SARS-CoV-2 infection causes transient olfactory dysfunction in mice

2020 ◽  
Author(s):  
Qing Ye ◽  
Jia Zhou ◽  
Guan Yang ◽  
Rui-Ting Li ◽  
Qi He ◽  
...  

AbstractOlfactory dysfunction caused by SARS-CoV-2 infection represents as one of the most predictive and common symptoms in COVID-19 patients. However, the causal link between SARS-CoV-2 infection and olfactory disorders remains lacking. Herein we demonstrate intranasal inoculation of SARS-CoV-2 induces robust viral replication in the olfactory epithelium (OE), resulting in transient olfactory dysfunction in humanized ACE2 mice. The sustentacular cells and Bowman’s gland cells in OE were identified as the major targets of SARS-CoV-2 before the invasion into olfactory sensory neurons. Remarkably, SARS-CoV-2 infection triggers cell death and immune cell infiltration, and impairs the uniformity of OE structure. Combined transcriptomic and proteomic analyses reveal the induction of antiviral and inflammatory responses, as well as the downregulation of olfactory receptors in OE from the infected animals. Overall, our mouse model recapitulates the olfactory dysfunction in COVID-19 patients, and provides critical clues to understand the physiological basis for extrapulmonary manifestations of COVID-19.

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Qing Ye ◽  
Jia Zhou ◽  
Qi He ◽  
Rui-Ting Li ◽  
Guan Yang ◽  
...  

AbstractSARS-CoV-2 infection causes a wide spectrum of clinical manifestations in humans, and olfactory dysfunction is one of the most predictive and common symptoms in COVID-19 patients. However, the underlying mechanism by which SARS-CoV-2 infection leads to olfactory disorders remains elusive. Herein, we demonstrate that intranasal inoculation with SARS-CoV-2 induces robust viral replication in the olfactory epithelium (OE), not the olfactory bulb (OB), resulting in transient olfactory dysfunction in humanized ACE2 (hACE2) mice. The sustentacular cells and Bowman’s gland cells in the OE were identified as the major target cells of SARS-CoV-2 before invasion into olfactory sensory neurons (OSNs). Remarkably, SARS-CoV-2 infection triggers massive cell death and immune cell infiltration and directly impairs the uniformity of the OE structure. Combined transcriptomic and quantitative proteomic analyses revealed the induction of antiviral and inflammatory responses, as well as the downregulation of olfactory receptor (OR) genes in the OE from the infected animals. Overall, our mouse model recapitulates olfactory dysfunction in COVID-19 patients and provides critical clues for understanding the physiological basis for extrapulmonary manifestations of COVID-19.


Author(s):  
Anna Jinxia Zhang ◽  
Andrew Chak-Yiu Lee ◽  
Hin Chu ◽  
Jasper Fuk-Woo Chan ◽  
Zhimeng Fan ◽  
...  

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.


PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0249029
Author(s):  
Fabrice Neiers ◽  
David Jarriault ◽  
Franck Menetrier ◽  
Loïc Briand ◽  
Jean-Marie Heydel

Odorant metabolizing enzymes (OMEs) are expressed in the olfactory epithelium (OE) where they play a significant role in the peripheral olfactory process by catalyzing the fast biotransformation of odorants leading either to their elimination or to the synthesis of new odorant stimuli. The large family of OMEs gathers different classes which interact with a myriad of odorants alike and complementary to olfactory receptors. Thus, it is necessary to increase our knowledge on OMEs to better understand their function in the physiological process of olfaction. This study focused on a major olfactory UDP-glucuronosyltransferase (UGT): UGT2A1. Immunohistochemistry and immunogold electronic microscopy allowed to localize its expression in the apical part of the sustentacular cells and originally at the plasma membrane of the olfactory cilia of the olfactory sensory neurons, both locations in close vicinity with olfactory receptors. Moreover, using electroolfactogram, we showed that a treatment of the OE with beta-glucuronidase, an enzyme which counterbalance the UGTs activity, increased the response to eugenol which is a strong odorant UGT substrate. Altogether, the results supported the function of the olfactory UGTs in the vertebrate olfactory perireceptor process.


2021 ◽  
Vol 12 ◽  
Author(s):  
Juehong Li ◽  
Ziyang Sun ◽  
Gang Luo ◽  
Shuo Wang ◽  
Haomin Cui ◽  
...  

Heterotopic ossification (HO) is one of the most intractable disorders following musculoskeletal injury and is characterized by the ectopic presence of bone tissue in the soft tissue leading to severe loss of function in the extremities. Recent studies have indicated that immune cell infiltration and inflammation are involved in aberrant bone formation. In this study, we found increased monocyte/macrophage and mast cell accumulation during early HO progression. Macrophage depletion by clodronate liposomes and mast cell stabilization by cromolyn sodium significantly impeded HO formation. Therefore, we proposed that the dietary phytochemical quercetin could also suppress immune cell recruitment and related inflammatory responses to prevent HO. As expected, quercetin inhibited the monocyte-to-macrophage transition, macrophage polarization, and mast cell activation in vitro in a dose-dependent manner. Using a murine burn/tenotomy model, we also demonstrated that quercetin attenuated inflammatory responses and HO in vivo. Furthermore, elevated SIRT1 and decreased acetylated NFκB p65 expression were responsible for the mechanism of quercetin, and the beneficial effects of quercetin were reversed by the SIRT1 antagonist EX527 and mimicked by the SIRT agonist SRT1720. The findings in this study suggest that targeting monocyte/macrophage and mast cell activities may represent an attractive approach for therapeutic intervention of HO and that quercetin may serve as a promising therapeutic candidate for the treatment of trauma-induced HO by modulating SIRT1/NFκB signaling.


2022 ◽  
Vol 2022 ◽  
pp. 1-24
Author(s):  
Bin-Bin Da ◽  
Shuai Luo ◽  
Ming Huang ◽  
Fei Song ◽  
Rong Ding ◽  
...  

It has been demonstrated that the inflammatory response influences cancer development and can be used as a prognostic biomarker in various tumors. However, the relevance of genes associated with inflammatory responses in hepatocellular carcinoma (HCC) remains unknown. The Cancer Genome Atlas (TCGA) database was analyzed using weighted gene coexpression network analysis (WGCNA) and differential analysis to discover essential inflammatory response-related genes (IFRGs). Cox regression studies, both univariate and multivariate, were employed to develop a prognostic IFRGs signature. Additionally, Gene Set Enrichment Analysis (GSEA) was used to deduce the biological function of the IFRGs signature. Finally, we estimated immune cell infiltration using a single sample GSEA (ssGSEA) and x-cell. Our results revealed that, among the major HCC IFRGs, two (DNASE1L3 and KLKB1) were employed to create a predictive IFRG signature. The IFRG signature could correctly predict overall survival (O.S) as per Kaplan-Meier time-dependent roc curves analysis. It was also linked to pathological tumor stage and T stage and might be used as a prognostic predictor in HCC. GSEA analysis concluded that the IFRG signature might influence the immune response in HCC. Immunological cell infiltration and immune checkpoint molecule expression differed in the high-risk and low-risk groups. As a result of our findings, DNASILE may play a role in the tumor microenvironment. However, more research is necessary to confirm the role of DNASE1L3 and KLKB1.


2015 ◽  
Vol 53 (12) ◽  
Author(s):  
AB Widera ◽  
L Pütter ◽  
S Leserer ◽  
G Campos ◽  
K Rochlitz ◽  
...  

Author(s):  
Lu Yuan ◽  
Xixi Wu ◽  
Longshan Zhang ◽  
Mi Yang ◽  
Xiaoqing Wang ◽  
...  

AbstractPulmonary surfactant protein A1 (SFTPA1) is a member of the C-type lectin subfamily that plays a critical role in maintaining lung tissue homeostasis and the innate immune response. SFTPA1 disruption can cause several acute or chronic lung diseases, including lung cancer. However, little research has been performed to associate SFTPA1 with immune cell infiltration and the response to immunotherapy in lung cancer. The findings of our study describe the SFTPA1 expression profile in multiple databases and was validated in BALB/c mice, human tumor tissues, and paired normal tissues using an immunohistochemistry assay. High SFTPA1 mRNA expression was associated with a favorable prognosis through a survival analysis in lung adenocarcinoma (LUAD) samples from TCGA. Further GeneOntology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses showed that SFTPA1 was involved in the toll-like receptor signaling pathway. An immune infiltration analysis clarified that high SFTPA1 expression was associated with an increased number of M1 macrophages, CD8+ T cells, memory activated CD4+ T cells, regulatory T cells, as well as a reduced number of M2 macrophages. Our clinical data suggest that SFTPA1 may serve as a biomarker for predicting a favorable response to immunotherapy for patients with LUAD. Collectively, our study extends the expression profile and potential regulatory pathways of SFTPA1 and may provide a potential biomarker for establishing novel preventive and therapeutic strategies for lung adenocarcinoma.


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