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Acute liver failure (ALF) is a rare, acute, potentially reversible condition resulting in severe liver impairment and rapid clinical deterioration in patients without preexisting liver disease. Due to the rarity of this condition, published studies are limited by the use of retrospective or prospective cohorts and lack of randomized controlled trials. Current guidelines represent the suggested approach to the identification, treatment, and management of ALF and represent the official practice recommendations of the American College of Gastroenterology. The scientific evidence was reviewed using the Grading of Recommendations, Assessment, Development and Evaluation process to develop recommendations. When no robust evidence was available, expert opinions were summarized using Key Concepts. Considering the variety of clinical presentations of ALF, individualization of care should be applied in specific clinical scenarios.

Acute liver failure is a rare disorder with high mortality and resource cost. In the developing world, viral causes predominate, with hepatitis E infection recognised as a common cause in many countries. In the USA and much of western Europe, the incidence of virally induced disease has declined substantially in the past few years, with most cases now arising from drug-induced liver injury, often from paracetamol. However, a large proportion of cases are of unknown origin. Acute liver failure can be associated with rapidly progressive multiorgan failure and devastating complications; however, outcomes have been improved by use of emergency liver transplantation. An evidence base for practice is emerging for supportive care, and a better understanding of the pathophysiology of the disorder, especially in relation to hepatic encephalopathy, will probably soon lead to further improvements in survival rates.

Acute and acute-on-chronic liver failure (ALF and ACLF), though distinct clinical entities, are considered syndromes of innate immune dysfunction. Patients with ALF and ACLF display evidence of a pro-inflammatory state with local liver inflammation, features of systemic inflammatory response syndrome (SIRS) and vascular endothelial dysfunction that drive progression to multi-organ failure. In an apparent paradox, these patients are concurrently immunosuppressed, exhibiting acquired immune defects that render them highly susceptible to infections. This paradigm of tissue injury succeeded by immunosuppression is seen in other inflammatory conditions such as sepsis, which share poor outcomes and infective complications that account for high morbidity and mortality. Monocyte and macrophage dysfunction are central to disease progression of ALF and ACLF. Activation of liver-resident macrophages (Kupffer cells) by pathogen and damage associated molecular patterns leads to the recruitment of innate effector cells to the injured liver. Early monocyte infiltration may contribute to local tissue destruction during the propagation phase and results in secretion of pro-inflammatory cytokines that drive SIRS. In the hepatic microenvironment, recruited monocytes mature into macrophages following local reprogramming so as to promote resolution responses in a drive to maintain tissue integrity. Intra-hepatic events may affect circulating monocytes through spill over of soluble mediators and exposure to apoptotic cell debris during passage through the liver. Hence, peripheral monocytes show numerous acquired defects in acute liver failure syndromes that impair their anti-microbial programmes and contribute to enhanced susceptibility to sepsis. This review will highlight the cellular and molecular mechanisms by which monocytes and macrophages contribute to the pathophysiology of ALF and ACLF, considering both hepatic inflammation and systemic immunosuppression. We identify areas for further research and potential targets for immune-based therapies to treat these devastating conditions.

BackgroundA nationwide survey was performed to clarify the recent status of acute liver failure (ALF) and late-onset hepatic failure (LOHF) in Japan.MethodsTwo-step surveys for patients with ALF and LOHF meeting the Japanese diagnostic criteria were performed annually in 782 hospitals. The clinical features of the patients were then compared to those reported in previous surveys.ResultsIn total, 1554 and 49 patients with ALF and LOHF, respectively, who were seen between 2010 and 2015 were enrolled. The subjects were classified into 1280 patients with hepatitis (642 non-comatose and 638 comatose) and 323 patients without hepatitis (190 non-comatose and 133 comatose). Compared with patients seen between 1998 and 2009, an older patient age and a higher percentage of underlying extrahepatic disease were observed. Although hepatitis virus infection was the most frequent etiology, the percentage of patients with this etiology had decreased, compared with previous cohorts, while the percentages of patients with drug-induced liver injuries, autoimmune hepatitis, and an indeterminate etiology had increased. Liver transplantation was performed in 170 patients (10.6%), whereas artificial liver support with plasmapheresis and/or hemodiafiltration were performed for most of the comatose patients. The outcomes of comatose patients were unfavorable, similar to previous surveys, especially the outcomes of hepatitis B virus carriers, including those with de novo hepatitis B (survival rate of 5.4% without liver transplantation).ConclusionAlthough the clinical features, including the etiologies, of patients with ALF and LOHF have changed, the outcomes of patients have not improved in recent years.

Acute liver failure is a rare and severe consequence of abrupt hepatocyte injury, and can evolve over days or weeks to a lethal outcome. A variety of insults to liver cells result in a consistent pattern of rapid-onset elevation of aminotransferases, altered mentation, and disturbed coagulation. The absence of existing liver disease distinguishes acute liver failure from decompensated cirrhosis or acute-on-chronic liver failure. Causes of acute liver failure include paracetamol toxicity, hepatic ischaemia, viral and autoimmune hepatitis, and drug-induced liver injury from prescription drugs, and herbal and dietary supplements. Diagnosis requires careful review of medications taken, and serological testing for possible viral exposure. Because of its rarity, acute liver failure has not been studied in large, randomised trials, and most treatment recommendations represent expert opinion. Improvements in management have resulted in lower mortality, although liver transplantation, used in nearly 30% of patients with acute liver failure, still provides a life-saving alternative to medical management.

Acute-on-chronic liver failure (ACLF) is a syndrome characterised by acute decompensation of chronic liver disease associated with organ failures and high short-term mortality. Alcohol and chronic viral hepatitis are the most common underlying liver diseases. Up to 40%–50% of the cases of ACLF have no identifiable trigger; in the remaining patients, sepsis, active alcoholism and relapse of chronic viral hepatitis are the most common reported precipitating factors. An excessive systemic inflammatory response seems to play a crucial role in the development of ACLF. Using a liver-adapted sequential organ assessment failure score, it is possible to triage and prognosticate the outcome of patients with ACLF. The course of ACLF is dynamic and changes over the course of hospital admission. Most of the patients will have a clear prognosis between day 3 and 7 of hospital admission and clinical decisions such as evaluation for liver transplant or discussion over goals of care could be tailored using clinical scores. Bioartificial liver support systems, granulocyte-colony stimulating factors or stem-cell transplant are in the horizon of medical care of this patient population; however, data are too premature to implement them as standard of care.

Acetaminophen (APAP) overdose is a common cause of drug-induced acute liver failure. Although hepatocyte cell death is considered to be the critical event in APAP-induced hepatotoxicity, the underlying mechanism remains unclear. Ferroptosis is a newly discovered type of cell death that is caused by a loss of cellular redox homeostasis. As glutathione (GSH) depletion triggers APAP-induced hepatotoxicity, we investigated the role of ferroptosis in a murine model of APAP-induced acute liver failure. APAP-induced hepatotoxicity (evaluated in terms of ALT, AST, and the histopathological score), lipid peroxidation (4-HNE and MDA), and upregulation of the ferroptosis maker PTGS2 mRNA were markedly prevented by the ferroptosis-specific inhibitor ferrostatin-1 (Fer-1). Fer-1 treatment also completely prevented mortality induced by high-dose APAP. Similarly, APAP-induced hepatotoxicity and lipid peroxidation were prevented by the iron chelator deferoxamine. Using mass spectrometry, we found that lipid peroxides derived from n-6 fatty acids, mainly arachidonic acid, were elevated by APAP, and that auto-oxidation is the predominant mechanism of APAP-derived lipid oxidation. APAP-induced hepatotoxicity was also prevented by genetic inhibition of acyl-CoA synthetase long-chain family member 4 or α-tocopherol supplementation. We found that ferroptosis is responsible for APAP-induced hepatocyte cell death. Our findings provide new insights into the mechanism of APAP-induced hepatotoxicity and suggest that ferroptosis is a potential therapeutic target for APAP-induced acute liver failure.

Citrate has been proposed as anticoagulation of choice in continuous renal replacement therapy (CRRT). However, little is known about the pharmacokinetics (PK) and metabolism of citrate in liver failure patients who require CRRT with regional citrate anticoagulation (RCA). This prospective clinical PK study was conducted at King Chulalongkorn Memorial Hospital between July 2019 to April 2021, evaluating seven acute liver failure (ALF) and seven acute-on-chronic liver failure (ACLF) patients who received CRRT support utilizing RCA as an anticoagulant at a citrate dose of 3 mmol/L. For evaluation of the citrate PK, we delivered citrate for 120 min and then stopped for a further 120 min. Total body clearance of citrate was 152.5 ± 50.9 and 195.6 ± 174.3 mL/min in ALF and ACLF, respectively. The ionized calcium, ionized magnesium, and pH slightly decreased after starting citrate infusion and gradually increased to baseline after stopping citrate infusion. Two of the ACLF patients displayed citrate toxicity during citrate infusion, while, no ALF patient had citrate toxicity. In summary, citrate clearance was significantly decreased in critically ill ALF and ACLF patients receiving CRRT. Citrate use as an anticoagulation in these patients is of concern for the risk of citrate toxicity.

Background/Aims: Acute liver failure (ALF) is a rare but severe medical emergency. To date, there is no established treatment for non-acetaminophen-induced acute liver failure (NAI-ALF) other than liver transplantation, and little is known about the use of N-acetylcysteine (NAC) in NAI-ALF. A randomized case control study was conducted with the aim to determine the effect of NAC on the mortality of NAI-ALF patients, as well as to evaluate the safety and efficacy of NAC use. Patients and Methods: A total of 80 patients diagnosed with NAI-ALF were included in the study. Forty patients received NAC infusion for 72 h whereas the control group received placebo. The variables evaluated were demographic characteristics, signs and symptoms, biochemical parameters, and clinical course during hospitalization. Results: The two groups (NAC and control) were comparable for various baseline characteristics (such as etiology of ALF, INR, alanine aminotransferase, creatinine, albumin, and grade of encephalopathy), except for age. Although majority of patients had undetermined etiology (32.5% in NAC group and 42.5% in control group), the second main cause was acute hepatitis E and drug or toxin-induced ALF. The mortality decreased to 28% with the use of NAC versus 53% in the control group (P = 0.023). The use of NAC was associated with shorter length of hospital stay in survived patients (P = 0.002). Moreover, the survival of patients was improved by NAC (P = 0.025). Also, drug-induced ALF showed improved outcome compared to other etiologies. Conclusion: The findings of the study recommend the use of NAC along with conventional treatments in patients with NAI-ALF in non-transplant centers while awaiting referrals and conclude the use of NAC as safe.

There is a lack of scoring system to predict the occurrence of cirrhosis in individuals with acute-on-chronic liver failure (ACLF) in the absence of cirrhosis. The goal of this study was to develop a psoas muscle index (PMI)-based nomogram for cirrhosis risk in non-cirrhotic patients with HBV-related ACLF. We included 274 non-cirrhotic HBV-ACLF patients who were randomly assigned to training and validation groups. Logistic analyses were performed to identify risk factors for cirrhosis. A nomogram was then constructed. The predictive performance of the nomogram was assessed using the area under the receiver operating characteristic curve (AUROC), calibration curve, and decision curve analysis (DCA). During the 360-day follow-up, 44.5% (122/274) of non-cirrhotic HBV-ACLF patients developed cirrhosis. A higher PMI at the L3 level was correlated with a decreased risk of long-term cirrhosis occurrence (OR 0.677, 95% CI 0.518–0.885, P = 0.004). The nomogram incorporating PMI, age, neutrophil-to-lymphocyte ratio (NLR), and international normalized ratio (INR), indicated satisfactory predictive performance for cirrhosis risk stratification in ACLF population. The nomograms had an AUROC of 0.812 (95% CI 0.747–0.866) and 0.824 (95% CI 0.730–0.896) in the training and validation cohorts, respectively. The calibration curves displayed excellent predictive accuracy of the nomogram in both sets. In both cohorts, the DCA verified the nomogram's clinical efficacy. In non-cirrhotic HBV-ACLF patients, a greater PMI appears to protect against long-term cirrhosis occurrence. Strong predictive performance has been demonstrated by PMI-based nomograms in assessing the likelihood of 1-year cirrhosis in those with HBV-ACLF.