Hydrogen peroxide induces DNA single strand breaks in respiratory epithelial cells

The respiratory epithelium is often exposed to oxidant gases, including ozone from photochemical smog and toxic oxygen metabolites released from neutrophils recruited in conditions of airway inflammation. We evaluated DNA single strand break formation by alkaline elution as a measure of oxidant-induced DNA damage to bronchial epithelial cells. Human AdenoSV-40-transformed bronchial epithelial cells (BEAS), subclone R1.4 or nonhuman primate bronchial epithelial cells were cultured in growth factor supplemented Ham's F12 medium on polycarbonate filters. DNA was labeled by incubation with [³H]thymidine. Cells were incubated for 1 h in HBSS or HBSS and increasing concentrations of hydrogen peroxide (H₂O₂). Cells incubated in H₂O₂ demonstrated dose-dependent increases in strand break formation, and BEAS cells were more sensitive to H₂O₂-induced injury than primary bronchial epithelial cells. The addition of catalase or preincubation of cells with the iron chelator desferoxamine prevented H₂O₂-induced strand breakage. DNA strand break formation may be an important mechanism of oxidant injury in respiratory epithelial cells.This work was supported by NIEHS grant ES-00628 and California Primate Research Center Base grant. Portions of this work were presented at the American Thoracic Society annual meeting, May 1992, Miami, Florida.