Claudin‐5 increases alveolar permeability in alcoholic lung syndrome by destabilizing claudin‐18/zonula occludens‐1 interactions (716.4)

Abstract

We found that alcohol abuse increases the severity of acute respiratory distress syndrome (ARDS) by impairing alveolar epithelial cell (AEC) tight junctions. In a rat model of chronic alcohol ingestion, decreased AEC barrier function was accompanied by increased claudin‐5 (cldn‐5) and claudin‐18 (cldn‐18) expression. Immunofluorescence of model type I AECs cultured on Transwell permeable supports showed that paracellular leak in cells from alcohol fed rats was accompanied by disrupted tight junction morphology. We then used Stochastic Optical Reconstruction Microscopy (STORM) which increases the resolution of immunofluorescence to 20 nm. STORM revealed that alcohol caused a significant decrease in co‐localization between AEC cldn‐18 and ZO‐1 along with increased co‐localization between cldn‐18 and cldn‐5. Thus, cldn‐5 binding to cldn‐18 inhibits binding to ZO‐1 which destabilizes tight junctions. We found that shRNA targeting to decrease cldn‐5 expression improved AEC tight junction morphology and function. Conversely, transfecting cells to increase expression of YFP‐tagged cldn‐5 altered tight junction morphology and impaired barrier function. Thus, increased cldn‐5 was necessary and sufficient to inhibit cldn‐18 assembly and function. These data suggest that targeting cldn‐5 may provide a therapeutic strategy to improve barrier function in ARDS.Grant Funding Source: Emory URC, NIH‐NIAAA, NIH‐NHLBI, DAAD