Massachusetts: Evidence from a large study of several thousand patients shows that men have higher concentrations of angiotensin-converting enzyme 2 (ACE2) in their blood than women. Since ACE2 enables the coronavirus to infect healthy cells, this may help to explain why men are more vulnerable to COVID-19 than women.
The study, published in the European Heart Journal also found that heart failure patients taking drugs targeting the renin-angiotensin-aldosterone system (RAAS), such as angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs), did not have higher concentrations of ACE2 in their blood.
Dr Adriaan Voors (MD-PhD), Professor of Cardiology at the University Medical Center Groningen (The Netherlands), who led the study, said: “Our findings do not support the discontinuation of these drugs in COVID-19 patients as has been suggested by earlier reports.” Some recent research suggested that RAAS inhibitors might increase concentrations of ACE2 in plasma - the liquid part of blood - thereby increasing the risk of COVID-19 for cardiovascular patients taking these drugs.
The current study indicates that this is not the case, although it looked only at ACE2 concentrations in plasma, not in tissues such as lung tissue. In addition, the study cannot provide definitive evidence on the effects of RAAS inhibitors in patients with COVID-19.
Its conclusions are mainly restricted to heart failure patients, and the patients did not have COVID-19, so the researchers cannot provide a direct link between the course of the disease and ACE2 plasma concentrations.
“ACE2 is a receptor on the surface of cells. It binds to the coronavirus and allows it to enter and infect healthy cells after it is has been modified by another protein on the surface of the cell, called TMPRSS2,” said Prof Voors.
“High levels of ACE2 are present in the lungs and, therefore, it is thought to play a crucial role in the progression of lung disorders related to COVID-19,” Voors added.
When the researchers looked at a number of clinical factors that could play a role in ACE2 concentrations, including the use of ACE inhibitors, ARBs and mineralocorticoid receptor antagonists (MRAs), as well as a history of chronic obstructive pulmonary disease, coronary artery by-pass graft and atrial fibrillation, they found that male sex was the strongest predictor of elevated ACE2 concentrations.