New information on the cellular receptor for SARS-CoV-2
Two recent publications have reported important new data on ACE2, the cellular receptor protein for the SARS-CoV-2 virus. Although these studies were not carried out on COVID-19 patients, their findings may be highly relevant for our understanding and treatment of the disease. Both of these studies used the Olink ACE2 assay in our Olink CARDIOVASCULAR II panel.
Sama et. al. in the European Heart Journal looked at circulating levels of ACE2 in heart failure patients, and the effects of treatment with renin–angiotensin–aldosterone system (RAAS) inhibitors. There have been suggestions that patients treated with RAAS inhibitors have a higher incidence of COVID-19, possibly because these drugs increase plasma levels of ACE2. In this thorough study, they found no evidence that RAAS inhibitors affect plasma ACE2 levels, arguing against the idea that these drugs might increase the vulnerabilty to COVID-19. They also found higher levels of ACE2 in men compared to women, which may be significant given that more men than women test postive for SARS-CoV-2 (58% vs 42%).
Swärd et. al. in Critical Care report a population study looking for differences in circulating levels of ACE2 that may be linked to the age and sex of the subject. In this longitudinal study that followed individuals from the mean ages of 9.9 to 23.5 years, they showed a significant increase in circulating ACE2 with increasing age, and that levels in male subjects were significantly higher than in females at all of the time points measured (in agreement with the findings from Sama et. al. above). These differences mirror the broad risk categories for COVID-19: adults > children and men > women, and the authors suggest that further research is needed to establish whether ACE2 levels can be considered as a risk factor for COVID-19