Clinical issues of mucus accumulation in COPD

Abstract

Airway mucus is part of the lung's native immune function that traps particulates and microorganisms, enabling their clearance from the lung by ciliary transport and cough. Mucus hypersecretion and chronic productive cough are the features of the chronic bronchitis and chronic obstructive pulmonary disease (COPD). Overproduction and hypersecretion by goblet cells and the decreased elimination of mucus are the primary mechanisms responsible for excessive mucus in chronic bronchitis. Mucus accumulation in COPD patients affects several important outcomes such as lung function, health-related quality of life, COPD exacerbations, hospitalizations, and mortality. Nonpharmacologic options for the treatment of mucus accumulation in COPD are smoking cessation and physical measures used to promote mucus clearance. Pharmacologic therapies include expectorants, mucolytics, methylxanthines, beta-adrenergic receptor agonists, anticholinergics, glucocorticoids, phosphodiesterase-4 inhibitors, antioxidants, and antibiotics.

Keywords: chronic bronchitis; chronic obstructive pulmonary disease; mucus; sputum.

Figure 1

Causes of excessive mucus in COPD. Notes: Reprinted with permission of the American Thoracic Society. Copyright © 2013 American Thoracic Society. Kim V, Criner GJ, 2013, Chronic bronchitis and chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 187(3):228–237. Official journal of the American Thoracic Society. Abbreviations: PEF, peak expiratory flow; COPD, chronic obstructive pulmonary disease.

Figure 2

MM and smooth muscle hypertrophy in a small airway from a COPD patient. Note: Hematoxylin and eosin stain. Abbreviations: MM, mucous metaplasia; SMH, smooth muscle hypertrophy; COPD, chronic pulmonary disease.

Figure 3

Goblet cell hyperplasia. Notes: Periodic acid Schiff–Alcian Blue stain. Higher magnification of a small airway quadrant is shown here. Goblet cells appear in an intense blue–purple color with periodic acid Schiff–Alcian Blue stain.