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uni'wissen 02-2012 ENG

Prof. Dr. Andreas Diefenbach studied medi- cine in Erlangen, where he earned his PhD at the Institute of Clinical Microbi- ology and Immunology. He then conducted research in the USA, first at the Uni- versity of California, Berke- ley, at the Department of Molecular and Cell Biology. Starting in 2003 Diefen- bach worked at the New York University Medical Center as an assistant professor in the fields of immunology and pathol- ogy. In 2005 he returned to Germany and accepted a chair in Freiburg. He serves as deputy director of the Institute of Medical Microbiology and Hygiene of the Freiburg University Medical Center and heads a research group devoted to inborn immunity and the immunology of biologi- cal boundary layers like the intestinal epithelium and skin. Further Reading Kiss, E. A./Vonarbourg, C./Kopfmann, S./Ho- beika, E./Finke, D./Esser, C./Diefenbach, A. (2011): Natural aryl hydrocarbon receptor ligands control organogenesis of intestinal lymphoid follicles. In: Science 334, p. 1561–1565. Kiss, E. A./Diefenbach, A. (2012): Role of the aryl hydrocarbon receptor in controlling main- tenance and functional programs of RORγt+ innate lymphoid cells and intraepithelial lym- phocytes. In: Frontiers in Immunology 3, p.124. “Since we are working on the digestive tract, nutrients struck us as the most interesting candidates” Elina Kiss studied biology with an emphasis on biochemistry in Turku, Finland, and has conducted research at the Spemann Graduate School of Biology and Medicine (SGBM) of the University of Freiburg since 2008. For her work on the devel- opment and function of particular immune cells in the intestines, the LTi cells, she received the Barbara- Hobom Prize in 2011. The prize is awarded each year to promising young scien- tists by the Freiburg Clus- ter of Excellence BIOSS Centre for Biological Sig- nalling Studies. She is almost finished with her doctoral dissertation. Afterwards, Elina Kiss plans to continue her work in the research group of Prof. Dr. Diefenbach. search. She can be proud of her work: Her findings were published in the renowned journal Science, and she also received the 10,000 euro Barbara Hobom Prize for her research. Andreas Diefenbach is also satisfied with the results: “We found the molecular connection of the AhR and nutrients to the LTi cells and folli- cles.” Stated in the simplest of terms: Broccoli plus AhR equals more LTi cells and follicles that produce IL-22, which in turn enables the intesti- nal epithelium to produce antimicrobial proteins. The aryl hydrocarbon receptor presumably also strengthens the barrier function of the intestinal epithelium. It lowers the risk of infections by sealing off this barrier layer and preventing germs from the intestines from entering. In addi- tion, the LTi cells probably regulate the stem cells of the intestinal epithelium. Like the LTi fol- licles, they are located in the crypts. From there they control the regeneration of the layer, which renews itself completely every two days. Gluco- sinolates could potentially even improve the re- generation over the AhR. This would make it possible to keep centers of inflammation at bay in the case of chronic-inflammatory intestinal diseases like Crohn’s disease. Sautéing Is Better Than Cooking That is one of Diefenbach’s long-term goals: “After all, we are also doctors and want patients to profit from our research.” However, several questions are still awaiting an answer: What sig- nals influence the epithelial cells? How much broccoli or Brussels sprouts is enough? “We used amounts that correspond to those that hu- mans take in with food,” says the scientist. But do humans react to broccoli in exactly the same way as mice? What amount could lead to unde- sired effects, and what amount are people willing to eat? Andreas Diefenbach does not yet have answers to these questions, but he does have a tip: It is better to sauté vegetables from the cab- bage family for a short time than to cook them in water for a long time. This way they don’t lose many of the precious glucosinolates. 27