ABSTRACT: Although tropism of SARS-CoV-2 for respiratory tract epithelial cells is well established, an open question is whether the conjunctival epithelium is also a target for SARS-CoV-2. Conjunctival epithelial cells, which express viral entry receptors ACE2 and TMPRSS2, constitute the largest exposed epithelium of the ocular surface tissue, and may represent a relevant viral entry route. To address this question, we generated an organotypic air-liquid-interface model of conjunctival epithelium, composed of progenitor, basal and superficial epithelial cells and fibroblasts, which could be maintained successfully up to day 75 of differentiation. Using single cell RNA-Seq, with complementary imaging and virological assays, we observed that while all conjunctival cell types were permissive to SARS-CoV-2 genome expression, a productive infection did not ensure. The early innate immune response to SARS-CoV-2 infection in conjunctival cells was characterised by a robust NF-Kβ activity, alongside evidence of suppression of antiviral interferon signalling. Collectively these data enrich our understanding of SARS-CoV-2 infection at the human ocular surface, with potential implications for the design of preventive strategies such as personal protective equipment.
Project description:The major focus of Dr. Argueso's research is to characterize the carbohydrate portion of the different mucins expressed by the ocular surface epithelia as well as the enzymes involved with their synthesis, and to determine whether the alteration of mucin glycosylation is associated with ocular surface disease. Highly glycosylated mucins on the ocular surface (cornea and conjunctiva) are the first line of defense of the eye against injury and infection. Changes in O-glycosylation of mucins may cause ocular surface disorders, such as dry eye. Gene expression patterns in the conjunctival epithelium of three normal subjects were analyzed. The three subjects have the same ABO-blood-group. For each donor, conjunctival cells were obtained by impression cytology. Conjunctival impression cytology was performed on each eye two times with a one-week interval. Conjunctival cells obtained from each individual were pooled and the RNA isolated. All three samples were hybridized to the custom designed CFG GLYCOv2 glycogene array.
Project description:Here we identify halofuginone, a Prolyl-tRNA Synthetase (PRS) inhibitors as a potent inhibitors of SARS-CoV-2 cellular entry and viral replication. To infect the host cell, the SARS-CoV-2 spike protein interacts with cell surface heparan sulfate (HS) and angiotensin-converting enzyme 2 (ACE2) through its Receptor Binding Domain. Removal of cell surface HS or blockade of HS biosynthesis represents a promising clinical target for treatment of SARS-CoV-2. In vitro studies confirm that halofuginone and PRS inhibitors prevent HS biosynthesis and thereby HS cell surface presentation and Spike protein binding. Halofuginone also suppresses authentic SARS-CoV-2 infection by inhibiting PRS activity, which decreases the translation efficiency of proline-rich HS biosynthetic enzymes and essential SARS-CoV-2 proteins after infection. Thus, halofuginone inhibits SARS-CoV-2 at both attachment and post-entry steps and blocks SARS-CoV-2 infection of human lung airway epithelial cells at low nanomolar concentrations. These findings support the use of halofuginone, an orally bioavailable anti-fibrotic and anti-inflammatory compound with encouraging clinical phase 1 safety data, as an antiviral drug to prevent SARS-CoV-2 infection.
Project description:Here we identify halofuginone, a Prolyl-tRNA Synthetase (PRS) inhibitors as a potent inhibitors of SARS-CoV-2 cellular entry and viral replication. To infect the host cell, the SARS-CoV-2 spike protein interacts with cell surface heparan sulfate (HS) and angiotensin-converting enzyme 2 (ACE2) through its Receptor Binding Domain. Removal of cell surface HS or blockade of HS biosynthesis represents a promising clinical target for treatment of SARS-CoV-2. In vitro studies confirm that halofuginone and PRS inhibitors prevent HS biosynthesis and thereby HS cell surface presentation and Spike protein binding. Halofuginone also suppresses authentic SARS-CoV-2 infection by inhibiting PRS activity, which decreases the translation efficiency of proline-rich HS biosynthetic enzymes and essential SARS-CoV-2 proteins after infection (data not provided here). Thus, halofuginone inhibits SARS-CoV-2 at both attachment and post-entry steps and blocks SARS-CoV-2 infection of human lung airway epithelial cells at low nanomolar concentrations. These findings support the use of halofuginone, an orally bioavailable anti-fibrotic and anti-inflammatory compound with encouraging clinical phase 1 safety data, as an antiviral drug to prevent SARS-CoV-2 infection.
Project description:Here we identify halofuginone, a Prolyl-tRNA Synthetase (PRS) inhibitors as a potent inhibitors of SARS-CoV-2 cellular entry and viral replication. To infect the host cell, the SARS-CoV-2 spike protein interacts with cell surface heparan sulfate (HS) and angiotensin-converting enzyme 2 (ACE2) through its Receptor Binding Domain. Removal of cell surface HS or blockade of HS biosynthesis represents a promising clinical target for treatment of SARS-CoV-2. In vitro studies confirm that halofuginone and PRS inhibitors prevent HS biosynthesis and thereby HS cell surface presentation and Spike protein binding. Halofuginone also suppresses authentic SARS-CoV-2 infection by inhibiting PRS activity, which decreases the translation efficiency of proline-rich HS biosynthetic enzymes and essential SARS-CoV-2 proteins after infection (data not provided here). Thus, halofuginone inhibits SARS-CoV-2 at both attachment and post-entry steps and blocks SARS-CoV-2 infection of human lung airway epithelial cells at low nanomolar concentrations. These findings support the use of halofuginone, an orally bioavailable anti-fibrotic and anti-inflammatory compound with encouraging clinical phase 1 safety data, as an antiviral drug to prevent SARS-CoV-2 infection.
Project description:Goblet cell numbers decrease within the conjunctival epithelium in drying and cicatrizing ocular surface diseases. Factors regulating goblet cell differentiation in conjunctival epithelium are unknown. Recent data indicate that the transcription factor SAM-pointed domain epithelial-specific transcription factor (Spdef) is essential for goblet cell differentiation in tracheobronchial and gastrointestinal epithelium of mice. Using Spdef -/- mice, we determined that Spdef is required for conjunctival goblet cell differentiation and that Spdef -/- mice, which lack conjunctival goblet cells, have significantly increased corneal surface fluorescein staining and tear volume, a phenotype consistent with dry eye. Microarray analysis of conjunctival epithelium in Spdef -/- mice identified 43 signficantly upregulated genes and 110 signficantly downregulated genes in the conjunctival epithelium of Spdef -/- mice compared to that of Spdef +/+ control mice (3 fold change, p<0.01). Downregulated genes of particular interested included goblet cell-specific genes (Muc5ac, Tff1, Gcnt3). Upregulated genes included epithelial cell differentiation/keratinization genes (Sprr2h, Tgm1) and pro-inflammatory genes (Il1-α, Il-1β, Tnf-α), all of which are upregulated in dry eye. Interestingly, four Wnt pathway genes were downregulated. Conjunctival epithelium of Spdef +/+ and Spdef -/- mice was collected by laser capture microdissection for RNA extraction and hybridization on Affymetrix microarrays to determine if gene expression patterns in the conjunctival epithelium of Spdef -/- mice is altered compared to that of Spdef +/+ mice.
Project description:Goblet cell numbers decrease within the conjunctival epithelium in drying and cicatrizing ocular surface diseases. Factors regulating goblet cell differentiation in conjunctival epithelium are unknown. Recent data indicate that the transcription factor SAM-pointed domain epithelial-specific transcription factor (Spdef) is essential for goblet cell differentiation in tracheobronchial and gastrointestinal epithelium of mice. Using Spdef -/- mice, we determined that Spdef is required for conjunctival goblet cell differentiation and that Spdef -/- mice, which lack conjunctival goblet cells, have significantly increased corneal surface fluorescein staining and tear volume, a phenotype consistent with dry eye. Microarray analysis of conjunctival epithelium in Spdef -/- mice identified 43 signficantly upregulated genes and 110 signficantly downregulated genes in the conjunctival epithelium of Spdef -/- mice compared to that of Spdef +/+ control mice (3 fold change, p<0.01). Downregulated genes of particular interested included goblet cell-specific genes (Muc5ac, Tff1, Gcnt3). Upregulated genes included epithelial cell differentiation/keratinization genes (Sprr2h, Tgm1) and pro-inflammatory genes (Il1-α, Il-1β, Tnf-α), all of which are upregulated in dry eye. Interestingly, four Wnt pathway genes were downregulated.
Project description:Ancestral SARS coronavirus-2 (SARS-CoV-2) and variants of concern (VOC) caused a global pandemic with a spectrum of disease variation linked to immune dysfunction. The mechanistic underpinnings of variation related to lung epithelium are relatively understudied. Here, we biobanked lung organoids by preserving stem cell function. We optimized viral infection with H1N1 swine flu and next comprehensively characterized epithelial responses to SARS-CoV-2 infection in phenotypically stable lung organoids from twenty different subjects. We discovered Tetraspanin 8 (TSPAN8) as a novel mediator of SARS-CoV-2-infection. TSPAN8 facilitates SARS-CoV-2 infection rates but does not via enhanced ACE-2-mediated entry. In head-to-head comparisons with Ancestral SARS-CoV-2, Delta- and Omicron- VOC displayed lower overall infection rates of organoids but triggered increased epithelial interferon responses. All variants shared highest tropism for ciliated- and goblet- cells. ACE2- and TSPAN8- expression are universal features of infected cells. TSPAN8-blocking antibodies diminish SARS-CoV-2 infection and may spur novel avenues for COVID-19 therapy.
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:Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, continues to spread around the world with serious cases and deaths. It has also been suggested that different genetic variants in the human genome affect both the susceptibility to infection and severity of disease in COVID-19 patients. Angiotensin-converting enzyme 2 (ACE2) has been identified as a cell surface receptor for SARS-CoV and SARS-CoV-2 entry into cells. The construction of an experimental model system using human iPS cells would enable further studies of the association between viral characteristics and genetic variants. Airway and alveolar epithelial cells are cell types of the lung that express high levels of ACE2 and are suitable for in vitro infection experiments. Here, we show that human iPS cell-derived airway and alveolar epithelial cells are highly susceptible to viral infection of SARS-CoV-2. Using gene knockout with CRISPR-Cas9 in human iPS cells we demonstrate that ACE2 plays an essential role in the airway and alveolar epithelial cell entry of SARS-CoV-2 in vitro. Replication of SARS-CoV-2 was strongly suppressed in ACE2 knockout (KO) lung cells. Our model system based on human iPS cell-derived lung cells may be applied to understand the molecular biology regulating viral respiratory infection leading to potential therapeutic developments for COVID-19 and the prevention of future pandemics.
Project description:Human airway epithelia (HAE) undergo inflammation-induced remodeling in chronic lung diseases such as asthma and chronic bronchitis. The role of type 2 inflammation-induced epithelial remodeling in SARS-CoV-2 infection and the course of COVID-19 is unclear, moreover, there is discrepancy in the literature regarding the potential benefit of treatments that modulate type 2 inflammation. We investigated the role of IL-13-induced inflammation on SARS-CoV-2 binding/entry, replication, and host response in primary HAE cells in vitro and in a model of mouse-adapted SARS-CoV-2 in vivo. IL-13 protected airway epithelial cells from SARS-CoV-2 infection in vitro by decreasing the abundance of ACE2- expressing ciliated cells rather than by neutralization in the airway surface liquid or by interferon-mediated antiviral effects. In contrast, IL-13 worsened the severity of disease in mice in vivo; the effects were mediated by eicosanoid signaling and were abolished in mice deficient in the phospholipase A2 enzyme PLA2G2D. We conclude that IL-13-induced inflammation affects multiple steps of SARS-CoV-2-induced disease pathogenesis. Whereas IL-13-induced inflammation may be protective against initial infection at the airway epithelium, it enhances disease severity once infection progresses in vivo; blockade of IL-13 and/or eicosanoid signaling may be protective against progression to severe lung disease.