Acute liver failure: a critical appraisal of available animal models

Preparation and Characterisation of Liposomes of Bergenia Ciliata Extract and Evaluation of their Hepatoprotective Activity

Acute liver damage (ALD) can cause biochemical and pathological changes, which can lead to major complications and even death. The goal of the study was to examine the therapeutic efficacy of liposomes of Bergenia ciliata extract against thioacetamide-induced liver damage in rats. Liposomal batches of B. ciliata extract were prepared by altering the kind and amount of phospholipids and characterized through various physiochemical properties such as laser diffraction, TEM, encapsulation efficiency, stability and in-vitro release studies. In-vivo hepatoprotective studies were performed on TAA-induced acute hepatic damage model. Further, in-silico studies of bergenin against the three hepatic damage markers viz. TGF-β1, TNF-α and interleukin-6 were also performed. Laser diffraction and TEM showed that most stable liposome batch of B. ciliata extract were in the range of 678-1170 nm with encapsulation efficiency of 84.3±3.5. Extract was found to be rapidly dissociated from B. ciliata liposomes in HCl than PBS, according to in-vitro release data. In-vivo data revealed a significant decline in LFT indicators, amelioration of pathological changes and high bergenin bioavailability in the liposomal group. Protective activity of bergenin against ALD targets like TGF-β1, TNF-α and interleukin-6 was anticipated via molecular docking research. As a result, the current findings of the study indicate that B. ciliata liposomes and bergenin have promising ameliorative potential in the management of ALD.

Extracellular vesicles as potential biomarkers and treatment options for liver failure: A systematic review up to March 2022

Introduction

Extracellular vesicles (EVs) carrying functional cargoes are emerging as biomarkers and treatment strategies in multiple liver diseases. Nevertheless, the potential of EVs in liver failure remains indistinct. In this systematic review, we comprehensively analyzed the potential of EVs as biomarkers of liver failure and the therapeutic effects and possible mechanisms of EVs for liver failure.

Methods

We conducted a systematic review by comprehensively searching the following electronic databases: PubMed, Web of Science, Embase and Cochrane Central Register of Controlled Trials from inception to March 2022. The used text words (synonyms and word variations) and database-specific subject headings included "Extracellular Vesicles", "Exosomes", "Liver Failure", "Liver Injury", etc.

Results

A total of 1479 studies were identified. After removing 680 duplicate studies and 742 irrelevant studies, 57 studies were finally retained and analyzed. Fourteen studies revealed EVs with functional cargoes could be used to make the diagnosis of liver failure and provide clues for early warning and prognostic assessment of patients with liver failure. Forty-three studies confirmed the administration of EVs from different sources alleviated hepatic damage and improved survival through inhibiting inflammatory response, oxidative stress as well as apoptosis or promoting hepatocyte regeneration and autophagy.

Conclusions

EVs and their cargoes can be used not only as superior biomarkers of early warning, early diagnosis and prognostic assessments for liver failure, but also as potentially effective treatment options for liver failure. In the future, large-scale studies are urgently needed to verify the diagnostic, predictive and therapeutic value of EVs for liver failure.

Preclinical models of acute liver failure: a comprehensive review

Acute liver failure is marked by the rapid deterioration of liver function in a previously well patient over period of days to weeks. Though relatively rare, it is associated with high morbidity and mortality. This makes it a challenging disease to study clinically, necessitating reliance on preclinical models as means to explore pathophysiology and novel therapies. Preclinical models of acute liver failure are artificial by nature, and generally fall into one of three categories: surgical, pharmacologic or immunogenic. This article reviews preclinical models of acute liver failure and considers their relevance in modeling clinical disease.

Phosphorylated‑myosin light chain mediates the destruction of small intestinal epithelial tight junctions in mice with acute liver failure

Tight junction dysregulation and epithelial damage contribute to intestinal barrier loss in patients with acute liver failure (ALF); however, the regulatory mechanisms of these processes remain poorly understood. The aim of the present study was to investigate the changes of intestinal tight junction and intestinal mucosa in mice with ALF and their mechanisms. In the present study, ALF was induced in mice through an intraperitoneal injection of D-galactosamine and lipopolysaccharide (D-GalN/LPS), and the morphological changes of the liver or small intestine were analyzed using hematoxylin and eosin staining, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The intestinal tissues and isolated serum were analyzed using western blotting, immunofluorescence staining and ELISA. D-GalN/LPS-induced mice exhibited signs of hepatocyte necrosis, alongside inflammatory cell infiltration into the liver tissue and partial microvilli detachment in the small intestinal mucosa. TEM demonstrated that the intestinal epithelial tight junctions were impaired, whereas SEM micrographs revealed the presence of abnormal microvilli in D-GalN/LPS-induced mice. In addition, the expression levels of phosphorylated (p)-myosin light chain (MLC), MLC kinase (MLCK) and Rho-associated kinase (ROCK) were significantly increased in the D-GalN/LPS-induced mice compared with those in the control mice, whereas the subsequent inhibition of MLCK or ROCK significantly reduced p-MLC expression levels. Conversely, the expression levels of occludin and zonula occludens-1 (ZO-1) were significantly decreased in the D-GalN/LPS-induced mice, and the inhibition of MLCK or ROCK significantly increased occludin and ZO-1 protein expression levels compared with those in the control group. Changes in the serum levels of tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 were similar to the trend observed in p-MLC expression levels. In conclusion, the findings of the present study suggested that in a D-GalN/LPS-induced ALF model, TNF-α and IL-6 signaling may increase MLCK and ROCK expression levels, further mediate phosphorylation of MLC, which may result in tight junction dysregulation and intestinal barrier dysfunction.

Applications of Nanobiomaterials in the Therapy and Imaging of Acute Liver Failure

This review focuses on the therapeutic mechanisms, targeting strategies of various nanomaterials in acute liver failure, and recent advances of diverse nanomaterials for acute liver failure therapy, diagnosis, and imaging. This review provides an outlook on the applications of nanomaterials, especially on the new horizons in acute liver failure therapy, and inspires broader interests across various disciplines. Acute liver failure (ALF), a fatal clinical disease featured with overwhelming hepatocyte necrosis, is a grand challenge in global health. However, a satisfactory therapeutic option for curing ALF is still absent, other than liver transplantation. Nanobiomaterials are currently being developed for the diagnosis and treatment of ALF. The liver can sequester most of nanoparticles from blood circulation, which becomes an intrinsic superiority for nanobiomaterials targeting hepatic diseases. Nanobiomaterials can enhance the bioavailability of free drugs, thereby significantly improving the therapeutic effects in ALF. Nanobiomaterials can also increase the liver accumulation of therapeutic agents and enable more effective targeting of the liver or specific liver cells. In addition, stimuli-responsive, optical, or magnetic nanomaterials exhibit great potential in the therapeutical, diagnostic, and imaging applications in ALF. Therefore, therapeutic agents in combination with nanobiomaterials increase the specificity of ALF therapy, diminish adverse systemic effects, and offer a multifunctional theranostic platform. Nanobiomaterial holds excellent significance and prospects in ALF theranostics. In this review, we summarize the therapeutic mechanisms and targeting strategies of various nanobiomaterials in ALF. We highlight recent developments of diverse nanomedicines for ALF therapy, diagnosis, and imaging. Furthermore, the challenges and future perspectives in the theranostics of ALF are also discussed.

Circulating monocytes accelerate acute liver failure by IL-6 secretion in monkey

Acute liver failure (ALF) is associated with high mortality, and a poor understanding of the underlying pathophysiology has resulted in a lack of effective treatments so far. Here, using an amatoxin‐induced rhesus monkey model of ALF, we panoramically revealed the cellular and molecular events that lead to the development of ALF. The challenged monkeys with toxins underwent a typical course of ALF including severe hepatic injury, systemic inflammation and eventual death. Adaptive immune was not noticeably disturbed throughout the progress of ALF. A systematic examination of serum factors and cytokines revealed that IL‐6 increase was the most rapid and drastic. Interestingly, we found that IL‐6 was mainly produced by circulating monocytes. Furthermore, ablation of monocyte‐derived IL‐6 in mice decreased liver injury and systemic inflammation following chemical injection. Our findings reveal a critical role of circulating monocytes in initiating and accelerating ALF, indicating a potential therapeutic target in clinical treatment for ALF.

Ratio of Creatine Kinase to Alanine Aminotransferase as a Biomarker of Acute Liver Injury in Dystrophinopathy

Objective

To investigate the ratios of creatine kinase (CK) to aminotransferases as biomarkers of acute liver injury in dystrophinopathy.

Methods

C57 and mdx (dystrophic) mice were treated with a hepatotoxic reagent D-galactosamine (D-GalN). The degrees of liver and muscle injury were assessed using histological examinations. To examine whether serum CK-adjusted aminotransferase levels could indicate liver status in dystrophic mice, the CK/alanine aminotransferase (ALT) and CK/aspartate aminotransferase (AST) ratios were analyzed. Furthermore, we enrolled 658 male patients with dystrophinopathy and 378 male patients without muscle and liver injury as control, whose serum ALT, AST, and CK levels were examined.

Results

Animal experiments indicated that D-GalN treatment could induce acute liver injury but not muscle injury. Additionally, D-GalN decreased the CK/ALT and CK/AST ratios in both C57 mice and mdx mice (P < 0.001). However, there was an overlap of the CK/AST ratio between dystrophic mice with and without acute liver injury. In patients with dystrophinopathy, CK-adjusted ALT diminished the variability associated with age, genotype, clinical phenotype, and motor function (P > 0.05).

Conclusions

CK/ALT is a potential biomarker for the differential evaluation of acute liver injury in dystrophic mice, which highlights the value to further evaluate the practice of CK/ALT in dystrophinopathy patients.

A clinical-scale BioArtificial Liver, developed for GMP, improved clinical parameters of liver function in porcine liver failure

Liver failure, whether arising directly from acute liver failure or from decompensated chronic liver disease is an increasing problem worldwide and results in many deaths. In the UK only 10% of individuals requiring a liver transplant receive one. Thus the need for alternative treatments is paramount. A BioArtificial Liver machine could temporarily replace the functions of the liver, buying time for the patient's liver to repair and regenerate. We have designed, implemented and tested a clinical-scale BioArtificial Liver machine containing a biomass derived from a hepatoblastoma cell-line cultured as three dimensional organoids, using a fluidised bed bioreactor, together with single-use bioprocessing equipment, with complete control of nutrient provision with feedback BioXpert recipe processes, and yielding good phenotypic liver functions. The methodology has been designed to meet specifications for GMP production, required for manufacture of advanced therapy medicinal products (ATMPs). In a porcine model of severe liver failure, damage was assured in all animals by surgical ischaemia in pigs with human sized livers (1.2-1.6 kg liver weights). The BioArtificial liver (UCLBAL) improved important prognostic clinical liver-related parameters, eg, a significant improvement in coagulation, reduction in vasopressor requirements, improvement in blood pH and in parameters of intracranial pressure (ICP) and oxygenation.

Proteomic Signature of Acute Liver Failure: From Discovery and Verification in a Pig Model to Confirmation in Humans

Acute liver failure (ALF) is a fatal condition hallmarked by rapid development. The present study aimed to describe the dynamic alterations of serum proteins associated with ALF development, and to seek for novel biomarkers of ALF. Miniature pigs (n = 38) were employed to establish ALF models by infusing d-galactosamine (GALN, 1.3 g/kg). A total of 1310 serum proteins were compared in pooled serum samples (n = 10) before and 36 h after GALN administration through label-free quantitation (LFQ) based shotgun proteomics. Functional analysis suggested a significant enrichment of ALF-related proteins involved in energy metabolism. Temporal changes of 20 energy metabolism related proteins were investigated in individual pigs (n = 8) via parallel reaction monitoring (PRM) based targeted proteomics. In addition, mitochondrion degeneration and gene expression alteration of aerobic metabolism genes were confirmed in GALN-insulted pig liver. In clinical validation study enrolled 34 ALF patients and 40 healthy controls, fructose-1,6-bisphosphatase 1 (FBP1) showed a prognostic value for short-term survival (30 days) equal to that of the Model of End-stage Liver Disease score (ROC-AUC = 0.778). Survival analysis suggested significantly higher death-related hazard in ALF patients with higher FBP1 levels (>16.89 μg/dL) than in those with lower FBP1 levels (p = 0.002). Additionally, serum retinol binding protein 4 (RBP4) level was found decreased prior to ALT elevation in GALN-insulted pig model. We also confirmed that serum level of RBP4 is significantly lower in ALF patients (p < 0.001) as compared with healthy controls. In summary, this translational study, displayed by multistaged proteomics techniques, unveiled underlying functional changes related to the development of ALF and facilitated the discovery of novel ALF markers.

Precision medicine in rare disease: Mechanisms of disparate effects of N-carbamyl-l-glutamate on mutant CPS1 enzymes

This study documents the disparate therapeutic effect of N-carbamyl-l-glutamate (NCG) in the activation of two different disease-causing mutants of carbamyl phosphate synthetase 1 (CPS1). We investigated the effects of NCG on purified recombinant wild-type (WT) mouse CPS1 and its human corresponding E1034G (increased ureagenesis on NCG) and M792I (decreased ureagenesis on NCG) mutants. NCG activates WT CPS1 sub-optimally compared to NAG. Similar to NAG, NCG, in combination with MgATP, stabilizes the enzyme, but competes with NAG binding to the enzyme. NCG supplementation activates available E1034G mutant CPS1 molecules not bound to NAG enhancing ureagenesis. Conversely, NCG competes with NAG binding to the scarce M792I mutant enzyme further decreasing residual ureagenesis. These results correlate with the respective patient's response to NCG. Particular caution should be taken in the administration of NCG to patients with hyperammonemia before their molecular bases of their urea cycle disorders is known.

Concise Review: Liver Regenerative Medicine: From Hepatocyte Transplantation to Bioartificial Livers and Bioengineered Grafts

Donor organ shortage is the main limitation to liver transplantation as a treatment for end-stage liver disease and acute liver failure. Liver regenerative medicine may in the future offer an alternative form of therapy for these diseases, be it through cell transplantation, bioartificial liver (BAL) devices, or bioengineered whole organ liver transplantation. All three strategies have shown promising results in the past decade. However, before they are incorporated into widespread clinical practice, the ideal cell type for each treatment modality must be found, and an adequate amount of metabolically active, functional cells must be able to be produced. Research is ongoing in hepatocyte expansion techniques, use of xenogeneic cells, and differentiation of stem cell-derived hepatocyte-like cells (HLCs). HLCs are a few steps away from clinical application, but may be very useful in individualized drug development and toxicity testing, as well as disease modeling. Finally, safety concerns including tumorigenicity and xenozoonosis must also be addressed before cell transplantation, BAL devices, and bioengineered livers occupy their clinical niche. This review aims to highlight the most recent advances and provide an updated view of the current state of affairs in the field of liver regenerative medicine. Stem Cells 2017;35:42-50.

Experimental models of hepatotoxicity related to acute liver failure

Acute liver failure can be the consequence of various etiologies, with most cases arising from drug-induced hepatotoxicity in Western countries. Despite advances in this field, the management of acute liver failure continues to be one of the most challenging problems in clinical medicine. The availability of adequate experimental models is of crucial importance to provide a better understanding of this condition and to allow identification of novel drug targets, testing the efficacy of new therapeutic interventions and acting as models for assessing mechanisms of toxicity. Experimental models of hepatotoxicity related to acute liver failure rely on surgical procedures, chemical exposure or viral infection. Each of these models has a number of strengths and weaknesses. This paper specifically reviews commonly used chemical in vivo and in vitro models of hepatotoxicity associated with acute liver failure.

Endozepine-4 levels are increased in hepatic coma

AIM

To evaluate the serum levels of endozepine-4, their relation with ammonia serum levels, the grading of coma and the severity of cirrhosis, in patients with hepatic coma.

METHODS

In this study we included 20 subjects with Hepatic coma, 20 subjects with minimal hepatic encephalopathy (MHE) and 20 subjects control. All subjects underwent blood analysis, Child Pugh and Model for End - stage liver disease (MELD) assessment, endozepine-4 analysis.

RESULTS

Subjects with hepatic coma showed significant difference in endozepine-4 (P < 0.001) and NH3 levels (P < 0.001) compared both to MHE and controls patients. Between NH3 and endozepine-4 we observed a significant correlation (P = 0.009; Pearson correlation 0.570). There was a significant correlation between endozepine-4 and MELD (P = 0.017; Pearson correlation = 0.529). In our study blood ammonia concentration was noted to be raised in patients with hepatic coma, with the highest ammonia levels being found in those who were comatose. We also found a high correlation between endozepine-4 and ammonia (P < 0.001). In patients with grade IV hepatic coma, endozepine levels were significantly higher compared to other groups.

CONCLUSION

This study suggests that an increased level of endozepine in subjects with higher levels of MELD was observed. In conclusion, data concerning involvement of the GABA-ergic system in HE coma could be explained by stage-specific alterations.

New Tools in Experimental Cellular Therapy for the Treatment of Liver Diseases

The current standard of care for end stage liver disease is orthotopic liver transplantation (OLT). Through improvement in surgical techniques, immunosuppression, and general medical care, liver transplantation has become an effective treatment over the course of the last half-century. Unfortunately, due to the limited availability of donor organs, there is a finite limit to the number of patients who will benefit from this therapy. This review will discuss current research in experimental cellular therapies for acute, chronic, and metabolic liver failure that may be appropriate when liver transplantation is not an immediate option.

The brain in acute on chronic liver failure

Acute-on-chronic liver failure (ACLF) is a newly defined clinical entity with significant morbidity and mortality (~40-90% at 1 year dependent on need for organ support at presentation). It defines a presentation with acute severe liver injury, often with multiorgan dysfunction, on a background of previously known or unknown cirrhosis. In its severest form, it is almost indistinguishable from acute liver failure, as similarly in around 5% may rapidly progress to intracranial hypertension and cerebral oedema culminating in coma and/or death. Our understanding of such cerebral sequelae is currently limited to clinical observation, though our knowledge base is rapidly expanding since recent consensus clinical definition and guidance. Moreover, there are now animal models of ACLF and imaging modalities to better characterize events in the brain that occur with ACLF. However, as yet there has been little in the way of interventional study of this condition which are much needed. In this review we dissect existing clinical and experimental data to better characterise the manifestations of ACLF on the brain and allow for the development of targeted therapy as currently the plethora of existing interventions were designed to treat either the effects of cirrhosis or acute liver injury independently.

The liver protective effect of methylprednisolone on a new experimental acute-on-chronic liver failure model in rats

BACKGROUND

Acute-on-chronic liver failure is a severe, life-threatening entity and the comprehension of this disease is incomplete. Currently, a reasonable surgical model of acute-on-chronic liver failure is still lacking. The aim of this study was to establish a new model of acute-on-chronic liver failure in rats and to investigate the protective effects of methylprednisolone on this model.

METHODS

An obstructive jaundice model in rats was established. Two weeks later, the animals were subjected to a choledochoduodenostomy and a reduced-size hepatic ischaemia/reperfusion injury. Animals were randomly divided into a control group, a methylprednisolone injected via the tail vein group and a methylprednisolone injected via the portal vein group. The survival rates and serum levels of alanine transaminase, aspartate aminotransferase, total bilirubin, tumour necrosis factor alpha, and interferon gamma of the rats were measured and the pathological changes in liver tissues were observed.

RESULTS

The survival rate was significantly improved in the methylprednisolone treatment groups. Serum levels of the biochemical indexes were the lowest in the portal vein injection group. Liver tissues under microscopy presented severe pathological injury in the control group.

CONCLUSION

This model could be useful for further research into acute-on-chronic liver failure and methylprednisolone may be a potential therapeutic agent for this disease.

A zebrafish model of hyperammonemia

Hyperammonemia is the principal consequence of urea cycle defects and liver failure, and the exposure of the brain to elevated ammonia concentrations leads to a wide range of neuro-cognitive deficits, intellectual disabilities, coma and death. Current treatments focus almost exclusively on either reducing ammonia levels through the activation of alternative pathways for ammonia disposal or on liver transplantation. Ammonia is toxic to most fish and its pathophysiology appears to be similar to that in mammals. Since hyperammonemia can be induced in fish simply by immersing them in water with elevated concentration of ammonia, we sought to develop a zebrafish (Danio rerio) model of hyperammonemia. When exposed to 3mM ammonium acetate (NH4Ac), 50% of 4-day old (dpf) fish died within 3hours and 4mM NH4Ac was 100% lethal. We used 4dpf zebrafish exposed to 4mM NH4Ac to test whether the glutamine synthetase inhibitor methionine sulfoximine (MSO) and/or NMDA receptor antagonists MK-801, memantine and ketamine, which are known to protect the mammalian brain from hyperammonemia, prolong survival of hyperammonemic fish. MSO, MK-801, memantine and ketamine all prolonged the lives of the ammonia-treated fish. Treatment with the combination of MSO and an NMDA receptor antagonist was more effective than either drug alone. These results suggest that zebrafish can be used to screen for ammonia-neuroprotective agents. If successful, drugs that are discovered in this screen could complement current treatment approaches to improve the outcome of patients with hyperammonemia.

Carvacrol ameliorates thioacetamide-induced hepatotoxicity by abrogation of oxidative stress, inflammation, and apoptosis in liver of Wistar rats

The present study was designed to investigate the protective effects of carvacrol against thioacetamide (TAA)-induced oxidative stress, inflammation and apoptosis in liver of Wistar rats. In this study, rats were subjected to concomitant prophylactic oral pretreatment of carvacrol (25 and 50 mg kg(-1) body weight (b.w.)) against the hepatotoxicity induced by intraperitoneal administration of TAA (300 mg kg(-1) b.w.). Efficacy of carvacrol against the hepatotoxicity was evaluated in terms of biochemical estimation of antioxidant enzyme activities, histopathological changes, and expressions of inflammation and apoptosis. Carvacrol pretreatment prevented deteriorative effects induced by TAA through a protective mechanism in a dose-dependent manner that involved reduction of oxidative stress, inflammation and apoptosis. We found that the protective effect of carvacrol pretreatment is mediated by its inhibitory effect on nuclear factor kappa B activation, Bax and Bcl-2 expression, as well as by restoration of histopathological changes against TAA administration. We may suggest that carvacrol efficiently ameliorates liver injury caused by TAA.

Hepatoprotective effect of germanium-containing Spirulina in rats with d-galactosamine- and lipopolysaccharide-induced hepatitis

In the present study, the protective effects of dietary Spirulina (SP) and germanium-containing Spirulina (GeSP) were compared in rats with liver injury induced by an intraperitoneal injection of d-galactosamine and lipopolysaccharide (GalN/LPS). Wistar rats were fed one of the following diets: the basal diet (GalN/LPS-CON group; n 6), the basal diet supplemented with 5 % SP or GeSP (GalN/LPS-SP and GalN/LPS-GeSP group, respectively; n 7 each). After administering these diets for 7 d, each rat was intraperitoneally injected with GalN/LPS. Increases in plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were suppressed in the GalN/LPS-GeSP group (GalN/LPS-CON v. GalN/LPS-GeSP: ALT 1052 (sem 187) v. 509 (sem 88) IU/l and AST 2183 (sem 368) v. 1170 (sem 196) IU/l) following the injection of GalN/LPS. Plasma levels of interferon-γ (IFN-γ) and TNF-α in GeSP-fed rats were significantly lower when compared with those in the GalN/LPS-CON group (GalN/LPS-CON v. GalN/LPS-GeSP: IFN-γ 142·8 (sem 17·5) v. 66·8 (sem 9·7) pg/ml and TNF-α 72·3 (sem 15·4) v. 31·2 (sem 6·8) pg/ml). However, the decrease in these levels observed in the GalN/LPS-SP group was not as prominent as those observed in the GalN/LPS-GeSP group. Furthermore, the increase in liver catalase (CAT) and glutathione peroxidase (GPx) activities, as well as the level of oxidised glutathione (GSSG), was more suppressed in GeSP-fed rats (GalN/LPS-CON v. GalN/LPS-GeSP: CAT 457 (sem 47) v. 262 (sem 54) U/mg liver protein; GPx 1·30 (sem 0·11) v. 0·53 (sem 0·09) U/mg liver protein; GSSG 2·18 (sem 0·33) v. 1·31 (sem 0·24) mmol/kg liver) after the injection of GalN/LPS. These changes were more pronounced in the GalN/LPS-GeSP group than in the GalN/LPS-SP group. These results suggest that GeSP could afford a significant protective effect in the alleviation of GalN/LPS-induced hepatic damage. In addition, the results indicate that GeSP is more effective than SP.

Ethyl pyruvate protects against experimental acute-on-chronic liver failure in rats

AIM: To investigate the protective effects of ethyl pyruvate (EP) on acute-on-chronic liver failure (ACLF) in rats.

METHODS: An ACLF model was established in rats, and animals were randomly divided into normal, model and EP treatment groups. The rats in EP treatment group received EP (40 mg/kg) at 3 h, 6 h, 12 h and 24 h after induction of ACLF. Serum endotoxin, high mobility group box-1 (HMGB1), alanine transaminase (ALT), tumor necrosis factor-α (TNF-α), interferon-α (IFN-γ), interleukin (IL)-10 and IL-18 levels, changes of liver histology and HMGB1 expressions in liver tissues were detected at 48 h after induction of ACLF. The effects of EP on the survival of ACLF rats were also observed.

RESULTS: Serum levels of endotoxin (0.394 ± 0.066 EU/mL vs 0.086 ± 0.017 EU/mL, P < 0.001), HMGB1 (35.42 ± 10.86 μg/L vs 2.14 ± 0.27 μg/L, P < 0.001), ALT (8415.87 ± 3567.54 IU/L vs 38.64 ± 8.82 IU/L, P < 0.001), TNF-α (190.77 ± 12.34 ng/L vs 124.40 ± 4.12 ng/L, P < 0.001), IFN-γ (715.38 ± 86.03 ng/L vs 398.66 ± 32.91 ng/L, P < 0.001), IL-10 (6.85 ± 0.64 ng/L vs 3.49 ± 0.24 ng/L, P < 0.001) and IL-18 (85.19 ± 3.49 ng/L vs 55.38 ± 1.25 ng/L, P < 0.001) were significantly increased, and liver tissues presented severe pathological injury in the model group compared with the normal group. However, EP administration significantly improved hepatic histopathology and reduced the serum levels of endotoxin (0.155 ± 0.045 EU/mL vs 0.394 ± 0.066 EU/mL, P < 0.001) and inflammatory cytokines (11.13 ± 2.58 μg/L vs 35.42 ± 10.86 μg/L for HMGB1, 3512.86 ± 972.67 IU/L vs 8415.87 ± 3567.54 IU/L for ALT, 128.55 ± 5.76 ng/L vs 190.77 ± 12.34 ng/L for TNF-α, 438.16 ± 38.10 ng/L vs 715.38 ± 86.03 ng/L for IFN-γ, 3.55 ± 0.36 ng/L vs 6.85 ± 0.64 ng/L for IL-10, and 60.35 ± 1.63 ng/L vs 85.19 ± 3.49 ng/L for IL-18, respectively, P < 0.001), and the levels of HMGB1 in liver tissues regardless of treatment time after induction of ACLF. EP treatment at the four time points prolonged the median survival time of ACLF rats (60 h) to 162 h, 120 h, 102 h and 78 h, respectively (χ² = 41.17, P < 0.0001).

CONCLUSION: EP administration can protect against ACLF in rats, and is a potential and novel therapeutic agent for severe liver injury.

The effects of anesthetic regimen in 90% hepatectomy in rats

PURPOSE: To evaluate the influence of the anesthetic regimen on anesthetic recovery, survival, and blood glucose levels following a 90% partial hepatectomy in rats. METHODS: Thirty adult male Wistar rats were divided into two groups according to their anesthetic regimens: intraperitoneal ketamine and xylazine or inhaled isoflurane. In order to prevent hypoglycemia, glucose was administered intraperitoneally and glucose (20%) was added to the drinking water. RESULTS: Anesthetic recovery time was longer in the ketamine and xylazine group. The survival rate after 72 hours was lower (log rank=0.0001) in the ketamine and xylazine group (0.0%) than in the isoflurane group (26.7%). The blood glucose after six hours was lower (p=0.017) in the ketamine and xylazine group (63±31.7 mg/dL) than in the isoflurane group (98±21.2 mg/dL). The prolonged anesthesia recovery time associated with ketamine and xylazine decreased the survival rate and blood glucose levels after 90% hepatectomy. CONCLUSION: Isoflurane anesthesia reduced the recovery time and incidence of hypoglycemia and increased the survival rate in the early hours, providing a therapeutic window that is suitable for experimental studies.

A modified surgical model of fulminant hepatic failure in the rat

BACKGROUND

There is a need for better animal models of fulminant liver failure (FHF). Eguchi et al described an interesting surgical model of FHF in the rat. This model includes 68% partial hepatectomy, ischemia of 24% of the liver mass, and 8% of remnant liver left intact. In the original description by Eguchi et al, rats were administered subcutaneous glucose. However, the authors found that normothermic FHF rats with subcutaneous glucose died from deep hypoglycemia. In this report, we describe a modification of that model, and show that administration of intravenous glucose allows better survival and development of intracranial hypertension.

METHODS

We operated on FHF rats using the procedure described by Eguchi et al, kept them normothermic, and maintained normoglycemia by continuous intravenous glucose injection (glucose 10%, 1 mL/h). At 24 h, we monitored liver blood tests (n = 5), intracranial pressure (n = 5), clinical encephalopathy, and survival (n = 10), and compared them with sham and 68% hepatectomy rats.

RESULTS

The FHF rats developed acute cytolysis, cholestasis, and liver failure, as demonstrated by the liver blood tests. They experienced progressive encephalopathy and intracranial hypertension leading to death. Mean survival was 45.9 h. Of 10 FHF rats from the survival evaluation cohort, one survived 7 d. Laparotomy showed necrosis of lateral liver lobes and enlargement of omental lobes with a normal hepatic aspect, suggesting liver recovery.

CONCLUSIONS

This surgical rat model mimics the features of human FHF and seems interesting for further research into the pathophysiology and therapeutic management of the disease.

Sterically stable liposomes improve the therapeutic effect of hepatic stimulator substance on fulminant hepatic failure in rats

BACKGROUND AND AIMS

Few drugs have been confirmed to be effective for fulminant hepatic failure (FHF). The purpose of this study was to prepare sterically stable liposomes (SSL) encapsulating hepatic stimulator substance (HSS) and determine their therapeutic effect on FHF.

METHODS

HSS were encapsulated into SSL (HSS-SSL). FHF was induced in rats by thioacetamide (TAA) injection (400mg/kg, three times with a 24-h interval). The agents, including HSS-SSL, SSL, HSS, and sodium chloride (NS), were each injected intravenously 2h after the second and the third TAA injection.

RESULTS

Freshly prepared HSS-SSL had a mean size of 93.59nm and the average encapsulation efficiency was 37.20%. HSS encapsulated in SSL showed a longer half life and more potent target to injured livers than free HSS. Twenty-four hours after the third TAA-injection, the survival rate of HSS-SSL-treated rats (80%) was significantly higher than that of rats treated with NS (20%), SSL (25%), or HSS (50%). Histopathologic examination showed that there was the least necrosis and inflammation in the livers of HSS-SSL-treated rats. The incidence of stage 3 or 4 hepatic encephalopathy in HSS-SSL-treated rats was significantly lower than that in rats treated with other agents. The serum pro-inflammatory cytokine levels and hepatic lipid peroxidation levels were both markedly reduced, while hepatocyte proliferative rate was markedly increased after HSS-SSL treatment.

CONCLUSION

Encapsulation by SSL markedly improved the therapeutic effect of HSS on FHF in rats. Encapsulation by SSL may be an effective approach to enhance the therapeutic potency of drugs for FHF.

Development of a porcine model of post-hepatectomy liver failure

BACKGROUND

The aim of this study was to develop a porcine model of post-operative liver failure (POLF) that could accurately reproduce all the neurological and metabolic parameters of the corresponding clinical syndrome that may develop after extensive liver resections.

METHODS

In our model, we induced POLF by combining extended left hepatectomy and ischemia of the small liver remnant of 150 min duration. Subsequently, the remnant liver parenchyma was reperfused and the animals were closely monitored for 24 h.

MATERIALS

Twelve Landrace pigs (weight 25-30 kg) were randomly assigned in two groups; eight of them constituted the experimental group, in which POLF was induced (POLF group, n = 8), whereas the rest of them (n = 4) were included in the control group (sham laparotomy without establishment of POLF). RESULTS (MEANS ± SD): All POLF animals gradually developed neurological and biochemical signs of liver failure including, among many other parameters, elevated intracranial pressure (24.00 ± 4.69 versus 10.17 ± 0.75, P = 0.004) and ammonia levels (633.00 ± 252.21 versus 51.50 ± 9.49, P = 0.004) compared with controls. Histopathologic evaluation of the liver at the end of the experiment demonstrated diffuse coagulative necrosis and severe architectural distortion of the hepatic parenchyma in all POLF animals.

CONCLUSION

Our surgical technique creates a reproducible porcine model of POLF which can be used to study the pathophysiology and possible therapeutic interventions in this serious complication of extensive hepatectomies.

Is rat liver affected by non-alcoholic steatosis more susceptible to the acute toxic effect of thioacetamide?

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic condition of the liver in the western world. There is only little evidence about altered sensitivity of steatotic liver to acute toxic injury. The aim of this project was to test whether hepatic steatosis sensitizes rat liver to acute toxic injury induced by thioacetamide (TAA). Male Sprague-Dawley rats were fed ad libitum a standard pelleted diet (ST-1, 10% energy fat) and high-fat gelled diet (HFGD, 71% energy fat) for 6 weeks and then TAA was applied intraperitoneally in one dose of 100 mg/kg. Animals were sacrificed in 24-, 48- and 72-h interval after TAA administration. We assessed the serum biochemistry, the hepatic reduced glutathione, thiobarbituric acid reactive substances, cytokine concentration, the respiration of isolated liver mitochondria and histopathological samples (H+E, Sudan III, bromodeoxyuridine [BrdU] incorporation). Activities of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase and concentration of serum bilirubin were significantly higher in HFGD groups after application of TAA, compared to ST-1. There were no differences in activities of respiratory complexes I and II. Serum tumour necrosis factor alpha at 24 and 48 h, liver tissue interleukin-6 at 72 h and transforming growth factor β1 at 24 and 48 h were elevated in TAA-administrated rats fed with HFGD, but not ST-1. TAA-induced centrilobular necrosis and subsequent regenerative response of the liver were higher in HFGD-fed rats in comparison with ST-1. Liver affected by NAFLD, compared to non-steatotic liver, is more sensitive to toxic effect of TAA.

Effects of intestinal intervention on bacterial translocation in a rat model of acute liver failure in vivo

BACKGROUND/AIMS

The study aimed to confirm bacterial translocation (BT) in rats with acute liver failure (ALF), to explore the correlation between the concentration of lipopolysaccharides and Toll-like receptor 4 (TLR4) expression, and further, to evaluate the curative effects of lactulose and montmorillonite (smecta) in this setting.

METHODS

D-Galactosamine was injected into the abdominal cavity of rats to induce ALF. Escherichia coli JM109 labeled with enhanced green fluorescent protein was administered to track BT. Simultaneously, the rats were given lactulose or smecta. Blood samples were collected for measuring liver function, cytokines, endotoxins, and TLR4 expression. Representative tissue specimens from the liver, spleen, and mesenteric lymph nodes were aseptically harvested for bacterial identification by agarose gel electrophoresis, laser scanning confocal microscopy, and flow cytometry.

RESULTS

BT occurred in ALF, accompanied by impaired liver function with increased cytokines, endotoxins, and TLR4 expression. After the treatment with lactulose or smecta, all these parameters decreased, including the relative quantity of translocated bacteria while albumin increased. Furthermore, compared with the lactulose treatment group, the parameters in the smecta treatment group improved. Moreover, in the group in which smecta was given for prophylaxis, there was greater improvement than with treatment.

CONCLUSION

Intestinal intervention with lactulose or smecta can ameliorate BT; moreover, smecta has a better effect than lactulose, and its preventive effect was also better than its therapeutic effect.

Melatonin prevents the decreased activity of antioxidant enzymes and activates nuclear erythroid 2-related factor 2 signaling in an animal model of fulminant hepatic failure of viral origin

This work was undertaken to investigate whether treatment with melatonin prevents oxidative stress and changes in the expression and activity of factor erythroid 2-related factor 2 (Nrf2)-mediated antioxidant enzymes in an animal model of fulminant hepatic failure of viral origin. Rabbits were experimentally infected with 2 x 10(4) hemagglutination units of a rabbit hemorrhagic disease virus (RHDV) isolate and received melatonin at two concentrations of 10 mg/kg and 20 mg/kg at 0, 12 and 24 hr postinfection. Blood transaminases, blood lactate dehydrogenase, liver concentration of thiobarbituric reactive acid substances and the liver oxidized to reduced glutathione ratio significantly increased at 36 hr postinfection in infected animals. Significant decreases were found in the mRNA levels and in the liver activities of Mn-superoxide dismutase, glutathione peroxidase and glutathione-S-transferase in infected rabbits. These effects were prevented by melatonin administration in a concentration-dependent manner. Melatonin treatment was not accompanied by changes in protein levels of Kelch-like ECH-associating protein 1 (Keap1) but resulted in an increased protein expression of Nrf2 in the cytoplasm and the nucleus, which was confirmed by the results of Nrf2 immunostaining. Nuclear extracts from livers of melatonin-treated rats displayed an enhanced antioxidant responsive element (ARE)-binding activity of Nrf2. Our results suggest a potential hepatoprotective role of melatonin in fulminant hepatic failure, partially mediated through the abrogation of oxidative stress and the prevention of the decreased activity of antioxidant enzymes via the Nrf2 pathways.

A new experimental model for acute hepatic failure in rats

PURPOSE

To develop a reliable surgical model of acute hepatic failure and hyperammonemia in rats that avoids porto-systemic shunt and bile duct ligation, applicable to hepatic encephalopathy research.

METHODS

The pedicles of right lateral and caudate lobes were exposed and clamped. One hour later, the animal was reopened, clamps were released and anterior subtotal hepatectomy (resection of median and left lateral lobes) was performed, comprising 75% of liver removal. Four hours after hepatectomy, blood samples and liver tissues were collected from ALF and control groups.

RESULTS

Differences between ALF and control groups were significant for ALT, AST, total and direct bilirubin, sodium, potassium, alkaline phosphatasis, gamma-glutamyltransferase and most important, ammonia. Histologically, significant differences were noticed between groups.

CONCLUSION

The model is useful for the study of specific aspects of ALF and the development of new therapeutic approaches.

Signaling pathways involved in liver injury and regeneration in rabbit hemorrhagic disease, an animal model of virally-induced fulminant hepatic failure

Management of fulminant hepatic failure (FHF) continues to be one challenging problem, and experimental animal models resembling its clinical conditions are still needed. Rabbit hemorrhagic disease (RHD) fullfils many requirements of an animal model of FHF. This work investigated changes in MAPK, NF-kappaB, AP-1 and STAT pathways during RHD-induced liver injury. Rabbits were infected with 2 x 10(4) hemagglutination units of an RHD virus isolate. Apoptosis was documented by the presence of caspase-3 activity and substantial PARP proteolysis at 36 and 48 h postinfection (pi). Infection induced a marked and maintained expression of TNF-alpha from 12 h pi, while there was only a transitory increase in IL-6 expression. Expression of phosphorylated (p)-JNK, p-p38 and p-ERK1/2 was significantly elevated at 12 h pi. At 48 h pi p-JNK expression was maintained at a maximum level, while that of p-p38 returned to normality and there was no p-ERK1/2 expression. Activation of NF-kappaB and AP-1 and increased expression of VCAM-1 and COX-2 were observed. No significant changes were detected in activation of STAT1 and STAT3, while SOCS3 expression increased significantly. The current findings suggest that activation of JNK is an essential component in liver injury mediated by the RHD virus and that lack of activation of STAT3, probably mediated by SOCS3 over-expression, would contribute to the inhibition of the regenerative response. Data show the presence of molecular mechanisms contributing to liver damage and the lack of regeneration and they support the usefulness of this model to investigate novel therapeutical modalities in FHF.

Minocycline attenuates oxidative/nitrosative stress and cerebral complications of acute liver failure in rats

In the present study, the effects of minocycline on progression of encephalopathy and brain edema in rats with acute liver failure (ALF) resulting from hepatic devascularization were studied in relation to the antioxidant action of the drug. ALF rats were sacrificed at precoma and coma stages of encephalopathy along with their appropriate sham-operated controls. Minocycline-treated ALF rats were sacrificed in parallel with comatose vehicle-treated ALF controls. Microglial activation was assessed using CD11b/c (OX-42) immunohistochemistry. Nitrite/nitrate levels in plasma and brain were measured using the Griess reaction. Expression of nitric oxide synthase (NOS) isoforms and heme oxygenase-1 (HO-1) were measured using real-time quantitative PCR and Western blot analysis. Increased nitrite/nitrate levels were observed in the plasma of ALF rats at coma stage of encephalopathy compared to sham-operated controls. Increased expression of HO-1 mRNA and protein was observed in the frontal cortex of ALF rats at both precoma and coma stages of encephalopathy. Significant increases in expression of endothelial (eNOS) and inducible (iNOS) isoforms of NOS mRNA and protein occurred only at coma stages of encephalopathy accompanied by increased brain nitrite/nitrate concentrations. As expected, minocycline attenuated microglial activation as confirmed by decreased OX-42 immunoreactivity, normalized nitrite/nitrate levels in brain and significantly attenuated HO-1, eNOS and iNOS expression. These results indicate that the beneficial effect of minocycline on the neurological complications of ALF is mediated, at least in part, by reduction of oxidative/nitrosative stress.

Hypothermia attenuates oxidative/nitrosative stress, encephalopathy and brain edema in acute (ischemic) liver failure

Encephalopathy and brain edema are serious complications of acute liver failure (ALF). The precise pathophysiologic mechanisms responsible have not been fully elucidated but it has been suggested that oxidative/nitrosative stress is involved. In the present study we evaluated the role of oxidative/nitrosative stress in the pathogenesis of hepatic encephalopathy and brain edema in rats with ALF resulting from hepatic devascularization. We also studied the effect of hypothermia, a treatment previously shown to delay the progression of encephalopathy and the onset of brain edema, on ALF-induced oxidative stress. ALF rats were sacrificed at precoma and coma stages of encephalopathy along with their appropriate sham-operated controls. Hypothermic ALF rats were sacrificed in parallel with normothermic comatose ALF rats. Nitric oxide production in plasma and brain was assessed indirectly by measuring the level of its stable end products, nitrite/nitrate (NOx), using the Griess reagent. Expression of nitric oxide synthase (NOS) isoforms and heme oxygenase-1 (HO-1) were measured using real-time quantitative PCR, Western blot analysis and immunohistochemistry. Increased nitrite/nitrate levels were observed in the plasma and frontal cortex in ALF rats at coma stage of encephalopathy compared to sham-operated controls. Increased expression of HO-1 protein and mRNA was observed in the frontal cortex of ALF rats at both precoma and coma stages of encephalopathy. Significant increases in expression of endothelial and inducible NOS mRNA isoforms also occurred at precoma and coma stages of encephalopathy. Expression of the neuronal nitric oxide synthase isoform (nNOS) was not altered by ALF. Hypothermia normalized nitrite/nitrate levels in brain and significantly attenuated HO-1, eNOS and iNOS expression. These results suggest that, oxidative/nitrosative stress participates in the pathogenesis of brain edema and its complications in ALF and that the beneficial effect of hypothermia depends in part on its ability to inhibit oxidative/nitrosative stress-related mechanisms.

Iron chelation attenuates intracranial pressure and improves survival in a swine model of acute liver failure

Oxidative mechanisms have been implicated in the pathogenesis of brain edema in acute liver failure (ALF). The aim of this study was to test the hypothesis that inhibition of iron-catalyzed oxidative reactions through iron chelation using deferoxamine could attenuate brain edema in a swine model of ischemic ALF. Following ALF induction (end-to-side portacaval anastomosis and ligation of the hepatoduodenal ligament), 14 animals were randomized to a study group that received an intravenous infusion of 150 mg/kg deferoxamine (group DF; n = 7) or a control group (group C; n = 7). Six sham-operated animals were also assigned to a deferoxamine-treated group (n = 3) or a control group (n = 3). Hemodynamic, neurological, and hematological parameters were monitored postoperatively. All sham animals maintained normal hemodynamics and intracranial pressure. At 18 hours, group DF animals had higher mean arterial pressure (mean +/- standard deviation: 98.0 +/- 15.9 versus 69.9 +/- 15.8 mmHg, P < 0.004), lower intracranial pressure (18.1 +/- 8.6 versus 32.7 +/- 13.4 mmHg, P < 0.032), and higher cerebral perfusion pressure (76.4 +/- 16.4 versus 37.1 +/- 25.6 mmHg, P < 0.006) in comparison with group C. Similar differences were recorded up to the 24th postoperative hour, leading to a significant difference in animal survival (88% in group DF versus 17% in group C, P < 0.001). Furthermore, group DF exhibited an attenuated increase of serum malondialdehyde from the baseline (16% versus 74%, P < 0.05) and lower brain malondialdehyde concentrations (3.7 +/- 1.3 versus 5.7 +/- 2.0 microM/mg of protein, P < 0.05) in comparison with controls. In conclusion, deferoxamine delayed the development of intracranial hypertension and improved survival in pigs with ischemic ALF.

Single dose intravenous thioacetamide administration as a model of acute liver damage in rats

Thioacetamide (TAA) has been used extensively in the development of animal models of acute liver injury. Frequently, TAA is administered intraperitoneally to induce liver damage under anaesthesia. However, it is rarely administered by intravenous injection in conscious rats. The experiments in this study were designed to induce acute liver damage by single intravenous injection of TAA (0, 70 and 280 mg/kg) in unrestrained rats. Biochemical parameters and cytokines measured during the 60-h period following TAA administration, included white blood cells (WBC), haemoglobulin (Hb), platelet, aspartate transferase (GOT), alanine transferase (GPT), total bilirubin (TBIL), direct bilirubin (DBI), albumin, ammonia (NH3), r-glutamyl transpeptidase (r-GT), tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). Rats were sacrificed by decapitation 60 h after TAA administration and livers were removed immediately for pathology and immunohistochemical (IHC) examination. Another group of rats were sacrificed by decapitation 1, 6 and 24 h after TAA administration and livers were removed immediately for time course change of pathology and IHC examination. TAA significantly increased blood WBC, GOT, GPT, TBIL, DBIL, NH3, r-GT, TNF-alpha and IL-6 levels but decreased the blood Hb, platelet and albumin level. The levels of histopathological damage in the liver after intravenous TAA administration were also increased with a dose-dependent trend and more increased at 60 h after TAA administration. The levels of inducible nitric oxide synthase (iNOS) and nuclear factor-kappaB (NF-kappaB) detected by IHC in the liver after intravenous TAA administration were also increased with a dose-dependent trend and more increased at 1 h after TAA administration. Single intravenous TAA administration without anaesthesia is a restorable animal model which may be used to investigate acute liver damage.

Arterial ammonia and clinical risk factors for encephalopathy and intracranial hypertension in acute liver failure

High circulating ammonia concentrations are common in patients with acute liver failure (ALF) and are associated with hepatic encephalopathy (HE) and intracranial hypertension (ICH). Other risk factors are poorly characterized. We evaluated the relation of the admission arterial ammonia concentration and other clinical variables with the development of HE and ICH. Arterial ammonia was measured on admission to the intensive care unit in 257 patients; 165 had ALF and severe HE, and there were 3 control groups: acute hepatic dysfunction without severe HE (n = 50), chronic liver disease (n = 33), and elective surgery (n = 9). Variables associated with ICH and HE were investigated with regression analysis. Ammonia was higher in ALF patients than controls. An independent risk factor for the development of severe HE and ICH, a level greater than 100 mumol/L predicted the onset of severe HE with 70% accuracy. The model for end-stage liver disease (MELD) score was also independently predictive of HE, and its combination with ammonia increased specificity and accuracy. ICH developed in 55% of ALF patients with a level greater than 200 mumol/L, although this threshold failed to identify most cases. After admission, ammonia levels remained high in those developing ICH and fell in those who did not. Youth, a requirement for vasopressors, and renal replacement therapy were additional independent risk factors.

CONCLUSION

Ammonia is an independent risk factor for the development of both HE and ICH. Additional MELD scoring improved the prediction of HE. Factors other than ammonia also appear important in the pathogenesis of ICH. Ammonia measurements could form part of risk stratification for HE and ICH, identifying patients for ammonia-lowering therapies and invasive monitoring.

A surgical model of fulminant hepatic failure in rabbits

AIM

Animal models of fulminant hepatic failure (FHF) have been developed for characterization of disease progression and to evaluate the effectiveness of liver-assist devices, some by treatment with hepatotoxic drugs, viral hepatitis or surgical procedures. We have developed a model in the rabbit by combining resection of the three anterior lobes with ligation of the pedicle of the right lateral lobes, resulting in liver necrosis; the remnant quadrate lobes are left intact.

MATERIALS AND METHODS

Adult male New Zealand white rabbits (n=16) were used. Six animals were killed to measure the weight of the separate liver lobes. The others (n=10) underwent left neck central line placement to monitor continuous blood pressure and collect blood for laboratory analysis, and a burr hole on the right parietal bone to monitor the intracranial pressure (ICP). Blood laboratory analysis, clinical hepatic encephalopathy and ICP levels were measured in FHF animals (n=6). Animals (n=4) undergoing a sham operation served as controls.

RESULTS

All FHF animals died between 12 and 26 h after liver surgery from FHF characterized by a progressive increase in liver enzymes, ammonia, total bilirubin, coagulopathy, hepatic encephalopathy and intracranial hypertension. Histological features of the ischaemic lobes showed coagulative necrosis of hepatocytes with absence of nuclei and collapse of cell plates. Brain histology revealed hypoxic cell damage.

CONCLUSION

We have developed a simple, reproducible model of FHF in rabbits that has a number of features comparable with clinical FHF patients and is well suited for testing experimental bioartificial liver systems and investigating the pathogenesis of FHF.

Early growth response-1 contributes to galactosamine/lipopolysaccharide-induced acute liver injury in mice

Early growth response (Egr)-1 is a transcription factor that regulates genes involved in inflammation, innate and adaptive immunity, coagulation, and wound healing; however, little is known about the role of Egr-1 in acute liver injury. We tested the hypothesis that Egr-1 is involved in acute liver injury induced by galactosamine/lipopolysaccharide (GalN/LPS). GalN/LPS exposure biphasically increased hepatic egr-1 mRNA accumulation at 1 h and again at 4-5.5 h after treatment in wild-type mice. Within 4-5.5 h after GalN/LPS exposure, wild-type mice exhibited histological evidence of hepatocyte injury, cell death, and extensive areas of hemorrhage, as well as increased plasma alanine aminotransferase activities. In contrast, these parameters were largely attenuated in egr-1(-/-) mice. The initial expression of tumor necrosis factor-alpha, macrophage inflammatory protein-2, monocyte chemoattractant protein-1, and intercellular adhesion molecule-1 mRNA or protein was equivalent between genotypes at 1 h after GalN/LPS administration. However, at subsequent time points, hepatic expression of these genes was decreased in egr-1(-/-) compared with wild-type mice. In addition, neutrophil extravasation from hepatic sinusoids into the liver parenchyma was decreased in egr-1(-/-) compared with wild-type mice 4 h after GalN/LPS. Whereas caspase-3 activation and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive nuclei were detected in wild-type mice at 4 and 5.5 h after GalN/LPS administration, respectively, these markers of apoptosis were delayed in egr-1(-/-) mice. Delayed development of apoptosis was associated with an extension of survival by 1 h in egr-1(-/-) compared with wild-type mice. These data demonstrate that Egr-1 plays an important role in acceleration of hepatic inflammation, apoptosis, and subsequent mortality in GalN/LPS-induced acute liver injury.

N-acetyl-cysteine protects liver from apoptotic death in an animal model of fulminant hepatic failure

BACKGROUND

This work was undertaken to investigate whether treatment with N-acetyl-cysteine (NAC) prevents oxidative stress and inhibits the apoptotic pathways in an animal model of fulminant hepatic failure.

METHODS

Rabbits were experimentally infected with 2x10(4) hemagglutination units of a rabbit hemorrhagic disease virus isolate.

RESULTS

The spontaneous mortality rate of infected animals was 67% at 36 h post infection (pi) and 90% at 48 h pi. This percentage decreased significantly in animals receiving an i.p. injection of NAC (150 mg/kg body way/daily), for 7 days prior to infection. From 36 h pi marked increases were detected in blood levels of transaminases, lactate dehydrogenase, bilirubin and the oxidised/reduced glutathione ratio. All these effects were significantly prevented by NAC treatment. The Bax to Bcl-2 relative expression, the expression of FasL, cytochrome c and PARP-1, and the activity of caspase 3 were significantly increased at 36 and 48 h pi in infected animals. These changes were markedly reduced in animals treated with NAC, with the exception of FasL.

CONCLUSION

Our results suggest a potential hepatoprotective role of NAC in fulminant hepatic failure, mediated partially through the modulation of the intrinsic pathway of apoptosis.

Proteomic profiling of animal models mimicking skeletal muscle disorders

Over the last few decades of biomedical research, animal models of neuromuscular diseases have been widely used for determining pathological mechanisms and for testing new therapeutic strategies. With the emergence of high-throughput proteomics technology, the identification of novel protein factors involved in disease processes has been decisively improved. This review outlines the usefulness of the proteomic profiling of animal disease models for the discovery of new reliable biomarkers, for the optimization of diagnostic procedures and the development of new treatment options for skeletal muscle disorders. Since inbred animal strains show genetically much less interindividual differences as compared to human patients, considerably lower experimental repeats are capable of producing meaningful proteomic data. Thus, animal model proteomics can be conveniently employed for both studying basic mechanisms of molecular pathogenesis and the effects of drugs, genetic modifications or cell-based therapies on disease progression. Based on the results from comparative animal proteomics, a more informed decision on the design of clinical proteomics studies could be reached. Since no one animal model represents a perfect pathobiochemical replica of all of the symptoms seen in complex human disorders, the proteomic screening of novel animal models can also be employed for swift and enhanced protein biochemical phenotyping.

Major HGF-mediated regenerative pathways are similarly affected in human and canine cirrhosis

Background

The availability of non-rodent animal models for human cirrhosis is limited. We investigated whether privately-owned dogs (Canis familiaris) are potential model animals for liver disease focusing on regenerative pathways. Several forms of canine hepatitis were examined: Acute Hepatitis (AH), Chronic Hepatitis (CH), Lobular Dissecting Hepatitis (LDH, a specific form of micronodulair cirrhosis), and Cirrhosis (CIRR). Canine cirrhotic samples were compared to human liver samples from cirrhotic stages of alcoholic liver disease (hALC) and chronic hepatitis C infection (hHC).

Results

Canine specific mRNA expression of the regenerative hepatocyte growth factor (HGF) signaling pathway and relevant down-stream pathways were measured by semi-quantitative PCR and Western blot (STAT3, PKB, ERK1/2, and p38-MAPK). In all canine groups, levels of c-MET mRNA (proto-oncogenic receptor for HGF) were significantly decreased (p < 0.05). Surprisingly, ERK1/2 and p38-MAPK were increased in CH and LDH. In the human liver samples Western blotting indicated a high homology of down-stream pathways between different etiologies (hALC and hHC). Similarly activated pathways were found in CIRR, hALC, and hHC.

Conclusion

In canine hepatitis and cirrhosis the major regenerative downstream pathways were activated. Signaling pathways are similarly activated in human cirrhotic liver samples, irrespective of the differences in etiology in the human samples (alcohol abuse and HCV-infection). Therefore, canine hepatitis and cirrhosis could be an important clinical model to evaluate novel interventions prior to human clinical trials.