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

Abstract

Angiotensin-converting enzyme 2 (ACE2) has been identified as the cell entry receptor used by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [1, 2]. Importantly, smokers and patients with COPD are at an increased risk of 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 of a more severe course of coronavirus disease 2019 (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. In this cross-sectional observational study, we analysed lung tissue specimens from 134 subjects from our large lung tissue biobank at Ghent University Hospital (Ghent, Belgium) and from explant lungs from end-stage COPD patients collected at UZ Gasthuisberg Leuven (Leuven, Belgium). Ex-smoking was defined as smoking cessation for ⩾1 year. COPD severity was defined according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification. Written informed consent was obtained from all subjects, and the study was approved by the medical ethical committees of Ghent University Hospital (2016/0132; 2019/0537) and the University Hospital Gasthuisberg Leuven (S51577). RNA extraction from lung tissue blocks of 120 subjects was performed with the miRNeasy Mini kit (Qiagen, Hilden, Germany). Next, cDNA was prepared with the EvoScript Universal cDNA Master Kit (Roche, Basel, Switzerland), followed by reverse transcriptase (RT)-qPCR analysis for ACE2 and 3 reference genes, as described previously [4, 5]. Sections from formalin-fixed paraffin-embedded lung tissue blocks of 87 subjects were stained for ACE2. After antigen retrieval with citrate buffer (Scytek, West Logan, UT, USA), the slides were incubated with anti-ACE2 antibody (polyclonal rabbit-anti-human, Abcam ab15248). Next, slides were coloured with diaminobenzidine (Dako, Carpinteria, CA, USA) and counterstained with Mayer's haematoxylin (Sigma-Aldrich, St Louis, MO, USA). Quantitative measurements of the ACE2-positive signal in alveolar tissue and bronchial epithelium were performed on images of stained paraffin sections as described previously [6]. Statistical analysis was performed using Sigma Stat software (SPSS 26.0, Chicago, IL, USA) and R3.5.1, using Kruskal-Wallis tests (on all six groups) followed by Mann-Whitney U-tests (for the comparison between two groups), and multivariable linear regression analyses. Using RT-PCR, ACE2 mRNA levels were determined in lung tissue from 120 subjects. ACE2 mRNA expression was significantly higher in the lung tissue of current smokers without airflow limitation and current smokers with COPD (GOLD stages II and III-IV) compared with never-smokers (figure 1a). In addition, ex-smokers without airflow limitation showed significantly lower ACE2 mR...

Tobacco and COVID-19: Understanding the science and policy implications

“…The results showed a dose-response relationship with smoking status such that ACE-2 expression was higher in current than former smokers than never smokers with the ACE-2 levels found to be related to the degree of pulmonary function impairment with a greater deficit showing higher ACE-2 levels. These findings are corroborated by those of other publications, including a meta-analysis from Cai et al 6 showing similar findings 7 , 8 . Notably, although further work is needed to define the role of nicotine or indeed upregulation of ACE-2 9 , it is possible that ACE-2 upregulation may explain the increased risk of severe COVID-19 in these populations, highlighting the importance of smoking cessation for these individuals and increased surveillance of these risk subgroups for prevention and rapid diagnosis of this potentially deadly disease.…”

Paradoxical effects of cigarette smoke and COPD on SARS-CoV2 infection and disease

“…ACE2 expression is highest in the conducting airways, waning in the more distal bronchiolar and alveolar lung regions 3 . There have been mixed reports on the effect of CS and COPD on SARS-CoV-2 infection 4 , with most studies showing an up-regulation of ACE2 in clinical and experimental models of smoke-induced lung disease [5][6][7][8][9][10] . In this study, we evaluated: 1) ACE2 and TMPRSS2 expression in the airways of smokers with COPD, compared to smoker and never smoker (NS) controls, and 2) ACE2 expression in lungs of mice acutely and chronically exposed to CS; and 3) the effect of CS on SARS-CoV2 infection of bronchial epithelial cells in vitro.…”

Clinical Features and Efficacy of Antiviral Drug, Arbidol in 220 Nonemergency COVID‐19 Patients from East-West-Lake Shelter Hospital in Wuhan: A Retrospective Case Series

“…Herein, we discovered the e cacy of Arbidol on viral shedding, thus accelerating disease relief in the nonemergency COVID-19 patients. We noticed that males displayed higher fever and more COVID-19 symptoms, which might due to the up-regulated SARS-Cov-2 receptor, angiotensin-converting enzyme 2 (ACE2) by smoking and testosterone level, as well as excessive immune-in ammatory response [10,11]. Furthermore, males exhibited better drug reactions, suggesting certain microenvironment (such as pH, ion, hormone and cytokines) might strengthen the e cacy of Arbidol.…”