The role of heme oxygenase-1 in drug metabolizing dysfunction in the alcoholic fatty liver exposed to ischemic injury.

This study was designed to investigate the role of heme oxygenase-1 (HO-1) in hepatic drug metabolizing dysfunction after ischemia/reperfusion (IR) in alcoholic fatty liver (AFL). Rats were fed a Lieber-DeCarli diet for five weeks to allow for development of AFL and were then subjected to 90min of hepatic ischemia and 5h of reperfusion. Rats were pretreated with hemin (HO-1 inducer) or ZnPP (HO-1 inhibitor) for 16h and 3h before hepatic ischemia. After hepatic IR, ethanol diet (ED)-fed rats had higher serum aminotransferase activities and more severe hepatic necrosis compared to the control diet (CD)-fed rats. These changes were attenuated by hemin and exacerbated by ZnPP. The activity and gene expression of HO-1 and its transcription factor (Nrf2) level increased significantly after 5h of reperfusion in CD-fed rats but not in ED-fed rats. After reperfusion, cytochrome P450 (CYP) 1A1, 1A2, and 2B1 activities were reduced to levels lower than those observed in sham group, whereas CYP2E1 activity increased. The decrease in CYP2B1 activity and the increase in CYP2E1 activity were augmented after hepatic IR in ED-fed animals. These changes were significantly attenuated by hemin but aggravated by ZnPP. Finally, CHOP expression and PERK phosphorylation, microsomal lipid peroxidation, and levels of proinflammatory mediators increased in ED-fed rats compared to CD-fed rats after reperfusion. These increases were attenuated by hemin. Our results suggest that AFL exacerbates hepatic drug metabolizing dysfunction during hepatic IR via endoplasmic reticulum stress and lipid peroxidation and this is associated with impaired HO-1 induction.

Park SW ，Kang JW ，Lee SM 《-》

Role of Kupffer cells in ischemic injury in alcoholic fatty liver.

This study was designed to evaluate the role of Kupffer cells (KCs) in hepatic drug metabolizing dysfunction after hepatic ischemia-reperfusion (IR) in alcoholic fatty liver. Rats were fed the Lieber-DeCarli diet for 5 wk to develop alcoholic fatty liver, then were subjected to 90 min of hepatic ischemia and 5 h of reperfusion. For ablation of KCs, rats were pretreated with gadolinium chloride (GdCl3) 48 and 24 h before the IR procedure. After the IR procedure, ethanol diet (ED)-fed rats had higher serum aminotransferase activity compared with the control diet-fed rats. These changes were attenuated by GdCl3. The ED-fed rats exhibited increased hepatic microsomal total cytochrome P450 (CYP) content and nicotinamide adenine dinucleotide phosphate-CYP reductase and CYP1A1, 1A2, 2B1, and 2E1 isozyme activity. After hepatic IR, these increases were reduced to lower levels than observed in the sham group, except CYP2E1 activity. Increases in CYP2E1 activity and its expression were augmented after hepatic IR in ED-fed animals, but were attenuated by GdCl3. Finally, toll-like receptor 4 and myeloid differentiation primary response gene 88 protein expression, nuclear translocation of nuclear factor-κB and activator protein 1, and levels of proinflammatory mediators were further increased in ED-fed animals compared with control diet-fed animals after IR. These increases were attenuated by GdCl3. We suggest that KCs contribute to hepatic drug metabolizing dysfunction during hepatic IR in alcoholic fatty liver via the toll-like receptors 4-mediated inflammatory response.

Park SW ，Kang JW ，Lee SM 《-》

Protective effect of heme oxygenase-1 induction against hepatic injury in alcoholic steatotic liver exposed to cold ischemia/reperfusion.

The purpose of this study was to investigate the cytoprotective role of heme oxygenase-1 (HO-1) induction in hepatic injury in alcoholic steatotic liver exposed to cold ischemia/reperfusion (I/R). Animals were fed an ethanol liquid diet or isocaloric control diet for 5 weeks. Isolated perfused rat livers were preserved in Histidine-Tryptophan-Ketoglutarate at 4 °C. After 24 h of storage, livers were subjected to 120 min of reperfusion with Krebs-Henseleit bicarbonate buffer at 37 °C. Animals were pretreated with cobalt protoporphyrin (CoPP, 5 mg/kg, i.p.) or zinc protoporphyrin (ZnPP, 25 mg/kg, i.p.), HO-1 inducer and antagonist, respectively. In the model of ischemia/isolated perfusion, endogenous HO-1 was downregulated in the livers fed with ethanol diet (ED I/R). In ED I/R group, portal pressure and lactate dehydrogenase release were significantly increased, while bile output and hyaluronic acid clearance decreased compared to rats fed on control diet (CD I/R). Furthermore, hepatic glutathione content decreased and lipid peroxidation increased in the ED I/R group compared to the CD I/R group. These alterations were attenuated by upregulation of HO-1 with CoPP pretreatment. Our results suggest that chronic ethanol consumption aggravates hepatic injury during cold I/R and it is likely due to downregulation of endogenous HO-1. Prior induction of HO-1 expression may provide a new strategy to protect livers against hepatic I/R injury or to increase the donor transplant pool through modulation of marginal alcoholic steatotic livers.

Kim SJ ，Park JG ，Lee SM 《-》

[Protective effects of luteolin preconditioning on rat liver under ischemia/reperfusion].

The aim of the study is to explore the effects of luteolin preconditioning on hepatic ischemia/reperfusion injury in rats and its mechanism, and investigate the effects of the change of heme oxygenase-1 (HO-1) activity on hepatic ischemia/reperfusion injury. Sprague-Dawley rats were divided into 5 groups randomly: control, model, luteolin, luteolin + zinc protoporphyrin (ZnPP, an inhibitor of HO-1) and hemin groups (n = 8 for each group). The rats in control, model and hemin groups received a standard chow daily. The rats in luteolin and luteolin + ZnPP groups received a chow supplemented with luteolin (200 mg/kg) daily. After 4 weeks, ZnPP (25 μmol/kg) and hemin (20 μmol/kg) were injected hypodermically 6 h before ischemia/reperfusion in luteolin + ZnPP and hemin groups, respectively. Portal vein and hepatic artery supplying the middle and left hepatic lobe were clamped with an atraumatic vascular clip for induction of partial hepatic ischemia in all rats except control group. After the 60 min of hepatic ischemia, a 60-minute reperfusion period was initiated by removal of the arterial clip. The levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were detected in serum, and the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in serum and liver were measured with assay kit. The expression of HO-1 protein and activity of HO-1 were examined in liver. The results showed that the luteolin and hemin pretreatment led to significant decreased levels of AST and ALT in serum, increased activity of SOD and decreased content of MDA in serum and liver compared with model group (P < 0.01). In addition, the expression of HO-1 protein and activity of HO-1 were elevated in luteolin and hemin groups (P < 0.01). ZnPP markedly increased the levels of AST and ALT in serum, and decreased the activities of SOD and HO-1, elevated MDA content in liver when compared with those in luteolin group (P < 0.01). Cytoplasmic vacuolation and swelling of hepatocytes were revealed in the model group after ischemia/reperfusion. Treatments with luteolin and hemin markedly relieved the liver structural changes. These results suggest that HO-1 protects rat liver from ischemia/reperfusion injury, and luteolin reduces the content of MDA and increases the activity of SOD and the expression of HO-1, which indicate that luteolin can elevate the antioxidation in rat liver, and thus protects rat liver from ischemia/reperfusion injury.

Wang GG ，Lu XH ，Ding M ，Tang WT ，Li W ，Zhao X ，Zhang C ... -  《-》

Altered activity of cytochrome P450 in alcoholic fatty liver exposed to ischemia/reperfusion.

Cho KH ，Lee SM 《ARCHIVES OF PHARMACAL RESEARCH》