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1.
Int J Mol Sci ; 22(6)2021 Mar 20.
Article in English | MEDLINE | ID: covidwho-1143521

ABSTRACT

SARS-CoV-2 infection can cause cytokine storm and may overshoot immunity in humans; however, it remains to be determined whether virus-induced soluble mediators from infected cells are carried by exosomes as vehicles to distant organs and cause tissue damage in COVID-19 patients. We took an unbiased proteomic approach for analyses of exosomes isolated from plasma of healthy volunteers and COVID-19 patients. Our results revealed that tenascin-C (TNC) and fibrinogen-ß (FGB) are highly abundant in exosomes from COVID-19 patients' plasma compared with that of healthy normal controls. Since TNC and FGB stimulate pro-inflammatory cytokines via the Nuclear factor-κB (NF-κB) pathway, we examined the status of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and C-C motif chemokine ligand 5 (CCL5) expression upon exposure of hepatocytes to exosomes from COVID-19 patients and observed significant increase compared with that from healthy subjects. Together, our results demonstrate that TNC and FGB are transported through plasma exosomes and potentially trigger pro-inflammatory cytokine signaling in cells of distant organ.


Subject(s)
COVID-19/blood , Exosomes/chemistry , Exosomes/genetics , Fibrinogen/metabolism , Inflammation/metabolism , Tenascin/metabolism , Aged , COVID-19/complications , Cell Line , Chemokine CCL5/metabolism , Exosomes/metabolism , Exosomes/ultrastructure , Female , Hepatocytes/metabolism , Humans , Inflammation/etiology , Interleukin-6/metabolism , Male , Mass Spectrometry , Microscopy, Electron, Transmission , Middle Aged , NF-kappa B/metabolism , Protein Interaction Maps , Proteome/metabolism , Tumor Necrosis Factor-alpha/metabolism
2.
PLoS Pathog ; 16(12): e1009128, 2020 12.
Article in English | MEDLINE | ID: covidwho-992722

ABSTRACT

Cytokine storm is suggested as one of the major pathological characteristics of SARS-CoV-2 infection, although the mechanism for initiation of a hyper-inflammatory response, and multi-organ damage from viral infection is poorly understood. In this virus-cell interaction study, we observed that SARS-CoV-2 infection or viral spike protein expression alone inhibited angiotensin converting enzyme-2 (ACE2) receptor protein expression. The spike protein promoted an angiotensin II type 1 receptor (AT1) mediated signaling cascade, induced the transcriptional regulatory molecules NF-κB and AP-1/c-Fos via MAPK activation, and increased IL-6 release. SARS-CoV-2 infected patient sera contained elevated levels of IL-6 and soluble IL-6R. Up-regulated AT1 receptor signaling also influenced the release of extracellular soluble IL-6R by the induction of the ADAM-17 protease. Use of the AT1 receptor antagonist, Candesartan cilexetil, resulted in down-regulation of IL-6/soluble IL-6R release in spike expressing cells. Phosphorylation of STAT3 at the Tyr705 residue plays an important role as a transcriptional inducer for SOCS3 and MCP-1 expression. Further study indicated that inhibition of STAT3 Tyr705 phosphorylation in SARS-CoV-2 infected and viral spike protein expressing epithelial cells did not induce SOCS3 and MCP-1 expression. Introduction of culture supernatant from SARS-CoV-2 spike expressing cells on a model human liver endothelial Cell line (TMNK-1), where transmembrane IL-6R is poorly expressed, resulted in the induction of STAT3 Tyr705 phosphorylation as well as MCP-1 expression. In conclusion, our results indicated that the presence of SARS-CoV-2 spike protein in epithelial cells promotes IL-6 trans-signaling by activation of the AT1 axis to initiate coordination of a hyper-inflammatory response.


Subject(s)
COVID-19/immunology , Interleukin-6/immunology , Receptors, Angiotensin/metabolism , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , COVID-19/metabolism , Cytokine Release Syndrome/immunology , Cytokine Release Syndrome/metabolism , Cytokine Release Syndrome/virology , Epithelial Cells/immunology , Epithelial Cells/metabolism , Epithelial Cells/virology , Humans , Interleukin-6/metabolism , Respiratory Mucosa/immunology , Respiratory Mucosa/metabolism , Respiratory Mucosa/virology , SARS-CoV-2/metabolism , Signal Transduction/physiology , Transcriptional Activation
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