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Koneczny I, Tzartos J, Mané-Damas M, Yilmaz V, Huijbers MG, Lazaridis K, Höftberger R, Tüzün E, Martinez-Martinez P, Tzartos S, Leypoldt F. IgG4 Autoantibodies in Organ-Specific Autoimmunopathies: Reviewing Class Switching, Antibody-Producing Cells, and Specific Immunotherapies. Front Immunol 2022; 13:834342. [PMID: 35401530 PMCID: PMC8986991 DOI: 10.3389/fimmu.2022.834342] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 02/28/2022] [Indexed: 12/24/2022] Open
Abstract
Organ-specific autoimmunity is often characterized by autoantibodies targeting proteins expressed in the affected tissue. A subgroup of autoimmunopathies has recently emerged that is characterized by predominant autoantibodies of the IgG4 subclass (IgG4-autoimmune diseases; IgG4-AID). This group includes pemphigus vulgaris, thrombotic thrombocytopenic purpura, subtypes of autoimmune encephalitis, inflammatory neuropathies, myasthenia gravis and membranous nephropathy. Although the associated autoantibodies target specific antigens in different organs and thus cause diverse syndromes and diseases, they share surprising similarities in genetic predisposition, disease mechanisms, clinical course and response to therapies. IgG4-AID appear to be distinct from another group of rare immune diseases associated with IgG4, which are the IgG4-related diseases (IgG4-RLD), such as IgG4-related which have distinct clinical and serological properties and are not characterized by antigen-specific IgG4. Importantly, IgG4-AID differ significantly from diseases associated with IgG1 autoantibodies targeting the same organ. This may be due to the unique functional characteristics of IgG4 autoantibodies (e.g. anti-inflammatory and functionally monovalent) that affect how the antibodies cause disease, and the differential response to immunotherapies of the IgG4 producing B cells/plasmablasts. These clinical and pathophysiological clues give important insight in the immunopathogenesis of IgG4-AID. Understanding IgG4 immunobiology is a key step towards the development of novel, IgG4 specific treatments. In this review we therefore summarize current knowledge on IgG4 regulation, the relevance of class switching in the context of health and disease, describe the cellular mechanisms involved in IgG4 production and provide an overview of treatment responses in IgG4-AID.
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Affiliation(s)
- Inga Koneczny
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Vienna, Austria
- *Correspondence: Inga Koneczny,
| | - John Tzartos
- Neuroimmunology, Tzartos NeuroDiagnostics, Athens, Greece
- 2nd Department of Neurology, “Attikon” University Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Marina Mané-Damas
- Research Group Neuroinflammation and Autoimmunity, Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Netherlands
| | - Vuslat Yilmaz
- Department of Neuroscience, Aziz Sancar Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Maartje G. Huijbers
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
- Department of Neurology, Leiden University Medical Center, Leiden, Netherlands
| | - Konstantinos Lazaridis
- Department of Immunology, Laboratory of Immunology, Hellenic Pasteur Institute, Athens, Greece
| | - Romana Höftberger
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Erdem Tüzün
- Department of Neuroscience, Aziz Sancar Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Pilar Martinez-Martinez
- Research Group Neuroinflammation and Autoimmunity, Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Netherlands
| | - Socrates Tzartos
- Neuroimmunology, Tzartos NeuroDiagnostics, Athens, Greece
- Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
| | - Frank Leypoldt
- Neuroimmunology, Institute of Clinical Chemistry and Department of Neurology, UKSH Kiel/Lübeck, Kiel University, Kiel, Germany
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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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Cai GM, Gao Z, Yue YX, Xie YC, Gao X, Hao HJ, Zhang XJ, Wang Q, Liang B, Li HF. Association between CTLA-4 gene polymorphism and myasthenia gravis in a Chinese cohort. J Clin Neurosci 2019; 69:31-37. [PMID: 31473094 DOI: 10.1016/j.jocn.2019.08.079] [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] [Received: 01/14/2019] [Revised: 04/13/2019] [Accepted: 08/10/2019] [Indexed: 01/13/2023]
Abstract
Abnormal CTLA-4 expression is involved in the development of myasthenia gravis (MG), and serum CTLA-4 levels are positively correlated with serum anti-AChR antibody concentration, which might be related with the severity of MG. Polymorphism in CTLA-4 gene is associated with various autoimmune disorders. We investigated the association of polymorphism in CTLA-4 gene with the clinical variables and severity of MG. The frequencies of alleles and genotypes were compared between 480 MG patients and 487 healthy controls, as well as among subgroups of MG patients. The frequency of rs733618*C allele is significantly higher in MG group and several subgroups than in control group. Genotype is not found as independent factor for essential clinical variables of MG. The frequency of rs231775*A allele is significantly lower in ocular onset subgroup than in control group, and the frequencies of rs231775*A allele and rs3087243*A allele are significantly lower in ocular onset subgroup than in generalized onset subgroup. Genotypes of the two SNPs are found as independent factors for ocular onset. The frequency of rs231775*A allele is significantly lower in mild subgroup than that in control group. Genotype is not found as independent factor for mild severity. A haplotype containing rs733618*C, rs231775*G and rs3087243*G is identified to increase the general risk of MG by 1.278-fold and ocular onset MG subgroup by 1.362-fold. There is association of rs733618 with the general susceptibility of MG, and association of rs231775 and rs3087243 with the susceptibility of ocular onset MG, but no association with the severity of MG.
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Affiliation(s)
- Gao-Mei Cai
- Department of Neurology, Affiliated Hospital of Jining Medical College, No. 89 Guhuai Road, Jining 272000, China
| | - Zhe Gao
- Department of Respiratory and Critical Care Medicine, Affiliated Hospital of Qingdao University, No. 16 Jiangsu Road, Qingdao 266003, China
| | - Yao-Xian Yue
- Department of Neurology, Qilu Hospital of Shandong University, No. 107 Wenhua West Road, Jinan 250012, China
| | - Yan-Chen Xie
- Department of Neurology, Beijing Friendship Hospital, Capital Medical University, No. 95 Yongan Road, Beijing 100050, China
| | - Xiang Gao
- Department of Neurology, Affiliated Hospital of Qingdao University, No. 16 Jiangsu Road, Qingdao 266003, China
| | - Hong-Jun Hao
- Department of Neurology, Peking University First Hospital, No. 8 Xishiku Street, Beijing 100034, China
| | - Xian-Jun Zhang
- Department of Neurology, Affiliated Hospital of Qingdao University, No. 16 Jiangsu Road, Qingdao 266003, China
| | - Qi Wang
- Department of Neurology, Affiliated Hospital of Qingdao University, No. 16 Jiangsu Road, Qingdao 266003, China
| | - Bing Liang
- Department of Neurology, Qilu Hospital of Shandong University, No. 107 Wenhua West Road, Jinan 250012, China
| | - Hai-Feng Li
- Department of Neurology, Xuanwu Hospital, Capital Medical University, No. 45, Changchun Street, Beijing 100053, China.
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Luo J, Lindstrom J. Acetylcholine receptor-specific immunosuppressive therapy of experimental autoimmune myasthenia gravis and myasthenia gravis. Ann N Y Acad Sci 2018; 1413:76-81. [PMID: 29377167 DOI: 10.1111/nyas.13550] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/13/2017] [Accepted: 10/18/2017] [Indexed: 12/14/2022]
Abstract
Experimental autoimmune myasthenia gravis (EAMG) and myasthenia gravis (MG) are caused by autoantibodies to the extracellular domain of muscle nicotinic acetylcholine receptors (AChRs). Autoantibodies to the cytoplasmic domain of AChRs do not cause EAMG because they cannot bind AChRs in vivo. The ideal MG therapy would quickly and permanently suppress only the pathological autoimmune response to AChRs. We have developed a specific immunosuppressive therapy for EAMG that involves immunizing rats with bacterially expressed cytoplasmic domains of human muscle AChRs. Therapy prevents onset of chronic EAMG, rapidly suppresses ongoing EAMG, and is potent, robust, long lasting, and safe, because the therapeutic antigen cannot induce EAMG. The therapy was developed using incomplete Freund's adjuvant, but is likely to work equally well with alum adjuvants routinely used for human immunizations. Therapeutic mechanisms may involve a combination of antibody-mediated feedback suppression and regulatory T and/or B lymphocytes.
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Affiliation(s)
- Jie Luo
- Department of Clinical Sciences and Advanced Medicine, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania
| | - Jon Lindstrom
- Department of Neuroscience, Medical School of the University of Pennsylvania, Philadelphia, Pennsylvania
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Lazaridis K, Baltatzidi V, Trakas N, Koutroumpi E, Karandreas N, Tzartos SJ. Characterization of a reproducible rat EAMG model induced with various human acetylcholine receptor domains. J Neuroimmunol 2017; 303:13-21. [DOI: 10.1016/j.jneuroim.2016.12.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 12/04/2016] [Accepted: 12/05/2016] [Indexed: 01/08/2023]
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Mantegazza R, Cordiglieri C, Consonni A, Baggi F. Animal models of myasthenia gravis: utility and limitations. Int J Gen Med 2016; 9:53-64. [PMID: 27019601 PMCID: PMC4786081 DOI: 10.2147/ijgm.s88552] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Myasthenia gravis (MG) is a chronic autoimmune disease caused by the immune attack of the neuromuscular junction. Antibodies directed against the acetylcholine receptor (AChR) induce receptor degradation, complement cascade activation, and postsynaptic membrane destruction, resulting in functional reduction in AChR availability. Besides anti-AChR antibodies, other autoantibodies are known to play pathogenic roles in MG. The experimental autoimmune MG (EAMG) models have been of great help over the years in understanding the pathophysiological role of specific autoantibodies and T helper lymphocytes and in suggesting new therapies for prevention and modulation of the ongoing disease. EAMG can be induced in mice and rats of susceptible strains that show clinical symptoms mimicking the human disease. EAMG models are helpful for studying both the muscle and the immune compartments to evaluate new treatment perspectives. In this review, we concentrate on recent findings on EAMG models, focusing on their utility and limitations.
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Affiliation(s)
- Renato Mantegazza
- Neurology IV Unit, Neuroimmunology and Neuromuscular Disorders, Foundation IRCCS Neurological Institute "Carlo Besta", Milan, Italy
| | - Chiara Cordiglieri
- Neurology IV Unit, Neuroimmunology and Neuromuscular Disorders, Foundation IRCCS Neurological Institute "Carlo Besta", Milan, Italy
| | - Alessandra Consonni
- Neurology IV Unit, Neuroimmunology and Neuromuscular Disorders, Foundation IRCCS Neurological Institute "Carlo Besta", Milan, Italy
| | - Fulvio Baggi
- Neurology IV Unit, Neuroimmunology and Neuromuscular Disorders, Foundation IRCCS Neurological Institute "Carlo Besta", Milan, Italy
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Aricha R, Reuveni D, Fuchs S, Souroujon MC. Suppression of experimental autoimmune myasthenia gravis by autologous T regulatory cells. J Autoimmun 2015; 67:57-64. [PMID: 26489998 DOI: 10.1016/j.jaut.2015.09.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 09/24/2015] [Accepted: 09/29/2015] [Indexed: 01/12/2023]
Abstract
Adoptive transfer of regulatory T (Treg) cells have been employed effectively for suppression of several animal models for autoimmune diseases. In order to employ Treg cell therapy in patients, it is necessary to generate Treg cells from the patient's own cells (autologous) that would be able to suppress effectively the disease in vivo, upon their reintroduction to the patient. Towards this objective, we report in the present study on a protocol for a successful immune-regulation of experimental autoimmune myasthenia gravis (EAMG) by ex vivo--generated autologous Treg cells. For this protocol bone marrow (BM) cells, are first cultured in the presence of GM-CSF, giving rise to a population of CD11c(+)MHCII(+)CD45RA(+)CD8(-) DCs (BMDCs). Splenic CD4(+) T cells are then co-cultured with the differentiated BM cells and expand to 90% of Foxp3(+) Treg cells. In vitro assay exhibits a similar dose dependent manner in the suppression of T effector cells proliferation between Treg cells obtained from either healthy or sick donors. In addition, both Treg cells inhibit similarly the secretion of IFN-γ from activated splenocytes. Administration of 1 × 10(6) ex-vivo generated Treg cells, I.V, to EAMG rats, modulates the disease following a single treatment, given 3 days or 3 weeks after disease induction. Similar disease inhibition was achieved when CD4 cells were taken from either healthy or sick donors. The disease suppression was accompanied by reduced levels of total AChR specific antibodies in the serum. Moreover, due to the polyclonality of the described Treg cell, we have examined whether this treatment approach could be also employed for the treatment of other autoimmune diseases involving Treg cells. Indeed, we demonstrated that the ex-vivo generated autologous Treg cells suppress Adjuvant Arthritis (AA) in rats. This study opens the way for the application of induced autologous Treg cell therapy for myasthenia gravis, as well as for other human autoimmune diseases involving Treg cells.
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Affiliation(s)
- Revital Aricha
- Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Debby Reuveni
- Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sara Fuchs
- Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel.
| | - Miriam C Souroujon
- Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel; Department of Natural Sciences, The Open University of Israel, Raanana 43107, Israel
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9
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Bu N, Wu HQ, Zhang GL, Zhan SQ, Zhang R, Fan QY, Li YL, Zhai YF, Ren HW. Immature dendritic cell exosomes suppress experimental autoimmune myasthenia gravis. J Neuroimmunol 2015. [DOI: 10.1016/j.jneuroim.2015.04.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Losen M, Martinez-Martinez P, Molenaar PC, Lazaridis K, Tzartos S, Brenner T, Duan RS, Luo J, Lindstrom J, Kusner L. Standardization of the experimental autoimmune myasthenia gravis (EAMG) model by immunization of rats with Torpedo californica acetylcholine receptors--Recommendations for methods and experimental designs. Exp Neurol 2015; 270:18-28. [PMID: 25796590 PMCID: PMC4466156 DOI: 10.1016/j.expneurol.2015.03.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 03/06/2015] [Accepted: 03/10/2015] [Indexed: 12/21/2022]
Abstract
Myasthenia gravis (MG) with antibodies against the acetylcholine receptor (AChR) is characterized by a chronic, fatigable weakness of voluntary muscles. The production of autoantibodies involves the dysregulation of T cells which provide the environment for the development of autoreactive B cells. The symptoms are caused by destruction of the postsynaptic membrane and degradation of the AChR by IgG autoantibodies, predominantly of the G1 and G3 subclasses. Active immunization of animals with AChR from mammalian muscles, AChR from Torpedo or Electrophorus electric organs, and recombinant or synthetic AChR fragments generates a chronic model of MG, termed experimental autoimmune myasthenia gravis (EAMG). This model covers cellular mechanisms involved in the immune response against the AChR, e.g. antigen presentation, T cell-help and regulation, B cell selection and differentiation into plasma cells. Our aim is to define standard operation procedures and recommendations for the rat EAMG model using purified AChR from the Torpedo californica electric organ, in order to facilitate more rapid translation of preclinical proof of concept or efficacy studies into clinical trials and, ultimately, clinical practice.
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Affiliation(s)
- Mario Losen
- Division Neuroscience, Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.
| | - Pilar Martinez-Martinez
- Division Neuroscience, Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Peter C Molenaar
- Division Neuroscience, Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | | | - Socrates Tzartos
- Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
| | - Talma Brenner
- Laboratory of Neuroimmunology, Department of Neurology, The Agnes Ginges Center for Human Neurogenetics, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Rui-Sheng Duan
- Department of Neurology, Shandong Provincial Qianfoshan Hospital, Shandong University, PR China
| | - Jie Luo
- Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, PA, USA
| | - Jon Lindstrom
- Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, PA, USA
| | - Linda Kusner
- Department of Pharmacology & Physiology, The George Washington University, Washington, DC, USA
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Luo J, Lindstrom J. Antigen-specific immunotherapeutic vaccine for experimental autoimmune myasthenia gravis. THE JOURNAL OF IMMUNOLOGY 2014; 193:5044-55. [PMID: 25288571 DOI: 10.4049/jimmunol.1401392] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Myasthenia gravis (MG) and experimental autoimmune myasthenia gravis (EAMG) are caused by Ab-mediated autoimmune responses to muscle nicotinic acetylcholine receptors (AChRs) that impair neuromuscular transmission, thereby causing muscle weakness. Previously, we discovered that i.p. injection of a therapeutic vaccine consisting of bacterially expressed cytoplasmic domains of human AChR subunits reduced the development of chronic EAMG in rats. In this article, we show that immunization with the therapeutic vaccine in adjuvants does not induce EAMG and, thus, is safe. The potency and efficacy of the therapeutic vaccine were greatly increased by s.c. administration of repeated low doses in IFA. Onset of chronic EAMG could be prevented. Established chronic EAMG could be rapidly reversed, modeling therapy of chronic MG. Therapy reduced pathological Abs assayed by immune precipitation of a main immunogenic region chimera. Successfully treated rats exhibited long-term resistance to reinduction of EAMG, suggesting a lasting cure of MG. A long-term effect of therapy was to change the isotype of the pathogenic Ab response from IgG2b, which fixes complement, to IgG1, which does not. Prevention and reversal of chronic EAMG was not caused by the isotype switch, but the isotype switch may contribute to resistance to reinduction of EAMG. Immunization with AChR cytoplasmic domains in adjuvant is promising as a safe, Ag-specific, potent, effective, rapidly acting, and long-lasting therapeutic approach to MG.
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Affiliation(s)
- Jie Luo
- Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, PA 19104
| | - Jon Lindstrom
- Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, PA 19104
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Fuchs S, Aricha R, Reuveni D, Souroujon MC. Experimental Autoimmune Myasthenia Gravis (EAMG): from immunochemical characterization to therapeutic approaches. J Autoimmun 2014; 54:51-9. [PMID: 24970384 DOI: 10.1016/j.jaut.2014.06.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 06/04/2014] [Indexed: 12/22/2022]
Abstract
Myasthenia Gravis (MG) is an organ-specific autoimmune disease. In high percentage of patients there are autoantibodies to the nicotinic acetylcholine receptor (AChR) that attack AChR on muscle cells at the neuromuscular junction, resulting in muscle weakness. Experimental Autoimmune Myasthenia Gravis (EAMG) is an experimental model disease for MG. EAMG is induced in several animal species by immunization with acetylcholine receptor (AChR), usually isolated from the electric organ of electric fish, which is a rich source for this antigen. Our lab has been involved for several decades in research of AChR and of EAMG. The availability of an experimental autoimmune disease that mimics in many aspects the human disease, provides an excellent model system for elucidating the immunological nature and origin of MG, for studying various existing treatment modalities and for attempting the development of novel treatment approaches. In this review in honor of Michael Sela and Ruth Arnon, we report first on our early pioneering contributions to research on EAMG. These include the induction of EAMG in several animal species, early attempts for antigen-specific treatment for EAMG, elicitation and characterization of monoclonal antibodies and anti-idiotypic antibodies, measuring humoral and cellular AChR-specific immune responses in MG patient and more. In the second part of the review we discuss more recent studies from our lab towards developing and testing novel treatment approaches for myasthenia. These include antigen-dependent treatments aimed at specifically abrogating the humoral and cellular anti-AChR responses, as well as immunomodulatory approaches that could be used either alone, or in conjunction with antigen-specific treatments, or alternatively, serve as steroid-sparing agents.
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Affiliation(s)
- Sara Fuchs
- Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel.
| | - Revital Aricha
- Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Debby Reuveni
- Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel; Department of Natural Sciences, The Open University of Israel, Raanana, Israel
| | - Miriam C Souroujon
- Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel; Department of Natural Sciences, The Open University of Israel, Raanana, Israel
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Cohen-Kaminsky S, Jambou F. Prospects for a T-cell receptor vaccination against myasthenia gravis. Expert Rev Vaccines 2014; 4:473-92. [PMID: 16117705 DOI: 10.1586/14760584.4.4.473] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
T-cell receptor (TCR) vaccination has been proposed as a specific therapy against autoimmune diseases. It is already used in clinical trials, which are supported by pharmaceutical companies for the treatment of multiple sclerosis, rheumatoid arthritis and psoriasis. Current vaccine developments are focusing on enhancement of immunogenicity as well as selecting the best route of immunization and adjuvant to favor the therapeutic effect. In the meantime, academic laboratories are tackling the regulatory mechanisms involved in the beneficial effect of the vaccines to further understand how to control the therapeutic tool. Indeed, several examples in experimental models of autoimmune diseases indicate that any specific therapy may rely on a delicate balance between the pathogenic and regulatory mechanisms. This review presents a critical analysis of the potential of such therapy in myasthenia gravis, a prototype antibody-mediated disease. Indeed, a specific pathogenic T-cell target population and a TCR-specific regulatory mechanism mediated by anti-TCR antibodies and involved in protection from the disease have recently been identified in a patient subgroup. The presence of spontaneous anti-TCR antibodies directed against the pathogenic T-cells that may be boosted by a TCR vaccine provides a rationale for such therapy in myasthenia gravis. The development of this vaccine may well benefit from experience gained in the other autoimmune diseases in which clinical trials are ongoing.
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Affiliation(s)
- Sylvia Cohen-Kaminsky
- UMR 8078 Remodelage Tissulaire et Fonctionnel: Signalisation et Physiopathologie, Institut Paris Sud Cytokines, Université Paris-Sud, Hôpital Marie Lannelongue, 92350 Le Plessis-Robinson, France.
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Huijbers MG, Lipka AF, Plomp JJ, Niks EH, van der Maarel SM, Verschuuren JJ. Pathogenic immune mechanisms at the neuromuscular synapse: the role of specific antibody-binding epitopes in myasthenia gravis. J Intern Med 2014; 275:12-26. [PMID: 24215230 DOI: 10.1111/joim.12163] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Autoantibodies against three different postsynaptic antigens and one presynaptic antigen at the neuromuscular junction are known to cause myasthenic syndromes. The mechanisms by which these antibodies cause muscle weakness vary from antigenic modulation and complement-mediated membrane damage to inhibition of endogenous ligand binding and blocking of essential protein-protein interactions. These mechanisms are related to the autoantibody titre, specific epitopes on the target proteins and IgG autoantibody subclass. We here review the role of specific autoantibody-binding epitopes in myasthenia gravis, their possible relevance to the pathophysiology of the disease and potential implications of epitope mapping knowledge for new therapeutic strategies.
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Affiliation(s)
- M G Huijbers
- Department of Neurology, Leiden University Medical Center, Leiden, the Netherlands; Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
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Chae CS, Kwon HK, Hwang JS, Kim JE, Im SH. Prophylactic effect of probiotics on the development of experimental autoimmune myasthenia gravis. PLoS One 2012; 7:e52119. [PMID: 23284891 PMCID: PMC3527378 DOI: 10.1371/journal.pone.0052119] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 11/12/2012] [Indexed: 12/03/2022] Open
Abstract
Probiotics are live bacteria that confer health benefits to the host physiology. Although protective role of probiotics have been reported in diverse diseases, no information is available whether probiotics can modulate neuromuscular immune disorders. We have recently demonstrated that IRT5 probiotics, a mixture of 5 probiotics, could suppress diverse experimental disorders in mice model. In this study we further investigated whether IRT5 probiotics could modulate the progression of experimental autoimmune myasthenia gravis (EAMG). Myasthenia gravis (MG) is a T cell dependent antibody mediated autoimmune disorder in which acetylcholine receptor (AChR) at the neuromuscular junction is the major auto-antigen. Oral administration of IRT5 probiotics significantly reduced clinical symptoms of EAMG such as weight loss, body trembling and grip strength. Prophylactic effect of IRT5 probiotics on EMAG is mediated by down-regulation of effector function of AChR-reactive T cells and B cells. Administration of IRT5 probiotics decreased AChR-reactive lymphocyte proliferation, anti-AChR reactive IgG levels and inflammatory cytokine levels such as IFN-γ, TNF-α, IL-6 and IL-17. Down-regulation of inflammatory mediators in AChR-reactive lymphocytes by IRT5 probiotics is mediated by the generation of regulatory dendritic cells (rDCs) that express increased levels of IL-10, TGF-β, arginase 1 and aldh1a2. Furthermore, DCs isolated from IRT5 probiotics-fed group effectively converted CD4+ T cells into CD4+Foxp3+ regulatory T cells compared with control DCs. Our data suggest that IRT5 probiotics could be applicable to modulate antibody mediated autoimmune diseases including myasthenia gravis.
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Affiliation(s)
- Chang-Suk Chae
- School of Life Sciences and Immune Synapse Research Center, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju, Korea
| | - Ho-Keun Kwon
- School of Life Sciences and Immune Synapse Research Center, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju, Korea
| | - Ji-Sun Hwang
- School of Life Sciences and Immune Synapse Research Center, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju, Korea
| | - Jung-Eun Kim
- School of Life Sciences and Immune Synapse Research Center, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju, Korea
| | - Sin-Hyeog Im
- School of Life Sciences and Immune Synapse Research Center, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju, Korea
- * E-mail:
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Goldmann K, Hoffmann J, Eckl S, Spriewald BM, Ensminger SM. Attenuation of transplant arteriosclerosis by oral feeding of major histocompatibility complex encoding chitosan-DNA nanoparticles. Transpl Immunol 2012; 28:9-13. [PMID: 23220147 DOI: 10.1016/j.trim.2012.11.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 11/23/2012] [Accepted: 11/26/2012] [Indexed: 01/01/2023]
Abstract
One promising approach for the induction of transplant tolerance is the pre-treatment of transplant recipients with donor MHC-alloantigen. Our study focuses on the oral delivery of MHC-antigen encoding genes via chitosan-DNA nanoparticles to modulate the alloimmune response in order to reduce the development of transplant arteriosclerosis, the hallmark feature of chronic rejection after heart transplantation. Therefore, we performed fully allogeneic mouse abdominal aortic transplants using C57BL/6 (H2(b)) mice as donors and CBA.J (H2(k)) mice as recipients. Aortic grafts were analyzed by histology and morphometry on day 30 after transplantation, levels of circulating alloantibodies were detected by FACS analysis. Pre-treatment of recipient mice with chitosan-DNA nanoparticles encoding for K(b), one of the MHC-I molecules of the donor, resulted in a significant reduction of intimal proliferation compared to untreated controls. When Ovalbumin was fed instead of K(b) encoding nanoparticles (K(b)-NP) or Balb/c (H2(d)) grafts were used instead of C57BL/6 (H2(b)) grafts as antigen controls, both groups showed no reduction of intimal thickness indicating an antigen-specific mechanism. In addition, analysis of peripheral blood of the transplanted mice showed significant suppression of alloantibody formation in the K(b)-NP fed group compared to all other allogeneic transplanted groups suggesting modulation of the humoral immune response. These results demonstrate the potential of chitosan-DNA nanoparticles to induce K(b)-specific tolerance and to reduce the development of transplant arteriosclerosis.
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Affiliation(s)
- Katja Goldmann
- Department of Internal Medicine 5, Hematology/Oncology and Institute for Clinical Immunology, Friedrich-Alexander University Erlangen-Nürnberg, Glückstrasse 4A, 91054 Erlangen, Germany.
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18
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Oral gene application using chitosan-DNA nanoparticles induces transferable tolerance. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2012; 19:1758-64. [PMID: 22933401 DOI: 10.1128/cvi.00186-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Oral tolerance is a promising approach to induce unresponsiveness to various antigens. The development of tolerogenic vaccines could be exploited in modulating the immune response in autoimmune disease and allograft rejection. In this study, we investigated a nonviral gene transfer strategy for inducing oral tolerance via antigen-encoding chitosan-DNA nanoparticles (NP). Oral application of ovalbumin (OVA)-encoding chitosan-DNA NP (OVA-NP) suppressed the OVA-specific delayed-type hypersensitivity (DTH) response and anti-OVA antibody formation, as well as spleen cell proliferation following OVA stimulation. Cytokine expression patterns following OVA stimulation in vitro showed a shift from a Th1 toward a Th2/Th3 response. The OVA-NP-induced tolerance was transferable from donor to naïve recipient mice via adoptive spleen cell transfer and was mediated by CD4(+)CD25(+) T cells. These findings indicate that nonviral oral gene transfer can induce regulatory T cells for antigen-specific immune modulation.
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Abstract
Myasthenia gravis is an autoimmune neuromuscular disorder. There are several treatment options, including symptomatic treatment (acetylcholinesterase inhibitors), short-term immunosuppression (corticosteroids), long-term immunosuppression (azathioprine, cyclosporine, cyclophosphamide, methotrexate, mycophenolate mofetil, rituximab, tacrolimus), rapid acting short-term immunomodulation (intravenous immunoglobulin, plasma exchange), and long-term immunomodulation (thymectomy). This review explores in detail these different treatment options. Potential future treatments are also discussed.
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Aricha R, Mizrachi K, Fuchs S, Souroujon MC. Blocking of IL-6 suppresses experimental autoimmune myasthenia gravis. J Autoimmun 2011; 36:135-41. [DOI: 10.1016/j.jaut.2010.12.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2010] [Revised: 11/23/2010] [Accepted: 12/06/2010] [Indexed: 12/17/2022]
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Abstract
Immunosuppression is the mainstay of treatment for myasthenia gravis (MG). In this paper, we review the mechanisms of action and clinical application of corticosteroids and different classes of immunosuppressive drugs that are currently used in MG patients, and present the results of their use in more than 1000 patients with MG seen at our two centers. Immunosuppressive treatment was considered along with, or as an alternative to thymectomy in MG patients with disabling weakness, not adequately controlled with anticholinesterase drugs. Overall, 82% of our patients received immunosuppressants for at least 1 year, with frequencies varying according to disease severity, from 93-95% of those with thymoma or MuSK antibodies to 72% in ocular myasthenia. Prednisone was used in the great majority of patients, azathioprine was the first-choice immunosuppressant; mycophenolate mofetil and cyclosporine were used as second-choice agents. All clinical forms of MG benefited from immunosuppression: the rate of remission or minimal manifestations ranged from 85% in ocular myasthenia to 47% in thymoma-associated disease. Treatment was ultimately withdrawn in nearly 20% of anti-AChR positive early-onset patients, but in only 7% of thymoma cases. The risk of complications appears to depend on drug dosage, treatment duration, and patient characteristics, the highest rate of serious side effects (20%) having been found in late-onset MG and the lowest (4%) in early-onset disease. Although nonspecific, current immunosuppressive treatment is highly effective in most MG patients. Lack of randomized evidence, the need for prolonged administration, and unwanted effects are still relevant limitations to its use.
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22
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Wekerle H, Hohlfeld R. Zero tolerance (to acetylcholine receptor) and ways to overcome it. Ann Neurol 2010; 67:422-4. [PMID: 20437576 DOI: 10.1002/ana.22025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Luo J, Kuryatov A, Lindstrom JM. Specific immunotherapy of experimental myasthenia gravis by a novel mechanism. Ann Neurol 2010; 67:441-51. [PMID: 20437579 DOI: 10.1002/ana.21901] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Myasthenia gravis (MG) and its animal model, experimental autoimmune myasthenia gravis (EAMG), are antibody (Ab)-mediated autoimmune diseases, in which autoantibodies bind to and cause loss of muscle nicotinic acetylcholine receptors (AChRs) at the neuromuscular junction. To develop a specific immunotherapy of MG, we treated rats with ongoing EAMG by intraperitoneal injection of bacterially-expressed human muscle AChR constructs. METHODS Rats with ongoing EAMG received intraperitoneal treatment with the constructs weekly for 5 weeks beginning after the acute phase. Autoantibody concentration, subclassification, and specificity were analyzed to address the underlying therapeutic mechanism. RESULTS EAMG was specifically suppressed by diverting autoantibody production away from pathologically relevant specificities directed at epitopes on the extracellular surface of muscle AChRs toward pathologically irrelevant epitopes on the cytoplasmic domain. A mixture of subunit cytoplasmic domains was more effective than a mixture containing both extracellular and cytoplasmic domains or than only the extracellular domain of alpha1 subunits. INTERPRETATION Therapy using only cytoplasmic domains, which lack pathologically relevant epitopes, avoids the potential liability of boosting the pathological response. Use of a mixture of bacterially-expressed human muscle AChR cytoplasmic domains for antigen-specific immunosuppression of myasthenia gravis has the potential to be specific, robust, and safe.
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Affiliation(s)
- Jie Luo
- Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, PA 19104-6074, USA
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Souroujon MC, Brenner T, Fuchs S. Development of novel therapies for MG: Studies in animal models. Autoimmunity 2010; 43:446-60. [DOI: 10.3109/08916930903518081] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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25
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Yi HJ, Chae CS, So JS, Tzartos SJ, Souroujon MC, Fuchs S, Im SH. Suppression of experimental myasthenia gravis by a B-cell epitope-free recombinant acetylcholine receptor. Mol Immunol 2008; 46:192-201. [DOI: 10.1016/j.molimm.2008.08.264] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 07/31/2008] [Accepted: 08/05/2008] [Indexed: 11/16/2022]
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26
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Lindstrom J, Luo J, Kuryatov A. Myasthenia gravis and the tops and bottoms of AChRs: antigenic structure of the MIR and specific immunosuppression of EAMG using AChR cytoplasmic domains. Ann N Y Acad Sci 2008; 1132:29-41. [PMID: 18567851 DOI: 10.1196/annals.1405.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The main immunogenic region (MIR), against which half or more of the autoantibodies to acetylcholine receptors (AChRs) in myasthenia gravis (MG) or experimental autoimmune MG (EAMG) are directed, is located at the extracellular end of alpha1 subunits. Rat monoclonal antibodies (mAbs) to the MIR efficiently compete with MG patient autoantibodies for binding to human muscle AChRs. Antibodies bound to the MIR do not interfere with cholinergic ligand binding or AChR function, but target complement and trigger antigenic modulation. Rat mAbs to the MIR also bind to human ganglionic AChR alpha3 subunits, but MG patient antibodies do not. By making chimeras of alpha1 subunits with alpha7 subunits or ACh binding protein, the structure of the MIR and its functional effects are being investigated. Many mAbs to the MIR bind only to the native conformation of alpha1 subunits because they bind to sequences that are adjacent only in the native structure. The MIR epitopes recognized by these mAbs are not recognized by most patient antibodies whose epitopes must be nearby. The presence of the MIR epitopes in alpha1/alpha7 chimeras greatly promotes AChR expression and sensitivity to activation. EAMG can be suppressed by treatment with denatured, bacterially expressed mixtures of extracellular and cytoplasmic domains of human alpha1, beta1, gamma, delta, and epsilon subunits. A mixture of only the cytoplasmic domains not only avoids the potential liability of provoking formation antibodies to pathologically significant epitopes on the extracellular surface, but also potently suppresses the development of EAMG.
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Affiliation(s)
- Jon Lindstrom
- Department of Neuroscience, Medical School of the University of Pennsylvania, 217 Stemmler Hall, Philadelphia, PA 19104, USA.
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Menon RT, Feferman T, Aricha R, Souroujon MC, Fuchs S. Suppression of experimental autoimmune myasthenia gravis by combination therapy: Pentoxifylline as a steroid-sparing agent. J Neuroimmunol 2008; 201-202:128-35. [DOI: 10.1016/j.jneuroim.2008.05.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 05/20/2008] [Accepted: 05/21/2008] [Indexed: 01/29/2023]
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Aricha R, Feferman T, Fuchs S, Souroujon MC. Ex vivo generated regulatory T cells modulate experimental autoimmune myasthenia gravis. THE JOURNAL OF IMMUNOLOGY 2008; 180:2132-9. [PMID: 18250419 DOI: 10.4049/jimmunol.180.4.2132] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Naturally occurring CD4(+)CD25(+) regulatory T (Treg) cells are key players in immune tolerance and have therefore been suggested as potential therapeutic tools for autoimmune diseases. In myasthenia gravis (MG), reduced numbers or functionally impaired Treg cells have been reported. We have observed that PBL from myasthenic rats contain decreased numbers of CD4(+)CD25(high)Foxp3(+) cells as compared with PBL from healthy controls, and we have tested whether Treg cells from healthy donors can suppress experimental autoimmune MG in rats. Because the number of naturally occurring Treg cells is low, we used an approach for a large-scale ex vivo generation of functional Treg cells from CD4(+) splenocytes of healthy donor rats. Treg cells were generated ex vivo from CD4(+) cells by stimulation with anti-CD3 and anti-CD28 Abs in the presence of TGF-beta and IL-2. The obtained cells expressed high levels of CD25, CTLA-4, and Foxp3, and they were capable of suppressing in vitro proliferation of T cells from myasthenic rats in response to acetylcholine receptor, the major autoantigen in myasthenia. Administration of ex vivo-generated Treg cells to myasthenic rats inhibited the progression of experimental autoimmune MG and led to down-regulation of humoral acetylcholine receptor-specific responses, and to decreased IL-18 and IL-10 expression. The number of CD4(+)CD25(+) cells in the spleen of treated rats remained unchanged, but the subpopulation of CD4(+)CD25(+) cells expressing Foxp3 was significantly elevated. Our findings imply that Treg cells play a critical role in the control of myasthenia and could thus be considered as potential agents for the treatment of MG patients.
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Affiliation(s)
- Revital Aricha
- Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel
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30
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Sommer N, Tackenberg B, Hohlfeld R. The immunopathogenesis of myasthenia gravis. HANDBOOK OF CLINICAL NEUROLOGY 2008; 91:169-212. [PMID: 18631843 DOI: 10.1016/s0072-9752(07)01505-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Norbert Sommer
- Clinical Neuroimmunology Group, Philipps-University, Marburg, Germany
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Kalamida D, Poulas K, Avramopoulou V, Fostieri E, Lagoumintzis G, Lazaridis K, Sideri A, Zouridakis M, Tzartos SJ. Muscle and neuronal nicotinic acetylcholine receptors. FEBS J 2007; 274:3799-845. [PMID: 17651090 DOI: 10.1111/j.1742-4658.2007.05935.x] [Citation(s) in RCA: 216] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are integral membrane proteins and prototypic members of the ligand-gated ion-channel superfamily, which has precursors in the prokaryotic world. They are formed by the assembly of five transmembrane subunits, selected from a pool of 17 homologous polypeptides (alpha1-10, beta1-4, gamma, delta, and epsilon). There are many nAChR subtypes, each consisting of a specific combination of subunits, which mediate diverse physiological functions. They are widely expressed in the central nervous system, while, in the periphery, they mediate synaptic transmission at the neuromuscular junction and ganglia. nAChRs are also found in non-neuronal/nonmuscle cells (keratinocytes, epithelia, macrophages, etc.). Extensive research has determined the specific function of several nAChR subtypes. nAChRs are now important therapeutic targets for various diseases, including myasthenia gravis, Alzheimer's and Parkinson's diseases, and schizophrenia, as well as for the cessation of smoking. However, knowledge is still incomplete, largely because of a lack of high-resolution X-ray structures for these molecules. Nevertheless, electron microscopy studies on 2D crystals of nAChR from fish electric organs and the determination of the high-resolution X-ray structure of the acetylcholine binding protein (AChBP) from snails, a homolog of the extracellular domain of the nAChR, have been major steps forward and the data obtained have important implications for the design of subtype-specific drugs. Here, we review some of the latest advances in our understanding of nAChRs and their involvement in physiology and pathology.
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Affiliation(s)
- Dimitra Kalamida
- Department of Pharmacy, University of Patras, Rio Patras, Greece
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Fostieri E, Kostelidou K, Poulas K, Tzartos SJ. Recent advances in the understanding and therapy of myasthenia gravis. FUTURE NEUROLOGY 2006. [DOI: 10.2217/14796708.1.6.799] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Myasthenia gravis (MG) is a T-cell dependent autoimmune disease mediated by autoantibodies, which mainly target muscle nicotinic acetylcholine receptors (AChR) and cause loss of functional AChRs in the neuromuscular junction. Both MG and its major autoantigen are studied extensively, yet the etiology of the disease remains unclear, although it is known to be associated with the thymus. A genetic predisposition, combined with several unidentified environmental stimuli, likely creates a favorable milieu in which the disease can appear. Current research focusses on elucidating the cellular and molecular pathways of immune dysregulation, which underly MG outburst and progression. Considerable progress has been made concerning the involvement of the thymus, the identification of impaired mechanisms of immune control and the B–T-cell interaction in MG pathogenesis, while the role of chemokines arises as an intriguing new puzzle. Recent findings fueled the development of novel therapeutic approaches with some encouraging, although preliminary, results. This review summarizes recent achievements in the fields of both basic research and therapeutics.
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Affiliation(s)
- Efrosini Fostieri
- Hellenic Pasteur Institute, Department of Biochemistry, 127 Vas. Sofias Avenue, 11521 Athens, Greece
| | - Kalliopi Kostelidou
- Hellenic Pasteur Institute, Department of Biochemistry, 127 Vas. Sofias Avenue 11521 Athens, Greece
| | | | - Socrates J Tzartos
- Hellenic Pasteur Institute, Department of Biochemistry, 127 Vas. Sofias Avenue, 11521 Athens, Greece and, Department of Pharmacy, University of Patras, 26504 Patras, Greece
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Abstract
Myasthenia gravis (MG) is an autoimmune disease mediated by antibodies to nicotinic acetylcholine receptor (AChR) interfering with the neuromuscular transmission. Experimental autoimmune MG serves as an excellent animal model to study possible therapeutic modalities for MG. This review will focus on the different ways to turn off the autoimmune response to AChR, which results in suppression of myasthenia. This paper will describe the use of fragments or peptides derived from the AChR, antigen-presenting cells and anti-T cell receptor antibodies, and will discuss the underlying mechanisms of action. Finally, the authors propose new promising therapeutic prospects, including treatment based on the modulation of regulatory T cells, which have recently been found to be functionally defective in MG patients.
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Affiliation(s)
- Sonia Berrih-Aknin
- CNRS UMR 8078, Universite Paris Sud, IPSC Hôpital Marie Lannelongue, 133 Avenue de la Résistance, 92350 Le Plessis Robinson, France Tel: +33 1 45 37 15 51; Fax: +33 1 46 30 45 64; E-mail:
- The Weizmann Institute of Science, Department of Immunology, Rehovot 76100, Israel Tel: +972 8 934 2618; Fax: +972 8 934 4141; E-mail:
| | - Sara Fuchs
- The Weizmann Institute of Science, Department of Immunology, Rehovot 76100, Israel Tel: +972 8 934 2618; Fax: +972 8 934 4141; E-mail:
| | - Miriam C Souroujon
- The Weizmann Institute of Science, Department of Immunology, Rehovot 76100, Israel Tel: +972 8 934 2618; Fax: +972 8 934 4141; E-mail:
- The Open University of Israel, Raanana 43104, Israel Tel: +972 9 778 1758; E-mail:
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Aricha R, Feferman T, Souroujon MC, Fuchs S. Overexpression of phosphodiesterases in experimental autoimmune myasthenia gravis: suppression of disease by a phosphodiesterase inhibitor. FASEB J 2005; 20:374-6. [PMID: 16365386 DOI: 10.1096/fj.05-4909fje] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Myasthenia gravis (MG) and experimental autoimmune MG (EAMG) are T cell-dependent antibody-mediated autoimmune disorders, in which the nicotinic acetylcholine receptor (AChR) is the major autoantigen. DNA microarray analysis revealed increased levels of several phosphodiesterase (PDE) subtypes in lymph node cells (LNC) and muscles of EAMG rats compared with healthy controls. Quantitative real-time PCR analysis indicated that EAMG is characterized by an increase of PDE subtypes 1, 3, 4, and 7 in LNC and of PDE subtypes 2, 3, 4, and 7 in muscles. Pentoxifylline (PTX), a general PDE inhibitor, inhibited the progression of EAMG when treatment started at either the acute or chronic stages of disease. This suppression was associated with down-regulation of humoral and cellular AChR-specific responses, as well as down-regulation of PDE4, TNF-alpha, IL-18, IL-12, and IL-10 in LNC and of PDEs 1, 4, 7, and TNF-alpha in muscles. The expression of Foxp3, a transcription factor essential for CD4+CD25+ regulatory T cell function, was increased in splenocytes although the number of these cells remained unchanged. PTX also reduced the expression of the endopeptidase cathepsin-l, a marker of muscle damage, in EAMG muscles. This study demonstrates the involvement of PDE regulation in EAMG pathogenesis and suggests that PDE inhibitors may be considered for immunotherapy of MG.
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Affiliation(s)
- Revital Aricha
- Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel
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35
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Feferman T, Maiti PK, Berrih-Aknin S, Bismuth J, Bidault J, Fuchs S, Souroujon MC. Overexpression of IFN-Induced Protein 10 and Its Receptor CXCR3 in Myasthenia Gravis. THE JOURNAL OF IMMUNOLOGY 2005; 174:5324-31. [PMID: 15843529 DOI: 10.4049/jimmunol.174.9.5324] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Myasthenia gravis (MG) and its animal model, experimental autoimmune MG (EAMG), are autoimmune disorders in which the acetylcholine receptor (AChR) is the major autoantigen. Microarray technology was used to identify new potential drug targets for treatment of myasthenia that would reduce the need for the currently used nonspecific immunosuppression. The chemokine IFN-gamma-inducible protein 10 (IP-10; CXCL10), a CXC chemokine, and its receptor, CXCR3, were found to be overexpressed in lymph node cells of EAMG rats. Quantitative real-time PCR confirmed these findings and revealed up-regulated mRNA levels of another chemoattractant that activates CXCR3, monokine induced by IFN-gamma (Mig; CXCL9). TNF-alpha and IL-1beta, which act synergistically with IFN-gamma to induce IP-10, were also up-regulated. These up-regulations were observed in immune response effector cells, namely, lymph node cells, and in the target organ of the autoimmune attack, the muscle of myasthenic rats, and were significantly reduced after suppression of EAMG by mucosal tolerance induction with an AChR fragment. The relevance of IP-10/CXCR3 signaling in myasthenia was validated by similar observations in MG patients. A significant increase in IP-10 and CXCR3 mRNA levels in both thymus and muscle was observed in myasthenic patients compared with age-matched controls. CXCR3 expression in PBMC of MG patients was markedly increased in CD4(+), but not in CD8(+), T cells or in CD19(+) B cells. Our results demonstrate a positive association of IP-10/CXCR3 signaling with the pathogenesis of EAMG in rats as well as in human MG patients.
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MESH Headings
- Adolescent
- Adult
- Aged
- Animals
- Cell Adhesion Molecules/biosynthesis
- Chemokine CXCL10
- Chemokines, CXC/biosynthesis
- Chemokines, CXC/genetics
- Chemokines, CXC/metabolism
- Female
- Gene Expression Profiling/methods
- Humans
- Interferon-gamma/physiology
- Lymph Nodes/immunology
- Lymph Nodes/metabolism
- Male
- Middle Aged
- Muscle, Skeletal/immunology
- Muscle, Skeletal/metabolism
- Myasthenia Gravis/genetics
- Myasthenia Gravis/immunology
- Myasthenia Gravis/pathology
- Myasthenia Gravis, Autoimmune, Experimental/genetics
- Myasthenia Gravis, Autoimmune, Experimental/immunology
- Myasthenia Gravis, Autoimmune, Experimental/prevention & control
- Oligonucleotide Array Sequence Analysis
- Protein Subunits/administration & dosage
- Protein Subunits/immunology
- Rats
- Rats, Inbred Lew
- Receptors, CXCR3
- Receptors, Chemokine/biosynthesis
- Receptors, Chemokine/genetics
- Receptors, Chemokine/metabolism
- Receptors, Nicotinic/administration & dosage
- Receptors, Nicotinic/immunology
- Up-Regulation/immunology
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Affiliation(s)
- Tali Feferman
- Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel
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36
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Pachner AR. Antigen-specific immunotherapy in myasthenia gravis: failed promise and new hope. J Neuroimmunol 2004; 152:vii-viii. [PMID: 15223253 DOI: 10.1016/j.jneuroim.2004.04.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2004] [Indexed: 11/24/2022]
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