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BACKGROUND: Human exposure to ozone (O-3) results in pulmonary function decrements and airway inflammation. The mechanisms underlying these adverse effects remain unclear. Epidermal growth factor receptor (EGFR) plays an important role in the pathogenesis of lung inflammation.

OBJECTIVE: We examined the role of EGFR activation in O-3-induced expression of the chemokine interleukin 8 (IL-8) in human bronchial epithelial cells (HBEC).

METHODS: We detected phosphorylated EGFR using immunoblotting. EGFR dimeriza-tion was examined through cross-linking reaction and immunoblotting, and levels of IL-8 protein were measured using ELISA.

RESULTS: Exposure to O-3 (0.25-1.0 ppm) induced rapid and marked increase in EGFR phosphorylation at the autophosphorylation site Y1068 and the transphosphorylation site Y845, implicating the involvement of Src kinase. Further investigation showed that O-3 stimulation induced phosphorylation of Src at Y416, indicative of Src activation. Pharmacological inhibition of Src kinase activity abrogated O-3-induced EGFR phosphorylation at tyrosines 1068 and 845. Moreover, pretreatment of BEAS-2B cells with inhibitor of either EGFR or Src kinase activities significantly blocked O-3-induced IL-8 expression.

CONCLUSION: O-3 exposure increased IL-8 expression through Src-mediated EGFR transactivation in HBEC.