Interfakultäres Institut für Mikrobiologie und Infektionsmedizin

Current Projects of the Reserach Group of Julia Frick

Impact of the intestinal microbiota on induction of regulatory B cells

Jan Kevin Maerz, PhD Student

In general, B cells positively regulate adaptive immune responses by the production of antibodies and thus facilitate optimal CD4+ T-cell activation. Additionally, B cells modulate the innate immune system via presentation of antigens and the secretion of immune-modulating cytokines. Furthermore, a specific subset of B cells (Bregs) exhibit immunosuppressive functions and can also negatively regulate the immune response in mouse models of autoimmune diseases. Thereby the intestinal microbiota plays a critical role for the induction of different B cell phenotypes either by direct or indirect interaction.

In order to clarify the influence of the intestinal microbiota composition on B cell-mediated immune responses and the role of Bregs in supporting immune homoeostasis, we focus on the immune system activating capacities of two completely sequenced bacterial strains in vitro and in vivo.

 

Work on strategies of symbiotic and pathobiontic commensals to colonize the gut and how they survive in the healthy and inflamed intestine.

Dr. rer. nat. Anna Lange

Pathobionts like E. coli colonize the gut in very low amounts and symbiotic commensals in high abundance the must use different metabolic pathways to grow and reside in the gut ecosystem. Based on genome sequencing certain pathways are investigated.

 

Immunomodulatory properties of E. coli Nissle flagella

Thomas Hagemann, PhD student and Lena Michaelis, PhD Student

E. coli Nissle is a probiotic bacterial strain which is known to promote intestinal homeostasis. As many other bacteria, this strain contains a flagellum, making it a motile bacterium. The flagellum is built up of the FliC protein and we are interested how the E. coli Nissle flagella in general, and FliC in specific, help to promote E.coli Nissle mediated intestinal homeostasis. Answering this question might allow to elucidate future therapeutic approaches using isolated FliC protein in patients with Inflammatory Bowel Diseases.

 

Commensal bacterial surface structures as potential immunomodulatory agents?

Jan Kevin Maerz, PhD student

Not only the bacterial flagellin, but also other bacterial surface compounds are potent immunomodulatory agents. We therefore screen for other structures, derived from certain commensals which might be able to restore intestinal homeostasis and/or promote healing of damaged colonic tissue, like it is observed in Inflammatory Bowel Disease Patients.

 

Commensals and their impact on Th17 immune responses

Lena Michaelis, PhD student

Th17 immune responses are known to contribute to the progress auf autoimmune diseases. We therefore have a closer look, how distinct commensal bacteria differentially promote or prevent Th17 responses on the host, on a systemic and molecular level.

 

Immune signaling during infection in a novel animal model: Galleria melonella

Raphael Parusel, PhD student

The invertebrate greater waxmoth Galleria mellonella represents a novel animal model in infection biology. According to the 3R strategy (reduction, replacement, refinement) we want to promote Galleria mellonella as a potential invertebrate alternative to mice by establishing defined molecular read-outs. Since to date less is known about Galleria mellonella immune defense mechanisms and detailed signaling pathways, we focus on basic research on these issues.

 

Establishment of Galleria mellonella as a host model to study gut microbe interactions and the maintenance of gut homeostasis.

Dr. rer. nat. Anna Lange

Due to strict regulations concerning animal grants and for ethical reasons we seek to establish an substitute invertebrate host model, which can be used to analyze the effect of certain microbes both commensals and pathogens on the innate immune system of Galleria mellonella. As the innate immune system is highly conversed among mammals and insects such substitute models can be used prior to experiments with mammals.