Gut stem cells age through an inflammation signal

As people age, the intestinal wall becomes less efficient at renewing itself. That raises the risk of infections, inflammation and metabolic problems. What triggers this decline in intestinal stem cells has been unclear until now. The study, published in Nature Aging, points to TNFR1, a receptor on cells that lets in the inflammatory protein TNF.

From inflammation to energy loss

When TNFR1 is activated, it suppresses a key energy process in stem cells called fatty acid oxidation (beta-oxidation). This process is normally essential for intestinal stem cells to function and renew the gut lining. Without adequate energy production, stem cells cannot maintain the tissue. The result is a cycle: more inflammation leads to less energy in stem cells, which leads to poorer gut function, which feeds further inflammation.

Young blood restores older tissue

The researchers also ran a striking experiment. They connected the circulation of old and young mice, a technique called parabiosis. After this, the intestinal stem cells of the old mice showed measurable improvement. This suggests that the inflammatory proteins circulating in older animals drive the stem cell decline, and that removing them helps. From a longevity perspective, this is noteworthy: it implies that systemic inflammation, not just local aging of the intestinal cells themselves, is what ages the gut. The researchers stress that these are preliminary findings in mouse models, and that translation to humans requires further study.

Because the effect is transferable through the bloodstream in both directions, TNFR1 signalling becomes a potential therapeutic target. Whether this holds in humans is not yet known. But the finding again places systemic, chronic low-grade inflammation (inflammaging) at the centre of organ aging.

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