Previous studies have demonstrated that TNF‐driven intestinal inflammation in TNFΔARE mice (Kontoyiannis et al, 1999) is microbiota‐dependent, as TNFΔARE mice only develop spontaneous ileitis in colonized conditions, but not when raised under germ‐free (GF) conditions (Roulis et al, 2016; Schaubeck et al, 2016). Here, TNF is linked to Crohn ileitis.