Mucin glycoproteins and airway secretions (MUC)

Mucin glycoproteins are high-molecular-weight, heavily glycosylated proteins that serve as the primary structural components of airway mucus. In the human respiratory tract, the gel-forming mucins MUC5AC and MUC5B are the most critical for forming the viscoelastic gel that traps inhaled particulates and pathogens for removal via mucociliary clearance (Fahy and Dickey, NEJM, 2010). Airway secretions also contain water, electrolytes, and defensive proteins, but in disease states, they can become pathologically thickened by the accumulation of extracellular DNA and filamentous actin from degraded neutrophils. This hyperviscosity leads to airway obstruction and recurrent infections in conditions like cystic fibrosis and COPD. Therapeutic strategies target these secretions by breaking down the mucin disulfide bonds, degrading DNA polymers, or hydrating the airway surface to facilitate clearance and improve pulmonary function (StatPearls, Mucolytic Agents, 2023).

Other names

Airway mucusTracheobronchial secretionsMUC5ACMUC5BRespiratory mucusBronchial secretions

Reduction of disulfide bridges in mucin polymers, enzymatic hydrolysis of extracellular DNA, osmotic hydration of the airway surface liquid, and stimulation of respiratory tract fluid secretion.