Interferon regulatory factor-2 is protective against hepatic ischemia-reperfusion injury

Am J Physiol Gastrointest Liver Physiol. 2012 Sep 1;303(5):G666-73. doi: 10.1152/ajpgi.00050.2012. Epub 2012 Jun 28.

Abstract

Interferon regulatory factor (IRF)-1 is a nuclear transcription factor that induces inflammatory cytokine mediators and contributes to hepatic ischemia-reperfusion (I/R) injury. No strategies to mitigate IRF1-mediated liver damage exist. IRF2 is a structurally similar endogenous protein that competes with IRF1 for DNA binding sites in IRF-responsive target genes and acts as a competitive inhibitor. However, the role of IRF2 in hepatic injury during hypoxic or inflammatory conditions is unknown. We hypothesize that IRF2 overexpression may mitigate IRF1-mediated I/R damage. Endogenous IRF2 is basally expressed in normal livers and is mildly increased by ischemia alone. Overexpression of IRF2 protects against hepatic warm I/R injury. Furthermore, we demonstrate that IRF2 overexpression limits production of IRF1-dependent proinflammatory genes, such as IL-12, IFNβ, and inducible nitric oxide synthase, even in the presence of IRF1 induction. Additionally, isograft liver transplantation with IRF2 heterozygote knockout (IRF2(+/-)) donor grafts that have reduced endogenous IRF2 levels results in worse injury following cold I/R during murine orthotopic liver transplantation. These findings indicate that endogenous intrahepatic IRF2 protein is protective, because the IRF2-deficient liver donor grafts exhibited increased liver damage compared with the wild-type donor grafts. In summary, IRF2 overexpression protects against I/R injury by decreasing IRF1-dependent injury and may represent a novel therapeutic strategy.

Publication types

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

MeSH terms

  • Adenoviridae
  • Animals
  • Blotting, Western
  • Cell Culture Techniques
  • Gene Expression
  • Genetic Vectors
  • Hepatocytes / metabolism*
  • Humans
  • Interferon Regulatory Factor-1 / genetics
  • Interferon Regulatory Factor-1 / metabolism*
  • Interferon Regulatory Factor-2 / genetics
  • Interferon Regulatory Factor-2 / metabolism
  • Liver / metabolism*
  • Liver Transplantation
  • Male
  • Mice
  • Real-Time Polymerase Chain Reaction
  • Reperfusion Injury / metabolism*
  • Reperfusion Injury / prevention & control

Substances

  • IRF1 protein, human
  • IRF2 protein, human
  • Interferon Regulatory Factor-1
  • Interferon Regulatory Factor-2