Insulin resistance is a major determinant of sustained virological response in genotype 1 chronic hepatitis C patients receiving peginterferon alpha-2b plus ribavirin

Green Tea (Camellia sinensis): A Review of Its Phytochemistry, Pharmacology, and Toxicology

Objectives Green tea (Camellia sinensis) is a kind of unfermented tea that retains the natural substance in fresh leaves to a great extent. It is regarded as the second most popular drink in the world besides water. In this paper, the phytochemistry, pharmacology, and toxicology of green tea are reviewed systematically and comprehensively. Key findings Green tea has been demonstrated to be good for human health. Nowadays, multiple pharmacologically active components have been isolated and identified from green tea, including tea polyphenols, alkaloids, amino acids, polysaccharides, and volatile components. Recent studies have demonstrated that green tea shows versatile pharmacological activities, such as antioxidant, anticancer, hypoglycemic, antibacterial, antiviral, and neuroprotective. Studies on the toxic effects of green tea extract and its main ingredients have also raised concerns including hepatotoxicity and DNA damage. Summary Green tea can be used to assist the treatment of diabetes, Alzheimer’s disease, oral cancer, and dermatitis. Consequently, green tea has shown promising practical prospects in health care and disease prevention.

Racial Disparities in Hepatitis C Treatment Eligibility

BACKGROUND

Hepatitis C (HCV) is more prevalent in African Americans than in any other racial group in the United States. However, African Americans are more likely to be deemed ineligible for HCV treatment than non-African Americans. There has been limited research into the origins of racial disparities in HCV treatment eligibility.

AIM

The purpose of this study was to compare medical and non-medical characteristics commonly assessed in clinical practice that could potentially contribute to HCV treatment ineligibility disparities between African American and non-African American patients.

MATERIAL AND METHODS

Patients with confirmed HCV RNA considering treatment (n = 309) were recruited from university-affiliated and VA liver and infectious disease clinics.

RESULTS

African Americans and non-African Americans did not differ in prevalence of lifetime and current psychiatric disorders and risky behaviors, and HCV knowledge. HCV clinical characteristics were similar between both groups in terms of HCV exposure history, number of months aware of HCV diagnosis, stage of fibrosis, and HCV virologic levels. African Americans did have higher proportions of diabetes, renal disease, and bleeding ulcer.

CONCLUSIONS

No clinical evidence was found to indicate that African Americans should be more often deemed ineligible for HCV treatment than other racial groups. Diabetes and renal disease do not fully explain the HCV treatment ineligibility racial disparity, because HCV patients with these conditions are priority patients for HCV treatment because of their greater risk for cirrhosis, steatosis, and hepatocellular carcinoma. The findings suggest that an underlying contributor to the HCV treatment eligibility disparity disfavoring African Americans could be racial discrimination.

Metformin activates type I interferon signaling against HCV via activation of adenosine monophosphate-activated protein kinase

Activation of the type I interferon (IFN) signaling pathway is essential for the eradication of hepatitis C virus (HCV). Metformin can activate adenosine monophosphate-activated protein kinase (AMPK) to reduce insulin resistance. Cross talks between AMPK and IFN signaling remain unclear. To understand the influence of metformin on the type I IFN signaling pathway and HCV infection, the full-length HCV replicon OR6 cells and the infectious HCV clones JFH1 were used to assess the anti-HCV effect of the insulin sensitizers, metformin and pioglitazone. Immunofluorescence staining and the immunoblotting of HCV viral protein demonstrated that metformin, but not pioglitazone, inhibited HCV replication in OR-6 and JFH-1-infected Huh 7.5.1 cells. Immunoblotting data showed that metformin activated the phosphorylation of STAT-1 and STAT-2 in OR-6 and JFH-1 infected Huh 7.5.1 cells. Metformin enhanced the phosphorylation of AMPK, and the metformin-activated IFN signaling was down-regulated by AMPK inhibitor. After treatment of AMPK inhibitor, the level of HCV core protein decreased by metformin can be rescued. In conclusion, metformin activates type I interferon signaling and inhibits the replication of HCV via activation of AMPK.

Treatment of type 2 diabetes mellitus by viral eradication in chronic hepatitis C: Myth or reality?

Chronic hepatitis C is a systemic disease inducing metabolic alterations leading to extrahepatic consequences. In particular, hepatitis C virus (HCV) infection seems to increase the risk of incident type 2 diabetes mellitus in predisposed individuals, independently of liver disease stage. The mechanisms through which hepatitis C induces T2DM involve direct viral effects, insulin resistance, pro-inflammatory cytokines and other immune-mediated processes. Many studies have reported the clinical consequences of type 2 diabetes mellitus on hepatitis C outcome, but very few studies have addressed the issue of microangiopathic complications among patients with hepatitis C only, who develop type 2 diabetes mellitus. Moreover, clinical trials in HCV-positive patients have reported improvement in glucose metabolism after antiviral treatment; recent studies have suggested that this metabolic amelioration might have a clinical impact on type 2 diabetes mellitus-related complications. These observations raise the question as to whether the HCV eradication may also have an impact on the future morbidity and mortality due to type 2 diabetes mellitus. The scope of this review is to summarise the current evidence linking successful antiviral treatment and the prevention of type 2 diabetes mellitus and its complications in hepatitis C-infected patients.

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.

Low-density lipoprotein and other predictors of response with telaprevir-based therapy in treatment-experienced HCV genotype 1 patients: REALIZE study

BACKGROUND & AIMS

Predictors of response to treatment with peginterferon plus ribavirin are well established. In these post-hoc analyses of the REALIZE study, we sought to identify predictors of response for telaprevir-based triple therapy.

METHODS

Patients from the REALIZE study with baseline data for all predictors evaluated (including baseline disease characteristics and demographics, prior treatment response and baseline laboratory assessments) were included in the post-hoc analyses (n = 465). Univariate and multivariate analyses were used to evaluate factors predicting treatment outcomes.

RESULTS

Sustained viral response (SVR) rates were 86% in prior relapsers, 63% in prior partial responders and 32% in prior null-responders. In the final multivariate analysis, baseline factors predicting SVR were prior response to treatment [Odds ratio (OR) = 2.80; 95% confidence interval (CI), 2.13-3.69], low-density lipoprotein (LDL) (≥2.6 mmol/L) (OR = 2.11; 95% CI, 1.52-2.93), HCV genotype (OR = 0.58; 95% CI, 0.36-0.93), and maximum alanine amino transferase and aspartate amino transferase (OR = 0.62; 95% CI, 0.40-0.97).

CONCLUSIONS

Prior response to peginterferon plus ribavirin treatment and LDL levels are the main independent predictive markers of response with telaprevir-based triple therapy.

Reversal, maintenance or progression: what happens to the liver after a virologic cure of hepatitis C?

A sustained virological response (SVR) from HCV (synonymous with virological cure) leads to decreased mortality, morbidity and improved quality of life, as well as a reduced incidence of liver disease progression, including liver failure, cirrhosis and hepatocellular carcinoma. Large clinical trials comparing pre- and post-treatment liver biopsies demonstrate improvements in inflammation as well as fibrosis score following SVR. However, a small subset of patients display persistent hepatic inflammation and/or progress to cirrhosis despite SVR. In addition to conferring a risk of fibrosis progression, advanced fibrosis pre-treatment is a major risk factor for post-SVR hepatocellular carcinoma. In this review, we discuss the mechanisms of fibrosis regression uncovered using experimental fibrosis models and highlight potential mechanisms in those few patients with fibrosis progression despite SVR. We also introduce current concepts of fibrosis-dependent tumorigenesis post-SVR in patients with advanced disease. This article forms part of a symposium in Antiviral Research on "Hepatitis C: next steps toward global eradication."

[Efficacy of peginterferon and ribavirin combination therapy of chronic hepatitis C: a pooled analysis]

BACKGROUND/AIMS

A combination of peginterferon and ribavirin is the standard therapy for chronic hepatitis C (CHC). However, the respective study has not been carried out in a large scale in Korea. The purpose of this study was to collect the studies that have been reported in Korea in order to analyze the therapeutic effect of combination therapy and compare to find racial difference.

METHODS

Twenty-eight papers related to the therapeutic effect of combination therapy in CHC patients were analyzed based on pooled analysis.

RESULTS

Based on the analysis for genotype 1 in Korea, early virologic response (EVR), end of treatment response (ETR), and sustained virologic response (SVR) were 79.6% (125/157), 80.1% (166/207), and 62.7% (341/543). The EVR, ETR, and SVR for genotype 2 and 3 were 89.4% (119/133), 92.2% (203/220), and 84.1% (434/516). Data from other Asians showed that EVR and SVR for genotype 1 were 88.9% (290/326) and 64.4% (491/762) respectively and 88.8% (135/152), and 79.4% (151/190) for genotype 2 and 3 respectively. In Western, EVR and SVR for genotype 1 were 51.3% (1,981/3,860) and 42.4% (1,798/4,231) respectively, and for genotype 2 and 3 were 87.7% (350/399) and 77.8% (533/685) respectively. Based on the comparative analysis, no statistical difference in SVR between Koreans and other Asians (p=0.955) was observed; However, the SVR of Koreans was higher with significance than that of Westerns (p<0.001) On the other hand, there was no difference what so ever, in SVR for genotype 2 amongst the different races.

CONCLUSIONS

The SVR of combination therapy for the Korean chronic hepatitis C patients was similar to other Asians but higher than Westerns.

Baseline high viral load and unfavorable patterns of alanine aminotransferase change predict virological relapse in patients with chronic hepatitis C genotype 1 or 2 obtaining rapid virological response during antiviral therapy

BACKGROUND

Rapid virological response (RVR) strongly predicts sustained virological response (SVR) in patients with chronic hepatitis C (CHC), and abbreviates antiviral therapy in some patients.

OBJECTIVES

To identify factors predicting virological relapse (VR) in CHC patients who attained RVR.

PATIENTS AND METHODS

Medical records of 133 CHC patients with an RVR after completing 24 weeks of antiviral therapy (a combination of pegylated interferon-α and ribavirin) were analyzed. Baseline characteristics and on-treatment responses were compared between the patients with an SVR and those with VR. Patients with normal alanine aminotransferase (ALT) levels at weeks 4 and 12 and at the end-of-treatment (EoT) and patients with elevated, but constantly decreasing, ALT levels were classified as having favorable patterns of ALT change. A trend of increasing ALT levels either between weeks 4 and 12 or between weeks 12 and EoT was classified as unfavorable. A high viral load (HVL) was defined as a baseline HCV RNA ≥ 600000 IU/mL.

RESULTS

In total, 116 (87.2%) patients had a SVR and 14 (10.5%) had VR. The VR rates were comparable between patients with genotype-1 (13.1%) and genotype-2 infection (8.7%) (P = 0.572). Multivariate analysis revealed that HVL (P = 0.015; odds ratio [OR] = 14.754; 95% confidence interval (CI) = 1.671-130.240), and unfavorable ALT patterns (P = 0.039; OR = 4.397; 95% CI = 1.078-17.930) independently predicted VR. In subgroup analysis, low viral load (LVL) patients had a minimal VR rate (1.8%). Among the HVL patients, the VR rate of those using peg-IFN-α-2a was relatively low (9.1%). Patients using peg-IFN-α-2b had a slightly higher VR rate (23.8%; P = 0.128), and patients with favorable patterns of ALT changes had a lower VR rate (10.3%) compared to the 53.8% in patients with unfavorable ALT patterns (P = 0.005).

CONCLUSIONS

In southern Taiwan, 24 weeks of antiviral therapy achieved a high SVR rate in patients with CHC attaining RVR, except in the subgroup of patients treated with peg-IFN-α-2b with HVL and on-treatment unfavorable ALT patterns.

Association between insulin resistance and sustained virologic response in hepatitis C treatment, genotypes 1 versus 2 and 3: systematic literature review and meta-analysis

Background/aims

Controversial results have been found in literature for the association between insulin resistance and sustained virologic response to standard chronic hepatitis C treatment. This study aims to provide a systematic literature review with meta-analysis, in order to evaluate if insulin resistance interferes with sustained virologic response in patients infected by the HCV genotype 1 versus HCV genotypes 2 and 3, undergoing treatment with interferon and ribavirin or pegylated interferon and ribavarin.

Methods

Systematic search was performed on main electronic databases until May 2012. Primary outcome was sustained virologic response, defined as undetectable levels of HCV-RNA six months after the end of treatment. Meta-analytic measure was estimated using Dersimonian and Laird's method, using Stata software.

Results

Thirteen studies involving 2238 infected patients were included. There was a statistically significant association between insulin resistance and lower sustained virologic response rate, and this difference occurred in HCV genotype G1 (OR: 2.23; 95% CI: 1.59–3.13) and G2/G3 (OR: 4.45; 95% CI: 1.59–12.49). In addition, a difference was seen in the cut-offs used for defining insulin resistance by Homeostasis Model Assessment of Insulin Resistance. To minimize this limitation, sub-analysis that excluded the studies that did not use 2 as a cut-off value was performed and the results still demonstrated association between insulin resistance and sustained virologic response, for both genotypic groups.

Conclusion

This meta-analysis provides evidence that elevated Homeostasis Model Assessment of Insulin Resistance is associated with a lower sustained virologic response rate in patients with hepatitis C treated with interferon and ribavirin or pegylated interferon and ribavarin, regardless of their genotype.

Insulin resistance, steatosis and hepatitis C virus

Epidemiological studies have shown an increased occurrence of metabolic disorders such as insulin resistance (IR) and steatosis in patients with hepatitis C virus (HCV) infection. IR is believed to represent one of the central clinical features of the "metabolic syndrome" and the major pathogenetic factor for type 2 diabetes mellitus. In patients with chronic HCV hepatitis, IR may have several dangerous consequences such as accelerated progression of liver fibrosis, resistance to antiviral therapy and development of hepatocellular carcinoma. According to recent evidence, the global epidemic of metabolic disorders related to incorrect diets will lead physicians to deal with 1.2 billion patients with diabetes in the world in 2025. Given the high prevalence of HCV infection in several countries, metabolic manifestations will contribute to increasing morbidity and mortality in patients with HCV chronic infection in the near future. HCV treatment, shown able to decrease both the occurrence of HCV-related IR and diabetes, may reduce the risk of the associated morbidities.

Altered trace mineral milieu might play an aetiological role in the pathogenesis of polycystic ovary syndrome

Insulin resistance is a very common associate of polycystic ovary syndrome (PCOS). Pathophysiology in relation with the essential elements including copper, magnesium, zinc, manganese, chromium, and calcium has been reported in women with insulin resistance. This prospective study was designed to explore whether the women with PCOS do exhibit altered serum element levels in association with/without insulin resistance. One hundred and thirty-two women with PCOS and forty-six control women were studied. Women with PCOS were further divided based on the presence of insulin resistance (insulin resistant: n = 50; non-insulin resistant: n = 82). In all women, basal levels of gonadotropins, prolactin, testosterone, insulin, glucose, and the six different elements were measured. Serum levels of testosterone (p < 0.001), luteinizing hormone (p < 0.05), and fasting insulin (p < 0.004) were significantly higher in the PCOS population compared to controls as well as PCOS women without insulin resistance. Women with PCOS exhibited a significantly high calcium (p < 0.04) and lower manganese levels (p < 0.002) when compared to controls. However, the PCOS women with insulin resistance exhibited significantly lower serum levels of magnesium and chromium (p < 0.04), in addition to higher levels of zinc and copper (p < 0.04). The differences in calcium (p < 0.03) and manganese levels (p < 0.0001) became aggravated with the presence of insulin resistance when compared to control as well as PCOS women without insulin resistance. In PCOS-associated insulin resistance, circulating serum magnesium (r = -0.31; p < 0.03) and chromium (r = -0.38; p < 0.006) status significantly correlated with fasting insulin levels. We conclude that imbalanced element status may be a key foundation for insulin resistance in PCOS. The findings in this study should be investigated with further trials in order to obtain new insights into PCOS.

[Chronic hepatitis C and insulin resistance]

Insulin resistance is frequently associated with chronic liver disease, and the interaction between hepatitis C virus (HCV) infection and insulin resistance is a major public health issue, bound to increase in the near term. Because of their potential synergism on liver disease severity, a better understanding of the clinical consequences of the relationship between HCV infection and insulin resistance is needed. This translates into accelerated liver disease progression, reduced response to anti-viral agents and, in susceptible individuals, increased risk of developing type 2 diabetes. HCV may also cause hepatic steatosis, especially in patients infected with genotype 3, although the clinical impact of viral steatosis is debated. Little is known regarding the effect of anti-diabetic agents on HCV infection, and a possible association between use of exogenous insulin or a sulfonylurea agents and the development of hepatocellular carcinoma has recently been reported. Thus, modified lifestyle and pharmacological modalities are urgently warranted in chronic hepatitis C with metabolic alterations.

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.

Insulin resistance in non-diabetic patients with chronic hepatitis C: what does it mean?

OBJECTIVES

To determine the prevalence of insulin resistance (IR) in non-diabetic patients with chronic hepatitis C, and to assess the association between IR, laboratory parameters and histological findings.

SUBJECTS AND METHODS

Eighty-two patients had their serum analyzed for glucose, lipid profile, C-reactive protein (CRP), ferritin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), HOMA-IR, viral load and HCV genotype. Patients with HOMA-IR levels > 2.5 were considered as carriers of insulin resistance.

RESULTS

IR was observed in 27% of patients and was associated with age, waist circumference and body mass index. IR patients were more likely to have more advanced hepatic fibrosis and necroinflammatory activity, higher levels of aminotransferases and liver steatosis than patients without IR.

CONCLUSIONS

Insulin resistance is often present in patients with chronic hepatitis C, and this parameter is associated with more advanced HCV-related hepatic fibrosis.

Type 2 diabetes mellitus and chronic hepatitis C: which is worse? Results of a long-term retrospective cohort study

BACKGROUND

The long-term outcome in patients with chronic hepatitis C and type 2 diabetes mellitus treated with interferon and ribavirin is unclear. We compared incidence of liver-related events and mortality rates between hepatitis C virus-positive patients with or without diabetes mellitus, and the incidence of diabetes-related events between diabetic patients with and without hepatitis C.

METHODS

Retrospective study of 309 patients with chronic hepatitis C. Incidence of liver-related events, diabetes-related events and mortality rates were assessed over a mean follow-up of 11.02±4.9 years.

RESULTS

50 (16%) chronic hepatitis C patients had diabetes mellitus. Diabetics showed a higher number of diabetes- and liver-related events than non-diabetics (10% vs 1.5%, p=0.006; 18% vs 5.7%, p=0.007, respectively) with a mortality of 14% vs 1.5% (p=0.0003). Baseline cirrhosis (p=0.002) and non-sustained virological response (p=0.01) were independent risk factors for liver events; diabetes mellitus (p=0.01) and hypertension (p=0.0017) were independent factors for diabetes-related events.

CONCLUSIONS

In patients with chronic hepatitis C, comorbidity with diabetes mellitus was associated with a higher mortality rate and incidence of liver/diabetes-related events. Independent risk factors for liver-related events were the non-response to antiviral therapy and cirrhosis at baseline.

Hepatitis C virus induced insulin resistance impairs response to anti viral therapy

Hepatitis C virus (HCV) infection is an important risk factor for insulin resistance (IR). The latter is the pathogenic foundation underlying metabolic syndrome, steatosis and cirrhosis, and possibly hepatocellular carcinoma (HCC). The interplay between genetic and environmental risk factors ultimately leads to the development of IR. Obesity is considered a major risk factor, with dysregulation of levels of secreted adipokines from distended adipose tissue playing a major role in IR. HCV-induced IR may be due to the HCV core protein inducing proteasomal degradation of insulin receptor substrates 1 and 2, blocking intracellular insulin signaling. The latter is mediated by increased levels of both tumour necrosis factor-α (TNF-α) and suppressor of cytokine signaling 3 (SOC-3). IR, through different mechanisms, plays a role in the development of steatosis and its progression to steatohepatitis, cirrhosis and even HCC. In addition, IR has a role in impairing TNF signaling cascade, which in turn blocks STAT-1 translocation and interferon stimulated genes production avoiding the antiviral effect of interferon.

Steatosis and insulin resistance in response to treatment of chronic hepatitis C

This review will focus on the impact of steatosis and insulin resistance on the response to antiviral therapy for chronic hepatitis C. Hepatitis C virus (HCV) infection is known to have direct and/or indirect effects on lipid and glucose metabolism, leading to, among other disturbances, steatosis and insulin resistance, respectively. Some of these disturbances have a marked HCV genotype distribution. For example, on average, patients with HCV genotype 3 have the highest prevalence and severity of viral fatty liver. On the other hand, the current global spread of the metabolic syndrome represents a formidable cofactor of morbidity in HCV-related chronic liver disease. Thus, the pathogenesis of steatosis and insulin resistance in patients with chronic hepatitis C may often be dual, i.e. viral and metabolic. This distinction is relevant because the effect (if any) of steatosis or insulin resistance on the response to antiviral agents seems to depend on their pathogenesis. Accumulating data suggest that viral fatty liver may not impact on response to therapy, while metabolic steatosis does. Similarly, viral insulin resistance may not reduce the rate of response to therapy to the same extent that metabolic insulin resistance does. Some implications for patient management are discussed.

The determination of GGT is the most reliable predictor of nonresponsiveness to interferon-alpha based therapy in HCV type-1 infection

BACKGROUND

The critical analysis of baseline factors has been found to be useful to predict virologic nonresponse (NR), relapse, or sustained virologic response (SVR) in patients infected with hepatitis C virus (HCV) who receive antiviral therapy. In the present retrospective study we tried to find out whether gamma-glutamyltranspeptidase (GGT) may be one of the baseline factors which are of special predictive power. We analyzed, in patients with different treatment outcomes, the predictive power of established baseline factors either in combination with GGT or by evaluating the predictive value of GGT independently.

METHODS

Individual data from 632 patients chronically infected with HCV type 1 (n = 561) or type 2/3 (n = 71) were analyzed. All patients had received their first course of antiviral therapy and were treated with pegylated interferon α-2a or -2b plus ribavirin.

RESULTS

In patients with HCV type 1, a multivariate multinomial logistic regression analysis identified low GGT (p < 0.0001), high cholesterol (p < 0.0001), age ≤ 40 years (p < 0.0001), high alanine aminotransferase (p = 0.0006), low viremia (p = 0.0014), and absence of cirrhosis (p = 0.0164) as independent predictors. While these baseline factors heralded improved virologic response, high GGT, in contrast, was significantly associated with NR (p < 0.0001). A strong correlation was found between log(10) GGT and a scoring variable S (r = -0.26 for prediction of SVR, p < 0.001; r = 0.11 for prediction of NR, p = 0.016) summarizing predictive information from other baseline factors.

CONCLUSIONS

These findings prove the predictive sensitivity of GGT as an independent indicator of nonresponsiveness even at levels that are slightly above the normal range. This new predictive parameter may help to improve individualized therapy in HCV type-1 infection.

Impact of insulin resistance on sustained response in HCV patients treated with pegylated interferon and ribavirin: a meta-analysis

BACKGROUND & AIMS

Recent studies suggested that SVR rates might be lower in HCV patients with insulin resistance (IR) than in patients without IR, but the extent of the impact of IR on treatment response has not been established. We aimed to confirm the role of IR assessed by the homoeostasis model assessment (HOMA-IR) on SVR and to determine its magnitude.

METHODS

We performed meta-analysis of studies evaluating the impact of IR in HCV patients treated with pegylated interferon and ribavirin.

RESULTS

Fourteen studies involving 2732 patients were included. SVR was less frequent in patients with IR than in patients without IR (mean difference: -19.6%, 95% CI: -29.9% to -9.4%, p<0.001). In sensitivity analyses according to HCV-1 patients, patients with IR also less frequently attained a SVR than patients without IR (mean difference: -13.0%, 95% CI: -22.6% to -3.4%, p=0.008). In addition, the baseline HOMA-IR index was lower in responders than in non-responders (mean difference: -0.92, 95% CI: -1.53 to -0.32, p<0.001). In sensitivity analyses restricted to HCV-1 patients, the baseline HOMA-IR index remained lower in responders than in non-responders (mean difference: -0.63, 95% CI: -1.13 to -0.14, p<0.001).

CONCLUSIONS

HCV patients with IR have a 20% lower SVR than patients without IR. The baseline HOMA-IR index is a major determinant of SVR.

Peroxisome proliferator-activated receptors and hepatitis C virus

The prevalence of type 2 diabetes mellitus and insulin resistance are higher among people chronically infected with hepatitis C (CHC) when compared with the general population and people with other causes of chronic liver disease. Both insulin resistance and diabetes are associated with adverse outcomes across all stages of CHC, including the liver transplant population. CHC is also associated with the development of hepatic steatosis, a common histological feature present in approximately 55% (32-81%) of cases. There is a complex interrelationship between insulin resistance and hepatic steatosis and both are postulated to aggravate each other. The peroxisome proliferator-activated receptors (PPARs) are nuclear factors involved in the regulation of glucose, lipid homeostasis, inflammatory response, cell differentiation, and cell cycle. The relationship between hepatitis C virus replication and PPARs has been the focus of recent study. Given the availability of potent agonists, PPARs may represent a novel pharmacological target in the treatment of CHC.

Use of HOMA-IR in hepatitis C

Chronic infection with hepatitis C virus (HCV) can induce insulin resistance (IR) in a genotype-dependent manner and contributes to steatosis, progression of fibrosis and resistance to interferon plus ribavirin therapy. Our understanding of HCV-induced IR has improved considerably over the years, but certain aspects concerning its evaluation still remain elusive to clinical researchers. One of the most important issues is elucidating the ideal method for assessment of IR in the setting of hepatitis C. The hyperinsulinaemic euglycaemic clamp is the gold standard method for determining insulin sensitivity, but is impractical as it is labour intensive and time-consuming. To date, all human studies except for four where IR was evaluated in the HCV setting, an estimation of IR has been used rather than direct measurements of insulin-mediated glucose uptake. The most commonly used estimation in the HCV population is the homeostasis model assessment of insulin resistance (HOMA-IR) which is calculated from a single measurement of fasting insulin and glucose. In this article, we review the use and reporting of HOMA in the literature and provide guidance on its appropriate as well as inappropriate use in the hepatitis setting.

Metabolic alterations and chronic hepatitis C: treatment strategies

INTRODUCTION

Chronic hepatitis C (HCV) infection is considered a metabolic disease. It is associated with a specific metabolic syndrome, HCV-associated dysmetabolic syndrome (HCADS), consisting of steatosis, hypocholesterolemia and insulin resistance/diabetes. These metabolic derangements contribute to a decrease in sustained virological response (SVR) to pegylated-interferon-α-ribavirin as standard of care (SOC), and are associated with progression of liver fibrosis.

AREAS COVERED

The review, highlighting the impact of HCADS and metabolic syndrome components of HCV disease progression and SOC, discusses current knowledge and perspectives on metabolic therapeutic strategies aimed at improving SVR rate of SOC for chronic hepatitis C.

EXPERT OPINION

HCV, features of HCADS and of metabolic syndrome may coexist in the same patient, thus all components of the metabolic syndrome must be assessed to individualize treatment. The results of therapeutic trials evaluating metabolic strategies combined with current SOC indicate that weight loss is a critical part of treatment which will improve both disease outcome and therapeutic response to SOC. Similarly, statins seem to improve response rate to SOC representing, once confirmed to be safe, an important therapeutic tool for HCV-infected patients. Findings from studies using insulin sensitizers combined with SOC are not conclusive and do not justify the use of this class of drugs in clinical practice.

Current understanding of insulin resistance in hepatitis C

Important breakthroughs have been made in recent years into understanding the close interaction between hepatitis C virus (HCV) infection and glucose homeostasis. Both cross-sectional and longitudinal studies have demonstrated that infection with HCV is associated with an increased risk of developing insulin resistance and Type 2 diabetes. A direct effect of HCV on hepatocyte insulin signaling has been shown in experimental models. Some preliminary observations seem to suggest that indirect mechanisms involving extrahepatic organs might also play a role. The interaction between HCV and glucose metabolism has significant clinical consequences. Insulin resistance and Type 2 diabetes not only accelerate the histological and clinical progression of chronic hepatitis C, but also reduce the virological response to IFN-α-based therapy. Thus, understanding the mechanisms underlying HCV-associated glucose metabolism derangements is of paramount interest in order to improve the clinical management of chronic hepatitis C. This article will focus on the studies that consistently argue in favor of an interrelation between HCV and insulin resistance and will highlight the latest discoveries in this field.

Meta-analysis: insulin resistance and sustained virological response in hepatitis C

BACKGROUND

A higher baseline homeostasis model assessment of insulin resistance (HOMA-IR) score has sometimes predicted a poorer sustained virological response (SVR) rate to peginterferon/ribavirin therapy in treatment-naïve chronic hepatitis C patients.

AIM

To perform a meta-analysis to evaluate the impact of HOMA-IR on SVR in hepatitis C.

METHODS

Relevant studies were identified by searching Medline and EMBASE. We identified 17 publications that addressed the influence of insulin resistance on SVR. The random effect model of Der Simonian and Laird method were used for heterogeneous studies using the Meta-Disc software 1.4, Madrid, Spain.

RESULTS

Normal insulin sensitivity was associated with a higher rate of SVR [odds ratio (OR) 2.86 (95%CI: 1.97-4.16)] in comparison with insulin resistance. Moreover, in separate analysis by genotype selecting studies that used HOMA-IR > 2 as cut-off defining insulin resistance, SVR was higher in patients with HOMA-IR < 2 in all genotypes: HCV-1 [OR: 2.16 (95%CI: 1.51-3.08)], HCV-2&3 [OR: 3.06 (95%CI: 1.06-8.82)] and HCV-4 [OR: 6.65(95%CI: 2.51-17.61)]. Studies reporting no association between HOMA and SVR included easy-to-cure cohorts, analysed variables strongly related with insulin resistance like body mass index, steatosis, hyper γGT, age and fibrosis and reported differences in handling and interpretation of HOMA-IR.

CONCLUSION

Elevated HOMA-IR was associated with a lower cure rate of patients with hepatitis C treated with Peg-IFN-α/ribavirin irrespective of genotype, and the more difficult-to-treat cohort, the better the HOMA-IR prediction. HOMA-IR is, as a surrogate marker of insulin resistance, susceptible to some biases derived from both handling and interpretation.

The homeostasis model assessment of the insulin resistance score is not predictive of a sustained virological response in chronic hepatitis C patients

OBJECTIVES

To investigate the independent association between the homeostasis model assessment of the insulin resistance (HOMA-IR) score and rapid virological response (RVR) and sustained virological response (SVR) in chronic hepatitis C (CHC).

METHODS

Observational prospective cohort study of 412 CHC patients [59% males; mean age 45 years; genotype 1 (44%), 2 (32%), 3 (19%) and 4 (5%)] treated with pegylated interferon α plus ribavirin.

RESULTS

A HOMA-IR ≥2.0 was present in 49% and a metabolic syndrome in 4% of patients. By multivariate analysis, independent predictors of SVR were the lack of advanced fibrosis (≥F3) in genotype 1 and a lower body mass index in genotype 3 patients. In the subgroup of patients in whom HCV-RNA was evaluated at week 4 (n = 281), independent predictors of RVR were HCV-RNA <700,000 IU/ml, age <40 years and lower aspartate aminotransferase:alanine aminotransferase ratio in genotype 1 and baseline HOMA-IR ≤2 in genotype 3 patients. No predictive factor of RVR was identified among genotype 2 patients. RVR was the strongest predictor of SVR among genotype 1 or 3 patients.

CONCLUSIONS

In this series of treatment-naïve, Caucasian CHC patients at a low risk for the metabolic syndrome, HOMA-IR is not a predictor of SVR, irrespective of the HCV genotype, although it may predict RVR in genotype 3 infection.

Hepatic steatosis and hepatitis C: Still unhappy bedfellows?

Hepatic steatosis is commonly seen in patients with chronic hepatitis C virus (HCV) infection, and the prevalence is much higher prevalence than in the general population or in patients with chronic hepatitis B. Hepatic steatosis in patients with chronic hepatitis C can be due to alcohol consumption and host metabolic factors such as high body mass index (BMI), obesity, hyperlipidemia, metabolic syndrome and diabetes mellitus in which insulin resistance plays an important role. However, in genotype 3 HCV infection, hepatic steatosis can result from direct viral cytopathic effect. Demographic and clinical characteristics associated with hepatic steatosis in patients with chronic hepatitis C including older age, higher BMI, more genotype 3 infection, and higher mean serum levels of triglyceride, alanine aminotransferase and γ-glutamyl transpeptidase. The clinical relevance of hepatic steatosis in patients with chronic hepatitis C includes a close correlation with hepatic fibrosis, and a poor response to combination peginterferon and ribavirin treatment. In addition, hepatic steatosis has been reported to associate with increased frequency of hepatocellular carcinoma in patients with chronic HCV infection. Whether life style modification such as weight reduction or adding an insulin resistance reducing agent such as metformin or thiazolidinediones combined with current standard peginterferon plus ribavirin treatment will benefit to the chronic hepatitis C patients with hepatic steatosis deserves further evaluation.

Hepatitis C and hepatic steatosis

Hepatic steatosis is commonly seen in patients with chronic hepatitis C infection, and the two together have a greater association than by chance alone. Hepatitis C virus is closely associated with lipid metabolism throughout its lifecycle. Hepatic steatosis is more common in genotype 3 infection, due to direct viral effects including through microsomal triglyceride transfer protein, peroxisome proliferator activating receptor, and sterol regulatory element binding protein. In non-genotype 3 infection, hepatic steatosis is considered largely to be due to alterations in host metabolism, particularly through insulin resistance. The clinical relevance of this association has yet to be fully explored. Hepatic steatosis is associated with increased hepatic fibrosis and a reduced level of sustained virological response to pegylated interferon and ribavirin. Small studies trialing adjuvant anti-diabetic therapies or HMG-CoA reductase inhibitors with pegylated-interferon and ribavirin have shown an improved sustained virological response and reduced viral titer. Furthermore, simple lifestyle alterations showed positive effects on parameters of disease activity. These insights raise the possibility of novel treatment options.

[Hepatitis C and metabolic syndrome]

Insulin resistance is a predictive factor of response to treatment with peginterferon and ribavirin in patients with hepatitis C. Insulin resistance impairs sensitivity to interferon and can block its intracellular signalling. Insulin resistance also induces the development of steatosis, progression of fibrosis and proinflammatory cytokine release and reduces the bioavailability of interferon. Suppressor of cytokine signalling 3 and protein tyrosine phosphatases are involved in blocking the intracellular signalling of interferon and insulin. Insulin resistance can be treated through diet, physical exercise and the use of insulin-sensitizing agents such as biguanides or glitazones. The TRIC-1 study demonstrated that adding metformin to routine treatment improves the possibilities of cure in women and in patients whose insulin sensitivity returns to normal during treatment.

Prolonged treatment with pegylated interferon alpha 2b plus ribavirin improves sustained virological response in chronic hepatitis C genotype 1 patients with late response in a clinical real-life setting in Japan

AIM

This study was conducted to clarify the factors related to sustained virological response (SVR) to pegylated interferon alpha 2b (PEG-IFN) plus ribavirin (RBV) combination therapy administered for 48 weeks in patients with chronic hepatitis C virus (CHCV) and to evaluate the usefulness of prolonged treatment in patients with late virological response (LVR).

METHODS

Of 2257 patients registered at 68 institutions, those with genotype 1 and high viral load were selected to participate in two studies. Study 1 (standard 48-week group, n = 1480) investigated SVR-determining factors in patients who received the treatment for </=52 weeks, whereas study 2 compared SVR rates between patients with LVR who received treatment for either 36-52 weeks (48-week group, n = 223) or 60-76 weeks (72-week group, n = 73).

RESULTS

In study 1, SVR rate was 44.9%; that in male subjects (50.4%) was significantly (P < 0.0001) higher than in female subjects (36.4%). SVR rate significantly (P < 0.0001) decreased with 10-year age increments in both sexes. Multivariate logistic regression analysis revealed that age, F score, platelet count, and HCV load were SVR-related factors. In study 2, SVR rate in the 72-week group (67.1%) was significantly (P = 0.0020) higher than in the 48-week group (46.2%).

CONCLUSIONS

Patients with CHCV genotype 1 infection should be treated with PEG-IFN plus ribavirin combination therapy as early as possible, and 72 weeks' treatment is recommended in patients with LVR regardless of age.

Induction pegylated interferon alfa-2b in combination with ribavirin in patients with genotypes 1 and 4 chronic hepatitis C: a prospective, randomized, multicenter, open-label study

BACKGROUND & AIMS

Standard of care (SOC) treatment for chronic hepatitis C (CHC) involves weekly pegylated (PEG) interferon plus weight-based ribavirin with resultant sustained virologic response (SVR) rates at or near 50% for genotypes 1 and 4 virus. Induction therapy with higher doses of PEG interferon may improve first-phase viral kinetics and thus improve the overall SVR in genotypes 1 and 4 patients.

METHODS

This multicenter, randomized, open-label trial enrolled treatment-naive genotypes 1- and 4-infected CHC patients to either initial induction therapy versus SOC. The induction group received PEG interferon alfa-2b 3.0 mcg/kg/wk for 12 weeks followed by PEG interferon alfa-2b 1.5 mcg/kg/wk for 36 weeks and 13 +/- 2 mg/kg ribavirin daily for 48 weeks. SOC patients received PEG interferon alfa-2b 1.5 mcg/kg weekly for 48 weeks and 13 +/- 2 mg/kg ribavirin daily for 48 weeks. The primary end point was SVR.

RESULTS

There were 610 patients enrolled throughout the United States. Complete early virologic response was 62.6% versus 57.7% in induction versus SOC (NS). Overall SVR was 32% in induction versus 29% in SOC group (NS). Dose reduction of either PEG interferon (24.1% vs 23.8%) or ribavirin (26.8% vs 25.1%) was similar between the 2 groups. There was a trend toward a significant difference when comparing the SVR in induction therapy in patients weighing more than 85 kg versus those receiving SOC (38% vs 28%; P = .08).

CONCLUSIONS

Induction therapy does not enhance complete early virologic response or SVR rates in a predominantly genotype 1 CHC population compared with SOC therapy.

Hepatitis C comorbidities affecting the course and response to therapy

Several studies have demonstrated that the outcome of chronic hepatitis C (CHC) infection is profoundly influenced by a variety of comorbidities. Many of these comorbidities have a significant influence on the response to antiviral therapy. These comorbidities negatively affect the course and outcome of liver disease, often reducing the chance of achieving a sustained virological response with PEGylated interferon and ribavirin treatments. Comorbidities affecting response to antiviral therapy reduce compliance and adherence to inadequate doses of therapy. The most important comorbidities affecting the course of CHC include hepatitis B virus coinfection, metabolic syndrome, and intestinal bacterial overgrowth. Comorbidities affecting the course and response to therapy include schistosomiasis, iron overload, alcohol abuse, and excessive smoking. Comorbidities affecting response to antiviral therapy include depression, anemia, cardiovascular disease, and renal failure.

Impact of obesity, steatosis and insulin resistance on progression and response to therapy of hepatitis C

Clinical progression of chronic hepatitis C depends on several cofactors, which also have a negative affect on the rate of response to interferon-alpha-based therapy. Given the current worldwide prevalence of the metabolic syndrome, the impact of obesity and insulin resistance, and of their histopathological correlate, hepatic steatosis, on the natural history and management of chronic hepatitis C is undoubtedly very important. We will review some of the current knowledge on the clinical consequences of overweight/obesity, steatosis and insulin resistance on chronic hepatitis C, and discuss how this issue may be dealt with in clinical practice.

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.

Hepatitis C virus infection: molecular pathways to steatosis, insulin resistance and oxidative stress

The persistent infection with hepatitis C virus is a major cause of chronic liver disease worldwide. However, the morbidity associated with hepatitis C virus widely varies and depends on several host-related cofactors, such as age, gender, alcohol consumption, body weight, and co-infections. The objective of this review is to discuss three of these cofactors: steatosis, insulin resistance and oxidative stress. Although all may occur independently of HCV, a direct role of HCV infection in their pathogenesis has been reported. This review summarizes the current understanding and potential molecular pathways by which HCV contributes to their development.

Apolipoprotein B-associated cholesterol is a determinant of treatment outcome in patients with chronic hepatitis C virus infection receiving anti-viral agents interferon-alpha and ribavirin

BACKGROUND

Hepatitis C virus (HCV) co-opts very-low-density lipoprotein (VLDL) pathways for replication, secretion and entry into hepatocytes and associates with apolipoprotein B (apoB) in plasma. Each VLDL contains apoB-100 and variable amounts of apolipoproteins E and C, cholesterol and triglycerides.

AIM

To determine whether baseline lipid levels predicted treatment outcome.

METHODS

Retrospective analysis was performed of 250 chronic hepatitis C (CHC) patients who had received anti-viral agents interferon-alpha and ribavirin; 165 had a sustained virological response (SVR). Pre- and post-treatment nonfasting lipid profiles were measured and non-high-density lipoprotein (non-HDL) cholesterol (i.e. apoB-associated) was calculated. Binary logistic regression analysis assessed factors independently associated with treatment outcome.

RESULTS

There was an independent association between higher apoB-associated cholesterol (non-HDL-C) and increased odds of SVR (odds ratio 2.09, P = 0.042). In multivariate analysis, non-HDL-C was significantly lower in HCV genotype 3 (g3) than genotype 1 (P = 0.007); this was reversible upon eradication of HCVg3 (pre-treatment non-HDL-C = 2.8 mmol/L, SVR = 3.6 mmol/L, P < 0.001).

CONCLUSIONS

Higher apoB-associated cholesterol is positively associated with treatment outcome in CHC patients receiving anti-viral therapy, possibly due to competition between apoB-containing lipoproteins and infectious low-density HCV lipo-viral particles for hepatocyte entry via shared lipoprotein receptors.

Amino acid substitutions in the hepatitis C virus core region of genotype 1b are the important predictor of severe insulin resistance in patients without cirrhosis and diabetes mellitus

Previous studies provided a direct experimental evidence for the contribution of HCV core protein in the development of insulin resistance (IR), but the clinical impact of HCV core region on IR is still not clear. The present study evaluated the impact of Amino acid (aa) substitutions of HCV-1b core region on IR in 123 Japanese patients infected with HCV-1b without cirrhosis and diabetes mellitus, and investigated the treatment efficacy of 48-week pegylated interferon (PEG-IFN) plus ribavirin (RBV) according to HOMA-IR values. Patients with IR (HOMA-IR > or = 2.5) and severe IR (HOMA-IR > or = 3.5) were present in 51.2% and 27.6%, respectively. Multivariate analysis identified body mass index (> or = 25 kg/m(2)) and hepatocyte steatosis (> or = 5%) as significant determinants of IR. Furthermore, multivariate analysis identified hepatocyte steatosis (> or = 5%), aa substitutions of the core region (Gln70 (His70) and/or Met91), and age (> or = 55 years) as significant determinants of severe IR. Especially, significantly lower proportions of patients with Gln70 (His70) and/or Met91 were noted among those without severe IR (59.6%) than those with severe IR (82.4%). The rates of sustained virological response in patients with IR (50.0%) were not significantly different from those without IR (52.9%). Furthermore, the rates of non-virological response in patients with IR (28.9%) were not significantly also different from those without IR (20.6%). In conclusion, the present study indicated that substitutions of HCV-1b core region were the important predictor of severe IR in patients without cirrhosis and diabetes mellitus, but HOMA-IR values might be not useful as predictors of 48-week PEG-IFN plus RBV therapy.

Hepatitis C virus and type 2 diabetes

This review focuses on the relationship between hepatitis C virus (HCV) infection and glucose metabolism derangements. Cross-sectional and longitudinal studies have shown that the chronic HCV infection is associated with an increased risk of developing insulin resistance (IR) and type 2 diabetes (T2D). The direct effect of HCV on the insulin signaling has been analyzed in experimental models. Although currently available data should be considered as preliminary, HCV seems to affect glucose metabolism via mechanisms that involve cellular pathways that have been implicated in the host innate immune response. IR and T2D not only accelerate the histological and clinical progression of chronic hepatitis C, but also reduce the early and sustained virological response to interferon-alpha-based therapy. Thus, a detailed knowledge of the mechanisms underlying the HCV-associated glucose metabolism derangements is warranted, in order to improve the clinical management of chronic hepatitis C patients.

What are the comorbidities influencing the management of patients and the response to therapy in chronic hepatitis C?

The natural history of chronic hepatitis C has been defined in several retrospective and prospective studies conducted in the last 20 years. These studies have clearly demonstrated that the outcome of chronic hepatitis C virus infection is profoundly influenced by a variety of cofactors and comorbidities. Many of the cofactors that affect the course of liver disease in hepatitis C also have a significant influence on the result of antiviral therapy. Unfortunately, comorbidities that have been shown to negatively influence the course and outcome of liver disease often reduce the chance of achieving a sustained virological response with pegylated interferon (PEG-IFN) and ribavirin treatment. The most important and frequent comorbidity influencing the course of chronic hepatitis C and the response to antiviral therapy is represented by the metabolic syndrome, and by the associated state of insulin resistance. Other comorbidities that have a negative influence on the progression of hepatitis C and on the response to antiviral therapy include excess alcohol intake, human immunodeficiency virus and hepatitis B virus co-infection and a number of conditions that reduce the benefit of therapy by affecting negatively compliance and/or adherence to adequate PEG-IFN or ribavirin doses.