Type 1 interferon-induced IL-7 maintains CD8+ T-cell responses and homeostasis by suppressing PD-1 expression in viral hepatitis

Cell Mol Immunol. 2015 Mar;12(2):213-21. doi: 10.1038/cmi.2014.49. Epub 2014 Jul 14.

Abstract

Type 1 interferon (IFN-I) promotes antigen-presenting cell maturation and was recently shown to induce hepatic IL-7 production during infection. Herein, we further explored the underlying mechanisms used by IFN-I to orchestrate antiviral immune responses in the liver. Acute viral hepatitis was induced by i.v. injection of adenovirus (Ad) in IFN-α receptor knockout (IFNAR(-/-)) and control mice. To disrupt signaling, monoclonal antibodies (mAbs) against IL-7 receptor alpha (IL-7Rα) or PD-L1 were i.p. injected. We found that CD8(+) T cells in IFNAR(-/-) mice were less effective than those in control mice. The reduced T-cell function was accompanied by increased levels of PD-1 expression, apoptosis and decreased IFN-γ production. The lack of IFN-I signaling also impaired the expression of accessory molecules in both intrahepatic dendritic cell (DCs) and hepatocytes. PD-L1 was comparably and highly expressed on hepatocytes in both IFNAR(-/-) and control mice. Injection of PD-L1-specific mAb in IFNAR(-/-) mice reversed the compromised immune responses in the liver. Further investigation showed that hepatic IL-7 elevation was less pronounced in IFNAR(-/-) mice compared to the controls. A treatment with recombinant IL-7 suppressed PD-1 expression on CD8(+) T cells in vitro. Accordingly, blocking IL-7R signaling in vivo resulted in increased PD-1 expression on CD8(+) T cells in Ad-infected mice. Collectively, the results suggest that IFN-I-induced hepatic IL-7 production maintains antiviral CD8(+) T-cell responses and homeostasis by suppressing PD-1 expression in acute viral hepatitis.

Publication types

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

MeSH terms

  • Animals
  • Antigen-Presenting Cells / drug effects
  • Antigen-Presenting Cells / immunology*
  • Antigen-Presenting Cells / metabolism
  • Antiviral Agents / pharmacology
  • Blotting, Western
  • CD8-Positive T-Lymphocytes / drug effects
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / metabolism
  • Cells, Cultured
  • Dendritic Cells / drug effects
  • Dendritic Cells / immunology
  • Dendritic Cells / metabolism
  • Female
  • Flow Cytometry
  • Hepatitis / drug therapy
  • Hepatitis / etiology*
  • Hepatitis / pathology
  • Homeostasis
  • Interferon Type I / pharmacology*
  • Interferon-gamma / metabolism
  • Interleukin-7 / immunology*
  • Interleukin-7 / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Programmed Cell Death 1 Receptor / genetics
  • Programmed Cell Death 1 Receptor / metabolism*
  • RNA, Messenger / genetics
  • Real-Time Polymerase Chain Reaction
  • Receptor, Interferon alpha-beta / physiology*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction
  • T-Lymphocytes, Cytotoxic / drug effects
  • T-Lymphocytes, Cytotoxic / immunology
  • T-Lymphocytes, Cytotoxic / metabolism

Substances

  • Antiviral Agents
  • Ifnar1 protein, mouse
  • Interferon Type I
  • Interleukin-7
  • Pdcd1 protein, mouse
  • Programmed Cell Death 1 Receptor
  • RNA, Messenger
  • Receptor, Interferon alpha-beta
  • Interferon-gamma