Monday September 24, 2012 09:45 - 10:45 @ Auditorium 

Gut reactions: Immune pathways in the intestine in health and disease

Abstract:

The gastrointestinal (GI) tract is home to a large number and vast array of bacteria that play an important role in nutrition, immune system development and host defense. In inflammatory bowel disease (IBD) there is a breakdown in this mutualistic relationship resulting in aberrant inflammatory responses to intestinal bacteria. Studies in model systems indicate that intestinal homeostasis is an active process involving a delicate balance between effector and immune suppressive pathways. The cytokine IL-23 plays a pivotal role in orchestrating intestinal inflammation and several genes in the IL-23/Th17 pathway confer risk to IBD. We have recently shown that IL-23 acts directly on T cells to promote pathological Th17 type responses at the expense of immune suppressive regulatory T cells. In addition IL-23 drives a novel population of innate lymphoid cells (ILC) that mediate colitis through the production of Th17 associated cytokines. Like Th17 cells, IL-23 driven ILC are dependent on the transcription factor RORγt indicating striking functional parallels between innate and adaptive lymphoid populations in the gut. In this presentation I will review our recent data that highlight the multiple activities of IL-23 that mediate tissue inflammatory responses and in some cases tumourigenesis.