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

US-based, Prospective, Blinded Study of Thyrotropin Receptor Antibody in Autoimmune Thyroid Disease

CONTEXT

Bioassays provide information on the functionality of thyrotropin receptor antibodies (TSH-R-Ab) and thus may offer more clinical utility than binding assays.

OBJECTIVE

In this prospective, blinded, US-based study, the clinical performance of several TSH-R-Ab assays was compared.

SETTING

US endocrinology clinic.

SUBJECTS

One hundred sixty-two unselected, consecutive, well-documented patients with various thyroid diseases and healthy controls.

INTERVENTION(S)

Blinded TSH-R-Ab measurements.

MAIN OUTCOME MEASURE(S)

Sensitivity and specificity of 4 TSH-R-Ab assays.

RESULTS

The 4 TSH-R-Ab assays were negative in all 42 patients without autoimmune thyroid disease (AITD). In 104 patients with Graves' disease (GD), irrespective of the disease duration, TSH-R-Ab positivity was present in 65 (63%), 67 (65%), and 87 (84%) for the Cobas and Immulite binding assays and stimulatory TSH-R-Ab [thyroid-stimulating immunoglobin (TSI)] bioassay, respectively (TSI vs Immulite P < .0025, TSI vs Cobas P < .0009). Fifteen newly diagnosed GD patients were all positive in the TSI bioassay, but only 11 (73%) were positive in the Cobas and Immulite binding assays. Nine GD patients with biochemical subclinical hyperthyroidism were TSI-positive but Immulite- and Cobas-negative. Two GD patients were blocking TSH-R-Ab [thyroid-blocking immunoglobin (TBI)]-positive and TSI-negative, and the Immulite and Cobas were positive in both. Additional serum samples from AITD patients that consisted of 30 TBI-positive and 10 TSI-positive samples were blindly tested in the binding assays. Only 6 of the 10 TSI-positive samples were positive in both binding assays, and 30 and 28 of the TBI-positive samples were positive in the Cobas and Immulite assays, respectively.

CONCLUSION

Binding TSH-R-Ab assays are less sensitive than TSI bioassays and are not specific for stimulating antibodies. Measuring the function of TSH-R-Ab in a bioassay can provide useful information to clinicians.

Predictive model for the progression of inactive thyroid eye disease: a retrospective study

PURPOSE

This study aimed to develop a model for predicting the progression of inactive thyroid eye disease (TED).

METHODS

We retrospectively analyzed 107 patients with inactive TED, who did not receive any TED treatment during the follow-up period of 3-6 months. A multivariable regression analysis was employed to examine the clinical risk factors influencing the progress of TED and a predictive model based on risk factors was established.

RESULTS

Seventeen (15.9%) patients had progressed at the last observation. Male (p = 0.024), having smoking history (p = 0.009), compound indicator combined the duration of TED and immunosuppressive treatment history before 3 months (p = 0.026) and more severe diplopia (p = 0.015) were found to be the potential risk factors for progression. Among the subset of patients who exhibited progression, there was a notable escalation in the severity of proptosis (p = 0.021), margin reflex distance-1 (p = 0.031), and clinical activity score (p = 0.011). The multivariable stepwise regression analysis identified positive smoking history as well as untreated and having a duration of TED > 12 months as independent risk factors of TED progression. A predictive model including these risk factors was built, with the AUC (Area Under Curve) score of 0.783.

CONCLUSIONS

The predictors of TED progression include smoking history and composite indicators of duration time and treatment history. Our model may provide recommendations for immunosuppressive therapy and prognostic predictions for inactive TED patients preparing for surgery.

Redox mechanisms in autoimmune thyroid eye disease

Thyroid eye disease (TED) is an autoimmune condition affecting the orbit and the eye with its adnexa, often occurring as an extrathyroidal complication of Graves' disease (GD). Orbital inflammatory infiltration and the stimulation of orbital fibroblasts, triggering de novo adipogenesis, an overproduction of hyaluronan, myofibroblast differentiation, and eventual tissue fibrosis are hallmarks of the disease. Notably, several redox signaling pathways have been shown to intensify inflammation and to promote adipogenesis, myofibroblast differentiation, and fibrogenesis by upregulating potent cytokines, such as interleukin (IL)-1β, IL-6, and transforming growth factor (TGF)-β. While existing treatment options can manage symptoms and potentially halt disease progression, they come with drawbacks such as relapses, side effects, and chronic adverse effects on the optic nerve. Currently, several studies shed light on the pathogenetic contributions of emerging factors within immunological cascades and chronic oxidative stress. This review article provides an overview on the latest advancements in understanding the pathophysiology of TED, with a special focus of the interplay between oxidative stress, immunological mechanisms and environmental factors. Furthermore, cutting-edge therapeutic approaches targeting redox mechanisms will be presented and discussed.

Thyroid stimulating immunoglobulin concentration is associated with disease activity and predicts response to treatment with intravenous methylprednisolone in patients with Graves' orbitopathy

Background

Thyroid stimulating immunoglobulins (TSI) play a central role in the pathogenesis of Graves' orbitopathy (GO), while soluble interleukin-2 receptor (sIL-2R) is a marker for T-cell activity. We investigated TSI and sIL-2R levels in relation to thyroid function, disease activity and severity and response to treatment with intravenous methylprednisolone (IVMP) in patients with GO.

Methods

TSI (bridge-based TSI binding assay), sIL-2R, TSH and fT4 levels were measured in biobank serum samples from 111 GO patients (37 male, 74 female; mean age 49.2 years old) and 25 healthy controls (5 male, 20 female; mean age 39.8 years old). Clinical characteristics and response to treatment were retrospectively retrieved from patient files.

Results

Higher sIL-2R levels were observed in GO patients compared to controls (p < 0.001). sIL-2R correlated with fT4 (r = 0.26), TSH (r = -0.40) and TSI (r = 0.21). TSI and sIL-2R concentrations were higher in patients with active compared to inactive GO (p < 0.001 and p < 0.05, respectively). Both TSI and sIL-2R correlated with total clinical activity score (CAS; r = 0.33 and r = 0.28, respectively) and with several individual CAS items. Cut-off levels for predicting active GO were 2.62 IU/L for TSI (AUC = 0.71, sensitivity 69%, specificity 69%) and 428 IU/mL for sIL-2R (AUC = 0.64, sensitivity 62%, specificity 62%). In multivariate testing higher TSI (p < 0.01), higher age (p < 0.001) and longer disease duration (p < 0.01) were associated with disease activity. TSI levels were higher in patients with a poor IVMP response (p = 0.048), while sIL-2R levels did not differ between responders and non-responders. TSI cut-off for predicting IVMP response was 19.4 IU/L (AUC = 0.69, sensitivity 50%, specificity 91%). In multivariate analysis TSI was the only independent predictor of response to IVMP (p < 0.05).

Conclusions

High TSI levels are associated with active disease (cut-off 2.62 IU/L) and predict poor response to IVMP treatment (cut-off 19.4 IU/L) in GO. While sIL-2R correlates with disease activity, it is also related to thyroid function, making it less useful as an additional biomarker in GO.

Automated evaluation of parapapillary choroidal microvasculature in thyroid eye disease

PURPOSE

The purpose of the study was to investigate the parapapillary choroidal microvasculature in thyroid eye disease (TED) using optical coherence tomography angiography (OCTA).

METHODS

Only one eye of each subject was included in the study. Patients with TED and controls were included in the study. Participants were divided into three groups: control, inactive TED (ITED) and active TED (ATED). OCTA scans of the optic discs were obtained in a 4.5 × 4.5-mm rectangular area. Radial peripapillary capillary (RPC) density and peripapillary retinal nerve fibre layer (pRNFL) thickness were automatically calculated by the device software. Parapapillary choroidal microvasculature (PPCMv) density was automatically calculated using MATLAB software.

RESULTS

Forty-one patients with TED and 40 controls were included in the study. RPC density was significantly decreased in the ATED and dysthyroid optic neuropathy (DON) group compared to the controls and ITED group. There was significant increase in pRNFL in the ATED group. PPCMv density increased in the ATED group compared to the controls in whole ring area. The RPC density was significantly correlated with the TSHr Ab level (r < - 0.396, p < 0.001). Clinical activity score correlated positively with PPCMv density (r = 0.349, p = 0.001) but negatively with RPC density (r = - 0.321, p = 0.004).

CONCLUSION

Changes in peripapillary microvascular perfusion may play a role in the development of DON. As the severity of TED increases with clinical activity, so do the changes observed in peripapillary parameters. The decrease in RPC density may be due to compression caused by optic disc oedema, which may result in reduced blood flow. The increase in PPCMv density may be related to factors such as orbital congestion.

Sex-specific risk factors associated with graves' orbitopathy in Korean patients with newly diagnosed graves' disease

OBJECTIVE

To assess sex-specific risk factors for Graves' orbitopathy (GO) in newly diagnosed Graves' disease (GD) patients.

METHODS

A retrospective cohort study was conducted using the National Health Insurance Service's sample database, which consisted of 1,137,861 subjects from 2002 to 2019. The international classification of disease-10 codes was used to identify those who developed GD (E05) and GO (H062). A multivariable Cox proportional hazards model was used to estimate the effect of risk factors on GO development.

RESULTS

Among 2145 male and 5047 female GD patients, GO occurred in 134 men (6.2%) and 293 women (5.8%). A multivariable Cox regression model revealed that GO development was significantly associated with younger age (HR = 0.84, 95% CI = 0.73-0.98), low income (HR = 0.55, 95% CI = 0.35-0.86), and heavy drinking (HR = 1.79, 95% CI = 1.10-2.90) in men, and with younger age (HR = 0.89, 95% CI = 0.81-0.98), lower body mass index (HR = 0.55, 95% CI = 0.33-0.90), high total cholesterol (HR = 1.04, 95% CI = 1.01-1.06), hyperlipidaemia (HR = 1.37, 95% CI = 1.02-1.85), and lower statin dose (HR = 0.37, 95% CI = 0.22-0.62) in women. There was no association between smoking and GO development in both men and women.

CONCLUSIONS

The risk factors for GO development were sex-dependent. These results show the need for more sophisticated attention and support considering sex characteristics in GO surveillance.

A NOVEL MONOCLONAL ANTIBODY DEGRADES THE THYROTROPIN RECEPTOR AUTOANTIBODIES IN GRAVES' DISEASE

OBJECTIVE

Autoantibodies (Ab) against the thyrotropin receptor (TSH-R-Ab) are key mediators for the pathogenesis of Graves' disease (GD). TSH-R-Ab degradation was evaluated using several immunoassays within an exploratory, controlled trial in patients with GD receiving a monoclonal antibody (mAb) targeting the neonatal crystallizable fragment receptor (FcRn).

METHODS

Serial measurements of TSH-R-Ab serum levels were performed using three different binding and cell-based assays in GD patients either on medication or on placebo.

RESULTS

In contrast to placebo where no changes were observed, a 12-week mAb therapy led to an early and significant decrease (> 60%) of the serum TSH-R-Ab serum levels in patients with thyroidal and extra-thyroidal GD, as unanimously shown in all three assays. These marked changes were noted already at week seven post baseline (P<0.0001 for the binding immunoassay and for the luciferase (readout) bioassay. The three TSH-R-Ab binding and bioassays highly correlated in the samples of both study groups (binding immunoassay versus luciferase bioassay r = 0.91, P < 0.001, binding vs. cyclic adenosine monophosphate (cAMP) bioassay, r = 0.86, P < 0.001, luciferase versus cAMP bioassay, r = 0.71, P = 0.006). The serological results correlated with the course of the extra-thyroidal clinical parameters of GD, i.e. clinical activity score and proptosis.

CONCLUSIONS

Targeting the FcRn markedly reduces the disease-specific TSH-R-Ab in patients with GD. The novel and rapid TSH-R-Ab bioassay improves diagnosis and management of GD patients.

Traditional Chinese medicine in thyroid-associated orbitopathy

PURPOSE

Orbital fibroblasts (OF) are considered the central target cells in the pathogenesis of thyroid-associated orbitopathy (TAO), which comprises orbital inflammation, orbital tissue edema, adipogenesis, fibrosis, oxidative stress and autophagy. Certain active ingredients of traditional Chinese medicine (TCM) demonstrated inhibition of TAO-OF in pre-clinical studies and they could be translated into novel therapeutic strategies.

METHODS

The pertinent and current literature of pre-clinical studies on TAO investigating the effects of active ingredients of TCM was reviewed using the NCBI PubMed database.

RESULTS

Eleven TCM compounds demonstrated inhibition of TAO-OF in-vitro and three of them (polydatin, curcumin, and gypenosides) resulted in improvement in TAO mouse models. Tanshinone IIA reduced inflammation, oxidative stress and adipogenesis. Both resveratrol and its precursor polydatin displayed anti-oxidative and anti-adipogenic properties. Celastrol inhibited inflammation and triptolide prevented TAO-OF activation, while icariin inhibited autophagy and adipogenesis. Astragaloside IV reduced inflammation via suppressing autophagy and inhibited fat accumulation as well as collagen deposition. Curcumin displayed multiple actions, including anti-inflammatory, anti-oxidative, anti-adipogenic, anti-fibrotic and anti-angiogenic effects via multiple signaling pathways. Gypenosides reduced inflammation, oxidative stress, tissue fibrosis, as well as oxidative stress mediated autophagy and apoptosis. Dihydroartemisinin inhibited OF proliferation, inflammation, hyaluronan (HA) production, and fibrosis. Berberine attenuated inflammation, HA production, adipogenesis, and fibrosis.

CONCLUSIONS

Clinical trials of different phases with adequate power and sound methodology will be warranted to evaluate the appropriate dosage, safety and efficacy of these compounds in the management of TAO.

A retrospective study of clinical features and prognosis of patients with Graves' disease and ophthalmopathy

OBJECTIVE

To retrospectively investigate the clinical characteristics of patients with Graves' disease (GD) accompanied by ophthalmopathy (GO) and the prognosis of single 131I therapy.

METHODS

In total, 665 patientswith Graves' disease were enrolled in this study, including 115 patients with GO and 550 patients without GO. On the one hand, the clinical characteristics of the two groups were recorded. On the other hand, the prognosis after more than 6 months of 131I therapy was divided into three groups: recovered, hypothyroidism and unhealed.

RESULTS

Compared with GD-alone patients, GD patients with GO were younger, had a higher thyrotrophin receptor antibody (TRAb), heavier thyroid mass and higher dose of single 131I therapy (all P < 0.05). Furthermore, patients were younger in the clinical active score ≥3 group and had higher FT4 level in the mild GO group (all P < 0.05). Among these, age and TRAb were independent risk factors for GO in GD patients (P < 0.05). When age was <52.5 years and TRAb was >24.01 IU/L, GD patients were more likely to develop GO (P < 0.001). After at least 6 months of single 131I therapy, compared with GD-alone patients, the prognosis was poor in GD patients with GO (P < 0.05).

CONCLUSION

Young GD patients with heavy thyroid mass and high TRAb are more likely to have GO. Younger GO patients are more likely to be active stage and the level of thyroid function was inversely correlated with the severity of GO. When the age and TRAb have exceeded the cutoff value, we should pay more attention to the occurrence of GO and shorten the follow-up interval appropriately. Patients with GD combined with GO have a poor prognosis.

Clinical relevance of thyroid-stimulating immunoglobulin as a biomarker of the activity of thyroid eye disease

BACKGROUND/OBJECTIVES

Although it has been reported that thyroid-stimulating immunoglobulin (TSI) is associated with the clinical characteristics of thyroid eye disease (TED), there is a paucity of literature regarding the role of TSI in diagnosing active TED. This study investigated the relationship between the level of TSI and the activity of TED and assessed the cut-off value of TSI discriminating active TED from inactive TED.

METHODS

This cross-sectional study included 101 patients with TED. TSI was quantitatively measured with a cell-based bioassay using a chimeric TSH receptor and a cyclic adenosine monophosphate response element-dependent luciferase. The association between TSI and a variety of demographic and clinical features of TED was analysed. Multivariate regression analysis was performed to determine possible independent factors affecting the level of TSI.

RESULTS

TSI level was higher in males than in females (p = 0.023) and smokers than in nonsmokers (p = 0.004). TSI level was inversely correlated with the duration of ocular symptoms (r = -0.295, p = 0.003). The level of TSI was also significantly different when compared to the thyroid function (p = 0.003), TED activity (p < 0.001), and TED severity (p = 0.001). Multivariate regression analysis revealed a significant relationship between TED activity and thyroid function jointly and the TSI level. The cut-off level of TSI for predicting active TED was a specimen-to-reference ratio of 406.7 (p < 0.001, area under the curve = 0.847, sensitivity 77.4%, specificity 81.3%).

CONCLUSIONS

TSI was a functional biomarker strongly associated with TED activity even after being adjusted by other clinical characteristics. Serum TSI level may help identify patients with active TED in clinics.

Novel Insight into Non-Genetic Risk Factors of Graves' Orbitopathy

An assessment of the risk of Graves' orbitopathy (GO) is an important challenge in Graves' disease (GD) management. The purpose of this study was to compare non-genetic parameters in GD patients with and without GO in order to find novel risk factors and to verify the factors already reported. A total number of 161 people, 70 with GO and 91 non-GO patients were included in this study. GO was confirmed to be associated with smoking, older age, higher TSH receptor antibodies (TRAb) and lower thyroglobulin antibody (TgAb) levels and hypercholesterolemia. We demonstrated the latter correlation even for only a mild increase in LDL cholesterol. Importantly, our study provides novel potential GO risk factors, including higher serum creatinine levels, higher MCV and lower PLT. If further confirmed, these new, simple and easily accessible potential GO markers may constitute valuable auxiliary markers in GO risk assessments. We additionally proved that in moderate to severe GO, gender-related differences attenuate. No impact of vitamin D deficiency in GO development in patients with 25-hydroxyvitamin D [25(OH)D] > 20 ng/mL was found. The present report provides a set of GO risk factors, which can be used as a precise tool for an individual GO risk assessment.

Thinking inside the box: Current insights into targeting orbital tissue remodeling and inflammation in thyroid eye disease

Thyroid eye disease (TED) is an autoimmune disorder that manifests in the orbit. In TED, the connective tissue behind the eye becomes inflamed and remodels with increased fat accumulation and/or increased muscle and scar tissue. As orbital tissue expands, patients develop edema, exophthalmos, diplopia, and optic neuropathy. In severe cases vision loss may occur secondary to corneal scarring from exposure or optic nerve compression. Currently there is no cure for TED, and treatments are limited. A major breakthrough in TED therapy occurred with the FDA approval of teprotumumab, a monoclonal insulin-like growth factor 1 receptor (IGF1R) blocking antibody. Yet, teprotumumab therapy has limitations, including cost, infusion method of drug delivery, variable response, and relapse. We describe approaches to target orbital fibroblasts and the complex pathophysiology that underlies tissue remodeling and inflammation driving TED. Further advances in the elucidation of the mechanisms of TED may lead to prophylaxis based upon early biomarkers as well as lead to more convenient, less expensive therapies.

Drug safety in thyroid eye disease - a systematic review

INTRODUCTION

The autoimmune-induced thyroid eye disease (TED) is a frequent extrathyroidal manifestation of Graves' disease and less frequently of Hashimoto's thyroiditis. Pathognomonic clinical signs, i.e. exophthalmos, double vision, and inflammation of the orbital tissue cause physical, ophthalmic, and socio-psychological limitations.

AREAS COVERED

PubMed and MeSH database were searched for specific guidelines, randomized controlled trials, prospective clinical studies, systematic reviews and meta-analyses pertaining to the safety profile of currently administered immunosuppressive agents for the treatment of TED. Occurred adverse events (AE), severe AE (SAE), side effects (SE), and severe SE (SSE) were classified according to the standardized medical dictionary for regulatory activities (MedDRA).

EXPERT OPINION

This novel systematic analysis offers an overview of potential AE, SAE and SE for currently recommended immunosuppressive drugs for the treatment of TED. Non-specific, anti-inflammatory drugs and more specific, targeted biologicals are treatment options for active and severe TED. Critical evaluation of the pertinent literature confirms an evidence-based, beneficial efficacy/risk ratio of the current first-line and second-line treatment recommendations endorsed by the European Society of Endocrinology. However, further large, well-conceived trials are mandatory to enhance our knowledge and experience with novel specific small molecules and/or monoclonal antibodies targeting the key autoantigens in TED.

MicroRNA-577 aggravates bone loss and bone remodeling by targeting thyroid stimulating hormone receptor in hyperthyroid-associated osteoporosis

Traditionally, hyperthyroid-associated osteoporosis has been considered to be the result of increased thyroid hormone levels. The pathogenesis of hyperthyroid-associated osteoporosis remains unclear. Thyroid stimulating hormone receptor (TSHR) is closely associated with osteoporosis. Our study aimed to explore the role of TSHR and its upstream microRNA (miRNA) in hyperthyroid-associated osteoporosis. Bioinformatics analysis (starBase and Targetscan) and a wide range of experiments including reverse-transcription quantitative polymerase chain reaction, luciferase reporter, western blot analysis of osteogenic differentiation markers including OSX, OCN, ALP, OPN, and COL1, hematoxylin and eosin staining, Alizarin Red staining assays were used to explore the function and mechanism of TSHR in hyperthyroid-associated osteoporosis. First, we observed that TSHR was downregulated in bone marrow mesenchymal stem cells (BMSCs) isolated from rats after culture in osteogenic medium for 7 days. Functionally, overexpression of TSHR accelerates BMSC osteogenic differentiation. Mechanistically, we predicted four potential miRNAs for TSHR. MiR-577 was validated to bind with TSHR. Rescue assays showed that miR-577 overexpression inhibited BMSC osteogenic differentiation via targeting TSHR. In vivo experiments showed that miR-577 aggravated bone loss and bone remodeling and our data showed that it is achieved by targeting TSHR in hyperthyroid-associated osteoporosis. This finding may deep our understanding of the pathogenesis of hyperthyroid-associated osteoporosis.

The risk factors for Graves' ophthalmopathy

PURPOSE

This review aimed to provide an overview of current research into the risk factors for Graves' ophthalmopathy (GO).

METHODS

To find information about the risk factors for GO, the research database PubMed was searched and relevant articles were obtained to extract information about risk factors.

RESULTS

Smoking has been widely accepted as an important risk factor and cigarette smoking cessation has been shown to improve the outcome and decrease the onset of GO. Radioactive iodine on the thyroid may induce hyperthyroidism and increase the occurrence of GO. Selenium deficiency is a risk factor for GO and the supplementation of selenium has been an adjuvant therapy. Decreasing stressful life events (SLE) may help improve GO. Imbalance in intestinal flora is essential to GO, with Yersinia enterocolitica and Escherichia coli both increased in the digestive tract of the individual with GO. In addition, controlling serum cholesterol may help improve GO since adipogenesis is an important pathological change in its pathogenesis. Considering the correlation between Graves' disease and GO, maintaining normal thyroid function hormone level is the first-line therapeutic strategy to prevent progression of GO. An increase in antibodies such as TSHR and IGF-1R is the main predictor of GO. Besides, gender and gene polymorphism are also risk factors towards GO.

CONCLUSIONS

Risk factors for GO arise from five sources: physical and chemical environment, social-psychological environment, biological environment, the human organism, and genetic codes. Risk factors within these categories may interact with each other and their mechanisms in promoting the development of GO are complex. Research into risk factors for GO may promote emerging fields related to GO such as control of autoantibodies and intestinal microbiota.

Diagnostic accuracy of Immulite® TSI immunoassay for thyroid-associated orbitopathy in patients with recently diagnosed Graves' hyperthyroidism

PURPOSE

The Immulite® thyroid stimulating immunoglobulin (TSI) immunoassay is a relatively new commercial assay that has shown good diagnostic accuracy in Graves' hyperthyroidism (GH). However, its clinical utility in thyroid-associated orbitopathy (TAO) is less clear. The purpose of this study was to assess the diagnostic accuracy of the Immulite® TSI immunoassay for TAO and investigate the associations between TSI and other clinical measures.

METHODS

One hundred and forty patients that had been diagnosed with GH within the previous 12 months were recruited. Identification and grading of TAO were performed at enrolment and serum samples were analysed using the Immulite® TSI immunoassay.

RESULTS

Of the 140 participants recruited, 75 (53.6%) had TAO. Age, sex and time since GH diagnosis were similar between those with and without TAO (p ≥ 0.300). TSI level tended to decrease with increasing time from GH diagnosis (Spearman's ρ - 0.28, 95% CI - 0.43, - 0.12). TSI levels were higher among those with than those without TAO (median 4.0 vs. 2.7 IU/L, respectively, p = 0.037). There was no correlation between TSI level and inflammatory index score (ρ = 0.14, 95% CI - 0.03, 0.30) or clinical severity (p = 0.527) among those with TAO. TSI level showed poor diagnostic accuracy for TAO (area under the receiver operating characteristic curve 0.60, 95% CI 0.51, 0.70).

CONCLUSIONS

Although Immulite® TSI level was higher in the presence of TAO, it showed poor diagnostic accuracy and no correlation with clinical markers of TAO severity or activity.

A cyclic peptide significantly improves thyroid function, thyrotropin-receptor antibodies and orbital mucine /collagen content in a long-term Graves' disease mouse model

BACKGROUND

BALB/c mice which received long-term immunizations of adenovirus (Ad) expressing thyrotropin receptor A-subunits (TSHR) developed stable Graves' disease (GD). TSHR-derived cyclic peptide 19 (P19) was identified as effective therapy in this model.

METHODS

In Ad-TSHR mice, we investigated shorter disease intervals up to 4 months for histological alterations of the orbits, fine tuning of anti-TSHR antibodies (Ab) and free thyroxine (fT4) hormone levels by using novel detection methods in an independent laboratory. Therapy (0.3 mg/kg P19 or vehicle) was given intravenously after the fourth Ad-TSHR immunization (week 11) and continued until week 19.

RESULTS

Thyrotropin binding inhibitory immunoglobulins (TBII, bridge immunoassay), blocking (TBAb) and stimulating (TSAb) TSHR-Ab (both cell-based bioassays) and serum levels of fT4 were significantly elevated at week 11 in Ad-TSHR-immunized mice versus none in control mice. For the first time, TSAb, TBAb, and thyroperoxidase-Ab were detected in 17 of 19, 12/19 and 6/19 Ad-TSHR immunized mice, respectively at week 21. Also, for the first time, this study showed that P19 treatment markedly reduced serum TBII (p < 0.0001), serum fT4 (p = 0.02), and acidic mucins and collagen content in the orbital tissue of Ad-TSHR-immunized mice.

CONCLUSION

P19 significantly improved thyroid function, confirming previous results in an independent second laboratory. A relevant shift of anti-TSHR antibody subpopulations in response to P19 therapy may help explain its immunological effects. Moreover, P19 exerted a beneficial effect on mucine and collagen content of orbital tissue. Hence, P19 offers a potential novel therapeutic approach for GD and associated orbitopathy.

A data-driven approach for the discovery of biomarkers associated with thyroid eye disease

Background

Thyroid eye disease (TED) is the most common autoimmune disease and usually occurs in patients with hyperthyroidism. In this disease, eye-related tissue, such as eye muscles, eyelids, tear glands, etc., become inflated, which causes the eyes and eyelids to become red, swollen, and uncomfortable. The pathophysiology of this disease is still poorly known.

Aim

This study aims to discover potential biomarkers and regulatory pathways of TED which will not only help to diagnose the disease and understand orbital involvement in thyroid dysfunction but also provide an insight for better therapeutics.

Methods

We applied a data-driven approach by combining gene biomarkers both from published literature and computationally predicted from microarray gene expression data. Further, the DAVID tool is used for Gene Ontology-based enrichment analysis.

Results

We obtained a total of 22 gene biomarkers, including 18 semi-automatically curated from the literature and 4 predicted using data-driven approaches, involved in the pathogenesis of TED that can be used as potential information for therapeutic targets. Further, we constructed a regulatory pathway of TED biomarkers comprises of 310 connected components, and 1134 interactions using four prominent interaction databases.

Conclusion

This constructed pathway can be further utilized for disease dynamics and simulation studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-01903-9.

Thyrotropin receptor antibodies and Graves' orbitopathy

CONTEXT AND PURPOSE

The thyrotropin receptor (TSHR) is the key autoantigen in Graves' disease (GD) and associated orbitopathy (GO). Antibodies targeting the TSHR (TSHR-Ab) impact the pathogenesis and the course of GO. This review discusses the role and clinical relevance of TSHR-Ab in GO.

METHODS

Review of the current and pertinent literature.

RESULTS

GO is the most common extrathyroidal manifestation of GD and is caused by persistent, unregulated stimulation of TSHR-expressing orbital target cells (e.g. fibroblasts and pre-adipocytes). Serum TSHR-Ab and more specifically, the stimulatory Ab (TSAb) are observed in the vast majority of patients with GD and GO. TSHR-Ab are a sensitive serological parameter for the differential diagnosis of GO. TSHR-Ab can be detected either with conventional binding immunoassays that measure binding of Ab to the TSHR or with cell-based bioassays that provide information on their functional activity and potency. Knowledge of the biological activity and not simply the presence or absence of TSHR-Ab has relevant clinical implications e.g. predicting de-novo development or exacerbation of pre-existing GO. TSAb are specific biomarkers of GD/GO and responsible for many of its clinical manifestations. TSAb strongly correlate with the clinical activity and clinical severity of GO. Further, the magnitude of TSAb indicates the onset and acuity of sight-threatening GO (optic neuropathy). Baseline serum values of TSAb and especially dilution analysis of TSAb significantly differentiate between thyroidal GD only versus GD + GO.

CONCLUSION

Measurement of functional TSHR-Ab, especially TSAb, is clinically relevant for the differential diagnosis and management of GO.

A Novel Long-Term Graves' Disease Animal Model Confirmed by Functional Thyrotropin Receptor Antibodies

INTRODUCTION

A novel long-term murine model for Graves' disease (GD) using repeated, long-term immunizations with recombinant adenovirus expressing the extracellular A-subunit of the human thyrotropin receptor (Ad-TSHR) was applied to evaluate the functional anti-TSHR-antibody (TSHR-Ab) profile.

METHODS

BALB/c mice received 7 immunizations with either 10¹⁰ plaque-forming units of Ad-TSHR or control Ad-GFP. Naïve (nonimmuized native) mice were also studied. Three 3-weekly immunizations were followed by 4-weekly boosts until the 7th immunization. Blocking (TBAb) and stimulating (TSAb) TSHR-Ab were measured with bioassays. Assay cut-offs for TBAb/TSAb were at 34% inhibition and a specimen-to-reference ratio (SRR) of 140%.

RESULTS

Nineteen (8 Ad-TSHR-, 4 Ad-GFP-immunized, and 7 native) mice were investigated. All native mice were negative for TSHR-binding inhibitory immunoglobulins (TBII) prior to immunization. Native and Ad-GFP mice were negative in weeks 17 and 27 for TBII and TBAb/TSAb. In native mice, the free thyroxine (fT4) levels (median [25th percentile; 75th percentile]) were in the upper normal range (1.2 ng/mL [1.1; 1.6]) prior to immunization, at weeks 17 (2.2 ng/mL [2.1; 2.4]) and 27 (1.4 ng/mL [1.1; 1.7]), respectively. In contrast, in Ad-TSHR-immunized mice, fT4 values were markedly increased at weeks 17 (4.4 ng/mL [3.9; 6]) and 27 (4.5 ng/mL [4.2; 6]) compared to those in Ad-GFP mice (2 ng/mL [1.8; 2.1] and 1.4 ng/mL [1.1; 1.6]), respectively (p = 0.0008, p = 0.001). In contrast, at week 17, in Ad-TSHR mice, the mean TBII, TBAb, and TSAb levels were 40 IU/L (40; 40); 62% inhibition (38; 69), and 116% SRR (97; 185), respectively; at week 27, they were 40 IU/L (39; 40); 65% inhibition (34; 80) and 95% SRR (63; 187), respectively. Three serum samples from Ad-TSHR mice (38%) demonstrated dual TBAb/TSAb positivity.

CONCLUSIONS

TBAb/TSAb were highly prevalent in Ad-TSHR-immunized mice, thus confirming the successful establishment of a novel, long-term murine model for GD. All TBAb- and TSAb-positive Ad-TSHR-immunized mice were TBII-positive. Thus, the binding immunoassay did not differentiate between TSHR-Ab functionality.

Advances in steroid sparing medical management of active thyroid eye disease

Thyroid eye disease (TED) is an autoimmune inflammatory disease of the orbit and the most common extrathyroidal manifestation of Graves disease. The release of pro-inflammatory cytokines is associated with inflammation of the ocular surface and lacrimal gland along with periorbital skin erythema and edema. Resultant tissue remodeling, fibrosis, and fat deposition can impart permanent physical changes to the ocular adnexa with effects on function and cosmesis. These changes occur in the active phase of disease, and it is during this time that steroids are often relied on to help alleviate symptoms. Due to the common and predictable side effects of long-term and high-dose steroid use, there has been a continuous effort to find alternative steroid-sparing medical management options for TED. This review highlights the various research studies that support the use of these medications.

Prospective Trial of Functional Thyrotropin Receptor Antibodies in Graves Disease

CONTEXT

Scarce data exist regarding the relevance of stimulatory (TSAb) and blocking (TBAb) thyrotropin receptor antibodies in the management of Graves disease (GD).

OBJECTIVE

To evaluate the clinical utility and predictive value of TSAb/TBAb.

DESIGN

Prospective 2-year trial.

SETTING

Academic tertiary referral center.

PATIENTS

One hundred consecutive, untreated, hyperthyroid GD patients.

METHODS

TSAb was reported as percentage of specimen-to-reference ratio (SRR) (cutoff SRR < 140%). Blocking activity was defined as percent inhibition of luciferase expression relative to induction with bovine thyrotropin (TSH, thyroid stimulating hormone) alone (cutoff > 40% inhibition).

MAIN OUTCOME MEASURES

Response versus nonresponse to a 24-week methimazole (MMI) treatment defined as biochemical euthyroidism versus persistent hyperthyroidism at week 24 and/or relapse at weeks 36, 48, and 96.

RESULTS

Forty-four patients responded to MMI, of whom 43% had Graves orbitopathy (GO), while 56 were nonresponders (66% with GO; P < 0.01). At baseline, undiluted serum TSAb but not thyroid binding inhibitory immunoglobulins (TBII) differentiated between thyroidal GD-only versus GD + GO (P < 0.001). Furthermore, at baseline, responders demonstrated marked differences in diluted TSAb titers compared with nonresponders (P < 0.001). During treatment, serum TSAb levels decreased markedly in responders (P < 0.001) but increased in nonresponders (P < 0.01). In contrast, TBII strongly decreased in nonresponders (P = 0.002). All nonresponders and/or those who relapsed during 72-week follow-up period were TSAb-positive at week 24. A shift from TSAb to TBAb was noted in 8 patients during treatment and/or follow-up and led to remission.

CONCLUSIONS

Serum TSAb levels mirror severity of GD. Their increase during MMI treatment is a marker for ongoing disease activity. TSAb dilution analysis had additional predictive value.

Role of a new bioassay for thyroid-stimulating antibodies (aequorin TSAb) in Graves' ophthalmopathy

Graves' ophthalmopathy (GO) is characterized by an autoimmune reaction against thyrotropin (TSH) receptors and is diagnosed by TSH receptor antibody (TRAb). A novel assay for thyroid-stimulating antibody (TSAb) was recently introduced using a frozen Chinese hamster ovary cell line expressing TSH receptors, cyclic adenosine monophosphate (cAMP)-gated calcium channel, and aequorin (aequorin TSAb). The aim of this study was to evaluate the role of aequorin TSAb in GO. We studied 136 Japanese patients with GO (22 euthyroid and 8 hypothyroid GO patients) at our hospital. TRAbs were estimated by first generation TRAb (TRAb 1^st), second generation TRAb (hTRAb 2^nd), conventional porcine TSAb, and the new aequorin TSAb assays. Aequorin TSAb, porcine TSAb, TRAb 1^st, and hTRAb 2^nd were positive in 125/136 (92%), 110/136 (81%), 81/130 (62%), and 93/114 (82%) patients, respectively. In patients with hyperthyroid GO, they were positive in 98/106 (98%), 96/106 (91%), 78/101 (77%), and 84/93 (90%) patients, respectively. In patients with euthyroid GO, they were positive in 19/22 (86%), 9/22 (41%), 1/21 (5%), and 6/17 (35%) patients, respectively. Aequorin TSAb levels were significantly related to TRAb 1^st (r = 0.4172, p < 0.0001), hTRAb 2^nd (r = 0.2592, p < 0.0001), and porcine TSAb (r = 0.4665, p < 0.0001). Clinical activity score (CAS) was significantly greater in patients with high titers of aequorin TSAb than in those with low titers. Aequorin TSAb levels were significantly related to the signal intensity ratio of the enlarged eye muscle and proptosis evaluated by MRI before steroid pulse therapy. Aequorin TSAb assay was more sensitive than the conventional assays, especially in euthyroid GO.

A Novel Anti-CD40 Monoclonal Antibody, Iscalimab, for Control of Graves Hyperthyroidism-A Proof-of-Concept Trial

CONTEXT

The CD40-CD154 co-stimulatory pathway plays an important role in the pathogenesis of Graves disease (GD) by promoting autoreactive B-cell activation.

OBJECTIVE

Evaluate efficacy and safety of a human, blocking, nondepleting anti-CD40 monoclonal antibody, iscalimab, in hyperthyroid patients with GD.

DESIGN

Open-label, phase II proof-of-concept study.

SETTING

Multicenter.

PATIENTS

Fifteen with GD.

INTERVENTION

Patients received 5 doses of iscalimab at 10 mg/kg intravenously over 12 weeks.

MAIN OUTCOME MEASURES

Thyroid-related hormones and autoantibodies, plasma soluble CD40, free CD40 on B cells, soluble CXCL13, pharmacokinetics, and safety were assessed.

RESULTS

The iscalimab intervention resulted in complete CD40 engagement for up to 20 weeks. A clinical response and biochemical euthyroidism was observed in 7 of 15 (47%) patients. Free and total triiodothyronine and thyroxine normalized in 7 patients who did not receive any rescue medication with antithyroid drugs (ATD), and 2/15 (13.3%) showed normal thyrotropin. Six (40%) patients required ATD. Four of 7 responders relapsed after treatment completion. Serum concentrations of thyrotropin receptor autoantibodies (TSH-R-Ab) significantly declined in all patients (mean 15.3 IU/L vs 4.0 IU/L, 66% reduction; P < 0.001) and TSH-R-Ab levels normalized in 4 (27%). Thyroperoxidase and thyroglobulin autoantibodies significantly decreased in responders. Iscalimab rapidly reduced serum CXCL13 concentrations (P < 0.001). Twelve (80.0%) patients reported at least 1 adverse event (AE). All treatment-related AE were mild or moderate and resolved by end of the study.

CONCLUSION

Iscalimab was generally safe and clinically effective in a subgroup of hyperthyroid GD patients. The potential therapeutic benefit of iscalimab should be further tested.

Immunohistochemical analysis of human orbital tissue in Graves' orbitopathy

PURPOSE

Immunohistochemistry of orbital tissues offers a correlation between the microscopic changes and macroscopic clinical manifestation of Graves' orbitopathy (GO). Summarizing the participation of different molecules will help us to understand the pathogenesis of GO.

METHODS

The pertinent and current literature on immunohistochemistry of human orbital tissue in GO was reviewed using the NCBI PubMed database.

RESULTS

33 articles comprising over 700 orbital tissue samples were included in this review. The earliest findings included the demonstration of HLA-DR and T cell (to a lesser extent B cell) markers in GO orbital tissues. Subsequent investigators further contributed by characterizing cellular infiltration, confirming the presence of HLA-DR and TSHR, as well as revealing the participation of cytokines, growth factors, adhesion molecules and miscellaneous substances. HLA-DR and TSHR are over-expressed in orbital tissues of GO patients. The inflammatory infiltration mainly comprises CD4 + T cells and macrophages. Cytokine profile suggests the importance of Th1 (especially in early active phase) and Th17 immunity in the pathogenesis of GO. Upregulation of proinflammatory/profibrotic cytokines, adhesion molecules and growth factors finally culminate in activation of orbital fibroblasts and perpetuation of orbital inflammation. The molecular status of selected parameters correlates with the clinical presentation of GO.

CONCLUSION

Further investigation is warranted to define precisely the role of different molecules and ongoing search for new players yet to be discovered is also important. Unfolding the molecular mechanisms behind GO will hopefully provide insights into the development of novel therapeutic strategies and optimize our clinical management of the disease.

Comparison of a Novel Homogeneous Cyclic Amp Assay and a Luciferase Assay for Measuring Stimulating Thyrotropin-Receptor Autoantibodies

OBJECTIVE

Stimulating thyrotropin-receptor antibodies (TSAb) cause Graves' disease (GD). We tested a novel homogeneous fluorescent 3',5' cyclic adenine monophosphate (cAMP) assay for the detection of TSAb in a bioassay.

METHODS

Chinese hamster ovary (CHO) cell lines expressing either a chimeric (MC4) or wild-type (WT) TSH-R were incubated with the adenyl cyclase activator forskolin, a human TSAb monoclonal antibody (M22), and with sera from GD patients. Intracellular cAMP levels were measured using a Bridge-It® cAMP assay, and the results were compared with a luciferase-based bioassay.

RESULTS

Both cell lines were stimulated with forskolin concentrations (0.006-200 µM) in a dose-dependent manner. The linear range in the MC4 and WT cells was 0.8-25 and 3.1-50 µM, respectively. Levels of cAMP and luciferase in forskolin-treated MC4 and WT cells were positively correlated (r = 0.91 and 0.84, both p < 0.001). The 50% maximum stimulatory concentration of forskolin was more than 16-fold higher for the CHO-WT cells than the CHO-MC4 cells in the cAMP assay and 4-fold higher in the luciferase assay. Incubation of both cell lines with M22 (0.006-50 ng/mL) resulted in a dose-dependent increase in cAMP levels with linear ranges for the MC4 and WT cells of 0.8-12.5 and 0.2-3.125 ng/mL, respectively. Comparison of cAMP and luciferase levels in M22-treated MC4 and WT cells also showed a positive correlation (r = 0.88, p < 0.001 and 0.75, p = 0.002). A positive correlation was also noted when using patient samples (r = 0.96, p < 0.001) that were all TSH-R-Ab binding assay positive.

CONCLUSION

The novel, rapid, simple-to-perform cAMP assay provides TSAb-mediated stimulatory results comparable to a luciferase-based bioassay.

Glucocorticoids in Graves' orbitopathy: mechanisms of action and clinical application

BACKGROUND

Graves' orbitopathy (GO) is the most frequent extrathyroidal manifestation of the autoimmune Graves' disease. GO significantly impacts quality of life and has a psycho-social morbidity. Inflammation and swelling of the orbital tissue often leads to proptosis, diplopia, and decrease of visual acuity. Due to the inflammatory background of the disease, glucocorticoids (GC) have been used as a first-line treatment for decades.

METHODS

PubMed and MeSH database were searched for original articles, clinical trials, reviews, and meta-analyses published between 1 January 2000 and 31 March 2020 and pertaining to both the mechanism of action and immunological effects of GC as well as to the treatment of GO by GC. The publications were evaluated according to their setting and study design.

RESULTS

GC act through genomic (trans-activation and trans-repression) and rapid non-genomic mechanisms. GC in general, and the intravenous (IV) administration of GC in particular, markedly decrease the activity and number of the most potent antigen-presenting dendritic cells. According to the internationally acknowledged European Thyroid Association Guidelines for the management of GO, weekly IVGC application over 12 weeks is recommended as first-line treatment for patients with active and severe GO. The daily and cumulative dose should be tailored according to clinical severity, for example, 4.5 g of IV methylprednisolone for the inflammatory component versus 7.5 g in the presence of diplopia and severe proptosis. Fast and significant improvements in orbital symptoms and signs are noted in 65-70% of patients. Long-term experience over decades, and worldwide availability at low cost, underline the clinical and therapeutic relevance of GC. Adverse events are rarely severe, dose-dependent, and usually reversible, hence easy to handle by medical investigators. Oral GC application on a daily basis is characterized by high bioavailability but reduced efficacy and increased toxicity.

CONCLUSION

IVGC still represents the standard of care in active/severe GO. Innovative biologicals, like monoclonal antibodies targeting the thyrotropin/Insulin-like growth factor-1 receptors or pro-inflammatory cytokines (e.g., Interleukin-6) should be compared with standard GC treatment with respect to short- and long-term efficacy, safety, costs, and global availability.

Autoimmune polyglandular diseases

Autoimmune polyglandular diseases (APD) are defined as the presence of two autoimmune -induced endocrine failures. With respect to the significant morbidity and potential mortality of APD, the diagnostic objective is to detect APD at an early stage, with the advantage of less frequent complications, effective therapy and better prognosis. This requires that patients at risk be regularly screened for subclinical endocrinopathies prior to clinical manifestation. Regarding the time interval between manifestation of first and further endocrinopathies, regular and long-term follow-up is warranted. Quality of life and psychosocial status are poor in APD patients and involved relatives. Familial clustering is high in patients with APD. Considering the high incidence of one or more endocrinopathies in first-degree relatives of patients with APD, family members should be regularly screened since they may also develop autoimmune endocrinopathies. Multidisciplinary management of these multiplex families in specialized centers is warranted.

Immunotherapies for thyroid eye disease

PURPOSE OF REVIEW

Thyroid eye disease is a complex autoimmune disorder which causes substantial morbidity. It can result in orbital disfigurement, double vision, and visual loss. Consequently, it has a substantial negative effect on quality of life, mental health, and socioeconomic status. Most signs and symptoms of thyroid eye disease (TED) can be explained by the expansion of the orbital contents. Steroids are the mainstay of treatment in TED. However, recurrence may occur once steroids are withdrawn. Furthermore, in most cases, normal orbital anatomy is not restored, and skilled rehabilitative surgery is required to reduce disfigurement, double vision, and to preserve vision. Therefore, novel, causal, and more efficacious treatment strategies are warranted.

RECENT FINDINGS

In the last decade, the pathophysiology of TED has also been revised with the identification of new potential therapeutic targets. Recent clinical trials have shown that considerable benefit may be derived from the addition of antiproliferative agents (e.g., mycophenolate sodium) in preventing deterioration after steroid cessation. In addition, targeted biologic therapies have shown promise, including teprotumumab (anti-IGFR) which appears to substantially reduce proptosis, rituximab (anti-CD20) which reduces inflammation and tocilizumab (anti-IL-6) which potentially benefits both of these parameters.

SUMMARY

This short review summarizes the recent research developments in this area.

High Titers of Thyrotropin Receptor Antibodies Are Associated With Orbitopathy in Patients With Graves Disease

CONTEXT

Serum TSH receptor autoantibody (TSH-R-Ab) is a biomarker of Graves disease (GD). Studies have shown that the levels of this TSH-R-Ab have clinical significance.

OBJECTIVE

To differentiate between thyroidal GD only and Graves orbitopathy (GD + GO).

DESIGN

Controlled, follow-up study.

SETTING

Academic tertiary referral center for GD + GO.

SUBJECTS

Sixty patients with GD, GD + GO, and controls.

INTERVENTION

Serial serum dilution analyses with six automated, ELISA, and cell-based assays for TSH-R-Ab.

MAIN OUTCOME MEASURE

Differentiation among GD phenotypes.

RESULTS

All undiluted samples of hyperthyroid-untreated GD patients were positive with the six assays but became negative at dilution 1:9 in four of six assays. In contrast, all undiluted samples of hyperthyroid-untreated GD + GO patients remained positive up to dilution 1:81, P < 0.001. At high dilutions 1:243, 1:729, 1:2187, and 1:6561, the rate of stimulating TSH-R-Ab positivity in the bioassay for GD + GO patients was 75%, 35%, 5%, and 0%, respectively (all P < 0.001). The five ELISA and/or automated assays confirmed this marked difference of anti-TSH-R-Ab detection between GD-only and GD + GO. In comparison, the baseline-undiluted samples of GD vs GD + GO showed an overlap in the ranges of TSH-R-Ab levels. Subsequent to 12-month methimazole treatment, samples from euthyroid GD + GO patients were still TSH-R-Ab positive at the high dilution of 1:243. In contrast, all GD samples were negative already at dilution 1:3. A GD patient with TSH-R-Ab positivity at dilution 1:729 developed de novo GO.

CONCLUSIONS

TSH-R-Ab titers, as determined by dilution analysis, significantly differentiate between GD and GD + GO.

Thyrotropin Receptor Blocking Antibodies

Autoantibodies (Ab) against the thyroid-stimulating hormone receptor (TSHR) are frequently found in autoimmune thyroid disease (AITD). Autoantibodies to the TSHR (anti-TSHR-Ab) may mimic or block the action of TSH or be functionally neutral. Measurement of anti-TSHR-Ab can be done either via competitive-binding immunoassays or with functional cell-based bioassays. Antibody-binding assays do not assess anti-TSHR-Ab functionality, but rather measure the concentration of total anti-TSHR binding activity. In contrast, functional cell-based bioassays indicate whether anti-TSHR-Ab have stimulatory or blocking activity. Historically bioassays for anti-TSHR-Ab were research tools and were used to study the pathophysiology of Graves' disease and Hashimoto's thyroiditis. In the past, bioassays for anti-TSHR-Abs were laborious and time-consuming and varied widely in performance from laboratory to laboratory. Recent advances in the development of cell-based assays, including the application of molecular engineering, have led to significant improvements that have enabled bioassays to be employed routinely in clinical laboratories. The prevalence and functional significance of TSHR blocking autoantibodies (TBAb) in autoimmune hypothyroidism has been less well investigated compared to TSHR stimulating Ab. There is an increasing body of data, however, that demonstrate the clinical utility and relevance of TBAb, and thus the importance of TBAb bioassays, in the diagnosis and management of patients with AITD. In the present review, we summarize the different methods used to measure TBAb, and discuss their prevalence and clinical relevance.

Stimulatory TSH-Receptor Antibodies and Oxidative Stress in Graves Disease

CONTEXT

We hypothesized that TSH-receptor (TSHR) stimulating antibodies (TSAbs) are involved in oxidative stress mechanisms in patients with Graves disease (GD).

METHODS

Nicotinamide adenine dinucleotide phosphate oxidase, isoform 2 (NOX2); oxidative parameters; and oxidative burst were measured in serum, urine, and whole blood from patients with GD and control subjects. Superoxide production was investigated in human embryonic kidney (HEK)-293 cells stably overexpressing the TSHR. Lipid peroxidation was determined by immunodot-blot analysis for protein-bound 4-hydroxy-2-nonenal (4-HNE) in human primary thyrocytes and HEK-293-TSHR cells.

RESULTS

Serum NOX2 levels were markedly higher in hyperthyroid untreated vs euthyroid treated patients with GD, hyperthyroid patients with toxic nodular goiter, and euthyroid healthy control subjects (all P < 0.0001). Urine oxidative parameters were increased in patients with GD vs patients with toxic goiter (P < 0.01) and/or control subjects (P < 0.001). The maximum of the zymosan A- and phorbol 12,13-dibutyrate-induced respiratory burst of leukocytes was 1.5-fold higher in whole blood from hyperthyroid patients with GD compared with control subjects (P < 0.001 and P < 0.05). Monoclonal M22 TSAbs stimulated cAMP (HEK cells) in a dose-dependent manner. M22 (P = 0.0082), bovine TSH (P = 0.0028), and sera of hyperthyroid patients with GD (P < 0.05) increased superoxide-specific 2-hydroxyethidium levels in HEK-293 TSHR cells after 48-hour incubation vs control subjects. In contrast, triiodothyronine (T3) did not affect reactive oxygen species (ROS) production. In primary thyrocytes, the 4-HNE marker was higher in patients with GD vs control subjects at 6 and 48 hours (P = 0.02 and P = 0.04, respectively). Further, after 48-hour incubation of HEK-293 TSHR cells with patient sera, 4-HNE was higher in patients with untreated GD compared with control subjects (P < 0.05).

CONCLUSIONS

Monoclonal M22 and polyclonal serum TSAbs augment ROS generation and/or induce lipid peroxidation.