Ischemic preconditioning protects against liver ischemia/reperfusion injury via heme oxygenase-1-mediated autophagy

Crit Care Med. 2014 Dec;42(12):e762-71. doi: 10.1097/CCM.0000000000000659.

Abstract

Objectives: Ischemic preconditioning exerts a protective effect in hepatic ischemia/reperfusion injury. The exact mechanism of ischemic preconditioning action remains largely unknown. Recent studies suggest that autophagy plays an important role in protecting against ischemia/reperfusion injury. However, the role of autophagy in ischemic preconditioning-afforded protection and its regulatory mechanisms in liver ischemia/reperfusion injury remain poorly understood. This study was designed to determine whether ischemic preconditioning could protect against liver ischemia/reperfusion injury via heme oxygenase-1-mediated autophagy.

Design: Laboratory investigation.

Setting: University animal research laboratory.

Subjects: Male inbred Lewis rats and C57BL/6 mice.

Interventions: Ischemic preconditioning was produced by 10 minutes of ischemia followed by 10 minutes of reperfusion prior to 60 minutes of ischemia. In a rat model of hepatic ischemia/reperfusion injury, rats were pretreated with wortmannin or rapamycin to evaluate the contribution of autophagy to the protective effects of ischemic preconditioning. Heme oxygenase-1 was inhibited with tin protoporphyrin IX. In a mouse model of hepatic ischemia/reperfusion injury, autophagy or heme oxygenase-1 was inhibited with vacuolar protein sorting 34 small interfering RNA or heme oxygenase-1 small interfering RNA, respectively.

Measurements and main results: Ischemic preconditioning ameliorated liver ischemia/reperfusion injury, as indicated by lower serum aminotransferase levels, lower hepatic inflammatory cytokines, and less severe ischemia/reperfusion-associated histopathologic changes. Ischemic preconditioning treatment induced autophagy activation, as indicated by an increase of LC3-II, degradation of p62, and accumulation of autophagic vacuoles in response to ischemia/reperfusion injury. When ischemic preconditioning-induced autophagy was inhibited with wortmannin in rats or vacuolar protein sorting 34-specific small interfering RNA in mice, liver ischemia/reperfusion injury was worsened, whereas rapamycin treatment increased autophagy and mimicked the protective effects of ischemic preconditioning. Furthermore, ischemic preconditioning increased heme oxygenase-1 expression. The inhibition of heme oxygenase-1 with tin protoporphyrin IX in rats or heme oxygenase-1-specific small interfering RNA in mice decreased ischemic preconditioning-induced autophagy and diminished the protective effects of ischemic preconditioning against ischemia/reperfusion injury.

Conclusions: Ischemic preconditioning protects against liver ischemia/reperfusion injury, at least in part, via heme oxygenase-1-mediated autophagy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy / physiology*
  • Class III Phosphatidylinositol 3-Kinases / pharmacology
  • Cytokines / metabolism
  • Disease Models, Animal
  • Heme Oxygenase-1 / biosynthesis*
  • Ischemic Preconditioning*
  • Liver Diseases / prevention & control*
  • Male
  • Metalloporphyrins / pharmacology
  • Mice
  • Mice, Inbred C57BL
  • Protoporphyrins / pharmacology
  • RNA, Small Interfering
  • Rats
  • Rats, Inbred Lew
  • Reperfusion Injury / physiopathology
  • Reperfusion Injury / prevention & control*
  • Transaminases / metabolism

Substances

  • Cytokines
  • Metalloporphyrins
  • Protoporphyrins
  • RNA, Small Interfering
  • tin protoporphyrin IX
  • Heme Oxygenase-1
  • Transaminases
  • Class III Phosphatidylinositol 3-Kinases