Ischemic Preconditioning Increases the Tolerance of Fatty Liver to Hepatic Ischemia-Reperfusion Injury in the Rat (original) (raw)
The effects of vascular bed expansion in steatotic rat liver graft viability
Transplant International, 2004
Disturbed microcirculation caused by fat accumulation in hepatocytes has been implicated in poor graft preservation and reperfusion. The aim of this study was to investigate the effect of vascular bed expansion F B E ) during cold preservation in graft survival Moderate liver steatosis in male Wistar rats (240-280 g) was induced by cholinedeficient diet. Normal, steatotic or VBE-pretreated steatotic grafts were transplanted after 1 h or 9 h of cold preservation. Graft viability was determined by 7-day survival, serum liver enzymes, plasma tumour necrosis factor (TNF)-a, interleukin (IL)-6, and malondialdehyde (MDA) levels. Post-reperfusion bile flow and liver histology were also examined. After 9 h of preservation, VBE-pretreated steatotic liver grafts were associated with significantly
Journal of Biomedicine and Biotechnology, 2012
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.
Liver Transplantation, 2012
Steatotic livers show increased hepatic damage and impaired regeneration after partial hepatectomy (PH) under ischemia/ reperfusion (I/R), which is commonly applied in clinical practice to reduce bleeding. The known function of retinol-binding protein 4 (RBP4) is to transport retinol in the circulation. We examined whether modulating RBP4 and/or retinol could protect steatotic and nonsteatotic livers in the setting of PH under I/R. Steatotic and nonsteatotic livers from Zucker rats were subjected to PH (70%) with 60 minutes of ischemia. RBP4 and retinol levels were measured and altered pharmacologically, and their effects on hepatic damage and regeneration were studied after reperfusion. Decreased RBP4 levels were observed in both liver types, whereas retinol levels were reduced only in steatotic livers. RBP4 administration exacerbated the negative consequences of liver surgery with respect to damage and liver regeneration in both liver types. RBP4 affected the mobilization of retinol from steatotic livers, and this revealed actions of RBP4 independent of simple retinol transport. The injurious effects of RBP4 were not due to changes in retinol levels. Treatment with retinol was effective only for steatotic livers. Indeed, retinol increased hepatic injury and impaired liver regeneration in nonsteatotic livers. In steatotic livers, retinol reduced damage and improved regeneration after surgery. These benefits of retinol were associated with a reduced accumulation of hepatocellular fat. Thus, strategies based on modulating RBP4 could be ineffective and possibly even harmful in both liver types in the setting of PH under I/R. In terms of clinical applications, a retinol pretreatment might open new avenues for liver surgery that specifically benefit the steatotic liver.
Severe liver steatosis correlates with nitrosative and oxidative stress in rats
European Journal of Clinical Investigation, 2008
Background Little is known about nitric oxide (NO) metabolism and redox changes with hepatocyte adipocytic transformation. The aims of this study were to investigate the changes occurring in plasma and hepatic NO metabolites and redox balance in a rat experimental model of simple fatty liver, and to relate plasma with hepatic and mitochondrial changes at different degrees of steatosis.
Liver international : official journal of the International Association for the Study of the Liver, 2008
Liver failure is a dreaded and often fatal complication that sometimes follows a partial hepatic resection. This article reviews the definition, incidence, pathogenesis, risk factors, risk assessment, prevention, clinical features and treatment of post-resectional liver failure (PLF). A systematic, computerized search was performed using key words related to 'partial hepatic resection' and 'liver failure' to review most relevant literature about PLF published in the last 20 years. The reported incidence of PLF ranges between 0.7 and 9.1%. An inadequate quantity or quality of residual liver mass are key events in its pathogenesis. Major risk factors are the presence of comorbid conditions, pre-existent liver disease and small remnant liver volume (RLV). It is essential to identify these risk factors during the pre-operative assessment that includes evaluation of liver volume, anatomy and function. Preventive measures should be applied whenever possible as curative tre...
Enhanced iNOS Gene Expression in the Steatotic Rat Liver after Normothermic Ischemia
European Surgical Research, 2007
nately in hepatocytes with fatty degeneration. A mild increase in mRNA levels for ET-1 was found in steatotic rat livers. I/R induced a further increase in ET-1 gene expression in some but not all reperfused steatotic livers. Conclusions: We show an enhanced gene expression of iNOS in postischemic steatotic rat livers. Hepatocytes with fatty degeneration appear to be the major source for NO generation. Furthermore, I/R may also induce ET-1 gene expression. Dysregulation of sinusoidal perfusion by NO and ET-1 is therefore likely to contribute to I/R injury of the steatotic liver.
Liver Transplantation, 2005
Ischemic preconditioning (IPC) has the potential to decrease graft injury and morbidity after liver transplantation. We prospectively investigated the safety and efficacy of 5 minutes of IPC induced by hilar clamping in local deceased donor livers randomized 1 : 1 to standard (STD) recovery (N ؍ 28) or IPC (N ؍ 34). Safety was assessed by measurement of heart rate, blood pressure, and visual inspection of abdominal organs during recovery, and efficacy by recipient aminotransferases aspartate aminotransferase [AST] and alanine aminotransferase [ALT], both measured in U/L), total bilirubin, and international normalized ratio of prothrombin time (INR) after transplantation. IPC performed soon after laparotomy did not cause hemodynamic instability or visceral congestion. Recipient median AST, median ALT, and mean INR, in STD vs. IPC were as follows: day 1 AST 696 vs. 841 U/L; day 3 AST 183 vs. 183 U/L; day 1 ALT 444 vs. 764 U/L; day 3 ALT 421 vs. 463 U/L; day 1 INR 1.7 ؎ .4 vs. 2.0 ؎ .8; and day 3 INR 1.3 ؎ .2 vs. 1.4 ؎ .3; all P > .05. No instances of nonfunction occurred. The 6-month graft and patient survival STD vs. IPC were 82 vs. 91% and median hospital stay was 10 vs. 8 days; both P > .05. In conclusion, deceased donor livers tolerated 5 minutes of hilar clamping well, but IPC did not decrease graft injury. Further trials with longer periods of preconditioning such as 10 minutes are needed. (Liver Transpl 2005; 11:196-202.)
Liver International, 2012
Ischaemia reperfusion (IR) injury is a clinical entity with a major contribution to the morbidity and mortality of liver surgery and transplantation. A central pathway of protection against IR injury utilizes nitric oxide (NO). Nitric oxide synthase (NOS) enzymes manufacture NO from L-arginine. NO generated by the endothelial NOS (eNOS) isoform protects against liver IR injury, whereas inducible NOS (iNOS)-derived NO may have either a protective or a deleterious effect during the early phase of IR injury, depending on the length of ischaemia, length of reperfusion and experimental model. In late phase hepatic IR injury, iNOS-derived NO plays a protective role. In addition to NOS consumption of L-arginine during NO synthesis, this amino acid may also be metabolized by arginase, an enzyme whose release is increased during prolonged ischaemia, and therefore diverts L-arginine away from NOS metabolism leading to a drop in the rate of NO synthesis. NO most commonly acts through the soluble guanylyl cyclase-cyclic GMPprotein kinase G pathway to ameliorate hepatic IR injury. Both endogenously generated and exogenously administered NO donors protect against liver IR injury. The beneficial effects of NO on liver IR are not, however, universal, and certain conditions, such as steatosis, may influence the protective effects of NO. In this review, the evidence for, and mechanisms of these protective actions of NO are discussed, and areas in need of further research are highlighted.
Hepatology, 2004
Fatty liver, formerly associated predominantly with excessive alcohol intake, is now also recognized as a complication of obesity and an important precursor state to more severe forms of liver pathology including ischemidreperfusion injury. No standard protocol for treating fatty liver exists at this time. We therefore examined the effects of 10 days of interleukin 6 (IL-6) injection in 3 murine models of fatty liver: leptin deficient ob/ob mice, ethanol-fed mice, and mice fed a high-fat diet. In all 3 models, IL-6 injection decreased steatosis and normalized serum aminotransferase. The beneficial effects of IL-6 treatment in vivo resulted in part from an increase in mitochondrial p oxidation of fatty acid and an increase in hepatic export of triglyceride and cholesterol. However, administration of IL-6 to isolated cultured steatotic hepatocytes failed to decrease lipid contents, suggesting that the beneficial effects of I L 6 in vivo do not result from its effects on hepatocytes alone. IL-6 treatment increased hepatic peroxisome proliferator-activated receptor (PPAR) a and decreased liver and serum tumor necrosis factor (TNF) a. Finally, 10 days of treatment with IL-6 prevented the susceptibility of fatty livers to warm ischemidreperfusion injury. In conclusion, long-term IL-6 administration ameliorates fatty livers and protects against warm ischemidreperfusion fatty liver injury, suggesting the therapeutic potential of IL-6 in treating human fatty liver disease.
New Paradigms in Post-hepatectomy Liver Failure
Journal of Gastrointestinal Surgery, 2013
Introduction Liver failure after hepatectomy remains the most feared postoperative complication. Many risk factors are already known, related to patient's comorbidities, underlying liver disease, received treatments and type of resection. Preoperative assessment of functional liver reserve must be a priority for the surgeon. Methods Physiopathology of post-hepatectomy liver failure is not comparable to fulminant liver failure. Liver regeneration is an early phenomenon whose cellular mechanisms are beginning to be elucidated and allowing most of the time to quickly recover a functional organ. In some cases, microscopic and macroscopic disorganization appears. The hepatocyte hyperproliferation and the asynchronism between hepatocytes and non-hepatocyte cells mitosis probably play a major role in this pathogenesis. Results Many peri-or intra-operative techniques try to prevent the occurrence of this potentially lethal complication, but a better understanding of involved mechanisms might help to completely avoid it, or even to extend the possibilities of resection. Conclusion Future prevention and management may include pharmacological slowing of proliferation, drug or physical modulation of portal flow to reduce shear-stress, stem cells or immortalized hepatocytes injection, and liver bioreactors. Everything must be done to avoid the need for transplantation, which remains today the most efficient treatment of liver failure.
Ischaemic preconditioning in transplantation and major resection of the liver
British Journal of Surgery, 2005
Background: Ischaemia-reperfusion injury (IRI) contributes significantly to the morbidity and mortality of transplantation and major resection of the liver. Its severity is reduced by ischaemic preconditioning (IP), the precise mechanisms of which are not completely understood. This review discusses the pathophysiology and role of IP in this clinical setting.
Role of neutrophils in acute inflammatory liver injury
Liver International, 2006
Hepatic infiltration of polymorphonuclear leukocytes (neutrophils) is an early response to tissue injury, cellular stress or systemic inflammation. Neutrophil activation is vital for host-defense and the removal of cell debris but can also cause additional tissue damage or even liver failure. In order to prevent the detrimental effects of neutrophils without compromising hostdefense reactions, it is important to understand the mechanisms of neutrophil hepatotoxicity. The first step in the pathophysiology is the priming and recruitment of neutrophils into the liver vasculature by inflammatory mediators, e.g. cytokines, chemokines, or complement factors. Most critical for parenchymal cell damage is the accumulation in sinusoids, which does not depend on cellular adhesion molecules. The next step is the extravasation into the parenchyma. This process requires a chemotactic signal from hepatocytes or already extravasated neutrophils and depends on cellular adhesion molecules on neutrophils (b 2 or b 1 integrins) and on endothelial cells (intercellular or vascular cell adhesion molecules). The third step is the direct contact with target cells (hepatocytes), which involves b 2 integrins and triggers the full activation of the neutrophil with a long-lasting adherencedependent oxidant stress and degranulation. The oxidants diffuse into hepatocytes and trigger an intracellular oxidant stress, mitochondrial dysfunction and eventually cause oncotic necrotic cell death. Neutrophilderived proteases facilitate extravasation and are involved in the regulation of inflammatory mediator production. Based on these mechanisms, it appears that strengthening of the intracellular defense mechanisms in hepatocytes may be the most promising therapeutic approach to selectively prevent neutrophil-mediated tissue damage without compromising their host-defense function.
Is Ischemic Preconditioning a Useful Strategy in Steatotic Liver Transplantation?
American Journal of Transplantation, 2004
This study examined the effect of preconditioning on steatotic livers for transplantation and attempted to identify the underlying protective mechanisms. Blood flow alterations, neutrophil accumulation, tumor necrosis factor a release and lipid peroxidation were observed in nonsteatotic livers after transplantation. Steatotic and nonsteatotic liver grafts were similar in their blood flow, neutrophil accumulation, and TNF release after transplantation. However, in the presence of steatosis, lipid peroxidation and hepatic injury increased. In addition, recipients of steatotic liver grafts were more vulnerable to lung damage associated with transplantation. The conversion of xanthine dehydrogenase to xanthine oxidase and the accumulation of xanthine during cold ischemia was greater in steatotic than in nonsteatotic liver grafts. The results obtained with xanthine oxidase inhibitors indicated that xanthine/xanthine oxidase could be responsible for the increased lipid peroxidation as well as the exacerbated liver and lung damage associated with transplantation of steatotic livers. Preconditioning reduced the xanthine accumulation and percentage of xanthine oxidase seen in steatotic liver grafts during cold ischemia, and conferred protection against liver and lung damage following transplantation. The benefits of preconditioning could be mediated by nitric oxide. These findings suggest that preconditioning could be a relevant new strategy to protect against the inherent risk of steatotic liver failure following transplantation. L. Fernàndez and E. Carrasco-Chaumel contributed equally to this work.
Role of FGF15 in Hepatic Surgery in the Presence of Tumorigenesis: Dr. Jekyll or Mr. Hyde?
Cells
The pro-tumorigenic activity of fibroblast growth factor (FGF) 19 (FGF15 in its rodent orthologue) in hepatocellular carcinoma (HCC), as well as the unsolved problem that ischemia-reperfusion (IR) injury supposes in liver surgeries, are well known. However, it has been shown that FGF15 administration protects against liver damage and regenerative failure in liver transplantation (LT) from brain-dead donors without tumor signals, providing a benefit in avoiding IR injury. The protection provided by FGF15/19 is due to its anti-apoptotic and pro-regenerative properties, which make this molecule a potentially beneficial or harmful factor, depending on the disease. In the present review, we describe the preclinical models currently available to understand the signaling pathways responsible for the apparent controversial effects of FGF15/19 in the liver (to repair a damaged liver or to promote tumorigenesis). As well, we study the potential pharmacological use that has the activation or i...
Acta Cirurgica Brasileira, 2011
To investigate whether a third generation colloid, hydroxyethyl starch (HES 130/0.4), used for perioperative fluid therapy, protects the rat liver against the late-phase response of ischemia/reperfusion injury (IRI) and if inhibition of neutrophil hepatic infiltration plays a part in this mechanism. METHODS: Wistar rats were used (8 in each group). Three groups had IRI induced by lobar vascular occlusion (60 minutes) and reperfusion (24 hours) and received HES (13 mL/kg iv), 7.5% saline (HS) (13 mL/kg iv) or no fluid. Three other groups were shamoperated and received the same fluid as the test groups. After 24 hours of reperfusion, blood was drawn for alanine aminotransferase (ALT) quantification and ischemic liver samples were taken for histological study (hematoxylin and eosin and chloroacetate staining of neutrophils). RESULTS: HES treatment attenuated the elevation in serum ALT (P=0.001) and reduced the extent of hepatocellular necrosis (P<0.01) compared with the IRI controls. HES-mediated cytoprotection was associated with a decrease of infiltration of neutrophils in the necrotic areas (P<0.05) compared with the untreated IRI rats, but not with the volume control IRI rats (P>0.05). CONCLUSION: Hydroxyethyl starch suppresses inflammatory response and ameliorates the late-phase response of hepatic ischemia/ reperfusion injury.
International journal of molecular sciences, 2018
Institute Goeorges Lopez 1 (IGL-1) and Histidine-Tryptophan-Ketoglutarate (HTK) preservation solutions are regularly used in clinical for liver transplantation besides University of Wisconsin (UW) solution and Celsior. Several clinical trials and experimental works have been carried out comparing all the solutions, however the comparative IGL-1 and HTK appraisals are poor; especially when they deal with the underlying protection mechanisms of the fatty liver graft during cold storage. Fatty livers from male obese Zücker rats were conserved for 24 h at 4 °C in IGL-1 or HTK preservation solutions. After organ recovery and rinsing of fatty liver grafts with Ringer Lactate solution, we measured the changes in mechanistic target of rapamycin (mTOR) signaling activation, liver autophagy markers (Beclin-1, Beclin-2, LC3B and ATG7) and apoptotic markers (caspase 3, caspase 9 and TUNEL). These determinations were correlated with the prevention of liver injury (aspartate and alanine aminostra...
Metabolic Flux Distribution during Defatting of Steatotic Human Hepatoma (HepG2) Cells
Metabolites, 2016
Methods that rapidly decrease fat in steatotic hepatocytes may be helpful to recover severely fatty livers for transplantation. Defatting kinetics are highly dependent upon the extracellular medium composition; however, the pathways involved are poorly understood. Steatosis was induced in human hepatoma cells (HepG2) by exposure to high levels of free fatty acids, followed by defatting using plain medium containing no fatty acids, or medium supplemented with a cocktail of defatting agents previously described before. We measured the levels of 28 extracellular metabolites and intracellular triglyceride, and fed the data into a steady-state mass balance model to estimate strictly intracellular fluxes. We found that during defatting, triglyceride content decreased, while beta-oxidation, the tricarboxylic acid cycle, and the urea cycle increased. These fluxes were augmented by defatting agents, and even more so by hyperoxic conditions. In all defatting conditions, the rate of extracellu...
Antioxidants, 2022
The need to meet the demand for transplants entails the use of steatotic livers, more vulnerable to ischemia-reperfusion (IR) injury. Therefore, finding the optimal composition of static cold storage (SCS) preservation solutions is crucial. Given that ROS regulation is a therapeutic strategy for liver IR injury, we have added increasing concentrations of PEG35 and glutathione (GSH) to the preservation solutions (IGL-1 and IGL-2) and evaluated the possible protection against energy depletion and oxidative stress. Fatty livers from obese Zücker rats were isolated and randomly distributed in the control (Sham) preserved (24 h at 4 °C) in IGL-0 (without PEG35 and 3 mmol/L GSH), IGL-1 (1 g/L PEG35, and 3 mmol/L GSH), and IGL-2 (5 g/L PEG35 and 9 mmol/L GSH). Energy metabolites (ATP and succinate) and the expression of mitochondrial oxidative phosphorylation complexes (OXPHOS) were determined. Mitochondrial carrier uncoupling protein 2 (UCP2), PTEN-induced kinase 1 (PINK1), nuclear factor...
The impact of cortisol in steatotic and non-steatotic liver surgery
Journal of Cellular and Molecular Medicine, 2017
The intent of this study was to examine the effects of regulating cortisol levels on damage and regeneration in livers with and without steatosis subjected to partial hepatectomy under ischaemia-reperfusion. Ultimately, we found that lean animals undergoing liver resection displayed no changes in cortisol, whereas cortisol levels in plasma, liver and adipose tissue were elevated in obese animals undergoing such surgery. Such elevations were attributed to enzymatic upregulation, ensuring cortisol production, and downregulation of enzymes controlling cortisol clearance. In the absence of steatosis, exogenous cortisol administration boosted circulating cortisol, while inducing clearance of hepatic cortisol, thus maintaining low cortisol levels and preventing related hepatocellular harm. In the presence of steatosis, cortisol administration was marked by a substantial rise in intrahepatic availability, thereby exacerbating tissue damage and regenerative failure. The injurious effects of cortisol were linked to high hepatic acethylcholine levels. Upon administering an a7 nicotinic acethylcholine receptor antagonist, no changes in terms of tissue damage or regenerative lapse were apparent in steatotic livers. However, exposure to an M3 muscarinic acetylcholine receptor antagonist protected livers against damage, enhancing parenchymal regeneration and survival rate. These outcomes for the first time provide new mechanistic insight into surgically altered steatotic livers, underscoring the compelling therapeutic potential of cortisol-acetylcholine-M3 muscarinic receptors.
The Role of Neuregulin-1 in Steatotic and Non-Steatotic Liver Transplantation from Brain-Dead Donors
Biomedicines
Background. Brain death (BD) and steatosis are key risk factors to predict adverse post-transplant outcomes. We investigated the role of Neuregulin-1 (NRG1) in rat steatotic and non-steatotic liver transplantation (LT) from brain death donors (DBD). Methods: NRG1 pathways were characterized after surgery. Results: NRG1 and p21-activated kinase 1 (PAK1) levels increased in steatotic and non-steatotic grafts from DBDs. The abolishment of NRG1 effects reduced PAK1. When the effect of either NRG1 nor PAK1 was inhibited, injury and regenerative failure were exacerbated. The benefits of the NRG-1-PAK1 axis in liver grafts from DBDs were associated with increased vascular endothelial growth factor-A (VEGFA) and insulin growth factor-1 (IGF1) levels, respectively. Indeed, VEGFA administration in non-steatotic livers and IGF1 treatment in steatotic grafts prevented damage and regenerative failure resulting from the inhibition of either NRG1 or PAK-1 activity in each type of liver. Exogenous ...
American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons, 2015
High-mobility group box 1 (HMGB1) has been described in different inflammatory disorders, and the deleterious effects of brain death (BD) may counteract the protection conferred by ischemic preconditioning (IP), the only surgical strategy that is being applied in clinical liver transplantation. Our study examined how HMGB1 may affect preconditioned and unpreconditioned steatotic and nonsteatotic liver grafts from donors after BD (DBDs) for transplantation. HMGB1 was pharmacologically modulated in liver grafts from DBDs, and HMGB1-underlying mechanisms were characterized. We found that BD decreased HMGB1 in preconditioned and unpreconditioned livers and was associated with inflammation and damage. Exogenous HMGB1 in DBDs activates phosphoinositide-3-kinase and Akt and reduces hepatic inflammation and damage, increasing the survival of recipients. Combination of IP and exogenous HMGB1 shows additional benefits compared with HMGB1 alone. This study provides new mechanistic insights int...