Yael Eshed-Eisenbach, Peter J. Brophy, Elior Peles
Action potential propagation along myelinated axons depends on the geometry of the myelin unit and the division of the underlying axon to specialized domains. The latter include the nodes of Ranvier (NOR), the paranodal junction (PNJ) flanking the nodes, and the adjacent juxtaparanodal region that is located below the compact myelin of the internode. Each of these domains contains a unique composition of axoglial adhesion molecules (CAMs) and cytoskeletal scaffolding proteins, which together direct the placement of specific ion channels at the nodal and juxtaparanodal axolemma. In the last decade it has become increasingly clear that antibodies to some of these axoglial CAMs cause immune-mediated neuropathies. In the current review we detail the molecular composition of the NOR and adjacent membrane domains, describe the function of different CAM complexes that mediate axon-glia interactions along the myelin unit, and discuss their involvement and the underlying mechanisms taking place in peripheral nerve pathologies. This growing group of pathologies represent a new type of neuropathies termed “nodopathies” or “paranodopathies” that are characterized by unique clinical and molecular features which together reflect the mechanisms underlying the molecular assembly and maintenance of this specialized membrane domain.
{"title":"Nodes of Ranvier in health and disease","authors":"Yael Eshed-Eisenbach, Peter J. Brophy, Elior Peles","doi":"10.1111/jns.12568","DOIUrl":"10.1111/jns.12568","url":null,"abstract":"<p>Action potential propagation along myelinated axons depends on the geometry of the myelin unit and the division of the underlying axon to specialized domains. The latter include the nodes of Ranvier (NOR), the paranodal junction (PNJ) flanking the nodes, and the adjacent juxtaparanodal region that is located below the compact myelin of the internode. Each of these domains contains a unique composition of axoglial adhesion molecules (CAMs) and cytoskeletal scaffolding proteins, which together direct the placement of specific ion channels at the nodal and juxtaparanodal axolemma. In the last decade it has become increasingly clear that antibodies to some of these axoglial CAMs cause immune-mediated neuropathies. In the current review we detail the molecular composition of the NOR and adjacent membrane domains, describe the function of different CAM complexes that mediate axon-glia interactions along the myelin unit, and discuss their involvement and the underlying mechanisms taking place in peripheral nerve pathologies. This growing group of pathologies represent a new type of neuropathies termed “nodopathies” or “paranodopathies” that are characterized by unique clinical and molecular features which together reflect the mechanisms underlying the molecular assembly and maintenance of this specialized membrane domain.</p>","PeriodicalId":17451,"journal":{"name":"Journal of the Peripheral Nervous System","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jns.12568","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9834540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The nodes of Ranvier (NoR) are essential domains for nerve conduction and their disruption plays a key role in the pathophysiology of immune-mediated neuropathies. Our understanding of the specialized nodal regions and the immune mechanisms that affect them is growing and has led to the update of peripheral neuropathy classification to include the autoimmune nodopathies, defined by the site of the autoimmune attack. Autoantibodies directed against molecules of the nodal region (as neurofascin-140/186, neurofascin-155, contactin-1, contactin-associated protein 1, contactin-associated protein 2, gangliosides, LGI4, or myelin-associated glycoprotein), macrophage-induced paranodal demyelination, and phenotypic changes of the nodal domains of Schwann cells have been identified as key mechanisms in the pathogenesis of the autoimmune neuropathies. This review explores the current knowledge of the autoimmune vulnerability of the NoR, including the underlying mechanisms leading to dysfunction in the diverse autoimmune disorders.
{"title":"The autoimmune vulnerability of the node of Ranvier","authors":"Luis Querol, Emilien Delmont, Cinta Lleixà","doi":"10.1111/jns.12570","DOIUrl":"10.1111/jns.12570","url":null,"abstract":"<p>The nodes of Ranvier (NoR) are essential domains for nerve conduction and their disruption plays a key role in the pathophysiology of immune-mediated neuropathies. Our understanding of the specialized nodal regions and the immune mechanisms that affect them is growing and has led to the update of peripheral neuropathy classification to include the autoimmune nodopathies, defined by the site of the autoimmune attack. Autoantibodies directed against molecules of the nodal region (as neurofascin-140/186, neurofascin-155, contactin-1, contactin-associated protein 1, contactin-associated protein 2, gangliosides, LGI4, or myelin-associated glycoprotein), macrophage-induced paranodal demyelination, and phenotypic changes of the nodal domains of Schwann cells have been identified as key mechanisms in the pathogenesis of the autoimmune neuropathies. This review explores the current knowledge of the autoimmune vulnerability of the NoR, including the underlying mechanisms leading to dysfunction in the diverse autoimmune disorders.</p>","PeriodicalId":17451,"journal":{"name":"Journal of the Peripheral Nervous System","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9834545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Autoimmune neuropathies are classified, on the basis of pathophysiology, as demyelinating or axonal. The term nodo-paranodopathy, introduced in 2013 to better categorize the neuropathies with antiganglioside antibodies and later expanded to include neuropathies with antibodies to nodal and paranodal axoglial complexes, characterizes disorders in which the nodal region is critical in the pathogenesis. These neuropathies, although presenting electrophysiologic demyelinating features do not show pathologic evidence of segmental demyelination, or, although being classified as axonal, can show reversible nerve conduction failure and rapid recovery contrary with the communal concept of an axonal neuropathy.
Methods
In this personal view is reported, with a splitting approach, an update on autoimmune nodo-paranodopathies, classified according to the domains of peripheral nerve fiber, the target antigens and the antibody class and subclass involved. The clinical features, the electrophysiologic findings, the results of the immunopathological and ultrastructural studies, the pathophysiology and treatment are also described.
Results and Interpretation
The nodo-paranodopathy category integrates the clinical classification of autoimmune neuropathies and expands the traditional dichotomous demyelinating and axonal classification. It helps to a better systematization pointing to the domain and target antigens of the autoimmune process, it resolves conflicting pathologic and electrophysiologic findings, reconciles the contradiction that axonal neuropathies may be rapidly reversible, avoids taxonomical confusion and possible misdiagnoses. Finally this categorization, through the identification of the specific antibody and its prevalent class and subclass, clarifies the pathophysiological mechanisms and addresses to a more targeted therapeutic approach.
{"title":"Autoimmune nodo-paranodopathies 10 years later: Clinical features, pathophysiology and treatment","authors":"Antonino Uncini","doi":"10.1111/jns.12569","DOIUrl":"10.1111/jns.12569","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background and Aims</h3>\u0000 \u0000 <p>Autoimmune neuropathies are classified, on the basis of pathophysiology, as demyelinating or axonal. The term nodo-paranodopathy, introduced in 2013 to better categorize the neuropathies with antiganglioside antibodies and later expanded to include neuropathies with antibodies to nodal and paranodal axoglial complexes, characterizes disorders in which the nodal region is critical in the pathogenesis. These neuropathies, although presenting electrophysiologic demyelinating features do not show pathologic evidence of segmental demyelination, or, although being classified as axonal, can show reversible nerve conduction failure and rapid recovery contrary with the communal concept of an axonal neuropathy.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>In this personal view is reported, with a splitting approach, an update on autoimmune nodo-paranodopathies, classified according to the domains of peripheral nerve fiber, the target antigens and the antibody class and subclass involved. The clinical features, the electrophysiologic findings, the results of the immunopathological and ultrastructural studies, the pathophysiology and treatment are also described.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results and Interpretation</h3>\u0000 \u0000 <p>The nodo-paranodopathy category integrates the clinical classification of autoimmune neuropathies and expands the traditional dichotomous demyelinating and axonal classification. It helps to a better systematization pointing to the domain and target antigens of the autoimmune process, it resolves conflicting pathologic and electrophysiologic findings, reconciles the contradiction that axonal neuropathies may be rapidly reversible, avoids taxonomical confusion and possible misdiagnoses. Finally this categorization, through the identification of the specific antibody and its prevalent class and subclass, clarifies the pathophysiological mechanisms and addresses to a more targeted therapeutic approach.</p>\u0000 </section>\u0000 </div>","PeriodicalId":17451,"journal":{"name":"Journal of the Peripheral Nervous System","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jns.12569","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9834543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Katy Eichinger, Steffen Behrens-Spraggins, Janet E. Sowden, Davide Pareyson, Mary M. Reilly, Steven S. Scherer, Michael E. Shy, David N. Herrmann, the ACT-CMT Study Group
The Accelerate Clinical Trials in
{"title":"Recruiting for an International Rare Disease Clinical Trial Readiness Study during the COVID-19 pandemic: Challenges and solutions","authors":"Katy Eichinger, Steffen Behrens-Spraggins, Janet E. Sowden, Davide Pareyson, Mary M. Reilly, Steven S. Scherer, Michael E. Shy, David N. Herrmann, the ACT-CMT Study Group","doi":"10.1111/jns.12559","DOIUrl":"10.1111/jns.12559","url":null,"abstract":"The Accelerate Clinical Trials in","PeriodicalId":17451,"journal":{"name":"Journal of the Peripheral Nervous System","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2023-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10175111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Several widely used medications, with a relevant efficacy profile, are toxic to the peripheral nervous system and an even larger number of agents are suspected to be neurotoxic. There are concerns about the use of these drugs in patients with Charcot–Marie–Tooth disease (CMT), a hereditary motor and sensory neuropathy. This review provides evidence-based updated recommendations on this clinically relevant topic.
Methods
A systematic review of the available studies/reports written in English was performed from July to September 2022 including in the search string all reported putative neurotoxic drugs.
Results
The results of our systematic review provide evidence-based support for the statement that use of vincristine, and possibly paclitaxel, can occasionally induce an atypical, and more severe, course of drug-related peripheral neurotoxicity in CMT patients. It is therefore reasonable to recommend caution in the use of these compounds in CMT patients. However, no convincing evidence for a similar recommendation could be found for all other drugs.
Interpretation
It is important that patients with CMT are not denied effective treatments that may prolong life expectancy for cancer or improve their health status if affected by non-oncological diseases. Accurate monitoring of peripheral nerve function in CMT patients treated with any neurotoxic agent remains mandatory to detect the earliest signs of neuropathy worsening and atypical clinical courses. Neurologists monitoring CMT patients as part of their normal care package or for natural history studies should keep detailed records of exposures to neurotoxic medications and support reporting of accelerated neuropathy progression if observed.
{"title":"Toxic medications in Charcot–Marie–Tooth patients: A systematic review","authors":"Guido Cavaletti, Katherine Forsey, Paola Alberti","doi":"10.1111/jns.12566","DOIUrl":"10.1111/jns.12566","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background and Aims</h3>\u0000 \u0000 <p>Several widely used medications, with a relevant efficacy profile, are toxic to the peripheral nervous system and an even larger number of agents are suspected to be neurotoxic. There are concerns about the use of these drugs in patients with Charcot–Marie–Tooth disease (CMT), a hereditary motor and sensory neuropathy. This review provides evidence-based updated recommendations on this clinically relevant topic.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A systematic review of the available studies/reports written in English was performed from July to September 2022 including in the search string all reported putative neurotoxic drugs.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The results of our systematic review provide evidence-based support for the statement that use of vincristine, and possibly paclitaxel, can occasionally induce an atypical, and more severe, course of drug-related peripheral neurotoxicity in CMT patients. It is therefore reasonable to recommend caution in the use of these compounds in CMT patients. However, no convincing evidence for a similar recommendation could be found for all other drugs.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Interpretation</h3>\u0000 \u0000 <p>It is important that patients with CMT are not denied effective treatments that may prolong life expectancy for cancer or improve their health status if affected by non-oncological diseases. Accurate monitoring of peripheral nerve function in CMT patients treated with any neurotoxic agent remains mandatory to detect the earliest signs of neuropathy worsening and atypical clinical courses. Neurologists monitoring CMT patients as part of their normal care package or for natural history studies should keep detailed records of exposures to neurotoxic medications and support reporting of accelerated neuropathy progression if observed.</p>\u0000 </section>\u0000 </div>","PeriodicalId":17451,"journal":{"name":"Journal of the Peripheral Nervous System","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jns.12566","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10240436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hiroya Naruse, So Okubo, Atsushi Sudo, Jun Mitsui, Takashi Mikata, Hiroyuki Ishiura, Shinichi Morishita, Shoji Tsuji, Tatsushi Toda
Background and Aims
Pathogenic variants of HSPB1, the gene encoding the small heat shock protein 27, have been reported to cause autosomal dominant distal hereditary motor neuropathy (dHMN) type II and autosomal dominant Charcot–Marie-Tooth (CMT) disease with minimal sensory involvement (CMT2F). This study aimed to describe the clinical features of patients in a family with late-onset dHMN carrying the Pro39Leu variant of HSPB1.
Methods
Whole-exome sequence analysis identified a heterozygous pathogenic variant (Pro39Leu) of HSPB1 in the proband. The presence of the HSPB1 Pro39Leu variant in two affected individuals was confirmed using direct nucleotide sequence analysis.
Results
Both patients exhibited distal muscle weakness with lower extremity predominance and no obvious sensory deficits, leading to a clinical diagnosis of late-onset dHMN. Nerve conduction studies (NCSs) revealed a subclinical complication of sensory disturbance in one of the patients. The clinical and electrophysiological findings of patients with the HSPB1 Pro39Leu variant in this study and previous reports are summarized.
Interpretation
This study suggests that the clinical spectrum of patients carrying HSPB1 Pro39Leu variants, especially the disease onset, might be broader than expected, and HSPB1 variants should be considered in patients diagnosed with late-onset dHMN. Furthermore, patients with dHMN may have concomitant sensory deficits that should be evaluated using NCSs.
{"title":"Clinical features of a family with late-onset distal hereditary motor neuropathy harboring p.Pro39Leu variant of HSPB1","authors":"Hiroya Naruse, So Okubo, Atsushi Sudo, Jun Mitsui, Takashi Mikata, Hiroyuki Ishiura, Shinichi Morishita, Shoji Tsuji, Tatsushi Toda","doi":"10.1111/jns.12567","DOIUrl":"10.1111/jns.12567","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background and Aims</h3>\u0000 \u0000 <p>Pathogenic variants of <i>HSPB1</i>, the gene encoding the small heat shock protein 27, have been reported to cause autosomal dominant distal hereditary motor neuropathy (dHMN) type II and autosomal dominant Charcot–Marie-Tooth (CMT) disease with minimal sensory involvement (CMT2F). This study aimed to describe the clinical features of patients in a family with late-onset dHMN carrying the Pro39Leu variant of <i>HSPB1</i>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Whole-exome sequence analysis identified a heterozygous pathogenic variant (Pro39Leu) of <i>HSPB1</i> in the proband. The presence of the <i>HSPB1</i> Pro39Leu variant in two affected individuals was confirmed using direct nucleotide sequence analysis.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Both patients exhibited distal muscle weakness with lower extremity predominance and no obvious sensory deficits, leading to a clinical diagnosis of late-onset dHMN. Nerve conduction studies (NCSs) revealed a subclinical complication of sensory disturbance in one of the patients. The clinical and electrophysiological findings of patients with the <i>HSPB1</i> Pro39Leu variant in this study and previous reports are summarized.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Interpretation</h3>\u0000 \u0000 <p>This study suggests that the clinical spectrum of patients carrying <i>HSPB1</i> Pro39Leu variants, especially the disease onset, might be broader than expected, and <i>HSPB1</i> variants should be considered in patients diagnosed with late-onset dHMN. Furthermore, patients with dHMN may have concomitant sensory deficits that should be evaluated using NCSs.</p>\u0000 </section>\u0000 </div>","PeriodicalId":17451,"journal":{"name":"Journal of the Peripheral Nervous System","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jns.12567","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10537201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lorenzo Bresciani, Alessandro Salvalaggio, Elisa Vegezzi, Andrea Visentin, Andrea Fortuna, Mariagiulia Anglani, Mario Cacciavillani, Stefano Masciocchi, Silvia Scaranzin, Miryam Carecchio, Andrea Martinuzzi, Matteo Gastaldi, Chiara Briani
Aim
Nodopathies and paranodopathies are autoimmune neuropathies associated with antibodies to nodal–paranodal antigens (neurofascin 140/186 and 155, contactin-1, contactin-associated protein 1 [Caspr1]) characterized by peculiar clinical features, poor response to standard immunotherapies (e.g., intravenous immunoglobulins, IVIg). Improvement after anti-CD20 monoclonal antibody therapy has been reported. Data on Caspr1 antibodies pathogenicity are still preliminary, and longitudinal titers have been poorly described.
Methods
We report on a young woman who developed a disabling neuropathy with antibodies to the Caspr1/contactin-1 complex showing a dramatic improvement after rituximab therapy, mirrored by the decrease of antibody titers.
Results
A 26-year-old woman presented with ataxic-stepping gait, severe motor weakness at four limbs, and low frequency postural tremor. For neurophysiological evidence of demyelinating neuropathy, she was diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy and treated with IVIg without benefit. MRI showed symmetrical hypertrophy and marked signal hyperintensity of brachial and lumbosacral plexi. Cerebrospinal fluid showed 710 mg/dL protein. Despite intravenous methylprednisolone, the patient progressively worsened, and became wheelchair-bound. Antibodies to nodal–paranodal antigens were searched for by ELISA and cell-based assay. Anticontactin/Caspr1 IgG4 antibodies resulted positive. The patient underwent rituximab therapy with slow progressive improvement that mirrored the antibodies titer, measured throughout the disease course.
Conclusions
Our patient had a severe progressive course with early disability and axonal damage, and slow recovery starting only a few months after antibody-depleting therapy. The close correlation between titer, disability, and treatment, supports the pathogenicity of Caspr1 antibodies, and suggest that their longitudinal evaluation might provide a potential biomarker to evaluate treatment response.
{"title":"Caspr1 antibodies autoimmune paranodopathy with severe tetraparesis: Potential relevance of antibody titers in monitoring treatment response","authors":"Lorenzo Bresciani, Alessandro Salvalaggio, Elisa Vegezzi, Andrea Visentin, Andrea Fortuna, Mariagiulia Anglani, Mario Cacciavillani, Stefano Masciocchi, Silvia Scaranzin, Miryam Carecchio, Andrea Martinuzzi, Matteo Gastaldi, Chiara Briani","doi":"10.1111/jns.12565","DOIUrl":"10.1111/jns.12565","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Aim</h3>\u0000 \u0000 <p>Nodopathies and paranodopathies are autoimmune neuropathies associated with antibodies to nodal–paranodal antigens (neurofascin 140/186 and 155, contactin-1, contactin-associated protein 1 [Caspr1]) characterized by peculiar clinical features, poor response to standard immunotherapies (e.g., intravenous immunoglobulins, IVIg). Improvement after anti-CD20 monoclonal antibody therapy has been reported. Data on Caspr1 antibodies pathogenicity are still preliminary, and longitudinal titers have been poorly described.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We report on a young woman who developed a disabling neuropathy with antibodies to the Caspr1/contactin-1 complex showing a dramatic improvement after rituximab therapy, mirrored by the decrease of antibody titers.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>A 26-year-old woman presented with ataxic-stepping gait, severe motor weakness at four limbs, and low frequency postural tremor. For neurophysiological evidence of demyelinating neuropathy, she was diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy and treated with IVIg without benefit. MRI showed symmetrical hypertrophy and marked signal hyperintensity of brachial and lumbosacral plexi. Cerebrospinal fluid showed 710 mg/dL protein. Despite intravenous methylprednisolone, the patient progressively worsened, and became wheelchair-bound. Antibodies to nodal–paranodal antigens were searched for by ELISA and cell-based assay. Anticontactin/Caspr1 IgG4 antibodies resulted positive. The patient underwent rituximab therapy with slow progressive improvement that mirrored the antibodies titer, measured throughout the disease course.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our patient had a severe progressive course with early disability and axonal damage, and slow recovery starting only a few months after antibody-depleting therapy. The close correlation between titer, disability, and treatment, supports the pathogenicity of Caspr1 antibodies, and suggest that their longitudinal evaluation might provide a potential biomarker to evaluate treatment response.</p>\u0000 </section>\u0000 </div>","PeriodicalId":17451,"journal":{"name":"Journal of the Peripheral Nervous System","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2023-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jns.12565","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10554929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Filippos Stavropoulos, Elena Georgiou, Natasa Schiza, Shaughn Bell, Robert H. Baloh, Kleopas A. Kleopa, Irene Sargiannidou
Background and aims
Mitofusin 1 (MFN1) and MFN2 are outer mitochondrial membrane fusogenic proteins regulating mitochondrial network morphology. MFN2 mutations cause Charcot-Marie-Tooth type 2A (CMT2A), an axonal neuropathy characterized by mitochondrial fusion defects, which in the case of a GTPase domain mutant, were rescued following wild-type MFN1/2 (MFN1/2WT) overexpression. In this study, we compared the therapeutic efficiency between MFN1WT and MFN2WT overexpression in correcting mitochondrial defects induced by the novel MFN2K357T mutation located in the highly conserved R3 region.
Methods
Constructs expressing either MFN2K357T, MFN2WT, or MFN1WT under the ubiquitous chicken β-actin hybrid (CBh) promoter were generated. Flag or myc tag was used for their detection. Differentiated SH-SY5Y cells were single transfected with MFN1WT, MFN2WT, or MFN2K357T, as well as double transfected with MFN2K357T/MFN2WT or MFN2K357T/MFN1WT.
Results
SH-SY5Y cells transfected with MFN2K357T exhibited severe perinuclear mitochondrial clustering with axon-like processes devoid of mitochondria. Single transfection with MFN1WT resulted in a more interconnected mitochondrial network than transfection with MFN2WT, accompanied by mitochondrial clusters. Double transfection of MFN2K357T with either MFN1WT or MFN2WT resolved the mutant-induced mitochondrial clusters and led to detectable mitochondria throughout the axon-like processes. MFN1WT showed higher efficacy than MFN2WT in rescuing these defects.
Interpretation
These results further demonstrate the higher potential of MFN1WT over MFN2WT overexpression to rescue CMT2A-induced mitochondrial network abnormalities due to mutations outside the GTPase domain. This higher phenotypic rescue conferred by MFN1WT, possibly due to its higher m
{"title":"Mitofusin 1 overexpression rescues the abnormal mitochondrial dynamics caused by the Mitofusin 2 K357T mutation in vitro","authors":"Filippos Stavropoulos, Elena Georgiou, Natasa Schiza, Shaughn Bell, Robert H. Baloh, Kleopas A. Kleopa, Irene Sargiannidou","doi":"10.1111/jns.12564","DOIUrl":"10.1111/jns.12564","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background and aims</h3>\u0000 \u0000 <p>Mitofusin 1 (MFN1) and MFN2 are outer mitochondrial membrane fusogenic proteins regulating mitochondrial network morphology. <i>MFN2</i> mutations cause Charcot-Marie-Tooth type 2A (CMT2A), an axonal neuropathy characterized by mitochondrial fusion defects, which in the case of a GTPase domain mutant, were rescued following wild-type <i>MFN1/2</i> (<i>MFN1/2</i><sup><i>WT</i></sup>) overexpression. In this study, we compared the therapeutic efficiency between <i>MFN1</i><sup><i>WT</i></sup> and <i>MFN2</i><sup><i>WT</i></sup> overexpression in correcting mitochondrial defects induced by the novel <i>MFN2</i><sup><i>K357T</i></sup> mutation located in the highly conserved R3 region.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Constructs expressing either <i>MFN2</i><sup><i>K357T</i></sup>, <i>MFN2</i><sup><i>WT</i></sup>, or <i>MFN1</i><sup><i>WT</i></sup> under the ubiquitous chicken <i>β</i>-actin hybrid (<i>CBh</i>) promoter were generated. Flag or myc tag was used for their detection. Differentiated SH-SY5Y cells were single transfected with <i>MFN1</i><sup><i>WT</i></sup>, <i>MFN2</i><sup><i>WT</i></sup>, or <i>MFN2</i><sup><i>K357T</i></sup>, as well as double transfected with <i>MFN2</i><sup><i>K357T</i></sup>/<i>MFN2</i><sup><i>WT</i></sup> or <i>MFN2</i><sup><i>K357T</i></sup>/<i>MFN1</i><sup><i>WT</i></sup>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>SH-SY5Y cells transfected with <i>MFN2</i><sup><i>K357T</i></sup> exhibited severe perinuclear mitochondrial clustering with axon-like processes devoid of mitochondria. Single transfection with <i>MFN1</i><sup><i>WT</i></sup> resulted in a more interconnected mitochondrial network than transfection with <i>MFN2</i><sup><i>WT</i></sup>, accompanied by mitochondrial clusters. Double transfection of <i>MFN2</i><sup><i>K357T</i></sup> with either <i>MFN1</i><sup><i>WT</i></sup> or <i>MFN2</i><sup><i>WT</i></sup> resolved the mutant-induced mitochondrial clusters and led to detectable mitochondria throughout the axon-like processes. <i>MFN1</i><sup><i>WT</i></sup> showed higher efficacy than <i>MFN2</i><sup><i>WT</i></sup> in rescuing these defects.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Interpretation</h3>\u0000 \u0000 <p>These results further demonstrate the higher potential of <i>MFN1</i><sup><i>WT</i></sup> over <i>MFN2</i><sup><i>WT</i></sup> overexpression to rescue CMT2A-induced mitochondrial network abnormalities due to mutations outside the GTPase domain. This higher phenotypic rescue conferred by <i>MFN1</i><sup><i>WT</i></sup>, possibly due to its higher m","PeriodicalId":17451,"journal":{"name":"Journal of the Peripheral Nervous System","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jns.12564","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10175098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Peter N. Hansen, Abdullahi A. Mohammed, Lars K. Markvardsen, Henning Andersen, Hatice Tankisi, Søren H. Sindrup, Thomas Krøigård
Background and Aims
Intravenous immunoglobulin (IVIg) has a rapid clinical effect which cannot be explained by remyelination during each treatment cycle in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). This study aimed to investigate axonal membrane properties during the IVIg treatment cycle and their potential correlation with clinically relevant functional measurements.
Methods
Motor nerve excitability testing (NET) of the median nerve was performed before and 4 and 18 days after initiation of an IVIg treatment cycle in 13 treatment-naïve (early) CIDP patients and 24 CIDP patients with long term (late) IVIg treatment, 12 CIDP patients treated with subcutaneous immunoglobulin (SCIg) and 55 healthy controls. Clinical function was measured extensively using the Six Spot Step test, 10-Meter Walk test, 9-Hole Peg test, grip strength, MRC sum score, Overall Neuropathy Limitations Score and Patient Global Impression of Change.
Results
Superexcitability and S2 accommodation decreased significantly in the early treatment group from baseline to day 4 and returned to baseline levels at day 18, suggesting temporary depolarization of the axonal membrane. A similar trend was observed for the late IVIg group. Substantial clinical improvement was observed in both early and late IVIg groups during the entire treatment cycle. No statistically significant correlation was found between clinical and NET changes. No change was found in NET or clinical function in the SCIg group or controls.
Interpretation
NET suggested temporary depolarization of the axonal membrane during IVIg treatment in treatment naïve CIDP patients. The relation to clinical improvement, however, remains speculative.
{"title":"Changes in axonal and clinical function during intravenous and subcutaneous immunoglobulin therapy in chronic inflammatory demyelinating polyneuropathy","authors":"Peter N. Hansen, Abdullahi A. Mohammed, Lars K. Markvardsen, Henning Andersen, Hatice Tankisi, Søren H. Sindrup, Thomas Krøigård","doi":"10.1111/jns.12563","DOIUrl":"10.1111/jns.12563","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background and Aims</h3>\u0000 \u0000 <p>Intravenous immunoglobulin (IVIg) has a rapid clinical effect which cannot be explained by remyelination during each treatment cycle in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). This study aimed to investigate axonal membrane properties during the IVIg treatment cycle and their potential correlation with clinically relevant functional measurements.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Motor nerve excitability testing (NET) of the median nerve was performed before and 4 and 18 days after initiation of an IVIg treatment cycle in 13 treatment-naïve (early) CIDP patients and 24 CIDP patients with long term (late) IVIg treatment, 12 CIDP patients treated with subcutaneous immunoglobulin (SCIg) and 55 healthy controls. Clinical function was measured extensively using the Six Spot Step test, 10-Meter Walk test, 9-Hole Peg test, grip strength, MRC sum score, Overall Neuropathy Limitations Score and Patient Global Impression of Change.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Superexcitability and S2 accommodation decreased significantly in the early treatment group from baseline to day 4 and returned to baseline levels at day 18, suggesting temporary depolarization of the axonal membrane. A similar trend was observed for the late IVIg group. Substantial clinical improvement was observed in both early and late IVIg groups during the entire treatment cycle. No statistically significant correlation was found between clinical and NET changes. No change was found in NET or clinical function in the SCIg group or controls.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Interpretation</h3>\u0000 \u0000 <p>NET suggested temporary depolarization of the axonal membrane during IVIg treatment in treatment naïve CIDP patients. The relation to clinical improvement, however, remains speculative.</p>\u0000 </section>\u0000 </div>","PeriodicalId":17451,"journal":{"name":"Journal of the Peripheral Nervous System","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jns.12563","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10182049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eva Maria Weiß, Miriam Geldermann, Rudolf Martini, Dennis Klein
Background and Aims
The complex cellular and molecular interactions between Schwann cells (SCs) and macrophages during Wallerian degeneration are a prerequisite to allow rapid uptake and degradation of myelin debris and axonal regeneration after peripheral nerve injury. In contrast, in non-injured nerves of Charcot-Marie-Tooth 1 neuropathies, aberrant macrophage activation by SCs carrying myelin gene defects is a disease amplifier that drives nerve damage and subsequent functional decline. Consequently, targeting nerve macrophages might be a translatable treatment strategy to mitigate disease outcome in CMT1 patients. Indeed, in previous approaches, macrophage targeting alleviated the axonopathy and promoted sprouting of damaged fibers. Surprisingly, this was still accompanied by robust myelinopathy in a model for CMT1X, suggesting additional cellular mechanisms of myelin degradation in mutant peripheral nerves. We here investigated the possibility of an increased SC-related myelin autophagy upon macrophage targeting in Cx32def mice.
Methods
Combining ex vivo and in vivo approaches, macrophages were targeted by PLX5622 treatment. SC autophagy was investigated by immunohistochemical and electron microscopical techniques.
Results
We demonstrate a robust upregulation of markers for SC autophagy after injury and in genetically-mediated neuropathy when nerve macrophages are pharmacologically depleted. Corroborating these findings, we provide ultrastructural evidence for increased SC myelin autophagy upon treatment in vivo.
Interpretation
These findings reveal a novel communication and interaction between SCs and macrophages. This identification of alternative pathways of myelin degradation may have important implications for a better understanding of therapeutic mechanisms of pharmacological macrophage targeting in diseased peripheral nerves.
{"title":"Macrophages influence Schwann cell myelin autophagy after nerve injury and in a model of Charcot-Marie-Tooth disease","authors":"Eva Maria Weiß, Miriam Geldermann, Rudolf Martini, Dennis Klein","doi":"10.1111/jns.12561","DOIUrl":"10.1111/jns.12561","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background and Aims</h3>\u0000 \u0000 <p>The complex cellular and molecular interactions between Schwann cells (SCs) and macrophages during Wallerian degeneration are a prerequisite to allow rapid uptake and degradation of myelin debris and axonal regeneration after peripheral nerve injury. In contrast, in non-injured nerves of Charcot-Marie-Tooth 1 neuropathies, aberrant macrophage activation by SCs carrying myelin gene defects is a disease amplifier that drives nerve damage and subsequent functional decline. Consequently, targeting nerve macrophages might be a translatable treatment strategy to mitigate disease outcome in CMT1 patients. Indeed, in previous approaches, macrophage targeting alleviated the axonopathy and promoted sprouting of damaged fibers. Surprisingly, this was still accompanied by robust myelinopathy in a model for CMT1X, suggesting additional cellular mechanisms of myelin degradation in mutant peripheral nerves. We here investigated the possibility of an increased SC-related myelin autophagy upon macrophage targeting in Cx32def mice.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Combining ex vivo and in vivo approaches, macrophages were targeted by PLX5622 treatment. SC autophagy was investigated by immunohistochemical and electron microscopical techniques.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We demonstrate a robust upregulation of markers for SC autophagy after injury and in genetically-mediated neuropathy when nerve macrophages are pharmacologically depleted. Corroborating these findings, we provide ultrastructural evidence for increased SC myelin autophagy upon treatment in vivo.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Interpretation</h3>\u0000 \u0000 <p>These findings reveal a novel communication and interaction between SCs and macrophages. This identification of alternative pathways of myelin degradation may have important implications for a better understanding of therapeutic mechanisms of pharmacological macrophage targeting in diseased peripheral nerves.</p>\u0000 </section>\u0000 </div>","PeriodicalId":17451,"journal":{"name":"Journal of the Peripheral Nervous System","volume":null,"pages":null},"PeriodicalIF":3.8,"publicationDate":"2023-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jns.12561","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10187248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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