H2O2 induces apoptosis in bovine tracheal epithelial cells in vitro

Oxidants play an important role in the pathogenesis of various airway diseases. Oxidants have been shown to induce two distinct types of cell death, i.e., apoptosis and necrosis. However, whether oxidants induce apoptosis in airway epithelial cells remains unclear. To address this question, we evaluated the effect of H2O2 exposure on bovine tracheal epithelial cells cultured under different conditions. When tracheal epithelial cells were isolated and exposed to H2O2 in suspension cultures, they underwent apoptosis as demonstrated by characteristic ultrastructural changes and DNA fragmentation. Interestingly, apoptosis occurred in single cells but not in aggregated cells. In addition, apoptosis was seen in many ciliated and in fewer mucous cells. When tracheal epithelial cells were allowed to attach to the substrate and grow, they became resistant to apoptosis induced by H2O2. These results suggest that H2O2 can induce apoptosis in airway epithelial cells.