1
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Price T, Shiers S, Mazhar K, Wangzhou A, Haberberger R, Lesnak J, Sankaranarayanan I, Tavares-Ferreira D, Cervantes A, Funk G, Horton P, Vines E, Dussor G. Nageotte nodules in human DRG reveal neurodegeneration in painful diabetic neuropathy. RESEARCH SQUARE 2024:rs.3.rs-5006011. [PMID: 39399674 PMCID: PMC11469377 DOI: 10.21203/rs.3.rs-5006011/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2024]
Abstract
Diabetic neuropathy is frequently accompanied by pain and loss of sensation attributed to axonal dieback. We recovered dorsal root ganglia (DRGs) from 90 organ donors, 19 of whom had medical indices for diabetic painful neuropathy (DPN). Nageotte nodules, dead sensory neurons engulfed by non-neuronal cells, were abundant in DPN DRGs and accounted for 25% of all neurons. Peripherin-and Nav1.7-positive dystrophic axons invaded Nageotte nodules, forming small neuroma-like structures. Using histology and spatial sequencing, we demonstrate that Nageotte nodules are mainly composed of satellite glia and non-myelinating Schwann cells that express SPP1 and are intertwined with sprouting sensory axons originating from neighboring neurons. Our findings solve a 100-year mystery of the nature of Nageotte nodules linking these pathological structures to pain and sensory loss in DPN.
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2
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De Stefano G, Truini A. An overview of diagnosis and assessment methods for neuropathic pain. Presse Med 2024; 53:104234. [PMID: 38636786 DOI: 10.1016/j.lpm.2024.104234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 04/04/2024] [Indexed: 04/20/2024] Open
Abstract
Neuropathic pain, defined as pain arising as a consequence of a lesion or disease affecting the somatosensory nervous system, requires precise diagnostic assessment. Different diagnostic tools have been devised for the diagnosis of neuropathic pain. This review offers insights into the diagnostic accuracy of screening questionnaires and different tests that investigate the somatosensory nervous system, in patients with suspected neuropathic pain. Thus, it illustrates how these tools can aid clinicians in accurately diagnosing neuropathic pain.
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Affiliation(s)
| | - Andrea Truini
- Sapienza University, Department of Human Neuroscience, Rome, Italy.
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3
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George DS, Jayaraj ND, Pacifico P, Ren D, Sriram N, Miller RE, Malfait AM, Miller RJ, Menichella DM. The Mas-related G protein-coupled receptor d (Mrgprd) mediates pain hypersensitivity in painful diabetic neuropathy. Pain 2024; 165:1154-1168. [PMID: 38147415 PMCID: PMC11017747 DOI: 10.1097/j.pain.0000000000003120] [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: 04/18/2023] [Revised: 08/22/2023] [Accepted: 08/22/2023] [Indexed: 12/28/2023]
Abstract
ABSTRACT Painful diabetic neuropathy (PDN) is one of the most common and intractable complications of diabetes. Painful diabetic neuropathy is characterized by neuropathic pain accompanied by dorsal root ganglion (DRG) nociceptor hyperexcitability, axonal degeneration, and changes in cutaneous innervation. However, the complete molecular profile underlying the hyperexcitable cellular phenotype of DRG nociceptors in PDN has not been elucidated. This gap in our knowledge is a critical barrier to developing effective, mechanism-based, and disease-modifying therapeutic approaches that are urgently needed to relieve the symptoms of PDN. Using single-cell RNA sequencing of DRGs, we demonstrated an increased expression of the Mas-related G protein-coupled receptor d (Mrgprd) in a subpopulation of DRG neurons in the well-established high-fat diet (HFD) mouse model of PDN. Importantly, limiting Mrgprd signaling reversed mechanical allodynia in the HFD mouse model of PDN. Furthermore, in vivo calcium imaging allowed us to demonstrate that activation of Mrgprd-positive cutaneous afferents that persist in diabetic mice skin resulted in an increased intracellular calcium influx into DRG nociceptors that we assess in vivo as a readout of nociceptors hyperexcitability. Taken together, our data highlight a key role of Mrgprd-mediated DRG neuron excitability in the generation and maintenance of neuropathic pain in a mouse model of PDN. Hence, we propose Mrgprd as a promising and accessible target for developing effective therapeutics currently unavailable for treating neuropathic pain in PDN.
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Affiliation(s)
| | | | | | - Dongjun Ren
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | | | - Rachel E. Miller
- Department of Internal Medicine, Rush Medical College, Chicago, IL, United States
| | - Anne-Marie Malfait
- Department of Internal Medicine, Rush Medical College, Chicago, IL, United States
| | - Richard J. Miller
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Daniela Maria Menichella
- Departments of Neurology and
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
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4
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Choi D, Goodwin G, Stevens EB, Soliman N, Namer B, Denk F. Spontaneous activity in peripheral sensory nerves: a systematic review. Pain 2024; 165:983-996. [PMID: 37991272 PMCID: PMC11017746 DOI: 10.1097/j.pain.0000000000003115] [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: 06/20/2023] [Revised: 08/29/2023] [Accepted: 09/23/2023] [Indexed: 11/23/2023]
Abstract
ABSTRACT In the peripheral nervous system, spontaneous activity in sensory neurons is considered to be one of the 2 main drivers of chronic pain states, alongside neuronal sensitization. Despite this, the precise nature and timing of this spontaneous activity in neuropathic pain is not well-established. Here, we have performed a systematic search and data extraction of existing electrophysiological literature to shed light on which fibre types have been shown to maintain spontaneous activity and over what time frame. We examined both in vivo recordings of preclinical models of neuropathic pain, as well as microneurography recordings in humans. Our analyses reveal that there is broad agreement on the presence of spontaneous activity in neuropathic pain conditions, even months after injury or years after onset of neuropathic symptoms in humans. However, because of the highly specialised nature of the electrophysiological methods used to measure spontaneous activity, there is also a high degree of variability and uncertainty around these results. Specifically, there are very few directly controlled experiments, with less directly comparable data between human and animals. Given that spontaneous peripheral neuron activity is considered to be a key mechanistic feature of chronic pain conditions, it may be beneficial to conduct further experiments in this space.
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Affiliation(s)
- Dongchan Choi
- Wolfson Centre for Age-Related Diseases, Guy's Campus, King's College London, London, United Kingdom
| | - George Goodwin
- Wolfson Centre for Age-Related Diseases, Guy's Campus, King's College London, London, United Kingdom
| | - Edward B. Stevens
- Metrion Biosciences Ltd, Building 2 Granta Centre, Granta Park, Cambridge, United Kingdom
| | - Nadia Soliman
- Imperial College London, Pain Research Group, Chelsea and Westminster Hospital, London, United Kingdom
| | - Barbara Namer
- Research Group Neuroscience of the Interdisziplinary Center for Clinical Research, University Hospital of the RWTH Aachen, Aachen, Germany
- Institute for Physiology, University Hospital of the RWTH Aachen, Aachen, Germany
| | - Franziska Denk
- Wolfson Centre for Age-Related Diseases, Guy's Campus, King's College London, London, United Kingdom
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5
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Sommer C, Baron R, Sachau J, Papagianni A, Özgül ÖS, Enax-Krumova E. [The EAN-NeuPSIG guideline on the diagnosis of neuropathic pain-a summary]. Schmerz 2024:10.1007/s00482-024-00806-0. [PMID: 38602515 DOI: 10.1007/s00482-024-00806-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2024] [Indexed: 04/12/2024]
Abstract
In this joint guideline of the scientific societies and working groups mentioned in the title, evidence-based recommendations for the use of screening questionnaires and diagnostic tests in patients with neuropathic pain were developed. The systematic literature search and meta-analysis yielded the following results: Of the screening questionnaires, Douleur Neuropathique en 4 Questions (DN4), I‑DN4 (self-administered DN4), and Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) received a strong recommendation, while S‑LANSS (self-administered LANSS) and PainDETECT received weak recommendations for their use in the diagnostic workup of patients with possible neuropathic pain. There was a strong recommendation for the use of skin biopsy and a weak recommendation for quantitative sensory testing and nociceptive evoked potentials. The role of confocal corneal microscopy is still unclear. Functional imaging and peripheral nerve blocks are helpful in elucidating the pathophysiology, but current literature does not support their use in diagnosing neuropathic pain. In selected cases, genetic testing in specialized centers may be considered.
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Affiliation(s)
- Claudia Sommer
- Neurologische Klinik, Universitätsklinikum Würzburg, 97080, Würzburg, Deutschland.
| | - Ralf Baron
- Sektion Neurologische Schmerzforschung und -therapie, Klinik für Neurologie, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel, Deutschland
| | - Juliane Sachau
- Sektion Neurologische Schmerzforschung und -therapie, Klinik für Neurologie, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel, Deutschland
| | | | - Özüm S Özgül
- Neurologische Klinik und Poliklinik, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil gGmbH, Ruhr-Universität Bochum, Bochum, Deutschland
| | - Elena Enax-Krumova
- Neurologische Klinik und Poliklinik, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil gGmbH, Ruhr-Universität Bochum, Bochum, Deutschland
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6
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Wang Q, Ye Y, Yang L, Xiao L, Liu J, Zhang W, Du G. Painful diabetic neuropathy: The role of ion channels. Biomed Pharmacother 2024; 173:116417. [PMID: 38490158 DOI: 10.1016/j.biopha.2024.116417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 03/06/2024] [Accepted: 03/06/2024] [Indexed: 03/17/2024] Open
Abstract
Painful diabetic neuropathy (PDN) is a common chronic complication of diabetes that causes neuropathic pain and negatively affects the quality of life. The management of PDN is far from satisfactory. At present, interventions are primarily focused on symptomatic treatment. Ion channel disorders are a major cause of PDN, and a complete understanding of their roles and mechanisms may provide better options for the clinical treatment of PDN. Therefore, this review summarizes the important role of ion channels in PDN and the current drug development targeting these ion channels.
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Affiliation(s)
- Qi Wang
- Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Centre, West China Hospital, Sichuan University, Chengdu, China; National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China
| | - Yifei Ye
- Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Centre, West China Hospital, Sichuan University, Chengdu, China; National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China
| | - Linghui Yang
- Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Centre, West China Hospital, Sichuan University, Chengdu, China; National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China
| | - Lifan Xiao
- Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Centre, West China Hospital, Sichuan University, Chengdu, China; National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China
| | - Jin Liu
- Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Centre, West China Hospital, Sichuan University, Chengdu, China; National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China
| | - Wensheng Zhang
- Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Centre, West China Hospital, Sichuan University, Chengdu, China; National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China.
| | - Guizhi Du
- Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Centre, West China Hospital, Sichuan University, Chengdu, China; National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China.
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7
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Antunes FTT, Huang S, Chen L, Zamponi GW. Effect of ABT-639 on Cav3.2 channel activity and its analgesic actions in mouse models of inflammatory and neuropathic pain. Eur J Pharmacol 2024; 967:176416. [PMID: 38342359 DOI: 10.1016/j.ejphar.2024.176416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/07/2024] [Accepted: 02/09/2024] [Indexed: 02/13/2024]
Abstract
Cav3.2 T-type calcium channels are important targets for pain relief in rodent models of inflammatory and neuropathic pain. Even though many T-type channel blockers have been tested in mice, only one molecule, ABT-639, has been tested in phase II clinical studies and did not produce analgesic effects over placebo. Here we examined the effects of ABT-639 on Cav3.2 channel activity in tsA-201 cells and dorsal root ganglion (DRG) neurons, in comparison with another established Cav3.2 inhibitor Z944. These experiments revealed that Z944 mediated ∼100-fold more potent inhibition of Cav3.2 currents than ABT-639, with the latter blocking channel activity by less than 15 percent when applied at a concentration of 30 μM. A slight increase in ABT-639 potency was observed at more depolarized holding potentials, suggesting that this compound may act preferentially on inactivated channels. We tested the effects of both compounds in the Complete Freund's Adjuvant (CFA) model of chronic inflammatory pain, and in partial sciatic nerve injury model of neuropathic pain in mice. In the neuropathic pain model, both Z944 and ABT-639 reversed mechanical hypersensitivity to similar degrees when delivered systemically, but remarkably, when delivered intrathecally, only Z944 was effective. In the CFA model, both compounds reversed thermal hyperalgesia upon systemic delivery, but only Z944 mediated pain relief upon intrathecal delivery, indicating that ABT-639 acts primarily at peripheral sites. ABT-639 lost its analgesic effects in CFA treated Cav3.2 null mice, indicating that these channels are essential for ABT-639-mediated pain relief despite its poor inhibition of Cav3.2 currents.
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Affiliation(s)
- Flavia Tasmin Techera Antunes
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, University of Calgary, AB, T2N 4N1, Calgary, Canada
| | - Sun Huang
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, University of Calgary, AB, T2N 4N1, Calgary, Canada
| | - Lina Chen
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, University of Calgary, AB, T2N 4N1, Calgary, Canada
| | - Gerald W Zamponi
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, University of Calgary, AB, T2N 4N1, Calgary, Canada.
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8
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Pacifico P, Coy-Dibley JS, Miller RJ, Menichella DM. Peripheral mechanisms of peripheral neuropathic pain. Front Mol Neurosci 2023; 16:1252442. [PMID: 37781093 PMCID: PMC10537945 DOI: 10.3389/fnmol.2023.1252442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 08/14/2023] [Indexed: 10/03/2023] Open
Abstract
Peripheral neuropathic pain (PNP), neuropathic pain that arises from a damage or disease affecting the peripheral nervous system, is associated with an extremely large disease burden, and there is an increasing and urgent need for new therapies for treating this disorder. In this review we have highlighted therapeutic targets that may be translated into disease modifying therapies for PNP associated with peripheral neuropathy. We have also discussed how genetic studies and novel technologies, such as optogenetics, chemogenetics and single-cell RNA-sequencing, have been increasingly successful in revealing novel mechanisms underlying PNP. Additionally, consideration of the role of non-neuronal cells and communication between the skin and sensory afferents is presented to highlight the potential use of drug treatment that could be applied topically, bypassing drug side effects. We conclude by discussing the current difficulties to the development of effective new therapies and, most importantly, how we might improve the translation of targets for peripheral neuropathic pain identified from studies in animal models to the clinic.
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Affiliation(s)
- Paola Pacifico
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - James S. Coy-Dibley
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Richard J. Miller
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Daniela M. Menichella
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
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9
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Truini A, Aleksovska K, Anderson CC, Attal N, Baron R, Bennett DL, Bouhassira D, Cruccu G, Eisenberg E, Enax-Krumova E, Davis KD, Di Stefano G, Finnerup NB, Garcia-Larrea L, Hanafi I, Haroutounian S, Karlsson P, Rakusa M, Rice ASC, Sachau J, Smith BH, Sommer C, Tölle T, Valls-Solé J, Veluchamy A. Joint European Academy of Neurology-European Pain Federation-Neuropathic Pain Special Interest Group of the International Association for the Study of Pain guidelines on neuropathic pain assessment. Eur J Neurol 2023; 30:2177-2196. [PMID: 37253688 DOI: 10.1111/ene.15831] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 04/03/2023] [Accepted: 04/12/2023] [Indexed: 06/01/2023]
Abstract
BACKGROUND AND PURPOSE In these guidelines, we aimed to develop evidence-based recommendations for the use of screening questionnaires and diagnostic tests in patients with neuropathic pain (NeP). METHODS We systematically reviewed studies providing information on the sensitivity and specificity of screening questionnaires, and quantitative sensory testing, neurophysiology, skin biopsy, and corneal confocal microscopy. We also analysed how functional neuroimaging, peripheral nerve blocks, and genetic testing might provide useful information in diagnosing NeP. RESULTS Of the screening questionnaires, Douleur Neuropathique en 4 Questions (DN4), I-DN4 (self-administered DN4), and Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) received a strong recommendation, and S-LANSS (self-administered LANSS) and PainDETECT weak recommendations for their use in the diagnostic pathway for patients with possible NeP. We devised a strong recommendation for the use of skin biopsy and a weak recommendation for quantitative sensory testing and nociceptive evoked potentials in the NeP diagnosis. Trigeminal reflex testing received a strong recommendation in diagnosing secondary trigeminal neuralgia. Although many studies support the usefulness of corneal confocal microscopy in diagnosing peripheral neuropathy, no study specifically investigated the diagnostic accuracy of this technique in patients with NeP. Functional neuroimaging and peripheral nerve blocks are helpful in disclosing pathophysiology and/or predicting outcomes, but current literature does not support their use for diagnosing NeP. Genetic testing may be considered at specialist centres, in selected cases. CONCLUSIONS These recommendations provide evidence-based clinical practice guidelines for NeP diagnosis. Due to the poor-to-moderate quality of evidence identified by this review, future large-scale, well-designed, multicentre studies assessing the accuracy of diagnostic tests for NeP are needed.
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Affiliation(s)
- Andrea Truini
- Department of Human Neuroscience, University Sapienza, Rome, Italy
| | - Katina Aleksovska
- European Academy of Neurology, Vienna, Austria
- Department of Neurology, Ss. Cyril and Methodius University, Skopje, North Macedonia
| | - Christopher C Anderson
- Division of Clinical and Translational Research, Department of Anesthesiology, Pain Center, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Nadine Attal
- Université Versailles Saint Quentin en Yvelines, Versailles, France
- Inserm U987, Pathophysiology and Clinical Pharmacology of Pain, Centre d'évaluation et de Traitement de la Douleur, Hôpital Ambroise Paré, Boulogne-Billancourt, France
| | - Ralf Baron
- Division of Neurological Pain Research and Therapy, Department of Neurology, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - David L Bennett
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Didier Bouhassira
- Inserm U987, Pathophysiology and Clinical Pharmacology of Pain, Centre d'évaluation et de Traitement de la Douleur, Hôpital Ambroise Paré, Boulogne-Billancourt, France
| | - Giorgio Cruccu
- Department of Human Neuroscience, University Sapienza, Rome, Italy
| | - Elon Eisenberg
- Faculty of Medicine, Technion, Israel Institute of Technology, Haifa, Israel
| | - Elena Enax-Krumova
- Department of Neurology, BG University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany
| | - Karen Deborah Davis
- Division of Brain, Imaging, and Behaviour, Krembil Brain Institute, Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | | | - Nanna B Finnerup
- Department of Clinical Medicine, Danish Pain Research Centre, Aarhus University, Aarhus, Denmark
| | - Luis Garcia-Larrea
- Central Integration of Pain (NeuroPain) Lab-Lyon Neuroscience Research Centre, INSERM U1028, CNRS, UMR5292, Université Claude Bernard, Bron, France
- Centre D'évaluation et de Traitement de la Douleur, Hôpital Neurologique, Lyon, France
| | - Ibrahem Hanafi
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Simon Haroutounian
- Division of Clinical and Translational Research, Department of Anesthesiology, Pain Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Pall Karlsson
- Department of Clinical Medicine, Danish Pain Research Centre, Aarhus University, Aarhus, Denmark
- Core Centre for Molecular Morphology, Section for Stereology and Microscopy, Aarhus University, Aarhus, Denmark
| | - Martin Rakusa
- Division of Neurology, University Medical Centre Maribor, Maribor, Slovenia
| | - Andrew S C Rice
- Pain Research, Department of Surgery and Cancer, Imperial College London, London, UK
| | - Juliane Sachau
- Division of Neurological Pain Research and Therapy, Department of Neurology, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Blair H Smith
- Division of Population Health and Genomics, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Claudia Sommer
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Thomas Tölle
- Department of Neurology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Josep Valls-Solé
- Institut d'Investigació Biomèdica August Pi i Sunyer, Barcelona, Spain
| | - Abirami Veluchamy
- Division of Population Health and Genomics, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
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10
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Schneider T, Filip J, Soares S, Sohns K, Carr R, Rukwied R, Schmelz M. Optimized Electrical Stimulation of C-Nociceptors in Humans Based on the Chronaxie of Porcine C-Fibers. THE JOURNAL OF PAIN 2023; 24:957-969. [PMID: 36681314 DOI: 10.1016/j.jpain.2023.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 12/21/2022] [Accepted: 01/10/2023] [Indexed: 01/20/2023]
Abstract
Classically, to electrically excite C-nociceptors, rectangular pulses are used with a duration close to the estimated chronaxie of C-fibres (about 2 ms). Recent results using slow depolarizing stimuli suggest longer chronaxies. We therefore set out to optimize C-fiber stimulation based on recordings of single C-nociceptors in-vivo and C-fiber compound-action-potentials (C-CAP) ex-vivo using half-sine shaped stimuli of durations between 1 and 250ms. Single fiber (n = 45) recording in pigs revealed high chronaxie values for C-touch fibers (15.8 ms), polymodal- (14.2 ms) and silent-nociceptors (16.8 ms). Activation thresholds decreased 2 to 3-fold in all fibre classes when increasing the duration of half-sine pulses from 1 to 25 ms (P < .05). C-CAPs strength-duration curves of the pig saphenous nerve (n = 7) showed the highest sensitivity for half-sine durations between 10 and 25 ms. Half-maximum currents for C-CAPS were reduced 3-fold compared to rectangular pulses (P < .01) whereas the opposite was found for A-fiber compound action potentials. Psychophysics in humans (n = 23) revealed that half-sine stimulus durations >10 ms reduced detection thresholds, pain thresholds, and stimulus current amplitudes required to generate a pain rating of 3 on an 11-point Numeric Rating Scale (NRS) as compared to 1 ms rectangular pulses (P < 0.05). Increasing the duration from 1 to 25 ms led to a 4-fold amplitude reduction for pain-thresholds and stimuli caused an axon-reflex flare. Excitability of single polymodal nociceptors in animals paralleled human psychophysics and we conclude optimized half-sine pulses facilitate C-nociceptor activation. PERSPECTIVE: Electrical stimulation with longer lasting half-sine wave pulses preferentially activates C-nociceptors and changes in the strength duration curve may identify nociceptor hyperexcitability in patients with neuropathic pain.
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Affiliation(s)
- Tobias Schneider
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany; Chronic Pain Unit, Department of Anesthesiology, University Hospital Basel, Basel, Switzerland.
| | - Julia Filip
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Sabrina Soares
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Kyra Sohns
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Richard Carr
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Roman Rukwied
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Martin Schmelz
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
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11
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Antunes FTT, Campos MM, Carvalho VDPR, da Silva Junior CA, Magno LAV, de Souza AH, Gomez MV. Current Drug Development Overview: Targeting Voltage-Gated Calcium Channels for the Treatment of Pain. Int J Mol Sci 2023; 24:ijms24119223. [PMID: 37298174 DOI: 10.3390/ijms24119223] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 04/29/2023] [Accepted: 05/02/2023] [Indexed: 06/12/2023] Open
Abstract
Voltage-gated calcium channels (VGCCs) are targeted to treat pain conditions. Since the discovery of their relation to pain processing control, they are investigated to find new strategies for better pain control. This review provides an overview of naturally based and synthetic VGCC blockers, highlighting new evidence on the development of drugs focusing on the VGCC subtypes as well as mixed targets with pre-clinical and clinical analgesic effects.
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Affiliation(s)
- Flavia Tasmin Techera Antunes
- Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 1N4, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Maria Martha Campos
- Programa de Pós-Graduação em Odontologia, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre 90619-900, RS, Brazil
| | | | | | - Luiz Alexandre Viana Magno
- Programa de Pós-Graduação em Ciências da Saúde, Faculdade Ciências Médicas de Minas Gerais (FCMMG), Belo Horizonte 30110-005, MG, Brazil
| | - Alessandra Hubner de Souza
- Programa de Pós-Graduação em Ciências da Saúde, Faculdade Ciências Médicas de Minas Gerais (FCMMG), Belo Horizonte 30110-005, MG, Brazil
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12
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Maximizing treatment efficacy through patient stratification in neuropathic pain trials. Nat Rev Neurol 2023; 19:53-64. [PMID: 36400867 DOI: 10.1038/s41582-022-00741-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2022] [Indexed: 11/19/2022]
Abstract
Treatment of neuropathic pain remains inadequate despite the elucidation of multiple pathophysiological mechanisms and the development of promising therapeutic compounds. The lack of success in translating knowledge into clinical practice has discouraged pharmaceutical companies from investing in pain medicine; however, new patient stratification approaches could help bridge the translation gap and develop individualized therapeutic approaches. As we highlight in this article, subgrouping of patients according to sensory profiles and other baseline characteristics could aid the prediction of treatment success. Furthermore, novel outcome measures have been developed for patients with neuropathic pain. The extent to which sensory profiles and outcome measures can be employed in routine clinical practice and clinical trials and across distinct neuropathic pain aetiologies is yet to be determined. Improvements in animal models, drawing on our knowledge of human pain, and robust public-private partnerships will be needed to pave the way to innovative and effective pain medicine in the future.
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13
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Sachau J, Baron R. Precision Medicine in Neuropathic Pain. Handb Exp Pharmacol 2023; 280:187-210. [PMID: 37439846 DOI: 10.1007/164_2023_662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Neuropathic pain is a common chronic pain condition that is caused by a lesion or disease of the somatosensory nervous system. The multitude of sensory negative and positive sensations and associated comorbidities have a major impact on quality of life of affected patients. Current treatment options often only lead to a partial pain relief or are even completely ineffective. In addition, many clinical trials for the development of new drugs have not met the primary endpoint. Therefore, there is still an unmet clinical need in neuropathic pain syndromes. One reason for this therapeutic dilemma could be the heterogeneity of neuropathic pain with a variety of pathophysiological pain mechanisms that are expressed differently in each patient regardless of the underlying disease etiology. Reclassification of neuropathic pain syndromes therefore focuses on the underlying mechanisms of pain development rather than the disease etiology. A priori stratification of patients based on these individual mechanisms could allow the identification of potential treatment responders and thus realize the concept of a mechanism-based treatment. As no biomarkers for pain mechanisms have been discovered yet, one has to rely on surrogate markers that are thought to be closely related to these mechanisms. In this chapter, we present promising predictive biomarkers, focusing in particular on sensory symptoms and signs assessed by patient-reported outcome measures and sensory testing, and discuss how these tools might be used in clinical trials in the future.
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Affiliation(s)
- Juliane Sachau
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany
| | - Ralf Baron
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany.
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14
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Abstract
Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.
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Affiliation(s)
- Qihua Fan
- Department of Neurology, Division of Neuromuscular Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - A Gordon Smith
- Department of Neurology, Division of Neuromuscular Medicine, Virginia Commonwealth University, Richmond, VA, USA
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15
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Arora V, Li T, Kumari S, Wang S, Asgar J, Chung MK. Capsaicin-induced depolymerization of axonal microtubules mediates analgesia for trigeminal neuropathic pain. Pain 2022; 163:1479-1488. [PMID: 34724681 PMCID: PMC9046530 DOI: 10.1097/j.pain.0000000000002529] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 10/05/2021] [Accepted: 10/25/2021] [Indexed: 11/26/2022]
Abstract
ABSTRACT Capsaicin is a specific agonist of transient receptor potential vanilloid 1 (TRPV1), which is enriched in nociceptors. Capsaicin not only produces acute pain but also leads to long-lasting analgesia in patients with chronic pain. Although capsaicin-induced TRPV1 and Ca 2+ /calpain-dependent ablation of axonal terminals is necessary for long-lasting analgesia, the mechanisms underlying capsaicin-induced ablation of axonal terminals and its association with analgesia are not fully understood. Microtubules are composed of tubulin polymers and serve as a main axonal cytoskeleton maintaining axonal integrity. In this study, we hypothesized that capsaicin would increase the depolymerization of microtubules and lead to axonal ablation and analgesia for trigeminal neuropathic pain. Paclitaxel, a microtubule stabilizer, decreased capsaicin-induced ablation of axonal terminals in time-lapsed imaging in vitro. Capsaicin increases free tubulin in dissociated sensory neurons, which was inhibited by paclitaxel. Consistently, subcutaneous injection of paclitaxel prevented capsaicin-induced axonal ablation in the hind paw skin. Capsaicin administration to the facial skin produced analgesia for mechanical hyperalgesia in mice with chronic constriction injury of the infraorbital nerve, which was prevented by the coadministration of paclitaxel and capsaicin. Whole-mount staining of facial skin showed that paclitaxel reduced capsaicin-induced ablation of peptidergic afferent terminals. Despite the suggested involvement of TRPV1 Ser801 phosphorylation on microtubule integrity, capsaicin-induced analgesia was not affected in TRPV1 S801A knock-in mice. In conclusion, capsaicin-induced depolymerization of axonal microtubules determined capsaicin-induced ablation of nociceptive terminals and the extent of analgesia. Further understanding of TRPV1/Ca 2+ -dependent mechanisms of capsaicin-induced ablation and analgesia may help to improve the management of chronic pain.
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Affiliation(s)
- Vipin Arora
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
| | - Tingting Li
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
| | - Sinu Kumari
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
| | - Sheng Wang
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
| | - Jamila Asgar
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
| | - Man-Kyo Chung
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, the University of Maryland Baltimore, Baltimore, MD, United States
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16
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Joksimovic SL, Jevtovic-Todorovic V, Todorovic SM. The role of voltage-gated calcium channels in the mechanisms of anesthesia and perioperative analgesia. Curr Opin Anaesthesiol 2022; 35:436-441. [PMID: 35787588 PMCID: PMC9616208 DOI: 10.1097/aco.0000000000001159] [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] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW A family of neuronal voltage-gated calcium channels (VGCCs) have received only recently a significant consideration regarding the mechanisms of anesthesia because VGCC inhibition may be important in anesthetic action by decreasing neuronal excitability and presynaptic excitatory transmission. The T-type VGCCs channels (T-channels), although rarely involved in synaptic neurotransmitter release, play an important role in controlling neuronal excitability and in generating spontaneous oscillatory bursting of groups of neurons in the thalamus thought to be involved in regulating the state of arousal and sleep. Furthermore, these channels are important regulators of neuronal excitability in pain pathway. This review will provide an overview of historic perspective and the recent literature on the role of VGCCs and T-channel inhibition in particular in the mechanisms of action of anesthetics and analgesics. RECENT FINDINGS Recent research in the field of novel mechanisms of hypnotic action of anesthetics revealed significant contribution of the Ca V 3.1 isoform of T-channels expressed in the thalamus. Furthermore, perioperative analgesia can be achieved by targeting Ca V 3.2 isoform of these channels that is abundantly expressed in pain pathways. SUMMARY The review summarizes current knowledge regarding the contribution of T-channels in hypnosis and analgesia. Further preclinical and clinical studies are needed to validate their potential for developing novel anesthetics and new perioperative pain therapies.
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Affiliation(s)
- Sonja L. Joksimovic
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Slobodan M. Todorovic
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
- Neuroscience Graduate Program, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
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17
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Gomez K, Tang C, Tan B, Perez-Miller S, Ran D, Loya S, Calderon-Rivera A, Stratton HJ, Duran P, Masterson KA, Gabrielsen AT, Alsbiei O, Dorame A, Serafini M, Moutal A, Wang J, Khanna R. Stereospecific Effects of Benzimidazolonepiperidine Compounds on T-Type Ca 2+ Channels and Pain. ACS Chem Neurosci 2022; 13:2035-2047. [PMID: 35671441 DOI: 10.1021/acschemneuro.2c00256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
T-type calcium channels activate in response to subthreshold membrane depolarizations and represent an important source of Ca2+ influx near the resting membrane potential. These channels regulate neuronal excitability and have been linked to pain. For this reason, T-type calcium channels are suitable molecular targets for the development of new non-opioid analgesics. Our previous work identified an analogue of benzimidazolonepiperidine, 5bk, that preferentially inhibited CaV3.2 channels and reversed mechanical allodynia. In this study, we synthesized and screened a small library of 47 compounds derived from 5bk. We found several compounds that inhibited the Ca2+ influx in DRG neurons of all sizes. After separating the enantiomers of each active compound, we found two compounds, 3-25-R and 3-14-3-S, that potently inhibited the Ca2+ influx. Whole-cell patch clamp recordings from small- to medium-sized DRG neurons revealed that both compounds decreased total Ca2+. Application of 3-14-3-S (but not 3-25-R) blocked transiently expressed CaV3.1-3.3 channels with a similar IC50 value. 3-14-3-S decreased T-type, but not N-type, Ca2+ currents in DRG neurons. Furthermore, intrathecal delivery of 3-14-3-S relieved tonic, neuropathic, and inflammatory pain in preclinical models. 3-14-3-S did not exhibit any activity against G protein-coupled opioid receptors. Preliminary docking studies also suggest that 3-14-3-S can bind to the central pore domain of T-type channels. Together, our chemical characterization and functional and behavioral data identify a novel T-type calcium channel blocker with in vivo efficacy in experimental models of tonic, neuropathic, and inflammatory pain.
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Affiliation(s)
- Kimberly Gomez
- Department of Molecular Pathobiology, College of Dentistry, New York University, 433 First Avenue, 8th Floor, New York, New York 10010, United States
| | - Cheng Tang
- Department of Molecular Pathobiology, College of Dentistry, New York University, 433 First Avenue, 8th Floor, New York, New York 10010, United States.,The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha 410081, China
| | - Bin Tan
- Department of Medicinal Chemistry, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, William Levine Hall, Room 320, 160 Frelinghuysen Road, Piscataway, New Jersey 0885, United States
| | - Samantha Perez-Miller
- Department of Molecular Pathobiology, College of Dentistry, New York University, 433 First Avenue, 8th Floor, New York, New York 10010, United States
| | - Dongzhi Ran
- School of Medicine, Department of Pharmacology and Physiology, Saint Louis University, 1402 S. Grand Blvd. Schwitalla Hall, Room 432, Saint Louis, Missouri 63104, United States
| | - Santiago Loya
- Department of Molecular Pathobiology, College of Dentistry, New York University, 433 First Avenue, 8th Floor, New York, New York 10010, United States
| | - Aida Calderon-Rivera
- Department of Molecular Pathobiology, College of Dentistry, New York University, 433 First Avenue, 8th Floor, New York, New York 10010, United States
| | - Harrison J Stratton
- School of Medicine, Department of Pharmacology and Physiology, Saint Louis University, 1402 S. Grand Blvd. Schwitalla Hall, Room 432, Saint Louis, Missouri 63104, United States
| | - Paz Duran
- Department of Molecular Pathobiology, College of Dentistry, New York University, 433 First Avenue, 8th Floor, New York, New York 10010, United States
| | - Kyleigh A Masterson
- School of Medicine, Department of Pharmacology and Physiology, Saint Louis University, 1402 S. Grand Blvd. Schwitalla Hall, Room 432, Saint Louis, Missouri 63104, United States
| | - Anna T Gabrielsen
- School of Medicine, Department of Pharmacology and Physiology, Saint Louis University, 1402 S. Grand Blvd. Schwitalla Hall, Room 432, Saint Louis, Missouri 63104, United States
| | - Omar Alsbiei
- School of Medicine, Department of Pharmacology and Physiology, Saint Louis University, 1402 S. Grand Blvd. Schwitalla Hall, Room 432, Saint Louis, Missouri 63104, United States
| | - Angie Dorame
- School of Medicine, Department of Pharmacology and Physiology, Saint Louis University, 1402 S. Grand Blvd. Schwitalla Hall, Room 432, Saint Louis, Missouri 63104, United States
| | - Maria Serafini
- School of Medicine, Department of Pharmacology and Physiology, Saint Louis University, 1402 S. Grand Blvd. Schwitalla Hall, Room 432, Saint Louis, Missouri 63104, United States
| | - Aubin Moutal
- School of Medicine, Department of Pharmacology and Physiology, Saint Louis University, 1402 S. Grand Blvd. Schwitalla Hall, Room 432, Saint Louis, Missouri 63104, United States
| | - Jun Wang
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona 85724, United States
| | - Rajesh Khanna
- Department of Molecular Pathobiology, College of Dentistry, New York University, 433 First Avenue, 8th Floor, New York, New York 10010, United States
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18
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Zhou X, Zhu Y, Wang Z, Lin Z, Zhu D, Xie C, Calcutt NA, Guan Y. Rate-Dependent Depression: A Predictor of the Therapeutic Efficacy in Treating Painful Diabetic Peripheral Neuropathy. Diabetes 2022; 71:1272-1281. [PMID: 35234842 DOI: 10.2337/db21-0960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 02/24/2022] [Indexed: 11/13/2022]
Abstract
We investigated the application of rate-dependent depression (RDD) of the Hoffmann (H) wave as a predictor of treatment efficacy in patients with painful diabetic peripheral neuropathy (DPN). General medical information, scales, and nerve conduction data were collected from 73 healthy subjects, 50 subjects with type 2 diabetes and painless DPN, and 71 subjects with type 2 diabetes and painful DPN. The left tibial nerve was stimulated, and RDD was calculated by the decline in amplitude of the third H wave relative to the first one. Gabapentin treatment was initiated after baseline evaluation, and the RDD and visual analog scale (VAS) score were both evaluated regularly during the 2-week study period. At baseline, the painful DPN group exhibited significant RDD impairment across all stimulation frequencies. Gabapentin treatment significantly reduced the VAS score and restored RDD during the 2-week observation period. RDD was found to be an independent factor of minimal VAS score improvement, such that the benefit increased by 1.27 times per 1% decrease in the RDD value. In conclusion, this study demonstrates that diabetes-induced loss of RDD can be modified by gabapentin and suggests that RDD may be valuable for predicting the initial efficacy of gabapentin therapy in patients with painful DPN.
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Affiliation(s)
- Xiajun Zhou
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Ying Zhu
- Department of Neurology, Shanghai International Medical Center, Shanghai, China
| | - Ze Wang
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Zhi Lin
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Desheng Zhu
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Chong Xie
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Nigel A Calcutt
- Department of Pathology, University of California, San Diego, San Diego, CA
| | - Yangtai Guan
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
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19
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Harding EK, Zamponi GW. Central and peripheral contributions of T-type calcium channels in pain. Mol Brain 2022; 15:39. [PMID: 35501819 PMCID: PMC9063214 DOI: 10.1186/s13041-022-00923-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 04/13/2022] [Indexed: 02/06/2023] Open
Abstract
AbstractChronic pain is a severely debilitating condition that reflects a long-term sensitization of signal transduction in the afferent pain pathway. Among the key players in this pathway are T-type calcium channels, in particular the Cav3.2 isoform. Because of their biophysical characteristics, these channels are ideally suited towards regulating neuronal excitability. Recent evidence suggests that T-type channels contribute to excitability of neurons all along the ascending and descending pain pathways, within primary afferent neurons, spinal dorsal horn neurons, and within pain-processing neurons in the midbrain and cortex. Here we review the contribution of T-type channels to neuronal excitability and function in each of these neuronal populations and how they are dysregulated in chronic pain conditions. Finally, we discuss their molecular pharmacology and the potential role of these channels as therapeutic targets for chronic pain.
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20
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Joksimovic SL, Jevtovic-Todorovic V, Todorovic SM. The Mechanisms of Plasticity of Nociceptive Ion Channels in Painful Diabetic Neuropathy. FRONTIERS IN PAIN RESEARCH 2022; 3:869735. [PMID: 35419564 PMCID: PMC8995507 DOI: 10.3389/fpain.2022.869735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 02/28/2022] [Indexed: 11/13/2022] Open
Abstract
Treating pain in patients suffering from small fiber neuropathies still represents a therapeutic challenge for health care providers and drug developers worldwide. Unfortunately, none of the currently available treatments can completely reverse symptoms of either gain or loss of peripheral nerve sensation. Therefore, there is a clear need for novel mechanism-based therapies for peripheral diabetic neuropathy (PDN) that would improve treatment of this serious condition. In this review, we summarize the current knowledge on the mechanisms and causes of peripheral sensory neurons damage in diabetes. In particular, we focused on the subsets of voltage-gated sodium channels, TRP family of ion channels and a CaV3.2 isoform of T-type voltage-gated calcium channels. However, even though their potential is well-validated in multiple rodent models of painful PDN, clinical trials with specific pharmacological blockers of these channels have failed to exhibit therapeutic efficacy. We argue that understanding the development of diabetes and causal relationship between hyperglycemia, glycosylation, and other post-translational modifications may lead to the development of novel therapeutics that would efficiently alleviate painful PDN by targeting disease-specific mechanisms rather than individual nociceptive ion channels.
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Affiliation(s)
- Sonja L Joksimovic
- Department of Anesthesiology, University of Colorado Denver, Aurora, CO, United States
| | | | - Slobodan M Todorovic
- Department of Anesthesiology, University of Colorado Denver, Aurora, CO, United States
- Neuroscience Graduate Program, University of Colorado Denver, Aurora, CO, United States
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21
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George DS, Hackelberg S, Jayaraj ND, Ren D, Edassery SL, Rathwell CA, Miller RE, Malfait AM, Savas JN, Miller RJ, Menichella DM. Mitochondrial calcium uniporter deletion prevents painful diabetic neuropathy by restoring mitochondrial morphology and dynamics. Pain 2022; 163:560-578. [PMID: 34232927 PMCID: PMC8720329 DOI: 10.1097/j.pain.0000000000002391] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 05/25/2021] [Accepted: 06/18/2021] [Indexed: 01/11/2023]
Abstract
ABSTRACT Painful diabetic neuropathy (PDN) is an intractable complication affecting 25% of diabetic patients. Painful diabetic neuropathy is characterized by neuropathic pain accompanied by dorsal root ganglion (DRG) nociceptor hyperexcitability, resulting in calcium overload, axonal degeneration, and loss of cutaneous innervation. The molecular pathways underlying these effects are unknown. Using high-throughput and deep-proteome profiling, we found that mitochondrial fission proteins were elevated in DRG neurons from mice with PDN induced by a high-fat diet (HFD). In vivo calcium imaging revealed increased calcium signaling in DRG nociceptors from mice with PDN. Furthermore, using electron microscopy, we showed that mitochondria in DRG nociceptors had fragmented morphology as early as 2 weeks after starting HFD, preceding the onset of mechanical allodynia and small-fiber degeneration. Moreover, preventing calcium entry into the mitochondria, by selectively deleting the mitochondrial calcium uniporter from these neurons, restored normal mitochondrial morphology, prevented axonal degeneration, and reversed mechanical allodynia in the HFD mouse model of PDN. These studies suggest a molecular cascade linking neuropathic pain to axonal degeneration in PDN. In particular, nociceptor hyperexcitability and the associated increased intracellular calcium concentrations could lead to excessive calcium entry into mitochondria mediated by the mitochondrial calcium uniporter, resulting in increased calcium-dependent mitochondrial fission and ultimately contributing to small-fiber degeneration and neuropathic pain in PDN. Hence, we propose that targeting calcium entry into nociceptor mitochondria may represent a promising effective and disease-modifying therapeutic approach for this currently intractable and widespread affliction. Moreover, these results are likely to inform studies of other neurodegenerative disease involving similar underlying events.
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Affiliation(s)
| | | | | | - Dongjun Ren
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | | | - Craig A. Rathwell
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Rachel E. Miller
- Department of Internal Medicine, Rush Medical College, Chicago, IL, United States
| | - Anne-Marie Malfait
- Department of Internal Medicine, Rush Medical College, Chicago, IL, United States
| | | | - Richard J. Miller
- Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
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22
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Voltage-dependent Ca V3.2 and Ca V2.2 channels in nociceptive pathways. Pflugers Arch 2022; 474:421-434. [PMID: 35043234 DOI: 10.1007/s00424-022-02666-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 10/19/2022]
Abstract
Noxious stimuli like cold, heat, pH change, tissue damage, and inflammation depolarize a membrane of peripheral endings of specialized nociceptive neurons which eventually results in the generation of an action potential. The electrical signal is carried along a long axon of nociceptive neurons from peripheral organs to soma located in dorsal root ganglions and further to the dorsal horn of the spinal cord where it is transmitted through a chemical synapse and is carried through the spinal thalamic tract into the brain. Two subtypes of voltage-activated calcium play a major role in signal transmission: a low voltage-activated CaV3.2 channel and a high voltage-activated CaV2.2 channel. The CaV3.2 channel contributes mainly to the signal conductance along nociceptive neurons while the principal role of the CaV2.2 channel is in the synaptic transmission at the dorsal horn. Both channels contribute to the signal initiation at peripheral nerve endings. This review summarizes current knowledge about the expression and distribution of these channels in a nociceptive pathway, the regulation of their expression and gating during pain pathology, and their suitability as targets for pharmacological therapy.
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23
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Fan Q, Gordon Smith A. Recent updates in the treatment of diabetic polyneuropathy. Fac Rev 2022. [PMID: 36311537 DOI: 10.1270/r/11-30] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023] Open
Abstract
Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.
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Affiliation(s)
- Qihua Fan
- Department of Neurology, Division of Neuromuscular Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - A Gordon Smith
- Department of Neurology, Division of Neuromuscular Medicine, Virginia Commonwealth University, Richmond, VA, USA
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24
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Sloan G, Alam U, Selvarajah D, Tesfaye S. The Treatment of Painful Diabetic Neuropathy. Curr Diabetes Rev 2022; 18:e070721194556. [PMID: 34238163 DOI: 10.2174/1573399817666210707112413] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 02/18/2021] [Accepted: 03/08/2021] [Indexed: 11/22/2022]
Abstract
Painful diabetic peripheral neuropathy (painful-DPN) is a highly prevalent and disabling condition, affecting up to one-third of patients with diabetes. This condition can have a profound impact resulting in a poor quality of life, disruption of employment, impaired sleep, and poor mental health with an excess of depression and anxiety. The management of painful-DPN poses a great challenge. Unfortunately, currently there are no Food and Drug Administration (USA) approved disease-modifying treatments for diabetic peripheral neuropathy (DPN) as trials of putative pathogenetic treatments have failed at phase 3 clinical trial stage. Therefore, the focus of managing painful- DPN other than improving glycaemic control and cardiovascular risk factor modification is treating symptoms. The recommended treatments based on expert international consensus for painful- DPN have remained essentially unchanged for the last decade. Both the serotonin re-uptake inhibitor (SNRI) duloxetine and α2δ ligand pregabalin have the most robust evidence for treating painful-DPN. The weak opioids (e.g. tapentadol and tramadol, both of which have an SNRI effect), tricyclic antidepressants such as amitriptyline and α2δ ligand gabapentin are also widely recommended and prescribed agents. Opioids (except tramadol and tapentadol), should be prescribed with caution in view of the lack of definitive data surrounding efficacy, concerns surrounding addiction and adverse events. Recently, emerging therapies have gained local licenses, including the α2δ ligand mirogabalin (Japan) and the high dose 8% capsaicin patch (FDA and Europe). The management of refractory painful-DPN is difficult; specialist pain services may offer off-label therapies (e.g. botulinum toxin, intravenous lidocaine and spinal cord stimulation), although there is limited clinical trial evidence supporting their use. Additionally, despite combination therapy being commonly used clinically, there is little evidence supporting this practise. There is a need for further clinical trials to assess novel therapeutic agents, optimal combination therapy and existing agents to determine which are the most effective for the treatment of painful-DPN. This article reviews the evidence for the treatment of painful-DPN, including emerging treatment strategies such as novel compounds and stratification of patients according to individual characteristics (e.g. pain phenotype, neuroimaging and genotype) to improve treatment responses.
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Affiliation(s)
- Gordon Sloan
- Diabetes Research Unit, Royal Hallamshire Hospital, Sheffield Teaching Hospitals, NHS Foundation Trust, Sheffield, UK
| | - Uazman Alam
- Department of Cardiovascular and Metabolic Medicine and the Pain Research Institute, Institute of Life Course and Medical Sciences, University of Liverpool, and Liverpool University Hospital, NHS Foundation Trust, Liverpool, UK
- Division of Diabetes, Endocrinology and Gastroenterology, Institute of Human Development, University of Manchester, Manchester, UK
| | - Dinesh Selvarajah
- Diabetes Research Unit, Royal Hallamshire Hospital, Sheffield Teaching Hospitals, NHS Foundation Trust, Sheffield, UK
- Department of Oncology and Human Metabolism, University of Sheffield, Sheffield, UK
| | - Solomon Tesfaye
- Diabetes Research Unit, Royal Hallamshire Hospital, Sheffield Teaching Hospitals, NHS Foundation Trust, Sheffield, UK
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25
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Stucky CL, Mikesell AR. Cutaneous pain in disorders affecting peripheral nerves. Neurosci Lett 2021; 765:136233. [PMID: 34506882 PMCID: PMC8579816 DOI: 10.1016/j.neulet.2021.136233] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 08/16/2021] [Accepted: 09/02/2021] [Indexed: 02/08/2023]
Abstract
Our ability to quickly detect and respond to harmful environmental stimuli is vital for our safety and survival. This inherent acute pain detection is a "gift" because it both protects our body from harm and allows healing of damaged tissues [1]. Damage to tissues from trauma or disease can result in distorted or amplified nociceptor signaling and sensitization of the spinal cord and brain (Central Nervous System; CNS) pathways to normal input from light touch mechanoreceptors. Together, these processes can result in nagging to unbearable chronic pain and extreme sensitivity to light skin touch (allodynia). Unlike acute protective pain, chronic pain and allodynia serve no useful purpose and can severely reduce the quality of life of an affected person. Chronic pain can arise from impairment to peripheral neurons, a phenomenon called "peripheral neuropathic pain." Peripheral neuropathic pain can be caused by many insults that directly affect peripheral sensory neurons, including mechanical trauma, metabolic imbalance (e.g., diabetes), autoimmune diseases, chemotherapeutic agents, viral infections (e.g., shingles). These insults cause "acquired" neuropathies such as small-fiber neuropathies, diabetic neuropathy, chemotherapy-induced peripheral neuropathy, and post herpetic neuralgia. Peripheral neuropathic pain can also be caused by genetic factors and result in hereditary neuropathies that include Charcot-Marie-Tooth disease, rare channelopathies and Fabry disease. Many acquired and hereditary neuropathies affect the skin, our largest organ and protector of nearly our entire body. Here we review how cutaneous nociception (pain perceived from the skin) is altered following diseases that affect peripheral nerves that innervate the skin. We provide an overview of how noxious stimuli are detected and encoded by molecular transducers on subtypes of cutaneous afferent endings and conveyed to the CNS. Next, we discuss several acquired and hereditary diseases and disorders that cause painful or insensate (lack of sensation) cutaneous peripheral neuropathies, the symptoms and percepts patients experience, and how cutaneous afferents and other peripheral cell types are altered in function in these disorders. We highlight exciting new research areas that implicate non-neuronal skin cells, particularly keratinocytes, in cutaneous nociception and peripheral neuropathies. Finally, we conclude with ideas for innovative new directions, areas of unmet need, and potential opportunities for novel cutaneous therapeutics that may avoid CNS side effects, as well as ideas for improved translation of mechanisms identified in preclinical models to patients.
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Affiliation(s)
- Cheryl L Stucky
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States.
| | - Alexander R Mikesell
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
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26
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Worthington A, Kalteniece A, Ferdousi M, D'Onofrio L, Dhage S, Azmi S, Adamson C, Hamdy S, Malik RA, Calcutt NA, Marshall AG. Spinal Inhibitory Dysfunction in Patients With Painful or Painless Diabetic Neuropathy. Diabetes Care 2021; 44:1835-1841. [PMID: 34385346 DOI: 10.2337/dc20-2797] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 05/13/2021] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Impaired rate-dependent depression of the Hoffman reflex (HRDD) is a marker of spinal inhibitory dysfunction and has previously been associated with painful neuropathy in a proof-of-concept study in patients with type 1 diabetes. We have now undertaken an assessment of HRDD in patients with type 1 or type 2 diabetes. RESEARCH DESIGN AND METHODS A total of 148 participants, including 34 healthy control subjects, 42 patients with painful diabetic neuropathy, and 62 patients with diabetic neuropathy without pain, underwent an assessment of HRDD and a detailed assessment of peripheral neuropathy, including nerve conduction studies, corneal confocal microscopy, and thermal threshold testing. RESULTS Compared with healthy control subjects (P < 0.001) and patients without pain (P < 0.001), we found that HRDD is impaired in patients with type 1 or type 2 diabetes with neuropathic pain. These impairments are unrelated to diabetes type and the presence or severity of neuropathy. In contrast, patients without neuropathic pain (P < 0.05) exhibited enhanced HRDD compared with control subjects. CONCLUSIONS We suggest that loss or impairment of HRDD may help to identify a subpopulation of patients with painful diabetic neuropathy mediated by impaired spinal inhibitory systems who may respond optimally to therapies that target spinal or supraspinal mechanisms. Enhanced RDD in patients without pain may reflect engagement of spinal pain-suppressing mechanisms.
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Affiliation(s)
- Anne Worthington
- Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Alise Kalteniece
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Maryam Ferdousi
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Luca D'Onofrio
- Department of Experimental Medicine, Sapienza University, Rome, Italy
| | - Shaishav Dhage
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Shazli Azmi
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K.,Diabetes Centre, Manchester University NHS Foundation Trust, Manchester, U.K
| | - Clare Adamson
- Diabetes Centre, Manchester University NHS Foundation Trust, Manchester, U.K
| | - Shaheen Hamdy
- Centre for Gastrointestinal Sciences, Division of Diabetes and Endocrinology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Rayaz A Malik
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K.,Weill Cornell Medicine-Qatar, Research Division, Qatar Foundation, Education City
| | - Nigel A Calcutt
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Andrew G Marshall
- Division of Neuroscience and Experimental Psychology, Faculty of Medical and Human Sciences, University of Manchester, Manchester, U.K. .,Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, U.K
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Middleton SJ, Barry AM, Comini M, Li Y, Ray PR, Shiers S, Themistocleous AC, Uhelski ML, Yang X, Dougherty PM, Price TJ, Bennett DL. Studying human nociceptors: from fundamentals to clinic. Brain 2021; 144:1312-1335. [PMID: 34128530 PMCID: PMC8219361 DOI: 10.1093/brain/awab048] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 11/26/2020] [Accepted: 12/08/2020] [Indexed: 12/14/2022] Open
Abstract
Chronic pain affects one in five of the general population and is the third most important cause of disability-adjusted life-years globally. Unfortunately, treatment remains inadequate due to poor efficacy and tolerability. There has been a failure in translating promising preclinical drug targets into clinic use. This reflects challenges across the whole drug development pathway, from preclinical models to trial design. Nociceptors remain an attractive therapeutic target: their sensitization makes an important contribution to many chronic pain states, they are located outside the blood-brain barrier, and they are relatively specific. The past decade has seen significant advances in the techniques available to study human nociceptors, including: the use of corneal confocal microscopy and biopsy samples to observe nociceptor morphology, the culture of human nociceptors (either from surgical or post-mortem tissue or using human induced pluripotent stem cell derived nociceptors), the application of high throughput technologies such as transcriptomics, the in vitro and in vivo electrophysiological characterization through microneurography, and the correlation with pain percepts provided by quantitative sensory testing. Genome editing in human induced pluripotent stem cell-derived nociceptors enables the interrogation of the causal role of genes in the regulation of nociceptor function. Both human and rodent nociceptors are more heterogeneous at a molecular level than previously appreciated, and while we find that there are broad similarities between human and rodent nociceptors there are also important differences involving ion channel function, expression, and cellular excitability. These technological advances have emphasized the maladaptive plastic changes occurring in human nociceptors following injury that contribute to chronic pain. Studying human nociceptors has revealed new therapeutic targets for the suppression of chronic pain and enhanced repair. Cellular models of human nociceptors have enabled the screening of small molecule and gene therapy approaches on nociceptor function, and in some cases have enabled correlation with clinical outcomes. Undoubtedly, challenges remain. Many of these techniques are difficult to implement at scale, current induced pluripotent stem cell differentiation protocols do not generate the full diversity of nociceptor populations, and we still have a relatively poor understanding of inter-individual variation in nociceptors due to factors such as age, sex, or ethnicity. We hope our ability to directly investigate human nociceptors will not only aid our understanding of the fundamental neurobiology underlying acute and chronic pain but also help bridge the translational gap.
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Affiliation(s)
- Steven J Middleton
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Allison M Barry
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Maddalena Comini
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Yan Li
- Department of Anesthesia and Pain Medicine, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Pradipta R Ray
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Stephanie Shiers
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Andreas C Themistocleous
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.,Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2000, South Africa
| | - Megan L Uhelski
- Department of Anesthesia and Pain Medicine, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Xun Yang
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Patrick M Dougherty
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2000, South Africa
| | - Theodore J Price
- Department of Neuroscience and Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX 75080, USA
| | - David L Bennett
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
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28
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Harding EK, Dedek A, Bonin RP, Salter MW, Snutch TP, Hildebrand ME. The T-type calcium channel antagonist, Z944, reduces spinal excitability and pain hypersensitivity. Br J Pharmacol 2021; 178:3517-3532. [PMID: 33871884 PMCID: PMC8453510 DOI: 10.1111/bph.15498] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 03/02/2021] [Accepted: 04/05/2021] [Indexed: 11/29/2022] Open
Abstract
Background and Purpose T‐type voltage‐gated calcium channels are an emerging therapeutic target for neurological disorders including epilepsy and pain. Inhibition of T‐type channels reduces the excitability of peripheral nociceptive sensory neurons and reverses pain hypersensitivity in male rodent pain models. However, administration of peripherally restricted T‐type antagonists failed to show efficacy in multiple clinical and preclinical pain trials, suggesting that inhibition of peripheral T‐type channels alone may be insufficient for pain relief. Experimental Approach We utilized the selective and CNS‐penetrant T‐type channel antagonist, Z944, in electrophysiological, calcium imaging and behavioural paradigms to determine its effect on lamina I neuron excitability and inflammatory pain behaviours. Key Results Voltage‐clamp recordings from lamina I spinal neurons of adult rats revealed that approximately 80% of neurons possess a low threshold T‐type current, which was blocked by Z944. Due to this highly prevalent T‐type current, Z944 potently blocked action‐potential evoked somatic and dendritic calcium transients in lamina I neurons. Moreover, application of Z944 to spinal cord slices attenuated action potential firing rates in over half of laminae I/II neurons. Finally, we found that intraperitoneal injection of Z944 (1–10 mg·kg−1) dose‐dependently reversed mechanical allodynia in the complete Freund's adjuvant model of persistent inflammatory pain, with a similar magnitude and time course of analgesic effects between male and female rats. Conclusion and Implications T‐type calcium channels critically shape the excitability of lamina I pain processing neurons and inhibition of these channels by the clinical stage antagonist Z944 potently reverses pain hypersensitivity across sexes.
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Affiliation(s)
- Erika K Harding
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.,Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Annemarie Dedek
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada.,Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Robert P Bonin
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.,University of Toronto Centre for the Study of Pain, University of Toronto, Toronto, Ontario, Canada
| | - Michael W Salter
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Terrance P Snutch
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada.,Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michael E Hildebrand
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada.,Neuroscience Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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29
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Marshall A, Alam U, Themistocleous A, Calcutt N, Marshall A. Novel and Emerging Electrophysiological Biomarkers of Diabetic Neuropathy and Painful Diabetic Neuropathy. Clin Ther 2021; 43:1441-1456. [PMID: 33906790 DOI: 10.1016/j.clinthera.2021.03.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 03/26/2021] [Accepted: 03/27/2021] [Indexed: 12/14/2022]
Abstract
PURPOSE Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes. Small and large peripheral nerve fibers can be involved in DPN. Large nerve fiber damage causes paresthesia, sensory loss, and muscle weakness, and small nerve fiber damage is associated with pain, anesthesia, foot ulcer, and autonomic symptoms. Treatments for DPN and painful DPN (pDPN) pose considerable challenges due to the lack of effective therapies. To meet these challenges, there is a major need to develop biomarkers that can reliably diagnose and monitor progression of nerve damage and, for pDPN, facilitate personalized treatment based on underlying pain mechanisms. METHODS This study involved a comprehensive literature review, incorporating article searches in electronic databases (Google Scholar, PubMed, and OVID) and reference lists of relevant articles with the authors' substantial expertise in DPN. This review considered seminal and novel research and summarizes emerging biomarkers of DPN and pDPN that are based on neurophysiological methods. FINDINGS From the evidence gathered from 145 papers, this submission describes emerging clinical neurophysiological methods with potential to act as biomarkers for the diagnosis and monitoring of DPN as well as putative future roles as predictors of response to antineuropathic pain medication in pDPN. Nerve conduction studies only detect large fiber damage and do not capture pathology or dysfunction of small fibers. Because small nerve fiber damage is prominent in DPN, additional biomarkers of small nerve fiber function are needed. Activation of peripheral nociceptor fibers using laser, heat, or targeted electrical stimuli can generate pain-related evoked potentials, which are an objective neurophysiological measure of damage along the small fiber pathways. Assessment of nerve excitability, which provides a surrogate of axonal properties, may detect alterations in function before abnormalities are detected by nerve conduction studies. Microneurography and rate-dependent depression of the Hoffmann-reflex can be used to dissect underlying pain-generating mechanisms arising from the periphery and spinal cord, respectively. Their role in informing mechanistic-based treatment of pDPN as well as facilitating clinical trials design is discussed. IMPLICATIONS The neurophysiological methods discussed, although currently not practical for use in busy outpatient settings, detect small fiber and early large fiber damage in DPN as well as disclosing dominant pain mechanisms in pDPN. They are suited as diagnostic and predictive biomarkers as well as end points in mechanistic clinical trials of DPN and pDPN.
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Affiliation(s)
- Anne Marshall
- Musculoskeletal Biology, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom; Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Uazman Alam
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom; Cardiovascular and Metabolic Medicine, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Andreas Themistocleous
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Nigel Calcutt
- Department of Pathology, University of California, San Diego, La Jolla, California
| | - Andrew Marshall
- Musculoskeletal Biology, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom; Department of Clinical Neurophysiology, The Walton Centre, Liverpool, United Kingdom; Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom.
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30
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Abstract
Neuropathy is a common complication of long-term diabetes that impairs quality of life by producing pain, sensory loss and limb amputation. The presence of neuropathy in both insulin-deficient (type 1) and insulin resistant (type 2) diabetes along with the slowing of progression of neuropathy by improved glycemic control in type 1 diabetes has caused the majority of preclinical and clinical investigations to focus on hyperglycemia as the initiating pathogenic lesion. Studies in animal models of diabetes have identified multiple plausible mechanisms of glucotoxicity to the nervous system including post-translational modification of proteins by glucose and increased glucose metabolism by aldose reductase, glycolysis and other catabolic pathways. However, it is becoming increasingly apparent that factors not necessarily downstream of hyperglycemia can also contribute to the incidence, progression and severity of neuropathy and neuropathic pain. For example, peripheral nerve contains insulin receptors that transduce the neurotrophic and neurosupportive properties of insulin, independent of systemic glucose regulation, while the detection of neuropathy and neuropathic pain in patients with metabolic syndrome and failure of improved glycemic control to protect against neuropathy in cohorts of type 2 diabetic patients has placed a focus on the pathogenic role of dyslipidemia. This review provides an overview of current understanding of potential initiating lesions for diabetic neuropathy and the multiple downstream mechanisms identified in cell and animal models of diabetes that may contribute to the pathogenesis of diabetic neuropathy and neuropathic pain.
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31
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Lee-Kubli CA, Zhou X, Jolivalt CG, Calcutt NA. Pharmacological Modulation of Rate-Dependent Depression of the Spinal H-Reflex Predicts Therapeutic Efficacy against Painful Diabetic Neuropathy. Diagnostics (Basel) 2021; 11:diagnostics11020283. [PMID: 33670344 PMCID: PMC7917809 DOI: 10.3390/diagnostics11020283] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 12/22/2022] Open
Abstract
Impaired rate-dependent depression (RDD) of the spinal H-reflex occurs in diabetic rodents and a sub-set of patients with painful diabetic neuropathy. RDD is unaffected in animal models of painful neuropathy associated with peripheral pain mechanisms and diabetic patients with painless neuropathy, suggesting RDD could serve as a biomarker for individuals in whom spinal disinhibition contributes to painful neuropathy and help identify therapies that target impaired spinal inhibitory function. The spinal pharmacology of RDD was investigated in normal rats and rats after 4 and 8 weeks of streptozotocin-induced diabetes. In normal rats, dependence of RDD on spinal GABAergic inhibitory function encompassed both GABAA and GABAB receptor sub-types. The time-dependent emergence of impaired RDD in diabetic rats was preceded by depletion of potassium-chloride co-transporter 2 (KCC2) protein in the dorsal, but not ventral, spinal cord and by dysfunction of GABAA receptor-mediated inhibition. GABAB receptor-mediated spinal inhibition remained functional and initially compensated for loss of GABAA receptor-mediated inhibition. Administration of the GABAB receptor agonist baclofen restored RDD and alleviated indices of neuropathic pain in diabetic rats, as did spinal delivery of the carbonic anhydrase inhibitor acetazolamide. Pharmacological manipulation of RDD can be used to identify potential therapies that act against neuropathic pain arising from spinal disinhibition.
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32
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Early Detection of Diabetic Peripheral Neuropathy: A Focus on Small Nerve Fibres. Diagnostics (Basel) 2021; 11:diagnostics11020165. [PMID: 33498918 PMCID: PMC7911433 DOI: 10.3390/diagnostics11020165] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/14/2021] [Accepted: 01/20/2021] [Indexed: 02/07/2023] Open
Abstract
Diabetic peripheral neuropathy (DPN) is the most common complication of both type 1 and 2 diabetes. As a result, neuropathic pain, diabetic foot ulcers and lower-limb amputations impact drastically on quality of life, contributing to the individual, societal, financial and healthcare burden of diabetes. DPN is diagnosed at a late, often pre-ulcerative stage due to a lack of early systematic screening and the endorsement of monofilament testing which identifies advanced neuropathy only. Compared to the success of the diabetic eye and kidney screening programmes there is clearly an unmet need for an objective reliable biomarker for the detection of early DPN. This article critically appraises research and clinical methods for the diagnosis or screening of early DPN. In brief, functional measures are subjective and are difficult to implement due to technical complexity. Moreover, skin biopsy is invasive, expensive and lacks diagnostic laboratory capacity. Indeed, point-of-care nerve conduction tests are convenient and easy to implement however questions are raised regarding their suitability for use in screening due to the lack of small nerve fibre evaluation. Corneal confocal microscopy (CCM) is a rapid, non-invasive, and reproducible technique to quantify small nerve fibre damage and repair which can be conducted alongside retinopathy screening. CCM identifies early sub-clinical DPN, predicts the development and allows staging of DPN severity. Automated quantification of CCM with AI has enabled enhanced unbiased quantification of small nerve fibres and potentially early diagnosis of DPN. Improved screening tools will prevent and reduce the burden of foot ulceration and amputations with the primary aim of reducing the prevalence of this common microvascular complication.
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33
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Jin HY, Moon SS, Calcutt NA. Lost in Translation? Measuring Diabetic Neuropathy in Humans and Animals. Diabetes Metab J 2021; 45:27-42. [PMID: 33307618 PMCID: PMC7850880 DOI: 10.4093/dmj.2020.0216] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/06/2020] [Indexed: 12/21/2022] Open
Abstract
The worldwide diabetes epidemic is estimated to currently afflict almost 500 million persons. Long-term diabetes damages multiple organ systems with the blood vessels, eyes, kidneys and nervous systems being particularly vulnerable. These complications of diabetes reduce lifespan, impede quality of life and impose a huge social and economic burden on both the individual and society. Peripheral neuropathy is a debilitating complication that will impact over half of all persons with diabetes. There is no treatment for diabetic neuropathy and a disturbingly long history of therapeutic approaches showing promise in preclinical studies but failing to translate to the clinic. These failures have prompted re-examination of both the animal models and clinical trial design. This review focuses on the functional and structural parameters used as indices of peripheral neuropathy in preclinical and clinical studies and the extent to which they share a common pathogenesis and presentation. Nerve conduction studies in large myelinated fibers have long been the mainstay of preclinical efficacy screening programs and clinical trials, supplemented by quantitative sensory tests. However, a more refined approach is emerging that incorporates measures of small fiber density in the skin and cornea alongside these traditional assays at both preclinical and clinical phases.
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Affiliation(s)
- Heung Yong Jin
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Jeonbuk National University Medical School, Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju,
USA
| | - Seong-Su Moon
- Department of Internal Medicine, Dongguk University College of Medicine, Gyeongju,
USA
- Division of Endocrinology, Department of Internal Medicine, Nazareth General Hospital, Daegu,
Korea,
USA
| | - Nigel A. Calcutt
- Department of Pathology, University of California San Diego, La Jolla, CA,
USA
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34
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Davis KD, Aghaeepour N, Ahn AH, Angst MS, Borsook D, Brenton A, Burczynski ME, Crean C, Edwards R, Gaudilliere B, Hergenroeder GW, Iadarola MJ, Iyengar S, Jiang Y, Kong JT, Mackey S, Saab CY, Sang CN, Scholz J, Segerdahl M, Tracey I, Veasley C, Wang J, Wager TD, Wasan AD, Pelleymounter MA. Discovery and validation of biomarkers to aid the development of safe and effective pain therapeutics: challenges and opportunities. Nat Rev Neurol 2020; 16:381-400. [PMID: 32541893 PMCID: PMC7326705 DOI: 10.1038/s41582-020-0362-2] [Citation(s) in RCA: 211] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2020] [Indexed: 02/06/2023]
Abstract
Pain medication plays an important role in the treatment of acute and chronic pain conditions, but some drugs, opioids in particular, have been overprescribed or prescribed without adequate safeguards, leading to an alarming rise in medication-related overdose deaths. The NIH Helping to End Addiction Long-term (HEAL) Initiative is a trans-agency effort to provide scientific solutions to stem the opioid crisis. One component of the initiative is to support biomarker discovery and rigorous validation in collaboration with industry leaders to accelerate high-quality clinical research into neurotherapeutics and pain. The use of objective biomarkers and clinical trial end points throughout the drug discovery and development process is crucial to help define pathophysiological subsets of pain, evaluate target engagement of new drugs and predict the analgesic efficacy of new drugs. In 2018, the NIH-led Discovery and Validation of Biomarkers to Develop Non-Addictive Therapeutics for Pain workshop convened scientific leaders from academia, industry, government and patient advocacy groups to discuss progress, challenges, gaps and ideas to facilitate the development of biomarkers and end points for pain. The outcomes of this workshop are outlined in this Consensus Statement.
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Affiliation(s)
- Karen D Davis
- Department of Surgery and Institute of Medical Science, University of Toronto, Toronto, ON, Canada.
- Division of Brain, Imaging and Behaviour, Krembil Brain Institute, Toronto Western Hospital, University Health Network, Toronto, ON, Canada.
| | - Nima Aghaeepour
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Martin S Angst
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - David Borsook
- Center for Pain and the Brain, Harvard Medical School, Boston, MA, USA
| | | | | | | | - Robert Edwards
- Pain Management Center, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Brice Gaudilliere
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Georgene W Hergenroeder
- The Vivian L. Smith Department of Neurosurgery, The University of Texas Health Science Center at Houston, McGovern Medical School, Houston, TX, USA
| | - Michael J Iadarola
- Department of Perioperative Medicine, Clinical Center, NIH, Rockville, MD, USA
| | - Smriti Iyengar
- Division of Translational Research, National Institute of Neurological Disorders and Stroke, NIH, Rockville, MD, USA
| | - Yunyun Jiang
- The Biostatistics Center, Milken Institute School of Public Health, The George Washington University, Washington, DC, USA
| | - Jiang-Ti Kong
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Sean Mackey
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Carl Y Saab
- Department of Neuroscience and Department of Neurosurgery, Carney Institute for Brain Science, Brown University, Providence, RI, USA
| | - Christine N Sang
- Department of Anesthesiology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Joachim Scholz
- Neurocognitive Disorders, Pain and New Indications, Biogen, Cambridge, MA, USA
| | | | - Irene Tracey
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | | | - Jing Wang
- Department of Anesthesiology, Perioperative Care and Pain Medicine, NYU School of Medicine, New York, NY, USA
| | - Tor D Wager
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH, USA
| | - Ajay D Wasan
- Anesthesiology and Perioperative Medicine and Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mary Ann Pelleymounter
- Division of Translational Research, National Institute of Neurological Disorders and Stroke, NIH, Rockville, MD, USA
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Langeslag M, Kress M. The ceramide-S1P pathway as a druggable target to alleviate peripheral neuropathic pain. Expert Opin Ther Targets 2020; 24:869-884. [PMID: 32589067 DOI: 10.1080/14728222.2020.1787989] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Introduction: Neuropathic pain disorders are diverse, and the currently available therapies are ineffective in the majority of cases. Therefore, there is a major need for gaining novel mechanistic insights and developing new treatment strategies for neuropathic pain. Areas covered: We performed an in-depth literature search on the molecular mechanisms and systemic importance of the ceramide-to-S1P rheostat regulating neuron function and neuroimmune interactions in the development of neuropathic pain. Expert opinion: The S1P receptor modulator FTY720 (fingolimod, Gilenya®), LPA receptor antagonists and several mechanistically related compounds in clinical development raise great expectations for treating neuropathic pain disorders. Research on S1P receptors, S1P receptor modulators or SPHK inhibitors with distinct selectivity, pharmacokinetics and safety must provide more mechanistic insight into whether they may qualify as useful treatment options for neuropathic pain disorders. The functional relevance of genetic variations within the ceramide-to-S1P rheostat should be explored for an enhanced understanding of neuropathic pain pathogenesis. The ceramide-to-S1P rheostat is emerging as a critically important regulator hub of neuroimmune interactions along the pain pathway, and improved mechanistic insight is required to develop more precise and effective drug treatment options for patients suffering from neuropathic pain disorders.
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Affiliation(s)
- Michiel Langeslag
- Institute of Physiology, DPMP, Medical University Innsbruck , Austria
| | - Michaela Kress
- Institute of Physiology, DPMP, Medical University Innsbruck , Austria
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Slow depolarizing stimuli differentially activate mechanosensitive and silent C nociceptors in human and pig skin. Pain 2020; 161:2119-2128. [DOI: 10.1097/j.pain.0000000000001912] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 04/08/2020] [Indexed: 01/10/2023]
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Malik RA. Diabetic neuropathy: A focus on small fibres. Diabetes Metab Res Rev 2020; 36 Suppl 1:e3255. [PMID: 31828951 DOI: 10.1002/dmrr.3255] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 11/25/2019] [Indexed: 01/16/2023]
Abstract
Diabetic peripheral neuropathy (DPN) is diagnosed too late, which contrasts with our approach for diabetic retinopathy and nephropathy, where incipient disease is detected early enabling timely treatment. The 10-g monofilament and a foot exam are the commonly used methods for screening diabetic neuropathy, but this primarily identifies moderate to severe diabetic neuropathy. Small fibres are damaged early and are associated with the development of painful diabetic neuropathy, foot ulceration, and Charcot foot. Tests of small fibre damage include thermal thresholds, microneurography, evoked potentials, sudomotor function, laser Doppler flare, skin biopsy, and corneal confocal microscopy. Measures of small fibre damage and repair may be key to the assessment of efficacy in clinical trials of disease modifying therapies for diabetic neuropathy.
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Affiliation(s)
- Rayaz A Malik
- Department of Medicine, Weill-Cornell Medicine-Qatar, Doha, Qatar
- Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester, Manchester, UK
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Jonas R, Prato V, Lechner SG, Groen G, Obreja O, Werland F, Rukwied R, Klusch A, Petersen M, Carr RW, Schmelz M. TTX-Resistant Sodium Channels Functionally Separate Silent From Polymodal C-nociceptors. Front Cell Neurosci 2020; 14:13. [PMID: 32116559 PMCID: PMC7018684 DOI: 10.3389/fncel.2020.00013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 01/17/2020] [Indexed: 01/09/2023] Open
Abstract
Pronounced activity-dependent slowing of conduction has been used to characterize mechano-insensitive, “silent” nociceptors and might be due to high expression of NaV1.8 and could, therefore, be characterized by their tetrodotoxin-resistance (TTX-r). Nociceptor-class specific differences in action potential characteristics were studied by: (i) in vitro calcium imaging in single porcine nerve growth factor (NGF)-responsive neurites; (ii) in vivo extracellular recordings in functionally identified porcine silent nociceptors; and (iii) in vitro patch-clamp recordings from murine silent nociceptors, genetically defined by nicotinic acetylcholine receptor subunit alpha-3 (CHRNA3) expression. Porcine TTX-r neurites (n = 26) in vitro had more than twice as high calcium transients per action potential as compared to TTX-s neurites (n = 18). In pig skin, silent nociceptors (n = 14) characterized by pronounced activity-dependent slowing of conduction were found to be TTX-r, whereas polymodal nociceptors were TTX-s (n = 12) and had only moderate slowing. Mechano-insensitive cold nociceptors were also TTX-r but showed less activity-dependent slowing than polymodal nociceptors. Action potentials in murine silent nociceptors differed from putative polymodal nociceptors by longer duration and higher peak amplitudes. Longer duration AP in silent murine nociceptors linked to increased sodium load would be compatible with a pronounced activity-dependent slowing in pig silent nociceptors and longer AP durations could be in line with increased calcium transients per action potential observed in vitro in TTX-resistant NGF responsive porcine neurites. Even though there is no direct link between slowing and TTX-resistant channels, the results indicate that axons of silent nociceptors not only differ in their receptive but also in their axonal properties.
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Affiliation(s)
- Robin Jonas
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Vincenzo Prato
- Institute of Pharmacology, University of Heidelberg, Heidelberg, Germany
| | - Stefan G Lechner
- Institute of Pharmacology, University of Heidelberg, Heidelberg, Germany
| | - Gerbrand Groen
- Department of Anesthesiology, Groningen University, Groningen, Netherlands
| | - Otilia Obreja
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Fiona Werland
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Roman Rukwied
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Andreas Klusch
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Marlen Petersen
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Richard W Carr
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Martin Schmelz
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
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Nguyen HD, Okada T, Sekiguchi F, Tsubota M, Nishikawa H, Kawabata A, Toyooka N. Prenylflavanones as Novel T-Type Calcium Channel Blockers Useful for Pain Therapy. Nat Prod Commun 2019. [DOI: 10.1177/1934578x19873441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Prenylated flavonoids have attracted much attention due to their promising and diverse bioactivities on multitarget tissues. To the best of our knowledge, our recent studies demonstrated first that (2 S)-6-prenylnaringenin (6-PNG), a hop component, blocks Cav3.2 T-type calcium channels (T-channels) and alleviates neuropathic and visceral pain with little side effects; it also indicated first that other natural prenylflavanones (PFVNs), such as sophoraflavanone G and (2 S)-8-PNG, or synthetic 6-PFVNs including (2 R/S)-6-PNG and its derivatives are capable of blocking T-channels and useful for pain therapy. Through the structure-activity relationship studies on the synthetic 6-PFVNs, we identified 6-(3-ethylpent-2-enyl)-5,7-dihydroxy-2-(2-hydroxyphenyl)chroman-4-one (8j or KTt-45) as the most potent blocker of Cav3.2 T-channels. It is interesting to recognize a prenylated flavonoid, belonging to other sub-classes, as a novel T-channel blocker. Therefore, this article will review some of our recent studies to introduce a new branch to researchers studying on prenylated flavonoids.
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Affiliation(s)
- Huy Du Nguyen
- Graduate School of Innovative Life Science, University of Toyama, Japan
| | - Takuya Okada
- Graduate School of Innovative Life Science, University of Toyama, Japan
| | - Fumiko Sekiguchi
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, Japan
| | - Maho Tsubota
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, Japan
| | - Hiroyuki Nishikawa
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, Japan
| | - Atsufumi Kawabata
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, Japan
| | - Naoki Toyooka
- Graduate School of Innovative Life Science, University of Toyama, Japan
- Graduate School of Science and Engineering, University of Toyama, Japan
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T-type calcium channels: From molecule to therapeutic opportunities. Int J Biochem Cell Biol 2019; 108:34-39. [DOI: 10.1016/j.biocel.2019.01.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/08/2019] [Accepted: 01/11/2019] [Indexed: 12/27/2022]
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Designing and conducting proof-of-concept chronic pain analgesic clinical trials. Pain Rep 2019; 4:e697. [PMID: 31583338 PMCID: PMC6749910 DOI: 10.1097/pr9.0000000000000697] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 09/24/2018] [Accepted: 09/26/2018] [Indexed: 02/07/2023] Open
Abstract
Introduction: The evolution of pain treatment is dependent on successful development and testing of interventions. Proof-of-concept (POC) studies bridge the gap between identification of a novel target and evaluation of the candidate intervention's efficacy within a pain model or the intended clinical pain population. Methods: This narrative review describes and evaluates clinical trial phases, specific POC pain trials, and approaches to patient profiling. Results: We describe common POC trial designs and their value and challenges, a mechanism-based approach, and statistical issues for consideration. Conclusion: Proof-of-concept trials provide initial evidence for target use in a specific population, the most appropriate dosing strategy, and duration of treatment. A significant goal in designing an informative and efficient POC study is to ensure that the study is safe and sufficiently sensitive to detect a preliminary efficacy signal (ie, a potentially valuable therapy). Proof-of-concept studies help avoid resources wasted on targets/molecules that are not likely to succeed. As such, the design of a successful POC trial requires careful consideration of the research objective, patient population, the particular intervention, and outcome(s) of interest. These trials provide the basis for future, larger-scale studies confirming efficacy, tolerability, side effects, and other associated risks.
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Devor M. Rethinking the causes of pain in herpes zoster and postherpetic neuralgia: the ectopic pacemaker hypothesis. Pain Rep 2018; 3:e702. [PMID: 30706041 PMCID: PMC6344138 DOI: 10.1097/pr9.0000000000000702] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/10/2018] [Indexed: 01/29/2023] Open
Abstract
INTRODUCTION Pain in herpes zoster (HZ) and postherpetic neuralgia (PHN) is traditionally explained in terms of 2 processes: irritable nociceptors in the rash-inflamed skin and, later, deafferentation due to destruction of sensory neurons in one virally infected dorsal root ganglion. OBJECTIVES AND METHODS Consideration of the evidence supporting this explanation in light of contemporary understanding of the pain system finds it wanting. An alternative hypothesis is proposed as a replacement. RESULTS This model, the ectopic pacemaker hypothesis of HZ and PHN, proposes that pain in both conditions is driven by hyperexcitable ectopic pacemaker sites at various locations in primary sensory neurons affected by the causative varicella zoster virus infection. This peripheral input is exacerbated by central sensitization induced and maintained by the ectopic activity. CONCLUSIONS The shift in perspective regarding the pain mechanism in HZ/PHN has specific implications for clinical management.
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Affiliation(s)
- Marshall Devor
- Department of Cell and Developmental Biology, Institute of Life Sciences, and Center for Research on Pain, The Hebrew University of Jerusalem, Jerusalem, Israel
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Wang D, Ragnarsson L, Lewis RJ. T-type Calcium Channels in Health and Disease. Curr Med Chem 2018; 27:3098-3122. [PMID: 30277145 DOI: 10.2174/0929867325666181001112821] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/28/2018] [Accepted: 08/30/2018] [Indexed: 12/12/2022]
Abstract
Low Voltage-Activated (LVA) T-type calcium channels are characterized by transient current and Low Threshold Spikes (LTS) that trigger neuronal firing and oscillatory behavior. Combined with their preferential localization in dendrites and their specific "window current", T-type calcium channels are considered to be key players in signal amplification and synaptic integration. Assisted by the emerging pharmacological tools, the structural determinants of channel gating and kinetics, as well as novel physiological and pathological functions of T-type calcium channels, are being uncovered. In this review, we provide an overview of structural determinants in T-type calcium channels, their involvement in disorders and diseases, the development of novel channel modulators, as well as Structure-Activity Relationship (SAR) studies that lead to rational drug design.
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Affiliation(s)
- Dan Wang
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, the University of Queensland, Brisbane Qld 4072, Australia
| | - Lotten Ragnarsson
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, the University of Queensland, Brisbane Qld 4072, Australia
| | - Richard J Lewis
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, the University of Queensland, Brisbane Qld 4072, Australia
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McGaraughty S, Chu KL, Xu J. Characterization and pharmacological modulation of noci-responsive deep dorsal horn neurons across diverse rat models of pathological pain. J Neurophysiol 2018; 120:1893-1905. [DOI: 10.1152/jn.00325.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This overview compares the activity of wide dynamic range (WDR) and nociceptive specific (NS) neurons located in the deep dorsal horn across different rat models of pathological pain and following modulation by diverse pharmacology. The data were collected by our group under the same experimental conditions over numerous studies to facilitate comparison. Spontaneous firing of WDR neurons was significantly elevated (>3.7 Hz) in models of neuropathic, inflammation, and osteoarthritic pain compared with naive animals (1.9 Hz) but was very low (<0.5 Hz) and remained unchanged in NS neurons. WDR responses to low-intensity mechanical stimulation were elevated in neuropathic and inflammation models. WDR responses to high-intensity stimuli were enhanced in inflammatory (heat) and osteoarthritis (mechanical) models. NS responses to high-intensity stimulation did not change relative to control in any model examined. Several therapeutic agents reduced both evoked and spontaneous firing of WDR neurons (e.g., TRPV1, TRPV3, Nav1.7, Nav1.8, P2X7, P2X3, H3), other targets affected neither evoked nor spontaneous firing of WDR neurons (e.g., H4, TRPM8, KCNQ2/3), and some only modulated evoked (e.g, ASIC1a, Cav3.2) whereas others decreased evoked but affected spontaneous activity only in specific models (e.g., TRPA1, CB2). Spontaneous firing of WDR neurons was not altered by any peripherally restricted compound or by direct administration of compounds to peripheral sites, although the same compounds decreased evoked activity. Compounds acting centrally were effective against this endpoint. The diversity of incoming/modulating inputs to the deep dorsal horn positions this group of neurons as an important intersection within the pain system to validate novel therapeutics. NEW & NOTEWORTHY Data from multiple individual experiments were combined to show firing properties of wide dynamic range and nociceptive specific spinal dorsal horn neurons across varied pathological pain models. This high-powered analysis describes the sensitization following different forms of injury. Effects of diverse pharmacology on these neurons is also summarized from published and unpublished data all recorded under the same conditions to facilitate comparison. This comprehensive overview describes the function and utility of these neurons.
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Affiliation(s)
| | | | - Jun Xu
- AbbVie Discovery, North Chicago, Illinois
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Ackerley R, Watkins RH. Microneurography as a tool to study the function of individual C-fiber afferents in humans: responses from nociceptors, thermoreceptors, and mechanoreceptors. J Neurophysiol 2018; 120:2834-2846. [PMID: 30256737 DOI: 10.1152/jn.00109.2018] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The technique of microneurography-recording neural traffic from nerves in awake humans-has provided us with unrivaled insights into afferent and efferent processes in the peripheral nervous system for over 50 years. We review the use of microneurography to study single C-fiber afferents and provide an overview of the knowledge gained, with views to future investigations. C-fibers have slowly conducting, thin-diameter, unmyelinated axons and make up the majority of the fibers in peripheral nerves (~80%). With the use of microneurography in humans, C-fiber afferents have been differentiated into discrete subclasses that encode specific qualities of stimuli on the skin, and their functional roles have been investigated. Afferent somatosensory information provided by C-fibers underpins various positive and negative affective sensations from the periphery, including mechanical, thermal, and chemical pain (C-nociceptors), temperature (C-thermoreceptors), and positive affective aspects of touch (C-tactile afferents). Insights from microneurographic investigations have revealed the complexity of the C-fiber system, methods for delineating fundamental C-fiber populations in a translational manner, how C-fiber firing can be used to identify nerve deficits in pathological states, and how the responses from C-fibers may be modified to change sensory percepts, including decreasing pain. Understanding these processes may lead to future medical interventions to diagnose and treat C-fiber dysfunction. NEW & NOTEWORTHY The technique of microneurography allows us to directly investigate the functional roles of single C-fiber afferents in awake human beings. Here we outline and discuss the current field of C-fiber research on this heterogeneous population of afferents in healthy subjects, in pathological states, and from a translational perspective. We cover C-fibers encoding touch, temperature, and pain and provide perspectives on the future of C-fiber microneurography investigations in humans.
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Affiliation(s)
- Rochelle Ackerley
- Aix Marseille University, CNRS, LNSC (Laboratoire de Neurosciences Sensorielles et Cognitives - UMR 7260), Marseille, France.,Department of Physiology, University of Gothenburg , Gothenburg , Sweden
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Sekiguchi F, Fujita T, Deguchi T, Yamaoka S, Tomochika K, Tsubota M, Ono S, Horaguchi Y, Ichii M, Ichikawa M, Ueno Y, Koike N, Tanino T, Nguyen HD, Okada T, Nishikawa H, Yoshida S, Ohkubo T, Toyooka N, Murata K, Matsuda H, Kawabata A. Blockade of T-type calcium channels by 6-prenylnaringenin, a hop component, alleviates neuropathic and visceral pain in mice. Neuropharmacology 2018; 138:232-244. [PMID: 29913186 DOI: 10.1016/j.neuropharm.2018.06.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 05/30/2018] [Accepted: 06/14/2018] [Indexed: 10/14/2022]
Abstract
Since Cav3.2 T-type Ca2+ channels (T-channels) expressed in the primary afferents and CNS contribute to intractable pain, we explored T-channel-blocking components in distinct herbal extracts using a whole-cell patch-clamp technique in HEK293 cells stably expressing Cav3.2 or Cav3.1, and purified and identified sophoraflavanone G (SG) as an active compound from SOPHORAE RADIX (SR). Interestingly, hop-derived SG analogues, (2S)-6-prenylnaringenin (6-PNG) and (2S)-8-PNG, but not naringenin, also blocked T-channels; IC50 (μM) of SG, (2S)-6-PNG and (2S)-8-PNG was 0.68-0.75 for Cav3.2 and 0.99-1.41 for Cav3.1. (2S)-6-PNG and (2S)-8-PNG, but not SG, exhibited reversible inhibition. The racemic (2R/S)-6-PNG as well as (2S)-6-PNG potently blocked Cav3.2, but exhibited minor effect on high-voltage-activated Ca2+ channels and voltage-gated Na+ channels in differentiated NG108-15 cells. In mice, the mechanical allodynia following intraplantar (i.pl.) administration of an H2S donor was abolished by oral or i.p. SR extract and by i.pl. SG, (2S)-6-PNG or (2S)-8-PNG, but not naringenin. Intraperitoneal (2R/S)-6-PNG strongly suppressed visceral pain and spinal ERK phosphorylation following intracolonic administration of an H2S donor in mice. (2R/S)-6-PNG, administered i.pl. or i.p., suppressed the neuropathic allodynia induced by partial sciatic nerve ligation or oxaliplatin, an anti-cancer agent, in mice. (2R/S)-6-PNG had little or no effect on open-field behavior, motor performance or cardiovascular function in mice, and on the contractility of isolated rat aorta. (2R/S)-6-PNG, but not SG, was detectable in the brain after their i.p. administration in mice. Our data suggest that 6-PNG, a hop component, blocks T-channels, and alleviates neuropathic and visceral pain with little side effects.
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Affiliation(s)
- Fumiko Sekiguchi
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Tomoyo Fujita
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Takahiro Deguchi
- Division of Natural Drug Resources, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Sakura Yamaoka
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Ken Tomochika
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Maho Tsubota
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Sumire Ono
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Yamato Horaguchi
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Maki Ichii
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Mio Ichikawa
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Yumiko Ueno
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Nene Koike
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Tadatoshi Tanino
- Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, 770-8514, Japan
| | - Huy Du Nguyen
- Graduate School of Innovative Life Science, University of Toyama, Toyama, 930-8555, Japan
| | - Takuya Okada
- Graduate School of Innovative Life Science, University of Toyama, Toyama, 930-8555, Japan
| | - Hiroyuki Nishikawa
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Shigeru Yoshida
- Department of Life Science, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Tsuyako Ohkubo
- Division of Basic Medical Sciences and Fundamental Nursing, Faculty of Nursing, Fukuoka Nursing College, Fukuoka, 814-0193, Japan
| | - Naoki Toyooka
- Graduate School of Innovative Life Science, University of Toyama, Toyama, 930-8555, Japan; Graduate School of Science and Engineering, University of Toyama, Toyama, 930-8555, Japan
| | - Kazuya Murata
- Division of Natural Drug Resources, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Hideaki Matsuda
- Division of Natural Drug Resources, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan
| | - Atsufumi Kawabata
- Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Higashi-Osaka, 577-8502, Japan.
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Snutch TP, Zamponi GW. Recent advances in the development of T-type calcium channel blockers for pain intervention. Br J Pharmacol 2018; 175:2375-2383. [PMID: 28608534 PMCID: PMC5980537 DOI: 10.1111/bph.13906] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 05/19/2017] [Accepted: 06/05/2017] [Indexed: 01/15/2023] Open
Abstract
Cav 3.2 T-type calcium channels are important regulators of pain signals in the afferent pain pathway, and their activities are dysregulated during various chronic pain states. Therefore, it is reasonable to predict that inhibiting T-type calcium channels in dorsal root ganglion neurons and in the spinal dorsal horn can be targeted for pain relief. This is supported by early pharmacological studies with T-type channel blockers, such as ethosuximide, and by analgesic effects of siRNA depletion of Cav 3.2 channels. In the past 5 years, considerable effort has been applied towards identifying novel classes of T-type calcium channel blockers. Here, we review recent developments in the discovery of novel classes of T-type calcium channel blockers, and their analgesic effects in animal models of pain and in clinical trials. LINKED ARTICLES This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.
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Affiliation(s)
- Terrance P Snutch
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of MedicineUniversity of CalgaryCalgaryABCanada
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Kikkert S, Johansen-Berg H, Tracey I, Makin TR. Reaffirming the link between chronic phantom limb pain and maintained missing hand representation. Cortex 2018; 106:174-184. [PMID: 30005369 PMCID: PMC6143485 DOI: 10.1016/j.cortex.2018.05.013] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 04/16/2018] [Accepted: 05/23/2018] [Indexed: 12/20/2022]
Abstract
Phantom limb pain (PLP) is commonly considered to be a result of maladaptive brain plasticity. This model proposes that PLP is mainly caused by reorganisation in the primary somatosensory cortex, presumably characterised by functional degradation of the missing hand representation and remapping of other body part representations. In the current study, we replicate our previous results by showing that chronic PLP correlates with maintained representation of the missing hand in the primary sensorimotor missing hand cortex. We asked unilateral upper-limb amputees to move their phantom hand, lips or other body parts and measured the associated neural responses using functional magnetic resonance imaging (fMRI). We confirm that amputees suffering from worse chronic PLP have stronger activity in the primary sensorimotor missing hand cortex while performing phantom hand movements. We find no evidence of lip representation remapping into the missing hand territory, as assessed by measuring activity in the primary sensorimotor missing hand cortex during lip movements. We further show that the correlation between chronic PLP and maintained representation of the missing hand cannot be explained by the experience of chronic non-painful phantom sensations or compensatory usage of the residual arm or an artificial arm (prosthesis). Together, our results reaffirm a likely relationship between persistent peripheral inputs pertaining to the missing hand representation and chronic PLP. Our findings emphasise a need to further study the role of peripheral inputs from the residual nerves to better understand the mechanisms underlying chronic PLP.
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Affiliation(s)
- Sanne Kikkert
- Wellcome Centre for Integrative Neuroimaging, MRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Heidi Johansen-Berg
- Wellcome Centre for Integrative Neuroimaging, MRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Irene Tracey
- Wellcome Centre for Integrative Neuroimaging, MRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom
| | - Tamar R Makin
- Wellcome Centre for Integrative Neuroimaging, MRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Institute of Cognitive Neuroscience, University College London, London, United Kingdom.
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Tsantoulas C, Laínez S, Wong S, Mehta I, Vilar B, McNaughton PA. Hyperpolarization-activated cyclic nucleotide-gated 2 (HCN2) ion channels drive pain in mouse models of diabetic neuropathy. Sci Transl Med 2018; 9:eaam6072. [PMID: 28954930 DOI: 10.1126/scitranslmed.aam6072] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/22/2017] [Accepted: 09/06/2017] [Indexed: 01/12/2023]
Abstract
Diabetic patients frequently suffer from continuous pain that is poorly treated by currently available analgesics. We used mouse models of type 1 and type 2 diabetes to investigate a possible role for the hyperpolarization-activated cyclic nucleotide-gated 2 (HCN2) ion channels as drivers of diabetic pain. Blocking or genetically deleting HCN2 channels in small nociceptive neurons suppressed diabetes-associated mechanical allodynia and prevented neuronal activation of second-order neurons in the spinal cord in mice. In addition, we found that intracellular cyclic adenosine monophosphate (cAMP), a positive HCN2 modulator, is increased in somatosensory neurons in an animal model of painful diabetes. We propose that the increased intracellular cAMP drives diabetes-associated pain by facilitating HCN2 activation and consequently promoting repetitive firing in primary nociceptive nerve fibers. Our results suggest that HCN2 may be an analgesic target in the treatment of painful diabetic neuropathy.
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Affiliation(s)
- Christoforos Tsantoulas
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK
| | - Sergio Laínez
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK
| | - Sara Wong
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK
| | - Ishita Mehta
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK
| | - Bruno Vilar
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK
| | - Peter A McNaughton
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK.
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50
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Jayaraj ND, Bhattacharyya BJ, Belmadani AA, Ren D, Rathwell CA, Hackelberg S, Hopkins BE, Gupta HR, Miller RJ, Menichella DM. Reducing CXCR4-mediated nociceptor hyperexcitability reverses painful diabetic neuropathy. J Clin Invest 2018. [PMID: 29533926 DOI: 10.1172/jci92117] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Painful diabetic neuropathy (PDN) is an intractable complication of diabetes that affects 25% of patients. PDN is characterized by neuropathic pain and small-fiber degeneration, accompanied by dorsal root ganglion (DRG) nociceptor hyperexcitability and loss of their axons within the skin. The molecular mechanisms underlying DRG nociceptor hyperexcitability and small-fiber degeneration in PDN are unknown. We hypothesize that chemokine CXCL12/CXCR4 signaling is central to this mechanism, as we have shown that CXCL12/CXCR4 signaling is necessary for the development of mechanical allodynia, a pain hypersensitivity behavior common in PDN. Focusing on DRG neurons expressing the sodium channel Nav1.8, we applied transgenic, electrophysiological, imaging, and chemogenetic techniques to test this hypothesis. In the high-fat diet mouse model of PDN, we were able to prevent and reverse mechanical allodynia and small-fiber degeneration by limiting CXCR4 signaling or neuronal excitability. This study reveals that excitatory CXCR4/CXCL12 signaling in Nav1.8-positive DRG neurons plays a critical role in the pathogenesis of mechanical allodynia and small-fiber degeneration in a mouse model of PDN. Hence, we propose that targeting CXCR4-mediated DRG nociceptor hyperexcitability is a promising therapeutic approach for disease-modifying treatments for this currently intractable and widespread affliction.
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Affiliation(s)
| | | | - Abdelhak A Belmadani
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Dongjun Ren
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Craig A Rathwell
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | | | - Brittany E Hopkins
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Herschel R Gupta
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Richard J Miller
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Daniela M Menichella
- Department of Neurology and.,Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
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