Abstract:
In this study, we investigated a possible mechanism of the human airway inflammatory response to inhaled ozone (O3). Cultures of human nasal epithelial (HNE) cells were initiated from excised nasal turbinates on collagen-coated Transwellà tissue culture inserts and exposed to 120, 240, or 500 ppb O3 for 3 hours. Free radical production in HNE cells exposed to O3 was confirmed by the presence of an electron spin resonance (ESR) signal that changed with time. Nuclear protein extracts were analyzed for the activated transcription factor NF-kB by electrophoretic mobility shift assay (EMSA), showing a slight dose-response activation of NF-kB that coincided with O3 induced free radical production. Basal media was then collected for tumor necrosis factor-alpha (TNF-a) quantification by enzyme-linked immunosorbent assay (ELISA). Mean TNF-a concentration in cultures exposed to 120 ppb O3 (10.34 + 1.32 pg/ml) was not significantly different than in those exposed to air (11.01 + 1.10/g/ml). However, exposure to 240 and 500 ppb O3 significantly increased mean TNF-a expression relative to controls 16h after exposure by 75% (from 34.25 + 4.39 pg/ml to 59.77 + 8.72 pg/ml) and 48% (from 36.93 + 7.72 pg/ml to 54.66 + 11.49 pg/ml), respectively. These results support the hypothesis that the human airway epithelium plays a role in directing the inflammatory response to inhaled O3 via free radical-mediated NF-kB.