Adiponectin: a new independent predictor of liver steatosis and response to IFN-alpha treatment in chronic hepatitis C

Roles of Adipokines in Digestive Diseases: Markers of Inflammation, Metabolic Alteration and Disease Progression

Adipose tissue is a highly dynamic endocrine tissue and constitutes a central node in the interorgan crosstalk network through adipokines, which cause pleiotropic effects, including the modulation of angiogenesis, metabolism, and inflammation. Specifically, digestive cancers grow anatomically near adipose tissue. During their interaction with cancer cells, adipocytes are reprogrammed into cancer-associated adipocytes and secrete adipokines to affect tumor cells. Moreover, the liver is the central metabolic hub. Adipose tissue and the liver cooperatively regulate whole-body energy homeostasis via adipokines. Obesity, the excessive accumulation of adipose tissue due to hyperplasia and hypertrophy, is currently considered a global epidemic and is related to low-grade systemic inflammation characterized by altered adipokine regulation. Obesity-related digestive diseases, including gastroesophageal reflux disease, Barrett's esophagus, esophageal cancer, colon polyps and cancer, non-alcoholic fatty liver disease, viral hepatitis-related diseases, cholelithiasis, gallbladder cancer, cholangiocarcinoma, pancreatic cancer, and diabetes, might cause specific alterations in adipokine profiles. These patterns and associated bases potentially contribute to the identification of prognostic biomarkers and therapeutic approaches for the associated digestive diseases. This review highlights important findings about altered adipokine profiles relevant to digestive diseases, including hepatic, pancreatic, gastrointestinal, and biliary tract diseases, with a perspective on clinical implications and mechanistic explorations.

Systematic review: chronic viral hepatitis and metabolic derangement

BACKGROUND

The liver has a critical role in the metabolism of glucose and lipids. Chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection leads to a spectrum of liver disease including chronic hepatitis, cirrhosis and hepatocellular carcinoma. Metabolic syndrome (MetS) has a rising incidence owing to an epidemic of type 2 diabetes mellitus (T2DM) and obesity. Non-alcoholic fatty liver disease is a liver manifestation of MetS and has become the most common cause of chronic liver disease worldwide.

AIM

To summarise the interplay among hepatitis viruses, MetS and its components.

METHODS

We searched the literature about HBV, HCV infection, MetS, fatty liver and its components from PubMed.

RESULTS

With respect to the viral replication cycle, lipids are important mediators between viral entry and hepatocyte in HCV infection, but not in HBV infection. Thus, HCV infection is inversely associated with hyperlipidaemia and lipid rebound occurs following sustained viral response induced by interferon-based therapy or direct antiviral agents. In addition, HCV infection is positively associated with insulin resistance, hepatic steatosis, MetS and the risk of T2DM and atherosclerosis. In contrast, HBV infection may protect infected subjects from the development of MetS and hepatic steatosis. Accumulating evidence suggests that HBV infection is inversely associated with lipid metabolism, and exhibits no conclusive association with insulin resistance or the risk of T2DM and arteriosclerosis.

CONCLUSIONS

In patients with viral hepatitis and concurrent metabolic diseases, a multidisciplinary approach should be given rather than simply antiviral treatment.

Inflammatory and cardiovascular diseases biomarkers in chronic hepatitis C virus infection: A review

Hepatitis C virus (HCV) infects 180 million people worldwide and over 4 million people in the United States. HCV infection is a major cause of chronic liver disease and is recognized as a risk factor for clinical cardiovascular disease (CVD). Many studies have shown increased prevalence of cardiac and inflammatory biomarkers in patients with chronic HCV infection (CHC), and though these markers may be used to risk stratify people for cardiac disease in the general population their role in the HCV population is unknown. Patients with CHC have elevated cardiac and inflammatory biomarkers compared to noninfected controls which may play a role in CVD risk stratification. We undertook a systematic review of inflammatory and cardiac biomarkers in people with HCV infection with a focus on the effect of CHC on serum levels of these markers and their utility as predictors of CVD in this population. Medline, EMBASE, and Cochrane databases were searched for relevant articles until June 2019. A total of 2430 results were reviewed with 115 studies included. Our review revealed that HCV infection significantly alters serum levels of markers of inflammation, endothelial function, and cardiac dysfunction prior to HCV treatment, and some of which may change in response to HCV therapy. Current risk stratification tools for development of CVD in the general population may not account for the increased inflammatory markers that appear to be elevated among HCV‐infected patients contributing to increased CVD risk.

Therapeutic Potential of Plasma Proteins Derived from Umbilical Cord Blood for Acute Liver Failure

There are very limited clinically viable treatment options for acute liver failure, a life-threatening condition that rapidly progresses to loss of liver function. In this study, we aim to evaluate the therapeutic potential of UCBP for acute liver failure induced in a rat model by D-galactosamine (GalN). F344 rats were randomly divided into two groups (control and UCBP-treated) after GalN injection. The therapeutic effects of UCBP were evaluated based on survival rate, H&E staining, TUNEL, PCNA staining, and in vivo BrdU labeling. Hepatocyte proliferation and the therapeutic mechanisms of UCBP were examined with BrdU and Western blot assay in vitro. The survival rate in the UCBP-treated group was found to be increased compared to the control group (85 vs 55%, P = 0.029). UCBP treatment significantly decreased apoptosis and increased cell proliferation. These effects may be secondary to specific bioactive molecules in UCBP. In vitro experiments revealed that adiponectin is one of the key biologically active components of UCBP in facilitating this result and promoting hepatocyte proliferation. Furthermore, this effect is mediated by p38/ERK mitogen-activated protein kinase (MAPK) signaling pathways. Therefore, this uncomplicated and clinically accessible approach may serve as effective bridge therapy for acute liver failure.

The evolving relationship between adiponectin and insulin sensitivity in hepatitis C patients during viral clearance

BACKGROUND

The evolution of the relationship between adiponectin and insulin sensitivity in hepatitis C virus (HCV) patients during viral clearance is unclear and warrants investigation.

METHODS

A prospective study including 747 consecutive chronic hepatitis C (CHC) patients, of whom 546 had completed a course of anti-HCV therapy and underwent pre-, peri- and post-therapy surveys for anthropomorphic, viral, metabolic and hepatic profiles and adiponectin levels, was conducted in a tertiary care center.

RESULTS

Multivariate analyses indicated associations of sex, triglyceride levels and hepatic steatosis with adiponectin levels and of triglyceride levels and interferon λ3 (IFNL3) genotype with homeostasis model assessment-estimated insulin resistance (HOMA-IR) levels before anti-HCV therapy. In patients with a sustained virological response (SVR; n = 455), at 24 weeks post-therapy, sex, BMI, aspartate aminotransferase to platelet ratio index (APRI), HOMA-IR and steatosis were associated with adiponectin levels, and IFNL3 genotype was associated with HOMA-IR levels. GEE analysis demonstrated that SVR affected longitudinal trends in adiponectin levels. Compared with pre-therapy levels, adiponectin and APRI levels decreased 24 weeks post-therapy in SVR patients, regardless of baseline insulin resistance (IR). However, HOMA-IR levels decreased in SVR patients with baseline IR but increased in those without baseline IR. Compared with controls, immunohistochemical studies showed that pre-therapy CHC patients had higher hepatic adiponectin expression associated with hepatic fibrosis.

CONCLUSIONS

During HCV infection, adiponectin may affect insulin sensitivity through triglycerides. After viral clearance, adiponectin levels were directly associated with insulin sensitivity and decreased upon improved hepatic fibrosis; with a link to the IFNL3 genotype, insulin sensitivity improved only in patients with baseline IR.

Metabolic alterations and hepatitis C: From bench to bedside

In addition to causing cirrhosis and hepatocellular carcinoma, hepatitis C virus (HCV) is thought to cause hypolipidemia, hepatic steatosis, insulin resistance, metabolic syndrome, and diabetes. The viral life cycle of HCV depends on cholesterol metabolism in host cells. HCV core protein and nonstructural protein 5A perturb crucial lipid and glucose pathways, such as the sterol regulatory element-binding protein pathway and the protein kinase B/mammalian target of rapamycin/S6 kinase 1 pathway. Although several lines of transgenic mice expressing core or full HCV proteins exhibit hepatic steatosis and/or dyslipidemia, whether they completely reflect the metabolic alterations in humans with HCV infection remains unknown. Many cross-sectional studies have demonstrated increased prevalences of metabolic alterations and cardiovascular events in patients with chronic hepatitis C (CHC); however, conflicting results exist, primarily due to unavoidable individual variations. Utilizing anti-HCV therapy, most longitudinal cohort studies of CHC patients have demonstrated the favorable effects of viral clearance in attenuating metabolic alterations and cardiovascular risks. To determine the risks of HCV-associated metabolic alterations and associated complications in patients with CHC, it is necessary to adjust for crucial confounders, such as HCV genotype and host baseline glucose metabolism, for a long follow-up period after anti-HCV treatment. Adipose tissue is an important endocrine organ due to its release of adipocytokines, which regulate lipid and glucose metabolism. However, most data on HCV infection and adipocytokine alteration are inconclusive. A comprehensive overview of HCV-associated metabolic and adipocytokine alterations, from bench to bedside, is presented in this topic highlight.

Adiponectin: A biomarker for chronic hepatitis C?

Adiponectin, a hormone primarily synthesized and secreted by adipose tissue, plays a pivotal role in lipid metabolism. Chronic hepatitis C (CHC) infection is characterized by disordered lipid metabolism, which may potentially evolve into steatosis over a period of time. A growing body of evidence appears to link decreased adiponectin plasma levels with severe CHC-related steatosis, which suggests a potential role of this adipokine as a diagnostic and therapeutic target for clinical application. In this review, we have attempted to summarize the current status of adiponectin research in the context of CHC, concentrating predominantly on its roles in CHC, and its potential relevance as a biomarker for CHC.

Increased circulating adiponectin in males with chronic HCV hepatitis

BACKGROUND

Increased levels of adiponectin, a major adipokine with insulin sensitizing properties showing a strong sexual dimorphism, have been reported in individuals with chronic HCV infection (CHC), but data are limited by small samples and lack of control for the genetic background and hepatic fibrosis. The aim of this study was to compare adiponectin levels between CHC patients and accurately matched controls.

METHODS

We considered 184 CHC patients, matched (1:1) for age, gender, body mass index, and Adiponectin genotype (ADIPOQ) with healthy individuals. To control for the severity of liver disease, a second control group consisting of 95 patients with histological nonalcoholic fatty liver disease (NAFLD) further matched (1:1) for severe fibrosis was exploited. ADIPOQ genotype was evaluated by Taqman assays, serum adiponectin measured by ELISA.

RESULTS

Serum adiponectin was higher in CHC patients than in healthy individuals (9.0±5.0 μg/ml vs. 7.3±4.0 μg/ml; p=0.001; adjusted estimate +1.8, 1.7-2.9; p=0.001), and than in NAFLD patients (8.3±4.5 μg/ml vs. 6.0±4.2 μg/ml; p<0.001; adjusted estimate +0.8, 0.2-1.4, p=0.006). After stratification for sex, serum adiponectin was higher in males with CHC than in healthy individuals and NAFLD patients (p<0.005 for both), whereas the difference was not significant in females.

CONCLUSIONS

CHC is associated with increased serum adiponectin independently of age, body mass, diabetes, ADIPOQ genotype, and of severe liver fibrosis, particularly in men.

Involvement of resveratrol in crosstalk between adipokine adiponectin and hepatokine fetuin-A in vivo and in vitro

Metabolic homeostasis is maintained by the coordinated regulation of several physiological processes and organ crosstalk. Especially, the interaction between adipose tissue and liver is critical for the regulation of glucose and lipid metabolism. This study investigated the involvement of resveratrol (RSV) in the crosstalk between adipokine adiponectin and hepatokine fetuin-A. Adipocytes-hepatocytes co-culture system and a high-fat (HF) diet-induced obesity (DIO) mouse model were utilized. Protein levels of adiponectin and fetuin-A were analyzed in adipocytes and hepatocytes with the knockdown of adiponectin and fetuin-A, respectively. After six weeks of the HF diet treatment, RSV was delivered via an osmotic pump for four weeks. The experimental groups were lean control fed with a standard diet, HF diet-induced obese control and HF_RSV (8 mg/kg/day). After 4 weeks of each treatment, blood and tissues were collected, and the levels of adiponectin and fetuin-A were analyzed. RNA interference during co-culture of adipocytes and hepatocytes demonstrated the existence of crosstalk between adiponectin and fetuin-A. The four-week RSV treatment resulted in increased serum adiponectin and decreased serum fetuin-A in diet-induced obesity mice. The serum levels of adiponectin and fetuin-A were inversely related. In epididymal fat depots, RSV increased adiponectin, peroxisome proliferator-activated receptor (PPAR) alpha, PPAR gamma, sirtuin1 and AMP-activated protein kinase (AMPK). RSV lowered fetuin-A and NF-κB, and increased liver AMPK. These results demonstrate the crosstalk between adiponectin and fetuin-A, and suggest that RSV may be involved in adipose tissue and liver crosstalk through the interaction between adiponectin and fetuin-A.

Correlates of adiponectin in hepatitis C-infected children: the importance of body mass index

OBJECTIVES

Adiponectin is a regulator of cytokines that, in turn, play a vital role in inflammatory and immune responses. Adiponectin is therefore likely to have a contributory role in hepatitis C virus (HCV) infection. We sought to characterize adiponectin levels and examine correlates in a pediatric HCV-infected cohort.

METHODS

We performed a cross-sectional study in children (5-17 years of age, n = 86) in the Pediatric Study of Hepatitis C (PEDS-C) trial. Adiponectin levels were univariately correlated with patient demographics, anthropometrics, and viral and histological measures. Multivariate regression models were used to identify the unique (ie, nonconfounded) associations with adiponectin concentrations.

RESULTS

Body mass index (BMI) had the highest univariate inverse correlation with log(e) adiponectin (r = -0.5, P < 0.0001). In multivariate analysis, BMI remained inversely correlated with log(e) adiponectin after accounting for age and route of HCV transmission (r = -0.38, P = 0.0003). Steatosis and fibrosis were inversely related to log(e) adiponectin in univariate analysis, but these associations were not statistically significant after multivariate adjustments (P ≥ 0.1827).

CONCLUSIONS

High BMI among HCV-infected children is associated with lower adiponectin levels. Practitioners should be cognizant of the possible risks of low adiponectin when managing HCV-infected children who are overweight. Further studies are indicated to determine the impact of having low adiponectin on HCV infection in youth.

Serum Adiponectin, Vitamin D, and Alpha-Fetoprotein in Children with Chronic Hepatitis C: Can They Predict Treatment Response?

Background & Aims. The currently available treatment for chronic hepatitis C (CHC) in children is costly and with much toxicity. So, predicting the likelihood of response before starting therapy is important. Methods. Serum adiponectin, vitamin D, and alpha-fetoprotein (AFP) were measured before starting pegylated-interferon/ribavirin therapy for 50 children with CHC. Another 21 healthy children were recruited as controls. Results. Serum adiponectin, vitamin D, and AFP were higher in the CHC group than healthy controls (p < 0.0001, p = 0.071, and p = 0.87, resp.). In univariate analysis, serum adiponectin was significantly higher in responders than nonresponders (p < 0.0001) and at a cutoff value ≥8.04 ng/mL it can predict treatment response by 77.8% sensitivity and 92.9% specificity, while both AFP and viremia were significantly lower in responders than nonresponders, p < 0.0001 and p = 0.0003, respectively, and at cutoff values ≤3.265 ng/mL and ≤235,384 IU/mL, respectively, they can predict treatment response with a sensitivity of 83.3% for both and specificity of 85.7% and 78.6%, respectively. In multivariate analysis, adiponectin was found to be the only independent predictor of treatment response (p = 0.044). Conclusions. The pretreatment serum level of adiponectin can predict the likelihood of treatment response, thus avoiding toxicities for those unlikely to respond to therapy.

Inverse Levels of Adiponectin in Type 1 and Type 2 Diabetes Are in Accordance with the State of Albuminuria

Aims. To investigate the behaviour of adiponectin (ApN) in patients with type 1 and type 2 diabetic nephropathy. Methods. ApN and inflammatory and other markers of the metabolic syndrome were compared across diabetes types, albumin excretion rate (AER), and creatinine clearance (CrCl) categories in 219 type 1 and type 2 diabetic patients. Results. Significant differences among ApN levels according to AER were found in both types of diabetes (F = 8.45, df = 2, P < 0.001). With the progression of albuminuria, ApN increased in type 1 and decreased in type 2 diabetes. Patients with decreased CrCl had higher ApN levels than those with normal CrCl in either type of diabetes (F = 12.7, df = 1, P < 0.001). The best model for ApN (R (2) = 0.9002) obtained from stepwise regression in type 1 diabetes included CrCl, BMI, WBC, CRP, and age, while in type 2 diabetes (R (2) = 0.2882) it included ppPG, LDL, and UA. Conclusion. ApN behaved differently in relation to albuminuria, increasing with its progression in type 1 diabetes and decreasing in type 2 diabetes. It was however increased in the subgroups with decreased CrCl in both types of diabetes. Albuminuria seems to be more important than renal insufficiency in the definition of ApN levels in type 1 and type 2 diabetes.

Variations of serum levels of adiponectin and resistin in chronic viral hepatitis

BACKGROUND AND AIMS

Several studies investigated the possible role of adipokines during chronic viral hepatitis, not producing defined results neither clearly establishing their behavior in course of anti-viral treatment. Our study evaluated blood concentrations of adiponectin and resistin in patients with chronic hepatitis C (CHC), B (CHB), and D (CHD) receiving anti-viral treatment, at baseline and after therapy.

METHODS

We examined 122 subjects, divided into two groups: 64 patients with chronic hepatitis C virus (HCV) infection (38 males and 26 females, mean age 47.25 yr) and 58 patients including 39 ones with chronic hepatitis B virus (HBV) infection (26 males and 13 females, mean age 48.46 yr) and 19 ones with chronic HBV-hepatitis D virus (HDV) infection (15 males and 4 females, mean age 45.79 yr). Serum levels of adiponectin and resistin were assayed by enzyme-linked immunosorbent assay.

RESULTS

In the group of CHC patients we observed a significant decrease in resistin after therapy (p=0.006), while not a significant increase in adiponectin after treatment (p=0.32). Evaluation of changes in adiponectin and resistin levels after anti-viral treatment, both in responders and non-responders, revealed no significant variations. In the group of HBV+ and HBV-HDV+ patients, we found a decrease in resistin after therapy (p=0.0016) and a not significant reduction in adiponectin after treatment (p=0.13). Furthermore, we noticed a significant reduction of resistin (p=0.006) in the sub-group of responders.

CONCLUSIONS

Our data suggested the possible marker role of adiponectin and resistin in the inflammatory process in course of chronic viral hepatitis.

Adipokines as mediators of endothelial function and atherosclerosis

For many decades, adipose tissue was considered as an inactive body compartment that was only used as an energy store. During the recent years, an increasing amount of data has revealed that adipose tissue is a major endocrine and paracrine organ producing numerous enzymes, hormones and growth factors which are collectively termed as adipokines. Several experimental and clinical studies showed that adipokines modulate insulin sensitivity and have an influence on glucose/fat metabolism and obesity. Apart from these properties, recent research revealed several direct actions of adipokines on endothelial function, vascular homeostasis and atherogenesis which are independent of their effects on glucose and fat metabolism. The present review focuses on the direct effects of adipokines on vascular/endothelial function and atherosclerosis and summarizes the experimental and clinical data which suggest a role for these molecules as potential diagnostic and prognostic cardiovascular markers as well as potential therapeutic target to reduce cardiovascular risk.

Adiponectin: a key playmaker adipocytokine in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and can progress to cirrhosis, liver failure, and hepatocellular carcinoma. In the last two decades, the prevalence of NAFLD has been growing in most developed countries, mainly as a consequence of its close association with obesity and diabetes mellitus. The exact pathogenesis of NAFLD and especially the mechanisms leading to disease progression have not been completely understood. Adipocytes produce and secrete several bioactive substances known as adipocytokines which are implicated in the pathogenesis of the disease. Among them, adiponectin is an insulin-sensitizing adipocytokine possessing multiple beneficial effects on obesity-related medical complication. This review focuses on the role of adiponectin in NAFLD pathogenesis and its potential use as a diagnostic tool but also as therapeutic target for NAFLD management.

Sex hormones and HCV: an unresolved mystery

The biological differences between males and females advocate the ultimate need for gender-specific medicine. The variation in response to viral infection as well as therapy among different genders makes it very intriguing to reveal the responsible factors for causing this discrepancy. HCV is one of the most noxious infectious diseases, however the impact of gender on the response to HCV has received negligible attention in the literature. The controversial studies concerning the effect of gender on the outcome of interferon-based therapy urge a need to judge the gender discrepancy in host factors responsible for both interferon release and action. The main aim of this review is to disentangle the interplay between sex hormones and several viral and host factors responsible for viral clearance in an attempt to clarify the role of gender in modulating the response to HCV as well as interferon-based therapy.

Hyperuricaemia: another metabolic feature affecting the severity of chronic hepatitis because of HCV infection

BACKGROUND

Several works observed a link between uric acid serum levels and clinical and histological features of nonalcoholic fatty liver disease. An association between chronic hepatitis C (CHC) and uric acid levels has been poorly investigated.

AIMS

To assess the potential association between uric acid serum levels and both histological features of liver damage and sustained virological response (SVR) in a homogeneous cohort of CHC patients.

METHODS

Consecutive biopsy-proven CHC patients were included. Hyperuricaemia was diagnosed with uric acid serum levels >7 mg/dl in men, and >6 mg/dl in women. Patients underwent therapy with pegylated interferon plus ribavirin.

RESULTS

Hyperuricaemia, observed in 7.5% of patients, was associated with low density lipoprotein cholesterol (OR 1.015, 95% CI 1.004-1.026, P = 0.008), arterial hypertension (OR 3.024, 95% CI 1.290-7.088, P = 0.01), estimated glomerular filtration rate (OR 0.942, 95% CI 0.919-0.965, P < 0.001) and severity of steatosis (OR 3.176, 95% CI 1.828-5.517, P < 0.001) by multivariate logistic regression analysis. The following features were independently linked to the severity of liver steatosis (<5% vs. ≥5% to <30% vs. ≥30%) using ordinal regression analysis: age (OR 1.027, 95% CI 1.011-1.044, P = 0.01), body mass index (OR 1.088, 95% CI 1.039-1.138, P < 0.001), triglycerides (OR 1.005, 95% CI 1.001-1.009, P = 0.02), homeostasis model assessment (OR 1.095, 95% CI 1.014-1.184, P = 0.02), hyperuricaemia (OR 2.751, 95% CI 1.423-5.322, P = 0.003), hepatitis C virus genotype 3 (OR 4.567, 95% CI 1.515-13.763, P = 0.007) and severe necroinflammatory activity (OR 1.584, 95% CI 1.067-2.349, P = 0.02). No independent association was found among uric acid levels and necroinflammatory activity, fibrosis and SVR.

CONCLUSIONS

In CHC patients, hyperuricaemia was independently associated with severity of steatosis, representing, in this setting, via steatosis induction, an indirect factor affecting both liver damage and poor response to therapy, and thus a novel potential therapeutic target in CHC management.

Chronic hepatitis C genotype 1 patients with insulin resistance treated with pioglitazone and peginterferon alpha-2a plus ribavirin

Patients with chronic hepatitis C and insulin resistance are less likely to respond to anti-hepatitis C virus (HCV) therapy and are at risk for more rapid fibrosis progression. Coadministration of pioglitazone with peginterferon/ribavirin improves insulin sensitivity and increases virologic response rates in insulin-resistant HCV genotype 4 patients, but it is unclear whether this finding applies to genotype 1 patients. For this reason we randomized treatment-naive HCV genotype 1 patients with insulin resistance to receive either standard care (peginterferon alpha-2a plus ribavirin for 48 weeks, n = 73) or pioglitazone 30-45 mg/day plus standard care (n = 77) in an open-label multicenter trial. Patients randomized to pioglitazone received the drug during a 16-week run-in phase, the 48-week standard-care phase, and the 24-week untreated follow-up phase. Pioglitazone treatment improved hemoglobin A1c (HbA1c), plasma glucose, insulin levels, and homeostasis model assessment of insulin resistance score and increased serum adiponectin levels during the 16-week run-in phase and maintained these improvements during the standard-care phase. However, we observed no statistically significant difference between the two groups in the primary efficacy endpoint, the decrease from baseline to Week 12 of peginterferon alpha-2a/ribavirin treatment in mean log(10) HCV RNA titer (-3.5 ± 1.71 and -3.7 ± 1.62 IU/mL in the pioglitazone and standard-care groups, respectively, Δ = 0.21 IU/mL, P = 0.4394).

CONCLUSION

Treatment with pioglitazone before and during treatment with peginterferon alpha-2a plus ribavirin improved several indices of glycemic control in patients with chronic hepatitis C and insulin resistance, but did not improve virologic response rates compared with peginterferon alpha-2a plus ribavirin alone.

HCV core-induced nonobese hepatic steatosis is associated with hypoadiponectinemia and is ameliorated by adiponectin administration

Obesity-related hepatic steatosis is commonly associated with central fat accumulation and alterations in adipocytokine secretion; however, the connection between nonobese hepatic steatosis and adipocytokines remains unclear. We aim to investigate this connection using an animal model of conditional hepatitis C virus (HCV) core-transgenic mice. Double transgenic mice (DTM) with doxycycline (dox)-regulated hepatic overexpression of the HCV core protein were fed standard rodent chow ad libitum following 1 month of a dox-rich diet. The mice exhibited nonobese hepatic steatosis at 2 months of age. The levels of leptin and adiponectin were assessed in 2-month-old DTM (i.e., HCV core-tetracycline transactivator (tTA)) and single transgenic mice (STM; i.e., tTA). The total fat mass and the body fat distribution of the mice were evaluated using dual-energy X-ray absorptiometry (DEXA) and magnetic resonance imaging (MRI). Microarray analyses and quantitative real-time PCR were conducted using RNA obtained from the visceral fat of paired DTM and STM. Adiponectin was administered intraperitoneally to the 2-month-old DTM. No significant differences of the various fat components were noted between the DTM and STM. Leptin mRNA was downregulated in the visceral fat of DTM (P = 0.011), and serum adiponectin protein levels were reduced in the DTM compared with those in the STM (P = 0.035). Adiponectin treatment also significantly ameliorated hepatic steatosis in the DTM compared to the controls (P = 0.024). In conclusion, HCV core-induced nonobese hepatic steatosis is associated with downregulation of the leptin gene in visceral fat and concurrent hypoadiponectinemia; however, these effects may be ameliorated by adiponectin treatment.

Steatosis is the predictor of relapse in HCV genotype 3- but not 2-infected patients treated with 12 weeks of pegylated interferon-α-2a plus ribavirin and RVR

HCV genotypes 2- or 3-infected patients with a rapid virological response (RVR) to therapy with pegylated interferon and ribavirins who have a low viral load, noncirrhotic and nonobese may be considered for a shorter course of treatment. However, no studies have assessed host-viral factors associated with relapse in genotype 2 and 3 separately. Accordingly, we assessed whether 12 weeks of pegylated interferon and ribavirin was an optimized regimen for treatment of HCV genotype 2 and 3 with positive predictors of response. Power and sample size were a priori calculated and 96 consecutive chronic hepatitis C patients (53, genotype 2 and 43, genotype 3) without cirrhosis who were not obese and who achieved a RVR to therapy with peg-IFN-α-2a and ribavirin were enrolled. Fibrosis, steatosis, homeostatic model assessment-insulin resistance and HCV RNA were predefined variables to be evaluated in relapse. An intention-to-treat analysis was performed. SVR rates were 98% and 84% for genotype 2 and 3, respectively. Analysis of genotype 3 patients who had relapse showed a negative correlation with steatosis (P < 0.0001) and HCV RNA (P < 0.015). Multivariate analysis showed that steatosis was the independent predictor of relapse (OR, 0.988; 95% CI, 0.981-0.993; P < 0.001). Genotype 3 patients with steatosis had a relapse rate of 36.4% and 15.8% in those with high and low viral load, respectively, whereas there was no relapse in those without steatosis. In conclusion, a 12-week course of therapy is sufficient for patients without cirrhosis, not obese and infected with HCV genotype 2 achieve a RVR. This is not the case for genotype 3. Steatosis is the independent predictor of relapse. New therapeutic strategies are necessary for this subgroup of HCV genotype 3.

HOMA-AD in Assessing Insulin Resistance in Lean Noncirrhotic HCV Outpatients

Introduction. There is an association between HCV and insulin resistance (IR), which is currently assessed by HOMA-IR. There is evidence that HOMA-adiponectin (HOMA-AD) is more accurate, but its role in HCV patients is unknown. The purpose of this study was to evaluate IR in an HCV sample and controls, in order to compare the accuracy of HOMA-IR and HOMA-AD. Methods. Ninety-four HCV outpatients aged <60 years who met the criteria of nondiabetic, nonobese, noncirrhotic, and nonalcohol abusers were included and compared to 29 controls. Fasting glucose, insulin, adiponectin, and lipid profiles were determined. IR was estimated by HOMA-IR and HOMA-AD. Results. The groups were similar regarding sex and BMI, but the HCV patients were older. The median insulin level was higher in the HCV group (8.6 mU/mL (6.5-13.7) versus 6.5 (4.3-10.7), P = 0.004), as was median HOMA-IR (1.94 (1.51 to 3.48) versus 1.40 (1.02 to 2.36), P = 0.002) and the prevalence of IR (38.3% versus 10.3% (P = 0.009)). No differences were found in adiponectin levels (P = 0.294) and HOMA-AD (P = 0.393). Conclusion. IR is highly prevalent even in low-risk HCV outpatients. Adiponectin is not influenced by the presence of HCV. HOMA-AD does not seem to be useful in assessing IR in HCV patients.

Suppressor of cytokine signal 3 and IL28 genetic variation predict the viral response to peginterferon and ribavirin

AIM

  The aim of this study was to investigate the relationship among the expression of suppressor of cytokine signaling 3 (SOCS 3) in the liver, the SNPs in the IL28B locus, and the outcome of interferon therapy.

METHODS

  Prior to interferon treatment, we immunostained 67 liver specimens from chronic hepatitis C (CHC) patients who were receiving peginterferon alpha-2b/ribavirin therapy for suppressor of cytokine signaling 3 (SOCS3), and compared the expression of SOCS3, IL28 polymorphisms and other clinical factors between the patients and compared their eventual outcomes.

RESULTS

  Significant differences between the low SOCS3 group and high SOCS3 group were found in age, as well as in the platelet, transaminase, gamma-glutamyl transpeptidase levels. The incidence of high SOCS3 was not significantly different between subjects with the TT genotype and the TG genotype (TT : TG = 71%:29%, P = 0.250). In a multivariate analysis, age (≥65 years old) (odds ratio 0.221 [0.120-0.966], P = 0.045), IL28B gene (genotype TT) (odds ratio 5.422 [1.254-23.617], P = 0.024) and SOCS3 (high) (odds ratio 0.308 [0.104-0.948], P = 0.040) were significant predictors of the interferon response. In patients with the TT genotype, those with low SOCS3 immunostaining showed a high sustained virological response (69%), while the sustained virological rate was low (27%) in the patients with high SOCS3 immunostaining.

CONCLUSIONS

  Using a combination of the SOCS3 immunostained area in the liver and the expression of IL28B single nucleotide polymorphisms might be a useful predictor of hepatitis C virus clearance by interferon therapy.

Lipid and carbohydrate parameters in children with chronic hepatitis C

PURPOSE

HCV chronic infection still presents a very serious epidemiological and clinical problem. Apart from its cytopathic effect on liver parenchyma, its detrimental effect on lipid and carbohydrate metabolism has recently been emphasized. The aim of the study was to assess lipid and carbohydrate parameters in children with chronic HCV-related hepatitis.

MATERIAL/METHODS

The study comprised 41 children with chronic hepatitis C (CHC) aged between 7 and 18 years, and 30 healthy controls. The anthropometric measurements of the subjects were taken, and, after overnight fasting, serum glucose, insulin, total bilirubin, AST, ALT, total cholesterol, LDL-cholesterol, HDL-cholesterol and triglyceride levels were investigated. The HOMA IR insulin resistance index was also calculated.

RESULTS

The values for mean body mass index (BMI), glucose, insulin, bilirubin, LDL-cholesterol, HDL-cholesterol, triglycerides, HDL/C index and HOMA IR levels did not differ significantly between the two groups. AST and ALT were significantly higher in the control group. The serum levels of cholesterol and LDL-cholesterol showed a tendency toward lower values in the control group. We found positive correlation between serum levels of insulin and HOMA IR with staging (respectively r=0.336, P < 0.04 and r=0.386, P < 0.02).

CONCLUSIONS

In children with CHC and a relatively short duration of the disease, lipid and glucose disorders are not observed. Correlations between insulin and HOMA IR with staging suggest the ability of HCV to contribute to fibrosis through interference with glucose metabolism.

Total and high molecular weight adiponectin and hepatocellular carcinoma with HCV infection

Background

Adiponectin is shown to be inversely associated with development and progression of various cancers. We evaluated whether adiponectin level was associated with the prevalence and histological grade of hepatocellular carcinoma (HCC), and liver fibrosis in patients with hepatitis C virus (HCV) infection.

Methods

A case-control study was conducted on 97 HCC patients (cases) and 97 patients (controls) matched for sex, Child-Pugh grade and platelet count in patients with HCV infection. The serum total and high molecular weight (HMW) adiponectin levels were measured by enzyme-linked immunosorbent assays and examined in their association with the prevalence of HCC. In addition, the relationship between these adiponectin levels and body mass index (BMI), progression of liver fibrosis, and histological grade of HCC was also evaluated. Liver fibrosis was assessed using the aspartate aminotransferase to platelet ratio index (APRI).

Results

There were no significant differences in the serum total and HMW adiponectin levels between cases and controls. Moreover, there were no inverse associations between serum total and HMW adiponectin levels and BMI in both cases and controls. On the other hand, serum total and HMW adiponectin levels are positively correlated with APRI in both cases (r = 0.491, P<0.001 and r = 0.485, P<0.001, respectively) and controls (r = 0.482, P<0.001 and r = 0.476, P<0.001, respectively). Interestingly, lower serum total (OR 11.76, 95% CI: 2.97–46.66 [P<0.001]) and HMW (OR 10.24, CI: 2.80–37.40 [P<0.001] adiponectin levels were independent risk factors of worse histological grade of HCC.

Conclusions

Our results suggested that serum total and HMW adiponectin levels were predictors of liver fibrosis, but not prevalence of HCC in patients with HCV infection. Moreover, low these adiponectin levels were significantly associated with worse histological grades.

Steatosis is an independent predictor of relapse following rapid virologic response in patients with HCV genotype 3

BACKGROUND & AIMS

It is recommended that patients with chronic hepatitis C virus (HCV) genotype 3 infections receive 24 weeks of treatment. A rapid virologic response (RVR; at week 4) predicts a sustained virologic response (SVR), although not all patients with an RVR achieve an SVR. We explored the relationships among hepatic steatosis, level of HCV RNA, relapse, and RVR in a phase 3 randomized controlled trial of 932 patients infected with HCV genotype 2 (n = 427) or 3 (n = 505) who received 24 weeks of therapy with interferon-α.

METHODS

In patients with an RVR (HCV RNA <43 IU/mL), the presence of an SVR was modeled using multivariate logistic regression as a function of age, sex, weight, body mass index, insulin resistance, steatosis, and levels of γ-glutamyl transpeptidase, alanine aminotransferase, liver fibrosis, and baseline HCV RNA.

RESULTS

RVR, SVR, and relapse rates among patients with HCV genotype 3 were 79.6%, 79.2%, and 15.6%, respectively; corresponding rates among patients with HCV genotype 2 were 86.7%, 84.3%, and 10.1%. An RVR had high predictive value for an SVR in patients with HCV genotypes 2 (88.9%) and 3 (88.1%). The strongest independent predictors of relapse in patients with genotype 3 and an RVR were steatosis (odds ratio 3.0; P = .003) and HCV RNA ≥400,000 IU/mL (odds ratio 2.5; P = .04). Relapse rates in patients with steatosis were 17.4% and 20.9% for low and high baseline levels of HCV RNA, respectively; corresponding rates in those without steatosis were 2.5% and 8.8%.

CONCLUSIONS

Steatosis was associated with significantly higher rates of relapse, irrespective of viral load, in patients infected with HCV genotype 3 who had an RVR. Further studies are needed to determine if longer treatment durations are effective in patients with an RVR and these risk factors.

Potential role of leptin, adiponectin and three novel adipokines--visfatin, chemerin and vaspin--in chronic hepatitis

Chronic hepatitis C (CHC) is generally a slowly progressive disease, but some factors associated with rapid progression have been identified. Steatosis, independently of its metabolic or viral origin, leads to liver injury and fibrosis. It is suggested that hepatitis C virus may contribute to a wide spectrum of metabolic disturbances-namely, steatosis, insulin resistance, increased prevalence of impaired glucose tolerance, type 2 diabetes mellitus and lipid metabolism abnormalities. Adipokines, which are produced mainly by adipose tissue, may influence the inflammatory response and insulin sensitivity and contribute to the development of metabolic abnormalities in CHC and also regulate fibrogenesis and angiogenesis. Visfatin was described as an adipokine with immunomodulating and proinflammatory properties that promotes B-cell maturation and enhances activation of leukocytes, synthesis of adhesion molecules and production of proinflammatory cytokines. Visfatin exerts insulin-mimetic effects, decreases plasma glucose levels and regulates cell energy balance. Chemerin stimulates chemotaxis of dendritic cells, macrophages and natural killer (NK) cells toward the site of inflammation. On the other hand, it inhibits synthesis of proinflammatory mediators and enhances adiponectin production, influences adipocyte differentiation and maturation and regulates glucose uptake in adipocytes. Vaspin expression in human adipose tissue seems to be a compensatory mechanism associated with obesity and insulin resistance. Vaspin suppresses leptin, tumor necrosis factor (TNF)-α and resistin expression. Leptin protects against liver steatosis but accelerates fibrosis progression and exacerbates the inflammatory process. In contrast, adiponectin exerts a hepatoprotective effect. In this report, data indicating a possible role of these adipokines in the pathogenesis of chronic hepatitis are summarized.

Accumulation of refractory factors for pegylated interferon plus ribavirin therapy in older female patients with chronic hepatitis C

AIM

  Several host and viral factors have been reported to influence the effectiveness of pegylated interferon plus ribavirin combination therapy for chronic hepatitis C. In Japan, where the age of treated patients is comparatively high, recent studies have reported poor response to treatment in older female patients, but little is known about the relationship between advanced age in women and previously reported factors.

METHODS

  Using a database of 1167 patients chronically infected with hepatitis C virus (HCV) genotype 1b, we analyzed the amino acid sequences of the HCV core protein and interferon sensitivity determining region (ISDR) and examined the relationships among predictive factors.

RESULTS

  The proportion of patients with substitutions at core 70, which is associated with poor response to pegylated interferon plus ribavirin therapy, increased with age only in female patients. A similar trend was observed for ISDR wild type (wt). We also found that core 70 wt is associated with core 91 wt (P = 5.4 × 10(-9) ) as well as ISDR wt (P = 0.025). HCV RNA levels were higher in patients with core and ISDR wt (P < 0.001). Furthermore, core amino acid mutations were associated with advanced fibrosis and higher inflammatory activity (P = 0.028 and 0.048, respectively) as well as higher gamma-glutamyltranspeptidase, alanine aminotransferase and low-density lipoprotein cholesterol levels (P < 0.001, 0.006 and 0.001, respectively).

CONCLUSION

  A combination of factors account for poor response rate in older female patients in Japan. Elucidating the relationship between amino acid substitutions and metabolic alteration is an important step in understanding the mechanism of HCV interferon resistance.

Lipid accumulation impairs adiponectin-mediated induction of activin A by increasing TGFbeta in primary human hepatocytes

Fatty liver is commonly detected in obesity and has been identified as a risk factor for the progression of hepatic fibrosis in a wide range of liver diseases. Transforming growth factor beta (TGFβ) and activin A, both members of the TGFβ superfamiliy, are central regulators in liver fibrosis and regeneration, and the effect of hepatocyte lipid accumulation on the release of these proteins was studied. Primary human hepatocytes (PHH) were incubated with palmitic acid or oleic acid to increase lipid storage. Whereas activin A and its natural inhibitor follistatin were not affected, TGFβ was 2-fold increased. The hepatoprotective adipokine adiponectin dose-dependently induced activin A while lowering follistatin but did not alter TGFβ. Activin A was markedly reduced in hepatocyte cell lines compared to PHH and was not induced upon adiponectin incubation demonstrating significant differences of primary and transformed cells. In free fatty acid (FFA)-incubated PHH adiponectin-mediated induction of activin A was impaired. Inhibition of TGFβ receptors ALK4/5 and blockage of SMAD3 phosphorylation rescued activin A synthesis in FFA and in TGFβ incubated cells suggesting that FFA inhibit adiponectin activity by inducing TGFβ. To evaluate whether serum levels of activin A and its antagonist are altered in patients with hepatic steatosis, both proteins were measured in the serum of patients with sonographically diagnosed fatty liver and age- and BMI-matched controls. Systemic adiponectin was significantly reduced in patients with fatty liver but activin A and follistatin were not altered. In summary the current data demonstrate that lipid accumulation in hepatocytes induces TGFβ which impairs adiponectin bioactivity, and thereby may contribute to liver injury.

Advances in understanding the roles of leptin and adiponectin in the pathogenesis of chronic liver diseases

Leptin and adiponectin are adipokines that are abundantly expressed in adipose tissue and have multiple biological effects related to the development of human diseases. More and more studies have demonstrated that adipokines play important roles in the pathogenesis of steatosis, steatohepatitis and liver fibrosis, especially nonalcoholic fatty liver disease (NAFLD) and chronic hepatitis C (CHC). This paper reviews the recent advances in understanding the roles of leptin and adiponectin in the pathogenesis of liver diseases.

Adiponectin changes in HCV-Genotype 4: relation to liver histology and response to treatment

Recently, attention has been focussed on adiponectin and its changes in different types of chronic liver disease. Its relation to hepatic fibrosis and insulin resistance in post-hepatitis liver disease is not clear. The aim of this study was to clarify the adiponectin changes in genotype 4 hepatitis C virus (HCV)-infected patient in relation to liver histology and insulin resistance, and its usefulness as a predictor of hepatic fibrosis and response to treatment. Total adiponectin and its high molecular weight (HMW) form as well as insulin levels were studied in 92 chronic HCV, genotype 4 and 66 healthy control volunteers. Neither total adiponectin (r = 0.101, P = 0.220) nor HMW adiponectin (r = 0.081, P = 0.328) correlated with viral load. Total and not HMW adiponectin was significantly correlated with hepatic fibrosis and inflammation (r = 0.267, P = 0.002, r = 0.278, P < 0.001, respectively).In addition, total adiponectin (r = 0.224, P = 0.002) and HMW adiponectin (r = 0.266, P < 0.0006) significantly correlated with insulin resistance. As fibrosis did not correlate with insulin resistance (r = 0.081, P = 0.204), the correlation between total adiponectin and fibrosis was not mediated by insulin resistance. Multivariable regression analysis, (including pretreatment cases and controls) revealed that total adiponectin was significantly associated with gender, being lower among male subjects (X(2) = 13.04, P = 0.0001). The multivariable regression model supported the lack of association between insulin resistance and total adiponectin levels (X(2) = 1.88, P = 0.171), while non cirrhotics had significantly lower total adiponectin levels than cirrhotics (X(2) = 10.90, P = 0.004) and lower level of inflammation significantly lower total adiponectin levels than more severe inflammation (X(2) = 8.95, P = 0.003). Total or HMW adiponectin did not yield receiver operating characteristic (ROC) curves with area under the curve (AUC) >75%, thus the cutoff points have poor sensitivity/specificity as predictors of fibrosis. However, as a predictor of end-of-treatment response, the ROC curve of adiponectin index gave yield an AUC = 81.4%. We can conclude that total adiponectin level, in HCV genotype 4 patients, increases with progression of hepatic fibrosis regardless of insulin resistance. Its high molecular form does not have such correlation. The adiponectin changes are not related to viral load, insulin resistance or other demographic data suggesting that this change is histologically related. In spite of this, no adiponectin cutoff level had reasonable sensitivity/specificity for predicting hepatic fibrosis stage, while this may be used as a predictor for antiviral response possibly reflecting improvement in hepatic inflammation post treatment.

Serum levels of adipokines in patients with chronic HCV infection: relationship with steatosis and fibrosis

BACKGROUND AND AIMS

Hepatic steatosis and fibrosis are common histological findings in patients with chronic hepatitis C virus (HCV) infection. In this study we sought to determine whether serum levels of three adipokines (leptin, adiponectin and resistin) show any biochemical correlation with hepatic steatosis and fibrosis in patients with chronic HCV infection.

METHODS

We examined a total of 51 patients with chronic HCV infection (22 males and 29 females, mean BMI: 27.4+/-5kg/m(2)) and 24 healthy control subjects (10 males and 14 females, mean BMI: 23.2+/-3kg/m(2)). Liver steatosis and fibrosis were scored on biopsies. Serum levels of leptin, adiponectin and resistin were determined by ELISA.

RESULTS

HCV genotypes were 1b in 41 patients (80.4%), 3a in three patients (5.9%), 2a in two patients (3.9%), 1a in two patients (3.9%), 1c in one patient (2%), and 2b in one patient (2%). Serum levels of leptin, resistin, and the leptin-to-adiponectin ratio were significantly higher in patients with chronic HCV infection than in controls. Steatosis and fibrosis were detected in 33.3% and 70.5% of chronic HCV patients, respectively. No significant association with serum adipokine levels and degree of steatosis was evident. Low serum levels of resistin were associated with the presence of fibrosis independently of potential confounders.

CONCLUSIONS

Patients with chronic HCV infection display elevated levels of adipokines in their sera. Reduced concentrations of resistin may be a biochemical marker of fibrosis in this patient group.

Clinical trial: low plasma cholesterol and oxidative stress predict rapid virological response to standard therapy with peginterferon and ribavirin in HCV patients

BACKGROUND

Rapid virological response (RVR) is the best predictor of sustained response to standard HCV treatment.

AIM

To evaluate predictive factors of RVR.

METHODS

Sixty-five patients (mean age 52.6 +/- 13.8; 37 genotype-1, and 28 genotypes-2/3) were consecutively treated with pegIFN-alpha 2a or 2b once weekly plus daily ribavirin based on body weight for 24 or 48 weeks, according to genotype. RVR was defined as undetectable HCV-RNA at week 4.

RESULTS

Twenty-seven percent of patients achieved RVR in genotypes 1 and 60.7% in genotypes 2/3 (P < 0.01). Rapid responders had higher mean serum baseline total and LDL-cholesterol levels (P < 0.01). RVR was 20.0% in the bottom tertile of total cholesterol and 63.6% in the top tertile (P < 0.01). HCV-RNA levels at week 4 were positively correlated with baseline serum insulin (P < 0.01), HOMA-IR (P < 0.01), body mass index (P < 0.05) and number of components of metabolic syndrome (P < 0.01) and negatively correlated with cholesterol levels (P < 0.05). At multivariate analysis, age, LDL-cholesterol, HCV genotype and serum 8-iso-PGF 2 alpha, a marker of oxidative stress, were independent predictors of RVR.

CONCLUSIONS

Our prospective study supports a role of low serum total and LDL-cholesterol and of oxidative stress as positive independent predictive factors of poor RVR in HCV patients.

Adipokines in liver diseases

Adipokines are polypeptides secreted in the adipose tissue in a regulated manner. While some of these molecules are expressed only by adipocytes, resident and infiltrating macrophages and components of the vascular stroma markedly contribute to expression of other adipokines. As a result, adipose tissue inflammation is associated with a modification in the pattern of adipokine secretion. Leptin, adiponectin, and resistin are the best-studied molecules in this class, but cytokines such as tumor necrosis factor or interleukin-6 are also secreted at high levels by the adipose tissue. Several other molecules have been recently identified and are actively investigated. Adipokines interfere with hepatic injury associated with fatty infiltration, differentially modulating steatosis, inflammation, and fibrosis. Several studies have investigated plasma levels of adiponectin in patients with nonalcoholic fatty liver disease, to establish correlations with the underlying state of insulin resistance and with the type and severity of hepatic damage. Hepatitis C is another disease where adipokines may represent a link between viral infection, steatosis, and metabolic disturbances. Identification of the mediators secreted by expanded adipose tissue and their pathogenic role is pivotal in consideration of the alarming increase in the prevalence of obesity and of the detrimental role that this condition exerts on the course of liver diseases.

Adiponectin-stimulated CXCL8 release in primary human hepatocytes is regulated by ERK1/ERK2, p38 MAPK, NF-kappaB, and STAT3 signaling pathways

Adiponectin is believed to exert hepatoprotective effects and induces CXCL8, a chemokine that functions as a survival factor, in vascular cells. In the current study, it is demonstrated that adiponectin also induces CXCL8 expression in primary human hepatocytes but not in hepatocellular carcinoma cell lines. Knock down of the adiponectin receptor (AdipoR) 1 or AdipoR2 by small-interfering RNA indicates that AdipoR1 is involved in adiponectin-stimulated CXCL8 release. Adiponectin activates nuclear factor (NF)-kappaB in primary hepatocytes and pharmacological inhibition of NF-kappaB, the p38 mitogen-activated protein kinase, and extracellular signal-regulated kinase (ERK) 1/ERK2 reduces adiponectin-mediated CXCL8 secretion. Furthermore, adiponectin also activates STAT3 involved in interleukin (IL)-6 and leptin-mediated CXCL8 induction in primary hepatocytes. Inhibition of JAK2 by AG-490 does not abolish adiponectin-stimulated CXCL8, indicating that this kinase is not involved. Pretreatment of primary cells with "STAT3 Inhibitor VI," however, elevates hepatocytic CXCL8 secretion, demonstrating that STAT3 is a negative regulator of CXCL8 in these cells. In accordance with this assumption, IL-6, a well-characterized activator of STAT3, reduces hepatocytic CXCL8. Therefore, adiponectin-stimulated induction of CXCL8 seems to be tightly controlled in primary human hepatocytes, whereas neither NF-kappaB, STAT3, nor CXCL8 are influenced in hepatocytic cell lines. CXCL8 is a survival factor, and its upregulation by adiponectin may contribute to the hepatoprotective effects of this adipokine.

Hepatitis C and diabetes: the inevitable coincidence?

Type 2 diabetes (T2D) and HCV infection are common conditions involving, respectively, at least 170 and 130 million people worldwide. However, the distribution of such cases does not overlap in the same age groups in different geographic areas. Following pioneering reports of increased prevalence of T2D in HCV-positive cirrhosis, interest concerning the relationship between HCV and T2D has escalated. HCV is able to induce insulin resistance (IR) directly and the role of specific viral genotypes responsible for such effect is disputed. IR has consistently been found to be closely linked to fibrosis in HCV infection, although also typically associated with T2D in prefibrotic stages. HCV infection could be associated with a reduced prevalence of metabolic syndrome owing to virus-associated reduction in BMI (reported in population but not clinical studies) and hypobetaliproteinemia. A three- to ten-fold increased risk of HCV infection was reported among diabetic patients in comparison with different control groups and a meta-analysis showed a 1.8-fold excess risk of T2D among HCV-positive compared with HBV-positive patients. Moreover, HCV positivity is associated with an increased risk of T2D in patients receiving liver or kidney transplantations. T2D and IR are independent predictors of a more rapid progression of liver fibrosis and impaired response to antiviral treatment in chronic hepatitis C. Patients with cirrhosis and T2D have an increased susceptibility to hepatic encephalopathy and hepatocellular carcinoma (HCC). However, the beneficial effects of antiviral treatment on IR and T2D are controversial. Theoretically, glycemic control in chronic hepatitis C, and particularly in cirrhotic patients, could improve the prognosis and the response to antivirals, although the evidence for this is limited. Future studies should elucidate the relationship between insulin signaling, HCV and interferon signaling, entity of cardiovascular risk in patients with HCV infection, the potential role of 'metabolic' strategies added to antiviral treatment schedules, the impact of IR on liver failure, portal hypertension and HCC, particularly in patients managed in a transplant setting.

Adipocytokines and liver disease

Adipose tissue is a massive source of bioactive substances known as adipocytokines, including tumor necrosis factor (TNF)-alpha, resistin, leptin, and adiponectin. Recent advances in medical research view obesity as a chronic low-grade inflammatory state. Hypertrophied adipocytes in obesity release chemokines that induce macrophage accumulation in adipose tissue. Accumulated macrophages in obese adipose tissue produce proinflammatory cytokines and nitric oxide, and these inflammatory changes induce adipocytokine dysregulation. The latter is characterized by a decrease in insulinsensitizing and anti-inflammatory adipocytokines, and an increase in proinflammatory adipocytokines. Adipocytokine dysregulation induces obesity-related metabolic disorders, the so-called metabolic syndrome. Metabolic syndrome is a cluster of metabolic abnormalities, including diabetes mellitus, hypertension, hyperlipidemia, and nonalcoholic steatohepatitis (NASH). Recent studies have revealed that obesity is an independent risk factor for chronic liver diseases, such as NASH, alcoholic liver disease, chronic hepatitis C, and hepatocellular carcinoma. A common mechanism underlying these hepatic clinical states is thought to be adipocytokine dysregulation. In this review, we discuss the association of adipocytokines, especially leptin, adiponectin, TNF-alpha, and resistin, with liver diseases.

Hepatic steatosis in patients with chronic hepatitis C virus genotype 2 or 3 does not affect viral response in patients treated with peginterferon alpha-2a (40KD) (PEGASYS) plus ribavirin (COPEGUS) for 16 or 24 weeks

BACKGROUND

Hepatic steatosis is common in patients infected with hepatitis C virus (HCV). The effect of steatosis on anti-HCV therapy efficacy is unclear.

METHODS

We studied host and viral factors associated with steatosis and the effect of steatosis on treatment efficacy using the database of a large prospective trial in patients with HCV genotypes 2 and 3.

RESULTS

Out of 885 patients assessed for steatosis, a total of 614 patients or 69% had steatosis. Patients with genotype 3 were more likely to have steatosis than those with genotype 2 (79 vs. 59%, P<0.001). Using the logistic regression model, steatosis was associated with genotype 3 (P<0.0001), older age (P=0.0025), heavier weight (P<0.0001), higher HCV RNA (P<0.0001), and higher ALT levels (P=0.015). By univariate analysis, steatosis was associated with lower sustained virological response (SVR) in patients with genotype 3, but not in patients with genotype 2. When all factors associated with steatosis and SVR were evaluated by logistic regression analysis; genotype, age, bodyweight, histological diagnosis, ALT quotient, baseline HCV RNA and treatment duration were associated with the probability of SVR, but gender, race and steatosis were not. Further analysis showed that steatosis remained a non-significant factor while baseline viral load was significantly associated with the probability of an SVR.

CONCLUSIONS

Steatosis did not influence the efficacy of treatment in our study population. Baseline viral load is a confounding factor, particularly in patients infected with genotype 3 and once baseline viral load was accounted for, the association between steatosis and SVR was not relevant.

Research progress of leptin and adiponectin in chronic liver diseases

Leptin and adiponectin, the main metabolic products of adipose tissues, have been implicated in a wide spectrum of human diseases. There is currently increasing interest in the role of these adipokines in the development of chronic liver diseases, mostly in patients with nonalcoholic fatty liver disease, chronic hepatitis C or cirrhosis. According to experimental data, increased leptin and decreased adiponectin serum levels have been detected initially in patients with nonalcoholic steatohepatitis and more recently in chronic HCV-infected patients compared to healthy controls in most but not all studies, while the data on the associations between these adipokine levels and the development of chronic liver disease are still rather conflicting. Therefore, we summarize the progress of leptin and adiponectin in chronic liver diseases.