Antioxidant properties of guinea pig tracheal epithelial cells in vitro

Guinea pig tracheal epithelial (GPTE) cells in primary air/liquid interface culture were exposed to H2O2, and the rate of H2O2 consumption by apical and basolateral surfaces was measured. GPTE cells had potent H2O2 scavenging ability, with faster consumption of H2O2 from the apical surface. Inhibition of catalase (Cat) with sodium azide (NaAz) significantly attenuated the ability of GPTE cells to remove higher concentrations of H2O2. Depletion of reduced glutathione, the substrate for glutathione peroxidase (GPO), with DL-buthionine-[S,R]-sulfoximine (BSO) did not affect consumption of H2O2. Dissolution of mucus from the cells reduced scavenging activity of the cultures and basement membrane/extracellular matrix material (BM/ECM) deposited by the cells demonstrated significant H2O2-scavenging activity. The results suggest that GPTE cells retain antioxidant capability in vitro when cultured in an air/liquid interface. This capacity to scavenge H2O2 appears to rely on Cat, as well as on mucus and BM/ECM material. However, a significant amount of H2O2 scavenging appears to depend on other, yet unidentified, antioxidant system(s).