Inter-subject variation in ACE2 protein expression in human airway epithelia and its relationship to SARS-CoV-2 infection.

SARS-CoV-2 initiates entry into airway epithelia by binding its receptor, ACE2. To explore whether inter-individual variation in ACE2 abundance contributes to variability in COVID-19 outcomes, we measured ACE2 protein abundance in primary airway epithelial cultures derived from 58 human donor lungs. We found no evidence for sex- or age-dependent differences in ACE2 protein expression. Further, we found that variations in ACE2 abundance had minimal effects on viral replication and induction of the interferon response in airway epithelia infected with SARS-CoV-2. Our results highlight the relative importance of additional host factors, beyond viral receptor expression, in determining COVID-19 lung disease outcomes.