The Use of Prostaglandins in the Immediate Postsurgical Liver Transplant Period

Protective Role of Hepatocyte Cyclooxygenase-2 Expression Against Liver Ischemia-Reperfusion Injury in Mice

Liver ischemia and reperfusion injury (IRI) remains a serious clinical problem affecting liver transplantation outcomes. IRI causes up to 10% of early organ failure and predisposes to chronic rejection. Cyclooxygenase-2 (COX-2) is involved in different liver diseases, but the significance of COX-2 in IRI is a matter of controversy. This study was designed to elucidate the role of COX-2 induction in hepatocytes against liver IRI. In the present work, hepatocyte-specific COX-2 transgenic mice (hCOX-2-Tg) and their wild-type (Wt) littermates were subjected to IRI. hCOX-2-Tg mice exhibited lower grades of necrosis and inflammation than Wt mice, in part by reduced hepatic recruitment and infiltration of neutrophils, with a concomitant decrease in serum levels of proinflammatory cytokines. Moreover, hCOX-2-Tg mice showed a significant attenuation of the IRI-induced increase in oxidative stress and hepatic apoptosis, an increase in autophagic flux, and a decrease in endoplasmic reticulum stress compared to Wt mice. Interestingly, ischemic preconditioning of Wt mice resembles the beneficial effects observed in hCOX-2-Tg mice against IRI due to a preconditioning-derived increase in endogenous COX-2, which is mainly localized in hepatocytes. Furthermore, measurement of prostaglandin E₂ (PGE₂ ) levels in plasma from patients who underwent liver transplantation revealed a significantly positive correlation of PGE₂ levels and graft function and an inverse correlation with the time of ischemia. Conclusion: These data support the view of a protective effect of hepatic COX-2 induction and the consequent rise of derived prostaglandins against IRI.

Perioperative Care of the Liver Transplant Patient

With the evolution of surgical and anesthetic techniques, liver transplantation has become "routine," allowing for modifications of practice to decrease perioperative complications and costs. There is debate over the necessity for intensive care unit admission for patients with satisfactory preoperative status and a smooth intraoperative course. Postoperative care is made easier when the liver graft performs optimally. Assessment of graft function, vigilance for complications after the major surgical insult, and optimization of multiple systems affected by liver disease are essential aspects of postoperative care. The intensivist plays a vital role in an integrated multidisciplinary transplant team.

The Effect and Safety of Prostaglandin Administration in Pediatric Liver Transplantation

Background

Prostaglandins are often administered after liver transplantation (LT) to diminish ischemia-reperfusion injury (IRI), to favor liver recovery and to prevent vascular thrombosis. Possible beneficial effects in adult liver recipients are controversial, but the single existing pediatric small case series shows no significant impact of prostaglandin administration after LT. The purpose of this study was to analyze the effect of the prostaglandin dinoprostone in pediatric liver recipients.

Methods

A retrospective analysis of 41 children (<16 years) who underwent LT between March 2008 and December 2013 was performed. Dinoprostone was administered at a rate from 0.1 to a maximum of 0.6 μg/kg per hour immediately after LT and for a maximum of 5 days. Effect of dinoprostone on post-LT IRI and hepatic function up to 60 postoperative days and number of hypotensive episodes were analyzed.

Results

The median cumulative dose of dinoprostone was 28 μg/kg (interquartile range, 23.2). Dinoprostone had no significant effect on post-LT liver function tests and factor V levels at any of the administered dosages. There was no significant association between the total quantity of vasopressor given and the number of hypotensive episodes observed in 8 patients. One patient showed a short-lasting hypotension, possibly related to the administration of dinoprostone.

Conclusions

This study did not show, at any dosage between 0.1 and 0.6 μg/kg per hour, any differences in beneficial or harmful effects of high- or low-dose dinoprostone administered immediately after pediatric LT on markers of IRI, hepatic function, or hypotension.

Actual Risk of Using Very Aged Donors for Unselected Liver Transplant Candidates: A European Single-center Experience in the MELD Era

OBJECTIVE

To evaluate the whole experience of liver transplantation (LT) with donors ≥70 years in a single center not applying specific donor/recipient matching criteria.

BACKGROUND

LT with very old donors has historically been associated with poorer outcomes. With the increasing average donor age and the advent of Model for End-stage Liver Diseases (MELD) score-based allocation criteria, an optimal donor/recipient matching is often unsuitable.

METHODS

Outcomes of all types of LTs were compared according to 4 study groups: patients transplanted between 1998 and 2003 with donors <70 (group 1, n = 396) or ≥70 years (group 2, n = 88); patients transplanted between 2004 and 2010 with donors <70 (group 3, n = 409), or ≥70 years (group 4, n = 190). From 2003, graft histology was routinely available before cross-clamping, and MELD-driven allocation was adopted.

RESULTS

Groups 1 and 2 were similar for main donor and recipient variables, and surgical details. Group 4 had shorter donor ICU stay, lower rate of moderate-to-severe graft macrosteatosis (2.3% vs 8%), and higher recipient MELD score (22 vs 19) versus group 3. After 2003, median donor age, recipient age, and MELD score significantly increased, whereas moderate-to-severe macrosteatosis and ischemia time decreased. Five-year graft survival was 63.6% in group 1 versus 59.1% in group 2 (P = 0.252) and 70.9% in group 3 versus 67.6% in group 4 (P = 0.129). Transplants performed between 1998 and 2003, recipient HCV infection, balance of risk score >18, and pre-LT renal replacement treatments were independently associated with worse graft survival.

CONCLUSIONS

Even without specific donor/recipient matching criteria, the outcomes of LT with donors ≥70 and <70 years are comparable with appropriate donor management.

Impact of preoperative infection on outcome after liver transplantation

BACKGROUND

Bacterial infection in patients with liver failure can lead to a dramatic clinical deterioration. The indications for liver transplantation and outcome in these patients is still controversial.

METHODS

All adult patients who underwent liver transplantation between 1 January 2010 and 31 December 2015 were selected from an institutional database. Characteristics of the donors and recipients, and clinical, biochemical and surgical parameters were retrieved from the database. Post-transplant survival rates and complications, including grade III-IV complications according to the Dindo-Clavien classification, were compared between patients with an infection 1 month before transplantation and patients without an infection.

RESULTS

Eighty-four patients with an infection had statistically significant higher Model for End-stage Liver Disease (MELD), D-MELD and Balance of Risk (BAR) scores and a higher rate of acute-on-chronic liver failure compared with findings in 343 patients with no infection. The rate of infection after liver transplantation was higher in patients who had an infection before the operation: 48 per cent versus 30·6 per cent in those with no infection before transplantation (P = 0·003). The percentage of patients with a postoperative complication (42 versus 40·5 per cent respectively; P = 0·849) and the 90-day mortality rate (8 versus 6·4 per cent; P = 0·531) was no different between the groups. Multivariable analysis showed that a BAR score greater than 18 and acute-on-chronic liver failure were independent predictors of 90-day mortality.

CONCLUSION

Bacterial infection 1 month before liver transplantation is related to a higher rate of infection after transplantation, but does not lead to a worse outcome.

Effect of necrosis modulator necrox-7 on hepatic ischemia-reperfusion injury in beagle dogs

OBJECTIVE

The liver is susceptible to ischemia-reperfusion (IR) injury during inflow occlusion for hepatectomy. There is no effective pharmacologic agent available to prevent the release of high-mobility-group box 1 (HMGB1) or to ameliorate IR injury. This pilot study sought to develop a model in beagle dogs for the purpose of testing the efficacy of a necrosis modulator, necrox-7, to prevent hepatic IR injury in beagle dogs.

METHODS

Six male beagle dogs were randomly assigned to the control group (group A; n = 3) or the treatment group (group B; n = 3). Under general anesthesia, group B received intravenous infusion of necrox-7 (13 mg/kg over 20 minutes) followed by 60 minutes of left hepatic inflow occlusion and 60 minutes of reperfusion. Both groups were tested for serum biochemicals, hematology values, liver biopsies, and plasma HMGB1 levels over a 48-hour period.

RESULTS

The maximum alanine transferase (ALT), aspartate transferase (AST), and lactate dehydrogenase (LDH) levels among group A versus group B were: ALT 868.3 ± 337.4 IU/L vs 274.3 ± 72.6 IU/L (P = .041); AST 1,024.7 ± 246.5 IU/L vs 505.3 ± 66.7 IU/L (P = .024); and LDH 962.7 ± 226.2 IU/L vs 552.7 ± 62.4 IU/L (P = .039). Liver biopsy demonstrated marked necrosis and inflammatory infiltrates in group A, whereas group B showed little evidence of IR injury. The plasma HMGB1 concentration was significantly lower among group B versus A.

CONCLUSION

This pilot study developed a hepatic IR injury model, demonstrating that necrox-7 reduced hepatic necrosis secondary to IR injury in a large animal setting.

The hepatic microcirculation: mechanistic contributions and therapeutic targets in liver injury and repair

The complex functions of the liver in biosynthesis, metabolism, clearance, and host defense are tightly dependent on an adequate microcirculation. To guarantee hepatic homeostasis, this requires not only a sufficient nutritive perfusion and oxygen supply, but also a balanced vasomotor control and an appropriate cell-cell communication. Deteriorations of the hepatic homeostasis, as observed in ischemia/reperfusion, cold preservation and transplantation, septic organ failure, and hepatic resection-induced hyperperfusion, are associated with a high morbidity and mortality. During the last two decades, experimental studies have demonstrated that microcirculatory disorders are determinants for organ failure in these disease states. Disorders include 1) a dysregulation of the vasomotor control with a deterioration of the endothelin-nitric oxide balance, an arterial and sinusoidal constriction, and a shutdown of the microcirculation as well as 2) an overwhelming inflammatory response with microvascular leukocyte accumulation, platelet adherence, and Kupffer cell activation. Within the sequelae of events, proinflammatory mediators, such as reactive oxygen species and tumor necrosis factor-alpha, are the key players, causing the microvascular dysfunction and perfusion failure. This review covers the morphological and functional characterization of the hepatic microcirculation, the mechanistic contributions in surgical disease states, and the therapeutic targets to attenuate tissue injury and organ dysfunction. It also indicates future directions to translate the knowledge achieved from experimental studies into clinical practice. By this, the use of the recently introduced techniques to monitor the hepatic microcirculation in humans, such as near-infrared spectroscopy or orthogonal polarized spectral imaging, may allow an early initiation of treatment, which should benefit the final outcome of these critically ill patients.

Hepatoprotective effects of misoprostol and silymarin on carbon tetrachloride-induced hepatic damage in rats

The aim of this study was to investigate the effect of misoprostol, silymarin or the co-administration of misoprostol + silymarin on the carbon tetrachloride (CCl(4))-induced hepatic injury in rats. Misoprostol (10, 100, 1000 microg/kg), silymarin (25 mg/kg) or misoprostol (100 microg/kg) + silymarin (25 mg/kg) was given once daily orally simultaneously with CCl(4) and for 15 days thereafter. The results showed that misoprostol (10, 100 or 1000 microg/kg) conferred significant protection against the hepatotoxic actions of CCl(4) in rats, reducing serum alanine aminotransferase (ALT) levels by 24.7%, 42.6% and 49.4%, respectively compared with controls. Misoprostol, given at 100 or 1000 microg/kg, decreased aspartate aminotransferase (AST) by 28 and 43.6% and alkaline phosphatase (ALP) by 19.3% and 53.4% respectively. Meanwhile, silymarin reduced ALT, AST and ALP levels by 62.7%, 66.1% and 65.1% respectively. The co-administration of misoprostol (100 microg/kg) and silymarin (25 mg/kg) resulted in 61.4%, 66.1% and 57.5% reduction in ALT, AST and ALP levels respectively. Histopathological alterations and depletion of hepatocyte glycogen and DNA content by CCl(4) were markedly reduced after treatment with misoprostol, silymarin or misoprostol + silymarin. Image analysis of liver specimens revealed a marked reduction in liver necrosis; area of damage: 32.4%, 24% and 10.2% after misoprostol (10, 100 or 1000 microg/kg), 7.2% after silymarin and 10.9% after treatment with misoprostol 100 microg/kg + silymarin, compared with CCl(4) control group (46.7%). These results indicate that treatment with misoprostol protects against hepatocellular necrosis induced by CCl(4). This study suggests a potential therapeutic use for misoprostol in liver injury.