The mechanism of hepatic graft protection against reperfusion injury by prostaglandin E1

PRELIMINARY RESULTS OF TOPICAL HEPATIC HYPOTHERMIA IN A MODEL OF LIVER ISCHEMIA/REPERFUSION INJURY IN RATS

BACKGROUND

Ischemia/reperfusion causes organ damage but it is mandatory in hepatic transplantation, trauma and other complex liver surgeries, when Pringle maneuver is applied to minimize bleeding during these procedures. It is well known that liver ischemia/reperfusion leads to microcirculatory disturbance and cellular injury. In this setting hypothermia is known to reduce oxygen demand, lowering intracellular metabolism.

OBJECTIVE:

To evaluate the effects of hypothermia in liver ischemia/reperfusion injury, using a new model of topic isolated liver hypothermia.

METHODS

We used male Wistar rats weighting about 250 grams, kept in ad libitum feeding regime and randomly divided into two groups of nine animals: 1) Normothermic group, rats were submitted to normothermic ischemia of the median and left hepatic lobes, with subsequent resection of right and caudate lobes during liver reperfusion; and 2) Hypothermic group, rats were submitted to liver ischemia under hypothermia at 10°C. Liver ischemia was performed for 45 minutes. The animals were euthanized 48 hours after liver reperfusion for blood and liver tissue sampling.

RESULTS

The transaminases analyses showed a significant decrease of AST and ALT in Hypothermic group (P<0.01) compared to Normothermic group (1403±1234 x 454±213 and 730±680 x 271±211 U/L, respectively). Histology showed severe necrosis in 50% and mild necrosis in 50% of cases in Normothermic group, but severe necrosis in 10% and mild or absent necrosis 90% of the cases in hypothermic group.

CONCLUSION:

A simplified model of liver ischemia/reperfusion that simulates orthotopic liver autotransplantion was demonstrated. Topical hypothermia of isolated hepatic lobules showed liver protection, being a viable and practical method for any kind of in vivo liver preservation study.

Soluble Thrombomodulin Ameliorates Ischemia-Reperfusion Injury of Liver Grafts by Modulating the Proinflammatory Role of High-Mobility Group Box 1

Transplantation using grafts obtained after cardiac death (CD) is considered a promising solution for graft shortages. However, no standard criteria for organ preservation have been established for CD donors. High-mobility group box 1 (HMGB1) is a DNA-binding protein that is released from dying hepatocytes as an early mediator of inflammation and organ tissue damage. HMGB1 stimulates immunocytes to produce inflammatory cytokines, thereby amplifying the inflammatory response. Thrombomodulin is an integral membrane protein that functions as an endothelial anticoagulant cofactor, and it binds HMGB1 through the extracellular domain. We investigated the effects of ART-123, recombinant human soluble thrombomodulin, on warm ischemia-reperfusion injury in liver grafts. Male Wistar rats were divided into four ex vivo groups: heart-beating (HB) group, in which livers were isolated from HB donors; CD group, in which livers were isolated from CD donors exposed to apnea-induced conditions and warm ischemic conditions for 30 min after cardiac arrest; and two CD groups pretreated with ART-123 (1 or 5 mg/kg). Each isolated liver was reperfused for 1 h after cold preservation for 6 h. The perfusate levels of HMGB1, LDH, TNF-α, and IL-6 were significantly lower in the CD group pretreated with ART-123 (5 mg/kg) than in the CD group. Bile production was significantly higher in the CD group pretreated with ART-123 (5 mg/kg) than in the CD group. The sinusoidal spaces were significantly narrower in the CD group than in the other groups. We propose that ART-123 maintains sinusoidal microcirculation by reducing endothelial cell damage during warm ischemia-reperfusion injury.

Effect of prostaglandin E-1 on Wisconsin University and histidine-tryptophan-ketoglutarate preservation solutions on preservation injury of the perfused liver

BACKGROUND

The aim of this study was to investigate the effects of prostaglandin E-1 (PGE-1) on preservation injury in livers perfused with the University of Wisconsin (UW) or histidine-tryptophan-ketoglutarate (HTK) solutions.

MATERIALS AND METHODS

Five groups each including six rats included. Ringer's lactate RL (group 1), HTK (group 2), HTK + PGE-1 (group 3), UW (group 4), or UW PGE-1 (group 5). Liver tissue and preservation fluid samples were obtained from the perfused lives for pathological and biochemical examinations respectively at 0, 6 and 12 hours.

RESULTS

Upon biochemical examination, aspartate aminotrasnferase and alanine aminotransferase values were highest among the group with RL solution and lowest with PGE-1. Liver structure was found to be damaged immediately after RL solution, whereas it was preserved in the other four groups. Fewer cellular changes were reported at the end of 12 hours in the groups administered PGE-1 compared with the other groups.

CONCLUSIONS

PGE-1 when applied before preservation protected liver functions, decreased pathologic injury, and delayed changes that occur under cold ischemic conditions.

Role of oxidative stress in the pathogenesis of chronic hepatic injury induced by ethanol and carbon tetrachloride in rats

AIM: To investigate the role of oxidative stress reaction in the pathogenesis of chronic hepatic injury induced by alcohol and carbon tetrachloride (CCl4) in rats.

METHODS: Fifty male Wistar rats were divided equally into five groups: A, B, C, D and E. The experiment was continued for 8 weeks in each group. Groups A and B were perfused intragastrically with normal saline and alcohol, respectively. Group C was treated as group B and additionally injected intraperitoneally with prostaglandin E1 (PGE1). Group D was perfused intragastrically with alcohol for 4 weeks and injected intraperitoneally with CCl4 for another 4 weeks. Group E was treated as group D and additionally injected intraperitoneally with PGE1. At weeks 4 and 8, serum ALT, AST, ALP, TBA, TG, CHO, GSH-Px, and MDA were determined. At week 8, all rats were executed to take hepatic tissue specimens for observation of histopathological alterations.

RESULTS: No significant differences were found in the original body weight (BW) among the five groups before the treatment. Compared with group A, at week 8, the BW and increased BW significantly decreased (249.00 g ± 18.83 g and 258.50 g ± 20.28 g vs 319.00 g ± 29.61 g; 65.00 g ± 15.28 g and 76.50 g ± 15.82 g vs 134.00 g ± 21.58 g, respectively; all P < 0.01), and the liver mass (expressed as the percentage of total BW) significantly increased (3.267% ± 0.3165% and 4.735% ± 0.7567% vs 2.736% ± 0.1988%, respectively; both P < 0.01) in groups B and D. After pre-treatment with PGE1 (groups C and E), the decrease in body weight and the increase in liver mass were improved (all P < 0.01). Alcohol and CCl₄ (groups B and D) elevated serum ALT, AST, ALP, TBA, TG, CHO and MDA levels (all P < 0.01 or 0.05), and reduced serum GSH-Px levels (both P < 0.01). After intervention with PGE1, these parameters were improved. In addition, PGE1 pre-treatment could mitigate hepatocyte fatty degeneration, cellular necrosis, inflammatory infiltration and liver fibrosis induced by alcohol and CCl₄.

CONCLUSION: Oxidative stress may play an important role during chronic liver injury induced by alcohol and CCl₄. Inhibition of oxidative stress may be an important measure for alleviating liver injury.

Reperfusion injury in liver transplantation

Reperfusion injury occurring in the transplanted liver is a complex lesion and has been the focus of considerable research over the past decade. This section will review recent major developments in understanding the mechanisms involved and their application to clinical transplantation.

The Use of Prostaglandins in the Immediate Postsurgical Liver Transplant Period

INTRODUCTION

Experimental evidence has suggested that prostaglandins have positive effects on hepatic perfusion after transplantation. However, randomized clinical trials have failed to show their usefulness to decrease the incidence of primary nonfunction. In order to demonstrate its therapeutic role, we performed a clinical study in which PGE1 was administered only after the appearance of posttransplant liver dysfunction.

MATERIALS AND METHODS

Forty patients with macroscopic signs of hypoperfusion or lacking bile production at the end of the operation (n = 24) or with an increase in transaminases and fall in biliary production in the first 24 hours postsurgery (n = 16) were administered alprostadil (PGE1; 0.01 mug/kg/min to the maximum plateau of 0.06 mug/kg/min). We measured the mean values of aspartate aminotransferase (AST), alanine aminotransferase (ALT), activated thromboplastin time-ratio (aPTT-r), international normalized ratio (INR), bilirubin, creatinine and plasma nitrogen, PaO(2)/FiO(2) at the start of the treatment and every 6 hours for 48 hours, and daily diuresis.

RESULTS

There appeared to be a significant decrease in AST, INR, aPTT-r, and creatinine clearance (P < .05), while there was a significant rise in the blood urea nitrogen (P < .001). ALT and bilirubin did not show significant variations. The PaO(2)/FiO(2) ratio showed a significant decrease (P < .001) in pulmonary vasodilatation.

CONCLUSIONS

Prostaglandins used in the manner in our study showed a significant efficiency to improve liver dysfunction after transplantation.

Effect of intraportal infusion to improve small for size graft injury in living donor adult liver transplantation

The most important problem in the living donor adult liver transplantation (LDALT) is a small for size graft. Although a right lobe graft is used in many cases in order to avoid small for size graft, for a donor, the risk has few in left lobe graft. We evaluate the effect of an intraportal infusion treatment to the small for size graft. One hundred and twelve patients who underwent LDALT were studied. The graft weight recipient standard liver volume ratio (GV/SLV) of these patients were 50% or less. We divided the patients into following two groups; infusion group (n = 53) and control group (n = 59). For the infusion group, 16 G double lumen catheter was inserted into portal vein and nafamostat mesilate (protease inhibitor which stabilize coagulofibrinolytic state; 200 mg/day), prostaglandin E(1) (vasodilator and hepatoprotective effect; 500 microg/day) and thromboxane A(2) synthetase inhibitor (vasodilator and anticoagulant effect; 160 mg/day) were administrated continuously for 7 days. Small-for-size graft syndrome was defined as bilirubin >10 mg/dl and ascites >1000 cc on postoperative day (POD) 14. Comparison examination of a background factors and postoperative bilirubin and amount of ascites was carried out. The mean GV/SLV did not have the difference at 39.1% of infusion group, and 38.3% of control group (P = 0.58). By the control group, 15 patients (25.4%) were small-for-size graft syndrome, however, there was only two (3.8%) small-for-size graft syndrome in infusion group (P = 0.04). The bilirubin levels of infusion and control group on 7 and 14 POD were 9.9 and 7.8 vs. 9.5 and 10.5 mg/dl, respectively. The amount of ascites of infusion group on 7 and 14 POD were 870 and 430 cc, respectively. On the contrary, in control group, the amount of ascites on 7 and 14 POD were 1290 and 1070 cc, respectively. Bilirubin levels and the amount of ascites on 7 and 14 POD were lower in the patients with infusion group then those with control group. There were no differences between infusion group and control group in age, sex and Child's classification. The intraportal infusion had an effect in prevention of hyperbilirubinemia and loss in quality of excessive ascites in the patients with small for size graft. This was suggested to be what is depended on the improvement of the microcirculation insufficiency considered one of the causes of small-for-size graft syndrome.

Attenuation of Kupffer cell activation in cold-preserved livers after pretreatment of rats with methylprednisolone or its macromolecular prodrug

PURPOSE

Activation of hepatic Kupffer cells (KCs) during organ preservation and subsequent reperfusion causes release of proinflammatory mediators and is responsible, at least in part, for rejection of transplanted livers. Our hypothesis was that donor pretreatment, before liver harvest, with methylprednisolone (MP) or its dextran prodrug (DMP) would reduce KC activation.

METHODS

Adult donor rats were administered a single 5-mg/kg (MP equivalent) IV dose of MP or DMP or saline 2 h before liver harvest. The livers were then stored in University of Wisconsin solution for 24, 48, or 96 h (n = 4/treatment/time). A recirculating perfusion model was used to study, for 180 min, the release of KC activation markers, tumor necrosis factor (TNF)-alpha and acid phosphatase, and other biochemical indices from the cold-preserved livers.

RESULTS

Cold ischemia-reperfusion resulted in release of substantial levels of TNF-alpha in untreated groups. Pretreatment of rats with MP or DMP caused a significant (p < 0.0001) reduction in TNF-alpha AUC in the perfusate, with no significant differences between MP and DMP. The maximum inhibitory effect of MP (77.5 +/- 10.2%) was observed after 48 h of preservation, whereas DMP showed maximal inhibition of TNF-alpha AUC at both 24 (74.5 +/- 15.8%) and 48 (74.8 +/- 12.6%) h of preservation. Similarly, both MP and DMP resulted in a significant (p < 0.0004) decrease in acid phosphatase levels of cold-preserved livers. However, neither pretreatment had any substantial effect on the levels of other biochemical markers.

CONCLUSIONS

Both MP and DMP pretreatments decreased the release of TNF-alpha and acid phosphatase from livers subjected to cold ischemia preservation. Therefore, pretreatment of liver donors with MP or its prodrug decreases KC activation by cold ischemia-reperfusion.

Prostaglandin E(1) protects human liver sinusoidal endothelial cell from apoptosis induced by hypoxia reoxygenation

Hepatic ischemia-reperfusion injury is an important cause of graft dysfunction after liver transplantation. Liver sinusoidal endothelial cells (LSECs) are particularly sensitive to ischemia-reperfusion injury and undergo apoptosis. This study investigates the protective role of PGE(1) on apoptosis of LSEC during hypoxia-reoxygenation in vitro. Hypothermia-hypoxia followed by reoxygenation triggered LSEC apoptosis, and prostaglandin PGE(1) protected LSEC from apoptosis in a dose-dependent manner. The release of matrix metalloproteinases (MMPs) and nitric oxide (NO) by LSECs were increased after hypoxia reoxygenation. Both the MMP inhibitor BB3103 and the NO inhibitor LNAM effectively decreased LSEC apoptosis, suggesting a separate role of MMPs and NO in hypoxia-reoxygenation-induced LSEC apoptosis. PGE(1) down-regulated NO production by inhibiting the expression of inducible NO synthase in LSEC. PGE(1) also inhibited MMP-2 release from LSEC during hypoxia reoxygenation. These results indicate that the protection of LSECs from apoptosis by PGE(1) in hepatic ischemia-reperfusion injury is mediated by inhibiting inducible NO synthase and MMP release.

One year follow-up of patients treated with misoprostol in acute phase of viral hepatitis B

The study was undertaken to determine the long-term effect of misoprostol, on hepatitis B virus (HBV) elimination in patients treated during acute phase of viral hepatitis B. Forty male patients were evaluated 12 months after treatment with misoprostol (M-group) or sylimarin (S-group). HBsAg clearance, as an indicator of HBV elimination, and serum bilirubin concentration, prothrombin index, and activities of alanine transaminase, aspartate transaminase, alkaline phosphatase as well as gamma glutamyltranspeptidase were analysed. At the end of treatment phase, improvement of liver function demonstrated through these biochemical indices was faster in M-group. After 12 months of follow-up HBsAg was cleared in all misoprostol treated patients and in 85% among S-group. Moreover misoprostol treatment resulted with normalization of bilirubin concentration and enzymes activity in all patients. Two among sylimarin treated patients (both HBsAg positive), had transaminases activities elevated over 100 U/l, that resulted with significantly higher values than in M-group. These results confirm beneficial effect of misoprostol treatment in patients with liver injury, but promising effect on HBV clearance should be confirmed in a study involving more patients.