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Gu QD, Joe DS, Gilbert CA. Activation of bitter taste receptors in pulmonary nociceptors sensitizes TRPV1 channels through the PLC and PKC signaling pathway. Am J Physiol Lung Cell Mol Physiol 2017; 312:L326-L333. [PMID: 28062485 DOI: 10.1152/ajplung.00468.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/03/2017] [Accepted: 01/03/2017] [Indexed: 11/22/2022] Open
Abstract
Bitter taste receptors (T2Rs), a G protein-coupled receptor family capable of detecting numerous bitter-tasting compounds, have recently been shown to be expressed and play diverse roles in many extraoral tissues. Here we report the functional expression of T2Rs in rat pulmonary sensory neurons. In anesthetized spontaneously breathing rats, intratracheal instillation of T2R agonist chloroquine (10 mM, 0.1 ml) significantly augmented chemoreflexes evoked by right-atrial injection of capsaicin, a specific activator for transient receptor potential vanilloid receptor 1 (TRPV1), whereas intravenous infusion of chloroquine failed to significantly affect capsaicin-evoked reflexes. In patch-clamp recordings with isolated rat vagal pulmonary sensory neurons, pretreatment with chloroquine (1-1,000 µM, 90 s) concentration dependently potentiated capsaicin-induced TRPV1-mediated inward currents. Preincubating with diphenitol and denatonium (1 mM, 90 s), two other T2R activators, also enhanced capsaicin currents in these neurons but to a lesser extent. The sensitizing effect of chloroquine was effectively prevented by the phospholipase C inhibitor U73122 (1 µM) or by the protein kinase C inhibitor chelerythrine (10 µM). In summary, our study showed that activation of T2Rs augments capsaicin-evoked TRPV1 responses in rat pulmonary nociceptors through the phospholipase C and protein kinase C signaling pathway.
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Affiliation(s)
- Qihai David Gu
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, Georgia
| | - Deanna S Joe
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, Georgia
| | - Carolyn A Gilbert
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, Georgia
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52
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Lu P, Zhang CH, Lifshitz LM, ZhuGe R. Extraoral bitter taste receptors in health and disease. J Gen Physiol 2017; 149:181-197. [PMID: 28053191 PMCID: PMC5299619 DOI: 10.1085/jgp.201611637] [Citation(s) in RCA: 136] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 10/06/2016] [Accepted: 12/19/2016] [Indexed: 12/24/2022] Open
Abstract
Bitter taste receptors (TAS2Rs or T2Rs) belong to the superfamily of seven-transmembrane G protein-coupled receptors, which are the targets of >50% of drugs currently on the market. Canonically, T2Rs are located in taste buds of the tongue, where they initiate bitter taste perception. However, accumulating evidence indicates that T2Rs are widely expressed throughout the body and mediate diverse nontasting roles through various specialized mechanisms. It has also become apparent that T2Rs and their polymorphisms are associated with human disorders. In this review, we summarize the physiological and pathophysiological roles that extraoral T2Rs play in processes as diverse as innate immunity and reproduction, and the major challenges in this emerging field.
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Affiliation(s)
- Ping Lu
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605
| | - Cheng-Hai Zhang
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605
| | - Lawrence M Lifshitz
- Biomedical Imaging Group, University of Massachusetts Medical School, Worcester, MA 01605.,Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605
| | - Ronghua ZhuGe
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605 .,Biomedical Imaging Group, University of Massachusetts Medical School, Worcester, MA 01605
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53
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Kook JH, Kim HK, Kim HJ, Kim KW, Kim TH, Kang KR, Oh DJ, Lee SH. Increased expression of bitter taste receptors in human allergic nasal mucosa and their contribution to the shrinkage of human nasal mucosa. Clin Exp Allergy 2016; 46:584-601. [PMID: 26931803 DOI: 10.1111/cea.12727] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 01/19/2016] [Accepted: 02/07/2016] [Indexed: 12/01/2022]
Abstract
OBJECTIVE Bitter taste receptors (TAS2Rs) are expressed in the extraoral tissues, where they possess various physiological functions. This study is to characterize TAS2Rs expression in normal and allergic nasal mucosa and analyse nasal symptom after challenge with bitter tastes to evaluate their pathophysiological function in normal and allergic nasal mucosa. METHODS The expression levels of TAS2Rs (TAS2R4, 5, 7, 10, 14, 39, and 43) in nasal mucosa were investigated by real-time PCR, Western blot, and immunohistochemistry. The expression levels of TAS2Rs and Ca(2+) imaging in cultured epithelial cells were measured after stimulation with type 2 cytokines (IL-4, IL-5, and IL-13) or bitter tastes. Nasal symptoms in control subjects and allergic rhinitis patients using visual analogue score and acoustic rhinometry were evaluated before and after stimulation with bitter tastes. Vascular diameter of rat nasal septum was measured before and after treatment with bitter tastes. RESULTS TAS2Rs tested here were expressed in nasal mucosa where they were commonly distributed in superficial epithelium, submucosal glands, and endothelium. Their expression levels are increased in allergic nasal mucosa and up-regulated in cultured epithelial cells simulated with type 2 cytokines. After treatment with bitter tastes, intracellular Ca(2+) signalling was increased in cultured epithelial cells, and vascular constriction was found in rat nasal septum. Increased nasal patency was observed in human nasal mucosa without pain or sneezing. CONCLUSION AND CLINICAL RELEVANCE TAS2Rs are constitutively expressed in human nasal mucosa and their expression levels are increased in allergic nasal mucosa, where they could potentially contribute to shrinkage of normal and allergic nasal mucosa.
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Affiliation(s)
- J H Kook
- Department of Otorhinolaryngology-Head & Neck Surgery, College of Medicine, Hallym University, ChunCheon, South Korea
| | - H K Kim
- Department of Otorhinolaryngology-Head & Neck Surgery, College of Medicine, Korea University, Seoul, South Korea
| | - H J Kim
- College of Medicine, Korea University, Seoul, South Korea
| | - K W Kim
- College of Medicine, Korea University, Seoul, South Korea
| | - T H Kim
- Department of Otorhinolaryngology-Head & Neck Surgery, College of Medicine, Korea University, Seoul, South Korea
| | - K R Kang
- Department of Otorhinolaryngology-Head & Neck Surgery, College of Medicine, Korea University, Seoul, South Korea
| | - D J Oh
- Department of Otorhinolaryngology-Head & Neck Surgery, College of Medicine, Korea University, Seoul, South Korea
| | - S H Lee
- Department of Otorhinolaryngology-Head & Neck Surgery, College of Medicine, Korea University, Seoul, South Korea
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54
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Wang Y, Lu Y, Luo M, Shi X, Pan Y, Zeng H, Deng L. Evaluation of pharmacological relaxation effect of the natural product naringin on in vitro cultured airway smooth muscle cells and in vivo ovalbumin-induced asthma Balb/c mice. Biomed Rep 2016; 5:715-722. [PMID: 28101344 DOI: 10.3892/br.2016.797] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 09/29/2016] [Indexed: 12/23/2022] Open
Abstract
Asthma has become a common chronic respiratory disease worldwide and its prevalence is predicted to continue increasing in the next decade, particularly in developing countries. A key component in asthma therapy is to alleviate the excessive bronchial airway narrowing ultimately due to airway smooth muscle contraction, which is often facilitated by a smooth muscle relaxant, such as the β2-adrenergic agonists. Recently, bitter taste receptor (TAS2R) agonists, including saccharin and chloroquine, have been found to potently relax the airway smooth muscle cells (ASMCs) via intracellular Ca2+ signaling. This inspires a great interest in screening the vast resource of natural bitter substances for potential bronchodilatory drugs. In the present study, the relaxation effect of naringin, a compound extracted from common grapefruit, on ASMCs cultured in vitro or bronchial airways of Balb/c mice in vivo was evaluated. The results demonstrated that, when exposed to increasing doses of naringin (0.125, 0.25, 0.5 and 1.0 mM), the traction force generated by the cultured ASMCs decreased progressively, while the intracellular calcium flux signaling in the ASMCs increased. When inhaled at increasing doses (15, 30 and 60 µg), naringin also dose-dependently reduced the bronchial airway resistance of the normal and ovalbumin-induced asthma Balb/c mice in response to challenge with methacholine. In conclusion, these findings indicate that naringin was able to effectively relax murine ASMCs in vitro and in vivo, thus suggesting that it is a promising drug agent to be further investigated in the development of novel bronchodilators for the treatment of asthma.
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Affiliation(s)
- Yue Wang
- Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164, P.R. China; School of Nursing, Changzhou University, Changzhou, Jiangsu 213164, P.R. China; School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu 213164, P.R. China
| | - Yun Lu
- Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164, P.R. China; School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu 213164, P.R. China
| | - Mingzhi Luo
- Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164, P.R. China
| | - Xiaohao Shi
- Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164, P.R. China
| | - Yan Pan
- Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164, P.R. China
| | - Huilong Zeng
- Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164, P.R. China; School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu 213164, P.R. China
| | - Linhong Deng
- Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164, P.R. China; School of Nursing, Changzhou University, Changzhou, Jiangsu 213164, P.R. China; School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu 213164, P.R. China
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Ortiz JL, Ortiz A, Milara J, Armengot M, Sanz C, Compañ D, Morcillo E, Cortijo J. Evaluation of Mucociliary Clearance by Three Dimension Micro-CT-SPECT in Guinea Pig: Role of Bitter Taste Agonists. PLoS One 2016; 11:e0164399. [PMID: 27723827 PMCID: PMC5056690 DOI: 10.1371/journal.pone.0164399] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 09/23/2016] [Indexed: 12/15/2022] Open
Abstract
Different image techniques have been used to analyze mucociliary clearance (MCC) in humans, but current small animal MCC analysis using in vivo imaging has not been well defined. Bitter taste receptor (T2R) agonists increase ciliary beat frequency (CBF) and cause bronchodilation but their effects in vivo are not well understood. This work analyzes in vivo nasal and bronchial MCC in guinea pig animals using three dimension (3D) micro-CT-SPECT images and evaluates the effect of T2R agonists. Intranasal macroaggreggates of albumin-Technetium 99 metastable (MAA-Tc99m) and lung nebulized Tc99m albumin nanocolloids were used to analyze the effect of T2R agonists on nasal and bronchial MCC respectively, using 3D micro-CT-SPECT in guinea pig. MAA-Tc99m showed a nasal mucociliary transport rate of 0.36 mm/min that was increased in presence of T2R agonist to 0.66 mm/min. Tc99m albumin nanocolloids were homogeneously distributed in the lung of guinea pig and cleared with time-dependence through the bronchi and trachea of guinea pig. T2R agonist increased bronchial MCC of Tc99m albumin nanocolloids. T2R agonists increased CBF in human nasal ciliated cells in vitro and induced bronchodilation in human bronchi ex vivo. In summary, T2R agonists increase MCC in vivo as assessed by 3D micro-CT-SPECT analysis.
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Affiliation(s)
- Jose Luis Ortiz
- Department of Pharmacology, Faculty of Medicine, University of Valencia, Valencia, Spain
| | - Amparo Ortiz
- Department of Pharmacology, Faculty of Medicine, University of Valencia, Valencia, Spain
| | - Javier Milara
- Jaume I University, faculty of Medicine, Castellón, Spain
- Department of Pharmacy, University General Hospital Consortium, Valencia, Spain
- CIBERES, Health Institute Carlos III, Valencia, Spain
- * E-mail:
| | - Miguel Armengot
- Rhinology Unit, University General Hospital Consortium, Valencia, Spain
- Department of Surgery, Faculty of Medicine, University of Valencia, Valencia, Spain
| | - Celia Sanz
- Department of Pharmacology, Faculty of Medicine, University of Valencia, Valencia, Spain
- Jaume I University, faculty of Medicine, Castellón, Spain
| | - Desamparados Compañ
- Pathological Anatomy Department, Hospital Clínico Universitario of Valencia, Valencia, Spain
| | - Esteban Morcillo
- Department of Pharmacology, Faculty of Medicine, University of Valencia, Valencia, Spain
- CIBERES, Health Institute Carlos III, Valencia, Spain
| | - Julio Cortijo
- Department of Pharmacology, Faculty of Medicine, University of Valencia, Valencia, Spain
- CIBERES, Health Institute Carlos III, Valencia, Spain
- Teaching and Research Unit, University General Hospital Consortium, Valencia, Spain
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Larsson OJ, Manson ML, Starkhammar M, Fuchs B, Adner M, Kumlien Georén S, Cardell LO. The TLR7 agonist imiquimod induces bronchodilation via a nonneuronal TLR7-independent mechanism: a possible role for quinoline in airway dilation. Am J Physiol Lung Cell Mol Physiol 2016; 310:L1121-9. [PMID: 27084847 DOI: 10.1152/ajplung.00288.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 04/07/2016] [Indexed: 11/22/2022] Open
Abstract
Toll-like receptor (TLR) 7 agonists are known to reduce allergic airway inflammation. Their recently reported ability to rapidly relax airways has further increased their interest in the treatment of pulmonary disease. However, the mechanisms behind this effect are not fully understood. The present study, therefore, aimed to determine whether airway smooth muscle (ASM)-dependent mechanisms could be identified. TLR7 agonists were added to guinea pig airways following precontraction with carbachol in vitro or histamine in vivo. Pharmacological inhibitors were used to dissect conventional pathways of bronchodilation; tetrodotoxin was used or bilateral vagotomy was performed to assess neuronal involvement. Human ASM cells (HASMCs) were employed to determine the effect of TLR7 agonists on intracellular Ca(2+) ([Ca(2+)]i) mobilization. The well-established TLR7 agonist imiquimod rapidly relaxed precontracted airways in vitro and in vivo. This relaxation was demonstrated to be independent of nitric oxide, carbon monoxide, and cAMP signaling, as well as neuronal activity. A limited role for prostanoids could be detected. Imiquimod induced [Ca(2+)]i release from endoplasmic reticulum stores in HASMCs, inhibiting histamine-induced [Ca(2+)]i The TLR7 antagonist IRS661 failed to inhibit relaxation, and the structurally dissimilar agonist CL264 did not relax airways or inhibit [Ca(2+)]i This study shows that imiquimod acts directly on ASM to induce bronchorelaxation, via a TLR7-independent release of [Ca(2+)]i The effect is paralleled by other bronchorelaxant compounds, like chloroquine, which, like imiquimod, but unlike CL264, contains the chemical structure quinoline. Compounds with quinoline moieties may be of interest in the development of multifunctional drugs to treat pulmonary disease.
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Affiliation(s)
- Olivia J Larsson
- Division of ENT Diseases, CLINTEC, Karolinska Institutet, Stockholm, Sweden
| | - Martijn L Manson
- Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden; and Institute for Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Magnus Starkhammar
- Division of ENT Diseases, CLINTEC, Karolinska Institutet, Stockholm, Sweden; Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden; and
| | - Barbara Fuchs
- Division of ENT Diseases, CLINTEC, Karolinska Institutet, Stockholm, Sweden
| | - Mikael Adner
- Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden; and Institute for Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Susanna Kumlien Georén
- Division of ENT Diseases, CLINTEC, Karolinska Institutet, Stockholm, Sweden; Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden; and
| | - Lars-Olaf Cardell
- Division of ENT Diseases, CLINTEC, Karolinska Institutet, Stockholm, Sweden; Department of ENT Disease, Karolinska University Hospital, Stockholm, Sweden;
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57
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Avau B, Depoortere I. The bitter truth about bitter taste receptors: beyond sensing bitter in the oral cavity. Acta Physiol (Oxf) 2016; 216:407-20. [PMID: 26493384 DOI: 10.1111/apha.12621] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 09/28/2015] [Accepted: 10/14/2015] [Indexed: 11/26/2022]
Abstract
The bitter taste receptor (TAS2R)-family of G-protein-coupled receptors has been identified on the tongue as detectors of bitter taste over a decade ago. In the last few years, they have been discovered in an ever growing number of extra-oral tissues, including the airways, the gut, the brain and even the testis. In tissues that contact the exterior, protective functions for TAS2Rs have been proposed, in analogy to their function on the tongue as toxicity detector. However, TAS2Rs have also been found in internal organs, suggesting other roles for these receptors, perhaps involving as yet unidentified endogenous ligands. The current review gives an overview of the different proposed functions for TAS2Rs in tissues other than the oral cavity; from appetite regulation to the treatment of asthma, regulation of gastrointestinal motility and control of airway innate immunity.
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Affiliation(s)
- B. Avau
- Translational Research Center for Gastrointestinal Disorders (TARGID); Gut Peptide Research Lab; University of Leuven; Leuven Belgium
| | - I. Depoortere
- Translational Research Center for Gastrointestinal Disorders (TARGID); Gut Peptide Research Lab; University of Leuven; Leuven Belgium
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58
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Shaik FA, Singh N, Arakawa M, Duan K, Bhullar RP, Chelikani P. Bitter taste receptors: Extraoral roles in pathophysiology. Int J Biochem Cell Biol 2016; 77:197-204. [PMID: 27032752 DOI: 10.1016/j.biocel.2016.03.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 03/16/2016] [Accepted: 03/22/2016] [Indexed: 11/17/2022]
Abstract
Over the past decade tremendous progress has been made in understanding the functional role of bitter taste receptors (T2Rs) and bitter taste perception. This review will cover the recent advances made in identifying the role of T2Rs in pathophysiological states. T2Rs are widely expressed in various parts of human anatomy and have been shown to be involved in physiology of respiratory system, gastrointestinal tract and endocrine system. Empirical evidence has shown T2Rs to be an integral component of antimicrobial immune responses in upper respiratory tract infections. The studies on human airway smooth muscle cells have shown that a potent bitter tastant induced bronchodilatory effects mediated by bitter taste receptors. Clinical data suggests a role for T2R38 polymorphism in predisposition of individuals to chronic rhinosinusitis. The role of genetic variation in T2Rs and its impact on disease susceptibility have been investigated in various other disease risk factors such as alcohol dependence, head and neck cancers. Preliminary reports have demonstrated differential expression of functional T2Rs in breast cancer cell lines. Studies on the role of T2Rs in pathophysiology of diseases including chronic rhinosinusitis, asthma, cystic fibrosis, and cancer have been promising. However, research in this field is in its nascent stages, and more confirmatory studies on animal models and in clinical settings are required.
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Affiliation(s)
- Feroz Ahmed Shaik
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada; Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
| | - Nisha Singh
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada; Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
| | - Makoto Arakawa
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
| | - Kangmin Duan
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada; Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada
| | - Rajinder P Bhullar
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada
| | - Prashen Chelikani
- Manitoba Chemosensory Biology (MCSB) Research Group and Department of Oral Biology, University of Manitoba, Winnipeg, MB R3E 0W2, Canada; Children's Hospital Research Institute of Manitoba, Winnipeg, MB R3E 3P4, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB R3E 0W2, Canada.
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59
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Yoon SY, Shin ES, Park SY, Kim S, Kwon HS, Cho YS, Moon HB, Kim TB. Association between Polymorphisms in Bitter Taste Receptor Genes and Clinical Features in Korean Asthmatics. Respiration 2016; 91:141-50. [PMID: 26812163 DOI: 10.1159/000443796] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 12/30/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Bitter taste receptors (TAS2R) in human airway smooth muscle have recently been shown to have an important role in bronchodilation, together with β2-adrenergic receptors. OBJECT To evaluate the association between genetic variations in TAS2R and clinical features, including bronchodilator response and asthma control. METHOD We analyzed the association between single nucleotide polymorphisms (SNPs) of TAS2R10 and TAS2R14 and variables such as demographic data, atopy, duration of disease, and asthma control status, including variables such as asthma control test (ACT) score, percent predicted value of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio, as well as bronchodilator response (BDR), in 721 asthma patients in Korea. RESULT Three novel SNPs of 633G>A, 645C>A, and -79G>A in TAS2R10 and 3 known SNPs of -815T>C, -1267G>A, and -1897T>C in TAS2R14 were analyzed. Increased BDR was significantly associated with SNPs of -815T>C [OR (95% CI) = 1.88 (1.01-3.49), p = 0.04 ] [J Gen Physiol 2005;125:535-553; Am J Respir Cell Mol Biol 2010;42:373-3812], -1267A>G [OR (95% CI) = 2.07 (1.03-4.15), p = 0.04] and -1897T>C [OR (95% CI) = 3.05 (1.01-9.23), p = 0.04, in a dominant model, and OR = 1.91 (1.08-3.36), p = 0.02, in a codominant model] of the TAS2R14 gene. There was a significant association between -815T>C and a low mean ACT score [OR (95% CI) = 5.84 (1.94-17.61), p = 0.001]. In haplotype analysis, TAC, CAT, and TGT, or TG and CA haplotypes on TAS2R14 were significantly associated with increased BDR; CAT and CA haplotypes were significantly associated with a low ACT score. CONCLUSION Genetic variations in TAS2Rs may be valuable genetic markers to predict therapeutic response and outcomes in asthma. Further research in an independent cohort is needed.
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Affiliation(s)
- Sun-Young Yoon
- Division of Allergy and Clinical Immunology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
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60
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Sakai H, Sato K, Kai Y, Chiba Y, Narita M. Denatonium and 6- n-Propyl-2-thiouracil, Agonists of Bitter Taste Receptor, Inhibit Contraction of Various Types of Smooth Muscles in the Rat and Mouse. Biol Pharm Bull 2016; 39:33-41. [DOI: 10.1248/bpb.b15-00426] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Hiroyasu Sakai
- Department of Analytical Pathophysiology, Division of Pharmacy Professional Development and Research, Hoshi University
| | - Ken Sato
- Department of Analytical Pathophysiology, Division of Pharmacy Professional Development and Research, Hoshi University
| | - Yuki Kai
- Department of Analytical Pathophysiology, Division of Pharmacy Professional Development and Research, Hoshi University
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61
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Sharma P, Panebra A, Pera T, Tiegs BC, Hershfeld A, Kenyon LC, Deshpande DA. Antimitogenic effect of bitter taste receptor agonists on airway smooth muscle cells. Am J Physiol Lung Cell Mol Physiol 2015; 310:L365-76. [PMID: 26684251 DOI: 10.1152/ajplung.00373.2015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 12/15/2015] [Indexed: 02/05/2023] Open
Abstract
Airway remodeling is a hallmark feature of asthma and chronic obstructive pulmonary disease. Clinical studies and animal models have demonstrated increased airway smooth muscle (ASM) mass, and ASM thickness is correlated with severity of the disease. Current medications control inflammation and reverse airway obstruction effectively but have limited effect on remodeling. Recently we identified the expression of bitter taste receptors (TAS2R) on ASM cells, and activation with known TAS2R agonists resulted in ASM relaxation and bronchodilation. These studies suggest that TAS2R can be used as new therapeutic targets in the treatment of obstructive lung diseases. To further establish their effectiveness, in this study we aimed to determine the effects of TAS2R agonists on ASM growth and promitogenic signaling. Pretreatment of healthy and asthmatic human ASM cells with TAS2R agonists resulted in a dose-dependent inhibition of ASM proliferation. The antimitogenic effect of TAS2R ligands was not dependent on activation of protein kinase A, protein kinase C, or high/intermediate-conductance calcium-activated K(+) channels. Immunoblot analyses revealed that TAS2R agonists inhibit growth factor-activated protein kinase B phosphorylation without affecting the availability of phosphatidylinositol 3,4,5-trisphosphate, suggesting TAS2R agonists block signaling downstream of phosphatidylinositol 3-kinase. Furthermore, the antimitogenic effect of TAS2R agonists involved inhibition of induced transcription factors (activator protein-1, signal transducer and activator of transcription-3, E2 factor, nuclear factor of activated T cells) and inhibition of expression of multiple cell cycle regulatory genes, suggesting a direct inhibition of cell cycle progression. Collectively, these findings establish the antimitogenic effect of TAS2R agonists and identify a novel class of receptors and signaling pathways that can be targeted to reduce or prevent airway remodeling as well as bronchoconstriction in obstructive airway disease.
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Affiliation(s)
- Pawan Sharma
- Center for Translational Medicine, Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, Pennsylvania; and
| | - Alfredo Panebra
- Department of Medicine (Pulmonary Division), University of Maryland, Baltimore, Maryland
| | - Tonio Pera
- Center for Translational Medicine, Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, Pennsylvania; and
| | - Brian C Tiegs
- Center for Translational Medicine, Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, Pennsylvania; and
| | - Alena Hershfeld
- Department of Medicine (Pulmonary Division), University of Maryland, Baltimore, Maryland
| | - Lawrence C Kenyon
- Department of Pathology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Deepak A Deshpande
- Center for Translational Medicine, Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, Pennsylvania; and
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62
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Saglani S, Lloyd CM. Novel concepts in airway inflammation and remodelling in asthma. Eur Respir J 2015; 46:1796-804. [PMID: 26541520 DOI: 10.1183/13993003.01196-2014] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 08/25/2015] [Indexed: 02/03/2023]
Abstract
The hallmark pathological features of asthma include airway eosinophilic inflammation and structural changes (remodelling) which are associated with an irreversible loss in lung function that tracks from childhood to adulthood. In parallel with changes in function, pathological abnormalities occur early, during the pre-school years, are established by school age and subsequently remain (even though symptoms may remit for periods during adulthood). Given the equal importance of inflammation and remodelling in asthma pathogenesis, there is a significant disparity in studies undertaken to investigate the contribution of each. The majority focus on the role of inflammation, and although novel therapeutics such as those targeted against T-helper cell type 2 (Th2) mediators have arisen, it is apparent that targeting inflammation alone has not allowed disease modification. Therefore, unless airway remodelling is addressed for future therapeutic strategies, it is unlikely that we will progress towards a cure for asthma. Having acknowledged these limitations, the focus of this review is to highlight the gaps in our current knowledge about the mechanisms underlying airway remodelling, the relationships between remodelling, inflammation and function, remodelling and clinical phenotypes, and the importance of utilising innovative and realistic pre-clinical models to uncover effective, disease-modifying therapeutic strategies.
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Affiliation(s)
- Sejal Saglani
- Inflammation, Repair and Development Section, National Heart & Lung Institute, Imperial College London, London, UK Dept of Respiratory Paediatrics, Royal Brompton Hospital, London, UK
| | - Clare M Lloyd
- Inflammation, Repair and Development Section, National Heart & Lung Institute, Imperial College London, London, UK
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GLP-1 secretion is stimulated by 1,10-phenanthroline via colocalized T2R5 signal transduction in human enteroendocrine L cell. Biochem Biophys Res Commun 2015; 468:306-11. [PMID: 26505793 DOI: 10.1016/j.bbrc.2015.10.107] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2015] [Accepted: 10/20/2015] [Indexed: 12/25/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) hormone is known to regulate blood glucose by an insulinotropic effect and increases proliferation as and also prevents apoptosis of pancreatic β cells. We know that GLP-1 is secreted by nutrients such as fatty acids and sweet compounds but also bitter compounds via stimulation of G-protein coupled receptors (GPCRs) in the gut. Among these, bitter compounds are multiply-contained in phytochemicals or artificial materials and perceived as ligands of various bitter taste receptors. We hypothesized that GLP-1 hormone is secreted through stimulation of a single bitter taste receptor by 1,10-phenanthroline which is known agonist of taste receptor type 2 member 5 (T2R5). To prove this hypothesis, we used the representatively well-known 1,10-phenanthroline as ligand of single receptor and evaluated the existence of T2R5 by double-labeling immunofluorescence and then 1,10-phenanthroline is able to secrete GLP-1 hormone through stimulation of T2R5 in human enteroendocrine cells. Consequently, we verify that GLP-1 hormone is colocalized with T2R5 in the human duodenum and ileum tissue and is secreted by 1,10-phenanthroline via T2R5 signal transduction in differentiated human enteroendocrine L cells.
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Traitements inhalés : critères de choix des dispositifs, absorption systémique des médicaments par voie inhalée et récepteurs pulmonaires à l’amertume. Rev Mal Respir 2015; 32:791-9. [DOI: 10.1016/j.rmr.2014.06.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 06/12/2014] [Indexed: 11/18/2022]
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Abstract
PURPOSE OF REVIEW Although today's cornerstone therapies for asthma (inhaled bronchodilators and corticosteroids) target airway narrowing and lung inflammation, about half of treated asthmatic patients do not achieve good disease control. There is a clear need for new therapeutic approaches and novel drug targets. Recent research has unexpectedly revealed that certain taste receptors (particularly those involved in bitter taste transduction) are expressed in lung tissue. RECENT FINDINGS Bitter taste receptors are expressed in several cell types in the lungs (such as chemosensory cells, epithelial cells, smooth muscle cells, lymphocytes, and macrophages) and variously involved in ciliary beating, muscle relaxation, and/or inhibition of the production of inflammatory mediators. Here, we review recent research on the role of bitter taste receptors in experimental models of asthma and in asthmatics. SUMMARY The currently available data suggest that bitter taste receptor agonists have therapeutic potential in chronic obstructive airway diseases such as asthma.
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Role of the bitter taste receptor T2R38 in upper respiratory infection and chronic rhinosinusitis. Curr Opin Allergy Clin Immunol 2015; 15:14-20. [PMID: 25304231 DOI: 10.1097/aci.0000000000000120] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE OF REVIEW Taste receptor family 2 (T2R) bitter taste receptors were originally identified and named on the basis of their role in type 2 taste cells of the tongue, in which they serve to detect the presence of potentially harmful ingested chemicals. In 2009, researchers demonstrated that airway epithelial cells also express T2R receptors, but their role in airway physiology and human disease has only recently begun to be identified. RECENT FINDINGS Recent research has demonstrated that at least one airway T2R receptor, taste receptor family 2 isoform 38 protein (T2R38) is activated by secreted bacterial products. Activation of T2R38 in sinonasal epithelial cells stimulates nitric oxide production, increasing ciliary beating and directly killing bacteria. Clinical studies have also found correlations of TAS2R38 genotype with susceptibility to gram-negative upper respiratory infection and established T2R38 as an independent risk factor for chronic rhinosinusitis requiring sinus surgery. SUMMARY These recent studies identify a role for T2R38 in sinonasal innate immunity and chronic rhinosinusitis. Clinical implications include the potential development of T2R38-directed topical therapies, as well as using taste testing and/or genotyping to predict susceptibility to infection. Further studies are needed to more clearly determine how TAS2R38 genotype affects patient outcomes in chronic rhinosinusitis and other upper airway diseases.
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Devillier P, Naline E, Grassin-Delyle S. The pharmacology of bitter taste receptors and their role in human airways. Pharmacol Ther 2015; 155:11-21. [PMID: 26272040 DOI: 10.1016/j.pharmthera.2015.08.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The receptors involved in bitter taste perception (bitter taste receptors--T2Rs) constitute a family of G-protein-coupled receptors, of which around 29 subtypes have been identified in humans. T2R expression was initially thought to be confined to the oral cavity but has recently been described in a range of other tissues (such as the heart, gut, nasal cavity and lungs) and cell types (chemosensory, smooth muscle, endothelial, epithelial and inflammatory cells). Although it is still not clear whether endogenous T2R agonists exist, the T2R receptors recognize many natural and synthetic compounds, such as the acyl-homoserine lactones produced by bacteria, caffeine, chloroquine, and erythromycin. In the upper airways, T2Rs are involved in neurogenic inflammation and bacterial clearance. Their known effects in the lungs are exerted at three different levels. Firstly, T2R agonists increase the beating frequency of cilia on epithelial cells. Secondly, the T2Rs induce bronchial smooth muscle cells to relax. Thirdly, the T2R receptors expressed on immune cells (such as macrophages and mast cells) modulate production of pro-inflammatory mediators. Furthermore, T2R agonists are effective in inhibiting lung inflammation or smooth muscle contraction in ex vivo and asthma animal models, and are known to be involved in bacterial killing in the nasal cavity and enhancing lung function in humans. This review focuses on the pharmacology and physiological functions of T2R receptors in the upper and lower airways. It presents recently acquired knowledge suggesting that T2Rs may become valuable drug targets in the treatment of diseases such as asthma and chronic rhinosinusitis.
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Affiliation(s)
- Philippe Devillier
- Laboratoire de Pharmacologie, UPRES EA220, Hôpital Foch, 11 rue Guillaume Lenoir, 92150 Suresnes, France; Université Versailles Saint Quentin en Yvelines, UFR Sciences de la Santé, 2 avenue de la source de la Bièvre, 78180 Montigny-le-Bretonneux, France
| | - Emmanuel Naline
- Laboratoire de Pharmacologie, UPRES EA220, Hôpital Foch, 11 rue Guillaume Lenoir, 92150 Suresnes, France; Université Versailles Saint Quentin en Yvelines, UFR Sciences de la Santé, 2 avenue de la source de la Bièvre, 78180 Montigny-le-Bretonneux, France
| | - Stanislas Grassin-Delyle
- Laboratoire de Pharmacologie, UPRES EA220, Hôpital Foch, 11 rue Guillaume Lenoir, 92150 Suresnes, France; Université Versailles Saint Quentin en Yvelines, UFR Sciences de la Santé, 2 avenue de la source de la Bièvre, 78180 Montigny-le-Bretonneux, France.
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Camoretti-Mercado B, Pauer SH, Yong HM, Smith DC, Deshpande DA, An SS, Liggett SB. Pleiotropic Effects of Bitter Taste Receptors on [Ca2+]i Mobilization, Hyperpolarization, and Relaxation of Human Airway Smooth Muscle Cells. PLoS One 2015; 10:e0131582. [PMID: 26121686 PMCID: PMC4485472 DOI: 10.1371/journal.pone.0131582] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 06/03/2015] [Indexed: 01/25/2023] Open
Abstract
Asthma is characterized by airway inflammation and airflow obstruction from human airway smooth muscle (HASM) constriction due to increased local bronchoconstrictive substances. We have recently found bitter taste receptors (TAS2Rs) on HASM, which increase [Ca2+]i and relax the muscle. We report here that some, but not all, TAS2R agonists decrease [Ca2+]i and relax HASM contracted by G-protein coupled receptors (GPCRs) that stimulate [Ca2+]i. This suggests both a second pathway by which TAS2Rs relax, and, a heterogeneity of the response phenotype. We utilized eight TAS2R agonists and five procontractile GPCR agonists in cultured HASM cells. We find that heterogeneity in the inhibitory response hinges on which procontractile GPCR is activated. For example, chloroquine inhibits [Ca2+]i increases from histamine, but failed to inhibit [Ca2+]i increases from endothelin-1. Conversely, aristolochic acid inhibited [Ca2+]i increases from endothelin-1 but not histamine. Other dichotomous responses were found when [Ca2+]i was stimulated by bradykinin, angiotensin, and acetylcholine. There was no association between [Ca2+]i inhibition and TAS2R subtype, nor whether [Ca2+]i was increased by Gq- or Gi-coupled GPCRs. Selected studies revealed a correlation between [Ca2+]i inhibition and HASM cell-membrane hyperpolarization. To demonstrate physiologic correlates, ferromagnetic beads were attached to HASM cells and cell stiffness measured by magnetic twisting cytometry. Consistent with the [Ca2+]i inhibition results, chloroquine abolished the cell stiffening response (contraction) evoked by histamine but not by endothelin-1, while aristolochic acid inhibited cell stiffening from endothelin-1, but not from histamine. In studies using intact human bronchi, these same differential responses were found. Those TAS2R agonists that decreased [Ca2+]i, promoted hyperpolarization, and decreased HASM stiffness, caused relaxation of human airways. Thus TAS2Rs relax HASM in two ways: a low-efficiency de novo [Ca2+]i stimulation, and, a high-efficiency inhibition of GPCR-stimulated [Ca2+]i. Furthermore, there is an interaction between TAS2Rs and some GPCRs that facilitates this [Ca2+]i inhibition limb.
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Affiliation(s)
- Blanca Camoretti-Mercado
- Department of Medicine and the Center for Personalized Medicine and Genomics, University of South Florida Morsani College of Medicine, Tampa, FL, United States of America
| | - Susan H. Pauer
- Department of Medicine and the Center for Personalized Medicine and Genomics, University of South Florida Morsani College of Medicine, Tampa, FL, United States of America
| | - Hwan Mee Yong
- Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Dan’elle C. Smith
- Department of Medicine and the Center for Personalized Medicine and Genomics, University of South Florida Morsani College of Medicine, Tampa, FL, United States of America
| | - Deepak A. Deshpande
- Department of Medicine and Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Steven S. An
- Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Stephen B. Liggett
- Department of Medicine and the Center for Personalized Medicine and Genomics, University of South Florida Morsani College of Medicine, Tampa, FL, United States of America
- Department of Molecular Pharmacology and Physiology, University of South Florida Morsani College of Medicine, Tampa, FL, United States of America
- * E-mail:
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Lee RJ, Cohen NA. Taste receptors in innate immunity. Cell Mol Life Sci 2015; 72:217-36. [PMID: 25323130 PMCID: PMC4286424 DOI: 10.1007/s00018-014-1736-7] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/11/2014] [Accepted: 09/16/2014] [Indexed: 02/07/2023]
Abstract
Taste receptors were first identified on the tongue, where they initiate a signaling pathway that communicates information to the brain about the nutrient content or potential toxicity of ingested foods. However, recent research has shown that taste receptors are also expressed in a myriad of other tissues, from the airway and gastrointestinal epithelia to the pancreas and brain. The functions of many of these extraoral taste receptors remain unknown, but emerging evidence suggests that bitter and sweet taste receptors in the airway are important sentinels of innate immunity. This review discusses taste receptor signaling, focusing on the G-protein-coupled receptors that detect bitter, sweet, and savory tastes, followed by an overview of extraoral taste receptors and in-depth discussion of studies demonstrating the roles of taste receptors in airway innate immunity. Future research on extraoral taste receptors has significant potential for identification of novel immune mechanisms and insights into host-pathogen interactions.
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Affiliation(s)
- Robert J. Lee
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, Ravdin Building, 5th floor, Philadelphia, PA 19104 USA
| | - Noam A. Cohen
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, Ravdin Building, 5th floor, Philadelphia, PA 19104 USA
- Philadelphia Veterans Affairs Medical Center Surgical Services, 3900 Woodland Ave, Philadelphia, PA 19104 USA
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Bitter and sweet taste receptors in the respiratory epithelium in health and disease. J Mol Med (Berl) 2014; 92:1235-44. [PMID: 25391251 DOI: 10.1007/s00109-014-1222-6] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 11/01/2014] [Accepted: 11/04/2014] [Indexed: 11/27/2022]
Abstract
Taste receptors on the tongue communicate information to the brain about the nutrient content or potential toxicity of ingested foods. However, recent research has now shown that taste receptors are also expressed far beyond the tongue, from the airway and gastrointestinal epithelia to the pancreas and brain. The functions of many of these so-called extraoral taste receptors remain unknown, but emerging basic science and clinical evidence suggests that bitter and sweet taste receptors in the airway are important in sensing bacteria and regulating innate immunity. This review focuses on the role of bitter and sweet taste receptors in human airway innate immunity and the potential clinical relevance to airway infections. The T2R38 bitter taste receptor in sinonasal cilia detects bitter bacterial quorum-sensing molecules and activates nitric oxide-dependent innate immune responses. Polymorphisms that underlie T2R38 functionality also appear to be involved in susceptibility to upper respiratory infection and chronic rhinosinusitis (CRS). Bitter and sweet receptors in specialized sinonasal solitary chemosensory cells control antimicrobial peptide secretion, which may have important implications for airway infections in CRS patients as well as patients with diabetes mellitus. Future research on taste receptors in the airway has tremendous potential to identify immune mechanisms involved in host-pathogen interactions and thus reveal novel therapeutic targets.
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Faisy C, Grassin-Delyle S, Blouquit-Laye S, Brollo M, Naline E, Chapelier A, Devillier P. Wnt/β-catenin signaling modulates human airway sensitization induced by β2-adrenoceptor stimulation. PLoS One 2014; 9:e111350. [PMID: 25360795 PMCID: PMC4216012 DOI: 10.1371/journal.pone.0111350] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 09/23/2014] [Indexed: 11/23/2022] Open
Abstract
Background Regular use of β2-agonists may enhance non-specific airway responsiveness. The wingless/integrated (Wnt) signaling pathways are responsible for several cellular processes, including airway inflammation and remodeling while cAMP–PKA cascade can activate the Wnt signaling. We aimed to investigate whether the Wnt signaling pathways are involved in the bronchial hyperresponsiveness induced by prolonged exposure to β2-adrenoceptor agonists in human isolated airways. Methods Bronchi were surgically removed from 44 thoracic surgery patients. After preparation, bronchial rings and primary cultures of bronchial epithelial cells were incubated with fenoterol (0.1 µM, 15 hours, 37°C), a β2-agonist with high intrinsic efficacy. The effects of inhibitors/blockers of Wnt signaling on the fenoterol-induced airway sensitization were examined and the impact of fenoterol exposure on the mRNA expression of genes interacting with Wnt signaling or cAMP–PKA cascade was assessed in complete bronchi and in cultured epithelial cells. Results Compared to paired controls, fenoterol-sensitization was abolished by inhibition/blockage of the Wnt/β-catenin signaling, especially the cell-surface LRP5/6 co-receptors or Fzd receptors (1 µM SFRP1 or 1 µM DKK1) and the nuclear recruitment of TCF/LEF transcriptions factors (0.3 µM FH535). Wnt proteins secretion did not seem to be involved in the fenoterol-induced sensitization since the mRNA expression of Wnt remained low after fenoterol exposure and the inactivator of Wnt secretion (1 µM IWP2) had no effect on the fenoterol-sensitization. Fenoterol exposure did not change the mRNA expression of genes regulating Wnt signaling or cAMP–PKA cascade. Conclusions Collectively, our pharmacological investigations indicate that fenoterol-sensitization is modulated by the inhibition/blockage of canonical Wnt/β-catenin pathway, suggesting a phenomenon of biased agonism in connection with the β2-adrenoceptor stimulation. Future experiments based on the results of the present study will be needed to determine the impact of prolonged fenoterol exposure on the extra- and intracellular Wnt signaling pathways at the protein expression level.
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Affiliation(s)
- Christophe Faisy
- Unité Propre de Recherche de l'Enseignement Supérieur, Equipe d'Accueil 220, Université Versailles Saint–Quentin, Hôpital Foch, Suresnes, France
- Medical Intensive Care Unit, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France
- * E-mail:
| | - Stanislas Grassin-Delyle
- Unité Propre de Recherche de l'Enseignement Supérieur, Equipe d'Accueil 220, Université Versailles Saint–Quentin, Hôpital Foch, Suresnes, France
| | - Sabine Blouquit-Laye
- Unité Propre de Recherche de l'Enseignement Supérieur, Equipe d'Accueil 220, Université Versailles Saint–Quentin, Hôpital Foch, Suresnes, France
| | - Marion Brollo
- Unité Propre de Recherche de l'Enseignement Supérieur, Equipe d'Accueil 220, Université Versailles Saint–Quentin, Hôpital Foch, Suresnes, France
| | - Emmanuel Naline
- Unité Propre de Recherche de l'Enseignement Supérieur, Equipe d'Accueil 220, Université Versailles Saint–Quentin, Hôpital Foch, Suresnes, France
| | - Alain Chapelier
- Department of Thoracic Surgery, Hôpital Foch, Suresnes, France
| | - Philippe Devillier
- Unité Propre de Recherche de l'Enseignement Supérieur, Equipe d'Accueil 220, Université Versailles Saint–Quentin, Hôpital Foch, Suresnes, France
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Cholinergic epithelial cell with chemosensory traits in murine thymic medulla. Cell Tissue Res 2014; 358:737-48. [PMID: 25300645 PMCID: PMC4233111 DOI: 10.1007/s00441-014-2002-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 09/04/2014] [Indexed: 12/17/2022]
Abstract
Specialized epithelial cells with a tuft of apical microvilli (“brush cells”) sense luminal content and initiate protective reflexes in response to potentially harmful substances. They utilize the canonical taste transduction cascade to detect “bitter” substances such as bacterial quorum-sensing molecules. In the respiratory tract, most of these cells are cholinergic and are approached by cholinoceptive sensory nerve fibers. Utilizing two different reporter mouse strains for the expression of choline acetyltransferase (ChAT), we observed intense labeling of a subset of thymic medullary cells. ChAT expression was confirmed by in situ hybridization. These cells showed expression of villin, a brush cell marker protein, and ultrastructurally exhibited lateral microvilli. They did not express neuroendocrine (chromogranin A, PGP9.5) or thymocyte (CD3) markers but rather thymic epithelial (CK8, CK18) markers and were immunoreactive for components of the taste transduction cascade such as Gα-gustducin, transient receptor potential melastatin-like subtype 5 channel (TRPM5), and phospholipase Cβ2. Reverse transcription and polymerase chain reaction confirmed the expression of Gα-gustducin, TRPM5, and phospholipase Cβ2. Thymic “cholinergic chemosensory cells” were often in direct contact with medullary epithelial cells expressing the nicotinic acetylcholine receptor subunit α3. These cells have recently been identified as terminally differentiated epithelial cells (Hassall’s corpuscle-like structures in mice). Contacts with nerve fibers (identified by PGP9.5 and CGRP antibodies), however, were not observed. Our data identify, in the thymus, a previously unrecognized presumptive chemosensitive cell that probably utilizes acetylcholine for paracrine signaling. This cell might participate in intrathymic infection-sensing mechanisms.
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Manson ML, Säfholm J, Al-Ameri M, Bergman P, Orre AC, Swärd K, James A, Dahlén SE, Adner M. Bitter taste receptor agonists mediate relaxation of human and rodent vascular smooth muscle. Eur J Pharmacol 2014; 740:302-11. [DOI: 10.1016/j.ejphar.2014.07.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 07/03/2014] [Accepted: 07/04/2014] [Indexed: 02/04/2023]
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Zhang T, Luo XJ, Sai WB, Yu MF, Li WE, Ma YF, Chen W, Zhai K, Qin G, Guo D, Zheng YM, Wang YX, Shen JH, Ji G, Liu QH. Non-selective cation channels mediate chloroquine-induced relaxation in precontracted mouse airway smooth muscle. PLoS One 2014; 9:e101578. [PMID: 24992312 PMCID: PMC4081631 DOI: 10.1371/journal.pone.0101578] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 06/06/2014] [Indexed: 02/01/2023] Open
Abstract
Bitter tastants can induce relaxation in precontracted airway smooth muscle by activating big-conductance potassium channels (BKs) or by inactivating voltage-dependent L-type Ca2+ channels (VDLCCs). In this study, a new pathway for bitter tastant-induced relaxation was defined and investigated. We found nifedipine-insensitive and bitter tastant chloroquine-sensitive relaxation in epithelium-denuded mouse tracheal rings (TRs) precontracted with acetylcholine (ACH). In the presence of nifedipine (10 µM), ACH induced cytosolic Ca2+ elevation and cell shortening in single airway smooth muscle cells (ASMCs), and these changes were inhibited by chloroquine. In TRs, ACH triggered a transient contraction under Ca2+-free conditions, and, following a restoration of Ca2+, a strong contraction occurred, which was inhibited by chloroquine. Moreover, the ACH-activated whole-cell and single channel currents of non-selective cation channels (NSCCs) were blocked by chloroquine. Pyrazole 3 (Pyr3), an inhibitor of transient receptor potential C3 (TRPC3) channels, partially inhibited ACH-induced contraction, intracellular Ca2+ elevation, and NSCC currents. These results demonstrate that NSCCs play a role in bitter tastant-induced relaxation in precontracted airway smooth muscle.
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Affiliation(s)
- Ting Zhang
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Xiao-Jing Luo
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Wen-Bo Sai
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Meng-Fei Yu
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Wen-Er Li
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Yun-Fei Ma
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Weiwei Chen
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Kui Zhai
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Gangjian Qin
- Department of Medicine-Cardiology, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Donglin Guo
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
- Lankenau Institute for Medical Research & Main Line Health Heart Center, Wynnewood, Pennsylvania, United States of America
| | - Yun-Min Zheng
- Center for Cardiovascular Sciences, Albany Medical College, Albany, New York, United States of America
| | - Yong-Xiao Wang
- Center for Cardiovascular Sciences, Albany Medical College, Albany, New York, United States of America
| | - Jin-Hua Shen
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Guangju Ji
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- * E-mail: (QHL); (GJ)
| | - Qing-Hua Liu
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan, China
- * E-mail: (QHL); (GJ)
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Grassin-Delyle S, Abrial C, Brollo M, Naline E, Devillier P. [Taste receptors in the lungs: interesting or anecdotal?]. REVUE DE PNEUMOLOGIE CLINIQUE 2014; 70:148-155. [PMID: 24646786 DOI: 10.1016/j.pneumo.2013.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 11/08/2013] [Accepted: 11/12/2013] [Indexed: 06/03/2023]
Abstract
The receptors responsible for taste perception distinguish the four basic tastes : salty, sweet, bitter and umami. Among them, the bitter taste receptors (TAS2R) are G protein coupled receptors, including 25 subtypes identified in humans to date. Although the existence of endogenous agonists remains uncertain, the TAS2R receptors have the ability to recognize natural or synthetic molecules, as various molecules produced by bacteria, or caffeine, chloroquine, or erythromycin. The expression of these receptors, initially thought to be confined to the oral cavity, has recently been described in extra-oral tissues such as the gastrointestinal tract and the lungs. The effects in the lung tissue are essentially at three levels : TAS2R receptors expressed on the cilia of epithelial cells increase the cilia vibration frequency; the stimulation of TAS2R receptors expressed in bronchial smooth muscle cells leads to bronchial relaxation; while TAS2R receptors expressed on immune cells in the lung tissue, including macrophages, are involved in the modulation of the production of pro-inflammatory cytokines. In conclusion, in view of these complementary mechanisms, TAS2R receptors may become a pharmacological target of interest for the treatment of obstructive lung diseases.
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Affiliation(s)
- S Grassin-Delyle
- Laboratoire de pharmacologie respiratoire UPRES EA220, hôpital Foch, 11, rue Guillaume-Lenoir, 92150 Suresnes, France.
| | - C Abrial
- Laboratoire de pharmacologie respiratoire UPRES EA220, hôpital Foch, 11, rue Guillaume-Lenoir, 92150 Suresnes, France
| | - M Brollo
- Laboratoire de pharmacologie respiratoire UPRES EA220, hôpital Foch, 11, rue Guillaume-Lenoir, 92150 Suresnes, France
| | - E Naline
- Laboratoire de pharmacologie respiratoire UPRES EA220, hôpital Foch, 11, rue Guillaume-Lenoir, 92150 Suresnes, France; Université Versailles Saint-Quentin, UFR sciences de la santé Simone-Veil, 2, avenue de la Source-de-la-Bièvre, 78180 Montigny-Le-Bretonneux, France
| | - P Devillier
- Laboratoire de pharmacologie respiratoire UPRES EA220, hôpital Foch, 11, rue Guillaume-Lenoir, 92150 Suresnes, France; Université Versailles Saint-Quentin, UFR sciences de la santé Simone-Veil, 2, avenue de la Source-de-la-Bièvre, 78180 Montigny-Le-Bretonneux, France
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Tucker RM, Mattes RD, Running CA. Mechanisms and effects of "fat taste" in humans. Biofactors 2014; 40:313-26. [PMID: 24591077 DOI: 10.1002/biof.1162] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 02/18/2014] [Indexed: 12/11/2022]
Abstract
Evidence supporting a "taste" cue from fat in the oral cavity continues to accrue. The proposed stimuli for fat taste, non-esterified fatty acids (NEFA), are released from food through hydrolytic rancidity and lipase activity derived from foods or saliva. NEFA must then be released from the food matrix, negotiate the aqueous environment to reach taste cell surfaces, and interact with receptors such as CD36 and GPR120 or diffuse across cell membranes to initiate a taste signal. Knowledge of these processes in non-gustatory tissues should inform understanding of taste responses to NEFA. Additionally, downstream effects of oral triglyceride exposure have been observed in numerous studies. Data specific to effects of NEFA versus triglyceride are scarce, but modified sham feeding trials with triglyceride document cephalic phase responses including elevations in serum lipids and insulin as well as potential, but debated, effects on gut peptides, appetite, and thermogenesis. In this review, we highlight the mechanisms by which NEFA migrate to and interact with taste cells, and then we examine physiological responses to oral fat exposure.
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Affiliation(s)
- Robin M Tucker
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
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