ADAM17 and chronic obstructive pulmonary disease: 2001). However, this is in contrast to the secretion of the innate immune mediators IL‐8 and ribonuclease 7, which were also detected at the apical surface (Amatngalim et al. 2015). A polarized ADAM17‐mediated secretion toward underlying tissue may be relevant for lung tissue remodeling through autocrine, paracrine, extracrine (exosomal targeted receptor activation) pathways in COPD (Booth et al. 2007; Zhou et al. 2012).