Do splanchnic viscera contribute to liver preservation reperfusion injury?

Role of Dietary Nutritional Treatment on Hepatic and Intestinal Damage in Transplantation with Steatotic and Non-Steatotic Liver Grafts from Brain Dead Donors

Herein, we investigate whether: (1) the administration of glucose or a lipid emulsion is useful in liver transplantation (LT) using steatotic (induced genetically or nutritionally) or non-steatotic livers from donors after brain death (DBDs); and (2) any such benefits are due to reductions in intestinal damage and consequently to gut microbiota preservation. In recipients from DBDs, we show increased hepatic damage and failure in the maintenance of ATP, glycogen, phospholipid and growth factor (HGF, IGF1 and VEGFA) levels, compared to recipients from non-DBDs. In recipients of non-steatotic grafts from DBDs, the administration of glucose or lipids did not protect against hepatic damage. This was associated with unchanged ATP, glycogen, phospholipid and growth factor levels. However, the administration of lipids in steatotic grafts from DBDs protected against damage and ATP and glycogen drop and increased phospholipid levels. This was associated with increases in growth factors. In all recipients from DBDs, intestinal inflammation and damage (evaluated by LPS, vascular permeability, mucosal damage, TLR4, TNF, IL1, IL-10, MPO, MDA and edema formation) was not shown. In such cases, potential changes in gut microbiota would not be relevant since neither inflammation nor damage was evidenced in the intestine following LT in any of the groups evaluated. In conclusion, lipid treatment is the preferable nutritional support to protect against hepatic damage in steatotic LT from DBDs; the benefits were independent of alterations in the recipient intestine.

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.

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.

Gastro-intestinal complement activation during human liver transplantation: impact on postoperative liver function

BACKGROUND

Liver transplantation elicits a systemic inflammatory response and eventually a multiple organ failure syndrome. Gastro-intestinal inflammatory activation with release of proinflammatory cytokines and complement activation may occur. This study evaluates gastro-intestinal complement activation and the association with postoperative parenchymatous liver cell injury and liver dysfunction.

METHODS

In 17 patients undergoing liver transplantation, blood samples were collected from radial artery and portal vein for analysis of complement SC5b-9 and endotoxin concentration. Portal venous-arterial SC5b-9 plasma concentration gradients at 30 min after reperfusion were calculated. Outcome parameters included postoperative organ failure and serum concentrations of aspartate aminotransferase, alanine aminotransferase, bilirubin and factor II-VII-X.

RESULTS

Patients with gastro-intestinal SC5b-9 release (n=7) had higher postoperative serum aspartate aminotransferase and alanine aminotransferase concentrations [49 (32-80) microkat/l vs 8 (6-14) microkat/l, P<0.01 and 33 (15-54) microkat/l vs 8 (4-23) microkat/l, P<0.04, respectively] and lower factor II-VII-X concentrations [46 (21-48)% vs 60 (47-69)%, P<0.02] compared to patients without gastro-intestinal SC5b-9 release (n=10). The ICU stay was prolonged in patients with gastro-intestinal complement release. There was no difference in number of organ failures and serum bilirubin concentration between the groups. The endotoxin concentration in arterial and portal vein blood was low and the association between endotoxaemia and complement activation was poor.

CONCLUSION

Gastro-intestinal complement activation may contribute to postoperative parenchymatous liver cell injury and liver dysfunction in patients undergoing liver transplantation.

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.

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).

Rescue hepatectomy for initial graft non-function after liver transplantation

BACKGROUND

Early retransplantation is the therapy of choice in patients with initial graft nonfunction (INF). In rare cases the patients' conditions deteriorate dramatically with severe cardiovascular and/or pulmonary insufficiency while on the waiting list for retransplantation. In this life-threatening situation removal of the graft and temporary portocaval shunt before allocation of a new liver proved to be effective. Our experience with this two-stage hepatectomy and subsequent liver transplantation in patients with complicated INF is reported.

METHODS

Hepatectomy was performed in 20 patients with INF associated with severe cardiovascular and pulmonary insufficiency while on the waiting list for emergency liver retransplantation. The mean age was 41.75+/-16.64 years. The time period between primary transplantation and hepatectomy was 2.80+/-2.84 days with a range from 1 to 9 days.

RESULTS

Hepatectomy reduced the need for vasopressive agents and improved pulmonary function in the majority of patients. Four patients died before a liver was available due to brain death in one patient and multiorgan failure in three patients. In the remaining 16 patients liver transplantation could be performed after 19.82+/-15.34 hr (range 6.58 to 72.50 hr). Two of the 16 transplanted patients died on the first postoperative day due to multiorgan failure and pneumonia. The remaining 14 of 16 patients survived retransplantation, but 7 died between days 13 and 105 mostly due to sepsis. Seven patients were discharged from the hospital in good condition and show long-term survival.

CONCLUSION

Hepatectomy was able to stabilize the cardiovascular and pulmonary function. This study confirms the beneficial effects of hepatectomy and subsequent liver transplantation as a life-saving procedure in patients with INF complicated by cardiovascular and/or pulmonary instability.

Protective effect of ischemic preconditioning on liver preservation-reperfusion injury in rats

BACKGROUND

Ischemic-preconditioning is a process whereby a brief ischemic episode confers a state of protection against subsequent long-term ischemia-reperfusion injury. Ischemic preconditioning has been studied in heart and liver ischemia-reperfusion injury; however, few studies have been performed in the model of preservation-reperfusion injury in liver transplantation. The current study was designed to evaluate the ability of ischemic preconditioning to protect liver grafts from long-term preservation-reperfusion injury.

METHODS

Male Sprague Dawley rats were used as donors and recipients of orthotopic liver transplantation. Ischemic preconditioning was done by interruption of the portal vein and hepatic artery for 5, 10, and 20 min (5-10, 10-10, and 20-10 groups). Reflow was initiated by removal of the clamp for another 10 min in all groups. The liver was removed and placed in a bath with Euro-Collins solution for different preservation times. Tolerance of the transplanted liver to cold ischemia was determined by survival time and liver function tests. Rat tumor necrosis factor was analyzed by a bioassay. Nomega-Nitro-L-arginine methyl ester, L-arginine, or adenosine was administered to block or stimulate the synthesis of nitric oxide (NO) in the rats that received long-term-preserved liver grafts.

RESULTS

Twenty percent of syngeneic rats (n=10) that received a liver graft with a 16-hr cold ischemia time in Euro-Collins solution survived for more than 1 day and 10% survived for more than 5 days. In contrast, 87.5% of rats (n=8) that received a liver graft with ischemic preconditioning (10-10 group) and 16 hr of cold ischemia survived for more than 1 day and 75% for more than 5 days. Recipients of liver grafts with ischemic preconditioning had significantly reduced levels of serum aspartate transaminase and tumor necrosis factor-alpha, as well as increased bile flow, compared with recipients of liver grafts without ischemic preconditioning. Blockage of the NO pathway using Nomega-nitro-L-arginine methyl ester, a stereospecific competitive inhibitor of NO formation, attenuated the protective effect of ischemic preconditioning. Administration of one of two precursors of NO synthesis, L-arginine or adenosine, prolonged the survival of rats that received 16-hr-preserved liver grafts. In addition, L-arginine synergized with short-term ischemic pre conditioning (5-10 group) to increase the survival of rats that received a liver graft with a 16-hr cold ischemia time, and the survival rate was 83% after 5 days. Finally, prolonged ischemic preconditioning (> or = 20 min; 20-10 group) resulted in liver damage and loss of function.

CONCLUSION

The current results show that ischemic preconditioning protects the liver graft from subsequent long-term cold preservation-reperfusion injury in a rat liver transplantation model. The protective role of ischemic preconditioning may be mediated by the endogenous production of NO.