SARS-CoV-2 spike protein promotes IL-6 trans-signaling by activation of angiotensin II receptor signaling in epithelial cells

PLoS Pathog. 2020 Dec 7;16(12):e1009128. doi: 10.1371/journal.ppat.1009128. eCollection 2020 Dec.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • COVID-19 / 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 / immunology*
  • Interleukin-6 / metabolism
  • Receptors, Angiotensin / metabolism*
  • Respiratory Mucosa / immunology
  • Respiratory Mucosa / metabolism
  • Respiratory Mucosa / virology
  • SARS-CoV-2 / immunology*
  • SARS-CoV-2 / metabolism
  • Signal Transduction / physiology
  • Spike Glycoprotein, Coronavirus / immunology*
  • Transcriptional Activation

Substances

  • IL6 protein, human
  • Interleukin-6
  • Receptors, Angiotensin
  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2

Grant support

Exclusive internal funding was provided from Saint Louis University to RR. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.