In a new study, researchers found 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.
They 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 levels of ACE2 in their blood.
The findings do not support the discontinuation of these drugs in COVID-19 patients as has been suggested by earlier reports
The research was conducted by a team at the University Medical Center Groningen.
Recent research has 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 shows 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.
The team says 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.
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.
The team is already studying differences in markers of disease in the blood between men and women before the coronavirus outbreak. The results became available soon after the pandemic began.
The researchers measured ACE2 concentrations in blood samples taken from two groups of heart failure patients from 11 European countries.
There were 1485 men and 537 women in the first group. Then the researchers validated their findings in the second group of 1123 men and 575 women.
They found that one of the strongest biomarkers, ACE2, was much higher in men than in women, and they realized that this had the potential to explain why men were more likely to die from COVID-19 than women.
The team says they found no evidence that ACE inhibitors and ARBs were linked to increased ACE2 concentrations in blood.
The findings do not suggest that MRAs should be discontinued in heart failure patients who develop COVID-19.
They are a very effective treatment for heart failure and the effects on viral infection should be weighed carefully against their proven benefits.
The lead author of the study is Dr. Adriaan Voors (MD-Ph.D.), Professor of Cardiology.
The study is published in the European Heart Journal.
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