1. Center for Inflammatory Bowel Diseases, Division of Gastroenterology, Beth-Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
2. Rheumatology and Immunology Center, Research by AMC, READE and VUMC, Amsterdam, the Netherlands
3. Department of Dermatology, Ghent University, Ghent, Belgium
4. Department of Immunopathology, Sanquin Research and Landsteiner Laboratory Academic Medical Center, Amsterdam, the Netherlands