Airway epithelial cells and respiratory tract mucus

The airway epithelial cells and the respiratory tract mucus layer form the integrated "mucociliary escalator," which serves as the primary physical and immunological defense against inhaled pathogens and particulates [1]. The epithelium is a pseudostratified layer containing ciliated cells, which provide the motive force for clearance, and goblet cells, which secrete the gel-forming mucins MUC5AC and MUC5B [2]. These mucins create a viscoelastic hydrogel that traps debris, while the underlying airway surface liquid (ASL) provides the necessary environment for ciliary activity [3]. In chronic respiratory diseases such as cystic fibrosis and COPD, mucus becomes hyperviscous or overproduced, leading to airway obstruction, inflammation, and a niche for bacterial growth [1,4]. Therapeutic strategies targeting this system include mucolytics that break down the mucus structure and ion channel modulators that aim to rehydrate the ASL to restore effective clearance [1,2]. References: [1] Fahy JV, Dickey BF. N Engl J Med. 2010;363(23):2233-47. [2] Whitsett JA. Ann Am Thorac Soc. 2018;15(Suppl 3):S143-S148. [3] Bustamante-Marin XM, Ostrowski LE. Cold Spring Harb Perspect Biol. 2017;9(4):a028241. [4] Rogers DF. Respir Care. 2007;52(9):1134-46.

Other names

Respiratory epitheliumAirway surface liquidTracheobronchial mucusBronchial epitheliumMucociliary escalator

Reduction of disulfide bonds in mucin polymers (mucolysis); enzymatic cleavage of extracellular DNA; modulation of CFTR-mediated chloride transport to increase hydration; suppression of inflammatory cytokine production in epithelial cells.