1. Division of Gastroenterology, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
2. Department of Microbiology and Immunology, Institute for Immunology and Immunological Diseases and Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, Korea
3. Department of Internal Medicine and Institute of Gastroenterology, Yonsei Cancer Prevention Center, Brain Korea 21 PLUS Project for Medical Sciences Yonsei University College of Medicine, Seoul, Korea