A recently published study shows that men’s blood contains greater concentrations of an enzyme that helps SARS-CoV-2 infect cells.
Researchers in the Netherlands have discovered that men have higher levels of ACE2 in their blood than women. The enzyme, found in higher concentrations in male blood plasma, allows the virus to infect cells with the enzyme.
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.
High levels of ACE2 are present in the lungs and it is thought to play a crucial role in the progression of lung disorders related to COVID-19.
The researchers measured ACE2 concentrations in blood samples taken from two groups of heart failure patients from 11 European countries. Two groups of men and two groups of women were tested with median ages ranging from 69 to 76.
ACE2 is found in the lungs, heart, kidneys and the tissues lining blood vessels. There are particularly high levels in the testes. The researchers speculate that its regulation in the testes might partially explain higher ACE2 concentrations in men, and why men are more vulnerable to COVID-19.
However, the researchers only measured concentrations of ACE2 in plasma, not in tissues. It is the ACE2 in the lung tissues that are thought to be important for viral infection of the lungs, not ACE2 concentrations in the blood. And the study looked only at an older age group with heart failure who were not infected with SARS-CoV-2.
Despite these limitations, the findings might still prove to be another important piece of the puzzle to understand how the disease affects some more than others.
Research paper (in English)