Regulatory B Cells Involvement in Autoimmune Phenomena Occurring in Pediatric Graves' Disease Patients

Characterizing the Interplay of Lymphocytes in Graves' Disease

Graves' disease (GD) is a thyroid-specific autoimmune disease with a high prevalence worldwide. The disease is primarily mediated by B cells, which produce autoantibodies against the thyroid-stimulating hormone receptor (TSHR), chronically stimulating it and leading to high levels of thyroid hormones in the body. Interest in characterizing the immune response in GD has motivated many phenotyping studies. The immunophenotype of the cells involved and the interplay between them and their secreted factors are crucial to understanding disease progression and future treatment options. T cell populations are markedly distinct, including increased levels of Th17 and follicular helper T cells (Tfh), while Treg cells appear to be impaired. Some B cells subsets are autoreactive, and anti-TSHR antibodies are the key disease-causing outcome of this interplay. Though some consensus across phenotyping studies will be discussed here, there are also complexities that are yet to be resolved. A better understanding of the immunophenotype of Graves' disease can lead to improved treatment strategies and novel drug targets.

Comprehensive immunophenotypic analysis reveals the pathological involvement of Th17 cells in Graves' disease

Graves' disease (GD) is an organ-specific autoimmune disease, but there are a few studies that have evaluated how immunophenotypes are related to clinical symptoms and intractable pathology, or the effects of treatment on immunophenotypes. We performed peripheral blood immunophenotyping in GD. We assessed the proportion of functional subsets of T helper cells (such as Th1, Th17, Treg and Tfh cells), B cells (Naïve, IgM memory, Class-switched, IgD⁻CD27⁻ double negative and Plasmablasts cells), Monocytes, Dendritic cells and NK cells, and evaluated the relationship of immunophenotypes with clinical indices, disease activity, risk of relapse, and changes in immunophenotypes after treatment with antithyroid drugs. The activated Th17 cells, activated T follicular helper (Tfh) cells, and IgD⁻CD27⁻ double-negative B cells were higher in newly onset GD compared with healthy participants. Th17 cells were associated with thyroid autoantibodies, thyroid function, thyroid enlargement, and Graves' Recurrent Events After Therapy (GREAT) score; while double-negative B cells were associated with thyroid autoantibodies. Treatment with antithyroid drugs decreased the activated Tfh cells in parallel with the improvement in thyroid function. However, activated Th17 cells were not associated with clinical improvement and remained unchanged. Peripheral blood immunophenotyping identified the differential involvement of T and B cell subsets in the pathogenesis of GD. Abnormalities in the differentiation of Th17, Tfh, and double-negative B cells reflected the clinical pathology associated with autoantibody production and excess thyroid hormones. And Th17 cells are significantly associated with the marker for resistance to treatment. These results suggest the involvement of Th17 cell activation in the intractable pathology associated with potential immune abnormalities in GD.

Clinical trial registration: #UMIN000017726 (Date: June 1st, 2015).