Atsushi Naganuma

Characterization of antiviral activity of lactoferrin against hepatitis C virus infection in human cultured cells.

We recently found that bovine lactoferrin (bLF), a milk glycoprotein belonging to the iron transporter family, prevented hepatitis C virus (HCV) infection in human hepatocyte PH5CH8 cells, that are susceptible to HCV infection, and demonstrated that the anti-HCV activity of bLF was due to the interaction of bLF and HCV. In this study we further characterized the anti-HCV activity of bLF and the mechanism by which bLF prevents HCV infection. We found that bLF inhibited viral entry to the cells by interacting directly with HCV immediately after mixing of bLF and HCV inoculum. The anti-HCV activity of bLF was lost by heating at 65 degrees C, and other milk proteins (mucin, beta-lactoglobulin and casein) did not prevent HCV infection, indicating that bLF prevented HCV infection in a rather specific manner. Furthermore, we found that bovine lactoferricin, a basic N-terminal loop of bLF that is an important region for antibacterial activity, did not exhibit any anti-HCV activity, suggesting that some other region is involved in anti-HCV activity. We confirmed that prevention of HCV infection by bLF was a general phenomenon, because bLF inhibited HCV infection with all five inocula examined, and bLF inhibited HCV infection in human MT-2C T-cells, that were susceptible to HCV infection. In addition, infection with hepatitis G virus, which is distantly related to HCV, was prevented also by bLF. In conclusion, lactoferrin is a natural glycoprotein which effectively protects against HCV infection in hepatocytes and lymphocytes by neutralizing the virus.

Activation of the Interferon-Inducible 2′-5′-Oligoadenylate Synthetase Gene by Hepatitis C Virus Core Protein

ABSTRACT The effects of hepatitis C virus (HCV) proteins on several signal transduction pathways in human nonneoplastic hepatocyte PH5CH8 cells were investigated using expression vectors encoding HCV proteins derived from HCV-infected human nonneoplastic cultured T-lymphocyte and hepatocyte cells (MT-2C and PH5CH7), which could support HCV replication. The amino acid sequences of HCV proteins obtained from HCV-infected human cells were identical or very close to the consensus sequences of the proteins derived from the original inoculum used for HCV infection. During the course of the study, we found that HCV core protein specifically activated the 40/46-kDa 2′-5′-oligoadenylate synthetase (2′-5′-OAS) gene promoter in a dose-dependent manner in different human hepatocyte cell lines (PH5CH8, HepG2, and PLC/PRF/5). We also found that the activation by core protein was further enhanced in the cells treated with alpha interferon. The expression of E1 or E2 envelope protein or nonstructural NS5A protein did not activate the 2′-5′-OAS gene promoter. We demonstrated that the activation by core protein in the hepatocyte cells was suppressed by antisense RNA complementary to core-encoding RNA. Deletion mutant analysis of core protein and deletion analysis of the 2′-5′-OAS gene promoter have been performed. Finally, we demonstrated that the activation of the 2′-5′-OAS gene occurred at the transcriptional level and furthermore demonstrated that the endogenous 2′-5′-OAS gene was also activated by core protein. This is the first report to show that a viral protein activated the 2′-5′-OAS gene.

Preventive effects of vitamin K on recurrent disease in patients with hepatocellular carcinoma arising from hepatitis C viral infection

Background:  Despite the progression of therapeutic approaches, a high frequency of recurrence is what determines the long‐term prognosis of patients with hepatocellular carcinoma (HCC). In this study, the chemopreventive effects of vitamin K2 on the recurrence and survival of patients with HCC after curative therapy were evaluated.

Promotion of Microsatellite Instability by Hepatitis C Virus Core Protein in Human Non-neoplastic Hepatocyte Cells

Hepatitis C virus proteins exert an effect on a variety of cellular functions, including gene expression, signal transduction, and apoptosis, and because they possess oncogenic potentials, they have also been suggested to play an important role in hepatocarcinogenesis. Although the mechanisms of hepatocarcinogenesis remain poorly understood, we hypothesized that the disease may arise because of a disturbance of the DNA repair system by hepatitis C virus proteins. To test this hypothesis, we developed a reproducible microsatellite instability assay system for mismatch-repair using human-cultured cells transducted with pCXpur retrovirus expression vector, in which the puromycin resistance gene was rendered out-of-frame by insertion of a (CA)17 dinucleotide repeat tract immediately following the ATG start codon. Using several human cancer cell lines known to be replication error positive or negative, we demonstrated that this assay system was useful for monitoring the propensity for mismatch-repair in the cells. This assay system was applicable to non-neoplastic human PH5CH8 hepatocytes, which could support hepatitis C virus replication. Using PH5CH8 cells, in which hepatitis C virus proteins were stably expressed by the retrovirus-mediated gene transfer, we found that the core protein promoted microsatellite instability in PH5CH8 cells. Interestingly, such promotion by the core protein only occurred in cells having the core protein belonging to genotype 1b or 2a and did not occur in cells having the core protein belonging to genotype 1a, 2b, or 3a. This is the first report to demonstrate that the core protein may disturb the DNA repair system.

Circulating microRNA Profiles in Patients with Type-1 Autoimmune Hepatitis

Recent studies have demonstrated that micro (mi)RNA molecules can be detected in the circulation and can serve as potential biomarkers of various diseases. This study used microarray analysis to identify aberrantly expressed circulating miRNAs in patients with type 1 autoimmune hepatitis (AIH) compared with healthy controls. Patients with well-documented and untreated AIH were selected from the National Hospital Organization (NHO)-AIH-liver-network database. They underwent blood sampling and liver biopsy with inflammation grading and fibrosis staging before receiving treatment. To further confirm the microarray data, circulating expression levels of miR-21 and miR-122 were quantified by real-time quantitative polymerase chain reaction in 46 AIH patients, 40 patients with chronic hepatitis C (CHC), and 13 healthy controls. Consistent with the microarray data, serum levels of miR-21 were significantly elevated in AIH patients compared with CHC patients and healthy controls. miR-21 and miR-122 serum levels correlated with alanine aminotransferase levels. Circulating levels of miR-21 and miR-122 were significantly reduced in AIH patients with liver cirrhosis, and were inversely correlated with increased stages of fibrosis. By contrast, levels of circulating miR-21 showed a significant correlation with the histological grades of inflammation in AIH. We postulate that aberrantly expressed serum miRNAs are potential biomarkers of AIH and could be implicated in AIH pathogenesis. Alternations of miR-21 and miR-122 serum levels could reflect their putative roles in the mediation of inflammatory processes in AIH.

Association of STAT4 Polymorphisms with Susceptibility to Type-1 Autoimmune Hepatitis in the Japanese Population

Background/Aims Recent studies demonstrated an association of STAT4 polymorphisms with autoimmune diseases including systemic lupus erythematosus and rheumatoid arthritis, indicating multiple autoimmune diseases share common susceptibility genes. We therefore investigated the influence of STAT4 polymorphisms on the susceptibility and phenotype of type-1 autoimmune hepatitis in a Japanese National Hospital Organization (NHO) AIH multicenter cohort study. Methodology/Principal Findings Genomic DNA from 460 individuals of Japanese origin including 230 patients with type-1 autoimmune hepatitis and 230 healthy controls was analyzed for two single nucleotide polymorphisms in the STAT4 gene (rs7574865, rs7582694). The STAT4 rs7574865T allele conferred risk for type-1 autoimmune hepatitis (OR = 1.61, 95% CI = 1.23–2.11; P = 0.001), and patients without accompanying autoimmune diseases exhibited an association with the rs7574865T allele (OR = 1.50, 95%CI = 1.13–1.99; P = 0.005). Detailed genotype-phenotype analysis of type-1 autoimmune hepatitis patients with (n = 44) or without liver cirrhosis (n = 186) demonstrated that rs7574865 was not associated with the development of liver cirrhosis and phenotype (biochemical data and the presence of auto-antibodies). Conclusions/Significance This is the first study to show a positive association between a STAT4 polymorphism and type-1 autoimmune hepatitis, suggesting that autoimmune hepatitis shares a gene commonly associated with risk for other autoimmune diseases.

Hepatitis C virus NS5B RNA replicase specifically binds ribosomes

Hepatitis C virus (HCV) non‐structural protein 5B (NS5B) is an RNA replicase. We expressed full‐length NS5B (591 amino acid residues) in Escherichia coli as a fusion protein with maltose binding protein (MBP‐NS5B). MBP‐NS5B was recovered in the soluble fraction after centrifugation at 40,000 × g and affinity‐purified with amylose resin. The purified MBP‐NS5B had a high‐level of poly (A), oligo (U)‐dependent UMP incorporation with a Km of 2 μm for UTP. Surprisingly, the enzymatically active MBP‐NS5B was sedimented by ultracentrifugation at 160,000 × g. The pellet contained 16S and 23S ribosomal RNAs, suggesting that ribosomes were associated with MBP‐NS5B. Ribosomes and MBP‐NS5B were subsequently co‐purified on amylose resin. Deletion study revealed that either the N‐terminal (amino acid residues 1 107) or the C‐terminal (amino acid residues 498–591) region of NS5B were sufficient for this association with ribosomes. We further found that NS5B also bound with human ribosomes. Our results implicate a novel mechanism of coupling between replication and translation of the viral genome in the life cycle of HCV.

Genome-wide association studies identify PRKCB as a novel genetic susceptibility locus for primary biliary cholangitis in the Japanese population

&NA; A previous genome‐wide association study (GWAS) performed in 963 Japanese individuals (487 primary biliary cholangitis [PBC] cases and 476 healthy controls) identified TNFSF15 (rs4979462) and POU2AF1 (rs4938534) as strong susceptibility loci for PBC. In this study, we performed GWAS in additional 1,923 Japanese individuals (894 PBC cases and 1,029 healthy controls), and combined the results with the previous data. This GWAS, together with a subsequent replication study in an independent set of 7,024 Japanese individuals (512 PBC cases and 6,512 healthy controls), identified PRKCB (rs7404928) as a novel susceptibility locus for PBC (odds ratio [OR] = 1.26, P = 4.13 × 10‐9). Furthermore, a primary functional variant of PRKCB (rs35015313) was identified by genotype imputation using a phased panel of 1,070 Japanese individuals from a prospective, general population cohort study and subsequent in vitro functional analyses. These results may lead to improved understanding of the disease pathways involved in PBC, forming a basis for prevention of PBC and development of novel therapeutics.

Efficacy and safety of glecaprevir/pibrentasvir in Japanese patients with chronic genotype 2 hepatitis C virus infection

Glecaprevir (nonstructural protein 3/4A protease inhibitor) and pibrentasvir (nonstructural protein 5A inhibitor) (G/P), a coformulated once‐daily, all oral, ribavirin (RBV)‐free, direct‐acting antiviral regimen, was evaluated for safety and efficacy in hepatitis C virus genotype 2 (GT2)–infected Japanese patients, including those with compensated cirrhosis. CERTAIN‐2 is a phase 3, open‐label, multicenter study assessing the safety and efficacy of G/P (300/120 mg) once daily in treatment‐naive and interferon ± RBV treatment–experienced Japanese patients without cirrhosis but with GT2 infection. Patients were randomized 2:1 to receive 8 weeks of G/P (arm A) or 12 weeks of sofosbuvir (400 mg once daily) + RBV (600‐1000 mg weight‐based, twice daily) (arm B). The primary endpoint was noninferiority of G/P compared to sofosbuvir + RBV by assessing sustained virologic response at posttreatment week 12 (SVR12) among patients in the intent‐to‐treat population. SVR12 was also assessed in treatment‐naive and interferon ± RBV treatment‐experienced patients with GT2 infection and compensated cirrhosis who received G/P for 12 weeks in the CERTAIN‐1 study. A total of 136 patients were enrolled in CERTAIN‐2. SVR12 was achieved by 88/90 (97.8%) patients in arm A and 43/46 (93.5%) patients in arm B. No patient in arm A experienced virologic failure, while 2 did in arm B. The primary endpoint was achieved. In CERTAIN‐1, 100% (18/18) of GT2‐infected patients with compensated cirrhosis achieved SVR12. Treatment‐emergent serious adverse events were experienced by 2 patients without cirrhosis in each arm and no patient with cirrhosis. Conclusion: The results demonstrate high efficacy and favorable tolerability of G/P in GT2‐infected Japanese patients. (Hepatology 2018;67:505‐513).

HLA-DRB1 and DQB1 alleles in Japanese type 1 autoimmune hepatitis: The predisposing role of the DR4/DR8 heterozygous genotype

Objective Autoimmune hepatitis (AIH) is a chronic progressive liver disease. AIH is composed predominantly of type 1 in Japanese populations. The genetic and environmental factors are associated with the pathogenesis of AIH. HLA-DRB1*03:01 and *04:01 are associated with type 1 AIH in European and *04:05 in Japanese populations. Here, we conducted an HLA association study in order to find HLA alleles or haplotypes predisposing or protective for Japanese AIH. Methods HLA-DRB1 and DQB1 genotyping of 360 type 1 AIH patients and 1026 healthy controls was performed. Results The predisposing association of DRB1*04:01 (P = 0.0006, corrected P [Pc] = 0.0193, odds ratio [OR] 2.97, 95% confidence interval [CI] 1.62–5.43), DRB1*04:05 (P = 1.89×10−21, Pc = 5.86×10−20, OR 3.41, 95% CI 2.65–4.38), and DQB1*04:01 (P = 4.66×10−18, Pc = 6.99×10−17, OR 3.89, 95% CI 2.84–5.33) and the protective association of DRB1*13:02 (P = 0.0003, Pc = 0.0080, OR 0.48, 95% CI 0.32–0.72) with Japanese type 1 AIH were observed. An association of the DR4/DR8 heterozygous genotype with Japanese AIH was identified for the first time (P = 3.12×10−9, OR 3.52, 95% CI 2.34–5.29). Susceptible diplotypes were DRB1*04:05-DQB1*04:01/DRB1*08:02-DQB1*03:02 (P = 0.0004, OR 24.77, 95% CI 1.45–424.31) and DRB1*04:05-DQB1*04:01/DRB1*08:03-DQB1*06:01 (P = 1.18×10−6, OR 10.64, 95% CI 3.19–35.46). Serum levels of Immunoglobulin G and Immunoglobulin M, International Autoimmune Hepatitis Group score, positive rate of anti-smooth muscle antibodies, and the rate of definite AIH were higher in AIH patients with DRB1*04:05 than without. Conclusions The important roles of specific combinations of DRB1 and DQB1 alleles or haplotypes in the pathogenesis of type 1 AIH were suggested. The association of DR4/DR8 heterozygous genotype suggested the pathologic importance of trans-complementing DQα-β heterodimer molecules encoded by DQA1 allele of one haplotype and the DQB1 allele of the other haplotype, as it was proposed in the HLA association studies of Type 1 diabetes.