VSL#3 treatment enhanced the percentages of IL-17-expressing CD4+ T cells in the mucosal inductive site (i.e., MLN) and Foxp3-expressing CD4+ T cells in the effector site in mice with CRC, suggesting a possible role in modulating the plasticity between Th17 and Treg in the MLN and colonic LP. Here, IL17A is linked to colorectal carcinoma.