Introduction: Zinc homeostasis is regulated by ZnT and Zip zinc transporters. Zinc transporter 8 (ZnT8) is localized in insulin containing secretory granule membrane and transports zinc from the cytosol into the vesicles. ZnT8 was identified on peripheral lymphocytes, in subcutaneous adipose tissue, in a pancreatic β-cells and extra-pancreatic endocrine glands including pituitary, adrenal and thyroid. Autoantibodies to the ZnT8 are detected in the majority of type 1 diabetes patients. A few recent studies showed that ZnT8 Ab may occur in patients with autoimmune thyroid diseases. There is lack of data about expression of ZnT8 transporter in human thyroid tissues.
Aim of the study: To compare the expression of ZnT8 transporter in thyroid tissues from patients with immune and non-immune thyroid diseases.
Material and methods: The study was performed in thyroid tissues after thyroidectomy from patients with thyroid nodular goiter (n=17, mean age 17.8 years ±4) and cases with Graves disease (n=20, mean age15.6 years ±2.8). The ZnT8 expression protein was evaluated using immunohistochemistry. The specimens were paraffin embedded tissues, derived from the pediatric patients, who had thyroid nodular goiter or GD. The antibody against ZnT8 was goat polyclonal antibody (Santa Cruz Biotechnology USA; sc-98243). The antigen was retrieval was done using high pH (PTLink DAKO) and antibody was incubated in 4 °C overnight in 1:50 dilution. The patients with pancreatitis were as positive controls. The intensity and the proportion of stained cells were determined by examining the entire slide and section as: + (low staining intensity in less than 10% cells in the section);++ (moderate staining intensity in 10-40% cells in the section);+++ (high and diffuse staining intensity in more than 50% cells in the section).
Results: The staining intensity of examined cells in thyroid tissues from patients with: thyroid nodular goiter ++; C cells hyperplasia ++; GD +++. The positive control (patients with pancreatitis) +++.
Conclusions: Expression of ZnT8 transporter was identified in the thyroid tissues from paediatric patients with Graves disease and nontoxic nodular goiter and was found both in thyroid follicular cells and C cells. Predominant expression of ZnT8 in immune than in non-immune thyroid disorders may suggest potential role of ZnT8 as a new thyroid autoantigen but it requires further study on a larger cohort.
27 - 29 Sep 2018
European Society for Paediatric Endocrinology