1
|
de Oude NL, Hoebeek FE, Ten Brinke MM, de Zeeuw CI, Boele HJ. Pavlovian eyeblink conditioning is severely impaired in tottering mice. J Neurophysiol 2020; 125:398-407. [PMID: 33326350 DOI: 10.1152/jn.00578.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cacna1a encodes the pore-forming α1A subunit of CaV2.1 voltage-dependent calcium channels, which regulate neuronal excitability and synaptic transmission. Purkinje cells in the cortex of cerebellum abundantly express these CaV2.1 channels. Here, we show that homozygous tottering (tg) mice, which carry a loss-of-function Cacna1a mutation, exhibit severely impaired learning in Pavlovian eyeblink conditioning, which is a cerebellar-dependent learning task. Performance of reflexive eyeblinks is unaffected in tg mice. Transient seizure activity in tg mice further corrupted the amplitude of eyeblink conditioned responses. Our results indicate that normal calcium homeostasis is imperative for cerebellar learning and that the oscillatory state of the brain can affect the expression thereof.NEW & NOTEWORTHY In this study, we confirm the importance of normal calcium homeostasis in neurons for learning and memory formation. In a mouse model with a mutation in an essential calcium channel that is abundantly expressed in the cerebellum, we found severely impaired learning in eyeblink conditioning. Eyeblink conditioning is a cerebellar-dependent learning task. During brief periods of brain-wide oscillatory activity, as a result of the mutation, the expression of conditioned eyeblinks was even further disrupted.
Collapse
Affiliation(s)
- Nina L de Oude
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Freek E Hoebeek
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands.,Department for Developmental Origins of Disease, Wilhelmina Children's Hospital, Brain Center, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Chris I de Zeeuw
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands.,Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Henk-Jan Boele
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands.,Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey
| |
Collapse
|
2
|
Fundamental Mechanisms of Autoantibody-Induced Impairments on Ion Channels and Synapses in Immune-Mediated Cerebellar Ataxias. Int J Mol Sci 2020; 21:ijms21144936. [PMID: 32668612 PMCID: PMC7404345 DOI: 10.3390/ijms21144936] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 07/07/2020] [Accepted: 07/09/2020] [Indexed: 12/13/2022] Open
Abstract
In the last years, different kinds of limbic encephalitis associated with autoantibodies against ion channels and synaptic receptors have been described. Many studies have demonstrated that such autoantibodies induce channel or receptor dysfunction. The same mechanism is discussed in immune-mediated cerebellar ataxias (IMCAs), but the pathogenesis has been less investigated. The aim of the present review is to evaluate what kind of cerebellar ion channels, their related proteins, and the synaptic machinery proteins that are preferably impaired by autoantibodies so as to develop cerebellar ataxias (CAs). The cerebellum predictively coordinates motor and cognitive functions through a continuous update of an internal model. These controls are relayed by cerebellum-specific functions such as precise neuronal discharges with potassium channels, synaptic plasticity through calcium signaling pathways coupled with voltage-gated calcium channels (VGCC) and metabotropic glutamate receptors 1 (mGluR1), a synaptic organization with glutamate receptor delta (GluRδ), and output signal formation through chained GABAergic neurons. Consistently, the association of CAs with anti-potassium channel-related proteins, anti-VGCC, anti-mGluR1, and GluRδ, and anti-glutamate decarboxylase 65 antibodies is observed in IMCAs. Despite ample distributions of AMPA and GABA receptors, however, CAs are rare in conditions with autoantibodies against these receptors. Notably, when the autoantibodies impair synaptic transmission, the autoimmune targets are commonly classified into three categories: release machinery proteins, synaptic adhesion molecules, and receptors. This physiopathological categorization impacts on both our understanding of the pathophysiology and clinical prognosis.
Collapse
|
3
|
Mourão LC, Cardoso-Oliveira GP, Braga ÉM. Autoantibodies and Malaria: Where We Stand? Insights Into Pathogenesis and Protection. Front Cell Infect Microbiol 2020; 10:262. [PMID: 32596165 PMCID: PMC7300196 DOI: 10.3389/fcimb.2020.00262] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 05/04/2020] [Indexed: 12/16/2022] Open
Abstract
Autoantibodies are frequently reported in patients with malaria, but whether they contribute to protection or to pathology is an issue of debate. A large body of evidence indicates that antibodies against host-self components are associated to malaria clinical outcomes such as cerebral malaria, renal dysfunction and anemia. Nonetheless, self-reactive immunoglobulins induced during an infection can also mediate protection. In light of these controversies, we summarize here the latest findings in our understanding of autoimmune responses in malaria, focusing on Plasmodium falciparum and Plasmodium vivax. We review the main targets of self-antibody responses in malaria as well as the current, but still limited, knowledge of their role in disease pathogenesis or protection.
Collapse
Affiliation(s)
- Luiza Carvalho Mourão
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Érika Martins Braga
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| |
Collapse
|
4
|
Ménard C, Charnet P, Rousset M, Vignes M, Cens T. Cav2.1 C-terminal fragments produced in Xenopus laevis oocytes do not modify the channel expression and functional properties. Eur J Neurosci 2020; 51:1900-1913. [PMID: 31981388 DOI: 10.1111/ejn.14685] [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: 10/10/2019] [Revised: 01/10/2020] [Accepted: 01/17/2020] [Indexed: 12/01/2022]
Abstract
The sequence and genomic organization of the CACNA1A gene that encodes the Cav2.1 subunit of both P and Q-type Ca2+ channels are well conserved in mammals. In human, rat and mouse CACNA1A, the use of an alternative acceptor site at the exon 46-47 boundary results in the expression of a long Cav2.1 splice variant. In transfected cells, the long isoform of human Cav2.1 produces a C-terminal fragment, but it is not known whether this fragment affects Cav2.1 expression or functional properties. Here, we cloned the long isoform of rat Cav2.1 (Cav2.1(e47)) and identified a novel variant with a shorter C-terminus (Cav2.1(e47s)) that differs from those previously described in the rat and mouse. When expressed in Xenopus laevis oocytes, Cav2.1(e47) and Cav2.1(e47s) displayed similar functional properties as the short isoform (Cav2.1). We show that Cav2.1 isoforms produced short (CT1) and long (CT1(e47)) C-terminal fragments that interacted in vivo with the auxiliary Cavβ4a subunit. Overexpression of the C-terminal fragments did not affect Cav2.1 expression and functional properties. Furthermore, the functional properties of a Cav2.1 mutant without the C-terminal Cavβ4 binding domain (Cav2.1ΔCT2) were similar to those of Cav2.1 and were not influenced by the co-expression of the missing fragments (CT2 or CT2(e47)). Our results exclude a functional role of the C-terminal fragments in Cav2.1 biophysical properties in an expression system widely used to study this channel.
Collapse
Affiliation(s)
- Claudine Ménard
- Institut des Biomolécules Max Mousseron (IBMM), Montpellier, France.,IBMM, Université de Montpellier, Montpellier, France
| | - Pierre Charnet
- Institut des Biomolécules Max Mousseron (IBMM), Montpellier, France.,IBMM, Université de Montpellier, Montpellier, France
| | - Matthieu Rousset
- Institut des Biomolécules Max Mousseron (IBMM), Montpellier, France.,IBMM, Université de Montpellier, Montpellier, France
| | - Michel Vignes
- Institut des Biomolécules Max Mousseron (IBMM), Montpellier, France.,IBMM, Université de Montpellier, Montpellier, France
| | - Thierry Cens
- Institut des Biomolécules Max Mousseron (IBMM), Montpellier, France.,IBMM, Université de Montpellier, Montpellier, France
| |
Collapse
|
5
|
Ambrose PA, Maddison P. Lambert-Eaton myasthenic syndrome and cerebellar ataxia: is Response to immunotherapy a clue to pathogenesis? Muscle Nerve 2018; 58:4-6. [PMID: 29365352 DOI: 10.1002/mus.26079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 01/21/2018] [Accepted: 01/22/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Philip Alexander Ambrose
- Department of Clinical Neurology, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK
| | - Paul Maddison
- Department of Clinical Neurology, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK
| |
Collapse
|
6
|
Abstract
Immune-mediated cerebellar ataxia (CA) comprises a group of rare diseases that are still incompletely described, and are probably underdiagnosed. Both acute and progressive progressions are possible. Different syndromes have been identified, including CA associated with anti-GAD antibodies, the cerebellar type of Hashimoto encephalopathy, primary autoimmune CA, gluten ataxia, opsoclonus-myoclonus syndrome, and paraneoplastic cerebellar degenerations. Most of these syndromes are associated with autoantibodies targeting neuronal antigens. Additionally, autoimmune CA can be triggered by infections, especially in children, and in rare cases occur in the context of an autoimmune multisystem disease, such as systemic lupus erythematosus, sarcoidosis, or Behçet disease. A careful workup is needed to distinguish autoimmune CA from other causes. In adults, a paraneoplastic origin must be ruled out, especially in cases with subacute onset. Neurologic outcome in adults is frequently poor, and optimal therapeutic strategies remain ill defined. The outcome in children is in general good, but children with a poor recovery are on record. The precise pathophysiologic mechanisms even in the presence of detectable autoantibodies are still largely unknown. Further research is needed on both the clinical and mechanistic aspects of immune-mediated CA, and to determine optimal therapeutic strategies.
Collapse
Affiliation(s)
- Bastien Joubert
- French Reference Centre for Paraneoplastic Neurological Syndromes, Lyon Neurological Hospital, Lyon, France; Institut NeuroMyoGene, Université Claude Bernard Lyon 1, Lyon, France
| | - Kevin Rostásy
- Department of Pediatric Neurology, Witten/Herdecke University, Children's Hospital Datteln, Datteln, Germany
| | - Jérôme Honnorat
- French Reference Centre for Paraneoplastic Neurological Syndromes, Lyon Neurological Hospital, Lyon, France; Institut NeuroMyoGene, Université Claude Bernard Lyon 1, Lyon, France.
| |
Collapse
|
7
|
Maddison P, Gozzard P, Grainge MJ, Lang B. Long-term survival in paraneoplastic Lambert-Eaton myasthenic syndrome. Neurology 2017; 88:1334-1339. [DOI: 10.1212/wnl.0000000000003794] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 01/17/2017] [Indexed: 01/19/2023] Open
Abstract
Objective:To establish whether improved tumor survival in patients with Lambert-Eaton myasthenic syndrome (LEMS) and small-cell lung cancer (SCLC) was due to known prognostic risk factors or an effect of LEMS independently, perhaps as a result of circulating factors.Methods:We undertook a prospective observational cohort study of patients with LEMS attending Nottingham University Hospitals, UK, or via the British Neurological Surveillance Unit. In parallel, patients with a new diagnosis of biopsy-proven SCLC were enrolled, examined for neurologic illness, and followed up until death or study end.Results:Between May 2005 and November 2014, we recruited 31 patients with LEMS and SCLC and 279 patients with SCLC without neurologic illness. Allowing for known SCLC survival prognostic factors of disease extent, age, sex, performance status, and sodium values, multivariate Cox regression analysis showed that the presence of LEMS with SCLC conferred a significant survival advantage independently of the other prognostic variables (hazard ratio 1.756, 95% confidence interval 1.137–2.709, p = 0.011).Conclusions:Improved SCLC tumor survival seen in patients with LEMS and SCLC may not be due solely to lead time bias, given that survival advantage remains after allowing for other prognostic factors and that the same degree of survival advantage is not seen in patients with paraneoplastic neurologic syndromes other than LEMS presenting before SCLC diagnosis.
Collapse
|
8
|
Motomura M, Nakata R, Shiraishi H. Lambert-Eaton myasthenic syndrome: Clinical review. ACTA ACUST UNITED AC 2016. [DOI: 10.1111/cen3.12326] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Masakatsu Motomura
- Medical Engineering Course; Department of Engineering; Faculty of Engineering; Nagasaki Institute of Applied Science; Nagasaki Japan
- Department of Neurology and Strokology; Nagasaki University Hospital; Nagasaki Japan
| | - Ruka Nakata
- Department of Neurology and Strokology; Nagasaki University Hospital; Nagasaki Japan
- Department of Neurology; Nagasaki Kita Hospital; Nagasaki Japan
| | - Hirokazu Shiraishi
- Department of Neurology and Strokology; Nagasaki University Hospital; Nagasaki Japan
| |
Collapse
|
9
|
Jain A, Balice-Gordon R. Cellular, synaptic, and circuit effects of antibodies in autoimmune CNS synaptopathies. HANDBOOK OF CLINICAL NEUROLOGY 2016; 133:77-93. [PMID: 27112672 DOI: 10.1016/b978-0-444-63432-0.00005-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Recently, clinicians have identified overlapping but distinguishable encephalitides, each associated with antibodies in serum and cerebrospinal fluid directed against specific cell surface proteins. The antibody targets identified to date are proteins that modulate cell physiology, synaptic transmission, and circuit function. Clinical and laboratory evidence suggests that the anti-cell surface antibodies are not simply markers of disease, but are pathogenic. Patient antibodies to N-methyl-d-aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), or gamma-aminobutyric acid-A (GABAA) receptors cause a loss of cognate receptors from synapses, while recent work has shown that antibodies to GABAB receptors directly antagonize receptor activity. Despite the distinct mechanisms by which patient antibodies abrogate the function of their targets, the resulting pathophysiology leads to abnormal circuit activity and plasticity, which manifests as patient signs and symptoms. Understanding the underlying synaptic and circuit mechanisms of patient autoantibody action may enable clinicians to develop diagnostics and therapies unique to each synaptic autoimmunity subtype, thereby improving patient identification and outcomes.
Collapse
Affiliation(s)
- Ankit Jain
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Rita Balice-Gordon
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA; Neuroscience and Pain Research Unit, Pfizer, Inc., Cambridge, MA, USA.
| |
Collapse
|
10
|
Jarius S, Wildemann B. 'Medusa head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 2: Anti-PKC-gamma, anti-GluR-delta2, anti-Ca/ARHGAP26 and anti-VGCC. J Neuroinflammation 2015; 12:167. [PMID: 26377184 PMCID: PMC4574118 DOI: 10.1186/s12974-015-0357-x] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 07/02/2015] [Indexed: 01/18/2023] Open
Abstract
Serological testing for anti-neural autoantibodies is important in patients presenting with idiopathic cerebellar ataxia, since these autoantibodies may indicate cancer, determine treatment and predict prognosis. While some of them target nuclear antigens present in all or most CNS neurons (e.g. anti-Hu, anti-Ri), others more specifically target antigens present in the cytoplasm or plasma membrane of Purkinje cells (PC). In this series of articles, we provide a detailed review of the clinical and paraclinical features, oncological, therapeutic and prognostic implications, pathogenetic relevance, and differential laboratory diagnosis of the 12 most common PC autoantibodies (often referred to as 'Medusa head antibodies' due their characteristic somatodendritic binding pattern when tested by immunohistochemistry). To assist immunologists and neurologists in diagnosing these disorders, typical high-resolution immunohistochemical images of all 12 reactivities are presented, diagnostic pitfalls discussed and all currently available assays reviewed. Of note, most of these antibodies target antigens involved in the mGluR1/calcium pathway essential for PC function and survival. Many of the antigens also play a role in spinocerebellar ataxia. Part 1 focuses on anti-metabotropic glutamate receptor 1-, anti-Homer protein homolog 3-, anti-Sj/inositol 1,4,5-trisphosphate receptor- and anti-carbonic anhydrase-related protein VIII-associated autoimmune cerebellar ataxia (ACA); part 2 covers anti-protein kinase C gamma-, anti-glutamate receptor delta-2-, anti-Ca/RhoGTPase-activating protein 26- and anti-voltage-gated calcium channel-associated ACA; and part 3 reviews the current knowledge on anti-Tr/delta notch-like epidermal growth factor-related receptor-, anti-Nb/AP3B2-, anti-Yo/cerebellar degeneration-related protein 2- and Purkinje cell antibody 2-associated ACA, discusses differential diagnostic aspects, and provides a summary and outlook.
Collapse
Affiliation(s)
- S Jarius
- Molecular Neuroimmunology Group, Department of Neurology, University of Heidelberg, Otto Meyerhof Center, Im Neuenheimer Feld 350, D-69120, Heidelberg, Germany.
| | - B Wildemann
- Molecular Neuroimmunology Group, Department of Neurology, University of Heidelberg, Otto Meyerhof Center, Im Neuenheimer Feld 350, D-69120, Heidelberg, Germany.
| |
Collapse
|
11
|
Joubert B, Honnorat J. Autoimmune channelopathies in paraneoplastic neurological syndromes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2665-76. [PMID: 25883091 DOI: 10.1016/j.bbamem.2015.04.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 03/10/2015] [Accepted: 04/03/2015] [Indexed: 01/17/2023]
Abstract
Paraneoplastic neurological syndromes and autoimmune encephalitides are immune neurological disorders occurring or not in association with a cancer. They are thought to be due to an autoimmune reaction against neuronal antigens ectopically expressed by the underlying tumour or by cross-reaction with an unknown infectious agent. In some instances, paraneoplastic neurological syndromes and autoimmune encephalitides are related to an antibody-induced dysfunction of ion channels, a situation that can be labelled as autoimmune channelopathies. Such functional alterations of ion channels are caused by the specific fixation of an autoantibody upon its target, implying that autoimmune channelopathies are usually highly responsive to immuno-modulatory treatments. Over the recent years, numerous autoantibodies corresponding to various neurological syndromes have been discovered and their mechanisms of action partially deciphered. Autoantibodies in neurological autoimmune channelopathies may target either directly ion channels or proteins associated to ion channels and induce channel dysfunction by various mechanisms generally leading to the reduction of synaptic expression of the considered channel. The discovery of those mechanisms of action has provided insights on the regulation of the synaptic expression of the altered channels as well as the putative roles of some of their functional subdomains. Interestingly, patients' autoantibodies themselves can be used as specific tools in order to study the functions of ion channels. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.
Collapse
Affiliation(s)
- Bastien Joubert
- University Lyon 1, University Lyon, Rue Guillaume Paradin, 69372 Lyon Cedex 08, France; INSERM, UMR-S1028, CNRS, UMR-5292, Lyon Neuroscience Research Center, Neuro-Oncology and Neuro-Inflammation Team, 7, Rue Guillaume Paradin, Lyon Cedex 08F-69372, France
| | - Jérôme Honnorat
- University Lyon 1, University Lyon, Rue Guillaume Paradin, 69372 Lyon Cedex 08, France; INSERM, UMR-S1028, CNRS, UMR-5292, Lyon Neuroscience Research Center, Neuro-Oncology and Neuro-Inflammation Team, 7, Rue Guillaume Paradin, Lyon Cedex 08F-69372, France; National Reference Centre for Paraneoplastic Neurological Diseases, hospices civils de Lyon, hôpital neurologique, 69677 Bron, France; Hospices Civils de Lyon, Neuro-oncology, Hôpital Neurologique, F-69677 Bron, France.
| |
Collapse
|
12
|
Hajela RK, Huntoon KM, Atchison WD. Lambert-Eaton syndrome antibodies target multiple subunits of voltage-gated Ca2+channels. Muscle Nerve 2014; 51:176-84. [DOI: 10.1002/mus.24295] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Ravindra K. Hajela
- Department of Pharmacology and Toxicology; Michigan State University; B331 Life Sciences Building, 1355 Bogue Street East Lansing Michigan 48824-1317 USA
| | - Kristin M. Huntoon
- Department of Pharmacology and Toxicology; Michigan State University; B331 Life Sciences Building, 1355 Bogue Street East Lansing Michigan 48824-1317 USA
| | - William D. Atchison
- Department of Pharmacology and Toxicology; Michigan State University; B331 Life Sciences Building, 1355 Bogue Street East Lansing Michigan 48824-1317 USA
| |
Collapse
|
13
|
Dallas ML, Deuchars SA, Deuchars J. Immunopharmacology: utilizing antibodies as ion channel modulators. Expert Rev Clin Pharmacol 2014; 3:281-9. [DOI: 10.1586/ecp.10.18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
14
|
Lang B, Willcox N. Autoantibodies in neuromuscular autoimmune disorders. Expert Rev Clin Immunol 2014; 2:293-307. [DOI: 10.1586/1744666x.2.2.293] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
15
|
Rigamonti A, Lauria G, Stanzani L, Mantero V, Andreetta F, Salmaggi A. Non-paraneoplastic voltage-gated calcium channels antibody-mediated cerebellar ataxia responsive to IVIG treatment. J Neurol Sci 2013; 336:169-70. [PMID: 24215945 DOI: 10.1016/j.jns.2013.10.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 10/16/2013] [Accepted: 10/21/2013] [Indexed: 11/15/2022]
Abstract
Non-paraneoplastic cerebellar ataxia associated with voltage-gated calcium channel (VGCC) antibodies is a rare entity with only few cases reported in literature. We describe a 60 year-old man with subacute cerebellar ataxia and subclinical Lambert-Eaton myasthenic syndrome (LEMS) in whom VGCC antibodies were detected at high titer in serum and cerebrospinal fluid. Screening for underlying malignancies was negative. Intravenous immunoglobulin treatment led to the improvement of clinical picture and reduction of serum antibody titer over a 13-month follow-up period. We emphasize that VGCC antibodies should be included in the diagnostic work-up of patients with subacute cerebellar ataxia and that treatment with IVIG can improve the clinical picture and prevent disability.
Collapse
Affiliation(s)
- Andrea Rigamonti
- Department of Neurology, "Alessandro Manzoni" General Hospital, Via Dell'Eremo 9/11, 23900 Lecco, Italy.
| | - Giuseppe Lauria
- Neuromuscular Diseases Unit, IRCCS Foundation "Carlo Besta" Neurological Institute, via Celoria, 11, 20133 Milan, Italy
| | - Lorenzo Stanzani
- Department of Neurology, "Alessandro Manzoni" General Hospital, Via Dell'Eremo 9/11, 23900 Lecco, Italy
| | - Vittorio Mantero
- Department of Neurology, "Alessandro Manzoni" General Hospital, Via Dell'Eremo 9/11, 23900 Lecco, Italy
| | - Francesca Andreetta
- Neuromuscular Diseases Unit, IRCCS Foundation "Carlo Besta" Neurological Institute, via Celoria, 11, 20133 Milan, Italy
| | - Andrea Salmaggi
- Department of Neurology, "Alessandro Manzoni" General Hospital, Via Dell'Eremo 9/11, 23900 Lecco, Italy
| |
Collapse
|
16
|
Briggs SE, Gozzard P, Talbot DC. The association between Lambert-Eaton myasthenic syndrome and small cell lung carcinoma. Immunotargets Ther 2013; 2:31-7. [PMID: 27471686 PMCID: PMC4928366 DOI: 10.2147/itt.s31971] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disorder mediated by autoantibodies to voltage-gated calcium channels. The disorder is diagnosed clinically on the basis of a triad of symptoms (proximal muscle weakness, hyporeflexia, and autonomic disturbance), supported by electrophysiological findings and the presence of autoantibodies. Between 40% and 62% of patients diagnosed with LEMS are found to have small-cell lung cancer (SCLC), almost all of whom develop neurological symptoms before their cancer is diagnosed. Prompt identification of LEMS and appropriate screening for SCLC is key to improving the outcome of both conditions. Here we review the pathophysiology and clinical management of LEMS, focusing particularly on the relationship with SCLC.
Collapse
Affiliation(s)
- Sarah Ew Briggs
- Department of Oncology, Oxford University Hospitals Trust, Churchill Hospital, Oxford, UK
| | - Paul Gozzard
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford UK
| | - Denis C Talbot
- Department of Oncology, Oxford University Hospitals Trust, Churchill Hospital, Oxford, UK
| |
Collapse
|
17
|
Sun H, Li M. Antibody therapeutics targeting ion channels: are we there yet? Acta Pharmacol Sin 2013; 34:199-204. [PMID: 23381110 DOI: 10.1038/aps.2012.202] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The combination of technological advances, genomic sequences and market success is catalyzing rapid development of antibody-based therapeutics. Cell surface receptors and ion channel proteins are well known drug targets, but the latter has seen less success. The availability of crystal structures, better understanding of gating biophysics and validation of physiological roles now form an excellent foundation to pursue antibody-based therapeutics targeting ion channels to treat a variety of diseases.
Collapse
|
18
|
Kleopa KA. Autoimmune channelopathies of the nervous system. Curr Neuropharmacol 2012; 9:458-67. [PMID: 22379460 PMCID: PMC3151600 DOI: 10.2174/157015911796557966] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 03/16/2010] [Accepted: 03/16/2010] [Indexed: 12/20/2022] Open
Abstract
Ion channels are complex transmembrane proteins that orchestrate the electrical signals necessary for normal function of excitable tissues, including the central nervous system, peripheral nerve, and both skeletal and cardiac muscle. Progress in molecular biology has allowed cloning and expression of genes that encode channel proteins, while comparable advances in biophysics, including patch-clamp electrophysiology and related techniques, have made the functional assessment of expressed proteins at the level of single channel molecules possible. The role of ion channel defects in the pathogenesis of numerous disorders has become increasingly apparent over the last two decades. Neurological channelopathies are frequently genetically determined but may also be acquired through autoimmune mechanisms. All of these autoimmune conditions can arise as paraneoplastic syndromes or independent from malignancies. The pathogenicity of autoantibodies to ion channels has been demonstrated in most of these conditions, and patients may respond well to immunotherapies that reduce the levels of the pathogenic autoantibodies. Autoimmune channelopathies may have a good prognosis, especially if diagnosed and treated early, and if they are non-paraneoplastic. This review focuses on clinical, pathophysiologic and therapeutic aspects of autoimmune ion channel disorders of the nervous system.
Collapse
Affiliation(s)
- Kleopas A Kleopa
- Neurology Clinics and Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics, Cyprus
| |
Collapse
|
19
|
Moscato EH, Jain A, Peng X, Hughes EG, Dalmau J, Balice-Gordon RJ. Mechanisms underlying autoimmune synaptic encephalitis leading to disorders of memory, behavior and cognition: insights from molecular, cellular and synaptic studies. Eur J Neurosci 2010; 32:298-309. [PMID: 20646055 DOI: 10.1111/j.1460-9568.2010.07349.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Recently, several novel, potentially lethal and treatment-responsive syndromes that affect hippocampal and cortical function have been shown to be associated with auto-antibodies against synaptic antigens, notably glutamate or GABA-B receptors. Patients with these auto-antibodies, sometimes associated with teratomas and other neoplasms, present with psychiatric symptoms, seizures, memory deficits and decreased levels of consciousness. These symptoms often improve dramatically after immunotherapy or tumor resection. Here we review studies of the cellular and synaptic effects of these antibodies in hippocampal neurons in vitro and preliminary work in rodent models. Our work suggests that patient antibodies lead to rapid and reversible removal of neurotransmitter receptors from synaptic sites, leading to changes in synaptic and circuit function that in turn are likely to lead to behavioral deficits. We also discuss several of the many questions raised by these and related disorders. Determining the mechanisms underlying these novel anti-neurotransmitter receptor encephalopathies will provide insights into the cellular and synaptic bases of the memory and cognitive deficits that are hallmarks of these disorders, and potentially suggest avenues for therapeutic intervention.
Collapse
Affiliation(s)
- Emilia H Moscato
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6074, USA
| | | | | | | | | | | |
Collapse
|
20
|
Chillar A, Wu J, Cervantes V, Ruan KH. Structural and Functional Analysis of the C-Terminus of Gαq in Complex with the Human Thromboxane A2 Receptor Provides Evidence of Constitutive Activity. Biochemistry 2010; 49:6365-74. [DOI: 10.1021/bi100047n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Annirudha Chillar
- Center for Experimental Therapeutics and Pharmacoinformatics, Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, Texas 77204
| | - Jiaxin Wu
- Center for Experimental Therapeutics and Pharmacoinformatics, Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, Texas 77204
| | - Vanessa Cervantes
- Center for Experimental Therapeutics and Pharmacoinformatics, Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, Texas 77204
| | - Ke-He Ruan
- Center for Experimental Therapeutics and Pharmacoinformatics, Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, Texas 77204
| |
Collapse
|
21
|
Pellkofer HL, Voltz R, Kuempfel T. Favorable response to rituximab in a patient with anti-VGCC-positive Lambert-Eaton myasthenic syndrome and cerebellar dysfunction. Muscle Nerve 2009; 40:305-8. [PMID: 19609921 DOI: 10.1002/mus.21315] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disease that is characterized by impaired transmission across the neuromuscular junction due to autoantibodies directed against the presynaptic voltage-gated calcium channels (VGCC-ab). Clinical symptoms are usually characterized by proximal muscle weakness and mild dysautonomia. In some patients there are signs of cerebellar dysfunction as well, usually associated with cancer. Here we report the long-term follow-up of a patient with VGCC-ab-positive LEMS and a severe cerebellar syndrome but without evidence of cancer over 5 years. While conventional immunosuppressive therapy (steroids, azathioprine) failed, he improved with plasma exchange and consecutive treatment with rituximab. Muscle Nerve 40: 305-308, 2009.
Collapse
Affiliation(s)
- Hannah L Pellkofer
- Institute of Clinical Neuroimmunology, Ludwig Maximilians University, Campus Grosshadern, Marchioninistr. 15, D-81377 Munich, Germany.
| | | | | |
Collapse
|
22
|
|
23
|
Purkinje cell input to cerebellar nuclei in tottering: ultrastructure and physiology. THE CEREBELLUM 2008; 7:547-58. [PMID: 19082682 DOI: 10.1007/s12311-008-0086-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2008] [Accepted: 11/17/2008] [Indexed: 10/21/2022]
Abstract
Homozygous tottering mice are spontaneous ataxic mutants, which carry a mutation in the gene encoding the ion pore of the P/Q-type voltage-gated calcium channels. P/Q-type calcium channels are prominently expressed in Purkinje cell terminals, but it is unknown to what extent these inhibitory terminals in tottering mice are affected at the morphological and electrophysiological level. Here, we investigated the distribution and ultrastructure of their Purkinje cell terminals in the cerebellar nuclei as well as the activities of their target neurons. The densities of Purkinje cell terminals and their synapses were not significantly affected in the mutants. However, the Purkinje cell terminals were enlarged and had an increased number of vacuoles, whorled bodies, and mitochondria. These differences started to occur between 3 and 5 weeks of age and persisted throughout adulthood. Stimulation of Purkinje cells in adult tottering mice resulted in inhibition at normal latencies, but the activities of their postsynaptic neurons in the cerebellar nuclei were abnormal in that the frequency and irregularity of their spiking patterns were enhanced. Thus, although the number of their terminals and their synaptic contacts appear quantitatively intact, Purkinje cells in tottering mice show several signs of axonal damage that may contribute to altered postsynaptic activities in the cerebellar nuclei.
Collapse
|
24
|
Urbano FJ, Pagani MR, Uchitel OD. Calcium channels, neuromuscular synaptic transmission and neurological diseases. J Neuroimmunol 2008; 201-202:136-44. [PMID: 18678414 DOI: 10.1016/j.jneuroim.2008.06.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 06/16/2008] [Accepted: 06/17/2008] [Indexed: 01/20/2023]
Abstract
Voltage-dependent calcium channels are essential in neuronal signaling and synaptic transmission, and their functional alterations underlie numerous human disorders whether monogenic (e.g., ataxia, migraine, etc.) or autoimmune. We review recent work on Ca(V)2.1 or P/Q channelopathies, mostly using neuromuscular junction preparations, and focus specially on the functional hierarchy among the calcium channels recruited to mediate neurotransmitter release when Ca(V)2.1 channels are mutated or depleted. In either case, synaptic transmission is greatly compromised; evidently, none of the reported functional replacements with other calcium channels compensates fully.
Collapse
Affiliation(s)
- Francisco J Urbano
- Laboratorio de Fisiología y Biología Molecular, Instituto de Fisiología y Biología Molecular y Neurociencias, Universidad de Buenos Aires-CONICET, Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, C1428-Buenos Aires, Argentina
| | | | | |
Collapse
|
25
|
Paraneoplastic neurological autoimmunity and survival in small-cell lung cancer. J Neuroimmunol 2008; 201-202:159-62. [PMID: 18667241 DOI: 10.1016/j.jneuroim.2008.05.024] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 04/17/2008] [Accepted: 05/08/2008] [Indexed: 11/20/2022]
Abstract
The autoimmune disorder of Lambert-Eaton myasthenic syndrome (LEMS) associates with small cell lung carcinoma (SCLC) in 50-60% of cases. It has been postulated that patients who harbour paraneoplastic neurological syndromes such as LEMS have an improved tumour prognosis compared to other patients with the tumour but without neurological deficit. In this intermediate report of an ongoing prospective study, 100 consecutive patients with biopsy-proven SCLC underwent full neurological examination and serum was taken for autoantibody analysis. Antibodies to voltage-gated calcium channels were detected in 10 patients, however only 4 had clinical and electrophysiological features of LEMS, 1 had limbic encephalitis, whilst the remaining 5 had no neurological signs. A further 6 patients had onconeural antibodies; only one had a paraneoplastic syndrome, sensory neuropathy. The median survival of the four antibody positive LEMS patients (19.6 months) was considerably greater than that for the antibody negative (8.9 months) or antibody positive patients as a whole (10.5 months). Although preliminary, these results suggest that functionally effective antibodies present in the sera of patients with LEMS may confer a survival advantage.
Collapse
|
26
|
Takamori M. Lambert-Eaton myasthenic syndrome: search for alternative autoimmune targets and possible compensatory mechanisms based on presynaptic calcium homeostasis. J Neuroimmunol 2008; 201-202:145-52. [PMID: 18653248 DOI: 10.1016/j.jneuroim.2008.04.040] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 03/28/2008] [Accepted: 04/01/2008] [Indexed: 10/21/2022]
Abstract
The Lambert-Eaton myasthenic syndrome (LEMS) is a disease of neuromuscular transmission in which autoantibodies against the P/Q-type voltage-gated calcium channel (VGCC) at the presynaptic nerve terminal play a major role in decreasing quantal release of acetylcholine (ACh), resulting in skeletal muscle weakness and autonomic symptoms. It is associated with cancer, particularly small-cell lung carcinoma (SCLC), in 50-60% of LEMS patients; the nerve terminal and carcinoma cells apparently share a common antigen (VGCC), suggesting an immunological cross-reactivity that may lead to the neurological abnormality. Non-tumor LEMS has a strong association with HLA-DR3-B8. In approximately 15% of LEMS patients, no anti-P/Q-type VGCC antibodies are found, suggesting recognition of other targets(s). The VGCC-associated protein synaptotagmin could be one candidate, because it acts as an exocytotic calcium receptor, is implicated in fast ACh release; its N-terminus is exposed extracellularly during exocytosis and it is expressed in SCLC. Antibodies against synaptotagmin-1 were detected in both anti-VGCC-positive and -negative LEMS patients (20%), and it can be immunogenic, allowing induction of an animal model of LEMS. Another candidate target is the M1-type presynaptic muscarinic ACh receptor (M1 mAChR), also expressed extracellularly on motor nerve terminals; it modulates cholinergic transmission, linking to P/Q-type VGCC. In our series of 25 LEMS patients with and without SCLC, anti-M1 mAChR antibodies were prevalent in both anti-VGCC-positive and -negative LEMS patients. Autonomic symptoms seemed more frequent in the latter; serum from one of them passively transferred LEMS-type electrophysiological defects to mice. As a compensatory mechanism, researchers in Oxford suggested a shift in the dependence of ACh release from the P/Q-type to other types of VGCC. We have also focused on G protein-coupled mAChRs and neurotrophins, which may affect both P/Q-type VGCC and clathrin-independent "kiss-and-run" synaptic vesicle recycling (fast-mode of endocytosis) via protein kinase C activation. We hypothesize that these signaling cascades help to compensate for the immune-mediated defects in calcium entry in LEMS, compensation that may frequently be restricted by the coincident anti-M1 mAChR antibodies in this disease.
Collapse
Affiliation(s)
- Masaharu Takamori
- Neurological Center, Kanazawa-Nishi Hospital and Kanazawa University, 6-15-41, Ekinishi Honmachi, Kanazawa 920-0025, Japan.
| |
Collapse
|
27
|
Martin-Moutot N, De Haro L, Seagar M. Distinct evolution of calcium channel antibody types in Lambert-Eaton myasthenic syndrome. J Neuroimmunol 2008; 197:47-53. [PMID: 18474401 DOI: 10.1016/j.jneuroim.2008.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Revised: 03/17/2008] [Accepted: 04/01/2008] [Indexed: 02/06/2023]
Abstract
To determine whether titers of anti-P/Q type and anti-N type calcium channel antibodies provide distinct information, both types of assay were performed during follow-up of 7 patients with Lambert-Eaton myasthenic syndrome (LEMS). In 4 patients with both antibody responses, titers evolved independently and often in an inverse relationship. Two patients with squamous cell lung carcinoma (SqCLC) produced anti-N type channel antibodies, but no detectable anti-P/Q channel responses. These results suggest that anti-N channel autoantibodies constitute an immune response distinct from the anti-P/Q type channel specificity and can also correlate with clinical evolution. Consequently combined assays may provide more comprehensive information during follow-up of LEMS.
Collapse
|
28
|
Lorenzoni PJ, Scola RH, Lang B, Kay CSK, Teive HAG, Kowacs PA, Werneck LC. Cerebellar ataxia in non-paraneoplastic Lambert-Eaton myasthenic syndrome. J Neurol Sci 2008; 270:194-6. [PMID: 18374949 DOI: 10.1016/j.jns.2008.02.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 02/05/2008] [Accepted: 02/07/2008] [Indexed: 11/29/2022]
Abstract
Lambert-Eaton myasthenic syndrome (LEMS) is an immune-mediated disorder of the neuromuscular junction that rarely is associated with cerebellar ataxia (CA). We describe two patients with non-paraneoplastic LEMS associated with CA who showed high levels of anti-P/Q-type voltage-gated calcium channels antibodies in the serum and cerebrospinal fluid, and reduced CMAP with increment after brief maximum voluntary contraction in electrophysiological studies. We suggest that LEMS should be considered in the differential diagnosis of patients with CA.
Collapse
Affiliation(s)
- Paulo J Lorenzoni
- Department of Internal Medicine, Universidade Federal do Paraná, Curitiba, Brazil
| | | | | | | | | | | | | |
Collapse
|
29
|
Anti-Ca2+ channel antibody attenuates Ca2+ currents and mimics cerebellar ataxia in vivo. Proc Natl Acad Sci U S A 2008; 105:2705-10. [PMID: 18272482 DOI: 10.1073/pnas.0710771105] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Voltage-gated Ca(2+) channels (VGCCs) are membrane proteins that determine the activity and survival of neurons, and mutations in the P/Q-type VGCCs are known to cause cerebellar ataxia. VGCC dysfunction may also underlie acquired peripheral and central nervous system diseases associated with small-cell lung cancer, including Lambert-Eaton myasthenic syndrome (LEMS) and paraneoplastic cerebellar ataxia (PCA). The pathogenic role of anti-VGCC antibody in LEMS is well established. Although anti-VGCC antibody is also found in a significant fraction of PCA patients, its contribution to PCA is unclear. Using a polyclonal peptide antibody against a major immunogenic region in P/Q-type VGCCs (the extracellular Domain-III S5-S6 loop), we demonstrated that such antibody was sufficient to inhibit VGCC function in neuronal and recombinant VGCCs, alter cerebellar synaptic transmission, and confer the phenotype of cerebellar ataxia. Our data support the hypothesis that anti-VGCC antibody may play a significant role in the pathogenesis of cerebellar dysfunction in PCA.
Collapse
|
30
|
Vincent A. Autoantibodies in different forms of myasthenia gravis and in the Lambert-Eaton syndrome. HANDBOOK OF CLINICAL NEUROLOGY 2008; 91:213-227. [PMID: 18631844 DOI: 10.1016/s0072-9752(07)01506-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Angela Vincent
- Department of Clinical Neurology, University of Oxford, Oxford, UK.
| |
Collapse
|
31
|
Kaja S, van de Ven RCG, Broos LAM, Frants RR, Ferrari MD, van den Maagdenberg AMJM, Plomp JJ. Characterization of acetylcholine release and the compensatory contribution of non-Cav2.1 channels at motor nerve terminals of leaner Cav2.1-mutant mice. Neuroscience 2007; 144:1278-87. [PMID: 17161543 DOI: 10.1016/j.neuroscience.2006.11.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Revised: 11/01/2006] [Accepted: 11/04/2006] [Indexed: 11/23/2022]
Abstract
The severely ataxic and epileptic mouse leaner (Ln) carries a natural splice site mutation in Cacna1a, leading to a C-terminal truncation of the encoded Ca(v)2.1 alpha(1) protein. Ca(v)2.1 is a neuronal Ca(2+) channel, mediating neurotransmitter release at many central synapses and the peripheral neuromuscular junction (NMJ). With electrophysiological analyses we demonstrate severely reduced ( approximately 50%) neurotransmitter release at Ln NMJs. This equals the reduction at NMJs of Cacna1a null-mutant (Ca(v)2.1-KO) mice, which display a neurological phenotype remarkably similar to that of Ln mice. However, using selective Ca(v) channel blocking compounds we revealed a compensatory contribution profile of non-Ca(v)2.1 type channels at Ln NMJs that differs completely from that at Ca(v)2.1-KO NMJs. Our data indicate that the residual function and presence of Ln-mutated Ca(v)2.1 channels precludes presynaptic compensatory recruitment of Ca(v)1 and Ca(v)2.2 channels, and hampers that of Ca(v)2.3 channels. This is the first report directly showing at single synapses the deficits and plasticity in transmitter release resulting from the Ln mutation of Cacna1a.
Collapse
Affiliation(s)
- S Kaja
- Department of Neurology, Leiden University Medical Centre, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | | | | | | | | | | | | |
Collapse
|
32
|
Voltage-gated calcium channels, calcium signaling, and channelopathies. CALCIUM - A MATTER OF LIFE OR DEATH 2007. [DOI: 10.1016/s0167-7306(06)41005-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
|
33
|
Tringham EW, Payne CE, Dupere JRB, Usowicz MM. Maturation of rat cerebellar Purkinje cells reveals an atypical Ca2+ channel current that is inhibited by omega-agatoxin IVA and the dihydropyridine (-)-(S)-Bay K8644. J Physiol 2006; 578:693-714. [PMID: 17124267 PMCID: PMC2151333 DOI: 10.1113/jphysiol.2006.121905] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
To determine if the properties of Ca2+ channels in cerebellar Purkinje cells change during postnatal development, we recorded Ca2+ channel currents from Purkinje cells in cerebellar slices of mature (postnatal days (P) 40-50) and immature (P13-20) rats. We found that at P40-50, the somatic Ca2+ channel current was inhibited by omega-agatoxin IVA at concentrations selective for P-type Ca2+ channels (approximately 85%; IC50, <1 nM) and by the dihydropyridine (-)-(S)-Bay K8644 (approximately 70%; IC50, approximately 40 nM). (-)-(S)-Bay K8644 is known to activate L-type Ca2+ channels, but the decrease in current was not secondary to the activation of L-type channels because inhibition by (-)-(S)-Bay K8644 persisted in the presence of the L-type channel blocker (R,S)-nimodipine. By contrast, at P13-20, the current was inhibited by omega-agatoxin IVA (approximately 86%; IC50, approximately 1 nM) and a minor component was inhibited by (R,S)-nimodipine (approximately 8%). The dihydropyridine (-)-(S)-Bay K8644 had no clear effect when applied alone, but in the presence of (R,S)-nimodipine it reduced the current (approximately 40%), suggesting that activation of L-type channels by (-)-(S)-Bay K8644 masks its inhibition of non-L-type channels. Our findings indicate that Purkinje neurons express a previously unrecognized type of Ca2+ channel that is inhibited by omega-agatoxin IVA, like prototypical P-type channels, and by (-)-(S)-Bay K8644, unlike classical P-type or L-type channels. During maturation, there is a decrease in the size of the L-type current and an increase in the size of the atypical Ca2+ channel current. These changes may contribute to the maturation of the electrical properties of Purkinje cells.
Collapse
Affiliation(s)
- Elizabeth W Tringham
- Department of Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | | | | | | |
Collapse
|
34
|
Abstract
Ion channels are crucial elements in neuronal signaling and synaptic transmission, and defects in their function are known to underlie rare genetic disorders, including some forms of epilepsy. A second class of channelopathies, characterized by autoantibodies against ligand- and voltage-gated ion channels, cause a variety of defects in peripheral neuromuscular and ganglionic transmission. There is also emerging evidence for autoantibody-mediated mechanisms in subgroups of patients with central nervous system disorders, particularly those involving defects in cognition or sleep and often associated with epilepsy. In all autoimmune channelopathies, the relationship between autoantibody specificity and clinical phenotype is complex. But with this new information, autoimmune channelopathies are detected and treated with increasing success, and future research promises new insights into the mechanisms of dysfunction at neuronal synapses and the determinants of clinical phenotype.
Collapse
Affiliation(s)
- Angela Vincent
- Neurosciences Group, Department of Clinical Neurology, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom.
| | | | | |
Collapse
|
35
|
Scoggan KA, Friedman JH, Bulman DE. CACNA1A mutation in a EA-2 patient responsive to acetazolamide and valproic acid. Can J Neurol Sci 2006; 33:68-72. [PMID: 16583725 DOI: 10.1017/s0317167100004728] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Episodic ataxia type-2 (EA-2) is an autosomal dominant neurological disorder that has been shown to result from mutations in the CACNA1A gene encoding the P/Q-type calcium channel. Affected individuals experience episodes of cerebellar ataxia usually associated with migraine symptoms, interictal nystagmus, mild residual and in some cases a progressive cerebellar incoordination and respond to acetazolamide treatment. We identified a patient with a positive family history for episodic ataxia, who was originally diagnosed with epilepsy and treated with valproic acid. Subsequent examination revealed that the symptoms were consistent with a diagnosis of EA-2. The patient responded positively to a combination of acetazolamide and valproic acid. Molecular genetic analysis of the CACNA1A gene was performed in order to confirm a diagnosis of EA-2. METHODS The CACNA1A gene was evaluated for mutations using single strand conformational polymorphism analysis and direct DNA sequencing. Allele specific oligo hybridization was used to confirm that the mutation was segregating with only affected family members and was not present in the control group. RESULTS In this study we identified a new missense mutation in exon 12 of the CACNA1A gene from a patient with EA-2 whose symptoms could be controlled with a combination of acetazolamide and valproic acid. This G to A transition changes a highly conserved glutamic acid residue to a lysine residue in domain II S2 of the P/Q-type calcium channel alpha1A subunit. CONCLUSIONS The use of valproic acid in treating patients with EA-2 is not well documented. Here we describe a patient with a novel mutation in the CACNA1A gene who responded positively to a combination of acetazolamide and valproic acid.
Collapse
|
36
|
Kaja S, Van de Ven RCG, Ferrari MD, Frants RR, Van den Maagdenberg AMJM, Plomp JJ. Compensatory Contribution of Cav2.3 Channels to Acetylcholine Release at the Neuromuscular Junction ofTotteringMice. J Neurophysiol 2006; 95:2698-704. [PMID: 16381801 DOI: 10.1152/jn.01221.2005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tottering ( Tg) mice carry the mutation P601L in their Cacna1a encoded Cav2.1 channels. Transmitter release at the wild-type neuromuscular junction (NMJ) is almost exclusively mediated by Cav2.1 channels, and we used this model synapse to study synaptic consequences of the Tg mutation. With electrophysiology, and using subtype-specific Cav2 channel-blocking toxins, we assessed a possible compensatory contribution of non-Cav2.1 channels to evoked acetylcholine (ACh) release at Tg NMJs. Release was reduced by ∼75% by the Cav2.1 channel blocker ω-agatoxin-IVA, which was less than the ∼95% reduction observed in wild-type. Release at Tg NMJs, but not at wild-type synapses, was reduced by ∼15% by SNX-482, a Cav2.3 channel blocker. No Cav2.2 channel involvement was found. Probably, there is a small reduction in functional presynaptic Cav2.1 channels at Tg NMJs, which is compensated for by Cav2.3 channels. The remaining Cav2.1 channels are likely to convey enlarged Ca2+flux, because evoked ACh release at Tg NMJs, at low extracellular Ca2+concentration, was approximately sixfold higher than at wild-type NMJs. This is the first report of compensatory expression of non-Cav2.1 channels at NMJs of mice with a single amino acid change in Cav2.1.
Collapse
Affiliation(s)
- Simon Kaja
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
| | | | | | | | | | | |
Collapse
|
37
|
Fabien N, Monier JC. [Antireceptor and antichannel autoantibodies]. ACTA ACUST UNITED AC 2006; 54:362-9. [PMID: 16540262 DOI: 10.1016/j.patbio.2005.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Accepted: 12/21/2005] [Indexed: 10/24/2022]
Abstract
This review of literature concerns the different autoantibodies directed against membrane receptors and ion channels. The target antigens, the associated pathologies, the pathogenesis and the methods of detection of these autoantibodies will be addressed. Some of these autoantibodies are thought to be closely related to the autoimmune disease whereas for some others their pathogenesis role is still unclear. Overall, the roles of antibodies are different between diseases, but the presence of such autoantibodies support the basis of intervening immunotherapy, antibody titers predicted the activity of the diseases and some of them are very specific and become the useful markers for the diagnosis. Some autoantibodies are detected routinely as the antiacetylcholine receptor, voltage-gated potassium and calcium channels autoantibodies whereas most of them are detected very rarely and only by specialized laboratories. This review will be divided in three parts with the following classification: the first group of autoantibodies directed against membrane receptors included receptors with an enzymatic activity (mostly tyrosine kinase) with one transmembrane domain, receptors associated to G protein with seven transmembrane domains, ion channels and receptors associated to the membrane by the glycosyl phosphatidyl inositol and the second group of intracellular receptor autoantibodies directed to the estrogens, androgens, lamin and kinesin receptors.
Collapse
Affiliation(s)
- N Fabien
- Laboratoire d'immunologie, unité fonctionnelle Auto-immunité, bâtiment 1G, centre hospitalier Lyon-Sud, 69495 Pierre-Bénite cedex, France.
| | | |
Collapse
|
38
|
Korfei M, Fühlhuber V, Schmidt-Wöll T, Kaps M, Preissner KT, Blaes F. Functional characterisation of autoantibodies from patients with pediatric opsoclonus–myoclonus-syndrome. J Neuroimmunol 2005; 170:150-7. [PMID: 16203043 DOI: 10.1016/j.jneuroim.2005.08.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Accepted: 08/22/2005] [Indexed: 11/22/2022]
Abstract
Paraneoplastic opsoclonus-myoclonus-syndrome (OMS) both in children and adults is suspected to be the result of an autoimmune response directed against cross-reactive proteins of tumor and neuronal cells. We here characterised the binding and functional activities of anti-neuroblastoma antibodies in IgG fractions from 11 OMS children with and without neuroblastoma. IgG fractions from neuroblastoma without OMS (NB) and healthy children served as controls. Indirect immunofluorescence and Western blot revealed IgG binding to intracellular autoantigens in all OMS patients, but in only one of the controls (p<0.001). Using flow cytometry, we could demonstrate surface binding of IgG fractions in all OMS patients, but only in one of control (p<0.001). Moreover OMS IgG exhibited a significant anti-proliferative and a cytotoxic effect on neuroblastoma cells compared to control IgG (p<0.001 and p<0.01). TUNEL assay revealed increased apoptotic cell death of the neuroblastoma cells after exposure to OMS IgG, but not to NB or control IgG (p<0.01). Preabsorption of membrane binding abandoned the anti-proliferative effect of OMS IgG. These findings indicate that surface-binding autoantibodies are present in OMS patients and these autoantibodies cause inhibition of cell proliferation and induce apoptosis.
Collapse
Affiliation(s)
- Martina Korfei
- Department of Neurology, Am Steg 14, Justus-Liebig-University, D-35385 Giessen, Germany
| | | | | | | | | | | |
Collapse
|
39
|
Buckley C, Vincent A. Autoimmune channelopathies. ACTA ACUST UNITED AC 2005; 1:22-33. [PMID: 16932489 DOI: 10.1038/ncpneuro0033] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2005] [Accepted: 08/18/2005] [Indexed: 12/19/2022]
Abstract
Autoimmune disorders of the neuromuscular junction remain a paradigm for our understanding of autoimmunity. Since the role of autoantibodies to acetylcholine receptors in the pathogenesis of myasthenia gravis was first recognized in the 1970s, a range of antibody-mediated disorders of the neuromuscular junction have been described, each associated with an autoantibody to a specific ligand-gated receptor, voltage-gated ion channel or related protein. In addition, antibodies to a ganglionic form of acetylcholine receptor have been detected in autoimmune forms of autonomic neuropathy. In the past few years, a role for antibodies in disorders of the CNS has begun to emerge, challenging our previous concepts regarding the blood-brain barrier and the role of the humoral immune system in CNS pathology. Although it has not yet been definitively shown that these CNS conditions are antibody-mediated, the detection of the specific antibody supports a trial of immunosuppressive therapy to which many patients appear to respond. In this article, we review the roles of antibodies to receptors and ion channels in the peripheral and central nervous systems, concentrating on the recently defined autonomic and CNS conditions and on the role of antibody measurement in diagnosis and management.
Collapse
|
40
|
Kamp MA, Krieger A, Henry M, Hescheler J, Weiergräber M, Schneider T. Presynaptic ‘Cav2.3-containing’ E-type Ca2+channels share dual roles during neurotransmitter release. Eur J Neurosci 2005; 21:1617-25. [PMID: 15845089 DOI: 10.1111/j.1460-9568.2005.03984.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ca2+ influx into excitable cells is a prerequisite for neurotransmitter release and regulated exocytosis. Within the group of ten cloned voltage-gated Ca2+ channels, the Ca(v)2.3-containing E-type Ca2+ channels are involved in various physiological processes, such as neurotransmitter release and exocytosis together with other voltage-gated Ca2+ channels of the Ca(v)1, Ca(v)2 and Ca(v)3 subfamily. However, E-type Ca2+ channels also exhibit several subunit-specific features, most of which still remain poorly understood. Ca(v)2.3-containing R-type channels (here called 'E-type channels') are also located in presynaptic terminals and interact with some synaptic vesicle proteins, the so-called SNARE proteins, although lacking the classical synprint interaction site. E-type channels trigger exocytosis and are also involved in long-term potentiation. Recently, it was shown that the interaction of Ca(v)2.3 with the EF-hand motif containing protein EFHC1 is involved in the aetiology and pathogenesis of juvenile myoclonic epilepsy.
Collapse
Affiliation(s)
- M A Kamp
- Institute of Neurophysiology, Robert-Koch-Str. 39, D-50931 Köln, Germany
| | | | | | | | | | | |
Collapse
|
41
|
Billiau AD, Wouters CH, Lagae LG. Epilepsy and the immune system: is there a link? Eur J Paediatr Neurol 2005; 9:29-42. [PMID: 15701565 DOI: 10.1016/j.ejpn.2004.10.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Revised: 10/27/2004] [Accepted: 10/28/2004] [Indexed: 11/28/2022]
Abstract
The concept that the immune system plays a role in the epileptogenic process of some epileptic syndromes was first proposed more than 20 years ago. Since then, numerous studies have reported on the existence of a variety of immunological alterations in epileptic patients, on the observation of favourable responses of refractory epilepsy syndromes to immunomodulatory treatment, and on the association of certain well-known immune-mediated disease states with epilepsy. This review comprehensively recapitulates the currently available evidence supporting or arguing against the possible involvement of the immune system in the pathogenesis of certain types of epilepsy. It is concluded that an abundance of facts is in support of this concept and that further studies should be directed at substantiating the pathogenic significance of (auto)immune responses in certain types of epilepsy. Current progress in the functional and molecular immunological research techniques will indisputably contribute to the elucidation of this link.
Collapse
Affiliation(s)
- An D Billiau
- Pediatric Rheumatology Department, University Hospital Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium.
| | | | | |
Collapse
|
42
|
Abstract
The Lambert-Eaton Myasthenic Syndrome (LEMS) is characterised by proximal muscle weakness initially affecting gait, autonomic symptoms (dry mouth, constipation, erectile failure), augmentation of strength during initial voluntary activation, and depressed tendon reflexes with post-tetanic potentiation. The disorder is paraneoplastic (small cell lung cancer) in about 60p. cent (P-LEMS); no cancer is associated in the remainder (NP-LEMS). LEMS affects all races. NP-LEMS can occur in childhood as well as adult life; P-LEMS is unusual at<30 Years. The weakness results from a reduction in the quantal release of acetylcholine from motor nerve terminals, caused by autoantibodies to P/Q-type voltage-gated calcium channels (VGCCs) that are provoked by tumour VGCCs in P-LEMS; the stimulus in NP-LEMS is not known. These antibodies may be implicated in the rarely associated cerebellar degeneration. The diagnosis can be confirmed by detecting the specific antibody in a radioimmunoprecipitation assay, and by finding a reduced compound muscle action potential amplitude that increases by>100p. cent following maximum voluntary activation. Most patients benefit from 3,4-diaminopyridine; pyridostigmine is less effective. Specific tumour therapy in P-LEMS will often ameliorate the neurological disorder. In those with severe weakness, IVIg or plasmapheresis confers short-term benefits. Prednisone alone or combined with azathioprine or cyclosporin can achieve long-term control of the disorder.
Collapse
Affiliation(s)
- J Newsom-Davis
- Department of Clinical Neurology, University of Oxford, Grande-Bretagne.
| |
Collapse
|
43
|
Martin-Moutot N, de Haro L, Seagar M. Dosage et spécificité d’autoanticorps anti-canaux calcium dans le syndrome myasthénique de Lambert-Eaton. Rev Neurol (Paris) 2004; 160:S28-34. [PMID: 15269657 DOI: 10.1016/s0035-3787(04)71002-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune channelopathy in which patients produce autoantibodies directed against voltage-gated calcium channels. Autoantibodies down-regulate calcium channels resulting in reduced transmitter release, which in turn leads to muscular weakness and autonomic dysfunction. LEMS is paraneoplastic in 60-70% of patients, most frequently associated with small cell lung carcinoma (SCLC). SCLC lines express many neuronal and neuroendocrine proteins including neuronal calcium channels of the Cav2 family (P/Q and N-type channels). It is thus likely that the paraneoplastic form of LEMS is the consequence of an anti-tumoral immune response and the production of antibodies that cross-react with identical or homologous antigens in nerve terminals. Neurological symptoms generally appear several Months before detection of the tumor. Consequently correct diagnosis of LEMS is crucial as it can allow early treatment of a particularly aggressive carcinoma. Based on published studies, our laboratory has set-up serological assays for LEMS autoantibodies as an aid to diagnosis. Calcium channels in detergent extracts of rat brain or cerebellum membranes were labeled with radioligands specific for N-type (125I-omega conotoxin GVIA) or P/Q-type (125I-omega conotoxin MVIIC) calcium channels. Autoantibodies that immunoprecipitate the ligand/channel complex can thus be titrated. Analysis of 31 LEMS sera revealed the presence of anti-N type channel antibodies in 58% and anti-P/Q type channel antibodies in 74% of patients with titres ranging from 90 to 2950 pM. Only 5 patients were seronegative in both tests, thus a combination of the two assays reliably detected autoantibodies in 26/31 (84%) patients.
Collapse
Affiliation(s)
- N Martin-Moutot
- UMR 641 INSERM / Université de la Méditerranée, IFR Jean Roche, Faculté de Médecine Secteur Nord, Marseille, France.
| | | | | |
Collapse
|
44
|
Brunette MG, Leclerc M, Couchourel D, Mailloux J, Bourgeois Y. Characterization of three types of calcium channel in the luminal membrane of the distal nephron. Can J Physiol Pharmacol 2004; 82:30-7. [PMID: 15052303 DOI: 10.1139/y03-127] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We previously reported a dual kinetics of Ca2+transport by the distal tubule luminal membrane of the kidney, suggesting the presence of several types of channels. To better characterize these channels, we examined the effects of specific inhibitors (i.e., diltiazem, an L-type channel; ω-conotoxin MVIIC, a P/Q-type channel; and mibefradil, a T-type channel antagonist) on 0.1 and 0.5 mM Ca2+uptake by rabbit nephron luminal membranes. None of these inhibitors influenced Ca2+uptake by the proximal tubule membranes. In contrast, in the absence of sodium (Na+), the three channel antagonists decreased Ca2+transport by the distal membranes, and their action depended on the substrate concentrations: 50 µM diltiazem decreased 0.1 mM Ca2+uptake from 0.65 ± 0.07 to 0.48 ± 0.06 pmol·µg–1·10 s–1(P < 0.05) without influencing 0.5 mM Ca2+transport, whereas 100 nM ω-conotoxin MVIIC decreased 0.5 mM Ca2+uptake from 1.02 ± 0.05 to 0.90 ± 0.05 pmol·µg–1·10 s–1(P < 0.02) and 1 µM mibefradil decreased it from 1.13 ± 0.09 to 0.94 ± 0.09 pmol·µg–1·10 s–1(P < 0.05); the latter two inhibitors left 0.1 mM Ca2+transport unchanged. Diltiazem decreased the Vmaxof the high-affinity channels, whereas ω-conotoxin MVIIC and mibefradil influenced exclusively the Vmaxof the low-affinity channels. These results not only confirm that the distal luminal membrane is the site of Ca2+channels, but they suggest that these channels belong to the L, P/Q, and T types.Key words: renal calcium transport, calcium channels, diltiazem, mibefradil, ω-conotoxin.
Collapse
Affiliation(s)
- M G Brunette
- Maisonneuve-Rosemont Hospital, 5415 Boulevard l'Assomption, Montreal, Quebec H1T 2M4, Canada
| | | | | | | | | |
Collapse
|
45
|
Vincent A. Antibody-mediated disorders of neuromuscular transmission. SUPPLEMENTS TO CLINICAL NEUROPHYSIOLOGY 2004; 57:147-58. [PMID: 16106615 DOI: 10.1016/s1567-424x(09)70352-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Angela Vincent
- Neurosciences Group, Department of Clinical Neurology, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS, UK.
| |
Collapse
|
46
|
Iwasa K, Pinto A, Vincent A, Lang B. LEMS IgG binds to extracellular determinants on N-type voltage-gated calcium channels, but does not reduce VGCC expression. Ann N Y Acad Sci 2003; 998:196-9. [PMID: 14592875 DOI: 10.1196/annals.1254.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Kazuo Iwasa
- Department of Neurology, Kanazawa University School of Medicine, Takara-machi, Kanazawa 920-8641, Japan.
| | | | | | | |
Collapse
|
47
|
Lang B, Pinto A, Giovannini F, Newsom-Davis J, Vincent A. Pathogenic Autoantibodies in the Lambert-Eaton Myasthenic Syndrome. Ann N Y Acad Sci 2003; 998:187-95. [PMID: 14592874 DOI: 10.1196/annals.1254.019] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disorder of neuromuscular transmission in which antibodies are directed against voltage-gated calcium channels (VGCCs). We studied the action of LEMS immunoglobulin G (IgG) on cloned human VGCCs stably transfected into human embryonic kidney cells (HEK293). All LEMS IgGs tested bound to the surface of the P/Q-type VGCC cell line and caused a significant reduction in whole-cell calcium currents in these cells. By contrast, only 2 out of 6 IgGs bound extracellularly to the N-type VGCC cell line, and none of the LEMS IgGs tested was able to reduce whole-cell calcium currents in these cells. We used this apparent specificity of LEMS IgG for the P/Q-type VGCC to investigate the action of these IgGs on model systems where a number of different VGCC populations exist in equilibrium. LEMS IgG caused a significant downregulation in the omega-agatoxin IVA-sensitive P/Q-type VGCCs of cultured rat cerebellar neurons, but this was accompanied by a concomitant rise in the "resistant" R-type VGCCs. By using the passive transfer model of LEMS, similar results were observed at the mouse neuromuscular junction, where a significant reduction in P/Q-type VGCCs was paralleled by an increase in L- and R-type VGCCs. These results demonstrate an unexpected plasticity in the expression of VGCCs in mammalian neurons and may represent a mechanism by which the pathogenic effects of LEMS IgG are reduced.
Collapse
Affiliation(s)
- Bethan Lang
- Neurosciences Group and Department of Clinical Neurology, Oxford University, Oxford, United Kingdom.
| | | | | | | | | |
Collapse
|
48
|
Newsom-Davis J, Buckley C, Clover L, Hart I, Maddison P, Tüzüm E, Vincent A. Autoimmune Disorders of Neuronal Potassium Channels. Ann N Y Acad Sci 2003; 998:202-10. [PMID: 14592877 DOI: 10.1196/annals.1254.022] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Antibodies to voltage-gated potassium channels (VGKCs) appear likely to be the effector mechanisms in many patients with acquired peripheral nerve hyperexcitability (APNH) syndromes, a group of disorders that include neuromyotonia, cramp-fasciculation syndrome, and Isaacs' syndrome. They may contribute to the associated autonomic changes. Through a central action, they may also be the effector mechanism in those with Morvan's syndrome and in some patients with limbic encephalitis. Evidence supporting this hypothesis includes the increased association of APNH with autoimmune diseases (in particular, myasthenia gravis and thymoma), the response to plasmapheresis, passive transfer of APNH to experimental animals by patients' plasma or immunoglobulins, the action of their serum on VGKC currents studied in vitro, and the presence in many patients of IgG antibodies to VGKCs.
Collapse
Affiliation(s)
- John Newsom-Davis
- Weatherall Institute of Molecular Medicine and Department of Clinical Neurology, University of Oxford, Oxford, United Kingdom.
| | | | | | | | | | | | | |
Collapse
|
49
|
Fukuda T, Motomura M, Nakao Y, Shiraishi H, Yoshimura T, Iwanaga K, Tsujihata M, Eguchi K. Reduction of P/Q-type calcium channels in the postmortem cerebellum of paraneoplastic cerebellar degeneration with Lambert-Eaton myasthenic syndrome. Ann Neurol 2003; 53:21-8. [PMID: 12509844 DOI: 10.1002/ana.10392] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The aim of this study was to clarify whether autoimmunity against P/Q-type voltage-gated calcium channels (VGCCs) in the cerebellum was associated with the pathogenesis of paraneoplastic cerebellar degeneration (PCD) with Lambert-Eaton myasthenic syndrome (LEMS). We used human autopsy cerebellar tissues from three PCD-LEMS patients and six other disease patients including one with LEMS as the controls. We compared cerebellar P/Q-type VGCC in these patients and controls for the amount and ratio of autoantibody-channel complex using an 125I-omega-conotoxin MVIIC-binding assay with Scatchard analysis, and their distribution using autoradiography. The quantity of cerebellar P/Q-type VGCC measured by Scatchard analysis were reduced in PCD-LEMS patients (63.0 +/- 7.0 fmol/mg, n = 3), compared with the controls (297.8 +/- 38.9 fmol/mg, n = 6). The ratio of autoantibody-VGCC complexes to total P/Q-type VGCCs measured by immunoprecipitation assay were increased in PCD-LEMS patients. We analysed cerebellar specimens by autoradiography using (125)I-omega-conotoxin MVIIC, which specifically binds to P/Q-type VGCCs. In PCD-LEMS cerebellum, the toxin binding sites of P/Q-type VGCCs were markedly reduced compared with controls, especially in the molecular layer, which is the richest area of P/Q-type VGCCs in the normal cerebellum. This suggests that P/Q-type VGCCs of the cerebellar molecular layer is the immunological target in developing PCD-LEMS.
Collapse
Affiliation(s)
- Taku Fukuda
- First Department of Internal Medicine, Nagasaki University School of Medicine, Japan
| | | | | | | | | | | | | | | |
Collapse
|
50
|
|