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Kuan YH, Li FA, Cheng SJ, Chang WP, Shyu BC. Modulation of Thalamocingulate Nociceptive Transmission and Glutamate Secretion by Targeting P2×7 Receptor. THE JOURNAL OF PAIN 2023; 24:1915-1930. [PMID: 37271352 DOI: 10.1016/j.jpain.2023.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 05/12/2023] [Accepted: 05/30/2023] [Indexed: 06/06/2023]
Abstract
The complexity and diversity of pain signaling have led to obstacles for prominent treatments due to mechanisms that are not yet fully understood. Among adenosine triphosphate (ATP) receptors, P2×7 differs in many respects from P2×1-6, it plays a significant role in various inflammatory pain, but whether it plays a role in noninflammatory pain has not been widely discussed. In this study, we utilized major neuropharmacological methods to record the effects of manipulating P2×7 during nociceptive signal transmission in the thalamocingulate circuits. Our results show that regardless of the specific cell type distribution of P2×7 in the central nervous system (CNS), it participates directly in the generated nociceptive transmission, which indicates its apparent functional existence in the major pain transmission path, the thalamocingulate circuits. Activation of P2×7 may facilitate transmission velocity along the thalamocingulate projection as well as neuron firings and synaptic vesicle release in anterior cingulate cortical neurons. Targeting thalamic P2×7 affects glutamate and ATP secretion during nociceptive signal transmission. PERSPECTIVE: The observations in this study provide evidence that the ATP receptor P2×7 presents in the central ascending pain path and plays a modulatory role during nociceptive transmission, which could contribute new insights for many antinociceptive applications.
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Affiliation(s)
- Yung-Hui Kuan
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Fu-An Li
- Proteomics Core Facility, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Sin-Jhong Cheng
- Neuro Circuit Electrophysiology Core Facility, Neuroscience Program, Academia Sinica (NPAS), Taipei, Taiwan
| | - Wei-Peng Chang
- Department of Organismal Biology & Anatomy, University of Chicago, Chicago, Illinois
| | - Bai-Chuang Shyu
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
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2
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Kozlovskiy SA, Pislyagin EA, Menchinskaya ES, Chingizova EA, Sabutski YE, Polonik SG, Likhatskaya GN, Aminin DL. Anti-Inflammatory Activity of 1,4-Naphthoquinones Blocking P2X7 Purinergic Receptors in RAW 264.7 Macrophage Cells. Toxins (Basel) 2023; 15:47. [PMID: 36668867 PMCID: PMC9864473 DOI: 10.3390/toxins15010047] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/20/2022] [Accepted: 12/31/2022] [Indexed: 01/09/2023] Open
Abstract
P2X7 receptors are ligand-gated ion channels activated by ATP and play a significant role in cellular immunity. These receptors are considered as a potential therapeutic target for the treatment of multiple inflammatory diseases. In the present work, using spectrofluorimetry, spectrophotometry, Western blotting and ELISA approaches, the ability of 1,4-naphthoquinone thioglucoside derivatives, compounds U-286 and U-548, to inhibit inflammation induced by ATP/LPS in RAW 264.7 cells via P2X7 receptors was demonstrated. It has been established that the selected compounds were able to inhibit ATP-induced calcium influx and the production of reactive oxygen species, and they also exhibited pronounced antioxidant activity in mouse brain homogenate. In addition, compounds U-286 and U-548 decreased the LPS-induced activity of the COX-2 enzyme, the release of pro-inflammatory cytokines TNF-α and IL-1β in RAW 264.7 cells, and significantly protected macrophage cells against the toxic effects of ATP and LPS. This study highlights the use of 1,4-naphthoquinones as promising purinergic P2X7 receptor antagonists with anti-inflammatory activity. Based on the data obtained, studied synthetic 1,4-NQs can be considered as potential scaffolds for the development of new anti-inflammatory and analgesic drugs.
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Affiliation(s)
| | | | | | | | | | | | | | - Dmitry L. Aminin
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far-Eastern Branch of the Russian Academy of Sciences, Vladivostok 690022, Russia
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Dsouza C, Moussa MS, Mikolajewicz N, Komarova SV. Extracellular ATP and its derivatives provide spatiotemporal guidance for bone adaptation to wide spectrum of physical forces. Bone Rep 2022; 17:101608. [PMID: 35992507 PMCID: PMC9385560 DOI: 10.1016/j.bonr.2022.101608] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/27/2022] [Accepted: 07/29/2022] [Indexed: 11/17/2022] Open
Abstract
ATP is a ubiquitous intracellular molecule critical for cellular bioenergetics. ATP is released in response to mechanical stimulation through vesicular release, small tears in cellular plasma membranes, or when cells are destroyed by traumatic forces. Extracellular ATP is degraded by ecto-ATPases to form ADP and eventually adenosine. ATP, ADP, and adenosine signal through purinergic receptors, including seven P2X ATP-gated cation channels, seven G-protein coupled P2Y receptors responsive to ATP and ADP, and four P1 receptors stimulated by adenosine. The goal of this review is to build a conceptual model of the role of different components of this complex system in coordinating cellular responses that are appropriate to the degree of mechanical stimulation, cell proximity to the location of mechanical injury, and time from the event. We propose that route and amount of ATP release depend on the scale of mechanical forces, ranging from vesicular release of small ATP boluses upon membrane deformation, to leakage of ATP through resealable plasma membrane tears, to spillage of cellular content due to destructive forces. Correspondingly, different P2 receptors responsive to ATP will be activated according to their affinity at the site of mechanical stimulation. ATP is a small molecule that readily diffuses through the environment, bringing the signal to the surrounding cells. ATP is also degraded to ADP which can stimulate a distinct set of P2 receptors. We propose that depending on the magnitude of mechanical forces and distance from the site of their application, ATP/ADP profiles will be different, allowing the relay of information about tissue level injury and proximity. Lastly, ADP is degraded to adenosine acting via its P1 receptors. The presence of large amounts of adenosine without ATP, indicates that an active source of ATP release is no longer present, initiating the transition to the recovery phase. This model consolidates the knowledge regarding the individual components of the purinergic system into a conceptual framework of choreographed responses to physical forces. Cellular bioenergetic molecule ATP is released when cell is mechanically stimulated. ATP release is proportional to the amount of cellular damage. ATP diffusion and transformation to ADP indicates the proximity to the damage. Purinergic receptors form a network choreographing cell response to physical forces. Complete transformation of ATP to adenosine initiates the recovery phase.
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Affiliation(s)
- Chrisanne Dsouza
- Department of Experimental Surgery, McGill University, Montreal, QC H3G 1A4, Canada
- Shriners Hospitals for Children- Canada, Montreal, QC H4A 0A9, Canada
| | - Mahmoud S. Moussa
- Shriners Hospitals for Children- Canada, Montreal, QC H4A 0A9, Canada
- Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, QC H3A 1G1, Canada
| | - Nicholas Mikolajewicz
- Shriners Hospitals for Children- Canada, Montreal, QC H4A 0A9, Canada
- Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, QC H3A 1G1, Canada
| | - Svetlana V. Komarova
- Department of Experimental Surgery, McGill University, Montreal, QC H3G 1A4, Canada
- Shriners Hospitals for Children- Canada, Montreal, QC H4A 0A9, Canada
- Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, QC H3A 1G1, Canada
- Corresponding author.
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Gusso D, Cruz FF, Fritsch PM, da Silva Gobbo MO, Morrone FB, Bonan CD. Pannexin channel 1, P2X7 receptors, and Dimethyl Sulfoxide mediate pain responses in zebrafish. Behav Brain Res 2022; 423:113786. [DOI: 10.1016/j.bbr.2022.113786] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/19/2022] [Accepted: 02/01/2022] [Indexed: 12/15/2022]
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Jiang Y, Ye F, Du Y, Zong Y, Tang Z. P2X7R in Mast Cells is a Potential Target for Salicylic Acid and Aspirin in Treatment of Inflammatory Pain. J Inflamm Res 2021; 14:2913-2931. [PMID: 34239315 PMCID: PMC8259951 DOI: 10.2147/jir.s313348] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 06/04/2021] [Indexed: 12/27/2022] Open
Abstract
Background Mast cells are well known for their role in inflammatory pain. P2X7 receptor (P2X7R) has attracted much attention due to its prominent role in inflammatory diseases. Salicylates are commonly used anti-inflammatory and analgesic drugs. Until now, little has been known about whether P2X7R in mast cells is involved in inflammatory pain and whether it is a potential target for salicylates. Methods First, the expression of P2X receptors in mouse peritoneal mast cells was detected by using RT-PCR, immunofluorescence, calcium imaging and electrophysiological technique. In addition, the functions of P2X receptors, especially P2X7R, in mast cells were studied by using QPCR, ELISA and behavioral tests. Furthermore, P2X7R was used as a target to screen for some anti-inflammatory monomers that could inhibit its activity. At last, the effect of salicylic acid (SA) and aspirin (ASA) on the activity of P2X7R was studied by using calcium imaging, electrophysiological technique, ELISA, real-time PCR, behavioral tests, immunofluorescence and molecular docking. Results We found that P2X1, P2X3, P2X4 and P2X7 receptors were expressed in mouse peritoneal mast cells. The functions of different P2X receptors were various. Activation of P2X7R in mouse mast cells induced the release of inflammatory mediators, such as histamine, IL-1β, and CCL3. In addition, inflammation pain induced by high concentrations of ATP could be alleviated by P2X7R blockers or mast cell defects. Interestingly, SA or ASA could reduce high concentrations of ATP-induced inward current, P2X7R upregulation, mediators release, and inflammatory pain. SA or ASA also inhibited the inward current evoked by P2X7R agonist, BZATP. Molecular docking showed that SA or ASA had affinity for the cytoplasmic GDP-binding region of P2X7R. Conclusion P2X7R in mast cells was involved in inflammation pain by releasing inflammatory mediators, and P2X7R might be a potential target for SA and ASA analgesia.
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Affiliation(s)
- Yucui Jiang
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, People's Republic of China.,School of Chinese Medicine & School of Integrated Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, People's Republic of China
| | - Fan Ye
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, People's Republic of China
| | - Ying Du
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, People's Republic of China
| | - Yingxin Zong
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, People's Republic of China
| | - Zongxiang Tang
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, People's Republic of China
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Brain immune cells characterization in UCMS exposed P2X7 knock-out mouse. Brain Behav Immun 2021; 94:159-174. [PMID: 33609652 DOI: 10.1016/j.bbi.2021.02.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 02/10/2021] [Accepted: 02/11/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Several lines of evidence suggest that neuroinflammation might be a key neurobiological mechanism of depression. In particular, the P2X7 receptor (P2X7R), an ATP-gated ion channel involved in activation of the pro-inflammatory interleukin IL-1β, has been shown to be a potential new pharmacological target in depression. The aim of this study was to explore the impact of unpredictable chronic mild stress (UCMS) on behavioural changes, hippocampal neurogenesis, and cellular characterisation of brain immune cells, in P2X7R Knock-Out (KO) mice. METHODS P2X7R KO and wild-type (WT) mice were subjected to a 6-week UCMS protocol and received a conventional oral antidepressant (15 mg.kg-1 fluoxetine) or water per os. The mice then underwent behavioural tests consisting of the tail suspension test (TST), the elevated plus maze (EPM) test, the open field test, the splash test and the nest building test (week 7). Doublecortin immunostaining (DCX) of brain slices was used to assess neurogenesis in the dentate gyrus. Iba1 and TMEM119 immunostaining was used to characterise brain immune cells, Iba1 as a macrophage marker (including microglial cells) and TMEM119 as a potential specific resident microglial cells marker. RESULTS After a 6-week UCMS exposure, P2X7R KO mice exhibited less deterioration of their coat state, spent a significantly smaller amount of time immobile in the TST and spent a larger amount of time in the open arms of the EPM. As expected, adult ventral hippocampal neurogenesis was significantly decreased by UCMS in WT mice, while P2X7R KO mice maintained ventral hippocampal neurogenesis at similar levels in both control and UCMS conditions. In stress-related brain regions, P2X7R KO mice also exhibited less recruitment of Iba1+/TMEM119+ and Iba1+/TMEM119- cells in the brain. The ratio between these two staining patterns revealed that brain immune cells were mostly composed of Iba1+/TMEM119+ cells (87 to 99%), and this ratio was affected neither by P2X7R genetic depletion nor by antidepressant treatment. DISCUSSION Behavioural patterns, neurogenesis levels and density of brain immune cells in P2X7R KO mice after exposure to UCMS significantly differed from control conditions. Brain immune cells were mostly increased in brain regions known to be sensitive to UCMS exposure in WT but not in P2X7R KO mice. Considering Iba1+/TMEM119- staining might characterize peripheral immune cells, the ratio between Iba1+/TMEM119+ cells and IBA1+/TMEM119- cells, suggests that the rate of peripheral immune cells recruitment may not be modified neither by P2X7R gene expression nor by antidepressant treatment.
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Retrograde Labeling of Different Distribution Features of DRG P2X2 and P2X3 Receptors in a Neuropathic Pain Rat Model. BIOMED RESEARCH INTERNATIONAL 2020; 2020:9861459. [PMID: 32775458 PMCID: PMC7396081 DOI: 10.1155/2020/9861459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/03/2020] [Accepted: 07/08/2020] [Indexed: 12/25/2022]
Abstract
The distributions of P2X subtypes during peripheral neuropathic pain conditions and their differential roles are not fully understood. To explore these characteristics, the lumbosacral dorsal root ganglion (DRG) in the chronic constriction injury (CCI) sciatic nerve rat model was studied. Retrograde trace labeling combined with immunofluorescence technology was applied to analyze the distribution of neuropathic nociceptive P2X1-6 receptors. Our results suggest that Fluoro-Gold (FG) retrograde trace labeling is an efficient method for studying lumbosacral DRG neurons in the CCI rat model, especially when the DRG neurons are divided into small, medium, and large subgroups. We found that neuropathic nociceptive lumbosacral DRG neurons (i.e., FG-positive cells) were significantly increased in medium DRG neurons, while they declined in the large DRG neurons in the CCI group. P2X3 receptors were markedly upregulated in medium while P2X2 receptors were significantly decreased in small FG-positive DRG neurons. There were no significant changes in other P2X receptors (including P2X1, P2X4, P2X5, and P2X6). We anticipate that P2X receptors modulate nociceptive sensitivity primarily through P2X3 subtypes that are upregulated in medium neuropathic nociceptive DRG neurons and/or via the downregulation of P2X2 cells in neuropathic nociceptive small DRG neurons.
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Hu WS, Li SH, Wu QF. Purinergic signaling in inflammatory bowel disease. Shijie Huaren Xiaohua Zazhi 2019; 27:125-130. [DOI: 10.11569/wcjd.v27.i2.125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Inflammatory bowel disease (IBD) is a chronic, relapsing, inflammatory disease of the gut. In recent years, its incidence has continued to rise. So far, the exact cause of IBD is still unknown. Prinergic signaling is widely involved in the body's inflammatory immune response and is closely related to the occurrence of pain. A growing body of evidence indicates that purinergic signaling and its receptor system play an important role in IBD, and are widely involved in the development of IBD, which provides a new idea for its treatment. This article reviews the role of purinergic signaling in IBD.
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Affiliation(s)
- Wei-Shang Hu
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu 610075, Sichuan Province, China
| | - Si-Hui Li
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu 610075, Sichuan Province, China
| | - Qiao-Feng Wu
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu 610075, Sichuan Province, China
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Locke GM, Bernhard SSR, Senge MO. Nonconjugated Hydrocarbons as Rigid-Linear Motifs: Isosteres for Material Sciences and Bioorganic and Medicinal Chemistry. Chemistry 2019; 25:4590-4647. [PMID: 30387906 DOI: 10.1002/chem.201804225] [Citation(s) in RCA: 122] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 10/20/2018] [Indexed: 01/02/2023]
Abstract
Nonconjugated hydrocarbons, like bicyclo[1.1.1]pentane, bicyclo[2.2.2]octane, triptycene, and cubane are a unique class of rigid linkers. Due to their similarity in size and shape they are useful mimics of classic benzene moieties in drugs, so-called bioisosteres. Moreover, they also fulfill an important role in material sciences as linear linkers, in order to arrange various functionalities in a defined spatial manner. In this Review article, recent developments and usages of these special, rectilinear systems are discussed. Furthermore, we focus on covalently linked, nonconjugated linear arrangements and discuss the physical and chemical properties and differences of individual linkers, as well as their application in material and medicinal sciences.
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Affiliation(s)
- Gemma M Locke
- School of Chemistry, SFI Tetrapyrrole Laboratory, Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse Street, Dublin, 2, Ireland
| | - Stefan S R Bernhard
- School of Chemistry, SFI Tetrapyrrole Laboratory, Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse Street, Dublin, 2, Ireland
| | - Mathias O Senge
- School of Chemistry, SFI Tetrapyrrole Laboratory, Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse Street, Dublin, 2, Ireland
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Farooq RK, Tanti A, Ainouche S, Roger S, Belzung C, Camus V. A P2X7 receptor antagonist reverses behavioural alterations, microglial activation and neuroendocrine dysregulation in an unpredictable chronic mild stress (UCMS) model of depression in mice. Psychoneuroendocrinology 2018; 97:120-130. [PMID: 30015007 DOI: 10.1016/j.psyneuen.2018.07.016] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 06/25/2018] [Accepted: 07/08/2018] [Indexed: 12/20/2022]
Abstract
A polymorphism in the P2RX7 gene that encodes for the P2X7 ionotropic ATP-gated receptor (P2X7R) protein has been shown to be associated with an increased risk for developing depressive illnesses. However, the role of P2X7R in depression is still unclear. To better understand the role of P2X7R and its subsequent impact on microglial activation, we compared the effect of the P2X7R antagonist Brilliant Blue G (BBG) with that of fluoxetine in an unpredictable chronic mild stress (UCMS) model of depression in mice. Our results indicate that BBG (50 mg/kg body weight in 0.9% NaCl, 10 ml/kg/day) successfully reversed the degradation of coat states and nest-building scores induced by exposure to UCMS, similar to the conventional antidepressant fluoxetine (15 mg/kg body weight in 0.9% NaCl, 10 ml/kg/day). BBG also reversed the UCMS-induced microglial activation in cortical and hippocampal regions and the basal nuclei of mouse brains and corrected the UCMS-induced hypothalamo-pituitary-adrenal (HPA) axis dysregulation. In contrast to fluoxetine, however, BBG treatment did not increase the density of doublecortin-positive cells in the dentate gyrus, indicating that BBG had no impact on hippocampal neurogenesis. These results suggest that P2X7R is involved in recovery from depressive-like states caused by exposure to UCMS in a mechanism that involves restoration of the HPA axis but not hippocampal neurogenesis. These results add to the evidence that P2X7R antagonist agents may have potential value in the pharmacological management of depression.
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Affiliation(s)
- Rai Khalid Farooq
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France; Inserm U1069, Tours, France.
| | - Arnaud Tanti
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France; Inserm U1069, Tours, France
| | - Samia Ainouche
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France; Inserm U1069, Tours, France
| | | | - Catherine Belzung
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France; Inserm U1069, Tours, France
| | - Vincent Camus
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France; Inserm U1069, Tours, France; CHRU de Tours, Clinique Psychiatrique Universitaire, Tours, France
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Li P, Zhang Q, Xiao Z, Yu S, Yan Y, Qin Y. Activation of the P2X 7 receptor in midbrain periaqueductal gray participates in the analgesic effect of tramadol in bone cancer pain rats. Mol Pain 2018; 14:1744806918803039. [PMID: 30198382 PMCID: PMC6176534 DOI: 10.1177/1744806918803039] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Background Cancer pain is a well-known serious complication in metastatic or terminal cancer patients. Current pain management remains unsatisfactory. The activation of spinal and supraspinal P2X7 receptors plays a crucial role in the induction and maintenance mechanisms of various kinds of acute or chronic pain. The midbrain periaqueductal gray is a vital supraspinal site of the endogenous descending pain-modulating system. Tramadol is a synthetic, centrally acting analgesic agent that exhibits considerable efficacy in clinically relieving pain. The purpose of this study was to determine whether the activation of P2X7 receptor in the ventrolateral region of the periaqueductal gray (vlPAG) participates in the analgesic mechanisms of tramadol on bone cancer pain in rats. The bone cancer pain rat model was established by intratibial cell inoculation of SHZ-88 mammary gland carcinoma cells. The analgesic effects of different doses of tramadol (10, 20, and 40 mg/kg) were assessed by measuring the mechanical withdrawal threshold and thermal withdrawal latency values in rats by using an electronic von Frey anesthesiometer and radiant heat stimulation, respectively. Alterations in the number of P2X7 receptor-positive cells and P2X7 protein levels in vlPAG were separately detected by using immunohistochemistry and Western blot assay. The effect of intra-vlPAG injection of A-740003 (100 nmol), a selective competitive P2X7 receptor antagonist, on the analgesic effect of tramadol was also observed. Results The expression of P2X7 receptor in the vlPAG on bone cancer pain rats was mildly elevated, and the tramadol (10, 20, and 40 mg/kg) dose dependently relieved pain-related behaviors in bone cancer pain rats and further upregulated the expression of P2X7 receptor in the vlPAG. The intra-vlPAG injection of A-740003 pretreatment partly but significantly antagonized the analgesic effect of tramadol on bone cancer pain rats. Conclusions The injection of tramadol can dose dependently elicit analgesic effect on bone cancer pain rats by promoting the expression of the P2X7 receptor in vlPAG.
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Affiliation(s)
- Pengtao Li
- 1 Graduate School, Zunyi Medical University, Zunyi, Guizhou, China
| | - Quan Zhang
- 2 Key Laboratory of Brain Science, Zunyi Medical University, Zunyi, Guizhou, China.,3 Research Center for Medicine and Biology, Zunyi Medical University, Zunyi, Guizhou, China
| | - Zhi Xiao
- 2 Key Laboratory of Brain Science, Zunyi Medical University, Zunyi, Guizhou, China.,3 Research Center for Medicine and Biology, Zunyi Medical University, Zunyi, Guizhou, China
| | - Shouyang Yu
- 2 Key Laboratory of Brain Science, Zunyi Medical University, Zunyi, Guizhou, China
| | - Yan Yan
- 2 Key Laboratory of Brain Science, Zunyi Medical University, Zunyi, Guizhou, China.,3 Research Center for Medicine and Biology, Zunyi Medical University, Zunyi, Guizhou, China
| | - Ying Qin
- 3 Research Center for Medicine and Biology, Zunyi Medical University, Zunyi, Guizhou, China
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12
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Guo SW, Groothuis PG. Is it time for a paradigm shift in drug research and development in endometriosis/adenomyosis? Hum Reprod Update 2018; 24:577-598. [DOI: 10.1093/humupd/dmy020] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/21/2018] [Indexed: 12/19/2022] Open
Affiliation(s)
- Sun-Wei Guo
- Shanghai OB/GYN Hospital, Fudan University, Shanghai, China
- Shanghai Key Laboratory of Female Reproductive Endocrine-Related Diseases, Fudan University, Shanghai, China
| | - Patrick G Groothuis
- Principal Scientist Pharmacology, Preclinical Department, Synthon Biopharmaceuticals bv, Nijmegen, The Netherlands
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Site-Specific Regulation of P2X7 Receptor Function in Microglia Gates Morphine Analgesic Tolerance. J Neurosci 2017; 37:10154-10172. [PMID: 28924009 DOI: 10.1523/jneurosci.0852-17.2017] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 09/03/2017] [Indexed: 01/12/2023] Open
Abstract
Tolerance to the analgesic effects of opioids is a major problem in chronic pain management. Microglia are implicated in opioid tolerance, but the core mechanisms regulating their response to opioids remain obscure. By selectively ablating microglia in the spinal cord using a saporin-conjugated antibody to Mac1, we demonstrate a causal role for microglia in the development, but not maintenance, of morphine tolerance in male rats. Increased P2X7 receptor (P2X7R) activity is a cardinal feature of microglial activation, and in this study we found that morphine potentiates P2X7R-mediated Ca2+ responses in resident spinal microglia acutely isolated from morphine tolerant rats. The increased P2X7R function was blocked in cultured microglia by PP2, a Src family protein tyrosine kinase inhibitor. We identified Src family kinase activation mediated by μ-receptors as a key mechanistic step required for morphine potentiation of P2X7R function. Furthermore, we show by site-directed mutagenesis that tyrosine (Y382-384) within the P2X7R C-terminus is differentially modulated by repeated morphine treatment and has no bearing on normal P2X7R function. Intrathecal administration of a palmitoylated peptide corresponding to the Y382-384 site suppressed morphine-induced microglial reactivity and preserved the antinociceptive effects of morphine in male rats. Thus, site-specific regulation of P2X7R function mediated by Y382-384 is a novel cellular determinant of the microglial response to morphine that critically underlies the development of morphine analgesic tolerance.SIGNIFICANCE STATEMENT Controlling pain is one of the most difficult challenges in medicine and its management is a requirement of a large diversity of illnesses. Although morphine and other opioids offer dramatic and impressive relief of pain, their impact is truncated by loss of efficacy (analgesic tolerance). Understanding why this occurs and how to prevent it are of critical importance in improving pain therapies. We uncovered a novel site (Y382-384) within the P2X7 receptor that can be targeted to blunt the development of morphine analgesic tolerance, without affecting normal P2X7 receptor function. Our findings provide a critical missing mechanistic piece, site-specific modulation by Y382-384, that unifies P2X7R function to the activation of spinal microglia and the development of morphine tolerance.
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Neuronal P2X7 receptor-induced reactive oxygen species production contributes to nociceptive behavior in mice. Sci Rep 2017; 7:3539. [PMID: 28615626 PMCID: PMC5471238 DOI: 10.1038/s41598-017-03813-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 05/03/2017] [Indexed: 11/27/2022] Open
Abstract
ATP can activate a variety of pathways through P2 purinoreceptors, leading to neuroprotection and pathology in the CNS. Among all P2X receptors, the P2X7 receptor (P2X7R) is a well-defined therapeutic target for inflammatory and neuropathic pain. Activation of P2X7R can generate reactive oxygen species (ROS) in macrophages and microglia. However, the role of ROS in P2X7R–induced pain remains unexplored. Here, we investigated the downstream effects of neuronal P2X7R activation in the spinal cord. We found that ATP induces ROS production in spinal cord dorsal horn neurons, an effect eliminated by ROS scavenger N-tert-butyl-α-phenylnitrone (PBN) and P2X7R antagonist A438079. A similar effect was observed with a P2X7R agonist, BzATP, and was attenuated by a NADPH oxidase inhibitor apocynin. Intrathecal administration of BzATP resulted in ROS production in the spinal cord and oxidative DNA damage in dorsal horn neurons. BzATP also induced robust biphasic spontaneous nociceptive behavior. Pre-treatment with A438079 abolished all BzATP-induced nociceptive behaviors, while ROS scavengers dose-dependently attenuated the secondary response. Here, we provide evidence that neuronal P2X7R activation leads to ROS production and subsequent nociceptive pain in mice. Together, the data indicate that P2X7R-induced ROS play a critical role in the P2X7R signaling pathway of the CNS.
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Pettengill MA, Abdul-Sater A, Coutinho-Silva R, Ojcius DM. Danger signals, inflammasomes, and the intricate intracellular lives of chlamydiae. Biomed J 2016; 39:306-315. [PMID: 27884377 PMCID: PMC6138786 DOI: 10.1016/j.bj.2016.07.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 07/13/2016] [Indexed: 12/20/2022] Open
Abstract
Chlamydiae are obligate intracellular bacterial pathogens, and as such are sensitive to alterations in the cellular physiology of their hosts. Chlamydial infections often cause pathologic consequences due to prolonged localized inflammation. Considerable advances have been made in the last few years regarding our understanding of how two key inflammation-associated signaling pathways influence the biology of Chlamydia infections: inflammation regulating purinergic signaling pathways significantly impact intracellular chlamydial development, and inflammasome activation modulates both chlamydial growth and infection mediated pro-inflammatory cytokine production. We review here elements of both pathways, presenting the latest developments contributing to our understanding of how chlamydial infections are influenced by inflammasomes and purinergic signaling.
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Affiliation(s)
| | - Ali Abdul-Sater
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
| | - Robson Coutinho-Silva
- Laboratory of Immunophysiology, Carlos Chagas Filho Biophysics Institute of the Federal University of Rio de Janeiro, Brazil
| | - David M Ojcius
- Laboratory of Immunophysiology, Carlos Chagas Filho Biophysics Institute of the Federal University of Rio de Janeiro, Brazil; Department of Biomedical Sciences, University of the Pacific, Arthur Dugoni School of Dentistry, San Francisco, USA.
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16
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Peng F, Xiong L, Tang H, Peng C, Chen J. Regulation of epithelial-mesenchymal transition through microRNAs: clinical and biological significance of microRNAs in breast cancer. Tumour Biol 2016; 37:14463-14477. [DOI: 10.1007/s13277-016-5334-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 09/06/2016] [Indexed: 12/16/2022] Open
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17
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Sakr M, Takino T, Sabit H, Nakada M, Li Z, Sato H. miR-150-5p and miR-133a suppress glioma cell proliferation and migration through targeting membrane-type-1 matrix metalloproteinase. Gene 2016; 587:155-62. [DOI: 10.1016/j.gene.2016.04.058] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Revised: 04/18/2016] [Accepted: 04/28/2016] [Indexed: 01/12/2023]
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18
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Kuan YH, Shyu BC. Nociceptive transmission and modulation via P2X receptors in central pain syndrome. Mol Brain 2016; 9:58. [PMID: 27230068 PMCID: PMC4880968 DOI: 10.1186/s13041-016-0240-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 05/17/2016] [Indexed: 01/03/2023] Open
Abstract
Painful sensations are some of the most frequent complaints of patients who are admitted to local medical clinics. Persistent pain varies according to its causes, often resulting from local tissue damage or inflammation. Central somatosensory pathway lesions that are not adequately relieved can consequently cause central pain syndrome or central neuropathic pain. Research on the molecular mechanisms that underlie this pathogenesis is important for treating such pain. To date, evidence suggests the involvement of ion channels, including adenosine triphosphate (ATP)-gated cation channel P2X receptors, in central nervous system pain transmission and persistent modulation upon and following the occurrence of neuropathic pain. Several P2X receptor subtypes, including P2X2, P2X3, P2X4, and P2X7, have been shown to play diverse roles in the pathogenesis of central pain including the mediation of fast transmission in the peripheral nervous system and modulation of neuronal activity in the central nervous system. This review article highlights the role of the P2X family of ATP receptors in the pathogenesis of central neuropathic pain and pain transmission. We discuss basic research that may be translated to clinical application, suggesting that P2X receptors may be treatment targets for central pain syndrome.
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Affiliation(s)
- Yung-Hui Kuan
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan, Republic of China
| | - Bai-Chuang Shyu
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan, Republic of China.
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19
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Rawson S, Davies S, Lippiat JD, Muench SP. The changing landscape of membrane protein structural biology through developments in electron microscopy. Mol Membr Biol 2016; 33:12-22. [PMID: 27608730 PMCID: PMC5206964 DOI: 10.1080/09687688.2016.1221533] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 07/14/2016] [Accepted: 07/19/2016] [Indexed: 11/30/2022]
Abstract
Membrane proteins are ubiquitous in biology and are key targets for therapeutic development. Despite this, our structural understanding has lagged behind that of their soluble counterparts. This review provides an overview of this important field, focusing in particular on the recent resurgence of electron microscopy (EM) and the increasing role it has to play in the structural studies of membrane proteins, and illustrating this through several case studies. In addition, we examine some of the challenges remaining in structural determination, and what steps are underway to enhance our knowledge of these enigmatic proteins.
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Affiliation(s)
- Shaun Rawson
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds,
Leeds,
UK
| | - Simon Davies
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds,
Leeds,
UK
| | - Jonathan D. Lippiat
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds,
Leeds,
UK
| | - Stephen P. Muench
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds,
Leeds,
UK
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20
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Cai Z, Liu J, Bian H, Cai J, Zhu G. Suppression of P2X7/NF-κB pathways by Schisandrin B contributes to attenuation of lipopolysaccharide-induced inflammatory responses in acute lung injury. Arch Pharm Res 2016; 39:499-507. [PMID: 26832323 DOI: 10.1007/s12272-016-0713-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 01/26/2016] [Indexed: 10/22/2022]
Abstract
The aim of the present study was to assess the effects and mechanisms of Schisandrin B (SchB) on lipopolysaccharide (LPS)-induced acute lung injury (ALI). ALI was induced in mice by intratracheal instillation of LPS (1 mg/kg), and SchB (25, 50, and 75 mg/kg) was injected 1 h before LPS challenge by gavage. After 12 h, bronchoalveolar lavage fluid (BALF) samples and lung tissues were collected. Histological studies demonstrated that SchB attenuated LPS-induced interstitial edema, hemorrhage, and infiltration of neutrophils in the lung tissue. SchB pretreatment at doses of 25, 50, and 75 mg/kg was shown to reduce LPS-induced lung wet-to-dry weight ratio and lung myeloperoxidase activity. In addition, pretreatment with SchB lowered the number of inflammatory cells and pro-inflammatory cytokines including tumor necrosis factor-α, interleukin-1β, and interleukin-6 in BALF. The mRNA and protein expression levels of nuclear factor kappa B (NF-κB) signaling-related molecules activated by P2X7 were investigated to determine the molecular mechanism of SchB. The findings presented here suggest that the protective mechanism of SchB may be attributed partly to the decreased production of pro-inflammatory cytokines through the inhibition of P2X7/NF-κB activation.
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Affiliation(s)
- Zhiyong Cai
- Newborn Department, Yancheng Maternity and Child Health Care Hospital, Yancheng, 224000, Jiangsu Province, China
| | - Jindi Liu
- Nursing Department, Yancheng Maternity and Child Health Care Hospital, Yancheng, 224000, Jiangsu Province, China
| | - Hongliang Bian
- Newborn Department, Yancheng Maternity and Child Health Care Hospital, Yancheng, 224000, Jiangsu Province, China.
| | - Jinlan Cai
- Newborn Department, Yancheng Maternity and Child Health Care Hospital, Yancheng, 224000, Jiangsu Province, China
| | - Gendi Zhu
- Newborn Department, Yancheng Maternity and Child Health Care Hospital, Yancheng, 224000, Jiangsu Province, China
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21
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Burnstock G. P2X ion channel receptors and inflammation. Purinergic Signal 2016; 12:59-67. [PMID: 26739702 DOI: 10.1007/s11302-015-9493-0] [Citation(s) in RCA: 159] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 12/23/2015] [Indexed: 12/20/2022] Open
Abstract
Neuroinflammation limits tissue damage in response to pathogens or injury and promotes repair. There are two stages of inflammation, initiation and resolution. P2X receptors are gaining attention in relation to immunology and inflammation. The P2X7 receptor in particular appears to be an essential immunomodulatory receptor, although P2X1 and P2X4 receptors also appear to be involved. ATP released from damaged or infected cells causes inflammation by release of inflammatory cytokines via P2X7 receptors and acts as a danger signal by occupying upregulated P2X receptors on immune cells to increase immune responses. The purinergic involvement in inflammation is being explored for the development of novel therapeutic strategies.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK. .,Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, Australia.
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22
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Vieira FS, Nanini HF, Takiya CM, Coutinho-Silva R. P2X7 receptor knockout prevents streptozotocin-induced type 1 diabetes in mice. Mol Cell Endocrinol 2016; 419:148-57. [PMID: 26483196 DOI: 10.1016/j.mce.2015.10.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Revised: 09/15/2015] [Accepted: 10/12/2015] [Indexed: 12/20/2022]
Abstract
Type 1 diabetes (T1D) is caused by autoimmune destruction of islet of Langerhans β-cells. P2X7 receptors (P2X7R) modulate proinflammatory immune responses by binding extracellular ATP, a classic 'danger signal'. Here, we evaluated whether the P2X7R has a role in T1D development. P2X7(-/-) mice are resistant to TD1 induction by streptozotocin (STZ) treatment, with no increase in blood glucose, decrease in insulin-positive cells, and pancreatic islet reduction, compared to WT (C57BL/6) mice. Also, the levels of proinflammatory mediators (IL-1β, IFN-γ and NO) did not increase after STZ treatment in P2X7(-/-) animals, with reduced infiltration of CD4(+), CD8(+), B220(+), CD11b(+) and CD11c(+) cells in the pancreatic lymph nodes. Treatment with a P2X7 antagonist mimicked the effect of P2X7 knockout, preventing STZ-induced diabetes. Our results show that the absence of the P2X7R provides resistance in the induction of diabetes in this model, and suggest that therapy targeting the P2X7R may be useful against clinical T1D.
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Affiliation(s)
- Flávia Sarmento Vieira
- Laboratório de Imunofisiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Hayandra Ferreira Nanini
- Laboratório de Imunofisiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Christina Maeda Takiya
- Laboratório de Patologia Clínica do Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Instituto de Biofísica Carlos Chagas Filho, CCS, Rio de Janeiro, RJ, Brazil
| | - Robson Coutinho-Silva
- Laboratório de Imunofisiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
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23
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Abstract
There is a brief introductory summary of purinergic signaling involving ATP storage, release, and ectoenzymatic breakdown, and the current classification of receptor subtypes for purines and pyrimidines. The review then describes purinergic mechanosensory transduction involved in visceral, cutaneous, and musculoskeletal nociception and on the roles played by receptor subtypes in neuropathic and inflammatory pain. Multiple purinoceptor subtypes are involved in pain pathways both as an initiator and modulator. Activation of homomeric P2X3 receptors contributes to acute nociception and activation of heteromeric P2X2/3 receptors appears to modulate longer-lasting nociceptive sensitivity associated with nerve injury or chronic inflammation. In neuropathic pain activation of P2X4, P2X7, and P2Y12 receptors on microglia may serve to maintain nociceptive sensitivity through complex neural-glial cell interactions and antagonists to these receptors reduce neuropathic pain. Potential therapeutic approaches involving purinergic mechanisms will be discussed.
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24
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Kwak SH, Lee WG, Lee YJ, Lee SD, Kim YC, Ko H. Discovery of novel purine-based heterocyclic P2X7 receptor antagonists. Bioorg Chem 2015; 61:58-65. [DOI: 10.1016/j.bioorg.2015.06.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 06/15/2015] [Accepted: 06/16/2015] [Indexed: 11/30/2022]
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25
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Jeske NA. Peripheral scaffolding and signaling pathways in inflammatory pain. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 131:31-52. [PMID: 25744669 DOI: 10.1016/bs.pmbts.2014.11.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Peripheral injury precipitates the release and accumulation of extracellular molecules at the site of injury. Although these molecules exist in various forms, they activate specific receptor classes expressed on primary afferent neurons to mediate cellular and behavioral responses to both nonpainful and painful stimuli. These inflammatory mediators and subsequent receptor-mediated effects exist to warn an organism of future injury, thereby resulting in protection and rehabilitation of the wounded tissue. In this chapter, inflammatory mediators, their target receptor classes, and downstream signaling pathways are identified and discussed within the context of inflammatory hyperalgesia. Furthermore, scaffolding mechanisms that exist to support inflammatory signaling in peripheral afferent neuronal tissues specifically are identified and discussed. Together, the mediators, pathways, and scaffolding mechanisms involved in inflammatory hyperalgesia provide a unique knowledge point from which new therapeutic targets can be understood.
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Affiliation(s)
- Nathaniel A Jeske
- Department of Oral and Maxillofacial Surgery, UT Health Science Center, San Antonio, Texas, USA.
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26
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Ide S, Nishizawa D, Fukuda KI, Kasai S, Hasegawa J, Hayashida M, Minami M, Ikeda K. Haplotypes of P2RX7 gene polymorphisms are associated with both cold pain sensitivity and analgesic effect of fentanyl. Mol Pain 2014; 10:75. [PMID: 25472448 PMCID: PMC4265416 DOI: 10.1186/1744-8069-10-75] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 11/18/2014] [Indexed: 12/12/2022] Open
Abstract
Background The P2X7 receptor is a member of the P2X family of adenosine 5′-triphosphate-gated cation channels. Several recent studies have demonstrated that this receptor is involved in mechanisms related to pain and inflammation. However, unknown is whether polymorphisms of the P2RX7 gene that encodes the human P2X7 receptor influence pain sensitivity and analgesic effects of opioids. The P2RX7 gene is known to be highly polymorphic. Thus, the present study examined associations between fentanyl sensitivity and polymorphisms in the P2RX7 gene in 355 Japanese patients who underwent painful orofacial cosmetic surgery. Results We first conducted linkage disequilibrium (LD) analyses for 55 reported single-nucleotide polymorphisms (SNPs) in the region within and around the P2RX7 gene using genomic samples from 100 patients. In our samples, 42 SNPs were polymorphic, and a total of five LD blocks with six Tag SNPs (rs2708092, rs1180012, rs1718125, rs208293, rs1718136, and rs7132846) were observed. Thus, we further analyzed associations between genotypes/haplotypes of these Tag SNPs and clinical data using a total of 355 samples. In the genotype-based association study, only the rs1718125 G > A SNP tended to be associated with higher pain scores on a visual analog scale 24 h after surgery (VAS24). The haplotype-based association study showed that subjects with homozygous haplotype No.3 (GTAAAC; estimated frequency: 15.0%) exhibited significantly higher cold pain sensitivity and lower analgesic effects of fentanyl for acute cold pain in the cold pressor test. Conversely, subjects who carried haplotype No.1 (ACGGAC; estimated frequency: 24.5%) tended to exhibit lower cold pain sensitivity and higher analgesic effects of fentanyl. Furthermore, subjects with homozygous haplotype No.2 (GCGGAC; estimated frequency: 22.9%) exhibited significantly lower VAS24 scores. Conclusions Cold pain sensitivity and analgesic effects of fentanyl were related to the SNP and haplotypes of the P2RX7 gene. The patients with the rs1718125 G>A SNP tended to show higher VAS24 scores. Moreover, the combination of polymorphisms from the 5′-flanking region to exon 5 recessively affected cold pain sensitivity and analgesic effects of opioids for acute cold pain. The present findings shed light on the involvement of P2RX7 gene polymorphisms in naive cold pain sensitivity and analgesic effects of fentanyl. Electronic supplementary material The online version of this article (doi:10.1186/1744-8069-10-75) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | | | - Kazutaka Ikeda
- Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
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27
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Ashraf W, Manzoor S, Ashraf J, Ahmed QL, Khalid M, Tariq M, Imran M, Aziz H. Transcript analysis of P2X receptors in PBMCs of chronic HCV patients: an insight into antiviral treatment response and HCV-induced pathogenesis. Viral Immunol 2014; 26:343-50. [PMID: 24116708 DOI: 10.1089/vim.2013.0044] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND After invasion of hepatocytes and immune cells, hepatitis C virus has the ability to escape from the host immune system, leading to the progression of disease into chronic infection with associated liver morbidities. Adenosine 5'triphosphate (ATP) is released in most of the pathological events from the affected cells and acts as a signaling molecule by binding to P2X receptors expressed on the host's immune cells and activates the immune system for pro-inflammatory response. Therefore, the present study was designed to analyze the transcript expression of the ionotropic purinergic P2X receptors on peripheral blood mononuclear cells (PBMCs) of chronic HCV patients to have study the immune responses mediated by P2X receptors in chronic HCV infections. METHODS PBMCs were isolated from the collected blood samples. Transcript analysis of P2X receptors in PBMCs was done. The identity of amplified product was confirmed by sequencing PCR, while the quantification of the transcript expression was done by real time PCR. The relative expression of the P2X receptors was analyzed by unpaired Student's t test using GraphPad Prims 5 software. RESULTS We found that out of seven isoforms of P2X receptors, P2X1, P2X4, P2X5, and P2X7 receptors are expressed on the PBMCs. P2X1 and P2X7 are significantly upregulated in treatment-naïve chronic HCV patients by 2.2- and 2.5-fold, respectively. However, only P2X7 expression is found increased by 2.7-fold in patients achieving sustained virological response (SVR) after antiviral treatment compared to healthy controls. The expression of P2X receptors remained unaltered in chronic HCV patients not responding to the treatment. CONCLUSION The present study confirms the significant involvement of P2X receptors in the immune responses mediated by the PBMCs in the chronic HCV infection, which should be further investigated to devise strategies to augment the immune system against this chronic viral disease.
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Affiliation(s)
- Waseem Ashraf
- 1 Atta ur Rahman School of Applied Bio-Sciences, National University of Sciences & Technology, Islamabad
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Burow P, Klapperstück M, Markwardt F. Activation of ATP secretion via volume-regulated anion channels by sphingosine-1-phosphate in RAW macrophages. Pflugers Arch 2014; 467:1215-26. [PMID: 24965069 DOI: 10.1007/s00424-014-1561-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 06/17/2014] [Indexed: 12/13/2022]
Abstract
We report the activation of outwardly rectifying anion currents by sphingosine-1-phosphate (S1P) in the murine macrophage cell line RAW 264.7. The S1P-induced current is mainly carried by anions, because the reversal potential of the current was shifted by replacement of extracellular Cl(-) by glutamate(-) but not when extracellular Na(+) was substituted by Tris(+). The inhibition of the current by hypertonic extracellular or hypotonic intracellular solution as well as the inhibitory effects of NPPB, tamoxifen, and glibenclamide indicates that the anion current is mediated by volume-regulated anion channels (VRAC). The S1P effect was blocked by intracellular GDPβS and W123, which points to signaling via the S1P receptor 1 (S1PR1) and G proteins. As cytochalasin D diminished the action of S1P, we conclude that the actin cytoskeleton is involved in the stimulation of VRAC. S1P and hypotonic extracellular solution induced secretion of ATP from the macrophages, which in both cases was blocked in a similar way by typical VRAC blockers. We suppose that the S1P-induced ATP secretion in macrophages via activation of VRAC constitutes a functional link between sphingolipid and purinergic signaling in essential processes such as inflammation and migration of leukocytes as well as phagocytosis and the killing of intracellular bacteria.
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Affiliation(s)
- Philipp Burow
- Julius Bernstein Institute for Physiology, Martin Luther University Halle, Magdeburger Str. 6, 06097, Halle/Saale, Germany
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29
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Ficker C, Rozmer K, Kató E, Andó RD, Schumann L, Krügel U, Franke H, Sperlágh B, Riedel T, Illes P. Astrocyte-neuron interaction in the substantia gelatinosa of the spinal cord dorsal horn via P2X7 receptor-mediated release of glutamate and reactive oxygen species. Glia 2014; 62:1671-86. [PMID: 24895290 DOI: 10.1002/glia.22707] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 05/23/2014] [Accepted: 05/23/2014] [Indexed: 12/14/2022]
Abstract
The substantia gelatinosa (SG) of the spinal cord processes incoming painful information to ascending projection neurons. Whole-cell patch clamp recordings from SG spinal cord slices documented that in a low Ca(2+) /no Mg(2+) (low X(2+) ) external medium adenosine triphosphate (ATP)/dibenzoyl-ATP, Bz-ATP) caused inward current responses, much larger in amplitude than those recorded in a normal X(2+) -containing bath medium. The effect of Bz-ATP was antagonized by the selective P2X7 receptor antagonist A-438079. Neuronal, but not astrocytic Bz-ATP currents were strongly inhibited by a combination of the ionotropic glutamate receptor antagonists AP-5 and CNQX. In fact, all neurons and some astrocytes responded to NMDA, AMPA, and muscimol with inward current, demonstrating the presence of the respective receptors. The reactive oxygen species H2 O2 potentiated the effect of Bz-ATP at neurons but not at astrocytes. Hippocampal CA1 neurons exhibited a behavior similar to, but not identical with SG neurons. Although a combination of AP-5 and CNQX almost abolished the effect of Bz-ATP, H2 O2 was inactive. A Bz-ATP-dependent and A-438079-antagonizable reactive oxygen species production in SG slices was proven by a microelectrode biosensor. Immunohistochemical investigations showed the colocalization of P2X7-immunoreactivity with microglial (Iba1), but not astrocytic (GFAP, S100β) or neuronal (MAP2) markers in the SG. It is concluded that SG astrocytes possess P2X7 receptors; their activation leads to the release of glutamate, which via NMDA- and AMPA receptor stimulation induces cationic current in the neighboring neurons. P2X7 receptors have a very low density under resting conditions but become functionally upregulated under pathological conditions.
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Affiliation(s)
- Christoph Ficker
- Rudolf Boehm Institute for Pharmacology und Toxicology, University of Leipzig, Leipzig, Germany
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30
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Bourinet E, Altier C, Hildebrand ME, Trang T, Salter MW, Zamponi GW. Calcium-permeable ion channels in pain signaling. Physiol Rev 2014; 94:81-140. [PMID: 24382884 DOI: 10.1152/physrev.00023.2013] [Citation(s) in RCA: 221] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The detection and processing of painful stimuli in afferent sensory neurons is critically dependent on a wide range of different types of voltage- and ligand-gated ion channels, including sodium, calcium, and TRP channels, to name a few. The functions of these channels include the detection of mechanical and chemical insults, the generation of action potentials and regulation of neuronal firing patterns, the initiation of neurotransmitter release at dorsal horn synapses, and the ensuing activation of spinal cord neurons that project to pain centers in the brain. Long-term changes in ion channel expression and function are thought to contribute to chronic pain states. Many of the channels involved in the afferent pain pathway are permeable to calcium ions, suggesting a role in cell signaling beyond the mere generation of electrical activity. In this article, we provide a broad overview of different calcium-permeable ion channels in the afferent pain pathway and their role in pain pathophysiology.
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31
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Huang S, Chen Y, Wu W, Ouyang N, Chen J, Li H, Liu X, Su F, Lin L, Yao Y. miR-150 promotes human breast cancer growth and malignant behavior by targeting the pro-apoptotic purinergic P2X7 receptor. PLoS One 2013; 8:e80707. [PMID: 24312495 PMCID: PMC3846619 DOI: 10.1371/journal.pone.0080707] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 10/06/2013] [Indexed: 11/18/2022] Open
Abstract
The P2X7 receptor regulates cell growth through mediation of apoptosis. Low level expression of P2X7 has been linked to cancer development because tumor cells harboring a defective P2X7 mechanism can escape P2X7 pro-apoptotic control. microRNAs (miRNAs) function as negative regulators of post-transcriptional gene expression, playing major roles in cellular differentiation, proliferation, and metastasis. In this study, we found that miR-150 was over-expressed in breast cancer cell lines and tissues. In these breast cancer cell lines, blocking the action of miR-150 with inhibitors leads to cell death, while ectopic expression of the miR-150 results in increased cell proliferation. We deploy a microRNA sponge strategy to inhibit miR-150 in vitro, and the result demonstrates that the 3′-untranslated region (3′UTR) of P2X7 receptor contains a highly conserved miR-150-binding motif and its direct interaction with miR-150 down-regulates endogenous P2X7 protein levels. Furthermore, our findings demonstrate that miR-150 over-expression promotes growth, clonogenicity and reduces apoptosis in breast cancer cells. Meanwhile, these findings can be decapitated in nude mice with breast cancer xenografts. Finally, these observations strengthen our working hypothesis that up-regulation of miR-150 in breast cancer is inversely associated with P2X7 receptor expression level. Together, these findings establish miR-150 as a novel regulator of P2X7 and a potential therapeutic target for breast cancer.
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Affiliation(s)
- Songyin Huang
- Department of Laboratory, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Yongsong Chen
- Department of Endocrinology, The First Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong, China
| | - Wei Wu
- Breast Tumor Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Nengyong Ouyang
- Department of Gynaecology and Obstetrics, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Jianing Chen
- Breast Tumor Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Hongyu Li
- Department of Laboratory, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Xiaoqiang Liu
- Department of Laboratory, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Fengxi Su
- Breast Tumor Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Ling Lin
- Department of Rheumatology, The First Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong, China
- * E-mail: (LL); (YDY)
| | - Yandan Yao
- Breast Tumor Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China
- * E-mail: (LL); (YDY)
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32
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Burnstock G. Introduction and perspective, historical note. Front Cell Neurosci 2013; 7:227. [PMID: 24312014 PMCID: PMC3836022 DOI: 10.3389/fncel.2013.00227] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 11/04/2013] [Indexed: 12/11/2022] Open
Abstract
P2 nucleotide receptors were proposed to consist of two subfamilies based on pharmacology in 1985, named P2X and P2Y receptors. Later, this was confirmed following cloning of the receptors for nucleotides and studies of transduction mechanisms in the early 1990s. P2X receptors are ion channels and seven subtypes are recognized that form trimeric homomultimers or heteromultimers. P2X receptors are involved in neuromuscular and synaptic neurotransmission and neuromodulation. They are also expressed on many types of non-neuronal cells to mediate smooth muscle contraction, secretion, and immune modulation. The emphasis in this review will be on the pathophysiology of P2X receptors and therapeutic potential of P2X receptor agonists and antagonists for neurodegenerative and inflammatory disorders, visceral and neuropathic pain, irritable bowel syndrome, diabetes, kidney failure, bladder incontinence and cancer, as well as disorders if the special senses, airways, skin, cardiovascular, and musculoskeletal systems.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical SchoolLondon, UK
- Department of Pharmacology, The University of MelbourneMelbourne, VIC, Australia
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Loss of P2X7 nucleotide receptor function leads to abnormal fat distribution in mice. Purinergic Signal 2013; 10:291-304. [PMID: 24222214 DOI: 10.1007/s11302-013-9388-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 09/10/2013] [Indexed: 12/26/2022] Open
Abstract
The P2X7 receptor is an ATP-gated cation channel expressed by a number of cell types. We have shown previously that disruption of P2X7 receptor function results in downregulation of osteogenic markers and upregulation of adipogenic markers in calvarial cell cultures. In the present study, we assessed whether loss of P2X7 receptor function results in changes to adipocyte distribution and lipid accumulation in vivo. Male P2X7 loss-of-function (KO) mice exhibited significantly greater body weight and epididymal fat pad mass than wild-type (WT) mice at 9 months of age. Fat pad adipocytes did not differ in size, consistent with adipocyte hyperplasia rather than hypertrophy. Histological examination revealed ectopic lipid accumulation in the form of adipocytes and/or lipid droplets in several non-adipose tissues of older male KO mice (9-12 months of age). Ectopic lipid was observed in kidney, extraorbital lacrimal gland and pancreas, but not in liver, heart or skeletal muscle. Specifically, lacrimal gland and pancreas from 12-month-old male KO mice had greater numbers of adipocytes in perivascular, periductal and acinar regions. As well, lipid droplets accumulated in the renal tubular epithelium and lacrimal acinar cells. Blood plasma analyses revealed diminished total cholesterol levels in 9- and 12-month-old male KO mice compared with WT controls. Interestingly, no differences were observed in female mice. Moreover, there were no significant differences in food consumption between male KO and WT mice. Taken together, these data establish novel in vivo roles for the P2X7 receptor in regulating adipogenesis and lipid metabolism in an age- and sex-dependent manner.
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Thakur M, Dawes JM, McMahon SB. Genomics of pain in osteoarthritis. Osteoarthritis Cartilage 2013; 21:1374-82. [PMID: 23973152 PMCID: PMC3769859 DOI: 10.1016/j.joca.2013.06.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 06/11/2013] [Accepted: 06/13/2013] [Indexed: 02/02/2023]
Abstract
Osteoarthritis (OA) accounts for the majority of the disease burden for musculoskeletal disorders and is one of the leading causes of disability worldwide. This disability is the result not of the cartilage loss that defines OA radiographically, but of the chronic pain whose presence defines symptomatic OA. It is becoming clear that many genes, each with a small effect size, contribute to the risk of developing OA. However, the genetics of OA pain are only just starting to be explored. This review will describe the first genes to have been identified in genomic studies of OA pain, as well as the possible dual roles of genes previously identified in genomic studies of OA in the context of pain. Difficulties associated with attempting to characterise the genetics of OA pain will be discussed and promising future avenues of research into genetic and epigenetic factors affecting OA pain described.
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Affiliation(s)
- M Thakur
- Neurorestoration Group, Wolfson CARD, School of Biomedical Sciences, Kings College London Guy's Campus, London SE1 1UL, UK.
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35
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Mayer CL, Huber BR, Peskind E. Traumatic brain injury, neuroinflammation, and post-traumatic headaches. Headache 2013; 53:1523-30. [PMID: 24090534 DOI: 10.1111/head.12173] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2013] [Indexed: 12/12/2022]
Abstract
Concussions following head and/or neck injury are common, and although most people with mild injuries recover uneventfully, a subset of individuals develop persistent post-concussive symptoms that often include headaches. Post-traumatic headaches vary in presentation and may progress to become chronic and in some cases debilitating. Little is known about the pathogenesis of post-traumatic headaches, although shared pathophysiology with that of the brain injury is suspected. Following primary injury to brain tissues, inflammation rapidly ensues; while this inflammatory response initially provides a defensive/reparative function, it can persist beyond its beneficial effect, potentially leading to secondary injuries because of alterations in neuronal excitability, axonal integrity, central processing, and other changes. These changes may account for the neurological symptoms often observed after traumatic brain injury, including headaches. This review considers selected aspects of the inflammatory response following traumatic brain injury, with an emphasis on the role of glial cells as mediators of maladaptive post-traumatic inflammation.
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Affiliation(s)
- Cynthia L Mayer
- VA Northwest Network Mental Illness Research, Education, and Clinical Center, VA Puget Sound Health Care System, Seattle, WA, USA; Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, USA
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36
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Purinergic mechanisms and pain--an update. Eur J Pharmacol 2013; 716:24-40. [PMID: 23524093 DOI: 10.1016/j.ejphar.2013.01.078] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 12/11/2012] [Accepted: 01/09/2013] [Indexed: 12/12/2022]
Abstract
There is a brief summary of the background literature about purinergic signalling. The review then considers purinergic mechanosensory transduction involved in visceral, cutaneous and musculoskeletal nociception and on the roles played by P2X3, P2X2/3, P2X4, P2X7 and P2Y₁₂ receptors in neuropathic and inflammatory pain. Current developments of compounds for the therapeutic treatment of both visceral and neuropathic pain are discussed.
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37
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Balcombe J, Ferdowsian H, Briese L. Prolonged Pain Research in Mice: Trends in Reference to the 3Rs. J APPL ANIM WELF SCI 2013; 16:77-95. [DOI: 10.1080/10888705.2013.741004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Dolmatova E, Spagnol G, Boassa D, Baum JR, Keith K, Ambrosi C, Kontaridis MI, Sorgen PL, Sosinsky GE, Duffy HS. Cardiomyocyte ATP release through pannexin 1 aids in early fibroblast activation. Am J Physiol Heart Circ Physiol 2012; 303:H1208-18. [PMID: 22982782 DOI: 10.1152/ajpheart.00251.2012] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fibrosis following myocardial infarction is associated with increases in arrhythmias and sudden cardiac death. Initial steps in the development of fibrosis are not clear; however, it is likely that cardiac fibroblasts play an important role. In immune cells, ATP release from pannexin 1 (Panx1) channels acts as a paracrine signal initiating activation of innate immunity. ATP has been shown in noncardiac systems to initiate fibroblast activation. Therefore, we propose that ATP release through Panx1 channels and subsequent fibroblast activation in the heart drives the development of fibrosis in the heart following myocardial infarction. We identified for the first time that Panx1 is localized within sarcolemmal membranes of canine cardiac myocytes where it directly interacts with the postsynaptic density 95/Drosophila disk large/zonula occludens-1-containing scaffolding protein synapse-associated protein 97 via its carboxyl terminal domain (amino acids 300-357). Induced ischemia rapidly increased glycosylation of Panx1, resulting in increased trafficking to the plasma membrane as well as increased interaction with synapse-associated protein 97. Cellular stress enhanced ATP release from myocyte Panx1 channels, which, in turn, causes fibroblast transformation to the activated myofibroblast phenotype via activation of the MAPK and p53 pathways, both of which are involved in the development of cardiac fibrosis. ATP release through Panx1 channels in cardiac myocytes during ischemia may be an early paracrine event leading to profibrotic responses to ischemic cardiac injury.
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Affiliation(s)
- Elena Dolmatova
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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39
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Chen MJ, Kress B, Han X, Moll K, Peng W, Ji RR, Nedergaard M. Astrocytic CX43 hemichannels and gap junctions play a crucial role in development of chronic neuropathic pain following spinal cord injury. Glia 2012; 60:1660-70. [PMID: 22951907 DOI: 10.1002/glia.22384] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 06/14/2012] [Indexed: 12/31/2022]
Abstract
Chronic neuropathic pain is a frequent consequence of spinal cord injury (SCI). Yet despite recent advances, upstream releasing mechanisms and effective therapeutic options remain elusive. Previous studies have demonstrated that SCI results in excessive ATP release to the peritraumatic regions and that purinergic signaling, among glial cells, likely plays an essential role in facilitating inflammatory responses and nociceptive sensitization. We sought to assess the role of connexin 43 (Cx43) as a mediator of CNS inflammation and chronic pain. To determine the extent of Cx43 involvement in chronic pain, a weight-drop SCI was performed on transgenic mice with Cx43/Cx30 deletions. SCI induced robust and persistent neuropathic pain including heat hyperalgesia and mechanical allodynia in wild-type control mice, which developed after 4 weeks and was maintained after 8 weeks. Notably, SCI-induced heat hyperalgesia and mechanical allodynia were prevented in transgenic mice with Cx43/Cx30 deletions, but fully developed in transgenic mice with only Cx30 deletion. SCI-induced gliosis, detected as upregulation of glial fibrillary acidic protein in the spinal cord astrocytes at different stages of the injury, was also reduced in the knockout mice with Cx43/Cx30 deletions, when compared with littermate controls. In comparison, a standard regimen of post-SCI treatment of minocycline attenuated neuropathic pain to a significantly lesser degree than Cx43 deletion. These findings suggest Cx43 is critically linked to the development of central neuropathic pain following acute SCI. Since Cx43/Cx30 is expressed by astrocytes, these findings also support an important role of astrocytes in the development of chronic pain.
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Affiliation(s)
- Michael J Chen
- Department of Neurosurgery, Center for Translational Neuromedicine, University of Rochester Medical School, Rochester, New York, USA
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40
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Masin M, Young C, Lim K, Barnes SJ, Xu XJ, Marschall V, Brutkowski W, Mooney ER, Gorecki DC, Murrell-Lagnado R. Expression, assembly and function of novel C-terminal truncated variants of the mouse P2X7 receptor: re-evaluation of P2X7 knockouts. Br J Pharmacol 2012; 165:978-93. [PMID: 21838754 DOI: 10.1111/j.1476-5381.2011.01624.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Splice variants of P2X7 receptor transcripts contribute to the diversity of receptor-mediated responses. Here, we investigated expression and function of C-terminal truncated (ΔC) variants of the mP2X7 receptor, which are predicted to escape inactivation in one strain of P2X7(-/-) mice (Pfizer KO). EXPERIMENTAL APPROACH Expression in wild-type (WT) and Pfizer KO tissue was investigated by reverse transcription (RT)-PCR and Western blot analysis. ΔC variants were also cloned and expressed in HEK293 cells to investigate their assembly, trafficking and function. KEY RESULTS RT-PCR indicates expression of a ΔC splice variant in brain, salivary gland (SG) and spleen from WT and Pfizer KO mice. An additional ΔC hybrid transcript, containing sequences of P2X7 upstream of exon 12, part of exon 13 followed in-frame by the sequence of the vector used to disrupt the P2X7 gene, was also identified in the KO mice. By blue native (BN) PAGE analysis and the use of cross linking reagents followed by SDS-PAGE, P2X7 trimers, dimers and monomers were detected in the spleen and SG of Pfizer KO mice. The molecular mass was reduced compared with P2X7 in WT mice tissue, consistent with a ΔC variant. When expressed in HEK293 cells the ΔC variants were inefficiently trafficked to the cell surface and agonist-evoked whole cell currents were small. Co-expressed with P2X7A, the ΔC splice variant acted in a dominant negative fashion to inhibit function. CONCLUSIONS AND IMPLICATIONS Pfizer KO mice are not null for P2X7 receptor expression but express ΔC variants with reduced function.
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Affiliation(s)
- Marianela Masin
- Department of Pharmacology, University of Cambridge, Cambridge, UK
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41
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Activation of the damage-associated molecular pattern receptor P2X7 induces interleukin-1β release from canine monocytes. Vet Immunol Immunopathol 2012; 149:86-91. [PMID: 22652409 DOI: 10.1016/j.vetimm.2012.05.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Revised: 04/27/2012] [Accepted: 05/02/2012] [Indexed: 02/07/2023]
Abstract
P2X7, a damage-associated molecular pattern receptor and adenosine 5'-triphosphate (ATP)-gated cation channel, plays an important role in the activation of the NALP3 inflammasome and subsequent release of interleukin (IL)-1β from human monocytes; however its role in monocytes from other species including the dog remains poorly defined. This study investigated the role of P2X7 in canine monocytes, including its role in IL-1β release. A fixed-time flow cytometric assay demonstrated that activation of P2X7 by extracellular ATP induces the uptake of the organic cation, YO-PRO-1(2+), into peripheral blood monocytes from various dog breeds, a process impaired by the specific P2X7 antagonist, A438079. Moreover, in five different breeds, relative P2X7 function in monocytes was about half that of peripheral blood T cells but similar to that of peripheral blood B cells. Reverse transcription-PCR demonstrated the presence of P2X7, NALP3, caspase-1 and IL-1β in LPS-primed canine monocytes. Immunoblotting confirmed the presence of P2X7 in LPS-primed canine monocytes. Finally, extracellular ATP induced YO-PRO-1(2+) uptake into and IL-1β release from these cells, with both processes impaired by A438079. These results demonstrate that P2X7 activation induces the uptake of organic cations into and the release of IL-1β from canine monocytes. These findings indicate that P2X7 may play an important role in IL-1β-dependent processes in dogs.
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Cieślak M, Komoszyński M. [The role of ecto-purines in inflammation leading to demyelination - new means for therapies against multiple sclerosis]. Neurol Neurochir Pol 2012; 45:489-99. [PMID: 22127945 DOI: 10.1016/s0028-3843(14)60318-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Nucleotides released from activated and/or injured cells activate P2 receptors. Extracellular nucleotides serve as danger signals or damage-associated molecular patterns (DAMPs) that trigger various immune responses. Indeed, P2 receptors are highly expressed in the astrocytes, microglia and other immune cells such as T and B lymphocytes that migrate to the central nervous system. The activation of P2 receptors triggers the secretion of proinflammatory cytokines and chemokines as well as immune cell migration and proliferation that contribute to demyelination and axonal damage. The activation of P2 receptors is controlled by the ectonucleotidases which hydrolyze extracellular nucleotides. Ecto-NTPDases and ecto-5'-nucleotidase are expressed in the astrocytes, oligodendrocytes, microglia, endothelial cells and activated T cells. The hydrolysis of extracellular ATP and ADP by enzymes results in the generation of extracellular adenosine. This nucleoside interacts with P1 receptors and activates anti-inflammatory and immunosuppressive responses in the cells involved in MS.
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Affiliation(s)
- Marek Cieślak
- Wojewódzki Szpital Zespolony, Oddział Neurologiczny,Toruñ.
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43
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Anand P, Bley K. Topical capsaicin for pain management: therapeutic potential and mechanisms of action of the new high-concentration capsaicin 8% patch. Br J Anaesth 2011; 107:490-502. [PMID: 21852280 PMCID: PMC3169333 DOI: 10.1093/bja/aer260] [Citation(s) in RCA: 415] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Topical capsaicin formulations are used for pain management. Safety and modest efficacy of low-concentration capsaicin formulations, which require repeated daily self-administration, are supported by meta-analyses of numerous studies. A high-concentration capsaicin 8% patch (Qutenza™) was recently approved in the EU and USA. A single 60-min application in patients with neuropathic pain produced effective pain relief for up to 12 weeks. Advantages of the high-concentration capsaicin patch include longer duration of effect, patient compliance, and low risk for systemic effects or drug-drug interactions. The mechanism of action of topical capsaicin has been ascribed to depletion of substance P. However, experimental and clinical studies show that depletion of substance P from nociceptors is only a correlate of capsaicin treatment and has little, if any, causative role in pain relief. Rather, topical capsaicin acts in the skin to attenuate cutaneous hypersensitivity and reduce pain by a process best described as 'defunctionalization' of nociceptor fibres. Defunctionalization is due to a number of effects that include temporary loss of membrane potential, inability to transport neurotrophic factors leading to altered phenotype, and reversible retraction of epidermal and dermal nerve fibre terminals. Peripheral neuropathic hypersensitivity is mediated by diverse mechanisms, including altered expression of the capsaicin receptor TRPV1 or other key ion channels in affected or intact adjacent peripheral nociceptive nerve fibres, aberrant re-innervation, and collateral sprouting, all of which are defunctionalized by topical capsaicin. Evidence suggests that the utility of topical capsaicin may extend beyond painful peripheral neuropathies.
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Affiliation(s)
- P Anand
- Peripheral Neuropathy Unit, Imperial College London, Hammersmith Hospital, Area A, Ground Floor, Du Cane Road, London W12 ONN, UK.
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44
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Itoh K, Chiang CY, Li Z, Lee JC, Dostrovsky JO, Sessle BJ. Central sensitization of nociceptive neurons in rat medullary dorsal horn involves purinergic P2X7 receptors. Neuroscience 2011; 192:721-31. [PMID: 21763757 PMCID: PMC3172718 DOI: 10.1016/j.neuroscience.2011.06.083] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 06/13/2011] [Accepted: 06/28/2011] [Indexed: 12/22/2022]
Abstract
Central sensitization is a crucial process underlying the increased neuronal excitability of nociceptive pathways following peripheral tissue injury and inflammation. Our previous findings have suggested that extracellular adenosine 5'-triphosphate (ATP) molecules acting at purinergic receptors located on presynaptic terminals (e.g., P2X2/3, P2X3 subunits) and glial cells are involved in the glutamatergic-dependent central sensitization induced in medullary dorsal horn (MDH) nociceptive neurons by application to the tooth pulp of the inflammatory irritant mustard oil (MO). Since growing evidence indicates that activation of P2X7 receptors located on glia is involved in chronic inflammatory and neuropathic pain, the aim of the present study was to test in vivo for P2X7 receptor involvement in this acute inflammatory pain model. Experiments were carried out in anesthetized Sprague-Dawley male rats. Single unit recordings were made in MDH functionally identified nociceptive neurons for which mechanoreceptive field, mechanical activation threshold and responses to noxious stimuli were tested. We found that continuous intrathecal (i.t.) superfusion over MDH of the potent P2X7 receptor antagonists brilliant blue G and periodated oxidized ATP could each significantly attenuate the MO-induced MDH central sensitization. MDH central sensitization could also be produced by i.t. superfusion of ATP and even more effectively by the P2X7 receptor agonist benzoylbenzoyl ATP. Superfusion of the microglial blocker minocycline abolished the MO-induced MDH central sensitization, consistent with reports that dorsal horn P2X7 receptors are mostly expressed on microglia. In control experiments, superfusion over MDH of vehicle did not produce any significant changes. These novel findings suggest that activation of P2X7 receptors in vivo may be involved in the development of central sensitization in an acute inflammatory pain model.
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Affiliation(s)
- Kazunori Itoh
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada M5G 1G6
| | - Chen-Yu Chiang
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada M5G 1G6
| | - Zhaohui Li
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada M5G 1G6
| | - Jye-Chang Lee
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada M5G 1G6
| | - Jonathan O. Dostrovsky
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada M5G 1G6
- Department of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada M5S 1A8
| | - Barry J. Sessle
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada M5G 1G6
- Department of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada M5S 1A8
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Abstract
The myriad pain pathophysiology has intrigued and challenged humanity for centuries. In this regard, the traditional pain therapies such as opioids and nonsteroidal anti-inflammatory drugs have been highly successful in treating acute and chronic pain. However, their drawback includes adverse events such as psychotropic effects, addiction potential, and gastrointestinal toxicities, to mention a few. These factors combined with the likelihood of an increase in chronic pain conditions due to an aging population calls for the development of novel mechanism-based or "site-specific" agents to target novel pain pathways. In this regard, rapid progress has been made in understanding the molecular mechanisms of novel pain targets such as cannabinoid receptors, fatty acid hydrolase, voltage-gated and ligand-gated ion channels such as P2 receptors, transient receptor potential channels and glial cell modulators. Accordingly, preclinical studies indicate that the site-specific/selective agents exhibit sufficient efficacy and reduced side effects such as lack of psychotropic effects indicating their clinical potential. This review provides a brief summary of some "at-site" pain targets and their role in the pain pathophysiology, and describes the efforts in developing some small molecules as novel pain therapeutics.
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Affiliation(s)
- Praveen Pn Rao
- School of Pharmacy, Health Sciences Campus, University of Waterloo, Waterloo, ON, Canada
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46
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Cieślak M, Kukulski F, Komoszyński M. Emerging role of extracellular nucleotides and adenosine in multiple sclerosis. Purinergic Signal 2011; 7:393-402. [PMID: 21792574 PMCID: PMC3224637 DOI: 10.1007/s11302-011-9250-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 07/11/2011] [Indexed: 12/12/2022] Open
Abstract
Extracellular nucleotides and adenosine play important roles in inflammation. These signaling molecules interact with the cell-surface-located P2 and P1 receptors, respectively, that are widely distributed in the central nervous system and generally exert opposite effects on immune responses. Indeed, extracellular ATP, ADP, UTP, and UDP serve as alarmins or damage-associated molecular patterns that activate mainly proinflammatory mechanisms, whereas adenosine has potent anti-inflammatory and immunosuppressive effects. This review discusses the actual and potential role of extracellular nucleotides and adenosine in multiple sclerosis (MS).
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Affiliation(s)
- Marek Cieślak
- Department of Neurology, WSZ Hospital, 53/59 St. Joseph Street, Toruń, 87-100, Poland,
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47
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Lenertz LY, Gavala ML, Zhu Y, Bertics PJ. Transcriptional control mechanisms associated with the nucleotide receptor P2X7, a critical regulator of immunologic, osteogenic, and neurologic functions. Immunol Res 2011; 50:22-38. [PMID: 21298493 PMCID: PMC3203638 DOI: 10.1007/s12026-011-8203-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The nucleotide receptor P2X(7) is an attractive therapeutic target and potential biomarker for multiple inflammatory and neurologic disorders, and it is expressed in several immune, osteogenic, and neurologic cell types. Aside from its role in the nervous system, it is activated by ATP released at sites of tissue damage, inflammation, and infection. Ligand binding to P2X(7) stimulates many cell responses, including calcium fluxes, MAPK activation, inflammatory mediator release, and apoptosis. Much work has centered on P2X(7) action in cell death and mediator processing (e.g., pro-interleukin-1 cleavage by the inflammasome), but the contribution of P2X(7) to transcriptional regulation is less well defined. This review will focus on the growing evidence for the importance of nucleotide-mediated gene expression, highlight several animal models, human genetic, and clinical studies that support P2X(7) as a therapeutic target, and discuss the latest developments in anti-P2X(7) clinical trials.
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Affiliation(s)
- Lisa Y. Lenertz
- Department of Biomolecular Chemistry, School of Medicine and Public Health, The University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Monica L. Gavala
- Department of Biomolecular Chemistry, School of Medicine and Public Health, The University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Yiming Zhu
- Department of Biomolecular Chemistry, School of Medicine and Public Health, The University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Paul J. Bertics
- Department of Biomolecular Chemistry, School of Medicine and Public Health, The University of Wisconsin-Madison, Madison, Wisconsin 53706
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Mishra A, Chintagari NR, Guo Y, Weng T, Su L, Liu L. Purinergic P2X7 receptor regulates lung surfactant secretion in a paracrine manner. J Cell Sci 2011; 124:657-68. [PMID: 21266468 DOI: 10.1242/jcs.066977] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Alveolar epithelium is composed of alveolar epithelial cells of type I (AEC I) and type II (AEC II). AEC II secrete lung surfactant by means of exocytosis. P2X(7) receptor (P2X(7)R), a P2 purinergic receptor, has been implicated in the regulation of synaptic transmission and inflammation. Here, we report that P2X(7)R, which is expressed in AEC I but not AEC II, is a novel mediator for the paracrine regulation of surfactant secretion in AEC II. In primary co-cultures of AEC I and AEC II benzoyl ATP (BzATP; an agonist of P2X(7)R) increased surfactant secretion, which was blocked by the P2X(7)R antagonist Brilliant Blue G. This effect was observed in AEC II co-cultured with human embryonic kidney HEK-293 cells stably expressing rat P2X(7)R, but not when co-cultured with AEC I in which P2X(7)R was knocked down or in co-cultures of AEC I and AEC II isolated from P2X(7)R(-/-) mice. BzATP-mediated secretion involved P2Y(2) receptor signaling because it was reduced by the addition of the ATP scavengers apyrase and adenosine deaminase and the P2Y(2) receptor antagonist suramin. However, the stimulation with BzATP might also release other substances that potentially increase surfactant secretion as a greater stimulation of secretion was observed in AEC II incubated with BzATP when co-cultured with E10 or HEK-293-P2X(7)R cells than with ATP alone. P2X(7)R(-/-) mice failed to increase surfactant secretion in response to hyperventilation, pointing to the physiological relevance of P2X(7)R in maintaining surfactant homeostasis in the lung. These results suggest that the activation of P2X(7)R increases surfactant secretion by releasing ATP from AEC I and subsequently stimulating P2Y(2) receptors in AEC II.
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Affiliation(s)
- Amarjit Mishra
- Lundberg-Kienlen Lung Biology and Toxicology Laboratory, Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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Burnstock G, Kennedy C. P2X receptors in health and disease. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2011; 61:333-372. [PMID: 21586364 DOI: 10.1016/b978-0-12-385526-8.00011-4] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Seven P2X receptor subunits have been cloned which form functional homo- and heterotrimers. These are cation-selective channels, equally permeable to Na(+) and K(+) and with significant Ca(2+) permeability. The three-dimensional structure of the P2X receptor is described. The channel pore is formed by the α-helical transmembrane spanning region 2 of each subunit. When ATP binds to a P2X receptor, the pore opens within milliseconds, allowing the cations to flow. P2X receptors are expressed on both central and peripheral neurons, where they are involved in neuromuscular and synaptic neurotransmission and neuromodulation. They are also expressed in most types of nonneuronal cells and mediate a wide range of actions, such as contraction of smooth muscle, secretion, and immunomodulation. Changes in the expression of P2X receptors have been characterized in many pathological conditions of the cardiovascular, gastrointestinal, respiratory, and urinogenital systems and in the brain and special senses. The therapeutic potential of P2X receptor agonists and antagonists is currently being investigated in a range of disorders, including chronic neuropathic and inflammatory pain, depression, cystic fibrosis, dry eye, irritable bowel syndrome, interstitial cystitis, dysfunctional urinary bladder, and cancer.
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Affiliation(s)
- G Burnstock
- Autonomic Neuroscience Centre, University College Medical School, London, United Kingdom
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Chu YX, Zhang Y, Zhang YQ, Zhao ZQ. Involvement of microglial P2X7 receptors and downstream signaling pathways in long-term potentiation of spinal nociceptive responses. Brain Behav Immun 2010; 24:1176-89. [PMID: 20554014 DOI: 10.1016/j.bbi.2010.06.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 05/21/2010] [Accepted: 06/02/2010] [Indexed: 12/23/2022] Open
Abstract
Tetanic stimulation of the sciatic nerve (TSS) produces long-term potentiation (LTP) of C-fiber-evoked field potentials in the spinal cord. This potentiation is considered to be a substrate for long-lasting sensitization in the spinal pain pathway. Because microglia have previously been shown to regulate the induction of spinal LTP, we hypothesize that P2X7 receptors (P2X7R), which are predominantly expressed in microglia and participate in the communication between microglia and neurons, may play a role in this induction. This study investigated the potential roles of P2X7Rs in spinal LTP and persistent pain induced by TSS in rats. OxATP or BBG, a P2X7R antagonist, prevented the induction of spinal LTP both in vivo and in spinal cord slices in vitro and alleviated mechanical allodynia. Down-regulation of P2X7Rs with P2X7-siRNA blocked the induction of spinal LTP and inhibited mechanical allodynia. Double immunofluorescence showed colocalization of P2X7Rs with the microglial marker OX-42, but not with the astrocytic marker GFAP or the neuronal marker NeuN. Intrathecal injection of BBG suppressed the up-regulation of microglial P2X7Rs and increased expression of Fos in the spinal superficial dorsal horn. Further, pre-administration of BBG inhibited increased expression of the microglial marker Iba-1, phosphorylated p38 (p-p38), interleukin 1β (IL-1β) and GluR1 following TSS. Pre-administration of the IL-1 receptor antagonist (IL-1ra) blocked both the induction of spinal LTP and the up-regulation of GluR1. These results suggest that microglial P2X7Rs and its downstream signaling pathways play a pivotal role in the induction of spinal LTP and persistent pain induced by TSS.
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Affiliation(s)
- Yu-Xia Chu
- Institute of Neurobiology, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
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