The reduced tolerance of rat fatty liver to ischemia reperfusion is associated with mitochondrial oxidative injury

Protective Role of Rapamycin in Fibrotic Liver Ischemia/Reperfusion Injury (C57bl/6 Mouse)

BACKGROUND

Liver ischemia/reperfusion injury (IRI) is a well-documented phenomenon that occurs after liver resection and transplantation, posing a significant clinical challenge. We aim to contribute valuable insights into potential therapeutic interventions for fibrotic liver IRI, ultimately advancing our understanding of liver transplantation and resection outcomes.

METHODS

Twenty-four mice were divided randomly into 4 equal groups: [1] the normal group, n = 6; [2] the liver fibrosis (LF) group, n = 6; [3] the LF and IR group, n = 6; and [4] the LF with treatment of rapamycin and IR group; n = 6.

RESULTS

Key biomarkers assessing liver function, alanine aminotransferase and aspartate aminotransferase, significantly decreased with Rapamycin administration. There is a substantial decrease observed in inflammatory cytokines such as interleukin (IL) 6, IL-1B, tumor necrosis factor alpha, Transforming growth factor-beta (TGF-beta), and Inducible nitric oxide synthase (iNOS) with rapamycin treatment. Furthermore, NOX levels, caspase-3, and caspase-9 were reduced after rapamycin administration.

CONCLUSION

The application of rapamycin demonstrates appropriate effects in anti-inflammation, antioxidation, and anti-apoptosis, indicating significant therapeutic potential for fibrotic liver IRI.

MULTIPLE MACHINE LEARNING METHODS AND COMPARATIVE TRANSCRIPTOMICS IDENTIFY PIVOTAL GENES FOR ISCHEMIA-REPERFUSION INJURY IN HUMAN DONOR TISSUE UNDERGOING ORTHOTOPIC LIVER TRANSPLANTATION

ABSTRACT

Background: Hepatic ischemia-reperfusion injury (HIRI) is a major complication affecting patient prognosis during the period after orthotopic liver transplantation (OLT). Although an increasing number of scientists have investigated the molecular biology of ischemia-reperfusion injury (IRI) during OLT in animal and cellular models in recent years, studies using comprehensive and high-quality sequencing results from human specimens to screen for key molecules are still lacking. Aims: The objective of this study is to explore the molecular biological pathways and key molecules associated with HIRI during OLT through RNA sequencing and related bioinformatics analysis techniques. Methods: The study was done by performing mRNA sequencing on liver tissue samples obtained from 15 cases of in situ liver transplantation patients who experienced ischemia and reperfusion injury within 1 year at Guizhou Medical University, and combined with bioinformatics analysis and machine learning methods, we identified the genes and transcription factors that are closely associated with IRI during in situ liver transplantation surgery. Results: There were 877 differentially expressed genes (DEGs) identified in the included liver samples, of which 817 DEGs were upregulated and 60 were downregulated. Functional enrichment analysis revealed significant enrichment of immune-related terms, such as inflammation, defense responses, responses to cytokines, immune system processes, and cellular activation. In addition, core gene enrichment analysis after cytoHubba screening suggested that liver reperfusion injury might be associated with translation-related elements as a pathway together with protein translation processes. Machine learning with the weighted correlation network analysis screening method identified PTGS2, IRF1, and CDKN1A as key genes in the reperfusion injury process. Conclusions: This study demonstrated that the pathways and genomes whose expression is altered throughout the reperfusion process might be critical for the progression of HIRI during OLT.

SARS-CoV-2 induced liver injury: Incidence, risk factors, impact on COVID-19 severity and prognosis in different population groups

Liver is unlikely the key organ driving mortality in coronavirus disease 2019 (COVID-19) however, liver function tests (LFTs) abnormalities are widely observed mostly in moderate and severe cases. According to this review, the overall prevalence of abnormal LFTs in COVID-19 patients ranges from 2.5% to 96.8% worldwide. The geographical variability in the prevalence of underlying diseases is the determinant for the observed discrepancies between East and West. Multifactorial mechanisms are implicated in COVID-19-induced liver injury. Among them, hypercytokinemia with "bystander hepatitis", cytokine storm syndrome with subsequent oxidative stress and endotheliopathy, hypercoagulable state and immuno-thromboinflammation are the most determinant mechanisms leading to tissue injury. Liver hypoxia may also contribute under specific conditions, while direct hepatocyte injury is an emerging mechanism. Except for initially observed severe acute respiratory distress syndrome corona virus-2 (SARS-CoV-2) tropism for cholangiocytes, more recent cumulative data show SARS-CoV-2 virions within hepatocytes and sinusoidal endothelial cells using electron microscopy (EM). The best evidence for hepatocellular invasion by the virus is the identification of replicating SARS-CoV-2 RNA, S protein RNA and viral nucleocapsid protein within hepatocytes using in-situ hybridization and immunostaining with observed intrahepatic presence of SARS-CoV-2 by EM and by in-situ hybridization. New data mostly derived from imaging findings indicate possible long-term sequelae for the liver months after recovery, suggesting a post-COVID-19 persistent live injury.

Protective effects of curcumin on ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is a term used to describe phenomena connected to the dysfunction of various tissue damage due to reperfusion after ischemic injury. While I/R may result in systemic inflammatory response syndrome or multiple organ dysfunction syndrome, there is still a long way to improve therapeutic outcomes. A number of cellular metabolic and ultrastructural alterations occur by prolonged ischemia. Ischemia increases the expression of proinflammatory gene products and bioactive substances within the endothelium, such as cytokines, leukocytes, and adhesion molecules, even as suppressing the expression of other "protective" gene products and substances, such as thrombomodulin and constitutive nitric oxide synthase (e.g., prostacyclin, nitric oxide [NO]). Curcumin is the primary phenolic pigment derived from turmeric, the powdered rhizome of Curcuma longa. Numerous studies have shown that curcumin has strong antiinflammatory and antioxidant characteristics. It also prevents lipid peroxidation and scavenges free radicals like superoxide anion, singlet oxygen, NO, and hydroxyl. In our study, we highlight the mechanisms of protective effects of curcumin against I/R injury in various organs.

Targeting the Hepatic Microenvironment to Improve Ischemia/Reperfusion Injury: New Insights into the Immune and Metabolic Compartments

Hepatic ischemia/reperfusion injury (IRI) is mainly characterized by high activation of immune inflammatory responses and metabolic responses. Understanding the molecular and metabolic mechanisms underlying development of hepatic IRI is critical for developing effective therapies for hepatic IRI. Recent advances in research have improved our understanding of the pathogenesis of IRI. During IRI, hepatocyte injury and inflammatory responses are mediated by crosstalk between the immune cells and metabolic components. This crosstalk can be targeted to treat or reverse hepatic IRI. Thus, a deep understanding of hepatic microenvironment, especially the immune and metabolic responses, can reveal new therapeutic opportunities for hepatic IRI. In this review, we describe important cells in the liver microenvironment (especially non-parenchymal cells) that regulate immune inflammatory responses. The role of metabolic components in the diagnosis and prevention of hepatic IRI are discussed. Furthermore, recent updated therapeutic strategies based on the hepatic microenvironment, including immune cells and metabolic components, are highlighted.

Hypothermic oxygenated perfusion ameliorates ischemia-reperfusion injury of fatty liver in mice via Brg1/Nrf2/HO-1 axis

BACKGROUND

After cold storage (CS) and subsequent transplantation, fatty liver is more inclined to develop liver dysfunction and serious postoperative complications in contrast to healthy liver. Hypothermic oxygenated perfusion (HOPE) is a safe and efficacious system, which can repair fatty liver and reduce ischemia-reperfusion injury. The aim of this research is to investigate the function of Brg1/Nrf2/HO-1 signaling pathway in the protective effect of HOPE on ischemia-reperfusion injury of fatty liver.

METHODS

The mouse fatty liver model was successfully established and verified by hematoxylin-eosin (HE) staining and oil red O staining. The animals were divided into Control group, CS group and HOPE group. The levels of liver enzyme and lactate in the perfusate were used to measure liver function and cellular metabolism. HE staining and TUNEL staining were utilized to assess the tissue structure and apoptosis, respectively. The levels of superoxide dismutase, malondialdehyde and reactive oxygen species in liver tissue were measured to quantitatively analyze the degree of oxidative stress, and the expressions of protein Brg1, Nrf2 and HO-1 were detected by means of the western blot. Double-labeling immunofluorescence was to explore the colocalization of Brg1 and Nrf2.

RESULTS

The injury of the liver in the CS group was more serious than that in the control group. However, HOPE could significantly reduce the injury, which was manifested by the improvement of liver function and cellular metabolism, and the lower degrees of apoptosis, necrosis and oxidative stress. Furthermore, the expressions of Brg1, Nrf2 and HO-1 in the HOPE group were significantly increased than those in the CS group.

CONCLUSIONS

One-hour HOPE treatment before reperfusion can obviously improve the injury of fatty liver in mice. The underlying mechanism may be that the interaction of Brg1 and Nrf2 can selectively activate the transcription of HO-1.

Non-invasive diagnosis of non-alcoholic fatty liver disease using an algorithm combining clinical indexes and ultrasonographic measures

INTRODUCTION AND OBJECTIVE

Non-Alcoholic Fatty Liver Disease (NAFLD) is a metabolic liver disease related to insulin resistance, which requires invasive methods for diagnosis. The aim of this study was to analyze whether the use of an algorithm involving both clinical indices and hepatic ultrasound measurements improves the accuracy for the non-invasive diagnosis of NAFLD.

PATIENTS AND METHODS

Cross-sectional study with patients undergoing elective cholecystectomy. We collected anthropometric, metabolic, liver biopsy, and liver ultrasonography data. We calculated unpaired t-test and Pearson's coefficient, and areas under the receiver-operating characteristic curves (AUROC) for the Fatty Liver Index (FLI), Lipid Accumulation Product (LAP) indexes, right liver index diameter, and for predictive models constructed with discriminant analysis.

RESULTS

One hundred patients in groups with and without NAFLD. FLI, LAP, right and caudate liver lobe diameters, and congestion index were higher in NAFLD group (p = 0.011, p = 0.011, p = 0.001, p = 0.027, p = 0.009). The right liver lobe diameter had the highest AUROC. Predictive models that combined sensitivity and specificity for the clinical indexes and liver ultrasound had an AUROC over 0.7.

CONCLUSION

The ultrasonography measure of right liver lobe diameter by itself can reliably identify patients with NAFLD with a good sensitivity and specificity, however, this can be improved by adding the LAP mathematical index in our population.

COVID-19 and Indirect Liver Injury: A Narrative Synthesis of the Evidence

The liver is frequently affected by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection. The most common manifestations are mildly elevated alanine aminotransferase and aspartate aminotransferase, with a prevalence of 16-53% among patients. Cases with severe coronavirus disease 2019 (COVID-19) seem to have higher rates of acute liver dysfunction, and the presence of abnormal liver tests at admission signifies a higher risk of severe disease during hospitalization. Patients with chronic liver diseases also have a higher risk of severe disease and mortality (mainly seen in patients with metabolic-associated fatty liver disease). Several pathways of damage have been proposed in the liver involvement of COVID-19 patients; although, the end-cause is most likely multifactorial. Abnormal liver tests have been attributed to the expression of angiotensin-converting enzyme 2 receptors in SARS-CoV-2 infection. This enzyme is expressed widely in cholangiocytes and less in hepatocytes. Other factors attributed to liver damage include drug-induced liver injury, uncontrolled release of proinflammatory molecules ("cytokine storm"), pneumonia-associated hypoxia, and direct damage by the infection. Hepatic steatosis, vascular thrombosis, fibrosis, and inflammatory features (including Kupffer cell hyperplasia) are the most common liver histopathological findings in deceased COVID-19 patients, suggesting important indirect mechanisms of liver damage. In this translational medicine-based narrative review, we summarize the current data on the possible indirect mechanisms involved in liver damage due to COVID-19, the histopathological findings, and the impact of these mechanisms in patients with chronic liver disease.

Contemporary strategies to assess and manage liver donor steatosis: a review

PURPOSE OF REVIEW

Due to a persistent shortage of donor livers, attention has turned toward ways of utilizing marginal grafts, particularly those with steatosis, without incurring inferior outcomes. Here we review the evaluation and utilization of steatotic liver allografts, highlight recently published data, and discuss novel methods of graft rehabilitation.

RECENT FINDINGS

Although severe liver allograft (>60%) steatosis has been associated with inferior graft and recipient outcomes, mild (<30%) steatosis has not. There is ongoing debate regarding safe utilization of grafts with moderate (30-60%) steatosis. Presently, no established protocols for evaluating steatosis in donor candidates or utilizing such grafts exist. Liver biopsy is accepted as the gold standard technique, though noninvasive methods have shown promise in accurately predicting steatosis. More recently, machine perfusion has been shown to enhance ex situ liver function and reduce steatosis, emerging as a potential means of optimizing steatotic grafts prior to transplantation.

SUMMARY

Steatotic liver allografts constitute a large proportion of deceased donor organs. Further work is necessary to define safe upper limits for the acceptable degree of steatosis, develop standardized evaluation protocols, and establish utilization guidelines that prioritize safety. Machine perfusion has shown promise in rehabilitating steatotic grafts and offers the possibility of expanding the deceased donor pool.

New Insights Into the Role of Autophagy in Liver Surgery in the Setting of Metabolic Syndrome and Related Diseases

Visceral obesity is an important component of metabolic syndrome, a cluster of diseases that also includes diabetes and insulin resistance. A combination of these metabolic disorders damages liver function, which manifests as non-alcoholic fatty liver disease (NAFLD). NAFLD is a common cause of abnormal liver function, and numerous studies have established the enormously deleterious role of hepatic steatosis in ischemia-reperfusion (I/R) injury that inevitably occurs in both liver resection and transplantation. Thus, steatotic livers exhibit a higher frequency of post-surgical complications after hepatectomy, and using liver grafts from donors with NAFLD is associated with an increased risk of post-surgical morbidity and mortality in the recipient. Diabetes, another MetS-related metabolic disorder, also worsens hepatic I/R injury, and similar to NAFLD, diabetes is associated with a poor prognosis after liver surgery. Due to the large increase in the prevalence of MetS, NAFLD, and diabetes, their association is frequent in the population and therefore, in patients requiring liver resection and in potential liver graft donors. This scenario requires advancement in therapies to improve postoperative results in patients suffering from metabolic diseases and undergoing liver surgery; and in this sense, the bases for designing therapeutic strategies are in-depth knowledge about the molecular signaling pathways underlying the effects of MetS-related diseases and I/R injury on liver tissue. A common denominator in all these diseases is autophagy. In fact, in the context of obesity, autophagy is profoundly diminished in hepatocytes and alters mitochondrial functions in the liver. In insulin resistance conditions, there is a suppression of autophagy in the liver, which is associated with the accumulation of lipids, being this is a risk factor for NAFLD. Also, oxidative stress occurring in hepatic I/R injury promotes autophagy. The present review aims to shed some light on the role of autophagy in livers undergoing surgery and also suffering from metabolic diseases, which may lead to the discovery of effective therapeutic targets that could be translated from laboratory to clinical practice, to improve postoperative results of liver surgeries when performed in the presence of one or more metabolic diseases.

The Protective Effect of Traditional Chinese Medicine on Liver Ischemia-Reperfusion Injury

Liver ischemia-reperfusion (I/R) injury occurs during transplantation and major hepatic surgery, which may lead to postoperative liver dysfunction. More and more traditional Chinese medicines (TCMs) have been used to treat liver ischemia-reperfusion injury. The purpose of this review is to evaluate the different protective effects of TCMs in the treatment of liver ischemia-reperfusion injury and to summarize its possible mechanisms. The results indicate that TCMs attenuate liver I/R injury via multiple mechanisms, including antioxidation stress, anti-inflammatory response, antiapoptosis, and inhibiting endoplasmic reticulum stress. However, the in-depth mechanism of the protective effects of these traditional Chinese medicines still remains unknown.

Ex-Vivo Pharmacological Defatting of the Liver: A Review

The ongoing organ shortage has forced transplant teams to develop alternate sources of liver grafts. In this setting, ex-situ machine perfusion has rapidly developed as a promising tool to assess viability and improve the function of organs from extended criteria donors, including fatty liver grafts. In particular, normothermic machine perfusion represents a powerful tool to test a liver in full 37 °C metabolism and add pharmacological corrections whenever needed. In this context, many pharmacological agents and therapeutics have been tested to induce liver defatting on normothermic machine perfusion with promising results even on human organs. This systematic review makes a comprehensive synthesis on existing pharmacological therapies for liver defatting, with special focus on normothermic liver machine perfusion as an experimental ex-vivo translational model.

Pathophysiological Changes During Ischemia-reperfusion Injury in Rodent Hepatic Steatosis

BACKGROUND/AIM

Ischemia and reperfusion injuries may produce deleterious effects on hepatic tissue after liver surgery and transplantation. The impact of ischemia-reperfusion injury (IRI) on the liver depends on its substrate, the percentage of liver ischemic tissue subjected to IRI and the ischemia time. The consequences of IRI are more evident in pathologic liver substrates, such as steatotic livers. This review is the result of an extended bibliographic PubMed search focused on the last 20 years. It highlights basic differences encountered during IRI in lean and steatotic livers based on studies using rodent experimental models.

CONCLUSION

The main difference in cell death between lean and steatotic livers is the prevalence of apoptosis in the former and necrosis in the latter. There are also major changes in the effect of intracellular mediators, such as TNFα and IL-1β. Further experimental studies are needed in order to increase current knowledge of IRI effects and relevant mechanisms in both lean and steatotic livers, so that new preventive and therapeutic strategies maybe developed.

Pretreatment with the ALDH2 activator Alda‑1 protects rat livers from ischemia/reperfusion injury by inducing autophagy

Hepatic ischemia/reperfusion injury (HIRI) is a complex pathophysiological process that often leads to poor clinical prognosis. Clinically, the effective means to alleviate HIRI are limited. The aim of the present study was to investigate whether Alda-1, an activator of mitochondrial aldehyde dehydrogenase 2 (ALDH2), had a protective effect on HIRI and to investigate the mechanisms underlying this protective effect. Sprague-Dawley rats were treated with Alda-1 or Daidzin, an ALDH2 inhibitor, 30 min before partial (70%) warm liver ischemia to induce HIRI. The 48 rats were randomly divided into four groups: Sham, ischemia injury (IR), IR-Alda-1, and IR-Daidzin. After 6 and 24 h of reperfusion, serum and liver tissue samples were collected and stored for further experiments. Alanine aminotransferase, aspartate aminotransferase and hematoxylin & eosin staining was used to evaluate the liver damage. Western blotting and reverse transcription-quantitative PCR were used to detect the expression of related proteins and mRNA. TUNEL staining was used to observe the apoptosis of liver cells. Transmission electron microscopy was used to detect the mitochondrial injuries. Alda-1 pretreatment ameliorated the HIRI-induced damage to the liver function and reduced histological lesions. Alda-1 also increased ALDH2 activity after HIRI. Moreover, the pretreatment with Alda-1 reduced the accumulation of toxic aldehyde 4-hydroxy-2-nonenal, decreased the production of reactive oxygen species and malondialdehyde, reversed the damage to the liver mitochondria, attenuated hepatocyte apoptosis and inhibited the HIRI-induced inflammatory response, including high-mobility group box 1/toll-like receptor 4 signaling. Alda-1 also induced autophagy by upregulating autophagy-related 7 and Rab7 increasing the microtubule associated protein 1 light chain 3 αII/I ratio and inhibiting p62 expression. ALDH2-induced autophagy was dependent on the activation of the AKT/mammalian target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) signaling pathways. In conclusion, the findings of the present study suggested that Alda-1 may protect the liver against HIRI-induced damage, including hepatic enzyme injury, acetaldehyde accumulation, oxidative stress, hepatocyte apoptosis and inflammation. Alda-1 may confer this protection by inducing autophagy through the AKT/mTOR and AMPK signaling pathways. Therefore, ALDH2 could represent a potential pharmacological target in the clinical treatment of HIRI.

Hepatic consequences of COVID-19 infection. Lapping or biting?

The outbreak of coronavirus disease 2019 (COVID-19) starting last December in China placed emphasis on liver involvement during infection. This review discusses the underlying mechanisms linking COVID-19 to liver dysfunction, according to recent available information, while waiting further studies. The manifestations of liver damage are usually mild (moderately elevated serum aspartate aminotransferase activities), and generally asymptomatic. Few patients can still develop severe liver problems, and therapeutic options can be limited. Liver dysfunction may affect about one-third of the patients, with prevalence greater in men than women, and in elderly. Mechanisms of damage are complex and include direct cholangiocyte damage and other coexisting conditions such as the use of antiviral drugs, systemic inflammatory response, respiratory distress syndrome-induced hypoxia, sepsis, and multiple organ dysfunction. During new COVID-19 infections, liver injury may be observed. If liver involvement appears during COVID-19 infection, however, attention is required. This is particularly true if patients are older or have a pre-existing history of liver diseases. During COVID-19 infection, the onset of liver damage impairs the prognosis, and hospital stay is longer.

Silibinin treatment results in reducing OPA1&MFN1 genes expression in a rat model hepatic ischemia-reperfusion

The mitochondrial damage has a pivotal role in triggering apoptosis and cell death. This study assessed the effect of silibinin on optical atrophy-1 (OPA1) and mitofusin-1 (MFN1) gene expression in liver tissue during hepatic warm ischemia-reperfusion (IR). Four groups of rats, eight rats each were designed: Vehicle: the rats received normal saline and encountered to laparotomy, Sili: silibinin (60 mg/kg) was administered to animals, IR: the rats received the normal saline and insulted by liver IR procedure, and IR + Sili: silibinin was injected to rats. All groups were subjected to the same process of injection of the solvent or silibinin (30 min before laparotomy or ischemia and immediately after the reperfusion), intraperitoneally (IP). After 3 h of reperfusion, blood and liver tissue samples were collected for future examinations. Our results showed no significant differences between the Vehicle and Sili groups in all assessed parameters. In IR + Sili, the increased serum levels of AST and ALT in comparison with the control group were markedly reduced by silibinin treatment. Silibinin lowered the elevated expression of OPA1 and MFN1 mRNAs in the IR group. Histology revealed silibinin could decline tissue degeneration compared to the IR group. Electron microscopy of control and silibinin groups showed no fusion of mitochondria and tissue degradation both of which were observed in the IR group. The extent of tissue destruction and mitochondrial fusion decreased significantly with silibinin treatment. Silibinin has a protective effect on liver cells against IR induced injuries by preserving mitochondrial membrane.

Hic-5 deficiency attenuates hepatic ischemia reperfusion injury through TLR4/NF-κB signaling pathways

AIM

To explore the role and mechanism of Hydrogen peroxide-inducible clone-5 (Hic-5) in hepatic ischemia reperfusion injury.

METHODS

Hic-5 KO and WT mice were used to establish the liver ischemia reperfusion model (HI/R). Primary hepatocytes were isolated to establish hypoxic reoxygenation model (H/R). AST and ALT were measured by automatic biochemical analyzer. Liver tissue sections were stained with HE and Tunnel. RNA and proteins were extracted from liver tissues, and expressions of Il-6, Il-10, CCL-2, CXCL-10, P65, Caspase-3, TLR4 and FADD were detected at gene and protein levels. Liver cell apoptosis was detected by flow cytometry and immunofluorescence. Primary hepatocytes were stimulated by LPS to establish a model of hepatocyte apoptosis, and cell inflammation and apoptosis-related proteins were detected.

RESULTS

After HI/R, ALT and AST in serum were up-regulated, some hepatocyte apoptosis were observed in pathological sections. Hic-5 expression was increased in WT mice after HI/R, and liver damage were severer than KO mice. The expression of IL-6, CCL-2 and CXCL-10 in the liver of KO mice was low, and the expression of IL-10 was high. Further studies showed that KO mice showed lower expression of P65, Caspase3 and TLR4. In H/R model, hepatocytes also showed the same trend. Finally, after LPS stimulation, the results showed that the inflammation and apoptosis induced by LPS were significantly reduced in Hic-5 knocked hepatocytes.

CONCLUSION

Hic-5 was found to promote inflammation through NF-kb signaling pathway and apoptosis through TLR4-FADD signaling pathway in mice with HI/R, thus aggravating liver injury in mice.

Cellular and molecular mechanisms of liver regeneration: Proliferation, growth, death and protection of hepatocytes

Liver regeneration is an important and necessary process that the liver depends on for recovery from injury. The regeneration process consists of a complex network of cells and organs, including liver cells (parenchymal and non-parenchymal cells) and extrahepatic organs (thyroid, adrenal glands, pancreas, duodenum, spleen, and autonomic nervous system). The regeneration process of a normal, healthy liver depends mainly on hepatocyte proliferation, growth, and programmed cell death. Cell proliferation and growth are regulated in a cooperative manner by interleukin (IL)-6/janus kinase (Jak)/signal transducers and activators of transcription-3 (STAT3), and phosphoinositide 3-kinase (PI3-K)/phosphoinositide-dependent protein kinase 1 (PDK1)/Akt pathways. The IL-6/Jak/STAT3 pathway regulates hepatocyte proliferation and protects against cell death and oxidative stress. The PI3-K/PDK1/Akt pathway is primarily responsible for the regulation of cell size, sending mitotic signals in addition to pro-survival, antiapoptotic and antioxidative signals. Though programmed cell death may interfere with liver regeneration in a pathological situation, it seems to play an important role during the termination phase, even in a normal, healthy liver regeneration. However, further study is needed to fully elucidate the mechanisms regulating the processes of liver regeneration with regard to cell-to-cell and organ-to-organ networks at the molecular and cellular levels.

Inflammasome-Mediated Inflammation in Liver Ischemia-Reperfusion Injury

Ischemia-reperfusion injury is an important cause of liver damage occurring during surgical procedures including hepatic resection and liver transplantation, and represents the main underlying cause of graft dysfunction and liver failure post-transplantation. To date, ischemia-reperfusion injury is an unsolved problem in clinical practice. In this context, inflammasome activation, recently described during ischemia-reperfusion injury, might be a potential therapeutic target to mitigate the clinical problems associated with liver transplantation and hepatic resections. The present review aims to summarize the current knowledge in inflammasome-mediated inflammation, describing the experimental models used to understand the molecular mechanisms of inflammasome in liver ischemia-reperfusion injury. In addition, a clear distinction between steatotic and non-steatotic livers and between warm and cold ischemia-reperfusion injury will be discussed. Finally, the most updated therapeutic strategies, as well as some of the scientific controversies in the field will be described. Such information may be useful to guide the design of better experimental models, as well as the effective therapeutic strategies in liver surgery and transplantation that can succeed in achieving its clinical application.

Rivastigmine prevents injury induced by ischemia and reperfusion in rat liver

PURPOSE

To evaluate whether pre-treatment with rivastigmine is able to attenuate the I/R induced lesions in rat liver.

METHODS

SHAM animals or those submitted to I/R, non-treated or pre-treated with rivastigminine (2mg/kg) either 50 or 15 minutes before ischemia, were used. After I/R protocol, these animals were killed and their livers were harvested to measurement of the mitochondrial swelling as well as the malondialdehyde (MDA), nitrite and nitrate tissue concentration. Blood was also harvested for serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) determinations.

RESULTS

I/R promoted a significant increase of mitochondrial swelling in the studied animals. This increase of mitochondrial swelling was partially prevented by rivastigmine, but only if administered 50 minutes before ischemia. No significant modification of MDA, nitrite or nitrate tissue concentrations was observed in consequence of I/R, followed or not by rivastigmine treatments. In addition, I/R elevated both AST and ALT. These elevations of serum enzymes were not reversed by the different rivastigmine treatments.

CONCLUSIONS

Rivastigmine administered 50 minutes before ischemia attenuates I/R-induced mitochondrial swelling, that indicates liver injury. This protective effect may be related to a greater stimulation of α7nAChR present in the Kupffer cells by the non-methabolized ACh, leading to an attenuation of I/R-induced inflammation.

Computational Modeling of Oxidative Stress in Fatty Livers Elucidates the Underlying Mechanism of the Increased Susceptibility to Ischemia/Reperfusion Injury

QUESTION

Donor liver organs with moderate to high fat content (i.e. steatosis) suffer from an enhanced susceptibility to ischemia/reperfusion injury (IRI) during liver transplantation. Responsible for the cellular injury is an increased level of oxidative stress, however the underlying mechanistic network is still not fully understood.

METHOD

We developed a phenomenological mathematical model of key processes of hepatic lipid metabolism linked to pathways of oxidative stress. The model allows the simulation of hypoxia (i.e. ischemia-like conditions) and reoxygenation (i.e. reperfusion-like conditions) for various degrees of steatosis and predicts the level of hepatic lipid peroxidation (LPO) as a marker of cell damage caused by oxidative stress.

RESULTS & CONCLUSIONS

Our modeling results show that the underlying feedback loop between the formation of reactive oxygen species (ROS) and LPO leads to bistable systems behavior. Here, the first stable state corresponds to a low basal level of ROS production. The system is directed to this state for healthy, non-steatotic livers. The second stable state corresponds to a high level of oxidative stress with an enhanced formation of ROS and LPO. This state is reached, if steatotic livers with a high fat content undergo a hypoxic phase. Theoretically, our proposed mechanistic network would support the prediction of the maximal tolerable ischemia time for steatotic livers: Exceeding this limit during the transplantation process would lead to severe IRI and a considerable increased risk for liver failure.

Ex situ machine perfusion as a tool to recondition steatotic donor livers: Troublesome features of fatty livers and the role of defatting therapies. A systematic review

Long-standing research has shown that increased lipid content in donor livers is associated with inferior graft outcomes posttransplant. The global epidemic that is obesity has increased the prevalence of steatosis in organ donors, to the extent that it has become one of the main reasons for declining livers for transplantation. Consequently, it is one of the major culprits behind the discrepancy between the number of donor livers offered for transplantation and those that go on to be transplanted. Steatotic livers are characterized by poor microcirculation, depleted energy stores because of an impaired capacity for mitochondrial recovery, and a propensity for an exaggerated inflammatory response following reperfusion injury culminating in poorer graft function postoperatively. Ex situ machine perfusion, currently a novel method in graft preservation, is showing great promise in providing a tool for the recovery and reconditioning of marginal livers. Hence, reconditioning these steatotic livers using machine perfusion has the potential to increase the number of liver transplants performed. In this review, we consider the problematic issues associated with fatty livers in the realm of transplantation and discuss pharmacological and nonpharmacological options that are being developed to enhance recovery of these organs using machine perfusion and defatting strategies.

Short-term and long-term outcomes of liver transplantation using moderately and severely steatotic donor livers: A systematic review

BACKGROUND

The aim of this study was to perform a systemic review of the studies addressing the use of moderately and severely steatotic donor livers for liver transplantation.

METHODS

We searched the following electronic databases from January 1, 1989, to August 1, 2017: PubMed, EMBASE, Science Citation Index Expanded, and the Cochrane Library. In addition, reference lists were scanned to identify any additional reports. The quality of published papers was assessed. The main outcomes of the use of moderately and severely steatotic donor livers for liver transplantation, including primary nonfunction, short-term mortality, and long-term mortality, were extracted for pooled analysis.

RESULTS

Literature searches identified 16 studies that met the inclusion criteria. There were no randomized controlled studies, and all of the studies were retrospective or prospective case series. From a total of 3226 subjects (532 moderately and severely steatotic donor livers and 2694 controls), we found a significant increase in primary nonfunction [odds ratio (OR): 2.47, 95% confidence interval (95% CI): 1.44-4.27], and a trend of increase in 1-month patient mortality (OR: 1.90, 95% CI: 0.98-3.71) with the use of moderately and severely steatotic donor livers, whereas the 1-year mortality was relatively less influenced.

CONCLUSION

The use of moderately and severely steatotic livers is associated with unfavorable short-term outcomes, but long-term outcomes are relatively less influenced.

Complement Activation in Liver Transplantation: Role of Donor Macrosteatosis and Implications in Delayed Graft Function

The complement system anchors the innate inflammatory response by triggering both cell-mediated and antibody-mediated immune responses against pathogens. The complement system also plays a critical role in sterile tissue injury by responding to damage-associated molecular patterns. The degree and duration of complement activation may be a critical variable controlling the balance between regenerative and destructive inflammation following sterile injury. Recent studies in kidney transplantation suggest that aberrant complement activation may play a significant role in delayed graft function following transplantation, confirming results obtained from rodent models of renal ischemia/reperfusion (I/R) injury. Deactivating the complement cascade through targeting anaphylatoxins (C3a/C5a) might be an effective clinical strategy to dampen reperfusion injury and reduce delayed graft function in liver transplantation. Targeting the complement cascade may be critical in donor livers with mild to moderate steatosis, where elevated lipid burden amplifies stress responses and increases hepatocyte turnover. Steatosis-driven complement activation in the donor liver may also have implications in rejection and thrombolytic complications following transplantation. This review focuses on the roles of complement activation in liver I/R injury, strategies to target complement activation in liver I/R, and potential opportunities to translate these strategies to transplanting donor livers with mild to moderate steatosis.

PGC-1α Downregulation in Steatotic Liver Enhances Ischemia-Reperfusion Injury and Impairs Ischemic Preconditioning

AIMS

Liver steatosis is associated with mitochondrial dysfunction and elevated reactive oxygen species (ROS) levels together with enhanced sensitivity to ischemia-reperfusion (IR) injury and limited response to preconditioning protocols. Here, we sought to determine whether the downregulation in the steatotic liver of peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α), a master regulator of mitochondrial metabolism and ROS that is known to play a role in liver metabolic control, could be responsible for the sensitivity of the steatotic liver to ischemic damage.

RESULTS

PGC-1α was induced in normal liver after exposure to an IR protocol, which was concomitant with an increase in the levels of antioxidant proteins. By contrast, its induction was severely blunted in the steatotic liver, resulting in a modest induction of antioxidant proteins. Livers of PGC-1α^-/- mice on a chow diet were normal, but they exhibited an enhanced sensitivity to IR injury and also a lack of response to ischemic preconditioning (IPC), a phenotype that recapitulated the features of the steatotic liver in terms of liver damage, although the inflammatory response differed between both models. Utilizing an in vitro model of IPC, we found that PGC-1α expression was downregulated in hepatic cells cultured at 1% O₂; whereas it was induced after reoxygenation (3% O₂), and it was responsible for the recovery of antioxidant gene expression after the ischemic period. Innovation & Conclusion: PGC-1α plays an important role in the protection against IR injury in the liver, which is likely associated with its capacity to induce antioxidant gene expression. Antioxid. Redox Signal. 27, 1332-1346.

Remote ischemic preconditioning protects liver ischemia-reperfusion injury by regulating eNOS-NO pathway and liver microRNA expressions in fatty liver rats

BACKGROUND

Ischemic preconditioning (IPC) is a strategy to reduce ischemia-reperfusion (I/R) injury. The protective effect of remote ischemic preconditioning (RIPC) on liver I/R injury is not clear. This study aimed to investigate the roles of RIPC in liver I/R in fatty liver rats and the involvement of endothelial nitric oxide synthase-nitric oxide (eNOS-NO) pathway and microRNA expressions in this process.

METHODS

A total of 32 fatty rats were randomly divided into the sham group, I/R group, RIPC group and RIPC+I/R group. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and nitric oxide (NO) were measured. Hematoxylin-eosin staining was used to observe histological changes of liver tissues, TUNEL to detect hepatocyte apoptosis, and immunohistochemistry assay to detect heat shock protein 70 (HSP70) expression. Western blotting was used to detect liver inducible NOS (iNOS) and eNOS protein levels and real-time quantitative polymerase chain reaction to detect miR-34a, miR-122 and miR-27b expressions.

RESULTS

Compared with the sham and RIPC groups, serum ALT, AST and iNOS in liver tissue were significantly higher in other two groups, while serum NO and eNOS in liver tissue were lower, and varying degrees of edema, degeneration and inflammatory cell infiltration were found. Cell apoptosis number was slightly lower in the RIPC+I/R group than that in I/R group. Compared with the sham group, HSP70 expressions were significantly increased in other three groups (all P<0.05). Compared with the sham and RIPC groups, elevated miR-34a expressions were found in I/R and RIPC+I/R groups (P<0.05). MiR-122 and miR-27b were found significantly decreased in I/R and RIPC+I/R groups compared with the sham and RIPC groups (all P<0.05).

CONCLUSION

RIPC can reduce fatty liver I/R injury by affecting the eNOS-NO pathway and liver microRNA expressions.

Intermittent Ischemic Preconditioning Protects Against Hepatic Ischemia-Reperfusion Injury and Extensive Hepatectomy in Steatotic Rat Liver

BACKGROUND

Hepatic steatosis causes severe liver damage and has deleterious effects when associated with ischemia-reperfusion mechanisms. Ischemic preconditioning (IPC) protects lean liver against prolonged ischemia by improving micro-circulation and reducing lipid peroxidation. We investigated the effect of intermittent IPC on liver ischemia-reperfusion injury (IRI) and extensive hepatectomy in severe hepatic steatosis.

METHODS

Severe hepatic steatosis was performed by 12-14 weeks of choline-free diet in 108 Wistar rats. We induced 30-minute ischemia-reperfusion manipulations and extensive hepatectomy with or without prior IPC in steatotic livers and after 6 and 24 hours of reperfusion blood transaminases, and IL6, TNFα, NO and Lactate in blood and liver tissue were measured.

RESULTS

Steatotic rats subjected to hepatic ischemia-reperfusion alone after extensive hepatectomy, showed severe liver damage with significantly increased values of AST, ALT, TNFα and Lactate and significantly reduced IL6 and NO, while no one rat survived for more than 29 hours. On the contrary, steatotic rats subjected to intermittent IPC, 24 hours before ischemia-reperfusion, presented increased 30-day survival (67%), lower values of AST, ALT, TNFα and Lactate, and increased IL6 and NO levels. Simple and intermittent IPC manipulations, 1 hour before the IRI and extended hepatectomy, did not prolong survival more than 57 and 98 hours, respectively. Simple IPC, 24 hours before IRI and extended hepatectomy had the lowest possible survival (16.7%).

CONCLUSIONS

Hepatic steatosis and IRI after major liver surgery largely affect morbidity and mortality. Intermittent IPC, 24 hours before IRI and extensive hepatectomy, presents higher 30-day survival and improved liver function parameters.

ROS homeostasis, a key determinant in liver ischemic-preconditioning

Reactive Oxygen Species (ROS) are key mediators of ischemia-reperfusion injury but also required for the induction of the stress response that limits tissue injury and underlies the protection provided by ischemic-preconditioning protocols. Liver steatosis is an important risk factor for liver transplant failure. Liver steatosis is associated with mitochondrial dysfunction and excessive mitochondrial ROS production. Studies aiming at decreasing the sensibility of the steatotic liver to ischemia-reperfusion injury using pre-conditioning protocols, have shown that the steatotic liver has a reduced capacity to respond to these protocols. Recent studies indicate that these effects are related to a reduced capacity of the steatotic liver to respond to elevated ROS levels following reperfusion by inducing a compensatory response. This failure to respond to ROS is associated with reduced levels of antioxidants, mitochondrial damage, hepatocyte cell death, activation of the immune system and induction of pro-fibrotic mediators.

Remote ischemic perconditioning prevents liver transplantation-induced ischemia/reperfusion injury in rats: Role of ROS/RNS and eNOS

AIM

To investigate the underlying mechanisms of the protective role of remote ischemic perconditioning (RIPerC) in rat liver transplantation.

METHODS

Sprague-Dawley rats were subjected to sham, orthotopic liver transplantation (OLT), ischemic postconditioning (IPostC) or RIPerC. After 3 h reperfusion, blood samples were taken for measurement of alanine aminotransferase, aspartate aminotransferase, creatinine (Cr) and creatinine kinase-myocardial band (CK-MB). The liver lobes were harvested for the following measurements: reactive oxygen species (ROS), H₂O₂, mitochondrial membrane potential (ΔΨm) and total nitric oxide (NO). These measurements were determined using an ROS/H₂O₂, JC1 and Total NOx Assay Kit, respectively. Endothelial NO synthase (eNOS) was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and western blotting, and peroxynitrite was semi-quantified by western blotting of 3-nitrotyrosine.

RESULTS

Compared with the OLT group, the grafts subjected to RIPerC showed significantly improved liver and remote organ functions (P < 0.05). ROS (P < 0.001) including H₂O₂ (P < 0.05) were largely elevated in the OLT group as compared with the sham group, and RIPerC (P < 0.05) reversed this trend. The collapse of ΔΨm induced by OLT ischemia/reperfusion (I/R) injury was significantly attenuated in the RIPerC group (P < 0.001). A marked increase of NO content and phosphoserine eNOS, both in protein and mRNA levels, was observed in liver graft of the RIPerC group as compared with the OLT group (P < 0.05). I/R-induced 3-nitrotyrosine content was significantly reduced in the RIPerC group as compared with the OLT group (P < 0.05). There were no significant differences between the RIPerC and IPostC groups for all the results except Cr. The Cr level was lower in the RIPerC group than in the IPostC group (P < 0.01).

CONCLUSION

Liver graft protection by RIPerC is similar to or better than that of IPostC, and involves inhibition of oxidative stress and up-regulation of the PI3K/Akt/eNOS/NO pathway.

Relevance of FXR-p62/SQSTM1 pathway for survival and protection of mouse hepatocytes and liver, especially with steatosis

Background

Liver injury and regeneration involve complicated processes and are affected by various physio-pathological conditions. Surgically, severe liver injury after surgical resection often leads to fatal liver failure, especially with some underlying pathological conditions such as steatosis. Therefore, protection from the injury of hepatocytes and liver is a serious concern in various clinical settings.

Methods

We studied the effects of the farnesoid X receptor (FXR) on cell survival and steatosis in mouse hepatocytes (AML12 mouse liver cells) and investigated their molecular mechanisms. We next studied whether or not FXR improves liver injury, regeneration and steatosis in a mouse model of partial hepatectomy (PH) with steatosis.

Results

An FXR-specific agonist, GW4064, induced expressions of the p62/SQSTM1 gene and protein in AML12 mouse liver cells. Because we previously reported p62/SQSTM1 as a key molecule for antioxidation and cell survival in hepatocytes, we next examined the activation of nuclear factor erythroid 2-related factor-2 (Nrf2) and induction of the antioxidant molecules by GW4064. GW4064 activated Nrf2 and subsequently induced antioxidant molecules (Nrf2, catalase, HO-1, and thioredoxin). We also examined expressions of pro-survival and cell protective molecules associated with p62/SQSTM1. Expectedly, GW4064 induced phosphorylation of Akt, expression of the anti-apoptotic molecules (Bcl-xL and Bcl-2), and reduced harmful hepatic molecules (Fas ligand and Fas). GW4064 promoted hepatocyte survival, which was cancelled by p62/SQSTM1 siRNA. These findings suggest the potential relevance of the FXR-p62/SQSTM1 pathway for the survival and protection of hepatocytes. Furthermore, GW4064 induced the expression of small heterodimer partners (SHP) and suppressed liver X receptor (LXR)-induced steatosis in hepatocytes, expecting the in vivo protective effect of FXR on liver injury especially with steatosis. In the hepatectomy model of db/db mice with fatty liver, pre-treatment by GW4064 significantly reduced post-PH liver injury (serum levels of LDH, AST & ALT and histological study) and improved steatosis. The key molecules, p62/SQSTM1, Nrf2 and SHP were upregulated in fatty liver tissue by GW4064 treatment.

Conclusions

The present study is the first to demonstrate the relevance of FXR-p62/SQSTM1 and -SHP in the protection against injury of hepatocytes and post-PH liver, especially with steatosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-016-0568-3) contains supplementary material, which is available to authorized users.

Liver resection for metastases from colorectal cancer in very elderly patients: New surgical horizons

INTRODUCTION AND AIM

Patients with colorectal cancer (CRC) may develop liver metastases. Surgical resection remains the best treatment of choice for colorectal liver metastases (CRLM) according to resectability criteria, with a long-term survival of 25% up to 41% after 5 years. Advanced age is associated with a higher incidence and co-morbidity, particularly cardiovascular disease, as well as deteriorating physiological reserves. The aim of this study was to analyse the overall and disease-free survival for patients with CRLM according to their chronological age.

METHODS

Patients with CRLM were enrolled in the study. Data on gender, age, co-morbidity, metastasis characteristics (number, size and total metastatic volume (TMV)), use of perioperative chemotherapy and operative and post-operative complications were collected. Then, according to recent World Health Organization (WHO) guidelines, the patients were grouped by age. Statistical analysis was performed using the software R (ver. 2.14.1).

RESULTS

Hepatic resection was performed in 149 patients (21 patients in the very elderly group, 79 in the elderly group and 49 in the younger group). The three groups were comparable in terms of operative duration, transfusion rate, length of high-dependency unit (HDU) stay and post-operative hospital stay. The very elderly group showed a non-significant increase in post-operative morbidity. The 30-day and 60-day/inpatient mortality rates increased with age without any significant statistically difference between the three groups (very elderly group 4.8% and 4.8%; elderly group: 2.5% and 3.8%; and younger group 0% and 2%). At 5 years, the overall survival was 28.6% for very elderly patients (≥75 years), 33.3% for elderly patients (≥65 to <75 years) and 43.5% for younger patients (≤65 years). The 1-, 3- and 5-year disease-free survival was similar across the groups.

CONCLUSIONS

Liver resection for CRLM in carefully selected patients above the age of 75 can be performed with acceptable morbidity and mortality rates, similar to those in younger patients. Moreover, the severity of CRLM in elderly patients is proven to be lesser than in younger patients. Thus, we can conclude that advanced chronological age cannot be considered a contraindication to hepatic resection for CRLM.

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.

Steatotic livers are susceptible to normothermic ischemia-reperfusion injury from mitochondrial Complex-I dysfunction

AIM: To assess the effects of ischemic preconditioning (IPC, 10-min ischemia/10-min reperfusion) on steatotic liver mitochondrial function after normothermic ischemia-reperfusion injury (IRI).

METHODS: Sixty male Sprague-Dawley rats were fed 8-wk with either control chow or high-fat/high-sucrose diet inducing > 60% mixed steatosis. Three groups (n = 10/group) for each dietary state were tested: (1) the IRI group underwent 60 min partial hepatic ischemia and 4 h reperfusion; (2) the IPC group underwent IPC prior to same standard IRI; and (3) sham underwent the same surgery without IRI or IPC. Hepatic mitochondrial function was analyzed by oxygraphs. Mitochondrial Complex-I, Complex-II enzyme activity, serum alanine aminotransferase (ALT), and histological injury were measured.

RESULTS: Steatotic-IRI livers had a greater increase in ALT (2476 ± 166 vs 1457 ± 103 IU/L, P < 0.01) and histological injury following IRI compared to the lean liver group. Steatotic-IRI demonstrated lower Complex-I activity at baseline [78.4 ± 2.5 vs 116.4 ± 6.0 nmol/(min.mg protein), P < 0.001] and following IRI [28.0 ± 6.2 vs 104.3 ± 12.6 nmol/(min.mg protein), P < 0.001]. Steatotic-IRI also demonstrated impaired Complex-I function post-IRI compared to the lean liver IRI group. Complex-II activity was unaffected by hepatic steatosis or IRI. Lean liver mitochondrial function was unchanged following IRI. IPC normalized ALT and histological injury in steatotic livers but had no effect on overall steatotic liver mitochondrial function or individual mitochondrial complex enzyme activities.

CONCLUSION: Warm IRI impairs steatotic liver Complex-I activity and function. The protective effects of IPC in steatotic livers may not be mediated through mitochondria.

Evaluation of Liver Ischemia-Reperfusion Injury in Rabbits Using a Nanoscale Ultrasound Contrast Agent Targeting ICAM-1

OBJECTIVE

To assess the feasibility of ultrasound molecular imaging in the early diagnosis of liver ischemia-reperfusion injury (IRI) using a nanoscale contrast agent targeting anti-intracellular adhesion molecule-1 (anti-ICAM-1).

METHODS

The targeted nanobubbles containing anti-ICAM-1 antibody were prepared using the avidin-biotin binding method. Human hepatic sinusoidal endothelial cells (HHSECs) were cultured at the circumstances of hypoxia/reoxygenation (H/R) and low temperature. The rabbit liver IRI model (I/R group) was established using the Pringle's maneuver. The time-intensity curve of the liver contrast ultrasonographic images was plotted and the peak intensity, time to peak, and time of duration were calculated.

RESULTS

The size of the targeted nanobubbles were 148.15 ± 39.75 nm and the concentration was 3.6-7.4 × 109/ml, and bound well with the H/R HHSECs. Animal contrast enhanced ultrasound images showed that the peak intensity and time of duration of the targeted nanobubbles were significantly higher than that of common nanobubbles in the I/R group, and the peak intensity and time of duration of the targeted nanobubbles in the I/R group were also significantly higher than that in the SO group.

CONCLUSION

The targeted nanobubbles have small particle size, stable characteristic, and good targeting ability, which can assess hepatic ischemia-reperfusion injury specifically, noninvasively, and quantitatively at the molecular level.

A direct comparison of methods used to measure oxidized glutathione in biological samples: 2-vinylpyridine and N-ethylmaleimide

The ratio of glutathione disulfide (GSSG) to reduced glutathione (GSH) in biological samples is a frequently used parameter of oxidative stress. As a result, many methods are developed to measure GSSG. The most popular and convenient of these relies on enzymatic cycling following the chemical masking of GSH in the sample using 2-vinylpyridine (2VP). However, 2VP is a slow reactant and its use may result in artificially high GSSG values due to oxidation of the sample over time. Fast-reacting reagents such as N-ethylmaleimide (NEM) may provide more accurate results. We performed a direct comparison of methods using 2VP and NEM. With 2VP, the percentage of total glutathione (GSH+GSSG) in the oxidized form was significantly higher in all tested tissues (kidney, lung and liver) compared to the same procedure performed using NEM. We conclude that NEM, when coupled with a simple solid-phase extraction procedure, is more accurate for the determination of GSSG. We also tested the effects of various handling and storage conditions on GSSG. A detailed description and a discussion of other methods are also included.

Effects of steatosis on hepatic hemodynamics in patients with metabolic syndrome

The aim of our study was to assess the hemodynamic changes in hepatic and splenic circulation using B-mode ultrasonography and color Doppler ultrasonography, in a population of patients with metabolic syndrome divided with respect to the presence or absence of steatosis diagnosed by ultrasonography. One hundred forty-one patients were included in the study. The severity of non-alcoholic fatty liver disease was classified as mild, moderate or severe. Visceral fat thickness, longitudinal diameter of the spleen, diameter of the portal vein, mean maximum portal vein flow velocity, hepatic artery and splenic artery resistivity indexes and hepatic vein flow phasicity were measured. Non-alcoholic fatty liver disease was detected in 114 of 141 patients, with a prevalence of 80.8%. Patients with steatosis had significantly greater diameters of the portal vein, longitudinal diameters of the spleen, visceral fat thickness and hepatic artery and splenic artery resistivity indexes, whereas their portal vein flow velocities were significantly lower. Non-alcoholic fatty liver disease severity correlated positively with diameter of the portal vein, longitudinal diameter of the spleen and visceral fat thickness and negatively with hepatic artery and splenic artery resistivity indexes and reduced hepatic vein flow phasicity. Our patients with metabolic syndrome and non-alcoholic fatty liver disease had a flattened hepatic vein flow phasicity, greater portal vein diameter, reduction in portal vein flow velocity and intrahepatic arterial vasodilation. The vasodilation of the intrahepatic arterial system was likely activated both by the effect of insulin resistance and as a physiologic adaptation to restore hepatic flow. The increase in spleen volume might be related to the organomegaly typical of obese patients.

p62/SQSTM1 plays a protective role in oxidative injury of steatotic liver in a mouse hepatectomy model

AIMS

Liver injury and regeneration involve complicated processes and are affected by various physio-pathological factors. We investigated the mechanisms of steatosis-associated liver injury and delayed regeneration in a mouse model of partial hepatectomy.

RESULTS

Initial regeneration of the steatotic liver was significantly delayed after hepatectomy. Although hepatocyte proliferation was not significantly suppressed, severe liver injury with oxidative stress (OS) occurred immediately after hepatectomy in the steatotic liver. Fas-ligand (FasL)/Fas expression was upregulated in the steatotic liver, whereas the expression of antioxidant and anti-apoptotic molecules (catalase/MnSOD/Ref-1 and Bcl-2/Bcl-xL/FLIP, respectively) and p62/SQSTM1, a steatosis-associated protein, was downregulated. Interestingly, pro-survival Akt was not activated in response to hepatectomy, although it was sufficiently expressed even before hepatectomy. Suppression of p62/SQSTM1 increased FasL/Fas expression and reduced nuclear factor erythroid 2-related factor-2 (Nrf-2)-dependent antioxidant response elements activity and antioxidant responses in steatotic and nonsteatotic hepatocytes. Exogenously added FasL induced severe cellular OS and necrosis/apoptosis in steatotic hepatocytes, with only the necrosis being inhibited by pretreatment with antioxidants, suggesting that FasL/Fas-induced OS mainly leads to necrosis. Furthermore, p62/SQSTM1 re-expression in the steatotic liver markedly reduced liver injury and improved liver regeneration.

INNOVATION

This study is the first which demonstrates that reduced expression of p62/SQSTM1 plays a crucial role in posthepatectomy acute injury and delayed regeneration of steatotic liver, mainly via redox-dependent mechanisms.

CONCLUSION

In the steatotic liver, reduced expression of p62/SQSTM1 induced FasL/Fas overexpression and suppressed antioxidant genes, mainly through Nrf-2 inactivation, which, along with the hypo-responsiveness of Akt, caused posthepatectomy necrotic/apoptotic liver injury and delayed regeneration, both mainly via a redox-dependent mechanism.

Hepatic ischemia and reperfusion injury: effects on the liver sinusoidal milieu

Ischemia-reperfusion injury is an important cause of liver damage occurring during surgical procedures including hepatic resection and liver transplantation, and represents the main underlying cause of graft dysfunction post-transplantation. Cellular and biochemical processes occurring during hepatic ischemia-reperfusion are diverse and complex, and include the deregulation of the healthy phenotype of all liver cellular components. Nevertheless, a significant part of these processes are still unknown or unclear. The present review aims at summarizing the current knowledge in liver ischemia-reperfusion, but specifically focusing on liver cell phenotype and paracrine interaction deregulations. Moreover, the most updated therapeutic strategies including pharmacological, genetic and surgical interventions, as well as some of the scientific controversies in the field will be described. Finally, the importance of considering the subclinical situation of liver grafts when translating basic knowledge to the bedside is discussed.

The impact of hepatic steatosis on hepatic ischemia-reperfusion injury in experimental studies: a systematic review

Background. The impact of hepatic steatosis on outcome following hepatic ischemia-reperfusion injury (IRI) remains controversial with conflicting clinical results. A number of experimental studies have been published examining the relationship between hepatic steatosis and IRI. This systematic review evaluates these experimental studies. Methods. An electronic search of the Medline and Embase databases (January 1946 to June 2012) was performed to identify studies that reported relevant outcomes in animal models of hepatic steatosis subjected to IRI. Results. A total of 1314 articles were identified, of which 33 met the predefined criteria and were included in the study. There was large variation in the type of animal model, duration, and type of IRI and reporting of histological findings. Increased macrovesicular steatosis (>30%) was associated with increased histological damage, liver function derangement, and reduced survival. Increased duration of warm or cold ischemia had a negative impact on all outcomes measured. Microvesicular steatosis did not influence outcome. Conclusions. Findings from this systemic review support the hypothesis that livers with >30% macrovesicular steatosis are less tolerant of IRI. Clinically, it is likely that these findings are applicable to patients undergoing hepatic resection, but further studies are required to confirm these data.

Current knowledge on oxidative stress in hepatic ischemia/reperfusion

Ischemia/reperfusion (I/R) injury associated with hepatic resections and liver transplantation remains a serious complication in clinical practice, despite several attempts to solve the problem. The redox balance, which is pivotal for normal function and integrity of tissues, is dysregulated during I/R, leading to an accumulation of reactive oxygen species (ROS). Formation of ROS and oxidant stress are the disease mechanisms most commonly invoked in hepatic I/R injury. The present review examines published results regarding possible sources of ROS and their effects in the context of I/R injury. We also review the effect of oxidative stress on marginal livers, which are more vulnerable to I/R-induced oxidative stress. Strategies to improve the viability of marginal livers could reduce the risk of dysfunction after surgery and increase the number of organs suitable for transplantation. The review also considers the therapeutic strategies developed in recent years to reduce the oxidative stress induced by hepatic I/R, and we seek to explain why some of them have not been applied clinically. New antioxidant strategies that have yielded promising results for hepatic I/R injury are discussed.

Role of glycogen synthase kinase 3β in protective effect of propofol against hepatic ischemia-reperfusion injury

BACKGROUND

It was previously reported that propofol, an intravenously administered hypnotic and anesthetic agent, protects organs from ischemia-reperfusion (I/R) injury. However, the underlying mechanisms are largely unknown. Glycogen synthase kinase 3β (GSK-3β) is known to play an important role in the oxidative stress-induced apoptosis. In this study, we investigated the role of GSK-3β and mitochondrial permeability transition pore (MPTP) in the protective effects of propofol against hepatic I/R injury.

MATERIALS AND METHODS

The left and median hepatic artery and the portal vein branches were blocked by no-damage artery clips to create the model of partial ischemia (70%), and liver lobes were subjected to warm ischemia for 30, 60, 90 min, respectively. Reperfusion of 120 min was then initiated by the removal of clamp. The MPTP opening was assessed by measuring mitochondrial large amplitude swelling and mitochondrial membrane potential.

RESULTS

Pretreatment with propofol in conditions of hepatic I/R inhibits the apoptosis of hepatocytes as evidenced by decreased terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells. Importantly, propofol suppressed the mitochondrial GSK-3β by promoting or preserving its phosphorylation at Ser9, thus restraining the opening of MPTP and preventing the mitochondrial swell and mitochondrial membrane potential collapse.

CONCLUSIONS

Propofol protects liver from I/R injury by sustaining the mitochondrial function, which is possibly involved with the modulation of MPTP and GSK-3β.

Tauroursodeoxycholic acid affects PPARγ and TLR4 in Steatotic liver transplantation

Numerous steatotic livers are discarded for transplantation because of their poor tolerance to ischemia-reperfusion (I/R). We examined whether tauroursodeoxycholic acid (TUDCA), a known inhibitor of endoplasmic reticulum (ER) stress, protects steatotic and nonsteatotic liver grafts preserved during 6 h in University of Wisconsin (UW) solution and transplanted. The protective mechanisms of TUDCA were also examined. Neither unfolded protein response (UPR) induction nor ER stress was evidenced in steatotic and nonsteatotic liver grafts after 6 h in UW preservation solution. TUDCA only protected steatotic livers grafts and did so through a mechanism independent of ER stress. It reduced proliferator-activated receptor-γ (PPARγ) and damage. When PPARγ was activated, TUDCA did not reduce damage. TUDCA, which inhibited PPARγ, and the PPARγ antagonist treatment up-regulated toll-like receptor 4 (TLR4), specifically the TIR domain-containing adaptor inducing IFNβ (TRIF) pathway. TLR4 agonist treatment reduced damage in steatotic liver grafts. When TLR4 action was inhibited, PPARγ antagonists did not protect steatotic liver grafts. In conclusion, TUDCA reduced PPARγ and this in turn up-regulated the TLR4 pathway, thus protecting steatotic liver grafts. TLR4 activating-based strategies could reduce the inherent risk of steatotic liver failure after transplantation.

The current state of knowledge of hepatic ischemia-reperfusion injury based on its study in experimental models

The present review focuses on the numerous experimental models used to study the complexity of hepatic ischemia/reperfusion (I/R) injury. Although experimental models of hepatic I/R injury represent a compromise between the clinical reality and experimental simplification, the clinical transfer of experimental results is problematic because of anatomical and physiological differences and the inevitable simplification of experimental work. In this review, the strengths and limitations of the various models of hepatic I/R are discussed. Several strategies to protect the liver from I/R injury have been developed in animal models and, some of these, might find their way into clinical practice. We also attempt to highlight the fact that the mechanisms responsible for hepatic I/R injury depend on the experimental model used, and therefore the therapeutic strategies also differ according to the model used. Thus, the choice of model must therefore be adapted to the clinical question being answered.

Melatonin protects steatotic and nonsteatotic liver grafts against cold ischemia and reperfusion injury

Chronic organ-donor shortage has required the acceptance of steatotic livers for transplantation purposes despite the higher risk of graft dysfunction or nonfunction associated with the cold ischemia-reperfusion injury. This study evaluated the use of melatonin as an additive to Institute Georges Lopez (IGL-1) solution for protecting nonsteatotic and steatotic liver grafts against cold ischemia-reperfusion injury. In the current investigation, we used an ex vivo isolated perfused rat liver model. Steatotic and nonsteatotic livers were preserved for 24 hr (4°C) in University of Wisconsin or IGL-1 solutions with or without melatonin, as well as in University of Wisconsin solution alone. Thereafter, livers were subjected to 2-hr reperfusion (37°C). We assessed hepatic injury (transaminases) and function [bile production and sulfobromophthalein (BSP) clearance, vascular resistance], as well as other factors potentially implicated in the high vulnerability of steatotic livers against ischemia-reperfusion injury (oxidative stress and related inflammatory mediators including nitric oxide and cytokines). We also evaluated well-known cytoprotective factors as hemeoxygenase 1 (HO-1). Fatty livers preserved in IGL-1 solution enriched with melatonin showed lower transaminase levels and higher bile production and BSP clearance when compared to those obtained for livers maintained in IGL-1 solution alone. A significant diminution of vascular resistance was also observed when melatonin was added to the IGL-1 solution. The melatonin benefits correlated with the generation of nitric oxide (through constitutive e-NOS activation) and the prevention of oxidative stress and inflammatory cytokine release including tumor necrosis factor and adiponectin, respectively. The addition of melatonin to IGL-1 solution improved nonsteatotic and steatotic liver graft preservation, limiting their risk against cold ischemia-reperfusion injury.

Noncirrhotic human nonalcoholic fatty liver disease induces portal hypertension in relation to the histological degree of steatosis

INTRODUCTION

We earlier showed in an animal model that steatosis, in the absence of fibrosis or inflammation, induces a significant rise in portal pressure. The relevance of these findings for human pathology is unknown till date.

AIMS

To study portal pressure in nonalcoholic fatty liver disease patients and to identify factors possibly related to steatosis-induced changes in liver haemodynamics.

MATERIALS AND METHODS

Patients presenting with a problem of overweight and with noninvasive signs of liver involvement were proposed for transjugular liver biopsy. The biopsy was scored according to the Nonalcoholic Steatohepatitis Clinical Research Network scoring system.

RESULTS

Fifty consecutive patients were studied. Mean age was 47.9 ± 13.6 years; 31 (62%) of them were female. Hepatic venous pressure gradient (HVPG) was normal in 27 patients (54%), borderline (5 mmHg) in nine (18%) and elevated in 14 patients (28%). For further analysis those with a HVPG of 5 mmHg were considered normal (group 1). HVPG was 8.8 ± 2.6 mmHg in those with an elevated HVPG (group 2) versus 3.4 ± 1.2 mmHg in group 1 (P < 0.0001). In both the groups, only one patient had cirrhosis; 26 of 36 (group 1) and nine of 14 patients (group 2) had fibrosis score 0. Fibrosis score was not significantly different (P = 0.530). Perisinusoidal fibrosis score was not significantly different (P = 0.186). Steatosis was the only histological feature that significantly differed between the groups (P = 0.016). The degree of steatosis (P = 0.010) was the only independent predictor of the presence of portal hypertension.

CONCLUSION

Human nonalcoholic fatty liver disease can, even in the absence of significant fibrosis, induce portal hypertension, correlated with the severity of the steatosis.

Indirubin-3'-oxime prevents hepatic I/R damage by inhibiting GSK-3beta and mitochondrial permeability transition

Indirubin-3'-oxime is an indirubin analogue that shows favorable inhibitory activity targeting glycogen synthase kinase 3beta (GSK-3beta). In this study, we evaluated if acute treatment with indirubin-3'-oxime (Ind) prevents hepatic ischemia/reperfusion (I/R) damage. Wistar rats were subjected to 150 min of 70% warm ischemia and 16 h of reperfusion. In the treated group 1 microM indirubin-3'-oxime was administered in the hepatic artery 30 min before ischemia. Acute treatment with Ind decreased serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) levels, comparatively to I/R livers. Bax translocation to the mitochondria and cytochrome c release were higher in I/R livers. Ind treatment significantly attenuated Bax translocation and preserved mitochondrial cytochrome c content. Ind also protected mitochondria from calcium-induced mitochondrial permeability transition (MPT), as well as the decrease in state 3 mitochondrial respiration, the delay in the repolarization after a phosphorylative cycle and the decrease in ATP content caused by I/R. By addressing GSK-3beta activity and phosphorylated GSK-3beta at Ser(9) content in liver homogenates and isolated mitochondria, data suggests that inhibition of GSK-3beta by indirubin-3'-oxime prevents the increase in mitochondrial phosphorylated GSK-3beta at Ser(9) induced by I/R, thus correlating with MPT inhibition and preservation of cytochrome c content. Pre-treatment with indirubin-3'-oxime in conditions of hepatic I/R, protects the liver by maintaining mitochondrial function and hepatic energetic balance.

Non-alcoholic steatohepatitis induces non-fibrosis-related portal hypertension associated with splanchnic vasodilation and signs of a hyperdynamic circulation in vitro and in vivo in a rat model

INTRODUCTION

Steatosis, without fibrosis, may lead to changes in liver blood flow, which are poorly understood, and to date have not been correlated to portal pressure and related haemodynamics.

AIMS

To study the temporal relation between progressive steatosis, portal pressure, systemic haemodynamics, vascular responsiveness, mesenteric and portal blood flow in methionine-choline-deficient diet (MCDD)-fed rats.

METHODS

Male Wistar rats fed the MCDD were examined at week (w) 0-1-2-3-4-5-6-7-8, respectively, including systemic haemodynamics and portal pressure. At w0-4-8, in vivo blood flow was measured in the portal vein and the superior mesenteric artery. Dose-response curves to phenylephrine (PE) were established in abdominal aortic rings.

RESULTS

Histology showed 100% steatosis from w3 on. Fibrosis was absent. Significant inflammation was nearly absent upon w4. Portal pressure slightly increased at w2, reached a maximum at w4 [9.4 +/- 0.3 vs 2.9 +/- 0.6 mmHg at w0 (P=0.003)] and remained stable upon w8. Mean arterial blood pressure (MABP) decreased from w2 on [98.7 +/- 5.7 mmHg on w4 compared with 123.8 +/- 1.8 on w0 (P=0.002)]. Portal flow increased from 1.85 +/- 0.11 to 3.07 +/- 0.44 ml/min/100 g on w0 and w8 respectively (P=0.039). Mesenteric artery flow increased from 3.40 +/- 0.26 to 4.56 +/- 0.30 ml/min/100 g on w0 and w8 respectively (P=0.043). Vascular responsiveness to PE gradually decreased from 138 +/- 3% on w0 to 110 +/- 5% on w4 (P=0.013).

CONCLUSION

Steatohepatitis induces significant portal hypertension (PHT) in the absence of fibrosis, associated with an increase in mesenteric arterial and portal venous flow, arterial hyporesponsiveness to vasoconstrictors and a decrease in MABP, indicating the presence of splanchnic vasodilation and hyperdynamic circulation. These alterations resemble those seen in cirrhotic PHT.

Protective effect of reduced glutathione and venous systemic oxygen persufflation on rat steatotic graft following liver transplantation

BACKGROUND

The aim of this study is to explore the protective effect of high-dose reduced glutathione (GSH) preconditioning and venous systemic oxygen persufflation (VSOP) on rat steatotic liver grafts following transplantation.

METHODS

Steatotic liver model was established by feeding rats a high-fat, high-cholesterol diet, and infusing stomach with 50% alcohol (1 mL/100g body weight/d) for 6 wk. In the pretreated group, short-term and high-dose of GSH administration and VSOP were performed. In rat orthotopic liver transplantation model, the recipient survival, liver function, hepatic microcirculation blood flow, hepatic redox, hepatocytes apoptosis and necrosis, and hepatic ultrastructure alteration were observed.

RESULTS

In the pretreated rat steatotic grafts, hepatic GSH (from 29.43 +/- 4.83 to 41.56 +/- 8.51mg/mgprot), superoxide dismutase (SOD) (from 48.32 +/- 6.27 to 67.74 +/- 7.68 NU/mgprot), and adenosine triphosphate (ATP) (from 1.61 +/- 0.20 to 2.28 +/- 0.09 micromoles/g) were significantly increased (P < 0.05), whereas malondialdehyde (MDA) was significantly decreased (from 7.20 +/- 2.18 to 4.63 +/- 0.58 nmol/mgprot, P < 0.05). The hepatocyte necrosis of fatty liver graft was significantly reduced in the pretreated group when compared with non-treated fatty ones (37.71% +/- 9.69% versus 16.63% +/- 5.53%; t = 3.777, P = 0.014), and significantly improved liver function and hepatic ultrastructure were observed in the pretreated fatty liver group after operation. The animal survival after transplanted with fatty liver was significantly improved (chi(2) = 4.07, P = 0.0436).

CONCLUSION

A short course pretreatment with high-dose GSH and oxygen persufflation during cold preservation effectively protect steatotic liver grafts from ischemic damage and significantly improve early survival rate in a rat fatty liver transplantation model.