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Morshed S, Latif R, Davies TF. Signal responses to neutral TSH receptor antibody - A cycle of damage in the pathophysiology of Graves' disease. J Autoimmun 2023; 136:103012. [PMID: 36898184 DOI: 10.1016/j.jaut.2023.103012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/22/2022] [Accepted: 02/17/2023] [Indexed: 03/11/2023]
Abstract
BACKGROUND Graves' disease is associated with TSH receptor (TSHR) antibodies of variable bioactivity including "neutral" antibodies (N-TSHR-Ab) that bind to the hinge region of the TSHR ectodomain. We have previously found that such antibodies induced thyroid cell apoptosis via excessive mitochondrial and ER stress with elevated reactive oxygen species (ROS). However, the detailed mechanisms by which excess ROS was induced remained unclear. OBJECTIVES To determine how ROS is induced by N-TSHR-monoclonal antibodies (mAb, MC1) mediated signaling and to measure stress in polyorganelles. METHODS Total ROS and mitochondrial ROS was measured by fluorometry of live rat thyrocytes. Live-cell imaging of labelled organelles was carried out using red or green fluorescent dyes. Proteins were detected by Li-Cor Western immunoblots and immunocytochemistry. RESULTS Endocytosis of N-TSHR-mAb induced ROS, disturbed vesicular trafficking, damaged organelles and failed to induce lysosomal degradation and autophagy. We found that the endocytosis triggered signaling cascades involving Gα13 and PKC-δ leading to intrinsic thyroid cell apoptosis. CONCLUSIONS These studies define the mechanism of ROS induction in thyroid cells following the endocytosis of N-TSHR-Ab/TSHR complexes. We suggest that a viscous cycle of stress initiated by cellular ROS and induced by N-TSHR-mAbs may orchestrate overt intra-thyroidal, retro-orbital, and intra-dermal inflammatory autoimmune reactions in patients with Graves' disease.
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Affiliation(s)
- Syed Morshed
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai and the James J, Peters VA Medical Center, New York, NY, USA.
| | - Rauf Latif
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai and the James J, Peters VA Medical Center, New York, NY, USA
| | - Terry F Davies
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai and the James J, Peters VA Medical Center, New York, NY, USA
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Davies TF, Morshed SA, Mezei M, Latif R. Brief Report - Monoclonal Antibodies Illustrate the Difficulties in Measuring Blocking TSH Receptor Antibodies. Front Endocrinol (Lausanne) 2022; 13:943459. [PMID: 35909553 PMCID: PMC9335193 DOI: 10.3389/fendo.2022.943459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 06/23/2022] [Indexed: 11/13/2022] Open
Abstract
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.
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Rescue of thyroid cells from antibody induced cell death via induction of autophagy. J Autoimmun 2021; 126:102746. [PMID: 34801870 DOI: 10.1016/j.jaut.2021.102746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/02/2021] [Accepted: 11/07/2021] [Indexed: 11/20/2022]
Abstract
BACKGROUND Graves' disease (GD) is associated with thyroid stimulating hormone (TSH) receptor (TSHR) antibodies of variable bioactivity. We have previously characterized "neutral" TSHR antibodies (N-TSHR-Abs) that bind to the hinge region of the TSHR ectodomain. We showed that an N-TSHR monoclonal antibody (mAb) failed to induce any G proteins to sustain survival signaling and lead to excessive stress and apoptosis. Furthermore, the addition of TSH, or the antioxidant N-acetyl-l-cysteine (NAC), rescued N-TSHR-mAb-induced apoptotic death. However, the detailed mechanisms of this rescue remained unclear. METHODS Autophagy is activated in response to diverse stress related stimuli so we have, therefore, studied the autophagy response in rat thyroid cells (FRTL-5) during N-TSHR-mAb induced thyrocyte stress and apoptosis using the In Cell Western technique for quantitation along with immunocytochemistry. RESULTS Under starvation conditions with N-TSHR-mAb the addition of TSH or NAC prevented thyroid cell death by enhancing autophagy. This was evidenced by elevated levels of autophagy related proteins including beclin 1, LC3A, LC3B, ULK1, p62, and also activated pink and perkin mitophagy related proteins. The phenomenon was further confirmed by image analyses using Cyto-ID and Mito-ID autophagy detection systems. We also found that either TSH or NAC enhanced PKA, Akt, mTORC, AMPK, Sirtuins, PGC1α, NRF-2, mitofusin-2, TFAM and catalase in the N-TSHR-mAb stressed cells. Thus TSH or NAC restored cell survival signaling which reduced cell stress and enhanced mitochondrial biogenesis. The N-TSHR-mAb also activated cytochrome-C, Bax, caspase-9, caspase-3A, and had less effect on FADD or caspase-8 indicating activation of the intrinsic pathway for apoptosis. CONCLUSIONS These findings indicated that TSH or antioxidant can rescue thyroid cells from N-TSHR-mAb induced apoptosis via enhanced autophagy. These observations signify that N-TSHR-mAb in GD under low TSH conditions caused by the hyperthyroidism could be detrimental for thyrocyte survival which would be another factor able to precipitate ongoing autoinflammation.
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Morshed SA, Ma R, Latif R, Davies TF. Biased signaling by thyroid-stimulating hormone receptor-specific antibodies determines thyrocyte survival in autoimmunity. Sci Signal 2018; 11:11/514/eaah4120. [PMID: 29363585 DOI: 10.1126/scisignal.aah4120] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The thyroid-stimulating hormone receptor (TSHR) is a heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptor (GPCR). Autoimmune hyperthyroidism, commonly known as Graves' disease (GD), is caused by stimulating autoantibodies to the TSHR. We previously described TSHR-specific antibodies (TSHR-Abs) in GD that recognize linear epitopes in the cleavage region of the TSHR ectodomain (C-TSHR-Abs) and induce thyroid cell apoptosis instead of stimulating the TSHR. We found that C-TSHR-Abs entered the cell through clathrin-mediated endocytosis but did not trigger endosomal maturation and failed to undergo normal vesicular sorting and trafficking. We found that stimulating TSHR-Abs (S-TSHR-Abs) activated Gαs and, to a lesser extent, Gαq but that C-TSHR-Abs failed to activate any of the G proteins normally activated in response to TSH. Furthermore, specific inhibition of G proteins in the presence of S-TSHR-mAbs or TSH resulted in a similar failure of endosomal maturation as that caused by C-TSHR-mAbs. Hence, whereas S-TSHR-mAbs and TSH contributed to normal vesicular trafficking of TSHR through the activation of major G proteins, the C-TSHR-Abs resulted in GRK2- and β-arrestin-1-dependent biased signaling, which is interpreted as a danger signal by the cell. Our observations suggest that the binding of antibodies to different TSHR epitopes may decrease cell survival. Antibody-induced cell injury and the response to cell death amplify the loss of self-tolerance, which most likely helps to perpetuate GPCR-mediated autoimmunity.
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Affiliation(s)
- Syed A Morshed
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai and the James J. Peters VA Medical Center, New York, NY 10029, USA.
| | - Risheng Ma
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai and the James J. Peters VA Medical Center, New York, NY 10029, USA
| | - Rauf Latif
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai and the James J. Peters VA Medical Center, New York, NY 10029, USA
| | - Terry F Davies
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai and the James J. Peters VA Medical Center, New York, NY 10029, USA
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Giuliani C, Saji M, Bucci I, Napolitano G. Bioassays for TSH Receptor Autoantibodies, from FRTL-5 Cells to TSH Receptor-LH/CG Receptor Chimeras: The Contribution of Leonard D. Kohn. Front Endocrinol (Lausanne) 2016; 7:103. [PMID: 27504107 PMCID: PMC4958915 DOI: 10.3389/fendo.2016.00103] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 07/12/2016] [Indexed: 12/16/2022] Open
Abstract
Since the discovery 60 years ago of the "long-acting thyroid stimulator" by Adams and Purves, great progress has been made in the detection of thyroid-stimulating hormone (TSH) receptor (TSHR) autoantibodies (TRAbs) in Graves' disease. Today, commercial assays are available that can detect TRAbs with high accuracy and provide diagnostic and prognostic evaluation of patients with Graves' disease. The present review focuses on the development of TRAbs bioassays, and particularly on the role that Leonard D. Kohn had in this. Indeed, 30 years ago, the Kohn group developed a bioassay based on the use of FRTL-5 cells that was characterized by high reproducibility, feasibility, and diagnostic accuracy. Using this FRTL-5 bioassay, Kohn and his colleagues were the first to develop monoclonal antibodies (moAbs) against the TSHR. Furthermore, they demonstrated the multifaceted functional nature of TRAbs in patients with Graves' disease, with the identification of stimulating and blocking TRAbs, and even antibodies that activated pathways other than cAMP. After the cloning of the TSHR, the Kohn laboratory constructed human TSHR-rat luteinizing hormone/chorionic gonadotropin receptor chimeras. This paved the way to a new bioassay based on the use of non-thyroid cells transfected with the Mc4 chimera. The new Mc4 bioassay is characterized by high diagnostic and prognostic accuracy, greater than for other assays. The availability of a commercial kit based on the Mc4 chimera is spreading the use of this assay worldwide, indicating its benefits for these patients with Graves' disease. This review also describes the main contributions made by other researchers in TSHR molecular biology and TRAbs assay, especially with the development of highly potent moAbs. A comparison of the diagnostic accuracies of the main TRAbs assays, as both immunoassays and bioassays, is also provided.
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Affiliation(s)
- Cesidio Giuliani
- Unit of Endocrinology, Department of Medicine and Sciences of Aging, Ce.S.I.-Me.T., University of Chieti–Pescara, Chieti, Italy
- *Correspondence: Cesidio Giuliani,
| | - Motoyasu Saji
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, The Ohio State University, Columbus, OH, USA
| | - Ines Bucci
- Unit of Endocrinology, Department of Medicine and Sciences of Aging, Ce.S.I.-Me.T., University of Chieti–Pescara, Chieti, Italy
| | - Giorgio Napolitano
- Unit of Endocrinology, Department of Medicine and Sciences of Aging, Ce.S.I.-Me.T., University of Chieti–Pescara, Chieti, Italy
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Morshed SA, Davies TF. Graves' Disease Mechanisms: The Role of Stimulating, Blocking, and Cleavage Region TSH Receptor Antibodies. Horm Metab Res 2015; 47:727-34. [PMID: 26361259 PMCID: PMC5047290 DOI: 10.1055/s-0035-1559633] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The immunologic processes involved in Graves' disease (GD) have one unique characteristic--the autoantibodies to the TSH receptor (TSHR)--which have both linear and conformational epitopes. Three types of TSHR antibodies (stimulating, blocking, and cleavage) with different functional capabilities have been described in GD patients, which induce different signaling effects varying from thyroid cell proliferation to thyroid cell death. The establishment of animal models of GD by TSHR antibody transfer or by immunization with TSHR antigen has confirmed its pathogenic role and, therefore, GD is the result of a breakdown in TSHR tolerance. Here we review some of the characteristics of TSHR antibodies with a special emphasis on new developments in our understanding of what were previously called "neutral" antibodies and which we now characterize as autoantibodies to the "cleavage" region of the TSHR ectodomain.
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Affiliation(s)
- S A Morshed
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai, James J. Peters VA Medical Center, New York, USA
| | - T F Davies
- Thyroid Research Unit, Icahn School of Medicine at Mount Sinai, James J. Peters VA Medical Center, New York, USA
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Oh SR, Priel A, Granet DB, Levi L, Korn BS, Kikkawa DO. Thyroid-related orbitopathy: a multidisciplinary perspective. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/eop.10.81] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Meroni PL, Biggioggero M, Pierangeli SS, Sheldon J, Zegers I, Borghi MO. Standardization of autoantibody testing: a paradigm for serology in rheumatic diseases. Nat Rev Rheumatol 2013; 10:35-43. [PMID: 24275965 DOI: 10.1038/nrrheum.2013.180] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Autoantibody measurement is an excellent tool to confirm the diagnosis of rheumatic autoimmune diseases. Hence, reliability and harmonization of autoantibody testing are essential, but these issues are still a matter of debate. Intrinsic variability in analytes and reagents as well as heterogeneity of the techniques are the main reasons for discrepancies in inter-laboratory variations and reporting of test results. This lack of reliability might be responsible for wrong or missed diagnoses, as well as additional costs due to assay repetition, unnecessary use of confirmatory tests and/or consequent diagnostic investigations. To overcome such issues, the standardization of autoantibody testing requires efforts on all aspects of the assays, including the definition of the analyte, the pre-analytical stages, the calibration method and the reporting of results. As part of such efforts, the availability of suitable reference materials for calibration and quality control would enable the development of a reliable reference system. Strong-positive sera from patients have been used as reference materials in most of the autoantibody assays for rheumatic diseases; however, antigen-affinity-purified immunoglobulin fractions or in some cases reliable monoclonal antibody preparations offer more adequate tools for standardization. Systematic assessments of reference materials are currently underway, and preliminary results appear to be encouraging.
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Affiliation(s)
- Pier Luigi Meroni
- Department of Clinical Sciences and Community Health, Division of Rheumatology, Istituto G. Pini, University of Milan, Piazza C. Ferrari 1, 20122 Milan, Italy
| | - Martina Biggioggero
- Department of Clinical Sciences and Community Health, Division of Rheumatology, Istituto G. Pini, University of Milan, Piazza C. Ferrari 1, 20122 Milan, Italy
| | - Silvia S Pierangeli
- Divisions of Rheumatology and Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555-0883, USA
| | - Joanna Sheldon
- Protein Reference Unit, St George's Hospital, Blackshaw Road, London SW17 0NH, UK
| | - Ingrid Zegers
- European Commission Joint Research Centre, Institute for Reference Materials and Measurements (IRMM), Retieseweg 111, B-2440 Geel, Belgium
| | - Maria Orietta Borghi
- Istituto Auxologico Italiano, Experimental Laboratory of Immune-Rheumatology, Via G. Zucchi 18, 20095 Cusano Milanino, Milan, Italy
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Gleicher N, Weghofer A, Kushnir VA, Shohat-Tal A, Lazzaroni E, Lee HJ, Barad DH. Is androgen production in association with immune system activation potential evidence for existence of a functional adrenal/ovarian autoimmune system in women? Reprod Biol Endocrinol 2013; 11:58. [PMID: 23805952 PMCID: PMC3700837 DOI: 10.1186/1477-7827-11-58] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 06/24/2013] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Low functional ovarian reserve (FOR) is at all ages associated with low testosterone (T) levels. Causes are, however, unknown. We, therefore, investigate whether androgens with low FOR are associated with non-specific immune system activation. METHODS 322 infertile women with low and normal FOR (controls) were assessed with a broadly based immune profile, which in previous studies has proven effective in differentiating infertile patients with and without immune system activation. Patients were either immune-positive (greater than or equal to one positive tested parameter) or immune negative (no positive test). 135 suffered from prematurely diminished FOR (POA/OPOI; < age 38), 155 from physiologic diminished FOR due to age (DOR; > age 40), and 32 were controls (< age 38 with normal age-specific FOR). Prevalence of immune-positive vs. negative was assessed in all 3 patient groups. RESULTS Women with immune abnormalities, overall, demonstrated higher total T (TT, P = 0.004) and free T (FT, P < 0.001) levels than those without. The three clinical and two immunologic-defined patient groups demonstrated significant statistical interaction in mean TT (P = 0.008), with mean TT and FT in women with positive immune findings being significantly higher in control than in POA/OPOI and physiologic DOR patients (all 4 differences P < 0.001). No such differences between the three groups were seen in women without immune abnormalities. CONCLUSIONS In this study we used a definition of immune-positivity, which favors sensitivity over specificity, resulting in significant numbers of false-positives but likely only few false-negatives. The study allows suggesting the possibility of an immune system-derived androgen-production factor (APF), which maintains normal androgen levels but is deficient in women with low FOR and immune system inactivity. Existence of such an APF would suggest the presence of a still unknown functional adrenal autoimmune system.
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Affiliation(s)
- Norbert Gleicher
- Center for Human Reproduction, New York, NY 10021, USA
- Foundation for Reproductive Medicine, New York, NY 10021, USA
| | - Andrea Weghofer
- Center for Human Reproduction, New York, NY 10021, USA
- Department of Gynecologic Endocrinology and Reproductive Medicine, Medical University Vienna, Vienna 1090, Austria
| | | | | | | | - Ho-Joon Lee
- Center for Human Reproduction, New York, NY 10021, USA
| | - David H Barad
- Center for Human Reproduction, New York, NY 10021, USA
- Foundation for Reproductive Medicine, New York, NY 10021, USA
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Morshed SA, Latif R, Davies TF. Delineating the autoimmune mechanisms in Graves' disease. Immunol Res 2013; 54:191-203. [PMID: 22434518 DOI: 10.1007/s12026-012-8312-8] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The immunologic processes involved in autoimmune thyroid disease (AITD), particularly Graves' disease (GD), are similar to other autoimmune diseases with the emphasis on the antibodies as the most unique aspect. These characteristics include a lymphocytic infiltrate at the target organs, the presence of antigen-reactive T and B cells and antibodies, and the establishment of animal models of GD by antibody transfer or immunization with antigen. Similar to other autoimmune diseases, risk factors for GD include the presence of multiple susceptibility genes, including certain HLA alleles, and the TSHR gene itself. In addition, a variety of known risk factors and precipitators have been characterized including the influence of sex and sex hormones, pregnancy, stress, infection, iodine and other potential environmental factors. The pathogenesis of GD is likely the result of a breakdown in the tolerance mechanisms, both at central and peripheral levels. Different subsets of T and B cells together with their regulatory populations play important roles in the propagation and maintenance of the disease process. Understanding different mechanistic in the complex system biology interplay will help to identify unique factors contributing to the AITD pathogenesis.
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Affiliation(s)
- Syed A Morshed
- Thyroid Research Unit, Mount Sinai School of Medicine, James J. Peters VA Medical Center, 130 West Kingsbridge Rd, Bronx, New York, NY 10468, USA.
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Autoantibodies to intracellular antigens: Generation and pathogenetic role. Autoimmun Rev 2011; 10:503-8. [DOI: 10.1016/j.autrev.2011.03.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 03/06/2011] [Indexed: 12/21/2022]
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Abstract
Targeted nanoparticles have the potential to improve drug delivery efficiencies by more than two orders of magnitude, from the ~ 0.1% which is common today. Most pharmacologically agents on the market today are small drug molecules, which diffuse across the body’s blood-tissue barriers and distribute not only into the lesion, but into almost all organs. Drug actions in the non-lesion organs are an inescapable part of the drug delivery principle, causing “side-effects” which limit the maximally tolerable doses and result in inadequate therapy of many lesions. Nanoparticles only cross barriers by design, so side-effects are not built into their mode of operation. Delivery rates of almost 90% have been reported. This review examines the significance of these statements and checks how far they need qualification. What type of targeting is required? Is a single targeting sufficient? What new types of clinical challenge, such as immunogenicity, might attend the use of targeted nanoparticles?
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Haas AK, Kleinau G, Hoyer I, Neumann S, Furkert J, Rutz C, Schülein R, Gershengorn MC, Krause G. Mutations that silence constitutive signaling activity in the allosteric ligand-binding site of the thyrotropin receptor. Cell Mol Life Sci 2010; 68:159-67. [PMID: 20652618 DOI: 10.1007/s00018-010-0451-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 06/08/2010] [Accepted: 06/30/2010] [Indexed: 11/29/2022]
Abstract
The thyrotropin receptor (TSHR) exhibits elevated cAMP signaling in the basal state and becomes fully activated by thyrotropin. Previously we presented evidence that small-molecule ligands act allosterically within the transmembrane region in contrast to the orthosteric extracellular hormone-binding sites. Our goal in this study was to identify positions that surround the allosteric pocket and that are sensitive for inactivation of TSHR. Homology modeling combined with site-directed mutagenesis and functional characterization revealed seven mutants located in the allosteric binding site that led to a decrease of basal cAMP signaling activity. The majority of these silencing mutations, which constrain the TSHR in an inactive conformation, are found in two clusters when mapped onto the 3D structural model. We suggest that the amino acid positions identified herein are indicating locations where small-molecule antagonists, both neutral antagonists and inverse agonists, might interfere with active TSHR conformations.
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Affiliation(s)
- Ann-Karin Haas
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Str.10, 13125, Berlin, Germany.
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14
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van Zeijl CJJ, Fliers E, van Koppen CJ, Surovtseva OV, de Gooyer ME, Mourits MP, Wiersinga WM, Miltenburg AMM, Boelen A. Effects of thyrotropin and thyrotropin-receptor-stimulating Graves' disease immunoglobulin G on cyclic adenosine monophosphate and hyaluronan production in nondifferentiated orbital fibroblasts of Graves' ophthalmopathy patients. Thyroid 2010; 20:535-44. [PMID: 20384487 DOI: 10.1089/thy.2009.0447] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Orbital fibroblasts are involved in the pathogenesis of Graves' ophthalmopathy (GO) by producing hyaluronan (HA), synthesized by three types of hyaluronan synthases (HAS1, HAS2, and HAS3). Thyrotropin receptors (TSHR) expressed in orbital fibroblasts activate the cyclic adenosine monophosphate (cAMP) pathway. Only sparse data are available at present supporting a role for TSHR activation in the regulation of HA in GO orbital fibroblasts. We hypothesize that TSHR activation, via cAMP signaling, results in induction of HAS1-3 mRNA expression and HA production by nondifferentiated GO orbital fibroblasts. METHODS Cultured nondifferentiated orbital fibroblasts obtained during orbital decompression surgery from 15 GO patients were stimulated with recombinant human TSH (rhTSH), TSHR-stimulating Graves' disease immunoglobulin G (GD-IgG) or forskolin (FSK), or interleukin-1beta (IL-1beta). RESULTS FSK significantly stimulated cAMP production, HAS1 and HAS3 mRNA expression, and HA secretion in orbital fibroblasts. IL-1beta slightly induced cAMP production, but induced HAS mRNA expression of all three isoforms and HA secretion. In contrast, the effects of rhTSH and GD-IgG on cAMP were modest and absent, respectively, and on HAS mRNA and HA synthesis were completely absent. CONCLUSIONS The strong increase in cAMP synthesis by FSK in nondifferentiated GO orbital fibroblasts results in increased HA synthesis, but TSHR activation by rhTSH or GD-IgG does not result in altered HA synthesis. Our results do not support a predominant role for GD-IgGs in the accumulation of orbital glycosaminoglycans; cytokines like IL-1beta seem largely responsible for excessive glycosaminoglycan production by nondifferentiated orbital fibroblasts in early immunopathogenesis of GO.
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Affiliation(s)
- Clementine J J van Zeijl
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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Latif R, Morshed SA, Zaidi M, Davies TF. The thyroid-stimulating hormone receptor: impact of thyroid-stimulating hormone and thyroid-stimulating hormone receptor antibodies on multimerization, cleavage, and signaling. Endocrinol Metab Clin North Am 2009; 38:319-41, viii. [PMID: 19328414 DOI: 10.1016/j.ecl.2009.01.006] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The thyroid-stimulating hormone receptor (TSHR) has a central role in thyrocyte function and is also one of the major autoantigens for the autoimmune thyroid diseases. We review the post-translational processing, multimerization, and intramolecular cleavage of TSHR, all of which may modulate its signal transduction. The recent characterization of monoclonal antibodies to the TSHR, including stimulating, blocking, and neutral antibodies, have also revealed unique biologic insights into receptor activation and the variety of these TSHR antibodies may help explain the multiple clinical phenotypes seen in autoimmune thyroid diseases. Knowledge of the structure/function relationship of the TSHR is beginning to provide a greater understanding of thyroid physiology and thyroid autoimmunity.
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Affiliation(s)
- Rauf Latif
- Thyroid Research Unit, Mount Sinai School of Medicine and the James J. Peters VA Medical Center, New York, NY 10468, USA.
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Kleinau G, Krause G. Thyrotropin and homologous glycoprotein hormone receptors: structural and functional aspects of extracellular signaling mechanisms. Endocr Rev 2009; 30:133-51. [PMID: 19176466 DOI: 10.1210/er.2008-0044] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The TSH receptor (TSHR) together with the homologous lutropin/choriogonadotropin receptor and the follitropin receptor are glycoprotein hormone receptors (GPHRs). They constitute a subfamily of the rhodopsin-like G protein-coupled receptors with seven transmembrane helices. GPHRs and their corresponding hormones are pivotal proteins with respect to a variety of physiological functions. The identification and characterization of intra- and intermolecular signaling determinants as well as signaling mechanisms are prerequisites to gaining molecular insights into functions and (pathogenic) dysfunctions of GPHRs. Knowledge about activation mechanisms is fragmentary, and the specific aspects have still not been understood in their entirety. Therefore, here we critically review the data available for these receptors and bring together structural and functional findings with a focus on the important large extracellular portion of the TSHR. One main focus is the particular function of structural determinants in the initial steps of the activation such as: 1) hormone binding at the extracellular site; 2) hormone interaction at a second binding site in the hinge region; 3) signal regulation via sequence motifs in the hinge region; and 4) synergistic signal amplification by cooperative effects of the extracellular loops toward the transmembrane region. Comparison and consolidation of data from the homologous glycoprotein hormone receptors TSHR, follitropin receptor, and lutropin/choriogonadotropin receptor provide an overview of extracellular mechanisms of signal initiation, conduction, and regulation at the TSHR and homologous receptors. Finally, we address the issue of structural implications and suggest a refined scenario for the initial signaling process on GPHRs.
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Affiliation(s)
- Gunnar Kleinau
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
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Gleicher N, Barad D, Weghofer A. Functional autoantibodies, a new paradigm in autoimmunity? Autoimmun Rev 2007; 7:42-45. [DOI: 10.1016/j.autrev.2007.06.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2007] [Revised: 06/15/2007] [Accepted: 06/15/2007] [Indexed: 10/23/2022]
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18
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Hoyo-Becerra C, López-Avalos MD, Pérez J, Miranda E, Rojas-Ríos P, Fernández-Llebrez P, Grondona JM. Continuous delivery of a monoclonal antibody against Reissner's fiber into CSF reveals CSF-soluble material immunorelated to the subcommissural organ in early chick embryos. Cell Tissue Res 2006; 326:771-86. [PMID: 16788834 DOI: 10.1007/s00441-006-0231-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Accepted: 04/24/2006] [Indexed: 10/24/2022]
Abstract
The subcommissural organ (SCO) is an ependymal differentiation located in the dorsal midline of the caudal diencephalon under the posterior commissure. SCO cells synthesize and release glycoproteins into the cerebrospinal fluid (CSF) forming a threadlike structure known as Reissner's fiber (RF), which runs caudally along the ventricular cavities and the central canal of the spinal cord. Numerous monoclonal antibodies have been raised against bovine RF and the secretory material of the SCO. For this study, we selected the 4F7 monoclonal antibody based on its cross-reactivity with chick embryo SCO glycoproteins in vivo. E4 chick embryos were injected with 4F7 hybridoma cells or with the purified monoclonal antibody into the ventricular cavity of the optic tectum. The hybridoma cells survived, synthesized and released antibody into the CSF for at least 13 days after the injection. E5 embryos injected with 4F7 antibody displayed precipitates in the CSF comprising both the monoclonal antibody and anti-RF-positive material. Such aggregates were never observed in control embryos injected with other monoclonal antibodies used as controls. Western blot analysis of CSF from E4-E6 embryos revealed several immunoreactive bands to anti-RF (AFRU) antibody. We also found AFRU-positive material bound to the apical surface of the choroid plexus primordia in E5 embryos. These and other ultrastructural evidence suggest the existence of soluble SCO-related molecules in the CSF of early chick embryos.
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Affiliation(s)
- C Hoyo-Becerra
- Departamento de Biología Celular, Genética y Fisiología, Campus de Teatinos, Universidad de Málaga, Málaga, Spain
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