Junior Research Group Microbiota–Host–Interaction

Head: Dr. Gunnar Loh

The Junior Research Group Microbiota–Host–Interaction, established in 2006, investigates the impact of intestinal bacteria on chronic gut inflammation. We also aim to identify host-specific factors responsible for development of individual intestinal microbiota composition.

Projects

Host-specific microbiota
Frances Brodziak

We hypothesized that the Toll-like receptors (TLR) 2 and 4 influence gut microbiota composition. These receptors recognize components of Gram-positive or -negative bacteria and the innate immune system may respond by excluding these bacteria from the gut. After association of germ-free TLR2/4 double knockout and respective wild-type mice with intestinal microbiota of a conventional mouse, the microbiota composition of the animals did not differ. In contrast, ex-germ-free mice from various inbred strains differed in bacterial colonization after association with identical microbiota, indicating that genetic factors other than TLR2/4 may govern bacterial colonization of the gut. To identify such factors, we are examining gene and protein expression in gut epithelium of mice with different bacterial colonization patterns.

Chronic gut inflammation
Steffen Wohlgemuth

Impaired host-microbe interactions contribute to onset of chronic colitis but underlying mechanisms have not yet been elucidated. In a mouse model for chronic colitis we observed a reduced gut microbiota diversity accompanied by much higher Eschericha coli cell numbers in the inflammed gut (Fig. 1). We identified one single E. coli strain representing the total E. coli population with a high number of virulence genes in its genome. This strain is highly adapted to the murine intestine. We are exploring the impact of the virulence genes on gut colonization and inflammation.