Herpes simplex virus type 1 dysregulates anti-fungal defenses preventing monocyte activation and downregulating toll-like receptor-2

Microbiol Immunol. 2008 Dec;52(12):575-84. doi: 10.1111/j.1348-0421.2008.00074.x.

Abstract

We investigated the interplay occurring between pathogens in the course of dual infections, using an in vitro model in which the THP-1 monocytic cell line is first infected with HSV-1 and then exposed to Ca or Cn. These three pathogens share some pathogenic features: they cause opportunistic infections, target macrophages and are neurotropic. Here, we show that HSV-1-infected THP-1 cells exhibited augmented phagocytosis against the two opportunistic fungi but reduced capability to counteract fungal infection: the better ingestion by monocytes was followed by facilitated fungal survival and replication. Reduced IL-12 production was also observed. Cytofluorimetric analysis showed that HSV-1-infected monocytes exhibit: (i) downregulated TLR-2 and TLR-4, critical structures in fungal recognition; (ii) reduced expression of CD38 and CD69, known to be important markers of monocyte activation; and (iii) enhanced expression of apoptosis and necrosis markers, in the absence of altered cell proliferation. Overall, these findings imply that HSV-1 infection prevents monocyte activation, thus leading to a significant dysfunction of the monocyte-mediated anti-Candida response; HSV-1 induced apoptosis and necrosis of monocytes further contribute to this impairment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis
  • Cell Line, Tumor
  • Cryptococcus / immunology*
  • Down-Regulation*
  • Herpes Simplex / immunology*
  • Herpes Simplex / microbiology
  • Herpes Simplex / virology
  • Herpesvirus 1, Human / immunology*
  • Humans
  • Interleukin-12 / genetics
  • Interleukin-12 / immunology
  • Monocytes / immunology*
  • Monocytes / microbiology
  • Monocytes / virology
  • Phagocytosis
  • Toll-Like Receptor 2 / genetics
  • Toll-Like Receptor 2 / immunology*
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / immunology

Substances

  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Interleukin-12