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Dash S, Aydin Y, Widmer KE, Nayak L. Hepatocellular Carcinoma Mechanisms Associated with Chronic HCV Infection and the Impact of Direct-Acting Antiviral Treatment. J Hepatocell Carcinoma 2020; 7:45-76. [PMID: 32346535 PMCID: PMC7167284 DOI: 10.2147/jhc.s221187] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 03/06/2020] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) infection is the major risk factor for liver cirrhosis and hepatocellular carcinoma (HCC). The mechanisms of HCC initiation, growth, and metastasis appear to be highly complex due to the decade-long interactions between the virus, immune system, and overlapping bystander effects of host metabolic liver disease. The lack of a readily accessible animal model system for HCV is a significant obstacle to understand the mechanisms of viral carcinogenesis. Traditionally, the primary prevention strategy of HCC has been to eliminate infection by antiviral therapy. The success of virus elimination by antiviral treatment is determined by the SVR when the HCV is no longer detectable in serum. Interferon-alpha (IFN-α) and its analogs, pegylated IFN-α (PEG-IFN-α) alone with ribavirin (RBV), have been the primary antiviral treatment of HCV for many years with a low cure rate. The cloning and sequencing of HCV have allowed the development of cell culture models, which accelerated antiviral drug discovery. It resulted in the selection of highly effective direct-acting antiviral (DAA)-based combination therapy that now offers incredible success in curing HCV infection in more than 95% of all patients, including those with cirrhosis. However, several emerging recent publications claim that patients who have liver cirrhosis at the time of DAAs treatment face the risk of HCC occurrence and recurrence after viral cure. This remains a substantial challenge while addressing the long-term benefit of antiviral medicine. The host-related mechanisms that drive the risk of HCC in the absence of the virus are unknown. This review describes the multifaceted mechanisms that create a tumorigenic environment during chronic HCV infection. In addition to the potential oncogenic programming that drives HCC after viral clearance by DAAs, the current status of a biomarker development for early prediction of cirrhosis regression and HCC detection post viral treatment is discussed. Since DAAs treatment does not provide full protection against reinfection or viral transmission to other individuals, the recent studies for a vaccine development are also reviewed.
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Affiliation(s)
- Srikanta Dash
- Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center, New Orleans, LA70112, USA
- Southeast Louisiana Veterans Health Care System, New Orleans, LA70119, USA
- Department of Medicine, Division of Gastroenterology, Tulane University Health Sciences Center, New Orleans, LA70112, USA
| | - Yucel Aydin
- Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center, New Orleans, LA70112, USA
| | - Kyle E Widmer
- Southeast Louisiana Veterans Health Care System, New Orleans, LA70119, USA
| | - Leela Nayak
- Southeast Louisiana Veterans Health Care System, New Orleans, LA70119, USA
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2
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Mazouz S, Boisvert M, Shoukry NH, Lamarre D. Reversing immune dysfunction and liver damage after direct-acting antiviral treatment for hepatitis C. CANADIAN LIVER JOURNAL 2018; 1:78-105. [DOI: 10.3138/canlivj.1.2.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 03/20/2018] [Indexed: 12/12/2022]
Abstract
The introduction of small molecules targeting viral functions has caused a paradigm shift in hepatitis C virus (HCV) treatment. Administration of these direct-acting antivirals (DAAs) achieves a complete cure in almost all treated patients with short-duration therapy and minimal side effects. Although this is a major improvement over the previous pegylated interferon plus ribavirin (PEG-IFNα/RBV) standard-of-care treatment for HCV, remaining questions address several aspects of the long-term benefits of DAA therapy. Interferon (IFN)-based treatment with successful outcome was associated with substantial reduction in liver disease–related mortality. However, emerging data suggest a complex picture and several confounding factors that influence the effect of both IFN-based and DAA therapies on immune restoration and limiting liver disease progression. We review current knowledge of restoration of innate and HCV-specific immune responses in DAA-mediated viral elimination in chronic HCV infection, and we identify future research directions to achieve long-term benefits in all cured patients and reduce HCV-related liver disease morbidity and mortality.
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Affiliation(s)
- Sabrina Mazouz
- Centre de Recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montréal, Québec, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
- Département de médecine, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
| | - Maude Boisvert
- Centre de Recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montréal, Québec, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
- Département de médecine, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
| | - Naglaa H Shoukry
- Centre de Recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montréal, Québec, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
- Département de médecine, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
| | - Daniel Lamarre
- Centre de Recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Montréal, Québec, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
- Département de médecine, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
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Grünvogel O, Colasanti O, Lee JY, Klöss V, Belouzard S, Reustle A, Esser-Nobis K, Hesebeck-Brinckmann J, Mutz P, Hoffmann K, Mehrabi A, Koschny R, Vondran FWR, Gotthardt D, Schnitzler P, Neumann-Haefelin C, Thimme R, Binder M, Bartenschlager R, Dubuisson J, Dalpke AH, Lohmann V. Secretion of Hepatitis C Virus Replication Intermediates Reduces Activation of Toll-Like Receptor 3 in Hepatocytes. Gastroenterology 2018. [PMID: 29535029 DOI: 10.1053/j.gastro.2018.03.020] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Hepatitis C virus (HCV) infections most often result in chronic outcomes, although the virus constantly produces replication intermediates, in particular double-stranded RNA (dsRNA), representing potent inducers of innate immunity. We aimed to characterize the fate of HCV dsRNA in hepatocyte cultures to identify mechanisms contributing to viral persistence in presence of an active innate immune response. METHODS We analyzed hepatocyte-based culture models for HCV for induction of innate immunity, secretion of virus positive- or negative-strand RNA, and viral replication using different quantification methods and microscopy techniques. Expression of pattern recognition receptors was reconstituted in hepatoma cells by lentiviral transduction. RESULTS HCV-infected cells secrete substantial amounts of virus positive- and negative-strand RNAs in extracellular vesicles (EVs), toward the apical and basolateral domain of hepatocytes. Secretion of negative-strand RNA was independent from virus production, and viral RNA secreted in EVs contained higher relative amounts of negative-strands, indicating that mostly virus dsRNA is released. A substantial part of viral replication complexes and dsRNA was found in the endosomal compartment and multivesicular bodies, indicating that secretion of HCV replication intermediates is mediated by the exosomal pathway. Block of vesicle release in HCV-positive cells increased intracellular dsRNA levels and increased activation of toll-like receptor 3, inhibiting HCV replication. CONCLUSIONS Using hepatocyte-based culture models for HCV, we found a portion of HCV dsRNA intermediates to be released from infected cells in EVs, which reduces activation of toll-like receptor 3. This represents a novel mechanism how HCV evades host immune responses, potentially contributing to viral persistence.
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Affiliation(s)
- Oliver Grünvogel
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Ombretta Colasanti
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Ji-Young Lee
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Volker Klöss
- Department of Infectious Diseases, Medical Microbiology and Hygiene, University Hospital Heidelberg, Heidelberg, Germany
| | - Sandrine Belouzard
- University Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL- Centre d'Infection et d'Immunité de Lille, France
| | - Anna Reustle
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Katharina Esser-Nobis
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | | | - Pascal Mutz
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany; Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Katrin Hoffmann
- Department of General-, Visceral- and Transplantation Surgery, University Hospital Heidelberg, Heidelberg, Germany
| | - Arianeb Mehrabi
- Department of General-, Visceral- and Transplantation Surgery, University Hospital Heidelberg, Heidelberg, Germany
| | - Ronald Koschny
- Department of Gastroenterology, Infectious Diseases and Intoxication, University Hospital Heidelberg, Heidelberg, Germany
| | - Florian W R Vondran
- Regenerative Medicine and Experimental Surgery (ReMediES), Department of General, Visceral and Transplant Surgery, Hannover Medical School, Hannover, Germany; German Center for Infection Research (DZIF), partner site Hannover-Braunschweig, Hannover, Germany
| | - Daniel Gotthardt
- Department of Gastroenterology, Infectious Diseases and Intoxication, University Hospital Heidelberg, Heidelberg, Germany
| | - Paul Schnitzler
- Department of Infectious Diseases, Virology, University of Heidelberg, Heidelberg, Germany
| | - Christoph Neumann-Haefelin
- Department of Medicine II, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg
| | - Robert Thimme
- Department of Medicine II, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg
| | - Marco Binder
- Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany; Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Jean Dubuisson
- University Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL- Centre d'Infection et d'Immunité de Lille, France
| | - Alexander H Dalpke
- Department of Infectious Diseases, Medical Microbiology and Hygiene, University Hospital Heidelberg, Heidelberg, Germany
| | - Volker Lohmann
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany.
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Liang Y, Cao X, Ding Q, Zhao Y, He Z, Zhong J. Hepatitis C virus NS4B induces the degradation of TRIF to inhibit TLR3-mediated interferon signaling pathway. PLoS Pathog 2018; 14:e1007075. [PMID: 29782532 PMCID: PMC5983870 DOI: 10.1371/journal.ppat.1007075] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 06/01/2018] [Accepted: 05/07/2018] [Indexed: 12/12/2022] Open
Abstract
Toll-like receptor 3 (TLR3) senses dsRNA intermediates produced during RNA virus replication to activate innate immune signaling pathways through adaptor protein TRIF. Many viruses have evolved strategies to block TLR3-mediated interferon signaling via targeting TRIF. Here we studied how hepatitis C virus (HCV) antagonizes the TLR3-mediated interferon signaling. We found that HCV-encoded NS4B protein inhibited TLR3-mediated interferon signaling by down-regulating TRIF protein level. Mechanism studies indicated that the downregulation of TRIF by NS4B was dependent on caspase8. NS4B transfection or HCV infection can activate caspase8 to promote TRIF degradation, leading to suppression of TLR3-mediated interferon signaling. Knockout of caspase8 can prevent TRIF degradation triggered by NS4B, thereby enhancing the TLR3-mediated interferon signaling activation in response to HCV infection. In conclusion, our work revealed a new mechanism for HCV to evade innate immune response by blocking the TLR3-mediated interferon signaling via NS4B-induced TRIF degradation.
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Affiliation(s)
- Yisha Liang
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
- ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xuezhi Cao
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Qiang Ding
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Yanan Zhao
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhenliang He
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jin Zhong
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
- ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- * E-mail:
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5
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Gondeau C, Briolotti P, Razafy F, Duret C, Rubbo PA, Helle F, Rème T, Ripault MP, Ducos J, Fabre JM, Ramos J, Pécheur EI, Larrey D, Maurel P, Daujat-Chavanieu M. In vitro infection of primary human hepatocytes by HCV-positive sera: insights on a highly relevant model. Gut 2014; 63:1490-500. [PMID: 24153249 DOI: 10.1136/gutjnl-2013-304623] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Adult primary human hepatocytes (PHHs) support the complete infection cycle of natural HCV from patients' sera. The molecular details underlying sera infectivity towards these cells remain largely unknown. Therefore, we sought to gain a deeper comprehension of these features in the most physiologically relevant culture system. DESIGN Using kinetic experiments, we defined the optimal conditions to infect PHH and explored the link between cell organisation and permissivity. Based on their infectivity, about 120 sera were classified in three groups. Concentration of 52 analytes was measured in 79 selected sera using multiplexed immunobead-based analyte profiling. RESULTS PHH permissivity towards HCV infection negatively correlated with cell polarisation and formation of functional bile canaliculi. PHH supported HCV replication for at least 2 weeks with de novo virus production. Depending on their reactivity, sera could be classified in three groups of high, intermediate or low infectivity toward PHH. Infectivity could not be predicted based on the donors' clinical characteristics, viral load or genotype. Interestingly, highly infectious sera displayed a specific cytokine profile with low levels of most of the 52 tested analytes. Among them, 24 cytokines/growth factors could impact hepatocyte biology and infection efficiency. CONCLUSIONS We identified critical factors leading to efficient PHH infection by HCV sera in vitro. Overall, we showed that this cellular model provides a useful tool for studying the mechanism of HCV infection in its natural host cell, selecting highly infectious isolates, and determining the potency of drugs towards various HCV strains.
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Affiliation(s)
- Claire Gondeau
- INSERM U1040, Montpellier, France Université Montpellier 1, Montpellier, France
| | - Philippe Briolotti
- INSERM U1040, Montpellier, France Université Montpellier 1, Montpellier, France
| | - Francia Razafy
- INSERM U1040, Montpellier, France Université Montpellier 1, Montpellier, France
| | - Cédric Duret
- INSERM U1040, Montpellier, France Université Montpellier 1, Montpellier, France
| | - Pierre-Alain Rubbo
- Université Montpellier 1, Montpellier, France INSERM U1058, Montpellier, France
| | - François Helle
- EA4294, Laboratoire de Virologie, Centre Hospitalier Universitaire et Université de Picardie Jules Verne, Amiens, France
| | - Thierry Rème
- INSERM U1040, Montpellier, France Université Montpellier 1, Montpellier, France
| | - Marie-Pierre Ripault
- Department of Hepato-gastroenterology A, Hospital Saint Eloi, CHU Montpellier, Montpellier, France
| | - Jacques Ducos
- INSERM U1058, Montpellier, France Département de Bactériologie-Virologie, CHU de Montpellier, Montpellier, France
| | - Jean-Michel Fabre
- Department of Digestive Surgery, Hospital Saint Eloi, CHU Montpellier, France
| | - Jeanne Ramos
- Pathological anatomy department, CHU Gui de Chauliac, Montpellier, France
| | - Eve-Isabelle Pécheur
- UMR INSERM 1052/CNRS 5286, Centre de Recherche en Cancérologie de Lyon, Université de Lyon, Lyon, France
| | - Dominique Larrey
- INSERM U1040, Montpellier, France Department of Hepato-gastroenterology A, Hospital Saint Eloi, CHU Montpellier, Montpellier, France
| | - Patrick Maurel
- INSERM U1040, Montpellier, France Université Montpellier 1, Montpellier, France
| | - Martine Daujat-Chavanieu
- INSERM U1040, Montpellier, France Université Montpellier 1, Montpellier, France CHU Saint Eloi, Institute of Research in Biotherapy, Montpellier, France
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Khanlari Z, Sabahi F, Hosseini SY, Ghaderi M. HCV NS3 Blocking Effect on IFN Induced ISGs Like Viperin and IL28 With and Without NS4A. HEPATITIS MONTHLY 2014; 14:e17822. [PMID: 24976840 PMCID: PMC4071354 DOI: 10.5812/hepatmon.17822] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 03/09/2014] [Accepted: 04/13/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND Hepatitis C virus (HCV) is able to down-regulate innate immune response. It is important to know the immune pathways that this virus interacts with. HCV non-structural protein 3 (NS3) plays an important role in this viral feature. HCV NS3 protein could affect the expression of antiviral protein such as viperin, and interleukin 28whichare important proteins in antiviral response. OBJECTIVES HCV has developed different mechanisms to maintain a persistent infection, especially by disrupting type I interferon response and subsequent suppression of expression of Interferon stimulatory genes (ISGs). Viperin, a member of ISGs, is considered as a host antiviral protein, which interferes with viral replication. Since it is a good target for some viruses to evade host responses, it is interesting to study if HCV has evolved a mechanism to interfere with this member of ISGs. MATERIALS AND METHODS We evaluated the impact of NS3, NS3/4A and a mutated nonfunctional NS3 on ISGs expression such as viperin and IL-28 after the induction of IFN signaling Jak-STAT pathway using IFN-. RESULTS NS3 protein disrupted the expressions of viperin gene and IL-28, an inducer for the expression of ISGs and viperin itself. By comparing the roles of NS3 and NS3/4A protease activities in suppressing the innate immune responses, we also showed that NS3 (without NS4A) has the ability to down-regulate ISGs expression, similar to that of NS3/4A. CONCLUSIONS ISGs expression is impeded by NS3 protease activity and its interaction with Jak-STAT pathway proteins. In addition, the NS3/4A substrates spectrum seems to be similar to those of NS3.
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Affiliation(s)
- Zahra Khanlari
- Department of Medical Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran
| | - Farzaneh Sabahi
- Department of Medical Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran
- Corresponding Author: Farzaneh Sabahi, Department of Medical Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran. Tel: +98-2182883880, Fax: +98-2182884555, E-mail:
| | - Seyed Younes Hosseini
- Gastroenterohepatology Research Center, Shiraz University of Medical Sciences, Shiraz, IR Iran
| | - Mostafa Ghaderi
- Department of Medical Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran
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Bahgat MM. Interaction Between the Neglected Tropical Disease Human Schistosomiasis and HCV Infection in Egypt: a Puzzling Relationship. J Clin Transl Hepatol 2014; 2:134-9. [PMID: 26356794 PMCID: PMC4521266 DOI: 10.14218/jcth.2013.00028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Revised: 02/21/2014] [Accepted: 02/26/2014] [Indexed: 02/06/2023] Open
Abstract
Egypt has the highest prevalence of chronic hepatitis C virus (HCV) infection and seropositivity worldwide, and it has been proposed that this enhanced susceptibility to HCV is related to coinfection with schistosomiasis. Although currently, there are no studies regarding the actual prevalence of both human schistosomiasis and schistosomiasis/HCV coinfection evidences strongly support that eliminating human schistosomiasis from Egypt is necessary to reduce both HCV prevalence and liver pathology. The present review highlights the significant impact of the neglected tropical disease human schistosomiasis on both susceptibility of Egyptians to HCV coinfection, severity of the resulting liver pathology, and poor response to antiviral therapy. The immune evasion mechanisms exerted by the HCV-NS3/4A protease domain, and the possible impact of immune evasion mechanisms exerted by proteases of larval, worm and egg stages of the parasite Schistosoma on human susceptibility to HCV infection are discussed. In addition, schistosome immune evasion mechanisms may include immunosuppression that in turn prevents clearance of HCV viremia and leads to relapsing HCV infection and severe liver pathology. I propose the generation of a replicon system from the most prevailing genotype (HCV-4a) in Egypt and establishing its replication on hepatoplastoma or immune cells in presence of bilharzial antigens. Finally, the use of a humanized small animal model that can acquire both HCV and S. mansoni infections will be important to further understand in real time the impact of coinfection on both the immune system and liver pathology.
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Affiliation(s)
- Mahmoud M. Bahgat
- Immunology and Infectious Diseases Group, Therapeutic Chemistry Department, the Centre of Excellence for Advanced Sciences, the National Research Centre, Dokki, Cairo, Egypt
- Research Group of Biomarkers for Infection and Immunity, Institute of Experimental Infection Research, TWINCORE Centre for Experimental and Clinical Infection Research, Hannover, Germany
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8
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Amanzada A, Kopp W, Spengler U, Ramadori G, Mihm S. Interferon-λ4 (IFNL4) transcript expression in human liver tissue samples. PLoS One 2013; 8:e84026. [PMID: 24376784 PMCID: PMC3869873 DOI: 10.1371/journal.pone.0084026] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 11/18/2013] [Indexed: 01/22/2023] Open
Abstract
Eradication of hepatitis C virus (HCV) infection, both spontaneous and treatment-induced, is marked by the wildtype allele C of a single nucleotide polymorphism upstream of the IL28B gene, rs12979860. This favorable allele was recently described to be in linkage disequilibrium with the wildtype allele TT of a dinucleotide polymorphism, ss469415590, located within a new protein-coding gene. While the TT allele introduces a frame-shift and disrupts the open reading frame, only the variant allele, ΔG, creates a novel type III interferon (IFN) protein, IFN-λ4/IFNL4. Absence of IFNL4 is thus supposed to favor resolution of HCV infection. As to date IFNL4 mRNA transcription has only been investigated in polyI:C-stimulated primary human hepatocytes and not yet in HCV infection in vivo, this study analyzed IFNL4 mRNA expression in human liver biopsy specimens. Samples were obtained from patients with a broad panel of disorders including no liver disease, liver diseases of non-viral etiology, chronic hepatitis B and chronic hepatitis C. Hepatic IFNL4 transcripts were detectable exclusively in a subgroup of chronic hepatitis C patients (24/45). Their amounts were positively related to liver HCV RNA copy numbers (p = 0.0023, r = 0.56) suggesting that the hepatic viral load influences IFNL4 transcription irrespective of IFNL4 governing genotype. Both, the IFNL4 creating allele ΔG (p<0.0001) and actual IFNL4 transcription (p = 0.0015) were found to be correlated to the activation of IFN stimulatory genes (ISGs). By contrast, IFNL4 ss469415590 genotypes were not found to be related to IFN-λ2/3/IL28 or IFN-λ1/IL29 gene expression. In conclusion, this study is the first report on intrahepatic transcript levels of the recently discovered IFNL4 gene. Data indicate that HCV infection in particular might activate IFNL4 transcription in the liver. It provides a possible explanation as to why hepatitis C patients show ISG stimulation in their livers in the apparent absence of an induction of other IFN subtypes.
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Affiliation(s)
- Ahmad Amanzada
- Department of Gastroenterology and Endocrinology, University Medical Center Goettingen, Goettingen, Germany
| | - Waltraut Kopp
- Department of Gastroenterology and Endocrinology, University Medical Center Goettingen, Goettingen, Germany
| | - Ulrich Spengler
- Department of General Internal Medicine, University Hospital Bonn, Bonn, Germany
| | - Giuliano Ramadori
- Department of Gastroenterology and Endocrinology, University Medical Center Goettingen, Goettingen, Germany
| | - Sabine Mihm
- Department of Gastroenterology and Endocrinology, University Medical Center Goettingen, Goettingen, Germany
- * E-mail:
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9
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Kalkeri G, Lin C, Gopilan J, Sloan K, Rijnbrand R, Kwong AD. Restoration of the activated Rig-I pathway in hepatitis C virus (HCV) replicon cells by HCV protease, polymerase, and NS5A inhibitors in vitro at clinically relevant concentrations. Antimicrob Agents Chemother 2013; 57:4417-26. [PMID: 23836176 PMCID: PMC3754339 DOI: 10.1128/aac.00399-13] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 06/19/2013] [Indexed: 02/07/2023] Open
Abstract
Development of persistent hepatitis C virus (HCV) infection may be mediated by HCV NS3 · 4A protease-dependent inhibition of host innate immunity. When double-stranded RNA (dsRNA) is detected in virus-infected cells, host innate immunity mounts an antiviral response by upregulating production of type I interferons (α/β interferon [IFN-α/β]); HCV counters by cleaving the IFN-β stimulator 1 (IPS-1) adaptor protein, decreasing synthesis of IFN-α/β. We evaluated HCV protease (telaprevir, boceprevir, and TMC435350), polymerase (HCV-796 and VX-222), and NS5A (BMS-790052) inhibitors for the ability to restore IPS-1-mediated Rig-I signaling by measuring Sendai virus-induced IFN-β promoter activation in HCV replicon cells after various exposure durations. All direct-acting HCV antivirals tested restored mitochondrial localization of IPS-1 and rescued Sendai virus-induced IRF3 signaling after 7 days by inhibiting HCV replication, thereby reducing the abundance of HCV NS3 · 4A protease. With 4-day treatment, HCV protease inhibitors, but not polymerase inhibitors, restored mitochondrial localization of IPS-1 and rescued IFN-β promoter activation in the presence of equivalent levels of NS3 protein in protease or polymerase inhibitor-treated cells. The concentrations of HCV protease and polymerase inhibitors needed to rescue IRF3-mediated signaling in vitro were in the range of those observed in vivo in the plasma of treated HCV patients. These findings suggest that (i) HCV protease, polymerase, and NS5A inhibitors can restore virus-induced IRF3 signaling by inhibiting viral replication, thereby reducing NS3 protease levels, and (ii) HCV protease inhibitors can restore innate immunity by directly inhibiting NS3 protease-mediated cleavage of IPS-1 at clinically achievable concentrations.
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Affiliation(s)
- Gururaj Kalkeri
- Vertex Pharmaceuticals Incorporated, Cambridge, Massachusetts, USA.
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Keyvani H, Fazlalipour M, Monavari SHR, Mollaie HR. Hepatitis C Virus - Proteins, Diagnosis, Treatment and New Approaches for Vaccine Development. Asian Pac J Cancer Prev 2012. [DOI: 10.7314/apjcp.2012.13.12.5917] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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12
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Kohjima M, Enjoji M, Yoshimoto T, Yada R, Fujino T, Aoyagi Y, Fukushima N, Fukuizumi K, Harada N, Yada M, Kato M, Kotoh K, Nakashima M, Sakamoto N, Tanaka Y, Nakamuta M. Add-on therapy of pitavastatin and eicosapentaenoic acid improves outcome of peginterferon plus ribavirin treatment for chronic hepatitis C. J Med Virol 2012; 85:250-60. [PMID: 23161429 DOI: 10.1002/jmv.23464] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2012] [Indexed: 12/19/2022]
Abstract
Despite the use of pegylated-interferon (peg-IFN) plus ribavirin combination therapy, many patients infected with hepatitis C virus (HCV)-1b remain HCV-positive. To determine whether addition of pitavastatin and eicosapentaenoic acid (EPA) is beneficial, the "add-on" therapy option (add-on group) was compared retrospectively with unmodified peg-IFN/ribavirin therapy (standard group). Association of host- or virus-related factors with sustained virological response was assessed. In HCV replicon cells, the effects of pitavastatin and/or EPA on HCV replication and expression of innate-immunity- and lipid-metabolism-associated genes were investigated. In patients infected with HCV-1b, sustained virological response rates were significantly higher in the add-on than standard group. In both groups, sustained virological response rates were significantly higher in patients with genotype TT of IL-28B (rs8099917) than in those with non-TT genotype. Among the patients with non-TT genotype, sustained virological response rates were markedly higher in the add-on than standard group. By multivariate analysis, genome variation of IL28B but not add-on therapy remained as a predictive factor of sustained virological response. In replicon cells, pitavastatin and EPA suppressed HCV replication. Activation of innate immunity was obvious in pitavastatin-treated cells and EPA suppressed the expression of sterol regulatory element binding protein-1c and low-density lipoprotein receptor. Addition of pitavastatin and EPA to peg-IFN/ribavirin treatment improved sustained virological response in patients infected with HCV-1b. Genotype variation of IL-28B is a strong predictive factor in add-on therapy.
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Affiliation(s)
- Motoyuki Kohjima
- Department of Gastroenterology, Kyushu Medical Center, Fukuoka, Japan
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13
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Es-Saad S, Tremblay N, Baril M, Lamarre D. Regulators of innate immunity as novel targets for panviral therapeutics. Curr Opin Virol 2012; 2:622-8. [PMID: 23017246 PMCID: PMC7102864 DOI: 10.1016/j.coviro.2012.08.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 08/30/2012] [Indexed: 12/21/2022]
Abstract
Interferons (IFNs) have long been used as an immunomodulatory therapy for a large array of acute and chronic viral infections. However, IFN therapies have been plagued by severe side effects. The discovery of pathogen recognition receptors (PRR) rejuvenated the interest for immunomodulatory therapies. The successes obtained with Toll-like receptor (TLR) agonists in activating immune cells and as adjuvant for prophylactic vaccines against different viruses paved the way to targeted immunomodulatory therapy. Better characterization of pathogen-induced immune disorders and newly discovered regulators of innate immunity have now the potential to specifically withdraw prevailing subversion mechanisms and to transform antiviral treatments by introducing panviral therapeutics with less adverse effects than IFN therapies.
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Affiliation(s)
- Salwa Es-Saad
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Montréal, Québec, Canada
| | - Nicolas Tremblay
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Montréal, Québec, Canada
| | - Martin Baril
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Montréal, Québec, Canada
| | - Daniel Lamarre
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Montréal, Québec, Canada
- Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada
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14
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Ding Q, Huang B, Lu J, Liu YJ, Zhong J. Hepatitis C virus NS3/4A protease blocks IL-28 production. Eur J Immunol 2012; 42:2374-82. [PMID: 22685015 DOI: 10.1002/eji.201242388] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Type I interferons (IFNs), including IFN-α, -β, and -ω, play a critical role in innate immune responses against viral infection. IFN-λ, including IL-29, IL-28A, and IL-28B, recently identified as a new subfamily of IFN named type III IFN, has also been demonstrated to suppress virus replication in vitro and in vivo. However, the molecular mechanisms that regulate the induction of type III IFNs during viral infection remain elusive. Here, we demonstrate that IL-28 (IFN-λ 2/3) IFN production, similar to type I IFN, represents a primary and direct host response to HCV genomic RNA transfection. IL-28 (IFN-λ2/3) induction by HCV genomic RNA was dependent upon the activation of NF-κB and IRF3. We identified a minimal IL-28 promoter region consisting of putative NF-κB and IRF3-binding sites. Furthermore, we showed that HCV infection can inhibit HCV genomic RNA-induced IL-28 expression, and that the viral NS3/4A protease activity was responsible for this inhibitory effect. Our results present important evidence for the control of type III IFN response by HCV, and shed more light on the molecular mechanisms underlying the persistence of HCV infection.
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MESH Headings
- 3' Untranslated Regions
- Binding Sites
- DEAD Box Protein 58
- DEAD-box RNA Helicases/genetics
- DEAD-box RNA Helicases/immunology
- DEAD-box RNA Helicases/metabolism
- Genome, Viral
- Hep G2 Cells
- Hepacivirus/enzymology
- Hepacivirus/genetics
- Hepacivirus/immunology
- Hepatitis C, Chronic/immunology
- Hepatitis C, Chronic/virology
- Humans
- Immunity, Innate/genetics
- Immunity, Innate/immunology
- Interferon Regulatory Factor-3/genetics
- Interferon Regulatory Factor-3/immunology
- Interferon Regulatory Factor-3/metabolism
- Interferon Type I/genetics
- Interferon Type I/immunology
- Interferon Type I/metabolism
- Interferons
- Interleukins/biosynthesis
- Interleukins/genetics
- Interleukins/immunology
- Interleukins/metabolism
- NF-kappa B/genetics
- NF-kappa B/immunology
- NF-kappa B/metabolism
- Promoter Regions, Genetic
- RNA, Viral/genetics
- RNA, Viral/immunology
- Receptors, Immunologic
- Transcriptional Activation
- Tumor Cells, Cultured
- Up-Regulation
- Viral Nonstructural Proteins/genetics
- Viral Nonstructural Proteins/immunology
- Viral Nonstructural Proteins/metabolism
- Virus Replication/genetics
- Virus Replication/immunology
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Affiliation(s)
- Qiang Ding
- Unit of Viral Hepatitis, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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15
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Li K, Lemon SM. Innate immune responses in hepatitis C virus infection. Semin Immunopathol 2012; 35:53-72. [PMID: 22868377 DOI: 10.1007/s00281-012-0332-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Accepted: 07/05/2012] [Indexed: 12/14/2022]
Abstract
Hepatitis C virus (HCV) is a major causative agent of chronic hepatitis and hepatocellular carcinoma worldwide and thus poses a significant public health threat. A hallmark of HCV infection is the extraordinary ability of the virus to persist in a majority of infected people. Innate immune responses represent the front line of defense of the human body against HCV immediately after infection. They also play a crucial role in orchestrating subsequent HCV-specific adaptive immunity that is pivotal for viral clearance. Accumulating evidence suggests that the host has evolved multifaceted innate immune mechanisms to sense HCV infection and elicit defense responses, while HCV has developed elaborate strategies to circumvent many of these. Defining the interplay of HCV with host innate immunity reveals mechanistic insights into hepatitis C pathogenesis and informs approaches to therapy. In this review, we summarize recent advances in understanding innate immune responses to HCV infection, focusing on induction and effector mechanisms of the interferon antiviral response as well as the evasion strategies of HCV.
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Affiliation(s)
- Kui Li
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, USA
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16
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Zhou XL, Sullivan GJ, Sun P, Park IH. Humanized murine model for HBV and HCV using human induced pluripotent stem cells. Arch Pharm Res 2012; 35:261-9. [PMID: 22370780 DOI: 10.1007/s12272-012-0206-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 11/17/2011] [Accepted: 11/21/2011] [Indexed: 12/23/2022]
Abstract
Infection of hepatitis B virus (HBV) and hepatitis C virus (HCV) results in heterogeneous outcomes from acute asymptomatic infection to chronic infection leading to cirrhosis and hepatocellular carcinoma (HCC). In vitro models using animal hepatocytes, human HCC cell lines, or in vivo transgenic mouse models have contributed invaluably to understanding the pathogenesis of HBV and HCV. A humanized mouse model made by reconstitution of human primary hepatocytes in the liver of the immunodeficient mouse provides a novel experimental opportunity which mimics the in vivo growth of the human hepatocytes. The limited access to primary human hepatocytes necessitated the search for other cellular sources, such as pluripotent stem cells. Human embryonic stem cells (hESCs) have the features of self-renewal and pluripotency and differentiate into cells of all three germ layers, including hepatocytes. Humaninduced pluripotent stem cells (iPSCs) derived from the patient's or individual's own cells provide a novel opportunity to generate hepatocyte-like cells with the defined genetic composition. Here, we will review the current perspective of the models used for HBV and HCV study, and introduce the personalized mouse model using human iPSCs. This novel mouse model will facilitate the direct investigation of HBV and HCV in human hepatocytes as well as probing the genetic influence on the susceptibility of hepatocytes to HBV and HCV.
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Affiliation(s)
- Xiao-Ling Zhou
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06520, USA
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17
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Jouan L, Chatel-Chaix L, Melançon P, Rodrigue-Gervais IG, Raymond VA, Selliah S, Bilodeau M, Grandvaux N, Lamarre D. Targeted impairment of innate antiviral responses in the liver of chronic hepatitis C patients. J Hepatol 2012; 56:70-7. [PMID: 21835140 DOI: 10.1016/j.jhep.2011.07.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Revised: 07/12/2011] [Accepted: 07/14/2011] [Indexed: 01/01/2023]
Abstract
BACKGROUND & AIMS Innate sensing of viral infection activates a global defense response including type I interferon (IFN) and IFN-stimulated genes (ISGs) expression. We previously reported that HCV NS3/4A protease, an essential protein in viral polyprotein processing, can abrogate antiviral signaling pathways and effectors' response when ectopically expressed in human hepatocytes by cleaving antiviral adaptor CARDIF. However, whether HCV mediates evasion of innate immunity in patients with chronic infection remains unclear. METHODS In this study, paired liver biopsies and corresponding purified hepatocytes of chronic hepatitis C patients and controls were subjected to transcriptional analysis of selected innate immune genes and to CARDIF protein detection. RESULTS We report that an antiviral response is largely supported by infected hepatocytes as demonstrated by upregulation of the representative antiviral genes ISG15, ISG56, and OASL as well as chemokines genes CXCL9, CXCL10, and CXCL11 measured in both HCV-derived liver biopsies and hepatocytes; that the mRNA levels of these indicator ISGs correlate inversely with HCV RNA level; and more importantly that expression of the early responsive IRF3-dependent genes type I IFNβ, type III IL28A/IL29, and chemokine CCL5 are severely compromised and associated to a global decrease of CARDIF adaptor in infected hepatocytes. CONCLUSIONS Altogether the data argue for a strong viral strategy that counteracts the host's early antiviral response of hepatocytes from chronic patients without impairing ISGs induced via classical IFN pathway.
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Affiliation(s)
- Loubna Jouan
- Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Québec, Canada H3T 1J4
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18
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Yang D, Liu N, Zuo C, Lei S, Wu X, Zhou F, Liu C, Zhu H. Innate host response in primary human hepatocytes with hepatitis C virus infection. PLoS One 2011; 6:e27552. [PMID: 22087337 PMCID: PMC3210809 DOI: 10.1371/journal.pone.0027552] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Accepted: 10/19/2011] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND AIM The interaction between hepatitis C virus (HCV) and innate antiviral defense systems in primary human hepatocytes is not well understood. The objective of this study is to examine how primary human hepatocytes response to HCV infection. METHODS An infectious HCV isolate JFH1 was used to infect isolated primary human hepatocytes. HCV RNA or NS5A protein in the cells was detected by real-time PCR or immunofluorescence staining respectively. Apoptosis was examined with flow cytometry. Mechanisms of HCV-induced IFN-β expression and apoptosis were determined. RESULTS Primary human hepatocytes were susceptible to JFH1 virus and released infectious virus. IFN-α inhibited viral RNA replication in the cells. IFN-β and interferon-stimulated genes were induced in the cells during acute infection. HCV infection induced apoptosis of primary human hepatocytes through the TRAIL-mediated pathway. Silencing RIG-I expression in primary human hepatocytes inhibited IFN-β and TRAIL expression and blocked apoptosis of the cells, which facilitated viral RNA replication in the cells. Moreover, HCV NS34A protein inhibited viral induced IFN-β expression in primary human hepatocytes. CONCLUSION Innate host response is intact in HCV-infected primary human hepatocytes. RIG-I plays a key role in the induction of IFN and TRAIL by viruses and apoptosis of primary human hepatocytes via activation of the TRAIL-mediated pathway. HCV NS34A protein appears to be capable of disrupting the innate antiviral host responses in primary human hepatocytes. Our study provides a novel mechanism by which primary human hepatocytes respond to natural HCV infection.
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Affiliation(s)
- Darong Yang
- Department of Molecular Medicine, College of Biology of Hunan University, Changsha, China
- State Key Laboratory of Chem/Biosensesing and Chemometrics, Hunan University, Changsha, China
| | - Nianli Liu
- Department of Molecular Medicine, College of Biology of Hunan University, Changsha, China
- State Key Laboratory of Chem/Biosensesing and Chemometrics, Hunan University, Changsha, China
| | - Chaohui Zuo
- Research Center of Cancer Prevention and Treatment of Hunan University and Hunan Provincial Tumor Hospital, Hunan Provincial Tumor Hospital, Changsha, China
| | - Shoahua Lei
- Department of Molecular Medicine, College of Biology of Hunan University, Changsha, China
- State Key Laboratory of Chem/Biosensesing and Chemometrics, Hunan University, Changsha, China
| | - Xinjiao Wu
- Department of Molecular Medicine, College of Biology of Hunan University, Changsha, China
- State Key Laboratory of Chem/Biosensesing and Chemometrics, Hunan University, Changsha, China
| | - Fei Zhou
- Department of Molecular Medicine, College of Biology of Hunan University, Changsha, China
- State Key Laboratory of Chem/Biosensesing and Chemometrics, Hunan University, Changsha, China
| | - Chen Liu
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida, United States of America
| | - Haizhen Zhu
- Department of Molecular Medicine, College of Biology of Hunan University, Changsha, China
- State Key Laboratory of Chem/Biosensesing and Chemometrics, Hunan University, Changsha, China
- Research Center of Cancer Prevention and Treatment of Hunan University and Hunan Provincial Tumor Hospital, Hunan Provincial Tumor Hospital, Changsha, China
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19
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Huang Y, Tong S, Tai AW, Hussain M, Lok ASF. Hepatitis B virus core promoter mutations contribute to hepatocarcinogenesis by deregulating SKP2 and its target, p21. Gastroenterology 2011; 141:1412-21, 1421.e1-5. [PMID: 21704589 PMCID: PMC3186859 DOI: 10.1053/j.gastro.2011.06.048] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 06/09/2011] [Accepted: 06/13/2011] [Indexed: 12/19/2022]
Abstract
BACKGROUND & AIMS Clinical studies have associated hepatitis B virus core promoter (CP) mutations with an increased risk of hepatocellular carcinoma. The CP region overlaps with the HBV X (HBx) gene, which has been implicated in hepatocarcinogenesis. The cyclin kinase inhibitor p21WAF1/CIP1 is an important regulator of cell cycle progression and proliferation. We determined whether HBx mutants that result from mutations in the CP deregulate p21 and these processes. METHODS We constructed a series of HBx mutants with changes in the CP region that correspond to A1762T/G1764A (TA), T1753A, T1768A, or a combination of these (combo) and expressed them, along with wild-type HBx under control of its endogenous promoter, in primary human hepatocytes (PHHs) and HepG2 cells. We then analyzed the effects of CP mutations on expression and degradation of p21 and the effects on cell cycle progression and proliferation. RESULTS The combo mutant decreased levels of p21 and increased cyclin E expression in PHHs and HepG2 cells. The combo mutant, but not HBx with single or double CP mutations, accelerated p21 degradation in HepG2 cells. The combo mutant increased expression of S-phase kinase-associated protein 2 (SKP2) in PHHs and Huh7 cells. Silencing of SKP2 abrogated the effects of CP mutations on p21 expression. The kinetics of p21 expression correlated with changes in cell cycle distribution. The combo mutant accelerated cell cycle progression; p21 overexpression restored G1 arrest. CONCLUSIONS HBx mutants with changes that correspond to a combination of CP mutations up-regulate SKP2, which then down-regulates p21 via ubiquitin-mediated proteasomal degradation. CP mutations might increase the risk of hepatocellular carcinoma via this pathway.
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Affiliation(s)
- Yuehua Huang
- Division of Gastroenterology and Hepatology, University of Michigan Health Systems, Ann Arbor, MI, USA
| | - Shuping Tong
- Liver Research Center, Rhode Island Hospital and Brown Medical School, Providence, RI, USA
| | - Andrew W. Tai
- Division of Gastroenterology and Hepatology, University of Michigan Health Systems, Ann Arbor, MI, USA,Division of Gastroenterology, Ann Arbor Veterans Administration Health Systems, Ann Arbor, MI, USA
| | - Munira Hussain
- Division of Gastroenterology and Hepatology, University of Michigan Health Systems, Ann Arbor, MI, USA
| | - Anna SF Lok
- Division of Gastroenterology and Hepatology, University of Michigan Health Systems, Ann Arbor, MI, USA
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20
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Abstract
Persistent hepatitis C virus infection is associated with progressive hepatic fibrosis and liver cancer. Acute infection evokes several distinct innate immune responses, but these are partially or completely countered by the virus. Hepatitis C virus proteins serve dual functions in replication and immune evasion, acting to disrupt cellular signaling pathways leading to interferon synthesis, subvert Jak-STAT signaling to limit expression of interferon-stimulated genes, and block antiviral activities of interferon-stimulated genes. The net effect is a multilayered evasion of innate immunity, which negatively influences the subsequent development of antigen-specific adaptive immunity, thereby contributing to virus persistence and resistance to therapy.
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Affiliation(s)
- Stanley M. Lemon
- From the Division of Infectious Disease, Department of Medicine, Center for Translational Immunology, Inflammatory Diseases Institute, Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7030
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