Indoleamine 2,3-dioxygenase: expressing cells in inflammatory bowel disease-a cross-sectional study

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.

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.

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.

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.