Eosinophils, mucus plugs, and clinical outcomes: Findings from two COPD cohorts

Type 2 inflammation (Th2i) —indicated by blood eosinophil counts— and airway-occluding mucus plugs (MPs) on computed tomography (CT) are frequent phenotypes in people with COPD. [1–4] Furthermore, the Th2i pathway involves type 2 helper T cells and epithelial-derived cytokines, such as interleukin (IL-) 33 and thymic stromal lymphopoietin (TSLP), that drive a cascade of events, including eosinophils mobilization and activation in the airways. [5] A persistent Th2i milieu leads to airway structural changes, such as mucus gland hypertrophy, ensuing mucus hypersecretion, and plug formation. [5, 6] Therefore, we tested the hypothesis that high blood eosinophils are associated with airway MPs. We also sought to determine the association of those phenotypes with functional and clinical measures of COPD.