Acute liver failure histopathology: A 5-year retrospective study

BACKGROUND

Acute liver failure (ALF) is a rare, life-threatening disease of diverse etiology. It is defined as severe acute liver injury for fewer than 26 weeks' duration with encephalopathy and impaired synthetic function (international normalized ratio [INR] of 1.5 or higher) in a patient without cirrhosis or pre-existing liver disease. The diagnosis rests mainly on the clinical ground with wide range of pathological features. The present study seeks to explore the diverse histological patterns observed in cases for ALF and assess their usefulness in determining the underlying causes for the condition.

METHODOLOGY

A retrospective cross-sectional study was conducted among patients of ALF who underwent liver transplant and transjugular liver biopsy over a five-year period. From 1082 explant liver and 2446 liver biopsies, 22 cases of ALF (10 explants and 12 liver biopsies) were included in the study. Clinical and laboratory details were retrieved and histological findings were reviewed.

RESULT

Age ranged from 10 to 72 years (mean age, 40 years). There was a female predominance with a male:female ratio of 1:1.7. The commonest cause for ALF was virus-induced hepatocellular damage in 36.3% (eight patients), followed by autoimmune hepatitis in 22.7% (five patients), drug-induced liver injury (DILI) in 18.1% (four patients), cryptogenic in 13.6% (three patients) and ischemic injury secondary to large vein thrombosis in 9.0% (two) patients. The histological patterns identified were categorized into six categories. A more comprehensive morphological evaluation was conducted specifically for cases of ALF associated with autoimmune hepatitis (AIH) and compared with other cases of ALF.

CONCLUSION

In summary, our present study illustrates a morphological overlap in various patterns for the purpose of etiological assessment. In cases of AIH ALF, the presence of portal plasma cell infiltrate and central perivenulitis were identified as significant histological features to guide diagnosis.

Alleviation of acetaminophen-induced liver failure using silibinin nanoliposomes: An in vivo study

BACKGROUND

Acetaminophen (Act) overdose is a known inducer of liver failure in both children and adults. Cell annihilation ensues following acetaminophen overdose and its toxic metabolites by depleting cellular GSH storage and increasing ROS levels. Silymarin extract and its major compound silibinin (SLB) possess robust antioxidant properties by inducing ROS elimination; however, low bioavailability and rapid metabolism limit their applications. Herein, we aimed at using SLB liposomes to combat acetaminophen-induced acute liver toxicity.

METHODS

We have developed a SLB-lipid complex to improve SLB loading efficiency within nanoliposome by using the lipid film method. Liposomes were characterized by using DLS and TEM analysis, and the release pattern, and toxicity profile on the normal cells as well as histopathological and serum analysis were investigated to reveal relevant enzyme activities in an animal model.

RESULTS

Data demonstrated that negatively-charged SLB liposomes of 115 nm had homogeneous spherical morphology, and entrapped a considerable quantity of SLB of almost 40%. Liposomes shows a favorable release pattern and were not toxic against NIH3T3 mouse fibroblast cells. The animal study revealed that treatment of mice with SLB nanoliposomes could significantly preserve liver function as revealed by the reduced levels of ALT and AST hepatic enzymes as well as ALP in the serum. Our data indicated that intraperitoneal administration of SLB Lip could significantly reduce ALT enzyme levels (p < 0.05) compared to N-acetylcysteine, while i.v administration resulted in no significant difference compared to control animals with no treatment.

CONCLUSION

The results of this study support the significant hepatoprotective effect of SLB nanoliposomes against acetaminophen-induced toxicity depending on the route of administration.

Effect of a pharmacist-based toxicology consult service on appropriate use of intravenous N-acetylcysteine for acetaminophen toxicity: A retrospective cohort study

Background

Incorporating clinical pharmacists on the medical team has been associated with fewer medication errors and increased error interception. Due to the logistical complexities of the intravenous (IV) N-acetylcysteine (NAC) regimen for acetaminophen toxicity, many opportunities for medication errors exist. A pharmacist-based toxicology consultation service was implemented at our institution, allowing pharmacists to formally aid in the management of toxicology patients throughout their hospital admission, including those with acetaminophen toxicity. The purpose of this study was to evaluate the effect of a house-wide pharmacist-based toxicology consult service on errors associated with IV NAC treatment for patients admitted with acetaminophen toxicity.

Methods

A retrospective, pre-post cohort study was conducted on patients who received IV NAC for acetaminophen toxicity. The intervention evaluated was the implementation of a pharmacist-based toxicology consult service, known as the pharmacy toxicology team. The primary end point was the incidence of an error associated with IV NAC. An error was defined as the composite of inappropriate dose, administration rate, initiation, continuation, or discontinuation.

Results

Eighty-four patients were included; 30 patients in the pregroup, and 54 patients in the postgroup. Fewer patients experienced an error in the postgroup compared to the pregroup (30% vs 63%, P = 0.003).

Conclusion

The implementation of this unique pharmacist-based toxicology consult service was associated with fewer patients experiencing an error related to IV NAC therapy for acetaminophen toxicity. Application of this data may aid in the justification for development of clinical pharmacist-based toxicology consult services at other institutions.

Patterns of transaminase elevation in rhabdomyolysis versus acetaminophen toxicity

BACKGROUND

Transaminase elevations can occur from liver injury or in the setting of rhabdomyolysis. The goal of this study is to evaluate indices that could differentiate acetaminophen toxicity from muscle injury in the setting of transaminase elevations.

METHODS

A retrospective chart review of consecutive cases reported to our regional poison center. Patients with transaminase (AST and ALT) elevation were grouped as those with acetaminophen exposure (AT) and those with elevated creatine phosphokinase (CPK) without evidence of acetaminophen exposure (RHB).

RESULTS

Of the 345 patients included in the study, elevated AST/ALT levels were attributed to rhabdomyolysis in 168 patients and attributed to acetaminophen toxicity in 177 patients. The median AST: ALT values also differed between groups, with patients in the RHB group had higher median ratios (p < 0.001). Using an AST: ALT value of 2.02 as a diagnostic cutoff produced a specificity of 0.52 (95% CI: 0.37, 0.64) and sensitivity of 0.84 (95% CI: 0.73, 0.94) for acetaminophen detection in the test dataset (N = 104).

CONCLUSIONS

Elevated transaminases due to liver injury from acetaminophen ingestion had a different pattern than elevated transaminases due to rhabdomyolysis. Lower AST:ALT ratios were found in acetaminophen cases, however, the specificity using a ratio threshold of ≤1 would be 83%.

The Effect of 4-Methylpyrazole on Oxidative Metabolism of Acetaminophen in Human Volunteers

INTRODUCTION

Acetaminophen (APAP) is commonly ingested in both accidental and suicidal overdose. Oxidative metabolism by cytochrome P450 2E1 (CYP2E1) produces the hepatotoxic metabolite, N-acetyl-p-benzoquinone imine. CYP2E1 inhibition using 4-methylpyrazole (4-MP) has been shown to prevent APAP-induced liver injury in mice and human hepatocytes. This study was conducted to assess the effect of 4-MP on APAP metabolism in humans.

METHODS

This crossover trial examined the ability of 4-MP to inhibit CYP2E1 metabolism of APAP in five human volunteers. Participants received a single oral dose of APAP 80 mg/kg, both with and without intravenous 4-MP, after which urinary and plasma oxidative APAP metabolites were measured. The primary outcome was the fraction of ingested APAP excreted as total oxidative metabolites (APAP-CYS, APAP-NAC, APAP-GSH).

RESULTS

Compared with APAP alone, co-treatment with 4-MP decreased the percentage of ingested APAP recovered as oxidative metabolites in 24-hour urine from 4.48 to 0.51% (95% CI = 2.31-5.63%, p = 0.003). Plasma concentrations of these oxidative metabolites also decreased.

CONCLUSIONS

These results show 4-MP effectively reduced oxidative metabolism of APAP in human volunteers ingesting a supratherapeutic APAP dose.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03878693.

The Clinical Spectrum and Manifestations of Acute Liver Failure

Acute liver failure (ALF) is a rare life-threatening condition characterized by rapid progression and death. Causes vary according to geographic region, with acetaminophen and drug-induced ALF being the most common causes in the United States. Determining the cause aids in predicting the prognosis and the presentation of manifestations and guides providers to perform cause-specific management. At initial presentation, nonspecific symptoms are present but may progress to complications, including cerebral edema, infection, coagulopathy, renal failure, cardiopulmonary failure, and acid-base and/or metabolic disturbances. Although some cases of ALF resolve with conservative measures, liver transplantation is the ultimate treatment in many cases.

Management of Acute Liver Failure in the Intensive Care Unit Setting

This article discusses the intensive care unit management of patients with acute liver failure. It focuses on the clinical presentation, identification, and management of the myriad of complications seen in patients with acute liver failure.

NBAS mutations cause acute liver failure: when acetaminophen is not a culprit

Background

Pediatric acute-liver-failure due to acetaminophen (APAP) administration at therapeutic dosage is rare, while viral infections and metabolic defects are the prevalent causes. Yet, as acetaminophen is routinely used in febrile illnesses, it may be mistakenly held responsible for the acute liver damage.

Case presentation

An 11 month old boy had been on acetaminophen for 10 days (total dose 720 mg = 72 mg/kg) when he developed acute-liver-failure with encephalopathy. As he rapidly improved on N-acetylcysteine (NAC) infusion, it was concluded that chronic acetaminophen administration in an infant had lead to acute-liver-failure even at therapeutic doses, that N-acetylcysteine infusion had been life-saving and should be immediately started in similar circumstances. The child, however, had two further episodes of acute liver damage over a 34-month period, without having been given acetaminophen, as the parents carefully avoided using it. His clinical, laboratory and radiological findings between the acute episodes were unremarkable. His features and skeletal surveys were not suggestive of a syndromic condition. He then went on to suffer another episode of acute-liver-failure with multi-organ failure, necessitating an urgent liver transplant. All efforts to come to a diagnosis for the causes of his recurrent episodes of liver failure had been unsuccessful, until a biallelic mutation in the NBAS gene was reported to be associated with recurrent acute-liver-failure in children. The boy’s DNA analysis revealed compound heterozygous pathogenic mutations in the NBAS gene. Liver failure episodes in these patients are triggered and worsened by fever, most likely due to thermal susceptibility of hepatocytes, hence APAP, rather than being a culprit, is part of the supportive treatment.

Conclusions

We suggest that, in acute-liver-failure with a history of acetaminophen exposure at therapeutic dosage, clinicians should not be contented with administering NAC, but should consider an alternative etiology, above all if the episodes are recurrent, and actively start supportive and antipyretic treatment while seeking the advice of a specialist unit.

Drug-induced liver injury: Do we know everything?

Interest in drug-induced liver injury (DILI) has dramatically increased over the past decade, and it has become a hot topic for clinicians, academics, pharmaceutical companies and regulatory bodies. By investigating the current state of the art, the latest scientific findings, controversies, and guidelines, this review will attempt to answer the question: Do we know everything? Since the first descriptions of hepatotoxicity over 70 years ago, more than 1000 drugs have been identified to date, however, much of our knowledge of diagnostic and pathophysiologic principles remains unchanged. Clinically ranging from asymptomatic transaminitis and acute or chronic hepatitis, to acute liver failure, DILI remains a leading causes of emergent liver transplant. The consumption of unregulated herbal and dietary supplements has introduced new challenges in epidemiological assessment and clinician management. As such, numerous registries have been created, including the United States Drug-Induced Liver Injury Network, to further our understanding of all aspects of DILI. The launch of LiverTox and other online hepatotoxicity resources has increased our awareness of DILI. In 2013, the first guidelines for the diagnosis and management of DILI, were offered by the Practice Parameters Committee of the American College of Gastroenterology, and along with the identification of risk factors and predictors of injury, novel mechanisms of injury, refined causality assessment tools, and targeted treatment options have come to define the current state of the art, however, gaps in our knowledge still undoubtedly remain.

Acetaminophen-Induced Hepatotoxicity: a Comprehensive Update

Hepatic injury and subsequent hepatic failure due to both intentional and non-intentional overdose of acetaminophen (APAP) has affected patients for decades, and involves the cornerstone metabolic pathways which take place in the microsomes within hepatocytes. APAP hepatotoxicity remains a global issue; in the United States, in particular, it accounts for more than 50% of overdose-related acute liver failure and approximately 20% of the liver transplant cases. The pathophysiology, disease course and management of acute liver failure secondary to APAP toxicity remain to be precisely elucidated, and adverse patient outcomes with increased morbidity and mortality continue to occur. Although APAP hepatotoxicity follows a predictable timeline of hepatic failure, its clinical presentation might vary. N-acetylcysteine (NAC) therapy is considered as the mainstay therapy, but liver transplantation might represent a life-saving procedure for selected patients. Future research focus in this field may benefit from shifting towards obtaining antidotal knowledge at the molecular level, with focus on the underlying molecular signaling pathways.

The acetaminophen metabolite N-acetyl-p-benzoquinone imine (NAPQI) inhibits glutathione synthetase in vitro; a clue to the mechanism of 5-oxoprolinuric acidosis?

1. Metabolic acidosis due to accumulation of l-5-oxoproline is a rare, poorly understood, disorder associated with acetaminophen treatment in malnourished patients with chronic morbidity. l-5-Oxoprolinuria signals abnormal functioning of the γ-glutamyl cycle, which recycles and synthesises glutathione. Inhibition of glutathione synthetase (GS) by N-acetyl-p-benzoquinone imine (NAPQI) could contribute to 5-oxoprolinuric acidosis in such patients. We investigated the interaction of NAPQI with GS in vitro. 2. Peptide mapping of co-incubated NAPQI and GS using mass spectrometry demonstrated binding of NAPQI with cysteine-422 of GS, which is known to be essential for GS activity. Computational docking shows that NAPQI is properly positioned for covalent bonding with cysteine-422 via Michael addition and hence supports adduct formation. 3. Co-incubation of 0.77 μM of GS with NAPQI (25-400 μM) decreased enzyme activity by 16-89%. Inhibition correlated strongly with the concentration of NAPQI and was irreversible. 4. NAPQI binds covalently to GS causing irreversible enzyme inhibition in vitro. This is an important novel biochemical observation. It is the first indication that NAPQI may inhibit glutathione synthesis, which is pivotal in NAPQI detoxification. Further studies are required to investigate its biological significance and its role in 5-oxoprolinuric acidosis.

The protective effects of carvacrol and thymol against paracetamol-induced toxicity on human hepatocellular carcinoma cell lines (HepG2)

Acetaminophen (APAP) overdose could induce liver damage and lead to acute liver failure. The treatment of APAP overdoses could be improved by new therapeutic strategies. Thymus spp., which has many beneficial effects and has been used in folk medicine, is one such potential strategy. In the present study, the hepatoprotective activity of the main constituents of Thymus spp., carvacrol and thymol, were evaluated in light of APAP-induced hepatotoxicity. We hoped to understand the hepatoprotective mechanism of these agents on the antioxidant system and pro-inflammatory cytokines in vitro. Dose-dependent effects of thymol and carvacrol (25, 50, and 100 µM) were tested on cultured HepG2 cells. N-Acetylcysteine (NAC) was tested as positive control. We showed that APAP inhibited HepG2 cell growth by inducing inflammation and oxidative stress. Incubating APAP-exposed HepG2 cells with carvacrol and thymol for 24 h ameliorated this inflammation and oxidative stress. We also evaluated alanine transaminase and lactate dehydrogenase levels of HepG2 cells. We found that thymol and carvacrol protected against APAP-induced toxicity in HepG2 cells by increasing antioxidant activity and reducing pro-inflammatory cytokines, such as tumor necrosis factor α and interleukin 1β. Taking together high-dose thymol and carvacrol treatment has an effect close to NAC treatment in APAP toxicity, but thymol has better treatment effect than carvacrol.

An Update on Treatment of Drug-Induced Liver Injury

Drug-induced liver injury (DILI) has been linked to more than 1,000 medications and remains the most common cause of acute liver failure in the United States. Here, we review the most current literature regarding treatment and make recommendations for the management of this relatively common disease. Since treatment of DILI remains largely elusive, recent studies have attempted to define new management strategies for these difficult patients. Early diagnosis and withdrawal of the suspected medication is the mainstay of treatment of DILI. For acetaminophen and Amanita mushroom poisoning, there are specific therapies in use. Finally, there are other possible management modalities for DILI, including corticosteroids and ursodeoxycholic acid.

Glutathione metabolism modeling: a mechanism for liver drug-robustness and a new biomarker strategy

BACKGROUND

Glutathione metabolism can determine an individual's ability to detoxify drugs. To increase understanding of the dynamics of cellular glutathione homeostasis, we have developed an experiment-based mathematical model of the kinetics of the glutathione network. This model was used to simulate perturbations observed when human liver derived THLE cells, transfected with human cytochrome P452E1 (THLE-2E1 cells), were exposed to paracetamol (acetaminophen).

METHODS

Human liver derived cells containing extra human cytochrome P4502E1 were treated with paracetamol at various levels of methionine and in the presence and absence of an inhibitor of glutamyl-cysteine synthetase (GCS). GCS activity was also measured in extracts. Intracellular and extracellular concentrations of substances involved in glutathione metabolism were measured as was damage to mitochondria and proteins. A bottom up mathematical model was made of the metabolic pathways around and including glutathione.

RESULTS

Our initial model described some, but not all the metabolite-concentration and flux data obtained when THLE-2E1 cells were exposed to paracetamol at concentrations high enough to affect glutathione metabolism. We hypothesized that the lack of correspondence could be due to upregulation of expression of glutamyl cysteine synthetase, one of the enzymes controlling glutathione synthesis, and confirmed this experimentally. A modified model which incorporated this adaptive response adequately described the observed changes in the glutathione pathway. Use of the adaptive model to analyze the functioning of the glutathione network revealed that a threshold input concentration of methionine may be required for effective detoxification of reactive metabolites by glutathione conjugation. The analysis also provided evidence that 5-oxoproline and ophthalmic acid are more useful biomarkers of glutathione status when analyzed together than when analyzed in isolation, especially in a new, model-assisted integrated biomarker strategy.

CONCLUSION

A robust mathematical model of the dynamics of cellular changes in glutathione homeostasis in cells has been developed and tested in vitro.

GENERAL SIGNIFICANCE

Mathematical models of the glutathione pathway that help examine mechanisms of cellular protection against xenobiotic toxicity and the monitoring thereof, can now be made.

Efficacy of free glutathione and niosomal glutathione in the treatment of acetaminophen-induced hepatotoxicity in cats

Acetaminophen (APAP) administration results in hepatotoxicity and hematotoxicity in cats. The response to three different treatments against APAP poisoning was evaluated. Free glutathione (GSH) (200mg/kg), niosomal GSH (14 mg/kg) and free amino acids (180 mg/kg of N-acetylcysteine and 280 mg/kg of methionine) were administered to cats that were intoxicated with APAP (a single dose of 150 mg/kg, p.o.). Serum concentration of alanine aminotransferase (ALT) along with serum, liver and erythrocyte concentration of GSH and methemoglobin percentage were measured before and 4, 24 and 72 hours after APAP administration. Free GSH (200 mg/kg) and niosomal GSH (14 mg/kg) were effective in reducing hepatotoxicity and hematotoxicity in cats intoxicated with a dose of 150 mg/kg APAP. We conclude that both types of treatments can protect the liver and haemoglobin against oxidative stress in APAP intoxicated cats. Furthermore, our results showed that treatment with niosomal GSH represents an effective therapeutic approach for APAP poisoning.

Acute liver failure complicating jejunojejunal intussusception presentation in a gastric bypass patient

Over 200 000 weight loss procedures are performed annually in the United States. Physicians must therefore be cognizant of the unique array of complications associated with these procedures. We describe a case of jejunojejunal intussusception in a gastric bypass patient who presented with acute liver failure (ALF) due to acetaminophen (APAP) toxicity. Our patient is a 29 year-old female who had undergone Roux-en-Y gastric bypass surgery seven years prior. She was evaluated in the emergency department for confusion. Her family reported a 3-wk history of progressive abdominal pain and vomiting, for which she had ingested 40 acetaminophen/oxycodone tablets over the past 2 d. Physical examination showed icteric sclerae, a distended abdomen, and grade I encephalopathy. She fulfilled the criteria for ALF and was listed for liver transplantation. Abdominal computed tomography scan revealed a jejunojejunal intussusception. She underwent emergent exploratory laparotomy and resection of the infarcted intussusceptum and the previous jejunojejunostomy. She had rapid clinical improvement, with decreasing liver enzymes and improved hepatic synthetic function. She had complete resolution of coagulopathy and encephalopathy, and was removed from the liver transplant list. She was discharged home 20 d after hospitalization with normal liver tests. This case demonstrates that acute abdominal catastrophes can potentiate liver injury in the setting of acetaminophen toxicity. Encephalopathy may obscure history and physical exam findings. This case also exemplifies the pitfalls in the management of the bariatric surgery patient and the importance of multispecialty collaboration in patients presenting with organ failure.