Isoprene-derived secondary organic aerosol induces the expression of oxidative stress response genes in human lung cells

Abstract

Atmospheric oxidation of isoprene in the presence of acidic sulfate aerosol leads to secondary organic aerosol (SOA) that substantially contributes to the mass of outdoor fine particulate matter (PM2.5). The potential adverse health effects resulting from exposure to this PM type are largely unknown. Isoprene-derived epoxides, isoprene epoxydiols (IEPOX) and methacrylic acid epoxide (MAE), have recently been identified as key gaseous intermediates leading to isoprene SOA formation through acid-catalyzed multiphase chemistry. Altered expression of oxidative stress-Associated genes was assessed from exposure to laboratory-generated IEPOX-and MAE-derived SOA in an in vitro model of human airway epithelial cells (BEAS-2B). Exposure to SOA filter extracts is associated with an increased level of expression of oxidative stress response genes in human lung cells under noncytotoxic conditions, with MAE-derived SOA extracts showing greater potency than IEPOX-derived SOA extracts. Our findings highlight the importance of future work aimed at linking PM source, composition, exposure biomarkers, and health outcomes.