As COVID-19 cases sweep past the 70,000 mark in India, more information is being revealed regarding the nature of the disease. Recent research has documented the reason behind the disease more commonly affecting men.
According to a study published in the European Heart Journal, men have higher levels of angiotensin-converting enzyme 2 (ACE2) in their blood than women. The coronavirus uses its crown-like spike protein — from which the virus gained its name (corona is Latin for crown) — to bind to ACE2 on the surface of human cells in the bloodstream. From here, the viral cells are able to penetrate into the air sacs of the lungs, causing respiratory infection.
Being male is a significant risk factor for severe illness and death from the coronavirus disease (Covid-19) regardless of age, according to the study. Other factors that can contribute to higher risks of more severe effects include many underlying noncommunicable diseases and conditions such as diabetes, heart disease, or obesity.
ACE2 is not found exclusively in the lungs, but also in the heart, kidneys and tissues lining blood vessels. There are particularly high levels in the testes — likely explaining the higher concentration in the bloodstream in men.
“ACE2 is a receptor on the surface of cells,” said Dr Adriaan Voors, professor of cardiology at the University Medical Center Groningen in the Netherlands. “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, 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 presence of the enzyme within the heart as well as the lungs could also explain the particular correlation between coronavirus comorbidity with heart disease and death. The presence of the virus within heart tissue could exacerbate pre-existing conditions to the point where severe symptoms arise.
“The early explosion of underlying comorbidities such as heart disease, uncontrolled diabetes and lung problems in Indians raises their risk of severe disease and death at younger ages as compared to other countries,” commented Dr G. Khilnani, chairman of PSRI Institute of Pulmonary and Critical Care, and a member of the Delhi state government’s COVID-19 response committee. “That’s why continuing prescription medication for existing conditions is as important as washing hands and wearing masks.”