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Front Immunol ; 12: 743890, 2021.
Article in English | MEDLINE | ID: covidwho-1581344


Background: Both anti-viral and anti-inflammatory bronchial effects are warranted to treat viral infections in asthma. We sought to investigate if imiquimod, a TLR7 agonist, exhibits such dual actions in ex vivo cultured human bronchial epithelial cells (HBECs), targets for SARS-CoV-2 infectivity. Objective: To investigate bronchial epithelial effects of imiquimod of potential importance for anti-viral treatment in asthmatic patients. Methods: Effects of imiquimod alone were examined in HBECs from healthy (N=4) and asthmatic (N=18) donors. Mimicking SARS-CoV-2 infection, HBECs were stimulated with poly(I:C), a dsRNA analogue, or SARS-CoV-2 spike-protein 1 (SP1; receptor binding) with and without imiquimod treatment. Expression of SARS-CoV-2 receptor (ACE2), pro-inflammatory and anti-viral cytokines were analyzed by RT-qPCR, multiplex ELISA, western blot, and Nanostring and proteomic analyses. Results: Imiquimod reduced ACE2 expression at baseline and after poly(I:C) stimulation. Imiquimod also reduced poly(I:C)-induced pro-inflammatory cytokines including IL-1ß, IL-6, IL-8, and IL-33. Furthermore, imiquimod increased IFN-ß expression, an effect potentiated in presence of poly(I:C) or SP1. Multiplex mRNA analysis verified enrichment in type-I IFN signaling concomitant with suppression of cytokine signaling pathways induced by imiquimod in presence of poly(I:C). Exploratory proteomic analyses revealed potentially protective effects of imiquimod on infections. Conclusion: Imiquimod triggers viral resistance mechanisms in HBECs by decreasing ACE2 and increasing IFN-ß expression. Additionally, imiquimod improves viral infection tolerance by reducing viral stimulus-induced epithelial cytokines involved in severe COVID-19 infection. Our imiquimod data highlight feasibility of producing pluripotent drugs potentially suited for anti-viral treatment in asthmatic subjects.

Angiotensin-Converting Enzyme 2/metabolism , Asthma , COVID-19 , Imiquimod/pharmacology , Interferon-beta/drug effects , Respiratory Mucosa/drug effects , Adjuvants, Immunologic/pharmacology , Adult , Aged , Bronchi/drug effects , Bronchi/immunology , Bronchi/virology , Cells, Cultured , Female , Humans , Interferon-beta/immunology , Male , Middle Aged , Respiratory Mucosa/metabolism , Respiratory Mucosa/virology , SARS-CoV-2
J Mol Cell Biol ; 12(12): 916-932, 2020 10 12.
Article in English | MEDLINE | ID: covidwho-968717


There is a link between high lipopolysaccharide (LPS) levels in the blood and the metabolic syndrome, and metabolic syndrome predisposes patients to severe COVID-19. Here, we define an interaction between SARS-CoV-2 spike (S) protein and LPS, leading to aggravated inflammation in vitro and in vivo. Native gel electrophoresis demonstrated that SARS-CoV-2 S protein binds to LPS. Microscale thermophoresis yielded a KD of ∼47 nM for the interaction. Computational modeling and all-atom molecular dynamics simulations further substantiated the experimental results, identifying a main LPS-binding site in SARS-CoV-2 S protein. S protein, when combined with low levels of LPS, boosted nuclear factor-kappa B (NF-κB) activation in monocytic THP-1 cells and cytokine responses in human blood and peripheral blood mononuclear cells, respectively. The in vitro inflammatory response was further validated by employing NF-κB reporter mice and in vivo bioimaging. Dynamic light scattering, transmission electron microscopy, and LPS-FITC analyses demonstrated that S protein modulated the aggregation state of LPS, providing a molecular explanation for the observed boosting effect. Taken together, our results provide an interesting molecular link between excessive inflammation during infection with SARS-CoV-2 and comorbidities involving increased levels of bacterial endotoxins.

COVID-19/complications , Inflammation/etiology , Lipopolysaccharides/metabolism , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/metabolism , Animals , Binding Sites , COVID-19/immunology , COVID-19/virology , Cytokine Release Syndrome/etiology , Cytokine Release Syndrome/immunology , Disease Models, Animal , Gram-Negative Bacterial Infections/complications , Gram-Negative Bacterial Infections/immunology , Humans , In Vitro Techniques , Lipid A/chemistry , Lipid A/immunology , Lipid A/metabolism , Lipopolysaccharides/chemistry , Lipopolysaccharides/immunology , Mice , Mice, Inbred BALB C , Mice, Transgenic , Models, Immunological , Models, Molecular , Molecular Docking Simulation , Protein Binding , Protein Interaction Domains and Motifs , Respiratory Distress Syndrome/etiology , Risk Factors , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology