Like all cells in our body, immune cells also age. It is no coincidence that over time our immune system “weakens” and is less and less able to fight infections, cancer and other diseases. Until now it was thought that this aging process, known as cellular senescence, was an inevitable consequence of old age and infections. But a study published in the journal Nature Cell Biology suggests that the biological clock hands of immune cells can be moved backwards and, in part, do so spontaneously.
The “transfer” of longevity
The study was carried out by University College London, the University of Oxford, IRCCS Saint Lucia and Sentcell ltd, an innovative company focused on cell rejuvenation. Scientists have discovered a mechanism that immune cells use to stay “young” longer: a transfer of longevity from one cell to another. This mechanism could also be the key to making diseases such as cancer and dementia treatable. Or even to lengthen the effectiveness of a vaccine, such as that against Covid-19, without necessarily having to undergo booster injections.
Exchange between cells
Researchers have found that one immune cell can hand over a piece of its “youth” to another. More precisely, an antigen presenting cell (APC), made up of B cells, dendritic cells or macrophages, and which has the role of triggering the immune response of T lymphocytes, the “soldiers” of our immune system, can extend longevity of the latter. And it does this via extracellular vesicles, small particles that facilitate communication between cells. These vesicles would transfer the telomeres, ie the “caps” located at the end of the chromosomes, from one cell to another in order to protect them.
Telomeres age as they get shorter
In T lymphocytes, as in most cells, the telomeres become shorter and shorter with each subsequent cell division. When telomeres reach a critical length, the cell stops dividing and goes into senescence. The process of eliminating the “old” cell is then activated. Telomere wear has been described by scientists as one of the “hallmarks of aging” and, when the immune system no longer functions effectively, this leads to chronic infections, cancer and death.
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Telomeres transferred which become stem cells
In the study, the researchers studied the immune response of T lymphocytes against a microbe in vitro and unexpectedly observed a telomere transfer reaction between two types of white blood cells, through the extracellular vesicles. With telomere transfer, the recipient T lymphocyte becomes long-lived and acquires cellular memory characteristics and properties similar to those of stem cells. In this way, the T lymphocyte can protect the body from an infection in the long term.
Extraordinary implications
According to the researchers, the transfer reaction stretched some telomeres by about 30 times more than the telomerase enzyme, previously considered the only one capable of keeping the telomeres of some cells intact or almost intact, including those of the immune system. “The telomere transfer reaction between immune cells – he explains Alessio Lannahonorary professor at UCL and CEO of Sentcell Ltd – adds to the Nobel Prize-winning telomerase discoveries and demonstrates that cells are able to swap telomeres to regulate chromosome length before telomerase action begins. ” .
“Cure” aging
The implications of this discovery could be extraordinary. “It is possible that aging can be slowed or cured simply by transferring telomeres,” speculates Lanna. The telomeric vesicles isolated by the researchers exhibited anti-aging properties in both human and mouse cells. In the future, according to the researchers, we could try to administer them to extend immune protection, prevent or control an infection, independently or in combination with a vaccine. Thus, new generation anti-aging drugs could be created that can stimulate the telomeric transfer reaction directly in humans, enhancing their defense mechanisms against external threats, such as the Sars-CoV-2 virus.
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