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My research focuses on the interaction between diet, gut microbiota and mucosal barrier function.
The intestine is one of the most densely populated habitats on our planet. Trillions of microorganisms, mainly bacteria, live in our gut in a relationship from which both sides benefit: The host provides continuous supply of nutrients and a constantly warm temperature, while the bacteria produce vitamins and other factors that are beneficial for the host. However, the high density of the gut bacteria is a permanent threat to the body and efficient defence mechanisms are required to protect the body against infection by this intestinal bacterial community. Therefore, the body has developed various mechanisms of border protection. First, a dense and sticky layer of mucus covers the intestinal surface and thereby physically hinders bacteria from invading into the body. In addition, mucus is filled with so called antimicrobial peptides, which are antibiotics produced by the body to kill bacteria that manage to penetrate into the mucus barrier.
In previous experiments we showed that mice that were fed a “Western-style diet” – a diet similar to fast food that contains high amounts of simple sugars and fat but lacks dietary fibre – had a different composition of gut bacteria, which caused damages in the mucus shield. Consequently, bacteria could come closer to the epithelium, which increases the risk for infections and inflammation in the gut. Of note, we found that application of a probiotic Bifidobacterium or the prebiotic dietary fibre inulin, which is, for example, present in chicory and Jerusalem artichokes, was protective for intestinal barrier function. Thus, bacteria and diet can both affect mucus function, but the details are yet to be determined.
In my laboratory we thus plan to investigate the interaction between diet, gut bacteria and intestinal barrier in more detail. We will feed diets with different kinds and amounts of dietary fibre to mice and investigate the effect on intestinal barrier function. As a second mechanism of intestinal barrier function, we will analyse the amount and function of antimicrobial peptides in the gut of mice fed the different diets. By combining these experiments with parallel analysis of their gut bacteria composition, this approach allows us to link specific gut bacteria to a functional or dysfunctional barrier.
My motivation behind this project is my wish to contribute to a better understanding of how modern dietary habits affect intestinal defence mechanisms. In the industrialized world, diseases such as inflammatory bowel disease and metabolic disease are on the rise and have been linked to the gut microbial community and intestinal barrier defects. As diet is one of the most important factors that shapes the community in the gut, I hope to clarify the involvement of specific food components in the complex regulation of gut barrier function.
Schröder lab: www.mucubacter.org
Laboratory for Molecular Infecion Medicine Sweden (MIMS): www.mims.umu.se/groups/bjorn-schroder