Every week, the alarming truth about the Covid-19 coronavirus becomes clearer. Some of us will die from it much sooner than others, and the main reasons are only beginning to be unraveled by scientists.
The risk is small to none for the most fit and healthy people; but for others, the possibility of dying once contaminated is frightening. While there are only two deaths in children under 15 in the UK, there are more than 30,000 under 60.
We now know that being overweight, with the associated problems of type 2 diabetes, high blood pressure and heart disease, significantly increases the risk of the infection not surviving – presumably due to a weakened immune system.
If you combine this with the additional risk of an age-related decline in the immune system, the risk is even greater.
Every week the alarming truth about the Covid-19 coronavirus becomes clearer (stock image)
But now there seems to be another sinister element in the story that could explain why the number of deaths in men is two to one higher than in women, why overweight people are severely affected, why some ethnic minority groups are at a higher risk of complications walking and possibly why smokers seem to be protected from contracting the infection (and why they do badly when they get it).
Evidence is emerging of the role of a cell receptor called ACE2, to which Covid-19 attaches to infect our healthy cells. It is thought that the more of these receptors you have, the more entry points for the virus.
The ACE2 receptor has been identified as the major entry point for the potentially lethal severe acute respiratory syndrome (Sars) virus, of which this new coronavirus is the latest version. The receptors are found on cells in the nasal wall, lungs, pancreas, kidneys and intestines, and in the lining of blood vessels, in the heart muscle, and circulate on cells in the blood.
The variety of locations can help explain why those people with Covid-19 have had so many different symptoms, from loss of taste and smell to stomach problems such as diarrhea and heart problems after infection.
The normal role of the ACE2 receptor is in controlling blood pressure. It sits on our cells and is activated by a chemical messenger in our blood: when blood pressure is high, the receptor causes the blood vessels to widen.
Evidence emerges of the role of a cell receptor called ACE2, to which Covid-19 attaches to infect our healthy cells (stock image)
It interacts with another blood pressure regulator called simply ACE (this is not a receptor but an enzyme) that causes the blood vessels to contract. ACE2 and ACE work together to maintain blood pressure. It is this system that ACE inhibitors – antihypertensive and heart failure drugs taken by 15 percent of all adults in Britain – are designed to block the target, block the enzyme and prevent blood pressure from rising.
Obesity means more “entry points”
The Covid-19 coronavirus is designed to attach itself to ACE2 receptors as a key that opens a lock. It then enters the cell and reprograms it to make multiple copies of the virus.
It then destroys these depleted cells and releases billions of copies of the virus, which then infect other cells in the body.
This process causes a blockage of dead and decaying cells and an associated immune response (leading to the symptoms of the disease). For people with a high level of ACE2 receptors, there are many more entry points for the virus, so more chance of serious illness and worse results.
Studies have now drawn attention to groups that have more ACE2 receptors and those who have fewer. A study published last week in The Journal of the American Medical Association by doctors at Mount Sinai Hospital in New York found that four-year-olds had fewer ACE2 receptors in their noses than older adults.
And it seems that people with high blood pressure and heart disease produce more of these receptors while their bodies struggle to cope with a malfunctioning system. An international study published this month in the European Heart Journal looked at ACE2 receptor levels in 1,485 men and 537 women with heart failure – a leading cause of high blood pressure. In men, ACE2 receptors circulated in larger amounts in cells in their blood and even in the testicles.
We now know that being overweight, with the associated problems of type 2 diabetes, high blood pressure and heart disease, significantly increases the risk of not surviving the infection (stock image)
Another study, published last week in the journal Obesity, found that overweight people with lung disease chronic obstructive pulmonary disease (COPD), which is related to damage caused by smoking, “have more of the receptor or entry points needed for coronavirus infection in their lungs, “said lead author Dr. Andrew Higham, an infection, immunity and respiratory medicine researcher at the University of Manchester. “This means that these patients are at greater risk of developing Covid-19 due to a higher chance of infection.” There are 1.2 million Britons with COPD. It is clear that fat cells also produce more ACE2 receptors. “The more fat you have, the more ACE2 receptors you have,” said Professor Sanjay Sharma, a cardiologist at St George’s University Hospitals NHS Trust in South London and spokesperson for the European Society of Cardiology.
“Obesity is a chronic inflammatory condition,” he says, “and if you already have a mild inflammatory condition and a compromised respiratory system [because of the pressure your weight puts on your lungs and diaphragm], and you are attacked by a virus, you have a problem.
In addition, most of these people have high blood pressure and type 2 diabetes, which are also associated with high percentages of ACE2 receptors. These are some of the factors that help explain why obese people have fared worse and may partly explain why we have had more deaths than other countries because our obesity burden is higher. ‘
BUT LOSS OF WEIGHT CAN CUT NUMBERS
Losing weight reduces the amount of adipose tissue in the body and the number of ACE2 receptors, Professor Sharma explains, “It is an argument to curb obesity, because I suspect we will see many more viral pandemics.”
But Dr. David Gaze, a clinical biochemistry professor at the University of Westminster, says the picture is more complicated than the number of receptors. Their location also seems to matter.
Some studies on Sars in mice have shown that ACE2 receptors had done their job and caused the blood vessels to widen, reducing the level of injury to the lungs. But another study in mice had shown the opposite effect. “It appears that there is a difference in ACE2 receptor conditions depending on whether the receptors are found in the soluble form – i.e. in the blood – or the ‘bound’ receptor form in organs,” he told Good Health.
“The Covid-19 virus is relatively new to the human population. We never knew before that the ACE2 receptor was needed to get the virus into cells. There may be different worldwide distributions of ACE2 receptors between different populations and ethnic groups, but we don’t know. ‘
Losing weight reduces the amount of adipose tissue in the body and the number of ACE2 receptors, explains Professor Sharma (stock image)
Of the nearly 37,000 deaths in Britain attributed to Covid-19 so far, more than a third belong to the Black, Asian and Ethnic Minorities (BAME), although they make up only 14.5 percent of the population.
Scientists at the University of Hawaii are investigating whether people from some ethnic groups have more ACE2 receptors.
The British Heart Foundation has pointed out that South Asians have a higher risk of heart disease, while those with African and Afro-Caribbean backgrounds are at greater risk for high blood pressure problems and strokes, as well as type 2 diabetes.
Professor Sharma suggests that a greater tendency to develop these problems may be due in part to the fact that ethnic minority communities have previously grown up on traditional, healthy whole foods, and that their metabolic systems are not well equipped for attack by the high sugar, heavily processed diet common in the UK.
“People of Asian descent tend to develop heart disease at a lower BMI stage of obesity,” he says. “In places like India, their diets have started to include foods like McDonald’s and KFC, and the prevalence of high blood pressure and type 2 diabetes is skyrocketing.”
However, it is too early to know whether the levels of ACE2 receptors play a role in the higher mortality rate of Britons with a BAME background, says Simon Clarke, a virologist at the University of Reading.
GOOD NEWS (AND BAD) FOR SMOKERS
Another twist in the story is the potential role of ACE2 receptors in protecting smokers from catching Covid-19.
A study of 1,000 Covid-19 patients in China, published in the New England Journal of Medicine in March, found that only 12.6 percent of them smoked, although 28 percent of the population smokes.
A similar study in France of 11,000 Covid-19 patients found that only 8.5 percent smoked, while smokers make up 25.4 percent of the population.
Professor Florence Tubach, head of public health at Pitié-Salpêtrière Hospital in Paris, conducted further research and said that Covid-19 infected smokers were five times less likely to develop symptoms than non-smokers and four times less likely to develop symptoms. hospitalized. Trials are planned to see if nicotine patches can prevent Covid-19 infection.
Although smokers have higher levels of ACE2 receptors, the theory is that nicotine binds to them, preventing coronavirus from using them to enter cells, thereby protecting smokers from coronavirus infection.
But other research has shown that smokers who are infected with Covid-19 will survive in the hospital once. Some doctors have pointed out that because cigarettes are removed immediately as soon as a patient enters the hospital, the potential nicotine benefit is lost.
News of the investigation prompted a rush to buy nicotine patches and chewing gum, causing the Paris authorities to limit sales earlier this month.
But fellow researcher Professor Bertrand Dautzenberg warned that nicotine patches for non-smokers are not a good idea. “A smoker easily tolerates a dose of nicotine that is a hundred times higher than the dose that would make someone who has never smoked consistently nauseous,” he told Le Figaro newspaper.
And it should be emphasized that most experts believe that the deadly effects of smoking outweigh the potential benefits of nicotine, although research may show that nicotine patches alone may be beneficial.
LINK TO SERIOUS COMPLICATIONS
Other rarer complications caused by the virus being held at ACE2 receptors are strokes.
Doctors from University College Hospital in London have reported a series of six inexplicable strokes associated with a Covid-19 infection, suggesting that when ACE2 receptors are blocked in the blood vessels, abnormal clotting occurs.
“Some Covid patients wake up from a ventilator and don’t remember anything, suggesting there may be mini blood clots in the brain,” said Professor Sharma.
“There is no doubt that there is a difference in people’s responses to Covid-19 and we don’t know enough about it yet.”
DO BLOOD PRESSURE PILLS INCREASE YOUR RISK?
ACE2 receptors are proteins that viruses such as Covid-19 use to break into our cells and infect us. For this, different viruses use different receptors.
The normal role of the ACE2 receptor is in blood pressure regulation and indeed, ACE inhibitory drugs are taken by 15 million British for high blood pressure and heart failure.
Experts warn patients that in no case should they stop taking prescribed heart medications (stock image)
There is some concern that ACE-inhibiting drugs may be a problem for people with Covid-19 – because, by blocking the enzyme, ACE is believed to increase the number of ACE2 receptors because it disrupts the natural signaling system.
However, experts warn patients that under no circumstances should they stop taking prescribed heart medications.
“ACE inhibitors and ACE receptor blockers are not associated with an increased risk of Covid-19 infection or infection severity, or death risk in patients who already have Covid-19,” said Francesco Cappuccio, a professor of cardiovascular medicine and epidemiology at Warwick University and spokesperson for the British and Irish Hypertension Society. “People they have been prescribed should keep using them.”