The secret to becoming a centenarian may lie in the immune system. The increase in human life expectancy has been accompanied by an increase in the number of people living to 100 years or more. Researchers have found that centenarians have a unique composition and activity of their immune cells, which gives them an immune system that helps them live longer. Scientists believe these findings could be used to develop treatments for healthy aging.

The life expectancy of human beings on our planet has more than doubled since 1900. Global life expectancy has increased from 31 years in 1900 to 73.2 years in 2023, and is expected to increase further to reach 77.1 years in 2050. The number of people reaching the age of 100 or more is also increasing. Researchers estimate that there were approximately 450,000 centenarians worldwide in 2015, and that number is expected to reach 3.7 million by 2050. In the early 2000s, research conducted estimated that the number of people living up to at age 100 or more would more than quintuple between 2005 and 2030.

We still don’t know what allows some people to live to be 100, while others don’t. A new study from Boston Medical University (US) helps answer this question by finding that centenarians have unique immune cell composition and activity, giving them a highly functional immune system and allowing them to to live longer. Scientists believe that these results could be used to develop therapies for healthy aging. The study was recently published in the Lancet eBioMedicine journal.

What happens to our immune system as we age?

With age, all parts of the body undergo changes, including the immune system. The first is immunosenescence, which is the process of age-related immune dysfunction. Changes in the composition and function of our immune system over time can therefore lead to poor immune function in older people.

And this is closely linked to people’s susceptibility to infections, autoimmune diseases, and even various types of cancer. There is also the issue of “inflammaging,” which is a term used to describe age-related increases in inflammation due to elevated levels of pro-inflammatory markers in the blood and various body tissues. ‘body.

It is an important risk factor for all kinds of diseases, including neurodegenerative processes such as Alzheimer’s disease, for example. So there’s a lot to look at when it comes to immune function over time and how our immune system changes as we age, which can either make us more vulnerable or protect us.

The examination of an elite immunity

According to the lead author of this study, she and her team decided to study the immune system of centenarians because age causes changes in our immune system, especially in its function and cellular composition, and these changes can lead to age-related diseases. Many centenarians experience delays in the onset of age-related diseases, suggesting the presence of elite immunity that remains highly functional even into very old age.

For this study, the researchers performed single-cell sequencing on a category of immune cells called peripheral blood mononuclear cells (PBMC) from blood samples taken from seven centenarians participating in the New England Centenarian Study.

The researchers used single-cell data and applied new computational methods to analyze the immune cells that circulate in the immune system throughout human life. They looked at differences in the presence of specific immune cell types in young and very old people and we found cell type-specific changes in aging and very old people. They also took the same cell types and explored gene expression differences between ages to find different extreme longevity gene expression patterns that change with age but are also unique to extreme old age.

Unique cell types in centenarians

After analysis, the researchers confirmed observations made in previous studies on aging, which identified compositional and transcriptional changes specific to unique cell types found only in centenarians and which reflect an immune response. normal. They also found that centenarians displayed cell-type signatures specific to exceptional longevity, both in genes showing age-related changes and genes expressed only in centenarians.

The researchers weren’t surprised to find genes that change with age in centenarians, since this is an aging population. What surprised us were the different patterns of aging identified, including aging-specific genes whose expression levels change with age, but not with extreme longevity in various cell populations.

These results can serve as a basis for exploring potential drivers of extreme old age, which could lead to the discovery of therapies for healthy aging. Researchers would like to study longitudinal changes in the immune cells of centenarians and younger people to better define the protective factors of extreme longevity that drive the beneficial health outcomes seen in these people.

New therapies for age-related diseases

The potential lessons that can be drawn from this study relate to what makes us more resilient. Understanding the immune changes that come with aging is important to help people live longer. And many people want to live longer if they can also be healthy. If we can figure out what creates this immune resistance in people who live past 100, it may lead to treatments that can help people live longer. Or, if there are certain healthy behaviors that promote that resilience, that would also help us.

However, this is very preliminary research, as this study was small, and should lead to further studies to help healthcare professionals better understand this immune resilience. Further research is needed to understand the effect of these immune patterns on longevity. Is there something in the family history of centenarians or other things that have happened in their lives, exposure to certain things that might have altered their immune system? Knowing more about it could lead to new therapies or new ways to improve the immune system.

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