PIGR and chronic obstructive pulmonary disease: The pIgR/SC system is defective in the COPD AE, both in situ and in vitro in COPD-derived ALI-reconstituted AE (Carlier et al., 2021; Gohy et al., 2014), and local S-IgA deficiency in small airways was associated with epithelial inflammation and remodeling (Polosukhin et al., 2011, 2017).