Ozone Alters the Distribution of Beta(1) Integrins in Cultured Primate Bronchial Epithelial Cells

The effects of 0.5 ppm ozone exposure for 6 h on the synthesis and distribution of beta(1) integrins were examined in bronchial epithelial cells cultured at an air-cell interface. Ozone exposure damaged cilia and caused significant cell loss. Immunocytochemical localization and quantification of the beta(1) subunit in the remaining attached cells using scanning laser cytometry demonstrated time-dependent changes in beta(1) distribution in response to ozone. Although no changes were detected immediately after exposure, beta(1) immunoreactivity increased 23 +/- 5% and 66 +/- 6% at 6 and 24 h, respectively. The increased immunostaining was localized at the apical surfaces and, to a lesser extent, at cell-cell contacts of cultured cells. Furthermore, integrin redistribution was not due to increased messenger RNA (mRNA) levels and protein synthesis because levels of beta(1) mRNA and newly synthesized beta(1) protein did not change after ozone exposure. However, immunoprecipitation analysis of beta(1) integrins in lysates from equal numbers of cells showed that ozone-exposed cells contained 90 +/- 15% more total beta(1) subunit at 24 h after exposure. In addition, our results demonstrated the presence of the alpha(5)beta(1) integrin complex in bronchial epithelial cells and that the detergent-soluble amount of its associated beta(1) subunit increased 60 +/- 10% in lysates of ozone-exposed cells. In conclusion, ozone altered cellular distribution of beta(1) integrins in the remaining attached cells subsequent to cell injury and loss. The changes in beta(1) distribution might be due to increased detergent extractibility of beta(1) integrins rather than a real increase in the synthesis of beta(1) integrins.