Forgotten hormone may hold key to healthier ageing, study suggests

A small organ long overlooked by the medical community could play a crucial role in controlling age-related inflammation, according to new research in mice.

The thymus, located between the lungs and roughly the size of a dried apricot, is best known for helping the body produce infection-fighting immune cells known as T cells during childhood. Because the organ shrinks after puberty, scientists have traditionally believed its importance to the immune system also declines with age.

However, a new study published in Nature Communications suggests the thymus continues to play an important role later in life, as an article by the Scientific American outlet sheds light on.

Researchers found that thymulin, a hormone produced by the thymus, appears to suppress age-related inflammation in older mice.

The findings raise the possibility that thymulin could eventually help researchers develop new cancer therapies and treatments for diseases linked to "inflammaging"—the chronic, low-grade inflammation associated with ageing—if the results can be replicated in humans.

The hormone thymulin was first discovered around 50 years ago, but its role in ageing has been largely unexplored.

"The hormone thymulin was discovered some 50 years ago, but its role in ageing has been “somewhat overlooked,” says Fumito Ito, the study’s senior author and an immunologist at the Keck School of Medicine of the University of Southern California.

Previous studies have linked thymus health with immune function and longevity. Earlier research involving approximately 27,000 patient records found that better thymus function was associated with longer lifespans and lower rates of lung cancer and cardiovascular disease. It also found a correlation between thymus health and lower levels of inflammation, although the biological mechanism remained unclear.

The new research may help explain that relationship.

"The new findings may provide a “causal link” between the thymus and longevity," says Fumito Ito, the study’s senior author and an immunologist at the Keck School of Medicine of the University of Southern California.

In the study, mice with higher levels of thymulin had myeloid immune cells that produced lower levels of cytokines—proteins that help the body fight infection but can also contribute to inflammation when present in excess.

Researchers also found that older mice with cancer responded better to treatment after receiving thymulin. The animals experienced slower tumour growth and improved responses to immunotherapy.

"The results could one day improve cancer therapies for humans," Ito says.

“Our study shows that this hormone can slow down tumour growth, improve survival and also enhance the treatment efficacy of cancer immunotherapy,” he says.

While the findings are limited to animal studies, the researchers say they offer fresh evidence that the thymus remains biologically important long after childhood and could become a target for future therapies aimed at reducing inflammation and improving healthy ageing.

By Nazrin Sadigova