Association of chronic alcohol consumption and increased susceptibility to and pathogenic effects of pulmonary infection with respiratory syncytial virus in mice

Chronic alcohol abuse by human beings has been shown to be associated with increased susceptibility to pulmonary infections and severity of inflammatory responses associated with pulmonary infection. On the basis of the higher likelihood of exposure to respiratory viruses, people who abuse alcohol would logically be susceptible to respiratory viral infections. To test this hypothesis, mice were provided alcohol in drinking water for 13–16 weeks with the Meadows–Cook protocol and infected intranasally with respiratory syncytial virus. At various times after infection, severity of infection was determined by evaluation of cellular and cytokine composition of bronchoalveolar lavage fluid (BALF) and histologic evaluation of inflammation. Infection was associated with neutrophil infiltration in both groups, but the proportion and number of neutrophils in BALF were significantly greater in the alcohol consumption group than in the control group. Concentrations of tumor necrosis factor-α and monocyte chemoattractant protein-1 in BALF in the alcohol consumption group were increased. Interferon (IFN)-γ concentrations were lower in the alcohol consumption group at later times of infection. Pulmonary inflammation was cleared by 3–5 days after infection in the control group. In contrast, pulmonary inflammation was evident in the alcohol consumption group after 7 days of infection, and some mice showed severe inflammation with hemorrhage and edema. IFN-α/β was evident in BALF at low concentrations in the alcohol consumption group for several days after infection, and increased mRNA for IFN-α/β was also evident in the alcohol consumption group. This was accompanied by the presence of virus in this group at these times of infection. Chronic alcohol consumption increased severity of pulmonary infection with a virus that naturally infects hosts by an aerosol route. Infection of mice that had consumed alcohol chronically was more severe in terms of increased proinflammatory cytokine production, inflammation, and a failure to clear the virus from the lungs.