Hirotoshi Ebinuma

Acoustic Radiation Force Impulse Elastography for fibrosis evaluation in patients with chronic hepatitis C: An international multicenter study

AIM The aim of this international multicenter study was to evaluate the reliability of Acoustic Radiation Force Impulse (ARFI) elastography for predicting fibrosis severity, in patients with chronic hepatitis C. PATIENTS AND METHODS We compared ARFI to liver biopsy (LB) in 914 patients (10 centers, 5 countries) with chronic hepatitis C. In each patient LB (evaluated according to the METAVIR score) and ARFI measurements were performed (median of 5-10 valid measurements, expressed in meters/second - m/s). In 400 from the 914 patients, transient elastography (TE) was also performed (median of 6-10 valid measurements, expressed in kiloPascals - kPa). RESULTS Valid ARFI measurements were obtained in 911 (99.6%) of 914 cases. On LB 61 cases (6.7%) had F0, 241 (26.4%) had F1, 202 (22.1%) had F2, 187 (20.4%) had F3, and 223 (24.4%) had F4 fibrosis. A highly significant correlation (r=0.654) was found between ARFI measurements and fibrosis (p<0.0001). The predictive values of ARFI for various stages of fibrosis were: F ≥ 1 - cut-off>1.19 m/s (AUROC=0.779), F ≥ 2 - cut-off>1.33 m/s (AUROC=0.792), F ≥ 3 - cut-off>1.43 m/s (AUROC=0.829), F=4 - cut-off>1.55 m/s (AUROC=0.842). The correlation with histological fibrosis was not significantly different for TE in comparison with ARFI elastography: r=0.728 vs. 0.689, p=0.28. TE was better than ARFI for predicting the presence of liver cirrhosis (p=0.01) and fibrosis (F ≥ 1, METAVIR) (p=0.01). CONCLUSION ARFI elastography is a reliable method for predicting fibrosis severity in chronic hepatitis C patients.

Free cholesterol accumulation in hepatic stellate cells: Mechanism of liver fibrosis aggravation in nonalcoholic steatohepatitis in mice

Although nonalcoholic steatohepatitis (NASH) is associated with hypercholesterolemia, the underlying mechanisms of this association have not been clarified. We aimed to elucidate the precise role of cholesterol in the pathophysiology of NASH. C57BL/6 mice were fed a control, high‐cholesterol (HC), methionine‐choline‐deficient (MCD), or MCD+HC diet for 12 weeks or a control, HC, high‐fat (HF), or HF+HC diet for 24 weeks. Increased cholesterol intake accelerated liver fibrosis in both the mouse models without affecting the degree of hepatocellular injury or Kupffer cell activation. The major causes of the accelerated liver fibrosis involved free cholesterol (FC) accumulation in hepatic stellate cells (HSCs), which increased Toll‐like receptor 4 protein (TLR4) levels through suppression of the endosomal‐lysosomal degradation pathway of TLR4, and thereby sensitized the cells to transforming growth factor (TGF)β‐induced activation by down‐regulating the expression of bone morphogenetic protein and activin membrane‐bound inhibitor. Mammalian‐cell cholesterol levels are regulated by way of a feedback mechanism mediated by sterol regulatory element‐binding protein 2 (SREBP2), maintaining cellular cholesterol homeostasis. Nevertheless, HSCs were sensitive to FC accumulation because the high intracellular expression ratio of SREBP cleavage‐activating protein (Scap) to insulin‐induced gene (Insig) disrupted the SREBP2‐mediated feedback regulation of cholesterol homeostasis in these cells. HSC activation subsequently enhanced the disruption of the feedback system by Insig‐1 down‐regulation. In addition, the suppression of peroxisome proliferator‐activated receptor γ signaling accompanying HSC activation enhanced both SREBP2 and microRNA‐33a signaling. Consequently, FC accumulation in HSCs increased and further sensitized these cells to TGFβ‐induced activation in a vicious cycle, leading to exaggerated liver fibrosis in NASH. Conclusion: These characteristic mechanisms of FC accumulation in HSCs are potential targets to treat liver fibrosis in liver diseases including NASH. (Hepatology 2014;58:154–169)

A High-Cholesterol Diet Exacerbates Liver Fibrosis in Mice via Accumulation of Free Cholesterol in Hepatic Stellate Cells

BACKGROUND & AIMS Some studies have indicated that dietary cholesterol has a role in the progression of liver fibrosis. We investigated the mechanisms by which dietary cholesterol might contribute to hepatic fibrogenesis. METHODS C57BL/6 mice were fed a high-cholesterol diet or a control diet for 4 weeks; liver fibrosis then was induced by bile-duct ligation or carbon tetrachloride administration. Hepatic stellate cells (HSCs) were isolated from mice fed high-cholesterol diets or from Niemann-Pick type C1-deficient mice, which accumulate intracellular free cholesterol. RESULTS After bile-duct ligation or carbon tetrachloride administration, mice fed high-cholesterol diets had significant increases in liver fibrosis and activation of HSCs compared with mice fed control diets. There were no significant differences in the degree of hepatocellular injury or liver inflammation, including hepatocyte apoptosis or Kupffer cell activation, between mice fed high-cholesterol or control diets. Levels of free cholesterol were much higher in HSCs from mice fed high-cholesterol diets than those fed control diets. In cultured HSCs, accumulation of free cholesterol in HSCs increased levels of Toll-like receptor 4 (TLR4), leading to down-regulation of bone morphogenetic protein and activin membrane-bound inhibitor (a pseudoreceptor for transforming growth factor [TGF]β); the HSCs became sensitized to TGFβ-induced activation. Liver fibrosis was not aggravated by the high-cholesterol diet in C3H/HeJ mice, which express a mutant form of TLR4; HSCs that express mutant TLR4 were not activated by accumulation of free cholesterol. CONCLUSIONS Dietary cholesterol aggravates liver fibrosis because free cholesterol accumulates in HSCs, leading to increased TLR4 signaling, down-regulation of bone morphogenetic protein and activin membrane-bound inhibitor, and sensitization of HSC to TGFβ. This pathway might be targeted by antifibrotic therapies.

Evaluation of liver fibrosis by transient elastography using acoustic radiation force impulse: comparison with Fibroscan ®

BackgroundAccurate evaluation of liver fibrosis in patients with chronic liver damage is required to determine the appropriate treatment. Various approaches, including laboratory tests and transient elastography, have been used to evaluate liver fibrosis. Recently, transient elastography with acoustic radiation force impulse (ARFI) has been developed and applied with conventional ultrasonography. The aim of this study was to evaluate the clinical utility of transient elastography with ARFI and to compare the results with this method and those of the Fibroscan® procedure.MethodsOne hundred and thirty-one patients with liver damage, who underwent liver biopsy at our department, were enrolled prospectively in this study. Elastography with ARFI (applied with ACUSON S2000®), and Fibroscan® was performed at the same time as liver biopsy. These measurements were compared with histological findings in liver biopsy specimens, and measurement accuracy was evaluated by receiver-operating characteristic analysis.ResultsElastography values with both procedures were significantly correlated with the stages of liver fibrosis and there was little difference in the results obtained using the 2 procedures. The accuracy of differential diagnosis between no fibrosis at F0 and more than F1 stage was insufficient with ARFI, but this procedure was sufficient for diagnosing advanced fibrosis. The accuracy of ARFI was almost equivalent to that of the Fibroscan® method. Moreover, both ARFI and Fibroscan® values increased in proportion to the severity of hepatic inflammation when fibrosis stage is low, but not in proportion to the severity of steatosis.ConclusionsTransient elastography with ARFI is simple, non-invasive and useful for diagnosing the stage of fibrosis in chronic liver disease. The utility of ARFI was almost equivalent to that of the Fibroscan® method.

Reactivation of hepatitis B in a patient with Crohn’s disease treated using infliximab

We encountered a case of reactivation of hepatitis B virus after administration of infliximab for Crohn’s disease. The use of infliximab was considered because the patient displayed abdominal symptoms and perianal lesions. Transaminases were normal, and hepatitis B virus (HBV) DNA was undetectable before treatment, so no antiviral treatment was used, and infliximab and low-dose 6-mercaptopurine were administered. This treatment was effective, but liver dysfunction and reactivation of HBV were observed after the fourth injection of infliximab. This is the first report of Crohn’s disease for which infliximab use was continued even after reactivation of HBV was observed. However, liver dysfunction was not improved by lamivudine. Antiviral treatment should be considered before administration of infliximab for patients with HBV.

CD18/ICAM-1-dependent oxidative NF-kappaB activation leading to nitric oxide production in rat Kupffer cells cocultured with syngeneic hepatoma cells.

Previous studies have indicated that nitric oxide (NO) released from Kupffer cells modulates biological viability of cocultured hepatoma cells. This study was designed to evaluate the mechanisms by which Kupffer cells synthesize and release NO in reponse to cocultured hepatoma cells. Kupffer cells isolated from male Wistar rats were cocultured with rat hepatoma cell line, AH70 cells. The sum of nitrite and nitrate levels increased in the culture medium of Kupffer cells with AH70 cells as compared with those of Kupffer cells or AH70 cells alone. Increased expressions of iNOS and iNOS mRNA in Kupffer cells cocultured with AH70 cells were detected by an immunofluorescence staining and a fluorescence in situ hybridization study, respectively. A fluorescence in situ DNA-protein binding assay revealed that NF-kappaB activation occurs in Kupffer cells and activated NF-kappaB moved into the nuclei preceding to an increased production of NO. Oxidative stress indicated by dichlorofluorescein fluorescence was observed in Kupffer cells cocultured with AH70 cells. An increased calcium mobilization indicated as increased fluo-3-associated fluorescence was also induced in Kupffer cells after coculture with AH70 cells. Monoclonal antibodies directed against rat CD18 and ICAM-1, as well as TMB-8, a calcium inhibitor, prevented the calcium mobilization, active oxygen production, and NF-kappaB activation in addition to the increased production of NO. Pyrrolidine dithiocarbamate, an inhibitor of oxidative NF-kappaB activation, diphenylene iodonium, an NADPH oxidase inhibitor, and quinacrine, a phospholipase A2 inhibitor, significantly attenuated the increase in dichlorofluorescein fluorescence, NF-kappaB activation, and NO production. Therefore, this study suggests that CD18/ICAM-1-dependent cell-to-cell interaction with hepatoma cells causes calcium mobilization and oxidative activation of NF-kappaB, which may lead to the increased production of NO in Kupffer cells.

The influence of aminotransferase levels on liver stiffness assessed by Acoustic Radiation Force Impulse Elastography: A retrospective multicentre study

BACKGROUND Acoustic Radiation Force Impulse Elastography is a new method for non-invasive evaluation of liver fibrosis. AIM To evaluate the impact of elevated alanine aminotransferase levels on liver stiffness assessment by Acoustic Radiation Force Impulse Elastography. METHODS A multicentre retrospective study including 1242 patients with chronic liver disease, who underwent liver biopsy and Acoustic Radiation Force Impulse. Transient Elastography was also performed in 512 patients. RESULTS The best Acoustic Radiation Force Impulse cut-off for predicting significant fibrosis was 1.29 m/s in cases with normal alanine aminotransferase levels and 1.44 m/s in patients with alanine aminotransferase levels>5 × the upper limit of normal. The best cut-off for predicting liver cirrhosis were 1.59 and 1.75 m/s, respectively. Acoustic Radiation Force Impulse cut-off for predicting significant fibrosis and cirrhosis were relatively similar in patients with normal alanine aminotransferase and in those with alanine aminotransferase levels between 1.1 and 5 × the upper limit of normal: 1.29 m/s vs. 1.36 m/s and 1.59 m/s vs. 1.57 m/s, respectively. For predicting cirrhosis, the Transient Elastography cut-offs were significantly higher in patients with alanine aminotransferase levels between 1.1 and 5 × the upper limit of normal compared to those with normal alanine aminotransferase: 12.3 kPa vs. 9.1 kPa. CONCLUSION Liver stiffness values assessed by Acoustic Radiation Force Impulse and Transient Elastography are influenced by high aminotransferase levels. Transient Elastography was also influenced by moderately elevated aminotransferase levels.

CCR9 Macrophages Are Required for Acute Liver Inflammation in Mouse Models of Hepatitis

BACKGROUND & AIMS Antigen-presenting cells (APCs) are involved in the induction of liver inflammation. We investigated the roles of specific APCs in the pathogenesis of acute liver injury in mice. METHODS We used concanavalin A (con A) or carbon tetrachloride to induce acute liver inflammation in mice and studied the roles of macrophages that express CCR9. RESULTS After injection of con A, we detected CCR9(+)CD11b(+)CD11c(-) macrophages that express tumor necrosis factor (TNF)-α in livers of mice, whereas CCR9(+)Siglec-H(+)CD11b(-)CD11c(low) plasmacytoid DCs (pDCs), which are abundant in normal livers, disappeared. The CCR9(+) macrophages were also detected in the livers of RAG-2(-/-) mice, which lack lymphocytes and natural killer T cells, after injection of con A. Under inflammatory conditions, CCR9(+) macrophages induced naive CD4(+) T cells to become interferon gamma-producing Th1 cells in vivo and in vitro. CCR9(-/-) mice injected with con A did not develop hepatitis unless they also received CCR9(+) macrophages from mice that received con A; more CCR9(+) macrophages accumulated in their inflamed livers than CCR9(+) pDCs, CCR9(-) pDCs, or CCR9(-) macrophages isolated from mice that had received injections of con A. Levels of CCL25 messenger RNA increased in livers after injection of con A; neutralizing antibodies against CCL25 reduced the induction of hepatitis by con A by blocking the migration of CCR9(+) macrophages and their production of TNF-α. Peripheral blood samples from patients with acute hepatitis had greater numbers of TNF-α-producing CCR9(+)CD14(+)CD16(high) monocytes than controls. CONCLUSIONS CCR9(+) macrophages contribute to the induction of acute liver inflammation in mouse models of hepatitis.

Overexpression of Bcl-2 protects human hepatoma cells from Fas-antibody-mediated apoptosis.

BACKGROUND/AIMS Fas is a cell surface antigen, that triggers apoptosis upon specific ligand or antibody binding. The proto-oncogene bcl-2 prevents apoptosis induced by various treatments. The aim of our study was to evaluate whether Bcl-2 protects hepatoma cells from Fas-mediated apoptosis. METHODS Two human cell lines, HCC-T and HepG2 were used. Expression of Fas antigen and Bcl-2 was detected by flow cytometry and Western blotting. Cell viability and apoptotic change were examined after anti-Fas- and antisense oligodeoxynucleotide treatments. Apoptotic cells were detected by nick-end labelling and the TUNEL method. To test if Bcl-2 expression can protect HepG2 cells from Fas-mediated apoptosis, the cells were transduced using retroviral vector, LZBC, designed to coexpress E. coli beta-galactosidase and human Bcl-2. To further confirm the protective effect of Bcl-2 expression against Fas-mediated apoptosis in HepG2, Bcl-2 expressing plasmid vector was produced and a cell line stably expressing Bcl-2 was cloned. RESULTS Western blot analysis showed constitutive Bcl-2 expression in HCC-T cells, but not in HepG2 cells. HCC-T was resistant to apoptosis after treatment with an agonist anti-Fas antibody (1 microg/ml for 3 days), whereas 33% of the HepG2 cells were killed by this treatment. Inhibition of Bcl-2 expression by transfection of antisense oligodeoxynucleotides caused spontaneous apoptosis in HCC-T, but not in HepG2 cells, suggesting that Bcl-2 is essential for survival of HCC-T cells, whereas other proteins may substitute for it in HepG2 cells. Following LZBC infection, 10% HepG2 cells were beta-galactosidase-positive by X-gal staining and Bcl-2-positive. In cells surviving after anti-Fas treatment, the proportion of beta-galactosidase-positive cells increased to 50% and the beta-galactosidase activity increased 6-fold, indicating that Bcl-2 expression protected the cells from Fas-mediated apoptosis. In the cloned HepG2 cells stably expressing Bcl-2, the extent of Fas-mediated apoptosis was inversely related to the level of Bcl-2 expression. CONCLUSION Bcl-2 confers protection to human hepatoma cells against Fas-mediated apoptosis, and is essential for survival of some, but not all, hepatoma cells.

p53/p66Shc-mediated signaling contributes to the progression of non-alcoholic steatohepatitis in humans and mice

BACKGROUND & AIMS The tumor suppressor p53 is a primary sensor of stressful stimuli, controlling a number of biologic processes. The aim of our study was to examine the roles of p53 in non-alcoholic steatohepatitis (NASH). METHODS Male wild type and p53-deficient mice were fed a methionine- and choline-deficient diet for 8 weeks to induce nutritional steatohepatitis. mRNA expression profiles in normal liver samples and liver samples from patients with non-alcoholic liver disease (NAFLD) were also evaluated. RESULTS Hepatic p53 and p66Shc signaling was enhanced in the mouse NASH model. p53 deficiency suppressed the enhanced p66Shc signaling, decreased hepatic lipid peroxidation and the number of apoptotic hepatocytes, and ameliorated progression of nutritional steatohepatitis. In primary cultured hepatocytes, transforming growth factor (TGF)-β treatment increased p53 and p66Shc signaling, leading to exaggerated reactive oxygen species (ROS) accumulation and apoptosis. Deficient p53 signaling inhibited TGF-β-induced p66Shc signaling, ROS accumulation, and hepatocyte apoptosis. Furthermore, expression levels of p53, p21, and p66Shc were significantly elevated in human NAFLD liver samples, compared with results obtained with normal liver samples. Among NAFLD patients, those with NASH had significantly higher hepatic expression levels of p53, p21, and p66Shc compared with the group with simple steatosis. A significant correlation between expression levels of p53 and p66Shc was observed. CONCLUSIONS p53 in hepatocytes regulates steatohepatitis progression by controlling p66Shc signaling, ROS levels, and apoptosis, all of which may be regulated by TGF-β. Moreover, p53/p66Shc signaling in the liver appears to be a promising target for the treatment of NASH.