Ambient PM2.5 causes lung injuries and coupled energy metabolic disorder

Abstract

Ambient fine particulate matter (PM2.5) is a challenge to public health worldwide. Although increasing numbers of recent epidemiological studies have emphasized the critical role of PM2.5 in promoting respiratory diseases, the precise mechanism behind PM2.5-mediated lung obstruction remains obscure. In the present study, we analyzed lung structure and function and further investigated mitochondrial morphology and transcription-modulated energy metabolism in mice following PM2.5 aspiration. The results showed that PM2.5 exposure reduced pulmonary function and induced severe pathological alterations, including alveolar endothelial disruption and airway obstruction. Based on ultrastructural observations, we also found mitochondrial vacuolation and mitochondrial membrane rupture in alveolar type II epithelial cells. Importantly, the abnormality of mitochondrial structure was coupled with energy metabolism disorders, as evidenced by the decrease in ATP levels, the accumulation of pyruvate and lactate content, and the altered transcription of related genes. Moreover, the reduction in mitochondrial markers, including PGC-1α, NRF-1, and TFAM, were involved in mitochondrial dysfunction. These findings suggest that energy metabolic disorders and mitochondrial dysfunction may be the important contributors to pulmonary injuries in response to PM2.5 exposure, indicating possible targets for protection and therapy in polluted areas.