Fig. 1.

ACE2 expression in bronchial and alveolar epithelium from COPD patients, smoker and never-smoker (NS) controls. The number of ACE2+ cells in the central airway bronchial epithelium was similar between patients with chronic obstructive pulmonary disease (COPD), smokers without COPD and NS controls. In A, representative IHC for ACE2 images of central airways of a COPD patient (upper panel) and a smoker without COPD. The insets show details of the ciliated bronchial epithelium. The number of ACE2+ cells in the alveolar epithelium (B) and peripheral airway epithelium (C), normalized for length of the alveolar wall or basement membrane, respectively, was lower in patients with COPD versus smokers without COPD and NS controls. In D, triple immunofluorescence representative images of alveolar (upper panels) and bronchiolar epithelium (lower panels) from a COPD patient, a smoker without COPD, and a never-smoker (NS) where ACE2 staining is identified by green fluorochrome, the epithelium is identified by red fluorochrome, and the color yellow is obtained by merging the two fluorochromes. In E, the levels of ACE2 mRNA from peripheral lung samples were decreased between patients with chronic obstructive pulmonary disease (COPD) versus both smoker without COPD and NS controls. The red circles indicate the current smokers among the smoker controls and COPD patients