Fine environmental particulate engenders alterations in human lung epithelial A549 cells

Particulate matter (PM), a component of urban air pollution that derives primarily from the combustion of fossil fuels, is responsible for a number of health effects in humans. Recent studies have demonstrated that the fine particles (PM2.5) present in high numbers in PM samples can be more harmful than larger particles, since they are more efficiently retained in the peripheral lung. In the present study, we have investigated the biological effects of PM2.5 on human lung epithelial cell line A549. Morphological analysis performed by immunofluorescence and electron microscopy showed that fine particles interact with the cell surface, where they induce evident alterations and, subsequently, are internalized in the cytoplasm. Cytoskeletal components, in particular microfilaments and microtubules, cause modifications upon challenge with PM2.5. Of interest, an early cell response to the fine particulate is an increase of reactive oxygen species content, which can account for the observed cytoskeletal changes and the production of proinflammatory cytokines in A549 cells. In particular, exposure to PM2.5 promoted a dose- and time-dependent release of TNF-α and IL-6 in the cell medium.