0000000000262611
AUTHOR
Michael Kanitz
showing 15 related works from this author
OR18-03 Functional TSH Receptor Antibodies Are a Biomarker for Graves’ Disease - a Prospective Trial
2020
Abstract Objective We aimed to evaluate the clinical utility and predictive value of stimulatory (TSAb) and blocking (TBAb) TSH receptor antibodies in the management of Graves’ disease (GD). Methods Hundred well-defined, consecutive, unselected, untreated hyperthyroid patients with GD were enrolled in a prospective two-year trial. Methimazole (MMI) was administered for 24 weeks according to baseline serum concentrations of free T3/free T4. Starting dose was 5–30 mg/day. Through a titration regimen, this dose was respectively tapered or increased at each subsequent study visit as the patient became euthyroid or remained hyperthyroid. Goals of therapy were to maintain normal fT4 and TSH level…
A Novel Long-Term Graves’ Disease Animal Model Confirmed by Functional Thyrotropin Receptor Antibodies
2020
<b><i>Introduction:</i></b> 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. <b><i>Methods:</i></b> BALB/c mice received 7 immunizations with either 10<sup>10</sup> 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 …
Comparison of a Novel Homogeneous Cyclic Amp Assay and a Luciferase Assay for Measuring Stimulating Thyrotropin-Receptor Autoantibodies.
2019
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-dependen…
A cyclic peptide significantly improves thyroid function, thyrotropin-receptor antibodies and orbital mucine /collagen content in a long-term Graves’…
2021
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.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.Thyrotropin binding inhibitory immunoglobulins (TBII, br…
Stimulatory TSH-Receptor Antibodies and Oxidative Stress in Graves Disease
2018
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 …
Clinical relevance of thyroid-stimulating autoantibodies in pediatric graves' disease-a multicenter study.
2014
Context and Objective: The incidence of TSH receptor (TSHR) stimulating autoantibodies (TSAbs) in pediatric Graves' disease (GD) is controversial. This large, multicenter study evaluated the clinical relevance of TSAbs in children with GD both with Graves' orbitopathy (GO) and without orbital disease. Design: We conducted a cross-sectional retrospective study. Setting: Sera were collected in seven American and European academic referral centers and evaluated in a central laboratory. Patients and Samples: A total of 422 serum samples from 157 children with GD, 101 control individuals with other thyroid and nonthyroid autoimmune diseases, and 50 healthy children were studied. Main Outcome Me…
Prevalence and clinical relevance of thyroid stimulating hormone receptor-blocking antibodies in autoimmune thyroid disease
2017
Summary The prevalence and clinical relevance of thyroid stimulating hormone (TSH) receptor (TSHR) blocking antibodies (TBAb) in patients with autoimmune thyroid disease (AITD) was investigated. Serum TBAb were measured with a reporter gene bioassay using Chinese hamster ovary cells. Blocking activity was defined as percentage inhibition of luciferase expression relative to induction with bovine TSH alone (cut-off 40% inhibition). All samples were measured for TSHR stimulatory antibody (TSAb) and TSHR binding inhibiting immunoglobulins (TBII). A total of 1079 unselected, consecutive patients with AITD and 302 healthy controls were included. All unselected controls were negative for TBAb and…
Clinical Relevance of Thyroid-Stimulating Immunoglobulins in Graves' Ophthalmopathy
2011
Purpose Thyroid-stimulating immunoglobulins (TSIs) likely mediate Graves' ophthalmopathy (GO). The clinical relevance of these functional autoantibodies was assessed in GO. Design Cross-sectional trial. Participants A total of 108 untreated patients with GO. Methods Thyroid-stimulating immunoglobulins, assessed with a novel bioassay, bind to the thyrotropin receptor (TSHR) and transmit signals for cyclic adenosine monophosphate (cAMP)-dependent activation of luciferase gene expression. The cAMP/cAMP response element-binding protein/cAMP-regulatory element complex induces luciferase that is quantified after cell lysis. The TSI levels were correlated with activity and severity of GO and compa…
Comparison of a Bridge Immunoassay with Two Bioassays for Thyrotropin Receptor Antibody Detection and Differentiation
2019
AbstractA rapid and fully automated chemiluminescent immunoassay for the detection of thyrotropin receptor autoantibodies (TSHR-Ab) based on a bridge technology was compared with two bioassays that measure either stimulating (TSAb) or blocking (TBAb) antibodies for the detection and differentiation of TSHR-Ab. A total of 229 patients with various thyroid disorders [151 with Graves’ disease (GD), 35 with Hashimoto’s thyroiditis (HT), 32 with nodular goiter, and 11 with thyroid cancer] were included. The bridge immunoassay was performed according to the manufacturer’s instructions (cut-off>0.55 IU/l). TSAb and TBAb were measured with reporter bioassays. Blocking activity was defined as per…
Analytical Performance and Validation of a Bioassay for Thyroid-Blocking Antibodies
2016
A cell-based bioassay for the measurement of thyroid blocking autoantibodies (TBAb) has been recently reported. The analytical performance and validation of this bioassay is assessed and described.Chinese hamster ovary cells expressing a chimeric thyrotropin receptor were treated with bovine (b) TSH and different concentrations of an immunoglobulin G (IgG) monoclonal human TBAb (K1-70). TBAb was measured as a function of luciferase activity relative to bTSH alone and expressed as percent inhibition. Results obtained in the chimeric cell line were compared with those of a wild-type cell line. Analytical performance studies were subsequently performed with the chimeric cell line only.Immunode…
Standardization of a bioassay for thyrotropin receptor stimulating autoantibodies.
2015
Cell-based bioassays for functional thyroid stimulating autoantibodies (TSAb) are sensitive diagnostic tools. However, there is no bioassay available that is standardized with international reference material. We aimed to promote the standardization of the test results among laboratories that perform TSAb bioassays and calibrate TSAb levels against the second international standard (IS) 08/204 from the National Institute for Biological Standards and Control (NIBSC).Serum TSAb activity was measured with a FDA-cleared bioassay that utilizes CHO cells expressing a chimeric thyrotropin receptor (TSHR) and a c-AMP response-element-dependent luciferase. The IS was applied for calibration. TSAb re…
Prospective Trial of Functional Thyrotropin Receptor Antibodies in Graves Disease
2019
Abstract 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 &lt; 140%). Blocking activity was defined as percent inhibition of luciferase expression relative to induction with bovine thyrotropin (TSH, thyroid stimulating hormone) alone (cutoff &gt; 40% inhibitio…
Analytical performance and clinical utility of a bioassay for thyroid-stimulating immunoglobulins.
2013
Abstract The analytical performance and the clinical utility of a thyrotropin receptor (TSHR)–stimulating immunoglobulin (TSI) bioassay were compared with those of a TSHR-binding inhibitory immunoglobulin (TBII) assay. Limits of detection (LoD) and quantitation (LoQ), assay cutoff, and the half-maximal effective concentration (EC50) were measured. Dilution analysis was performed in sera of hyperthyroid patients with Graves disease (GD) during antithyroid treatment (ATD). Titer was defined as the first dilution step at which measurement of TSI or TBII fell below the assay cutoff. The LoD, LoQ, cutoff, and EC50 of the bioassay were 251-, 298-, 814-, and 827-fold lower than for the TBII assay.…
Performance and Specificity of 6 Immunoassays for TSH Receptor Antibodies: A Multicenter Study
2017
Background: The measurement of TSH receptor (TSHR) antibodies is warranted for diagnosis of Graves’ disease (GD). Objective: The performance, detection sensitivity, and specificity of 6 TSHR immunoassays were compared. Methods: Two bioassays and 4 binding assays (Kronus, Immulite, Kryptor, Dynex) were compared in a dilution study performed in patients with autoimmune thyroid disease. Both bioassays were compared to 2 binding assays using stimulatory (M22) and blocking (K1–70) monoclonal antibody (MAb) mixtures. Results: Thirty samples from stimulatory (TSAb)-positive/blocking (TBAb)-negative patients with GD were diluted serially and measured in all assays. Samples were positive until dilut…
Thyroid Stimulating Antibodies Are Highly Prevalent in Hashimoto's Thyroiditis and Associated Orbitopathy
2016
Thyroid-associated orbitopathy (TAO) rarely occurs in patients with Hashimoto's thyroiditis (HT).There is evidence that TSH receptor stimulating antibodies (TSAb) play a role in the pathogenesis of TAO. In this report, the prevalence of TSAb in HT patients with and without TAO was studied.This is a longitudinal observational study.The study took place in an academic joint thyroid-eye clinic.A total of 1055 subjects were included.TSAb was measured with a Food and Drug Administration-cleared bioassay that uses Chinese hamster ovary cells expressing a chimeric TSH receptor and a cAMP response element-dependent luciferase. Results of TSAb activity were reported as percentage of specimen-to-refe…