A gut bacterium in centenarians shields the intestinal wall

The intestinal wall acts as a filter, letting nutrients through while keeping harmful bacteria and waste products out of the bloodstream. With age, this filter becomes less effective. The wall grows more permeable, allowing unwanted substances to enter the body and fuel chronic inflammation, a process sometimes called inflammaging. This contributes to a range of age-related diseases.

The researchers analysed the gut microbiome of centenarians using a network approach rather than the standard abundance-based method. Instead of simply counting which bacteria are present, they examined how bacteria interact with each other. Clostridium scindens emerged as a keystone taxon: a bacterium that stabilises the network regardless of its own numbers.

From tryptophan to repair

How does the bacterium achieve this? Clostridium scindens converts the amino acid tryptophan into indole-3-acetic acid (IAA), a compound that activates the AHR receptor in gut cells. This activation increases production of claudin-10, a protein that keeps the junctions between intestinal cells tightly sealed. In aged mice, intestinal permeability was measurably reduced by administering either the bacterium itself or IAA alone.

Cautious optimism

These findings are preliminary. The experiments were conducted in mice, and whether the same mechanism applies in humans has not yet been demonstrated. The higher levels of Clostridium scindens in centenarians also reflect an association, not proof of causation. From a longevity perspective, the results are nonetheless noteworthy: a specific bacterium that can, via a defined molecular pathway, dampen one of the earliest drivers of aging offers a concrete target for future research into probiotic or dietary interventions.

The study was published in iMeta.

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