Microbiome and aging
Bacteria in the gut can show Your true Age
The researchers concluded that the microbiome is a surprisingly accurate biological clock capable of predicting the age of most people with an accuracy of several years, writes Science (Emily Mullin, The bacteria in your gut may reveal your true age).
Article by Galkin et al. Human microbiome aging clocks based on deep learning and tandem of permutation feature importance and accumulated local effects is published on the bioRxiv – VM website.
Billions of bacteria that live in the intestine can participate in the regulation of many processes: from the ability to digest food to the functioning of the immune system. But scientists know very little about what a "normal" microbiome looks like and how it changes over time. The researchers studied the intestinal bacteria of thousands of people around the world and came to the conclusion that the state of the microbiome can be judged by the age of a person.
To find out how the microbiome changes over time, longevity researcher Alex Zhavoronkov and his colleagues from InSilico Medicine, an artificial intelligence startup in Rockville, Maryland, examined more than 3,600 samples of intestinal bacteria from 1,165 healthy people living around the world. About a third of the study participants were aged from 20 to 39 years, another third – from 40 to 59 years, the remaining – from 60 to 90 years.
The scientists then used artificial intelligence to analyze the data. First, they trained their computer program on 95 different types of bacteria from 90% of the samples, and also provided information about the age of the people from whom they were taken. The algorithm then had to predict the age of the people who provided the remaining 10% of the samples. The program was able to accurately determine the age within 4 years. Of the 95 bacterial species, 39 were the most important in predicting age.
Zhavoronkov and his colleagues found that some microbes became more numerous as people aged, such as Eubacterium hallii, which is believed to play an important role in intestinal metabolism. The number of others has decreased, like Bacteroides vulgatus, which is associated with ulcerative colitis – a type of inflammation in the digestive tract. Co–author Vadim Gladyshev, a biologist at Harvard University who studies aging, believes that changes in diet, sleep habits and physical activity probably contribute to these changes in different types of bacteria.
Zhavoronkov believes that the "microbiome aging clock" can be used as a basis for checking how quickly or slowly a person ages, and whether factors such as alcohol, antibiotics, probiotics and diet affect life expectancy. The new method can also be used to compare healthy people with those who have certain diseases, such as Alzheimer's disease, to see if their microbiomes deviate from the norm.
If this idea is confirmed, then microbiome analysis will join other biomarkers that scientists use to predict biological age, including the length of telomeres – the tips of chromosomes involved in aging – and changes in DNA expression during a person's lifetime. The combination of new aging clocks with already known ones can give a much more accurate picture of a person's true biological age and health. It may also help researchers to check more closely whether certain interventions, including medications and other treatments, affect the aging process. "You don't have to wait until people die to conduct experiments on longevity," says Zhavoronkov.
The idea that you can predict someone's age based on the gut microbiome is "very plausible" and "extremely interesting" for scientists studying aging, says computer scientist and microbiome researcher Robin Knight, director of the Center for Microbiome Innovation at the University of California, San Diego. His group analyzes 15,000 samples as part of the American Gut Project, a worldwide microbiome study that he launched to develop similar predictors of age.
But one of the problems of developing such watches is that there are huge differences in which bacteria are present in the intestines of people all over the world. "It's extremely important to replicate similar studies with markedly different populations" to find out if there are clear signs of aging in different groups of people, Knight believes.
He says that it is also not known whether changes in the microbiome are the cause of changes in the rate of aging of people, or whether these changes are only side effects of aging. InSilico Medicine builds several hours of aging based on machine learning that can be combined with microbiome. "Age is such an important parameter in all types of diseases," says Zhavoronkov. "We are changing every second."
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