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Alexander SN, Reed OA, Burton MD. Spinal cord microglia drive sex differences in ethanol-mediated PGE2-induced allodynia. Brain Behav Immun 2024:S0889-1591(24)00549-X. [PMID: 39147173 DOI: 10.1016/j.bbi.2024.08.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 08/09/2024] [Accepted: 08/11/2024] [Indexed: 08/17/2024] Open
Abstract
The mechanisms of how long-term alcohol use can lead to persistent pain pathology are unclear. Understanding how earlier events of short-term alcohol use can lower the threshold of non-painful stimuli, described as allodynia could prove prudent to understand important initiating mechanisms. Previously, we observed that short-term low-dose alcohol intake induced female-specific allodynia and increased microglial activation in the spinal cord dorsal horn. Other literature describes how chronic ethanol exposure activates Toll-like receptor 4 (TLR4) to initiate inflammatory responses. TLR4 is expressed on many cell types, and we aimed to investigate whether TLR4 on microglia is sufficient to potentiate allodynia during a short-term/low-dose alcohol paradigm. Our study used a novel genetic model where TLR4 expression is removed from the entire body by introducing a floxed transcriptional blocker (TLR4-null background (TLR4LoxTB)), then restricted to microglia by breeding TLR4LoxTB animals with Cx3CR1:CreERT2 animals. As previously reported, after 14 days of ethanol administration alone, we observed no increased pain behavior. However, we observed significant priming effects 3 h post intraplantar injection of a subthreshold dose of prostaglandin E2 (PGE2) in wild-type and microglia-TLR4 restricted female mice. We also observed a significant female-specific shift to pro-inflammatory phenotype and morphological changes in microglia of the lumbar dorsal horn. Investigations in pain priming-associated neuronal subtypes showed an increase of c-Fos and FosB activity in PKCγ interneurons in the dorsal horn of female mice directly corresponding to increased microglial activity. This study uncovers cell- and female-specific roles of TLR4 in sexual dimorphisms in pain induction among non-pathological drinkers.
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Affiliation(s)
- Shevon N Alexander
- Neuroimmunology and Behavior Lab (NIB), Department of Neuroscience, School of Behavioral and Brain Science, Center for Advanced Pain Studies (CAPS), University of Texas at Dallas, Richardson, TX, USA
| | - Olivia A Reed
- Neuroimmunology and Behavior Lab (NIB), Department of Neuroscience, School of Behavioral and Brain Science, Center for Advanced Pain Studies (CAPS), University of Texas at Dallas, Richardson, TX, USA
| | - Michael D Burton
- Neuroimmunology and Behavior Lab (NIB), Department of Neuroscience, School of Behavioral and Brain Science, Center for Advanced Pain Studies (CAPS), University of Texas at Dallas, Richardson, TX, USA.
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2
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Mogil JS, Parisien M, Esfahani SJ, Diatchenko L. Sex differences in mechanisms of pain hypersensitivity. Neurosci Biobehav Rev 2024; 163:105749. [PMID: 38838876 DOI: 10.1016/j.neubiorev.2024.105749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/23/2024] [Accepted: 06/02/2024] [Indexed: 06/07/2024]
Abstract
The introduction of sex-as-a-biological-variable policies at funding agencies around the world has led to an explosion of very recent observations of sex differences in the biology underlying pain. This review considers evidence of sexually dimorphic mechanisms mediating pain hypersensitivity, derived from modern assays of persistent pain in rodent animal models. Three well-studied findings are described in detail: the male-specific role of spinal cord microglia, the female-specific role of calcitonin gene-related peptide (CGRP), and the female-specific role of prolactin and its receptor. Other findings of sex-specific molecular involvement in pain are subjected to pathway analyses and reveal at least one novel hypothesis: that females may preferentially use Th1 and males Th2 T cell activity to mediate chronic pain.
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Affiliation(s)
- Jeffrey S Mogil
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC H3A 1B1, Canada.
| | - Marc Parisien
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC H3A 1B1, Canada
| | - Sahel J Esfahani
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC H3A 1B1, Canada
| | - Luda Diatchenko
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC H3A 1B1, Canada
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3
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Liu X, Yang W, Zhu C, Sun S, Yang B, Wu S, Wang L, Liu Z, Ge Z. TLR2 Mediates Microglial Activation and Contributes to Central Sensitization in a Recurrent Nitroglycerin-induced Chronic Migraine Model. Mol Neurobiol 2024; 61:3697-3714. [PMID: 38008889 DOI: 10.1007/s12035-023-03781-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 11/06/2023] [Indexed: 11/28/2023]
Abstract
Central sensitization is an important pathophysiological mechanism underlying chronic migraine (CM). Previous studies have shown that microglial activation and subsequent inflammation in the trigeminal nucleus caudalis (TNC) contribute to central sensitization. Toll-like receptor 2 (TLR2) is a receptor expressed on the membrane of microglia and participates in central sensitization in inflammatory and chronic pain; however, its role in CM is unclear. Therefore, this study investigated TLR2 involvement in CM in detail. Mice treated with recurrent nitroglycerin (NTG) were used as a CM model. Hyperalgesia was assessed using a 50% paw mechanical threshold and a 50% periorbital threshold on a Von Frey filament pain meter. Western blotting and immunofluorescence analyses were used to detect the expression of TLR2, microglia, c-fos and CGRP in TNC. The expression of inflammatory factors (IL-6, IL-1β、 IL-10、TNF-α and IFN-β1) was detected using quantitative real-time polymerase chain reaction (qRT-PCR). A selective TLR2 antagonist (C29) was systematically administered to observe its effect on hyperalgesia, microglia activation and the expression of c-fos, CGRP and inflammatory factors. Recurrent administration of NTG resulted in acute and chronic hypersensitivity, accompanied by upregulation of TLR2 expression and microglial activation in TNC. C29 partially inhibited pain hypersensitivity. C29 suppressed microglial activation induced by NTG administration. Inhibition of TLR2 reduced the expression of c-fos and CGRP in TNC after NTG treatment. C29 inhibited the expression of inflammatory mediators in TNC. These data showed that microglial TLR2 plays a critical role in the pathogenesis of CM by regulating microglial activation in TNC.
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Affiliation(s)
- Xuejiao Liu
- Department of Neurology, Lanzhou University Second Hospital, Lanzhou, 730030, Gansu, China
| | - Wenping Yang
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Chenlu Zhu
- Department of Neurology, Lanzhou University Second Hospital, Lanzhou, 730030, Gansu, China
| | - Songtang Sun
- Department of Neurology, Lanzhou University Second Hospital, Lanzhou, 730030, Gansu, China
| | - Bin Yang
- Department of Neurology, Lanzhou University Second Hospital, Lanzhou, 730030, Gansu, China
| | - Shouyi Wu
- Department of Neurology, Lanzhou University Second Hospital, Lanzhou, 730030, Gansu, China
| | - Longde Wang
- Expert Workstation of Academician Wang Longde, Lanzhou University Second Hospital, Lanzhou, 730030, Gansu, China
| | - Zhiyan Liu
- Department of Neurology, Lanzhou University Second Hospital, Lanzhou, 730030, Gansu, China.
| | - Zhaoming Ge
- Department of Neurology, Lanzhou University Second Hospital, Lanzhou, 730030, Gansu, China.
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Balan I, Boero G, Chéry SL, McFarland MH, Lopez AG, Morrow AL. Neuroactive Steroids, Toll-like Receptors, and Neuroimmune Regulation: Insights into Their Impact on Neuropsychiatric Disorders. Life (Basel) 2024; 14:582. [PMID: 38792602 PMCID: PMC11122352 DOI: 10.3390/life14050582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 04/18/2024] [Accepted: 04/28/2024] [Indexed: 05/26/2024] Open
Abstract
Pregnane neuroactive steroids, notably allopregnanolone and pregnenolone, exhibit efficacy in mitigating inflammatory signals triggered by toll-like receptor (TLR) activation, thus attenuating the production of inflammatory factors. Clinical studies highlight their therapeutic potential, particularly in conditions like postpartum depression (PPD), where the FDA-approved compound brexanolone, an intravenous formulation of allopregnanolone, effectively suppresses TLR-mediated inflammatory pathways, predicting symptom improvement. Additionally, pregnane neurosteroids exhibit trophic and anti-inflammatory properties, stimulating the production of vital trophic proteins and anti-inflammatory factors. Androstane neuroactive steroids, including estrogens and androgens, along with dehydroepiandrosterone (DHEA), display diverse effects on TLR expression and activation. Notably, androstenediol (ADIOL), an androstane neurosteroid, emerges as a potent anti-inflammatory agent, promising for therapeutic interventions. The dysregulation of immune responses via TLR signaling alongside reduced levels of endogenous neurosteroids significantly contributes to symptom severity across various neuropsychiatric disorders. Neuroactive steroids, such as allopregnanolone, demonstrate efficacy in alleviating symptoms of various neuropsychiatric disorders and modulating neuroimmune responses, offering potential intervention avenues. This review emphasizes the significant therapeutic potential of neuroactive steroids in modulating TLR signaling pathways, particularly in addressing inflammatory processes associated with neuropsychiatric disorders. It advances our understanding of the complex interplay between neuroactive steroids and immune responses, paving the way for personalized treatment strategies tailored to individual needs and providing insights for future research aimed at unraveling the intricacies of neuropsychiatric disorders.
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Affiliation(s)
- Irina Balan
- Bowles Center for Alcohol Studies, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (I.B.); (S.L.C.); (M.H.M.); (A.G.L.)
- Department of Psychiatry, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Giorgia Boero
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710, USA;
| | - Samantha Lucenell Chéry
- Bowles Center for Alcohol Studies, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (I.B.); (S.L.C.); (M.H.M.); (A.G.L.)
- Neuroscience Curriculum, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Minna H. McFarland
- Bowles Center for Alcohol Studies, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (I.B.); (S.L.C.); (M.H.M.); (A.G.L.)
- Neuroscience Curriculum, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Alejandro G. Lopez
- Bowles Center for Alcohol Studies, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (I.B.); (S.L.C.); (M.H.M.); (A.G.L.)
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - A. Leslie Morrow
- Bowles Center for Alcohol Studies, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (I.B.); (S.L.C.); (M.H.M.); (A.G.L.)
- Department of Psychiatry, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Pharmacology, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Rodríguez-Palma EJ, Huerta de la Cruz S, Islas-Espinoza AM, Castañeda-Corral G, Granados-Soto V, Khanna R. Nociplastic pain mechanisms and toll-like receptors as promising targets for its management. Pain 2024:00006396-990000000-00571. [PMID: 38595206 DOI: 10.1097/j.pain.0000000000003238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 02/29/2024] [Indexed: 04/11/2024]
Abstract
ABSTRACT Nociplastic pain, characterized by abnormal pain processing without an identifiable organic cause, affects a significant portion of the global population. Unfortunately, current pharmacological treatments for this condition often prove ineffective, prompting the need to explore new potential targets for inducing analgesic effects in patients with nociplastic pain. In this context, toll-like receptors (TLRs), known for their role in the immune response to infections, represent promising opportunities for pharmacological intervention because they play a relevant role in both the development and maintenance of pain. Although TLRs have been extensively studied in neuropathic and inflammatory pain, their specific contributions to nociplastic pain remain less clear, demanding further investigation. This review consolidates current evidence on the connection between TLRs and nociplastic pain, with a specific focus on prevalent conditions like fibromyalgia, stress-induced pain, sleep deprivation-related pain, and irritable bowel syndrome. In addition, we explore the association between nociplastic pain and psychiatric comorbidities, proposing that modulating TLRs can potentially alleviate both pain syndromes and related psychiatric disorders. Finally, we discuss the potential sex differences in TLR signaling, considering the higher prevalence of nociplastic pain among women. Altogether, this review aims to shed light on nociplastic pain, its underlying mechanisms, and its intriguing relationship with TLR signaling pathways, ultimately framing the potential therapeutic role of TLRs in addressing this challenging condition.
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Affiliation(s)
- Erick J Rodríguez-Palma
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL, United States
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | | | - Ana M Islas-Espinoza
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | | | - Vinicio Granados-Soto
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Rajesh Khanna
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL, United States
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6
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Michot B, Casey SM, Lee CS, Erdogan O, Basu H, Chiu I, Gibbs JL. Lipopolysaccharide-Induced TRPA1 Upregulation in Trigeminal Neurons is Dependent on TLR4 and Vesicular Exocytosis. J Neurosci 2023; 43:6731-6744. [PMID: 37643860 PMCID: PMC10552941 DOI: 10.1523/jneurosci.0162-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 07/28/2023] [Accepted: 07/31/2023] [Indexed: 08/31/2023] Open
Abstract
Pain from bacterial infection was believed to be the consequence of inflammation induced by bacterial products. However recent studies have shown that bacterial products can directly activate sensory neurons and induce pain. The mechanisms by which bacteria induce pain are poorly understood, but toll-like receptor (TLR)4 and transient receptor potential A1 (TRPA1) receptors are likely important integrators of pain signaling induced by bacteria. Using male and female mice we show that sensory neuron activation by bacterial lipopolysaccharides (LPS) is mediated by both TRPA1 and TLR4 and involves the mobilization of extracellular and intracellular calcium. We also show that LPS induces neuronal sensitization in a process dependent on TLR4 receptors. Moreover, we show that TLR4 and TRPA1 are both involved in sensory neurons response to LPS stimulation. Activation of TLR4 in a subset of sensory neurons induces TRPA1 upregulation at the cell membrane through vesicular exocytosis, contributing to the initiation of neuronal sensitization and pain. Collectively these data highlight the importance of sensory neurons to pathogen detection, and their activation by bacterial products like LPS as potentially important to early immune and nociceptive responses.SIGNIFICANCE STATEMENT Bacterial infections are often painful and the recent discovery that bacteria can directly stimulate sensory neurons leading to pain sensation and modulation of immune system have highlighted the importance of nervous system in the response to bacterial infection. Here, we showed that lipopolysaccharide, a major bacterial by-product, requires both toll-like receptor (TLR)4 and transient receptor potential A1 (TRPA1) receptors for neuronal activation and acute spontaneous pain, but only TLR4 mediates sensory neurons sensitization. Moreover, we showed for the first time that TLR4 sensitize sensory neurons through a rapid upregulation of TRPA1 via vesicular exocytosis. Our data highlight the importance of sensory neurons to pathogen detection and suggests that TLR4 would be a potential therapeutic target to modulate early stage of bacteria-induced pain and immune response.
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Affiliation(s)
- Benoit Michot
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts 02115
- Department of Endodontics, New York University College of Dentistry, New York, New York 10010
| | - Sharon M Casey
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts 02115
- Department of Endodontics, New York University College of Dentistry, New York, New York 10010
| | - Caroline S Lee
- Department of Endodontics, New York University College of Dentistry, New York, New York 10010
| | - Ozge Erdogan
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts 02115
| | - Himanish Basu
- Department of Immunology, Harvard Medical School, Boston, Massachusetts 02215
| | - Isaac Chiu
- Department of Immunology, Harvard Medical School, Boston, Massachusetts 02215
| | - Jennifer L Gibbs
- Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, Massachusetts 02115
- Department of Endodontics, New York University College of Dentistry, New York, New York 10010
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7
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Piñero G, Vence M, Aranda ML, Cercato MC, Soto PA, Usach V, Setton-Avruj PC. All the PNS is a Stage: Transplanted Bone Marrow Cells Play an Immunomodulatory Role in Peripheral Nerve Regeneration. ASN Neuro 2023; 15:17590914231167281. [PMID: 37654230 PMCID: PMC10475269 DOI: 10.1177/17590914231167281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 02/28/2023] [Accepted: 03/16/2023] [Indexed: 09/02/2023] Open
Abstract
SUMMARY STATEMENT Bone marrow cell transplant has proven to be an effective therapeutic approach to treat peripheral nervous system injuries as it not only promoted regeneration and remyelination of the injured nerve but also had a potent effect on neuropathic pain.
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Affiliation(s)
- Gonzalo Piñero
- Departamento de Química Biológica, Cátedra de Química Biológica Patalógica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
- Universidad de Buenos Aires-CONICET, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Ciudad Autónoma de Buenos Aires, Argentina
- Department of Pathology, Mount Sinai Hospital, New York, NY, USA
| | - Marianela Vence
- Universidad de Buenos Aires-CONICET, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Ciudad Autónoma de Buenos Aires, Argentina
| | - Marcos L. Aranda
- Universidad de Buenos Aires-CONICET, Centro de Estudios Farmacológicos y Botánicos (CEFYBO), Ciudad Autónoma de Buenos Aires, Argentina
- Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL, USA
| | - Magalí C. Cercato
- Universidad de Buenos Aires-CONICET, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Ciudad Autónoma de Buenos Aires, Argentina
| | - Paula A. Soto
- Departamento de Química Biológica, Cátedra de Química Biológica Patalógica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
- Universidad de Buenos Aires-CONICET, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Ciudad Autónoma de Buenos Aires, Argentina
| | - Vanina Usach
- Departamento de Química Biológica, Cátedra de Química Biológica Patalógica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
- Universidad de Buenos Aires-CONICET, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Ciudad Autónoma de Buenos Aires, Argentina
| | - Patricia C. Setton-Avruj
- Departamento de Química Biológica, Cátedra de Química Biológica Patalógica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
- Universidad de Buenos Aires-CONICET, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Ciudad Autónoma de Buenos Aires, Argentina
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Liu X, Yang W, Zhu C, Sun S, Wu S, Wang L, Wang Y, Ge Z. Toll-like receptors and their role in neuropathic pain and migraine. Mol Brain 2022; 15:73. [PMID: 35987639 PMCID: PMC9392297 DOI: 10.1186/s13041-022-00960-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 08/11/2022] [Indexed: 11/10/2022] Open
Abstract
Migraine is a complex neurological disease of unknown etiology involving both genetic and environmental factors. It has previously been reported that persistent pain may be mediated by the immune and inflammatory systems. Toll-like receptors (TLRs) play a significant role in immune and inflammatory responses and are expressed by microglia and astrocytes. One of the fundamental mechanisms of the innate immune system in coordinating inflammatory signal transduction is through TLRs, which protect the host organism by initiating inflammatory signaling cascades in response to tissue damage or stress. TLRs reside at the neuroimmune interface, and accumulating evidence has suggested that the inflammatory consequences of TLR activation on glia (mainly microglia and astrocytes), sensory neurons, and other cell types can influence nociceptive processing and lead to pain. Several studies have shown that TLRs may play a key role in neuropathic pain and migraine etiology by activating the microglia. The pathogenesis of migraine may involve a TLR-mediated crosstalk between neurons and immune cells. Innate responses in the central nervous system (CNS) occur during neuroinflammatory phenomena, including migraine. Antigens found in the environment play a crucial role in the inflammatory response, causing a broad range of diseases, including migraines. These can be recognized by several innate immune cells, including macrophages, microglia, and dendritic cells, and can be activated through TLR signaling. Given the prevalence of migraine and the insufficient efficacy and safety of current treatment options, a deeper understanding of TLRs is expected to provide novel therapies for managing chronic migraine. This review aimed to justify the view that TLRs may be involved in migraine.
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Lysophosphatidylcholine: Potential Target for the Treatment of Chronic Pain. Int J Mol Sci 2022; 23:ijms23158274. [PMID: 35955410 PMCID: PMC9368269 DOI: 10.3390/ijms23158274] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/22/2022] [Accepted: 07/23/2022] [Indexed: 12/26/2022] Open
Abstract
The bioactive lipid lysophosphatidylcholine (LPC), a major phospholipid component of oxidized low-density lipoprotein (Ox-LDL), originates from the cleavage of phosphatidylcholine by phospholipase A2 (PLA2) and is catabolized to other substances by different enzymatic pathways. LPC exerts pleiotropic effects mediated by its receptors, G protein-coupled signaling receptors, Toll-like receptors, and ion channels to activate several second messengers. Lysophosphatidylcholine (LPC) is increasingly considered a key marker/factor positively in pathological states, especially inflammation and atherosclerosis development. Current studies have indicated that the injury of nervous tissues promotes oxidative stress and lipid peroxidation, as well as excessive accumulation of LPC, enhancing the membrane hyperexcitability to induce chronic pain, which may be recognized as one of the hallmarks of chronic pain. However, findings from lipidomic studies of LPC have been lacking in the context of chronic pain. In this review, we focus in some detail on LPC sources, biochemical pathways, and the signal-transduction system. Moreover, we outline the detection methods of LPC for accurate analysis of each individual LPC species and reveal the pathophysiological implication of LPC in chronic pain, which makes it an interesting target for biomarkers and the development of medicine regarding chronic pain.
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10
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Li X, Tao YX. Intrathecal administration of the fat-mass and obesity-associated protein inhibitor mitigates neuropathic pain in female rats. TRANSLATIONAL PERIOPERATIVE AND PAIN MEDICINE 2022; 9:478-487. [PMID: 36545239 PMCID: PMC9764434 DOI: 10.31480/2330-4871/163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Several intracellular signals are involved in the sexual dimorphism of chronic pain. Our previous studies demonstrated that the fat-mass and obesity-associated protein (FTO), a demethylase of RNA N6-methyladenosine, in the injured dorsal root ganglion (DRG) contributed to the development and maintenance of nerve injury-induced nociceptive hypersensitivity in male rats and male mice. However, whether these effects of DRG FTO are in a sex-dependent manner is still unknown. The present study sought to investigate the effect of intrathecal administration of a specific FTO inhibitor, meclofenamic acid (MA), on chronic constriction injury (CCI)-induced nociceptive hypersensitivity in female rats. Intrathecal injection of MA attenuated the CCI-induced mechanical allodynia, heat hyperalgesia, and cold hyperalgesia in both the induction and maintenance periods, without changing acute/basal pain and locomotor function, in female rats. Intrathecal MA also blocked the CCI-induced hyperactivations of neurons and astrocytes in the ipsilateral L4 and L5 dorsal horns of female rats. Mechanistically, intrathecal MA prevented the CCI-induced increase in the histone methyltransferase G9a expression and reversed the G9a-controlled downregulation of mu-opioid receptor and Kv1.2 proteins in the ipsilateral L4 and L5 DRGs of female rats. These findings indicate that the effects of the FTO inhibitor on nerve injury-induced nociceptive hypersensitivity in female rats are similar to those in male rats reported previously. Our data also further confirm the role of DRG FTO in neuropathic pain and suggest potential clinical application of the FTO inhibitors for the prevention and treatment of this disorder in both men and women.
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Affiliation(s)
- Xiang Li
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Yuan-Xiang Tao
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA,Department of Physiology, Pharmacology & Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ07103, USA,Departments of Cell Biology & Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
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11
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Chernov AV, Shubayev VI. Sexual Dimorphism of Early Transcriptional Reprogramming in Dorsal Root Ganglia After Peripheral Nerve Injury. Front Mol Neurosci 2021; 14:779024. [PMID: 34966260 PMCID: PMC8710713 DOI: 10.3389/fnmol.2021.779024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/19/2021] [Indexed: 01/18/2023] Open
Abstract
Peripheral nerve injury induces genome-wide transcriptional reprogramming of first-order neurons and auxiliary cells of dorsal root ganglia (DRG). Accumulating experimental evidence suggests that onset and mechanistic principles of post-nerve injury processes are sexually dimorphic. We examined largely understudied aspects of early transcriptional events in DRG within 24 h after sciatic nerve axotomy in mice of both sexes. Using high-depth RNA sequencing (>50 million reads/sample) to pinpoint sexually dimorphic changes related to regeneration, immune response, bioenergy, and sensory functions, we identified a higher number of transcriptional changes in male relative to female DRG. In males, the decline in ion channel transcripts was accompanied by the induction of innate immune cascades via TLR, chemokine, and Csf1-receptor axis and robust regenerative programs driven by Sox, Twist1/2, and Pax5/9 transcription factors. Females demonstrated nerve injury-specific transcriptional co-activation of the actinin 2 network. The predicted upstream regulators and interactive networks highlighted the role of novel epigenetic factors and genetic linkage to sex chromosomes as hallmarks of gene regulation post-axotomy. We implicated epigenetic X chromosome inactivation in the regulation of immune response activity uniquely in females. Sexually dimorphic regulation of MMP/ADAMTS metalloproteinases and their intrinsic X-linked regulator Timp1 contributes to extracellular matrix remodeling integrated with pro-regenerative and immune functions. Lexis1 non-coding RNA involved in LXR-mediated lipid metabolism was identified as a novel nerve injury marker. Together, our data identified unique early response triggers of sex-specific peripheral nerve injury regulation to gain mechanistic insights into the origin of female- and male-prevalent sensory neuropathies.
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Affiliation(s)
- Andrei V Chernov
- Department of Anesthesiology, University of California, San Diego, San Diego, CA, United States.,VA San Diego Healthcare System, San Diego, CA, United States
| | - Veronica I Shubayev
- Department of Anesthesiology, University of California, San Diego, San Diego, CA, United States.,VA San Diego Healthcare System, San Diego, CA, United States
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Sensory Neuron TLR4 mediates the development of nerve-injury induced mechanical hypersensitivity in female mice. Brain Behav Immun 2021; 97:42-60. [PMID: 34174335 PMCID: PMC8453057 DOI: 10.1016/j.bbi.2021.06.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 06/08/2021] [Accepted: 06/18/2021] [Indexed: 02/07/2023] Open
Abstract
Recent studies have brought to light the necessity to discern sex-specific differences in various pain states and different cell-types that mediate these differences. These studies have uncovered the role of neuroimmune interactions to mediate pain states in a sex-specific fashion. While investigating immune function in pain development, we discovered that females utilize immune components of sensory neurons to mediate neuropathic pain development. We utilized two novel transgenic mouse models that eitherrestore expression of toll-like receptor (TLR) 4 inNav1.8 nociceptors on a TLR4-null background (TLR4LoxTB) or remove TLR4 specifically from Nav1.8 nociceptors (TLR4fl/fl). After spared nerve injury (SNI), a model of neuropathic injury, we observed a robust female-specific onset of mechanical hypersensitivity in our transgenic animals. Female Nav1.8-TLR4fl/fl knockout animals were less mechanically sensitive than cre-negative TLR4fl/fl littermates. Conversely, female Nav1.8-TLR4LoxTB reactivated animals were as mechanically sensitive as their wild-type counterparts. These sex and cell-specific effects were not recapitulated in male animals of either strain. Additionally, we find the danger associated molecular pattern, high mobility group box-1 (HGMB1), a potent TLR4 agonist, localization and ATF3 expression in females is dependent on TLR4 expression in dorsal root ganglia (DRG) populations following SNI. These experiments provide novel evidence toward sensory neuron specific modulation of pain in a sex-dependent manner.
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Application of Bioinformatics Methods to Identify Key Genes and Functions in Chronic Pelvic Pain. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2021; 2021:7257405. [PMID: 34381521 PMCID: PMC8352682 DOI: 10.1155/2021/7257405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 07/19/2021] [Indexed: 11/17/2022]
Abstract
Neuropathologic pain (NPP) occurs in most patients with chronic pelvic pain (CPP), and the unique physiological characteristics of visceral sensory neurons make the current analgesic effect of CPP patients not optimistic. Therefore, this study explored the possible biological characteristics of key genes in CPP through the bioinformatics method. CPP-related dataset GSE131619 was downloaded from Gene Expression Omnibus to investigate the differentially expressed genes (DEGs) between lumbar dorsal root ganglia (DRG) and sacral DRG, and the functional enrichment analysis was performed. A protein-protein interaction (PPI) network was constructed to search subnet modules of specific biological processes, and then, the genes in the subnet were enriched by single gene set analysis. A CPP mouse model was established, and the expression of key genes were identified by qPCR. The results showed that 127 upregulated DEGs and 103 downregulated DEGs are identified. Functional enrichment analysis showed that most of the genes involved in signal transduction were involved in the pathway of receptor interaction. A subnet module related to neural signal regulation was identified in PPI, including CHRNB4, CHRNA3, and CHRNB2. All three genes were associated with neurological or inflammatory activity and are downregulated in the sacral spinal cord of CPP mice. This study provided three key candidate genes for CPP: CHRNB4, CHRNA3, and CHRNB2, which may be involved in the occurrence and development of CPP, and provided a powerful molecular target for the clinical diagnosis and treatment of CPP.
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Gregus AM, Levine IS, Eddinger KA, Yaksh TL, Buczynski MW. Sex differences in neuroimmune and glial mechanisms of pain. Pain 2021; 162:2186-2200. [PMID: 34256379 PMCID: PMC8277970 DOI: 10.1097/j.pain.0000000000002215] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 12/03/2020] [Indexed: 02/07/2023]
Abstract
ABSTRACT Pain is the primary motivation for seeking medical care. Although pain may subside as inflammation resolves or an injury heals, it is increasingly evident that persistency of the pain state can occur with significant regularity. Chronic pain requires aggressive management to minimize its physiological consequences and diminish its impact on quality of life. Although opioids commonly are prescribed for intractable pain, concerns regarding reduced efficacy, as well as risks of tolerance and dependence, misuse, diversion, and overdose mortality rates limit their utility. Advances in development of nonopioid interventions hinge on our appreciation of underlying mechanisms of pain hypersensitivity. For instance, the contributory role of immunity and the associated presence of autoimmune syndromes has become of particular interest. Males and females exhibit fundamental differences in innate and adaptive immune responses, some of which are present throughout life, whereas others manifest with reproductive maturation. In general, the incidence of chronic pain conditions, particularly those with likely autoimmune covariates, is significantly higher in women. Accordingly, evidence is now accruing in support of neuroimmune interactions driving sex differences in the development and maintenance of pain hypersensitivity and chronicity. This review highlights known sexual dimorphisms of neuroimmune signaling in pain states modeled in rodents, which may yield potential high-value sex-specific targets to inform future analgesic drug discovery efforts.
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Affiliation(s)
- Ann M Gregus
- School of Neuroscience, Virginia Polytechnic and State University, Blacksburg, VA, United States
| | - Ian S Levine
- School of Neuroscience, Virginia Polytechnic and State University, Blacksburg, VA, United States
| | | | - Tony L Yaksh
- Departments of Anesthesiology and
- Pharmacology, University of California San Diego, La Jolla, CA, United States
| | - Matthew W Buczynski
- School of Neuroscience, Virginia Polytechnic and State University, Blacksburg, VA, United States
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Jiang ZJ, Li QY, Zhang YY, Zeng MX, Hu H, Zhang FM, Bi LB, Gu JH, Liu XJ. Deletion of MyD88 adaptor in nociceptor alleviates low-dose formalin-induced acute pain and persistent pain in mice. Neuroreport 2021; 32:378-385. [PMID: 33661805 DOI: 10.1097/wnr.0000000000001608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The myeloid differentiation factor 88 (MyD88) adaptor mediates signaling by Toll-like receptors and some interleukins (ILs) in neural and non-neuronal cells. Recently, MyD88 protein was found to express in primary sensory neurons and be involved in the maintenance of persistent pain induced by complete Freund's adjuvant, chronic constriction injury and chemotherapy treatment in rodents. However, whether MyD88 in nociceptive neurons contributes to persistent pain induced by intraplantar injection of formalin remains elusive. Here, using conditional knockout (CKO) mice, we found that selective deletion of Myd88 in Nav1.8-expressing primary nociceptive neurons led to reduced pain response in the recovery phase of 1% formalin-induced mechanical pain and impaired the persistent thermal pain. Moreover, CKO mice exhibited reduced phase II pain response in 1%, but not 5%, formalin-induced acute inflammatory pain. Finally, nociceptor MyD88 deletion resulted in less neuronal c-Fos activation in spinal dorsal horns following 1% formalin stimulation. These data suggest that MyD88 in nociceptive neurons is not only involved in persistent mechanical pain but also promotes the transition from acute inflammatory pain to persistent thermal hyperalgesia induced by low-dose formalin stimulation.
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Affiliation(s)
- Zuo-Jie Jiang
- Pain and Related Disease Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province
| | - Qing-Yi Li
- Pain and Related Disease Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province
| | - Ying-Ying Zhang
- Department of Anesthesiology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing
| | - Mei-Xing Zeng
- Pain and Related Disease Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province
| | - Han Hu
- Institute of Apicultural Research/Key Laboratory of Pollinating Insect Biology, Ministry of Agriculture, Chinese Academy of Agricultural Sciences, No. 1 Beigou Xiangshan, Beijing, China
| | - Feng-Ming Zhang
- Pain and Related Disease Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province
| | - Ling-Bo Bi
- Pain and Related Disease Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province
| | - Jia-Hui Gu
- Pain and Related Disease Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province
| | - Xing-Jun Liu
- Pain and Related Disease Research Laboratory, Shantou University Medical College, Shantou, Guangdong Province
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Su W, Cui H, Wu D, Yu J, Ma L, Zhang X, Huang Y, Ma C. Suppression of TLR4-MyD88 signaling pathway attenuated chronic mechanical pain in a rat model of endometriosis. J Neuroinflammation 2021; 18:65. [PMID: 33673857 PMCID: PMC7934423 DOI: 10.1186/s12974-020-02066-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/21/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND As a classic innate immunity pathway, Toll-like receptor 4 (TLR4) signaling has been intensively investigated for its function of pathogen recognition. The receptor is located not only on immune cells but also on sensory neurons and spinal glia. Recent studies revealed the involvement of neuronal TLR4 in different types of pain. However, the specific role of TLR4 signaling in the pain symptom of endometriosis (EM) remains obscure. METHODS The rat endometriosis model was established by transplanting uterine horn tissue into gastrocnemius. Western blotting and/or immunofluorescent staining were applied to detect high mobility group box 1 (HMGB1), TLR4, myeloid differentiation factor-88 adaptor protein (MyD88), and nuclear factor kappa-B-p65 (NF-κB-p65) expression, as well as the activation of astrocyte and microglia. The antagonist of TLR4 (LPS-RS-Ultra, LRU) and MyD88 homodimerization inhibitory peptide (MIP) were intrathecally administrated to assess the behavioral effects of blocking TLR4 signaling on endometriosis-related pain. RESULTS Mechanical hyperalgesia was observed at the graft site, while HMGB1 was upregulated in the implanted uterine tissue, dorsal root ganglion (DRG), and spinal dorsal horn (SDH). Compared with sham group, upregulated TLR4, MyD88, and phosphorylated NF-κB-p65 were detected in the DRG and SDH in EM rats. The activation of astrocytes and microglia in the SDH was also confirmed in EM rats. Intrathecal application of LRU and MIP alleviated mechanical pain on the graft site of EM rats, with decreased phosphorylation of NF-κB-p65 in the DRG and reduced activation of glia in the SDH. CONCLUSIONS HMGB1-TLR4-MyD88 signaling pathway in the DRG and SDH may involve in endometriosis-related hyperpathia. Blockade of TLR4 and MyD88 might serve as a potential treatment for pain in endometriosis.
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Affiliation(s)
- Wenliang Su
- Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Huan Cui
- Department of Human Anatomy, Histology and Embryology, Institute of Basic Medical Sciences, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Danning Wu
- Department of Human Anatomy, Histology and Embryology, Institute of Basic Medical Sciences, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
| | - Jiawen Yu
- Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Lulu Ma
- Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xiuhua Zhang
- Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yuguang Huang
- Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
| | - Chao Ma
- Department of Human Anatomy, Histology and Embryology, Institute of Basic Medical Sciences, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China.
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Kwilasz AJ, Green Fulgham SM, Duran-Malle JC, Schrama AEW, Mitten EH, Todd LS, Patel HP, Larson TA, Clements MA, Harris KM, Litwiler ST, Harvey LO, Maier SF, Chavez RA, Rice KC, Van Dam AM, Watkins LR. Toll-like receptor 2 and 4 antagonism for the treatment of experimental autoimmune encephalomyelitis (EAE)-related pain. Brain Behav Immun 2021; 93:80-95. [PMID: 33358978 PMCID: PMC8475740 DOI: 10.1016/j.bbi.2020.12.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 12/07/2020] [Accepted: 12/16/2020] [Indexed: 12/26/2022] Open
Abstract
Neuropathic pain is a major symptom of multiple sclerosis (MS) with up to 92% of patients reporting bodily pain, and 85% reporting pain severe enough to cause functional disability. None of the available therapeutics target MS pain. Toll-like receptors 2 and 4 (TLR2/TLR4) have emerged as targets for treating a wide array of autoimmune disorders, including MS, as well as having demonstrated success at suppressing pain in diverse animal models. The current series of studies tested systemic TLR2/TLR4 antagonists in males and females in a low-dose Myelin oligodendrocyte glycoprotein (MOG) experimental autoimmune encephalomyelitis (EAE) model, with reduced motor dysfunction to allow unconfounded testing of allodynia through 50+ days post-MOG. The data demonstrated that blocking TLR2/TLR4 suppressed EAE-related pain, equally in males and females; upregulation of dorsal spinal cord proinflammatory gene expression for TLR2, TLR4, NLRP3, interleukin-1β, IkBα, TNF-α and interleukin-17; and upregulation of dorsal spinal cord expression of glial immunoreactivity markers. In support of these results, intrathecal interleukin-1 receptor antagonist reversed EAE-induced allodynia, both early and late after EAE induction. In contrast, blocking TLR2/TLR4 did not suppress EAE-induced motor disturbances induced by a higher MOG dose. These data suggest that blocking TLR2/TLR4 prevents the production of proinflammatory factors involved in low dose EAE pathology. Moreover, in this EAE model, TLR2/TLR4 antagonists were highly effective in reducing pain, whereas motor impairment, as seen in high dose MOG EAE, is not affected.
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Affiliation(s)
- Andrew J Kwilasz
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States.
| | - Suzanne M Green Fulgham
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Julissa Chante Duran-Malle
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Anouk E W Schrama
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Eric H Mitten
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Laurel S Todd
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Hardik P Patel
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Tracey A Larson
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Madison A Clements
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Kevin M Harris
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Scott T Litwiler
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Lewis O Harvey
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Steven F Maier
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | | | - Kenner C Rice
- Drug Design and Synthesis Section, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, United States
| | - Anne-Marie Van Dam
- Department of Anatomy and Neuroscience, Amsterdam UMC, Vrije Universiteit, Amsterdam, Netherlands
| | - Linda R Watkins
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States; The Center for Neuroscience, University of Colorado, Boulder, CO, United States
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18
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Chang C, Liu HK, Yeh CB, Yang ML, Liao WC, Liu CH, Tseng TJ. Cross-Talk of Toll-Like Receptor 5 and Mu-Opioid Receptor Attenuates Chronic Constriction Injury-Induced Mechanical Hyperalgesia through a Protein Kinase C Alpha-Dependent Signaling. Int J Mol Sci 2021; 22:1891. [PMID: 33673008 PMCID: PMC7918001 DOI: 10.3390/ijms22041891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/30/2021] [Accepted: 02/10/2021] [Indexed: 12/11/2022] Open
Abstract
Recently, Toll-like receptors (TLRs), a family of pattern recognition receptors, are reported as potential modulators for neuropathic pain; however, the desired mechanism is still unexplained. Here, we operated on the sciatic nerve to establish a pre-clinical rodent model of chronic constriction injury (CCI) in Sprague-Dawley rats, which were assigned into CCI and Decompression groups randomly. In Decompression group, the rats were performed with nerve decompression at post-operative week 4. Mechanical hyperalgesia and mechanical allodynia were obviously attenuated after a month. Toll-like receptor 5 (TLR5)-immunoreactive (ir) expression increased in dorsal horn, particularly in the inner part of lamina II. Additionally, substance P (SP) and isolectin B4 (IB4)-ir expressions, rather than calcitonin-gene-related peptide (CGRP)-ir expression, increased in their distinct laminae. Double immunofluorescence proved that increased TLR5-ir expression was co-expressed mainly with IB4-ir expression. Through an intrathecal administration with FLA-ST Ultrapure (a TLR5 agonist, purified flagellin from Salmonella Typhimurium, only the CCI-induced mechanical hyperalgesia was attenuated dose-dependently. Moreover, we confirmed that mu-opioid receptor (MOR) and phospho-protein kinase Cα (pPKCα)-ir expressions but not phospho-protein kinase A RII (pPKA RII)-ir expression, increased in lamina II, where they mostly co-expressed with IB4-ir expression. Go 6976, a potent protein kinase C inhibitor, effectively reversed the FLA-ST Ultrapure- or DAMGO-mediated attenuated trend towards mechanical hyperalgesia by an intrathecal administration in CCI rats. In summary, our current findings suggest that nerve decompression improves CCI-induced mechanical hyperalgesia that might be through the cross-talk of TLR5 and MOR in a PKCα-dependent manner, which opens a novel opportunity for the development of analgesic therapeutics in neuropathic pain.
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Affiliation(s)
- Ching Chang
- Department of Anatomy, School of Medicine, Chung Shan Medical University, 40201 Taichung, Taiwan; (C.C.); (H.-K.L.); (M.-L.Y.); (W.-C.L.); (C.-H.L.)
| | - Hung-Kai Liu
- Department of Anatomy, School of Medicine, Chung Shan Medical University, 40201 Taichung, Taiwan; (C.C.); (H.-K.L.); (M.-L.Y.); (W.-C.L.); (C.-H.L.)
| | - Chao-Bin Yeh
- Department of Emergency Medicine, Chung Shan Medical University Hospital, 40201 Taichung, Taiwan;
- Department of Emergency Medicine, School of Medicine, Chung Shan Medical University, 40201 Taichung, Taiwan
| | - Ming-Lin Yang
- Department of Anatomy, School of Medicine, Chung Shan Medical University, 40201 Taichung, Taiwan; (C.C.); (H.-K.L.); (M.-L.Y.); (W.-C.L.); (C.-H.L.)
- Department of Medical Education, Chung Shan Medical University Hospital, 40201 Taichung, Taiwan
| | - Wen-Chieh Liao
- Department of Anatomy, School of Medicine, Chung Shan Medical University, 40201 Taichung, Taiwan; (C.C.); (H.-K.L.); (M.-L.Y.); (W.-C.L.); (C.-H.L.)
- Department of Medical Education, Chung Shan Medical University Hospital, 40201 Taichung, Taiwan
| | - Chiung-Hui Liu
- Department of Anatomy, School of Medicine, Chung Shan Medical University, 40201 Taichung, Taiwan; (C.C.); (H.-K.L.); (M.-L.Y.); (W.-C.L.); (C.-H.L.)
- Department of Medical Education, Chung Shan Medical University Hospital, 40201 Taichung, Taiwan
| | - To-Jung Tseng
- Department of Anatomy, School of Medicine, Chung Shan Medical University, 40201 Taichung, Taiwan; (C.C.); (H.-K.L.); (M.-L.Y.); (W.-C.L.); (C.-H.L.)
- Department of Medical Education, Chung Shan Medical University Hospital, 40201 Taichung, Taiwan
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Midavaine É, Côté J, Marchand S, Sarret P. Glial and neuroimmune cell choreography in sexually dimorphic pain signaling. Neurosci Biobehav Rev 2021; 125:168-192. [PMID: 33582232 DOI: 10.1016/j.neubiorev.2021.01.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/03/2020] [Accepted: 01/25/2021] [Indexed: 12/17/2022]
Abstract
Chronic pain is a major global health issue that affects all populations regardless of sex, age, ethnicity/race, or country of origin, leading to persistent physical and emotional distress and to the loss of patients' autonomy and quality of life. Despite tremendous efforts in the elucidation of the mechanisms contributing to the pathogenesis of chronic pain, the identification of new potential pain targets, and the development of novel analgesics, the pharmacological treatment options available for pain management remain limited, and most novel pain medications have failed to achieve advanced clinical development, leaving many patients with unbearable and undermanaged pain. Sex-specific susceptibility to chronic pain conditions as well as sex differences in pain sensitivity, pain tolerance and analgesic efficacy are increasingly recognized in the literature and have thus prompted scientists to seek mechanistic explanations. Hence, recent findings have highlighted that the signaling mechanisms underlying pain hypersensitivity are sexually dimorphic, which sheds light on the importance of conducting preclinical and clinical pain research on both sexes and of developing sex-specific pain medications. This review thus focuses on the clinical and preclinical evidence supporting the existence of sex differences in pain neurobiology. Attention is drawn to the sexually dimorphic role of glial and immune cells, which are both recognized as key players in neuroglial maladaptive plasticity at the origin of the transition from acute pain to chronic pathological pain. Growing evidence notably attributes to microglial cells a pivotal role in the sexually dimorphic pain phenotype and in the sexually dimorphic analgesic efficacy of opioids. This review also summarizes the recent advances in understanding the pathobiology underpinning the development of pain hypersensitivity in both males and females in different types of pain conditions, with particular emphasis on the mechanistic signaling pathways driving sexually dimorphic pain responses.
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Affiliation(s)
- Élora Midavaine
- Department of Pharmacology-Physiology, Institut de pharmacologie de Sherbrooke, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada; Centre de recherche du Centre hospitalier universitaire de Sherbrooke, CIUSSS de l'Estrie - CHUS, Sherbrooke, Québec, Canada.
| | - Jérôme Côté
- Department of Pharmacology-Physiology, Institut de pharmacologie de Sherbrooke, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada; Centre de recherche du Centre hospitalier universitaire de Sherbrooke, CIUSSS de l'Estrie - CHUS, Sherbrooke, Québec, Canada
| | - Serge Marchand
- Department of Pharmacology-Physiology, Institut de pharmacologie de Sherbrooke, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada; Centre de recherche du Centre hospitalier universitaire de Sherbrooke, CIUSSS de l'Estrie - CHUS, Sherbrooke, Québec, Canada
| | - Philippe Sarret
- Department of Pharmacology-Physiology, Institut de pharmacologie de Sherbrooke, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada; Centre de recherche du Centre hospitalier universitaire de Sherbrooke, CIUSSS de l'Estrie - CHUS, Sherbrooke, Québec, Canada.
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20
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Wang Y, Dai G, Xu Y, Jiang L, Fu Z, Xia J, Tian G, Du W. Integrated traditional Chinese medicine alleviates sciatica while regulating gene expression in peripheral blood. J Orthop Surg Res 2021; 16:130. [PMID: 33573686 PMCID: PMC7877113 DOI: 10.1186/s13018-021-02280-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 02/03/2021] [Indexed: 12/16/2022] Open
Abstract
Background Although integrated traditional Chinese medicine (TCM) has long been indicated to be effective in the treatment of sciatica and is widely used in the management of this condition, the mechanism by which integrated TCM alleviates sciatica has not yet been fully defined, and the effect of integrated TCM on gene expression in the peripheral blood of patients with sciatica is still unknown. We performed this study to investigate the effect of integrated TCM on peripheral blood gene expression in patients with sciatica and to explore new clues for studying the mechanism of integrated TCM in alleviating sciatica. Methods We used a microarray to identify differentially expressed genes (DEGs) in the peripheral blood of patients with sciatica and healthy controls (DEGs-baseline), bioinformatic analysis to reveal the characteristics of DEGs-baseline, and the key genes that contribute to the gene dysregulation. A microarray was also used to identify DEGs in the peripheral blood of patients with sciatica after integrated TCM treatment compared with those at baseline, and the expression levels of DEGs were validated by qRT-PCR. Results We identified 153 DEGs-baseline, which included 131 upregulated genes and 22 downregulated genes. Bioinformatic analysis revealed that most of the DEGs-baseline were related to immunity and the inflammatory response and that TLR4, MMP9, MPO, CAMP, RETN, TLR5, and IL1RN were key genes involved in the dysregulation of genes in the peripheral blood of patients with sciatica. The expression levels of TLR5, IL1RN, SLC8A1, RBM20, GPER1, IL27, SOCS1, and GRTP1-AS1 were decreased in the peripheral blood of patients after integrated TCM treatment compared with that at baseline, which was accompanied by relief of pain. Conclusion Integrated TCM treatment relieved pain while regulating the gene expression of TLR5, IL1RN, SLC8A1, RBM20, GPER1, IL27, SOCS1, and GRTP1-AS1 in the peripheral blood of patients with sciatica. Our study provides new clues for studying the mechanism of TCM in treating sciatica. Supplementary Information The online version contains supplementary material available at 10.1186/s13018-021-02280-1.
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Affiliation(s)
- Yi Wang
- Cervicodynia/Omalgia/Lumbago/Sciatica Department 2, Sichuan Provincial Orthopedics Hospital, No. 132 West First Section First Ring Road, Wuhou District, Chengdu, Sichuan Province, China.
| | - Guogang Dai
- Cervicodynia/Omalgia/Lumbago/Sciatica Department 2, Sichuan Provincial Orthopedics Hospital, No. 132 West First Section First Ring Road, Wuhou District, Chengdu, Sichuan Province, China
| | - Yan Xu
- Experiment Teaching Center for Preclinical Medicine, Chengdu Medical College, No. 783, Xindu Avenue, Xindu District, Chengdu, Sichuan Province, China
| | - Ling Jiang
- College Hospital, Sichuan Agricultural University, Chengdu Campus, No. 211 Huiming Road, Wenjiang District, Chengdu, Sichuan Province, China
| | - Zhibin Fu
- Department of Lower Extremities, Sport Hospital Affiliated to Chengdu Sport Institute, No. 2, Tiyuan Road, Wuhou District, Chengdu, Sichuan Province, China
| | - Jiao Xia
- Cervicodynia/Omalgia/Lumbago/Sciatica Department 2, Sichuan Provincial Orthopedics Hospital, No. 132 West First Section First Ring Road, Wuhou District, Chengdu, Sichuan Province, China
| | - Guogang Tian
- Cervicodynia/Omalgia/Lumbago/Sciatica Department 2, Sichuan Provincial Orthopedics Hospital, No. 132 West First Section First Ring Road, Wuhou District, Chengdu, Sichuan Province, China
| | - Wanli Du
- Cervicodynia/Omalgia/Lumbago/Sciatica Department 2, Sichuan Provincial Orthopedics Hospital, No. 132 West First Section First Ring Road, Wuhou District, Chengdu, Sichuan Province, China
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21
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de Weerd NA, Vivian JP, Lim SS, Huang SUS, Hertzog PJ. Structural integrity with functional plasticity: what type I IFN receptor polymorphisms reveal. J Leukoc Biol 2021; 108:909-924. [PMID: 33448473 DOI: 10.1002/jlb.2mr0420-152r] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 03/21/2020] [Accepted: 03/26/2020] [Indexed: 12/13/2022] Open
Abstract
The type I IFNs activate an array of signaling pathways, which are initiated after IFNs bind their cognate receptors, IFNα/β receptor (IFNAR)1 and IFNAR2. These signals contribute to many aspects of human health including defense against pathogens, cancer immunosurveillance, and regulation of inflammation. How these cytokines interact with their receptors influences the quality of these signals. As such, the integrity of receptor structure is pivotal to maintaining human health and the response to immune stimuli. This review brings together genome wide association studies and clinical reports describing the association of nonsynonymous IFNAR1 and IFNAR2 polymorphisms with clinical disease, including altered susceptibility to viral and bacterial pathogens, autoimmune diseases, cancer, and adverse reactions to live-attenuated vaccines. We describe the amino acid substitutions or truncations induced by these polymorphisms and, using the knowledge of IFNAR conformational changes, IFNAR-IFN interfaces and overall structure-function relationship of the signaling complexes, we hypothesize the effect of these polymorphisms on receptor structure. That these predicted changes to IFNAR structure are associated with clinical manifestations of human disease, highlights the importance of IFNAR structural integrity to maintaining functional quality of these receptor-mediated responses. Type I IFNs are pivotal to innate immune responses and ultimately, to human health. Understanding the consequences of altered structure on the actions of these clinically significant cell receptors provides important information on the roles of IFNARs in health and disease.
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Affiliation(s)
- Nicole A de Weerd
- Centre for Innate Immunity and Infectious Diseases, Department of Molecular and Translational Science, Hudson Institute of Medical Research and Monash University, Clayton, Victoria, Australia
| | - Julian P Vivian
- Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute and Australian Research Council Centre for Excellence for Advanced Molecular Imaging, Monash University, Clayton, Victoria, Australia
| | - San S Lim
- Centre for Innate Immunity and Infectious Diseases, Department of Molecular and Translational Science, Hudson Institute of Medical Research and Monash University, Clayton, Victoria, Australia
| | - Stephanie U-Shane Huang
- Centre for Innate Immunity and Infectious Diseases, Department of Molecular and Translational Science, Hudson Institute of Medical Research and Monash University, Clayton, Victoria, Australia
| | - Paul J Hertzog
- Centre for Innate Immunity and Infectious Diseases, Department of Molecular and Translational Science, Hudson Institute of Medical Research and Monash University, Clayton, Victoria, Australia
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22
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Wang Y, Dai G, Jiang L, Liao S, Xia J. Microarray analysis reveals an inflammatory transcriptomic signature in peripheral blood for sciatica. BMC Neurol 2021; 21:50. [PMID: 33535986 PMCID: PMC7856817 DOI: 10.1186/s12883-021-02078-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 01/26/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Although the pathology of sciatica has been studied extensively, the transcriptional changes in the peripheral blood caused by sciatica have not been characterized. This study aimed to characterize the peripheral blood transcriptomic signature for sciatica. METHODS We used a microarray to identify differentially expressed genes in the peripheral blood of patients with sciatica compared with that of healthy controls, performed a functional analysis to reveal the peripheral blood transcriptomic signature for sciatica, and conducted a network analysis to identify key genes that contribute to the observed transcriptional changes. The expression levels of these key genes were assessed by qRT-PCR. RESULTS We found that 153 genes were differentially expressed in the peripheral blood of patients with sciatica compared with that of healthy controls, and 131 and 22 of these were upregulated and downregulated, respectively. A functional analysis revealed that these differentially expressed genes (DEGs) were strongly enriched for the inflammatory response or immunity. The network analysis revealed that a group of genes, most of which are related to the inflammatory response, played a key role in the dysregulation of these DEGs. These key genes are Toll-like receptor 4, matrix metallopeptidase 9, myeloperoxidase, cathelicidin antimicrobial peptide, resistin and Toll-like receptor 5, and a qRT-PCR analysis validated the higher transcript levels of these key genes in the peripheral blood of patients with sciatica than in that of healthy controls. CONCLUSION We revealed inflammatory characteristics that serve as a peripheral blood transcriptomic signature for sciatica and identified genes that are essential for mRNA dysregulation in the peripheral blood of patients with sciatica.
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Affiliation(s)
- Yi Wang
- Cervicodynia/Omalgia/Lumbago/Sciatica Department 2, Sichuan Provincial Orthopedics Hospital, No. 132 West First Section First Ring Road,Wuhou District, Chengdu, 610041, Sichuan Province, China.
| | - Guogang Dai
- Cervicodynia/Omalgia/Lumbago/Sciatica Department 2, Sichuan Provincial Orthopedics Hospital, No. 132 West First Section First Ring Road,Wuhou District, Chengdu, 610041, Sichuan Province, China
| | - Ling Jiang
- College Hospital, Sichuan Agricultural University-Chengdu Campus, NO. 211 Huimin Road, Wenjiang District, Chengdu, 611130, Sichuan Province, China
| | - Shichuan Liao
- Cervicodynia/Omalgia/Lumbago/Sciatica Department 2, Sichuan Provincial Orthopedics Hospital, No. 132 West First Section First Ring Road,Wuhou District, Chengdu, 610041, Sichuan Province, China
| | - Jiao Xia
- Cervicodynia/Omalgia/Lumbago/Sciatica Department 2, Sichuan Provincial Orthopedics Hospital, No. 132 West First Section First Ring Road,Wuhou District, Chengdu, 610041, Sichuan Province, China
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23
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Wang W, Huang F, Jiang W, Wang W, Xiang J. Brilliant blue G attenuates neuro-inflammation via regulating MAPKs and NF-κB signaling pathways in lipopolysaccharide-induced BV2 microglia cells. Exp Ther Med 2020; 20:116. [PMID: 33005242 PMCID: PMC7523273 DOI: 10.3892/etm.2020.9244] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 11/21/2019] [Indexed: 02/07/2023] Open
Abstract
Previous studies have demonstrated that the P2X purinoceptor 7 (P2X7) receptor (P2X7R) serves a critical role in regulating the inflammatory response of various diseases in the central nervous system. The anti-inflammatory effect of brilliant blue G (BBG), a specific antagonist of the P2X7R, remains unclear in lipopolysaccharide (LPS)-induced BV-2 cells. The present study suggested that BBG attenuated the neuroinflammatory response; the protein levels of inducible oxide synthase and cyclooxygenase-2, and the mRNA and secretion levels of pro-inflammatory cytokines including interleukin (IL)-16, IL-1β and tumor necrosis factor-α (TNF-α), were all decreased in LPS-induced BV2 cells. BBG inhibited the activation of MAPKs by inhibiting the phosphorylation of p38 mitogen-activated protein kinase, c-Jun N-terminal kinase and extracellular signal-regulated kinase. Notably, transcription factor p65 nuclear translocation was also inhibited, thereby leading to the inactivation of NF-κB. The inhibitory effects of BBG on MAPKs and NF-κB were additionally enhanced through the application of MAPK and NF-κB inhibitors. Taken together, the results demonstrated that BBG contributed to the suppression of the inflammatory effects in LPS-induced BV2 cells via the inhibition of NF-κB and MAPKs signaling pathways.
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Affiliation(s)
- Wei Wang
- Department of Rehabilitation, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221002, P.R. China.,School of Medical Technology, Xuzhou Medical University, Xuzhou, Jiangsu 221004, P.R. China
| | - Feiran Huang
- Department of Neurology, The Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212001, P.R. China
| | - Weifeng Jiang
- Department of Neurology, The Second People's Hospital of Quzhou, Quzhou, Zhejiang, 324000, P.R. China
| | - Weiwei Wang
- Department of Rehabilitation, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221002, P.R. China.,School of Medical Technology, Xuzhou Medical University, Xuzhou, Jiangsu 221004, P.R. China
| | - Jie Xiang
- Department of Rehabilitation, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221002, P.R. China.,School of Medical Technology, Xuzhou Medical University, Xuzhou, Jiangsu 221004, P.R. China
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24
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Lin B, Wang Y, Zhang P, Yuan Y, Zhang Y, Chen G. Gut microbiota regulates neuropathic pain: potential mechanisms and therapeutic strategy. J Headache Pain 2020; 21:103. [PMID: 32807072 PMCID: PMC7433133 DOI: 10.1186/s10194-020-01170-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 08/10/2020] [Indexed: 02/08/2023] Open
Abstract
Neuropathic pain (NP) is a sustained and nonreversible condition characterized by long-term devastating physical and psychological damage. Therefore, it is urgent to identify an effective treatment for NP. Unfortunately, the precise pathogenesis of NP has not been elucidated. Currently, the microbiota-gut-brain axis has drawn increasing attention, and the emerging role of gut microbiota is investigated in numerous diseases including NP. Gut microbiota is considered as a pivotal regulator in immune, neural, endocrine, and metabolic signaling pathways, which participates in forming a complex network to affect the development of NP directly or indirectly. In this review, we conclude the current understanding of preclinical and clinical findings regarding the role of gut microbiota in NP and provide a novel therapeutic method for pain relief by medication and dietary interventions.
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Affiliation(s)
- Binbin Lin
- Department of Anesthesiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, 3 Qingchun East Road, Zhejiang, 310016, Hangzhou, China
| | - Yuting Wang
- Department of Anesthesiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, 3 Qingchun East Road, Zhejiang, 310016, Hangzhou, China
| | - Piao Zhang
- Department of Anesthesiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, 3 Qingchun East Road, Zhejiang, 310016, Hangzhou, China
| | - Yanyan Yuan
- Department of Anesthesiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, 3 Qingchun East Road, Zhejiang, 310016, Hangzhou, China
| | - Ying Zhang
- Department of Anesthesiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, 3 Qingchun East Road, Zhejiang, 310016, Hangzhou, China
| | - Gang Chen
- Department of Anesthesiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, 3 Qingchun East Road, Zhejiang, 310016, Hangzhou, China.
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25
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Silva CR, Melo BMS, Silva JR, Lopes AH, Pereira JA, Cecilio NT, Berlink J, Souza GG, Lucas G, Vogl T, Cunha FQ, Alves-Filho JC, Cunha TM. S100A9 plays a pivotal role in a mouse model of herpetic neuralgia via TLR4/TNF pathway. Brain Behav Immun 2020; 88:353-362. [PMID: 32243898 DOI: 10.1016/j.bbi.2020.03.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 03/18/2020] [Accepted: 03/29/2020] [Indexed: 02/01/2023] Open
Abstract
Herpetic neuralgia is a painful condition following herpes zoster disease, which results from Varicella-zoster virus reactivation in the dorsal or trigeminal sensory ganglia. Nevertheless, the pathophysiological mechanisms involved in herpetic neuralgia are not well understood. Recently, we identified, that neuroimmune-glia interactions in the sensory ganglion is a critical mechanism for the development of herpetic neuralgia. Here, we investigate the contribution of S100A9, a well-known pro-inflammatory molecule produced by myeloid cells, for the development of herpetic neuralgia using a murine model of HSV-1 infection. We found that cutaneous HSV-1 infection results in an increase of S100A9 expression in the Dorsal Root Ganglia (DRGs). Infiltrating neutrophils into the DRGs were the main source of S100A9 post HSV-1 infection. Functionally, genetic or pharmacological inhibition of S100A9 impairs the development of HSV-1 infection-induced mechanical pain hypersensitivity. Finally, we found that the pronociceptive role of S100A9 in herpetic neuralgia depends on the TLR4/TNF pathway. These results unraveled previously unknown mechanisms involved in the pathophysiology of herpetic neuralgia and indicate that S100A9 might be an important target for novel therapies aiming acute herpetic neuralgia.
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Affiliation(s)
- Cássia R Silva
- Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil; Graduated Program in Genetics and Biochemistry, Biotechnology Institute, Federal University of Uberlândia, 38408-100 Uberlândia MG, Brazil
| | - Bruno M S Melo
- Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Jaqueline R Silva
- Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Alexandre H Lopes
- Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Janaina A Pereira
- Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Nerry T Cecilio
- Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Jonilson Berlink
- Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil; Center for Biological and Health Sciences, Federal University of Western Bahia, Barreiras, Bahia, Brazil
| | - Giovani G Souza
- Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Guilherme Lucas
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Thomas Vogl
- Institute of Immunology, University of Münster, D-48149 Münster, Germany
| | - Fernando Q Cunha
- Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - José C Alves-Filho
- Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Thiago M Cunha
- Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.
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26
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Toll-like receptor 7 contributes to neuropathic pain by activating NF-κB in primary sensory neurons. Brain Behav Immun 2020; 87:840-851. [PMID: 32205121 PMCID: PMC7316623 DOI: 10.1016/j.bbi.2020.03.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 03/17/2020] [Accepted: 03/19/2020] [Indexed: 01/01/2023] Open
Abstract
Toll like receptor 7 (TLR7) is expressed in neurons of the dorsal root ganglion (DRG), but whether it contributes to neuropathic pain is elusive. We found that peripheral nerve injury caused by ligation of the fourth lumbar (L4) spinal nerve (SNL) or chronic constriction injury of sciatic nerve led to a significant increase in the expression of TLR7 at mRNA and protein levels in mouse injured DRG. Blocking this increase through microinjection of the adeno-associated virus (AAV) 5 expressing TLR7 shRNA into the ipsilateral L4 DRG alleviated the SNL-induced mechanical, thermal and cold pain hypersensitivities in both male and female mice. This microinjection also attenuated the SNL-induced increases in the levels of phosphorylated extracellular signal-regulated kinase ½ (p-ERK1/2) and glial fibrillary acidic protein (GFAP) in L4 dorsal horn on the ipsilateral side during both development and maintenance periods. Conversely, mimicking this increase through microinjection of AAV5 expressing full-length TLR7 into unilateral L3/4 DRGs led to elevations in the amounts of p-ERK1/2 and GFAP in the dorsal horn, augmented responses to mechanical, thermal and cold stimuli, and induced the spontaneous pain on the ipsilateral side in the absence of SNL. Mechanistically, the increased TLR7 activated the NF-κB signaling pathway through promoting the translocation of p65 into the nucleus and phosphorylation of p65 in the nucleus from the injured DRG neurons. Our findings suggest that DRG TLR7 contributes to neuropathic pain by activating NF-κB in primary sensory neurons. TLR7 may be a potential target for therapeutic treatment of this disorder.
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27
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Chernov AV, Hullugundi SK, Eddinger KA, Dolkas J, Remacle AG, Angert M, James BP, Yaksh TL, Strongin AY, Shubayev VI. A myelin basic protein fragment induces sexually dimorphic transcriptome signatures of neuropathic pain in mice. J Biol Chem 2020; 295:10807-10821. [PMID: 32532796 DOI: 10.1074/jbc.ra120.013696] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/11/2020] [Indexed: 02/06/2023] Open
Abstract
In the peripheral nerve, mechanosensitive axons are insulated by myelin, a multilamellar membrane formed by Schwann cells. Here, we offer first evidence that a myelin degradation product induces mechanical hypersensitivity and global transcriptomics changes in a sex-specific manner. Focusing on downstream signaling events of the functionally active 84-104 myelin basic protein (MBP(84-104)) fragment released after nerve injury, we demonstrate that exposing the sciatic nerve to MBP(84-104) via endoneurial injection produces robust mechanical hypersensitivity in female, but not in male, mice. RNA-seq and systems biology analysis revealed a striking sexual dimorphism in molecular signatures of the dorsal root ganglia (DRG) and spinal cord response, not observed at the nerve injection site. Mechanistically, intra-sciatic MBP(84-104) induced phospholipase C (PLC)-driven (females) and phosphoinositide 3-kinase-driven (males) phospholipid metabolism (tier 1). PLC/inositol trisphosphate receptor (IP3R) and estrogen receptor co-regulation in spinal cord yielded Ca2+-dependent nociceptive signaling induction in females that was suppressed in males (tier 2). IP3R inactivation by intrathecal xestospongin C attenuated the female-specific hypersensitivity induced by MBP(84-104). According to sustained sensitization in tiers 1 and 2, T cell-related signaling spreads to the DRG and spinal cord in females, but remains localized to the sciatic nerve in males (tier 3). These results are consistent with our previous finding that MBP(84-104)-induced pain is T cell-dependent. In summary, an autoantigenic peptide endogenously released in nerve injury triggers multisite, sex-specific transcriptome changes, leading to neuropathic pain only in female mice. MBP(84-104) acts through sustained co-activation of metabolic, estrogen receptor-mediated nociceptive, and autoimmune signaling programs.
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Affiliation(s)
- Andrei V Chernov
- Department of Anesthesiology, University of California, San Diego, La Jolla, California, USA .,Infectious & Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Swathi K Hullugundi
- Department of Anesthesiology, University of California, San Diego, La Jolla, California, USA.,Veterans Affairs San Diego Healthcare System, La Jolla, California, USA
| | - Kelly A Eddinger
- Department of Anesthesiology, University of California, San Diego, La Jolla, California, USA
| | - Jennifer Dolkas
- Department of Anesthesiology, University of California, San Diego, La Jolla, California, USA.,Veterans Affairs San Diego Healthcare System, La Jolla, California, USA
| | - Albert G Remacle
- Infectious & Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Mila Angert
- Department of Anesthesiology, University of California, San Diego, La Jolla, California, USA.,Veterans Affairs San Diego Healthcare System, La Jolla, California, USA
| | - Brian P James
- Infectious & Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Tony L Yaksh
- Department of Anesthesiology, University of California, San Diego, La Jolla, California, USA
| | - Alex Y Strongin
- Infectious & Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Veronica I Shubayev
- Department of Anesthesiology, University of California, San Diego, La Jolla, California, USA .,Veterans Affairs San Diego Healthcare System, La Jolla, California, USA
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28
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Habib AM, Nagi K, Thillaiappan NB, Sukumaran V, Akhtar S. Vitamin D and Its Potential Interplay With Pain Signaling Pathways. Front Immunol 2020; 11:820. [PMID: 32547536 PMCID: PMC7270292 DOI: 10.3389/fimmu.2020.00820] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 04/09/2020] [Indexed: 12/12/2022] Open
Abstract
About 50 million of the U.S. adult population suffer from chronic pain. It is a complex disease in its own right for which currently available analgesics have been deemed woefully inadequate since ~20% of the sufferers derive no benefit. Vitamin D, known for its role in calcium homeostasis and bone metabolism, is thought to be of clinical benefit in treating chronic pain without the side-effects of currently available analgesics. A strong correlation between hypovitaminosis D and incidence of bone pain is known. However, the potential underlying mechanisms by which vitamin D might exert its analgesic effects are poorly understood. In this review, we discuss pathways involved in pain sensing and processing primarily at the level of dorsal root ganglion (DRG) neurons and the potential interplay between vitamin D, its receptor (VDR) and known specific pain signaling pathways including nerve growth factor (NGF), glial-derived neurotrophic factor (GDNF), epidermal growth factor receptor (EGFR), and opioid receptors. We also discuss how vitamin D/VDR might influence immune cells and pain sensitization as well as review the increasingly important topic of vitamin D toxicity. Further in vitro and in vivo experimental studies will be required to study these potential interactions specifically in pain models. Such studies could highlight the potential usefulness of vitamin D either alone or in combination with existing analgesics to better treat chronic pain.
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Affiliation(s)
| | | | | | | | - Saghir Akhtar
- College of Medicine, QU Health, Qatar University, Doha, Qatar
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29
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Miller RJ, Malfait AM, Miller RE. The innate immune response as a mediator of osteoarthritis pain. Osteoarthritis Cartilage 2020; 28:562-571. [PMID: 31862470 PMCID: PMC6951330 DOI: 10.1016/j.joca.2019.11.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 11/20/2019] [Indexed: 02/08/2023]
Abstract
In this narrative review, we discuss the emerging role of innate immunity in osteoarthritis (OA) joint pain. First, we give a brief description of the pain pathway in the context of OA. Then we consider how neuro-immune signaling pathways may promote OA pain. First, activation of neuronal Pattern Recognition Receptors by mediators released in a damaged joint can result in direct excitation of nociceptors, as well as in production of chemokines and cytokines. Secondly, indirect neuro-immune signaling may occur when innate immune cells produce algogenic factors, including chemokines and cytokines, that act on the pain pathway. Neuro-immune crosstalk occurs at different levels of the pathway, starting in the joint but also in the innervating dorsal root ganglia and in the dorsal horn. Synovitis is characterized by recruitment of immune cells, including macrophages, mast cells, and CD4+ lymphocytes, which may contribute to nociceptor sensitization and OA pain through production of algogenic factors that amplify the activation of sensory neurons. We discuss examples where this scenario has been suggested by findings in human OA and in animal models. Overall, increasing evidence suggests that innate immune pathways play an initiating as well as facilitating role in pain, but information on how these pathways operate in OA remains limited. Since these innate pathways are eminently targetable, future studies in this area may provide fruitful leads towards a better management of symptomatic OA.
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30
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Miller YI, Navia-Pelaez JM, Corr M, Yaksh TL. Lipid rafts in glial cells: role in neuroinflammation and pain processing. J Lipid Res 2020; 61:655-666. [PMID: 31862695 PMCID: PMC7193960 DOI: 10.1194/jlr.tr119000468] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/06/2019] [Indexed: 12/27/2022] Open
Abstract
Activation of microglia and astrocytes secondary to inflammatory processes contributes to the development and perpetuation of pain with a neuropathic phenotype. This pain state presents as a chronic debilitating condition and affects a large population of patients with conditions like rheumatoid arthritis and diabetes, or after surgery, trauma, or chemotherapy. Here, we review the regulation of lipid rafts in glial cells and the role they play as a key component of neuroinflammatory sensitization of central pain signaling pathways. In this context, we introduce the concept of an inflammaraft (i-raft), enlarged lipid rafts harboring activated receptors and adaptor molecules and serving as an organizing platform to initiate inflammatory signaling and the cellular response. Characteristics of the inflammaraft include increased relative abundance of lipid rafts in inflammatory cells, increased content of cholesterol per raft, and increased levels of inflammatory receptors, such as toll-like receptor (TLR)4, adaptor molecules, ion channels, and enzymes in lipid rafts. This inflammaraft motif serves an important role in the membrane assembly of protein complexes, for example, TLR4 dimerization. Operating within this framework, we demonstrate the involvement of inflammatory receptors, redox molecules, and ion channels in the inflammaraft formation and the regulation of cholesterol and sphingolipid metabolism in the inflammaraft maintenance and disruption. Strategies for targeting inflammarafts, without affecting the integrity of lipid rafts in noninflammatory cells, may lead to developing novel therapies for neuropathic pain states and other neuroinflammatory conditions.
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Affiliation(s)
- Yury I Miller
- Departments of MedicineUniversity of California San Diego, La Jolla, CA. mailto:
| | | | - Maripat Corr
- Departments of MedicineUniversity of California San Diego, La Jolla, CA
| | - Tony L Yaksh
- Anesthesiology,University of California San Diego, La Jolla, CA
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31
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Chidambaran V, Ashton M, Martin LJ, Jegga AG. Systems biology-based approaches to summarize and identify novel genes and pathways associated with acute and chronic postsurgical pain. J Clin Anesth 2020; 62:109738. [PMID: 32058259 DOI: 10.1016/j.jclinane.2020.109738] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/26/2019] [Accepted: 01/25/2020] [Indexed: 12/15/2022]
Abstract
STUDY OBJECTIVE To employ systems biology-based machine learning to identify biologic processes over-represented with genetic variants (gene enrichment) implicated in post-surgical pain. DESIGN Informed systems biology based integrative computational analyses. SETTING Pediatric research and teaching institution. INTERVENTIONS Pubmed search (01/01/2001-10/31/2017) was performed to identify "training" genes associated with postoperative pain in humans. Candidate genes were identified and prioritized using Toppgene suite, based on functional enrichment using several gene ontology annotations, and curated gene sets associated with mouse phenotype-knockout studies. MEASUREMENTS Computationally top-ranked candidate genes and literature-curated genes were included in pathway enrichment analyses. Hierarchical clustering was used to visualize select functional enrichment results between the two phenotypes. MAIN RESULTS Literature review identified 38 training genes associated with postoperative pain and 31 with CPSP. We identified 2610 prioritized novel candidate genes likely associated with acute and chronic postsurgical pain, the top 10th percentile jointly enriched (p 0.05; Benjamini-Hochberg correction) several pathways, topmost being cAMP response element-binding protein and ion channel pathways. Heat maps demonstrated enrichment of inflammatory/drug metabolism processes in acute postoperative pain and immune mechanisms in CPSP. CONCLUSION High interindividual variability in pain responses immediately after surgery and risk for CPSP suggests genetic susceptibility. Lack of large homogenous sample sizes have led to underpowered genetic association studies. Systems biology can be leveraged to integrate genetic-level data with biologic processes to generate prioritized candidate gene lists and understand novel biological pathways involved in acute postoperative pain and CPSP. Such data would be key to informing future polygenic studies with targeted genome wide profiling. This study demonstrates the utility of functional annotation - based prioritization and enrichment approaches and identifies novel genes and unique/shared biological processes involved in acute and chronic postoperative pain. Results provide framework for future targeted genetic profiling of CPSP risk, to enable preventive and therapeutic approaches.
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Affiliation(s)
- Vidya Chidambaran
- Department of Anesthesiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
| | - Maria Ashton
- Department of Anesthesiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Lisa J Martin
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Anil G Jegga
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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Lim H, Lee J, You B, Oh JH, Mok HJ, Kim YS, Yoon BE, Kim BG, Back SK, Park JS, Kim KP, Schnaar RL, Lee SJ. GT1b functions as a novel endogenous agonist of toll-like receptor 2 inducing neuropathic pain. EMBO J 2020; 39:e102214. [PMID: 32030804 DOI: 10.15252/embj.2019102214] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 11/19/2019] [Accepted: 01/02/2020] [Indexed: 12/30/2022] Open
Abstract
Spinal cord microglia contribute to nerve injury-induced neuropathic pain. We have previously demonstrated that toll-like receptor 2 (TLR2) signaling is critical for nerve injury-induced activation of spinal cord microglia, but the responsible endogenous TLR2 agonist has not been identified. Here, we show that nerve injury-induced upregulation of sialyltransferase St3gal2 in sensory neurons leads to an increase in expression of the sialylated glycosphingolipid, GT1b. GT1b ganglioside is axonally transported to the spinal cord dorsal horn and contributes to characteristics of neuropathic pain such as mechanical and thermal hypersensitivity. Spinal cord GT1b functions as an TLR2 agonist and induces proinflammatory microglia activation and central sensitization. Pharmacological inhibition of GT1b synthesis attenuates nerve injury-induced spinal cord microglia activation and pain hypersensitivity. Thus, the St3gal2-GT1b-TLR2 axis may offer a novel therapeutic target for the treatment of neuropathic pain.
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Affiliation(s)
- Hyoungsub Lim
- Department of Neuroscience and Physiology, Dental Research Institute, BK21-Plus, School of Dentistry, Seoul National University, Seoul, Korea
| | - Jaesung Lee
- Department of Neuroscience and Physiology, Dental Research Institute, BK21-Plus, School of Dentistry, Seoul National University, Seoul, Korea
| | - Byunghyun You
- Department of Neuroscience and Physiology, Dental Research Institute, BK21-Plus, School of Dentistry, Seoul National University, Seoul, Korea
| | - Jae Hoon Oh
- Department of Chemistry, Seoul National University, Seoul, Korea
| | - Hyuck Jun Mok
- Department of Applied Chemistry, College of Applied Sciences, Kyung Hee University, Yongin, Korea
| | - Yoo Sung Kim
- Department of Molecular Biology, Dankook University, Cheonan, Korea
| | - Bo-Eun Yoon
- Department of Molecular Biology, Dankook University, Cheonan, Korea
| | - Byung Gon Kim
- Department of Brain Science and Neurology, Ajou University School of Medicine, Suwon, Korea
| | - Seung Keun Back
- Department of Biomedical Laboratory Science, College of Medical Science, Konyang University, Daejeon, Korea
| | - Jong-Sang Park
- Department of Chemistry, Seoul National University, Seoul, Korea
| | - Kwang Pyo Kim
- Department of Applied Chemistry, College of Applied Sciences, Kyung Hee University, Yongin, Korea
| | - Ronald L Schnaar
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sung Joong Lee
- Department of Neuroscience and Physiology, Dental Research Institute, BK21-Plus, School of Dentistry, Seoul National University, Seoul, Korea
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Woller SA, Choi SH, An EJ, Low H, Schneider DA, Ramachandran R, Kim J, Bae YS, Sviridov D, Corr M, Yaksh TL, Miller YI. Inhibition of Neuroinflammation by AIBP: Spinal Effects upon Facilitated Pain States. Cell Rep 2019; 23:2667-2677. [PMID: 29847797 DOI: 10.1016/j.celrep.2018.04.110] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 04/02/2018] [Accepted: 04/25/2018] [Indexed: 12/17/2022] Open
Abstract
Apolipoprotein A-I binding protein (AIBP) reduces lipid raft abundance by augmenting the removal of excess cholesterol from the plasma membrane. Here, we report that AIBP prevents and reverses processes associated with neuroinflammatory-mediated spinal nociceptive processing. The mechanism involves AIBP binding to Toll-like receptor-4 (TLR4) and increased binding of AIBP to activated microglia, which mediates selective regulation of lipid rafts in inflammatory cells. AIBP-mediated lipid raft reductions downregulate LPS-induced TLR4 dimerization, inflammatory signaling, and expression of cytokines in microglia. In mice, intrathecal injections of AIBP reduce spinal myeloid cell lipid rafts, TLR4 dimerization, neuroinflammation, and glial activation. Intrathecal AIBP reverses established allodynia in mice in which pain states were induced by the chemotherapeutic cisplatin, intraplantar formalin, or intrathecal LPS, all of which are pro-nociceptive interventions known to be regulated by TLR4 signaling. These findings demonstrate a mechanism by which AIBP regulates neuroinflammation and suggest the therapeutic potential of AIBP in treating preexisting pain states.
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Affiliation(s)
- Sarah A Woller
- Department of Anesthesiology, University of California, San Diego, La Jolla, CA, USA
| | - Soo-Ho Choi
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Eun Jung An
- Department of Life Sciences, Ewha Womans University, Seoul, Korea
| | - Hann Low
- Department of Lipoproteins and Atherosclerosis, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Dina A Schneider
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Roshni Ramachandran
- Department of Anesthesiology, University of California, San Diego, La Jolla, CA, USA
| | - Jungsu Kim
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Yun Soo Bae
- Department of Life Sciences, Ewha Womans University, Seoul, Korea
| | - Dmitri Sviridov
- Department of Lipoproteins and Atherosclerosis, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Maripat Corr
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Tony L Yaksh
- Department of Anesthesiology, University of California, San Diego, La Jolla, CA, USA
| | - Yury I Miller
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA.
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Peng Y, Zhang X, Zhang T, Grace PM, Li H, Wang Y, Li H, Chen H, Watkins LR, Hutchinson MR, Yin H, Wang X. Lovastatin inhibits Toll-like receptor 4 signaling in microglia by targeting its co-receptor myeloid differentiation protein 2 and attenuates neuropathic pain. Brain Behav Immun 2019; 82:432-444. [PMID: 31542403 DOI: 10.1016/j.bbi.2019.09.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/13/2019] [Accepted: 09/14/2019] [Indexed: 12/23/2022] Open
Abstract
There is growing interest in drug repositioning to find new therapeutic indications for drugs already approved for use in people. Lovastatin is an FDA approved drug that has been used clinically for over a decade as a lipid-lowering medication. While lovastatin is classically considered to act as a hydroxymethylglutaryl (HMG)-CoA reductase inhibitor, the present series of studies reveal a novel lovastatin effect, that being as a Toll-like receptor 4 (TLR4) antagonist. Lovastatin selectively inhibits lipopolysaccharide (LPS)-induced TLR4-NF-κB activation without affecting signaling by other homologous TLRs. In vitro biophysical binding and cellular thermal shift assay (CETSA) show that lovastatin is recognized by TLR4's coreceptor myeloid differentiation protein 2 (MD-2). This finding is supported by molecular dynamics simulations that lovastatin targets the LPS binding pocket of MD-2 and lovastatin binding stabilizes the MD-2 conformation. In vitro studies of BV-2 microglial cells revealed that lovastatin inhibits multiple effects of LPS, including activation of NFkB; mRNA expression of tumor necrosis factor-a, interleukin-6 and cyclo-oxygenase 2; production of nitric oxide and reactive oxygen species; as well as phagocytic activity. Furthermore, intrathecal delivery of lovastatin over lumbosacral spinal cord of rats attenuated both neuropathic pain from sciatic nerve injury and expression of the microglial activation marker CD11 in lumbar spinal cord dorsal horn. Given the well-established role of microglia and proinflammatory signaling in neuropathic pain, these data are supportive that lovastatin, as a TLR4 antagonist, may be productively repurposed for treating chronic pain.
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Affiliation(s)
- Yinghua Peng
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Animal and Plant Sciences, Chinese Academy of Agricultural Sciences, Changchun, Jilin 130112, China; Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Yantai University, Yantai 264005, China
| | - Xiaozheng Zhang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Tianshu Zhang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Peter M Grace
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Hongyuan Li
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Yibo Wang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Hang Li
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Hongqian Chen
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Linda R Watkins
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Mark R Hutchinson
- Discipline of Physiology, Adelaide Medical School, University of Adelaide, South Australia, Australia; ARC Centre of Excellence for Nanoscale Biophotonics, University of Adelaide, South Australia 5000, Australia
| | - Hang Yin
- School of Pharmaceutical Sciences, Tsinghua University-Peking University Joint Center for Life Sciences, Tsinghua University, Beijing 100082, China
| | - Xiaohui Wang
- Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Yantai University, Yantai 264005, China; Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China; Department of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, China.
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Miller RE, Scanzello CR, Malfait AM. An emerging role for Toll-like receptors at the neuroimmune interface in osteoarthritis. Semin Immunopathol 2019; 41:583-594. [PMID: 31612243 DOI: 10.1007/s00281-019-00762-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 09/09/2019] [Indexed: 12/31/2022]
Abstract
Osteoarthritis (OA) is a chronic progressive, painful disease of synovial joints, characterized by cartilage degradation, subchondral bone remodeling, osteophyte formation, and synovitis. It is now widely appreciated that the innate immune system, and in particular Toll-like receptors (TLRs), contributes to pathological changes in OA joint tissues. Furthermore, it is now also increasingly recognized that TLR signaling plays a key role in initiating and maintaining pain. Here, we reviewed the literature of the past 5 years with a focus on how TLRs may contribute to joint damage and pain in OA. We discuss biological effects of specific damage-associated molecular patterns (DAMPs) which act as TLR ligands in vitro, including direct effects on pain-sensing neurons. We then discuss the phenotype of transgenic mice that target TLR pathways, and provide evidence for a complex balance between pro- and anti-inflammatory signaling pathways activated by OA DAMPs. Finally, we summarize clinical evidence implicating TLRs in OA pathogenesis, including polymorphisms and surrogate markers of disease activity. Our review of the literature led us to propose a model where multi-directional crosstalk between connective tissue cells (chondrocytes, fibroblasts), innate immune cells, and sensory neurons in the affected joint may promote OA pathology and pain.
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Affiliation(s)
- Rachel E Miller
- Division of Rheumatology, Department of Internal Medicine, Rush University Medical Center, 1611 W Harrison Street, Chicago, IL, 60612, USA
| | - Carla R Scanzello
- Section of Rheumatology and Translational Musculoskeletal Research Center, Corporal Michael J. Crescenz Veterans Affairs Medical Center & Division of Rheumatology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Anne-Marie Malfait
- Division of Rheumatology, Department of Internal Medicine, Rush University Medical Center, 1611 W Harrison Street, Chicago, IL, 60612, USA.
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Macrophage Toll-like Receptor 9 Contributes to Chemotherapy-Induced Neuropathic Pain in Male Mice. J Neurosci 2019; 39:6848-6864. [PMID: 31270160 DOI: 10.1523/jneurosci.3257-18.2019] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 05/31/2019] [Accepted: 06/18/2019] [Indexed: 12/28/2022] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) remains a pressing clinical problem; however, our understanding of sexual dimorphism in CIPN remains unclear. Emerging studies indicate a sex-dimorphic role of Toll-like receptor 4 (TLR4) in driving neuropathic pain. In this study, we examined the role of TLR9 in CIPN induced by paclitaxel in WT and Tlr9 mutant mice of both sexes. Baseline pain sensitivity was not affected in either Tlr9 mutant male or female mice. Intraplantar and intrathecal injection of the TLR9 agonist ODN 1826 induced mechanical allodynia in both sexes of WT and Tlr4 KO mice but failed to do so in Tlr9 mutant mice. Moreover, Trpv1 KO or C-fiber blockade by resiniferatoxin failed to affect intraplantar ODN 1826-induced mechanical allodynia. Interestingly, the development of paclitaxel-evoked mechanical allodynia was attenuated by TLR9 antagonism or Tlr9 mutation only in male mice. Paclitaxel-induced CIPN caused macrophage infiltration to DRGs in both sexes, and this infiltration was not affected by Tlr9 mutation. Paclitaxel treatment also upregulated TNF and CXCL1 in macrophage cultures and DRG tissues in both sexes, but these changes were compromised by Tlr9 mutation in male animals. Intraplantar adoptive transfer of paclitaxel-activated macrophages evoked mechanical allodynia in both sexes, which was compromised by Tlr9 mutation or by treatment with TLR9 inhibitor only in male animals. Finally, TLR9 antagonism reduced paclitaxel-induced mechanical allodynia in female nude mice (T-cell and B-cell deficient). Together, these findings reveal sex-dimorphic macrophage TLR9 signaling in chemotherapy-induced neuropathic pain.SIGNIFICANCE STATEMENT Chemotherapy-induced peripheral neuropathy (CIPN) is a major side effect in cancer patients undergoing clinical chemotherapy treatment regimens. The role of sex dimorphism with regards to the mechanisms of CIPN and analgesia against CIPN remains unclear. Previous studies have found that the infiltration of immune cells, such as macrophages into DRGs and their subsequent activation promote CIPN. Interestingly, the contribution of microglia to CIPN appears to be limited. Here, we show that macrophage TLR9 signaling promotes CIPN in male mice only. This study suggests that pathways in macrophages may be sex-dimorphic in CIPN. Our findings provide new insights into the role of macrophage signaling mechanisms underlying sex dimorphism in CIPN, which may inspire the development of more precise and effective therapies.
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Long Noncoding RNA Expression Profile in BV2 Microglial Cells Exposed to Lipopolysaccharide. BIOMED RESEARCH INTERNATIONAL 2019; 2019:5387407. [PMID: 31309106 PMCID: PMC6594345 DOI: 10.1155/2019/5387407] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 05/26/2019] [Indexed: 02/07/2023]
Abstract
Neuropathic pain, which is one of the most common forms of chronic pain, seriously increases healthcare costs and impairs patients' quality of life with an incidence of 7–10% worldwide. Microglia cell activation plays a key role in the progression of neuropathic pain. Better understanding of novel molecules modulating microglia cell activation and these underlying functions will extremely benefit the exploration of new treatment. Recent studies suggested long noncoding RNAs may be involved in neuropathic pain. However, its underlying functions and mechanisms in microglia cell activation remain unclear. To identify the differentially expressed lncRNAs and predict their functions in the progression of microglia cell activation, GSE103156 was analyzed using integrated bioinformatics methods. The expression levels of selected lncRNAs and mRNAs were determined by real-time PCR. In the present study, a total of 56 lncRNAs and 298 mRNAs were significantly differentially expressed. The differentially expressed mRNAs were mainly enriched in NF-kappa B signaling pathway, TNF signaling pathway, Toll-like receptor signaling pathway, and NOD-like receptor signaling pathway. The top 10 hub genes were Tnf, Il6, Stat1, Cxcl10, Il1b, Tlr2, Irf1, Ccl2, Irf7, and Ccl5 in the PPI network. Our results showed that Gm8989, Gm8979, and AV051173 may be involved in the progression of microglia cell activation. Taken together, our findings suggest that lots of lncRNAs may be involved in BV2 microglia cell activation in vitro. The findings may provide relevant information for the development of promising targets for the microglial cells activation of neuropathic pain in vivo in the future.
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Akgün E, Lunzer MM, Portoghese PS. Combined Glia Inhibition and Opioid Receptor Agonism Afford Highly Potent Analgesics without Tolerance. ACS Chem Neurosci 2019; 10:2004-2011. [PMID: 30110531 DOI: 10.1021/acschemneuro.8b00323] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Commonly prescribed opioid analgesics produce tolerance upon chronic use due in part to induction of hyperalgesia. Given that two reported bivalent ligands (MMG22 and MCC22) produce potent antinociception without tolerance only in inflamed mice, we have investigated the possible cellular and receptor targets of these ligands. The selective microglia inhibitors, minocycline and SB290157, antagonized intrathecal (i.t.) MCC22 antinociception orders of magnitude more potently than MMG22, suggesting that MCC22 selectively targets activated microglia. The astrocyte toxin, l-α-aminoadipic acid antagonized MMG22 antinociception 126-fold without reducing the potency of MCC22, indicating that activated astrocytes are targets of MMG22. MK-801 and Ro25-6981 antagonism of MMG22 antinociception, but not MCC22, is consistent with selective inhibition of activated NMDAR in astrocytes. The antinociception produced by i.t. MMG22 or MCC22 were both antagonized by the selective mu opioid receptor antagonist, β-FNA, implicating interaction of these ligands with MOR in spinal afferent neurons. MCC22 antinociception was potently blocked by kainate or AMPA ion channel antagonists (LY382884; NBQX), in contrast to MMG22. It is concluded that i.t. MMG22 and MCC22 produce exceptional antinociception via potent inhibition of activated spinal glia, thereby leading to desensitization of spinal neurons and enhanced activation of neuronal MOR. Thus, the present study suggests a new approach to treatment of chronic inflammatory pain without tolerance through a single molecular entity that simultaneously inhibits activated glia and stimulates MOR in spinal neurons.
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Affiliation(s)
- Eyup Akgün
- Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Mary M. Lunzer
- Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Philip S. Portoghese
- Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States
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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: 13] [Impact Index Per Article: 2.6] [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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40
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Woller SA, Ocheltree C, Wong SY, Bui A, Fujita Y, Gonçalves Dos Santos G, Yaksh TL, Corr M. Neuraxial TNF and IFN-beta co-modulate persistent allodynia in arthritic mice. Brain Behav Immun 2019; 76:151-158. [PMID: 30465880 PMCID: PMC6396982 DOI: 10.1016/j.bbi.2018.11.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Revised: 11/03/2018] [Accepted: 11/18/2018] [Indexed: 02/06/2023] Open
Abstract
In rheumatoid arthritis, joint pain can persist despite resolution of swelling. Similarly, in the murine K/BxN serum transfer model, a persistent tactile allodynia is observed after the resolution of joint inflammation (post-inflammatory pain) in male mice. Here, we found female wild type (WT) mice show inflammatory, but reduced post-inflammatory tactile allodynia. The transition to the post-inflammatory phenotype is dependent on TLR4 signaling. At the spinal level, we found differences in TNF and IFNβ mRNA expression in WT and TLR4 deficient males. In wild type male and female mice, there is differential temporal spinal expression of TNF and IFNβ. In WT males, blockade of TNF or administration of IFNβ was insufficient to affect the persistent allodynia. However, co-administration of intrathecal (IT) IFNβ and anti-TNF antibodies in male WT mice permanently reversed tactile allodynia. IT IFNβ treatment induces expression of anti-inflammatory proteins, contributing to the beneficial effect. Together, these experiments illustrated differences in the transition to chronic tactile allodynia in male and female animals and the complexities of effective pharmacologic interventions.
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Affiliation(s)
- Sarah A Woller
- Departments of Anesthesiology, University of California, San Diego, La Jolla, CA, USA
| | - Cody Ocheltree
- Division of Rheumatology, Allergy and Immunology, University of California, San Diego, La Jolla, CA, USA
| | - Stephanie Y Wong
- Division of Rheumatology, Allergy and Immunology, University of California, San Diego, La Jolla, CA, USA
| | - Anthony Bui
- Division of Rheumatology, Allergy and Immunology, University of California, San Diego, La Jolla, CA, USA
| | - Yuya Fujita
- Division of Rheumatology, Allergy and Immunology, University of California, San Diego, La Jolla, CA, USA
| | | | - Tony L Yaksh
- Departments of Anesthesiology, University of California, San Diego, La Jolla, CA, USA
| | - Maripat Corr
- Division of Rheumatology, Allergy and Immunology, University of California, San Diego, La Jolla, CA, USA.
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41
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Essential roles of C-type lectin Mincle in induction of neuropathic pain in mice. Sci Rep 2019; 9:872. [PMID: 30696945 PMCID: PMC6351622 DOI: 10.1038/s41598-018-37318-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 12/05/2018] [Indexed: 11/09/2022] Open
Abstract
Increasing evidence indicates that pattern recognition receptors (PRRs) are involved in neuropathic pain after peripheral nerve injury (PNI). While a significant number of studies support an association between neuropathic pain and the innate immune response mediated through Toll-like receptors, a family of PRRs, the roles of other types of PRRs are largely unknown. In this study, we have focused on the macrophage-inducible C-type lectin (Mincle), a PRR allocated to the C-type lectin receptor family. Here, we show that Mincle is involved in neuropathic pain after PNI. Mincle-deficient mice showed impaired PNI-induced mechanical allodynia. After PNI, expression of Mincle mRNA was rapidly increased in the injured spinal nerve. Most Mincle-expressing cells were identified as infiltrating leucocytes, although the migration of leucocytes was also observed in Mincle-deficient mice. Furthermore, Mincle-deficiency affected the induction of genes, which are reported to contribute to neuropathic pain after PNI in the dorsal root ganglia and spinal dorsal horn. These results suggest that Mincle is involved in triggering sequential processes that lead to the pathogenesis of neuropathic pain.
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42
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Ramachandran R, Wang Z, Saavedra C, DiNardo A, Corr M, Powell SB, Yaksh TL. Role of Toll-like receptor 4 signaling in mast cell-mediated migraine pain pathway. Mol Pain 2019; 15:1744806919867842. [PMID: 31342858 PMCID: PMC6688145 DOI: 10.1177/1744806919867842] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 05/09/2019] [Accepted: 06/04/2019] [Indexed: 01/27/2023] Open
Abstract
Degranulation of meningeal mast cells leading to the sensitization of trigeminal vascular afferent processing is believed to be one of the mechanisms underlying the migraine pain pathway. Recent work suggests that Toll-like receptor 4 (TLR4) may be involved in signaling states of central sensitization. Using a murine model of light aversion produced by compound 48/80 (2 mg/kg, intraperitoneal) mast cell degranulation, employed as a surrogate marker for photophobia observed in migraineurs, we examined the role of TLR4 in migraine-like behavior and neuronal activation. Using a two-chambered light/dark box, we found that compound 48/80 administration in male and female C57Bl/6 mice produced light aversion lasting up to 2 h, and that pre-treatment with sumatriptan (1 mg/kg, i.p.) reliably prevented this effect. Genetic deletion and pharmacological blockade of TLR4 with TAK-242 (3 mg/kg, i.p.) reversed the light aversive effects of compound 48/80 in males but not in females. Assessing the downstream signaling pathway in mutant mice, we found that the TLR4-mediated, light aversion was dependent upon myeloid differentiation primary response gene 88 but not Toll-interleukin-1 receptor domain-containing adapter-inducing interferon-β signaling. In separate groups, male mice sacrificed at 10 min following compound 48/80 revealed a significant increase in the incidence of evoked p-extracellular signal–regulated kinases (+) neurons in the nucleus caudalis of wild type but not Tlr4−/− mice or in mice pre-treated with sumatriptan. This study thus provides the first evidence for involvement of TLR4 signaling through MyD88 in initiating and maintaining migraine-like behavior and nucleus caudalis neuronal activation in the mouse.
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Affiliation(s)
- Roshni Ramachandran
- Department of Anesthesiology, University of California
San Diego, La Jolla CA, USA
| | - Zhenping Wang
- Department of Dermatology, University of California
San Diego, La Jolla, CA, USA
| | - Christian Saavedra
- Department of Anesthesiology, University of California
San Diego, La Jolla CA, USA
| | - Anna DiNardo
- Department of Dermatology, University of California
San Diego, La Jolla, CA, USA
| | - Maripat Corr
- Division of Rheumatology, Allergy, and Immunology,
University of California San Diego, La Jolla, CA, USA
| | - Susan B Powell
- Department of Psychiatry, University of California San
Diego, La Jolla, CA, USA
| | - Tony L Yaksh
- Department of Anesthesiology, University of California
San Diego, La Jolla CA, USA
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43
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Bruno K, Woller SA, Miller YI, Yaksh TL, Wallace M, Beaton G, Chakravarthy K. Targeting toll-like receptor-4 (TLR4)-an emerging therapeutic target for persistent pain states. Pain 2018; 159:1908-1915. [PMID: 29889119 PMCID: PMC7890571 DOI: 10.1097/j.pain.0000000000001306] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Toll-like receptors (TLRs) are a family of pattern recognition receptors that initiate signaling in innate and adaptive immune pathways. The highly conserved family of transmembrane proteins comprises an extracellular domain that recognizes exogenous and endogenous danger molecules and an ectodomain that activates downstream pathways in response. Recent studies suggest that continuous activation or dysregulation of TLR signaling may contribute to chronic disease states. The receptor is located not only on inflammatory cells (meningeal and peripheral macrophages) but on neuraxial glia (microglia and astrocytes), Schwann cells, fibroblasts, dorsal root ganglia, and dorsal horn neurons. Procedures blocking TLR functionality have shown pronounced effects on pain behavior otherwise observed in models of chronic inflammation and nerve injury. This review addresses the role of TLR4 as an emerging therapeutic target for the evolution of persistent pain and its role in noncanonical signaling, mediating anomalous pro-algesic actions of opiates. Accordingly, molecules targeting inhibition of this receptor have promise as disease-modifying and opioid-sparing alternatives for persistent pain states.
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Affiliation(s)
- Kelly Bruno
- Department of Anesthesiology and Pain Medicine, University of California San Diego Health Sciences, La Jolla, CA, USA
- VA San Diego Healthcare System, San Diego, CA, USA
- Center for Excellence in Stress and Mental Health, VA San Diego Healthcare System, San Diego, CA, USA
| | - Sarah A. Woller
- Department of Anesthesiology and Pain Medicine, University of California San Diego Health Sciences, La Jolla, CA, USA
| | - Yury I. Miller
- Department of Medicine, University of California San Diego Health Science, La Jolla, CA, USA
| | - Tony L. Yaksh
- Department of Anesthesiology and Pain Medicine, University of California San Diego Health Sciences, La Jolla, CA, USA
- Douleur Therapeutics, 10225 Barnes Canyon Road, Suite A104, San Diego, CA, USA
| | - Mark Wallace
- Department of Anesthesiology and Pain Medicine, University of California San Diego Health Sciences, La Jolla, CA, USA
- Douleur Therapeutics, 10225 Barnes Canyon Road, Suite A104, San Diego, CA, USA
| | - Graham Beaton
- Douleur Therapeutics, 10225 Barnes Canyon Road, Suite A104, San Diego, CA, USA
| | - Krishnan Chakravarthy
- Department of Anesthesiology and Pain Medicine, University of California San Diego Health Sciences, La Jolla, CA, USA
- VA San Diego Healthcare System, San Diego, CA, USA
- Douleur Therapeutics, 10225 Barnes Canyon Road, Suite A104, San Diego, CA, USA
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Dodds KN, Beckett EAH, Evans SF, Hutchinson MR. Spinal Glial Adaptations Occur in a Minimally Invasive Mouse Model of Endometriosis: Potential Implications for Lesion Etiology and Persistent Pelvic Pain. Reprod Sci 2018; 26:357-369. [PMID: 29730970 DOI: 10.1177/1933719118773405] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Glial adaptations within the central nervous system are well known to modulate central sensitization and pain. Recently, it has been suggested that activity of glial-related proinflammatory cytokines may potentiate peripheral inflammation, via central neurogenic processes. However, a role for altered glial function has not yet been investigated in the context of endometriosis, a chronic inflammatory condition in women associated with peripheral lesions, often manifesting with persistent pelvic pain. Using a minimally invasive mouse model of endometriosis, we investigated associations between peripheral endometriosis-like lesions and adaptations in central glial reactivity. Spinal cords (T13-S1) from female C57BL/6 mice with endometriosis-like lesions (ENDO) were imaged via fluorescent immunohistochemistry for the expression of glial fibrillary acidic protein (GFAP; astrocytes) and CD11b (microglia) in the dorsal horn (n = 5). Heightened variability ( P = .02) as well as an overall increase ( P = .04) in the mean area of GFAP immunoreactivity was found in ENDO versus saline-injected control animals. Interestingly, spinal levels showing the greatest alterations in GFAP immunoreactivity appeared to correlate with the spatial location of lesions within the abdominopelvic cavity. A subtle but significant increase in the mean area of CD11b immunostaining was also observed in ENDO mice compared to controls ( P = .02). This is the first study to describe adaptations in nonneuronal, immune-like cells of the central nervous system attributed to the presence of endometriosis-like lesions.
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Affiliation(s)
- Kelsi N Dodds
- 1 Discipline of Physiology, Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Elizabeth A H Beckett
- 1 Discipline of Physiology, Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Susan F Evans
- 2 Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Mark R Hutchinson
- 1 Discipline of Physiology, Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia.,3 Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, University of Adelaide, Adelaide, South Australia, Australia
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Early life vincristine exposure evokes mechanical pain hypersensitivity in the developing rat. Pain 2018; 158:1647-1655. [PMID: 28722694 DOI: 10.1097/j.pain.0000000000000953] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Vincristine (VNC) is commonly used to treat pediatric cancers, including the most prevalent childhood malignancy, acute lymphoblastic leukemia. Although clinical evidence suggests that VNC causes peripheral neuropathy in children, the degree to which pediatric chemotherapeutic regimens influence pain sensitivity throughout life remains unclear, in part because of the lack of an established animal model of chemotherapy-induced neuropathic pain during early life. Therefore, this study investigated the effects of VNC exposure between postnatal days (P) 11 and 21 on mechanical and thermal pain sensitivity in the developing rat. Low doses of VNC (15 or 30 μg/kg) failed to alter nociceptive withdrawal reflexes at any age examined compared with vehicle-injected littermate controls. Meanwhile, high dose VNC (60 μg/kg) evoked mechanical hypersensitivity in both sexes beginning at P26 that persisted until adulthood and included both static and dynamic mechanical allodynia. Hind paw withdrawal latencies to noxious heat and cold were unaffected by high doses of VNC, suggesting a selective effect of neonatal VNC on mechanical pain sensitivity. Gross and fine motor function appeared normal after VNC treatment, although a small decrease in weight gain was observed. The VNC regimen also produced a significant decrease in intraepidermal nerve fiber density in the hind paw skin by P33. Overall, the present results demonstrate that high-dose administration of VNC during the early postnatal period selectively evokes a mechanical hypersensitivity that is slow to emerge during adolescence, providing further evidence that aberrant sensory input during early life can have prolonged consequences for pain processing.
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Matsuura W, Harada S, Liu K, Nishibori M, Tokuyama S. Evidence of a role for spinal HMGB1 in ischemic stress-induced mechanical allodynia in mice. Brain Res 2018; 1687:1-10. [DOI: 10.1016/j.brainres.2018.02.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 02/13/2018] [Accepted: 02/17/2018] [Indexed: 10/18/2022]
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47
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Hu TT, Wang RR, Tang YY, Wu YX, Yu J, Hou WW, Lou GD, Zhou YD, Zhang SH, Chen Z. TLR4 deficiency abrogated widespread tactile allodynia, but not widespread thermal hyperalgesia and trigeminal neuropathic pain after partial infraorbital nerve transection. Pain 2017; 159:273-283. [DOI: 10.1097/j.pain.0000000000001100] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Abstract
One of the fundamental mechanisms whereby the innate immune system coordinates inflammatory signal transduction is through Toll-like receptors (TLRs), which function to protect and defend the host organism by initiating inflammatory signaling cascades in response to tissue damage or injury. TLRs are positioned at the neuroimmune interface, and accumulating evidence suggests that the inflammatory consequences of TLR activation on glia (including microglia and astrocytes), sensory neurons, and other cell types can influence nociceptive processing and lead to states of exaggerated and unresolved pain. In this review, we summarize our current understanding of how different TLRs and their accessory or adaptor molecules can contribute to the development and maintenance of persistent pain. The challenges and opportunities of targeting TLRs for new treatment strategies against chronic pain are discussed, including the therapeutic context of TLR-mediated signaling in opioid analgesia and chemotherapy-induced pain. Considering the prevalence of persistent pain and the insufficient efficacy and safety of current treatment options, a deeper understanding of Toll-like receptors holds the promise of novel therapies for managing pathological pain.
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Reins RY, Courson J, Lema C, Redfern RL. MyD88 contribution to ocular surface homeostasis. PLoS One 2017; 12:e0182153. [PMID: 28796783 PMCID: PMC5552092 DOI: 10.1371/journal.pone.0182153] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 07/13/2017] [Indexed: 12/18/2022] Open
Abstract
The cornea must maintain homeostasis, enabling rapid response to injury and microbial insult, to protect the eye from insult and infection. Toll-like receptors (TLRs) are critical to this innate immune response through the recognition and response to pathogens. Myeloid differentiation primary response (MyD88) is a key signaling molecule necessary for Toll-like receptor (TLR) and interleukin-1 receptor (IL-1R)-mediated immune defense and has been shown to be necessary for corneal defense during infection. Here, we examined the intrinsic role of TLR signaling in ocular surface tissues by determining baseline levels of inflammatory mediators, the response to mechanical stimuli, and corneal infection in MyD88-deficient mice (MyD88-/-). In addition, cytokine, chemokine, and matrix metalloproteinase (MMP) expression was determined in ocular surface cells exposed to a panel of TLR agonists. Compared to wild-type (WT) animals, MyD88-/- mice expressed lower MMP-9 levels in the cornea and conjunctiva. Corneal IL-1α, TNFα, and conjunctival IL-1α, IL-2, IL-6, and IL-9 levels were also significantly reduced. Additionally, CXCL1 and RANTES expression was lower in both MyD88-/- tissues compared to WT and IL-1R-/- mice. Interestingly, MyD88-/- mice had lower corneal sensitivities (1.01±0.31 gm/mm2) than both WT (0.59±0.16 gm/mm2) and IL-1R-/- (0.52±0.08 gm/mm2). Following Pseudomonas aeruginosa challenge, MyD88-/- mice had better clinical scores (0.5±0.0) compared to IL-1R-/- (1.5±0.6) and WT (2.3±0.3) animals, but had significantly more corneal bacterial isolates. However, no signs of infection were detected in inoculated uninjured corneas from either MyD88 or IL-1R-deficient mice. This work furthers our understanding of the importance of TLR signaling in corneal defense and immune homeostasis, showing that a lack of MyD88 may compromise the baseline innate response to insult.
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Affiliation(s)
- Rose Y. Reins
- The Ocular Surface Institute, College of Optometry, University of Houston, Houston, Texas, United States of America
| | - Justin Courson
- The Ocular Surface Institute, College of Optometry, University of Houston, Houston, Texas, United States of America
| | - Carolina Lema
- The Ocular Surface Institute, College of Optometry, University of Houston, Houston, Texas, United States of America
| | - Rachel L. Redfern
- The Ocular Surface Institute, College of Optometry, University of Houston, Houston, Texas, United States of America
- * E-mail:
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50
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Allette YM, Kim Y, Randolph AL, Smith JA, Ripsch MS, White FA. Decoy peptide targeted to Toll-IL-1R domain inhibits LPS and TLR4-active metabolite morphine-3 glucuronide sensitization of sensory neurons. Sci Rep 2017. [PMID: 28623271 PMCID: PMC5473853 DOI: 10.1038/s41598-017-03447-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Accumulating evidence indicates that Toll-like receptor (TLR) signaling adapter protein interactions with Toll/Interleukin-1 Receptor (TIR) domains present in sensory neurons may modulate neuropathic pain states. Following ligand interaction with TLRs, TIR serves to both initiate intracellular signaling and facilitate recruitment of signaling adapter proteins to the intracytoplasmic domain. Although TLR TIR is central to a number of TLR signaling cascades, its role in sensory neurons is poorly understood. In this study we investigated the degree to which TLR TIR decoy peptide modified to include a TAT sequence (Trans-Activator of Transcription gene in HIV; TAT-4BB) affected LPS-induced intracellular calcium flux and excitation in sensory neurons, and behavioral changes due to TLR4 active metabolite, morphine-3-glucuronide (M3G) exposure in vivo. TAT-4BB inhibited LPS-induced calcium changes in a majority of sensory neurons and decreased LPS-dependent neuronal excitability in small diameter neurons. Acute systemic administration of the TAT-4BB reversed M3G-induced tactile allodynia in a dose-dependent manner but did not affect motor activity, anxiety or responses to noxious thermal stimulus. These data suggest that targeting TLR TIR domains may provide novel pharmacological targets to reduce or reverse TLR4-dependent pain behavior in the rodent.
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Affiliation(s)
- Yohance M Allette
- Medical Science Training Program, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Youngsook Kim
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Aaron L Randolph
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.,Research and Development Services, Richard L. Roudebush VA Medical Center, Indianapolis, IN, 46202, USA
| | - Jared A Smith
- Medical Science Training Program, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Matthew S Ripsch
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.,Research and Development Services, Richard L. Roudebush VA Medical Center, Indianapolis, IN, 46202, USA
| | - Fletcher A White
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA. .,Research and Development Services, Richard L. Roudebush VA Medical Center, Indianapolis, IN, 46202, USA.
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