Effects of Selenium Supplement on B Lymphocyte Activity in Experimental Autoimmune Thyroiditis Rats

Background and Objective. Thyroid is the organ with the highest selenium content in mammals, and selenium is an essential micronutrient that has close relationship with thyroid autoimmunity. However, the mechanism of how selenium modulates autoimmune thyroiditis remains to be elucidated. Thyroglobulin antibody (TGAb) and thyroid peroxidase antibody (TPOAb), which are produced by B lymphocytes, play a crucial role in autoimmune thyroiditis. The present study was aimed to investigate the effects of selenium supplement on thyroid autoimmunity and B lymphocyte activity in experimental autoimmune thyroiditis (EAT) model rats. Methods. 45 healthy and adult female SD rats were randomly divided into three groups: normal control group, EAT model group, and selenium yeast supplement EAT group. The EAT model rats were induced by subcutaneous injection of porcine thyroglobulin and fed with high iodine water. The concentrations of serum thyroid-stimulating hormone (TSH), TGAb, TPOAb, and B cell activating factor (BAFF) were detected in each group by enzyme-linked immunosorbent assay (ELISA), and the expression of interleukin-10 (IL-10) in thyroid tissue was detected by immunohistochemistry. B cells and regulatory B cells (Bregs) ratios in the spleen of rats were analyzed by flow cytometry. Results. In contrast with the EAT model group, the levels of serum TSH, TGAB, TPOAb, and BAFF were decreased, while IL-10 expression was increased in thyroid tissue, and Bregs ratio was upregulated in the spleen (all p < 0.05 ) in the selenium yeast supplement EAT group. Conclusion. Selenium yeast supplement could partially attenuate immune imbalance in EAT rats, which may be related to the mechanism of modulating B lymphocyte activity.

Yanghe Decoction Suppresses the Experimental Autoimmune Thyroiditis in Rats by Improving NLRP3 Inflammasome and Immune Dysregulation

Inflammation is an important contributor to autoimmune thyroiditis. Yanghe decoction (YH) is a traditional Chinese herbal formulation which has various anti-inflammatory effects. It has been used for the treatment of autoimmune diseases such as ankylosing spondylitis In this study we aimed to investigate the effects of YH on autoimmune thyroiditis in a rat model and elucidate the underlying mechanisms. The experimental autoimmune thyroiditis (EAT) model was established by thyroglobulin (pTG) injections and excessive iodine intake. Thyroid lesions were observed using hematoxylin and eosin (H and E) staining and serum TgAb, TPOAb, TSH, T3, and T4 levels were measured by enzyme-linked immunosorbent assay IL-35 levels were evaluated using real-time polymerase chain reaction (RT-PCR) and Th17/Treg balance in peripheral blood mononuclear cells (PBMCs) was determined by flow cytometry and RT-PCR. Changes in Wnt/β-catenin signaling were evaluated using Western blot. Immunofluorescence staining and western blot were employed to examine NLRP3 inflammasome activation in the thyroid. YH minimized thyroid follicle injury and decreased concentrations of serum TgAb, TPOAb, TSH, T3, and T4 in EAT model. The mRNA of IL-35 was increased after YH treatment. YH also increased the percentage of Treg cells, and decreased Th17 proportion as well as Th17/Treg ratio in PBMCs. Meanwhile, the mRNA levels of Th17 related cytokines (RORγt, IL-17A, IL-21, and IL-22) were suppressed and Treg related cytokines (FoxP3, TGF-β, and IL-10) were promoted in PBMCs. Additionally, the protein expressions of Wnt-1 and β-catenin were unregulated after YH treatment. NLRP3 immunostaining signal and protein levels of IL-17, p-NF-κB, NLRP3, ASC, cleaved-Caspase-1, cleaved-IL-1β, and IL-18 were downregulated in the thyroid after YH intervention. Overall, the present study demonstrated that YH alleviated autoimmune thyroiditis in rats by improving NLRP3 inflammasome and immune dysregulation.