Indoleamine 2,3-Dioxygenase: Expressing Cells in Inflammatory Bowel Disease—A Cross-Sectional Study

AIM To characterise and enumerate IDO(+) cells, Tregs, and T cell subsets in patients with ulcerative colitis (UC) and Crohn's disease (CD) with regard to their clinical activity. METHODS Ten active UC (aUC), 10 inactive UC (iUC), 6 aCD, and 8 iCD patients and 10 healthy individuals were included in the study. Circulating Foxp3-, IDO-, IL-17A-, IL-4-, IFN- γ -, and IL-10-expressing CD4(+) T cells were quantitated by flow cytometry. Interleukin-17-expressing cells, CD25(+)/Foxp3(+) Tregs, and CD123(+)/IDO(+) plasmacytoid dendritic cells were evaluated in intestinal biopsies from 10 aUC, 6 aCD, and 10 noninflamed tissues. RESULTS All CD4(+) T subsets were increased in aIBD patients compared with healthy donors. Meanwhile, frequency of CD8 α (+)/CD16(+)/IDO(+), CD8 α (+)/CD56(+)/IDO(+), CD8 α (+)/CD80(+)/IDO(+), CD8 α (+)/CD123(+)/IDO(+) large granular nonlymphoid cells, and CCR6(+)/CD123(+)/IDO(+) plasmacytoid dendritic cells was higher in aIBD patients versus healthy donors or iIBD patients. Tissue IL-17A(+) cells were present in higher amounts in aIBD versus noninflamed controls. IDO- and Foxp3-expressing cells were increased in aUC versus aCD patients and noninflamed tissues. CONCLUSIONS The findings represent an original work in Mexican Mestizo patients with IBD. It shows that Tregs and IDO-expressing cells are increased with regard to disease activity. These cells could significantly shape inflammatory bowel disease pathophysiology, severity, and tolerance loss.