Effects of chronic alcohol abuse on alveolar epithelial barrier function and glutathione homeostasis

Background: An association between the development and severity of the acute respiratory distress syndrome has been described in individuals who abuse alcohol chronically, possibly through a mechanism involving the deficiency of pulmonary glutathione. In a rodent model of chronic alcohol abuse, this antioxidant contributes to the maintenance of alveolar-capillary membrane integrity. We postulated that humans who chronically abuse alcohol will have similar alterations in alveolar-capillary barrier function. Methods: Bronchoalveolar lavage was performed in 18 healthy chronic alcoholics and 18 control subjects; total protein and glutathione concentrations were measured within the epithelial lining fluid. To examine possible protracted effects of alcohol abuse, a subset of 11 chronic alcoholic subjects underwent a second bronchoalveolar lavage after a week of abstinence. Results: Chronic alcoholic subjects had significantly elevated protein concentrations compared with controls (8.64 mug protein/ng immunoglobulin A vs. 5.91 mug protein/ng immunoglobulin A, p = 0.01). After a week of abstinence, no significant increase in either the glutathione levels or normalization of the protein concentrations in the epithelial lining fluid was demonstrable. Conclusions: Increased protein levels in the epithelial lining fluid of individuals who abuse alcohol chronically may signify abnormal alveolar epithelial barrier function that does not appear to readily reverse after a period of abstinence.