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Zhang Y, Wang B, Feng X, Wang H, Gao J, Li X, Huo X, Yasin B, Bekker A, Hu H, Tao YX. RNA-binding protein SYNCRIP contributes to neuropathic pain through stabilising CCR2 expression in primary sensory neurones. Br J Anaesth 2024:S0007-0912(24)00466-5. [PMID: 39244479 DOI: 10.1016/j.bja.2024.07.024] [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: 02/25/2024] [Revised: 07/23/2024] [Accepted: 07/31/2024] [Indexed: 09/09/2024] Open
Abstract
BACKGROUND Nerve injury-induced changes in gene expression in the dorsal root ganglion (DRG) contribute to the genesis of neuropathic pain. SYNCRIP, an RNA-binding protein, is critical for the stabilisation of gene expression. Whether SYNCRIP participates in nerve injury-induced alterations in DRG gene expression and nociceptive hypersensitivity is unknown. METHODS The expression and distribution of SYNCRIP in mouse DRG after chronic constriction injury (CCI) of the unilateral sciatic nerve were assessed. Effect of microinjection of Syncrip small interfering RNA into the ipsilateral L3 and L4 DRGs on the CCI-induced upregulation of chemokine (C-C motif) receptor 2 (CCR2) and nociceptive hypersensitivity were examined. Additionally, effects of microinjection of adeno-associated virus 5 expressing full length Syncrip mRNA (AAV5-Syncrip) on basal DRG CCR2 expression and nociceptive thresholds were observed. RESULTS SYNCRIP is expressed predominantly in DRG neurones, where it co-exists with CCR2. Levels of Syncrip mRNA and SYNCRIP protein in injured DRG increased time-dependently on days 3-14 after CCI. Blocking this increase through microinjection of Syncrip small interfering RNA into injured DRG attenuated CCI-induced upregulation of DRG CCR2 and development and maintenance of nociceptive hypersensitivities. Mimicking this increase through DRG microinjection of AAV5-Syncrip elevated CCR2 expression in microinjected DRGs, enhanced the responses to mechanical, heat, and cold stimuli, and induced ongoing pain in naive mice. Mechanistically, SYNCRIP bound to 3-UTR of Ccr2 mRNA and stabilised its expression in DRG neurones. CONCLUSIONS SYNCRIP contributes to the induction and maintenance of neuropathic pain likely through stabilising expression of CCR2 in injured DRG. SYNCRIP may be a potential target for treating this disorder.
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Affiliation(s)
- Yang Zhang
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Bing Wang
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Xiaozhou Feng
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Huixing Wang
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Ju Gao
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Xu Li
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Xiaodong Huo
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Bushra Yasin
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Alex Bekker
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Huijuan Hu
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA; Department of Physiology, Pharmacology & Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Yuan-Xiang Tao
- Department of Anesthesiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA; Department of Physiology, Pharmacology & Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA; Department of Cell Biology & Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA.
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Kim SI, Yang J, Shin J, Shin N, Shin HJ, Lee J, Noh C, Kim DW, Lee SY. Amitriptyline nanoparticle repositioning prolongs the anti-allodynic effect of enhanced microglia targeting. Nanomedicine (Lond) 2024:1-14. [PMID: 39229790 DOI: 10.1080/17435889.2024.2390349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 08/06/2024] [Indexed: 09/05/2024] Open
Abstract
Aim: Amitriptyline (AMI) has been used to treat neuropathic pain. However, the clinical outcomes remain unsatisfactory, presumably due to a limited understanding of the underlying molecular mechanisms. Here, we investigated a drug repositioning strategy using a low-dose of AMI encapsulated in poly (D, L lactic-co-glycolic acid) (PLGA) nanoparticles (AMI NPs) for neuropathic pain, since PLGA nanoparticles are known to enhance delivery to microglia.Methods: We evaluated the anti-allodynic effects of AMI and AMI NPs on neuropathic pain by assessing behaviors and inflammatory responses in a rat model of spinal nerve ligation (SNL). While the anti-allodynic effect of AMI (30 μg) drug injection on SNL-induced neuropathic pain persisted for 12 h, AMI NPs significantly alleviated mechanical allodynia for 3 days.Results: Histological and cytokine analyses showed AMI NPs facilitated the reduction of microglial activation and pro-inflammatory mediators in the spinal dorsal horn. This study suggests that AMI NPs can provide a sustained anti-allodynic effect by enhancing the targeting of microglia and regulating the release of pro-inflammatory cytokines from activated microglia.Conclusion: Our findings suggest that the use of microglial-targeted NPs continuously releasing AMI (2 μg) as a drug repositioning strategy offers long-term anti-allodynic effects.
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Affiliation(s)
- Song I Kim
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
- Department of Anatomy & Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
| | - Jiah Yang
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Juhee Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
- Department of Anatomy & Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
| | - Nara Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
- Department of Anatomy & Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
| | - Hyo Jung Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
- Department of Anatomy & Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
| | - Jiyong Lee
- Department of Anesthesia & Pain Medicine, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
| | - Chan Noh
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Dong Woon Kim
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
- Department of Anatomy & Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
| | - Sun Yeul Lee
- Department of Anesthesia & Pain Medicine, Chungnam National University School of Medicine, Daejeon, 35015, Republic of Korea
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Li L, Liu Y, Hu W, Yang J, Ma S, Tian Z, Cao Z, Pan K, Jiang M, Liu X, Wu S, Luo C, Xie RG. Peripheral CCL2 induces inflammatory pain via regulation of Ih currents in small diameter DRG neurons. Front Mol Neurosci 2023; 16:1144614. [PMID: 37860084 PMCID: PMC10582564 DOI: 10.3389/fnmol.2023.1144614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 09/14/2023] [Indexed: 10/21/2023] Open
Abstract
The C-C motif chemokine ligand 2 (CCL2) has been implicated in chronic pain, but its exact mechanism of peripheral sensitization is unknown. In this study, we aimed to clarify the mechanism of CCL2 regulation of ion channels. Our behavioral experiments revealed that ZD7288, a blocker of Ih current, can inhibit CFA and CCL2-mediated mechanical and thermal nociceptive sensitization. Furthermore, patch clamp studies demonstrated that CFA-induced peripheral sensitization primarily affects the excitability of small-diameter DRG neurons. Further studies revealed that inflammatory pain caused by CFA or incubation of DRG with CCL2 mainly affected Ih currents in small-diameter DRG neurons, which were blocked by co-incubation CCR2 antagonist INCB3344 or adenylate cyclase inhibitor SQ22536. Immunohistochemical staining showed that both intraplantar injection of CFA as well as DRG injection of CCL2 resulted in significant upregulation of CCR2+/HCN2+ expression. In conclusion, we suggest in the inflammatory pain state, CCL2 can act on small-diameter DRG neurons, leading to upregulation of HCN2 expression and consequently Ih, which in turn leads to neuronal hyperexcitability.
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Affiliation(s)
- Lamei Li
- Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, Xi’an, China
- School of Life Sciences & Research Center for Resource Peptide Drugs, Shaanxi Engineering & Technological Research Center for Conversation & Utilization of Regional Biological Resources, Yan’an University, Yan’an, China
| | - Yuanying Liu
- Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, Xi’an, China
- School of Life Sciences & Research Center for Resource Peptide Drugs, Shaanxi Engineering & Technological Research Center for Conversation & Utilization of Regional Biological Resources, Yan’an University, Yan’an, China
| | - Wenchao Hu
- Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Jing Yang
- Heart Hospital, Xi’an International Medical Center Hospital, Xi’an, China
| | - Suibin Ma
- Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Zhicheng Tian
- Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Zixuan Cao
- No.6 Cadet Regiment, School of Basic Medical Sciences, Fourth Military Medical University, Xi’an, China
| | - Kunqing Pan
- No.19 Cadet Regiment, School of Basic Medical Sciences, Fourth Military Medical University, Xi’an, China
| | - Ming Jiang
- School of Life Sciences & Research Center for Resource Peptide Drugs, Shaanxi Engineering & Technological Research Center for Conversation & Utilization of Regional Biological Resources, Yan’an University, Yan’an, China
| | - Xia Liu
- School of Life Sciences & Research Center for Resource Peptide Drugs, Shaanxi Engineering & Technological Research Center for Conversation & Utilization of Regional Biological Resources, Yan’an University, Yan’an, China
| | - Shengxi Wu
- Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Ceng Luo
- Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Rou-Gang Xie
- Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, Xi’an, China
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Bravo-Caparrós I, Ruiz-Cantero MC, Perazzoli G, Cronin SJF, Vela JM, Hamed MF, Penninger JM, Baeyens JM, Cobos EJ, Nieto FR. Sigma-1 receptors control neuropathic pain and macrophage infiltration into the dorsal root ganglion after peripheral nerve injury. FASEB J 2020; 34:5951-5966. [PMID: 32157739 DOI: 10.1096/fj.201901921r] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 02/17/2020] [Accepted: 02/27/2020] [Indexed: 12/14/2022]
Abstract
Neuron-immune interaction in the dorsal root ganglia (DRG) plays a pivotal role in the neuropathic pain development after nerve injury. Sigma-1 receptor (Sig-1R) is expressed by DRG neurons but its role in neuropathic pain is not fully understood. We investigated the effect of peripheral Sig-1R on neuroinflammation in the DRG after spared (sciatic) nerve injury (SNI) in mice. Nerve injury induced a decrease in NeuN staining along with the nuclear eccentricity and ATF3 expression in the injured DRG. Sig-1R was present in all DRG neurons examined, and after SNI this receptor translocated to the periphery of the soma and the vicinity of the nucleus, especially in injured ATF3 + neurons. In WT mice, injured DRG produced the chemokine CCL2, and this was followed by massive infiltration of macrophages/monocytes, which clustered mainly around sensory neurons with translocated Sig-1R, accompanied by robust IL-6 increase and mechanical allodynia. In contrast, Sig-1R knockout (Sig-1R-KO) mice showed reduced levels of CCL2, decreased macrophage/monocyte infiltration into DRG, and less IL-6 and neuropathic mechanical allodynia after SNI. Our findings point to an important role of peripheral Sig-1R in sensory neuron-macrophage/monocyte communication in the DRG after peripheral nerve injury; thus, these receptors may contribute to the neuropathic pain phenotype.
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Affiliation(s)
- Inmaculada Bravo-Caparrós
- Department of Pharmacology, School of Medicine, University of Granada, Granada, Spain
- Institute of Neuroscience, Biomedical Research Center, University of Granada, Granada, Spain
- Instituto de Investigación Biosanitaria IBS. GRANADA, Granada, Spain
| | - M Carmen Ruiz-Cantero
- Department of Pharmacology, School of Medicine, University of Granada, Granada, Spain
- Institute of Neuroscience, Biomedical Research Center, University of Granada, Granada, Spain
- Instituto de Investigación Biosanitaria IBS. GRANADA, Granada, Spain
| | - Gloria Perazzoli
- Instituto de Investigación Biosanitaria IBS. GRANADA, Granada, Spain
- Department of Human Anatomy and Embryology, School of Medicine, University of Granada, Granada, Spain
| | | | - José M Vela
- Drug Discovery and Preclinical Development, Esteve, Barcelona, Spain
| | - Mohamed F Hamed
- Department of Pathology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Josef M Penninger
- Institute of Molecular Biotechnology, Vienna, Austria
- Department of Medical Genetics, Life Science Institute, University of British Columbia, Vancouver, Canada
| | - José M Baeyens
- Department of Pharmacology, School of Medicine, University of Granada, Granada, Spain
- Institute of Neuroscience, Biomedical Research Center, University of Granada, Granada, Spain
- Instituto de Investigación Biosanitaria IBS. GRANADA, Granada, Spain
| | - Enrique J Cobos
- Department of Pharmacology, School of Medicine, University of Granada, Granada, Spain
- Institute of Neuroscience, Biomedical Research Center, University of Granada, Granada, Spain
- Instituto de Investigación Biosanitaria IBS. GRANADA, Granada, Spain
- Teófilo Hernando Institute for Drug Discovery, Madrid, Spain
| | - Francisco R Nieto
- Department of Pharmacology, School of Medicine, University of Granada, Granada, Spain
- Institute of Neuroscience, Biomedical Research Center, University of Granada, Granada, Spain
- Instituto de Investigación Biosanitaria IBS. GRANADA, Granada, Spain
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5
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Jiang H, Cui H, Wang T, Shimada SG, Sun R, Tan Z, Ma C, LaMotte RH. CCL2/CCR2 signaling elicits itch- and pain-like behavior in a murine model of allergic contact dermatitis. Brain Behav Immun 2019; 80:464-473. [PMID: 30981714 DOI: 10.1016/j.bbi.2019.04.026] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 03/14/2019] [Accepted: 04/10/2019] [Indexed: 12/16/2022] Open
Abstract
Spontaneous itch and pain are the most common symptoms in various skin diseases, including allergic contact dermatitis (ACD). The chemokine (C-C motif) ligand 2 (CCL2, also referred to as monocyte chemoattractant protein 1 (MCP-1)) and its receptor CCR2 are involved in the pathophysiology of ACD, but little is known of the role of CCL2/CCR2 for the itch- and pain-behaviors accompanying the murine model of this disorder, termed contact hypersensitivity (CHS). C57BL/6 mice previously sensitized to the hapten, squaric acid dibutyl ester, applied to the abdomen were subsequently challenged twice with the hapten delivered to either the cheek or to the hairy skin of the hind paw resulting in CHS at that site. By 24 h after the 2nd challenge to the hind paw CCL2 and CCR2 mRNA, protein, and signaling activity were upregulated in the dorsal root ganglion (DRG). Calcium imaging and whole-cell current-clamp recordings revealed that CCL2 directly acted on its neuronal receptor, CCR2 to activate a subset of small-diameter, nociceptive-like DRG neurons retrogradely labeled from the CHS site. Intradermal injection of CCL2 into the site of CHS on the cheek evoked site-directed itch- and pain-like behaviors which could be attenuated by prior delivery of an antagonist of CCR2. In contrast, CCL2 failed to elicit either type of behavior in control mice. Results are consistent with the hypothesis that CHS upregulates CCL2/CCR2 signaling in a subpopulation of cutaneous small diameter DRG neurons and that CCL2 can activate these neurons through neuronal CCR2 to elicit itch- and pain-behavior. Targeting the CCL2/CCR2 signaling might be beneficial for the treatment of the itch and pain sensations accompanying ACD in humans.
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Affiliation(s)
- Haowu Jiang
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510, USA; Department of 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 100005, China
| | - Huan Cui
- Department of 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 100005, China
| | - Tao Wang
- Department of 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 100005, China
| | - Steven G Shimada
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Rui Sun
- Department of Internal Medicine, Section of Digestive Diseases, Yale University, New Haven, CT 06510, USA
| | - Zhiyong Tan
- Department of Pharmacology and Toxicology and Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Chao Ma
- Department of 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 100005, China.
| | - Robert H LaMotte
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510, USA.
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Luo P, Shao J, Jiao Y, Yu W, Rong W. CC chemokine ligand 2 (CCL2) enhances TTX-sensitive sodium channel activity of primary afferent neurons in the complete Freud adjuvant-induced inflammatory pain model. Acta Biochim Biophys Sin (Shanghai) 2018; 50:1219-1226. [PMID: 30339176 DOI: 10.1093/abbs/gmy123] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Indexed: 11/14/2022] Open
Abstract
CC chemokine ligand 2 (CCL2) has been implicated in pathological pain, but the mechanism underlying the pronociceptive effect of CCL2 is not fully understood. Voltage-gated sodium (Nav) channels are important determinants of the excitability of sensory neurons. Hence we tested the hypothesis that CCL2 contributes to inflammatory pain via modulating Nav channel activity of primary afferent neurons. Chronic inflammatory pain was induced in rats by intraplantar injection of the complete Freud adjuvant (CFA) to one of the hind paws. Control rats received intraplantar injection of equal volume of saline. A significant increase of CCL2 mRNA and CCL2 receptor (CCR2) protein expression was detected in the ipsilateral dorsal root ganglion (DRG) in CFA-treated rats. Intraplantar injection of CCL2 protein in the control rats had minimal effect on the paw withdrawal threshold (PWT) in response to mechanical stimulation. However, in CFA-treated rats, intraplantar CCL2 led to an increase in pain responses. Patch-clamp recording of acutely dissociated DRG neurons revealed that CCL2 had minimum effect on the excitability of sensory neurons from control rats. However, CCL2 directly depolarized a large proportion of small to medium-sized sensory neurons from CFA-treated rats. In addition, CCL2 was found to enhance whole-cell TTX-sensitive sodium currents without significantly affecting the TTX-resistant sodium currents and the potassium currents. These results are in agreement with previous reports concerning the involvement of CCL2-CCR2 signaling in inflammatory hyperalgesia and further indicate that enhanced TTX-sensitive channel activity may partly underlie the pronociceptive effects of CCL2.
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Affiliation(s)
- Ping Luo
- Department of Anatomy and Physiology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Jiayun Shao
- Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Yingfu Jiao
- Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Weifeng Yu
- Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Weifang Rong
- Department of Anatomy and Physiology, Shanghai Jiaotong University School of Medicine, Shanghai, China
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7
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De Logu F, Nassini R, Materazzi S, Carvalho Gonçalves M, Nosi D, Rossi Degl'Innocenti D, Marone IM, Ferreira J, Li Puma S, Benemei S, Trevisan G, Souza Monteiro de Araújo D, Patacchini R, Bunnett NW, Geppetti P. Schwann cell TRPA1 mediates neuroinflammation that sustains macrophage-dependent neuropathic pain in mice. Nat Commun 2017; 8:1887. [PMID: 29192190 PMCID: PMC5709495 DOI: 10.1038/s41467-017-01739-2] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 10/12/2017] [Indexed: 11/28/2022] Open
Abstract
It is known that transient receptor potential ankyrin 1 (TRPA1) channels, expressed by nociceptors, contribute to neuropathic pain. Here we show that TRPA1 is also expressed in Schwann cells. We found that in mice with partial sciatic nerve ligation, TRPA1 silencing in nociceptors attenuated mechanical allodynia, without affecting macrophage infiltration and oxidative stress, whereas TRPA1 silencing in Schwann cells reduced both allodynia and neuroinflammation. Activation of Schwann cell TRPA1 evoked NADPH oxidase 1 (NOX1)-dependent H2O2 release, and silencing or blocking Schwann cell NOX1 attenuated nerve injury-induced macrophage infiltration, oxidative stress and allodynia. Furthermore, the NOX2-dependent oxidative burst, produced by macrophages recruited to the perineural space activated the TRPA1-NOX1 pathway in Schwann cells, but not TRPA1 in nociceptors. Schwann cell TRPA1 generates a spatially constrained gradient of oxidative stress, which maintains macrophage infiltration to the injured nerve, and sends paracrine signals to activate TRPA1 of ensheathed nociceptors to sustain mechanical allodynia.
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Affiliation(s)
- Francesco De Logu
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, 50139, Italy
| | - Romina Nassini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, 50139, Italy
| | - Serena Materazzi
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, 50139, Italy
| | - Muryel Carvalho Gonçalves
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, 50139, Italy
| | - Daniele Nosi
- Department of Experimental and Clinical Medicine, Section of Anatomy and Histology, University of Florence, Florence, 50139, Italy
| | - Duccio Rossi Degl'Innocenti
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, 50139, Italy
| | - Ilaria M Marone
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, 50139, Italy
| | - Juliano Ferreira
- Department of Pharmacology, Federal University of Santa Catarina, Florianópolis, 88040-500, Brazil
| | - Simone Li Puma
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, 50139, Italy
| | - Silvia Benemei
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, 50139, Italy
| | - Gabriela Trevisan
- Laboratory of Neuropsychopharmacology and Neurotoxicity, Graduate Program in Pharmacology, Federal University of Santa Maria (UFSM), Santa Maria, 97105-900, Brazil
| | - Daniel Souza Monteiro de Araújo
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, 50139, Italy
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Fluminense Federal University, Niterói, 20010-060, Brazil
| | | | - Nigel W Bunnett
- Departments of Surgery and Pharmacology, Columbia University, New York, NY, 10027, USA
| | - Pierangelo Geppetti
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, 50139, Italy.
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8
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Llorián-Salvador M, Pevida M, González-Rodríguez S, Lastra A, Fernández-García MT, Hidalgo A, Baamonde A, Menéndez L. Analgesic effects evoked by a CCR2 antagonist or an anti-CCL2 antibody in inflamed mice. Fundam Clin Pharmacol 2016; 30:235-47. [DOI: 10.1111/fcp.12182] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 12/22/2015] [Accepted: 01/25/2016] [Indexed: 12/22/2022]
Affiliation(s)
- María Llorián-Salvador
- Facultad de Medicina; Laboratorio de Farmacología; Instituto Universitario de Oncología del Principado de Asturias (IUOPA); Universidad de Oviedo; C/Julián Clavería 6 33006 Oviedo Spain
| | - Marta Pevida
- Facultad de Medicina; Laboratorio de Farmacología; Instituto Universitario de Oncología del Principado de Asturias (IUOPA); Universidad de Oviedo; C/Julián Clavería 6 33006 Oviedo Spain
| | - Sara González-Rodríguez
- Facultad de Medicina; Laboratorio de Farmacología; Instituto Universitario de Oncología del Principado de Asturias (IUOPA); Universidad de Oviedo; C/Julián Clavería 6 33006 Oviedo Spain
| | - Ana Lastra
- Facultad de Medicina; Laboratorio de Farmacología; Instituto Universitario de Oncología del Principado de Asturias (IUOPA); Universidad de Oviedo; C/Julián Clavería 6 33006 Oviedo Spain
| | - María-Teresa Fernández-García
- Unidad de Histopatología Molecular en Modelos Animales de Cáncer, IUOPA; Universidad de Oviedo; C/Julián Clavería 6 33006 Oviedo Spain
| | - Agustín Hidalgo
- Facultad de Medicina; Laboratorio de Farmacología; Instituto Universitario de Oncología del Principado de Asturias (IUOPA); Universidad de Oviedo; C/Julián Clavería 6 33006 Oviedo Spain
| | - Ana Baamonde
- Facultad de Medicina; Laboratorio de Farmacología; Instituto Universitario de Oncología del Principado de Asturias (IUOPA); Universidad de Oviedo; C/Julián Clavería 6 33006 Oviedo Spain
| | - Luis Menéndez
- Facultad de Medicina; Laboratorio de Farmacología; Instituto Universitario de Oncología del Principado de Asturias (IUOPA); Universidad de Oviedo; C/Julián Clavería 6 33006 Oviedo Spain
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9
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Solinski HJ, Gudermann T, Breit A. Pharmacology and signaling of MAS-related G protein-coupled receptors. Pharmacol Rev 2015; 66:570-97. [PMID: 24867890 DOI: 10.1124/pr.113.008425] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Signaling by heptahelical G protein-coupled receptors (GPCR) regulates many vital body functions. Consequently, dysfunction of GPCR signaling leads to pathologic states, and approximately 30% of all modern clinical drugs target GPCR. One decade ago, an entire new GPCR family was discovered, which was recently named MAS-related G protein-coupled receptors (MRGPR) by the HUGO Gene Nomenclature Committee. The MRGPR family consists of ∼40 members that are grouped into nine distinct subfamilies (MRGPRA to -H and -X) and are predominantly expressed in primary sensory neurons and mast cells. All members are formally still considered "orphan" by the Committee on Receptor Nomenclature and Drug Classification of the International Union of Basic and Clinical Pharmacology. However, several distinct peptides and amino acids are discussed as potential ligands, including β-alanine, angiotensin-(1-7), alamandine, GABA, cortistatin-14, and cleavage products of proenkephalin, pro-opiomelanocortin, prodynorphin, or proneuropeptide-FF-A. The full spectrum of biologic roles of all MRGPR is still ill-defined, but there is evidence pointing to a role of distinct MRGPR subtypes in nociception, pruritus, sleep, cell proliferation, circulation, and mast cell degranulation. This review article summarizes findings published in the last 10 years on the phylogenetic relationships, pharmacology, signaling, physiology, and agonist-promoted regulation of all MRGPR subfamilies. Furthermore, we highlight interactions between MRGPR and other hormonal systems, paying particular attention to receptor multimerization and morphine tolerance. Finally, we discuss the challenges the field faces presently and emphasize future directions of research.
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Affiliation(s)
- Hans Jürgen Solinski
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thomas Gudermann
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Andreas Breit
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
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Role for monocyte chemoattractant protein-1 in the induction of chronic muscle pain in the rat. Pain 2014; 155:1161-1167. [PMID: 24637038 DOI: 10.1016/j.pain.2014.03.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 02/27/2014] [Accepted: 03/06/2014] [Indexed: 01/25/2023]
Abstract
While raised levels of monocyte chemoattractant protein 1 (MCP-1) have been observed in patients with chronic muscle pain, direct evidence for its role as an algogen in skeletal muscle is still lacking. In the rat, MCP-1 induces a dose-dependent mechanical hyperalgesia lasting for up to 6weeks. Following recovery, rats exhibited a markedly prolonged hyperalgesia to an intramuscular injection of prostaglandin E2, hyperalgesic priming. Intrathecal pretreatment with isolectin B4 (IB4)-saporin, which selectively destroys IB4-positive (IB4+) nociceptors, markedly decreased MCP-1-induced hyperalgesia and prevented the subsequent development of priming. To evaluate the involvement of MCP-1 in stress-induced chronic pain we administered, intrathecally, antisense (AS) or mismatch oligodeoxynucleotides directed against CCR2 (the canonical receptor for MCP-1) mRNA, during the exposure to water-avoidance stress, a model of stress-induced persistent muscle pain. The AS treatment attenuated this hyperalgesia, whereas IB4-saporin abolished water-avoidance stress-induced muscle hyperalgesia and prevented stress-induced hyperalgesic priming. These results indicate that MCP-1 induces persistent muscle hyperalgesia and a state of latent chronic sensitization to other algogens, by action on its cognate receptor on IB4+ nociceptors. Because MCP-1 also contributes to stress-induced widespread chronic muscle pain, it should be considered as a player in chronic musculoskeletal pain syndromes.
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Contribution of chemokine CCL2/CCR2 signaling in the dorsal root ganglion and spinal cord to the maintenance of neuropathic pain in a rat model of lumbar disc herniation. THE JOURNAL OF PAIN 2014; 15:516-26. [PMID: 24462503 DOI: 10.1016/j.jpain.2014.01.492] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 01/11/2014] [Accepted: 01/16/2014] [Indexed: 12/20/2022]
Abstract
UNLABELLED Lumbar disc herniation (LDH) is a major cause of sciatica, but the underlying mechanisms are not well understood. Chemokine CCL2 has been implicated to play a vital role in the neuroinflammation and central sensitization after spinal nerve ligation. Here we investigated the expression and the role of CCL2 and its receptor CCR2 in LDH-induced pain. Implantation of autologous nucleus pulposus induced persistent pain hypersensitivity, associated with increased mRNA expression of CCL2 and CCR2 in the dorsal root ganglion and spinal cord. Interestingly, CCL2 was increased in neurons and CCR2 was mainly increased in macrophages in the dorsal root ganglion, whereas CCL2 and CCR2 were increased in astrocytes and neurons, respectively, in the spinal cord. Intrathecal injection of CCR2 antagonist RS504393 at 3 days or 10 days significantly attenuated nucleus pulposus-induced mechanical allodynia. The results suggest that CCL2/CCR2 in the dorsal root ganglion and spinal cord is involved in the maintenance of LDH-induced pain. Targeting CCL2/CCR2 signaling may be a potential treatment for chronic radicular neuropathic pain. PERSPECTIVE These results suggest that CCL2/CCR2 signaling in the dorsal root ganglion and spinal cord is involved in LDH-induced pain via distinct mechanisms. These findings provide evidence of the antinociceptive effect of CCR2 antagonist on radicular neuropathic pain.
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Yang Z, Luo W, Wang J, Tan Y, Fu R, Fang B. Chemokine ligand 2 in the trigeminal ganglion regulates pain induced by experimental tooth movement. Angle Orthod 2014; 84:730-6. [PMID: 24417496 DOI: 10.2319/090213-643.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE To test the hypothesis that the chemokine ligand 2/chemokine receptor 2 (CCL2/CCR2) signaling pathway plays an important role in pain induced by experimental tooth movement. MATERIALS AND METHODS Expression of CCL2/CCR2 in the trigeminal ganglion (TG) was determined by Western blotting 0 hours, 4 hours, 1 day, 3 days, 5 days, and 7 days after tooth movement. CCL2 localization and cell size distribution were revealed by immunohistochemistry. The effects of increasing force on CCL2 expression and behavioral changes were investigated. Furthermore, the effects of CCL2/CCR2 antagonists on these changes in pain behaviors were all evaluated. Exogenous CCL2 was injected into periodontal tissues and cultured TG neurons with different concentrations, and then the pain responses or c-fos expression were assessed. RESULTS Experimental tooth movement led to a statistically significant increase in CCL2/CCR2 expression from day 3 to day 7, especially in small to medium-sized TG neurons. It also triggered an increase in the time spent on directed face-grooming behaviors in a force magnitude-dependent and CCL2 dose-dependent manner. Pain induced by experimental tooth movement was effectively blocked by a CCR2 antagonist and by CCL2 neutralizing antibody. Also, exogenous CCL2 led to an increase in c-fos expression in cultured TG neurons, which was blocked by CCL2 neutralizing antibody. CONCLUSIONS The peripheral CCL2/CCR2 axis is modulated by experimental tooth movement and involved in the development of tooth movement pain.
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Affiliation(s)
- Zhi Yang
- a Research Scientist and Instructor, Department of Oral and Craniomaxillofacial Science, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, PR China
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Luo W, Fu R, Tan Y, Fang B, Yang Z. Chemokine CCL2 up-regulated in the medullary dorsal horn astrocytes contributes to nocifensive behaviors induced by experimental tooth movement. Eur J Oral Sci 2013; 122:27-35. [PMID: 24206110 DOI: 10.1111/eos.12099] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2013] [Indexed: 12/17/2022]
Affiliation(s)
- Wei Luo
- Department of Orthodontics; Shanghai Stomatological Disease Center; Shanghai China
| | - Runqing Fu
- Department of Oral & Cranio-Maxillofacial Science; Shanghai Ninth People's Hospital; School of Medicine; Shanghai Jiaotong University; Shanghai China
| | - Yu Tan
- Department of Oral & Cranio-Maxillofacial Science; Shanghai Ninth People's Hospital; School of Medicine; Shanghai Jiaotong University; Shanghai China
| | - Bing Fang
- Department of Oral & Cranio-Maxillofacial Science; Shanghai Ninth People's Hospital; School of Medicine; Shanghai Jiaotong University; Shanghai China
| | - Zhi Yang
- Department of Oral & Cranio-Maxillofacial Science; Shanghai Ninth People's Hospital; School of Medicine; Shanghai Jiaotong University; Shanghai China
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Solinski HJ, Petermann F, Rothe K, Boekhoff I, Gudermann T, Breit A. Human Mas-related G protein-coupled receptors-X1 induce chemokine receptor 2 expression in rat dorsal root ganglia neurons and release of chemokine ligand 2 from the human LAD-2 mast cell line. PLoS One 2013; 8:e58756. [PMID: 23505557 PMCID: PMC3591377 DOI: 10.1371/journal.pone.0058756] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 02/06/2013] [Indexed: 12/16/2022] Open
Abstract
Primate-specific Mas-related G protein-coupled receptors-X1 (MRGPR-X1) are highly enriched in dorsal root ganglia (DRG) neurons and induce acute pain. Herein, we analyzed effects of MRGPR-X1 on serum response factors (SRF) or nuclear factors of activated T cells (NFAT), which control expression of various markers of chronic pain. Using HEK293, DRG neuron-derived F11 cells and cultured rat DRG neurons recombinantly expressing human MRGPR-X1, we found activation of a SRF reporter gene construct and induction of the early growth response protein-1 via extracellular signal-regulated kinases-1/2 known to play a significant role in the development of inflammatory pain. Furthermore, we observed MRGPR-X1-induced up-regulation of the chemokine receptor 2 (CCR2) via NFAT, which is considered as a key event in the onset of neuropathic pain and, so far, has not yet been described for any endogenous neuropeptide. Up-regulation of CCR2 is often associated with increased release of its endogenous agonist chemokine ligand 2 (CCL2). We also found MRGPR-X1-promoted release of CCL2 in a human connective tissue mast cell line endogenously expressing MRGPR-X1. Thus, we provide first evidence to suggest that MRGPR-X1 induce expression of chronic pain markers in DRG neurons and propose a so far unidentified signaling circuit that enhances chemokine signaling by acting on two distinct yet functionally co-operating cell types. Given the important role of chemokine signaling in pain chronification, we propose that interruption of this signaling circuit might be a promising new strategy to alleviate chemokine-promoted pain.
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MESH Headings
- Animals
- Bradykinin/pharmacology
- Calcineurin/metabolism
- Calcium/metabolism
- Cell Line
- Chemokine CCL2/metabolism
- Early Growth Response Protein 1/genetics
- Early Growth Response Protein 1/metabolism
- Enzyme Activation/drug effects
- Ganglia, Spinal/metabolism
- Gene Expression Regulation/drug effects
- Genes, fos
- HEK293 Cells
- Humans
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Mast Cells/metabolism
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3/metabolism
- NFATC Transcription Factors/metabolism
- Peptide Fragments/pharmacology
- Rats
- Receptors, CCR2/genetics
- Receptors, CCR2/metabolism
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Sensory Receptor Cells/metabolism
- Serum Response Factor/metabolism
- Ternary Complex Factors/metabolism
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Affiliation(s)
- Hans Jürgen Solinski
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Franziska Petermann
- Department of Neurology, Klinikum rechts der Isar, Technical University Munich, Munich, Germany
| | - Kathrin Rothe
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Ingrid Boekhoff
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thomas Gudermann
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Andreas Breit
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, Munich, Germany
- * E-mail:
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Dorsal root ganglion compression as an animal model of sciatica and low back pain. Neurosci Bull 2012; 28:618-30. [PMID: 23054639 DOI: 10.1007/s12264-012-1276-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Accepted: 06/08/2012] [Indexed: 01/17/2023] Open
Abstract
As sciatica and low back pain are among the most common medical complaints, many studies have duplicated these conditions in animals. Chronic compression of the dorsal root ganglion (CCD) is one of these models. The surgery is simple: after exposing the L4/L5 intervertebral foramina, stainless steel rods are implanted unilaterally, one rod for each vertebra, to chronically compress the lumbar dorsal root ganglion (DRG). Then, CCD can be used to simulate the clinical conditions caused by stenosis, such as a laterally herniated disc or foraminal stenosis. As the intraforaminal implantation of a rod results in neuronal somal hyperexcitability and spontaneous action potentials associated with hyperalgesia, spontaneous pain, and mechanical allodynia, CCD provides an animal model that mimics radicular pain in humans. This review concerns the mechanisms of neuronal hyperexcitability, focusing on various patterns of spontaneous discharge including one possible pain signal for mechanical allodynia - evoked bursting. Also, new data regarding its significant property of maintaining peripheral input are also discussed. Investigations using this animal model will enhance our understanding of the neural mechanisms for low back pain and sciatica. Furthermore, the peripheral location of the DRG facilitates its use as a locus for controlling pain with minimal central effects, in the hope of ultimately uncovering analgesics that block neuropathic pain without influencing physiological pain.
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Kao DJ, Li AH, Chen JC, Luo RS, Chen YL, Lu JC, Wang HL. CC chemokine ligand 2 upregulates the current density and expression of TRPV1 channels and Nav1.8 sodium channels in dorsal root ganglion neurons. J Neuroinflammation 2012; 9:189. [PMID: 22870919 PMCID: PMC3458897 DOI: 10.1186/1742-2094-9-189] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 07/02/2012] [Indexed: 12/22/2022] Open
Abstract
Background Inflammation or nerve injury-induced upregulation and release of chemokine CC chemokine ligand 2 (CCL2) within the dorsal root ganglion (DRG) is believed to enhance the activity of DRG nociceptive neurons and cause hyperalgesia. Transient receptor potential vanilloid receptor 1 (TRPV1) and tetrodotoxin (TTX)-resistant Nav1.8 sodium channels play an essential role in regulating the excitability and pain transmission of DRG nociceptive neurons. We therefore tested the hypothesis that CCL2 causes peripheral sensitization of nociceptive DRG neurons by upregulating the function and expression of TRPV1 and Nav1.8 channels. Methods DRG neuronal culture was prepared from 3-week-old Sprague–Dawley rats and incubated with various concentrations of CCL2 for 24 to 36 hours. Whole-cell voltage-clamp recordings were performed to record TRPV1 agonist capsaicin-evoked inward currents or TTX-insensitive Na+ currents from control or CCL2-treated small DRG sensory neurons. The CCL2 effect on the mRNA expression of TRPV1 or Nav1.8 was measured by real-time quantitative RT-PCR assay. Results Pretreatment of CCL2 for 24 to 36 hours dose-dependently (EC50 value = 0.6 ± 0.05 nM) increased the density of capsaicin-induced currents in small putative DRG nociceptive neurons. TRPV1 mRNA expression was greatly upregulated in DRG neurons preincubated with 5 nM CCL2. Pretreating small DRG sensory neurons with CCL2 also increased the density of TTX-resistant Na+ currents with a concentration-dependent manner (EC50 value = 0.7 ± 0.06 nM). The Nav1.8 mRNA level was significantly increased in DRG neurons pretreated with CCL2. In contrast, CCL2 preincubation failed to affect the mRNA level of TTX-resistant Nav1.9. In the presence of the specific phosphatidylinositol-3 kinase (PI3K) inhibitor LY294002 or Akt inhibitor IV, CCL2 pretreatment failed to increase the current density of capsaicin-evoked inward currents or TTX-insensitive Na+ currents and the mRNA level of TRPV1 or Nav1.8. Conclusions Our results showed that CCL2 increased the function and mRNA level of TRPV1 channels and Nav1.8 sodium channels in small DRG sensory neurons via activating the PI3K/Akt signaling pathway. These findings suggest that following tissue inflammation or peripheral nerve injury, upregulation and release of CCL2 within the DRG could facilitate pain transmission mediated by nociceptive DRG neurons and could induce hyperalgesia by upregulating the expression and function of TRPV1 and Nav1.8 channels in DRG nociceptive neurons.
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Affiliation(s)
- Der-Jang Kao
- Department of Physiology and Pharmacology, Chang Gung University School of Medicine, Kwei-San, Tao-Yuan 333, Taiwan
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Richards N, Batty T, Dilley A. CCL2 has similar excitatory effects to TNF-α in a subgroup of inflamed C-fiber axons. J Neurophysiol 2011; 106:2838-48. [PMID: 21865436 PMCID: PMC3234089 DOI: 10.1152/jn.00183.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Peripheral nerve inflammation can cause neuronal excitability changes that have been implicated in the pathogenesis of chronic pain. Although the neuroimmune interactions that lead to such physiological changes are unclear, in vitro studies suggest that the chemokine CCL2 may be involved. This in vivo study examines the effects of CCL2 on untreated and inflamed neurons and compares its effects with those of TNF-α. Extracellular recordings were performed in the anesthetized rat on isolated neurons with C-fiber axons. On untreated neurons, CCL2, as well as TNF-α, had negligible effects. Following neuritis, both cytokines transiently caused the firing of action potentials in 27–30% of neurons, which were either silent or had background (ongoing) activity. The neurons with ongoing activity, which responded to either cytokine, had significantly slower baseline firing rates {median = 3.0 spikes/min [interquartile range (IQR) 3.0]} compared with the nonresponders [median = 24.4 spikes/min (IQR 24.6); P < 0.001]. In an additional group, 26–27% of neurons, which were sensitized due to repeated noxious mechanical stimulation of the periphery, also responded to the effects of both cytokines. Neither cytokine caused axons to become mechanically sensitive. Immunohistochemistry confirmed that the cognate CCL2 receptor, CCR2, is mainly expressed on glia and is therefore not likely to be an axonal target for CCL2 following inflammation. In contrast, the cognate TNF-α receptor (TNFR), TNFR1, was present on untreated and inflamed neurons. In summary, CCL2 can excite inflamed C-fiber neurons with similar effects to TNF-α, although the underlying mechanisms may be different. The modulatory effects of both cytokines are limited to a subgroup of neurons, which may be subtly inflamed.
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Affiliation(s)
- Natalie Richards
- Division of Clinical and Laboratory Investigation, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, UK
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Foster R, Jung J, Farooq A, McClung C, Ripsch MS, Fitzgerald MP, White FA. Sciatic nerve injury induces functional pro-nociceptive chemokine receptors in bladder-associated primary afferent neurons in the rat. Neuroscience 2011; 183:230-7. [PMID: 21458542 PMCID: PMC3219924 DOI: 10.1016/j.neuroscience.2011.03.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 03/18/2011] [Accepted: 03/19/2011] [Indexed: 02/06/2023]
Abstract
Visceral sensory afferents during disease or following injury often produce vague, diffuse body sensations, and pain referred to somatic targets. Alternatively, injury due to trauma or disease of somatic nerve targets can also lead to referred pain in visceral targets via a somatovisceral reflex. Both phenomenons are thought to be due to convergence of visceral and somatic afferents within the spinal cord. To investigate a potential peripheral influence for referred pain in visceral targets following somatic nerve injury, we examined whether a sciatic nerve injury known to produce hindpaw tactile hyperalgesia alters the frequency of micturition and the sensitivity of bladder-associated sensory neurons to pro-nociceptive chemokines. Adult female Sprague-Dawley rats received injections of cholera toxin B subunit conjugated to 555 into urinary bladder wall to retrogradely label visceral primary afferent neurons. After 7 days, the right sciatic nerve of these animals was subjected to a lysophosphatidylcholine (LPC)-induced focal demyelination injury. Pre- and post-injury tactile sensitivity in the hind paw and micturition frequency were assayed. Animals were allowed to survive for 14-28 days. Lumbosacral and lumbar dorsal root ganglia (DRG) ipsilateral to the nerve injury were acutely dissociated from sham and nerve injured animals. Bladder wall-associated sensory neurons identified via the retrograde marker were assayed for fluxes in intracellular calcium following administration of pro-nociceptive chemokines. The assayed chemokines included monocyte chemoattractant protein-1 (MCP1/CCL2) and stromal cell derived factor-1 alpha (SDF1/CXCL12). LPC nerve injured animals exhibited tactile hyperalgesia and increased micturition frequency for at least 28 days. Focal demyelination of the sciatic nerve also increased the number of injured L₄L₅ and non-injured L₆-S₂ bladder-associated sensory neurons that responded to MCP1 and SDF1 when compared with sensory neurons derived from uninjured naïve and sham-injured control animals. Taken together, these data suggest that some visceral hypersensitivity states may have a somatic origin. More importantly, nociceptive somatovisceral sensation may be mediated by upregulation of chemokine signaling in visceral sensory neurons.
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Affiliation(s)
- R Foster
- Department of Urology, Loyola University Health System, Maywood, IL, USA
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