OBJECTIVETo investigate the role of the host-encoded silent information regulator 1 (SIRT1) on hepatocytes' lipid metabolism under conditions of hepatitis C virus (HCV) infection and assess its potential effects on virus replication in vitro.

METHODSThe Huh-7.5 human hepatocyte cell line was used as the control group and Huh-7.5 cells stably expressing the HCV replicon (Huh7.5-HCV) were used as the experimental group. Effects of interferon (IFN) treatment and activation of SIRT1 by resveratrol were also observed. The mRNA and protein expression levels of SIRT1 were detected by real time (q)PCR and western blotting. Effects on SIRT1 protein activity were tested by measuring the levels of reactive oxygen species (ROS) and the nicotinamide adenine dinucleotide (NAD+)/beta-nicotinamide adenine dinucleotide, reduced (NADH) by flow cytometry and chromatometry, and the levels of triacylglycerol (TG), total cholesterol (TC), and fatty acid beta oxidation rate by enzymatic analysis and liquid scintillation counting. Effects on mRNA expression of SIRT1 downstream lipid-metabolism genes were measured by qPCR.

RESULTSThe Huh7.5-HCV cells had a significantly higher level of ROS (3.8+/-0.5 vs. Huh-7.5: 1.0+/-0.2; t = 12.736, P less than 0.01) but significantly lower levels of NAD+/NADH (0.03+/-0.01 vs. 0.12+/-0.03; t = 6.971, P less than 0.01), SIRT1 activity (0.3+/-0.1 vs. 1.0+/-0.2, 0.9+/-0.2, F = 6.766, P less than 0.01), SIRT1 mRNA (0.4+/-0.1 vs. 1.0+/-0.3, 0.9+/-0.2, F = 5.864, P less than 0.01), and SIRT1 protein (0.3+/-0.1 vs. 0.8+/-0.2, 0.9+/-0.2, F = 5.419, P less than 0.01). The lower levels of SIRT1 in Huh7.5-HCV cells accompanied decreased phosphorylation of the forkhead box O1 (FoxO1), which not only up-regulated the downstream genes of SREBP-1c, FAS, ACC, SREBP-2, HMGR and HMGS (which increased fatty acid synthesis) but also down-regulated the downstream genes of PPAR and CPT1A genes (which decreased fatty acid beta oxidation). IFN treatment restored all of the aforementioned changes. Resveratrol-induced SIRT activation improved the perturbations in lipid metabolism pathways, as evidenced by an increase in fatty acid beta oxidation and a decrease in TG and TC synthesis, as well as inhibited HCV replication.

CONCLUSIONHCV may decrease the NAD+/NADH ratio in hepatocytes, leading to a down-regulation of SIRT1 activity and expression and perturbing the downstream expression profile of lipid metabolism-related factors, ultimately causing lipid metabolism disorders and establishing a permissive intracellular environment for HCV replication.

Cell Line ; Hepacivirus ; physiology ; Hepatocytes ; metabolism ; virology ; Humans ; Lipid Metabolism Disorders ; etiology ; metabolism ; Sirtuin 1 ; metabolism ; Triglycerides ; metabolism ; Virus Replication

Animals ; Apoptosis ; Carcinoma, Hepatocellular ; pathology ; virology ; Cell Line, Tumor ; Cell Proliferation ; Hepatitis B virus ; Hepatocytes ; pathology ; virology ; Humans ; Liver Neoplasms ; pathology ; virology ; Trans-Activators ; genetics ; metabolism ; physiology

OBJECTIVETo study the influence of hepatitis B virus (HBV) replication and expressions of different viral genes on CDC37 level in hepatocytes.

METHODSWe amplified and cloned 6 HBV genes (P, preS1, preS2, S, C and X) into pCMV expression vectors, which were transfected in Huh7 and HepG2 hepatoma cell lines, and CDC37 expression level in the cells was detected using Western blotting. Wealso cloned the promoter sequence of CDC37 into pGL3 vector, and co-transfected pGL3 with pCMV recombinant plasmids into Huh7 and HepG2 cells and the fluorescent signals were detected. To study the influence of HBV replication on CDC37 expression, we constructed 1.28-copy overlength genomes of HBV genotypes B, C, D and CD recombinant. The overlength HBV genomes were transformed into Adeasier-1 cells for recombination and into 293 cells for packaging. Huh7 and HepG2 cell lines infected with the packaged HBV recombinant adenoviruses were examined for CDC37 expression with Western blotting.

RESULTSWestern blotting showed that the expression of different HBV genes did not obviously affect the protein level of CDC37 in the hepatocytes. The protein expression of HBV genes had no effect on the activity of CDC37 promoter. Huh7 and HepG2 cells infected with 1.28-copy HBV replicon showed no significant changes in the expression level of CDC37.

CONCLUSIONHBV replication and its gene expression have no effect on the level of CDC37 in hepatocytes in vitro.

Adenoviridae ; Cell Cycle Proteins ; metabolism ; Chaperonins ; metabolism ; Gene Expression Regulation, Viral ; Genetic Vectors ; Hep G2 Cells ; Hepatitis B virus ; genetics ; physiology ; Hepatocytes ; virology ; Humans ; Transfection ; Virus Replication

OBJECTIVEIn the present study, we systemically evaluated the ability of two bioactive compounds from traditional Chinese medicine, celastrol and pristimerin, to enhance recombinant adeno-associated virus (rAAV) serotype vector-mediated transgene expression both in human cell lines in vitro, and in murine hepatocytes in vivo.

METHODSHuman cell lines were infected with rAAV vectors with either mock treatment or treatment with celastrol or pristimerin. The transgene expression, percentage of nuclear translocated viral genomes and the ubiquitination of intracellular proteins were investigated post-treatment. In addition, nonobese diabetic/severe combined immunodeficient gamma (NSG) mice were tail vain-injected with rAAV vectors and co-administered with either dimethyl sulfoxide, celastrol, pristimerin or a positive control, bortezomib. The transgene expression in liver was detected and compared over time.

RESULTSWe observed that treatment with pristimerin, at as low as 1 μmol/L concentration, significantly enhanced rAAV2 vector-mediated transgene expression in vitro, and intraperitoneal co-administration with pristimerin at 4 mg/(kg·d) for 3 d dramatically facilitated viral transduction in murine hepatocytes in vivo. The transduction efficiency of the tyrosine-mutant rAAV2 vectors as well as that of rAAV8 vectors carrying oversized transgene cassette was also augmented significantly by pristimerin. The underlying molecular mechanisms by which pristimerin mediated the observed increase in the transduction efficiency of rAAV vectors include both inhibition of proteasomal degradation of the intracellular proteins and enhanced nuclear translocation of the vector genomes.

CONCLUSIONThese studies suggest the potential beneficial use of pristimerin and pristimerin-containing herb extract in future liver-targeted gene therapy with rAAV vectors.

Animals ; Cell Line ; Dependovirus ; genetics ; physiology ; Gene Expression ; drug effects ; Genetic Therapy ; Genetic Vectors ; genetics ; physiology ; Hepatocytes ; metabolism ; virology ; Humans ; Liver ; cytology ; metabolism ; virology ; Mice ; Transgenes ; drug effects ; Triterpenes ; pharmacology

OBJECTIVETo detect p24 antigen of human immunodeficiency virus (HIV)-1 in the liver biopsy specimens of patients with HIV infection.

METHODSLiver biopsy samples from 14 patients with HIV/AIDS (11 man, 3 women; age range 27-52 years; infection time range 8-13 years) were examined by immunohistochemistry prospectively.

RESULTSIntracellular expression of HIV-1 p24 antigen was detected in Kupffer cells, endothelial cells and hepatocytes. There were more HIV-positive liver cells in the patients with severer liver damage than those with milder liver damage (t=2.5189, P=0.0270).

CONCLUSIONThese findings indicate that HIV-1 could replicate in the liver of HIV-infected patients and might be related to the liver cells apoptosis.

Adult ; Female ; HIV Core Protein p24 ; biosynthesis ; HIV Infections ; metabolism ; virology ; HIV-1 ; physiology ; Hepatocytes ; metabolism ; pathology ; Host-Pathogen Interactions ; Humans ; Immunohistochemistry ; Liver ; metabolism ; pathology ; virology ; Male ; Middle Aged

BACKGROUND/AIMS: It is essential to develop an in vitro culture model of primary hepatocytes for the study of hepatocellular function and the pathogenesis of hepatitis C virus (HCV) infection. In this study, we have established the immortalized primary human hepatocyte (IPHH) and performed in vitro culture of HCV derived from human patient. METHODS: Primary human hepatocytes were isolated from surgically resected liver tissue and then were immortalized by transfection with the SV40 large T antigen. The characterization of the IPHH during culture was analyzed by immunocytochemistry, RT-PCR, Western blot, ELISA, and soft agar assay. Next, sera and/or liver tissue homogenates from surgically resected liver tissues of patients with HCV infection were inoculated for the culture of HCV in IPHH. After HCV RNA extraction from IPHH and culture media, positive or negative stranded HCV RNA was examined by specific nest RT-PCR. RESULTS: IPHH expressed liver-associated proteins but did not express alpha-fetoprotein. Also IPHH showed ammonia removal activity. With regard to its malignant potential, colony formation in soft agar assay was not observed. Next, positive and negative stranded HCV RNAs in IPHH infected with patient's sera plus liver tissue homogenates were clearly detected whereas those in IPHH infected with only patient's sera were not detected. CONCLUSIONS: These results demonstrated the phenotypic characteristics of IPHH and the feasibility in vitro culture system of HCV infected human samples. This system might be useful for study of pathogenesis of HCV infection or hepatocyte-based applications.
Antigens, Viral, Tumor/genetics ; Base Sequence ; Carcinogenicity Tests ; Cell Culture Techniques ; Cells, Cultured ; Cells, Immobilized ; Hepacivirus/isolation & purification/*physiology ; Hepatocytes/metabolism/physiology/*virology ; Humans ; Liver Function Tests ; Models, Biological ; RNA Probes ; RNA, Viral/analysis ; Reverse Transcriptase Polymerase Chain Reaction

OBJECTIVEBy studying the possibility of obtaining expression of human hepatitis B virus (HBV) genes and production in normal liver cells from heterologous species like normal primary duck hepatocytes (PDH), to investigate the species-specificity of HBV infection and replication.

METHODSTwo days after transfecting the complete HBV genome into PDH by electroporation (transfected group), HBsAg and HBeAg in the supernatants and lysates of PDH were measured by the IMX system. Meanwhile, replication of HBV in PDH was analyzed by Southern blotting and dot blotting procedures. PDH was electroporated as control.

RESULTSHBsAg in the lysate of transfected group was 9.10 (P/N values, positive?2.1), HBeAg was 1.0 (negative?2.1), both were negative in the supernatants of transfected group. dot blotting revealed that transfected group was strongly positive, whereas the control group was negative. Southern blot analysis of intracellular total DNA indicated that there were relaxed circular (RC), covalently closed circular (CCC) and single-stranded (SS) HBV DNA replicative intermediates in the transfected group, and there was no integrated HBV DNA in the cellular genome. Control groups were negative.

CONCLUSIONSReplication of HBV can occur in hepatocytes from nonmammalian species, which strongly supports the idea that replication of HBV has no critical species-specificity, and yet it depends on the endoenvironment of hepatocyte.

Animals ; Cells, Cultured ; DNA Replication ; physiology ; DNA, Viral ; biosynthesis ; Disease Models, Animal ; Ducks ; Electroporation ; Hepatitis B Surface Antigens ; analysis ; Hepatitis B e Antigens ; analysis ; Hepatitis B virus ; genetics ; physiology ; Hepatocytes ; metabolism ; virology ; Humans ; Species Specificity ; Transfection ; Virus Replication

Hepatitis B virus (HBV) is the prototype of hepatotropic DNA viruses (hepadnaviruses) infecting a wide range of human and non-human hosts. Previous studies with duck hepatitis B virus (DHBV) identified duck carboxypeptidase D (dCPD) as a host specific binding partner for full-length large envelope protein, and p120 as a binding partner for several truncated versions of the large envelope protein. p120 is the P protein of duck glycine decarboxylase (dGLDC) with restricted expression in DHBV infectible tissues. Several lines of evidence suggest the importance of dCPD, and especially p120, in productive DHBV infection, although neither dCPD nor p120 cDNA could confer susceptibility to DHBV infection in any cell line. Recently, sodium taurocholate cotransporting polypeptide (NTCP) has been identified as a binding partner for the N-terminus of HBV large envelope protein. Importantly, knock down and reconstitution experiments unequivocally demonstrated that NTCP is both necessary and sufficient for in vitro infection by HBV and hepatitis delta virus (HDV), an RNA virus using HBV envelope proteins for its transmission. What remains unclear is whether NTCP is the major HBV receptor in vivo. The fact that some HBV patients are homozygous with an NTCP mutation known to abolish its receptor function suggests the existence of NTCP-independent pathways of HBV entry. Also, NTCP very likely mediates just one step of the HBV entry process, with additional co-factors for productive HBV infection still to be discovered. NTCP offers a novel therapeutic target for the control of chronic HBV infection.
Animals ; Carboxypeptidases/genetics/*metabolism ; Gene Products, pol/genetics/metabolism ; Heparan Sulfate Proteoglycans/metabolism ; Hepatitis B virus/*physiology ; Hepatocytes/metabolism/virology ; Organic Anion Transporters, Sodium-Dependent/antagonists & inhibitors/genetics/metabolism ; RNA Interference ; Symporters/antagonists & inhibitors/genetics/metabolism ; Viral Envelope Proteins/metabolism ; Virus Internalization

We recently developed a mouse model of hepatitis B virus (HBV) chronic infection by intravenous (i.v.) injection with rAAV8-1. 3HBV to C57BL/6 mice. To define the responses of different mouse strains after injection with rAAV8-1. 3HBV, we intravenously injected rAAV8-1. 3HBV at doses of 4 x10(9) (Viral genome,vg), 4 x 10(10) vg and 4 x 10(11) vg to C57BL/6 and BALB/c mice,respectively, and determined the levels of serum HBV antigen and antibody by ELISA,serum viral DNA by real-time PCR,and HBcAg expression in liver by immunohistochemical staining. For C57BL/6 mouse strain with injection of rAAV8-1. 3HBV at three doses, 100% of the mice carried HBV for more than 8 months. The levels of serum HBsAg and HBeAg, serum viral DNA and HBcAg-positive hepatocytes increased in a rAAV8-1. 3HBV dose-dependent manner. For C57BL/6 mice injected with rAAV8-1. 3HBV at the dose of 4 x 10(11) vg,over 40% of hepatocytes expressed HBcAg and serum viral DNA reached over 10(5) IU/mL. No HBV antibody was detected in sera of C57BL/6 mice. For BALB/c mice with injection of rAAV8-1. 3HBV at three doses, serum HBeAg, serum viral DNA and HBcAg-positive hepatocytes persisted for more than 8 months, but serum HBsAg declined remarkably at 2 weeks after injection. The levels of serum HBeAg and HBcAg-positive hepatocytes in BALB/c mice increased in a rAAV8-1. 3HBV dose-dependent manner. Injection with rAAV8-1. 3HBV at the dose of 4 x 10(11) vg resulted in over 50% of BALB/c mice hepatocytes expressing HBcAg. Serum anti-HBsAg were detected in BALB/c mice with rAAV8-1. 3HBV injection at the dose of 4 x10 (10) vg. In conclusion, both C57BL/6 and BALB/c strains can be developed to chronic HBV infection mouse models by i. v. injection with rAAV8-1. 3HBV at doses of 4 x10(9) - 4 x 10(11) vg and the levels of HBV replication increase in a rAAV8-1. 3HBV dose-dependent manner. In contrast to C57BL/6 strain, the BALB/c mice carry out humoral immunity to HBsAg, but fail to mediate HBV clearance.
Animals ; Dependovirus ; genetics ; metabolism ; Disease Models, Animal ; Genetic Vectors ; genetics ; metabolism ; Hepatitis B ; immunology ; virology ; Hepatitis B Antibodies ; immunology ; Hepatitis B Surface Antigens ; immunology ; Hepatitis B e Antigens ; immunology ; Hepatitis B virus ; genetics ; immunology ; physiology ; Hepatocytes ; immunology ; virology ; Humans ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Transduction, Genetic ; Virus Replication