Heme oxygenase-1 protects human hepatocytes in vitro against warm and cold hypoxia.
OBJECTIVE
Hepatic injury induced by ischemia/reperfusion following surgery, transplantation, or circulatory shock combined with resuscitation is a major clinical problem.


METHODS
In this study, hypoxic and inflammatory conditions were mimicked by exposing human hepatocytes to N(2) (at 4 and 37 degrees C) or to cytokines/endotoxin to investigate the potential protective effects of heme oxygenase-1 (HO-1). Incubation of human hepatocytes with single cytokines (IFN-gamma, IL-1beta, TNF-alpha) or LPS, as well as a combination of all four stimuli (CM, cytomix) caused a time-dependent HO-1 mRNA expression over 12h and a decline by 24 h. In parallel, we observed a time-dependent membrane leakage for LDH and AST and a maximum HO-1 protein expression between 3-24 h.


RESULTS
Warm and cold hypoxia showed similar results in HO-1 mRNA and protein expression and the release of LDH and AST. CoPP, a potent HO-1 inducer, and bilirubin, a co-product of the HO-pathway, protected human hepatocytes from warm and cold hypoxia. HO-1 enzyme activity was highest during warm hypoxia, followed by cold hypoxia and CM which was confirmed by intracellular Fe(2+) formation.


CONCLUSIONS
Taken together, we demonstrated, that HO-1 induction protected human hepatocytes against warm and cold hypoxia. Our results also suggest that HO-1 induction may have therapeutic potential against inflammatory insults.
Tüzüner
Eda
E
Department of General-, Visceral-, and Transplantation Surgery, Universitätsmedizin Berlin, Campus Virchow, Germany.
Liu
Liegang
L
Shimada
Masashi
M
Yilmaz
Eser
E
Glanemann
Matthias
M
Settmacher
Utz
U
Langrehr
Jan M
JM
Jonas
Sven
S
Neuhaus
Peter
P
Nussler
Andreas K
AK
D001219:Aspartate Aminotransferases / Q000378:metabolism; D002478:Cells, Cultured; D003080:Cold Temperature; D016207:Cytokines / Q000494:pharmacology; D004731:Endotoxins / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics* / Q000378:metabolism*; D051547:Heme Oxygenase-1; D022781:Hepatocytes / Q000166:cytology / Q000201:enzymology*; D006358:Hot Temperature; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D066298:In Vitro Techniques; D007511:Ischemia / Q000378:metabolism; D008565:Membrane Proteins; D009569:Nitric Oxide / Q000378:metabolism; D011524:Protoporphyrins / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D017382:Reactive Oxygen Species / Q000378:metabolism; D018805:Sepsis / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
D016207:Cytokines; D004731:Endotoxins; D008565:Membrane Proteins; D011524:Protoporphyrins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; C007095:cobaltiprotoporphyrin; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D001219:Aspartate Aminotransferases