Exogenous IL-7 induces Fas-mediated human neuronal apoptosis: potential effects during human immunodeficiency virus type 1 infection

J Neurovirol. 2005 Aug;11(4):319-28. doi: 10.1080/13550280500187005.

Abstract

The use of exogenous cytokines is part of translational immune-antiretroviral approaches to induce immune reconstitution and possibly eliminate the persistence of human immunodeficiency virus type 1 (HIV-1) in virally suppressed infected individuals on highly active antiretroviral therapy (HAART). Recently, our laboratories demonstrated that interleukin-7 (IL-7) has significant efficiency in stimulating HIV-1 replication from proviral latency in CD4+ T lymphocytes of infected patients. The authors now investigated the possible role of IL-7 in HIV-1-associated dementia (HAD). The authors demonstrated that the IL-7 receptor is expressed on both human neurons (i.e., differentiated NT2 cells) and human astrocytes, with relatively higher mRNA levels in neurons. The translational protein levels of IL-7 receptor alpha were not proportional to those of the mRNA levels in these central nervous system (CNS)-based cell types. Exogenous IL-7 was observed to only slightly down-regulate IL-7 receptor alpha expression on both neurons and astrocytes, as assayed by Western blotting. Instead of promoting survival, surprisingly, exogenous IL-7 induced neuronal apoptosis, as detected by TUNEL assays. Furthermore, IL-7 augmented neuronal apoptosis induced by HIV-1 gp120. Human apoptosis genomic microarray analyses of IL-7-treated human neurons showed up-regulated expression of proapoptotic genes: protein kinases, caspase-10, FAST kinase, tumor necrosis factor (TNF) receptor, and BCL2-antagonist of cell death. These data suggest that IL-7 leads to neuronal apoptosis by a molecular mechanism(s) that occurs via Fas-mediated activation-induced cell death. These studies may therefore not only be key in evaluating the potential use of IL-7 in vivo as a therapeutic modality, but also suggest that IL-7, which is increased endogenously in HIV-1-infected individuals late in disease, may be involved in the neuronal apoptosis demonstrated during HAD.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Apoptosis / immunology*
  • Astrocytes / cytology
  • Astrocytes / immunology
  • Astrocytes / virology
  • Cells, Cultured
  • DNA-Binding Proteins / metabolism
  • Gene Expression / immunology
  • Genomics
  • HIV Envelope Protein gp120 / metabolism
  • HIV Infections / immunology*
  • HIV-1*
  • Humans
  • Interleukin-7 / genetics*
  • Milk Proteins / metabolism
  • Neurons / cytology
  • Neurons / immunology
  • Neurons / virology*
  • Oligonucleotide Array Sequence Analysis
  • RNA, Messenger / analysis
  • Receptors, Interleukin-7 / genetics
  • STAT5 Transcription Factor
  • Trans-Activators / metabolism
  • Virus Replication / immunology
  • fas Receptor / metabolism*

Substances

  • DNA-Binding Proteins
  • HIV Envelope Protein gp120
  • Interleukin-7
  • Milk Proteins
  • RNA, Messenger
  • Receptors, Interleukin-7
  • STAT5 Transcription Factor
  • Trans-Activators
  • fas Receptor
  • interleukin-7 receptor, alpha chain