SARS-CoV-2 (COVID-19) Adhesion Site Protein Upregulation in Small Airways, Type 2 Pneumocytes, and Alveolar Macrophages of Smokers and COPD – Possible Implications for Interstitial Fibrosis

Abstract

Samuel James Brake,1 Mathew Suji Eapen,1 Kielan Darcy McAlinden,1 James Markos,1,2 Greg Haug,1,2 Josie Larby,1,2 Collin Chia,1,2 Ashutosh Hardikar,1,3 Gurpreet Kaur Singhera,4,5 Tillie L Hackett,4,5 Wenying Lu,1 Sukhwinder Singh Sohal1 1Respiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Launceston, TAS, 7248, Australia; 2Department of Respiratory Medicine, Launceston General Hospital, Launceston, TAS, 7250, Australia; 3Department of Cardiothoracic Surgery, Royal Hobart Hospital, Hobart, TAS, 7000, Australia; 4Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, BC, Canada; 5Department of Medicine, University of British Columbia Centre for Heart Lung Innovation, St. Paul’s Hospital, Vancouver, BC, CanadaCorrespondence: Sukhwinder Singh SohalRespiratory Translational Research Group, Department of Laboratory Medicine, School of Health Sciences, College of Health and Medicine, University of Tasmania, Locked Bag – 1322, Newnham Drive, Launceston, TAS, 7248, AustraliaTel [phone]Email [email protected]: Smokers and patients with COPD are highly susceptible to SARS-CoV-2 infection, leading to severe COVID-19.Methods: This cross-sectional study involved resected lung tissues from 16 patients with GOLD stage I or II COPD; of which 8 were current smokers COPD (COPD-CS), and 8 ex-smokers COPD (COPD-ES), 7 normal lung function smokers (NLFS), 9 patients with small airways disease (SAD), and 10 were never-smoking normal controls (NC). Immunostaining for ACE2, Furin, and TMPRSS2 was performed and analysed for percent expression in small airway epithelium (SAE) and counts for positively and negatively stained type 2 pneumocytes and alveolar macrophages (AMs) were done using Image ProPlus V7.0. Furthermore, primary small airway epithelial cells (pSAEC) were analysed by immunofluorescence after exposure to cigarette smoke extract (CSE).Results: ACE2, Furin, and TMPRSS2 expression significantly increased in SAE and type 2 pneumocytes in all the subjects (except Furin for NLFS) compared to NC (p < 0.001). Similar significance was observed for ACE2 positive AM (p < 0.002), except COPD-ES, which decreased in ACE2 positive AMs (p < 0.003). Total type 2 pneumocytes and AMs significantly increased in the pathological groups compared to NC (p < 0.01), except SAD (p = 0.08). However, AMs are significantly reduced in COPD-ES (p < 0.003). Significant changes were observed for tissue co-expression of Furin and TMPRSS2 with ACE2 in SAE, type 2 pneumocytes and AMs. These markers also negatively correlated with lung function parameters, such as FEV1/FVC % predicted, FEF25-75%, DLCO% predicted. A strong co-localisation and expression for ACE2 (p < 0.0001), Furin (p < 0.01), and TMPRSS2 (p < 0.0001) was observed in pSAEC treated with 1% CSE than controls.Discussion: The increased expression of ACE2, TMPRSS2 and Furin, in the SAE, type 2 pneumocytes and AMs of smokers and COPD are detrimental to lung function and proves that these patient groups could be more susceptible to severe COVID-19 infection. Increased type 2 pneumocytes suggest that these patients are vulnerable to developing post-COVID-19 interstitial pulmonary fibrosis or fibrosis in general. There could be a silently developing interstitial pathology in smokers and patients with COPD. This is the first comprehensive study to report such changes.Keywords: COVID-19, SARS-CoV-2, smoking, COPD, ACE2, type 2 pneumocytes, alveolar macrophages, epithelium

Keywords

• covid-19
• sars-cov-2
• smoking
• copd
• ace2
• type ii pneumocytes
• alveolar macrophages
• epithelium.