Influence of Kupffer cells and platelets on ischemia-reperfusion injury in mild steatotic liver

AIM: To investigate the effect of mild steatotic liver on ischemia-reperfusion injury by focusing on Kupffer cells (KCs) and platelets. METHODS: Wistar rats were divided into a normal liver group (N group) and a mild steatotic liver group (S group) induced by feeding a choline-deficient diet for 2 wk. Both groups were subjected to 20 min of warm ischemia followed by 120 min of reperfusion. The number of labeled KCs and platelets in sinusoids and the blood perfusion in sinusoids were observed by intravital microscopy (IVM), which was performed at 30, 60 and 120 min after reperfusion. To evaluate serum alanine aminotransferase as a marker of liver deterioration, blood samples were taken at the same time as IVM.RESULTS: In the S group, the number of platelets adhering to KCs decreased significantly compared with the N group (120 after reperfusion; 2.9±1.1 cells/acinus vs 4.8±1.2 cells/acinus, P<0.01). The number of KCs in sinusoids was significantly less in the S group than in the N group throughout the observation periods (before ischemia, 19.6±3.3 cells/acinus vs 28.2±4.1 cells/acinus, P<0.01 and 120 min after reperfusion, 29.0±4.3 cells/acinus vs 40.2±3.3 cells/acinus, P<0.01). The blood perfusion of sinusoids 120 min after reperfusion was maintained in the S group more than in the N group. Furthermore, elevation of serum alanine aminotransferase was lower in the S group than in the N group 120 min after reperfusion (99.7±19.8 IU/L vs 166.3±61.1 IU/L, P=0.041), and histological impairment of hepatocyte structure was prevented in the S group. CONCLUSION: Ischemia-reperfusion injury in mild steatotic liver was attenuated compared with normal liver due to the decreased number of KCs and the reduction of the KC-platelet interaction.

Evaluation of safety for hepatectomy in a novel mouse model with nonalcoholic-steatohepatitis

AIM To investigate whether the liver resection volume in a newly developed nonalcoholic steatohepatitis(NASH) model influences surgical outcome.METHODS For establishment of a NASH model, mice were fed a high-fat diet for 4 wk, administered CCl_4 for the last 2 wk, and administered T0901317 for the last 5 d. We divided these mice into two groups: A 30% partial hepatectomy(PH) of NASH liver group and a 70% PH of NASH liver group. In addition, a 70% PH of normal liver group served as the control. Each group was evaluated for survival rate, regeneration, apoptosis, necrosis and DNA expression after PH.RESULTS In the 70% PH of NASH group, the survival rate was significantly decreased compared with that in the control and 30% PH of NASH groups(P < 0.01). 10 of 32 mice in the NASH 70% PH group died within 48 h after PH. Serum aspartate aminotransferase(AST) levels and total bilirubin(T-Bil) in the NASH 70% PH group were significantly higher than the levels in the other two groups(AST: P < 0.05, T-Bil: P < 0.01). In both PH of NASH groups, signaling proteins involved in regeneration were expressed at lower levels than those in the control group(P < 0.01). The 70% PH of NASH group also exhibited a lower number of Ki-67-positive cells and higher rates of apoptosis and necrosis than the NASH 30% PH group(P < 0.01). In addition, DNA microarray assays showed differences in gene expression associated with cell cycle arrest and apoptosis.CONCLUSION The function of the residual liver is impaired in fatty liver compared to normal liver. A larger residual volume is required to maintain liver functions in mice with NASH.

New drug delivery system for liver sinusoidal endothelial cells for ischemia-reperfusion injury

AIM: To investigate the cytoprotective effects in hepatic ischemia-reperfusion injury, we developed a new formulation of hyaluronic acid(HA) and sphingosine 1-phophate.METHODS: We divided Sprague-Dawley rats into 4 groups: control, HA, sphingosine 1-phosphate(S1P), and HA-S1 P. After the administration of each agent, we subjected the rat livers to total ischemia followed by reperfusion. After reperfusion, we performed the following investigations: alanine aminotransferase(ALT), histological findings, Td T-mediated d UTP-biotin nick end labeling(TUNEL) staining, and transmission electron microscopy(TEM). We also investigated the expressionof proteins associated with apoptosis, hepatoprotection, and S1 P accumulation. RESULTS: S1 P accumulated in the HA-S1 P group livers more than S1 P group livers. Serum ALT levels, TUNEL-positive hepatocytes, and expression of cleaved caspase-3 expression, were significantly decreased in the HA-S1 P group. TEM revealed that the liver sinusoidal endothelial cell(LSEC) lining was preserved in the HA-S1 P group. Moreover, the HA-S1 P group showed a greater increase in the HO-1 protein levels compared to the S1 P group.CONCLUSION: Our results suggest that HA-S1 P exhibits cytoprotective effects in the liver through the inhibition of LSEC apoptosis. HA-S1 P is an effective agent for hepatic ischemia/reperfusion injury.