Dysregulation of Vitamin D and Its Signaling in Hashimoto's Thyroiditis in Korean Population

Hahimoto’s thyroiditis (HT) is the most common thyroid disease leads to hypothyroid in developed countries. Recent studies highlighted the Vitamin D as the potential risk factor or the therapeutic agents for the HT due to its role in modulating immune responses, while the concrete evidence has not been presented. Patients eligible for the surgery of papillary thyroid cancer (PTC) with or without HT were recruited for the study. We analyzed serum thyroid biomarkers including serum vitamin D, anti-TG, anti-TPO for HT patients. Using the RNA-seq the gene expression profile of thyroid tissue, potential correlation between HT and vitamin D or its signaling was investigated. HT cohort showed common clinical characteristics known for the HT in serum biomarkers and enrichment analysis of BP terms and KEGG pathways. Serum vitamin D level was significantly lower in HT patients. However, vitamin D receptor (VDR) expression and genes involved in vitamin D-associated BP terms were significantly upregulated in HT. Real-time PCR and Immunofluorescence staining confirmed enhanced VDR expression throughout the thyroid tissue of HT cohort. This study demonstrated dysregulated vitamin D signaling in thyroid tissue of HT cohort. Further study need to be performed to elucidate etiology, susceptibility, and development of HT in relation with vitamin D signaling.