1
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Martins MS, Almeida IF, Cruz MT, Sousa E. Chronic pruritus: from pathophysiology to drug design. Biochem Pharmacol 2023; 212:115568. [PMID: 37116666 DOI: 10.1016/j.bcp.2023.115568] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 04/17/2023] [Accepted: 04/18/2023] [Indexed: 04/30/2023]
Abstract
Pruritus, the most common symptom in dermatology, is an innate response capable of protecting skin against irritants. Nonetheless, when it lasts more than six weeks it is assumed to be a chronic pathology having a negative impact on people's lives. Chronic pruritus (CP) can occur in common and rare skin diseases, having a high prevalence in global population. The existing therapies are unable to counteract CP or are associated with adverse effects, so the development of effective treatments is a pressing issue. The pathophysiological mechanisms underlying CP are not yet completely dissected but, based on current knowledge, involve a wide range of receptors, namely neurokinin 1 receptor (NK1R), Janus kinase (JAK), and transient receptor potential (TRP) ion channels, especially transient receptor potential vanilloid 1 (TRPV1) and transient receptor potential ankyrin 1 (TRPA1). This review will address the relevance of these molecular targets for the treatment of CP and molecules capable of modulating these receptors that have already been studied clinically or have the potential to possibly alleviate this pathology. According to scientific and clinical literature, there is an increase in the expression of these molecular targets in the lesioned skin of patients experiencing CP when compared with non-lesioned skin, highlighting their importance for the development of potential efficacious drugs through the design of antagonists/inhibitors.
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Affiliation(s)
- Márcia S Martins
- CIIMAR-Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Novo Edifício do Terminal de Cruzeiros do Porto de Leixões, 4450-208 Matosinhos, Portugal; Laboratory of Organic and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Isaobel F Almeida
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal; UCIBIO-Applied Molecular Biosciences Unit, MedTech, Laboratory of Pharmaceutical Technology, Department of Drug Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal.
| | - Maria T Cruz
- CNC-Center for Neuroscience and Cell Biology, CIBB-Center for Innovative Biomedicine and Biotechnology, University of Coimbra, 3004-504 Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Emília Sousa
- CIIMAR-Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Novo Edifício do Terminal de Cruzeiros do Porto de Leixões, 4450-208 Matosinhos, Portugal; Laboratory of Organic and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal.
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2
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Lin J, Taggart M, Borthwick L, Fisher A, Brodlie M, Sassano MF, Tarran R, Gray MA. Acute cigarette smoke or extract exposure rapidly activates TRPA1-mediated calcium influx in primary human airway smooth muscle cells. Sci Rep 2021; 11:9643. [PMID: 33953304 PMCID: PMC8100124 DOI: 10.1038/s41598-021-89051-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 04/19/2021] [Indexed: 11/09/2022] Open
Abstract
Tobacco smoking is the largest risk factor for developing chronic obstructive pulmonary disease (COPD), and is associated with hyperresponsiveness of airway smooth muscle (ASM). Chronic exposure to cigarette smoke (CS) leads to airway inflammation and remodelling. However, the direct effect of gaseous CS or CS extract (CSE) on human airway smooth muscle cell (hASMC) function remains poorly understood. This study investigated the acute effect of CS/CSE on calcium homeostasis, a key regulator of ASM physiology and pathophysiology. Primary hASMC were isolated from non-smoking donor lungs, and subjected to Ca2+ imaging studies. We found that both CS, and CSE, rapidly elevated cytosolic Ca2+ in hASMC through stimulation of plasmalemmal Ca2+ influx, but excluded store-operated and L-type Ca2+ channels as mediators of this effect. Using a specific pharmacological inhibitor, or shRNA-driven knockdown, we established that both CS and CSE stimulated Ca2+ influx in hASMC through the neurogenic pain receptor channel, transient receptor potential ankyrin 1 (TRPA1). CS/CSE-dependent, TRPA1-mediated Ca2+ influx led to myosin light-chain phosphorylation, a key process regulating ASM contractility. We conclude that TRPA1 is likely an important link between CS/CSE exposure and airway hyperresponsiveness, and speculate that acute CS/CSE-induced Ca2+ influx could lead to exacerbated ASM contraction and potentially initiate further chronic pathological effects of tobacco smoke.
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Affiliation(s)
- JinHeng Lin
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, Tyne and Wear, UK
| | - Michael Taggart
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, Tyne and Wear, UK
| | - Lee Borthwick
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, Tyne and Wear, UK
| | - Andrew Fisher
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, Tyne and Wear, UK
| | - Malcolm Brodlie
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, Tyne and Wear, UK
- Paediatric Respiratory Medicine, Great North Children's Hospital, Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, Tyne and Wear, UK
| | - M Flori Sassano
- Department of Cell Biology and Physiology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Robert Tarran
- Department of Cell Biology and Physiology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Michael A Gray
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, Tyne and Wear, UK.
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3
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Haustrate A, Hantute-Ghesquier A, Prevarskaya N, Lehen'kyi V. Monoclonal Antibodies Targeting Ion Channels and Their Therapeutic Potential. Front Pharmacol 2019; 10:606. [PMID: 31231216 PMCID: PMC6561378 DOI: 10.3389/fphar.2019.00606] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 05/14/2019] [Indexed: 12/27/2022] Open
Abstract
Monoclonal antibodies (mAbs) represent a rapidly growing pharmaceutical class of protein drugs that becomes an important part of the precision therapy. mAbs are characterized by their high specificity and affinity for the target antigen, which is mostly present on the cell surface. Ion channels are a large family of transmembrane proteins that control ion transport across the cell membrane. They are involved in almost all biological processes in both health and disease and are widely considered as prospective targets. However, no antibody-based drug targeting ion channel has been developed so far that has progressed to clinical use. Thus, we provide a comprehensive review of the elaborated mAbs against ion channels, describe their mechanisms of action, and discuss their therapeutic potential.
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Affiliation(s)
- Aurélien Haustrate
- Laboratory of Cell Physiology, INSERM U1003, Laboratory of Excellence Ion Channel Science and Therapeutics, Department of Biology, Faculty of Science and Technologies, University of Lille, Villeneuve d'Ascq, France
| | - Aline Hantute-Ghesquier
- Laboratory of Cell Physiology, INSERM U1003, Laboratory of Excellence Ion Channel Science and Therapeutics, Department of Biology, Faculty of Science and Technologies, University of Lille, Villeneuve d'Ascq, France
| | - Natalia Prevarskaya
- Laboratory of Cell Physiology, INSERM U1003, Laboratory of Excellence Ion Channel Science and Therapeutics, Department of Biology, Faculty of Science and Technologies, University of Lille, Villeneuve d'Ascq, France
| | - V'yacheslav Lehen'kyi
- Laboratory of Cell Physiology, INSERM U1003, Laboratory of Excellence Ion Channel Science and Therapeutics, Department of Biology, Faculty of Science and Technologies, University of Lille, Villeneuve d'Ascq, France.,FONDATION ARC, Villejuif, France
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4
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Viana F. TRPA1 channels: molecular sentinels of cellular stress and tissue damage. J Physiol 2017; 594:4151-69. [PMID: 27079970 DOI: 10.1113/jp270935] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 03/31/2016] [Indexed: 01/08/2023] Open
Abstract
TRPA1 is a non-selective cation channel expressed in mammalian peripheral pain receptors, with a major role in chemonociception. TRPA1 has also been implicated in noxious cold and mechanical pain sensation. TRPA1 has an ancient origin and plays important functions in lower organisms, including thermotaxis, mechanotransduction and modulation of lifespan. Here we highlight the role of TRPA1 as a multipurpose sensor of harmful signals, including toxic bacterial products and UV light, and as a sensor of stress and tissue damage. Sensing roles span beyond the peripheral nervous system to include major barrier tissues: gut, skin and lung. Tissue injury, environmental irritants and microbial pathogens are danger signals that can threaten the health of organisms. These signals lead to the coordinated activation of the nociceptive and the innate immune system to provide a homeostatic response trying to re-establish physiological conditions including tissue repair. Activation of TRPA1 participates in protective neuroimmune interactions at multiple levels, sensing ROS and bacterial products and triggering the release of neuropeptides. However, an exaggerated response to danger signals is maladaptive and can lead to the development of chronic inflammatory conditions.
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Affiliation(s)
- Félix Viana
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Alicante, Spain
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5
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Rouwette T, Sondermann J, Avenali L, Gomez-Varela D, Schmidt M. Standardized Profiling of The Membrane-Enriched Proteome of Mouse Dorsal Root Ganglia (DRG) Provides Novel Insights Into Chronic Pain. Mol Cell Proteomics 2016; 15:2152-68. [PMID: 27103637 DOI: 10.1074/mcp.m116.058966] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Indexed: 01/08/2023] Open
Abstract
Chronic pain is a complex disease with limited treatment options. Several profiling efforts have been employed with the aim to dissect its molecular underpinnings. However, generated results are often inconsistent and nonoverlapping, which is largely because of inherent technical constraints. Emerging data-independent acquisition (DIA)-mass spectrometry (MS) has the potential to provide unbiased, reproducible and quantitative proteome maps - a prerequisite for standardization among experiments. Here, we designed a DIA-based proteomics workflow to profile changes in the abundance of dorsal root ganglia (DRG) proteins in two mouse models of chronic pain, inflammatory and neuropathic. We generated a DRG-specific spectral library containing 3067 DRG proteins, which enables their standardized quantification by means of DIA-MS in any laboratory. Using this resource, we profiled 2526 DRG proteins in each biological replicate of both chronic pain models and respective controls with unprecedented reproducibility. We detected numerous differentially regulated proteins, the majority of which exhibited pain model-specificity. Our approach recapitulates known biology and discovers dozens of proteins that have not been characterized in the somatosensory system before. Functional validation experiments and analysis of mouse pain behaviors demonstrate that indeed meaningful protein alterations were discovered. These results illustrate how the application of DIA-MS can open new avenues to achieve the long-awaited standardization in the molecular dissection of pathologies of the somatosensory system. Therefore, our findings provide a valuable framework to qualitatively extend our understanding of chronic pain and somatosensation.
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Affiliation(s)
- Tom Rouwette
- From the ‡Somatosensory Signaling and Systems Biology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Goettingen, Germany
| | - Julia Sondermann
- From the ‡Somatosensory Signaling and Systems Biology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Goettingen, Germany
| | - Luca Avenali
- From the ‡Somatosensory Signaling and Systems Biology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Goettingen, Germany
| | - David Gomez-Varela
- From the ‡Somatosensory Signaling and Systems Biology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Goettingen, Germany
| | - Manuela Schmidt
- From the ‡Somatosensory Signaling and Systems Biology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Goettingen, Germany
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6
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Fresno N, Pérez-Fernández R, Goicoechea C, Alkorta I, Fernández-Carvajal A, de la Torre-Martínez R, Quirce S, Ferrer-Montiel A, Martín MI, Goya P, Elguero J. Adamantyl analogues of paracetamol as potent analgesic drugs via inhibition of TRPA1. PLoS One 2014; 9:e113841. [PMID: 25438056 PMCID: PMC4249970 DOI: 10.1371/journal.pone.0113841] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 10/31/2014] [Indexed: 01/31/2023] Open
Abstract
Paracetamol also known as acetaminophen, is a widely used analgesic and antipyretic agent. We report the synthesis and biological evaluation of adamantyl analogues of paracetamol with important analgesic properties. The mechanism of nociception of compound 6a/b, an analog of paracetamol, is not exerted through direct interaction with cannabinoid receptors, nor by inhibiting COX. It behaves as an interesting selective TRPA1 channel antagonist, which may be responsible for its analgesic properties, whereas it has no effect on the TRPM8 nor TRPV1 channels. The possibility of replacing a phenyl ring by an adamantyl ring opens new avenues in other fields of medicinal chemistry.
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Affiliation(s)
- Nieves Fresno
- Instituto de Química Médica, IQM-CSIC, Madrid, Spain
| | | | - Carlos Goicoechea
- Departamento de Farmacología y Nutrición, Unidad Asociada de I+D+i al CSIC, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Alcorcón, Madrid, Spain
| | - Ibon Alkorta
- Instituto de Química Médica, IQM-CSIC, Madrid, Spain
- * E-mail:
| | | | | | - Susana Quirce
- Institute of Molecular and Cellular Biology, Universidad Miguel Hernández, Alicante, Spain
| | - Antonio Ferrer-Montiel
- Institute of Molecular and Cellular Biology, Universidad Miguel Hernández, Alicante, Spain
| | - M. Isabel Martín
- Departamento de Farmacología y Nutrición, Unidad Asociada de I+D+i al CSIC, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Alcorcón, Madrid, Spain
| | - Pilar Goya
- Instituto de Química Médica, IQM-CSIC, Madrid, Spain
| | - José Elguero
- Instituto de Química Médica, IQM-CSIC, Madrid, Spain
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7
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Lee KJ, Wang W, Padaki R, Bi V, Plewa CA, Gavva NR. Mouse monoclonal antibodies to transient receptor potential ankyrin 1 act as antagonists of multiple modes of channel activation. J Pharmacol Exp Ther 2014; 350:223-31. [PMID: 24893987 DOI: 10.1124/jpet.114.215574] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The transient receptor potential ankyrin 1 (TRPA1) channel has been implicated in different pathophysiologies that include asthma, cough, itch, and inflammatory pain. Agonists of TRPA1 such as mustard oil and its key component allyl isothiocyanate (AITC) cause pain and neurogenic inflammation in humans and pain behaviors in rodents. Hence, TRPA1 antagonists are being pursued as potential therapeutics. With the goal of generating monoclonal antibodies (mAbs) to human TRPA1 that could act as selective antagonists, we immunized mice with a variety of antigens expressing TRPA1 channels. After generation of hybridomas, the hybridoma conditioned media were screened to identify the mAbs that bind TRPA1 channels by a flow cytometry assay utilizing U2OS or Chinese hamster ovary (CHO) cells stably expressing TRPA1. The purified IgGs from the hybridomas that showed selective binding to TRPA1 were evaluated for antagonism in agonist-induced (45)Ca(2+) uptake assays using CHO-TRPA1 cells. Several of the mAbs showed concentration-dependent inhibition of AITC and cold (4°C) activation of TRPA1. The most potent mAb, 2B10, had IC50 values of approximately 260 and 90 nM in the two assays, respectively. These antagonist mAbs also blocked osmotically activated TRPA1 as well as activation by an endogenous agonist (4-oxo-2-nonenal). In summary, we generated mouse mAbs against TRPA1 that act as antagonists of multiple modes of TRPA1 activation.
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Affiliation(s)
- Ki Jeong Lee
- Departments of Therapeutic Discovery (K.J.L., R.P., V.B., C.A.P.) and Neuroscience (W.W., N.R.G.), Amgen Inc., Thousand Oaks, California
| | - Weiya Wang
- Departments of Therapeutic Discovery (K.J.L., R.P., V.B., C.A.P.) and Neuroscience (W.W., N.R.G.), Amgen Inc., Thousand Oaks, California
| | - Rupa Padaki
- Departments of Therapeutic Discovery (K.J.L., R.P., V.B., C.A.P.) and Neuroscience (W.W., N.R.G.), Amgen Inc., Thousand Oaks, California
| | - Vivian Bi
- Departments of Therapeutic Discovery (K.J.L., R.P., V.B., C.A.P.) and Neuroscience (W.W., N.R.G.), Amgen Inc., Thousand Oaks, California
| | - Cherylene A Plewa
- Departments of Therapeutic Discovery (K.J.L., R.P., V.B., C.A.P.) and Neuroscience (W.W., N.R.G.), Amgen Inc., Thousand Oaks, California
| | - Narender R Gavva
- Departments of Therapeutic Discovery (K.J.L., R.P., V.B., C.A.P.) and Neuroscience (W.W., N.R.G.), Amgen Inc., Thousand Oaks, California
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8
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Gui J, Liu B, Cao G, Lipchik AM, Perez M, Dekan Z, Mobli M, Daly NL, Alewood PF, Parker LL, King GF, Zhou Y, Jordt SE, Nitabach MN. A tarantula-venom peptide antagonizes the TRPA1 nociceptor ion channel by binding to the S1-S4 gating domain. Curr Biol 2014; 24:473-83. [PMID: 24530065 DOI: 10.1016/j.cub.2014.01.013] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 11/22/2013] [Accepted: 01/08/2014] [Indexed: 01/01/2023]
Abstract
BACKGROUND The venoms of predators have been an excellent source of diverse highly specific peptides targeting ion channels. Here we describe the first known peptide antagonist of the nociceptor ion channel transient receptor potential ankyrin 1 (TRPA1). RESULTS We constructed a recombinant cDNA library encoding ∼100 diverse GPI-anchored peptide toxins (t-toxins) derived from spider venoms and screened this library by coexpression in Xenopus oocytes with TRPA1. This screen resulted in identification of protoxin-I (ProTx-I), a 35-residue peptide from the venom of the Peruvian green-velvet tarantula, Thrixopelma pruriens, as the first known high-affinity peptide TRPA1 antagonist. ProTx-I was previously identified as an antagonist of voltage-gated sodium (NaV) channels. We constructed a t-toxin library of ProTx-I alanine-scanning mutants and screened this library against NaV1.2 and TRPA1. This revealed distinct partially overlapping surfaces of ProTx-I by which it binds to these two ion channels. Importantly, this mutagenesis yielded two novel ProTx-I variants that are only active against either TRPA1or NaV1.2. By testing its activity against chimeric channels, we identified the extracellular loops of the TRPA1 S1-S4 gating domain as the ProTx-I binding site. CONCLUSIONS These studies establish our approach, which we term "toxineering," as a generally applicable method for isolation of novel ion channel modifiers and design of ion channel modifiers with altered specificity. They also suggest that ProTx-I will be a valuable pharmacological reagent for addressing biophysical mechanisms of TRPA1 gating and the physiology of TRPA1 function in nociceptors, as well as for potential clinical application in the context of pain and inflammation.
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Affiliation(s)
- Junhong Gui
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT 06520, USA; Department of Genetics, Yale School of Medicine, New Haven, CT 06520, USA; Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, CT 06520, USA
| | - Boyi Liu
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Guan Cao
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT 06520, USA; Department of Genetics, Yale School of Medicine, New Haven, CT 06520, USA; Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, CT 06520, USA
| | - Andrew M Lipchik
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA
| | - Minervo Perez
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA
| | - Zoltan Dekan
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Mehdi Mobli
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Norelle L Daly
- Centre for Biodiscovery and Molecular Development of Therapeutics, Queensland Tropical Health Alliance, James Cook University, Cairns, QLD 4870, Australia
| | - Paul F Alewood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Laurie L Parker
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Yufeng Zhou
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Sven-Eric Jordt
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Michael N Nitabach
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT 06520, USA; Department of Genetics, Yale School of Medicine, New Haven, CT 06520, USA; Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, CT 06520, USA.
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9
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Abstract
The transient receptor potential ankyrin subtype 1 protein (TRPA1) is a nonselective cation channel permeable to Ca(2+), Na(+), and K(+). TRPA1 is a promiscuous chemical nocisensor that is also involved in noxious cold and mechanical sensation. It is present in a subpopulation of Aδ- and C-fiber nociceptive sensory neurons as well as in other sensory cells including epithelial cells. In primary sensory neurons, Ca(2+) and Na(+) flowing through TRPA1 into the cell cause membrane depolarization, action potential discharge, and neurotransmitter release both at peripheral and central neural projections. In addition to being activated by cysteine and lysine reactive electrophiles and oxidants, TRPA1 is indirectly activated by pro-inflammatory agents via the phospholipase C signaling pathway, in which cytosolic Ca(2+) is an important regulator of channel gating. The finding that non-electrophilic compounds, including menthol and cannabinoids, activate TRPA1 may provide templates for the design of non-tissue damaging activators to fine-tune the activity of TRPA1 and raises the possibility that endogenous ligands sharing binding sites with such non-electrophiles exist and regulate TRPA1 channel activity. TRPA1 is promising as a drug target for novel treatments of pain, itch, and sensory hyperreactivity in visceral organs including the airways, bladder, and gastrointestinal tract.
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Affiliation(s)
- Peter M Zygmunt
- Clinical and Experimental Pharmacology, Clinical Chemistry, Department of Laboratory Medicine, Lund University, Skåne University Hospital, SE-221 85, Lund, Sweden,
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10
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Bagal SK, Brown AD, Cox PJ, Omoto K, Owen RM, Pryde DC, Sidders B, Skerratt SE, Stevens EB, Storer RI, Swain NA. Ion Channels as Therapeutic Targets: A Drug Discovery Perspective. J Med Chem 2012; 56:593-624. [DOI: 10.1021/jm3011433] [Citation(s) in RCA: 198] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sharan K. Bagal
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Alan D. Brown
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Peter J. Cox
- Pfizer Neusentis, The
Portway Building, Granta Park, Great Abington, Cambridge, CB21
6GS, U.K
| | - Kiyoyuki Omoto
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Robert M. Owen
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - David C. Pryde
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Benjamin Sidders
- Pfizer Neusentis, The
Portway Building, Granta Park, Great Abington, Cambridge, CB21
6GS, U.K
| | - Sarah E. Skerratt
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Edward B. Stevens
- Pfizer Neusentis, The
Portway Building, Granta Park, Great Abington, Cambridge, CB21
6GS, U.K
| | - R. Ian Storer
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Nigel A. Swain
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
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11
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Vay L, Gu C, McNaughton PA. Current perspectives on the modulation of thermo-TRP channels: new advances and therapeutic implications. Expert Rev Clin Pharmacol 2012; 3:687-704. [PMID: 22111750 DOI: 10.1586/ecp.10.41] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The thermo transient receptor potential (TRP) ion channels, a recently discovered family of ion channels activated by temperature, are expressed in primary sensory nerve terminals, where they provide information regarding thermal changes in the environment. Six thermo-TRPs have been characterized to date: TRPV1-4, which respond to different levels of warmth and heat, and TRPM8 and TRPA1, which respond to cool temperatures. We review the current state of knowledge of thermo-TRPs, and of the modulation of their thermal thresholds by a range of inflammatory mediators. Blockers of these channels are likely to have therapeutic uses as novel analgesics but may also cause unacceptable side effects. Controlling the modulation of thermo-TRPs by inflammatory mediators may be a useful alternative strategy in developing novel analgesics.
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Affiliation(s)
- Laura Vay
- Deptartment of Pharmacology, University of Cambridge, Tennis Court Rd, Cambridge, CB2 1PD, UK
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12
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Capasso R, Aviello G, Romano B, Borrelli F, De Petrocellis L, Di Marzo V, Izzo AA. Modulation of mouse gastrointestinal motility by allyl isothiocyanate, a constituent of cruciferous vegetables (Brassicaceae): evidence for TRPA1-independent effects. Br J Pharmacol 2012; 165:1966-1977. [PMID: 21955242 DOI: 10.1111/j.1476-5381.2011.01703.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND AND PURPOSE Allyl isothiocyanate (AITC, mustard oil), a constituent of many common cruciferous vegetables (Brassicaceae), activates transient receptor potential of ankyrin type-1 (TRPA1) channels, claimed to regulate gastrointestinal contractility. In this study, we have investigated the effect of AITC on intestinal motility. EXPERIMENTAL APPROACH Effects of AITC were investigated in vivo on upper gastrointestinal transit in mice and in mouse isolated ileum [contractions induced by electrical field stimulation (EFS), acetylcholine and spontaneous contractility]. The contractor activity of AITC was studied in mouse isolated colon. The ability of TRPA1 channel antagonists to block AITC-induced elevation of intracellular Ca(2+) [Ca(2+)](i) was assessed in HEK293 cells transfected with rat TRPA1 channels. KEY RESULTS AITC increased [Ca(2+)](i) in HEK293 cells, reduced ileal contractility (acetylcholine-, EFS-induced contractions and spontaneous contractility), but contracted the isolated colon. Gentamicin and camphor (non-selective TRPA1 channel antagonists), HC-030031 and AP18 (selective TRPA1 channel agonists) inhibited AITC-induced effects in HEK293 cells but not in the ileum or colon. AITC-induced contractions were reduced by tetrodotoxin and strongly reduced by nifedipine, cyclopiazonic acid and ryanodine. In vivo, AITC reduced (following i.p. administration) or increased (following intragastric administration) upper gastrointestinal transit in mice These effects were not affected by HC-030031. CONCLUSION AND IMPLICATIONS AITC, depending, in vitro, on the regions of gut examined and, in vivo, on the route of administration, exerted both stimulatory and inhibitory effects on intestinal motility, which were not sensitive to TRPA1 channel antagonists. The proposition that TRPA1 channels are the primary targets for AITC to induce contraction should be revised.
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Affiliation(s)
- Raffaele Capasso
- Department of Experimental Pharmacology, Endocannabinoid Research Group, University of Naples Federico II, Naples, ItalyInstitute of Biomolecular Chemistry, Endocannabinoid Research Group, National Research Council, Pozzuoli (NA), Italy
| | - Gabriella Aviello
- Department of Experimental Pharmacology, Endocannabinoid Research Group, University of Naples Federico II, Naples, ItalyInstitute of Biomolecular Chemistry, Endocannabinoid Research Group, National Research Council, Pozzuoli (NA), Italy
| | - Barbara Romano
- Department of Experimental Pharmacology, Endocannabinoid Research Group, University of Naples Federico II, Naples, ItalyInstitute of Biomolecular Chemistry, Endocannabinoid Research Group, National Research Council, Pozzuoli (NA), Italy
| | - Francesca Borrelli
- Department of Experimental Pharmacology, Endocannabinoid Research Group, University of Naples Federico II, Naples, ItalyInstitute of Biomolecular Chemistry, Endocannabinoid Research Group, National Research Council, Pozzuoli (NA), Italy
| | - Luciano De Petrocellis
- Department of Experimental Pharmacology, Endocannabinoid Research Group, University of Naples Federico II, Naples, ItalyInstitute of Biomolecular Chemistry, Endocannabinoid Research Group, National Research Council, Pozzuoli (NA), Italy
| | - Vincenzo Di Marzo
- Department of Experimental Pharmacology, Endocannabinoid Research Group, University of Naples Federico II, Naples, ItalyInstitute of Biomolecular Chemistry, Endocannabinoid Research Group, National Research Council, Pozzuoli (NA), Italy
| | - Angelo A Izzo
- Department of Experimental Pharmacology, Endocannabinoid Research Group, University of Naples Federico II, Naples, ItalyInstitute of Biomolecular Chemistry, Endocannabinoid Research Group, National Research Council, Pozzuoli (NA), Italy
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13
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Bharate SS, Bharate SB. Modulation of thermoreceptor TRPM8 by cooling compounds. ACS Chem Neurosci 2012; 3:248-67. [PMID: 22860192 PMCID: PMC3369806 DOI: 10.1021/cn300006u] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 02/13/2012] [Indexed: 02/06/2023] Open
Abstract
ThermoTRPs, a subset of the Transient Receptor Potential (TRP) family of cation channels, have been implicated in sensing temperature. TRPM8 and TRPA1 are both activated by cooling. TRPM8 is activated by innocuous cooling (<30 °C) and contributes to sensing unpleasant cold stimuli or mediating the effects of cold analgesia and is a receptor for menthol and icilin (mint-derived and synthetic cooling compounds, respectively). TRPA1 (Ankyrin family) is activated by noxious cold (<17 °C), icilin, and a variety of pungent compounds. Extensive amount of medicinal chemistry efforts have been published mainly in the form of patent literature on various classes of cooling compounds by various pharmaceutical companies; however, no prior comprehensive review has been published. When expressed in heterologous expression systems, such as Xenopus oocytes or mammalian cell lines, TRPM8 mediated currents are activated by a number of cooling compounds in addition to menthol and icilin. These include synthetic p-menthane carboxamides along with other class of compounds such as aliphatic/alicyclic alcohols/esters/amides, sulphones/sulphoxides/sulphonamides, heterocyclics, keto-enamines/lactams, and phosphine oxides. In the present review, the medicinal chemistry of various cooling compounds as activators of thermoTRPM8 channel will be discussed according to their chemical classes. The potential of these compounds to emerge as therapeutic agents is also discussed.
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Affiliation(s)
- Sonali S. Bharate
- Department of Pharmaceutics, P.E. Society’s Modern
College of Pharmacy for Ladies, Dehu-Alandi Road, Moshi,
Pune, India
| | - Sandip B. Bharate
- Medicinal
Chemistry Division, Indian Institute of Integrative Medicine
(CSIR), Canal
Road, Jammu-180001, India
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14
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Vay L, Gu C, McNaughton PA. The thermo-TRP ion channel family: properties and therapeutic implications. Br J Pharmacol 2012; 165:787-801. [PMID: 21797839 PMCID: PMC3312478 DOI: 10.1111/j.1476-5381.2011.01601.x] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 04/13/2011] [Accepted: 05/01/2011] [Indexed: 01/09/2023] Open
Abstract
The thermo-transient receptor potentials (TRPs), a recently discovered family of ion channels activated by temperature, are expressed in primary sensory nerve terminals where they provide information about thermal changes in the environment. Six thermo-TRPs have been characterised to date: TRP vanilloid (TRPV) 1 and 2 are activated by painful levels of heat, TRPV3 and 4 respond to non-painful warmth, TRP melastatin 8 is activated by non-painful cool temperatures, while TRP ankyrin (TRPA) 1 is activated by painful cold. The thermal thresholds of many thermo-TRPs are known to be modulated by extracellular mediators, released by tissue damage or inflammation, such as bradykinin, PG and growth factors. There have been intensive efforts recently to develop antagonists of thermo-TRP channels, particularly of the noxious thermal sensors TRPV1 and TRPA1. Blockers of these channels are likely to have therapeutic uses as novel analgesics, but may also cause unacceptable side effects. Controlling the modulation of thermo-TRPs by inflammatory mediators may be a useful alternative strategy in developing novel analgesics.
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Affiliation(s)
- Laura Vay
- Department of Pharmacology, University of Cambridge, Cambridge, UK
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15
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New strategies to develop novel pain therapies: addressing thermoreceptors from different points of view. Pharmaceuticals (Basel) 2011; 5:16-48. [PMID: 24288041 PMCID: PMC3763626 DOI: 10.3390/ph5010016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 12/16/2011] [Accepted: 12/21/2011] [Indexed: 01/23/2023] Open
Abstract
One approach to develop successful pain therapies is the modulation of dysfunctional ion channels that contribute to the detection of thermal, mechanical and chemical painful stimuli. These ion channels, known as thermoTRPs, promote the sensitization and activation of primary sensory neurons known as nociceptors. Pharmacological blockade and genetic deletion of thermoTRP have validated these channels as therapeutic targets for pain intervention. Several thermoTRP modulators have progressed towards clinical development, although most failed because of the appearance of unpredicted side effects. Thus, there is yet a need to develop novel channel modulators with improved therapeutic index. Here, we review the current state-of-the art and illustrate new pharmacological paradigms based on TRPV1 that include: (i) the identification of activity-dependent modulators of this thermoTRP channel; (ii) the design of allosteric modulators that interfere with protein-protein interaction involved in the functional coupling of stimulus sensing and gate opening; and (iii) the development of compounds that abrogate the inflammation-mediated increase of receptor expression in the neuronal surface. These new sites of action represent novel strategies to modulate pathologically active TRPV1, while minimizing an effect on the TRPV1 subpopulation involved in physiological and protective roles, thus increasing their potential therapeutic use.
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16
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Jiang LH, Gamper N, Beech DJ. Properties and therapeutic potential of transient receptor potential channels with putative roles in adversity: focus on TRPC5, TRPM2 and TRPA1. Curr Drug Targets 2011; 12:724-36. [PMID: 21291387 PMCID: PMC3267159 DOI: 10.2174/138945011795378568] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Accepted: 06/28/2010] [Indexed: 01/13/2023]
Abstract
Mammals contain 28 genes encoding Transient Receptor Potential (TRP) proteins. The proteins assemble into cationic channels, often with calcium permeability. Important roles in physiology and disease have emerged and so there is interest in whether the channels might be suitable therapeutic drug targets. Here we review selected members of three subfamilies of mammalian TRP channel (TRPC5, TRPM2 and TRPA1) that show relevance to sensing of adversity by cells and biological systems. Summarized are the cellular and tissue distributions, general properties, endogenous modulators, protein partners, cellular and tissue functions, therapeutic potential, and pharmacology. TRPC5 is stimulated by receptor agonists and other factors that include lipids and metal ions; it heteromultimerises with other TRPC proteins and is involved in cell movement and anxiety control. TRPM2 is activated by hydrogen peroxide; it is implicated in stress-related inflammatory, vascular and neurodegenerative conditions. TRPA1 is stimulated by a wide range of irritants including mustard oil and nicotine but also, controversially, noxious cold and mechanical pressure; it is implicated in pain and inflammatory responses, including in the airways. The channels have in common that they show polymodal stimulation, have activities that are enhanced by redox factors, are permeable to calcium, and are facilitated by elevations of intracellular calcium. Developing inhibitors of the channels could lead to new agents for a variety of conditions: for example, suppressing unwanted tissue remodeling, inflammation, pain and anxiety, and addressing problems relating to asthma and stroke.
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Affiliation(s)
- L H Jiang
- Institute of Membrane & Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
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17
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Belvisi MG, Dubuis E, Birrell MA. Transient receptor potential A1 channels: insights into cough and airway inflammatory disease. Chest 2011; 140:1040-1047. [PMID: 21972382 DOI: 10.1378/chest.10-3327] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Cough is a common symptom of diseases such as asthma and COPD and also presents as a disease in its own right. Treatment options are limited; a recent meta-analysis concluded that over-the-counter remedies are ineffective, and there is increasing concern about their use in children. Transient receptor potential cation channel, subfamily A, member 1 (TRPA1) channels are nonselective cation channels that are activated by a range of natural products (eg, allyl isothiocyanate), a multitude of environmental irritants (eg, acrolein, which is present in air pollution, vehicle exhaust, and cigarette smoke), and inflammatory mediators (eg, cyclopentenone prostaglandins). TRPA1 is primarily expressed in small-diameter, nociceptive neurons where its activation probably contributes to the perception of noxious stimuli. Inhalational exposure to irritating gases, fumes, dusts, vapors, chemicals, and endogenous mediators can lead to the development of cough. The respiratory tract is innervated by primary sensory afferent nerves, which are activated by mechanical and chemical stimuli. Recent data suggest that activation of TRPA1 on these vagal sensory afferents by these irritant substances could lead to central reflexes, including dyspnea, changes in breathing pattern, and cough, which contribute to the symptoms and pathophysiology of respiratory diseases.
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Affiliation(s)
- Maria G Belvisi
- Respiratory Pharmacology, Airway Disease Section, National Heart and Lung Institute, Centre for Integrative Physiology and Pharmacology, Faculty of Medicine, Imperial College London, London; Respiratory Research Group, University of Manchester, Manchester, England.
| | - Eric Dubuis
- Respiratory Pharmacology, Airway Disease Section, National Heart and Lung Institute, Centre for Integrative Physiology and Pharmacology, Faculty of Medicine, Imperial College London, London
| | - Mark A Birrell
- Respiratory Pharmacology, Airway Disease Section, National Heart and Lung Institute, Centre for Integrative Physiology and Pharmacology, Faculty of Medicine, Imperial College London, London
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18
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Abstract
Cough is a troublesome symptom associated with many respiratory diseases. In some instances cough can become prolonged and excessive, and chronic cough of various aetiologies is a common presentation to specialist respiratory clinics. However, current treatment options are limited. Despite its importance, our understanding of the mechanisms that provoke cough is poor. Recent investigation has focused on the interaction between G-protein-coupled receptors and ion channels expressed on airway sensory nerves that are responsible for driving the cough reflex. In particular, the Transient Receptor Potential class of ion channels appears to play a major role as a regulator of the afferent arm of the cough reflex and could be involved in the heightened cough response observed in disease states. Current research investigating the pathogenesis of cough supports the development of TRP channel inhibitors as novel and selective treatment modalities.
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19
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TRPA1 ion channel in the spinal dorsal horn as a therapeutic target in central pain hypersensitivity and cutaneous neurogenic inflammation. Eur J Pharmacol 2011; 666:1-4. [DOI: 10.1016/j.ejphar.2011.05.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 05/02/2011] [Accepted: 05/11/2011] [Indexed: 01/22/2023]
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20
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Recent advances in the biology and medicinal chemistry of TRPA1. Future Med Chem 2011; 2:843-58. [PMID: 21426205 DOI: 10.4155/fmc.10.29] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The transient receptor potential cation channel, subfamily A, member 1 (TRPA1) is a nonselective cation channel that is highly expressed in small-diameter sensory neurons, where it functions as a polymodal receptor, responsible for detecting potentially harmful chemicals, mechanical forces and temperatures. TRPA1 is also activated and/or sensitized by multiple endogenous inflammatory mediators. As such, TRPA1 likely mediates the pain and neurogenic inflammation caused by exposure to reactive chemicals. In addition, it is also possible that this channel may mediate some of the symptoms of chronic inflammatory conditions such as asthma. We review recent advances in the biology of TRPA1 and summarize the evidence for TRPA1 as a therapeutic drug target. In addition, we provide an update on TRPA1 medicinal chemistry and the progress in the search for novel TRPA1 antagonists.
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21
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Valente P, Fernández-Carvajal A, Camprubí-Robles M, Gomis A, Quirce S, Viana F, Fernández-Ballester G, González-Ros JM, Belmonte C, Planells-Cases R, Ferrer-Montiel A. Membrane-tethered peptides patterned after the TRP domain (TRPducins) selectively inhibit TRPV1 channel activity. FASEB J 2011; 25:1628-40. [PMID: 21307333 DOI: 10.1096/fj.10-174433] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The transient receptor potential vanilloid 1 (TRPV1) channel is a thermosensory receptor implicated in diverse physiological and pathological processes. The TRP domain, a highly conserved region in the C terminus adjacent to the internal channel gate, is critical for subunit tetramerization and channel gating. Here, we show that cell-penetrating, membrane-anchored peptides patterned after this protein domain are moderate and selective TRPV1 antagonists both in vitro and in vivo, blocking receptor activity in intact rat primary sensory neurons and their peripheral axons with mean decline time of 30 min. The most potent lipopeptide, TRP-p5, blocked all modes of TRPV1 gating with micromolar efficacy (IC(50)<10 μM), without significantly affecting other thermoTRP channels. In contrast, its retrosequence or the corresponding sequences of other TRPV channels did not alter TRPV1 channel activity (IC(50)>100 μM). TRP-p5 did not affect the capsaicin sensitivity of the vanilloid receptor. Our data suggest that TRP-p5 interferes with protein-protein interactions at the level of the TRP domain that are essential for the "conformational" change that leads to gate opening. Therefore, these palmitoylated peptides, which we termed TRPducins, are noncompetitive, voltage-independent, sequence-specific TRPV1 blockers. Our findings indicate that TRPducin-like peptides may embody a novel molecular strategy that can be exploited to generate a selective pharmacological arsenal for the TRP superfamily of ion channels.
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Affiliation(s)
- Pierluigi Valente
- Instituto de Biología Molecular y Celular, Universidad Miguel Herna´ndez, Elche, Spain
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22
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Viana F. Chemosensory properties of the trigeminal system. ACS Chem Neurosci 2011; 2:38-50. [PMID: 22778855 PMCID: PMC3369707 DOI: 10.1021/cn100102c] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 12/14/2010] [Indexed: 11/28/2022] Open
Abstract
The capacity of cutaneous, including trigeminal endings, to detect chemicals is known as chemesthesis or cutaneous chemosensation. This sensory function involves the activation of nociceptor and thermoreceptor endings and has a protective or defensive function, as many of these substances are irritants or poisonous. However, humans have also developed a liking for the distinct sharpness or pungency of many foods, beverages, and spices following activation of the same sensory afferents. Our understanding of the cellular and molecular mechanisms of chemosensation in the trigeminal system has experienced enormous progress in the past decade, following the cloning and functional characterization of several ion channels activated by physical and chemical stimuli. This brief review attempts to summarize our current knowledge in this field, including a functional description of various sensory channels, especially TRP channels, involved in trigeminal chemosensitivy. Finally, some of these new findings are discussed in the context of the pathophysiology of trigeminal chemosensation, including pain, pruritus, migraine, cough, airway inflammation, and ophthalmic diseases.
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Affiliation(s)
- Félix Viana
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, 03550, San Juan de Alicante, Spain.
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23
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Abstract
Natural product ligands have contributed significantly to the deorphanisation of TRP ion channels. Furthermore, natural product ligands continue to provide valuable leads for the identification of ligands acting at "orphan" TRP channels. Additional naturally occurring modulators at TRP channels can be expected to be discovered in future, aiding in our understanding of not only their pharmacology and physiology, but also the therapeutic potential of this fascinating family of ion channels.
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Gijsen HJM, Berthelot D, Zaja M, Brône B, Geuens I, Mercken M. Analogues of morphanthridine and the tear gas dibenz[b,f][1,4]oxazepine (CR) as extremely potent activators of the human transient receptor potential ankyrin 1 (TRPA1) channel. J Med Chem 2010; 53:7011-20. [PMID: 20806939 DOI: 10.1021/jm100477n] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The TRPA1 channel can be considered as a key biological sensor to irritant chemicals. In this paper, the discovery of 11H-dibenz[b,e]azepines (morphanthridines) and dibenz[b,f][1,4]oxazepines is described as extremely potent agonists of the TRPA1 receptor. This has led to the discovery that most of the known tear gases are potent TRPA1 activators. The synthesis and biological activity of a number of substituted morphanthridines and dibenz[b,f][1,4]oxazepines have given insight into the SAR around this class of TRPA1 agonists, with EC(50) values ranging from 1 μM to 0.1 nM. Compounds 6 and 32 can be considered as the most potent TRPA1 agonists known to date, with 6 now being used successfully as a screening tool in the discovery of TRPA1 antagonists. The use of ligands such as 6 and 32 as pharmacological tools may contribute to the basic knowledge of the TRPA1 channel and advance the development of TRPA1 antagonists as potential treatment for conditions involving TRPA1 activation, including asthma and pain.
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Affiliation(s)
- Harrie J M Gijsen
- Medicinal Chemistry Department, Johnson & Johnson Pharmaceutical Research & Development, Turnhoutseweg 30, 2340 Beerse, Belgium.
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Dissociation of μ- and δ-opioid inhibition of glutamatergic synaptic transmission in superficial dorsal horn. Mol Pain 2010; 6:71. [PMID: 20977770 PMCID: PMC2987996 DOI: 10.1186/1744-8069-6-71] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 10/26/2010] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND There is anatomical and behavioural evidence that μ- and δ-opioid receptors modulate distinct nociceptive modalities within the superficial dorsal horn. The aim of the present study was to examine whether μ- and δ-opioid receptor activation differentially modulates TRP sensitive inputs to neurons within the superficial dorsal horn. To do this, whole cell patch clamp recordings were made from lamina I - II neurons in rat spinal cord slices in vitro to examine the effect of opioids on TRP agonist-enhanced glutamatergic spontaneous miniature excitatory postsynaptic currents (EPSCs). RESULTS Under basal conditions the μ-opioid agonist DAMGO (3 μM) reduced the rate of miniature EPSCs in 68% of neurons, while the δ- and κ-opioid agonists deltorphin-II (300 nM) and U69593 (300 nM) did so in 13 - 17% of neurons tested. The TRP agonists menthol (400 μM) and icilin (100 μM) both produced a Ca2+-dependent increase in miniature EPSC rate which was unaffected by the voltage dependent calcium channel (VDCC) blocker Cd2+. The proportion of neurons in which deltorphin-II reduced the miniature EPSC rate was enhanced in the presence of icilin (83%), but not menthol (0%). By contrast, the proportion of DAMGO and U69593 responders was unaltered in the presence of menthol (57%, 0%), or icilin (57%, 17%). CONCLUSIONS These findings demonstrate that δ-opioid receptor activation selectively inhibits inputs activated by icilin, whereas μ-opioid receptor activation has a more widespread effect on synaptic inputs to neurons in the superficial dorsal horn. These findings suggest that δ-opioids may provide a novel analgesic approach for specific, TRPA1-like mediated pain modalities.
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26
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Baraldi PG, Preti D, Materazzi S, Geppetti P. Transient receptor potential ankyrin 1 (TRPA1) channel as emerging target for novel analgesics and anti-inflammatory agents. J Med Chem 2010; 53:5085-107. [PMID: 20356305 DOI: 10.1021/jm100062h] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Pier Giovanni Baraldi
- Department of Pharmaceutical Sciences, Ferrara University, Via Fossato di Mortara 17-19, 44100 Ferrara, Italy.
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27
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Bakthavatchalam R, Kimball SD. Modulators of Transient Receptor Potential Ion Channels. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2010. [DOI: 10.1016/s0065-7743(10)45003-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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