An intestinal enterotype associated with both inflammatory bowel disease and depression

In 2012, Professor Jeroen Raes (Microbiology Center VIB-KU Leuven) launched the Flemish project Gut Flora. By sequencing fecal samples from more than 3,000 healthy volunteers, Professor Raes and his team defined the boundaries of a normal gut microbiota and associated health. The team then turned to the patient groups to identify the microbiome alterations associated with the diseases. Recently, they described the so-called B2 enterotype, deficient in some anti-inflammatory bacteria. Today, their results on the high prevalence of this particular enterotype in several diagnoses are published in Microbiology of nature.

Compare microbiomes

Inflammatory bowel disease (IBD) is a group of diseases characterized by chronic inflammation of the intestinal tract, including ulcerative colitis and Crohn's disease. Primary sclerosing cholangitis (PSC) is a chronic liver disease involving inflammation and scarring of the bile duct, often associated with IBD. In their new study, VIB-KU Leuven scientists describe the composition of the microbiome in patients with IBD and CSP.

Jeroen Raes, from VIB-KU Leuven, said: "Over the years, many research groups around the world have attempted to describe microbiota alterations associated with diseases." IBD is a hot topic in the world. research on the microbiome Our study differs from these previous attempts on three fronts We first compared the microbiota of patients with healthy volunteer profiles from our catalog of the Flemish project Gut Flora, composed of more than 3 000 microbiomes , then analyzed the percentages of different bacteria present in the stool samples, used a new technique to quantify their abundances, and third, we corrected our results for factors such as loose stools, often symptomatic in the diseases studied, but affecting the result of microbiome analyzes. "

A microbial imprint of the disease

By combining their unique expertise in quantitative microbiome profiling with their knowledge of microbiota variation associated with health, Leuven scientists identified a modified microbiome configuration, also called enterotype, with a high prevalence among patient groups. Although this enterotype was observed in 13% of healthy volunteers, it could be identified in 38 to 78% of patients with PSC or ITN.

The teacher. Séverine Vermeire, gastroenterologist at UZ Leuven / KU Leuven, who participated in the research, points out "This aberrant microbiome configuration, which we call B2 enterotype, is characterized by low abundance and biodiversity inflammatory bacteria such as Faecalibacterium In fact, we detect higher levels of intestinal inflammation in patients with enterotype B2, and even in healthy individuals, carriers of this enterotype exhibit slightly higher levels. high global inflammation of low grade. "

Inflammation, microbes and depression

Surprisingly, just a few months ago, Professor Raes's lab described a similar alteration of the microbiota associated with a lower quality of life and even depression.

Professor Jeroen Raes said: "There appears to be a large overlap of microbiome alterations observed among different patient groups.We have detected enterotype B2 in about 26% of depressed people.It has been shown that intestinal microbiota plays a role in the development of the disease Ulcerative colitis and Crohn's disease, for example, are much less clear with regard to depression, however, we will study in more detail the link between B2 enterotype and depression in the next studies. "

While nearly 13% of healthy people can be classified as carriers of the B2 enterotype, the researchers point out that this should not be a cause for concern.

Jeroen Raes: "At this stage, we can not predict susceptibility to disease or risk based on a person's enterotype." In addition, enterotypes are not fixed and can be modified by The associations observed between diseases and microbiota constellations do not imply that the intestinal bacterium is at the origin of the disease.Many personal factors, related to the way of life and Environmental factors are related to a B2 enterotype, however, as inflammation also appears to be a factor associated with B2, we will most certainly look more at potential causality. "