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Alcohol Decreases the Barrier Function of Airway Epithelial cells through the TGFß1 Pathway
Author(s) -
Easley Kristen,
Mehta Ashish,
Staitieh Bashar,
Koval Michael
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.04842
Subject(s) - barrier function , tight junction , in vitro , ards , lung , epithelium , microbiology and biotechnology , immune system , immunology , occludin , medicine , chemistry , biology , pathology , biochemistry
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 are the first line of defense against infectious pathogens in the lung. We hypothesize that alcohol exposure causes a decrease in barrier function of airway epithelial cells through a TGFß1‐dependent mechanism. To test this, we cultured primary airway epithelial cells isolated from rats and humans on Transwell permeable supports and differentiated them in vitro at air liquid interface (ALI). We treated cells in vitro with 60mM or 100mM ethanol changed daily for 2 weeks and measured barrier function by transepithelial electrical resistance (TER). We found that ethanol caused a decrease in barrier function compared to control cells. However, cells treated with ethanol and a TGFß1 inhibitor had barrier function similar to control cells. 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. Rat airway cells exposed to ethanol in vitro also show a decrease in JAM‐A at both the RNA and protein level. 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.