ACE2 and chronic obstructive pulmonary disease: Similarly, in Cohort 2 we found both alveolar (mainly type II cells, ATII, Fig. 1B, D) and bronchiolar (mainly club cells and goblet cells, Fig. 1C, D) ACE2 protein expression levels, and ACE2 mRNA pulmonary levels (Fig. 1E) to be lower in COPD patients versus both smokers without COPD and NS controls.