Is dysbiosis the cause of aging?
Biologists have found bacteria in the intestines that accelerate aging
Experiments on flies helped Swiss biologists to discover extremely unusual representatives of the microflora that directly affect the work of the immune system and accelerate the aging of the body. Their findings were presented in the journal Immunity (Iatsenko et al., Microbiota-Derived Lactate Activates Production of Reactive Oxygen Species by the Intestinal NADPH Oxidase Nox and Shortens Drosophila Lifespan).
"We have discovered a specific microbe and the product of its vital activity that affects the rate of aging of the host organism. There is no doubt that there are other examples of similar bacteria, which indicates the need to study how the microflora affects aging and how this process can be controlled," says Igor Yatsenko from the Federal Polytechnic School in Lausanne (in a press release Immunity connects gut bacteria and aging – VM).
The human body contains about 10 times more unicellular bacteria, fungi and other representatives of the microflora than our own cells. Observations of recent years show that microflora can not only affect a person's metabolism and the likelihood of developing cancer and other diseases, but also his behavior.
For example, a year ago, American biologists discovered, experimenting on mice, that the development of autism may be due to the absence of one type of microbes, Lactobasillus reuteri bacteria in the intestines of children and their mothers.
In addition, Russian biologists have repeatedly suggested that microflora can influence more complex behavioral reactions, affecting the level of hormones and signaling molecules of the nervous system. Relatively recently, scientists have found hints that the features of the device and the work of the brain in women may be related to the structure of their microflora.
Yatsenko and his colleagues found out that the composition of the microflora can strongly influence the aging of the human body and other animals by studying how the "friend-foe" system works, protecting intestinal bacteria from the attention of the immune system.
To do this, scientists damaged the PGRP-SD gene, responsible for recognizing "their" bacteria, in the DNA of several fruit flies, which deprived them of the ability to recognize useful and dangerous microbes.
Such a modification of the genome led to an unexpected consequence – the average life expectancy of insects has sharply decreased. Trying to understand what this is due to, scientists compared the species composition of the microflora of these fruit flies and their normal relatives, and found a possible "culprit" – the bacterium Lactobacillus plantarum.
As it turned out, the destruction of the "friend-foe" system led to the uncontrolled reproduction of this microbe in the intestines of flies, where a small number of these bacilli are usually present. As a result, a large amount of lactic acid began to enter the body of drosophila, which caused inflammation and provoked the formation of molecules of various oxidants.
Oxidants, in turn, began to destroy the DNA of intestinal cells and cause their mass death. This accelerated the aging of the flies and led to their relatively early death. As scientists suggest, similar processes can occur in the intestines of humans and other mammals.
If this is the case, then such a connection may explain why many people inexplicably age much faster than their peers and relatives who lead a similar lifestyle.
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