World Trade Center (WTC) dust exposure in mice is associated with inflammation, oxidative stress and epigenetic changes in the lung

Exposure to World Trade Center (WTC) dust has been linked to respiratory disease in humans. In the present studies we developed a rodent model of WTC dust exposure to analyze lung oxidative stress and inflammation, with the goal of elucidating potential epigenetic mechanisms underlying these responses. Exposure of mice to WTC dust (20 μg, i.t.) was associated with upregulation of heme oxygenase-1 and cyclooxygenase-2 within 3 days, a response which persisted for at least 21 days. Whereas matrix metalloproteinase was upregulated 7 days post-WTC dust exposure, IL-6RA1 was increased at 21 days; conversely, expression of mannose receptor, a scavenger receptor important in particle clearance, decreased. After WTC dust exposure, increases in methylation of histone H3 lysine K4 at 3 days, lysine K27 at 7 days and lysine K36, were observed in the lung, along with hypermethylation of Line-1 element at 21 days. Alterations in pulmonary mechanics were also observed following WTC dust exposure. Thus, 3 days post-exposure, lung resistance and tissue damping were decreased. In contrast at 21 days, lung resistance, central airway resistance, tissue damping and tissue elastance were increased. These data demonstrate that WTC dust-induced inflammation and oxidative stress are associated with epigenetic modifications in the lung and altered pulmonary mechanics. These changes may contribute to the development of WTC dust pathologies.