Effects of ozone exposure on nuclear factor-κB activation and tumor necrosis factor-α expression in human nasal epithelial cells

In this study we investigated a possible mechanism of the human airway inflammatory response to inhaled ozone (O-3). Cultures of human nasal epithelial (HNE) cells, initiated from excised nasal turbinates and grown on collagen-coated Transwell (R) tissue culture inserts, were exposed to 120, 240, or 500 ppb O-3 for 3 h. An electron spin resonance (ESR) signal that changed with time suggested free radical production in HNE cells exposed to O-3. Nuclear protein extracts were analyzed for the activated transcription factor NF-kappaB by electrophoretic mobility-shift assay (EMSA), and showed a small dose-response activation of NF-kappaB that coincided with O-3-induced free radical production. Basal media were analyzed for the presence of tumor necrosis factor-alpha (TNF-alpha) using the enzyme-linked immunosorbent assay (ELISA). In cultures exposed to 120 ppb O-3, the mean TNF-a concentration was not significantly different from those exposed to air. However, exposure to 240 and 500 ppb O-3 significantly increased mean TNF-alpha expression, relative to controls, 16 h after exposure. These results support the hypothesis that the human airway epithelium plays a role in directing the inflammatory response to inhaled O-3 via free radical-mediated NF-kappaB activation.