Silver Nanoparticles Impair Retinoic Acid-Inducible Gene I-Mediated Mitochondrial Antiviral Immunity by Blocking the Autophagic Flux in Lung Epithelial Cells

ACS Nano. 2018 Feb 27;12(2):1188-1202. doi: 10.1021/acsnano.7b06934. Epub 2018 Jan 30.


Silver nanoparticles (AgNPs) are microbicidal agents which could be potentially used as an alternative to antivirals to treat human infectious diseases, especially influenza virus infections where antivirals have generally proven unsuccessful. However, concerns about the use of AgNPs on humans arise from their potential toxicity, although mechanisms are not well-understood. We show here, in the context of an influenza virus infection of lung epithelial cells, that AgNPs down-regulated influenza induced CCL-5 and -IFN-β release (two cytokines important in antiviral immunity) through RIG-I inhibition, while enhancing IL-8 production, a cytokine important for mobilizing host antibacterial responses. AgNPs activity was independent of coating and was not observed with gold nanoparticles. Down-stream analysis indicated that AgNPs disorganized the mitochondrial network and prevented the antiviral IRF-7 transcription factor influx into the nucleus. Importantly, we showed that the modulation of RIG-I-IRF-7 pathway was concomitant with inhibition of either classical or alternative autophagy (ATG-5- and Rab-9 dependent, respectively), depending on the epithelial cell type used. Altogether, this demonstration of a AgNPs-mediated functional dichotomy (down-regulation of IFN-dependent antiviral responses and up-regulation of IL-8-dependent antibacterial responses) may have practical implications for their use in the clinic.

Keywords: CCL-5; autophagy; influenza; interferon; mitochondria; nanotoxicology; silver nanoparticles.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antiviral Agents / chemistry
  • Antiviral Agents / pharmacology*
  • Autophagy / drug effects
  • Cell Line, Tumor
  • Dogs
  • Epithelial Cells / drug effects*
  • Epithelial Cells / metabolism
  • Epithelial Cells / virology
  • Humans
  • Lung / drug effects*
  • Lung / metabolism
  • Lung / virology
  • Madin Darby Canine Kidney Cells / drug effects
  • Madin Darby Canine Kidney Cells / virology
  • Metal Nanoparticles / chemistry*
  • Microbial Sensitivity Tests
  • Mitochondria / drug effects*
  • Mitochondria / metabolism
  • Orthomyxoviridae / drug effects*
  • Silver / chemistry
  • Silver / pharmacology*
  • Tretinoin / chemistry
  • Tretinoin / pharmacology*


  • Antiviral Agents
  • Silver
  • Tretinoin