New insights from studying gut microbes in fish suggest the makeup of these bacteria could determine our life expectancy, according to research published in eLife.
The results* show that gut bacteria play a direct role in the aging process, and that lifespan can be extended by transplanting the same bacteria from a younger animal. This raises the intriguing possibility that altering these microbes could prevent or halt the onset of age-related diseases.
Lead author Patrick Smith, postdoctoral researcher at the Max Planck Institute for Biology of Ageing in Germany, says: “Previous research has shown that large changes in the makeup of the gut bacterial community are a hallmark of aging, but the role that these groups of microbes play in the aging process has largely been unexplored.”
One of the barriers to investigating this was the lack of animal models with a sufficiently short lifespan. But Smith and his colleagues identified the turquoise killifish, which lives for only a few months in captivity, as a potential solution. Similar to other animals, the killifish displays many signs and symptoms of aging, including the development of neurodegenerative diseases. Until now, however, little was known about the diversity of its gut microbes and whether they would sufficiently reflect that of humans.
The team first used a special sequencing technique to identify and compare the bacteria in the killifish gut, and were surprised to find diversity similar to other longer-lived animals, including zebrafish, mice and humans. Moreover, the four most abundant groups of bacteria in the killifish gut are also the four largest groups of bacteria found in the human gut.
The team then used the killifish to find out what changes occur in the gut microbe population during aging. They analysed the microbes of six-week-old fish and compared them to 16-week-old fish. This showed the diversity of bacteria was much lower in the older fish, even though the total number of bacteria in the gut stool was the same, mirroring the pattern seen in humans where aging is associated with a less diverse microbial community.
“We next wanted to see if recolonising the older fish with the gut microbes of younger fish could extend their life,” says senior author Dario Riccardo Valenzano, Group Leader at the Max Planck Institute for Biology and Ageing.
They treated middle-aged (9.5-week-old) fish with antibiotics to clear out existing gut bacteria, and then applied the gut content of fish the same age, or six weeks old. They saw that treating the older fish with with the gut content of six-week-olds dramatically extended their lifespan.
“This is the first evidence that the transfer of gut microbes in the context of normal aging can significantly prolong lifespan in a vertebrate. As such, it presents a potential new intervention to enhance lifespan in other organisms,” concludes Valenzano.
*These results were in part published as a preprint in bioRxiv on March 27, 2017, and made available at http://www.biorxiv.org/content/early/2017/03/27/120980.
eLife is a unique collaboration between the funders and practitioners of research to improve the way important research is selected, presented and shared. eLife publishes outstanding works across the life sciences and biomedicine – from basic biological research to applied, translational and clinical studies. All papers are selected by active scientists in the research community. Decisions and responses are agreed by the reviewers and consolidated by the Reviewing Editor into a single, clear set of instructions for authors, removing the need for laborious cycles of revision and allowing authors to publish their findings quickly. eLife is supported by the Howard Hughes Medical Institute, the Max Planck Society and the Wellcome Trust. Learn more at elifesciences.org.
About Max Planck Institute for Biology of Ageing
The Max Planck Institute for Biology of Ageing investigates the natural ageing process with the long-term goal to pave the way towards increasing health during ageing in humans. It is an institute within the Max Planck Society, which is one of Germany’s most successful research organisations. Since its foundation in 2008 the institute is an integral part of a local life science cluster that pursues ageing research.