Effects of Ozone Exposure on Nuclear Factor-kappaB Activation and Tumor Necrosis Factor-alpha 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 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-alpha 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.