Project description:The nasal epithelium is the primary initial site of SARS-CoV-2 entry in the human body. Since much of the molecular detail defining coronavirus entry and replication was derived from non-nasal cell lines, it remains unclear how SARS-CoV-2 overcomes the physical nasal mucus and periciliary mucin layers to infect and spread through the nasal epithelium. Using air-liquid interface cultured primary nasal epithelial cells, we observed that SARS-CoV-2 attaches to motile cilia during the initial stage of infection. Depletion of cilia inhibited SARS-CoV-2, as well as respiratory syncytial virus and parainfluenza virus infection, suggesting a widely-used ciliary mechanism for respiratory viral entry. Using electron and immunofluorescence microscopy, we further observed that SARS-CoV-2 progeny virions attached to airway microvilli 24 hours post infection and triggered the formation of apically extended and highly branched microvilli that organize viral egress from the microvillar base back into the mucus layer, supporting a model of virus dispersion throughout airway tissue via mucociliary transport. Chemical perturbation of microvillus formation severely impaired viral egress and subsequent spread. Phosphoproteomic analyses indicate that virally-triggered microvillar branching is linked to the p21-activated kinase 1 and 4 (PAK1/4) signaling pathway and viral infection is impaired by PAK1/4 kinase inhibitors. Our work provides insight into the mechanisms by which SARS-CoV-2 and potentially many respiratory viruses penetrate the physical nasal epithelium barrier, a first line of defense against pathogens, thus revealing a new view of the motile cilia and microvilli as critical host factors required for viral entry and egress.
Project description:1. Odors are detected, firstly, by olfactory sensory neurons (OSNs) in the olfactory epithelium of the nose. This neurons then project directly to the olfactory bulb in the brain. Olfaction depends on cellular regeneration of the OE, olfactory bulb and hippocampus, and on their continual re-wiring. The olfactory neural pathway includes regions of the frontal, temporal and limbic brain, which in turn overlap with brain areas involved in brain disorders. OSNs are the only aspect of the human brain exposed to the external environment. This not only makes them vulnerable to environmental changes, but also accessible for biomedical studies.
We have already sequenced and developed a protocol for analyzing the transcriptome of mouse main olfactory epithelium and single OSNs. We propose here to perform a similar study for samples from the human olfactory epithelium.
We have developed a minimally invasive method for obtaining human OSNs, among other cells from the nasal epithelium. In this experiment, we have obtained cell samples from the olfactory epithelium, including OSN, from healthy volunteers. We would like to further characterize them by RNA sequencing. This will give us valuable insight into human olfaction. It will also provide a first step into a new avenue to study, and find biomarkers for, brain diseases though the analysis of these easily available neurons.
This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/
Project description:Diesel exhaust particles (DEPs), a major component of airborne particulate matter (PM), are strongly associated with the development of both acute and chronic upper airway inflammatory diseases. In this study, we investigated the effects of prolonged daily exposure to low-dose DEPs on the maturation of primary human nasal epithelium (PHNE). PHNE cultured under air-liquid interface (ALI) conditions were exposed to 0.5μg cm-² of DEPs for 5 hours daily from ALI day 1 to day 23. PHNE samples were subsequently collected on ALI days 6, 12, and 24 and analyzed using mass spectrometry-based label-free quantitative proteomics. A total of 7,993 proteins were identified, with approximately half exhibiting time-dependent differential expression patterns throughout the course of PHNE maturation. To determine the proteins differentially expressed in response to DEP exposure, we conducted paired Student’s t-tests at each time point. Functional annotation clustering of these differentially expressed proteins revealed enrichment of gene ontology (GO) terms related to the inflammatory response on ALI day 6. By ALI day 24, several GO biological process (GO-BP) terms associated with cilia—such as cilium assembly, intraciliary transport, and cilium movement—were significantly enriched. In conclusion, our findings suggest that repeated daily exposure to low-dose DEPs can trigger an immune response via IL-1α and IL-17 signaling pathways during the early stages of PHNE maturation and further affect ciliogenesis by disrupting cilia assembly and motility during later stage of PHNE maturation.