Barrier function of airway tract epithelium

Ganesan, Shyamala; Comstock, Adam T; Sajjan, Uma S

Serous cells are found at the distal ends of submucosal glands and resemble goblet cells morphologically, but their granule content is more electron-dense. 16 Serous cells secrete the bulk of glandular fluid in response to secretogogues that use cAMP and/or Ca 2+ as second messengers. 17 The fluid secreted by these cells directly contributes to airway surface liquid (see later) volume, hydration of mucus released from goblet cells, 18, 19 and innate immunity. 20 Basal cells are connected to the basement membrane via hemodesmosomes, providing the foundation for the attachment of ciliated and goblet cells to basal lamina, and also have the potential to regulate inflammatory responses, oxidant defense and transepithelial water movement. 21 The most important feature of basal cells is their capacity to repopulate all the major cell types of conductive airway epithelium. [22] [23] [24] Basal cells are therefore thought to be the progenitor cells or the transient amplifying cells of the airway epithelium, 25 but this is yet to be confirmed.