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Tavasoli A. Immune mediated myasthenia gravis in children, current concepts and new treatments: A narrative review article. IRANIAN JOURNAL OF CHILD NEUROLOGY 2024; 18:21-42. [PMID: 38988843 PMCID: PMC11231678 DOI: 10.22037/ijcn.v18i3.45054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/14/2024] [Accepted: 05/19/2024] [Indexed: 07/12/2024]
Abstract
Myasthenia gravis (MG) is the most frequent transmission disease in the neuromuscular junction. Juvenile myasthenia gravis (JMG) is an autoimmune antibody-mediated disease of postsynaptic endplate defined as MG presentation in patients before the age of 18 years old. While many clinical features of JMG are identical to the adults, there are some significant differences between them regarding presentation, clinical course, antibody level, and thymus histopathology. In JMG, ocular symptoms are more frequent, the clinical course is comparably benign, and the outcome is better than adult MG. Antibodies attack the muscle endplate proteins in the postsynaptic membrane and interfere with transmission. These antibodies in most patients are against the acetylcholine receptors, but they may also be directed toward muscle-specific kinase, lipoprotein-related protein 4, and agrin. Findings show racial influences and genetic effects on the occurrence of JMG. The essential clinical symptom is fatigable weakness of muscles that can be in the form of isolated ocular type or more disseminated weakness. The diagnosis of JMG is essentially clinical, with fluctuating patterns of weakness and easy fatigability, but a series of diagnostic evaluations can confirm the diagnosis. Precise diagnostic evaluation and distinction from congenital myasthenic syndromes is critical. The treatment plan is conducted according to the clinical course (ocular or generalized), antibody type, and disease severity. The mainstay of treatment includes symptomatic therapy, long-lasting immunosuppressive treatment and treatment of myasthenic crisis. Novel medications are introduced and conducted to the specific pathophysiologic mechanisms of the disease, and they are used primarily in the refractory MG.
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Affiliation(s)
- Azita Tavasoli
- Department of Pediatric Neurology , Iran University of Medical Sciences, Tehran, Iran
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Ricciardi R, Latini E, Guida M, Koneczny I, Lucchi M, Maestri M, De Rosa A, Vincent A. Acetylcholinesterase inhibitors are ineffective in MuSK-antibody positive myasthenia gravis: Results of a study on 202 patients. J Neurol Sci 2024; 461:123047. [PMID: 38759248 DOI: 10.1016/j.jns.2024.123047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 05/04/2024] [Accepted: 05/10/2024] [Indexed: 05/19/2024]
Abstract
BACKGROUND Myasthenia gravis (MG) with MuSK antibodies (MuSK-MG) represents a distinct subtype with different responses to treatments compared to patients with AChR antibodies, especially in terms of tolerance to acetylcholinesterase inhibitors (AChEI). However, AChEI are often used as first line symptomatic treatment in MuSK-MG, despite reports that they are poorly tolerated, seldom effective or even deleterious. METHODS We analyzed demographic, clinical and therapeutic responses and side-effects in the large cohort of 202 MuSK-MG patients cared for at the MG Clinic of Azienda Ospedaliero-Universitaria Pisana. RESULTS 165 patients had received AChEI at first evaluation. Only 7/165 patients (4.2%) reported an initial clinical benefit. Conversely, 76.9% of patients reported at least one side effect, most commonly neuromuscular hyperexcitability (68.4%), gastrointestinal (53.9%) and neurovegetative (35.8%) disturbances. 56 (33.9%) patients reported a concomitant worsening of muscle weakness and twelve patients (7.3%) suffered a cholinergic crisis. According to these patients, the severity of cholinergic side effects was greater at higher doses of AChEI, but side effects occurred regardless of the dose administered and ceased once the drug was discontinued. CONCLUSIONS This is the largest population of MuSK-MG patients reported for perceived responsiveness and tolerance to AChEI treatment. Our obervations strongly suggest avoiding this treatment in MuSK-MG.
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Affiliation(s)
- R Ricciardi
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Italy; CardioThoracic and Vascular Surgery Department, University of Pisa, Italy
| | - E Latini
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Italy.
| | - M Guida
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Italy
| | - I Koneczny
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, 1090 Vienna, Austria
| | - M Lucchi
- CardioThoracic and Vascular Surgery Department, University of Pisa, Italy
| | - M Maestri
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Italy
| | - A De Rosa
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Italy
| | - A Vincent
- Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
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Ma C, Liu D, Wang B, Yang Y, Zhu R. Advancements and prospects of novel biologicals for myasthenia gravis: toward personalized treatment based on autoantibody specificities. Front Pharmacol 2024; 15:1370411. [PMID: 38881870 PMCID: PMC11177092 DOI: 10.3389/fphar.2024.1370411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 05/06/2024] [Indexed: 06/18/2024] Open
Abstract
Myasthenia gravis (MG) is an antibody-mediated autoimmune disease with a prevalence of 150-250 cases per million individuals. Autoantibodies include long-lived antibodies against the acetylcholine receptor (AChR), mainly of the IgG1 subclass, and IgG4, produced almost exclusively by short-lived plasmablasts, which are prevalent in muscle-specific tyrosine kinase (MuSK) myasthenia gravis. Numerous investigations have demonstrated that MG patients receiving conventional medication today still do not possess satisfactory symptom control, indicating a substantial disease burden. Subsequently, based on the type of the autoantibody and the pathogenesis, we synthesized the published material to date and reached a conclusion regarding the literature related to personalized targeted therapy for MG. Novel agents for AChR MG have shown their efficacy in clinical research, such as complement inhibitors, FcRn receptor antagonists, and B-cell activating factor (BAFF) inhibitors. Rituximab, a representative drug of anti-CD20 therapy, has demonstrated benefits in treatment of MuSK MG patients. Due to the existence of low-affinity antibodies or unidentified antibodies that are inaccessible by existing methods, the treatment for seronegative MG remains complicated; thus, special testing and therapy considerations are necessary. It may be advantageous to initiate the application of novel biologicals at an early stage of the disease. Currently, therapies can also be combined and individualized according to different types of antibodies. With such a wide range of drugs, how to tailor treatment strategies to patients with various conditions and find the most suitable solution for each MG profile are our necessary and urgent aims.
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Affiliation(s)
- Chi Ma
- Department of Neurology, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Dan Liu
- Department of Neurology, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Benqiao Wang
- Department of Neurology, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Yingying Yang
- Department of Neurology, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Ruixia Zhu
- Department of Neurology, The First Affiliated Hospital of China Medical University, Shenyang, China
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Dziadkowiak E, Baczyńska D, Waliszewska-Prosół M. MuSK Myasthenia Gravis-Potential Pathomechanisms and Treatment Directed against Specific Targets. Cells 2024; 13:556. [PMID: 38534400 DOI: 10.3390/cells13060556] [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: 02/13/2024] [Revised: 03/17/2024] [Accepted: 03/19/2024] [Indexed: 03/28/2024] Open
Abstract
Myasthenia gravis (MG) is an autoimmune disease in which autoantibodies target structures within the neuromuscular junction, affecting neuromuscular transmission. Muscle-specific tyrosine kinase receptor-associated MG (MuSK-MG) is a rare, often more severe, subtype of the disease with different pathogenesis and specific clinical features. It is characterized by a more severe clinical course, more frequent complications, and often inadequate response to treatment. Here, we review the current state of knowledge about potential pathomechanisms of the MuSK-MG and their therapeutic implications as well as ongoing research in this field, with reference to key points of immune-mediated processes involved in the background of myasthenia gravis.
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Affiliation(s)
- Edyta Dziadkowiak
- Department of Neurology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw, Poland
| | - Dagmara Baczyńska
- Department of Molecular and Cellular Biology, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland
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Vinciguerra C, Bevilacqua L, Lupica A, Ginanneschi F, Piscosquito G, Rini N, Rossi A, Barone P, Brighina F, Di Stefano V. Diagnosis and Management of Seronegative Myasthenia Gravis: Lights and Shadows. Brain Sci 2023; 13:1286. [PMID: 37759888 PMCID: PMC10526522 DOI: 10.3390/brainsci13091286] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 08/30/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Myasthenia gravis (MG) is an antibody-mediated neuromuscular disease affecting the neuromuscular junction. In most cases, autoantibodies can be detected in the sera of MG patients, thus aiding in diagnosis and allowing for early screening. However, there is a small proportion of patients who have no detectable auto-antibodies, a condition termed "seronegative MG" (SnMG). Several factors contribute to this, including laboratory test inaccuracies, decreased antibody production, immunosuppressive therapy, immunodeficiencies, antigen depletion, and immune-senescence. The diagnosis of SnMG is more challenging and is based on clinical features and neurophysiological tests. The early identification of these patients is needed in order to ensure early treatment and prevent complications. This narrative review aims to examine the latest updates on SnMG, defining the clinical characteristics of affected patients, diagnostic methods, management, and therapeutic scenarios.
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Affiliation(s)
- Claudia Vinciguerra
- Neurology Unit, Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84131 Salerno, Italy; (C.V.)
| | - Liliana Bevilacqua
- Neurology Unit, Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84131 Salerno, Italy; (C.V.)
| | - Antonino Lupica
- Neurology Unit, Department of Biomedicine, Neuroscience and Advanced Diagnostics (Bi.N.D.), University of Palermo, 90127 Palermo, Italy (V.D.S.)
| | - Federica Ginanneschi
- Department of Medical, Surgical and Neurological Sciences, University of Siena, 53100 Siena, Italy; (F.G.)
| | - Giuseppe Piscosquito
- Neurology Unit, Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84131 Salerno, Italy; (C.V.)
| | - Nicasio Rini
- Neurology Unit, Department of Biomedicine, Neuroscience and Advanced Diagnostics (Bi.N.D.), University of Palermo, 90127 Palermo, Italy (V.D.S.)
| | - Alessandro Rossi
- Department of Medical, Surgical and Neurological Sciences, University of Siena, 53100 Siena, Italy; (F.G.)
| | - Paolo Barone
- Neurology Unit, Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84131 Salerno, Italy; (C.V.)
| | - Filippo Brighina
- Neurology Unit, Department of Biomedicine, Neuroscience and Advanced Diagnostics (Bi.N.D.), University of Palermo, 90127 Palermo, Italy (V.D.S.)
| | - Vincenzo Di Stefano
- Neurology Unit, Department of Biomedicine, Neuroscience and Advanced Diagnostics (Bi.N.D.), University of Palermo, 90127 Palermo, Italy (V.D.S.)
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Vakrakou AG, Karachaliou E, Chroni E, Zouvelou V, Tzanetakos D, Salakou S, Papadopoulou M, Tzartos S, Voumvourakis K, Kilidireas C, Giannopoulos S, Tsivgoulis G, Tzartos J. Immunotherapies in MuSK-positive Myasthenia Gravis; an IgG4 antibody-mediated disease. Front Immunol 2023; 14:1212757. [PMID: 37564637 PMCID: PMC10410455 DOI: 10.3389/fimmu.2023.1212757] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 07/05/2023] [Indexed: 08/12/2023] Open
Abstract
Muscle-specific kinase (MuSK) Myasthenia Gravis (MG) represents a prototypical antibody-mediated disease characterized by predominantly focal muscle weakness (neck, facial, and bulbar muscles) and fatigability. The pathogenic antibodies mostly belong to the immunoglobulin subclass (Ig)G4, a feature which attributes them their specific properties and pathogenic profile. On the other hand, acetylcholine receptor (AChR) MG, the most prevalent form of MG, is characterized by immunoglobulin (Ig)G1 and IgG3 antibodies to the AChR. IgG4 class autoantibodies are impotent to fix complement and only weakly bind Fc-receptors expressed on immune cells and exert their pathogenicity via interfering with the interaction between their targets and binding partners (e.g. between MuSK and LRP4). Cardinal differences between AChR and MuSK-MG are the thymus involvement (not prominent in MuSK-MG), the distinct HLA alleles, and core immunopathological patterns of pathology in neuromuscular junction, structure, and function. In MuSK-MG, classical treatment options are usually less effective (e.g. IVIG) with the need for prolonged and high doses of steroids difficult to be tapered to control symptoms. Exceptional clinical response to plasmapheresis and rituximab has been particularly observed in these patients. Reduction of antibody titers follows the clinical efficacy of anti-CD20 therapies, a feature implying the role of short-lived plasma cells (SLPB) in autoantibody production. Novel therapeutic monoclonal against B cells at different stages of their maturation (like plasmablasts), or against molecules involved in B cell activation, represent promising therapeutic targets. A revolution in autoantibody-mediated diseases is pharmacological interference with the neonatal Fc receptor, leading to a rapid reduction of circulating IgGs (including autoantibodies), an approach already suitable for AChR-MG and promising for MuSK-MG. New precision medicine approaches involve Chimeric autoantibody receptor T (CAAR-T) cells that are engineered to target antigen-specific B cells in MuSK-MG and represent a milestone in the development of targeted immunotherapies. This review aims to provide a detailed update on the pathomechanisms involved in MuSK-MG (cellular and humoral aberrations), fostering the understanding of the latest indications regarding the efficacy of different treatment strategies.
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Affiliation(s)
- Aigli G. Vakrakou
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Eleni Karachaliou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Elisabeth Chroni
- Department of Neurology, School of Medicine, University of Patras, Patras, Greece
| | - Vasiliki Zouvelou
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Dimitrios Tzanetakos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Stavroula Salakou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Marianna Papadopoulou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
- Department of Physiotherapy, University of West Attica, Athens, Greece
| | - Socrates Tzartos
- Tzartos NeuroDiagnostics, Athens, Greece
- Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
- Department of Pharmacy, University of Patras, Patras, Greece
| | - Konstantinos Voumvourakis
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Constantinos Kilidireas
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
- Department of Neurology, Henry Dunant Hospital Center, Athens, Greece
| | - Sotirios Giannopoulos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Georgios Tsivgoulis
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
- Department of Neurology, The University of Tennessee Health Science Center, Memphis, TN, United States
| | - John Tzartos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
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The diagnostic and prognostic utility of repetitive nerve stimulation in patients with myasthenia gravis. Sci Rep 2023; 13:2985. [PMID: 36806815 PMCID: PMC9941475 DOI: 10.1038/s41598-023-30154-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 02/16/2023] [Indexed: 02/22/2023] Open
Abstract
Repetitive nerve stimulation (RNS) is a standard test for the diagnosis of myasthenia gravis (MG), where decrement of compound muscle action potentials (CMAP) corresponds to clinical muscle fatigability. Our aim was to ascertain the diagnostic and prognostic utility of RNS in MG patients. This study included MG patients treated between 01/2000 and 12/2016, with an observational period of at least one year and a minimum of two neurological examinations. Clinical and electrophysiological data were retrospectively gathered from patient records, and CMAP decrement was correlated with autoantibody titers and clinical disease severity at different time points. Ninety-four patients were included, with 88.3% of the cohort testing positive for acetylcholine receptor autoantibodies (AChR-Abs). RNS sensitivity was higher in patients with generalized disease (71.6%) than in purely ocular MG (38.5%). CMAP decrement did not significantly correlate with AChR-Ab titers, nor with clinical symptom severity at the time of testing or last follow up. However, there was a significant correlation between CMAP decrement and the worst recorded clinical status on a group level. RNS testing is more sensitive in generalized disease and AChR-Ab positive patients, but our data do not support RNS as a tool for long-term outcome prediction. Future studies with a prospective study design could help to overcome a number of limiting factors discussed in our study.
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Hoffmann S, Waters P, Jacobson L, Schuelke M, Stenzel W, Ruck T, Lehnerer S, Stascheit F, Preuße C, Meisel A. Autoantibody detection by a live cell-based assay in conventionally antibody-tested triple seronegative Myasthenia gravis. Neuromuscul Disord 2023; 33:139-144. [PMID: 36746691 DOI: 10.1016/j.nmd.2023.01.002] [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: 09/08/2022] [Revised: 01/04/2023] [Accepted: 01/04/2023] [Indexed: 01/07/2023]
Abstract
Autoantibody testing is the mainstay in confirming the diagnosis of autoimmune myasthenia gravis (MG). However, in approximately 15% of patients, antibody testing in clinical routine remains negative (seronegative MG). This study aimed at assessing the prevalence of "clustered" AChR- and MuSK- and LRP4- autoantibodies using a live cell-based assay in a large German cohort of seronegative myasthenia gravis (SNMG) patients. A total of 67 SNMG patients were included. Clustered AChR-ab were identified in 4.5% (n = 3) of patients. Two out of the three patients showed binding to the adult AchR as well as the fetal AchR. None of the patients was positive for MuSK- or LRP4-autoantibodies. There were no differences in clinical characteristics between the patients with and without clustered AChR-ab detection. Comparison of clinical data of our cohort with clinical data from the nationwide Myasthenia gravis registry showed broad similarities between seronegative MG patients of both cohorts.
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Affiliation(s)
- Sarah Hoffmann
- Department of Neurology and NeuroCure Clinical Research Center, Charité - Universitätsmedizin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany.
| | - Patrick Waters
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Leslie Jacobson
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Markus Schuelke
- Department of Neuropediatrics and NeuroCure Clinical Research Center, Charité - Universitätsmedizin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Werner Stenzel
- Department of Neuropathology, Charité - Universitätsmedizin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Tobias Ruck
- Department of Neurology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sophie Lehnerer
- Department of Neurology and NeuroCure Clinical Research Center, Charité - Universitätsmedizin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Frauke Stascheit
- Department of Neurology and NeuroCure Clinical Research Center, Charité - Universitätsmedizin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Corinna Preuße
- Department of Neuropathology, Charité - Universitätsmedizin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Andreas Meisel
- Department of Neurology and NeuroCure Clinical Research Center, Charité - Universitätsmedizin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
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Kwon YN, Woodhall M, Sung JJ, Kim KK, Lim YM, Kim H, Kim JE, Baek SH, Kim BJ, Park JS, Seok HY, Kim DS, Kwon O, Park KH, Sohn E, Bae JS, Yoon BN, Kim NH, Ahn SW, Choi K, Oh J, Park HJ, Shin KJ, Lee S, Park J, Kim SH, Seok JI, Bae DW, An JY, Joo IS, Choi SJ, Nam TS, Kim S, Park KJ, Kwon KH, Waters P, Hong YH. Clinical pitfalls and serological diagnostics of MuSK myasthenia gravis. J Neurol 2023; 270:1478-1486. [PMID: 36396811 PMCID: PMC9971039 DOI: 10.1007/s00415-022-11458-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/22/2022] [Accepted: 10/25/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND We aimed to evaluate the diagnostic accuracy of enzyme-linked immunosorbent assay (ELISA) for anti-muscle specific tyrosine kinase (MuSK) antibody (Ab) in a large cohort of anti-acetylcholine receptor (AChR) Ab-negative generalized myasthenia gravis (MG), and also to investigate clinical contexts for the diagnosis of MuSK MG. METHODS A retrospective study of 160 patients with a clinical suspicion of AChR Ab-negative generalized MG was performed. The serum samples were tested for anti-clustered AChR Ab by cell-based assay (CBA), anti-MuSK Ab by ELISA, CBA and/or radioimmunoprecipitation assay (RIPA). Clinical data were compared between anti-MuSK Ab-positive MG and double seronegative (AChR and MuSK) MG groups. RESULTS After excluding non-MG and clustered AChR Ab-positive patients, we identified 89 patients as a cohort of AChR Ab-negative generalized MG. Anti-MuSK Ab was positive by ELISA in 22 (24.7%) patients. While CBA identified five additional anti-MuSK Ab-positive patients, the results of ELISA were mostly consistent with CBA and RIPA with Cohen's kappa of 0.80 and 0.90, respectively (p < 0.001). The most frequent differential diagnosis was motor neuron disease particularly of bulbar onset which showed remarkably overlapping clinical and electrophysiological features with MuSK MG at presentation. CONCLUSION While confirming the highest sensitivity of CBA for detecting anti-MuSK Ab, our results highlight the clinical pitfalls in making a diagnosis of MuSK MG and may support a diagnostic utility of MuSK-ELISA in clinical practice.
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Affiliation(s)
- Young Nam Kwon
- Department of Neurology, Seoul National University Seoul Metropolitan Government Boramae Medical Center, Seoul, Republic of Korea
- Department of Neurology, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Mark Woodhall
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, Neuroimmunology Group, University of Oxford, John Radcliffe Hospital, Level 5, West Wing, Headley Way, Oxford, OX3 9DU, UK
| | - Jung-Joon Sung
- Department of Neurology, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Neurology, Seoul National University College of Medicine, Neuroscience Research Institute, Seoul National University Medical Research Council, 20 Boramae-Ro 5-Gil, Dongjak-Gu, Seoul, 07061, Republic of Korea
| | - Kwang-Kuk Kim
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Young-Min Lim
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Hyunjin Kim
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Jee-Eun Kim
- Department of Neurology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Seol-Hee Baek
- Department of Neurology, Korea University College of Medicine, Korea University Anam Hospital, Seoul, Republic of Korea
| | - Byung-Jo Kim
- Department of Neurology, Korea University College of Medicine, Korea University Anam Hospital, Seoul, Republic of Korea
| | - Jin-Sung Park
- Department of Neurology, School of Medicine, Kyungpook National University, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea
| | - Hung Youl Seok
- Department of Neurology, Dongsan Hospital, Keimyung University School of Medicine, Daegu, Republic of Korea
| | - Dae-Seong Kim
- Department of Neurology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea
| | - Ohyun Kwon
- Department of Neurology, Uijeongbu Eulji Medical Center, Eulji University School of Medicine, Uijeongbu, Republic of Korea
| | - Kee Hong Park
- Department of Neurology, Seoul Medical Center, Seoul, Republic of Korea
| | - Eunhee Sohn
- Department of Neurology, Chungnam National University College of Medicine, Chungnam National University Hospital, Daejeon, Republic of Korea
| | - Jong Seok Bae
- Department of Neurology, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Republic of Korea
| | - Byung-Nam Yoon
- Department of Neurology, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Republic of Korea
| | - Nam-Hee Kim
- Department of Neurology, Dongguk University Ilsan Hospital, Goyang, Republic of Korea
| | - Suk-Won Ahn
- Department of Neurology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea
| | - Kyomin Choi
- Department of Neurology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Republic of Korea
| | - Jeeyoung Oh
- Department of Neurology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Republic of Korea
| | - Hyung Jun Park
- Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Kyong Jin Shin
- Department of Neurology, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Republic of Korea
| | - Sanggon Lee
- Department of Neurology, Hanyang University College of Medicine, Seoul, Republic of Korea
| | - Jinseok Park
- Department of Neurology, Hanyang University College of Medicine, Seoul, Republic of Korea
| | - Seung Hyun Kim
- Department of Neurology, Hanyang University College of Medicine, Seoul, Republic of Korea
| | - Jung Im Seok
- Department of Neurology, School of Medicine, Catholic University of Daegu, Daegu, Republic of Korea
| | - Dae Woong Bae
- Department of Neurology, College of Medicine, St. Vincent Hospital, The Catholic University of Korea, Suwon, Republic of Korea
| | - Jae Young An
- Department of Neurology, College of Medicine, St. Vincent Hospital, The Catholic University of Korea, Suwon, Republic of Korea
| | - In Soo Joo
- Department of Neurology, Ajou University School of Medicine, Suwon, Republic of Korea
| | - Seok-Jin Choi
- Department of Neurology, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Tai-Seung Nam
- Department of Neurology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Sunyoung Kim
- Department of Neurology, University of Ulsan College of Medicine, Ulsan, Republic of Korea
| | - Ki-Jong Park
- Department of Neurology, College of Medicine, Gyeongsang National University, Gyeonsang Institute of Health Science, Jinju, Republic of Korea
| | - Ki-Han Kwon
- Department of Neurology, Hallym University Dongtan Sacred Heart Hospital, Hallym University College of Medicine, Hwaseong, Republic of Korea
| | - Patrick Waters
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, Neuroimmunology Group, University of Oxford, John Radcliffe Hospital, Level 5, West Wing, Headley Way, Oxford, OX3 9DU, UK.
| | - Yoon-Ho Hong
- Department of Neurology, Seoul National University Seoul Metropolitan Government Boramae Medical Center, Seoul, Republic of Korea.
- Department of Neurology, Seoul National University College of Medicine, Neuroscience Research Institute, Seoul National University Medical Research Council, 20 Boramae-Ro 5-Gil, Dongjak-Gu, Seoul, 07061, Republic of Korea.
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10
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Spagni G, Gastaldi M, Businaro P, Chemkhi Z, Carrozza C, Mascagna G, Falso S, Scaranzin S, Franciotta D, Evoli A, Damato V. Comparison of Fixed and Live Cell-Based Assay for the Detection of AChR and MuSK Antibodies in Myasthenia Gravis. NEUROLOGY(R) NEUROIMMUNOLOGY & NEUROINFLAMMATION 2023; 10:10/1/e200038. [PMID: 36270951 PMCID: PMC9621337 DOI: 10.1212/nxi.0000000000200038] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 08/18/2022] [Indexed: 11/05/2022]
Abstract
BACKGROUND AND OBJECTIVES Live cell-based assay (CBA) can detect acetylcholine receptors (AChRs) or muscle-specific tyrosine kinase (MuSK) antibodies (Abs) in a proportion of patients with radioimmunoassay (RIA)-double seronegative myasthenia gravis (dSN-MG). A commercial fixed CBA for AChR and MuSK Abs has recently become available; however, comparative studies on fixed and live CBAs are lacking. In this study, we compared the performance of fixed and live CBAs in patients with RIA-dSN MG and assessed their sensitivity in RIA-positive MG samples and their specificity. METHODS AChR and MuSK Abs were tested in 292 serum samples from 2 Italian MG referral centers by live and fixed CBAs: 192 from patients with MG and 100 from controls. All samples had been previously assessed by RIA: 66 were AChR positive, 40 MuSK positive, and 86 dSN. All controls were negative. Two independent raters assessed the CBA results. Fixed and live CBAs were compared with the McNemar test; interrater and interlaboratory agreement were assessed with Cohen's kappa or interclass correlation coefficient (ICC), as appropriate. RESULTS In 86 RIA-dSN samples, fixed CBA detected Abs in 10 cases (11.6%, 95% CI 5.7-20.3), whereas live CBA detected Abs in 16 (18.6%, 95% CI 11.0-28.5) (p = 0.0143). Of these sera, those positive by fixed CBA were also positive by live CBA. In addition, live CBA could detect MuSK Abs in 4 and AChR Abs in 2 samples that were negative by fixed CBA, providing an 8% (95% CI 2.9-16.6) further increase in the Ab detection rate. These results were confirmed by flow cytometry. In the RIA-positive cohort, the sensitivity for AChR Abs was 98.5% (95% CI 91.9%-99.9%) for fixed CBA and 100% (95% CI 94.6-100) for live CBA (p = 0.1573). For both assays, the sensitivity for MuSK Abs was 100% (95% CI 91.2-100), and the specificity was 100% (95% CI 96.4-100). Interrater agreement was almost perfect for live and fixed CBAs (Cohen's kappa 0.972 and 0.978, respectively), alike interlaboratory agreement. Interrater agreement for the CBA score ranged from good to excellent (ICC: 0.832-0.973). DISCUSSION Fixed CBA represents a valuable alternative to RIA for AChR and MuSK Ab detection in patients with MG and could be considered as a first-step diagnostic test. Live CBA can be useful in the serologic evaluation of RIA- and fixed CBA-negative samples.
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Affiliation(s)
- Gregorio Spagni
- From the Department of Neuroscience (G.S., Z.C., S.F., A.E., V.D.), Università Cattolica del Sacro Cuore; Fondazione Policlinico Universitario "A. Gemelli" IRCCS (G.S., A.E.), Rome; Neuroimmunology Laboratory (M.G., P.B., S.S.), IRCCS Mondino Foundation; Department of Brain and Behavioral Sciences (P.B.), University of Pavia, Italy; Chemistry, Biochemistry and Clinical Molecular Biology Unit (C.C., G.M.), Fondazione Policlinico "Gemelli," IRCCS, Rome; Autoimmunology Laboratory (D.F.), IRCCS Ospedale Policlinico San Martino, Genoa; and Department of Neurosciences, Drugs and Child Health (V.D.), University of Florence, Italy
| | - Matteo Gastaldi
- From the Department of Neuroscience (G.S., Z.C., S.F., A.E., V.D.), Università Cattolica del Sacro Cuore; Fondazione Policlinico Universitario "A. Gemelli" IRCCS (G.S., A.E.), Rome; Neuroimmunology Laboratory (M.G., P.B., S.S.), IRCCS Mondino Foundation; Department of Brain and Behavioral Sciences (P.B.), University of Pavia, Italy; Chemistry, Biochemistry and Clinical Molecular Biology Unit (C.C., G.M.), Fondazione Policlinico "Gemelli," IRCCS, Rome; Autoimmunology Laboratory (D.F.), IRCCS Ospedale Policlinico San Martino, Genoa; and Department of Neurosciences, Drugs and Child Health (V.D.), University of Florence, Italy
| | - Pietro Businaro
- From the Department of Neuroscience (G.S., Z.C., S.F., A.E., V.D.), Università Cattolica del Sacro Cuore; Fondazione Policlinico Universitario "A. Gemelli" IRCCS (G.S., A.E.), Rome; Neuroimmunology Laboratory (M.G., P.B., S.S.), IRCCS Mondino Foundation; Department of Brain and Behavioral Sciences (P.B.), University of Pavia, Italy; Chemistry, Biochemistry and Clinical Molecular Biology Unit (C.C., G.M.), Fondazione Policlinico "Gemelli," IRCCS, Rome; Autoimmunology Laboratory (D.F.), IRCCS Ospedale Policlinico San Martino, Genoa; and Department of Neurosciences, Drugs and Child Health (V.D.), University of Florence, Italy
| | - Zeineb Chemkhi
- From the Department of Neuroscience (G.S., Z.C., S.F., A.E., V.D.), Università Cattolica del Sacro Cuore; Fondazione Policlinico Universitario "A. Gemelli" IRCCS (G.S., A.E.), Rome; Neuroimmunology Laboratory (M.G., P.B., S.S.), IRCCS Mondino Foundation; Department of Brain and Behavioral Sciences (P.B.), University of Pavia, Italy; Chemistry, Biochemistry and Clinical Molecular Biology Unit (C.C., G.M.), Fondazione Policlinico "Gemelli," IRCCS, Rome; Autoimmunology Laboratory (D.F.), IRCCS Ospedale Policlinico San Martino, Genoa; and Department of Neurosciences, Drugs and Child Health (V.D.), University of Florence, Italy
| | - Cinzia Carrozza
- From the Department of Neuroscience (G.S., Z.C., S.F., A.E., V.D.), Università Cattolica del Sacro Cuore; Fondazione Policlinico Universitario "A. Gemelli" IRCCS (G.S., A.E.), Rome; Neuroimmunology Laboratory (M.G., P.B., S.S.), IRCCS Mondino Foundation; Department of Brain and Behavioral Sciences (P.B.), University of Pavia, Italy; Chemistry, Biochemistry and Clinical Molecular Biology Unit (C.C., G.M.), Fondazione Policlinico "Gemelli," IRCCS, Rome; Autoimmunology Laboratory (D.F.), IRCCS Ospedale Policlinico San Martino, Genoa; and Department of Neurosciences, Drugs and Child Health (V.D.), University of Florence, Italy
| | - Giovanni Mascagna
- From the Department of Neuroscience (G.S., Z.C., S.F., A.E., V.D.), Università Cattolica del Sacro Cuore; Fondazione Policlinico Universitario "A. Gemelli" IRCCS (G.S., A.E.), Rome; Neuroimmunology Laboratory (M.G., P.B., S.S.), IRCCS Mondino Foundation; Department of Brain and Behavioral Sciences (P.B.), University of Pavia, Italy; Chemistry, Biochemistry and Clinical Molecular Biology Unit (C.C., G.M.), Fondazione Policlinico "Gemelli," IRCCS, Rome; Autoimmunology Laboratory (D.F.), IRCCS Ospedale Policlinico San Martino, Genoa; and Department of Neurosciences, Drugs and Child Health (V.D.), University of Florence, Italy
| | - Silvia Falso
- From the Department of Neuroscience (G.S., Z.C., S.F., A.E., V.D.), Università Cattolica del Sacro Cuore; Fondazione Policlinico Universitario "A. Gemelli" IRCCS (G.S., A.E.), Rome; Neuroimmunology Laboratory (M.G., P.B., S.S.), IRCCS Mondino Foundation; Department of Brain and Behavioral Sciences (P.B.), University of Pavia, Italy; Chemistry, Biochemistry and Clinical Molecular Biology Unit (C.C., G.M.), Fondazione Policlinico "Gemelli," IRCCS, Rome; Autoimmunology Laboratory (D.F.), IRCCS Ospedale Policlinico San Martino, Genoa; and Department of Neurosciences, Drugs and Child Health (V.D.), University of Florence, Italy
| | - Silvia Scaranzin
- From the Department of Neuroscience (G.S., Z.C., S.F., A.E., V.D.), Università Cattolica del Sacro Cuore; Fondazione Policlinico Universitario "A. Gemelli" IRCCS (G.S., A.E.), Rome; Neuroimmunology Laboratory (M.G., P.B., S.S.), IRCCS Mondino Foundation; Department of Brain and Behavioral Sciences (P.B.), University of Pavia, Italy; Chemistry, Biochemistry and Clinical Molecular Biology Unit (C.C., G.M.), Fondazione Policlinico "Gemelli," IRCCS, Rome; Autoimmunology Laboratory (D.F.), IRCCS Ospedale Policlinico San Martino, Genoa; and Department of Neurosciences, Drugs and Child Health (V.D.), University of Florence, Italy
| | - Diego Franciotta
- From the Department of Neuroscience (G.S., Z.C., S.F., A.E., V.D.), Università Cattolica del Sacro Cuore; Fondazione Policlinico Universitario "A. Gemelli" IRCCS (G.S., A.E.), Rome; Neuroimmunology Laboratory (M.G., P.B., S.S.), IRCCS Mondino Foundation; Department of Brain and Behavioral Sciences (P.B.), University of Pavia, Italy; Chemistry, Biochemistry and Clinical Molecular Biology Unit (C.C., G.M.), Fondazione Policlinico "Gemelli," IRCCS, Rome; Autoimmunology Laboratory (D.F.), IRCCS Ospedale Policlinico San Martino, Genoa; and Department of Neurosciences, Drugs and Child Health (V.D.), University of Florence, Italy
| | - Amelia Evoli
- From the Department of Neuroscience (G.S., Z.C., S.F., A.E., V.D.), Università Cattolica del Sacro Cuore; Fondazione Policlinico Universitario "A. Gemelli" IRCCS (G.S., A.E.), Rome; Neuroimmunology Laboratory (M.G., P.B., S.S.), IRCCS Mondino Foundation; Department of Brain and Behavioral Sciences (P.B.), University of Pavia, Italy; Chemistry, Biochemistry and Clinical Molecular Biology Unit (C.C., G.M.), Fondazione Policlinico "Gemelli," IRCCS, Rome; Autoimmunology Laboratory (D.F.), IRCCS Ospedale Policlinico San Martino, Genoa; and Department of Neurosciences, Drugs and Child Health (V.D.), University of Florence, Italy.
| | - Valentina Damato
- From the Department of Neuroscience (G.S., Z.C., S.F., A.E., V.D.), Università Cattolica del Sacro Cuore; Fondazione Policlinico Universitario "A. Gemelli" IRCCS (G.S., A.E.), Rome; Neuroimmunology Laboratory (M.G., P.B., S.S.), IRCCS Mondino Foundation; Department of Brain and Behavioral Sciences (P.B.), University of Pavia, Italy; Chemistry, Biochemistry and Clinical Molecular Biology Unit (C.C., G.M.), Fondazione Policlinico "Gemelli," IRCCS, Rome; Autoimmunology Laboratory (D.F.), IRCCS Ospedale Policlinico San Martino, Genoa; and Department of Neurosciences, Drugs and Child Health (V.D.), University of Florence, Italy
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11
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Lenti MV, Rossi CM, Melazzini F, Gastaldi M, Bugatti S, Rotondi M, Bianchi PI, Gentile A, Chiovato L, Montecucco C, Corazza GR, Di Sabatino A. Seronegative autoimmune diseases: A challenging diagnosis. Autoimmun Rev 2022; 21:103143. [PMID: 35840037 DOI: 10.1016/j.autrev.2022.103143] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 07/10/2022] [Indexed: 12/19/2022]
Abstract
Autoimmune diseases (AID) are increasingly prevalent conditions which comprise more than 100 distinct clinical entities that are responsible for a great disease burden worldwide. The early recognition of these diseases is key for preventing their complications and for tailoring proper management. In most cases, autoantibodies, regardless of their potential pathogenetic role, can be detected in the serum of patients with AID, helping clinicians in making a definitive diagnosis and allowing screening strategies for early -and sometimes pre-clinical- diagnosis. Despite their undoubted crucial role, in a minority of cases, patients with AID may not show any autoantibody, a condition that is referred to as seronegative AID. Suboptimal accuracy of the available laboratory tests, antibody absorption, immunosuppressive therapy, immunodeficiencies, antigen exhaustion, and immunosenescence are the main possible determinants of seronegative AID. Indeed, in seronegative AID, the diagnosis is more challenging and must rely on clinical features and on other available tests, often including histopathological evaluation and radiological diagnostic tests. In this review, we critically dissect, in a narrative fashion, the possible causes of seronegativity, as well as the diagnostic and management implications, in several AID including autoimmune gastritis, celiac disease, autoimmune liver disease, rheumatoid arthritis, autoimmune encephalitis, myasthenia gravis, Sjögren's syndrome, antiphospholipid syndrome, and autoimmune thyroid diseases.
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Affiliation(s)
- Marco Vincenzo Lenti
- Department of Internal Medicine and Medical Therapeutics, University of Pavia, Pavia, Italy; Department of Internal Medicine, IRCCS San Matteo Hospital Foundation, Pavia, Italy
| | - Carlo Maria Rossi
- Department of Internal Medicine and Medical Therapeutics, University of Pavia, Pavia, Italy; Department of Internal Medicine, IRCCS San Matteo Hospital Foundation, Pavia, Italy
| | - Federica Melazzini
- Department of Internal Medicine and Medical Therapeutics, University of Pavia, Pavia, Italy; Department of Internal Medicine, IRCCS San Matteo Hospital Foundation, Pavia, Italy
| | - Matteo Gastaldi
- Neuroimmunology Laboratory, IRCCS Mondino Foundation, Pavia, Italy
| | - Serena Bugatti
- Department of Internal Medicine and Medical Therapeutics, University of Pavia, Pavia, Italy; Unit of Rheumatology, IRCCS San Matteo Hospital Foundation, Pavia, Italy
| | - Mario Rotondi
- Department of Internal Medicine and Medical Therapeutics, University of Pavia, Pavia, Italy; Istituti Clinici Scientifici Maugeri IRCCS, Unit of Internal Medicine and Endocrinology, Laboratory for Endocrine Disruptors, Pavia, Italy
| | - Paola Ilaria Bianchi
- Department of Internal Medicine, IRCCS San Matteo Hospital Foundation, Pavia, Italy
| | - Antonella Gentile
- Department of Internal Medicine and Medical Therapeutics, University of Pavia, Pavia, Italy; Department of Internal Medicine, IRCCS San Matteo Hospital Foundation, Pavia, Italy
| | - Luca Chiovato
- Department of Internal Medicine and Medical Therapeutics, University of Pavia, Pavia, Italy; Istituti Clinici Scientifici Maugeri IRCCS, Unit of Internal Medicine and Endocrinology, Laboratory for Endocrine Disruptors, Pavia, Italy
| | - Carlomaurizio Montecucco
- Department of Internal Medicine and Medical Therapeutics, University of Pavia, Pavia, Italy; Unit of Rheumatology, IRCCS San Matteo Hospital Foundation, Pavia, Italy
| | - Gino Roberto Corazza
- Department of Internal Medicine and Medical Therapeutics, University of Pavia, Pavia, Italy; Department of Internal Medicine, IRCCS San Matteo Hospital Foundation, Pavia, Italy
| | - Antonio Di Sabatino
- Department of Internal Medicine and Medical Therapeutics, University of Pavia, Pavia, Italy; Department of Internal Medicine, IRCCS San Matteo Hospital Foundation, Pavia, Italy.
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12
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Wang S, Yang H, Guo R, Wang L, Zhang Y, Lv J, Zhao X, Zhang J, Fang H, Zhang Q, Zhang Y, Yang J, Cui X, Gao P, Chang T, Gao F. Antibodies to Full-Length Agrin Protein in Chinese Patients With Myasthenia Gravis. Front Immunol 2021; 12:753247. [PMID: 34956185 PMCID: PMC8692888 DOI: 10.3389/fimmu.2021.753247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 11/19/2021] [Indexed: 11/13/2022] Open
Abstract
This study aimed to establish a cell-based assay (CBA) for the detection of agrin antibodies (Agrin-Ab) to explore the clinical features of agrin antibody-positive Chinese patients with myasthenia gravis (Agrin-MG). We developed a CBA based on the human full-length agrin protein expressed in HEK293T cells for the reliable and efficient detection of Agrin-Ab. Clinical data and serum samples were collected from 1948 MG patients in 26 provinces in China. The demographic and clinical features of Agrin-MG patients were compared with those of other MG patient subsets. Eighteen Agrin-MG cases were identified from 1948 MG patients. Nine patients were Agrin-Ab positive, and nine were AChR-Ab and Agrin-Ab double-positive (Agrin/AChR-MG). Eleven (61.11%) patients were males older than 40 years of age. The initial symptom in 13 (81.25%) cases was ocular weakness. Occasionally, the initial symptom was limb-girdle weakness (two cases) or bulbar muscle weakness (one case). Agrin-MG patients demonstrated slight improvement following treatment with either acetylcholinesterase inhibitor or prednisone; however, the combination of the two drugs could effectively relieve MG symptoms. In China, Agrin-MG demonstrated seropositivity rates of 0.92%. These patients were commonly middle-aged or elderly men. The patients usually presented weakness in the ocular, bulbar, and limb muscles, which may be combined with thymoma. These patients have more severe diseases, although the combination of pyridostigmine and prednisone was usually effective in relieving symptoms.
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Affiliation(s)
- Shumin Wang
- Department of Neuroimmunology, Henan Institute of Medical and Pharmaceutical Sciences, Academy of Medical Science, Zhengzhou University, Zhengzhou, China
| | - Haonan Yang
- Department of Neuroimmunology, Henan Institute of Medical and Pharmaceutical Sciences, Academy of Medical Science, Zhengzhou University, Zhengzhou, China.,BGI College, Zhengzhou University, Zhengzhou, China
| | - Rongjing Guo
- Department of Neurology, Tangdu Hospital, The Air Force Medical University, Xi'an, China
| | - Lulu Wang
- Department of Neuroimmunology, Henan Institute of Medical and Pharmaceutical Sciences, Academy of Medical Science, Zhengzhou University, Zhengzhou, China.,Department of Neurology, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yingna Zhang
- Department of Neuroimmunology, Henan Institute of Medical and Pharmaceutical Sciences, Academy of Medical Science, Zhengzhou University, Zhengzhou, China
| | - Jie Lv
- Department of Neuroimmunology, Henan Institute of Medical and Pharmaceutical Sciences, Academy of Medical Science, Zhengzhou University, Zhengzhou, China
| | - Xue Zhao
- Department of Neuroimmunology, Henan Institute of Medical and Pharmaceutical Sciences, Academy of Medical Science, Zhengzhou University, Zhengzhou, China
| | - Jing Zhang
- Department of Neuroimmunology, Henan Institute of Medical and Pharmaceutical Sciences, Academy of Medical Science, Zhengzhou University, Zhengzhou, China
| | - Hua Fang
- Department of Neuroimmunology, Henan Institute of Medical and Pharmaceutical Sciences, Academy of Medical Science, Zhengzhou University, Zhengzhou, China
| | - Qingyong Zhang
- Myasthenia Gravis Comprehensive Diagnosis and Treatment Center, Henan Provincial People's Hospital, Zhengzhou, China
| | - Yunke Zhang
- Department of Encephalopathy, First Affiliated Hospital of Henan University of Traditional Chinese Medicine (TCM), Zhengzhou, China
| | - Junhong Yang
- Department of Encephalopathy, First Affiliated Hospital of Henan University of Traditional Chinese Medicine (TCM), Zhengzhou, China
| | - Xinzheng Cui
- Myasthenia Gravis Comprehensive Diagnosis and Treatment Center, Henan Provincial People's Hospital, Zhengzhou, China
| | - Peiyang Gao
- Department of Neuroimmunology, Henan Institute of Medical and Pharmaceutical Sciences, Academy of Medical Science, Zhengzhou University, Zhengzhou, China
| | - Ting Chang
- Department of Neurology, Tangdu Hospital, The Air Force Medical University, Xi'an, China
| | - Feng Gao
- Department of Neuroimmunology, Henan Institute of Medical and Pharmaceutical Sciences, Academy of Medical Science, Zhengzhou University, Zhengzhou, China
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13
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Park G, Kesserwani H. Seropositive Muscle-Specific Tyrosine Kinase Myasthenia Gravis Presenting as a Late-Onset Isolated Sixth Nerve Palsy: A Case Report and a Brief Review of Subtypes of Myasthenia Gravis. Cureus 2021; 13:e19701. [PMID: 34934570 PMCID: PMC8684330 DOI: 10.7759/cureus.19701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2021] [Indexed: 11/30/2022] Open
Abstract
Autoimmune myasthenia gravis (MG) is a well-characterized post-synaptic disorder of neuromuscular transmission. Immunologically, there is complement activation with autoantibodies binding to the acetylcholine receptor (AChR), leading to cross-linking and internalization of the receptor. The diminished functional clustering leads to impaired folding of the post-synaptic membrane. The antibodies generated by the autoimmune process are directed at the various components of the post-synaptic membrane and its scaffolding, including the AChR, muscle-specific tyrosine kinase (MuSK), low-density lipoprotein receptor-related protein 4 (LRP4), and the other recently described epitopes including the extracellular membrane proteins agrin and collagen Q (ColQ). MuSK MG is phenotypically different from classic AChR-antibody-mediated MG by a more frequent presentation of bulbar weakness, less responsiveness to symptomatic therapy with acetylcholinesterase inhibitors, the absence of a thymoma, and a better therapeutic response to a cluster of differentiation (CD-20) B-cell therapy such as rituximab. The pleiotropic ocular findings of ocular MG include ptosis, fluctuating and variable involvement of cranial nerves III, IV, and VI, pseudo-internuclear ophthalmoplegia (INO), near-complete or complete ophthalmoplegia, and variable gaze palsies. To our knowledge, we present one of the very few reported cases of MuSK MG presenting as isolated sixth nerve palsy. The localization of a sixth nerve palsy with lateral rectus muscle weakness can be due to disease anywhere along its path from the abducens nucleus, coursing at the skull base through Dorello's canal, through the cavernous sinus, and along its path through the superior orbital fissure and into the orbits. A painless sixth nerve palsy should alert the clinician to MuSK-MG as we outline in this case report.
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Affiliation(s)
- Gyusik Park
- Neurology, University of Alabama at Birmingham School of Medicine, Birmingham, USA
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14
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Basile U, Napodano C, Gulli F, Pocino K, Di Santo R, Todi L, Basile V, Provenzano C, Ciasca G, Marino M. Laboratory Investigation of Hybrid IgG4 k/λ in MuSK Positive Myasthenia Gravis. Int J Mol Sci 2021; 22:ijms22179142. [PMID: 34502051 PMCID: PMC8430634 DOI: 10.3390/ijms22179142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 08/03/2021] [Accepted: 08/14/2021] [Indexed: 12/29/2022] Open
Abstract
Myasthenia gravis with antibodies (Abs) against the muscle-specific tyrosine kinase (MuSK) is a rare autoimmune disorder (AD) of the neuromuscular junction (NMJ) and represents a prototype of AD with proven IgG4-mediated pathogenicity. Thanks to the mechanism of Fab-arm exchange (FAE) occurring in vivo, resulting MuSK IgG4 k/λ Abs increase their interference on NMJ and pathogenicity. The characterization of hybrid MuSK IgG4 as a biomarker for MG management is poorly investigated. Here, we evaluated total IgG4, hybrid IgG4 k/λ, and the hybrid/total ratio in 14 MuSK-MG sera in comparison with 24 from MG with Abs against acetylcholine receptor (AChR) that represents the not IgG4-mediated MG form. In both subtypes of MG, we found that the hybrid/total ratio reflects distribution reported in normal individuals; instead, when we correlated the hybrid/total ratio with specific immune-reactivity we found a positive correlation only with anti-MuSK titer, with a progressive increase of hybrid/total mean values with increasing disease severity, indirectly confirming that most part of hybrid IgG4 molecules are engaged in the anti-MuSK pathogenetic immune-reactivity. Further analysis is necessary to strengthen the significance of this less unknown biomarker, but we retain it is full of a diagnostic-prognostic powerful potential for the management of MuSK-MG.
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Affiliation(s)
- Umberto Basile
- Dipartimento di Scienze di Laboratorio e Infettivologiche, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, Università Cattolica del Sacro Cuore, 00168 Rome, Italy;
| | | | - Francesca Gulli
- Laboratorio di Patologia Clinica, Ospedale Madre Giuseppina Vannini, 00177 Rome, Italy;
| | - Krizia Pocino
- Unità Operativa Complessa Patologia Clinica, Ospedale Generale di Zona, San Pietro Fatebenefratelli, 00189 Rome, Italy;
| | - Riccardo Di Santo
- Dipartimento di Neuroscienze, Sezione di Fisica, Fondazione Policlinico “A. Gemelli” IRCCS, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (R.D.S.); (G.C.)
| | - Laura Todi
- Dipartimento di Medicina e Chirurgia Traslazionale, Sezione di Patologia Generale, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (L.T.); (C.P.)
| | - Valerio Basile
- Clinical Pathology Unit and Cancer Biobank, Department of Research, Advanced Diagnostics and Technological Innovation, IFO-Regina Elena National Cancer Institute, 00128 Rome, Italy;
| | - Carlo Provenzano
- Dipartimento di Medicina e Chirurgia Traslazionale, Sezione di Patologia Generale, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (L.T.); (C.P.)
| | - Gabriele Ciasca
- Dipartimento di Neuroscienze, Sezione di Fisica, Fondazione Policlinico “A. Gemelli” IRCCS, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (R.D.S.); (G.C.)
| | - Mariapaola Marino
- Dipartimento di Medicina e Chirurgia Traslazionale, Sezione di Patologia Generale, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (L.T.); (C.P.)
- Correspondence:
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15
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Evoli A, Spagni G, Monte G, Damato V. Heterogeneity in myasthenia gravis: considerations for disease management. Expert Rev Clin Immunol 2021; 17:761-771. [PMID: 34043932 DOI: 10.1080/1744666x.2021.1936500] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Introduction: Myasthenia gravis is a rare disease of the neuromuscular junction and a prototype of B cell-driven immunopathology. Pathogenic antibodies target post-synaptic transmembrane proteins, most commonly the nicotinic acetylcholine receptor and the muscle-specific tyrosine kinase, inducing end-plate alterations and neuromuscular transmission impairment. Several clinical subtypes are distinct on the basis of associated antibodies, age at symptom onset, thymus pathology, genetic factors, and weakness distribution. These subtypes have distinct pathogenesis that can account for different responses to treatment. Conventional therapy is based on the use of symptomatic agents, steroids, immunosuppressants and thymectomy. Of late, biologics have emerged as effective therapeutic options.Areas covered: In this review, we will discuss the management of myasthenia gravis in relation to its phenotypic and biological heterogeneity, in the light of recent advances in the disease immunopathology, new diagnostic tools, and results of clinical trialsExpert opinion: Clinical management is shaped on serological subtype, and patient age at onset, lifestyle and comorbidities, balancing therapeutic needs and safety. Although reliable biomarkers predictive of clinical and biologic outcome are still lacking, recent developments promise a more effective and safe treatment. Disease subtyping according to serological testing and immunopathology is crucial to the appropriateness of clinical management.
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Affiliation(s)
- Amelia Evoli
- Dipartimento di Neuroscienze, Università Cattolica Del Sacro Cuore, Rome, Italy.,Unità Operativa Complessa di Neurologia, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy
| | - Gregorio Spagni
- Dipartimento di Neuroscienze, Università Cattolica Del Sacro Cuore, Rome, Italy
| | - Gabriele Monte
- Dipartimento di Neuroscienze, Università Cattolica Del Sacro Cuore, Rome, Italy
| | - Valentina Damato
- Dipartimento di Neuroscienze, Università Cattolica Del Sacro Cuore, Rome, Italy
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16
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Zografou C, Vakrakou AG, Stathopoulos P. Short- and Long-Lived Autoantibody-Secreting Cells in Autoimmune Neurological Disorders. Front Immunol 2021; 12:686466. [PMID: 34220839 PMCID: PMC8248361 DOI: 10.3389/fimmu.2021.686466] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/28/2021] [Indexed: 12/24/2022] Open
Abstract
As B cells differentiate into antibody-secreting cells (ASCs), short-lived plasmablasts (SLPBs) are produced by a primary extrafollicular response, followed by the generation of memory B cells and long-lived plasma cells (LLPCs) in germinal centers (GCs). Generation of IgG4 antibodies is T helper type 2 (Th2) and IL-4, -13, and -10-driven and can occur parallel to IgE, in response to chronic stimulation by allergens and helminths. Although IgG4 antibodies are non-crosslinking and have limited ability to mobilize complement and cellular cytotoxicity, when self-tolerance is lost, they can disrupt ligand-receptor binding and cause a wide range of autoimmune disorders including neurological autoimmunity. In myasthenia gravis with predominantly IgG4 autoantibodies against muscle-specific kinase (MuSK), it has been observed that one-time CD20+ B cell depletion with rituximab commonly leads to long-term remission and a marked reduction in autoantibody titer, pointing to a short-lived nature of autoantibody-secreting cells. This is also observed in other predominantly IgG4 autoantibody-mediated neurological disorders, such as chronic inflammatory demyelinating polyneuropathy and autoimmune encephalitis with autoantibodies against the Ranvier paranode and juxtaparanode, respectively, and extends beyond neurological autoimmunity as well. Although IgG1 autoantibody-mediated neurological disorders can also respond well to rituximab induction therapy in combination with an autoantibody titer drop, remission tends to be less long-lasting and cases where titers are refractory tend to occur more often than in IgG4 autoimmunity. Moreover, presence of GC-like structures in the thymus of myasthenic patients with predominantly IgG1 autoantibodies against the acetylcholine receptor and in ovarian teratomas of autoimmune encephalitis patients with predominantly IgG1 autoantibodies against the N‐methyl‐d‐aspartate receptor (NMDAR) confers increased the ability to generate LLPCs. Here, we review available information on the short-and long-lived nature of ASCs in IgG1 and IgG4 autoantibody-mediated neurological disorders and highlight common mechanisms as well as differences, all of which can inform therapeutic strategies and personalized medical approaches.
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Affiliation(s)
- C Zografou
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - A G Vakrakou
- First Department of Neurology, National and Kapodistrian University of Athens Medical School, Athens, Greece
| | - P Stathopoulos
- First Department of Neurology, National and Kapodistrian University of Athens Medical School, Athens, Greece
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17
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Gastaldi M, Scaranzin S, Businaro P, Mobilia E, Benedetti L, Pesce G, Franciotta D. Improving laboratory diagnostics in myasthenia gravis. Expert Rev Mol Diagn 2021; 21:579-590. [PMID: 33970749 DOI: 10.1080/14737159.2021.1927715] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Introduction: Myasthenia gravis (MG) is a prototypical autoimmune disease, characterized by pathogenic autoantibodies targeting structures of the neuromuscular junction. Radioimmunoprecipitation assays (RIPAs) represent the gold standard for their detection. However, new methods are emerging to complement, or overcome RIPAs, also with the perspective of eliminating the use of radioactive reagents.Areas covered: We discuss advances in laboratory methods, prompted especially by cell-based assays (CBAs), for the detection of the autoantibodies of MG diagnostics, above all those to the nicotinic acetylcholine receptor (AChR), muscle-specific kinase (MuSK), and low molecular-weight receptor-related low-density lipoprotein-4 (LRP4).Expert opinion: CBA technology makes AChRs aggregate on cell membranes, thus allowing to detect autoantibodies to clustered AChRs, with reduction of seronegative MG cases. The diagnostic relevance of RIPA/CBA-measurable LRP4 antibodies is still unclear, in Caucasian patients at least. Live CBAs for the detection of AChR, MuSK, and LRP4 antibodies might represent an alternative to RIPAs, but first require full validation. CBAs could be used as screening tests, limiting RIPAs for antibody quantification. To this end, ELISAs might be an alternative.Fixation procedures preserving enough degree of antigen conformationality could yield AChR and MuSK CBAs suitable for a wide use in clinical-chemistry laboratories.
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Affiliation(s)
- Matteo Gastaldi
- Neuroimmunology Laboratory, IRCCS Mondino Foundation, Pavia, Italy
| | - Silvia Scaranzin
- Neuroimmunology Laboratory, IRCCS Mondino Foundation, Pavia, Italy
| | - Pietro Businaro
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Emanuela Mobilia
- Autoimmunity Laboratory, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Luana Benedetti
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, Genova, Italy; IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Giampaola Pesce
- Autoimmunity Laboratory, IRCCS Ospedale Policlinico San Martino, Genova, Italy.,Department of Internal Medicine (Dimi), University of Genova, Genova, Italy
| | - Diego Franciotta
- Autoimmunity Laboratory, IRCCS Ospedale Policlinico San Martino, Genova, Italy
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Rousseff RT. Diagnosis of Myasthenia Gravis. J Clin Med 2021; 10:jcm10081736. [PMID: 33923771 PMCID: PMC8073361 DOI: 10.3390/jcm10081736] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 04/09/2021] [Accepted: 04/13/2021] [Indexed: 11/24/2022] Open
Abstract
The diagnosis of autoimmune Myasthenia Gravis (MG) remains clinical and rests on the history and physical findings of fatigable, fluctuating muscle weakness in a specific distribution. Ancillary bedside tests and laboratory methods help confirm the synaptic disorder, define its type and severity, classify MG according to the causative antibodies, and assess the effect of treatment objectively. We present an update on the tests used in the diagnosis and follow-up of MG and the suggested approach for their application.
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Affiliation(s)
- Rossen T. Rousseff
- Department of Neurology, Ibn-Sina Hospital, Sabah Health Area,, Kuwait City 13115, Kuwait; ; Tel.: +359-878-417-412
- Science and Research Institute, Medical University of Pleven, 5800 Pleven, Bulgaria
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19
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Assini A, Gandoglia I, Damato V, Rikani K, Evoli A, Del Sette M. Response to: "MuSK-positive myasthenia may be triggered not only by SARS-CoV-2". Eur J Neurol 2021; 28:e82-e83. [PMID: 33730439 PMCID: PMC8250645 DOI: 10.1111/ene.14827] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 03/05/2021] [Indexed: 12/01/2022]
Affiliation(s)
| | | | - Valentina Damato
- Institute of Neurology, Fondazione Policlinico Universitario 'A. Gemelli' IRCCS, Roma, Italy.,Università Cattolica del Sacro Cuore, Roma, Italy
| | | | - Amelia Evoli
- Institute of Neurology, Fondazione Policlinico Universitario 'A. Gemelli' IRCCS, Roma, Italy.,Università Cattolica del Sacro Cuore, Roma, Italy
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20
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Assini A, Gandoglia I, Damato V, Rikani K, Evoli A, Del Sette M. Myasthenia gravis associated with anti-MuSK antibodies developed after SARS-CoV-2 infection. Eur J Neurol 2021; 28:3537-3539. [PMID: 33421278 PMCID: PMC8014563 DOI: 10.1111/ene.14721] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 12/17/2020] [Accepted: 12/31/2020] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Since the onset of the novel coronavirus pandemic, several neurological complications secondary to SARS-CoV-2 infection have been reported, affecting central nervous system, peripheral nervous system and neuromuscular junction. CASE REPORT We present the case of a 77-year-old man who developed bulbar myasthenia gravis (MG) eight weeks after SARS-CoV-2 infection. The search for serum antibodies against the acetylcholine receptor, the muscle-specific tyrosine kinase (MuSK), and the low-density lipoprotein receptor-related protein 4 antibodies, performed by radioimmunoassay (RIA), resulted negative, while anti-MuSK antibodies were detected by cell-based assay (CBA). The patient was treated with pyridostigmine (60 mg four times a day) with unsatisfactory clinical response, followed by immunosuppressive therapy (azathioprine 1.5 mg/kg/day) with improvement of MG symptoms after two months of treatment. DISCUSSION Several viral diseases have been described as associated with the onset of MG, although the underlying mechanisms are not yet fully understood. Similarly, a growing number of scientific reports suggest a correlation between SARS-CoV-2 infection and autoimmune diseases. The interest of our case lies in the timing of the MG onset (after two months from infection), together with the unusual late onset of anti-MuSK MG. These elements suggest that coronavirus infection may act as a trigger of the disease. We confirm the importance of CBA in the serological diagnosis of RIA-negative MG.
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Affiliation(s)
| | | | - Valentina Damato
- Institute of Neurology, Fondazione Policlinico Universitario 'A. Gemelli' IRCCS, Roma, Italy.,Università Cattolica del Sacro Cuore, Roma, Italy
| | | | - Amelia Evoli
- Institute of Neurology, Fondazione Policlinico Universitario 'A. Gemelli' IRCCS, Roma, Italy.,Università Cattolica del Sacro Cuore, Roma, Italy
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21
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Comparison of N-methyl-D-aspartate receptor antibody assays using live or fixed substrates. J Neurol 2021; 268:1818-1826. [PMID: 33389029 DOI: 10.1007/s00415-020-10329-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/11/2020] [Accepted: 11/19/2020] [Indexed: 12/24/2022]
Abstract
The diagnostic criteria for N-methyl-D-aspartate receptor antibody (NMDAR-Ab) encephalitis require the presence of CSF antibodies against the NMDAR, whereas serum antibodies are considered specific only if accompanied by CSF antibodies. Current assays include in-house immunochemistry (IHC), or cell-based assays (CBA) which use live (L-CBA) or fixed cells (F-CBA), and commercially available fixed-cells CBA (C-CBA), but these have not been compared in parallel. We compared the L-CBA with F-CBA, C-CBA, and IHC using sera and CSFs archived from > 30,000 received for testing and previously positive by L-CBA. Referring neurologists, if identified, provided "definite" or "unlikely" diagnoses of NMDAR-Ab encephalitis for 31 paired serum-CSF samples and 53 unpaired sera. There was good concordance between paired sera and CSFs, with 13/16 "definite" pairs positive, and 7/8 "unlikely" pairs negative in all in-house assays. In unpaired "definite" sera, L-CBA was most sensitive. However, 19/24 serum samples from "unlikely" patients were positive by L-CBA, with only 5/24 and 1/24 positive by F-CBA and IHC, respectively. In available samples, C-CBA demonstrated high sensitivity for CSF, but surprisingly low sensitivity for serum. Overall, regardless of the technique, CSF results were accurate and easy to interpret, but if CSF is unavailable, negative serum C-CBA results in cases with suspected NMDAR-Ab encephalitis could be repeated by a more sensitive in-house assay. Although these assays are sensitive, particularly for CSF, referral of sera with low pre-test probability should be avoided to reduce clinically-irrelevant "false positive" results.
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22
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Kim MJ, Kim SW, Kim M, Choi YC, Kim SM, Shin HY. Evaluating an In-House Cell-Based Assay for Detecting Antibodies Against Muscle-Specific Tyrosine Kinase in Myasthenia Gravis. J Clin Neurol 2021; 17:400-408. [PMID: 34184448 PMCID: PMC8242307 DOI: 10.3988/jcn.2021.17.3.400] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 01/11/2023] Open
Abstract
Background and Purpose Detecting antibodies against muscle-specific tyrosine kinase (MuSK Abs) is essential for diagnosing myasthenia gravis (MG). We applied an in-house cell-based assay (CBA) to detect MuSK Abs. Methods A stable cell line was generated using a lentiviral vector, which allowed the expression of MuSK tagged with green fluorescent protein in human embryonic kidney 293 (HEK293) cells. Serum and anti-human IgG antibody conjugated with red fluorescence were added. The presence of MuSK Abs was determined based on the fluorescence intensity and their colocalization in fluorescence microscopy. Totals of 218 serum samples collected from 177 patients with MG, 31 with other neuromuscular diseases, and 10 healthy controls were analyzed. The CBA results were compared with those of a radioimmunoprecipitation assay (RIPA) and an enzyme-linked immunosorbent assay (ELISA). Results The MuSK-HEK293 cell line stably expressed MuSK protein. The CBA detected MuSK Abs in 34 (19.2%) of 177 samples obtained from patients with MG and in none of the participants having other neuromuscular diseases or in the healthy controls. The clinical characteristics of the patients with MuSK MG determined based on the CBA were strongly correlated with known clinical features of MuSK MG. There was an almost perfect agreement between the results of the CBA and those of the RIPA (Cohen's kappa=0.880, p<0.001) and ELISA (Cohen's kappa=0.982, p<0.001). Conclusions The results of the in-house CBA showed excellent agreement with both the RIPA and ELISA. Our in-house CBA can be considered a reliable method for detecting MuSK Abs.
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Affiliation(s)
- Min Ju Kim
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea.,Graduate Program of Nanoscience and Technology, Yonsei University, Seoul, Korea
| | - Seung Woo Kim
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - MinGi Kim
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - Young Chul Choi
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - Seung Min Kim
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - Ha Young Shin
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea.
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23
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Evoli A, Iorio R. Controversies in Ocular Myasthenia Gravis. Front Neurol 2020; 11:605902. [PMID: 33329368 PMCID: PMC7734350 DOI: 10.3389/fneur.2020.605902] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 10/26/2020] [Indexed: 12/12/2022] Open
Abstract
Myasthenia gravis (MG) with symptoms limited to eye muscles [ocular MG (OMG)] is a rare disease. OMG incidence varies according to ethnicity and age of onset. In recent years, both an increase in incidence rate, particularly in the elderly, and a lower risk for secondary generalization may have contributed to the growing disease prevalence in Western countries. OMG should be considered in patients with painless ptosis and extrinsic ophthalmoparesis. Though asymmetric muscle involvement and symptom fluctuations are typical, in some cases, OMG can mimic isolated cranial nerve paresis, internuclear ophthalmoplegia, and conjugate gaze palsy. Diagnostic confirmation can be challenging in patients negative for anti-acetylcholine receptor and anti-muscle-specific tyrosine kinase antibodies on standard radioimmunoassay. Early treatment is aimed at relieving symptoms and at preventing disease progression to generalized MG. Despite the absence of high-level evidence, there is general agreement on the efficacy of steroids at low to moderate dosage; immunosuppressants are considered when steroid high maintenance doses are required. The role of thymectomy in non-thymoma patients is controversial. Prolonged exposure to immunosuppressive therapy has a negative impact on the health-related quality of life in a proportion of these patients. OMG is currently excluded from most of the treatments recently developed in generalized MG.
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Affiliation(s)
- Amelia Evoli
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy.,Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Raffaele Iorio
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy.,Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
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24
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Lazaridis K, Tzartos SJ. Myasthenia Gravis: Autoantibody Specificities and Their Role in MG Management. Front Neurol 2020; 11:596981. [PMID: 33329350 PMCID: PMC7734299 DOI: 10.3389/fneur.2020.596981] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/30/2020] [Indexed: 12/11/2022] Open
Abstract
Myasthenia gravis (MG) is the most common autoimmune disorder affecting the neuromuscular junction, characterized by skeletal muscle weakness and fatigability. It is caused by autoantibodies targeting proteins of the neuromuscular junction; ~85% of MG patients have autoantibodies against the muscle acetylcholine receptor (AChR-MG), whereas about 5% of MG patients have autoantibodies against the muscle specific kinase (MuSK-MG). In the remaining about 10% of patients no autoantibodies can be found with the classical diagnostics for AChR and MuSK antibodies (seronegative MG, SN-MG). Since serological tests are relatively easy and non-invasive for disease diagnosis, the improvement of methods for the detection of known autoantibodies or the discovery of novel autoantibody specificities to diminish SN-MG and to facilitate differential diagnosis of similar diseases, is crucial. Radioimmunoprecipitation assays (RIPA) are the staple for MG antibody detection, but over the past years, using cell-based assays (CBAs) or improved highly sensitive RIPAs, it has been possible to detect autoantibodies in previously SN-MG patients. This led to the identification of more patients with antibodies to the classical antigens AChR and MuSK and to the third MG autoantigen, the low-density lipoprotein receptor-related protein 4 (LRP4), while antibodies against other extracellular or intracellular targets, such as agrin, Kv1.4 potassium channels, collagen Q, titin, the ryanodine receptor and cortactin have been found in some MG patients. Since the autoantigen targeted determines in part the clinical manifestations, prognosis and response to treatment, serological tests are not only indispensable for initial diagnosis, but also for monitoring treatment efficacy. Importantly, knowing the autoantibody profile of MG patients could allow for more efficient personalized therapeutic approaches. Significant progress has been made over the past years toward the development of antigen-specific therapies, targeting only the specific immune cells or autoantibodies involved in the autoimmune response. In this review, we will present the progress made toward the development of novel sensitive autoantibody detection assays, the identification of new MG autoantigens, and the implications for improved antigen-specific therapeutics. These advancements increase our understanding of MG pathology and improve patient quality of life by providing faster, more accurate diagnosis and better disease management.
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Affiliation(s)
| | - Socrates J Tzartos
- Tzartos NeuroDiagnostics, Athens, Greece.,Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
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25
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Nagaishi A, Narita T, Woodhall M, Jacobson L, Waters P, Irani SR, Vincent A, Matsuo H. Autoantibodies in Japanese patients with ocular myasthenia gravis. Muscle Nerve 2020; 63:262-267. [PMID: 33094484 PMCID: PMC7983878 DOI: 10.1002/mus.27103] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 10/14/2020] [Accepted: 10/18/2020] [Indexed: 12/16/2022]
Abstract
Introduction The majority of patients with myasthenia gravis (MG) initially present with ocular symptoms, but it is difficult to predict which cases will remain as ocular MG (OMG) or will progress to generalized MG. Herein we evaluated the serologic profile of Japanese OMG and its relationship with clinical features. Methods Seventy‐three patients with OMG from five Japanese myasthenia gravis (MG) centers were enrolled. Live cell‐based assays (CBAs) were used to determine the presence of autoantibodies (Abs) to clustered adult (2α, β, δ, ε) and fetal (2α, β, δ, γ) acetylcholine receptor (AChR) isoforms, muscle‐specific receptor tyrosine kinase (MuSK), and lipoprotein receptor–related protein‐4 (LRP4). Results Thirty‐four of 73 (46.5%) serum samples were positive for Abs against both the adult‐type and fetal‐type AChR, as expected, but 7 (9.6%) and 2 (2.7%) were positive only for fetal or adult AChR‐Abs, respectively. Four (5.4%) samples were positive for MuSK‐Abs, but two of these also contained antibodies to fetal AChR or LRP4. Twenty‐six (35.6%) samples were seronegative. Discussion Abs against fetal‐specific AChR, MuSK, and LRP4 are found in some patients with OMG. Future studies attempting to predict conversion from ocular symptoms to generalized MG may benefit from measurement of these antibodies.
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Affiliation(s)
- Akiko Nagaishi
- Department of Neurology, Nagasaki Kawatana Medical Center, Nagasaki, Japan.,Nuffield Department of Clinical Neurosciences, Oxford Autoimmune Neurology Group, University of Oxford, Oxford, UK
| | - Tomoko Narita
- Department of Neurology, Nagasaki Kawatana Medical Center, Nagasaki, Japan
| | - Mark Woodhall
- Nuffield Department of Clinical Neurosciences, Oxford Autoimmune Neurology Group, University of Oxford, Oxford, UK
| | - Leslie Jacobson
- Nuffield Department of Clinical Neurosciences, Oxford Autoimmune Neurology Group, University of Oxford, Oxford, UK
| | - Patrick Waters
- Nuffield Department of Clinical Neurosciences, Oxford Autoimmune Neurology Group, University of Oxford, Oxford, UK
| | - Sarosh R Irani
- Nuffield Department of Clinical Neurosciences, Oxford Autoimmune Neurology Group, University of Oxford, Oxford, UK
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Hidenori Matsuo
- Department of Neurology, Nagasaki Kawatana Medical Center, Nagasaki, Japan
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Cao M, Koneczny I, Vincent A. Myasthenia Gravis With Antibodies Against Muscle Specific Kinase: An Update on Clinical Features, Pathophysiology and Treatment. Front Mol Neurosci 2020; 13:159. [PMID: 32982689 PMCID: PMC7492727 DOI: 10.3389/fnmol.2020.00159] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 08/03/2020] [Indexed: 12/24/2022] Open
Abstract
Muscle Specific Kinase myasthenia gravis (MuSK-MG) is an autoimmune disease that impairs neuromuscular transmission leading to generalized muscle weakness. Compared to the more common myasthenia gravis with antibodies against the acetylcholine receptor (AChR), MuSK-MG affects mainly the bulbar and respiratory muscles, with more frequent and severe myasthenic crises. Treatments are usually less effective with the need for prolonged, high doses of steroids and other immunosuppressants to control symptoms. Under physiological condition, MuSK regulates a phosphorylation cascade which is fundamental for the development and maintenance of postsynaptic AChR clusters at the neuromuscular junction (NMJ). Agrin, secreted by the motor nerve terminal into the synaptic cleft, binds to low density lipoprotein receptor-related protein 4 (LRP4) which activates MuSK. In MuSK-MG, monovalent MuSK-IgG4 autoantibodies block MuSK-LRP4 interaction preventing MuSK activation and leading to the dispersal of AChR clusters. Lower levels of divalent MuSK IgG1, 2, and 3 antibody subclasses are also present but their contribution to the pathogenesis of the disease remains controversial. This review aims to provide a detailed update on the epidemiological and clinical features of MuSK-MG, focusing on the pathophysiological mechanisms and the latest indications regarding the efficacy and safety of different treatment options.
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Affiliation(s)
- Michelangelo Cao
- Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Inga Koneczny
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
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O'Connell K, Ramdas S, Palace J. Management of Juvenile Myasthenia Gravis. Front Neurol 2020; 11:743. [PMID: 32793107 PMCID: PMC7393473 DOI: 10.3389/fneur.2020.00743] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/16/2020] [Indexed: 02/06/2023] Open
Abstract
Juvenile Myasthenia Gravis (JMG) is a rare disorder, defined as myasthenia gravis in children younger than 18 years of age. While clinical phenotypes are similar to adults, there are a number of caveats that influence management: broader differential diagnoses; higher rates of spontaneous remission; and the need to initiate appropriate treatment early, to avoid the long-term physical and psychosocial morbidity. Current practice is taken from treatment guidelines for adult MG or individual experience, with considerable variability seen across centers. We discuss our approach to treating JMG, in a large specialist JMG service, and review currently available evidence and highlight potential areas for future research. First-line treatment of generalized JMG is symptomatic management with pyridostigmine, but early use of immunosuppression, where good control is not achieved is important. Oral prednisolone is used as first-line immunosuppression with appropriate prevention and monitoring of side effects. Second-line therapies including azathioprine and mycophenolate may be considered where there is: no response to steroids, inability to wean to a reasonable minimum effective dose or if side-effects are intolerable. Management of ocular JMG is similar, but requires close involvement of ophthalmology in young children to prevent amblyopia. Muscle-specific tyrosine kinase (MuSK)-JMG show a poorer response to pyridostigmine and anecdotal evidence suggests that rituximab should be considered as second-line immunosuppression. Thymectomy is indicated in any patient with a thymoma, and consideration should be given in acetylcholine receptor (AChR) positive JMG allowing time for spontaneous remission. The benefit is less clear in ocular JMG and is not advised in MuSK-JMG. Children experiencing a myasthenic crisis require urgent hospital admission with access to the intensive care unit. PLEX is preferred over IVIG due to rapid onset of action, but this needs to be balanced with feasibility in very young children. Key questions remain in the management of JMG: when to initiate both first- and second-line treatments, choosing between steroid-sparing agents, and determining the optimal dose and treatment duration. We feel that given the rarity of this disease, the establishment of national registries and collaboration across groups will be needed to address these issues and facilitate future drug trials in JMG.
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Affiliation(s)
- Karen O'Connell
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Sithara Ramdas
- Department of Paediatric Neurology, John Radcliffe Hospital, Oxford, United Kingdom
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
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Rodolico C, Bonanno C, Toscano A, Vita G. MuSK-Associated Myasthenia Gravis: Clinical Features and Management. Front Neurol 2020; 11:660. [PMID: 32793097 PMCID: PMC7390870 DOI: 10.3389/fneur.2020.00660] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/02/2020] [Indexed: 01/04/2023] Open
Abstract
Muscle-specific tyrosine kinase (MuSK) myasthenia gravis (MG) is a rare, frequently more severe, subtype of MG with different pathogenesis, and peculiar clinical features. The prevalence varies among countries and ethnic groups, affecting 5–8% of all MG patients. MuSK-MG usually has an acute onset affecting mainly the facial-bulbar muscles. The symptoms usually progress rapidly, within a few weeks. Early respiratory crises are frequent. The disease may lead to generalized muscle weakness up to muscle atrophy. The main bulbar involvement, the absence of significant thymus alterations, and the association with HLA class II DR14, DR16, and DQ5 alleles have been confirmed. Atypical onset, such as ocular involvement, lack of symptom fluctuations, acetylcholinesterase inhibitors failure, and negative results of electrophysiologic testing, if not specifically performed in the mainly involved muscle groups, makes MuSK-MG diagnosis challenging. In most cases, steroids are effective. Conventional immunosuppressants are not commonly able to replace steroids in maintaining a satisfactory long-term control of symptoms. However, the majority of MuSK-MG patients are refractory to treatment. In these cases, the use of rituximab showed promising results, resulting in sustained symptom control.
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Affiliation(s)
- Carmelo Rodolico
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Carmen Bonanno
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Antonio Toscano
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Giuseppe Vita
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
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Takamori M. Myasthenia Gravis: From the Viewpoint of Pathogenicity Focusing on Acetylcholine Receptor Clustering, Trans-Synaptic Homeostasis and Synaptic Stability. Front Mol Neurosci 2020; 13:86. [PMID: 32547365 PMCID: PMC7272578 DOI: 10.3389/fnmol.2020.00086] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 04/28/2020] [Indexed: 12/18/2022] Open
Abstract
Myasthenia gravis (MG) is a disease of the postsynaptic neuromuscular junction (NMJ) where nicotinic acetylcholine (ACh) receptors (AChRs) are targeted by autoantibodies. Search for other pathogenic antigens has detected the antibodies against muscle-specific tyrosine kinase (MuSK) and low-density lipoprotein-related protein 4 (Lrp4), both causing pre- and post-synaptic impairments. Agrin is also suspected as a fourth pathogen. In a complex NMJ organization centering on MuSK: (1) the Wnt non-canonical pathway through the Wnt-Lrp4-MuSK cysteine-rich domain (CRD)-Dishevelled (Dvl, scaffold protein) signaling acts to form AChR prepatterning with axonal guidance; (2) the neural agrin-Lrp4-MuSK (Ig1/2 domains) signaling acts to form rapsyn-anchored AChR clusters at the innervated stage of muscle; (3) adaptor protein Dok-7 acts on MuSK activation for AChR clustering from “inside” and also on cytoskeleton to stabilize AChR clusters by the downstream effector Sorbs1/2; (4) the trans-synaptic retrograde signaling contributes to the presynaptic organization via: (i) Wnt-MuSK CRD-Dvl-β catenin-Slit 2 pathway; (ii) Lrp4; and (iii) laminins. The presynaptic Ca2+ homeostasis conditioning ACh release is modified by autoreceptors such as M1-type muscarinic AChR and A2A adenosine receptors. The post-synaptic structure is stabilized by: (i) laminin-network including the muscle-derived agrin; (ii) the extracellular matrix proteins (including collagen Q/perlecan and biglycan which link to MuSK Ig1 domain and CRD); and (iii) the dystrophin-associated glycoprotein complex. The study on MuSK ectodomains (Ig1/2 domains and CRD) recognized by antibodies suggested that the MuSK antibodies were pathologically heterogeneous due to their binding to multiple functional domains. Focussing one of the matrix proteins, biglycan which functions in the manner similar to collagen Q, our antibody assay showed the negative result in MG patients. However, the synaptic stability may be impaired by antibodies against MuSK ectodomains because of the linkage of biglycan with MuSK Ig1 domain and CRD. The pathogenic diversity of MG is discussed based on NMJ signaling molecules.
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Di Stefano V, Lupica A, Rispoli MG, Di Muzio A, Brighina F, Rodolico C. Rituximab in AChR subtype of myasthenia gravis: systematic review. J Neurol Neurosurg Psychiatry 2020; 91:392-395. [PMID: 32098874 DOI: 10.1136/jnnp-2019-322606] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/04/2020] [Accepted: 02/05/2020] [Indexed: 11/03/2022]
Abstract
Myasthenia gravis (MG) is a chronic autoimmune disorder of the neuromuscular junction characterised by an autoantibody against acetylcholine receptor (AChR-Ab), autoantibody against muscle-specific kinase (MuSK-Ab), lipoprotein-related protein 4 or agrin in the postsynaptic membrane at the neuromuscular junction. Many patients are resistant to conventional treatment and effective therapies are needed. Rituximab (RTX) is a monoclonal antibody directed against CD20 antigen on B cells which has been successfully employed in anti-MuSK-Ab+MG, but the efficacy in anti-AChR-Ab+MG is still debated. The purpose of this systematic review was to describe the best evidence for RTX in the acetylcholine receptor subtype. The authors undertook a literature search during the period of 1999-2019 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analys methodology, employing (myasthenia)+(gravis)+(RTX) as search terms. The analysis was confined to studies that include at least five patients with confirmed anti-AChR-Ab+MG. Thirteen studies have been selected, showing a good safety. The data obtained were heterogeneous in terms of posology, administration scheme and patients' evaluation, ranging from a minimum of two to a maximum of three cycles. RTX led to a sustained clinical improvement with prolonged time to relapse, in parallel to a reduction or discontinuation of other immunosuppressive therapies. Treatment with RTX appears to work in some but not all patients with anti-AChR-Ab+MG, but randomised controlled trials are needed. Future studies should take into account the subtype of MG and employ reliable measures of outcome and severity focusing on how to identify patients who may benefit from the treatment. Trial registration number: NCT02110706.
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Affiliation(s)
- Vincenzo Di Stefano
- Department of Biomedicine, Neuroscience and advanced Diagnostic, University of Palermo, Palermo, Sicily, Italy .,Department of Neuroscience Imaging and Clinical Sciences, Gabriele d'Annunzio University of Chieti and Pescara, Chieti, Abruzzo, Italy
| | - Antonino Lupica
- Department of Clinical and Experimental Medicine, Unit of Neurology and Neuromuscular Disease, University of Messina, Messina, Sicilia, Italy
| | - Marianna Gabriella Rispoli
- Department of Neuroscience Imaging and Clinical Sciences, Gabriele d'Annunzio University of Chieti and Pescara, Chieti, Abruzzo, Italy
| | - Antonio Di Muzio
- Department of Neurology, SS Annunziata Hospital, Chieti, Abruzzo, Italy
| | - Filippo Brighina
- Department of Biomedicine, Neuroscience and advanced Diagnostic, University of Palermo, Palermo, Sicily, Italy
| | - Carmelo Rodolico
- Department of Clinical and Experimental Medicine, Unit of Neurology and Neuromuscular Disease, University of Messina, Messina, Sicilia, Italy
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Gastaldi M, Zardini E, Scaranzin S, Uccelli A, Andreetta F, Baggi F, Franciotta D. Autoantibody Diagnostics in Neuroimmunology: Experience From the 2018 Italian Neuroimmunology Association External Quality Assessment Program. Front Neurol 2020; 10:1385. [PMID: 32010046 PMCID: PMC6971200 DOI: 10.3389/fneur.2019.01385] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 12/16/2019] [Indexed: 12/31/2022] Open
Abstract
Background: Neuroimmunology has impressively expanded in the past decade. Novel assays, especially cell-based assays (CBAs) can detect conformational antibodies (Abs) recognizing antigens in their native conformation. Generally, the availability of in-house and of commercial tests has improved the diagnostics, but introduced demanding laboratory tasks. Hence, standardization and quality controls represent a key step to promote accuracy. We report on the results of the 2018 external quality assessment program (EQAP) organized by the Italian Neuroimmunology Association. Methods: EQAP regarded 10 schemes, including oligoclonal bands (OCBs), intracellular-neuronal (ICN)-Abs, neuronal-surface (NS)-Abs, aquaporin-4 (AQP4)-Abs, myelin oligodendrocyte glycoprotein (MOG)-Abs, myelin-associated glycoprotein (MAG)-Abs, ganglioside-Abs, acetylcholine-receptor (AChR)-Abs, and muscle-specific-kinase (MuSK)-Abs, and 34 laboratories. Assays were classified as tissue-based assays (TBAs), solid-phase assays (SPAs), liquid-phase assays (LPAs), and CBAs. Thirty-three samples were provided. Results: Three-quarter of the tests were commercial. Median accuracy for the laboratories was 75% (range 50–100). In 8/10 schemes, at least one sample provided discrepant results. Inter-laboratory “substantial agreement” was found in 6/10 schemes (AChR, MuSK, MAG, AQP4, MOG, and NS-Abs), whereas the worst agreements regarded OCBs and ganglioside-Abs. Both commercial and in-house assays performed better in experienced laboratories. Conclusions: Assays could be divided in (a) robust commercial tests with substantial inter-laboratory agreement (MAG-Abs; AChR- and MuSK-Abs); commercial/“in-house” tests with (b) partial inter-laboratory agreement (AQP4-Abs, MOG-Abs, NS-Abs, ICN-Abs), and (c) with large inter-laboratory disagreement (OCBs, ganglioside-Abs). This real-life snapshot of the neuroimmunology test performances highlights shortcomings attributable to technician-dependent performances, assay structural limitations, and errors in test interpretations.
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Affiliation(s)
- Matteo Gastaldi
- Neuroimmunology Laboratory, IRCCS Mondino Foundation, Pavia, Italy
| | - Elisabetta Zardini
- Neuroimmunology Laboratory, IRCCS Mondino Foundation, Pavia, Italy.,Department of Brain and Behavioral Science, University of Pavia, Pavia, Italy
| | - Silvia Scaranzin
- Neuroimmunology Laboratory, IRCCS Mondino Foundation, Pavia, Italy
| | - Antonio Uccelli
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, Genoa, Italy.,Ospedale Policlinico San Martino - IRCCS, Genoa, Italy
| | - Francesca Andreetta
- UO Neurology IV, IRCCS Fondazione Istituto Neurologico Carlo Besta, Milan, Italy
| | - Fulvio Baggi
- UO Neurology IV, IRCCS Fondazione Istituto Neurologico Carlo Besta, Milan, Italy
| | - Diego Franciotta
- Neuroimmunology Laboratory, IRCCS Mondino Foundation, Pavia, Italy
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Huda S, Cao M, De Rosa A, Woodhall M, Rodriguez Cruz PM, Cossins J, Maestri M, Ricciardi R, Evoli A, Beeson D, Vincent A. SHP2 inhibitor protects AChRs from effects of myasthenia gravis MuSK antibody. NEUROLOGY-NEUROIMMUNOLOGY & NEUROINFLAMMATION 2019; 7:7/1/e645. [PMID: 31831571 PMCID: PMC6935836 DOI: 10.1212/nxi.0000000000000645] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 10/08/2019] [Indexed: 11/30/2022]
Abstract
Objective To determine whether an SRC homology 2 domain-containing phosphotyrosine phosphatase 2 (SHP2) inhibitor would increase muscle-specific kinase (MuSK) phosphorylation and override the inhibitory effect of MuSK-antibodies (Abs). Methods The effect of the SHP2 inhibitor NSC-87877 on MuSK phosphorylation and AChR clustering was tested in C2C12 myotubes with 31 MuSK-myasthenia gravis (MG) sera and purified MuSK-MG IgG4 preparations. Results In the absence of MuSK-MG Abs, NSC-87877 increased MuSK phosphorylation and the number of AChR clusters in C2C12 myotubes in vitro and in DOK7-overexpressing C2C12 myotubes that form spontaneous AChR clusters. In the presence of MuSK-MG sera, the AChR clusters were reduced, as expected, but NSC-87877 was able to protect or restore the clusters. Two purified MuSK-MG IgG4 preparations inhibited both MuSK phosphorylation and AChR cluster formation, and in both, clusters were restored with NSC-87877. Conclusions Stimulating the agrin-LRP4-MuSK-DOK7 AChR clustering pathway with NSC-87877, or other drugs, could represent a novel therapeutic approach for MuSK-MG and could potentially improve other NMJ disorders with reduced AChR numbers or disrupted NMJs.
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Affiliation(s)
- Saif Huda
- From the Department of Clinical Neurosciences (S.H., M.C., M.W., P.M.R.C., J.C., D.B., A.V.), Weatherall Institute of Molecular Medicine and Nuffield, University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy
| | - Michelangelo Cao
- From the Department of Clinical Neurosciences (S.H., M.C., M.W., P.M.R.C., J.C., D.B., A.V.), Weatherall Institute of Molecular Medicine and Nuffield, University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy
| | - Anna De Rosa
- From the Department of Clinical Neurosciences (S.H., M.C., M.W., P.M.R.C., J.C., D.B., A.V.), Weatherall Institute of Molecular Medicine and Nuffield, University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy
| | - Mark Woodhall
- From the Department of Clinical Neurosciences (S.H., M.C., M.W., P.M.R.C., J.C., D.B., A.V.), Weatherall Institute of Molecular Medicine and Nuffield, University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy
| | - Pedro M Rodriguez Cruz
- From the Department of Clinical Neurosciences (S.H., M.C., M.W., P.M.R.C., J.C., D.B., A.V.), Weatherall Institute of Molecular Medicine and Nuffield, University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy
| | - Judith Cossins
- From the Department of Clinical Neurosciences (S.H., M.C., M.W., P.M.R.C., J.C., D.B., A.V.), Weatherall Institute of Molecular Medicine and Nuffield, University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy
| | - Michelangelo Maestri
- From the Department of Clinical Neurosciences (S.H., M.C., M.W., P.M.R.C., J.C., D.B., A.V.), Weatherall Institute of Molecular Medicine and Nuffield, University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy
| | - Roberta Ricciardi
- From the Department of Clinical Neurosciences (S.H., M.C., M.W., P.M.R.C., J.C., D.B., A.V.), Weatherall Institute of Molecular Medicine and Nuffield, University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy
| | - Amelia Evoli
- From the Department of Clinical Neurosciences (S.H., M.C., M.W., P.M.R.C., J.C., D.B., A.V.), Weatherall Institute of Molecular Medicine and Nuffield, University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy
| | - David Beeson
- From the Department of Clinical Neurosciences (S.H., M.C., M.W., P.M.R.C., J.C., D.B., A.V.), Weatherall Institute of Molecular Medicine and Nuffield, University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy
| | - Angela Vincent
- From the Department of Clinical Neurosciences (S.H., M.C., M.W., P.M.R.C., J.C., D.B., A.V.), Weatherall Institute of Molecular Medicine and Nuffield, University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy.
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A novel MuSK cell-based myasthenia gravis diagnostic assay. J Neuroimmunol 2019; 337:577076. [PMID: 31655425 DOI: 10.1016/j.jneuroim.2019.577076] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 09/19/2019] [Accepted: 09/27/2019] [Indexed: 10/25/2022]
Abstract
To improve the clinical diagnosis of neural autoimmune diseases, we developed an in-house muscle-specific kinase (MuSK) antibody cell-based assay (CBA) and compared its performance with RIA, ELISA, and other CBAs. Sera from patients with myasthenia gravis (MG) and other autoimmune diseases were analyzed. We found 46 (18.3%) MuSK-CBA Ab positive cases among 251 AChR-Ab negative cases [patients] and 4 (0.6%) MuSK-CBA Ab positive cases [among] the 624 AChR-Ab positive samples. Comparing these with available clinic assays, our highly specific CBA method is more sensitive than commercial ELISA and IFA(indirect immunofluorescence assay).
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34
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Myasthenia Gravis: Pathogenic Effects of Autoantibodies on Neuromuscular Architecture. Cells 2019; 8:cells8070671. [PMID: 31269763 PMCID: PMC6678492 DOI: 10.3390/cells8070671] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 06/26/2019] [Accepted: 06/28/2019] [Indexed: 12/13/2022] Open
Abstract
Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction (NMJ). Autoantibodies target key molecules at the NMJ, such as the nicotinic acetylcholine receptor (AChR), muscle-specific kinase (MuSK), and low-density lipoprotein receptor-related protein 4 (Lrp4), that lead by a range of different pathogenic mechanisms to altered tissue architecture and reduced densities or functionality of AChRs, reduced neuromuscular transmission, and therefore a severe fatigable skeletal muscle weakness. In this review, we give an overview of the history and clinical aspects of MG, with a focus on the structure and function of myasthenic autoantigens at the NMJ and how they are affected by the autoantibodies' pathogenic mechanisms. Furthermore, we give a short overview of the cells that are implicated in the production of the autoantibodies and briefly discuss diagnostic challenges and treatment strategies.
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35
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Takata K, Stathopoulos P, Cao M, Mané-Damas M, Fichtner ML, Benotti ES, Jacobson L, Waters P, Irani SR, Martinez-Martinez P, Beeson D, Losen M, Vincent A, Nowak RJ, O'Connor KC. Characterization of pathogenic monoclonal autoantibodies derived from muscle-specific kinase myasthenia gravis patients. JCI Insight 2019; 4:127167. [PMID: 31217355 PMCID: PMC6629167 DOI: 10.1172/jci.insight.127167] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 05/10/2019] [Indexed: 12/15/2022] Open
Abstract
Myasthenia gravis (MG) is a chronic autoimmune disorder characterized by muscle weakness and caused by pathogenic autoantibodies that bind to membrane proteins at the neuromuscular junction. Most patients have autoantibodies against the acetylcholine receptor (AChR), but a subset of patients have autoantibodies against muscle-specific tyrosine kinase (MuSK) instead. MuSK is an essential component of the pathway responsible for synaptic differentiation, which is activated by nerve-released agrin. Through binding MuSK, serum-derived autoantibodies inhibit agrin-induced MuSK autophosphorylation, impair clustering of AChRs, and block neuromuscular transmission. We sought to establish individual MuSK autoantibody clones so that the autoimmune mechanisms could be better understood. We isolated MuSK autoantibody-expressing B cells from 6 MuSK MG patients using a fluorescently tagged MuSK antigen multimer, then generated a panel of human monoclonal autoantibodies (mAbs) from these cells. Here we focused on 3 highly specific mAbs that bound quantitatively to MuSK in solution, to MuSK-expressing HEK cells, and at mouse neuromuscular junctions, where they colocalized with AChRs. These 3 IgG isotype mAbs (2 IgG4 and 1 IgG3 subclass) recognized the Ig-like domain 2 of MuSK. The mAbs inhibited AChR clustering, but intriguingly, they enhanced rather than inhibited MuSK phosphorylation, which suggests an alternative mechanism for inhibiting AChR clustering. A fluorescent tetrameric antigen allows isolation of human myasthenia gravis monoclonal antibodies that interrupt acetylcholine receptor signaling.
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Affiliation(s)
- Kazushiro Takata
- Department of Neurology and.,Department of Immunobiology, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Panos Stathopoulos
- Department of Neurology and.,Department of Immunobiology, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Michelangelo Cao
- Neurosciences Group, Weatherall Institute of Molecular Medicine and Nuffield Department of Clinical Neurosciences, Oxford, England
| | - Marina Mané-Damas
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, Netherlands
| | - Miriam L Fichtner
- Department of Neurology and.,Department of Immunobiology, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Erik S Benotti
- Department of Neurology and.,Department of Immunobiology, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Leslie Jacobson
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, England
| | - Patrick Waters
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, England
| | - Sarosh R Irani
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, England
| | - Pilar Martinez-Martinez
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, Netherlands
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine and Nuffield Department of Clinical Neurosciences, Oxford, England
| | - Mario Losen
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, Netherlands
| | - Angela Vincent
- Neurosciences Group, Weatherall Institute of Molecular Medicine and Nuffield Department of Clinical Neurosciences, Oxford, England
| | | | - Kevin C O'Connor
- Department of Neurology and.,Department of Immunobiology, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
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Li M, Han J, Zhang Y, Lv J, Zhang J, Zhao X, Ren L, Fang H, Yang J, Zhang Y, Cui X, Zhang Q, Li Q, Du Y, Gao F. Clinical analysis of Chinese anti-low-density-lipoprotein-receptor-associated protein 4 antibodies in patients with myasthenia gravis. Eur J Neurol 2019; 26:1296-e84. [PMID: 31050101 DOI: 10.1111/ene.13979] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 04/23/2019] [Indexed: 01/17/2023]
Abstract
BACKGROUND AND PURPOSE Low-density-lipoprotein-receptor-associated protein 4 (LRP4) autoantibodies have recently been detected in myasthenia gravis (MG), but little is known about the clinical characteristics associated with this serological type. In this study, the clinical features of Chinese patients with anti-LRP4 antibody-positive MG were characterized. METHODS A total of 2172 MG serum samples were collected from patients in various parts of China. An enzyme-linked immunosorbent assay was used to detect acetylcholine receptor (AChR) antibody and titin antibody, and cell-based assays were used to detect muscle-specific kinase antibody and LRP4 antibody. Clinical data for patients with MG were collected from different provinces in China. RESULTS In total, 16 (0.8%) patients with LRP4-MG were found amongst 2172 total patients, including three patients with AChR/LRP4-MG. Additionally, 13 (2.9%) patients with LRP4-MG were found amongst 455 patients with double seronegative MG. The ratio of males to females for these 13 patients was 1:1.6, and 53.8% patients were children. A total of 91.7% of cases exhibited initial ocular involvement, and 58.3% of cases exhibited simple eye muscle involvement. Responses to acetylcholinesterase inhibitors and prednisone were observed. CONCLUSION The expanded sample confirmed that the positive rate of LRP4 antibodies in China is lower than that in western countries. Our results highlighted the differences between LRP4-MG and other antibody groups. Children and female patients with LRP4-MG have a higher prevalence, often involving the ocular muscles and limb muscles. The clinical symptoms are mild, and satisfactory responses to treatment are often achieved.
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Affiliation(s)
- M Li
- Department of Neurology, Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - J Han
- Department of Neuroimmunology, Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
| | - Y Zhang
- Department of Neuroimmunology, Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
| | - J Lv
- Department of Neuroimmunology, Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
| | - J Zhang
- Department of Neuroimmunology, Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
| | - X Zhao
- Department of Neuroimmunology, Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
| | - L Ren
- Department of Neurology, Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - H Fang
- Department of Neuroimmunology, Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
| | - J Yang
- Department of Encephalopathy, First Affiliated Hospital of Henan University of TCM, Zhengzhou, China
| | - Y Zhang
- Department of Encephalopathy, First Affiliated Hospital of Henan University of TCM, Zhengzhou, China
| | - X Cui
- Myasthenia Gravis Comprehensive Diagnosis and Treatment Center, Henan Provincial People's Hospital, Zhengzhou, China
| | - Q Zhang
- Myasthenia Gravis Comprehensive Diagnosis and Treatment Center, Henan Provincial People's Hospital, Zhengzhou, China
| | - Q Li
- Department of Immunology and Microbiology, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Y Du
- Department of Immunology and Microbiology, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - F Gao
- Department of Neuroimmunology, Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
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Abstract
Myasthenia gravis (MG) is an autoimmune disease caused by antibodies against the acetylcholine receptor (AChR), muscle-specific kinase (MuSK) or other AChR-related proteins in the postsynaptic muscle membrane. Localized or general muscle weakness is the predominant symptom and is induced by the antibodies. Patients are grouped according to the presence of antibodies, symptoms, age at onset and thymus pathology. Diagnosis is straightforward in most patients with typical symptoms and a positive antibody test, although a detailed clinical and neurophysiological examination is important in antibody-negative patients. MG therapy should be ambitious and aim for clinical remission or only mild symptoms with near-normal function and quality of life. Treatment should be based on MG subgroup and includes symptomatic treatment using acetylcholinesterase inhibitors, thymectomy and immunotherapy. Intravenous immunoglobulin and plasma exchange are fast-acting treatments used for disease exacerbations, and intensive care is necessary during exacerbations with respiratory failure. Comorbidity is frequent, particularly in elderly patients. Active physical training should be encouraged.
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Abstract
PURPOSE OF REVIEW The current article reviews the recent advances in the field of myasthenia gravis, which span from autoantibody profiling and pathogenic mechanisms to therapy innovation. The overview is highlighting specifically the data and the needs of targeted treatments in the light of precision medicine in myasthenia gravis. RECENT FINDINGS Novel data published recently further increased our knowledge on myasthenia gravis. The use of cell-based assays has greatly improved autoantibody detection in myasthenia gravis patients, and the mechanisms of action of these antibodies have been described. The role of Toll-like receptor activation in the generation of thymic alterations and anti-acetylcholine receptor autosensitization has been further investigated implementing our understanding on the relationships between innate immunity and autoimmunity. Additional studies have been focused on the alterations of T-cell/B-cell regulatory mechanisms in thymus and peripheral blood of myasthenia gravis patients. microRNAs and genetic factors are also emerging as key biomarkers in myasthenia gravis pathogenesis and prediction of drug efficacy in individual patients. SUMMARY The recent immunological and pathological findings in myasthenia gravis promise to improve myasthenia gravis treatment, via the development of more precise and personalized therapies.
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Italian recommendations for the diagnosis and treatment of myasthenia gravis. Neurol Sci 2019; 40:1111-1124. [PMID: 30778878 DOI: 10.1007/s10072-019-03746-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 01/31/2019] [Indexed: 12/30/2022]
Abstract
Myasthenia gravis is a well-treatable disease, in which a prompt diagnosis and an adequate management can achieve satisfactory control of symptoms in the great majority of patients. Improved knowledge of the disease pathogenesis has led to recognition of patient subgroups, according to associated antibodies, age at onset and thymus pathology, and to a more personalized treatment. When myasthenia gravis is suspected on clinical grounds, diagnostic confirmation relies mainly on the detection of specific antibodies. Neurophysiological studies and, to a lesser extent, clinical response to cholinesterase inhibitors support the diagnosis in seronegative patients. In these cases, the differentiation from congenital myasthenia can be challenging. Treatment planning must consider weakness extension and severity, disease subtype, thymus pathology, together with patient characteristics and comorbidities. Since most subjects with myasthenia gravis require long-term immunosuppressive therapy, surveillance of expected and potential adverse events is critical. For patients refractory to conventional immunosuppression, the use of biologic agents is highly promising. These recommendations are addressed to non-experts on neuromuscular transmission disorders. The diagnostic procedures and therapeutic approaches hereafter described are largely accessible in Italy.
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Cortés-Vicente E, Rojas-Garcia R, Díaz-Manera J, Querol L, Casasnovas C, Guerrero-Sola A, Muñoz-Blanco JL, Bárcena-Llona JE, Márquez-Infante C, Pardo J, Martínez-Fernández EM, Usón M, Oliva-Nacarino P, Sevilla T, Illa I. The impact of rituximab infusion protocol on the long-term outcome in anti-MuSK myasthenia gravis. Ann Clin Transl Neurol 2018; 5:710-716. [PMID: 29928654 PMCID: PMC5989782 DOI: 10.1002/acn3.564] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 03/07/2018] [Accepted: 03/20/2018] [Indexed: 01/11/2023] Open
Abstract
Objective To evaluate whether the clinical benefit and relapse rates in anti‐muscle‐specific kinase (MuSK) myasthenia gravis (MG) differ depending on the protocol of rituximab followed. Methods This retrospective multicentre study in patients with MuSK MG compared three rituximab protocols in terms of clinical status, relapse, changes in treatment, and adverse side effects. The primary effectiveness endpoint was clinical relapse requiring a further infusion of rituximab. Survival curves were estimated using Kaplan–Meier methods and survival analyses were undertaken using Cox proportional‐hazards models. Results Twenty‐five patients were included: 11 treated with protocol 4 + 2 (375 mg/m2/4 weeks, then monthly for 2 months), five treated with protocol 1 + 1 (two 1 g doses 2 weeks apart), and nine treated with protocol 4 (375 mg/m2/4 weeks). Mean follow‐up was 5.0 years (SD 3.3). Relapse occurred in 18.2%, 80%, and 33.3%, and mean time to relapse was 3.5 (SD 1.5), 1.1 (SD 0.4), and 2.5 (SD 1.4) years, respectively. Based on Kaplan–Meier estimates, patients treated with protocol 4 + 2 had fewer and later relapses than patients treated with the other two protocols (log‐rank test P = 0.0001). Patients treated with protocol 1 + 1 had a higher risk of relapse than patients treated with protocol 4 + 2 (HR 112.8, 95% CI, 5.7–2250.4, P = 0.002). Patients treated with protocol 4 showed a trend to a higher risk of relapse than those treated with protocol 4 + 2 (HR 9.2, 95% CI 0.9–91.8, P = 0.059). Interpretation This study provides class IV evidence that the 4 + 2 rituximab protocol has a lower clinical relapse rate and produces a more durable response than the 1 + 1 and 4 protocols in patients with MuSK MG.
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Affiliation(s)
- Elena Cortés-Vicente
- Neuromuscular Diseases Unit Department of Neurology Hospital de la Santa Creu i Sant Pau Universitat Autònoma de Barcelona Barcelona Spain.,Centre for Biomedical Network Research on Rare Diseases (CIBERER) Madrid Spain
| | - Ricard Rojas-Garcia
- Neuromuscular Diseases Unit Department of Neurology Hospital de la Santa Creu i Sant Pau Universitat Autònoma de Barcelona Barcelona Spain.,Centre for Biomedical Network Research on Rare Diseases (CIBERER) Madrid Spain
| | - Jordi Díaz-Manera
- Neuromuscular Diseases Unit Department of Neurology Hospital de la Santa Creu i Sant Pau Universitat Autònoma de Barcelona Barcelona Spain.,Centre for Biomedical Network Research on Rare Diseases (CIBERER) Madrid Spain
| | - Luis Querol
- Neuromuscular Diseases Unit Department of Neurology Hospital de la Santa Creu i Sant Pau Universitat Autònoma de Barcelona Barcelona Spain.,Centre for Biomedical Network Research on Rare Diseases (CIBERER) Madrid Spain
| | - Carlos Casasnovas
- Neuromuscular Diseases Unit Department of Neurology Hospital Universitari de Bellvitge - IDIBELL L'Hospitalet de Llobregat Barcelona Spain
| | - Antonio Guerrero-Sola
- Neuromuscular Diseases Unit Department of Neurology Hospital Universitario Clínico San Carlos Madrid Spain
| | - José Luis Muñoz-Blanco
- ALS-Neuromuscular Unit Department of Neurology Hospital General Universitario Gregorio Marañón IISGM Madrid Spain
| | | | - Celedonio Márquez-Infante
- Neuromuscular Diseases Unit Department of Neurology and Neurophysiology Hospital Universitario Virgen del Rocío Sevilla Spain
| | - Julio Pardo
- Department of Neurology Hospital Clínico Santiago de Compostela Spain
| | | | - Mercedes Usón
- Department of Neurology Hospital Son Llàtzer Palma de Mallorca Spain
| | | | - Teresa Sevilla
- Centre for Biomedical Network Research on Rare Diseases (CIBERER) Madrid Spain.,Neuromuscular Unit Department of Neurology Hospital Universitari i Politècnic La Fe Valencia Spain.,Department of Medicine University of Valencia Valencia Spain
| | - Isabel Illa
- Neuromuscular Diseases Unit Department of Neurology Hospital de la Santa Creu i Sant Pau Universitat Autònoma de Barcelona Barcelona Spain.,Centre for Biomedical Network Research on Rare Diseases (CIBERER) Madrid Spain
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41
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Morren J, Li Y. Myasthenia gravis with muscle-specific tyrosine kinase antibodies: A narrative review. Muscle Nerve 2018; 58:344-358. [DOI: 10.1002/mus.26107] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 02/09/2018] [Accepted: 02/18/2018] [Indexed: 12/14/2022]
Affiliation(s)
- John Morren
- Neuromuscular Center, Neurological Institute, Cleveland Clinic, 9500 Euclid Avenue, Desk S90; Cleveland Ohio 44195 USA
| | - Yuebing Li
- Neuromuscular Center, Neurological Institute, Cleveland Clinic, 9500 Euclid Avenue, Desk S90; Cleveland Ohio 44195 USA
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42
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Park KH, Waters P, Woodhall M, Lang B, Smith T, Sung JJ, Kim KK, Lim YM, Kim JE, Kim BJ, Park JS, Lim JG, Kim DS, Kwon O, Sohn EH, Bae JS, Yoon BN, Kim NH, Ahn SW, Oh J, Park HJ, Shin KJ, Hong YH. Myasthenia gravis seronegative for acetylcholine receptor antibodies in South Korea: Autoantibody profiles and clinical features. PLoS One 2018. [PMID: 29518096 PMCID: PMC5843234 DOI: 10.1371/journal.pone.0193723] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Acquired myasthenia gravis (MG) is a prototype autoimmune disease of the neuromuscular junction, caused in most patients by autoantibodies to the muscle nicotinic acetylcholine receptor (AChR). There seem to be ethnic and regional differences in the frequency and clinical features of MG seronegative for the AChR antibody. This study aimed to describe the autoantibody profiles and clinical features of Korean patients with generalized MG seronegative for the AChR antibody. A total of 62 patients with a high index of clinical suspicion of seronegative generalized MG were identified from 18 centers, and we examined their sera for antibodies to clustered AChR, muscle-specific tyrosine kinase (MuSK), and low-density lipoprotein receptor-related protein 4 (LRP4) by cell-based assays (CBA) and to MuSK by radioimmunoprecipitation assay (RIPA). We also included 8 patients with ocular MG, 3 with Lambert-Eaton myasthenic syndrome, 5 with motor neuron disease, and 9 with other diagnoses as comparators for the serological testing. Antibodies were identified in 25/62 (40.3%) patients: 7 had antibodies to clustered AChR, 17 to MuSK, and 2 to LRP4. Three patients were double seropositive: 1 for MuSK and LRP4, and 2 for MuSK and clustered AChR. The patients with MuSK antibodies were mostly female (88.2%) and characterized by predominantly bulbar involvement (70%) and frequent myasthenic crises (58.3%). The patients with antibodies to clustered AChR, including 2 with ocular MG, tended to have a mild phenotype and good prognosis.
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Affiliation(s)
- Kee Hong Park
- Department of Neurology, Gyeongsang National University Hospital, Jinju, Republic of Korea
| | - Patrick Waters
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, United Kingdom
- * E-mail: (YHH); (PW)
| | - Mark Woodhall
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Bethan Lang
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Thomas Smith
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, United Kingdom
| | - Jung-Joon Sung
- Department of Neurology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Kwang-Kuk Kim
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Young-Min Lim
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Jee-Eun Kim
- Department of Neurology, Seoul Medical Center, Seoul, Republic of Korea
| | - Byung-Jo Kim
- Department of Neurology, Korea University College of Medicine, Korea University Anam Hospital, Seoul, Republic of Korea
| | - Jin-Sung Park
- Department of Neurology, Kyungpook National University, School of Medicine, Daegu, Republic of Korea
| | - Jeong-Geon Lim
- Department of Neurology, Keimyung University School of Medicine, Daegu, Republic of Korea
| | - Dae-Seong Kim
- Department of Neurology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea
| | - Ohyun Kwon
- Department of Neurology, School of Medicine, Eulji University, Seoul, Republic of Korea
| | - Eun Hee Sohn
- Department of Neurology, Chungnam National University Hospital, Daejeon, Republic of Korea
| | - Jong Seok Bae
- Department of Neurology, College of Medicine, Hallym University, Seoul, Republic of Korea
| | - Byung-Nam Yoon
- Department of Neurology, Inha University Hospital, Incheon, Republic of Korea
| | - Nam-Hee Kim
- Department of Neurology, Dongguk University Ilsan Hospital, Goyangsi, Gyeonggido, Republic of Korea
| | - Suk-Won Ahn
- Department of Neurology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea
| | - Jeeyoung Oh
- Department of Neurology, Konkuk University Medical Center, Seoul, Republic of Korea
| | - Hyung Jun Park
- Department of Neurology, Mokdong Hospital, Ewha Womans University School of Medicine, Seoul, Republic of Korea
| | - Kyong Jin Shin
- Department of Neurology, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Republic of Korea
| | - Yoon-Ho Hong
- Department of Neurology, Seoul National University College of Medicine, Seoul National University Seoul Metropolitan Government Boramae Medical Center, Seoul National University Medical Research Council, Seoul, Republic of Korea
- * E-mail: (YHH); (PW)
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43
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Vincent A, Huda S, Cao M, Cetin H, Koneczny I, Rodriguez Cruz PM, Jacobson L, Viegas S, Jacob S, Woodhall M, Nagaishi A, Maniaol A, Damato V, Leite MI, Cossins J, Webster R, Palace J, Beeson D. Serological and experimental studies in different forms of myasthenia gravis. Ann N Y Acad Sci 2018; 1413:143-153. [PMID: 29377162 DOI: 10.1111/nyas.13592] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 12/11/2017] [Accepted: 12/12/2017] [Indexed: 12/11/2022]
Abstract
Antibodies to the acetylcholine receptor (AChR) have been recognized for over 40 years and have been important in the diagnosis of myasthenia gravis (MG), and its recognition in patients of different ages and thymic pathologies. The 10-20% of patients who do not have AChR antibodies are now known to comprise different subgroups, the most commonly reported of which is patients with antibodies to muscle-specific kinase (MuSK). The use of cell-based assays has extended the repertoire of antibody tests to clustered AChRs, low-density lipoprotein receptor-related protein 4, and agrin. Autoantibodies against intracellular targets, namely cortactin, titin, and ryanodine receptor (the latter two being associated with the presence of thymoma), may also be helpful as biomarkers in some patients. IgG4 MuSK antibodies are clearly pathogenic, but the coexisting IgG1, IgG2, and IgG3 antibodies, collectively, have effects that question the dominance of IgG4 as the sole pathologic factor in MuSK MG. After a brief historical review, we define the different subgroups and summarize the antibody characteristics. Experiments to demonstrate the in vitro and in vivo pathogenic roles of MuSK antibodies are discussed.
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Affiliation(s)
- Angela Vincent
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Saif Huda
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Michelangelo Cao
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Hakan Cetin
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Inga Koneczny
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Pedro M Rodriguez Cruz
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Leslie Jacobson
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Stuart Viegas
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Saiju Jacob
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Mark Woodhall
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Akiko Nagaishi
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Angelina Maniaol
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Valentina Damato
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - M Isabel Leite
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Judith Cossins
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Richard Webster
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Jacqueline Palace
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - David Beeson
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
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44
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Evoli A, Alboini PE, Damato V, Iorio R, Provenzano C, Bartoccioni E, Marino M. Myasthenia gravis with antibodies to MuSK: an update. Ann N Y Acad Sci 2017; 1412:82-89. [PMID: 29266255 DOI: 10.1111/nyas.13518] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 09/06/2017] [Accepted: 09/12/2017] [Indexed: 02/06/2023]
Abstract
Myasthenia gravis with antibodies to the muscle-specific tyrosine kinase (MuSK+ MG) is a rare disease with distinctive pathogenic mechanisms and clinical features. An acute onset and predominant bulbar muscle weakness are very common and highly suggestive of the disease. On the other hand, a more indolent course, atypical ocular presentation, and signs of cholinergic hyperactivity may complicate the diagnosis. Though MuSK+ MG is still a severe disease, over the years we have observed a steady reduction in the rate of respiratory crisis and a significant improvement in the clinical outcome, both likely related to earlier diagnosis and timely treatment. Despite the improved management, MuSK+ MG patients tend to remain dependent on long-term immunosuppressive treatment and may develop permanent disabling weakness. In uncontrolled studies, B cell depletion with rituximab proved effective in most patients with refractory disease, inducing prolonged clinical responses associated with a sustained reduction of serum antibody levels. Promising results from experimental studies and case reports suggest that both 3,4-diaminopyridine and albuterol may be effective as symptomatic agents.
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Affiliation(s)
- Amelia Evoli
- Institute of Neurology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Paolo E Alboini
- Institute of Neurology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Valentina Damato
- Institute of Neurology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Raffaele Iorio
- Institute of Neurology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Carlo Provenzano
- Institute of General Pathology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Emanuela Bartoccioni
- Institute of General Pathology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Mariapaola Marino
- Institute of General Pathology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
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45
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Catar O, Aubé-Nathier AC, Nadaj-Pakleza A. Myasthénie auto-immune séronégative. Med Sci (Paris) 2017; 33 Hors série n°1:34-38. [DOI: 10.1051/medsci/201733s107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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46
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Illa I, Cortés-Vicente E, Martínez MÁ, Gallardo E. Diagnostic utility of cortactin antibodies in myasthenia gravis. Ann N Y Acad Sci 2017; 1412:90-94. [PMID: 29068555 DOI: 10.1111/nyas.13502] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 09/04/2017] [Accepted: 09/07/2017] [Indexed: 12/28/2022]
Abstract
Patients with myasthenia gravis (MG) without antibodies to the acetylcholine receptor (AChR) or muscle-specific tyrosine kinase (MuSK) have been classified as having double-seronegative myasthenia gravis (dSNMG). We used the sera from six dSNMG patients with positive immunohistochemistry assays in a protein array to screen reactivity with 9000 human proteins. We identified cortactin, an intracellular protein that interacts with agrin/MuSK favoring AChR aggregation, as a new antigen in dSNMG. We then designed an in-house enzyme-linked immunosorbent assay as a screening assay and confirmed these results by western blot. We found that 19.7% of dSNMG patients had anti-cortactin antibodies. In contrast, patients with AChR+ MG or other autoimmune disorders and healthy controls were positive at significantly lower rates. Five percent of healthy controls were positive. In a recent study, we screened sera from 250 patients (AChR+ MG, MuSK+ MG, dSNMG) and 29 healthy controls. Cortactin antibodies were identified in 23.7% of dSNMG and 9.5% AChR+ MG patients (P = 0.02). None of the MuSK+ MG patients, patients with other autoimmune disorders, or healthy controls had antibodies against cortactin. Patients with dSNMG cortactin+ MG were negative for anti-striated muscle and anti-LRP4 antibodies. Patients with dSNMG cortactin+ MG presented ocular or mild generalized MG without bulbar symptoms. We conclude that cortactin autoantibodies are biomarkers of MG that, when present, suggest that the disease will be mild.
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Affiliation(s)
- Isabel Illa
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau - IIB Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Barcelona, Spain
| | - Elena Cortés-Vicente
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau - IIB Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Barcelona, Spain
| | - María Ángeles Martínez
- Department of Immunology, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Eduard Gallardo
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau - IIB Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Barcelona, Spain
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47
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Heckmann JM, Nel M. A unique subphenotype of myasthenia gravis. Ann N Y Acad Sci 2017; 1412:14-20. [DOI: 10.1111/nyas.13471] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 08/14/2017] [Accepted: 08/18/2017] [Indexed: 12/26/2022]
Affiliation(s)
- Jeannine M. Heckmann
- Neurology Division, Department of Medicine; University of Cape Town, Groote Schuur Hospital; Cape Town South Africa
- Neurology Research Group, Department of Medicine; University of Cape Town; Cape Town South Africa
| | - Melissa Nel
- Neurology Research Group, Department of Medicine; University of Cape Town; Cape Town South Africa
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48
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Yi JS, Guptill JT, Stathopoulos P, Nowak RJ, O'Connor KC. B cells in the pathophysiology of myasthenia gravis. Muscle Nerve 2017; 57:172-184. [PMID: 28940642 DOI: 10.1002/mus.25973] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2017] [Indexed: 12/21/2022]
Abstract
Myasthenia gravis (MG) is an archetypal autoimmune disease. The pathology is characterized by autoantibodies to the acetylcholine receptor (AChR) in most patients or to muscle-specific tyrosine kinase (MuSK) in others and to a growing number of other postsynaptic proteins in smaller subsets. A decrease in the number of functional AChRs or functional interruption of the AChR within the muscle end plate of the neuromuscular junction is caused by pathogenic autoantibodies. Although the molecular immunology underpinning the pathology is well understood, much remains to be learned about the cellular immunology contributing to the production of autoantibodies. This Review documents research concerning the immunopathology of MG, bringing together evidence principally from human studies with an emphasis on the role of adaptive immunity and B cells in particular. Proposed mechanisms for autoimmunity, which take into account that different types of MG may incorporate divergent immunopathology, are offered. Muscle Nerve 57: 172-184, 2018.
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Affiliation(s)
- John S Yi
- Division of Surgical Sciences, Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA
| | - Jeffrey T Guptill
- Department of Neurology, Neuromuscular Section, Duke University Medical Center, Durham, North Carolina, USA
| | - Panos Stathopoulos
- Department of Neurology, Yale School of Medicine, Room 353J, 300 George Street, New Haven, Connecticut, 06511, USA
| | - Richard J Nowak
- Department of Neurology, Yale School of Medicine, Room 353J, 300 George Street, New Haven, Connecticut, 06511, USA
| | - Kevin C O'Connor
- Department of Neurology, Yale School of Medicine, Room 353J, 300 George Street, New Haven, Connecticut, 06511, USA
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