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Hollenhorst MI, Husnik T, Zylka M, Duda N, Flockerzi V, Tschernig T, Maxeiner S, Krasteva-Christ G. Human airway tuft cells influence the mucociliary clearance through cholinergic signalling. Respir Res 2023; 24:267. [PMID: 37925434 PMCID: PMC10625704 DOI: 10.1186/s12931-023-02570-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 10/20/2023] [Indexed: 11/06/2023] Open
Abstract
BACKGROUND Airway tuft cells, formerly called brush cells have long been described only morphologically in human airways. More recent RNAseq studies described a chemosensory cell population, which includes tuft cells, by a distinct gene transcription signature. Yet, until which level in the tracheobronchial tree in native human airway epithelium tuft cells occur and if they function as regulators of innate immunity, e.g., by regulating mucociliary clearance, remained largely elusive. METHODS We performed immunohistochemistry, RT-PCR and immunoblotting analyses for various tuft cell markers to confirm the presence of this cell type in human tracheal samples. Immunohistochemistry was conducted to study the distribution of tuft cells along the intrapulmonary airways in humans. We assessed the influence of bitter substances and the taste transduction pathway on mucociliary clearance in mouse and human tracheal samples by measuring particle transport speed. RESULTS Tuft cells identified by the expression of their well-established marker POU class 2 homeobox 3 (POU2F3) were present from the trachea to the bronchioles. We identified choline acetyltransferase in POU2F3 expressing cells as well as the transient receptor potential melastatin 5 (TRPM5) channel in a small population of tracheal epithelial cells with morphological appearance of tuft cells. Application of bitter substances, such as denatonium, led to an increase in mucociliary clearance in human tracheal preparations. This was dependent on activation of the TRPM5 channel and involved cholinergic and nitric oxide signalling, indicating a functional role for human tuft cells in the regulation of mucociliary clearance. CONCLUSIONS We were able to detect tuft cells in the tracheobronchial tree down to the level of the bronchioles. Moreover, taste transduction and cholinergic signalling occur in the same cells and regulate mucociliary clearance. Thus, tuft cells are potentially involved in the regulation of innate immunity in human airways.
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Affiliation(s)
| | - Thomas Husnik
- Institute of Anatomy and Cell Biology, Saarland University, Homburg, Germany
| | - Malin Zylka
- Institute of Anatomy and Cell Biology, Saarland University, Homburg, Germany
| | - Nele Duda
- Institute of Anatomy and Cell Biology, Saarland University, Homburg, Germany
| | - Veit Flockerzi
- Institute for Experimental and Clinical Pharmacology and Toxicology, Preclinical Center for Molecular Signaling, Saarland University, Homburg, Germany
| | - Thomas Tschernig
- Institute of Anatomy and Cell Biology, Saarland University, Homburg, Germany
| | - Stephan Maxeiner
- Institute of Anatomy and Cell Biology, Saarland University, Homburg, Germany
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2
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Kouakou YI, Lee RJ. Interkingdom Detection of Bacterial Quorum-Sensing Molecules by Mammalian Taste Receptors. Microorganisms 2023; 11:1295. [PMID: 37317269 PMCID: PMC10221136 DOI: 10.3390/microorganisms11051295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 05/11/2023] [Accepted: 05/13/2023] [Indexed: 06/16/2023] Open
Abstract
Bitter and sweet taste G protein-coupled receptors (known as T2Rs and T1Rs, respectively) were originally identified in type II taste cells on the tongue, where they signal perception of bitter and sweet tastes, respectively. Over the past ~15 years, taste receptors have been identified in cells all over the body, demonstrating a more general chemosensory role beyond taste. Bitter and sweet taste receptors regulate gut epithelial function, pancreatic β cell secretion, thyroid hormone secretion, adipocyte function, and many other processes. Emerging data from a variety of tissues suggest that taste receptors are also used by mammalian cells to "eavesdrop" on bacterial communications. These receptors are activated by several quorum-sensing molecules, including acyl-homoserine lactones and quinolones from Gram-negative bacteria such as Pseudomonas aeruginosa, competence stimulating peptides from Streptococcus mutans, and D-amino acids from Staphylococcus aureus. Taste receptors are an arm of immune surveillance similar to Toll-like receptors and other pattern recognition receptors. Because they are activated by quorum-sensing molecules, taste receptors report information about microbial population density based on the chemical composition of the extracellular environment. This review summarizes current knowledge of bacterial activation of taste receptors and identifies important questions remaining in this field.
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Affiliation(s)
- Yobouet Ines Kouakou
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA;
| | - Robert J. Lee
- Department of Otorhinolaryngology and Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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3
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Du Y, Gao H, He C, Xin S, Wang B, Zhang S, Gong F, Yu X, Pan L, Sun F, Wang W, Xu J. An update on the biological characteristics and functions of tuft cells in the gut. Front Cell Dev Biol 2023; 10:1102978. [PMID: 36704202 PMCID: PMC9872863 DOI: 10.3389/fcell.2022.1102978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 12/27/2022] [Indexed: 01/11/2023] Open
Abstract
The intestine is a powerful digestive system and one of the most sophisticated immunological organs. Evidence shows that tuft cells (TCs), a kind of epithelial cell with distinct morphological characteristics, play a significant role in various physiological processes. TCs can be broadly categorized into different subtypes depending on different molecular criteria. In this review, we discuss its biological properties and role in maintaining homeostasis in the gastrointestinal tract. We also emphasize its relevance to the immune system and highlight its powerful influence on intestinal diseases, including inflammations and tumors. In addition, we provide fresh insights into future clinical diagnostic and therapeutic strategies related to TCs.
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Affiliation(s)
- Yixuan Du
- Department of Oral Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Han Gao
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Chengwei He
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Shuzi Xin
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Boya Wang
- Undergraduate Student of 2018 Eight Program of Clinical Medicine, Peking University People’s Hospital, Beijing, China
| | - Sitian Zhang
- Department of Clinical Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Fengrong Gong
- Department of Clinical Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Xinyi Yu
- Department of Clinical Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Luming Pan
- Department of Clinical Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Fanglin Sun
- Department of Laboratory Animal Research, Xuan Wu Hospital, Capital Medical University, Beijing, China
| | - Wen Wang
- Department of Laboratory Animal Research, Xuan Wu Hospital, Capital Medical University, Beijing, China
| | - Jingdong Xu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China,*Correspondence: Jingdong Xu,
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4
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Ting HA, von Moltke J. The Immune Function of Tuft Cells at Gut Mucosal Surfaces and Beyond. THE JOURNAL OF IMMUNOLOGY 2019; 202:1321-1329. [PMID: 30782851 DOI: 10.4049/jimmunol.1801069] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 09/21/2018] [Indexed: 12/25/2022]
Abstract
Tuft cells were first discovered in epithelial barriers decades ago, but their function remained unclear until recently. In the last 2 years, a series of studies has provided important advances that link tuft cells to infectious diseases and the host immune responses. Broadly, a model has emerged in which tuft cells use chemosensing to monitor their surroundings and translate environmental signals into effector functions that regulate immune responses in the underlying tissue. In this article, we review the current understanding of tuft cell immune function in the intestines, airways, and thymus. In particular, we discuss the role of tuft cells in type 2 immunity, norovirus infection, and thymocyte development. Despite recent advances, many fundamental questions about the function of tuft cells in immunity remain to be answered.
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Affiliation(s)
- Hung-An Ting
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98109
| | - Jakob von Moltke
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98109
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5
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Carey RM, Lee RJ. Taste Receptors in Upper Airway Innate Immunity. Nutrients 2019; 11:nu11092017. [PMID: 31466230 PMCID: PMC6770031 DOI: 10.3390/nu11092017] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 08/19/2019] [Accepted: 08/22/2019] [Indexed: 02/07/2023] Open
Abstract
Taste receptors, first identified on the tongue, are best known for their role in guiding our dietary preferences. The expression of taste receptors for umami, sweet, and bitter have been demonstrated in tissues outside of the oral cavity, including in the airway, brain, gastrointestinal tract, and reproductive organs. The extra-oral taste receptor chemosensory pathways and the endogenous taste receptor ligands are generally unknown, but there is increasing data suggesting that taste receptors are involved in regulating some aspects of innate immunity, and may potentially control the composition of the nasal microbiome in healthy individuals or patients with upper respiratory diseases like chronic rhinosinusitis (CRS). For this reason, taste receptors may serve as potential therapeutic targets, providing alternatives to conventional antibiotics. This review focuses on the physiology of sweet (T1R) and bitter (T2R) taste receptors in the airway and their activation by secreted bacterial products. There is particular focus on T2R38 in sinonasal ciliated cells, as well as the sweet and bitter receptors found on specialized sinonasal solitary chemosensory cells. Additionally, this review explores the impact of genetic variations in these receptors on the differential susceptibility of patients to upper airway infections, such as CRS.
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Affiliation(s)
- Ryan M Carey
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Robert J Lee
- Department of Otorhinolaryngology and Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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6
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Nevo S, Kadouri N, Abramson J. Tuft cells: From the mucosa to the thymus. Immunol Lett 2019; 210:1-9. [PMID: 30904566 DOI: 10.1016/j.imlet.2019.02.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 02/10/2019] [Accepted: 02/11/2019] [Indexed: 02/06/2023]
Abstract
Tuft cells are epithelial chemosensory cells with unique morphological and molecular characteristics, the most noticeable of which is a tuft of long and thick microvilli on their apical side, as well as expression of a very distinct set of genes, including genes encoding various members of the taste transduction machinery and pro-inflammatory cyclooxygenases. Initially discovered in rat trachea, tuft cells were gradually identified in various mucosal tissues, and later also in non-mucosal tissues, most recent of which is the thymus. Although tuft cells were discovered more than 60 years ago, their functions in the various tissues remained a mystery until recent years. Today, tuft cells are thought to function as sensors of various types of chemical signals, to which they respond by secretion of diverse biological mediators such as IL25 or acetylcholine. Intestinal tuft cells were also shown to mediate type 2 immunity against parasites. Here, we review the current knowledge on tuft cell characteristics, development and heterogeneity, discuss their potential functions and explore the possible implications and significance of their discovery in the thymus.
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Affiliation(s)
- Shir Nevo
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Noam Kadouri
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Jakub Abramson
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel.
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7
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Banerjee A, McKinley ET, von Moltke J, Coffey RJ, Lau KS. Interpreting heterogeneity in intestinal tuft cell structure and function. J Clin Invest 2018; 128:1711-1719. [PMID: 29714721 DOI: 10.1172/jci120330] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Intestinal tuft cells are a morphologically unique cell type, best characterized by striking microvilli that form an apical tuft. These cells represent approximately 0.5% of gut epithelial cells depending on location. While they are known to express chemosensory receptors, their function has remained unclear. Recently, numerous groups have revealed startling insights into intestinal tuft cell biology. Here, we review the latest developments in understanding this peculiar cell type's structure and function. Recent advances in volumetric microscopy have begun to elucidate tuft cell ultrastructure with respect to its cellular neighbors. Moreover, single-cell approaches have revealed greater diversity in the tuft cell population than previously appreciated and uncovered novel markers to characterize this heterogeneity. Finally, advanced model systems have revealed tuft cells' roles in mucosal healing and orchestrating type 2 immunity against eukaryotic infection. While much remains unknown about intestinal tuft cells, these critical advances have illuminated the physiological importance of these previously understudied cells and provided experimentally tractable tools to interrogate this rare cell population. Tuft cells act as luminal sensors, linking the luminal microbiome to the host immune system, which may make them a potent clinical target for modulating host response to a variety of acute or chronic immune-driven conditions.
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Affiliation(s)
- Amrita Banerjee
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Eliot T McKinley
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jakob von Moltke
- Department of Immunology, University of Washington, Seattle, Washington, USA
| | - Robert J Coffey
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Ken S Lau
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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8
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Mindt BC, Fritz JH, Duerr CU. Group 2 Innate Lymphoid Cells in Pulmonary Immunity and Tissue Homeostasis. Front Immunol 2018; 9:840. [PMID: 29760695 PMCID: PMC5937028 DOI: 10.3389/fimmu.2018.00840] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 04/05/2018] [Indexed: 12/21/2022] Open
Abstract
Group 2 innate lymphoid cells (ILC2) represent an evolutionary rather old but only recently identified member of the family of innate lymphoid cells and have received much attention since their detailed description in 2010. They can orchestrate innate as well as adaptive immune responses as they interact with and influence several immune and non-immune cell populations. Moreover, ILC2 are able to rapidly secrete large amounts of type 2 cytokines that can contribute to protective but also detrimental host immune responses depending on timing, location, and physiological context. Interestingly, ILC2, despite their scarcity, are the dominant innate lymphoid cell population in the lung, indicating a key role as first responders and amplifiers upon immune challenge at this site. In addition, the recently described tissue residency of ILC2 further underlines the importance of their respective microenvironment. In this review, we provide an overview of lung physiology including a description of the most prominent pulmonary resident cells together with a review of known and potential ILC2 interactions within this unique environment. We will further outline recent observations regarding pulmonary ILC2 during immune challenge including respiratory infections and discuss different models and approaches to study ILC2 biology in the lung.
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Affiliation(s)
- Barbara C Mindt
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada.,McGill University Research Centre on Complex Traits (MRCCT), McGill University, Montreal, QC, Canada.,FOCiS Centre of Excellence in Translational Immunology (CETI), McGill University, Montreal, QC, Canada
| | - Jörg H Fritz
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada.,McGill University Research Centre on Complex Traits (MRCCT), McGill University, Montreal, QC, Canada.,FOCiS Centre of Excellence in Translational Immunology (CETI), McGill University, Montreal, QC, Canada.,Department of Physiology, McGill University, Montreal, QC, Canada
| | - Claudia U Duerr
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada.,McGill University Research Centre on Complex Traits (MRCCT), McGill University, Montreal, QC, Canada.,FOCiS Centre of Excellence in Translational Immunology (CETI), McGill University, Montreal, QC, Canada.,Institute of Microbiology and Infection Immunology, Charité - University Medical Centre Berlin, Berlin, Germany
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9
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Goedicke-Fritz S, Härtel C, Krasteva-Christ G, Kopp MV, Meyer S, Zemlin M. Preterm Birth Affects the Risk of Developing Immune-Mediated Diseases. Front Immunol 2017; 8:1266. [PMID: 29062316 PMCID: PMC5640887 DOI: 10.3389/fimmu.2017.01266] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 09/22/2017] [Indexed: 12/12/2022] Open
Abstract
Prematurity affects approximately 10% of all children, resulting in drastically altered antigen exposure due to premature confrontation with microbes, nutritional antigens, and other environmental factors. During the last trimester of pregnancy, the fetal immune system adapts to tolerate maternal and self-antigens, while also preparing for postnatal immune defense by acquiring passive immunity from the mother. Since the perinatal period is regarded as the most important “window of opportunity” for imprinting metabolism and immunity, preterm birth may have long-term consequences for the development of immune-mediated diseases. Intriguingly, preterm neonates appear to develop bronchial asthma more frequently, but atopic dermatitis less frequently in comparison to term neonates. The longitudinal study of preterm neonates could offer important insights into the process of imprinting for immune-mediated diseases. On the one hand, preterm birth may interrupt influences of the intrauterine environment on the fetus that increase or decrease the risk of later immune disease (e.g., maternal antibodies and placenta-derived factors), whereas on the other hand, it may lead to the premature exposure to protective or harmful extrauterine factors such as microbiota and nutritional antigen. Solving this puzzle may help unravel new preventive and therapeutic approaches for immune diseases.
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Affiliation(s)
- Sybelle Goedicke-Fritz
- Laboratory of Neonatology and Pediatric Immunology, Department of Pediatrics, Philipps University Marburg, Marburg, Germany.,Department of General Pediatrics and Neonatology, Saarland University Medical School, Homburg, Germany
| | | | | | - Matthias V Kopp
- Department of Pediatric Allergy and Pulmonology, University of Lübeck, Airway Research-Center North (ARCN), Lübeck, Germany
| | - Sascha Meyer
- Department of General Pediatrics and Neonatology, Saarland University Medical School, Homburg, Germany
| | - Michael Zemlin
- Department of General Pediatrics and Neonatology, Saarland University Medical School, Homburg, Germany
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10
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11
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The intestinal epithelium tuft cells: specification and function. Cell Mol Life Sci 2012; 69:2907-17. [PMID: 22527717 PMCID: PMC3417095 DOI: 10.1007/s00018-012-0984-7] [Citation(s) in RCA: 181] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 03/21/2012] [Accepted: 03/26/2012] [Indexed: 02/08/2023]
Abstract
The intestinal epithelium, composed of at least seven differentiated cell types, represents an extraordinary model to understand the details of multi-lineage differentiation, a question that is highly relevant in developmental biology as well as for clinical applications. This review focuses on intestinal epithelial tuft cells that have been acknowledged as a separate entity for more than 60 years but whose function remains a mystery. We discuss what is currently known about the molecular basis of tuft cell fate and differentiation and why elucidating tuft cell function has been so difficult. Finally, we summarize the current hypotheses on their potential involvement in diseases of the gastro-intestinal tract.
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12
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Sbarbati A, Tizzano M, Merigo F, Benati D, Nicolato E, Boschi F, Cecchini MP, Scambi I, Osculati F. Acyl Homoserine Lactones Induce Early Response in the Airway. Anat Rec (Hoboken) 2009; 292:439-48. [DOI: 10.1002/ar.20866] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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14
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Morroni M, Cangiotti AM, Cinti S. Brush cells in the human duodenojejunal junction: an ultrastructural study. J Anat 2007; 211:125-31. [PMID: 17509089 PMCID: PMC2375792 DOI: 10.1111/j.1469-7580.2007.00738.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Brush cells have been identified in the respiratory and gastrointestinal tract mucosa of many mammalian species. In humans they are found in the respiratory tract and the gastrointestinal apparatus, in both the stomach and the gallbladder. The function of brush cells is unknown, and most morphological data have been obtained in rodents. To extend our knowledge of human brush cells, we performed an ultrastructural investigation of human small intestine brush cells. Six brush cells identified in five out of more than 300 small intestine biopsies performed for gastrointestinal tract disorders were examined by transmission electron microscopy. Five brush cells were located on the surface epithelium and one in a crypt. The five surface brush cells were characterized by a narrow apical pole from which emerged microvilli that were longer and thicker than those of enterocytes. The filamentous core extended far into the cell body without forming the terminal web. Caveolae were abundant. Filaments were in the form of microfilaments and intermediate filaments. Cytoplasmic projections containing filaments were found on the basolateral surface of brush cells. In a single cell, axons containing vesicles and dense core granules were in close contact both with the basal and the lateral surface of the cell. The crypt brush cell appeared less mature. We concluded that human small intestine brush cells share a similar ultrastructural biology with those of other mammals. They are polarized and well-differentiated cells endowed with a distinctive cytoskeleton. The observation of nerve fibres closely associated with brush cells, never previously described in humans, lends support to the hypothesis of a receptor role for these cells.
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Affiliation(s)
- Manrico Morroni
- Institute of Normal Human Morphology, School of Medicine, Polytechnic University of Marche, Ancona, Italy.
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15
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Abstract
Over the past 50 years, hundreds of studies have described those cells that are characterized by a brush of rigid apical microvilli with long rootlets, and which are found in the digestive and respiratory apparatuses. These cells have been given names such as brush cells, tuft cells, fibrillovesicular cells, multivesicular cells and caveolated cells. More recently, it has been realized that all these elements may represent a single cell type, probably with a chemosensory role, even if other functions (e.g. secretory or absorptive) seem to be possible. Very recent developments have permitted a partial definition of the chemical code characterizing these elements, revealing the presence of molecules involved in chemoreceptorial cell signalling. A molecular cascade, similar to those characterizing the gustatory epithelium, seems to be present in these elements. These new data suggest that these elements can be considered solitary chemosensory cells with the presence of the apical 'brush' as an inconsistent feature. They seem to comprise a diffuse chemosensory system that covers large areas (probably the whole digestive and respiratory apparatuses) with analogies to chemosensory systems described in aquatic vertebrates.
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Affiliation(s)
- A Sbarbati
- Department of Morphological-Biomedical Sciences, Section of Anatomy and Histology, University of Verona, Italy.
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16
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Reid L, Meyrick B, Antony VB, Chang LY, Crapo JD, Reynolds HY. The mysterious pulmonary brush cell: a cell in search of a function. Am J Respir Crit Care Med 2005; 172:136-9. [PMID: 15817800 PMCID: PMC2718446 DOI: 10.1164/rccm.200502-203ws] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Brush cells, also termed tuft, caveolated, multivesicular, and fibrillovesicular cells, are part of the epithelial layer in the gastrointestinal and respiratory tracts. The cells are characterized by the presence of a tuft of blunt, squat microvilli (approximately 120-140/cell) on the cell surface. The microvilli contain filaments that stretch into the underlying cytoplasm. They have a distinctive pear shape with a wide base and a narrow microvillous apex. The function of the pulmonary brush cell is obscure. For this reason, a working group convened on August 23, 2004, in Bethesda, Maryland, to review the physiologic role of the brush (microvillous) cell in normal airways and alveoli and in respiratory diseases involving the alveolar region (e.g., emphysema and fibrosis) and airway disease characterized by either excessive or insufficient amounts of airway fluid (e.g., cystic fibrosis, chronic bronchitis, and exercise-induced asthma). The group formulated several suggestions for future investigation. For example, it would be useful to have a panel of specific markers for the brush cell and in this way separate these cells for culture and more direct examination of their function (e.g., microarray analysis and proteomics). Using quantitative analysis, it was suggested to examine the number and location of the cells in disease models. Understanding the function of these cells in alveoli and airways may provide clues to the pathogenesis of several disease states (e.g., cystic fibrosis and fibrosis) as well as a key for new therapeutic modalities.
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Affiliation(s)
- Lynne Reid
- Division of Lung Diseases, National Heart, Lung, and Blood Institute/NIH, Two Rockledge Center, 67-1 Rockledge Drive, Bethesda, MD 20892-7952, USA
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17
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Abstract
We performed a morphologic examination of human fetal lung tissue, using scanning and transmission electron microscopy, in order to establish the presence of brush cells in extrapulmonary and intrapulmonary airways, and developing acinar epithelium. Brush cells, characterized by a border of regular straight microvilli containing a filamentous core, were observed within the tracheal epithelium of a 19-20 week gestational age fetus. These cells constituted 0.5% of the total epithelial cell population. Brush cells were not seen within the bronchial, bronchiolar or developing acinar epithelium. Our study shows that brush cells occur infrequently but normally in the developing tracheal epithelium of the second trimester fetus.
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Affiliation(s)
- M F DiMaio
- Jack and Lucy Clark Department of Pediatrics, Mount Sinai School of Medicine, New York, New York
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18
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Rowley JC, Moran DT, Jafek BW. Peroxidase backfills suggest the mammalian olfactory epithelium contains a second morphologically distinct class of bipolar sensory neuron: the microvillar cell. Brain Res 1989; 502:387-400. [PMID: 2819473 DOI: 10.1016/0006-8993(89)90635-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The olfactory epithelium of man, rat and some other mammals consists of 4 cell types: ciliated olfactory receptors, microvillar cells, supporting (sustentacular) cells, and basal cells. Of these, the microvillar cell is least well understood: its function is unknown. In this study, a hypothesis is put forth: that the microvillar cells in the mammalian olfactory epithelium comprise a morphologically distinct class of sensory receptor. The hypothesis is tested by injecting the cytochemical tracer macromolecule horseradish peroxidase (HRP) into the olfactory bulb of the rat, and observing its pattern of uptake in the olfactory epithelium by light and electron microscopy. In these experiments, ciliated olfactory receptors and microvillar cells backfilled with HRP: supporting and basal cells did not. The data, which support the hypothesis, indicate the microvillar cells, along with the ciliated olfactory receptors, send axons to the olfactory bulb. Consequently, it is concluded that the microvillar cell is a sensory bipolar neuron, with the cell body in the olfactory epithelium, that sends a dendrite to the site of stimulus reception at the free surface of the olfactory epithelium, and an axon to the olfactory bulb in the brain. The similarity of microvillar cells in the olfactory epithelium to 'brush cells' found throughout the respiratory tract is discussed in detail.
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Affiliation(s)
- J C Rowley
- Department of Cellular and Structural Biology, University of Colorado School of Medicine, Denver 80262
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19
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Allen JL. Relative contributions of the rib cage and abdomen during augmented breaths. Pediatr Pulmonol 1988; 5:268-9. [PMID: 2976930 DOI: 10.1002/ppul.1950050416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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