Recurrent alcohol-associated hepatitis is common and is associated with increased mortality.

BACKGROUND AND AIMS: Alcohol relapse after surviving an episode of alcohol-associated hepatitis (AH) is common. However, the clinical features, risk factors, and prognostic implications of recurrent alcohol-associated hepatitis (RAH) are not well described. APPROACH AND RESULTS: A registry-based study was done of patients admitted to 28 Spanish hospitals for an episode of AH between 2014 and 2021. Baseline demographics and laboratory variables were collected. Risk factors for RAH were investigated using Cox regression analysis. We analyzed the severity of the index episodes of AH and compared it to that of RAH. Long-term survival was assessed by Kaplan-Meier curves and log-rank tests. A total of 1118 patients were included in the analysis, 125 (11%) of whom developed RAH during follow-up (median: 17 [7-36] months). The incidence of RAH in patients resuming alcohol use was 22%. The median time to recurrence was 14 (8-29) months. Patients with RAH had more psychiatric comorbidities. Risk factors for developing RAH included age <50 years, alcohol use >10 U/d, and history of liver decompensation. RAH was clinically more severe compared to the first AH (higher MELD, more frequent ACLF, and HE). Moreover, alcohol abstinence during follow-up was less common after RAH (18% vs. 45%, p <0.001). Most importantly, long-term mortality was higher in patients who developed RAH (39% vs. 21%, p = 0.026), and presenting with RAH independently predicted high mortality (HR: 1.55 [1.11-2.18]). CONCLUSIONS: RAH is common and has a more aggressive clinical course, including increased mortality. Patients surviving an episode of AH should undergo intense alcohol use disorder therapy to prevent RAH.

Anti-miR-873-5p improves alcohol-related liver disease by enhancing hepatic deacetylation via SIRT1.

Background & Aims: Current therapies for the treatment of alcohol-related liver disease (ALD) have proven largely ineffective. Patients relapse and the disease progresses even after liver transplantation. Altered epigenetic mechanisms are characteristic of alcohol metabolism given excessive acetate and NAD depletion and play an important role in liver injury. In this regard, novel therapeutic approaches based on epigenetic modulators are increasingly proposed. MicroRNAs, epigenetic modulators acting at the post-transcriptional level, appear to be promising new targets for the treatment of ALD. Methods: MiR-873-5p levels were measured in 23 liver tissue from Patients with ALD, and GNMT levels during ALD were confirmed using expression databases (transcriptome n = 62, proteome n = 68). High-resolution proteomics and metabolomics in mice following the Gao-binge model were used to investigate miR-873-5p expression in ALD. Hepatocytes exposed to 50 mM alcohol for 12 h were used to study toxicity. The effect of anti-miR-873-5p in the treatment outcomes of ALD was investigated. Results: The analysis of human and preclinical ALD samples revealed increased expression of miR-873-5p in the liver. Interestingly, there was an inverse correlation with NNMT, suggesting a novel mechanism for NAD depletion and aberrant acetylation during ALD progression. High-resolution proteomics and metabolomics identified miR-873-5p as a key regulator of NAD metabolism and SIRT1 deacetylase activity. Anti-miR-873-5p reduced NNMT activity, fuelled the NAD salvage pathway, restored the acetylome, and modulated the levels of NF-κB and FXR, two known SIRT1 substrates, thereby protecting the liver from apoptotic and inflammatory processes, and improving bile acid homeostasis. Conclusions: These data indicate that targeting miR-873-5p, a repressor of GNMT previously associated with NAFLD and acetaminophen-induced liver failure. is a novel and attractive approach to treating alcohol-induced hepatoxicity. Impact and implications: The role of miR-873-5p has not been explicitly examined in the progression of ALD, a pathology with no therapeutic options. In this study, inhibiting miR-873-5p exerted hepatoprotective effects against ALD through rescued SIRT1 activity and consequently restored bile acid homeostasis and attenuated the inflammatory response. Targeting hepatic miR-873-5p may represent a novel therapeutic approach for the treatment of ALD.

Alcoholic Foamy Degeneration, an Entity Resembling Alcohol-Associated Hepatitis: Diagnosis, Prognosis, and Molecular Profiling.

BACKGROUND & AIMS: Alcoholic foamy degeneration (AFD) is a condition with similar clinical presentation to alcohol-associated hepatitis (AH), but with a specific histologic pattern. Information regarding the prevalence and prognosis of AFD is scarce and there are no tools for a noninvasive diagnosis. METHODS: A cohort of patients admitted to the Hospital Clinic of Barcelona for clinical suspicion of AH who underwent liver biopsy was included. Patients were classified as AFD, AH, or other findings, according to histology. Clinical features, histology, and genetic expression of liver biopsy specimens were analyzed. The accuracy of National Institute on Alcohol Abuse and Alcoholism criteria and laboratory parameters for differential diagnosis were investigated. RESULTS: Of 230 patients with a suspicion of AH, 18 (8%) met histologic criteria for AFD, 184 (80%) had definite AH, and 28 (12%) had other findings. In patients with AFD, massive steatosis was more frequent and the fibrosis stage was lower. AFD was characterized by down-regulation of liver fibrosis and inflammation genes and up-regulation of lipid metabolism and mitochondrial function genes. Patients with AFD had markedly better long-term survival (100% vs 57% in AFD vs AH; P = .002) despite not receiving corticosteroid treatment, even in a model for end-stage liver disease-matched sensitivity analysis. Serum triglyceride levels had an area under the receiver operating characteristic of 0.886 (95% CI, 0.807-0.964) for the diagnosis of AFD, whereas the National Institute on Alcohol Abuse and Alcoholism criteria performed poorly. A 1-step algorithm using triglyceride levels of 225 mg/dL (sensitivity, 0.77; specificity, 0.90; and Youden index, 0.67) is proposed for differential diagnosis. CONCLUSIONS: AFD in the setting of suspicion of AH is not uncommon. A differential diagnosis is important because prognosis and treatment differ largely. Triglyceride levels successfully identify most patients with AFD and may be helpful in decision making.

Therapeutic targeting of adipose tissue macrophages ameliorates liver fibrosis in non-alcoholic fatty liver disease.

Background & Aims: : The accumulation of adipose tissue macrophages (ATMs) in obesity has been associated with hepatic injury. However, the contribution of ATMs to hepatic fibrosis in non-alcoholic fatty liver disease (NAFLD) remains to be elucidated. Herein, we investigate the relationship between ATMs and liver fibrosis in patients with patients with NAFLD and evaluate the impact of modulation of ATMs over hepatic fibrosis in an experimental non-alcoholic steatohepatitis (NASH) model. Methods: Adipose tissue and liver biopsies from 42 patients with NAFLD with different fibrosis stages were collected. ATMs were characterised by immunohistochemistry and flow cytometry and the correlation between ATMs and liver fibrosis stages was assessed. Selective modulation of the ATM phenotype was achieved by i.p. administration of dextran coupled with dexamethasone in diet-induced obesity and NASH murine models. Chronic administration effects were evaluated by histology and gene expression analysis in adipose tissue and liver samples. In vitro crosstalk between human ATMs and hepatic stellate cells (HSCs) and liver spheroids was performed. Results: Patients with NAFLD presented an increased accumulation of pro-inflammatory ATMs that correlated with hepatic fibrosis. Long-term modulation of ATMs significantly reduced pro-inflammatory phenotype and ameliorated adipose tissue inflammation. Moreover, ATMs modulation was associated with an improvement in steatosis and hepatic inflammation and significantly reduced fibrosis progression in an experimental NASH model. In vitro, the reduction of the pro-inflammatory phenotype of human ATMs with dextran-dexamethasone treatment reduced the secretion of inflammatory chemokines and directly attenuated the pro-fibrogenic response in HSCs and liver spheroids. Conclusions: Pro-inflammatory ATMs increase in parallel with fibrosis degree in patients with NAFLD and their modulation in an experimental NASH model improves liver fibrosis, uncovering the potential of ATMs as a therapeutic target to mitigate liver fibrosis in NAFLD. Impact and implications: We report that human adipose tissue pro-inflammatory macrophages correlate with hepatic fibrosis in non-alcoholic fatty liver disease (NAFLD). Furthermore, the modulation of adipose tissue macrophages (ATMs) by dextran-nanocarrier conjugated with dexamethasone shifts the pro-inflammatory phenotype of ATMs to an anti-inflammatory phenotype in an experimental murine model of non-alcoholic steatohepatitis. This shift ameliorates adipose tissue inflammation, hepatic inflammation, and fibrosis. Our results highlight the relevance of adipose tissue in NAFLD pathophysiology and unveil ATMs as a potential target for NAFLD.

Identification and experimental validation of druggable epigenetic targets in hepatoblastoma.

BACKGROUND & AIMS: Hepatoblastoma (HB) is the most frequent childhood liver cancer. Patients with aggressive tumors have limited therapeutic options; therefore, a better understanding of HB pathogenesis is needed to improve treatment. HBs have a very low mutational burden; however, epigenetic alterations are increasingly recognized. We aimed to identify epigenetic regulators consistently dysregulated in HB and to evaluate the therapeutic efficacy of their targeting in clinically relevant models. METHODS: We performed a comprehensive transcriptomic analysis of 180 epigenetic genes. Data from fetal, pediatric, adult, peritumoral (n = 72) and tumoral (n = 91) tissues were integrated. Selected epigenetic drugs were tested in HB cells. The most relevant epigenetic target identified was validated in primary HB cells, HB organoids, a patient-derived xenograft model, and a genetic mouse model. Transcriptomic, proteomic and metabolomic mechanistic analyses were performed. RESULTS: Altered expression of genes regulating DNA methylation and histone modifications was consistently observed in association with molecular and clinical features of poor prognosis. The histone methyltransferase G9a was markedly upregulated in tumors with epigenetic and transcriptomic traits of increased malignancy. Pharmacological targeting of G9a significantly inhibited growth of HB cells, organoids and patient-derived xenografts. Development of HB induced by oncogenic forms of ß-catenin and YAP1 was ablated in mice with hepatocyte-specific deletion of G9a. We observed that HBs undergo significant transcriptional rewiring in genes involved in amino acid metabolism and ribosomal biogenesis. G9a inhibition counteracted these pro-tumorigenic adaptations. Mechanistically, G9a targeting potently repressed the expression of c-MYC and ATF4, master regulators of HB metabolic reprogramming. CONCLUSIONS: HBs display a profound dysregulation of the epigenetic machinery. Pharmacological targeting of key epigenetic effectors exposes metabolic vulnerabilities that can be leveraged to improve the treatment of these patients. IMPACT AND IMPLICATIONS: In spite of recent advances in the management of hepatoblastoma (HB), treatment resistance and drug toxicity are still major concerns. This systematic study reveals the remarkable dysregulation in the expression of epigenetic genes in HB tissues. Through pharmacological and genetic experimental approaches, we demonstrate that the histone-lysine-methyltransferase G9a is an excellent drug target in HB, which can also be harnessed to enhance the efficacy of chemotherapy. Furthermore, our study highlights the profound pro-tumorigenic metabolic rewiring of HB cells orchestrated by G9a in coordination with the c-MYC oncogene. From a broader perspective, our findings suggest that anti-G9a therapies may also be effective in other c-MYC-dependent tumors.

Ductular reaction-associated neutrophils promote biliary epithelium proliferation in chronic liver disease.

BACKGROUND & AIMS: Ductular reaction expansion is associated with poor prognosis in patients with advanced liver disease. However, the mechanisms promoting biliary cell proliferation are largely unknown. Here, we identify neutrophils as drivers of biliary cell proliferation and the defective wound-healing response. METHODS: The intrahepatic localization of neutrophils was evaluated in patients with chronic liver disease. Neutrophil dynamics were analyzed by intravital microscopy and neutrophil-labeling assays in DDC-treated mice. Neutrophil depletion or inhibition of recruitment was achieved using a Ly6g antibody or a CXCR1/2 inhibitor, respectively. Mice deficient in PAD4 (peptidyl arginine deiminase 4) and ELANE/NE (neutrophil elastase) were used to investigate the mechanisms underlying ductular reaction expansion. RESULTS: In this study we describe a population of ductular reaction-associated neutrophils (DRANs), which are in direct contact with biliary epithelial cells in chronic liver diseases and whose numbers increased in parallel with disease progression. We show that DRANs are immobilized at the site of ductular reaction for a prolonged period of time. In addition, liver neutrophils display a unique phenotypic and transcriptomic profile, showing a decreased phagocytic capacity and increased oxidative burst. Depletion of neutrophils or inhibition of their recruitment reduces DRANs and the expansion of ductular reaction, while mitigating liver fibrosis and angiogenesis. Mechanistically, neutrophils deficient in PAD4 and ELANE abrogate neutrophil-induced biliary cell proliferation, thus indicating the role of neutrophil extracellular traps and elastase release in ductular reaction expansion. CONCLUSIONS: Overall, our study reveals the accumulation of DRANs as a hallmark of advanced liver disease and a potential therapeutic target to mitigate ductular reaction and the maladaptive wound-healing response. IMPACT AND IMPLICATIONS: Our results indicate that neutrophils are highly plastic and can have an extended lifespan. Moreover, we identify a new role of neutrophils as triggers of expansion of the biliary epithelium. Overall, the results of this study indicate that ductular reaction-associated neutrophils (or DRANs) are new players in the maladaptive tissue-healing response in chronic liver injury and may be a potential target for therapeutic interventions to reduce ductular reaction expansion and promote tissue repair in advanced liver disease.

Differentiation of Hepatic Stellate Cells from Pluripotent Stem Cells.

Hepatic stellate cells (HSCs) are non-parenchymal cells with a mesenchymal origin involved in vitamin A storage and extracellular matrix (ECM) homeostasis. In response to injury, HSCs activate and acquire myofibroblastic features, participating in the wound healing response. Upon chronic liver injury, HSCs become the main contributors to ECM deposition and to the progression of fibrosis. Due to their relevant roles in liver function and pathophysiology, it is of utmost importance to develop means to obtain HSCs for liver disease modeling and drug development. Here, we describe a directed differentiation protocol from human pluripotent stem cells (hPSCs) to obtain functional HSCs (PSC-HSCs). The procedure is based on the subsequent addition of growth factors during 12 days of differentiation. PSC-HSCs can be used for liver modeling and drug screening assays, hence emerging as a promising and reliable source of HSCs.

Hepatocyte Dedifferentiation Profiling In Alcohol-Related Liver Disease Identifies CXCR4 As A Driver Of Cell Reprogramming.

Background and Aims: Loss of hepatocyte identity is associated with impaired liver function in alcohol-related hepatitis (AH). In this context, hepatocyte dedifferentiation gives rise to cells with a hepatobiliary (HB) phenotype expressing biliary and hepatocytes markers and showing immature features. However, the mechanisms and the impact of hepatocyte dedifferentiation in liver disease are poorly understood. Methods: HB cells and ductular reaction (DR) cells were quantified and microdissected from liver biopsies from patients with alcohol-related liver disease (ALD). Hepatocyte- specific overexpression or deletion of CXCR4, and CXCR4 pharmacological inhibition were assessed in mouse liver injury. Patient-derived and mouse organoids were generated to assess plasticity. Results: Here we show that HB and DR cells are increased in patients with decompensated cirrhosis and AH, but only HB cells correlate with poor liver function and patients' outcome. Transcriptomic profiling of HB cells revealed the expression of biliary-specific genes and a mild reduction of hepatocyte metabolism. Functional analysis identified pathways involved in hepatocyte reprogramming, inflammation, stemness and cancer gene programs. CXCR4 pathway was highly enriched in HB cells, and correlated with disease severity and hepatocyte dedifferentiation. In vitro , CXCR4 was associated with biliary phenotype and loss of hepatocyte features. Liver overexpression of CXCR4 in chronic liver injury decreased hepatocyte specific gene expression profile and promoted liver injury. CXCR4 deletion or its pharmacological inhibition ameliorated hepatocyte dedifferentiation and reduced DR and fibrosis progression. Conclusions: This study shows the association of hepatocyte dedifferentiation with disease progression and poor outcome in AH. Moreover, the transcriptomic profiling of HB cells revealed CXCR4 as a new driver of hepatocyte-to-biliary reprogramming and as a potential therapeutic target to halt hepatocyte dedifferentiation in AH. Lay summary: Here we describe that hepatocyte dedifferentiation is associated with disease severity and a reduced synthetic capacity of the liver. Moreover, we identify the CXCR4 pathway as a driver of hepatocyte dedifferentiation and as a therapeutic target in alcohol-related hepatitis.

Hepatocyte dedifferentiation profiling in alcohol-related liver disease identifies CXCR4 as a driver of cell reprogramming.

BACKGROUND & AIMS: Loss of hepatocyte identity is associated with impaired liver function in alcohol-related hepatitis (AH). In this context, hepatocyte dedifferentiation gives rise to cells with a hepatobiliary (HB) phenotype expressing biliary and hepatocyte markers and showing immature features. However, the mechanisms and impact of hepatocyte dedifferentiation in liver disease are poorly understood. METHODS: HB cells and ductular reaction (DR) cells were quantified and microdissected from liver biopsies from patients with alcohol-related liver disease (ArLD). Hepatocyte-specific overexpression or deletion of C-X-C motif chemokine receptor 4 (CXCR4), and CXCR4 pharmacological inhibition were assessed in mouse liver injury. Patient-derived and mouse organoids were generated to assess plasticity. RESULTS: Here, we show that HB and DR cells are increased in patients with decompensated cirrhosis and AH, but only HB cells correlate with poor liver function and patients' outcome. Transcriptomic profiling of HB cells revealed the expression of biliary-specific genes and a mild reduction of hepatocyte metabolism. Functional analysis identified pathways involved in hepatocyte reprogramming, inflammation, stemness, and cancer gene programs. The CXCR4 pathway was highly enriched in HB cells and correlated with disease severity and hepatocyte dedifferentiation. In vitro, CXCR4 was associated with a biliary phenotype and loss of hepatocyte features. Liver overexpression of CXCR4 in chronic liver injury decreased the hepatocyte-specific gene expression profile and promoted liver injury. CXCR4 deletion or its pharmacological inhibition ameliorated hepatocyte dedifferentiation and reduced DR and fibrosis progression. CONCLUSIONS: This study shows the association of hepatocyte dedifferentiation with disease progression and poor outcome in AH. Moreover, the transcriptomic profiling of HB cells revealed CXCR4 as a new driver of hepatocyte-to-biliary reprogramming and as a potential therapeutic target to halt hepatocyte dedifferentiation in AH. IMPACT AND IMPLICATIONS: Here, we show that hepatocyte dedifferentiation is associated with disease severity and a reduced synthetic capacity of the liver. Moreover, we identify the CXCR4 pathway as a driver of hepatocyte dedifferentiation and as a therapeutic target in alcohol-related hepatitis. Therefore, this study reveals the importance of preserving strict control over hepatocyte plasticity in order to preserve liver function and promote tissue repair.

The outcome of boosting mitochondrial activity in alcohol-associated liver disease is organ-dependent.

BACKGROUND AND AIMS: Alcohol-associated liver disease (ALD) accounts for 70% of liver-related deaths in Europe, with no effective approved therapies. Although mitochondrial dysfunction is one of the earliest manifestations of alcohol-induced injury, restoring mitochondrial activity remains a problematic strategy due to oxidative stress. Here, we identify methylation-controlled J protein (MCJ) as a mediator for ALD progression and hypothesize that targeting MCJ may help in recovering mitochondrial fitness without collateral oxidative damage. APPROACH AND RESULTS: C57BL/6 mice [wild-type (Wt)] Mcj knockout and Mcj liver-specific silencing (MCJ-LSS) underwent the NIAAA dietary protocol (Lieber-DeCarli diet containing 5% (vol/vol) ethanol for 10 days, plus a single binge ethanol feeding at day 11). To evaluate the impact of a restored mitochondrial activity in ALD, the liver, gut, and pancreas were characterized, focusing on lipid metabolism, glucose homeostasis, intestinal permeability, and microbiota composition. MCJ, a protein acting as an endogenous negative regulator of mitochondrial respiration, is downregulated in the early stages of ALD and increases with the severity of the disease. Whole-body deficiency of MCJ is detrimental during ALD because it exacerbates the systemic effects of alcohol abuse through altered intestinal permeability, increased endotoxemia, and dysregulation of pancreatic function, which overall worsens liver injury. On the other hand, liver-specific Mcj silencing prevents main ALD hallmarks, that is, mitochondrial dysfunction, steatosis, inflammation, and oxidative stress, as it restores the NAD + /NADH ratio and SIRT1 function, hence preventing de novo lipogenesis and improving lipid oxidation. CONCLUSIONS: Improving mitochondrial respiration by liver-specific Mcj silencing might become a novel therapeutic approach for treating ALD.

Novel therapeutic avenues for the study of chronic liver disease and regeneration: The foundation of the Iberoamerican Consortium for the study of liver Cirrhosis.

Unfortunately, there is a gap of understanding in the pathophysiology of chronic liver disease due to the lack of experimental models that exactly mimic the human disease. Additionally, the diagnosis of patients is very poor due to the lack of biomarkers than can detect the disease in early stages. Thus, it is of utmost interest the generation of a multidisciplinary consortium from different countries with a direct translation. The present reports the meeting of the 2021 Iberoamerican Consortium for the study of liver Cirrhosis, held online, in October 2021. The meeting, was focused on the recent advancements in the field of chronic liver disease and cirrhosis with a specific focus on cell pathobiology and liver regeneration, molecular and cellular targets involved in non-alcoholic hepatic steatohepatitis, alcoholic liver disease (ALD), both ALD and western diet, and end-stage liver cirrhosis and hepatocellular carcinoma. In addition, the meeting highlighted recent advances in targeted novel technology (-omics) and opening therapeutic avenues in this field of research.

Distinct histopathological phenotypes of severe alcoholic hepatitis suggest different mechanisms driving liver injury and failure.

Intrahepatic neutrophil infiltration has been implicated in severe alcoholic hepatitis (SAH) pathogenesis; however, the mechanism underlying neutrophil-induced injury in SAH remains obscure. This translational study aims to describe the patterns of intrahepatic neutrophil infiltration and its involvement in SAH pathogenesis. Immunohistochemistry analyses of explanted livers identified two SAH phenotypes despite a similar clinical presentation, one with high intrahepatic neutrophils (Neuhi), but low levels of CD8+ T cells, and vice versa. RNA-Seq analyses demonstrated that neutrophil cytosolic factor 1 (NCF1), a key factor in controlling neutrophilic ROS production, was upregulated and correlated with hepatic inflammation and disease progression. To study specifically the mechanisms related to Neuhi in AH patients and liver injury, we used the mouse model of chronic-plus-binge ethanol feeding and found that myeloid-specific deletion of the Ncf1 gene abolished ethanol-induced hepatic inflammation and steatosis. RNA-Seq analysis and the data from experimental models revealed that neutrophilic NCF1-dependent ROS promoted alcoholic hepatitis (AH) by inhibiting AMP-activated protein kinase (a key regulator of lipid metabolism) and microRNA-223 (a key antiinflammatory and antifibrotic microRNA). In conclusion, two distinct histopathological phenotypes based on liver immune phenotyping are observed in SAH patients, suggesting a separate mechanism driving liver injury and/or failure in these patients.

Molecular characterization of chronic liver disease dynamics: From liver fibrosis to acute-on-chronic liver failure.

Background & Aims: The molecular mechanisms driving the progression from early-chronic liver disease (CLD) to cirrhosis and, finally, acute-on-chronic liver failure (ACLF) are largely unknown. Our aim was to develop a protein network-based approach to investigate molecular pathways driving progression from early-CLD to ACLF. Methods: Transcriptome analysis was performed on liver biopsies from patients at different liver disease stages, including fibrosis, compensated cirrhosis, decompensated cirrhosis and ACLF, and control healthy livers. We created 9 liver-specific disease-related protein-protein interaction networks capturing key pathophysiological processes potentially related to CLD. We used these networks as a framework and performed gene set-enrichment analysis (GSEA) to identify dynamic gene profiles of disease progression. Results: Principal component analyses revealed that samples clustered according to the disease stage. GSEA of the defined processes showed an upregulation of inflammation, fibrosis and apoptosis networks throughout disease progression. Interestingly, we did not find significant gene expression differences between compensated and decompensated cirrhosis, while ACLF showed acute expression changes in all the defined liver disease-related networks. The analyses of disease progression patterns identified ascending and descending expression profiles associated with ACLF onset. Functional analyses showed that ascending profiles were associated with inflammation, fibrosis, apoptosis, senescence and carcinogenesis networks, while descending profiles were mainly related to oxidative stress and genetic factors. We confirmed by qPCR the upregulation of genes of the ascending profile and validated our findings in an independent patient cohort. Conclusion: ACLF is characterized by a specific hepatic gene expression pattern related to inflammation, fibrosis, apoptosis, senescence and carcinogenesis. Moreover, the observed profile is significantly different from that of compensated and decompensated cirrhosis, supporting the hypothesis that ACLF should be considered a distinct entity. Lay summary: By using transjugular biopsies obtained from patients at different stages of chronic liver disease, we unveil the molecular pathogenic mechanisms implicated in the progression of chronic liver disease to cirrhosis and acute-on-chronic liver failure. The most relevant finding in this study is that patients with acute-on-chronic liver failure present a specific hepatic gene expression pattern distinct from that of patients at earlier disease stages. This gene expression pattern is mostly related to inflammation, fibrosis, angiogenesis, and senescence and apoptosis pathways in the liver.

The purinergic P2Y14 receptor links hepatocyte death to hepatic stellate cell activation and fibrogenesis in the liver.

Fibrosis contributes to ~45% of deaths in western countries. In chronic liver disease, fibrosis is a major factor determining outcomes, but efficient antifibrotic therapies are lacking. Although platelet-derived growth factor and transforming growth factor-ß constitute key fibrogenic mediators, they do not account for the well-established link between cell death and fibrosis in the liver. Here, we hypothesized that damage-associated molecular patterns (DAMPs) may link epithelial cell death to fibrogenesis in the injured liver. DAMP receptor screening identified purinergic receptor P2Y14 among several candidates as highly enriched in hepatic stellate cells (HSCs), the main fibrogenic cell type of the liver. Conversely, P2Y14 ligands uridine 5'-diphosphate (UDP)-glucose and UDP-galactose were enriched in hepatocytes and were released upon different modes of cell death. Accordingly, ligand-receptor interaction analysis that combined proteomic and single-cell RNA sequencing data revealed P2Y14 ligands and P2Y14 receptor as a link between dying cells and HSCs, respectively. Treatment with P2Y14 ligands or coculture with dying hepatocytes promoted HSC activation in a P2Y14-dependent manner. P2Y14 ligands activated extracellular signal-regulated kinase (ERK) and Yes-associated protein (YAP) signaling in HSCs, resulting in ERK-dependent HSC activation. Global and HSC-selective P2Y14 deficiency attenuated liver fibrosis in multiple mouse models of liver injury. Functional expression of P2Y14 was confirmed in healthy and diseased human liver and human HSCs. In conclusion, P2Y14 ligands and their receptor constitute a profibrogenic DAMP pathway that directly links cell death to fibrogenesis.

Clinical, histological and molecular profiling of different stages of alcohol-related liver disease.

OBJECTIVE: Alcohol-related liver disease (ALD) ranges from never-decompensated ALD (ndALD) to the life-threatening decompensated phenotype, known as alcohol-related hepatitis (AH). A multidimensional study of the clinical, histological and molecular features of these subtypes is lacking. DESIGN: Two large cohorts of patients were recruited in an international, observational multicentre study: a retrospective cohort of patients with ndALD (n=110) and a prospective cohort of patients with AH (n=225). Clinical, analytical, immunohistochemistry and hepatic RNA microarray analysis of both disease phenotypes were performed. RESULTS: Age and mean alcohol intake were similar in both groups. AH patients had greater aspartate amino transferase/alanine amino transferase ratio and lower gamma-glutamyl transferase levels than in ndALD patients. Patients with AH demonstrated profound liver failure and increased mortality. One-year mortality was 10% in ndALD and 50% in AH. Histologically, steatosis grade, ballooning and pericellular fibrosis were similar in both groups, while advanced fibrosis, Mallory-Denk bodies, bilirubinostasis, severe neutrophil infiltration and ductular reaction were more frequent among AH patients. Transcriptome analysis revealed a profound gene dysregulation within both phenotypes when compare to controls. While ndALD was characterised by deregulated expression of genes involved in matrisome and immune response, the development of AH resulted in a marked deregulation of genes involved in hepatocyte reprogramming and bile acid metabolism. CONCLUSIONS: Despite comparable alcohol intake, AH patients presented with worse liver function compared with ndALD patients. Bilirubinostasis, severe fibrosis and ductular reaction were prominent features of AH. AH patients exhibited a more profound deregulation of gene expression compared with ndALD patients.

Ductular reaction promotes intrahepatic angiogenesis through Slit2-Roundabout 1 signaling.

BACKGROUND AND AIMS: Ductular reaction (DR) expands in chronic liver diseases and correlates with disease severity. Besides its potential role in liver regeneration, DR plays a role in the wound-healing response of the liver, promoting periductular fibrosis and inflammatory cell recruitment. However, there is no information regarding its role in intrahepatic angiogenesis. In the current study we investigated the potential contribution of DR cells to hepatic vascular remodeling during chronic liver disease. APPROACH AND RESULTS: In mouse models of liver injury, DR cells express genes involved in angiogenesis. Among angiogenesis-related genes, the expression of Slit2 and its receptor Roundabout 1 (Robo1) was localized in DR cells and neoangiogenic vessels, respectively. The angiogenic role of the Slit2-Robo1 pathway in chronic liver disease was confirmed in ROBO1/2-/+ mice treated with 3,5-diethoxycarbonyl-1,4-dihydrocollidine, which displayed reduced intrahepatic neovascular density compared to wild-type mice. However, ROBO1/2 deficiency did not affect angiogenesis in partial hepatectomy. In patients with advanced alcohol-associated disease, angiogenesis was associated with DR, and up-regulation of SLIT2-ROBO1 correlated with DR and disease severity. In vitro, human liver-derived organoids produced SLIT2 and induced tube formation of endothelial cells. CONCLUSIONS: Overall, our data indicate that DR expansion promotes angiogenesis through the Slit2-Robo1 pathway and recognize DR cells as key players in the liver wound-healing response.

Loss of hepatocyte identity following aberrant YAP activation: A key mechanism in alcoholic hepatitis.

BACKGROUND & AIMS: Alcoholic hepatitis (AH) is a life-threatening disease with limited therapeutic options, as the molecular mechanisms leading to death are not well understood. This study evaluates the Hippo/Yes-associated protein (YAP) pathway which has been shown to play a role in liver regeneration. METHOD: The Hippo/YAP pathway was dissected in explants of patients transplanted for AH or alcohol-related cirrhosis and in control livers, using RNA-seq, real-time PCR, western blot, immunohistochemistry and transcriptome analysis after laser microdissection. We transfected primary human hepatocytes with constitutively active YAP (YAPS127A) and treated HepaRG cells and primary hepatocytes isolated from AH livers with a YAP inhibitor. We also used mouse models of ethanol exposure (Lieber de Carli) and liver regeneration (carbon tetrachloride) after hepatocyte transduction of YAPS127A. RESULTS: In AH samples, RNA-seq analysis and immunohistochemistry of total liver and microdissected hepatocytes revealed marked downregulation of the Hippo pathway, demonstrated by lower levels of active MST1 kinase and abnormal activation of YAP in hepatocytes. Overactivation of YAP in hepatocytes in vitro and in vivo led to biliary differentiation and loss of key biological functions such as regeneration capacity. Conversely, a YAP inhibitor restored the mature hepatocyte phenotype in abnormal hepatocytes taken from patients with AH. In ethanol-fed mice, YAP activation using YAPS127A resulted in a loss of hepatocyte differentiation. Hepatocyte proliferation was hampered by YAPS127A after carbon tetrachloride intoxication. CONCLUSION: Aberrant activation of YAP plays an important role in hepatocyte transdifferentiation in AH, through a loss of hepatocyte identity and impaired regeneration. Thus, targeting YAP is a promising strategy for the treatment of patients with AH. LAY SUMMARY: Alcoholic hepatitis is characterized by inflammation and a life-threatening alteration of liver regeneration, although the mechanisms behind this have not been identified. Herein, we show that liver samples from patients with alcoholic hepatitis are characterized by profound deregulation of the Hippo/YAP pathway with uncontrolled activation of YAP in hepatocytes. We used human cell and mouse models to show that inhibition of YAP reverts this hepatocyte defect and could be a novel therapeutic strategy for alcoholic hepatitis.