Minoru Itou

Clearance of HCV improves insulin resistance, beta-cell function, and hepatic expression of insulin receptor substrate 1 and 2.

OBJECTIVES:Hepatitis C virus (HCV) infection is linked to greater insulin resistance. Although HCV itself is a candidate for the development of insulin resistance, the effects of antiviral treatment on impaired glucose metabolism remain unclear. The aim of this study is to examine the effects of clearance of HCV on insulin resistance, beta-cell function, and hepatic expression of insulin receptor substrate (IRS)1/2, central molecules for insulin signaling.METHODS:We analyzed 89 biopsy-proven patients with chronic HCV infection. Patients received interferon-α or interferon-α plus ribavirin for 6 months and were classified into three groups at 6 months after the conclusion of antiviral therapy according to their response to antiviral therapy: sustained responders (N = 29), relapsers (N = 12), and nonresponders (N = 48). Insulin resistance and beta-cell function were assessed by the homeostasis model assessment method (HOMA-IR and HOMA-%B, respectively). Hepatic expression of IRS1/2 was evaluated by immunoblotting and immunostaining in 14 sustained responders.RESULTS:In nonresponders and relapsers, there were no significant changes in HOMA-IR and HOMA-%B values after antiviral therapy. On the other hand, in sustained responders, HOMA-IR values significantly decreased to 1.7 ± 0.8 from 3.1 ± 1.1 (P < 0.05) after antiviral therapy. Similarly, HOMA-%B values significantly decreased to 90.6 ± 10.0 from 113.7 ± 15.3 (P < 0.05). Immunoblotting showed a threefold increase in IRS1/2 expression after clearance of HCV. Immunostaining revealed that greater IRS1/2 expression was seen in hepatocytes.CONCLUSIONS:We showed that clearance of HCV improves insulin resistance, beta-cell function, and hepatic IRS1/2 expression.

Dipeptidyl peptidase-4: A key player in chronic liver disease

Dipeptidyl peptidase-4 (DPP-4) is a membrane-associated peptidase, also known as CD26. DPP-4 has widespread organ distribution throughout the body and exerts pleiotropic effects via its peptidase activity. A representative target peptide is glucagon-like peptide-1, and inactivation of glucagon-like peptide-1 results in the development of glucose intolerance/diabetes mellitus and hepatic steatosis. In addition to its peptidase activity, DPP-4 is known to be associated with immune stimulation, binding to and degradation of extracellular matrix, resistance to anti-cancer agents, and lipid accumulation. The liver expresses DPP-4 to a high degree, and recent accumulating data suggest that DPP-4 is involved in the development of various chronic liver diseases such as hepatitis C virus infection, non-alcoholic fatty liver disease, and hepatocellular carcinoma. Furthermore, DPP-4 occurs in hepatic stem cells and plays a crucial role in hepatic regeneration. In this review, we described the tissue distribution and various biological effects of DPP-4. Then, we discussed the impact of DPP-4 in chronic liver disease and the possible therapeutic effects of a DPP-4 inhibitor.

Insulin resistance and chronic liver disease.

Increased insulin resistance is frequently associated with chronic liver disease and is a pathophysiological feature of hepatogenous diabetes. Distinctive factors including hepatic parenchymal cell damage, portal-systemic shunting and hepatitis C virus are responsible for the development of hepatogenous insulin resistance/diabetes. Although it remains unclear whether insulin secretion from pancreatic beta cells is impaired as it is in type 2 diabetes, retinopathic and cardiovascular risk is low and major causes of death in cirrhotic patients with diabetes are liver failure, hepatocellular carcinoma and gastrointestinal hemorrhage. Hemoglobin A1c is an inaccurate marker for the assessment and management of hepatogenous diabetes. Moreover, exogenous insulin or sulfonylureas may be harmful because these agents may promote hepatocarcinogenesis. Thus, pathogenesis, cause of death, assessment and therapeutic strategy for hepatogenous insulin resistance/diabetes differ from those for lifestyle-related type 2 diabetes. In this article, we review features of insulin resistance in relationship to chronic liver disease. We also discuss the impact of anti-diabetic agents on interferon treatment and hepatocarcinogenesis.

Phase I clinical study of a peptide vaccination for hepatitis C virus‐infected patients with different human leukocyte antigen‐class I‐A alleles

Hepatitis C virus (HCV) infection has a high risk of liver cirrhosis and hepatocellular carcinoma at later stages. We recently identified a peptide derived from the HCV core protein capable of inducing both cellular and humoral responses to nearly all HCV‐positive patients in Japan with different human leukocyte antigen (HLA)‐class I‐A alleles. To assess the safety and immune responses to this novel peptide, we conducted a phase I dose‐escalation study of the vaccination for 26 HCV‐positive patients who were either non‐responders to the interferon‐based therapy (n = 23) or refused it (n = 3). The regimen was well tolerated, with no severe vaccine‐related toxicity. Twenty‐five and 22 patients completed the first and second cycle vaccination (6 and 12 vaccine injections), respectively. After a series of six vaccine injections, peptide‐specific CTL activity was augmented in peripheral blood mononuclear cells from 15 of 25 patient samples, with an expected optimal dose of 1 mg peptide. After 12 vaccine injections, peptide‐specific IgG production was augmented in plasma from the majority of patients (15 of 22 patients) tested, but not in a dose‐dependent fashion. There were two HCV RNA responders with >1 log declines. Among patients whose pre‐vaccination levels of alanine aminotransferase and alpha feto‐protein exceeded the normal ranges, a <30% decrease was found in 7 of 24 and three of six patients, respectively. Because of its tolerability and higher rate of immune boosting, this protocol is recommended for a phase II study to investigate its clinical efficacy. (Cancer Sci 2009; 100: 1935–1942)

Altered expression of glucagon‐like peptide‐1 and dipeptidyl peptidase IV in patients with HCV‐related glucose intolerance

Background and Aim:  The pathogenesis of hepatitis C virus (HCV)‐associated glucose intolerance remains unclear. Glucagon‐like peptide‐1 (GLP‐1), a gut hormone, synthesizes hepatic glycogen and is inactivated by dipeptidyl peptidase IV (DPPIV). The aims of this study were to investigate the alterations in the expression of GLP‐1 and DPPIV in HCV‐associated glucose intolerance.

Branched‐chain amino acids improve insulin resistance in patients with hepatitis C virus‐related liver disease: report of two cases

Hepatitis C virus (HCV) infection causes insulin resistance. Because increased insulin resistance is a risk factor for development of hepatocellular carcinoma and reduced long‐term survival, insulin resistance is a therapeutic target in patients with HCV infection. Branched‐chain amino acids (BCAAs) are not only structural constituents of proteins but they are also considered as regulators of insulin signalling. We first describe two cases suggesting that administration of BCAAs improves insulin resistance associated with HCV‐related liver disease. Although there were no changes in body weight, plasma glucose concentration and haemoglobin A1c (HbA1c) value were decreased. Moreover, BCAAs caused a decrease in both fasting insulin concentration and the value of homeostasis model assessment for insulin resistance. Thus, BCAAs are a potential therapeutic agent for improving insulin resistance in patients with HCV‐related liver disease.

Dipeptidyl Peptidase IV Inhibitor Improves Insulin Resistance and Steatosis in a Refractory Nonalcoholic Fatty Liver Disease Patient: A Case Report

A 67-year-old Asian woman was referred to Kurume University Hospital due to abnormal liver function tests. She was diagnosed with nonalcoholic fatty liver disease (NAFLD). NAFLD was treated by diet therapy with medication of metformin and pioglitazone; however, NAFLD did not improve. Subsequently, the patient was administered sitagliptin. Although her energy intake and physical activity did not change, her hemoglobin A1c level was decreased from 7.8 to 6.4% 3 months after treatment. Moreover, her serum insulin level and homeostasis model assessment-insulin resistance value were also improved, as was the severity of hepatic steatosis. These findings indicate that sitagliptin may improve insulin resistance and steatosis in patients with refractory NAFLD.

Nutritional assessments for ordinary medical care in patients with chronic liver disease.

Aim:  In patients with chronic liver disease who are at risk of malnutrition, simple and useful assessments for nutritional status should be established for ordinary medical care. The prognostic nutritional index (PNI) and controlling nutritional status (CONUT) are simple assessments constructed of only two or three laboratory data. We aimed to describe the potential of PNI and CONUT as a nutritional assessment tool in patients with chronic liver disease.

Lipid profile is associated with the incidence of cognitive dysfunction in viral cirrhotic patients: A data-mining analysis.

Aim:  Cognitive dysfunction (CD) is frequently observed in cirrhotic patients. However, the biochemical profiles associated with CD remain unclear. We investigated the biochemical profiles associated with the incidence of CD in cirrhotic patients by using multivariate analyses, including a decision‐tree algorithm.

Pigment Epithelium-Derived Factor Inhibits Lysosomal Degradation of Bcl-xL and Apoptosis in HepG2 cells

Pigment epithelium-derived factor (PEDF) has several biological actions on tumor cells, but its effects are cell-type dependent. The aim of this study was to examine the pathophysiological role of PEDF in hepatocellular carcinoma (HCC). PEDF expression was examined in various hepatoma cell lines and human HCC tissues, and was seen in various hepatoma cell lines including HepG2 cells. In human HCC tissues, PEDF expression was higher than in adjacent non-HCC tissues. In addition, serum PEDF levels were higher in HCC patients than in non-HCC patients, and curative treatment of HCC caused significant reductions in serum PEDF levels compared with pretreatment levels. In vitro experiments, camptothecin (CPT) was used to induce apoptosis and the effect of PEDF was investigated by knockdown of the PEDF gene in CPT-treated HepG2 cells. Knockdown of the PEDF gene enhanced CPT-induced apoptosis, simultaneously down-regulating Bcl-xL expression in HepG2 cells. Expression of apoptosis-related molecules and effects of bafilomycin A1 on CPT-induced apoptosis were also examined in PEDF gene knockdown HepG2 cells. Treatment with bafilomycin A1 suppressed CPT-induced decreases in Bcl-xL expression and increases in apoptosis in PEDF gene knockdown HepG2 cells. PEDF may, therefore, exert anti-apoptotic effects through inhibition of lysosomal degradation of Bcl-xL in CPT-treated HepG2 cells.