Alcohol and the alveolar epithelial barrier

Project Summary: The COVID-19 pandemic represents the most significant public health crisis to occur in generations. A majorcause of death due to COVID-19 is acute respiratory distress syndrome (ARDS). Whether chronic alcohol usedisorder exacerbates the severity of COVID-19 is not known, but is highly likely given the known impact ofalcohol on several organ systems including priming the lung epithelial barrier for increased paracellular leak. Inaddition, it is well established that chronic alcohol consumption exacerbates the severity of lung injury whencombined with an additional insult, a so-called "second hit". Of note, alcoholic lung syndrome increases theincidence of ARDS by 3-4 fold when compared with non-alcoholic ICU patients. We have identified propertiesof SARS-CoV-2 that predispose it towards a milder phase of infection, related to the virus E protein. Theoriginal SARS coronavirus, SARS-CoV-1, has an E protein that specifically targets tight junction protein PDZbinding motifs and thus readily disrupts the epithelial barrier of infected epithelia. By contrast, the COVID-19virus SARS-CoV-2 has E protein mutations that inhibit its ability to bind to PDZ binding motifs which can helppreserve infected epithelial cell barrier function. However, SARS-CoV-2 in the context of alcoholic lungsyndrome is more likely to result in a more severe outcome, since the epithelial barrier is already impaired as aresult of chronic alcohol abuse. Primary human bronchiolar epithelial cells derived from alcoholic and non-alcoholic subjects will be infected with SARS-CoV-2 in vitro and we will measure several outcome variablesrelated to severity of infection. We also have preliminary data showing that cells from alcoholics retainsignature differences in gene expression and function relative to non-alcoholic cells, leading to decreasedbarrier function and altered cell morphology. This supports a hypothesis that chronic alcohol exposure inducespersistent, epigenetic changes to the airway epithelial cell genome. In this supplement proposal, we willdetermine the impact of SARS-CoV-2 on the epigenome of host cells from alcoholics and non-alcoholics,focusing on DNA methylation. Of particular interest will be to examine the impact of DNA methylation inducedby alcohol and/or SARS-CoV-2 infection on the expression and downstream targets of the transcription factorsNrf2 and PU.1, known to be impaired by chronic alcohol exposure and that play key roles in regulatingepithelial antiviral responses. We will also identify novel host genome loci showing patterns of differentialmethylation that correlate with disease severity. We anticipate that identifying differentially methylated lociimpacted by chronic alcohol exposure and SARS-CoV-2 infection will lead to drug targets with the potential toreduce the severity of COVID-19 in alcoholic patients.