A transplant drug with anti‑ageing properties has been shown to rejuvenate the oral health of old mice. The drug, called rapamycin, regenerated the bone in which teeth are embedded, restored the mouth microbiome to a youthful state and reduced inflammation.
It is the first time any treatment has been shown to rejuvenate oral health, says team leader Matt Kaeberlein at the University of Washington in Seattle. “We could actually see spots where new bone was growing around the teeth.”
Two-thirds of elderly people have gum disease and no existing treatment reverses the process, says Kaeberlein. What’s more, gum disease is linked to a higher risk of other conditions, including dementia, diabetes and heart disease.
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Some researchers think gum disease is the cause of Alzheimer’s, as 91av reported earlier this year. This suggests that restoring oral health could have much wider benefits. “It’s clear to me that this could be immensely important,” says Kaeberlein.
But it isn’t clear if rapamycin has the same effect in humans. Even if it does, the drug can have many undesirable side effects. It suppresses the immune system, which is why its main use is in preventing transplanted organs from being rejected.
Rapamycin has also attracted interest for its anti-ageing effects: it can extend the lives of several animals, including mice and fruit flies, by around 10 per cent. Kaeberlein started looking at its effect on the mouth when Jonathan An, who had previously studied dentistry, joined his team.
The researchers found that mice given rapamycin all their lives had more bone around their teeth. So they gave mice aged 20 months – elderly in mouse terms – food with added rapamycin for eight weeks, and compared their oral health with that of mice not given the drug.
The team saw bone growth in the mice’s mouths, as well as a decline in disease-associated bacteria that become more common in older animals. These include Porphyromonas gingivalis, which is a suspected cause of Alzheimer’s.
The findings are fascinating, says João Pedro de Magalhães, at the University of Liverpool, UK. “The big question is whether it could have the same effect in people,” he says.
Several groups are creating variants of rapamycin that are designed to minimise undesirable effects, and some are being trialled in people.
It is possible these drugs will have the same benefits for oral health that were seen in mice.
Kaeberlein is carrying out another mouse study designed to reveal if applying rapamycin just to the mouth, rather than to the entire body, has the same effect. He also hopes to run a trial in people. Using a lower dose than that given to people with transplanted organs might minimise side effects, he says.
He doesn’t plan to study those already on the drug. People needing transplants are seriously ill and are given many different drugs, so there are too many confounding factors, he says.
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