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Su M, Luo Q, Wu Z, Feng H, Zhou H. Thymoma-associated autoimmune encephalitis with myasthenia gravis: Case series and literature review. CNS Neurosci Ther 2024; 30:e14568. [PMID: 38421083 PMCID: PMC10850820 DOI: 10.1111/cns.14568] [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: 03/31/2023] [Revised: 11/20/2023] [Accepted: 12/02/2023] [Indexed: 03/02/2024] Open
Abstract
OBJECTIVES This comprehensive review aimed to compile cases of patients with thymoma diagnosed with both autoimmune encephalitis (AE) and myasthenia gravis (MG), and describe their clinical characteristics. METHODS Clinical records of 3 AE patients in the first affiliated hospital of Sun Yat-sen University were reviewed. All of them were diagnosed with AE between 1 November 2021 and 1 March 2022, and clinical evidence about thymoma and MG was found. All published case reports were searched for comprehensive literature from January 1990 to June 2022. RESULTS A total of 18 cases diagnosed with thymoma-associated autoimmune encephalitis (TAAE) and thymoma-associated myasthenia gravis (TAMG) were included in this complication, wherein 3 cases were in the first affiliated hospital of Sun Yat-sen University and the other 15 were published case reports. 5/18 patients had alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antibody (AMPAR-Ab) in their serum and cerebrospinal fluid (CSF). All of them had positive anti-acetylcholine receptor antibody (AChR-Ab). And 12/18 patients showed a positive response to thymectomy and immunotherapy. Besides, thymoma recurrences were detected because of AE onset. And the shortest interval between operation and AE onset was 2 years in patients with thymoma recurrence. CONCLUSIONS There was no significant difference in the clinical manifestations between these patients and others with only TAMG or TAAE. TAAE was commonly associated with AMPAR2-Ab. Significantly, AE more commonly heralded thymoma recurrences than MG onset. And the intervals of thymectomy and MG or AE onset had different meanings for thymoma recurrence and prognoses of patients.
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Affiliation(s)
- Miao Su
- Department of NeurologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina
| | - Qiuyan Luo
- Department of NeurologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina
- Department of NeurologyGuangzhou Women and Children's Medical CenterGuangzhouChina
| | - Zichao Wu
- Department of NeurologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina
| | - Huiyu Feng
- Department of NeurologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina
| | - Hongyan Zhou
- Department of NeurologyThe First Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina
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Anti-titin antibodies are associated with myocarditis in patients with myasthenia gravis. J Neurol 2023; 270:1457-1465. [PMID: 36383260 DOI: 10.1007/s00415-022-11485-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 11/08/2022] [Accepted: 11/09/2022] [Indexed: 11/17/2022]
Abstract
BACKGROUND Myasthenia gravis (MG) can affect cardiac muscles with variable presentations. Myocarditis is a rare but potentially serious cardiac manifestation of MG. Although thymomas and anti-titin antibodies have been suggested as risk factors for myocarditis in patients with MG, their independent influence on myocarditis has rarely been assessed. METHODS A retrospective chart review was conducted on 247 patients diagnosed with MG who were tested for anti-titin antibodies. Myocarditis was diagnosed on the basis of the European Society of Cardiology 2013 Task Force criteria for clinically suspected myocarditis. Patients were classified into myocarditis-positive and myocarditis-negative groups. Multivariate analysis was performed to analyze the risk factors for myocarditis. RESULTS Of the 247 patients, 25 (10.1%) were myocarditis-positive and 222 (89.9%) were myocarditis-negative. Anti-titin antibody positivity was higher in the myocarditis-positive group than in the myocarditis-negative group (68.0% vs. 28.4%, p < 0.001). A history of MG crisis was more frequent in the myocarditis-positive group than in the myocarditis-negative group (64.0% vs. 10.4%, p < 0.001). The presence of anti-titin antibodies (odds ratio [OR] 7.906; confidence interval [CI] 2.460-25.401) and MG crisis (OR 24.807; CI 7.476-82.311) was significantly associated with myocarditis. The Cox regression model showed that the anti-titin antibody levels (hazard ratio [HR] 3.639; 95% CI 1.557-8.505) and MG crisis (HR 6.137; 95% CI 2.639-14.272) were significant risk factors for the development of myocarditis. CONCLUSION The presence of anti-titin antibody was associated with myocarditis in patients with MG, whereas thymoma was not. Although rare, early suspicion of myocarditis could be required, especially in patients with MG having anti-titin antibodies.
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Cardiac troponin T and autoimmunity in skeletal muscle aging. GeroScience 2022; 44:2025-2045. [PMID: 35034279 PMCID: PMC9616986 DOI: 10.1007/s11357-022-00513-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 01/05/2022] [Indexed: 01/03/2023] Open
Abstract
Age-related muscle mass and strength decline (sarcopenia) impairs the performance of daily living activities and can lead to mobility disability/limitation in older adults. Biological pathways in muscle that lead to mobility problems have not been fully elucidated. Immunoglobulin G (IgG) infiltration in muscle is a known marker of increased fiber membrane permeability and damage vulnerability, but whether this translates to impaired function is unknown. Here, we report that IgG1 and IgG4 are abundantly present in the skeletal muscle (vastus lateralis) of ~ 50% (11 out of 23) of older adults (> 65 years) examined. Skeletal muscle IgG1 was inversely correlated with physical performance (400 m walk time: r = 0.74, p = 0.005; SPPB score: r = - 0.73, p = 0.006) and muscle strength (r = - 0.6, p = 0.05). In a murine model, IgG was found to be higher in both muscle and blood of older, versus younger, C57BL/6 mice. Older mice with a higher level of muscle IgG had lower motor activity. IgG in mouse muscle co-localized with cardiac troponin T (cTnT) and markers of complement activation and apoptosis/necroptosis. Skeletal muscle-inducible cTnT knockin mice also showed elevated IgG in muscle and an accelerated muscle degeneration and motor activity decline with age. Most importantly, anti-cTnT autoantibodies were detected in the blood of cTnT knockin mice, old mice, and older humans. Our findings suggest a novel cTnT-mediated autoimmune response may be an indicator of sarcopenia.
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Jiao L, Li H, Guo S. Eculizumab treatment for myasthenia gravis subgroups: 2021 update. J Neuroimmunol 2022; 362:577767. [PMID: 34823117 DOI: 10.1016/j.jneuroim.2021.577767] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 11/01/2021] [Accepted: 11/13/2021] [Indexed: 01/21/2023]
Abstract
Eculizumab is a recombinant humanized monoclonal antibody that targets the complement protein C5, inhibiting its cleavage into C5a and C5b and ultimately preventing the formation of C5b-9 membrane attack complex (MACs), thereby protecting the neuromuscular junction from the damage of complement activation. In 2017, eculizumab became the second FDA-approved medication for AchR-positive generalized myasthenia gravis (gMG) patients based on the successful results of a randomized, double-blinded, placebo-controlled, phase 2, phase 3 study (the REGAIN trial) and its open-label extension study. Despite the efficacy of eculizumab in treating AchR antibody-positive refractory gMG was demonstrated in the REGAIN study, there is few information on its efficacy in other subgroup of MG patients including seronegative MG, thymoma-associated MG and MG crisis. This narrative review summarizes current clinical studies of eculizumab in these refractory gMG patients, with a focus on the therapeutic efficacy and tolerability in different subgroup of MG.
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Affiliation(s)
- Li Jiao
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jing Wu Road, Huaiyin District, Jinan 250021, Shandong, China
| | - Honghao Li
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jing Wu Road, Huaiyin District, Jinan 250021, Shandong, China
| | - Shougang Guo
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jing Wu Road, Huaiyin District, Jinan 250021, Shandong, China.
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5
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Liu C, Liu P, Ma M, Yang H, Qi G. Efficacy and safety of double-filtration plasmapheresis treatment of myasthenia gravis: A systematic review and meta-analysis. Medicine (Baltimore) 2021; 100:e25622. [PMID: 33907116 PMCID: PMC8084046 DOI: 10.1097/md.0000000000025622] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 12/09/2020] [Accepted: 04/03/2021] [Indexed: 11/25/2022] Open
Abstract
OBJECTIVES To evaluate the efficacy of double-filtration plasmapheresis (DFPP) treatment of myasthenia gravis (MG) through a systematic review and meta-analysis. METHODS PubMed, Cochrane Library, Embase, China National Knowledge Infrastructure (CNKI), Chinese Scientific Journals Database (VIP), and Wanfang databases were searched for randomized controlled trials (RCTs) and clinical controlled trials (CCTs) on DFPP for MG from database establishment to June 2019. Two researchers independently screened the articles, extracted the data, and cross checked the results. RevMan 5.3 was used for statistical analyses. RESULTS Seven RCTs and 2 CCTs were found comprising 329 patients. The results showed that clinical MG remission rate after DFPP treatment was significantly higher (OR = 4.33; 95% confidence interval [CI], 1.97-9.53; P < .001) and the serum levels of antititin antibody was significantly decreased (standardized mean difference [SMD] = 9.30; 95% CI, 7.51-11.08; P < .001). In addition, the quantitative MG (QMG) score, hospital stay and time to remission of MG symptoms, and acetylcholine receptor antibody (AchRAb) decreased in the DFPP treatment group; however, these outcomes had high heterogeneity among the studies. Only one study has reported on the adverse effects, including hypotension and hematoma. CONCLUSION This meta-analysis suggests that DFPP can be recommended for the short-term mitigation of MG. Because our review was limited by the quantity and quality of the included studies, the above conclusions should be verified by additional high-quality studies.
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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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7
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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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Amano E, Otsu S, Suzuki S, Machida A. Eculizumab improved weakness and taste disorder in thymoma-associated generalized myasthenia gravis with anti-striational antibodies: A case report. eNeurologicalSci 2019; 14:72-73. [PMID: 30705973 PMCID: PMC6348763 DOI: 10.1016/j.ensci.2019.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Accepted: 01/07/2019] [Indexed: 11/26/2022] Open
Affiliation(s)
- Eiichiro Amano
- Department of Neurology, Tsuchiura Kyodo General Hospital, 4-1-1 Otsuno, Tsuchiura-shi, Ibaraki, 300-0028, Japan
| | - Shinichi Otsu
- Department of Neurology, Tsuchiura Kyodo General Hospital, 4-1-1 Otsuno, Tsuchiura-shi, Ibaraki, 300-0028, Japan
| | - Shigeaki Suzuki
- Department of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Akira Machida
- Department of Neurology, Tsuchiura Kyodo General Hospital, 4-1-1 Otsuno, Tsuchiura-shi, Ibaraki, 300-0028, Japan
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9
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Stergiou C, Lazaridis K, Zouvelou V, Tzartos J, Mantegazza R, Antozzi C, Andreetta F, Evoli A, Deymeer F, Saruhan-Direskeneli G, Durmus H, Brenner T, Vaknin A, Berrih-Aknin S, Behin A, Sharshar T, De Baets M, Losen M, Martinez-Martinez P, Kleopa KA, Zamba-Papanicolaou E, Kyriakides T, Kostera-Pruszczyk A, Szczudlik P, Szyluk B, Lavrnic D, Basta I, Peric S, Tallaksen C, Maniaol A, Gilhus NE, Casasnovas Pons C, Pitha J, Jakubíkova M, Hanisch F, Bogomolovas J, Labeit D, Labeit S, Tzartos SJ. Titin antibodies in "seronegative" myasthenia gravis--A new role for an old antigen. J Neuroimmunol 2016; 292:108-15. [PMID: 26943968 DOI: 10.1016/j.jneuroim.2016.01.018] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 01/25/2016] [Indexed: 12/11/2022]
Abstract
Myasthenia gravis (MG) is an autoimmune disease caused by antibodies targeting the neuromuscular junction of skeletal muscles. Triple-seronegative MG (tSN-MG, without detectable AChR, MuSK and LRP4 antibodies), which accounts for ~10% of MG patients, presents a serious gap in MG diagnosis and complicates differential diagnosis of similar disorders. Several AChR antibody positive patients (AChR-MG) also have antibodies against titin, usually detected by ELISA. We have developed a very sensitive radioimmunoprecipitation assay (RIPA) for titin antibodies, by which many previously negative samples were found positive, including several from tSN-MG patients. The validity of the RIPA results was confirmed by western blots. Using this RIPA we screened 667 MG sera from 13 countries; as expected, AChR-MG patients had the highest frequency of titin antibodies (40.9%), while MuSK-MG and LRP4-MG patients were positive in 14.6% and 16.4% respectively. Most importantly, 13.4% (50/372) of the tSN-MG patients were also titin antibody positive. None of the 121 healthy controls or the 90 myopathy patients, and only 3.6% (7/193) of other neurological disease patients were positive. We thus propose that the present titin antibody RIPA is a useful tool for serological MG diagnosis of tSN patients.
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Affiliation(s)
- C Stergiou
- Hellenic Pasteur Institute, Athens, Greece; Tzartos NeuroDiagnostics, Athens, Greece
| | | | - V Zouvelou
- Neurology Department, Aeginition Hospital, Athens, Greece
| | - J Tzartos
- Hellenic Pasteur Institute, Athens, Greece; Tzartos NeuroDiagnostics, Athens, Greece
| | - R Mantegazza
- Neurological Institute "C. Besta", Milano, Italy
| | - C Antozzi
- Neurological Institute "C. Besta", Milano, Italy
| | - F Andreetta
- Neurological Institute "C. Besta", Milano, Italy
| | - A Evoli
- Institute of Neurology, Catholic University, Rome, Italy
| | - F Deymeer
- Istanbul University, Istanbul, Turkey
| | | | - H Durmus
- Istanbul University, Istanbul, Turkey
| | - T Brenner
- Hadassah Hebrew University Medical Center, Jerusalem, Israel
| | - A Vaknin
- Hadassah Hebrew University Medical Center, Jerusalem, Israel
| | | | - A Behin
- UPMC and INSERM, Paris, France
| | - T Sharshar
- Raymond Poincaré Hospital, Garches, France
| | - M De Baets
- School for Mental Health and Neuroscience, Maastricht University, The Netherlands
| | - M Losen
- School for Mental Health and Neuroscience, Maastricht University, The Netherlands
| | - P Martinez-Martinez
- School for Mental Health and Neuroscience, Maastricht University, The Netherlands
| | - K A Kleopa
- The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | | | - T Kyriakides
- The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | | | - P Szczudlik
- Department of Neurology, Medical University of Warsaw, Poland
| | - B Szyluk
- Department of Neurology, Medical University of Warsaw, Poland
| | - D Lavrnic
- Neurology Clinic, Clinical Center of Serbia, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - I Basta
- Neurology Clinic, Clinical Center of Serbia, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - S Peric
- Neurology Clinic, Clinical Center of Serbia, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - C Tallaksen
- Norway Department of Neurology, Ullevaal University Hospital, Oslo, Norway; Faculty of Medicine, Olso University, Norway
| | - A Maniaol
- Norway Department of Neurology, Ullevaal University Hospital, Oslo, Norway
| | - N E Gilhus
- Department of Clinical Medicine, University of Bergen, Norway
| | | | - J Pitha
- Department of Neurology and Clinical Neuroscience Center, 1st Faculty of Medicine, Charles University and General Teaching Hospital, Prague, Czech Republic
| | - M Jakubíkova
- Department of Neurology and Clinical Neuroscience Center, 1st Faculty of Medicine, Charles University and General Teaching Hospital, Prague, Czech Republic
| | - F Hanisch
- Universitätsklinikum Halle, Halle, Germany
| | - J Bogomolovas
- Faculty of Clinical Medicine Manheim, University of Heidelberg, Germany
| | - D Labeit
- Faculty of Clinical Medicine Manheim, University of Heidelberg, Germany; Myomedix GmbH, 69151 Neckargemuend, Germany
| | - S Labeit
- Faculty of Clinical Medicine Manheim, University of Heidelberg, Germany
| | - S J Tzartos
- Hellenic Pasteur Institute, Athens, Greece; Tzartos NeuroDiagnostics, Athens, Greece.
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Meriggioli MN, Sanders DB. Muscle autoantibodies in myasthenia gravis: beyond diagnosis? Expert Rev Clin Immunol 2012; 8:427-38. [PMID: 22882218 DOI: 10.1586/eci.12.34] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Myasthenia gravis is an autoimmune disorder of the neuromuscular junction. A number of molecules, including ion channels and other proteins at the neuromuscular junction, may be targeted by autoantibodies leading to abnormal neuromuscular transmission. In approximately 85% of patients, autoantibodies, directed against the postsynaptic nicotinic acetylcholine receptor can be detected in the serum and confirm the diagnosis, but in general, do not precisely predict the degree of weakness or response to therapy. Antibodies to the muscle-specific tyrosine kinase are detected in approximately 50% of generalized myasthenia gravis patients who are seronegative for anti-acetylcholine receptor antibodies, and levels of anti-muscle-specific tyrosine kinase antibodies do appear to correlate with disease severity and treatment response. Antibodies to other muscle antigens may be found in the subsets of myasthenia gravis patients, potentially providing clinically useful diagnostic information, but their utility as relevant biomarkers (measures of disease state or response to treatment) is currently unclear.
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Affiliation(s)
- Matthew N Meriggioli
- Department of Neurology and Rehabilitation, College of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, IL 60612, USA.
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11
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Canalopathies auto-immunes. Rev Med Interne 2011; 32:742-50. [DOI: 10.1016/j.revmed.2011.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Revised: 02/24/2011] [Accepted: 04/09/2011] [Indexed: 01/18/2023]
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12
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Liu Y, Wang W, Li J. Evaluation of Serum IgG Subclass Concentrations in Myasthenia Gravis Patients. Int J Neurosci 2011; 121:570-4. [DOI: 10.3109/00207454.2011.596293] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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13
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Suzuki S, Utsugisawa K, Nagane Y, Suzuki N. Three types of striational antibodies in myasthenia gravis. Autoimmune Dis 2011; 2011:740583. [PMID: 21785709 PMCID: PMC3139883 DOI: 10.4061/2011/740583] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 06/03/2011] [Indexed: 11/20/2022] Open
Abstract
Myasthenia gravis (MG) is caused by antibodies that react mainly with the acetylcholine receptor on the postsynaptic site of the neuromuscular junction. A wide range of clinical presentations and associated features allow MG to be classified into subtypes based on autoantibody status. Striational antibodies, which react with epitopes on the muscle proteins titin, ryanodine receptor (RyR), and Kv1.4, are frequently found in MG patients with late-onset and thymoma. Antititin and anti-RyR antibodies are determined by enzyme-linked immunosorbent assay or immunoblot. More recently, a method for the detection of anti-Kv1.4 autoantibodies has become available, involving 12-15% of all MG patients. The presence of striational antibodies is associated with more severe disease in all MG subgroups. Anti-Kv1.4 antibody is a useful marker for the potential development of lethal autoimmune myocarditis and response to calcineurin inhibitors. Detection of striational antibodies provides more specific and useful clinical information in MG patients.
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Affiliation(s)
- Shigeaki Suzuki
- Department of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Kimiaki Utsugisawa
- Department of Neurology, Hanamaki General Hospital, Hanamaki 025-0075, Japan
| | - Yuriko Nagane
- Department of Neurology, Hanamaki General Hospital, Hanamaki 025-0075, Japan
| | - Norihiro Suzuki
- Department of Neurology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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14
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Vrolix K, Fraussen J, Molenaar PC, Losen M, Somers V, Stinissen P, De Baets MH, Martínez-Martínez P. The auto-antigen repertoire in myasthenia gravis. Autoimmunity 2010; 43:380-400. [PMID: 20380581 DOI: 10.3109/08916930903518073] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Myasthenia Gravis (MG) is an antibody-mediated autoimmune disorder affecting the postsynaptic membrane of the neuromuscular junction (NMJ). MG is characterized by an impaired signal transmission between the motor neuron and the skeletal muscle cell, caused by auto-antibodies directed against NMJ proteins. The auto-antibodies target the nicotinic acetylcholine receptor (nAChR) in about 90% of MG patients. In approximately 5% of MG patients, the muscle specific kinase (MuSK) is the auto-antigen. In the remaining 5% of MG patients, however, antibodies against the nAChR or MuSK are not detectable (idiopathic MG, iMG). Although only the anti-nAChR and anti-MuSK auto-antibodies have been demonstrated to be pathogenic, several other antibodies recognizing self-antigens can also be found in MG patients. Various auto-antibodies associated with thymic abnormalities have been reported, as well as many non-MG-specific auto-antibodies. However, their contribution to the cause, pathology and severity of the disease is still poorly understood. Here, we comprehensively review the reported auto-antibodies in MG patients and discuss their role in the pathology of this autoimmune disease.
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Affiliation(s)
- Kathleen Vrolix
- Division of Neuroscience, School of Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands
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15
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Kusner LL, Kaminski HJ, Soltys J. Effect of complement and its regulation on myasthenia gravis pathogenesis. Expert Rev Clin Immunol 2010; 4:43-52. [PMID: 20477586 DOI: 10.1586/1744666x.4.1.43] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Myasthenia gravis (MG) is primarily caused by antibodies directed towards the skeletal muscle acetylcholine receptor, leading to muscle weakness. Although these antibodies may induce compromise of neuromuscular transmission by blocking acetylcholine receptor function or antigenic modulation, the predominant mechanism of injury to the neuromuscular junction is complement-mediated lysis of the postsynaptic membrane. The vast majority of data to support the role of complement derives from experimentally acquired MG (EAMG). In this article, we review studies that demonstrate the central role of complement in EAMG and MG pathogenesis along with the emerging role of complement in T- and B-cell function, as well as the potential for complement inhibitor-based therapy to treat human MG.
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Affiliation(s)
- Linda L Kusner
- Department of Neurology & Psychiatry, Saint Louis University, 1438 South Grand Blvd, St Louis, MO 63104, USA.
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Liu JF, Wang WX, Xue J, Zhao CB, You HZ, Lu JH, Gu Y. Comparing the Autoantibody Levels and Clinical Efficacy of Double Filtration Plasmapheresis, Immunoadsorption, and Intravenous Immunoglobulin for the Treatment of Late-onset Myasthenia Gravis. Ther Apher Dial 2010; 14:153-60. [DOI: 10.1111/j.1744-9987.2009.00751.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Aarli JA, Gilhus NE, Romi F, Skeie GO. Titin and ryanodine receptor antibodies and neuromuscular involvement in myasthenia gravis. FUTURE NEUROLOGY 2008. [DOI: 10.2217/14796708.3.1.87] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Of sera of patients with myasthenia gravis (MG), 30% contains titin and ryanodine receptor (RyR) antibodies. In early-onset MG (i.e., before 50 years of age), the presence of titin antibodies strongly suggests a thymoma. Late-onset MG comprises one MG group, characterized by a broad antimuscle immune response, including both titin and the acetylcholine receptor (AChR). Another group is preferentially associated with the HLA-A3, B7 and DRw2 antigens, representing a delayed early-onset of the disease that has a selective AChR immune response. The presence of titin and RyR antibodies is associated with more severe disease. Titin antibodies may, in some patients with rippling muscle disease, affect the contractile machinery of myofibers, thereby affecting their mechanical sensitivity. It is not known whether this occurs in MG. RyR antibodies may impair excitation–contraction coupling and contribute to muscle weakness in MG patients. Titin antibodies may serve as tumor markers in early-onset MG patients.
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Affiliation(s)
- Johan A Aarli
- University of Bergen, Department of Clinical Medicine, 5021 Bergen, Norway
| | - Nils Erik Gilhus
- University of Bergen, Department of Clinical Medicine, and, Department of Neurology, Haukeland University Hospital, 5021 Bergen, Norway
| | - Fredrik Romi
- Haukeland University Hospital, Department of Neurology, 5021 Bergen, Norway
| | - Geir Olve Skeie
- University of Bergen, Department of Clinical Medicine, and, Department of Neurology, Haukeland University Hospital, 5021 Bergen, Norway
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Chan KH, Cheung RTF, Mak W, Ho SL. Nonthymoma early-onset- and late-onset-generalized myasthenia gravis—A retrospective hospital-based study. Clin Neurol Neurosurg 2007; 109:686-91. [PMID: 17644246 DOI: 10.1016/j.clineuro.2007.05.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Revised: 05/28/2007] [Accepted: 05/30/2007] [Indexed: 11/20/2022]
Abstract
OBJECTIVE Acquired myasthenia gravis (MG) is predominantly due to nicotinic acetylcholine receptor (AChR) autoantibodies (Ab). Differences between nonthymoma early-onset and late-onset MG were reported. We studied the clinical and serological characteristics of nonthymoma AChR Ab-positive-generalized MG patients. PATIENTS AND METHODS Chinese AChR Ab-positive-generalized MG patients who had generalized disease for 3 years or longer were studied. RESULTS Among 41 such patients, 25 (61%) were female. The mean onset age was 43.5 years (range 9-78 years) and the mean follow-up duration was 7.8 years (range 3-20 years). Sixteen (39%) patients had late-onset disease (onset age >or=50 years). Compared to early-onset patients (onset age <50 years), late-onset patients were characterized by male predominance (p=0.002), absence of thymic lymphofollicular hyperplasia (p=0.036), and a higher striated muscle Ab seropositivity rate (94% versus 4%, p<0.001). Although there was no statistically significant difference in clinical severity and outcome or response to treatment between late-onset and early-onset patients, 50% and 75% of late-onset patients had moderate or severe disease at onset and worst status, respectively, compared to 28% and 52% for early-onset patients at onset and worst status, respectively. Also 63% of late-onset patients had disease progressed within first 3 years compared to only 40% of early-onset patients did. CONCLUSION Nonthymoma late-onset-generalized MG patients were common among Hong Kong Chinese, with a statistically non-significant trend that it was clinically more severe than early-onset MG but with similar clinical outcome or response to treatment; >90% of these patients were seropositive for striated muscle Ab.
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Affiliation(s)
- K H Chan
- Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China.
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Romi F, Kristoffersen EK, Aarli JA, Gilhus NE. The role of complement in myasthenia gravis: serological evidence of complement consumption in vivo. J Neuroimmunol 2005; 158:191-4. [PMID: 15589053 DOI: 10.1016/j.jneuroim.2004.08.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Revised: 08/05/2004] [Accepted: 08/05/2004] [Indexed: 12/01/2022]
Abstract
BACKGROUND Antibodies to the acetylcholine receptor (AChR) titin and the ryanodine receptor (RyR) occur in myasthenia gravis (MG). These antibodies are capable of complement activation in vitro. The involvement of the complement system should cause consumption of complement components such as C3 and C4 in vivo. MATERIALS AND METHODS Complement components C3 and C4 were assayed in sera from 78 AChR antibody-positive MG patients and 52 healthy controls. Forty-eight of the patient sera contained titin antibodies as well, and 20 were also RyR antibody-positive. RESULTS MG patients with AChR antibody concentrations above the median (11.2 nmol/l) had significantly lower mean C3 and C4 concentrations in serum compared to those with AChR antibody concentrations below the median. Titin antibody-positive MG patients, titin antibody-negative early-onset MG patients, titin antibody-negative late-onset MG patients, and controls had similar C3 and C4 concentrations. Nor did mean C3 and C4 concentrations differ in MG patients with RyR antibodies. Patients with severe MG (grades 4 and 5) had similar C3 and similar C4 levels compared to those with mild MG (grades 1 and 2). CONCLUSION An increased in vivo complement consumption was detected in MG patients with high AChR antibody concentrations, unrelated to MG severity and non-AChR muscle antibodies.
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Affiliation(s)
- Fredrik Romi
- Department of Neurology, Haukeland University Hospital, Bergen N-5021, Norway.
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Skeie GO, Romi F, Aarli JA, Bentsen PT, Gilhus NE. Pathogenesis of myositis and myasthenia associated with titin and ryanodine receptor antibodies. Ann N Y Acad Sci 2003; 998:343-50. [PMID: 14592894 DOI: 10.1196/annals.1254.039] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Some myasthenia gravis (MG) patients have antibodies against skeletal muscle antigens in addition to the acetylcholine receptor (AChR). Two major antigens for these antibodies are the Ca(2+) release channel of the sarcoplasmic reticulum, the ryanodine receptor (RyR), and titin, a gigantic filamentous muscle protein essential for muscle structure, function, and development. RyR and titin antibodies are found in MG patients with a thymoma and in a proportion of late-onset MG, and they correlate with severe MG disease. The RyR antibodies recognize a region near the N-terminus important for channel regulation. They inhibit Ca(2+) release from sarcoplasmic reticulum in vitro. There is electrophysiological evidence for a disordered excitation-contraction coupling in MG patients. The presence of titin antibodies, which bind to key regions near the A/I junction and in the central I-band, correlates with myopathy in MG patients. However, so far, there is no direct evidence that antibodies against the intracellular antigens RyR and titin are pathogenic in vivo.
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Affiliation(s)
- Geir Olve Skeie
- Department of Neurology, University of Bergen, Bergen, Norway.
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Abstract
The act of breathing depends on coordinated activity of the respiratory muscles to generate subatmospheric pressure. This action is compromised by disease states affecting anatomical sites ranging from the cerebral cortex to the alveolar sac. Weakness of the respiratory muscles can dominate the clinical manifestations in the later stages of several primary neurologic and neuromuscular disorders in a manner unique to each disease state. Structural abnormalities of the thoracic cage, such as scoliosis or flail chest, interfere with the action of the respiratory muscles-again in a manner unique to each disease state. The hyperinflation that accompanies diseases of the airways interferes with the ability of the respiratory muscles to generate subatmospheric pressure and it increases the load on the respiratory muscles. Impaired respiratory muscle function is the most severe consequence of several newly described syndromes affecting critically ill patients. Research on the respiratory muscles embraces techniques of molecular biology, integrative physiology, and controlled clinical trials. A detailed understanding of disease states affecting the respiratory muscles is necessary for every physician who practices pulmonary medicine or critical care medicine.
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Affiliation(s)
- Franco Laghi
- Division of Pulmonary and Critical Care Medicine, Edward Hines, Jr. VA Hospital, 111 N. 5th Avenue and Roosevelt Road, Hines, IL 60141, USA.
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Abstract
Myasthenia gravis is an autoimmune disease associated with antibodies directed to the postsynaptic acetylcholine receptor. These antibodies reduce the number of receptors. Autoantibodies against AChR and other muscle antigens can be used for the diagnosis of myasthenia gravis and related disorders. The origin and the role of these antibodies in the disease are discussed. Experimental autoimmune myasthenia gravis, an experimental model closely mimicking the disease, has provided answers to many questions about the role of antibodies, complement macrophages and AChR anchor proteins. Genetically modified anti-AChR antibodies may also be used in the future to treat myasthenia.
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Affiliation(s)
- M De Baets
- Department of Neurology, University Hospital Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
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Romi F, Bø L, Skeie GO, Myking A, Aarli JA, Gilhus NE. Titin and ryanodine receptor epitopes are expressed in cortical thymoma along with costimulatory molecules. J Neuroimmunol 2002; 128:82-9. [PMID: 12098514 DOI: 10.1016/s0165-5728(02)00145-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Cortical-type thymomas are associated with myasthenia gravis (MG) in 50% of the cases. MG is caused by antibodies against the acetylcholine receptors (AChR), but additional non-AChR muscle autoantibodies such as those against titin and ryanodine receptor (RyR) are found in up to 95% of MG patients with thymoma. To elucidate the induction of non-AChR autoantibodies in thymoma-associated MG, we studied cortical-type thymomas from seven thymoma MG patients, and sera from six of them. All six had titin antibodies, and four had RyR antibodies. Titin and RyR epitopes were co-expressed along with LFA3 and B7 (BB1) costimulatory molecules on thymoma antigen-presenting cells (APC) in all thymomas. In normal thymus, the staining by anti-titin, anti-RyR, anti-LFA3, and anti-BB1 antibodies was weak and occurred exclusively in the medulla and perivascularly. Our results indicate a primary autosensitization against titin and RyR antigens inside the thymoma. In MG-associated thymoma, the mechanisms involved in the initial autosensitization against titin and RyR are probably similar to those implicated in the autosensitization against AChR. In all cases, there is an overexpression of muscle-like epitopes and costimulatory molecules indicating that the T-cell autoimmunization is actively promoted by the pathogenic microenvironment inside the thymoma.
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Affiliation(s)
- Fredrik Romi
- Department of Neurology, Haukeland University Hospital, 5021, Bergen, Norway.
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Romi F, Gilhus NE, Varhaug JE, Myking A, Skeie GO, Aarli JA. Thymectomy and anti-muscle autoantibodies in late-onset myasthenia gravis. Eur J Neurol 2002; 9:55-61. [PMID: 11784377 DOI: 10.1046/j.1468-1331.2002.00352.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Thymectomy is still widely carried out in myasthenia gravis (MG) patients, but its role, especially in late-onset MG patients, is not established. These patients are immunologically heterogeneous, some with thymoma-like and others with early onset-like features. We evaluated whether any therapeutic effects of thymectomy correlate with the presence of non-acetylcholine receptor (AChR) muscle antibodies. The severity of MG, and titin and ryanodine receptor (RyR) antibodies, were assessed yearly starting from MG onset in 21 thymectomized and 22 non-thymectomized AChR antibody positive late-onset MG patients, who were followed for 2, 3 and 5 years. Clinical or pharmacological remission were seen in six of 11 titin antibody negative but none of the 10 titin antibody positive thymectomized patients, however, the non-thymectomized cases showed an opposite trend. The three MG-related deaths were all in patients with titin antibodies. There was no significant difference in MG severity between thymectomized and non-thymectomized patients; 2 years after MG onset, both groups were significantly improved. This study showed no dramatic benefit from thymectomy in late-onset MG in general. Any limited improvement appeared less likely in cases with titin and/or RyR antibodies.
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Affiliation(s)
- F Romi
- Department of Neurology, Haukeland University Hospital, Bergen, Norway.
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Abstract
This review focuses on the diagnostic tests that may help to confirm myasthenia in patients without acetylcholine receptor antibodies, including the newly discovered anti-muscle-specific receptor tyrosine kinase antibody and other investigations. We discuss management dilemmas, particularly those that revolve around treatments whose efficacy is questionable or unproved, such as thymectomy. We review the important issue of how treatments are assessed, and examine future treatment trial designs.
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Affiliation(s)
- J Palace
- University Department of Clinical Neurology, Radcliffe Infirmary, Oxford, UK
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