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Wilson CE, Lasher RS, Salcedo E, Yang R, Dzowo Y, Kinnamon JC, Finger TE. Death in the taste bud: Morphological features of dying taste cells and engulfment by Type I cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.06.611711. [PMID: 39314340 PMCID: PMC11418956 DOI: 10.1101/2024.09.06.611711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
Abstract
Taste buds comprise 50-100 epithelial derived cells, which are renewed throughout the life of an organism. Immature cells enter the bud at its base, maturing into one of three distinct cell types. How taste cells die and/or exit the bud, however, remains unclear. Here we present morphological data obtained through Serial Blockface Scanning Electron Microscopy of murine circumvallate taste buds, revealing several taste cells at the end of their life (4-6 per bud). Cells we identify as dying share certain morphological features typical of apoptosis: swollen endoplasmic reticulum, large lysosomes, degrading organelles, distended outer nuclear membranes, heterochromatin reorganization, cell shrinkage, and cell and/or nuclear fragmentation. Based on these features, we divide the cells into "early" and "late" stage dying cells. Most early stage dying cells have Type II cell morphologies, while a few display Type III cell features. Many dying cells maintain contacts with nerve fibers, but those fibers often appear detached from the main trunk of an afferent nerve fiber. Dying cells, like mature Type II and Type III taste cells, are surrounded by Type I taste cells, the glial-like cells of the bud. In many instances Type I cells appear to be engulfing their dying neighbors, suggesting a novel, phagocytic role for Type I cells. Surprisingly, virtually no Type I cells, which have the shortest residence time in taste buds, display features of apoptosis. The ultimate fate of Type I cells therefore remains enigmatic.
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Affiliation(s)
- Courtney E Wilson
- Rocky Mountain Taste & Smell Center, University of Colorado School of Medicine, CU Anschutz Medical Campus, Aurora, CO 80045
| | - Robert S Lasher
- Rocky Mountain Taste & Smell Center, University of Colorado School of Medicine, CU Anschutz Medical Campus, Aurora, CO 80045
| | - Ernesto Salcedo
- Rocky Mountain Taste & Smell Center, University of Colorado School of Medicine, CU Anschutz Medical Campus, Aurora, CO 80045
| | - Ruibiao Yang
- Rocky Mountain Taste & Smell Center, University of Colorado School of Medicine, CU Anschutz Medical Campus, Aurora, CO 80045
| | - Yannick Dzowo
- Rocky Mountain Taste & Smell Center, University of Colorado School of Medicine, CU Anschutz Medical Campus, Aurora, CO 80045
| | - John C Kinnamon
- Rocky Mountain Taste & Smell Center, University of Colorado School of Medicine, CU Anschutz Medical Campus, Aurora, CO 80045
| | - Thomas E Finger
- Rocky Mountain Taste & Smell Center, University of Colorado School of Medicine, CU Anschutz Medical Campus, Aurora, CO 80045
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Dietz A, Senf K, Neuhaus EM. ACKR3 in olfactory glia cells shapes the immune defense of the olfactory mucosa. Glia 2024; 72:1183-1200. [PMID: 38477581 DOI: 10.1002/glia.24527] [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: 01/09/2024] [Revised: 03/04/2024] [Accepted: 03/06/2024] [Indexed: 03/14/2024]
Abstract
Barrier-forming olfactory glia cells, termed sustentacular cells, play important roles for immune defense of the olfactory mucosa, for example as entry sites for SARS-CoV-2 and subsequent development of inflammation-induced smell loss. Here we demonstrate that sustentacular cells express ACKR3, a chemokine receptor that functions both as a scavenger of the chemokine CXCL12 and as an activator of alternative signaling pathways. Differential gene expression analysis of bulk RNA sequencing data obtained from WT and ACKR3 conditional knockout mice revealed upregulation of genes involved in immune defense. To map the regulated genes to the different cell types of the olfactory mucosa, we employed biocomputational methods utilizing a single-cell reference atlas. Transcriptome analysis, PCR and immunofluorescence identified up-regulation of NF-κB-related genes, known to amplify inflammatory signaling and to facilitate leukocyte transmigration, in the gliogenic lineage. Accordingly, we found a marked increase in leukocyte-expressed genes and confirmed leukocyte infiltration into the olfactory mucosa. In addition, lack of ACKR3 led to enhanced expression and secretion of early mediators of immune defense by Bowman's glands. As a result, the number of apoptotic cells in the epithelium was decreased. In conclusion, our research underlines the importance of sustentacular cells in immune defense of the olfactory mucosa. Moreover, it identifies ACKR3, a druggable G protein-coupled receptor, as a promising target for modulation of inflammation-associated anosmia.
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Affiliation(s)
- André Dietz
- Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Katja Senf
- Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Eva M Neuhaus
- Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
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Wellford SA, Moseman EA. Olfactory immunology: the missing piece in airway and CNS defence. Nat Rev Immunol 2024; 24:381-398. [PMID: 38097777 PMCID: PMC11560121 DOI: 10.1038/s41577-023-00972-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2023] [Indexed: 12/23/2023]
Abstract
The olfactory mucosa is a component of the nasal airway that mediates the sense of smell. Recent studies point to an important role for the olfactory mucosa as a barrier to both respiratory pathogens and to neuroinvasive pathogens that hijack the olfactory nerve and invade the CNS. In particular, the COVID-19 pandemic has demonstrated that the olfactory mucosa is an integral part of a heterogeneous nasal mucosal barrier critical to upper airway immunity. However, our insufficient knowledge of olfactory mucosal immunity hinders attempts to protect this tissue from infection and other diseases. This Review summarizes the state of olfactory immunology by highlighting the unique immunologically relevant anatomy of the olfactory mucosa, describing what is known of olfactory immune cells, and considering the impact of common infectious diseases and inflammatory disorders at this site. We will offer our perspective on the future of the field and the many unresolved questions pertaining to olfactory immunity.
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Affiliation(s)
- Sebastian A Wellford
- Department of Integrative Immunobiology, Duke University School of Medicine, Durham, NC, USA
| | - E Ashley Moseman
- Department of Integrative Immunobiology, Duke University School of Medicine, Durham, NC, USA.
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Marin C, Alobid I, López-Chacón M, VanStrahlen CR, Mullol J. Type 2 and Non-type 2 Inflammation in the Upper Airways: Cellular and Molecular Alterations in Olfactory Neuroepithelium Cell Populations. Curr Allergy Asthma Rep 2024; 24:211-219. [PMID: 38492160 PMCID: PMC11008081 DOI: 10.1007/s11882-024-01137-x] [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] [Accepted: 02/15/2024] [Indexed: 03/18/2024]
Abstract
PURPOSE OF REVIEW Neurogenesis occurring in the olfactory epithelium is critical to continuously replace olfactory neurons to maintain olfactory function, but is impaired during chronic type 2 and non-type 2 inflammation of the upper airways. In this review, we describe the neurobiology of olfaction and the olfactory alterations in chronic rhinosinusitis with nasal polyps (type 2 inflammation) and post-viral acute rhinosinusitis (non-type 2 inflammation), highlighting the role of immune response attenuating olfactory neurogenesis as a possibly mechanism for the loss of smell in these diseases. RECENT FINDINGS Several studies have provided relevant insights into the role of basal stem cells as direct participants in the progression of chronic inflammation identifying a functional switch away from a neuro-regenerative phenotype to one contributing to immune defense, a process that induces a deficient replacement of olfactory neurons. The interaction between olfactory stem cells and immune system might critically underlie ongoing loss of smell in type 2 and non-type 2 inflammatory upper airway diseases. In this review, we describe the neurobiology of olfaction and the olfactory alterations in type 2 and non-type 2 inflammatory upper airway diseases, highlighting the role of immune response attenuating olfactory neurogenesis, as a possibly mechanism for the lack of loss of smell recovery.
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Affiliation(s)
- Concepció Marin
- INGENIO, IRCE, Fundació Recerca Clínic Barcelona-Institut d'Investigacions Biomèdiques August Pi i Sunyer (FRCB-IDIBAPS), Barcelona, Catalonia, Spain.
- Centre for Biomedical Research in Respiratory Diseases (CIBERES), Health Institute Carlos III, Madrid, Spain.
| | - Isam Alobid
- INGENIO, IRCE, Fundació Recerca Clínic Barcelona-Institut d'Investigacions Biomèdiques August Pi i Sunyer (FRCB-IDIBAPS), Barcelona, Catalonia, Spain
- Centre for Biomedical Research in Respiratory Diseases (CIBERES), Health Institute Carlos III, Madrid, Spain
- Rhinology Unit and Smell Clinic, ENT Department, Hospital Clínic, Barcelona, Catalonia, Spain
- Universitat de Barcelona, Barcelona, Spain
| | - Mauricio López-Chacón
- INGENIO, IRCE, Fundació Recerca Clínic Barcelona-Institut d'Investigacions Biomèdiques August Pi i Sunyer (FRCB-IDIBAPS), Barcelona, Catalonia, Spain
- Centre for Biomedical Research in Respiratory Diseases (CIBERES), Health Institute Carlos III, Madrid, Spain
- Rhinology Unit and Smell Clinic, ENT Department, Hospital Clínic, Barcelona, Catalonia, Spain
| | - Camilo R VanStrahlen
- INGENIO, IRCE, Fundació Recerca Clínic Barcelona-Institut d'Investigacions Biomèdiques August Pi i Sunyer (FRCB-IDIBAPS), Barcelona, Catalonia, Spain
- Centre for Biomedical Research in Respiratory Diseases (CIBERES), Health Institute Carlos III, Madrid, Spain
- Rhinology Unit and Smell Clinic, ENT Department, Hospital Clínic, Barcelona, Catalonia, Spain
| | - Joaquim Mullol
- INGENIO, IRCE, Fundació Recerca Clínic Barcelona-Institut d'Investigacions Biomèdiques August Pi i Sunyer (FRCB-IDIBAPS), Barcelona, Catalonia, Spain.
- Centre for Biomedical Research in Respiratory Diseases (CIBERES), Health Institute Carlos III, Madrid, Spain.
- Rhinology Unit and Smell Clinic, ENT Department, Hospital Clínic, Barcelona, Catalonia, Spain.
- Universitat de Barcelona, Barcelona, Spain.
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Landon SM, Baker K, Macpherson LJ. Give-and-take of gustation: the interplay between gustatory neurons and taste buds. Chem Senses 2024; 49:bjae029. [PMID: 39078723 PMCID: PMC11315769 DOI: 10.1093/chemse/bjae029] [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] [Indexed: 08/11/2024] Open
Abstract
Mammalian taste buds are highly regenerative and can restore themselves after normal wear and tear of the lingual epithelium or following physical and chemical insults, including burns, chemotherapy, and nerve injury. This is due to the continual proliferation, differentiation, and maturation of taste progenitor cells, which then must reconnect with peripheral gustatory neurons to relay taste signals to the brain. The turnover and re-establishment of peripheral taste synapses are vital to maintain this complex sensory system. Over the past several decades, the signal transduction and neurotransmitter release mechanisms within taste cells have been well delineated. However, the complex dynamics between synaptic partners in the tongue (taste cell and gustatory neuron) are only partially understood. In this review, we highlight recent findings that have improved our understanding of the mechanisms governing connectivity and signaling within the taste bud and the still-unresolved questions regarding the complex interactions between taste cells and gustatory neurons.
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Affiliation(s)
- Shannon M Landon
- Department of Neuroscience, Developmental and Regenerative Biology, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, United States
| | - Kimberly Baker
- Department of Neuroscience, Developmental and Regenerative Biology, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, United States
- 59th Medical Wing: Surgical and Technological Advancements for Traumatic Injuries in Combat: 204 Wagner Ave, San Antonio, TX 78211, United States
| | - Lindsey J Macpherson
- Department of Neuroscience, Developmental and Regenerative Biology, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, United States
- Brain Health Consortium, The University of Texas at San Antonio, San Antonio, TX, United States
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Dong G, Boothe K, He L, Shi Y, McCluskey LP. Altered peripheral taste function in a mouse model of inflammatory bowel disease. Sci Rep 2023; 13:18895. [PMID: 37919307 PMCID: PMC10622515 DOI: 10.1038/s41598-023-46244-3] [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: 08/28/2023] [Accepted: 10/30/2023] [Indexed: 11/04/2023] Open
Abstract
Increased sugar intake and taste dysfunction have been reported in patients with inflammatory bowel disease (IBD), a chronic disorder characterized by diarrhea, pain, weight loss and fatigue. It was previously unknown whether taste function changes in mouse models of IBD. Mice consumed dextran sodium sulfate (DSS) during three 7-day cycles to induce chronic colitis. DSS-treated mice displayed signs of disease, including significant weight loss, diarrhea, loss of colon architecture, and inflammation of the colon. After the last DSS cycle we assessed taste function by recording electrophysiological responses from the chorda tympani (CT) nerve, which transmits activity from lingual taste buds to the brain. DSS treatment significantly reduced neural taste responses to natural and artificial sweeteners. Responses to carbohydrate, salt, sour or bitter tastants were unaffected in mice with colitis, but umami responses were modestly elevated. DSS treatment modulated the expression of receptor subunits that transduce sweet and umami stimuli in oral taste buds as a substrate for functional changes. Dysregulated systemic cytokine responses or dysbiosis that occurs during chronic colitis may be upstream from changes in oral taste buds. We demonstrate for the first time that colitis alters taste input to the brain, which could exacerbate malnutrition in IBD patients.
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Affiliation(s)
- Guangkuo Dong
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, 1120 15th Street/CA-3016, Augusta, GA, 30912, USA
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Khaylie Boothe
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, 1120 15th Street/CA-3016, Augusta, GA, 30912, USA
| | - Lianying He
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, 1120 15th Street/CA-3016, Augusta, GA, 30912, USA
| | - Yang Shi
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, 1120 15th Street/CA-3016, Augusta, GA, 30912, USA
- Division of Biostatistics and Data Science, Department of Population Health Sciences, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Lynnette Phillips McCluskey
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, 1120 15th Street/CA-3016, Augusta, GA, 30912, USA.
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Dong G, Boothe K, He L, Shi Y, McCluskey LP. Altered peripheral taste function in a mouse model of inflammatory bowel disease. RESEARCH SQUARE 2023:rs.3.rs-3304297. [PMID: 37720020 PMCID: PMC10503843 DOI: 10.21203/rs.3.rs-3304297/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Increased sugar intake and taste dysfunction have been reported in patients with inflammatory bowel disease (IBD), a chronic disorder characterized by diarrhea, pain, weight loss and fatigue. It was previously unknown whether taste function changes in mouse models of IBD. Mice consumed dextran sodium sulfate (DSS) during three 7-day cycles to induce chronic colitis. DSS-treated mice displayed signs of disease, including significant weight loss, diarrhea, loss of colon architecture, and inflammation of the colon. After the last DSS cycle we assessed taste function by recording electrophysiological responses from the chorda tympani (CT) nerve, which transmits activity from lingual taste buds to the brain. DSS treatment significantly reduced neural taste responses to natural and artificial sweeteners. Responses to carbohydrate, salt, sour or bitter tastants were unaffected in mice with colitis, but umami responses were modestly elevated. DSS treatment modulated the expression of receptor subunits that transduce sweet and umami stimuli in oral taste buds as a substrate for functional changes. Dysregulated systemic cytokine responses, or dysbiosis that occurs during chronic colitis may be upstream from changes in oral taste buds. We demonstrate for the first time that colitis alters taste input to the brain, which could exacerbate malnutrition in IBD patients.
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