Introduction: COVID-19 is responsible for a global pandemic that is complicated by acute lung injury, and death The virus SARS-CoV-2 requires the ACE2 receptor and serine proteases to enter airway epithelial cells We sought to determine what factors were associated with levels of ACE2 expression and how this related to people with asthma and chronic obstructive pulmonary disease (COPD)

Methods: We obtained airway epithelial cells from 146 people, aged 2 to 89 from Perth and Newcastle The Newcastle cohort were enriched with people with asthma and COPD Gene expression for ACE2 and other genes potentially associated with SARS-CoV-2 cell entry were assessed by quantitative PCR and immunohistochemistry

Results: Increased gene expression for ACE2 from lower airway epithelial cells was associated with older age (p=0 02) and male sex (p=0 03), but not packet years smoked When we compared gene expression between adults with asthma, COPD and healthy controls, mean ACE2 was lower in asthma p=0 01 (Figure) Gene expression for Furin a protease that facilitates viral endocytosis was also lower in asthma (p=0 02), while ADAM-17, a disintegrin that has been shown to cleave ACE2 from the surface was increased p=0 02 We confirmed that ACE2 protein expression was lower in endobronchial biopsies from people with asthma

Conclusions: Increased ACE2 expression is seen in older people and males While people with asthma appear to have reduced expression Altered ACE2 expression in the lower airway may be an important factor in virus tropism to the lower airway