Scientists from Brussels University noticed recently in a recent published article that enterotypes could be found also in mice model whatever the genetic background. Although genetic and environmental factor have to be taken in account during any experiment with mice, authors also said that mice enterotypes have also to be controlled. The two first authors of this study, Falk Hildebrand and Anh Nguyen from Raes group, accepted to explain us their interesting finding. Usually, scientist used mice models (wild or knock out strain) to study some effect but few is known actually on the global variation of mice gut microbiome regarding their genetic background and environmental laboratory factor (like cage effect).“We wanted to investigate the baseline gut microbiota composition of mouse strains commonly used in biomedical research.” Anh says, “We already knew that knock-outs of experimental mice showed variations in the gut microbiome from our previous work of our group, but if this was true for mice strains, although likely, was not clear to us.” Falk adds.

Authors were surprised that data showed a complete “chaos” regarding genetic background and the cage effect, indeed another confounding factor seemed to drive global variation of mice gut microbiome: enterotypes, defined as particular microbial community pattern found across gut microbiotas. “After we separated the data for enterotypes, the trends in the data got very strong and I concentrated on developing methods to take confounding factors into account” explains Falk says. However, showing that enterotypes exist in mice was probably the biggest challenge of their study,“we found 2 statistically significant clusters but it took quite some efforts to confirm those as enterotypes” says Anh and “there is enterotypes in the mouse gut, similar to those of humans!” adds Falk, this was the main findings of this study.

After segregating their data into enterotypes, authors showed that enterotypes are linked to naturally occur (low-grade) inflammation. Nevertheless, scientists said that number of genetic model tested here could be a limiting factor: “We wished to have included more mouse strains and have more mice for each strain sequenced. Also, further analysis of immune profiling of the mice in two enterotypes will provide much more details about the inflammation going on in the low-richness enterotype.”

Although this study was done in mice, the fact that enterotype is linked to inflammation grade is very important for the authors “Other studies have shown this general link between Bacteroides/Enterobacteria & inflammation, but the results were amazingly clear in our experiments, I was really surprised when I saw that!” says Falk.

To finish Anh explains “Enterotypes were reported in both humans and mice and this may be the universal signal across mammal kingdom. If such a link between enteroypes and inflammation also exists in human, it would suggest that some people, due to the nature of their (inflamed) enterotype, might be more prone to acquiring gastrointestinal diseases with an inflammatory component such as inflammatory bowel disease. It is also important to have a look at the patient’s enterotype before planning treatment since the background of gut microbiota in each person may be a different”.