung function in mice, inducing pulmonary inflammation and fibrotic damage. Even partial inflammatory injury was observed in the 5 μg/kg group. By inhibiting Toll-like receptors (TLRs) 2 and 4 in BEAS-2B cells and RAW264.7 cells, we revealed the crucial role of TLRs signaling pathway in PFOS-induced lung injury. Quantitative UPLC-MS/MS analysis confirmed systemic distribution of PFOS, with blood concentrations reaching 170.58 ng/mL at 25 μg/kg exposure (12.28 % bioavailability). Crucially, this systemic translocation correlated with disrupted steroidogenesis, as evidenced by significant suppression of sex hormone synthesis in mice. Even at extremely low doses, such toxic effects have been observed and further confirmed in vitro models of Leydig cells and ovarian granulosa cells. This study is the first to clarify that inhalation of PFOS not only causes lung injury through TLRs signaling pathways but also leads to reproductive toxicity, providing novel insights into the health risks associated with emerging contaminants.