1. Departments of Internal Medicine and Immunology, Erasmus MC University Medical Center Rotterdam, Rotterdam, the Netherlands
2. Leiden University Medical Center, Leiden, the Netherlands
3. Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center Rotterdam, Rotterdam, the Netherlands
4. Department of Pathology, Erasmus MC University Medical Center Rotterdam, Rotterdam, the Netherlands
5. Department of Otorhinolaryngology, Franciscus Gasthuis & Vlietland, Rotterdam, the Netherlands
6. Department of Otorhinolaryngology and Head and Neck Surgery, Erasmus MC University Medical Center Rotterdam, Rotterdam, the Netherlands