Ryoko Yada

Expression profile of lipid metabolism‐associated genes in hepatitis C virus‐infected human liver

Aim:  Recent studies have shown that lipid metabolic pathways are required for the entry, replication and secretion of hepatitis C virus (HCV). Although little is known about the life cycle of HCV in humans, the activation of cholesterol and fatty acid biosynthesis may be critical for HCV proliferation.

Expression profiles of genes associated with viral entry in HCV‐infected human liver

Recent studies have demonstrated that several cellular factors are involved in entry of hepatitis C virus (HCV) into host cells. Detailed gene expression profiles of these factors in HCV‐infected livers have not been reported for humans. Transcriptional levels of LDL receptor (LDLR), CD81, scavenger receptor class B type I (SR‐BI), claudin‐1, and occludin genes in liver samples from patients with chronic hepatitis C were investigated. Serum levels of LDL‐cholesterol (LDL‐C) and HCV core antigen were also evaluated, and expression of claudin‐1 and occludin were immunohistochemically analyzed. Compared with normal liver, transcription of LDLR and claudin‐1 genes was significantly suppressed (P < 0.0001) and occludin transcription was significantly up‐regulated in HCV‐infected livers (P < 0.0001). Significant positive correlations were found for LDLR versus occludin, LDLR versus claudin‐1, occludin versus claudin‐1, and CD81 versus SR‐BI in HCV‐infected (P = 0.0012, P < 0.0001, P = 0.0004, and P < 0.0001, respectively) and normal livers (P < 0.0001, P = 0.0051, P < 0.0001, and P < 0.0001, respectively). Positive correlation was observed between serum levels of HCV core antigen and LDL‐C (P = 0.0147), with their levels negatively correlated to LDLR (P = 0.0270 and P = 0.0021, respectively). Immunohistochemically, hepatocellular expression of claudin‐1 and occludin was increased in HCV‐infected livers. Different levels of expression were demonstrated at the mRNA and protein levels for occludin and claudin‐1 in HCV‐infected and normal livers. Correlation of elements associated with viral entry was comparable in HCV‐infected and normal livers. J. Med. Virol. 83:921–927, 2011.

Therapeutic effect of bezafibrate against biliary damage: a study of phospholipid secretion via the PPARalpha-MDR3 pathway.

OBJECTIVE Bezafibrate (BF) has been used to treat biliary damage, particularly in patients with primary biliary cirrhosis (PBC), and its clinical efficacy has been demonstrated. The mechanism of action is thought to involve activation of the PPARalpha-MDR3-phospholipid (PL) secretion pathway. We tried to confirm this hypothesis in patients with hepatobiliary disease. METHODS The levels of serum gamma-glutamyl transpeptidase and alkaline phosphatase, and those of bile components were examined before and after BF administration in patients with obstructive jaundice undergoing percutaneous transhepatic biliary drainage (PTBD). Hepatic expression of PPARalpha and MDR3 was quantified by real-time PCR in patients with PBC or non-alcoholic fatty liver disease (NAFLD). RESULTS In patients with obstructive jaundice, BF decreased the serum levels of biliary enzymes and increased the bile concentration of PL. In patients with PBC or NAFLD, the expression levels of MDR3 were already up-regulated before starting the BF treatment. Although BF treatment did not further up-regulate MDR3 expression in NAFLD patients, PPARalpha expression was significantly increased. CONCLUSIONS BF enhanced the secretion of PL into bile in cholestatic patients undergoing PTBD. However, in patients with PBC or NAFLD, diseases that represent cholesterol overload, MDR3 was already expressed at a high level to compensate for bile acids overproduction, and its expression was hardly affected by BF. In patients with chronic liver diseases such as PBC, BF may induce clinical effects via mechanisms independent of PL secretion.

Add‐on therapy of pitavastatin and eicosapentaenoic acid improves outcome of peginterferon plus ribavirin treatment for chronic hepatitis C

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. J. Med. Virol. 85:250–260, 2013.

The state of cholesterol metabolism in the liver of patients with primary biliary cirrhosis: the role of MDR3 expression.

AimBecause dyslipidemia, such as hypercholesterolemia, is a characteristic of primary biliary cirrhosis (PBC), hepatic lipid metabolism may be disturbed in PBC patients. We examined the expression of lipid metabolism-associated genes in PBC liver.MethodsAll of the patients examined were in stage I or II PBC and without medication. RNA was isolated from liver specimens by needle biopsies of PBC patients and controls. The expression levels of various genes were measured by real-time RT-PCR. Multidrug resistance 3 (MDR3) expression was examined immunohistochemically. Statistical correlations between the gene expression levels and indices of blood testing were calculated.ResultsThe expression levels of sterol regulatory element-binding protein (SREBP) 2 and LDL receptor were significantly lower, and those of apolipoprotein B, microsomal triglyceride transfer protein, ATP-binding cassette G5, and liver X receptor α (LXRα) were significantly higher in the PBC liver than in the normal control liver. The expression levels of bile acid synthesis- and excretion-associated genes did not change, and those of farnesoid X receptor, peroxisome proliferator-activated receptor α, and SREBP-1c were similar between the PBC and normal liver. MDR3 gene expression levels in the PBC liver were more than 4-fold higher than those in the control liver. Immunohistochemically, strong canalicular staining for MDR3 was observed in the PBC liver. LXRα expression was positively correlated with MDR3 levels. Serum levels of γ-glutamyl transpeptidase (GGT) and IgM were negatively correlated with MDR3 levels.ConclusionsHepatocellular cholesterol metabolism was at least partially disturbed, even in the early stage of PBC. The most characteristic finding was a distinct elevation of MDR3 expression, and the MDR3 levels were negatively correlated with GGT and IgM levels.

Association between lipid accumulation and the cannabinoid system in Huh7 cells expressing HCV genes.

Evidence from clinical and laboratory studies has accumulated indicating that the activation of the cannabinoid system is crucial for steatosis, especially in non-alcoholic fatty liver disease. However, the association between hepatitis C virus (HCV) infection and the cannabinoid system has not been well investigated and it is unclear whether steatosis in chronic hepatitis C develops via activation of the endocannabinoid/cannabinoid receptor signaling pathway. In this study, we examined the expression of a cannabinoid receptor (CB1) and the lipid accumulation in the hepatic Huh7 cell line, expressing HCV genes. We utilized Huh7/Rep-Feo-1b cells stably expressing HCV non-structural proteins (NS) 3, NS4, NS5A, and NS5B, as well as Tet-On Core-2 cells, in which the HCV core protein expression is inducible. Significantly higher levels of stored triglycerides were found in Huh7/Rep-Feo-1b cells compared to Huh7 cells. Also, triglyceride accumulation and CB1 receptor expression were down-regulated in Huh7/Rep-Feo-1b cells after HCV reduction by IFNα. Moreover, lipid accumulation appeared to increase after CB1 agonist treatment, while it decreased after CB1 antagonist treatment, although significant differences were not found compared to untreated cells. In Tet-On Core-2 cells, induction of HCV core protein expression did not affect CB1 expression or triglyceride accumulation. The results of this study in cultured cells suggest that HCV infection may activate the cannabinoid system and precede steatosis, but the core protein by itself may not have any effect on the cannabinoid system.

Association of ITPA polymorphism with outcomes of peginterferon-α plus ribavirin combination therapy

AIM To analyzed the association between inosine triphosphatase (ITPA) (rs1127354) genotypes and sustained virological response (SVR) rates in peginterferon (Peg-IFN)α + ribavirin (RBV) treatment. METHODS Patients who underwent Peg-IFNα + RBV combination therapy were enrolled (n = 120) and they had no history of other IFN-based treatments. Variation in hemoglobin levels during therapy, cumulative reduction of RBV dose, frequency of treatment withdrawal, and SVR rates were investigated in each ITPA genotype. RESULTS In patients with ITPA CC genotype, hemoglobin decline was significantly greater and the percentage of patients in whom total RBV dose was < 60% of standard and/or treatment was withdrawn was significantly higher compared with CA/AA genotype. However, SVR rates were equivalent between CC and CA/AA genotypes, and within a subset of patients with Interleukin 28B (IL28B) (rs8099917) TT genotype, SVR rates tended to be higher in patients with ITPA CC genotype, although the difference was not significant. CONCLUSION ITPA CC genotype was a disadvantageous factor for Peg-IFNα + RBV treatment in relation to completion rates and RBV dose. However, CC genotype was not inferior to CA/AA genotype for SVR rates. When full-length treatment is accomplished, it is plausible that more SVR is achieved in patients with ITPA CC variant, especially in a background of IL28B TT genotype.

Pathophysiological analysis of primary biliary cirrhosis focusing on choline/phospholipid metabolism

Injury to biliary epithelial cells caused by disorders in bile composition may be the initial step in the pathogenesis of primary biliary cirrhosis (PBC). We therefore examined choline/phospholipid metabolism in livers of patients with PBC.