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

Stimulating thyrotropin receptor antibodies in early pregnancy

OBJECTIVES

Thyrotropin-receptor antibodies (TRAb) are used to diagnose Graves' hyperthyroidism in pregnant women. Bioassays provide a measure of thyrotropin-receptor stimulatory antibodies (TSI) specifically. The objective was to measure TSI in pregnant women for establishment of a pregnancy-specific cut-off and comparison with immunoassay measurements of TRAb.

METHODS

The retrospective Danish study was performed within the North Denmark Region Pregnancy Cohort (2011-2015) that includes stored biobank samples from early pregnancy (median week 10) with immunoassay measurements of thyroid function parameters and TRAb. TSI were measured in the same samples using the Turbo TSI bioassay (Quidel/Ortho-Clinical Diagnostics) with a recommended cut-off of 0.0241 IU/L in non-pregnant adults. A pregnancy-specific TSI cut-off (95-percentile) was established using Regression on Order Statistics.

RESULTS

The established TSI cut-off was 0.0418 IU/L (95 % CI: 0.0417-0.0419). Among women with early pregnancy hyperthyroidism (n=438), 43 women (9.8 %) were TSI positive using the established cut-off, and these women had lower TSH (median 0.008 mIU/L) compared to women with TSI levels below 0.0241 (median TSH 0.040 mIU/L) or in the range from 0.0241 to 0.0418 (median TSH 0.033 mIU/L). Among the 438 women with early pregnancy hyperthyroidism, 22 women were positive for TSI and TRAb, 388 were negative for both, and 28 women were positive for either TSI or TRAb.

CONCLUSIONS

This is the first study on TSI measurements in a large cohort of early pregnant women. A pregnancy-specific cut-off for TSI was established and agreement in the classification with immunoassay measurements of TRAb was seen in 94 % of cases.

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.

Molecular Biomarkers in Thyroid Eye Disease: A Literature Review

PURPOSE

Thyroid eye disease (TED) is the most common extrathyroidal manifestation of Graves disease. Patients may be severely affected with eyelid retraction, exophthalmos, diplopia, pain, and threatened vision. Autoantibodies against thyroid-stimulating hormone receptor and insulin-like growth factor 1 receptor have shown associations with pathophysiological and clinical traits. Autoantibodies against thyroid-stimulating hormone receptor is in current clinical use as biomarker, but not with unambiguous diagnostic performance. A biomarker with high diagnostic accuracy and/or prognostic capability would be of immense value in diagnosing TED, especially in subclinical cases or when TED precedes the thyroid dysfunction. This article is a literature review on molecular biomarkers of TED.

METHODS

A literature search was performed using PubMed and Embase. Studies on molecular biomarkers in blood, tear fluid, and urine were included in the review.

RESULTS

Forty-six papers were included, of which 30, 14, and 2 studies on biomarkers in blood, tears, and urine, respectively. Fourteen of the papers evaluated the diagnostic performance of various biomarkers, 12 in blood and 2 in tears. Most studies evaluated single biomarkers, but 3 tested a panel of several markers. Except for autoantibodies against thyroid-stimulating hormone receptor, the reported diagnostic performances for the biomarkers were not confirmed in independent cohorts. In 32 studies, no or insufficient performance data were given, but the findings indicated involvement of various biologic mechanisms in TED including inflammation, oxidative stress, fibrosis, lipid metabolism, and ocular surface microflora.

CONCLUSIONS

Currently, serum autoantibodies against thyroid-stimulating hormone receptor is the only molecular biomarker with clinical utility in patients with TED. Several potential biomarkers have been investigated, and particularly panels of multiple biomarkers in tears are promising. To improve patient care, biomarkers in TED should be studied further.

The curious case of Prevotella copri

Prevotella copri is an abundant member of the human gastrointestinal microbiome, whose relative abundance has curiously been associated with positive and negative impacts on diseases, such as Parkinson's disease and rheumatoid arthritis. Yet, the verdict is still out on the definitive role of P. copri in human health, and on the effect of different diets on its relative abundance in the gut microbiome. The puzzling discrepancies among P. copri studies have only recently been attributed to the diversity of its strains, which substantially differ in their encoded metabolic patterns from the commonly used reference strain. However, such strain differences cannot be resolved by common 16S rRNA amplicon profiling methods. Here, we scrutinize P. copri, its versatile metabolic potential, and the hypotheses behind the conflicting observations on its association with diet and human health. We also provide suggestions for designing studies and bioinformatics pipelines to better research P. copri.

Comparison of two different TSH-receptor antibody assays: A clinical practice study

Background

Graves' disease (GD) is caused by the production of TSH-receptor (TSHR) stimulating auto-antibodies. Over the years various TSHR-antibody (TRAb) detection assays have been developed. Most clinical laboratories use competitive TSH-binding inhibitory immunoglobulin (TBII) assays, which measure the total amount of stimulating and blocking auto-antibodies. Selective detection of TSHR stimulating auto-antibodies (TSI) was previously only possible with functional cell-based bioassays. However, more recently an automated bridge-based binding assay to more specifically measure TSI has become available. The aim of our study was to compare the third-generation automated competitive immunoassay (TBII) with the automated bridge immunoassay (TSI) in clinical practice in an academic thyroid expert center.

Methods

A retrospective study in 356 patients with Graves' disease, Graves orbitopathy (GO), and other (thyroid) disease treated in an academic thyroid center was performed. All samples were analyzed for TBII and TSI. For both assays, sensitivity, specificity, positive predictive value (PVV), negative predictive value (NPV) and diagnostic odds ratios were calculated using different cut-offs for negativity.

Results

Using the provided cut-off, the overall sensitivity appeared similar between TBII and TSI, but TSI showed higher overall specificity, PPV, NPV and diagnostic odds ratio. Using two or three times the cut-off for negativity resulted in a decrease in sensitivity, but an increase in specificity and PPV, which was most pronounced for the TBII-assay. Analysis in a subgroup of newly diagnosed treatment naïve GD/GO patients also revealed overall favorable results for the TSI-assay. Increasing the cut-off for negativity resulted in increased specificity for both assays, with similar results using two or three times the cut-off. Most patients with concordant positive results for TBII and TSI suffered from GD or GD + GO (n = 110, 95.6 %), while patients negative for both TBII and TSI mostly suffered from other (thyroid) disease (n = 143, 77.3 %). From patients with positive TBII but negative TSI only 42.1 % had GD/GO (n = 16), whereas 57.9 % (n = 22) had other (thyroid) disease. In contrast, 88.9 % of patients with positive TSI but negative TBII had GD/GO (n = 16), whereas 11.1 % (n = 2) had other (thyroid) disease.

Conclusion

In our academic thyroid center, the diagnostic performance of the TSI-assay outperformed the TBII-assay. Using a higher cut-off value for negativity can be helpful in assessing clinical relevance.

The phenotype of Graves' orbitopathy is associated with thyrotropin receptor antibody levels

PURPOSE

Graves' orbitopathy (GO) is a specific inflammatory disorder of the orbit characterized by a highly heterogeneous clinical phenotype. The role of thyrotropin receptor antibodies (TSH-R-Ab) has been widely researched, however there is still no evidence that these antibodies have a direct pathogenic role in this pathology. The aim of this study was to examine their relation to the individual clinical features of GO.

METHODS

Ninety-one consecutive patients with GO were recruited. Total antibody concentration (TSH-R binding inhibitory immunoglobulins, TBII) and their functional activity (stimulating TSH-R-Ab, TSAb) were measured using binding immunoassay and cell-based bioassay, respectively.

RESULTS

Both TSAb and TBII levels were significantly associated to the clinical parameters of GO activity. TSAb was a more sensitive serological marker compared to TBII pertaining to eyelid retraction and edema, proptosis, extra-orbital muscle disorders, diplopia, irritable eye symptoms, and photophobia. TSAb, but not TBII, was a significant predictive marker of conjunctival redness, chemosis, caruncle/plica inflammation, eye irritation, and orbital pain, (odds ratio: 3.096, p = 0.016; 5.833, p = 0.009; 6.443, p = 0.020; 3.167, p = 0.045; 2.893, p = 0.032; versus 2.187, p = 0.093; 2.775, p = 0.081; 3.824, p = 0.055; 0.952, p = 0.930; 2.226, p = 0.099, respectively). Neither TSAb nor TBII correlated with the level of proptosis (ρ = 0.259, p = 0.090, and ρ = 0.254, p = 0.104, respectively), however rising TSAb levels were strongly associated to the level of proptosis.

CONCLUSIONS

TSH-R-Ab were significantly associated with GO's phenotype. Especially TSAb, as a sensitive and predictive serological biomarker, can improve diagnosis and management of GO.

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.

Pathophysiology of thyroid-associated orbitopathy

Thyroid-associated orbitopathy, the most common extrathyroidal manifestation of Graves' disease, is characterized by orbital inflammatory infiltration and activation of orbital fibroblasts, which mediates de novo adipogenesis, excessive production of hyaluronan, myofibroblast differentiation and ultimately tissue fibrosis. Interactions among T cells, B cells, and orbital fibroblasts result in their activation and perpetuation of orbital inflammation as well as tissue remodelling. T helper 17 cells belong to a newly identified pathogenic CD4+ T cell subset which possesses prominent pro-inflammatory and profibrotic capabilities. Thyroid stimulating hormone receptor/insulin-like growth factor-1 receptor crosstalk and the downstream signalling pathways of both receptors represent the major mechanisms leading to activation of orbital fibroblasts. Thyroid stimulating hormone receptor autoantibody is the disease specific biomarker of great clinical relevance and utility. There is growing evidence that oxidative stress, gut microbiome and epigenetics also play a role in the pathogenesis and their manipulation may represent novel therapeutic strategies.

Recurrence risk of autoimmune thyroid and endocrine diseases

BACKGROUND AND OBJECTIVE

The recurrence risk ratio (λ) expresses the risk ratio of index patients' first-degree relatives developing a disease as compared to the general population and is a quantitative measure of the genetic contribution to the disease. This paper offers the results of a specialized center as well as a review of the pertinent literature.

METHODS

Data from 3315 consecutive subjects followed at an ORPHAN academic tertiary referral expert center for endocrine autoimmunity as well as 419 unrelated German families were collected. λ was assessed based on 806 well-documented subjects, 299 index patients with autoimmune glandular (AIGD) and non-endocrine diseases and 507 of their first-degree relatives (328 children, 179 siblings).

RESULTS

As many as 36% of relatives of patients with autoimmune diseases (AID) were affected by various autoimmune conditions. Twenty-five percent and 23% of all relatives had an AIGD or an autoimmune thyroid disease (AITD), respectively. Furthermore, 29% and 25% of relatives of index cases with polyglandular (PGA) and monoglandular (MGA) autoimmunity were affected. The recurrence risk for AITD was increased 16-fold in both children and siblings compared to the general population (λ, 95% CI 16, 11-21 and 16, 12-19, respectively). Furthermore, λ for AITD/AIGD was 21.62 (95% CI 14.17-30.69)/17.57 (11.80-24.36) and 13.48 (8.42-20.52)/10.68 (6.76-16.02) for siblings of patients with PGA and MGA, respectively. Overall, a strong genetic component for AITD and AIGD with a significant genetic impact on the development of PGA was demonstrated.

CONCLUSION

These novel results strongly recommend the screening for AITD and AIGD in children and siblings of index patients with AITD.

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.

Thyroid autoantibodies

Thyroid-stimulating hormone (TSH) receptor antibody (TSH-R-Ab or TRAb) testing plays a pivotal role in arriving at the aetiological diagnosis in patients with thyrotoxicosis. A positive test establishes the diagnosis of Graves' disease (GD) while a negative result in conjunction with imaging studies supports other possible aetiologies. In patients with GD, TRAb levels at diagnosis and at the time of withdrawal of antithyroid drugs can identify patients who are unlikely to achieve remission and guide clinical management decisions. We provide an algorithm that incorporates TRAb in the decision-making process for the management of thyrotoxicosis. The utility of TRAb in predicting the risk of fetal and neonatal thyroid dysfunction is established and widely accepted in guidelines. TRAb may also help in the diagnosis of Graves' orbitopathy, especially in euthyroid or hypothyroid patients and its role in guiding its management is evolving as a useful adjunct to the clinical parameters used in making therapeutic decisions.Anti-thyroid peroxidase antibodies (TPOAb) and anti-thyroglobulin antibodies (TgAb) indicate thyroid autoimmunity. The most common use of TPOAb is to identify patients at a higher risk of progression to treatment-requiring hypothyroidism. They also aid the diagnosis of immune thyroiditis and Hashimoto's encephalopathy. Thyroglobulin measurement is used to help guide differentiated thyroid cancer treatment. TgAb is used as an accompanying test with thyroglobulin measurement as its presence can interfere with the thyroglobulin assay. A negative TgAb result reduces the likelihood of, but does not exclude, interference with thyroglobulin assay.

A review of TSHR- and IGF-1R-related pathogenesis and treatment of Graves' orbitopathy

Graves' orbitopathy (GO) is an organ-specific autoimmune disease, but its pathogenesis remains unclear. There are few review articles on GO research from the perspective of target cells and target antigens. A systematic search of PubMed was performed, focusing mainly on studies published after 2015 that involve the role of target cells, orbital fibroblasts (OFs) and orbital adipocytes (OAs), target antigens, thyrotropin receptor (TSHR) and insulin-like growth factor-1 receptor (IGF-1R), and their corresponding antibodies, TSHR antibodies (TRAbs) and IGF-1R antibodies (IGF-1R Abs), in GO pathogenesis and the potentially effective therapies that target TSHR and IGF-1R. Based on the results, OFs may be derived from bone marrow-derived CD34+ fibrocytes. In addition to CD34+ OFs, CD34- OFs are important in the pathogenesis of GO and may be involved in hyaluronan formation. CD34- OFs expressing Slit2 suppress the phenotype of CD34+ OFs. β-arrestin 1 can be involved in TSHR/IGF-1R crosstalk as a scaffold. Research on TRAbs has gradually shifted to TSAbs, TBAbs and the titre of TRAbs. However, the existence and role of IGF-1R Abs are still unknown and deserve further study. Basic and clinical trials of TSHR-inhibiting therapies are increasing, and TSHR is an expected therapeutic target. Teprotumumab has become the latest second-line treatment for GO. This review aims to effectively describe the pathogenesis of GO from the perspective of target cells and target antigens and provide ideas for its fundamental treatment.

Recent advances in graves ophthalmopathy medical therapy: a comprehensive literature review

Graves ophthalmopathy (GO), which occurs in autoimmune thyroid disease, can reduce patients' quality of life due to its impact on visual function, physical appearance, and emotional health. Corticosteroids have been the first-line treatment for GO. More recently, the pathogenesis of GO has made significant progress. Various targeting biological agents and immunosuppressive agents make GO management more promising. Fully understanding GO pathogenesis and precise clinical management are beneficial for the prognosis of patients. Therefore, we conducted a comprehensive review of the medical management of GO and summarized research developments to highlight future research issues.

A systematic review of multimodal clinical biomarkers in the management of thyroid eye disease

Thyroid Eye Disease (TED) is an autoimmune disease that affects the extraocular muscles and periorbital fat. It most commonly occurs with Graves' Disease (GD) as an extrathyroidal manifestation, hence, it is also sometimes used interchangeably with Graves' Ophthalmopathy (GO). Well-known autoimmune markers for GD include thyroid stimulating hormone (TSH) receptor antibodies (TSH-R-Ab) which contribute to hyperthyroidism and ocular signs. Currently, apart from radiological investigations, detection of TED is based on clinical signs and symptoms which is largely subjective, with no established biomarkers which could differentiate TED from merely GD. We evaluated a total of 28 studies on potential biomarkers for diagnosis of TED. Articles included were published in English, which investigated clinical markers in tear fluid, orbital adipose-connective tissues, orbital fibroblasts and extraocular muscles, serum, thyroid tissue, as well as imaging biomarkers. Results demonstrated that biomarkers with reported diagnostic power have high sensitivity and specificity for TED, including those using a combination of biomarkers to differentiate between TED and GD, as well as the use of magnetic resonance imaging (MRI). Other biomarkers which were upregulated include cytokines, proinflammatory markers, and acute phase reactants in subjects with TED, which are however, deemed less specific to TED. Further clinical investigations for these biomarkers, scrutinising their specificity and sensitivity on a larger sample of patients, may point towards selection of suitable biomarkers for aiding detection and prognosis of TED in the future.

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.

Clinical value of functional thyrotropin receptor antibodies in Serbian patients with Graves' orbitopathy

PURPOSE

Thyrotropin receptor autoantibodies (TSH-R-Ab) are heterogeneous in their biological function and play a significant role in the pathophysiology of both Graves' disease and Graves' orbitopathy (GO). The clinical significance and utility of determining functional TSH-R-Ab in a Serbian collective were evaluated.

METHODS

91 consecutive patients with GO were included in this study. Total TSH-R-Ab concentration, referred to as TSH-R binding inhibitory immunoglobulins (TBII) was detected using a competitive-binding immunoassay. Stimulating and blocking TSH-R-Ab (TSAb and TBAb) were measured with cell-based bioassays.

RESULTS

Stimulating TSAb activity and TBII positivity were detected in 85 of 91 (93.4%) and 65 of 91 (71.4%) patients with GO (P < 0.001). Blocking TBAb activity was observed in only one patient who expressed dual stimulating and blocking TSH-R-Ab activity. The sensitivity rates for differentiating between clinically active versus inactive and mild versus moderate-to-severe GO were 100% and 100% for TSAb, respectively. In contrast, these were 82% and 87% only for TBII. Seven of eight (87.5%) and one of eight (12.5%) euthyroid patients with GO were TSAb and TBII positive, respectively (P < 0.031). TSAb serum levels significantly predicted GO activity compared to TBII (odds ratio, OR, 95%CI: 3.908, 95%CI 1.615-9.457, P = 0.003; versus 2.133, 0.904-5.032, P = 0.084, univariate analysis; and OR 4.341, 95%CI 1.609-11.707, P = 0.004; versus 2.337, 0.889-6.145, P = 0.085 multivariate analysis).

CONCLUSION

Stimulating TSAb are highly prevalent in patients with GO and show superior clinical characteristics and predictive potential compared to the traditionally used TBII.

Graves' Autoantibodies Exhibit Different Stimulating Activities in Cultures of Thyrocytes and Orbital Fibroblasts Not Reflected by Clinical Assays

Background: The pathogenesis of Graves' hyperthyroidism (GH) and associated Graves' orbitopathy (GO) appears to involve stimulatory autoantibodies (thyrotropin receptor [TSHR]-stimulating antibodies [TSAbs]) that bind to and activate TSHRs on thyrocytes and orbital fibroblasts. In general, measurement of circulating TSHR antibodies by clinical assays correlates with the status of GH and GO. However, most clinical measurements of TSHR antibodies use competitive binding assays that do not distinguish between TSAbs and antibodies that bind to but do not activate TSHRs. Moreover, clinical assays for TSAbs measure stimulation of only one signaling pathway, the cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway, in engineered cells that are not thyrocytes or orbital fibroblasts. We determined whether measuring TSAbs by a cAMP-PKA readout in engineered cells accurately reveals the efficacies of stimulation by these antibodies on thyrocytes and orbital fibroblasts. Methods: We measured TSAb stimulation of normal human thyrocytes and orbital fibroblasts from patients with GO in primary cultures in vitro. In thyrocytes, we measured secretion of thyroglobulin (TG) and in orbital fibroblasts secretion of hyaluronan (hyaluronic acid [HA]). We also measured stimulation of cAMP production in engineered TSHR-expressing cells in an assay similar to clinical assays. Furthermore, we determined whether there were differences in stimulation of thyrocytes and orbital fibroblasts by TSAbs from patients with GH alone versus from patients with GO understanding that patients with GO have accompanying GH. Results: We found a positive correlation between TSAb stimulation of cAMP production in engineered cells and TG secretion by thyrocytes as well as HA secretion by orbital fibroblasts. However, TSAbs from GH patients stimulated thyrocytes more effectively than TSAbs from GO patients, whereas TSAbs from GO patients were more effective in activating orbital fibroblasts than TSAbs from GH patients. Conclusions: Clinical assays of stimulation by TSAbs measuring activation of the cAMP-PKA pathway do correlate with stimulation of thyrocytes and orbital fibroblasts; however, they do not distinguish between TSAbs from GH and GO patients. In vitro, TSAbs exhibit selectivity in activating TSHRs since TSAbs from GO patients were more effective in stimulating orbital fibroblasts and TSAbs from GH patients were more effective in stimulating thyrocytes.

SENSITIVITY OF THREE THYROTROPIN RECEPTOR ANTIBODY ASSAYS IN THYROID-ASSOCIATED ORBITOPATHY

Background

Thyrotropin receptor autoantibodies (TSH-RAb) are indispensable biomarkers in the laboratory assessment of thyroid-associated orbitopathy (TAO). Clinical sensitivity of three different assays for TSH-R-Ab determination was evaluated in patients with TAO.

Methods

87 consecutive TAO patients were enrolled and their serum samples analyzed in parallel with three assays. An ECLIA competitive binding and a chemiluminescent bridge immunoassay were used to measure total and binding TSH-R-Ab concentration, while their functional activity was determined using a stimulatory TSH-R-Ab (TSAb) cellbased bioassay.

Results

Compared to the two binding assays (ECLIA p<0.001, bridge p=0.003), the TSAb bioassay was more sensitive pertaining to the positive detection of TSH-R-Ab in TAO patients. No difference (p=0.057) was noted between the ECLIA and bridge assays regarding sensitivity rate. All patients with active and/or moderate-to-severe TAO tested positive in the TSAb bioassay (100% and 100%, respectively), while the positivity rates for bridge and ECLIA binding assays were 89.7% and 82.1% for active TAO, and 90.2% and 86.3% for severe TAO, respectively. Negative predictive values of the bioassay, bridge, and ECLIA assays were 100%, 75%, and 71%, respectively for active TAO, and 100%, 86%, and 71%, respectively for moderate-to-severe TAO. The superiority of the bioassay was most prominent in euthyroid (ET) TAO. Positivity rates of the TSAb bioassay, bridge and ECLIA binding assays were 89.6%, 75%, and 64.6%, respectively for inactive TAO; 86.1%, 69.4%, and 52.8%, respectively for mild TAO; 87.5%, 62.5%, and 12.5%, respectively for euthyroid TAO. The bridge assay correlated better with the ECLIA binding assay (r=0.893, p<0.001), compared to the bioassay (r=0.669, p<0.001).

Conclusions

In patients with TAO of various activity and severity, the TSAb bioassay demonstrates a superior clinical performance compared to both ECLIA and bridge binding assays.

Identification of Two Different Phenotypes of Patients with Amiodarone-Induced Thyrotoxicosis and Positive Thyrotropin Receptor Antibody Tests

Introduction: Serum thyrotropin (TSH) receptor antibodies (TRAbs) are occasionally found in patients with amiodarone-induced thyrotoxicosis (AIT), and usually point to a diagnosis of type 1 AIT (AIT1) due to Graves' disease (GD). However, the TRAb role and function in AIT have not been clarified. Methods: A retrospective cohort study of 309 AIT patients followed at a single academic center over a 30-year period. AIT TRAb-positive patients (n = 21, 7% of all cases) constituted the study group; control groups consisted of type 2 AIT (AIT2) TRAb-negative patients (n = 233), and 100 non-AIT patients with GD. Clinical and biochemical data at diagnosis and during the course of disease were compared. Histological samples of patients who had total thyroidectomy were reviewed. Stored serum samples were used for a functional assay of TRAb class G immunoglobulins (IgGs) in Chinese hamster ovary (CHO) cells stably transfected with complementary DNA encoding for the TSH receptor. Results: TRAb-positive patients were grouped according to color flow Doppler sonography, radioactive iodine thyroid uptake, and duration of amiodarone therapy before thyrotoxicosis in type 1 (n = 9, 43%; TRAb1) or type 2 (n = 12, 57%; TRAb2) AIT. TRAb1 patients had clinical and biochemical features indistinguishable from GD controls, and were responsive to methimazole. Conversely, TRAb2 patients had clinical features similar to AIT2 controls, and were responsive to glucocorticoids, but not to methimazole. The CHO cell functional assay demonstrated that TRAb1 IgGs had a stimulatory effect on cyclic AMP production, which was absent in TRAb2 IgGs. Pathology in TRAb1 showed hyperplastic thyroid follicles and mild lymphocyte infiltration, reflecting thyroid stimulation. On the contrary, TRAb2 samples revealed follicle destruction, macrophage infiltration, and sometimes fibrosis, consistent with a destructive process. Conclusions: Almost 60% of TRAb-positive AIT patients had a destructive thyroiditis. TRAb-positive tests in AIT patients do thus not necessarily imply a diagnosis of GD and AIT1, and should be evaluated in the clinical and biochemical setting of each AIT patient and confirmed by measuring thyroid-stimulating immunoglobulins.

Teprotumumab in Thyroid-Associated Ophthalmopathy: Rationale for Therapeutic Insulin-Like Growth Factor-I Receptor Inhibition

Thyroid-associated ophthalmopathy (TAO) is an autoimmune component of Graves' disease for which no currently available medical therapy provides reliable and safe benefit. Based on insights generated experimentally over the past several decades, the insulin-like growth factor-I receptor (IGF-IR) has been implicated in the pathogenesis of TAO. Furthermore, an IGF-IR inhibitor, teprotumumab, has emerged from 2 clinical trials as a promising treatment for active, moderate to severe TAO. This brief review intends to provide an overview of the rationale underlying the development of teprotumumab for this disease. It is possible that teprotumumab will soon take its place in our therapeutic armamentarium for active TAO.

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.

Predictive Factors for Changes in Quality of Life after Steroid Treatment for Active Moderate-to-Severe Graves' Orbitopathy: A Prospective Trial

OBJECTIVES

To investigate the predictive factors for changes in the quality of life (GO-QoL) of patients with Graves' orbitopathy (GO) prior to and after specific treatment.

METHODS

A prospective follow-up study was conducted at an academic tertiary referral orbital center with a joint thyroid-eye clinic on 100 consecutive patients with GO. Before and after the standard 12-week course of weekly intravenous methylprednisolone (cumulative dose 4.5 g), the GO-QoL questionnaire provided by the European Group on Graves' Orbitopathy (EUGOGO) was completed. Endocrine and ophthalmic assessments were performed at each visit.

RESULTS

All patients were biochemically euthyroid and untreated for GO at baseline and presented with active and moderate-to-severe disease. Both GO-QoL subscales (visual functioning [VF] and appearance [AP]) significantly increased after immunosuppressive therapy and showed a sustained improvement for 6 months. At baseline, demographic variables (sex, age, and smoking) influenced QoL in the stepwise linear regression (p < 0.01, adjusted R ² = 0.24 for VF and p < 0.01, adjusted R ² = 0.21 for AP). In contrast, 6 months after treatment, the improved QoL was now exclusively associated with ophthalmic parameters (p < 0.01, adjusted R ² = 0.47 for VF; p < 0.01, adjusted R ² = 0.23 for AP).

CONCLUSIONS

Predictive factors for GO-QoL differed not only between the 2 subscales but also before and after the first treatment 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.

Management of Graves Thyroidal and Extrathyroidal Disease: An Update

CONTEXT

Invited update on the management of systemic autoimmune Graves disease (GD) and associated Graves orbitopathy (GO).

EVIDENCE ACQUISITION

Guidelines, pertinent original articles, systemic reviews, and meta-analyses.

EVIDENCE SYNTHESIS

Thyrotropin receptor antibodies (TSH-R-Abs), foremost the stimulatory TSH-R-Abs, are a specific biomarker for GD. Their measurement assists in the differential diagnosis of hyperthyroidism and offers accurate and rapid diagnosis of GD. Thyroid ultrasound is a sensitive imaging tool for GD. Worldwide, thionamides are the favored treatment (12-18 months) of newly diagnosed GD, with methimazole (MMI) as the preferred drug. Patients with persistently high TSH-R-Abs and/or persistent hyperthyroidism at 18 months, or with a relapse after completing a course of MMI, can opt for a definitive therapy with radioactive iodine (RAI) or total thyroidectomy (TX). Continued long-term, low-dose MMI administration is a valuable and safe alternative. Patient choice, both at initial presentation of GD and at recurrence, should be emphasized. Propylthiouracil is preferred to MMI during the first trimester of pregnancy. TX is best performed by a high-volume thyroid surgeon. RAI should be avoided in GD patients with active GO, especially in smokers. Recently, a promising therapy with an anti-insulin-like growth factor-1 monoclonal antibody for patients with active/severe GO was approved by the Food and Drug Administration. COVID-19 infection is a risk factor for poorly controlled hyperthyroidism, which contributes to the infection-related mortality risk. If GO is not severe, systemic steroid treatment should be postponed during COVID-19 while local treatment and preventive measures are offered.

CONCLUSIONS

A clear trend towards serological diagnosis and medical treatment of GD has emerged.

Is There Evidence for IGF1R-Stimulating Abs in Graves' Orbitopathy Pathogenesis?

In this review, we summarize the evidence against direct stimulation of insulin-like growth factor 1 receptors (IGF1Rs) by autoantibodies in Graves' orbitopathy (GO) pathogenesis. We describe a model of thyroid-stimulating hormone (TSH) receptor (TSHR)/IGF1R crosstalk and present evidence that observations indicating IGF1R's role in GO could be explained by this mechanism. We evaluate the evidence for and against IGF1R as a direct target of stimulating IGF1R antibodies (IGF1RAbs) and conclude that GO pathogenesis does not involve directly stimulating IGF1RAbs. We further conclude that the preponderance of evidence supports TSHR as the direct and only target of stimulating autoantibodies in GO and maintain that the TSHR should remain a major target for further development of a medical therapy for GO in concert with drugs that target TSHR/IGF1R crosstalk.

Chromogranin Serves as Novel Biomarker of Endocrine and Gastric Autoimmunity

CONTEXT

The glycoprotein chromogranin A (CgA) is expressed by endocrine and neuroendocrine cells. High levels of serum CgA serve as markers of neuroendocrine tumors (NET), but its role in autoimmunity has not been assessed.

OBJECTIVE

To investigate CgA utility as a marker of endocrine autoimmunity.

METHODS

CgA serum levels were evaluated in 807 consecutive unselected participants (cross-sectional study) with the time-resolved amplified cryptate emission technology.

RESULTS

Serum CgA concentrations were increased in 66%, 39%, 38%, and 24% of patients with NET, type 1 diabetes (T1D), autoimmune gastritis (AG) and autoimmune polyendocrinopathy (AP), respectively. Compared with healthy participant controls (C), the odds of positive CgA measurement were up to 28 times higher in the disease groups. In detail, the odds ratios (ORs) for positive CgA levels were 27.98, 15.22, 7.32 (all P < 0.0001) and 3.89 (P = 0.0073) in patients with NET, T1D, AG, and AP, respectively. In AG, CgA and serum gastrin correlated positively (r = 0.55; P < 0.0001). The area under the receiver operating characteristic curve to predict AG was higher for parietal cell antibody (PCA) positivity than for CgA (0.84 vs 0.67; P < 0.0001). However, in combination with PCA and intrinsic factor autoantibodies, CgA independently improved prediction of AG (OR 6.5; P = 0.031). An impact of age on CgA positivity and on CgA value was detected (P < 0.0001) while current smoking significantly increased CgA serum levels by 25% (P = 0.0080).

CONCLUSION

CgA qualifies as a novel biomarker for T1D, AP, and AG.

Graves' disease

Graves' disease (GD) is an autoimmune disease that primarily affects the thyroid gland. It is the most common cause of hyperthyroidism and occurs at all ages but especially in women of reproductive age. Graves' hyperthyroidism is caused by autoantibodies to the thyroid-stimulating hormone receptor (TSHR) that act as agonists and induce excessive thyroid hormone secretion, releasing the thyroid gland from pituitary control. TSHR autoantibodies also underlie Graves' orbitopathy (GO) and pretibial myxoedema. Additionally, the pathophysiology of GO (and likely pretibial myxoedema) involves the synergism of insulin-like growth factor 1 receptor (IGF1R) with TSHR autoantibodies, causing retro-orbital tissue expansion and inflammation. Although the aetiology of GD remains unknown, evidence indicates a strong genetic component combined with random potential environmental insults in an immunologically susceptible individual. The treatment of GD has not changed substantially for many years and remains a choice between antithyroid drugs, radioiodine or surgery. However, antithyroid drug use can cause drug-induced embryopathy in pregnancy, radioiodine therapy can exacerbate GO and surgery can result in hypoparathyroidism or laryngeal nerve damage. Therefore, future studies should focus on improved drug management, and a number of important advances are on the horizon.

Remission Rate of Graves' Disease and the Trend of Changes in Serum TSH Receptor Antibodies in Prolonged Antithyroid Drug Treatment

Context: Graves’ disease is an autoimmune disease caused by thyrotropin receptor antibodies (TRAb). These antibodies can be measured and used for the diagnosis, prediction of remission, and risk of Graves’ orbitopathy development. There are three treatments for Graves’ disease that have remained unchanged for the last 75 years: Antithyroid drugs, radioiodine, and surgery. Antithyroid drugs are the first treatment option worldwide and are usually used for 12 - 18 months. Recent reports suggest the use of antithyroid drugs for more than 18 months with better outcomes. This review focuses on two aspects of treatment with antithyroid drugs: The impact of using antithyroid drugs for more than 12 - 18 months on remission rates and the trend of TRAb during prolonged antithyroid drug treatment. Evidence Acquisition: A review was performed in Medline on the published work regarding the duration of ATD treatment and remission of Graves' disease and also ATD treatment and TRAb status during the 1990 - 2019 period. Results: Remission rates are variable (30% - 80%), and many clinical and genetic factors serve as predictors. The long-term use of antithyroid drugs appears to increase remission rates. TRAb values usually decline during ATD treatment, but the trend could occur in two ways: Becoming negative or showing a fluctuating pattern. However, approximately 10% of the patients will remain TRAb-positive after five years of treatment with antithyroid drugs. Conclusions: Antithyroid drugs can be used for long periods with an increase in remission rates, and a gradual decrease in TRAb levels, with the disappearance of TRAb in 90% of the patients after 60 months.

Systemic safety analysis of mycophenolate in Graves' orbitopathy

PURPOSE

The dual antiproliferative mechanism of mycophenolate appears to be beneficial in Graves' orbitopathy (GO).

METHODS

Safety data from the two published mycophenolate trials and the original database of the European Group on Graves' Orbitopathy (EUGOGO) trial were systematically analyzed. Treatment efficacy stratified by individual visual parameters of activity and severity were compared.

RESULTS

A total of 129 adverse events (AE) involving 50 patients (29.4%) were noted among all mycophenolate-treated patients. Mycophenolate sodium plus intravenous glucocorticoid (MPS + GC) group of the EUGOGO trial recorded significantly more AE (55.4% versus 4.6% of patients affected) and serious adverse events (SAE) (12.5% versus 0%) than mycophenolate mofetil (MMF) group of the Chinese trial. None of those SAE was side effect (SE). Most SE in MPS + GC group were mild. Gastrointestinal disorders, infection and liver dysfunction affected 8.8%, 7.1% and 1.2% of all mycophenolate-treated patients (versus 5.4%, 5.4% and 1.2% of all patients on GC monotherapy, respectively). MPS + GC did not significantly increase the risk of infection or liver dysfunction when compared to GC monotherapy. No cytopenia, serious infection or treatment-related mortality was reported. The much higher AE rates of mycophenolate trials in other autoimmune diseases or transplantations suggested that major mycophenolate toxicities were mostly dose- and duration dependent. Mycophenolate, either as monotherapy or as combination, achieved better overall response than GC monotherapy.

CONCLUSION

The risk-benefit ratio of low-dose mycophenolate treatment in active moderate-to-severe GO is highly favorable given its reassuring safety profile with low rate of mild-to-moderate SE and promising efficacy.

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.

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.

New insights into the pathogenesis and nonsurgical management of Graves orbitopathy

Graves orbitopathy, also known as thyroid eye disease or thyroid-associated orbitopathy, is visually disabling, cosmetically disfiguring and has a substantial negative impact on a patient's quality of life. There is increasing awareness of the need for early diagnosis and rapid specialist input from endocrinologists and ophthalmologists. Glucocorticoids are the mainstay of treatment; however, recurrence occurs frequently once these are withdrawn. Furthermore, in >60% of cases, normal orbital anatomy is not restored, and skilled rehabilitative surgery is required. Clinical trials have shown that considerable benefit can be derived from the addition of antiproliferative agents (such as mycophenolate or azathioprine) in preventing deterioration after steroid cessation. In addition, targeted biologic therapies have shown promise, including teprotumumab, which reduces proptosis, rituximab (anti-CD20), which reduces inflammation, and tocilizumab, which potentially benefits both of these parameters. Other strategies such as orbital radiotherapy have had their widespread role in combination therapy called into question. The pathophysiology of Graves orbitopathy has also been revised with identification of new potential therapeutic targets. In this Review we provide an up-to-date overview of the field, outline the optimal management of Graves orbitopathy and summarize the research developments in this area to highlight future research questions and direct future clinical trials.

Reply to Drs. Kiaei and Molinaro Regarding the Publication "Comparison of a Bridge Immunoassay with Two Bioassays for Thyrotropin Receptor Antibody Detection and Differentiation"

Dear Editor,Drs. Kiaei and Molinaro 1 put forth two criticisms of the manuscript published by us 2. They state that the experimental design of this study is flawed and that the authors falsely claim that negative Thyretain™ TSI Reporter BioAssay results for two Graves' diseases patients undergoing drug treatments means the absence of stimulating antibodies. To substantiate this claim Drs. Kiaei and Molinaro point out that the manufacturer of the Thyretain TSI Reporter BioAssay clearly states in the package insert that "[t]he effects of various drug therapies on the performance of this Kit have not been established" 1. Second, the package insert explicitly states that "[a] negative result does not exclude the possibility of the presence of TSI" and results of the test should be interpreted in conjunction with information available from other clinical information, such as physical symptoms and thyroid hormone testing, as recommended by the American Thyroid Association (ATA)". Furthermore they state that the "authors of the manuscript did not consider the manufacturer's warning regarding the intended patient population and the ATA guidelines regarding the interpretation of the test results in conjunction with other clinical information. Instead, the authors based their conclusions on the negative Thyretain TSI Reporter BioAssay results and ignored the patients' clinical history of Graves' 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.

The Potential Link between Gut Microbiota and Serum TRAb in Chinese Patients with Severe and Active Graves' Orbitopathy

BACKGROUND AND OBJECTIVE

A previous study reported alterations in the intestinal microbiota in patients with Graves' orbitopathy (GO). Thyrotropin receptor autoantibody (TRAb) stimulates orbital and periorbital tissues and plays a pivotal role in the development of GO. However, the association between gut microbiota and TRAb in GO patients has still remained elusive. In this study, we explored the relationships between gut microbiota and GO-related traits, in which we applied a metabolic-network-driven analysis to identify GO trait-related modules and extracted significant operational taxonomic units (OTUs).

METHODS

In the present study, we profiled gut microbiota using 16S rRNA gene sequencing in 31 GO patients. We performed metabolic-network-driven analysis to investigate the association between gut microbiota and GO-related traits (e.g., TRAb, TGAb, and TPOAb) in the combination of microbial effects.

RESULTS

Applying microbiome network analysis of cooccurrence patterns and analysis of topological properties, we found that s_Prevotella_copri and f_Prevotellaceae showed a significant correlation with TRAb. In particular, we applied the latent class model to explore the association between gut microbiota and GO-related traits in the combination of microbial effects. It was revealed that the subjects involved in the latent class model with the higher abundance of s_Prevotella_copri and g_Bacteroides had a higher TRAb level.

CONCLUSIONS

Our results revealed the potential relationships between gut microbiota and GO-related traits in the combination of microbial effects. This study may provide a new insight into the interaction between the intestinal microbiota and TRAb-associated immune responses in GO patients.