The study of the gut microbiome by Japanese and American scientists provides one of the potential keys to longevity and the treatment of bacterial infections.
Long-livers - according to the classic definition, those who have passed the threshold of 90 years - throughout their existence are less susceptible to age-related chronic diseases and are more likely to safely tolerate diseases. A new study by scientists from Keio University School of Medicine (Japan), Broad Institute at Massachusetts Institute of Technology and Harvard (USA) has shown that people who live to 100 years of age and older have a unique microbiome, which, apparently, protects them from certain bacteria. including drug resistant. The results of the work were published in the journal Nature.
The microbiome is made up of trillions of microorganisms, also called microbiota or microbes, of thousands of different species. These include not only bacteria, but also fungi, parasites and viruses. In the body of a healthy person, they all peacefully coexist, and the largest amount is contained in the small and large intestines. The microbiome is essential for the body to function smoothly and daily.
Each person has a unique microbiota, which is initially determined by their DNA. For the first time, we are exposed to microorganisms during natural birth and breastfeeding. What kind of living organisms a child encounters depends solely on the mother's microbiome. Later, the environment and diet are influenced.
Most of the microbes in the body are symbiotic, and some, in smaller numbers, are pathogenic, that is, they contribute to disease. In a healthy body, pathogenic and symbiotic microbiota coexist without problems, but if the balance is disturbed due to infections, diet or antibiotics and other drugs that destroy bacteria, dysbiosis occurs. As a result, a person is more susceptible to disease.
A new study by Japanese and American scientists reveals the secret to long-livers and provides new data on what gut microflora means to our ability to fight disease. They studied microbes found in fecal samples from more than 300 Japanese residents, whose average age was 107 years. As it turned out, compared with the control groups (they included people 85-89 years old and 21-55 years old), centenarians have higher levels of several types of bacteria - producers of secondary bile acids (deoxycholic and lithocholic, formed by dehydroxylation at C-7 of primary acids in the gastrointestinal tract). These molecules are thought to protect the intestines from pathogens and regulate the body's immune responses.
When the authors studied 68 bacteria from the microbiome of a 100-year-old person, about eight were able to produce the antimicrobial chemical under the right conditions. Then they conducted an experiment in the laboratory: they acted on the common bacteria that cause infections with secondary bile acids. The researchers focused on isoallo-lithocholic acid (isoalloLCA) inhibited the spread of Clostridioides difficile, a species of anaerobic spore-forming gram-positive bacteria from the Peptostreptococcaceae family of the Clostridia class. It is the main causative agent of pseudomembranous colitis, which occurs when the intestinal microflora is destroyed by antibiotics. After C. difficile-infected mice were fed a diet supplemented with isoalloLCA, the infection was suppressed.The acid also effectively inhibited the growth of many other gram-positive pathogens and killed them. Therefore, scientists hypothesized that isoalloLCA helps the body maintain a healthy gut microbiota balance.
“A unique cohort, international collaboration, computational analysis, and experimental microbiology have all revealed that the gut microbiome is the key to healthy aging,” they said. "Our collaborative work has shown that future research on microbial enzymes and metabolites can help define starting points for treatment."
Now the authors of the work plan to understand how to act on bile acids in order to treat infections caused by antibiotic-resistant bacteria. Of course, the study had one limitation: you can't find out if the young people who participated in the experiment can become centenarians themselves, plus the results should be double-checked not only in Japanese. In addition, scientists assessed only one aspect of aging, but not, for example, the increased risk of cancer and cardiovascular disease.