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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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Appeltshauser L, Doppler K. Pan-Neurofascin autoimmune nodopathy - a life-threatening, but reversible neuropathy. Curr Opin Neurol 2023; 36:394-401. [PMID: 37639464 DOI: 10.1097/wco.0000000000001195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
PURPOSE OF REVIEW Autoimmune nodopathies are immune-mediated neuropathies associated with antibodies targeting the peripheral node of Ranvier. Recently, antibodies against all neurofascin-isoforms (pan-neurofascin) have been linked to a clinical phenotype distinct from previously described autoimmune nodopathies. Here, we aim at highlighting the molecular background and the red flags for diagnostic assessment and provide treatment and surveillance approaches for this new disease. RECENT FINDINGS Neurofascin-isoforms are located at different compartments of the node of Ranvier: Neurofascin-186 at the axonal nodal gap, and Neurofascin-155 at the terminal Schwann cell loops at the paranode. Pan-neurofascin antibodies recognize a common epitope on both isoforms and can access the node of Ranvier directly. Depending on their subclass profile, antibodies can induce direct structural disorganization and complement activation. Affected patients present with acute and immobilizing sensorimotor neuropathy, with cranial nerve involvement and long-term respiratory insufficiency. Early antibody-depleting therapy is crucial to avoid axonal damage, and remission is possible despite extended disease and high mortality. The antibody titer and serum neurofilament light chain levels can serve as biomarkers for diagnosis and therapy monitoring. SUMMARY Pan-neurofascin-associated autoimmune nodopathies has unique molecular and clinical features. Testing should be considered in severe and prolonged Guillain-Barré-like phenotype.
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Affiliation(s)
- Luise Appeltshauser
- Department of Neurology, University Hospital Würzburg (UKW), Würzburg, Germany
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Baisya R, Yerram KV, Baby A, Devarasetti PK, Rajasekhar L. Immunoglobulin G4-Related Lesions in Autoimmune Diseases: Unusual Presentations at Atypical Sites-A Tale of 2 Cases with Literature Review. Eur J Rheumatol 2023; 10:169-175. [PMID: 37873667 PMCID: PMC10765183 DOI: 10.5152/eurjrheum.2023.23052] [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: 06/13/2023] [Accepted: 09/13/2023] [Indexed: 10/25/2023] Open
Abstract
Immunoglobulin G4-related disease (IgG4-RD) coexisting with clinically apparent autoimmune diseases, such as rheumatoid arthritis (RA) or antiphospholipid syndrome (APS), is a rarely documented combination in the scientific literature. In this case-based review, we present 2 intriguing cases with preexisting autoimmune diseases, namely, RA and primary APS, who exhibited coexistent IgG4- related lesions at unusual sites. The first case pertains to a patient with known RA who presented with an encasing mass in the esophagus leading to stricture, with histopathological diagnosis of IgG4-RD.The second patient, diagnosed with primary APS, experienced breathlessness, and imaging revealed a right atrial mass. Histopathological examination of the mass confirmed IgG4-RD. Notably, both patients demonstrated significant clinical improvement upon initiation of steroid therapy. Rheumatoid arthritis patients commonly exhibit elevated levels of IgG4 in their sera; however, RA with coexisting IgG4-RD is rarely reported in the literature. Similarly, APS with IgG4-related lesions is exceedingly rare. Although there are few case reports and series on esophageal and cardiac IgG4-RD, the occurrence of such unusual location of IgG4-related lesions in the context of known autoimmunity is presented here for the first time.
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Affiliation(s)
- Ritasman Baisya
- Clinical Immunology and Rheumatology, Nizam’s Institute of Medical Sciences, Hyderabad, India
| | - Keerthi Vardhan Yerram
- Clinical Immunology and Rheumatology, Nizam’s Institute of Medical Sciences, Hyderabad, India
| | - Arun Baby
- Clinical Immunology and Rheumatology, Nizam’s Institute of Medical Sciences, Hyderabad, India
| | - Phani Kumar Devarasetti
- Clinical Immunology and Rheumatology, Nizam’s Institute of Medical Sciences, Hyderabad, India
| | - Liza Rajasekhar
- Clinical Immunology and Rheumatology, Nizam’s Institute of Medical Sciences, Hyderabad, India
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Taieb G, Jentzer A, Vegezzi E, Lleixà C, Illa I, Querol L, Devaux JJ. Effect of monovalency on anti-contactin-1 IgG4. Front Immunol 2023; 14:1021513. [PMID: 36999029 PMCID: PMC10045471 DOI: 10.3389/fimmu.2023.1021513] [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: 08/17/2022] [Accepted: 03/02/2023] [Indexed: 03/15/2023] Open
Abstract
IntroductionAutoimmune nodopathies (AN) have been diagnosed in a subset of patients fulfilling criteria for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) who display no or poor response to intravenous immunoglobulins. Biomarkers of AN are autoantibodies, mainly IgG4, directed against the ternary paranodal complex composed by neurofascin-155, contactin-1 (CNTN1), and Contactin-associated-protein-1 (CASPR1) or against the nodal isoforms of neurofascin. IgG4 can undergo a Fab-arm exchange (FAE) which results in functionally monovalent antibody. This phenomenon differentially affects the pathogenicity of IgG4 depending on the target of autoantibodies. Here, we have evaluated this issue by examining the impact of valency on anti-CNTN1 IgG4 which induces paranodal destruction through a function blocking activity.MethodsSera were obtained from 20 patients with AN associated with anti-CNTN1 antibodies. The proportion of monospecific/bispecific anti-CNTN1 antibodies was estimated in each patient by ELISA by examining the ability of serum antibodies to cross-link untagged CNTN1 with biotinylated CNTN1. To determine the impact of monovalency, anti-CNTN1 IgG4 were enzymatically digested into monovalent Fab and tested in vitro on cell aggregation assay. Also, intraneural injections were performed to determine whether monovalent Fab and native IgG4 may penetrate paranode, and antibody infiltration was monitored 1- and 3-days post injection.Results and discussionWe found that the percentage of monospecific antibodies were lower than 5% in 14 out of 20 patients (70%), suggesting that IgG4 have undergone extensive FAE in situ. The levels of monospecific antibodies correlated with the titers of anti-CNTN1 antibodies. However, no correlation was found with clinical severity, and patients with low or high percentage of monospecific antibodies similarly showed a severe phenotype. Native anti-CNTN1 IgG4 were shown to inhibit the interaction between cells expressing CNTN1/CASPR1 and cells expressing neurofascin-155 using an in vitro aggregation assay. Similarly, monovalent Fab significantly inhibited the interaction between CNTN1/CASPR1 and neurofascin-155. Intraneural injections of Fab and native anti-CNTN1 IgG4 indicated that both mono- and bivalent anti-CNTN1 IgG4 potently penetrated the paranodal regions and completely invaded this region by day 3. Altogether, these data indicate anti-CNTN1 IgG4 are mostly bispecific in patients, and that functionally monovalent anti-CNTN1 antibodies have the pathogenic potency to alter paranode.
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Affiliation(s)
- Guillaume Taieb
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
- Department of Neurology, CHU Montpellier, Hôpital Gui de Chauliac, Montpellier, France
| | - Alexandre Jentzer
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
- Department of Immunology, CHU Montpellier, Hôpital Saint-Eloi, Montpellier, France
| | - Elisa Vegezzi
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Cinta Lleixà
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Barcelona, Spain
| | - Isabel Illa
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Barcelona, Spain
| | - Luis Querol
- Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Barcelona, Spain
| | - Jérôme J. Devaux
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
- *Correspondence: Jérôme J. Devaux,
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Dalmau J, Dalakas MC, Kolson DL, Paul F, Sánchez-Valle R, Zamvil SS. N2 Year in Review. NEUROLOGY(R) NEUROIMMUNOLOGY & NEUROINFLAMMATION 2023; 10:10/1/e200076. [PMID: 36596717 PMCID: PMC9827124 DOI: 10.1212/nxi.0000000000200076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Josep Dalmau
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (J.D., R.S.-V.), Hospital Clínic, Universitat de Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain; Department of Neurology (J.D., D.L.K.), University of Pennsylvania, Philadelphia; Neuroimmunology Unit (M.C.D.), National and Kapodistrian University of Athens Medical School, Greece; Thomas Jefferson University (M.C.D.), Philadelphia, PA; Charité-Universitätsmedizin Berlin und Max Delbrueck Center for Molecular Medicine (F.P.), Germany; and Department of Neurology (S.S.Z.), Weill Institute for Neurosciences and Program in Immunology, University of California, San Francisco.
| | - Marinos C Dalakas
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (J.D., R.S.-V.), Hospital Clínic, Universitat de Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain; Department of Neurology (J.D., D.L.K.), University of Pennsylvania, Philadelphia; Neuroimmunology Unit (M.C.D.), National and Kapodistrian University of Athens Medical School, Greece; Thomas Jefferson University (M.C.D.), Philadelphia, PA; Charité-Universitätsmedizin Berlin und Max Delbrueck Center for Molecular Medicine (F.P.), Germany; and Department of Neurology (S.S.Z.), Weill Institute for Neurosciences and Program in Immunology, University of California, San Francisco
| | - Dennis L Kolson
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (J.D., R.S.-V.), Hospital Clínic, Universitat de Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain; Department of Neurology (J.D., D.L.K.), University of Pennsylvania, Philadelphia; Neuroimmunology Unit (M.C.D.), National and Kapodistrian University of Athens Medical School, Greece; Thomas Jefferson University (M.C.D.), Philadelphia, PA; Charité-Universitätsmedizin Berlin und Max Delbrueck Center for Molecular Medicine (F.P.), Germany; and Department of Neurology (S.S.Z.), Weill Institute for Neurosciences and Program in Immunology, University of California, San Francisco
| | - Friedemann Paul
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (J.D., R.S.-V.), Hospital Clínic, Universitat de Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain; Department of Neurology (J.D., D.L.K.), University of Pennsylvania, Philadelphia; Neuroimmunology Unit (M.C.D.), National and Kapodistrian University of Athens Medical School, Greece; Thomas Jefferson University (M.C.D.), Philadelphia, PA; Charité-Universitätsmedizin Berlin und Max Delbrueck Center for Molecular Medicine (F.P.), Germany; and Department of Neurology (S.S.Z.), Weill Institute for Neurosciences and Program in Immunology, University of California, San Francisco
| | - Raquel Sánchez-Valle
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (J.D., R.S.-V.), Hospital Clínic, Universitat de Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain; Department of Neurology (J.D., D.L.K.), University of Pennsylvania, Philadelphia; Neuroimmunology Unit (M.C.D.), National and Kapodistrian University of Athens Medical School, Greece; Thomas Jefferson University (M.C.D.), Philadelphia, PA; Charité-Universitätsmedizin Berlin und Max Delbrueck Center for Molecular Medicine (F.P.), Germany; and Department of Neurology (S.S.Z.), Weill Institute for Neurosciences and Program in Immunology, University of California, San Francisco
| | - Scott S Zamvil
- From the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) (J.D., R.S.-V.), Hospital Clínic, Universitat de Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA) (J.D.), Barcelona, Spain; Department of Neurology (J.D., D.L.K.), University of Pennsylvania, Philadelphia; Neuroimmunology Unit (M.C.D.), National and Kapodistrian University of Athens Medical School, Greece; Thomas Jefferson University (M.C.D.), Philadelphia, PA; Charité-Universitätsmedizin Berlin und Max Delbrueck Center for Molecular Medicine (F.P.), Germany; and Department of Neurology (S.S.Z.), Weill Institute for Neurosciences and Program in Immunology, University of California, San Francisco
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