Norifumi Kawada

Daclatasvir Plus Asunaprevir for Chronic HCV Genotype 1b Infection

All‐oral combinations of direct‐acting antivirals may improve efficacy and safety outcomes for patients with hepatitis C virus (HCV) infection, particularly those who are poor candidates for current interferon/ribavirin‐based regimens. In this open‐label, phase 3 study, 135 interferon‐ineligible/intolerant and 87 nonresponder patients with chronic HCV genotype 1b infection were enrolled at 24 centers in Japan. Patients received daclatasvir 60 mg once daily plus asunaprevir 100 mg twice daily for 24 weeks. The primary endpoint was sustained virologic response 24 weeks after treatment (SVR24). This study is registered with ClinicalTrials.gov (NCT01497834). SVR24 was achieved by 87.4% of interferon‐ineligible/intolerant patients and 80.5% of nonresponder (null and partial) patients; rates were similar in cirrhosis (90.9%) and noncirrhosis (84.0%) patients, and in patients with IL28B CC (84.5%) or non‐CC (84.8%) genotypes. Fourteen patients in each group (12.6%) discontinued dual therapy, mainly due to adverse events or lack of efficacy. Nine nonresponder patients received additional treatment with peginterferon/ribavirin per protocol‐defined criteria. The rate of serious adverse events was low (5.9%) and varied among patients. The most common adverse events were nasopharyngitis, increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST), headache, diarrhea, and pyrexia. Conclusion: Interferon‐free, ribavirin‐free all‐oral therapy with daclatasvir and asunaprevir for 24 weeks is well tolerated and can achieve a high rate of SVR in patients with HCV genotype 1b who were ineligible, intolerant, or had not responded to prior interferon‐based therapy. (Hepatology 2014;59:2083–2091)

Characterization of a Stellate Cell Activation-associated Protein (STAP) with Peroxidase Activity Found in Rat Hepatic Stellate Cells

A proteome approach for the molecular analysis of the activation of rat stellate cell, a liver-specific pericyte, led to the discovery of a novel protein named STAP (stellate cellactivation-associated protein). We cloned STAP cDNA. STAP is a cytoplasmic protein with molecular weight of 21,496 and shows about 40% amino acid sequence homology with myoglobin. STAP was dramatically induced in in vivo activated stellate cells isolated from fibrotic liver and in stellate cells undergoingin vitro activation during primary culture. This induction was seen together with that of other activation-associated molecules, such as smooth muscle α-actin, PDGF receptor-β, and neural cell adhesion molecule. The expression of STAP protein and mRNA was augmented time dependently in thioacetamide-induced fibrotic liver. Immunoelectron microscopy and proteome analysis detected STAP in stellate cells but not in other hepatic constituent cells. Biochemical characterization of recombinant rat STAP revealed that STAP is a heme protein exhibiting peroxidase activity toward hydrogen peroxide and linoleic acid hydroperoxide. These results indicate that STAP is a novel endogenous peroxidase catabolizing hydrogen peroxide and lipid hydroperoxides, both of which have been reported to trigger stellate cell activation and consequently promote progression of liver fibrosis. STAP could thus play a role as an antifibrotic scavenger of peroxides in the liver.

MicroRNA-221/222 upregulation indicates the activation of stellate cells and the progression of liver fibrosis

Background MicroRNAs (miRNAs) are important in hepatic pathophysiology and the development of liver cancer. Objective To explore miRNAs that are regulated with the progression of liver fibrosis caused by chronic liver disease. Design The regulated miRNAs in human livers infected with hepatitis C virus were identified by microarray analysis. Their expression in human livers with non-alcoholic steatohepatitis, mouse livers from two fibrosis models and cultured stellate cells was validated by real-time RT-PCR. The regulation of miR-222 expression in stellate cells by nuclear factor kappa B (NF-κB) was assayed. Finally, the effects of an miR-222 precursor or inhibitor on the expression of cyclin-dependent kinase inhibitor 1B (CDKN1B) and the growth of LX-2 cells were determined. Results It was found that miR-199a-5p/199a-3p and miR-221/222 were upregulated in the human liver in a fibrosis progression–dependent manner. Among these miRNAs, miR-221/222 were upregulated in LX-2 cells and increased during the course of culture-dependent activation of mouse primary stellate cells, in a manner similar to the expression of α1(I) collagen and α-smooth muscle actin mRNAs. The expression of miR-221/222 increased in mouse models of liver fibrosis. In contrast, an NF-κB inhibitor significantly suppressed the miR-222 induction that was stimulated in culture by transforming growth factor α or tumour necrosis factor α. Although overexpression or downregulation of miR-222 failed to regulate the growth of LX-2 cells, miR-222 bound to the CDKN1B 3′UTR and regulated the expression of the corresponding protein. Conclusion miR-221/222 may be new markers for stellate cell activation and liver fibrosis progression.

Interferon alfa down-regulates collagen gene transcription and suppresses experimental hepatic fibrosis in mice.

The equilibrium between the production and degradation of collagen is rigorously controlled by a number of growth factors and cytokines. Interferon alfa (IFN‐α) is now widely used for the treatment of chronic hepatitis C, which can improve serum levels of fibrotic markers and the degree of hepatic fibrosis, not only in patients who responded to therapy but also in those in whom it is ineffective. These findings may suggest that IFN‐α possesses direct antifibrotic effects in addition to its antiviral activity. However, in contrast to IFN‐γ, which has been shown to suppress collagen gene transcription, little is known about the mechanisms responsible for the antifibrotic effects of IFN‐α. Here, we report that IFN‐α, when administered into transgenic mice harboring the α2(I) collagen gene (COL1A2) promoter sequence, significantly repressed promoter activation and prevented the progression of hepatic fibrosis induced by carbon tetrachloride injection. Transient transfection assays indicated that IFN‐α decreased the steady‐state levels of COL1A2 messenger RNA (mRNA) and inhibited basal and TGF‐β/Smad3‐stimulated COL1A2 transcription in activated hepatic stellate cells (HSC). These inhibitory effects of IFN‐α on COL1A2 transcription were exerted through the interaction between phosphorylated Stat1 and p300. Blocking of the IFN‐α signal by overexpressing the intracellular domain‐deleted IFN receptor increased basal COL1A2 transcription and abolished the inhibitory effects of IFN‐α. In conclusion, our results indicate that IFN‐α antagonizes the TGF‐β/Smad3‐stimulated COL1A2 transcription in vitro and suppresses COL1A2 promoter activation in vivo, providing a molecular basis for antifibrotic effects of IFN‐α. (Hepatology 2003;38:890–899).

Localization of oxidized phosphatidylcholine in nonalcoholic fatty liver disease: Impact on disease progression

Nonalcoholic steatohepatitis/nonalcoholic fatty liver disease is considered to be a hepatic manifestation of various metabolic disorders. However, its precise pathogenic mechanism is obscure. Oxidative stress and consequent lipid peroxidation seem to play a pivotal role in disease progression. In this study, we analyzed the localization of oxidized phosphatidylcholine (oxPC), a lipid peroxide that serves as a ligand for scavenger receptors, in livers of patients with this steatotic disorder. Specimens of non‐alcoholic fatty liver disease (15 autopsy livers with simple steatosis and 32 biopsy livers with steatohepatitis) were examined via immunohistochemistry and immunoelectron microscopy using a specific antibody against oxPC. In addition, scavenger receptor expression, hepatocyte apoptosis, iron deposition, and inflammatory cell infiltration in the diseased livers were also assessed. Oxidized phosphatidylcholine was mainly localized to steatotic hepatocytes and some macrophages/Kupffer cells. A few degenerative or apoptotic hepatocytes were also positive for oxPC. Immunoelectron microscopy showed oxPC localized to cytoplasmic/intracytoplasmic membranes including lipid droplets. Steatotic livers showed enhanced expression of scavenger receptors. The number of oxPC cells was correlated with disease severity and the number of myeloperoxidase‐positive neutrophils, but not with the degree of iron deposition. In conclusion, distinct localization of oxPC in liver tissues suggest that neutrophil myeloperoxidase‐derived oxidative stress may be crucial in the formation of oxPC and the progression of steatotic liver disease. (HEPATOLOGY 2006;43:506–514.)

Inflammation and fibrogenesis in steatohepatitis

Nonalcoholic fatty liver disease consists of a range of disorders characterized by excess accumulation of triglyceride within the liver. Whereas simple steatosis is clinically benign, nonalcoholic steatohepatitis (NASH) often progresses to cirrhosis. Inflammation and fibrogenesis are closely inter-related and are major targets of NASH research. Experimental data have shown that inflammation in NASH is caused by insulin resistance, systemic lipotoxicity due to overnutrition, lipid metabolites, the production of proinflammatory cytokines and adipokines by visceral adipose tissue, gut-derived bacteria, and oxidative stress. In NASH-associated fibrosis, the principal cell type responsible for extracellular matrix production is recognized as the hepatic stellate cell. Although the fibrotic mechanisms underlying NASH are largely similar to those observed in other chronic liver diseases, the altered patterns of circulating adipokines, the generation of oxidative stress, and the hormonal profile associated with the metabolic syndrome might play unique roles in the fibrogenesis associated with the disease. Information on the basic pathogenesis of NASH with a focus on the generation of inflammation and fibrosis will be discussed.

Validation of the FIB4 index in a Japanese nonalcoholic fatty liver disease population

BackgroundA reliable and inexpensive noninvasive marker of hepatic fibrosis is required in patients with nonalcoholic fatty liver disease (NAFLD). FIB4 index (based on age, aspartate aminotransferase [AST] and alanine aminotransferase [ALT] levels, and platelet counts) is expected to be useful for evaluating hepatic fibrosis. We validated the performance of FIB4 index in a Japanese cohort with NAFLD.MethodsThe areas under the receiver operating characteristic curves (AUROC) for FIB4 and six other markers were compared, based on data from 576 biopsy-proven NAFLD patients. Advanced fibrosis was defined as stage 3-4 fibrosis. FIB4 index was assessed as: age (yr) × AST (IU/L)/(platelet count (109/L) × √ALT (IU/L))ResultsAdvanced fibrosis was found in 64 (11%) patients. The AUROC for FIB4 index was superior to those for the other scoring systems for differentiating between advanced and mild fibrosis. Only 6 of 308 patients with a FIB4 index below the proposed low cut-off point (< 1.45) were under-staged, giving a high negative predictive value of 98%. Twenty-eight of 59 patients with a FIB4 index above the high cut-off point (> 3.25) were over-staged, giving a low positive predictive value of 53%. Using these cutoffs, 91% of the 395 patients with FIB-4 values outside 1.45-3.25 would be correctly classified. Implementation of the FIB4 index in the Japanese population would avoid 58% of liver biopsies.ConclusionThe FIB4 index was superior to other tested noninvasive markers of fibrosis in Japanese patients with NAFLD, with a high negative predictive value for excluding advanced fibrosis. The small number of cases of advanced fibrosis in this cohort meant that this study had limited power for validating the high cut-off point.

Adenovirus-mediated expression of BMP-7 suppresses the development of liver fibrosis in rats

Background: Liver cirrhosis, which is caused by the accumulation of extracellular matrix materials, is a serious clinical problem that can progress to hepatic failure. Transforming growth factor-β (TGFβ) plays a pivotal role in extracellular matrix production, but bone morphogenetic protein (BMP)-7, a member of the TGFβ superfamily, can antagonise the fibrogenic activity of TGFβ. Aim: In this study, we examined whether adenovirus-mediated overexpression of BMP-7 (Ad-BMP-7) antagonised the effect of TGFβ in vitro and in vivo. Methods and results: In primary cultured rat stellate cells and the LX-2 human stellate cell line, induction of BMP-7 by Ad-BMP-7 infection decreased the expression of collagen 1A2 mRNA and smooth muscle α-actin in the presence or absence of TGFβ, via Smad 1/5/8 phosphorylation. BMP-7 triggered the mRNA expression of inhibitors of differentiation 2 (Id2) in LX-2. Although endogenous expression of BMP-7 was hardly detectable, Smad1 and Id2 overexpression increased BMP-7 expression in LX-2. A liver fibrosis model was induced by the repetitive intraperitoneal injection of thioacetamide (200 mg/kg body weight) twice per week for up to 7 weeks. In rats administered Ad-BMP-7 via the tail vein, hydroxyproline content and the areas stained by Sirius red dye in the liver were significantly reduced compared to controls. Ad-Id2 also reduced fibrosis. Conclusion: These data demonstrate that BMP-7, Smad 1/5/8 and Ids interact to antagonise hepatic fibrogenesis.

Development of hepatocellular carcinoma in patients with chronic hepatitis C who had a sustained virological response to interferon therapy: a multicenter, retrospective cohort study of 1124 patients

Background: Interferon (IFN) improves hepatic inflammation/fibrosis and reduces the risk of hepatocellular carcinoma (HCC) in patients with chronic hepatitis C (CH‐C). However, HCC develops in some patients who have a sustained virological response (SVR) to IFN therapy. We designed this study to establish a follow‐up protocol for patients with CH‐C who have SVR to IFN therapy.

Regulation of endothelin-1 action on the perfused rat liver

Endothelin‐1 (ET‐1) was found to be a very potent stimulus for contraction and glycogenolysis in the perfused rat liver. At 1 nM it caused a dramatic increase in portal pressure of 22.1 ± 2.7 cm water and enhanced the glucose output up to 3‐fold. Extracellular Ca2+ and protein kinase C were involved in the signal transduction of ET‐1. ET‐1 action does not seem to be mediated by endogenous eicosanoids. The effects of ET‐1 were significantly reduced in the presence of 1 μM Iloprost, a prostaglandin I2 analogue, or by 100 μM sin‐1, a nitric oxide donor. In cultured hepatocytes, glycogenolysis was also stimulated by ET‐1 although to an extent too small to explain the high glucose output found in the perfused liver.