SARS-CoV-2 is the novel coronavirus responsible for the current COVID-19 pandemic. Severe complications are observed only in a small proportion of infected patients but the cellular mechanisms underlying this progression are still unknown. Comprehensive flow cytometry of whole blood samples from 54 COVID-19 patients reveals a dramatic increase in the number of immature neutrophils. This increase strongly correlates with disease severity and is associated with elevated IL-6 and IP-10 levels, two key players in the cytokine storm. The most pronounced decrease in cell counts is observed for CD8 T-cells and VD2 γδ T-cells, which both exhibit increased differentiation and activation. ROC analysis reveals that the count ratio of immature neutrophils to VD2 (or CD8) T-cells predicts pneumonia onset (0.9071) as well as hypoxia onset (0.8908) with high sensitivity and specificity. It would thus be a useful prognostic marker for preventive patient management and improved healthcare resource management.

The novel coronavirus SARS-CoV-2 is the causative agent of Coronavirus Disease 2019 (COVID-19), a global healthcare and economic catastrophe. Understanding of the host immune response to SARS-CoV-2 is still in its infancy. A 382-nt deletion strain lacking ORF8 (Δ382 herein) was isolated in Singapore in March 2020. Infection with Δ382 was associated with less severe disease in patients, compared to infection with wild-type SARS-CoV-2. Here, we established Nasal Epithelial cells (NECs) differentiated from healthy nasal-tissue derived stem cells as a suitable model for the ex-vivo study of SARS-CoV-2 mediated pathogenesis. Infection of NECs with either SARS-CoV-2 or Δ382 resulted in virus particles released exclusively from the apical side, with similar replication kinetics. Screening of a panel of 49 cytokines for basolateral secretion from infected NECs identified CXCL10 as the only cytokine significantly induced upon infection, at comparable levels in both wild-type and Δ382 infected cells. Transcriptome analysis revealed the temporal up-regulation of distinct gene subsets during infection, with anti-viral signaling pathways only detected at late time-points (72 hours post-infection, hpi). This immune response to SARS-CoV-2 was significantly attenuated when compared to infection with an influenza strain, H3N2, which elicited an inflammatory response within 8 hpi, and a greater magnitude of anti-viral gene up-regulation at late time-points. Remarkably, Δ382 induced a host transcriptional response nearly identical to that of wild-type SARS-CoV-2 at every post-infection time-point examined. In accordance with previous results, Δ382 infected cells showed an absence of transcripts mapping to ORF8, and conserved expression of other SARS-CoV-2 genes. Our findings shed light on the airway epithelial response to SARS-CoV-2 infection, and demonstrate a non-essential role for ORF8 in modulating host gene expression and cytokine production from infected cells.

Introduction: The pathways underlying chronic rhinosinusitis with nasal polyps (CRSwNP) are unclear. We conducted genome-wide gene expression analysis to determine pathways and candidate gene sets associated with CRSwNP.Methods: We performed whole-transcriptome RNA sequencing on 42 polyp (CRSwNP-NP) and 33 paired nonpolyp inferior turbinate (CRSwNP-IT) tissues from patients with CRSwNP and 28 inferior turbinate samples from non-CRS controls (CS-IT). We analysed the differentially expressed genes (DEGs) and the gene sets that were enriched in functional pathways.Results: Principal component-informed analysis revealed cilium function and immune regulation as the two main Gene Ontology (GO) categories differentiating CRSwNP patients from controls. We detected 6182 and 1592 DEGs between CRSwNP-NPversusCS-IT and between CRSwNP-NPversusCRSwNP-IT tissues, respectively. Atopy status did not have a major impact on gene expression in various tissues. GO analysis on these DEGs implicated extracellular matrix (ECM) disassembly,O-glycan processing, angiogenesis and host viral response in CRSwNP pathogenesis. Ingenuity Pathway Analysis identified significant enrichment of type 1 interferon signalling and axonal guidance canonical pathways, angiogenesis, and collagen and fibrotic changes in CRSwNP (CRSwNP-NP and CRSwNP-IT) tissues compared with CS-IT. Finally, gene set enrichment analysis implicated sets of genes co-regulated in processes associated with inflammatory response and aberrant cell differentiation in polyp formation.Conclusions: Gene signatures involved in defective host defences (including cilia dysfunction and immune dysregulation), inflammation and abnormal metabolism of ECM are implicated in CRSwNP. Functional validation of these gene expression patterns will open opportunities for CRSwNP therapeutic interventions such as biologics and immunomodulators.

Extracellular ATP is a pro-inflammatory molecule released by damaged cells. Regulatory T cells (Treg) can suppress inflammation by hydrolysing this molecule via ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD1), also termed as CD39. Multiple studies have reported differences in CD39+ Treg percentages in diseases such as multiple sclerosis, Hepatitis B and HIV-1. In addition, CD39 polymorphisms have been implicated in immune-phenotypes such as susceptibility to inflammatory bowel disease and AIDS progression. However none of the studies published so far has linked disease-associated variants with differences in CD39 Treg surface expression. This study aims at identifying variants affecting CD39 expression on Treg and at evaluating their association with allergic rhinitis, a disease characterized by a strong Treg involvement.