T regulatory (Treg) and T helper 17 (Th17) lymphocytes in thyroid autoimmunity

l-Thyroxine does not prevent immunemediated sensorineural hearing loss in autoimmune thyroid diseases

OBJECTIVE

This is the first report dealing with immune-mediated inner ear disease (IMIED) hearing loss in a group of patients affected with autoimmune thyroid disease (AITD), whose treatment required corticosteroids, despite being treated with levothyroxine. Immunopathology linking the inner ear and the thyroid gland is also presented.

PATIENTS

A total of 220 patients were selected with sensorineural hearing loss (SNHL) of causes other than presbycusis. Audiometry was performed and pure tone average was calculated before and after treatment with corticosteroids.

RESULTS

Eighty-four (84) patients had SNHL of autoimmune origin, and 15 patients were diagnosed with AITD (Hashimoto's disease). Bilateral hearing loss was observed in 10 patients (66.5%). Sudden sensorineural hearing loss was the most frequent clinical form of presentation. Nine patients showed a hearing recovery greater than 10dB after corticosteroid treatment.

CONCLUSIONS

Acquired hypothyroidism is thought to affect hearing due to different mechanisms. Although specific hormonal therapy may improve peripheral or central auditory disorders associated with hypothyroidism, the presence of IMIED in AITD patients requires another approach. Altered immune regulatory mechanisms involving Treg cells and CD4+CD45RO cells have been suggested in patients with AITD and IMIED. In the present study, although all the patients with hypothyroidism and subclinical hypothyroidism were being treated with levothyroxine, immune-mediated hearing loss was observed. Therapy with corticosteroids could achieve hearing recovery. Since inner ear and thyroid gland share possible antigen targets, we highlight the existence of IMIED in AITD patients and the importance of implementing appropriate therapy with corticosteroids.

A MicroRNA Signature for Evaluation of Risk and Severity of Autoimmune Thyroid Diseases

CONTEXT

Circulating microRNAs (miRNAs) are emerging as an interesting research area because of their potential role as novel biomarkers and therapeutic targets. Their involvement in autoimmune thyroid diseases (AITDs) has not been fully explored.

OBJECTIVE

To compare the expression profile of miRNAs in thyroid tissue from patients with AITD and controls, using next-generation sequencing, further validated our findings in thyroid and serum samples.

DESIGN

Twenty fresh-frozen thyroid tissues (15 from patients with AITD and 5 from controls) were used for miRNA next-generation sequencing. Thirty-six thyroid samples were recruited for the qRT-PCR validation test and 58 serum samples for further validation in peripheral blood.

RESULTS

Expression of several miRNAs that had been previously associated with relevant immunological functions was significantly dysregulated. Specifically, eight differentially expressed miRNAs (miR-21-5p, miR-142-3p, miR-146a-5p, miR-146b-5p, miR-155-5p, miR-338-5p, miR-342-5p, and miR-766-3p) were confirmed using qRT-PCR in thyroid samples, and three had the same behavior in tissue and serum samples (miR-21-5p, miR-142-3p, and miR-146a-5p). Furthermore, when the expression of these miRNAs was assessed together with five additional ones previously related to AITD in peripheral blood, the expression of five (miR-Let7d-5p, miR-21-5p, miR-96-5p, miR-142-3p, and miR-301a-3p) was significantly expressed in AITD and, in patients with Graves disease (GD), was correlated with a higher severity of disease, including active ophthalmopathy, goiter, higher antibody titers, and/or higher recurrence rates.

CONCLUSIONS

The present findings identify a serum five-signature miRNA that could be an independent risk factor for developing AITD and a predisposition of a worse clinical picture in patients with GD.

Estrogen receptor β activation stimulates the development of experimental autoimmune thyroiditis through up-regulation of Th17-type responses

Estrogens play important roles in autoimmune thyroiditis, but it remains unknown which estrogen receptor (ER) subtype mediates the stimulatory effects. Herein we treated ovariectomized mice with ERα or ERβ selective agonist followed by thyroglobulin-immunization to induce experimental autoimmune thyroiditis (EAT), and observed the aggravation of EAT after diarylpropionitrile (DPN, ERβ selective agonist) administration. The mRNA levels of interleukin(IL)-17A, IL-21 and RORγt and percentages of T helper (Th) 17 cells were up-regulated in the splenocytes of DPN-treated mice. Activated ERβ was found directly binding to IL-17A and IL-21 gene promoters, and also indirectly promoting IL-21 and RORγt gene transcription through interaction with NF-κB. The expressions of co-stimulatory molecules were increased on antigen-presenting cells (APCs) after DPN administration. It suggests that ERβ is the predominant ER subtype responsible for EAT development, and its activation may enhance Th17-type responses through genomic pathways and alteration of APCs' activities.

Role of the T and B lymphocytes in pathogenesis of autoimmune thyroid diseases

Autoimmune thyroid disorders (AITD) broadly include Graves' disease and Hashimoto's thyroiditis which are the most common causes of thyroid gland dysfunctions. These disorders develop due to complex interactions between environmental and genetic factors and are characterized by reactivity to self-thyroid antigens due to autoreactive lymphocytes escaping tolerance. Both cell-mediated and humoral responses lead to tissue injury in autoimmune thyroid disease. The differentiation of CD4+ cells in the specific setting of immune mediators (for example cytokines, chemokines) results in differentiation of various T cell subsets. T cell identification has shown a mixed pattern of cytokine production indicating that both subtypes of T helper, Th1 and Th2, responses are involved in all types of AITD. Furthermore, recent studies described T cell subtypes Th17 and Treg which also play an essential role in pathogenesis of AITD. This review will focus on the role of the T regulatory (Treg) and T helper (Th) (especially Th17) lymphocytes, and also of B lymphocytes in AITD pathogenesis. However, we have much more to learn about cellular mechanisms and interactions in AITD before we can develop complete understanding of AITD pathophysiology.

Hypophysitis following Treatment with Ustekinumab: Radiological and Pathological Findings

CONTEXT

Ustekinumab is a human IgG1 monoclonal antibody that targets interleukin (IL)-12 and IL-23, which may be useful in the treatment of autoimmune conditions such as psoriasis, psoriatic arthritis, and Crohn's disease. Hypophysitis is an immune-derived inflammatory condition of the pituitary gland that may lead to pituitary dysfunction. With the increasing use of immunotherapy, it is possible that this and other new immune-related adverse events (IRAEs) arise, although the mechanisms involved are still incompletely defined.

CASE DESCRIPTION

A 35-year-old male, with a previous history of severe plaque-psoriasis who had started treatment with ustekinumab 4 months before, complained of progressive and persistent headache. Brain magnetic resonance imaging (MRI) was unremarkable. One year later, a new MRI was performed due to headache persistence, which revealed a homogenous and diffuse pituitary enlargement, with suprasellar extension and optic chiasm involvement, blurring of the pituitary stalk, absence of clear differentiation between the anterior and posterior lobes, and no signs of hemorrhage or adenomas. Endocrine evaluation was consistent with panhypopituitarism. Work-up of infiltrative and infectious diseases was negative. Follow-up MRI revealed an increase in the pituitary enlargement and transsphenoidal surgery was performed. Pathological findings revealed an intense fibrosis and a chronic inflammatory infiltrate, but no evidence of adenoma, granuloma, or acid fast bacilli. Immunohistochemical staining showed a combined T-cell (CD3+, CD4+) and B-cell (CD19+, CD20+) phenotype.

CONCLUSION

We suggest a novel IRAE of ustekinumab, with full radiological and immunopathological iconography, which may be mediated by the complex interaction between different immunological processes.

Oral exposure to dibutyl phthalate exacerbates chronic lymphocytic thyroiditis through oxidative stress in female Wistar rats

Chronic lymphocytic thyroiditis (CLT) is a common autoimmune disorder. The possible pathogenic role and mechanism of dibutyl phthalate (DBP) in CLT is still controversial. Experiments were conducted after 35-days of oral exposure to the three concentrations of DBP or saline, and three immunizations with thyroglobulin (TG). Healthy female Wistar rats were randomly divided into ten exposure groups (n = 8 each): (A) saline control, (B) 0.5 mg/kg/d DBP, (C) 5 mg/kg/d DBP, (D) 50 mg/kg/d DBP, (E) TG-immunized group, (F) TG- combined with 0.5 mg/kg/d DBP, (G) TG- combined with 5 mg/kg/d DBP, (H) TG- combined with 50 mg/kg/d DBP, (I) TG- combined with 50 mg/kg/d DBP plus 100 mg/kg/d vitamin C; (J) 100 mg/kg/d vitamin C. We showed that oral exposure DBP can aggravate CLT in rats. This deterioration was concomitant with increased thyroid auto antibodies, Th1/Th2 imbalance and Th17 immune response, activated pro-inflammatory and apoptosis pathways, and increased thyroid dysfunction in rats. Our results also suggested that DBP could promote oxidative damage. The study also found that vitamin C reduced the levels of oxidative stress and alleviated CLT. In short, the study showed that DBP exacerbated CLT through oxidative stress.

Recent advances in understanding autoimmune thyroid disease: the tallest tree in the forest of polyautoimmunity

Autoimmune thyroid disease (AITD) is often observed together with other autoimmune diseases. The coexistence of two or more autoimmune diseases in the same patient is referred to as polyautoimmunity, and AITD is the autoimmune disease most frequently involved. The occurrence of polyautoimmunity has led to the hypothesis that the affected patients suffer from a generalized dysregulation of their immune system. The present review summarizes recent discoveries unravelling the immunological mechanisms involved in autoimmunity, ranging from natural autoimmunity to disease-specific autoimmunity. Furthermore, the clinical grounds for considering AITD in a setting of polyautoimmunity are explored. A better understanding of these may pave the way for designing new treatment modalities targeting the underlying immune dysregulation when AITD appears in the context of polyautoimmunity.

Patients with Systemic Lupus Erythematosus Show Increased Levels and Defective Function of CD69+ T Regulatory Cells

T regulatory (Treg) cells have a key role in the pathogenesis of chronic inflammatory and autoimmune diseases. A CD4⁺CD69⁺ T cell subset has been described that behaves as Treg lymphocytes, exerting an important immune suppressive effect. In this study, we analyzed the levels and function of CD4⁺CD69⁺ Treg cells in patients with systemic lupus erythematosus (SLE). Blood samples were obtained from 22 patients with SLE and 25 healthy subjects. Levels of CD4⁺CD69⁺ Treg cells were analyzed by multiparametric flow cytometry, and their function was measured by an assay of suppression of lymphocyte activation and through the inhibition of cytokine synthesis. We found an increased percent of CD4⁺CD25^varCD69⁺TGF-β⁺IL-10⁺Foxp3⁻ lymphocytes in patients with SLE compared to controls. In addition, a significant diminution in the suppressive effect of these cells on the activation of autologous T lymphocytes was observed in most patients with SLE. Accordingly, CD69⁺ Treg cells from SLE patients showed a defective capability to inhibit the release of IL-2, IL-6, IL-10, and IL-17A by autologous lymphocytes. Our findings suggest that while CD4⁺CD69⁺ Treg lymphocyte levels are increased in SLE patients, these cells are apparently unable to contribute to the downmodulation of the autoimmune response and the tissue damage seen in this condition.

Pathogenic Th17 and Th22 cells are increased in patients with autoimmune thyroid disorders

PURPOSE

To study the levels of pathogenic and non-pathogenic Th17 and Th22 cells in autoimmune thyroid disorders patients. Although Th17 cells seem to play an important role in the pathogenesis of thyroid autoimmune disorders, the specific subsets of these lymphocytes have not been analyzed in this condition.

METHODS

We assessed the levels of Th17 (pathogenic and non-pathogenic) and Th22 cells in peripheral blood and thyroid glands of autoimmune thyroid disorders patients (n   =  26, 16 with Graves' disease and 10 with Hashimoto's thyroiditis) and 15 healthy controls by multi-parametric flow cytometry and immunofluorescence microscopy.

RESULTS

We found increased levels of pathogenic Th17 lymphocytes and Th22 cells in peripheral blood from autoimmune thyroid disorders patients. In addition, these cells were detected in thyroid glands from HT patients. Furthermore, we found significant correlations between the levels of these cells and disease activity, disease duration, and the presence of ophthalmopathy.

CONCLUSIONS

The increased levels of pathogenic Th17 lymphocytes and Th22 cells in autoimmune thyroid disorders suggest their involvement in the pathogenesis of this condition.

Imbalances in T Cell-Related Transcription Factors Among Patients with Hashimoto's Thyroiditis

OBJECTIVES

Imbalances in effector T cell functioning have been associated with a number of autoimmune diseases, including Hashimoto's thyroiditis (HT). Differentiation of effector T helper (Th) 1, Th2, Th17 and regulatory T cell (Treg) lymphocytes is regulated by transcription factors, including Th1-specific T box (T-bet), GATA binding protein-3 (GATA₃), retinoid-related orphan receptor (ROR)-α and forkhead box P3 (FOXP3). This study aimed to investigate Th1/Th2, Th1/Treg, Th2/Treg and Th17/Treg balances at the level of these transcription factors.

METHODS

This study took place between October 2015 and August 2016. Peripheral blood mononuclear cells were collected from a control group of 40 healthy women recruited from the Zahedan University of Medical Sciences, Zahedan, Iran, and a patient group of 40 women with HT referred to the Hazrat Ali Asghar Hospital, Zahedan. Total ribonucleic acid extraction was performed and the gene expression of transcription factors was quantitated using a real-time polymerase chain reaction technique.

RESULTS

Expression of T-bet and GATA₃ was significantly elevated, while FOXP3 expression was significantly diminished among HT patients in comparison with the controls (P = 0.03, 0.01 and 0.05, respectively). Expression of RORα was higher among HT patients, although this difference was not significant (P = 0.15). Expression of T-bet/FOXP3, GATA₃/FOXP3 and RORα/FOXP3 ratios were increased among HT patients in comparison with the controls (P <0.02, <0.01 and <0.01, respectively).

CONCLUSION

These results indicate that HT patients have imbalances in Th1/Treg, Th2/Treg and Th17/Treg lymphocytes at the level of the transcription factors, deviating towards Th1, Th2 and Th17 cells. Correction of these imbalances may therefore be therapeutic.

Autoimmune thyroid diseases in children

Autoimmune thyroid diseases (AIT) are common in children and may present with a variety of signs and symptoms including: euthyroid goiter, hypothyroidism, or hyperthyroidism. The natural history of AIT may be different in children but in all age groups, there appear to be genetic risk factors and environmental triggers that initiate thyroid autoimmunity. Areas covered: In this review, we summarize recent studies that investigate the genetics and environmental triggers believed to be involved in thyroid autoimmunity. We also discuss the approach and controversies in the treatment of children with AIT. Expert commentary: Much has been learned about the major roles for genetics, cytokines, regulatory lymphocytes, and environmental triggers in CLT but controversies remain.

Recovery responses of testosterone, growth hormone, and IGF-1 after resistance exercise

The complexity and redundancy of the endocrine pathways during recovery related to anabolic function in the body belie an oversimplistic approach to its study. The purpose of this review is to examine the role of resistance exercise (RE) on the recovery responses of three major anabolic hormones, testosterone, growth hormone(s), and insulin-like growth factor 1. Each hormone has a complexity related to differential pathways of action as well as interactions with binding proteins and receptor interactions. Testosterone is the primary anabolic hormone, and its concentration changes during the recovery period depending on the upregulation or downregulation of the androgen receptor. Multiple tissues beyond skeletal muscle are targeted under hormonal control and play critical roles in metabolism and physiological function. Growth hormone (GH) demonstrates differential increases in recovery with RE based on the type of GH being assayed and workout being used. IGF-1 shows variable increases in recovery with RE and is intimately linked to a host of binding proteins that are essential to its integrative actions and mediating targeting effects. The RE stress is related to recruitment of muscle tissue with the glandular release of hormones as signals to target tissues to support homeostatic mechanisms for metabolism and tissue repair during the recovery process. Anabolic hormones play a crucial role in the body’s response to metabolism, repair, and adaptive capabilities especially in response to anabolic-type RE. Changes of these hormones following RE during recovery in the circulatory biocompartment of blood are reflective of the many mechanisms of action that are in play in the repair and recovery process.

Expression and Function of the Costimulatory Receptor SLAMF1 Is Altered in Lymphocytes From Patients With Autoimmune Thyroiditis

CONTEXT

Signaling lymphocytic activation molecule family 1 (SLAMF1) is a costimulatory receptor expressed by most immune cells. Its role in autoimmune thyroid disease (AITD) is not well known.

OBJECTIVE

To analyze the expression and function of the costimulatory receptor SLAMF1 in lymphocytes of patients with AITD.

DESIGN

Cross-sectional, prospective, single-center study.

SETTING

Department of Endocrinology, Hospital Universitario de la Princesa, Madrid.

PATIENTS

Twenty-eight patients with AITD (17 with Graves disease and 11 with Hashimoto thyroiditis) and 21 controls.

INTERVENTION

Multiparametric flow cytometry and immunofluorescence techniques to analyze the expression of SLAMF1 in peripheral blood (n = 28) and thyroid tissue (n = 5) mononuclear cells. Assay of inhibition of cellular proliferation to study the function of SLAMF1 in CD4+CD25+ T regulatory (Treg) cells.

MAIN OUTCOME MEASURE

Expression levels and the function of SLAMF1 in lymphocytes in AITD patients and controls.

RESULTS

Expression of SLAMF1 was significantly increased in peripheral blood CD4+, T helper 17, and CD19+ B cells from AITD patients. Immunofluorescence microscopy detected the presence of SLAMF1+ lymphocytes in thyroid inflammatory cell infiltrate. Functional studies showed that SLAMF1 engagement in Treg cells increased their suppressive function in healthy controls but not in AITD patients.

CONCLUSIONS

The altered expression of SLAMF1, as well as its defective function observed in patients with AITD, may have a relevant role in the defective immune-regulatory function observed in this condition.

Graves' Disease in Pediatric and Elderly Patients with 22q11.2 Deletion Syndrome

22q11.2 Deletion Syndrome (22qDS) is often complicated by autoimmune diseases. To clarify the causal relationship, we examined the lymphocyte subset distribution and the human leucocyte antigen (HLA) in two female patients (one child and an elderly) with Graves' disease (GD) and 22qDS. Thymus dysgenesis might have contributed to the T-cell imbalance and the lack of negative selection in both cases. Notably, HLA-DR14, a known risk factor for GD in Japanese individuals and the decreased regulatory T-cell numbers that were seen in the pediatric case, may affect the early onset of GD. Central and peripheral tolerance and Th1 cells appeared to be associated with the pathogenesis of GD in 22qDS.

The Expression of T Cell FOXP3 and T-Bet Is Upregulated in Severe but Not Euthyroid Hashimoto's Thyroiditis

Hashimoto's thyroiditis (HT) is an organ-specific autoimmune disorder characterized by progressive thyroid failure. Th1 and Treg subset of CD4⁺ cells have been implicated in the pathogenesis; however, less is known about their respective roles across the spectrum of HT clinical presentations. To shed more light on CD4⁺ subsets role in HT, we investigated the mRNA expression levels of several Th1/Treg-associated transcription factors (T-bet/ETS1, HIF1α/BLIMP1/FOXP3) in peripheral blood T cells of 10 hypothyroid, untreated HT patients, 10 hypothyroid patients undergoing hormone replacement therapy, 12 euthyroid HT subjects, and 11 healthy controls by the qRT-PCR. Compared to euthyroid HT patients and controls, both hypothyroid (2.34-fold difference versus controls, P < 0.01) and thyroxine-supplemented patients (2.5-fold, P < 0.001) showed an increased FOXP3 mRNA expression in T cells. Similarly, mRNA expression levels of T-bet were upregulated in severely affected but not in euthyroid HT subjects (2.37-fold and 3.2-fold, hypothyroid and thyroxine-supplemented HT patients versus controls, resp., P < 0.01). By contrast, no differences in mRNA expression levels of ETS1, BLIMP1, and HIF1α were observed across the study groups. In summary, severe but not euthyroid HT was associated with robust upregulation of T-bet and FOXP3 mRNA in peripheral T cells, independent of the thyroid hormone status but proportional to disease activity.

Impaired immune regulation after radioiodine therapy for Graves' disease and the protective effect of Methimazole

Both therapies for Graves' disease (GD), radioactive iodine (RAI) and antithyroid drugs (ATD), were reported to have specific immune effects. We aimed at investigating the effects of RAI therapy on cellular subsets involved in immune regulation. We conducted a thirty day follow-up prospective cohort study of adult patients. Patients eligible for RAI therapy at our centre were approached. Twenty seven patients with GD were recruited, among whom 11 were treated with ATD. Twenty-two healthy subjects (HS) were also studied. Over time, frequency of regulatory T cells (Treg) and of invariant natural killer T cells (iNKT), along with Treg cell-mediated suppression and underlying mechanisms, were monitored in the peripheral blood. Variance in frequency of Treg and iNKT after RAI therapy was higher in GD patients than in HS over time (p < 0.0001). Reduced Treg suppressive function was observed after RAI therapy in GD patients (p = 0.002). ATD medication prior to RAI dampened these outcomes: less variation of Treg frequency (p = 0.0394), a trend toward less impaired Treg function, and prevention of reduced levels of suppressive cytokines (p < 0.05). Shortly after RAI therapy, alterations in immunoregulatory cells in patients with GD were observed and partially prevented by an ATD pretreatment. Worsening of autoimmunity after RAI was explained in previous studies by enhanced immune activity. This study adds new highlights on immune regulation deficiencies after therapeutic interventions in thyroid autoimmunity.

Decreased proportions of CD4 + IL17+/CD4 + CD25 + CD127- and CD4 + IL17+/CD4 + CD25 + CD127 - FoxP3+ T cells in children with autoimmune thyroid diseases (.)

Until now, altered balance of Th1 and Th2 immune cells has been postulated to play an important role in the pathogenesis of autoimmune thyroid diseases (AITD). However, recent studies on thyroid diseases have suggested a new role for Th17 cells that have been classified as a new lineage, distinct from Th1, Th2 and Treg cells. Despite wide interest, the role of Th17 cells in the pathogenesis of inflammatory and autoimmune diseases is still debated. The aim of the study was to estimate the proportions of Th17/Treg T cells in peripheral blood from patients with Graves' disease (GD; n = 29, mean age 15.4 ± 5.1 years), Hashimoto's thyroiditis (HT; n = 39, mean age 15.2 ± 4.1 years) and in healthy controls (n = 49, mean age 14.8 ± 3 years). Polychromatic flow cytometry and several fluorochrome-conjugated monoclonal antibodies were applied to delineate Th17 and Treg cells. The analysis of Th17/Treg T cell proportions in peripheral blood from patients with Graves' disease revealed significantly lower ratios of CD4 + IL17+/CD4 + CD25 + CD127 - (p < 0.0021) and CD4 + IL17+/CD4 + CD25 + CD127 - FoxP3 + (p < 0.0031) than in the control group. In addition, in the case of HT, we observed a significant decrease in the ratios of CD4 + IL17+/CD4 + CD25 + CD127 - (p < 0.0001) and CD4 + IL17+/CD4 + CD25 + CD127 - FoxP3 + (p < 0.0001) T cells in comparison to healthy children. In patients with untreated GD, a statistically significant positive correlation was found between the proportions of CD4 + IL17+/CD4 + CD25 + CD127-, CD4 + IL17+/CD4 + CD25 + CD127 - FoxP3+ T cells and the TRAbs (R = 0.71, p < 0.029; R = 0.72, p < 0.026, respectively) and a positive correlation was noted between the percentage of CD4 + CD - IL - 17 + T cells and the level of TSAbs (R = 0.66, p < 0.037). We conclude that the changes in the proportion of Th17/Treg T cells in peripheral blood and their significant relationship with the level of anti-thyroid antibodies indicate an involvement of these cells in the pathogenesis of AITD.

Thyrotropin Receptor Epitope and Human Leukocyte Antigen in Graves' Disease

Graves' disease (GD) is an organ-specific autoimmune disease, and thyrotropin (TSH) receptor (TSHR) is a major autoantigen in this condition. Since the extracellular domain of human TSHR (TSHR-ECD) is shed into the circulation, TSHR-ECD is a preferentially immunogenic portion of TSHR. Both genetic factors and environmental factors contribute to development of GD. Inheritance of human leukocyte antigen (HLA) genes, especially HLA-DR3, is associated with GD. TSHR-ECD protein is endocytosed into antigen-presenting cells (APCs), and processed to TSHR-ECD peptides. These peptide epitopes bind to HLA-class II molecules, and subsequently the complex of HLA-class II and TSHR-ECD epitope is presented to CD4+ T cells. The activated CD4+ T cells secrete cytokines/chemokines that stimulate B-cells to produce TSAb, and in turn hyperthyroidism occurs. Numerous studies have been done to identify T- and B-cell epitopes in TSHR-ECD, including (1) in silico, (2) in vitro, (3) in vivo, and (4) clinical experiments. Murine models of GD and HLA-transgenic mice have played a pivotal role in elucidating the immunological mechanisms. To date, linear or conformational epitopes of TSHR-ECD, as well as the molecular structure of the epitope-binding groove in HLA-DR, were reported to be related to the pathogenesis in GD. Dysfunction of central tolerance in the thymus, or in peripheral tolerance, such as regulatory T cells, could allow development of GD. Novel treatments using TSHR antagonists or mutated TSHR peptides have been reported to be effective. We review and update the role of immunogenic TSHR epitopes and HLA in GD, and offer perspectives on TSHR epitope specific treatments.