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Guo CR, Zhang ZZ, Zhou X, Sun MY, Li TT, Lei YT, Gao YH, Li QQ, Yue CX, Gao Y, Lin YY, Hao CY, Li CZ, Cao P, Zhu MX, Rong MQ, Wang WH, Yu Y. Chronic cough relief by allosteric modulation of P2X3 without taste disturbance. Nat Commun 2023; 14:5844. [PMID: 37730705 PMCID: PMC10511716 DOI: 10.1038/s41467-023-41495-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 09/06/2023] [Indexed: 09/22/2023] Open
Abstract
P2X receptors are cation channels that sense extracellular ATP. Many therapeutic candidates targeting P2X receptors have begun clinical trials or acquired approval for the treatment of refractory chronic cough (RCC) and other disorders. However, the present negative allosteric modulation of P2X receptors is primarily limited to the central pocket or the site below the left flipper domain. Here, we uncover a mechanism of allosteric regulation of P2X3 in the inner pocket of the head domain (IP-HD), and show that the antitussive effects of quercetin and PSFL2915 (our nM-affinity P2X3 inhibitor optimized based on quercetin) on male mice and guinea pigs were achieved by preventing allosteric changes of IP-HD in P2X3. While being therapeutically comparable to the newly licensed P2X3 RCC drug gefapixant, quercetin and PSFL2915 do not have an adverse effect on taste as gefapixant does. Thus, allosteric modulation of P2X3 via IP-HD may be a druggable strategy to alleviate RCC.
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Affiliation(s)
- Chang-Run Guo
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 211198, China
| | - Zhong-Zhe Zhang
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Xing Zhou
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Meng-Yang Sun
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Tian-Tian Li
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Yun-Tao Lei
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Yu-Hao Gao
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Qing-Quan Li
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Chen-Xi Yue
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Yu Gao
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Yi-Yu Lin
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Cui-Yun Hao
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Chang-Zhu Li
- State Key Laboratory of Utilization of Woody Oil Resource, Hunan Academy of Forestry, Changsha, Hunan, 410004, China
| | - Peng Cao
- Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, 77030, USA
| | - Ming-Qiang Rong
- The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.
| | - Wen-Hui Wang
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China.
| | - Ye Yu
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China.
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 211198, China.
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2
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Al Yacoub ON, Awwad HO, Zhang Y, Standifer KM. Therapeutic potential of nociceptin/orphanin FQ peptide (NOP) receptor modulators for treatment of traumatic brain injury, traumatic stress, and their co-morbidities. Pharmacol Ther 2022; 231:107982. [PMID: 34480968 DOI: 10.1016/j.pharmthera.2021.107982] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/12/2021] [Accepted: 08/12/2021] [Indexed: 12/22/2022]
Abstract
The nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor is a member of the opioid receptor superfamily with N/OFQ as its endogenous agonist. Wide expression of the NOP receptor and N/OFQ, both centrally and peripherally, and their ability to modulate several biological functions has led to development of NOP receptor modulators by pharmaceutical companies as therapeutics, based upon their efficacy in preclinical models of pain, anxiety, depression, Parkinson's disease, and substance abuse. Both posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI) are debilitating conditions that significantly affect the quality of life of millions of people around the world. PTSD is often a consequence of TBI, and, especially for those deployed to, working and/or living in a war zone or are first responders, they are comorbid. PTSD and TBI share common symptoms, and negatively influence outcomes as comorbidities of the other. Unfortunately, a lack of effective therapies or therapeutic agents limits the long term quality of life for either TBI or PTSD patients. Ours, and other groups, demonstrated that PTSD and TBI preclinical models elicit changes in the N/OFQ-NOP receptor system, and that administration of NOP receptor ligands alleviated some of the neurobiological and behavioral changes induced by brain injury and/or traumatic stress exposure. Here we review the past and most recent progress on understanding the role of the N/OFQ-NOP receptor system in PTSD and TBI neurological and behavioral sequelae. There is still more to understand about this neuropeptide system in both PTSD and TBI, but current findings warrant further examination of the potential utility of NOP modulators as therapeutics for these disorders and their co-morbidities. We advocate the development of standards for common data elements (CDE) reporting for preclinical PTSD studies, similar to current preclinical TBI CDEs. That would provide for more standardized data collection and reporting to improve reproducibility, interpretation and data sharing across studies.
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Affiliation(s)
- Omar N Al Yacoub
- Department of Pharmaceutical Sciences, University of Oklahoma College of Pharmacy, OUHSC, Oklahoma City, OK 73117, United States of America
| | - Hibah O Awwad
- Department of Pharmaceutical Sciences, University of Oklahoma College of Pharmacy, OUHSC, Oklahoma City, OK 73117, United States of America
| | - Yong Zhang
- Department of Pharmaceutical Sciences, University of Oklahoma College of Pharmacy, OUHSC, Oklahoma City, OK 73117, United States of America
| | - Kelly M Standifer
- Department of Pharmaceutical Sciences, University of Oklahoma College of Pharmacy, OUHSC, Oklahoma City, OK 73117, United States of America.
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3
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Pacifico S, Albanese V, Illuminati D, Marzola E, Fabbri M, Ferrari F, Holanda VAD, Sturaro C, Malfacini D, Ruzza C, Trapella C, Preti D, Lo Cascio E, Arcovito A, Della Longa S, Marangoni M, Fattori D, Nassini R, Calò G, Guerrini R. Novel Mixed NOP/Opioid Receptor Peptide Agonists. J Med Chem 2021; 64:6656-6669. [PMID: 33998786 PMCID: PMC8279409 DOI: 10.1021/acs.jmedchem.0c02062] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
![]()
The nociceptin/orphanin FQ (N/OFQ)/N/OFQ receptor (NOP) system
controls different biological functions including pain and cough reflex.
Mixed NOP/opioid receptor agonists elicit similar effects to strong
opioids but with reduced side effects. In this work, 31 peptides with
the general sequence [Tyr/Dmt1,Xaa5]N/OFQ(1-13)-NH2 were synthesized and pharmacologically characterized for
their action at human recombinant NOP/opioid receptors. The best results
in terms of NOP versus mu opioid receptor potency were obtained by
substituting both Tyr1 and Thr5 at the N-terminal
portion of N/OFQ(1-13)-NH2 with the noncanonical amino
acid Dmt. [Dmt1,5]N/OFQ(1-13)-NH2 has been identified
as the most potent dual NOP/mu receptor peptide agonist so far described.
Experimental data have been complemented by in silico studies to shed light on the molecular mechanisms by which the peptide
binds the active form of the mu receptor. Finally, the compound exerted
antitussive effects in an in vivo model of cough.
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Affiliation(s)
- Salvatore Pacifico
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy
| | - Valentina Albanese
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy
| | - Davide Illuminati
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy
| | - Erika Marzola
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy
| | - Martina Fabbri
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy
| | - Federica Ferrari
- Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Via Fossato di Mortara 17/19, Ferrara 44121, Italy
| | - Victor A D Holanda
- Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Via Fossato di Mortara 17/19, Ferrara 44121, Italy
| | - Chiara Sturaro
- Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Via Fossato di Mortara 17/19, Ferrara 44121, Italy
| | - Davide Malfacini
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Largo Meneghetti 2, Padova 35131, Italy
| | - Chiara Ruzza
- Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Via Fossato di Mortara 17/19, Ferrara 44121, Italy.,Technopole of Ferrara, LTTA Laboratory for Advanced Therapies, via Fossato di Mortara 70, Ferrara 44121, Italy
| | - Claudio Trapella
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy.,Technopole of Ferrara, LTTA Laboratory for Advanced Therapies, via Fossato di Mortara 70, Ferrara 44121, Italy
| | - Delia Preti
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy
| | - Ettore Lo Cascio
- Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, Largo F. Vito 1, Roma 00168, Italy
| | - Alessandro Arcovito
- Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, Largo F. Vito 1, Roma 00168, Italy.,Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo F. Vito 1, Roma 00168, Italy
| | - Stefano Della Longa
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Pza S. Tommasi 1, L'Aquila 67100, Italy
| | - Martina Marangoni
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Viale Pieraccini, 6, Florence 50139, Italy
| | - Davide Fattori
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Viale Pieraccini, 6, Florence 50139, Italy
| | - Romina Nassini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Viale Pieraccini, 6, Florence 50139, Italy
| | - Girolamo Calò
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Largo Meneghetti 2, Padova 35131, Italy
| | - Remo Guerrini
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy.,Technopole of Ferrara, LTTA Laboratory for Advanced Therapies, via Fossato di Mortara 70, Ferrara 44121, Italy
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4
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Deng Z, Zhou W, Sun J, Li C, Zhong B, Lai K. IFN-γ Enhances the Cough Reflex Sensitivity via Calcium Influx in Vagal Sensory Neurons. Am J Respir Crit Care Med 2019; 198:868-879. [PMID: 29672123 DOI: 10.1164/rccm.201709-1813oc] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Cough hypersensitivity syndrome is often triggered by a viral infection. The viral infection might trigger cough hypersensitivity via increasing the release of IFN-γ from T lymphocytes in the lung. OBJECTIVES To investigate effects of IFN-γ on the vagal sensory neurons and the cough reflex. METHODS Effects of IFN-γ on the cough reflex were investigated in guinea pigs. Cellular immunofluorescence imaging, calcium imaging, and patch clamp techniques were used to study effects of IFN-γ in primary cultured rat vagal sensory neurons. MEASUREMENTS AND MAIN RESULTS Intratracheal instillation of IFN-γ enhanced the cough response to citric acid in vivo. IFN-γ significantly increased levels of phosphorylated signal transducer and activator of transcription-1 but not phosphorylated transient receptor potential vanilloid 1 in vitro. Not only did IFN-γ enhance the response of neurons to capsaicin and electric stimulation, but also it directly induced Ca2+ influx, membrane depolarization, and action potentials in neurons via the Janus kinase, protein kinase A, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid pathways. However, IFN-γ did not elicit Ca2+ release from the endoplasmic reticulum via the phospholipase C pathway. Although IFN-γ-induced action potentials were suppressed by Ca2+ influx inhibitors, IFN-γ-induced Ca2+ influx was not altered by an inhibitor of rapid sodium channels. CONCLUSIONS The membrane potential in vagal sensory neurons may be depolarized by IFN-γ-induced Ca2+ influx. The depolarization of membrane potentials may enhance the cough reflex sensitivity and cause action potentials. IFN-γ may be a new target for treating cough hypersensitivity syndrome and postviral cough.
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Affiliation(s)
- Zheng Deng
- 1 State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,2 School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, China; and
| | - Wenliang Zhou
- 3 School of Life Science, Sun Yat-sen University, Guangzhou, China
| | - Jiayang Sun
- 1 State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Chenhui Li
- 1 State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Bonian Zhong
- 1 State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Kefang Lai
- 1 State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
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5
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D'Agostino B, Sgambato M, Esposito R, Spaziano G. N/OFQ-NOP System and Airways. Handb Exp Pharmacol 2019; 254:313-322. [PMID: 30725285 DOI: 10.1007/164_2018_202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Asthma is a heterogeneous chronic inflammatory disease of the airways. The most prevalent form is atopic asthma, which is initiated by the exposure to (inhaled) allergens. Intermittent attacks of breathlessness, airways hyperresponsiveness, wheezing, coughing, and resultant allergen-specific immune responses characterize the disease. Nociceptin/OFQ-NOP receptor system is able to combine anti-hyperresponsiveness and immunomodulatory actions. In particular, N/OFQ is able to inhibit airways microvascular leakage and bronchoconstriction through a presynaptic and non-opioid mechanism of action that blocks tachykinin release. Moreover, it also acts on allergenic sensitization because it is able to modulate the immune response that triggers the development of airway hyperresponsiveness through an interaction on cell membranes of dendritic cells (DCs) that are generally responsible to start and sustain allergic T helper 2 (TH2)-cell responses to inhaled allergens in asthma. In asthmatic patients, sputum showed elevated N/OFQ levels that are related to increased eosinophil counts. The addition of exogenous N/OFQ in sputum obtained from patients with severe asthma attenuated eosinophils migration and release of inflammatory mediators. These observations confirmed that elevated endogenous N/OFQ levels in asthmatic sputum were lower than the ones required to exert beneficial effects, suggesting that supplementation with exogenous N/OFQ may need. In conclusion, the innovative role of N/OFQ in counteracting airways inflammation/hyperresponsiveness opens new potential targets/strategies in asthma treatment.
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Affiliation(s)
- Bruno D'Agostino
- Department of Experimental Medicine, Section of Pharmacology L. Donatelli, University of Campania "L. Vanvitelli", Naples, Italy.
| | - Manuela Sgambato
- Department of Experimental Medicine, Section of Pharmacology L. Donatelli, University of Campania "L. Vanvitelli", Naples, Italy
| | - Renata Esposito
- Department of Experimental Medicine, Section of Pharmacology L. Donatelli, University of Campania "L. Vanvitelli", Naples, Italy
| | - Giuseppe Spaziano
- Department of Experimental Medicine, Section of Pharmacology L. Donatelli, University of Campania "L. Vanvitelli", Naples, Italy
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6
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Zaveri NT. Nociceptin Opioid Receptor (NOP) as a Therapeutic Target: Progress in Translation from Preclinical Research to Clinical Utility. J Med Chem 2016; 59:7011-28. [PMID: 26878436 DOI: 10.1021/acs.jmedchem.5b01499] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In the two decades since the discovery of the nociceptin opioid receptor (NOP) and its ligand, nociceptin/orphaninFQ (N/OFQ), steady progress has been achieved in understanding the pharmacology of this fourth opioid receptor/peptide system, aided by genetic and pharmacologic approaches. This research spawned an explosion of small-molecule NOP receptor ligands from discovery programs in major pharmaceutical companies. NOP agonists have been investigated for their efficacy in preclinical models of anxiety, cough, substance abuse, pain (spinal and peripheral), and urinary incontinence, whereas NOP antagonists have been investigated for treatment of pain, depression, and motor symptoms in Parkinson's disease. Translation of preclinical findings into the clinic is guided by PET and receptor occupancy studies, particularly for NOP antagonists. Recent progress in preclinical NOP research suggests that NOP agonists may have clinical utility for pain treatment and substance abuse pharmacotherapy. This review discusses the progress toward validating the NOP-N/OFQ system as a therapeutic target.
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Affiliation(s)
- Nurulain T Zaveri
- Astraea Therapeutics , 320 Logue Avenue, Suite 142, Mountain View, California 94043, United States
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7
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Bonvini SJ, Birrell MA, Smith JA, Belvisi MG. Targeting TRP channels for chronic cough: from bench to bedside. Naunyn Schmiedebergs Arch Pharmacol 2015; 388:401-20. [PMID: 25572384 DOI: 10.1007/s00210-014-1082-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 12/16/2014] [Indexed: 12/24/2022]
Abstract
Cough is currently the most common reason for patients to visit a primary care physician in the UK, yet it remains an unmet medical need. Current therapies have limited efficacy or have potentially dangerous side effects. Under normal circumstances, cough is a protective reflex to clear the lungs of harmful particles; however, in disease, cough can become excessive, dramatically impacting patients' lives. In many cases, this condition is linked to inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD), but can also be refractory to treatment and idiopathic in nature. Therefore, there is an urgent need to develop therapies, and targeting the sensory afferent arm of the reflex which initiates the cough reflex may uncover novel therapeutic targets. The cough reflex is initiated following activation of ion channels present on vagal sensory afferents. These ion channels include the transient receptor potential (TRP) family of cation-selective ion channels which act as cellular sensors and respond to changes in the external environment. Many direct activators of TRP channels, including arachidonic acid derivatives, a lowered airway pH, changes in temperature, and altered airway osmolarity are present in the diseased airway where responses to challenge agents which activate airway sensory nerve activity are known to be enhanced. Furthermore, the expression of some TRP channels is increased in airway disease. Together, this makes them promising targets for the treatment of chronic cough. This review will cover the current understanding of the role of the TRP family of ion channels in the activation of airway sensory nerves and cough, focusing on four members, transient receptor potential vanilloid (TRPV) 1, transient receptor potential ankyrin (TRPA) 1, TRPV4, and transient receptor potential melastatin (TRPM) 8 as these represent the channels where most information has been gathered with relevance to the airways. We will describe recent data and highlight the possible therapeutic utility of specific TRP channel antagonists as antitussives in the clinic.
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Affiliation(s)
- Sara J Bonvini
- Respiratory Pharmacology Group, Airway Disease Section, National Heart & Lung Institute, Imperial College, Exhibition Road, London, SW7 2AZ, UK
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8
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Kunda PE, Cavicchia JC, Acosta CG. Lipopolysaccharides and trophic factors regulate the LPS receptor complex in nodose and trigeminal neurons. Neuroscience 2014; 280:60-72. [PMID: 25218806 DOI: 10.1016/j.neuroscience.2014.08.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 08/12/2014] [Accepted: 08/26/2014] [Indexed: 12/21/2022]
Abstract
Binding of bacterial lipopolysaccharides (LPS) to toll-like receptor 4 (TLR4) triggers an innate immunoresponse associated with pain and inflammation. The expression, and to a greater extent the regulation of TLR4 and its auxiliary proteins (myeloid differentiation protein 1 (MD1), myeloid differentiation protein 2 (MD2) and cluster of differentiation 14 (CD14)), are both poorly understood in trigeminal and nodose neurons. We used a combination of Western blotting, semi-quantitative polymerase chain reaction (PCR), pharmacological manipulation and immunohistochemistry. The expression pattern and regulation by LPS and trophic factors of TLR4/MD2/CD14 and radioprotective protein of 105kDa (RP105)/MD1 were determined in neonatal trigeminal and nodose mice neurons. We found that all these proteins were expressed in both trigeminal and nodose neurons. The trophic factors Artemin and nerve growth factor (NGF) up-regulated MD2 and RP105 mRNA levels in trigeminal neurons. In nodose neurons the trophic factors brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF) up-regulated MD1 and RP105 mRNA levels. Also we observed that in both neuronal types LPS acutely (within 20 min) down-regulated CD14 and MD2 mRNAs. In addition, LPS increased significantly the proportion of trigeminal and nodose neurons expressing nociceptin/orphanin FQ in culture probably acting via TLR4/MD2. Although the exact mechanisms underlying the regulation by trophic factors and LPS require further elucidation, the findings of this study indicate that LPS acts through its archetypical receptor in trigeminal and nodose neurons.
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Affiliation(s)
- P E Kunda
- Instituto de Investigaciones en Ciencias de la Salud (INICSA), Facultad de Ciencias Medicas, Universidad Nacional de Córdoba, 5000 Córdoba, Argentina
| | - J C Cavicchia
- Instituto de Histología y Embriología de Mendoza (IHEM), Facultad de Medicina, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
| | - C G Acosta
- Instituto de Histología y Embriología de Mendoza (IHEM), Facultad de Medicina, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina.
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9
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Dicpinigaitis PV, Morice AH, Birring SS, McGarvey L, Smith JA, Canning BJ, Page CP. Antitussive drugs--past, present, and future. Pharmacol Rev 2014; 66:468-512. [PMID: 24671376 PMCID: PMC11060423 DOI: 10.1124/pr.111.005116] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Cough remains a serious unmet clinical problem, both as a symptom of a range of other conditions such as asthma, chronic obstructive pulmonary disease, gastroesophageal reflux, and as a problem in its own right in patients with chronic cough of unknown origin. This article reviews our current understanding of the pathogenesis of cough and the hypertussive state characterizing a number of diseases as well as reviewing the evidence for the different classes of antitussive drug currently in clinical use. For completeness, the review also discusses a number of major drug classes often clinically used to treat cough but that are not generally classified as antitussive drugs. We also reviewed a number of drug classes in various stages of development as antitussive drugs. Perhaps surprising for drugs used to treat such a common symptom, there is a paucity of well-controlled clinical studies documenting evidence for the use of many of the drug classes in use today, particularly those available over the counter. Nonetheless, there has been a considerable increase in our understanding of the cough reflex over the last decade that has led to a number of promising new targets for antitussive drugs being identified and thus giving some hope of new drugs being available in the not too distant future for the treatment of this often debilitating symptom.
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Affiliation(s)
- P V Dicpinigaitis
- King's College London, Franklin Wilkins Building, 100 Stamford St., London, SE1 9NH, UK.
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10
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Gavioli EC, Calo' G. Nociceptin/orphanin FQ receptor antagonists as innovative antidepressant drugs. Pharmacol Ther 2013; 140:10-25. [PMID: 23711793 DOI: 10.1016/j.pharmthera.2013.05.008] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 12/21/2022]
Abstract
Nociceptin/orphanin FQ (N/OFQ) and its receptor (NOP) were identified in the mid 90s as a novel peptidergic system structurally related to opioids. A growing body of preclinical evidence suggests that blockade of NOP receptors evokes antidepressant-like actions. These have been explored using a range of compounds (peptide and non peptide antagonists), across different species (rat and mouse) and assays (behavioral despair and chronic mild stress) suggesting a robust and consistent antidepressant-like effect. Moreover, rats and mice knockout for the NOP receptor gene display an antidepressant-like phenotype in behavioral despair assays. Electrophysiological, immunohistochemical and neurochemical studies point to an important role played by monoaminergic systems, particularly 5-HTergic, in mediating the antidepressant-like properties of NOP antagonists. However other putative mechanisms of action, including modulation of the CRF system, circadian rhythm and a possible neuroendocrine-immune control might be involved. A close relationship between the N/OFQ-NOP receptor system and stress responses is well described in the literature. Stressful situations also alter endocrine, behavioral and neurochemical parameters in rats and chronic administration of a NOP antagonist restored these alterations. Interestingly, clinical findings showed that plasma N/OFQ levels were significantly altered in major and post-partum depression, and bipolar disease patients. Collectively, data in the literature support the notion that blockade of NOP receptor signaling could be a novel and interesting strategy for the development of innovative antidepressants.
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Affiliation(s)
- Elaine Cristina Gavioli
- Department of Biophysics and Pharmacology, Federal University of Rio Grande do Norte, 59078-970 Natal-RN, Brazil.
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11
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Sullo N, Roviezzo F, Matteis M, Ianaro A, Calò G, Guerrini R, De Gruttola L, Spaziano G, Cirino G, Rossi F, D'Agostino B. Nociceptin/orphanin FQ receptor activation decreases the airway hyperresponsiveness induced by allergen in sensitized mice. Am J Physiol Lung Cell Mol Physiol 2013; 304:L657-64. [PMID: 23502511 DOI: 10.1152/ajplung.00358.2012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Several studies suggest that the N/OFQ (nociceptin/orphanin FQ)-NOP (N/OFQ peptide) receptor pathway is involved in airway physiology. We previously demonstrated a modulation of the endogenous N/OFQ levels in allergen-sensitized mice. Here, we investigated the effects of NOP receptor activation in allergen sensitization using a murine model of allergen-induced airway hyperresponsiveness (AHR). BALB/c mice were intraperitoneally treated with the NOP receptor agonist UFP-112, either during the sensitization phase (30 min before ovalbumin administration) or at the end of sensitization process (15 min before bronchopulmonary reactivity evaluation). At day 21 from the first allergen exposure, bronchopulmonary reactivity and total and differential cell count in bronchoalveolar lavage fluid were evaluated. In a separate set of experiments cell proliferation in lymphocytes, cytokine levels, IgE serum levels, and the effect of UFP-112 on IL-13-induced AHR were evaluated. Pretreatment with UFP-112, during the sensitization phase, caused a significant reduction in allergen-induced AHR and total cell lung infiltration. No effect on allergen-induced AHR was observed when the treatment was performed at the end of sensitization process, on tissues harvested from OVA-sensitized mice and on IL-13-induced AHR. The in vitro proliferative response of lymphocytes was significantly reduced by pretreatment during the sensitization phase with UFP-112. This effect was paralleled by a significant modulation of cytokine secretion in pulmonary tissues and lymphocytes. In conclusion, we demonstrated a role for the NOP receptor and N/OFQ pathway in the AHR induced by allergen, probably through a modulation of the immune response that triggers the development of AHR that involves pro- and anti-inflammatory cytokines.
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Affiliation(s)
- Nikol Sullo
- Department of Experimental Medicine-Section of Pharmacology, Faculty of Medicine and Surgery, 2nd University of Naples, 80136 Naples, Italy
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12
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Spina D, Page CP. Regulating cough through modulation of sensory nerve function in the airways. Pulm Pharmacol Ther 2013; 26:486-90. [PMID: 23524012 DOI: 10.1016/j.pupt.2013.03.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 03/07/2013] [Accepted: 03/12/2013] [Indexed: 01/12/2023]
Abstract
Whilst local anaesthetics when applied directly to laryngeal nerves or topically to the lung can suppress cough, their chronic use is constrained because of dose limiting side effects. However, the effectiveness of local anaesthetics suggests that selectivity targeting nerves in the airway may provide novel approaches for the treatment of cough in the future. There is a considerable wealth of evidence showing that there are different afferent nerve subtypes in the airways. Traditionally C-fibres have been the focus of much research in the cough field since the stimulation of these afferents by capsaicin is able to elicit cough in guinea-pigs and in man, and drugs targeting various proteins expressed in these nerves (e.g. mu-opioid, NOP1, TRPV1, sodium channels) have been shown to be anti-tussive in preclinical models of cough. However, interest in Aδ fibres has increased recently in light of the discovery of a specific cough receptor in the guinea-pig that is provoked by citric acid and punctate stimulation, but not capsaicin and which has been anatomically linked to Aδ fibres. There is also some evidence that as a result of inflammation in the airways, Aδ fibres can begin to express neuropeptides and TRPV1 receptors so that they can become responsive to endogenous activators of this ion channel and to irritants like capsaicin. Consequently, there is considerable interest in targeting either one or both afferent nerve types for the treatment of chronic cough. However, to date the translation of preclinical studies into man has largely been disappointing and certainly there is a need for better preclinical models in this field. There also remain many challenges to overcome at a clinical level, such as what patient group(s) should be used to assess anti-tussive drugs and whether the use of irritants that induce cough in healthy volunteers (such as citric acid or capsaicin) is of any value in the assessment of novel anti-tussive drugs. The development of several continuous monitoring methodologies for measuring cough will hopefully allow better evaluation of treatments in patients with chronic cough. Nonetheless, cough remains a major unmet clinical need in respiratory medicine where new drugs are urgently required.
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Affiliation(s)
- D Spina
- The Sackler Institute of Pulmonary Pharmacology, Institute of Pharmaceutical Science, King's College London, London SE1 9NH, UK.
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13
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Grace MS, Dubuis E, Birrell MA, Belvisi MG. Pre-clinical studies in cough research: role of Transient Receptor Potential (TRP) channels. Pulm Pharmacol Ther 2013; 26:498-507. [PMID: 23474212 PMCID: PMC3763377 DOI: 10.1016/j.pupt.2013.02.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/19/2013] [Accepted: 02/24/2013] [Indexed: 02/08/2023]
Abstract
Cough is a protective reflex and defence mechanism in healthy individuals, which helps clear excessive secretions and foreign material from the lungs. Cough often presents as the first and most persistent symptom of many respiratory diseases and some non-respiratory disorders, but can also be idiopathic, and is a common respiratory complaint for which medical attention is sought. Chronic cough of various aetiologies is a regular presentation to specialist respiratory clinics, and is reported as a troublesome symptom by a significant proportion of the population. Despite this, the treatment options for cough are limited. The lack of effective anti-tussives likely stems from our incomplete understanding of how the tussive reflex is mediated. However, research over the last decade has begun to shed some light on the mechanisms which provoke cough, and may ultimately provide us with better anti-tussive therapies. This review will focus on the in vitro and in vivo models that are currently used to further our understanding of the sensory innervation of the respiratory tract, and how these nerves are involved in controlling the cough response. Central to this are the Transient Receptor Potential (TRP) ion channels, a family of polymodal receptors that can be activated by such diverse stimuli as chemicals, temperature, osmotic stress, and mechanical perturbation. These ion channels are thought to be molecular pain integrators and targets for novel analgesic agents for the treatment of various pain disorders but some are also being developed as anti-tussives.
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Affiliation(s)
- Megan S Grace
- Respiratory Pharmacology, Pharmacology & Toxicology Section, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, Exhibition Road, London SW7 2AZ, UK
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14
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Singh SR, Sullo N, D'Agostino B, Brightling CE, Lambert DG. The effects of nociceptin peptide (N/OFQ)-receptor (NOP) system activation in the airways. Peptides 2013; 39:36-46. [PMID: 23123316 DOI: 10.1016/j.peptides.2012.10.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 10/17/2012] [Accepted: 10/22/2012] [Indexed: 11/20/2022]
Abstract
The heptadecapeptide nociceptin/orphanin FQ (N/OFQ) is the endogenous ligand for the N/OFQ peptide (NOP) receptor. It is cleaved from a larger precursor identified as prepronociceptin (ppN/OFQ). NOP is a member of the seven transmembrane-spanning G-protein coupled receptor (GPCR) family. ppN/OFQ and NOP receptors are widely distributed in different human tissues. Asthma is a complex heterogeneous disease characterized by variable airflow obstruction, bronchial hyper-responsiveness and chronic airway inflammation. Limited therapeutic effectiveness of currently available asthma therapies warrants identification of new drug compounds. Evidence from animal studies suggests that N/OFQ modulates airway contraction and inflammation. Interestingly up regulation of the N/OFQ-NOP system reduces airway hyper-responsiveness. In contrast, inflammatory cells central to the inflammatory response in asthma may be both sources of N/OFQ and respond to NOP activation. Hence paradoxical dysregulation of the N/OFQ-NOP system may potentially play an important role in regulating airway inflammation and airway tone. To date there is no data on N/OFQ-NOP expression in the human airways. Therefore, the potential role of N/OFQ-NOP system in asthma is unknown. This review focuses on its physiological effects within airways and potential value as a novel asthma therapy.
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Affiliation(s)
- Shailendra R Singh
- Department of Cardiovascular Sciences (Pharmacology and Therapeutics Group), Division of Anaesthesia, Critical Care and Pain Management, University of Leicester, Leicester Royal Infirmary, Leicester, UK.
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15
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Abstract
This review dissects the complex human cough reflex and suggests hypotheses about the evolutionary basis for the reflex. A mechanosensory-induced cough reflex conveys through branches of myelinated Aδ nerve fibers is not chemically reactive (i.e., capsaicin, bradykinin); possibly, its evolution is to prevent the harmful effects of aspiration of gastric or particulate contents into the lungs. This became necessary as the larynx moves closer to the opening of the esophagus as human ancestors adapt phonation over olfaction beginning less than 10 million years ago. The second type of cough reflex, a chemosensory type, is carried by unmyelinated C fibers. Supposedly, its origin dates back when prehistoric humans began living in close proximity to each other and were at risk for infectious respiratory diseases or irritant-induced lung injury. The mechanism for the latter type of cough is analogous to induced pain after tissue injury; and, it is controlled by the identical transient receptor potential vanilloid cation channel (TRPV1). The airways do not normally manifest nociceptive pain from a stimulus but the only consistent response that capsaicin and lung inflammation provoke in healthy human airways is cough. TRPA1, another excitatory ion channel, has been referred to as the "irritant receptor" and its activation also induces cough. For both types of cough, the motor responses are identical and via coordinated, precisely-timed and sequential respiratory events orchestrated by complex neuromuscular networking of the diaphragm, chest and abdominal respiratory muscles, the glottis and parts of the brain.
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Affiliation(s)
- Stuart M Brooks
- Colleges of Public Health and Medicine, University of South Florida, Tampa, Florida.
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16
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McLeod RL, Tulshian DB, Sadeh J. Where are the new cough treatments: a debriefing of recent clinical proof-of-concept trials with the NOP agonist SCH 486757. Pharmacology 2011; 88:50-4. [PMID: 21757975 DOI: 10.1159/000328782] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Accepted: 04/15/2011] [Indexed: 11/19/2022]
Abstract
Cough continues to be one of the top reasons why patients seek medical attention from health care providers. The prescription antitussive market is dominated by opioids, such as codeine that produces inconsistent efficacy and is often accompanied by significant side effect liabilities. Consequently, cough represents an unmet medical need and an underserved market. Yet, against the backdrop of increasing cough research, the development of novel treatments has been exceptionally challenging with dextromethorphan being the last US drug approved for cough almost a half century ago. We support the position that an unambiguous and actionable 'road map' that clearly delineates the pathway forward for new cough suppressants from basic research to and beyond clinical proof-of-concept studies will be an important aspect for future success of this pharmacological class of drug. Pivotal to the establishment of such a road map will be the review of lessons learned from antitussive agents that have been recently progressed to proof-of-concept trials. In the present commentary, we briefly discuss observations and challenges pertaining to SCH 486757, a selective orally active NOP agonist that has recently advanced to human antitussive testing.
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Affiliation(s)
- Robbie L McLeod
- Bone, Respiratory, Immunology and Dermatology, Merck Research Laboratories, Kenilworth, NJ 07033-0539, USA.
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17
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Mazzone SB, McGovern AE, Cole LJ, Farrell MJ. Central nervous system control of cough: pharmacological implications. Curr Opin Pharmacol 2011; 11:265-71. [DOI: 10.1016/j.coph.2011.05.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 05/19/2011] [Indexed: 02/06/2023]
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18
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Hayashi S, Nakata E, Morita A, Mizuno K, Yamamura K, Kato A, Ohashi K. Discovery of {1-[4-(2-{hexahydropyrrolo[3,4-c]pyrrol-2(1H)-yl}-1H-benzimidazol-1-yl)piperidin-1-yl]cyclooctyl}methanol, systemically potent novel non-peptide agonist of nociceptin/orphanin FQ receptor as analgesic for the treatment of neuropathic pain: Design, synthesis, and structure–activity relationships. Bioorg Med Chem 2010; 18:7675-99. [DOI: 10.1016/j.bmc.2010.07.034] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 07/14/2010] [Accepted: 07/15/2010] [Indexed: 10/19/2022]
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19
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Undem BJ, Carr MJ. Targeting primary afferent nerves for novel antitussive therapy. Chest 2010; 137:177-84. [PMID: 20051402 DOI: 10.1378/chest.09-1960] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The best available data support the hypothesis that there are at least two types of vagal nerves responsible for initiating coughing reflexes. One type of nerve conducts action potentials in the A-range and is characterized by rapidly adapting responses to mechanical probing or acidification of the large airway epithelium. Stimulation of these nerves can evoke cough in unconscious experimental animals and humans. These nerves are important in immediate cough evoked by aspiration and as such perform a critical role in airway defense. The other type of primary afferent nerve involved in cough is the vagal C-fiber. Inhalation of selective C-fiber stimulants leads to cough only in conscious animals. In clinical studies, inhalation of a low concentration of a C-fiber stimulant causes an irritating, itchy urge-to-cough sensation that mimics the urge-to-cough sensations associated with respiratory tract infection, post-infection, gastroesophageal reflux disorders, and inflammatory airway diseases. Here we discuss the recent advances in sensory neurobiology that allow for the targeting of vagal C-fibers for novel antitussive therapy. No attempts are made to be all-inclusive with respect to the numerous possible molecular targets being considered to accomplish this goal. Rather, two general strategies are discussed: decreasing generator potential amplitude and decreasing the efficiency by which a generator potential evokes action-potential discharge. For the first category we focus on two targets, transient receptor potential vanilloid 1 and transient receptor potential A1. For the latter category we focus on recent advances in voltage-gated sodium (Na(V)) channel biology.
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Affiliation(s)
- Bradley J Undem
- Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA.
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20
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Pharmacological profile of the NOP agonist and cough suppressing agent SCH 486757 (8-[Bis(2-Chlorophenyl)Methyl]-3-(2-Pyrimidinyl)-8-Azabicyclo[3.2.1]Octan-3-Ol) in preclinical models. Eur J Pharmacol 2009; 630:112-20. [PMID: 20006596 DOI: 10.1016/j.ejphar.2009.12.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 11/19/2009] [Accepted: 12/03/2009] [Indexed: 10/20/2022]
Abstract
We describe the pharmacological and pharmacokinetic profiles of SCH 486757, a nociceptin/orphanin FQ peptide (NOP) receptor agonist that has recently entered human clinical trials for cough. SCH 486757 selectively binds human NOP receptor (K(i)=4.6+/-0.61nM) over classical opioid receptors. In a guinea pig capsaicin cough model, SCH 486757 (0.01-1mg/kg) suppressed cough at 2, 4, and 6h post oral administration with a maximum efficacy occurring at 4h equivalent to codeine, hydrocodone, dextromethorphan and baclofen. The antitussive effects of SCH 486757 (3.0mg/kg, p.o.) was blocked by the NOP receptor antagonist J113397 (12mg/kg, i.p.) but not by naltrexone (10mg/kg, p.o.). SCH 486757 does not produce tolerance to its antitussive activity after a 5-day BID dosing regimen. After acute and chronic dosing paradigms, SCH 486757 (1mg/kg) inhibited capsaicin-evoked coughing by 46+/-9% and 40+/-11%, respectively. In a feline mechanically-evoked cough model, SCH 486757 produces a maximum inhibition of cough and expiratory abdominal electromyogram amplitude of 59 and 61%, respectively. SCH 486757 did not significantly affect inspiratory electromyogram amplitude. We examined the abuse potential of SCH 486757 (10mg/kg, p.o.) in a rat conditioned place preference procedure which is sensitive to classical drugs of abuse, such as amphetamine and morphine. SCH 486757 was without effect in this model. Finally, SCH 486757 displays a good oral pharmacokinetic profile in the guinea pig, rat and dog. We conclude that SCH 486757 has a favorable antitussive profile in preclinical animal models.
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21
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Canning BJ. Central regulation of the cough reflex: therapeutic implications. Pulm Pharmacol Ther 2009; 22:75-81. [PMID: 19284972 DOI: 10.1016/j.pupt.2009.01.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Accepted: 01/08/2009] [Indexed: 01/12/2023]
Abstract
In many species including humans, antagonists of NMDA-type glutamate receptors such as dextromethorphan, when used at sufficient doses, have been found to be relatively safe and effective antitussives. Similarly, now in five different species (guinea pigs, rabbits, cats, dogs and pigs), neurokinin receptor antagonists have also proven to be safe and effective antitussive agents. Both of these classes of drugs act centrally to prevent cough. A brief review of what is known about the central encoding of cough is presented, as are the advantages of centrally acting antitussives. Also discussed are new insights into cough and NMDA receptor signaling that may lead to the development of more effective antitussive agents with limited side effects and broad application in treating cough associated with a variety of aetiologies.
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22
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Abstract
Cough is a persistent symptom of many inflammatory airways' diseases. Cough is mediated by receptors sited on sensory nerves and then through vagal afferent pathways, which terminate in the brainstem respiratory centre. Cough is often described as an unmet clinical need. Opioids are the only prescription-based antitussives currently available in the UK. They possess limited efficacy and exhibit serious unwanted side effects, such as physical dependence, sedation, respiratory depression and gastrointestinal symptoms. There are three classical opioid receptors: the mu, kappa and delta receptors. Peripheral opioid receptors are sited on sensory nerves innervating the airways. A greater understanding of the role of the peripheral and centrally sited opioid receptors is necessary to allow the development of targeted treatments for cough. Because of the limited efficacy and the side-effect profile of the opioids, potential new treatments are sought to alleviate cough. One class of compounds that is currently under examination is the cannabinoids. Like the opioids, cannabinoids have peripheral and centrally sited receptors and also suffer from the blight of unwanted centrally mediated side effects such as sedation, cognitive dysfunction, tachycardia and psychotropic effects. Two cannabinoid receptors have been identified, the CB(1) and CB(2) receptors, and their distribution varies throughout the peripheral and central nervous system. Encouragingly, early studies with these compounds suggest that it may be possible to separate their antitussive activity from their centrally mediated side effects, with CB(2) agonists showing potential as putative new treatments for cough. In this chapter, we describe the opioid and cannabinoid receptors, their distribution and the effects they mediate. Moreover, we highlight their potential advantages and disadvantages in the treatment of cough.
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Affiliation(s)
- M G Belvisi
- Respiratory Pharmacology, Airway Diseases, National Heart & Lung Institute, Imperial College, Guy Scadding Building, Dovehouse Street, London SW3 6LY, UK.
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23
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Abstract
Following systemic administration, centrally acting antitussive drugs are generally assumed to act in the brainstem to inhibit cough. However, recent work in humans has raised the possibility of suprapontine sites of action for cough suppressants. For drugs that may act in the brainstem, the specific locations, types of neurones affected, and receptor specificities of the compounds represent important issues regarding their cough-suppressant actions. Two medullary areas that have received the most attention regarding the actions of antitussive drugs are the nucleus of the tractus solitarius (NTS) and the caudal ventrolateral respiratory column. Studies that have implicated these two medullary areas have employed both microinjection and in vitro recording methods to control the location of action of the antitussive drugs. Other brainstem regions contain neurones that participate in the production of cough and could represent potential sites of action of antitussive drugs. These regions include the raphe nuclei, pontine nuclei, and rostral ventrolateral medulla. Specific receptor subtypes have been associated with the suppression of cough at central sites, including 5-HT1A, opioid (mu, kappa, and delta), GABA-B, tachykinin neurokinin-1 (NK-1) and neurokinin-2, non-opioid (NOP-1), cannabinoid, dopaminergic, and sigma receptors. Aside from tachykinin NK-1 receptors in the NTS, relatively little is known regarding the receptor specificity of putative antitussive drugs in particular brainstem regions. Our understanding of the mechanisms of action of antitussive drugs would be significantly advanced by further work in this area.
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Affiliation(s)
- D C Bolser
- Department of Physiological Sciences, University of Florida, College of Veterinary Medicine, Gainesville, FL 32610-0144, USA.
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24
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Chung KF. Clinical cough VI: the need for new therapies for cough: disease-specific and symptom-related antitussives. Handb Exp Pharmacol 2009:343-368. [PMID: 18825350 DOI: 10.1007/978-3-540-79842-2_18] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Cough is a common symptom that can be self-limiting or persistent. Ideally, treatment of the underlying cause(s) of cough with specific treatments should eliminate cough. This approach may not be successful if no cause can be established or if the treatment of the cause fails. Suppression of cough may be disease-specific or symptom-related. There has been a long tradition in acute cough usually due to upper respiratory tract infections to use symptom-related antitussives. In chronic cough, suppression of cough may be achieved by disease-specific therapies, but in many patients it may be necessary to use symptomatic antitussives. The efficacy of some over-the-counter symptomatic antitussives is often no better than that of a placebo. Currently available cough suppressants include the centrally acting opioids such as morphine, codeine, pholcodeine, and dextromethorphan. Early studies reported success in reducing cough in patients with chronic bronchitis or chronic obstructive pulmonary disease (COPD); however, a carefully conducted blinded controlled study showed no effect of codeine on cough of COPD. Success with these cough suppressants may be achieved at high doses that are associated with side effects. A slow-release preparation of morphine has been shown to have some degree of efficacy, but this should be reserved for the most severe chronic cough patient, and for patients with terminal cancer who may also benefit from its analgesic effects. There are case reports of the success of centrally acting drugs such as amitriptyline, paroxetine, gabapentin, and carbamezepine in chronic cough. New agents derived from basic research such as new opioids such as nociceptin or antagonists of transient receptor potential vanniloid-1 may turn out to have antitussive effects. Efficacy of symptomatic cough suppressants must be tested in double-blind randomized trials using validated measures of cough in patients with chronic cough not responding to specific treatments. Patients with chronic cough need effective antitussives that could be used either on demand or on a long-term basis.
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Affiliation(s)
- K F Chung
- National Heart and Lung Institute, Imperial College London, London, UK.
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25
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Abstract
Several airway afferent nerve subtypes have been implicated in coughing. These include bronchopulmonary C-fibers, rapidly adapting airway mechanoreceptors and touch-sensitive tracheal Adelta-fibers (also called cough receptors). Although the last two afferent nerve subtypes are primarily sensitive to mechanical stimuli, all can be acted upon by one or more different chemical stimuli. In this review we catalogue the chemical agents that stimulate and/or modulate the activity of the airway afferent nerves involved in cough, and describe the specific mechanisms involved in these effects. In addition, we describe the mechanisms of action of a number of chemical inhibitors of these afferent nerve subtypes, and attempt to relate this information to the regulation of coughing in health and disease.
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Affiliation(s)
- S B Mazzone
- School of Biomedical Sciences, The University of Queensland, St. Lucia QLD 4072, Australia.
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26
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The nociceptin/orphanin FQ receptor: a target with broad therapeutic potential. Nat Rev Drug Discov 2008; 7:694-710. [DOI: 10.1038/nrd2572] [Citation(s) in RCA: 284] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Abstract
This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, United States.
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28
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Barnes PJ. The problem of cough and development of novel antitussives. Pulm Pharmacol Ther 2007; 20:416-22. [PMID: 17189707 DOI: 10.1016/j.pupt.2006.11.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 11/06/2006] [Indexed: 01/08/2023]
Abstract
Cough is a very common clinical symptom and current therapies are largely ineffective, indicating a major unmet medial need. There is a pressing need to develop novel and safe antitussive therapies. This is likely to arise from better understanding of the sensory nerves involved in cough and the signalling pathways that are activated. A major therapeutic target should be sensitization of the cough reflex which is a feature of patients with both acute (virally induced) cough and chronic cough, including chronic idiopathic cough. Studies on human cough mechanisms are limited. There are several novel therapeutic approaches that are currently being explored. Perhaps the most promising drugs are transient receptor potential vanilloid-1 (TRPV(1)) antagonists, selective cannabinoid agonists (CB2 agonists), maxi-K channel openers and P2X3 antagonists. New cough therapies may target airway nerve sensitization and may best be delivered as inhalers to minimize any systemic effects. Understanding the intercellular signalling pathways involved in nociception may lead to novel drugs, such as p38 mitogen-activated protein (MAP) kinase inhibitors, being used in the treatment of cough in the future. It is also likely that several novel treatments that are developed as analgesics will also prove to be beneficial in the treatment of cough.
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Affiliation(s)
- Peter J Barnes
- Department of Thoracic Medicine, National Heart and Lung Institute, Dovehouse Street, London SW3 6LY, UK.
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29
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Abstract
Coughing can be both voluntarily induced and involuntarily initiated by activation of vagal afferent nerves innervating the airways and lungs. Centrally, cough is regulated at the level of the brainstem through integration of vagal afferent nerve input by relay neurones in the nucleus tractus solitarius (nTS). Projections to and from the nTS add further complexity to cough regulation, as do the profound influences of psychological and social factors known to regulate cough. Peripherally, both neuronal and non-neuronal elements in the airways regulate the excitability of the vagal afferent nerve terminals regulating cough. These multiple levels of integration and encoding of the cough reflex may render this defensive respiratory response highly susceptible to modulation both by disease processes and through therapeutic intervention.
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Affiliation(s)
- Brendan J Canning
- Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA.
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30
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Kollarik M, Ru F, Undem BJ. Acid-sensitive vagal sensory pathways and cough. Pulm Pharmacol Ther 2006; 20:402-11. [PMID: 17289409 PMCID: PMC2577168 DOI: 10.1016/j.pupt.2006.11.010] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Accepted: 11/28/2006] [Indexed: 02/03/2023]
Abstract
Acid is an important mediator in the pathogenesis of cough. Inhalation of exogenous acid triggers cough and endogenous acid may contribute to cough in respiratory diseases. Acid directly stimulates vagal bronchopulmonary sensory nerves that regulate the cough reflex. Consistent with their putative role in defence against aspiration and inhaled irritants, Adelta-fibre nociceptors in the large airways are most efficiently stimulated by rapid acidification. In contrast, acid-sensitive properties of the C-fibre nociceptors allow for continuous monitoring of pH which is likely important in inflammation. Acid is also the single most important mediator in the pathogenesis of cough due to gastro-oesophageal reflux (GOR). The cough pathways can be sensitized by the sensory inputs from the oesophagus. This sensitization is likely mediated by a subset of the vagal oesophageal sensory nerves distinguished by discriminative responsiveness to noxious stimuli (nociceptors). The receptors underlying acid sensitivity of vagal sensory nerves are incompletely understood. The role of TRPV1 has been established but the roles of acid-sensing ion channels (ASIC) and other receptors await more definitive investigation. Here, we provide a brief overview of the cough-related acid-sensitive sensory pathways and discuss the mechanisms of acid sensitivity.
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Affiliation(s)
- Marian Kollarik
- The Johns Hopkins School of Medicine, Johns Hopkins Asthma and Allergy Center, Baltimore, MD 21224, USA.
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Abstract
The induction of action potentials in airway sensory nerves relies on events leading to the opening of cation channels in the nerve terminal membrane and subsequent membrane depolarization. If the membrane depolarization is of sufficient rate and amplitude, action potential initiation will occur. The action potentials are then conducted to the central nervous system, leading to the initiation of various sensations and cardiorespiratory reflexes. Triggering events in airway sensory nerves include mechanical perturbation, inflammatory mediators, pH, temperature, and osmolarity acting through a variety of ionotropic and metabotropic receptors. Action potential initiation can be modulated (positively or negatively) through independent mechanisms caused mainly by autacoids and other metabotropic receptor ligands. Finally, gene expression of sensory nerves can be altered in adult mammals. This neuroplasticity can change the function of sensory nerves and likely involve both neurotrophin and use-dependent mechanisms. Here we provide a brief overview of some of the transduction mechanisms underlying these events.
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