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The New England Journal of Medicine published an article by Richard Boucher, MD, that redefines four lung diseases into a broad grouping called ‘Muco-Obstructive Lung Diseases.’

May 15, 2019

Richard Boucher, MD, the James C. Moeser Eminent Distinguished Professor of Medicine and director of the Marsico Lung Institute, wrote a peer-reviewed New England Journal of Medicine Review Article that redefines bronchiectasis, cystic fibrosis, primary ciliary dyskinesia, and chronic obstructive pulmonary disease into a broad grouping called ‘Muco-Obstructive Lung Diseases.’

The article is available to subscribers online and in the May 16, 2019 issue of the NEJM. What follows is a brief excerpt.

“A spectrum of lung diseases that affect the airways, including chronic obstructive pulmonary disease (COPD), cystic fibrosis, primary ciliary dyskinesia, and non–cystic fibrosis bronchiectasis, can be characterized as muco-obstructive diseases. These diseases have the clinical features of cough, sputum production, and episodic exacerbations that are often associated with a diagnosis of chronic bronchitis. However, neither “chronic bronchitis” nor

“hypersecretory diseases” adequately describes the diffuse mucus obstruction, airway-wall ectasia, chronic inflammation, and bacterial infection that are typical of these conditions; therefore, “muco-obstructive” may be a preferred descriptive term. Although asthma can also be associated with diffuse airway mucus obstruction, its distinct pathophysiological mechanisms preclude discussion in this grouping . . .

. . . Muco-obstructive diseases are characterized by mucus hyperconcentration. The four muco-obstructive diseases differ with respect to the epithelial abnormalities that produce mucus hyperconcentration but follow a final common path of mucus concentration–dependent formation of mucus plaques and plugs. Adherent mucus plaques may stimulate a positive-feedback muco-inflammatory cycle that renders mucus plaques permanent and damaging to airway walls. Therapies that are designed to rehydrate and restore mucous viscous or elastic properties are rational.

The challenge is to deliver these therapies to the small airways, where mucus obstruction may be complete and the physics of aerosol-deposition efficiency may be poor. However, the concept that these diseases may be highly treatable emanates from studies involving patients with cystic fibrosis in whom potentiators have reversed mucus obstruction in both large and small airways.”