Tumor necrosis factor and endotoxin in the pathogenesis of liver and pulmonary injuries after orthotopic liver transplantation in the rat

Slow induction of brain death leads to decreased renal function and increased hepatic apoptosis in rats

Background

Donor brain death (BD) is an independent risk factor for graft survival in recipients. While in some patients BD results from a fast increase in intracranial pressure, usually associated with trauma, in others, intracranial pressure increases more slowly. The speed of intracranial pressure increase may be a possible risk factor for renal and hepatic graft dysfunction. This study aims to assess the effect of speed of BD induction on renal and hepatic injury markers.

Methods

BD induction was performed in 64 mechanically ventilated male Fisher rats by inflating a 4.0F Fogarty catheter in the epidural space. Rats were observed for 0.5, 1, 2 or 4 h following BD induction. Slow induction was achieved by inflating the balloon-catheter at a speed of 0.015 ml/min until confirmation of BD. Fast induction was achieved by inflating the balloon at 0.45 ml/min for 1 min. Plasma, kidney and liver tissue were collected for analysis.

Results

Slow BD induction led to higher plasma creatinine at all time points compared to fast induction. Furthermore, slow induction led to increased renal mRNA expression of IL-6, and renal MDA values after 4 h of BD compared to fast induction. Hepatic mRNA expression of TNF-α, Bax/Bcl-2, and protein expression of caspase-3 was significantly higher due to slow induction after 4 h of BD compared to fast induction. PMN infiltration was not different between fast and slow induction in both renal and hepatic tissue.

Conclusion

Slow induction of BD leads to poorer renal function compared to fast induction. Renal inflammatory and oxidative stress markers were increased. Liver function was not affected by speed of BD induction but hepatic inflammatory and apoptosis markers increased significantly due to slow induction compared to fast induction. These results provide initial proof that speed of BD induction influences detrimental renal and hepatic processes which could signify different donor management strategies for patients progressing to BD at different speeds.

Global consequences of liver ischemia/reperfusion injury

Liver ischemia/reperfusion injury has been extensively studied during the last decades and has been implicated in the pathophysiology of many clinical entities following hepatic surgery and transplantation. Apart from its pivotal role in the pathogenesis of the organ's post reperfusion injury, it has also been proposed as an underlying mechanism responsible for the dysfunction and injury of other organs as well. It seems that liver ischemia and reperfusion represent an event with “global” consequences that influence the function of many remote organs including the lung, kidney, intestine, pancreas, adrenals, and myocardium among others. The molecular and clinical manifestation of these remote organs injury may lead to the multiple organ dysfunction syndrome, frequently encountered in these patients. Remote organ injury seems to be in part the result of the oxidative burst and the inflammatory response following reperfusion. The present paper aims to review the existing literature regarding the proposed mechanisms of remote organ injury after liver ischemia and reperfusion.

Mechanisms of tumor necrosis factor-alpha and interleukin-6 induction during human liver transplantation

In human orthotopic liver transplantation (LTX) intraoperative elevations of TNF-α (> 100 pg/ml) and IL-6 (>800 pg/ml) have been found to correlate with early post-operative rejections and infections respectively. In this study the possible mechanism responsible for the induction of these cytokines has been investigated during liver allografting in 38 recipients. Intraoperative elevations of TNF-α (> 100 pg/ml) were detected in the majority of pre-transplant endotoxin positive recipients (8/12, > 10 endotoxin units/ml), the patients turning endotoxin positive until the end of grafting (3/5), and in a subgroup (6/21 patients), apparently endotoxin negative for the whole operation. Therefore endotoxin (ET) seems to stimulate release of TNF-α in approximately 50% of the patients, whereas sensitized Kupffer graft cells or immediate allograft reactivity of the host are likely to account for the remaining TNF-α positive cases. Elevations of IL-6 > 800 pg/ml) were found in approximately 50% of the TNF-α positive cases, indicating partially independent regulatory pathways for IL-6 induction in the TNF-α negative patients. In agreement with a previous study, 11/13 (85%) of the intraoperative TNF-α positive recipients rejected their grafts within the first 10 days post-operatively. These data demonstrate that ET/infection associated as well as ET independent/reperfusion associated intraoperative TNF-α elevations, promote the initiation of allograft rejection in human liver transplantation. The transient and low endotoxaemia caused by the liver grafting procedure performed without veno-venous bypass seems to be of minor importance in the intraoperative induction of TNF-α.

Inhibition of TNF-α protects against hepatic ischemia-reperfusion injury in rats via NF-κB dependent pathway

Hepatic ischemia-reperfusion injury (I/R) is a serious health problem associated with liver transplantation, resection surgery, and various types of shock especially hemorrhagic shock. In the present investigation, the effect of inhibition of tumor necrosis factor-alpha (TNF-α) using pentoxifylline or infliximab against hepatic I/R injury induced in rats by 45-min ischemia and 1-h reperfusion was studied. It was observed that both pentoxifylline and infliximab-treated groups showed a significantly lower extent and severity of liver injury. This is attributed to (1) a decrease in oxidative stress markers, (2) reduction of the expression of TNF-α, TNF-α type-1 receptors, and nuclear factor kappa B (NF-κB). Thus TNF-α inhibition may be one of the therapeutic interventions to overcome the deleterious effects of I/R on liver via reduction of oxidative stress and inhibition of inflammatory cascade.

Development of a porcine model of post-hepatectomy liver failure

BACKGROUND

The aim of this study was to develop a porcine model of post-operative liver failure (POLF) that could accurately reproduce all the neurological and metabolic parameters of the corresponding clinical syndrome that may develop after extensive liver resections.

METHODS

In our model, we induced POLF by combining extended left hepatectomy and ischemia of the small liver remnant of 150 min duration. Subsequently, the remnant liver parenchyma was reperfused and the animals were closely monitored for 24 h.

MATERIALS

Twelve Landrace pigs (weight 25-30 kg) were randomly assigned in two groups; eight of them constituted the experimental group, in which POLF was induced (POLF group, n = 8), whereas the rest of them (n = 4) were included in the control group (sham laparotomy without establishment of POLF). RESULTS (MEANS ± SD): All POLF animals gradually developed neurological and biochemical signs of liver failure including, among many other parameters, elevated intracranial pressure (24.00 ± 4.69 versus 10.17 ± 0.75, P = 0.004) and ammonia levels (633.00 ± 252.21 versus 51.50 ± 9.49, P = 0.004) compared with controls. Histopathologic evaluation of the liver at the end of the experiment demonstrated diffuse coagulative necrosis and severe architectural distortion of the hepatic parenchyma in all POLF animals.

CONCLUSION

Our surgical technique creates a reproducible porcine model of POLF which can be used to study the pathophysiology and possible therapeutic interventions in this serious complication of extensive hepatectomies.

Ex vivo transfer of nuclear factor-kappaB decoy ameliorates hepatic cold ischemia/reperfusion injury

Cold ischemia/reperfusion injury of the hepatic graft has been attributed to the release of various inflammatory cytokines. Specific inhibition of these cytokines may improve viability of the hepatic graft upon reperfusion. Herein we have assessed the efficacy of cis element decoy against nuclear factor-kappaB binding site delivery to the hepatic tissue in a rodent liver transplantation model. At 8 hours after reperfusion of the liver, significant reduction was noted in the livers treated with decoy in the release of cytosolic enzymes from the hepatocytes and in serum tumor necrosis factor alpha (P < .05). The neutrophilic infiltration into the hepatic grafts was significantly suppressed in the livers treated with decoy oligodeoxynucleotides (ODNs). Decoy ODNs against nuclear factor-kappaB binding site delivery improved the viability of the hepatic graft against cold ischemia/reperfusion injury in the rodent liver transplantation model.

Effects of amrinone in an experimental model of hepatic ischemia-reperfusion injury

BACKGROUND

During some surgical interventions, temporary occlusion of the hepatic blood supply may cause ischemia-reperfusion (IR) injury. Recent studies suggest that type 3 phosphodiesterase inhibitors may have a beneficial effect on liver IR injury. The aim of this study was to investigate whether amrinone, a type 3 phosphodiesterase inhibitor, could have a protective effect on liver having experimental liver IR injury.

MATERIALS AND METHODS

Sixty Wistar albino rats were randomly divided into three groups. The IR and amrinone groups were subjected to 1 h total hepatic ischemia, followed by 2 h of reperfusion. The sham group underwent midline laparotomy only. Amrinone 10 microg/kg/min was infused to the amrinone group during the 3 h of the IR period. Histopathological examination, biochemical liver function, and liver adenosine triphosphate concentration after reperfusion and survival rate on the seventh day after the IR insult were recorded.

RESULTS

Serum aspartate aminotransferase, alanine aminotransferase, lactic dehydrogenase levels, and histological damage scores in the amrinone and IR groups were significantly higher compared with the sham group (P < 0.01). However, all of these values were significantly lower in the amrinone group than in the IR group (P < 0.05). Liver adenosine triphosphate levels and the rat survival rate in the amrinone and IR groups were significantly lower than those in the sham group (P < 0.01). However, these values were significantly higher in the amrinone group compared to those in the IR group (P < 0.01).

CONCLUSIONS

These results suggest that amrinone plays a significant role in the protection of liver against IR injury and that this treatment may be a novel pharmacological agent for safe and efficient liver surgery.

Pentoxifylline inhibits liver expression of tumor necrosis factor alpha mRNA following normothermic ischemia-reperfusion

BACKGROUND

Pentoxifylline (PTX) has been shown to reduce hepatic injury after normothermic ischemia and reperfusion (I-R) in rat liver.

AIM

The aim of this study was to evaluate the effects of PTX on liver expression of tumor necrosis factor alpha (TNFalpha) mRNA following normothermic liver I-R.

MATERIALS AND METHODS

A segmental normothermic ischemia of the liver was induced in male Lewis rats by occluding the blood vessels including the bile duct to the median and left lateral lobes for 90 min. At the end of ischemia the nonischemic liver lobes were resected. Rats were divided into three groups: group 1, control Ringer lactate administration; group 2, PTX treatment; group 3, sham-operated control rats. PTX (50 mg/kg) was injected intravenously 30 min before and 60 min after induction of ischemia. Survival rates were compared and the serum activities of TNFalpha, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) were measured. Histology of the liver was assessed 6 h after reperfusion. Liver TNFalpha mRNA was assessed by PCR amplification at 0, 60, 120, and 210 min after reperfusion.

RESULTS

PTX treatment significantly increased 7 day survival (93.3%) compared with nontreated control rats (46.6%, p<0.007). The extent of liver necrosis and the release of liver enzymes were significantly decreased after PTX treatment. Serum activities of TNFalpha were significantly decreased and liver expression of TNFalpha mRNA was inhibited after PTX treatment.

CONCLUSION

PTX protects the liver from ischemic injury and inhibits liver expression of TNFalpha mRNA.

Graft Tumor Necrosis Factor Receptor-1 Protects After Mouse Liver Transplantation Whereas Host Tumor Necrosis Factor Receptor-1 Promotes Injury

BACKGROUND

Tumor necrosis factor (TNF)-alpha is a cytokine with pleiotropic effects on the liver. The predominant hepatic receptor for TNFalpha is TNF receptor-1 (TNFR1). TNFR1 mediates liver injury after ischemia/reperfusion but is also mitogenic during hepatic regeneration. This study investigated the role of graft and host TNFR1 in early graft injury after liver transplantation in mice.

METHODS

Livers from TNFR1 deficient (TNFR1-/-) and wild type (WT) mice were transplanted into either TNFR1-/- or WT recipients in all four possible combinations after 12 hours of cold storage. After eight hours, alanine transferase (ALT), necrosis, TdT-mediated dUTP-digoxigenin nick-end labeling (TUNEL) staining, caspase-3 activation, and myeloperoxidase were determined.

RESULTS

When TNFR1-/- livers were transplanted into either WT or TNFR1-/- recipients, ALT was twofold greater than when WT donor livers were used. Necrosis and TUNEL staining also increased twofold and sevenfold, respectively, after transplantation of TNFR1-/- donor livers compared to WT. By contrast, ALT and necrosis decreased when WT or TNFR1-/- livers were transplanted into TNFR1-/- hosts compared to WT, which was associated with decreased neutrophil infiltration.

CONCLUSION

In conclusion, graft and recipient TNFR1 has opposing effects. Graft TNFR1 decreases graft injury, whereas recipient TNFR1 mediates an increase of injury associated with enhanced neutrophil infiltration. Cross-transplanting of knockout and wild-type livers provides a new means to investigate graft-host interactions during hepatic injury.

Cold preservation of pig liver grafts with warm ischemia and pentoxifylline-UW solution

BACKGROUND

We undertook this study to investigate the safe time limits of cold preservation in UW solution of liver grafts subjected to warm ischemia (WI) for 20 min and the changes of the limits when pentoxifylline is added to UW solution.

METHODS

The safe time limit was studied in a simple porcine orthotopic liver transplantation (LTx) model. In donors, livers were subjected to 20 min of WI and subsequent 12-h (group 1, n = 5), 16-h (group 2, n = 5), and 20-h (group 3, n = 3) cold preservation in UW solution, respectively. After the safe time limits were clear, another group (group 4, n = 5) was built to test whether or not the limits can be changed when pentoxifylline is added to UW solution in an unsafe time limit group.

RESULTS

All five animals in group 1 survived up to 7 days of the survey endpoint. In group 2, only one animal survived up to the same survey endpoint and all animals in group 3 died within 12 h. The 1-week survival rate of group 1 was significantly higher than the other two groups. Group 1 had a lower level of alanine aminotransferase (ALT) or aspartase aminotransferase (AST) after LTx, less pathological damage, higher concentration of adenosine triphosphate (ATP) and higher microcirculation blood flux in the grafted liver tissue at 1 h after reperfusion than the other two groups. The results primarily showed that 12-h cold preservation was safe, 16 h was unsafe, and 20 h was highly unsafe. But when pentoxifylline was added to UW solution in cold preservation (16-h group, group 4), in contrast to group 2, the incidence of liver tissue necrosis and primary graft nonfunction was significantly lower in group 4 than in group 2. The 1-week survival rate of the pigs was 100% in the former and 20% in latter group. Levels of ALT and AST in recipients' artery blood, malondialdehyde and TNF-alpha concentration in grafted liver tissue, resistance of portal vein and hepatic artery after preservation in group 4 were significantly reduced, whereas microcirculation blood flux of the grafted liver, superoxide dismutase concentration and ATP concentration in grafted liver tissue were significantly elevated.

CONCLUSIONS

The safe time limit of cold preservation in UW solution of liver grafts subjected to WI for 20 min was about 12 h and the limits can be prolonged to 16 h when pentoxifylline is added to UW solution. Many mechanisms were involved.

Tumor necrosis factor-a antisense transfer remarkably improves hepatic graft viability

BACKGROUND

Cold ischemia/reperfusion injury of the hepatic graft, an unsolved problem in liver transplantations, is attributed to the release of inflammatory cytokines, especially the tumor necrosis factor- (TNF) alpha, from activated Kupffer cells (KC). Therefore, the specific inhibition of TNF-alpha could improve the viability of the hepatic graft upon reperfusion.

METHODS

We assessed the efficacy of TNF-alpha antisense (TNF-AS) oligodeoxynucleotides (ODNs) delivery to KC in a rodent liver transplantation model.

RESULTS

Seventy-one percent of the animals that received 6 hours preserved grafts in baths of lactated Ringer's solution (4 degrees C) and were treated with TNF-AS survived for over 14 days. Eighty percent of the animals treated with vehicle, sense ODNs, or balanced salt saline (BSS) died. Four hours after reperfusion of the liver, a significant reduction was noted in livers treated with TNF-AS in the release of cytosolic enzymes from the hepatocytes and the serum TNF-alpha (P<0.05). The expressions of TNF-alpha on KC and of intercellular adhesion molecule-1 on sinusoidal endothelial cells were completely suppressed in TNF-AS-treated livers.

CONCLUSIONS

TNF-AS delivery improves the viability of the hepatic graft, and this technique may solve hepatic graft nonfunction in a clinical setting.

Randomized trial comparing pulmonary alterations after conventional with venovenous bypass versus piggyback liver transplantation

During the anhepatic phase of conventional liver transplantation (LT), the inferior vena cava (IVC) is cross-clamped and venovenous bypass (VVB) is usually indicated for diversion of IVC and portal blood flow. VVB can theoretically lead to pulmonary complications due to the contact of the blood with the surfaces of the circuit. In the piggyback method, preservation of the IVC avoids VVB. The aim of this study is to compare pulmonary alterations after conventional with VVB versus piggyback LT. Sixty-seven patients were randomized for conventional VVB (n = 34) or piggyback (n = 33) LT. Pulmonary static compliance (C(st)) and Pa(O2)/F(IO2) ratio were measured pre- and post-LT. Chest X-rays were obtained daily from the 1st to the 5th postoperative day. Pre- and post-LT C(st) were 73.4 +/- 36.0 mL/cm H(2)O and 59.7 +/- 22.0 mL/cm H(2)O in the conventional group and 69.1 +/- 20.0 mL/cm H(2)O and 58.7 +/- 27.1 mL/cmH(2)O in the piggyback group. The difference between the two groups was not significant (P =.702). C(st) significantly decreased after LT (P =.008). The pre- and post-LT Pa(O2)/F(IO2) were 455.6 +/- 126.6 mm Hg and 463.1 +/- 105.9 mm Hg in the conventional group and 468.9 +/- 114.1 mm Hg and 483.3 +/- 119.8 mm Hg in the piggyback group. The difference among the two groups was not significant (P = 0.331). There was no significant difference after LT (P =.382). Upon the radiological evaluation, piggyback group presented a higher frequency of pulmonary infiltrates (80.6% vs. 50.0%; P =.025). In conclusion, piggyback LT recipients have a higher rate of pulmonary infiltrates when compared to those operated upon using the conventional VVB method.

Role of ischemic preconditioning and the portosystemic shunt in the prevention of liver and lung damage after rat liver transplantation

BACKGROUND

This study evaluates whether surgical strategies such as the portosystemic shunt and ischemic preconditioning can protect against hepatic and pulmonary injury associated with liver transplantation.

METHODS

The effect of the portosystemic shunt, ischemic preconditioning, and both surgical procedures together were evaluated in rat liver transplantation. Alanine aminotransferase, hyaluronic acid levels in plasma, adenosine triphosphate and nucleotide levels in liver and edema, malondialdehyde levels, and myeloperoxidase activity were measured 24 hr posttransplantation. Plasmatic tumor necrosis factor (TNF) levels were measured as a possible proinflammatory factor responsible for hepatic and pulmonary damage associated with liver transplantation.

RESULTS

Hepatocyte and cell endothelial damage were observed in liver grafts subjected to 8 hr of cold ischemia. This was associated with increased plasma TNF levels and lung inflammatory response. Portosystemic shunt application in the recipient protected endothelial cells but did not confer an effective protection from hepatocyte damage or reduce the increased plasma TNF levels and lung damage after liver transplantation. However, preconditioning of the donor liver conferred protection against both the endothelial cell and hepatocyte damage observed after liver transplantation. Preconditioning also attenuated the increased plasma TNF release and pulmonary damage. The combination of both surgical strategies resulted in levels of liver injury, TNF, and lung damage similar to those seen after liver transplantation.

CONCLUSIONS

These findings indicate that ischemic preconditioning could be a preferred treatment to reduce hepatic and pulmonary damage associated with liver transplantation. However, this strategy may not be effective in several clinical situations requiring a portosystemic shunt.

Endothelin-1 is involved in hepatic sinusoidal vasoconstriction after ischemia and reperfusion

Endothelin-1 (ET-1), a vasoactive peptide, causes a significant rise in portal vein pressure, which is most likely a result of severe vasoconstriction in the liver. In this study, the effect of ET-1 on sinusoidal vasoconstriction in the liver after ischemia and reperfusion was directly investigated using intravital microscopy. In anesthetized female Sprague Dawley rats (200-250 g) ischemia of the median and left liver lobes was induced for 90 min by temporary ligation of the left pedicle. After declamping and a 90-min reperfusion period, the livers were exposed for intravital microscopy. Using a Nikon MM-11 fluorescence microscope (545 nm, 330x), a CCD camera (Cohu FK 6990), and a SVHS video recording unit, the hepatic microcirculation was directly investigated. Besides sham groups, two ischemia groups were studied, receiving ET-1 antiserum (anti-ET-1; 0.5 ml; Peptide Inst., Osaka, Japan) or NaCl 0.9% (0.5 ml) 5 min prior to reperfusion of the liver (n = 6/group). Following a transient drop in the mean arterial blood pressure in the anti-ET-1-treated groups, comparable systemic hemodynamic conditions among the four groups were noted during intravital microscopic assessment at the end of the 90-min reperfusion period. Reduction in the sinusoidal diameters during postischemic reperfusion (7.7 +/- 0.5 microm) was prevented by anti-ET-1 treatment (9.6 +/- 0.25 microm; P < 0.01; mean + SEM) back to control values (9.6 +/- 0.32 microm), while most of other microcirculatory parameters did not show significant differences. The results supported further the role of ET-1 in dysregulation of the sinusoidal vascular tone in the liver, e.g., after ischemia and reperfusion.

Immunodepressants ameliorate normothermic ischemia injury to the rat liver by down-regulating tumor necrosis factor, not by alleviation of lipid peroxidative injury

Mechanisms by which immunodepressants (Cyclosporine, CsA; FK 506, FK; Azanthioprine, AZA) ameliorate warm ischemic injury of the liver were examined. Female Sprague-Dawley rats were subjected to 60-min of normothermic liver ischemia. Animals were assigned to one of four groups: group I, control with vehicle treatment; groups II, III, and IV, treatment with CsA (10 mg/kg), FK (1 mg/kg), and AZA (1 mg/kg), respectively. The immunosuppressive agents were given per os for 4 consecutive days prior to the induction of hepatic ischemia. In addition to a survival study, plasma levels of endotoxin, serum activities of tumor necrosis factor-alpha (TNF), plasma levels of phosphatidylcholine hydroperoxide (PCOOH) as a lipid peroxide, and serum alanine aminotransferase (ALT) were investigated in blood samples collected from the suprahepatic vena cava. A 7-day survival period was significantly higher in the immunosuppressed animals. Serum TNF levels were elevated and peaked at 3 h following reperfusion. When, the peak values were compared, the animals given immunodepressants had significantly lower levels of TNF (217.0 +/- 40.6 pg/ml for group I, 67.6 +/- 13.7 for group II, 87.9 +/- 28.3 for group III and 89.1 +/- 19.9 for group IV; Mean +/- SEM). Plasma PCOOH levels were also elevated following reperfusion, but with no statistical difference among the groups. Our data suggest that immunodepressants ameliorate warm ischemia/reperfusion injury through modulation of TNF production and not through a diminution of lipid peroxidative injury.

Ischemic preconditioning of rat livers against cold storage-reperfusion injury: role of nonparenchymal cells and the phenomenon of heterologous preconditioning

Brief periods of ischemia followed by reperfusion render tissues resistant against subsequent prolonged ischemia, a phenomenon called ischemic preconditioning. The effect of ischemic preconditioning on liver transplantation was investigated in relation to sinusoidal endothelial cell injury and Kupffer-cell activation, which are prominent features of storage and reperfusion injury leading to liver graft failure. Rat livers were preconditioned by 5 or 10 minutes of ischemia and 5 minutes of reperfusion and stored in University of Wisconsin (UW) solution for 30 hours. Livers were then reperfused for 15 minutes with physiological buffer containing trypan blue. Under these conditions, injury occurs predominantly to sinusoidal endothelial cells, reflected by trypan blue staining of nonparenchymal cells in histological sections. Ischemic preconditioning decreased nonparenchymal cell killing by more than 50%. When half the liver was preconditioned, sinusoidal endothelial cells were also protected in the contralateral half. Other stored livers were reperfused with nitroblue tetrazolium, which is converted to insoluble formazan by superoxide radicals. Ischemic preconditioning decreased the intensity of formazan deposition over Kupffer cells. Finally, stored livers were transplanted into nontreated rats. Ischemic preconditioning improved recipient long-term survival after 30 hours of cold ischemic storage in UW solution from 30% to 80% and decreased serum tumor necrosis factor-alpha levels in posthepatic blood 4 hours postoperatively from 98 to 54 pg/mL. In conclusion, ischemic preconditioning protects sinusoidal endothelial cells and suppresses Kupffer-cell activation after storage and reperfusion. As a result, graft survival improves after liver transplantation. Moreover, ischemia to half the liver confers protection to the other half. Such heterologous preconditioning provides a new means to protect liver tissue against ischemia-reperfusion injury without imposing ischemia on the target tissue.

Role of Kupffer cells in the survival after rat liver transplantation with long portal vein clamping times

Applying the orthotopic rat liver transplantation (ORLT) model, postoperative survival has been shown to be mainly dependent on the portal vein clamping time (PVCT). It was hypothesized that prolonged intestinal congestion was responsible for the activation of Kupffer cells (KC) with overproduction of TNF, secondary to splanchnic endotoxin accumulation and release on reperfusion. The role of KCs was directly investigated in the context of long PVCTs by eliminating them (using liposome-encapsulated dichloromethylene diphosphonate), by preventing their activation (using a calcium channel blocker, nisoldipine) and by inhibiting TNF production (using thalidomide). Livers from different groups of rats were transplanted following 24-h cold preservation in the UW solution with long PVCTs (from 18-21 min). KCs depletion, preservation with nisoldipine and pretreatment with thalidomide significantly improved survival in conditions using long PVCTs. KC depletion and nisoldipine preservation had no effect on liver enzymes or pathological findings while lung injury was significantly improved. The present data confirm that, in the context of ORLT with long PVCTs, KCs are directly responsible for the systemic endotoxin-like shock syndrome and their effect is mediated through overproduction of TNF.

Beneficial effect of FR167653 on cold ischemia/reperfusion injury in rat liver transplantation

BACKGROUND

Proinflammatory cytokines such as interleukin 1-beta (IL-1beta) and tumor necrosis factor-a (TNF-alpha) play an important role in the development of hepatic ischemia/reperfusion injury. FR167653 has been characterized as a potent suppressant of IL-1beta and TNF-alpha production. The aim of this study was to evaluate the effect of FR167653 on cold ischemia/ reperfusion injury in rat liver transplantation.

METHODS

Donor livers were preserved with cold University of Wisconsin solution for 48 hr and transplanted orthotopically. Immediately after reperfusion, FR167653 (1 mg/kg, FR-treated group) or normal saline solution (control group) was administered i.v.. The severity of liver injury was determined by hepatic enzyme levels as well as by histological findings. The accumulation of IL-1beta and TNF-alpha mRNA in the liver was analyzed by semi-quantitative reverse transcription-polymerase chain reaction. Tissue factor expression was subjected to immunohistochemical analysis.

RESULTS

In the FR-treated group, release of aspartate aminotransferase and alanine aminotransferase after reperfusion was significantly lower (P<0.05 and P<0.02, respectively), and histological liver injury was less prominent, than in the control group. Accumulation of IL-1beta and TNF-alpha mRNA was suppressed in the FR-treated liver. Tissue factor expression on Kupffer cells and sinusoidal endothelial cells, marked in the control group, was almost absent in the FR-treated group. Seven-day survival in the FR-treated group (75%) was significantly better than that in the control group (12.5%) (P<0.01).

CONCLUSIONS

These results indicate that treatment with FR167653 ameliorates cold ischemia/reperfusion injury in liver transplantation.

Atrial natriuretic peptide reduces expression of TNF-alpha mRNA during reperfusion of the rat liver upon decreased activation of NF-kappaB and AP-1

BACKGROUND/AIMS

The cardiovascular hormone Atrial Natriuretic Peptide (ANP) attenuates activation of the pro-inflammatory transcription factor NF-kappaB in macrophages. ANP was also shown to protect from ischemia-reperfusion injury of the rat liver. This study aimed to investigate the effects of this immunomodulatory hormone and its second messenger cGMP on the activation of the two redox-sensitive transcription factors AP-1 and NF-kappaB and the expression of corresponding pro-inflammatory target genes during ischemia and reperfusion of the liver. The identification of the mechanisms underlying the protection by ANP should reveal new aspects concerning the pathomechanisms of ischemia/reperfusion injury.

METHODS

Rat livers were perfused with and without ANP or 8-Br-cGMP preceding 24 h of cold storage in University of Wisconsin solution. During reperfusion NF-kappaB and AP-1 DNA binding activities were determined in freeze-clamped liver samples by electrophoretic mobility shift assay. Protein levels of p50, p65, and of IkappaB were determined by Western blot. mRNA coding for inducible nitric oxide synthase, cyclooxygenase-2, and TNF-alpha was determined by RT-PCR and Northern blot.

RESULTS

After 45 min of reperfusion DNA binding activities of NF-kappaB were increased, whereas in ANP pre-treated livers this effect was markedly reduced. AP-1, another important redox-sensitive transcription factor, was activated and in the course of reperfusion the subunit composition of AP-1 changed as assessed by supershift assays. ANP markedly reduced binding activities of both forms of AP-1. 8-Br-cGMP mimicked the effects of ANP on NF-kappaB and AP-1. Neither inducible nitric oxide synthase nor cyclooxygenase-2 mRNA could be detected. In contrast, a profound expression of transcripts coding for TNF-alpha was detected in the course of reperfusion and ANP markedly reduced TNF-alpha mRNA expression.

CONCLUSION

ANP seems to mediate its protective effect during ischemia and reperfusion by reducing the activation of NF-kappaB and AP-1 via cGMP. The reduced binding activity of these redox-sensitive transcription factors was accompanied by a diminished mRNA expression of TNF-alpha, a cytokine known to be involved in cellular damage in ischemia reperfusion injury.

Endotoxins and cytokines during liver transplantation: changes in plasma levels and effects on clinical outcome

Endotoxins, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), and IL-6 are believed to have a key role in liver transplantation. The origin and course of these factors is not completely known. In this prospective study of 40 patients, we sought more understanding of the relations between these factors and their effects on clinical outcome by sampling at different sites. Endotoxemia was only present in 20% of the patients. In 75% of these patients, it was present during the anhepatic phase and quickly resolved after reperfusion. Endotoxemia was not related to a clinical adverse event. TNF-alpha was released from the graft after reperfusion, and initial levels after reperfusion were related to predonation levels in the donor. Only levels of TNF-alpha in the recipient before transplantation were found to be predictive of postoperative complications. We conclude that monitoring endotoxins and these cytokines is of very limited value in predicting outcome.

Cold liver ischemia-reperfusion injury critically depends on liver T cells and is improved by donor pretreatment with interleukin 10 in mice

Kupffer cells are thought to mediate most of the deleterious effects of liver ischemia-reperfusion injury. The role of liver T cells and the impact of resident cell deactivation by interleukin 10 (IL-10) have never been addressed. Using a model of ex vivo liver cold ischemia and reperfusion, we assessed liver injury, tumor necrosis factor (TNF) and interferon gamma (IFN-gamma) release from livers of balb/c mice, nude mice, nude mice reconstituted with T cells, and gadolinium balb/c pretreated mice. The anti-inflammatory cytokine IL-10 was then used to define the best strategy of administration potentially able to modulate ischemia-reperfusion injury. For this purpose IL-10 was administered to the donor before liver harvesting, in the preservation medium during cold ischemia or during reperfusion. TNF and IFN-gamma were released time dependently and paralleled liver injury after reperfusion of cold preserved livers. Reperfused livers from nude or gadolinium pretreated mice disclosed a dramatic decrease in TNF and IFN-gamma release. Tissue injury was reduced by 51% in the absence of T cells and by 88% when Kupffer cells were deactivated. This effect was reverted by T-cell transfer to nude mice. Only donor pretreatment with IL-10 or IL-10 infusion during reperfusion led to a significant decrease in liver injury, TNF, and IFN-gamma release (-66% or -41%, -95% or -94%, and -70% or -70%, respectively). In conclusion, liver resident T cells are critically involved in cold ischemia-reperfusion injury and pretreatment of the donor with IL-10 decreases liver injury and the release of T-cell- and macrophage-dependent cytokines.

The portosystemic shunt protects liver against ischemic reperfusion injury

BACKGROUND

The goal of this study was to characterize the importance of splanchnic viscera in liver ischemic reperfusion injury and to enhance the tolerance of liver to warm ischemia injury with portosystemic shunt.

METHODS

The hepatic blood flow of male Sprague Dawley rats was subjected to 45, 60, 120, and 150 min liver warm ischemia with or without portosystemic shunt (splenic-caval shunt). The production of tumor necrosis factor a (TNFa), nuclear factor-kappaB activation, inducible NO synthase (iNOS) expression, and apoptosis were examined.

RESULTS

A total of 67% of rats with 45 min liver warm ischemia (n=6) and 100% of rats with 60 min liver warm ischemia (n=6) died within 1 day. However, all rats with 120 min (n=8) liver warm ischemia in splenic-caval shunt group survived for over 1 day, 6/8 for over 3 days, and 5/8 for over 5 days without significant histological changes of the liver. Serum tumor necrosis factor levels in liver warm ischemic rats were increased, This increase was significantly reversed after portosystemic shunt. After challenge with lipopolysaccharide (1 mg/kg, p.v.), naive rats survived for over 5 days (n=4) with the peak value of rat tumor necrosis factor (240 pg/ml) at 90 min. In contrast, all rats died within one day (n=5) with the peak value of rat tumor necrosis factor a (465 pg/ml) at 45 min after administration of lipopolysaccharide in the rats with liver warm ischemia plus splenic-caval shunt. iNOS expression and nuclear factor-kappaB activation were very strongly increased in the hepatocytes after liver warm ischemia with portosystemic shunt, compared with liver ischemia without portosytemic shunt.

CONCLUSIONS

We conclude that the splanchnic viscera can contribute to liver ischemic reperfusion injury. Portosystemic shunt enhances the tolerance of liver to warm ischemia through the protective role of iNOS and nuclear factor-kappaB (NF-kappaB).

Effect of specific neutrophil elastase inhibitor on ischemia/reperfusion injury in rat liver transplantation

Activated neutrophils have been implicated as playing an important role in ischemia/reperfusion injury of the liver by releasing toxic mediators such as oxygen free radicals and elastases. In the present study, we evaluated the effect of a novel, specific neutrophil elastase inhibitor (ONO-5046) on cold-ischemia/reperfusion injury of the liver allograft in rodents. Livers from male Lewis rats were procured and stored cold (4 degrees C) in lactated Ringer's solution and transplanted orthotopically. Recipients were divided into three groups: Vehicle group, 5-h preservation and vehicle (n = 8); ONO-5046 group, 5-h preservation and administration of ONO-5046 (n = 8); and Control group, minimum preservation only (n = 8). Bile output after reperfusion was significantly larger in the ONO-5046 group compared to the Vehicle group (P < 0.05 or less). Sinusoidal endothelial cell function represented by the serum hyaluronic acid concentration at 120 min after reperfusion of the ONO-5046 group was significantly lower than that in the Vehicle group (17.0 +/- 7.9 vs 36.2 +/- 14.9 ng/ml, P < 0.05), whereas serum transaminase levels 120 min after reperfusion were comparable between the two groups. Liver tissue energy charge 120 min after reperfusion was significantly better in the ONO-5046 group compared to the Vehicle group (P < 0.05). Furthermore, the number of neutrophils infiltrating the allograft after reperfusion was significantly depressed in the ONO-5046 group compared to the Vehicle group (P < 0. 02). These data suggest that the neutrophil elastase might cause liver damage early after reperfusion in cold-stored liver, which can be ameliorated by the administration of a specific neutrophil elastase inhibitor, ONO-5046.

Involvement of interleukin-18 (IL-18) in mixed lymphocyte reactions (MLR)

The in vitro mixed lymphocyte reaction (MLR) is a useful model to study alloresponsiveness to histocompatibility antigens. Secretion of different cytokine proteins in the supernatant of allo-MLR cultures has been reported in a few studies. We studied the levels of the cytokines interferon gamma (IFN-gamma) and interleukin-6 (IL-6), IL-10, IL-12, and IL-18 in the supernatant in allo-MLR by ELISA assay. Supernatant levels of IFN-y, IL-6, IL-10, and IL-18 were detected at 12 h after MLR and markedly increased thereafter. In contrast, secretion of IL-12 was detected after 48-72 h. These results suggested that IFN-gamma production depended on IL-18 in the early phase of MLR and depended on both IL-18 and IL-12 in the late phase. An antibody (Ab) neutralizing test was also performed. The levels of IFN-gamma were significantly downregulated after the addition of anti-IL-18 Ab, anti-IL-12 Ab, or anti-IFN-y Ab, and the levels of IL-12 were significantly downregulated after the addition of anti-IL-12 Ab and anti-IL-18 Ab. Treatment with these Ab did not suppress IL-6 production at all. The two-way MLR showed the same tendency as the one-way MLR. These results suggest the importance of IL-18 and IL-12 in allogeneic cell interactions and also suggest the usefullness of these Ab as regulators of alloresponsiveness.

Protection of sinusoidal endothelial cells against storage/reperfusion injury by prostaglandin E2 derived from Kupffer cells

BACKGROUND

In clinical liver transplants, grafts are frequently exposed to endotoxin (lipopolysaccharide, LPS) before harvest and may be predisposed to dysfunction. Because graft failure is linked to sinusoidal endothelial cell injury after storage/reperfusion, we investigated the effect of donor exposure to LPS on graft survival in relation to sinusoidal endothelial cell injury after storage/reperfusion in rats.

METHODS

Rats were injected with 0.5 mg/kg LPS. In some rats, 20 mg/kg GdCl3 or 5 mg/kg indomethacin was injected before LPS to ablate Kupffer cells and inhibit prostaglandin (PG) synthesis, respectively. Other rats were injected with 100 microg/kg dimethyl PGE2, a stable PGE2 analog. Rat livers were harvested, stored in cold UW solution and transplanted to non-treated rats for determination of survival and liver injury in recipients. Otherwise, after cold storage, the livers were reperfused briefly with physiological buffer containing trypan blue for determination of sinusoidal endothelial cell injury by counting trypan blue-positive nuclei in histological sections.

RESULTS

Donor treatment with LPS increased hepatic PGE2 production before storage and decreased recipient survival, but paradoxically decreased killing of sinusoidal endothelial cells after storage and reperfusion. Pretreatment of donors with GdCl3 or indomethacin prevented the protective preconditioning of sinusoidal endothelial cells by LPS, whereas pretreatment with dimethyl PGE2 protected sinusoidal endothelial cells to the same extent as LPS. Unlike LPS, however, PGE2 attenuated graft injury after liver transplants.

CONCLUSION

PGE2 derived from LPS-stimulated Kupffer cells protects sinusoidal endothelial cells against storage/reperfusion injury. Unlike LPS, PGE2 improves graft function after liver transplants. Thus, donor preconditioning with PGE2 may be beneficial in liver transplants.

Activation of nuclear factor-kappaB during orthotopic liver transplantation in rats is protective and does not require Kupffer cells

Reperfusion after liver transplantation results in the induction of tumor necrosis factor-alpha (TNFalpha) as well as activation of the stress-associated signaling proteins, c-Jun N-terminal kinase (JNK), activating protein-1 (AP-1), and nuclear factor-kappaB (NF-kappaB). To test the hypothesis that Kupffer cells are involved in the activation of signal transduction cascades during rat liver transplantation, Kupffer cells were depleted from donor liver using gadolinium chloride (GdCl3), and then the activation of JNK, AP-1, and NF-kappaB were assessed after transplantation. The results showed that GdCl3 treatment did not inhibit the activation of these stress signals, although transplanted livers were depleted of Kupffer cells and partially protected from reperfusion injury. Interleukin-6 (IL-6) and IL-10 messenger RNAs (mRNAs) were induced by transplantation, and the induction was suppressed by Kupffer cell depletion. The induction of TNFalpha mRNA and serum protein during liver transplantation was unaffected by GdCl3. These results show that Kupffer cells are not a major source of TNFalpha production after liver transplantation and that stress-signaling protein activation occurs independently of Kupffer cells. Transplantation strongly activates the transcription factor NF-kappaB, which blocks TNFalpha-mediated apoptosis in hepatocytes in vitro. To assess the role of NF-kappaB activation during liver transplantation, the IkappaBalpha superrepressor was expressed in donor livers using adenoviral-mediated gene transfer. Inhibition of NF-kappaB resulted in increased serum alanine aminotransferase levels after 3 hours of transplantation. In addition, the blockade of NF-kappaB resulted in increased histological tissue injury and increased hepatic terminal deoxyribonucleotide transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) staining, indicating apoptosis. These results show that NF-kappaB activation has a protective role in the transplanted liver.

Tumor necrosis factor increases mitochondrial oxidant production and induces expression of uncoupling protein-2 in the regenerating mice [correction of rat] liver

The growth-stimulatory actions of tumor necrosis factor alpha (TNF-alpha) after partial hepatectomy (PH) are difficult to reconcile with its well-established role in the genesis of liver injury. The lethal actions of TNF are thought to involve the induction of oxidant production by mitochondria. It is not known if TNF initiates mitochondrial oxidant production after PH. Furthermore, if this potentially toxic response follows PH, it is not clear how hepatocytes defend themselves sufficiently so that replication, rather than death, occurs. These studies test the hypothesis that TNF does increase mitochondrial oxidant production after PH but that these oxidants primarily promote the induction of antioxidant defenses in regenerating hepatocytes. Consistent with this concept, H2O2 production by liver mitochondria increases from 5 minutes to 3 hours after PH, beginning before the transient inductions of hepatic NF kB activity (which peaks at 30 minutes post-PH) and uncoupling protein-2 (UCP-2) (which begins around 30 minutes and peaks from 6-24 hours post-PH). Pretreatment with neutralizing anti-TNF antibodies, which inhibits hepatocyte DNA synthesis after PH, also reduces post-PH hepatic mitochondrial oxidant production by 80% and inhibits NF kappaB activation and UCP-2 induction by 50% and 80%, respectively. In contrast, pretreatment with D609, an agent that inhibits phosphatidylcholine-specific phospholipase C, neither inhibits regenerative induction of mitochondrial oxidant production, UCP-2 expression, nor hepatocyte DNA synthesis, although it inhibits NF kappaB activation by 50%. Given published evidence that NF kappaB is antiapoptotic and that UCP-2 may decrease mitochondrial oxidant production in some cells, these results suggest that TNF-dependent increases in oxidant production by liver mitochondria promote the induction of antioxidant defenses in the regenerating liver.

Expression of tumor necrosis factor-alpha gene during allograft rejection following rat liver transplantation

BACKGROUND/AIMS

Tumor necrosis factor-alpha (TNF-alpha) is believed to play a role in hepatic allograft rejection. However, the specific cellular population responsible for TNF-alpha production during hepatic allograft rejection is not known. Circulating monocyte-macrophage cells are the primary systemic sources of TNF-alpha. In the liver, Kupffer cells are the main producers of TNF-alpha. In this study, we determined which cells are involved in TNF-alpha production during allograft rejection after orthotopic liver transplantation.

METHODS

In situ hybridization was used to identify cells with TNF-alpha mRNA in the liver. Immunohistochemical staining with ED2 and ED3 was used to differentiate between cellular types (Kupffer cells versus infiltrating monocytes). To detect DNA fragmentation in liver cells, TdT-mediated biotin-dUTP nick-end labeling (TUNEL) was done. Studies were performed in the rat liver transplant model using rejecting (ACI to LEW) and non-rejecting (ACI to ACI) donor/recipient combinations.

RESULTS

In the control group, cells with TNF-alpha mRNA were rarely observed. In the rejection group, TNF-alpha mRNA was observed in mononuclear cells that were mainly within the vessels of the portal region and occasionally in the sinusoids. The cells with the signals for TNF-alpha mRNA were ED2-negative and ED3-positive. DNA fragmentation was observed in hepatocytes as well as infiltrating mononuclear cells.

CONCLUSIONS

The main producer of TNF-alpha may be infiltrating mononuclear cells such as monocyte-macrophage cells rather than Kupffer cells during allograft rejection after liver transplantation. Circulating monocyte-macrophages may play a role in the control of allograft rejection.

Improvement of normothermic rat liver ischemia/reperfusion by muramyl dipeptide

Normothermic ischemia and reperfusion (I/R) of the liver remains a major problem after liver surgery and transplantation. Activation of Kupffer cells (KCs) after normothermic I/R is responsible for a massive release of various monokines such as tumor necrosis factor alpha (TNF-alpha) and a decrease in phagocytic activity. Muramyl dipeptide (MDP) is an immunostimulant that increases phagocytic activity of KCs. The aim of this study was to demonstrate that MDP pretreatment might protect the liver against I/R injury by a modification of KC functions. Rats were divided into three groups: group 1, control, Ringer's lactate administration; group 2, MDP (N-acetyl-muramyl-d-alanyl-d-isoglutamine) treatment; group 3, sham-operated control animals. MDP (500 microg/250 g) was injected intravenously 5 min before the induction of 90 min ischemia. Survival rates were compared and serum activities of TNF-alpha, aspartate aminotransferase, and alanine aminotransferase were assessed in the blood collected from the suprahepatic vena cava. Histology of the liver and KC activity were assessed 6 and 9 h after the end of ischemia, respectively. MDP treatment significantly increased 7-day survival (86.6%) compared with nontreated rats (40%, P < 0.001). Serum activities of TNF-alpha and aminotransferases were significantly decreased after MDP treatment, whereas phagocytic capacity of KCs was partially restored. The extent of liver necrosis was decreased after MDP administration. A significant difference was observed for other histological parameters studied, except for steatosis. Our findings have demonstrated that MDP is able to protect the liver from ischemic insult by modulation of KC activity (TNF-alpha release and phagocytic capacity). Control of macrophage activity may offer a new strategy to reduce ischemic injury of the liver.

Decreased survival in rat liver transplantation with extended cold preservation: role of portal vein clamping time

Primary liver graft dysfunction is currently related to cold ischemia-reperfusion injury, although a wide survival range has been reported using 24-hour preservation in cold University of Wisconsin (UW) solution. We hypothesized that the portal vein clamping time (PVCT) played a more important role than cold preservation injury in the postoperative outcome. Rat liver transplantation was performed using different clamping times after 24-hour cold ischemia in the UW solution. Survival rates, plasma tumor necrosis factor (TNF), and nitrate/nitrite levels were examined. Subsequently, the effect of clamping time was evaluated on hepatocyte and sinusoidal endothelial cell (SEC) function using isolated perfused livers. Survival rate was directly related to clamping time length. Marked increases in TNF and nitrate/nitrite levels were found after surgery, particularly after long clamping times. In perfusion studies, the SEC function was already markedly altered after preservation alone and was not further modified by transplantation. By contrast, the hepatocyte function was moderately altered after transplantation, irrespective of clamping times, even when rats operated with long clamping times were in terminal conditions. In rats, 24-hour preservation in cold UW solution is not a severely compromising condition leading to primary liver nonfunction. Long PVCTs are associated with an endotoxemia-like syndrome more related to a warm intestinal ischemia than to cold ischemia injury of the liver.

S-adenosylmethionine deficiency and TNF-alpha in lipopolysaccharide-induced hepatic injury

S-adenosylmethionine (Adomet) is a substrate for de novo synthesis of choline. Adomet deficiency occurs in certain types of liver injury, and the injury is attenuated by exogenous Adomet. Tumor necrosis factor-alpha (TNF-alpha) is also a mediator of these models of hepatotoxicity. We investigated the role of Adomet in lipopolysaccharide (LPS)-induced liver injury in rats made deficient in both Adomet and choline. Rats were maintained on either a methionine-restricted and choline-deficient (MCD) diet or a diet containing sufficient amounts of all nutrients [methionine and choline sufficient (MCS)] and then administered either LPS or saline. MCS-LPS rats had normal liver histology and no change in serum transaminases compared with the MCS-saline control group. MCD-saline rats had hepatosteatosis but no necrosis, and a five- to sevenfold increase in transaminases vs. the MCS-saline group. MCD-LPS rats additionally had hepatonecrosis and a 30- to 50-fold increase in transaminases. Exogenous Adomet administration to MCD-LPS rats corrected the hepatic deficiency of Adomet but not of choline, prevented necrosis but not steatosis, and attenuated transaminases. Serum TNF-alpha was sixfold higher in MCD rats even without LPS challenge and 300-fold higher with LPS challenge. Exogenous Adomet attenuated increased serum TNF-alpha in MCD-LPS rats.

Selective bowel decontamination of recipients for prevention against liver injury following orthotopic liver transplantation: evaluation with rat models

Gut-derived substances can activate Kupffer cells to provoke hepatic necrosis after partial hepatectomy in rats. A similar situation may occur during orthotopic liver transplantation (OLT), as congestion in the intestinal wall, caused by portal vein occlusion, is inevitable during the operation. The contribution of such substances to liver injury following OLT was investigated in rats. Oral administration of polymyxin B sulfate for 7 days significantly altered intestinal bacterial flora in rats; Enterobacteriaceae diminished and anaerobes such as Bifidobacterium , Lactobacillus, Bacteroides, and Eubacterium increased in number, compared with the control rats. Also, this treatment significantly reduced endotoxin concentration in the portal blood 30 minutes after blood reflow following portal vein occlusion. When OLT was performed in rats using the liver preserved in cold University of Wisconsin solution for 18 hours, tissue factor activity in Kupffer cells (KC) isolated from the transplanted liver 1 hour after the operation was significantly higher than in that of normal rats. This increase was significantly reduced by pretreatment of the recipients with polymyxin B sulfate. In these recipients, serum alanine aminotransferase activity, tumor necrosis factor alpha (TNF alpha) concentration, and histological extent of liver necrosis were significantly attenuated at 24 hours after the operation compared with those of control rats. We conclude that the substances derived from bacilli sensitive to polymyxin B sulfate in the gut may be a contributing factor to liver injury following OLT in rats; we feel that this probably occurs by entering of the substances into the portal blood during the ahepatic phase of the operation to activate KC. Selective bowel decontamination of recipients with polymyxin B sulfate would be a candidate for protection against early graft failure following OLT.

Efficiency of pentoxifylline in donor pretreatment in rat liver transplantation

Donor pretreatment is a new concept in organ preservation. Pentoxifylline (PTX) has been reported to suppress the activation of Kupffer cells and to decrease injury to the hepatic graft after rat liver transplantation. We evaluated the efficiency of PTX pretreatment on the donor against hepatic injury following cold ischemia (CI) or warm ischemia (WI) using the rat liver transplantation model. Dose dependency: every rat was injected intraperitoneally with PTX (30, 50, or 80 mg/kg) or saline. One hour later, the portal vein (PV) and the hepatic artery (HA) were clamped for 30 min. Transplantation: the donor rat was injected intraperitoneally with 50 mg/kg PTX or saline, 1 hr before laparotomy. Animals were divided into two groups. In the CI group, grafts were preserved for 12 hr in University of Wisconsin solution at 4 degrees C and transplanted. In the WI group, the PV and the HA in the donor were clamped for 30 min before donor surgery, and the grafts were transplanted. Serum levels of tumor necrosis factor-alpha (TNF-alpha), glutathione S-transferase-alpha (GST-alpha), and aspartate transaminase (AST) were measured at 30 min, 3 hr, and 24 hr after reperfusion of the PV. Compared with those of a control group, the serum levels of TNF-alpha, GST-alpha, and AST in the PTX-pretreated groups were significantly lower after both CI and WI at 30 min and further suppressed in the WI group at 24 hr. These results indicate that PTX pretreatment on the donor is effective for suppression of hepatic injury after both CI and WI.

Reperfusion injury after liver preservation for transplantation

Preservation injury remains an obstacle to greater utilization of liver transplantation therapy. Livers can be preserved a maximum of 24 h in University of Wisconsin solution. After longer times, reperfusion precipitates endothelial cell killing and activation of Kupffer cells (liver macrophages). Together, Kupffer cell activation and endothelial cell killing cause microcirculatory disturbances, leukocyte and platelet adhesion, and a systemic inflammatory response after graft implantation. Down-regulation of Kupffer cells with calcium blockers or pentoxifylline improves graft survival, whereas priming with lipopolysaccharide or alcohol worsens survival. Flushing grafts after storage with Carolina rinse solution containing antioxidants, adenosine, calcium blocker, energy substrates, and glycine at pH 6.5 decreases endothelial cell killing, reduces Kupffer cell activation, and improves graft survival. Understanding of the roles of different cells in storage/reperfusion injury forms the basis for strategies to prolong organ storage, improve graft function, and reduce failure of fatty grafts from alcoholic donors.

The beneficial effect of the prostacyclin analogue (OP 2507) on rat liver transplantation subjected to an extended anhepatic phase

We investigated the effect of a prostacyclin analogue (OP 2507) on PVG (RT1c) recipients subjected to an extended anhepatic phase (AH) and transplanted orthotopically with PVG livers. All of the animals that underwent orthotopic liver transplantation (OLT) with a 20-min AH survived for 1 week with or without OP 2507, (OP) treatment (10/10, 100%). When the AH was lengthened to 45 min, the 1-week survival rate of recipients was poor in the OP-untreated groups (1/10, 10%). Treatment of the recipient with OP 2507, 0.15 micrograms/kg per minute for 30 min, prior to the 45-min AH substantially improved 1-week survival (5/6, 83.3%, P < 0.05). The serum TNF-alpha level at day 1 in OP-treated animals that underwent OLT with a 45-min AH was significantly lower than that in animals with 45-min AH OLT without OP treatment. We conclude that OP 2507 treatment has potential usefulness as a perioperative treatment when the AH is extended during OLT.

Early graft loss secondary to massive hemorrhagic necrosis following orthotopic liver transplantation. Evidence for cytokine-mediated univisceral Shwartzman reaction

Massive hemorrhagic necrosis (MHN) of the liver following orthotopic liver transplantation (OLT) occurs infrequently during an otherwise uneventful recovery 1 week after OLT. It is characterized by fever and sudden deterioration of allograft function leading to failure in the absence of vascular thrombosis. The etiology is unknown, although it is usually preceded by some degree of allograft rejection. Between 6 and 8 days after OLT, four patients (out of 150) became febrile, hypotensive, and experienced a rapid rise in transaminases within 48 hr. Two patients had evidence of mild rejection; the other two had moderate to severe acute cellular rejection. All patients were ABO identical, crossmatch negative. Bolus steroids were given followed by OKT3 in the two patients with severe rejection. Although sepsis was suspected, antibiotic therapy did not ameliorate the clinical course. Each patient progressed to MHN with severe centrilobular necrosis and variable portal infiltrate. High levels of interferon-gamma and tumor necrosis factor-alpha occurred prior to the rise in transaminases in each MHN patient (155 +/- 39 pg/ml and 414 +/- 201 pg/ml, respectively) compared with levels in OLT patients with severe rejection (14 +/- 4 pg/ml and 26 +/- 5 pg/ml, respectively, P < 0.05). These data support the concept of a cytokine-mediated inflammatory response leading to a univisceral Shwartzman reaction in the transplanted liver. Early recognition of this syndrome and retransplantation are critical for survival.

The F(ab')2 fragment of an anti-ICAM-1 monoclonal antibody attenuates liver injury after orthotopic liver transplantation

Long-term storage of liver grafts results in increased adhesion of leukocytes onto the sinusoidal walls. This eventually leads to posttransplant graft damage through disturbances of hepatic microcirculation. Intracellular adhesion molecule-1 (ICAM-1) is known to be involved in attachment of leukocytes. This study was designed to examine whether ICAM-1 participated in the pathogenesis of posttransplant liver injury. Inbred Lewis rats were used as both donors and recipients to avoid immunoreactivity. Donor livers were stored for either 1 or 6 hr in ice-cold Euro-Collins solution and subsequently implanted. Expression of ICAM-1 was examined immunohistochemically. In some rats that received livers stored for 6 hr, the intact IgG (1.0 mg/kg) or the F(ab')2 fragment (0.5 mg/kg) of an anti-ICAM-1 mAb (1A29) was administered via the tail vein immediately after reperfusion of portal blood. In the group receiving livers stored for 6 hr, ICAM-1 began to be expressed on the sinusoidal endothelial cells as early as 15 min after reperfusion of the portal blood. Strong ICAM-1 expression was observed from 2 hr up to 24 hr after reperfusion. In contrast, expression of ICAM-1 was not evident at any time point after surgery in the 1-hr storage group as well as in untransplanted, normal livers. Serum alanine aminotransferase (ALT) levels were significantly higher in the 6-hr storage group compared with those of the 1-hr storage group (1-hr: 171 +/- 9 IU/L; 6-hr: 825 +/- 109 IU/L, P < 0.05; mean +/- SEM) 24 hr after transplantation. Serum ALT levels were markedly reduced by treatment with the F(ab')2 fragment of 1A29 (247 +/- 34 IU/L, P < 0.05 vs. 6-hr storage group). This was associated with reduced accumulation of leukocytes in the liver. In marked contrast, treatment with the intact IgG of 1A29 increased serum ALT levels dramatically (5297 +/- 634 IU/L, P < 0.05 vs. 6-hr storage group) and reduced serum complement. Histological examination revealed focal hepatocellular necrosis 24 hr after surgery in the 6-hr storage group. Treatment with the F(ab')2 fragment decreased the liver damage; in marked contrast, treatment with the intact IgG strikingly aggravated the injury, as characterized by massive necrosis throughout the liver. Liver damage caused by the intact IgG might be related to activation of the complement system by the Fc portion of the antibody. Taken together, these results indicate that ICAM-1 is involved in the mechanism of postoperative liver injury following liver transplantation.