Anna Jinxia Zhang1,2,3, Andrew Chak-Yiu Lee2, Hin Chu1,2,3, Jasper Fuk-Woo Chan1,2,3,4, Zhimeng Fan2, Can Li2, Feifei Liu2, Yanxia Chen2, Shuofeng Yuan1,2,3, Vincent Kwok-Man Poon2, Chris Chung-Sing Chan2, Jian-Piao Cai2, Kenneth Lap-Kei Wu5,6, Siddharth Sridhar1,2,3,4, Ying-Shing Chan5,6, Kwok-Yung Yuen1,2,3,4. 1. State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China. 2. Department of Microbiology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China. 3. Carol Yu Centre for Infection, University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China. 4. Department of Microbiology, Queen Mary Hospital, Pokfulam, Hong Kong Special Administrative Region, China. 5. School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China. 6. State Key Laboratory of Brain and Cognitive Sciences, University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.
Abstract
BACKGROUND: Coronavirus disease 2019 (COVID-19) is primarily an acute respiratory tract infection. Distinctively, a substantial proportion of COVID-19 patients develop olfactory dysfunction. Especially in young patients, loss of smell can be the first or only symptom. The roles of inflammatory obstruction of the olfactory clefts, inflammatory cytokines affecting olfactory neuronal function, destruction of olfactory neurons or their supporting cells, and direct invasion of olfactory bulbs in causing olfactory dysfunction are uncertain. METHODS: We investigated the location for the pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from the olfactory epithelium (OE) to the olfactory bulb in golden Syrian hamsters. RESULTS: After intranasal inoculation with SARS-CoV-2, inflammatory cell infiltration and proinflammatory cytokine/chemokine responses were detected in the nasal turbinate tissues. The responses peaked between 2 and 4 days postinfection, with the highest viral load detected at day 2 postinfection. In addition to the pseudo-columnar ciliated respiratory epithelial cells, SARS-CoV-2 viral antigens were also detected in the mature olfactory sensory neurons labeled by olfactory marker protein, in the less mature olfactory neurons labeled by neuron-specific class III β-tubulin at the more basal position, and in the sustentacular cells, resulting in apoptosis and severe destruction of the OE. During the entire course of infection, SARS-CoV-2 viral antigens were not detected in the olfactory bulb. CONCLUSIONS: In addition to acute inflammation at the OE, infection of mature and immature olfactory neurons and the supporting sustentacular cells by SARS-CoV-2 may contribute to the unique olfactory dysfunction related to COVID-19, which is not reported with SARS-CoV-2.
BACKGROUND:Coronavirus disease 2019 (COVID-19) is primarily an acute respiratory tract infection. Distinctively, a substantial proportion of COVID-19patients develop olfactory dysfunction. Especially in young patients, loss of smell can be the first or only symptom. The roles of inflammatory obstruction of the olfactory clefts, inflammatory cytokines affecting olfactory neuronal function, destruction of olfactory neurons or their supporting cells, and direct invasion of olfactory bulbs in causing olfactory dysfunction are uncertain. METHODS: We investigated the location for the pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from the olfactory epithelium (OE) to the olfactory bulb in golden Syrian hamsters. RESULTS: After intranasal inoculation with SARS-CoV-2, inflammatory cell infiltration and proinflammatory cytokine/chemokine responses were detected in the nasal turbinate tissues. The responses peaked between 2 and 4 days postinfection, with the highest viral load detected at day 2 postinfection. In addition to the pseudo-columnar ciliated respiratory epithelial cells, SARS-CoV-2 viral antigens were also detected in the mature olfactory sensory neurons labeled by olfactory marker protein, in the less mature olfactory neurons labeled by neuron-specific class III β-tubulin at the more basal position, and in the sustentacular cells, resulting in apoptosis and severe destruction of the OE. During the entire course of infection, SARS-CoV-2 viral antigens were not detected in the olfactory bulb. CONCLUSIONS: In addition to acute inflammation at the OE, infection of mature and immature olfactory neurons and the supporting sustentacular cells by SARS-CoV-2 may contribute to the unique olfactory dysfunction related to COVID-19, which is not reported with SARS-CoV-2.
Authors: Samuel N Helman; Jonah Adler; Aria Jafari; Sasha Bennett; Jackson R Vuncannon; Ashley C Cozart; Sarah K Wise; Merin E Kuruvilla; Joshua M Levy Journal: Allergy Asthma Proc Date: 2022-03-01 Impact factor: 2.587
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