[1] Univ Leeds, St Jamess Univ Hosp, Leeds Inst Biomed & Clin Sci, Leeds, W Yorkshire, England
[2] Univ Manchester, Ctr Gastrointestinal Sci, Manchester, Lancs, England
[3] Mayo Clin, Gastroenterol & Hepatol, Jacksonville, FL 32224 USA
[4] Univ Manchester, Univ Hosp South Manchester, Sch Biol Sci, Div Infect Immun & Resp Med, Manchester, Lancs, England