Useful Bacteria This is how the stomach helps the intestines to jump

Filter function discovered: stomach specifically enriches microorganisms

In the past, science assumed that gastric acid kills almost all microorganisms. But that is obviously not the case. Because in a study has now shown that the stomach micro-organisms targeted and depleted and filtered to the intestine releases.

Composition of microorganisms in the stomach varies greatly

The role of the stomach for the health of the gastrointestinal tract is still a mystery to science: The composition of the microorganisms in the stomach varies greatly, but the influence of these fluctuations on the intestine has so far only been speculated. But now a research team at the University of Hohenheim in Stuttgart, in collaboration with the Medical University of Graz, has developed a method by which living, active bacteria can be distinguished from dead and their quantity determined.

A new study has shown that the stomach within the gastrointestinal tract exerts an important control function on the passage of certain bacteria into the intestine. (Image: Alexander Raths / fotolia.com)

Important control function

With this method, it was possible for the first time to associate variations in the composition of the permanent inhabitants of the stomach with an overall increase in bacteria.

As stated in a communication from the University of Hohenheim, it also became clear that the stomach within the gastrointestinal tract has an important control function on the passage of certain bacteria into the intestine.

The current results have now been published in "mSystems", the journal of the "American Society for Microbiology".

Influence of the stomach on the intestine

A surgical stomach reduction in obesity (obesity) brings with it positive features that can not be explained by a reduction in gastric volume alone.

For example, insulin resistance may decrease and improve the associated regulation of blood sugar levels as well as general inflammatory parameters - an effect that is typically associated more with processes in the intestine than in the stomach.

Similar questions on the influence of the stomach on the intestine raise clinical observations on the side effect of proton pump inhibitors.

These are drugs that inhibit acid production in the stomach and are among the most commonly prescribed drugs to treat stomach ulcers, heartburn, etc..

But those who take them for a long time have an increased risk of getting diarrhea after taking antibiotics.

"Both are indications that events in the stomach cause changes in the intestinal microbiome," explains Prof. Dr. med. Florian Fricke, Head of the Department of Microbiome and Applied Bioinformatics at the University of Hohenheim.

"The stomach may be more influential in gut related problems than previously thought - both positive and negative."

Previous assumption does not seem right

Earlier, according to Prof. dr. Fricke assumed that gastric acid kills almost all microorganisms.

"That's obviously not the case. But what a healthy stomach microbiome looks like and what influence it exerts on the transfer of microorganisms from the mouth to the intestine, we did not know, "says the expert.

"Previous studies of the stomach as well as the intestine were also hampered by the extremely fluctuating levels of various bacterial species in the microbiome. So far, there was no explanation for healthy persons, "said Prof. Dr. med. Fricke.

New method distinguishes living and dead bacteria

The problem of classical microbiome research is that the so-called sequence-dependent methods exclusively examine DNA, ie the relatively stable molecular carrier of the genetic information of a bacterium.

"They capture living bacteria as well as dead cells - so they can not distinguish between the microbiome adapted to the stomach and the inactive bacteria that enter from the outside."

Together with his doctoral student Elisabeth Dörner and his colleagues at the Medical University of Graz, Prof. Dr. med. Therefore, Fricke takes a new technical approach - and uses a trick:

They capture not only the DNA, but also the RNA - short strands of nucleic acid that act as a messenger in the living cell when using the genetic information and are therefore found only in living, active cells.

The scientists test the method in the animal model on stomach samples from laboratory mice. At the same time, the project partners in Graz take samples from a total of 24 patients, who send them to Hohenheim for analysis.

Researchers isolate DNA and RNA separately from each sample and characterize both using PCR analysis, a method for enrichment and sequencing of genetic material.

"This determines which bacteria are present in total and which parts of the total bacteria are active", explains Prof. Dr. med. Fricke.

"In addition, we can also use this method to determine the quantity of bacteria. Therefore, we can not only determine the relative percentages of each species, but also their absolute quantities. "

Much of the stomach bacteria of only two groups

The researchers found that around 90 percent of gastric bacteria in mice and humans are made up of only two dominant groups.

One of these groups, the lactobacilli in mice and human streptococci, is relatively constant in volume while the other group of bacteroidetes is more variable.

"It is interesting that the constant group also makes up the active, living bacteria", emphasizes Prof. Dr. med. Fricke.

"One can conclude that it has more critical functions for the gastric microbiome, while the short-term fluctuating group may enter the stomach through food or other pathways, but remain inactive there," said the scientist.

"With our results, we can narrow the focus to the bacteria relevant to the study of the stomach and the transition to the gut."

Stomach can affect intestinal microbiome

To better understand the functions of the stomach, the researchers do not confine their sampling to the stomach, but also take a sample from the esophagus, three at different sites of the stomach and one from the duodenum.

"Although the microbiome is relatively similar everywhere, there are gradual differences," explains Prof. Dr. med. Fricke.

"We have found gradients in certain bacteria, ie increases or reductions from the esophagus to the stomach, which afterwards, ie between stomach and small intestine, are in opposite directions," says the expert.

"In the stomach, these bacteria are thus specifically enriched or depleted. He thus seems to exert a control or filter function as a portal to the intestine and can thus influence the intestinal microbiome. "

Detecting risks to the gut in saliva

At present, scientists are still conducting classical basic research.

"We hope that our findings will help to better understand the relationships between the different parts of the gastrointestinal tract and, one day, to associate deviations in the microbiome of the stomach or oral cavity with certain diseases of the intestine," says Prof. Dr. med. Fricke.

"It would be conceivable, for example, that someday one could recognize and treat risks to the intestine in saliva. Or that one can compensate for the negative effects of drugs such as acid inhibitors in the stomach by simultaneously influencing the microbiome. "(Ad)