STAT3 regulates proliferation and survival of CD8+ T cells: enhances effector responses to HSV-1 infection, and inhibits IL-10+ regulatory CD8+ T cells in autoimmune uveitis

Mediators Inflamm. 2013;2013:359674. doi: 10.1155/2013/359674. Epub 2013 Sep 24.

Abstract

STAT3 regulates CD4+ T cell survival and differentiation. However, its effects on CD8+ T cells are not well understood. Here, we show that in comparison to WT CD8+ T cells, STAT3-deficient CD8+ T cells exhibit a preactivated memory-like phenotype, produce more IL-2, proliferate faster, and are more sensitive to activation-induced cell death (AICD). The enhanced proliferation and sensitivity to AICD correlated with downregulation of class-O forkhead transcription factors (FoxO1, FoxO3A), p21(waf1), p27(KIP1), Bcl-2, OX-40, and upregulation of FasL, Bax, and Bad. We examined whether STAT3-deficient CD8+ T cells can mount effective response during herpes simplex virus (HSV-1) infection and experimental autoimmune uveitis (EAU). Compared to WT mice, HSV-1-infected STAT3-deficient mice (STAT3KO) produced less IFN-γ and virus-specific KLRG-1+ CD8+ T cells. STAT3KO mice are also resistant to EAU and produced less IL-17-producing Tc17 cells. Resistance of STAT3KO to EAU correlated with marked expansion of IL-10-producing regulatory CD8+ T cells (CD8-Treg) implicated in recovery from autoimmune encephalomyelitis. Thus, increases of IL-6-induced STAT3 activation observed during inflammation may inhibit expansion of CD8-Tregs, thereby impeding recovery from uveitis. These results suggest that STAT3 is a potential therapeutic target for upregulating CD8+ T cell-mediated responses to viruses and suggest the successful therapeutic targeting of STAT3 as treatment for uveitis, derived, in part, from promoting CD8-Treg expansion.

MeSH terms

  • Animals
  • Apoptosis
  • Autoimmune Diseases / immunology
  • CD8-Positive T-Lymphocytes / cytology*
  • Cell Proliferation
  • Cell Separation
  • Flow Cytometry
  • Gene Expression Regulation
  • Herpes Simplex / metabolism*
  • Herpes Simplex / virology
  • Herpesvirus 1, Human
  • Inflammation
  • Interleukin-10 / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Phenotype
  • STAT3 Transcription Factor / genetics*
  • STAT3 Transcription Factor / metabolism
  • Up-Regulation
  • Uveitis / immunology*
  • Uveitis / virology

Substances

  • STAT3 Transcription Factor
  • Stat3 protein, mouse
  • Interleukin-10