Association between lipoprotein subfraction profile and the response to hepatitis C treatment in Japanese patients with genotype 1b

Impact of Chronic Hepatitis C Virus Genotype 1b Infection on Triglyceride Concentration in Serum Lipoprotein Fractions

Reduced low-density lipoprotein (LDL) cholesterol level is a characteristic feature of dyslipidemia in chronic hepatitis C virus (HCV) infection. However, abnormality in serum triglyceride (TG) has not been fully investigated. To clarify the impact of HCV genotype 1b (G1b) infection and advanced fibrosis on serum TG profiles, TG concentrations in lipoprotein fractions were examined in fasting sera from 185 subjects with active or cleared HCV infection by high-performance liquid chromatography. Serum lipoproteins were fractionated into four classes: chylomicron, very low-density lipoprotein (VLDL), LDL, and high-density lipoprotein (HDL). Then, the significance of HCV G1b infection on TG levels in each lipoprotein fraction was determined using multiple regression models. We found that active HCV G1b infection was positively associated with high HDL-TG levels and low VLDL-TG levels, independent of other factors included in the regression model. In VLDL sub-fractions, active HCV infection was only found to be associated with low levels of large VLDL-TG. Similarly, advanced liver fibrosis in chronic HCV G1b infection was associated with high levels of LDL-TG, HDL-TG, and small VLDL-TG, independent of other clinical factors. These findings indicate that active HCV G1b infection and advanced fibrosis are closely associated with abnormal serum TG profiles.

Hepatitis C virus resistance to interferon therapy: an alarming situation

Hepatitis C virus is presently a major public health problem across the globe. The main objective in treating hepatitis C virus (HCV) infection is to achieve a sustained virological response (SVR). Interferon-α (IFN-α) and pegylated interferon (PegIFN) in combination with Ribavirin (RBV) are the choice of treatment nowadays against chronic hepatitis C. There are several mechanisms evolved by the hepatitis C virus that facilitate the persistence of virus and further lead the patient’s status as non responder. Various factors involved in patient’s lack ofresponse to the therapy include: (1) viral factors, (2) host factors, (3) molecular mechanisms related to the lack of response and (4) social factors. Herein we have made an attempt to summarize all the related predictors of drug resistance in one article so that the future polices can be planned to overcome this obstacle and potential therapies can be designed by considering these factors.

Eradicating hepatitis C virus ameliorates insulin resistance without change in adipose depots

Chronic hepatitis C (CHC) is associated with lipid-related changes and insulin resistance; the latter predicts response to antiviral therapy, liver disease progression and the risk of diabetes. We sought to determine whether insulin sensitivity improves following CHC viral eradication after antiviral therapy and whether this is accompanied by changes in fat depots or adipokine levels. We compared 8 normoglycaemic men with CHC (genotype 1 or 3) before and at least 6 months post viral eradication and 15 hepatitis C antibody negative controls using an intravenous glucose tolerance test and two-step hyperinsulinaemic-euglycaemic clamp with [6,6-(2) H2 ] glucose to assess peripheral and hepatic insulin sensitivity. Magnetic resonance imaging and spectroscopy quantified abdominal fat compartments, liver and intramyocellular lipid. Peripheral insulin sensitivity improved (glucose infusion rate during high-dose insulin increased from 10.1 ± 1.6 to 12 ± 2.1 mg/kg/min/, P = 0.025), with no change in hepatic insulin response following successful viral eradication, without any accompanying change in muscle, liver or abdominal fat depots. There was corresponding improvement in incremental glycaemic response to intravenous glucose (pretreatment: 62.1 ± 8.3 vs post-treatment: 56.1 ± 8.5 mm, P = 0.008). Insulin sensitivity after viral clearance was comparable to matched controls without CHC. Post therapy, liver enzyme levels decreased but, interestingly, levels of glucagon, fatty acid-binding protein and lipocalin-2 remained elevated. Eradication of the hepatitis C virus improves insulin sensitivity without alteration in fat depots, adipokine or glucagon levels, consistent with a direct link of the virus with insulin resistance.

Hepatic triglyceride lipase plays an essential role in changing the lipid metabolism in genotype 1b hepatitis C virus replicon cells and hepatitis C patients

AIM

Recently, several studies have shown the existence of associations between lipoprotein profiles and hepatitis C virus (HCV), although only a limited amount of information is available about the mechanisms underlying the changes in the lipoprotein profiles associated with HCV. In this study, we investigated the association between lipoprotein profile, classified according to the particle size, and lipoprotein metabolism.

METHODS

We used four kinds of cells for this experiment; full-length genome HCV RNA replicon cells (OR6), sub-genomic HCV RNA replicon cells (sO), and OR6c cells and sOc cells, which were the same cell lines treated with interferon-α. The triglyceride (TG) levels in the lipoprotein subclasses of the culture medium were measured by high-performance liquid chromatography. The mRNA expression levels of several molecules associated with lipoprotein metabolism were measured in the OR6, OR6c, sO and sOc cells. To confirm some of the results obtained using the in vitro system, liver biopsy samples obtained from the patients were also examined.

RESULTS

The content of TG in the large low-density lipoprotein (LDL) and medium LDL in the culture medium was increased only in the OR6 cells. The hepatic triglyceride lipase (HTGL) mRNA expression levels were lower in the OR6 cells than in the OR6c cells (P < 0.01). Examination of the HTGL expression levels in the patients' livers revealed a decrease in HTGL expression in the chronic hepatitis C liver as compared with that in the chronic hepatitis B or non-alcoholic steatohepatitis liver (P < 0.01).

CONCLUSION

We showed that HCV inhibits HTGL production in hepatocytes, inducing a change of the lipoprotein profile.

Serum lipoprotein profiles and response to pegylated interferon plus ribavirin combination therapy in patients with chronic HCV genotype 1b infection

BACKGROUND

Abnormal serum lipid profiles have been noted in patients with chronic hepatitis C virus (HCV) infection. Moreover, many reports suggest that serum lipoprotein profiles are more profoundly distorted in patients with HCV G1b infection who have an unfavorable response to pegylated interferon (peg-IFN) plus ribavirin (RBV) combination therapy. However, after the discovery of single nucleotide polymorphisms near the IL28B gene (rs8099917 and rs12979860) as potent predictive factors affecting the response to peg-IFN plus RBV, lipid factors are thought to be confounding factors.

OBJECTIVES

To re-examine the significance of lipoprotein profiles on virological response to peg-IFN plus RBV combination therapy in patients with chronic HCV G1b infection, we examined cholesterol and triglyceride concentrations in each lipoprotein fraction separated by high performance liquid chromatography.

PATIENTS AND METHODS

Lipoprotein profiles were examined using fasting sera from 108 patients infected with HCV G1b who had chronic hepatitis, as determined by liver biopsy. Results of lipoprotein profiles and clinical data, including IL28B genotype and amino acid substitution at aa70 of HCV G1b, were compared between patients with a sustained virological response (SVR) and non-SVR or a non-virological response (NVR) and virological responses other than NVR (non-NVR). In addition, significant predictive factors independently associated with virological response to peg-IFNα-2b plus RBV were determined by logistic regression analysis.

RESULTS

An increased ratio of cholesterol/triglyceride in very low-density lipoprotein (odds ratio (OR) 3.03; 95% confidence interval (CI) 1.01-9.44) along with a major genotype of rs8099917 (OR 9.09; 95% CI 2.94-33.33), were independent predictive factors for SVR. In contrast, lipid factors were not elucidated as independent predictive factors for NVR.

CONCLUSIONS

Examination of the fasting lipid profile has clinical importance in predicting the efficacy of peg-IFN-α-2b plus RBV combination therapy for patients with HCV G1b even after the discovery of the IL28 genotype as a potent predictive factor.

Serum cholesterol and statin use predict virological response to peginterferon and ribavirin therapy

Elevated low-density lipoprotein (LDL) levels and statin use have been associated with higher sustained virological response (SVR) rates in patients receiving chronic hepatitis C therapy. However, these relationships have not been well characterized in randomized controlled trials. Furthermore, little is known about the relationship between high-density lipoprotein (HDL) and virological response. To determine whether baseline LDL or HDL levels and statin use affect SVR rates, we retrospectively evaluated the IDEAL (Individualized Dosing Efficacy Versus Flat Dosing to Assess Optimal Pegylated Interferon Therapy) trial, in which 3070 treatment-naive, hepatitis C virus (HCV) genotype 1-infected patients were treated for up to 48 weeks in one of the following arms: (1) peginterferon (PEG-IFN) alfa-2b at 1.5 microg/kg/week with ribavirin (RBV) at 800 to 1400 mg/day, (2) PEG-IFN alfa-2b at 1.0 microg/kg/week with RBV at 800 to 1400 mg/day, or (3) PEG-IFN alfa-2a at 180 microg/week with RBV at 1000 to 1200 mg/day. Virological responses were assessed by pretreatment statin use and baseline elevated LDL levels (> or =130 mg/dL) or low HDL levels (<40 mg/dL for men and <50 mg/dL for women). In 1464 patients with baseline elevated LDL levels or low HDL levels, the SVR rate was significantly higher than that in patients with normal levels (44.9% versus 34.0%, P < 0.001). In 66 patients receiving a statin pretreatment, the SVR rate was higher than the rate of those not receiving it (53.0% versus 39.3%, P = 0.02). In a multivariate logistic regression analysis using the stepwise selection method with baseline characteristics, a high LDL level [odds ratio (OR) = 1.6, 95% confidence interval (CI) = 1.4-1.8, P < 0.001], a low HDL level (OR = 0.5, 95% CI = 0.3-0.8, P = 0.004), and statin use (OR = 2.0, 95% CI = 1.1-3.7, P = 0.02) were independently associated with SVR.

CONCLUSION

Baseline elevated LDL levels or low HDL levels and preemptive statin usage were associated with higher SVR rates. Prospective studies may be considered to explore the biological impact of these factors on HCV RNA replication and treatment response.