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De Cicco T, Pęziński M, Wójcicka O, Pradhan BS, Jabłońska M, Rottner K, Prószyński TJ. Cortactin interacts with αDystrobrevin-1 and regulates murine neuromuscular junction morphology. Eur J Cell Biol 2024; 103:151409. [PMID: 38579603 DOI: 10.1016/j.ejcb.2024.151409] [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: 12/31/2023] [Revised: 03/24/2024] [Accepted: 03/29/2024] [Indexed: 04/07/2024] Open
Abstract
Neuromuscular junctions transmit signals from the nervous system to skeletal muscles, triggering their contraction, and their proper organization is essential for breathing and voluntary movements. αDystrobrevin-1 is a cytoplasmic component of the dystrophin-glycoprotein complex and has pivotal functions in regulating the integrity of muscle fibers and neuromuscular junctions. Previous studies identified that αDystrobrevin-1 functions in the organization of the neuromuscular junction and that its phosphorylation in the C-terminus is required in this process. Our proteomic screen identified several putative αDystrobrevin-1 interactors recruited to the Y730 site in phosphorylated and unphosphorylated states. Amongst various actin-modulating proteins, we identified the Arp2/3 complex regulator cortactin. We showed that similarly to αDystrobrevin-1, cortactin is strongly enriched at the neuromuscular postsynaptic machinery and obtained results suggesting that these two proteins interact in cell homogenates and at the neuromuscular junctions. Analysis of synaptic morphology in cortactin knockout mice showed abnormalities in the slow-twitching soleus muscle and not in the fast-twitching tibialis anterior. However, muscle strength examination did not reveal apparent deficits in knockout animals.
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Affiliation(s)
- Teresa De Cicco
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland; Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw 02-093, Poland
| | - Marcin Pęziński
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw 02-093, Poland
| | - Olga Wójcicka
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Bhola Shankar Pradhan
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Margareta Jabłońska
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Germany; Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, Braunschweig 38124, Germany
| | - Tomasz J Prószyński
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland; Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw 02-093, Poland.
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Martinez-Harms R, Barnett C, Alcantara M, Bril V. Clinical characteristics and treatment outcomes in patients with double-seronegative myasthenia gravis. Eur J Neurol 2024; 31:e16022. [PMID: 37531447 DOI: 10.1111/ene.16022] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 07/07/2023] [Accepted: 07/30/2023] [Indexed: 08/04/2023]
Abstract
BACKGROUND AND PURPOSE Double-seronegative myasthenia gravis (dSNMG) is defined as myasthenia gravis (MG) without detectable or low affinity antibodies to acetylcholine receptor (AChR) and muscle-specific kinase (MuSK). There are limited data on detailed clinical features and outcomes after treatment in dSNMG patients. The aim was to describe the clinical characteristics and outcomes in dSNMG patients based on MG scales. METHODS A retrospective study was performed of patients diagnosed with MG who had negative AChR or MuSK antibodies and they were compared with an AChR-positive MG cohort. Correlations were made with data from the first and last clinic visits, between demographics, clinical characteristics, treatment and disease severity, based on the Myasthenia Gravis Foundation of America category, Myasthenia Gravis Impairment Index (MGII), Patient Acceptable Symptom State and simple single question (SSQ). RESULTS Eighty patients met the inclusion criteria for dSNMG. The baseline MGII and SSQ scores in the dSNMG cohort showed no significant differences from the AChR group (p = 0.94 and p = 0.46). The dSNMG cohort MGII and SSQ scores improved significantly at the last clinical evaluation (p = 0.001 and p = 0.047). The MGII improvement in the AChR cohort was significantly better (p = 0.003). CONCLUSIONS The initial severity of dSNMG based on clinical scores is similar to antibody-positive MG patients. There is significant clinical improvement in dSNMG patients after therapy, measured in the last clinical evaluation. This supports an immune pathophysiology of many dSNMG patients.
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Affiliation(s)
- Rodrigo Martinez-Harms
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Toronto General Hospital, Toronto, Ontario, Canada
- University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Carolina Barnett
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Toronto General Hospital, Toronto, Ontario, Canada
- University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Monica Alcantara
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Toronto General Hospital, Toronto, Ontario, Canada
- University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Vera Bril
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Toronto General Hospital, Toronto, Ontario, Canada
- University Health Network, University of Toronto, Toronto, Ontario, Canada
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Simula ER, Zarbo IR, Arru G, Sechi E, Meloni R, Deiana GA, Solla P, Sechi LA. Antibody Response to HERV-K and HERV-W Envelope Epitopes in Patients with Myasthenia Gravis. Int J Mol Sci 2023; 25:446. [PMID: 38203616 PMCID: PMC10778599 DOI: 10.3390/ijms25010446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 12/20/2023] [Accepted: 12/25/2023] [Indexed: 01/12/2024] Open
Abstract
Myasthenia gravis is an antibody-mediated autoimmune neurological disorder characterized by impaired neuromuscular junction transmission, resulting in muscle weakness. Recently, the involvement of Human Endogenous Retroviruses (HERVs) in the pathophysiology of different immune-mediated and neurodegenerative diseases, such as multiple sclerosis, has been demonstrated. We aimed to investigate potential immune system involvement related to humoral responses targeting specific epitopes of HERV-K and HERV-W envelope proteins in myasthenia gravis. Myasthenia gravis patients were recruited in the Neurology Unit, while healthy controls were selected from the Blood Transfusion Center, both affiliated with AOU Sassari. Highly immunogenic antigens of HERV-K and HERV-W envelope proteins were identified using the Immune Epitope Database (IEDB) online tool. These epitopes were utilized in enzyme-linked immunosorbent assays (ELISA) to detect autoantibodies in serum directed against these sequences. The study involved 39 Healthy Donors and 47 MG patients, further categorized into subgroups based on the presence of autoantibodies: MG-AchR Ab+ (n = 17), MG-MuSK Ab+ (n = 7), double seronegative patients (MG-DSN, n = 18), MG-LRP4 Ab + (n = 4), and one patient with no antibodies data (n = 1). Our findings revealed high levels of autoantibodies in myasthenia gravis patients directed against the HERV-K-env-su(19-37), HERV-K-env-su(109-126), HERV-K-env-su(164-186), HERV-W-env(93-108), HERV-W-env(129-14), and HERV-W-env(248-262) epitopes. Notably, these results remained highly significant even when patients were subdivided into MG-AchR Ab+ and MG-DSN subgroups. Correlation analysis further revealed significant positive associations between the antibody levels against HERV-K and HERV-W families in patients, suggesting a synergistic action of the two HERVs in the pathology context since this correlation is absent in the control group. This study marks the first identification of a specific humoral response directed against defined epitopes of HERV-K and HERV-W envelope proteins in myasthenia gravis patients. These findings lay the foundation for future investigations aimed at elucidating the molecular mechanisms driving this immune response. The detection of these autoantibodies suggests the potential for novel biomarkers, especially within the MG-DSN patient subgroup, addressing the need for new biomarkers in this population.
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Affiliation(s)
- Elena Rita Simula
- Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43b, 07100 Sassari, Italy;
| | - Ignazio Roberto Zarbo
- Department of Medicine, Surgery and Pharmacy University of Sassari, Viale S. Pietro 10, 07100 Sassari, Italy; (I.R.Z.); (G.A.); (E.S.); (R.M.); (G.A.D.)
| | - Giannina Arru
- Department of Medicine, Surgery and Pharmacy University of Sassari, Viale S. Pietro 10, 07100 Sassari, Italy; (I.R.Z.); (G.A.); (E.S.); (R.M.); (G.A.D.)
| | - Elia Sechi
- Department of Medicine, Surgery and Pharmacy University of Sassari, Viale S. Pietro 10, 07100 Sassari, Italy; (I.R.Z.); (G.A.); (E.S.); (R.M.); (G.A.D.)
| | - Rossella Meloni
- Department of Medicine, Surgery and Pharmacy University of Sassari, Viale S. Pietro 10, 07100 Sassari, Italy; (I.R.Z.); (G.A.); (E.S.); (R.M.); (G.A.D.)
- Department of Medical Sciences and Public Health, University of Cagliari, 09124 Cagliari, Italy
| | - Giovanni Andrea Deiana
- Department of Medicine, Surgery and Pharmacy University of Sassari, Viale S. Pietro 10, 07100 Sassari, Italy; (I.R.Z.); (G.A.); (E.S.); (R.M.); (G.A.D.)
| | - Paolo Solla
- Department of Medicine, Surgery and Pharmacy University of Sassari, Viale S. Pietro 10, 07100 Sassari, Italy; (I.R.Z.); (G.A.); (E.S.); (R.M.); (G.A.D.)
| | - Leonardo Antonio Sechi
- Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43b, 07100 Sassari, Italy;
- Struttura Complessa Microbiologia e Virologia, Azienda Ospedaliera Universitaria, 07100 Sassari, Italy
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Chen X, Qiu J, Gao Z, Liu B, Zhang C, Yu W, Yang J, Shen Y, Qi L, Yao X, Sun H, Yang X. Myasthenia gravis: Molecular mechanisms and promising therapeutic strategies. Biochem Pharmacol 2023; 218:115872. [PMID: 37865142 DOI: 10.1016/j.bcp.2023.115872] [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: 09/03/2023] [Revised: 10/16/2023] [Accepted: 10/18/2023] [Indexed: 10/23/2023]
Abstract
Myasthenia gravis (MG) is a type of autoimmune disease caused by the blockage of neuromuscular junction transmission owing to the attack of autoantibodies on transmission-related proteins. Related antibodies, such as anti-AChR, anti-MuSK and anti-LRP4 antibodies, can be detected in most patients with MG. Although traditional therapies can control most symptoms, several challenges remain to be addressed, necessitating the development of more effective and safe treatment strategies for MG. With the in-depth exploration on the mechanism and immune targets of MG, effective therapies, especially therapies using biologicals, have been reported recently. Given the important roles of immune cells, cytokines and intercellular interactions in the pathological process of MG, B-cell targeted therapy, T-cell targeted therapy, proteasome inhibitors targeting plasma cell, complement inhibitors, FcRn inhibitors have been developed for the treatment of MG. Although these novel therapies exert good therapeutic effects, they may weaken the immunity and increase the risk of infection in MG patients. This review elaborates on the pathogenesis of MG and discusses the advantages and disadvantages of the strategies of traditional treatment and biologicals. In addition, this review emphasises that combined therapy may have better therapeutic effects and reducing the risk of side effects of treatments, which has great prospects for the treatment of MG. With the deepening of research on immunotherapy targets in MG, novel opportunities and challenges in the treatment of MG will be introduced.
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Affiliation(s)
- Xin Chen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, Department of Neurology, Affiliated Hospital of Nantong University, Nantong University, Nantong, Jiangsu Province 226001, PR China
| | - Jiayi Qiu
- Department of Clinical Medicine, Medical College, Nantong University, Nantong, Jiangsu Province 226001, PR China
| | - Zihui Gao
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, Department of Neurology, Affiliated Hospital of Nantong University, Nantong University, Nantong, Jiangsu Province 226001, PR China
| | - Boya Liu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, Department of Neurology, Affiliated Hospital of Nantong University, Nantong University, Nantong, Jiangsu Province 226001, PR China
| | - Chen Zhang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, Department of Neurology, Affiliated Hospital of Nantong University, Nantong University, Nantong, Jiangsu Province 226001, PR China
| | - Weiran Yu
- Department of Clinical Medicine, Medical College, Nantong University, Nantong, Jiangsu Province 226001, PR China
| | - Jiawen Yang
- Department of Clinical Medicine, Medical College, Nantong University, Nantong, Jiangsu Province 226001, PR China
| | - Yuntian Shen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, Department of Neurology, Affiliated Hospital of Nantong University, Nantong University, Nantong, Jiangsu Province 226001, PR China
| | - Lei Qi
- Department of Emergency Medicine, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province 226001, PR China
| | - Xinlei Yao
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, Department of Neurology, Affiliated Hospital of Nantong University, Nantong University, Nantong, Jiangsu Province 226001, PR China.
| | - Hualin Sun
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, Department of Neurology, Affiliated Hospital of Nantong University, Nantong University, Nantong, Jiangsu Province 226001, PR China.
| | - Xiaoming Yang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, Department of Neurology, Affiliated Hospital of Nantong University, Nantong University, Nantong, Jiangsu Province 226001, PR China.
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Oeztuerk M, Henes A, Schroeter CB, Nelke C, Quint P, Theissen L, Meuth SG, Ruck T. Current Biomarker Strategies in Autoimmune Neuromuscular Diseases. Cells 2023; 12:2456. [PMID: 37887300 PMCID: PMC10605022 DOI: 10.3390/cells12202456] [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: 09/11/2023] [Revised: 10/09/2023] [Accepted: 10/12/2023] [Indexed: 10/28/2023] Open
Abstract
Inflammatory neuromuscular disorders encompass a diverse group of immune-mediated diseases with varying clinical manifestations and treatment responses. The identification of specific biomarkers has the potential to provide valuable insights into disease pathogenesis, aid in accurate diagnosis, predict disease course, and monitor treatment efficacy. However, the rarity and heterogeneity of these disorders pose significant challenges in the identification and implementation of reliable biomarkers. Here, we aim to provide a comprehensive review of biomarkers currently established in Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), myasthenia gravis (MG), and idiopathic inflammatory myopathy (IIM). It highlights the existing biomarkers in these disorders, including diagnostic, prognostic, predictive and monitoring biomarkers, while emphasizing the unmet need for additional specific biomarkers. The limitations and challenges associated with the current biomarkers are discussed, and the potential implications for disease management and personalized treatment strategies are explored. Collectively, biomarkers have the potential to improve the management of inflammatory neuromuscular disorders. However, novel strategies and further research are needed to establish clinically meaningful biomarkers.
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Affiliation(s)
| | | | | | | | | | | | | | - Tobias Ruck
- Department of Neurology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; (M.O.); (A.H.); (P.Q.)
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Stergiou C, Williams R, Fleming JR, Zouvelou V, Ninou E, Andreetta F, Rinaldi E, Simoncini O, Mantegazza R, Bogomolovas J, Tzartos J, Labeit S, Mayans O, Tzartos S. Immunological and Structural Characterization of Titin Main Immunogenic Region; I110 Domain Is the Target of Titin Antibodies in Myasthenia Gravis. Biomedicines 2023; 11:biomedicines11020449. [PMID: 36830985 PMCID: PMC9952892 DOI: 10.3390/biomedicines11020449] [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: 12/27/2022] [Revised: 01/25/2023] [Accepted: 02/01/2023] [Indexed: 02/08/2023] Open
Abstract
Myasthenia gravis (MG) is an autoimmune disease caused by antibodies targeting the neuromuscular junction (NJ) of skeletal muscles. The major MG autoantigen is nicotinic acetylcholine receptor. Other autoantigens at the NJ include MuSK, LRP4 and agrin. Autoantibodies to the intra-sarcomeric striated muscle-specific gigantic protein titin, although not directed to the NJ, are invaluable biomarkers for thymoma and MG disease severity. Thymus and thymoma are critical in MG mechanisms and management. Titin autoantibodies bind to a 30 KDa titin segment, the main immunogenic region (MIR), consisting of an Ig-FnIII-FnIII 3-domain tandem, termed I109-I111. In this work, we further resolved the localization of titin epitope(s) to facilitate the development of more specific anti-titin diagnostics. For this, we expressed protein samples corresponding to 8 MIR and non-MIR titin fragments and tested 77 anti-titin sera for antibody binding using ELISA, competition experiments and Western blots. All anti-MIR antibodies were bound exclusively to the central MIR domain, I110, and to its containing titin segments. Most antibodies were bound also to SDS-denatured I110 on Western blots, suggesting that their epitope(s) are non-conformational. No significant difference was observed between thymoma and non-thymoma patients or between early- and late-onset MG. In addition, atomic 3D-structures of the MIR and its subcomponents were elucidated using X-ray crystallography. These immunological and structural data will allow further studies into the atomic determinants underlying titin-based autoimmunity, improved diagnostics and how to eventually treat titin autoimmunity associated co-morbidities.
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Affiliation(s)
| | - Rhys Williams
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | | | - Vasiliki Zouvelou
- 1st Neurology Department, Eginition Hospital, National and Kapodistrian University of Athens, 157 72 Athens, Greece
| | | | - Francesca Andreetta
- Fondazione I.R.C.C.S., Istituto Neurologico Carlo Besta, 20133 Milano, Italy
| | - Elena Rinaldi
- Fondazione I.R.C.C.S., Istituto Neurologico Carlo Besta, 20133 Milano, Italy
| | - Ornella Simoncini
- Fondazione I.R.C.C.S., Istituto Neurologico Carlo Besta, 20133 Milano, Italy
| | - Renato Mantegazza
- Fondazione I.R.C.C.S., Istituto Neurologico Carlo Besta, 20133 Milano, Italy
| | - Julius Bogomolovas
- School of Medicine, University of California, La Jolla, San Diego, CA 92093, USA
| | - John Tzartos
- School of Medicine, Attikon University Hospital, National and Kapodistrian University of Athens, 124 62 Athens, Greece
| | - Siegfried Labeit
- DZHK Partner Site Mannheim-Heidelberg, Medical Faculty Mannheim, University of Heidelberg, 68167 Mannheim, Germany
- Myomedix GmbH, 69151 Neckargemuend, Germany
| | - Olga Mayans
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Socrates Tzartos
- Tzartos NeuroDiagnostics, 115 23 Athens, Greece
- Hellenic Pasteur Institute, 115 21 Athens, Greece
- Department of Pharmacy, University of Patras, 265 00 Patras, Greece
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Harsini S, Rezaei N. Autoimmune diseases. Clin Immunol 2023. [DOI: 10.1016/b978-0-12-818006-8.00001-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Chung HY, Kim MJ, Kim SW, Oh J, Shin HY. Development and Application of a Cell-Based Assay for LRP4 Antibody Associated With Myasthenia Gravis. J Clin Neurol 2023; 19:60-66. [PMID: 36606647 PMCID: PMC9833872 DOI: 10.3988/jcn.2023.19.1.60] [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] [Received: 05/20/2022] [Revised: 07/25/2022] [Accepted: 07/29/2022] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND AND PURPOSE Among patients with double-seronegative myasthenia gravis (dSN-MG) who do not have detectable antibodies against acetylcholine receptor or muscle-specific tyrosine kinase, autoantibodies against low-density lipoprotein receptor-related protein 4 (LRP4-Ab) have been detected recently. The purpose of this study was to develop an in-house cell-based assay (CBA) to detect LRP4-Ab and to apply it to samples from patients with MG. METHODS The complementary DNA of LRP4 fused into a vector plasmid containing GFP was transfected into human embryonic kidney 293 (HEK293) cells. LRP4 expression in the transfected HEK293 cells was assessed using the reverse-transcription polymerase chain reaction (RT-PCR), Western blotting, and immunocytochemistry. The CBA included 252 sera collected from 202 patients with MG and 38 with other neuromuscular diseases, and 12 healthy controls. The transfected HEK293 cells were incubated using sera and antihuman immunoglobulin G antibodies conjugated with Alexa Fluor 594. The presence of LRP4-Ab was determined based on the fluorescence intensity and the localization in fluorescence microscopy. RESULTS The expressions of the mRNA and protein of LRP4 in the transfected HEK293 cells were confirmed using RT-PCR and Western blotting, respectively. Immunocytochemistry indicated LPR4 expression on the cell membrane. Among 202 patients with MG including 53 with dSN-MG, LRP4-Ab were positive in 3 patients who were all double seronegative. LRP4-Ab were not detected in the patients with other neuromuscular diseases or the healthy controls. CONCLUSIONS A CBA for detecting LRP4-Ab associated with MG has been developed, and was used to find LRP4-Ab in the sera of patients with MG.
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Affiliation(s)
- Hye Yoon Chung
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - Min Ju Kim
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea.,Graduate Program of Nano Science and Technology, Yonsei University, Seoul, Korea
| | - Seung Woo Kim
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - Jeeyoung Oh
- Department of Neurology, Konkuk University Medical Center, School of Medicine, Konkuk University, Seoul, Korea
| | - Ha Young Shin
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
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Michail M, Zouvelou V, Belimezi M, Haroniti A, Zouridakis M, Zisimopoulou P. Analysis of nAChR Autoantibodies Against Extracellular Epitopes in MG Patients. Front Neurol 2022; 13:858998. [PMID: 35418927 PMCID: PMC8995881 DOI: 10.3389/fneur.2022.858998] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 02/28/2022] [Indexed: 01/12/2023] Open
Abstract
Myasthenia gravis (MG) is an autoimmune disorder caused by autoantibodies targeting components of the postsynaptic membrane of the neuromuscular junction (NMJ), leading to neuromuscular transmission deficiency. In the vast majority of patients, these autoantibodies target the nicotinic acetylcholine receptor (nAChR), a heteropentameric ion channel anchored to the postsynaptic membrane of the NMJ. Autoantibodies in patients with MG may target all the subunits of the receptor at both their extracellular and intracellular regions. Here, we combine immunoadsorption with a cell-based assay to examine the specificity of the patients' autoantibodies against the extracellular part of the nAChR. Our results reveal that these autoantibodies can be divided into distinct groups, based on their target, with probably different impacts on disease severity. Although our findings are based on a small sample group of patients, they strongly support that additional analysis of the specificity of the autoantibodies of patients with MG could serve as a valuable tool for the clinicians' decision on the treatment strategy to be followed.
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Affiliation(s)
- Maria Michail
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece.,Department of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - Vasiliki Zouvelou
- Department of Neurology, Eginition Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Maria Belimezi
- Diagnostic Department, Hellenic Pasteur Institute, Athens, Greece
| | - Anna Haroniti
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece
| | - Marios Zouridakis
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece
| | - Paraskevi Zisimopoulou
- Laboratory of Molecular Neurobiology and Immunology, Hellenic Pasteur Institute, Athens, Greece
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Vanoli F, Mantegazza R. Antibody Therapies in Autoimmune Neuromuscular Junction Disorders: Approach to Myasthenic Crisis and Chronic Management. Neurotherapeutics 2022; 19:897-910. [PMID: 35165857 PMCID: PMC9294078 DOI: 10.1007/s13311-022-01181-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/02/2022] [Indexed: 02/06/2023] Open
Abstract
Myasthenia gravis (MG) is a neurological autoimmune disorder characterized by muscle weakness and fatigue. It is a B cell-mediated disease caused by pathogenic antibodies directed against various components of the neuromuscular junction (NMJ). Despite the wide range of adverse effects, current treatment is still based on non-specific immunosuppression, particularly on long-term steroid usage. The increasing knowledge regarding the pathogenic mechanisms of MG has however allowed to create more target-specific therapies. A very attractive therapeutic approach is currently offered by monoclonal antibodies (mAbs), given their ability to specifically and effectively target different immunopathological pathways, such as the complement cascade, B cell-related cluster of differentiation (CD) proteins, and the human neonatal Fc receptor (FcRn). Up to now, eculizumab, a C5-directed mAb, has been approved for the treatment of generalized MG (gMG) and efgartigimod, a FcRn inhibitor, has just been approved by the U.S. Food and Drug Administration for the treatment of anti-acetylcholine receptor (AChR) antibody positive gMG. Other mAbs are currently under investigation with encouraging preliminary results, further enriching the new range of therapeutic possibilities for MG. This review article provides an overview of the present status of mAb-based therapies for MG, which offer an exciting promise for better outcomes by setting the basis of a precision medicine approach.
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Affiliation(s)
- Fiammetta Vanoli
- Neuroimmunology and Neuromuscular Disease Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
- Department of Human Neurosciences, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Renato Mantegazza
- Neuroimmunology and Neuromuscular Disease Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.
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Pinal-Fernandez I, Pak K, Gil-Vila A, Baucells A, Plotz B, Casal-Dominguez M, Derfoul A, Martinez MA, Selva-O’Callaghan A, Sabbagh S, Casciola-Rosen L, Albayda J, Paik J, Tiniakou E, Danoff SK, Lloyd TE, Miller FW, Rider LG, Christopher-Stine L, Mammen AL. Anti-Cortactin Autoantibodies Are Associated With Key Clinical Features in Adult Myositis But Are Rarely Present in Juvenile Myositis. Arthritis Rheumatol 2022; 74:358-364. [PMID: 34313394 PMCID: PMC8792092 DOI: 10.1002/art.41931] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 06/15/2021] [Accepted: 06/22/2021] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To define the prevalence and clinical phenotype of anti-cortactin autoantibodies in adult and juvenile myositis. METHODS In this longitudinal cohort study, anti-cortactin autoantibody titers were assessed by enzyme-linked immunosorbent assay in 670 adult myositis patients and 343 juvenile myositis patients as well as in 202 adult healthy controls and 90 juvenile healthy controls. The prevalence of anti-cortactin autoantibodies was compared among groups. Clinical features of patients with and those without anti-cortactin autoantibodies were also compared. RESULTS Anti-cortactin autoantibodies were more common in adult dermatomyositis (DM) patients (15%; P = 0.005), particularly those with coexisting anti-Mi-2 autoantibodies (24%; P = 0.03) or anti-NXP-2 autoantibodies (23%; P = 0.04). In adult myositis, anti-cortactin was associated with DM skin involvement (62% of patients with anti-cortactin versus 38% of patients without anti-cortactin; P = 0.03), dysphagia (36% versus 17%; P = 0.02) and coexisting anti-Ro 52 autoantibodies (47% versus 26%; P = 0.001) or anti-NT5c1a autoantibodies (59% versus 33%; P = 0.001). Moreover, the titers of anti-cortactin antibodies were higher in patients with interstitial lung disease (0.15 versus 0.12 arbitrary units; P = 0.03). The prevalence of anti-cortactin autoantibodies was not different in juvenile myositis patients (2%) or in any juvenile myositis subgroup compared to juvenile healthy controls (4%). Nonetheless, juvenile myositis patients with these autoantibodies had a higher prevalence of "mechanic's hands" (25% versus 7%; P = 0.03), a higher number of hospitalizations (2.9 versus 1.3; P = 0.04), and lower peak creatine kinase values (368 versus 818 IU/liter; P = 0.02) than those without anti-cortactin. CONCLUSION The prevalence of anti-cortactin autoantibodies is increased in adult DM patients with coexisting anti-Mi-2 or anti-NXP-2 autoantibodies. In adults, anti-cortactin autoantibodies are associated with dysphagia and interstitial lung disease.
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Affiliation(s)
- Iago Pinal-Fernandez
- Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Faculty of Health Sciences, and Faculty of Computer Science, Multimedia and Telecommunications, Universitat Oberta de Catalunya, Barcelona, Spain
| | - Katherine Pak
- Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland
| | - Albert Gil-Vila
- Vall d’Hebron Hospital, Barcelona, Spain.,Autonomous University of Barcelona, Barcelona, Spain
| | | | - Benjamin Plotz
- Division of Rheumatology, New York University Langone Health, New York, NY
| | - Maria Casal-Dominguez
- Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Assia Derfoul
- Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland
| | | | | | - Sara Sabbagh
- Division of Rheumatology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Livia Casciola-Rosen
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Jemima Albayda
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Julie Paik
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Eleni Tiniakou
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Sonye K. Danoff
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Thomas E. Lloyd
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Frederick W. Miller
- Environmental Autoimmunity Group, Clinical Research Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Bethesda, MD
| | - Lisa G. Rider
- Environmental Autoimmunity Group, Clinical Research Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Bethesda, MD
| | - Lisa Christopher-Stine
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Andrew L. Mammen
- Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
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12
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Beladakere Ramaswamy S, Singh S, Hooshmand S, Junsang C, Sweeney M, Govindarajan R. Current and Upcoming Treatment Modalities in Myasthenia Gravis. J Clin Neuromuscul Dis 2021; 23:75-99. [PMID: 34808650 DOI: 10.1097/cnd.0000000000000377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
ABSTRACT Myasthenia gravis (MG) is one of the extensively studied autoimmune disorder. There has been a dramatic increase in research to further understand molecular pathogenesis of MG and clinical trials for new drugs in MG treatment in the past decade. This review article is to consolidate the available information in simple terms with students, residents, and fellows as target audience for easy learning and help application of this knowledge to clinical practice.
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13
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Fralish Z, Lotz EM, Chavez T, Khodabukus A, Bursac N. Neuromuscular Development and Disease: Learning From in vitro and in vivo Models. Front Cell Dev Biol 2021; 9:764732. [PMID: 34778273 PMCID: PMC8579029 DOI: 10.3389/fcell.2021.764732] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/06/2021] [Indexed: 01/02/2023] Open
Abstract
The neuromuscular junction (NMJ) is a specialized cholinergic synaptic interface between a motor neuron and a skeletal muscle fiber that translates presynaptic electrical impulses into motor function. NMJ formation and maintenance require tightly regulated signaling and cellular communication among motor neurons, myogenic cells, and Schwann cells. Neuromuscular diseases (NMDs) can result in loss of NMJ function and motor input leading to paralysis or even death. Although small animal models have been instrumental in advancing our understanding of the NMJ structure and function, the complexities of studying this multi-tissue system in vivo and poor clinical outcomes of candidate therapies developed in small animal models has driven the need for in vitro models of functional human NMJ to complement animal studies. In this review, we discuss prevailing models of NMDs and highlight the current progress and ongoing challenges in developing human iPSC-derived (hiPSC) 3D cell culture models of functional NMJs. We first review in vivo development of motor neurons, skeletal muscle, Schwann cells, and the NMJ alongside current methods for directing the differentiation of relevant cell types from hiPSCs. We further compare the efficacy of modeling NMDs in animals and human cell culture systems in the context of five NMDs: amyotrophic lateral sclerosis, myasthenia gravis, Duchenne muscular dystrophy, myotonic dystrophy, and Pompe disease. Finally, we discuss further work necessary for hiPSC-derived NMJ models to function as effective personalized NMD platforms.
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Affiliation(s)
- Zachary Fralish
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, United States
| | - Ethan M Lotz
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, United States
| | - Taylor Chavez
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, United States
| | - Alastair Khodabukus
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, United States
| | - Nenad Bursac
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, United States
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14
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Circulating Biomarkers in Neuromuscular Disorders: What Is Known, What Is New. Biomolecules 2021; 11:biom11081246. [PMID: 34439911 PMCID: PMC8393752 DOI: 10.3390/biom11081246] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 08/16/2021] [Accepted: 08/19/2021] [Indexed: 02/07/2023] Open
Abstract
The urgent need for new therapies for some devastating neuromuscular diseases (NMDs), such as Duchenne muscular dystrophy or amyotrophic lateral sclerosis, has led to an intense search for new potential biomarkers. Biomarkers can be classified based on their clinical value into different categories: diagnostic biomarkers confirm the presence of a specific disease, prognostic biomarkers provide information about disease course, and therapeutic biomarkers are designed to predict or measure treatment response. Circulating biomarkers, as opposed to instrumental/invasive ones (e.g., muscle MRI or nerve ultrasound, muscle or nerve biopsy), are generally easier to access and less “time-consuming”. In addition to well-known creatine kinase, other promising molecules seem to be candidate biomarkers to improve the diagnosis, prognosis and prediction of therapeutic response, such as antibodies, neurofilaments, and microRNAs. However, there are some criticalities that can complicate their application: variability during the day, stability, and reliable performance metrics (e.g., accuracy, precision and reproducibility) across laboratories. In the present review, we discuss the application of biochemical biomarkers (both validated and emerging) in the most common NMDs with a focus on their diagnostic, prognostic/predictive and therapeutic application, and finally, we address the critical issues in the introduction of new biomarkers.
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15
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Comment to "Autoantibodies to cortactin and agrin in sera of patients with myasthenia gravis". J Neuroimmunol 2021; 358:577659. [PMID: 34273889 DOI: 10.1016/j.jneuroim.2021.577659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 06/30/2021] [Accepted: 07/08/2021] [Indexed: 11/23/2022]
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16
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Fc-Receptor Targeted Therapies for the Treatment of Myasthenia gravis. Int J Mol Sci 2021; 22:ijms22115755. [PMID: 34071155 PMCID: PMC8198115 DOI: 10.3390/ijms22115755] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 12/16/2022] Open
Abstract
Myasthenia gravis (MG) is an autoimmune disease in which immunoglobulin G (IgG) antibodies (Abs) bind to acetylcholine receptors (AChR) or to functionally related molecules in the postsynaptic membrane at the neuromuscular junction. IgG crystallizable fragment (Fc)-mediated effector functions, such as antibody-dependent complement deposition, contribute to disease development and progression. Despite progress in understanding Ab-mediated disease mechanisms, immunotherapy of MG remained rather unspecific with corticosteroids and maintenance with immunosuppressants as first choice drugs for most patients. More specific therapeutic IgG Fc-based platforms that reduce serum half-life or effector functions of pathogenic MG-related Abs are currently being developed, tested in clinical trials or have recently been successfully translated into the clinic. In this review, we illustrate mechanisms of action and clinical efficacies of emerging Fc-mediated therapeutics such as neonatal Fc receptor (FcRn)-targeting agents. Furthermore, we evaluate prospects of therapies targeting classical Fc receptors that have shown promising therapeutic efficacy in other antibody-mediated conditions. Increased availability of Fc- and Fc receptor-targeting biologics might foster the development of personalized immunotherapies with the potential to induce sustained disease remission in patients with MG.
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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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18
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Doppler K, Hemprich A, Haarmann A, Brecht I, Franke M, Kröger S, Villmann C, Sommer C. Autoantibodies to cortactin and agrin in sera of patients with myasthenia gravis. J Neuroimmunol 2021; 356:577588. [PMID: 33962172 DOI: 10.1016/j.jneuroim.2021.577588] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 04/13/2021] [Accepted: 04/22/2021] [Indexed: 12/13/2022]
Abstract
Autoantibodies against agrin and cortactin have been described in patients with myasthenia gravis. To further validate and characterize these autoantibodies, sera and/or plasma exchange material of 135 patients with myasthenia gravis were screened for anti-agrin or anti-cortactin autoantibodies. Autoantibodies against cortactin were detected in three patients and two controls and could be confirmed by cell-based assays using cortactin-transfected human embryonic kidney cells in both controls and one patient, but were not detectable in follow-up sera of the three patients. We did not detect any autoantibodies against agrin. The clinical phenotype of anti-cortactin-positive patients varied, arguing against a relevant pathogenic role.
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Affiliation(s)
- Kathrin Doppler
- University Hospital Würzburg, Department of Neurology, Josef-Schneider-Str. 11, 97080 Würzburg, Germany.
| | - Antonia Hemprich
- University Hospital Würzburg, Department of Neurology, Josef-Schneider-Str. 11, 97080 Würzburg, Germany.
| | - Axel Haarmann
- University Hospital Würzburg, Department of Neurology, Josef-Schneider-Str. 11, 97080 Würzburg, Germany.
| | - Isabel Brecht
- University Hospital Würzburg, Department of Neurology, Josef-Schneider-Str. 11, 97080 Würzburg, Germany
| | - Maximilian Franke
- University Hospital Würzburg, Department of Neurology, Josef-Schneider-Str. 11, 97080 Würzburg, Germany.
| | - Stephan Kröger
- Ludwig-Maximilians-Universität München, Department of Physiological Genomics, BioMedical Center, Großhaderner Str. 9, 82152 Planegg-Martinsried, Germany.
| | - Carmen Villmann
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany.
| | - Claudia Sommer
- University Hospital Würzburg, Department of Neurology, Josef-Schneider-Str. 11, 97080 Würzburg, Germany.
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19
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Sheikh S, Alvi U, Soliven B, Rezania K. Drugs That Induce or Cause Deterioration of Myasthenia Gravis: An Update. J Clin Med 2021; 10:jcm10071537. [PMID: 33917535 PMCID: PMC8038781 DOI: 10.3390/jcm10071537] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/24/2021] [Accepted: 03/31/2021] [Indexed: 12/20/2022] Open
Abstract
Myasthenia gravis (MG) is an autoimmune neuromuscular disorder which is characterized by presence of antibodies against acetylcholine receptors (AChRs) or other proteins of the postsynaptic membrane resulting in damage to postsynaptic membrane, decreased number of AChRs or blocking of the receptors by autoantibodies. A number of drugs such as immune checkpoint inhibitors, penicillamine, tyrosine kinase inhibitors and interferons may induce de novo MG by altering the immune homeostasis mechanisms which prevent emergence of autoimmune diseases such as MG. Other drugs, especially certain antibiotics, antiarrhythmics, anesthetics and neuromuscular blockers, have deleterious effects on neuromuscular transmission, resulting in increased weakness in MG or MG-like symptoms in patients who do not have MG, with the latter usually being under medical circumstances such as kidney failure. This review summarizes the drugs which can cause de novo MG, MG exacerbation or MG-like symptoms in nonmyasthenic patients.
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20
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Álvarez-Velasco R, Gutiérrez-Gutiérrez G, Trujillo JC, Martínez E, Segovia S, Arribas-Velasco M, Fernández G, Paradas C, Vélez-Gómez B, Casasnovas C, Nedkova V, Guerrero-Sola A, Ramos-Fransi A, Martínez-Piñeiro A, Pardo J, Sevilla T, Gómez-Caravaca MT, López de Munain A, Jericó I, Pelayo-Negro AL, Martín MA, Morgado Y, Mendoza MD, Pérez-Pérez H, Rojas-García R, Turon-Sans J, Querol L, Gallardo E, Illa I, Cortés-Vicente E. Clinical characteristics and outcomes of thymoma-associated myasthenia gravis. Eur J Neurol 2021; 28:2083-2091. [PMID: 33721382 DOI: 10.1111/ene.14820] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 02/26/2021] [Accepted: 03/10/2021] [Indexed: 01/10/2023]
Abstract
BACKGROUND AND PURPOSE Prognosis of myasthenia gravis (MG) in patients with thymoma is not well established. Moreover, it is not clear whether thymoma recurrence or unresectable lesions entail a worse prognosis of MG. METHODS This multicenter study was based on data from a Spanish neurologist-driven MG registry. All patients were aged >18 years at onset and had anti-acetylcholine receptor antibodies. We compared the clinical data of thymomatous and nonthymomatous patients. Prognosis of patients with recurrent or nonresectable thymomas was assessed. RESULTS We included 964 patients from 15 hospitals; 148 (15.4%) had thymoma-associated MG. Median follow-up time was 4.6 years. At onset, thymoma-associated MG patients were younger (52.0 vs. 60.4 years, p < 0.001), had more generalized symptoms (odds ratio [OR]: 3.02, 95% confidence interval [CI]: 1.95-4.68, p < 0.001) and more severe clinical forms according to the Myasthenia Gravis Foundation of America (MGFA) scale (OR: 1.6, 95% CI: 1.15-2.21, p = 0.005). Disease severity based on MGFA postintervention status (MGFA-PIS) was higher in thymomatous patients at 1 year, 5 years, and the end of follow-up. Treatment refractoriness and mortality were also higher (OR: 2.28, 95% CI: 1.43-3.63, p = 0.001; hazard ratio: 2.46, 95% CI: 1.47-4.14, p = 0.001). Myasthenic symptoms worsened in 13 of 27 patients with recurrences, but differences in long-term severity were not significant. Fifteen thymomatous patients had nonresectable thymomas with worse MGFA-PIS and higher mortality at the end of follow-up. CONCLUSIONS Thymoma-associated MG patients had more severe myasthenic symptoms and worse prognosis. Thymoma recurrence was frequently associated with transient worsening of MG, but long-term prognosis did not differ from nonrecurrent thymoma. Patients with nonresectable thymoma tended to present severe forms of MG.
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Affiliation(s)
- Rodrigo Álvarez-Velasco
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.,Department of Medicine, Universitat Autónoma de Barcelona, Barcelona, Spain.,Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Gerardo Gutiérrez-Gutiérrez
- Department of Neurology, Hospital Universitario Infanta Sofía, Universidad Europea de Madrid, San Sebastián de los Reyes, Spain
| | - Juan Carlos Trujillo
- Department of Medicine, Universitat Autónoma de Barcelona, Barcelona, Spain.,Department of Thoracic Surgery, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Elisabeth Martínez
- Department of Thoracic Surgery, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Sonia Segovia
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Marina Arribas-Velasco
- Department of Neurology, Hospital Universitario Infanta Sofía, Universidad Europea de Madrid, San Sebastián de los Reyes, Spain
| | - Guillermo Fernández
- Department of Neurology, Hospital Universitario Infanta Sofía, Universidad Europea de Madrid, San Sebastián de los Reyes, Spain
| | - Carmen Paradas
- Neurology Department, Neuromuscular Disorders Unit, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Beatriz Vélez-Gómez
- Neurology Department, Neuromuscular Disorders Unit, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain
| | - Carlos Casasnovas
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Neuromuscular Unit, Neurology Department, Hospital Universitario de Bellvitge, Hospitalet de Llobregat, Barcelona, Spain.,Neurometabolic Diseases Group, Bellvitge Biomedical Research Institute (IDIBELL), Hospitalet de Llobregat, Barcelona, Spain
| | - Velina Nedkova
- Neuromuscular Unit, Neurology Department, Hospital Universitario de Bellvitge, Hospitalet de Llobregat, Barcelona, Spain
| | - Antonio Guerrero-Sola
- Neuromuscular Diseases and ALS Unit, Department of Neurology, Institute of Neurosciences, Hospital Universitario Clínico San Carlos, Madrid, Spain
| | - Alba Ramos-Fransi
- Department of Medicine, Universitat Autónoma de Barcelona, Barcelona, Spain.,Neuromuscular Diseases Unit, Department of Neurology, Hospital Germans Trias i Pujol, Badalona, Spain
| | - Alicia Martínez-Piñeiro
- Department of Medicine, Universitat Autónoma de Barcelona, Barcelona, Spain.,Neuromuscular Diseases Unit, Department of Neurology, Hospital Germans Trias i Pujol, Badalona, Spain
| | - Julio Pardo
- Department of Neurology, Hospital Clínico de Santiago de Compostela, Santiago de Compostela, Spain
| | - Teresa Sevilla
- Neuromuscular Unit, Neurology Department, Hospital Universitari i Politècnic La Fe, Department of Medicine, Universitat de València, and Biomedical Research Institute La Fe (IIS La Fe), Valencia, Spain
| | | | - Adolfo López de Munain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain.,Neuromuscular Unit, Hospital Universitario de Donostia. Biodonostia Health Research Institute, University of the Basque Country, Gipuzkoa, Spain
| | - Ivonne Jericó
- Department of Neurology, Complejo Hospitalario de Navarra, IdisNa (Instituto Investigación Sanitaria Navarra), Pamplona, Spain
| | - Ana L Pelayo-Negro
- Department of Neurology, Hospital Universitario Marqués de Valdecilla, University of Cantabria, Santander, Spain
| | | | - Yolanda Morgado
- Department of Neurology, Hospital Universitario de Valme, Seville, Spain
| | - María Dolores Mendoza
- Hospital Universitario de Gran Canaria Doctor Negrín, Las Palmas de Gran Canaria, Spain
| | - Helena Pérez-Pérez
- Department of Neurology, Complejo Hospitalario Universitario de Canarias, Santa Cruz de Tenerife, Spain
| | - Ricard Rojas-García
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.,Department of Medicine, Universitat Autónoma de Barcelona, Barcelona, Spain.,Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Janina Turon-Sans
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.,Department of Medicine, Universitat Autónoma de Barcelona, Barcelona, Spain.,Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Luis Querol
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.,Department of Medicine, Universitat Autónoma de Barcelona, Barcelona, Spain.,Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Eduard Gallardo
- Department of Medicine, Universitat Autónoma de Barcelona, Barcelona, Spain.,Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Isabel Illa
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.,Department of Medicine, Universitat Autónoma de Barcelona, Barcelona, Spain.,Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Elena Cortés-Vicente
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.,Department of Medicine, Universitat Autónoma de Barcelona, Barcelona, Spain.,Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
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21
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Frykman H, Kumar P, Oger J. Immunopathology of Autoimmune Myasthenia Gravis: Implications for Improved Testing Algorithms and Treatment Strategies. Front Neurol 2020; 11:596621. [PMID: 33362698 PMCID: PMC7755715 DOI: 10.3389/fneur.2020.596621] [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: 08/19/2020] [Accepted: 11/19/2020] [Indexed: 12/13/2022] Open
Abstract
Myasthenia gravis (MG) is a heterogeneous condition, characterized by autoantibodies (Abs) that target functionally important structures within neuromuscular junctions (NMJ), thus affecting nerve-to-muscle transmission. MG patients are more often now subgrouped based on the profile of serum autoantibodies, which segregate with clinical presentation, immunopathology, and their response to therapies. The serological testing plays an essential role in confirming MG diagnosis and guiding disease management, although a small percentage of MG patients remain negative for antibodies. With the advancements in new highly effective pathophysiologically-specific immunotherapeutic options, it has become increasingly important to identify the specific Abs responsible for the pathogenicity in individual MG patients. There are several new assays and protocols being developed for the improved detection of Abs in MG patients. This review focuses on the divergent immunopathological mechanisms in MG, and discusses their relevance to improved diagnostic and treatment. We propose a comprehensive "reflex testing," algorithm for the presence of MG autoantibodies, and foresee that in the near future, the convenience and specificity of novel assays will permit the clinicians to consider them into routine systematic testing, thus stimulating laboratories to make these tests available. Moreover, adopting treatment driven testing algorithms will be crucial to identify subgroups of patients potentially benefiting from novel immunotherapies for MG.
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Affiliation(s)
- Hans Frykman
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada.,BC Neuroimmunology Lab, University of British Columbia, Vancouver, BC, Canada
| | - Pankaj Kumar
- BC Neuroimmunology Lab, University of British Columbia, Vancouver, BC, Canada
| | - Joel Oger
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada.,BC Neuroimmunology Lab, University of British Columbia, Vancouver, BC, Canada
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22
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Rodríguez Cruz PM, Cossins J, Beeson D, Vincent A. The Neuromuscular Junction in Health and Disease: Molecular Mechanisms Governing Synaptic Formation and Homeostasis. Front Mol Neurosci 2020; 13:610964. [PMID: 33343299 PMCID: PMC7744297 DOI: 10.3389/fnmol.2020.610964] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 10/30/2020] [Indexed: 12/28/2022] Open
Abstract
The neuromuscular junction (NMJ) is a highly specialized synapse between a motor neuron nerve terminal and its muscle fiber that are responsible for converting electrical impulses generated by the motor neuron into electrical activity in the muscle fibers. On arrival of the motor nerve action potential, calcium enters the presynaptic terminal, which leads to the release of the neurotransmitter acetylcholine (ACh). ACh crosses the synaptic gap and binds to ACh receptors (AChRs) tightly clustered on the surface of the muscle fiber; this leads to the endplate potential which initiates the muscle action potential that results in muscle contraction. This is a simplified version of the events in neuromuscular transmission that take place within milliseconds, and are dependent on a tiny but highly structured NMJ. Much of this review is devoted to describing in more detail the development, maturation, maintenance and regeneration of the NMJ, but first we describe briefly the most important molecules involved and the conditions that affect their numbers and function. Most important clinically worldwide, are myasthenia gravis (MG), the Lambert-Eaton myasthenic syndrome (LEMS) and congenital myasthenic syndromes (CMS), each of which causes specific molecular defects. In addition, we mention the neurotoxins from bacteria, snakes and many other species that interfere with neuromuscular transmission and cause potentially fatal diseases, but have also provided useful probes for investigating neuromuscular transmission. There are also changes in NMJ structure and function in motor neuron disease, spinal muscle atrophy and sarcopenia that are likely to be secondary but might provide treatment targets. The NMJ is one of the best studied and most disease-prone synapses in the nervous system and it is amenable to in vivo and ex vivo investigation and to systemic therapies that can help restore normal function.
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Affiliation(s)
- Pedro M Rodríguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.,Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Judith Cossins
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.,Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.,Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.,Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
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23
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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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24
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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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25
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Fichtner ML, Jiang R, Bourke A, Nowak RJ, O'Connor KC. Autoimmune Pathology in Myasthenia Gravis Disease Subtypes Is Governed by Divergent Mechanisms of Immunopathology. Front Immunol 2020; 11:776. [PMID: 32547535 PMCID: PMC7274207 DOI: 10.3389/fimmu.2020.00776] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 04/06/2020] [Indexed: 12/13/2022] Open
Abstract
Myasthenia gravis (MG) is a prototypical autoantibody mediated disease. The autoantibodies in MG target structures within the neuromuscular junction (NMJ), thus affecting neuromuscular transmission. The major disease subtypes of autoimmune MG are defined by their antigenic target. The most common target of pathogenic autoantibodies in MG is the nicotinic acetylcholine receptor (AChR), followed by muscle-specific kinase (MuSK) and lipoprotein receptor-related protein 4 (LRP4). MG patients present with similar symptoms independent of the underlying subtype of disease, while the immunopathology is remarkably distinct. Here we highlight these distinct immune mechanisms that describe both the B cell- and autoantibody-mediated pathogenesis by comparing AChR and MuSK MG subtypes. In our discussion of the AChR subtype, we focus on the role of long-lived plasma cells in the production of pathogenic autoantibodies, the IgG1 subclass mediated pathology, and contributions of complement. The similarities underlying the immunopathology of AChR MG and neuromyelitis optica (NMO) are highlighted. In contrast, MuSK MG is caused by autoantibody production by short-lived plasmablasts. MuSK MG autoantibodies are mainly of the IgG4 subclass which can undergo Fab-arm exchange (FAE), a process unique to this subclass. In FAE IgG4, molecules can dissociate into two halves and recombine with other half IgG4 molecules resulting in bispecific antibodies. Similarities between MuSK MG and other IgG4-mediated autoimmune diseases, including pemphigus vulgaris (PV) and chronic inflammatory demyelinating polyneuropathy (CIDP), are highlighted. Finally, the immunological distinctions are emphasized through presentation of biological therapeutics that provide clinical benefit depending on the MG disease subtype.
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Affiliation(s)
- Miriam L Fichtner
- Department of Neurology, School of Medicine, Yale University, New Haven, CT, United States.,Department of Immunobiology, School of Medicine, Yale University, New Haven, CT, United States
| | - Ruoyi Jiang
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT, United States
| | - Aoibh Bourke
- Trinity Hall, University of Cambridge, Cambridge, United Kingdom
| | - Richard J Nowak
- Department of Neurology, School of Medicine, Yale University, New Haven, CT, United States
| | - Kevin C O'Connor
- Department of Neurology, School of Medicine, Yale University, New Haven, CT, United States.,Department of Immunobiology, School of Medicine, Yale University, New Haven, CT, United States
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26
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Datta S, Singh S, Govindarajan R. Retrospective Analysis of Eculizumab in Patients with Acetylcholine Receptor Antibody-Negative Myasthenia Gravis: A Case Series. J Neuromuscul Dis 2020; 7:269-277. [PMID: 32444555 PMCID: PMC7369065 DOI: 10.3233/jnd-190464] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Background: The role of the complement cascade in acetylcholine receptor antibody-negative (AChR–) myasthenia gravis (MG) is unclear. Objective: To assess the efficacy and tolerability of eculizumab (terminal complement inhibitor) in patients with AChR–MG. Methods: Retrospective chart review of data from six patients treated for 12 months with eculizumab for treatment-refractory, AChR–(by radioimmunoassay) generalized MG (gMG). The eculizumab dose was 900 mg/week for 4 weeks then 1200 mg every 2 weeks. Outcome measures were Myasthenia Gravis–Activities of Daily Living (MG-ADL) scores, number of exacerbations, and qualitative physical assessments based on selected items of the Quantitative Myasthenia Gravis evaluation (ptosis, double vision, eye closure, duration of ability to stretch out limbs). Results: All patients were female (mean age, 50.8 years). In the 12 months before eculizumab initiation, all measures were relatively stable. After its initiation, clinically meaningful reductions (≥2 points) in total MG-ADL scores were observed before or at 5 months and were maintained to Month 12 in all patients; mean (standard deviation [SD]) scores were 11.3 (0.9) and 5.0 (0.9), respectively. There was also a reduction in the mean (SD) number of exacerbations per patient, from 2.8 (1.2) to 0.3 (0.5) in the 12 months before and after eculizumab initiation, respectively. Physical assessment ratings were improved in all patients. Adverse events were reported in four patients, but all were mild and none were treatment-related. Conclusions: This small retrospective analysis provides preliminary evidence for the efficacy of eculizumab in treatment-refractory gMG that was AChR–according to radioimmunoassay. Larger, more robust studies are warranted to evaluate this further.
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Affiliation(s)
- Sorabh Datta
- University of Missouri Health Care, Columbia, MO, USA
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27
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Lazaridis K, Tzartos SJ. Autoantibody Specificities in Myasthenia Gravis; Implications for Improved Diagnostics and Therapeutics. Front Immunol 2020; 11:212. [PMID: 32117321 PMCID: PMC7033452 DOI: 10.3389/fimmu.2020.00212] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 01/27/2020] [Indexed: 12/13/2022] Open
Abstract
Myasthenia gravis (MG) is an autoimmune disease characterized by muscle weakness and fatiguability of skeletal muscles. It is an antibody-mediated disease, caused by autoantibodies targeting neuromuscular junction proteins. In the majority of patients (~85%) antibodies against the muscle acetylcholine receptor (AChR) are detected, while in 6% antibodies against the muscle-specific kinase (MuSK) are detected. In ~10% of MG patients no autoantibodies can be found with the classical diagnostics for AChR and MuSK antibodies (seronegative MG, SN-MG), making the improvement of methods for the detection of known autoantibodies or the discovery of novel antigenic targets imperative. Over the past years, using cell-based assays or improved highly sensitive immunoprecipitation assays, it has been possible to detect autoantibodies in previously SN-MG patients, including the identification of the low-density lipoprotein receptor-related protein 4 (LRP4) as a third MG autoantigen, as well as AChR and MuSK antibodies undetectable by conventional methods. Furthermore, antibodies against other extracellular or intracellular targets, such as titin, the ryanodine receptor, agrin, collagen Q, Kv1.4 potassium channels and cortactin have been found in some MG patients, which can be useful biomarkers. In addition to the improvement of diagnosis, the identification of the patients' autoantibody specificity is important for their stratification into respective subgroups, which can differ in terms of clinical manifestations, prognosis and most importantly their response to therapies. The knowledge of the autoantibody profile of MG patients would allow for a therapeutic strategy tailored to their MG subgroup. This is becoming especially relevant as there is increasing progress toward the development of antigen-specific therapies, targeting only the specific autoantibodies or immune cells involved in the autoimmune response, such as antigen-specific immunoadsorption, which have shown promising results. We will herein review the advances made by us and others toward development of more sensitive detection methods and the identification of new antibody targets in MG, and discuss their significance in MG diagnosis and therapy. Overall, the development of novel autoantibody assays is aiding in the more accurate diagnosis and classification of MG patients, supporting the development of advanced therapeutics and ultimately the improvement of disease management and patient quality of life.
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Affiliation(s)
| | - Socrates J Tzartos
- Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece.,Tzartos NeuroDiagnostics, Athens, Greece
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28
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Min YG, Park C, Kwon YN, Shin JY, Sung JJ, Hong YH. B Cell Immunophenotyping and Transcriptional Profiles of Memory B Cells in Patients with Myasthenia Gravis. Exp Neurobiol 2019; 28:720-726. [PMID: 31902159 PMCID: PMC6946110 DOI: 10.5607/en.2019.28.6.720] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/17/2019] [Accepted: 12/17/2019] [Indexed: 12/13/2022] Open
Abstract
Myasthenia gravis (MG) is an autoimmune neuromuscular junction disorders mediated by various autoantibodies. Although most patients with MG require chronic immunosuppressive treatment to control disease activity, appropriate surveillance biomarkers that monitor disease activity or potential toxicity of immunosuppressants are yet to be developed. Herein, we investigated quantitative distribution of peripheral blood B cell subsets and transcriptional profiles of memory B cells (CD19+ CD27+) in several subgroups of MG patients classified according to the Myasthenia Gravis Foundation of America (MGFA) Clinical Classification. This study suggests potential immunologic B-cell markers that may guide treatment decision in future clinical settings.
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Affiliation(s)
- Young Gi Min
- Department of Neurology, Seoul National University Hospital, Seoul 03080, Korea
| | - Canaria Park
- Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Council, Seoul 03080, Korea
| | - Young-Nam Kwon
- Department of Neurology, Seoul National University Hospital, Seoul 03080, Korea.,Department of Neurology, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul 07061, Korea
| | - Je-Young Shin
- Department of Neurology, Seoul National University Hospital, Seoul 03080, Korea
| | - Jung-Joon Sung
- Department of Neurology, Seoul National University Hospital, Seoul 03080, Korea.,Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Council, Seoul 03080, Korea
| | - Yoon-Ho Hong
- Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Council, Seoul 03080, Korea.,Department of Neurology, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul 07061, Korea
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29
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Souto EB, Lima B, Campos JR, Martins-Gomes C, Souto SB, Silva AM. Myasthenia gravis: State of the art and new therapeutic strategies. J Neuroimmunol 2019; 337:577080. [PMID: 31670062 DOI: 10.1016/j.jneuroim.2019.577080] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 10/04/2019] [Indexed: 12/11/2022]
Abstract
Myasthenia Gravis (MG) - an autoimmune neuromuscular disease - is known by the production of autoantibodies against components of the neuromuscular junction mainly to the acetylcholine receptor, which cause the destruction and compromises the synaptic transmission. This disease is characterized by fluctuating and fatigable muscle weakness, becoming more intensive with activity, but with an improvement under resting. There are many therapeutic strategies used to alleviate MG symptoms, either by improving the transmission of the nerve impulse or by ameliorating autoimmune reactions with e.g. steroids, immunosuppressant drugs, or monoclonal antibodies (rituximab and eculizumab). Many breakthroughs in the discovery of new therapeutic targets have been reported, but MG remains to be a chronic disease where the symptoms are kept in the majority of patients. In this review, we discuss the different therapeutic strategies that have been used over the years to alleviate MG symptoms, as well as innovative therapeutic approaches currently under study.
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Affiliation(s)
- Eliana B Souto
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, 3000-548 Coimbra, Portugal; CEB - Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
| | - Bernardo Lima
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, 3000-548 Coimbra, Portugal
| | - Joana R Campos
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, 3000-548 Coimbra, Portugal
| | - Carlos Martins-Gomes
- Department of Biology and Environment, School of Life and Environmental Sciences, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal; Centre for the Research and Technology of Agro-Environmental and Biological Sciences, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal
| | - Selma B Souto
- Department of Endocrinology of S. João Hospital, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal
| | - Amélia M Silva
- Department of Biology and Environment, School of Life and Environmental Sciences, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal; Centre for the Research and Technology of Agro-Environmental and Biological Sciences, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal.
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30
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Beecher G, Putko BN, Wagner AN, Siddiqi ZA. Therapies Directed Against B-Cells and Downstream Effectors in Generalized Autoimmune Myasthenia Gravis: Current Status. Drugs 2019; 79:353-364. [PMID: 30762205 DOI: 10.1007/s40265-019-1065-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Myasthenia gravis is a rare, heterogeneous, classical autoimmune disease characterized by fatigable skeletal muscle weakness, which is directly mediated by autoantibodies targeting various components of the neuromuscular junction, including the acetylcholine receptor, muscle specific tyrosine kinase, and lipoprotein-related protein 4. Subgrouping of myasthenia gravis is dependent on the age of onset, pattern of clinical weakness, autoantibody detected, type of thymic pathology, and response to immunotherapy. Generalized immunosuppressive therapies are effective in all subgroups of myasthenia gravis; however, approximately 15% remain refractory and more effective treatments with improved safety profiles are needed. In recent years, successful utilization of targeted B-cell therapies in this disease has triggered renewed focus in unraveling the underlying immunopathology in attempts to identify newer therapeutic targets. While myasthenia gravis is predominantly B-cell mediated, T cells, T cell-B cell interactions, and B-cell-related factors are increasingly recognized to play key roles in its immunopathology, particularly in autoantibody production, and novel therapies have focused on targeting these specific immune system components. This overview describes the current understanding of myasthenia gravis immunopathology before discussing B-cell-related therapies, their therapeutic targets, and the rationale and evidence for their use. Several prospective studies demonstrated efficacy of rituximab in various myasthenia gravis subtypes, particularly that characterized by antibodies against muscle-specific tyrosine kinase. However, a recent randomized control trial in patients with acetylcholine receptor antibodies was negative. Eculizumab, a complement inhibitor, has recently gained regulatory approval for myasthenia gravis based on a phase III trial that narrowly missed its primary endpoint while achieving robust results in all secondary endpoints. Zilucoplan is a subcutaneously administered terminal complement inhibitor that recently demonstrated significant improvements in functional outcome measures in a phase II trial. Rozanolixizumab, CFZ533, belimumab, and bortezomib are B-cell-related therapies that are in the early stages of evaluation in treating myasthenia gravis. The rarity of myasthenia gravis, heterogeneity in its clinical manifestations, and variability in immunosuppressive regimens are challenges to conducting successful trials. Nonetheless, these are promising times for myasthenia gravis, as renewed research efforts provide novel insights into its immunopathology, allowing for development of targeted therapies with increased efficacy and safety.
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Affiliation(s)
- Grayson Beecher
- Division of Neurology, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta Hospital, 7-112 Clinical Sciences Building, 11350-83 Ave, Edmonton, AB, T6G 2G3, Canada
| | - Brendan Nicholas Putko
- Division of Neurology, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta Hospital, 7-112 Clinical Sciences Building, 11350-83 Ave, Edmonton, AB, T6G 2G3, Canada
| | - Amanda Nicole Wagner
- Division of Neurology, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta Hospital, 7-112 Clinical Sciences Building, 11350-83 Ave, Edmonton, AB, T6G 2G3, Canada
| | - Zaeem Azfer Siddiqi
- Division of Neurology, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta Hospital, 7-112 Clinical Sciences Building, 11350-83 Ave, Edmonton, AB, T6G 2G3, Canada.
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31
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Chamberlain JL, Huda S, Whittam DH, Matiello M, Morgan BP, Jacob A. Role of complement and potential of complement inhibitors in myasthenia gravis and neuromyelitis optica spectrum disorders: a brief review. J Neurol 2019; 268:1643-1664. [PMID: 31482201 DOI: 10.1007/s00415-019-09498-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/02/2019] [Accepted: 08/05/2019] [Indexed: 02/08/2023]
Abstract
The complement system is a powerful member of the innate immune system. It is highly adept at protecting against pathogens, but exists in a delicate balance between its protective functions and overactivity, which can result in autoimmune disease. A cascade of complement proteins that requires sequential activation, and numerous complement regulators, exists to regulate a proportionate response to pathogens. In spite of these mechanisms there is significant evidence for involvement of the complement system in driving the pathogenesis of variety of diseases including neuromyelitis optica spectrum disorders (NMOSD) and myasthenia gravis (MG). As an amplification cascade, there are an abundance of molecular targets that could be utilized for therapeutic intervention. Clinical trials assessing complement pathway inhibition in both these conditions have recently been completed and include the first randomized placebo-controlled trial in NMOSD showing positive results. This review aims to review and update the reader on the complement system and the evolution of complement-based therapeutics in these two disorders.
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Affiliation(s)
| | - Saif Huda
- Department of Neurology, The Walton Centre, Lower Lane, Liverpool, L9 7LJ, UK
| | - Daniel H Whittam
- Department of Neurology, The Walton Centre, Lower Lane, Liverpool, L9 7LJ, UK
| | - Marcelo Matiello
- Department of Neurology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114, USA
| | - B Paul Morgan
- School of Medicine, Henry Wellcome Building for Biomedical Research, University Hospital of Wales, Heath Park, Cardiff, CF14 4XN, UK
| | - Anu Jacob
- Department of Neurology, The Walton Centre, Lower Lane, Liverpool, L9 7LJ, UK.,University of Liverpool, Liverpool, UK
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Hehir MK, Silvestri NJ. Generalized Myasthenia Gravis: Classification, Clinical Presentation, Natural History, and Epidemiology. Neurol Clin 2019; 36:253-260. [PMID: 29655448 DOI: 10.1016/j.ncl.2018.01.002] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Myasthenia gravis (MG) is a rare disease, but the most common disorder of the neuromuscular junction. It is the prototypic autoimmune disease most commonly caused by antibodies to the acetylcholine receptor (AChR) leading to characteristic fatigable weakness of the ocular, bulbar, respiratory, axial, and limb muscles. The majority of patients with MG first present with ocular symptoms. Most patients with MG will experience at least 1 exacerbation of symptoms throughout the course of their illness. This article will cover the epidemiology, clinical presentation, classification, and natural history of MG.
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Affiliation(s)
- Michael K Hehir
- Department of Neurosciences, Larner College of Medicine at the University of Vermont, University of Vermont, 1 South Prospect Street, Burlington, VT 05401, USA.
| | - Nicholas J Silvestri
- Department of Neurology, University at Buffalo Jacobs School of Medicine & Biomedical Sciences, 1010 Main Street, Buffalo, New York 14202, USA
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Rivner MH, Pasnoor M, Dimachkie MM, Barohn RJ, Mei L. Muscle-Specific Tyrosine Kinase and Myasthenia Gravis Owing to Other Antibodies. Neurol Clin 2019; 36:293-310. [PMID: 29655451 DOI: 10.1016/j.ncl.2018.01.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Around 20% of patients with myasthenia gravis are acetylcholine receptor antibody negative; muscle-specific tyrosine kinase antibodies (MuSK) were identified as the cause of myasthenia gravis in 30% to 40% of these cases. Anti MuSK myasthenia gravis is associated with specific clinical phenotypes. One is a bulbar form with fewer ocular symptoms. Others show an isolated head drop or symptoms indistinguishable from acetylcholine receptor-positive myasthenia gravis. These patients usually respond well to immunosuppressive therapy, but not as well to cholinesterase inhibitors. Other antibodies associated with myasthenia gravis, including low-density lipoprotein receptor-related protein 4, are discussed.
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Affiliation(s)
- Michael H Rivner
- EMG Lab, Augusta University, 1120 15th Street, BP-4390, Augusta, GA 30912, USA.
| | - Mamatha Pasnoor
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| | - Mazen M Dimachkie
- Department of Neurology, University of Kansas Medical Center, 3599 Rainbow Boulevard, Mail Stop 2012, Kansas City, KS 66103, USA
| | - Richard J Barohn
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Mail Stop 4017, Kansas City, KS 66160, USA
| | - Lin Mei
- Department of Neuroscience and Regenerative Medicine, Augusta University, 1120 15th Street, CA-2014, Augusta, GA 30912, USA
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Abstract
This article discusses antibodies associated with immune-mediated myasthenia gravis and the pathologic action of these antibodies at the neuromuscular junctions of skeletal muscle. To explain how these antibodies act, we consider the physiology of neuromuscular transmission with emphasis on 4 features: the structure of the neuromuscular junction; the roles of postsynaptic acetylcholine receptors and voltage-gated Na+ channels and in converting the chemical signal from the nerve terminal into a propagated action potential on the muscle fiber that triggers muscle contraction; the safety factor for neuromuscular transmission; and how the safety factor is reduced in different forms of autoimmune myasthenia gravis.
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Affiliation(s)
- Robert L Ruff
- Department of Neurology, Case Western University School of Medicine, The Metro Health System, 2500 Metro Health Drive, Cleveland, OH 44109, USA; Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Robert P Lisak
- Department of Neurology, Wayne State University School of Medicine, 8D University Health Center, 4201 St Antoine, Detroit, MI 48201, USA; Department of Biochemistry, Microbiology and Immunology, Wayne State University, Detroit, MI, USA.
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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: 80] [Impact Index Per Article: 16.0] [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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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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Paz ML, Barrantes FJ. Autoimmune Attack of the Neuromuscular Junction in Myasthenia Gravis: Nicotinic Acetylcholine Receptors and Other Targets. ACS Chem Neurosci 2019; 10:2186-2194. [PMID: 30916550 DOI: 10.1021/acschemneuro.9b00041] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The nicotinic acetylcholine receptor (nAChR) family, the archetype member of the pentameric ligand-gated ion channels, is ubiquitously distributed in the central and peripheral nervous systems, and its members are the targets for both genetic and acquired forms of neurological disorders. In the central nervous system, nAChRs contribute to the pathological mechanisms of neurodegenerative disorders, such as Alzheimer and Parkinson diseases. In the peripheral nerve-muscle synapse, the vertebrate neuromuscular junction, "classical" myasthenia gravis (MG) and other forms of neuromuscular transmission disorders are antibody-mediated autoimmune diseases. In MG, antibodies to the nAChR bind to the postsynaptic receptors and activate the classical complement pathway culminating in the formation of the membrane attack complex, with the subsequent destruction of the postsynaptic apparatus. Divalent nAChR-antibodies also cause internalization and loss of the nAChRs. Loss of receptors by either mechanism results in the muscle weakness and fatigability that typify the clinical manifestations of the disease. Other targets for antibodies, in a minority of patients, include muscle specific kinase (MuSK) and low-density lipoprotein related protein 4 (LRP4). This brief Review analyzes the current status of muscle-type nAChR in relation to the pathogenesis of autoimmune diseases affecting the peripheral cholinergic synapse.
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Affiliation(s)
- Mariela L. Paz
- Immunology Department, Faculty of Pharmacy and Biochemistry, IDEHU-CONICET, University of Buenos Aires, Junin 956, C1113AAD Buenos Aires, Argentina
| | - Francisco J. Barrantes
- Laboratory of Molecular Neurobiology, Biomedical Research Institute (BIOMED), UCA-CONICET, Av. Alicia Moreau de Justo 1600, C1107AFF Buenos Aires, Argentina
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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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Cao YL, Dong W, Li YZ, Han W. MicroRNA-653 Inhibits Thymocyte Proliferation and Induces Thymocyte Apoptosis in Mice with Autoimmune Myasthenia Gravis by Downregulating TRIM9. Neuroimmunomodulation 2019; 26:7-18. [PMID: 30703767 DOI: 10.1159/000494802] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 10/23/2018] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES Myasthenia gravis (MG) is an organ-specific autoimmune neuromuscular disorder that occurs as a result of the impairment in neuromuscular junction and autoantibody attack on the postsynaptic receptors. Increasing evidence suggests that microRNAs (miRs) might be involved in the development of MG. Therefore, the present study aimed to investigate the regulatory function of miR-653 on MG and its relationship with tripartite motif 9 (TRIM9). METHODS The thymic tissues obtained from MG patients with thymic hyperplasia were prepared for establishing an MG mouse model in BALB/c mice. Afterwards, the miR-653 and TRIM9 expressions were determined in thymic tissues. A dual-luciferase reporter assay was carried out to validate whether miR-653 directly targets TRIM9. Finally, the thymocytes were exposed to mimics or inhibitors of miR-653, or siRNA against TRIM9 with the use of MTT assays and flow cytometry for the verification of the gain or loss function of miR-653 and TRIM9 on viability, cell cycle progression, and apoptosis of thymocytes. RESULTS There was a decrease in thymocyte miR-653 and an increase in TRIM9 in thymic tissues of MG mice. miR-653 was found to negatively regulate TRIM9. Overexpression of miR-653 or depletion of TRIM9 resulted in the inhibition of cell viability, suppression of cell cycle progression, and induction of apoptosis rate in thymocytes. CONCLUSION The findings from the present study provided evidence that miR-653 impairs proliferation and promotes apoptosis of thymocytes of MG mice by suppressing TRIM9, indicating that miR-653 could be used as potential therapeutic target in the treatment of autoimmune MG.
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Affiliation(s)
- Yu-Ling Cao
- Department of Neurology, Jining No. 1 People's Hospital, Jining, China
| | - Wei Dong
- Department of Emergency, Jining No. 1 People's Hospital, Jining, China,
| | - Yu-Zhi Li
- Department of Neurology, Jining No. 1 People's Hospital, Jining, China
| | - Wei Han
- Department of Neurology, Jining No. 1 People's Hospital, Jining, China
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What is in the Neuromuscular Junction Literature? J Clin Neuromuscul Dis 2018; 20:76-84. [PMID: 30439753 DOI: 10.1097/cnd.0000000000000218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This update begins with myasthenia gravis and the roles of anti-agrin and cortactin antibodies. Regarding diagnosis, a report on repeated ice pack testing is highlighted as are several reports on the close correlation of electrodiagnostic testing with clinical features and the response to treatment. The incidence of head drop and associated clinical and ventilatory features are gleaned from a retrospective study. We also discuss a study that assessed the predominantly symmetric and conjugate ocular findings in MuSK-myasthenia gravis. Other topics that are covered include quality of life and preoperative risk. We then summarize the positive treatment trials of subcutaneous immunoglobulin and eculizumab. Turning to Lambert-Eaton Myasthenic Syndrome, we report on an epidemiologic study performed on the veteran affairs population, the results of the DAPPER study of 3, 4 diaminopyridine, and look to the future for other treatment options involving calcium gating modifiers.
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Asmail A, Kesler A, Kolb H, Drory VE, Karni A. A tri-modal distribution of age-of-onset in female patients with myasthenia gravis is associated with the gender-related clinical differences. Int J Neurosci 2018; 129:313-319. [DOI: 10.1080/00207454.2018.1529669] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Ali Asmail
- Neuroimmunology Service, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Anat Kesler
- Neuro-ophthalmology Unit of the Department of Ophthalmology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Hadar Kolb
- Neuroimmunology Service, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Vivian E. Drory
- The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Neuromuscular Service of the Department of Neurology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Arnon Karni
- Neuroimmunology Service, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Segol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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Wang S, Breskovska I, Gandhy S, Punga AR, Guptill JT, Kaminski HJ. Advances in autoimmune myasthenia gravis management. Expert Rev Neurother 2018; 18:573-588. [PMID: 29932785 PMCID: PMC6289049 DOI: 10.1080/14737175.2018.1491310] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Myasthenia gravis (MG) is an autoimmune neuromuscular disorder with no cure and conventional treatments limited by significant adverse effects and variable benefit. In the last decade, therapeutic development has expanded based on improved understanding of autoimmunity and financial incentives for drug development in rare disease. Clinical subtypes exist based on age, gender, thymic pathology, autoantibody profile, and other poorly defined factors, such as genetics, complicate development of specific therapies. Areas covered: Clinical presentation and pathology vary considerably among patients with some having weakness limited to the ocular muscles and others having profound generalized weakness leading to respiratory insufficiency. MG is an antibody-mediated disorder dependent on autoreactive B cells which require T-cell support. Treatments focus on elimination of circulating autoantibodies or inhibition of effector mechanisms by a broad spectrum of approaches from plasmapheresis to B-cell elimination to complement inhibition. Expert commentary: Standard therapies and those under development are disease modifying and not curative. As a rare disease, clinical trials are challenged in patient recruitment. The great interest in development of treatments specific for MG is welcome, but decisions will need to be made to focus on those that offer significant benefits to patients.
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Affiliation(s)
- Shuhui Wang
- Department of Neurology, George Washington University, Washington DC 20008
| | - Iva Breskovska
- Department of Neurology, George Washington University, Washington DC 20008
| | - Shreya Gandhy
- Department of Neurology, George Washington University, Washington DC 20008
| | - Anna Rostedt Punga
- Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Uppsala, Sweden
| | - Jeffery T. Guptill
- Department of Neurology, Duke University Medical Center, Durham, North Carolina, USA
| | - Henry J. Kaminski
- Department of Neurology, George Washington University, Washington DC 20008
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Fang TK, Yan CJ, Du J. CTLA-4 methylation regulates the pathogenesis of myasthenia gravis and the expression of related cytokines. Medicine (Baltimore) 2018; 97:e0620. [PMID: 29718870 PMCID: PMC6393147 DOI: 10.1097/md.0000000000010620] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Myasthenia gravis (MG) is a progressive autoimmune disease that occurs as a result of the failure of neuromuscular transmission and is characterized by muscle weakness. There has been evidence on the correlations between the genetic predisposition of cytotoxic T lymphocyte and the antigen-4 (CTLA-4) and MG. Thus, the present study was conducted to study is designed to examine the effects of CTLA-4 methylation on the pathogenesis of MG and the expressions of related cytokines. METHODS The CTLA-4 methylation levels in peripheral blood were quantified in 103 samples collected from MG patients and 86 samples from healthy individiuals. The expression of serum-related cytokines as well as the Treg cell ratio were examined so as to define the contributory role of CTLA-4 methylation in MG and to identify the interaction between CTLA-4 methylation and related factors, the expressions of DNA methyltransferase (DNMT)l, DNMT3A and DNMT3B, CTLA-4, AchR-Ab, Titin-Ab, RyR-Ab, IL-2, IL-10, IFN-γ, and TGF-β, activity of P- acetylcholinesterase (AchE) and E-AchE. RESULTS The results indicated that the incidence of CTLA-4 methylation was significantly higher in the control group when compared with the MG group, and CTLA-4 methylation was also found to be associated with the thymus status of MG patients. It was also observed from the experiment data that the expressions of DNMTl, DNMT3A, and DNMT3B, along with the expressions of AchR-Ab, Titin-Ab, RyR-Ab, IL-2, IL-10, IFN-γ and TGF-β, and the activity of P-AchE and E-AchE were all higher in the MG group than in the control group, with a reduction of CTLA-4 expression. Another key finding from this study revealed that methylation interference can lead to the suppression in the expression of AchR-Ab, the activity of E-AchE, the expression of IL-2, IL-10, IFN-γ, and TGF-β and the Treg cell ratio in lymphocytes. CONCLUSION In conclusion, the results obtained from the present study highly indicated that CTLA-4 methylation might play a role in facilitating the occurrence of MG and increasing the expressions of related cytokines through the upregulation of AchR-Ab and E-Ach.
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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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Wang J, Xiao Y, Zhang K, Luo B, Shen C. Introducing Autoimmunity at the Synapse by a Novel Animal Model of Experimental Autoimmune Myasthenia Gravis. Neuroscience 2018; 374:264-270. [PMID: 29421431 DOI: 10.1016/j.neuroscience.2018.01.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 12/22/2017] [Accepted: 01/18/2018] [Indexed: 12/13/2022]
Abstract
The neuromuscular junction (NMJ) is a peripheral synapse between motor neurons and skeletal muscle fibers that controls muscle contraction. The NMJ is the target of various disorders including myasthenia gravis (MG), an autoimmune disease in which auto-antibodies (auto-Abs) attack the synapse, and thus cause muscle weakness in patients. There are multiple auto-Abs in the MG patient sera, but not all the Abs are proven to be pathogenic, which increases the difficulties in clinical diagnoses and treatments. To establish the causative roles of auto-Abs in MG pathogenesis, the experimental autoimmune MG (EAMG) induced by the active immunization of auto-antigens (auto-Ags) or the passive transfer of auto-Abs is required. These models simulate many features of the human disease. To date, there are three kinds of EAMG models reported, of which AChR-EAMG and MuSK-EAMG are well characterized, while the recent LRP4-EAMG is much less studied. Here, we report a current summary of LRP4-EAMG and its pathogenic mechanisms. The features of LRP4-EAMG are more similar to those of AChR-EAMG, indicating a similar clinical treatment for LRP4- and AChR-positive MG patients, compared to MuSK-positive MG patients.
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Affiliation(s)
- Jianwen Wang
- The First Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang, China
| | - Yatao Xiao
- The First Affiliated Hospital, Institute of Translational Medicine, School of Medicine, Zhejiang University, Zhejiang, China
| | - Kejing Zhang
- The First Affiliated Hospital, Institute of Translational Medicine, School of Medicine, Zhejiang University, Zhejiang, China
| | - Benyan Luo
- The First Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang, China.
| | - Chengyong Shen
- The First Affiliated Hospital, Institute of Translational Medicine, School of Medicine, Zhejiang University, Zhejiang, China.
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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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Abstract
PURPOSE OF REVIEW This article discusses the pathogenesis, diagnosis, and management of autoimmune myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS). RECENT FINDINGS Recognition of new antigenic targets and improved diagnostic methods promise to improve the diagnosis of MG, although the clinical phenotypes associated with newer antibodies have not yet been defined. Future therapies might specifically target the aberrant immune response. The apparent increase in the prevalence of MG is not fully explained. Results of a long-awaited trial of thymectomy support the practice of performing a thymectomy under specific conditions. SUMMARY The current treatment options are so effective in most patients with MG or LEMS that in patients with refractory disease the diagnosis should be reconsidered. The management of MG is individualized, and familiarity with mechanisms, adverse effects, and strategies to manage these commonly used treatments improves outcome. Patient education is important. LEMS, frequently associated with an underlying small cell lung cancer, is uncommon, and the mainstay of treatment is symptomatic in most patients.
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Autoantibodies to Low-Density Lipoprotein Receptor-Related Protein 4 in Double Seronegative Myasthenia Gravis: A Systematic Review. Can J Neurol Sci 2017; 45:62-67. [DOI: 10.1017/cjn.2017.253] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AbstractBackground: Myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular junction in which a clinical diagnosis may be confirmed with serological testing. The most common autoantibodies used to support a diagnosis of MG are anti-acetylcholine receptor antibodies and anti-muscle-specific tyrosine kinase antibodies. In cases in which both of these autoantibodies are negative (termed double-seronegative [dSNMG]), other autoantibodies such as low-density lipoprotein receptor-related protein 4 (LRP4) may be used to aid in diagnosis. Methods: We have undertaken a systematic literature review to identify studies that have assessed the frequency of anti-LRP4 antibodies in dSNMG patients and the characteristics of anti-LRP4+ dSNMG patients (epidemiology, clinical features, electromyographic findings, or management). PubMed, EMBASE, Medline, and Scopus were searched on January 14, 2017, using the medical subject headings “myasthenia gravis” and “low-density lipoprotein receptor-related protein 4” or “LRP4.” Results: The initial search identified 367 articles. Fourteen publications met the inclusion criteria. There were ten cross-sectional research studies, three were case series, and one was a case report. The majority of studies were limited by small sample sizes of LRP4+ dSNMG. There has been a wide range of frequencies of anti-LRP4 antibodies detected in different MG patient populations, some involving different laboratory techniques. Conclusions: LRP4+ dSNMG is more likely than LRP4– dSNMG to have a younger onset of disease and occur in females. LRP4+ dSNMG most often is mild in severity and often involves isolated ocular weakness. It typically responds well to pyridostigmine or prednisone.
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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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50
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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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