1
|
Saiz A, Graus F. Neuronal antibodies in nonparaneoplastic autoimmune cerebellar ataxias. Curr Opin Neurol 2024; 37:322-328. [PMID: 38483149 DOI: 10.1097/wco.0000000000001260] [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: 04/30/2024]
Abstract
PURPOSE OF REVIEW To describe relevant advances in nonparaneoplastic autoimmune cerebellar ataxias (ACA) with neuronal antibodies. RECENT FINDINGS Apart from metabotropic glutamate receptor 1(mGluR1) antibodies, in recent years, the number of neuronal antibodies against surface antigens in ACA has increased with the description of glutamate kainate receptor subunit 2 (GluK2) antibodies in young patients with cerebellitis. Around 20% of patients with contactin-associated protein-like 2 (CASPR2) encephalitis also present prominent cerebellar ataxia. However, isolate cerebellar ataxia is unusual (<4%). Outcome in patients with neuronal antibodies against surface antigens remains suboptimal despite the cerebellar ataxia probably is antibody-mediated.Concerning neuronal antibodies against intracellular antigens, up to 25% of patients with glutamic acid decarboxylase (GAD) antibodies present transient episodes of vertigo or diplopia that antedate the development of the ACA. There is in-vitro evidence that septin-5 is partially exposed to the membrane and the antibodies may interfere with septin-5 function. The clinical significance of the remaining antibodies against intracellular antigens remains unclear. SUMMARY The number of antibodies against surface antigens is increasing in ACA, but the response to the immunotherapy remains suboptimal. More studies are needed to clarify the role of most of the antibodies against intracellular antigens described in these patients.
Collapse
Affiliation(s)
- Albert Saiz
- Service of Neurology, Hospital Clinic
- Neuroimmunology Program, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Francesc Graus
- Neuroimmunology Program, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| |
Collapse
|
2
|
Kadish R, Clardy SL. Epidemiology of paraneoplastic neurologic syndromes. HANDBOOK OF CLINICAL NEUROLOGY 2024; 200:57-77. [PMID: 38494297 DOI: 10.1016/b978-0-12-823912-4.00011-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Paraneoplastic neurologic syndromes (PNS), initially depicted as seemingly cryptic remote manifestations of malignancy, were first described clinically in the early 20th century, with pathophysiologic correlates becoming better elucidated in the latter half of the century. There remain many questions not only about the pathophysiology but also regarding the epidemiology of these conditions. The continuous discovery of novel autoantigens and related neurologic disease has broadened the association in classical PNS to include conditions such as paraneoplastic cerebellar degeneration. It has also brought into focus several other neurologic syndromes with a putative neoplastic association. These conditions are overall rare, making it difficult to capture large numbers of patients to study, and raising the question of whether incidence is increasing over time or improved identification is driving the increased numbers of cases. With the rise and increasing use of immunotherapy for cancer treatment, the incidence of these conditions is additionally expected to rise and may present with various clinical symptoms. As we enter an era of clinical trial intervention in these conditions, much work is needed to capture more granular data on population groups defined by socioeconomic characteristics such as age, ethnicity, economic resources, and gender to optimize care and clinical trial planning.
Collapse
Affiliation(s)
- Robert Kadish
- Department of Neurology, University of Utah, Salt Lake City, UT, United States
| | - Stacey L Clardy
- Department of Neurology, University of Utah, Salt Lake City, UT, United States; George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, UT, United States.
| |
Collapse
|
3
|
Chetwynd SA, Andrews S, Inglesfield S, Delon C, Ktistakis NT, Welch HCE. Functions and mechanisms of the GPCR adaptor protein Norbin. Biochem Soc Trans 2023; 51:1545-1558. [PMID: 37503670 PMCID: PMC10586782 DOI: 10.1042/bst20221349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 06/27/2023] [Accepted: 07/07/2023] [Indexed: 07/29/2023]
Abstract
Norbin (Neurochondrin, NCDN) is a highly conserved 79 kDa adaptor protein that was first identified more than a quarter of a century ago as a gene up-regulated in rat hippocampus upon induction of long-term potentiation. Most research has focussed on the role of Norbin in the nervous system, where the protein is highly expressed. Norbin regulates neuronal morphology and synaptic plasticity, and is essential for normal brain development and homeostasis. Dysregulation of Norbin is linked to a variety of neurological conditions. Recently, Norbin was shown to be expressed in myeloid cells as well as neurons. Myeloid-cell specific deletion revealed an important role of Norbin as a suppressor of neutrophil-derived innate immunity. Norbin limits the ability of neutrophils to clear bacterial infections by curbing the responsiveness of these cells to inflammatory and infectious stimuli. Mechanistically, Norbin regulates cell responses through binding to its interactors, in particular to a wide range of G protein-coupled receptors (GPCRs). Norbin association with GPCRs controls GPCR trafficking and signalling. Other important Norbin interactors are the Rac guanine-nucleotide exchange factor P-Rex1 and protein kinase A. Downstream signalling pathways regulated by Norbin include ERK, Ca2+ and the small GTPase Rac. Here, we review the current understanding of Norbin structure, expression and its roles in health and disease. We also explore Norbin signalling through its interactors, with a particular focus on GPCR trafficking and signalling. Finally, we discuss avenues that could be pursued in the future to increase our understanding of Norbin biology.
Collapse
Affiliation(s)
| | - Simon Andrews
- Bioinformatics Facility, Babraham Institute, Cambridge, U.K
| | | | | | | | | |
Collapse
|
4
|
Schwarzwald A, Salmen A, León Betancourt AX, Diem L, Hammer H, Radojewski P, Rebsamen M, Kamber N, Chan A, Hoepner R, Friedli C. Anti-neurochondrin antibody as a biomarker in primary autoimmune cerebellar ataxia-a case report and review of the literature. Eur J Neurol 2023; 30:1135-1147. [PMID: 36437687 DOI: 10.1111/ene.15648] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/22/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND PURPOSE Neuronal autoantibodies can support the diagnosis of primary autoimmune cerebellar ataxia (PACA). Knowledge of PACA is still sparce. This article aims to highlight the relevance of anti-neurochondrin antibodies and possible therapeutical consequences in people with PACA. METHODS This is a case presentation and literature review of PACA associated with anti-neurochondrin antibodies. RESULTS A 33-year-old man noticed reduced control of the right leg in May 2020. During his first clinic appointment at our institution in September 2021, he complained about gait imbalance, fine motor disorders, tremor, intermittent diplopia and slurred speech. He presented a pancerebellar syndrome with stance, gait and limb ataxia, scanning speech and oculomotor dysfunction. Within 3 months the symptoms progressed. An initial cerebral magnetic resonance imaging, June 2020, was normal, but follow-up imaging in October 2021 and July 2022 revealed marked cerebellar atrophy (29% volume loss). Cerebrospinal fluid analysis showed lymphocytic pleocytosis of 11 x 103 /L (normal range 0-4) and oligoclonal bands type II. Anti-neurochondrin antibodies (immunoglobulin G) were detected in serum (1:10,000) and cerebrospinal fluid (1:320, by cell-based indirect immunofluorescence assay and immunoblot, analysed by the EUROIMMUN laboratory). After ruling out alternative causes and neoplasia, diagnosis of PACA was given and immunotherapy (steroids and cyclophosphamide) was started in January 2022. In March 2022 a stabilization of disease was observed. CONCLUSION Cerebellar ataxia associated with anti-neurochondrin antibodies has only been described in 19 cases; however, the number of unrecognized PACAs may be higher. As anti-neurochondrin antibodies target an intracellular antigen and exhibit a mainly cytotoxic T-cell-mediated pathogenesis, important therapeutic implications may result. Because of the severe and rapid clinical progression, aggressive immunotherapy was warranted. This case highlights the need for rapid diagnosis and therapy in PACA, as stabilization and even improvement of symptoms are attainable.
Collapse
Affiliation(s)
- Anina Schwarzwald
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
- Clinic Bethesda, Neurorehabilitation, Parkinson Centre, Epileptology, Tschugg, Switzerland
| | - Anke Salmen
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | | | - Lara Diem
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Helly Hammer
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Piotr Radojewski
- Support Center for Advanced Neuroimaging (SCAN), University Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Michael Rebsamen
- Support Center for Advanced Neuroimaging (SCAN), University Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Nicole Kamber
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Andrew Chan
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Robert Hoepner
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Christoph Friedli
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| |
Collapse
|
5
|
Rare Etiologies in Immune-Mediated Cerebellar Ataxias: Diagnostic Challenges. Brain Sci 2022; 12:brainsci12091165. [PMID: 36138901 PMCID: PMC9496914 DOI: 10.3390/brainsci12091165] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/06/2022] [Accepted: 08/26/2022] [Indexed: 12/03/2022] Open
Abstract
The cerebellum is particularly enriched in antigens and represents a vulnerable target to immune attacks. Immune-mediated cerebellar ataxias (IMCAs) have diverse etiologies, such as gluten ataxia (GA), post-infectious cerebellitis (PIC), Miller Fisher syndrome (MFS), paraneoplastic cerebellar degeneration (PCD), opsoclonus myoclonus syndrome (OMS), and anti-GAD ataxia. Apart from these well-established entities, cerebellar ataxia (CA) occurs also in association with autoimmunity against ion channels and related proteins, synaptic adhesion/organizing proteins, transmitter receptors, glial cells, as well as the brainstem antigens. Most of these conditions manifest diverse neurological clinical features, with CAs being one of the main clinical phenotypes. The term primary autoimmune cerebellar ataxia (PACA) refers to ataxic conditions suspected to be autoimmune even in the absence of specific well-characterized pathogenic antibody markers. We review advances in the field of IMCAs and propose a clinical approach for the understanding and diagnosis of IMCAs, focusing on rare etiologies which are likely underdiagnosed. The frontiers of PACA are discussed. The identification of rare immune ataxias is of importance since they are potentially treatable and may lead to a severe clinical syndrome in absence of early therapy.
Collapse
|