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The coronavirus disease 2019 (COVID‐19) pandemic is an ongoing global public health crisis. The causative agent, the SARS‐CoV‐2 virus, enters host cells via molecular interactions between the viral spike protein and the host cell ACE2 surface protein. The SARS‐CoV‐2 spike protein is extensively decorated with up to 66 N‐linked glycans. Glycosylation of viral proteins is known to function in immune evasion strategies but may also function in the molecular events of viral entry into host cells. Here, we show that N‐glycosylation at Asn331 and Asn343 of SARS‐CoV‐2 spike protein is required for it to bind to ACE2 and for the entry of pseudovirus harboring the SARS‐CoV‐2 spike protein into cells. Interestingly, high‐content glycan binding screening data have shown that N‐glycosylation of Asn331 and Asn343 of the RBD is important for binding to the specific glycan molecule G4GN (Galβ−1,4 GlcNAc), which is critical for spike‐RBD‐ACE2 binding. Furthermore, IL‐6 was identified through antibody array analysis of conditioned media of the corresponding pseudovirus assay. Mutation of N‐glycosylation of Asn331 and Asn343 sites of the spike receptor‐binding domain (RBD) significantly reduced the transcriptional upregulation of pro‐inflammatory signaling molecule IL‐6. In addition, IL‐6 levels correlated with spike protein levels in COVID‐19 patients' serum. These findings establish the importance of RBD glycosylation in SARS‐CoV‐2 pathogenesis, which can be exploited for the development of novel therapeutics for COVID‐19. [ABSTRACT FROM AUTHOR]

Cytokine release syndromes represent a severe turn in certain disease states, which may be caused by several infections, including those with the virus SARS‐CoV‐2. This inefficient, even harmful, immune response has been associated with a broad release of chemokines. Although a cellular (type I) immune reaction is efficacious against viral infections, we noted a type I deficit in the cytokine patterns produced by cytokine storms of all reported etiologies. Agents including lipopolysaccharide (LPS, bacterial), anti‐CD3 (antibody) and a version of the prominent SARS‐CoV‐2 viral surface molecule, Spike Glycoprotein, were individually sufficient to induce IL‐6 and multiple chemokines in mice. They failed to upregulate the TH1 inducer cytokine Osteopontin, and the pathophysiologic triggers actually suppressed the PMA‐induced Osteopontin secretion from monocytic cells. Osteopontin administration partially reversed the chemokine elevation, more effectively so in a mouse strain with TH1 bias. Corroboration was obtained from the inverse correlation in the levels of IL‐6 and Osteopontin in plasma samples from acute COVID‐19 patients. We hypothesize that the inhibition of Osteopontin by SARS‐CoV‐2 Spike Glycoprotein or LPS represents an immune evasion mechanism employed by the pathogens of origin. The ensuing dysfunctional inflammatory response promotes a vicious cycle of amplification, resulting in a cytokine storm. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to simultaneously and quantitatively assess the expression levels of 20 periodontal disease-related proteins in gingival crevicular fluid (GCF) from normal controls (NOR) and severe periodontitis (SP) patients with an antibody array.Methods: Antibodies against 20 periodontal disease-related proteins were spotted onto a glass slide to create a periodontal disease antibody array (PDD). The array was then incubated with GCF samples collected from 25 NOR and 25 SP patients. Differentially expressed proteins between NOR and SP patients were then used to build receiver operator characteristic (ROC) curves and compare five classification models, including support vector machine, random forest, k nearest neighbor, linear discriminant analysis, and Classification and Regression Trees.Results: Seven proteins (C-reactive protein, interleukin [IL]-1α, interleukin-1β, interleukin-8, matrix metalloproteinase-13, osteoprotegerin, and osteoactivin) were significantly upregulated in SP patients compared with NOR, while receptor activator of nuclear factor-kappa was significantly downregulated. The highest diagnostic accuracy using a ROC curve was observed for IL-1β with an area under the curve of 0.984. Five of the proteins (IL-1β, IL-8, MMP-13, osteoprotegerin, and osteoactivin) were identified as important features for classification. Linear discriminant analysis had the highest classification accuracy across the five classification models that were tested.Conclusion: This study highlights the potential of antibody arrays to diagnose periodontal disease. [ABSTRACT FROM AUTHOR]