An overview of animal models for investigating the pathogenesis and therapeutic strategies in acute hepatic failure

Acute hepatic failure (AHF) is a severe liver injury accompanied by hepatic encephalopathy which causes multiorgan failure with an extremely high mortality rate, even if intensive care is provided. Management of severe AHF continues to be one of the most challenging problems in clinical medicine. Liver transplantation has been shown to be the most effective therapy, but the procedure is limited by shortage of donor organs. Although a number of clinical trials testing different liver assist devices are under way, these systems alone have no significant effect on patient survival and are only regarded as a useful approach to bridge patients with AHF to liver transplantation. As a result, reproducible experimental animal models resembling the clinical conditions are still needed. The three main approaches used to create an animal model for AHF are: surgical procedures, toxic liver injury and infective procedures. Most common models are based on surgical techniques (total/partial hepatectomy, complete/transient devascularization) or the use of hepatotoxic drugs (acetaminophen, galactosamine, thioacetamide, and others), and very few satisfactory viral models are available. We have recently developed a viral model of AHF by means of the inoculation of rabbits with the virus of rabbit hemorrhagic disease. This model displays biochemical and histological characteristics, and clinical features that resemble those in human AHF. In the present article an overview is given of the most widely used animal models of AHF, and their main advantages and disadvantages are reviewed.

Arterial steroid injection therapy can inhibit the progression of severe acute hepatic failure toward fulminant liver failure

AIM: To utilize transcatheter arterial steroid injection therapy (TASIT) via the hepatic artery to reduce hepatic macrophage activity in patients with severe acute hepatic failure.METHODS: Thirty-four patients with severe acute hepatic failure were admitted to our hospital between June 2002 to June 2006 providing for the possibility of liver transplantation (LT). Seventeen patients were treated using traditional liver supportive procedures, and the other 17 patients additionally underwent TASIT with 1000 mg methylprednisolone per day for 3 continuous days. RESULTS: Of the 17 patients who received TASIT, 13 were cured without any complications, 2 died, and 2 underwent LT. Of the 17 patients who did not receive TASIT, 4 were self-limiting, 7 died, and 6 underwent LT. Univariate logistic analysis revealed that ascites, serum albumin, prothrombin time, platelet count, and TASIT were significant variables for predicating the prognosis. Multivariate logistic regression analysis using stepwise variable selection showed that prothrombin time, platelet count, and TASIT were independent predictive factors. CONCLUSION: TASIT might effectively prevent the progression of severe acute hepatic failure to a fatal stage of fulminant liver failure.

Are heat stroke and physical exhaustion underestimated causes of acute hepatic failure?

While cardiopulmonary symptoms are common in patients undergoing dassical or, due to physical exercise, exertional heat stroke, the failure of other organs is a rarely described phenomenon. Here we present two cases of acute hepatic failure, one due to classic heat shock, while the other occurred while the patient was doing a marathon-type running. Both cases presented with very high transaminases and significantly elevated international normalized ratio （INR）. No other causes for liver failure could be identified but physical exhaustion and hyperthermia.

Mesenchymal stem cells rescue acute hepatic failure by polarizing M2 macrophages

AIM To investigate whether M1 or M2 polarization contributes to the therapeutic effects of mesenchymal stem cells(MSCs) in acute hepatic failure(AHF).METHODS MSCs were transfused into rats with AHF induced by D-galactosamine(DGal N). The therapeutic effects of MSCs were evaluated based on survival rate and hepatocyte proliferation and apoptosis. Hepatocyte regeneration capacity was evaluated by the expression of the hepatic progenitor surface marker epithelial cell adhesion molecule(Ep CAM). Macrophage polarization was analyzed by M1 markers [CD68,tumor necrosis factor alpha(TNF-α),interferon-γ(IFN-γ),inducible nitric oxide synthase(INOS)] and M2 markers [CD163,interleukin(IL)-4,IL-10,arginase-1(Arg-1)] in the survival and death groups after MSC transplantation.RESULTS The survival rate in the MSC-treated group was increased compared with the DPBS-treated control group(37.5% vs 10%). MSC treatment protected rats with AHF by reducing apoptotic hepatocytes and promoting hepatocyte regeneration. Immunohistochemical analysis showed that MSC treatment significantly increased the expression of Ep CAM compared with the control groups(P < 0.001). Expression of Ep CAM in the survival group was significantly up-regulated compared with the death group after MSC transplantation(P = 0.003). Transplantation of MSCs significantly improved the expression of CD163 and increased the gene expression of IL-10 and Arg-1 in the survival group. IL-4 concentrations were significantly increased compared to the death group after MSC transplantation(88.51 ± 24.51 pg/m L vs 34.61 ± 6.6 pg/m L,P < 0.001). In contrast,macrophages showed strong expression of CD68,TNF-α,and INOS in the death group. The concentration of IFN-γ was significantly increased compared to the survival group after MSC transplantation(542.11 ± 51.59 pg/m L vs 104.07 ± 42.80 pg/m L,P < 0.001).CONCLUSION M2 polarization contributes to the therapeutic effects of MSCs in AHF by altering levels of anti-inflammatory and pro-inflammatory factors.

Hepatoprotective effects of cathepsin B inhibitor on acute hepatic failure induced by lipopolysaccharide/D-galactosamine in mice

BACKGROUND:Increasing evidence suggests that the inactivation of cathepsin B attenuates hepatocyte apoptosis and liver damage.This study aimed to investigate the protective effects of a cathepsin B inhibitor(CA-074me) on lipopolysaccharide(LPS)/D-galactosamine(D-GalN)-induced acute hepatic failure(AHF) in mice.METHODS:Mice were intraperitoneally injected with a combination of LPS/D-GalN to induce AHF with or without CA-074me pretreatment.The cumulative survival rates were calculated 48 hours after the induction of AHF.As well as changes in biochemical indicators and liver histology,hepatocyte apoptosis was assessed using a TUNEL method.Serum tumor necrosis factor-α(TNF-α) production,caspase-3,caspase-8,and caspase-9 activity was evaluated.Cytosolic cytochrome c and Bcl-2 expression were measured by Western blotting.RESULTS:The marked elevation in serum aminotransferase activity and prothrombin time found in LPS/D-GalN-treated mice was significantly improved by pretreatment with CA074me.The efficacy of CA-074me was also confirmed by histological analysis and TUNEL assay.The survival rate significantly improved in LPS/D-GalN-induced mice given CA-074me compared with untreated mice.LPS/D-GalNinduced caspase-3 and caspase-9 activation was remarkably suppressed by CA-074me.However,the increased levels of serum TNF-α and elevated caspase-8 activity in AHF mice were not significantly reduced by CA-074me.Moreover,CA074me sharply reduced the increased expression of cytosolic cytochrome c and markedly augmented Bcl-2 expression.CONCLUSION:These results suggest that CA-074me has a protective effect in acute hepatic failure induced by LPS/D-GalN.

Efficacy of liver transplantation for acute hepatic failure:asingle-center experience

BACKGROUND:Acute hepatic failure (AHF) is a devastating clinical syndrome with a high mortality rate.The outcome of AHF varies with etiology,but liver transplantation (LT) can significantly improve the prognosis and survival rate of such patients.This study aimed to detect the role of LT and artificial liver support systems (ALSS) for AHF patients and to analyze the etiology and outcome of patients with this disease.METHODS:A retrospective analysis was made of 48 consecutive patients with AHF who fulfilled the Kings College Criteria for LT at our center.We analyzed and compared the etiology,outcome,prognosis,and survival rates of patients between the transplantation (LT) group and the non-transplantation (N-LT) group.RESULTS:AHF was due to viral hepatitis in 25 patients (52.1%;hepatitis B virus in 22),drug or toxic reactions in 14 (29.2%;acetaminophen in 6),Wilson disease in 4 (8.3%),unknown reasons in 3 (6.3%),and miscellaneous conditions in 2 (4.2%).In the LT group,36 patients (7 underwent living donor LT,and 29 cadaveric LT) had an average model for endstage liver disease score (MELD) of 35.7.Twenty-eight patients survived with good graft function after a follow-up of 27.3± 4.5 months.During the waiting time,6 patients were treated with ALSS and 2 of them died during hospitalization.The 30-day,12-month,and 18-month survival rates were 77.8%,72.2%,and 66.7%,respectively.In the N-LT group,12 patients had an average MELD score of 34.5.Four patients were treated with ALSS and all died during hospitalization.The 90-day and 1-year survival rates were only 16.7% and 8.3%,respectively.CONCLUSIONS:Hepatitis is the most prominent cause of AHF at our center.Most patients with AHF,who fulfill the Kings College Criteria for LT,did not survive longer without LT.ALSS did not improve the prognosis of AHF patients,but may extend the waiting time for a donor.Currently,LT is still the most effective way to improve the prognosis of AHF patients.

Differential Gene Expression Profiles in Acute Hepatic Failure Model in Mice Infected with MHV-3 Virus Intervened by Anti-hepatic Failure Compound

Differential gene expression profiles in Balb/cJ mouse model of acute hepatic failure infected with MHV-3 virus intervened by anti-hepatic failure compound （AHFC） and the changes of cytokines regulated by genes were investigated. The Balb/cj mice were divided into AHFC-intervened group and control group randomly. Acute hepatic failure model of Balb/cJ mice infected with MHV-3 virus was established. The survival rate in the two groups was observed. It was found that the survival rate in the AHFC-intervened group and control group was 90% and 50% respectively 48 h after intraperitoneal injection of MHV-3 （P〈0.05）. Before and after the experiment, the cytokines in peripheral blood of the survival mice were determined, and RNA was extracted from survival mouse liver tissue for the analysis of the differential gene expression by a 36 kb mouse oligonuleotide DNA array. In all the genes of microarray there were 332 genes expressed differently in the two groups, in which 234 genes were up-regulated and 78 genes down-regulated. Through clustering analysis, the differential expression of immune related genes, including TNF receptor superfamily, Kctd9, Bcl-2, Fgl2, IL-8, IL-6, IFN-7, TNF-α etc. might be related with the curative effectiveness of AHFC. It was suggested that AHFC can balance the immune state of mouse model of acute hepatic failure infected with MHV-3 virus mainly through regulating the expression of immune related genes, decrease the immune damage and inhibit liver cell apoptosis of mouse acute hepatic failure model obviously so as to increase the survival rate of mouse models of acute hepatic failure.

Hepatoprotective effect of nitric oxide in experimental model of acute hepatic failure

AIM: To evaluate the effect of nitric oxide (NO) on the development and degree of liver failure in an animal model of acute hepatic failure (AHF).

Subacute fulminant hepatic failure with intermittent fever

BACKGROUND: Viral hepatitis B accounts for over 80% of acute hepatic failures in China and the patients die mainly of its complications. A patient with hepatic failure and fever is not uncommon, whereas repeated fever is rare. METHODS: A 32-year-old female was diagnosed with subacute hepatic failure and hepatitis B viral infection because of hyperbilirubinemia, coagulopathy, hepatic encephalopathy, serum anti-HBs-positive without hepatitis B vaccination, and typical intrahepatic pathological features of chronic hepatitis B. Plasma exchange was administered twice and she awoke with hyperbilirubinemia and discontinuous fever. RESULTS: Urethritis was confirmed and medication-induced fever and/or spontaneous bacterial peritonitis (Gram-negative bacillus infection) was suspected. The patient was treated with antibiotics, steroids and a Chinese herbal medicine, matrine, for three months and she recovered. CONCLUSION: The survival rate of patients with hepatic failure might be improved with comprehensive supporting measures and appropriate, timely management of complications.

Transplantation of microencapsulated umbilical-cord-blood-derived hepatic-like cells for treatment of hepatic failure

AIM: To investigate intraperitoneal transplantation of microencapsulated hepatic-like cells from human umbilical cord blood for treatment of hepatic failure in rats. METHODS: CD34+ cells in umbilical cord blood cells were isolated by magnetic cell sorting. In the in vitro experiment, sorted CD34+ cells were amplified and induced into hepatic-like cells by culturing with a combination of fibroblast growth factor 4 and hepatocyte growth factor. Cultures without growth factor addition served as controls. mRNA and protein levels for hepatic-like cells were analyzed by reverse transcription-polymerase chain reaction, immunohistochemistry and immunofluorescence. In the in vivo experiment, the hepatic-like cells were encapsulated and transplanted into the abdominal cavity of acute hepatic failure (AHF) rats at 48 h after D-galactosamine induction of acute hepatic failure. Transplantation with PBS and unencapsulated hepatic-like cells served as controls. The mortality rate, hepatic pathological changes and serum biochemical indexes were determined. The morphology and structure of microcapsules in the greater omentum were observed. RESULTS: Human albumin, alpha-fetoprotein and GATA-4 mRNA and albumin protein positive cells were found among cultured cells after 16 d. Albumin level in culture medium was significantly increased after culturing with growth factors in comparison with culturing without growth factor addition (P < 0.01). Compared with the unencapsulated group, the mortality rate of the encapsulated hepatic-like cell-transplanted group was significantly lower (P < 0.05). Serum biochemical parameters, alanine aminotransferase, aspartate aminotransferase and total bilirubin in the encapsulated group were significantly improvement compared with the PBS control group (P < 0.01). Pathological staining further supported these findings. At 1-2 wk post-transplantation, free microcapsules with a round clear structure and a smooth surface were observed in peritoneal lavage fluid, surviving cells inside microcapsules were found by trypan blue staining, but some fibrous tissue around microcapsules was also detected in the greater omentum of encapsulated group by hematoxylin and eosin staining. CONCLUSION: Transplantation of microencapsulated hepatic-like cells derived from umbilical cord blood cells could preliminarily alleviate the symptoms of AHF rats.

Acute-on-chronic liver failure：recent update

Acute on chronic liver failure（ACLF） was first described in 1995 as a clinical syndrome distinct to classic acute decompensation.Characterized by complications of decompensation,ACLF occurs on a background of chronic liver dysfunction and is associated with high rates of organ failure and significant short-term mortality estimated between45%and 90%.Despite the clinical relevance of the condition,it still remains largely undefined with continued disagreement regarding its precise etiological factors,clinical course,prognostic criteria and management pathways.It is concerning that,despite our relative lack of understanding of the condition,the burden of ACLF among cirrhotic patients remains significant with an estimated prevalence of 30.9%.This paper highlights our current understanding of ACLF,including its etiology,diagnostic and prognostic criteria and pathophysiology.It is evident that further refinement of the ACLF classification system is required in order to detect high-risk patients and improve short-term mortality rates.The field of metabolomics certainly warrants investigation to enhance diagnostic and prognostic parameters,while the use of granulocyte-colony stimulating factor is a promising future therapeutic intervention for patients with ACLF.

Hepatitis E virus-related acute liver failure associated with pure red cell aplasia

The Editor welcomes submissions for possible publication in the Letters to the Editor section. Letters commenting on an article published in the Journal or other interesting pieces will be considered if they are received within 6 weeks of the time the article was published. Authors of the article being commented on will be given an opportunity to offer a timely response to the letter. Authors of letters will be notified that the letter has been received. Unpublished letters cannot be returned.

The Pathogenesis of Acute on Chronic Hepatitis B liver Failure

Acute-on-chronic liver failure is a characteristic clinical liver syndrome, which should be differentiated from acute liver failure, acute decompensated liver cirrhosis and chronic liver failure. The pathogenesis of ACLF is not fully understood yet. Viral factors and immune injury have been reported to be the two major pathogenesis. This paper reviewed the researches on the pathogenesis of acute on chronic hepatitis B liver failure in recent years, to provide theoretical basis for prompt and accurate diagnosis and treatment of this syndrome. This would benefit for the prognosis and raise the survival rate of patients.

Study on the role of autophagy in the occurrence and development of liver diseases

Autophagy is a process of lysosome degradation,which plays an important role in maintaining cell homeostasis and organ integrity through the degradation of misfolded proteins,removal of damaged organelles and excess lipids,which is one of the research hotspots in recent years.Liver disease often develops into chronic disease with high mortality,which seriously affects the life safety and quality of life of patients.Studies have shown that autophagy participates in the processes of cellular immunity and oxidative stress,plays an important role in a variety of liver diseases,has the characteristics of two-way regulation,and moderate autophagy has a protective effect.Excessive or dysfunctional autophagy can promote cell death and lead to the occurrence and development of the disease.at present,regulating autophagy is considered as a potential treatment.Based on chronic viral hepatitis,liver fibrosis,non-alcoholic fatty liver disease,acute liver failure and primary liver cancer,this paper reviews the functional characteristics and regulatory mechanism of autophagy in liver diseases.to explore new therapeutic targets for liver diseases,in order to provide new ideas and basis for clinical diagnosis and treatment.