MUC5AC and chronic obstructive pulmonary disease: Dysregulation of secretory proteins (e.g., MUC5B, MUC5AC, and CC10) and dysfunction of ciliated cells can promote mucus accumulation in the airways, compromising the immune response and perpetuating tissue damage, leading to disease exacerbations (e.g., nasal polyp, asthma, and chronic obstructive pulmonary disease) (Thomas et al., 2010; De Rose et al., 2018; Peng et al., 2019).