27 July 2017

When good bacteria become Bad

Kirill Stasevich, "Science and Life", based on the materials of LiveScience: How 'Bad' Gut Bacteria Can Change Their Evil Ways

When it comes to the gastrointestinal microflora, they always talk about good bacteria and bad bacteria. The good ones help to maintain a healthy metabolism and not get fat, the bad ones – the proportion of which increases if you eat incorrectly – on the contrary, they spoil the metabolism, contribute to overweight and diabetes. 

But there are some gastrointestinal microbes that have long been considered harmful, and harmful in a special way - these are the bacteria of the Helicobacter group.


It is believed that gastritis begins because of them, stomach ulcers, duodenal ulcers, duodenitis, etc., develop because of them, up to cancer. At one time, a real war was opened in the USA against Helicobacter, massively ridding the population of these bacteria. (Indeed, no one disputes now that there is a definite connection between stomach cancer and one of the helicobacter pylori, Helicobacter pylori.) 

On the other hand, the more medical data accumulated, the more often it turned out that helicobacter in the digestive tract does not always provoke diseases, and that in general, the vast majority of Helicobacter carriers behave quietly and inconspicuously. 

Gradually, helicobacteria began to be treated as a kind of "two-faced" bacteria that behave differently depending on environmental conditions, and if conditions deteriorate – for example, a person is experiencing stress, or simply eats poorly – helicobacteria, as they say, break off the chain. However, for a long time it was not completely clear what exactly happens in this case from the point of view of cells and molecules. 

It can be assumed that it's all about immunity – more precisely, how helicobacter pylori communicate with the immune system. Indeed, as researchers from Washington University in St. Louis write in an article in Science Immunology, Helicobacter bacteria are able to act on the immune system in completely different ways.

In one case, Helicobacter pylori work the same way as other symbiont bacteria, acting as a sedative. Among the numerous cells of the immune system there are so-called T–regulatory lymphocytes, whose task is to suppress inflammatory signals, and good bacteria interact just with T-regulatory cells. Calm, adequate immunity is important not only for the bacteria themselves, but also for the body as a whole: if the T-regulators work poorly, then inflammation can begin without any reason at all, as an immune response to your own body tissues or to some food. In other words, symbiont bacteria help us to avoid allergies and autoimmune diseases in many ways

In a healthy intestine, helicobacter pylori, like other well-meaning microbes, act on T-regulators. But they can also act on T-effectors. Lymphocytes of this variety, on the contrary, enhance the immune response. And if, for example, colitis begins in the intestine – inflammation of the mucous membrane of the colon – then Helicobacter is activated by effector lymphocytes. As a result, the inflammation increases even more. (At the same time, other symbiont bacteria in colitis do not seek to strengthen the pathology at all.) In other words, the ambiguity of the behavior of helicobacteria is related to their ability to interact with different types of immune cells, stimulating completely different immune processes. While everything is fine, while the intestines are normal, Helicobacter maintain the norm, if something starts to go wrong, they only increase the irritation of the immune system. 

We repeat that we knew about the "duplicity" of helicobacteria before, but now it becomes more or less clear exactly how they enhance pathological processes. Knowing through which cells and through which cellular receptors Helicobacter acts, we can create drugs that would prohibit them from doing so, and thus we could suppress inflammation without bringing matters to more serious consequences. It probably doesn't make sense to exterminate helicobacter under the root – after all, they are even normally useful, as well as from ordinary microbial symbionts. 

Portal "Eternal youth" http://vechnayamolodost.ru  27.07.2017

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