A receptor in the thymus slows immune aging

The thymus is a small organ behind the breastbone. It is active early in life and trains T cells, a critical type of immune cell. With age, the thymus gradually shrinks as fatty tissue replaces its functional cells. This is called involution. The result is a weaker immune system in later life: fewer new T cells and reduced protection against infections and possibly cancer.

The researchers, publishing in Aging Cell, focused on GPR40, a receptor found on thymic epithelial cells. Epithelial cells are the structural support cells that keep the organ functioning. They activated GPR40 using a compound called GW9508 in 17-month-old mice, an age that corresponds to advanced aging in this model.

Low dose, notable result

The lowest dose of GW9508 proved most effective. Treated mice had thymuses that were on average roughly 50 percent heavier than those of the control group, a difference that reflects more active tissue. Multiple types of epithelial cells increased in number, as did several T cell subsets. When the researchers blocked GPR40, the positive effects disappeared, confirming the receptor as the driver of the result.

Additionally, GW9508 reduced the number of senescent cells (cells that stop dividing but are not cleared, a process known as cellular senescence) in the thymus. Blood and kidney markers showed no signs of toxicity.

A long road to human application

This is mouse research, and that warrants a firm caveat. Results in mice do not reliably translate to humans, and the thymus functions somewhat differently across species. Still, the study adds a concrete molecular target to the growing field of thymus rejuvenation. Whether GPR40 activation can also slow thymic aging in humans is a question that future research will need to answer.

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