Issues

Geis and colleagues found that depletion of regulatory T cells (Treg) unexpectedly impaired early microadenoma formation in multiple intestinal neoplasia mice colonized by the bacterium enterotoxigenic Bacteroides fragilis (ETBF). This reduction in neoplastic growth was accompanied by a decrease in Th17 cells and IL17 production and an increase in the IFNγ-producing Th1 cell population, suggesting that Tregs modulate the balance of Th1/Th17 cells. Treg consumption of IL2 resulted in an increase in Th17 polarization and a subsequent decrease in the Th1 population following ETBF colonization, consistent with a cell-extrinsic role for Tregs in promoting Th17 differentiation. These results demonstrate that Tregs drive Th17 polarization to establish protumorigenic colitis and are necessary for the early stages of tumorigenesis in colitis-associated colorectal cancer. For details, please see the article by Geis and colleagues on page 1098.