Molecular biology of liver ischemia/reperfusion injury: established mechanisms and recent advancements

Preventive Effect of Antioxidative Nutrient-Rich Enteral Diet Against Liver Ischemia and Reperfusion Injury

BACKGROUND

Liver ischemia and reperfusion injury (IRI) is a major problem associated with liver surgery. This study is aimed to compare the preventive effect of an antioxidative nutrient-rich enteral diet (Ao diet) with an ordinal enteral diet (control diet) against liver IRI.

METHODS

The Ao diet was an ordinary diet comprising polyphenols (catechin and proanthocyanidin) and enhanced levels of vitamins C and E. Male C57BL/6 mice were fed the Ao or control diet for 7 days before ischemic insult for 60 minutes, followed by reperfusion for 6 hours. The levels of inflammatory cytokines, chemokines, and antioxidant enzymes and oxidative stress were evaluated.

RESULTS

After 7 days of pretreatment with the Ao diet, the serum levels of vitamins C and E in mice were markedly elevated. The levels of serum aspartate aminotransferase and alanine aminotransferase, as well as the scores of liver necrosis caused by ischemia and reperfusion, were significantly lower in the Ao diet group than in the control diet group. The gene expression levels of inflammatory cytokines and chemokines, such as interleukin-6 and CXCL1, were significantly lower in the Ao diet group. In the liver, the levels of antioxidant enzymes superoxide dismutase 1 (SOD1) and SOD2 were significantly higher and the malondialdehyde levels were significantly lower in the Ao diet group. Cell adhesion molecule expression was significantly lower, and neutrophil and macrophage infiltration was less in the Ao diet group.

CONCLUSIONS

Antioxidative nutrient supplementation to an ordinary enteral diet may mitigate liver IRI by causing an antioxidant effect and suppressing inflammation.

Hypothermic machine perfusion attenuates ischemia/reperfusion injury against rat livers donated after cardiac death by activating the Keap1/Nrf2‑ARE signaling pathway

Hypothermic machine perfusion (HMP) has been demonstrated to be a more effective method for preserving livers donated after circulatory death (DCD) than cold storage (CS); however, the underlying mechanisms remain unclear. The aim of the present study was to investigate the protective effects of HMP on rat DCD livers and the possible role of the nuclear factor erythroid 2‑related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway. A total of 18 adult male rats were randomly divided into three groups: Control, HMP and CS (n=6 per group). To simulate the conditions of DCD liver transplantation, rat livers in the CS and HMP groups were subjected to 30 min warm ischemia following cardiac arrest and were then preserved by CS or HMP for 3 h. Subsequently, after 1 h of isolated reperfusion, the extent of ischemia/reperfusion injury (IRI) and cellular functions were assessed. During reperfusion, intrahepatic resistance and bile production were measured, and the perfusion fluid was collected for liver enzyme analysis. The liver tissues were then harvested for the assessment of malondialdehyde (MDA) production, superoxide dismutase (SOD) activity, ATP levels, as well as for histological analysis, immunohistochemistry and a terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Finally, the expression levels of the components associated with the Nrf2‑ARE signaling pathway were analyzed via western blotting and reverse transcription‑quantitative polymerase chain reaction. The results of the present study revealed that, compared with in the CS group, the HMP group exhibited higher levels of ATP, bile production and SOD activity, and improved histological results; however, lower levels of liver enzymes, apoptosis and MDA were detected. Additionally, the findings of the present study also suggested that the Nrf2‑ARE signaling pathway may be activated by the steady laminar flow of HMP. In conclusion, HMP may attenuate ischemia‑reperfusion injury to rat DCD livers via activation of the Nrf2‑ARE signaling pathway.

S-Adenosylmethionine attenuates bile duct early warm ischemia reperfusion injury after rat liver transplantation

Warm ischemia reperfusion injury (IRI) plays a key role in biliary complication, which is a substantial vulnerability of liver transplantation. The early pathophysiological changes of IRI are characterized by an excessive inflammatory response. S-Adenosylmethionine (SAM) is an important metabolic intermediate that modulates inflammatory reactions; however, its role in bile duct warm IRI is not known. In this study, male rats were treated with or without SAM (170 μmol/kg body weight) after orthotopic autologous liver transplantation. The histopathological observations showed that bile duct injury in the IRI group was more serious than in the SAM group. The alanine aminotransferase (ALT), alkaline phosphatase (ALP) and direct bilirubin (DBIL) levels in the serum of the IRI group were significantly increased compared to the SAM group (P < .05). Simultaneously, SAM effectively improved the survival of the transplant recipients. Furthermore, the H₂O₂ and malondialdehyde (MDA) of the IRI group were much higher compared to the SAM group (P < .05). The GSH/GSSG ratio in the SAM group was significantly increased by SAM treatment compared to the IRI group (P < .05). SAM administration significantly inhibited macrophage infiltration in liver and bile duct tissues, down-regulated TNF-α levels and up-regulated IL-10 expression in bile duct tissues compared to the IRI group (P < .05). The number of apoptotic biliary epithelial cells and caspase-3-positive cells in IRI rat livers were much higher compared to those in SAM-treated rats at 24 h after liver transplantation (P < .05). These data suggested that SAM protected bile ducts against warm IRI by suppressing oxidative stress, inflammatory reactions and apoptosis of biliary epithelial cells after liver transplantation.α.

A comprehensive review on regulatory effects of crocin on ischemia/reperfusion injury in multiple organs

Ischemia-reperfusion (I/R) injury affects o₂-dependent organs including liver, kidneys, heart, brain, and intestine. I/R injury is described as the cellular injury in an organ caused by ischemia and then further aggravated during the reperfusion due to intracellular alterations. It is a process that happens in clinical settings such as organ transplantation, reperfusion after thrombolytic therapy, and coronary angioplasty. Crocus sativus L. known as saffron used in folk medicine for its beneficial effects. It contains multiple bioactive compounds including the crocin, crocetin, picrocrocin, and safranal. Crocin, a water-soluble carotenoid has antitumor, radical scavenging, anti hyperlipidemia and memory improving effects. Moreover, crocin has antioxidant, and protective effects on I/R models in rats at various organs such as heart, brain, kidney, stomach, liver, and kidney as described in detail in this review.

Recent insights into mitochondrial targeting strategies in liver transplantation

Ischemia/reperfusion (I/R) injury in liver transplantation can disrupt the normal activity of mitochondria in the hepatic parenchyma. This potential dysfunction of mitochondria after I/R injury could be responsible for the initial poor graft function or primary nonfunction observed after liver transplantation. Thus, determining the mechanisms that lead to human hepatic mitochondrial dysfunction might contribute to improving the outcome of liver transplantation. Furthermore, early identification of novel prognostic factors involved in I/R injury could serve as a key endpoint to predict the outcome of liver grafts and also to promote the early adoption of novel strategies that protect against I/R injury. Here, we briefly review recent advances in the study of mitochondrial dysfunction and I/R injury, particularly in relation to liver transplantation. Next, we highlight various pharmacological therapeutic strategies that could be applied, and discuss their relationship to relevant mitochondrion-related processes and targets. Lastly, we note that although considerable progress has been made in our understanding of I/R injury and mitochondrial dysfunction, further investigation is required to elucidate the cellular and molecular mechanisms underlying these processes, thereby identifying biomarkers that can help in evaluating donor organs.

Morphological alterations and redox changes associated with hepatic warm ischemia-reperfusion injury

AIM

To study the effects of warm ischemia-reperfusion (I/R) injury on hepatic morphology at the ultrastructural level and to analyze the expression of the thioredoxin (TRX) and glutaredoxin (GRX) systems.

METHODS

Eleven patients undergoing liver resection were subjected to portal triad clamping (PTC). Liver biopsies were collected at three time points; first prior to PTC (baseline), 20 min after PTC (post-ischemia) and 20 min after reperfusion (post-reperfusion). Electron microscopy and morphometry were used to study and quantify ultrastructural changes, respectively. Additionally, gene expression analysis of TRX and GRX isoforms was performed by quantitative PCR. For further validation of redox protein status, immunogold staining was performed for the isoforms GRX1 and TRX1.

RESULTS

Post-ischemia, a significant loss of the liver sinusoidal endothelial cell (LSEC) lining was observed (P = 0.0003) accompanied by a decrease of hepatocyte microvilli in the space of Disse. Hepatocellular morphology was well preserved apart from the appearance of crystalline mitochondrial inclusions in 7 out of 11 patients. Post-reperfusion biopsies had similar features as post-ischemia with the exception of signs of a reactivation of the LSECs. No changes in the expression of redox-regulatory genes could be observed at mRNA level of the isoforms of the TRX family but immunoelectron microscopy indicated a redistribution of TRX1 within the cell.

CONCLUSION

At the ultrastructural level, the major impact of hepatic warm I/R injury after PTC was borne by the LSECs with detachment and reactivation at ischemia and reperfusion, respectively. Hepatocytes morphology were well preserved. Crystalline inclusions in mitochondria were observed in the hepatocyte after ischemia.

Protective effects of crocin and zinc sulfate on hepatic ischemia-reperfusion injury in rats: a comparative experimental model study

OBJECTIVES

The aim of this study was to investigate the comparative protective effects of separate and combined pretreatment with Cr and ZnSO4 on serum levels of miR-122, miR-34a, liver function tests, protein expression of Nrf2 and p53, and histopathological changes following IR-induced hepatic injury.

MATERIALS AND METHODS

Fifty-six male Wistar rats randomly assigned into seven groups (n=8). Sham (S), IR, crocin pretreatment (Cr), and crocin pretreatment+IR (Cr+IR), ZnSO4 pretreatment (ZnSO4), ZnSO4 pretreatment+IR (ZnSO4+IR) and their combination (Cr+ZnSO4+IR) groups. In sham, ZnSO4 and Cr groups, animals received normal saline (N/S, 2ml/day), Cr (200mg/kg) and ZnSO4 (5mg/kg) for 7 consecutive days (intraperitoneally; i.p), then only laparotomy was performed. In IR, Cr+IR, ZnSO4+IR and Cr+ZnSO4+IR groups, rats received N/S, Cr and ZnSO4 with same dose and time, then underwent a partial (70%) ischemia for 45min that followed by reperfusion for 60min. Blood sample was taken for biochemical and microRNAs assay, tissue specimens were obtained for antioxidants, protein expression, histopathological and immunohistochemical evaluations.

RESULTS

The results showed that Cr and ZnSO4 increased antioxidants activity and expression of Nrf2, decreased serum levels of liver enzymes, miR-122, miR-34a, p53 expression and also ameliorated histopathological abnormality. However, their combination caused more improvement on IR-induced liver injury.

CONCLUSION

This study demonstrated that Cr, ZnSO4 and their combination through increasing antioxidant activity and Nrf2 expression, decreasing the serum levels of liver enzymes, miR-122, 34a, p53 expression, and amelioration of histopathological changes, protected liver against IR-induced injury.

Hepatocellular uptake of cyclodextrin-complexed curcumin during liver preservation: A feasibility study

The increasing demand for donor organs and the decreasing organ quality is prompting research toward new methods to reduce ischemia reperfusion injury (IRI). Several strategies have been proposed to protect preserved organs from this injury. Before curcumin/dextrin complex (CDC), a potent antioxidant and anti-inflammatory agent, can be used clinically we need to better understand the intracellular uptake under hypothermic conditions on a rat model of liver donation after circulatory death (DCD) and brain death (DBD). To be able to use the fluorescence of CDC for quantification the stability of CDC in different preservation solutions at 4°C or 37°C was investigated. Livers from Wistar rats were procured after being flushed-out through the portal vein using CDC-enriched preservation solutions and stored at 4°C for variable periods. The CDC signal was stable in different preservation solutions over a period of 4 h and allowed the rapid and lasting uptake of curcumin into cells. After 4 h of preservation, CDC was no longer visible microscopically, and HPLC analysis showed very low to non-detectable tissue levels of CDC, proving metabolization during preservation. However, the distribution of CDC was not affected by warm ischemia damage (p = 0.278) nor by flushing the livers before or after 4 h of cold storage and without a warm preflush. Finally, curcumin reduced oxidative stress, lowered histological injury and did not change gene expression after WI/cold storage. Therefore, the use of CDC flush solution for the initial organ flush can offer a promising approach to the enhancement of liver preservation and the maintenance of its quality.

The liver protection of propylene glycol alginate sodium sulfate preconditioning against ischemia reperfusion injury: focusing MAPK pathway activity

Hepatic ischemia reperfusion (IR) injury contributes to the morbidity and mortality associated with liver surgery. This study investigated the protective function and mechanism of propylene glycol alginate sodium sulfate (PSS), a sulfated polysaccharide, in a mouse hepatic IR injury model. PSS (25 or 50 mg/kg) or saline were injected intraperitoneally to male Balb/c mice 1 h before 45 min of 70% warm hepatic ischemia and 2, 8, and 24 h of reperfusion. Serum and liver tissue samples were collected for evaluation of hepatocellular damage, liver histology, and assay of inflammatory cytokines, apoptosis- and autophagy-related proteins, and proteins in the mitogen-activated protein kinase (MAPKs). Histological injury and release of transaminases, and inflammatory cytokine production were significantly reduced by PSS pretreatment. The expression of apoptosis- and autophagy-related proteins, and the activation of MAPK signal, including jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and P38 were all affected by PSS treatment compared with IR model controls. PSS protected the liver from IR injury by suppressing the MAPK signaling and down-regulating inflammation, apoptosis, and autophagy.

Mechanical reperfusion with leucocyte-filtered blood does not prevent injury following global cerebral ischaemia

Objectives

Prolonged global cerebral ischaemia leads to irreversible injury, often with lethal outcome. Brain injuries are partly caused by the uncontrolled reperfusion that occurs once the circulation is re-established. Recent animal experiments suggest that controlled reperfusion following lengthy ischaemia might prevent severe brain injury. This study aimed at further exploring cerebral alterations and outcome following prolonged global cerebral ischaemia and mechanically manipulated reperfusion.

Methods

Three groups of pigs were included; one sham operated ( n  = 3) and two that underwent 30-min global cerebral ischaemia. All vessels that supply the brain were isolated intrathoracically, after which they were occluded for 30 min in the ischaemic groups. In one of the ischaemic groups uncontrolled reperfusion was applied (URep, n  = 6), i.e. normal circulation was restored 30 min after arrested cerebral circulation. The second ischaemic group received mechanical reperfusion (MRep, n  = 6) with leucocyte-filtered blood at constant flow and pressure for 20 min using extracorporeal circulation following the 30-min ischaemia, after which normal blood flow resumed. All animals were monitored for 3 h after start of uncontrolled reperfusion. Haemodynamic parameters, arterial and sagittal sinus blood gases, cerebral oxygen extraction rates and intraparenchymal biomarkers using microdialysis were measured. Brain histology was performed post-mortem.

Results

Global brain ischaemia led to the same extent of severe morphological changes at the level of light microscopy in the two ischaemic experimental groups, regardless of reperfusion protocol. Furthermore, no significant differences were found between the URep and MRep groups regarding cerebral blood gases or microdialysis biomarkers.

Conclusions

Mechanical reperfusion following the current protocol does not modify brain alterations caused by 30 min of arrested cerebral circulation.

Asiatic acid protects against hepatic ischemia/reperfusion injury by inactivation of Kupffer cells via PPARγ/NLRP3 inflammasome signaling pathway

Hepatic ischemia/reperfusion (I/R) contributes to major complications in clinical practice affecting perioperative morbidity and mortality. Recent evidence suggests the key role of nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammaosme activation on the pathogenesis of I/R injury. Asiatic acid (AA) is a pentacyclic triterpene derivative presented with versatile activities, including antioxidant, anti-inflammation and hepatoprotective effects. This study was designed to determine whether AA had potential hepatoprotective benefits against hepatic I/R injury, as well as to unveil the underlying mechanisms involved in the putative effects. Mice subjected to warm hepatic I/R, and Kupffer cells (KCs) or RAW264.7 cells challenged with lipopolysaccharide (LPS)/H₂O₂, were pretreated with AA. Administration of AA significantly attenuated hepatic histopathological damage, global inflammatory level, apoptotic signaling level, as well as NLRP3 inflammasome activation. These effects were correlated with increased expression of peroxisome proliferator-activated receptor gamma (PPARγ). Conversely, pharmacological inhibition of PPARγ by GW9662 abolished the protective effects of AA on hepatic I/R injury and in turn aggravated NLRP3 inflammasome activation. Activation of NLRP3 inflammasome was most significant in nonparenchymal cells (NPCs). Depletion of KCs by gadolinium chloride (GdCl3) further attenuated the detrimental effects of GW9662 on hepatic I/R as well as NLRP3 activation. In vitro, AA concentration-dependently inhibited LPS/H₂O₂-induced NLRP3 inflammaosome activation in KCs and RAW264.7 cells. Either GW9662 or genetic knockdown of PPARγ abolished the AA-mediated inactivation of NLRP3 inflammasome. Mechanistically, AA attenuated I/R or LPS/H₂O₂-induced ROS production and phosphorylation level of JNK, p38 MAPK and IκBα but not ERK, a mechanism dependent on PPARγ. Finally, AA blocked the deleterious effects of LPS/H₂O₂-induced macrophage activation on hepatocyte viability in vitro, and improved survival in a lethal hepatic I/R injury model in vivo. Collectively, these data suggest that AA is effective in mitigating hepatic I/R injury through attenuation of KCs activation via PPARγ/NLRP3 inflammasome signaling pathway.

miR-494 up-regulates the PI3K/Akt pathway via targetting PTEN and attenuates hepatic ischemia/reperfusion injury in a rat model

A rat HIRI model was constructed and treated with an intraperitoneal injection of agomir-miR-494 or agomir-NC (negative control) for 7 days after the surgery. The pathophysiological changes in sham-operated rats, HIRI, HIRI + agomir-miR-494, and HIRI + agomir-NC were compared. The effect of miR-494 was also assessed in an H₂O₂-induced apoptosis model. Hepatic AML12 cells were transfected with mimics NC or miR-494 mimics, followed by 6-h H₂O₂ treatment. Cell proliferation and apoptosis were detected by CCK8 assay and flow cytometry, respectively. Further, the miR-494 target gene was identified by luciferase reporter assay, and verified both in vitro and in vivo experiments. The activity of AKT pathway was further analyzed in vivo by Western blot. HIRI + agomir-miR-494 rats exhibited significantly higher miR-494 expression, lower serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and glutamate dehydrogenase (GLDH) level, lower hepatic MDA, TOA, and OSI, alleviated hepatic necrosis, reduced hepatocyte apoptosis, and decreased expression of apoptosis-related proteins, when compared with HIRI + agomir-NC rats (P<0.05 or 0.01). After H₂O₂ treatment, AML-12 cells transfected with miR-494 mimics had significantly higher proliferation and lower apoptosis rate compared with mimics NC group (P<0.01). PTEN was identified as an miR-494 target gene. PTEN expression was significantly down-regulated in AML12 cells transfected with miR-494 mimics, and was up-regulated by treatment of miR-494 inhibitor (P<0.01). Moreover, HIRI + agomir-miR-494 rats exhibited significantly lower PTEN expression, and higher p-AKT, p-mTOR, and p-p70S6K levels compared with HIRI + agomir-NC rats. Therefore, miR-494 protected rats against hepatic ischemia/reperfusion (I/R) injury through down-regulating its downstream target gene PTEN, leading to the activation of PI3K/AKT signaling pathway.

Therapeutic activity of superoxide dismutase-containing enzymosomes on rat liver ischaemia-reperfusion injury followed by magnetic resonance microscopy

Liver ischaemia-reperfusion injury (IRI) may occur during hepatic surgery and is unavoidable in liver transplantation. Superoxide dismutase enzymosomes (SOD-enzymosomes), liposomes where SOD is at the liposomal surface expressing enzymatic activity in intact form without the need of liposomal disruption, were developed with the aim of having a better insight into its antioxidant therapeutic outcome in IRI. We also aimed at validating magnetic resonance microscopy (MRM) at 7T as a tool to follow IRI. SOD-enzymosomes were characterized and tested in a rat ischaemia-reperfusion model and the therapeutic outcome was compared with conventional long circulating SOD liposomes and free SOD using biochemical liver injury biomarkers, histology and MRM. MRM results correlated with those obtained using classical biochemical biomarkers of liver injury and liver histology. Moreover, MRM images suggested that the therapeutic efficacy of both SOD liposomal formulations used was related to prevention of peripheral biliary ductular damage and disrupted vascular architecture. Therefore, MRM at 7T is a useful technique to follow IRI. SOD-enzymosomes were more effective than conventional liposomes in reducing liver ischaemia-reperfusion injury and this may be due to a short therapeutic window.

Does a meso-caval shunt have positive effects in a pig large-for-size liver transplantation model?

In pediatric liver transplantations with LFS grafts, higher incidences of graft dysfunction probably occur due to IRI. It was postulated that increasing the blood supply to the graft by means of a meso-caval shunt could ameliorate the IRI. Eleven pigs underwent liver transplantation and were divided into two groups: LFS and LFS+SHUNT group. A series of flowmetric, metabolic, histologic, and molecular studies were performed. No significant metabolic differences were observed between the groups. One hour after reperfusion, portal flow was significantly lower in the recipients than in the donors, proving that the graft was maintained in low portal blood flow, although the shunt could promote a transient increase in the portal blood flow and a decrease in the arterial flow. Finally, it was verified that the shunt promoted a decrease in inflammation and steatosis scores and a decrease in the expression of the eNOS gene (responsible for the generation of nitric oxide in the vascular endothelium) and an increase in the expression of the proapoptotic gene BAX. The meso-caval shunt was responsible for some positive effects, although other deleterious flowmetric and molecular alterations also occurred.

Drag reducing polymers decrease hepatic injury and metastases after liver ischemia-reperfusion

Introduction

Surgery, a crucial therapeutic modality in the treatment of solid tumors, can induce sterile inflammatory processes which can result in metastatic progression. Liver ischemia and reperfusion (I/R) injury, an inevitable consequence of hepatic resection of metastases, has been shown to foster hepatic capture of circulating cancer cells and accelerate metastatic growth. Efforts to reduce these negative consequences have not been thoroughly investigated. Drag reducing polymers (DRPs) are blood-soluble macromolecules that can, in nanomolar concentrations, increase tissue perfusion, decrease vascular resistance and decrease near-wall microvascular concentration of neutrophils and platelets thereby possibly reducing the inflammatory microenvironment. We hypothesize that DRP can potentially be used to ameliorate metastatic capture of tumor cells and tumor growth within the I/R liver.

Methods

Experiments were performed utilizing a segmental ischemia model of mice livers. Five days prior or immediately prior to ischemia, murine colon adenocarcinoma cells (MC38) were injected into the spleen. DRP (polyethylene oxide) or a control of low-molecular-weight polyethylene glycol without drag reducing properties were administered intraperitoneally at the onset of reperfusion.

Results

After three weeks from I/R, we observed that liver I/R resulted in an increased ability to capture and foster growth of circulating tumor cells; in addition, the growth of pre-existing micrometastases was accelerated three weeks later. These effects were significantly curtailed when mice were treated with DRPs at the time of I/R. Mechanistic investigations in vivo indicated that DRPs protected the livers from I/R injury as evidenced by significant decreases in hepatocellular damage, neutrophil recruitment into the liver, formation of neutrophil extracellular traps, deposition of platelets, formation of microthrombi within the liver sinusoids and release of inflammatory cytokines.

Conclusions

DRPs significantly attenuated metastatic tumor development and growth. DRPs warrant further investigation as a potential treatment for liver I/R injury in the clinical setting to improve cancer-specific outcomes.

Topical Application of Mesenchymal Stromal Cells Ameliorated Liver Parenchyma Damage After Ischemia-Reperfusion Injury in an Animal Model

Supplemental digital content is available in the text.

Background

Ischemia-reperfusion injury (IRI) is commonly encountered after liver surgery. This study evaluated the hepatoprotective effects of topically applied adipose-derived mesenchymal stromal cells (ADMSCs) on hepatic IRI in a rat model.

Methods

ADMSCs from transgenic green fluorescent protein Sprague-Dawley rats were topically applied to the liver surface of Sprague-Dawley rats after hepatic IRI and fixed in position by fibrin glue (group A, n = 24). An equivalent amount of ADMSCs were administered through the portal (group B, n = 24) or tail vein (group C, n = 24). In the control group (group D, n = 20), no treatment was given to the IRI liver.

Results

All the rats in group A and group D survived. Within 2 days after hepatic IRI, only 50% of rats survived in group B, and ADMSCs were detected in thromboemboli within large vessels. 62.5% of the rats died in group C because most of the ADMSCs were trapped in the lungs. ADMSCs migrated across the liver capsule and homed to the injured liver parenchyma 3 days after topical application in group A. The homed ADMSCs expressed hepatocyte nuclear factor-4α and hepatocyte nuclear factor-1. Compared with group D, the rate of hepatic regeneration in group A was enhanced with less inflammation, smaller necrotic areas, and improved liver function. Proinflammatory cytokines IL-6, IL-21, and CD70 were significantly downregulated in group A by 6.3-, 2.7-, and 12.7-fold, respectively (P < 0.05). The neurogenic locus NOTCH homolog protein pathway was activated in the topical ADMSCs.

Conclusions

Topically applied adipose-derived mesenchymal stromal cells demonstrated hepatoprotective effects on hepatic IRI in an animal model.

The role of Kupffer cells in hepatic diseases

Kupffer cells (KCs) constitute 80-90% of the tissue macrophages present in the body. Essential to innate and adaptive immunity, KCs are responsible for the swift containment and clearance of exogenous particulates and immunoreactive materials which are perceived as foreign and harmful to the body. Similar to other macrophages, KCs also sense endogenous molecular signals that may result from perturbed homeostasis of the host. KCs have been implicated in host defense and the pathogenesis of various hepatic diseases, including endotoxin tolerance, liver transplantation, nonalcoholic fatty liver disease, and alcoholic liver disease. In this review, we summarized some novel findings associated with the role of KCs in hepatic diseases, such as the origin and mechanisms KCs polarization, molecular basis for caspase-1 activation called "non-canonical inflammasome pathway" involving the cleavage of Gsdmd by caspase-11, the important role of microRNA in liver transplantation, and so on. A better understanding of KCs biological characteristics and immunologic function in liver homeostasis and pathology may pave the way to investigate new diagnostic and therapeutic approaches for hepatic diseases.

Hepatocytes express the antimicrobial peptide HBD-2 after multiple trauma: an experimental study in human and mice

Background

Human-beta defensins (HBD) belong to the family of acute phase peptides and hold a broad antimicrobial spectrum that includes gram-positive and gram-negative bacteria. HBD are up-regulated after severe injuries but the source of posttraumatic HBD expression has not been focused on before.

In the current study we analysed the role of liver tissue in expression of HBD after multiple trauma in human and mice.

Methods

HBD-2 expression has been detected in plasma samples of 32 multiple trauma patients (ISS > 16) over 14 days after trauma by ELISA. To investigate major sources of HBD-2, its expression and regulation in plasma samples, polymorphonuclear neutrophils (PMN) and human tissue samples of liver and skin were analysed by ELISA. As liver samples of trauma patients are hard to obtain we tried to review findings in an established trauma model. Plasma samples and liver samples of 56 male C57BL/6 N-mice with a thorax trauma and a femur fracture were analysed by ELISA, real-time PCR and immunohistochemistry for murine beta defensin 4 (MBD-4) and compared with the expression of control group without trauma.

The induction of HBD-2 expression in cultured hepatocytes (Hep G2) was analysed after incubation with IL-6, supernatant of Staphylococcus aureus (SA) and Lipopolysaccharides (LPS). One possible signalling pathway was tested by blocking toll-like receptor 2 (TLR2) in hepatocytes.

Results

Compared to healthy control group, plasma of multiple traumatized patients and mice showed significantly higher defensin levels after trauma. Compared to skin cells, which are known for high beta defensin expression, liver tissue showed less HBD-2 expression, but higher HBD-2 expression compared to PMN. Immunhistochemical staining demonstrated upregulated MBD-4 in hepatocytes of traumatised mice. In HepG2 cells HBD-2 expression could be increased by stimulation with IL-6 and SA. Neutralization of HepG2 cells with αTLR2 showed reduced HBD-2 expression after stimulation with SA.

Conclusion

Plasma samples of multiple traumatized patients showed high expression of HBD-2, which may protect the severely injured patient from overwhelming bacterial infection. Our data support the hypothesis that liver is one possible source for HBD-2 in plasma while posttraumatic inflammatory response.

The Hepatoprotective and MicroRNAs Downregulatory Effects of Crocin Following Hepatic Ischemia-Reperfusion Injury in Rats

Background. Liver ischemia-reperfusion (IR) injury is one of the chief etiologies of tissue damage during liver transplantation, hypovolemic shock, and so forth. This study aimed to evaluate hepatoprotective effect of crocin on IR injury and on microRNAs (miR-122 and miR-34a) expression. Materials and Methods. 32 rats were randomly divided into four groups: sham, IR, crocin pretreatment (Cr), and crocin pretreatment + IR (Cr + IR) groups. In sham and Cr groups, animals were given normal saline (N/S) and Cr (200 mg/Kg) for 7 consecutive days, respectively, and laparotomy without inducing IR was done. In IR and Cr + IR groups, N/S and Cr were given for 7 consecutive days and rats underwent a partial (70%) ischemia for 45 min/reperfusion for 60 min. Blood and tissue samples were taken for biochemical, molecular, and histopathological examinations. Results. The results showed decreased levels of antioxidants activity and increased levels of liver enzymes improved by crocin. The expression of miR-122, miR-34a, and p53 decreased, while Nrf2 increased by crocin. Crocin ameliorated histopathological changes. Conclusion. The results demonstrated that crocin protected the liver against IR injury through increasing the activity of antioxidant enzymes, improving serum levels of liver enzymes, downregulating miR-122, miR-34a, and p53, and upregulating Nrf2 expression.

Preconditioning methods in the management of hepatic ischemia reperfusion- induced injury: Update on molecular and future perspectives

Hepatic IR (ischemia reperfusion) injury is a commonly encountered obstacle in the post-operative management of hepatic surgery. Hepatic IR occurs during 'Pringle maneuver' for reduction of blood loss or during a brief period of cold storage followed by reperfusion of liver grafts. The stress induced during hepatic IR, triggers a spectrum of cellular responses leading to the varying degrees of hepatic complications which in turn affect the post operative care. Different preconditioning methods either activate or subdue different sets of molecular signals, resulting in varied levels of protection against hepatic IR injury. Yet, there is a serious lacuna in the knowledge regarding the choice of preconditioning methods and the resulting molecular changes in order to assess the efficiency and choice of these methods correctly. This review provides an update on the various preconditioning approaches such as surgical/ischemic, antioxidant, pharmaceutical and genetic preconditioning strategies published during last six years (2009-2015). Further, we discuss the attenuation or inhibition of specific inflammatory, apoptotic and necrotic markers in the various experimental models of liver IR subjected to different preconditioning strategies. While enlisting the controversies in the ischemic preconditioning strategy, we bring out the uncertainties in the existing molecular targets and their reliability in the attenuation of hepatic IR injury. Future research studies would include the novel preconditioning strategies employ i) the targeted gene silencing of key molecular targets inducing IR, ii) hyper expression of beneficial molecular signals against IR via gene transfer techniques. The above studies would see the combination of these latest techniques with the established preconditioning strategies for better post-operative hepatic management.

Enolate-Forming Compounds as a Novel Approach to Cytoprotection

Evidence from laboratory studies and clinical trials suggests that plant-derived polyphenolic compounds such as curcumin, resveratrol, or phloretin might be useful in the treatment of certain diseases (e.g., Alzheimer's disease) and acute tissue injury states (e.g., spinal cord trauma). However, despite this potential, the corresponding chemical instability, toxic potential, and low bioavailability of these compounds could limit their ultimate clinical relevance. We have shown that pharmacophores of curcumin (e.g., 2-acetylcyclopentanone) and phloretin (e.g., 2',4',6'-trihydroxyacetophenone; THA) can provide cytoprotection in cell culture and animal models of oxidative stress injury. These pharmacophores are 1,3-dicarbonyl and polyphenol derivatives, the enol groups of which can ionize in biological solutions to form an enolate. This carbanionic moiety can chelate metal ions and, as a nucleophile, can scavenge toxic electrophiles (e.g., acrolein, 4-hydroxy-2-nonenal, and N-acetyl-p-benzoquinone imine) involved in many pathogenic conditions. Aromatic derivatives such as THA can also trap free oxygen and nitrogen radicals and thereby provide another layer of cytoprotection. The multifunctional character of these enolate-forming compounds suggests an ability to block pathogenic processes (e.g., oxidative stress) at several steps. The purpose of this review is to discuss research supporting our theory that enolate formation is a significant cytoprotective property that represents a platform for development of pharmacotherapeutic approaches to a variety of toxic and pathogenic conditions. Our discussion will focus on mechanism and structure-activity studies that define enolate chemistry and their corresponding relationships to cytoprotection.

Blocking Notch signal in myeloid cells alleviates hepatic ischemia reperfusion injury by repressing the activation of NF-κB through CYLD

Ischemia-reperfusion (I/R) is a major reason of hepatocyte injury during liver surgery and transplantation. Myeloid cells including macrophages and neutrophils play important roles in sustained tissue inflammation and damage, but the mechanisms regulating myeloid cells activity have been elusive. In this study, we investigate the role of Notch signaling in myeloid cells during hepatic I/R injury by using a mouse model of myeloid specific conditional knockout of RBP-J. Myeloid-specific RBP-J deletion alleviated hepatic I/R injury. RBP-J deletion in myeloid cells decreased hepatocytes apoptosis after hepatic I/R injury. Furthermore, myeloid-specific RBP-J deletion led to attenuated inflammation response in liver after I/R injury. Consistently, Notch blockade reduced the production of inflammatory cytokines by macrophages in vitro. We also found that blocking Notch signaling reduced NF-κB activation and increased cylindromatosis (CYLD) expression and knockdown of CYLD rescued reduction of inflammatory cytokines induced by Notch blockade in macrophages during I/R injury in vitro. On the other hand, activation of Notch signaling in macrophages led to increased inflammatory cytokine production and NF-κB activation and decreased CYLD expression in vitro. These data suggest that activation of Notch signaling in myeloid cells aggravates I/R injury, by enhancing the inflammation response by NF-κB through down regulation of CYLD.

Protection of rat liver against hepatic ischemia-reperfusion injury by a novel selenocysteine-containing 7-mer peptide

Hepatic ischemia-reperfusion (I-R) injury causes acute organ damage or dysfunction, and remains a problem for liver transplantation. In the I-R phase, the generation of reactive oxygen species aggravates the injury. In the current study, a novel selenocysteine-containing 7‑mer peptide (H-Arg-Sec-Gly-Arg-Asn-Ala-Gln-OH) was constructed to imitate the active site of an antioxidant enzyme, glutathione peroxidase (GPX). The 7‑mer peptide which has a lower molecular weight, and improved water‑solubility, higher stability and improved cell membrane permeability compared with other GPX mimics. Its GPX activity reached 13 U/µmol, which was 13 times that of ebselen (a representative GPX mimic). The effect of this GPX mimic on I‑R injury of the liver was assessed in rats. The 7‑mer peptide significantly inhibited the increase in serum hepatic amino‑transferases, tissue malondialdehyde, nitric oxide contents, myeloperoxidase activity and decrease of GPX activity compared with I‑R tissue. Following treatment with the 7‑mer peptide, the expression of B‑cell CLL/lymphoma‑2 (Bcl‑2) was significantly upregulated at the mRNA and protein level compared with the I‑R group, as determined by reverse transcription‑polymerase chain reaction and immunohistochemistry, respectively. By contrast, Bcl‑2 associated X protein (Bax) was downregulated by the 7‑mer peptide compared the I‑R group. Histological and ultrastructural changes of the rat liver tissue were also compared among the experimental groups. The results of the current study suggest that the 7‑mer peptide protected the liver against hepatic I‑R injury via suppression of oxygen‑derived free radicals and regulation of Bcl‑2 and Bax expression, which are involved in the apoptosis of liver cells. The findings of the present study will further the investigation of the 7-mer peptide as an effective therapeutic agent in hepatic I-R injury.

The effects of tadalafil and pentoxifylline on apoptosis and nitric oxide synthase in liver ischemia/reperfusion injury

The aim of this study was to investigate the effects of tadalafil (TDF) and pentoxifylline (PTX) on hepatic apoptosis and the expressions of endothelial and inducible nitric oxide synthases (eNOS and iNOS) after liver ischemia/reperfusion (IR). Forty Wistar albino rats were randomly divided into five groups (n=8) as follows: sham group; IR group with ischemia/reperfusion alone; low-dose and high-dose TDF groups received 2.5 mg/kg and 10 mg/kg TDF, respectively; and PTX group received 40 mg/kg PTX. Blood was collected for the analysis of serum alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transferase, uric acid, malondialdehyde (MDA), and total antioxidant capacity (TAC). MDA and TAC also were measured in liver tissue. Histopathological examination was performed to assess the severity of hepatic injury. Apoptosis was evaluated using the apoptosis protease-activating factor 1 (APAF-1) antibody; the expressions of eNOS and iNOS were also assessed by immunohistochemistry in all groups. Serum alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transferase, uric acid, MDA, and TAC, tissue MDA and TAC levels, hepatic injury, and score for extent and for intensity of eNOS, iNOS, and apoptosis protease-activating factor 1 were significantly different in TDF and PTX groups compared to the IR group. High dose-TDF and PTX have the best protective effect on IR-induced liver tissue damage. This study showed that TDF and PTX supplementation may be helpful in preventing free oxygen radical damage, lipid peroxidation, hepatocyte necrosis, and apoptosis in liver IR injury and minimizing liver damage.

Hepatic ischemia reperfusion injury: A systematic review of literature and the role of current drugs and biomarkers

Hepatic ischemia reperfusion injury (IRI) is not only a pathophysiological process involving the liver, but also a complex systemic process affecting multiple tissues and organs. Hepatic IRI can seriously impair liver function, even producing irreversible damage, which causes a cascade of multiple organ dysfunction. Many factors, including anaerobic metabolism, mitochondrial damage, oxidative stress and secretion of ROS, intracellular Ca(2+) overload, cytokines and chemokines produced by KCs and neutrophils, and NO, are involved in the regulation of hepatic IRI processes. Matrix Metalloproteinases (MMPs) can be an important mediator of early leukocyte recruitment and target in acute and chronic liver injury associated to ischemia. MMPs and neutrophil gelatinase-associated lipocalin (NGAL) could be used as markers of I-R injury severity stages. This review explores the relationship between factors and inflammatory pathways that characterize hepatic IRI, MMPs and current pharmacological approaches to this disease.

Interleukin-6 and rs1800796 locus single nucleotide polymorphisms in response to hypoxia/reoxygenation in hepatocytes

Ischemia-reperfusion injury due to hypoxia/reoxygenation (H/R) is one of the main causes of liver damage during liver surgery. Donor interleukin-6 (IL-6) rs1800796 single nucleotide polymorphisms (SNPs) affect the metabolism of tacrolimus following liver transplantation-related hepatic H/R. This study investigated the response of IL-6 and its promoter polymorphisms to hepatic H/R in liver parenchymal cells. The association between IL-6 rs1800796 SNPs and IL‑6 expression was measured in 84 disease-free liver tissues using tissue microarrays and immunohistochemistry. Subsequently, LO2G, LO2C and NC-LO2 cells were successfully constructed via stable lentivirus-mediated transfection. The effects of IL-6 and its SNPs on the biological function of LO2 cells were examined using a cell model of H/R. Our results revealed that IL-6 was mainly expressed in hepatocytes. The intermediate IL-6 expression rate in genotype CC carriers was higher than that in genotype CG/GG carriers (P=0.006), which was subsequently verified at the IL-6 mRNA level (P=0.002). The concentrations of alanine aminotransferase in the LO2G cells were significantly higher than those in the LO2C cells following H/R for 6 h and H/R for 24 h (P<0.05). The viability of the LO2C cells was higher than that of the LO2G cells (P<0.05). Furthermore, the expression of IL-6 and its downstream molecules was significantly increased in the LO2C cells compared with the LO2G cells (P<0.05). Therefore, the sequence variants of rs1800796 SNPs (G→C) exhibit an increased IL-6 transcription efficiency in liver parenchymal cells. In addition, the increased expression of IL-6 protects the hepatocytes following hepatic H/R injury.

The novel TLR9 antagonist COV08-0064 protects from ischemia/reperfusion injury in non-steatotic and steatotic mice livers

Ischemia/reperfusion (I/R) injury constitutes a major reason for failure of liver surgeries and transplantation. I/R injury is more severe in steatotic livers and limits their use in transplantation. Here, we present a novel and selective Toll-like receptor 9 (TLR9) antagonist COV08-0064 and test its potential to protect from I/R-induced injury in normal and steatotic livers. The in vivo effects of COV08-0064 pretreatment were investigated on normal chow diet (NCD) and high fat diet (HFD)-fed mice subjected to segmental (70%) warm hepatic I/R. Also, the in vitro effects of COV08-0064 were elucidated in murine macrophages and dendritic cells. Mice on a HFD had pronouncedly greater hepatic I/R injury than mice on a NCD. COV08-0064-pretreatment to both NCD and HFD-fed mice reduced hepatic I/R injury. COV08-0064-pretreatment was associated with less production of the liver inflammatory cytokines and mediators TNF-α, IL-1β, IL-6, NLRP3, iNOS and MCP-1. These manifestations were preceded with inhibition of JNK and ERK phosphorylation and TLR9 cleavage in the liver. COV08-0064 enhanced the hepatic expression of the endogenous anti-inflammatory cytokines IL-10 and IL-1Ra at the early phase I/R injury. In vitro, COV08-0064 selectively blocked mRNA upregulation of TNF-α, IL-1β, NLRP3 and MCP-1 in macrophages and IFN-β mRNA in dendritic cells induced by the TLR9 agonist CpG-ODN. These effects were concordant with inhibition of JNK, ERK, IκBα and IKKα/β phosphorylation. In conclusion, TLR9 signaling inhibition by COV08-0064 may be an effective approach in liver surgeries including transplantation to limit I/R-injury and overcome the shortages in the donor pool by incorporating steatotic livers.

Global MicroRNA Expression Profiling of Mouse Livers following Ischemia-Reperfusion Injury at Different Stages

Hepatic ischemia-reperfusion injury is a dynamic process consisting of two stages: ischemia and reperfusion, and triggers a cascade of physiological and biochemical events. Given the important role of microRNAs in regulating gene expression, we analyzed gene expression changes in mouse livers at sham control, ischemia stage, and reperfusion stage. We generated global expression profiles of microRNA and mRNA genes in mouse livers subjected to ischemia-reperfusion injury at the three stages, respectively. Comparison analysis showed that reperfusion injury had a distinct expression profile whereas the ischemia sample and the sham control were clustered together. Consistently, there are 69 differentially expressed microRNAs between the reperfusion sample and the sham control whereas 28 differentially expressed microRNAs between the ischemia sample and the sham control. We further identified two modes of microRNA expression changes in ischemia-reperfusion injury. Functional analysis of both the differentially expressed microRNAs in the two modes and their target mRNAs revealed that ischemia injury impaired mitochondrial function, nutrient consumption, and metabolism process. In contrast, reperfusion injury led to severe tissue inflammation that is predominantly an innate-immune response in the ischemia-reperfusion process. Our staged analysis of gene expression profiles provides new insights into regulatory mechanisms of microRNAs in mouse hepatic IR injury.

Serial volumetric assessment of large for size liver grafts after whole cadaveric liver transplant in adults: do large liver grafts shrink in size?

BACKGROUND

After whole graft orthotopic liver transplantation (OLT), adaptation of the large grafts' volume to recipient weight is widely accepted despite the paucity of evidence on this subject.

METHODS

Thirty nine patients with GRWR > 2.5% were included in this study and subsequently divided into two groups with 3 ≥ GRWR > 3%. Patients had CT scans at three predetermined time points after OLT used for measuring the liver volume. The objective of this study is to evaluate the volumetric changes of whole large liver grafts after adult OLT.

RESULTS

At LT, the mean graft recipient body weight ratio (GRWR) was 3.1 ± 0.4%. The mean liver weight was 1881 ± 68 g at LT, 2014 ± 99 ml at one week, 1725 ± 126 ml at 3 months, and 1632 ± 117 (ml) at >6 months. There is an initial increase at 1 week after LT and a subsequent decrease of liver volume on later measurements. None of the late volume measurements were significantly different from the initial graft volume at liver transplant in pair wise comparisons ANOVA repeated measures (p > 0.05). Similarly, the mean GRWR did not change significantly between the initial calculation at transplantation date and the subsequent measurements during the different study time points (F = 0.04, p = 0.96) with a mean of 3.1% (95% CI = 2.2-4.2). AUC ROC discriminated a cutoff of 3% for the initial GRWR above which grafts tend to decrease in size over time (c statistics = 0.74, p = 0.036). In a Clustered ANOVA repeated measures, there was no significant difference in the changes of liver volume between both groups. However, patients with GRWR > 3 showed a trend towards a latent reduction in volume over the tracing period. There was a tendency, but none significant; towards a higher bilirubin, AST, ALT levels over the first postoperative days in recipients with GRWR > 3.

CONCLUSION

Large grafts do not significantly decrease in size. Nonetheless, grafts weighing >3% of the GRWR show a different trend towards decrease in size over time.

Regulation of drug-metabolizing enzymes by local and systemic liver injuries

INTRODUCTION

Drug metabolism and disposition are critical in maintaining the chemical and functional homeostasis of xenobiotics/drugs and endobiotics. The liver plays an essential role in drug metabolism and disposition due to its abundant expression of drug-metabolizing enzymes (DMEs) and transporters. There is growing evidence to suggest that many hepatic and systemic diseases can affect drug metabolism and disposition by regulating the expression and/or activity of DMEs and transporters in the liver.

AREAS COVERED

This review focuses on the recent progress on the regulation of DMEs by local and systemic liver injuries. Liver ischemia and reperfusion (I/R) and sepsis are used as examples of local and systemic injury, respectively. The reciprocal effect of the expression and activity of DMEs on animals' sensitivity to local and systemic liver injuries is also discussed.

EXPERT OPINION

Local and systemic liver injuries have a major effect on the expression and activity of DMEs in the liver. Understanding the disease effect on DMEs is clinically important due to the concern of disease-drug interactions. Future studies are necessary to understand the mechanism by which liver injury regulates DMEs. Human studies are also urgently needed in order to determine whether the results in animals can be replicated in human patients.

Circulating Fibroblast Growth Factor 21 Is A Sensitive Biomarker for Severe Ischemia/reperfusion Injury in Patients with Liver Transplantation

Hepatic ischemia/reperfusion (I/R) injury is a major cause of morbidity and mortality after liver surgery. Therefore, it is important to identity reliable biomarkers to assist early diagnosis of hepatic I/R injury. This study aimed to investigate the potential of serum levels of fibroblast growth factor 21 (FGF21) as a biomarker for hepatic I/R injury in patients with liver transplantation. Two independent cohorts of liver transplantation patients were recruited for determination of serum levels of FGF21, ALT, and AST. The results demonstrated that serum FGF21 at 2 hours post-reperfusion in cohort-1 exhibited an approximately 20-fold elevation relative to those in healthy subjects. In blood samples dynamically collected in cohort-2, a dramatic increase in serum FGF21 levels (~25-fold) was observed at two hours after surgery, whereas the peak levels of serum ALT and AST were detected only after 24 hours. Temporal correlation analysis demonstrated a significant association of peak serum levels of FGF21 at 2 hours with the magnitude of the increase in both serum ALT and AST levels at 24 hours post transplantation. In conclusion, serum FGF21 may represent a sensitive and specific prognostic biomarker for early detection of I/R injury in patients with liver transplantation.

Clinical outcomes and genetic expression profile in human liver graft dysfunction during ischemia/reperfusion injury

INTRODUCTION

This study aims to compare the molecular gene expression during ischemia reperfusion injury. Several surgical times were considered: in the beginning of the harvesting (T0), at the end of the cold ischemia period (T1), and after reperfusion (T2) and compared with graft dysfunction after liver transplant (OLT).

METHODS

We studied 54 patients undergoing OLT. Clinical, laboratory data, and histologic data (Suzuki classification) as well as the Survival Outcomes Following Liver Transplantation (SOFT) score were used and compared with the molecular gene expression of the following genes: Interleukin (IL)-1b, IL-6, tumor necrosis factor-α, perforin, E-selectin (SELE), Fas-ligand, granzyme B, heme oxygenase-1, and nitric oxide synthetase.

RESULTS

Fifteen patients presented with graft dysfunction according to SOFT criteria. No relevant data were obtained by comparing the variables graft dysfunction and histologic variables. We observed a statistically significant relation between SELE at T0 (P = .013) and IL-1β at T0 (P = .028) and early graft dysfunction.

CONCLUSIONS

We conclude that several genetically determined proinflammatory expressions may play a critical role in the development of graft dysfunction after OLT.

Postoperative peak serum C-reactive protein is a predictor of outcome following liver transplantation for hepatocellular carcinoma

CONTEXT

C-reactive protein (CRP), a biomarker of inflammation, may correlate with prognosis in several malignancies.

OBJECTIVE

To investigate the prognostic impact of early postoperative peak serum levels of CRP on tumor-specific outcome in 106 liver transplant patients with hepatocellular carcinoma (HCC).

METHODS AND RESULTS

In multivariate Cox regression analysis, a posttransplant elevated peak CRP level (>versus ≤ 3.5 mg/dl) was identified as an independent predictor of poor recurrence-free survival (p = 0.01; HR = 4.04; CI = 1.399-11.640).

CONCLUSION

Early postoperative serum CRP may serve as a useful inflammation-based biomarker of outcome in liver transplant patients with HCC.

Mitochondrial Dysfunction and Autophagy in Hepatic Ischemia/Reperfusion Injury

Ischemia/reperfusion (I/R) injury remains a major complication of liver resection, transplantation, and hemorrhagic shock. Although the mechanisms that contribute to hepatic I/R are complex and diverse involving the interaction of cell injury in hepatocytes, immune cells, and endothelium, mitochondrial dysfunction is a cardinal event culminating in hepatic reperfusion injury. Mitochondrial autophagy, so-called mitophagy, is a key cellular process that regulates mitochondrial homeostasis and eliminates damaged mitochondria in a timely manner. Growing evidence accumulates that I/R injury is attributed to defective mitophagy. This review aims to summarize the current understanding of autophagy and its role in hepatic I/R injury and highlight the various therapeutic approaches that have been studied to ameliorate injury.

Treating ischaemia-reperfusion injury with prostaglandin E1 reduces the risk of early hepatocellular carcinoma recurrence following liver transplantation

BACKGROUND

Surgical stress by hepatic ischaemia-reperfusion (I/R) is supposed to promote intra- and extrahepatic tumour recurrence. Treatment with prostaglandin E1 (PGE1) has been shown to attenuate hepatic I/R injury in liver transplant patients, but the potential anti-cancer effects have not been analysed.

AIM

To evaluate the impact of PGE1 therapy on risk of hepatocellular carcinoma (HCC) recurrence in liver transplant patients.

METHODS

A retrospective review of 106 liver transplant patients with HCC was conducted. Fifty-nine patients underwent early post-liver transplantation (LT) treatment with the stable PGE1 analogue alprostadil. Administration of alprostadil was correlated with outcome in uni- and multivariate analysis. Subgroup analysis focused on patients with HCC beyond the Milan criteria (Milan Out) on radiographic imaging.

RESULTS

Three- and 5-year recurrence-free survival rates were 87.9% and 85.7% in the PGE1-group, but only 65.3% and 63.1% in the non-PGE1-population (P = 0.003). Multivariate Cox regression analysis identified absence of PGE1-treatment (HR = 11.42), along with presence of poor tumour grading (HR = 2.69) and microvascular tumour invasion (HR = 35.8) to be independently associated with early (within 12 months) HCC recurrence. In Milan Out-patients, only therapy with PGE1 (HR = 5.09) and well/moderate tumour differentiation (HR = 6.51) were independent promoters of recurrence-free survival.

CONCLUSIONS

Treating hepatic ischaemia-reperfusion injury with alprostadil reduces the risk of early HCC recurrence following LT. In particular patients with HCC exceeding the Milan criteria seem to benefit from PGE1-treatment. The molecular mechanisms of the anti-tumour effects need to be further assessed.

Mitochondrial Damage-Associated Molecular Patterns (MTDs) Are Released during Hepatic Ischemia Reperfusion and Induce Inflammatory Responses

Ischemia / reperfusion injury (IRI) during the course of liver transplantation enhances the immunogenicity of allografts and thus impacts overall graft outcome. This sterile inflammatory insult is known to activate innate immunity and propagate organ damage through the recognition of damage-associate molecular pattern (DAMP) molecules. The purpose of the present study was to investigate the role of mitochondrial DAMPs (MTDs) in the pathogenesis of hepatic IRI. Using in vitro models we observed that levels of MTDs were significantly higher in both transplantation-associated and warm IR, and that co-culture of MTDs with human and rat hepatocytes significantly increased cell death. MTDs were also released in an in vivo rat model of hepatic IRI and associated with increased secretion of inflammatory cytokines (TNF-α, IL-6, and IL-10) and increased liver injury compared to the sham group. Our results suggest that hepatic IR results in a significant increase of MTDs both in vitro and in vivo suggesting that MTDs may serve as a novel marker in hepatic IRI. Co-culture of MTDs with hepatocytes showed a decrease in cell viability in a concentration dependent manner, which indicates that MTDs is a toxic mediator participating in the pathogenesis of liver IR injury.

Preserving low perfusion during surgical liver blood inflow control prevents hepatic microcirculatory dysfunction and irreversible hepatocyte injury in rats

Hepatic ischaemia/reperfusion (I/R) injury is of primary concern during liver surgery. We propose a new approach for preserving low liver blood perfusion during hepatectomy either by occlusion of the portal vein (OPV) while preserving hepatic artery flow or occlusion of the hepatic artery while limiting portal vein (LPV) flow to reduce I/R injury. The effects of this approach on liver I/R injury were investigated. Rats were randomly assigned into 4 groups: sham operation, occlusion of the portal triad (OPT), OPV and LPV. The 7-day survival rate was significantly improved in the OPV and LPV groups compared with the OPT group. Microcirculatory liver blood flow recovered rapidly after reperfusion in the OPV and LPV groups but decreased further in the OPT group. The OPV and LPV groups also showed much lower ALT and AST levels, Suzuki scores, inflammatory gene expression levels, and parenchymal necrosis compared with the OPT group. An imbalance between the expression of vasoconstriction and vasodilation genes was observed in the OPT group but not in the OPV or LPV group. Therefore, preserving low liver blood perfusion by either the OPV or LPV methods during liver surgery is very effective for preventing hepatic microcirculatory dysfunction and hepatocyte injury.

Anti-CD163-dexamethasone protects against apoptosis after ischemia/reperfusion injuries in the rat liver

Aim

The Pringle maneuver is a way to reduce blood loss during liver surgery. However, this may result in ischemia/reperfusion injury in the development of which Kupffer cells play a central role. Corticosteroids are known to have anti-inflammatory effects. Our aim was to investigate whether a conjugate of dexamethasone and antibody against the CD163 macrophage cell surface receptor could reduce ischemia/reperfusion injury in the rat liver.

Methods

Thirty-six male Wistar rats were used for the experiments. Animals were randomly divided into four groups of eight receiving anti-CD163-dexamethasone, high dose dexamethasone, low dose dexamethasone or placebo intravenously 18 h before laparotomy with subsequent 60 min of liver ischemia. After reperfusion for 24 h the animals had their liver removed. Bloods were drawn 30 min and 24 h post ischemia induction. Liver cell apoptosis and necrosis were analyzed by stereological quantification.

Results

After 24 h' reperfusion, the fraction of cell in non-necrotic tissues exhibiting apoptotic profiles was significantly lower in the high dose dexamethasone (p = 0.03) and anti-CD163-dex (p = 0.03) groups compared with the low dose dexamethasone and placebo groups. There was no difference in necrotic cell volume between groups. After 30 min of reperfusion, levels of haptoglobin were significantly higher in the anti-CD163-dex and high dose dexamethasone groups. Alanine aminotransferase and alkaline phosphatase were significantly higher in the high dose dexamethasone group compared to controls after 24 h' reperfusion.

Conclusions

We show that pharmacological preconditioning with anti-CD163-dex and high dose dexamethasone reduces the number of apoptotic cells following ischemia/reperfusion injury.

•

We investigated the effect of pharmacologic preconditioning with HDD, LDD and anti-CD163-dex on ischemia/reperfusion injury.

•

Liver cell apoptosis and necrosis were analyzed by stereological quantification.

•

Anti-CD163-dex and high dose dexamethasone reduces the number of apoptotic cells following ischemia/reperfusion injury.

Extended Ischemia Times Promote Risk of HCC Recurrence in Liver Transplant Patients

BACKGROUND

There is increasing evidence that ischemia-reperfusion injury (IRI) promotes vasculogenesis and tumor outgrowth in the liver. Hepatic IRI is exaggerated by prolongation of ischemia times.

AIMS

The aim of this retrospective analysis was to assess the impact of ischemia times on risk of hepatocellular carcinoma (HCC) recurrence after liver transplantation (LT). Subgroup analysis focused on patients with (18)F-fluoro-deoxy-glucose ((18)F-FDG)-avid HCC on pretransplant positron emission tomography (PET).

METHODS

A total of 103 liver transplant patients with HCC were included in this study. The impact of cold (CIT), warm (WIT), and total ischemia times (TIT) along with other prognostic variables on posttransplant outcome was analyzed in uni- and multivariate analysis.

RESULTS

Twenty-four patients (23.3 %) developed tumor relapse after LT. Mean durations of CIT (468.0 vs. 375.5 min; P = 0.001), WIT (58.4 vs. 45.7 min; P = 0.001), and TIT (525.8 vs. 422.0 min; P < 0.001) were significantly longer in patients with compared to those without HCC recurrence. In multivariate regression analysis, (18)F-FDG-avid HCC (odds ratio [OR] 73.4), WIT >50 min (OR 52.5), alpha-fetoprotein level >400 IU/ml (OR 11.1), and Milan Out status (OR 7.4) were identified as independent predictors of HCC recurrence. In the subgroup of patients with PET-positive HCC, WIT remained the only independent variable to predict HCC recurrence (OR 15.5).

CONCLUSION

Prolongation of ischemia times promotes the risk of HCC recurrence after LT, especially in patients with unfavorable tumor biology on PET imaging.

Blocking cold-inducible RNA-binding protein protects liver from ischemia-reperfusion injury

Cold-inducible RNA-binding protein (CIRP) is a nuclear protein that has been recently identified as a novel inflammatory mediator in hemorrhagic shock and sepsis. We hypothesized that CIRP acts as a potent inflammatory mediator in hepatic ischemia-reperfusion (I/R), and thus blocking CIRP protects against I/R-induced liver injury. Male C57BL/6 mice were subjected to 70% hepatic ischemia by microvascular clamping of the hilum of the left and median liver lobes for 60 min, followed by reperfusion. Anti-CIRP antibody (1 mg/kg body weight) or vehicle (normal saline) in 0.2 mL was injected via the internal jugular vein at the beginning of the reperfusion. Blood and liver tissues were collected 24 h after I/R for various measurements, and a 10-day survival study was performed. Cold-inducible RNA-binding protein released into the circulation was significantly increased 24 h after hepatic I/R. Anti-CIRP antibody treatment markedly reduced hepatocellular damage markers and significantly improved the liver microarchitecture. Anti-CIRP also reduced the systemic and local inflammation demonstrated by attenuation in both serum and hepatic levels of interleukin 6. The expression of neutrophil-attracting chemokine as well as liver neutrophil infiltration was reduced by anti-CIRP treatment. Anti-CIRP also dramatically decreased the amount of apoptosis and nitrosative stress, evidenced by decrease in TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) staining and inducible nitric oxide synthase and cyclooxygenase 2 levels, respectively. Finally, the 10-day survival rate was increased from 37.5% in the vehicle group to 75% in the anti-CIRP treatment group. Thus, targeting CIRP offers potential therapeutic implications in the treatment of hepatic I/R injury.

Damage-associated molecular pattern-activated neutrophil extracellular trap exacerbates sterile inflammatory liver injury

Innate immunity plays a crucial role in the response to sterile inflammation such as liver ischemia/reperfusion (I/R) injury. The initiation of liver I/R injury results in the release of damage-associated molecular patterns, which trigger an innate immune and inflammatory cascade through pattern recognition receptors. Neutrophils are recruited to the liver after I/R and contribute to organ damage and innate immune and inflammatory responses. Formation of neutrophil extracellular traps (NETs) has been recently found in response to various stimuli. However, the role of NETs during liver I/R injury remains unknown. We show that NETs form in the sinusoids of ischemic liver lobes in vivo. This was associated with increased NET markers, serum level of myeloperoxidase-DNA complexes, and tissue level of citrullinated-histone H3 compared to control mice. Treatment with peptidyl-arginine-deiminase 4 inhibitor or DNase I significantly protected hepatocytes and reduced inflammation after liver I/R as evidenced by inhibition of NET formation, indicating the pathophysiological role of NETs in liver I/R injury. In vitro, NETs increase hepatocyte death and induce Kupffer cells to release proinflammatory cytokines. Damage-associated molecular patterns, such as High Mobility Group Box 1 and histones, released by injured hepatocytes stimulate NET formation through Toll-like receptor (TLR4)- and TLR9-MyD88 signaling pathways. After neutrophil depletion in mice, the adoptive transfer of TLR4 knockout or TLR9 knockout neutrophils confers significant protection from liver I/R injury with a significant decrease in NET formation. In addition, we found inhibition of NET formation by the peptidyl-arginine-deiminase 4 inhibitor and that DNase I reduces High Mobility Group Box 1 and histone-mediated liver I/R injury.

CONCLUSION

Damage-associated molecular patterns released during liver I/R promote NET formation through the TLR signaling pathway. Development of NETs subsequently exacerbates organ damage and initiates inflammatory responses during liver I/R.

Cilostazol attenuates murine hepatic ischemia and reperfusion injury via heme oxygenase-dependent activation of mitochondrial biogenesis

Hepatic ischemia-reperfusion (I/R) can cause hepatocellular injury associated with the inflammatory response and mitochondrial dysfunction. We studied the protective effects of the phosphodiesterase inhibitor cilostazol in hepatic I/R and the roles of mitochondria and the Nrf2/heme oxygenase-1 (HO-1) system. Wild-type, Hmox1(-/-), or Nrf2(-/-) mice were subjected to hepatic I/R in the absence or presence of cilostazol followed by measurements of liver injury. Primary hepatocytes were subjected to cilostazol with the HO-1 inhibitor ZnPP, or Nrf2-specific siRNA, followed by assessment of mitochondrial biogenesis. Preconditioning with cilostazol prior to hepatic I/R protected against hepatocellular injury and mitochondrial dysfunction. Cilostazol reduced the serum levels of alanine aminotransferase, TNF-α, and liver myeloperoxidase content relative to control I/R-treated mice. In primary hepatocytes, cilostazol increased the expression of HO-1, and markers of mitochondrial biogenesis, PGC-1α, NRF-1, and TFAM, induced the mitochondrial proteins COX III and COX IV and increased mtDNA and mitochondria content. Pretreatment of primary hepatocytes with ZnPP inhibited cilostazol-induced PGC-1α, NRF-1, and TFAM mRNA expression and reduced mtDNA and mitochondria content. Genetic silencing of Nrf2 prevented the induction of HO-1 and mitochondrial biogenesis by cilostazol in HepG2 cells. Cilostazol induced hepatic HO-1 production and mitochondrial biogenesis in wild-type mice, but not in Hmox1(-/-) or Nrf2(-/-) mice, and failed to protect against liver injury in Nrf2(-/-) mice. These results suggest that I/R injury can impair hepatic mitochondrial function, which can be reversed by cilostazol treatment. These results also suggest that cilostazol-induced mitochondrial biogenesis was mediated by an Nrf-2- and HO-1-dependent pathway.

Genomic profiles and predictors of early allograft dysfunction after human liver transplantation

Early hepatic allograft dysfunction (EAD) manifests posttransplantation with high serum transaminases, persistent cholestasis, and coagulopathy. The biological mechanisms are poorly understood. This study investigates the molecular mechanisms involved in EAD and defines a gene expression signature revealing different biological pathways in subjects with EAD from those without EAD, a potential first step in developing a molecular classifier as a potential clinical diagnostic. Global gene expression profiles of 30 liver transplant recipients of deceased donor grafts with EAD and 26 recipients without graft dysfunction were investigated using microarrays of liver biopsies performed at the end of cold storage and after graft reperfusion prior to closure. Results reveal a shift in inflammatory and metabolic responses between the two time points and differences between EAD and non-EAD. We identified relevant pathways (PPARα and NF-κB) and targets (such as CXCL1, IL1, TRAF6, TIPARP, and TNFRSF1B) associated with the phenotype of EAD. Preliminary proof of concept gene expression classifiers that distinguish EAD from non-EAD patients, with Area Under the Curve (AUC) >0.80 were also identified. This data may have mechanistic and diagnostic implications for EAD.