Deep mutational scanning of hepatitis B virus reveals a mechanism for cis-preferential reverse transcription

Hepatitis B virus (HBV) is a small double-stranded DNA virus that chronically infects 296 million people. Over half of its compact genome encodes proteins in two overlapping reading frames, and during evolution, multiple selective pressures can act on shared nucleotides. This study combines an RNA-based HBV cell culture system with deep mutational scanning (DMS) to uncouple cis- and trans-acting sequence requirements in the HBV genome. The results support a leaky ribosome scanning model for polymerase translation, provide a fitness map of the HBV polymerase at single-nucleotide resolution, and identify conserved prolines adjacent to the HBV polymerase termination codon that stall ribosomes. Further experiments indicated that stalled ribosomes tether the nascent polymerase to its template RNA, ensuring cis-preferential RNA packaging and reverse transcription of the HBV genome.

A decision-making model for prediction of a stable disease course in chronic hepatitis B patients

Patients with chronic hepatitis B (CHB) are regularly monitored for HBV DNA and liver enzymes in order to assess disease progression and the need for antiviral therapy. Identifying patients with a stable course of disease can potentially prolong the intervals between visits, withhold unnecessary tests and save money. Accordingly, we aimed to find predictors for a stable disease course in patients with CHB. 579 patients with CHB, who were followed in a tertiary referral center between January 2004-December 2018, were retrospectively analyzed. Patients with low and steady viral load titer (< 2000 IU/ml) and normal ALT levels (< 40 IU/ml) in 6 consecutive clinic encounters were considered to have a stable course of CHB. A stepwise multivariate logistic regression analysis and a decision tree model were used to identify predictors of a stable disease course. Following exclusion of ineligible patients, a total of 220 patients were included in the final analysis. 64/220 patients had a stable disease course. Patients with a stable disease were older (62.99 ± 12.36 Vs. 54.07 ± 13.64, p < 0.001) with a higher percentage of women (53% vs. 38%) and had lower baseline levels of AST, ALT and viral load (VL). In a multivariate analysis, age (OR 0.94, 95% CI 0.91-0.98), baseline ALT (OR 1.06, 95% CI 1.01-1.1) and VL (OR 1.05 95% CI 1.02-1.08), were significantly associated with a stable disease. In a decision tree model, patients 46-67 years old, with baseline VL < 149 IU/mL and ALT < 40 IU/mL had the best probability (91%) for a stable disease course over 4.4 ± 2.2 years. We conclude that integrating patients' age with baseline VL and ALT can predict a stable disease course in patients with CHB off treatment.

An RNA-based system to study hepatitis B virus replication and evaluate antivirals

Hepatitis B virus (HBV) chronically infects an estimated 300 million people, and standard treatments are rarely curative. Infection increases the risk of liver cirrhosis and hepatocellular carcinoma, and consequently, nearly 1 million people die each year from chronic hepatitis B. Tools and approaches that bring insights into HBV biology and facilitate the discovery and evaluation of antiviral drugs are in demand. Here, we describe a method to initiate the replication of HBV, a DNA virus, using synthetic RNA. This approach eliminates contaminating background signals from input virus or plasmid DNA that plagues existing systems and can be used to study multiple stages of HBV replication. We further demonstrate that this method can be uniquely applied to identify sequence variants that confer resistance to antiviral drugs.

Immunogenicity of a Third Dose of BNT162b2 Vaccine among Lung Transplant Recipients—A Prospective Cohort Study

Two doses of mRNA SARS-CoV-2 vaccines elicit an attenuated humoral immune response among immunocompromised patients. Our study aimed to assess the immunogenicity of a third dose of the BNT162b2 vaccine among lung transplant recipients (LTRs). We prospectively evaluated the humoral response by measuring anti-spike SARS-CoV-2 and neutralizing antibodies in 139 vaccinated LTRs ~4–6 weeks following the third vaccine dose. The t-cell response was evaluated by IFNγ assay. The primary outcome was the seropositivity rate following the third vaccine dose. Secondary outcomes included: positive neutralizing antibody and cellular immune response rate, adverse events, and COVID-19 infections. Results were compared to a control group of 41 healthcare workers. Among LTRs, 42.4% had a seropositive antibody titer, and 17.2% had a positive t-cell response. Seropositivity was associated with younger age (t = 3.736, p < 0.001), higher GFR (t = 2.355, p = 0.011), and longer duration from transplantation (t = −1.992, p = 0.024). Antibody titer positively correlated with neutralizing antibodies (r = 0.955, p < 0.001). The current study may suggest the enhancement of immunogenicity by using booster doses. Since monoclonal antibodies have limited effectiveness against prevalent sub-variants and LTRs are prone to severe COVID-19 morbidity, vaccination remains crucial for this vulnerable population.

Elevated Serum Amyloid A Levels Contribute to Increased Platelet Adhesion in COVID-19 Patients

Coronavirus disease-19 (COVID-19) patients are prone to thrombotic complications that may increase morbidity and mortality. These complications are thought to be driven by endothelial activation and tissue damage promoted by the systemic hyperinflammation associated with COVID-19. However, the exact mechanisms contributing to these complications are still unknown. To identify additional mechanisms contributing to the aberrant clotting observed in COVID-19 patients, we analyzed platelets from COVID-19 patients compared to those from controls using mass spectrometry. We identified increased serum amyloid A (SAA) levels, an acute-phase protein, on COVID-19 patients' platelets. In addition, using an in vitro adhesion assay, we showed that healthy platelets adhered more strongly to wells coated with COVID-19 patient serum than to wells coated with control serum. Furthermore, inhibitors of integrin aIIbβ3 receptors, a mediator of platelet-SAA binding, reduced platelet adhesion to recombinant SAA and to wells coated with COVID-19 patient serum. Our results suggest that SAA may contribute to the increased platelet adhesion observed in serum from COVID-19 patients. Thus, reducing SAA levels by decreasing inflammation or inhibiting SAA platelet-binding activity might be a valid approach to abrogate COVID-19-associated thrombotic complications.

Steatosis, HBV-related HCC, cirrhosis, and HBsAg seroclearance: A systematic review and meta-analysis

BACKGROUND AND AIMS

NAFLD and chronic hepatitis B (CHB) infection are common etiologies of HCC. The impact of hepatic steatosis on HCC in CHB, as well as its relationship with the development of cirrhosis, fibrosis, and HBsAg seroclearance, remains controversial.

APPROACH AND RESULTS

Data from observational studies were collected through PubMed, EMBASE, and the Cochrane Library from inception to February 1, 2022. Outcomes of interest included the association of hepatic steatosis with HCC, cirrhosis, advanced fibrosis, and HBsAg seroclearance, expressed in terms of pooled ORs. Additional subgroup and sensitivity analyses were performed to validate the robustness of findings. A total of 34 studies with 68,268 patients with CHB were included. Hepatic steatosis was associated with higher odds of HCC (OR, 1.59; 95% CI, 1.12-2.26; I²  = 72.5%), with the association remaining consistent in Asia (OR, 1.56; 95% CI, 1.08-2.25), studies with a median follow-up duration of ≥5 years (OR, 2.82; 95% CI, 1.57-5.08), exclusion of alcohol use (OR, 1.71; 95% CI, 1.01-2.91), and biopsy-proven steatosis (OR, 2.86; 95% CI, 1.61-5.06), although no significant association was noted among nucleos(t)ide analogue-treated patients (OR, 1.05; 95% CI, 0.62-1.77). Steatosis was associated with the development of cirrhosis (OR, 1.52; 95% CI, 1.07-2.16; I²  = 0%) and HBsAg seroclearance (OR, 2.22; 95% CI, 1.58-3.10; I²  = 49.0%).

CONCLUSIONS

Hepatic steatosis was associated with an increased risk of HCC and cirrhosis among patients with CHB but with a higher chance of achieving a functional cure, highlighting the importance of identifying concomitant steatosis in CHB.

Modeling-Based Response-Guided DAA Therapy for Chronic Hepatitis C to Identify Individuals for Shortening Treatment Duration

Shortening duration of direct-acting antiviral therapy for chronic hepatitis C could provide cost savings, reduce medication exposure, and foster adherence and treatment completion in special populations. The current analysis indicates that measuring hepatitis C virus at baseline and on days 7 and 14 of therapy can identify patients for shortening therapy duration.

A genome-wide CRISPR activation screen reveals Hexokinase 1 as a critical factor in promoting resistance to multi-kinase inhibitors in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is often diagnosed at an advanced stage and is, therefore, treated with systemic drugs, such as tyrosine-kinase inhibitors (TKIs). These drugs, however, offer only modest survival benefits due to the rapid development of drug resistance. To identify genes implicated in TKI resistance, a cluster of regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 activation screen was performed in hepatoma cells treated with regorafenib, a TKI used as second-line therapy for advanced HCC. The screen results show that Hexokinase 1 (HK1), catalyzing the first step in glucose metabolism, is a top candidate for conferring TKI resistance. Compatible with this, HK1 was upregulated in regorafenib-resistant cells. Using several experimental approaches, both in vitro and in vivo, we show that TKI resistance correlates with HK1 expression. Furthermore, an HK inhibitor resensitized resistant cells to TKI treatment. Together, our data indicate that HK1 may function as a critical factor modulating TKI resistance in hepatoma cells and, therefore, may serve as a biomarker for treatment success.

Machine learning for mathematical models of HCV kinetics during antiviral therapy

Mathematical models for hepatitis C virus (HCV) dynamics have provided a means for evaluating the antiviral effectiveness of therapy and estimating treatment outcomes such as the time to cure. Recently, a mathematical modeling approach was used in the first proof-of-concept clinical trial assessing in real-time the utility of response-guided therapy with direct-acting antivirals (DAAs) in chronic HCV-infected patients. Several retrospective studies have shown that mathematical modeling of viral kinetics predicts time to cure of less than 12 weeks in the majority of individuals treated with sofosbuvir-based as well as other DAA regimens. A database of these studies was built, and machine learning methods were evaluated for their ability to estimate the time to cure for each patient to facilitate real-time modeling studies. Data from these studies exploring mathematical modeling of HCV kinetics under DAAs in 266 chronic HCV-infected patients were gathered. Different learning methods were applied and trained on part of the dataset ('train' set), to predict time to cure on the untrained part ('test' set). Our results show that this machine learning approach provides a means for establishing an accurate time to cure prediction that will support the implementation of individualized treatment.

Early post-liver transplantation infections and their effect on long-term survival

BACKGROUND

Infections post-liver transplantation are major drivers for morbidity and mortality. However, the impact of infections within 180 days post-liver transplantation on long-term survival is not clear.

METHODS

We present a retrospective cohort of 317 liver transplant patients for whom all infectious episodes were prospectively collected during a mean follow-up of 4.4 years.

RESULTS

A total of 143/317 (45%) of patients suffered from any infectious episode during the first 6 months following liver transplantation. Patients with surgical site infections have a reduced survival compared to those with no infection (HR 0.33, 95% CI 0.172-0.636, P = .001), whereas infections from other sources, including pneumonia, UTI, and line-related infections, were not associated with increased mortality. Furthermore, even though the presence of any infection within 30 days or 6 months post-transplantation did not affect survival, more than a single infectious episode per patient was significantly associated with increased mortality (HR 1.70, CI 1.12-2.60, P = .013). In a multivariate analysis, the number of infectious episodes remained statistically significant (HR 1.58, 95% CI 1.03-2.43, P = .035) upon adjustment for other major variables associated with comorbidities and infection risk.

CONCLUSIONS

Surgical site infections and the number of infectious episodes within 180 days post-liver transplantation are major determinants of long-term survival among these patients.

Secondary bacterial infection in COVID-19 patients is a stronger predictor for death compared to influenza patients

Secondary bacterial infections are a potentially fatal complication of influenza infection. We aimed to define the impact of secondary bacterial infections on the clinical course and mortality in coronavirus disease 2019 (COVID-19) patients by comparison with influenza patients. COVID-19 (n = 642) and influenza (n = 742) patients, admitted to a large tertiary center in Israel and for whom blood or sputum culture had been taken were selected for this study. Bacterial culture results, clinical parameters, and death rates were compared. COVID-19 patients had higher rates of bacterial infections than influenza patients (12.6% vs. 8.7%). Notably, the time from admission to bacterial growth was longer in COVID-19 compared to influenza patients (4 (1-8) vs. 1 (1-3) days). Late infections (> 48 h after admission) with gram-positive bacteria were more common in COVID-19 patients (28% vs. 9.5%). Secondary infection was associated with a higher risk of death in both patient groups 2.7-fold (1.22-5.83) for COVID-19, and 3.09-fold (1.11-7.38) for Influenza). The association with death remained significant upon adjustment to age and clinical parameters in COVID-19 but not in influenza infection. Secondary bacterial infection is a notable complication associated with worse outcomes in COVID-19 than influenza patients. Careful surveillance and prompt antibiotic treatment may benefit selected patients.

Modeling Social Distancing Strategies to Prevent SARS-CoV-2 Spread in Israel: A Cost-Effectiveness Analysis

OBJECTIVES

While highly effective in preventing SARS-CoV-2 spread, national lockdowns come with an enormous economic price. Few countries have adopted an alternative "testing, tracing, and isolation" approach to selectively isolate people at high exposure risk, thereby minimizing the economic impact. To assist policy makers, we performed a cost-effectiveness analysis of these 2 strategies.

METHODS

A modified Susceptible, Exposed, Infectious, Recovered, and Deceased (SEIRD) model was employed to assess the situation in Israel, a small country with ∼9 million people. The incremental cost-effectiveness ratio (ICER) of these strategies as well as the expected number of infected individuals and deaths were calculated.

RESULTS

A nationwide lockdown is expected to save, on average, 274 (median 124, interquartile range: 71-221) lives compared to the "testing, tracing, and isolation" approach. However, the ICER will be, on average, $45 104 156 (median $49.6 million, interquartile range: 22.7-220.1) to prevent 1 case of death.

CONCLUSION

A national lockdown has a moderate advantage in saving lives with tremendous costs and possible overwhelming economic effects. These findings should assist decision makers dealing with additional waves of this pandemic.

A real-life setting evaluation of the effect of remdesivir on viral load in COVID-19 patients admitted to a large tertiary centre in Israel

OBJECTIVES

The effectiveness of remdesivir, a Food and Drug Administration-approved drug for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has been repeatedly questioned during the current coronavirus disease 2019 (COVID-19) pandemic. Most of the recently reported studies were randomized controlled multicentre clinical trials. Our goal was to test the efficiency of remdesivir in reducing nasopharyngeal viral load and hospitalization length in a real-life setting in patients admitted to a large tertiary centre in Israel.

METHODS

A total of 142 COVID-19 patients found to have at least three reported SARS-CoV-2 quantitative RT-PCR tests during hospitalization were selected for this study. Of these, 29 patients received remdesivir, while the remaining non-treated 113 patients served as controls.

RESULTS

Among the tested parameters, the control and remdesivir groups differed significantly only in the intubation rates. Remdesivir treatment did not significantly affect nasopharyngeal viral load, as determined by comparing the differences between the first and last cycle threshold values of the SARS-CoV-2 quantitative RT-PCR tests performed during hospitalization (cycle threshold 7.07 ± 6.85 vs. 7.08 ± 7.27, p 0.977 in the control and treated groups, respectively). Remdesivir treatment shortened hospitalization length by less than a day compared with non-treated controls and by 3.1 days when non-intubated patients from both groups were compared. These differences, however, were not statistically significant, possibly because of the small size of the remdesivir group.

DISCUSSION

Remdesivir was not associated with nasopharyngeal viral load changes, but our study had a significant disease severity baseline imbalance and was not powered to detect viral load or clinical differences.

Abnormal liver tests in patients with SARS-CoV-2 or influenza - prognostic similarities and temporal disparities

Background & Aims

Abnormal liver tests are common in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, but a possible direct role of the virus in liver injury and its association with short-term outcomes are controversial. Therefore, we aimed to compare the pattern of abnormal liver tests in patients with SARS-CoV-2 with those of patients infected with influenza, a non-hepatotropic respiratory virus, and their association with worse outcomes during hospitalisation.

Methods

We performed a retrospective cohort study of 1,737 hospitalised patients (865 with influenza and 872 with SARS-CoV-2) in a tertiary medical centre. We defined abnormal liver tests as alanine transaminase or aspartate transaminase ≥40 IU/ml at any time-point during hospitalisation.

Results

Abnormal liver tests were mild to moderate in most patients regardless of infection type, but the majority of patients with influenza had a transaminase peak earlier during hospitalisation compared with patients with SARS-CoV-2. Abnormal liver tests correlated with markers of severe disease in either influenza or SARS-CoV-2 infections, and were associated with death, occurring mainly in patients with severe liver test abnormalities (>200 IU/L) (38.7% and 60% of patients with influenza or SARS-CoV-2, respectively). In multivariate analysis, controlling for age, sex, lymphopaenia, and C-reactive protein, liver test abnormalities remained significantly associated with death for influenza (odds ratio 4.344; 95% CI 2.218-8.508) and SARS-CoV-2 (odds ratio 3.898; 95% CI 2.203-6.896). These results were confirmed upon propensity score matching.

Conclusions

Abnormal liver tests during hospitalisation with SARS-CoV-2 or influenza infections are common, may differ in their time course, and reflect disease severity. They are associated with worse outcomes, mainly in patients with severe liver test abnormalities, regardless of infection type.

Lay summary

Coronavirus disease 2019 (COVID-19) is a serious global health pandemic, the causative agent of which is severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Abnormal liver tests are common among SARS-CoV-2 infected patients and are often associated with worse outcomes. Herein, we compare the pattern of abnormal liver tests and their association with disease severity between 2 major non-hepatotropic respiratory viruses: SARS-CoV-2 and influenza. We show that abnormal liver tests are common in both infections, may slightly differ in their kinetics, and are associated with worse outcomes, especially in patients with severe liver test abnormalities. These results strongly suggest that abnormal liver tests in SARS-CoV-2 patients reflect disease severity, rather than a virus-mediated direct liver injury, and should be closely followed in admitted patients.

Response guided therapy for reducing duration of direct acting antivirals in chronic hepatitis C infected patients: a Pilot study

The advent of direct-acting antivirals (DAAs) has transformed the landscape of hepatitis C virus (HCV) management. We aimed to prospectively (real-time) evaluate the feasibility of using a response-guided therapy approach, based on mathematical modeling of early viral kinetics, to reduce the duration of DAAs therapy. Patients were treated with DAAs according to the physicians' preference. HCV was measured at baseline and at day 2 and weeks 1, 2 and 4 after treatment initiation. The primary endpoint was the proportion of patients with sustained-virological response (SVR) at 12 and/or 24 weeks post-treatment. Twenty-nine patients (mean age 54 ± 16, 44% females, 73% with HCV genotype 1), were enrolled and all completed therapy. Treatment duration was shortened in 11 of the 29 patients (38%). SVR was achieved in 28 of the 29 patients (97%). Relapse occurred post treatment in a single case of a non-cirrhotic male with genotype 3, who was treated with sofosbuvir/velpatasvir for 6 weeks. Virus sequencing did not identify baseline or treatment emergent resistance associated substitutions. Real-time mathematical modeling of early HCV kinetics can be utilized for shortening DAAs duration in approximately 40% of patients without compromising treatment efficacy.Clinical trial registration: ClinicalTrials.gov Identifier: NCT03603327.

High frequency of multiclass HCV resistance-associated mutations in patients failing direct-acting antivirals: real-life data

BACKGROUND

Direct-acting antiviral (DAA) therapy has dramatically increased sustained virological response rates in HCV-infected patients. However, resistance-associated substitutions (RAS) interfering with NS3- and NS5A-targeted therapy, still emerge. This real-life study analysed the type and frequency of RAS in rare cases of patients failing DAA regimens in 12 clinical centres in Israel.

METHODS

Blood samples and clinical data from 49 patients who failed various DAAs were collected. RAS identified in the NS3 and NS5A regions by population (Sanger) and next-generation sequencing (NGS) were compared by treatment regimen and HCV subtypes.

RESULTS

The majority (71.4%, 35/49) of patients were infected with the genotype (GT)1b strain, while 12.2% (6/49) carried GT1a and 14.3% GT3a/b (7), GT4a (1) and GT1b/GT3a. RAS were identified in 85.7% (42/49) of failures, of which 90.5% (38/42) were clinically relevant RAS (known to be associated with a specific GT and DAA in patients failing therapy or those with more than twofold change in in vitro replicon assays). The most abundant RAS were 168A/E/Q/G/N/V (32.6%, 16/49) identified in NS3, and 93H/N (61.2%, 30/49), 31I/M/V (34.7%, 17/49) and 30R/H/K (12.2%, 6/49), identified in NS5A. Significantly more clinically relevant RAS were identified in NS5A (82.2%, 37/45) than in NS3 (35.7%, 10/28; P<0.01). While RAS were identified in all GT1a, GT3b and GT4a failures (100%, 10/10), only 71.8% (28/39) of GT1b or GT3a failures had RAS (P=0.09). In four cases, NGS identified additional clinically relevant RAS and in one patient, NGS deciphered coexistence of GT3a and GT1b infections.

CONCLUSIONS

Our findings, together with additional real-life data, will contribute to the optimization of retreatment in DAA failure, when cost-related and suboptimal regimens must be employed.

Association Between Fibrosis Stage and Outcomes of Patients With Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis

BACKGROUND & AIMS

Biopsy-confirmed liver fibrosis is a prognostic factor for patients with nonalcoholic fatty liver disease (NAFLD). We performed a systematic review to quantify the prognostic value of fibrosis stage in patients with NAFLD and the subgroup of patients with nonalcoholic steatohepatitis (NASH) and to assess the evidence that change in fibrosis stage is a surrogate endpoint.

METHODS

We searched the MEDLINE, Embase, Cochrane Library, and trial registry databases through August 2018 for prospective or retrospective cohort studies of liver-related clinical events and outcomes in adults with NAFLD or NASH. We collected data on mortality (all cause and liver related) and morbidity (cirrhosis, liver cancer, and all liver-related events) by stage of fibrosis, determined by biopsy, for patients with NAFLD or NASH. Using fibrosis stage 0 as a reference population, we calculated fibrosis stage-specific relative risk (RR) and 95% confidence interval (CI) values for mortality and morbidities. We performed fixed-effect and random-effect model meta-analyses. Metaregression was used to examine associations among study design (prospective vs retrospective cohort), overall risk of bias (medium or high), and mean duration of follow-up (in years).

RESULTS

Our meta-analysis included 13 studies, comprising 4428 patients with NAFLD; 2875 of these were reported to have NASH. Compared with no fibrosis (stage 0), unadjusted risk increased with increasing stage of fibrosis (stage 0 vs 4): all-cause mortality RR, 3.42 (95% CI, 2.63-4.46); liver-related mortality RR, 11.13 (95% CI, 4.15-29.84); liver transplant RR, 5.42 (95% CI, 1.05-27.89); and liver-related events RR, 12.78 (95% CI, 6.85-23.85). The magnitude of RR did not differ significantly after adjustment for confounders, including age or sex in the subgroup of NAFLD patients with NASH. Three studies examined the effects of increasing fibrosis on quality of life had inconsistent findings.

CONCLUSIONS

In a systematic review and meta-analysis, we found biopsy-confirmed fibrosis to be associated with risk of mortality and liver-related morbidity in patients with NAFLD, with and without adjustment for confounding factors and in patients with reported NASH. Further studies are needed to assess the association between fibrosis stage and patient quality of life and establish that change in liver fibrosis stage is a valid endpoint for use in clinical trials.

Liver steatosis is a major predictor of poor outcomes in chronic hepatitis C patients with sustained virological response

Sustained virological response (SVR) results in reduced incidence of hepatocellular carcinoma (HCC) and mortality among chronic hepatitis C (CHC) patients with advanced fibrosis. Since both advanced fibrosis and liver steatosis (LS) may coexist in CHC patients, we evaluated their individual effects on a composite outcome of all-cause mortality and HCC in CHC patients with SVR following direct-acting antivirals (DAA) treatment. We retrospectively evaluated inception cohort of 515 CHC patients who achieved SVR following treatment with DAA, with a mean follow-up of 24 months. Baseline liver fibrosis was assessed by transient elastography, and LS was validated by at least three independent ultrasonographic examinations. 211 of 515 patients (41%) had baseline LS. Patients with LS had a higher cumulative rate of all-cause mortality and HCC at 2 years of follow-up compared to patients without LS (15.75% and 2.79%, respectively, P < 0.001), although they did not have increased incidence of advanced fibrosis or cirrhosis. Consistently, multivariate analysis showed that LS was associated with a significant 7.5-fold increased risk of all-cause mortality and HCC (HR 7.51, 95% C.I 3.61-13.36, P < 0.001) even upon adjustment to components of the metabolic syndrome, whereas advanced fibrosis showed only a trend towards statistical significance (HR 2.32, 95% C.I 0.97-6.59, P = 0.06). In conclusion, LS is a major predictor of all-cause mortality and HCC in patients who achieved SVR following DAA treatment regardless of fibrosis stage. These patients should be rigorously screened for HCC.

Cabozantinib for patients with advanced hepatocellular carcinoma: a cost-effectiveness analysis

BACKGROUND AND AIMS

The multi-kinase inhibitor sorafenib is a first-line drug for patients with advanced hepatocellular carcinoma (HCC). Treatment options for patients whose disease has progressed on sorafenib are limited. In a recent randomized controlled trial (CELESTIAL trial), patients with advanced HCC who had failed prior systemic therapy had moderate progression-free survival and overall survival advantages when treated with the multi-kinase inhibitor cabozantinib. However, since this treatment is costly and is accompanied by significant adverse events in a large proportion of patients, its cost-effectiveness in these patients should be determined.

METHODS

We developed a Markov model incorporating health outcomes, measured by life-years and quality-adjusted life-years (QALYs) to evaluate the cost-effectiveness of cabozantinib compared with placebo in patients who have failed prior systemic therapy.

RESULTS

Treatment with cabozantinib results in a mean gain of 11.6 weeks of life (0.22 life-years) as compared with placebo. When quality of life was incorporated, treatment with cabozantinib produced a gain of 0.16 QALYs. The total mean incremental cost of cabozantinib was US$76,406 per patient. The incremental cost-effectiveness ratio for cabozantinib compared with best supportive care was US$469,374/QALY using the recommended dose of 60 mg cabozantinib daily.

CONCLUSION

Our results suggest that the use of cabozantinib in patients with advanced HCC who have progressed on prior treatment, results in a modest incremental benefit with high incremental costs, suggesting that it is not cost-effective at conventional willingness to pay thresholds.

Liver steatosis is a strong predictor of mortality and cancer in chronic hepatitis B regardless of viral load

Liver steatosis may occur concomitantly in patients with chronic hepatitis B infection (CHB) and is implicated in increased morbidity and mortality. Hepatitis B virus (HBV) viral load is a marker for disease progression and long-term outcomes in CHB. We investigated the association between liver steatosis and HBV viral load and their individual effects on all-cause mortality and the development of cancer in patients with CHB and liver steatosis.

Methods

This retrospective study included 524 treatment-naïve patients with CHB, with a mean follow-up of 6 years. Liver biopsy was available for 170 patients and liver steatosis was validated by at least 3 ultrasonographic examinations.

Results

A total of 241/524 (46%) patients with CHB had liver steatosis, with a strong correlation between the degree of liver steatosis as assessed by ultrasonography or by liver biopsy (r = 0.9, p < 0.001). Although liver steatosis was not significantly associated with advanced fibrosis, a multivariate analysis showed that liver steatosis was associated with a 4-fold increased risk of all-cause mortality and cancer (hazard ratio 4.35; 95% CI 1.69–8.99; p < 0.001), irrespective of other major metabolic factors. However, baseline HBV viral load was not significantly associated with this composite outcome (hazard ratio 1.65; p = 0.29). In addition, liver steatosis was inversely associated with HBV viral load.

Conclusion

Patients with CHB and liver steatosis have an increased risk of all-cause mortality and cancer development compared to patients with CHB without liver steatosis, regardless of their baseline HBV viral load. Although tending to have a lower baseline viral load, patients with CHB and liver steatosis should be closely monitored irrespective of viral load.

Lay summary

Patients with chronic hepatitis B infection (CHB) may have liver steatosis at the same time. Here we show that in patients with CHB, liver steatosis is significantly associated with all-cause mortality and cancer, irrespective of other major metabolic factors, and the effect of liver steatosis on mortality and cancer is stronger than the effect of hepatitis B viral load on these outcomes. Thus, patients with CHB and liver steatosis should be closely monitored, irrespective of their viral load.

•

HBV viral load is an important predictor of adverse outcomes in patients with chronic HBV (CHB).

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Liver steatosis may co-occur with CHB but its effect on all-cause mortality and cancer has not been determined.

•

Liver steatosis is significantly associated with all-cause mortality and cancer in patients with CHB.

•

The effect of liver steatosis on mortality and cancer is stronger than the effect of HBV viral load.

•

Patients with CHB and liver steatosis should be closely monitored, irrespective of their viral load.

Transplantation of Livers from Old Donors: Pushing the Envelope Beyond the Seventh Decade

BACKGROUND

The lack of organs for liver transplantation has prompted transplant professionals to study potential solutions, such as the use of livers from donors older than 70 years. This strategy is not widely accepted because potential risks of vascular and biliary complications and recurrence of hepatitis C.

OBJECTIVES

To examine the efficacy and safety of liver grafts from older donors for transplantation.

METHODS

A retrospective analysis of data on 310 adults who underwent deceased donor liver transplantation between 2005 and 2015 was conducted. We compared graft and recipient survival, as well as major complications, of transplants performed with grafts from donors younger than 70 years (n=265, control group) and those older than 70 years (n=45, older-donor group), followed by multivariate analysis, to identify risk factors.

RESULTS

There was no significant difference between the control and older-donor group at 1, 5, and 10 years of recipient survival (79.5% vs. 73.3%, 68.3% vs. 73.3%, 59.2% vs. 66.7%, respectively) or graft survival (74.0% vs. 71.0%, 62.7% vs. 71.0%, 54.8% vs. 64.5%, respectively). The rate of biliary and vascular complications was similar in both groups. Significant risk factors for graft failure were hepatitis C (hazard ratio [HR] = 1.92, 95% confidence interval [95%CI] 1.16-2.63), older donor age (HR = 1.02, 95%CI 1.007-1.031), and male gender of the recipient (HR = 1.65, 95%CI 1.06-2.55).

CONCLUSIONS

Donor age affects liver graft survival. However, grafts from donors older than 70 years may be equally safe if cold ischemia is maintained for less than 8 hours.

Regorafenib treatment for patients with hepatocellular carcinoma who progressed on sorafenib-A cost-effectiveness analysis

BACKGROUND AND AIMS

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer related deaths. Patients with advanced HCC are treated with sorafenib. A recent randomized controlled trial demonstrated a survival benefit for regorafenib treatment in patients with advanced HCC who had progressed on sorafenib. We aimed to evaluate the cost-effectiveness of this approach.

METHODS

To evaluate the cost effectiveness of regorafenib, we used a Markov model that incorporates health outcomes, measured by life-years and quality-adjusted life-years (QALYs). Drug costs were based on 2017 discounted prices. Model robustness was validated by probabilistic sensitivity analyses using Monte Carlo simulations.

RESULTS

The use of regorafenib results in a gain of 19.76 weeks of life (0.38 Life Years) as compared to placebo. When adjusted for quality of life, using regorafenib produced a gain of 0.25 quality adjusted life years (QALYs). The incremental cost-effectiveness ratio for regorafenib compared with best supportive care was between $201,797 and $268,506 per QALY.

CONCLUSION

The modest incremental benefit at a relatively high incremental cost of regorafenib treatment suggests that it is not cost-effective at commonly accepted willingness to pay thresholds.

Noninvasive scoring systems predict hepatic and extra-hepatic cancers in patients with nonalcoholic fatty liver disease

BACKGROUND

Liver fibrosis predicts liver-related morbidity and mortality in patients with non-alcoholic fatty liver disease (NAFLD). Non-invasive scores correlate with the degree of liver fibrosis in these patients.

AIMS AND METHODS

To investigate the accuracy of noninvasive scoring systems in predicting long-term outcomes and cancer incidence of patients with NAFLD, we performed a single-center retrospective study of patients with biopsy proven NAFLD. Mean follow up period was 100 months. Outcomes included liver-related complications, hospitalizations, overall mortality and the development of any malignancies.

RESULTS

32 patients had advanced fibrosis (F3-F4) per biopsy at baseline and 121 patients had mild to moderate fibrosis (F0-F2). Both advanced histologic fibrosis stage as well as higher non-invasive scores predicted repeated hospitalizations and longer hospitalization stays. In a multivariate analysis, liver fibrosis (p = 0.002), FIB-4 score (p<0.001), NFS (p<0.001) but not APRI score (p = 0.07) were predictors of overall mortality, and the occurrence of malignancies was associated with higher APRI (p<0.001), FIB-4 (p<0.001) and NFS (p = 0.008) scores, but not with advanced fibrosis, as determined by liver biopsy (p = 0.105).

CONCLUSIONS

In NAFLD patients, noninvasive scoring systems are good predictors of morbidity and mortality and may have an additive value in predicting the development of hepatic and extra-hepatic cancers.

The Pattern of Elevated Liver Function Tests in Nonalcoholic Fatty Liver Disease Predicts Fibrosis Stage and Metabolic-Associated Comorbidities

BACKGROUND

Patients with nonalcoholic fatty liver disease (NAFLD) and with abnormal liver function tests (LFTs) most commonly present with elevated hepatocellular enzymes (H pattern), but a subset of patients is found to have elevated cholestatic enzymes (C pattern) or a mixed (M) pattern.

AIMS AND METHODS

To determine whether the epidemiologic background and comorbidities, as well as the degree of liver fibrosis, differ between NAFLD patients with different patterns of elevated LFTs by retrospectively analyzing data of 106 patients with a biopsy-proven diagnosis of NAFLD. The pattern of elevated LFTs was determined by adopting the "R-Ratio" formula commonly used for drug-induced liver injury.

RESULTS

Advanced fibrosis (F > 2) was found in 15 out of 48 (31.3%) patients with a C pattern of elevated LFTs as compared to 2 out of 44 (4.5%) in M patients and 2 out of 11 (18.2%) in H patients (p = 0.004). Group C patients are older and also had a higher prevalence of diabetes, a higher mean hemoglobin A1c, and a higher prevalence of hypertension, as well as a trend for a higher prevalence of hypertriglyceridemia.

CONCLUSIONS

Using a simple formula incorporating routine LFTs can help to categorize NAFLD patients as low or high risk for advanced fibrosis stage and metabolic-associated comorbidities.

The antiviral protein Viperin suppresses T7 promoter dependent RNA synthesis-possible implications for its antiviral activity

Viperin is a multifunctional interferon-inducible broad-spectrum antiviral protein. Viperin belongs to the S-Adenosylmethionine (SAM) superfamily of enzymes known to catalyze a wide variety of radical-mediated reactions. However, the exact mechanism by which viperin exerts its functions is still unclear. Interestingly, for many RNA viruses viperin was shown to inhibit viral RNA accumulation by interacting with different viral non-structural proteins. Here, we show that viperin inhibits RNA synthesis by bacteriophage T7 polymerase in mammalian cells. This inhibition is specific and occurs at the RNA level. Viperin expression significantly reduced T7-mediated cytoplasmic RNA levels. The data showing that viperin inhibits the bacteriophage T7 polymerase supports the conservation of viperin’s antiviral activity between species. These results highlight the possibility that viperin might utilize a broader mechanism of inhibition. Accordingly, our results suggest a novel mechanism involving polymerase inhibition and provides a tractable system for future mechanistic studies of viperin.

Inhibition of pMAPK14 Overcomes Resistance to Sorafenib in Hepatoma Cells with Hepatitis B Virus

Hepatitis B virus (HBV) targets the liver and is a major driver for liver cancer. Clinical data suggest that HBV infection is associated with reduced response to treatment with the multi-kinase inhibitor sorafenib, the first available molecularly targeted anti-hepatocellular carcinoma (HCC) drug. Given that Raf is one of the major targets of sorafenib, we investigated the activation state of the Raf-Mek-Erk pathway in the presence of HBV and in response to sorafenib. Here we show that hepatoma cells with replicating HBV are less susceptible to sorafenib inhibitory effect as compared to cells in which HBV expression is suppressed. However, although HBV replication is associated with increased level of pErk, its blockade only modestly augments sorafenib effect. In contrast, the phosphorylated form of the pro-oncogenic Mitogen-Activated Protein Kinase 14 (pMAPK14), a protein kinase that was recently linked to sorafenib resistance, is induced in sorafenib-treated hepatoma cells in association with HBV X protein expression. Knocking down pMAPK14 results in augmentation of the therapeutic efficacy of sorafenib and largely alleviates resistance to sorafenib in the presence of HBV. Thus, this study suggests that HBV promotes HCC resistance to sorafenib. Combining pMAPK14 inhibitors with sorafenib may be beneficial in patients with HBV-associated HCC.

Characterization of hepatitis B and delta coinfection in Israel

BACKGROUND

Characteristics of hepatitis B (HBV) and delta (HDV) coinfection in various geographical regions, including Israel, remain unclear. Here we studied HDV seroprevalence in Israel, assessed HDV/HBV viral loads, circulating genotypes and hepatitis delta antigen (HDAg) conservation.

METHODS

Serological anti HDV IgG results from 8969 HBsAg positive individuals tested in 2010-2015 were retrospectively analyzed to determine HDV seroprevalence. In a cohort of HBV/HDV coinfected (n=58) and HBV monoinfected (n=27) patients, quantitative real-time PCR (qRT-PCR) and sequencing were performed to determine viral loads, genotypes and hepatitis delta antigen (HDAg) protein sequence.

RESULTS

6.5% (587/8969) of the HBsAg positive patients were positive for anti HDV antibodies. HDV viral load was >2 log copies/ml higher than HBV viral load in most of the coinfected patients with detectable HDV RNA (86%, 50/58). HDV genotype 1 was identified in all patients, most of whom did not express HBV. While 66.6% (4/6) of the HBV/HDV co-expressing patients carried HBV-D2 only 18.5% (5/27) of the HBV monoinfections had HBV-D2 (p=0.03). Higher genetic variability in the HDAg protein sequence was associated with higher HDV viral load.

CONCLUSIONS

The overall significant prevalence of HDV (6.5%) mandates HDV RNA testing for all coinfected patients. Patients positive for HDV RNA (characterized by low HBV DNA blood levels) carried HDV genotype 1. Taken together, the significant HDV seroprevalence and the lack of effective anti-HDV therapy, necessitates strict clinical surveillance especially in patients with higher HDV viral loads and increased viral evolution.

A robust cell culture system supporting the complete life cycle of hepatitis B virus

The discovery of sodium taurocholate cotransporting polypeptide (NTCP) as the hepatitis B virus (HBV) receptor enabled researchers to create hepatoma cell lines susceptible to HBV infection. Infection in current systems, however, is inefficient and virus fails to spread. Infection efficiency is enhanced by treating cells with polyethylene glycol 8000 (PEG) during infection. However, this alone does not promote virus spread. Here we show that maintaining PEG in culture medium increases the rate of infection by at least one order of magnitude, and, most importantly, promotes virus spread. To demonstrate the utility of this system, we show that two interferon-stimulated genes (ISGs), ISG20 and tetherin, restrict HBV spread in NTCP-expressing hepatoma cells. Thus, this protocol can be easily applied to existing cell culture systems to study the complete HBV life cycle, including virus spread.

AST to Platelet Ratio Index and fibrosis 4 calculator scores for non-invasive assessment of hepatic fibrosis in patients with non-alcoholic fatty liver disease

BACKGROUND & AIMS

Liver fibrosis is the single most important prognostic factor in patients with non-alcoholic fatty liver disease (NAFLD). The predictive value of the AST to Platelet Ratio Index (APRI) score, originally developed for fibrosis assessment in hepatitis C virus (HCV) patients, is much less known in the context of NAFLD patients.

METHODS

We retrospectively compared the performance of APRI and fibrosis 4 calculator (FIB-4) scores in NAFLD patients with documented liver biopsies, to their performance in chronic HCV patients.

RESULTS

153 patients with biopsy-proven NAFLD and 297 patients with biopsy-proven chronic HCV infection were included. The APRI score was a good predictor for advanced fibrosis in NAFLD patients (area under the ROC curve 0.8307) although it was modestly inferior as compared to the well-validated FIB-4 score (area under the ROC curve 0.8959). The predictive value of APRI score in NALFD patients was inferior as compared to its predictive value in HCV patients (area under the ROC curve of 0.8307 versus 0.9965). In contrast to FIB-4, APRI score was not a good discriminator between intermediate stages of fibrosis in NAFLD patients.

CONCLUSIONS

APRI and Fib-4 scores are reasonable tools to allocate NAFLD patients with advanced fibrosis. FIB-4 may better discriminate between intermediate fibrosis stages.

Patients' Age Rather Than Model of End-Stage Liver Disease Score Predicts Survival After Liver Transplantation

BACKGROUND

The model of end-stage liver disease (MELD) score is the standard tool for prioritizing patients awaiting liver transplantation. There is currently no definite high cutoff score reflecting disease severity that might exclude patients from transplantation. Furthermore, the age limit that used to disqualify patients from eligibility to transplantation was recently withdrawn in several countries.

AIMS

The aims of this study were to assess the effects of MELD score and age at time of transplantation on patients' short- and long-term survival.

METHODS

We conducted a retrospective single-center study on a cohort of patients transplanted for the first time due to non-fulminant liver failure.

RESULTS

Four hundred and seventeen patients (mean age 50.2 years, 63% males) who underwent liver transplantation for the first time were included. Both higher patients' and donors' age were significantly associated with increased long-term mortality (p = 0.007, 95% CI 1.006-1.038 for patient age, p = 0.02, 95% CI 1.002-1.023 for donor age). Patients' age remained significantly associated with survival at 1 year post-transplantation, as well. We found no association between higher MELD score at transplantation and long-term mortality (p = 0.189, 95% CI 0.99-1.051) irrespective of patients' age. Specifically, when patients were divided according to their MELD score at transplantation (MELD < 15, MELD 15-25 and MELD > 25), no significant differences in long-term survival were detected between these three subgroups. Results did not differ significantly in a subgroup analysis of patients without hepatocellular carcinoma at the time of transplantation.

CONCLUSIONS

Patients' and donors' age rather than patients' MELD score at transplantation determine survival following liver transplantation.

HCV genotype-1 subtypes and resistance-associated substitutions in drug-naive and in direct-acting antiviral treatment failure patients

BACKGROUND

Direct-acting antiviral (DAA) treatment regimens and response rates of patients with HCV genotype-1 (GT1) are currently considered subtype-dependent. Identification of clinically relevant resistance-associated substitutions (RASs) in the NS3 and NS5A proteins at baseline and in DAA failures, may also impact clinical decisions.

METHODS

In a multicentre cohort study (n=308), NS3 or NS5B sequencing (n=248) was used to discriminate between GT1 subtypes. The correlation between baseline NS3 and NS5A RASs on the 12-week sustained virological response (SVR12) rates of 160 of the patients treated with second-generation DAAs was also assessed. Post-treatment resistance analysis was performed on samples from 58 patients exhibiting DAA virological failure.

RESULTS

GT1a, GT1b and GT1d subtypes were identified in 23.0%, 75.4% and 1.2% of tested samples. GT1b was most prevalent (97.7%, 128/131) among patients born in the former Soviet Union. The Q80K NS3 RAS was identified in 17.5% (10/57) of the GT1a carriers, most of whom were Israeli-born. NS3 and NS5A baseline RASs showed a negligible correlation with SVR12 rates. Treatment-emergent RASs were observed among 8.9% (4/45) and 76.9% (10/13) of first- and second-generation DAA failures, respectively, with D168V/E (NS3), Y93H and L31M (NS5A) being the most prevalent mutations.

CONCLUSIONS

NS3 sequencing analysis can successfully discriminate between GT1 subtypes and identify NS3 amino acid substitutions. While pre-treatment NS3 and NS5A RASs marginally affect second-generation DAA SVR12 rates, post-treatment resistance analysis should be considered prior to re-therapy.

A Broad RNA Virus Survey Reveals Both miRNA Dependence and Functional Sequestration

Small non-coding RNAs have emerged as key modulators of viral infection. However, with the exception of hepatitis C virus, which requires the liver-specific microRNA (miRNA)-122, the interactions of RNA viruses with host miRNAs remain poorly characterized. Here, we used crosslinking immunoprecipitation (CLIP) of the Argonaute (AGO) proteins to characterize strengths and specificities of miRNA interactions in the context of 15 different RNA virus infections, including several clinically relevant pathogens. Notably, replication of pestiviruses, a major threat to milk and meat industries, critically depended on the interaction of cellular miR-17 and let-7 with the viral 3' UTR. Unlike canonical miRNA interactions, miR-17 and let-7 binding enhanced pestivirus translation and RNA stability. miR-17 sequestration by pestiviruses conferred reduced AGO binding and functional de-repression of cellular miR-17 targets, thereby altering the host transcriptome. These findings generalize the concept of RNA virus dependence on cellular miRNAs and connect virus-induced miRNA sequestration to host transcriptome regulation.

Humanized mice efficiently engrafted with fetal hepatoblasts and syngeneic immune cells develop human monocytes and NK cells

BACKGROUND & AIMS

Human liver chimeric mice are useful models of human hepatitis virus infection, including hepatitis B and C virus infections. Independently, immunodeficient mice reconstituted with CD34(+) hematopoietic stem cells (HSC) derived from fetal liver reliably develop human T and B lymphocytes. Combining these systems has long been hampered by inefficient liver reconstitution of human fetal hepatoblasts. Our study aimed to enhance hepatoblast engraftment in order to create a mouse model with syngeneic human liver and immune cells.

METHODS

The effects of human oncostatin-M administration on fetal hepatoblast engraftment into immunodeficient fah(-/-) mice was tested. Mice were then transplanted with syngeneic human hepatoblasts and HSC after which human leukocyte chimerism and functionality were analyzed by flow cytometry, and mice were challenged with HBV.

RESULTS

Addition of human oncostatin-M enhanced human hepatoblast engraftment in immunodeficient fah(-/-) mice by 5-100 fold. In contrast to mice singly engrafted with HSC, which predominantly developed human T and B lymphocytes, mice co-transplanted with syngeneic hepatoblasts also contained physiological levels of human monocytes and natural killer cells. Upon infection with HBV, these mice displayed rapid and sustained viremia.

CONCLUSIONS

Our study provides a new mouse model with improved human fetal hepatoblast engraftment and an expanded human immune cell repertoire. With further improvements, this model may become useful for studying human immunity against viral hepatitis.

LAY SUMMARY

Important human pathogens such as hepatitis B virus, hepatitis C virus and human immunodeficiency virus only infect human cells which complicates the development of mouse models for the study of these pathogens. One way to make mice permissive for human pathogens is the transplantation of human cells into immune-compromised mice. For instance, the transplantation of human liver cells will allow the infection of these so-called "liver chimeric mice" with hepatitis B virus and hepatitis C virus. The co-transplantation of human immune cells into liver chimeric mice will further allow the study of human immune responses to hepatitis B virus or hepatitis C virus. However, for immunological studies it will be crucial that the transplanted human liver and immune cells are derived from the same human donor. In our study we describe the efficient engraftment of human fetal liver cells and immune cells derived from the same donor into mice. We show that liver co-engraftment resulted in an expanded human immune cell repertoire, including monocytes and natural killer cells in the liver. We further demonstrate that these mice could be infected with hepatitis B virus, which lead to an expansion of natural killer cells. In conclusion we have developed a new mouse model that could be useful to study human immune responses to human liver pathogens.

Hepatitis C virus cures after direct acting antiviral-related drug-induced liver injury: Case report

The United States Food and Drug Administration recently warned that the direct acting antiviral (DAA) combination hepatitis C virus (HCV) treatment of Paritaprevir, Ombitasvir, Dasabuvir, Ritonavir, and Ribavirin (PODr + R) can cause severe liver injury in patients with advanced liver disease. Drug induced liver injury was observed in a small number of patients with decompensated cirrhosis treated with other DAAs, but has not been reported in patients with compensated cirrhosis. We report a case of a 74-year-old woman with chronic HCV and Child-Pugh class A cirrhosis (compensated cirrhosis) treated with PODr + R. The patient presented on day 14 of PODr + R therapy with jaundice and new-onset ascites. Her total bilirubin level increased to 23 mg/dL and international normalized ratio rose to 1.65, while aminotransferase levels remained relatively stable. Hepatitis C treatment was discontinued on day 24 and she gradually recovered. Follow-up testing showed that she achieved a sustained virologic response. In conclusion, hepatic decompensation developed within two weeks of starting treatment with PODr + R in a patient with Child-Pugh class A cirrhosis and was characterized by jaundice and ascites with stable aminotransferase levels. Careful monitoring is warranted in patients with HCV-related cirrhosis treated with PODr + R.

New therapies for chronic hepatitis B

Approximately 350 million people worldwide are chronically infected with hepatitis B virus (HBV), representing a significant public health challenge. Nucleos/tide analogues (NUCs) and interferon alpha (IFNα), the current standard of care for chronic infection, aim at preventing progression of the disease to cirrhosis, hepatocellular carcinoma (HCC) and death. However, in contrast to the case of hepatitis C virus infection, in which novel antiviral drugs cure the vast majority of treated patients, in regard to HBV, cure is rare due to the unusual persistence of viral DNA in the form of covalently closed circular DNA (cccDNA) within the nucleus of infected cells. Available therapies for HBV require lifelong treatment and surveillance, as reactivation frequently occurs following medication cessation and the occurrence of HCC is decreased but not eliminated, even after years of successful viral suppression. Progress has been made in the development of new therapeutics, and it is likely that only a combination of immune modulators, inhibitors of gene expression and replication and cccDNA-targeting drugs will eradicate chronic infection. This review aims to summarize the state of the art in HBV drug research highlighting those agents with the greatest potential for success based on in vitro as well as on data from clinical studies.

Advances and Challenges in Studying Hepatitis B Virus In Vitro

Hepatitis B virus (HBV) is a small DNA virus that infects the liver. Current anti-HBV drugs efficiently suppress viral replication but do not eradicate the virus due to the persistence of its episomal DNA. Efforts to develop reliable in vitro systems to model HBV infection, an imperative tool for studying HBV biology and its interactions with the host, have been hampered by major limitations at the level of the virus, the host and infection readouts. This review summarizes major milestones in the development of in vitro systems to study HBV. Recent advances in our understanding of HBV biology, such as the discovery of the bile-acid pump sodium-taurocholate cotransporting polypeptide (NTCP) as a receptor for HBV, enabled the establishment of NTCP expressing hepatoma cell lines permissive for HBV infection. Furthermore, advanced tissue engineering techniques facilitate now the establishment of HBV infection systems based on primary human hepatocytes that maintain their phenotype and permissiveness for infection over time. The ability to differentiate inducible pluripotent stem cells into hepatocyte-like cells opens the door for studying HBV in a more isogenic background, as well. Thus, the recent advances in in vitro models for HBV infection holds promise for a better understanding of virus-host interactions and for future development of more definitive anti-viral drugs.

Micropatterned coculture of primary human hepatocytes and supportive cells for the study of hepatotropic pathogens

The development of therapies and vaccines for human hepatropic pathogens requires robust model systems that enable the study of host-pathogen interactions. However, in vitro liver models of infection typically use either hepatoma cell lines that exhibit aberrant physiology or primary human hepatocytes in culture conditions in which they rapidly lose their hepatic phenotype. To achieve stable and robust in vitro primary human hepatocyte models, we developed micropatterned cocultures (MPCCs), which consist of primary human hepatocytes organized into 2D islands that are surrounded by supportive fibroblast cells. By using this system, which can be established over a period of days, and maintained over multiple weeks, we demonstrate how to recapitulate in vitro hepatic life cycles for the hepatitis B and C viruses and the Plasmodium pathogens P. falciparum and P. vivax. The MPCC platform can be used to uncover aspects of host-pathogen interactions, and it has the potential to be used for drug and vaccine development.

Hepatitis B virus induces RNR-R2 expression via DNA damage response activation

BACKGROUND & AIMS

Hepatitis B virus (HBV) infects and replicates in quiescent hepatocytes, which are deficient in dNTPs, the critical precursors of HBV replication. Most tumor viruses promote dNTP production in host cells by inducing cell proliferation. Although HBV is known as a major cause of hepatocellular carcinoma, it does not lead to cellular proliferation. Instead, HBV acquires dNTPs by activating the expression of the R2 subunit of the Ribonucleotide Reductase (RNR) holoenzyme, the cell cycle gene that is rate-limiting for generation of dNTPs, without inducing the cell cycle. We wished to elucidate the molecular basis of HBV-dependent R2 expression in quiescent cells.

METHODS

Quiescent HepG2 cells were transduced with an HBV-containing lentiviral vector, and primary human hepatocytes were infected with HBV. DNA damage response and RNR-R2 gene expression were monitored under this condition.

RESULTS

We report here that HBV-induced R2 expression is mediated by the E2F1 transcription factor, and that HBV induces E2F1 accumulation, modification and binding to the R2 promoter. We found that Chk1, a known E2F1 kinase that functions in response to DNA damage, was activated by HBV. In cells where Chk1 was pharmacologically inhibited, or depleted by shRNA-mediated knockdown, HBV-mediated R2 expression was severely attenuated. Furthermore, we found that HBV attenuates DNA repair, thus reducing cellular dNTP consumption.

CONCLUSIONS

Our findings demonstrate that HBV exploits the Chk1-E2F1 axis of the DNA damage response pathway to induce R2 expression in a cell cycle-independent manner. This suggests that inhibition of this pathway may have a therapeutic value for HBV carriers.

CRISPR/Cas9 cleavage of viral DNA efficiently suppresses hepatitis B virus

Chronic hepatitis B virus (HBV) infection is prevalent, deadly, and seldom cured due to the persistence of viral episomal DNA (cccDNA) in infected cells. Newly developed genome engineering tools may offer the ability to directly cleave viral DNA, thereby promoting viral clearance. Here, we show that the CRISPR/Cas9 system can specifically target and cleave conserved regions in the HBV genome, resulting in robust suppression of viral gene expression and replication. Upon sustained expression of Cas9 and appropriately chosen guide RNAs, we demonstrate cleavage of cccDNA by Cas9 and a dramatic reduction in both cccDNA and other parameters of viral gene expression and replication. Thus, we show that directly targeting viral episomal DNA is a novel therapeutic approach to control the virus and possibly cure patients.

Virus associated malignancies: the role of viral hepatitis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third leading fatal cancer worldwide and its incidence continues to increase. Chronic viral hepatitis involving either hepatitis B virus (HBV) or hepatitis C virus (HCV) infection is the leading etiology for HCC, making HCC prevention a major goal of antiviral therapy. While recent clinical observations and translational research have enhanced our understanding of the molecular mechanisms driving the initiation and progression of HCC, much remains unknown. Current data indicates that HCC tumors are highly complex and heterogeneous resulting from the aberrant function of multiple molecular pathways. This complex biology is responsible, at least in part, for the absence of highly efficient target-directed therapies for this deadly cancer. Additionally, the direct or indirect effect of HBV and HCV infection on the development of HCC is still a contentious issue. Thus, the question remains whether viral hepatitis-associated HCC stems from virus-specific factors, and/or from a general mechanism involving inflammation and tissue regeneration. In this review we summarize general mechanisms implicated in HCC, emphasizing data generated by new technologies available today. We also highlight specific pathways by which HBV and HCV could be involved in HCC pathogenesis. However, improvements to current in vitro and in vivo systems for both viruses will be needed to rigorously define the temporal sequence and specific pathway dysregulations that drive the strong clinical link between chronic hepatitis virus infection and HCC.

Role of glucose-dependent insulinotropic polypeptide in adipose tissue inflammation of dipeptidylpeptidase 4-deficient rats

OBJECTIVES

Dipeptidyl peptidase 4 (DPP4) inhibitors, used in obese diabetic patients, reduce inflammation in several models. The role of chronic DPP4-deficiency (DPP4-) in diet-induced obesity with respect to insulin sensitivity and adipose tissue inflammation was investigated.

DESIGN AND METHODS

Insulin resistance was induced by 2 months high fat diet (HFD). In vitro effects of glucose-dependent insulinotropic polypeptide (GIP) were assessed in adipose tissue explants and stromal vascular fraction (SVF).

RESULTS

HFD-fed DPP4-rats gained significantly more weight and visceral fat mass, yet were more insulin sensitive. Adipose tissue of DPP4- rats demonstrated increased adipocyte maturation and increased expression of enzymes involved in triglyceride uptake and synthesis, yet increased adiponectin mRNA, reduced mRNA of proinflammatory cytokines and reduced vascular adhesion molecules, suggesting reduced inflammation. In vitro and in vivo experiments explored the role of GIP in inducing this phenotype. Indeed, we demonstrated that GIP directly enhanced adiponectin expression in rat and human adipose tissue explants and in SVF. Lastly, GIP administration to normal or HFD-fed rats elevated serum adiponectin and improved their glucose tolerance test.

CONCLUSION

In a HFD model, DPP4-rats exhibited reduced adipose tissue inflammation and improved insulin resistance, which may be mediated in part by GIP induction of adiponectin.

Serum bile acid levels as a predictor for the severity of liver fibrosis in patients with chronic hepatitis C

Serum bile acids (SBAs) are commonly elevated in cholestatic liver diseases, but it is unclear if SBA levels are also elevated in noncholestatic chronic liver diseases and whether those levels correlate with disease severity. We analysed SBA levels of 135 consecutive patients with chronic hepatitis C virus infection and correlated these levels with the degree of liver fibrosis as determined by liver biopsy. In addition, we assessed the accuracy of SBA levels as a noninvasive predictor for liver fibrosis by its comparison to the patients' FibroTest scores. Two-thirds (90/135 patients, 67%) of the study patients had nonsevere liver fibrosis (Metavir F0-F2), and the others (45/135, 33%) had severe fibrosis or cirrhosis (Metavir F3-F4). The SBA levels were significantly higher in patients with severe fibrosis as compared to nonsevere fibrosis (11.46 ± 10.01 vs 6.37 ± 4.69, P < 0.0001). Furthermore, a receiver operator characteristics curve based on a model that included serum bile acids, age, body mass index, serum AST, glucose and cholesterol levels suggested that this combination reliably predicts the degree of liver fibrosis and is not inferior to the current noninvasive FibroTest score (areas under the curve of 0.837 vs 0.83, respectively, P = 0.87). We conclude that measurement of SBA levels may have a clinical role as a simple noninvasive tool to assess the severity of HCV-induced liver disease. Combined with widely available laboratory parameters, SBA levels can predict disease severity with a high degree of accuracy.

The metabolic regulator PGC-1α links anti-cancer cytotoxic chemotherapy to reactivation of hepatitis B virus

Patients with chronic hepatitis B virus (HBV) infection are at an increased risk for a severe and a potentially fatal viral reactivation following anti-cancer therapy. The molecular mechanism for this induction of HBV expression is still unclear. Here, we show that treating hepatoma cell line expressing HBV with various anti-cancer cytotoxic agents results in a significant up-regulation of HBV expression. This HBV induction is at the transcriptional level and is time dependent. Interestingly, treating hepatoma cells with anti-cancer cytotoxic agents results in a robust induction of peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α), a metabolic and energy regulator that is normally induced in the liver under starvation conditions and that has been previously shown to strongly coactivate HBV transcription. Most importantly, HBV up-regulation following anti-cancer therapy depends on PGC-1α induction, because PGC-1α knock-down abolishes HBV induction. Finally, pretreatment of HBV-expressing cells with the antioxidant agent N-acetylcysteine attenuates the induction of both PGC-1α and HBV in response to anti-cancer treatment, suggesting that chemotherapy-associated PGC-1α induction is mediated by cellular oxidative stress that ultimately leads to HBV up-regulation. We conclude that cytotoxic anti-cancer chemotherapy has a direct and an immune system-independent effect on HBV gene expression, which is mediated by PGC-1α. Our results attribute to this metabolic regulator an unexpected role in linking anti-cancer treatment to HBV reactivation and make PGC-1α a potential target for future anti-HBV therapy, especially under conditions in which it is robustly induced, such as following anti-cancer treatment.

Targeting late SV40 factor: Is the achilles heel of hepatocarcinogenesis revealed?

Hepatocellular carcinoma (HCC) is a dreadful cancer and a major cause of death among patients with chronic liver disease and cirrhosis. The apparent alterations in a diversity of intracellular pathways found in HCC has set the rational for developing molecular-directed drugs that simultaneously inhibit multiple pathways, such as the multi-kinase inhibitor Sorafenib. However, recently this concept has been challenged by showing that HCC is heavily dependent on a single oncogene designated late SV-40 factor (LSF), a transcription factor that is over-expressed in liver cancer cells and that its expression is strongly correlated with tumor grade and aggressiveness. Furthermore, using an intensive screening for drugs that inhibit LSF activity, Grant et al have found a molecule designated factor quinolinone inhibitor 1 that can specifically block the ability of LSF to bind its target promoters, resulting in a massive death of HCC cells both in vitro and in vivo. The innovative findings of HCC representing “oncogene addiction” to LSF and the ability of a single molecule to block the activity of this oncogene resulting in tumor abolishment are encouraging and provide us with the hope that the “Achilles heel” of HCC has been found.