Dysregulation of hepatocyte cell cycle and cell viability by hepatitis B virus

A novel anti-HBV agent, E-CFCP, restores Hepatitis B virus (HBV)-induced senescence-associated cellular marker perturbation in human hepatocytes

Cellular senescence is a cellular state with a broad spectrum of age-related physiological conditions that can be affected by various infectious diseases and treatments. Therapy of hepatitis B virus (HBV) infection with nucleos(t)ide analogs [NA(s)] is well established and benefits many HBV-infected patients, but requires long-term, perhaps lifelong, medication. In addition to the effects of HBV infection, the effects of NA administration on hepatocellular senescence are still unclear. This study investigated how HBV infection and NA treatment influence cellular senescence in human hepatocytes and humanized-liver chimeric mice chronically infected with live HBV. HBV infection upregulates or downregulates multiple cellular markers including senescence-associated β-galactosidase (SA-β-Gal) activity and cell cycle regulatory proteins (e.g., p21^CIP1) expression level in hepatocellular nuclei and humanized-mice liver. A novel highly potent anti-HBV NA, E-CFCP, per se did not have significant disturbance on markers evaluated. Besides, E-CFCP treatment restored HBV-infected cells to their physiological phenotypes that are comparable to the HBV-uninfected cells. The results reported here demonstrate that, regardless of the mechanism(s), chronic HBV infection perturbates multiple senescence-associated markers in human hepatocytes and humanized-mice liver, but E-CFCP can restore this phenomenon.

3D human liver organoids: An in vitro platform to investigate HBV infection, replication and liver tumorigenesis

Hepatitis B Virus (HBV) infection is a leading cause of chronic liver cirrhosis and hepatocellular carcinoma (HCC) with an estimated 400 million people infected worldwide. The precise molecular mechanisms underlying HBV replication and tumorigenesis have remained largely uncharacterized due to the lack of a primary cell model to study HBV, a virus that exhibits stringent host species and cell-type specificity. Organoid technology has recently emerged as a powerful tool to investigate human diseases in a primary 3D cell-culture system that maintains the organisation and functionality of the tissue of origin. In this review, we describe the utilisation of human liver organoid platforms to study HBV. We first present the different categories of liver organoids and their demonstrated ability to support the complete HBV replication cycle. We then discuss the potential applications of liver organoids in investigating HBV infection and replication, related tumorigenesis and novel HBV-directed therapies. Liver organoids can be genetically modified, patient-derived, expanded and biobanked, thereby serving as a clinically-relevant, human, primary cell-derived platform to investigate HBV. Finally, we provide insights into the future applications of this powerful technology in the context of HBV-infection and HCC.

HBV-related hepatocarcinogenesis: the role of signalling pathways and innovative ex vivo research models

BACKGROUND

Hepatitis B virus (HBV) is the leading cause of liver cancer, but the mechanisms by which HBV causes liver cancer are poorly understood and chemotherapeutic strategies to cure liver cancer are not available. A better understanding of how HBV requisitions cellular components in the liver will identify novel therapeutic targets for HBV associated hepatocellular carcinoma (HCC).

MAIN BODY

The development of HCC involves deregulation in several cellular signalling pathways including Wnt/FZD/β-catenin, PI3K/Akt/mTOR, IRS1/IGF, and Ras/Raf/MAPK. HBV is known to dysregulate several hepatocyte pathways and cell cycle regulation resulting in HCC development. A number of these HBV induced changes are also mediated through the Wnt/FZD/β-catenin pathway. The lack of a suitable human liver model for the study of HBV has hampered research into understanding pathogenesis of HBV. Primary human hepatocytes provide one option; however, these cells are prone to losing their hepatic functionality and their ability to support HBV replication. Another approach involves induced-pluripotent stem (iPS) cell-derived hepatocytes. However, iPS technology relies on retroviruses or lentiviruses for effective gene delivery and pose the risk of activating a range of oncogenes. Liver organoids developed from patient-derived liver tissues provide a significant advance in HCC research. Liver organoids retain the characteristics of their original tissue, undergo unlimited expansion, can be differentiated into mature hepatocytes and are susceptible to natural infection with HBV.

CONCLUSION

By utilizing new ex vivo techniques like liver organoids it will become possible to develop improved and personalized therapeutic approaches that will improve HCC outcomes and potentially lead to a cure for HBV.

Unique intrahepatic transcriptomics profiles discriminate the clinical phases of a chronic HBV infection

Chronic hepatitis B is a highly heterogeneous liver disease characterized by phases with fluctuations in viral replication and progressive liver damage in some, but not all infected individuals. Despite four decades of research, insight into host determinants underlying these distinct clinical phases-immunotolerant, immune active, inactive carrier, and HBeAg-negative hepatitis-remains elusive. We performed an in-depth transcriptome analysis of archived FFPE liver biopsies of each clinical phase to address host determinants associated with the natural history. Therefore, we determined, for the first time, intrahepatic global expression profiles of well-characterized chronic HBV patients at different clinical phases. Our data, obtained by microarray, demonstrate that B cells and NK/cytotoxic-related genes in the liver, including CD19, TNFRSF13C, GZMH, and KIR2DS3, were differentially expressed across the clinical HBV phases, which was confirmed by modular analysis and also Nanostring arrays in an independent cohort. Compared to the immunotolerant phase, 92 genes were differentially expressed in the liver during the immune active phase, 46 in the inactive carrier phase, and 71 in the HBeAg-negative phase. Furthermore, our study also revealed distinctive transcription of genes associated with cell cycle activity, NF-κB signaling, cytotoxic function and mitochondrial respiration between clinical phases. Our data define for the first time using microarray unique transcriptomes in the HBV-infected liver during consecutive clinical phases. We demonstrate that fluctuations of viral loads and liver damage coincide with fluctuations in the liver transcriptome and point to functional- immune and non-immune- components contributing to the clinical phenotype in patients.

Hepatitis B virus infection and replication in a new cell culture system established by fusing HepG2 cells with primary human hepatocytes

BACKGROUND

Hepatitis B virus (HBV) infection is strictly species and tissue specific, therefore none of the cell models established previously can reproduce the natural infection process of HBV in vitro. The aim of this study was to establish a new cell line that is susceptible to HBV and can support the replication of HBV.

METHODS

A hybrid cell line was established by fusing primary human hepatocytes with HepG2 cells. The hybrid cells were incubated with HBV-positive serum for 12 hours. HBV DNA was detected by quantitative fluorescence polymerase chain reaction (QF-PCR). HBsAg (surface antigen) and HBeAg (extracellular form of core antigen) were observed by electrochemiluminescence (ECL). HBcAg (core antigen) was detected by the indirect immunofluorescence technique. HBV covalently closed circular DNA (cccDNA) was analyzed by Southern blot hybridization and quantified using real-time PCR.

RESULTS

A new cell line was established and named HepCHLine-7. The extracellular HBV DNA was observed from Day 2 and the levels ranged from 9.80 (± 0.32) × 10(2) copies/mL to 3.12 (± 0.03) × 10(4) copies/mL. Intracellular HBV DNA was detected at Day 2 after infection and the levels ranged from 7.92 (± 1.08) × 10(3) copies/mL to 5.63 (± 0.11) × 10(5) copies/mL. HBsAg in the culture medium was detected from Day 4 to Day 20. HBeAg secretion was positive from Day 5 to Day 20. HBcAg constantly showed positive signals in approximately 20% (± 0.82%) of hybrid cells. Intracellular HBV cccDNA could be detected as early as 2 days postinfection and the highest level was 15.76 (± 0.26) copies/cell.

CONCLUSION

HepCHLine-7 cells were susceptible to HBV and supported the replication of HBV. They are therefore suitable for studying the complete life cycle of HBV.

Characterization of microRNA expression profiles associated with hepatitis B virus replication and clearance in vivo and in vitro

BACKGROUND AND AIM

Alpha interferon (IFN-α) is an approved treatment for chronic hepatitis B (CHB). MicroRNA (miRNA) are currently known as a part of IFN-mediated antiviral defense. We aimed at characterizing the miRNA expression associated with hepatitis B virus (HBV) replication and IFN-mediated HBV clearance.

METHODS

We investigated the expression patterns of cellular miRNA induced by HBV replication and/or IFN-α treatment in HepG2 cells, and also analyzed the miRNA response in peripheral blood mononuclear cells in CHB patients on IFN-α treatment. The differentially expressed miRNA were verified using quantitative real-time polymerase chain reaction and an miRNA expression pattern was classified based on the final virological response.

RESULTS

A total of 223 miRNA were differentially expressed (> 1.5 folds) between the HepG2.2.15 and HepG2 cells, including 24 highly differentially expressed miRNA (> 5 folds). With 12 h of IFN-α treatment, 23 totally differentially expressed miRNA were identified in HepG2 cells; whereas only five miRNA were identified in HepG2.2.15 cells. Similar amounts of the miRNA were regulated in patients with HBeAg or non-HBeAg seroconversion; whereas levels of eight miRNA were significantly differentially expressed between the two groups.

CONCLUSIONS

HBV replication alters miRNA expression profiles and impairs IFN-inducible miRNA response in HepG2 cells. The miRNA expression pattern of peripheral blood mononuclear cells in CHB patients with IFN therapy can be associated with their therapeutic outcome.

Hepatitis B virus infection and replication in human bone marrow mesenchymal stem cells

Background

Hepatitis B virus (HBV) infection is a blood borne infectious disease that affects the liver. Human bone marrow mesenchymal stem cells (BMSCs) may serve as a cell source for adult stem cell transplantation in liver repair. However, the susceptibility of human BMSCs to HBV infection is poorly understood. The aim of this study was to investigate the infection and replication of HBV in cultures of human BMSCs.

Results

Human BMSCs were confirmed using flow cytometry. Intracellular HBV DNA was detected at d 2 after infection and maintained at relatively high levels from d 6 to d 12. The maximal level of intracellular HBV DNA was 9.37 × 10⁵ copies/mL. The extracellular HBV DNA was observed from d 3 to d 15, and the levels ranged from 3.792 × 10² copies/mL to 4.067 × 10⁵ copies/mL. HBsAg in the culture medium was detected from d 2 to d 16. HBeAg secretion was positive from d 5 to d 13. HBcAg constantly showed positive signals in approximately 7%-20% of BMSCs from 2 days after exposure. Intracellular HBV covalently closed circular DNA (cccDNA) could be detected as early as 2 days postinfection, and strong signals were obtained with increasing time.

Conclusion

HBV can infect and replicate in human BMSCs. Human BMSCs may be a useful tool for investigating HBV life-cycle and the mechanism of initial virus-cell interactions.