MUC5AC and chronic obstructive pulmonary disease: Moreover, ALI differentiated airway epithelial cultures recapitulate key aspects of epithelial host defense including coordinated ciliary beating, regulation of airway surface fluid height, CFTR-dependent Cl- and HCO3- efflux, production of the gel-forming mucins MUC5B and MUC5AC, and IgA pIgR in the context of COPD, making this model a gold standard for assessing cellular and microbiological responses to infection with and without anti-infective treatments (Gohy et al., 2014; Walker et al., 2017; Rayner et al., 2019; Zemke et.