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Zhang N, Xu J, Jiang C, Lu S. Neuro-Immune Regulation in Inflammation and Airway Remodeling of Allergic Asthma. Front Immunol 2022; 13:894047. [PMID: 35784284 PMCID: PMC9245431 DOI: 10.3389/fimmu.2022.894047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/23/2022] [Indexed: 12/16/2022] Open
Abstract
Allergic asthma is a common chronic inflammation of the airways and causes airway remodeling eventually. For a long time, investigators have been focusing on the immunological mechanism of asthma. However, in recent years, the role of neuro-regulation in the occurrence of asthma has gradually attracted investigators’ attention. In this review, we firstly describe neuro-immune regulation in inflammation of allergic asthma from two aspects: innate immunity and adaptive immunity. Secondly, we introduce neuro-immune regulation in airway remodeling of asthma. Finally, we prospect the role of pulmonary neuroendocrine cells in the development of asthma. In general, the amount of researches is limited. Further researches on the neural regulation during the occurrence of asthma will help us clarify the mechanism of asthma more comprehensively and find more effective ways to prevent and control asthma.
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Affiliation(s)
- Ning Zhang
- National Joint Engineering Research Center of Biodiagnostics and Biotherapy, Second Affiliated Hospital, Xi’an Jiaotong University, Xi’an, China
- Key Laboratory of Environment and Genes Related to Diseases, Xi’an Jiaotong University, Ministry of Education, Xi’an, China
- Institute of Molecular and Translational Medicine (IMTM), Xi’an Jiaotong University Health Science Center, Xi’an, China
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, China
| | - Jing Xu
- Key Laboratory of Environment and Genes Related to Diseases, Xi’an Jiaotong University, Ministry of Education, Xi’an, China
- Institute of Molecular and Translational Medicine (IMTM), Xi’an Jiaotong University Health Science Center, Xi’an, China
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, China
| | - Congshan Jiang
- National Regional Children’s Medical Center (Northwest), Key Laboratory of Precision Medicine to Pediatric Diseases of Shaanxi Province, Xi’an Key Laboratory of Children’s Health and Diseases, Shaanxi Institute for Pediatric Diseases, Xi’an Children’s Hospital, Affiliated Children’s Hospital of Xi’an Jiaotong University, Xi’an, China
- *Correspondence: Congshan Jiang, ; Shemin Lu,
| | - Shemin Lu
- National Joint Engineering Research Center of Biodiagnostics and Biotherapy, Second Affiliated Hospital, Xi’an Jiaotong University, Xi’an, China
- Key Laboratory of Environment and Genes Related to Diseases, Xi’an Jiaotong University, Ministry of Education, Xi’an, China
- Institute of Molecular and Translational Medicine (IMTM), Xi’an Jiaotong University Health Science Center, Xi’an, China
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, China
- National Regional Children’s Medical Center (Northwest), Key Laboratory of Precision Medicine to Pediatric Diseases of Shaanxi Province, Xi’an Key Laboratory of Children’s Health and Diseases, Shaanxi Institute for Pediatric Diseases, Xi’an Children’s Hospital, Affiliated Children’s Hospital of Xi’an Jiaotong University, Xi’an, China
- *Correspondence: Congshan Jiang, ; Shemin Lu,
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Cellular and functional heterogeneity of the airway epithelium. Mucosal Immunol 2021; 14:978-990. [PMID: 33608655 PMCID: PMC7893625 DOI: 10.1038/s41385-020-00370-7] [Citation(s) in RCA: 101] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/15/2020] [Accepted: 12/07/2020] [Indexed: 02/07/2023]
Abstract
The airway epithelium protects us from environmental insults, which we encounter with every breath. Not only does it passively filter large particles, it also senses potential danger and alerts other cells, including immune and nervous cells. Together, these tissues orchestrate the most appropriate response, balancing the need to eliminate the danger with the risk of damage to the host. Each cell subset within the airway epithelium plays its part, and when impaired, may contribute to the development of respiratory disease. Here we highlight recent advances regarding the cellular and functional heterogeneity along the airway epithelium and discuss how we can use this knowledge to design more effective, targeted therapeutics.
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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: 15] [Impact Index Per Article: 3.8] [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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Abstract
Pulmonary neuroendocrine cells (PNEC) are widely distributed throughout the airway mucosa of mammalian lung as solitary cells and as distinctive innervated clusters, neuroepithelial bodies (NEB). These cells differentiate early during lung development and are more prominent in fetal/neonatal lungs compared to adults. PNEC/NEB cells produce biogenic amine (serotonin) and a variety of peptides (i.e., bombesin) involved in regulation of lung function. During the perinatal period, NEB are thought to function as airway O(2)/CO(2) sensors. Increased numbers of PNEC/NEBs have been observed in a variety of perinatal and postnatal lung disorders. Recent advances in cellular and molecular biology of these cells, as they relate to perinatal and postnatal lung disorders associated with PNEC/NEB cell hyperplasia are reviewed and their possible role in pulmonary pathobiology discussed (WC 125).
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Affiliation(s)
- Ernest Cutz
- Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, 555 University Ave, Toronto, Ontario, Canada M5G1x8; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
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Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia of the Lung (DIPNECH): Current Best Evidence. Lung 2015; 193:659-67. [DOI: 10.1007/s00408-015-9755-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 06/17/2015] [Indexed: 12/11/2022]
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Abstract
The differential diagnosis of diffuse lung disease in children differs considerably from adults, and analysis of pediatric lung biopsies may prove challenging for pathologists with more extensive exposure to adult lung biopsies. Biopsy diagnosis of pediatric lung disease continues to evolve as new pathologic entities are recognized and new genetic determinants of disease are discovered. This article describes the clinical characteristics, pathologic features, and differential diagnosis of challenging and recently described entities in pediatric lung disease. The specific entities discussed include alveolar capillary dysplasia, genetic disorders of surfactant metabolism, pulmonary interstitial glycogenosis, and neuroendocrine cell hyperplasia of infancy.
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Affiliation(s)
- Megan K Dishop
- Department of Pathology, B120, The Children's Hospital, University of Colorado-Denver School of Medicine, 13123 East 16th Avenue, Aurora, CO 80045, USA.
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Dishop MK. Diagnostic Pathology of Diffuse Lung Disease in Children. PEDIATRIC ALLERGY, IMMUNOLOGY, AND PULMONOLOGY 2010; 23:69-85. [PMID: 22332032 PMCID: PMC3269262 DOI: 10.1089/ped.2010.0007] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Accepted: 03/20/2010] [Indexed: 11/13/2022]
Abstract
The pathologic classification of diffuse lung disease in children and adolescents has undergone revision in recent years in response to rapid developments and new discoveries in the field. A number of important advancements have been made in the last 10 years including the description of new genetic mutations causing severe lung disease in infants and children, as well as the description of new pathologic entities in infants. These recently described entities, including ABCA3 surfactant disorders, pulmonary interstitial glycogenosis, and neuroendocrine cell hyperplasia of infancy, are being recognized with increasing frequency. This review will include brief discussion of the etiology and pathogenesis of the major groups of diffuse lung disease in children. Histopathologic features are discussed for each of the major categories of diffuse lung disease in children, beginning with the genetic, developmental, and alveolar growth disorders common in infancy, followed by brief discussion of airway diseases, immunologic diseases, and pulmonary vascular diseases seen more commonly in older children. A protocol for handling pediatric wedge lung biopsies is also discussed, which optimizes the diagnostic yield of lung biopsies in this population.
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Affiliation(s)
- Megan K Dishop
- Department of Pathology, The Children's Hospital and University of Colorado-Denver , Aurora, Colorado
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Segura P, Vargas MH, Córdoba-Rodríguez G, Chávez J, Arreola JL, Campos-Bedolla P, Ruiz V, García-Hernández LM, Méndez C, Montaño LM. Role of 5-HT2A, 5-HT4 and 5-HT7 receptors in the antigen-induced airway hyperresponsiveness in guinea-pigs. Clin Exp Allergy 2009; 40:327-38. [PMID: 19995401 DOI: 10.1111/j.1365-2222.2009.03412.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND A possible role of 5-hydroxytryptamine (5-HT) in the origin of antigen-induced airway hyperresponsiveness (AI-AHR) has been scarcely investigated. OBJECTIVE To explore the participation of different 5-HT receptors in the development of AI-AHR in guinea-pigs. METHODS Lung resistance was measured in anaesthetized guinea-pigs sensitized to ovalbumin (OVA). Dose-response curves to intravenous (i.v.) acetylcholine (ACh) were performed before and 1 h after antigenic challenge and expressed as the 200% provocative dose (PD(200)). Organ bath experiments, confocal microscopy and RT-PCR were additionally used. The 5-HT content in lung homogenates was measured by HPLC. RESULTS Antigenic challenge significantly decreased PD(200), indicating the development of AI-AHR. This hyperresponsiveness was abolished by a combination of methiothepin (5-HT(1)/5-HT(2)/5-HT(5)/5-HT(6)/5-HT(7) receptors antagonist) and tropisetron (5-HT(3)/5-HT(4) antagonist). Other 5-HT receptor antagonists showed three different patterns of response. Firstly, WAY100135 (5-HT(1A) antagonist) and ondansetron (5-HT(3) antagonist) did not modify the AI-AHR. Secondly, SB269970 (5-HT(7) antagonist), GR113808 (5-HT(4) antagonist), tropisetron or methiothepin abolished the AI-AHR. Thirdly, ketanserin (5-HT(2A) antagonist) produced airway hyporresponsiveness. Animals with bilateral vagotomy did not develop AI-AHR. Experiments in tracheal rings showed that pre-incubation with LP44 or cisapride (agonists of 5-HT(7) and 5-HT(4) receptors, respectively) induced a significant increase of the cholinergic contractile response to the electrical field stimulation. In sensitized lung parenchyma strips, ketanserin diminished the contractile responses to ACh. Sensitization was associated with a ninefold increase in the 5-HT content of lung homogenates. Confocal microscopy showed that sensitization enhanced the immunolabelling and co-localization of nicotinic receptor and 5-HT in airway epithelium, probably located in pulmonary neuroendocrine cells (PNECs). RT-PCR demonstrated that neither sensitization nor antigen challenge modified the 5-HT(2A) receptor mRNA levels. CONCLUSIONS Our results suggested that 5-HT was involved in the development of AI-AHR to ACh in guinea-pigs. Specifically, 5-HT(2A), 5-HT(4) and 5-HT(7) receptors seem to be particularly involved in this phenomenon. Participation of 5-HT might probably be favoured by the enhancement of the PNECs 5-HT content observed after sensitization.
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Affiliation(s)
- P Segura
- Departamento de Investigación en Hiperreactividad Bronquial, Instituto Nacional de Enfermedades Respiratorias, México DF, México
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Cutz E, Yeger H, Pan J. Pulmonary neuroendocrine cell system in pediatric lung disease-recent advances. Pediatr Dev Pathol 2007; 10:419-35. [PMID: 18001162 DOI: 10.2350/07-04-0267.1] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Accepted: 09/04/2007] [Indexed: 11/20/2022]
Abstract
The airway epithelium of human and animal lungs contains highly specialized pulmonary neuroendocrine cells (PNEC), distributed as solitary cells and as innervated clusters, neuroepithelial bodies (NEB). The designation "PNEC system" stems from the expression of both neural and endocrine cell phenotypes, including the synthesis and release of amine (serotonin, 5-HT) and a variety of neuropeptides (that is, bombesin). The role and function of PNEC in the lung have remained a subject of speculation for many years. During the last decade, studies using modern techniques of cellular and molecular biology revealed a complex functional role for PNEC, beginning during the early stages of lung development as modulators of fetal lung growth and differentiation and at the time of birth as airway O2 sensors involved in neonatal adaptation. Postnatally and beyond, PNEC/NEB are providers of a lung stem cell niche that is important in airway epithelial regeneration and lung carcinogenesis. The focus of this review is to present and discuss recent findings pertaining to the responses of PNEC to intrauterine environmental stimuli, ontogeny and molecular regulation of PNEC differentiation, innervation of NEB, and their role as airway chemoreceptors, including mechanisms of O2 sensing and chemotransmission of hypoxia stimulus. Abnormalities of PNEC/NEB have been reported in a variety of pediatric pulmonary disorders but the clinical significance or the mechanisms involved are unknown. The discussion on the possible role of PNEC/NEB in the pathogenesis and pathobiology of pediatric lung diseases includes congenital lung disorders, bronchopulmonary dysplasia, disorders of respiratory control, neuroendocrine hyperplasia of infancy, cystic fibrosis, bronchial asthma, and pulmonary hypertension.
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Affiliation(s)
- Ernest Cutz
- Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto,ON, Canada.
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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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Deterding RR, Pye C, Fan LL, Langston C. Persistent tachypnea of infancy is associated with neuroendocrine cell hyperplasia. Pediatr Pulmonol 2005; 40:157-65. [PMID: 15965897 DOI: 10.1002/ppul.20243] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
We sought to determine the clinical course and histologic findings in lung biopsies from a group of children who presented with signs and symptoms of interstitial lung disease (ILD) without identified etiology. Patients were identified from the pathology files at the Texas Children's Hospital who presented below age 2 years with persistent tachypnea, hypoxia, retractions, or respiratory crackles, and with nonspecific and nondiagnostic lung biopsy findings. Age-matched lung biopsy controls were also identified. Their clinical courses were retrospectively reviewed. Biopsies were reviewed, and immunostaining with antibodies to neuroendocrine cells was done. Fifteen pediatric ILD patients and four control patients were identified for inclusion in the study. Clinically, the mean onset of symptoms was 3.8 months (range, 0-11 months). Radiographs demonstrated hyperinflation, interstitial markings, and ground-glass densities. Oxygen was initially required for prolonged periods, and medication trials did not eliminate symptoms. After a mean of 5 years, no deaths had occurred, and patients had improved. On review of the lung biopsies, all had a similar appearance, with few abnormalities noted. Immunostaining with antibodies to neuroendocrine cell products showed consistently increased bombesin staining. Subsequent morphometric analysis showed that immunoreactivity for bombesin and serotonin was significantly increased over age-matched controls. In conclusion, we believe this may represent a distinct group of pediatric patients defined by the absence of known lung diseases, clinical signs and symptoms of ILD, and idiopathic neuroendocrine cell hyperplasia of infancy. These findings may be important for the evaluation of ILD in young children.
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Affiliation(s)
- Robin R Deterding
- Pediatric Pulmonary Section, Department of Pediatrics, University of Colorado Health Science Center, Children's Hospital, Denver, Colorado 80218, USA.
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Schuller HM, Plummer HK, Jull BA. Receptor-mediated effects of nicotine and its nitrosated derivative NNK on pulmonary neuroendocrine cells. THE ANATOMICAL RECORD. PART A, DISCOVERIES IN MOLECULAR, CELLULAR, AND EVOLUTIONARY BIOLOGY 2003; 270:51-8. [PMID: 12494489 DOI: 10.1002/ar.a.10019] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Pulmonary neuroendocrine cells (PNECs) have been implicated in the development of small cell lung carcinoma (SCLC) and pediatric asthma, and smoking is a risk factor for both diseases. We as well as others have shown that the alpha(7) nicotinic acetylcholine receptor (alpha(7) nAChR) regulates the release of 5-hydroxytryptamine (5-HT, serotonin) in PNECs and SCLC. Serotonin is an autocrine growth factor for PNECs and SCLC and acts as broncho-constrictor. We found that nicotine and its nitrosated carcinogenic derivative 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) bind to the alpha(7) nAChR in SCLC and PNECs, resulting in the influx of Ca(2+), release of 5-HT, and activation of a mitogenic pathway mediated by protein kinase C (PKC), Raf-1, mitogen activated protein kinase (MAPK) and c-myc. Exposure to 10% CO(2) acted synergistically. Unstimulated SCLC cells from smokers demonstrated high base levels of 5-HT release and of individual downstream signaling components in comparison to PNECs. Subchronic exposure of PNECs to NNK up-regulated the alpha(7) nAChR and its associated serotonergic mitogenic pathway in PNECs, an effect that may contribute to the development of SCLC in smokers and pediatric asthma in children of mothers who smoke.
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Affiliation(s)
- Hildegard M Schuller
- Department of Pathology, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee 37996, USA.
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Reynolds SD, Giangreco A, Power JH, Stripp BR. Neuroepithelial bodies of pulmonary airways serve as a reservoir of progenitor cells capable of epithelial regeneration. THE AMERICAN JOURNAL OF PATHOLOGY 2000; 156:269-78. [PMID: 10623675 PMCID: PMC1868636 DOI: 10.1016/s0002-9440(10)64727-x] [Citation(s) in RCA: 285] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Remodeling of the conducting airway epithelium is a common finding in the chronically injured lung and has been associated with increased risk for developing lung cancer. Pulmonary neuroendocrine cells and clusters of these cells termed neuroepithelial bodies (NEBs) play a central role in each of these processes. We previously developed an adult mouse model of airway injury and repair in which epithelial regeneration after naphthalene-induced Clara cell ablation occurred preferentially at airway branch points and gave rise to nascent Clara cells. Continued repair was accompanied by NEB hyperplasia. We now provide the following evidence that the NEB microenvironment serves as a source of airway progenitor cells that contribute to focal regeneration of the airway epithelium: 1) nascent Clara cells and NEBs localize to the same spatial domain; 2) within NEB, both Clara cell secretory protein- and calcitonin gene-related peptide-immunopositive cells are proliferative; 3) the NEB microenvironment of both the steady-state and repairing lung includes cells that are dually immunopositive for Clara cell secretory protein and calcitonin gene-related peptide, which were previously identified only within the embryonic lung; and 4) NEBs harbor variant Clara cells deficient in cytochrome P450 2F2-immunoreactive protein. These data suggest that the NEB microenvironment is a reservoir of pollutant-resistant progenitor cells responsive to depletion of an abundant airway progenitor such as the Clara cell.
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Affiliation(s)
- S D Reynolds
- Department of Environmental Medicine, University of Rochester, Rochester, New York 14642, USA
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