T cells detect intracellular DNA but fail to induce type I IFN responses: implications for restriction of HIV replication

PLoS One. 2014 Jan 3;9(1):e84513. doi: 10.1371/journal.pone.0084513. eCollection 2014.

Abstract

HIV infects key cell types of the immune system, most notably macrophages and CD4+ T cells. Whereas macrophages represent an important viral reservoir, activated CD4+ T cells are the most permissive cell types supporting high levels of viral replication. In recent years, it has been appreciated that the innate immune system plays an important role in controlling HIV replication, e.g. via interferon (IFN)-inducible restriction factors. Moreover, innate immune responses are involved in driving chronic immune activation and the pathogenesis of progressive immunodeficiency. Several pattern recognition receptors detecting HIV have been reported, including Toll-like receptor 7 and Retinoic-inducible gene-I, which detects viral RNA. Here we report that human primary T cells fail to induce strong IFN responses, despite the fact that this cell type does express key molecules involved in DNA signaling pathways. We demonstrate that the DNA sensor IFI16 migrates to sites of foreign DNA localization in the cytoplasm and recruits the signaling molecules stimulator of IFN genes and Tank-binding kinase, but this does not result in expression of IFN and IFN-stimulated genes. Importantly, we show that cytosolic DNA fails to affect HIV replication. However, exogenous treatment of activated T cells with type I IFN has the capacity to induce expression of IFN-stimulated genes and suppress HIV replication. Our data suggest the existence of an impaired DNA signaling machinery in T cells, which may prevent this cell type from activating cell-autonomous anti-HIV responses. This phenomenon could contribute to the high permissiveness of CD4+ T cells for HIV-1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis
  • Biological Transport
  • CD4-Positive T-Lymphocytes / immunology
  • CD4-Positive T-Lymphocytes / metabolism
  • Cytokines / biosynthesis
  • Cytosol / metabolism
  • DNA / immunology*
  • DNA / metabolism
  • HIV Infections / immunology*
  • HIV Infections / virology*
  • HIV-1 / immunology*
  • Humans
  • Inflammation Mediators / metabolism
  • Interferon Type I / immunology*
  • Interferon Type I / metabolism
  • Interleukin-2 / pharmacology
  • Leukocytes, Mononuclear / drug effects
  • Leukocytes, Mononuclear / immunology
  • Leukocytes, Mononuclear / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Protein Binding
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / virology*
  • Transfection
  • Virus Replication / immunology

Substances

  • Cytokines
  • Inflammation Mediators
  • Interferon Type I
  • Interleukin-2
  • Membrane Proteins
  • STING1 protein, human
  • DNA
  • Protein Serine-Threonine Kinases
  • TBK1 protein, human

Grants and funding

This work was supported by the Danish Medical Research Council (grant numbers 09-066031 (THM), 12-124330 (SRP), and 10-081986 (MRJ)). In addition, the work was supported by Kong Christian IX og Dronning Louises Jubilæumslegat, Aase og Ejnar Danielsens Fond and The Foundation for the Advancement of Medical Sciences. RKB is recipient of a PhD fellowship from the Faculty of Health Sciences, Aarhus University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.