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Mandlem VKK, Rivera A, Khan Z, Quazi SH, Deba F. TLR4 induced TRPM2 mediated neuropathic pain. Front Pharmacol 2024; 15:1472771. [PMID: 39329114 PMCID: PMC11424904 DOI: 10.3389/fphar.2024.1472771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2024] [Accepted: 09/02/2024] [Indexed: 09/28/2024] Open
Abstract
Ion channels play an important role in mediating pain through signal transduction, regulation, and control of responses, particularly in neuropathic pain. Transient receptor potential channel superfamily plays an important role in cation permeability and cellular signaling. Transient receptor potential channel Melastatin 2 (TRPM2) subfamily regulates Ca2+ concentration in response to various chemicals and signals from the surrounding environment. TRPM2 has a role in several physiological functions such as cellular osmosis, temperature sensing, cellular proliferation, as well as the manifestation of many disease processes such as pain process, cancer, apoptosis, endothelial dysfunction, angiogenesis, renal and lung fibrosis, and cerebral ischemic stroke. Toll-like Receptor 4 (TLR4) is a critical initiator of the immune response to inflammatory stimuli, particularly those triggered by Lipopolysaccharide (LPS). It activates downstream pathways leading to the production of oxidative molecules and inflammatory cytokines, which are modulated by basal and store-operated calcium ion signaling. The cytokine production and release cause an imbalance of antioxidant enzymes and redox potential in the Endoplasmic Reticulum and mitochondria due to oxidative stress, which results from TLR-4 activation and consequently induces the production of inflammatory cytokines in neuronal cells, exacerbating the pain process. Very few studies have reported the role of TRPM2 and its association with Toll-like receptors in the context of neuropathic pain. However, the molecular mechanism underlying the interaction between TRPM2 and TLR-4 and the quantum of impact in acute and chronic neuropathic pain remains unclear. Understanding the link between TLR-4 and TRPM2 will provide more insights into pain regulation mechanisms for the development of new therapeutic molecules to address neuropathic pain.
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Affiliation(s)
- Venkata Kiran Kumar Mandlem
- Departmental of Pharmaceutical Sciences and Health Outcomes, The Ben and Maytee Fisch College of Pharmacy, University of Texas at Tyler, Tyler, TX, United States
| | - Ana Rivera
- Departmental of Pharmaceutical Sciences and Health Outcomes, The Ben and Maytee Fisch College of Pharmacy, University of Texas at Tyler, Tyler, TX, United States
| | - Zaina Khan
- Departmental of Pharmaceutical Sciences and Health Outcomes, The Ben and Maytee Fisch College of Pharmacy, University of Texas at Tyler, Tyler, TX, United States
- Departmental of Neuroscience, University of Texas at Dallas, Richardson, TX, United States
| | - Sohel H Quazi
- Departmental of Pharmaceutical Sciences and Health Outcomes, The Ben and Maytee Fisch College of Pharmacy, University of Texas at Tyler, Tyler, TX, United States
- Department of Biology, Division of Natural and Computation Sciences, Texas College, Tyler, TX, United States
| | - Farah Deba
- Departmental of Pharmaceutical Sciences and Health Outcomes, The Ben and Maytee Fisch College of Pharmacy, University of Texas at Tyler, Tyler, TX, United States
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2
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Zhou Y, Sun G, Li C, Bai X. Grb2 Expression in Acute Spinal Cord Injury After Methylprednisolone Intrathecal Injection in Rats. Int J Spine Surg 2023; 17:678-683. [PMID: 37884335 PMCID: PMC10623675 DOI: 10.14444/8527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023] Open
Abstract
OBJECTIVE This study aims to investigate the effect of methylprednisolone (MP) intrathecal injection on a rat model of acute spinal cord injury (ASCI). METHODS Allen's frame was used to establish a rat model of ASCI. MP and normal saline were intrathecally injected to Sprague-Dawley rats at 0, 3, 6, 8, 12, and 24 hours after ASCI, and injured spinal cord tissues were sterilely extracted after 24 hours of treatment. Isobaric tags for relative and absolute quantitation (iTRAQ) were coupled with 2-dimensional liquid chromatography tandem mass spectrometry to separate and identify differentially expressed proteins. RESULTS The expression of growth factor receptor-bound protein 2 (Grb2) was downregulated in the MP groups at 0 hours (iTRAQ ratio = 0.996), 3 hours (iTRAQ ratio = 0.737), 8 hours (iTRAQ ratio = 0.763), and 24 hours (iTRAQ ratio = 0.908) after injury compared with that in the control groups. No significant difference in Grb2 expression was observed between the control groups at 6 and 12 hours after ASCI. CONCLUSIONS Standardized MP intrathecal injection after ASCI treatment reduces Grb2 activation in a rat ASCI model. Further studies should determine whether or not the same effect can be observed in human ASCIs.
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Affiliation(s)
- Yijun Zhou
- The First People's Hospital of Changde, Changde Hospital Affiliated to Xiangya Medical College of Central South University, Hunan, People's Republic of China
| | - Guanwen Sun
- The First People's Hospital of Changde, Changde Hospital Affiliated to Xiangya Medical College of Central South University, Hunan, People's Republic of China
| | - Changhong Li
- The First People's Hospital of Changde, Changde Hospital Affiliated to Xiangya Medical College of Central South University, Hunan, People's Republic of China
| | - Xiaoan Bai
- The First People's Hospital of Changde, Changde Hospital Affiliated to Xiangya Medical College of Central South University, Hunan, People's Republic of China
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3
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Kim HW, Yong H, Shea GKH. Blood-spinal cord barrier disruption in degenerative cervical myelopathy. Fluids Barriers CNS 2023; 20:68. [PMID: 37743487 PMCID: PMC10519090 DOI: 10.1186/s12987-023-00463-y] [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: 07/07/2023] [Accepted: 08/12/2023] [Indexed: 09/26/2023] Open
Abstract
Degenerative cervical myelopathy (DCM) is the most prevalent cause of spinal cord dysfunction in the aging population. Significant neurological deficits may result from a delayed diagnosis as well as inadequate neurological recovery following surgical decompression. Here, we review the pathophysiology of DCM with an emphasis on how blood-spinal cord barrier (BSCB) disruption is a critical yet neglected pathological feature affecting prognosis. In patients suffering from DCM, compromise of the BSCB is evidenced by elevated cerebrospinal fluid (CSF) to serum protein ratios and abnormal contrast-enhancement upon magnetic resonance imaging (MRI). In animal model correlates, there is histological evidence of increased extravasation of tissue dyes and serum contents, and pathological changes to the neurovascular unit. BSCB dysfunction is the likely culprit for ischemia-reperfusion injury following surgical decompression, which can result in devastating neurological sequelae. As there are currently no therapeutic approaches specifically targeting BSCB reconstitution, we conclude the review by discussing potential interventions harnessed for this purpose.
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Affiliation(s)
- Hyun Woo Kim
- Department of Orthopaedics and Traumatology, LKS Faulty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Hu Yong
- Department of Orthopaedics and Traumatology, LKS Faulty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Graham Ka Hon Shea
- Department of Orthopaedics and Traumatology, LKS Faulty of Medicine, The University of Hong Kong, Hong Kong, China.
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4
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Weng HR, Taing K, Chen L, Penney A. EZH2 Methyltransferase Regulates Neuroinflammation and Neuropathic Pain. Cells 2023; 12:1058. [PMID: 37048131 PMCID: PMC10093242 DOI: 10.3390/cells12071058] [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: 02/28/2023] [Revised: 03/24/2023] [Accepted: 03/29/2023] [Indexed: 04/03/2023] Open
Abstract
Recent studies by us and others have shown that enhancer of zeste homolog-2 (EZH2), a histone methyltransferase, in glial cells regulates the genesis of neuropathic pain by modulating the production of proinflammatory cytokines and chemokines. In this review, we summarize recent advances in this research area. EZH2 is a subunit of polycomb repressive complex 2 (PRC2), which primarily serves as a histone methyltransferase to catalyze methylation of histone 3 on lysine 27 (H3K27), ultimately resulting in transcriptional repression. Animals with neuropathic pain exhibit increased EZH2 activity and neuroinflammation of the injured nerve, spinal cord, and anterior cingulate cortex. Inhibition of EZH2 with DZNep or GSK-126 ameliorates neuroinflammation and neuropathic pain. EZH2 protein expression increases upon activation of Toll-like receptor 4 and calcitonin gene-related peptide receptors, downregulation of miR-124-3p and miR-378 microRNAs, or upregulation of Lncenc1 and MALAT1 long noncoding RNAs. Genes suppressed by EZH2 include suppressor of cytokine signaling 3 (SOCS3), nuclear factor (erythroid-derived 2)-like-2 factor (NrF2), miR-29b-3p, miR-146a-5p, and brain-specific angiogenesis inhibitor 1 (BAI1). Pro-inflammatory mediators facilitate neuronal activation along pain-signaling pathways by sensitizing nociceptors in the periphery, as well as enhancing excitatory synaptic activities and suppressing inhibitory synaptic activities in the CNS. These studies collectively reveal that EZH2 is implicated in signaling pathways known to be key players in the process of neuroinflammation and genesis of neuropathic pain. Therefore, targeting the EZH2 signaling pathway may open a new avenue to mitigate neuroinflammation and neuropathic pain.
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Affiliation(s)
- Han-Rong Weng
- Department of Basic Sciences, California Northstate University College of Medicine, Elk Grove, CA 95757, USA
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5
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Chen Y, Chen H, Li XC, Mi WL, Chu YX, Wang YQ, Mao-Ying QL. Neuronal toll like receptor 9 contributes to complete Freund’s adjuvant-induced inflammatory pain in mice. Front Mol Neurosci 2022; 15:1008203. [PMID: 36277489 PMCID: PMC9582929 DOI: 10.3389/fnmol.2022.1008203] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 09/12/2022] [Indexed: 11/13/2022] Open
Abstract
Toll like receptor 9 (TLR9) is a critical sensor for danger-associated molecular patterns (DAMPs) and a crucial marker of non-sterile/sterile inflammation among all TLRs. However, the significance of TLR9 in inflammatory pain remains unclear. Here, we subcutaneously injected Complete Freund’s adjuvant (CFA) into the plantar surface of the hind paw, to established a mouse model of inflammatory pain, and we examined expression and distribution of TLR9 in this model. There was a significant increase of TLR9 mRNA and reduction of mechanical paw withdrawal threshold in mice intraplantar injected with CFA. By contrast, mechanical paw withdrawal threshold significantly increased in mice treated with TLR9 antagonist ODN2088. Furthermore, TLR9 is found predominantly distributed in the neurons by immunofluorescence experiment. Accordingly, neuronal TLR9 downregulation in the spinal cord prevented CFA-induced persistent hyperalgesia. Overall, these findings indicate that neuronal TLR9 in the spinal cord is closely related to CFA-induced inflammatory pain. It provides a potential treatment option for CFA-induced inflammatory pain by applying TLR9 antagonist.
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Affiliation(s)
- Yu Chen
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine, Fudan University, Shanghai, China
| | - Hui Chen
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine, Fudan University, Shanghai, China
| | - Xiao-Chen Li
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine, Fudan University, Shanghai, China
| | - Wen-Li Mi
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine, Fudan University, Shanghai, China
- Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function, Fudan University, Shanghai, China
| | - Yu-Xia Chu
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine, Fudan University, Shanghai, China
- Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function, Fudan University, Shanghai, China
| | - Yan-Qing Wang
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine, Fudan University, Shanghai, China
- Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function, Fudan University, Shanghai, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Qi-Liang Mao-Ying
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine, Fudan University, Shanghai, China
- Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function, Fudan University, Shanghai, China
- *Correspondence: Qi-Liang Mao-Ying,
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Pottorf TS, Rotterman TM, McCallum WM, Haley-Johnson ZA, Alvarez FJ. The Role of Microglia in Neuroinflammation of the Spinal Cord after Peripheral Nerve Injury. Cells 2022; 11:cells11132083. [PMID: 35805167 PMCID: PMC9265514 DOI: 10.3390/cells11132083] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 06/26/2022] [Accepted: 06/27/2022] [Indexed: 12/12/2022] Open
Abstract
Peripheral nerve injuries induce a pronounced immune reaction within the spinal cord, largely governed by microglia activation in both the dorsal and ventral horns. The mechanisms of activation and response of microglia are diverse depending on the location within the spinal cord, type, severity, and proximity of injury, as well as the age and species of the organism. Thanks to recent advancements in neuro-immune research techniques, such as single-cell transcriptomics, novel genetic mouse models, and live imaging, a vast amount of literature has come to light regarding the mechanisms of microglial activation and alluding to the function of microgliosis around injured motoneurons and sensory afferents. Herein, we provide a comparative analysis of the dorsal and ventral horns in relation to mechanisms of microglia activation (CSF1, DAP12, CCR2, Fractalkine signaling, Toll-like receptors, and purinergic signaling), and functionality in neuroprotection, degeneration, regeneration, synaptic plasticity, and spinal circuit reorganization following peripheral nerve injury. This review aims to shed new light on unsettled controversies regarding the diversity of spinal microglial-neuronal interactions following injury.
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Affiliation(s)
- Tana S. Pottorf
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
| | - Travis M. Rotterman
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30318, USA;
| | - William M. McCallum
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
| | - Zoë A. Haley-Johnson
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
| | - Francisco J. Alvarez
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
- Correspondence:
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7
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Yan M, Song Z, Kou H, Shang G, Shang C, Chen X, Ji Y, Bao D, Cheng T, Li J, Lv X, Liu H, Chen S. New Progress in Basic Research of Macrophages in the Pathogenesis and Treatment of Low Back Pain. Front Cell Dev Biol 2022; 10:866857. [PMID: 35669508 PMCID: PMC9163565 DOI: 10.3389/fcell.2022.866857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 04/05/2022] [Indexed: 11/13/2022] Open
Abstract
Low back pain (LBP) is quite common in clinical practice, which can lead to long-term bed rest or even disability. It is a worldwide health problem remains to be solved. LBP can be induced or exacerbated by abnormal structure and function of spinal tissue such as intervertebral disc (IVD), dorsal root ganglion (DRG) and muscle; IVD degeneration (IVDD) is considered as the most important among all the pathogenic factors. Inflammation, immune response, mechanical load, and hypoxia etc., can induce LBP by affecting the spinal tissue, among which inflammation and immune response are the key link. Inflammation and immune response play a double-edged sword role in LBP. As the main phagocytic cells in the body, macrophages are closely related to body homeostasis and various diseases. Recent studies have shown that macrophages are the only inflammatory cells that can penetrate the closed nucleus pulposus, expressed in various structures of the IVD, and the number is positively correlated with the degree of IVDD. Moreover, macrophages play a phagocytosis role or regulate the metabolism of DRG and muscle tissues through neuro-immune mechanism, while the imbalance of macrophages polarization will lead to more inflammatory factors to chemotaxis and aggregation, forming an "inflammatory waterfall" effect similar to "positive feedback," which greatly aggravates LBP. Regulation of macrophages migration and polarization, inhibition of inflammation and continuous activation of immune response by molecular biological technology can markedly improve the inflammatory microenvironment, and thus effectively prevent and treat LBP. Studies on macrophages and LBP were mainly focused in the last 3-5 years, attracting more and more scholars' attention. This paper summarizes the new research progress of macrophages in the pathogenesis and treatment of LBP, aiming to provide an important clinical prevention and treatment strategy for LBP.
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Affiliation(s)
- Miaoheng Yan
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Zongmian Song
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Hongwei Kou
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Guowei Shang
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | | | - Xiangrong Chen
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yanhui Ji
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Deming Bao
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Tian Cheng
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Jinfeng Li
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xiao Lv
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hongjian Liu
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Songfeng Chen
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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8
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Aghamiri SH, Komlakh K, Ghaffari M. The crosstalk among TLR2, TLR4 and pathogenic pathways; a treasure trove for treatment of diabetic neuropathy. Inflammopharmacology 2022; 30:51-60. [PMID: 35020096 DOI: 10.1007/s10787-021-00919-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 12/19/2021] [Indexed: 11/25/2022]
Abstract
Diabetes is correlated with organ failures as a consequence of microvascular diabetic complications, including neuropathy, nephropathy, and retinopathy. These difficulties come with serious clinical manifestations and high medical costs. Diabetic neuropathy (DN) is one of the most prevalent diabetes complications, affecting at least 50% of diabetic patients with long disease duration. DN has serious effects on patients' life since it interferes with their daily physical activities and causes psychological comorbidities. There are some potential risk factors for the development of neuropathic injuries. It has been shown that inflammatory mechanisms play a pivotal role in the progression of DN. Among inflammatory players, TLR2 and TLR4 have gained immense importance because of their ability in recognizing distinct molecular patterns of invading pathogens and also damage-associated molecular patterns (DAMPs) providing inflammatory context for the progression of a wide array of disorders. We, therefore, sought to explore the possible role of TLR2 and TLR4 in DN pathogenesis and if whether manipulating TLRs is likely to be successful in fighting off DN.
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Affiliation(s)
- Seyed Hossein Aghamiri
- Department of Neurology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Khalil Komlakh
- Department of Neurosurgery, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Mehran Ghaffari
- Department of Neurology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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9
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Chan WH, Huang NC, Lin YW, Lin FY, Tsai CS, Yeh CC. Intrathecal IGF2 siRNA injection provides long-lasting anti-allodynic effect in a spared nerve injury rat model of neuropathic pain. PLoS One 2021; 16:e0260887. [PMID: 34855889 PMCID: PMC8638935 DOI: 10.1371/journal.pone.0260887] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 11/18/2021] [Indexed: 01/12/2023] Open
Abstract
Previous studies have shown an increase of insulin-like growth factor-2 (IGF2) in animal models of neuropathic pain. We aimed to examine the hypothesis that reducing the expression of IGF2 using intrathecal IGF2 small-interfering RNA (siRNA) would attenuate the development of neuropathic pain in rats after spared nerve injury (SNI). Male Wistar rats were divided into three groups: sham-operated group, in which surgery was performed to cut the muscles without injuring the nerves; SNI group, in which SNI surgery was performed to sever the nerves; and SNI + siRNA IGF2 group, in which SNI surgery was performed, and IGF2-siRNA was administered intrathecally 1 day after SNI. The rats were assessed for mechanical allodynia and cold allodynia 1 day before surgery (baseline), and at 2, 4, 6, 8, and 10 days after siRNA treatment. The rat spinal cord was collected for quantitative polymerase chain reaction and western blot analysis. Compared with the SNI group, rats that received IGF2 siRNA showed a significantly increased SNI-induced paw-withdrawal threshold to metal filament stimulation from Day 4 to Day 10 after SNI surgery. IGF2 siRNA significantly decreased the response duration from the acetone test from Day 2 to Day 10 following SNI surgery. SNI increased IGF2 mRNA expression on Day 2 and increased IGF2 protein expression on Day 8 and Day 10 in the spinal cord of the SNI rats. However, the above-mentioned effects of IGF2 mRNA and protein expression were significantly inhibited in the SNI + IGF2 siRNA group. We demonstrated that intrathecal administration of IGF2 siRNA provided significant inhibition of SNI-induced neuropathic pain via inhibition of IGF2 expression in the spinal cord. The analgesic effect lasted for 10 days. Further exploration of intrathecal IGF2 siRNA administration as a potential therapeutic strategy for neuropathic pain is warranted.
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Affiliation(s)
- Wei-Hung Chan
- Department of Anesthesiology, National Defense Medical Center, Taipei, Taiwan
- Department of Anesthesiology, Tri-Service General Hospital, Taipei, Taiwan
| | - Nian-Cih Huang
- Department of Anesthesiology, National Defense Medical Center, Taipei, Taiwan
- Department of Anesthesiology, Tri-Service General Hospital, Taipei, Taiwan
| | - Yi-Wen Lin
- Institute of Oral Biology, National Yang-Ming Chiao-Tung University, Hsinchu, Taiwan
| | - Feng-Yen Lin
- Department of Internal Medicine and Taipei Heart Institute, Taipei Medical University, Taipei, Taiwan
- Division of Cardiology, Taipei Medical University Hospital, Taipei, Taiwan
| | - Chien-Sung Tsai
- Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
- Department and Graduate Institute of Pharmacology, National Defense Medical Center, Taipei, Taiwan
| | - Chun-Chang Yeh
- Department of Anesthesiology, National Defense Medical Center, Taipei, Taiwan
- Department of Anesthesiology, Tri-Service General Hospital, Taipei, Taiwan
- * E-mail:
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10
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Ferreira-Gomes J, Garcia MM, Nascimento D, Almeida L, Quesada E, Castro-Lopes JM, Pascual D, Goicoechea C, Neto FL. TLR4 Antagonism Reduces Movement-Induced Nociception and ATF-3 Expression in Experimental Osteoarthritis. J Pain Res 2021; 14:2615-2627. [PMID: 34466029 PMCID: PMC8403032 DOI: 10.2147/jpr.s317877] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/29/2021] [Indexed: 01/13/2023] Open
Abstract
Introduction Toll-like receptor 4 (TLR4) is a pattern recognition receptor involved in the detection of pathogen-associated molecular patterns (PAMPs), but also a "danger-sensing" receptor that recognizes host-derived endogenous molecules called damage-associated molecular patterns (DAMPs). The involvement of TLR4 in rheumatic diseases is becoming evident, as well as its potential role as a target for therapeutic intervention. Moreover, increasing evidence also suggests that TLR4 is implicated in chronic pain states. Thus, in this study, we evaluated whether a systemic administration of a synthetic antagonist of TLR4 (TLR4-A1) could decrease nociception and cartilage degradation in experimental osteoarthritis (OA). Furthermore, as the activation transcription factor (ATF)-3 serves as a negative regulator for TLR4-stimulated inflammatory response, we also evaluated the effect of TLR4 inhibition on ATF-3 expression in primary afferent neurons at the dorsal root ganglia (DRG). Methods OA was induced in adult male Wistar rats through an intra-articular injection of 2 mg of sodium mono-iodoacetate (MIA) into the left knee. From days 14 to 28 after OA induction, animals received an intraperitoneal injection of either TLR4-A1 (10 mg/kg) or vehicle. Movement- and loading-induced nociception was evaluated in all animals, by the Knee-Bend and CatWalk tests, before and at several time-points after TLR4-A1/vehicle administration. Immunofluorescence for TLR4 and ATF-3 was performed in L3-L5 DRG. Knee joints were processed for histopathological evaluation. Results Administration of TLR4-A1 markedly reduced movement-induced nociception in OA animals, particularly in the Knee-Bend test. Moreover, the increase of ATF-3 expression observed in DRG of OA animals was significantly reduced by TLR4-A1. However, no effect was observed in cartilage loss nor in the neuronal cytoplasmic expression of TLR4 upon antagonist administration. Conclusion The TLR4 antagonist administration possibly interrupts the TLR4 signalling cascade, thus decreasing the neurotoxic environment at the joint, which leads to a reduction in ATF-3 expression and in nociception associated with experimental OA.
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Affiliation(s)
- Joana Ferreira-Gomes
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - Miguel M Garcia
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Unidad Asociada I+D+i Instituto de Química Médica (IQM) CSIC-URJC, Madrid, Spain.,High Performance Experimental Pharmacology research group, Universidad Rey Juan Carlos (PHARMAKOM), Alcorcón, Spain.,Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo multidisciplinar de investigación y tratamiento del dolor (i+DOL), Alcorcón, Spain
| | - Diana Nascimento
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - Lígia Almeida
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - Ernesto Quesada
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Unidad Asociada I+D+i Instituto de Química Médica (IQM) CSIC-URJC, Madrid, Spain.,Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo multidisciplinar de investigación y tratamiento del dolor (i+DOL), Alcorcón, Spain
| | - José Manuel Castro-Lopes
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - David Pascual
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Unidad Asociada I+D+i Instituto de Química Médica (IQM) CSIC-URJC, Madrid, Spain.,High Performance Experimental Pharmacology research group, Universidad Rey Juan Carlos (PHARMAKOM), Alcorcón, Spain.,Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo multidisciplinar de investigación y tratamiento del dolor (i+DOL), Alcorcón, Spain
| | - Carlos Goicoechea
- Area of Pharmacology, Nutrition and Bromatology, Department of Basic Health Sciences, Universidad Rey Juan Carlos, Unidad Asociada I+D+i Instituto de Química Médica (IQM) CSIC-URJC, Madrid, Spain.,High Performance Experimental Pharmacology research group, Universidad Rey Juan Carlos (PHARMAKOM), Alcorcón, Spain.,Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo multidisciplinar de investigación y tratamiento del dolor (i+DOL), Alcorcón, Spain
| | - Fani Lourença Neto
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Departamento de Biomedicina, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
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11
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Koc B, Kizildag S, Hosgorler F, Gumus H, Kandis S, Ates M, Uysal N. Magnesium Citrate Increases Pain Threshold and Reduces TLR4 Concentration in the Brain. Biol Trace Elem Res 2021; 199:1954-1966. [PMID: 32989649 DOI: 10.1007/s12011-020-02384-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 09/09/2020] [Indexed: 10/23/2022]
Abstract
Magnesium is being investigated in various clinical conditions and has shown to be effective in some chronic pain models. However, it is not clear if oral magnesium use affects pain perception in acute pain. TLR4's (toll-like receptor) role in pain perception has emerged through its role in immune pathways and ion channels. The aim of this study is to investigate the effect of a single oral dose of magnesium citrate on pain conduction and whether with magnesium, the expression of TLR4 changes in the acute phase. Following a single dose of 66-mg/kg magnesium citrate administration to male Balb-c mice, pain perception (via hot-plate test), motor conduction (via electrophysiological recording, forelimb grip strength, rotarod and open-field tests), and emotional state (via elevated plus maze and forced swim test) were evaluated. In behavioral experiments, the control group was compared with applied magnesium for three different time groups (4, 8, 24 h). TLR4 expression was measured in four groups: control, magnesium (Mg), hot plate (HP), and Mg + HP. Hot plate latency was prolonged in the magnesium group (p < 0.0001) and electrophysiological recordings (p < 0.001) and forelimb grip strength measurement (p < 0.001) determined motor latency. Compared with the untreated hot plate group, TLR4 levels was lower in the brain (p = 0.023) and higher in the sciatic nerve (p = 0.001) in the magnesium-treated hot plate group. Consequently, the study indicated a single dose of magnesium citrate appeared to cause weakening in the transmission and perception of nociceptive pain. TLR4 may act as a regulator in magnesium's effects on pain perception.
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Affiliation(s)
- Basar Koc
- Department of Physiology, School of Medicine, Dokuz Eylül University, Izmir, Turkey
| | - Servet Kizildag
- College of Vocational School of Health Services, School of Medicine, Dokuz Eylül University, Izmir, Turkey
| | - Ferda Hosgorler
- Department of Physiology, School of Medicine, Dokuz Eylül University, Izmir, Turkey
| | - Hikmet Gumus
- Department of Sports Medicine, School of Medicine, Dokuz Eylül University, Izmir, Turkey
| | - Sevim Kandis
- Department of Physiology, School of Medicine, Dokuz Eylül University, Izmir, Turkey
| | - Mehmet Ates
- College of Vocational School of Health Services, School of Medicine, Dokuz Eylül University, Izmir, Turkey
| | - Nazan Uysal
- Department of Physiology, School of Medicine, Dokuz Eylül University, Izmir, Turkey.
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12
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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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13
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Moretti IF, Lerario AM, Trombetta-Lima M, Sola PR, da Silva Soares R, Oba-Shinjo SM, Marie SKN. Late p65 nuclear translocation in glioblastoma cells indicates non-canonical TLR4 signaling and activation of DNA repair genes. Sci Rep 2021; 11:1333. [PMID: 33446690 PMCID: PMC7809124 DOI: 10.1038/s41598-020-79356-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 12/01/2020] [Indexed: 02/08/2023] Open
Abstract
Glioblastoma (GBM) is the most aggressive brain primary malignancy. Toll-like receptor 4 (TLR4) has a dual role in cell fate, promoting cell survival or death depending on the context. Here, we analyzed TLR4 expression in different grades of astrocytoma, and observed increased expression in tumors, mainly in GBM, compared to non-neoplastic brain tissue. TLR4 role was investigated in U87MG, a GBM mesenchymal subtype cell line, upon LPS stimulation. p65 nuclear translocation was observed in late phase, suggesting TLR4-non-canonical pathway activation. In fact, components of ripoptosome and inflammasome cascades were upregulated and they were significantly correlated in GBMs of the TCGA-RNASeq dataset. Moreover, an increased apoptotic rate was observed when the GBM-derived U87MG cells were co-treated with LPS and Temozolomide (TMZ) in comparison to TMZ alone. Increased TLR4 immunostaining was detected in nuclei of U87MG cells 12 h after LPS treatment, concomitant to activation of DNA repair genes. Time-dependent increased RAD51, FEN1 and UNG expression levels were confirmed after LPS stimulation, which may contribute to tumor cell fitness. Moreover, the combined treatment with the RAD51 inhibitor, Amuvatinib in combination with, TMZ after LPS stimulation reduced tumor cell viability more than with each treatment alone. In conclusion, our results suggest that stimulation of TLR4 combined with pharmacological inhibition of the DNA repair pathway may be an alternative treatment for GBM patients.
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Affiliation(s)
- Isabele F Moretti
- Laboratory of Molecular and Cellular Biology (LIM15), Department of Neurology, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, São Paulo, SP, Brazil.
| | - Antonio M Lerario
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI, USA
| | - Marina Trombetta-Lima
- Laboratory of Molecular and Cellular Biology (LIM15), Department of Neurology, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, São Paulo, SP, Brazil
| | - Paula R Sola
- Laboratory of Molecular and Cellular Biology (LIM15), Department of Neurology, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, São Paulo, SP, Brazil
| | - Roseli da Silva Soares
- Laboratory of Molecular and Cellular Biology (LIM15), Department of Neurology, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, São Paulo, SP, Brazil
| | - Sueli M Oba-Shinjo
- Laboratory of Molecular and Cellular Biology (LIM15), Department of Neurology, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, São Paulo, SP, Brazil
| | - Suely K N Marie
- Laboratory of Molecular and Cellular Biology (LIM15), Department of Neurology, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, São Paulo, SP, Brazil
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14
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Rinne M, Mätlik K, Ahonen T, Vedovi F, Zappia G, Moreira VM, Yli-Kauhaluoma J, Leino S, Salminen O, Kalso E, Airavaara M, Xhaard H. Mitoxantrone, pixantrone and mitoxantrone (2-hydroxyethyl)piperazine are toll-like receptor 4 antagonists, inhibit NF-κB activation, and decrease TNF-alpha secretion in primary microglia. Eur J Pharm Sci 2020; 154:105493. [PMID: 32730846 DOI: 10.1016/j.ejps.2020.105493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 07/22/2020] [Accepted: 07/27/2020] [Indexed: 10/23/2022]
Abstract
Toll-like receptor 4 (TLR4) recognizes various endogenous and microbial ligands and is an essential part in the innate immune system. TLR4 signaling initiates transcription factor NF-κB and production of proinflammatory cytokines. TLR4 contributes to the development or progression of various diseases including stroke, neuropathic pain, multiple sclerosis, rheumatoid arthritis and cancer, and better therapeutics are currently sought for these conditions. In this study, a library of 140 000 compounds was virtually screened and a resulting hit-list of 1000 compounds was tested using a cellular reporter system. The topoisomerase II inhibitor mitoxantrone and its analogues pixantrone and mitoxantrone (2-hydroxyethyl)piperazine were identified as inhibitors of TLR4 and NF-κB activation. Mitoxantrone was shown to bind directly to the TLR4, and pixantrone and mitoxantrone (2-hydroxyethyl)piperazine were shown to inhibit the production of proinflammatory cytokines such as tumor necrosis factor alpha (TNFα) in primary microglia. The inhibitory effect on NF-κB activation or on TNFα production was not mediated through cytotoxity at ≤ 1 µM concentration for pixantrone and mitoxantrone (2-hydroxyethyl)piperazine treated cells, as assessed by ATP counts. This study thus identifies a new mechanism of action for mitoxantrone, pixantrone, and mitoxantrone (2-hydroxyethyl)piperazine through the TLR4.
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Affiliation(s)
- Maiju Rinne
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland
| | - Kert Mätlik
- Institute of Biotechnology, HiLIFE, University of Helsinki, FI-00014 Helsinki, Finland; Department of Pharmacology, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Tiina Ahonen
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland
| | - Fabio Vedovi
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland; Department of Biomolecular Sciences, University Urbino Carlo Bo, P.zza Rinascimento, 6 61029 Urbino (PU), Italy
| | - Giovanni Zappia
- Department of Biomolecular Sciences, University Urbino Carlo Bo, P.zza Rinascimento, 6 61029 Urbino (PU), Italy
| | - Vânia M Moreira
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland; Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, G4 0RE Glasgow, U.K; Laboratory of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Coimbra, 3004-548 Coimbra, Portugal; Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Jari Yli-Kauhaluoma
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland
| | - Sakari Leino
- Drug Research Program, Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland
| | - Outi Salminen
- Drug Research Program, Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland
| | - Eija Kalso
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, FI-00014 Helsinki, Finland; Department of Anaesthesiology, Intensive Care and Pain Medicine, University of Helsinki and Helsinki University Hospital. FI-00029 HUS, Finland
| | - Mikko Airavaara
- Institute of Biotechnology, HiLIFE, University of Helsinki, FI-00014 Helsinki, Finland
| | - Henri Xhaard
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland.
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15
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Hijma HJ, Moss LM, Gal P, Ziagkos D, de Kam ML, Moerland M, Groeneveld GJ. Challenging the challenge: A randomized controlled trial evaluating the inflammatory response and pain perception of healthy volunteers after single-dose LPS administration, as a potential model for inflammatory pain in early-phase drug development. Brain Behav Immun 2020; 88:515-528. [PMID: 32305572 DOI: 10.1016/j.bbi.2020.04.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 04/10/2020] [Accepted: 04/13/2020] [Indexed: 10/24/2022] Open
Abstract
BACKGROUND AND AIMS Following an infection, cytokines not only regulate the acute immune response, but also contribute to symptoms such as inflammatory hyperalgesia. We aimed to characterize the acute inflammatory response induced by a human endotoxemia model, and its effect on pain perception using evoked pain tests in two different dose levels. We also attempted to determine whether combining a human endotoxemia challenge with measurement of pain thresholds in healthy subjects could serve as a model to study drug effects on inflammatory pain. METHODS AND RESULTS This was a placebo-controlled, randomized, cross-over study in 24 healthy males. Twelve subjects were administered a bolus of 1 ng/kg LPS intravenously, and twelve 2 ng/kg LPS. Before days of placebo/LPS administration, subjects completed a full study day without study drug administration, but with identical pain threshold testing. Blood sampling and evoked pain tests (electrical burst and -stair, heat, pressure, and cold pressor test) were performed pre-dose and at frequent intervals up to 10hr post-dose. Data were analysed with a repeated-measures ANCOVA. For both dose levels, LPS induced an evident acute inflammatory response, but did not significantly affect any of the pain modalities. In a post-hoc analysis, lowering of pain thresholds was observed in the first 3 h after dosing, corresponding with the peak of the acute inflammatory response around 1-3 h post-dose. CONCLUSION Mild acute systemic inflammation, as induced by 1 ng/kg and 2 ng/kg LPS intravenous administration, did not significantly change pain thresholds in this study. The endotoxemia model in combination with evoked pain tests is not suitable to study acute inflammatory hyperalgesia in healthy males.
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Affiliation(s)
- H J Hijma
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands; Leiden University Medical Centre, 2333 ZA Leiden, The Netherlands.
| | - L M Moss
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands; Leiden University Medical Centre, 2333 ZA Leiden, The Netherlands.
| | - P Gal
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands; Leiden University Medical Centre, 2333 ZA Leiden, The Netherlands.
| | - D Ziagkos
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands.
| | - M L de Kam
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands.
| | - M Moerland
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands; Leiden University Medical Centre, 2333 ZA Leiden, The Netherlands.
| | - G J Groeneveld
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands; Leiden University Medical Centre, 2333 ZA Leiden, The Netherlands.
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16
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Paclitaxel Induces Upregulation of Transient Receptor Potential Vanilloid 1 Expression in the Rat Spinal Cord. Int J Mol Sci 2020; 21:ijms21124341. [PMID: 32570786 PMCID: PMC7352737 DOI: 10.3390/ijms21124341] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 06/11/2020] [Indexed: 02/07/2023] Open
Abstract
Painful peripheral neuropathy is a common adverse effect of paclitaxel (PTX) treatment. To analyze the contribution of transient receptor potential vanilloid 1 (TRPV1) in the development of PTX-induced mechanical allodynia/hyperalgesia and thermal hyperalgesia, TRPV1 expression in the rat spinal cord was analyzed after intraperitoneal administration of 2 and 4 mg/kg PTX. PTX treatment increased the expression of TRPV1 protein in the spinal cord. Immunohistochemistry showed that PTX (4 mg/kg) treatment increased TRPV1 protein expression in the superficial layers of the spinal dorsal horn 14 days after treatment. Behavioral assessment using the paw withdrawal response showed that PTX-induced mechanical allodynia/hyperalgesia and thermal hyperalgesia after 14 days was significantly inhibited by oral or intrathecal administration of the TRPV1 antagonist AMG9810. We found that intrathecal administration of small interfering RNA (siRNA) to knock down TRPV1 protein expression in the spinal cord significantly decreased PTX-induced mechanical allodynia/hyperalgesia and thermal hyperalgesia. Together, these results demonstrate that TRPV1 receptor expression in spinal cord contributes, at least in part, to the development of PTX-induced painful peripheral neuropathy. TRPV1 receptor antagonists may be useful in the prevention and treatment of PTX-induced peripheral neuropathic pain.
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17
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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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18
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DeMarco GJ, Nunamaker EA. A Review of the Effects of Pain and Analgesia on Immune System Function and Inflammation: Relevance for Preclinical Studies. Comp Med 2019; 69:520-534. [PMID: 31896389 PMCID: PMC6935697 DOI: 10.30802/aalas-cm-19-000041] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
One of the most significant challenges facing investigators, laboratory animal veterinarians, and IACUCs, is how to balance appropriate analgesic use, animal welfare, and analgesic impact on experimental results. This is particularly true for in vivo studies on immune system function and inflammatory disease. Often times the effects of analgesic drugs on a particular immune function or model are incomplete or don't exist. Further complicating the picture is evidence of the very tight integration and bidirectional functionality between the immune system and branches of the nervous system involved in nociception and pain. These relationships have advanced the concept of understanding pain as a protective neuroimmune function and recognizing pathologic pain as a neuroimmune disease. This review strives to summarize extant literature on the effects of pain and analgesia on immune system function and inflammation in the context of preclinical in vivo studies. The authors hope this work will help to guide selection of analgesics for preclinical studies of inflammatory disease and immune system function.
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Key Words
- cb,endocannabinoid receptor
- cd,crohn disease
- cfa, complete freund adjuvant
- cgrp,calcitonin gene-related peptide
- cox,cyclooxygenase
- ctl, cytotoxic t-lymphocytes
- damp,damage-associated molecular pattern molecules
- drg,dorsal root ganglion
- dss, dextran sodium sulphate
- ecs,endocannabinoid system
- ibd, inflammatory bowel disease
- ifa,incomplete freund adjuvant
- las, local anesthetics
- pamp,pathogen-associated molecular pattern molecules
- pge2, prostaglandin e2
- p2y, atp purine receptor y
- p2x, atp purine receptor x
- tnbs, 2,4,6-trinitrobenzene sulphonic acid
- trp, transient receptor potential ion channels
- trpv, transient receptor potential vanilloid
- tg,trigeminal ganglion
- uc,ulcerative colitis
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Affiliation(s)
- George J DeMarco
- Department of Animal Medicine, University of Massachusetts Medical School, Worcester, Massachusetts;,
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19
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Hermann JK, Capadona JR. Understanding the Role of Innate Immunity in the Response to Intracortical Microelectrodes. Crit Rev Biomed Eng 2019; 46:341-367. [PMID: 30806249 DOI: 10.1615/critrevbiomedeng.2018027166] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intracortical microelectrodes exhibit enormous potential for researching the nervous system, steering assistive devices and functional electrode stimulation systems for severely paralyzed individuals, and augmenting the brain with computing power. Unfortunately, intracortical microelectrodes often fail to consistently record signals over clinically useful periods. Biological mechanisms, such as the foreign body response to intracortical microelectrodes and self-perpetuating neuroinflammatory cascades, contribute to the inconsistencies and decline in recording performance. Unfortunately, few studies have directly correlated microelectrode performance with the neuroinflammatory response to the implanted devices. However, of those select studies that have, the role of the innate immune system remains among the most likely links capable of corroborating the results of different studies, across laboratories. Therefore, the overall goal of this review is to highlight the role of innate immunity signaling in the foreign body response to intracortical microelectrodes and hypothesize as to appropriate strategies that may become the most relevant in enabling brain-dwelling electrodes of any geometry, or location, for a range of clinical applications.
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Affiliation(s)
- John K Hermann
- Department of Biomedical Engineering, Case Western Reserve University, 2071 Martin Luther King Jr. Drive, Wickenden Bldg, Cleveland, OH 44106; Advanced Platform Technology Center, Rehabilitation Research and Development, Louis Stokes Cleveland VA Medical Center, 10701 East Blvd. Mail Stop 151 AW/APT, Cleveland, OH 44106-1702
| | - Jeffrey R Capadona
- Department of Biomedical Engineering, Case Western Reserve University, 2071 Martin Luther King Jr. Drive, Wickenden Bldg, Cleveland, OH 44106; Advanced Platform Technology Center, Rehabilitation Research and Development, Louis Stokes Cleveland VA Medical Center, 10701 East Blvd. Mail Stop 151 AW/APT, Cleveland, OH 44106-1702
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20
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Elzinga S, Murdock BJ, Guo K, Hayes JM, Tabbey MA, Hur J, Feldman EL. Toll-like receptors and inflammation in metabolic neuropathy; a role in early versus late disease? Exp Neurol 2019; 320:112967. [PMID: 31145897 DOI: 10.1016/j.expneurol.2019.112967] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 05/24/2019] [Accepted: 05/26/2019] [Indexed: 02/07/2023]
Abstract
Neuropathy is a common, morbid complication of the metabolic syndrome, prediabetes, and diabetes. Recent studies have indicated a potential role for the immune system in the development of neuropathy. In particular, toll-like receptors (TLR) 2 and 4 have been linked to metabolic dysfunction, and blocking TLR4 is proposed as a treatment for neuropathic pain. In the current study, we investigated the role of the immune system, particularly TLRs 2 and 4, in the pathogenesis and progression of neuropathy. Sural or sciatic nerve gene expression arrays from humans and murine neuropathy models of prediabetes and diabetes were first analyzed to identify differentially expressed TLR2- and TLR4-associated genes within the KEGG (Kyoto Encyclopedia of Genes and Genomes) database. We observed that genes associated with TLRs 2 and 4, particularly lipopolysaccharide binding protein (LPB) and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit beta (PIK3CB), were dysregulated across species and across multiple murine models of prediabetic and diabetic neuropathy. To further understand the role of these pathways in vivo, TLR 2 and 4 global knockout mice placed on a 60% high fat diet (HFD-TLR2/4-/-) were compared with wild type (WT) mice on a high fat diet (HFD-WT) and WT controls on a standard diet (CON). Mice then underwent metabolic, neuropathic, and immunological phenotyping at two time points to assess the impact of TLR signaling on neuropathy and immunity during metabolic dysfunction over time. We found that HFD-TLR2/4-/- and HFD-WT mice weighed more than CON mice but did not have increased fasting blood glucose levels. Despite normal blood glucose levels, HFD-TLR2/4-/- mice eventually developed neuropathy at the later time point (28 wks of age) but were somewhat protected from neuropathy at the early time point (16 wks of age) as measured by shorter hind paw withdraw latencies. This is in contrast to HFD-WT mice which developed neuropathy within 11 wks of being placed on a high fat diet and were neuropathic by all measures at both the early and late time points. Finally, we immunophenotyped all three mouse groups at the later time point and found differences in the number of peripheral blood Ly6C-myeloid cells as well as F4/80+ expression. These results indicate that TLR signaling influences early development of neuropathy in sensory neurons, potentially via immune modulation and recruitment.
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Affiliation(s)
- S Elzinga
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - B J Murdock
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - K Guo
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - J M Hayes
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - M A Tabbey
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - J Hur
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - E L Feldman
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA.
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21
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de la Peña JBI, Song JJ, Campbell ZT. RNA control in pain: Blame it on the messenger. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1546. [PMID: 31090211 DOI: 10.1002/wrna.1546] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 04/17/2019] [Accepted: 04/22/2019] [Indexed: 12/12/2022]
Abstract
mRNA function is meticulously controlled. We provide an overview of the integral role that posttranscriptional controls play in the perception of painful stimuli by sensory neurons. These specialized cells, termed nociceptors, precisely regulate mRNA polarity, translation, and stability. A growing body of evidence has revealed that targeted disruption of mRNAs and RNA-binding proteins robustly diminishes pain-associated behaviors. We propose that the use of multiple independent regulatory paradigms facilitates robust temporal and spatial precision of protein expression in response to a range of pain-promoting stimuli. This article is categorized under: RNA in Disease and Development > RNA in Disease Translation > Translation Regulation RNA Turnover and Surveillance > Regulation of RNA Stability.
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Affiliation(s)
- June Bryan I de la Peña
- Department of Biological Sciences and the Center for Advanced Pain Studies, University of Texas, Dallas, Richardson, Texas
| | - Jane J Song
- Department of Biological Sciences and the Center for Advanced Pain Studies, University of Texas, Dallas, Richardson, Texas
| | - Zachary T Campbell
- Department of Biological Sciences and the Center for Advanced Pain Studies, University of Texas, Dallas, Richardson, Texas
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22
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Yang FR, Chen J, Yi H, Peng LY, Hu XL, Guo QL. MicroRNA-7a ameliorates neuropathic pain in a rat model of spinal nerve ligation via the neurofilament light polypeptide-dependent signal transducer and activator of transcription signaling pathway. Mol Pain 2019; 15:1744806919842464. [PMID: 30987515 PMCID: PMC6537231 DOI: 10.1177/1744806919842464] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Neuropathic pain is a type of chronic pain induced by either central or
peripheral nerve injury. MicroRNAs have been recently linked to many diseases,
including neuropathic pain. However, the role of miR-7a in neuropathic pain
still remains elusive. Thus, we aim to investigate the effects of miR-7a on
neuropathic pain based on the spinal nerve ligation rat model. After
establishment of spinal nerve ligation rat models, rats were infected with
adeno-associated virus-neurofilament light polypeptide, adeno-associated
virus-miR-7a or treated with metformin. The paw withdrawal threshold and paw
withdrawal latency were assessed afterward, and the expression of miR-7a and
neurofilament light polypeptide as well as their interaction was determined.
Subsequently, miR-7a was overexpressed or silenced in dorsal root ganglion cells
to investigate the role of miR-7a in neuropathic pain. Furthermore, the
regulatory effect of neurofilament light polypeptide on neuropathic pain was
detected using plasmid overexpressing neurofilament light polypeptide. Spinal
nerve ligation rat model exhibited upregulation of neurofilament light
polypeptide but downregulation of miR-7a. In addition, neurofilament light
polypeptide accumulation or miR-7a inhibition decreased paw withdrawal threshold
and paw withdrawal latency. Then, neurofilament light polypeptide accumulation
or miR-7a inhibition was observed to increase the phosphorylation level of
signal transducer and activator of transcription. miR-7a was found to directly
target neurofilament light polypeptide and downregulate neurofilament light
polypeptide. In addition, inhibiting the signal transducer and activator of
transcription signaling pathway was also revealed to increase paw withdrawal
threshold and paw withdrawal latency. Collectively, our study demonstrated that
miR-7a ameliorated neuropathic pain via blocking the signal transducer and
activator of transcription signaling pathway by repressing neurofilament light
polypeptide. These findings, if taken further, can be of important clinical
significance in treating patients with neuropathic pain.
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Affiliation(s)
- Feng-Rui Yang
- 1 Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, P.R. China.,2 Department of Anesthesiology, the First Affiliated Hospital of University of South China, Hengyang, P.R. China
| | - Ji Chen
- 3 Department of Endocrinology, the First Affiliated Hospital of University of South China, Hengyang, P.R. China
| | - Han Yi
- 2 Department of Anesthesiology, the First Affiliated Hospital of University of South China, Hengyang, P.R. China
| | - Liang-Yu Peng
- 2 Department of Anesthesiology, the First Affiliated Hospital of University of South China, Hengyang, P.R. China
| | - Xiao-Ling Hu
- 2 Department of Anesthesiology, the First Affiliated Hospital of University of South China, Hengyang, P.R. China
| | - Qu-Lian Guo
- 1 Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, P.R. China
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23
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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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24
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Yuan L, Li T, Wan Y, Liu Y, Zhou X, Liu C. Pregabalin on Hdac2 and Inpp5f levels in rats with CCI-induced neuropathic pain. Exp Ther Med 2019; 17:1300-1305. [PMID: 30680006 PMCID: PMC6327674 DOI: 10.3892/etm.2018.7037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 11/19/2018] [Indexed: 01/27/2023] Open
Abstract
Hdac2/Inpp5f on the therapeutic effect of pregabalin on neuropathic pain in chronic constriction injury (CCI) rats was investigated. A total of 90 healthy SD rats were selected and divided into the treatment group, the model control group and the normal control group with 30 rats in each group. Rats in the treatment and model control groups were used to construct CCI model. The control group was treated with sham surgery. The model control group was not treated after surgery. The treatment group was treated with pregabalin on the 8th day after operation. Behavioral experiments were performed to measure mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL). The expression of inflammatory cytokines TNFα and IL-1β was detected by ELISA kit and expression of Hdac2 and Inpp5f mRNA was detected by RT-qPCR. Before treatment, compared with the normal control group, MWT and TWL values of the treatment and model control groups were significantly decreased (P<0.05). At different time-points after treatment, MWT and TWL were higher in the treatment group than in the model control group and were lower than in the normal control group. At 21 days after operation, the levels of TNFα and IL-1β in the model control and treatment groups were higher than those in the normal control group (P<0.05). The expression level of Hdac2 was higher in the treatment group than in the normal control group (P<0.05). The expression level of Inpp5f mRNA in the treatment and normal control groups was significantly higher than that in the model control group (P<0.05), but the expression level of Inpp5f mRNA in the treatment group was lower than that in the normal control group (P<0.05). Therefore, pregabalin can effectively relieve neuropathic pain in CCI rats, and its efficacy is related to Hdac2 and Inpp5f. Our study provides reference for clinical treatment of neuropathic pain induced by CCI.
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Affiliation(s)
- Lili Yuan
- Department of Anesthesiology, The Fifth Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
| | - Tao Li
- Department of Anesthesiology, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130033, P.R. China
| | - Yingchun Wan
- Department of Endocrinology, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130033, P.R. China
| | - Yanwei Liu
- Department of General Surgery, Taihe Hospital, Shiyan, Hubei 442000, P.R. China
| | - Xianjin Zhou
- Department of Anesthesiology, First Maternity and Infant Hospital Affiliated to Tongji University, Shanghai 200040, P.R. China
| | - Caihua Liu
- Department of Anesthesiology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430014, P.R. China
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25
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Activation of GABA B Receptor Suppresses Diabetic Neuropathic Pain through Toll-Like Receptor 4 Signaling Pathway in the Spinal Dorsal Horn. Mediators Inflamm 2018; 2018:6016272. [PMID: 30647535 PMCID: PMC6311757 DOI: 10.1155/2018/6016272] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Accepted: 09/26/2018] [Indexed: 11/30/2022] Open
Abstract
Diabetic neuropathic pain (DNP) is a prevalent complication in diabetes patients. Neuronal inflammation and activation of Toll-like receptor 4 (TLR4) are involved in the occurrence of DNP. However, the underlying mechanisms remain unclear. Downregulation of gamma-aminobutyric acid B (GABAB) receptor contributes to the DNP. GABAB receptor interacts with NF-κB, a downstream signaling factor of TLR4, in a neuropathic pain induced by chemotherapy. In this study, we determined the role of TLR4/Myd88/NF-κB signaling pathways coupled to GABAB receptors in the generation of DNP. Intrathecal injection of baclofen (GABAB receptor agonist), LPS-RS ultrapure (TLR4 antagonist), MIP (MyD88 antagonist), or SN50 (NF-κB inhibitor) significantly increased paw withdrawal threshold (PWT) and paw withdrawal thermal latency (PWTL) in DNP rats, while intrathecal injection of saclofen (GABAB receptor blocker) decreased PWT and PWTL in DNP rats. The expression of TLR4, Myd88, NF-κBp65, and their downstream components IL-1 and TNF-α was significantly higher in the spinal cord tissue in DNP rats compared to control rats. Following inhibition of TLR4, Myd88, and NF-κB, the expression of IL-1 and TNF-α decreased. Activation of GABAB receptors downregulated the expression of TLR4, Myd88, NF-κBp65, IL-1, and TNF-α. Blockade of GABAB receptors significantly upregulated expression of TLR4, Myd88, NF-κBp65, IL-1, and TNF-α. These data suggest that activation of the TLR4/Myd88/NF-κB signaling pathway is involved in the occurrence of DNP in rats. Activation of GABAB receptor in the spinal cord may suppress the TLR4/Myd88/NF-κB signaling pathway and alleviate the DNP.
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26
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Zhang ZJ, Guo JS, Li SS, Wu XB, Cao DL, Jiang BC, Jing PB, Bai XQ, Li CH, Wu ZH, Lu Y, Gao YJ. TLR8 and its endogenous ligand miR-21 contribute to neuropathic pain in murine DRG. J Exp Med 2018; 215:3019-3037. [PMID: 30455267 PMCID: PMC6279408 DOI: 10.1084/jem.20180800] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 09/10/2018] [Accepted: 10/17/2018] [Indexed: 01/20/2023] Open
Abstract
TLRs are known to be essential for innate and adaptive immunity. Zhang et al. show the involvement of TLR8 and its endogenous ligand miR-21 in neuropathic pain via inducing ERK-dependent proinflammatory mediators’ production and neuronal hyperexcitability in the DRG. Toll-like receptors (TLRs) are nucleic acid–sensing receptors and have been implicated in mediating pain and itch. Here we report that Tlr8−/− mice show normal itch behaviors, but have defects in neuropathic pain induced by spinal nerve ligation (SNL) in mice. SNL increased TLR8 expression in small-diameter IB4+ DRG neurons. Inhibition of TLR8 in the DRG attenuated SNL-induced pain hypersensitivity. Conversely, intrathecal or intradermal injection of TLR8 agonist, VTX-2337, induced TLR8-dependent pain hypersensitivity. Mechanistically, TLR8, localizing in the endosomes and lysosomes, mediated ERK activation, inflammatory mediators’ production, and neuronal hyperexcitability after SNL. Notably, miR-21 was increased in DRG neurons after SNL. Intrathecal injection of miR-21 showed the similar effects as VTX-2337 and inhibition of miR-21 in the DRG attenuated neuropathic pain. The present study reveals a previously unknown role of TLR8 in the maintenance of neuropathic pain, suggesting that miR-21–TLR8 signaling may be potential new targets for drug development against this type of chronic pain.
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Affiliation(s)
- Zhi-Jun Zhang
- Pain Research Laboratory, Institute of Nautical Medicine, Nantong University, Jiangsu, China.,Department of Human Anatomy, School of Medicine, Nantong University, Jiangsu, China
| | - Jian-Shuang Guo
- Pain Research Laboratory, Institute of Nautical Medicine, Nantong University, Jiangsu, China
| | - Si-Si Li
- Pain Research Laboratory, Institute of Nautical Medicine, Nantong University, Jiangsu, China
| | - Xiao-Bo Wu
- Pain Research Laboratory, Institute of Nautical Medicine, Nantong University, Jiangsu, China
| | - De-Li Cao
- Pain Research Laboratory, Institute of Nautical Medicine, Nantong University, Jiangsu, China
| | - Bao-Chun Jiang
- Pain Research Laboratory, Institute of Nautical Medicine, Nantong University, Jiangsu, China
| | - Peng-Bo Jing
- Pain Research Laboratory, Institute of Nautical Medicine, Nantong University, Jiangsu, China
| | - Xue-Qiang Bai
- Department of Human Anatomy, School of Medicine, Nantong University, Jiangsu, China
| | - Chun-Hua Li
- Pain Research Laboratory, Institute of Nautical Medicine, Nantong University, Jiangsu, China
| | - Zi-Han Wu
- Pain Research Laboratory, Institute of Nautical Medicine, Nantong University, Jiangsu, China.,Department of Human Anatomy, School of Medicine, Nantong University, Jiangsu, China
| | - Ying Lu
- Pain Research Laboratory, Institute of Nautical Medicine, Nantong University, Jiangsu, China.,Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Jiangsu, China
| | - Yong-Jing Gao
- Pain Research Laboratory, Institute of Nautical Medicine, Nantong University, Jiangsu, China .,Co-innovation Center of Neuroregeneration, Nantong University, Jiangsu, China
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27
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Liu Y, Zhang Y, Pan R, Chen M, Wang X, Kong E, Yu W, Sun Y, Wu F. Lentiviral‑mediated inducible silencing of TLR4 attenuates neuropathic pain in a rat model of chronic constriction injury. Mol Med Rep 2018; 18:5545-5551. [PMID: 30365084 PMCID: PMC6236283 DOI: 10.3892/mmr.2018.9560] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 08/10/2018] [Indexed: 12/12/2022] Open
Abstract
An increasing body of evidence has indicated that spinal microglial Toll-like receptor 4 (TLR4) may serve a significant role in the development and maintenance of neuropathic pain (NP). In the present study, experiments were conducted to evaluate the contribution of a tetracycline inducible lentiviral-mediated delivery system for the expression of TLR4 small interfering (si)RNA to NP in rats with chronic constriction injury (CCI). Behavioral tests, including paw withdrawal latency and paw withdrawal threshold, and biochemical analysis of the spinal cord, including western blotting, reverse transcription-quantitative polymerase chain reaction and ELISA, were conducted following CCI to the sciatic nerve. Intrathecal administration of LvOn-si-TLR4 with doxycycline (Dox) attenuated allodynia and hyperalgesia. Biochemical analysis revealed that the mRNA and proteins levels of TLR4 were unregulated following CCI to the sciatic nerve, which was then blocked by intrathecal administration of LvOn-siTLR4 with Dox. The LvOn-siTLR4 was also demonstrated to have no effect on TLR4 or the pain response without Dox, which indicated that the expression of siRNA was Dox-inducible in the lentivirus delivery system. In conclusion, TLR4 may serve a significant role in neuropathy and the results of the present study provide an inducible lentivirus-mediated siRNA against TLR4 that may serve as a potential novel strategy to be applied in gene therapy for NP in the future.
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Affiliation(s)
- Yantao Liu
- Department of Anesthesiology and Intensive Care, Shanghai Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Yan Zhang
- Department of Anesthesiology, Zhejiang Zhoushan Hospital, Zhoushan, Zhejiang 316021, P.R. China
| | - Ruirui Pan
- Department of Anesthesiology and Intensive Care, Shanghai Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Mo Chen
- Department of Anesthesiology and Intensive Care, Shanghai Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Xiaoqiang Wang
- Department of Anesthesiology and Intensive Care, Shanghai Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Erliang Kong
- Department of Anesthesiology and Intensive Care, Shanghai Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Weifeng Yu
- Department of Anesthesiology and Intensive Care, Shanghai Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Yuming Sun
- Department of Anesthesiology and Intensive Care, Shanghai Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
| | - Feixiang Wu
- Department of Anesthesiology and Intensive Care, Shanghai Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai 200438, P.R. China
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28
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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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29
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Xing F, Zhang W, Wen J, Bai L, Gu H, Li Z, Zhang J, Tao YX, Xu JT. TLR4/NF-κB signaling activation in plantar tissue and dorsal root ganglion involves in the development of postoperative pain. Mol Pain 2018; 14:1744806918807050. [PMID: 30270727 PMCID: PMC6196615 DOI: 10.1177/1744806918807050] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Background Severe postoperative pain remains a clinical problem that impacts patient’s rehabilitation. The present work aims to investigate the role of Toll-like receptor-4 (TLR4) activation in wounded plantar tissue and dorsal root ganglion (DRG) in the genesis of postoperative pain and its underlying mechanisms. Results Postoperative pain was induced by plantar incision in rat hind paw. Plantar incision led to increased expression of TLR4 in ipsilateral lumbar 4–5 (L4/L5) DRGs, which occurred at 2 h and was persistent to the third day after surgery. Similar to the change in TLR4 expression, there was also significant increase in phosphorylated nuclear factor-kappa B p65 (p-p65) in DRGs after surgery. Immunofluorescence staining revealed that the increased expressions of TLR4 and p-p65 not only in neuronal cells but also in satellite glial cells in DRG. Furthermore, the enhanced expressions of TLR4 and p-p65 were also detected in plantar tissues around the incision, which was observed starting at 2 h and lasting until the third day after surgery. Prior intrathecal (i.t.) injections of TAK-242 (a TLR4-specific antagonist) or 4',6-diamidino-2-phenylindole-dihydrochloride (PDTC, a nuclear factor-kappa B activation inhibitor) dose dependently alleviated plantar incision-induced mechanical allodynia and thermal hyperalgesia and inhibited the increased expressions of p-p65, tumor necrosis factor-alpha, and interleukin-1 beta in DRG. Prior subcutaneous (s.c.) plantar injection of TAK-242 or PDTC also ameliorated pain-related hypersensitivity following plantar incision. Moreover, the plantar s.c. injection of TAK-242 or PDTC inhibited the increased expressions of p-p65, tumor necrosis factor-alpha, and interleukin-1 beta not only in local wounded plantar tissue but also dramatically in ipsilateral lumbar 4–5 DRGs. Conclusion TLR4/ nuclear factor-kappa B signaling activation in local injured tissue and DRG contribute to the development of postoperative pain via regulating pro-inflammatory cytokines release. Targeting TLR4/ nuclear factor-kappa B signaling in local tissue at early stage of surgery may be an effective strategy for the treatment of postoperative pain.
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Affiliation(s)
- Fei Xing
- 1 Department of Anesthesiology, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China.,2 Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Wei Zhang
- 1 Department of Anesthesiology, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China.,3 Neuroscience Research Institute, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Jing Wen
- 1 Department of Anesthesiology, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China
| | - Liying Bai
- 1 Department of Anesthesiology, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China
| | - Hanwen Gu
- 1 Department of Anesthesiology, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China.,2 Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Zhisong Li
- 1 Department of Anesthesiology, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China.,3 Neuroscience Research Institute, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Jian Zhang
- 2 Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Yuan-Xiang Tao
- 3 Neuroscience Research Institute, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Ji-Tian Xu
- 1 Department of Anesthesiology, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China.,2 Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
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30
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Liu Y, Liu W, Wang X, Wan Z, Liu Y, Leng Y. Dexmedetomidine Relieves Acute Inflammatory Visceral Pain in Rats through the ERK Pathway, Toll-Like Receptor Signaling, and TRPV1 Channel. J Mol Neurosci 2018; 66:279-290. [PMID: 30259406 DOI: 10.1007/s12031-018-1172-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 09/13/2018] [Indexed: 01/13/2023]
Abstract
Dexmedetomidine (DEX) is a highly selective α2 adrenergic receptor agonist. In this study, we aimed to characterize the antinociceptive effects of DEX in acute inflammatory visceral pain (AIVP) induced by acetic acid in rats and to evaluate whether antinociception was regulated by the extracellular signal-regulated protein kinase (ERK) pathway, Toll-like receptor (TLR) signaling, and transient receptor potential (TRP) channel. Acetic acid was administered to 30 male rats with or without DEX. Rats were divided into six groups, as follows: control, disease (received no treatment before acetic acid administration), vehicle-treated, low-dose DEX (lDEX), medium-dose DEX (mDEX), and high-dose DEX (hDEX)-treated groups. Thermal withdrawal latency (TWL), mechanical withdrawal threshold (MWT), and abdominal withdrawal reflex (AWR) were measured to assess pain. We detected electromyographic (EGM) responses in the rectus abdominis muscle and measured the average arterial blood pressure. Levels of interleukin 1 (IL-1), IL-2, and IL-6 in the serum, as well as tumor necrosis factor α (TNF-α) and prostaglandin E2 (PGE2) in the peritoneal fluid, were measured by ELISA. The expression levels of phospho(p)CREB, pERK1/2, pMEK1, and TRP cation channel subfamily V member 1 (TRPV1), as well as the activation state of TLR4, were determined in the spinal cord of rats by real-time polymerase chain reaction and western blot analysis. TWL and MWT scores were elevated (P < 0.05) in the hDEX and mDEX groups, whereas AWR scores decreased (P < 0.01), compared to those in the disease group. The medium and high doses of DEX suppressed IL-1, IL-6, TNF-α, and PGE2 release, and increased IL-2 release. In addition, protein and mRNA levels of MEK, ERK, and CREB were reduced in the mDEX and hDEX groups. Moreover, TLR4 and its downstream target, nuclear factor kappa B, along with calcitonin gene-related peptide release through the TRPV1 channel, were suppressed by mDEX and hDEX treatment. Taken together, our results suggest that DEX might exert an antinociceptive effect in AIVP in rats through the MEK/ERK pathway, TLR signaling, and TRPV1 channel, resulting in suppression of visceral hypersensitivity.
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Affiliation(s)
- Yatao Liu
- Department of anesthesiology, First Hospital of Lanzhou University, No. 1 Donggang Xi Road , Chengguan District, Lanzhou, 730000, Gansu, China
| | - Wei Liu
- Department of Pathology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, Gansu, China
| | - Xiaoqing Wang
- Department of anesthesiology, First Hospital of Lanzhou University, No. 1 Donggang Xi Road , Chengguan District, Lanzhou, 730000, Gansu, China
| | - Zhanhai Wan
- Department of anesthesiology, First Hospital of Lanzhou University, No. 1 Donggang Xi Road , Chengguan District, Lanzhou, 730000, Gansu, China
| | - Yongqiang Liu
- Department of anesthesiology, First Hospital of Lanzhou University, No. 1 Donggang Xi Road , Chengguan District, Lanzhou, 730000, Gansu, China
| | - Yufang Leng
- Department of anesthesiology, First Hospital of Lanzhou University, No. 1 Donggang Xi Road , Chengguan District, Lanzhou, 730000, Gansu, China.
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Water-Soluble Polymer Assists N-Methyl-D-Aspartic Acid Receptor 2B siRNA Delivery to Relieve Chronic Inflammatory Pain In Vitro and In Vivo. Pain Res Manag 2018; 2018:7436060. [PMID: 29623145 PMCID: PMC5829431 DOI: 10.1155/2018/7436060] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 09/03/2017] [Accepted: 10/16/2017] [Indexed: 11/24/2022]
Abstract
We constructed a water-soluble lipopolymer (WSLP) as a nonviral gene carrier to deliver siRNA targeting NR2B. The cytotoxicity and serum stability of WSLP loaded with siRNA were evaluated, and the knockdown efficiency of WSLP/NR2B-siRNA in PC12 cells was examined. The results showed that WSLP could protect the loading siRNAs from enzymatic degradation in serum and exhibit low cytotoxicity to cells. After transfection, WSLP/NR2B-siRNA complexes reduced the NR2B transcriptional level by 50% and protein level by 55% compared to control siRNA. Moreover, 3 days after intrathecal injection of WSLP/NR2B-siRNA complexes into rats, the NR2B protein expression decreased significantly to 58%, compared to control treatment (p < 0.01). Injection of WSLP with scrambled siRNA or of polyethylenimine (PEI) with NR2B-siRNA did not show this inhibitory effect. Additionally, injection of WSLP/NR2B-siRNA complexes significantly relieved inflammatory pain in rats at 3, 4, and 5 days with reduced MWT and decreased TWL scores, while injection of WSLP with scrambled siRNA or of PEI with NR2B-siRNA did not. These results demonstrated that WSLP can efficiently deliver siRNA targeting NR2B to PC12 cells and relieve pain in rats with chronic inflammatory pain.
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Ren H, Jin H, Jia Z, Ji N, Luo F. Pulsed Radiofrequency Applied to the Sciatic Nerve Improves Neuropathic Pain by Down-regulating The Expression of Calcitonin Gene-related Peptide in the Dorsal Root Ganglion. Int J Med Sci 2018; 15:153-160. [PMID: 29333099 PMCID: PMC5765728 DOI: 10.7150/ijms.20501] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 07/06/2017] [Indexed: 01/12/2023] Open
Abstract
Background: Clinical studies have shown that applying pulsed radiofrequency (PRF) to the neural stem could relieve neuropathic pain (NP), albeit through an unclear analgesic mechanism. And animal experiments have indicated that calcitonin gene-related peptide (CGRP) expressed in the dorsal root ganglion (DRG) is involved in generating and maintaining NP. In this case, it is uncertain whether PRF plays an analgesic role by affecting CGRP expression in DRG. Methods: Rats were randomly divided into four groups: Groups A, B, C, and D. In Groups C and D, the right sciatic nerve was ligated to establish the CCI model, while in Groups A and B, the sciatic nerve was isolated without ligation. After 14 days, the right sciatic nerve in Groups B and D re-exposed and was treated with PRF on the ligation site. Thermal withdrawal latency (TWL) and hindpaw withdrawal threshold (HWT) were measured before PRF treatment (Day 0) as well as after 2, 4, 8, and 14 days of treatment. At the same time points of the behavioral tests, the right L4-L6 DRG was sampled and analyzed for CGRP expression using RT-qPCR and an enzyme-linked immunosorbent assay (ELISA). Results: Fourteen days after sciatic nerve ligation, rats in Groups C and D had a shortened TWL (P<0.001) and a reduced HWT (P<0.001) compared to those in Groups A and B. After PRF treatment, the TWL of the rats in Group D gradually extended with HWT increasing progressively. Prior to PRF treatment (Day 0), CGRP mRNA expressions in the L4-L6 DRG of Groups C and D increased significantly (P<0.001) and were 2.7 and 2.6 times that of Group A respectively. ELISA results showed that the CGRP content of Groups C and D significantly increased in comparison with that of Groups A and B (P<0.01). After PRF treatment, the mRNA expression in the DRG of Group D gradually decreased and the mRNA expression was 1.7 times that of Group A on the 4th day(P> 0.05). On the 8th and 14th days, the mRNA levels in Group D were restored to those of Groups A and B. Meanwhile, the CGRP content of Group D gradually dropped over time, from 76.4 pg/mg (Day 0) to 57.5 pg/mg (Day 14). Conclusions: In this study, we found that, after sciatic nerve ligation, rats exhibited apparent hyperalgesia and allodynia, and CGRP mRNA and CGRP contents in the L4-L6 DRG increased significantly. Through lowering CGRP expression in the DRG, PRF treatment might relieve the pain behaviors of NP.
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Affiliation(s)
- Hao Ren
- Department of Anesthesiology and Pain Management, Beijing Tiantan Hospital, Capital Medical University
| | - Hailong Jin
- Department of Anesthesiology and Pain Management, Beijing Tiantan Hospital, Capital Medical University
| | - Zipu Jia
- Department of Anesthesiology and Pain Management, Beijing Tiantan Hospital, Capital Medical University
| | - Nan Ji
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University
| | - Fang Luo
- Department of Anesthesiology and Pain Management, Beijing Tiantan Hospital, Capital Medical University
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Jin G, Jin X, Zhou S. Sparstolonin B selectively suppresses toll‑like receptor‑2 and ‑4 to alleviate neuropathic pain. Mol Med Rep 2017; 17:1247-1252. [PMID: 29115627 DOI: 10.3892/mmr.2017.7951] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 05/22/2017] [Indexed: 11/06/2022] Open
Abstract
It has been previously demonstrated that sparstolonin B (SsnB) inhibits toll‑like receptor (TLR)‑2 and TLR‑4. The present study investigated the effect of SsnB on neuropathic pain (NP). A chronic constriction injury (CCI) model was constructed in rats and the protein expression of TLR‑2 and TLR‑4 was determined by western blot analysis. Rats were divided into the following three groups: Rats with sham surgery (control group); rats with CCI (model group); and rats with CCI and injection of SsnB (SsnB group). The mechanical withdrawal threshold (MWT) was measured by using Von Frey filaments. In addition, the mRNA and protein expression levels of nuclear factor‑κB (NF‑κB) were investigated by reverse transcription‑quantitative polymerase chain reaction and western blot analysis, respectively, and the concentrations of tumor necrosis factor‑α (TNF‑α) and interleukin (IL)‑6 were determined by ELISA. Compared with control rats, the protein expression levels of TLR‑2 and TLR‑4 were increased in model rats (P<0.001). At 7 and 14 days after surgery, the MWTs in the model group were significantly reduced compared with the control group (P<0.001). However, the MWTs in the SsnB group were significantly increased compared with the model group (P<0.001). The results also demonstrated that the mRNA and protein expression levels of NF‑κB, and the protein expression levels of TNF‑α and IL‑6, were increased in model group compared with the control group (P<0.001). Furthermore, these increases in expression were all reduced in the SsnB group compared with the model group. Therefore, the results indicate that SsnB may alleviate NP via suppression of TLR‑2 and TLR‑4, and may be a potential drug for the treatment of NP.
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Affiliation(s)
- Guanghui Jin
- Department of Anesthesiology, Affiliated Hospital of Beihua University, Jilin, Jilin 132000, P.R. China
| | - Xing Jin
- Department of Anesthesiology, Affiliated Hospital of Beihua University, Jilin, Jilin 132000, P.R. China
| | - Shuang Zhou
- Department of Anesthesiology, Affiliated Hospital of Beihua University, Jilin, Jilin 132000, P.R. China
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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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Pan LF, Yu L, Wang LM, He JT, Sun JL, Wang XB, Bai ZH, Wang H, Yan TL, Pei HH. The Toll-like receptor 4 antagonist TAK-242 protects against chronic pancreatitis in rats. Mol Med Rep 2017; 16:3863-3868. [PMID: 28765897 PMCID: PMC5646963 DOI: 10.3892/mmr.2017.7105] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 07/04/2017] [Indexed: 02/05/2023] Open
Abstract
Chronic pancreatitis is a progressive disease characterized by irreversible morphological changes to the pancreas, typically causing pain and permanent loss of function. It is a poorly understood disease with the pathogenesis remaining unclear. The authors' previous data demonstrated that the inhibition of Toll‑like receptor 4 (TLR4) using TLR4 antagonist kinase (TAK)‑242 attenuates taurocholate‑induced oxidative stress via the regulation of mitochondrial function in the pancreatic acinar cells of mice. In the present study, the effect of TAK‑242 on trinitrobenzene sulfonic acid (TNBS)‑induced chronic pancreatitis was investigated in rats. The results revealed that TAK‑242 attenuated the severity of chronic pancreatic injury, and regulated extracellular matrix secretion and cellular immunity. In addition, TAK‑242 treatment significantly decreased cell apoptosis, as evidenced by the reduction in Terminal deoxynucleotidyl transferase dUTP nick end labeling‑positive cells in pancreas tissue sections, and also promoted cell proliferation in TNBS‑treated animals. Furthermore, the results of the calibrated von Frey filament assay demonstrated that TAK‑242 could prevent the pancreatitis‑induced referred abdominal hypersensitivity. In summary, TAK‑242 exhibits protective effects against TNBS‑induced chronic pancreatitis and may be a potential therapeutic strategy for the treatment of patients with chronic pancreatitis.
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Affiliation(s)
- Long-Fei Pan
- Department of Emergency Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China
| | - Lei Yu
- Department of Basic Medicine, Xi'an Medical College, Xi'an, Shaanxi 710021, P.R. China
| | - Li-Ming Wang
- Department of Emergency Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China
| | - Jun-Tao He
- Department of Clinical Laboratory, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China
| | - Jiang-Li Sun
- Department of Emergency Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China
| | - Xiao-Bo Wang
- Department of Emergency Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China
| | - Zheng-Hai Bai
- Department of Emergency Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China
| | - Hai Wang
- Department of Emergency Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China
| | - Ting-Lin Yan
- Department of Forensic Medicine, Health Science Center of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Hong-Hong Pei
- Department of Emergency Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China
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Early alterations of Hedgehog signaling pathway in vascular endothelial cells after peripheral nerve injury elicit blood-nerve barrier disruption, nerve inflammation, and neuropathic pain development. Pain 2017; 157:827-839. [PMID: 26655733 DOI: 10.1097/j.pain.0000000000000444] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Changes in the nerve's microenvironment and local inflammation resulting from peripheral nerve injury participate in nerve sensitization and neuropathic pain development. Taking part in these early changes, disruption of the blood-nerve barrier (BNB) allows for infiltration of immunocytes and promotes the neuroinflammation. However, molecular mechanisms engaged in vascular endothelial cells (VEC) dysfunction and BNB alterations remain unclear. In vivo, BNB permeability was assessed following chronic constriction injury (CCI) of the rat sciatic nerve (ScN) and differential expression of markers of VEC functional state, inflammation, and intracellular signaling was followed from 3 hours to 2 months postinjury. Several mechanisms potentially involved in functional alterations of VEC were evaluated in vitro using human VEC (hCMEC/D3), then confronted to in vivo physiopathological conditions. CCI of the ScN led to a rapid disruption of endoneurial vascular barrier that was correlated to a decreased production of endothelial tight-junction proteins and an early and sustained alteration of Hedgehog (Hh) signaling pathway. In vitro, activation of Toll-like receptor 4 in VEC downregulated the components of Hh pathway and altered the endothelial functional state. Inhibition of Hh signaling in the ScN of naive rats mimicked the biochemical and functional alterations observed after CCI and was, on its own, sufficient to evoke local neuroinflammation and sustained mechanical allodynia. Alteration of the Hh signaling pathway in VEC associated with peripheral nerve injury, is involved in BNB disruption and local inflammation, and could thus participate in the early changes leading to the peripheral nerve sensitization and, ultimately, neuropathic pain development.
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Alqinyah M, Maganti N, Ali MW, Yadav R, Gao M, Cacan E, Weng HR, Greer SF, Hooks SB. Regulator of G Protein Signaling 10 (Rgs10) Expression Is Transcriptionally Silenced in Activated Microglia by Histone Deacetylase Activity. Mol Pharmacol 2016; 91:197-207. [PMID: 28031332 DOI: 10.1124/mol.116.106963] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 12/12/2016] [Indexed: 02/06/2023] Open
Abstract
RGS10 has emerged as a key regulator of proinflammatory cytokine production in microglia, functioning as an important neuroprotective factor. Although RGS10 is normally expressed in microglia at high levels, expression is silenced in vitro following activation of TLR4 receptor. Given the ability of RGS10 to regulate inflammatory signaling, dynamic regulation of RGS10 levels in microglia may be an important mechanism to tune inflammatory responses. The goals of the current study were to confirm that RGS10 is suppressed in an in vivo inflammatory model of microglial activation and to determine the mechanism for activation-dependent silencing of Rgs10 expression in microglia. We demonstrate that endogenous RGS10 is present in spinal cord microglia, and RGS10 protein levels are suppressed in the spinal cord in a nerve injury-induced neuropathic pain mouse model. We show that the histone deacetylase (HDAC) enzyme inhibitor trichostatin A blocks the ability of lipopolysaccharide (LPS) to suppress Rgs10 transcription in BV-2 and primary microglia, demonstrating that HDAC enzymes are required for LPS silencing of Rgs10 Furthermore, we used chromatin immunoprecipitation to demonstrate that H3 histones at the Rgs10 proximal promoter are deacetylated in BV-2 microglia following LPS activation, and HDAC1 association at the Rgs10 promoter is enhanced following LPS stimulation. Finally, we have shown that sphingosine 1-phosphate, an endogenous microglial signaling mediator that inhibits HDAC activity, enhances basal Rgs10 expression in BV-2 microglia, suggesting that Rgs10 expression is dynamically regulated in microglia in response to multiple signals.
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Affiliation(s)
- Mohammed Alqinyah
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia (M.A., M.W.A., R.Y., M.G., H.-R.W., S.B.H.); and Department of Biology, Georgia State University, Atlanta, Georgia (N.M., E.C., S.F.G.)
| | - Nagini Maganti
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia (M.A., M.W.A., R.Y., M.G., H.-R.W., S.B.H.); and Department of Biology, Georgia State University, Atlanta, Georgia (N.M., E.C., S.F.G.)
| | - Mourad W Ali
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia (M.A., M.W.A., R.Y., M.G., H.-R.W., S.B.H.); and Department of Biology, Georgia State University, Atlanta, Georgia (N.M., E.C., S.F.G.)
| | - Ruchi Yadav
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia (M.A., M.W.A., R.Y., M.G., H.-R.W., S.B.H.); and Department of Biology, Georgia State University, Atlanta, Georgia (N.M., E.C., S.F.G.)
| | - Mei Gao
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia (M.A., M.W.A., R.Y., M.G., H.-R.W., S.B.H.); and Department of Biology, Georgia State University, Atlanta, Georgia (N.M., E.C., S.F.G.)
| | - Ercan Cacan
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia (M.A., M.W.A., R.Y., M.G., H.-R.W., S.B.H.); and Department of Biology, Georgia State University, Atlanta, Georgia (N.M., E.C., S.F.G.)
| | - Han-Rong Weng
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia (M.A., M.W.A., R.Y., M.G., H.-R.W., S.B.H.); and Department of Biology, Georgia State University, Atlanta, Georgia (N.M., E.C., S.F.G.)
| | - Susanna F Greer
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia (M.A., M.W.A., R.Y., M.G., H.-R.W., S.B.H.); and Department of Biology, Georgia State University, Atlanta, Georgia (N.M., E.C., S.F.G.)
| | - Shelley B Hooks
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia (M.A., M.W.A., R.Y., M.G., H.-R.W., S.B.H.); and Department of Biology, Georgia State University, Atlanta, Georgia (N.M., E.C., S.F.G.)
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Guerrero ATG, Pinto LG, Cunha FQ, Ferreira SH, Alves-Filho JC, Verri WA, Cunha TM. Mechanisms underlying the hyperalgesic responses triggered by joint activation of TLR4. Pharmacol Rep 2016; 68:1293-1300. [PMID: 27689757 DOI: 10.1016/j.pharep.2016.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 08/15/2016] [Accepted: 08/23/2016] [Indexed: 01/04/2023]
Abstract
BACKGROUND Toll-like receptors (TLRs) including TLR4 and their signal pathways contribute to the pathogenesis of arthritis. Herein, we evaluated the mechanisms underlying the hyperalgesic response caused by TLR4 activation in the tibio-tarsal joint in mice. METHODS Joint inflammatory hyperalgesia was induced by intra-articular (ia) injection of LPS (lipopolysaccharide- TLR4 agonist) in C57BL/6, TLR4, TLR2, MyD88, TRIF, TNFR1/2 and IL-1R1 knockout (-/-) mice. Joint hyperalgesia was evaluated using an electronic von Frey. Neutrophil recruitment was assessed by MPO activity. Joint levels of cytokines were measured by ELISA. RESULTS Firstly, it was shown that LPS injected into the joints causes a dose- and time-dependent reduction in the mechanical nociceptive threshold. The TLR4 activation in the joint triggers mechanical hyperalgesia and neutrophil migration, which was abolished in TLR4 -/- and MyD88-/-, but not in TLR2-/- and TRIF-/- mice. Besides, joint administration of LPS increased the release of TNF-α, IL-1β, and KC/CXCL1, which were reduced in TLR4-/- and MyD88-/-, but not in TRIF-/- mice. In agreement, the LPS-induced joint nociceptive effect was decreased in TNFR1/2-/- and IL-1R1-/- mice or in mice pre-treated with a CXCR1/2 selective antagonist (DF2156A). CONCLUSIONS These results suggest that TLR4 activation in the joint produces articular hyperalgesia via MyD88 signaling pathway. Moreover, this pathway is involved in the cascade of events of articular hyperalgesia through mechanisms dependent on cytokines and chemokines production. Thus, TLR4/MyD88 signaling pathway inhibitors might be useful for the treatment of inflammatory joint pain.
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Affiliation(s)
- Ana T G Guerrero
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Avenida Bandeirantes, 3900, 14049-900 Ribeirão Preto, São Paulo, Brazil; Fundação Oswaldo Cruz-FIOCRUZ Mato Grosso do Sul, Rua Gabriel Abrão 92, 79081-746 Campo Grande, Mato Grosso do Sul, Brazil.
| | - Larissa G Pinto
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Avenida Bandeirantes, 3900, 14049-900 Ribeirão Preto, São Paulo, Brazil.
| | - Fernando Q Cunha
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Avenida Bandeirantes, 3900, 14049-900 Ribeirão Preto, São Paulo, Brazil.
| | - Sérgio H Ferreira
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Avenida Bandeirantes, 3900, 14049-900 Ribeirão Preto, São Paulo, Brazil.
| | - Jose C Alves-Filho
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Avenida Bandeirantes, 3900, 14049-900 Ribeirão Preto, São Paulo, Brazil.
| | - Waldiceu A Verri
- Departamento de Patologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Paraná, Rod. Celso Garcia Cid Km380 PR445, 86057-970 Londrina, Paraná, Brazil.
| | - Thiago M Cunha
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Avenida Bandeirantes, 3900, 14049-900 Ribeirão Preto, São Paulo, Brazil.
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Kato J, Agalave NM, Svensson CI. Pattern recognition receptors in chronic pain: Mechanisms and therapeutic implications. Eur J Pharmacol 2016; 788:261-273. [PMID: 27343378 DOI: 10.1016/j.ejphar.2016.06.039] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 06/22/2016] [Accepted: 06/22/2016] [Indexed: 12/13/2022]
Abstract
For the individual, it is vital to promptly detect and recognize a danger that threatens the integrity of the body. Pattern recognition receptors (PRRs) are several classes of protein families originally classified as receptors detecting exogenous pathogens. PRRs are also capable of recognizing molecules released from damaged tissues (damage-associated molecular pattern molecules; DAMPs) and thereby contribute to danger recognition. Importantly, it is now evident that PRRs, such as toll-like receptors (TLRs) and receptors for advanced glycation end products (RAGE), are not only expressed in peripheral immune cells but also present in neurons and glial cells in the nervous system. These PRR-expressing cells work in concert, enabling highly sensitive danger recognition. However, this sensitiveness can act as a double-edged sword. Accumulated evidence has led to the hypothesis that aberrant activation of PRRs may play a crucial role in the pathogenesis of pathological pain. Indeed, numerous studies employing gene deletion or pharmacological inhibition of PRRs successfully reversed or prevented pathological pain in experimental animal models. Furthermore, a number of preclinical studies have shown the therapeutic potential of targeting PRRs for chronic pain. Here, we review the current knowledge regarding the role of PRRs in chronic pain and discuss the promise and challenges of targeting PRRs as a novel therapeutic approach for chronic pain.
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Affiliation(s)
- Jungo Kato
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
| | - Nilesh M Agalave
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Camilla I Svensson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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Tramullas M, Finger BC, Dinan TG, Cryan JF. Obesity Takes Its Toll on Visceral Pain: High-Fat Diet Induces Toll-Like Receptor 4-Dependent Visceral Hypersensitivity. PLoS One 2016; 11:e0155367. [PMID: 27159520 PMCID: PMC4861320 DOI: 10.1371/journal.pone.0155367] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 04/27/2016] [Indexed: 12/30/2022] Open
Abstract
Exposure to high-fat diet induces both, peripheral and central alterations in TLR4 expression. Moreover, functional TLR4 is required for the development of high-fat diet-induced obesity. Recently, central alterations in TLR4 expression have been associated with the modulation of visceral pain. However, it remains unknown whether there is a functional interaction between the role of TLR4 in diet-induced obesity and in visceral pain. In the present study we investigated the impact of long-term exposure to high-fat diet on visceral pain perception and on the levels of TLR4 and Cd11b (a microglial cell marker) protein expression in the prefrontal cortex (PFC) and hippocampus. Peripheral alterations in TLR4 were assessed following the stimulation of spleenocytes with the TLR4-agonist LPS. Finally, we evaluated the effect of blocking TLR4 on visceral nociception, by administering TAK-242, a selective TLR4-antagonist. Our results demonstrated that exposure to high-fat diet induced visceral hypersensitivity. In parallel, enhanced TLR4 expression and microglia activation were found in brain areas related to visceral pain, the PFC and the hippocampus. Likewise, peripheral TLR4 activity was increased following long-term exposure to high-fat diet, resulting in an increased level of pro-inflammatory cytokines. Finally, TLR4 blockage counteracted the hyperalgesic phenotype present in mice fed on high-fat diet. Our data reveal a role for TLR4 in visceral pain modulation in a model of diet-induced obesity, and point to TLR4 as a potential therapeutic target for the development of drugs to treat visceral hypersensitivity present in pathologies associated to fat diet consumption.
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Affiliation(s)
- Mónica Tramullas
- APC Microbiome Institute, University College Cork, Cork, Ireland
- * E-mail:
| | | | - Timothy G. Dinan
- APC Microbiome Institute, University College Cork, Cork, Ireland
- Department of Psychiatry & Neurobehavioural Science, University College Cork, Cork, Ireland
| | - John F. Cryan
- APC Microbiome Institute, University College Cork, Cork, Ireland
- Department of Anatomy & Neuroscience, University College Cork, Cork, Ireland
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García Bueno B, Caso JR, Madrigal JLM, Leza JC. Innate immune receptor Toll-like receptor 4 signalling in neuropsychiatric diseases. Neurosci Biobehav Rev 2016; 64:134-47. [PMID: 26905767 DOI: 10.1016/j.neubiorev.2016.02.013] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 11/27/2015] [Accepted: 02/12/2016] [Indexed: 02/08/2023]
Abstract
The innate immunity is a stereotyped first line of defense against pathogens and unspecified damage signals. One of main actors of innate immunity are the Toll-like receptors (TLRs), and one of the better characterized members of this family is TLR-4, that it is mainly activated by Gram-negative bacteria lipopolysaccharide. In brain, TLR-4 organizes innate immune responses against infections or cellular damage, but also possesses other physiological functions. In the last years, some evidences suggest a role of TLR-4 in stress and stress-related neuropsychiatric diseases. Peripheral and brain TLR-4 activation triggers sickness behavior, and its expression is a risk factor of depression. Some elements of the TLR-4 signaling pathway are up-regulated in peripheral samples and brain post-mortem tissue from depressed and suicidal patients. The "leaky gut" hypothesis of neuropsychiatric diseases is based on the existence of an increase of the intestinal permeability which results in bacterial translocation able to activate TLR-4. Enhanced peripheral TLR-4 expression/activity has been described in subjects diagnosed with schizophrenia, bipolar disorder and in autistic children. A role for TLR-4 in drugs abuse has been also proposed. The therapeutic potential of pharmacological/genetic modulation of TLRs signaling pathways in neuropsychiatry is promising, but a great preclinical/clinical scientific effort is still needed.
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Affiliation(s)
- B García Bueno
- Department of Pharmacology, School of Medicine, Complutense University, CIBERSAM, Instituto de Investigación Hospital 12 de Octubre (Imas12), 28040 Madrid, Spain.
| | - J R Caso
- Department of Pharmacology, School of Medicine, Complutense University, CIBERSAM, Instituto de Investigación Hospital 12 de Octubre (Imas12), 28040 Madrid, Spain.
| | - J L M Madrigal
- Department of Pharmacology, School of Medicine, Complutense University, CIBERSAM, Instituto de Investigación Hospital 12 de Octubre (Imas12), 28040 Madrid, Spain.
| | - J C Leza
- Department of Pharmacology, School of Medicine, Complutense University, CIBERSAM, Instituto de Investigación Hospital 12 de Octubre (Imas12), 28040 Madrid, Spain.
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Blockade of Toll-Like Receptors (TLR2, TLR4) Attenuates Pain and Potentiates Buprenorphine Analgesia in a Rat Neuropathic Pain Model. Neural Plast 2015; 2016:5238730. [PMID: 26962463 PMCID: PMC4709736 DOI: 10.1155/2016/5238730] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 09/07/2015] [Accepted: 09/20/2015] [Indexed: 02/07/2023] Open
Abstract
Accumulating evidence indicates that microglial TLR2 and TLR4 play a significant role in nociception. Experiments were conducted to evaluate the contribution of TLR2 and TLR4 and their adaptor molecules to neuropathy and their ability to amplify opioid effectiveness. Behavioral tests (von Frey's and cold plate) and biochemical (Western blot and qRT-PCR) analysis of spinal cord and DRG tissue were conducted after chronic constriction injury (CCI) to the sciatic nerve. Repeated intrathecal administration of LPS-RS (TLR2 and TLR4 antagonist) and LPS-RS Ultrapure (TLR4 antagonist) attenuated allodynia and hyperalgesia. Biochemical analysis revealed time-dependent upregulation of mRNA and/or protein levels of TLR2 and TLR4 and MyD88 and TRIF adaptor molecules, which was paralleled by an increase in IBA-1/CD40-positive cells under neuropathy. LPS-RS and LPS-RS Ultrapure similarly influenced opioid analgesia by enhancing the effectiveness of buprenorphine but not morphine. Summing up, in light of their upregulation over the course of pain, both TLR2 and TLR4 may indeed play a significant role in neuropathy, which could be linked to the observed activation of IBA-1/CD40-positive cells. Blockade of TLR2 and TLR4 produced analgesia and enhanced buprenorphine's effectiveness, which suggests that they may be a putative target for future pharmacological pain relief tools, especially for opioid rotation, when the effect of morphine is tolerated.
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Helley M, Abate W, Jackson S, Bennett J, Thompson S. The expression of Toll-like receptor 4, 7 and co-receptors in neurochemical sub-populations of rat trigeminal ganglion sensory neurons. Neuroscience 2015; 310:686-98. [DOI: 10.1016/j.neuroscience.2015.09.069] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/03/2015] [Accepted: 09/25/2015] [Indexed: 12/12/2022]
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Inducible Lentivirus-Mediated siRNA against TLR4 Reduces Nociception in a Rat Model of Bone Cancer Pain. Mediators Inflamm 2015; 2015:523896. [PMID: 26556957 PMCID: PMC4628653 DOI: 10.1155/2015/523896] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/26/2015] [Accepted: 08/10/2015] [Indexed: 01/28/2023] Open
Abstract
Although bone cancer pain is still not fully understood by scientists and clinicians alike, studies suggest that toll like receptor 4 (TLR4) plays an important role in the initiation and/or maintenance of pathological pain state in bone cancer pain. A promising treatment for bone cancer pain is the downregulation of TLR4 by RNA interference; however, naked siRNA (small interference RNA) is not effective in long-term treatments. In order to concoct a viable prolonged treatment for bone cancer pain, an inducible lentivirus LvOn-siTLR4 (tetracycline inducible lentivirus carrying siRNA targeting TLR4) was prepared and the antinociception effects were observed in bone cancer pain rats induced by Walker 256 cells injection in left leg. Results showed that LvOn-siTLR4 intrathecal injection with doxycycline (Dox) oral administration effectively reduced the nociception induced by Walker 256 cells while inhibiting the mRNA and protein expression of TLR4. Proinflammatory cytokines as TNF-α and IL-1β in spinal cord were also decreased. These findings suggest that TLR4 could be a target for bone cancer pain treatment and tetracycline inducible lentivirus LvOn-siTLR4 represents a new potential option for long-term treatment of bone cancer pain.
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Zhao Y, Xin Y, Gao J, Teng RY, Chu HC. Analgesic effect of TAK-242 on neuropathic pain in rats. Int J Clin Exp Med 2015; 8:11202-11207. [PMID: 26379924 PMCID: PMC4565307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/21/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND The current study investigated the analgesic effect of the Toll-like receptor 4 (TLR4) specific antagonist TAK-242 on neuropathic pain in rats and its underlying mechanism. METHODS A total of 132 adult Sprague-Dawley (SD) rats were randomly divided into four groups: the sham operation group, the neuropathic pain model group, the TAK-242 low-dose treatment group, and the TAK-242 high-dose treatment group. The heat pain and mechanic pain thresholds of rats were detected on preoperative day 1 and postoperative days 1, 3, 7, and 10. The expression levels of IκBα, p65, IL-1β, and TNF-α in the spinal cord dorsal horn were detected on postoperative day 7 in one group of rats. RESULTS Compared with rats in the sham operation group, the heat pain and mechanic pain thresholds of the rats in the neuropathic pain model group significantly decreased; their expression levels of p65, IL-1β, and TNF-α significantly increased; and their expression level of IkBα significantly decreased. Compared with the neuropathic pain group, high doses of TAK-242 significantly inhibited the expression of p65, IL-1β, and TNF-α; significantly increased the expression level of IkBα; and upregulated the heat pain and mechanic pain thresholds. CONCLUSION TAK-242 might improve neuropathic pain through downregulation of the NF-κB pathway.
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Affiliation(s)
- Yang Zhao
- Department of Anesthesiology, The Affiliated Hospital of Qingdao UniversityQingdao 266000, P.R. China
| | - Yan Xin
- Department of Anesthesiology, Qingdao Municipal HospitalQingdao 266000, P.R. China
| | - Jie Gao
- Department of Anesthesiology, The Affiliated Hospital of Qingdao UniversityQingdao 266000, P.R. China
| | - Ru-Yang Teng
- Department of Anesthesiology, The Affiliated Hospital of Qingdao UniversityQingdao 266000, P.R. China
| | - Hai-Chen Chu
- Department of Anesthesiology, The Affiliated Hospital of Qingdao UniversityQingdao 266000, P.R. China
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Chen H, Jiang YS, Sun Y, Xiong YC. p38 and interleukin-1 beta pathway via toll-like receptor 4 contributed to the skin and muscle incision and retraction-induced allodynia. J Surg Res 2015; 197:339-47. [PMID: 25979559 DOI: 10.1016/j.jss.2015.04.061] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Revised: 03/26/2015] [Accepted: 04/15/2015] [Indexed: 12/30/2022]
Abstract
BACKGROUND Persistent postsurgical pain, as an important clinical problem, seriously affects the quality of life in patients. However, the mechanism underlying persistent postsurgical pain remains largely unclear. The present study aims to elucidate the involvement of toll-like receptor 4 (TLR4) and its interaction with p38 and interleukin [IL]-1β signaling in dorsal root ganglion (DRG) in the persistent postsurgical pain. METHODS Skin and muscle incision and retraction (SMIR) surgery-induced paw withdrawal threshold (PWT) change was determined by applying mechanical stimuli to the plantar surface of the hind paw using von Frey hairs. The PE-10 catheter intrathecal placement was used to deliver LPS-RS, interleukin-1 receptor antagonist, or SB203580. Western blot analysis was performed to measure the expression of the TLR4, mitogen-activated protein kinases family, and IL-1β in ipsilateral L3 and L4 DRG. Immunofluorescence staining was performed to further investigate the cell type of TLR4 expression. All data were expressed as means ± standard error of the mean and analyzed using SPSS 13.0. RESULTS The results showed that the SMIR surgery, a rat model of persistent postoperative pain, decreased the ipsilateral 50% PWT, and the decrease lasted for at least 20 d. The expression of TLR4 and phosphorylation of p38 were upregulated in ipsilateral L3 and L4 DRG neurons after SMIR surgery. Pretreatment with LPS-RS, an established TLR4 antagonist, prevented p38 activation and attenuated mechanical allodynia induced by SMIR surgery. In addition, the expression of IL-1β was significantly increased after SMIR surgery. Blocking IL-1β by interleukin-1 receptor antagonist significantly improved the decreased PWT evoked by SMIR. Moreover, inhibition of TLR4 or p38 pathway prevented the IL-1β upregulation and mechanical allodynia induced by SMIR. CONCLUSIONS These findings suggest that the activation of p38 and IL-1β signaling pathway via TLR4 mediate mechanical allodynia after SMIR surgery.
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Affiliation(s)
- Hui Chen
- Department of Anesthesiology and Critical Care, The First Affiliated Hospital, Second Military Medical University, Shanghai, PR China
| | - You-shui Jiang
- Department of Anesthesiology and Critical Care, The First Affiliated Hospital, Second Military Medical University, Shanghai, PR China
| | - Yang Sun
- Department of Pain, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, PR China
| | - Yuan-chang Xiong
- Department of Anesthesiology and Critical Care, The First Affiliated Hospital, Second Military Medical University, Shanghai, PR China.
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Sun Y, Yang M, Tang H, Ma Z, Liang Y, Li Z. The over-production of TNF-α via Toll-like receptor 4 in spinal dorsal horn contributes to the chronic postsurgical pain in rat. J Anesth 2015; 29:734-40. [PMID: 25895164 DOI: 10.1007/s00540-015-2011-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 03/29/2015] [Indexed: 11/29/2022]
Abstract
PURPOSE Many patients suffer from chronic postsurgical pain (CPSP) following surgery, and the underlying mechanisms are poorly understood. In the present work, using the skin/muscle incision retraction (SMIR) model, the role of spinal TLR4/TNF-α pathway in the induction of CPSP was evaluated. METHODS Mechanical allodynia induced by SMIR was established in adult male Sprague-Dawley rats. The von Frey test was performed to evaluate the role of TLR4/TNF-α pathway on the mechanical allodynia. Western-blot and immunohistochemistry methods were adopted to understand the molecular mechanisms. RESULTS SMIR surgery decreased the ipsilateral 50 % paw withdrawal threshold, lasting for at least 20 days. Western-blot analysis and immunohistochemistry revealed that SMIR surgery significantly upregulated the expression of TLR4 (p < 0.01) in glial cells on the ipsilateral side of spinal cord and increased TLR4 occurred on day 5 and was maintained to the end of the experiment (day 20). Similarly, tumor necrosis factor-alpha (TNF-α) was significantly increased on days 5, 10, and 20 on the ipsilateral side of spinal dorsal horn following SMIR surgery. Intraperitoneal injection of an inhibitor of TNF-α synthesis thalidomide at 50 or 100 mg/kg dose (but not 10 mg/kg dose) significantly ameliorated the reduced paw withdrawal threshold induced by SMIR surgery. Importantly, intrathecal delivery of a specific TLR4 antagonist (LPS-RS) at dose of 25 μg significantly attenuated mechanical allodynia and prevented the upregulation of TNF-α induced by SMIR surgery. CONCLUSIONS These findings suggest that the upregulation of TNF-α via TLR4 contributes to the development of CPSP in spinal dorsal horn.
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Affiliation(s)
- Yang Sun
- Department of Pain, The First Affiliated Hospital of Xinjiang Medical University, 137 Liyushan South Road, Urumqi, Xinjiang, 830054, China
| | - Mingmin Yang
- Department of Pain, The First Affiliated Hospital of Xinjiang Medical University, 137 Liyushan South Road, Urumqi, Xinjiang, 830054, China
| | - Hao Tang
- Department of General Internal Medicine, The First Affiliated Hospital of Sun Yat-sen University, Sun Yet-Sen University, 58 Zhongshan Rd. 2, Guangzhou, 510080, China
| | - Zhongfu Ma
- Department of General Internal Medicine, The First Affiliated Hospital of Sun Yat-sen University, Sun Yet-Sen University, 58 Zhongshan Rd. 2, Guangzhou, 510080, China
| | - Yanbing Liang
- Department of General Internal Medicine, The First Affiliated Hospital of Sun Yat-sen University, Sun Yet-Sen University, 58 Zhongshan Rd. 2, Guangzhou, 510080, China
| | - Zhenyu Li
- Department of General Internal Medicine, The First Affiliated Hospital of Sun Yat-sen University, Sun Yet-Sen University, 58 Zhongshan Rd. 2, Guangzhou, 510080, China.
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Paclitaxel induces acute pain via directly activating toll like receptor 4. Mol Pain 2015; 11:10. [PMID: 25868824 PMCID: PMC4363343 DOI: 10.1186/s12990-015-0005-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/10/2015] [Indexed: 01/01/2023] Open
Abstract
Paclitaxel, a powerful anti-neoplastic drug, often causes pathological pain, which significantly reduces the quality of life in patients. Paclitaxel-induced pain includes pain that occurs immediately after paclitaxel treatment (paclitaxel-associated acute pain syndrome, P-APS) and pain that persists for weeks to years after cessation of paclitaxel treatment (paclitaxel induced chronic neuropathic pain). Mechanisms underlying P-APS remain unknown. In this study, we found that paclitaxel causes acute pain in rodents in a dose-dependent manner. The paclitaxel-induced acute pain occurs within 2 hrs after a single intravenous injection of paclitaxel. This is accompanied by low levels of paclitaxel penetrating into the cerebral spinal fluid and spinal dorsal horn. We demonstrated that an intrathecal injection of paclitaxel induces mechanical allodynia in a dose-dependent manner. Paclitaxel causes activation of toll like receptor 4 (TLR4) in the spinal dorsal horn and dorsal root ganglions. Through activating TLR4, paclitaxel increases glutamatergic synaptic activities and reduces glial glutamate transporter activities in the dorsal horn. Activations of TLR4 are necessary in the genesis of paclitaxel-induced acute pain. The cellular and molecular signaling pathways revealed in this study could provide rationales for the development of analgesics and management strategies for P-APS in patients.
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Yan H, Hong P, Jiang M, Li H. MicroRNAs as potential therapeutics for treating spinal cord injury. Neural Regen Res 2015; 7:1352-9. [PMID: 25657667 PMCID: PMC4308808 DOI: 10.3969/j.issn.1673-5374.2012.17.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 05/03/2012] [Indexed: 12/11/2022] Open
Abstract
MicroRNAs are a class of recently discovered, small non-coding RNAs that have been shown to play essential roles in a vast majority of biological processes. Very little is known about the role of microRNAs during spinal cord injury. This review summarizes the changes in expression levels of microRNAs after spinal cord injury. These aberrant changes suggest that microRNAs play an important role in inflammation, oxidative stress, apoptosis, glial scar formation and axonal regeneration. Given their small size and specificity of action, microRNAs could be potential therapeutics for treating spinal cord injury in the future. There are rapidly developing techniques for manipulating microRNA levels in animals; we review different chemical modification and delivery strategies. These may provide platforms for designing efficient microRNA delivery protocols for use in the clinic.
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Affiliation(s)
- Hualin Yan
- West China Developmental & Stem Cell Institute, Department of Obstetric & Gynecologic and Pediatric, Key Laboratory of Obstetric & Gynecologic and Pediatric Diseases and Birth Defects, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, Sichuan Province, China ; West China Medical School, Sichuan University, Chengdu 610041, Sichuan Province, China
| | - Peiwei Hong
- West China Developmental & Stem Cell Institute, Department of Obstetric & Gynecologic and Pediatric, Key Laboratory of Obstetric & Gynecologic and Pediatric Diseases and Birth Defects, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, Sichuan Province, China
| | - Mei Jiang
- West China Developmental & Stem Cell Institute, Department of Obstetric & Gynecologic and Pediatric, Key Laboratory of Obstetric & Gynecologic and Pediatric Diseases and Birth Defects, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, Sichuan Province, China
| | - Hedong Li
- West China Developmental & Stem Cell Institute, Department of Obstetric & Gynecologic and Pediatric, Key Laboratory of Obstetric & Gynecologic and Pediatric Diseases and Birth Defects, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, Sichuan Province, China
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50
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Manček-Keber M, Jerala R. Postulates for validating TLR4 agonists. Eur J Immunol 2015; 45:356-70. [DOI: 10.1002/eji.201444462] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 10/20/2014] [Accepted: 12/01/2014] [Indexed: 02/03/2023]
Affiliation(s)
- Mateja Manček-Keber
- Department of Biotechnology; National Institute of Chemistry; Ljubljana Slovenia
- EN-FIST Centre of Excellence; Ljubljana Slovenia
| | - Roman Jerala
- Department of Biotechnology; National Institute of Chemistry; Ljubljana Slovenia
- EN-FIST Centre of Excellence; Ljubljana Slovenia
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