Enzyme may shed light on vulnerability of men

“In many ways, men are more at risk, and this has been shown in previous epidemics.”

Dr. Mary Norine Walsh medical director for heart failure and cardiac transplantation at St. Vincent Heart Center in Indianapolis

An enzyme may help explain why anecdotal reports suggest men are more likely than women to suffer from the coronavirus and its severe complications, a new study shows.

The study, published in the peer-reviewed European Heart Journal, found that men have higher concentrations of the enzyme in their blood, which may make them more vulnerable to COVID-19 than women.

Researchers measured concentrations in blood samples taken from two groups of heart failure patients from 11 European countries. There were 2,608 men and 1,112 women ages 69 to 76 when combining both groups.

The enzyme in question is called angiotensin-converting enzyme 2 (ACE2). It’s natural to the human body and can be found in the lungs, heart, kidneys and tissues lining the blood vessels.

It also enables the coronavirus to infect healthy cells.

“ACE2 is a receptor on the surface cells. It binds to the coronavirus and allows it to enter and infect healthy cells after it has been modified by another protein on the surface of the cell,” said Dr. Adriaan Voors, professor of cardiology at the University Medical Center Groningen in the Netherlands.

Voors says high levels of ACE2 in the lungs is thought to play a crucial role in the progression of lung disorders related to COVID-19.

Dr. Mary Norine Walsh, medical director for heart failure and cardiac transplantation at St. Vincent Heart Center in Indianapolis, can confirm the enzyme is involved in the infection process.

But, she says, the report findings can’t be extrapolated to all men because the study population was restricted to heart failure patients. Researchers don’t know if the enzyme is higher in healthy or younger men.

Walsh also argued that other factors can account for why men are more vulnerable to COVID-19 than women. She said men also have higher rates in hypertension and, in many parts of the world, higher rates of smoking.

“In many ways, men are more at risk, and this has been shown in previous epidemics,” she said. “This isn’t the first time that we’ve seen this.”

Another limitation study authors mention is that researchers looked at ACE2 in plasma from blood samples, not from tissue. That is important because scientists believe ACE2 in the lung tissue is what’s important to the viral infection, not the plasma.

In any case, Walsh says, it’s vital to protect oneself from the virus.

“The take-home for anybody reading this is to always remain vigilant,” she said. “No matter who you are.”