Roles of TLR3 and RIG-I in mediating the inflammatory response in mouse microglia following Japanese encephalitis virus infection

J Immunol Res. 2014:2014:787023. doi: 10.1155/2014/787023. Epub 2014 Jul 3.

Abstract

Japanese encephalitis virus (JEV) infection can cause central nervous system disease with irreversible neurological damage in humans and animals. Evidence suggests that overactivation of microglia leads to greatly increased neuronal damage during JEV infection. However, the mechanism by which JEV induces the activation of microglia remains unclear. Toll-like receptor 3 (TLR3) and retinoic acid-inducible gene I (RIG-I) can recognize double-stranded RNA, and their downstream signaling results in production of proinflammatory mediators. In this study, we investigated the roles of TLR3 and RIG-I in the inflammatory response caused by JEV infection in the mouse microglial cell line. JEV infection induced the expression of TLR3 and RIG-I and the activation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38MAPK). Knockdown of TLR3 and RIG-I attenuated activation of ERK, p38MAPK, activator protein 1 (AP-1), and nuclear factor κB (NF-κB). Secretion of TNF-α, IL-6, and CCL-2, which was induced by JEV, was reduced by TLR3 and RIG-I knockdown and inhibitors of phosphorylated ERK and p38MAPK. Furthermore, viral proliferation was increased following knockdown of TLR3 and RIG-I. Our findings suggest that the signaling pathways of TLR3 and RIG-I play important roles in the JEV-induced inflammatory response of microglia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Cells, Cultured
  • Cytokines / biosynthesis
  • Encephalitis Virus, Japanese / immunology*
  • Encephalitis, Japanese / genetics
  • Encephalitis, Japanese / immunology
  • Encephalitis, Japanese / metabolism
  • Enzyme Activation
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Gene Expression Regulation
  • Gene Knockdown Techniques
  • Inflammation Mediators / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Microglia / metabolism*
  • Microglia / virology*
  • NF-kappa B / metabolism
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Protein Kinase Inhibitors / pharmacology
  • Protein Transport
  • RNA Interference
  • Receptors, Cell Surface
  • Toll-Like Receptor 3 / genetics
  • Toll-Like Receptor 3 / metabolism*
  • Transcription Factor AP-1 / metabolism
  • Up-Regulation
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Cytokines
  • Inflammation Mediators
  • Membrane Proteins
  • NF-kappa B
  • Nerve Tissue Proteins
  • Protein Kinase Inhibitors
  • Receptors, Cell Surface
  • Robo3 protein, mouse
  • Toll-Like Receptor 3
  • Transcription Factor AP-1
  • Extracellular Signal-Regulated MAP Kinases
  • p38 Mitogen-Activated Protein Kinases