Decreased Frequencies of Peripheral Blood CD4+CD25+CD127-Foxp3+ in Patients with Graves' Disease and Graves' Orbitopathy: Enhancing Effect of Insulin Growth Factor-1 on Treg Cells.

Graves' orbitopathy (GO) is characterized by orbital T cell infiltration. We evaluated the regulatory T (Treg) cell fractions induced with IGF-1 in Graves' disease (GD) with and without GO. Peripheral blood mononuclear cells (PBMCs) were obtained from 13 patients with GD without eye manifestations; 10 patients with active GO; and 12 patients with nodular goiter (NG). All the patients from GD, GO, and NG were subclinical hyperthyroid. We analyzed the expression of Treg cell markers (CD4, CD25, CD127, Foxp3) on T cells and their ability to respond to IGF-1 stimulation. In patients with GD without GO, we found lowered percentages of CD4 Foxp3 cells, as compared to nodular goiter 1.77 vs. 5.42% (p=0.0276). Similarly, significantly reduced frequencies of CD4CD25CD127Foxp3 and CD4CD25CD127 cells were observed in GD patients as compared to nodular goiter patients with hyperthyreosis, (0.7 vs. 1.48%) (p=0.0071) and (14.5 vs. 37.2%) (p=0.0051), respectively. In GO with active GO, only the percentage of CD4CD25CD127 cells was found to be decreased versus nodular goiter (9.35 vs. 37.2) (p=0.0275). Stimulation of PBMC derived from GO patients with IGF-1 resulted in significant increase of frequency of both CD4 Foxp3 and CD4CD25CD127 Foxp3 cells. Decreased frequencies of peripheral blood CD4CD25CD127Foxp3 in patients with GD and GO could be an useful marker of autoimmune process and perhaps a possible target for future therapies. This is the first study demonstrating Treg-enhancing effects of IGF-1. Thus IGF-1 can be accounted for modulating Treg cell-related action in GO.