A study of programmed death-1/programmed death ligand and iodine-induced autoimmune thyroiditis in NOD.H-2h4 mice

Effect of decitabine on PD-L2 methylation in whole blood of iodine-induced autoimmune thyroiditis rats

Excessive iodine intake can induce autoimmune thyroiditis (AIT), and the methylation of programmed death receptor 2 (PD-L2) may be involved in the development of iodine-induced AIT. Here, we investigated the immune role of methylation of the susceptibility gene PD-L2 in the occurrence of iodine-induced AIT using the DNA methyltransferase inhibitor Decitabine (Dec) in an experimental autoimmune thyroiditis (EAT) rat model. After injecting Dec intraperitoneally into EAT rats, we performed arsenic-cerium catalytic spectrophotometry, pathological hematoxylin and eosin staining, enzyme-linked immunosorbent assay, quantitative methylation-specific polymerase chain reaction (qMSP), and quantitative real-time polymerase chain reaction (qPCR) to determine the relevant indices. The results showed that compared with the control group, the urinary iodine, thyroid lymphocyte infiltration, thyroglobulin antibody (TgAb), interferon (IFN-γ), and interleukin (IL-23) levels of the EAT rats were significantly increased. The PD-L2 methylation levels were significantly decreased in EAT rats compared to control rats, and the mRNA expression of the PD-L2 was significantly increased. Following Dec intervention, the methylation level of the PD-L2 in rats increased and interferon and interleukin-23 levels decreased, albeit not significantly. However, the mRNA expression of PD-L2 decreased significantly after Dec intervention, and the thyroid function of EAT rats also showed a gradual improvement trend. In summary, hypomethylation of PD-L2 is closely related to the development of iodine-induced AIT. Pro-inflammatory cellular factors are also involved in iodine-induced AIT progression. Although Dec shows promise in the treatment of AIT, further evaluation of its safety is necessary.

The association between endothelial function and autoimmune thyroiditis induced by iodine excess

BACKGROUND

Iodine excess (IE) intake leads to lymphocyte dysfunction and contributes to autoimmune thyroiditis (AIT). Abnormal thyroid function is associated with adverse cardiovascular events, endothelial dysfunction is often an early pathophysiological feature in most cardiovascular disease. However, the relationship between iodine and the cardiovascular system is currently unclear. Therefore, the aim of this study was to investigate the effects of IE on endothelial function in mouse model.

METHODS

A total of 24 NOD.H-2h4 mice were randomly divided into different groups. A sodium iodide (NaI) group supplied with 0.05% NaI water for 8 weeks. Serum levels of tumor necrosis factors α (TNFα), interleukin-6 (IL-6) and C-reactive Protein (CRP), as well as endothelin-1 (ET-1), von Willebrand factor (VWF) and thrombomodulin (THBD) were detected by Elisa. In addition, the mRNA and protein expression of these genes were measured by RT-PCR and Western blotting.

RESULTS

Here, we found the urinary iodine concentration (UIC) was higher in the NaI group compared to the control group. Serum levels of ET-1, VWF, and THBD were also significantly lower in the NaI group, however, CRP serum levels are significantly increased. In aorta, the mRNA and protein expression of ET-1, VWF, THBD were downregulated, however, the expression of IL-6, CRP and TNFα mRNA and protein were upregulated in the NaI group. A correlation analysis showed negative correlation between UIC with ET-1, VWF, and THBD, similarly, negative correlation between CRP with THBD was observed. In addition, positive correlations between UIC with CRP.

CONCLUSION

Collectively, in the NOD.H-2h4 mice, IE supplementation had a suppressive effect on endothelial function, and this inhibition maybe due to the increase expression of inflammatory cytokines.