Human blood and mucosal regulatory T cells express activation markers and inhibitory receptors in inflammatory bowel disease

Background: FOXP3+ regulatory T cells (Tregs) are critical for preventing intestinal inflammation. However, FOXP3+ T cells are paradoxically increased in the intestines of patients with the inflammatory bowel disease (IBD) ulcerative colitis (UC) or Crohn's disease (CD). We determined whether these FOXP3+ cells in IBD patients share or lack the phenotype of such cells from patients without IBD. Methods: We quantified and characterized FOXP3+ Treg populations, as well as FOXP3- CD4+ T cells, in the lamina propria lymphocytes (LPL) of intestine surgically resected from patients with and without IBD, and in the blood of controls or Crohn's patients with or without disease activity. Results: In all samples, a similar fraction of FOXP3+ cells expressed the \"natural\" Treg (nTreg) marker Helios, suggesting that, in IBD, these cells are not entirely \"induced\" Tregs (iTregs) derived from activated effector T cells. Helios+ and Helios- FOXP3+ T cells demonstrated similar expression of matu...