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Abstract
Thirty to fifty percent of patients with acetylcholine receptor (AChR) antibody (Ab)-negative myasthenia gravis (MG) have Abs to muscle specific kinase (MuSK) and are referred to as having MuSK-MG. MuSK is a 100 kD single-pass post-synaptic transmembrane receptor tyrosine kinase crucial to the development and maintenance of the neuromuscular junction. The Abs in MuSK-MG are predominantly of the IgG4 immunoglobulin subclass. MuSK-MG differs from AChR-MG, in exhibiting more focal muscle involvement, including neck, shoulder, facial and bulbar-innervated muscles, as well as wasting of the involved muscles. MuSK-MG is highly associated with the HLA DR14-DQ5 haplotype and occurs predominantly in females with onset in the fourth decade of life. Some of the standard treatments of AChR-MG have been found to have limited effectiveness in MuSK-MG, including thymectomy and cholinesterase inhibitors. Therefore, current treatment involves immunosuppression, primarily by corticosteroids. In addition, patients respond especially well to B cell depletion agents, e.g., rituximab, with long-term remissions. Future treatments will likely derive from the ongoing analysis of the pathogenic mechanisms underlying this disease, including histologic and physiologic studies of the neuromuscular junction in patients as well as information derived from the development and study of animal models of the disease.
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Affiliation(s)
| | - David P. Richman
- Department of Neurology, University of California, Davis, Davis, CA, United States
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Zhang L, Shen H, Gong Y, Pang X, Yi M, Guo L, Li J, Arroyo S, Lu X, Ovchinnikov S, Cheng G, Liu X, Jiang X, Feng S, Deng H. Development of a dual-functional conjugate of antigenic peptide and Fc-III mimetics (DCAF) for targeted antibody blocking. Chem Sci 2019; 10:3271-3280. [PMID: 30996912 PMCID: PMC6429600 DOI: 10.1039/c8sc05273e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 01/28/2019] [Indexed: 01/12/2023] Open
Abstract
Targeted antibody blocking enables characterization of binding sites on immunoglobulin G (IgG), and can efficiently eliminate harmful antibodies from organisms. In this report, we present a novel peptide-denoted as a dual-functional conjugate of antigenic peptide and Fc-III mimetics (DCAF)-for targeted blocking of antibodies. Synthesis of DCAF was achieved by native chemical ligation, and the molecule consists of three functional parts: a specific antigenic peptide, a linker and the Fc-III mimetic peptide, which has a high affinity toward the Fc region of IgG molecules. We demonstrate that DCAF binds the cognate antibody with high selectivity by simultaneously binding to the Fab and Fc regions of IgG. Animal experiments revealed that DCAF molecules diminish the antibody-dependent enhancement effect in a dengue virus infection model, and rescue the acetylcholine receptor by inhibiting the complement cascade in a myasthenia gravis model. These results suggest that DCAFs could have utility in the development of new therapeutics against harmful antibodies.
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Affiliation(s)
- Lin Zhang
- MOE Key Laboratory of Bioinformatics , Center for Synthetic and Systems Biology , School of Life Sciences , Tsinghua University , Beijing , China .
| | - Hao Shen
- Institute for Protein Design , Department of Biochemistry , University of Washington , Seattle , WA , USA
| | - Yiyi Gong
- Central Research Laboratory , Peking Union Medical College Hospital , Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing , China
| | - Xiaojing Pang
- Tsinghua-Peking Center for Life Sciences , School of Medicine , Tsinghua University , Beijing , China
| | - Meiqi Yi
- MOE Key Laboratory of Bioinformatics , Center for Synthetic and Systems Biology , School of Life Sciences , Tsinghua University , Beijing , China .
| | - Lin Guo
- MOE Key Laboratory of Bioinformatics , Center for Synthetic and Systems Biology , School of Life Sciences , Tsinghua University , Beijing , China .
| | - Jin Li
- MOE Key Laboratory of Bioinformatics , Center for Synthetic and Systems Biology , School of Life Sciences , Tsinghua University , Beijing , China .
| | - Sam Arroyo
- Department of Biological Sciences , University of Notre Dame , South Bend , IN , USA
| | - Xin Lu
- Department of Biological Sciences , University of Notre Dame , South Bend , IN , USA
| | - Sergey Ovchinnikov
- Institute for Protein Design , Department of Biochemistry , University of Washington , Seattle , WA , USA
| | - Gong Cheng
- Tsinghua-Peking Center for Life Sciences , School of Medicine , Tsinghua University , Beijing , China
| | - Xudong Liu
- Central Research Laboratory , Peking Union Medical College Hospital , Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing , China
| | - Xu Jiang
- Central Research Laboratory , Peking Union Medical College Hospital , Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing , China
| | - Shan Feng
- Mass Spectrometry Facility , Westlake Lake University , Hangzhou , Zhejiang Province , China .
| | - Haiteng Deng
- MOE Key Laboratory of Bioinformatics , Center for Synthetic and Systems Biology , School of Life Sciences , Tsinghua University , Beijing , China .
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Heterogeneity of auto-antibodies against nAChR in myasthenic serum and their pathogenic roles in experimental autoimmune myasthenia gravis. J Neuroimmunol 2018; 320:64-75. [PMID: 29759142 DOI: 10.1016/j.jneuroim.2018.04.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/23/2018] [Accepted: 04/23/2018] [Indexed: 11/20/2022]
Abstract
Many myasthenia gravis (MG) patients have auto-antibodies against the nicotinic acetylcholine receptor (nAChR), and monoclonal antibodies against the main immunogenic region (MIR) of nAChR can induce experimental autoimmune MG (EAMG). We investigated whether Fab fragment of MIR antibody (Fab35) could block the pathogenicity of polyclonal antibodies. Fab35 partially inhibited nAChR downmodulation, blocked EAMG serum-induced binding of polyclonal antibodies and complement deposition in vitro. Moreover, Fab35 did not ameliorate the EAMG serum-induced EAMG phenotype in rats. These results suggested that the EAMG serum possessed several different pathogenic antibodies that might be sufficient to induce the EAMG phenotype.
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Analysis of peripheral B cells and autoantibodies against the anti-nicotinic acetylcholine receptor derived from patients with myasthenia gravis using single-cell manipulation tools. PLoS One 2017; 12:e0185976. [PMID: 29040265 PMCID: PMC5645109 DOI: 10.1371/journal.pone.0185976] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 09/23/2017] [Indexed: 11/23/2022] Open
Abstract
The majority of patients with myasthenia gravis (MG), an organ-specific autoimmune disease, harbor autoantibodies that attack the nicotinic acetylcholine receptor (nAChR-Abs) at the neuromuscular junction of skeletal muscles, resulting in muscle weakness. Single cell manipulation technologies coupled with genetic engineering are very powerful tools to examine T cell and B cell repertoires and the dynamics of adaptive immunity. These tools have been utilized to develop mAbs in parallel with hybridomas, phage display technologies and B-cell immortalization. By applying a single cell technology and novel high-throughput cell-based binding assays, we identified peripheral B cells that produce pathogenic nAChR-Abs in patients with MG. Although anti-nAChR antibodies produced by individual peripheral B cells generally exhibited low binding affinity for the α-subunit of the nAChR and great sequence diversity, a small fraction of these antibodies bound with high affinity to native-structured nAChRs on cell surfaces. B12L, one such Ab isolated here, competed with a rat Ab (mAb35) for binding to the human nAChR and thus considered to recognize the main immunogenic region (MIR). By evaluating the Ab in in vitro cell-based assays and an in vivo rat passive transfer model, B12L was found to act as a pathogenic Ab in rodents and presumably in humans.These findings suggest that B cells in peripheral blood may impact MG pathogenicity. Our methodology can be applied not only to validate pathogenic Abs as molecular target of MG treatment, but also to discover and analyze Ab production systems in other human diseases.
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De Rosa L, Finetti F, Diana D, Di Stasi R, Auriemma S, Romanelli A, Fattorusso R, Ziche M, Morbidelli L, D’Andrea LD. Miniaturizing VEGF: Peptides mimicking the discontinuous VEGF receptor-binding site modulate the angiogenic response. Sci Rep 2016; 6:31295. [PMID: 27498819 PMCID: PMC4976335 DOI: 10.1038/srep31295] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 07/15/2016] [Indexed: 12/20/2022] Open
Abstract
The angiogenic properties of VEGF are mediated through the binding of VEGF to its receptor VEGFR2. The VEGF/VEGFR interface is constituted by a discontinuous binding region distributed on both VEGF monomers. We attempted to reproduce this discontinuous binding site by covalently linking into a single molecular entity two VEGF segments involved in receptor recognition. We designed and synthesized by chemical ligation a set of peptides differing in length and flexibility of the molecular linker joining the two VEGF segments. The biological activity of the peptides was characterized in vitro and in vivo showing a VEGF-like activity. The most biologically active mini-VEGF was further analyzed by NMR to determine the atomic details of its interaction with the receptor.
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Affiliation(s)
- Lucia De Rosa
- Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16, 80134, Napoli, Italy
| | - Federica Finetti
- Dipartimento di Scienze della Vita, Università di Siena, Via A. Moro 2, 53100 Siena, Italy
| | - Donatella Diana
- Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16, 80134, Napoli, Italy
| | - Rossella Di Stasi
- Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16, 80134, Napoli, Italy
| | - Sara Auriemma
- Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16, 80134, Napoli, Italy
| | - Alessandra Romanelli
- Dipartimento di Farmacia, Università di Napoli “Federico II”, via Mezzocannone 16, 80134, Napoli, Italy
| | - Roberto Fattorusso
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università di Napoli, via A. Vivaldi 43, 81100, Caserta, Italy
| | - Marina Ziche
- Dipartimento di Scienze della Vita, Università di Siena, Via A. Moro 2, 53100 Siena, Italy
| | - Lucia Morbidelli
- Dipartimento di Scienze della Vita, Università di Siena, Via A. Moro 2, 53100 Siena, Italy
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Morell SW, Trinh VB, Gudipati E, Friend A, Page NA, Agius MA, Richman DP, Fairclough RH. Structural characterization of the main immunogenic region of the Torpedo acetylcholine receptor. Mol Immunol 2013; 58:116-31. [PMID: 24333757 DOI: 10.1016/j.molimm.2013.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/06/2013] [Accepted: 11/07/2013] [Indexed: 11/27/2022]
Abstract
To develop antigen-specific immunotherapies for autoimmune diseases, knowledge of the molecular structure of targeted immunological hotspots will guide the production of reagents to inhibit and halt production of antigen specific attack agents. To this end we have identified three noncontiguous segments of the Torpedo nicotinic acetylcholine receptor (AChR) α-subunit that contribute to the conformationally sensitive immunological hotspot on the AChR termed the main immunogenic region (MIR): α(1-12), α(65-79), and α(110-115). This region is the target of greater than 50% of the anti-AChR Abs in serum from patients with myasthenia gravis (MG) and animals with experimental autoimmune myasthenia gravis (EAMG). Many monoclonal antibodies (mAbs) raised in one species against an electric organ AChR cross react with the neuromuscular AChR MIR in several species. Probing the Torpedo AChR α-subunit with mAb 132A, a disease inducing anti-MIR mAb raised against the Torpedo AChR, we have determined that two of the three MIR segments, α(1-12) and α(65-79), form a complex providing the signature components recognized by mAb 132A. These two segments straddle a third, α(110-115), that seems not to contribute specific side chains for 132A recognition, but is necessary for optimum antibody binding. This third segment appears to form a foundation upon which the three-dimensional 132A epitope is anchored.
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Affiliation(s)
- Stuart W Morell
- University of California, Davis School of Medicine, Department of Neurology, One Shields Avenue, 1515 Newton Court, Room 510C, Davis, CA 95616, United States; Biochemistry, Molecular, Cellular, and Developmental Biology Graduate Group of UC Davis, United States
| | - Vu B Trinh
- University of California, Davis School of Medicine, Department of Neurology, One Shields Avenue, 1515 Newton Court, Room 510C, Davis, CA 95616, United States; Biochemistry, Molecular, Cellular, and Developmental Biology Graduate Group of UC Davis, United States
| | - Eswari Gudipati
- Biochemistry, Siemens Healthcare Diagnostics, 5210 Pacific Concourse Drive, Los Angeles, CA 90045, United States
| | - Alexander Friend
- University of California, Davis School of Medicine, Department of Neurology, One Shields Avenue, 1515 Newton Court, Room 510C, Davis, CA 95616, United States
| | - Nelson A Page
- University of California, Davis School of Medicine, Department of Neurology, One Shields Avenue, 1515 Newton Court, Room 510C, Davis, CA 95616, United States; Department of Physics Graduate Program, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States
| | - Mark A Agius
- University of California, Davis School of Medicine, Department of Neurology, One Shields Avenue, 1515 Newton Court, Room 510C, Davis, CA 95616, United States; VANCHCS, 10535 Hospital Way, Mather, CA 95655, United States
| | - David P Richman
- University of California, Davis School of Medicine, Department of Neurology, One Shields Avenue, 1515 Newton Court, Room 510C, Davis, CA 95616, United States; Neurosciences Graduate Group of UC Davis, United States
| | - Robert H Fairclough
- University of California, Davis School of Medicine, Department of Neurology, One Shields Avenue, 1515 Newton Court, Room 510C, Davis, CA 95616, United States; Biochemistry, Molecular, Cellular, and Developmental Biology Graduate Group of UC Davis, United States; Biophysics Graduate Group of UC Davis, United States.
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