Coronavirus: how our immune system ages and how we can stop this process

However, the age of the immune system does not necessarily match chronological age. And as we get older, this discrepancy can become even wider.

“We can have individuals who chronologically are 80 years old and have an immune system that looks like a 62-year-old person. Or quite the opposite: a 60-year-old person whose immune system looks like that of a person of a much older age,” he explains. to BBC Mundo Shai Shen-Orr, immunologist at the Israel Technion Institute of Technology.

What’s interesting, moreover, is that we can slow down your aging (or possibly reverse your age) by following a series of simple steps.

But before we see how to achieve it, let’s remember how it works and how and what deteriorates with age.

The immune system has two arms, each one made up of different types of cells.

On one side is the call innate response, which is the first line of defense that is activated almost immediately when it detects the presence of a foreign organism.

This answer contains “neutrophils, that attack mainly bacteria; monocytes, which help organize the immune system, alerting other immune cells that there is an infection, and then there are the NK (the asesin cells), whose job is to fight viruses or cancer. These three cells they don’t work so well when we get older “, Janet Lord, director of the Institute of Inflammation and Aging at the University of Birmingham, in the United Kingdom, explains to BBC Mundo.

On the other hand is the adaptive response, composed of lymphocytes T y B that fight a specific pathogen. This response takes a few days to kick in, but once it does, it will remember the pathogen for the future and fight it again, if it reappears.

“When you get old, you produce fewer new lymphocytes, which are what you need to fight a new infection like SARS-CoV-2, “says Lord.

“And even the ones your body created in the past to fight another infection don’t work very well either,” he adds.

That is, aging causes a decline in all functions of the immune system.

The innate response produces a little more cells but these do not work as well, and the adaptive response produces fewer B lymphocytes (which are made in the bone marrow and are responsible for producing antibodies) and fewer T lymphocytes (that are produced in the thymus and identify and kill pathogens or infected cells).

The decrease in T cells is due to the fact that “the thymus begins to shrink at 20 years of age. It gets smaller and smaller and when you reach 65 or 70 years, only 3% of it remains (in the body) “says Lord.

The loss of cells that store the memory of pathogens causes us to lose not only the ability to respond to infection, but also the vaccines that prevent them as we age.

In the case of the flu vaccine, for example, “40% of adults over the age of 65 do not generate a response to the vaccine,” says Shen-Orr.

Another problem is that age generates more inflammation in blood and tissues, something that in English is known as inflammaging (a combination of the words inflamation and aging, ageing).

“In addition to not functioning optimally, cells of the immune system tend to cause inflammation, which leads to numerous diseases,” Lord explains.

All these changes that occur as we get older, “make it more difficult for us to recover from an infection or injury, and that some infections can become chronic,” says Encarnación Montecino, a researcher at the University of California, in the United States.

“Infections that were under control can reappear (such as herpes zoster, or tuberculosis), increases the susceptibility to new pathogens (flu, pneumonia) and the incidence of cancer,” he adds.

Although with the advancement of the years we all suffer a deterioration whose trajectory is foreseeable, what varies enormously is the rhythm in which each individual does, influenced by genetics, but also – and to a large extent – by Lifestyle.

Until recently it was not possible to determine the immune age, but the investigations of Shen-Orr and his team, in collaboration with Stanford University, in the United States, managed to create a method to obtain this information, crucial to arrive at successful treatments.

“By analyzing the composition of 18 types of cells of the immune system and the expression of genes in a blood sample, we can establish at what stage of the aging process a person’s immune system is,” explains Shen-Orr.

The variation in the speed of the deterioration process is also linked to the gender difference.

“While the two sexes age, due to the specific effects of sex hormones, some of the parameters age at different rates in men and women,” says Montecino.

For example, in women “menopause produces a leveling off of the protective effects of estrogen.”

The good news, as we mentioned in the beginning is that the aging process can slow down.

The key is to stay physically active: “Nowadays, sitting for a long time is for the body what smoking was before,” explains Lord, comparing it to this habit that many people have already abandoned.

“In studies with people who were active from young to old – cyclists up to 80 years old who continued to do 100 km or 150 km a week – the results were incredible,” says Lord.

“They had many T cells and the thymus hadn’t shrunk“.

“In another study that monitored the number of steps per day, they found that if you do 10,000, your neutrophils look like those of a 20-year-old.”

“I thought that this figure was an invention of the people who sold devices to measure them, but when we did the study I was totally surprised”, confesses Lord.

It all depends on the physical state from which one starts, but basically it is doing simple exercises such as standing up and down on tiptoes, climbing stairs and lifting a little weight with the arms if one is older or not in good physical condition, and doing vigorous exercise for short periods of time, if you are fit.

“Just do something. Anything you can do helps.”

It is one thing to slow the rate of aging and another to reverse the process.

The analyzes carried out by the Birmingham researcher and her team have not focused on that, but Lord notes that a small study (with 12 participants) published last year showed, for the first time, that giving three different drugs could be reversed immune age and biological age in 2 years.

Shen-Orr mentions a study on a drug that he and his team are working on but whose results have not yet been published, which also shows that reversal is possible.

“We saw a reduction (in immune age), but we do not yet know if this is going to be maintained permanently,” he says.

But stopping the deterioration is a more than important step.

Other factors that can help in this regard are a varied diet, rich in fiber, with fermented foods and little red meat to maintain the health of the intestinal microbiota (a field of research that is still in its infancy), and an optimal sleep of about 6 1/2 hours or 7.

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