Transcriptional activation of heme oxygenase-1 and its functional significance in acetaminophen-induced hepatitis and hepatocellular injury in the rat.
OBJECTIVE
Glutathione depletion contributes to acetaminophen hepatotoxicity and is known to induce the oxidative stress reactant heme oxygenase-1. The metabolites of the heme oxygenase pathway, biliverdin, carbon monoxide, and iron may modulate acetaminophen toxicity. The aim of this study was to assess cell-type specific expression of heme oxygenase-1 and its impact on liver injury and microcirculatory disturbances in a model of acetaminophen-induced hepatitis.


METHODS
Gene expression of heme oxygenase-1 was studied by Northern- and Western analysis as well as immunohistochemistry. The time course of heme oxygenase-1 and -2, cytokine-induced neutrophil chemoattractant-1, and intercellular adhesion molecule-1 was studied by Northern analysis. DNA-binding activity of nuclear factor-kappaB was determined by electrophoretic mobility shift assay. Sinusoidal perfusion and leukocyte-endothelial interactions were assessed by intravital microscopy.


RESULTS
Acetaminophen caused a moderate sinusoidal perfusion failure (-15%) and infiltration of neutrophils along with activation of nuclear factor-kappaB and intercellular adhesion molecule-1 and cytokine-induced neutrophil chemoattractant-1 mRNAs. Induction of heme oxygenase-1 mRNA and protein (approximately 30-fold) in hepatocytes and non-parenchymal cells paralleled the inflammatory response. Blockade of heme oxygenase activity with tin-protoporphyrin-IX abrogated acetaminophen-induced hepatic neutrophil accumulation and nuclear factor-kappaB activation, but failed to affect sinusoidal perfusion and liver injury.


CONCLUSIONS
The inflammatory response associated with acetaminophen hepatotoxicity is modulated by the parallel induction of the heme oxygenase-1 gene. However, heme oxygenase-1 has no permissive effect on sinusoidal perfusion and does not affect liver injury in this model. These data argue against a central role of nuclear factor-kappaB activation and neutrophil infiltration as perpetuating factors of liver injury in acetaminophen toxicity.
Bauer
I
I
Department of Anesthesiology and Critical Care Medicine, University of the Saarland, Homburg, Germany.
Vollmar
B
B
Jaeschke
H
H
Rensing
H
H
Kraemer
T
T
Larsen
R
R
Bauer
M
M
D000082:Acetaminophen / Q000097:blood; D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D056486:Chemical and Drug Induced Liver Injury / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006419:Heme Oxygenase (Decyclizing) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051547:Heme Oxygenase-1; D006439:Hemodynamics / Q000187:drug effects; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007962:Leukocytes / Q000473:pathology; D008099:Liver / Q000201:enzymology / Q000473:pathology; D008102:Liver Circulation / Q000187:drug effects; D008665:Metalloporphyrins / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism; D011524:Protoporphyrins / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014018:Tissue Distribution; D015533:Transcriptional Activation / Q000502:physiology*
D004791:Enzyme Inhibitors; D008665:Metalloporphyrins; D016328:NF-kappa B; D011524:Protoporphyrins; D000082:Acetaminophen; C032628:tin protoporphyrin IX; D007770:L-Lactate Dehydrogenase; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D000410:Alanine Transaminase