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The essence of autoimmune thyroid disease (AITD) is loss of tolerance of own tissues caused by malfunction of T lymphocytes, which affects the production of antibodies reacting with particular cell structures and tissues. Foxp3+ regulatory T cells (Tregs) take part in the regulation of immune response and play a leading role in developing immune tolerance through active suppression. The aim of the study was to estimate the expression of CD4+CD25high, CD4+CD25+CD127lowFoxP3+ and CD4+ FoxP3 T cells in patients with Graves' disease (GD) ( n = 24, median age 15.5 years), in patients with Hashimoto's thyroiditis (HT) ( n = 30, median age 15 years) in comparison with sex- and age-matched healthy control subjects ( n = 30, median age 15 years). Polychromatic flow cytometry using a FACSCalibur (BD Biosciences) cytometer was applied to delineate T regulatory cell populations. In untreated patients with Graves' disease and HT we observed a significant decrease in CD4+FoxP3 ( p < 0.001, p < 0.01) and CD4+CD25high ( p < 0.016, p < 0.048) T lymphocytes as compared to the healthy control subjects. After 6-12 months of L-thyroxine therapy in HT cases these phenotypes of Tregs were normalized, yet no such changes were observed during GD therapy. The analysis of CD4+CD25+CD127lowFoxP3+T cells in the peripheral blood revealed comparable percentages of these cells in patients with thyroid autoimmune diseases to the controls. We conclude that the reduction number of Tregs with CD4+CD25high and CD4+FoxP3 phenotype suggests their role in initiation and development of autoimmune process in thyroid disorders. [ABSTRACT FROM AUTHOR]

Introduction: As it is generally known, regulatory B cells (Bregs) control inflammation and autoimmunity. The significance of Bregs in the population of children with autoimmune thyroid diseases (AITD) still offers plenty of potential to explore. The aim of this study was to estimate the expression of Bregs (phenotype CD19 + CD24 + CD27 + IL-10 + , CD19 + IL-10 + , CD1d + CD5 + CD19 + IL-10 + and CD1d + CD5 + CD19 + CD24 + CD27 + ) in a paediatric cohort with AITD and in health controls. Materials and methods: A total of 100 blood samples were obtained from 53 paediatric patients with Graves' disease (GD) ( N  = 12 newly diagnosed, mean age 12.5 ± 3.5 and N  = 17 during methimazole therapy, mean age 12.7 ± 4.4), Hashimoto's thyroiditis (HT) ( N  = 10 newly diagnosed, mean age 13.3 ± 2.9 and N  = 10 during L-thyroxine therapy, mean age 13.7 ± 3.4) and compared with healthy controls (C) ( N  = 15, mean age 13.1 ± 3.1). The expressions of the immune cell populations were analysed by four-color flow cytometry using a FASC Canto II cytometer (BD Biosciences). Results: There was a decreasing tendency in the number of lymphocytes B producing IL-10 (B10) cells among all B lymphocytes and more widely, also among all lymphocytes, in each study group, as compared to C. We reported a reduction in IL-10 production in Bregs with the expression of CD19 + CD24 + CD27 + IL-10 and CD1d + CD5 + CD19 + IL-10 + in both untreated and treated AITD. Conclusions: Our data demonstrate that the reduction in the number of Bregs with CD19 + CD24 + CD27 + IL-10 + and CD19 + IL-10 + expression could be responsible for breaking immune tolerance and for AITD development in children.

Until now, altered balance of Th1 and Th2 immune cells has been postulated to play an important role in the pathogenesis of autoimmune thyroid diseases (AITD). However, recent studies on thyroid diseases have suggested a new role for Th17 cells that have been classified as a new lineage, distinct from Th1, Th2 and Treg cells. Despite wide interest, the role of Th17 cells in the pathogenesis of inflammatory and autoimmune diseases is still debated. The aim of the study was to estimate the proportions of Th17/Treg T cells in peripheral blood from patients with Graves' disease (GD; n = 29, mean age 15.4 ± 5.1 years), Hashimoto's thyroiditis (HT; n = 39, mean age 15.2 ± 4.1 years) and in healthy controls (n = 49, mean age 14.8 ± 3 years). Polychromatic flow cytometry and several fluorochrome-conjugated monoclonal antibodies were applied to delineate Th17 and Treg cells. The analysis of Th17/Treg T cell proportions in peripheral blood from patients with Graves' disease revealed significantly lower ratios of CD4 + IL17+/CD4 + CD25 + CD127 - (p < 0.0021) and CD4 + IL17+/CD4 + CD25 + CD127 - FoxP3 + (p < 0.0031) than in the control group. In addition, in the case of HT, we observed a significant decrease in the ratios of CD4 + IL17+/CD4 + CD25 + CD127 - (p < 0.0001) and CD4 + IL17+/CD4 + CD25 + CD127 - FoxP3 + (p < 0.0001) T cells in comparison to healthy children. In patients with untreated GD, a statistically significant positive correlation was found between the proportions of CD4 + IL17+/CD4 + CD25 + CD127-, CD4 + IL17+/CD4 + CD25 + CD127 - FoxP3+ T cells and the TRAbs (R = 0.71, p < 0.029; R = 0.72, p < 0.026, respectively) and a positive correlation was noted between the percentage of CD4 + CD - IL - 17 + T cells and the level of TSAbs (R = 0.66, p < 0.037). We conclude that the changes in the proportion of Th17/Treg T cells in peripheral blood and their significant relationship with the level of anti-thyroid antibodies indicate an involvement of these cells in the pathogenesis of AITD.

The essence of autoimmune thyroid disease (AITD) is loss of tolerance of own tissues caused by malfunction of T lymphocytes, which affects the production of antibodies reacting with particular cell structures and tissues. Foxp3(+) regulatory T cells (Tregs) take part in the regulation of immune response and play a leading role in developing immune tolerance through active suppression. The aim of the study was to estimate the expression of CD4+CD25(high), CD4+CD25+CD127(low)FoxP3(+) and CD4+ FoxP3 T cells in patients with Graves' disease (GD) (n = 24, median age 15.5 years), in patients with Hashimoto's thyroiditis (HT) (n = 30, median age 15 years) in comparison with sex- and age-matched healthy control subjects (n = 30, median age 15 years). Polychromatic flow cytometry using a FACSCalibur (BD Biosciences) cytometer was applied to delineate T regulatory cell populations. In untreated patients with Graves' disease and HT we observed a significant decrease in CD4+FoxP3 (p < 0.001, p < 0.01) and CD4+CD25(high) (p < 0.016, p < 0.048) T lymphocytes as compared to the healthy control subjects. After 6-12 months of L-thyroxine therapy in HT cases these phenotypes of Tregs were normalized, yet no such changes were observed during GD therapy. The analysis of CD4+CD25+CD127(low)FoxP3+ T cells in the peripheral blood revealed comparable percentages of these cells in patients with thyroid autoimmune diseases to the controls. We conclude that the reduction number of Tregs with CD4+CD25(high) and CD4+FoxP3 phenotype suggests their role in initiation and development of autoimmune process in thyroid disorders.