THE INTERACTION OF ASBESTOS AND NEUTROPHILS INJURES CULTURED HUMAN PULMONARY EPITHELIAL-CELLS - ROLE OF HYDROGEN-PEROXIDE

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  • 1 November 1989
    • journal article
    • research article
    • Vol. 114  (5) , 604-612
Abstract
Asbestos exposure causes diffuse interstitial pulmonary fibrosis. Since alveolar epithelial cell injury is hypothesized to preceded the fibrotic responses in asbestosis, we investigated whether asbestos, either alone or in conjunction with neutrophils (PMNs), injured cultured human pulmonary epithelial cells (HPECs). HPEC cytotoxicity was assessed with a standard 51chromium release assay after a 16-hour incubation with asbestos and PMNs. Negligible HPEC cytoxicity was observed after incubation with either amosite asbestos (500 .mu.g/ml) or PMNs alone in serum-free media. However, incubation with both asbestos and PMNs caused significant HPEC injury, which was asbestos dose-dependent; causing 25% .+-. 4% detachment and 52% .+-. 8% 51chromium release with 500 .mu.g/ml asbestos. The cytotoxic effect of asbestos plus PMNs were nearly completely attenuated with serum (20%) or catalase (100 .mu.g/ml) but were not prevented with scavengers of superoxide anion, hydroxyl radical, or hypochlorous acid. A role for hydrogen peroxide (H2O2) in mediating HPEC injury was also suggested by the demonstration of asbestos-induced generation of H2O2 by PMNs. Furthermore, H2O2 alone (10-4mol/L) caused significant HPEC damage. Intimate contact between asbestos-activated PMNs and HPECs was a necessary requirement for PMN-mediated HPEC cytotoxicity. These data suggest that pulmonary epithelial cell injury is mediated in part by H2O2 release from asbestos-activated PMNs as well as intimate contact between the epithelial cell, PMNs and asbestos.