Manabu Kishina

Therapeutic effects of angiotensin II type 1 receptor blocker, irbesartan, on non-alcoholic steatohepatitis using FLS-ob/ob male mice

Non-alcoholic steatohepatitis (NASH) is the hepatic manifestation of a metabolic syndrome characterized by accumulation of hepatic fat, inflammation and varying degrees of fibrosis. Angiotensin (AT)-II has been reported to play a role in the establishment of NASH. This study examined the effects of an AT-II receptor blocker, irbesartan, on NASH using fatty liver Shionogi (FLS)-ob/ob male mice as the closest animal model of human metabolic syndrome-related NASH. Irbesartan (30 mg/kg/day) was orally administered to FLS-ob/ob mice for 12 weeks (irbesartan group). The effects of irbesartan on steatohepatitis were examined using factors including steatosis, fibrosis, inflammation and oxidative stress. The areas of hepatic fibrosis and hepatic hydroxyproline content were significantly lower in the irbesartan group compared to controls. The areas of α-smooth muscle actin-positivity and F4/80-positive cells were significantly decreased in the irbesartan group. The percentage of 8-hydroxy-2-deoxyguanosine (8-OHdG)-positive cells and 8-OHdG DNA content were significantly decreased in the irbesartan group compared to controls. Levels of RNA expression for procollagen I, transforming growth factor β1, tumor necrosis factor-α, sterol regulatory element-binding protein 1c and fatty acid synthase were significantly lower in the irbesartan group compared to controls. In contrast, the gene expression of peroxisome proliferator activated receptor-α was significantly higher in the irbesartan group compared to controls. Irbesartan administration improved hepatic steatosis and attenuated the progression of hepatic fibrosis by inhibiting the activation of hepatic stellate cells and Kupffer cells and reducing oxidative stress.

Assessment of ablative margin by unenhanced magnetic resonance imaging after radiofrequency ablation for hepatocellular carcinoma

PURPOSE The aim of this study was to evaluate the feasibility of magnetic resonance imaging (MRI) without a contrast agent to visualize the ablative margin after radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC), compared with enhanced CT. METHODS Twenty-five HCCs in 19 patients were treated by RFA. T1-weighted MRI was performed before and after RFA, and the signal intensities of the tumors and surrounding liver tissues were measured. Treatment efficacy was assessed based on three grades: margin (+), a continuous high-intensity rim around the index tumor; margin zero, a partially discontinuous high-intensity rim; margin (-), the tumor extends beyond the high-intensity rim. RESULTS Twelve (86%) of fourteen low-intensity tumors on the pre-MRI were visualized as low-intensity tumors on post-MRI, and the ablative margins were visualized as high-intensity rims. Two (67%) of three high-intensity tumors on pre-MRI were visualized as higher-intensity tumors in the high-intensity ablative margin. Because the signal intensities of tumors and surrounding tissues in 14 tumors that were low- or high-intensity tumors on pre-MRI increased to the same extent, the tumors and ablative margin could be distinguished on post images. In 6 (75%) of the 8 iso-intensity tumors on pre-MRI, the ablative margin and tumor could also not be discriminated on post-MRI. The overall agreement between MRI and CT for the ablative margin was good (κ coefficient=0.716, p=0.00002). CONCLUSION In 82% of low- or high-intensity tumors on pre-MRI, post-MRI without a contrast agent enabled visualization of the ablative margin as a high-intensity rim, and it was possible to evaluate the ablative margin earlier and easier than with enhanced CT.

Usefulness of contrast-enhanced ultrasound with Sonazoid for evaluating liver abscess in comparison with conventional B-mode ultrasound

The purpose of this study was to evaluate the usefulness of contrast‐enhanced ultrasound (CEUS) with Sonazoid (perfluorobutane) in patients with liver abscess. Sonazoid is a contrast agent with a low mechanical index and is phagocytosed by Kupffer cells.

Therapeutic effects of the direct renin inhibitor, aliskiren, on non‐alcoholic steatohepatitis in fatty liver Shionogi ob/ob male mice

Non‐alcoholic steatohepatitis (NASH) is a manifestation of metabolic syndrome in the liver that is characterized by hepatic fat accumulation, inflammation and varying degrees of fibrosis. The renin–angiotensin system (RAS) appears to play important roles in NASH. Direct renin inhibitors (DRI) reduce plasma renin activity (PRA) through interaction with the active site of the enzyme and reduce the formation of angiotensin‐II (AT‐II). Therefore, the DRI aliskiren may further suppress the RAS. This study examined the effects of aliskiren on NASH in fatty liver Shionogi (FLS)‐ob/ob male mice that are the closest animal model of metabolic syndrome‐related NASH in humans.

Fatty liver Shionogi‐ob/ob mouse: A new candidate for a non‐alcoholic steatohepatitis model

The fatty liver Shionogi (FLS) mouse develops hereditary fatty liver without obesity. The FLS‐ob/ob mouse made by transferring the leptinob gene demonstrates several metabolic disorders and marked fat deposition in the liver. The aim was to evaluate which mouse model, the FLS or FLS‐ob/ob, is more useful for non‐alcoholic steatohepatitis research.

Therapeutic effects of the dipeptidyl peptidase-IV inhibitor, sitagliptin, on non-alcoholic steatohepatitis in FLS-ob/ob male mice

Non-alcoholic steatohepatitis is characterized by hepatic fat accumulation, inflammation and varying degrees of fibrosis. The dipeptidyl peptidase‑IV enzyme is important in glucose metabolism, as well as lipid accumulation, extracellular matrix metabolism and immune stimulation. Furthermore, the enzyme activity of dipeptidyl peptidase‑IV is known to be increased in non‑alcoholic steatohepatitis. Therefore, dipeptidyl peptidase‑IV inhibitors are potential therapeutic agents for non‑alcoholic steatohepatitis. The present study assessed the therapeutic effects of sitagliptin, a dipeptidyl peptidase‑IV inhibitor, on non‑alcoholic steatohepatitis using fatty liver Shionogi‑ob/ob male mice. Sitagliptin (2 mg/kg/day; n=10) or placebo (control; n=10) was orally administered to fatty liver Shionogi‑ob/ob mice for 12 weeks, and hepatic steatosis, fibrosis, inflammation and oxidative stress were assessed in comparison with the controls. Sitagliptin administration reduced body weight and blood glucose levels, and improved hepatic fibrosis. It also inhibited the gene expression levels of fatty acid synthase, transforming growth factor‑β1, tissue inhibitor of metalloproteinases‑1, procollagen‑type 1, tumor necrosis factor‑α, monocyte chemoattractant protein‑1 and enhanced peroxisome proliferator activated receptor‑α. Furthermore, a marked attenuation of hepatic stellate cell activation and Kupffer cells was observed in the sitagliptin group. A decrease in oxidative stress and apoptosis was also observed. Sitagliptin attenuated the progression of hepatic fibrosis by improving lipid metabolism, inflammation and oxidative stress in non-alcoholic steatohepatitis.

Clinical usefulness of the ablative margin assessed by magnetic resonance imaging with Gd-EOB-DTPA for radiofrequency ablation of hepatocellular carcinoma

BACKGROUND & AIMS The aim of this study was to investigate the feasibility of ablative margin (AM) grading by magnetic resonance imaging (MRI) with Gd-EOB-DTPA administered prior to radiofrequency ablation (RFA), and to identify factors for achieving a sufficient AM and predictors for local tumor progression. METHODS A total of 124 hepatocellular carcinomas (HCCs) were treated by RFA after Gd-EOB-DTPA administration. MRI and enhanced CT were performed within seven hours and one month after RFA. The AM assessment was categorized using three grades: AM (+), low-intensity area with continuous high-intensity rim; AM zero, low-intensity area with discontinuous high-intensity rim; and AM (-), low-intensity area extends beyond the high-intensity rim. Patients were followed and local tumor progression was observed. RESULTS AM (+), AM zero, AM (-), and indeterminate were found in 34, 33, 26, and 31 nodules, respectively. The overall agreement rate between MRI and enhanced CT for the diagnosis of AM was 56.8%. The κ coefficient was 0.326 (p<0.001), indicating moderate agreement. Multivariate logistic regression analysis showed that a significant factor for the achievement of AM (+) on MRI was no contiguous vessels. The cumulative local tumor progression rates (0% at 1, 2, and 3 years) in 33 AM (+) nodules were significantly lower than those (3.6%, 11.5%, and 18.3% at 1, 2, and 3 years respectively) in 32 AM zero nodules. A multivariate Cox proportional hazards model identified tumor size as an independent predictor for local tumor progression. CONCLUSION Gd-EOB-DTPA-MRI enabled an early assessment of RFA effectiveness in the majority ofHCC nodules. Local tumor progression was not detected in AM (+) nodules during the follow-up.

Nimesulide, a cyclooxygenase-2 selective inhibitor, suppresses obesity-related non-alcoholic fatty liver disease and hepatic insulin resistance through the regulation of peroxisome proliferator-activated receptor γ

Cyclooxygenase (COX)-2 selective inhibitors suppress non-alcoholic fatty liver disease (NAFLD); however, the precise mechanism of action remains unknown. The aim of this study was to examine how the COX-2 selective inhibitor nimesulide suppresses NAFLD in a murine model of high-fat diet (HFD)-induced obesity. Mice were fed either a normal chow diet (NC), an HFD, or HFD plus nimesulide (HFD-nime) for 12 weeks. Body weight, hepatic COX-2 mRNA expression and triglyceride accumulation were significantly increased in the HFD group. Triglyceride accumulation was suppressed in the HFD-nime group. The mRNA expression of hepatic peroxisome proliferator-activated receptor γ (PPARγ) and the natural PPARγ agonist 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) were significantly increased in the HFD group and significantly suppressed in the HFD-nime group. Glucose metabolism was impaired in the HFD group compared with the NC group, and it was significantly improved in the HFD-nime group. In addition, the plasma insulin levels in the HFD group were increased compared with those in the NC group, and were decreased in the HFD-nime group. These results indicate that HFD-induced NAFLD is mediated by the increased hepatic expression of COX-2. We suggest that the production of 15d-PGJ2, which is mediated by COX-2, induces NAFLD and hepatic insulin resistance by activating PPARγ. Furthermore, the mRNA expression of tissue inhibitor of metalloproteinases-1 (TIMP-1), procollagen-1 and monocyte chemoattractant protein-1 (MCP-1), as well as the number of F4/80-positive hepatic (Kupffer) cells, were significantly increased in the HFD group compared with the NC group, and they were reduced by nimesulide. In conclusion, COX-2 may emerge as a molecular target for preventing the development of NAFLD and insulin resistance in diet-related obesity.

Antifibrotic effects of ambrisentan,an endothelin-A receptor antagonist,in a non-alcoholic steatohepatitis mouse model

AIM To examine the effects of the endothelin type A receptor antagonist ambrisentan on hepatic steatosis and fibrosis in a steatohepatitis mouse model. METHODS Fatty liver shionogi (FLS) FLS-ob/ob mice (male, 12 wk old) received ambrisentan (2.5 mg/kg orally per day; n = 8) or water as a control (n = 5) for 4 wk. Factors were compared between the two groups, including steatosis, fibrosis, inflammation, and endothelin-related gene expression in the liver. RESULTS In the ambrisentan group, hepatic hydroxyproline content was significantly lower than in the control group (18.0 μg/g ± 6.1 μg/g vs 33.9 μg/g ± 13.5 μg/g liver, respectively, P = 0.014). Hepatic fibrosis estimated by Sirius red staining and areas positive for α-smooth muscle actin, indicative of activated hepatic stellate cells, were also significantly lower in the ambrisentan group (0.46% ± 0.18% vs 1.11% ± 0.28%, respectively, P = 0.0003; and 0.12% ± 0.08% vs 0.25% ± 0.11%, respectively, P = 0.047). Moreover, hepatic RNA expression levels of procollagen-1 and tissue inhibitor of metalloproteinase-1 (TIMP-1) were significantly lower by 60% and 45%, respectively, in the ambrisentan group. Inflammation, steatosis, and endothelin-related mRNA expression in the liver were not significantly different between the groups. CONCLUSION Ambrisentan attenuated the progression of hepatic fibrosis by inhibiting hepatic stellate cell activation and reducing procollagen-1 and TIMP-1 gene expression. Ambrisentan did not affect inflammation or steatosis.