BACKGROUND:The purpose of present study was to investigate mitochondrial DNA copy number (mtDNAcn) and mtDNA damage in peripheral blood of patients with Hashimoto's thyroiditis (HT) and healthy controls (HC). METHODS:The relative mtDNAcn and oxidative DNA damage in this case-control study were measured in peripheral blood of 50 patients with Hashimoto's thyroiditis and 50 healthy controls using quantitative real-time PCR. The study was conducted in Tehran University of Medical Sciences hospital, Tehran, Iran in 2018. RESULTS:HT patients had significantly higher mitochondrial DNA copy number and mitochondrial oxidative damage than the comparison group. CONCLUSION:These data suggest the possible involvement of mitochondria and oxidative stress in the pathophysiology of HT.

BACKGROUND:The prevalence of Hashimoto's thyroiditis (HT) among women with polycystic ovary syndrome (PCOS) is higher than in the general female population, but the factors predisposing to the coexistence of these disorders remain unclear. This study employed whole genome sequencing of mitochondrial DNA to identify genetic variants potentially associated with the development of PCOS and HT and predisposing to their joint occurrence. RESULTS:A total of 84 women participated, including patients with PCOS, HT, coexisting PCOS and HT (PCOS + HT) and healthy women. Both Fisher's exact and Mann-Whitney U statistical analyses were performed to compare the frequency of variants between groups. Ten differentiating variants were common to both analyses in PCOS + HT vs. PCOS, one in PCOS + HT vs. HT, and six in PCOS + HT vs. control. Several variants differentiating the PCOS + HT group from PCOS and controls were identified, located both in the mitochondrial genes (including the , , , , , , ) and the D-loop region. Only two variants differentiated PCOS + HT and HT groups. One variant (13237a in ) was common for all three comparisons and underrepresented in the PCOS + HT group. Functional enrichment analysis showed 10 pathways that were unique for the comparison of PCOS + HT and PCOS groups, especially related to ATP production and oxidative phosphorylation, and one pathway, the NADH-quinone oxidoreductase, chain M/4, that was unique for the comparison of PCOS + HT and control groups. Notably, nine pathways shared commonality between PCOS + HT vs. PCOS and PCOS + HT vs. control, related to the biogenesis and assembly of Complex I. CONCLUSION:This study provides novel insights into the genetic variants associated with oxidative stress in women with coexisting PCOS and HT. Mitochondrial dysfunction and oxidative stress appear to play a role in the pathogenesis of both conditions. However, more mitochondrial variants were found to differentiate women with both PCOS and HT from those with PCOS alone than from those with HT alone.

Hashimoto thyroiditis (HT), now considered the most common autoimmune disease, was described over a century ago as a pronounced lymphoid goiter affecting predominantly women. In addition to this classic form, several other clinico-pathologic entities are now included under the term HT: fibrous variant, IgG4-related variant, juvenile form, Hashitoxicosis, and painless thyroiditis (sporadic or post-partum). All forms are characterized pathologically by the infiltration of hematopoietic mononuclear cells, mainly lymphocytes, in the interstitium among the thyroid follicles, although specific features can be recognized in each variant. Thyroid cells undergo atrophy or transform into a bolder type of follicular cell rich in mitochondria called Hürthle cell. Most HT forms ultimately evolve into hypothyroidism, although at presentation patients can be euthyroid or even hyperthyroid. The diagnosis of HT relies on the demonstration of circulating antibodies to thyroid antigens (mainly thyroperoxidase and thyroglobulin) and reduced echogenicity on thyroid sonogram in a patient with proper clinical features. The treatment remains symptomatic and based on the administration of synthetic thyroid hormones to correct the hypothyroidism as needed. Surgery is performed when the goiter is large enough to cause significant compression of the surrounding cervical structures, or when some areas of the thyroid gland mimic the features of a nodule whose cytology cannot be ascertained as benign. HT remains a complex and ever expanding disease of unknown pathogenesis that awaits prevention or novel forms of treatment.

Background:Although the pathogenetic mechanisms of Hashimoto's thyroiditis (HT) and Graves' disease (GD) have been elucidated, the molecular mechanisms by which the abnormal immune function of cellular subpopulations trigger an autoimmune attack on thyroid tissue largely remains unexplained. Methods:The study included 2 HT patients, 2 GD patients, and 1 control donor. The thyroid samples were extracted for single-cell RNA sequencing, whole transcriptome, full-length transcriptome (Oxford Nanopore Technologies), and metabolome sequencing. Identification of immune cells with dysregulated gene expression and abnormal metabolic signaling was performed in the microenvironment, both at the bulk and single-cell levels. Based on functional enrichment analysis, the biological processes and pathways involved in abnormal immune cells were further explored. Finally, according to cell communication analysis, the global regulatory network of immune cells was constructed. Results:CD4 T cells, CD8 T cells, and macrophages were abnormally increased in patients with HT and GD. The differentially expressed genes of these cells were significantly involved in signaling pathways, including Th1 and Th2 cell differentiation, Th17 cell differentiation, cytokine-cytokine receptor interaction, and NF-kappa B signaling pathway. Moreover, in HT, CD4 T cells interact with macrophages the IL16-CCR5/FGF10-FGFR1/CXCL13-CXCR3 axis, and macrophages interact with CD8 T cells the CD70-CD27 axis, thereby activating the T-cell receptor signaling pathway and NF-kappa B signaling pathway. In GD, CD4 T cells interact with macrophages the CXCR3-CXCL10/PKM-CD44/MHCII-NFKBIE axis, and macrophages interact with CD8 T cells the IFNG-IFNGR1/CCR7-CCL21 axis, thereby activating T-cell receptor signaling pathway, Th1 and Th2 cell differentiation, and chemokine signaling pathway. Conclusion:In HT and GD, immune dysregulated cells interact and activate relevant immune pathways and further aggravate the immune response. This may trigger the immune cells to target the thyroid tissue and influence the development of the disease.

Hashimoto's thyroiditis (HT) is the most common autoimmune disease characterized by lymphocytic infiltration and thyrocyte destruction. Dissection of the interaction between the thyroidal stromal microenvironment and the infiltrating immune cells might lead to a better understanding of HT pathogenesis. Here we show, using single-cell RNA-sequencing, that three thyroidal stromal cell subsets, ACKR1 endothelial cells and CCL21 myofibroblasts and CCL21 fibroblasts, contribute to the thyroidal tissue microenvironment in HT. These cell types occupy distinct histological locations within the thyroid gland. Our experiments suggest that they might facilitate lymphocyte trafficking from the blood to thyroid tissues, and T cell zone CCL21 fibroblasts may also promote the formation of tertiary lymphoid organs characteristic to HT. Our study also demonstrates the presence of inflammatory macrophages and dendritic cells expressing high levels of IL-1β in the thyroid, which may contribute to thyrocyte destruction in HT patients. Our findings thus provide a deeper insight into the cellular interactions that might prompt the pathogenesis of HT.