The interaction of TSH receptor autoantibodies with 125I-labelled TSH receptor

Long-term Effect of Thyrotropin-binding Inhibitor Immunoglobulin on Atrial Fibrillation in Euthyroid Patients

OBJECTIVE

Individuals with hyperthyroidism are at an increased risk of atrial fibrillation (AF), but the association between autoantibodies and AF or cardiovascular mortality in individuals who have returned to normal thyroid function remains unclear.

METHODS

The study utilized electronic medical records from National Taiwan University Hospital between 2000 and 2022. Each hyperthyroidism patient had at least 1 thyrotropin-binding inhibiting immunoglobulin (TBII) measurement. The relationship between TBII levels and the risk of AF and cardiovascular mortality was assessed using multivariable Cox regression models and Kaplan-Meier survival analysis.

RESULTS

Among the 14 618 enrolled patients over a 20-year timeframe, 173 individuals developed AF, while 46 experienced cardiovascular mortality. TBII values exceeding 35% were significantly associated with an elevated risk of AF for both the first TBII (hazard ratio {HR} 1.48 [1.05-2.08], P = .027) and mean TBII (HR 1.91 [1.37-2.65], P < .001). Furthermore, after free T4 levels had normalized, a borderline association between first TBII and AF (HR 1.59 [0.99-2.56], P = .056) was observed, while higher mean TBII increased AF (HR 1.78 [1.11-2.85], P = .017). Higher first and mean TBII burden continued to significantly impact the incidence of cardiovascular mortality (HR 6.73 [1.42-31.82], P = .016; 7.87 [1.66-37.20], P = .009). Kaplan-Meier analysis demonstrated that elevated TBII levels increased the risk of AF and cardiac mortality (log-rank P = .035 and .027, respectively).

CONCLUSION

In euthyroid individuals following antithyroid treatment, elevated circulating TBII levels and burden are associated with an elevated risk of long-term incident AF and cardiovascular mortality. Further reduction of TBII level below 35% will benefit to clinical outcomes.

Associations of serum keratin 1 with thyroid function and immunity in Graves' disease

BACKGROUND

Autoimmune thyroid disease (AITD) can cause enormous health burdens; however, trustworthy biomarkers in identifying the onset and progression of AITD are limited. In this study, we attempted to discover new potential serum biomarkers to discriminate AITD using mass spectrometry (MS).

METHODS

In the biomarker study cohort, 20 patients with Graves' disease (GD), 20 patients with Hashimoto's thyroiditis (HT), and 20 healthy controls were enrolled for a liquid chromatographic-tandem MS assessment. A novel biomarker, keratin 1 (KRT1), was selected for further evaluation in the validation cohort, including 125 patients with GD, 34 patients with HT, and 77 controls. Relationships of serum KRT1 with AITD-related immunomodulatory cytokines were also analyzed using enzyme-linked immunosorbent assays (ELISAs).

RESULTS

In the MS analysis, KRT1 was the single marker overexpressed in GD, while it was underexpressed in HT. In the ELISA analysis of the validation cohort, KRT1 was consistently upregulated in GD, while it was not downregulated in HT. There were significant associations of KRT1 levels with thyroid function in GD, AITD, and overall subjects. Additionally, a significant association of KRT1 levels with thyroid-stimulating hormone receptor antibody (TSHRAb) levels was observed. Moreover, there were significant associations of KRT1 with osteopontin (OPN) and B-cell activating factor (BAFF) levels in GD.

CONCLUSIONS

Serum KRT1 levels were upregulated in GD and were associated with thyroid function and TSHRAb levels. Moreover, KRT1 was correlated with the BAFF and OPN levels in GD patients. Further molecular-based research to elucidate the role of KRT1 in the pathogenesis of AITD is needed.

The pathogenic role of IFN-α in thyroiditis mouse models

AIM

Patients with chronic hepatitis C are frequently treated with interferon (IFN)-α. Autoimmune thyroid disease occurs in 20% ~ 40% of IFN-α-treated patients. In this study, the effects of IFN-α administration on triggering and regulating autoimmune thyroiditis in various animal models were evaluated.

MAIN METHODS

Exogenous IFN-α was given to naive CBA mice, and both thyroglobulin (TG) immunization-induced (CBA) and spontaneous autoimmune thyroiditis (NOD·H-2 h4) models. Thyroid function, and anti-thyroglobulin antibody (ATA) and B-cell-activating factor (BAFF) levels were measured. Alterations in transcriptome profiles were analyzed.

KEY FINDINGS

In the TG-induced thyroiditis model, IFN-α administration reduced plasma free thyroxine levels but did not alter ATA titers, BAFF levels, or the severity of histological changes. Interestingly, even without changes in thyroid functions, four of eight mice in the IFN-α alone group exhibited thyroiditis compared to the control group. Immunologically, mice in the IFN-α group exhibited profound CD3⁺ cell infiltration in the thyroid and higher plasma BAFF levels compared to the control group. Meanwhile, pathological and serological alterations after IFN-α administration were not observed in the NOD·H-2 h4 model. An RNA sequencing analysis revealed that immunoregulatory signatures were not excited by IFN-α treatment in naive CBA mice. Meanwhile, innate and adaptive immunity, inflammatory cytokine, chemokine, and cell-killing signaling pathways were all stimulated by IFN-α administration after TG immunization of CBA mice.

SIGNIFICANCE

We confirmed the remarkable effects of IFN-α in both initiating thyroid immunity and modulating thyroid function and immunoregulatory signatures in established autoimmune thyroiditis. We suggest that IFN-α should be administered with caution in clinical settings.

Possible interplay between estrogen and the BAFF may modify thyroid activity in Graves' disease

A link between sex hormones and B-cell activating factor (BAFF), a crucial immunoregulator of autoimmune thyroid disease (AITD), may exist. The study aimed to elucidate the role of estrogen (E2) in regulating BAFF in Graves' disease (GD). In clinical samples, serum BAFF levels were higher in women than in men in both the GD and control groups. serum BAFF levels were associated with thyroid-stimulating hormone receptor antibody levels and thyroid function only in women and not in men. BAFF transcripts in peripheral blood mononuclear cells were higher in women with GD than those in the control group. Among GD patients with the AA genotype of rs2893321, women had higher BAFF transcripts and protein levels than men. In the progression of a spontaneous autoimmune thyroiditis (SAT) murine model, NOD.H-2h4, serum free thyroxine and BAFF levels were higher in female than in male mice. Moreover, exogenous E2 treatment increased serum BAFF levels in male SAT mice. Meanwhile, female SAT mice exhibited higher thyroid BAFF transcripts levels than either the E2-treated or untreated male SAT mouse groups. Our results showed that E2 might be implicated in modulating BAFF expression, and support a possible mechanism for the higher incidence of AITD in women.

Third generation radioimmunoassay (RIA) for TSH receptor autoantibodies (TRAb) - one step less, similar results?

Aim  TSH-receptor (TSHR)-autoantibody (TRAb) is the serological hallmark of Graves’ disease (GD). Recently, 3 ^rd -generation radioimmunoassays (RIA) employing monoclonal TRAb such as M22 or T7 instead of TSH for the inhibition of human TRAb binding with solid-phase TSHR (coated tubes) have been introduced into laboratory routine.

Methods  As current assays typically employ a consecutive incubation of patient serum and labelled monoclonal TRAb, automation of TRAb RIA is a challenge. Thus, the assay procedure using human TSHR-coated tubes and the mouse monoclonal TRAb T7 was modified by combining both steps. The novel one-step method was compared with its corresponding consecutive 3 ^rd -generation RIA by investigating 304 individuals encompassing 102 patients with active GD (GD _a ), 43 patients with GD after successful therapy (GD _t ), 31 with Hashimoto’s disease (HD), 28 with non-autoimmune thyroid diseases (NAITD) and 100 healthy subjects (HS).

Results  With the new method, the incubation time was shortened by approximately one hour. Both 3 ^rd -generation RIAs did not reveal a significantly different assay performance by comparing areas under the curve (AUC) with receiver operating characteristics curve analysis (AUC one-step: 0.94, AUC two-step: 0.96, p > 0.05, respectively). The two-step TRAb RIA demonstrated sensitivity and specificity values of 87.5 % and 96.2 %, respectively, whereas the one-step revealed 84.6 % and 96.2 %, respectively.

Conclusion  One-step 3 ^rd -generation RIA may be used for the reliable detection of TRAb. The shorter and easier assay design may improve its use and enable automation in routine nuclear medicine laboratories.

Serum interferon levels associated with the disease activity in women with overt Graves' disease

BACKGROUND

Inflammatory cytokines participate in immune reactions and the pathogenesis of autoimmunity. Herein, we quantified four groups of inflammatory cytokines, including interferons (IFNs), the tumor necrosis factor (TNF) superfamily (TNFSF), interleukin (IL)-related cytokines, and bone and extracellular matrix remodeling-related cytokines to determine their contributions in women with overt Graves' disease (GD).

METHODS

Forty-three women with GD were enrolled in this cross-sectional study. Thirty-seven cytokines, thyroid-stimulating hormone (TSH), free thyroxine, and TSH receptor antibody (TSHRAb) were quantified. GD patients with a low TSH level at the time of sample collection were defined as having active GD.

RESULTS

Patients with active GD had higher IFN-α2, IFN-γ, IFN-λ1, and IFN-λ2 levels than those with inactive GD. In addition, certain TNFSF cytokines, including soluble cluster of differentiation 30 (sCD30), TNFSF member 14 (TNFSF14), pentraxin (PTX)-3, soluble TNF receptor 2 (sTNF-R2), and thymic stromal lymphopoietin (TSLP) were higher in active GD than in inactive GD. Moreover, active GD patients had higher IL-2, IL-12(p40), osteocalcin (OCN), and matrix metalloproteinase (MMP)-3 than inactive GD patients. All IFNs except IFN-λ1 were correlated with TSHRAb titers. Moreover, TNFSF cytokines, consisting of B-cell-activating factor, sCD30, TNFSF14, PTX-3, sTNF-R2, and TSLP, were associated with TSHRAb levels.

CONCLUSIONS

Serum IFNs could be the most remarkable cytokines in modulating the disease severity and TSHRAb titers in women with full-blown GD. Further molecular-based research to clarify the actual role of IFNs in the disease progression of GD is needed.

Simultaneous measurement of twenty-nine circulating cytokines and growth factors in female patients with overt autoimmune thyroid diseases

Cytokines and growth factors participate in immune responses, and the pathogenesis of autoimmune diseases. Herein, we simultaneously examined differential levels of 29 circulating factors to determine their associations in female patients with overt autoimmune thyroid disease (AITD). We enrolled 40 patients with Graves' disease (GD), 20 patients with Hashimoto's thyroiditis (HT), and 14 healthy controls. Twenty-nine circulating factors were simultaneously measured. GD patients with low thyroid-stimulating hormone at the time of sample collection were defined as having active GD. B-cell activating factor (BAFF) levels were associated with GD and HT (p = .001 and .001, respectively) and interferon (IFN)-α levels were higher in the HT group than in the control group (p = .021). Significant associations of serum BAFF and tumour necrosis factor (TNF)-α levels with free thyroxin (FT4) were present in HT (r = -0.498, p = .026, and r = 0.544, p = .013, respectively). Meanwhile, there were significant associations of FT4 with interleukin (IL)-4 and eotaxin levels in GD (r = 0.354, p = .025 and r = 0.384, p = .014, respectively). In active GD, serum BAFF and eotaxin level were correlated with FT4 levels (r = 0.465, p = .034, and r = 0.463, p = .035, respectively). In conclusion, BAFF is the best circulating indicator to identify GD and HT among all chosen 29 biomarkers, and it could be used to predict the disease severity in HT and active GD. Meanwhile, IFN-α could be another reliable parameter for recognising HT.

Associations of gene polymorphisms in interferon-alpha signature-related genes with autoimmune thyroid diseases

Interferon (IFN)-α treatment predisposes patients to the occurrence of autoimmune thyroid disease (AITD).

METHODS

We investigated associations of single nucleotide polymorphisms (SNPs) of molecules participating in the IFN-α signature, including rs2304204 and rs2304206 of IFN regulatory factor 3 (IRF3), rs1061501 of IRF7, and rs7708392 of TNFA1P3-interacting protein 1 with serum IFN-α levels and AITD in an ethnic Chinese (ie Taiwanese) population. Totally, 319 patients with Graves' disease (GD), 83 patients with Hashimoto's thyroiditis (HT) and 351 healthy controls were recruited.

RESULTS

There were increased percentages of the C allele, and CC and TC + CC genotypes of rs1061501 in GD patients compared to the controls. HT patients had higher serum IFN-α levels compared to the controls, while there was no difference in serum IFN-α levels between patients with GD and controls. However, patients with GD in a remission status had lower serum IFN-α levels than those without remission. On the other hand, the C allele of rs1061501 was only associated with serum IFN-α levels in patients with HT.

CONCLUSIONS

The SNP rs1061501 of IRF7 was associated with the development of GD. Serum IFN-α levels were associated with HT, while they might modify the disease status of GD. Moreover, a genetic effect of rs1061501 on regulating serum IFN-α production was observed in HT.

Serum fibroblast growth factor 23 and mineral metabolism in patients with euthyroid Graves' diseases: a case-control study

This study investigated the alterations of mineral metabolism in patients with Graves' disease (GD) who achieved euthyroidism. They had higher fibroblast growth factor 23 (FGF23) and phosphorus as compared with healthy subjects. Serum FGF23 was negatively correlated with serum phosphorus. These indicated abnormal mineral metabolism even after 1.6 years of euthyroid status.

INTRODUCTION

FGF23 is involved in the mineral homeostasis, especially the regulation of serum phosphorus. Graves' disease (GD) is associated with accelerated bone turnover, hyperphosphatemia, and elevated serum FGF23. Evidence suggested that serum FGF23 decreased after a 3-month treatment of GD. However, it remains unclear whether serum FGF23, serum phosphorus, and other markers of mineral metabolism will be normalized after euthyroid status achieved.

METHODS

A total of 62 patients with euthyroid GD and 62 healthy control subjects were enrolled, and the median duration of euthyroid status was 1.6 years. Endocrine profiles including thyroid function test, autoantibodies, serum FGF23, and bone turnover markers were obtained and compared between the two groups.

RESULTS

Euthyroid GD patients had significantly higher serum FGF23 and phosphorus, and lower 25-hydroxyvitamin D (25(OH)D) and intact parathyroid hormone (iPTH) levels as compared with the control group. Serum FGF23 was significantly and negatively correlated with phosphorus level after adjusted for age, gender, calcium, iPTH, and 25(OH)D in the euthyroid GD group.

CONCLUSION

Serum phosphorus and FGF23 levels remain higher in GD patients even after euthyroid status has been achieved for a median of 1.6 years. Serum FGF23 was negatively correlated with serum phosphorus in euthyroid GD patients. Underlying mechanisms warrant further investigations.

TRIAL REGISTRATION

Registration number: NCT01660308 and NCT02620085.

Fibroblast Growth Factor Receptor Inhibitors Reduce Adipogenesis of Orbital Fibroblasts and Enhance Myofibroblastic Differentiation in Graves' Orbitopathy

Purpose: Orbital fibroblasts are involved in pathogenesis of Graves' orbitopathy (GO). Fibroblast growth factor (FGF) affects fibroblasts of GO. This study aims to investigate the roles of FGF and FGF receptor (FGFR) in GO.Methods: Serum FGF proteins and orbital fibroblast FGFR proteins and mRNAs were measured in GO patients and controls. Orbital fibroblasts of GO were cultured and accessed for changes in proliferation (by nuclei number and MTT), myofibroblastic differentiation (by α-SMA), and adipogenesis (by oil droplets using Oil Red O stain) under FGF1 with or without FGFR inhibitors (FGFRi).Results: Serum FGF1 and FGF2 were increased in GO patients. FGFR1 was the most abundantly expressed FGFR in GO orbital fibroblasts. FGF1 increased GO fibroblast proliferation/adipogenesis and suppressed myofibroblastic differentiation, while FGFRi reversed these effects.Conclusion: FGF signaling may be involved in GO pathogenesis. Manipulation of FGF-FGFR pathway for GO treatment is worthy of further investigation.Registration number on Clinicaltrials.gov: NCT03324022.

Synchronized expressions of serum osteopontin and B cell-activating factor in autoimmune thyroid disease

BACKGROUND

Osteopontin (OPN) is recognized as a potent immunoregulator of autoimmune disease. In the study, we tried to explore the association of serum OPN levels with autoimmune thyroid disease, including Graves' disease (GD) and Hashimoto's thyroiditis (HT), in an ethnic Chinese population.

MATERIALS AND METHODS

We enrolled 131 patients with GD, 33 patients with HT and 123 healthy controls. Serum OPN, B cell-activating factor (BAFF) and interferon (IFN)-α levels were quantified. Graves' disease patients with high thyroid function at the time of sample collection were defined as having active GD, while the other patients were defined as having inactive GD.

RESULTS

Serum OPN levels were higher in active GD than in inactive GD and the control groups (P = 0.001 and P = 0.018, respectively). In GD, significant associations of OPN levels with thyroid-stimulating hormone receptor antibody (TSHRAb) levels were observed in women (r = -0.344, P = 0.002, and r = 0.440, P = 0.004, respectively) but not in men. Osteopontin levels were associated with BAFF levels only in women with GD or HT (r = 0.506, P < 0.001 and r = 0.430, P = 0.025, respectively), but not in men with GD or HT.

CONCLUSIONS

Serum OPN levels were upregulated in active GD, and serum OPN levels were associated with thyroid function and TSHRAb levels in GD. Additionally, OPN levels were correlated with BAFF levels in GD and HT. The associations of OPN levels with clinical phenotypes of GD and BAFF levels showed a dimorphic pattern.

Associations of secreted phosphoprotein 1 and B lymphocyte kinase gene polymorphisms with autoimmune thyroid disease

BACKGROUND

Dysregulation of the type 1 interferon (IFN)-related signalling pathway predisposes one to autoimmune diseases. Possible associations of single-nucleotide polymorphisms (SNPs) of secreted phosphoprotein 1 (SPP1) and B lymphocyte kinase (BLK) of the type 1 IFN-related signalling pathway with autoimmune thyroid disease (AITD) in an ethnic Chinese (ie Taiwanese) population were tested.

METHODS

Totally, 83 Hashimoto's thyroiditis (HT) patients, 319 Graves' disease (GD) patients and 369 controls were enrolled. Genotypes of the two SNPs (rs1126772 and rs1126616) of SPP1 and two SNPs (rs13277113 and rs2736340) of BLK were determined.

RESULTS

Our results showed reduced percentages of the G allele of rs13277113 of BLK in GD (P = 0.037, odds ratio [OR] = 0.78, 95% confidence interval [CI] = 0.62-0.99) and HT (P = 0.002, OR = 0.54, 95% CI = 0.36-0.81), compared to the controls. At the same time, lower frequencies of the C allele of rs2736340 of BLK in GD (P = 0.025, OR = 0.76, 95% CI = 0.60-0.97) and HT (P = 0.003, OR = 0.53, 95% CI = 0.35-0.81) than the controls were also observed. There were significantly higher AT haplotype frequencies of rs1327713 and rs2736340 in GD and HT patients than in the controls (P = 0.025, OR = 1.31, 95% CI = 1.03-1.67, and P = 0.003, OR = 1.89, 95% CI = 1.24-2.87, respectively). Moreover, the anti-microsomal antibody titre was associated with rs2736340.

CONCLUSIONS

Genetic variants of rs13277113 and rs2736340 of BLK were associated with susceptibility to GD, HT and AITD in an ethnic Chinese population. Our results suggest the BLK may participate in the pathogenesis of GD, HT and AITD.

Thyroid Stimulating Hormone Receptor Antibodies in Thyroid Eye Disease-Methodology and Clinical Applications

BACKGROUND

Thyroid stimulating hormone receptor antibodies (TSHR-Ab) cause autoimmune hyperthyroidism and are prevalent in patients with related thyroid eye disease (TED).

PURPOSE

To provide a historical perspective on TSHR-Ab and to present evidence-based recommendations for clinical contemporary use.

METHODS

The authors review the recent literature pertaining to TSHR-Ab in patients with TED and describe the various immunoassays currently used for detecting TSHR-Ab and their clinical applications.

RESULTS

We provide a historical summary and description of the various methods used to detect TSHR-Ab, foremost, the functional TSHR-Ab. Increasing experimental and clinical data demonstrate the clinical usefulness of cell-based bioassays for measurements of functional TSHR-Ab in the diagnosis and management of patients with autoimmune TED and in the characterization of patients with autoimmune-induced hyperthyroidism and hypothyroidism. Thyroid stimulating hormone receptor antibodies, especially the functional stimulating antibodies, are sensitive, specific, and reproducible biomarkers for patients with autoimmune TED and correlate well with clinical disease activity and clinical severity. Unlike competitive-binding assays, bioassays have the advantage of indicating not only the presence of antibodies but also their functional activity and potency.

CONCLUSIONS

Measurement of TSHR-Ab (especially stimulating antibodies) is a clinically useful tool for the management of patients with TED.

Serum BAFF and thyroid autoantibodies in autoimmune thyroid disease

BACKGROUND

This study investigated the association of serum B-lymphocyte activating factor (BAFF) levels with autoimmune thyroid disease (AITD) in a Chinese population.

MATERIALS AND METHODS

We enrolled 221 patients with AITD [170 patients with Graves' disease (GD), 51 patients with Hashimoto's thyroiditis (HT)], and 124 healthy controls. Serum BAFF levels, thyroid function and thyroid autoantibody (TAb) levels, including of thyroid-stimulating hormone receptor antibody (TSHRAb), anti-thyroid peroxidase antibody (Anti-TPO Ab), and antithyroglobulin antibody (ATA), were measured at baseline.

RESULTS

Serum BAFF levels were higher in the GD, HT, and AITD groups than in the control group. Significant correlations were observed between BAFF and TSHRAb levels (r=0.238, p=0.018), between BAFF and Anti-TPO Ab levels (p=0.038), and between BAFF and ATA titers (p=0.025) in women but not in men. In addition, serum BAFF levels were significantly associated with free thyroxine (r=0.430, p=0.004) and TSHRAb (r=0.495, p=0.001) levels in women with active GD but not in those with inactive GD.

CONCLUSIONS

Serum BAFF levels are increased in GD, HT, and AITD. The correlation between serum BAFF and TAb levels exhibits a dimorphic pattern, particularly in active GD.

Analysis of Associations of Human BAFF Gene Polymorphisms with Autoimmune Thyroid Diseases

Background

The B-lymphocyte-activating factor (BAFF) is associated with B-cell functions, and gene polymorphisms of the BAFF have been linked to autoimmune diseases (AIDs). In this study, we explored possible associations of two BAFF single-nucleotide polymorphisms (SNPs), rs1041569 and rs2893321, with autoimmune thyroid diseases (AITDs) in an ethnic Chinese population.

Material and Methods

In total, 319 Graves’ disease (GD), 83 Hashimoto’s thyroiditis (HT) patients, and 369 healthy controls were enrolled. Polymerase chain reaction-restriction fragment length polymorphism and direct sequencing were used to genotype rs2893321 and rs1041569.

Results

There was a significant difference in frequencies of the G allele and AG+GG genotype of rs2893321 between the GD and control groups (p = 0.013, odds ratio (OR) = 0.76, and p = 0.017, OR = 0.68, respectively) and between the AITD and control groups (p = 0.009, OR = 0.76, and, p = 0.014, OR = 0.69, respectively). The AA genotype of rs2893321 was associated with low titers of the thyroid-stimulating hormone receptor antibody (TSHRAb) (p = 0.015) in males but not in females. The AA genotype of rs2893321 was associated with the presence of two different types of thyroid autoantibody (TAb) (TSHRAb and Hashimoto’s autoantibody (anti-thyroglobulin or anti-microsomal antibody)) in females and with that of one type in males.

Conclusions

rs2893321 may be a susceptible genetic variant for the development of GD and AITDs. Associations of rs2893321 with susceptibility to GD and AITDs and the correlation between rs2893321 and TAb exhibit a dimorphic pattern. Additional studies with larger sample sizes are required to confirm our findings.

Bioassays for TSH Receptor Autoantibodies, from FRTL-5 Cells to TSH Receptor-LH/CG Receptor Chimeras: The Contribution of Leonard D. Kohn

Since the discovery 60 years ago of the "long-acting thyroid stimulator" by Adams and Purves, great progress has been made in the detection of thyroid-stimulating hormone (TSH) receptor (TSHR) autoantibodies (TRAbs) in Graves' disease. Today, commercial assays are available that can detect TRAbs with high accuracy and provide diagnostic and prognostic evaluation of patients with Graves' disease. The present review focuses on the development of TRAbs bioassays, and particularly on the role that Leonard D. Kohn had in this. Indeed, 30 years ago, the Kohn group developed a bioassay based on the use of FRTL-5 cells that was characterized by high reproducibility, feasibility, and diagnostic accuracy. Using this FRTL-5 bioassay, Kohn and his colleagues were the first to develop monoclonal antibodies (moAbs) against the TSHR. Furthermore, they demonstrated the multifaceted functional nature of TRAbs in patients with Graves' disease, with the identification of stimulating and blocking TRAbs, and even antibodies that activated pathways other than cAMP. After the cloning of the TSHR, the Kohn laboratory constructed human TSHR-rat luteinizing hormone/chorionic gonadotropin receptor chimeras. This paved the way to a new bioassay based on the use of non-thyroid cells transfected with the Mc4 chimera. The new Mc4 bioassay is characterized by high diagnostic and prognostic accuracy, greater than for other assays. The availability of a commercial kit based on the Mc4 chimera is spreading the use of this assay worldwide, indicating its benefits for these patients with Graves' disease. This review also describes the main contributions made by other researchers in TSHR molecular biology and TRAbs assay, especially with the development of highly potent moAbs. A comparison of the diagnostic accuracies of the main TRAbs assays, as both immunoassays and bioassays, is also provided.

Association of IRF8 gene polymorphisms with autoimmune thyroid disease

BACKGROUND

The occurrence of autoimmune thyroid disease (AITD) is known to have a major adverse effect on interferon (INF)-α treatment. The genetic variant of the INF regulatory factor 8 (IRF8), a type 1 INF regulator, is associated with susceptibility to systemic lupus erythematosus and multiple sclerosis. In this study, we investigated possible associations of the IRF8 polymorphisms, rs17445836 and rs2280381, with AITD in an ethnic Chinese population.

MATERIAL AND METHODS

In total, 278 patients with Graves' disease (GD) and 55 patients with Hashimoto's thyroiditis (HT), and 252 healthy controls were enrolled. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequencing were used for genotyping.

RESULTS

Significantly lower frequencies of the GA genotype and A allele of rs17445836 were found in the HT group than in the control group (P = 0·028, odds ratio (OR) = 4·71 and P = 0·022, OR = 4·40, respectively). Both rs17445836 and rs2280381 were associated with the presence of an antimicrosomal antibody (AmiA), and rs2280381 was also associated with the presence of an antithyroglobulin antibody (ATA) in AITD. Moreover, rs17445836 was associated with the level of AmiA in AITD.

CONCLUSIONS

rs17445836 of IRF8 is a possible genetic variant associated with the development of HT. rs17445836 was associated with the production of thyroid antibody, and the GG genotype of rs17445836 was associated with a higher AmiA titre than the GA genotype.

Autoimmune polyendocrine syndromes. Autoimmun Rev. 2014;13:85-89. [PMID: 24055063 DOI: 10.1016/j.autrev.2013.07.006]

Autoimmune polyendocrine syndromes (APS), also called polyglandular autoimmune syndromes (PGAS), are a heterogeneous group of rare diseases characterized by autoimmune activity against more than one endocrine organs, although non-endocrine organs can be affected. The two major autoimmune polyendocrine syndromes, (type1-type2/APS-1 and APS-2), both have Addison's disease as a prominent component. Further autoimmune polyendocrine syndromes include APS3 and APS4. The major autoimmune polyendocrine syndromes have a strong genetic component with the type 2 syndrome occurring in multiple generations and the type I syndrome in siblings. It is well recognized that more than 20years may elapse between the onset on one endocrinopathy and the diagnosis of the next, for example, almost 40-50% of subjects with Addison's disease will develop an associated endocrinopathy. The discovery of the polyendocrine autoimmune syndromes offered the possibility to understand autoimmune disorders with particular interest for type 1A diabetes and the neuroendocrine immunology (NEI) is further contributing to understand the links.

Significant attenuation of stimulated cortisol in early Graves disease without adrenal autoimmunity

OBJECTIVE

To investigate cortisol responses to adrenocorticotropic hormone during thyrotoxic (G1) and euthyroid (G2) phases in patients with Graves disease (GD) who were without adrenal autoimmunity.

METHODS

Fifteen patients with GD, who were thyrotropin receptor antibody positive and 21-hydroxylase antibody negative, were recruited to this prospective pilot study. A modified short Synacthen test (SST) was performed, in which cortisol was measured every 30 minutes for 2 hours during G1 and G2.

RESULTS

The median times to SST were 3 weeks (G1) and 27 weeks (G2) after diagnosis of GD. Integrated stimulated cortisol levels were significantly lower at G1 in comparison with G2: mean ± standard error of the mean for area under the curve was 78,091.6 ± 4,462.1 nmol/L (G1) versus 89,055 ± 4,434 nmol/L at 120 minutes (G2), P = .017; and for delta area under the curve was 36,309.9 ± 3,526 nmol/L (G1) versus 44,041.7 ± 2,147 nmol/L at 120 minutes (G2), P = .039. Mean cortisol levels were significantly lower for G1 versus G2 at 60, 90, and 120 minutes of the SST (P = .001 to .013). The cortisol level was abnormal in 2 patients (13%) at 30 minutes during G1 but in none during G2. There was no correlation of integrated cortisol with free thyroxine or thyrotropin receptor antibody. There was no significant difference in median adrenocorticotropic hormone level (17 versus 20.4 ng/mL at G1 and G2, respectively; P = .14).

CONCLUSION

Significant attenuation of stimulated cortisol occurs in the early thyrotoxic phase in comparison with the euthyroid phase in patients with GD without adrenal autoimmunity. Clinicians treating patients with GD should have a low threshold for investigating symptoms suggestive of hypoadrenalism at times of "stress."

Clinical review: Clinical utility of TSH receptor antibodies

CONTEXT

TSH receptor antibodies (TRAb) cause Graves' disease (GD) hyperthyroidism. Widely available TRAb measurement methods have been significantly improved recently. However, the role of TRAb measurement in the differential diagnosis of hyperthyroidism, the prediction of remission of GD hyperthyroidism, the prediction of fetal/neonatal thyrotoxicosis, and the clinical assessment of Graves' ophthalmopathy (GO) are controversial.

EVIDENCE ACQUISITION

We reviewed and analyzed the literature reporting primary data on the clinical use of TRAb. We focused our analyses on clinical studies analyzing third-generation TRAb assays.

EVIDENCE SYNTHESIS

The performance of TRAb in the differential diagnosis of overt hyperthyroidism is excellent, with sensitivity and specificity in the upper 90%. TRAb can accurately predict short-term relapses of hyperthyroidism after a course of antithyroid drugs but are less effective in predicting long-term relapses or remissions. Pregnancies in women with GD with negative TRAb are highly unlikely to result in fetal hyperthyroidism, whereas high titers of TRAb in pregnancy require careful fetal monitoring. GD patients with GO frequently have high TRAb levels. However, there are insufficient data to use the test to predict the clinical course of GO and response to treatment.

CONCLUSIONS

Third-generation TRAb assays are suitable in the differential diagnosis of hyperthyroidism. In GD, TRAb should be tested before deciding whether methimazole can be stopped. TRAb should be used in pregnant women with GD to assess the risk of fetal thyrotoxicosis. The use of TRAb in GO requires further studies.

TSH receptor autoantibody immunoassay in patients with Graves' disease: improvement of diagnostic accuracy over different generations of methods. Systematic review and meta-analysis

BACKGROUND

TSH receptor antibodies (TRAb) are the diagnostic hallmark of Graves' disease (GD) and immunoassays for their detection have been available for more than 30 years over three generations of laboratory methods. Despite a growing body of data produced by clinical and laboratory research which demonstrates its elevated sensitivity and specificity, TRAb testing is poorly used for diagnosing GD. The aim of our systematic review and meta-analysis is to verify the diagnostic performance of TRAb detected with 2nd and 3rd generation immunoassay methods.

METHODS

We searched for English articles using MEDLINE with the search terms "TSH receptor antibody assay", "TSH Receptor antibody tests" and "Graves' disease". We analyzed studies reporting on TSH receptor antibody tests performed by quantitative immunoassays, on untreated patients with GD as the index disease (sensitivity) and on a control group of either healthy subjects or patients affected by other thyroid diseases (specificity). A total of 681 titles were initially identified with the search strategy described. 560 publications were excluded based on abstract and title. Full-text review was undertaken as the next step on 111 publications providing data on TRAb testing; 58 articles were subsequently excluded because they did not include untreated GD patients, or used either bioassays or 1st generation immunoassays. 32 were also excluded because they included data only on sensitivity or only on specificity of the assay, or were duplicates. Finally, 21 articles were selected for meta-analysis. Extraction of data from selected articles was performed by two authors independently, using predefined criteria: the number of patients with GD and the number of healthy or diseased controls; specification of the analytical method used to detect TRAb; sensitivity and specificity of the assay.

RESULTS

The meta-analysis showed that the overall pooled sensitivity and specificity of the 2nd and 3rd generation TRAb assays are 97.1% and 97.4%, and 98.3% and 99.2%, respectively, with little difference between the types of immunoassay methods employed (human or porcine receptor, manual or automated procedure). The likelihood of a TRAb-positive individual to have GD is 1367- to 3420-fold greater (depending upon the type of assay) compared to a TRAb-negative person.

CONCLUSIONS

Data from the meta-analysis showed that TRAb measured with 2nd and 3rd generation immunoassay methods have very high sensitivity and specificity in the diagnosis of GD. The difference between 2nd and 3rd generation methods is small and is equally useful. In contrast with recommendations made by clinical endocrinologists who are not familiar with the state of the art in diagnostic technologies of autoimmunology laboratories, we propose a wide application of these tests in clinical practice to screen all hyperthyroid patients.

Monoclonal autoantibodies to the TSH receptor, one with stimulating activity and one with blocking activity, obtained from the same blood sample

OBJECTIVE

Patients who appear to have both stimulating and blocking TSHR autoantibodies in their sera have been described, but the two activities have not been separated and analysed. We now describe the isolation and detailed characterization of a blocking type TSHR monoclonal autoantibody and a stimulating type TSHR monoclonal autoantibody from a single sample of peripheral blood lymphocytes.

DESIGN, PATIENTS AND MEASUREMENTS

Two heterohybridoma cell lines secreting TSHR autoantibodies were isolated using standard techniques from the lymphocytes of a patient with hypothyroidism and high levels of TSHR autoantibodies (160 units/l by inhibition of TSH binding). The ability of the two new monoclonal antibodies (MAbs; K1-18 and K1-70) to bind to the TSHR and compete with TSH or TSHR antibody binding was analysed. Furthermore, the effects of K1-18 and K1-70 on cyclic AMP production in Chinese hamster ovary cells (CHO) cells expressing the TSHR were investigated.

RESULTS

One MAb (K1-18) was a strong stimulator of cyclic AMP production in TSHR-transfected CHO cells and the other (K1-70) blocked stimulation of the TSHR by TSH, K1-18, other thyroid-stimulating MAbs and patient serum stimulating type TSHR autoantibodies. Both K1-18 (IgG1 kappa) and K1-70 (IgG1 lambda) bound to the TSHR with high affinity (0.7 x 10(10) l/mol and 4 x 10(10) l/mol, respectively), and this binding was inhibited by unlabelled K1-18 and K1-70, other thyroid-stimulating MAbs and patient serum TSHR autoantibodies with stimulating or blocking activities. V region gene analysis indicated that K1-18 and K1-70 heavy chains used the same V region germline gene but different D and J germline genes as well as having different light chains. Consequently, the two antibodies have evolved separately from different B cell clones.

CONCLUSIONS

This study provides proof that a patient can produce a mixture of blocking and stimulating TSHR autoantibodies at the same time.

TSH receptor antibody measurements and prediction of remission in Graves' disease patients treated with minimum maintenance doses of antithyroid drugs

Prediction of remission is one of the main problems of antithyroid drug (ATD) therapy for Graves' disease especially in patients who are treated with a minimum maintenance dose of ATD. We evaluated the ability of new sensitive TSH receptor antibody (TRAb) assays to predict remission in Graves' patients using two commercially available kits (TRAb-CT from Cosmic Corporation and TRAb-Dyno from Yamasa Corporation), compared to the original PEG assay. When a euthyroid state was achieved for more than 6 months with methimazole 5 mg/day or propylthiouracil 50 mg/day and thereafter for three months with 5 mg every other day or 50 mg every other day, respectively, we discontinued ATD medication. One year of observation after discontinuation of ATD was completed in 71 patients (60 females, median age 43 years, range 18-71), and TRAb values from these patients were analyzed in relation to prognosis. Twenty-six (37%) of the 71 patients had relapse of thyrotoxicosis and 45 remained euthyroid. The median TRAb levels in the relapse group were significantly higher than those in the remission group (P < 0.05). Relapse occurred in 15/51 patients negative by TRAb-CT, in 11/20 patients positive by TRAb-CT (chi2 = 4.1; P < 0.05), in 11/42 patients negative by TRAb-Dyno and in 15/29 patients positive by TRAb-Dyno (chi2 = 4.8; P < 0.05). By contrast, relapse occurred in 23/64 patients with negative TRAb by PEG assay and in 3/7 patients with PEG assay positive values (n.s.). All patients with TRAb-CT values of 30% inhibition or greater, or TRAb-Dyno values of 3.0 U/L or greater relapsed during the observation period. Thus, measurement of TRAb by the new sensitive assays is useful for prediction of remission in our patients.

Antibodies to TSH-receptor in thyroid autoimmune disease interact with monoclonal antibodies whose epitopes are broadly distributed on the receptor

The hyperthyroidism of Graves' disease (GD) is caused by TSH-receptor (TSH-R) stimulating autoantibodies (TSAb), leading to overproduction of thyroid hormones. We present evidence for TSAb interaction with three distinct regions of the TSH-R, one in immediate vicinity of the carboxy terminal serpentine. Three murine monoclonal antibodies (MoAbs 28.1, A9 and 31.7) directed to amino acids 36-40, 147-228 and 382-415 were labelled and tested for their binding to human recombinant TSH-R on solid phase. All MoAbs bound to TSH-R with a K(d) of 8-12 nm and showed no competition among themselves. We tested 114 sera from euthyroid controls, 118 TBII positive sera from patients with GD (containing TSAb confirmed by bioassays), 16 TBII positive sera from patients with autoimmune thyroid disease (AIT), who were hypothyroid and had TSH blocking antibodies (TBAb), and 20 patients with AIT, who were hypothyroid but negative for all TRAb. Mid-regional MoAb A9 tracer achieved the highest sensitivity in the GD group (72.0%), whereas C-terminal MoAb 31.7 found most sera positive in the AIT group (87.5%). Surprisingly, the N-terminal MoAb 28.1 had the lowest sensitivity in the GD (10.4%) and AIT group (43.8%). Using a mixture of all three tracer MoAbs did not increase the sensitivity in the GD or AIT group, compared to the best single MoAb alone. Median inhibition of MoAb A9 was significantly (P < 0.001) higher than inhibition of MoAbs 28.1 or 31.7 in the group of GD patients but not in other groups. Almost all patient sera with positive reactivity in the MoAb tracer assays had TBII values in the higher range. However, there were many highly TBII positive sera, which did not show a displacement of the MoAb tracers. We conclude that, contrary to some reports, the binding of TSAb and TBAb to the TSH-R is not restricted to distinct and distant epitopes. The middle part of the TSH-R seems to be more relevant for TSAb binding than the N-terminal part, while a proportion of TSAb autoantibodies also binds to a C-terminal epitope of the TSH-R. The method described here is a TSH independent competitive assay for the detection of TSH-R autoantibodies.

A coated tube assay for the detection of blocking thyrotropin receptor autoantibodies

We developed a coated tube assay to discriminate TSH-receptor-stimulating autoantibodies [thyroid-stimulating antibodies (TSAb)] from those autoantibodies blocking TSH binding without intrinsic activation [thyroid-blocking antibodies (TBAb)]. The wild-type TSH receptor in the TSH binding-inhibitory assay was exchanged for a chimeric receptor where a TSAb epitope (amino acids 8-165) was replaced by comparable LH-R residues. Binding of (125)I-labeled TSH to this chimera could be inhibited by sera containing TBAb up to 95%. Sera from 316 patients with Graves' disease and 17 with autoimmune thyroid disease were grouped according to their bioassay activity. At the decision threshold, the chimera A assay had a sensitivity of 78.0% for TBAb with a specificity of 90.2%. In detail, 19 of 22 (86.4%) TBAb sera and 15 of 23 (65.2%) TSAb/TBAb sera were positive but only 32 of 216 (14.0%) TSAb sera and 5 of 72 (6.9%) bioassay negative sera. There was a weak but significant positive correlation (r = 0.46) between the chimera assay and the bioassay for TBAb. This is the first report of a coated tube assay for the determination of TBAb employing an adaptation of the TSH binding-inhibitory format, which could be a useful alternative to the bioassay.

The thyrotropin receptor autoantigen in Graves disease is the culprit as well as the victim

Graves disease, a common organ-specific autoimmune disease affecting humans, differs from all other autoimmune diseases in being associated with target organ hyperfunction rather than organ damage. Clinical thyrotoxicosis is directly caused by autoantibodies that activate the thyrotropin receptor (TSHR). The etiology of Graves disease is multifactorial, with nongenetic factors playing an important role. Of the latter, there is the intriguing possibility that the molecular structure of the target antigen contributes to the development of thyroid-stimulatory autoantibodies (TSAb's). Among the glycoprotein hormone receptors, only the TSHR undergoes intramolecular cleavage into disulfide-linked subunits with consequent shedding of some of the extracellular, autoantibody-binding A subunits. Functional autoantibodies do not arise to the noncleaving glycoprotein hormone receptors. Recently, TSAb's were found to preferentially recognize shed, rather than attached, A subunits. Here we use a new adenovirus-mediated animal model of Graves disease to show that goiter and hyperthyroidism occur to a much greater extent when the adenovirus expresses the free A subunit as opposed to a genetically modified TSHR that cleaves minimally into subunits. These data show that shed A subunits induce or amplify the immune response leading to hyperthyroidism and provide new insight into the etiology of Graves disease.