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Zouvelou V, Michail M, Belimezi M, Haroniti A, Zisimopoulou P. Characterization of the nicotinic acetylcholine receptor antibodies after an unexpected increase of antibody titer in thymoma associated myasthenia gravis patients. Neuromuscul Disord 2022; 32:847-850. [PMID: 36028368 DOI: 10.1016/j.nmd.2022.08.003] [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: 03/29/2022] [Revised: 07/25/2022] [Accepted: 08/08/2022] [Indexed: 11/16/2022]
Abstract
Two thymoma-associated myasthenia gravis patients with chronic well-controlled disease but an unexpected increase in anti-nAChR autoantibodies titer are reported. The specificity of anti-nAChR autoantibodies directed against extracellular parts of the receptor was studied in order to investigate the discrepancy between clinical and immunological status. Analysis of the anti-nAChR autoantibodies recognizing the extracellular parts of the nAChR revealed that when the concentration of anti-nAChR autoantibodies titer increased both patients had non-anti-α1 autoantibodies. Since the clinical profile of both patients remained unchanged, the increase of non-anti-α1 autoantibodies did not affect the 2 patients' disease progression. Thus, immunotherapy modification due to an increase of anti-nAChR autoantibodies titer could be erroneous and potentially harmful.
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Affiliation(s)
- Vasiliki Zouvelou
- 1st Department of Neurology, Eginition Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Maria Michail
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece; Department of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - Maria Belimezi
- Diagnostic Department, Hellenic Pasteur Institute, Athens, Greece
| | - Anna Haroniti
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece
| | - Paraskevi Zisimopoulou
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece.
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2
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Michail M, Zouvelou V, Belimezi M, Haroniti A, Zouridakis M, Zisimopoulou P. Analysis of nAChR Autoantibodies Against Extracellular Epitopes in MG Patients. Front Neurol 2022; 13:858998. [PMID: 35418927 PMCID: PMC8995881 DOI: 10.3389/fneur.2022.858998] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 02/28/2022] [Indexed: 01/12/2023] Open
Abstract
Myasthenia gravis (MG) is an autoimmune disorder caused by autoantibodies targeting components of the postsynaptic membrane of the neuromuscular junction (NMJ), leading to neuromuscular transmission deficiency. In the vast majority of patients, these autoantibodies target the nicotinic acetylcholine receptor (nAChR), a heteropentameric ion channel anchored to the postsynaptic membrane of the NMJ. Autoantibodies in patients with MG may target all the subunits of the receptor at both their extracellular and intracellular regions. Here, we combine immunoadsorption with a cell-based assay to examine the specificity of the patients' autoantibodies against the extracellular part of the nAChR. Our results reveal that these autoantibodies can be divided into distinct groups, based on their target, with probably different impacts on disease severity. Although our findings are based on a small sample group of patients, they strongly support that additional analysis of the specificity of the autoantibodies of patients with MG could serve as a valuable tool for the clinicians' decision on the treatment strategy to be followed.
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Affiliation(s)
- Maria Michail
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece.,Department of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - Vasiliki Zouvelou
- Department of Neurology, Eginition Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Maria Belimezi
- Diagnostic Department, Hellenic Pasteur Institute, Athens, Greece
| | - Anna Haroniti
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece
| | - Marios Zouridakis
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece
| | - Paraskevi Zisimopoulou
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece
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3
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Autoimmune autonomic ganglionopathy: Ganglionic acetylcholine receptor autoantibodies. Autoimmun Rev 2021; 21:102988. [PMID: 34728435 DOI: 10.1016/j.autrev.2021.102988] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 10/28/2021] [Indexed: 11/24/2022]
Abstract
Autoimmune Autonomic Ganglionopathy (AAG) is a rare immune-mediated disease of the autonomic nervous system. The incidence of AAG is unknown and diagnosis is often difficult due to the multicompartmental nature of the autonomic nervous system - sympathetic, parasympathetic and enteric components - with variable severity and number of components affected. Diagnostic confidence is increased when ganglionic acetylcholine receptor (gnACHR) autoantibodies are detected. Three gnACHR autoantibody diagnostic assays have been described (two binding assays, one receptor immunomodulation assay), but cross-validation between assays is limited. The prevalence of gnACHR autoantibodies in AAG is not known, with application of different clinical and laboratory criteria in the few studies of AAG cohorts and large retrospective laboratory studies of positive gnACHR autoantibodies lacking adequate clinical characterisation. Furthermore, the rate of unexpected gnACHR autoantibody positivity in conditions without overt autonomic dysfunction (false positive results) adds to the complexity of their interpretation. We review the pathophysiology of gnACHR autoantibodies and assays for their detection, with immunomodulation and high titer radioimmunoprecipitation results likely offering better AAG disease identification.
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Zouvelou V, Michail M, Belimezi M, Zisimopoulou P. Subunit specificity of the acetylcholine receptor antibodies in double seropositive myasthenia gravis. Muscle Nerve 2021; 63:E36-E37. [PMID: 33471417 DOI: 10.1002/mus.27177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/10/2021] [Accepted: 01/16/2021] [Indexed: 11/06/2022]
Affiliation(s)
- Vasiliki Zouvelou
- 1st Department of Neurology, Eginition Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Maria Michail
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece
| | - Maria Belimezi
- Diagnostic Department, Hellenic Pasteur Institute, Athens, Greece
| | - Paraskevi Zisimopoulou
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece
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Cetin H, Beeson D, Vincent A, Webster R. The Structure, Function, and Physiology of the Fetal and Adult Acetylcholine Receptor in Muscle. Front Mol Neurosci 2020; 13:581097. [PMID: 33013323 PMCID: PMC7506097 DOI: 10.3389/fnmol.2020.581097] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 08/13/2020] [Indexed: 12/31/2022] Open
Abstract
The neuromuscular junction (NMJ) is a highly developed synapse linking motor neuron activity with muscle contraction. A complex of molecular cascades together with the specialized NMJ architecture ensures that each action potential arriving at the motor nerve terminal is translated into an action potential in the muscle fiber. The muscle-type nicotinic acetylcholine receptor (AChR) is a key molecular component located at the postsynaptic muscle membrane responsible for the generation of the endplate potential (EPP), which usually exceeds the threshold potential necessary to activate voltage-gated sodium channels and triggers a muscle action potential. Two AChR isoforms are found in mammalian muscle. The fetal isoform is present in prenatal stages and is involved in the development of the neuromuscular system whereas the adult isoform prevails thereafter, except after denervation when the fetal form is re-expressed throughout the muscle. This review will summarize the structural and functional differences between the two isoforms and outline congenital and autoimmune myasthenic syndromes that involve the isoform specific AChR subunits.
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Affiliation(s)
- Hakan Cetin
- Department of Neurology, Medical University of Vienna, Vienna, Austria.,Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Richard Webster
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
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Lazaridis K, Baltatzidou V, Tektonidis N, Tzartos SJ. Antigen-specific immunoadsorption of MuSK autoantibodies as a treatment of MuSK-induced experimental autoimmune myasthenia gravis. J Neuroimmunol 2019; 339:577136. [PMID: 31855721 DOI: 10.1016/j.jneuroim.2019.577136] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 12/10/2019] [Accepted: 12/11/2019] [Indexed: 11/16/2022]
Abstract
Myasthenia gravis (MG) is an autoimmune disease affecting the neuromuscular junction. Approximately 9% of MG patients have autoantibodies targeting the muscle specific kinase (MuSK), and are challenging therapeutically, since they often present with more severe symptoms. A useful therapy is plasmapheresis, but it is highly non-specific. Antigen-specific immunoadsorption would only remove the pathogenic autoantibodies, minimizing the possible side effects and maximizing the benefit. We used rats with human MuSK-induced experimental autoimmune MG to perform antigen-specific immunoadsorptions, and found it very effective, resulting in a dramatic autoantibody titer decrease, while immunoadsorbed, but not mock-treated, animals showed an significant improvement of their clinical symptoms. Overall, the procedure was efficient, supporting its application for MG treatment.
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Affiliation(s)
| | | | | | - Socrates J Tzartos
- Hellenic Pasteur Institute, Athens, Greece; Tzartos NeuroDiagnostics, Athens, Greece.
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Lazaridis K, Dalianoudis I, Baltatzidi V, Tzartos SJ. Specific removal of autoantibodies by extracorporeal immunoadsorption ameliorates experimental autoimmune myasthenia gravis. J Neuroimmunol 2017; 312:24-30. [DOI: 10.1016/j.jneuroim.2017.09.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/03/2017] [Accepted: 09/05/2017] [Indexed: 11/29/2022]
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Hu MY, Stathopoulos P, O'connor KC, Pittock SJ, Nowak RJ. Current and future immunotherapy targets in autoimmune neurology. HANDBOOK OF CLINICAL NEUROLOGY 2016; 133:511-36. [PMID: 27112694 DOI: 10.1016/b978-0-444-63432-0.00027-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Randomized controlled treatment trials of autoimmune neurologic disorders are generally lacking and data pertaining to treatment are mostly derived from expert opinion, large case series, and anecdotal reports. The treatment of autoimmune neurologic disorders comprises oncologic therapy (where appropriate) and immunotherapy. In this chapter, we first describe the standard acute and chronic immunotherapies and provide a practical overview of their use in the clinic (mechanisms of action, dosing, monitoring, and side effects). Novel approaches to treatment of autoimmune neurologic disorders, through new drug discovery or repurposing, are dependent on improved mechanistic understanding of immunopathology. Such approaches, with emphasis on monoclonal antibodies, are discussed using the paradigm of three autoimmune neurologic disorders whose immunopathogenesis is better understood, specifically myasthenia gravis, neuromyelitis optica, and chronic inflammatory demyelinating polyradiculoneuropathy. It is important to realize that the treatment strategy and management plan must be individualized for each patient. In general these are influenced by the following: clinical severity, antibody type, presence or absence of cancer, and prior treatment response, if known.
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Affiliation(s)
- Melody Y Hu
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | | | - Kevin C O'connor
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
| | - Sean J Pittock
- Departments of Laboratory Medicine/Pathology and Neurology, Mayo Clinic, College of Medicine, Rochester, MN, USA
| | - Richard J Nowak
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
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Specific adsorbents for myasthenia gravis autoantibodies using mutants of the muscle nicotinic acetylcholine receptor extracellular domains. J Neuroimmunol 2015; 278:19-25. [DOI: 10.1016/j.jneuroim.2014.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 11/27/2014] [Accepted: 12/01/2014] [Indexed: 11/20/2022]
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Kordas G, Lagoumintzis G, Sideris S, Poulas K, Tzartos SJ. Direct proof of the in vivo pathogenic role of the AChR autoantibodies from myasthenia gravis patients. PLoS One 2014; 9:e108327. [PMID: 25259739 PMCID: PMC4178151 DOI: 10.1371/journal.pone.0108327] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 08/20/2014] [Indexed: 11/23/2022] Open
Abstract
Several studies have suggested that the autoantibodies (autoAbs) against muscle acetylcholine receptor (AChR) of myasthenia gravis (MG) patients are the main pathogenic factor in MG; however, this belief has not yet been confirmed with direct observations. Although animals immunized with AChR or injected with anti-AChR monoclonal Abs, or with crude human MG Ig fractions exhibit MG symptoms, the pathogenic role of isolated anti-AChR autoAbs, and, more importantly, the absence of pathogenic factor(s) in the autoAb-depleted MG sera has not yet been shown by in vivo studies. Using recombinant extracellular domains of the human AChR α and β subunits, we have isolated autoAbs from the sera of four MG patients. The ability of these isolated anti-subunit Abs and of the Ab-depleted sera to passively transfer experimental autoimmune MG in Lewis rats was investigated. We found that the isolated anti-subunit Abs were at least as efficient as the corresponding whole sera or whole Ig in causing experimental MG. Abs to both α- and β-subunit were pathogenic although the anti-α-subunit were much more efficient than the anti-β-subunit ones. Interestingly, the autoAb-depleted sera were free of pathogenic activity. The later suggests that the myasthenogenic potency of the studied anti-AChR MG sera is totally due to their anti-AChR autoAbs, and therefore selective elimination of the anti-AChR autoAbs from MG patients may be an efficient therapy for MG.
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Affiliation(s)
- Gregory Kordas
- Department of Pharmacy, University of Patras, Patras, Greece
| | | | | | - Konstantinos Poulas
- Department of Pharmacy, University of Patras, Patras, Greece
- * E-mail: (ST); (KP)
| | - Socrates J. Tzartos
- Department of Pharmacy, University of Patras, Patras, Greece
- Department of Biochemistry, Hellenic Pasteur Institute, Athens, Greece
- * E-mail: (ST); (KP)
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11
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Expression of extracellular domains of muscle specific kinase (MuSK) and use as immunoadsorbents for the development of an antigen-specific therapy. J Neuroimmunol 2014; 276:150-8. [PMID: 25262156 DOI: 10.1016/j.jneuroim.2014.09.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 09/12/2014] [Indexed: 12/17/2022]
Abstract
Antibodies against MuSK seem to be the pathogenic factor in approximately 5-8% of myasthenia gravis (MG) patients. We aim to develop an antigen-specific therapy in which only MuSK antibodies will be removed from patients' plasma using MuSK extracellular domain (MuSK-ECD) as immunoadsorbent. We showed that two different immunoadsorbents, very efficiently and selectively depleted the MuSK antibodies from all tested sera, were stable during the procedure and were reusable. Furthermore, animal experiments showed that the treatment has no toxic effects to the animals. We conclude that the MuSK-ECD-mediated immunoadsorption can be used as an efficient antigen-specific therapy for MuSK-MG.
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12
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Lazaridis K, Zisimopoulou P, Giastas P, Bitzopoulou K, Evangelakou P, Sideri A, Tzartos SJ. Expression of human AChR extracellular domain mutants with improved characteristics. Int J Biol Macromol 2014; 63:210-7. [DOI: 10.1016/j.ijbiomac.2013.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/07/2013] [Accepted: 11/10/2013] [Indexed: 10/26/2022]
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13
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Niarchos A, Zouridakis M, Douris V, Georgostathi A, Kalamida D, Sotiriadis A, Poulas K, Iatrou K, Tzartos SJ. Expression of a highly antigenic and native-like folded extracellular domain of the human α1 subunit of muscle nicotinic acetylcholine receptor, suitable for use in antigen specific therapies for Myasthenia Gravis. PLoS One 2013; 8:e84791. [PMID: 24376846 PMCID: PMC3869910 DOI: 10.1371/journal.pone.0084791] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 11/25/2013] [Indexed: 11/29/2022] Open
Abstract
We describe the expression of the extracellular domain of the human α1 nicotinic acetylcholine receptor (nAChR) in lepidopteran insect cells (i-α1-ECD) and its suitability for use in antigen-specific therapies for Myasthenia Gravis (MG). Compared to the previously expressed protein in P. pastoris (y-α1-ECD), i-α1-ECD had a 2-fold increased expression yield, bound anti-nAChR monoclonal antibodies and autoantibodies from MG patients two to several-fold more efficiently and resulted in a secondary structure closer to that of the crystal structure of mouse α1-ECD. Our results indicate that i-α1-ECD is an improved protein for use in antigen-specific MG therapeutic strategies.
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Affiliation(s)
| | - Marios Zouridakis
- Department of Biochemistry, Hellenic Pasteur Institute, Athens, Greece
| | - Vassilis Douris
- Institute of Biosciences and Applications, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | | | | | | | - Konstantinos Poulas
- Department of Pharmacy, University of Patras, Patras, Greece
- * E-mail: (SJT) (KP)
| | - Kostas Iatrou
- Institute of Biosciences and Applications, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Socrates J. Tzartos
- Department of Pharmacy, University of Patras, Patras, Greece
- Department of Biochemistry, Hellenic Pasteur Institute, Athens, Greece
- * E-mail: (SJT) (KP)
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Lagoumintzis G, Zisimopoulou P, Trakas N, Grapsa E, Poulas K, Tzartos SJ. Scale up and safety parameters of antigen specific immunoadsorption of human anti-acetylcholine receptor antibodies. J Neuroimmunol 2013; 267:1-6. [PMID: 24412396 DOI: 10.1016/j.jneuroim.2013.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 10/25/2013] [Accepted: 11/05/2013] [Indexed: 01/17/2023]
Abstract
Myasthenia gravis is an autoimmune disease usually caused by autoantibodies against the muscle nicotinic acetylcholine receptor (nAChR). Current treatments are not specific, and thus often cause side effects. Here, we elaborate on our previous findings on antigen specific immunoadsorption towards scaling up the method as well as testing whole blood apheresis. The average percent of plasma or whole blood immunoadsorption was up to 79.5%±2.9. Moreover, neither pyrogens were co-administered nor did complement activation occur after immunoadsorption. Thus, antigen-specific apheresis of anti-AChR autoantibodies seems a safe and effective treatment for myasthenia gravis that can be scaled up for clinical testing.
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Affiliation(s)
| | - Paraskevi Zisimopoulou
- Department of Biochemistry, Hellenic Pasteur Institute, 127 Vass. Sofias Avenue, GR 11521, Athens, Greece
| | - Nikolaos Trakas
- Department of Biochemistry, Hellenic Pasteur Institute, 127 Vass. Sofias Avenue, GR 11521, Athens, Greece
| | - Eirini Grapsa
- Department of Nephrology, Aretaieion University Hospital, Athens, Greece
| | | | - Socrates J Tzartos
- Department of Biochemistry, Hellenic Pasteur Institute, 127 Vass. Sofias Avenue, GR 11521, Athens, Greece.
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Zisimopoulou P, Brenner T, Trakas N, Tzartos SJ. Serological diagnostics in myasthenia gravis based on novel assays and recently identified antigens. Autoimmun Rev 2013; 12:924-30. [PMID: 23537507 DOI: 10.1016/j.autrev.2013.03.002] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2013] [Indexed: 10/27/2022]
Abstract
Myasthenia gravis (MG) is the most common immune-mediated disorder of the neuromuscular junction with a prevalence of 200-300/million population and its study has established paradigms for exploring other antibody-mediated diseases. Most MG patients (~85%) have autoantibodies against the muscle acetylcholine receptor (AChR-MG), whereas about 6% of MG patients have autoantibodies against the muscle specific kinase (MuSK-MG). Until recently no autoantibodies could be detected in the remaining patients (seronegative MG). Probably, the most sensitive assays for the detection of the autoantibodies in MG sera have been the radioimmunoprecipitation assays (RIPA) for both types of MG. However, with recent novel methods, not yet used routinely, it has been shown that the "seronegative" MG group includes patients with low levels of autoantibodies or of low affinity, against the known autoantigens, or even with antibodies to recently identified autoantigens. Since MG is heterogeneous in terms of pathophysiology, depending on the autoantigen targeted and on other factors (e.g. presence of thymoma), the serological tests are crucial in verifying the initial clinical diagnosis, whereas frequent measurement of autoantibody levels is important in monitoring the course of the disease and the efficacy of treatment. In addition, in AChR-MG, autoantibodies against the muscle proteins titin and ryanodin receptor have been identified; these antibodies are useful for the classification of MG, indicating the concomitant presence of thymoma, and as prognostic markers.
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Lazaridis K, Zisimopoulou P, Lagoumintzis G, Skriapa L, Trakas N, Evangelakou P, Kanelopoulos I, Grapsa E, Poulas K, Tzartos S. Antigen-specific apheresis of autoantibodies in myasthenia gravis. Ann N Y Acad Sci 2013; 1275:7-12. [PMID: 23278571 DOI: 10.1111/j.1749-6632.2012.06788.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Myasthenia gravis (MG) is an autoimmune disorder affecting the neuromuscular junction, usually caused by autoantibodies against the acetylcholine receptor (AChR) or the muscle-specific kinase (MuSK). Our aim is the development of a therapy based on the selective extracorporeal elimination of anti-AChR or anti-MuSK antibodies. To this end, the extracellular domains of the AChR subunits and MuSK have been expressed in yeast to be used as adsorbents, after optimization, and to obtain large quantities of proteins with near-native structure. We have characterized these proteins with respect to their use as specific immunoadsorbents for MG autoantibodies, and have begun large-scale experiments in order to verify the feasibility of application of the method for therapy. Furthermore, we have initiated animal studies to test possible toxicity and safety issues of the adsorbents or the procedure itself. The successful completion of the scale-up and safety tests will allow the initiation of clinical trials.
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Simon-Keller K, Barth S, Vincent A, Marx A. Targeting the fetal acetylcholine receptor in rhabdomyosarcoma. Expert Opin Ther Targets 2012; 17:127-38. [PMID: 23231343 DOI: 10.1517/14728222.2013.734500] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of childhood and adolescence. Recent efforts to enhance overall survival of patients with clinically advanced RMS have failed and there is a demand for conceptually novel treatments. Immune therapeutic options targeting the fetal nicotinic acetylcholine receptor (fnAChR), which is broadly expressed on RMS, are novel approaches to overcome the therapeutic resistance of RMS. Expression of the fnAChR is restricted to developing fetal muscles, some apparently dispensable ocular muscle fibers and thymic myoid cells. Therefore, after-birth fnAChR is a tumor-associated and almost tumor-specific antigen on RMS cells. AREAS COVERED This review gives an overview on nAChR function and expression pattern in RMS tumor cells, and deals with the immunological significance of fnAChR-expressing cells, including the risk of anti-nAChR autoimmunity as a potential side effect of fnAChR-directed immunotherapies. The article also addresses the advantages and disadvantages of vaccination strategies, immunotoxins and chimeric T cells targeting the fnAChR. EXPERT OPINION Finally, we suggest technical and biological strategies to improve the available immunotherapeutic tools including increasing the in vivo expression of the target fnAChR on RMS cells.
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Affiliation(s)
- Katja Simon-Keller
- University Medical Centre Mannheim, University of Heidelberg, Institute of Pathology, Theodor-Kutzer-Ufer 1-3, D-68135 Mannheim, Germany.
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Díaz-Manera J, Rojas García R, Illa I. Treatment strategies for myasthenia gravis: an update. Expert Opin Pharmacother 2012; 13:1873-83. [DOI: 10.1517/14656566.2012.705831] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Trakas N, Zisimopoulou P, Tzartos SJ. Development of a highly sensitive diagnostic assay for muscle-specific tyrosine kinase (MuSK) autoantibodies in myasthenia gravis. J Neuroimmunol 2011; 240-241:79-86. [DOI: 10.1016/j.jneuroim.2011.09.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 09/16/2011] [Indexed: 10/16/2022]
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Niu L, Guo C, Hao Z, Yuan J, Li Z. Potential roles of recombinant acetylcholine receptor α subunit 1–211 in immunoadsorbent and DNA immunization. J Immunol Methods 2011; 372:14-21. [DOI: 10.1016/j.jim.2011.04.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Accepted: 04/05/2011] [Indexed: 10/17/2022]
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Abstract
Myasthenia gravis is an autoimmune neuromuscular disorder. There are several treatment options, including symptomatic treatment (acetylcholinesterase inhibitors), short-term immunosuppression (corticosteroids), long-term immunosuppression (azathioprine, cyclosporine, cyclophosphamide, methotrexate, mycophenolate mofetil, rituximab, tacrolimus), rapid acting short-term immunomodulation (intravenous immunoglobulin, plasma exchange), and long-term immunomodulation (thymectomy). This review explores in detail these different treatment options. Potential future treatments are also discussed.
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Sun C, Meng F, Li Y, Jin Q, Li H, Li F. Antigen-specific immunoadsorption of anti-acetylcholine receptor antibodies from sera of patients with myastenia gravis. ACTA ACUST UNITED AC 2010; 38:99-102. [PMID: 20196680 DOI: 10.3109/10731191003634778] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND The binding of anti-acetylcholine receptor antibodies (AChRAb) to the main immunogenic region (MIR) of AChR alpha-subunit in the neuromuscular junction is the major pathogenesis of myasthenia gravis (MG). METHODS A synthetic peptide of 10 amino acids corresponding to the MIR of human AChR was coupled with cellulose beads to make an antigen-specific immunoadsorbent (hMIR10-CB). RESULTS The hMIR10-CB could remove AChRAb in MG sera by 40.3+/-2.3%, compared to a tryptophan nonspecific adsorbent Trp-CB by only 22.4+/-1.5% as determined in ELISA, and also showed good blood compatibility for blood cells, plasma ions and plasma proteins as checked in whole blood perfusion in rabbits. CONCLUSIONS The antigen-specific immunoadsorbent hMIR10-CB can serve as a potential candidate in the immunoadsorption treatment of MG.
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Affiliation(s)
- Changyuan Sun
- Department of Immunology and Pathogenic Biology, College of Medicine, Yanbian University, Yanji City, Jilin Province, P. R. China
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Lagoumintzis G, Zisimopoulou P, Kordas G, Lazaridis K, Poulas K, Tzartos SJ. Recent approaches to the development of antigen-specific immunotherapies for myasthenia gravis. Autoimmunity 2010; 43:436-45. [DOI: 10.3109/08916930903518099] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Abstract
Current therapy for myasthenia gravis is directed towards generalized modulation and suppression of the immune system. These approaches have been extensively studied and are effective in many patients with myasthenia, but at the cost of significant adverse effects due to the global effects on the immune system. Future directions in therapy are geared towards focused immunotherapies that aim to improve outcomes while lessening the burden of side effects. This paper reviews both the current accepted treatments for myasthenia gravis as well as promising targeted therapies in development.
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Affiliation(s)
- Hans D Katzberg
- Department of Neurology, Stanford University, Palo Alto, CA, USA
| | - Vera Bril
- University Health Network, University of Toronto, Toronto, Canada
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