Yuichi Nozaki

Nonalcoholic Fatty Liver Disease: US-based Acoustic Radiation Force Impulse Elastography

PURPOSE To investigate the clinical usefulness of ultrasonography-based acoustic radiation force impulse (ARFI) elastography (ie, ARFI sonoelastography) in patients with a diagnosis of nonalcoholic fatty liver disease (NAFLD) and compare ARFI sonoelastography results with transient sonoelastography and serum fibrosis marker test results. MATERIALS AND METHODS Written informed consent was obtained from all subjects, and the local ethics committee approved the study. Fifty-four patients with a liver biopsy-confirmed diagnosis of NAFLD (mean age, 50.6 years +/- 13.7) were examined. All patients with NAFLD and healthy volunteers underwent ARFI sonoelastography, transient sonoelastography, and serum liver fibrosis marker testing (hyaluronic acids, type IV collagen 7 S domain). Ten healthy volunteers underwent ARFI sonoelastography. ARFI sonoelastography results were compared with liver biopsy findings, the reference standard. ARFI sonoelastography findings were compared with liver biopsy, transient sonoelastography, and serum fibrosis marker test results. Student t testing was used for univariate comparisons; Kruskal-Wallis testing, for assessments involving more than two independent groups; and areas under the receiver operating characteristic curve (A(z)), to assess the sensitivity and specificity of ARFI sonoelastography for detection of stage 3 and stage 4 fibrosis. RESULTS Median velocities in the patients with NAFLD were 1.040 m/sec for those with stage 0 fibrosis, 1.120 m/sec for those with stage 1, 1.130 m/sec for those with stage 2, 1.780 m/sec for those with stage 3, and 2.180 m/sec for those with stage 4. The A(z) for the diagnosis of hepatic fibrosis stages 3 or higher was 0.973 (optimal cutoff value, 1.77 m/sec; sensitivity, 100%; specificity, 91%), while that for the diagnosis of stage 4 fibrosis was 0.976 (optimal cutoff value, 1.90 m/sec; sensitivity, 100%; specificity, 96%). Significant correlations between median velocity measured by using ARFI sonoelastography and the following parameters were observed: liver stiffness measured with transient sonoelastography (r = 0.75, P < .0001), serum level of hyaluronic acid(r = 0.459, P = .0009), and serum level of type IV collagen 7 S domain (r = 0.445, P = .0015). CONCLUSION There is a significant positive correlation between median velocity measured by using ARFI sonoelastography and severity of liver fibrosis in patients with NAFLD. The results of ARFI sonoelastography were similar to those of transient sonoelastography.

High-sensitivity C-reactive protein is an independent clinical feature of nonalcoholic steatohepatitis (NASH) and also of the severity of fibrosis in NASH

BackgroundThe changes in nonalcoholic fatty liver disease (NAFLD) range over a wide spectrum, extending from steatosis to steatohepatitis (NASH). However, it has remained difficult to differentiate between NASH and nonprogressive NAFLD by clinical examination. We investigated the interrelationships between serum high-sensitivity C-reactive protein (hs-CRP) and the pathogenesis and progression of NASH.MethodsHs-CRP was measured in 100 patients with histologically verified NAFLD (29 with steatosis and 71 with NASH), and a real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was performed to measure the intrahepatic mRNA expressions of CRP and interleukin (IL)-6.ResultsThe results of a multiple regression analysis revealed that in comparison with cases of steatosis, hs-CRP was significantly elevated (P = 0.0048) in cases of NASH. Furthermore, among patients with NASH, hs-CRP was significantly elevated in those with advanced fibrosis compared with that in those with mild fibrosis (P = 0.0384), even after adjustment for age, sex, presence of diabetes, body mass index, visceral fat area, subcutaneous fat area, homeostasis model assessment for insulin resistance, high-density lipoprotein cholesterol, triglyceride, and low-density lipoprotein cholesterol. The results of the RT-PCR analysis showed that intrahepatic mRNA expression of CRP, but not IL-6, was increased in patients with NASH compared with those with steatosis (P = 0.0228).ConclusionsThis is the first report to demonstrate consistent and profound elevation of hs-CRP in cases of NASH compared with in cases of simple nonprogressive steatosis. Our results suggest that hs-CRP may be a clinical feature that not only distinguishes NASH from simple nonprogressive steatosis but also indicates the severity of hepatic fibrosis in cases of NASH.

Hyperresponsivity to Low-Dose Endotoxin during Progression to Nonalcoholic Steatohepatitis Is Regulated by Leptin-Mediated Signaling

Although bacterial endotoxin, such as lipopolysaccharide (LPS), plays a key role in the pathogenesis of nonalcoholic steatohepatitis (NASH), detailed mechanisms of this pathogenesis remain unclear. Here, we demonstrate that upregulation of CD14 by leptin-mediated signaling is critical to hyperreactivity against endotoxin during NASH progression. Upregulation of CD14 in Kupffer cells and hyperreactivity against low-dose LPS were observed in high-fat diet (HFD)-induced steatosis mice, but not chow-fed-control mice. Hyperresponsivity against low-dose LPS led to accelerated NASH progression, including liver inflammation and fibrosis. Administering leptin in chow-fed mice caused increased hepatic expression of CD14 via STAT3 signaling, resulting in hyperreactivity against low-dose LPS without steatosis. In contrast, a marked decrease in hepatic CD14 expression was observed in leptin-deficient ob/ob mice, despite severe steatosis. Our results indicate that obesity-induced leptin plays a crucial role in NASH progression via enhanced responsivity to endotoxin, and we propose a mechanism of bacteria-mediated progression of NASH.

Metformin suppresses azoxymethane‐induced colorectal aberrant crypt foci by activating AMP‐activated protein kinase

Metformin is widely used for the treatment of diabetes mellitus. Adenosine monophosphate‐activated protein kinase (AMPK) is known to be activated by metformin and to inhibit the mammalian target of rapamycin (mTOR) pathway. The mTOR pathway plays an important role in the protein translational machinery and cell proliferation. We examined the effect of metformin on the suppression of colorectal carcinogenesis in chemical carcinogen‐induced models. Seven‐wk‐old BALB/c mice were intraperitoneally (i.p.) injected with azoxymethane (AOM, 10 mg/kg) and then treated with or without metformin (250 mg/kg/d) for 6 wk (for the investigation of aberrant crypt foci [ACF] formation) or 32 wk (for polyp formation). We next investigated colonic epithelial proliferation using bromodeoxyuridine (BrdU) and the proliferating cell nuclear antigen (PCNA) labeling indices. Furthermore, to examine the indirect effect of metformin, the insulin resistance status and the serum lipid levels were assessed. Treatment with metformin significantly reduced ACF formation. The effect of metformin on colon polyp inhibition was relatively modest. No significant difference in body weight or glucose concentration was observed. The BrdU and PCNA indices decreased in mice treated with metformin. A Western blot analysis revealed that the phosphorylated mTOR, S6 kinase, and S6 protein levels in the colonic mucosa decreased significantly in mice treated with metformin. In conclusion, metformin suppresses colonic epithelial proliferation via the inhibition of the mTOR pathway through the activation of AMPK. As metformin is already used daily as an antidiabetic drug, it might be a safe and promising candidate for the chemoprevention of colorectal cancer.

Efficacy of ezetimibe for the treatment of non-alcoholic steatohepatitis : An open-label, pilot study

Aim:  Non‐alcoholic steatohepatitis (NASH) is considered a hepatic manifestation of metabolic syndrome. However, effective drug therapy for NASH has not been established yet. In the present study, we evaluated the efficacy of 6 months of ezetimibe treatment for NASH patients with dyslipidemia for the comparison of improvement of the clinical parameters and histological alterations.

Dysfunctional very-low-density lipoprotein synthesis and release is a key factor in nonalcoholic steatohepatitis pathogenesis†‡

The specific mechanisms of nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH) pathogenesis remain unknown. In the present study we investigated the differences between NAFL and NASH in terms of liver lipid metabolites and serum lipoprotein. In all, 104 Japanese subjects (50 men and 54 postmenopausal women) with histologically verified NAFL disease (NAFLD) (51 with NAFL, 53 with NASH) were evaluated; all diagnoses were based on liver biopsy findings and the proposed diagnostic criteria. To investigate the differences between NAFL and NASH in humans, we carefully examined (1) lipid inflow in the liver, (2) lipid outflow from the liver, (3) very‐low‐density lipoprotein (VLDL) synthesis in the liver, (4) triglyceride (TG) metabolites in the liver, and (5) lipid changes and oxidative DNA damage. Most of the hepatic lipid metabolite profiles were similar in the NAFL and NASH groups. However, VLDL synthesis and lipid outflow from the liver were impaired, and surplus TGs might have been produced as a result of lipid oxidation and oxidative DNA damage in the NASH group. Conclusion: A growing body of literature suggests that a deterioration in fatty acid oxidation and VLDL secretion from the liver, caused by the impediment of VLDL synthesis, might induce serious lipid oxidation and DNA oxidative damage, impacting the degree of liver injury and thereby contributing to the progression of NASH. Therefore, dysfunctional VLDL synthesis and release may be a key factor in progression to NASH. (HEPATOLOGY 2009.)

Long-term combination therapy of ezetimibe and acarbose for non-alcoholic fatty liver disease

BACKGROUND/AIMS Non-alcoholic fatty liver disease (NAFLD) is a hepatic manifestation of metabolic syndrome that is closely associated with multiple factors such as obesity, hyperlipidemia, type 2 diabetes mellitus and hypertension, making it difficult to treat NAFLD effectively using any monotherapy available to date. In this study, we propose a novel combination therapy for NAFLD comprising ezetimibe (EZ), a cholesterol absorption inhibitor, and acarbose (AC), an alpha-glucosidase inhibitor. METHODS C57BL/6J mice were divided into five treatment groups as follows: basal diet (BD), high-fat diet (HFD) only, HFD with EZ (5mg/kg/day), HFD with AC (100mg/kg/day), and HFD with both EZ and AC for 24 weeks. RESULTS Long-term combination therapy with EZ and AC significantly reduced steatosis, inflammation and fibrosis in the liver, compared with long-term monotherapy with either drug, in an HFD-induced NAFLD mouse model; the combination therapy also significantly increased the expression of microsomal triglyceride transfer protein (MTP) and peroxisome proliferators-activated receptor-alpha1 (PPAR-alpha1) in the liver, compared with either monotherapy, which may have led to the improvement in lipid metabolic disorder seen in this model. CONCLUSIONS Combination therapy with EZ and AC for 24 weeks improved the histopathological findings in a mouse model of NAFLD.

Hepatitis C virus directly associates with insulin resistance independent of the visceral fat area in nonobese and nondiabetic patients

Summary.  Insulin resistance (IR) is known to be associated with the visceral adipose tissue area. Elucidation of the relationship between hepatitis C virus (HCV) and IR is of great clinical relevance, because IR promotes liver fibrosis. In this study, we tested the hypothesis that HCV infection by itself may promote IR. We prospectively evaluated 47 patients with chronic HCV infection who underwent liver biopsy. Patients with obesity, type 2 diabetes mellitus (DM), or a history of alcohol consumption were excluded. IR was estimated by calculation of the modified homeostasis model of insulin resistance (HOMA‐IR) index. Abdominal fat distribution was determined by computed tomography. Fasting blood glucose levels were within normal range in all the patients. The results of univariate analysis revealed a significant correlation between the quantity of HCV‐RNA and the HOMA‐IR (r = 0.368, P = 0.0291). While a significant correlation between the visceral adipose tissue area and the HOMA‐IR was also observed in the 97 control, nondiabetic, non‐HCV‐infected patients (r = 0.398, P < 0.0001), no such significant correlation between the visceral adipose tissue area and the HOMA‐IR (r = 0.124, P = 0.496) was observed in the patients with HCV infection. Multiple regression analysis with adjustment for age, gender and visceral adipose tissue area revealed a significant correlation between the HCV‐RNA and the HOMA‐IR (P = 0.0446). HCV is directly associated with IR in a dose‐dependent manner, independent of the visceral adipose tissue area. This is the first report to demonstrate the direct involvement of HCV and IR in patients with chronic HCV infection.

Association between angiotensin II type 1 receptor polymorphisms and the occurrence of nonalcoholic fatty liver disease.

Background: Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver injury in many countries. Genetic factors are important for the development of NAFLD, as well as environmental factors. Recently an angiotensin II type 1 receptor (AGTR1) has been recognized as important in the aetiology of fibrosis in the liver.

Incidence of Small Bowel Injury Induced by Low-Dose Aspirin: A Crossover Study Using Capsule Endoscopy in Healthy Volunteers

Background and Aims: Small intestinal toxicity of low-dose aspirin remains unclear. The purpose of this capsule endoscopy study was to assess the incidence of small bowel injury in healthy volunteers treated with short-term low-dose aspirin. Methods: Healthy subjects were randomly assigned to receive low-dose aspirin for 14 days (Aspirin group) or no drugs for 14 days (Control group). The two treatment occasions were separated by a washout period of at least 4 weeks. All subjects underwent capsule endoscopy at the end of each treatment period. Results: After 2 weeks of treatment, the percentages of subjects with small bowel pathology were 80% in the Aspirin group compared with 20% in the Control group (p = 0.023). The incidence of small bowel mucosal breaks in the Aspirin group was higher than that in the Control group, although the difference was not significant (30 vs. 0%; p = 0.210). Conclusions: This is the first pilot study using capsule endoscopy to report on the relation between small bowel injury and low-dose aspirin. Among the healthy subjects, the short-term administration of low-dose aspirin was associated with a mild mucosal inflammation of the small bowel.