Bronchial mucus

Bronchial mucus is a thin layer of airway surface liquid that coats the luminal surface of the bronchial airways, primarily composed of water, ions, mucin glycoproteins, and other macromolecules with protective functions. Its major role is to facilitate mucociliary clearance, trapping inhaled foreign particles, chemicals, and pathogens for expulsion via cilia beating and cough, while also providing antimicrobial, anti-protease, and anti-oxidant defenses.[1][2][5][6] The viscoelastic gel-like properties, imparted mainly by gel-forming mucins such as MUC5AC and MUC5B secreted by goblet cells and submucosal glands, enable effective particle entrapment and transport.[2][4][6] In healthy airways, mucus maintains a low viscosity periciliary layer for cilia function and a gel layer for trapping; dysregulation leads to hypersecretion or thickened mucus, impairing clearance.[1][4][9] Excessive bronchial mucus contributes to pathology in diseases like cystic fibrosis, COPD, and asthma, where altered mucin production and composition cause airway obstruction, inflammation, and recurrent infections.[4][5][6] Membrane-tethered mucins like MUC1 and MUC4 further protect epithelial surfaces and modulate signaling.[6] Although not a molecular target like a receptor or enzyme, bronchial mucus properties are indirectly modulated by therapies addressing mucin hypersecretion or clearance, such as hydration or mucolytics.[5][11]

Other names

Airway mucuslung mucusphlegmsputum