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Spagni G, Vincent A, Sun B, Falso S, Jacobson LW, Devenish S, Evoli A, Damato V. Serological Markers of Clinical Improvement in MuSK Myasthenia Gravis. NEUROLOGY(R) NEUROIMMUNOLOGY & NEUROINFLAMMATION 2024; 11:e200313. [PMID: 39250722 PMCID: PMC11385952 DOI: 10.1212/nxi.0000000000200313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
BACKGROUND AND OBJECTIVES In this retrospective longitudinal study, we aimed at exploring the role of (a) MuSK-immunoglobulin G (IgG) levels, (b) predominant MuSK-IgG subclasses, and (c) antibody affinity as candidate biomarkers of severity and outcomes in MuSK-MG, using and comparing different antibody testing techniques. METHODS Total MuSK-IgGs were quantified with radioimmunoassay (RIA), ELISA, flow cytometry, and cell-based assay (CBA) serial dilutions using HEK293 cells transfected with MuSK-eGFP. MuSK-IgG subclasses were measured by flow cytometry. SAffCon assay was used for determining MuSK-IgG affinity. RESULTS Forty-three serum samples were obtained at different time points from 20 patients with MuSK-MG (median age at onset: 48 years, interquartile range = 27.5-72.5; women, 16/20), with 9 of 20 (45%) treated with rituximab. A strong correlation between MuSK-IgG levels measured by flow cytometry and RIA titers was found (rs = 0.74, 95% CI 0.41-0.89, p = 0.0003), as well as a moderate correlation between CBA end-point titers and RIA titers (rs = 0.47, 95% CI 0.01-0.77, p = 0.0414). A significant correlation was found between MuSK-IgG flow cytometry levels and disease severity (rs = 0.39, 95% CI 0.06-0.64, p = 0.0175; mixed-effects model estimate: 2.296e-06, std. error: 1.024e-06, t = 2.243, p = 0.032). In individual patients, clinical improvement was associated with decrease in MuSK-IgG levels, as measured by either flow cytometry or CBA end-point titration. In all samples, MuSK-IgG4 was the most frequent isotype (mean ± SD: 90.95% ± 13.89). A significant reduction of MuSK-IgG4 and, to a lesser extent, of MuSK-IgG2, was seen in patients with favorable clinical outcomes. A similar trend was confirmed in the subgroup of rituximab-treated patients. In a single patient, MuSK-IgG affinity increased during symptom exacerbation (KD values: 62 nM vs 0.6 nM) while total MuSK-IgG and IgG4 levels remained stable, suggesting that affinity maturation may be a driver of clinical worsening. DISCUSSION Our data support the quantification of MuSK antibodies by flow cytometry. Through a multimodal investigational approach, we showed that total MuSK-IgG levels, MuSK-IgG4 and MuSK-IgG2 levels, and MuSK-IgG affinity may represent promising biomarkers of disease outcomes in MuSK-MG.
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Affiliation(s)
- Gregorio Spagni
- From the Department of Neuroscience (G.S., S.F., A.E.), Università Cattolica del Sacro Cuore, Rome, Italy; German Center for Neurodegenerative Diseases (DZNE) Berlin (G.S.), Berlin, Germany; Nuffield Department of Clinical Neurosciences (A.V., B.S., L.W.J.), University of Oxford; Fluidic Analytics Ltd (S.D.), The Paddocks Business Centre, Cambridge, United Kingdom; and Department of Neurosciences (V.D.), Drugs and Child Health, University of Florence, Italy
| | - Angela Vincent
- From the Department of Neuroscience (G.S., S.F., A.E.), Università Cattolica del Sacro Cuore, Rome, Italy; German Center for Neurodegenerative Diseases (DZNE) Berlin (G.S.), Berlin, Germany; Nuffield Department of Clinical Neurosciences (A.V., B.S., L.W.J.), University of Oxford; Fluidic Analytics Ltd (S.D.), The Paddocks Business Centre, Cambridge, United Kingdom; and Department of Neurosciences (V.D.), Drugs and Child Health, University of Florence, Italy
| | - Bo Sun
- From the Department of Neuroscience (G.S., S.F., A.E.), Università Cattolica del Sacro Cuore, Rome, Italy; German Center for Neurodegenerative Diseases (DZNE) Berlin (G.S.), Berlin, Germany; Nuffield Department of Clinical Neurosciences (A.V., B.S., L.W.J.), University of Oxford; Fluidic Analytics Ltd (S.D.), The Paddocks Business Centre, Cambridge, United Kingdom; and Department of Neurosciences (V.D.), Drugs and Child Health, University of Florence, Italy
| | - Silvia Falso
- From the Department of Neuroscience (G.S., S.F., A.E.), Università Cattolica del Sacro Cuore, Rome, Italy; German Center for Neurodegenerative Diseases (DZNE) Berlin (G.S.), Berlin, Germany; Nuffield Department of Clinical Neurosciences (A.V., B.S., L.W.J.), University of Oxford; Fluidic Analytics Ltd (S.D.), The Paddocks Business Centre, Cambridge, United Kingdom; and Department of Neurosciences (V.D.), Drugs and Child Health, University of Florence, Italy
| | - Leslie W Jacobson
- From the Department of Neuroscience (G.S., S.F., A.E.), Università Cattolica del Sacro Cuore, Rome, Italy; German Center for Neurodegenerative Diseases (DZNE) Berlin (G.S.), Berlin, Germany; Nuffield Department of Clinical Neurosciences (A.V., B.S., L.W.J.), University of Oxford; Fluidic Analytics Ltd (S.D.), The Paddocks Business Centre, Cambridge, United Kingdom; and Department of Neurosciences (V.D.), Drugs and Child Health, University of Florence, Italy
| | - Sean Devenish
- From the Department of Neuroscience (G.S., S.F., A.E.), Università Cattolica del Sacro Cuore, Rome, Italy; German Center for Neurodegenerative Diseases (DZNE) Berlin (G.S.), Berlin, Germany; Nuffield Department of Clinical Neurosciences (A.V., B.S., L.W.J.), University of Oxford; Fluidic Analytics Ltd (S.D.), The Paddocks Business Centre, Cambridge, United Kingdom; and Department of Neurosciences (V.D.), Drugs and Child Health, University of Florence, Italy
| | - Amelia Evoli
- From the Department of Neuroscience (G.S., S.F., A.E.), Università Cattolica del Sacro Cuore, Rome, Italy; German Center for Neurodegenerative Diseases (DZNE) Berlin (G.S.), Berlin, Germany; Nuffield Department of Clinical Neurosciences (A.V., B.S., L.W.J.), University of Oxford; Fluidic Analytics Ltd (S.D.), The Paddocks Business Centre, Cambridge, United Kingdom; and Department of Neurosciences (V.D.), Drugs and Child Health, University of Florence, Italy
| | - Valentina Damato
- From the Department of Neuroscience (G.S., S.F., A.E.), Università Cattolica del Sacro Cuore, Rome, Italy; German Center for Neurodegenerative Diseases (DZNE) Berlin (G.S.), Berlin, Germany; Nuffield Department of Clinical Neurosciences (A.V., B.S., L.W.J.), University of Oxford; Fluidic Analytics Ltd (S.D.), The Paddocks Business Centre, Cambridge, United Kingdom; and Department of Neurosciences (V.D.), Drugs and Child Health, University of Florence, Italy
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He M, Zhou X, Wang X. Glycosylation: mechanisms, biological functions and clinical implications. Signal Transduct Target Ther 2024; 9:194. [PMID: 39098853 PMCID: PMC11298558 DOI: 10.1038/s41392-024-01886-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Revised: 05/25/2024] [Accepted: 06/07/2024] [Indexed: 08/06/2024] Open
Abstract
Protein post-translational modification (PTM) is a covalent process that occurs in proteins during or after translation through the addition or removal of one or more functional groups, and has a profound effect on protein function. Glycosylation is one of the most common PTMs, in which polysaccharides are transferred to specific amino acid residues in proteins by glycosyltransferases. A growing body of evidence suggests that glycosylation is essential for the unfolding of various functional activities in organisms, such as playing a key role in the regulation of protein function, cell adhesion and immune escape. Aberrant glycosylation is also closely associated with the development of various diseases. Abnormal glycosylation patterns are closely linked to the emergence of various health conditions, including cancer, inflammation, autoimmune disorders, and several other diseases. However, the underlying composition and structure of the glycosylated residues have not been determined. It is imperative to fully understand the internal structure and differential expression of glycosylation, and to incorporate advanced detection technologies to keep the knowledge advancing. Investigations on the clinical applications of glycosylation focused on sensitive and promising biomarkers, development of more effective small molecule targeted drugs and emerging vaccines. These studies provide a new area for novel therapeutic strategies based on glycosylation.
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Affiliation(s)
- Mengyuan He
- Department of Hematology, Shandong Provincial Hospital, Shandong University, Jinan, Shandong, 250021, China
| | - Xiangxiang Zhou
- Department of Hematology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China.
- National Clinical Research Center for Hematologic Diseases, the First Affiliated Hospital of Soochow University, Suzhou, 251006, China.
| | - Xin Wang
- Department of Hematology, Shandong Provincial Hospital, Shandong University, Jinan, Shandong, 250021, China.
- Department of Hematology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China.
- National Clinical Research Center for Hematologic Diseases, the First Affiliated Hospital of Soochow University, Suzhou, 251006, China.
- Taishan Scholars Program of Shandong Province, Jinan, Shandong, 250021, China.
- Branch of National Clinical Research Center for Hematologic Diseases, Jinan, Shandong, 250021, China.
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Cavalcante P, Mantegazza R, Antozzi C. Targeting autoimmune mechanisms by precision medicine in Myasthenia Gravis. Front Immunol 2024; 15:1404191. [PMID: 38903526 PMCID: PMC11187261 DOI: 10.3389/fimmu.2024.1404191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 05/24/2024] [Indexed: 06/22/2024] Open
Abstract
Myasthenia Gravis (MG) is a chronic disabling autoimmune disease caused by autoantibodies to the neuromuscular junction (NMJ), characterized clinically by fluctuating weakness and early fatigability of ocular, skeletal and bulbar muscles. Despite being commonly considered a prototypic autoimmune disorder, MG is a complex and heterogeneous condition, presenting with variable clinical phenotypes, likely due to distinct pathophysiological settings related with different immunoreactivities, symptoms' distribution, disease severity, age at onset, thymic histopathology and response to therapies. Current treatment of MG based on international consensus guidelines allows to effectively control symptoms, but most patients do not reach complete stable remission and require life-long immunosuppressive (IS) therapies. Moreover, a proportion of them is refractory to conventional IS treatment, highlighting the need for more specific and tailored strategies. Precision medicine is a new frontier of medicine that promises to greatly increase therapeutic success in several diseases, including autoimmune conditions. In MG, B cell activation, antibody recycling and NMJ damage by the complement system are crucial mechanisms, and their targeting by innovative biological drugs has been proven to be effective and safe in clinical trials. The switch from conventional IS to novel precision medicine approaches based on these drugs could prospectively and significantly improve MG care. In this review, we provide an overview of key immunopathogenetic processes underlying MG, and discuss on emerging biological drugs targeting them. We also discuss on future direction of research to address the need for patients' stratification in endotypes according with genetic and molecular biomarkers for successful clinical decision making within precision medicine workflow.
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Affiliation(s)
- Paola Cavalcante
- Neurology 4 – Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Renato Mantegazza
- Neurology 4 – Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Carlo Antozzi
- Neurology 4 – Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
- Immunotherapy and Apheresis Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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4
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Ünlü S, Sánchez Navarro BG, Cakan E, Berchtold D, Meleka Hanna R, Vural S, Vural A, Meisel A, Fichtner ML. Exploring the depths of IgG4: insights into autoimmunity and novel treatments. Front Immunol 2024; 15:1346671. [PMID: 38698867 PMCID: PMC11063302 DOI: 10.3389/fimmu.2024.1346671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 02/29/2024] [Indexed: 05/05/2024] Open
Abstract
IgG4 subclass antibodies represent the rarest subclass of IgG antibodies, comprising only 3-5% of antibodies circulating in the bloodstream. These antibodies possess unique structural features, notably their ability to undergo a process known as fragment-antigen binding (Fab)-arm exchange, wherein they exchange half-molecules with other IgG4 antibodies. Functionally, IgG4 antibodies primarily block and exert immunomodulatory effects, particularly in the context of IgE isotype-mediated hypersensitivity reactions. In the context of disease, IgG4 antibodies are prominently observed in various autoimmune diseases combined under the term IgG4 autoimmune diseases (IgG4-AID). These diseases include myasthenia gravis (MG) with autoantibodies against muscle-specific tyrosine kinase (MuSK), nodo-paranodopathies with autoantibodies against paranodal and nodal proteins, pemphigus vulgaris and foliaceus with antibodies against desmoglein and encephalitis with antibodies against LGI1/CASPR2. Additionally, IgG4 antibodies are a prominent feature in the rare entity of IgG4 related disease (IgG4-RD). Intriguingly, both IgG4-AID and IgG4-RD demonstrate a remarkable responsiveness to anti-CD20-mediated B cell depletion therapy (BCDT), suggesting shared underlying immunopathologies. This review aims to provide a comprehensive exploration of B cells, antibody subclasses, and their general properties before examining the distinctive characteristics of IgG4 subclass antibodies in the context of health, IgG4-AID and IgG4-RD. Furthermore, we will examine potential therapeutic strategies for these conditions, with a special focus on leveraging insights gained from anti-CD20-mediated BCDT. Through this analysis, we aim to enhance our understanding of the pathogenesis of IgG4-mediated diseases and identify promising possibilities for targeted therapeutic intervention.
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Affiliation(s)
- Selen Ünlü
- Koç University Research Center for Translational Medicine (KUTTAM), İstanbul, Türkiye
- Koç University School of Medicine, Istanbul, Türkiye
| | - Blanca G. Sánchez Navarro
- Department of Neurology with Experimental Neurology, Integrated Myasthenia Gravis Center, Neuroscience Clinical Research Center, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Elif Cakan
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Cambridge, MA, United States
| | - Daniel Berchtold
- Department of Neurology with Experimental Neurology, Integrated Myasthenia Gravis Center, Neuroscience Clinical Research Center, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Rafael Meleka Hanna
- Department of Neurology with Experimental Neurology, Integrated Myasthenia Gravis Center, Neuroscience Clinical Research Center, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Secil Vural
- Koç University Research Center for Translational Medicine (KUTTAM), İstanbul, Türkiye
- Department of Dermatology and Venereology, Koç University School of Medicine, İstanbul, Türkiye
| | - Atay Vural
- Koç University Research Center for Translational Medicine (KUTTAM), İstanbul, Türkiye
- Department of Neurology, Koç University School of Medicine, İstanbul, Türkiye
| | - Andreas Meisel
- Department of Neurology with Experimental Neurology, Integrated Myasthenia Gravis Center, Neuroscience Clinical Research Center, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Miriam L. Fichtner
- Koç University Research Center for Translational Medicine (KUTTAM), İstanbul, Türkiye
- Department of Neurology with Experimental Neurology, Integrated Myasthenia Gravis Center, Neuroscience Clinical Research Center, Charité Universitätsmedizin Berlin, Berlin, Germany
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5
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Jaime D, Fish LA, Madigan LA, Xi C, Piccoli G, Ewing MD, Blaauw B, Fallon JR. The MuSK-BMP pathway maintains myofiber size in slow muscle through regulation of Akt-mTOR signaling. Skelet Muscle 2024; 14:1. [PMID: 38172960 PMCID: PMC10763067 DOI: 10.1186/s13395-023-00329-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 10/19/2023] [Indexed: 01/05/2024] Open
Abstract
Myofiber size regulation is critical in health, disease, and aging. MuSK (muscle-specific kinase) is a BMP (bone morphogenetic protein) co-receptor that promotes and shapes BMP signaling. MuSK is expressed at all neuromuscular junctions and is also present extrasynaptically in the mouse soleus, whose predominantly oxidative fiber composition is akin to that of human muscle. To investigate the role of the MuSK-BMP pathway in vivo, we generated mice lacking the BMP-binding MuSK Ig3 domain. These ∆Ig3-MuSK mice are viable and fertile with innervation levels comparable to wild type. In 3-month-old mice, myofibers are smaller in the slow soleus, but not in the fast tibialis anterior (TA). Transcriptomic analysis revealed soleus-selective decreases in RNA metabolism and protein synthesis pathways as well as dysregulation of IGF1-Akt-mTOR pathway components. Biochemical analysis showed that Akt-mTOR signaling is reduced in soleus but not TA. We propose that the MuSK-BMP pathway acts extrasynaptically to maintain myofiber size in slow muscle by promoting protein synthetic pathways including IGF1-Akt-mTOR signaling. These results reveal a novel mechanism for regulating myofiber size in slow muscle and introduce the MuSK-BMP pathway as a target for promoting muscle growth and combatting atrophy.
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Grants
- R41 AG073144 NIA NIH HHS
- T32 MH020068 NIMH NIH HHS
- U01 NS064295, R41 AG073144, R21 NS112743, R21 AG073743, P30 GM103410, P30 RR031153, P20 RR018728, S10 RR02763, R25GM083270, 2T32AG041688, and T32 MH20068 NIH HHS
- P30 GM103410 NIGMS NIH HHS
- T32 AG041688 NIA NIH HHS
- P30 RR031153 NCRR NIH HHS
- U01 NS064295 NINDS NIH HHS
- R21 NS112743 NINDS NIH HHS
- P20 RR018728 NCRR NIH HHS
- R21 AG073743 NIA NIH HHS
- R25 GM083270 NIGMS NIH HHS
- National Institutes of Health
- Carney Institute for Brain Sciences
- ALS Finding a Cure
- AFM-Téléthon
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Affiliation(s)
- Diego Jaime
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
| | - Lauren A Fish
- Department of Neuroscience, Brown University, Providence, RI, 02912, USA
| | - Laura A Madigan
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
| | - Chengjie Xi
- Department of Neuroscience, Brown University, Providence, RI, 02912, USA
| | - Giorgia Piccoli
- Veneto Institute of Molecular Medicine (VIMM), Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Madison D Ewing
- Department of Neuroscience, Brown University, Providence, RI, 02912, USA
| | - Bert Blaauw
- Veneto Institute of Molecular Medicine (VIMM), Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Justin R Fallon
- Department of Neuroscience, Brown University, Providence, RI, 02912, USA.
- Carney Institute for Neuroscience, Brown University, Providence, RI, USA.
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Aoun M, Coelho A, Krämer A, Saxena A, Sabatier P, Beusch CM, Lönnblom E, Geng M, Do NN, Xu Z, Zhang J, He Y, Romero Castillo L, Abolhassani H, Xu B, Viljanen J, Rorbach J, Fernandez Lahore G, Gjertsson I, Kastbom A, Sjöwall C, Kihlberg J, Zubarev RA, Burkhardt H, Holmdahl R. Antigen-presenting autoreactive B cells activate regulatory T cells and suppress autoimmune arthritis in mice. J Exp Med 2023; 220:e20230101. [PMID: 37695523 PMCID: PMC10494526 DOI: 10.1084/jem.20230101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 05/31/2023] [Accepted: 08/16/2023] [Indexed: 09/12/2023] Open
Abstract
B cells undergo several rounds of selection to eliminate potentially pathogenic autoreactive clones, but in contrast to T cells, evidence of positive selection of autoreactive B cells remains moot. Using unique tetramers, we traced natural autoreactive B cells (C1-B) specific for a defined triple-helical epitope on collagen type-II (COL2), constituting a sizeable fraction of the physiological B cell repertoire in mice, rats, and humans. Adoptive transfer of C1-B suppressed arthritis independently of IL10, separating them from IL10-secreting regulatory B cells. Single-cell sequencing revealed an antigen processing and presentation signature, including induced expression of CD72 and CCR7 as surface markers. C1-B presented COL2 to T cells and induced the expansion of regulatory T cells in a contact-dependent manner. CD72 blockade impeded this effect suggesting a new downstream suppressor mechanism that regulates antigen-specific T cell tolerization. Thus, our results indicate that autoreactive antigen-specific naïve B cells tolerize infiltrating T cells against self-antigens to impede the development of tissue-specific autoimmune inflammation.
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Affiliation(s)
- Mike Aoun
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Ana Coelho
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Alexander Krämer
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Amit Saxena
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Pierre Sabatier
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Christian Michel Beusch
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Erik Lönnblom
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Manman Geng
- Precision Medicine Institute, The Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Nhu-Nguyen Do
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
- Fraunhofer Institute for Translational Medicine and Pharmacology, and Fraunhofer Cluster of Excellence for Immune-Mediated Diseases, Frankfurt am Main, Germany
| | - Zhongwei Xu
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Jingdian Zhang
- Max Planck Institute Biology of Ageing—Karolinska Institute Laboratory, Karolinska Institute, Solna, Sweden
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Yibo He
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Laura Romero Castillo
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Hassan Abolhassani
- Division of Clinical Immunology, Department of Biosciences and Nutrition, Karolinska Institutet, Karolinska University Hospital, Neo Building, Solna, Sweden
| | - Bingze Xu
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Johan Viljanen
- Department of Chemistry, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Joanna Rorbach
- Max Planck Institute Biology of Ageing—Karolinska Institute Laboratory, Karolinska Institute, Solna, Sweden
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Gonzalo Fernandez Lahore
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
| | - Inger Gjertsson
- Department of Rheumatology and Inflammation Research, University of Gothenburg, Gothenburg, Sweden
| | - Alf Kastbom
- Division of Inflammation and Infection, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Christopher Sjöwall
- Division of Inflammation and Infection, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Jan Kihlberg
- Department of Chemistry, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Roman A. Zubarev
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
- Department of Pharmacological and Technological Chemistry, I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Harald Burkhardt
- Fraunhofer Institute for Translational Medicine and Pharmacology, and Fraunhofer Cluster of Excellence for Immune-Mediated Diseases, Frankfurt am Main, Germany
- Division of Rheumatology, University Hospital Frankfurt, Goethe University, Frankfurt am Main, Germany
| | - Rikard Holmdahl
- Division of Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Solna, Sweden
- Precision Medicine Institute, The Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
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7
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Vakrakou AG, Karachaliou E, Chroni E, Zouvelou V, Tzanetakos D, Salakou S, Papadopoulou M, Tzartos S, Voumvourakis K, Kilidireas C, Giannopoulos S, Tsivgoulis G, Tzartos J. Immunotherapies in MuSK-positive Myasthenia Gravis; an IgG4 antibody-mediated disease. Front Immunol 2023; 14:1212757. [PMID: 37564637 PMCID: PMC10410455 DOI: 10.3389/fimmu.2023.1212757] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 07/05/2023] [Indexed: 08/12/2023] Open
Abstract
Muscle-specific kinase (MuSK) Myasthenia Gravis (MG) represents a prototypical antibody-mediated disease characterized by predominantly focal muscle weakness (neck, facial, and bulbar muscles) and fatigability. The pathogenic antibodies mostly belong to the immunoglobulin subclass (Ig)G4, a feature which attributes them their specific properties and pathogenic profile. On the other hand, acetylcholine receptor (AChR) MG, the most prevalent form of MG, is characterized by immunoglobulin (Ig)G1 and IgG3 antibodies to the AChR. IgG4 class autoantibodies are impotent to fix complement and only weakly bind Fc-receptors expressed on immune cells and exert their pathogenicity via interfering with the interaction between their targets and binding partners (e.g. between MuSK and LRP4). Cardinal differences between AChR and MuSK-MG are the thymus involvement (not prominent in MuSK-MG), the distinct HLA alleles, and core immunopathological patterns of pathology in neuromuscular junction, structure, and function. In MuSK-MG, classical treatment options are usually less effective (e.g. IVIG) with the need for prolonged and high doses of steroids difficult to be tapered to control symptoms. Exceptional clinical response to plasmapheresis and rituximab has been particularly observed in these patients. Reduction of antibody titers follows the clinical efficacy of anti-CD20 therapies, a feature implying the role of short-lived plasma cells (SLPB) in autoantibody production. Novel therapeutic monoclonal against B cells at different stages of their maturation (like plasmablasts), or against molecules involved in B cell activation, represent promising therapeutic targets. A revolution in autoantibody-mediated diseases is pharmacological interference with the neonatal Fc receptor, leading to a rapid reduction of circulating IgGs (including autoantibodies), an approach already suitable for AChR-MG and promising for MuSK-MG. New precision medicine approaches involve Chimeric autoantibody receptor T (CAAR-T) cells that are engineered to target antigen-specific B cells in MuSK-MG and represent a milestone in the development of targeted immunotherapies. This review aims to provide a detailed update on the pathomechanisms involved in MuSK-MG (cellular and humoral aberrations), fostering the understanding of the latest indications regarding the efficacy of different treatment strategies.
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Affiliation(s)
- Aigli G. Vakrakou
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Eleni Karachaliou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Elisabeth Chroni
- Department of Neurology, School of Medicine, University of Patras, Patras, Greece
| | - Vasiliki Zouvelou
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Dimitrios Tzanetakos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Stavroula Salakou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Marianna Papadopoulou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
- Department of Physiotherapy, University of West Attica, Athens, Greece
| | - Socrates Tzartos
- Tzartos NeuroDiagnostics, Athens, Greece
- Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
- Department of Pharmacy, University of Patras, Patras, Greece
| | - Konstantinos Voumvourakis
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Constantinos Kilidireas
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
- Department of Neurology, Henry Dunant Hospital Center, Athens, Greece
| | - Sotirios Giannopoulos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Georgios Tsivgoulis
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
- Department of Neurology, The University of Tennessee Health Science Center, Memphis, TN, United States
| | - John Tzartos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
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Mori S, Suzuki S, Konishi T, Kawaguchi N, Kishi M, Kuwabara S, Ishizuchi K, Zhou H, Shibasaki F, Tsumoto H, Omura T, Miura Y, Mori S, Higashihara M, Murayama S, Shigemoto K. Proteolytic ectodomain shedding of muscle-specific tyrosine kinase in myasthenia gravis. Exp Neurol 2023; 361:114300. [PMID: 36525997 DOI: 10.1016/j.expneurol.2022.114300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 11/07/2022] [Accepted: 12/10/2022] [Indexed: 12/15/2022]
Abstract
Autoantibodies to muscle-specific tyrosine kinase (MuSK) proteins at the neuromuscular junction (NMJ) cause refractory generalized myasthenia gravis (MG) with dyspnea more frequently than other MG subtypes. However, the mechanisms via which MuSK, a membrane protein locally expressed on the NMJ of skeletal muscle, is supplied to the immune system as an autoantigen remains unknown. Here, we identified MuSK in both mouse and human serum, with the amount of MuSK dramatically increasing in mice with motor nerve denervation and in MG model mice. Peptide analysis by liquid chromatography-tandem-mass spectrometry (LC-MS/MS) confirmed the presence of MuSK in both human and mouse serum. Furthermore, some patients with MG have significantly higher amounts of MuSK in serum than healthy controls. Our results indicated that the secretion of MuSK proteins from muscles into the bloodstream was induced by ectodomain shedding triggered by neuromuscular junction failure. The results may explain why MuSK-MG is refractory to treatments and causes rapid muscle atrophy in some patients due to the denervation associated with Ab-induced disruption of neuromuscular transmission at the NMJ. Such discoveries pave the way for new MG treatments, and MuSK may be used as a biomarker for other neuromuscular diseases in preclinical studies, clinical diagnostics, therapeutics, and drug discovery.
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Affiliation(s)
- Shuuichi Mori
- Research Team for Geriatric Medicine, Tokyo Metropolitan Institute of Gerontology (TMIG), Tokyo, Japan
| | - Shigeaki Suzuki
- Department of Neurology, Keio University School of Medicine, Tokyo, Japan
| | | | - Naoki Kawaguchi
- Dowa Institute of Clinical Neuroscience, Neurology Clinic Chiba, Chiba, Japan
| | - Masahiko Kishi
- Department of Internal Medicine, Toho University Sakura Medical Center, Chiba, Japan
| | - Satoshi Kuwabara
- Department of Neurology, Chiba University School of Medicine, Chiba, Japan
| | - Kei Ishizuchi
- Department of Neurology, Keio University School of Medicine, Tokyo, Japan
| | - Heying Zhou
- Research Team for Geriatric Medicine, Tokyo Metropolitan Institute of Gerontology (TMIG), Tokyo, Japan
| | - Futoshi Shibasaki
- Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Hiroki Tsumoto
- Research Team for Mechanism of Aging, TMIG, Tokyo, Japan
| | - Takuya Omura
- Research Team for Geriatric Medicine, Tokyo Metropolitan Institute of Gerontology (TMIG), Tokyo, Japan
| | - Yuri Miura
- Research Team for Mechanism of Aging, TMIG, Tokyo, Japan
| | - Seijiro Mori
- Research Team for Geriatric Medicine, Tokyo Metropolitan Institute of Gerontology (TMIG), Tokyo, Japan
| | - Mana Higashihara
- Department of Neurology, Tokyo Metropolitan Geriatric Hospital, Tokyo (TMGHIG), Japan
| | | | - Kazuhiro Shigemoto
- Research Team for Geriatric Medicine, Tokyo Metropolitan Institute of Gerontology (TMIG), Tokyo, Japan.
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Jaime D, Fish LA, Madigan LA, Ewing MD, Fallon JR. The MuSK-BMP pathway maintains myofiber size in slow muscle through regulation of Akt- mTOR signaling. RESEARCH SQUARE 2023:rs.3.rs-2613527. [PMID: 36909467 PMCID: PMC10002845 DOI: 10.21203/rs.3.rs-2613527/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Myofiber size regulation is critical in health, disease, and aging. MuSK (muscle-specific kinase) is a BMP (bone morphogenetic protein) co-receptor that promotes and shapes BMP signaling. MuSK is expressed at all neuromuscular junctions and is also present extrasynaptically in the slow soleus muscle. To investigate the role of the MuSK-BMP pathway in vivo we generated mice lacking the BMP-binding MuSK Ig3 domain. These ΔIg3-MuSKmice are viable and fertile with innervation levels comparable to wild type. In 3-month-old mice myofibers are smaller in the slow soleus, but not in the fast tibialis anterior (TA). Transcriptomic analysis revealed soleus-selective decreases in RNA metabolism and protein synthesis pathways as well as dysregulation of IGF1-Akt-mTOR pathway components. Biochemical analysis showed that Akt-mTOR signaling is reduced in soleus but not TA. We propose that the MuSK-BMP pathway acts extrasynaptically to maintain myofiber size in slow muscle by promoting protein synthetic pathways including IGF1-Akt-mTOR signaling. These results reveal a novel mechanism for regulating myofiber size in slow muscle and introduce the MuSK-BMP pathway as a target for promoting muscle growth and combatting atrophy.
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10
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Differences in IgG autoantibody Fab glycosylation across autoimmune diseases. J Allergy Clin Immunol 2023:S0091-6749(23)00091-X. [PMID: 36716825 DOI: 10.1016/j.jaci.2022.10.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 10/12/2022] [Accepted: 10/14/2022] [Indexed: 01/29/2023]
Abstract
BACKGROUND Increased prevalence of autoantibody Fab glycosylation has been demonstrated for several autoimmune diseases. OBJECTIVES To study whether elevated Fab glycosylation is a common feature of autoimmunity, this study investigated Fab glycosylation levels on serum IgG and its subclasses for autoantibodies associated with a range of different B cell-mediated autoimmune diseases, including rheumatoid arthritis, myasthenia gravis subtypes, pemphigus vulgaris, antineutrophil cytoplasmic antibody-associated vasculitis, systemic lupus erythematosus, anti-glomerular basement membrane glomerulonephritis, thrombotic thrombocytopenic purpura, and Guillain-Barré syndrome. METHODS The level of Fab glycosylated IgG antibodies was assessed by lectin affinity chromatography and autoantigen-specific immunoassays. RESULTS In 6 of 10 autoantibody responses, in 5 of 8 diseases, the investigators found increased levels of Fab glycosylation on IgG autoantibodies that varied from 86% in rheumatoid arthritis to 26% in systemic lupus erythematosus. Elevated autoantibody Fab glycosylation was not restricted to IgG4, which is known to be prone to Fab glycosylation, but was also present in IgG1. When autoimmune diseases with a chronic disease course were compared with more acute autoimmune illnesses, increased Fab glycosylation was restricted to the chronic diseases. As a proxy for chronic autoantigen exposure, the investigators determined Fab glycosylation levels on antibodies to common latent herpes viruses, as well as to glycoprotein 120 in individuals who are chronically HIV-1-infected. Immunity to these viral antigens was not associated with increased Fab glycosylation levels, indicating that chronic antigen-stimulation as such does not lead to increased Fab glycosylation levels. CONCLUSIONS These data indicate that in chronic but not acute B cell-mediated autoimmune diseases, disease-specific autoantibodies are enriched for Fab glycans.
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11
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Fichtner ML, Hoehn KB, Ford EE, Mane-Damas M, Oh S, Waters P, Payne AS, Smith ML, Watson CT, Losen M, Martinez-Martinez P, Nowak RJ, Kleinstein SH, O'Connor KC. Reemergence of pathogenic, autoantibody-producing B cell clones in myasthenia gravis following B cell depletion therapy. Acta Neuropathol Commun 2022; 10:154. [PMID: 36307868 PMCID: PMC9617453 DOI: 10.1186/s40478-022-01454-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 09/30/2022] [Indexed: 11/12/2022] Open
Abstract
Myasthenia gravis (MG) is an autoantibody-mediated autoimmune disorder of the neuromuscular junction. A small subset of patients (<10%) with MG, have autoantibodies targeting muscle-specific tyrosine kinase (MuSK). MuSK MG patients respond well to CD20-mediated B cell depletion therapy (BCDT); most achieve complete stable remission. However, relapse often occurs. To further understand the immunomechanisms underlying relapse, we studied autoantibody-producing B cells over the course of BCDT. We developed a fluorescently labeled antigen to enrich for MuSK-specific B cells, which was validated with a novel Nalm6 cell line engineered to express a human MuSK-specific B cell receptor. B cells (≅ 2.6 million) from 12 different samples collected from nine MuSK MG patients were screened for MuSK specificity. We successfully isolated two MuSK-specific IgG4 subclass-expressing plasmablasts from two of these patients, who were experiencing a relapse after a BCDT-induced remission. Human recombinant MuSK mAbs were then generated to validate binding specificity and characterize their molecular properties. Both mAbs were strong MuSK binders, they recognized the Ig1-like domain of MuSK, and showed pathogenic capacity when tested in an acetylcholine receptor (AChR) clustering assay. The presence of persistent clonal relatives of these MuSK-specific B cell clones was investigated through B cell receptor repertoire tracing of 63,977 unique clones derived from longitudinal samples collected from these two patients. Clonal variants were detected at multiple timepoints spanning more than five years and reemerged after BCDT-mediated remission, predating disease relapse by several months. These findings demonstrate that a reservoir of rare pathogenic MuSK autoantibody-expressing B cell clones survive BCDT and reemerge into circulation prior to manifestation of clinical relapse. Overall, this study provides both a mechanistic understanding of MuSK MG relapse and a valuable candidate biomarker for relapse prediction.
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Affiliation(s)
- Miriam L Fichtner
- Department of Neurology, Yale University School of Medicine, 300 George Street - Room 353J, New Haven, CT, 06511, USA
- Department of Immunobiology, Yale University School of Medicine, 300 George Street - Room 353J, New Haven, CT, 06511, USA
| | - Kenneth B Hoehn
- Department of Pathology, Yale School of Medicine, New Haven, CT, USA
| | - Easton E Ford
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Marina Mane-Damas
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Sangwook Oh
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Patrick Waters
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Aimee S Payne
- Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Melissa L Smith
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY, USA
| | - Corey T Watson
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY, USA
| | - Mario Losen
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Pilar Martinez-Martinez
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Richard J Nowak
- Department of Neurology, Yale University School of Medicine, 300 George Street - Room 353J, New Haven, CT, 06511, USA
| | - Steven H Kleinstein
- Department of Immunobiology, Yale University School of Medicine, 300 George Street - Room 353J, New Haven, CT, 06511, USA
- Department of Pathology, Yale School of Medicine, New Haven, CT, USA
- Program in Computational Biology & Bioinformatics, Yale University, New Haven, CT, USA
| | - Kevin C O'Connor
- Department of Neurology, Yale University School of Medicine, 300 George Street - Room 353J, New Haven, CT, 06511, USA.
- Department of Immunobiology, Yale University School of Medicine, 300 George Street - Room 353J, New Haven, CT, 06511, USA.
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Abstract
PURPOSE OF REVIEW This review summarizes recent insights into the immunopathogenesis of autoimmune myasthenia gravis (MG). Mechanistic understanding is presented according to MG disease subtypes and by leveraging the knowledge gained through the use of immunomodulating biological therapeutics. RECENT FINDINGS The past two years of research on MG have led to a more accurate definition of the mechanisms through which muscle-specific tyrosine kinase (MuSK) autoantibodies induce pathology. Novel insights have also emerged from the collection of stronger evidence on the pathogenic capacity of low-density lipoprotein receptor-related protein 4 autoantibodies. Clinical observations have revealed a new MG phenotype triggered by cancer immunotherapy, but the underlying immunobiology remains undetermined. From a therapeutic perspective, MG patients can now benefit from a wider spectrum of treatment options. Such therapies have uncovered profound differences in clinical responses between and within the acetylcholine receptor and MuSK MG subtypes. Diverse mechanisms of immunopathology between the two subtypes, as well as qualitative nuances in the autoantibody repertoire of each patient, likely underpin the variability in therapeutic outcomes. Although predictive biomarkers of clinical response are lacking, these observations have ignited the development of assays that might assist clinicians in the choice of specific therapeutic strategies. SUMMARY Recent advances in the understanding of autoantibody functionalities are bringing neuroimmunologists closer to a more detailed appreciation of the mechanisms that govern MG pathology. Future investigations on the immunological heterogeneity among MG patients will be key to developing effective, individually tailored therapies.
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Affiliation(s)
- Gianvito Masi
- Department of Neurology, Yale School of Medicine, New Haven, CT 06511 USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT 06511 USA
| | - Kevin C. O’Connor
- Department of Neurology, Yale School of Medicine, New Haven, CT 06511 USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT 06511 USA
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13
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Jentzer A, Attal A, Roué C, Raymond J, Lleixà C, Illa I, Querol L, Taieb G, Devaux J. IgG4 Valency Modulates the Pathogenicity of Anti–Neurofascin-155 IgG4 in Autoimmune Nodopathy. NEUROLOGY - NEUROIMMUNOLOGY NEUROINFLAMMATION 2022; 9:9/5/e200014. [PMID: 35948442 PMCID: PMC9365386 DOI: 10.1212/nxi.0000000000200014] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/18/2022] [Indexed: 12/03/2022]
Abstract
Background and Objectives IgG4 autoantibodies to neurofascin-155 (Nfasc155) are associated with a subgroup of patients with chronic inflammatory demyelinating polyneuropathy (CIDP), currently named autoimmune nodopathy. We previously demonstrated that those antibodies alter conduction along myelinated axons by inducing Nfasc155 depletion and paranode destruction. In blood, IgG4 have the potency to exchange their moiety with other unrelated IgG4 through a process called Fab-arm exchange (FAE). This process results in functionally monovalent antibodies and may affect the pathogenicity of autoantibodies. Here, we examined this issue and whether FAE is beneficial or detrimental for Nfasc155 autoimmune nodopathy. Methods The bivalency and monospecificity of anti-Nfasc155 were examined by sandwich ELISA in 10 reactive patients, 10 unreactive CIDP patients, and 10 healthy controls. FAE was induced in vitro using reduced glutathione and unreactive IgG4, and the ratio of the κ:λ light chain was monitored. To determine the pathogenic potential of bivalent anti-Nfasc155 IgG4, autoantibodies derived from patients were enzymatically cleaved into monovalent Fab and bivalent F(ab’)2 or swapped with unreactive IgG4 and then were injected in neonatal animals. Results Monospecific bivalent IgG4 against Nfasc155 were detected in the serum of all reactive patients, indicating that a fraction of IgG4 have not undergone FAE in situ. These IgG4 were, nonetheless, capable of engaging into FAE with unreactive IgG4 in vitro, and this decreased the levels of monospecific antibodies and modulated the ratio of the κ:λ light chain. When injected in animals, monovalent anti-Nfasc155 Fab did not alter the formation of paranodes; by contrast, both native anti-Nfasc155 IgG4 and F(ab’)2 fragments strongly impaired paranode formation. The promotion of FAE with unreactive IgG4 also strongly diminished the pathogenic potential of anti-Nfasc155 IgG4 in animals and decreased IgG4 clustering on Schwann cells. Discussion Our findings demonstrate that monospecific and bivalent anti-Nfasc155 IgG4 are detected in patients and that those autoantibodies are the pathogenic ones. The transformation of anti-Nfasc155 IgG4 into monovalent Fab or functionally monovalent IgG4 through FAE strongly decreases paranodal alterations. Bivalency thus appears crucial for Nfasc155 clustering and paranode destruction.
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Affiliation(s)
- Alexandre Jentzer
- From the Institute for Neurosciences of Montpellier (A.J., A.A., G.T., J.D.), INSERM U1051, Montpellier University, Hôpital Saint Eloi, France; Department of Immunology (A.J.), CHU Montpellier, France ; Department of Neurology (A.A., G.T.), CHU Montpellier, Hôpital Gui de Chauliac, France; Institut de Génomique Fonctionnelle (C.R., J.R., G.T., J.D.), CNRS UMR5203, France; and Neuromuscular Diseases Unit (C.L., I.I., L.Q.), Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Spain
| | - Arthur Attal
- From the Institute for Neurosciences of Montpellier (A.J., A.A., G.T., J.D.), INSERM U1051, Montpellier University, Hôpital Saint Eloi, France; Department of Immunology (A.J.), CHU Montpellier, France ; Department of Neurology (A.A., G.T.), CHU Montpellier, Hôpital Gui de Chauliac, France; Institut de Génomique Fonctionnelle (C.R., J.R., G.T., J.D.), CNRS UMR5203, France; and Neuromuscular Diseases Unit (C.L., I.I., L.Q.), Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Spain
| | - Clémence Roué
- From the Institute for Neurosciences of Montpellier (A.J., A.A., G.T., J.D.), INSERM U1051, Montpellier University, Hôpital Saint Eloi, France; Department of Immunology (A.J.), CHU Montpellier, France ; Department of Neurology (A.A., G.T.), CHU Montpellier, Hôpital Gui de Chauliac, France; Institut de Génomique Fonctionnelle (C.R., J.R., G.T., J.D.), CNRS UMR5203, France; and Neuromuscular Diseases Unit (C.L., I.I., L.Q.), Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Spain
| | - Julie Raymond
- From the Institute for Neurosciences of Montpellier (A.J., A.A., G.T., J.D.), INSERM U1051, Montpellier University, Hôpital Saint Eloi, France; Department of Immunology (A.J.), CHU Montpellier, France ; Department of Neurology (A.A., G.T.), CHU Montpellier, Hôpital Gui de Chauliac, France; Institut de Génomique Fonctionnelle (C.R., J.R., G.T., J.D.), CNRS UMR5203, France; and Neuromuscular Diseases Unit (C.L., I.I., L.Q.), Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Spain
| | - Cinta Lleixà
- From the Institute for Neurosciences of Montpellier (A.J., A.A., G.T., J.D.), INSERM U1051, Montpellier University, Hôpital Saint Eloi, France; Department of Immunology (A.J.), CHU Montpellier, France ; Department of Neurology (A.A., G.T.), CHU Montpellier, Hôpital Gui de Chauliac, France; Institut de Génomique Fonctionnelle (C.R., J.R., G.T., J.D.), CNRS UMR5203, France; and Neuromuscular Diseases Unit (C.L., I.I., L.Q.), Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Spain
| | - Isabel Illa
- From the Institute for Neurosciences of Montpellier (A.J., A.A., G.T., J.D.), INSERM U1051, Montpellier University, Hôpital Saint Eloi, France; Department of Immunology (A.J.), CHU Montpellier, France ; Department of Neurology (A.A., G.T.), CHU Montpellier, Hôpital Gui de Chauliac, France; Institut de Génomique Fonctionnelle (C.R., J.R., G.T., J.D.), CNRS UMR5203, France; and Neuromuscular Diseases Unit (C.L., I.I., L.Q.), Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Spain
| | - Luis Querol
- From the Institute for Neurosciences of Montpellier (A.J., A.A., G.T., J.D.), INSERM U1051, Montpellier University, Hôpital Saint Eloi, France; Department of Immunology (A.J.), CHU Montpellier, France ; Department of Neurology (A.A., G.T.), CHU Montpellier, Hôpital Gui de Chauliac, France; Institut de Génomique Fonctionnelle (C.R., J.R., G.T., J.D.), CNRS UMR5203, France; and Neuromuscular Diseases Unit (C.L., I.I., L.Q.), Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Spain
| | - Guillaume Taieb
- From the Institute for Neurosciences of Montpellier (A.J., A.A., G.T., J.D.), INSERM U1051, Montpellier University, Hôpital Saint Eloi, France; Department of Immunology (A.J.), CHU Montpellier, France ; Department of Neurology (A.A., G.T.), CHU Montpellier, Hôpital Gui de Chauliac, France; Institut de Génomique Fonctionnelle (C.R., J.R., G.T., J.D.), CNRS UMR5203, France; and Neuromuscular Diseases Unit (C.L., I.I., L.Q.), Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Spain
| | - Jérôme Devaux
- From the Institute for Neurosciences of Montpellier (A.J., A.A., G.T., J.D.), INSERM U1051, Montpellier University, Hôpital Saint Eloi, France; Department of Immunology (A.J.), CHU Montpellier, France ; Department of Neurology (A.A., G.T.), CHU Montpellier, Hôpital Gui de Chauliac, France; Institut de Génomique Fonctionnelle (C.R., J.R., G.T., J.D.), CNRS UMR5203, France; and Neuromuscular Diseases Unit (C.L., I.I., L.Q.), Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Spain.
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14
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Descatoire M, Fritzen R, Rotman S, Kuntzelman G, Leber XC, Droz-Georget S, Thrasher AJ, Traggiai E, Candotti F. Critical role of WASp in germinal center tolerance through regulation of B cell apoptosis and diversification. Cell Rep 2022; 38:110474. [PMID: 35263577 DOI: 10.1016/j.celrep.2022.110474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/18/2021] [Accepted: 02/10/2022] [Indexed: 11/30/2022] Open
Abstract
A main feature of Wiskott-Aldrich syndrome (WAS) is increased susceptibility to autoimmunity. A key contribution of B cells to development of these complications has been demonstrated through studies of samples from affected individuals and mouse models of the disease, but the role of the WAS protein (WASp) in controlling peripheral tolerance has not been specifically explored. Here we show that B cell responses remain T cell dependent in constitutive WASp-deficient mice, whereas selective WASp deletion in germinal center B cells (GCBs) is sufficient to induce broad development of self-reactive antibodies and kidney pathology, pointing to loss of germinal center tolerance as a primary cause leading to autoimmunity. Mechanistically, we show that WASp is upregulated in GCBs and regulates apoptosis and plasma cell differentiation in the germinal center and that the somatic hypermutation-derived diversification is the basis of autoantibody development.
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Affiliation(s)
- Marc Descatoire
- Laboratory of Inherited Immune Disorders, Division of Immunology and Allergy, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland.
| | | | - Samuel Rotman
- Service of Clinical Pathology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | | | | | - Stephanie Droz-Georget
- Laboratory of Inherited Immune Disorders, Division of Immunology and Allergy, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Adrian J Thrasher
- University College of London, Great Ormond Street Institute of Child Health, London, UK
| | | | - Fabio Candotti
- Laboratory of Inherited Immune Disorders, Division of Immunology and Allergy, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
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15
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Huijbers MG, Marx A, Plomp JJ, Le Panse R, Phillips WD. Advances in the understanding of disease mechanisms of autoimmune neuromuscular junction disorders. Lancet Neurol 2022; 21:163-175. [DOI: 10.1016/s1474-4422(21)00357-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 09/15/2021] [Accepted: 10/06/2021] [Indexed: 01/19/2023]
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16
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Mandel-Brehm C, Fichtner ML, Jiang R, Winton VJ, Vazquez SE, Pham MC, Hoehn KB, Kelleher NL, Nowak RJ, Kleinstein SH, Wilson MR, DeRisi JL, O'Connor KC. Elevated N-Linked Glycosylation of IgG V Regions in Myasthenia Gravis Disease Subtypes. THE JOURNAL OF IMMUNOLOGY 2021; 207:2005-2014. [PMID: 34544801 DOI: 10.4049/jimmunol.2100225] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 08/10/2021] [Indexed: 02/06/2023]
Abstract
Elevated N-linked glycosylation of IgG V regions (IgG-VN-Glyc) is an emerging molecular phenotype associated with autoimmune disorders. To test the broader specificity of elevated IgG-VN-Glyc, we studied patients with distinct subtypes of myasthenia gravis (MG), a B cell-mediated autoimmune disease. Our experimental design focused on examining the B cell repertoire and total IgG. It specifically included adaptive immune receptor repertoire sequencing to quantify and characterize N-linked glycosylation sites in the circulating BCR repertoire, proteomics to examine glycosylation patterns of the total circulating IgG, and an exploration of human-derived recombinant autoantibodies, which were studied with mass spectrometry and Ag binding assays to respectively confirm occupation of glycosylation sites and determine whether they alter binding. We found that the frequency of IgG-VN-Glyc motifs was increased in the total BCR repertoire of patients with MG when compared with healthy donors. The elevated frequency was attributed to both biased V gene segment usage and somatic hypermutation. IgG-VN-Glyc could be observed in the total circulating IgG in a subset of patients with MG. Autoantigen binding, by four patient-derived MG autoantigen-specific mAbs with experimentally confirmed presence of IgG-VN-Glyc, was not altered by the glycosylation. Our findings extend prior work on patterns of Ig V region N-linked glycosylation in autoimmunity to MG subtypes.
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Affiliation(s)
- Caleigh Mandel-Brehm
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA
| | - Miriam L Fichtner
- Department of Neurology, Yale University School of Medicine, New Haven, CT.,Department of Immunobiology, Yale University School of Medicine, New Haven, CT
| | - Ruoyi Jiang
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT
| | - Valerie J Winton
- Proteomics Center of Excellence, Northwestern University, Evanston, IL
| | - Sara E Vazquez
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA
| | - Minh C Pham
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT
| | - Kenneth B Hoehn
- Department of Pathology, Yale University School of Medicine, New Haven, CT
| | - Neil L Kelleher
- Department of Chemistry, Chemistry of Life Processes Institute, Proteomics Center of Excellence at Northwestern University, Evanston, IL.,Department of Molecular Biosciences, Chemistry of Life Processes Institute, Proteomics Center of Excellence at Northwestern University, Evanston, IL
| | - Richard J Nowak
- Department of Neurology, Yale University School of Medicine, New Haven, CT
| | - Steven H Kleinstein
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT.,Department of Pathology, Yale University School of Medicine, New Haven, CT.,Interdepartmental Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT
| | - Michael R Wilson
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, San Francisco, CA; and
| | - Joseph L DeRisi
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA.,Chan Zuckerberg Biohub, San Francisco, CA
| | - Kevin C O'Connor
- Department of Neurology, Yale University School of Medicine, New Haven, CT; .,Department of Immunobiology, Yale University School of Medicine, New Haven, CT
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17
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Oury J, Zhang W, Leloup N, Koide A, Corrado AD, Ketavarapu G, Hattori T, Koide S, Burden SJ. Mechanism of disease and therapeutic rescue of Dok7 congenital myasthenia. Nature 2021; 595:404-408. [PMID: 34163073 PMCID: PMC8277574 DOI: 10.1038/s41586-021-03672-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 05/25/2021] [Indexed: 11/09/2022]
Abstract
Congenital myasthenia (CM) is a devastating neuromuscular disease, and mutations in DOK7, an adaptor protein that is crucial for forming and maintaining neuromuscular synapses, are a major cause of CM1,2. The most common disease-causing mutation (DOK71124_1127 dup) truncates DOK7 and leads to the loss of two tyrosine residues that are phosphorylated and recruit CRK proteins, which are important for anchoring acetylcholine receptors at synapses. Here we describe a mouse model of this common form of CM (Dok7CM mice) and a mouse with point mutations in the two tyrosine residues (Dok72YF). We show that Dok7CM mice had severe deficits in neuromuscular synapse formation that caused neonatal lethality. Unexpectedly, these deficits were due to a severe deficiency in phosphorylation and activation of muscle-specific kinase (MUSK) rather than a deficiency in DOK7 tyrosine phosphorylation. We developed agonist antibodies against MUSK and show that these antibodies restored neuromuscular synapse formation and prevented neonatal lethality and late-onset disease in Dok7CM mice. These findings identify an unexpected cause for disease and a potential therapy for both DOK7 CM and other forms of CM caused by mutations in AGRIN, LRP4 or MUSK, and illustrate the potential of targeted therapy to rescue congenital lethality.
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Affiliation(s)
- Julien Oury
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, NY, USA
| | - Wei Zhang
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, NY, USA
| | - Nadia Leloup
- Perlmutter Cancer Center, NYU Langone Health, New York, NY, USA
| | - Akiko Koide
- Perlmutter Cancer Center, NYU Langone Health, New York, NY, USA
- Department of Medicine, NYU Grossman School of Medicine, New York, NY, USA
| | | | | | - Takamitsu Hattori
- Perlmutter Cancer Center, NYU Langone Health, New York, NY, USA
- Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, USA
| | - Shohei Koide
- Perlmutter Cancer Center, NYU Langone Health, New York, NY, USA.
- Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, USA.
| | - Steven J Burden
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, NY, USA.
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18
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Gastaldi M, Scaranzin S, Businaro P, Mobilia E, Benedetti L, Pesce G, Franciotta D. Improving laboratory diagnostics in myasthenia gravis. Expert Rev Mol Diagn 2021; 21:579-590. [PMID: 33970749 DOI: 10.1080/14737159.2021.1927715] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Introduction: Myasthenia gravis (MG) is a prototypical autoimmune disease, characterized by pathogenic autoantibodies targeting structures of the neuromuscular junction. Radioimmunoprecipitation assays (RIPAs) represent the gold standard for their detection. However, new methods are emerging to complement, or overcome RIPAs, also with the perspective of eliminating the use of radioactive reagents.Areas covered: We discuss advances in laboratory methods, prompted especially by cell-based assays (CBAs), for the detection of the autoantibodies of MG diagnostics, above all those to the nicotinic acetylcholine receptor (AChR), muscle-specific kinase (MuSK), and low molecular-weight receptor-related low-density lipoprotein-4 (LRP4).Expert opinion: CBA technology makes AChRs aggregate on cell membranes, thus allowing to detect autoantibodies to clustered AChRs, with reduction of seronegative MG cases. The diagnostic relevance of RIPA/CBA-measurable LRP4 antibodies is still unclear, in Caucasian patients at least. Live CBAs for the detection of AChR, MuSK, and LRP4 antibodies might represent an alternative to RIPAs, but first require full validation. CBAs could be used as screening tests, limiting RIPAs for antibody quantification. To this end, ELISAs might be an alternative.Fixation procedures preserving enough degree of antigen conformationality could yield AChR and MuSK CBAs suitable for a wide use in clinical-chemistry laboratories.
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Affiliation(s)
- Matteo Gastaldi
- Neuroimmunology Laboratory, IRCCS Mondino Foundation, Pavia, Italy
| | - Silvia Scaranzin
- Neuroimmunology Laboratory, IRCCS Mondino Foundation, Pavia, Italy
| | - Pietro Businaro
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Emanuela Mobilia
- Autoimmunity Laboratory, IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Luana Benedetti
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, Genova, Italy; IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Giampaola Pesce
- Autoimmunity Laboratory, IRCCS Ospedale Policlinico San Martino, Genova, Italy.,Department of Internal Medicine (Dimi), University of Genova, Genova, Italy
| | - Diego Franciotta
- Autoimmunity Laboratory, IRCCS Ospedale Policlinico San Martino, Genova, Italy
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19
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Functional monovalency amplifies the pathogenicity of anti-MuSK IgG4 in myasthenia gravis. Proc Natl Acad Sci U S A 2021; 118:2020635118. [PMID: 33753489 PMCID: PMC8020787 DOI: 10.1073/pnas.2020635118] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
An expanding group of autoimmune diseases is now recognized to be hallmarked by pathogenic IgG4 autoantibodies. IgG4 has the unique ability to exchange Fab-arms, rendering it bispecific and functionally monovalent. Here we show that autoantibody functional monovalency significantly amplifies the pathogenicity of IgG4 autoantibodies using patient-derived monoclonal antibodies in an in vivo model of MuSK myasthenia gravis. Therefore, subclass switching to predominant IgG4 autoantibodies is a critical step in the development of MuSK myasthenia gravis. This new mechanism in autoimmunity is also potentially relevant to 29 other IgG4-mediated autoimmune diseases known to date, allergy and other disease settings where IgG4 antibodies contribute to pathology. Human immunoglobulin (Ig) G4 usually displays antiinflammatory activity, and observations of IgG4 autoantibodies causing severe autoimmune disorders are therefore poorly understood. In blood, IgG4 naturally engages in a stochastic process termed “Fab-arm exchange” in which unrelated IgG4s exchange half-molecules continuously. The resulting IgG4 antibodies are composed of two different binding sites, thereby acquiring monovalent binding and inability to cross-link for each antigen recognized. Here, we demonstrate that this process amplifies autoantibody pathogenicity in a classic IgG4-mediated autoimmune disease: muscle-specific kinase (MuSK) myasthenia gravis. In mice, monovalent anti-MuSK IgG4s caused rapid and severe myasthenic muscle weakness, whereas the same antibodies in their parental bivalent form were less potent or did not induce a phenotype. Mechanistically this could be explained by opposing effects on MuSK signaling. Isotype switching to IgG4 in an autoimmune response thereby may be a critical step in the development of disease. Our study establishes functional monovalency as a pathogenic mechanism in IgG4-mediated autoimmune disease and potentially other disorders.
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