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 antigens—including 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.