Adverse impact of ambient PM2.5 on expression and trafficking of surfactant protein A through reactive oxygen species damage to lamellar bodies

•The expression of SP-A showed a tendency to first rise then descend in response to the increase of PM2.5 concentration.•With the increase of the concentration of PM2.5, ROS production and inflammation infiltration are substantially accumulated.•The LBs responsible for the transport and storage of SP-A protein was severely damaged under the high dose of PM2.5 exposure.•The damage under the high concentration of PM2.5 exposure were well rescued by NAC as an oxidant inhibitor to antagonize ROS. Particulate matter with a diameter of less than 2.5 μm (PM2.5) easily deposits on lung alveoli and degrades human health. Surfactant protein A (SP-A) is the most abundant pulmonary surfactant protein stored in lamellar bodies (LBs) of alveolar epithelial type II cells. The impacts of PM2.5 on SP-A are multifaceted and intractable, and the underlying mechanism remains unclear. In this study, the expression and distribution of SP-A in Balb/c mice and A549 cells under PM2.5 exposure were investigated. The results showed that the low and medium concentration of PM2.5 gradually enhanced SP-A protein and mRNA expression, whereas the high concentration of PM2.5 conspicuously decreased SP-A protein but not its mRNA compared with the control. The trafficking of SP-A to LBs was gradually disturbed, and concomitantly, the lesions of LBs responsible for the transport and storage of SP-A protein were exacerbated with increased PM2.5 concentration. Reactive oxygen species production abundantly increased upon PM2.5 exposure, and it was antagonized by the oxidant inhibitor N-acetylcysteine. Subsequently, the injured LBs and the decrease in SP-A expression under exposure to the high concentration of PM2.5 were well rescued. The present study provides a new perspective to investigate the adverse effects of PM2.5 or diesel exhaust particles on other proteins transported to and stored in LBs.