Toll-like receptor (TLR) 2 and TLR9 expressed in trigeminal ganglia are critical to viral control during herpes simplex virus 1 infection

Am J Pathol. 2010 Nov;177(5):2433-45. doi: 10.2353/ajpath.2010.100121. Epub 2010 Sep 23.

Abstract

Herpes simplex virus 1 (HSV-1) is a neurotropic DNA virus that is responsible for several clinical manifestations in humans, including encephalitis. HSV-1 triggers toll-like receptors (TLRs), which elicit cytokine production. Viral multiplication and cytokine expression in C57BL/6 wild-type (WT) mice infected with HSV-1 were evaluated. Virus was found in the trigeminal ganglia (TG), but not in the brains of animals without signs of encephalitis, between 2 and 6 days postinfection (d.p.i.). Cytokine expression in the TG peaked at 5 d.p.i. TLR9-/- and TLR2/9-/- mice were more susceptible to the virus, with 60% and 100% mortality, respectively, as opposed to 10% in the WT and TLR2-/- mice. Increased levels of both CXCL10/IP-10 and CCL2/MCP-1, as well as reduced levels of interferon-γ and interleukin 1-β transcripts, measured in both the TG and brains at 5 d.p.i., and the presence of virus in the brain were correlated with total mortality in TLR2/9-/- mice. Cytokine alterations in TLR2/9-/- mice coincided with histopathological changes in their brains, which did not occur in WT and TLR2-/- mice and occurred only slightly in TLR9-/- mouse brain. Increased cellularity, macrophages, CD8 T cells producing interferon-γ, and expression levels of TLR2 and TLR9 were detected in the TG of WT-infected mice. We hypothesize that HSV-1 infection is controlled by TLR-dependent immune responses in the TG, which prevent HSV-1 encephalitis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain / immunology
  • Brain / pathology
  • Brain / virology
  • Cell Line
  • Chemokines / blood
  • Chemokines / immunology
  • Cytokines / blood
  • Cytokines / immunology
  • Herpes Simplex / immunology*
  • Herpes Simplex / virology*
  • Herpesvirus 1, Human / immunology*
  • Herpesvirus 1, Human / pathogenicity
  • Humans
  • Interleukin-12 Subunit p40 / immunology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Toll-Like Receptor 2 / genetics
  • Toll-Like Receptor 2 / immunology*
  • Toll-Like Receptor 9 / genetics
  • Toll-Like Receptor 9 / immunology*
  • Trigeminal Ganglion / immunology*
  • Trigeminal Ganglion / virology*
  • Tumor Necrosis Factor-alpha / immunology

Substances

  • Chemokines
  • Cytokines
  • Interleukin-12 Subunit p40
  • Toll-Like Receptor 2
  • Toll-Like Receptor 9
  • Tumor Necrosis Factor-alpha