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Liu S, Hong Y, Wang BR, Wei ZQ, Zhao HD, Jiang T, Zhang YD, Shi JQ. The presence and clinical significance of autoantibodies in amyotrophic lateral sclerosis: a narrative review. Neurol Sci 2024:10.1007/s10072-024-07581-x. [PMID: 38733435 DOI: 10.1007/s10072-024-07581-x] [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: 02/01/2024] [Accepted: 05/03/2024] [Indexed: 05/13/2024]
Abstract
Amyotrophic lateral sclerosis (ALS) is a debilitating and rapidly fatal neurodegenerative disease, which is characterized by the selective loss of the upper and lower motor neurons. The pathogenesis of ALS remains to be elucidated and has been connected to genetic, environmental and immune conditions. Evidence from clinical and experimental studies has suggested that the immune system played an important role in ALS pathophysiology. Autoantibodies are essential components of the immune system. Several autoantibodies directed at antigens associated with ALS pathogenesis have been identified in the serum and/or cerebrospinal fluid of ALS patients. The aim of this review is to summarize the presence and clinical significance of autoantibodies in ALS.
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Affiliation(s)
- Shen Liu
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, 210006, PR China
| | - Ye Hong
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, 210006, PR China
| | - Bian-Rong Wang
- Department of Neurology, Geriatric Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, 210006, PR China
| | - Zi-Qiao Wei
- The Second Clinical Medical School of Nanjing Medical University, Nanjing, Jiangsu Province, 211166, PR China
| | - Hong-Dong Zhao
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, 210006, PR China
| | - Teng Jiang
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, 210006, PR China
| | - Ying-Dong Zhang
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, 210006, PR China
| | - Jian-Quan Shi
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, 210006, PR China.
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Letter to the Editor: Autoimmune pathogenic mechanisms in Amyotrophic Lateral Sclerosis. Autoimmun Rev 2018. [PMID: 29526629 DOI: 10.1016/j.autrev.2018.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Maglemose R, Hedegaard A, Lehnhoff J, Dimintiyanova KP, Moldovan M, Grøndahl L, Meehan CF. Potassium channel abnormalities are consistent with early axon degeneration of motor axons in the G127X SOD1 mouse model of amyotrophic lateral sclerosis. Exp Neurol 2017; 292:154-167. [PMID: 28322742 DOI: 10.1016/j.expneurol.2017.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 02/21/2017] [Accepted: 03/14/2017] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative disease, which selectively affects upper and lower motoneurones. The underlying pathophysiology of the disease is complex but electrophysiological studies of peripheral nerves in ALS patients as well as human autopsy studies indicate that a potassium channel dysfunction/loss is present early in the symptomatic phase. It remains unclear to what extent potassium channel abnormalities reflect a specific pathogenic mechanism in ALS. The aim of this study was therefore to investigate the temporal changes in the expression and/or function of potassium channels in motoneurones in the adult G127X SOD1 mouse model of ALS, a model which has a very long presymptomatic phase. Evidence from animal models indicates that the early progressive motoneurone dysfunction and degeneration can be largely compensated by motor unit remodeling, delaying the clinical symptom onset. Experiments were therefore performed both before and after symptom onset. Immunohistochemistry of motor axons in the ventral roots of G127X SOD1 mice, was used to investigate juxta-paranodal Kv1.2 potassium channels along with nodal Nav1.6 and the paranodal scaffolding protein Caspr. This allowed an investigation of changes in the distribution of Kv1.2 relative to the general structure of the nodal-paranodal-juxta-paranodal complex. This revealed that the motor axons in the ventral roots of presymptomatic G127X SOD1 mice, already show a disruption in juxta-paranodal Kv1.2 potassium channels. The axonal Kv1.2 disruption was preceded by abnormalities in the distribution of the paranodal scaffolding protein Caspr with the nodal arrangement of Nav1.6 appearing relatively preserved even in symptomatic mice. These changes were accompanied by axon swelling and a slowing of conduction in the peripheral motor axons in symptomatic mice. In vivo electrophysiological intracellular recordings of individual spinal motoneurones revealed that central potassium channel function was preserved or even enhanced with higher amplitude and longer duration after-hyperpolarisations in the G127X SOD1 mice. Our data suggest that the potassium channel abnormalities observed in presymptomatic G127X, rather than representing a specific pathophysiological mechanism targeting potassium channels, most likely reflect early axonal degenerative changes, consistent with the "dying-back" phenomenon observed in other ALS models.
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Affiliation(s)
- Rikke Maglemose
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Anne Hedegaard
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Janna Lehnhoff
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | | | - Mihai Moldovan
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Lillian Grøndahl
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Claire Francesca Meehan
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
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Copy Number Variations in Amyotrophic Lateral Sclerosis: Piecing the Mosaic Tiles Together through a Systems Biology Approach. Mol Neurobiol 2017; 55:1299-1322. [PMID: 28120152 PMCID: PMC5820374 DOI: 10.1007/s12035-017-0393-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 01/06/2017] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating and still untreatable motor neuron disease. Despite the molecular mechanisms underlying ALS pathogenesis that are still far from being understood, several studies have suggested the importance of a genetic contribution in both familial and sporadic forms of the disease. In addition to single-nucleotide polymorphisms (SNPs), which account for only a limited number of ALS cases, a consistent number of common and rare copy number variations (CNVs) have been associated to ALS. Most of the CNV-based association studies use a traditional candidate-gene approach that is inadequate for uncovering the genetic architectures of complex traits like ALS. The emergent paradigm of “systems biology” may offer a new perspective to better interpret the wide spectrum of CNVs in ALS, enabling the characterization of the complex network of gene products underlying ALS pathogenesis. In this review, we will explore the landscape of CNVs in ALS, putting specific emphasis on the functional impact of common CNV regions and genes consistently associated with increased risk of developing disease. In addition, we will discuss the potential contribution of multiple rare CNVs in ALS pathogenesis, focusing our attention on the complex mechanisms by which these proteins might impact, individually or in combination, the genetic susceptibility of ALS. The comprehensive detection and functional characterization of common and rare candidate risk CNVs in ALS susceptibility may bring new pieces into the intricate mosaic of ALS pathogenesis, providing interesting and important implications for a more precise molecular biomarker-assisted diagnosis and more effective and personalized treatments.
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Godani M, Zoccarato M, Beronio A, Zuliani L, Benedetti L, Giometto B, Del Sette M, Raggio E, Baldi R, Vincent A. Voltage-Gated Potassium Channel Antibodies in Slow-Progression Motor Neuron Disease. NEURODEGENER DIS 2016; 17:59-62. [PMID: 27710962 DOI: 10.1159/000447715] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 06/17/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The spectrum of autoimmune neurological diseases associated with voltage-gated potassium channel (VGKC)-complex antibodies (Abs) ranges from peripheral nerve disorders to limbic encephalitis. Recently, low titers of VGKC-complex Abs have also been reported in neurodegenerative disorders, but their clinical relevance is unknown. OBJECTIVE The aim of the study was to explore the prevalence of VGKC-complex Abs in slow-progression motor neuron disease (MND). METHODS We compared 11 patients affected by slow-progression MND with 9 patients presenting typical progression illness. Sera were tested for VGKC-complex Abs by radioimmunoassay. The distribution of VGKC-complex Abs was analyzed with the Mann-Whitney U test. RESULTS The statistical analysis showed a significant difference between the mean values in the study and control groups. A case with long-survival MND harboring VGKC-complex Abs and treated with intravenous immunoglobulins is described. CONCLUSION Although VGKC-complex Abs are not likely to be pathogenic, these results could reflect the coexistence of an immunological activation in patients with slow disease progression.
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Iwai Y, Shibuya K, Misawa S, Sekiguchi Y, Watanabe K, Amino H, Kuwabara S. Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis. PLoS One 2016; 11:e0158596. [PMID: 27383069 PMCID: PMC4934877 DOI: 10.1371/journal.pone.0158596] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 06/18/2016] [Indexed: 12/20/2022] Open
Abstract
Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS), suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP) amplitude (index of motor neuronal loss) and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44), ALS patients (n = 140) had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p < 0.05), greater threshold changes in depolarizing threshold electrotonus (p < 0.05) and depolarizing current threshold relationship (i.e. less accommodation; (p < 0.05), greater superexcitability (a measure of fast potassium current; p < 0.05) and reduced late subexcitability (a measure of slow potassium current; p < 0.05), suggesting increased persistent sodium currents and decreased potassium currents. The reduced potassium currents were found even in the patient subgroups with normal CMAP (> 5mV). Regression analyses showed that SDTC (R = -0.22) and depolarizing threshold electrotonus (R = -0.22) increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS.
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Affiliation(s)
- Yuta Iwai
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Kazumoto Shibuya
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Sonoko Misawa
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yukari Sekiguchi
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Keisuke Watanabe
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Hiroshi Amino
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Satoshi Kuwabara
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
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Leis AA, Ross MA, Verheijde JL, Leis JF. Immunoablation and Stem Cell Transplantation in Amyotrophic Lateral Sclerosis: The Ultimate Test for the Autoimmune Pathogenesis Hypothesis. Front Neurol 2016; 7:12. [PMID: 26903945 PMCID: PMC4749695 DOI: 10.3389/fneur.2016.00012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Accepted: 01/22/2016] [Indexed: 12/12/2022] Open
Affiliation(s)
- A Arturo Leis
- Department of Neurology, Mayo Clinic Arizona, Scottsdale, AZ, USA; Center for Neuroscience and Neurological Recovery, Methodist Rehabilitation Center, Jackson, MS, USA
| | - Mark A Ross
- Department of Neurology, Mayo Clinic Arizona , Scottsdale, AZ , USA
| | - Joseph L Verheijde
- Department of Physical Medicine and Rehabilitation, Mayo Clinic Arizona , Scottsdale, AZ , USA
| | - Jose F Leis
- Division of Hematology Oncology, Mayo Clinic Arizona , Phoenix, AZ , USA
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Donaldson R, Li J, Li Y. Clinical significance of cation channel antibodies in motor neuron disease. Muscle Nerve 2016; 54:228-31. [DOI: 10.1002/mus.25046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Revised: 01/07/2015] [Accepted: 01/12/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Rachel Donaldson
- Department of Neurology; Cleveland Clinic Foundation; 9500 Euclid Avenue Cleveland Ohio 44195 USA
| | - Jianbo Li
- Department of Quantitative Health Sciences; Learner Research Institute, Cleveland Clinic Foundation; Cleveland Ohio USA
| | - Yuebing Li
- Department of Neurology; Cleveland Clinic Foundation; 9500 Euclid Avenue Cleveland Ohio 44195 USA
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Chhetri SK, Majeed T, Lekwuwa G, Boothman B. Very high titers of voltage-gated potassium channel antibodies in a patient with amyotrophic lateral sclerosis. Muscle Nerve 2014; 51:147. [DOI: 10.1002/mus.24460] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Suresh Kumar Chhetri
- Department of Neurology; Lancashire Teaching Hospitals NHS Foundation Trust; Preston UK
| | - Tahir Majeed
- Department of Neurology; Lancashire Teaching Hospitals NHS Foundation Trust; Preston UK
| | - Godwin Lekwuwa
- Department of Neurophysiology; Royal Preston Hospital, Lancashire Teaching Hospitals NHS Foundation Trust; Preston UK
| | - Bernard Boothman
- Department of Neurology; Lancashire Teaching Hospitals NHS Foundation Trust; Preston UK
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Sato A, Sakai N, Shinbo J, Hashidate H, Igarashi S, Kakita A, Yamazaki M. [An autopsy case of amyotrophic lateral sclerosis with prominent muscle cramps, fasciculation, and high titer of anti-voltage gated potassium channel (VGKC) complex antibody]. Rinsho Shinkeigaku 2014; 54:32-7. [PMID: 24429646 DOI: 10.5692/clinicalneurol.54.32] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The patient was a 55-year-old male who had prominent fasciculation and muscle cramps. Muscle weakness and atrophy of the trunk, respiratory system, and extremities gradually progressed. On the basis of these features, we diagnosed this patient as having amyotrophic lateral sclerosis (ALS), however, the upper motor neuron signs were not significant. Following the detection of the anti-voltage gated potassium channel (VGKC) complex antibody at 907.5 pM (normal < 100 pM) and repetitive discharge in a nerve conduction study, immunotherapy with intravenous immunoglobulin, methylprednisolone (mPSL), double filtration plasmapheresis (DFPP), ciclosporin, and rituximab was introduced. mPSL and DFPP showed only tentative effectiveness for fasciculation and muscle cramps, respectively. Thereafter, muscle weakness progressed. The patient died of type II respiratory failure at the age of 57 years, about 2 years after the onset of the disease. At autopsy, a histopathological diagnosis of ALS with lower-motor-predominant degeneration was made. Characteristic cellular features, including Bunina bodies in the remaining lower motor neurons and phosphorylated TAR DNA-binding protein 43-kDa (pTDP-43)-immunopositive inclusions in both upper and lower motor neuron systems, were evident. At present, an immunological role of the anti-VGKC complex antibody in the development of cramp-fasciculation syndrome has been speculated. In this ALS patient, the antibodies might be associated with pathomechanisms underlying the characteristic symptoms.
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Affiliation(s)
- Aki Sato
- Department of Neurology, Niigata City General Hospital
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Bowerman M, Vincent T, Scamps F, Perrin FE, Camu W, Raoul C. Neuroimmunity dynamics and the development of therapeutic strategies for amyotrophic lateral sclerosis. Front Cell Neurosci 2013; 7:214. [PMID: 24312006 PMCID: PMC3833095 DOI: 10.3389/fncel.2013.00214] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 10/28/2013] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal paralytic disorder characterized by the progressive and selective loss of both upper and lower motoneurons. The neurodegenerative process is accompanied by a sustained inflammation in the brain and spinal cord. The neuron-immune interaction, implicating resident microglia of the central nervous system and blood-derived immune cells, is highly dynamic over the course of the disease. Here, we discuss the timely controlled neuroprotective and neurotoxic cues that are provided by the immune environment of motoneurons and their potential therapeutic applications for ALS.
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Affiliation(s)
- Melissa Bowerman
- The Neuroscience Institute of Montpellier, INM, INSERM UMR1051, Saint Eloi Hospital Montpellier, France
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12
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Autoimmune encephalitis: recent updates and emerging challenges. J Clin Neurosci 2013; 21:722-30. [PMID: 24246947 DOI: 10.1016/j.jocn.2013.07.017] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/03/2013] [Accepted: 07/04/2013] [Indexed: 12/12/2022]
Abstract
The knowledge of immune dysregulation and autoimmunity in neurological disorders has expanded considerably in recent times. Recognition of clinical syndromes, reliable methods of diagnosis, and early targeted immunotherapy can lead to a favourable outcome in acute and subacute neurological disorders that may be associated with significant morbidity and mortality if left untreated. This review focuses on the rapidly expanding field of autoimmune encephalitis. We describe the differences between limbic encephalitis associated with antibodies targeting intracellular antigens, and neuronal surface antibody syndromes (NSAS) where the antigens are primarily receptors or synaptic proteins located on the neuronal cell surface. We chronologically highlight important developments in NSAS by focusing on voltage gated potassium channel complex-associated antibody mediated encephalitis, anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis, and anti-dopamine 2 receptor antibody-associated basal ganglia encephalitis. Contentious issues such as the complexities of using serum antibodies as biomarkers, the initiation of central nervous system autoimmunity, and possible pathogenic mechanisms of these antibodies will be reviewed. The therapeutic challenges that clinicians face such as the timing of therapy and the role of second-line therapy will be discussed, with crucial concepts highlighted in the form of clinical vignettes. Future directions will involve the identification of novel antigens and methods to establish their pathogenicity, as well as evaluation of the most efficacious therapeutic strategies in patients with established NSAS.
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Amyotrophic lateral sclerosis with positive anti-acetylcholine receptor antibodies. Case report and review of the literature. J Clin Neuromuscul Dis 2013; 14:82-5. [PMID: 23172389 DOI: 10.1097/cnd.0b013e31824db163] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Myasthenia gravis is a nerve-muscle junction disease, for which the most specific test is an increase in the anti-acetylcholine receptor antibodies (anti-AChR-Abs) titer. Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease affecting both upper and lower motor neurons. Positive AChR-Ab in patients with pure ALS are exceedingly rare. We report the case of a patient with confirmed ALS and very high levels of AChR-Ab and review the literature on this topic.
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Çoban A, Ulusoy C, Giriş M, Turan S, Türkoğlu R, Tüzün E, İdrisoğlu HA. Serum anti-neuronal antibodies in amyotrophic lateral sclerosis. Int J Neurosci 2013; 123:557-62. [DOI: 10.3109/00207454.2013.782025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Arzu Çoban
- 1Department of Neurology, Istanbul Faculty of Medicine, Istanbul University,
Istanbul, Turkey
| | - Canan Ulusoy
- 2Department of Neuroscience, Institute for Experimental Medical Research (DETAE), Istanbul University,
Istanbul, Turkey
| | - Murat Giriş
- 2Department of Neuroscience, Institute for Experimental Medical Research (DETAE), Istanbul University,
Istanbul, Turkey
| | - Selin Turan
- 2Department of Neuroscience, Institute for Experimental Medical Research (DETAE), Istanbul University,
Istanbul, Turkey
| | - Recai Türkoğlu
- 3Department of Neurology, Haydarpasa Numune Education and Research Hospital,
Istanbul, Turkey
| | - Erdem Tüzün
- 2Department of Neuroscience, Institute for Experimental Medical Research (DETAE), Istanbul University,
Istanbul, Turkey
| | - Halil Atilla İdrisoğlu
- 1Department of Neurology, Istanbul Faculty of Medicine, Istanbul University,
Istanbul, Turkey
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Dimitrov AG, Dimitrova NA. Internodal mechanism of pathological afterdischarges in myelinated axons. Muscle Nerve 2013; 49:47-55. [PMID: 23580322 DOI: 10.1002/mus.23874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2013] [Indexed: 11/07/2022]
Abstract
INTRODUCTION Recent optical recordings of transmembrane potentials in the axons of pyramidal neurons have shown that the internodal action potentials (APs) predicted in our previous studies do exist. These novel processes are not well understood. In this study we aim to clarify electrical phenomena in peripheral myelinated axons (MAs). METHODS We used a multi-cable Hodgkin-Huxley-type model to simulate MAs with potassium channels that were either normal or inhibited along a short region of the internodal membrane. A brief stimulus was applied to the first node. RESULTS We demonstrated peculiarities in the internodal APs induced by a saltatory AP: They existed across internodal membranes, were detectable in periaxonal space but not in intracellular space, propagated continuously, collided near the mid-internodes, and produced internodal sources of afterdischarges. CONCLUSIONS These results highlight the importance of the MA internodal regions as new therapeutic targets for avoiding afterdischarges provoked by reduced axonal fast potassium channel expression.
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Affiliation(s)
- Alexander G Dimitrov
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 105, Sofia, 1113, Bulgaria
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Immunocytochemical localization of TASK-3 channels in rat motor neurons. Cell Mol Neurobiol 2011; 32:309-18. [PMID: 22011781 DOI: 10.1007/s10571-011-9762-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 10/03/2011] [Indexed: 12/12/2022]
Abstract
Motor neurons are large cholinergic neurons located in the brain stem and spinal cord. In recent years, a functional role for TASK channels in cellular excitability and vulnerability to anesthetics of motor neurons has been described. Using a polyclonal monospecific antibody against the tandem pore domain K(+) channel (K2P channel) TWIK-related acid-sensitive K(+) channel (TASK-3), we analyzed the expression of the TASK-3 protein in motor systems of the rat CNS. Immunocytochemical staining showed strong TASK-3 expression in motor neurons of the facial, trigeminal, ambiguus, and hypoglossal nuclei. Oculomotor nuclei (including trochlear and abducens nucleus) were also strongly positive for TASK-3. The parasympathetic Edinger-Westphal nucleus and dorsal vagal nucleus showed significant, but weaker expression compared with somato- and branchiomotoric neurons. In addition, motor neurons in the anterior horn of the spinal cord were also strongly labeled for TASK-3 immunoreactivity. Based on morphological criteria, TASK-3 was found in the somatodendritic compartment of motor neurons. Cellular staining using methyl green and immunofluorescence double-labeling with anti-vesicular acetylcholine transporter (anti-vAChT) indicated ubiquitous TASK-3 expression in motor neurons, whereas in other brain regions TASK-3 showed a widespread but not ubiquitous expression. In situ hybridization using a TASK-3 specific riboprobe verified the expression of TASK-3 in motor neurons at the mRNA level.
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Markedly reduced axonal potassium channel expression in human sporadic amyotrophic lateral sclerosis: an immunohistochemical study. Exp Neurol 2011; 232:149-53. [PMID: 21906595 DOI: 10.1016/j.expneurol.2011.08.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 07/27/2011] [Accepted: 08/18/2011] [Indexed: 12/12/2022]
Abstract
Fasciculations are characteristic features of amyotrophic lateral sclerosis (ALS), suggesting abnormally increased excitability of motor axons. Previous nerve excitability studies have shown reduced axonal potassium currents in ALS patients that may contribute to the hyperexcitability and thereby generation of fasciculations. To clarify changes in axonal ion channel expression in motor axons of ALS, we performed immunohistochemistry of potassium and sodium channels in the C7 and L5 ventral/dorsal roots obtained from five autopsy cases of sporadic ALS. Compared to controls, the immunoreactivity of potassium channels (Kv1.2) was markedly reduced in the ventral roots, but normal in the dorsal roots of all the ALS patients. Nodal sodium channel expression was not significantly different in ALS patients and control subjects. Our results show prominently reduced expression of axonal potassium channels, and provide the neuropathological and biological basis for decreased accommodative potassium currents in motor axons of ALS patients. The axonal hyperexcitability would lead to generation of fasciculations, and possibly enhances motor neuron death in ALS.
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Pamphlett R, Morahan JM, Luquin N, Yu B. Looking for differences in copy number between blood and brain in sporadic amyotrophic lateral sclerosis. Muscle Nerve 2011; 44:492-8. [PMID: 21826678 DOI: 10.1002/mus.22095] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2011] [Indexed: 12/12/2022]
Abstract
INTRODUCTION Most analyses of blood DNA in sporadic neuromuscular disorders have been inconclusive. This may be because some genetic variants occur only in brain tissue. We therefore looked for copy number variants (CNVs) in both blood and brain in patients with sporadic amyotrophic lateral sclerosis (SALS). METHODS Genome-wide CNVs were compared in blood and brain from 32 SALS patients and from 26 normal (control) brains, using Affymetrix 6.0 arrays. RESULTS There were 410 CNVs present in brain but not blood (somatic CNVs) in 94% of the patients (median 8 CNVs per patient). Twenty-four of the somatic CNVs were rare, were not found in control brains, and overlapped with genes. CONCLUSIONS Brain-specific CNVs may be common and appear to be present in a proportion of patients with SALS. The more detailed copy number analysis that is becoming available with massively parallel sequencing may uncover brain-specific CNVs that underlie some cases of SALS.
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Affiliation(s)
- Roger Pamphlett
- The Stacey Motor Neuron Disease Laboratory, Department of Pathology, Neuropathology Division, University of Sydney, Sydney, New South Wales 2006, Australia.
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Vucic S, Cheah BC, Yiannikas C, Vincent A, Kiernan MC. Corticomotoneuronal function and hyperexcitability in acquired neuromyotonia. ACTA ACUST UNITED AC 2010; 133:2727-33. [PMID: 20736187 PMCID: PMC2929332 DOI: 10.1093/brain/awq188] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Acquired neuromyotonia encompasses a group of inflammatory disorders characterized by symptoms reflecting peripheral nerve hyperexcitability, which may be clinically confused in the early stages with amyotrophic lateral sclerosis. Despite a clear peripheral nerve focus, it remains unclear whether the ectopic activity in acquired neuromyotonia receives a central contribution. To clarify whether cortical hyperexcitability contributes to development of clinical features of acquired neuromyotonia, the present study investigated whether threshold tracking transcranial magnetic stimulation could detect cortical hyperexcitability in acquired neuromyotonia, and whether this technique could differentiate acquired neuromyotonia from amyotrophic lateral sclerosis. Cortical excitability studies were undertaken in 18 patients with acquired neuromyotonia and 104 patients with amyotrophic lateral sclerosis, with results compared to 62 normal controls. Short-interval intracortical inhibition in patients with acquired neuromyotonia was significantly different when compared to patients with amyotrophic lateral sclerosis (averaged short interval intracortical inhibition acquired neuromyotonia 11.3 ± 1.9%; amyotrophic lateral sclerosis 2.6 ± 0.9%, P < 0.001). In addition, the motor evoked potential amplitudes (acquired neuromyotonia 21.0 ± 3.1%; amyotrophic lateral sclerosis 38.1 ± 2.2%, P < 0.0001), intracortical facilitation (acquired neuromyotonia −0.9 ± 1.3%; amyotrophic lateral sclerosis −2.3 ± 0.6%, P < 0.0001), resting motor thresholds (acquired neuromyotonia 62.2 ± 1.6%; amyotrophic lateral sclerosis 57.2 ± 0.9%, P < 0.05) and cortical silent period durations (acquired neuromyotonia 212.8 ± 6.9 ms; amyotrophic lateral sclerosis 181.1 ± 4.3 ms, P < 0.0001) were significantly different between patients with acquired neuromyotonia and amyotrophic lateral sclerosis. Threshold tracking transcranial magnetic stimulation established corticomotoneuronal integrity in acquired neuromyotonia, arguing against a contribution of central processes to the development of nerve hyperexcitability in acquired neuromyotonia.
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Affiliation(s)
- Steve Vucic
- Neuroscience Research Australia, Barker Street, Randwick, Sydney, NSW 2031, Australia
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