Harnessing Regulatory T Cells for the Treatment of Inflammatory Bowel Disease

Regulatory CD4(+) T (T-reg) cells are comprised of a heterogeneous population of cells that play a vital role in suppressing inflammation and maintaining immune tolerance. The immunoregulatory function of T-reg cells is especially important in the intestine where the mucosa is exposed to a diverse array of foreign antigensincluding those derived from food and commensal bacteria. T-reg cells are enriched in the intestinal lamina propria and provide a crucial function in promoting tolerance to enteric antigens while modulating tissue inflammation. Correspondingly, T-reg cell dysfunction is associated with a breakdown in intestinal tolerance and the induction of aberrant immune responses that may contribute to the pathogenesis of inflammatory bowel disease. This review will provide a brief overview of T-reg cell biology with a focus on Foxp3(+) T-reg and type 1 regulatory (Tr1) cells and summarize the evidence for defective T-reg cells in experimental and human inflammatory bowel disease. The potential application of T-reg cells as a treatment for inflammatory bowel disease will also be discussed in the context of T-reg infusion therapy and the in vivo induction/expansion of intestinal T-reg cells.