Animal models of intestinal inflammation: new insights into the molecular pathogenesis and immunotherapy of inflammatory bowel disease

Inflammatory bowel diseases (IBDs) in humans are complex chronic inflammato ry disorders of largely unknown cause. Several mouse models that in some re spects resemble human IBDs have recently been developed and have provided n ew insights into immunoregulatory processes in the gut. Both genetic and en vironmental factors have been shown to be involved in chronic intestinal in flammation. In most of the models CD4(+) T lymphocytes have been identified as central mediators of inflammation. Inappropriate activation of T-H 1-do minated cytokine pathways upon contact with luminal bacterial antigens and lack of tolerance appear to be crucial for intestinal pathology. We present a brief overview of important animal models of IBD and describe the recent progress in understanding the mechanisms that contribute to chronic intest inal inflammation. Furthermore, novel immunotherapeutic approaches derived from such animal models are discussed.