The mTOR inhibitor rapamycin slows the progression of aging in mice. The may largely be a result of upregulated autophagy, as is the case for many other means of slowing aging in short-lived species, including calorie restriction. If an intervention slows aging generally, the odds are fairly good that any specific aspect of aging will also be slowed. Here, researchers show that rapamycin treatment improves the outlook for age-related periodontitis in mice.
Periodontal disease, also known as gum disease, is a common problem in older adults that causes painful inflammation, bone loss, and changes in the good bacteria that live in the mouth. Yet there are no treatments available beyond tooth removal and/or having good oral hygiene. Rapamycin is an immune-suppressing drug currently used to prevent organ rejection in transplant recipients. Previous studies in mice have also suggested that it may have life-extending effects, which has led to interest in studying the drug's effects in many age-related diseases.
To find out if rapamycin might slow periodontal disease, researchers added the drug to the food of middle-aged mice for eight weeks and compared their oral health with untreated mice of the same age. Similar to humans, mice also experience bone loss, inflammation, and shifts in oral bacteria as they age. Using a 3D-imaging technique called micro-computed tomography, the team measured the periodontal bone, or bone around the tooth, of the rapamycin-treated and untreated mice. They showed that the treated mice had more bone than the untreated mice, and had actually grown new bone during the period they were receiving rapamycin.
The work also showed that rapamycin-treated mice had less gum inflammation. Genetic sequencing of the bacteria in their mouths also revealed that the animals had fewer bacteria associated with gum disease and a mix of oral bacteria more similar to that found in healthy young mice. While rapamycin is already used to treat certain conditions, it can make people more susceptible to infections and may increase their risk of developing diabetes, at least at the higher chronic doses typically taken by organ transplant patients. Clinical trials in humans are needed to test whether rapamycin's potential oral health and other benefits outweigh its risks.