Low penetrance of frequent ATP7B mutations explains the low prevalence of Wilson disease. Lessons from real-life registries.

BACKGROUND & AIMS: Wilson disease (WD) is a copper metabolism disorder caused by mutations in ATP7B gene, with significant clinical variability. Several studies have analyzed the prevalence and penetrance of mutations. We evaluated both characteristics for our more frequent mutations. METHODS: Evaluation of 260 patients from the National Registry: clinical, analytical and genetic data. Estimation of homozygotes and total cases according to Hardy-Weinberg equilibrium and comparison with Registry records. RESULTS: The estimated number of homozygotes were higher than registered: p.Met645Arg (1949/6), p.His1069Gln (20/8), p.Leu708Pro (63/24) and p.Gly869Arg (147/0). p.Met645Arg homozygotes presented less cirrhosis at diagnosis, extrahepatic disease and Kayser-Fleischer ring (KFR) and more presymptomatic cases and diagnosis after 40 years of age than p.Leu708Pro and p.His1069Gln homozygotes. p.Met645Arg homozygotes presented more late diagnosis than p.Met645Arg compound heterozygotes. Compound heterozygotes carrying p.Met645Arg or p.Gly869Arg showed less cirrhosis at diagnosis, KFR and neurological symptoms and more hepatic and presymptomatic cases, despite clearly low ceruloplasmin levels. The estimated prevalence was 1:3.785, predicting more than 10.500 patients. CONCLUSIONS: The widespread mutations p.Met645Arg and p.Gly869Arg show low penetrance. WD might be underdiagnosed in Spain due to less severe phenotype of the most frequent mutations, a crucial fact to avoid misdiagnosis and to offer early therapy.

Ammonia-induced stress response in liver disease progression and hepatic encephalopathy.

Ammonia levels are orchestrated by a series of complex interrelated pathways in which the urea cycle has a central role. Liver dysfunction leads to an accumulation of ammonia, which is toxic and is strongly associated with disruption of potassium homeostasis, mitochondrial dysfunction, oxidative stress, inflammation, hypoxaemia and dysregulation of neurotransmission. Hyperammonaemia is a hallmark of hepatic encephalopathy and has been strongly associated with liver-related outcomes in patients with cirrhosis and liver failure. In addition to the established role of ammonia as a neurotoxin in the pathogenesis of hepatic encephalopathy, an increasing number of studies suggest that it can lead to hepatic fibrosis progression, sarcopenia, immune dysfunction and cancer. However, elevated systemic ammonia levels are uncommon in patients with metabolic dysfunction-associated steatotic liver disease. A clear causal relationship between ammonia-induced immune dysfunction and risk of infection has not yet been definitively proven. In this Review, we discuss the mechanisms by which ammonia produces its diverse deleterious effects and their clinical relevance in liver diseases, the importance of measuring ammonia levels for the diagnosis of hepatic encephalopathy, the prognosis of patients with cirrhosis and liver failure, and how our knowledge of inter-organ ammonia metabolism is leading to the development of novel therapeutic approaches.

One-step non-invasive diagnosis of metabolic dysfunction-associated steatohepatitis and fibrosis in high-risk population.

BACKGROUND AND AIM: Type 2 Diabetes mellitus (T2DM), age, and obesity are risk factors for metabolic dysfunction-associated steatotic liver disease (MASLD). We aimed to assess the performance of non-invasive tests (NITs) for the diagnosis of metabolic dysfunction-associated steatohepatitis (MASH) and fibrosis in high-risk subjects. METHODS: Multicentre cross-sectional study that included 124 biopsy-proven MASLD in more than 50 years-old patients with overweight/obesity and T2DM. Vibration-controlled transient elastography, Fibrosis-4 index (FIB-4), Non-alcoholic fatty liver disease fibrosis score (NFS), OWLiver Panel (OWLiver DM2 + Metabolomics-Advanced Steatohepatitis Fibrosis Score -MASEF) and FibroScan-AST were performed. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and area under the receiver operating characteristic curve (AUC) were calculated. NITs were assessed individually and in sequential/parallel combinations. RESULTS: 35 (28.2%) patients had early MASH and 66 (53.2%) had MASH with significant fibrosis (at-risk MASH). The OWLiver Panel correctly classified 86.1% as MASH, showing an accuracy, sensitivity, specificity, PPV, and NPV of 0.77, 0.86, 0.35, 0.85, and 0.36, respectively. Class III obesity, diabetes control, or gender did not impact on the performance of the OWLiver Panel (p > 0.1). NITs for at-risk MASH showed an AUC > 0.70 except for NFS. MASEF showed the highest accuracy and NPV for at-risk MASH (AUC 0.77 [0.68-0.85], NPV 72%) and advanced fibrosis (AUC 0.80 [0.71-0.88], NPV 92%). Combinations of NITs for the identification of at-risk MASH did not provide any additional benefit over using MASEF alone. CONCLUSION: One-step screening strategy with the OWLiver Panel has high accuracy to detect MASH and at-risk MASH in high-risk subjects for MASLD.

Fibroblast growth factor 21 is a hepatokine involved in MASLD progression.

AIM: We aimed to assess the role of FGF21 in metabolic dysfunction-associated steatotic liver disease (MASLD) at a multi-scale level. METHODS: We used human MASLD pathology samples for FGF21 gene expression analyses (qPCR and RNAseq), serum to measure circulating FGF21 levels and DNA for genotyping the FGF21 rs838133 variant in both estimation and validation cohorts. A hepatocyte-derived cell line was exposed to free fatty acids at different timepoints. Finally, C57BL/6J mice were fed a high-fat and choline-deficient diet (CDA-HFD) for 16 weeks to assess hepatic FGF21 protein expression and FGF21 levels by ELISA. RESULTS: A significant upregulation in FGF21 mRNA expression was observed in the liver analysed by both qPCR (fold change 5.32 ± 5.25 vs. 0.59 ± 0.66; p = 0.017) and RNA-Seq (3.5 fold; FDR: 0.006; p < 0.0001) in MASLD patients vs. controls. Circulating levels of FGF21 were increased in patients with steatohepatitis vs. bland steatosis (386.6 ± 328.9 vs. 297.9 ± 231.5 pg/mL; p = 0.009). Besides, sex, age, A-allele from FGF21, GG genotype from PNPLA3, ALT, type 2 diabetes mellitus and BMI were independently associated with MASH and significant fibrosis in both estimation and validation cohorts. In vitro exposure of Huh7.5 cells to high concentrations of free fatty acids (FFAs) resulted in overexpression of FGF21 (p < 0.001). Finally, Circulating FGF21 levels and hepatic FGF21 expression were found to be significantly increased (p < 0.001) in animals under CDA-HFD. CONCLUSIONS: Hepatic and circulating FGF21 expression was increased in MASH patients, in Huh7.5 cells under FFAs and in CDA-HFD animals. The A-allele from the rs838133 variant was also associated with an increased risk of steatohepatitis and significant and advanced fibrosis in MASLD patients.

Rituximab is a safe and effective alternative treatment for patients with autoimmune hepatitis: Results from the ColHai registry.

BACKGROUND AND AIMS: Small series suggest that rituximab could be effective as treatment for autoimmune hepatitis (AIH), although data are scarce. We aimed to evaluate the efficacy and safety of rituximab in different cohorts of patients with AIH. METHODS: Multicentre retrospective analysis of the 35 patients with AIH and its variant forms treated with rituximab and included in the ColHai registry between 2015 and 2023. RESULTS: Most patients were female (83%), 10 (29%) had cirrhosis and four (11.4%) variant forms of AIH. Indication for rituximab were as follows: 14(40%) refractory AIH, 19(54%) concomitant autoimmune or haematological disorder, 2(6%) intolerance to prior treatments. In three (9%) subjects with a concomitant disorder, rituximab was the first therapy for AIH. Overall, 31 (89%) patients achieved or maintained complete biochemical response (CBR), including the three in first-line therapy. No difference in CBR was observed according to rituximab indication (refractory AIH 86% vs. concomitant disorders 90%, p = .824) or cirrhosis (80% vs. 92%, p = .319). Rituximab was associated with a significant reduction in corticosteroids (median dose: prior 20 vs. post 5 mg, p < .001) and the discontinuation of ≥1 immunosuppressant in 47% of patients. Flare-free rate at 1st, 2nd and 3rd year was 86%, 73% and 62% respectively. Flares were not associated with the development of liver failure and were successfully managed with repeated doses of rituximab and/or increased corticosteroids. Three (9%) patients experienced infusion-related adverse events (1 anaphylaxis and 2 flu-like symptoms) and five (14%) infections. CONCLUSION: Rituximab is safe and effective in patients with refractory AIH and those treated due to concomitant autoimmune or haematological disorders.

Development and Validation of a Scoring System to Predict Response to Obeticholic Acid in Primary Biliary Cholangitis.

BACKGROUND & AIMS: Obeticholic acid (OCA) is the only licensed second-line therapy for primary biliary cholangitis (PBC). With novel therapeutics in advanced development, clinical tools are needed to tailor the treatment algorithm. We aimed to derive and externally validate the OCA response score (ORS) for predicting the response probability of individuals with PBC to OCA. METHODS: We used data from the Italian RECAPITULATE (N = 441) and the IBER-PBC (N = 244) OCA real-world prospective cohorts to derive/validate a score including widely available variables obtained either pre-treatment (ORS) or also after 6 months of treatment (ORS+). Multivariable Cox regressions with backward selection were applied to obtain parsimonious predictive models. The predicted outcomes were biochemical response according to POISE (alkaline phosphatase [ALP]/upper limit of normal [ULN]<1.67 with a reduction of at least 15%, and normal bilirubin), or ALP/ULN<1.67, or normal range criteria (NR: normal ALP, alanine aminotransferase [ALT], and bilirubin) up to 24 months. RESULTS: Depending on the response criteria, ORS included age, pruritus, cirrhosis, ALP/ULN, ALT/ULN, GGT/ULN, and bilirubin. ORS+ also included ALP/ULN and bilirubin after 6 months of OCA therapy. Internally validated c-statistics for ORS were 0.75, 0.78, and 0.72 for POISE, ALP/ULN<1.67, and NR response, which raised to 0.83, 0.88, and 0.81 with ORS+, respectively. The respective performances in validation were 0.70, 0.72, and 0.71 for ORS and 0.80, 0.84, and 0.78 for ORS+. Results were consistent across groups with mild/severe disease. CONCLUSIONS: We developed and externally validated a scoring system capable to predict OCA response according to different criteria. This tool will enhance a stratified second-line therapy model to streamline standard care and trial delivery in PBC.

The biochemical pattern defines MASLD phenotypes linked to distinct histology and prognosis.

BACKGROUND: MASLD can manifest as hepatocellular damage, which can result in mild elevation of aminotransferases. However, in some patients, MASLD presents with cholestatic pattern. OBJECTIVE: To assess the impact of the biochemical pattern on the natural course of MASLD, including liver damage in histology, the accuracy of non-invasive tests(NITs), and prognosis. METHODS: Multicenter study enrolling 2156 patients with biopsy-proven MASLD, who were classified based on their[ALT/ULN)]/[(ALP/ULN)] levels at the time of biopsy: (a) hepatocellular pattern(H), > 5; (b) mixed pattern(M),2-5; (c) cholestatic pattern(C), < 2. OUTCOMES: (a) histological evaluation of the single components of NAS, MASH, and fibrosis; (b) NITs and transient elastography assessing advanced fibrosis; (c) prognosis determined by the appearance of decompensated cirrhosis and death. RESULTS: Out of the 2156 patients, 22.9% exhibited the H-pattern, whilst 31.7% exhibited the C-pattern. Severe steatosis, ballooning, lobular inflammation, and MASH (56.4% H vs. 41.9% M vs. 31.9% C) were more common in H-pattern (p = 0.0001),whilst C-pattern was linked to cirrhosis (5.8% H vs. 5.6% M vs. 10.9% C; p = 0.0001). FIB-4(0.74(95% CI 0.69-0.79) vs. 0.83 (95% CI 0.80-0.85); p = 0.005) and Hepamet Fibrosis Score(0.77 (95% CI 0.69-0.85) vs. 0.84 (95% CI 0.80-0.87); p = 0.044)exhibited lower AUROCs in the H-pattern. The C-pattern[HR 2.37 (95% CI 1.12-5.02); p = 0.024], along with age, diabetes, and cirrhosis were independently associated with mortality. Most patients maintained their initial biochemical pattern during the second evaluation. CONCLUSIONS: The H-pattern exhibited greater necro-inflammation in the histology than the C-pattern, whereas the latter showed more cirrhosis. The accuracy of NITs in detecting fibrosis was decreased in H-pattern. The occurrence of decompensated events and mortality was predominant in C-pattern. Therefore, identifying MASLD phenotypes based on the biochemical presentation could be relevant for clinical practice.

Predictive factors for decompensating events in patients with cirrhosis with primary biliary cholangitis under different lines of therapy.

BACKGROUND AND AIMS: The landscape in primary biliary cholangitis (PBC) has changed with the advent of second-line treatments. However, the use of obeticholic acid (OCA) and fibrates in PBC-related cirrhosis is challenging. We assessed the impact of receiving a second-line therapy as a risk factor for decompensated cirrhosis in a real-world population with cirrhosis and PBC, and identify the predictive factors for decompensated cirrhosis in these patients. APPROACH AND RESULTS: Multicenter study enrolling 388 patients with PBC-cirrhosis from the Spanish ColHai registry. Biopsy (20%), ultrasound (59%), or transient elastography (21%) defined cirrhosis, and the presence of varices and splenomegaly defined clinically significant portal hypertension (CSPH). Paris-II and PBC OCA international study of efficacy criteria determined the response to ursodeoxycholic acid (UDCA), fibrates (n=93), and OCA (n=104). The incidence of decompensated cirrhosis decreased for UDCA versus OCA or fibrates in the real-world population, but they were similar considering the propensity score-matched cohort (UDCA 3.77 vs. second-line therapy 4.5 100 persons-year, respectively), as patients on second-line therapy exhibited advanced liver disease. Consequently, GGT, albumin, platelets, clinically significant portal hypertension, and UDCA response were associated with a decompensating event. OCA response (achieved in 52% of patients) was associated with bilirubin (OR 0.21 [95% CI: 0.06-0.73]) and AST (OR 0.97 [95% CI: 0.95-0.99]), while fibrate response (achieved in 55% of patients) with AST [OR 0.96 (95% CI: 0.95-0.98]). In patients treated with OCA, drug response (sHR 0.23 [95% CI: 0.08-0.64]), diabetes (sHR 5.62 [95% CI: 2.02-15.68]), albumin (sHR 0.34 [95% CI: 0.13-0.89]), and platelets (sHR 0.99 [95% CI: 0.98-1.00]) were related to decompensation. In patients treated with fibrate, drug response (sHR 0.36 (95% CI: 0.14-0.95]), albumin (sHR 0.36 (95% CI: 0.16-0.81]), and clinically significant portal hypertension (sHR 3.70 (95% CI: 1.17-11.70]) were associated with decompensated cirrhosis. CONCLUSIONS: Advanced PBC, rather than OCA and fibrates, was found to be associated with decompensating events. Therefore, biochemical and clinical variables should be considered when making decisions about the management of these drugs. Moreover, a positive response to OCA and fibrates reduced the risk of decompensation.

Serum ferritin levels can predict long-term outcomes in patients with metabolic dysfunction-associated steatotic liver disease.

OBJECTIVE: Hyperferritinaemia is associated with liver fibrosis severity in patients with metabolic dysfunction-associated steatotic liver disease (MASLD), but the longitudinal implications have not been thoroughly investigated. We assessed the role of serum ferritin in predicting long-term outcomes or death. DESIGN: We evaluated the relationship between baseline serum ferritin and longitudinal events in a multicentre cohort of 1342 patients. Four survival models considering ferritin with confounders or non-invasive scoring systems were applied with repeated five-fold cross-validation schema. Prediction performance was evaluated in terms of Harrell's C-index and its improvement by including ferritin as a covariate. RESULTS: Median follow-up time was 96 months. Liver-related events occurred in 7.7%, hepatocellular carcinoma in 1.9%, cardiovascular events in 10.9%, extrahepatic cancers in 8.3% and all-cause mortality in 5.8%. Hyperferritinaemia was associated with a 50% increased risk of liver-related events and 27% of all-cause mortality. A stepwise increase in baseline ferritin thresholds was associated with a statistical increase in C-index, ranging between 0.02 (lasso-penalised Cox regression) and 0.03 (ridge-penalised Cox regression); the risk of developing liver-related events mainly increased from threshold 215.5 µg/L (median HR=1.71 and C-index=0.71) and the risk of overall mortality from threshold 272 µg/L (median HR=1.49 and C-index=0.70). The inclusion of serum ferritin thresholds (215.5 µg/L and 272 µg/L) in predictive models increased the performance of Fibrosis-4 and Non-Alcoholic Fatty Liver Disease Fibrosis Score in the longitudinal risk assessment of liver-related events (C-indices>0.71) and overall mortality (C-indices>0.65). CONCLUSIONS: This study supports the potential use of serum ferritin values for predicting the long-term prognosis of patients with MASLD.

Novel insights into metabolic-associated steatotic liver disease preclinical models.

Metabolic-associated steatotic liver disease (MASLD) encompasses a wide spectrum of metabolic conditions associated with an excess of fat accumulation in the liver, ranging from simple hepatic steatosis to cirrhosis and hepatocellular carcinoma. Finding appropriate tools to study its development and progression is essential to address essential unmet therapeutic and staging needs. This review discusses advantages and shortcomings of different dietary, chemical and genetic factors that can be used to mimic this disease and its progression in mice from a hepatic and metabolic point of view. Also, this review will highlight some additional factors and considerations that could have a strong impact on the outcomes of our model to end up providing recommendations and a checklist to facilitate the selection of the appropriate MASLD preclinical model based on clinical aims.

Crohn´s disease is an independent risk factor for liver fibrosis in patients with inflammatory bowel disease and non-alcoholic fatty liver disease.

BACKGROUND AND AIMS: Controversial data have been reported regarding the prevalence of Non-Alcoholic Fatty Liver Disease (NAFLD) in Inflammatory Bowel Disease (IBD) population and IBD-related risk factors. The aim of the study was to assess the prevalence and risk factors associated with NAFLD and liver fibrosis in IBD participants compared with non-IBD controls. METHODS: Cross-sectional, case-control study including 741 IBD cases and 170 non-IBD controls, matched by sex and age. All participants underwent liver ultrasound, transient elastography and laboratory tests. A logistic regression multivariable analysis was performed adjusting for classic metabolic risk factors and history of systemic steroid use. RESULTS: The prevalence of NAFLD and significant liver fibrosis was 45 % and 10 % in IBD group, and 40 % and 2.9 % in non-IBD group (p = 0.255 and 0.062, respectively). Longer IBD duration (aOR 1.02 95% CI (1.001-1.04)) and older age at IBD diagnosis (aOR 1.02 95 % CI (1.001-1.04)) were independent risk factors for NAFLD in IBD group. Crohn´s Disease was an independent risk factor for significant liver fibrosis in participants with IBD and NAFLD (aOR 3.97 95 % CI (1.78-8.96)). NAFLD occurred at lower BMI levels in IBD group with NAFLD compared to non-IBD group with NAFLD (aOR 0.92 95 % CI (0.87-0.98)). CONCLUSIONS: Although we found no differences in the prevalence of NAFLD and liver fibrosis between IBD group and non-IBD group, our findings suggest that liver fibrosis progression should be closely monitored in patients with concomitant CD and NAFLD, more in particular in those with long standing active disease.

Serum identification of at-risk MASH: The metabolomics-advanced steatohepatitis fibrosis score (MASEF).

BACKGROUND: Early identification of those with NAFLD activity score ≥ 4 and significant fibrosis (≥F2) or at-risk metabolic dysfunction-associated steatohepatitis (MASH) is a priority as these patients are at increased risk for disease progression and may benefit from therapies. We developed and validated a highly specific metabolomics-driven score to identify at-risk MASH. METHODS: We included derivation (n = 790) and validation (n = 565) cohorts from international tertiary centers. Patients underwent laboratory assessment and liver biopsy for metabolic dysfunction-associated steatotic liver disease. Based on 12 lipids, body mass index, aspartate aminotransferase, and alanine aminotransferase, the MASEF score was developed to identify at-risk MASH and compared to the FibroScan-AST (FAST) score. We further compared the performance of a FIB-4 + MASEF algorithm to that of FIB-4 + liver stiffness measurements (LSM) by vibration-controlled transient elastography (VCTE). RESULTS: The diagnostic performance of the MASEF score showed an area under the receiver-operating characteristic curve, sensitivity, specificity, and positive and negative predictive values of 0.76 (95% CI 0.72-0.79), 0.69, 0.74, 0.53, and 0.85 in the derivation cohort, and 0.79 (95% CI 0.75-0.83), 0.78, 0.65, 0.48, and 0.88 in the validation cohort, while FibroScan-AST performance in the validation cohort was 0.74 (95% CI 0.68-0.79; p = 0.064), 0.58, 0.79, 0.67, and 0.73, respectively. FIB-4+MASEF showed similar overall performance compared with FIB-4 + LSM by VCTE ( p = 0.69) to identify at-risk MASH. CONCLUSION: MASEF is a promising diagnostic tool for the assessment of at-risk MASH. It could be used alternatively to LSM by VCTE in the algorithm that is currently recommended by several guidance publications.

Circular RNAs in non-alcoholic fatty liver disease: Functions and clinical significance.

Nonalcoholic fatty liver disease (NAFLD), which affects approximately 25% of the global population, is an urgent health issue leading to various metabolic comorbidities. Circular RNAs (circRNAs), covalently closed RNA molecules, are characterized by ubiquity, diversity, stability, and conservatism. Indeed, they participate in various biological processes via distinct mechanisms that could modify the natural history of NAFLD. In this review, we briefly introduce the biogenesis, characteristics, and biological functions of circRNAs. Furthermore, we summarize circRNAs expression profiles in NAFLD by intersecting seven sequencing data sets and describe the cellular roles of circRNAs and their potential advantages as biomarkers of NAFLD. In addition, we emphatically discuss the exosomal non-coding RNA sorting mechanisms and possible functions in recipient cells. Finally, we extensively discuss the potential application of targeting disease-related circRNAs and competing endogenous RNA networks through gain-of-function and loss-of-function approaches in targeted therapy of NAFLD.

Liver cancer stem cell dissemination and metastasis: uncovering the role of NRCAM in hepatocellular carcinoma.

BACKGROUND: Liver cancer stem cells (LCSCs) play an important role in hepatocellular carcinoma (HCC), but the mechanisms that link LCSCs to HCC metastasis remain largely unknown. This study aims to reveal the contributions of NRCAM to LCSC function and HCC metastasis, and further explore its mechanism in detail. METHODS: 117 HCC and 29 non-HCC patients with focal liver lesions were collected and analyzed to assess the association between NRCAM and HCC metastasis. Single-cell RNA sequencing (scRNA-seq) was used to explore the biological characteristics of cells with high NRCAM expression in metastatic HCC. The role and mechanism of NRCAM in LCSC dissemination and metastasis was explored in vitro and in vivo using MYC-driven LCSC organoids from murine liver cells. RESULTS: Serum NRCAM is associated with HCC metastasis and poor prognosis. A scRNA-seq analysis identified that NRCAM was highly expressed in LCSCs with MYC activation in metastatic HCC. Moreover, NRCAM facilitated LCSC migration and invasion, which was confirmed in MYC-driven LCSC organoids. The in vivo tumor allografts demonstrated that NRCAM mediated intra-hepatic/lung HCC metastasis by enhancing the ability of LCSCs to escape from tumors into the bloodstream. Nrcam expression inhibition in LCSCs blocked HCC metastasis. Mechanistically, NRCAM activated epithelial-mesenchymal transition (EMT) and metastasis-related matrix metalloproteinases (MMPs) through the MACF1 mediated ß-catenin signaling pathway in LCSCs. CONCLUSIONS: LCSCs typified by high NRCAM expression have a strong ability to invade and migrate, which is an important factor leading to HCC metastasis.

Neuroblastoma RAS viral oncogene homolog (N-RAS) deficiency aggravates liver injury and fibrosis.

Progressive hepatic damage and fibrosis are major features of chronic liver diseases of different etiology, yet the underlying molecular mechanisms remain to be fully defined. N-RAS, a member of the RAS family of small guanine nucleotide-binding proteins also encompassing the highly homologous H-RAS and K-RAS isoforms, was previously reported to modulate cell death and renal fibrosis; however, its role in liver damage and fibrogenesis remains unknown. Here, we approached this question by using N-RAS deficient (N-RAS-/-) mice and two experimental models of liver injury and fibrosis, namely carbon tetrachloride (CCl4) intoxication and bile duct ligation (BDL). In wild-type (N-RAS+/+) mice both hepatotoxic procedures augmented N-RAS expression in the liver. Compared to N-RAS+/+ counterparts, N-RAS-/- mice subjected to either CCl4 or BDL showed exacerbated liver injury and fibrosis, which was associated with enhanced hepatic stellate cell (HSC) activation and leukocyte infiltration in the damaged liver. At the molecular level, after CCl4 or BDL, N-RAS-/- livers exhibited augmented expression of necroptotic death markers along with JNK1/2 hyperactivation. In line with this, N-RAS ablation in a human hepatocytic cell line resulted in enhanced activation of JNK and necroptosis mediators in response to cell death stimuli. Of note, loss of hepatic N-RAS expression was characteristic of chronic liver disease patients with fibrosis. Collectively, our study unveils a novel role for N-RAS as a negative controller of the progression of liver injury and fibrogenesis, by critically downregulating signaling pathways leading to hepatocyte necroptosis. Furthermore, it suggests that N-RAS may be of potential clinical value as prognostic biomarker of progressive fibrotic liver damage, or as a novel therapeutic target for the treatment of chronic liver disease.