Tatsuki Ichikawa

Short interfering RNA‐directed inhibition of hepatitis B virus replication

RNA interference (RNAi) is the process by which double‐stranded RNA directs sequence‐specific degradation of mRNA. In mammalian cells, RNAi can be triggered by 21‐nucleotide duplexes of short interfering RNA (siRNA). We examined effects of siRNA on hepatitis B virus (HBV) replication. Human hepatoma cells were transfected with HBV DNA and siRNA against HBV‐pregenome RNA. Transfection experiments demonstrated that the siRNA reduced the amount of HBV‐pregenome RNA and resulted in reduction of the levels of replicative intermediates and viral protein. Our results indicate that siRNA‐mediated gene silencing inhibits HBV replication through suppression of viral RNA, which may be useful as a potential therapeutic modality.

Interferon-|[alpha]| sensitizes human hepatoma cells to TRAIL-induced apoptosis through DR5 upregulation and NF-|[kappa]|B inactivation

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF superfamily, induces apoptosis in a variety of cancer cells with little or no effect on normal cells. Human hepatoma cells, however, are resistant to TRAIL-induced apoptosis. Since interferon-α (IFN-α) is capable of enhancing TNF-α-induced apoptosis in certain cancer cells, we evaluated the effect of IFN-α on TRAIL-induced apoptosis of human hepatoma cells. IFN-α pretreatment enhanced TRAIL-induced apoptosis of HuH-7 and Hep3B cells, in which IFN-α upregulated the expression of DR5, a death receptor of TRAIL, and downregulated the expression of survivin, which has an antiapoptotic function. In contrast, IFN-α did not enhance TRAIL-induced apoptosis of HepG2 cells, in which expression of DR5 and survivin was not affected by IFN-α. On the other hand, TRAIL activated NF-κB composed of RelA-p50 heterodimer, a key transcription factor regulating cell survival, in HuH-7 and HepG2 cells. However, IFN-α pretreatment repressed the TRAIL-mediated activation of NF-κB and decreased its transcriptional activity in HuH-7 but not in HepG2 cells. Moreover, IFN-α pretreatment clearly augmented TRAIL-mediated caspase-8 activation in HuH-7 cells. Our results suggest that IFN-α could sensitize certain human hepatoma cells to TRAIL-induced apoptosis by stimulating its death signaling and by repressing the survival function in these cells.

Association Between Liver Fibrosis and Insulin Sensitivity in Chronic Hepatitis C Patients

BACKGROUND:Several clinical studies have suggested a possible link between chronic hepatitis caused by hepatitis C virus (HCV) and the development of diabetes mellitus. We investigated the association between liver fibrosis and glucose intolerance in HCV-infected patients by measuring insulin sensitivity and β-cell function.METHOD:A total of 83 chronic HCV-infected patients were recruited into this study. We evaluated insulin sensitivity and β-cell function of all patients in a fasting state (homeostasis model assessment of insulin resistance [HOMA-R] and homeostasis model assessment of β-cell function [HOMA-β]) and after an oral load of 75 g glucose (whole-body insulin sensitivity index [WBISI] and Δ-insulin/Δ-glucose 30).RESULTS:In a multivariate analysis, severe fibrosis was the only independent factor associated with insulin resistance. There were significant differences in both HOMA-R (P = 0.0063) and WBISI (P = 0.0159) between patients with mild fibrosis (N = 34) and those with severe fibrosis (N = 49). Although HOMA-β was increased significantly in the subjects with severe fibrosis compared with those with mild fibrosis (P = 0.0169), Δ-insulin/Δ-glucose 30 showed no significant difference in stage of liver fibrosis, suggesting an uncertain association between liver fibrosis and β-cell function.CONCLUSION:Our findings suggest that the development of liver fibrosis is associated with insulin resistance in HCV-infected patients.

Association between nonalcoholic fatty liver, markers of obesity, and serum leptin level in young adults.

OBJECTIVES:The aim of the present study was to clarify the risk factors for nonalcoholic fatty liver in young adults.METHODS:One thousand two hundred two students, aged 18–21 yr, received matriculation health examinations, including measurements of body mass index and percent body fat and determination of serum levels of ALT at Nagasaki University in 1998. One hundred twenty-nine were found to have borderline or elevated levels of serum ALT, and 105 of the 129 students (75 men and 30 women) were subjected to further analysis for the presence of fatty liver using ultrasonography, by which both the degree of steatosis and the abdominal wall fat index (AFI) corresponding to the ratio of visceral to s.c. adipose tissue (V/S ratio) were evaluated, in addition to determination of the serum level of leptin.RESULTS:Of 105 students, 74 (70%) had fatty liver. The incidence of moderately to severely fatty liver was significantly higher in men than in women. In parameters related to obesity, the close correlation between body mass index and percent body fat was observed in both sexes. The serum level of leptin correlated well with percent body fat and AFI (V/S ratio) in women, whereas it did not correlate with AFI (V/S ratio) in men. Multiple logistic regression analysis indicated that AFI (V/S ratio) was the only independent risk factor for fatty liver in both sexes.CONCLUSIONS:These results suggest that visceral fat distribution is a key risk factor for nonalcoholic fatty liver in young adults.

Non-alcoholic steatohepatitis and hepatic steatosis in patients with adult onset growth hormone deficiency.

Adult onset growth hormone (GH) deficiency closely resembles syndrome X.1 Patients with syndrome X often suffer from obesity, dyslipidaemia, insulin resistance, and hypertension, and hepatic steatosis and non-alcoholic steatohepatitis (NASH) have also been characterised as symptoms of syndrome X.2,3 However, the relationship of GH deficiency to hepatic steatosis and NASH remains unclear. We looked for the presence of hepatic steatosis using computer tomography (CT) in a study of 18 patients with adult …

Significance of serum and hepatic microRNA-122 levels in patients with non-alcoholic fatty liver disease.

Non‐alcoholic fatty liver disease (NAFLD) is believed to be a type of metabolic syndrome. MicroRNA‐122 (miR‐122) is the most abundant microRNA in the liver and is an important factor for the metabolism of glucose and lipids. In the present study, we examined the correlation between the hepatic and serum miR‐122 expression levels and the clinicopathological factors of patients with NAFLD.

Perioperative synbiotic treatment to prevent infectious complications in patients after elective living donor liver transplantation: a prospective randomized study

BACKGROUND Although the effect of synbiotic therapy using prebiotics and probiotics has been reported in hepatobiliary surgery, there are no reports of the effect on elective living-donor liver transplantation (LDLT). METHODS Fifty adult patients undergoing LDLT between September 2005 and June 2009 were randomized into a group receiving 2 days of preoperative and 2 weeks of postoperative synbiotic therapy (Bifidobacterium breve, Lactobacillus casei, and galactooligosaccharides [the BLO group]) and a group without synbiotic therapy (the control group). Postoperative infectious complications were recorded as well as fecal microflora before and after LDLT in each group. RESULTS Only 1 systemic infection occurred in the BLO group (4%), whereas the control group showed 6 infectious complications (24%), with 3 cases of sepsis and 3 urinary tract infections with Enterococcus spp (P = .033 vs BLO group). No other type of complication showed any difference between the groups. CONCLUSIONS Infectious complications after elective LDLT significantly decreased with the perioperative administration of synbiotic therapy.

T helper type 17 immune response plays an indispensable role for development of iodine-induced autoimmune thyroiditis in nonobese diabetic-H2h4 mice.

T helper type 1(Th1)/Th2 paradigm has been expanded by discovery of a novel effector T cell (T(eff)) subset, Th17 cells, which produce a proinflammatory cytokine IL-17. Th17 cells have recently been shown to play a major role in numerous autoimmune diseases that had previously been thought to be Th1-dominant diseases. We here studied the significance of Th17 cells in iodine-induced autoimmune thyroiditis in nonobese diabetic-H2(h4) mice, a mouse model of Hashimotos thyroiditis in humans, which spontaneously develop antithyroglobulin autoantibodies and intrathyroidal lymphocyte infiltration when supplied with iodine in the drinking water. We observed increased numbers of Th1 and Th17 cells in spleen and accumulation of both types of T(eff) in the thyroid glands of iodine-fed wild-type mice, indicating that Th17 cells as well as Th1 cells constitute thyroid lesions. Furthermore, the incidence and severity of intrathyroidal lymphocyte infiltration, and the titers of antithyroglobulin autoantibodies were markedly reduced in iodine-treated IL-17(-/-) mice as compared with wild-type mice. Of interest, IL-17(+/-) mice showed an intermediate phenotype. Therefore, the present study, together with a previous report demonstrating the importance of Th1, not Th2, immune response for developing thyroiditis using mice deficient for interferon-gamma or IL-4, clearly indicates that both Th1 and Th17 cells are critical T(eff) subsets for the pathogenesis of spontaneous autoimmune thyroiditis in nonobese diabetic-H2(h4) mice.

Prognosis of patients with hepatocellular carcinoma after hepatic resection: Are elderly patients suitable for surgery?

The indication for hepatectomy is still controversial in elderly patients with hepatocellular carcinoma (HCC). We examined the clinicopathological features and survival of 188 HCC patients who underwent hepatectomy.

Antitumor function of microRNA-122 against hepatocellular carcinoma

MicroRNA-122 (miR-122), a highly abundant and liver-specific miRNA, acts as a tumor suppressor against hepatocellular carcinoma (HCC). Decreased expression of miR-122 in HCC is frequently observed and is associated with poor differentiation, larger tumor size, metastasis and invasion, and poor prognosis. Mutant mice with knockout (KO) of the miR-122 locus developed steatohepatitis due to increased triglyceride (TG) synthesis and decreased TG secretion from hepatocytes, and eventually developed HCC. Exogenic miR-122 introduction into miR-122 KO mice inhibited the development of HCC. Target genes of miR-122, including cyclin G1, a disintegrin and metalloprotease (ADAM)10, serum response factor, insulin-like growth factor-1 receptor, ADAM17, transcription factor CUTL1, the embryonic isoform of pyruvate kinase (Pkm2), Wnt1, pituitary tumor-transforming gene 1 binding factor, Cut-like homeobox 1, and c-myc, are involved in hepatocarcinogenesis, epithelial mesenchymal transition, and angiogenesis. MiR-122 expression is regulated by liver-enriched transcription factors such as hepatocyte nuclear factor (HNF)1α, HNF3β, HNF4α, HNF6, and CCAAT/enhancer-binding protein (C/EBP)α. A positive feedback loop exists between C/EBPα and miR-122 and between HNF6 and miR-122, whereas a negative feedback loop exists between c-myc and miR-122. Since cotreatment of 5-Aza-Cd and histone deacetylase inhibitor restored miR-122 expression in HCC cells, epigenetic modulation of miR-122 expression is involved in the suppression of miR-122 in HCC. Several experiments suggest that increasing miR-122 levels in HCC with or without antitumor agents may be a promising strategy for HCC treatment.