Inflammation and Treatment in Asthma and COPD

By James F. Donohue, MD, FCCP; and Jill A. Ohar, MD, FCCP

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COPD

Pathophysiology

COPD primarily affects the distal airways.¹¹ Generally, inflammation affects bronchioles at the level of the respiratory bronchiole extending to the alveolar wall.^11,12Airway walls are infiltrated with macrophages and lymphocytes. In contrast to asthma, the airway lymphocytes tend to be CD8+ rather than CD4+ cells. The CD4+ cells that are present in COPD tend to be Th₁ rather than the Th₂ cells found in asthma. Neutrophils are found in greater numbers in the airway lumen, and peribronchiolar fibrosis is seen in mid- to late-stage disease. Affected airways tend to be < 2 mm in diameter; airway obstruction results from structural narrowing caused by the inflammatory process, loss of elastic recoil due to breakdown of intra-alveolar elastic fibers, and loss of alveolar attachments from emphysema-induced alveolar septal destruction.¹¹ Neutrophils are increased in and around bronchial glands, where the elastase they produce promotes mucus hypersecretion. Although neutrophils, macrophages, and lymphocytes predominate in stable COPD, eosinophils may be increased in the airway walls and lumens in COPD exacerbations.

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