Inhaled particulate matter causes expression of nuclear factor (NF)-kappa B-related genes and oxidant-dependent NF-kappa B activation in vitro

High levels of ambient air pollution are associated with exacerbation of as thma and respiratory morbidity, yet little is known concerning the mechanis ms of inflammation and toxicity by components of inhaled particulate matter (PM), Brief inhalation of PM2.5 (particles of an aerodynamic diameter of < 2.5 microns) (300 mu g/m(3) air for 6 h followed by a period of 24 h in cle an air) by either C3H/HeJ or C57/BL6 mice caused significant (P less than o r equal to 0.05) increases in steady-state messenger RNA (mRNA) levels of a number of nuclear factor (NF)-kappa B-associated and/or -regulated genes, including tumor necrosis factor-alpha and -beta, interleukin-6, interferon- gamma, and transforming growth factor-beta. Lung mRNA levels of lymphotoxin -beta and macrophage migration inhibitory factor were unchanged. In murine C10 alveolar cells and an NF-kappa B-luciferase reporter cell line, exposur e to PM2.5 at noncytotoxic concentrations resulted in increases in transcri ptional activation of NF-kappa B-dependent gene expression which were inhib ited in the presence of catalase. Early and persistent increases in intrace llular oxidants, as measured by flow cytometry and cell imaging using the o xidant probe 2'-7'-dichlorofluoroscin diacetate, were observed in epithelia l cells exposed to PM2.5, and ultrafine carbon black particles. Studies her e are the first to show NF-kappa B-related inflammatory and cytokine gene e xpression after inhalation of PM2.5 and oxidant-dependent induction of NF-k appa B activity by PM2.5 in pulmonary epithelial cells.