PD-1/PD-L1 Expressions on Treg Cells in Patients with Autoimmune Thyroid Disease

Background: Autoimmune thyroid disease(AITD) is a frequent autoimmune disease characterized by lymphocytic infiltration and thyroid autoantibody production caused by autoimmune dysfunction. Recent studies have shown that Treg cells can participate in the pathogenesis of AITD by inhibiting peripheral reactive T cells and thereby inhibiting the autoimmune responses. Programmed cell death-1 (PD-1)/programmed cell death ligand (PD-L1) pathway is a negative costimulatory pathway discovered in recent years, enhancing or blocking this pathway is associated with the immune process of AITD. PD-1/PD-L1 was simultaneously expressed on Treg cells. In this paper, the role of regulatory T cells and PD-1/PD-L1 signaling pathway in AITD was discussed. Methods: We detected the percentage of CD4+CD25+CD127lowT cells, the ratio of PD-1+Treg cells and PD-L1+Treg cells in peripheral blood of twenty patients newly diagnosed with graves disease (GD) and twenty-one patients newly diagnosed with Hashimotos’thyroiditis (HT) patients by flow cytometry, and samples from twenty healthy individuals served as control. Results: The results demonstrated that the proportion of CD4+CD25+CD127lowT cells in peripheral blood of HT patients was lower than that of healthy controls(HCs), the ratio of PD-1+Treg cells of HT patients was higher than that of the HCs and GD patients, the ratio of PD-1+Treg cells of GD patients was higher than that of the HCs, the ratio of PD-L1+Treg cells in Treg cells of HT patients was higher than that of the HCs and GD patients and the ratio of PD-L1+Treg cells of GD patients was higher than that of the HCs. All the above were statistically significant. Conclusions: The treg cells play an obvious role in hashimoto's thyroiditis, but not obvious in Graves' disease.