Takaji Wakita

A pilot study of ribavirin and interferon beta for the treatment of chronic hepatitis C

BACKGROUNDnChronic hepatitis C is a common and often progressive liver disease for which interferon alfa therapy widely spreads, but the beneficial response is frequently transient. Ribavirin is a nucleoside analog with a broad spectrum of antiviral action, and we investigated the efficacy of it in patients with chronic active hepatitis C.nnnMETHODSnWe conducted a pilot study of oral ribavirin in patients with chronic active hepatitis C. Twenty-seven patients with hepatitis C virus RNA were randomly assigned to receive either 0.8-1.0 g of ribavirin daily or 3 MU of interferon beta three times weekly or combination of the two for 24 weeks.nnnRESULTSnRibavirin was tolerated well, and all completed the treatment schedule. Ribavirin decreased aminotransferase levels in all instances, and the mean value at termination decreased to half of the baseline level (P < 0.01), but the enzyme level increased after cessation of therapy in most cases. Ribavirin suppressed amounts of hepatitis C virus RNA in 4 of 9 patients, and 1 became negative during follow-up. Interferon alone (P < 0.05) or with ribavirin (P < 0.01) significantly decreased the viral population, resulting in sustained loss of viremia with normal enzyme levels in 2 of 9 and 3 of 9 patients, respectively, in each therapy during follow-up.nnnCONCLUSIONSnThese results indicate that ribavirin has a beneficial effect in some patients with chronic hepatitis C, although the antiviral effect is less than interferon beta. Large-scale trials are needed to determine whether the combination of interferon and ribavirin is of more benefit than interferon alone.

Differential cellular and humoral immune responses to HCV core and HBV envelope proteins after genetic immunizations using chimeric constructs

Development of a broad based cellular and humoral immune response to hepatitis C virus (HCV) structural proteins may be important for eradication of viral infection. In previous studies in mice we demonstrated that facilitated DNA-based immunization with an HCV core DNA-expression construct stimulated the generation of weak cytotoxic T lymphocyte (CTL), helper T cell (Th), and humoral immune responses against HCV core related epitopes. To enhance the immunogenicity of this non-secreted viral structural protein at both the B- and T-cell level, several chimeric HBV-HCV constructs were prepared which were designed to express and secrete HCV core protein along with various regions of the hepatitis B envelope protein. No secretion of the chimeric proteins into the culture supernatant was detected using sensitive radioimmunoassays. However, such chimeric proteins were capable of generating CD4+ inflammatory T cell and CD8+ CTL activity against both HBV and HCV components of the fusion proteins. It was determined that the proliferative activity of T cells as well as the humoral immune responses to HCV core protein were substantially enhanced by some chimeric fusion proteins as compared to the HCV core protein alone. The strength of the immune responses appeared directly related to the level of Th1 cytokines produced by CD4+ T cells obtained from immunized animals. Further characterization of the immune responses stimulated by these DNA constructs studied helped to define some of the most immunogenic regions of the chimeric proteins that they encode.

Characterization of three novel monoclonal antibodies against hepatitis C virus core protein.

Three novel monoclonal antibodies (MAbs) were established against a recombinant hepatitis C virus (HCV) core protein derived from cloned genotype 1b HCV cDNA. MAbs C7‐50 and C8‐59 recognize a conserved linear epitope represented by amino acid residues 21 to 40 of the nucleocapsid protein. MAb C8‐48 is directed against a strain‐specific conformational epitope located within the first 82 amino acids. A sensitive two‐site MAb‐based immunoradiometric assay was established using antibodies directed against distinct epitopes on the nucleocapsid protein. Processed 21 kDa core protein was detected by immunoblotting in human hepatocellular carcinoma cell lines and primary adult rat hepatocytes transfected with a cytomegalovirus promoter‐driven expression construct. Immunofluorescence microscopy studies revealed a granular and vesicular cytoplasmic staining pattern. MAb C7‐50 was used successfully to detect HCV core antigen in chronically infected chimpanzee liver tissue. These MAbs represent important reagents for the study of HCV biology and for the development of immunodiagnostic assays.

Comparison between cytomegalovirus promoter and elongation factor-1α promoter-driven constructs in the establishment of cell lines expressing hepatitis C virus core protein

The establishment of stable cell lines expressing the hepatitis C virus (HCV) core protein may be important for studies of HCV pathogenesis. Human and mouse cell lines were generated expressing the HCV core protein using expression vectors driven by either the cytomegalovirus (CMV) or elongation factor-1 alpha (EF-1 alpha) promoters. Following transient transfection, HCV core protein was expressed in all cell lines. However, stable human hepatocellular carcinoma (HCC) and murine myeloma cell lines expressing the HCV core protein were only established using constructs driven by the EF-1 alpha promoter. In contrast, stable expression of the hepatitis B virus (HBV) middle envelope protein (MHBs) was obtained successfully in these cell lines using an expression vector driven by the CMV promoter. Inhibitory activity of the first 69 amino acids of the HCV core protein on the CMV promoter was found by using chimeric MHBs/HCV core protein constructs. Growth of cloned cell lines expressing the HCV core protein was slower than that of nonexpressing cell lines. However, morphological changes and cell death were not observed in the stable cell lines expressing HCV core protein. These results indicate that the HCV core protein was not directly cytotoxic to HCC and myeloma cell lines but that specific promoter elements are required to establish stable expression of the nucleocapsid structural protein.

Effects of TJ-9 Sho-saiko-to (kampo medicine) on interferon gamma and antibody production specific for hepatitis B virus antigen in patients with type B chronic hepatitis

To examine whether Sho-saiko-to (kampo medicine) could modulate the immune response of immunocompetent cells to hepatitis B virus (HBV)-associated antigens, we investigated in vitro interferon gamma (IFN-gamma) and antibody (antibody to HB core and e antigens; anti-HBc and anti-HBe) production by peripheral blood mononuclear cells (PBMC) from eight patients with chronic active hepatitis (CAH) (four with HBeAg and four with anti-HBe) in the presence of recombinant HBcAg and purified HBeAg. IFN-gamma and antibody production were measured using ELISA and RIA, respectively. PBMC from both HBeAg and anti-HBe positive patients generated significantly increased IFN-gamma and antibody (anti-HBc and anti-HBe) production in the culture containing Sho-saiko-to (TJ-9) in a dose-dependent manner in comparison with those of medium alone culture. Similarly, when various concentrations of TJ-9 were added to the HBV antigen-stimulated cultures, TJ-9 was found to enhance both IFN-gamma and antibody production dose-dependently. These results indicate that TJ-9 is able to modulate both cellular and humoral immune responses specific for HBV-associated antigens. These findings also may account for, at least in part, the efficacy of TJ-9 treatment for type B chronic hepatitis.

Antiviral effects of antisense RNA on hepatitis C virus RNA translation and expression

We developed approaches using antisense RNA to inhibit hepatitis C virus (HCV) RNA translation and HCV core protein expression. An HCV genotype 1b cDNA comprising nt 1‐1321 or a fusion construct consisting of HCV (nt 1‐584) and luciferase cDNAs were inserted downstream of T7 and CMV promoter sequences and used to generate HCV RNA target molecules. Such constructs will produce HCV core or HCV core–luciferase fusion proteins in vitro or within transfected cells. Seven different antisense RNA constructs were designed to target the highly conserved 5′ region of HCV RNA at nt positions 1‐402. For in vitro experiments, synthesized HCV RNA target sequences and antisense RNAs were mixed at various molar ratios and subsequently translated in a rabbit reticulocyte lysate system. In cell culture studies, the HCV core–luciferase fusion cDNA was co‐transfected with antisense RNA‐producing constructs into human hepatocellular carcinoma (HCC) cells. Luciferase activity in cell lysates was measured to determine quantitatively antiviral effects within the cell. It was found that translation of HCV RNAs was efficiently inhibited by antisense RNA in vitro. The specificity of this inhibition was confirmed using control target RNA sequences or nonrelevant antisense RNA constructs. Co‐transfection studies demonstrated that antisense RNA inhibited HCV core–luciferase fusion protein expression by 41–57% in HuH‐7 HCC cells. These studies indicate that antisense RNA will find viral target RNA sequences in HuH‐7 cells and inhibit HCV RNA translation. More important, these studies have defined critical viral RNA target sequences susceptible to antisense inhibitory effects within the cell. J. Med. Virol. 57:217–222, 1999.

Interleukin 6 production by peripheral blood mononuclear cells in patients with chronic hepatitis B virus infection and primary biliary cirrhosis

SummaryIL-6 production by peripheral blood mononuclear cells (PBMC) was studied in patients with chronic hepatitis B virus (HBV) infection and primary biliary cirrhosis (PBC) using the ELISA method. Spontaneous production of IL-6 was significantly increased in patients with HBeAg+ chronic hepatitis (CH). The cultures stimulated with lipopolysaccharide and lectin-free interleukin-2 (IL-2) showed enhanced IL-6 production both in controls and all patient groups compared with culture without any stimulation. IL-6 production in response to IL-2 was higher in patients with HBeAg+ CH and PBC than in controls. In PBMC with increased IL-6 production, monocyte function was increased in patients with HBeAg+ CH and PBC, while B cells from PBC showed elevated response to Staphylococcus aureus Cowan 1. IL-6 production in the presence of HBeAg was greater in anti-HBe+ patients than in HBeAg+ ones. These results suggest that IL-6 response is involved in the immune response in patients with chronic liver disease.

Serial analysis of hepatitis B virus core nucleotide sequence of patients with acute exacerbation during chronic infection

Recent studies suggest that hepatitis B virus (HBV) core region could be an immunological target and that amino acid (aa) substitutions are mostly restricted to a small segment located in the middle of the core region. We sequenced the middle portion of HBV core gene during the course of acute exacerbation of chronic hepatitis B, and compared aa variations between the region including ideal HLA‐A2 binding motifs and the nonbinding region. Five HBeAg+ chronic hepatitis patients with subtype adr (three with HLA‐A2 and two without HLA‐A2) were selected and using polymerase chain reaction (PCR) and cloning system, the central part of core region (nt 2063 to 2365, 303 bp) was sequenced in sera from each patient at three time points; before, at the peak of, and after exacerbation of hepatitis. The second set of sera showed higher aa substitution rates in five and in three out of five patients compared with those of the first and third sera, respectively. No significant difference was found in the aa substitution rates for the region with ideal HLA‐A2 binding motifs between patients with and without HLA‐A2. In asymptomatic HBV carriers with persistently normal aminotransferase values, alterations of the aa sequence were not observed within the same time frame. The results suggest that aa substitutions often occur at some particular positions in the middle of HBV core region during acute exacerbation of the disease under possible host immune pressures. Furthermore, unidentified epitopes appear to exist in the central part of HBV core region and HLA‐unrestricted lymphocytes may play a role in the immune response of chronic HBV carriers.

Production of tumor necrosis factor, interleukin 1, and interferon-γ by peripheral blood mononuclear cells from patients with primary biliary cirrhosis

Since patients with primary biliary cirrhosis (PBC) have evidence of abnormal function of the immune system, we evaluated production of various cytokines by peripheral blood mononuclear cells (PBMCs) and monocytes from patients with this disease, using an enzyme-linked immunosorbent assay. The mean amounts of production of tumor necrosis factor alpha(TNF alpha), interleukin 1 beta (IL1 beta), and interferon-gamma (IFN-gamma) by PBMCs from patients with PBC tended to be increased in cultures in the presence of stimulating agents in comparison with controls, but there was no significant difference because of a wide scatter of results. Monocytes from PBC patients also tended to produce higher amounts of TNF alpha and IL1 beta than control monocytes did, although the percentage of monocytes in PBMCs was similar in PBC and controls. A significant correlation was found between TNF alpha production and IL1 beta production in PBC patients. The number of TNF alpha or IFN-gamma positive infiltrating mononuclear cells detected by immunohistochemical staining in liver biopsy sections correlated with the production of these cytokines by PBMCs in vitro. However, cytokine production did not correlate with serum biochemical or hepatic histologic findings, except for serum alkaline phosphatase values. In patients with type B chronic active hepatitis, IL1 beta and IFN-gamma production was similar to controls, while TNF alpha production tended to be enhanced. Thus the cytokines studied here may play some role in the pathogenesis of PBC.

Cellular Immune Responses of Peripheral Blood Mononuclear Cells to HBV Antigens during Chronic and Acute HBV Infection

Patients with acute self-limited and chronic HBV infection were studied to determine their in vitro cellular immune response to HBV antigens. In interferon-gamma production cultures which were evaluated as an indicator of cellular immune response, peripheral blood mononuclear cells from patients with HBeAg-positive chronic hepatitis showed elevated response to HBcAg, while those from HBeAg-positive asymptomatic carriers revealed no response to either HBcAg or HBeAg. HBeAg-stimulated interferon-gamma production was higher in anti-HBe-positive chronic hepatitis and asymptomatic carriers than that in HBeAg-positive patients. Interferon-gamma production against HBcAg was shown to be HLA class II restricted by blocking assay using monoclonal antibodies. HBsAg with or without pre-S2 did not amplify interferon-gamma production of patients with chronic hepatitis. In acute hepatitis B, both envelope and nucleocapsid antigens induced greater interferon-gamma production than in chronic HBV carriers. These results indicate that the patients with acute hepatitis responded more to HBV antigens compared with chronic HBV carriers. Furthermore, enhanced cellular immune responses, particularly to HBeAg, were observed in anti-HBe-positive patients compared to HBeAg-positive patients during chronic HBV infection, suggesting that the poor response to HBeAg in HBeAg-positive patients may account for the failure to clear HBV.