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Gupta A, Vejapi M, Knezevic NN. The role of nitric oxide and neuroendocrine system in pain generation. Mol Cell Endocrinol 2024; 591:112270. [PMID: 38750811 DOI: 10.1016/j.mce.2024.112270] [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] [Revised: 03/13/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024]
Abstract
Previous studies have indicated a complex interplay between the nitric oxide (NO) pain signaling pathways and hormonal signaling pathways in the body. This article delineates the role of nitric oxide signaling in neuropathic and inflammatory pain generation and subsequently discusses how the neuroendocrine system is involved in pain generation. Hormonal systems including the hypothalamic-pituitary axis (HPA) generation of cortisol, the renin-angiotensin-aldosterone system, calcitonin, melatonin, and sex hormones could potentially contribute to the generation of nitric oxide involved in the sensation of pain. Further research is necessary to clarify this relationship and may reveal therapeutic targets involving NO signaling that alleviate neuropathic and inflammatory pain.
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Affiliation(s)
- Aayush Gupta
- Department of Anesthesiology, Advocate Illinois Masonic Medical Center, Chicago, IL, USA; Rosalind Franklin University of Medicine and Science, USA
| | - Maja Vejapi
- Department of Anesthesiology, Advocate Illinois Masonic Medical Center, Chicago, IL, USA
| | - Nebojsa Nick Knezevic
- Department of Anesthesiology, Advocate Illinois Masonic Medical Center, Chicago, IL, USA; Department of Anesthesiology, University of Illinois, Chicago, IL, USA; Department of Surgery, University of Illinois, Chicago, IL, USA.
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2
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Mustafa S, Bajic JE, Barry B, Evans S, Siemens KR, Hutchinson MR, Grace PM. One immune system plays many parts: The dynamic role of the immune system in chronic pain and opioid pharmacology. Neuropharmacology 2023; 228:109459. [PMID: 36775098 PMCID: PMC10015343 DOI: 10.1016/j.neuropharm.2023.109459] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/06/2023] [Accepted: 02/08/2023] [Indexed: 02/12/2023]
Abstract
The transition from acute to chronic pain is an ongoing major problem for individuals, society and healthcare systems around the world. It is clear chronic pain is a complex multidimensional biological challenge plagued with difficulties in pain management, specifically opioid use. In recent years the role of the immune system in chronic pain and opioid pharmacology has come to the forefront. As a highly dynamic and versatile network of cells, tissues and organs, the immune system is perfectly positioned at the microscale level to alter nociception and drive structural adaptations that underpin chronic pain and opioid use. In this review, we highlight the need to understand the dynamic and adaptable characteristics of the immune system and their role in the transition, maintenance and resolution of chronic pain. The complex multidimensional interplay of the immune system with multiple physiological systems may provide new transformative insight for novel targets for clinical management and treatment of chronic pain. This article is part of the Special Issue on "Opioid-induced changes in addiction and pain circuits".
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Affiliation(s)
- Sanam Mustafa
- School of Biomedicine, The University of Adelaide, Adelaide, SA, Australia; Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, The University of Adelaide, Adelaide, SA, Australia; Davies Livestock Research Centre, The University of Adelaide, Roseworthy, SA, Australia.
| | - Juliana E Bajic
- School of Biomedicine, The University of Adelaide, Adelaide, SA, Australia; Davies Livestock Research Centre, The University of Adelaide, Roseworthy, SA, Australia
| | - Benjamin Barry
- School of Biomedicine, The University of Adelaide, Adelaide, SA, Australia
| | - Samuel Evans
- School of Biomedicine, The University of Adelaide, Adelaide, SA, Australia; Davies Livestock Research Centre, The University of Adelaide, Roseworthy, SA, Australia
| | - Kariel R Siemens
- School of Biomedicine, The University of Adelaide, Adelaide, SA, Australia
| | - Mark R Hutchinson
- School of Biomedicine, The University of Adelaide, Adelaide, SA, Australia; Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, The University of Adelaide, Adelaide, SA, Australia; Davies Livestock Research Centre, The University of Adelaide, Roseworthy, SA, Australia
| | - Peter M Grace
- Laboratories of Neuroimmunology, Department of Symptom Research, University of Texas MD Anderson Cancer Center, Houston, TX, USA; MD Anderson Pain Research Consortium, Houston, TX, USA
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Pike CK, Kim M, Schnitzer K, Mercaldo N, Edwards R, Napadow V, Zhang Y, Morrissey EJ, Alshelh Z, Evins AE, Loggia ML, Gilman JM. Study protocol for a phase II, double-blind, randomised controlled trial of cannabidiol (CBD) compared with placebo for reduction of brain neuroinflammation in adults with chronic low back pain. BMJ Open 2022; 12:e063613. [PMID: 36123113 PMCID: PMC9486315 DOI: 10.1136/bmjopen-2022-063613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
INTRODUCTION Chronic pain is a debilitating medical problem that is difficult to treat. Neuroinflammatory pathways have emerged as a potential therapeutic target, as preclinical studies have demonstrated that glial cells and neuroglial interactions play a role in the establishment and maintenance of pain. Recently, we used positron emission tomography (PET) to demonstrate increased levels of 18 kDa translocator protein (TSPO) binding, a marker of glial activation, in patients with chronic low back pain (cLBP). Cannabidiol (CBD) is a glial inhibitor in animal models, but studies have not assessed whether CBD reduces neuroinflammation in humans. The principal aim of this trial is to evaluate whether CBD, compared with placebo, affects neuroinflammation, as measured by TSPO levels. METHODS AND ANALYSIS This is a double-blind, randomised, placebo-controlled, phase II clinical trial. Eighty adults (aged 18-75) with cLBP for >6 months will be randomised to either an FDA-approved CBD medication (Epidiolex) or matching placebo for 4 weeks using a dose-escalation design. All participants will undergo integrated PET/MRI at baseline and after 4 weeks of treatment to evaluate neuroinflammation using [11C]PBR28, a second-generation radioligand for TSPO. Our primary hypothesis is that participants randomised to CBD will demonstrate larger reductions in thalamic [11C]PBR28 signal compared with those receiving placebo. We will also assess the effect of CBD on (1) [11C]PBR28 signal from limbic regions, which our prior work has linked to depressive symptoms and (2) striatal activation in response to a reward task. Additionally, we will evaluate self-report measures of cLBP intensity and bothersomeness, depression and quality of life at baseline and 4 weeks. ETHICS AND DISSEMINATION This protocol is approved by the Massachusetts General Brigham Human Research Committee (protocol number: 2021P002617) and FDA (IND number: 143861) and registered with ClinicalTrials.gov. Results will be published in peer-reviewed journals and presented at conferences. TRIAL REGISTRATION NUMBER NCT05066308; ClinicalTrials.gov.
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Affiliation(s)
- Chelsea K Pike
- Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA
- Massachusetts General Hospital Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, USA
| | - Minhae Kim
- Massachusetts General Hospital Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, USA
| | - Kristina Schnitzer
- Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, USA
| | - Nathaniel Mercaldo
- Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Robert Edwards
- Department of Anesthesiology, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Vitaly Napadow
- Massachusetts General Hospital Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, USA
- Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Charlestown, Massachusetts, USA
| | - Yi Zhang
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Erin Janas Morrissey
- Massachusetts General Hospital Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, USA
| | - Zeynab Alshelh
- Massachusetts General Hospital Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, USA
- Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - A Eden Evins
- Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, USA
| | - Marco L Loggia
- Massachusetts General Hospital Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, USA
- Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Jodi M Gilman
- Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA
- Massachusetts General Hospital Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, USA
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, USA
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Jergova S, Hernandez M, Sagen J. Analgesic effect of recombinant GABAergic precursors releasing MVIIA in a model of peripheral nerve injury in rats. Mol Pain 2022; 18:17448069221129829. [PMID: 36113096 PMCID: PMC9513588 DOI: 10.1177/17448069221129829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Development of chronic pain has been attributed to dysfunctional GABA signaling in the
spinal cord. Direct pharmacological interventions on GABA signaling are usually not very
efficient and often accompanied by side effects due to the widespread distribution of GABA
receptors in CNS. Transplantation of GABAergic neuronal cells may restore the inhibitory
potential in the spinal cord. Grafted cells may also release additional analgesic peptides
by means of genetic engineering to further enhance the benefits of this approach.
Conopeptides are ideal candidates for recombinant expression using cell-based strategies.
The omega-conopeptide MVIIA is in clinical use for severe pain marketed as FDA approved
Prialt in the form of intrathecal injections. The goal of this study was to develop
transplantable recombinant GABAergic cells releasing conopeptide MVIIA and to evaluate the
analgesic effect of the grafts in a model of peripheral nerve injury-induced pain. We have
engineered and characterized the GABAergic progenitors expressing MVIIA. Recombinant and
nonrecombinant cells were intraspinally injected into animals after the nerve injury.
Animals were tested weekly up to 12 weeks for the presence of hypersensitivity, followed
by histochemical and biochemical analysis of the tissue. We observed beneficial effects of
the grafted cells in reducing hypersensitivity in all grafted animals, especially potent
in the recombinant group. The level of pain-related cytokines was reduced in the grafted
animals and correlation between these pain markers and actual behavior was indicated. This
study demonstrated the feasibility of recombinant cell transplantation in the management
of chronic pain.
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Pottorf TS, Rotterman TM, McCallum WM, Haley-Johnson ZA, Alvarez FJ. The Role of Microglia in Neuroinflammation of the Spinal Cord after Peripheral Nerve Injury. Cells 2022; 11:cells11132083. [PMID: 35805167 PMCID: PMC9265514 DOI: 10.3390/cells11132083] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 06/26/2022] [Accepted: 06/27/2022] [Indexed: 12/12/2022] Open
Abstract
Peripheral nerve injuries induce a pronounced immune reaction within the spinal cord, largely governed by microglia activation in both the dorsal and ventral horns. The mechanisms of activation and response of microglia are diverse depending on the location within the spinal cord, type, severity, and proximity of injury, as well as the age and species of the organism. Thanks to recent advancements in neuro-immune research techniques, such as single-cell transcriptomics, novel genetic mouse models, and live imaging, a vast amount of literature has come to light regarding the mechanisms of microglial activation and alluding to the function of microgliosis around injured motoneurons and sensory afferents. Herein, we provide a comparative analysis of the dorsal and ventral horns in relation to mechanisms of microglia activation (CSF1, DAP12, CCR2, Fractalkine signaling, Toll-like receptors, and purinergic signaling), and functionality in neuroprotection, degeneration, regeneration, synaptic plasticity, and spinal circuit reorganization following peripheral nerve injury. This review aims to shed new light on unsettled controversies regarding the diversity of spinal microglial-neuronal interactions following injury.
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Affiliation(s)
- Tana S. Pottorf
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
| | - Travis M. Rotterman
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30318, USA;
| | - William M. McCallum
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
| | - Zoë A. Haley-Johnson
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
| | - Francisco J. Alvarez
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
- Correspondence:
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Miranpuri GS, Bali P, Nguyen J, Kim JJ, Modgil S, Mehra P, Buttar S, Brown G, Yutuc N, Singh H, Wood A, Singh J, Anand A. Role of Microglia and Astrocytes in Spinal Cord Injury Induced Neuropathic Pain. Ann Neurosci 2022; 28:219-228. [PMID: 35341227 PMCID: PMC8948321 DOI: 10.1177/09727531211046367] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 08/03/2021] [Indexed: 12/30/2022] Open
Abstract
Background: Spinal cord injuries incite varying degrees of symptoms in patients, ranging
from weakness and incoordination to paralysis. Common amongst spinal cord
injury (SCI) patients, neuropathic pain (NP) is a debilitating medical
condition. Unfortunately, there remain many clinical impediments in treating
NP because there is a lack of understanding regarding the mechanisms behind
SCI-induced NP (SCINP). Given that more than 450,000 people in the United
States alone suffer from SCI, it is unsatisfactory that current treatments
yield poor results in alleviating and treating NP. Summary: In this review, we briefly discussed the models of SCINP along with the
mechanisms of NP progression. Further, current treatment modalities are
herein explored for SCINP involving pharmacological interventions targeting
glia cells and astrocytes. Key message: The studies presented in this review provide insight for new directions
regarding SCINP alleviation. Given the severity and incapacitating effects
of SCINP, it is imperative to study the pathways involved and find new
therapeutic targets in coordination with stem cell research, and to develop
a new gold-standard in SCINP treatment.
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Affiliation(s)
- Gurwattan S Miranpuri
- Department of Neurological Surgery, University of Wisconsin, School of Medicine and Public Health, Madison, Wisconsin, United States
| | - Parul Bali
- Department of Biological Sciences, Indian Institute of Science Education & Research Mohali, India
| | - Justyn Nguyen
- Department of Neurological Surgery, University of Wisconsin, School of Medicine and Public Health, Madison, Wisconsin, United States
| | - Jason J Kim
- Department of Neurological Surgery, University of Wisconsin, School of Medicine and Public Health, Madison, Wisconsin, United States
| | - Shweta Modgil
- Neuroscience research lab, Department of Neurology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Priya Mehra
- Neuroscience research lab, Department of Neurology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India.,Department of Biotechnology, Panjab University, Chandigarh, India
| | - Seah Buttar
- Department of Neurological Surgery, University of Wisconsin, School of Medicine and Public Health, Madison, Wisconsin, United States
| | - Greta Brown
- Department of Neurological Surgery, University of Wisconsin, School of Medicine and Public Health, Madison, Wisconsin, United States
| | - Noemi Yutuc
- Department of Neurological Surgery, University of Wisconsin, School of Medicine and Public Health, Madison, Wisconsin, United States
| | - Harpreet Singh
- Department of Neurological Surgery, University of Wisconsin, School of Medicine and Public Health, Madison, Wisconsin, United States
| | - Aleksandar Wood
- Department of Neurological Surgery, University of Wisconsin, School of Medicine and Public Health, Madison, Wisconsin, United States
| | - Jagtar Singh
- Department of Biotechnology, Panjab University, Chandigarh, India
| | - Akshay Anand
- Neuroscience research lab, Department of Neurology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India.,CCRYN- Collaborative Centre for Mind Body Intervention through Yoga.,Centre of Phenomenology and Cognitive Sciences, Panjab University, Chandigarh, India
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Xie AX, Taves S, McCarthy K. Nuclear Factor κB-COX2 Pathway Activation in Non-myelinating Schwann Cells Is Necessary for the Maintenance of Neuropathic Pain in vivo. Front Cell Neurosci 2022; 15:782275. [PMID: 35095422 PMCID: PMC8795077 DOI: 10.3389/fncel.2021.782275] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/23/2021] [Indexed: 11/17/2022] Open
Abstract
Chronic neuropathic pain leads to long-term changes in the sensitivity of both peripheral and central nociceptive neurons. Glial fibrillary acidic protein (GFAP)-positive glial cells are closely associated with the nociceptive neurons including astrocytes in the central nervous system (CNS), satellite glial cells (SGCs) in the sensory ganglia, and non-myelinating Schwann cells (NMSCs) in the peripheral nerves. Central and peripheral GFAP-positive cells are involved in the maintenance of chronic pain through a host of inflammatory cytokines, many of which are under control of the transcription factor nuclear factor κB (NFκB) and the enzyme cyclooxygenase 2 (COX2). To test the hypothesis that inhibiting GFAP-positive glial signaling alleviates chronic pain, we used (1) a conditional knockout (cKO) mouse expressing Cre recombinase under the hGFAP promoter and a floxed COX2 gene to inactivate the COX2 gene specifically in GFAP-positive cells; and (2) a tet-Off tetracycline transactivator system to suppress NFκB activation in GFAP-positive cells. We found that neuropathic pain behavior following spared nerve injury (SNI) significantly decreased in COX2 cKO mice as well as in mice with decreased glial NFκB signaling. Additionally, experiments were performed to determine whether central or peripheral glial NFκB signaling contributes to the maintenance of chronic pain behavior following nerve injury. Oxytetracycline (Oxy), a blood-brain barrier impermeable analog of doxycycline was employed to restrict transgene expression to CNS glia only, leaving peripheral glial signaling intact. Signaling inactivation in central GFAP-positive glia alone failed to exhibit the same analgesic effects as previously observed in animals with both central and peripheral glial signaling inhibition. These data suggest that the NFκB-COX2 signaling pathway in NMSCs is necessary for the maintenance of neuropathic pain in vivo.
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Affiliation(s)
- Alison Xiaoqiao Xie
- Department of Surgery, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- *Correspondence: Alison Xiaoqiao Xie,
| | - Sarah Taves
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Ken McCarthy
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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Interaction of Opioids with TLR4-Mechanisms and Ramifications. Cancers (Basel) 2021; 13:cancers13215274. [PMID: 34771442 PMCID: PMC8582379 DOI: 10.3390/cancers13215274] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/09/2021] [Accepted: 10/17/2021] [Indexed: 12/14/2022] Open
Abstract
Simple Summary Recent evidence indicates that opioids can be active at a receptor that is abundantly expressed on innate immune cells as well as cancer cells: the receptor is termed toll-like receptor 4 (TLR4). TLR4 is increasingly recognised as playing key roles in tumour biology and anticancer defences. However, the issue of whether TLR4 mediates some of the effects of opioids on tumour growth and metastasis is entirely unknown. We review existing evidence, mechanisms, and functional consequences of the action of opioids at TLR4. This opens new avenues of research on the role of opioids in cancer. Abstract The innate immune receptor toll-like receptor 4 (TLR4) is known as a sensor for the gram-negative bacterial cell wall component lipopolysaccharide (LPS). TLR4 activation leads to a strong pro-inflammatory response in macrophages; however, it is also recognised to play a key role in cancer. Recent studies of the opioid receptor (OR)-independent actions of opioids have identified that TLR4 can respond to opioids. Opioids are reported to weakly activate TLR4, but to significantly inhibit LPS-induced TLR4 activation. The action of opioids at TLR4 is suggested to be non-stereoselective, this is because OR-inactive (+)-isomers of opioids have been shown to activate or to inhibit TLR4 signalling, although there is some controversy in the literature. While some opioids can bind to the lipopolysaccharide (LPS)-binding cleft of the Myeloid Differentiation factor 2 (MD-2) co-receptor, pharmacological characterisation of the inhibition of opioids on LPS activation of TLR4 indicates a noncompetitive mechanism. In addition to a direct interaction at the receptor, opioids affect NF-κB activation downstream of both TLR4 and opioid receptors and modulate TLR4 expression, leading to a range of in vivo outcomes. Here, we review the literature reporting the activity of opioids at TLR4, its proposed mechanism(s), and the complex functional consequences of this interaction.
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Rezaei M, Karimian L, Shafaghi B, Noubarani M, Salecheh M, Shafi Dehghani M, Eskandari MR, Pourahmad J. Evaluation of Molecular and Cellular Alterations Induced by Neuropathic Pain in Rat Brain Glial cells. IRANIAN JOURNAL OF PHARMACEUTICAL RESEARCH : IJPR 2021; 20:359-370. [PMID: 34400965 PMCID: PMC8170759 DOI: 10.22037/ijpr.2020.113052.14089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Neuropathic pain originates from illness or damage of the nervous system and affects the somatosensory system. Recently, many efforts have been made to illuminate the influences of neuropathic pain in different parts of central nervous system (CNS). However, the toxic consequences of neuropathic pain in glial cells, which involve in the control of pain is poorly understood. Therefore, the present study aimed to assess the molecular and cellular effects of neuropathic pain in the glial cells of rat brain. Induction of neuropathic pain in rats was associated with oxidative stress as evident by elevated reactive oxygen species (ROS) formation as well as reversible glutathione (GSH) depletion in the glial cells. Moreover, neuropathic pain caused mitochondrial membrane potential collapse (∆Ψm%), lysosomal membrane rapture, and proteolysis, probably due to ROS-induced MPT pore opening. These toxic events could cause cytochrome c release from intermembrane space into the cytosole and trigger caspase activation pathway. Our finding confirmed that the activity of caspase-3 was significantly increased in the glial cells as a core component of the apoptotic machinery. In conclusion, the neuropathic pain induces ROS generation as the major cause of GSH depletion along with mutual mitochondrial/lysosomal potentiation (cross-talk) of oxidative stress in the glial cells. Subsequently, this toxic cross-talk can induce proteolysis and trigger apoptosis by caspase-3 activation in the glial cells of rat brain.
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Affiliation(s)
- Mohsen Rezaei
- Department of Toxicology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Lida Karimian
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Bizhan Shafaghi
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Maryam Noubarani
- Department of Pharmacology and Toxicology, School of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Maryam Salecheh
- Department of Pharmacology and Toxicology, School of Pharmacy, Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mohammad Shafi Dehghani
- Department of Pharmacology and Toxicology, School of Pharmacy, Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mohammad Reza Eskandari
- Zanjan Pharmaceutical Nanotechnology Research Center (ZPNRC), Zanjan University of Medical Sciences, Zanjan, Iran.,Department of Pharmacology and Toxicology, School of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Jalal Pourahmad
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Prospects for the Personalized Multimodal Therapy Approach to Pain Management via Action on NO and NOS. Molecules 2021; 26:molecules26092431. [PMID: 33921984 PMCID: PMC8122598 DOI: 10.3390/molecules26092431] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/17/2021] [Accepted: 04/19/2021] [Indexed: 12/15/2022] Open
Abstract
Chronic pain syndromes are an important medical problem generated by various molecular, genetic, and pathophysiologic mechanisms. Back pain, neuropathic pain, and posttraumatic pain are the most important pathological processes associated with chronic pain in adults. Standard approaches to the treatment of them do not solve the problem of pain chronicity. This is the reason for the search for new personalized strategies for the prevention and treatment of chronic pain. The nitric oxide (NO) system can play one of the key roles in the development of peripheral pain and its chronicity. The purpose of the study is to review publications devoted to changes in the NO system in patients with peripheral chronical pain syndromes. We have carried out a search for the articles published in e-Library, PubMed, Oxford Press, Clinical Case, Springer, Elsevier, and Google Scholar databases. The search was carried out using keywords and their combinations. The role of NO and NO synthases (NOS) isoforms in peripheral pain development and chronicity was demonstrated primarily from animal models to humans. The most studied is the neuronal NOS (nNOS). The role of inducible NOS (iNOS) and endothelial NOS (eNOS) is still under investigation. Associative genetic studies have shown that single nucleotide variants (SNVs) of NOS1, NOS2, and NOS3 genes encoding nNOS, iNOS, and eNOS may be associated with acute and chronic peripheral pain. Prospects for the use of NOS inhibitors to modulate the effect of drugs used to treat peripheral pain syndrome are discussed. Associative genetic studies of SNVs NOS1, NOS2, and NOS3 genes are important for understanding genetic predictors of peripheral pain chronicity and development of new personalized pharmacotherapy strategies.
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Use of low-dose naltrexone in the management of chronic pain conditions: A systematic review. J Am Dent Assoc 2021; 151:891-902.e1. [PMID: 33228882 DOI: 10.1016/j.adaj.2020.08.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 08/19/2020] [Indexed: 12/23/2022]
Abstract
BACKGROUND The authors aimed to evaluate the efficacy of low-dose naltrexone in the management of chronic pain conditions and determine its potential use in orofacial pain management. METHODS A comprehensive literature review was completed in the PubMed/MEDLINE, Embase, Cumulated Index to Nursing and Allied Health Literature, Dentistry and Oral Sciences Source Library databases up through June 17, 2019, using terms such as neurogenic, inflammation, naltrexone, temporomandibular, and chronic pain. The primary outcome was reduction in pain intensity and, secondarily, improvement in quality of life. RESULTS A total of 793 studies were obtained with the initial search and 8 articles were selected for evaluation. Of these 8 articles, 4 were case reports, 3 were clinical studies, and 1 was a randomized controlled trial. Six studies included data on fibromyalgia, 2 studies included data on chronic regional pain syndrome, and 1 examined multiple diagnoses, including fibromyalgia, interstitial cystitis, and chronic pelvic pain. The primary outcome of all of the studies was pain intensity reduction. CONCLUSIONS AND PRACTICAL IMPLICATIONS Low-dose naltrexone provides an alternative in medical management of chronic pain disorders as a novel anti-inflammatory and immunomodulator. It can offer additional management options, as orofacial pain conditions share characteristics with other chronic pain disorders. Owing to the size and heterogeneity of the studies, more large-scale studies are needed, along with additional studies assessing orofacial pain response to low-dose naltrexone.
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The Neuroimmunology of Chronic Pain: From Rodents to Humans. J Neurosci 2020; 41:855-865. [PMID: 33239404 DOI: 10.1523/jneurosci.1650-20.2020] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/29/2020] [Accepted: 10/04/2020] [Indexed: 12/11/2022] Open
Abstract
Chronic pain, encompassing conditions, such as low back pain, arthritis, persistent post-surgical pain, fibromyalgia, and neuropathic pain disorders, is highly prevalent but remains poorly treated. The vast majority of therapeutics are directed solely at neurons, despite the fact that signaling between immune cells, glia, and neurons is now recognized as indispensable for the initiation and maintenance of chronic pain. This review highlights recent advances in understanding fundamental neuroimmune signaling mechanisms and novel therapeutic targets in rodent models of chronic pain. We further discuss new technological developments to study, diagnose, and quantify neuroimmune contributions to chronic pain in patient populations.
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13
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Rinne M, Mätlik K, Ahonen T, Vedovi F, Zappia G, Moreira VM, Yli-Kauhaluoma J, Leino S, Salminen O, Kalso E, Airavaara M, Xhaard H. Mitoxantrone, pixantrone and mitoxantrone (2-hydroxyethyl)piperazine are toll-like receptor 4 antagonists, inhibit NF-κB activation, and decrease TNF-alpha secretion in primary microglia. Eur J Pharm Sci 2020; 154:105493. [PMID: 32730846 DOI: 10.1016/j.ejps.2020.105493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 07/22/2020] [Accepted: 07/27/2020] [Indexed: 10/23/2022]
Abstract
Toll-like receptor 4 (TLR4) recognizes various endogenous and microbial ligands and is an essential part in the innate immune system. TLR4 signaling initiates transcription factor NF-κB and production of proinflammatory cytokines. TLR4 contributes to the development or progression of various diseases including stroke, neuropathic pain, multiple sclerosis, rheumatoid arthritis and cancer, and better therapeutics are currently sought for these conditions. In this study, a library of 140 000 compounds was virtually screened and a resulting hit-list of 1000 compounds was tested using a cellular reporter system. The topoisomerase II inhibitor mitoxantrone and its analogues pixantrone and mitoxantrone (2-hydroxyethyl)piperazine were identified as inhibitors of TLR4 and NF-κB activation. Mitoxantrone was shown to bind directly to the TLR4, and pixantrone and mitoxantrone (2-hydroxyethyl)piperazine were shown to inhibit the production of proinflammatory cytokines such as tumor necrosis factor alpha (TNFα) in primary microglia. The inhibitory effect on NF-κB activation or on TNFα production was not mediated through cytotoxity at ≤ 1 µM concentration for pixantrone and mitoxantrone (2-hydroxyethyl)piperazine treated cells, as assessed by ATP counts. This study thus identifies a new mechanism of action for mitoxantrone, pixantrone, and mitoxantrone (2-hydroxyethyl)piperazine through the TLR4.
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Affiliation(s)
- Maiju Rinne
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland
| | - Kert Mätlik
- Institute of Biotechnology, HiLIFE, University of Helsinki, FI-00014 Helsinki, Finland; Department of Pharmacology, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Tiina Ahonen
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland
| | - Fabio Vedovi
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland; Department of Biomolecular Sciences, University Urbino Carlo Bo, P.zza Rinascimento, 6 61029 Urbino (PU), Italy
| | - Giovanni Zappia
- Department of Biomolecular Sciences, University Urbino Carlo Bo, P.zza Rinascimento, 6 61029 Urbino (PU), Italy
| | - Vânia M Moreira
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland; Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, G4 0RE Glasgow, U.K; Laboratory of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Coimbra, 3004-548 Coimbra, Portugal; Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Jari Yli-Kauhaluoma
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland
| | - Sakari Leino
- Drug Research Program, Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland
| | - Outi Salminen
- Drug Research Program, Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland
| | - Eija Kalso
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland; Department of Anaesthesiology, Intensive Care and Pain Medicine, University of Helsinki and Helsinki University Hospital. FI-00029 HUS, Finland
| | - Mikko Airavaara
- Institute of Biotechnology, HiLIFE, University of Helsinki, FI-00014 Helsinki, Finland
| | - Henri Xhaard
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland.
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The ambiguity of opioids revealed by immunology is changing the knowledge and the therapeutic approach in cancer and non-cancer pain: A narrative review. Immunol Lett 2020; 226:12-21. [DOI: 10.1016/j.imlet.2020.06.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 06/17/2020] [Indexed: 12/18/2022]
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15
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Lu G, Pang C, Chen Y, Wu N, Li J. Aquaporin 4 is involved in chronic pain but not acute pain. Behav Brain Res 2020; 393:112810. [PMID: 32681852 DOI: 10.1016/j.bbr.2020.112810] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 05/23/2020] [Accepted: 07/14/2020] [Indexed: 12/27/2022]
Abstract
Accumulating evidence has revealed that spinal glia plays an important role in the processing of pain, particularly chronic pain. Aquaporin 4 (AQP4), the predominant water channel exists in astrocytes, has been proved to modulate astrocytic function and thus participate in many diseases of the central nervous system. However, there is still controversy over whether AQP4 is involved in pain modulation. In the present study, we investigated the effects of AQP4 on pain by examining chronic inflammatory pain, neuropathic pain, and thermal, chemical, and mechanical stimuli-induced acute pain in AQP4 knockout mice. In Complete Freund's adjuvant-induced chronic inflammatory pain and spared nerve injury-induced neuropathic pain models, AQP4-/- mice attenuated pain-related behavioral responses compared with AQP4+/+ mice, demonstrating that AQP4 deficiency relieved chronic inflammatory pain and neuropathic pain. In the tail-flick and hot-plate tests, two acute pain models of thermal stimuli, no differences in pain-related behaviors were detected between AQP4+/+ and AQP4-/- mice. In the formalin and capsaicin tests, two models of chemical stimuli-induced acute pain, no differences in the durations of licking the injected hindpaw were found between AQP4+/+ and AQP4-/- mice. In the von Frey hair test, a model of mechanical stimuli-induced acute pain, no significant differences in withdrawal thresholds were found between these two genotypes mice as well. These results indicated that AQP4 deficiency did not affect acute pain induced by thermal, chemical, and mechanical stimuli. Taken together, our findings suggested that AQP4 contributes to chronic pain, but not acute pain.
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Affiliation(s)
- Guanyi Lu
- Beijing Key Laboratory of Neuropsychopharmacology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Chong Pang
- Beijing Key Laboratory of Neuropsychopharmacology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Ying Chen
- Beijing Key Laboratory of Neuropsychopharmacology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Ning Wu
- Beijing Key Laboratory of Neuropsychopharmacology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
| | - Jin Li
- Beijing Key Laboratory of Neuropsychopharmacology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
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16
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Donnelly CR, Andriessen AS, Chen G, Wang K, Jiang C, Maixner W, Ji RR. Central Nervous System Targets: Glial Cell Mechanisms in Chronic Pain. Neurotherapeutics 2020; 17:846-860. [PMID: 32820378 PMCID: PMC7609632 DOI: 10.1007/s13311-020-00905-7] [Citation(s) in RCA: 133] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Interactions between central glial cells and neurons in the pain circuitry are critical contributors to the pathogenesis of chronic pain. In the central nervous system (CNS), two major glial cell types predominate: astrocytes and microglia. Injuries or pathological conditions which evoke pain are concurrently associated with the presence of a reactive microglia or astrocyte state, which is characterized by a variety of changes in the morphological, molecular, and functional properties of these cells. In this review, we highlight the changes that reactive microglia and astrocytes undergo following painful injuries and insults and discuss the critical and interactive role these two cell types play in the initiation and maintenance of chronic pain. Additionally, we focus on several crucial mechanisms by which microglia and astrocytes contribute to chronic pain and provide commentary on the therapeutic promise of targeting these pathways. In particular, we discuss how the inflammasome in activated microglia drives maturation and release of key pro-inflammatory cytokines, which drive pain through neuronal- and glial regulations. Moreover, we highlight several potentially-druggable hemichannels and proteases produced by reactive microglia and astrocytes in pain states and discuss how these pathways regulate distinct phases during pain pathogenesis. We also review two emerging areas in chronic pain research: 1) sexually dimorphic glial cell signaling and 2) the role of oligodendrocytes. Finally, we highlight important considerations for potential pain therapeutics targeting glial cell mediators as well as questions that remain in our conceptual understanding of glial cell activation in pain states.
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Affiliation(s)
- Christopher R Donnelly
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA.
| | - Amanda S Andriessen
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Gang Chen
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Kaiyuan Wang
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Changyu Jiang
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - William Maixner
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Ru-Rong Ji
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA.
- Department of Neurobiology, Duke University Medical Center, Durham, NC, 27710, USA.
- Department of Cell Biology, Duke University Medical Center, Durham, NC, 27710, USA.
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17
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Analgesic Mechanism of Sinomenine against Chronic Pain. Pain Res Manag 2020; 2020:1876862. [PMID: 32454918 PMCID: PMC7225909 DOI: 10.1155/2020/1876862] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 04/17/2020] [Accepted: 04/22/2020] [Indexed: 02/06/2023]
Abstract
Purified from the roots of the plant Sinomenium acutum, sinomenine is traditionally used in China and Japan for treating rheumatism and arthritis. Previously, we have demonstrated that sinomenine possessed a broad analgesic spectrum in various chronic pain animal models and repeated administration of sinomenine did not generate tolerance. In this review article, we discussed sinomenine's analgesic mechanism with focus on its role on immune regulation and neuroimmune interaction. Sinomenine has distinct immunoregulative properties, in which glutamate, adenosine triphosphate, nitric oxide, and proinflammatory cytokines are thought to be involved. Sinomenine may alter the unbalanced neuroimmune interaction and inhibit neuroinflammation, oxidative stress, and central sensitization in chronic pain states. In conclusion, sinomenine has promising potential for chronic pain management in different clinical settings.
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18
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MEL endomorphins act as potent inflammatory analgesics with the inhibition of activated non-neuronal cells and modulation of pro-inflammatory cytokines. Neuropharmacology 2020; 168:107992. [DOI: 10.1016/j.neuropharm.2020.107992] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 01/24/2020] [Accepted: 02/05/2020] [Indexed: 12/23/2022]
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19
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Dworsky-Fried Z, Kerr BJ, Taylor AMW. Microbes, microglia, and pain. NEUROBIOLOGY OF PAIN 2020; 7:100045. [PMID: 32072077 PMCID: PMC7016021 DOI: 10.1016/j.ynpai.2020.100045] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 01/23/2020] [Accepted: 01/24/2020] [Indexed: 02/08/2023]
Abstract
Explore the connection between the gut microbiome and microglia in chronic pain. Discuss mechanisms by which gut bacteria might influence microglia to contribute to chronic pain. Highlight gaps in knowledge and discuss future directions for the field.
Globally, it is estimated that one in five people suffer from chronic pain, with prevalence increasing with age. The pathophysiology of chronic pain encompasses complex sensory, immune, and inflammatory interactions within both the central and peripheral nervous systems. Microglia, the resident macrophages of the central nervous system (CNS), are critically involved in the initiation and persistence of chronic pain. Microglia respond to local signals from the CNS but are also modulated by signals from the gastrointestinal tract. Emerging data from preclinical and clinical studies suggest that communication between the gut microbiome, the community of bacteria residing within the gut, and microglia is involved in producing chronic pain. Targeted strategies that manipulate or restore the gut microbiome have been shown to reduce microglial activation and alleviate symptoms associated with inflammation. These data indicate that manipulations of the gut microbiome in chronic pain patients might be a viable strategy in improving pain outcomes. Herein, we discuss the evidence for a connection between microglia and the gut microbiome and explore the mechanisms by which commensal bacteria might influence microglial reactivity to drive chronic pain.
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Affiliation(s)
- Zoë Dworsky-Fried
- Department of Pharmacology, University of Alberta, Edmonton T6G2H7, Canada
| | - Bradley J Kerr
- Department of Pharmacology, University of Alberta, Edmonton T6G2H7, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton T6G2H7, Canada.,Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton T6G2H7, Canada
| | - Anna M W Taylor
- Department of Pharmacology, University of Alberta, Edmonton T6G2H7, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton T6G2H7, Canada.,Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton T6G2H7, Canada
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20
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Cinelli MA, Do HT, Miley GP, Silverman RB. Inducible nitric oxide synthase: Regulation, structure, and inhibition. Med Res Rev 2020; 40:158-189. [PMID: 31192483 PMCID: PMC6908786 DOI: 10.1002/med.21599] [Citation(s) in RCA: 364] [Impact Index Per Article: 91.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 04/14/2019] [Accepted: 05/13/2019] [Indexed: 12/11/2022]
Abstract
A considerable number of human diseases have an inflammatory component, and a key mediator of immune activation and inflammation is inducible nitric oxide synthase (iNOS), which produces nitric oxide (NO) from l-arginine. Overexpressed or dysregulated iNOS has been implicated in numerous pathologies including sepsis, cancer, neurodegeneration, and various types of pain. Extensive knowledge has been accumulated about the roles iNOS plays in different tissues and organs. Additionally, X-ray crystal and cryogenic electron microscopy structures have shed new insights on the structure and regulation of this enzyme. Many potent iNOS inhibitors with high selectivity over related NOS isoforms, neuronal NOS, and endothelial NOS, have been discovered, and these drugs have shown promise in animal models of endotoxemia, inflammatory and neuropathic pain, arthritis, and other disorders. A major issue in iNOS inhibitor development is that promising results in animal studies have not translated to humans; there are no iNOS inhibitors approved for human use. In addition to assay limitations, both the dual modalities of iNOS and NO in disease states (ie, protective vs harmful effects) and the different roles and localizations of NOS isoforms create challenges for therapeutic intervention. This review summarizes the structure, function, and regulation of iNOS, with focus on the development of iNOS inhibitors (historical and recent). A better understanding of iNOS' complex functions is necessary before specific drug candidates can be identified for classical indications such as sepsis, heart failure, and pain; however, newer promising indications for iNOS inhibition, such as depression, neurodegenerative disorders, and epilepsy, have been discovered.
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Affiliation(s)
- Maris A. Cinelli
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Center for Developmental Therapeutics, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
- Current address: Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824
| | - Ha T. Do
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Center for Developmental Therapeutics, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
- Current address: Mersana Therapeutics, Inc., Cambridge, MA 02139
| | - Galen P. Miley
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Center for Developmental Therapeutics, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Richard B. Silverman
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Center for Developmental Therapeutics, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
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21
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Larson CM, Wilcox GL, Fairbanks CA. The Study of Pain in Rats and Mice. Comp Med 2019; 69:555-570. [PMID: 31822322 PMCID: PMC6935695 DOI: 10.30802/aalas-cm-19-000062] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/17/2019] [Accepted: 09/30/2019] [Indexed: 01/07/2023]
Abstract
Pain is a clinical syndrome arising from a variety of etiologies in a heterogeneous population, which makes successfully treating the individual patient difficult. Organizations and governments recognize the need for tailored and specific therapies, which drives pain research. This review summarizes the different types of pain assessments currently being used and the various rodent models that have been developed to recapitulate the human pain condition.
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Affiliation(s)
- Christina M Larson
- Comparative and Molecular Biosciences, University of Minnesota College of Veterinary Medicine, St Paul, Minnesota
| | - George L Wilcox
- Departments of Neuroscience, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Carolyn A Fairbanks
- Departments of Neuroscience, University of Minnesota Medical School, Minneapolis, Minnesota;,
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22
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Abstract
Astrocytes are critical for maintaining the homeostasis of the CNS. Increasing evidence suggests that a number of neurological and neuropsychiatric disorders, including chronic pain, may result from astrocyte 'gliopathy'. Indeed, in recent years there has been substantial progress in our understanding of how astrocytes can regulate nociceptive synaptic transmission via neuronal-glial and glial-glial cell interactions, as well as the involvement of spinal and supraspinal astrocytes in the modulation of pain signalling and the maintenance of neuropathic pain. A role of astrocytes in the pathogenesis of chronic itch is also emerging. These developments suggest that targeting the specific pathways that are responsible for astrogliopathy may represent a novel approach to develop therapies for chronic pain and chronic itch.
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23
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Chung KF. IFN-γ: A Driver of Cough Hypersensitivity Pathways in Chronic Cough? Am J Respir Crit Care Med 2019; 198:827-828. [PMID: 29758165 DOI: 10.1164/rccm.201804-0740ed] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Kian Fan Chung
- 1 National Heart and Lung Institute Imperial College London London, United Kingdom and.,2 Royal Brompton and Harefield NHS Trust London, United Kingdom
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24
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Diverse Role of Biological Plasticity in Low Back Pain and Its Impact on Sensorimotor Control of the Spine. J Orthop Sports Phys Ther 2019; 49:389-401. [PMID: 31151376 DOI: 10.2519/jospt.2019.8716] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Pain is complex. It is no longer acceptable to consider pain solely as a peripheral phenomenon involving activation of nociceptive neurons. The contemporary understanding of pain involves consideration of different underlying pain mechanisms and an increasing awareness of plasticity in all of the biological systems. Of note, recent advances in technology and understanding have highlighted the critical importance of neuroimmune interactions, both in the peripheral and central nervous systems, and the interaction between the nervous system and body tissues in the development and maintenance of pain, including low back pain (LBP). Further, the biology of many tissues changes when challenged by pain and injury, as reported in a growing body of literature on the biology of muscle, fat, and connective tissue. These advances in understanding of the complexity of LBP have implications for our understanding of pain and its interaction with the motor system, and may change how we consider motor control in the rehabilitation of LBP. This commentary provides a state-of-the-art overview of plasticity of biology in LBP. The paper is divided into 4 parts that address (1) biology of pain mechanisms, (2) neuroimmune interaction in the central nervous system, (3) neuroimmune interaction in the periphery, and (4) brain and peripheral tissue interaction. Each section considers the implications for clinical management of LBP. J Orthop Sports Phys Ther 2019;49(6):389-401. doi:10.2519/jospt.2019.8716.
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Inhibition of spinal 15-LOX-1 attenuates TLR4-dependent, nonsteroidal anti-inflammatory drug-unresponsive hyperalgesia in male rats. Pain 2019; 159:2620-2629. [PMID: 30130298 DOI: 10.1097/j.pain.0000000000001373] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Although nonsteroidal anti-inflammatory drugs are the first line of therapeutics for the treatment of mild to moderate somatic pain, they are not generally considered to be effective for neuropathic pain. In the current study, direct activation of spinal Toll-like 4 receptors (TLR4) by the intrathecal (IT) administration of KDO2 lipid A (KLA), the active component of lipopolysaccharide, elicits a robust tactile allodynia that is unresponsive to cyclooxygenase inhibition, despite elevated expression of cyclooxygenase metabolites in the spinal cord. Intrathecal KLA increases 12-lipoxygenase-mediated hepoxilin production in the lumbar spinal cord, concurrent with expression of the tactile allodynia. The TLR4-induced hepoxilin production was also observed in primary spinal microglia, but not in astrocytes, and was accompanied by increased microglial expression of the 12/15-lipoxygenase enzyme 15-LOX-1. Intrathecal KLA-induced tactile allodynia was completely prevented by spinal pretreatment with the 12/15-lipoxygenase inhibitor CDC or a selective antibody targeting rat 15-LOX-1. Similarly, pretreatment with the selective inhibitors ML127 or ML351 both reduced activity of the rat homolog of 15-LOX-1 heterologously expressed in HEK-293T cells and completely abrogated nonsteroidal anti-inflammatory drug-unresponsive allodynia in vivo after IT KLA. Finally, spinal 12/15-lipoxygenase inhibition by nordihydroguaiaretic acid (NDGA) both prevents phase II formalin flinching and reverses formalin-induced persistent tactile allodynia. Taken together, these findings suggest that spinal TLR4-mediated hyperpathic states are mediated at least in part through activation of microglial 15-LOX-1.
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Nanocarrier-mediated Delivery of CORM-2 Enhances Anti-allodynic and Anti-hyperalgesic Effects of CORM-2. Mol Neurobiol 2019; 56:5539-5554. [PMID: 30637664 DOI: 10.1007/s12035-019-1468-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 01/04/2019] [Indexed: 12/16/2022]
Abstract
Neuropathic pain is a devastating chronic condition and effective treatments are still lacking. Carbon monoxide-releasing molecule-2 (CORM-2) as a carbon monoxide (CO) carrier, exerts potent anti-neuropathic pain effects; however, its poor water solubility and short half-life hinder its clinical utility. Therefore, the aim of this study was to investigate whether CORM-2-loaded solid lipid nanoparticles (CORM-2-SLNs) enhance the anti-allodynic and anti-hyperalgesic effects of CORM-2 in a rat chronic constriction injury (CCI) model. CORM-2-SLNs were prepared using a nanotemplate engineering technique with slight modifications. The physiochemical properties of CORM-2-SLNs were characterized and CO release from CORM-2-SLNs was assessed using a myoglobin assay. CO was slowly released from CORM-2-SLNs, was observed, and the half-life of CO release was 50 times longer than that of CORM-2. In vivo results demonstrate that intraperitoneal administration of CORM-2-SLNs (5 and 10 mg/kg/day, ip) once daily for seven consecutive days significantly reduced the mechanical allodynia and mechanical hyperalgesia compared with CORM-2 (10 mg/kg/day, ip). RT-PCR and Western blot analyses on days 7 and 14, revealed that treatment with CORM-2-SLNs resulted in greater reductions in the CCI-elevated levels of heme-oxygenase-2 (HO-2); inducible nitric oxide synthase (iNOS); neuronal NOS (nNOS); and inflammatory mediators (TNF-α, IBA-1, and GFAP) in the spinal cord and dorsal root ganglions compared with treatment with CORM-2. In contrast, HO-1 and IL-10 were significantly increased in the CORM-2-SLN-treated group compared with the group treated with CORM-2. These data indicate that CORM-2-SLNs are superior to CORM-2-S in alleviating mechanical allodynia and mechanical hyperalgesia.
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27
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Albrecht D, Ahmed S, Kettner N, Borra R, Cohen-Adad J, Deng H, Houle T, Opalacz A, Roth S, Melo MV, Chen L, Mao J, Hooker J, Loggia ML, Zhang Y. Neuroinflammation of the spinal cord and nerve roots in chronic radicular pain patients. Pain 2018; 159:968-977. [PMID: 29419657 PMCID: PMC5908728 DOI: 10.1097/j.pain.0000000000001171] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Numerous preclinical studies support the role of spinal neuroimmune activation in the pathogenesis of chronic pain, and targeting glia (eg, microglia/astrocyte)- or macrophage-mediated neuroinflammatory responses effectively prevents or reverses the establishment of persistent nocifensive behaviors in laboratory animals. However, thus far, the translation of those findings into novel treatments for clinical use has been hindered by the scarcity of data supporting the role of neuroinflammation in human pain. Here, we show that patients suffering from a common chronic pain disorder (lumbar radiculopathy), compared with healthy volunteers, exhibit elevated levels of the neuroinflammation marker 18 kDa translocator protein, in both the neuroforamina (containing dorsal root ganglion and nerve roots) and spinal cord. These elevations demonstrated a pattern of spatial specificity correlating with the patients' clinical presentation, as they were observed in the neuroforamen ipsilateral to the symptomatic leg (compared with both contralateral neuroforamen in the same patients as well as to healthy controls) and in the most caudal spinal cord segments, which are known to process sensory information from the lumbosacral nerve roots affected in these patients (compared with more superior segments). Furthermore, the neuroforaminal translocator protein signal was associated with responses to fluoroscopy-guided epidural steroid injections, supporting its role as an imaging marker of neuroinflammation, and highlighting the clinical significance of these observations. These results implicate immunoactivation at multiple levels of the nervous system as a potentially important and clinically relevant mechanism in human radicular pain, and suggest that therapies targeting immune cell activation may be beneficial for chronic pain patients.
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Affiliation(s)
- Daniel Albrecht
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02129
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114
| | - Shihab Ahmed
- MGH Translational Pain Research Center, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston MA 02114
| | - Norman Kettner
- Department of Radiology, Logan University, Chesterfield, MO, 63017
| | - Ronald Borra
- Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku, Finland; Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Julien Cohen-Adad
- Department of Electrical Engineering, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, Quebec, Canada; Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montreal, Quebec, Canada
| | - Hao Deng
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston MA 02114
| | - Timothy Houle
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston MA 02114
| | - Arissa Opalacz
- MGH Translational Pain Research Center, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston MA 02114
| | - Sarah Roth
- MGH Translational Pain Research Center, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston MA 02114
| | - Marcos Vidal Melo
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston MA 02114
| | - Lucy Chen
- MGH Translational Pain Research Center, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston MA 02114
| | - Jianren Mao
- MGH Translational Pain Research Center, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston MA 02114
| | - Jacob Hooker
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02129
| | - Marco L Loggia
- A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02129
| | - Yi Zhang
- MGH Translational Pain Research Center, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston MA 02114
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Vanderwall AG, Noor S, Sun MS, Sanchez JE, Yang XO, Jantzie LL, Mellios N, Milligan ED. Effects of spinal non-viral interleukin-10 gene therapy formulated with d-mannose in neuropathic interleukin-10 deficient mice: Behavioral characterization, mRNA and protein analysis in pain relevant tissues. Brain Behav Immun 2018; 69:91-112. [PMID: 29113923 PMCID: PMC5857419 DOI: 10.1016/j.bbi.2017.11.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/20/2017] [Accepted: 11/03/2017] [Indexed: 12/17/2022] Open
Abstract
Studies show that spinal (intrathecal; i.t.) interleukin-10 (IL-10) gene therapy reverses neuropathic pain in animal models, and co-administration with the mannose receptor (MR; CD206) ligand d-mannose (DM) greatly improves therapeutic efficacy. However, the actions of endogenous IL-10 may be required for enduring pain control observed following i.t. IL-10 gene therapy, potentially narrowing the application of this non-viral transgene delivery approach. Here, we show that i.t. application of naked plasmid DNA expressing the IL-10 transgene co-injected with DM (DM/pDNA-IL-10) for the treatment of peripheral neuropathic pain in IL-10 deficient (IL-10 KO) mice results in a profound and prolonged bilateral pain suppression. Neuropathic pain is induced by unilateral sciatic chronic constriction injury (CCI), and while enduring relief of light touch sensitivity (mechanical allodynia) in both wild type (WT) and IL-10 KO mice was observed following DM/pDNA-IL-10 co-therapy, transient reversal from allodynia was observed following i.t. DM alone. In stably pain-relieved IL-10 KO mice given DM/pDNA-IL-10, mRNA for the IL-10 transgene is detected in the cauda equina and ipsilateral dorsal root ganglia (DRG), but not the lumbar spinal cord. Further, DM/pDNA-IL-10 application increases anti-inflammatory TGF-β1 and decreases pro-inflammatory TNF mRNA in the ipsilateral DRG compared to allodynic controls. Additionally, DM/pDNA-IL-10 treated mice exhibit decreased spinal pro-inflammatory mRNA expression for TNF, CCL2 (MCP-1), and for the microglial-specific marker TMEM119. Similarly, DM/pDNA-IL-10 treatment decreases immunoreactivity for the astrocyte activation marker GFAP in lumbar spinal cord dorsal horn. Despite transient reversal and early return to allodynia in DM-treated mice, lumbar spinal cord revealed elevated TNF, CCL2 and TMEM119 mRNA levels. Both MR (CD206) and IL-10 receptor mRNAs are increased in the DRG following CCI manipulation independent of injection treatment, suggesting that pathological conditions stimulate upregulation and availability of relevant receptors in critical anatomical regions required for the therapeutic actions of the DM/pDNA-IL-10 co-therapy. Taken together, the current report demonstrates that non-viral DM/pDNA-IL-10 gene therapy does not require endogenous IL-10 for enduring relief of peripheral neuropathic pain and does not require direct contact with the spinal cord dorsal horn for robust and enduring relief of neuropathic pain. Spinal non-viral DM/pDNA-IL-10 co-therapy may offer a framework for the development of non-viral gene therapeutic approaches for other diseases of the central nervous system.
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Affiliation(s)
- Arden G Vanderwall
- Department of Neurosciences, University of New Mexico School of Medicine, UNM Health Sciences Center, Albuquerque, NM 87131-0001, USA; Department of Anesthesiology & Critical Care Medicine, University of New Mexico School of Medicine, UNM Health Sciences Center, Albuquerque, NM 87131-0001, USA
| | - Shahani Noor
- Department of Neurosciences, University of New Mexico School of Medicine, UNM Health Sciences Center, Albuquerque, NM 87131-0001, USA
| | - Melody S Sun
- Department of Neurosciences, University of New Mexico School of Medicine, UNM Health Sciences Center, Albuquerque, NM 87131-0001, USA
| | - Jacob E Sanchez
- Department of Neurosciences, University of New Mexico School of Medicine, UNM Health Sciences Center, Albuquerque, NM 87131-0001, USA
| | - Xuexian O Yang
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, UNM Health Sciences Center, Albuquerque, NM 87131-0001, USA
| | - Lauren L Jantzie
- Department of Neurosciences, University of New Mexico School of Medicine, UNM Health Sciences Center, Albuquerque, NM 87131-0001, USA; Department of Pediatrics, University of New Mexico School of Medicine, UNM Health Sciences Center, Albuquerque, NM 87131-0001, USA
| | - Nikolaos Mellios
- Department of Neurosciences, University of New Mexico School of Medicine, UNM Health Sciences Center, Albuquerque, NM 87131-0001, USA
| | - Erin D Milligan
- Department of Neurosciences, University of New Mexico School of Medicine, UNM Health Sciences Center, Albuquerque, NM 87131-0001, USA; Department of Anesthesiology & Critical Care Medicine, University of New Mexico School of Medicine, UNM Health Sciences Center, Albuquerque, NM 87131-0001, USA.
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29
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Wen J, Jones M, Tanaka M, Selvaraj P, Symes AJ, Cox B, Zhang Y. WWL70 protects against chronic constriction injury-induced neuropathic pain in mice by cannabinoid receptor-independent mechanisms. J Neuroinflammation 2018; 15:9. [PMID: 29310667 PMCID: PMC5759843 DOI: 10.1186/s12974-017-1045-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/19/2017] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Targeting the endocannabinoid system has emerged as an effective strategy for the treatment of inflammatory and neurological diseases. Unlike the inhibition of the principal 2-arachidonyl glycerol (2-AG) hydrolytic enzyme monoacylglycerol lipase (MAGL), which leads to 2-AG overload and cannabinoid receptor desensitization, selective inhibition of the minor 2-AG hydrolytic enzyme alpha, beta-hydrolase domain 6 (ABHD6) can provide therapeutic benefits without producing cannabimimetic side effects. We have shown that inhibition of ABHD6 significantly reduces neuroinflammation and exerts neuroprotection in animal models of traumatic brain injury and multiple sclerosis. However, the role of ABHD6 inhibition on neuropathic pain has not been explored. METHODS Neuropathic pain was induced by chronic constriction injury (CCI) of the mouse sciatic nerve and examined by Hargreaves and Von Frey tests. Activation of inflammatory cells and the production of cytokines and chemokines in the spinal cord dorsal horn, dorsal root ganglion (DRG), and sciatic nerve were assessed by qRT-PCR, enzyme-linked immunosorbent assay (ELISA), and immunohistochemistry. The levels of 2-AG and arachidonic acid (AA) in sciatic nerve were quantified by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). RESULTS Treatment with the selective ABHD6 inhibitor WWL70 significantly alleviated CCI-induced thermal hyperalgesia and mechanical allodynia. Microglia activation, macrophage infiltration, and the production of nociceptive mediators were reduced in the ipsilateral lumbar spinal cord dorsal horn, DRG, and sciatic nerve of WWL70-treated animals. The diminished cytokine and chemokine production is likely due to the inhibitory effect of WWL70 on NF-κB phosphorylation. Surprisingly, the anti-nociceptive and anti-inflammatory effects of WWL70 were not reversed by addition of the cannabinoid receptor antagonists. Treatment with WWL70 did not alter the levels of 2-AG, AA, and the phosphorylation of cytosolic phospholipase A2 (cPLA2), but significantly reduced the production of prostaglandin E2 (PGE2) and the expression of cyclooxygenase-2 (COX-2) and prostaglandin E synthase-2 (PGES2) in the injured sciatic nerve. CONCLUSIONS This study reveals a novel mechanism for the antinociceptive effect of the 2-AG catabolic enzyme ABHD6 inhibitor WWL70. Understanding the interaction between endocannabinoid and eicosanoid pathways might provide a new avenue for the treatment of inflammatory and neuropathic pain.
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Affiliation(s)
- Jie Wen
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Melissa Jones
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Mikiei Tanaka
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Prabhuanand Selvaraj
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Aviva J Symes
- Department of Pharmacology and Molecular Therapeutics, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA.,Neuroscience Program, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Brian Cox
- Department of Pharmacology and Molecular Therapeutics, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA.,Neuroscience Program, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Yumin Zhang
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA. .,Neuroscience Program, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA.
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30
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Nijs J, Loggia ML, Polli A, Moens M, Huysmans E, Goudman L, Meeus M, Vanderweeën L, Ickmans K, Clauw D. Sleep disturbances and severe stress as glial activators: key targets for treating central sensitization in chronic pain patients? Expert Opin Ther Targets 2017; 21:817-826. [DOI: 10.1080/14728222.2017.1353603] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jo Nijs
- Department of physiotherapy, human physiology and anatomy, Pain in Motion International Research Group, Vrije Universiteit Brussel, Brussels, Belgium
- Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium
- Department of Physical Medicine and Physiotherapy, University Hospital Brussels, Brussels, Belgium
| | - Marco L. Loggia
- MGH/HST A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Andrea Polli
- Department of physiotherapy, human physiology and anatomy, Pain in Motion International Research Group, Vrije Universiteit Brussel, Brussels, Belgium
- Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Maarten Moens
- Department of Neurosurgery and Radiology, University Hospital Brussels, Brussels, Belgium
- Department of Manual Therapy, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Eva Huysmans
- Department of physiotherapy, human physiology and anatomy, Pain in Motion International Research Group, Vrije Universiteit Brussel, Brussels, Belgium
- Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Lisa Goudman
- Department of physiotherapy, human physiology and anatomy, Pain in Motion International Research Group, Vrije Universiteit Brussel, Brussels, Belgium
- Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium
- Department of Neurosurgery and Radiology, University Hospital Brussels, Brussels, Belgium
| | - Mira Meeus
- Department of physiotherapy, human physiology and anatomy, Pain in Motion International Research Group, Vrije Universiteit Brussel, Brussels, Belgium
- Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium
- Department of Rehabilitation Sciences and Physiotherapy, University of Antwerp, Antwerp, Belgium
| | - Luc Vanderweeën
- Department of physiotherapy, human physiology and anatomy, Pain in Motion International Research Group, Vrije Universiteit Brussel, Brussels, Belgium
- Department of Physiotherapy, Human Physiology and Anatomy, Faculty of Physical Education & Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium
- Private Practice for Spinal Manual Therapy, Schepdaal-Dilbeek, Belgium
| | - Kelly Ickmans
- Department of physiotherapy, human physiology and anatomy, Pain in Motion International Research Group, Vrije Universiteit Brussel, Brussels, Belgium
- Department of Physical Medicine and Physiotherapy, University Hospital Brussels, Brussels, Belgium
| | - Daniel Clauw
- Chronic Pain and Fatigue Research Center, University of Michigan, Ann Arbor, USA
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31
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Jiang W, Wang Y, Sun W, Zhang M. Morin Suppresses Astrocyte Activation and Regulates Cytokine Release in Bone Cancer Pain Rat Models. Phytother Res 2017; 31:1298-1304. [PMID: 28618070 DOI: 10.1002/ptr.5849] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Revised: 04/27/2017] [Accepted: 05/25/2017] [Indexed: 12/30/2022]
Affiliation(s)
- Wei Jiang
- Shandong Provincial Hospital; Affiliated to Shandong University; No. 324 Jingwuweiqi Road Jinan 250021 Shandong Province China
| | - Ying Wang
- Shandong Provincial Hospital; Affiliated to Shandong University; No. 324 Jingwuweiqi Road Jinan 250021 Shandong Province China
| | - Wei Sun
- Shandong Provincial Hospital; Affiliated to Shandong University; No. 324 Jingwuweiqi Road Jinan 250021 Shandong Province China
| | - Mengyuan Zhang
- Shandong Provincial Hospital; Affiliated to Shandong University; No. 324 Jingwuweiqi Road Jinan 250021 Shandong Province China
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32
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Chen G, Luo X, Qadri MY, Berta T, Ji RR. Sex-Dependent Glial Signaling in Pathological Pain: Distinct Roles of Spinal Microglia and Astrocytes. Neurosci Bull 2017; 34:98-108. [PMID: 28585113 DOI: 10.1007/s12264-017-0145-y] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 03/16/2017] [Indexed: 12/18/2022] Open
Abstract
Increasing evidence suggests that spinal microglia regulate pathological pain in males. In this study, we investigated the effects of several microglial and astroglial modulators on inflammatory and neuropathic pain following intrathecal injection in male and female mice. These modulators were the microglial inhibitors minocycline and ZVEID (a caspase-6 inhibitor) and the astroglial inhibitors L-α-aminoadipate (L-AA, an astroglial toxin) and carbenoxolone (a connexin 43 inhibitor), as well as U0126 (an ERK kinase inhibitor) and D-JNKI-1 (a c-Jun N-terminal kinase inhibitor). We found that spinal administration of minocycline or ZVEID, or Caspase6 deletion, reduced formalin-induced inflammatory and nerve injury-induced neuropathic pain primarily in male mice. In contrast, intrathecal L-AA reduced neuropathic pain but not inflammatory pain in both sexes. Intrathecal U0126 and D-JNKI-1 reduced neuropathic pain in both sexes. Nerve injury caused spinal upregulation of the astroglial markers GFAP and Connexin 43 in both sexes. Collectively, our data confirmed male-dominant microglial signaling but also revealed sex-independent astroglial signaling in the spinal cord in inflammatory and neuropathic pain.
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Affiliation(s)
- Gang Chen
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA. .,Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
| | - Xin Luo
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - M Yawar Qadri
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Temugin Berta
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA.,Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, 45267, USA
| | - Ru-Rong Ji
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA.,Department of Neurobiology, Duke University Medical Center, Durham, NC, 27710, USA
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33
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Li XM, Meng J, Li LT, Guo T, Yang LK, Shi QX, Li XB, Chen Y, Yang Q, Zhao JN. Effect of ZBD-2 on chronic pain, depressive-like behaviors, and recovery of motor function following spinal cord injury in mice. Behav Brain Res 2017; 322:92-99. [PMID: 28108322 PMCID: PMC5339413 DOI: 10.1016/j.bbr.2017.01.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 01/09/2017] [Accepted: 01/12/2017] [Indexed: 02/06/2023]
Abstract
ZBD-2 significantly attenuated the symptoms of chronic SCI-pain and pain-induced depressive-like behaviors. ZBD-2 inhibited the decreases in the expression of synaptic plasticity-related signaling proteins. ZBD-2 reversed chronic, SCI-induced gliocyte activation at the lesion site.
In addition to debilitating sensory and motor deficits, patients with spinal cord injury (SCI) may experience chronic hyperpathic pain (SCI-pain). Recent studies have revealed that translocator protein (TSPO) is involved in repairing neural cells as well as reducing anxiety and depression. However, the role of TSPO in SCI-pain and pain-induced depression remains unknown. The present study aimed to determine the effects of a new TSPO ligand, ZBD-2, on SCI-pain and consequent pain-induced depressive-like behaviors in mice. Treatment with ZBD-2 at either dose significantly attenuated the symptoms of chronic SCI-pain and pain-induced depressive-like behaviors. ZBD-2 reversed SCI-induced elevation of serum corticosterone levels, an index of hyper-activation of the hypothalamic–pituitary–adrenal (HPA) axis. Additionally, administration of ZBD-2 inhibited decreases in the expression of synaptic plasticity-related signaling proteins, including brain-derived neurotrophic factor (BDNF) and cyclic AMP-responsive element binding protein (CREB). Moreover, ZBD-2 administration reversed chronic, SCI-induced gliocyte activation at the lesion site. Therefore, ZBD-2 may improve chronic SCI-pain and pain-induced depressive-like behaviors via suppression of gliocyte activation and restoration of the synaptic plasticity-related signaling systems.
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Affiliation(s)
- Xiao-Ming Li
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Jia Meng
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Lin Tao Li
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Ting Guo
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China
| | - Liu-Kun Yang
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China
| | - Qi-Xin Shi
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China
| | - Xu-Bo Li
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China
| | - Yong Chen
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China.
| | - Qi Yang
- Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, China.
| | - Jian-Ning Zhao
- Department of Orthopedics, Jinling Hospital, Clinical School of Nanjing, Second Military Medical University, Nanjing, 210002, China.
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Abstract
Classically, pain is viewed as being mediated solely by neurons. However, recent research has shown that activated glial cells (astrocytes and microglia) within the spinal cord amplify pain. These nonneuronal cells play a major role in the creation and maintenance of pathological pain. Glia become activated by immune challenges (viral or bacterial infection) and by substances released by neurons within the pain pathway. Activated glia amplify pain by releasing proinflammatory cytokines. Taken together, research findings suggest a novel approach to human pain control that targets glia. In addition, it is likely that such glial-neuronal interactions are not unique to pain, but rather reflect a general rule of sensory processing.
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Affiliation(s)
- Linda R. Watkins
- Department of Psychology and Center for Neuroscience, University of Colorado at Boulder, Boulder, Colorado
| | - Steven F. Maier
- Department of Psychology and Center for Neuroscience, University of Colorado at Boulder, Boulder, Colorado
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35
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Abstract
Substantial evidence has implicated microglia in neuropathic pain. After peripheral nerve injury, microglia in the spinal cord proliferate and increase cell-surface expression of the purinergic receptor P2X4. Activation of P2X4 receptors results in release of brain-derived neurotrophic factor, which acts on neurons to produce disinhibition of dorsal horn neurons which transmit nociceptive information to the brain. Disinhibition of these neurons produces pain hypersensitivity, a hallmark symptom of neuropathic pain. However, elucidating this microglia-neuronal signalling pathway was based on studies using only male rodents. Recent evidence has shown that the role of microglia in pain is sexually dimorphic. Despite similar microglia proliferation in the dorsal horn in both sexes, females do not upregulate P2X4Rs and use a microglia-independent pathway to mediate pain hypersensitivity. Instead, adaptive immune cells, possibly T cells, may mediate pain hypersensitivity in female mice. This profound sex difference highlights the importance of including subjects of both sexes in preclinical pain research.
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36
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Dodds KN, Beckett EAH, Evans SF, Grace PM, Watkins LR, Hutchinson MR. Glial contributions to visceral pain: implications for disease etiology and the female predominance of persistent pain. Transl Psychiatry 2016; 6:e888. [PMID: 27622932 PMCID: PMC5048206 DOI: 10.1038/tp.2016.168] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 07/14/2016] [Accepted: 07/22/2016] [Indexed: 12/27/2022] Open
Abstract
In the central nervous system, bidirectional signaling between glial cells and neurons ('neuroimmune communication') facilitates the development of persistent pain. Spinal glia can contribute to heightened pain states by a prolonged release of neurokine signals that sensitize adjacent centrally projecting neurons. Although many persistent pain conditions are disproportionately common in females, whether specific neuroimmune mechanisms lead to this increased susceptibility remains unclear. This review summarizes the major known contributions of glia and neuroimmune interactions in pain, which has been determined principally in male rodents and in the context of somatic pain conditions. It is then postulated that studying neuroimmune interactions involved in pain attributed to visceral diseases common to females may offer a more suitable avenue for investigating unique mechanisms involved in female pain. Further, we discuss the potential for primed spinal glia and subsequent neurogenic inflammation as a contributing factor in the development of peripheral inflammation, therefore, representing a predisposing factor for females in developing a high percentage of such persistent pain conditions.
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Affiliation(s)
- K N Dodds
- Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, SA, Australia
| | - E A H Beckett
- Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, SA, Australia
| | - S F Evans
- Discipline of Pharmacology, School of Medicine, University of Adelaide, Adelaide, SA, Australia
- Pelvic Pain SA, Norwood, SA, Australia
| | - P M Grace
- Discipline of Pharmacology, School of Medicine, University of Adelaide, Adelaide, SA, Australia
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - L R Watkins
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - M R Hutchinson
- Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, SA, Australia
- ARC Centre of Excellence for Nanoscale BioPhotonics, University of Adelaide, Adelaide, SA, Australia
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DeLeo JA, Tanga FY, Tawfik VL. Neuroimmune Activation and Neuroinflammation in Chronic Pain and Opioid Tolerance/Hyperalgesia. Neuroscientist 2016; 10:40-52. [PMID: 14987447 DOI: 10.1177/1073858403259950] [Citation(s) in RCA: 290] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
One area that has emerged as a promising therapeutic target for the treatment and prevention of chronic pain and opioid tolerance/hyperalgesia is the modulation of the central nervous system (CNS) immunological response that ensues following injury or opioid administration. Broadly defined, central neuroimmune activation involves the activation of cells that interface with the peripheral nervous system and blood. Activation of these cells, as well as parenchymal microglia and astrocytes by injury, opioids, and other stressors, leads to subsequent production of cytokines, cellular adhesion molecules, chemokines, and the expression of surface antigens that enhance a CNS immune cascade. This response can lead to the production of numerous pain mediators that can sensitize and lower the threshold of neuronal firing: the pathologic correlate to central sensitization and chronic pain states. CNS innate immunity and Toll-like receptors, in particular, may be vital players in this orchestrated immune response and may hold the answers to what initiates this complex cascade. The challenge remains in the careful perturbation of injury/opioid-induced neuroimmune activation to down-regulate this process without inhibiting beneficial CNS autoimmunity that subserves neuronal protection following injury.
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Affiliation(s)
- Joyce A DeLeo
- Department of Anesthesiology, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA.
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Abstract
All nervous system cell types can be induced with cytokines or bacterial products to make nitric oxide, at least in culture. The signaling pathways invoked by inducers that result in transcriptional activation of the nitric oxide synthase gene are becoming clear, and modulators of this induction have been discovered. Much suggestive and, recently, more definitive evidence has accumulated for induction of nitric oxide synthase in glial cells in vivo associated with viral infection, as well as in animal models of trauma, ischemia, and autoimmunity. Whether nitric oxide from this source contributes to or limits the attendant conditions is not yet clear. The Neuroscientist 2:90-99, 1996
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Affiliation(s)
| | - Dana Grzybicki
- Department of Pathology University of Iowa College of
Medicine Iowa City, Iowa
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39
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Liu B, Liu X, Tang SJ. Interactions of Opioids and HIV Infection in the Pathogenesis of Chronic Pain. Front Microbiol 2016; 7:103. [PMID: 26903982 PMCID: PMC4748029 DOI: 10.3389/fmicb.2016.00103] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 01/19/2016] [Indexed: 12/30/2022] Open
Abstract
Over 50% of HIV-1/AIDS patients suffer chronic pain. Currently, opioids are the cornerstone medications for treating severe pain in these patients. Ironically, emerging clinical data indicates that repeated use of opiate pain medicines might in fact heighten the chronic pain states in HIV patients. Both laboratory-based and clinical studies strongly suggest that opioids exacerbate the detrimental effects of HIV-1 infection on the nervous system, both on neurons and glia. The combination of opioids and HIV-1infection may promote the damage of neurons, including those in the pain sensory and transmission pathway, by activating both caspase-dependent and caspase-independent pro-apoptotic pathways. In addition, the opiate-HIV-1 interaction may also cause widespread disturbance of glial function and elicit glial-derived pro-inflammatory responses that dysregulate neuronal function. The deregulation of neuron-glia cross-talk that occurs with the combination of HIV-1 and opioids appears to play an important role in the development of the pathological pain state. In this article, we wish to provide an overview of the potential molecular and cellular mechanisms by which opioids may interact with HIV-1 to cause neurological problems, especially in the context of HIV-associated pathological pain. Elucidating the underlying mechanisms will help researchers and clinicians to understand how chronic use of opioids for analgesia enhances HIV-associated pain. It will also assist in optimizing therapeutic approaches to prevent or minimize this significant side effect of opiate analgesics in pain management for HIV patients.
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Affiliation(s)
- Bolong Liu
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, GalvestonTX, USA; Department of Urology, Third Affiliated Hospital of Sun Yat-Sen UniversityGuangzhou, China
| | - Xin Liu
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston TX, USA
| | - Shao-Jun Tang
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston TX, USA
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40
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Permpoonputtana K, Porter JE, Govitrapong P. Calcitonin gene-related peptide mediates an inflammatory response in Schwann cells via cAMP-dependent ERK signaling cascade. Life Sci 2015; 144:19-25. [PMID: 26596264 DOI: 10.1016/j.lfs.2015.11.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 10/14/2015] [Accepted: 11/16/2015] [Indexed: 12/20/2022]
Abstract
AIMS Calcitonin gene-related peptides (CGRP), an endogenous neuropeptide, play an important role in the development of neuroinflammation by acting upon its receptor. The CGRP receptor immunoreactivity was identified on Schwann cells. However the effects of CGRP on Schwann cells are unknown and the exact signaling mechanisms associated with CGRP receptor activation related to Schwann cells inflammatory responses are not well understood. We investigated the effect of CGRP on CGRP receptor activation mediates a proinflammatory signaling response in Schwann cells. MAIN METHODS CGRP-induced ERK-MAPK phosphorylation and proinflammatory cytokines, interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor (TNF-α) expressions were measured by immune blotting. We also used specific antagonist and inhibitors to confirm the exactly signaling pathway including CGRP (8-37), SQ 22536 and H-89. KEY FINDINGS Treatment with CGRP demonstrated a significant generation of IL-1β and IL-6 but not in the level of TNF-α. In addition, there was a temporal increase in the activated form of ERK caused by CGRP that was prevented after pretreatment with CGRP (8-37), SQ 22536 and H-89. Furthermore, use of the CGRP (8-37), ERK inhibitor PD 98059, SQ 22536 or H-89 abolished the CGRP mediated increase in IL-1β. SIGNIFICANCE This investigation provides evidence for a novel CGRP activation on Schwann cells that mediates inflammatory response by increasing of IL-1β and IL-6 expression. CGRP activates the cAMP-PKA-ERK signaling cascade leading to IL-1β production. These results support the notion that CGRP may play a direct role to initiate inflammatory processes in the peripheral nervous system.
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Affiliation(s)
- Kannika Permpoonputtana
- Occupational Therapy Division, Faculty of Physical Therapy, Mahidol University, Nakornpathom 73170, Thailand
| | - James E Porter
- Department of Pharmacology, Physiology, and Therapeutics, University of North Dakota, Grand Forks, ND 58202, USA
| | - Piyarat Govitrapong
- Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University, Nakornpathom, Thailand; Center for Neuroscience and Department of Pharmacology, Faculty of Science, Mahidol University, Bangkok, Thailand.
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Dynamic weight bearing is an efficient and predictable method for evaluation of arthritic nociception and its pathophysiological mechanisms in mice. Sci Rep 2015; 5:14648. [PMID: 26511791 PMCID: PMC4625149 DOI: 10.1038/srep14648] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 09/02/2015] [Indexed: 12/20/2022] Open
Abstract
The assessment of articular nociception in experimental animals is a challenge because available methods are limited and subject to investigator influence. In an attempt to solve this problem, the purpose of this study was to establish the use of dynamic weight bearing (DWB) as a new device for evaluating joint nociception in an experimental model of antigen-induced arthritis (AIA) in mice. AIA was induced in Balb/c and C57BL/6 mice, and joint nociception was evaluated by DWB. Western Blotting and real-time PCR were used to determine protein and mRNA expression, respectively. DWB detected a dose- and time-dependent increase in joint nociception during AIA and was able to detect the dose-response effects of different classes of analgesics. Using DWB, it was possible to evaluate the participation of spinal glial cells (microglia and astrocytes) and cytokines (IL-1β and TNFα) for the genesis of joint nociception during AIA. In conclusion, the present results indicated that DWB is an effective, objective and predictable test to study both the pathophysiological mechanisms involved in arthritic nociception in mice and for evaluating novel analgesic drugs against arthritis.
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Alfonso Romero-Sandoval E, Sweitzer S. Nonneuronal central mechanisms of pain: glia and immune response. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 131:325-58. [PMID: 25744678 DOI: 10.1016/bs.pmbts.2014.11.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The role of central glial cells in the mechanisms underlying pain has been intensively studied in the last two decades. Most studies on glia and pain focused on the potential detrimental role of glial cells following noxious stimulus/insults manifested as an "activation" or a "reactive" state (increase in glial marker expression and production of proinflammatory/nociceptive molecules). Therefore, "activated" or "reactive" glial cells became a target for the future generation of drugs to treat chronic pain. Several glial modulators that reduce the activation of glial cells have shown great efficacy in multiple animal (rodents mostly) models of pain (acute, subacute, chronic, inflammatory, neuropathic, surgical, etc.). These encouraging findings inspired clinical trials that have been completed in the last 5 years. Unfortunately, all clinical trials with these glial modulators have failed to demonstrate efficacy for the treatment of pain. New lines of investigation and elegant experimental designs are shedding light on alternative glial functions, which demonstrate that "glial reactivity" is not necessarily deleterious in some pathological conditions. New strategies to validate findings through our current animal models are necessary to enhance the translational value of our preclinical studies. Also, more studies using human subjects would enhance our understanding of glial cells in the context of pain. This chapter explores the available literature to objectively ponder the potential role of glial cells in human pain conditions.
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Affiliation(s)
- E Alfonso Romero-Sandoval
- Department of Pharmaceutical and Administrative Sciences, Presbyterian College School of Pharmacy, Clinton, South Carolina, USA.
| | - Sarah Sweitzer
- Department of Pharmaceutical and Administrative Sciences, Presbyterian College School of Pharmacy, Clinton, South Carolina, USA
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Consalvi S, Alfonso S, Di Capua A, Poce G, Pirolli A, Sabatino M, Ragno R, Anzini M, Sartini S, La Motta C, Di Cesare Mannelli L, Ghelardini C, Biava M. Synthesis, biological evaluation and docking analysis of a new series of methylsulfonyl and sulfamoyl acetamides and ethyl acetates as potent COX-2 inhibitors. Bioorg Med Chem 2015; 23:810-20. [DOI: 10.1016/j.bmc.2014.12.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 12/14/2014] [Accepted: 12/17/2014] [Indexed: 01/01/2023]
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Loggia ML, Chonde DB, Akeju O, Arabasz G, Catana C, Edwards RR, Hill E, Hsu S, Izquierdo-Garcia D, Ji RR, Riley M, Wasan AD, Zürcher NR, Albrecht DS, Vangel MG, Rosen BR, Napadow V, Hooker JM. Evidence for brain glial activation in chronic pain patients. ACTA ACUST UNITED AC 2015; 138:604-15. [PMID: 25582579 DOI: 10.1093/brain/awu377] [Citation(s) in RCA: 337] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Although substantial evidence has established that microglia and astrocytes play a key role in the establishment and maintenance of persistent pain in animal models, the role of glial cells in human pain disorders remains unknown. Here, using the novel technology of integrated positron emission tomography-magnetic resonance imaging and the recently developed radioligand (11)C-PBR28, we show increased brain levels of the translocator protein (TSPO), a marker of glial activation, in patients with chronic low back pain. As the Ala147Thr polymorphism in the TSPO gene affects binding affinity for (11)C-PBR28, nine patient-control pairs were identified from a larger sample of subjects screened and genotyped, and compared in a matched-pairs design, in which each patient was matched to a TSPO polymorphism-, age- and sex-matched control subject (seven Ala/Ala and two Ala/Thr, five males and four females in each group; median age difference: 1 year; age range: 29-63 for patients and 28-65 for controls). Standardized uptake values normalized to whole brain were significantly higher in patients than controls in multiple brain regions, including thalamus and the putative somatosensory representations of the lumbar spine and leg. The thalamic levels of TSPO were negatively correlated with clinical pain and circulating levels of the proinflammatory citokine interleukin-6, suggesting that TSPO expression exerts pain-protective/anti-inflammatory effects in humans, as predicted by animal studies. Given the putative role of activated glia in the establishment and or maintenance of persistent pain, the present findings offer clinical implications that may serve to guide future studies of the pathophysiology and management of a variety of persistent pain conditions.
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Affiliation(s)
- Marco L Loggia
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA 2 Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02155, USA
| | - Daniel B Chonde
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Oluwaseun Akeju
- 3 Department of Anesthesia, Critical Care and Pain Medicine, MGH/HMS, Boston, MA 02114, USA
| | - Grae Arabasz
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Ciprian Catana
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Robert R Edwards
- 2 Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02155, USA 4 Department of Psychiatry, Brigham and Women's Hospital, HMS, Boston, MA 02155, USA
| | - Elena Hill
- 5 Tufts University School of Medicine, Boston, MA 02111, USA
| | - Shirley Hsu
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - David Izquierdo-Garcia
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Ru-Rong Ji
- 2 Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02155, USA 6 Departments of Anesthesiology and Neurobiology, Duke University Medical Center, Durham, NC 27705, USA
| | - Misha Riley
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Ajay D Wasan
- 2 Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02155, USA 4 Department of Psychiatry, Brigham and Women's Hospital, HMS, Boston, MA 02155, USA 7 Departments of Anesthesiology and Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15206, USA
| | - Nicole R Zürcher
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Daniel S Albrecht
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Mark G Vangel
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Bruce R Rosen
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA 8 Division of Health Sciences and Technology, Harvard-Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Vitaly Napadow
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA 2 Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02155, USA 9 Department of Biomedical Engineering, Kyung Hee University, Seoul 130-872, Republic of Korea
| | - Jacob M Hooker
- 1 MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
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Old EA, Clark AK, Malcangio M. The role of glia in the spinal cord in neuropathic and inflammatory pain. Handb Exp Pharmacol 2015; 227:145-170. [PMID: 25846618 DOI: 10.1007/978-3-662-46450-2_8] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Chronic pain, both inflammatory and neuropathic, is a debilitating condition in which the pain experience persists after the painful stimulus has resolved. The efficacy of current treatment strategies using opioids, NSAIDS and anticonvulsants is limited by the extensive side effects observed in patients, underlining the necessity for novel therapeutic targets. Preclinical models of chronic pain have recently provided evidence for a critical role played by glial cells in the mechanisms underlying the chronicity of pain, both at the site of damage in the periphery and in the dorsal horn of the spinal cord. Here microglia and astrocytes respond to the increased input from the periphery and change morphology, increase in number and release pro-nociceptive mediators such as ATP, cytokines and chemokines. These gliotransmitters can sensitise neurons by activation of their cognate receptors thereby contributing to central sensitization which is fundamental for the generation of allodynia, hyperalgesia and spontaneous pain.
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Affiliation(s)
- Elizabeth Amy Old
- Wolfson Centre for Age Related Diseases, King's College London, London, UK
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46
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Heiman A, Pallottie A, Heary RF, Elkabes S. Toll-like receptors in central nervous system injury and disease: a focus on the spinal cord. Brain Behav Immun 2014; 42:232-45. [PMID: 25063708 DOI: 10.1016/j.bbi.2014.06.203] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/17/2014] [Accepted: 06/28/2014] [Indexed: 12/12/2022] Open
Abstract
Toll-like receptors (TLRs) are best known for recognizing pathogens and initiating an innate immune response to protect the host. However, they also detect tissue damage and induce sterile inflammation upon the binding of endogenous ligands released by stressed or injured cells. In addition to immune system-related cells, TLRs have been identified in central nervous system (CNS) neurons and glial subtypes including microglia, astrocytes and oligodendrocytes. Direct and indirect effects of TLR ligands on neurons and glial subtypes have been documented in vitro. Likewise, the effects of TLR ligands have been demonstrated in vivo using animal models of CNS trauma and disease including spinal cord injury (SCI), amyotrophic lateral sclerosis (ALS) and neuropathic pain. The indirect effects are most likely mediated via microglia or immune system cells that infiltrate the diseased or injured CNS. Despite considerable progress over the past decade, the role of TLRs in the physiological and pathological function of the spinal cord remains inadequately defined. Published reports collectively highlight TLRs as promising targets for therapeutic interventions in spinal cord pathology. The findings also underscore the complexity of TLR-mediated mechanisms and the necessity for further research in this field. The goals of the current review are to recapitulate the studies that investigated the role of TLRs in the spinal cord, to discuss potential future research directions, and to examine some of the challenges associated with pre-clinical studies pertinent to TLRs in the injured or diseased spinal cord.
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Affiliation(s)
- Adee Heiman
- Reynolds Family Spine Laboratory, Department of Neurological Surgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States
| | - Alexandra Pallottie
- Reynolds Family Spine Laboratory, Department of Neurological Surgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States; Graduate School of Biomedical Sciences, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States
| | - Robert F Heary
- Reynolds Family Spine Laboratory, Department of Neurological Surgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States
| | - Stella Elkabes
- Reynolds Family Spine Laboratory, Department of Neurological Surgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States.
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Grau JW, Huie JR, Lee KH, Hoy KC, Huang YJ, Turtle JD, Strain MM, Baumbauer KM, Miranda RM, Hook MA, Ferguson AR, Garraway SM. Metaplasticity and behavior: how training and inflammation affect plastic potential within the spinal cord and recovery after injury. Front Neural Circuits 2014; 8:100. [PMID: 25249941 PMCID: PMC4157609 DOI: 10.3389/fncir.2014.00100] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 07/31/2014] [Indexed: 12/30/2022] Open
Abstract
Research has shown that spinal circuits have the capacity to adapt in response to training, nociceptive stimulation and peripheral inflammation. These changes in neural function are mediated by physiological and neurochemical systems analogous to those that support plasticity within the hippocampus (e.g., long-term potentiation and the NMDA receptor). As observed in the hippocampus, engaging spinal circuits can have a lasting impact on plastic potential, enabling or inhibiting the capacity to learn. These effects are related to the concept of metaplasticity. Behavioral paradigms are described that induce metaplastic effects within the spinal cord. Uncontrollable/unpredictable stimulation, and peripheral inflammation, induce a form of maladaptive plasticity that inhibits spinal learning. Conversely, exposure to controllable or predictable stimulation engages a form of adaptive plasticity that counters these maladaptive effects and enables learning. Adaptive plasticity is tied to an up-regulation of brain derived neurotrophic factor (BDNF). Maladaptive plasticity is linked to processes that involve kappa opioids, the metabotropic glutamate (mGlu) receptor, glia, and the cytokine tumor necrosis factor (TNF). Uncontrollable nociceptive stimulation also impairs recovery after a spinal contusion injury and fosters the development of pain (allodynia). These adverse effects are related to an up-regulation of TNF and a down-regulation of BDNF and its receptor (TrkB). In the absence of injury, brain systems quell the sensitization of spinal circuits through descending serotonergic fibers and the serotonin 1A (5HT 1A) receptor. This protective effect is blocked by surgical anesthesia. Disconnected from the brain, intracellular Cl- concentrations increase (due to a down-regulation of the cotransporter KCC2), which causes GABA to have an excitatory effect. It is suggested that BDNF has a restorative effect because it up-regulates KCC2 and re-establishes GABA-mediated inhibition.
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Affiliation(s)
- James W Grau
- Cellular and Behavioral Neuroscience, Department of Psychology, Texas A&M University, College Station TX, USA
| | - J Russell Huie
- Department of Neurological Surgery, Brain and Spinal Injury Center, University of California San Francisco San Francisco, CA, USA
| | - Kuan H Lee
- Cellular and Behavioral Neuroscience, Department of Psychology, Texas A&M University, College Station TX, USA
| | - Kevin C Hoy
- Department of Neurosciences, MetroHealth Medical Center and Case Western Reserve University Cleveland, OH, USA
| | - Yung-Jen Huang
- Cellular and Behavioral Neuroscience, Department of Psychology, Texas A&M University, College Station TX, USA
| | - Joel D Turtle
- Cellular and Behavioral Neuroscience, Department of Psychology, Texas A&M University, College Station TX, USA
| | - Misty M Strain
- Cellular and Behavioral Neuroscience, Department of Psychology, Texas A&M University, College Station TX, USA
| | | | - Rajesh M Miranda
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center Bryan, TX, USA
| | - Michelle A Hook
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center Bryan, TX, USA
| | - Adam R Ferguson
- Department of Neurological Surgery, Brain and Spinal Injury Center, University of California San Francisco San Francisco, CA, USA
| | - Sandra M Garraway
- Department of Physiology, Emory University School of Medicine Atlanta, GA, USA
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48
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Komatsu T, Katsuyama S, Mizoguchi H, Sakurada C, Tsuzuki M, Sakurada S, Sakurada T. Spinal ERK2 activation through δ2-opioid receptors contributes to nociceptive behavior induced by intrathecal injection of leucine-enkephalin. Peptides 2014; 54:131-9. [PMID: 24480726 DOI: 10.1016/j.peptides.2014.01.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 01/07/2014] [Accepted: 01/08/2014] [Indexed: 11/15/2022]
Abstract
Intrathecal (i.t.) injection of leucine-enkephalin (Leu-ENK), co-administered with peptidase inhibitors, phosphoramidon (an endopeptidase 24.11 inhibitor), and bestatin (a general aminopeptidase inhibitor), produced behaviors consisting of the biting and/or licking of the hindpaw and the tail along with hindlimb scratching directed toward the flank, which peaked at 10-15 min after an injection. This characteristic behavior was not observed in mice treated with i.t. Leu-ENK alone. We also investigated the effect of the extracellular signal-regulated kinase (ERK) in spinal processing of nociception induced by i.t. co-administration of Leu-ENK with phospharamidon and bestatin. Western blot analysis of phospho-ERK (pERK) showed a significant increase of pERK2 in the lumbar spinal cord in response to i.t. Leu-ENK co-injected with peptidase inhibitors. The MAP kinase-ERK inhibitor, U0126 dose-dependently attenuated the nociceptive behavior and spinal ERK activation to i.t. Leu-ENK co-injected with peptidase inhibitors. Furthermore, the nociceptive behavior and spinal ERK activation evoked by i.t. Leu-ENK in combination with peptidase inhibitors were inhibited by co-administration of the non-selective δ-opioid receptor antagonist, naltrindole, the selective δ2-opioid receptor antagonist, naltriben, the non-competitive N-methyl-D-aspartate (NMDA) antagonist, MK-801 or the non-selective nitric oxide synthase inhibitor, L-NAME, the selective nNOS inhibitor, N(ω)-propyl-L-arginine or the selective iNOS inhibitor, W1400, but not by the selective δ1-receptor antagonist, BNTX (7-benzylidenenaltrexone). These results suggest that spontaneous nociceptive behaviors produced by i.t. co-administration of Leu-ENK with peptidase inhibitors may be induced by an activation of the glutamate-NO-ERK pathway through the δ2-opioid receptor in the dorsal spinal cord.
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MESH Headings
- Animals
- Arginine/analogs & derivatives
- Arginine/pharmacology
- Behavior, Animal/drug effects
- Butadienes/pharmacology
- Enkephalin, Leucine/administration & dosage
- Enkephalin, Leucine/pharmacology
- Enzyme Activation/drug effects
- Glycopeptides/pharmacology
- Injections, Spinal
- Leucine/analogs & derivatives
- Leucine/pharmacology
- Male
- Mice, Inbred Strains
- Mitogen-Activated Protein Kinase 1/metabolism
- NG-Nitroarginine Methyl Ester/pharmacology
- Naltrexone/analogs & derivatives
- Naltrexone/pharmacology
- Nitric Oxide Synthase/antagonists & inhibitors
- Nitriles/pharmacology
- Nociception/drug effects
- Protease Inhibitors/pharmacology
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/metabolism
- Spinal Cord/drug effects
- Spinal Cord/metabolism
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Affiliation(s)
- Takaaki Komatsu
- Department of Pharmacology, Daiichi College of Pharmaceutical Sciences, 22-1 Tamagawa-cho, Minami-ku, Fukuoka 815-8511, Japan
| | - Soh Katsuyama
- Department of Clinical Pharmaceutics, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
| | - Hirokazu Mizoguchi
- Department of Physiology and Anatomy, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
| | - Chikai Sakurada
- Department of Biochemistry, Nihon Pharmaceutical University, 10281 Komuro, Ina-Machi, Kitaadachi-gun, Saitama 362-0806, Japan
| | - Minoru Tsuzuki
- Department of Biochemistry, Nihon Pharmaceutical University, 10281 Komuro, Ina-Machi, Kitaadachi-gun, Saitama 362-0806, Japan
| | - Shinobu Sakurada
- Department of Physiology and Anatomy, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
| | - Tsukasa Sakurada
- Department of Pharmacology, Daiichi College of Pharmaceutical Sciences, 22-1 Tamagawa-cho, Minami-ku, Fukuoka 815-8511, Japan.
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Lee J, Favorov OV, Tommerdahl M, Lee CJ, Whitsel BL. Attenuated Glial K(+) Clearance Contributes to Long-Term Synaptic Potentiation Via Depolarizing GABA in Dorsal Horn Neurons of Rat Spinal Cord. Exp Neurobiol 2014; 23:53-64. [PMID: 24737940 PMCID: PMC3984957 DOI: 10.5607/en.2014.23.1.53] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 03/05/2014] [Accepted: 03/05/2014] [Indexed: 11/19/2022] Open
Abstract
It has been reported that long-term enhancement of superficial dorsal horn (DHs) excitatory synaptic transmission underlies central sensitization, secondary hyperalgesia, and persistent pain. We tested whether impaired clearance of K(+) and glutamate by glia in DHs may contribute to initiation and maintenance of the CNS pain circuit and sensorimotor abnormalities. Transient exposure of the spinal cord slice to fluorocitrate (FC) is shown to be accompanied by a protracted decrease of the DHs optical response to repetitive electrical stimulation of the ipsilateral dorsal root, and by a similarly protracted increase in the postsynaptic response of the DHs like LTP. It also is shown that LTPFC does not occur in the presence of APV, and becomes progressively smaller as [K(+)]o in the perfusion solution decreased from 3.0 mM to 0.0 mM. Interestingly LTPFC is reduced by bath application of Bic. Whole-cell patch recordings were carried out to evaluate the effects of FC on the response of DHs neurons to puffer-applied GABA. The observations reveal that transient exposure to FC is reliably accompanied by a prolonged (>1 hr) depolarizing shift of the equilibrium potential for the DHs neuron transmembrane ionic currents evoked by GABA. Considered collectively, the findings demonstrate that LTPFC involves (1) elevation of [K(+)]o in the DHs, (2) NMDAR activation, and (3) conversion of the effect of GABA on DHs neurons from inhibition to excitation. It is proposed that a transient impairment of astrocyte energy production can trigger the cascade of dorsal horn mechanisms that underlies hyperalgesia and persistent pain.
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Affiliation(s)
- Jaekwang Lee
- Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. ; WCI Center for Functional Connectomics, Institute of Science and Technology (KIST), Seoul, Korea
| | - Oleg V Favorov
- Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mark Tommerdahl
- Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - C Justin Lee
- WCI Center for Functional Connectomics, Institute of Science and Technology (KIST), Seoul, Korea. ; KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Korea
| | - Barry L Whitsel
- Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. ; Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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Sato KL, Johanek LM, Sanada LS, Sluka KA. Spinal cord stimulation reduces mechanical hyperalgesia and glial cell activation in animals with neuropathic pain. Anesth Analg 2014; 118:464-472. [PMID: 24361846 DOI: 10.1213/ane.0000000000000047] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Spinal cord stimulation (SCS) is commonly used for neuropathic pain; the optimal variables and mechanisms of action are unclear. We tested whether modulation of SCS variables improved analgesia in animals with neuropathic pain by comparing 6-hour vs 30-minute duration and 50%, 75%, or 90% motor threshold (MT) intensity (amplitude). Furthermore, we examined whether maximally effective SCS reduced glial activation in the spinal cord in neuropathic animals. METHODS Sprague-Dawley rats received the spared nerve injury model and were implanted with an epidural SCS lead. Animals were tested for mechanical withdrawal threshold of the paw before and 2 weeks after spared nerve injury, before and after SCS daily for 4 days, and 1, 4, and 9 days after SCS. Spinal cords were examined for the effects of SCS on glial cell activation. RESULTS The mechanical withdrawal threshold decreased, and glial immunoreactivity increased 2 weeks after spared nerve injury. For duration, 6-hour SCS significantly increased the mechanical withdrawal threshold when compared with 30-minute SCS or sham SCS; 30-minute SCS was greater than sham SCS. For intensity (amplitude), 90% MT SCS significantly increased the withdrawal threshold when compared with 75% MT SCS, 50% MT SCS, and sham SCS. Both 4 and 60 Hz SCS decreased glial activation (GFAP, MCP-1, and OX-42) in the spinal cord dorsal horn when compared with sham. CONCLUSIONS Six-hour duration SCS with 90% MT showed the largest increase in mechanical withdrawal threshold, suggesting that the variables of stimulation are important for clinical effectiveness. One potential mechanism for SCS may be to reduce glial activation at the level of the spinal cord.
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Affiliation(s)
- Karina L Sato
- From the Department of Physical Therapy, University of Iowa, Iowa City, Iowa; and Medtronic, Minneapolis, Minnesota
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