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A single gut enterotype linked to both inflammatory bowel disease and depression

Leuven scientists identified an altered microbiome configuration—also known as an enterotype—with high prevalence among patient groups.

In 2012, Professor Jeroen Raes (VIB-KU Leuven Center for Microbiology) launched the Flemish Gut Flora Project. Sequencing fecal samples of over 3,000 healthy volunteers, Prof. Raes and his team defined the boundaries of a normal, health-associated gut microbiota.

Next, the team turned to patient groups to identify microbiome alterations associated with diseases. Recently, they described the so-called B2 enterotype, deficient in some anti-inflammatory bacteria.

Inflammatory bowel disease (IBD) groups several conditions characterized by  of the intestinal tract, including ulcerative colitis and Crohn’s disease. Primary sclerosing cholangitis (PSC) is a chronic liver condition involving inflammation and scarring of the bile duct, often concomitant with IBD.

In their new study, the VIB-KU Leuven scientists describe microbiome composition in patients suffering from IBD and PSC.

Combining their unique expertise in quantitative microbiome profiling with their knowledge on health-associated microbiota variation, the Leuven scientists identified an altered microbiome configuration—also known as an enterotype—with high prevalence among patient groups.

While this enterotype was observed in 13% of , it could be identified in 38 to 78% of PSC and IBD patients.

Prof. Séverine Vermeire, gastroenterologist at UZ Leuven/KU Leuven, who participated in the research, clarifies “This aberrant microbiome configuration, which we call the B2 enterotype, is characterized by low bacterial abundances and biodiversity. It is notably deficient in some anti-inflammatory bacteria such as Faecalibacterium. In fact, we detect higher levels of intestinal inflammation in patients with the B2 enterotype. Even among healthy individuals, carriers of this enterotype have slightly higher levels of overall low-grade inflammation.”

Surprisingly, only a few months ago, the lab of Prof. Raes described a similar microbiota alteration to be associated with lower quality of life and even depression.

Prof. Jeroen Raes says “There appears to be a large overlap in alterations observed across different patient groups. We detected the B2 enterotype in around 26% of depressed individuals. While the  has been shown to play a role in disease development in, for example, ulcerative colitis and Crohn’s disease, this is far less clear for depression. However, we will explore the association between the B2 enterotype and depression in more detail in future studies.”

While around 13% of healthy individuals can be classified as carriers of the B2 enterotype, the researchers stress that this should not be a reason for concern.

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Posted on: June 18 2019

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