Alcohol use disorders affect antimicrobial proteins and anti-pneumococcal activity in epithelial lining fluid...

Our overall objective was to examine whether characteristics of epithelial lining fluid (ELF) from subjects with alcohol use disorders (AUDs) obtained via bronchoalveolar lavage (BAL) contribute to their predisposition to pneumococcal pneumonia. We sought to compare the anti-pneumococcal activity of acellular human BAL from subjects with AUDs to matched controls. Further, differences in BAL lysozyme activity and lactoferrin concentrations between these two groups were examined to determine the effect of AUDs on these antimicrobial proteins.

BAL was performed in subjects with AUDs and matched controls. Acellular BAL was used at varying concentrations in an in vitro killing assay of Streptococcus pneumoniae, type 2, and the percent kill of organisms per microgram per milliliter total BAL protein was ascertained. Lysozyme activity and lactoferrin concentrations were measured in BAL from subjects and controls at measured concentrations of BAL protein.

AUD subjects (n = 15) and controls (n = 10) were enrolled in these investigations who were balanced in terms of smoking history. Using a mixed effect model, across the range of BAL protein concentrations, killing of pneumococcus tended to be less potent with BAL fluid from AUD subjects. Additionally, lysozyme activity and lactoferrin concentrations were significantly lower in the AUD group.

The predisposition for pneumococcal pneumonia among those with AUDs may be in part mediated through effects of alcohol on substances within ELF that include antimicrobial proteins. Clarifying the composition and activity of ELF antimicrobial proteins in the setting of AUDs via investigations with human BAL fluid can help establish their contribution to the susceptibility for pulmonary infections in these individuals.