Enhanced nuclear factor-kappa B-associated Wnt-1 expression in hepatitis B- and C-related hepatocarcinogenesis: identification by functional proteomics

Summary Chronic infections with hepatitis B and C viruses (HBV and HCV) are etiologically linked to hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC). Both viruses may induce activation of nuclear factor-kappa B (NF-κB) in hepatocytes that plays a crucial role in the regulation of cell growth and apoptosis. Functional proteomics analysis of proteins associated with NF-κB signaling complexes in both viruses-related HCC tumor and non-tumor tissues may disclose possible common mechanisms in hepatocarcinogenesis. By functional proteomics, we analyzed proteins associated with NF-κB-signaling complexes in four-paired human HCC tumor and non-tumor tissues from HBV- and HCV-infected patients, respectively, and in one-paired tissue with dual viral infection. The quantity of NF-κB-associated proteins was semi-quantitatively measured by protein spot intensity on the gels of two-dimensional polyacrylamide gel electrophoresis. The results showed that overexpression of NF-κB-associated Wnt-1 protein in tumor part was detected in the␣majority of HBV- and HCV-infected HCC samples. These data suggest that enhanced expression of NF-κB-associated Wnt-1 protein might be a mechanism of hepatocarcinogenesis common to HBV- and HCV-infected patients. NF-κB signaling pathway and Wnt-1 protein could be potential targets for designing highly effective therapeutic agents in treating HCC and for chemoprevention of hepatocarcinogenesis.     

Effects of lamivudine on the hepatitis B virus specific CD8+ cytotoxic T lymphocyte responses via peptide-MHC tetrameric complexes assay

Lamivudine, an oral nucleoside analogue, inhibitshepatitis B virus (HBV) replication. It has been shown tobe able to restore T cell responsiveness and to induce atype 1 T helper cell (Th 1) immunity in chronic HBVpatients. To further examine the effects of lamivudineon cytotoxic T lmphocyte (CTL) responses, two HBVantigenic peptide-HLA-A2 tetrameric complexes containingpeptides derived from HBV core protein (residues 18-27;FLPSDFFPSV) and polymerase (residue 551-559; YMDDVVLGA)were constructed. These two tetramers were used toserially determine the frequency of HBV antigen-specificCD8⁺ T cells before and during the treatment oflamivudine. The specificity of these tetramers wasconfirmed by (a) nonstaining of CD8⁺ T cells fromHLA-A2-negative HBV patients, (b) having variablefrequency data in the different teteramer measurement,and (c) showing peptide-specific CTL activity in thesorted tetramer-stanining CD8⁺T cells. Lowfrequency of HBV-specific CTLs was measured for bothtetramers before lamivudine treatment. However, thenumber of CD8⁺ T cells specific for HBV core 18-27increased significantly during lamivudine treatment. Incontrast, relatively lower frequency of HBV pol 551-559specific CD8⁺ T cells was persistently measuredafter lamivudine treatment. These results indicated thatthe lamivudine treatment could enhance HBV specific CTLresponses.     

HBcAg-specific CD4+CD25+regulatory T cells modulate immune tolerance and acute exacerbation on the natural history of chronic hepatitis B virus infection

Acute exacerbations (AEs) of chronic hepatitis B (CH-B) are accompanied by increased T cell responses to hepatitis B core and e antigens (HBcAg/HBeAg). Why patients are immunotolerant (IT) to the virus and why AEs occur spontaneously on the immunoactive phase remain unclear. The role of HBcAg-specific CD4(+)CD25(+) regulatory T (T(reg)) cells in AE and IT phases was investigated in this study. The SYFPEITHI scoring system was employed to predict MHC class II-restricted epitope peptides on HBcAg overlapping with HBeAg that were used for T(reg)-cell cloning and for the construction of MHC class II tetramers to measure T(reg) cell frequencies (T(reg) f). The results showed that HBcAg-specific T(reg) f declined during AE accompanied by increased HBcAg peptide-specific cytotoxic T lymphocyte frequencies. Predominant Foxp3-expressing T(reg) cell clones were generated from patients on the immune tolerance phase, while the majority of Th1 clones were obtained from patients on the immunoactive phase. T(reg) cells from liver and peripheral blood of CH-B patients express CD152 and PD1 antigens that exhibit suppression on PBMCs proliferation to HBcAg. These data suggest that HBcAg peptide-specific T(reg) cells modulate the IT phase, and that their decline may account for the spontaneous AEs on the natural history of chronic hepatitis B virus infection.     

Anti-sense morpholino oligonucleotide assay shows critical involvement for NF-κB activation in the production of Wnt-1 protein by HepG2 cells: oncology implications

The link of proto-oncogenic protein Wnt-1 production with NF-κB activation has been functionally demonstrated in PC12 cells, a rat pheochromocytoma cell line of neural crest lineage, while it is not yet verified in human cells. The link can be indirectly supported in our previous report that functional proteomics identifies enhanced expression of NF-κB-associated Wnt-1 production in human hepatocellular carcinoma tissues. This study aimed to further validate this link in human cells using anti-sense strategy. The effects of sequence-specific anti-sense morpholino oligonucleotides (ONs) targeting against pre-mRNA sequences of human p50 and p65 subunits of NF-κB as well as Wnt-1 genes were investigated. It revealed that all the three morpholino ONs inhibited NF-κB activation in human hepatoblastoma cell line HepG2 cells along with decreased Wnt-1 production. Chromatin immunoprecipitation assay ascertained the direct binding of NF-κB-p50 to the Wnt-1 promoter. Additionally, anti-P50 and anti-P65 morpholino ONs also repressed the phosphorylation of Iκ Bα which temporarily correlated with the inhibition of NF-κB activation accompanied by decreased Wnt-1 production by HepG2 cells. In summary, NF-κB activation is critically involved in the production of Wnt-1 by HepG2 cells. These results may have important oncology implications in treating patients with NF-κB-associated Wnt-1-producing cancers. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Effects of lamivudine on the hepatitis B virus specific CD8+ cytotoxic T lymphocyte responses via peptide-MHC tetrameric complexes assay

Summary Lamivudine, an oral nucleoside analogue, inhibits hepatitis B virus (HBV) replication. It has been shown to be able to restore T cell responsiveness and to induce a type 1 T helper cell (Th 1) immunity in chronic HBV patients. To further examine the effects of lamivudine on cytotoxic T Imphocyte (CTL), responses, two HBV antigenic peptide-HLA-A2 tetrameric complexes containing peptides derived from HBV core protein (residues 18–27; FLPSDFFPSV) and polymerase (residue 551–559; YMDDVVLGA) were constructed. These two tetramers were used to serially determine the frequency of HBV antigen-specific CD8⁺ T cells before and during the treatment of lamivudine. The specificity of these tetramers was confirmed by (a) nonstaining of CD8⁺ T cells from HLA-A2-negative HBV patients, (b) having variable frequency data in the different teteramer measurement, and (c) showing peptide-specific CTL activity in the sorted tetramer-stanining CD8⁺T cells. Low frequency of HBV-specific CTLs was measured for both tetramers before lamivudine treatment. However, the number of CD8⁺ T cells specific for HBV core 18–27 increased significantly during lamivudine treatment. In contrast, relatively lower frequency of HBV pol 551–559 specific CD8⁺T cells was persistently measured after lamivudine treatment. These results indicated that the lamivudine treatment could enhance HBV specific CTL responses.     

Activation of Th1 immunity is a common immune mechanism for the successful treatment of hepatitis B and C: tetramer assay and therapeutic implications

Both chronic hepatitis B and C virus (HBV and HCV) infections respond ineffectively to current antiviral therapies. Recent studies have suggested that treatment outcomes may depend on the development of type 1 T helper (Th1) and Th2 cell responses. Specifically, activation of Th1 immunity may play a major role in successfully treating hepatitis B and C. This model was revisited herein by evaluating immune responses in 36 HBV and 40 HCV patients with or without treatment, in an attempt to find a common immune mechanism for successful treatment. The immune responses in all examined cases were studied by peripheral blood mononuclear cell (PBMC) proliferation and cytokine responses to viral antigens, cytotoxic T lymphocyte (CTL) responses, enzyme-linked immunospot (ELISPOT) assay, and tetramer staining of virus-specific CD8+ T cells. The overall results revealed that all responders among both HBV- and HCV-infected cases displayed significantly higher PBMC proliferation to viral antigens with a predominant Th1 cytokine profile. Furthermore, the Th1-dominant responses were associated with significant enhancement of CTL activities and were correlated with ELISPOT data, while non-responders responded more weakly. During therapy, the numbers of tetramer-staining, virus-specific CD8+ T cells showed greater increases in responders than in non-responders (p = 0.001). The frequencies determined by the tetramer assay were approximately 200-fold higher than data estimated by limiting-dilution analysis. In conclusion, activation of Th1 immunity accompanied by enhancement of CTL activity during therapy is a common immune mechanism for successfully treating hepatitis B and C, and therefore may have important therapeutic implications.     

Characterization of T cell clones specific to a determinant of hepatitis B virus core and e antigens in chronic type B hepatitis: Implication for a T cell mechanism of HBV immunopathogenesis

T cell clones specific for hepatitis B core (HBcAg) and e (HBeAg) antigens of hepatitis B virus (HBV) were generated from liver infiltrates of HBeAg-positive patients. Analyzed with a panel of overlapping synthetic peptides spanning the complete sequences of HBcAg and HBeAg, eight clones responded specifically to the e2 peptide (PAYRPPNAPIL; amino acid residues 130–140 of HBcAg and HBeAg), which was doubly restricted by class I and II molecules. A preferential usage of the T cell receptor (TCR) chain variable (V) gene was found: V12.1 for five HLA-Cw9(3)-restricted cytotoxic T lymphocyte (CTL) clones, and V7.1 for three other HLA-DRw52-restricted type 1 helper T cell (Th1) clones. Although heterogeneous in the usage of TCR chain joining region (J) segments, their junctional-region sequences revealed conserved hydrophilic serine residues in seven of the eight e2-specific T cell clones. Single alanine substitution of the centrally located and the only hydrophilic asparagine residue of e2 peptide abrogated T cell responsiveness. The nonstimulatory e2 analogue could competitively inhibit e2-specific responses. These results demonstrate that both CTL and Th1 clones recognizing a determinant of HBcAg and HBeAg are present in the liver of chronic hepatitis B patients. The preferential V gene usage and the expression of conserved residues in junctional-region sequences of TCR chains by viral-peptide-specific, intrahepatic T cells may provide a T cell mechanism of HBV immunopathogenesis.