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


METHODS
Laboratory investigation.


METHODS
University animal research laboratory.


METHODS
Male inbred Lewis rats and C57BL/6 mice.


METHODS
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.


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.
1Experimental Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. 2Experimental Transplantation Surgery, Department of General, Visceral and Vascular Surgery, University Hospital of Jena, Friedrich-Schiller-University Jena, Jena, Germany. 3Department of Pathophysiology, Anhui Medical University, Hefei, China. 4Institute for Pathology, University Hospital of Jena, Friedrich-Schiller-University Jena, Jena, Germany.
Anding
A
Liu
Haoshu
H
Fang
Weiwei
W
Wei
Olaf
O
Dirsch
Uta
U
Dahmen
D000818:Animals; D001343:Autophagy / Q000502:physiology*; D058546:Class III Phosphatidylinositol 3-Kinases / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D051547:Heme Oxygenase-1 / Q000096:biosynthesis*; D019194:Ischemic Preconditioning; D008107:Liver Diseases / Q000517:prevention & control*; D008297:Male; D008665:Metalloporphyrins / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D011524:Protoporphyrins / Q000494:pharmacology; D034741:RNA, Small Interfering; D051381:Rats; D011917:Rats, Inbred Lew; D015427:Reperfusion Injury / Q000503:physiopathology / Q000517:prevention & control*; D000637:Transaminases / Q000378:metabolism
D016207:Cytokines; D008665:Metalloporphyrins; D011524:Protoporphyrins; D034741:RNA, Small Interfering; C032628:tin protoporphyrin IX; D051547:Heme Oxygenase-1; D000637:Transaminases; D058546:Class III Phosphatidylinositol 3-Kinases