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Wils T, Backaert W, Jacobs I, Ruysseveldt E, Cremer J, Dilissen E, Bullens DM, Talavera K, Steelant B, Van Gerven L, Martens K, Hellings PW. Rare presence and function of neuroendocrine cells in the nasal mucosa. Front Immunol 2024; 15:1394539. [PMID: 39176088 PMCID: PMC11339793 DOI: 10.3389/fimmu.2024.1394539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Accepted: 07/24/2024] [Indexed: 08/24/2024] Open
Abstract
There is growing evidence that neurogenic inflammation contributes to the pathophysiology of upper airway diseases, with nasal hyperreactivity (NHR) being a key symptom. The rare neuroendocrine cells (NECs) in the epithelium have been linked to the pathophysiology of bronchial and intestinal hyperreactivity, however their presence in the nasal mucosa and their potential role in NHR remains unclear. Therefore, we studied the presence of NECs in the nasal epithelium of controls, allergic rhinitis patients and chronic rhinosinusitis with nasal polyps patients, and their link to NHR. The expression of typical NECs markers, CHGA, ASCL1 and CGRP, were evaluated on gene and protein level in human samples using real-time quantitative PCR (RT-qPCR), western blot, immunohistochemistry fluorescence staining, RNA scope assay, flow cytometry and single cell RNA-sequencing. Furthermore, the change in peak nasal inspiratory flow after cold dry air provocation and visual analogue scale scores were used to evaluate NHR or disease severity, respectively. Limited gene expression of the NECs markers CHGA and ASCL1 was measured in patients with upper airway diseases and controls. Gene expression of these markers did not correlate with NHR severity nor disease severity. In vitro, CHGA and ASCL1 expression was also evaluated in primary nasal epithelial cell cultures from patients with upper airway disease and controls using RT-qPCR and western blot. Both on gene and protein level only limited CHGA and ASCL1 expression was found. Additionally, NECs were studied in nasal biopsies of patients with upper airway diseases and controls using immunohistochemistry fluorescence staining, RNA scope and flow cytometry. Unlike in ileum samples, CHGA could not be detected in nasal biopsies of patients with upper airway diseases and control subjects. Lastly, single cell RNA-sequencing of upper airway tissue could not identify a NEC cluster. In summary, in contrast to the bronchi and gut, there is only limited evidence for the presence of NECs in the nasal mucosa, and without correlation with NHR, thereby questioning the relevance of NECs in upper airway pathology.
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Affiliation(s)
- Tine Wils
- KU Leuven Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
| | - Wout Backaert
- KU Leuven Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
- Clinical Department of Otorhinolaryngology, Head and Neck Surgery, University Hospitals Leuven, Leuven, Belgium
| | - Inge Jacobs
- KU Leuven Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
- KU Leuven Department of Chronic Diseases and Metabolism, Translational Research Center for Gastrointestinal Diseases, KU Leuven, Leuven, Belgium
| | - Emma Ruysseveldt
- KU Leuven Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
| | - Jonathan Cremer
- KU Leuven Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
| | - Ellen Dilissen
- KU Leuven Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
| | - Dominique M. Bullens
- KU Leuven Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
- Department of Pediatrics, University Hospitals Leuven, Leuven, Belgium
| | - Karel Talavera
- KU Leuven Department of Cellular and Molecular Medicine, Laboratory of Ion Channel Research Division of Physiology, KU Leuven, Leuven, Belgium
| | - Brecht Steelant
- KU Leuven Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
| | - Laura Van Gerven
- KU Leuven Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
- Clinical Department of Otorhinolaryngology, Head and Neck Surgery, University Hospitals Leuven, Leuven, Belgium
- KU Leuven Department of Neurosciences, Experimental Otorhinolaryngology Rhinology Research, KU Leuven, Leuven, Belgium
| | - Katleen Martens
- KU Leuven Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
- University of Antwerp (UAntwerp) Department of Bioscience Engineering, Lab of Applied Microbiology and Biotechnology, University of Antwerp (UAntwerp), Antwerp, Belgium
| | - Peter W. Hellings
- KU Leuven Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
- Clinical Department of Otorhinolaryngology, Head and Neck Surgery, University Hospitals Leuven, Leuven, Belgium
- University of Ghent (UGhent) Department of Head and Skin, Upper Airways Research Laboratory, University of Ghent (UGhent), Ghent, Belgium
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Xu J, Yu H, Sun X. Less Is More: Rare Pulmonary Neuroendocrine Cells Function as Critical Sensors in Lung. Dev Cell 2020; 55:123-132. [PMID: 33108755 DOI: 10.1016/j.devcel.2020.09.024] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 09/04/2020] [Accepted: 09/23/2020] [Indexed: 12/14/2022]
Abstract
Pulmonary neuroendocrine cells (PNECs) are rare airway epithelial cells that also uniquely harbor neuronal and endocrine characteristics. In vitro data indicate that these cells respond to chemical or mechanical stimuli by releasing neuropeptides and neurotransmitters, implicating them as airway sensors. Emerging in vivo data corroborate this role and demonstrate that PNECs are important for lung response to signals, such as allergens. With close proximity to steady-state immune cells and innervating nerves, PNECs, as prototype tissue-resident neuroendocrine cells, are at the center of a neuro-immune module that enables the fundamental ability of an organ to sense and respond to the environment.
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Affiliation(s)
- Jinhao Xu
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA; Department of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Haoze Yu
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Xin Sun
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA; Department of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
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Garg A, Sui P, Verheyden JM, Young LR, Sun X. Consider the lung as a sensory organ: A tip from pulmonary neuroendocrine cells. Curr Top Dev Biol 2019; 132:67-89. [PMID: 30797518 DOI: 10.1016/bs.ctdb.2018.12.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
While the lung is commonly known for its gas exchange function, it is exposed to signals in the inhaled air and responds to them by collaborating with other systems including immune cells and the neural circuit. This important aspect of lung physiology led us to consider the lung as a sensory organ. Among different cell types within the lung that mediate this role, several recent studies have renewed attention on pulmonary neuroendocrine cells (PNECs). PNECs are a rare, innervated airway epithelial cell type that accounts for <1% of the lung epithelium population. They are enriched at airway branch points. Classical in vitro studies have shown that PNECs can respond to an array of aerosol stimuli such as hypoxia, hypercapnia and nicotine. Recent in vivo evidence suggests an essential role of PNECs at neuroimmunomodulatory sites of action, releasing neuropeptides, neurotransmitters and facilitating asthmatic responses to allergen. In addition, evidence supports that PNECs can function both as progenitor cells and progenitor niches following airway epithelial injury. Increases in PNECs have been documented in a large array of chronic lung diseases. They are also the cells-of-origin for small cell lung cancer. A better understanding of the specificity of their responses to distinct insults, their impact on normal lung function and their roles in the pathogenesis of pulmonary ailments will be the next challenge toward designing therapeutics targeting the neuroendocrine system in lung.
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Affiliation(s)
- Ankur Garg
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States
| | - Pengfei Sui
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States
| | - Jamie M Verheyden
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States
| | - Lisa R Young
- Division of Pulmonary Medicine, Center for Childhood Lung Research, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Xin Sun
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States; Department of Biological Sciences, University of California, San Diego, La Jolla, CA, United States.
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Mazzone SB, Undem BJ. Vagal Afferent Innervation of the Airways in Health and Disease. Physiol Rev 2017; 96:975-1024. [PMID: 27279650 DOI: 10.1152/physrev.00039.2015] [Citation(s) in RCA: 326] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Vagal sensory neurons constitute the major afferent supply to the airways and lungs. Subsets of afferents are defined by their embryological origin, molecular profile, neurochemistry, functionality, and anatomical organization, and collectively these nerves are essential for the regulation of respiratory physiology and pulmonary defense through local responses and centrally mediated neural pathways. Mechanical and chemical activation of airway afferents depends on a myriad of ionic and receptor-mediated signaling, much of which has yet to be fully explored. Alterations in the sensitivity and neurochemical phenotype of vagal afferent nerves and/or the neural pathways that they innervate occur in a wide variety of pulmonary diseases, and as such, understanding the mechanisms of vagal sensory function and dysfunction may reveal novel therapeutic targets. In this comprehensive review we discuss historical and state-of-the-art concepts in airway sensory neurobiology and explore mechanisms underlying how vagal sensory pathways become dysfunctional in pathological conditions.
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Affiliation(s)
- Stuart B Mazzone
- School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, Australia; and Department of Medicine, Johns Hopkins University Medical School, Asthma & Allergy Center, Baltimore, Maryland
| | - Bradley J Undem
- School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, Australia; and Department of Medicine, Johns Hopkins University Medical School, Asthma & Allergy Center, Baltimore, Maryland
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Pan J, Yeger H, Cutz E. Innervation of Pulmonary Neuroendocrine Cells and Neuroepithelial Bodies in Developing Rabbit Lung. J Histochem Cytochem 2016; 52:379-89. [PMID: 14966205 DOI: 10.1177/002215540405200309] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We investigated the development of innervation of the pulmonary neuroendocrine cell (PNEC) system composed of single cells and organoid cell clusters, neuroepithelial bodies (NEB) in rabbit fetal and neonatal lungs. To visualize the nerve fibers and their contacts with PNECs/NEBs, we used confocal microscopy and multilabel immunohistochemistry (IHC) with pan-neural marker, synaptic vesicle protein 2 (SV2), and serotonin (5-HT) as markers for PNECs/NEBs, and smooth muscle actin or cytokeratin to identify airway landmarks. The numbers and distribution of PNEC/NEB at different stages of lung development (E16, 18, 21, 26, and P2) and the density of innervation were quantified. First PNECs immunoreactive for 5-HT were identified in primitive airway epithelium at E18 as single cells or as small cell clusters with or without early nerve contacts. At E21 a significant increase in the number of PNECs with formation of early innervated NEB corpuscules was observed. The overall numbers of PNECs/NEBs and the density of mucosal, submucosal, and intercorpuscular innervation increased with progressing gestation and peaked postnataly (P2). At term, the majority of NEBs and single PNECs within airway mucosa possessed neural contacts. Such an extensive and complex innervation of the PNEC system indicates a multifunctional role in developing lung and during neonatal adaptation.
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Affiliation(s)
- Jie Pan
- Division of Pathology, Department of Pediatric Laboratory Medicine, The Research Institute, The Hospital for Sick Children, and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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Drozdowska J, Cousens C, Finlayson J, Collie D, Dagleish M. Structural Development, Cellular Differentiation and Proliferation of the Respiratory Epithelium in the Bovine Fetal Lung. J Comp Pathol 2016; 154:42-56. [DOI: 10.1016/j.jcpa.2015.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/28/2015] [Accepted: 11/06/2015] [Indexed: 11/26/2022]
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Martineau HM, Dagleish MP, Cousens C, Underwood C, Forbes V, Palmarini M, Griffiths DJ. Cellular differentiation and proliferation in the ovine lung during gestation and early postnatal development. J Comp Pathol 2013; 149:255-67. [PMID: 23356932 DOI: 10.1016/j.jcpa.2012.11.239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 10/16/2012] [Accepted: 11/23/2012] [Indexed: 11/26/2022]
Abstract
This study investigates epithelial cell differentiation and proliferation in specific anatomical regions of the ovine lung during prenatal and postnatal development. Immunohistochemistry was used to identify ciliated epithelial cells, Clara cells, neuroepithelial bodies and type II pneumocytes in the lungs of preterm (67, 127 and 140 days of gestation), full-term (147 days) and postnatal (9, 16 and 91 days old) lambs. Differentiation of ciliated epithelial cells was seen at 67 days of gestation and at term for Clara cells. Neuroepithelial bodies were first detected at 127 days of gestation. From 16 to 91 days of age there was a significant (P <0.05) increase in beta-tubulin (present in ciliated epithelial cells) and Clara cell protein (present in Clara cells) in multiple regions of the lung. Detection of Ki67, a marker of proliferation, in preterm lambs showed a reduction in proliferation index in multiple anatomical regions of the lung between 70 days of gestation and term. Cell proliferation increased following parturition, and then decreased between 16 and 91 days of age, with the largest reduction occurring in the alveolar compartment. Knowledge of which cells are present at specific times of lung development provides valuable information on the anatomy of the ovine lung, improving its use as a model for ovine and human neonatal disease. In addition, the antibodies used here will be valuable for future studies requiring the identification and quantification of respiratory epithelial cell phenotypes in the sheep lung.
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Affiliation(s)
- H M Martineau
- Moredun Research Institute, Pentlands Science Park, Penicuik EH26 0PZ, UK
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8
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Cutz E, Pan J, Yeger H, Domnik NJ, Fisher JT. Recent advances and contraversies on the role of pulmonary neuroepithelial bodies as airway sensors. Semin Cell Dev Biol 2012; 24:40-50. [PMID: 23022441 DOI: 10.1016/j.semcdb.2012.09.003] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 09/14/2012] [Indexed: 11/15/2022]
Abstract
Pulmonary neuroepithelial bodies are polymodal sensors widely distributed within the airway mucosa of mammals and other species. Neuroepithelial body cells store and most likely release serotonin and peptides as transmitters. Neuroepithelial bodies have a complex innervation that includes vagal sensory afferent fibers and dorsal root ganglion fibers. Neuroepithelial body cells respond to a number of intraluminal airway stimuli, including hypoxia, hypercarbia, and mechanical stretch. This article reviews recent findings in the cellular and molecular biology of neuroepithelial body cells and their potential role as airway sensors involved in the control of respiration, particularly during the perinatal period. Alternate hypotheses and areas of controversy regarding potential function as mechanosensory receptors involved in pulmonary reflexes are discussed.
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Affiliation(s)
- Ernest Cutz
- Division of Pathology, Department of Paediatric Laboratory Medicine, The Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.
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9
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Immunohistochemical characterization of nodose cough receptor neurons projecting to the trachea of guinea pigs. COUGH 2008; 4:9. [PMID: 18928572 PMCID: PMC2586627 DOI: 10.1186/1745-9974-4-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Accepted: 10/19/2008] [Indexed: 02/06/2023]
Abstract
Background Cough in guinea pigs is mediated in part by capsaicin-insensitive low threshold mechanoreceptors (cough receptors). Functional studies suggest that cough receptors represent a homogeneous population of nodose ganglia-derived sensory neurons. In the present study we set out to characterize the neurochemical profile of cough receptor neurons in the nodose ganglia. Methods Nodose neurons projecting to the guinea pig trachea were retrogradely labeled with fluorogold and processed immunohistochemically for the expression of a variety of transporters (Na+/K+/2C1- co-transporter (NKCC1), α1 and α3 Na+/K+ ATPase, vesicular glutamate transporters (vGlut)1 and vGlut2), neurotransmitters (substance P, calcitonin gene-related peptide (CGRP), somatostatin, neuronal nitric oxide synthase (nNOS)) and cytosolic proteins (neurofilament, calretinin, calbindin, parvalbumin). Results Fluorogold labeled ~3 per cent of neurons in the nodose ganglia with an average somal perimeter of 137 ± 6.2 μm (range 90–200 μm). All traced neurons (and seemingly all nodose neurons) were immunoreactive for NKCC1. Many (> 90 per cent) were also immunoreactive for vGlut2 and neurofilament and between 50 and 85 per cent expressed α1 ATPase, α3 ATPase or vGlut1. Cough receptor neurons that did not express the above markers could not be differentiated based on somal size, with the exception of neurofilament negative neurons which were significantly smaller (P < 0.05). Less than 10 per cent of fluorogold labeled neurons expressed substance P or CGRP (and these had somal perimeters less than 110 μm) and none expressed somatostatin, calretinin, calbindin or parvalbumin. Two distinct patterns of nNOS labeling was observed in the general population of nodose neurons: most neurons contained cytosolic clusters of moderately intense immunoreactivity whereas less than 10 per cent of neurons displayed uniform intensely fluorescent somal labeling. Less than 3 per cent of the retrogradely traced neurons were intensely fluorescent for nNOS (most showed clusters of nNOS immunoreactivity) and nNOS immunoreactivity was not expressed by cough receptor nerve terminals in the tracheal wall. Conclusion These data provide further insights into the neurochemistry of nodose cough receptors and suggest that despite their high degree of functional homogeneity, nodose cough receptors subtypes may eventually be distinguished based on neurochemical profile.
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Abstract
The guinea pig has been the most commonly used small animal species in preclinical studies related to asthma and COPD. The primary advantages of the guinea pig are the similar potencies and efficacies of agonists and antagonists in human and guinea pig airways and the many similarities in physiological processes, especially airway autonomic control and the response to allergen. The primary disadvantages to using guinea pigs are the lack of transgenic methods, limited numbers of guinea pig strains for comparative studies and a prominent axon reflex that is unlikely to be present in human airways. These attributes and various models developed in guinea pigs are discussed.
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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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11
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Adriaensen D, Brouns I, Pintelon I, De Proost I, Timmermans JP. Evidence for a role of neuroepithelial bodies as complex airway sensors: comparison with smooth muscle-associated airway receptors. J Appl Physiol (1985) 2006; 101:960-70. [PMID: 16741263 DOI: 10.1152/japplphysiol.00267.2006] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The epithelium of intrapulmonary airways in many species harbors diffusely spread innervated groups of neuroendocrine cells, called neuroepithelial bodies (NEBs). Data on the location, morphology, and chemical coding of NEBs in mammalian lungs are abundant, but none of the proposed functions has so far been fully established. Besides C-fiber afferents, slowly adapting stretch receptors, and rapidly adapting stretch receptors, recent reviews have added NEBs to the list of presumed sensory receptors in intrapulmonary airways. Physiologically, the innervation of NEBs, however, remains enigmatic. This short overview summarizes our present understanding of the chemical coding and exact location of the receptor end organs of myelinated vagal airway afferents in intrapulmonary airways. The profuse populations that selectively contact complex pulmonary NEB receptors are compared with the much smaller group of smooth muscle-associated airway receptors. The main objective of our contribution was to stimulate the idea that the different populations of myelinated vagal afferents that selectively innervate intraepithelial pulmonary NEBs may represent subpopulations of the extensive group of known electrophysiologically characterized myelinated vagal airway receptors. Future efforts should be directed toward finding out which airway receptor groups are selectively coupled to the complex NEB receptors.
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Affiliation(s)
- Dirk Adriaensen
- Laboratory of Cell Biology & Histology, Dept. of Veterinary Sciences, University of Antwerp, BE-2020 Antwerp, Belgium.
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12
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Abstract
Pulmonary neuroendocrine cells (PNECs) have been around for 60 years in the scientific literature, although phylogenetically they are ancient. Their traditionally ascribed functions include chemoreception and regulation of lung maturation and growth. There is recent evidence that neuroendocrine (NE) differentiation in the lung is regulated by genes and pathways that are conserved in the development of the nervous system from Drosophila to humans (such as achaete-scute homolog-1), or implicated in the carcinogenesis of the nervous or NE system (such as the retinoblastoma tumor suppressor gene). In addition, complex neural networks are in place to regulate chemosensory and other functions. Even solitary PNECs appear to be innervated. For the first time ever, we have mouse models for lung NE carcinomas, including the most common and virulent small cell lung carcinoma. Moreover, PNECs may be important for inflammatory responses, and pivotal for lung stem cell niches. These discoveries signify an exciting new era for PNECs and are likely to have therapeutic and diagnostic applications.
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Affiliation(s)
- R Ilona Linnoila
- Cell and Cancer Biology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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Pan J, Luk C, Kent G, Cutz E, Yeger H. Pulmonary neuroendocrine cells, airway innervation, and smooth muscle are altered in Cftr null mice. Am J Respir Cell Mol Biol 2006; 35:320-6. [PMID: 16614351 PMCID: PMC2643285 DOI: 10.1165/rcmb.2005-0468oc] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The amine- and peptide-producing pulmonary neuroendocrine cells (PNEC) are widely distributed within the airway mucosa of mammalian lung as solitary cells and innervated clusters, neuroepithelial bodies (NEB), which function as airway O2 sensors. These cells express Cftr and hence could play a role in the pathophysiology of cystic fibrosis (CF) lung disease. We performed confocal microscopy and morphometric analysis on lung sections from Cftr-/- (null), Cftr+/+, and Cftr+/- (control) mice at developmental stages E20, P5, P9, and P30 to determine the distribution, frequency, and innervation of PNEC/NEB, innervation and cell mass of airway smooth muscle, and neuromuscular junctions using synaptic vesicle protein 2, smooth muscle actin, and synaptophysin markers, respectively. The mean number of PNEC/NEB in Cftr-/- mice was significantly reduced compared with control mice at E20, whereas comparable or increased numbers were observed postnatally. NEB cells in Cftr null mice showed a significant reduction in intracorpuscular nerve endings compared with control mice, which is consistent with an intrinsic abnormality of the PNEC system. The airways of Cftr-/- mice showed reduced density (approximately 20-30%) of smooth muscle innervation, decreased mean airway smooth muscle mass (approximately 35%), and reduced density (approximately 20%) of nerve endings compared with control mice. We conclude that the airways of Cftr-/- mice exhibit heretofore unappreciated structural alterations affecting cellular and neural components of the PNEC system and airway smooth muscle and its innervation resulting in blunted O2 sensing and reduced airway tonus. Cftr could play a role in the development of the PNEC system, lung innervation, and airway smooth muscle.
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Affiliation(s)
- Jie Pan
- Division of Pathology, Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
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Putnam RW, Filosa JA, Ritucci NA. Cellular mechanisms involved in CO(2) and acid signaling in chemosensitive neurons. Am J Physiol Cell Physiol 2004; 287:C1493-526. [PMID: 15525685 DOI: 10.1152/ajpcell.00282.2004] [Citation(s) in RCA: 221] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An increase in CO(2)/H(+) is a major stimulus for increased ventilation and is sensed by specialized brain stem neurons called central chemosensitive neurons. These neurons appear to be spread among numerous brain stem regions, and neurons from different regions have different levels of chemosensitivity. Early studies implicated changes of pH as playing a role in chemosensitive signaling, most likely by inhibiting a K(+) channel, depolarizing chemosensitive neurons, and thereby increasing their firing rate. Considerable progress has been made over the past decade in understanding the cellular mechanisms of chemosensitive signaling using reduced preparations. Recent evidence has pointed to an important role of changes of intracellular pH in the response of central chemosensitive neurons to increased CO(2)/H(+) levels. The signaling mechanisms for chemosensitivity may also involve changes of extracellular pH, intracellular Ca(2+), gap junctions, oxidative stress, glial cells, bicarbonate, CO(2), and neurotransmitters. The normal target for these signals is generally believed to be a K(+) channel, although it is likely that many K(+) channels as well as Ca(2+) channels are involved as targets of chemosensitive signals. The results of studies of cellular signaling in central chemosensitive neurons are compared with results in other CO(2)- and/or H(+)-sensitive cells, including peripheral chemoreceptors (carotid body glomus cells), invertebrate central chemoreceptors, avian intrapulmonary chemoreceptors, acid-sensitive taste receptor cells on the tongue, and pain-sensitive nociceptors. A multiple factors model is proposed for central chemosensitive neurons in which multiple signals that affect multiple ion channel targets result in the final neuronal response to changes in CO(2)/H(+).
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Affiliation(s)
- Robert W Putnam
- Department of Anatomy and Physiology, Wright State University School of Medicine, 3640 Colonel Glenn Highway, Dayton, OH 45435, USA.
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15
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Adriaensen D, Brouns I, Van Genechten J, Timmermans JP. Functional morphology of pulmonary neuroepithelial bodies: extremely complex airway receptors. THE ANATOMICAL RECORD. PART A, DISCOVERIES IN MOLECULAR, CELLULAR, AND EVOLUTIONARY BIOLOGY 2003; 270:25-40. [PMID: 12494487 DOI: 10.1002/ar.a.10007] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Innervated groups of neuroendocrine cells, called neuroepithelial bodies (NEBs), are diffusely spread in the epithelium of intrapulmonary airways in many species. Our present understanding of the morphology of NEBs in mammalian lungs is comprehensive, but none of the proposed functional hypotheses have been proven conclusively. In recent reviews on airway innervation, NEBs have been added to the list of presumed physiological lung receptors. Microscopic data on the innervation of NEBs, however, have given rise to conflicting interpretations. Using neuronal tracing, denervation, and immunostaining, we recently demonstrated that the innervation of NEBs is much more complex than the almost unique vagal nodose sensory innervation suggested by other authors. The aim of the present work is to summarize our present understanding about the origin and chemical coding of the profuse nerve terminals that selectively contact pulmonary NEBs. A thorough knowledge of the complex interactions between the neuroendocrine cells and at least five different nerve fiber populations is essential for defining the position(s) of NEBs among the many pulmonary receptors characterized by lung physiologists.
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Affiliation(s)
- Dirk Adriaensen
- Department of Biomedical Sciences, University of Antwerp-RUCA, Antwerp, Belgium.
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Abstract
Neuroendocrine carcinoma of the nasopharynx was diagnosed in a 9-year-old male Golden Retriever. The mass was identified by computed tomography of the nasal cavity and nasopharyngoscopy, and it was surgically excised. Histologic, cytochemical, and electromicroscopic examination of specimens confirmed the type of tumor. The dog was clincally improved for 150 days but was then reexamined because of respiratory difficulty and poor appetite. Thoracic radiographs revealed multiple nodules in all lung lobes, and ultrasonography revealed a mass in the spleen. The dog died the next day.
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Affiliation(s)
- A K Patnaik
- Department of Pathology, Animal Medical Center, New York, NY 10021, USA
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Elizegi E, Pino I, Vicent S, Blanco D, Saffiotti U, Montuenga LM. Hyperplasia of alveolar neuroendocrine cells in rat lung carcinogenesis by silica with selective expression of proadrenomedullin-derived peptides and amidating enzymes. J Transl Med 2001; 81:1627-38. [PMID: 11742033 DOI: 10.1038/labinvest.3780376] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Pulmonary neuroendocrine (NE) cells are found as clusters called neuroepithelial bodies (NEBs) or as single cells scattered in the respiratory epithelium. They express a variety of bioactive peptides, and they are thought to be the origin of NE lung tumors. Proadrenomedullin N-terminal 20 peptide (PAMP) is a peptide derived from the same precursor as adrenomedullin (AM). AM and PAMP are C-terminally amidated during their processing by a well-characterized amidating enzyme, peptidylglycine alpha-amidating monooxygenase (PAM). We explored AM, PAMP, and PAM expression as markers for NE hyperplasia in three rodent species (Fischer 344 rats, Syrian golden hamsters, and A/J mice) after a single intratracheal instillation of crystalline silica (quartz), which was previously found to induce different reactions in the three species. Rats developed a marked silicosis, with alveolar and bronchiolar hyperplasia and formation of peripheral lung epithelial tumors. Mice developed a moderate degree of silicosis, but not epithelial hyperplasia or tumors. Hamsters showed dust-storage lesions, but not silicosis or tumors. NE cells were immunolabeled for calcitonin gene-related peptide (CGRP), AM, PAMP, and PAM in serial sections of each lung. The numbers of positive NEBs per lung area and positive cells per NEB were quantified. A marked hyperplastic reaction in the NEBs of silica treated rats occurred only in alveolar NEBs, but not in bronchiolar NEBs. From Month 11 onwards, there were marked differences in the number of alveolar NEBs per section and in the number of cells per alveolar NEB immunoreactive for CGRP. No hyperplastic NE cell reaction was observed in silica-treated mice and hamsters. Significant PAMP and PAM expression was seen only in rat hyperplastic alveolar and in bronchiolar NEBs from Month 11 onwards. In E18, rat fetal lung NEBs were found to be strongly positive for PAMP and PAM.
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Affiliation(s)
- E Elizegi
- Department of Histology and Pathology, University of Navarra, Pamplona, Spain
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Van Lommel A, Bollé T, Fannes W, Lauweryns JM. The pulmonary neuroendocrine system: the past decade. ARCHIVES OF HISTOLOGY AND CYTOLOGY 1999; 62:1-16. [PMID: 10223738 DOI: 10.1679/aohc.62.1] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The pulmonary neuroendocrine system consists of specialized airway endocrine epithelial cells, associated with nerve fibres. The epithelial cells, the pulmonary neuroendocrine cells (PNEC), can be solitary or clustered to form neuroepithelial bodies (NEB). During the last thirty years, the pulmonary neuroendocrine system has been intensively investigated and much knowledge of its function has been obtained. This text reviews work which dates from the last ten years. In this period, the picture of the pulmonary neuroendocrine system we previously had, has not fundamentally changed. The pulmonary neuroendocrine system is still regarded as an oxygen sensitive chemoreceptor with local and reflex-mediated regulatory functions, and as a regulator of airway growth and development. Continuing research has much more refined this picture. This text reviews several aspects of the pulmonary neuroendocrine system: phylogeny, the amine and peptide content of its epithelial cells, ontogeny and influence on lung development, the influence of hypoxia and nonhypoxic stimuli, immunomodulatory function, innervation and pathology. Among the discoveries of the past decade, three stand out prominently because of their great significance: additional proof that the neural component of the pulmonary neuroendocrine system is sensory, sound experimental evidence that PNEC stimulate airway epithelial cell differentiation and the discovery of a specific membrane oxygen receptor in the PNEC.
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Affiliation(s)
- A Van Lommel
- Laboratory of Pathological Anatomy, Medical Faculty, Katholieke Universiteit te Leuven, Belgium.
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