1. NIHR Nottingham Biomedical Research Centre, Department of Gastroenterology, Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK
2. Department of Gastroenterology, Hospital Universitario Central de Asturias, Oviedo, Spain
3. Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain