Airway gland structure and function

Jonathan Widdicombe, Jeffrey J. Wine

Research output: Contribution to journalArticle

73 Scopus citations

Abstract

Submucosal glands contribute to airway surface liquid (ASL), a film that protects all airway surfaces. Glandular mucus comprises electrolytes, water, the gel-forming mucin MUC5B, and hundreds of different proteins with diverse protective functions. Gland volume per unit area of mucosal surface correlates positively with impaction rate of inhaled particles. In human main bronchi, the volume of the glands is ∼50 times that of surface goblet cells, but the glands diminish in size and frequency distally. ASL and its trapped particles are removed from the airways by mucociliary transport. Airway glands have a tubuloacinar structure, with a single terminal duct, a nonciliated collecting duct, then branching secretory tubules lined with mucous cells and ending in serous acini. They allow for a massive increase in numbers of mucus-producing cells without replacing surface ciliated cells. Active secretion of Cl<sup>−</sup> and HCO<inf>3</inf><sup>−</sup> by serous cells produces most of the fluid of gland secretions. Glands are densely innervated by tonically active, mutually excitatory airway intrinsic neurons. Most gland mucus is secreted constitutively in vivo, with large, transient increases produced by emergency reflex drive from the vagus. Elevations of [cAMP]<inf>i</inf> and [Ca<sup>2+</sup>]i coordinate electrolyte and macromolecular secretion and probably occur together for baseline activity in vivo, with cholinergic elevation of [Ca<sup>2+</sup>]<inf>i</inf> being mainly responsive for transient increases in secretion. Altered submucosal gland function contributes to the pathology of all obstructive diseases, but is an early stage of pathogenesis only in cystic fibrosis.

Original languageEnglish (US)
Pages (from-to)1241-1319
Number of pages79
JournalPhysiological Reviews
Volume95
Issue number4
DOIs
StatePublished - Sep 2 2015

ASJC Scopus subject areas

  • Physiology
  • Molecular Biology
  • Physiology (medical)

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