Why are men more susceptible to Covid-19? An enzyme could be to blame

A large study involving several thousands of patients may reveal why men seem more vulnerable to Covid-19 than women.

The study was published in the European Heart Journal on 10 May 2020 and was featured in a news release. It essentially revealed that men have higher concentrations of an enzyme called ACE2 in their blood.

What is the role of ACE2?

In a previous Health24 article, we explained why SARS-Cov-2 is so contagious. It boils down to the proteins in the spikes of the virus that gives it its name – coronavirus – which is derived from the Latin “corona”, meaning crown.

These proteins in the spikes successfully bind to a receptor on human cells, called the angiotensin-converting enzyme 2 (ACE2). Once the virus binds to cells, it starts to multiply inside the host, which ultimately makes us sick.

And because men have a higher concentration of this enzyme, it is no surprise that they are far more likely to bear the brunt of Covid-19 than women.

The link between heart failure patients and ACE2

Several previous studies suggested that heart failure patients – who take drugs to target the renin-angiotensin-aldosterone system (RAAS), such as angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) – could have higher concentrations of ACE2 in blood plasma, thus increasing their risk of Covid-19. The current study, however, found that this is not the case. 

Patients taking these drugs should therefore not stop. Dr Adriaan Voors, Professor of Cardiology at the University Medical Center Groningen (The Netherlands) said in a statement that the study findings indicate that these drugs should not be discontinued, as other recent research might have suggested.

Dr Voors further stated in the news release: "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."

Limitations of study

While the study was quite large (1 485 men and 537 women in the first group and 1 123 men and 575 women in the second group), further research is needed.

"The effect of MRAs on ACE2 concentrations is not clear, as the weak increase in concentrations in the validation cohort was not seen in the index cohort. Our 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 hypothetical effects on viral infection should be weighed carefully against their proven benefits," Dr Voors said.

Image credit: Unsplash

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