1 Avenir Team Gut Microbiota and Immunity, UMR 7203, Saint-Antoine Hospital, Paris, France, INRA, UMR1319 Micalis & AgroParisTech, Jouy en Josas, France, and Department of Gastroenterology, Saint Antoine Hospital, AP-HP, UPMC Univ Paris 06, France; French Group of Faecal Microbiota Transplantation [GFTF] harry.sokol@aphp.fr.