RACK1 controls IRES-mediated translation of viruses.

Fighting viral infections is hampered by the scarcity of viral targets and their variability, resulting in development of resistance. Viruses depend on cellular molecules-which are attractive alternative targets-for their life cycle, provided that they are dispensable for normal cell functions. Using the model organism Drosophila melanogaster, we identify the ribosomal protein RACK1 as a cellular factor required for infection by internal ribosome entry site (IRES)-containing viruses. We further show that RACK1 is an essential determinant for hepatitis C virus translation and infection, indicating that its function is conserved for distantly related human and fly viruses. Inhibition of RACK1 does not affect Drosophila or human cell viability and proliferation, and RACK1-silenced adult flies are viable, indicating that this protein is not essential for general translation. Our findings demonstrate a specific function for RACK1 in selective mRNA translation and uncover a target for the development of broad antiviral intervention.

JAK1 promotes HDV replication and is a potential target for antiviral therapy.

BACKGROUND & AIMS: Chronic co-infection with HBV and HDV leads to the most aggressive form of chronic viral hepatitis. To date, no treatment induces efficient viral clearance, and a better characterization of virus-host interactions is required to develop new therapeutic strategies. METHODS: Using loss-of-function strategies, we validated the unexpected proviral activity of Janus kinase 1 (JAK1) - a key player in innate immunity - in the HDV life cycle and determined its mechanism of action on HDV through various functional analyses including co-immunoprecipitation assays. RESULTS: We confirmed the key role of JAK1 kinase activity in HDV infection. Moreover, our results suggest that JAK1 inhibition is associated with a modulation of ERK1/2 activation and S-HDAg phosphorylation, which is crucial for viral replication. Finally, we showed that FDA-approved JAK1-specific inhibitors are efficient antivirals in relevant in vitro models including primary human hepatocytes. CONCLUSIONS: Taken together, we uncovered JAK1 as a key host factor for HDV replication and a potential target for new antiviral treatment. IMPACT AND IMPLICATIONS: Chronic hepatitis D is the most aggressive form of chronic viral hepatitis. As no curative treatment is currently available, new therapeutic strategies based on host-targeting agents are urgently needed. Here, using loss-of-function strategies, we uncover an unexpected interaction between JAK1, a major player in the innate antiviral response, and HDV infection. We demonstrated that JAK1 kinase activity is crucial for both the phosphorylation of the delta antigen and the replication of the virus. By demonstrating the antiviral potential of several FDA-approved JAK1 inhibitors, our results could pave the way for the development of innovative therapeutic strategies to tackle this global health threat.

Prognostic benefit of preoperative transarterial chemoembolization in upfront resectable large hepatocellular carcinoma: a multicentric propensity score based analysis of European high-volume centers.

BACKGROUND: Hepatocellular carcinoma (HCC) have a dismal prognosis and any effective neoadjuvant treatment has been validated to date. We aimed to investigate the role of neoadjuvant transarterial chemoembolization (TACE) in upfront resectable HCC larger than 5 cm. METHODS: This is a multicentric retrospective study comparing outcomes of large HCC undergoing TACE followed by surgery or liver resection alone before and after propensity-score matching (PSM). RESULTS: A total of 384 patients were included of whom 60 (15.6%) received TACE. This group did not differ from upfront resected cases neither in terms of disease-free survival (p = 0.246) nor in overall survival (p = 0.276). After PSM, TACE still did not influence long-term outcomes (p = 0.935 and p = 0.172, for DFS and OS respectively). In subgroup analysis, TACE improved OS only in HCC ≥10 cm (p = 0.045), with a borderline significance after portal vein embolization/ligation (p = 0.087) and in single HCC (p = 0.052). CONCLUSIONS: TACE should not be systematically performed in all resectable large HCC. Selected cases could however potentially benefit from this procedure, as patients with huge and single tumors or those necessitating of a PVE.

Treatment of HCC with claudin-1-specific antibodies suppresses carcinogenic signaling and reprograms the tumor microenvironment.

BACKGROUND & AIMS: Despite recent approvals, the response to treatment and prognosis of patients with advanced hepatocellular carcinoma (HCC) remain poor. Claudin-1 (CLDN1) is a membrane protein that is expressed at tight junctions, but it can also be exposed non-junctionally, such as on the basolateral membrane of the human hepatocyte. While CLDN1 within tight junctions is well characterized, the role of non-junctional CLDN1 and its role as a therapeutic target in HCC remains unexplored. METHODS: Using humanized monoclonal antibodies (mAbs) specifically targeting the extracellular loop of human non-junctional CLDN1 and a large series of patient-derived cell-based and animal model systems we aimed to investigate the role of CLDN1 as a therapeutic target for HCC. RESULTS: Targeting non-junctional CLDN1 markedly suppressed tumor growth and invasion in cell line-based models of HCC and patient-derived 3D ex vivo models. Moreover, the robust effect on tumor growth was confirmed in vivo in a large series of cell line-derived xenograft and patient-derived xenograft mouse models. Mechanistic studies, including single-cell RNA sequencing of multicellular patient HCC tumorspheres, suggested that CLDN1 regulates tumor stemness, metabolism, oncogenic signaling and perturbs the tumor immune microenvironment. CONCLUSIONS: Our results provide the rationale for targeting CLDN1 in HCC and pave the way for the clinical development of CLDN1-specific mAbs for the treatment of advanced HCC. IMPACT AND IMPLICATIONS: Hepatocellular carcinoma (HCC) is associated with high mortality and unsatisfactory treatment options. Herein, we identified the cell surface protein Claudin-1 as a treatment target for advanced HCC. Monoclonal antibodies targeting Claudin-1 inhibit tumor growth in patient-derived ex vivo and in vivo models by modulating signaling, cell stemness and the tumor immune microenvironment. Given the differentiated mechanism of action, the identification of Claudin-1 as a novel therapeutic target for HCC provides an opportunity to break the plateau of limited treatment response. The results of this preclinical study pave the way for the clinical development of Claudin-1-specific antibodies for the treatment of advanced HCC. It is therefore of key impact for physicians, scientists and drug developers in the field of liver cancer and gastrointestinal oncology.

Combining Radiofrequency Ablation with Hepatic Resection for Liver-Only Colorectal Metastases: A Propensity-Score Based Analysis of Long-Term Outcomes.

BACKGROUND: Combining liver resection (LR) with radiofrequency ablation (RFA) is nowadays an accepted option for treating colorectal liver metastases (CRLMs), but the number of lesions ablated is regularly described as a recurrence risk factor. In this study, we report our experience and determine the impact of RFA on long-term outcomes. METHOD: This is a retrospective study including patients undergoing LR with or without RFA for CRLM. All variables influencing disease-free survival (DFS) and disease-specific survival (DSS) were examined through a Cox regression analysis before and after propensity-score matching (PSM). RESULTS: Among the 128 patients included, 71 (55.5%) underwent LR alone and 57 (44.5%) underwent LR+RFA. With univariate analysis, LR+RFA showed a significantly worse DFS than LR alone (p = 0.028), which was not confirmed after PSM (p = 0.064). Thermal ablation did not influence DSS before or after matching (p = 0.282 and p = 0.189). When analyzing the subgroups of patients according to number of RFAs performed, no difference in long-term outcomes was observed (after PSM: p = 0.192 for DFS and p = 0.624 for DSS). Analysis of site of recurrence revealed that neither performing an RFA (p = 0.893) nor the number of lesions ablated (p = 0.093, p = 0.550, and p = 0.087 for 1, 2, and ≥ 2 RFAs) were associated with an increased risk of liver-only relapse. DISCUSSION: In the setting of a parenchymal sparing strategy, combining RFA with LR is safe in terms of oncological outcomes. Tumor burden, rather than RFA performed, independently influences risk of recurrence and patient survival.

Paradigm shift: should preoperative 3D reconstruction models become mandatory before hepatectomy for hepatocellular carcinoma (HCC)? Results of a multicenter prospective trial.

BACKGROUND: A preoperative surgical strategy before hepatectomy for hepatocellular carcinoma is fundamental to minimize postoperative morbidity and mortality and to reach the best oncologic outcomes. Preoperative 3D reconstruction models may help to better choose the type of procedure to perform and possibly change the initially established plan based on conventional 2D imaging. METHODS: A non-randomized multicenter prospective trial with 136 patients presenting with a resectable hepatocellular carcinoma who underwent open or minimally invasive liver resection. Measurement was based on the modification rate analysis between conventional 2D imaging (named "Plan A") and 3D model analysis ("Plan B"), and from Plan B to the final procedure performed (named "Plan C"). RESULTS: The modification rate from Plan B to Plan C (18%) was less frequent than the modification from Plan A to Plan B (35%) (OR = 0.32 [0.15; 0.64]). Concerning secondary objectives, resection margins were underestimated in Plan B as compared to Plan C (-3.10 mm [-5.04; -1.15]). CONCLUSION: Preoperative 3D imaging is associated with a better prediction of the performed surgical procedure for liver resections in HCC, as compared to classical 2D imaging.

Cell-based cccDNA reporter assay combined with functional genomics identifies YBX1 as HBV cccDNA host factor and antiviral candidate target.

OBJECTIVES: Chronic hepatitis B virus (HBV) infection is a leading cause of liver disease and hepatocellular carcinoma. A key feature of HBV replication is the synthesis of the covalently close circular (ccc)DNA, not targeted by current treatments and whose elimination would be crucial for viral cure. To date, little is known about cccDNA formation. One major challenge to address this urgent question is the absence of robust models for the study of cccDNA biology. DESIGN: We established a cell-based HBV cccDNA reporter assay and performed a loss-of-function screen targeting 239 genes encoding the human DNA damage response machinery. RESULTS: Overcoming the limitations of current models, the reporter assay enables to quantity cccDNA levels using a robust ELISA as a readout. A loss-of-function screen identified 27 candidate cccDNA host factors, including Y box binding protein 1 (YBX1), a DNA binding protein regulating transcription and translation. Validation studies in authentic infection models revealed a robust decrease in HBV cccDNA levels following silencing, providing proof-of-concept for the importance of YBX1 in the early steps of the HBV life cycle. In patients, YBX1 expression robustly correlates with both HBV load and liver disease progression. CONCLUSION: Our cell-based reporter assay enables the discovery of HBV cccDNA host factors including YBX1 and is suitable for the characterisation of cccDNA-related host factors, antiviral targets and compounds.

Targeting clinical epigenetic reprogramming for chemoprevention of metabolic and viral hepatocellular carcinoma.

OBJECTIVE: Hepatocellular carcinoma (HCC) is the fastest-growing cause of cancer-related mortality with chronic viral hepatitis and non-alcoholic steatohepatitis (NASH) as major aetiologies. Treatment options for HCC are unsatisfactory and chemopreventive approaches are absent. Chronic hepatitis C (CHC) results in epigenetic alterations driving HCC risk and persisting following cure. Here, we aimed to investigate epigenetic modifications as targets for liver cancer chemoprevention. DESIGN: Liver tissues from patients with NASH and CHC were analysed by ChIP-Seq (H3K27ac) and RNA-Seq. The liver disease-specific epigenetic and transcriptional reprogramming in patients was modelled in a liver cell culture system. Perturbation studies combined with a targeted small molecule screen followed by in vivo and ex vivo validation were used to identify chromatin modifiers and readers for HCC chemoprevention. RESULTS: In patients, CHC and NASH share similar epigenetic and transcriptomic modifications driving cancer risk. Using a cell-based system modelling epigenetic modifications in patients, we identified chromatin readers as targets to revert liver gene transcription driving clinical HCC risk. Proof-of-concept studies in a NASH-HCC mouse model showed that the pharmacological inhibition of chromatin reader bromodomain 4 inhibited liver disease progression and hepatocarcinogenesis by restoring transcriptional reprogramming of the genes that were epigenetically altered in patients. CONCLUSION: Our results unravel the functional relevance of metabolic and virus-induced epigenetic alterations for pathogenesis of HCC development and identify chromatin readers as targets for chemoprevention in patients with chronic liver diseases.

Laparoscopic anatomical liver resection for malignancies using positive or negative staining technique with intraoperative indocyanine green-fluorescence imaging.

BACKGROUND: Indications for a minimally invasive resections are increasing worldwide, but respecting anatomical planes during intraparenchymal transection is demanding. Intraoperative ICG fluorescence staining of liver parenchyma has been introduced as a tool for real-time intraoperative guidance. The aim of this study is to make a systematic review of the current relevant literature on indications, techniques, and results of laparoscopic anatomical liver resection (LALR) using intraoperative indocyanine green (ICG) fluorescence for positive and negative staining of liver segments in patients affected by liver malignancies. METHODS: Electronic bibliographical databases (MEDLINE and PubMed) were searched according to the PRISMA criteria. English language articles meeting the selection criteria and published until June 2020 were retrieved and reviewed. RESULTS: a total of 86 articles were initially found and 11 articles were finally included in the analysis with a total of 83 patients treated. Sixty-two patients (74.6%) underwent mono-segmentectomies. Thirty-five patients (42.1%) underwent the positive staining technique, and forty-eight patients (57.8%) the negative staining technique. CONCLUSIONS: The positive or negative indocyanine green staining technique with real-time fluorescence guidance is an emerging and promising approach. However, the technique has to be standardized and advantages in terms of oncologic results still need validation in further studies.

Combined small molecule and loss-of-function screen uncovers estrogen receptor alpha and CAD as host factors for HDV infection and antiviral targets.

OBJECTIVE: Hepatitis D virus (HDV) is a circular RNA virus coinfecting hepatocytes with hepatitis B virus. Chronic hepatitis D results in severe liver disease and an increased risk of liver cancer. Efficient therapeutic approaches against HDV are absent. DESIGN: Here, we combined an RNAi loss-of-function and small molecule screen to uncover host-dependency factors for HDV infection. RESULTS: Functional screening unravelled the hypoxia-inducible factor (HIF)-signalling and insulin-resistance pathways, RNA polymerase II, glycosaminoglycan biosynthesis and the pyrimidine metabolism as virus-hepatocyte dependency networks. Validation studies in primary human hepatocytes identified the carbamoyl-phosphatesynthetase 2, aspartate transcarbamylase and dihydroorotase (CAD) enzyme and estrogen receptor alpha (encoded by ESR1) as key host factors for HDV life cycle. Mechanistic studies revealed that the two host factors are required for viral replication. Inhibition studies using N-(phosphonoacetyl)-L-aspartic acid and fulvestrant, specific CAD and ESR1 inhibitors, respectively, uncovered their impact as antiviral targets. CONCLUSION: The discovery of HDV host-dependency factors elucidates the pathogenesis of viral disease biology and opens therapeutic strategies for HDV cure.

HCV-Induced Epigenetic Changes Associated With Liver Cancer Risk Persist After Sustained Virologic Response.

BACKGROUND & AIMS: Chronic hepatitis C virus (HCV) infection is an important risk factor for hepatocellular carcinoma (HCC). Despite effective antiviral therapies, the risk for HCC is decreased but not eliminated after a sustained virologic response (SVR) to direct-acting antiviral (DAA) agents, and the risk is higher in patients with advanced fibrosis. We investigated HCV-induced epigenetic alterations that might affect risk for HCC after DAA treatment in patients and mice with humanized livers. METHODS: We performed genome-wide ChIPmentation-based ChIP-Seq and RNA-seq analyses of liver tissues from 6 patients without HCV infection (controls), 18 patients with chronic HCV infection, 8 patients with chronic HCV infection cured by DAA treatment, 13 patients with chronic HCV infection cured by interferon therapy, 4 patients with chronic hepatitis B virus infection, and 7 patients with nonalcoholic steatohepatitis in Europe and Japan. HCV-induced epigenetic modifications were mapped by comparative analyses with modifications associated with other liver disease etiologies. uPA/SCID mice were engrafted with human hepatocytes to create mice with humanized livers and given injections of HCV-infected serum samples from patients; mice were given DAAs to eradicate the virus. Pathways associated with HCC risk were identified by integrative pathway analyses and validated in analyses of paired HCC tissues from 8 patients with an SVR to DAA treatment of HCV infection. RESULTS: We found chronic HCV infection to induce specific genome-wide changes in H3K27ac, which correlated with changes in expression of mRNAs and proteins. These changes persisted after an SVR to DAAs or interferon-based therapies. Integrative pathway analyses of liver tissues from patients and mice with humanized livers demonstrated that HCV-induced epigenetic alterations were associated with liver cancer risk. Computational analyses associated increased expression of SPHK1 with HCC risk. We validated these findings in an independent cohort of patients with HCV-related cirrhosis (n = 216), a subset of which (n = 21) achieved viral clearance. CONCLUSIONS: In an analysis of liver tissues from patients with and without an SVR to DAA therapy, we identified epigenetic and gene expression alterations associated with risk for HCC. These alterations might be targeted to prevent liver cancer in patients treated for HCV infection.

Interferon-Induced Transmembrane Proteins Mediate Viral Evasion in Acute and Chronic Hepatitis C Virus Infection.

Although adaptive immune responses against hepatitis C virus (HCV) infection have been studied in great detail, the role of innate immunity in protection against HCV infection and immune evasion is only partially understood. Interferon-induced transmembrane proteins (IFITMs) are innate effector proteins restricting host cell entry of many enveloped viruses, including HCV. However, the clinical impact of IFITMs on HCV immune escape remains to be determined. Here, we show that IFITMs promote viral escape from the neutralizing antibody (nAb) response in clinical cohorts of HCV-infected patients. Using pseudoparticles bearing HCV envelope proteins from acutely infected patients, we show that HCV variants isolated preseroconversion are more sensitive to the antiviral activity of IFITMs than variants from patients isolated during chronic infection postseroconversion. Furthermore, HCV variants escaping nAb responses during liver transplantation exhibited a significantly higher resistance to IFITMs than variants that were eliminated posttransplantation. Gain-of-function and mechanistic studies revealed that IFITMs markedly enhance the antiviral activity of nAbs and suggest a cooperative effect of human monoclonal antibodies and IFITMs for antibody-mediated neutralization driving the selection pressure in viral evasion. Perturbation studies with the IFITM antagonist amphotericin B revealed that modulation of membrane properties by IFITM proteins is responsible for the IFITM-mediated blockade of viral entry and enhancement of antibody-mediated neutralization. Conclusion: Our results indicate IFITM proteins as drivers of viral immune escape and antibody-mediated HCV neutralization in acute and chronic HCV infection. These findings are of clinical relevance for the design of urgently needed HCV B-cell vaccines and might help to increase the efficacy of future vaccine candidates.

Tight Junction Proteins and the Biology of Hepatobiliary Disease.

Tight junctions (TJ) are intercellular adhesion complexes on epithelial cells and composed of integral membrane proteins as well as cytosolic adaptor proteins. Tight junction proteins have been recognized to play a key role in health and disease. In the liver, TJ proteins have several functions: they contribute as gatekeepers for paracellular diffusion between adherent hepatocytes or cholangiocytes to shape the blood-biliary barrier (BBIB) and maintain tissue homeostasis. At non-junctional localizations, TJ proteins are involved in key regulatory cell functions such as differentiation, proliferation, and migration by recruiting signaling proteins in response to extracellular stimuli. Moreover, TJ proteins are hepatocyte entry factors for the hepatitis C virus (HCV)-a major cause of liver disease and cancer worldwide. Perturbation of TJ protein expression has been reported in chronic HCV infection, cholestatic liver diseases as well as hepatobiliary carcinoma. Here we review the physiological function of TJ proteins in the liver and their implications in hepatobiliary diseases.

Hepatitis B Virus Evasion From Cyclic Guanosine Monophosphate-Adenosine Monophosphate Synthase Sensing in Human Hepatocytes.

Chronic hepatitis B virus (HBV) infection is a major cause of chronic liver disease and cancer worldwide. The mechanisms of viral genome sensing and the evasion of innate immune responses by HBV infection are still poorly understood. Recently, the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) was identified as a DNA sensor. In this study, we investigated the functional role of cGAS in sensing HBV infection and elucidate the mechanisms of viral evasion. We performed functional studies including loss-of-function and gain-of-function experiments combined with cGAS effector gene expression profiling in an infectious cell culture model, primary human hepatocytes, and HBV-infected human liver chimeric mice. Here, we show that cGAS is expressed in the human liver, primary human hepatocytes, and human liver chimeric mice. While naked relaxed-circular HBV DNA is sensed in a cGAS-dependent manner in hepatoma cell lines and primary human hepatocytes, host cell recognition of viral nucleic acids is abolished during HBV infection, suggesting escape from sensing, likely during packaging of the genome into the viral capsid. While the hepatocyte cGAS pathway is functionally active, as shown by reduction of viral covalently closed circular DNA levels in gain-of-function studies, HBV infection suppressed cGAS expression and function in cell culture models and humanized mice. Conclusion: HBV exploits multiple strategies to evade sensing and antiviral activity of cGAS and its effector pathways.

The functional role of sodium taurocholate cotransporting polypeptide NTCP in the life cycle of hepatitis B, C and D viruses.

Chronic hepatitis B, C and D virus (HBV, HCV and HDV) infections are a major cause of liver disease and cancer worldwide. Despite employing distinct replication strategies, the three viruses are exclusively hepatotropic, and therefore depend on hepatocyte-specific host factors. The sodium taurocholate co-transporting polypeptide (NTCP), a transmembrane protein highly expressed in human hepatocytes that mediates the transport of bile acids, plays a key role in HBV and HDV entry into hepatocytes. Recently, NTCP has been shown to modulate HCV infection of hepatocytes by regulating innate antiviral immune responses in the liver. Here, we review the current knowledge of the functional role and the molecular and cellular biology of NTCP in the life cycle of the three major hepatotropic viruses, highlight the impact of NTCP as an antiviral target and discuss future avenues of research.

[Hepatitis D virus: viral cycle and new therapeutic approaches]. / Virus de l'hépatite D : cycle viral et nouvelles stratégies thérapeutiques.

An estimated 70 million people are chronically infected with hepatitis D (delta) virus (HDV) worldwide. HDV is a small satellite virus of hepatitis B virus (HBV) requiring HBV for the completion of its cycle. Hepatitis D is the most severe form of chronic viral hepatitis. It is responsible for an acceleration and an aggravation of chronic liver disease compared to HBV monoinfected patients. Current treatments based on pegylated interferon rarely allow viral clearance in chronically infected patients. For long time, the absence of easy-to-use models has limited the knowledge on virus-host interactions. Notably, hepatocyte host factors involved in the viral life cycle remain largely unknown. These host factors are potential therapeutic targets for novel treatment strategies, including molecules currently evaluated in clinical trials. This review summarizes our knowledge on HDV molecular virology and innovative therapeutic strategies targeting hepatocyte host factors.