Longitudinal modifications of histological severity of duodenal damage in CD patients following GFD. a IEL: at baseline, 52% of CD patients presented with IEL >80/100 Epithelial cells (Ep.); 45% with IEL between 50 and 79/100 Ep. and the remaining 3% with IEL between 25 and 49/100 Ep. Upon GFD commencement, IEL progressively decreased. b Histological severity of duodenal damage evaluated according to the Marsh classification modified by Oberhuber (Marsh): at baseline, 58% of patients presented with a Marsh IIIc; 29% with Marsh IIIb and the remaining 13% with Marsh IIIa. Upon GFD commencement, all patients experienced a progressive villous regeneration. c and d depict representative CD patients’ endoscopic pictures (water immersion technique), while panels e and f correspond to their histological appearance (H&E staining). T0 baseline, T1m, T6m, T12m and T24m 1, 6, 12 and 24 months following gluten removal from diet, respectively.