Acute liver failure

NOD2-mediated HDAC6/NF-κb signalling pathway regulates ferroptosis induced by extracellular histone H3 in acute liver failure

Acute liver failure (ALF) is life-threatening and often associated with high mortality rates. The aim of the present study was to investigate whether extracellular histone H3 could induce ferroptosis in hepatic macrophages in ALF and explore its potential mechanism. RAW264.7 macrophages and C57BL/6 mice were used in this study. LPS, D-galactosamine (D-Gal), histone H3, histone H3 antibody, NOD2 agonist Muramyl Dipeptide (MDP) and HDAC6-siRNA were administered in this study. The key molecules of ferroptosis, NOD2, HDAC6 and the NF-κb pathway, were detected. In vitro, histone H3 was released into the extracellular environment from cell nucleus after LPS exposure. In addition, histone H3 could induce ferroptosis in RAW264.7 macrophages with increased level of Fe²⁺ and ROS and decreased levels of GPX4 and GSH. MDP further aggravated ferroptosis in RAW264.7 macrophages stimulated by histone H3, which was accompanied by elevated NOD2, HDAC6, p-P65 and IκBα. HDAC6-siRNA ameliorated ferroptosis in RAW264.7 macrophages induced by histone H3, which was accompanied by decreased levels of HDAC6, p-P65 and IκBα. However, HDAC6-siRNA did not alter NOD2 levels in RAW264.7 macrophages administered histone H3. In vivo, the levels of NOD2, HDAC6 the NF-κb pathway and ferroptosis were increased in ALF mice, which were downregulated by histone H3 antibody and upregulated by histone H3. Extracellular histone H3 could induce ferroptosis in hepatic macrophages in ALF by regulating theNOD2-mediated HDAC6/NF-κb signalling pathway.

Acute Liver Failure: From Textbook to Emergency Room and Intensive Care Unit With Concomitant Established and Modern Novel Therapies

Acute liver failure is a rare hepatic emergent situation that affects primarily young people and has often a catastrophic or even fatal outcome. Definition of acute liver failure has not reached a universal consensus and the interval between the appearance of jaundice and hepatic encephalopathy for the establishment of the acute failure is a matter of debate. Among the wide variety of causes, acetaminophen intoxication in western societies and viral hepatitis in the developing countries rank at the top of the etiology list. Identification of the clinical appearance and initial management for the stabilization of the patient are of vital significance. Further advanced therapies, that require intensive care unit, should be offered. The hallmark of treatment for selected patients can be orthotopic liver transplantation. Apart from well-established treatments, novel therapies like hepatocyte or stem cell transplantation, additional new therapeutic strategies targeting acetaminophen intoxication and/or hepatic encephalopathy are mainly experimental, and some of them do not belong, yet, to clinical practice. For clinicians, it is substantial to have the alertness to timely identify the patient and transfer them to a specialized center, where more treatment opportunities are available.

Complement System as a Target for Therapies to Control Liver Regeneration/Damage in Acute Liver Failure Induced by Viral Hepatitis

The complement system plays an important role in innate immunity inducing liver diseases as well as signaling immune cell activation in local inflammation regulating immunomodulatory effects such as liver damage and/or liver regeneration. Our aim is to evaluate the role of complement components in acute liver failure (ALF) caused by viral hepatitis, involving virus-induced ALF in human subjects using peripheral blood, samples of liver tissues, and ex vivo assays. Our findings displayed low levels of C3a in plasma samples with high frequency of C3a, C5a, and C5b/9 deposition in liver parenchyma. Meanwhile, laboratory assays using HepG2 (hepatocyte cell line) showed susceptibility to plasma samples from ALF patients impairing in vitro cell proliferation and an increase in apoptotic events submitting plasma samples to heat inactivation. In summary, our data suggest that the complement system may be involved in liver dysfunction in viral-induced acute liver failure cases using ex vivo assays. In extension to our findings, we provide insights into future studies using animal models for viral-induced ALF, as well as other associated soluble components, which need further investigation.

Immune reconstitution inflammatory syndrome as a cause of autoimmune hepatitis and acute liver failure

Acute liver failure is a rare syndrome with high mortality and is often diagnosed late. Intensivist physicians play fundamental roles in the diagnostic suspicion and the management of the multiple-organic dysfunctions characteristic of this entity. Immune reconstitution inflammatory syndrome is an entity that is characterized by the paradoxical worsening of the patient's previous condition, after the initiation of antiretrovirals, triggered against either pathogens present in the host or autoantigens. Autoimmune hepatitis has recently been described as one of these autoimmune manifestations. The authors report the first case with evolution to acute liver failure and death within a few days after the development of encephalopathy, review the cases of autoimmune hepatitis described and comment on the therapeutic possibilities in this context.

Comparison of the Results of Living Donor Liver Transplantation Due to Acute Liver Failure and Biliary Atresia in a Quaternary Center

OBJECTIVE

The objective of this study was to compare the complications, outcomes, and survival prevalence in patients undergoing living donor liver transplantation due to biliary atresia (BA) or acute liver failure (ALF).

RESULTS

In the period of June 1998-July 2016, 199 children underwent living transplantation due to BA or ALF. Of these 199, 184 were included in the analysis. The average age, weight, and body mass index of BA patients were lower than those of ALF (P < .001). The chi-square test showed a higher prevalence of infection in transplant recipients due to BA (P = .0001) and a higher prevalence of hepatic artery stenosis in those who underwent transplantation due to ALF (P = .001). In the multivariate analysis, the infection remains statistically more prevalent in the BA group (95% confidence interval [CI], 0.20-0.60), while hepatic artery stenosis loses significance. The mortality rate was similar in both groups and the survival in 5 years also. The prevalence of hepatic artery thrombosis, portal vein thrombosis/stenosis, biliary stenosis, and acute and chronic cellular rejection showed no statistical difference between the two groups.

CONCLUSION

Living donor liver transplantation should be a valid option in cases of fulminant hepatitis with an indication for liver transplantation, especially in places where the number of cadaverous donors is low and the length of time on the waiting list is high.

Hepatoprotective Effects of Kaempferol-3-O-α-l-Arabinopyranosyl-7-O-α-l-Rhamnopyranoside on d-Galactosamine and Lipopolysaccharide Caused Hepatic Failure in Mice

Fulminant hepatic failure (FHF), associated with high mortality, is characterized by extensive death of hepatocytes and hepatic dysfunction. There is no effective treatment for FHF. Several studies have indicated that flavonoids can protect the liver from different factor-induced injury. Previously, we found that the extracts of Elaeagnus mollis leaves had favorable protective effects on acute liver injury. However, the role and mechanisms behind that was elusive. This study examined the hepatoprotective mechanisms of kaempferol-3-O-α-l-arabinopyranosyl-7-O-α-l-rhamnopyra-noside (KAR), a major flavonol glycoside of E. mollis, against d-galactosamine (GalN) and lipopolysaccharide (LPS)-induced hepatic failure. KAR reduces the mouse mortality, protects the normal liver structure, inhibits the serum aspartate aminotransferase (AST) and alamine aminotransferase (ALT) activity and decreases the production of malondialdehyde (MDA) and reactive oxygen species (ROS) and inflammatory cytokines, TNF-α, IL-6, and IL-1β. Furthermore, KAR inhibits the apoptosis of hepatocytes and reduces the expression of TLR4 and NF-κB signaling pathway-related proteins induced by GalN/LPS treatment. These findings suggest that the anti-oxidative, anti-inflammatory, and anti-apoptotic effects of KAR on GalN/LPS-induced acute liver injury were performed through down-regulating the activity of the TLR4 and NF-κB signaling pathways.

Liver transplantation: need, indications, patient selection and pre-transplant care

Chronic or acute liver failure and primary liver cancers can be effectively managed with liver transplantation. The range of indications for liver transplantation is increasing but there is a mismatch between the numbers of available donations and current needs. Specific criteria for listing patients exist but, at minimum, the predicted mortality without transplantation must exceed that with transplantation, coupled with a 50% predicted 5-year survival following liver transplantation. The risk posed by liver disease must be weighed against the risk of liver transplantation, considering the patient's comorbidities, age, nutritional status and behavioural factors in a complex assessment process. This article reviews current UK practice in the selection and care of patients being assessed for liver transplantation.

Artificial liver support in pigs with acetaminophen-induced acute liver failure

AIM

To establish a reversible porcine model of acute liver failure (ALF) and treat it with an artificial liver system.

METHODS

Sixteen pigs weighing 30-35 kg were chosen and administered with acetaminophen (APAP) to induce ALF. ALF pigs were then randomly assigned to either an experimental group (n = 11), in which a treatment procedure was performed, or a control group (n = 5). Treatment was started 20 h after APAP administration and continued for 8 h. Clinical manifestations of all animals, including liver and kidney functions, serum biochemical parameters and survival times were analyzed.

RESULTS

Twenty hours after APAP administration, the levels of serum aspartate aminotransferase, total bilirubin, creatinine and ammonia were significantly increased, while albumin levels were decreased (P < 0.05). Prothrombin time was found to be extended with progression of ALF. After continuous treatment for 8 h (at 28 h), aspartate aminotransferase, total bilirubin, creatinine, and ammonia showed a decrease in comparison with the control group (P < 0.05). A cross-section of livers revealed signs of vacuolar degeneration, nuclear fragmentation and dissolution. Concerning survival, porcine models in the treatment group survived for longer times with artificial liver system treatment (P < 0.05).

CONCLUSION

This model is reproducible and allows for quantitative evaluation of new liver systems, such as a bioartificial liver. The artificial liver system (ZHJ-3) is safe and effective for the APAP-induced porcine ALF model.

Deregulation of Regulatory T Cells in Acute-on-Chronic Liver Failure: A Rat Model

Aims. Acute-on-chronic liver failure (ACLF) and acute liver failure (ALF) are similar in many respects during their acute exacerbation; however, ACLF generally has a poorer prognosis. We aimed to investigate the role and dynamic changes of regulatory T cell (Treg) and T helper 17 (Th17) cell proportions during ACLF progress. Methods. All rats were classified into two groups randomly: ACLF group and ALF group (control group). The rat model of ACLF was preestablished by intraperitoneal injection of carbon tetrachloride for 2 months. Then acute liver injury was induced by combined D-galactosamine and lipopolysaccharide. Six time points were examined before or after acute induction. Liver samples were performed with hematoxylin-eosin and Masson staining; circulatory Treg and Th17 cell frequencies were determined using flow cytometry assays; serum levels of alanine aminotransferase, aspartate aminotransferase, interleukin-10 (IL-10), and interferon-γ (IFN-γ) were examined. Results. In group ACLF, both Th17 cell proportion and IFN-γ level presented upgrade firstly and then descend latter tendency; the trends of Treg cell proportion and IL-10 level were observed to gradually decrease and became stable. Conclusion. The Treg cells played an important role in the immunologic mechanism during the process of ACLF. And the function of Treg cells in ACLF was defective.

Superior performance of co-cultured mesenchymal stem cells and hepatocytes in poly(lactic acid-glycolic acid) scaffolds for the treatment of acute liver failure

Recently, cell-based therapies have attracted attention as promising treatments for acute liver failure (ALF). Bone marrow-derived mesenchymal stem cells (MSCs) are potential candidates for co-culture with hepatocytes in poly(lactic acid-glycolic acid) (PLGA) scaffolds to support hepatocellular function. However, the mechanism of culturing protocol using PLGA scaffolds for MSC differentiation into hepatocyte-like cells as well as the therapeutic effect of cell seeded PLGA scaffolds on ALF remain unsatisfactory in clinical application. Here, MSCs and hepatocytes were co-cultured at ratios of 1:2.5 (MSCs: Hep), 1:5 and 1:10, respectively. The proliferation abilities of these co-cultured cells were detected by CCK8, MTT, EdU and by scanning electron microscopy (SEM), and the ability of MSCs to differentiate into hepatocytes was detected by PCR, western blot and immunofluorescence staining. Therapeutic trials of cell seeded PLGA scaffolds were conducted through mouse abdominal cavity transplantation. Results showed that the 1:5 group showed significantly higher cellular proliferation than the 1:2.5 and 1:10 groups, supernatant albumin and urea nitrogen levels were also significantly higher in the 1:5 group than in other two groups. Similarly, the 1:5 group demonstrated better DNA transcription and liver-specific protein (albumin, CK18 and P450) production. Meanwhile, the GalN-stimulated levels of ALT, AST and TBil in mouse serum were down-regulated significantly more by (MSC  +  Hep)-PLGA scaffold treatment than MSC-PLGA or Hep-PLGA scaffold treatments. Furthermore, the (MSC  +  Hep)-PLGA scaffold-treated ALF mice showed a lower immunogenic response level than the other two groups. These data suggested that the ratio of 1:5 (MSC:Hep) co-cultures was the optimal ratio for MSCs to support hepatocellular metabolism and function in PLGA scaffolds in vitro, the (MSC  +  Hep)-PLGA scaffold treatment could perform better restoration for damaged liver function and could give ALF mice a greater survival rate than the monocell seeded PLGA scaffold treatment.

Liver Stem Cells: Experimental Findings and Implications for Human Liver Disease

Evidence from human histopathology and experimental studies with rodents and zebrafish has shown that hepatocytes and cholangiocytes may function as facultative stem cells for each other in conditions of impaired regeneration. The interpretation of the findings derived from these studies has generated considerable discussion and some controversies. This review examines the evidence obtained from the different experimental models and considers implications that these studies may have for human liver disease.

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).

METHODS: An experimental rat model of galactosamine-induced AHF was used. An inhibitor of NO synthase, nitroarginine methyl ester, or an NO donor, arginine, were administered at various doses prior to or after the induction of AHF.

RESULTS: All tested groups developed AHF. Following inhibition of the endogenous NO pathway, most liver parameters improved, regardless of the inhibitor dose before the induction of liver damage, and depending on the inhibitor dose after liver damage. Prophylactic administration of the inhibitor was more effective in improving liver function parameters than administration of the inhibitor after liver damage. An attempt to activate the endogenous NO pathway prior to the induction of liver damage did not change the observed liver function parameters. Stimulation of the endogenous NO pathway after liver damage, regardless of the NO donor dose used, improved most liver function parameters.

CONCLUSION: The endogenous NO pathway plays an important role in the development of experimental galactosamine-induced AHF.

In vivo siRNA delivery of Keap1 modulates death and survival signaling pathways and attenuates concanavalin-A-induced acute liver injury in mice

Oxidative stress contributes to the progression of acute liver failure (ALF). Transcription factor nuclear factor-erythroid 2-related factor (Nrf2) serves as an endogenous regulator by which cells combat oxidative stress. We have investigated liver damage and the balance between death and survival signaling pathways in concanavalin A (ConA)-mediated ALF using in vivo siRNA delivery targeting Keap1 in hepatocytes. For that goal, mice were injected with Keap1- or luciferase-siRNA-containing liposomes via the tail vein. After 48 hours, ALF was induced by ConA. Liver histology, pro-inflammatory mediators, antioxidant responses, cellular death, and stress and survival signaling were assessed. Keap1 mRNA and protein levels significantly decreased in livers of Keap1-siRNA-injected mice. In these animals, histological liver damage was less evident than in control mice when challenged with ConA. Likewise, markers of cellular death (FasL and caspases 8, 3 and 1) decreased at 4 and 8 hours post-injection. Nuclear Nrf2 and its target, hemoxygenase 1 (HO1), were elevated in Keap1-siRNA-injected mice compared with control animals, resulting in reduced oxidative stress in the liver. Similarly, mRNA levels of pro-inflammatory cytokines were reduced in livers from Keap1-siRNA-injected mice. At the molecular level, activation of c-jun (NH2) terminal kinase (JNK) was ameliorated, whereas the insulin-like growth factor I receptor (IGFIR) survival pathway was maintained upon ConA injection in Keap1-siRNA-treated mice. In conclusion, our results have revealed a potential therapeutic use of in vivo siRNA technology targeted to Keap1 to combat oxidative stress by modulating Nrf2-mediated antioxidant responses and IGFIR survival signaling during the progression of ALF.