The pathobiology and treatment of mucus plugs in asthma and COPD: state of the art

Recent studies using computed tomography have uncovered a high prevalence of airway mucus plugs in patients with asthma and COPD. These mucus plugs persist in the same airways for years and often occur in patients without symptoms of cough and sputum production. Mucus plugs associate strongly with measures of airflow obstruction and disease morbidity in both asthma and COPD, and they occur and persist despite treatment with high doses of inhaled and oral corticosteroids. Thus, airway mucus plugs have emerged as an underappreciated airway pathology in asthma and COPD and a cause of persistent airflow obstruction and disease morbidity that can be specifically targeted for treatment. This narrative review covers the pathobiology of mucus plugs in asthma and COPD with three areas of emphasis: 1) prevalence and clinical features; 2) mechanisms of formation and persistence; and 3) current and emerging treatments.