During his medical thesis and a subsequent postdoctoral fellowship at the Charité Berlin his research focused on Crohn’s disease, an inflammatory disease of the intestine, which often manifests during adolescence and follows a chronic course. He investigated the role of the intestinal epithelium, an interface and barrier between the human tissue and the microbial flora of the intestine, and could demonstrate how dysfunction of the intestinal epithelial barrier contributes to disease pathogenesis and how it can be restored upon neutralization of a single inflammatory mediator (TNFalpha).

During a subsequent postdoctoral fellowship at the Harvard Medical School in Boston he investigated the immunological aspects of intestinal diseases. Thereby, he could demonstrate that a rare metabolic disorder called abetalipoproteinemia is associated with severe immunological defects thus reflecting a primary immunodeficiency rather than a sole metabolic disorder.  These results are not only of scientific interest, but are likely to have a significant impact on future treatment decisions of patients with abetalipoproteinemia.

In a further project, he investigated the mechanisms of the immune defence against Hepatitis B virus and could demonstrate, for the first time, that lipid-reactive immune cells play a critical role in the control of viral infection.  These findings have led to the redefinition of the mechanisms of immune-mediated defence in Hepatitis B virus infection and have provided new insight into potential future treatment option for chronic hepatitis.

After his postdoctoral fellowship in Boston, he continued his scientific and clinical career as research group leader in the Department of Internal Medicine I at the University Medical Center Schleswig-Holstein in Kiel. In 2012, he was appointed Junior Professor for Immunological Aspects of Intestinal Barrier Diseases at the University of Kiel.