PGLYRP1 and colitis: Reciprocally, the shaping of microbiota composition by the immune system has been demonstrated in several mouse models, among them NOD2-deficient mice, PGRP- (peptidoglycan recognition protein-) deficient mice, and TRUC mice, in which immune defects induce the establishment of a colitogenic flora able to transfer colitis to healthy mice [146–148].