気道分泌亢進の病態と治療

Excessive sputum due to airway hypersecretion is one of the common symptoms in respiratory diseases such as asthma and bronchiectasis. Airway secretion is mainly composed of mucin from airway goblet cells and submucosal glands and water through ion transport in airway epithelial cells. Although airway secretion plays an important role in defense mechanism, the increase in intraluminal mucus may lead to the impairment of mucociliary clearance and airway obstruction. Airway secretion is stimulated by autonomic nervous system and a variety of chemical mediators, but these mechanisms are different under individual conditions. It is thus important to select mucoregulating drugs after understanding the pathophysiology of hypersecretion. Recent evidence suggests that goblet cell hyperplasia and mucin overproduction are associated with Th2 cytokines such as IL-13, EGF-receptor, and Ca activated Cl channels. The new therapeutic approach based on the evidence could be developed in the future.