TJP1 and chronic obstructive pulmonary disease: Cigarette smoke-exposed COPD HBEC show decreased E-cadherin and ZO-1 expression and reduced transepithelial electric resistance (TEER) when compared with smokers without COPD (Milara et al, 2013; Heijink et al, 2014) and after 4 wk culture, the COPD ALI-AE displays altered lineage differentiation, decreased pIgR expression, and EMT (Gohy et al, 2014, 2015, 2019), along with increased cytokine release (Schneider et al, 2010).