Thymus hormone curbs aging inflammation in cancer
The thymus shrinks after your twenties and gradually loses its function. But a hormone it produces, thymulin, remains active in older age. And it appears able to reduce chronic inflammation in older mice with cancer.
Chronic low-grade inflammation (inflammaging) promotes tumour growth and makes cancer therapies less effective. Researchers searched for circulating factors that could dampen that inflammation. They identified thymulin, a hormone produced by the thymus gland. The study, published in Aging, shows that thymulin reduces inflammation in mouse models and makes cancer therapies more effective.
Adjusting old blood
The researchers connected the circulation of young and old mice (parabiosis). In old tumour-bearing mice, pro-inflammatory cells in the blood subsequently declined sharply. This improved their survival and slowed tumour growth. In the same experiments, however, young mice suffered: their tumour growth accelerated. This illustrates both the power and the two-sidedness of circulating factors. Thymulin was identified as one of the factors that is deficient in old blood and that could reduce inflammation when administered.
Not yet proven in humans
The findings are so far limited to mouse models and cellular experiments. Whether thymulin has comparable effects in humans has not yet been answered. Thymus involution, the gradual shrinkage of the thymus with age, reduces thymulin production. Restoring that production is therefore a potentially interesting target for future research. Whether thymulin supplementation is safe and effective in humans must be established in clinical trials.
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