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Stark R. The olfactory bulb: A neuroendocrine spotlight on feeding and metabolism. J Neuroendocrinol 2024; 36:e13382. [PMID: 38468186 DOI: 10.1111/jne.13382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 02/22/2024] [Accepted: 02/25/2024] [Indexed: 03/13/2024]
Abstract
Olfaction is the most ancient sense and is needed for food-seeking, danger protection, mating and survival. It is often the first sensory modality to perceive changes in the external environment, before sight, taste or sound. Odour molecules activate olfactory sensory neurons that reside on the olfactory epithelium in the nasal cavity, which transmits this odour-specific information to the olfactory bulb (OB), where it is relayed to higher brain regions involved in olfactory perception and behaviour. Besides odour processing, recent studies suggest that the OB extends its function into the regulation of food intake and energy balance. Furthermore, numerous hormone receptors associated with appetite and metabolism are expressed within the OB, suggesting a neuroendocrine role outside the hypothalamus. Olfactory cues are important to promote food preparatory behaviours and consumption, such as enhancing appetite and salivation. In addition, altered metabolism or energy state (fasting, satiety and overnutrition) can change olfactory processing and perception. Similarly, various animal models and human pathologies indicate a strong link between olfactory impairment and metabolic dysfunction. Therefore, understanding the nature of this reciprocal relationship is critical to understand how olfactory or metabolic disorders arise. This present review elaborates on the connection between olfaction, feeding behaviour and metabolism and will shed light on the neuroendocrine role of the OB as an interface between the external and internal environments. Elucidating the specific mechanisms by which olfactory signals are integrated and translated into metabolic responses holds promise for the development of targeted therapeutic strategies and interventions aimed at modulating appetite and promoting metabolic health.
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Affiliation(s)
- Romana Stark
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, Australia
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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 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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Wellford SA, Moseman EA. Olfactory immune response to SARS-CoV-2. Cell Mol Immunol 2024; 21:134-143. [PMID: 38143247 PMCID: PMC10806031 DOI: 10.1038/s41423-023-01119-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 12/04/2023] [Indexed: 12/26/2023] Open
Abstract
Numerous pathogens can infect the olfactory tract, yet the pandemic caused by SARS-CoV-2 has strongly emphasized the importance of the olfactory mucosa as an immune barrier. Situated in the nasal passages, the olfactory mucosa is directly exposed to the environment to sense airborne odorants; however, this also means it can serve as a direct route of entry from the outside world into the brain. As a result, olfactotropic infections can have serious consequences, including dysfunction of the olfactory system, CNS invasion, dissemination to the lower respiratory tract, and transmission between individuals. Recent research has shown that a distinctive immune response is needed to protect this neuronal and mucosal tissue. A better understanding of innate, adaptive, and structural immune barriers in the olfactory mucosa is needed to develop effective therapeutics and vaccines against olfactotropic microbes such as SARS-CoV-2. Here, we summarize the ramifications of SARS-CoV-2 infection of the olfactory mucosa, review the subsequent immune response, and discuss important areas of future research for olfactory immunity to infectious disease.
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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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Kılıçarslan O, Çebi AY, Uçar D. Retinal nerve fiber layer thickness and peripapillary vasculature of post-COVID-19 patients with and without olfactory/gustatory dysfunction symptoms. Taiwan J Ophthalmol 2024; 14:102-107. [PMID: 38654983 PMCID: PMC11034685 DOI: 10.4103/tjo.tjo-d-22-00065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 12/06/2022] [Indexed: 04/26/2024] Open
Abstract
PURPOSE We aimed to compare retinal nerve fiber layer (RNFL) thickness and peripapillary vessel density values between COVID-19 patients with or without olfactory/gustatory dysfunction symptoms and healthy controls. MATERIALS AND METHODS We evaluated RNFL and radial peripapillary capillary vessel density (RPC-VD) values of 41 patients who had COVID-19 history and age- and gender-matched control group including 31 healthy individuals with optical coherence tomography angiography. First, post-COVID-19 group's and control group's RNFL and RPC-VD values were compared, then post-COVID-19 patients were divided into subgroups according to the presence (subgroup-A) and absence (subgroup-B) of olfactory/gustatory dysfunction symptoms, and same parameters were analyzed for subgroups. RESULTS Forty-one eyes of 41 post-COVID-19 patients and 31 eyes of 31 age- and gender-matched healthy controls were included in this cross-sectional study. In RNFL analysis, inferior sector thickness was found significantly lower in post-COVID-19 patients by comparison with control group (P = 0.041). In subgroup analyses, COVID-19 patients who first presented with olfactory/gustatory dysfunction symptoms had higher peripapillary and whole image optic disc capillary density (P = 0.011 and P = 0.002) compared to those who had not had these symptoms. CONCLUSION Lower RPC-VD and RNFL thickness were detected in COVID-19 patients compared to healthy controls. Higher Disc-VD values were found in COVID-19 patients with chemosensorial dysfunction (CSD) symptoms compared to those who had not had these symptoms probably due to milder disease course in COVID-19 with CSD. Sectorial RNFL attenuation in COVID-19 might have occurred secondary to peripapillary capillary circulation defect.
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Affiliation(s)
| | | | - Didar Uçar
- Department of Ophthalmology, Istanbul University-Cerrahpasa, Cerrahpasa Medical Faculty, Istanbul, Turkey
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Zedan A, Winters AD, Yu W, Wang S, Ren Y, Takeshita A, Gong Q. Antiviral Functions of Type I and Type III Interferons in the Olfactory Epithelium. Biomolecules 2023; 13:1762. [PMID: 38136633 PMCID: PMC10741941 DOI: 10.3390/biom13121762] [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: 11/01/2023] [Revised: 12/04/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023] Open
Abstract
The olfactory neuroepithelium (OE) is one of the few neuronal tissues where environmental pathogens can gain direct access. Despite this vulnerable arrangement, little is known about the protective mechanisms in the OE to prevent viral infection and its antiviral responses. We systematically investigated acute responses in the olfactory mucosa upon exposure to vesicular stomatitis virus (VSV) via RNA-seq. VSVs were nasally inoculated into C57BL/6 mice. Olfactory mucosae were dissected for gene expression analysis at different time points after viral inoculation. Interferon functions were determined by comparing the viral load in interferon receptor knockout (Ifnar1-/- and Ifnlr1-/-) with wildtype OE. Antiviral responses were observed as early as 24 h after viral exposure in the olfactory mucosa. The rapidly upregulated transcripts observed included specific type I as well as type III interferons (Ifn) and interferon-stimulated genes. Genetic analyses demonstrated that both type I and type III IFN signaling are required for the suppression of viral replication in the olfactory mucosa. Exogenous IFN application effectively blocks viral replication in the OE. These findings reveal that the OE possesses an innate ability to suppress viral infection. Type I and type III IFNs have prominent roles in OE antiviral functions.
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Affiliation(s)
- Ahmad Zedan
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA 95616, USA; (A.Z.); (A.D.W.); (A.T.)
| | - Ashley D. Winters
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA 95616, USA; (A.Z.); (A.D.W.); (A.T.)
| | - Wei Yu
- Department of Physiology, Xi’an Medical University, Xi’an 710021, China;
| | - Shuangyan Wang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Qingdao University, Qingdao 266071, China;
| | - Ying Ren
- Department of Stomatology, Zhongshan Hospital, Fudan University, Shanghai 200032, China;
| | - Ashley Takeshita
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA 95616, USA; (A.Z.); (A.D.W.); (A.T.)
| | - Qizhi Gong
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA 95616, USA; (A.Z.); (A.D.W.); (A.T.)
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6
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Habif JC, Xie C, de Celis C, Ukhanov K, Green WW, Moretta JC, Zhang L, Campbell RJ, Martens JR. The role of a ciliary GTPase in the regulation of neuronal maturation of olfactory sensory neurons. Development 2023; 150:286702. [PMID: 36661357 PMCID: PMC10110495 DOI: 10.1242/dev.201116] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 12/19/2022] [Indexed: 01/20/2023]
Abstract
Olfactory sensory neurons (OSNs) form embryonically and mature perinatally, innervating glomeruli and extending dendrites with multiple cilia. This process and its timing are crucial for odor detection and perception and continues throughout life. In the olfactory epithelium (OE), differentiated OSNs proceed from an immature (iOSN) to a mature (mOSN) state through well-defined sequential morphological and molecular transitions, but the precise mechanisms controlling OSN maturation remain largely unknown. We have identified that a GTPase, ARL13B, has a transient and maturation state-dependent expression in OSNs marking the emergence of a primary cilium. Utilizing an iOSN-specific Arl13b-null murine model, we examined the role of ARL13B in the maturation of OSNs. The loss of Arl13b in iOSNs caused a profound dysregulation of the cellular homeostasis and development of the OE. Importantly, Arl13b null OSNs demonstrated a delay in the timing of their maturation. Finally, the loss of Arl13b resulted in severe deformation in the structure and innervation of glomeruli. Our findings demonstrate a previously unknown role of ARL13B in the maturation of OSNs and development of the OE.
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Affiliation(s)
- Julien C Habif
- Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, FL 32610, USA
- University of Florida Center for Smell and Taste, Gainesville, FL 32610, USA
| | - Chao Xie
- Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, FL 32610, USA
- University of Florida Center for Smell and Taste, Gainesville, FL 32610, USA
| | - Carlos de Celis
- Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, FL 32610, USA
- University of Florida Center for Smell and Taste, Gainesville, FL 32610, USA
| | - Kirill Ukhanov
- Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, FL 32610, USA
- University of Florida Center for Smell and Taste, Gainesville, FL 32610, USA
| | - Warren W Green
- Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, FL 32610, USA
- University of Florida Center for Smell and Taste, Gainesville, FL 32610, USA
| | - Jordan C Moretta
- Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, FL 32610, USA
- University of Florida Center for Smell and Taste, Gainesville, FL 32610, USA
| | - Lian Zhang
- Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, FL 32610, USA
- University of Florida Center for Smell and Taste, Gainesville, FL 32610, USA
| | - Robert J Campbell
- Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, FL 32610, USA
- University of Florida Center for Smell and Taste, Gainesville, FL 32610, USA
| | - Jeffrey R Martens
- Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, FL 32610, USA
- University of Florida Center for Smell and Taste, Gainesville, FL 32610, USA
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7
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Patel ZM, Holbrook EH, Turner JH, Adappa ND, Albers MW, Altundag A, Appenzeller S, Costanzo RM, Croy I, Davis GE, Dehgani-Mobaraki P, Doty RL, Duffy VB, Goldstein BJ, Gudis DA, Haehner A, Higgins TS, Hopkins C, Huart C, Hummel T, Jitaroon K, Kern RC, Khanwalkar AR, Kobayashi M, Kondo K, Lane AP, Lechner M, Leopold DA, Levy JM, Marmura MJ, Mclelland L, Miwa T, Moberg PJ, Mueller CA, Nigwekar SU, O'Brien EK, Paunescu TG, Pellegrino R, Philpott C, Pinto JM, Reiter ER, Roalf DR, Rowan NR, Schlosser RJ, Schwob J, Seiden AM, Smith TL, Soler ZM, Sowerby L, Tan BK, Thamboo A, Wrobel B, Yan CH. International consensus statement on allergy and rhinology: Olfaction. Int Forum Allergy Rhinol 2022; 12:327-680. [PMID: 35373533 DOI: 10.1002/alr.22929] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 01/01/2021] [Accepted: 11/19/2021] [Indexed: 12/11/2022]
Abstract
BACKGROUND The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O). METHODS Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus. RESULTS The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies. CONCLUSION This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.
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Affiliation(s)
- Zara M Patel
- Otolaryngology, Stanford University School of Medicine, Stanford, California, USA
| | - Eric H Holbrook
- Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA
| | - Justin H Turner
- Otolaryngology, Vanderbilt School of Medicine, Nashville, Tennessee, USA
| | - Nithin D Adappa
- Otolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Mark W Albers
- Neurology, Harvard Medical School, Boston, Massachusetts, USA
| | - Aytug Altundag
- Otolaryngology, Biruni University School of Medicine, İstanbul, Turkey
| | - Simone Appenzeller
- Rheumatology, School of Medical Sciences, University of Campinas, São Paulo, Brazil
| | - Richard M Costanzo
- Physiology and Biophysics and Otolaryngology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Ilona Croy
- Psychology and Psychosomatic Medicine, TU Dresden, Dresden, Germany
| | - Greg E Davis
- Otolaryngology, Proliance Surgeons, Seattle and Puyallup, Washington, USA
| | - Puya Dehgani-Mobaraki
- Associazione Naso Sano, Umbria Regional Registry of Volunteer Activities, Corciano, Italy
| | - Richard L Doty
- Smell and Taste Center, Otolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Valerie B Duffy
- Allied Health Sciences, University of Connecticut, Storrs, Connecticut, USA
| | | | - David A Gudis
- Otolaryngology, Columbia University Irving Medical Center, New York, USA
| | - Antje Haehner
- Smell and Taste, Otolaryngology, TU Dresden, Dresden, Germany
| | - Thomas S Higgins
- Otolaryngology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Claire Hopkins
- Otolaryngology, Guy's and St. Thomas' Hospitals, London Bridge Hospital, London, UK
| | - Caroline Huart
- Otorhinolaryngology, Cliniques universitaires Saint-Luc, Institute of Neuroscience, Université catholgique de Louvain, Brussels, Belgium
| | - Thomas Hummel
- Smell and Taste, Otolaryngology, TU Dresden, Dresden, Germany
| | | | - Robert C Kern
- Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Ashoke R Khanwalkar
- Otolaryngology, Stanford University School of Medicine, Stanford, California, USA
| | - Masayoshi Kobayashi
- Otorhinolaryngology-Head and Neck Surgery, Mie University Graduate School of Medicine, Mie, Japan
| | - Kenji Kondo
- Otolaryngology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Andrew P Lane
- Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Matt Lechner
- Otolaryngology, Barts Health and University College London, London, UK
| | - Donald A Leopold
- Otolaryngology, University of Vermont Medical Center, Burlington, Vermont, USA
| | - Joshua M Levy
- Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Michael J Marmura
- Neurology Thomas Jefferson University School of Medicine, Philadelphia, Pennsylvania, USA
| | - Lisha Mclelland
- Otolaryngology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Takaki Miwa
- Otolaryngology, Kanazawa Medical University, Ishikawa, Japan
| | - Paul J Moberg
- Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | | | - Sagar U Nigwekar
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Erin K O'Brien
- Otolaryngology, Mayo Clinic Rochester, Rochester, Minnesota, USA
| | - Teodor G Paunescu
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | | | - Carl Philpott
- Otolaryngology, University of East Anglia, Norwich, UK
| | - Jayant M Pinto
- Otolaryngology, University of Chicago, Chicago, Illinois, USA
| | - Evan R Reiter
- Otolaryngology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - David R Roalf
- Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Nicholas R Rowan
- Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Rodney J Schlosser
- Otolaryngology, Medical University of South Carolina, Mt Pleasant, South Carolina, USA
| | - James Schwob
- Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Allen M Seiden
- Otolaryngology, University of Cincinnati School of Medicine, Cincinnati, Ohio, USA
| | - Timothy L Smith
- Otolaryngology, Oregon Health and Sciences University, Portland, Oregon, USA
| | - Zachary M Soler
- Otolaryngology, Medical University of South Carolina, Mt Pleasant, South Carolina, USA
| | - Leigh Sowerby
- Otolaryngology, University of Western Ontario, London, Ontario, Canada
| | - Bruce K Tan
- Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Andrew Thamboo
- Otolaryngology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Bozena Wrobel
- Otolaryngology, Keck School of Medicine, USC, Los Angeles, California, USA
| | - Carol H Yan
- Otolaryngology, School of Medicine, UCSD, La Jolla, California, USA
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Abstract
PURPOSE OF REVIEW Over the course of the coronavirus disease (COVID-19) pandemic, it has become increasingly clear that there is a high prevalence of neurological complications in people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). RECENT FINDINGS Studies of central nervous system (CNS) tissue in brain model systems and from adults with acute SARS-CoV-2 infection have begun to uncover potential mechanisms for neurological damage during COVID-19. These studies suggest that direct viral invasion of the CNS occurs in a subset of cases but does not frequently cause overt viral meningoencephalitis. Vascular abnormalities including microvascular thrombi and endothelial activation, as well as parainfectious processes, including CNS specific immune responses, may contribute to neurological symptoms during acute SARS-CoV-2 infection. SUMMARY Neuroimmune perturbations and vascular inflammation observed in people with COVID-19 may warrant investigation of immune-modulating interventions to ameliorate neurological complications associated with acute SARS-CoV-2 infection. These therapies may also impact the trajectory of potential long-term complications of COVID-19.
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Lee JC, Nallani R, Cass L, Bhalla V, Chiu AG, Villwock JA. A Systematic Review of the Neuropathologic Findings of Post-Viral Olfactory Dysfunction: Implications and Novel Insight for the COVID-19 Pandemic. Am J Rhinol Allergy 2021; 35:323-333. [PMID: 32915650 PMCID: PMC10404900 DOI: 10.1177/1945892420957853] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Post-viral olfactory dysfunction is a common cause of both short- and long-term smell alteration. The coronavirus pandemic further highlights the importance of post-viral olfactory dysfunction. Currently, a comprehensive review of the neural mechanism underpinning post-viral olfactory dysfunction is lacking. OBJECTIVES To synthesize the existing primary literature related to olfactory dysfunction secondary to viral infection, detail the underlying pathophysiological mechanisms, highlight relevance for the current COVID-19 pandemic, and identify high impact areas of future research. METHODS PubMed and Embase were searched to identify studies reporting primary scientific data on post-viral olfactory dysfunction. Results were supplemented by manual searches. Studies were categorized into animal and human studies for final analysis and summary. RESULTS A total of 38 animal studies and 7 human studies met inclusion criteria and were analyzed. There was significant variability in study design, experimental model, and outcome measured. Viral effects on the olfactory system varies significantly based on viral substrain but generally include damage or alteration in components of the olfactory epithelium and/or the olfactory bulb. CONCLUSIONS The mechanism of post-viral olfactory dysfunction is highly complex, virus-dependent, and involves a combination of insults at multiple levels of the olfactory pathway. This will have important implications for future diagnostic and therapeutic developments for patients infected with COVID-19.
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Affiliation(s)
- Jason C. Lee
- Department of Otolaryngology—Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, Kansas
| | - Rohit Nallani
- Department of Otolaryngology—Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, Kansas
| | - Lauren Cass
- Department of Otolaryngology—Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, Kansas
| | - Vidur Bhalla
- Saint Luke’s Hospital of Kansas City, Kansas City, Missouri
| | - Alexander G. Chiu
- Department of Otolaryngology—Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, Kansas
| | - Jennifer A. Villwock
- Department of Otolaryngology—Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, Kansas
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10
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Abstract
Due to the rapid spread of the SARS-CoV-2 virus, many health systems worldwide are overwhelmed, leading to the triggering of the scarcity of medical resources. The identification of indicators that require hospital admission help in the efficient allocation of medical resources. Olfactory impairment is also one of the indicators of COVID-19 infection. Many studies have analyzed olfactory dysfunction in COVID-19 with a variable prevalence rate but underreporting of this problem is very much likely as the problem is considered benign. Many scientific societies have stated that olfactory dysfunction is a frequent symptom of COVID-19 and have published recommendations for it.
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11
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Imam SA, Lao WP, Reddy P, Nguyen SA, Schlosser RJ. Is SARS-CoV-2 (COVID-19) postviral olfactory dysfunction (PVOD) different from other PVOD? World J Otorhinolaryngol Head Neck Surg 2020; 6:S26-S32. [PMID: 32837756 PMCID: PMC7236684 DOI: 10.1016/j.wjorl.2020.05.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 05/07/2020] [Accepted: 05/08/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The SARS-CoV-2 virus continues to spread rapidly across the globe afflicting many with Coronavirus Disease 2019 (COVID-19). As the infection rates rise, a growing number of SARS-CoV-2 positive individuals have been reported to complain of olfactory disturbances at an alarming rate. Postviral olfactory dysfunction (PVOD) is a well-known phenomenon that may explain the olfactory dysfunction reported by SARS-CoV-2 infected individuals. METHODS A scoping literature review was performed to identify studies that investigated the mechanisms of postviral olfactory dysfunction. Studies demonstrating pathophysiological, histological, immunochemical, and epidemiological outcomes of PVOD were included. RESULTS Fourteen studies were included in addition to one international news article. Three studies reported destruction of the olfactory epithelium following intranasal inoculation of various viral strains in mice. Three studies isolated pathogenic, anosmia inciting viruses (Parainfluenza virus, Human Coronavirus, Rhinovirus) through nucleic acid amplification. Eleven studies demonstrated female predilection in patients with PVOD and COVID-19 associated olfactory dysfunction, of which the majority were over 50 years old. CONCLUSIONS PVOD and COVID-19 associated olfactory dysfunction demonstrates considerable similarities in epidemiological trends and disease sequela of other viruses to suggest identical pathophysiological mechanisms. Further studies such as intranasal inoculation and histological biopsies are needed to support our hypothesis.
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Affiliation(s)
- Sarah A. Imam
- Department of Health and Human Performance, The Citadel, Charleston, SC, USA
| | - Wilson P. Lao
- Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - Priyanka Reddy
- Department of Otolaryngology- Head and Neck Surgery, Medical University of South Carolina, Charleston, SC, USA
| | - Shaun A. Nguyen
- Department of Otolaryngology- Head and Neck Surgery, Medical University of South Carolina, Charleston, SC, USA
| | - Rodney J. Schlosser
- Department of Otolaryngology- Head and Neck Surgery, Medical University of South Carolina, Charleston, SC, USA
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12
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Yazdanpanah N, Saghazadeh A, Rezaei N. Anosmia: a missing link in the neuroimmunology of coronavirus disease 2019 (COVID-19). Rev Neurosci 2020; 31:691-701. [PMID: 32776905 DOI: 10.1515/revneuro-2020-0039] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 07/19/2020] [Indexed: 12/22/2022]
Abstract
Just before 2020 began, a novel coronavirus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), brought for humans a potentially fatal disease known as coronavirus disease 2019 (COVID-19). The world has thoroughly been affected by COVID-19, while there has been little progress towards understanding the pathogenesis of COVID-19. Patients with a severe phenotype of disease and those who died from the disease have shown hyperinflammation and were more likely to develop neurological manifestations, linking the clinical disease with neuroimmunological features. Anosmia frequently occurs early in the course of COVID-19. The prevalence of anosmia would be influenced by self-diagnosis as well as self-misdiagnosis in patients with COVID-19. Despite this, the association between anosmia and COVID-19 has been a hope for research, aiming to understand the pathogenesis of COVID-19. Studies have suggested differently probable mechanisms for the development of anosmia in COVID-19, including olfactory cleft syndrome, postviral anosmia syndrome, cytokine storm, direct damage of olfactory sensory neurons, and impairment of the olfactory perception center in the brain. Thus, the observation of anosmia would direct us to find the pathogenesis of COVID-19 in the central nervous system, and this is consistent with numerous neurological manifestations related to COVID-19. Like other neurotropic viruses, SARS-CoV-2 might be able to enter the central nervous system via the olfactory epithelium and induce innate immune responses at the site of entry. Viral replication in the nonneural olfactory cells indirectly causes damage to the olfactory receptor nerves, and as a consequence, anosmia occurs. Further studies are required to investigate the neuroimmunology of COVID-19 in relation to anosmia.
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Affiliation(s)
- Niloufar Yazdanpanah
- Systematic Review and Meta-analysis Expert Group (SRMEG), Universal Scientific Education and Research Network (USERN), Tehran, 14194, Iran
- Research Center for Immunodeficiencies, Tehran University of Medical Sciences, Children's Medical Center, Dr. Qarib St, Keshavarz Blvd, Tehran, 14194, Iran
| | - Amene Saghazadeh
- Research Center for Immunodeficiencies, Tehran University of Medical Sciences, Children's Medical Center, Dr. Qarib St, Keshavarz Blvd, Tehran, 14194, Iran
- NeuroImmunology Research Association (NIRA), Universal Scientific Education and Research Network (USERN), Tehran, 14194, Iran
| | - Nima Rezaei
- Research Center for Immunodeficiencies, Tehran University of Medical Sciences, Children's Medical Center, Dr. Qarib St, Keshavarz Blvd, Tehran, 14194, Iran
- Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, 14194, Iran
- Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), Tehran, 14194, Iran
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13
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Glezer I, Bruni-Cardoso A, Schechtman D, Malnic B. Viral infection and smell loss: The case of COVID-19. J Neurochem 2020; 157:930-943. [PMID: 32970861 PMCID: PMC7537178 DOI: 10.1111/jnc.15197] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 12/19/2022]
Abstract
Olfactory disorders have been increasingly reported in individuals infected with SARS‐CoV‐2, the virus causing the coronavirus disease 2019 (COVID‐19). Losing the sense of smell has a strong impact on the quality of life, since it may lead to malnutrition, weight loss, food poisoning, depression, and exposure to dangerous chemicals. Individuals who suffer from anosmia (inability to smell) also cannot sense the flavor of food, which is a combination of taste and smell. Interestingly, infected individuals have reported sudden loss of smell with no congested nose, as is frequently observed in common colds or other upper respiratory tract infections. These observations suggest that SARS‐CoV‐2 infection leads to olfactory loss through a distinct mechanism, which is still unclear. This article provides an overview of olfactory loss and the recent findings relating to COVID‐19. Possible mechanisms of SARS‐CoV‐2‐induced olfactory loss are also discussed.
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Affiliation(s)
- Isaias Glezer
- Department of Biochemistry, UNIFESP, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Tres de Maio, São Paulo, Brazil
| | | | | | - Bettina Malnic
- Department of Biochemistry, University of São Paulo, São Paulo, Brazil
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14
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Baig AM, Sanders EC. Potential neuroinvasive pathways of SARS-CoV-2: Deciphering the spectrum of neurological deficit seen in coronavirus disease-2019 (COVID-19). J Med Virol 2020; 92:1845-1857. [PMID: 32492193 PMCID: PMC7300748 DOI: 10.1002/jmv.26105] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 05/26/2020] [Indexed: 12/15/2022]
Abstract
Coronavirus disease-2019 (COVID-19) was declared a global pandemic on 11 March 2020. Scientists and clinicians must acknowledge that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has the potential to attack the human body in multiple ways simultaneously and exploit any weaknesses of its host. A multipronged attack could potentially explain the severity and extensive variety of signs and symptoms observed in patients with COVID-19. Understanding the diverse tactics of this virus to infect the human body is both critical and incredibly complex. Although patients diagnosed with COVID-19 have primarily presented with pulmonary involvement, viral invasion, and injury to diverse end organs is also prevalent and well documented in these patients, but has been largely unheeded. Human organs known for angiotensin-converting enzyme 2 (ACE2) expression including the gastrointestinal tract, kidneys, heart, adrenals, brain, and testicles are examples of extra pulmonary tissues with confirmed invasion by SARS-CoV-2. Initial multiple organ involvement may present with vague signs and symptoms to alert health care professionals early in the course of COVID-19. Another example of an ongoing, yet neglected element of the syndromic features of COVID-19, are the reported findings of loss of smell, altered taste, ataxia, headache, dizziness, and loss of consciousness, which suggest a potential for neural involvement. In this review, we further deliberate on the neuroinvasive potential of SARS-CoV-2, the neurologic symptomology observed in COVID-19, the host-virus interaction, possible routes of SARS-CoV-2 to invade the central nervous system, other neurologic considerations for patients with COVID-19, and a collective call to action.
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Affiliation(s)
- Abdul Mannan Baig
- Department of Biological and Biomedical SciencesAga Khan UniversityKarachiSindhPakistan
| | - Erin C. Sanders
- Department of Obstetrics and GynecologyMount Auburn Hospital, Boston Urogynecology AssociatesCambridgeMassachusettsUnited States
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15
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Lee DJ, Lockwood J, Das P, Wang R, Grinspun E, Lee JM. Self-reported anosmia and dysgeusia as key symptoms of coronavirus disease 2019. CAN J EMERG MED 2020; 22:595-602. [PMID: 32507123 PMCID: PMC7308595 DOI: 10.1017/cem.2020.420] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
OBJECTIVES To slow down the transmission of coronavirus disease 2019 (COVID-19), it is important to identify specific symptoms for effective screening. While anosmia/hyposmia and dysgeusia/ageusia have been identified as highly prevalent symptoms, there are wide geographic variations, necessitating the regional evaluation of the prevalence of the symptoms. METHODS A cross-sectional study was performed to evaluate the self-reported symptoms among adults (over 18 years old) who underwent COVID-19 tests at an ambulatory assessment centre. We identified 1,345 patients (102 positive and 1,243 negative) who visited the assessment centre between March 16 and April 15, 2020. We randomly sampled negative patients in a 1:3 ratio. The primary outcome was the prevalence of self-reported anosmia/hyposmia and dysgeusia/ageusia. Logistic regression was performed to evaluate the association between COVID-19 positivity and loss of smell and taste. RESULTS Fifty-six of 102 (50%) positive patients and 72 of 306 (23.5%) negative patients completed the survey. Anosmia/hyposmia and dysgeusia/ageusia were more prevalent among COVID-19 positive patients (41.1% v. 4.2%, p < 0.001 for smell and 46.4% v. 5.6%, p < 0.001 for taste). Anosmia/hyposmia and dysgeusia/ageusia were independently highly associated with COVID-19 positivity (adjusted odds ratios 14.4 and 11.4 for smell and taste, respectively). CONCLUSION In this Canadian study, smell and taste loss may be key symptoms of COVID-19. This evidence can be helpful in the clinical diagnosis of COVID-19, particularly settings of limited testing capacity.
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Affiliation(s)
- Daniel J. Lee
- Department of Otolaryngology – Head and Neck Surgery, St. Michael's Hospital, Unity Health Toronto, University of Toronto, Toronto, ON
| | - Joel Lockwood
- Department of Emergency Medicine, St. Michael's Hospital, Unity Health Toronto, Toronto, ON
| | - Paul Das
- Department of Family and Community Medicine, St. Michael's Hospital, Unity Health Toronto, Toronto, ON
| | - Ri Wang
- MAP Centre for Urban Health Solutions, Li Ka-Shing Knowledge Institute, St. Michael's Hospital, Unity Health, Toronto, ON
| | - Eitan Grinspun
- Department of Computer Science, University of Toronto, Toronto, ON
| | - John M. Lee
- Department of Otolaryngology – Head and Neck Surgery, St. Michael's Hospital, Unity Health Toronto, University of Toronto, Toronto, ON
- Li Ka-Shing Knowledge Institute, St. Michael's Hospital, Unity Health Toronto, Toronto, ON
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16
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Zubair AS, McAlpine LS, Gardin T, Farhadian S, Kuruvilla DE, Spudich S. Neuropathogenesis and Neurologic Manifestations of the Coronaviruses in the Age of Coronavirus Disease 2019: A Review. JAMA Neurol 2020; 77:1018-1027. [PMID: 32469387 PMCID: PMC7484225 DOI: 10.1001/jamaneurol.2020.2065] [Citation(s) in RCA: 601] [Impact Index Per Article: 150.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Importance Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in December 2019, causing human coronavirus disease 2019 (COVID-19), which has now spread into a worldwide pandemic. The pulmonary manifestations of COVID-19 have been well described in the literature. Two similar human coronaviruses that cause Middle East respiratory syndrome (MERS-CoV) and severe acute respiratory syndrome (SARS-CoV-1) are known to cause disease in the central and peripheral nervous systems. Emerging evidence suggests COVID-19 has neurologic consequences as well. Observations This review serves to summarize available information regarding coronaviruses in the nervous system, identify the potential tissue targets and routes of entry of SARS-CoV-2 into the central nervous system, and describe the range of clinical neurological complications that have been reported thus far in COVID-19 and their potential pathogenesis. Viral neuroinvasion may be achieved by several routes, including transsynaptic transfer across infected neurons, entry via the olfactory nerve, infection of vascular endothelium, or leukocyte migration across the blood-brain barrier. The most common neurologic complaints in COVID-19 are anosmia, ageusia, and headache, but other diseases, such as stroke, impairment of consciousness, seizure, and encephalopathy, have also been reported. Conclusions and Relevance Recognition and understanding of the range of neurological disorders associated with COVID-19 may lead to improved clinical outcomes and better treatment algorithms. Further neuropathological studies will be crucial to understanding the pathogenesis of the disease in the central nervous system, and longitudinal neurologic and cognitive assessment of individuals after recovery from COVID-19 will be crucial to understand the natural history of COVID-19 in the central nervous system and monitor for any long-term neurologic sequelae.
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Affiliation(s)
- Adeel S Zubair
- Department of Neurology, Yale School of Medicine, New Haven, Connecticut
| | - Lindsay S McAlpine
- Department of Neurology, Yale School of Medicine, New Haven, Connecticut
| | - Tova Gardin
- Department of Neurology, Yale School of Medicine, New Haven, Connecticut
| | - Shelli Farhadian
- Division of Infectious Disease, Department of Medicine, Yale School of Medicine, New Haven, Connecticut
- Division of Neurological Infections and Global Neurology, Department of Neurology, Yale School of Medicine, New Haven, Connecticut
| | - Deena E Kuruvilla
- Division of Headache and Facial Pain, Department of Neurology, Yale School of Medicine, New Haven, Connecticut
| | - Serena Spudich
- Division of Neurological Infections and Global Neurology, Department of Neurology, Yale School of Medicine, New Haven, Connecticut
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17
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Brann DH, Tsukahara T, Weinreb C, Lipovsek M, Van den Berge K, Gong B, Chance R, Macaulay IC, Chou HJ, Fletcher RB, Das D, Street K, de Bezieux HR, Choi YG, Risso D, Dudoit S, Purdom E, Mill J, Hachem RA, Matsunami H, Logan DW, Goldstein BJ, Grubb MS, Ngai J, Datta SR. Non-neuronal expression of SARS-CoV-2 entry genes in the olfactory system suggests mechanisms underlying COVID-19-associated anosmia. SCIENCE ADVANCES 2020; 6:eabc5801. [PMID: 32937591 PMCID: PMC10715684 DOI: 10.1126/sciadv.abc5801] [Citation(s) in RCA: 678] [Impact Index Per Article: 169.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/18/2020] [Indexed: 05/05/2023]
Abstract
Altered olfactory function is a common symptom of COVID-19, but its etiology is unknown. A key question is whether SARS-CoV-2 (CoV-2) - the causal agent in COVID-19 - affects olfaction directly, by infecting olfactory sensory neurons or their targets in the olfactory bulb, or indirectly, through perturbation of supporting cells. Here we identify cell types in the olfactory epithelium and olfactory bulb that express SARS-CoV-2 cell entry molecules. Bulk sequencing demonstrated that mouse, non-human primate and human olfactory mucosa expresses two key genes involved in CoV-2 entry, ACE2 and TMPRSS2. However, single cell sequencing revealed that ACE2 is expressed in support cells, stem cells, and perivascular cells, rather than in neurons. Immunostaining confirmed these results and revealed pervasive expression of ACE2 protein in dorsally-located olfactory epithelial sustentacular cells and olfactory bulb pericytes in the mouse. These findings suggest that CoV-2 infection of non-neuronal cell types leads to anosmia and related disturbances in odor perception in COVID-19 patients.
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Affiliation(s)
- David H Brann
- Harvard Medical School Department of Neurobiology, Boston MA 02115 USA
| | - Tatsuya Tsukahara
- Harvard Medical School Department of Neurobiology, Boston MA 02115 USA
| | - Caleb Weinreb
- Harvard Medical School Department of Neurobiology, Boston MA 02115 USA
| | - Marcela Lipovsek
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London, London SE1 1UL, UK
| | - Koen Van den Berge
- Department of Statistics, University of California, Berkeley, CA 94720
- Department of Applied Mathematics, Computer Science and Statistics, Ghent University, Ghent, Belgium
| | - Boying Gong
- Division of Biostatistics, School of Public Health, University of California, Berkeley, CA 94720
| | - Rebecca Chance
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Iain C Macaulay
- Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ, UK
| | - Hsin-Jung Chou
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Russell B Fletcher
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- Present address: Surrozen, Inc., South San Francisco, CA 94080
| | - Diya Das
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- Berkeley Institute for Data Science, University of California, Berkeley
- Present address: Genentech, Inc., South San Francisco, CA 94080
| | - Kelly Street
- Department of Data Sciences, Dana-Farber Cancer Institute, Boston, MA
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA
| | - Hector Roux de Bezieux
- Division of Biostatistics, School of Public Health, University of California, Berkeley, CA 94720
- Center for Computational Biology, University of California, Berkeley, CA 94720
| | - Yoon-Gi Choi
- QB3 Functional Genomics Laboratory, University of California, Berkeley, CA 94720
| | - Davide Risso
- Department of Statistical Sciences, University of Padova, Padova, Italy
| | - Sandrine Dudoit
- Department of Statistics, University of California, Berkeley, CA 94720
- Division of Biostatistics, School of Public Health, University of California, Berkeley, CA 94720
| | - Elizabeth Purdom
- Department of Statistics, University of California, Berkeley, CA 94720
| | - Jonathan Mill
- University of Exeter Medical School, College of Medicine & Health, University of Exeter, Exeter EX2 5DW, UK
| | - Ralph Abi Hachem
- Duke University School of Medicine Department of Head and Neck Surgery & Communication Sciences, Durham, NC 27717 USA
| | - Hiroaki Matsunami
- Duke University School of Medicine Department of Molecular Genetics and Microbiology, Department of Neurobiology, Duke Institute for Brain Sciences, Durham, NC 27717 US
| | - Darren W Logan
- Waltham Petcare Science Institute, Leicestershire LE14 4RT, UK
| | - Bradley J Goldstein
- Duke University School of Medicine Department of Head and Neck Surgery & Communication Sciences, Durham, NC 27717 USA
| | - Matthew S Grubb
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London, London SE1 1UL, UK
| | - John Ngai
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- QB3 Functional Genomics Laboratory, University of California, Berkeley, CA 94720
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720
- Present address: National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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18
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Cooper KW, Brann DH, Farruggia MC, Bhutani S, Pellegrino R, Tsukahara T, Weinreb C, Joseph PV, Larson ED, Parma V, Albers MW, Barlow LA, Datta SR, Di Pizio A. COVID-19 and the Chemical Senses: Supporting Players Take Center Stage. Neuron 2020; 107:219-233. [PMID: 32640192 PMCID: PMC7328585 DOI: 10.1016/j.neuron.2020.06.032] [Citation(s) in RCA: 212] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 12/11/2022]
Abstract
The main neurological manifestation of COVID-19 is loss of smell or taste. The high incidence of smell loss without significant rhinorrhea or nasal congestion suggests that SARS-CoV-2 targets the chemical senses through mechanisms distinct from those used by endemic coronaviruses or other common cold-causing agents. Here we review recently developed hypotheses about how SARS-CoV-2 might alter the cells and circuits involved in chemosensory processing and thereby change perception. Given our limited understanding of SARS-CoV-2 pathogenesis, we propose future experiments to elucidate disease mechanisms and highlight the relevance of this ongoing work to understanding how the virus might alter brain function more broadly.
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Affiliation(s)
- Keiland W Cooper
- Interdepartmental Neuroscience Program, University of California Irvine, Irvine, CA, USA
| | - David H Brann
- Harvard Medical School Department of Neurobiology, Boston, MA, USA
| | | | - Surabhi Bhutani
- School of Exercise and Nutritional Sciences, San Diego State University, San Diego, CA, USA
| | - Robert Pellegrino
- Department of Food Science, Institute of Agriculture, University of Tennessee, Knoxville, TN, USA; Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
| | | | - Caleb Weinreb
- Harvard Medical School Department of Neurobiology, Boston, MA, USA
| | - Paule V Joseph
- Division of Intramural Research, National Institute of Nursing Research (NINR) National Institutes of Health, Bethesda, MD, USA; National Institute on Alcohol Abuse and Alcoholism (NIAAA) National Institutes of Health, Bethesda, MD, USA
| | - Eric D Larson
- Department of Otolaryngology, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA and the Rocky Mountain Taste and Smell Center, Aurora, CO, USA
| | - Valentina Parma
- Department of Psychology, Temple University, Philadelphia, PA, USA
| | - Mark W Albers
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Linda A Barlow
- Department of Cell and Developmental Biology, Graduate Program in Cell Biology, Stem Cells and Development and the Rocky Mountain Taste and Smell Center, University of Colorado, School Medicine, Anschutz Medical Campus, Aurora, CO, USA.
| | | | - Antonella Di Pizio
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany.
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19
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Han AY, Mukdad L, Long JL, Lopez IA. Anosmia in COVID-19: Mechanisms and Significance. Chem Senses 2020; 45:bjaa040. [PMID: 32556089 PMCID: PMC7449368 DOI: 10.1093/chemse/bjaa040] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Indexed: 12/13/2022] Open
Abstract
The global pandemic of coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 remains a challenge for prevention due to asymptomatic or paucisymptomatic patients. Anecdotal and preliminary evidence from multiple institutions shows that these patients present with a sudden onset of anosmia without rhinitis. We aim to review the pathophysiology of anosmia related to viral upper respiratory infections and the prognostic implications. Current evidence suggests that SARS-CoV-2-related anosmia may be a new viral syndrome specific to COVID-19 and can be mediated by intranasal inoculation of SARS-CoV-2 into the olfactory neural circuitry. The clinical course of neuroinvasion of SARS-CoV-2 is yet unclear, however an extended follow up of these patients to assess for neurological sequelae including encephalitis, cerebrovascular accidents and long-term neurodegenerative risk may be indicated.
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Affiliation(s)
- Albert Y Han
- Department of Head and Neck Surgery, University of California, Los Angeles, Rehabilitation Center 35–64, Los Angeles, CA, USA
| | - Laith Mukdad
- Department of Head and Neck Surgery, University of California, Los Angeles, Rehabilitation Center 35–64, Los Angeles, CA, USA
| | - Jennifer L Long
- Department of Head and Neck Surgery, University of California, Los Angeles, Rehabilitation Center 35–64, Los Angeles, CA, USA
- Greater Los Angeles VA Healthcare System, Los Angeles, CA, USA
| | - Ivan A Lopez
- Department of Head and Neck Surgery, University of California, Los Angeles, Rehabilitation Center 35–64, Los Angeles, CA, USA
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20
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Vaira LA, Salzano G, Fois AG, Piombino P, De Riu G. Potential pathogenesis of ageusia and anosmia in COVID-19 patients. Int Forum Allergy Rhinol 2020; 10:1103-1104. [PMID: 32342636 PMCID: PMC7267531 DOI: 10.1002/alr.22593] [Citation(s) in RCA: 162] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 04/21/2020] [Accepted: 04/21/2020] [Indexed: 11/09/2022]
Affiliation(s)
- Luigi Angelo Vaira
- Maxillofacial Surgery Unit, University Hospital of Sassari, Sassari, Italy
| | - Giovanni Salzano
- Maxillofacial Surgery Unit, University Hospital of Naples "Federico II", Naples, Italy
| | | | - Pasquale Piombino
- Maxillofacial Surgery Unit, University Hospital of Naples "Federico II", Naples, Italy
| | - Giacomo De Riu
- Maxillofacial Surgery Unit, University Hospital of Sassari, Sassari, Italy
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21
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Soler ZM, Patel ZM, Turner JH, Holbrook EH. A primer on viral-associated olfactory loss in the era of COVID-19. Int Forum Allergy Rhinol 2020; 10:814-820. [PMID: 32271490 PMCID: PMC7262311 DOI: 10.1002/alr.22578] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/02/2020] [Accepted: 04/03/2020] [Indexed: 12/20/2022]
Abstract
Early reports have suggested that smell loss may be an early symptom associated with the pandemic known as coronavirus disease 2019 (COVID‐19). The possibility that severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) might cause olfactory dysfunction is certainly plausible. Patients presenting to specialized smell clinics are commonly diagnosed with upper respiratory infection (URI)‐associated olfactory loss and most are presumed to be viral related. In acute phases of infection, it is common to experience some smell loss as a result of nasal inflammation, mucosal edema, and obstruction of airflow into the olfactory cleft. In most cases, these episodes of smell loss are self‐limiting and coincide with resolution of URI symptoms. However, in some cases the smell loss persists for months to years and this is presumed to occur through a more direct olfactory insult by the virus. It remains too early to know whether infection with SARS‐CoV‐2 causes persistent olfactory dysfunction. However, given the scale of this pandemic, if SARS‐CoV‐2 does cause chronic olfactory loss in even a small portion of those infected, then the overall population prevalence could be quite large. This review provides a brief, practical overview of viral‐associated olfactory loss, realizing that evidence related to COVID‐19 will likely not be clear for some time. Our goal is to highlight the existence and importance of this condition and provide information geared for both providers and patients. Practical suggestions regarding evaluation and treatment will be provided, realizing that there may be constraints on medical resources and the nature of this pandemic remains dynamic.
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Affiliation(s)
- Zachary M Soler
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston, SC
| | - Zara M Patel
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Palo Alto, CA
| | - Justin H Turner
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University, Nashville, TN
| | - Eric H Holbrook
- Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Massachusetts Eye and Ear, Boston, MA
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22
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Iravani B, Arshamian A, Ravia A, Mishor E, Snitz K, Shushan S, Roth Y, Perl O, Honigstein D, Weissgross R, Karagach S, Ernst G, Okamoto M, Mainen Z, Monteleone E, Dinnella C, Spinelli S, Mariño-Sánchez F, Ferdenzi C, Smeets M, Touhara K, Bensafi M, Hummel T, Sobel N, Lundström JN. Relationship between odor intensity estimates and COVID-19 prevalence prediction in a Swedish population. Chem Senses 2020; 45:bjaa034. [PMID: 32441744 PMCID: PMC7314115 DOI: 10.1093/chemse/bjaa034] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Indexed: 01/05/2023] Open
Abstract
In response to the COVID-19 pandemic, countries have implemented various strategies to reduce and slow the spread of the disease in the general population. For countries that have implemented restrictions on its population in a step-wise manner, monitoring of COVID-19 prevalence is of importance to guide decision on when to impose new, or when to abolish old, restrictions. We are here determining whether measures of odor intensity in a large sample can serve as one such measure. Online measures of how intense common household odors are perceived and symptoms of COVID-19 were collected from 2440 Swedes. Average odor intensity ratings were then compared to predicted COVID-19 population prevalence over time in the Swedish population and were found to closely track each other (r=-0.83). Moreover, we found that there was a large difference in rated intensity between individuals with and without COVID-19 symptoms and number of symptoms was related to odor intensity ratings. Finally, we found that individuals progressing from reporting no symptoms to subsequently reporting COVID-19 symptoms demonstrated a large drop in olfactory performance. These data suggest that measures of odor intensity, if obtained in a large and representative sample, can be used as an indicator of COVID-19 disease in the general population. Importantly, this simple measure could easily be implemented in countries without widespread access to COVID-19 testing or implemented as a fast early response before wide-spread testing can be facilitated.
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Affiliation(s)
- Behzad Iravani
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Artin Arshamian
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Psychology, Stockholm University, Stockholm, Sweden
| | - Aharon Ravia
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Eva Mishor
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Kobi Snitz
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Sagit Shushan
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
- Department of Otolaryngology—Head and Neck Surgery, Edith Wolfson Medical Center, Holon, Israel
| | - Yehudah Roth
- Department of Otolaryngology—Head and Neck Surgery, Edith Wolfson Medical Center, Holon, Israel
| | - Ofer Perl
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | | | - Reut Weissgross
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Shiri Karagach
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Gernot Ernst
- Vestre Viken, Kongsberg Hospital and Psychological Institute, University in Oslo, Forskningsveien, Oslo, Norway
| | - Masako Okamoto
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Zachary Mainen
- Champalimaud Research, Champalimaud Centre for the Unknown, Av. Brasília, Lisbon, Portugal
| | - Erminio Monteleone
- Department of Agriculture, Food, Environment and Forestry, University of Florence, Florence, Italy
| | - Caterina Dinnella
- Department of Agriculture, Food, Environment and Forestry, University of Florence, Florence, Italy
| | - Sara Spinelli
- Department of Agriculture, Food, Environment and Forestry, University of Florence, Florence, Italy
| | - Franklin Mariño-Sánchez
- Rhinology and Skull Base Surgery Unit, Otorhinolaryngology Department, Ramón y Cajal University Hospital, Madrid, Spain
| | - Camille Ferdenzi
- Lyon Neuroscience Research Center, CNRS—INSERM—University Claude Bernard of Lyon, Bron, France
| | - Monique Smeets
- Faculty of Social and Behavioral Sciences, Utrecht University, Heidelberglaan, CS Utrecht, the Netherlands
| | - Kazushige Touhara
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Moustafa Bensafi
- Lyon Neuroscience Research Center, CNRS—INSERM—University Claude Bernard of Lyon, Bron, France
| | - Thomas Hummel
- Smell and Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Fetscherstrasse, Dresden, Germany
| | - Noam Sobel
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Johan N Lundström
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Monell Chemical Senses Center, Philadelphia, PA, USA
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Abstract
Despite garnering minimal attention from the medical community overall, olfaction is indisputably critical in the manner in which we as humans interact with our surrounding environment. As the initial anatomical structure in the olfactory pathway, the nasal airway plays a crucial role in the transmission and perception of olfactory stimuli. The goal of this chapter is to provide a comprehensive overview of olfactory disturbances as it pertains to the sinonasal airway. This comprises an in-depth discussion of clinically relevant nasal olfactory anatomy and physiology, classification systems of olfactory disturbance, as well as the various etiologies and pathophysiologic mechanisms giving rise to this important disease entity. A systematic clinical approach to the diagnosis and clinical workup of olfactory disturbances is also provided in addition to an extensive review of the medical and surgical therapeutic modalities currently available.
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Affiliation(s)
- Joseph S. Schwartz
- Department of Otolaryngology—Head & Neck Surgery, McGill University, Montreal, QC, Canada
| | - Bobby A. Tajudeen
- Department of Otolaryngology—Head & Neck Surgery, Rush University, Chicago, IL, United States
| | - David W. Kennedy
- Department of Otorhinolaryngology—Head and Neck Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States,Correspondence to: David W. Kennedy, M.D., Department of Otorhinolaryngology—Head and Neck Surgery, Hospital of the University of Pennsylvania, 3400 Spruce St Ravdin 5, Philadelphia, PA 19104, United States. Tel: +1-215-662-6971, Fax: +1215-349-5977
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24
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Singh M, Khan RS, Dine K, Das Sarma J, Shindler KS. Intracranial Inoculation Is More Potent Than Intranasal Inoculation for Inducing Optic Neuritis in the Mouse Hepatitis Virus-Induced Model of Multiple Sclerosis. Front Cell Infect Microbiol 2018; 8:311. [PMID: 30234031 PMCID: PMC6132074 DOI: 10.3389/fcimb.2018.00311] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 08/14/2018] [Indexed: 01/30/2023] Open
Abstract
Neurotropic strains of mouse hepatitis virus (MHV) induce acute inflammation and chronic demyelination in the spinal cord and optic nerves mediated by axonal spread following intracranial inoculation in mice, with pathologic features similar to the human demyelinating disease multiple sclerosis. Spinal cord demyelination is also induced following intranasal inoculation with neurotropic MHV strains, however much higher viral doses are required as compared to intracranial inoculation. Recently, it was shown that intranasal administration of low concentrations of proteins leads to significant, rapid accumulation of protein in the optic nerve and in the eye, with only low levels reaching spinal cord and other brain regions. Thus, we examined whether intranasal inoculation with MHV at doses equivalent to those given intracranially could induce optic neuritis—inflammation, demyelination and loss of retinal ganglion cells (RGCs) in the optic nerve with or without inducing spinal cord demyelination. Four week old male C57BL/6J mice were inoculated intracranially with the recombinant demyelinating strain RSA59, or intranasally with RSA59 or the non-demyelinating strain RSMHV2 as control. One month post-inoculation, mice inoculated intracranially with RSA59 had significant myelin loss in both spinal cord and optic nerves, with significant loss of RGCs as well, consistent with prior studies. As expected, intranasal inoculation with RSA59 failed to induce demyelination in spinal cord; however, it also did not induce optic nerve demyelination. No acute inflammation was found, and no viral antigen was detected, in the optic nerve or retina 1 day after inoculation. Results confirm the neurotropic effects of RSA59 following intracranial inoculation, and suggest that direct infection with axonal transport of virus from brain to spinal cord and optic nerve is required to induce demyelinating disease. These studies suggest that MHV does not selectively concentrate in optic nerve and retina to sufficient levels to induce demyelination following intranasal inoculation. Intracranial inoculation should continue to be considered a preferred method for studies of MHV-induced optic neuritis and central nervous system (CNS) demyelinating disease.
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Affiliation(s)
- Manmeet Singh
- Department of Biological Science, Indian Institute of Science Education and Research Kolkata, Mohanpur, India
| | - Reas S Khan
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - Kimberly Dine
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - Jayasri Das Sarma
- Department of Biological Science, Indian Institute of Science Education and Research Kolkata, Mohanpur, India
| | - Kenneth S Shindler
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, United States
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25
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Wheeler DL, Sariol A, Meyerholz DK, Perlman S. Microglia are required for protection against lethal coronavirus encephalitis in mice. J Clin Invest 2018; 128:931-943. [PMID: 29376888 DOI: 10.1172/jci97229] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 12/12/2017] [Indexed: 11/17/2022] Open
Abstract
Recent findings have highlighted the role of microglia in orchestrating normal development and refining neural network connectivity in the healthy CNS. Microglia are not only vital cells in maintaining CNS homeostasis, but also respond to injury, infection, and disease by undergoing proliferation and changes in transcription and morphology. A better understanding of the specific role of microglia in responding to viral infection is complicated by the presence of nonmicroglial myeloid cells with potentially overlapping function in the healthy brain and by the rapid infiltration of hematopoietic myeloid cells into the brain in diseased states. Here, we used an inhibitor of colony-stimulating factor 1 receptor (CSF1R) that depletes microglia to examine the specific roles of microglia in response to infection with the mouse hepatitis virus (MHV), a neurotropic coronavirus. Our results show that microglia were required during the early days after infection to limit MHV replication and subsequent morbidity and lethality. Additionally, microglia depletion resulted in ineffective T cell responses. These results reveal nonredundant, critical roles for microglia in the early innate and virus-specific T cell responses and for subsequent host protection from viral encephalitis.
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Affiliation(s)
| | - Alan Sariol
- Interdisciplinary Graduate Program in Immunology
| | | | - Stanley Perlman
- Interdisciplinary Graduate Program in Immunology.,Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
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26
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Murine Olfactory Bulb Interneurons Survive Infection with a Neurotropic Coronavirus. J Virol 2017; 91:JVI.01099-17. [PMID: 28835503 DOI: 10.1128/jvi.01099-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 08/18/2017] [Indexed: 12/22/2022] Open
Abstract
Viral infection of the central nervous system (CNS) is complicated by the mostly irreplaceable nature of neurons, as the loss of neurons has the potential to result in permanent damage to brain function. However, whether neurons or other cells in the CNS sometimes survive infection and the effects of infection on neuronal function is largely unknown. To address this question, we used the rJHM strain (rJ) of mouse hepatitis virus (MHV), a neurotropic coronavirus that causes acute encephalitis in susceptible strains of mice. To determine whether neurons or other CNS cells survive acute infection with this virulent virus, we developed a recombinant JHMV that expresses Cre recombinase (rJ-Cre) and infected mice that universally expressed a silent (floxed) version of tdTomato. Infection of these mice with rJ-Cre resulted in expression of tdTomato in host cells. The results showed that some cells were able to survive the infection, as demonstrated by continued tdTomato expression after virus antigen could no longer be detected. Most notably, interneurons in the olfactory bulb, which are known to be inhibitory, represented a large fraction of the surviving cells. In conclusion, our results indicated that some neurons are resistant to virus-mediated cell death and provide a framework for studying the effects of prior coronavirus infection on neuron function.IMPORTANCE We developed a novel recombinant virus that allows the study of cells that survive an infection by a central nervous system-specific strain of murine coronavirus. Using this virus, we identified neurons and, to a lesser extent, nonneuronal cells in the brain that were infected during the acute phase of the infection and survived for approximately 2 weeks until the mice succumbed to the infection. We focused on neurons and glial cells within the olfactory bulb because the virus enters the brain at this site. Our results show that interneurons of the olfactory bulb were the primary cell type able to survive infection. Further, these results indicate that this system will be useful for functional and gene expression studies of cells in the brain that survive acute infection.
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27
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Kanaya K, Kondo K, Suzukawa K, Sakamoto T, Kikuta S, Okada K, Yamasoba T. Innate immune responses and neuroepithelial degeneration and regeneration in the mouse olfactory mucosa induced by intranasal administration of Poly(I:C). Cell Tissue Res 2014; 357:279-99. [PMID: 24744264 PMCID: PMC4077259 DOI: 10.1007/s00441-014-1848-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 02/11/2014] [Indexed: 01/12/2023]
Abstract
The pathogenesis of postviral olfactory disorder (PVOD) has not been fully elucidated. We investigated morphological changes and innate immune responses in the mouse olfactory mucosa induced by intranasal administration of polyinosinic-polycytidylic acid [Poly(I:C)], a synthetic analog of viral double-stranded RNA. Mice received three administrations of saline with or without Poly(I:C), once every 24 h. The olfactory mucosa was harvested at various intervals after the first administration (8 h, 3, 9 and 24 days). In the Poly(I:C) group, the number of apoptotic cells in the olfactory neuroepithelium had increased at 8 h. At 9 days, the olfactory neuroepithelium had severely degenerated and behavioral tests demonstrated that the mice showed signs of olfactory deterioration. At 24 days, the structure of the neuroepithelium had regenerated almost completely. Regarding the innate immune responses, many neutrophils had infiltrated the olfactory neuroepithelium at 8 h and had exuded into the nasal cavity by 3 days. Macrophages had also infiltrated the olfactory neuroepithelium at 8 h although to a lesser extent, but they still remained in the neuroepithelium at 24 days. Poly(I:C)-induced neuroepithelial damage was significantly inhibited by a neutrophil elastase inhibitor and was suppressed in neutropenic model mice. These findings suggest that the secondary damage caused by the neutrophil-mediated innate immune response plays an important role in the pathogenesis of PVOD.
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Affiliation(s)
- Kaori Kanaya
- Department of Otolaryngology-Head and Neck Surgery, The University of Tokyo Graduate School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
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28
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Abstract
In this study, we investigated the role of damage to the nasal mucosa in the shedding of prions into nasal samples as a pathway for prion transmission. Here, we demonstrate that prions can replicate to high levels in the olfactory sensory epithelium (OSE) in hamsters and that induction of apoptosis in olfactory receptor neurons (ORNs) in the OSE resulted in sloughing off of the OSE from nasal turbinates into the lumen of the nasal airway. In the absence of nasotoxic treatment, olfactory marker protein (OMP), which is specific for ORNs, was not detected in nasal lavage samples. However, after nasotoxic treatment that leads to apoptosis of ORNs, both OMP and prion proteins were present in nasal lavage samples. The cellular debris that was released from the OSE into the lumen of the nasal airway was positive for both OMP and the disease-specific isoform of the prion protein, PrP(Sc). By using the real-time quaking-induced conversion assay to quantify prions, a 100- to 1,000-fold increase in prion seeding activity was observed in nasal lavage samples following nasotoxic treatment. Since neurons replicate prions to higher levels than other cell types and ORNs are the most environmentally exposed neurons, we propose that an increase in ORN apoptosis or damage to the nasal mucosa in a host with a preexisting prion infection of the OSE could lead to a substantial increase in the release of prion infectivity into nasal samples. This mechanism of prion shedding from the olfactory mucosa could contribute to prion transmission.
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29
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Steel CD, Hahto SM, Ciavarra RP. Peripheral dendritic cells are essential for both the innate and adaptive antiviral immune responses in the central nervous system. Virology 2009; 387:117-26. [PMID: 19264338 DOI: 10.1016/j.virol.2009.01.032] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 11/18/2008] [Accepted: 01/22/2009] [Indexed: 12/25/2022]
Abstract
Intranasal application of vesicular stomatitis virus (VSV) causes acute infection of the central nervous system (CNS). However, VSV encephalitis is not invariably fatal, suggesting that the CNS may contain a professional antigen-presenting cell (APC) capable of inducing or propagating a protective antiviral immune response. To examine this possibility, we first characterized the cellular elements that infiltrate the brain as well as the activation status of resident microglia in the brains of normal and transgenic mice acutely ablated of peripheral dendritic cells (DCs) in vivo. VSV encephalitis was characterized by a pronounced infiltrate of myeloid cells (CD45(high)CD11b(+)) and CD8(+) T cells containing a subset that was specific for the immunodominant VSV nuclear protein epitope. This T cell response correlated temporally with a rapid and sustained upregulation of MHC class I expression on microglia, whereas class II expression was markedly delayed. Ablation of peripheral DCs profoundly inhibited the inflammatory response as well as infiltration of virus-specific CD8(+) T cells. Unexpectedly, the VSV-induced interferon-gamma (IFN-gamma) response in the CNS remained intact in DC-deficient mice. Thus, both the inflammatory and certain components of the adaptive primary antiviral immune response in the CNS are dependent on peripheral DCs in vivo.
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Affiliation(s)
- Christina D Steel
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, 700 W Olney Road, Norfolk, VA 23501, USA
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30
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Distribution and severity of spontaneous lesions in the neuroepithelium and Bowman's glands in mouse olfactory mucosa: age-related progression. Cell Tissue Res 2009; 335:489-503. [PMID: 19142664 DOI: 10.1007/s00441-008-0739-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Accepted: 11/27/2008] [Indexed: 10/21/2022]
Abstract
Age-related changes were examined in the distribution and severity of spontaneous lesions in the neuroepithelium and Bowman's glands in mouse olfactory mucosa. The olfactory mucosa of female ICR mice at postnatal ages from 10 days to 16 months were investigated histologically by hematoxylin and eosin staining, high-iron diamine-Alcian blue (HID-AB) staining, and immunohistochemistry for olfactory marker protein (OMP), betaIII tubulin (betaIIIT), and Ki67. The lesions in the neuroepithelium and Bowman's glands were quantitatively assessed by morphometric analyses of sections stained with anti-OMP antibody or HID-AB. The first appearance of neuroepithelial abnormality was observed in the dorsomedial portion of the olfactory mucosa in 5-month-old mice. The distribution and severity of lesions progressed with increasing age. In mildly affected epithelium in which OMP-positive olfactory receptor neurons (ORNs) were present but in smaller amounts, the numbers of betaIIIT-positive and Ki67-positive neuroepithelial cells tended to be increased, indicating that neurogenesis was upregulated in these areas. In contrast, severely affected epithelium in which OMP-positive ORNs were virtually absent showed high variability in the numbers of betaIIIT- and Ki67-positive cells among the areas examined, probably reflecting differences in the capacity of the basal cells remaining in the affected area to generate new neuronal cells. Histological analysis with HID-AB revealed that spontaneous lesions in Bowman's glands also occurred in aged mouse olfactory mucosa. Lesions in the neuroepithelium and underlying Bowman's glands tended to be spatially co-localized, suggesting a close association between pathogeneses in these two structures. Moreover, lesions in Bowman's glands were associated with changes in the biochemical composition of mucus on the olfactory mucosa. This information should prove useful in improving the understanding of the pathogenetic mechanisms underlying age-related changes in the peripheral olfactory system.
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31
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Nair A, Hunzeker J, Bonneau RH. Modulation of microglia and CD8(+) T cell activation during the development of stress-induced herpes simplex virus type-1 encephalitis. Brain Behav Immun 2007; 21:791-806. [PMID: 17349776 DOI: 10.1016/j.bbi.2007.01.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 12/20/2006] [Accepted: 01/08/2007] [Indexed: 01/07/2023] Open
Abstract
The central nervous system (CNS) has been shown to be vulnerable to a variety of insults in animals exposed to glucocorticoids. For example, psychological stress, a known inducer of glucocorticoid production, enhances the susceptibility of mice to herpes simplex virus type-1 (HSV-1) infection and results in the development of HSV-1 encephalitis (HSE). To determine the immune mechanisms by which stress promotes the development of HSE, we examined the role of the glucocorticoid receptor (GR) and the N-methyl-d-aspartate (NMDA) receptor in the development of HSE. Our findings demonstrate that blockade of either the GR or the NMDA receptor enhances survival following HSV-1 infection in stressed mice to levels similar to non-stressed mice. Subsequent studies determined the effect of GR and NMDA receptor blockade on immune function by specifically examining both microglia and CD8(+) T cell activation. Stress inhibited the expression of MHC class I by microglia and other brain-derived antigen presenting cells (CD45(hi)) independent of either the glucocorticoid receptor or the NMDA receptor, suggesting that stress-induced suppression of MHC class I expression in the brain does not affect survival during HSE. Blockade of the NMDA receptor, however, diminished HSV-1-induced increases in class I expression by CD45(hi) cells, suggesting that blockade of the NMDA receptor may limit CNS inflammation. Also, while CD8(+) T cell activation and function in the brain were not affected by stress, the number of CD8(+) T cells in the superficial cervical lymph nodes (SCLN) was decreased in stressed mice via GR-mediated mechanisms. These findings indicate that stress-induced hypocellularity is mediated by the GR while NMDA receptor activation is responsible for enhancing CNS inflammation. The combined effects of GR-mediated hypocellularity of the SCLN and NMDA receptor-mediated CNS inflammation during stress promote the development of HSE.
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MESH Headings
- Animals
- Brain/cytology
- Brain/immunology
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- CD8-Positive T-Lymphocytes/virology
- Cytokines/metabolism
- Disease Models, Animal
- Encephalitis, Herpes Simplex/immunology
- Encephalitis, Herpes Simplex/psychology
- Encephalitis, Herpes Simplex/virology
- Herpesvirus 1, Human/immunology
- Major Histocompatibility Complex/physiology
- Male
- Mice
- Mice, Inbred C57BL
- Microglia/immunology
- Microglia/metabolism
- Microglia/virology
- Receptors, Glucocorticoid/antagonists & inhibitors
- Receptors, Glucocorticoid/physiology
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/physiology
- Stress, Psychological/complications
- Stress, Psychological/immunology
- Stress, Psychological/virology
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Affiliation(s)
- Aji Nair
- Graduate Program in Neuroscience, The Pennsylvania State University College of Medicine, Milton S Hershey Medical Center, Hershey, PA 17033, USA
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32
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Venkatraman G, Behrens M, Pyrski M, Margolis FL. Expression of Coxsackie-Adenovirus receptor (CAR) in the developing mouse olfactory system. ACTA ACUST UNITED AC 2006; 34:295-305. [PMID: 16841169 DOI: 10.1007/s11068-005-8359-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Revised: 11/14/2005] [Accepted: 11/14/2005] [Indexed: 10/24/2022]
Abstract
Interest in manipulating gene expression in olfactory sensory neurons (OSNs) has led to the use of adenoviruses (AdV) as gene delivery vectors. OSNs are the first order neurons in the olfactory system and the initial site of odor detection. They are highly susceptible to adenovirus infection although the mechanism is poorly understood. The Coxsackie-Adenovirus receptor (CAR) and members of the integrin family have been implicated in the process of AdV infection in various systems. Multiple serotypes of AdV efficiently bind to the CAR, leading to entry and infection of the host cell by a mechanism that can also involve integrins. Cell lines that do not express CAR are relatively resistant, but not completely immune to AdV infection, suggesting that other mechanisms participate in mediating AdV attachment and entry. Using in situ hybridization and western blot analyses, we show that OSNs and olfactory bulbs (OB) of mice express abundant CAR mRNA at embryonic and neonatal stages, with progressive diminution during postnatal development. By contrast to the olfactory epithelium (OE), CAR mRNA is still present in the adult mouse OB. Furthermore, despite a similar postnatal decline, CAR protein expression in the OE and OB of mice continues into adulthood. Our results suggest that the robust AdV infection observed in the postnatal olfactory system is mediated by CAR and that expression of even small amounts of CAR protein as seen in the adult rodent, permits efficient AdV infection and entry. CAR is an immunoglobulin domain-containing protein that bears homology to cell-adhesion molecules suggesting the possibility that it may participate in organization of the developing olfactory system.
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Affiliation(s)
- Giri Venkatraman
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, 21201, USA
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33
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Abstract
Clinical assessment of the patient who has smell and taste disorders requires understanding of the etiology of the olfactory and gustatory disorders. Available clinical tests of olfactory and gustatory systems allow detecting and measuring the degree of the sensory loss, but are unable to determine the cause and give neither prognostic information nor therapeutic guidance. With physical examination, however, clinical history can help to establish the diagnosis and guide the treatment if available. A clinician evaluating a patient who has smell and taste loss must understand that "taste" complaints usually are symptoms of an olfactory dysfunction. The distinction between true gustatory loss (bitter, sweet, salty, sour, or umami) and olfactory loss, the inability to perceive complex flavors of food, will help clarify the patient's diagnosis. Easy-to-administer tests are available for olfactory (eg, UPSIT) and gustatory testing (eg, spatial tests, taste sticks, tasting tablets). In rare circumstances, imaging studies (eg, MRI, CT) are indicated.
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34
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Li H, Wood CL, Getchell TV, Getchell ML, Stromberg AJ. Analysis of oligonucleotide array experiments with repeated measures using mixed models. BMC Bioinformatics 2004; 5:209. [PMID: 15626348 PMCID: PMC544885 DOI: 10.1186/1471-2105-5-209] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2004] [Accepted: 12/30/2004] [Indexed: 11/12/2022] Open
Abstract
Background Two or more factor mixed factorial experiments are becoming increasingly common in microarray data analysis. In this case study, the two factors are presence (Patients with Alzheimer's disease) or absence (Control) of the disease, and brain regions including olfactory bulb (OB) or cerebellum (CER). In the design considered in this manuscript, OB and CER are repeated measurements from the same subject and, hence, are correlated. It is critical to identify sources of variability in the analysis of oligonucleotide array experiments with repeated measures and correlations among data points have to be considered. In addition, multiple testing problems are more complicated in experiments with multi-level treatments or treatment combinations. Results In this study we adopted a linear mixed model to analyze oligonucleotide array experiments with repeated measures. We first construct a generalized F test to select differentially expressed genes. The Benjamini and Hochberg (BH) procedure of controlling false discovery rate (FDR) at 5% was applied to the P values of the generalized F test. For those genes with significant generalized F test, we then categorize them based on whether the interaction terms were significant or not at the α-level (αnew = 0.0033) determined by the FDR procedure. Since simple effects may be examined for the genes with significant interaction effect, we adopt the protected Fisher's least significant difference test (LSD) procedure at the level of αnew to control the family-wise error rate (FWER) for each gene examined. Conclusions A linear mixed model is appropriate for analysis of oligonucleotide array experiments with repeated measures. We constructed a generalized F test to select differentially expressed genes, and then applied a specific sequence of tests to identify factorial effects. This sequence of tests applied was designed to control for gene based FWER.
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Affiliation(s)
- Hao Li
- Department of Statistics, 815 Patterson Office Tower, University of Kentucky, Lexington, Kentucky 40506-0027, USA
| | - Constance L Wood
- Department of Statistics, 815 Patterson Office Tower, University of Kentucky, Lexington, Kentucky 40506-0027, USA
| | - Thomas V Getchell
- Department of Physiology, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0298, USA
- 309 Sanders-Brown Center on Aging, 800 South Limestone Street, University of Kentucky College of Medicine, Lexington, KY 40536-0230, USA
| | - Marilyn L Getchell
- Department of Anatomy and Neurobiology, College of Medicine, Univeristy of Kentucky, Lexington, KY 40536-0298, USA
- 309 Sanders-Brown Center on Aging, 800 South Limestone Street, University of Kentucky College of Medicine, Lexington, KY 40536-0230, USA
| | - Arnold J Stromberg
- Department of Statistics, 815 Patterson Office Tower, University of Kentucky, Lexington, Kentucky 40506-0027, USA
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35
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Abstract
Disorders of taste and smell can present a challenge to the facial plastic surgeon. Obtaining a detailed history and examination is the key to the diagnosis and work-up of olfactory and gustatory dysfunction. Easy-to-administer tests are available for olfactory evaluation(University of Pennsylvania Smell Identification Test) and gustatory (taste sticks, tasting tablets) evaluation. The prognosis and management of olfactory and gustatory disease depend on its etiology. Despite ongoing research, the treatment of the disorders of smell and taste is limited.
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Affiliation(s)
- Bozena B Wrobel
- Department of Otolaryngology-Head and Neck Surgery, University of Nebraska, 981225 Nebraska Medical Center, Omaha, NE 68198-1225, USA
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36
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Abstract
Disorders of the sense of smell can be frustrating for both the patient and physician. Ongoing research in this field has provided insight into the possible mechanisms for smell loss; however, therapy is still limited. Commercially distributed smell testing kits and newer screening tests using material available in all clinical settings have made diagnosis and measurement of the degree of impairment available to all physicians. A detailed history and physical examination are the most powerful tools in the evaluation of smell disorders, whereas imaging studies are reserved for preoperative planning or detailed assessment of positive physical findings.
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Affiliation(s)
- Eric H Holbrook
- Department of Otolaryngology-Head and Neck Surgery, University of Nebraska Medical Center, Omaha, Nebraska 68198-1225, USA
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37
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Schwob JE. Neural regeneration and the peripheral olfactory system. THE ANATOMICAL RECORD 2002; 269:33-49. [PMID: 11891623 DOI: 10.1002/ar.10047] [Citation(s) in RCA: 364] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The peripheral olfactory system is able to recover after injury, i.e., the olfactory epithelium reconstitutes, the olfactory nerve regenerates, and the olfactory bulb is reinnervated, with a facility that is unique within the mammalian nervous system. Cell renewal in the epithelium is directed to replace neurons when they die in normal animals and does so at an accelerated pace after damage to the olfactory nerve. Neurogenesis persists because neuron-competent progenitor cells, including transit amplifying and immediate neuronal precursors, are maintained within the population of globose basal cells. Notwithstanding events in the neuron-depleted epithelium, the death of both non-neuronal cells and neurons directs multipotent globose basal cell progenitors, to give rise individually to sustentacular cells and horizontal basal cells as well as neurons. Multiple growth factors, including TGF-alpha, FGF2, BMPs, and TGF-betas, are likely to be central in regulating choice points in epitheliopoiesis. Reinnervation of the bulb is rapid and robust. When the nerve is left undisturbed, i.e., by lesioning the epithelium directly, the projection of the reconstituted epithelium onto the bulb is restored to near-normal with respect to rhinotopy and in the targeting of odorant receptor-defined neuronal classes to small clusters of glomeruli in the bulb. However, at its ultimate level, i.e., the convergence of axons expressing the same odorant receptor onto one or a few glomeruli, specificity is not restored unless a substantial number of fibers of the same type are spared. Rather, odorant receptor-defined subclasses of neurons innervate an excessive number of glomeruli in the rough vicinity of their original glomerular targets.
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Affiliation(s)
- James E Schwob
- Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, MA 02111, USA.
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Youngentob SL, Schwob JE, Saha S, Manglapus G, Jubelt B. Functional consequences following infection of the olfactory system by intranasal infusion of the olfactory bulb line variant (OBLV) of mouse hepatitis strain JHM. Chem Senses 2001; 26:953-63. [PMID: 11595672 PMCID: PMC7110209 DOI: 10.1093/chemse/26.8.953] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The present study assessed the functional consequences of viral infection with a neurotropic coronavirus, designated MHV OBLV, that specifically targets central olfactory structures. Using standard operant techniques and a 'go, no-go' successive discrimination paradigm, six BALB/c mice were trained to discriminate between the presentation of an air or odor stimulus (three mice for each of the odorants propanol and propyl acetate). Two additional BALB/c mice were trained to discriminate between the presentation of air and the presentation of either vanillin or propionic acid. Following criterion performance, each mouse received an additional 2000 trials of overtraining. At completion of overtraining one mouse from the propanol and propyl acetate groups were allocated as untreated. The remaining six mice were inoculated with 300 microl of the OBLV stock per nostril for a total of 1.5 x 10(6) p.f.u. in 600 microl. Following a 1 month rest, untreated and inoculated animals were again tested on their respective air versus odor discrimination task. Untreated animals immediately performed at criterion levels. In contrast, inoculated animals varied in their capacity to discriminate between air and odorant. Five of the six inoculated mice showed massive disruption of the olfactory bulb, including death of mitral cells; the other was more modestly affected. In addition, the density of innervation of the olfactory mucosa by substance P-containing trigeminal fibers is also affected by inoculation. Those mice that remained anosmic to the training odorants had the most severe reduction in mitral cell number and substance P fiber density among the inoculated animals.
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Affiliation(s)
- S L Youngentob
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY 13210, USA.
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