Des chercheurs expliquent le « coup de vieux » brutal dès 70 ans

Researchers explain brutal ‘aging’ from the age of 70

Researchers reveal why people suddenly become more vulnerable at age 70. They discovered a “catastrophic change” in the composition of blood cells, paving the way for new treatments to slow the aging process.

Cambridge researchers have discovered a process that leads to a “catastrophic” change in blood composition in old age, increased risks of leukemia and anemia, and reduced the effectiveness of white blood cells in fighting infection.

Scientists believe similar changes occur in all organs of the body, from the skin to the brain, which could explain why people often age in good health for decades before experiencing a faster decline in their 70s or 80s.

“What’s exciting about this work is that there can be a common set of processes at work,” says Dr Peter Campbell, lead author of the study and chair of ‘Cancer, Aging and Somatic Mutation’ at the Sanger Institute in Cambridge. “Ultimately the goal will be to slow down or interfere with the aging process, but at least we see the possibility of using it to measure biological age.”

A set of processes at work

Aging is a complex process, but many scientists suspect that the gradual accumulation of mutations in cells gradually degrades the body’s ability to function properly. The latest research suggests that this reasoning is flawed, or at best incomplete, and instead blames “selfish” cells that have become dominant in aging.

Working with scientists from the Wellcome-MRC Cambridge Stem Cell Institute, Dr. Campbell and colleagues studied blood cells from people of all ages, from newborns to their 70s and ages. They found that adults under the age of 65 had a wide variety of red and white blood cells produced by a variety of 20,000 to 200,000 different types of stem cells in their bone marrow.

The sudden collapse of the stem cell stock

Among those over 65, the picture was quite different. About half of their blood cells came from 10 or 20 separate stem cells, which greatly reduced the diversity of a person’s blood cells, with consequences for their health.

In their Nature article, the researchers explain that if stem cells involved in blood production mutate over time, most of those changes are harmless. But problems arise when rare “experimental” mutations speed up the growth of stem cells, often producing lower quality blood cells in return. When a person is in their 30s or 40s, the abnormal stem cell growth advantage makes little difference, but by age 70 and older, these rapidly growing cells dominate blood cell production.

“Exponential growth explains why such a sudden change in vulnerability occurs after age 70, and why it hits aging at this age,” Campbell said. Rapidly growing blood stem cells are linked to leukemias and anemia, but they also make people less resistant to infections and medical treatments such as chemotherapy.

“What we know from other organ systems is that many of the same observations apply,” Campbell added. The researchers now plan to look at the same process in the skin to understand why aging causes wrinkles and slows healing.

Chronic inflammation, smoking, infection and chemotherapy can all produce stem cells with oncogenic mutations, said Dr Elisa Llorente, associate professor at the Wellcome-MRC Cambridge Stem Cell Institute and co-lead researcher on the study.

“We would expect these factors to also lead to the reduced diversity of blood stem cells associated with aging,” she said. “It is possible that some factors also slow this process down. We now have the exciting task of understanding how these newly discovered mutations affect blood function in the elderly, so that we can learn how to reduce disease risk and promote healthy aging.”

with Watchman

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