Bowel bacteria reprogram mucosal genetic activity

Another way in which microbes in the intestines affect the human body has been discovered by the research group of the German Cancer Research Center (DKFZ) and the Hebrew University of Jerusalem.
Comparing the DNA of the cells in the intestinal mucosa of two groups of mice, one with a normal microbiome and the other made up of mice grown under sterile conditions, the researchers found that the same microbes in the intestine can reprogram genetic activity by controlling the development of intestinal inflammation.

In essence, intestinal bacteria can reprogram DNA activity in mucosal cells, something that can have a big impact on the health of the intestine itself.
In order to confirm this, the researchers carried out experiments on mice, dividing them into two groups, one with mice with a normal intestinal microbiome, i.e. the intestine normally colonized by bacteria, and another with mice that grew in sterile conditions, and therefore with much fewer bacteria in the intestine.

The mice were then treated with a chemical that attacks the intestinal mucosa, which produces acute inflammation.
In mice with a normal microbiome, the treatment led to a decrease in DNA methylation in the cells of the intestinal mucosa.

As a result, several genes were activated that play an important role in inflammation and cancer. In the other group, however, the chemical did not cause many changes in genetic activity, which shows that the differences in methylation were caused by bacteria and not by the chemical directly, as Frank Lyko, who conducted the research together with Yehudit Bergman, explains.

“The microbiome seems to have a significant influence on animal health: it ensures normal intestinal development by using epigenetic programming to activate the genes that guide the regeneration of the intestinal mucosa. In mice without microbes, however, this activation does not take place,” explains Lyko again, implying the important role of intestinal bacteria in epigenetic regulation.

“We have shown that exposure to microbiota in acute dextrans-induced sodium sulfate inflammation causes deep DNA methylation and changes in the accessibility of chromatin to regulatory elements, leading to alterations in gene expression programs enriched with functions associated with colitis and colon cancer,” the researchers report again in the study abstract where it is clearly reported that epigenetic changes caused by microbes in the gut are essential for proper homeostasis in vivo.