For participant, 4 to 5 ileal biopsies will be taken during a routine colonoscopy. Patients will be classed in three groups according to their number of CARD15/NOD2 mutations (1) wild-type, 2) mutated heterozygotes and 3) mutated homozygotes or compound heterozygotes). A comparison between groups and with non inflammatory (colonoscopy performed for other reasons) or inflammatory (ulcerative colitis patients) controls will be done. For each group, cell phenotype, cytokine profile, permeability and bacterial translocation will be analysed on Peyer's patches.