The effects of chronic alcohol abuse on pulmonary glutathione homeostasis

The incidence and severity of the acute respiratory distress syndrome (ARDS) is increased in critically ill patients with a prior history of chronic alcohol abuse; however, the specific mechanisms responsible for this association are unknown. Recently, we determined that chronic ethanol ingestion in rats decreased the alveolar epithelial lining fluid (ELF) concentration of the antioxidant glutathione (GSH), which is a characteristic finding in patients with ARDS. However, the effects of chronic alcohol abuse on the human alveolar epithelium are essentially unknown. Therefore, as a first step we asked if chronic alcohol abuse, independent of other comorbid conditions, decreases the concentration of GSH in the human lung. We determined that otherwise healthy chronic alcoholics had significantly decreased ELF concentrations of GSH compared with nonalcoholic control subjects (79 micromol [48 to 118 micromol] versus 576 micromol [493 to 728 mmol], p < 0.001). Furthermore, the percentage of GSH in the oxidized form was higher in the chronic alcoholics (9.8% [2.2 to 14.8%] versus 2.8% [0.4 to 4.0%] p = 0.05), indicative of increased utilization of GSH. This is the first report that chronic alcohol abuse alters GSH homeostasis in the human lung, and suggests a potential mechanism by which chronic alcohol abuse predisposes susceptible patients to develop ARDS.