Key bacteria discovered – protect the intestinal mucus barrier in case of a low-fiber diet

Our findings contribute to a greater understanding of how the intestinal flora and mucus layer work and may ultimately lead to new treatment strategies for diseases associated with the Western diet such as inflammatory bowel disease and ulcerative colitis, says Sandra Holmberg, a doctoral student at Harvard Medical School. Department of Molecular Biology at Umeå University.

To protect itself from the trillions of microorganisms in our gut, our body needs effective defense mechanisms. One of the main means of protection is the mucous layer that covers the intestines. This mucus is closest to the body's intestinal cells, and is impervious to bacteria and thus maintains a healthy distance from the intestinal flora. In the large intestine, where the amount of intestinal flora is greater, this barrier is maintained by mucus that is constantly secreted from the body.

Diet affects the intestinal flora and mucosal barrier. Previous studies have shown that if mice are given, for example, a Western diet low in fiber and high in fat and sugar, the composition of the intestinal flora changes, and the mucus layer shows increased bacterial permeability and decreased secretion. This may lead to inflammation because the intestinal flora gets closer to the body, but it was not clear what components of intestinal flora in particular are and what are the mechanisms by which mucus is regulated.

In collaboration with researchers in Germany and Finland, research leader Björn Schröder and his group investigated this specifically by following people who changed their diet and then using mouse models to study the effect of intestinal flora on mucus function.

In the three-month study, healthy participants increased their daily intake of dietary fiber by 10 grams, which is equivalent to about four apples or 3 dl of oatmeal. In order to examine the importance of increasing fiber intake, intestinal flora was collected at the beginning and end of the study. They were then transplanted into mice fed a low-fiber Western diet. In the group of animals transplanted with intestinal flora from the beginning of the study, mucosal damage could be demonstrated, while the opposite was seen in the group with increased dietary fiber consumption.

– The results indicate the important role that dietary fiber plays in the intestinal flora, which in turn contributes to maintaining the important mucosal barrier, says Rachel Finney, a doctoral student in the Department of Molecular Biology at Umeå University.

The researchers studied the bacterial composition of the intestinal flora and observed bacterial growth, among other things Plutia After a period of increasing fiber intake. Its presence is also linked to mucus function measured in mice. Through murine supplementation studies where only plutia was supplemented with the Western diet, similar improvements could be observed, as previously seen when transplanting highly fibrous human flora, in mucus function.

Using specialized mucus measurement technology, the researchers discovered that even Plutia secreted molecules can directly stimulate mucus secretion, demonstrating how their presence can maintain mucus function in a low-fiber environment. Researchers found short-chain fatty acids when they identified the molecules they secrete Plutia – Structures that have previously been shown to be beneficial for gut health. Surprisingly, these molecules were able to directly improve mucus function, which describes the mechanism behind the bacteria's function

addition Plutia It also reduced the infection pressure of enteric pathogens similar to human pathogenic bacteria coli bacteria.

– So we conclude that Plutia It also has potential protective effects in the event of infection, says Vishnu Prasudhanan, a postdoctoral fellow in the Department of Molecular Biology at Umeå University.