Animal models of IBD: linkage to human disease.

Spontaneous development of intestinal inflammation in many different kinds of genetically engineered mice as well as the presence of numerous susceptibility genes in humans suggests that inflammatory bowel disease (IBD) is mediated by more complicated mechanisms than previously predicted. The human genetic studies implicate some major pathways in the pathogenesis of IBD, including epithelial defense against commensal microbiota, the IL-23/Th17 axis, and immune regulation. Murine IBD models, which are genetically engineered to lack some susceptibility genes, have been generated, and have provided useful insights into the therapeutic potential of targeting the susceptibility genes directly or their downstream pathways indirectly for IBD. This review summarizes current information related to the function of IBD-associated genes as derived from genetically engineered mouse models.