Chronic Ethanol Exposure of Basal Cells causes Barrier Dysfunction of Differentiated Mucocilliary Monolayers

• Published in: The FASEB journal Vol. 36; no. S1
• Main Authors: Easley, Kristen F., Mehta, Ashish J., Staitieh, Bashar S., Koval, Michael
• Format: Journal Article
• Language: English
• Published: United States The Federation of American Societies for Experimental Biology 01-05-2022
• DOI: 10.1096/fasebj.2022.36.S1.R6101
• EISSN: 1530-6860
• ISSN: 0892-6638

Alcohol use disorder affects over 14 million adults and causes 88,000 deaths each year in the United States. Chronic alcohol use significantly increases people’s risk of developing lung infections and acute respiratory distress syndrome (ARDS). This increased sensitivity to injury is a condition known as alcoholic lung syndrome, and it is caused by dysfunction of the lung immune system and alveolar epithelial barrier. However, little is known about how alcohol impacts epithelial cells in the conducting airway, i.e. the trachea and bronchi, which is the first line of defense against infectious pathogens in the lungs. We hypothesize that in vitro ethanol exposure decreases barrier function of human primary bronchial epithelial cells. To test this, we dosed cells with ethanol at various timepoints: 1) during both the basal‐cell expansion and differentiation stages 2) the first 14 days of differentiation on Transwell permeable supports at air liquid interface (ALI); 3) beginning on day 14 of differentiation and continuing for 10 days. We treated cells with 10mM, 60mM or 100mM ethanol almost daily and measured barrier function by transepithelial electrical resistance (TER). We found that ethanol caused a dose‐dependent decrease in barrier function, but only in the group treated during both the expansion and differentiation stages. This suggests that chronically dosing basal cells with ethanol is required for barrier dysfunction of a fully differentiated cell monolayer. Additionally, we cultured primary airway epithelial cells isolated from healthy and alcoholic patients on Transwell permeable supports and differentiated them in vitro to determine if in vivo exposure caused long‐term changes to tight junction protein levels. It is known that the transmembrane protein junctional adhesion molecule A (JAM‐A) regulates barrier function by controlling the paracellular flow of small molecules as part of the tight junction barrier. Our results show in response to alcohol exposure, cells have lower JAM‐A protein expression compared to healthy cells. Together, these results indicate that chronic alcohol exposure detrimentally alters the conducting airway epithelial cell barrier potentially through the loss of JAM‐A. Future directions include determining if other tight junction proteins are altered by alcohol and whether the alcohol‐induced reduction in JAM‐A is sufficient to cause barrier dysfunction in airway cells.