Fas/FasL-mediated apoptosis in perinatal murine lungs

Open Access
Publisher Website
Google Scholar
Abstract
Postcanalicular lung development is characterized by a time-specific increase in alveolar epithelial type II cell apoptosis. We have previously demonstrated that, in fetal rabbits, developmental type II cell apoptosis coincides with transient upregulation of the cell death regulator Fas ligand (FasL). The aims of this study were 1) to determine the spatiotemporal patterns of pulmonary apoptosis and Fas/FasL gene expression in the murine model [embryonic day 17 (E17) through postnatal day 5 (P5)], and 2) to investigate the functional involvement of the Fas/FasL system by determining the effect of Fas activation and inhibition on perinatal pulmonary apoptosis. The apoptotic activity of alveolar epithelial type II cells, determined by combined TUNEL labeling and anti-surfactant protein B immunohistochemistry, showed a dramatic increase during the perinatal transition (type II cell apoptotic index lpr mice remained unchanged. Conversely, administration of a caspase inhibitor to newborn mice (P1) resulted in marked diminution of pulmonary apoptotic activity. These combined findings strongly implicate the Fas/FasL system as a critical regulator of perinatal type II cell apoptosis. The developmental time dependence of apoptosis-related events in the murine model should facilitate investigations of the regulation of perinatal pulmonary apoptotic gene expression.