Development and basic performance verification of a rapid homogeneous bioassay for agonistic antibodies against the thyroid-stimulating hormone receptor.

Graves' disease is a type of autoimmune hyperthyroidism caused by thyroid-stimulating antibodies (TSAb).1 The combination of a porcine thyroid cell bioassay and cyclic adenosine monophosphate (cAMP) immunoassay (TSAb-enzyme immunoassay; EIA) is a clinically approved TSAb measurement method. Due to the requirement of multiple procedures and a long assay time of 6 h in the TSAb-EIA, a simplified and rapid assay is desired. Herein, we developed a rapid homogeneous TSAb bioassay (rapid-TSAb assay) using the human embryonic kidney cell line (HEK293), engineered to express the human thyroid-stimulating hormone receptor (TSHR), along with a cAMP-dependent luminescence biosensor. The measurement consists of three steps: thawing frozen cells, blood sample addition, and luminescence detection. The procedures can be conducted within 1 h. The World Health Organization International Standard TSAb (NIBSC 08/204) stimulated the cells co-expressing TSHR and cAMP biosensor. The intra- and inter-assay coefficients of variance were < 10%. Stimulation activity using wild-type TSHR and chimeric TSHR (Mc4) almost completely correlated with the tested Graves' disease and normal samples. In the rapid-TSAb assay, the evaluation of 39 samples, including TSHR antibody-positive sera, yielded a sensitivity of 100.0% and a specificity of 90.9%, compared to the TSAb-EIA control. The rapid-TSAb assay enables simple and rapid measurement of TSAb and is promising for improving the diagnosis of autoimmune thyroid diseases.

Bioassays for thyrotropin receptor autoantibodies.

Bioassays using animal models were essential tools in the discovery of thyrotropin and in enhancing our understanding of the physiology of the pituitary-thyroid axis. These same bioassays were also instrumental in the discovery of autoantibodies to the thyrotropin receptor (TSH-R-Ab) and in identifying their role in the pathophysiology of Graves' disease. The development of cell-based bioassays led to further advances in our knowledge of the functional activity of TSH-R-Ab and to the discovery that TSH-R-Ab can be either thyroid-stimulating or thyroid blocking, and that they occur in other types of autoimmune thyroid diseases (AITD) besides Graves' disease. More recently, TSH-R-Ab bioassays have been advanced from research tools to clinical laboratory tests. Whereas TSH-R-Ab can be measured with competitive-binding immunoassays, these assays do not provide information on the functional activity of TSH-R-Ab. Bioassays, in contrast, can differentiate between the stimulatory or blocking activity of TSH-R-Ab which provides clinically useful information that can inform the management of patients with AITD. The clinical use of TSH-R-Ab bioassays, however, has been limited to-date by their inherent complexity and long turn-around-time. Recent advances in biosensors have been applied to the development of TSH-R-Ab bioassays that are rapid and simple to perform. We now are entering an era in which bioassays for TSH-R-Ab can be measured routinely by virtually any clinical laboratory.

Outcome of tocilizumab treatment in corticosteroid-resistant thyroid eye disease / Resultados del tratamiento con tocilizumab en la enfermedad ocular tiroidea resistente a glucocorticoides

Introduction: Thyroid eye disease (TED) is a complex and incompletely understood rare autoimmune disorder.ObjectivesTo analyze the experience and the outcomes obtained with the use of intravenous tocilizumab in the treatment of TED.MethodsA retrospective analysis of adult patients diagnosed with active TED resistant to intravenous corticosteroids treated in a tertiary hospital between May 2012 and May 2021.ResultsEleven patients were included with a mean age of 52±12 (range 35–67) years. Nine patients were female and two were male. Patients received a median of 5±3.2 doses. Twenty out of twenty-four eyes achieved inactivation of TED at week 16. Proptosis response was achieved in 6/8 patients and diplopia response in 3/8 patients. The GO-QOL questionnaire showed clinically significant improvement in 9/11 patients. No serious adverse effects were reported during tocilizumab treatment. One patient required decompressive surgery 15 months after tocilizumab therapy.ConclusionThe results obtained show that the use of tocilizumab in the treatment of this pathology can be a good alternative. (AU)

Introducción: La orbitopatía tiroidea (OT) es una enfermedad rara autoinmune compleja que no se conoce completamente.ObjetivosAnalizar la experiencia y los resultados obtenidos con el uso de tocilizumab intravenoso en el tratamiento de la OT.MétodosAnálisis retrospectivo de pacientes adultos diagnosticados de OT activa resistente a glucocorticoides por vía intravenosa tratados en un hospital terciario entre mayo del 2012 y mayo del 2021.ResultadosSe incluyó a 11 pacientes con una edad media de 52±12 (rango 35 a 67) años. Nueve pacientes eran mujeres y 2, hombres. Los pacientes recibieron una mediana de 5±3,2 dosis. Veinte de 24 ojos lograron la inactivación de la OT en la semana 16. Se logró respuesta a la proptosis en 6/8 pacientes y respuesta a diplopía en 3/8 pacientes. El cuestionario GO-QoL mostró una mejora clínicamente significativa en 9/11 pacientes. No se notificaron efectos adversos graves durante el tratamiento con tocilizumab. Un paciente requirió cirugía descompresiva 15 meses después del tratamiento con tocilizumab.ConclusionesLos resultados obtenidos muestran que el uso de tocilizumab en el tratamiento de esta enfermedad puede ser una buena alternativa. (AU)

Outcome of tocilizumab treatment in corticosteroid-resistant thyroid eye disease.

INTRODUCTION: Thyroid eye disease (TED) is a complex and incompletely understood rare autoimmune disorder. OBJECTIVES: To analyze the experience and the outcomes obtained with the use of intravenous tocilizumab in the treatment of TED. METHODS: A retrospective analysis of adult patients diagnosed with active TED resistant to intravenous corticosteroids treated in a tertiary hospital between May 2012 and May 2021. RESULTS: Eleven patients were included with a mean age of 52±12 (range 35-67) years. Nine patients were female and two were male. Patients received a median of 5±3.2 doses. Twenty out of twenty-four eyes achieved inactivation of TED at week 16. Proptosis response was achieved in 6/8 patients and diplopia response in 3/8 patients. The GO-QOL questionnaire showed clinically significant improvement in 9/11 patients. No serious adverse effects were reported during tocilizumab treatment. One patient required decompressive surgery 15 months after tocilizumab therapy. CONCLUSION: The results obtained show that the use of tocilizumab in the treatment of this pathology can be a good alternative.

Brief Report - Monoclonal Antibodies Illustrate the Difficulties in Measuring Blocking TSH Receptor Antibodies.

TSH receptor (TSHR) antibodies are the cause of Graves' disease and may also be found in patients with Hashimoto's thyroiditis. They come in at least three varieties: thyroid stimulating, thyroid blocking and neutral. The measurement of TSH receptor antibodies in Graves' disease and Hashimoto's thyroiditis is a common clinical activity and can be useful in diagnosis and prognosis. We show that it is not possible to detect the blocking variety of TSHR antibody in patients with Graves' disease because the stimulating antibody may overwhelm the measurement of blocking in the bioassays available for their measurement and may blind the valid interpretation of the results. To help explain this in more detail we show a series of studies with monoclonal TSHR antibodies which support this conclusion.

Intestinal microbiota changes in Graves' disease: a prospective clinical study.

Graves' disease (GD) occurs due to an autoimmune dysfunction of thyroid gland cells, leading to manifestations consistent with hyperthyroidism. Various studies have confirmed the link between autoimmune conditions and changes in the composition of intestinal microbial organisms. However, few studies have assessed the relationship between the GD and the changes in intestinal microbiota. Therefore, the present study aimed to investigate changes in intestinal flora that may occur in the setting of GD. Thirty-nine patients with GD and 17 healthy controls were enrolled for fecal sample collection. 16S rRNA sequencing was used to analyze the diversity and composition of the intestinal microbiota. High-throughput sequencing of 16S rRNA genes of intestinal flora was performed on Illumina Hiseq2500 platform. Comparing to healthy individuals, the number of Bacilli, Lactobacillales, Prevotella, Megamonas and Veillonella strains were increased, whereas the number of Ruminococcus, Rikenellaceae and Alistipes strains were decreased among patients with GD. Furthermore, patients with GD showed a decrease in intestinal microbial diversity. Therefore, it indicates that the diversity of microbial strains is significantly reduced in GD patients, and patients with GD will undergo significant changes in intestinal microbiota, by comparing the intestinal flora of GD and healthy controls. These conclusions are expected to provide a preliminary reference for further researches on the interaction mechanism between intestinal flora and GD.

Functional TSH receptor antibodies in children with autoimmune thyroid diseases.

INTRODUCTION: The diagnostic value of the level of TSH receptor antibodies (TSHR-Ab) in the population of children with autoimmune thyroid diseases (AITDs) is still unknown. The aim of this cross-sectional study was to investigate the prevalence of TSHR-Ab in a paediatric cohort with AITD and healthy controls. MATERIALS AND METHODS: A total of 240 serum samples were obtained from 205 patients with AITD, type 1 diabetes (T1D), juvenile arthritis (JA), and healthy controls (C). TSHR stimulating (TSI) and -blocking (TBI) immunoglobulins were measured in cell-based bioassays using CHO cells expressing a chimeric TSHR and a c-AMP response-element-dependent luciferase. TSI was reported as percentage of specimen-to-reference ratio (cutoff 140SRR%). Blocking activity was defined as percent inhibition of luciferase expression relative to induction with bovine TSH alone (40% inhibition). RESULTS: C as well as children with JA and T1D were both TSI and TBI negative. In contrast, children with Graves' disease (GD) were positive for TSI in 47/53 samples (88.7%) while those with thyroidal and orbital GD showed TSI positivity in 95.8% (23/24 samples). Serum TSI levels were SRR% 320 ± 157 and 417 ± 135 in GD and GD + orbitopathy, respectively (p = .02). Children with Hashimoto's thyroiditis (HT) were TSI positive in 4/83 (4.8%) samples, including two with orbital involvement. TSI levels were increased in HT children with vs. those without eye disease (SRR% 177 vs. 51, p < .01). In comparison, TBI were negative in all tested samples of children with GD but positive in one HT sample. CONCLUSIONS: In conclusion, TSI is prevalent in children with GD while the highest serum TSI levels were noted in children with AITD and orbitopathy.

Highly variable sensitivity of five binding and two bio-assays for TSH-receptor antibodies.

PURPOSE: TSH-receptor (TSHR) antibodies (Ab) can be measured with binding or bio-assays. Sensitivity and specificity of five binding and two bio-assays were compared. METHODS: TSHR-blocking (TBAb) and TSHR-stimulating (TSAb) Ab were measured with reporter bio-assays. Blocking activity was defined as percent inhibition of luciferase expression relative to induction with bTSH alone. TSAb was reported as percentage of specimen-to-reference ratio (SRR%). TSHR-binding inhibitory immunoglobulins (TBII) were measured with Kronus, Dynex, Kryptor, Cobas, and Immulite. RESULTS: Sixty patients with Graves' disease (GD), 20 with Hashimoto's thyroiditis (HT), and 20 healthy controls (C) were included. C tested negative in all assays (specificity 100 %) while all 60 hyperthyroid GD patients tested positive in the TSAb bio-assay (sensitivity 100 %). Among these 60 GD patients, 20 had low TSAb positivity (SRR% 140-279), but were TBII positive in only 20 (100 %), 7 (35 %), 9 (45 %), 11 (55 %), and 18 (90 %) using the Kronus, Dynex, Kryptor, Cobas, and Immulite, respectively. In 20 moderate TSAb-positive (SRR% 280-420) patients, TBII tested positive in 20 (100 %), 14 (70 %), 13 (65 %), 16 (80 %), and 19 (95 %), respectively. The high (SRR% > 420) TSAb-positive patients were all TBII positive. All 20 hypothyroid HT patients tested TBAb positive (sensitivity 100 %) in the bio-assay while they tested TBII positive in 20 (100 %), 18 (90 %), 20, 20, and 18, respectively. Results obtained with two luminometers correlated for TSAb positive (r = 0.99, p < 0.001), TBAb positive (r = 0.88, p < 0.001), and C (r = 0.86, p < 0.001). None of the binding assays differentiated between TSAb and TBAb. CONCLUSIONS: Sensitivity is highly variable between binding and bio-assays for TSHR-Abs.

Rapid bioassay for detection of thyroid-stimulating antibodies using cyclic adenosine monophosphate-gated calcium channel and aequorin.

BACKGROUND: Thyroid-stimulating antibodies (TSAb) are known to be responsible for hyperthyroidism in Graves' disease (GD). The conventional methods to measure TSAb depend on cell-based assays that require cumbersome procedures and a sterilized tissue culture technique. The aim of the present study was to develop a ready-to-use cell-based assay for measuring TSAb activity without requiring sterilized conditions. METHODS: We developed a new assay kit using a frozen Chinese hamster ovary cell line expressing the thyroid-stimulating hormone receptor, cyclic adenosine monophosphate (cAMP)-gated calcium channel and aequorin, tentatively named the aequorin TSAb assay. Activated stimulatory G-protein-coupled adenylate cyclase increases intracellular cAMP, which then binds to the cyclic nucleotide-gated calcium channel. Activation of this channel allows Ca(2+) to enter the cell, and the influx of Ca(2+) can be measured with aequorin, which is quantified by a luminometer. Results can be obtained in only 4 h without sterilized conditions. TSAb activities were expressed by international units using the NIBSC 08/204 standard. RESULTS: Positive results of aequorin TSAb were obtained in 197 of 199 (98.9%) of untreated patients with GD. Only 1 of 42 (2.3%) patients with painless thyroiditis had a weakly positive aequorin TSAb. All 45 patients with subacute thyroiditis and 185 normal subjects showed negative aequorin TSAb. As for chronic thyroiditis, all 52 euthyroid patients showed negative aequorin TSAb, but 8 of 50 (16.0%) hypothyroid patients had a positive reaction. However, these positive reactions were not induced by serum thyroid-stimulating hormone (TSH) and were thought to be induced by the stimulating activity of anti-TSH receptor immunoglobulins. Conventional porcine TSAb and Elecsys thyroid-stimulating hormone receptor antibodies were positive in 69.3 and 95.5% of GD, respectively. CONCLUSION: The aequorin TSAb assay was positive in 98.9% of GD and was more sensitive than the conventional assay. This assay can be conducted in only 4 h without sterilized conditions and is practically useful in general clinical laboratories.

In vivo effects of a human thyroid-stimulating monoclonal autoantibody (M22) and a human thyroid-blocking autoantibody (K1-70).

PURPOSE: To study in vivo effects of the human monoclonal TSH receptor (TSHR) autoantibodies M22 (stimulating type) and K1-70 (blocking type) on thyroid hormone levels in rats. METHODS: Serum levels of total T4, free T4, M22 and K1-70 were measured following intramuscular injection of M22 IgG (2-4 µg/animal), K1-70 IgG (10-200 µg/animal) or both into rats. Thyroid pathology was assessed in M22-injected rats. RESULTS: Serum levels of total T4 and free T4 increased in a dose-dependent manner following injection of M22 IgG. Thyroid follicular cell hypertrophy was dependent on the dose of M22 IgG. K1-70 IgG caused a dose dependent decrease of total T4 and free T4 levels in rats receiving K1-70 only. The stimulating effects of M22 IgG on T4 levels in rats were completely inhibited by K1-70 IgG. CONCLUSION: M22 is a potent stimulator of thyroid hormone secretion in vivo. In contrast, K1-70 inhibits thyroid hormone secretion in vivo. Furthermore, K1-70 has the ability to inhibit the stimulating activity of M22 in vivo and as such has potential as a new drug to block TSHR stimulation by autoantibodies in Graves' disease.