1. Department of Microbiota Research, Juntendo University Graduate School of Medicine, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
2. Department of Gastroenterology and Hepatology, The Jikei University Kashiwa Hospital, 163-1 Kashiwashita, Kashiwa-shi, Chiba 277-0004, Japan