Epigenetics and Autoimmune Thyroid Diseases

Effect of DNA methylation at the CTLA4 gene on the clinical status of autoimmune thyroid diseases

The pathogenesis and manifestation of autoimmune thyroid diseases (AITDs), Graves' disease (GD), and Hashimoto's disease (HD) are associated with T cell activation. Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) plays a crucial role in the regulation of T cell activation. DNA methylation levels of eight CpG sites in the CTLA4 gene and expression levels of soluble CTLA-4 were examined. Methylation levels of +22 CpG and CT60 CpG-SNPs in patients with GD and HD with the CT60 GG genotype were lower than those in control subjects. Methylation levels of the-15 CpG sites were lower in patients with intractable GD than those in GD patients in remission. These results suggest that demethylation of +22 CpG and CT60 CpG-SNPs may be associated with susceptibility to GD and HD in subjects with the CTLA4 CT60 GG genotype, and that demethylation of -15 CpG may be associated with the intractability of GD.

The Effect of a Casein and Gluten-Free Diet on the Epigenetic Characteristics of FoxP3 in Patients With Hashimoto's Thyroiditis

Background Hashimoto's thyroiditis (HT) is an autoimmune thyroid disease characterized by inflammation and dysfunction of the thyroid gland, resulting in hypothyroidism, it results in impaired thyroid hormone generation and mimics hypothyroidism. The disease involves complex interactions among genetic, environmental, and epigenetic factors, particularly affecting the regulation of T regulatory (Treg) cells, including CD4 + foxp3 + T cells. Treg cells, defined as CD4 + T cells, rely on the expression of the foxp3 transcription factor, which is crucial for their development and differentiation. Disruptions in this regulation can lead to immune dysregulation and potential proinflammatory responses. The study focuses on investigating the impact of dietary patterns on the epigenetic changes in the foxp3 gene, a key player in the development of HT. The primary aim was to evaluate how eliminating gluten and casein proteins from dietary regimens may influence the methylation levels of the foxp3 gene, considering the potential link between these dietary components and the triggering of autoimmune diseases. Methods An epigenetic analysis of the foxp3 gene in HT patients who were strictly following a dietary plan compared with the control group. For the epigenetic study, a methylation analysis experiment was conducted.  Results Our findings revealed a notable reduction in foxp3 gene methylation levels among HT patients who adhered to a diet excluding casein and gluten. The control maintained normal dietary guidelines and showed no significant alterations in methylation levels. Discussion The laboratory values showed a decrease in methylation levels of the foxp3 gene, with statistical significance indicated as *p<0.005, **p<0.001, ***p<0.0001, suggesting a potential enhancement in its expression which could have profound implications for immune system regulation. Disruptions in the foxp3 pathway are crucial in the development of autoimmune disorders, where altered activity hinders the regulation of T cell (Treg) development, ultimately contributing to conditions like HT disease. These findings imply that nutritional interventions, especially for individuals with HT, could potentially be a strategy for mitigating autoimmunity through epigenetic mechanisms.

Methylation levels of the IL10 gene in peripheral blood are related to the intractability of Graves' disease

The prognosis of autoimmune thyroid diseases (AITDs), including Hashimoto's disease (HD) and Graves' disease (GD), is difficult to predict. DNA methylation regulates gene expression of immune mediating factors. Interleukin (IL)-10 is a Th2 cytokine that downregulates inflammatory cytokines produced by Th1 cells. To clarify the role of methylation of the IL10 gene in the prognosis of AITD, we evaluated the methylation levels of two CpG sites in the IL10 promoter using pyrosequencing. The methylation levels of the -185 CpG site of the IL10 gene were related to age and GD intractability in GD patients. Furthermore, the C carrier of the IL10-592 A/C polymorphism was related to low methylation levels of the -185 CpG site. The methylation levels of the IL10-185 CpG site of the IL10 gene were related to the intractability of GD and were lower in individuals with the C allele of the IL10-592 A/C polymorphism.

Association of autoimmune thyroid disease with type 1 diabetes mellitus and its ultrasonic diagnosis and management

As a common hyperglycemic disease, type 1 diabetes mellitus (T1DM) is a complicated disorder that requires a lifelong insulin supply due to the immune-mediated destruction of pancreatic β cells. Although it is an organ-specific autoimmune disorder, T1DM is often associated with multiple other autoimmune disorders. The most prevalent concomitant autoimmune disorder occurring in T1DM is autoimmune thyroid disease (AITD), which mainly exhibits two extremes of phenotypes: hyperthyroidism [Graves' disease (GD)] and hypo-thyroidism [Hashimoto's thyroiditis, (HT)]. However, the presence of comorbid AITD may negatively affect metabolic management in T1DM patients and thereby may increase the risk for potential diabetes-related complications. Thus, routine screening of thyroid function has been recommended when T1DM is diagnosed. Here, first, we summarize current knowledge regarding the etiology and pathogenesis mechanisms of both diseases. Subsequently, an updated review of the association between T1DM and AITD is offered. Finally, we provide a relatively detailed review focusing on the application of thyroid ultrasonography in diagnosing and managing HT and GD, suggesting its critical role in the timely and accurate diagnosis of AITD in T1DM.

Molecular Mechanisms in Autoimmune Thyroid Disease

The most common cause of acquired thyroid dysfunction is autoimmune thyroid disease, which is an organ-specific autoimmune disease with two presentation phenotypes: hyperthyroidism (Graves-Basedow disease) and hypothyroidism (Hashimoto's thyroiditis). Hashimoto's thyroiditis is distinguished by the presence of autoantibodies against thyroid peroxidase and thyroglobulin. Meanwhile, autoantibodies against the TSH receptor have been found in Graves-Basedow disease. Numerous susceptibility genes, as well as epigenetic and environmental factors, contribute to the pathogenesis of both diseases. This review summarizes the most common genetic, epigenetic, and environmental mechanisms involved in autoimmune thyroid disease.

DNA Methylation in Autoimmune Thyroid Disease

Graves disease and Hashimoto disease form part of the spectrum of autoimmune thyroid disease (AITD), to which genetic and environmental factors are recognized contributors. Epigenetics provides a potential link between environmental influences, gene expression, and thyroid autoimmunity. DNA methylation (DNAm) is the best studied epigenetic process, and global hypomethylation of leukocyte DNA is reported in several autoimmune disorders. This review summarizes the current understanding of DNAm in AITD. Targeted DNAm studies of blood samples from AITD patients have reported differential DNAm in the promoter regions of several genes implicated in AITD, including TNF, IFNG, IL2RA, IL6, ICAM1, and PTPN22. In many cases, however, the findings await replication and are unsupported by functional studies to support causal roles in AITD pathogenesis. Furthermore, thyroid hormones affect DNAm, and in many studies confounding by reverse causation has not been considered. Recent studies have shown that DNAm patterns in candidate genes including ITGA6, PRKAA2, and DAPK1 differ between AITD patients from regions with different iodine status, providing a potential mechanism for associations between iodine and AITD. Research focus in the field is moving from candidate gene studies to an epigenome-wide approach. Genome-wide methylation studies of AITD patients have demonstrated multiple differentially methylated positions, including some in immunoregulatory genes such as NOTCH1, HLA-DRB1, TNF, and ICAM1. Large, epigenome-wide studies are required to elucidate the pathophysiological role of DNAm in AITD, with the potential to provide novel diagnostic and prognostic biomarkers as well as therapeutic targets.

Follicular Thyroid Adenoma and Follicular Thyroid Carcinoma-A Common or Distinct Background? Loss of Heterozygosity in Comprehensive Microarray Study

Pre- and postsurgical differentiation between follicular thyroid adenoma (FTA) and follicular thyroid cancer (FTC) represents a significant diagnostic challenge. Furthermore, it remains unclear whether they share a common or distinct background and what the mechanisms underlying follicular thyroid lesions malignancy are. The study aimed to compare FTA and FTC by the comprehensive microarray and to identify recurrent regions of loss of heterozygosity (LOH). We analyzed formalin-fixed paraffin-embedded (FFPE) samples acquired from 32 Caucasian patients diagnosed with FTA (16) and FTC (16). We used the OncoScan™ microarray assay (Affymetrix, USA), using highly multiplexed molecular inversion probes for single nucleotide polymorphism (SNP). The total number of LOH was higher in FTC compared with FTA (18 vs. 15). The most common LOH present in 21 cases, in both FTA (10 cases) and FTC (11 cases), was 16p12.1, which encompasses many cancer-related genes, such as TP53, and was followed by 3p21.31. The only LOH present exclusively in FTA patients (56% vs. 0%) was 11p11.2-p11.12. The alteration which tended to be detected more often in FTC (6 vs. 1 in FTA) was 12q24.11-q24.13 overlapping FOXN4, MYL2, PTPN11 genes. FTA and FTC may share a common genetic background, even though differentiating rearrangements may also be detected.

Graves' disease and inflammatory bowel disease: A bidirectional Mendelian randomization

CONTEXT

Both Graves' disease (GD) and inflammatory bowel disease (IBD) are common autoimmune diseases that severely damage patients' quality of life. Previous epidemiological studies have suggested associations between GD and IBD. However, whether a causal relationship exists between these two diseases remains unknown.

OBJECTIVE

To infer a causal relationship between GD and IBD using bidirectional two-sample Mendelian randomization(MR).

METHODS

We performed bidirectional two-sample MR to infer a causal relationship between GD and IBD using GWAS summary data obtained from Biobank Japan (BBJ) and the International Inflammatory Bowel Disease Genetic Consortium (IIBDGC). Several methods (random-effect inverse variance weighted, weighted median, MR‒Egger regression, and MR-PRESSO) were used to ensure the robustness of the causal effect. Heterogeneity was measured based on Cochran's Q value. Horizontal pleiotropy was evaluated by MR‒Egger regression and leave-one-out analysis.

RESULTS

Genetically predicted IBD may increase the risk of GD by 24% (OR 1.24, 95% CI 1.01-1.52, p = 0.041). Crohn's disease (CD) may increase the risk of GD, whereas ulcerative colitis (UC) may prevent patients from developing GD. Conversely, genetically predicted GD may slightly increase the risk of CD, although evidence indicating that the presence of GD increased the risk of UC or IBD was lacking. Outlier-corrected results were consistent with raw causal estimates.

CONCLUSIONS

Our study revealed a potentially higher comorbidity rate for GD and CD. However, UC might represent a protective factor for GD. The underlying mechanism and potential common pathways await discovery.

The Whole Blood DNA Methylation Patterns of Extrinsic Apoptotic Signaling Pathway Related Genes in Autoimmune Thyroiditis among Areas with Different Iodine Levels

Autoimmune thyroiditis (AIT) has a complex etiology and the susceptibility to it is determined by a combination of genetic and environmental factors, although these are not yet fully understood. The present research aimed to explore the DNA methylation patterns in whole blood of extrinsic apoptotic signaling pathway related genes in AIT among areas with different iodine levels. We selected the iodine-fortification areas (IFA), iodine-adequate areas (IAA) and water-based iodine-excess areas (IEA) from Shandong Province of China as survey sites. Totally 176 AIT cases and 176 controls were included. MethylTargetTM and QT-PCR technology were used to detect candidate genes' DNA methylation levels and mRNA expression levels, respectively. We found that DAPK1 DNA methylation levels in AIT cases (especially in female) were significantly higher than controls (t=2.7715, P=0.0059; t=2.4638, P=0.0143 in female). There were differences in DAPK1(t=2.5384, P=0.0121), TNFSF8(t=2.1667, P=0.0334) and TNFAIP8(t=2.5672, P=0.0121) genes methylation between cases and controls with different water iodine levels. The mRNA expression of DAPK1(t=4.329, P<0.001) and TNFAIP8(t=3.775, P<0.001) in the cases were increased. We identified the differences in the DNA methylation status of the extrinsic apoptotic signaling pathway related genes between AIT and controls and in different iodine levels areas. The results were verified at the mRNA level. The environmental iodine may affect DNA methylation to some extent.

Biochemical genesis of enzymatic and non-enzymatic post-translational modifications

Post-translational modifications (PTMs) alter protein structure, function, and localization and play a pivotal role in physiological and pathophysiological conditions. Many PTMs arise from endogenous metabolic intermediates and serve as sensors for metabolic feedback to maintain cell growth and homeostasis. A key feature to PTMs is their biochemical genesis, which can result from either non-enzymatic adduction (nPTMs) or through enzyme-catalyzed reactions (ePTMs). The abundance and site-specificity of PTMs are determined by dedicated classes of enzymes that add (writers) or remove (erasers) the chemical addition. In this review we will highlight the biochemical genesis and regulation of a few of the 700+ PTMs that have been identified.

Insights Into the Role of DNA Methylation in Immune Cell Development and Autoimmune Disease

To date, nearly 100 autoimmune diseases have been an area of focus, and these diseases bring health challenges to approximately 5% of the population worldwide. As a type of disease caused by tolerance breakdown, both environmental and genetic risk factors contribute to autoimmune disease development. However, in most cases, there are still gaps in our understanding of disease pathogenesis, diagnosis, and treatment. Therefore, more detailed knowledge of disease pathogenesis and potential therapies is indispensable. DNA methylation, which does not affect the DNA sequence, is one of the key epigenetic silencing mechanisms and has been indicated to play a key role in gene expression regulation and to participate in the development of certain autoimmune diseases. Potential epigenetic regulation via DNA methylation has garnered more attention as a disease biomarker in recent years. In this review, we clarify the basic function and distribution of DNA methylation, evaluate its effects on gene expression and discuss related key enzymes. In addition, we summarize recent aberrant DNA methylation modifications identified in the most important cell types related to several autoimmune diseases and then provide potential directions for better diagnosing and monitoring disease progression driven by epigenetic control, which may broaden our understanding and contribute to further epigenetic research in autoimmune diseases.

Sex Dimorphic Responses of the Hypothalamus-Pituitary-Thyroid Axis to Energy Demands and Stress

The hypothalamus-pituitary-thyroid-axis (HPT) is one of the main neuroendocrine axes that control energy expenditure. The activity of hypophysiotropic thyrotropin releasing hormone (TRH) neurons is modulated by nutritional status, energy demands and stress, all of which are sex dependent. Sex dimorphism has been associated with sex steroids whose concentration vary along the life-span, but also to sex chromosomes that define not only sexual characteristics but the expression of relevant genes. In this review we describe sex differences in basal HPT axis activity and in its response to stress and to metabolic challenges in experimental animals at different stages of development, as well as some of the limited information available on humans. Literature review was accomplished by searching in Pubmed under the following words: "sex dimorphic" or "sex differences" or "female" or "women" and "thyrotropin" or "thyroid hormones" or "deiodinases" and "energy homeostasis" or "stress". The most representative articles were discussed, and to reduce the number of references, selected reviews were cited.

DNA hypermethylation of PTPN22 gene promoter in children and adolescents with Hashimoto thyroiditis

PURPOSE

Protein tyrosine phosphatase non-receptor type 22 (PTPN22) is an inhibitor of T-cell activation, regulating intracellular signal transduction and thereby being implicated in the pathogenesis of autoimmune thyroid disease (AITD). The exact molecular mechanisms have not been fully elucidated. The aim of the present study was to quantitate DNA methylation within the PTPN22 gene promoter in children and adolescents with AITD and healthy controls.

METHODS

60 Patients with Hashimoto thyroiditis (HT), 25 patients with HT and type 1 diabetes (HT + T1D), 9 patients with Graves' disease (GD) and 55 healthy controls without any individual or family history of autoimmune disease were enrolled. Whole blood DNA extraction, DNA modification using sodium bisulfate and quantification of DNA methylation in the PTPN22 gene promoter, based on melting curve analysis of the selected DNA fragment using a Real-Time PCR assay, were implemented.

RESULTS

DNA methylation in the PTPN22 gene promoter was found to be significantly higher in HT patients (39.9 ± 3.1%) in comparison with other study groups (20.3 ± 2.4% for HT + T1D, 32.6 ± 7.8% for GD, 27.1 ± 2.4% for controls, p < 0.001). PTPN22 gene promoter DNA methylation was also associated marginally with thyroid autoimmunity in general (p = 0.059), as well as considerably with thyroid volume (p = 0.004) and the presence of goiter (p = 0.001) but not thyroid function tests.

CONCLUSIONS

This study demonstrates for the first time that a relationship between autoimmune thyroiditis and PTPN22 gene promoter DNA methylation state is present, thus proposing another possible etiological association between thyroiditis and abnormalities of PTPN22 function. Further expression studies are required to confirm these findings.

Epigenetics effect on pathogenesis of thyroid-associated ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is an autoimmune disease. Recent studies have found the aberrant epigenetics in TAO, including DNA methylation, non-coding RNAs, and histone modification. Many genes have an aberrant level of methylation in TAO. For example, higher levels are found in CD14, MBP, ANGLE1, LYAR and lower levels in DRD4 and BOLL. Non-coding RNAs are involved in the immune response (miR-146a, miR-155, miR-96, miR-183), fibrosis regulation (miR-146a, miR-21, miR-29), adipogenesis (miR-27) and are thought to play roles in TAO. MicroRNA is also related to the clinical activity score (miR-Let7d-5p) and may be a predictor of glucocorticoid therapy (miR-224-5p). The quantities of H4 in TAO are increased compared with euthyroid control subjects, and the role of histone modifications in Graves' disease may lead to better understanding of its role in TAO. More studies are needed to explain the role of epigenetics in TAO and provide potential therapeutic strategies.

Graves' Disease and Rheumatoid Arthritis: A Bidirectional Mendelian Randomization Study

BACKGROUND

The frequent coexistence of Graves' disease (GD) and rheumatoid arthritis (RA) has been cited and discussed in observational studies, but it remains a question as to whether there is a causal effect between the two diseases.

METHODS

We retrieved genome-wide association study (GWAS) summary data of GD and RA from BioBank Japan (BBJ). Single nucleotide polymorphisms (SNPs) associated with diseases of interest were selected as instrumental variables (IVs) at a genome-wide significance level (P < 5.0 × 10^-8). The random-effects inverse variance weighted method (IVW) was used to combine the causal effect of IVs. The horizontal pleiotropy effect was analyzed by MR-Egger and weighted median method sensitivity test. A leave-one-out analysis was conducted to avoid bias caused by a single SNP. The statistical power of our MR result was calculated according to Brion's method.

RESULTS

Our study discovered a bidirectional causal effect between GD and RA. The presence of RA may increase the risk of GD by 39% (OR 1.39, 95% CI 1.10-1.75, P = 0.007). Similarly, the existence of GD may increase the risk of RA by 30% (OR 1.30, 95% CI 0.94-1.80, P = 0.112). Our study provides 100% power to detect the causal effect of RA on GD risk, and vice versa.

CONCLUSIONS

We found a bidirectional causal effect between GD and RA in an Asian population. Our study supported the clinical need for screening GD in RA patients, and vice versa. The potential benefit of sound management of RA in GD patients (or GD in RA patients) merits excellent attention. Moreover, novel satisfactory medicine for RA may be applicable to GD and such potential is worthy of further investigation.

Genotype association of IP6K3 gene with Hashimoto’s thyroiditis in Algerian population (Aures region)

Background

Hashimoto’s thyroiditis (HT) is a chronic autoimmune disease of the thyroid gland and is also the main cause of hypothyroidism. A recent genome-wide association study (GWAS) suggested an association of three novel genetic variants with HT in a population of Caucasian origin (Croatian). A case-control study was performed to investigate the association of these three newly suggested genetic variants with HT in a non-Caucasian ethnic group, an Arab-Berber from Algeria.

Three variants (rs12944194 located 206 kb from SDK2, rs791903 inside IP6K3, and rs75201096 inside GNA14) were genotyped using real-time PCR.

Results

There were no significant differences in allele frequencies of the three genetic variants between HT cases and controls. However, the present study showed nominal significance in the genotype distribution of rs791903 (IP6K3 gene) between HT patients and the control group (P = 0.024); we observed a decrease in the frequency of rs791903 recessive homozygotes (CC) in HT cases versus controls (OR = 0.476, P = 0.025).

Conclusion

This is the first study that showed the genotypic association of IP6K3 intronic variant with decreased risk for HT in non-Caucasian, Algerian, population, whereas we did not confirm the association of SDK2 and GNA14 genetic variants with HT. The IP6K3 gene (inositol hexaphosphate kinase 3), located near major histocompatibility complex (MHC), has previously been associated with other common autoimmune diseases beside HT, such as Graves’s disease and rheumatoid arthritis, which is providing more evidence of a good candidacy for the genetic contribution to the development of HT and autoimmunity.

Primary Microcephaly with Novel Variant of MCPH1 Gene in Twins: Both Manifesting in Childhood at the Same Time with Hashimoto's Thyroiditis

This study is a clinical report on twin females affected by primary microcephaly who displayed at molecular analysis of heterozygous novel MCPH1 variant. The twins at the age of 10 years developed, in coincidental time, a diagnosis of autoimmune juvenile thyroiditis. The main clinical features presented by the twins consisted of primary microcephaly with occipitofrontal circumference measuring -2 or -3 standard deviation, facial dysmorphism, typical nonsyndromic microcephaly, and mild intellectual disability. Molecular analysis of the major genes involved in primary microcephaly was performed and the following result was found in the twins: MCPH1 ; chr8.6357416; c.2180 C > T (rs 199861426), p.Pro727. Leu; heterozygous; missense; variant of uncertain significance (class 3). At the age of 10 years, the twins started to have, in coincidental time, marked asthenia and episodes of emotiveness, and laboratory exams disclosed a high level of antithyroid peroxidase leading to the diagnosis of autoimmune juvenile thyroiditis with normal thyroid function. The novel heterozygous MCPH1 variant found in the twins may be directly or indirectly involved in the onset of the primary microcephaly. The thyroid disorder in the twins and its onset, in a coincidental time, confirmed the effect of genetic predisposition on the pathogenesis of the immune thyroiditis.

Gene polymorphisms of VEGF and VEGFR2 are associated with the severity of Hashimoto's disease and the intractability of Graves' disease, respectively

Vascular endothelial growth factor (VEGF) is one of main regulators of angiogenesis that functions by binding to its receptors, including VEGF receptor (VEGFR) 2. There are few data available regarding the association between VEGF and VEGFR polymorphisms and the susceptibility to and prognosis of autoimmune thyroid diseases (AITDs). To elucidate this association, we genotyped four functional VEGF and two VEGFR2 polymorphisms and measured serum VEGF levels. In the four functional VEGF polymorphisms, the frequencies of the I carrier and I allele of VEGF -2549 I/D, which has lower activity, were higher in patients with severe HD than in those with mild HD. In the two functional VEGFR2 polymorphisms, the frequency of the rs2071559 CC genotype, which has higher activity, was higher in patients with intractable GD than in controls, and the proportion of GD patients with larger goiters was higher in those with the CC genotype. Moreover, the frequency of the rs1870377 TT genotype with higher activity was higher in patients with intractable GD than in those with GD in remission. Combinations of VEGF and VEGFR2 polymorphisms with stronger interactions were associated with the intractability of GD. Serum VEGF levels were higher in HD and AITD patients than those in controls. In conclusion, VEGF polymorphisms with lower activity were associated with the severity of HD, while VEGFR2 polymorphisms and the combinations of VEGF and VEGFR2 polymorphisms, which have stronger interactions, were associated with the intractability of GD. VEGF and VEGFR2 polymorphisms were associated with HD severity and GD intractability, respectively.

DNA methylation analysis within the IL2RA gene promoter in youth with autoimmune thyroid disease

BACKGROUND

Alpha-subunit of the interleukin-2 receptor (IL2RA) is involved in the regulation of T-cell function and has been related to autoimmune thyroid disease (AITD). Although the exact mechanisms are not fully understood, promoter methylation might account for differences in gene expression. The aim of this study was to investigate whether there are differences in the percentage of DNA methylation within the IL2RA gene promoter in young patients with AITD.

MATERIALS AND METHODS

In a cross-sectional design, the presence of DNA methylation in the IL2RA gene promoter was quantified, by real-time PCR and melting curve analysis, in modified genomic DNA isolated from blood samples of a total of 149 children and adolescents with AITD, including patients with Hashimoto thyroiditis (ΗΤ) (n = 60), Graves' disease (GD) (n = 9), concurrent diagnosis of HT and type 1 diabetes (T1DM + HT) (n = 25), and healthy controls (n = 55).

RESULTS

The percentage of DNA methylation in the IL2RA gene promoter was significantly decreased in patients with GD (26.0 ± 4.2%) but not in those with HT (36.3 ± 1.4%) in comparison with controls (41.3 ± 1.5%).

CONCLUSIONS

The observed DNA hypomethylation in the IL2RA gene promoter in patients with GD might be related to its increased expression, thus contributing to the etiopathogenesis of GD in childhood and adolescence.

Aberrant Histone Methylation in Patients with Graves' Disease

BACKGROUND

Graves' disease (GD) is an organ-specific autoimmune disease. Accumulated data have indicated that aberrant epigenetic modifications are associated with many autoimmune disorders. However, it remains unknown whether histone methylation plays a role in the pathogenesis of GD. In the present study, we aimed to assess histone modification patterns in peripheral blood mononuclear cells (PBMCs) from GD patients. The rate (degree) of H3K4 and H3K9 methylation and the expressions of histone-modifying genes were investigated.

METHODS

A total of 68 GD patients and 32 healthy controls were enrolled in this study. Global histone H3K4/H3K9 methylation of PBMCs was evaluated by the EpiQuik™ global histone H3K4/H3K9 methylation assay kit. The expressions of histone methyltransferases (HMTs) and histone demethylases (HDMs) at the mRNA level were determined by real-time quantitative polymerase chain reaction.

RESULTS

Global histone H3K9 methylation in PBMCs of GD patients was significantly decreased compared with that in the healthy controls (P=0.007). The expressions of HMTs (SUV39H1 and SUV39H2) at the mRNA level were significantly decreased in PBMCs from GD patients compared with healthy controls (P<0.001), whereas the SETD1A expression at the mRNA level was significantly increased in GD patients compared with healthy controls (P=0.004). In addition, the expressions of HDMs, including JHDM2A and JMJD2A, at the mRNA level were significantly increased in GD patients compared with healthy controls (P<0.001; P=0.007). Moreover, the mRNA expression levels of JARID1A and LSD1 did not significantly differ in GD patients and healthy controls (P>0.05).

CONCLUSIONS

These findings firstly suggested that the histone methylation was aberrant in PBMCs of GD patients, which could be possibly attributed to the deregulation of epigenetic modifier genes. Abnormal histone methylation modification may be involved in the pathogenesis of GD.

Insulin-like Growth Factor-I Receptor and Thyroid-Associated Ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is a complex disease process presumed to emerge from autoimmunity occurring in the thyroid gland, most frequently in Graves disease (GD). It is disfiguring and potentially blinding, culminating in orbital tissue remodeling and disruption of function of structures adjacent to the eye. There are currently no medical therapies proven capable of altering the clinical outcome of TAO in randomized, placebo-controlled multicenter trials. The orbital fibroblast represents the central target for immune reactivity. Recent identification of fibroblasts that putatively originate in the bone marrow as monocyte progenitors provides a plausible explanation for why antigens, the expressions of which were once considered restricted to the thyroid, are detected in the TAO orbit. These cells, known as fibrocytes, express relatively high levels of functional TSH receptor (TSHR) through which they can be activated by TSH and the GD-specific pathogenic antibodies that underpin thyroid overactivity. Fibrocytes also express insulin-like growth factor I receptor (IGF-IR) with which TSHR forms a physical and functional signaling complex. Notably, inhibition of IGF-IR activity results in the attenuation of signaling initiated at either receptor. Some studies suggest that IGF-IR-activating antibodies are generated in GD, whereas others refute this concept. These observations served as the rationale for implementing a recently completed therapeutic trial of teprotumumab, a monoclonal inhibitory antibody targeting IGF-IR in TAO. Results of that trial in active, moderate to severe disease revealed dramatic and rapid reductions in disease activity and severity. The targeting of IGF-IR with specific biologic agents may represent a paradigm shift in the therapy of TAO.

Phenotypic Expression of Autoimmunity in Children With Autoimmune Thyroid Disorders

Autoimmune thyroid diseases (AITDs), including Hashimoto's thyroiditis (HT) and Graves' disease (GD), tend to aggregate with other non-thyroidal autoimmune diseases (NTADs). Aim of this Mini-review is to report the most recent insights concerning the clustering of NTADs in pediatric patients with either HT or GD, the pathophysiology of AITDs and the metamorphic thyroid autoimmunity. A systematic literature research of the last 15 years, according to EQUATOR statement, was carried out through MEDLINE via PubMed (http://www.ncbi.nlm.nih.gov/pubmed/) Embase, CINAHL, Cochrane Library, based on the following keywords: (autoimmune thyroid disease OR Hashimoto thyroiditis OR Grave's disease) AND (autoimmune comorbidities OR extra-thyroidal autoimmune disorders) AND (children OR adolescents OR pediatrics) AND (celiac disease OR type 1 diabetes mellitus OR arthropathies OR cutaneous diseases) AND (Turner syndrome OR Down syndrome). One-hundred and twenty-eight manuscripts were extrapolated but only seventeen were eligible. On the basis of the available reports it may be inferred that clustering of NTADs can be significantly modified by both patients' age at AITDs presentation and association with Down's syndrome (DS). Particularly, the association of AITDs with celiac disease and type 1 diabetes was most commonly reported in children than in adults. A sequential shifting from HT to GD has been described in children with AITDs, and it seems to be more frequent in children with DS than in those without DS. Coexistence of autoimmune diseases might be the result of a complex interaction among genetics, environment and epigenetic modifications that are able to affect gene expression, immune system response and, finally, the pathogenesis of autoimmune diseases.

Graves' orbitopathy occurs sex-independently in an autoimmune hyperthyroid mouse model

Graves’ orbitopathy (GO) is the most common extra thyroidal complication of Graves’ disease (GD) and occurs predominantly in women but more severe in men. The reason for this effect of gender on GO is unknown. Herein we studied the manifestation of GO in both sexes of an induced mouse model in absence of additional risk factors present in patients like advanced age, genetic variabilities or smoking. Male and female mice were immunized with human TSHR A-subunit encoding plasmid. Both sexes comparably developed autoimmune hyperthyroidism characterized by TSHR stimulating autoantibodies, elevated T4 values, hyperplastic thyroids and hearts. Autoimmune mice developed inflammatory eye symptoms and proptosis, although males earlier than females. Serial in vivo¹H/¹⁹F-magnetic resonance imaging revealed elevated inflammatory infiltration, increased fat volume and glycosaminoglycan deposition in orbits of both sexes but most significantly in female mice. Histologically, infiltration of T-cells, extension of brown fat and overall collagen deposition were characteristics of GO in male mice. In contrast, female mice developed predominately macrophage infiltration in muscle and connective tissue, and muscle hypertrophy. Apart from sex-dependent variabilities in pathogenesis, disease classification revealed minor sex-differences in incidence and total outcome. In conclusion, sex does not predispose for autoimmune hyperthyroidism and associated GO.

Association between thyroglobulin polymorphisms and autoimmune thyroid disease: a systematic review and meta-analysis of case-control studies

Emerging evidence revealed that thyroglobulin (TG) contributes to the development of autoimmune disease, and the relationship between TG and autoimmune thyroid disease (AITD) is still controversial. The aim of this study was to quantify the association between rs2076740, rs853326, rs180223, and rs2069550 TG polymorphisms and risk of AITD using a meta-analysis approach. We identified all studies that assessed the association between TG polymorphisms and AITD from PubMed, Embase, and Web of Science databases. A total of 3013 cases and 1812 controls from ten case-control studies were included. There was no significant associations found between rs2069550, rs180223, and rs853326 polymorphisms and AITD risk. The association between the rs2076740 polymorphism and AITD risk was significant in the codominant model (P = 0.005), suggesting the CC rs2076740 genotype might be a protective factor for AITD. Sensitivity analysis by removing one or two study changed the results in dominant rs2076740 and rs853326 and rs2069550 allele models (P = 0.016, 0.024, 0.027). Latitude and ethnicity significantly affected the association between rs2076740 and rs2069550 polymorphisms and AITD, indicating their protective effects in allele or dominant model (P = 0.012, 0.012, 0.012, 0.009, 0.009). The association between rs2076740, rs2069550, and rs853326 polymorphisms and AITD risk is significantly affected by study characteristics.

Involvement of miR-126 in autoimmune disorders

BACKGROUND

Micro-RNA represent a great family of small non-condign ribonucleic acid molecules; in particular microRNA-126 is an important member of this family and is expressed in many human cells such as cardiomyocytes, endothelial and lung cells. Some studies have shown the implication of miR-126 in cancer, but recently significant progresses have also been made in determining the role of miR-126 regulating immune-related diseases; probably, in a near future, they could potentially serve as diagnostic biomarkers or therapeutic targets.

OBJECTIVE

The purpose of this review is to investigate the role of miR-126 in autoimmune diseases, so as to offer innovative therapies.

RESULTS

According literature, it was concluded that miRNAs, especially miR-126, are involved in many pathologies and that their expression levels increase in autoimmune diseases because they interfere with the transcription of the proteins involved. Since microRNAs can be detected from several biological sources, they may be attractive as potential biomarkers for the diagnosis, prognosis, disease activity and severity of various diseases. In fact, once confirmed the involvement of miR-126 in autoimmune diseases, it was speculated that it could be used as a promising biomarker. These discovers implicate that miR-126 have a central role in many pathways leading to the development and sustain of autoimmune diseases. Its key role make this microRNA a potential therapeutic target in autoimmunity.

CONCLUSION

Although miR-126 relevant role in several immune-related diseases, further studies are needed to clear its molecular mechanisms; the final step of these novel researches could be the blockage or the prevention of the diseases onset by creating of new targeted therapy.