Excellent, essential organ for the production of immune T cells, loses effectiveness with age.
Scientists managed to temporarily restore the production of immune cells in elderly mice, using the liver as a substitute for the thymus, an essential organ of immunity that loses effectiveness with age.
Over the years, the immune system gradually loses its effectiveness, making the body more vulnerable to infections, cancer and other diseases.
Now, a team of scientists from MIT and Harvard has discovered a new way to rejuvenate one of its essential components, with the potential to improve health in old age, according to investigation published in the journal .
The role of the thymus in immunity
The research, led by a team from MIT’s Broad Institute and Harvard University, focused on the thymus, a small organ located behind the sternum in the upper chest. The thymus is crucial for the development of T cells or T lymphocytes, a type of immune cell responsible for identify and eliminate threats such as viruses, bacteria and cancer cells.
From early adulthood onwards, the thymus begins to shrink and lose activitywhat limits the production of new T cells and contributes to the weakening of the immune system.
Transform the liver into a “substitute” for the thymus
In experiments with mice, researchers were able to reuse part of the liver to temporarily perform some of the functions of the thymus.
“As we age, the immune system begins to decline. We wanted to understand how to maintain this type of immune protection for longer, and that’s what led us to think about ways to boost immunity,”
Proteins that disappear with age
In the first phase of the experiment, the team compared the immune systems of young and old mice. This analysis allowed us to identify three essential signaling proteins, whose levels decrease with age: DLL1, FLT3-L and IL-7. These proteins play a central role in the transformation of immature cells into functional T cells and their maintenance.
Based on these results, the researchers developed a treatment with mRNA, the messenger ribonucleic acid that functions as a set of instructions for the production of proteins. The treatment was administered through repeated injections into the livers of aged mice.
The choice of the liver was not accidental: it is an organ with a high capacity for protein production, even at advanced ages.
Results: more T cells and better immune response
After four weeks of treatment, elderly mice showed significant increases in the number and diversity of T cells. They also responded more robustly to vaccines and showed greater ability to fight tumors, signs of a stronger and more functional immune system.
One aspect that scientists highlighted is that the Liver-induced increase in T cell production was temporary. This reduces the risk of excessive stimulation of the immune system, which could cause inflammation or lead the body to attack its own tissues.
Despite the encouraging results, scientists emphasize that it is still necessary to demonstrate the feasibility of this approach in humans. Next steps include testing on other animals and exploring different signaling proteins and immune cell types.
There have been other attempts to rejuvenate the production of T cells, namely through the direct administration of immune stimulants into the bloodstream, often with significant side effects and risks. The results now published suggest that this liver-based strategy may prove to be a safer and more effective alternative.
“If we can restore something essential like the immune system, we hope to be able to help people stay disease-free for longer,” says Zhang.
