Plugging (publicising) to prevent mucous plugging

Abstract

Mucus has long been known to exist in airways, but it is only relatively recently that mucous hypersecretion has been widely recognised to play major roles in the pathogenesis of chronic obstructive lung diseases, including asthma, chronic obstructive pulmonary disease and cystic fibrosis. Airway mucus is a complex mixture of liquids and proteins. Important components are gel-forming mucins, which are high-molecular-weight glycoproteins whose unusual viscoelastic properties permit the gel to interact with epithelial cilia, thus promoting clearance of deposited foreign materials. Airway mucins are reviewed in detail elsewhere 1. Owing to its clinical importance and the limited effectiveness of current therapies 2, 3, mucous hypersecretion is an appealing target for novel therapies. How has mucus evolved as an important source of host defence in the airways, and what are the roles of mucous secretion in chronic obstructive airway diseases? When fish migrated from water to land, lungs replaced gills for respiratory gas exchange. Placement of the lungs adjacent to the heart, deep within the thoracic cavity, added the requirement of an air tube to transport inspired air to the lungs. However, inspired air also contains microbes and other irritants, which are deposited on the airway epithelial surface, causing inflammation and invading the host. In response, the host has developed defensive actions, which normally destroy and clear the invading organisms. Among the defensive host responses to inhaled invaders, secreted airway mucins normally play major protective roles. The recruited mucins entrap the invaders, which are then cleared by cough and mucociliary clearance 4. In healthy individuals, mucins in the airways are sparse but sufficient to accomplish entrapment and clearance of invaders efficiently and with minimal symptoms. However, in chronic inflammatory airway diseases, such as asthma, exaggerated mucin production occurs, leading to symptoms and airway obstruction. In the major …