Classification, etiology, and considerations of outcome in acute liver failure

A retrospective autopsy study of histopathologic spectrum and etiologic trend of fulminant hepatic failure from north India

Background

Fulminant hepatic failure (FHF) is rapidly fatal and liver transplant is the treatment of choice. The condition is known for its heterogeneity of defining criteria, clinical presentation, histologic spectrum and etiologic factors. The etiology of FHF varies widely, some of which includes viral hepatitis, drug overdose and idiosyncratic drug reactions. The identification of the etiology of FHF is critically important, because it influences the management. A histopathological classification of FHF has not been reported earlier in the literature.

Methods

The current study was conducted retrospectively on 224 autopsies at a tertiary care hospital in India. In all of these cases the liver was examined grossly and microscopically. Clinical findings, serological data and immunohistochemical findings were correlated with the morphological subtypes and a consensus morphological classification was formulated.

Results

Young females, especially those in the reproductive age group were most susceptible to the disease. Hepatotropic viruses and drugs were the likely causes in most of the patients. Clinical presentation is important, as delayed onset of encephalopathy or the subacute FHFs lead to maximum mortality. After careful gross and microscopic examination the morphological findings of FHF were divided into four distinct categories. Histologic typing can sometimes be misleading if solely made on H & E slides without application of special stains.

Conclusion

Fulminant hepatic failure is a medical emergency, proper histological categorization can help in deciding the treatment modalities.

Comparison of the applicability of two prognostic scoring systems in patients with fulminant hepatic failure

BACKGROUND

Distinguishing those patients with fulminant hepatic failure (FHF) and who require transplantation from those FHF patients who will survive with receiving only intensive medical care remains problematic, and this distinction is important because of the chronic shortage of donor livers.

METHODS

To assess the applicability of two prognostic scoring systems, referred to as the London and Clichy criteria, we compared using both systems, at the time of admission, for 43 FHF patients (15 M/28 F; age: 3716 yrs). Acetaminophen (ACM) was the etiology for 16 patients, while the remaining 27 had other etiologies. All the patients received intensive care, and 18 (8 ACM/10 non-ACM) had investigational BAL support.

RESULTS

For the ACM toxicity, neither the London nor the Clichy criteria exhibited acceptable sensitivity (71 vs 86%, respectively), specificity (78 vs 56%, respectively), a positive predictive value (71 vs 60%, respectively), a negative predictive value (78 vs 83%, respectively) or predictive accuracy (75 vs 69%, respectively) to predict patient survival without transplantation. In contrast, applying the London and Clichy criteria to the FHF patients with non-ACM etiologies showed a sensitivity of 96 vs 80%, respectively, a specificity of 100 vs 100%, respectively, a positive predictive value of 100 vs 100%, respectively a negative predictive value of 67 vs 29%, respectively and a predictive accuracy of 96% vs 82%, respectively.

CONCLUSIONS

Overall, the London criteria more accurately predicted the need for transplantation, and neither the London criteria nor the Clichy prognostic criteria accurately predicted the outcome of those patients who suffered with FHF due to ACM. BAL support may have contributed to the survival of the patients with ACM toxicity and who didn't undergo transplantation, and this survival exceeded the predictions of both prognostic systems. Additional multicenter studies should be conducted to refine these prognostic scoring systems, and this will help physicians rapidly identify those FHF patients who can survive without undergoing liver transplantation.

Liver transplantation()

Orthotopic liver transplantation (OLT) involves the substitution of a diseased native liver with a normal liver (or part of one) taken from a deceased or living donor. Considered an experimental procedure through the 1980s, OLT is now regarded as the treatment of choice for a number of otherwise irreversible forms of acute and chronic liver disease.The first human liver transplantation was performed in the United States in 1963 by Prof. T.E. Starzl of the University of Colorado. The first OLT to be performed in Italy was done in 1982 by Prof. R. Cortesini. The procedure was successfully performed at the Policlinico Umberto I of the University of Rome (La Sapienza).The paper reports the indications for liver transplantation, donor selection and organ allocation in our experience, surgical technique, immunosuppression, complications and results of liver transplantation in our center.

Altered immune function of monocytes in different stages of patients with acute on chronic liver failure

The aim of this study was to investigate the characteristics of the immune function of monocytes in different stages of the patients with acute on chronic liver failure (ACLF). Human leucocyte antigen (HLA)-DR and Toll-like receptor 4 (TLR-4) expression on monocytes in early and late stages of acute on chronic liver failure were detected by flow cytometry. The secretion function of monocytes was measured by cytometric bead array. Compared with healthy controls, the levels of HLA-DR expression on monocytes in patients with chronic hepatitis B, liver cirrhosis and acute on chronic liver failure were gradually decreased, especially in the late stage of acute on chronic liver failure (P < 0.001). TLR-4 expression on monocytes in patients with liver cirrhosis and acute on chronic liver failure were higher than the healthy controls. The concentrations of interleukin (IL)-1beta, tumour necrosis factor (TNF)-alpha and IL-12p70 in early-stage ACLF were significantly higher compared with healthy controls and lower in late-stage ACLF (P < 0.01, 0.05). However, a significantly lower amount of IL-10 was found on monocytes in early-stage ACLF than that of late-stage ACLF and healthy controls (P < 0.01). Monocyte HLA-DR expression in patients who died was significantly lower compared with patients who survived in the early and late stages of ACLF (P < 0.01). The dynamic detection of HLA-DR expression or cytokines secreted from monocytes could contribute to the estimation of the status of the immune function of patients with acute on chronic liver failure.

Mechanisms of Acute Liver Failure

Acute liver failure is characterized by the sudden onset of liver failure in a patient without evidence of chronic liver disease. This definition is important, as it differentiates patients with acute liver failure from patients who suffer from liver failure owing to end-stage chronic liver disease.

Hepatitis A virus infection suppresses hepatitis C virus replication and may lead to clearance of HCV

BACKGROUND/AIMS

The significance of hepatitis A virus (HAV) super-infection in patients with chronic hepatitis C had been a matter of debate. While some studies suggested an incidence of fulminant hepatitis A of up to 35%, this could not be confirmed by others.

METHODS

We identified 17 anti-HCV-positive patients with acute hepatitis A from a cohort of 3170 anti-HCV-positive patients recruited at a single center over a period of 12 years.

RESULTS

Importantly, none of the anti-HCV-positive patients had a fulminant course of hepatitis A. HCV-RNA was detected by PCR in 84% of the anti-HCV-positive/anti-HAV-IgM-negative patients but only in 65% of anti-HCV-positive patients with acute hepatitis A (p=0.03), indicating suppression of HCV replication during hepatitis A. Previous HAV infection had no effect on HCV replication. After recovery from hepatitis A, an increased HCV replication could be demonstrated for 6 out of 9 patients with serial quantitative HCV-RNA values available while 2 patients remained HCV-RNA negative after clearance of HAV throughout follow-up of at least 2 years.

CONCLUSIONS

HAV super-infection is associated with decreased HCV-RNA replication which may lead to recovery from HCV in some individuals. Fulminant hepatitis A is not frequent in patients with chronic hepatitis C recruited at a tertiary referral center.

Mannan binding lectin and viral hepatitis

Mannan binding lectin (MBL) is a pattern recognition molecule of the innate immune system that binds to sugars on the surface of invading micro-organisms. Target binding, complement activation and other functions of MBL are dependent on the presence of multiple carbohydrate recognition domains. Several polymorphisms in the promoter and structural regions of MBL2 adversely affect the plasma concentration and oligomeric state of MBL. The possession of mutant alleles has been linked to disease outcome for a variety of bacterial and viral infections. Viral hepatitis is caused by unrelated viruses referred to as hepatitis virus A-E. The disease usually has both acute and chronic phases, the latter leading to cirrhosis and hepatocellular carcinoma. Hepatitis viruses B and C (HBV and HCV, respectively) are a significant cause of morbidity worldwide. HBV encodes envelope glycoproteins termed large, middle, and small that may exist in glycosylated or unglycosylated forms on the virion. An interaction between HBV glycoproteins and MBL has been demonstrated in vitro. Significant associations between MBL levels, determined by MBL2 haplotypes, and HBV persistence and disease progression have been described. HCV encodes two highly glycosylated envelope proteins, E1 and E2, which are potential targets for interaction with MBL. Mutant MBL2 haplotypes have been linked to disease progression and response to therapy in HCV infection. Here we summarise the effect of MBL2 polymorphisms on MBL function and how this may relate to disease outcome in HBV and HCV infection.

Acute liver failure: a review

Since publication of the first descriptions of acute liver failure (ALF) as a distinct clinical entity in the 1950's, the understanding of the pathophysiologic mechanisms involved and the management options have increased substantially. ALF still represents a major challenge for todays hepatologists, because it can rapidly lead to multiorgan failure and death that may be preventable with appropriate intervention. This article summarizes the basic patho-physiology underlying ALF, compares epidemiologic trends in the United States, the United Kingdom, and the Far East, and reviews prognostic markers and treatment options for ALF.

Safety and efficacy of lamivudine in patients with severe acute or fulminant hepatitis B, a multicenter experience

Acute hepatitis B progresses to liver failure with the need of liver transplantation in about 1% of cases. We treated patients with severe acute or fulminant hepatitis B with lamivudine in an attempt to prevent hepatitis B virus (HBV) reinfection after potential liver transplantation. Since September 2000, 17 patients with severe acute or fulminant HBV infection were treated with 100 or 150 mg lamivudine daily once we had evidence for a severe course as indicated by an INR >2.0. These were compared to a historic control from our unit and to external patients. Fourteen of the 17 patients (82.4%) survived with full recovery without liver transplantation. All these 14 individuals cleared HBsAg on lamivudine within less than 6 months. Twelve patients recovered quickly as indicated by a normalized prothrombin time within 1 week while two patients had a more prolonged course. None of the patients showed an adverse event. Three patients requiring transplantation despite lamivudine therapy had more advanced disease on admission, of whom one had additionally ingested paracetamol (acetaminophen) while the second was already HBV-DNA negative by polymerase chain reaction on admission. The lamivudine treated patients had significant higher frequency of survival without liver transplantation 82.4 vs 20% (4/20) in the historic control (P < 0.001). Similar data were derived from external centres using lamivudine (15/20, 75%). Lamivudine is safe in patients with severe acute or fulminant hepatitis B, leading to fast recovery with the potential to prevent liver failure and liver transplantation when administered early enough.

The role of histamine H1 receptor and H2 receptor in LPS-induced liver injury

To examine the role of histamine H1 and H2 receptors in the regulation of lipopolysaccharide (LPS)-induced liver injury, a combination of D-galactosamine and LPS (GalN/LPS) was administered to histamine H1 receptor knockout (H1-R KO) and H2 receptor knockout (H2-R KO) mice. The numbers of necrotic and apoptotic hepatocytes in the liver, as well as the levels of serum aspartate transaminase (AST) and alanine transaminase (ALT), were increased significantly by GalN/LPS treatment compared to the appropriate controls. Pretreatment with histamine ameliorated the GalN/LPS-induced necrotic and apoptotic changes in the hepatocytes and inhibited the elevation of serum AST and ALT levels. Histamine attenuated the GalN/LPS-induced increases in the levels of TNF-alpha, but augmented those of IL-10 both in the liver and serum. Histamine inhibited the GalN/LPS-induced caspase-3 activity in the liver. Furthermore, these effects of histamine were completely or partially attenuated in H2-R KO mice, but not in H1-R KO mice. Peritoneal macrophages from H2-R KO mice exhibited blunted changes in the effects of histamine on LPS-induced TNF-alpha and IL-10 production in vitro compared to the wild-type (WT) controls. In summary, the present findings suggest that the histamine H2-R-TNF-alpha and -IL-10 pathways play protective roles in endotoxin-induced hepatic injury.

New prognostic scoring model for liver transplantation in patients with non-acetaminophen-related fulminant hepatic failure

BACKGROUND

Many patients with fulminant hepatic failure die before receiving liver transplantation because of the difficulty of pinpointing the suitable timing for liver transplantation. The revised King's College criteria are useful for patients with acetaminophen-related fulminant hepatic failure; however, in those with non-acetaminophen-related fulminant hepatic failure, a new prognostic system that can accurately identify the suitable timing for liver transplantation is required.

METHODS

Using the first sample consisted of eighty patients with fulminant hepatic failure, we examined 2-week poor prognostic parameters at the time of diagnosis of fulminant hepatic failure (day 1) and on days 4, 8, and 15, respectively, and a 2-week prognostic scoring model was constructed. To confirm the accuracy of this model, validation was performed in the second sample consisting of 26 patients.

RESULTS

Cause of fulminant hepatic failure (hepatitis B virus or indeterminate), hepatic coma grade (III or IV), systemic inflammatory response syndrome (yes) and ratio of total to direct bilirubin (> 2.0) were associated with 2-week outcomes during days 1-15. Each of these four parameters was valued at +1. The 2-week survival rate in patients scoring <3 was > or = 80% in contrast to less than 30% in patients scoring > or = 3. When this scoring model was applied to the second sample, the sensitivity, specificity, and positive and negative predictive values were 87.5%, 90.0%, 93.3%, and 81.8%, respectively.

CONCLUSIONS

This scoring model may be useful for predicting 2-week outcomes and determining the suitable timing for liver transplantation in patients with non-acetaminophen-related fulminant hepatic failure.

Acetaminophen-induced acute liver failure: results of a United States multicenter, prospective study

Severe acetaminophen hepatotoxicity frequently leads to acute liver failure (ALF). We determined the incidence, risk factors, and outcomes of acetaminophen-induced ALF at 22 tertiary care centers in the United States. Detailed prospective data were gathered on 662 consecutive patients over a 6-year period fulfilling standard criteria for ALF (coagulopathy and encephalopathy), from which 275 (42%) were determined to result from acetaminophen liver injury. The annual percentage of acetaminophen-related ALF rose during the study from 28% in 1998 to 51% in 2003. Median dose ingested was 24 g (equivalent to 48 extra-strength tablets). Unintentional overdoses accounted for 131 (48%) cases, intentional (suicide attempts) 122 (44%), and 22 (8%) were of unknown intent. In the unintentional group, 38% took two or more acetaminophen preparations simultaneously, and 63% used narcotic-containing compounds. Eighty-one percent of unintentional patients reported taking acetaminophen and/or other analgesics for acute or chronic pain syndromes. Overall, 178 subjects (65%) survived, 74 (27%) died without transplantation, and 23 subjects (8%) underwent liver transplantation; 71% were alive at 3 weeks. Transplant-free survival rate and rate of liver transplantation were similar between intentional and unintentional groups. In conclusion, acetaminophen hepatotoxicity far exceeds other causes of acute liver failure in the United States. Susceptible patients have concomitant depression, chronic pain, alcohol or narcotic use, and/or take several preparations simultaneously. Education of patients, physicians, and pharmacies to limit high-risk use settings is recommended.

Fulminant drug-induced hepatic failure leading to death or liver transplantation in Sweden

OBJECTIVE

There are only a few data on the prevalence of drug-induced liver injury associated with fatal outcome. The aim of this study was to determine the nature and number of suspected adverse drug-induced liver disease associated with fatalities and/or liver transplantation since reporting of adverse drug reactions (ADRs) started in Sweden.

MATERIAL AND METHODS

All reports of suspected hepatic ADRs with fatal outcome received by the Swedish Adverse Drug Reactions Advisory Committee (SADRAC) from 1966 to 2002 were reviewed and causality assessed.

RESULTS

The SADRAC received 151 reports of suspected ADRs with fatal outcome from liver injury; 48 cases were either unlikely or excluded. Of the remaining 103 cases, 13 (13%) were highly probable, 48 (47%) probable and 42 (41%) possible. The median age of the 103 patients was 64 years (47-77 interquartile range (IQR)) and 59 (57%) were males. The majority of cases were classified as hepatocellular (75%), with only 15% cholestatic and 10% mixed. Halothane, paracetamol, flucloxacillin, sulfamethoxazole/trimethoprim and diclofenac were the most common drugs associated with fatal outcome. Seventeen patients underwent liver transplantation, most commonly because of paracetamol and disulfiram toxicity.

CONCLUSIONS

A wide range of suspected ADRs are associated with fatalities. Antibiotics and analgesics are associated with the greatest number of reports of deaths.

Outcome and prognostic markers in severe drug-induced liver disease

The combination of high aminotransferases (hepatocellular injury) and jaundice has been reported to lead to a mortality rate of 10% to 50% for different drugs, a phenomenon known as "Hy's rule." However, Hy's rule has never been validated, and limited data exist on predictors for outcome in hepatocellular and other forms of drug-induced liver disease. All reports of suspected hepatic adverse drug reactions received by the Swedish Adverse Drug Reactions Advisory Committee (1970-2004) were reviewed. Cases with bilirubin levels 2 or more times the upper limit of normal (ULN) were analyzed. A total of 784 cases were retrieved-409 with hepatocellular injury, 206 with cholestatic injury, and 169 with mixed liver injury. The mortality/transplantation rate was 9.2%, and bilirubin (median 18.7 x ULN [IQR 12.6-25]; range 4.5-42) was higher (P < .0001) in the deceased/transplant recipients compared with the surviving patients (median 5.5 x ULN [IQR 3.3-9.5]; range 2.0-38). A total of 7.8% with cholestatic and 2.4% with a mixed pattern died. The mortality rate in hepatocellular injury for different drugs varied from 40% (6 of 15) for halothane to 0% (0 of 32) for erythromycin, in total 12.7%. Using logistic regression analysis, age, aspartate aminotransferase (AST) and bilirubin were found to independently predict death or liver transplantation in the hepatocellular group, whereas among patients with cholestatic/mixed liver injury, bilirubin was the only independent predictor. In conclusion, hepatocellular jaundice has a high but variable mortality rate, depending on the drug involved. The AST and bilirubin levels are the most important predictors of death or liver transplantation.

Liver transplantation for viral hepatitis

Viral hepatitis is associated with two forms of liver failure that may require liver transplantation: fulminant hepatic failure associated with all forms of acute viral hepatitis and chronic liver failure as a result of chronic hepatitis B and C infection (or both). This review briefly discusses liver transplantation for fulminant hepatitis but focuses on transplantation for hepatitis B- and hepatitis C-associated cirrhosis.

Selective priming to Toll-like receptor 4 (TLR4), not TLR2, ligands by P. acnes involves up-regulation of MD-2 in mice

Lipopolysaccharide (LPS) triggers cytokine production through Toll-like receptor 4 (TLR4), which shares downstream signaling pathways with TLR2. We investigated the roles of TLR2 and TLR4 in Propionibacterium acnes (P. acnes)-primed, LPS-induced liver damage using selective TLR ligands. Stock LPS induced interleukin 8 in both TLR4- and TLR2-expressing human embryonic kidney (HEK) 293 cells. Purified LPS (TLR4 ligand) activated HEK/TLR4 cells, while peptidoglycan and lipoteichoic acid (TLR2 ligands) activated HEK/TLR2 cells, respectively. In mice, P. acnes priming resulted in increased liver messenger RNA (mRNA) and serum levels of tumor necrosis factor alpha, interleukin 12, and interferon gamma (IFN-gamma) by both stock LPS and purified LPS challenges compared with nonprimed controls. In contrast, P. acnes failed to sensitize to TLR2 ligands (peptidoglycan + lipoteichoic acid). In the liver, P. acnes-priming was associated with up-regulation of TLR4 and MD-2 proteins, and subsequent LPS challenge further increased MD-2 and CD14 mRNA levels. The lack of sensitization to TLR2 ligands by P. acnes correlated with no increase in hepatic TLR1 or TLR6 mRNA. In vitro, P. acnes pretreatment desensitized RAW macrophages to a secondary stimulation via both TLR2 and TLR4. However, IFN-gamma could selectively prevent desensitization to TLR4 but not to TLR2 ligands. Furthermore, P. acnes induced production of IFN-gamma in vivo as well as in isolated splenocytes. In vitro, P. acnes-primed Hepa 1-6 hepatocytes but not RAW macrophages produced increased MD-2 and CD14 mRNA levels after an LPS challenge. In conclusion, P. acnes priming to selective TLR4-mediated liver injury is associated with up-regulation of TLR4 and MD-2 and is likely to involve IFN-gamma and prevent TLR4 desensitization by P. acnes.

Hepatitis B virus: prevalence of precore/core promoter mutants in different clinical categories of Indian patients

To determine the association of precore (Pre-C)/basal core promoter (BCP) mutants with clinical outcome of hepatitis B in Western India, 192 hepatitis B virus (HBV) infected individuals were investigated. HBV-DNA PCR positivity among asymptomatic hepatitis B surface antigen (HBsAg) positive carriers (61/100) was lower (P < 0.0001) than chronic hepatitis B (CHB), acute (P = 0.0001), and fulminant hepatitis B patients (P = 0.047). Pre-C status was based on restriction fragment length polymorphism (RFLP, n = 153) and sequencing (n = 118). Prevalence of Pre-C mutants was higher among carriers (23/61) than CHB (10/62, P = 0.0071) or acute (3/22; P = 0.037) patients. Children from carrier and CHB categories showed significantly higher circulation of Pre-C-wild than mutant HBV. Clinical manifestations were independent of BCP mutations (1762/64-T/A). Hepatitis B e antigen (HBeAg) negative CHB patients [62.5% (15/24)] were circulating wild HBV. Higher HBV-DNA levels were associated with chronic hepatitis and HBeAg positivity, whilst Pre-C mutant positives had lower levels. BCP mutations did not affect HBV-DNA levels. Multivariate regression analysis identified HBeAg (OR = 4.3) and Pre-C mutants (OR = 3.1) to be associated with chronic hepatitis and carriers respectively. In a separate sub-set analysis (n = 59), HBV-DNA level was identified as the only variable. In conclusion, chronic or fulminant hepatitis B was not associated with Pre-C or BCP mutants and switching over to Pre-C mutant was beneficial for the infected individual in maintaining disease free status for extended periods.

Nuclear factor kappa B decoy oligodeoxynucleotides prevent endotoxin-induced fatal liver failure in a murine model

Endotoxin syndrome is a systemic inflammatory response mediated by inflammatory cytokines. Nuclear factor kappa B (NF-kappa B) is the dominant regulator of the production of these cytokines by inflammatory cells. The aim of this study was to assess the efficacy of in vivo transfer of synthetic double-stranded oligodeoxynucleotides (ODN) with high affinity against NF-kappa B (NF-kappa B/decoy/ODN) as a therapeutic strategy for treating endotoxin-induced fatal liver injury. Liver injury was induced by administration of lipopolysaccharide (LPS) to Propionibacterium acnes-primed BALB/C mice. NF-kappa B/decoy/ODN was transferred into the portal vein using a fusigenic liposome with hemagglutinating virus of Japan. NF-kappa B/decoy/ODN was preferentially transferred to Kupffer cells, and activation of NF-kappa B after the LPS challenge was suppressed, leading to decreased inflammatory cytokine production. As a result, the massive necrosis and hepatocyte apoptosis observed in the control mice was dramatically attenuated and the survival rate improved. In conclusion, NF-kappa B/decoy/ODN transfer in vivo effectively suppressed endotoxin-induced fatal liver injury in mice.

[Fulminant hepatic failure and liver transplantation. Experience of the Hospital Virgen de la Arrixaca]

INTRODUCTION

Medical treatment for fulminat hepatic failure seeks spontaneous recovery of the liver function, but the results are very discouraging (50-80% mortality). Liver transplantation is an option in patients with a poor evolution despite medical treatment, with survival rates of > 50%. The ideal moment for performing the transplant is controversial, as it should not be done too soon, when the liver disease is still reversible, or tool late, when the patient is in an irreversible clinical situation.

PATIENTS AND METHOD

A retrospective review was made of the clinical histories of 34 patients admitted to our hospital with a diagnosis of fulminant hepatic failure, of whom 26 underwent transplantation. The most frequent cause was viral, with 10 cases (38%); no aetiology at all could be established in 11 cases (42%). Thirteen patients had preoperative complications, the most frequent being renal insufficiency. As for degree of ABO/DR compatibility, 13 cases were identical (40%), 17 compatible (51%) and the other 3 incompatible (9%).

RESULTS

Thirty-three transplants were performed in 26 patients: 4 were retransplants due to chronic rejection, 2 for primary graft failure and 1 for hyperacute rejection. The overall mortality rate was 46% (12 patients), the most frequent cause of death being infection (50%). The overall actuarial survival rate was 68% at 1 year, 63% at 3 years and 59% at 5 years. The factors of poor prognosis were renal and respiratory insufficiency, a grade D electroencephalogram, and encephalopathy grades III and IV, the latter being the only prognostic factor identified in the multivariate analysis. The prognostic factors for mortality were a grade D electroencephalogram, encephalopathy grades III and IV and respiratory insufficiency, the latter being the only prognostic factor identified in the multivariate analysis.

CONCLUSIONS

The achievement of good results with the use of transplantation in the management of fulminant hepatic failure depends on an optimum selection of transplant candidates, which means identifying them early, i.e. early indication for transplant, reduction in mean waiting time and exclusion of factors of poor prognosis.

Fulminant liver disease

Fulminant liver disease, acute liver failure (ALF), is one of the most intriguing and challenging conditions in the entire field of internal medicine. ALF is defined as the onset of hepatic encephalopathy and coagulopathy in patients with no known underlying liver disease within 8 to 26 weeks of onset of illness. Many cases develop within a few days, dramatically transforming an otherwise healthy individual to a patient with a high risk for developing multi-organ failure and death.

Troglitazone-induced liver failure: a case study

BACKGROUND

Troglitazone was removed from the U.S. market because its use was associated with an increased risk of liver failure. We evaluated the clinical features of all cases reported to the Food and Drug Administration and estimated the duration and magnitude of the risk of liver failure associated with continued use of the drug.

METHODS

Data from cases of liver failure associated with troglitazone use were abstracted and analyzed. The extent of troglitazone use was determined from national marketing data, and the duration of use was estimated with data from a large, multistate, health care company. Survival analysis was performed to estimate monthly incidence rates and the cumulative risk of liver failure.

RESULTS

Ninety-four cases of liver failure (89 acute, 5 chronic) were reported. Of the acute cases, 58 (67%) were women and only 11 (13%) recovered without liver transplantation. Progression from normal hepatic functioning to irreversible liver injury occurred within 1 month in 19 patients who were indistinguishable clinically from the 70 patients who had an unknown time course to irreversibility, except for the post hoc observation that prior cholecystectomy was less common in those with rapid onset. The incidence of liver failure was elevated from the first through at least the 26th month of troglitazone use. Accounting for case underreporting, the number needed to harm from troglitazone use was between 600 to 1500 patients at 26 months.

CONCLUSION

The progression to irreversible liver injury probably occurred within a 1-month interval in most patients, casting doubt on the value of monthly monitoring of serum aminotransferase levels as a means of preventing troglitazone-induced acute liver failure. The cumulative risk of hepatic failure increased with continued use.

Stem cell factor attenuates liver damage in a murine model of acetaminophen-induced hepatic injury

Acute liver injury is a common cause of intensive care unit visits. In these studies, we used a murine model of acetaminophen poisoning to examine the role of stem cell factor (SCF) on liver damage. In the initial studies, we identified that the liver produces relatively high constitutive levels of SCF. Upon administration of acetaminophen, the levels of SCF fell dramatically, correlating to damage within the liver. When the liver was allowed to regenerate, the levels of SCF again correlated with the liver regeneration. We next treated mice with anti-SCF before sublethal doses of acetaminophen and significantly increased lethality in anti-SCF-treated animals. When exogenous SCF was given to mice, the lethality was significantly reduced compared with the control acetaminophen-treated animals and the damage within the liver tissue was attenuated. The administration of rSCF reduced the level of steady-state mRNA for cytochrome P450 cyp2E1 enzyme both in vitro and in vivo. These data suggest that SCF functions as an important factor that protects livers from acute damage.

Etiology and management of fulminant hepatic failure

Fulminant hepatic failure (FHF) remains a rare but devastating disease. Viruses and drug-induced hepatotoxicity are the most common causes of the syndrome, but the relevance of each differs depending on the geographic area. In a large proportion of patients no cause for FHF can be identified. Good intensive care is critical for patient survival. Orthotopic liver transplantation (OLT) remains a definitive therapeutic option. Prognostic indices have helped to optimize patient selection and timing for performance of OLT. However, the accuracy of these prognostic indices decreases when they are applied to different populations, probably because of regional differences in etiology and peculiar native host factors. More accurate prognostic criteria and new therapeutic alternatives to OLT are required.

Incidence of idiopathic acute liver failure and hospitalized liver injury in patients treated with troglitazone

OBJECTIVE

Troglitazone, a thiazolidinedione antidiabetic agent, was withdrawn from the U.S. market in March, 2000, after 94 cases of acute liver failure (ALF) were reported with its use. Based on a literature review, the estimated background rate of hospitalization for idiopathic acute liver injury is 22 per million person-years and for idiopathic ALF, less than 1 per million person-years. This study was conducted to estimate the incidence rates of hospitalized idiopathic acute liver injury and ALF among troglitazone-treated patients.

METHODS

An observational retrospective inception cohort of patients treated with troglitazone was assembled using claims data from a large multistate health care organization. Patients with at least 90 days of health plan enrollment before their first troglitazone prescription between April, 1997 and December, 1998 were enrolled. Hospitalized cases of potential troglitazone-induced acute liver injury or ALF were identified from claims data based on International Classification of Diseases, 9th Revision, coding. Primary medical records were reviewed for case validation, and incidence rates of acute liver injury were calculated using person-years of troglitazone exposure as the denominator.

RESULTS

A total of 7568 patients contributed 4020 person-years of troglitazone exposure. Of these, five were hospitalized with acute liver injury attributed to the drug and not explained by other causes. Incidence rates (95% CI) per million person-years of acute idiopathic liver injury were as follows: hospitalization (n = 5), 1244 (404, 2900); hospitalized jaundice (n = 4), 995 (271, 2546); and ALF (n = 1), 240 (6.3, 1385).

CONCLUSIONS

Troglitazone use was associated with a marked increase in risk of hospitalized acute idiopathic liver injury and ALF.

Fulminant hepatic failure: outcome after listing for highly urgent liver transplantation-12 years experience in the nordic countries

Fulminant hepatic failure is a common indication for liver transplantation. Outcomes of patients listed for a highly urgent liver transplantation have been studied, with special emphasis on etiology of the liver disease, clinical condition, and ABO blood type. Data have been collected from the Nordic Liver Transplantation Registry. All Nordic patients listed for a highly urgent primary liver transplantation during a 12-year period have been included. Of the 315 patients listed for a highly urgent liver transplantation, 229 (73%) received a first liver allograft, 50 patients (16%) died without transplantation, and 36 patients (11%) were permanently withdrawn and survived. In 43% of the patients, no definite etiology of the liver failure could be established. Paracetamol intoxication was the most frequent specific indication for listing. Patients with blood type A had no significant shorter waiting time (3.8 v 6.6 days; P =.1) but a higher rate of transplantation (82% v 66%, P =.006) as compared with blood type O patients. In a multivariate analysis, paracetamol intoxication remained the single independent predictor of an outcome without transplantation. In conclusion, a high transplantation rate was observed among patients listed for a highly urgent liver transplantation because of fulminant hepatic failure. Blood type O patients had a lower chance of receiving a liver allograft. Patients with paracetamol intoxication had both a higher mortality without transplantation and a higher withdrawal rate attributable to improved condition.

Mortality risk factors of a pediatric population with fulminant hepatic failure undergoing orthotopic liver transplantation in a pediatric intensive care unit

OBJECTIVES: To determine risk factors of mortality in the preoperative, perioperative, and immediate postoperative period of a pediatric population that has undergone orthotopic liver transplantation for fulminant hepatic failure in a pediatric intensive care unit. DESIGN: Retrospective review of medical records. SETTING: A pediatric intensive care unit in a children's hospital. PATIENTS: Sixty patients with fulminant hepatic failure who fulfilled King's College criteria for liver transplantation. INTERVENTION: Orthotopic liver transplantation was performed according to standard techniques. Before transplantation, patients were admitted to a pediatric intensive care unit when intensive care was required, and patients were always admitted to a pediatric intensive care unit after the operation. Measurements: A total of 20 variables were studied via univariate and multivariate analysis; statistical significance was accepted when p </=.05. MAIN RESULTS: A total of 70 orthotopic liver transplantations were performed in 60 children (mean age, 64.11 +/- 40.97 months; range, 11 months to 14 yrs) for fulminant hepatic failure. Fulminant hepatic failure was caused by hepatitis A virus in 60% of cases, and non-A non-B non-C hepatitis was responsible in 40% of cases. Univariate analysis showed that the complications of infectious, hemodynamic, renal, and gastrointestinal bleeding are significant variables. Posttransplant respiratory support was also a significant variable. When the same variables were calculated with a multivariate analysis, no significant results were obtained. Multivariate analysis showed that mortality risk factors in this population were: etiology of liver failure (p <.002), liver size (p <.014), ischemia time (p <.041), ventilatory support before transplantation (p <.048), neurologic complications after orthotopic liver transplantation (p <.003), and acute rejection (p <.021). CONCLUSIONS: Hepatitis A virus is the major cause of fulminant liver failure in Argentina, but non-A non-B non-C hepatitis is an independent risk factor of mortality. Reduced-size graft, longer ischemia time, ventilatory support before orthotopic liver transplantation, neurologic complications, and acute rejection after transplantation are independent predictive factors of mortality. Better sanitary conditions and universal immunization for hepatitis A virus should reduce hepatitis A virus and hepatitis A virus-induced fulminant hepatic failure.

Inappropriate pemoline therapy leading to acute liver failure and liver transplantation

A 36-year-old female, presenting with jaundice, developed acute liver failure requiring orthotopic liver transplantation. On admission, none of the known causative factors for acute hepatitis, including use of drugs, were found to be present. Several days after hospitalization, the patient admitted taking therapy prescribed by a "non-traditional" physician, that she had been using for several years due to overweight and which had recently been modified with the introduction of pemoline. A considerable body of evidence exists in the medical literature showing that pemoline, which is a central nervous system stimulant, has variable hepatotoxic effects, ranging from a mild transient increase of serum transaminases to liver failure, including some lethal cases.

Single vs. dual vessel porcine extracorporeal liver perfusion

BACKGROUND

The use of porcine extracorporeal liver perfusion (PECLP) to provide temporary hepatic support for patients in fulminant hepatic failure has been limited by the fact that individual perfusions can be sustained for only a few hours. Inadequate liver function and/or hemodynamic instability are the major contributing factors for early interruption of PECLP. Recent reports suggest that the choice of single (portal vein only) vs dual (portal vein and hepatic artery) vessel perfusion may influence the duration of perfusion. We hypothesize that PECLP with single vessel perfusion (SVP) is associated with worse liver function and greater hemodynamic instability than PECLP with dual vessel perfusion (DVP).

MATERIALS AND METHODS

To eliminate the potentially confounding influences of liver failure and xenograft rejection, liver isografts procured from White-Landrace pig donors were perfused by either SVP or DVP via an extracorporeal circuit established with normal White-Landrace pig recipients. The function of perfused livers was evaluated by measuring production of bile and Factors V and VIII, clearance of ammonia and lactate, and extraction of O(2) at baseline and at 0, 1, 3, 6, 12, and 24 h after initiation of PECLP. The impact of PECLP on recipient hemodynamic status was assessed by monitoring BP, heart rate, urine output, O(2) saturation, etc. Among other parameters evaluated were serum albumin and total protein and hepatic release of IL-1beta and nitric oxide to assess their possible contributions to hemodynamic instability.

RESULTS

DVP and SVP livers cleared ammonia and lactate similarly. Both approaches were associated with progressive hypoalbuminemia and hypoproteinemia. DVP livers produced more bile and Factor V and were associated with less recipient hypotension and IL-1beta and NO release than SVP livers.

CONCLUSIONS

Livers with DVP function better than livers with SVP. The duration of PECLP can be limited by recipient hypotension, although this complication is less severe with DVP than with SVP.

Management of paracetamol overdose: current controversies

Paracetamol (acetaminophen) is one of the most frequently used analgesics, and is the most commonly used substance in self-poisoning in the US and UK. Paracetamol toxicity is manifested primarily in the liver. Treatment with N-acetyl-cysteine (NAC), if started within 10 hours from ingestion, can prevent hepatic damage in most cases. Pharmacokinetic data relating plasma paracetamol concentration to time after ingestion have been used to generate a 'probable hepatoxicity line' to predict which cases of paracetamol overdose will result in hepatotoxicity and should be treated with NAC. However, later studies use a 25% lower line as their 'possible hepatotoxicity line'. Although adopting the original line may save considerable resources, further studies are needed to determine whether such an approach is safe. On the basis of the metabolism of paracetamol, several risk factors for paracetamol toxicity have been proposed. These risk factors include long term alcohol (ethanol) ingestion, fasting and treatment with drugs that induce the cytochrome P450 2E1 enzyme system. Although some studies have suggested that these risk factors may be associated with worse prognosis, the data are inconclusive. However, until further evidence is available, we suggest that the lower line should be used when risk factors are present. In Canada and the UK, the intravenous regimen for NAC is used almost exclusively; in the US, an oral regimen is used. Both regimens have been shown to be effective. There is no large scale study with direct comparison between these 2 therapeutic protocols and controversy still exists as to which regimen is superior. During the last few years there has been an increase in the number of reports of liver failure associated with prolonged paracetamol administration for therapeutic reasons. The true incidence of this phenomenon is not known. We suggest testing liver enzyme levels if a child has received more than 75 mg/kg/day of paracetamol for more than 24 hours during febrile illness, and to treat with NAC when transaminase levels are elevated. Paracetamol overdose during pregnancy should be treated with either oral or intravenous NAC according to the regular protocols in order to prevent maternal, and potentially fetal, toxicity. Unless severe maternal toxicity develops, paracetamol overdose does not appear to increase the risk for adverse pregnancy outcome.

Graft function and survival depend primarily on host factors in compromised recipient models of orthotopic liver transplantation in the rat

BACKGROUND

Experimental models of liver transplantation use normal recipients, although most patients undergoing liver transplantation suffer from acute or chronic liver failure. This study was designed to analyze the outcome of orthotopic liver transplantation in compromised rat hosts.

METHODS

Recipient animals were either rats with D-galactosamine-induced acute or rats with chronic liver failure secondary to common bile duct ligation. Liver damage was evaluated by monitoring enzymes, bilirubin, ammonia levels, prothrombin, thrombin time, and cytokines. In vivo function of hepatocytes and sinusoidal endothelial cells were evaluated by indocyanine green and hyaluronic acid uptake. Transplantation was performed in normal, acute, and chronic liver failure rats at different time points using either freshly harvested or cold-preserved syngeneic livers.

RESULTS

Survival with fresh grafts decreased significantly when transplants were performed 48 hr after the induction of acute liver failure. No rats with acute liver failure survived transplantation with grafts stored for 12 or 24 hr although in chronic failure survival was more 80%. Survival of acute liver failure rats receiving 6 hr preserved grafts was 16.6% compared with 83.3% observed with fresh grafts transplanted at the same time point after D-galactosamine injection. Elevated tumor necrosis factor-alpha and interleukin-1beta levels as well as impaired sinusoidal endothelial cell function were detected in acute liver failure rats with 6 h preserved grafts.

CONCLUSION

These results suggest that preoperative status and different host factors have a significant effect on outcome and graft function after liver transplantation in rats.

Extracorporeal liver perfusion using human and pig livers for acute liver failure

BACKGROUND

Patients with fulminant hepatic failure (FHF) often die awaiting liver transplantation. Extracorporeal liver perfusion (ECLP) has been proposed as a method of "bridging" such patients to transplantation. We report the largest experience to date of ECLP using human and porcine livers in patients with acute liver failure.

METHODS

Patients with FHF unlikely to survive without liver transplantation were identified. ECLP was performed with human or porcine livers. Patients underwent continuous perfusion until liver transplantation or withdrawal of support. Two perfusion circuits were used: direct perfusion of patient blood through the extracorporeal liver and indirect perfusion with a plasma filter between the patient and the liver.

FINDINGS

Fourteen patients were treated with 16 livers in 18 perfusion circuits. Nine patients were successfully "bridged" to transplantation. ECLP stabilized intracranial pressure (ICP) and cerebral perfusion pressure (CPP). Arterial ammonia levels fell from a median of 146 to 83 micromol/liter within 12 hr and this reduction was maintained at least 48 hr. Pig and human ECLP lowered ammonia levels equally. Serum bilirubin levels also fell from a median of 385 to 198 micromol/liter over the first 12 hr but the response was not sustained as well with porcine livers. There was no immunological benefit to using the the filtered perfusion circuit.

INTERPRETATION

These data demonstrate that ECLP is safe and can provide metabolic support for comatose patients with fulminant hepatic failure for up to 5 days. While labor and resource intensive, this technology is available to centers caring for patients with acute liver failure and deserves wider evaluation and application.

Life-supporting human complement regulator decay accelerating factor transgenic pig liver xenograft maintains the metabolic function and coagulation in the nonhuman primate for up to 8 days

BACKGROUND

It is not known whether the pig liver is capable of functioning efficiently when transplanted into a primate, neither is there experience in transplanting a liver from a transgenic pigs expressing the human complement regulator human complement regulator decay accelerating factor (h-DAF) into a baboon. The objective of this study was to determine whether the porcine liver would support the metabolic functions of non-human primates and to establish the effect of hDAF expression in the prevention of hyperacute rejection of porcine livers transplanted into primates.

METHODS

Five orthotopic liver xenotransplants from pig to baboon were carried out: three from unmodified pigs and two using livers from h-DAF transgenic pigs.

FINDINGS

The three control animals transplanted with livers from unmodified pigs survived for less than 12 hr. Baboons transplanted with livers from h-DAF transgenic pigs survived for 4 and 8 days. Hyperacute rejection was not detected in the baboons transplanted with hDAF transgenic pig livers; however, it was demonstrated in the three transplants from unmodified pigs. Baboons transplanted with livers from h-DAF transgenic pigs were extubated at postoperative day 1 and were awake and able to eat and drink. In the recipients of hDAF transgenic pig livers the clotting parameters reached nearly normal levels at day 2 after transplantation and remained normal up to the end of the experiments. In these hDAF liver recipients, porcine fibrinogen was first detected in the baboon plasma 2 hr postreperfusion, and was present up to the end of the experiments. One animal was euthanized at day 8 after development of sepsis and coagulopathy, the other animal arrested at day 4, after an episode of vomiting and aspiration. The postmortem examination of the hDAF transgenic liver xenografts did not demonstrate rejection.

INTERPRETATION

The livers from h-DAF transgenic pigs did not undergo hyperacute rejection after orthotopic xenotransplantation in baboons. When HAR is abrogated, the porcine liver maintains sufficient coagulation and protein levels in the baboon up to 8 days after OLT.

Hepatitis A

Hepatitis A remains an important cause of community-acquired hepatitis in the United States and in the world. In recent years, improvements in personal hygiene and environmental sanitation have led to declines in overall hepatitis A infection rates in developed countries, although sporadic outbreaks still occur with similar rates of hospitalization and loss of work. Therapy remains supportive and prevention holds the key to elimination of widespread infection. Acute infection can be prevented or attenuated with IG or with inactivated, highly immunogenic vaccines. Elderly persons and those with advanced liver disease are at higher risk of the consequences of acute HAV, and they represent target populations for immediate vaccination. Challenges for the future include strategies for broad-based population vaccination, including cost-effective approaches.

Acute hepatic failure: a Western perspective

Acute hepatic failure (AHF) is an uncommon, devastating syndrome, which results in death or the need for liver transplantation in more than 50% of cases. While AHF has numerous causes, most cases are due to viral hepatitis and drug toxicity or idiosyncratic reactions. A significant group with indeterminate causation remains, despite careful investigation. In many of these cases a viral aetiology is suspected, although yet not proven. Major differences exist in the aetiology of AHF between the West and Eastern countries. A wider range of aetiologies exists in the West. Common causes include acetaminophen toxicity and idiosyncratic drug reactions, while viral hepatitis is less frequent. Hepatitis E infection is rarely seen in Western countries in contrast to its high prevalence in the East. The mainstay of AHF management is supportive care in an intensive care unit. Liver transplantation is now the standard of care in many Western liver units for individuals who have a less than 20% probability of survival. Lack of availability of donor livers at short notice remains a significant problem. Methods of liver support used while waiting for a donor liver or for the native liver to regenerate include bioartificial livers, extracorporeal liver-assist devices, extracorporeal whole organ perfusion (human and transgenic pig) and hepatocyte transplantation. The effectiveness of these methods remains unproven and awaits controlled clinical trials. Both transplantation and liver-support methods require specialized units and expensive and complicated equipment. Further research is necessary to identify modalities of therapy that would be effective as well as widely accessible.

Liver transplantation. American Association for the Study of Liver Diseases

Liver transplantation has revolutionized the care of patients with end-stage liver disease. Liver transplantation is indicated for acute or chronic liver failure from any cause. Because there are no randomized controlled trials of liver transplantation versus no therapy, the efficacy of this surgery is best assessed by carefully comparing postoperative survival with the known natural history of the disease in question. The best examples of this are in primary biliary cirrhosis and primary sclerosing cholangitis, for which well-validated disease-specific models of natural history are available. There are currently relatively few absolute contraindications to liver transplantation. These include severe cardiopulmonary disease, uncontrolled systemic infection, extrahepatic malignancy, severe psychiatric or neurological disorders, and absence of a viable splanchnic venous inflow system. One of the most frequently encountered contraindications to transplantation is ongoing destructive behavior caused by drug and alcohol addiction. The timing of the surgery can have a profound impact on the mortality and morbidity of patients undergoing liver transplantation. Because of the long waiting lists for donor organs, the need to project far in advance when transplantation might be required has proven to be one of the greatest challenges to those treating patients with end-stage liver disease. Three important questions must be addressed in a patient being considered for liver transplantation: (1) when should the patient be referred for possible transplantation? (2) when should the patient be listed for transplantation? and (3) when is the patient too sick to have a reasonable chance of surviving the perioperative period?

Clinical Use of a Bioartificial Liver in the Treatment of Acetaminophen-Induced Fulminant Hepatic Failure

Patients with acetaminophen-induced fulminant hepatic failure (FHF) who meet the King's College Hospital criteria have a high mortality risk (>90%) if they do not undergo liver transplantation. We have developed a treatment strategy for these patients based on the use of an extracorporeal bioartificial liver (BAD support system. In this study, we report the results of the clinical application of BAL support in patients with acetaminophen-induced FHF. All patients were admitted to a dedicated surgical intensive care unit. They were evaluated for urgent liver transplantation and received the standard medical measures, including N-acetylcysteine administration and intracranial pressure monitoring. Moreover, they underwent daily 6-hour BAL treatments. Eight patients were treated. Three patients were bridged to liver transplantation, and five patients recovered without a transplant. All patients experienced neurological and metabolic improvement after treatments with the BAL support system. The BAL support system seems to improve the outcome of high-risk patients with acetaminophen-induced FHF, even in the absence of liver transplantation. Avoiding liver transplantation is particularly important in an era of organ shortage and high cost of transplants.

Extracorporeal support and hepatocyte transplantation in acute liver failure and cirrhosis

The relative shortage of donor organs and lack of immediate availability mean that many patients with acute liver failure die before orthotopic liver transplantation can be performed. An effective temporary liver support system could improve the chance of survival with or without a transplant being ultimately carried out. Recent technological advances resulting in improved maintenance of hepatocyte viability and function in culture and bioreactor designs which facilitate adequate perfusion of the cellular component and removal of products of cellular metabolism have led to the development of a number of bioartificial devices for liver support. Three such devices have undergone preliminary clinical evaluation in the setting of acute liver failure, with a statistically significant reduction in raised intracerebral pressure along with improvements in consciousness level and some biochemical parameters associated with treatment with one of these. Several other devices with different characteristics have shown promise in vitro and/or in animal models but await clinical evaluation. Several new totally artificial systems have also been described, along with the emergence of isolated hepatocyte transplantation, with reports of successful 'bridging' to liver transplantation. Controlled trials on a multicentre basis in well-defined patient groups and with standardized outcome measures will be required to properly evaluate the clinical value of each of these approaches to providing liver support in acute liver failure and cirrhosis. A better understanding of mechanisms underlying multiorgan failure and of factors inhibiting liver regeneration, thereby allowing a more targeted approach, will be essential to the further development of effective liver support strategies in these settings.

Analysis of liver single photon emission computed tomography in a case of fulminant hepatic failure

Fulminant hepatic failure is associated with a high mortality rate. Thus, accurate assessment of hepatic functional reserve and hepatic regeneration is important. We describe a 67-year-old woman who survived subacute hepatic failure. We had an opportunity to monitor the clinical course of the patient using single photon emission computed tomography (SPECT) with 99mTc-galactosyl-human serum albumin (99mTc-GSA) and frequent hematological examinations. On admission, prothrombin time was remarkably prolonged (23.1% of control). The liver uptake of 99mTc-GSA was also considerably low. She responded well to treatment. Four weeks after admission, SPECT analysis showed a dramatic increase in liver uptake of 99mTc-GSA, suggesting promotion of hepatic regeneration. Moreover, functional liver volume calculated from the SPECT data showed a marked increase at 4 weeks after admission, whereas CT scan showed no change at that point. This indicated that SPECT with 99mTc-GSA reflected functional hepatocytes more accurately than liver volume determined by CT scan, which cannot exclude nonfunctional hepatocytes. The patient's condition improved in parallel with the improvements in the indices measured by SPECT and hematological examinations. SPECT analysis is practically useful for the prompt assessment of improvement in patients with fulminant hepatic failure.

Hepatocyte growth factor prevents endotoxin-induced lethal hepatic failure in mice

Sepsis and endotoxemia are involved in the development of fulminant hepatic failure, the prognosis of which is extremely poor and the mortality is high, with no available effective therapy. Here, we report that hepatocyte growth factor (HGF) exerts potent antiapoptotic effects in vivo and effectively prevents endotoxin-induced fulminant hepatic failure in mice. The animals were intraperitoneally injected three times with 120 micrograms human recombinant HGF or saline 6 hours and 30 minutes before and 3 hours after an intraperitoneal injection of lipopolysaccharide (LPS) and D-galactosamine (GalN). Administration of LPS + GalN, without HGF, rapidly led to massive hepatocyte apoptosis and severe liver injury, and all mice died of hepatic failure within 8 hours. In contrast, administration of human recombinant HGF strongly suppressed extensive progress of hepatocyte apoptosis and the liver injury induced by LPS + GalN, and 75% of the HGF-treated mice survived. Moreover, HGF strongly induced Bcl-xL expression and blocked apoptotic signal transduction upstream of CPP32 (caspase-3) in the liver, thereby leading to inhibition of massive hepatocyte apoptosis. We suggest that HGF may well have the potential to prevent fulminant hepatic failure, at least through its potent antiapoptotic action.

Inhibition of caspase activity prevents CD95-mediated hepatic microvascular perfusion failure and restores Kupffer cell clearance capacity

Using a murine model, we studied the effect of agonistic anti-CD95 antibodies (aCD95) on sinusoidal lining cells and a potential protection by caspase inhibition. C3H/HeN mice were intravenously administered aCD95 (10 microgram/mouse) or unspecific IgG (control) in the presence or absence of the caspase inhibitor z-VAD-fmk. Analysis of hepatic microcirculation using intravital fluorescence microscopy revealed severe (P<0.01) sinusoidal perfusion failure and reduced (P<0.05) phagocytic activity of Kupffer cells (KC) within 2 h. Transmission electron micrographs demonstrated loss of integrity of sinusoidal endothelial cells as early as 1 h after aCD95 application, whereas histological manifestation of hepatocellular apoptosis and hemorrhagic necrosis was most pronounced at 6 h. Blocking of caspase activity attenuated (P<0.01) both hepatic microvascular perfusion failure and KC dysfunction. Accordingly, full protection of the liver from apoptotic damage and intact microarchitecture was observed in histological sections after z-VAD-fmk treatment. Mortality rate was 40% 6 h after aCD95 administration, whereas all animals survived in the z-VAD-fmk group (P<0.05). The activation of caspases through CD95 may primarily lead to damage of sinusoidal endothelial cells and hepatic microvascular perfusion failure. Moreover, reduced phagocytic capacity of KC may contribute to accumulation of toxic metabolites released by dying cells at the local site of inflammation, further aggravating liver injury.

Overview of extracorporeal liver support systems and clinical results

Patients with acute liver failure (ALF) continue to have an almost 50% mortality rate despite improvements associated with the use of orthotopic liver transplantation (OLT). Numerous ex vivo methods have been developed in attempts to improve patient survival. These methods can be divided into three groups: detoxification (e.g., dialysis, charcoal adsorption, plasma exchange), which only provides excretory function; ex vivo liver perfusion (e.g., whole organ or tissue perfusion), which provides some metabolic function; and bioartificial or cell-based systems, which combine elements of the first two methods. Clinical trials have shown minimal efficacy of the various detoxification methods in terms of ALF patient survival, while the relative success of OLT has shown the importance of providing metabolic as well as excretory functions. Attempts to provide those additional functions with ex vivo tissue perfusion have been fraught with complications such as clotting and acute tissue rejection, leading to the conceptual development of cell-based bioreactor systems. A number of these bioartificial systems have been clinically evaluated, and the preliminary patient survival rates have encouraged further work in this area.