Epithelial-Mesenchymal-transition (EMT) and epithelial integrity: role of viral/ bacterial infections in an “in vitro” COPD modelling

COPD is susceptible to viral and bacterial infections. The airway epithelium plays a pivotal role as physical/functional barrier injured by allergens, microbes, tobacco smoke. We investigated the effects of cigarette smoke extract (CSE), lipopolysaccharide (LPS), poly(I:C) and the potential protective role of Resveratrol (RSV) on EMT, and epithelial integrity. Zonula occludens-1 (ZO-1), claudin, E-cadherin and vimentin were evaluated using RT-qPCR in A549 cells long-term cultured in an Air-liquid Interface (ALI) system and stimulatedwith CSE (5%), LPS (1µg/ml), poly(I:C) (50 µg/ml) alone or in combination. Furthermore, we investigated the effects of RSV afterwards CSE stimulation on E-cadherin, claudin and vimentin using western blotting. Instead, cell proliferation was evaluated using the MTS assay. LPS and poly(I:C) alone highlight a decrease of ZO-1, E-cadherin and claudin levels. In contrast, CSE treatment alone or in combination with LPS and poly(I:C) induced higher levels of ZO-1, E-cadherin, claudin, and vimentin. Combined stimuli increased cell proliferation. Moreover, RSV inhibited the levels of E-cadherin and claudin after CSE treatment. The epithelial cells exposure to smoke might induce lung barrier dysfunction. Moreover, the stimuli combination might induce phenotypic switch of epithelial cells promoting EMT transition and remodeling. These evidences might influence the pathophysiology of COPD exacerbations. Lastly, RSV might suppress the disfunctions highlighting it a potential therapeutic candidate to support the improvement of the exacerbation of COPD reducing the risk of disease progression of toward lung cancer.