An optimized short-term steroid therapy for chronic drug-induced liver injury: A prospective randomized clinical trial.

BACKGROUND AND AIMS: The use of corticosteroids in chronic drug-induced liver injury (DILI) is an important issue. Our previous randomized controlled trial showed that patients with chronic DILI benefited from a 48-week steroid stepwise reduction (SSR) regimen. However, it remains unclear whether a shorter course of therapy can achieve similar efficacy. In this study, we aimed to assess whether a 36-week SSR can achieve efficacy similar to that of 48-week SSR. METHODS: A randomized open-label trial was performed. Eligible patients were randomly assigned to the 36- or 48-week (1:1) SSR group. Liver biopsies were performed at baseline and at the end of treatment. The primary outcome was the proportion of patients with relapse rate (RR). The secondary outcomes were improvement in liver histology and safety. RESULTS: Of the 90 participants enrolled, 84 (87.5%) completed the trial, and 62 patients (68.9%) were women. Hepatocellular damage was observed in 53.4% of the cohort. The RR was 7.1% in the 36-week SSR group but 4.8% in the 48-week SSR group, as determined by per-protocol set analysis (p = 1.000). Significant histological improvements in histological activity (93.1% vs. 92.9%, p = 1.000) and fibrosis (41.4% vs. 46.4%, p = .701) were observed in both the groups. Biochemical normalization time did not differ between the two groups. No severe adverse events were observed. CONCLUSIONS: Both the 36- and 48-week SSR regimens demonstrated similar biochemical response and histological improvements with good safety, supporting 36-week SSR as a preferable therapeutic choice (ClinicalTrials.gov, NCT03266146).

Immune Checkpoint Inhibitor-Induced Liver Injury.

In recent years cancer treatment has been revolutionized by the development and wide application of checkpoint inhibitor (CPI) drugs, which are a form of immunotherapy. CPI treatment is associated with immune-related adverse events, off-target tissue destructive inflammatory complications, which may affect a range of organs, with liver inflammation (hepatitis) being one of the more commonly noted events. This is a novel form of drug-induced liver injury and a rapidly evolving field, as our understanding of both the basic immunopathology of CPI hepatitis (CPI-H) and optimal clinical management, races to catch up with the increasing application of this form of immunotherapy in clinical practice. In this review, we summarize current evidence and understanding of CPI-H, from fundamental immunology to practical patient management.

Prediction of biochemical nonresolution in patients with chronic drug-induced liver injury: A large multicenter study.

BACKGROUND AND AIMS: To clarify high-risk factors and develop a nomogram model to predict biochemical resolution or biochemical nonresolution (BNR) in patients with chronic DILI. APPROACH AND RESULTS: Retrospectively, 3655 of 5326 patients with chronic DILI were enrolled from nine participating hospitals, of whom 2866 underwent liver biopsy. All of these patients were followed up for over 1 year and their clinical characteristics were retrieved from electronic medical records. The endpoint was BNR, defined as alanine aminotransferase or aspartate aminotransferase >1.5× upper limit of normal or alkaline phosphatase >1.1× ULN, at 12 months from chronic DILI diagnosis. The noninvasive high-risk factors for BNR identified by multivariable logistic regression were used to establish a nomogram, which was validated in an independent external cohort. Finally, 19.3% (707 of 3655) patients presented with BNR. Histologically, with the increase in liver inflammation grades and fibrosis stages, the proportion of BNR significantly increased. The risk of BNR was increased by 21.3-fold in patients with significant inflammation compared to none or mild inflammation (p < 0.001). Biochemically, aspartate aminotransferase and total bilirubin, platelets, prothrombin time, sex, and age were associated with BNR and incorporated to construct a nomogram model (BNR-6) with a concordance index of 0.824 (95% CI, 0.798-0.849), which was highly consistent with liver histology. These results were successfully validated both in the internal cohort and external cohort. CONCLUSIONS: Significant liver inflammation is a robust predictor associated with biochemical nonresolution. The established BNR-6 model provides an easy-to-use approach to assess the outcome of chronic DILI.

Aging exaggerates acute-on-chronic alcohol-induced liver injury in mice and humans by inhibiting neutrophilic sirtuin 1-C/EBPα-miRNA-223 axis.

BACKGROUND AND AIMS: Aging exacerbates liver neutrophil infiltration and alcohol-associated liver disease (ALD) in mice and humans, but the underlying mechanisms remain obscure. This study aimed to examine the effect of aging and alcohol consumption on neutrophilic Sirtuin 1 (SIRT1) and microRNA-223 (miR-223), and their contribution to ALD pathogeneses. APPROACH AND RESULTS: Young and aged myeloid-specific Sirt1 knockout mice were subjected to chronic-plus-binge ethanol feeding. Blood samples from healthy controls and patients with chronic alcohol drinking who presented with acute intoxication were analyzed. Neutrophilic Sirt1 and miR-223 expression were down-regulated in aged mice compared with young mice. Deletion of the Sirt1 gene in myeloid cells including neutrophils exacerbated chronic-plus-binge ethanol-induced liver injury and inflammation and down-regulated neutrophilic miR-223 expression. Immunoprecipitation experiments revealed that SIRT1 promoted C/EBPα deacetylation by directly interacting with C/EBPα, a key transcription factor that controls miR-223 biogenesis, and subsequently elevated miR-223 expression in neutrophils. Importantly, down-regulation of SIRT1 and miR-223 expression was also observed in circulating neutrophils from middle-aged and elderly subjects compared with those from young individuals. Chronic alcohol users with acute intoxication had a reduction in neutrophilic SIRT1 expression in young and middle-aged patients, with a greater reduction in the latter group. The neutrophilic SIRT1 expression correlated with neutrophilic miR-223 and serum alanine transaminase levels in those patients. CONCLUSIONS: Aging increases the susceptibility of alcohol-induced liver injury in mice and humans through the down-regulation of the neutrophilic SIRT1-C/EBPα-miR-223 axis, which could be a therapeutic target for the prevention and/or treatment of ALD.

Role of Mechanistic Target of Rapamycin and Autophagy in Alcohol-Induced Adipose Atrophy and Liver Injury.

Chronic alcohol consumption induces adipose tissue atrophy. However, the mechanisms for how alcohol induces lipodystrophy and its impact on liver steatosis and injury are not fully elucidated. Autophagy is a highly conserved lysosomal degradation pathway, which regulates cellular homeostasis. Mice with autophagy deficiency in adipose tissue have impaired adipogenesis. However, whether autophagy plays a role in alcohol-induced adipose atrophy and how altered adipocyte autophagy contributes to alcohol-induced liver injury remain unclear. To determine the role of adipose autophagy and mechanistic target of rapamycin (mTOR) in alcohol-induced adipose and liver pathogenesis, we generated adipocyte-specific Atg5 knockout (KO), adipocyte-specific mTOR KO, adipocyte-specific Raptor KO, and adipocyte-specific tuberous sclerosis complex 1 KO mice by crossing floxed mice with Adipoq-Cre. The KO mice and their matched wild-type mice were challenged with chronic-plus-binge alcohol mouse model. Chronic-plus-binge alcohol induced adipose atrophy with increased autophagy and decreased Akt/mTOR signaling in epididymal adipose tissue in wild-type mice. Adipocyte-specific Raptor KO mice experienced exacerbated alcohol-induced steatosis, but neither adipocyte-specific mTOR nor adipocyte-specific tuberous sclerosis complex 1 KO mice exhibited similar detrimental effects. Adipocyte-specific Atg5 KO mice had increased circulating levels of fibroblast growth factor 21 and adiponectin and were resistant to alcohol-induced adipose atrophy and liver injury. In conclusion, autophagy deficiency in adipose tissue leads to reduced sensitivity to alcohol-induced adipose atrophy, which ameliorates alcohol-induced liver injury in mice.

Profile of herbal and dietary supplements induced liver injury in Latin America: A systematic review of published reports.

Hepatotoxicity related to HDS is a growing global health issue. We have undertaken a systematic review of published case reports and case series from LA from 1976 to 2020 to describe the clinical features of HDS related hepatotoxicity in this region. We search in PubMed, Web of Science, Scopus and specific LA databases according to PRISMA guidelines. Only HILI cases published in LA that met criteria for DILI definition were included. Duplicate records or reports that lacked relevant data that precluded establishing causality were excluded. Finally, 17 records (23 cases) were included in this review. Centella asiatica, Carthamus tinctorius, and Herbalife® were the most reported HDS culprit products, the main reason for HDS consumption was weight loss. The clinical characteristics of HDS hepatotoxicity in our study were compared to those of other studies in the USA, Europe and China showing a similar signature with predominance of young females, hepatocellular damage, a high rate of ALF and mortality, more frequent inadvertent re-challenge and chronic damage. This study underscores the challenge in causality assessment when multi-ingredients HDS are taken and the need for consistent publication practice when reporting hepatotoxicity cases due to HDS, to foster HDS liver safety particularly in LA.

Effect of carvedilol versus propranolol on acute and chronic liver toxicity in rats.

Non-selective ß-blockers have largely been used for prophylaxis of bleeding from gastroesophageal varices, but their hepatic effects and their influence on the development of varices has yet to be clarified. This study examined whether carvedilol would reduce acute and chronic liver injury in rats in comparison to propranolol. Experiment (1) Investigated the effects of carvedilol (1.2 mg/kg) and propranolol (4.0 mg/kg) administered daily for 7 days by gavage on paracetamol (1500 mg/kg i.p.) -induced acute liver injury in rats. Experiment (2) Investigated the effects of carvedilol (1.2 mg/kg) and propranolol (4.0 mg/kg) by gavage daily for 8 weeks on CCl4 -induced chronic liver injury in rats. Biochemical markers and histopathology of the livers were studied. Liver perfusion studies were carried out on CCl4 treated rats. Experiment (1) Carvedilol significantly improved the functional state of the liver in paracetamol-induced acute toxic hepatitis to a greater extent than propranolol. This was evidenced by a greater reduction in elevated serum levels of ALT and AST, hepatic MDA and TNF-α, attenuation of the paracetamol-induced decrease in GSH, together with improvement in the histological architecture of the liver. Experiment (2) Carvedilol was superior to propranolol against CCl4-induced hepatic injury and fibrogenesis. It suppressed hepatic inflammation, attenuated hepatic oxidative stress, and inhibited HSC activation. Carvedilol also decreased portal perfusion pressure. These results suggest that carvedilol might be a therapeutic anti-fibrogenic candidate against hepatic fibrosis, protecting the liver from acute and chronic toxic injury, in addition to lowering portal pressure.

Shh-Yap signaling controls hepatic ductular reactions in CCl4 -induced liver injury.

Carbon tetrachloride (CCl4 ) exposure can induce hepatic ductular reactions. To date, however, the related mechanism remains largely unknown. Sonic hedgehog (Shh) and Yes-associated protein (Yap) signaling are correlated with liver injury and regeneration. Herein, we investigated the role of Shh and Yap signaling in the fate of ductular reaction cells in CCl4 -treated livers and the possible mechanisms. Wild-type and Shh-EGFP-Cre male mice were exposed to CCl4 (2 mL/kg), and then treated with or without the Shh signaling inhibitor Gant61. The level of liver injury, proliferation of ductular reaction cells, and expression levels of mRNA and protein related to the Shh and Yap signaling components were assessed. Results showed that CCl4 treatment induced liver injury and promoted activation and proliferation of ductular reaction cells. In addition, CCl4 induced the expression of Shh ligands in hepatocytes, accompanied by activation of Shh and Yap1 signaling in the liver. Furthermore, administration of Gant61 ameliorated liver regeneration, inhibited hepatic ductular reactions, and decreased Shh and Yap1 signaling activity. Thus, Shh-Yap1 signaling appears to play an integral role in the proliferation of ductular reaction cells in CCl4 -induced liver injury. This study should improve our understanding of the mechanism of CCl4 -induced liver injury and ductular reactions and provide support for future investigations on liver disease therapy.

Acorbine, a Corbicula japonica-derived tripeptide containing non-proteinogenic amino acids, suppresses ethanol-induced liver injury.

Since ancient times, Corbicula extract has been believed in Japan to have hepatoprotective effects, but it remains unclear whether these claims are true, and if so, which component is responsible for hepatoprotection. In this study, we showed that Corbicula extract exerted a protective effect against liver damage. Recent work identified acorbine (ß-alanyl-ornithyl-ornithine), a novel tripeptide containing non-proteinogenic amino acids, in the extract of Corbicula japonica. Synthesized acorbine cured alcohol-induced liver damage in mice. In addition, acorbine purified from Corbicula extract exerted a protective effect against alcohol-induced hepatotoxicity in a culture liver model derived from mouse ES/iPS cells. Thus, acorbine is one of the components of Corbicula extract that protects hepatocytes against ethanol-induced death.

Chronic Hepatotoxicity in Patients with Metastatic Neuroendocrine Tumor: Transarterial Chemoembolization versus Transarterial Radioembolization.

PURPOSE: To compare the manifestations of chronic liver injury following transarterial chemoembolization with those of transarterial radioembolization (TARE) in patients with neuroendocrine tumor (NET). MATERIALS AND METHODS: This study consisted of an Institutional Review Board-approved single-institution retrospective analysis of NET patients who received transarterial chemoembolization from 2006 to 2016 and TARE from 2005 to 2014 and survived at least 1 year from the initial treatment. Patients receiving only transarterial chemoembolization (n = 63) or TARE (n = 28) were evaluated for the presence or absence of durable hepatic toxicities occurring at least 6 months after initial treatment. The definitions and grades of liver injury were adapted from Common Terminology Criteria for Adverse Events version 4.0 and were characterized by the presence of laboratory or clinical toxicities of Grade 3 or above. RESULTS: Chronic hepatic toxicity occurred in 14 of 63 transarterial chemoembolization patients (22%) with a total of 26 Grade 3-4 events, in whom elevation of bilirubin was the most common toxicity, compared to 8 of 28 TARE patients (29%) with a total of 16 Grade 3-4 and 2 Grade 5 events, in whom ascites were the most frequent toxicity. There were more laboratory toxicities in the transarterial chemoembolization group (65% vs 38%, P = .11) and fewer Grade 4-5 injuries (6% vs 27% of patients, P = .06). There was also a significantly higher number of patients who experienced intrahepatic progression of disease in the transarterial chemoembolization cohort than in the TARE patients (75% vs 43%, respectively; P = .005). CONCLUSIONS: Delayed hepatotoxicity from transarterial chemoembolization and TARE occurred in 22% and 29% of patients, respectively, from 6 months to several years following treatment. Transarterial chemoembolization-related toxicities on average were less severe and manifested primarily as laboratory derangements, compared to TARE toxicities which consisted of clinical hepatic decompensation.

Understanding Mechanisms Underlying Non-Alcoholic Fatty Liver Disease (NAFLD) in Mental Illness: Risperidone and Olanzapine Alter the Hepatic Proteomic Signature in Mice.

Patients with severe mental illness have increased mortality, often linked to cardio-metabolic disease. Non-alcoholic fatty liver disease (NAFLD) incidence is higher in patients with schizophrenia and is exacerbated with antipsychotic treatment. NAFLD is associated with obesity and insulin resistance, both of which are induced by several antipsychotic medications. NAFLD is considered an independent risk factor for cardiovascular disease, the leading cause of death for patients with severe mental illness. Although the clinical literature clearly defines increased risk of NAFLD with antipsychotic therapy, the underlying mechanisms are not understood. Given the complexity of the disorder as well as the complex pharmacology associated with atypical antipsychotic (AA) medications, we chose to use a proteomic approach in healthy mice treated with a low dose of risperidone (RIS) or olanzapine (OLAN) for 28 days to determine effects on development of NAFLD and to identify pathways impacted by AA medications, while removing confounding intrinsic effects of mental illness. Both AA drugs caused development of steatosis in comparison with vehicle controls (p < 0.01) and affected multiple pathways relating to energy metabolism, NAFLD, and immune function. AA-associated alteration in autonomic function appears to be a unifying theme in the regulation of hepatic pathology.

Concordance between Thioacetamide-Induced Liver Injury in Rat and Human In Vitro Gene Expression Data.

The immense resources required and the ethical concerns for animal-based toxicological studies have driven the development of in vitro and in silico approaches. Recently, we validated our approach in which the expression of a set of genes is uniquely associated with an organ-injury phenotype (injury module), by using thioacetamide, a known liver toxicant. Here, we sought to explore whether RNA-seq data obtained from human cells (in vitro) treated with thioacetamide-S-oxide (a toxic intermediate metabolite) would correlate across species with the injury responses found in rat cells (in vitro) after exposure to this metabolite as well as in rats exposed to thioacetamide (in vivo). We treated two human cell types with thioacetamide-S-oxide (primary hepatocytes with 0 (vehicle), 0.125 (low dose), or 0.25 (high dose) mM, and renal tubular epithelial cells with 0 (vehicle), 0.25 (low dose), or 1.00 (high dose) mM) and collected RNA-seq data 9 or 24 h after treatment. We found that the liver-injury modules significantly altered in human hepatocytes 24 h after high-dose treatment involved cellular infiltration and bile duct proliferation, which are linked to fibrosis. For high-dose treatments, our modular approach predicted the rat in vivo and in vitro results from human in vitro RNA-seq data with Pearson correlation coefficients of 0.60 and 0.63, respectively, which was not observed for individual genes or KEGG pathways.

Assessment of Serious Acute and Chronic Idiosyncratic Drug-Induced Liver Injury in Clinical Practice.

Drug-induced liver injury (DILI) is the leading cause of acute liver failure (ALF) in developed countries. The extremely variable phenotype of DILI, both in presentation and in severity, is one of the distinctive characteristics of the disease and one of the major challenges that hepatologists face when assessing hepatotoxicity cases. A new Hy's law that more accurately predicts the risk of ALF related to DILI has been proposed and validated. Other prognostic scoring algorithms for the early identification of DILI patients who may go on to develop ALF have been developed as it is of most clinical relevance to stratify patients for closer monitoring. Recent data indicate that acute DILI often presents a more prolonged resolution or evolves into chronicity at a higher frequency than other forms of acute liver injury. Risk factors for chronicity, specific phenotypes, and histological features are discussed in this study. Biomarkers to predict DILI outcome are in need.

Dysregulated Bile Transporters and Impaired Tight Junctions During Chronic Liver Injury in Mice.

BACKGROUND & AIMS: Liver fibrosis, hepatocellular necrosis, inflammation, and proliferation of liver progenitor cells are features of chronic liver injury. Mouse models have been used to study the end-stage pathophysiology of chronic liver injury. However, little is known about differences in the mechanisms of liver injury among different mouse models because of our inability to visualize the progression of liver injury in vivo in mice. We developed a method to visualize bile transport and blood-bile barrier (BBlB) integrity in live mice. METHODS: C57BL/6 mice were fed a choline-deficient, ethionine-supplemented (CDE) diet or a diet containing 0.1% 3,5-diethoxycarbonyl-1, 4-dihydrocollidine (DDC) for up to 4 weeks to induce chronic liver injury. We used quantitative liver intravital microscopy (qLIM) for real-time assessment of bile transport and BBlB integrity in the intact livers of the live mice fed the CDE, DDC, or chow (control) diets. Liver tissues were collected from mice and analyzed by histology, immunohistochemistry, real-time polymerase chain reaction, and immunoblots. RESULTS: Mice with liver injury induced by a CDE or a DDC diet had breaches in the BBlB and impaired bile secretion, observed by qLIM compared with control mice. Impaired bile secretion was associated with reduced expression of several tight-junction proteins (claudins 3, 5, and 7) and bile transporters (NTCP, OATP1, BSEP, ABCG5, and ABCG8). A prolonged (2-week) CDE, but not DDC, diet led to re-expression of tight junction proteins and bile transporters, concomitant with the reestablishment of BBlB integrity and bile secretion. CONCLUSIONS: We used qLIM to study chronic liver injury, induced by a choline-deficient or DDC diet, in mice. Progression of chronic liver injury was accompanied by loss of bile transporters and tight junction proteins.

Apixaban-induced liver injury.

The use of new oral anticoagulants such as apixaban is increasing. We present the case of an 85-year-old patient who was diagnosed with mixed profile toxic hepatitis due to apixaban use. An etiological study was negative, except for anti-smooth muscle antibodies, and a liver biopsy ruled out autoimmune hepatitis. The patient was assigned a score of 7 on the CIOMS/RUCAM scale, indicating a probable causality. The liver injury improved after the withdrawal of apixaban. A previous meta-analysis reported that the risk of hepatotoxicity does not increase with the use of apixaban, nor were any cases reported in registry studies. Nonetheless, more than 120 possible cases currently appear in the European pharmacovigilance database (EudraVigilance). We suggest that apixaban should be considered as a possible cause of liver injury.

Proliferative and Apoptotic Activity of Bone Marrow Monocyte Lineage Cells in the Offspring of Female Rats with Chronic Toxic Liver Injury.

We analyzed proliferative and apoptotic activity of bone marrow monocyte lineage cells in the offspring of mothers with experimental toxic injury to the liver. Rat pups were examined at different times of ontogeny. Inhibition of proliferative activity and increase in apoptotic activity in bone marrow monocyte cells of experimental rat pups in comparison with intact ones were found.

Risk of liver decompensation with cumulative use of mitochondrial toxic nucleoside analogues in HIV/hepatitis C virus coinfection.

PURPOSE: Among patients dually infected with human immunodeficiency virus (HIV) and chronic hepatitis C virus (HCV), use of antiretroviral therapy (ART) containing mitochondrial toxic nucleoside reverse transcriptase inhibitors (mtNRTIs) might induce chronic hepatic injury, which could accelerate HCV-associated liver fibrosis and increase the risk of hepatic decompensation and death. METHODS: We conducted a cohort study among 1747 HIV/HCV patients initiating NRTI-containing ART within the Veterans Aging Cohort Study (2002-2009) to determine if cumulative mtNRTI use increased the risk of hepatic decompensation and death among HIV-/HCV-coinfected patients. Separate marginal structural models were used to estimate hazard ratios (HRs) of each outcome associated with cumulative exposure to ART regimens that contain mtNRTIs versus regimens that contain other NRTIs. RESULTS: Over 7033 person-years, we observed 97 (5.6%) decompensation events (incidence rate, 13.8/1000 person-years) and 125 (7.2%) deaths (incidence rate, 17.8 events/1000 person-years). The risk of hepatic decompensation increased with cumulative mtNRTI use (1-11 mo: HR, 1.79 [95% confidence interval (CI), 0.74-4.31]; 12-35 mo: HR, 1.39 [95% CI, 0.68-2.87]; 36-71 mo: HR, 2.27 [95% CI, 0.92-5.60]; >71 mo: HR, 4.66 [95% CI, 1.04-20.83]; P = .045) versus nonuse. Cumulative mtNRTI use also increased risk of death (1-11 mo: HR, 2.24 [95% CI, 1.04-4.81]; 12-35 mo: HR, 2.05 [95% CI, 0.68-6.20]; 36-71 mo: HR, 3.04 [95% CI, 1.12-8.26]; >71 mo: HR, 3.93 [95% CI, 0.75-20.50]; P = .030). CONCLUSIONS: These findings suggest that cumulative mtNRTI use may increase the risk of hepatic decompensation and death in HIV/HCV coinfection. These drugs should be avoided when alternatives exist for HIV/HCV patients.

Umbilical Cord MSCs Reverse D-Galactose-Induced Hepatic Mitochondrial Dysfunction via Activation of Nrf2/HO-1 Pathway.

Mitochondria are the central hubs for cellular bioenergetics and are crucial to cell survival. It is well accepted that compromised mitochondrial function is linked with hepatocytes injury and contribute to progression of liver diseases. Despite the therapeutic potential of mesenchymal stem cells (MSCs) transplantation on hepatic disorders have been extensively investigated, the effects of MSCs on mitochondrial function in liver injury models remain unknown. Here we investigated the effects of treatment with umbilical cord (UC) MSC in a rat model of D-galactose (D-Gal) induced liver injury, characterized by organ damage, oxidative stress and mitochondrial dysfunction. Our results showed that UC-MSCs treatment significantly alleviated histological lesion and attenuated the elevation of liver biochemical markers, demonstrating its protective effects on D-Gal induced hepatic disorders. Mitochondria isolated from the liver of D-Gal models exhibited decreased antioxidant capacity as well as compromised bioenergetics functions, as shown by a loss of mitochondrial membrane potential, elevation of reactive oxygen species (ROS) production, reduction of mitochondrial respiration complexes and ATP decrement. Treatment of rats with UC-MSCs remarkably blunted these changes and rescued mitochondrial efficiency. Mechanistically, we found that the protective potential of UC-MSCs administration was mediated by nuclear factor-E2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) pathway, but not FOXO3a pathway. In conclusion, the attenuating effects of UC-MSCs on hepatic damage partially rely on normalizing mitochondrial function and preventing a state of energetic deficit via activation of Nrf2/HO-1 pathway.

Carbamoyl phosphate synthetase-1 is a rapid turnover biomarker in mouse and human acute liver injury.

Several serum markers are used to assess hepatocyte damage, but they have limitations related to etiology specificity and prognostication. Identification of novel hepatocyte-specific biomarkers could provide important prognostic information and better pathogenesis classification. We tested the hypothesis that hepatocyte-selective biomarkers are released after subjecting isolated mouse hepatocytes to Fas-ligand-mediated apoptosis. Proteomic analysis of hepatocyte culture medium identified the mitochondrial matrix protein carbamoyl phosphate synthetase-1 (CPS1) among the most readily detected proteins that are released by apoptotic hepatocytes. CPS1 was also detected in mouse serum upon acute challenge with Fas-ligand or acetaminophen and in hepatocytes upon hypoosmotic stress, independent of hepatocyte caspase activation. Furthermore, CPS1 was observed in sera of mice chronically fed the hepatotoxin 3,5-diethoxycarbonyl-1,4-dihydrocollidine. Mouse CPS1 detectability was similar in serum and plasma, and its half-life was 126 ± 9 min. Immune staining showed that CPS1 localized to mouse hepatocytes but not ductal cells. Analysis of a few serum samples from patients with acute liver failure (ALF) due to acetaminophen, Wilson disease, or ischemia showed readily detectable CPS1 that was not observed in several patients with chronic viral hepatitis or in control donors. Notably, CPS1 rapidly decreased to undetectable levels in sera of patients with acetaminophen-related ALF who ultimately recovered, while alanine aminotransferase levels remained elevated. Therefore, CPS1 becomes readily detectable upon hepatocyte apoptotic and necrotic death in culture or in vivo. Its abundance and short serum half-life, compared with alanine aminotransferase, suggest that it may be a useful prognostic biomarker in human and mouse liver injury.