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Wang S, Breskovska I, Gandhy S, Punga AR, Guptill JT, Kaminski HJ. Advances in autoimmune myasthenia gravis management. Expert Rev Neurother 2018; 18:573-588. [PMID: 29932785 PMCID: PMC6289049 DOI: 10.1080/14737175.2018.1491310] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Myasthenia gravis (MG) is an autoimmune neuromuscular disorder with no cure and conventional treatments limited by significant adverse effects and variable benefit. In the last decade, therapeutic development has expanded based on improved understanding of autoimmunity and financial incentives for drug development in rare disease. Clinical subtypes exist based on age, gender, thymic pathology, autoantibody profile, and other poorly defined factors, such as genetics, complicate development of specific therapies. Areas covered: Clinical presentation and pathology vary considerably among patients with some having weakness limited to the ocular muscles and others having profound generalized weakness leading to respiratory insufficiency. MG is an antibody-mediated disorder dependent on autoreactive B cells which require T-cell support. Treatments focus on elimination of circulating autoantibodies or inhibition of effector mechanisms by a broad spectrum of approaches from plasmapheresis to B-cell elimination to complement inhibition. Expert commentary: Standard therapies and those under development are disease modifying and not curative. As a rare disease, clinical trials are challenged in patient recruitment. The great interest in development of treatments specific for MG is welcome, but decisions will need to be made to focus on those that offer significant benefits to patients.
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Affiliation(s)
- Shuhui Wang
- Department of Neurology, George Washington University, Washington DC 20008
| | - Iva Breskovska
- Department of Neurology, George Washington University, Washington DC 20008
| | - Shreya Gandhy
- Department of Neurology, George Washington University, Washington DC 20008
| | - Anna Rostedt Punga
- Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Uppsala, Sweden
| | - Jeffery T. Guptill
- Department of Neurology, Duke University Medical Center, Durham, North Carolina, USA
| | - Henry J. Kaminski
- Department of Neurology, George Washington University, Washington DC 20008
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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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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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Díaz-Manera J, Rojas García R, Illa I. Treatment strategies for myasthenia gravis: an update. Expert Opin Pharmacother 2012; 13:1873-83. [DOI: 10.1517/14656566.2012.705831] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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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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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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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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10
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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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11
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Maiti PK, Feferman T, Im SH, Souroujon MC, Fuchs S. Immunosuppression of rat myasthenia gravis by oral administration of a syngeneic acetylcholine receptor fragment. J Neuroimmunol 2004; 152:112-20. [PMID: 15223243 DOI: 10.1016/j.jneuroim.2004.04.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2003] [Revised: 03/19/2004] [Accepted: 04/21/2004] [Indexed: 11/21/2022]
Abstract
A syngeneic rat recombinant fragment of the extracellular domain of the acetylcholine receptor (AChR) alpha-subunit (Ralpha1-205), administered orally, suppresses ongoing experimental autoimmune myasthenia gravis (EAMG) in rats. The underlying mechanism is a shift from Th1 to Th2 regulation as evidenced by downregulated mRNA expression levels of IFN-gamma and TNF-alpha, upregulated IL-10, changes in anti-AChR IgG isotypes and diminished Th1 signaling via CD28/CTLA-4:B7. Unlike the xenogeneic fragment, the syngeneic Ralpha1-205 does not induce elevation in TGF-beta and elicitation of autoregulatory cells. The ability to suppress EAMG by a non-immunogenic syngeneic fragment of AChR is encouraging and may in the future be applied for the treatment of myasthenia gravis in humans.
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MESH Headings
- Animals
- Disease Models, Animal
- Female
- Humans
- Immune Tolerance
- Immunosuppression Therapy
- Interferon-gamma/biosynthesis
- Interleukin-10/biosynthesis
- Myasthenia Gravis, Autoimmune, Experimental/immunology
- Myasthenia Gravis, Autoimmune, Experimental/therapy
- Peptides/immunology
- RNA, Messenger/analysis
- Rats
- Rats, Inbred Lew
- Receptors, Nicotinic/immunology
- Reverse Transcriptase Polymerase Chain Reaction
- Th1 Cells/immunology
- Th2 Cells/immunology
- Transplantation, Heterologous
- Transplantation, Isogeneic
- Tumor Necrosis Factor-alpha/biosynthesis
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Affiliation(s)
- Prasanta K Maiti
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
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12
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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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Im SH, Barchan D, Souroujon MC, Fuchs S. Role of tolerogen conformation in induction of oral tolerance in experimental autoimmune myasthenia gravis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:3599-605. [PMID: 11034361 DOI: 10.4049/jimmunol.165.7.3599] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We recently demonstrated that oral or nasal administration of recombinant fragments of the acetylcholine receptor (AChR) prevents the induction of experimental autoimmune myasthenia gravis (EAMG) and suppresses ongoing EAMG in rats. We have now studied the role of spatial conformation of these recombinant fragments in determining their tolerogenicity. Two fragments corresponding to the extracellular domain of the human AChR alpha-subunit and differing in conformation were tested: Halpha1-205 expressed with no fusion partner and Halpha1-210 fused to thioredoxin (Trx), and designated Trx-Halpha1-210. The conformational similarity of the fragments to intact AChR was assessed by their reactivity with alpha-bungarotoxin and with anti-AChR mAbs, specific for conformation-dependent epitopes. Oral administration of the more native fragment, Trx-Halpha1-210, at the acute phase of disease led to exacerbation of EAMG, accompanied by an elevation of AChR-specific humoral and cellular reactivity, increased levels of Th1-type cytokines (IL-2, IL-12), decreased levels of Th2 (IL-10)- or Th3 (TGF-beta)-type cytokines, and higher expression of costimulatory factors (CD28, CTLA4, B7-1, B7-2, CD40L, and CD40). On the other hand, oral administration of the less native fragments Halpha1-205 or denatured Trx-Halpha1-210 suppressed ongoing EAMG and led to opposite changes in the immunological parameters. It thus seems that native conformation of AChR-derived fragments renders them immunogenic and immunopathogenic and therefore not suitable for treatment of myasthenia gravis. Conformation of tolerogens should therefore be given careful attention when considering oral tolerance for treatment of autoimmune diseases.
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Affiliation(s)
- S H Im
- Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel
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14
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Abstract
Much progress has been made in the 26 years since initial studies of the first purified acetylcholine receptors (AChRs) led to the discovery that an antibody-mediated autoimmune response to AChRs causes the muscular weakness and fatigability characteristic of myasthenia gravis (MG) and its animal model, experimental autoimmune myasthenia gravis (EAMG). Now, the structure of muscle AChRs is much better known. Monoclonal antibodies to muscle AChRs, developed as model autoantibodies for studies of EAMG, were used for initial purifications of neuronal AChRs, and now many homologous subunits of neuronal nicotinic AChRs have been cloned. There is a basic understanding of the pathological mechanisms by which autoantibodies to AChRs impair neuromuscular transmission. Immunodiagnostic assays for MG are used routinely. Nonspecific approaches to immunosuppressive therapy have been refined. However, fundamental mysteries remain regarding what initiates and sustains the autoimmune response to muscle AChRs and how to specifically suppress this autoimmune response using a practical therapy. Many rare congenital myasthenic syndromes have been elegantly shown to result from mutations in muscle AChRs. These studies have provided insights into AChR structure and function as well as into the pathological mechanisms of these diseases. Evidence has been found for autoimmune responses even to some central nervous system neurotransmitter receptors, but only one neuronal AChR has so far been implicated in an autoimmune disease. Thus far, only two neuronal AChR mutations have been found to be associated with a rare form of epilepsy, but many more neuronal AChR mutations will probably be found to be associated with disease in the years ahead.
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Affiliation(s)
- J M Lindstrom
- Department of Neuroscience, Medical School of the University of Pennsylvania, Philadelphia, Pennsylvania 19104-6074, USA.
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Venkatesh N, Im SH, Balass M, Fuchs S, Katchalski-Katzir E. Prevention of passively transferred experimental autoimmune myasthenia gravis by a phage library-derived cyclic peptide. Proc Natl Acad Sci U S A 2000; 97:761-6. [PMID: 10639153 PMCID: PMC15404 DOI: 10.1073/pnas.97.2.761] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many pathogenic antibodies in myasthenia gravis (MG) and its animal model, experimental autoimmune MG (EAMG), are directed against the main immunogenic region (MIR) of the acetylcholine receptor (AcChoR). These antibodies are highly conformation dependent; hence, linear peptides derived from native receptor sequences are poor candidates for their immunoneutralization. We employed a phage-epitope library to identify peptide-mimotopes capable of preventing the pathogenicity of the anti-MIR mAb 198. We identified a 15-mer peptide (PMTLPENYFSERPYH) that binds specifically to mAb 198 and inhibits its binding to AcChoR. A 10-fold increase in the affinity of this peptide was achieved by incorporating flanking amino acid residues from the coat protein as present in the original phage library. This extended peptide (AEPMTLPENYFSERPYHPPPP) was constrained by the addition of cysteine residues on both ends of the peptide, thus generating a cyclic peptide that inhibited the binding of mAb 198 to AcChoR with a potency that is three orders of magnitude higher when compared with the parent library peptide. This cyclic peptide inhibited the in vitro binding of mAb 198 to AcChoR and prevented the antigenic modulation of AcChoR caused by mAb 198 in human muscle cell cultures. The cyclic peptide also reacted with several other anti-MIR mAbs and the sera of EAMG rats. In addition, this peptide blocked the ability of mAb 198 to passively transfer EAMG in rats. Further derivatization of the cyclic peptide may aid in the design of suitable synthetic mimotopes for modulation of MG.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/pharmacology
- Antibody Specificity
- Bacteriophages
- Binding, Competitive
- Epitopes/administration & dosage
- Epitopes/immunology
- Female
- Humans
- Immune Sera/immunology
- Immune Sera/metabolism
- Molecular Sequence Data
- Myasthenia Gravis/immunology
- Myasthenia Gravis/prevention & control
- Oligopeptides/administration & dosage
- Oligopeptides/metabolism
- Oligopeptides/pharmacology
- Peptide Library
- Peptides, Cyclic/administration & dosage
- Peptides, Cyclic/chemistry
- Peptides, Cyclic/immunology
- Protein Binding
- Rats
- Rats, Inbred Lew
- Receptors, Cholinergic/immunology
- Receptors, Cholinergic/metabolism
- Tumor Cells, Cultured/drug effects
- Tumor Cells, Cultured/immunology
- Tumor Cells, Cultured/metabolism
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Affiliation(s)
- N Venkatesh
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
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16
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Im SH, Barchan D, Fuchs S, Souroujon MC. Suppression of ongoing experimental myasthenia by oral treatment with an acetylcholine receptor recombinant fragment. J Clin Invest 1999; 104:1723-30. [PMID: 10606626 PMCID: PMC409886 DOI: 10.1172/jci8121] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Myasthenia gravis (MG) is an autoimmune disorder in which the nicotinic acetylcholine receptor (AChR) is the major autoantigen. In an attempt to develop an antigen-specific therapy for MG, we administered a nonmyasthenogenic recombinant fragment of AChR orally to rats. This fragment, corresponding to the extracellular domain of the human AChR alpha-subunit (Halpha1-205), protected rats from subsequently induced experimental autoimmune myasthenia gravis (EAMG) and suppressed ongoing EAMG when treatment was initiated during either the acute or chronic phases of disease. Prevention and suppression of EAMG were accompanied by a significant decrease in AChR-specific humoral and cellular responses. The underlying mechanism for the Halpha1-205-induced oral tolerance seems to be active suppression, mediated by a shift from a T-helper 1 (Th1) to a Th2/Th3 response. This shift was assessed by changes in the cytokine profile, a deviation of anti-AChR IgG isotypes from IgG2 to IgG1, and a suppressed AChR-specific delayed-type hypersensitivity response. Our results in experimental myasthenia suggest that oral administration of AChR-specific recombinant fragments may be considered for antigen-specific immunotherapy of myasthenia gravis.
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Affiliation(s)
- S H Im
- Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel
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17
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Baggi F, Andreetta F, Caspani E, Milani M, Longhi R, Mantegazza R, Cornelio F, Antozzi C. Oral administration of an immunodominant T-cell epitope downregulates Th1/Th2 cytokines and prevents experimental myasthenia gravis. J Clin Invest 1999; 104:1287-95. [PMID: 10545527 PMCID: PMC409818 DOI: 10.1172/jci7121] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/1999] [Accepted: 09/22/1999] [Indexed: 11/17/2022] Open
Abstract
The mucosal administration of the native antigen or peptide fragments corresponding to immunodominant regions is effective in preventing or treating several T cell-dependent models of autoimmune disease. No data are yet available on oral tolerance with immunodominant T-cell peptides in experimental autoimmune myasthenia gravis (EAMG), an animal model of B cell-dependent disease. We report that oral administration of the T-cell epitope alpha146-162 of the Torpedo californica acetylcholine receptor (TAChR) alpha-subunit suppressed T-cell responses to AChR and ameliorated the disease in C57Bl/6 (B6) mice. Protection from EAMG was associated with reduced serum Ab's to mouse AChR and reduced AChR loss in muscle. The effect of Talpha146-162 feeding was specific; treatment with a control peptide did not affect EAMG manifestations. The protective effect induced by peptide Talpha146-162 was mediated by reduced production of IFN-gamma, IL-2, and IL-10 by TAChR-reactive cells, suggesting T-cell anergy. TGF-beta-secreting Th3 cells did not seem to be involved in tolerance induction. We therefore demonstrate that feeding a single immunodominant epitope can prevent an Ab-mediated experimental model of autoimmune disease.
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Affiliation(s)
- F Baggi
- Department of Neuromuscular Diseases, National Neurological Institute "C. Besta," 20133 Milan, Italy
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18
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Barchan D, Souroujon MC, Im SH, Antozzi C, Fuchs S. Antigen-specific modulation of experimental myasthenia gravis: nasal tolerization with recombinant fragments of the human acetylcholine receptor alpha-subunit. Proc Natl Acad Sci U S A 1999; 96:8086-91. [PMID: 10393952 PMCID: PMC22192 DOI: 10.1073/pnas.96.14.8086] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Myasthenia gravis (MG) and experimental autoimmune myasthenia gravis (EAMG) are antibody-mediated autoimmune diseases in which the nicotinic acetylcholine receptor (AcChoR) is the major autoantigen. The immune response in these diseases is heterogeneous and is directed to a wide variety of T and B cell epitopes of AcChoR. Candidate molecules for specific immunotherapy of MG should, therefore, have a broad specificity. We used recombinant fragments of the human AcChoR, encompassing the extracellular domain of the alpha-subunit, or shorter fragments derived from it, in experiments to modulate EAMG. We have demonstrated that intranasal administration of these recombinant fragments, which represent a major portion of epitopes involved in MG, prevents the induction of EAMG in rats and immunosuppresses an ongoing disease, as assessed by clinical symptoms, weight loss, and muscle AcChoR content. These effects on EAMG were accompanied by a marked reduction in the proliferative T-cell response and IL-2 production in response to AcChoR, in reduced anti-self AcChoR antibody titers and in an isotype switch of AcChoR-specific antibodies, from IgG2 to IgG1. We conclude that nasal tolerance induced by appropriate recombinant fragments of human AcChoR is effective in suppressing EAMG and might possibly be considered as a therapeutic modality for MG.
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Affiliation(s)
- D Barchan
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
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19
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Barchan D, Asher O, Tzartos SJ, Fuchs S, Souroujon MC. Modulation of the anti-acetylcholine receptor response and experimental autoimmune myasthenia gravis by recombinant fragments of the acetylcholine receptor. Eur J Immunol 1998; 28:616-24. [PMID: 9521072 DOI: 10.1002/(sici)1521-4141(199802)28:02<616::aid-immu616>3.0.co;2-i] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Myasthenia gravis (MG) is a neuromuscular disorder of man caused by a humoral response to the acetylcholine receptor (AChR). Most of the antibodies in MG and in experimental autoimmune myasthenia gravis (EAMG) are directed to the extracellular portion of the AChR alpha subunit, and within it, primarily to the main immunogenic region (MIR). We have cloned and expressed recombinant fragments, corresponding to the entire extracellular domain of the AChR alpha subunit (H alpha1-210), and to portions of it that encompass either the MIR (H alpha1-121) or the ligand binding site of AChR (H alpha122-210), and studied their ability to interfere with the immunopathological anti-AChR response in vitro and in vivo. All fragments were expressed as fusion proteins with glutathione S-transferase. Fragments H alpha1-121 and H alpha1-210 protected AChR in TE671 cells against accelerated degradation induced by the anti-MIR monoclonal antibody (mAb)198 in a dose-dependent manner. Moreover, these fragments had a similar effect on the antigenic modulation of AChR by other anti-MIR mAb and by polyclonal rat anti-AChR antibodies. Fragments H alpha1-121 and H alpha1-210 were also able to modulate in vivo muscle AChR loss and development of clinical symptoms of EAMG, passively transferred to rats by mAb 198. Fragment H alpha122-210 did not have such a protective activity. Our results suggest that the appropriate recombinant fragments of the human AChR may be employed in the future for antigen-specific therapy of myasthenia.
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Affiliation(s)
- D Barchan
- Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel
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Krolick KA, Thompson PA, Zoda TE, Yeh TM. Influence of immunological fine-specificity on the induction of experimental myasthenia gravis. Ann N Y Acad Sci 1993; 681:179-97. [PMID: 7689305 DOI: 10.1111/j.1749-6632.1993.tb22886.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- K A Krolick
- Department of Microbiology, University of Texas Health Science Center, San Antonio 78284
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Affiliation(s)
- M H De Baets
- Department of Immunology, State University of Limburg, Maastricht, The Netherlands
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Asher O, Neumann D, Fuchs S. Increased levels of acetylcholine receptor alpha-subunit mRNA in experimental autoimmune myasthenia gravis. FEBS Lett 1988; 233:277-81. [PMID: 3260196 DOI: 10.1016/0014-5793(88)80442-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
To gain insight into the regulatory mechanisms underlying the blockade and loss of acetylcholine receptor (AChR) in myasthenia, we have followed AChR alpha-subunit mRNA levels in leg muscles of myasthenic and normal rabbits and rats. Northern blots of RNA preparations from normal and myasthenic animals were hybridized with a mouse AChR alpha-subunit cDNA probe. Our experiments indicate a specific increase (4-7-fold) in the levels of alpha-subunit mRNA in animals with experimental autoimmune myasthenia gravis (EAMG), in comparison with control animals. Actin mRNA levels were essentially unchanged. Our results thus suggest that EAMG is accompanied by an increased level of AChR gene transcription.
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Affiliation(s)
- O Asher
- Department of Chemical Immunology, Weizmann Institute of Science, Rehovot, Israel
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Fuchs S, Neumann D, Safran A, Souroujon M, Barchan D, Fridkin M, Gershoni JM, Mantegazza R, Pizzighella S. Synthetic peptides and their antibodies in the analysis of the acetylcholine receptor. Ann N Y Acad Sci 1987; 505:256-71. [PMID: 2446550 DOI: 10.1111/j.1749-6632.1987.tb51295.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- S Fuchs
- Department of Chemical Immunology, Weizmann Institute of Science, Rehovot, Israel
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Neumann D, Barchan D, Fridkin M, Fuchs S. Analysis of ligand binding to the synthetic dodecapeptide 185-196 of the acetylcholine receptor alpha subunit. Proc Natl Acad Sci U S A 1986; 83:9250-3. [PMID: 3466185 PMCID: PMC387113 DOI: 10.1073/pnas.83.23.9250] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
A synthetic dodecapeptide corresponding to residues 185-196 of the Torpedo acetylcholine receptor alpha subunit, which contains the adjacent cysteine residues at positions 192 and 193, was recently shown by us to contain the essential elements for alpha-bungarotoxin binding. In the present study, we have used Sepharose-linked peptides for quantitative analysis of the cholinergic binding properties of this and other synthetic peptides. Sepharose-linked peptides corresponding to residues 1-20, 126-143, 143-158, 169-181, 185-196, 193-210, and 394-409 of the alpha subunit of Torpedo acetylcholine receptor, as well as a peptide corresponding to residues 185-196 of the alpha subunit of human acetylcholine receptor, were tested for their toxin-binding capacity. Of these immobilized peptides, only peptide 185-196 of the Torpedo acetylcholine receptor bound toxin significantly, thus verifying that this synthetic peptide contains essential components of the receptor toxin-binding site. Analysis of toxin binding to the peptide yielded a dissociation constant of 3.5 X 10(-5) M. This binding was inhibited by various cholinergic ligands. The inhibition potency obtained was alpha-bungarotoxin greater than Naja naja siamensis toxin greater than d-tubocurarine greater than decamethonium greater than acetylcholine greater than carbamoylcholine. This pharmacological profile resembles that of the nicotinic acetylcholine receptor and therefore suggests that the synthetic dodecapeptide also includes the neurotransmitter binding site. Reduction and carboxymethylation of the cysteine residues on peptide 185-196 inhibit its capacity to bind toxin, demonstrating that an intact disulfide is required for toxin binding. A decrease in toxin binding was also obtained following chemical modification of the tryptophan residue at position 187, thus implying its possible involvement in toxin binding. The failure to detect binding of toxin to the corresponding human sequence 185-196, in which the tryptophan residue is replaced by serine, supports this hypothesis.
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Souroujon MC, Fuchs S. Idiotypes and anti-idiotypes in experimental autoimmune myasthenia gravis. Ann N Y Acad Sci 1986; 475:81-93. [PMID: 3491567 DOI: 10.1111/j.1749-6632.1986.tb20858.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Bogen S, Mozes E, Fuchs S. Induction of acetylcholine receptor-specific suppression. An in vitro model of antigen-specific immunosuppression in myasthenia gravis. J Exp Med 1984; 159:292-304. [PMID: 6198424 PMCID: PMC2187190 DOI: 10.1084/jem.159.1.292] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
This report describes the in vivo and in vitro induction of murine (AChR)-specific suppressor T cells (Ts) and T cell factors (TsF), and the development of an appropriate assay system for their measurement. The assay described is based on the in vitro Mishell-Dutton culture system. Using this assay, it was shown that the AChR-specific helper cell is an Lyt-2- radiosensitive T cell. Moreover, the proliferating cell measured in the lymphocyte transformation assay was shown to provide AChR-specific T cell help. In vivo induction of Ts cells is achieved by injection of soluble AChR; potent AChR-specific suppression is found in the spleen 1 wk later. In vitro induction of Ts cells involves the primary education of naive splenocytes by culturing them with high concentrations of AChR. Both the in vivo- and in vitro-induced Ts cells were shown to secrete AChR-specific factors that mediate their suppressive effects. The possibility of specifically suppressing the AChR-immune response may be of a particular clinical importance since the AChR is the target autoantigen in the neuromuscular autoimmune disease myasthenia gravis.
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Fuchs S, Bartfeld D, Mochly-Rosen D, Souroujon M, Feingold C. Acetylcholine receptor: molecular dissection and monoclonal antibodies in the study of experimental myasthenia. Ann N Y Acad Sci 1981; 377:110-24. [PMID: 6176165 DOI: 10.1111/j.1749-6632.1981.tb33727.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Berman PW, Patrick J, Heinemann S, Klier FG, Steinbach JH. Factors affecting the susceptibility of different strains of mice to experimental myasthenia gravis. Ann N Y Acad Sci 1981; 377:237-57. [PMID: 6951476 DOI: 10.1111/j.1749-6632.1981.tb33736.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Mice immunized with purified AChR (T. californica) invariably form anti-AChR antibodies and often develop a condition of extreme muscular weakness and flaccid paralysis. Pharmacological, physiological, and ultrastructural studies indicate that the pathophysiology of EMG in the mouse closely resembles that of human MG. The single episode of muscular weakness typically found in mouse EMG differs from the acute phase of rat EMG in that macrophages and other phagocytes do not appear to play an active role in the destruction of the neuromuscular junction. The frequency of paralysis in mice immunized with AChR is highly strain dependent and is not attributable to polymorphisms with respect to susceptibility to cholinergic blockade. The incidence of paralysis does not correlate with the magnitude of the humoral response to either T. californica or mouse AChR. Because both paralyzed and nonparalyzed mice form antibodies which are able to increase the rate of both junctional and extrajunctional AChR degradation, the mere presence of antibodies reactive with cell surface antigenic determinants of AChR is not sufficient for the induction of paralysis. While it is still possible that antibody-induced degradation of AChR may be necessary for the induction of paralysis, these studies rule out the possibility that antigenic modulation of AChR is sufficient to account for the induction of paralysis in mouse EMG. In the present studies alleles of the two loci were identified which significantly effect the probability with which mice immunized with AChR can be expected to become paralyzed, the MHC and the IgCH region. Because one genotype, H-2b, Ig-1b segregated with high susceptibility to EMG in four strains derived from three dissimilar backgrounds, these studies strongly suggest that susceptibility to the development of paralysis is a heritable trait determined by regions of the mouse genome which regulate immune responsiveness.
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Fuchs S, Schmidt-Hopfeld I, Tridente G, Tarrab-Hazdai R. Thymic lymphocytes bear a surface antigen which cross-reacts with acetylcholine receptor. Nature 1980; 287:162-4. [PMID: 7001247 DOI: 10.1038/287162a0] [Citation(s) in RCA: 85] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Acetylcholine receptor (AChR) is a major antigen in the neuromuscular disease myasthenia gravis and it is clear today that the basic defect in this disease is brought about by an autoimmune attack on acetylcholine receptors at the neuromuscular junctions. The involvement of the thymus and its role in myasthenia have been widely investigated but are still poorly understood. A high incidence of thymic abnormalities is observed in patients with myasthenia and thymectomy is beneficial in many cases. Immunological studies have demonstrated the presence of humoral as well as cellular immune responses towards thymic tissues in myasthenic patients. There were also some reports that animals immunized with thymic extracts develop a partial defect in neuromuscular transmission. In spite of all these observations, the nature and origin of the association between the thymus and the neuromuscular junction in myasthenia gravis are still not known. We have previously demonstrated an immunological cross-reactivity, both humoral and cellular, between a thymic component and AChR; such a cross-reactivity could provide a molecular explanation for the involvement of the thymus in myasthenia gravis. In this study, we demonstrate, by using immunofluorescence and radioimmunological techniques, that thymic lymphocytes bear a surface antigen which binds specifically to antibodies against nicotinic AChR and is thus defined as an 'AChR-like' antigen. A preliminary report of this study has been published.
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Tarrab-Hazdai R, Schmidt-Sole Y, Mochly-Rosen D, Fuchs S. Modification of acetylcholine receptor: chemical and immunological characterization of polyalanyl acetylcholine receptor. FEBS Lett 1980; 118:35-8. [PMID: 6157569 DOI: 10.1016/0014-5793(80)81212-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Fuchs S, Bartfeld D, Eshhar Z, Feingold C, Mochly-Rosen D, Novick D, Schwartz M, Tarrab-Hazdai R. Immune regulation of experimental myasthenia. J Neurol Neurosurg Psychiatry 1980; 43:634-43. [PMID: 7400824 PMCID: PMC490630 DOI: 10.1136/jnnp.43.7.634] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Experimental autoimmune myasthenia gravis (EAMG) is an appropriate model for studying the molecular origin, immunological mechanism and regulation of myasthenia gravis. Several approaches are being utilised for the regulation of the immune response to AChR and for immunosuppression of EAMG: Corticosteriods and azathioprine can suppress EAMG concomitantly with suppression of immune responses to AChR. High dose cyclophosphamide treatment in mice facilitates the onset of EAMG and results in a selective suppression of the humoral response to AChR whereas the cellular response is enhanced. Specific immunosuppression of EAMG is achieved by using a nonmyasthenic, denatured AChR preparation which cross reacts with the intact receptor. Various degradations and modifications of AChR are being performed in order to identify the smallest molecular entity responsible for the myasthenic activity of AChR. Studies on specific monoclonal antibodies, anti-idiotypes, and on the effect of measles virus on EAMG are being described and their possible significance in regulating myasthenia are being discussed.
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Noguchi SA, Drachman DB, Adams RN, Hirsch RL. Lymphocyte responsiveness to acetylcholine receptor in rats with experimental autoimmune myasthenia gravis. Ann Neurol 1980; 8:32-7. [PMID: 7406445 DOI: 10.1002/ana.410080105] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We examined the time course of lymphocyte responsiveness to acetylcholine receptor (AChR) in rats with experimental autoimmune myasthenia gravis (EAMG). Rats were immunized with purified torpedo AChR. At intervals of one to eight weeks later, lymphocytes from the lymph nodes and spleen were cultured with purified torpedo AChR and rat muscle extract containing AChR. Lymphocyte responsiveness (stimulation index) was determined from uptake of 3H-labeled thymidine by the cultured cells. The response of lymphocytes to torpedo antigen began earlier and rose more rapidly than that to the homologous (rat) antigen. Lymph node cells responded more promptly than spleen lymphocytes. The stimulation indexes peaked at four to six weeks while antibodies to both antigen continued to rise. Delineation of this pattern of lymphocyte responsiveness sheds further light on the pathogenesis of the autoimmune response in EAMG and will be useful in the future design of immunotherapeutic strategies.
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Moshly-Rosen D, Fuchs S, Eshhar Z. Monoclonal antibodies against defined determinants of acetylcholine receptor. FEBS Lett 1979; 106:389-92. [PMID: 91535 DOI: 10.1016/0014-5793(79)80538-4] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Bartfeld D, Fuchs S. Fractionation of antibodies to acetylcholine receptor according to antigenic specificity. FEBS Lett 1979; 105:303-6. [PMID: 90624 DOI: 10.1016/0014-5793(79)80635-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Yowell RL, Araneo BA, Miller A, Sercarz EE. Amputation of a suppressor determinant on lysozyme reveals underlying T-cell reactivity to other determinants. Nature 1979; 279:70-1. [PMID: 88016 DOI: 10.1038/279070a0] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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