Polycyclic aromatic hydrocarbons within airborne particulate matter (PM2.5) produced DNA bulky stable adducts in a human lung cell coculture model

To extend current knowledge on the underlying mechanisms of air pollution particulate matter (PM_2.5)‐induced human lung toxicity, the metabolic activation of polycyclic aromatic hydrocarbons (PAH) within PM_2.5 and PAH–DNA bulky stable adduct patterns in human alveolar macrophage (AM) and/or human lung epithelial L132 cells in mono‐ and cocultures were studied. In the coculture system, only human AM were exposed to air pollution PM_2.5, unlike L132 cells. Particles, inorganic fraction and positive controls [i.e. TiO₂, thermally desorbed PM (dPM) and benzo[a]pyrene, B[a]P, respectively] were included in the experimental design. Cytochrome P450 (CYP) 1A1 gene expression, CYP1A1 catalytic activity and PAH–DNA bulky stable adducts were studied after 24, 48 and/or 72 h. Relatively low doses of PAH within PM_2.5 induced CYP1A1 gene expression and CYP1A1 catalytic activity in human AM and, thereafter, PAH–DNA bulky stable adduct formation. Adduct spots in PM_2.5‐exposed human AM were higher than those in dPM‐exposed ones, thereby showing the incomplete removal of PAH by thermal desorption. PAH within air pollution PM_2.5 induced CYP1A1 gene expression but not CYP1A1 catalytic activity in L132 cells. However, despite the absence of PAH–DNA bulky stable adduct in L132 cells from human AM/L132 cell cocultures exposed to dPM_2.5 or PM_2.5, reliable quantifiable PAH–DNA bulky stable adducts were observed in L132 cells from human AM/L132 cell coculture exposed to B[a]P. Taken together, these results support the exertion of genotoxicity of highly reactive B[a]P‐derived metabolites produced within human AM not only in primary target human AM, but also in secondary target L132 cells. Copyright © 2011 John Wiley & Sons, Ltd.