Increased expression of ACE2, the SARS-CoV-2 entry receptor, in alveolar and bronchial epithelium of smokers and COPD subjects

Jacobs, Merel; Van Eeckhoutte, Hannelore P.; Wijnant, Sara R. A.; Janssens, Wim; Joos, Guy F.; Brusselle, Guy G.; Bracke, Ken R.

Coronavirus Disease 19 (COVID-19) is a novel emerging respiratory disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and is causing a vast pandemic with huge medical, social, personal and financial impact. Angiotensin-converting enzyme 2 (ACE2) was identified as the cell entry receptor used by SARS-CoV-2 [1, 2]. Importantly, smokers and patients with COPD are at increased risk for severe complications and a higher mortality upon SARS-CoV-2 infection [3]. We hypothesised that ACE2 expression is increased in lungs of smokers and patients with COPD, which may at least partially explain their higher risk for a more severe course of COVID-19. Therefore, we aimed to investigate the expression of ACE2 on both mRNA and protein level in a large number of lung tissue specimens of well phenotyped subjects, including never smokers, current smokers without airflow limitation, and patients with COPD.