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Taub DG, Woolf CJ. Age-dependent small fiber neuropathy: Mechanistic insights from animal models. Exp Neurol 2024; 377:114811. [PMID: 38723859 PMCID: PMC11131160 DOI: 10.1016/j.expneurol.2024.114811] [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: 01/26/2024] [Revised: 04/07/2024] [Accepted: 05/05/2024] [Indexed: 05/28/2024]
Abstract
Small fiber neuropathy (SFN) is a common and debilitating disease in which the terminals of small diameter sensory axons degenerate, producing sensory loss, and in many patients neuropathic pain. While a substantial number of cases are attributable to diabetes, almost 50% are idiopathic. An underappreciated aspect of the disease is its late onset in most patients. Animal models of human genetic mutations that produce SFN also display age-dependent phenotypes suggesting that aging is an important contributor to the risk of development of the disease. In this review we define how particular sensory neurons are affected in SFN and discuss how aging may drive the disease. We also evaluate how animal models of SFN can define disease mechanisms that will provide insight into early risk detection and suggest novel therapeutic interventions.
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Affiliation(s)
- Daniel G Taub
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
| | - Clifford J Woolf
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Department of Neurobiology, Harvard Medical School, Boston, MA, USA
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2
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van Gool R, Far A, Drenthen GS, Jansen JFA, Goijen CP, Backes WH, Linden DEJ, Merkies ISJ, Faber CG, Upadhyay J, Hoeijmakers JGJ. Peripheral Pain Captured Centrally: Altered Brain Morphology on MRI in Small Fiber Neuropathy Patients With and Without an SCN9A Gene Variant. THE JOURNAL OF PAIN 2024; 25:730-741. [PMID: 37921732 DOI: 10.1016/j.jpain.2023.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 09/05/2023] [Accepted: 10/03/2023] [Indexed: 11/04/2023]
Abstract
The current study aims to characterize brain morphology of pain as reported by small fiber neuropathy (SFN) patients with or without a gain-of-function variant involving the SCN9A gene and compare these with findings in healthy controls without pain. The Neuropathic Pain Scale was used in patients with idiopathic SFN (N = 20) and SCN9A-associated SFN (N = 12) to capture pain phenotype. T1-weighted, structural magnetic resonance imaging (MRI) data were collected in patients and healthy controls (N = 21) to 1) compare cortical thickness and subcortical volumes and 2) quantify the association between severity, quality, and duration of pain with morphological properties. SCN9A-associated SFN patients showed significant (P < .017, Bonferroni corrected) higher cortical thickness in sensorimotor regions, compared to idiopathic SFN patients, while lower cortical thickness was found in more functionally diverse regions (eg, posterior cingulate cortex). SFN patient groups combined demonstrated a significant (Spearman's ρ = .44-.55, P = .005-.049) correlation among itch sensations (Neuropathic Pain Scale-7) and thickness of the left precentral gyrus, and midcingulate cortices. Significant associations were found between thalamic volumes and duration of pain (left: ρ = -.37, P = .043; right: ρ = -.40, P = .025). No associations were found between morphological properties and other pain qualities. In conclusion, in SCN9A-associated SFN, profound morphological alterations anchored within the pain matrix are present. The association between itch sensations of pain and sensorimotor and midcingulate structures provides a novel basis for further examining neurobiological underpinnings of itch in SFN. PERSPECTIVE: Cortical thickness and subcortical volume alterations in SFN patients were found in pain hubs, more profound in SCN9A-associated neuropathy, and correlated with itch and durations of pain. These findings contribute to our understanding of the pathophysiological pathways underlying chronic neuropathic pain and symptoms of itch in SFN.
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Affiliation(s)
- Raquel van Gool
- Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Limburg, The Netherlands
| | - Amir Far
- School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Limburg, The Netherlands; Department of Neurology, Maastricht University Medical Center+, Maastricht, Limburg, The Netherlands
| | - Gerhard S Drenthen
- School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Limburg, The Netherlands; Department of Radiology and Nuclear Medicine, Maastricht University Medical Center+, Maastricht, Limburg, The Netherlands
| | - Jacobus F A Jansen
- School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Limburg, The Netherlands; Department of Radiology and Nuclear Medicine, Maastricht University Medical Center+, Maastricht, Limburg, The Netherlands; Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, North Brabant, The Netherlands
| | - Celine P Goijen
- School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Limburg, The Netherlands; Department of Neurology, Maastricht University Medical Center+, Maastricht, Limburg, The Netherlands
| | - Walter H Backes
- School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Limburg, The Netherlands; Department of Radiology and Nuclear Medicine, Maastricht University Medical Center+, Maastricht, Limburg, The Netherlands
| | - David E J Linden
- School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Limburg, The Netherlands; Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Limburg, The Netherlands
| | - Ingemar S J Merkies
- School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Limburg, The Netherlands; Department of Neurology, Maastricht University Medical Center+, Maastricht, Limburg, The Netherlands; Department of Neurology, Curaçao Medical Center, Willemstad, Kingdom of the Netherlands, Curaçao
| | - Catharina G Faber
- School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Limburg, The Netherlands; Department of Neurology, Maastricht University Medical Center+, Maastricht, Limburg, The Netherlands
| | - Jaymin Upadhyay
- Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts
| | - Janneke G J Hoeijmakers
- School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Limburg, The Netherlands; Department of Neurology, Maastricht University Medical Center+, Maastricht, Limburg, The Netherlands
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3
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Neuroimmune crosstalk in the cornea: The role of immune cells in corneal nerve maintenance during homeostasis and inflammation. Prog Retin Eye Res 2022; 91:101105. [PMID: 35868985 DOI: 10.1016/j.preteyeres.2022.101105] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 07/01/2022] [Accepted: 07/04/2022] [Indexed: 12/29/2022]
Abstract
In the cornea, resident immune cells are in close proximity to sensory nerves, consistent with their important roles in the maintenance of nerves in both homeostasis and inflammation. Using in vivo confocal microscopy in humans, and ex vivo immunostaining and fluorescent reporter mice to visualize corneal sensory nerves and immune cells, remarkable progress has been made to advance our understanding of the physical and functional interactions between corneal nerves and immune cells. In this review, we summarize and discuss recent studies relating to corneal immune cells and sensory nerves, and their interactions in health and disease. In particular, we consider how disrupted corneal nerve axons can induce immune cell activity, including in dendritic cells, macrophages and other infiltrating cells, directly and/or indirectly by releasing neuropeptides such as substance P and calcitonin gene-related peptide. We summarize growing evidence that the role of corneal intraepithelial immune cells is likely different in corneal wound healing versus other inflammatory-dominated conditions. The role of different types of macrophages is also discussed, including how stromal macrophages with anti-inflammatory phenotypes communicate with corneal nerves to provide neuroprotection, while macrophages with pro-inflammatory phenotypes, along with other infiltrating cells including neutrophils and CD4+ T cells, can be inhibitory to corneal re-innervation. Finally, this review considers the bidirectional interactions between corneal immune cells and corneal nerves, and how leveraging this interaction could represent a potential therapeutic approach for corneal neuropathy.
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Chen L, Wimalasena NK, Shim J, Han C, Lee SI, Gonzalez-Cano R, Estacion M, Faber CG, Lauria G, Dib-Hajj SD, Woolf CJ, Waxman SG. Two independent mouse lines carrying the Nav1.7 I228M gain-of-function variant display dorsal root ganglion neuron hyperexcitability but a minimal pain phenotype. Pain 2021; 162:1758-1770. [PMID: 33323889 PMCID: PMC8119301 DOI: 10.1097/j.pain.0000000000002171] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 11/23/2020] [Indexed: 01/26/2023]
Abstract
ABSTRACT Small-fiber neuropathy (SFN), characterized by distal unmyelinated or thinly myelinated fiber loss, produces a combination of sensory dysfunction and neuropathic pain. Gain-of-function variants in the sodium channel Nav1.7 that produce dorsal root ganglion (DRG) neuron hyperexcitability are present in 5% to 10% of patients with idiopathic painful SFN. We created 2 independent knock-in mouse lines carrying the Nav1.7 I228M gain-of-function variant, found in idiopathic SFN. Whole-cell patch-clamp and multielectrode array recordings show that Nav1.7 I228M knock-in DRG neurons are hyperexcitable compared with wild-type littermate-control neurons, but despite this, Nav1.7 I228M mice do not display mechanical or thermal hyperalgesia or intraepidermal nerve fiber loss in vivo. Therefore, although these 2 Nav1.7 I228M knock-in mouse lines recapitulate the DRG neuron hyperexcitability associated with gain-of-function mutations in Nav1.7, they do not recapitulate the pain or neuropathy phenotypes seen in patients. We suggest that the relationship between hyperexcitability in sensory neurons and the pain experienced by these patients may be more complex than previously appreciated and highlights the challenges in modelling channelopathy pain disorders in mice.
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Affiliation(s)
- Lubin Chen
- Department of Neurology, Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut
Healthcare System, West Haven, CT 06516, USA
| | - Nivanthika K. Wimalasena
- FM Kirby Neurobiology Center, Boston Children’s
Hospital, Harvard Medical school, Boston, MA 02115, USA
- Department of Neurobiology, Harvard Medical school, Boston,
MA 02115, USA
| | - Jaehoon Shim
- FM Kirby Neurobiology Center, Boston Children’s
Hospital, Harvard Medical school, Boston, MA 02115, USA
- Department of Neurobiology, Harvard Medical school, Boston,
MA 02115, USA
| | - Chongyang Han
- Department of Neurology, Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut
Healthcare System, West Haven, CT 06516, USA
| | - Seong-il Lee
- Department of Neurology, Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut
Healthcare System, West Haven, CT 06516, USA
| | - Rafael Gonzalez-Cano
- FM Kirby Neurobiology Center, Boston Children’s
Hospital, Harvard Medical school, Boston, MA 02115, USA
- Department of Neurobiology, Harvard Medical school, Boston,
MA 02115, USA
| | - Mark Estacion
- Department of Neurology, Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut
Healthcare System, West Haven, CT 06516, USA
| | - Catharina G. Faber
- Department of Neurology, School of Mental Health and
Neuroscience, Maastricht University Medical Center, Maastricht, The
Netherlands
| | - Giuseppe Lauria
- Neuroalgology Unit, IRCCS Foundation, “Carlo
Besta” Neurological Institute, Milan, Italy
- Department of Biomedical and Clinical Sciences
“Luigi Sacco”, University of Milan, Italy
| | - Sulayman D. Dib-Hajj
- Department of Neurology, Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut
Healthcare System, West Haven, CT 06516, USA
| | - Clifford J. Woolf
- FM Kirby Neurobiology Center, Boston Children’s
Hospital, Harvard Medical school, Boston, MA 02115, USA
- Department of Neurobiology, Harvard Medical school, Boston,
MA 02115, USA
| | - Stephen G. Waxman
- Department of Neurology, Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale
University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut
Healthcare System, West Haven, CT 06516, USA
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5
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Gualdani R, Yuan JH, Effraim PR, Di Stefano G, Truini A, Cruccu G, Dib-Hajj SD, Gailly P, Waxman SG. Trigeminal Neuralgia TRPM8 Mutation: Enhanced Activation, Basal [Ca 2+] i and Menthol Response. NEUROLOGY-GENETICS 2021; 7:e550. [PMID: 33977138 PMCID: PMC8105906 DOI: 10.1212/nxg.0000000000000550] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 11/09/2020] [Indexed: 01/20/2023]
Abstract
Objective To assess the functional effects of a variant, c.89 G > A (p.Arg30Gln), in the transient receptor potential melastatin 8 (TRPM8) cold-sensing, nonselective cation channel, which we have previously identified in a patient with familial trigeminal neuralgia. Methods We carried out Ca2+ imaging and whole-cell patch-clamp recording. Results The TRPM8 mutation enhances channel activation, increases basal current amplitude and intracellular [Ca2+] in cells carrying the mutant channel, and enhances the response to menthol. Conclusions We propose that Arg30Gln confers gain-of-function attributes on TRPM8, which contribute to pathogenesis of trigeminal neuralgia in patients carrying this mutation.
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Affiliation(s)
- Roberta Gualdani
- Institute of Neuroscience (R.G., P.G.), Université catholique de Louvain, B-1200 Brussels, Belgium; Department of Neurology (J.-H.Y., S.D.D.-H., S.G.W.), Yale School of Medicine, New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; Department of Anaesthesiology (P.R.E.), Yale School of Medicine New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; and Department of Human Neuroscience (G.D.S., A.T., G.C.), Sapienza University, Rome, Italy
| | - Jun-Hui Yuan
- Institute of Neuroscience (R.G., P.G.), Université catholique de Louvain, B-1200 Brussels, Belgium; Department of Neurology (J.-H.Y., S.D.D.-H., S.G.W.), Yale School of Medicine, New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; Department of Anaesthesiology (P.R.E.), Yale School of Medicine New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; and Department of Human Neuroscience (G.D.S., A.T., G.C.), Sapienza University, Rome, Italy
| | - Philip R Effraim
- Institute of Neuroscience (R.G., P.G.), Université catholique de Louvain, B-1200 Brussels, Belgium; Department of Neurology (J.-H.Y., S.D.D.-H., S.G.W.), Yale School of Medicine, New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; Department of Anaesthesiology (P.R.E.), Yale School of Medicine New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; and Department of Human Neuroscience (G.D.S., A.T., G.C.), Sapienza University, Rome, Italy
| | - Giulia Di Stefano
- Institute of Neuroscience (R.G., P.G.), Université catholique de Louvain, B-1200 Brussels, Belgium; Department of Neurology (J.-H.Y., S.D.D.-H., S.G.W.), Yale School of Medicine, New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; Department of Anaesthesiology (P.R.E.), Yale School of Medicine New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; and Department of Human Neuroscience (G.D.S., A.T., G.C.), Sapienza University, Rome, Italy
| | - Andrea Truini
- Institute of Neuroscience (R.G., P.G.), Université catholique de Louvain, B-1200 Brussels, Belgium; Department of Neurology (J.-H.Y., S.D.D.-H., S.G.W.), Yale School of Medicine, New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; Department of Anaesthesiology (P.R.E.), Yale School of Medicine New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; and Department of Human Neuroscience (G.D.S., A.T., G.C.), Sapienza University, Rome, Italy
| | - Giorgio Cruccu
- Institute of Neuroscience (R.G., P.G.), Université catholique de Louvain, B-1200 Brussels, Belgium; Department of Neurology (J.-H.Y., S.D.D.-H., S.G.W.), Yale School of Medicine, New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; Department of Anaesthesiology (P.R.E.), Yale School of Medicine New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; and Department of Human Neuroscience (G.D.S., A.T., G.C.), Sapienza University, Rome, Italy
| | - Sulayman D Dib-Hajj
- Institute of Neuroscience (R.G., P.G.), Université catholique de Louvain, B-1200 Brussels, Belgium; Department of Neurology (J.-H.Y., S.D.D.-H., S.G.W.), Yale School of Medicine, New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; Department of Anaesthesiology (P.R.E.), Yale School of Medicine New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; and Department of Human Neuroscience (G.D.S., A.T., G.C.), Sapienza University, Rome, Italy
| | - Philippe Gailly
- Institute of Neuroscience (R.G., P.G.), Université catholique de Louvain, B-1200 Brussels, Belgium; Department of Neurology (J.-H.Y., S.D.D.-H., S.G.W.), Yale School of Medicine, New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; Department of Anaesthesiology (P.R.E.), Yale School of Medicine New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; and Department of Human Neuroscience (G.D.S., A.T., G.C.), Sapienza University, Rome, Italy
| | - Stephen G Waxman
- Institute of Neuroscience (R.G., P.G.), Université catholique de Louvain, B-1200 Brussels, Belgium; Department of Neurology (J.-H.Y., S.D.D.-H., S.G.W.), Yale School of Medicine, New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; Department of Anaesthesiology (P.R.E.), Yale School of Medicine New Haven, CT and Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare, West Haven, CT; and Department of Human Neuroscience (G.D.S., A.T., G.C.), Sapienza University, Rome, Italy
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6
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Labau JIR, Estacion M, Tanaka BS, de Greef BTA, Hoeijmakers JGJ, Geerts M, Gerrits MM, Smeets HJM, Faber CG, Merkies ISJ, Lauria G, Dib-Hajj SD, Waxman SG. Differential effect of lacosamide on Nav1.7 variants from responsive and non-responsive patients with small fibre neuropathy. Brain 2020; 143:771-782. [PMID: 32011655 PMCID: PMC7089662 DOI: 10.1093/brain/awaa016] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 11/13/2019] [Accepted: 12/06/2019] [Indexed: 12/20/2022] Open
Abstract
Small fibre neuropathy is a common pain disorder, which in many cases fails to respond to treatment with existing medications. Gain-of-function mutations of voltage-gated sodium channel Nav1.7 underlie dorsal root ganglion neuronal hyperexcitability and pain in a subset of patients with small fibre neuropathy. Recent clinical studies have demonstrated that lacosamide, which blocks sodium channels in a use-dependent manner, attenuates pain in some patients with Nav1.7 mutations; however, only a subgroup of these patients responded to the drug. Here, we used voltage-clamp recordings to evaluate the effects of lacosamide on five Nav1.7 variants from patients who were responsive or non-responsive to treatment. We show that, at the clinically achievable concentration of 30 μM, lacosamide acts as a potent sodium channel inhibitor of Nav1.7 variants carried by responsive patients, via a hyperpolarizing shift of voltage-dependence of both fast and slow inactivation and enhancement of use-dependent inhibition. By contrast, the effects of lacosamide on slow inactivation and use-dependence in Nav1.7 variants from non-responsive patients were less robust. Importantly, we found that lacosamide selectively enhances fast inactivation only in variants from responders. Taken together, these findings begin to unravel biophysical underpinnings that contribute to responsiveness to lacosamide in patients with small fibre neuropathy carrying select Nav1.7 variants.
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Affiliation(s)
- Julie I R Labau
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA.,Department of Neurology, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands.,Department of Genetics and Cell Biology, Clinical Genomics Unit, Maastricht University, Maastricht, The Netherlands
| | - Mark Estacion
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Brian S Tanaka
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Bianca T A de Greef
- Department of Neurology, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands.,Department of Clinical Epidemiology and Medical Technology Assessment (KEMTA), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Janneke G J Hoeijmakers
- Department of Neurology, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Margot Geerts
- Department of Neurology, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Monique M Gerrits
- Department of Clinical Genetics, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Hubert J M Smeets
- Department of Genetics and Cell Biology, Clinical Genomics Unit, Maastricht University, Maastricht, The Netherlands
| | - Catharina G Faber
- Department of Neurology, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Ingemar S J Merkies
- Department of Neurology, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands.,Department of Neurology, St. Elisabeth Hospital, Willemstad, Curaçao
| | - Giuseppe Lauria
- Neuroalgology Unit, IRCCS Foundation, "Carlo Besta" Neurological Institute, Milan, Italy.,Department of Biomedical and Clinical Sciences "Luigi Sacco", University of Milan, Italy
| | - Sulayman D Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA.,Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA.,Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
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7
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Lee SI, Hoeijmakers JGJ, Faber CG, Merkies ISJ, Lauria G, Waxman SG. The small fiber neuropathy NaV1.7 I228M mutation: impaired neurite integrity via bioenergetic and mitotoxic mechanisms, and protection by dexpramipexole. J Neurophysiol 2020; 123:645-657. [DOI: 10.1152/jn.00360.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Gain-of-function variants in voltage-gated sodium channel NaV1.7 that increase firing frequency and spontaneous firing of dorsal root ganglion (DRG) neurons have recently been identified in 5–10% of patients with idiopathic small fiber neuropathy (I-SFN). Our previous in vitro observations suggest that enhanced sodium channel activity can contribute to a decrease in length of peripheral sensory axons. We have hypothesized that sustained sodium influx due to the expression of SFN-associated sodium channel variants may trigger an energetic deficit in neurons that contributes to degeneration and loss of nerve fibers in SFN. Using an ATP FRET biosensor, we now demonstrate reduced steady-state levels of ATP and markedly faster ATP decay in response to membrane depolarization in cultured DRG neurons expressing an SFN-associated variant NaV1.7, I228M, compared with wild-type neurons. We also observed that I228M neurons show a significant reduction in mitochondrial density and size, indicating dysfunctional mitochondria and a reduced bioenergetic capacity. Finally, we report that exposure to dexpramipexole, a drug that improves mitochondrial energy metabolism, increases the neurite length of I228M-expressing neurons. Our data suggest that expression of gain-of-function variants of NaV1.7 can damage mitochondria and compromise cellular capacity for ATP production. The resulting bioenergetic crisis can consequently contribute to loss of axons in SFN. We suggest that, in addition to interventions that reduce ionic disturbance caused by mutant NaV1.7 channels, an alternative therapeutic strategy might target the bioenergetic burden and mitochondrial damage that occur in SFN associated with NaV1.7 gain-of-function mutations. NEW & NOTEWORTHY Sodium channel NaV1.7 mutations that increase dorsal root ganglion (DRG) neuron excitability have been identified in small fiber neuropathy (SFN). We demonstrate reduced steady-state ATP levels, faster depolarization-evoked ATP decay, and reduced mitochondrial density and size in cultured DRG neurons expressing SFN-associated variant NaV1.7 I228M. Dexpramipexole, which improves mitochondrial energy metabolism, has a protective effect. Because gain-of-function NaV1.7 variants can compromise bioenergetics, therapeutic strategies that target bioenergetic burden and mitochondrial damage merit study in SFN.
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Affiliation(s)
- Seong-il Lee
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut
- Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Janneke G. J. Hoeijmakers
- Department of Neurology, School of Mental Health and Neuroscience, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Catharina G. Faber
- Department of Neurology, School of Mental Health and Neuroscience, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Ingemar S. J. Merkies
- Department of Neurology, School of Mental Health and Neuroscience, Maastricht University Medical Center+, Maastricht, The Netherlands
- Department of Neurology, Curaçao Medical Center, Willemstad, Curaçao
| | - Giuseppe Lauria
- Neuroalgology Unit, Foundazione IRCCS Istituto Neurologico “Carlo Besta,” Milan, Italy
- Department of Biomedical and Clinical Sciences “Luigi Sacco,” University of Milan, Milan, Italy
| | - Stephen G. Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut
- Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
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8
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Devigili G, Rinaldo S, Lombardi R, Cazzato D, Marchi M, Salvi E, Eleopra R, Lauria G. Diagnostic criteria for small fibre neuropathy in clinical practice and research. Brain 2019; 142:3728-3736. [PMID: 31665231 PMCID: PMC6906595 DOI: 10.1093/brain/awz333] [Citation(s) in RCA: 111] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/06/2019] [Accepted: 09/04/2019] [Indexed: 02/06/2023] Open
Abstract
The diagnostic criteria for small fibre neuropathy are not established, influencing the approach to patients in clinical practice, their access to disease-modifying and symptomatic treatments, the use of healthcare resources, and the design of clinical trials. To address these issues, we performed a reappraisal study of 150 patients with sensory neuropathy and a prospective and follow-up validation study of 352 new subjects with suspected sensory neuropathy. Small fibre neuropathy diagnostic criteria were based on deep clinical phenotyping, quantitative sensory testing (QST) and intraepidermal nerve fibre density (IENFD). Small fibre neuropathy was ruled out in 5 of 150 patients (3.3%) of the reappraisal study. Small fibre neuropathy was diagnosed at baseline of the validation study in 149 of 352 patients (42.4%) based on the combination between two clinical signs and abnormal QST and IENFD (69.1%), abnormal QST alone (5.4%), or abnormal IENFD alone (20.1%). Eight patients (5.4%) had abnormal QST and IENFD but no clinical signs. Further, 38 patients complained of sensory symptoms but showed no clinical signs. Of those, 34 (89.4%) had normal QST and IENFD, 4 (10.5%) had abnormal QST and normal IENFD, and none had abnormal IENFD alone. At 18-month follow-up, 19 of them (56%) reported the complete recovery of symptoms and showed normal clinical, QST and IENFD findings. None of those with one single abnormal test (QST or IENFD) developed clinical signs or showed abnormal findings on the other test. Conversely, all eight patients with abnormal QST and IENFD at baseline developed clinical signs at follow-up. The combination of clinical signs and abnormal QST and/or IENFD findings can more reliably lead to the diagnosis of small fibre neuropathy than the combination of abnormal QST and IENFD findings in the absence of clinical signs. Sensory symptoms alone should not be considered a reliable screening feature. Our findings demonstrate that the combined clinical, functional and structural approach to the diagnosis of small fibre neuropathy is reliable and relevant both for clinical practice and clinical trial design.
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Affiliation(s)
- Grazia Devigili
- Movement Disorders Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Sara Rinaldo
- Movement Disorders Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Raffaella Lombardi
- Neuroalgology Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Daniele Cazzato
- Neuroalgology Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Margherita Marchi
- Neuroalgology Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Erika Salvi
- Neuroalgology Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Roberto Eleopra
- Movement Disorders Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Giuseppe Lauria
- Neuroalgology Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
- Department of Biomedical and Clinical Sciences “Luigi Sacco”, University of Milan, Milan, Italy
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9
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Calvo M, Davies AJ, Hébert HL, Weir GA, Chesler EJ, Finnerup NB, Levitt RC, Smith BH, Neely GG, Costigan M, Bennett DL. The Genetics of Neuropathic Pain from Model Organisms to Clinical Application. Neuron 2019; 104:637-653. [PMID: 31751545 PMCID: PMC6868508 DOI: 10.1016/j.neuron.2019.09.018] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/05/2019] [Accepted: 09/12/2019] [Indexed: 12/14/2022]
Abstract
Neuropathic pain (NeuP) arises due to injury of the somatosensory nervous system and is both common and disabling, rendering an urgent need for non-addictive, effective new therapies. Given the high evolutionary conservation of pain, investigative approaches from Drosophila mutagenesis to human Mendelian genetics have aided our understanding of the maladaptive plasticity underlying NeuP. Successes include the identification of ion channel variants causing hyper-excitability and the importance of neuro-immune signaling. Recent developments encompass improved sensory phenotyping in animal models and patients, brain imaging, and electrophysiology-based pain biomarkers, the collection of large well-phenotyped population cohorts, neurons derived from patient stem cells, and high-precision CRISPR generated genetic editing. We will discuss how to harness these resources to understand the pathophysiological drivers of NeuP, define its relationship with comorbidities such as anxiety, depression, and sleep disorders, and explore how to apply these findings to the prediction, diagnosis, and treatment of NeuP in the clinic.
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Affiliation(s)
- Margarita Calvo
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alexander J Davies
- Neural Injury Group, Nuffield Department of Clinical Neuroscience, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Harry L Hébert
- Chronic Pain Research Group, Division of Population Health and Genomics, Mackenzie Building, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK
| | - Greg A Weir
- Neural Injury Group, Nuffield Department of Clinical Neuroscience, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | | | - Nanna B Finnerup
- Department of Clinical Medicine, Danish Pain Research Center, Aarhus University, Aarhus 8000, Denmark
| | - Roy C Levitt
- Department of Anesthesiology, Perioperative Medicine and Pain Management, and John T. MacDonald Foundation Department of Human Genetics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Blair H Smith
- Chronic Pain Research Group, Division of Population Health and Genomics, Mackenzie Building, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK
| | - G Gregory Neely
- Dr. John and Anne Chong Lab for Functional Genomics, Camperdown, University of Sydney, Sydney, NSW, Australia
| | - Michael Costigan
- Departments of Anesthesia and Neurobiology, Children's Hospital Boston and Harvard Medical School, Boston, MA, USA.
| | - David L Bennett
- Neural Injury Group, Nuffield Department of Clinical Neuroscience, John Radcliffe Hospital, University of Oxford, Oxford, UK.
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10
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Pollard KJ, Sharma AD, Moore MJ. Neural microphysiological systems for in vitro modeling of peripheral nervous system disorders. ACTA ACUST UNITED AC 2019. [DOI: 10.2217/bem-2019-0018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
PNS disease pathology is diverse and underappreciated. Peripheral neuropathy may result in sensory, motor or autonomic nerve dysfunction and can be induced by metabolic dysfunction, inflammatory dysfunction, cytotoxic pharmaceuticals, rare hereditary disorders or may be idiopathic. Current preclinical PNS disease research relies heavily on the use of rodent models. In vivo methods are effective but too time-consuming and expensive for high-throughput experimentation. Conventional in vitro methods can be performed with high throughput but lack the biological complexity necessary to directly model in vivo nerve structure and function. In this review, we survey in vitro PNS model systems and propose that 3D-bioengineered microphysiological nerve tissue can improve in vitro–in vivo extrapolation and expand the capabilities of in vitro PNS disease modeling.
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Affiliation(s)
- Kevin J Pollard
- Department of Biomedical Engineering, Tulane University, New Orleans, LA 70118, USA
| | | | - Michael J Moore
- Department of Biomedical Engineering, Tulane University, New Orleans, LA 70118, USA
- AxoSim, Inc., New Orleans, LA 70112, USA
- Tulane Brain Institute, Tulane University, New Orleans, LA 70118, USA
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11
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Campbell G, Licht-Mayer S, Mahad D. Targeting mitochondria to protect axons in progressive MS. Neurosci Lett 2019; 710:134258. [PMID: 31082453 DOI: 10.1016/j.neulet.2019.05.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 05/07/2019] [Accepted: 05/09/2019] [Indexed: 10/26/2022]
Abstract
Inflammatory demyelinating processes target the neuron, particularly axons and synapses, in multiple sclerosis (MS). There is a gathering body of evidence indicating molecular changes which converge on mitochondria within neurons in progressive forms of MS. The most reproducible changes are the increase in mitochondrial content within demyelinated axons and mitochondrial respiratory chain complex deficiency in neurons, which compromises the capacity to generate ATP. The resulting lack of ATP and the likely energy failure state and its coupling with an increase in demand for energy by the demyelinated axon, are particularly relevant to the long tracts such as corticospinal tracts with long projection axons. Recent work in our laboratory and that of our collaborators indicate the limited reflection of the mitochondrial changes within neurons in the experimental disease models. Enhancing the energy producing capacity of neurons to meet the increased energy demand of demyelinated axons is likely to be a novel neuroprotective strategy in progressive MS.
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Affiliation(s)
- Graham Campbell
- The Centre for Clinical Brain Science, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
| | - Simon Licht-Mayer
- The Centre for Clinical Brain Science, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK
| | - Don Mahad
- The Centre for Clinical Brain Science, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK.
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12
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Bennett DL, Clark AJ, Huang J, Waxman SG, Dib-Hajj SD. The Role of Voltage-Gated Sodium Channels in Pain Signaling. Physiol Rev 2019; 99:1079-1151. [DOI: 10.1152/physrev.00052.2017] [Citation(s) in RCA: 256] [Impact Index Per Article: 51.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Acute pain signaling has a key protective role and is highly evolutionarily conserved. Chronic pain, however, is maladaptive, occurring as a consequence of injury and disease, and is associated with sensitization of the somatosensory nervous system. Primary sensory neurons are involved in both of these processes, and the recent advances in understanding sensory transduction and human genetics are the focus of this review. Voltage-gated sodium channels (VGSCs) are important determinants of sensory neuron excitability: they are essential for the initial transduction of sensory stimuli, the electrogenesis of the action potential, and neurotransmitter release from sensory neuron terminals. Nav1.1, Nav1.6, Nav1.7, Nav1.8, and Nav1.9 are all expressed by adult sensory neurons. The biophysical characteristics of these channels, as well as their unique expression patterns within subtypes of sensory neurons, define their functional role in pain signaling. Changes in the expression of VGSCs, as well as posttranslational modifications, contribute to the sensitization of sensory neurons in chronic pain states. Furthermore, gene variants in Nav1.7, Nav1.8, and Nav1.9 have now been linked to human Mendelian pain disorders and more recently to common pain disorders such as small-fiber neuropathy. Chronic pain affects one in five of the general population. Given the poor efficacy of current analgesics, the selective expression of particular VGSCs in sensory neurons makes these attractive targets for drug discovery. The increasing availability of gene sequencing, combined with structural modeling and electrophysiological analysis of gene variants, also provides the opportunity to better target existing therapies in a personalized manner.
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Affiliation(s)
- David L. Bennett
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Alex J. Clark
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Jianying Huang
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Stephen G. Waxman
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Sulayman D. Dib-Hajj
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
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13
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McDermott LA, Weir GA, Themistocleous AC, Segerdahl AR, Blesneac I, Baskozos G, Clark AJ, Millar V, Peck LJ, Ebner D, Tracey I, Serra J, Bennett DL. Defining the Functional Role of Na V1.7 in Human Nociception. Neuron 2019; 101:905-919.e8. [PMID: 30795902 PMCID: PMC6424805 DOI: 10.1016/j.neuron.2019.01.047] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 12/03/2018] [Accepted: 01/18/2019] [Indexed: 12/17/2022]
Abstract
Loss-of-function mutations in NaV1.7 cause congenital insensitivity to pain (CIP); this voltage-gated sodium channel is therefore a key target for analgesic drug development. Utilizing a multi-modal approach, we investigated how NaV1.7 mutations lead to human pain insensitivity. Skin biopsy and microneurography revealed an absence of C-fiber nociceptors in CIP patients, reflected in a reduced cortical response to capsaicin on fMRI. Epitope tagging of endogenous NaV1.7 revealed the channel to be localized at the soma membrane, axon, axon terminals, and the nodes of Ranvier of induced pluripotent stem cell (iPSC) nociceptors. CIP patient-derived iPSC nociceptors exhibited an inability to properly respond to depolarizing stimuli, demonstrating that NaV1.7 is a key regulator of excitability. Using this iPSC nociceptor platform, we found that some NaV1.7 blockers undergoing clinical trials lack specificity. CIP, therefore, arises due to a profound loss of functional nociceptors, which is more pronounced than that reported in rodent models, or likely achievable following acute pharmacological blockade. VIDEO ABSTRACT.
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Affiliation(s)
- Lucy A McDermott
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Greg A Weir
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | | | - Andrew R Segerdahl
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Iulia Blesneac
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Georgios Baskozos
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Alex J Clark
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Val Millar
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK
| | - Liam J Peck
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Daniel Ebner
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK
| | - Irene Tracey
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Jordi Serra
- Department of Clinical Neurophysiology, King's College Hospital, London SE5 9RS, UK
| | - David L Bennett
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
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14
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Eijkenboom I, Sopacua M, Hoeijmakers JGJ, de Greef BTA, Lindsey P, Almomani R, Marchi M, Vanoevelen J, Smeets HJM, Waxman SG, Lauria G, Merkies ISJ, Faber CG, Gerrits MM. Yield of peripheral sodium channels gene screening in pure small fibre neuropathy. J Neurol Neurosurg Psychiatry 2019; 90:342-352. [PMID: 30554136 DOI: 10.1136/jnnp-2018-319042] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 11/01/2018] [Accepted: 11/18/2018] [Indexed: 12/19/2022]
Abstract
BACKGROUND Neuropathic pain is common in peripheral neuropathy. Recent genetic studies have linked pathogenic voltage-gated sodium channel (VGSC) variants to human pain disorders. Our aims are to determine the frequency of SCN9A, SCN10A and SCN11A variants in patients with pure small fibre neuropathy (SFN), analyse their clinical features and provide a rationale for genetic screening. METHODS Between September 2009 and January 2017, 1139 patients diagnosed with pure SFN at our reference centre were screened for SCN9A, SCN10A and SCN11A variants. Pathogenicity of variants was classified according to established guidelines of the Association for Clinical Genetic Science and frequencies were determined. Patients with SFN were grouped according to the VGSC variants detected, and clinical features were compared. RESULTS Among 1139 patients with SFN, 132 (11.6%) patients harboured 73 different (potentially) pathogenic VGSC variants, of which 50 were novel and 22 were found in ≥ 1 patient. The frequency of (potentially) pathogenic variants was 5.1% (n=58/1139) for SCN9A, 3.7% (n=42/1139) for SCN10A and 2.9% (n=33/1139) for SCN11A. Only erythromelalgia-like symptoms and warmth-induced pain were significantly more common in patients harbouring VGSC variants. CONCLUSION (Potentially) pathogenic VGSC variants are present in 11.6% of patients with pure SFN. Therefore, genetic screening of SCN9A, SCN10A and SCN11A should be considered in patients with pure SFN, independently of clinical features or underlying conditions.
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Affiliation(s)
- Ivo Eijkenboom
- Department of Genetics and Cell Biology, Clinical Genomics Unit, Maastricht University, Maastricht, The Netherlands.,MHeNs School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Maurice Sopacua
- MHeNs School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Neurology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Janneke G J Hoeijmakers
- MHeNs School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Neurology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Bianca T A de Greef
- MHeNs School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Neurology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Patrick Lindsey
- Department of Genetics and Cell Biology, Clinical Genomics Unit, Maastricht University, Maastricht, The Netherlands
| | - Rowida Almomani
- Department of Genetics and Cell Biology, Clinical Genomics Unit, Maastricht University, Maastricht, The Netherlands.,MHeNs School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Medical Laboratory Sciences, Jordan University of Science and Technology, Irbid, Jordan
| | - Margherita Marchi
- Neuroalgology Unit, IRCCS Fondazione Istituto Neurologico "Carlo Besta", Milan, Italy
| | - Jo Vanoevelen
- Department of Genetics and Cell Biology, Clinical Genomics Unit, Maastricht University, Maastricht, The Netherlands
| | - Hubertus J M Smeets
- Department of Genetics and Cell Biology, Clinical Genomics Unit, Maastricht University, Maastricht, The Netherlands.,MHeNs School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Stephen G Waxman
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut, USA.,Centre for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, Connecticut, USA
| | - Giuseppe Lauria
- Neuroalgology Unit, IRCCS Fondazione Istituto Neurologico "Carlo Besta", Milan, Italy.,Department of Biomedical and Clinical Sciences "Luigi Sacco", University of Milan, Milan, Italy
| | - Ingemar S J Merkies
- MHeNs School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Neurology, St. Elisabeth Hospital, Willemstad, Curaçao
| | - Catharina G Faber
- MHeNs School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Neurology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Monique M Gerrits
- Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
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15
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Sopacua M, Hoeijmakers JGJ, Merkies ISJ, Lauria G, Waxman SG, Faber CG. Small‐fiber neuropathy: Expanding the clinical pain universe. J Peripher Nerv Syst 2019; 24:19-33. [DOI: 10.1111/jns.12298] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/27/2018] [Accepted: 12/14/2018] [Indexed: 12/11/2022]
Affiliation(s)
- Maurice Sopacua
- Department of Neurology, School of Mental Health and NeuroscienceMaastricht University Medical Centre+ Maastricht The Netherlands
| | - Janneke G. J. Hoeijmakers
- Department of Neurology, School of Mental Health and NeuroscienceMaastricht University Medical Centre+ Maastricht The Netherlands
| | - Ingemar S. J. Merkies
- Department of Neurology, School of Mental Health and NeuroscienceMaastricht University Medical Centre+ Maastricht The Netherlands
- Department of NeurologySt. Elisabeth Hospital Willemstad Curaçao
| | - Giuseppe Lauria
- Neuroalgology UnitIRCCS Foundation, “Carlo Besta” Neurological Institute Milan Italy
- Department of Biomedical and Clinical Sciences “Luigi Sacco”University of Milan Milan Italy
| | - Stephen G. Waxman
- Department of NeurologyYale University School of Medicine New Haven Connecticut
- Center for Neuroscience and Regeneration ResearchVA Connecticut Healthcare System West Haven Connecticut
| | - Catharina G. Faber
- Department of Neurology, School of Mental Health and NeuroscienceMaastricht University Medical Centre+ Maastricht The Netherlands
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16
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Eijkenboom I, Sopacua M, Otten AB, Gerrits MM, Hoeijmakers JG, Waxman SG, Lombardi R, Lauria G, Merkies IS, Smeets HJ, Faber CG, Vanoevelen JM. Expression of pathogenic SCN9A mutations in the zebrafish: A model to study small-fiber neuropathy. Exp Neurol 2019; 311:257-264. [DOI: 10.1016/j.expneurol.2018.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 09/21/2018] [Accepted: 10/10/2018] [Indexed: 01/19/2023]
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17
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18
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Dieckmann G, Goyal S, Hamrah P. Neuropathic Corneal Pain: Approaches for Management. Ophthalmology 2017; 124:S34-S47. [PMID: 29055360 DOI: 10.1016/j.ophtha.2017.08.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 08/01/2017] [Accepted: 08/02/2017] [Indexed: 01/16/2023] Open
Abstract
Neuropathic pain is caused by a primary lesion or dysfunction of the nervous system and can occur in the cornea. However, neuropathic corneal pain (NCP) is currently an ill-defined disease. Patients with NCP are extremely challenging to manage, and evidence-based clinical recommendations for the management of patients with NCP are scarce. The objectives of this review are to provide guidelines for diagnosis and treatment of patients with NCP and to summarize current evidence-based literature in this area. We performed a systematic literature search of all relevant publications between 1966 and 2017. Treatment recommendations are, in part, based on methodologically sound randomized controlled trials (RCTs), demonstrating superiority to placebo or relevant control treatments, and on the consistency of evidence, degree of efficacy, and safety. In addition, the recommendations include our own extensive experience in the management of these patients over the past decade. A comprehensive algorithm, based on clinical evaluation and complementary tests, is presented for diagnosis and subcategorization of patients with NCP. Recommended first-line topical treatments include neuroregenerative and anti-inflammatory agents, and first-line systemic pharmacotherapy includes tricyclic antidepressants and an anticonvulsant. Second-line oral treatments recommended include an opioid-antagonist and opiate analgesics. Complementary and alternative treatments, such as cardiovascular exercise, acupuncture, omega-3 fatty acid supplementation, and gluten-free diet, may have additional benefits, as do potential noninvasive and invasive procedures in recalcitrant cases. Medication selection should be tailored on an individual basis, considering side effects, comorbidities, and levels of peripheral and centralized pain. Nevertheless, there is an urgent need for long-term studies and RCTs assessing the efficacy of treatments for NCP.
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Affiliation(s)
- Gabriela Dieckmann
- Cornea Service, New England Eye Center, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts; Center for Translational Ocular Immunology, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts
| | - Sunali Goyal
- Department of Ophthalmology, Jones Eye Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Pedram Hamrah
- Cornea Service, New England Eye Center, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts; Center for Translational Ocular Immunology, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts.
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19
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Nav1.7-A1632G Mutation from a Family with Inherited Erythromelalgia: Enhanced Firing of Dorsal Root Ganglia Neurons Evoked by Thermal Stimuli. J Neurosci 2017; 36:7511-22. [PMID: 27413160 DOI: 10.1523/jneurosci.0462-16.2016] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 06/06/2016] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED Voltage-gated sodium channel Nav1.7 is a central player in human pain. Mutations in Nav1.7 produce several pain syndromes, including inherited erythromelalgia (IEM), a disorder in which gain-of-function mutations render dorsal root ganglia (DRG) neurons hyperexcitable. Although patients with IEM suffer from episodes of intense burning pain triggered by warmth, the effects of increased temperature on DRG neurons expressing mutant Nav1.7 channels have not been well documented. Here, using structural modeling, voltage-clamp, current-clamp, and multielectrode array recordings, we have studied a newly identified Nav1.7 mutation, Ala1632Gly, from a multigeneration family with IEM. Structural modeling suggests that Ala1632 is a molecular hinge and that the Ala1632Gly mutation may affect channel gating. Voltage-clamp recordings revealed that the Nav1.7-A1632G mutation hyperpolarizes activation and depolarizes fast-inactivation, both gain-of-function attributes at the channel level. Whole-cell current-clamp recordings demonstrated increased spontaneous firing, lower current threshold, and enhanced evoked firing in rat DRG neurons expressing Nav1.7-A1632G mutant channels. Multielectrode array recordings further revealed that intact rat DRG neurons expressing Nav1.7-A1632G mutant channels are more active than those expressing Nav1.7 WT channels. We also showed that physiologically relevant thermal stimuli markedly increase the mean firing frequencies and the number of active rat DRG neurons expressing Nav1.7-A1632G mutant channels, whereas the same thermal stimuli only increase these parameters slightly in rat DRG neurons expressing Nav1.7 WT channels. The response of DRG neurons expressing Nav1.7-A1632G mutant channels upon increase in temperature suggests a cellular basis for warmth-triggered pain in IEM. SIGNIFICANCE STATEMENT Inherited erythromelalgia (IEM), a severe pain syndrome characterized by episodes of intense burning pain triggered by warmth, is caused by mutations in sodium channel Nav1.7, which are preferentially expressed in sensory and sympathetic neurons. More than 20 gain-of-function Nav1.7 mutations have been identified from IEM patients, but the question of how warmth triggers episodes of pain in IEM has not been well addressed. Combining multielectrode array, voltage-clamp, and current-clamp recordings, we assessed a newly identified IEM mutation (Nav1.7-A1632G) from a multigeneration family. Our data demonstrate gain-of-function attributes at the channel level and differential effects of physiologically relevant thermal stimuli on the excitability of DRG neurons expressing mutant and WT Nav1.7 channels, suggesting a cellular mechanism for warmth-triggered pain episodes in IEM patients.
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Rolyan H, Liu S, Hoeijmakers JG, Faber CG, Merkies IS, Lauria G, Black JA, Waxman SG. A painful neuropathy-associated Nav1.7 mutant leads to time-dependent degeneration of small-diameter axons associated with intracellular Ca2+ dysregulation and decrease in ATP levels. Mol Pain 2016; 12:1744806916674472. [PMID: 27821467 PMCID: PMC5102167 DOI: 10.1177/1744806916674472] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 08/10/2016] [Accepted: 08/16/2016] [Indexed: 11/25/2022] Open
Abstract
Small fiber neuropathy is a painful sensory nervous system disorder characterized by damage to unmyelinated C- and thinly myelinated Aδ- nerve fibers, clinically manifested by burning pain in the distal extremities and dysautonomia. The clinical onset in adulthood suggests a time-dependent process. The mechanisms that underlie nerve fiber injury in small fiber neuropathy are incompletely understood, although roles for energetic stress have been suggested. In the present study, we report time-dependent degeneration of neurites from dorsal root ganglia neurons in culture expressing small fiber neuropathy-associated G856D mutant Nav1.7 channels and demonstrate a time-dependent increase in intracellular calcium levels [Ca2+]i and reactive oxygen species, together with a decrease in ATP levels. Together with a previous clinical report of burning pain in the feet and hands associated with reduced levels of Na+/K+-ATPase in humans with high altitude sickness, the present results link energetic stress and reactive oxygen species production with the development of a painful neuropathy that preferentially affects small-diameter axons.
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Affiliation(s)
- Harshvardhan Rolyan
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Neuroscience and Regeneration Research Center, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Shujun Liu
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Neuroscience and Regeneration Research Center, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Janneke Gj Hoeijmakers
- Department of Neurology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Catharina G Faber
- Department of Neurology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Ingemar Sj Merkies
- Department of Neurology, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Neurology, St. Elisabeth Hospital, Willemstad, Curaçao
| | - Giuseppe Lauria
- Neuroalgology Unit, IRCCS, Carlo Besta Neurological Institute, Milan, Italy
| | - Joel A Black
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Neuroscience and Regeneration Research Center, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Neuroscience and Regeneration Research Center, VA Connecticut Healthcare System, West Haven, CT, USA
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SCN9A Variants May be Implicated in Neuropathic Pain Associated With Diabetic Peripheral Neuropathy and Pain Severity. Clin J Pain 2016; 31:976-82. [PMID: 25585270 PMCID: PMC4894774 DOI: 10.1097/ajp.0000000000000205] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Supplemental Digital Content is available in the text. Objectives: Previous studies have established the role of SCN9A in various pain conditions, including idiopathic small fiber neuropathy. In the present study, we interrogate the relationship between common and rare variants in SCN9A gene and chronic neuropathic pain associated with diabetic peripheral neuropathy. Design: Using a cohort of 938 patients of European ancestry with chronic neuropathic pain associated with diabetic peripheral neuropathy enrolled in 6 clinical studies and 2 controls (POPRES, n=2624 and Coriell, n=1029), we examined the relationship between SCN9A variants and neuropathic pain in a case-control study using a 2-stage design. The exonic regions of SCN9A were sequenced in a subset of 244 patients with neuropathic pain, and the variants discovered were compared with POPRES control (stage 1). The top associated variants were followed up by genotyping in the entire case collection and Coriell controls restricting the analysis to the matching patients from the United States and Canada only (stage 2). Results: Seven variants were found to be associated with neuropathic pain at the sequencing stage. Four variants (Asp1908Gly, Val991Leu/Met932Leu, and an intronic variant rs74449889) were confirmed by genotyping to occur at a higher frequency in cases than controls (odds ratios ∼2.1 to 2.6, P=0.05 to 0.009). Val991Leu/Met932Leu was also associated with the severity of pain as measured by pain score Numeric Rating Scale (NRS-11, P=0.047). Val991Leu/Met932Leu variants were in complete linkage disequilibrium and previously shown to cause hyperexcitability in dorsal root ganglia neurons. Conclusions: The association of SCN9A variants with neuropathic pain and pain severity suggests a role of SCN9A in the disease etiology of neuropathic pain.
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Au NPB, Kumar G, Asthana P, Tin C, Mak YL, Chan LL, Lam PKS, Ma CHE. Ciguatoxin reduces regenerative capacity of axotomized peripheral neurons and delays functional recovery in pre-exposed mice after peripheral nerve injury. Sci Rep 2016; 6:26809. [PMID: 27229176 PMCID: PMC4882531 DOI: 10.1038/srep26809] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 05/10/2016] [Indexed: 01/03/2023] Open
Abstract
Ciguatera fish poisoning (CFP) results from consumption of tropical reef fish containing ciguatoxins (CTXs). Pacific (P)-CTX-1 is among the most potent known CTXs and the predominant source of CFP in the endemic region responsible for the majority of neurological symptoms in patients. Chronic and persistent neurological symptoms occur in some CFP patients, which often result in incomplete functional recovery for years. However, the direct effects of exposure to CTXs remain largely unknown. In present study, we exposed mice to CTX purified from ciguatera fish sourced from the Pacific region. P-CTX-1 was detected in peripheral nerves within hours and persisted for two months after exposure. P-CTX-1 inhibited axonal regrowth from axotomized peripheral neurons in culture. P-CTX-1 exposure reduced motor function in mice within the first two weeks of exposure before returning to baseline levels. These pre-exposed animals exhibited delayed sensory and motor functional recovery, and irreversible motor deficits after peripheral nerve injury in which formation of functional synapses was impaired. These findings are consistent with reduced muscle function, as assessed by electromyography recordings. Our study provides strong evidence that the persistence of P-CTX-1 in peripheral nerves reduces the intrinsic growth capacity of peripheral neurons, resulting in delayed functional recovery after injury.
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Affiliation(s)
- Ngan Pan Bennett Au
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Hong Kong
| | - Gajendra Kumar
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Hong Kong
| | - Pallavi Asthana
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Hong Kong
| | - Chung Tin
- Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Hong Kong.,Centre for Biosystems, Neuroscience, and Nanotechnology, City University of Hong Kong, Tat Chee Avenue, Hong Kong
| | - Yim Ling Mak
- State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Hong Kong.,Shenzhen Key Laboratory for the Sustainable Use of Marine Biodiversity, Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
| | - Leo Lai Chan
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Hong Kong.,State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Hong Kong.,Shenzhen Key Laboratory for the Sustainable Use of Marine Biodiversity, Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
| | - Paul Kwan Sing Lam
- State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Hong Kong.,Shenzhen Key Laboratory for the Sustainable Use of Marine Biodiversity, Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen, China.,Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Hong Kong
| | - Chi Him Eddie Ma
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Hong Kong.,Centre for Biosystems, Neuroscience, and Nanotechnology, City University of Hong Kong, Tat Chee Avenue, Hong Kong.,State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Hong Kong
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Sodium Channels, Mitochondria, and Axonal Degeneration in Peripheral Neuropathy. Trends Mol Med 2016; 22:377-390. [DOI: 10.1016/j.molmed.2016.03.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 12/19/2022]
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Pappalardo LW, Black JA, Waxman SG. Sodium channels in astroglia and microglia. Glia 2016; 64:1628-45. [PMID: 26919466 DOI: 10.1002/glia.22967] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 12/27/2015] [Accepted: 01/04/2016] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium channels are required for electrogenesis in excitable cells. Their activation, triggered by membrane depolarization, generates transient sodium currents that initiate action potentials in neurons, cardiac, and skeletal muscle cells. Cells that have not traditionally been considered to be excitable (nonexcitable cells), including glial cells, also express sodium channels in physiological conditions as well as in pathological conditions. These channels contribute to multiple functional roles that are seemingly unrelated to the generation of action potentials. Here, we discuss the dynamics of sodium channel expression in astrocytes and microglia, and review evidence for noncanonical roles in effector functions of these cells including phagocytosis, migration, proliferation, ionic homeostasis, and secretion of chemokines/cytokines. We also examine possible mechanisms by which sodium channels contribute to the activity of glial cells, with an eye toward therapeutic implications for central nervous system disease. GLIA 2016;64:1628-1645.
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Affiliation(s)
- Laura W Pappalardo
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT
| | - Joel A Black
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT
| | - Stephen G Waxman
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT
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Han C, Huang J, Waxman SG. Sodium channel Nav1.8: Emerging links to human disease. Neurology 2016; 86:473-83. [PMID: 26747884 DOI: 10.1212/wnl.0000000000002333] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 10/07/2015] [Indexed: 12/19/2022] Open
Abstract
The NaV1.8 sodium channel, encoded by gene SCN10A, was initially termed sensory neuron-specific (SNS) due to prominent expression in primary sensory neurons including dorsal root ganglion (DRG) neurons. Early studies on rodent NaV1.8 demonstrated depolarized voltage dependence of channel inactivation, a slow rate of inactivation, and rapid recovery from inactivation. As a result of these biophysical properties, NaV1.8 supports repetitive firing in response to sustained depolarization. This article reviews recent studies that reveal multiple links of NaV1.8 to human disease: (1) It has recently been shown that functional attributes that distinguish NaV1.8 from other sodium channel subtypes are exaggerated in human NaV1.8; its influence on neuronal activity is thus greater than previously thought. (2) Gain-of-function mutations of NaV1.8 that produce DRG neuron hyperexcitability have been found in 3% of patients with painful neuropathy, establishing a role in pathogenesis. (3) NaV1.8 is ectopically expressed within Purkinje neurons in multiple sclerosis (MS), where it perturbs electrical activity. Recent evidence indicates that variants of SCN10A predict the degree of cerebellar dysfunction in MS. (4) Emerging evidence has linked SCN10A variants to disorders of cardiac rhythm, via mechanisms that may include an effect on cardiac innervation. Involvement of NaV1.8 in neurologic disease may have therapeutic implications. NaV1.8-specific blocking agents, under development, ameliorate pain and attenuate MS-like deficits in animal models. Recent studies suggest that pharmacogenomics may permit the matching of specific channel blocking agents to particular patients. The new links of NaV1.8 in human disease raise new questions, but also suggest new therapeutic strategies.
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Affiliation(s)
- Chongyang Han
- From the Department of Neurology, Yale University School of Medicine, New Haven; and the Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven
| | - Jianying Huang
- From the Department of Neurology, Yale University School of Medicine, New Haven; and the Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven
| | - Stephen G Waxman
- From the Department of Neurology, Yale University School of Medicine, New Haven; and the Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven.
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Ramírez M, Martínez-Martínez LA, Hernández-Quintela E, Velazco-Casapía J, Vargas A, Martínez-Lavín M. Small fiber neuropathy in women with fibromyalgia. An in vivo assessment using corneal confocal bio-microscopy. Semin Arthritis Rheum 2015; 45:214-9. [DOI: 10.1016/j.semarthrit.2015.03.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 03/01/2015] [Accepted: 03/13/2015] [Indexed: 01/25/2023]
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Estacion M, Vohra BPS, Liu S, Hoeijmakers J, Faber CG, Merkies ISJ, Lauria G, Black JA, Waxman SG. Ca2+ toxicity due to reverse Na+/Ca2+ exchange contributes to degeneration of neurites of DRG neurons induced by a neuropathy-associated Nav1.7 mutation. J Neurophysiol 2015; 114:1554-64. [PMID: 26156380 DOI: 10.1152/jn.00195.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 07/06/2015] [Indexed: 12/19/2022] Open
Abstract
Gain-of-function missense mutations in voltage-gated sodium channel Nav1.7 have been linked to small-fiber neuropathy, which is characterized by burning pain, dysautonomia and a loss of intraepidermal nerve fibers. However, the mechanistic cascades linking Nav1.7 mutations to axonal degeneration are incompletely understood. The G856D mutation in Nav1.7 produces robust changes in channel biophysical properties, including hyperpolarized activation, depolarized inactivation, and enhanced ramp and persistent currents, which contribute to the hyperexcitability exhibited by neurons containing Nav1.8. We report here that cell bodies and neurites of dorsal root ganglion (DRG) neurons transfected with G856D display increased levels of intracellular Na(+) concentration ([Na(+)]) and intracellular [Ca(2+)] following stimulation with high [K(+)] compared with wild-type (WT) Nav1.7-expressing neurons. Blockade of reverse mode of the sodium/calcium exchanger (NCX) or of sodium channels attenuates [Ca(2+)] transients evoked by high [K(+)] in G856D-expressing DRG cell bodies and neurites. We also show that treatment of WT or G856D-expressing neurites with high [K(+)] or 2-deoxyglucose (2-DG) does not elicit degeneration of these neurites, but that high [K(+)] and 2-DG in combination evokes degeneration of G856D neurites but not WT neurites. Our results also demonstrate that 0 Ca(2+) or blockade of reverse mode of NCX protects G856D-expressing neurites from degeneration when exposed to high [K(+)] and 2-DG. These results point to [Na(+)] overload in DRG neurons expressing mutant G856D Nav1.7, which triggers reverse mode of NCX and contributes to Ca(2+) toxicity, and suggest subtype-specific blockade of Nav1.7 or inhibition of reverse NCX as strategies that might slow or prevent axon degeneration in small-fiber neuropathy.
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Affiliation(s)
- M Estacion
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut; Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - B P S Vohra
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut; Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - S Liu
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut; Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - J Hoeijmakers
- Department of Neurology, University Medical Center Maastricht, Maastricht, the Netherlands
| | - C G Faber
- Department of Neurology, University Medical Center Maastricht, Maastricht, the Netherlands
| | - I S J Merkies
- Department of Neurology, University Medical Center Maastricht, Maastricht, the Netherlands; Department of Neurology, Spaarne Hospital, Hoofddorp, the Netherlands; and
| | - G Lauria
- Neuroalgology Unit IRCCS Foundation "Carlo Besta" Neurological Institute, Milan, Italy
| | - J A Black
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut; Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - S G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut; Center for Neuroscience and Regeneration Research, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut;
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Hoeijmakers JG, Faber CG, Merkies IS, Waxman SG. Painful peripheral neuropathy and sodium channel mutations. Neurosci Lett 2015; 596:51-9. [DOI: 10.1016/j.neulet.2014.12.056] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Revised: 12/22/2014] [Accepted: 12/29/2014] [Indexed: 12/19/2022]
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de Lera Ruiz M, Kraus RL. Voltage-Gated Sodium Channels: Structure, Function, Pharmacology, and Clinical Indications. J Med Chem 2015; 58:7093-118. [PMID: 25927480 DOI: 10.1021/jm501981g] [Citation(s) in RCA: 335] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The tremendous therapeutic potential of voltage-gated sodium channels (Na(v)s) has been the subject of many studies in the past and is of intense interest today. Na(v)1.7 channels in particular have received much attention recently because of strong genetic validation of their involvement in nociception. Here we summarize the current status of research in the Na(v) field and present the most relevant recent developments with respect to the molecular structure, general physiology, and pharmacology of distinct Na(v) channel subtypes. We discuss Na(v) channel ligands such as small molecules, toxins isolated from animal venoms, and the recently identified Na(v)1.7-selective antibody. Furthermore, we review eight characterized ligand binding sites on the Na(v) channel α subunit. Finally, we examine possible therapeutic applications of Na(v) ligands and provide an update on current clinical studies.
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Affiliation(s)
- Manuel de Lera Ruiz
- Merck Research Laboratories , 770 Sumneytown Pike, West Point, Pennsylvania 19486, United States
| | - Richard L Kraus
- Merck Research Laboratories , 770 Sumneytown Pike, West Point, Pennsylvania 19486, United States
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Ylikallio E, Konovalova S, Dhungana Y, Hilander T, Junna N, Partanen JV, Toppila JP, Auranen M, Tyynismaa H. Truncated HSPB1 causes axonal neuropathy and impairs tolerance to unfolded protein stress. BBA CLINICAL 2015; 3:233-42. [PMID: 26675522 PMCID: PMC4661565 DOI: 10.1016/j.bbacli.2015.03.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 02/28/2015] [Accepted: 03/03/2015] [Indexed: 11/26/2022]
Abstract
Background HSPB1 belongs to the family of small heat shock proteins (sHSP) that have importance in protection against unfolded protein stress, in cancer cells for escaping drug toxicity stress and in neurons for suppression of protein aggregates. sHSPs have a conserved α-crystalline domain (ACD), flanked by variable N- and C-termini, whose functions are not fully understood. Dominant missense variants in HSPB1, locating mostly to the ACD, have been linked to inherited neuropathy. Methods Patients underwent detailed clinical and neurophysiologic characterization. Disease causing variants were identified by exome or gene panel sequencing. Primary patient fibroblasts were used to investigate the effects of the dominant defective HSPB1 proteins. Results Frameshift variant predicting ablation of the entire C-terminus p.(Met169Cfs2*) of HSPB1 and a missense variant p.(Arg127Leu) were identified in patients with dominantly inherited motor-predominant axonal Charcot–Marie–Tooth neuropathy. We show that the truncated protein is stable and binds wild type HSPB1. Both mutations impaired the heat stress tolerance of the fibroblasts. This effect was particularly pronounced for the cells with the truncating variant, independent of heat-induced nuclear translocation and induction of global transcriptional heat response. Furthermore, the truncated HSPB1 increased cellular sensitivity to protein misfolding. Conclusion Our results suggest that truncation of the non-conserved C-terminus impairs the function of HSPB1 in cellular stress response. General significance sHSPs have important roles in prevention of protein aggregates that induce toxicity. We showed that C-terminal part of HSPB1 is critical for tolerance of unfolded protein stress, and when lacking causes axonal neuropathy in patients. C-terminal truncation of small heat shock protein HSPB1 causes neuropathy. Truncated HSPB1 is stable in patient fibroblasts and binds wild type HSPB1. C-terminus of HSPB1 is critical for tolerance to unfolded protein stress. Neuropathy may develop as a consequence of impaired cellular stress response.
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Key Words
- ACD, α-crystalline domain
- CADD, combined annotation dependent depletion
- CMT, Charcot–Marie–Tooth disease
- Charcot–Marie–Tooth neuropathy
- EMG, electromyography
- ENMG, electroneuromyography
- EVS, exome variant server
- HSPB1
- MUP, motor unit potential
- Protein misfolding
- QST, quantitative sensory testing
- SISu, Sequencing Initiative Suomi
- dHMN, distal hereditary motor neuropathy
- heat shock protein
- sHSP, small heat shock protein
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Affiliation(s)
- Emil Ylikallio
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland
| | - Svetlana Konovalova
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland
| | - Yogesh Dhungana
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland
| | - Taru Hilander
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland
| | - Nella Junna
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland
| | - Juhani V Partanen
- Department of Clinical Neurophysiology, Medical Imaging Center, Helsinki University Central Hospital, Finland
| | - Jussi P Toppila
- Department of Clinical Neurophysiology, Medical Imaging Center, Helsinki University Central Hospital, Finland
| | - Mari Auranen
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland ; Department of Neurology, Helsinki University Central Hospital, Helsinki 00290, Finland
| | - Henna Tyynismaa
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki 00290, Finland ; Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki 00290, Finland
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Aggarwal S, Kheirkhah A, Cavalcanti BM, Cruzat A, Colon C, Brown E, Borsook D, Prüss H, Hamrah P. Autologous Serum Tears for Treatment of Photoallodynia in Patients with Corneal Neuropathy: Efficacy and Evaluation with In Vivo Confocal Microscopy. Ocul Surf 2015; 13:250-62. [PMID: 26045233 DOI: 10.1016/j.jtos.2015.01.005] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 01/21/2015] [Accepted: 01/01/2015] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Patients suffering from corneal neuropathy may present with photoallodynia; i.e., increased light sensitivity, frequently with a normal slit-lamp examination. This study aimed to evaluate the efficacy of autologous serum tears (AST) for treatment of severe photoallodynia in corneal neuropathy and to correlate clinical findings with corneal subbasal nerve alterations by in vivo confocal microscopy (IVCM). METHODS Retrospective case control study with 16 patients with neuropathy-induced severe photoallodynia compared to 16 normal controls. Symptom severity, clinical examination and bilateral corneal IVCM scans were recorded. RESULTS All patients suffered from extreme photoallodynia (8.8±1.1) with no concurrent ocular surface disease. Subbasal nerves were significantly decreased at baseline in patients compared to controls; total nerve length (9208±1264 vs 24714±1056 μm/mm(2); P<.0001) and total nerve number (9.6±1.4 vs 28.6±2.0; P<.0001), respectively. Morphologically, significantly increased reflectivity (2.9±0.2 vs 1.8±0.1; P<.0001), beading (in 93.7%), and neuromas (in 62.5%) were seen. AST (3.6±2.1 months) resulted in significantly decreased symptom severity (1.6±1.7; P=.02). IVCM demonstrated significantly improved nerve parameters (P<.005), total nerve length (15451±1595 μm/mm(2)), number (13.9±2.1), and reflectivity (1.9±0.1). Beading and neuromas were seen in only 56.2% and 7.6% of patients. CONCLUSION Patients with corneal neuropathy-induced photoallodynia show profound alterations in corneal nerves. AST restores nerve topography through nerve regeneration, and this correlated with improvement in patient-reported photoallodynia. The data support the notion that corneal nerve damage results in alterations in afferent trigeminal pathways to produce photoallodynia.
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Affiliation(s)
- Shruti Aggarwal
- Ocular Surface Imaging Center, Cornea and Refractive Surgery Service, Massachusetts Eye & Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Ahmad Kheirkhah
- Ocular Surface Imaging Center, Cornea and Refractive Surgery Service, Massachusetts Eye & Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Bernardo M Cavalcanti
- Ocular Surface Imaging Center, Cornea and Refractive Surgery Service, Massachusetts Eye & Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Andrea Cruzat
- Ocular Surface Imaging Center, Cornea and Refractive Surgery Service, Massachusetts Eye & Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Clara Colon
- Ocular Surface Imaging Center, Cornea and Refractive Surgery Service, Massachusetts Eye & Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Emma Brown
- Ocular Surface Imaging Center, Cornea and Refractive Surgery Service, Massachusetts Eye & Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - David Borsook
- Pain/Analgesia Imaging Neuroscience (P.A.I.N.) Group, Department of Anesthesia, Boston Children's Hospital, Center for Pain and the Brain, Harvard Medical School, Waltham, MA, USA
| | - Harald Prüss
- Department of Neurology, Charité University Medicine Berlin, Germany
| | - Pedram Hamrah
- Ocular Surface Imaging Center, Cornea and Refractive Surgery Service, Massachusetts Eye & Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
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Neuropathies douloureuses et atteinte des petites fibres. Rev Neurol (Paris) 2014; 170:825-36. [DOI: 10.1016/j.neurol.2014.10.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 10/10/2014] [Indexed: 12/16/2022]
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Zhang Z, Schmelz M, Segerdahl M, Quiding H, Centerholt C, Juréus A, Carr TH, Whiteley J, Salter H, Kvernebo MS, Ørstavik K, Helås T, Kleggetveit IP, Lunden LK, Jørum E. Exonic mutations in SCN9A (NaV1.7) are found in a minority of patients with erythromelalgia. Scand J Pain 2014; 5:217-225. [DOI: 10.1016/j.sjpain.2014.09.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 09/03/2014] [Indexed: 10/24/2022]
Abstract
Abstract
Background and aim
“Gain-of-function” mutations in voltage-gated sodium channel NaV1.7 have been linked to erythromelalgia (EM), characterized by painful hot and red hands and feet. We investigated the proportion of patients with EM that carry a mutation in NaV1.7 or in other pain-related genes and studied possible clinical differences.
Methods
In this study, 48 patients with EM were screened for mutations in a total of 29 candidate genes, including all sodium channel subunits, transient receptor potential channels (TRPA1, TRPV1, TRPM8), neurotrophic factors (NGF, NGFR, BDNF, GDNF, NTRK1 and WNK1) and other known pain-related genes (CACNG2, KCNS1, COMT, P2RX3, TAC1, TACR1), using a combination of next generation sequencing and classical Sanger sequencing.
Results
In 7/48 patients protein-modifying mutations of NaV1.7 (P187L, I228M, I848T (n = 4) and N1245S) were identified. Patients with the I848T mutation could be identified clinically based on early onset and severity of the disease. In contrast, there were no clinical characteristics that differentiated the other patients with NaV1.7 mutation from those patients without. We also found more than twenty rare protein-modifying genetic variants in the genes coding for sodium channels (NaV1.8, NaV1.9, NaV1.6, NaV1.5, NaV2.1, SCN1B, SCN3B), transient receptor potential channel (TRPA1, TRPV1), and other pain-related targets (WNK1 and NGFR).
Conclusion
We conclude that functionally characterized mutations of NaV1.7 (I848T) are present only in a minority of patient with EM. Albeit the majority of patients (27/48) carried rare protein-modifying mutations the vast majority of those will most probably not be causally linked to their disease.
Implications
The key question remaining to be solved is the possible role of rare variants of NaV1.8, NaV1.9, or beta-subunits in provoking chronic pain conditions or even EM.
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Affiliation(s)
| | - Martin Schmelz
- Department of Anesthesiology Mannheim , Heidelberg University , Heidelberg , Germany
| | - Märta Segerdahl
- AstraZeneca R&D , Södertälje , Sweden
- Department of Physiology and Pharmacology , Karolinska Institute , Stockholm , Sweden
| | | | | | | | | | | | - Hugh Salter
- AstraZeneca Translational Science Centre , Department of Clinical Neuroscience , Karolinska Institutet , Karolinska , Sweden
| | | | - Kristin Ørstavik
- Section of Clinical Neurophysiology , Department of Neurology , Oslo University Hospital-Rikshospitalet , Oslo , Norway
| | - Tormod Helås
- Section of Clinical Neurophysiology , Department of Neurology , Oslo University Hospital-Rikshospitalet , Oslo , Norway
| | - Inge-Petter Kleggetveit
- Section of Clinical Neurophysiology , Department of Neurology , Oslo University Hospital-Rikshospitalet , Oslo , Norway
| | - Lars Kristian Lunden
- Section of Clinical Neurophysiology , Department of Neurology , Oslo University Hospital-Rikshospitalet , Oslo , Norway
| | - Ellen Jørum
- Section of Clinical Neurophysiology , Department of Neurology , Oslo University Hospital-Rikshospitalet , Oslo , Norway
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Hoeijmakers JGJ, Faber CG, Merkies ISJ, Waxman SG. Channelopathies, painful neuropathy, and diabetes: which way does the causal arrow point? Trends Mol Med 2014; 20:544-50. [PMID: 25008557 DOI: 10.1016/j.molmed.2014.06.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 06/09/2014] [Accepted: 06/12/2014] [Indexed: 12/13/2022]
Abstract
Diabetes mellitus, a major global health problem, is commonly associated with painful peripheral neuropathy, which can substantially erode quality of life. Despite its clinical importance, the pathophysiology of painful diabetic neuropathy is incompletely understood. It has traditionally been thought that diabetes may cause neuropathy in patients with appropriate genetic makeup. Here, we propose a hypothesis whereby painful neuropathy is not a complication of diabetes, but rather occurs as a result of mutations that, in parallel, confer vulnerability to injury in pancreatic β cells and pain-signaling dorsal root ganglion (DRG) neurons. We suggest that mutations of sodium channel NaV1.7, which is present in both cell types, may increase susceptibility for development of diabetes via β cell injury and produce painful neuropathy via a distinct effect on DRG neurons.
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Affiliation(s)
- Janneke G J Hoeijmakers
- Department of Neurology, Maastricht University Medical Center, Maastricht, 6202 AZ, The Netherlands
| | - Catharina G Faber
- Department of Neurology, Maastricht University Medical Center, Maastricht, 6202 AZ, The Netherlands
| | - Ingemar S J Merkies
- Department of Neurology, Maastricht University Medical Center, Maastricht, 6202 AZ, The Netherlands; Department of Neurology, Spaarne Hospital, Hoofddorp, 2130 AT, The Netherlands
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06515, USA; Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT 06515, USA.
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Brouwer BA, Merkies ISJ, Gerrits MM, Waxman SG, Hoeijmakers JGJ, Faber CG. Painful neuropathies: the emerging role of sodium channelopathies. J Peripher Nerv Syst 2014; 19:53-65. [PMID: 25250524 DOI: 10.1111/jns5.12071] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pain is a frequent debilitating feature reported in peripheral neuropathies with involvement of small nerve (Aδ and C) fibers. Voltage-gated sodium channels are responsible for the generation and conduction of action potentials in the peripheral nociceptive neuronal pathway where NaV 1.7, NaV 1.8, and NaV 1.9 sodium channels (encoded by SCN9A, SCN10A, and SCN11A) are preferentially expressed. The human genetic pain conditions inherited erythromelalgia and paroxysmal extreme pain disorder were the first to be linked to gain-of-function SCN9A mutations. Recent studies have expanded this spectrum with gain-of-function SCN9A mutations in patients with small fiber neuropathy and in a new syndrome of pain, dysautonomia, and small hands and small feet (acromesomelia). In addition, painful neuropathies have been recently linked to SCN10A mutations. Patch-clamp studies have shown that the effect of SCN9A mutations is dependent upon the cell-type background. The functional effects of a mutation in dorsal root ganglion (DRG) neurons and sympathetic neuron cells may differ per mutation, reflecting the pattern of expression of autonomic symptoms in patients with painful neuropathies who carry the mutation in question. Peripheral neuropathies may not always be length-dependent, as demonstrated in patients with initial facial and scalp pain symptoms with SCN9A mutations showing hyperexcitability in both trigeminal ganglion and DRG neurons. There is some evidence suggesting that gain-of-function SCN9A mutations can lead to degeneration of peripheral axons. This review will focus on the emerging role of sodium channelopathies in painful peripheral neuropathies, which could serve as a basis for novel therapeutic strategies.
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Affiliation(s)
- Brigitte A Brouwer
- Department of Anesthesiology and Pain Management, Maastricht University Medical Center, Maastricht, The Netherlands
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Themistocleous AC, Ramirez JD, Serra J, Bennett DLH. The clinical approach to small fibre neuropathy and painful channelopathy. Pract Neurol 2014; 14:368-79. [PMID: 24778270 PMCID: PMC4251302 DOI: 10.1136/practneurol-2013-000758] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Small fibre neuropathy (SFN) is characterised by structural injury selectively affecting small diameter sensory and/or autonomic axons. The clinical presentation is dominated by pain. SFN complicates a number of common diseases such as diabetes mellitus and is likely to be increasingly encountered. The diagnosis of SFN is demanding as clinical features can be vague and nerve conduction studies normal. New diagnostic techniques, in particular measurement of intraepidermal nerve fibre density, have significantly improved the diagnostic efficiency of SFN. Management is focused on the treatment of the underlying cause and analgesia, as there is no neuroprotective therapy. A recent and significant advance is the finding that a proportion of cases labelled as idiopathic SFN are in fact associated with gain of function mutations of the voltage-gated sodium channels Nav1.7 and Nav1.8 (encoded by the genes SCN9A and SCN10A, respectively). There is a further group of heritable painful conditions in which gain of function mutations in ion channels alter excitability of sensory neurones but do not cause frank axon degeneration; these include mutations in Nav1.7 (causing erythromelalgia and paroxysmal extreme pain disorder) and TRPA1 (resulting in familial episodic pain disorder). These conditions are exceptionally rare but have provided great insight into the nociceptive system as well as yielding potential analgesic drug targets. In patients with no pre-existing risk factor, the investigation of an underlying cause of SFN should be systematic and appropriate for the patient population. In this review, we focus on how to incorporate recent developments in the diagnosis and pathophysiology of SFN into clinical practice.
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Affiliation(s)
| | - Juan D Ramirez
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, Oxfordshire, UK
| | - Jordi Serra
- Neuroscience Technologies, Parc Científic de Barcelona, Barcelona, Spain Department of Neurology, MC Mutual, Barcelona, Spain
| | - David L H Bennett
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, Oxfordshire, UK
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Bennett DLH. Voltage-gated sodium channel mutations and painful neuropathy: Nav1.9 joins the family. Brain 2014; 137:1574-6. [DOI: 10.1093/brain/awu105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Pappalardo LW, Samad OA, Black JA, Waxman SG. Voltage-gated sodium channel Nav 1.5 contributes to astrogliosis in an in vitro model of glial injury via reverse Na+ /Ca2+ exchange. Glia 2014; 62:1162-75. [PMID: 24740847 DOI: 10.1002/glia.22671] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 03/25/2014] [Accepted: 03/27/2014] [Indexed: 12/19/2022]
Abstract
Astrogliosis is a prominent feature of many, if not all, pathologies of the brain and spinal cord, yet a detailed understanding of the underlying molecular pathways involved in the transformation from quiescent to reactive astrocyte remains elusive. We investigated the contribution of voltage-gated sodium channels to astrogliosis in an in vitro model of mechanical injury to astrocytes. Previous studies have shown that a scratch injury to astrocytes invokes dual mechanisms of migration and proliferation in these cells. Our results demonstrate that wound closure after mechanical injury, involving both migration and proliferation, is attenuated by pharmacological treatment with tetrodotoxin (TTX) and KB-R7943, at a dose that blocks reverse mode of the Na(+) /Ca(2+) exchanger (NCX), and by knockdown of Nav 1.5 mRNA. We also show that astrocytes display a robust [Ca(2+) ]i transient after mechanical injury and demonstrate that this [Ca(2+) ]i response is also attenuated by TTX, KB-R7943, and Nav 1.5 mRNA knockdown. Our results suggest that Nav 1.5 and NCX are potential targets for modulation of astrogliosis after injury via their effect on [Ca(2+) ]i .
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Affiliation(s)
- Laura W Pappalardo
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, Connecticut
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Paul D, Soignier RD, Minor L, Tau H, Songu-Mize E, Gould HJ. Regulation and pharmacological blockade of sodium-potassium ATPase: a novel pathway to neuropathy. J Neurol Sci 2014; 340:139-43. [PMID: 24661409 DOI: 10.1016/j.jns.2014.03.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 01/20/2014] [Accepted: 03/06/2014] [Indexed: 10/25/2022]
Abstract
Inflammation causes upregulation of NaV1.7 sodium channels in the associated dorsal root ganglia (DRG). The resultant increase in sodium influx must be countered to maintain osmotic homeostasis. The primary mechanism to pump sodium out of neurons is Na(+), K(+)-ATPase. To test whether there is a compensatory upregulation of Na(+), K(+)-ATPase after inflammation, rats received an injection of complete Freund's adjuvant (CFA) into one hindpaw and saline into the contralateral hindpaw. Three days later, L4-L6 DRGs were extracted and analyzed using gel electrophoresis and immunohistochemistry. Immunoreactivity for both the α-1 and α-3 subunits were increased in DRG associated with CFA-treatment, compared to saline-treatment. To test whether dysregulation of Na(+), K(+)-ATPase may cause cell death after inflammation, we produced a pharmacological blockade with ouabain (10mg/kg, s.c.) three days after CFA injection and paws were stimulated or not. Twenty-four hours later, DRG were removed and stained with cresyl violet. Greater cell death was seen in DRG from ouabain-treated animals on the CFA treated side than the saline-treated side. Paw stimulation doubled this difference. Control DRG showed little neuronal death. These results are evidence that regulation of Na(+), K(+)-ATPase during major inflammatory disease states is critical for homeostatic protection of primary afferent neurons.
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Affiliation(s)
- Dennis Paul
- Department of Pharmacology and Experimental Therapeutics, LSU Health Sciences Center, New Orleans, LA 70112, United States; Department of Neurology, LSU Health Sciences Center, New Orleans, LA 70112, United States; Department of Anesthesiology, LSU Health Sciences Center, New Orleans, LA 70112, United States; Department of Physical Medicine and Rehabilitation, LSU Health Sciences Center, New Orleans, LA 70112, United States; Neuroscience Center of Excellence, LSU Health Sciences Center, New Orleans, LA 70112, United States; Center of Excellence for Oral and Craniofacial Biology, LSU Health Sciences Center, New Orleans, LA 70112, United States; Alcohol and Drug Abuse Center of Excellence, LSU Health Sciences Center, New Orleans, LA 70112, United States.
| | - R Denis Soignier
- Department of Neurology, LSU Health Sciences Center, New Orleans, LA 70112, United States; Neuroscience Center of Excellence, LSU Health Sciences Center, New Orleans, LA 70112, United States
| | - Lerna Minor
- Department of Pharmacology and Experimental Therapeutics, LSU Health Sciences Center, New Orleans, LA 70112, United States
| | - Hui Tau
- Department of Neurology, LSU Health Sciences Center, New Orleans, LA 70112, United States
| | - Emel Songu-Mize
- Department of Pharmacology and Experimental Therapeutics, LSU Health Sciences Center, New Orleans, LA 70112, United States; Neuroscience Center of Excellence, LSU Health Sciences Center, New Orleans, LA 70112, United States
| | - Harry J Gould
- Department of Neurology, LSU Health Sciences Center, New Orleans, LA 70112, United States; Department of Anesthesiology, LSU Health Sciences Center, New Orleans, LA 70112, United States; Department of Physical Medicine and Rehabilitation, LSU Health Sciences Center, New Orleans, LA 70112, United States; Neuroscience Center of Excellence, LSU Health Sciences Center, New Orleans, LA 70112, United States; Center of Excellence for Oral and Craniofacial Biology, LSU Health Sciences Center, New Orleans, LA 70112, United States
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Sodium channels contribute to degeneration of dorsal root ganglion neurites induced by mitochondrial dysfunction in an in vitro model of axonal injury. J Neurosci 2014; 33:19250-61. [PMID: 24305821 DOI: 10.1523/jneurosci.2148-13.2013] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Axonal degeneration occurs in multiple neurodegenerative disorders of the central and peripheral nervous system. Although the underlying molecular pathways leading to axonal degeneration are incompletely understood, accumulating evidence suggests contributions of impaired mitochondrial function, disrupted axonal transport, and/or dysfunctional intracellular Ca(2+)-homeostasis in the injurious cascade associated with axonal degeneration. Utilizing an in vitro model of axonal degeneration, we studied a subset of mouse peripheral sensory neurons in which neurites were exposed selectively to conditions associated with the pathogenesis of axonal neuropathies in vivo. Rotenone-induced mitochondrial dysfunction resulted in neurite degeneration accompanied by reduced ATP levels and increased ROS levels in neurites. Blockade of voltage-gated sodium channels with TTX and reverse (Ca(2+)-importing) mode of the sodium-calcium exchanger (NCX) with KB-R7943 partially protected rotenone-treated neurites from degeneration, suggesting a contribution of sodium channels and reverse NCX activity to the degeneration of neurites resulting from impaired mitochondrial function. Pharmacological inhibition of the Na(+)/K(+)-ATPase with ouabain induced neurite degeneration, which was attenuated by TTX and KB-R7943, supporting a contribution of sodium channels in axonal degenerative pathways accompanying impaired Na(+)/K(+)-ATPase activity. Conversely, oxidant stress (H2O2)-induced neurite degeneration was not attenuated by TTX. Our results demonstrate that both energetic and oxidative stress targeted selectively to neurites induces neurite degeneration and that blockade of sodium channels and of reverse NCX activity blockade partially protects neurites from injury due to energetic stress, but not from oxidative stress induced by H2O2.
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Fairless R, Williams SK, Diem R. Dysfunction of neuronal calcium signalling in neuroinflammation and neurodegeneration. Cell Tissue Res 2013; 357:455-62. [PMID: 24326615 DOI: 10.1007/s00441-013-1758-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 10/31/2013] [Indexed: 02/07/2023]
Abstract
Neurodegeneration has been increasingly recognised as the leading structural correlate of disability progression in autoimmune diseases such as multiple sclerosis. Since calcium signalling is known to regulate the development of degenerative processes in many cell types, it is believed to play significant roles in mediating neurodegeneration. Because of its function as a major juncture linking various insults and injuries associated with inflammatory attack on neuronal cell bodies and axons, it provides potential for the development of neuroprotective strategies. This is of great significance because of the lack of neuroprotective agents presently available to supplement the current array of immunomodulatory treatments. In this review, we summarise the role that various calcium channels and pumps have been shown to play in the development of neurodegeneration under inflammatory autoimmune conditions. The identification of suitable targets might also provide insights into applications in non-inflammatory neurodegenerative diseases.
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Affiliation(s)
- Richard Fairless
- Department of Neuro-oncology, University Clinic Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
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46
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Small-fiber neuropathy Nav1.8 mutation shifts activation to hyperpolarized potentials and increases excitability of dorsal root ganglion neurons. J Neurosci 2013; 33:14087-97. [PMID: 23986244 DOI: 10.1523/jneurosci.2710-13.2013] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Idiopathic small-fiber neuropathy (I-SFN), clinically characterized by burning pain in distal extremities and autonomic dysfunction, is a disorder of small-caliber nerve fibers of unknown etiology with limited treatment options. Functional variants of voltage-gated sodium channel Nav1.7, encoded by SCN9A, have been identified in approximately one-third of I-SFN patients. These variants render dorsal root ganglion (DRG) neurons hyperexcitable. Sodium channel Nav1.8, encoded by SCN10A, is preferentially expressed in small-diameter DRG neurons, and produces most of the current underlying the upstroke of action potentials in these neurons. We previously demonstrated two functional variants of Nav1.8 that either enhance ramp current or shift activation in a hyperpolarizing direction, and render DRG neurons hyperexcitable, in I-SFN patients with no mutations of SCN9A. We have now evaluated additional I-SFN patients with no mutations in SCN9A, and report a novel I-SFN-related Nav1.8 mutation I1706V in a patient with painful I-SFN. Whole-cell voltage-clamp recordings in small DRG neurons demonstrate that the mutation hyperpolarizes activation and the response to slow ramp depolarizations. However, it decreases fractional channels resistant to fast inactivation and reduces persistent currents. Current-clamp studies reveal that mutant channels decrease current threshold and increase the firing frequency of evoked action potentials within small DRG neurons. These observations suggest that the effects of this mutation on activation and ramp current are dominant over the reduced persistent current, and show that these pro-excitatory gating changes confer hyperexcitability on peripheral sensory neurons, which may contribute to pain in this individual with I-SFN.
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Targeted next-generation sequencing reveals further genetic heterogeneity in axonal Charcot-Marie-Tooth neuropathy and a mutation in HSPB1. Eur J Hum Genet 2013; 22:522-7. [PMID: 23963299 DOI: 10.1038/ejhg.2013.190] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 07/19/2013] [Accepted: 07/24/2013] [Indexed: 12/11/2022] Open
Abstract
Charcot-Marie-Tooth disease (CMT) is a group of hereditary peripheral neuropathies. The dominantly inherited axonal CMT2 displays striking genetic heterogeneity, with 17 presently known disease genes. The large number of candidate genes, combined with lack of genotype-phenotype correlations, has made genetic diagnosis in CMT2 time-consuming and costly. In Finland, 25% of dominant CMT2 is explained by either a GDAP1 founder mutation or private MFN2 mutations but the rest of the families have remained without molecular diagnosis. Whole-exome and genome sequencing are powerful techniques to find disease mutations for CMT patients but they require large amounts of sequencing to confidently exclude heterozygous variants in all candidate genes, and they generate a vast amount of irrelevant data for diagnostic needs. Here we tested a targeted next-generation sequencing approach to screen the CMT2 genes. In total, 15 unrelated patients from dominant CMT2 families from Finland, in whom MFN2 and GDAP1 mutations had been excluded, participated in the study. The targeted approach produced sufficient sequence coverage for 95% of the 309 targeted exons, the rest we excluded by Sanger sequencing. Unexpectedly, the screen revealed a disease mutation only in one family, in the HSPB1 gene. Thus, new disease genes underlie CMT2 in the remaining families, indicating further genetic heterogeneity. We conclude that targeted next-generation sequencing is an efficient tool for genetic screening in CMT2 that also aids in the selection of patients for genome-wide approaches.
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Rahman W, Dickenson AH. Voltage gated sodium and calcium channel blockers for the treatment of chronic inflammatory pain. Neurosci Lett 2013; 557 Pt A:19-26. [PMID: 23941888 DOI: 10.1016/j.neulet.2013.08.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/30/2013] [Accepted: 08/01/2013] [Indexed: 01/16/2023]
Abstract
The inflammatory response is a natural response of the body that occurs immediately following tissue damage, which may be due to injury, infection or disease. The acute inflammatory response is an essential mechanism that promotes healing and a key aspect is the ensuing pain, which warns the subject to protect the site of injury. Thus, it is common to see a zone of primary sensitization as well as consequential central sensitization that generally, is maintained by a peripheral drive from the zone of tissue injury. Inflammation associated with chronic pain states, such as rheumatoid and osteoarthritis, cancer and migraine etc. is deleterious to health and often debilitating for the patient. Thus there is a large unmet clinical need. The mechanisms underlying both acute and chronic inflammatory pain are extensive and complex, involving a diversity of cell types, receptors and proteins. Among these the contribution of voltage gated sodium and calcium channels on peripheral nociceptors is critical for nociceptive transmission beyond the peripheral transducers and changes in their distribution, accumulation, clustering and functional activities have been linked to both inflammatory and neuropathic pain. The latter has been the main area for trials and use of drugs that modulate ion channels such as carbamazepine and gabapentin, but given the large peripheral drive that follows tissue damage, there is a clear rationale for blocking voltage gated sodium and calcium channels in these pain states. It has been hypothesized that pain of inflammatory origin may evolve into a condition that resembles neuropathic pain, but mixed pains such as low back pain and cancer pain often include elements of both pain states. This review considers the therapeutic potential for sodium and calcium channel blockers for the treatment of chronic inflammatory pain states.
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Affiliation(s)
- Wahida Rahman
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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49
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Faber CG, Lauria G, Merkies ISJ, Cheng X, Han C, Ahn HS, Persson AK, Hoeijmakers JGJ, Gerrits MM, Pierro T, Lombardi R, Kapetis D, Dib-Hajj SD, Waxman SG. Gain-of-function Nav1.8 mutations in painful neuropathy. Proc Natl Acad Sci U S A 2012; 109:19444-9. [PMID: 23115331 PMCID: PMC3511073 DOI: 10.1073/pnas.1216080109] [Citation(s) in RCA: 309] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Painful peripheral neuropathy often occurs without apparent underlying cause. Gain-of-function variants of sodium channel Na(v)1.7 have recently been found in ∼30% of cases of idiopathic painful small-fiber neuropathy. Here, we describe mutations in Na(v)1.8, another sodium channel that is specifically expressed in dorsal root ganglion (DRG) neurons and peripheral nerve axons, in patients with painful neuropathy. Seven Na(v)1.8 mutations were identified in 9 subjects within a series of 104 patients with painful predominantly small-fiber neuropathy. Three mutations met criteria for potential pathogenicity based on predictive algorithms and were assessed by voltage and current clamp. Functional profiling showed that two of these three Na(v)1.8 mutations enhance the channel's response to depolarization and produce hyperexcitability in DRG neurons. These observations suggest that mutations of Na(v)1.8 contribute to painful peripheral neuropathy.
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Affiliation(s)
| | | | - Ingemar S. J. Merkies
- Departments of Neurology and
- Department of Neurology, Spaarne Hospital, 2130 AT Hoofddorp, The Netherlands
| | - Xiaoyang Cheng
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510; and
- Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT 06516
| | - Chongyang Han
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510; and
- Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT 06516
| | - Hye-Sook Ahn
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510; and
- Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT 06516
| | - Anna-Karin Persson
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510; and
- Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT 06516
| | | | - Monique M. Gerrits
- Clinical Genomics, University Medical Centre Maastricht, 6202 AZ Maastricht, The Netherlands
| | | | | | - Dimos Kapetis
- Neuromuscular Diseases Unit and
- Bioinformatics Unit, Istituto di Ricovero e Cura a Carattere Scientifico Foundation, “Carlo Besta,” 20133 Milan, Italy
| | - Sulayman D. Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510; and
- Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT 06516
| | - Stephen G. Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510; and
- Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT 06516
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