DNA Methylation Patterns in the HLA-DPB1 and PDCD1LG2 Gene Regions in Patients with Autoimmune Thyroiditis from Different Water Iodine Areas

Background: Epigenetic disorders play an important role in the pathogenesis of autoimmune thyroiditis (AIT). Therefore, the study of the possible role of DNA methylation in AIT is of great significance to explore the pathogenesis of AIT. Methods: From May 2019 to June 2019, whole blood samples were collected from 176 AIT patients and 176 controls from different water iodine levels in Shandong Province, China. We used the Illumina Methylation 850K BeadChip to determine significant differences in methylation status of genes and used the MethylTarget™ assay to verify the methylation level in 176 cases and 176 controls. The relative mRNA levels of genes were detected by quantitative real-time-polymerase chain reaction. Results: There were multiple differential methylation sites in the HLA-DPB1 and PDCD1LG2 genes between the case and control population with different water iodine levels. Some target regions of HLA-DPB1 and PDCD1LG2 genes were negatively correlated with relative mRNA expression in the case and control populations and with different water iodine levels. Conclusions: There is differential methylation status in genomic DNA in patients with AIT. The methylation patterns of HLA-DPB1 and PDCD1LG2 genes related to cell adhesion molecule pathway may be different based on different water iodine levels. HLA-DPB1 and PDCD1LG2 genes related to the cell adhesion molecules pathway may play a role in the development of AIT. This study is registered with Chinese Clinical Trial Registry, www.chictr.org.cn, number ChiCTR2000039105.