Ischemic preconditioning vs adenosine vs prostaglandin E1 for protection against liver ischemia/reperfusion injury

The Effect of Pringle Maneuver Applied during Living Donor Hepatectomy on the Ischemia-Reperfusion Injury Observed in the Donors and Recipients

Background and Objectives: The aim of this study is to evaluate the clinical and laboratory changes of ischemia and reperfusion injury in the remnant livers of donors with and without Pringle maneuver. Furthermore, we evaluated the recipients who have been transplanted with liver grafts from these donors. Methods and Materials: A total of 108 patients (54 living liver donors and 54 liver recipients) who underwent donor hepatectomy and recipients who living donor liver transplantation, were included in this randomized double-blind study between February 2021 and June 2021. The donors were divided into two groups: Pringle maneuver applied (n = 27) and Pringle maneuver not applied (n = 27). Similarly, recipients with implanted liver obtained from these donors were divided into two groups as the Pringle maneuver was performed (n = 27) and not performed (n = 27). Blood samples from donors and recipients were obtained on pre-operative, post-operative 0 h day (day of surgery), post-operative 1st day, post-operative 2nd day, post-operative 3rd day, post-operative 4th day, post-operative 5th day, and liver tissue was taken from the graft during the back table procedures. Liver function tests and complete blood count, coagulation tests, IL-1, IL-2, IL-6, TNF-α, and β-galactosidase measurements, and histopathological findings were examined. Results: There was no statistically significant difference in the parameters of biochemical analyses for ischemia-reperfusion injury at all periods in the donors with and without the Pringle maneuver. Similarly, there was no statistically significant difference between in the recipients in who received liver grafts harvested with and without the Pringle maneuver. There was no statistically significant difference between the two recipient groups in terms of perioperative bleeding and early bile duct complications (p = 0.685). In the histopathological examinations, hepatocyte damage was significantly higher in the Pringle maneuver group (p = 0.001). Conclusions: Although the histological scoring of hepatocyte damage was found to be higher in the Pringle maneuver group, the Pringle maneuver did not augment ischemia-reperfusion injury in donors and recipients that was evaluated by clinical and laboratory analyses.

Prostaglandins for adult liver transplanted recipients

BACKGROUND

Prostaglandins are naturally occurring lipids that are synthesised from arachidonic acid. Multiple studies have evaluated the benefits of prostaglandins in reducing ischaemia reperfusion injury after liver transplantation. New studies have been published since the previous review, and hence it was important to update the evidence for this intervention.

OBJECTIVES

To evaluate the benefits and harms of prostaglandins in adults undergoing liver transplantation compared with placebo or standard care.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 27 December 2022.

SELECTION CRITERIA

We included randomised clinical trials evaluating prostaglandins initiated in the perioperative period compared with placebo or standard care for adults undergoing liver transplantation. We included trials irrespective of reported outcomes.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were 1. all-cause mortality, 2. serious adverse events, and 3. health-related quality of life. Our secondary outcomes were 4. liver retransplantation, 5. early allograft dysfunction, 6. primary non-function of the allograft, 7. acute kidney failure, 8. length of hospital stay, and 9. adverse events considered non-serious. We used GRADE to assess certainty of evidence.

MAIN RESULTS

We included 11 randomised clinical trials with 771 adult liver transplant recipients (mean age 47.31 years, male 61.48%), of whom 378 people were randomised to receive prostaglandins and 393 people were randomised to either placebo (272 participants) or standard care (121 participants). All trials were published between 1993 and 2016. Ten trials were conducted in high- and upper-middle-income countries. Prostaglandins may reduce all-cause mortality up to one month (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.61 to 1.23; risk difference (RD) 21 fewer per 1000, 95% CI 63 fewer to 36 more; 11 trials, 771 participants; low-certainty evidence). Prostaglandins may result in little to no difference in serious adverse events (RR 0.92, 95% CI 0.60 to 1.40; RD 81 fewer per 1000, 95% CI 148 fewer to 18 more; 6 trials, 568 participants; low-certainty evidence). None of the included trials reported health-related quality of life. Prostaglandins may result in little to no difference in liver retransplantation (RR 0.98, 95% CI 0.49 to 1.96; RD 1 fewer per 1000, 95% CI 33 fewer to 62 more; 6 trials, 468 participants; low-certainty evidence); early allograft dysfunction (RR 0.62, 95% CI 0.33 to 1.18; RD 137 fewer per 1000, 95% CI 241 fewer to 47 more; 1 trial, 99 participants; low-certainty evidence); primary non-function of the allograft (RR 0.58, 95% CI 0.26 to 1.32; RD 23 fewer per 1000, 95% CI 40 fewer to 16 more; 7 trials, 624 participants; low-certainty evidence); and length of hospital stay (mean difference (MD) -1.15 days, 95% CI -5.44 to 3.14; 4 trials, 369 participants; low-certainty evidence). Prostaglandins may result in a large reduction in the development of acute kidney failure requiring dialysis (RR 0.42, 95% CI 0.24 to 0.73; RD 100 fewer per 1000, 95% CI 132 fewer to 49 fewer; 5 trials, 477 participants; low-certainty evidence). The evidence is very uncertain about the effect of prostaglandins on adverse events considered non-serious (RR 1.19, 95% CI 0.42 to 3.36; RD 225 fewer per 1000, 95% CI 294 fewer to 65 fewer; 4 trials, 329 participants; very low-certainty evidence). Two trials reported receiving funding; one of these was with vested interests. We found one registered ongoing trial.

AUTHORS' CONCLUSIONS

Eleven trials evaluated prostaglandins in adult liver transplanted recipients. Based on low-certainty evidence, prostaglandins may reduce all-cause mortality up to one month; may cause little to no difference in serious adverse events, liver retransplantation, early allograft dysfunction, primary non-function of the allograft, and length of hospital stay; and may have a large reduction in the development of acute kidney injury requiring dialysis. We do not know the effect of prostaglandins on adverse events considered non-serious. We lack adequately powered, high-quality trials evaluating the effects of prostaglandins for people undergoing liver transplantation.

Combined administration of membrane-permeable and impermeable iron-chelating drugs attenuates ischemia/reperfusion-induced hepatic injury

BACKGROUND

The underlying pathophysiological mechanisms of hepatic ischemia-reperfusion (I/R) injury have not been completely elucidated. However, it is well known that oxidative stress, caused by a burst of reactive oxygen species (ROS) production during the reperfusion phase, plays a crucial role. A growing body of evidence indicates that the intracellular availability of free iron represents a requirement for ROS-induced adverse effects, as iron catalyzes the generation of highly reactive free radicals. The aim of this study was to examine whether a combination of iron chelators with varying lipophilicity could offer enhanced protection against I/R by diminishing the conversion of weak oxidants, like H₂O₂, to extremely reactive ones such as hydroxyl radicals (HO^.).

METHODS

HepG2 cells (hepatocellular carcinoma cell line) were exposed to oxidative stress conditions after pre-treatment with the iron chelators desferrioxamine (DFO) and deferiprone (DFP) alone or in combination. Labile iron pool was estimated using the calcein-acetoxymethyl ester (calcein-AM) method and DNA damage with the comet assay. We subsequently used a rabbit model (male New Zealand white rabbits) of hepatic I/R-induced injury to investigate, by measuring biochemical (ALT, ALT, ALP, γGT) and histological parameters, whether this may be true for in vivo conditions.

RESULTS

The combination of a membrane-permeable iron chelator (DFP) with a strong membrane-impermeable one (DFO) raises the level of protection in both hepatic cell lines exposed to oxidative stress conditions and hepatic I/R rabbit model.

CONCLUSIONS

Our results show that combinations of iron chelators with selected lipophilicity and iron-binding properties may represent a valuable strategy to protect against tissue damage during reperfusion after a period of ischemia.

Exogenous Adenosine Antagonizes Excitatory Amino Acid Toxicity in Primary Astrocytes

Excitatory toxicity is still a hot topic in the study of ischemic stroke, and related research has focused mainly on neurons. Adenosine is an important neuromodulator that is known as a "biosignature" in the central nervous system (CNS). The protective effect of exogenous adenosine on neurons has been confirmed, but its mechanism remains elusive. In this study, astrocytes were pretreated with adenosine, and the effects of an A2a receptor (A2aR) inhibitor (SCH58261) and A2b receptor (A2bR) inhibitor (PSB1115) on excitatory glutamate were investigated. An oxygen glucose deprivation/reoxygenation (OGD/R) and glutamate model was generated in vitro. Post-model assessment included expression levels of glutamate transporters (glt-1), gap junction protein (Cx43) and glutamate receptor (AMPAR), Na+-K+-ATPase activity, and diffusion distance of dyes. Glutamate and glutamine contents were determined at different time points. The results showed that (1) adenosine could improve the function of Na+-K+-ATPase, upregulate the expression of glt-1, and enhance the synthesis of glutamine in astrocytes. This effect was associated with A2aR activation but not with A2bR activation. (2) Adenosine could inhibit the expression of gap junction protein (Cx43) and reduce glutamate diffusion. Inhibition of A2aR attenuated adenosine inhibition of gap junction intercellular communication (GJIC) in the OGD/R model, while it enhanced adenosine inhibition of GJIC in the glutamate model, depending on the glutamate concentration. (3) Adenosine could cause AMPAR gradually entered the nucleus from the cytoplasm, thereby reducing the expression of AMPAR on the cell membrane. Taken together, the results indicate that adenosine plays a role of anti-excitatory toxicity effect in protection against neuronal death and the functional recovery of ischemic stroke mainly by targeting astrocytes, which are closely related to A2aR. The present study provided a scientific basis for adenosine prevention and ischemic stroke treatment, thereby providing a new approach for alleviating ischemic stroke.

TAK242 suppresses the TLR4 signaling pathway and ameliorates DCD liver IRI in rats

Ischemia-reperfusion injury (IRI) is a notable cause of tissue damage during surgical procedures and a major risk factor in graft dysfunction in liver transplantation. Livers obtained from donors after circulatory death (DCD) are prone to IRI and toll-like receptor 4 (TLR4) serves a prominent role in the inflammatory response associated with DCD liver IRI. The present study was designed to investigate whether TAK242, a specific TLR4 inhibitor, improves hepatic IRI following a DCD graft and to investigate its underlying protective mechanisms. Male Sprague-Dawley rats were randomized into 4 groups: Control, TAK242, DCD and DCD+TAK242 groups. Rats were pretreated with TAK242 or its vehicle for 30 min, then the livers were harvested without warm ischemia (control group and TAK242 group) or with warm ischemia in situ for 30 min. The livers were stored in cold University of Wisconsin solution for 24 h and subsequently perfused for 60 min with an isolated perfused rat liver system. Rat liver injury was evaluated thereafter. When compared with the DCD group, DCD livers with TAK242 pretreatment displayed significantly improved hepatic tissue injury and less tissue necrosis (P<0.05). Compared with DCD livers, mechanistic experiments revealed that TAK242 pretreatment alleviated mitochondrial dysfunction, reduced reactive oxygen species and malondialdehyde levels and inhibited apoptosis. Additionally, TAK242 significantly inhibited the IRI-associated inflammatory response, indicated by the decreased expression of TLR4, interleukin (IL)-1β, IL-6 and cyclooxygenase 2 at the mRNA and protein levels (P<0.05). TAK242 ameliorates DCD liver IRI via suppressing the TLR4 signaling pathway in rats. The results of the present study have revealed that TAK242 pretreatment harbors a potential benefit for liver transplantation.

Ischemia With Preconditioning in Wistar Rats Maintains Mitochondrial Respiration, Even With Mild Hepatocellular Disturbance

INTRODUCTION

In hepatectomy or liver transplantation, preconditioning is a procedure indicated to protect the organ from ischemia-reperfusion injury (I-R).

OBJECTIVE

Evaluate the effect of preconditioning after hepatic I-R in Wistar rats, through mitochondrial respiration, liver histology, and profile.

METHOD

Twenty male Wistar rats, weighing on average 307.1 g, were anesthetized with sodium thiopental (25 mg/kg) intravenously and xylazine hydrochloride (30 mg/kg) intramuscularly. The animals were divided into 2 groups: the preconditioning group (PCG), which contained 10 animals, and the hepatic pedicle was isolated and submitted to clamping with microvascular clamp (10 minutes of ischemia and 10 minutes of reperfusion, followed by 30 minutes of ischemia and 30 minutes of reperfusion); and the simulated operation group (SOG), which contained 10 animals submitted to manipulation of the hepatic pedicle and observation for the same length of time, with blood collected for transaminase dosage measurements, and liver biopsy for evaluation of mitochondrial respiration and histologic liver analysis and after sacrificed under anesthesia. The project was approved by the Ethics Committee on Animal Experimentation CEEA/UNICAMP under protocol number 3905-1.

RESULT

The PCG mitochondria showed the same respiration level as the SOG, when stimulated with the addition of adenosine diphosphate or carbonyl cyanide p-trifluoromethoxyphenylhydrazone. In the respiratory control ratio and resting of velocity of respiration the groups behaved in a similar way. The PCG presented high aspartate and alanine transaminases (P < .03) and about 60% of sinusoidal congestion and venous congestion in the histologic analysis when compared with SOG.

CONCLUSION

We found that ischemia with preconditioning in Wistar rats can lead to mild histologic and biochemical dysfunction without leading to impairment of mitochondrial respiration.

Prostaglandin E1 Preconditioning Attenuates Liver Ischemia Reperfusion Injury in a Rat Model of Extrahepatic Cholestasis

The aim of this study is to explore the hepatoprotective effect of intraportal prostaglandin E1 (PGE1) on liver ischemia reperfusion (IR) injury using an extrahepatic cholestatic model, observing oxidative stress markers, proinflammatory factors, apoptotic marker proteins, and an adhesion molecule. The extrahepatic cholestatic model was induced by common bile duct ligation. After seven days, rats were subjected to ischemia by Pringle maneuver for 15 min, followed by 1, 6, or 24 h of reperfusion. Prostaglandin E1 (PGE group) or normal saline (NS group) was continuously infused from 15 min before liver ischemia to 1 h after reperfusion. After reperfusion, histopathological evaluation of the liver was performed, as were measurements of bilirubin, biochemical enzymes, oxidative stress markers (GSH and MDA), proinflammatory factors (MPO, TNF-α, and IL-1β), apoptotic marker proteins (Bcl-2 and Bax), and the adhesion molecule (ICAM-1). PGE1 pretreatment attenuated IR injury in extrahepatic cholestatic liver probably by suppressing MDA, MPO, TNF-α, IL-1β, ICAM-1, and Bax levels and improving GSH and Bcl-2 levels. In conclusion, PGE1 protects extrahepatic cholestatic liver from IR injury by improving hepatic microcirculation and reducing oxidative stress damage, intrahepatic neutrophil infiltration, and hepatocyte apoptosis.