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Luong K, Lozier BK, Novis CL, Smith TL, Zuromski LM, Peterson LK. Comparison of three methods for the detection of antibodies against muscle-specific kinase. J Immunol Methods 2024; 526:113627. [PMID: 38311009 DOI: 10.1016/j.jim.2024.113627] [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: 11/01/2023] [Revised: 02/01/2024] [Accepted: 02/01/2024] [Indexed: 02/06/2024]
Abstract
OBJECTIVES To compare 3 different methods for the detection of antibodies against muscle-specific kinase (MuSK). METHODS MuSK antibody testing was performed in 237 serum samples by enzyme-linked immunosorbent assay (ELISA) and fixed cell-based assay (f-CBA-IFA). One hundred and forty-eight (148) of the sera had previously been tested by RIA during clinical testing: 47 MuSK antibody positive and 101 MuSK antibody negative. Of the MuSK RIA negative antibodies, 46 tested positive for other neural antibodies. Additionally, 89 sera were subsequently tested by all three methods: 70 healthy controls and 19 sera positive for other neural antibodies. RESULTS Qualitative inter-assay agreement based on tiered RIA values was 100% for results of 1.00 nmol/L or greater by both methods; 81% and 94% for results between 0.21 and 0.99 nmol/L by ELISA and f-CBA-IFA, respectively; and 0% for results of 0.04-0.20 nmol/L by both methods. Negative results showed 100% agreement between RIA and both ELISA and f-CBA-IFA (n = 55). None of the controls positive for other neural autoantibodies or healthy controls were positive in any assay. CONCLUSION Overall, excellent agreement was observed between the 3 methods used to detect antibodies against MuSK. Both the f-CBA-IFA and ELISA performed comparably to RIA and exhibited excellent overall accuracy for MuSK IgG detection, with the f-CBA-IFA demonstrating higher agreement between positive samples with the RIA than the ELISA without identifying false positives in the control samples. Advantages of non-radioactive methods for the detection of MuSK antibodies include reduced handling and disposal of hazardous materials, potential for automation and the reagents having a longer shelf-life, reducing costs associated with both workflow and lot validations. Thus, commercially available ELISA and transfected cell-based assays are viable alternatives to the traditional radioactive assay used for serologic determination of MuSK IgG.
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Affiliation(s)
- Kyphuong Luong
- ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108, USA
| | - Bucky K Lozier
- ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108, USA
| | - Camille L Novis
- ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108, USA
| | - Tammy L Smith
- ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108, USA; Department of Pathology, University of Utah School of Medicine, 15 N Medical Dr. East Ste. 1100, Salt Lake City, UT 84112, USA; Geriatric Research Education and Clinical Center, George E. Whalen Department of Veterans Affairs Medical Center, Salt Lake City, UT 84148, USA; Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT 84132, USA; Neurology Service, George E. Whalen Department of Veterans Affairs Medical Center, Salt Lake City, UT 84148, USA
| | - Lauren M Zuromski
- ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108, USA
| | - Lisa K Peterson
- ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108, USA; Department of Pathology, University of Utah School of Medicine, 15 N Medical Dr. East Ste. 1100, Salt Lake City, UT 84112, USA.
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2
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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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3
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Villalta D, Fabris M, Verriello L, Grizzo F, Mobilia EM, Lechiara A, Pesce G. Acetylcholine receptor and muscle-specific tyrosine kinase antibodies detection: is it time for a change? Clin Chem Lab Med 2023; 61:e189-e191. [PMID: 37013597 DOI: 10.1515/cclm-2023-0205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 03/27/2023] [Indexed: 04/05/2023]
Affiliation(s)
- Danilo Villalta
- Immunology and Allergy Unit, S. Maria degli Angeli Hospital, Pordenone, Italy
| | - Martina Fabris
- Institute of Clinical Pathology, Santa Maria della Misericordia University Hospital, Udine, Italy
| | - Lorenzo Verriello
- Neurology Unit, Santa Maria della Misericordia University Hospital, Udine, Italy
| | - Francesca Grizzo
- Immunology and Allergy Unit, S. Maria degli Angeli Hospital, Pordenone, Italy
| | | | - Anastasia Lechiara
- Autoimmunity Laboratory, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Giampaola Pesce
- Autoimmunity Laboratory, IRCCS Ospedale Policlinico San Martino, Genova, Italy
- Autoimmunity Laboratory, Department of internal Medicine and Specialties (DiMI), University of Genova, Genova, Italy
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4
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Oh S, Mao X, Manfredo-Vieira S, Lee J, Patel D, Choi EJ, Alvarado A, Cottman-Thomas E, Maseda D, Tsao PY, Ellebrecht CT, Khella SL, Richman DP, O'Connor KC, Herzberg U, Binder GK, Milone MC, Basu S, Payne AS. Precision targeting of autoantigen-specific B cells in muscle-specific tyrosine kinase myasthenia gravis with chimeric autoantibody receptor T cells. Nat Biotechnol 2023; 41:1229-1238. [PMID: 36658341 PMCID: PMC10354218 DOI: 10.1038/s41587-022-01637-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 12/08/2022] [Indexed: 01/21/2023]
Abstract
Muscle-specific tyrosine kinase myasthenia gravis (MuSK MG) is an autoimmune disease that causes life-threatening muscle weakness due to anti-MuSK autoantibodies that disrupt neuromuscular junction signaling. To avoid chronic immunosuppression from current therapies, we engineered T cells to express a MuSK chimeric autoantibody receptor with CD137-CD3ζ signaling domains (MuSK-CAART) for precision targeting of B cells expressing anti-MuSK autoantibodies. MuSK-CAART demonstrated similar efficacy as anti-CD19 chimeric antigen receptor T cells for depletion of anti-MuSK B cells and retained cytolytic activity in the presence of soluble anti-MuSK antibodies. In an experimental autoimmune MG mouse model, MuSK-CAART reduced anti-MuSK IgG without decreasing B cells or total IgG levels, reflecting MuSK-specific B cell depletion. Specific off-target interactions of MuSK-CAART were not identified in vivo, in primary human cell screens or by high-throughput human membrane proteome array. These data contributed to an investigational new drug application and phase 1 clinical study design for MuSK-CAART for the treatment of MuSK autoantibody-positive MG.
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Affiliation(s)
- Sangwook Oh
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Xuming Mao
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Silvio Manfredo-Vieira
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | | | - Eun Jung Choi
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | | | - Damian Maseda
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Patricia Y Tsao
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Christoph T Ellebrecht
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sami L Khella
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David P Richman
- Department of Neurology, University of California - Davis, Davis, CA, USA
| | - Kevin C O'Connor
- Departments of Neurology and Immunobiology, Yale School of Medicine, New Haven, CT, USA
| | | | | | - Michael C Milone
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Aimee S Payne
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Vakrakou AG, Karachaliou E, Chroni E, Zouvelou V, Tzanetakos D, Salakou S, Papadopoulou M, Tzartos S, Voumvourakis K, Kilidireas C, Giannopoulos S, Tsivgoulis G, Tzartos J. Immunotherapies in MuSK-positive Myasthenia Gravis; an IgG4 antibody-mediated disease. Front Immunol 2023; 14:1212757. [PMID: 37564637 PMCID: PMC10410455 DOI: 10.3389/fimmu.2023.1212757] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 07/05/2023] [Indexed: 08/12/2023] Open
Abstract
Muscle-specific kinase (MuSK) Myasthenia Gravis (MG) represents a prototypical antibody-mediated disease characterized by predominantly focal muscle weakness (neck, facial, and bulbar muscles) and fatigability. The pathogenic antibodies mostly belong to the immunoglobulin subclass (Ig)G4, a feature which attributes them their specific properties and pathogenic profile. On the other hand, acetylcholine receptor (AChR) MG, the most prevalent form of MG, is characterized by immunoglobulin (Ig)G1 and IgG3 antibodies to the AChR. IgG4 class autoantibodies are impotent to fix complement and only weakly bind Fc-receptors expressed on immune cells and exert their pathogenicity via interfering with the interaction between their targets and binding partners (e.g. between MuSK and LRP4). Cardinal differences between AChR and MuSK-MG are the thymus involvement (not prominent in MuSK-MG), the distinct HLA alleles, and core immunopathological patterns of pathology in neuromuscular junction, structure, and function. In MuSK-MG, classical treatment options are usually less effective (e.g. IVIG) with the need for prolonged and high doses of steroids difficult to be tapered to control symptoms. Exceptional clinical response to plasmapheresis and rituximab has been particularly observed in these patients. Reduction of antibody titers follows the clinical efficacy of anti-CD20 therapies, a feature implying the role of short-lived plasma cells (SLPB) in autoantibody production. Novel therapeutic monoclonal against B cells at different stages of their maturation (like plasmablasts), or against molecules involved in B cell activation, represent promising therapeutic targets. A revolution in autoantibody-mediated diseases is pharmacological interference with the neonatal Fc receptor, leading to a rapid reduction of circulating IgGs (including autoantibodies), an approach already suitable for AChR-MG and promising for MuSK-MG. New precision medicine approaches involve Chimeric autoantibody receptor T (CAAR-T) cells that are engineered to target antigen-specific B cells in MuSK-MG and represent a milestone in the development of targeted immunotherapies. This review aims to provide a detailed update on the pathomechanisms involved in MuSK-MG (cellular and humoral aberrations), fostering the understanding of the latest indications regarding the efficacy of different treatment strategies.
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Affiliation(s)
- Aigli G. Vakrakou
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Eleni Karachaliou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Elisabeth Chroni
- Department of Neurology, School of Medicine, University of Patras, Patras, Greece
| | - Vasiliki Zouvelou
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Dimitrios Tzanetakos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Stavroula Salakou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Marianna Papadopoulou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
- Department of Physiotherapy, University of West Attica, Athens, Greece
| | - Socrates Tzartos
- Tzartos NeuroDiagnostics, Athens, Greece
- Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
- Department of Pharmacy, University of Patras, Patras, Greece
| | - Konstantinos Voumvourakis
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Constantinos Kilidireas
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
- Department of Neurology, Henry Dunant Hospital Center, Athens, Greece
| | - Sotirios Giannopoulos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Georgios Tsivgoulis
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
- Department of Neurology, The University of Tennessee Health Science Center, Memphis, TN, United States
| | - John Tzartos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
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Gambino CM, Agnello L, Ciaccio AM, Scazzone C, Vidali M, Di Stefano V, Milano S, Brighina F, Candore G, Lo Sasso B, Ciaccio M. Detection of Antibodies against the Acetylcholine Receptor in Patients with Myasthenia Gravis: A Comparison of Two Enzyme Immunoassays and a Fixed Cell-Based Assay. J Clin Med 2023; 12:4781. [PMID: 37510896 PMCID: PMC10381261 DOI: 10.3390/jcm12144781] [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: 05/11/2023] [Revised: 06/28/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
The detection of serum anti-acetylcholine receptor (AChR) antibodies is currently an important tool for diagnosing myasthenia gravis (MG) since they are present in about 85% of MG patients. Many serological tests are now available. Nevertheless, results from these tests can be different in some patients. The aim of this study is to compare the sensitivity of a commercially available fixed cell-based assay (F-CBA) to that of enzyme-linked immunosorbent assay (ELISA) kits for anti-AChR detection in patients with a diagnosis of MG. Overall, 143 patients with a confirmed MG diagnosis were included in the study. The detection and measurement of serum anti-AChR antibodies were performed by three analytical methods, namely, a competitive ELISA (cELISA), an indirect ELISA (iELISA), and an F-CBA, according to the manufacturers' instructions. Anti-AChR antibody titers were positive in 94/143 (66%) using the cELISA, in 75/143 (52%) using the iELISA and in 61/143 (43%) using the F-CBA (adult and/or fetal). Method agreement, evaluated by concordant pairs and Cohen's kappa, was as follows: cELISA-iELISA: 110/143 (77%), k = 0.53 (95%CI 0.40-0.66); cELISA-F-CBA: 108/143 (76%), k = 0.53 (95%CI 0.41-0.66); iELISA-F-CBA: 121/143 (85%), k = 0.70 (95%CI 0.57-0.80). Our findings show that the cELISA has better analytical performance than the iELISA and F-CBA. However, the iELISA and F-CBA show the highest concordance.
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Affiliation(s)
- Caterina Maria Gambino
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Clinical Laboratory Medicine, University of Palermo, 90127 Palermo, Italy
- Department of Laboratory Medicine, University Hospital "P. Giaccone", 90127 Palermo, Italy
| | - Luisa Agnello
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Clinical Laboratory Medicine, University of Palermo, 90127 Palermo, Italy
| | - Anna Maria Ciaccio
- Department of Health Promotion, Maternal and Infant Care, Internal Medicine and Medical Specialties "G. D'Alessandro", University of Palermo, 90127 Palermo, Italy
| | - Concetta Scazzone
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Clinical Laboratory Medicine, University of Palermo, 90127 Palermo, Italy
| | - Matteo Vidali
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Vincenzo Di Stefano
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Unit of Neurology, University of Palermo, 90127 Palermo, Italy
| | - Salvatore Milano
- Department of Laboratory Medicine, University Hospital "P. Giaccone", 90127 Palermo, Italy
| | - Filippo Brighina
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Unit of Neurology, University of Palermo, 90127 Palermo, Italy
| | - Giuseppina Candore
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Clinical Laboratory Medicine, University of Palermo, 90127 Palermo, Italy
- Department of Laboratory Medicine, University Hospital "P. Giaccone", 90127 Palermo, Italy
| | - Bruna Lo Sasso
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Clinical Laboratory Medicine, University of Palermo, 90127 Palermo, Italy
- Department of Laboratory Medicine, University Hospital "P. Giaccone", 90127 Palermo, Italy
| | - Marcello Ciaccio
- Department of Biomedicine, Neurosciences and Advanced Diagnostics, Institute of Clinical Biochemistry, Clinical Molecular Medicine and Clinical Laboratory Medicine, University of Palermo, 90127 Palermo, Italy
- Department of Laboratory Medicine, University Hospital "P. Giaccone", 90127 Palermo, Italy
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7
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Kwon YN, Woodhall M, Sung JJ, Kim KK, Lim YM, Kim H, Kim JE, Baek SH, Kim BJ, Park JS, Seok HY, Kim DS, Kwon O, Park KH, Sohn E, Bae JS, Yoon BN, Kim NH, Ahn SW, Choi K, Oh J, Park HJ, Shin KJ, Lee S, Park J, Kim SH, Seok JI, Bae DW, An JY, Joo IS, Choi SJ, Nam TS, Kim S, Park KJ, Kwon KH, Waters P, Hong YH. Clinical pitfalls and serological diagnostics of MuSK myasthenia gravis. J Neurol 2023; 270:1478-1486. [PMID: 36396811 PMCID: PMC9971039 DOI: 10.1007/s00415-022-11458-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/22/2022] [Accepted: 10/25/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND We aimed to evaluate the diagnostic accuracy of enzyme-linked immunosorbent assay (ELISA) for anti-muscle specific tyrosine kinase (MuSK) antibody (Ab) in a large cohort of anti-acetylcholine receptor (AChR) Ab-negative generalized myasthenia gravis (MG), and also to investigate clinical contexts for the diagnosis of MuSK MG. METHODS A retrospective study of 160 patients with a clinical suspicion of AChR Ab-negative generalized MG was performed. The serum samples were tested for anti-clustered AChR Ab by cell-based assay (CBA), anti-MuSK Ab by ELISA, CBA and/or radioimmunoprecipitation assay (RIPA). Clinical data were compared between anti-MuSK Ab-positive MG and double seronegative (AChR and MuSK) MG groups. RESULTS After excluding non-MG and clustered AChR Ab-positive patients, we identified 89 patients as a cohort of AChR Ab-negative generalized MG. Anti-MuSK Ab was positive by ELISA in 22 (24.7%) patients. While CBA identified five additional anti-MuSK Ab-positive patients, the results of ELISA were mostly consistent with CBA and RIPA with Cohen's kappa of 0.80 and 0.90, respectively (p < 0.001). The most frequent differential diagnosis was motor neuron disease particularly of bulbar onset which showed remarkably overlapping clinical and electrophysiological features with MuSK MG at presentation. CONCLUSION While confirming the highest sensitivity of CBA for detecting anti-MuSK Ab, our results highlight the clinical pitfalls in making a diagnosis of MuSK MG and may support a diagnostic utility of MuSK-ELISA in clinical practice.
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Affiliation(s)
- Young Nam Kwon
- Department of Neurology, Seoul National University Seoul Metropolitan Government Boramae Medical Center, Seoul, Republic of Korea
- Department of Neurology, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Mark Woodhall
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, Neuroimmunology Group, University of Oxford, John Radcliffe Hospital, Level 5, West Wing, Headley Way, Oxford, OX3 9DU, UK
| | - Jung-Joon Sung
- Department of Neurology, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Neurology, Seoul National University College of Medicine, Neuroscience Research Institute, Seoul National University Medical Research Council, 20 Boramae-Ro 5-Gil, Dongjak-Gu, Seoul, 07061, Republic of Korea
| | - Kwang-Kuk Kim
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Young-Min Lim
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Hyunjin Kim
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Jee-Eun Kim
- Department of Neurology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Seol-Hee Baek
- Department of Neurology, Korea University College of Medicine, Korea University Anam Hospital, Seoul, Republic of Korea
| | - Byung-Jo Kim
- Department of Neurology, Korea University College of Medicine, Korea University Anam Hospital, Seoul, Republic of Korea
| | - Jin-Sung Park
- Department of Neurology, School of Medicine, Kyungpook National University, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea
| | - Hung Youl Seok
- Department of Neurology, Dongsan Hospital, Keimyung University School of Medicine, Daegu, Republic of Korea
| | - Dae-Seong Kim
- Department of Neurology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea
| | - Ohyun Kwon
- Department of Neurology, Uijeongbu Eulji Medical Center, Eulji University School of Medicine, Uijeongbu, Republic of Korea
| | - Kee Hong Park
- Department of Neurology, Seoul Medical Center, Seoul, Republic of Korea
| | - Eunhee Sohn
- Department of Neurology, Chungnam National University College of Medicine, Chungnam National University Hospital, Daejeon, Republic of Korea
| | - Jong Seok Bae
- Department of Neurology, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Republic of Korea
| | - Byung-Nam Yoon
- Department of Neurology, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Republic of Korea
| | - Nam-Hee Kim
- Department of Neurology, Dongguk University Ilsan Hospital, Goyang, Republic of Korea
| | - Suk-Won Ahn
- Department of Neurology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea
| | - Kyomin Choi
- Department of Neurology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Republic of Korea
| | - Jeeyoung Oh
- Department of Neurology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Republic of Korea
| | - Hyung Jun Park
- Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Kyong Jin Shin
- Department of Neurology, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Republic of Korea
| | - Sanggon Lee
- Department of Neurology, Hanyang University College of Medicine, Seoul, Republic of Korea
| | - Jinseok Park
- Department of Neurology, Hanyang University College of Medicine, Seoul, Republic of Korea
| | - Seung Hyun Kim
- Department of Neurology, Hanyang University College of Medicine, Seoul, Republic of Korea
| | - Jung Im Seok
- Department of Neurology, School of Medicine, Catholic University of Daegu, Daegu, Republic of Korea
| | - Dae Woong Bae
- Department of Neurology, College of Medicine, St. Vincent Hospital, The Catholic University of Korea, Suwon, Republic of Korea
| | - Jae Young An
- Department of Neurology, College of Medicine, St. Vincent Hospital, The Catholic University of Korea, Suwon, Republic of Korea
| | - In Soo Joo
- Department of Neurology, Ajou University School of Medicine, Suwon, Republic of Korea
| | - Seok-Jin Choi
- Department of Neurology, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Tai-Seung Nam
- Department of Neurology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Sunyoung Kim
- Department of Neurology, University of Ulsan College of Medicine, Ulsan, Republic of Korea
| | - Ki-Jong Park
- Department of Neurology, College of Medicine, Gyeongsang National University, Gyeonsang Institute of Health Science, Jinju, Republic of Korea
| | - Ki-Han Kwon
- Department of Neurology, Hallym University Dongtan Sacred Heart Hospital, Hallym University College of Medicine, Hwaseong, Republic of Korea
| | - Patrick Waters
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, Neuroimmunology Group, University of Oxford, John Radcliffe Hospital, Level 5, West Wing, Headley Way, Oxford, OX3 9DU, UK.
| | - Yoon-Ho Hong
- Department of Neurology, Seoul National University Seoul Metropolitan Government Boramae Medical Center, Seoul, Republic of Korea.
- Department of Neurology, Seoul National University College of Medicine, Neuroscience Research Institute, Seoul National University Medical Research Council, 20 Boramae-Ro 5-Gil, Dongjak-Gu, Seoul, 07061, Republic of Korea.
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8
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Shao K, Yue YX, Zhao LM, Hao HJ, Ding XJ, Jiang P, Yan CZ, Li HF. Optimization of the cut-offs in acetylcholine receptor antibodies and diagnostic performance in myasthenia gravis patients. Clin Chim Acta 2022; 533:122-130. [PMID: 35750085 DOI: 10.1016/j.cca.2022.06.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 06/13/2022] [Accepted: 06/14/2022] [Indexed: 11/19/2022]
Abstract
OBJECTIVE This study aims to establish an optimization procedure to define the cut-offs of quantitative assays for acetylcholine receptor antibody (AChRAb), evaluate their diagnostic performance in myasthenia gravis (MG), and explore the association with clinical features. METHODS Samples from a representative cohort of 77 MG patients, 80 healthy controls (HC) and 80 other autoimmune diseases (OAD) patients were tested using competitive inhibition ELISA and RIA. Raw values (OD and cpm) and processed values (inhibition rate, binding rate and concentration) were used to define the cut-offs with statistical methods, a rough method, and receiver operating characteristic (ROC) curve. Optimal cut-offs were selected by comparing false positive rates in HC and OAD individuals. The diagnostic performance was evaluated in whole MG cohort and subgroups. Agreement between ELISA and RIA for AChRAb positivity were examined with Kappa test and McNemar test. Clinical association with AChRAb was explored by comparison among subgroups and with Spearman rank correlation. RESULTS The optimal cut-offs for AChRAb positivity were determined as OD≤1.79 for ELISA and cpm≥1234.12 for RIA, which derived from statistical method and performed better than those derived from ROC curves. The sensitivity and specificity were 74.03%, 100% for ELISA, and 74.03%, 99.37% for RIA. There was good agreement between ELISA and RIA for AChRAb positivity in whole cohort and subgroups (weighted к ≥0.71, p<0.01; McNemar test, p>0.05). Levels of AChRAb were different in MG subgroups (p<0.01). Correlation between Quantitative Myasthenia Gravis scores and AChRAb levels was moderate for ELISA and RIA (rs=-0.60 and 0.57, p<0.01). CONCLUSION The raw testing values of ELISA and RIA were found as optimal quantitative measures of AChRAb levels. There are good agreements on diagnostic performance between two assays. Quantitative values are more informative than positivity in association with clinical features.
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Affiliation(s)
- Kai Shao
- Department of Central Laboratory and Mitochondrial Medicine Laboratory, Qilu Hospital (Qingdao), Cheeloo College of Medicine, Shandong University, Qingdao, China.
| | - Yao-Xian Yue
- Department of Neurology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China.
| | - Li-Ming Zhao
- Department of Nuclear Medicine, Linyi People's Hospital, Linyi, China.
| | - Hong-Jun Hao
- Laboratory of Neuroimmunology, Peking University First Hospital, Beijing, China.
| | - Xiao-Jun Ding
- Department of Neurology, Qilu Hospital (Qingdao), Cheeloo College of Medicine, Shandong University, Qingdao, China.
| | - Ping Jiang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.
| | - Chuan-Zhu Yan
- Department of Central Laboratory and Mitochondrial Medicine Laboratory, Qilu Hospital (Qingdao), Cheeloo College of Medicine, Shandong University, Qingdao, China; Department of Neurology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China.
| | - Hai-Feng Li
- Department of Neurology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China; Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.
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Comparative Analysis of BIOCHIP Mosaic-Based Indirect Immunofluorescence with Enzyme-Linked Immunosorbent Assay for Diagnosing Myasthenia Gravis. Diagnostics (Basel) 2021; 11:diagnostics11112098. [PMID: 34829445 PMCID: PMC8619605 DOI: 10.3390/diagnostics11112098] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/04/2021] [Accepted: 11/10/2021] [Indexed: 11/17/2022] Open
Abstract
Background: The detection of anti-acetylcholine receptor (AChR) and anti-muscle-specific tyrosine kinase (MuSK) antibodies is useful in myasthenia gravis (MG) diagnosis and management. BIOCHIP mosaic-based indirect immunofluorescence is a novel analytical method, which employs the simultaneous detection of anti-AChR and anti-MuSK antibodies in a single miniature incubation field. In this study, we compare, for the first time, the BIOCHIP MG mosaic with conventional enzyme-linked immunosorbent assay (ELISA) in the diagnosis of MG. Methods: A total of 71 patients with MG diagnosis were included in the study. Anti-AChR and anti-MuSK antibodies were measured separately by two different ELISA and simultaneously by BIOCHIP. The results were then compared. Results: The overall concordance between ELISA and BIOCHIP for anti-AChR reactivity was 74%. Cohen’s kappa was 0.51 (95% CI 0.32–0.71), which corresponds to 90% of the maximum possible kappa (0.57), given the observed marginal frequencies. The overall concordance for anti-MuSK reactivity was 84%. Cohen’s kappa was 0.11 (95% CI 0.00–0.36), which corresponds to 41% of the maximum possible kappa (0.27). Conclusion: The overall concordance among assays is not optimal.
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Zhao S, Zhang K, Ren K, Lu J, Ma C, Zhao C, Li Z, Guo J. Clinical features, treatment and prognosis of MuSK antibody-associated myasthenia gravis in Northwest China: a single-centre retrospective cohort study. BMC Neurol 2021; 21:428. [PMID: 34732168 PMCID: PMC8567678 DOI: 10.1186/s12883-021-02439-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/14/2021] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND AND PURPOSE To summarize the clinical characteristics of patients with muscle-specific kinase antibody-associated myasthenia gravis (MuSK-MG) and to evaluate the therapeutic responses to different treatment regimes. METHODS Eighteen MuSK-MG patients admitted in our department between October 2017 and September 2020 were included. Clinical parameters were collected and the responses to different immunosuppressive drugs were assessed by MGFA Postintervention Status (MGFA-PIS). Meanwhile, the correlation between QMG scores and MuSK antibody titers were analyzed and MuSK antibody (MuSK-ab) titers were compared before and after therapy based on different immunosuppressive treatment regimes. RESULTS Female predominance (ratio of females to males, 15:3) was evident in the study population, with the average onset age of (40.28 ± 18.57) years and the median disease course of 30.50 months (interquartile range [IQR], 17.50-44.75 months). Ocular manifestation was the most common onset symptom (11/18; 61.11%), and mild symmetrical ptosis was most frequent. Bulbar symptoms had the highest incidence of 88.89% over the entire disease course. Abnormal responses to RNS test were recorded most frequently on the musculus deltoideus (83.33%). All patients were treated with prednisone (Pred) alone or plus azathioprine (AZA), tacrolimus (TAC) or low-dose rituximab (RTX), and 17 (94.44%) of them achieved a favorable outcome defined as minimal manifestation (MM) or better. In general, an obvious positive correlation between QMG score and MuSK-ab titer (r = 0.710, P < 0.001) were found in all patients. A more significant reduction of MuSK-ab titers was observed in patients receiving TAC or RTX plus Pred than those receiving AZA plus Pred. CONCLUSIONS The prominent clinical manifestations of ocular and bulbar muscles involvements, together with abnormal RNS response mostly recorded on the musculus deltoideus and better efficacy associated with TAC or low-dose RTX plus Pred, provide a more exhaustive picture of MuSK-MG, particularly in Northwest China.
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Affiliation(s)
- Sijia Zhao
- Department of Neurology, Tangdu Hospital, Air Force Medical University, Xi'an, 710038, Shaanxi Province, China
| | - Kai Zhang
- Department of Intensive Care Unit, Xi'an No.3 Hospital, Xi'an, 710018, Shaanxi Province, China
| | - Kaixi Ren
- Department of Neurology, Tangdu Hospital, Air Force Medical University, Xi'an, 710038, Shaanxi Province, China
| | - Jiarui Lu
- Department of Neurology, Tangdu Hospital, Air Force Medical University, Xi'an, 710038, Shaanxi Province, China
| | - Chao Ma
- Department of Cardiology, Tangdu Hospital, Air Force Medical University, Xi'an, 710038, Shaanxi Province, China
| | - Cong Zhao
- Department of Neurology, Air Force Medical Center of PLA, Beijing, 100142, China
| | - Zhuyi Li
- Department of Neurology, Tangdu Hospital, Air Force Medical University, Xi'an, 710038, Shaanxi Province, China.
| | - Jun Guo
- Department of Neurology, Tangdu Hospital, Air Force Medical University, Xi'an, 710038, Shaanxi Province, China.
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11
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Li Y, Dong X, Li Z, Peng Y, Jin W, Zhou R, Jiang F, Xu L, Luo Z, Yang H. Characteristics of myasthenia gravis in elderly patients: a retrospective study. Neurol Sci 2021; 43:2775-2783. [PMID: 34677704 DOI: 10.1007/s10072-021-05599-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 09/06/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND The incidence of myasthenia gravis (MG) is increasing, and its characteristics in elderly patients are believed to differ from those in younger patients. However, only a few studies have focused on elderly patients with MG. OBJECTIVE To review the characteristics of MG in elderly patients and evaluate whether older age is an independent factor associated with achieving minimal manifestation status (MMS). METHODS This retrospective cohort study included 367 patients (319 non-elderly and 48 elderly patients) with MG enrolled at Xiangya Hospital from September 1, 2016, to December 31, 2018. We collected demographic data and information regarding comorbidities, antibody status, Myasthenia Gravis Foundation of America classification, affected muscle groups, thymoma, and treatment. MMS was defined as the primary outcome. RESULTS Comorbidities were more common in elderly than in younger patients with MG. Anti-acetylcholine receptor antibody was the dominant subtype, whereas anti-muscle-specific tyrosine kinase antibody was rare and detected only in non-elderly patients. Elderly patients were more likely than younger patients to have generalized MG, but the frequency of thymoma was lower (28.5% vs. 10.4%, p = 0.0078). MMS or better was achieved in 154 (48.3%) and 13 (27.1%) non-elderly and elderly patients, respectively. Older age did not appear to be an independent factor associated with MMS (hazard ratio = 0.625; 95% confidence interval, 0.345-1.131). CONCLUSIONS Older age was not an independent factor for a worse prognosis in patients with MG. The treatment of elderly patients with MG should be individually tailored.
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Affiliation(s)
- Yi Li
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan, 410000, People's Republic of China
| | - Xiaohua Dong
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan, 410000, People's Republic of China
| | - Zhibin Li
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan, 410000, People's Republic of China
| | - Yuyao Peng
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan, 410000, People's Republic of China
| | - Wanlin Jin
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan, 410000, People's Republic of China
| | - Ran Zhou
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan, 410000, People's Republic of China
| | - Fei Jiang
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan, 410000, People's Republic of China
| | - Liqun Xu
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan, 410000, People's Republic of China
| | - Zhaohui Luo
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan, 410000, People's Republic of China
| | - Huan Yang
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan, 410000, People's Republic of China.
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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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13
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Zhou Y, Yan C, Gu X, Zhou L, Lu J, Zhu W, Huan X, Luo S, Zhong H, Lin J, Lu J, Zhao C, Xi J. Short-term effect of low-dose rituximab on myasthenia gravis with muscle-specific tyrosine kinase antibody. Muscle Nerve 2021; 63:824-830. [PMID: 33745138 DOI: 10.1002/mus.27233] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 03/14/2021] [Accepted: 03/16/2021] [Indexed: 12/15/2022]
Abstract
INTRODUCTION/AIMS The study aims to investigate the short-term efficacy of low-dose rituximab and its effect on immunological biomarker levels in myasthenia gravis (MG) patients with antibodies against muscle-specific tyrosine kinase (MuSK-MG). METHODS Twelve MuSK-MG patients were enrolled in this prospective, open-label, self-controlled pilot study. Clinical severity was evaluated at baseline and 6 mo after a single rituximab treatment (600 mg). B lymphocyte subtypes, MuSK antibody titers, together with levels of immunoglobulins, serum B-cell activating factor (BAFF), a proliferation-inducing ligand (APRIL), soluble CD40L, and four exosomal microRNAs were evaluated. A correlation matrix to reveal pairwise relationships among above variables was also generated. RESULTS The single rituximab treatment significantly lowered the clinical severity scores and reduced daily dosage of prednisone (P = .032) at 6 mo. MuSK antibody titers decreased (P = .035) without significant changes in immunoglobulin levels. Serum BAFF level increased (P = .010), which negatively correlated with the percentages of B cells in lymphocytes as well as clinical severity. Additionally, serum exosomal miR-151a-3p showed a reduction of 28.1% (P = .031). DISCUSSION We confirmed the clinical efficacy of low-dose rituximab in MuSK-MG, accompanied by a decrease in MuSK antibody titers and an increase in serum BAFF. Serum BAFF levels negatively correlated with B-cell counts as well as clinical severity.
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Affiliation(s)
- Yufan Zhou
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Chong Yan
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Xinyu Gu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Lei Zhou
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Jun Lu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Wenhua Zhu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Xiao Huan
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Sushan Luo
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Huahua Zhong
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Jie Lin
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Jiahong Lu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Chongbo Zhao
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China.,Department of Neurology, Jing'an District Centre Hospital of Shanghai, Shanghai, China
| | - Jianying Xi
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
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14
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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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15
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Cao M, Koneczny I, Vincent A. Myasthenia Gravis With Antibodies Against Muscle Specific Kinase: An Update on Clinical Features, Pathophysiology and Treatment. Front Mol Neurosci 2020; 13:159. [PMID: 32982689 PMCID: PMC7492727 DOI: 10.3389/fnmol.2020.00159] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 08/03/2020] [Indexed: 12/24/2022] Open
Abstract
Muscle Specific Kinase myasthenia gravis (MuSK-MG) is an autoimmune disease that impairs neuromuscular transmission leading to generalized muscle weakness. Compared to the more common myasthenia gravis with antibodies against the acetylcholine receptor (AChR), MuSK-MG affects mainly the bulbar and respiratory muscles, with more frequent and severe myasthenic crises. Treatments are usually less effective with the need for prolonged, high doses of steroids and other immunosuppressants to control symptoms. Under physiological condition, MuSK regulates a phosphorylation cascade which is fundamental for the development and maintenance of postsynaptic AChR clusters at the neuromuscular junction (NMJ). Agrin, secreted by the motor nerve terminal into the synaptic cleft, binds to low density lipoprotein receptor-related protein 4 (LRP4) which activates MuSK. In MuSK-MG, monovalent MuSK-IgG4 autoantibodies block MuSK-LRP4 interaction preventing MuSK activation and leading to the dispersal of AChR clusters. Lower levels of divalent MuSK IgG1, 2, and 3 antibody subclasses are also present but their contribution to the pathogenesis of the disease remains controversial. This review aims to provide a detailed update on the epidemiological and clinical features of MuSK-MG, focusing on the pathophysiological mechanisms and the latest indications regarding the efficacy and safety of different treatment options.
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Affiliation(s)
- Michelangelo Cao
- Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Inga Koneczny
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
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16
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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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17
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Triplett JD, Hardy TA, Riminton DS, Chu SYK, Reddel SW. Association between musk antibody concentrations and the myasthenia gravis composite score in 3 patients: A marker of relapse? Muscle Nerve 2019; 60:307-311. [PMID: 31177576 DOI: 10.1002/mus.26609] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/05/2019] [Indexed: 11/11/2022]
Abstract
INTRODUCTION Muscle-specific tyrosine kinase (MuSK) autoantibody related myasthenia gravis is characterized by bulbar and respiratory manifestations, a poor response to anticholinergics, and a generally good response to plasma exchange and rituximab. It is not known if MuSK-antibody (Ab) levels could be used to predict the clinical course Methods: Three patients for whom frequent long-term monitoring of MuSK-Ab levels and the Myasthenia Gravis Composite (MGC) scores were performed are described. RESULTS A close relationship existed between the MuSK-Ab concentrations and the MGC score. Furthermore, a rise in Ab concentration preceded a more serious clinical relapse in all patients Conclusions: These findings suggest that MuSK-Ab concentrations may be a useful biomarker for the long-term monitoring of MuSK myasthenia gravis, particularly while in clinical remission. This may allow preemptive escalation of therapy to prevent clinical relapse, and conversely permitting greater weaning of unnecessary immunosuppression. Muscle Nerve, 2019.
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Affiliation(s)
- James D Triplett
- Neuroimmunology Clinic, Department of Neurology, Concord Hospital, NSW, Australia
| | - Todd A Hardy
- Neuroimmunology Clinic, Department of Neurology, Concord Hospital, NSW, Australia
| | | | - Shannon Y K Chu
- Molecular Medicine Laboratory, Department of Pathology, Concord Hospital, NSW, Australia
| | - Stephen W Reddel
- Neuroimmunology Clinic, Department of Neurology, Concord Hospital, NSW, Australia
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18
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Trakas N, Tzartos SJ. Immunostick ELISA for rapid and easy diagnosis of myasthenia gravis. J Immunol Methods 2018; 460:107-112. [DOI: 10.1016/j.jim.2018.06.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 06/14/2018] [Accepted: 06/28/2018] [Indexed: 01/20/2023]
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19
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Clinical and scientific aspects of muscle-specific tyrosine kinase-related myasthenia gravis. Curr Opin Neurol 2014; 27:558-65. [DOI: 10.1097/wco.0000000000000136] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Nakata R, Motomura M, Masuda T, Shiraishi H, Tokuda M, Fukuda T, Ando T, Yoshimura T, Tsujihata M, Kawakami A. Thymus histology and concomitant autoimmune diseases in Japanese patients with muscle-specific receptor tyrosine kinase-antibody-positive myasthenia gravis. Eur J Neurol 2013; 20:1272-6. [PMID: 23679930 DOI: 10.1111/ene.12169] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 03/11/2013] [Indexed: 12/01/2022]
Abstract
BACKGROUND AND PURPOSE The differences in the characteristics of thymus histology, coexisting autoimmune diseases and related autoantibodies between anti-muscle-specific receptor tyrosine kinase (MuSK)-antibody (Ab)-positive myasthenia gravis (MG) patients, and anti-acetylcholine receptor (AChR)-Ab-positive MG patients are not clearly defined. METHODS The types of thymus histology, coexisting autoimmune diseases and associated Abs in 83 MuSK-Ab-positive patients nationwide were investigated and were compared with those in AChR-Ab-positive patients followed at our institute (n = 83). As for the autoantibodies associated with thymoma, titin Abs were measured. RESULTS Thymoma was not present in any of the MuSK-Ab-positive patients but presented in 21 patients (25.3%) amongst the AChR-Ab-positive patients. Titin Abs were absent in MuSK-Ab-positive patients but positive in 25 (30.1%) of the AChR-Ab-positive patients. Concomitant autoimmune diseases were present in eight MuSK-Ab-positive patients (9.6%) amongst whom Hashimoto's thyroiditis and rheumatoid arthritis predominated, whereas 22 AChR-Ab-positive patients (26.5%) had one or more concomitant autoimmune diseases of which Graves' disease predominated. CONCLUSIONS Differences in frequency of thymoma and thymic hyperplasia, coexisting autoimmune diseases and autoantibody positivity between MuSK-Ab-positive and AChR-Ab-positive MG were indicated, suggesting that, in contrast with AChR-Ab-positive MG, thymus does not seem to be involved in the pathogenic mechanisms of MuSK-Ab-positive MG.
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Affiliation(s)
- R Nakata
- Department of Clinical Neuroscience and Neurology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
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Zisimopoulou P, Brenner T, Trakas N, Tzartos SJ. Serological diagnostics in myasthenia gravis based on novel assays and recently identified antigens. Autoimmun Rev 2013; 12:924-30. [PMID: 23537507 DOI: 10.1016/j.autrev.2013.03.002] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2013] [Indexed: 10/27/2022]
Abstract
Myasthenia gravis (MG) is the most common immune-mediated disorder of the neuromuscular junction with a prevalence of 200-300/million population and its study has established paradigms for exploring other antibody-mediated diseases. Most MG patients (~85%) have autoantibodies against the muscle acetylcholine receptor (AChR-MG), whereas about 6% of MG patients have autoantibodies against the muscle specific kinase (MuSK-MG). Until recently no autoantibodies could be detected in the remaining patients (seronegative MG). Probably, the most sensitive assays for the detection of the autoantibodies in MG sera have been the radioimmunoprecipitation assays (RIPA) for both types of MG. However, with recent novel methods, not yet used routinely, it has been shown that the "seronegative" MG group includes patients with low levels of autoantibodies or of low affinity, against the known autoantigens, or even with antibodies to recently identified autoantigens. Since MG is heterogeneous in terms of pathophysiology, depending on the autoantigen targeted and on other factors (e.g. presence of thymoma), the serological tests are crucial in verifying the initial clinical diagnosis, whereas frequent measurement of autoantibody levels is important in monitoring the course of the disease and the efficacy of treatment. In addition, in AChR-MG, autoantibodies against the muscle proteins titin and ryanodin receptor have been identified; these antibodies are useful for the classification of MG, indicating the concomitant presence of thymoma, and as prognostic markers.
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Trakas N, Zisimopoulou P, Tzartos SJ. Development of a highly sensitive diagnostic assay for muscle-specific tyrosine kinase (MuSK) autoantibodies in myasthenia gravis. J Neuroimmunol 2011; 240-241:79-86. [DOI: 10.1016/j.jneuroim.2011.09.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 09/16/2011] [Indexed: 10/16/2022]
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23
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Higuchi O, Hamuro J, Motomura M, Yamanashi Y. Autoantibodies to low-density lipoprotein receptor-related protein 4 in myasthenia gravis. Ann Neurol 2011; 69:418-22. [PMID: 21387385 DOI: 10.1002/ana.22312] [Citation(s) in RCA: 315] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction, where acetylcholine receptor (AChR), muscle-specific kinase (MuSK), and low-density lipoprotein (LDL) receptor-related protein 4 (Lrp4) are essential. About 80% and 0% to 10% of patients with generalized MG have autoantibodies to AChR and MuSK, respectively, but pathogenic factors are elusive in others. Here we show that a proportion of AChR antibody-negative patients have autoantibodies to Lrp4. These antibodies inhibit binding of Lrp4 to its ligand and predominantly belong to the immunoglobulin G1 (IgG1) subclass, a complement activator. These findings together indicate the involvement of Lrp4 antibodies in the pathogenesis of AChR antibody-negative MG.
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Affiliation(s)
- Osamu Higuchi
- Division of Genetics, Department of Cancer Biology, the Institute of Medical Science, the University of Tokyo, Japan
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Alseth EH, Maniaol AH, Elsais A, Nakkestad HL, Tallaksen C, Gilhus NE, Skeie GO. Investigation for RAPSN and DOK-7 mutations in a cohort of seronegative myasthenia gravis patients. Muscle Nerve 2011; 43:574-7. [DOI: 10.1002/mus.21919] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2011] [Indexed: 11/12/2022]
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25
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Pal J, Rozsa C, Komoly S, Illes Z. Clinical and biological heterogeneity of autoimmune myasthenia gravis. J Neuroimmunol 2011; 231:43-54. [DOI: 10.1016/j.jneuroim.2010.10.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Abstract
The diagnostic use of antibodies is dependent on sensitivity and specificity of the methods of antibody detection, which have been developed and improved over the years. Here, we review the different methods for the detection of acetylcholine receptor and muscle-specific kinase antibodies, which are, so far, the only antibodies recognised as pathogenic in myasthenia gravis (MG). Seronegative MG patients will benefit from more sensitive methods of antibody detection. The most recent developments in antibody detection assays, particularly those based on cells expressing target antigens, allow rapid and reliable identification of autoantibodies, improving the diagnosis and treatment of MG patients. The same approaches to antibody detection are now being applied to a wide range of other autoantigens and other autoimmune diseases.
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Affiliation(s)
- M Isabel Leite
- Department of Clinical Neurology, John Radcliffe Hospital, University of Oxford, West Wing OX3 9DS, UK
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27
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Fabien N, Monier JC. [Antireceptor and antichannel autoantibodies]. ACTA ACUST UNITED AC 2006; 54:309-16. [PMID: 16848005 DOI: 10.1016/j.patbio.2005.12.003] [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: 10/24/2022]
Abstract
This review of literature concerns the different autoantibodies directed against membrane receptors and ion channels. The target antigens, the associated pathologies, the pathogenesis and the methods of detection of these autoantibodies will be addressed. Some of these autoantibodies are thought to be closely related to the auto-immune disease whereas for some others their pathogenesis role is still unclear. Overall, the roles of antibodies are different between diseases, but the presence of such autoantibodies support the basis of intervening immunotherapy, antibody titers predicted the activity of the diseases and some of them are very specific and become the useful markers for the diagnosis. Some autoantibodies are detected routinely as the antiacetylcholine receptor, voltage-gated potassium and calcium channels autoantibodies whereas most of them are detected very rarely and only by specialized laboratories. This review will be divided in three parts with the following classification: the first group of autoantibodies directed against membrane receptors included receptors with an enzymatic activity (mostly tyrosine kinase) with one transmembrane domain, receptors associated to G protein with seven transmembrane domains, ion channels and receptors associated to the membrane by the glycosylphosphatidylinositol and the second group of intracellular receptor autoantibodies directed to the estrogens, androgens, lamin and kinesin receptors.
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Affiliation(s)
- N Fabien
- Laboratoire d'immunologie, unité fonctionnelle auto-immunité, bâtiment 1G, centre hospitalier Lyon-Sud, Pierre-Bénite cedex, France.
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28
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Vincent A, Leite MI. Neuromuscular junction autoimmune disease: muscle specific kinase antibodies and treatments for myasthenia gravis. Curr Opin Neurol 2005; 18:519-25. [PMID: 16155434 DOI: 10.1097/01.wco.0000180660.57801.3f] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Some of the 20% of myasthenia gravis patients who do not have antibodies to acetylcholine receptors (AChRs) have antibodies to muscle specific kinase (MuSK), but a full understanding of their frequency, the associated clinical phenotype and the mechanisms of action of the antibodies has not yet been achieved. Moreover, some patients do not respond well to conventional corticosteroid therapy. Here we review recent clinical and experimental studies on MuSK antibody associated myasthenia gravis, and summarize the results of newer treatments for myasthenia gravis. RECENT FINDINGS MuSK antibodies are found in a variable proportion of AChR antibody negative myasthenia gravis patients who are often, but not exclusively, young adult females, with bulbar, neck, or respiratory muscle weakness. The thymus histology is normal or only very mildly abnormal. Surprisingly, limb or intercostal muscle biopsies exhibit no reduction in AChR numbers or complement deposition. However, patients without AChR or MuSK antibodies appear to be similar to those with AChR antibodies and may have low-affinity AChR antibodies. A variety of treatments, often intended to enable corticosteroid doses to be reduced, have been used in all types of myasthenia gravis with some success, but they have not been subjected to randomized clinical trials. SUMMARY MuSK antibodies define a form of myasthenia gravis that can be difficult to diagnose, can be life threatening and may require additional treatments. An improved AChR antibody assay may be helpful in patients without AChR or MuSK antibodies. Clinical trials of drugs in other neuroimmunological diseases may help to guide the treatment of myasthenia gravis.
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Affiliation(s)
- Angela Vincent
- Neurosciences Group, Weatherall Institute of Molecular Medicine and Department of Clinical Neurology, University of Oxford, Oxford, UK.
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