ESPE Abstracts

Introduction: There has been a growing trend in the incidence of autoimmune thyroid diseases (ATD) in the pediatric group of patients. The new aspects of its pathogenesis may contribute to understand innovative methods of prevention and treatment. Regulatory B cells (Breg) allow the maintenance of immune homeostasis by neutralizing the negative reactions of effector cells. Attention has been recently paid also to the new environmental factor like zinc and its receptor- ZnT8, that may have properties to support the functionality of T and B cells.

Aim: The aim of this study was to assess the percentage of Breg with the specific phenotypes in children with ATD, to evaluate the effect of treatment on the percentage of Breg and effector cells and to assess the ZnT8 expression in thyroid tissue in patients after thyroidectomy due to Graves’ disease (GD).

Material and Methods: The study consisted of 3 different research groups: the first with 53 patients with ATD (12- GD and 10 with Hashimoto's thyroiditis- HT) and 15 healthy control, the second group consisted of 17 patients with non-toxic nodular goitre (NTNG) and 20 with GD after thyroidectomy and the third consisted of 22 GD patients treated with methimazole, compared to 31 healthy control. Cells were analyzed using a BD FACS Calibur cytometer and FlowJo software. The obtained data were processed using the statistical software GraphPad Prism 5.0 and Statistica 12.0. ZnT8 expression in human thyroid tissues was investigated by simultaneous immunohistochemical, Western Blot and immunofluorescence analyses.

Results: There was a decrease in IL-10 production by Breg cells expressing CD19+CD24+CD27+IL-10 and CD1d+CD5+CD19+IL-10+ in both untreated and treated ATD patients. Significantly higher levels of Th1, Th17 and Th22 effector cells were found in patients with GD. Thiamazole did not significantly affect the changes within the examined cells. Patients with GD showed significant correlations between Breg and Th1 and Th17 cells. Expression of the ZnT8 transporter was identified by immunohistochemistry in thyroid tissues of patients with GD and NTNG. This expression was found in follicular and C cells by fluorescence method.

Conclusion: The reduction in the level of Breg lymphocytes with the CD19+CD24+CD27+IL-10+ and CD19+IL-10 phenotype may be responsible for the violation of immune tolerance in the course of GD. The presence of ZnT8 expression in the thyroid tissue of patients with GD may suggest the potential role of this transporter as another autoantigen.