Obesity and its nurturing effect on hepatitis C

Insulin resistance as a predictor of early virologic response to HCV therapy among chronic HCV Egyptian patients

Prior assessment of insulin resistance by HOMA-IR is emerging as an important milestone in the treatment of patients with chronic hepatitis C. This cost-effective tool is recommended to individualize treatment duration, or to exclude those with low insulin sensitivity from being treated until ameliorating their state of insulin resistance (IR). The present work aims to elucidate further the effect IR state on early viral kinetic response to Chronic hepatitis C virus (HCV) therapy and the impact of HCV treatment and viral eradication on insulin sensitivity. Insulin sensitivity was assessed using the HOMA-IR method. All enrolled patients were treated with a dual therapy (pegylated interferon-alpha plus ribavirin) for 48 weeks and evaluated using qRT-PCR for early virologic response as well as the impact of treatment on insulin sensitivity throughout the early period of therapy. Of a total 392 chronic HCV cases, early virologic response was achieved by 318 (81.1%). IR was detected in 241 (61.5%) chronic HCV patient of which 73.4% responded to treatment. Early virologic response among patients with > 2.18 HOMA-IR value were significantly lower than those with HOMA-IR values ≤2.18 (P < 0.0001). IR was significantly associated with high baseline BMI. Steatosis and fibrosis correlated with IR but neither independently predicted early virologic response. Pretreatment IR < 2.18, low fasting blood glucose, low and intermediate HCV viral load, normal BMI, and non-smoking were independent factors associated with early virologic response. IR interferes with early virologic response to the antiviral care. Clinical application of pretreatment HOMA-IR assessment could help in predicting early treatment outcome and thus enable treatment regimens to be optimized and individually tailored.

Hepatitis C and metabolic syndrome

Hepatitis C virus (HCV) and the hepatic manifestation of metabolic syndrome, nonalcoholic fatty liver disease, are the two major causes of chronic liver disease worldwide. Liver histology of both diseases can be associated with steatosis, oxidative stress and fibrogenesis. Although better defined for HCV, approximately 20% of patients with these diseases can also develop cirrhosis or hepatocellular carcinoma. In recent years, it has become clear that the presence of metabolic syndrome and nonalcoholic fatty liver disease negatively impacts HCV-related outcomes, while simultaneously, the progression of HCV may have metabolic consequences in that it encourages or exacerbates insulin resistance. A growing body of evidence suggests that successful treatment of HCV may rely on understanding and addressing the complex and often mutually confounding relationship between HCV and the individual elements that comprise metabolic syndrome.

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.

Metabolic syndrome, non-alcoholic fatty liver disease and hepatitis C virus: impact on disease progression and treatment response

Non-alcoholic fatty liver disease (NAFLD), a spectrum of liver disease ranging from simple steatosis to non-alcoholic steatohepatitis, is increasingly recognized as the hepatic manifestation of metabolic syndrome and is an important cause of liver-related morbidity and mortality. It is among the most common forms of liver disease. NAFLD reflects abnormal partitioning of fat, such that fat deposition is increased in the liver, and provides a link between NAFLD and the metabolic syndrome, a constellation of metabolic disorders that can also be associated with visceral fat or central adiposity. Together, the features of the metabolic syndrome presage overt diabetes and increase cardiovascular risk. Hepatitis C virus (HCV) appears to exacerbate the metabolic syndrome by eliciting increased insulin resistance (IR) and promoting truncal obesity. Moreover, the concomitant presence of HCV and NAFLD is associated with an increased likelihood of diabetes, hypertension and/or hypertriglyceridaemia. Metabolic abnormalities have been shown to influence response to treatment such that the presence of IR or obesity reduces the likelihood of a sustained virological response (SVR); conversely, SVR has been demonstrated to ameliorate IR and improve beta-cell function. Clinically, these data suggest that attention must be paid not only to optimizing antiviral response but also to screening for and treatment of the various components of the metabolic syndrome.

Hepatic steatosis: A benign disease or a silent killer

Steatosis is a common feature of many liver diseases, namely non-alcoholic steatohepatitis (NASH) and hepatitis C virus (HCV) infection, but the pathogenic mechanisms differ. Insulin resistance (IR), a key feature of metabolic syndrome, is crucial for NASH development, associated with many underlying genetically determined or acquired mitochondrial and metabolic defects and culminates to inflammation and progression to fibrosis. This may have potential implications for new drug therapy. In HCV-related disease, steatosis impacts both fibrosis progression and response to treatment. Steatosis in HCV-related disease relates to both viral factors (HCV genotype 3), and host factors (alcohol consumption, overweight, hyperlipidemia, diabetes). Among others, IR is a recognized factor. Hepatic steatosis is reported to be associated with disturbance in the signaling cascade of interferon and downregulation of its receptors. Thus, hepatic steatosis should not be considered a benign feature, but rather a silent killer.

Morphological changes in intracellular lipid droplets induced by different hepatitis C virus genotype core sequences and relationship with steatosis

Hepatocellular steatosis is common in patients with chronic hepatitis C. Steatosis can be considered as a true cytopathic lesion induced by hepatitis C virus (HCV) genotype 3, suggesting that one or more viral proteins produced during genotype 3 infection are involved in the steatogenic process, while the same proteins produced during infection by other genotypes are not. We examined in vitro interactions between lipid droplets and full-length core protein isolated from patients with HCV genotype 3a infection, with and without steatosis, and from steatosis-free patients infected by HCV genotype 1b. We also examined morphological changes in the lipid droplets according to the HCV genotype and the presence of steatosis in vivo. Core protein processing by signal peptide peptidase was not affected by sequence differences between the variants. We showed that the core protein of both HCV genotypes 1b and 3a binds tightly to the surface of intracellular lipid droplets. However, cells transfected with genotype 3a contain more neutral lipids in lipid droplets, and more large lipid droplets, than cells transfected with genotype 1b sequences. This suggests that HCV core protein-lipid droplet interaction could play a role in virus-induced steatosis. Importantly, we found no genetic or functional differences between genotype 3a core proteins from patients with and without HCV-induced steatosis.

CONCLUSION

This suggests that other viral proteins and/or host factors are involved in the development of hepatocellular steatosis in patients infected by HCV genotype 3a.

Dysmetabolic changes associated with HCV: a distinct syndrome?

Although not associated with the metabolic syndrome, HCV is linked with impaired insulin signalling, insulin resistance, hypocholesterolemia and steatosis which represent a distinct HCV-associated dysmetabolic syndrome. Insulin resistance affects the development of diabetes, fibrosis, impaired response to antivirals and perhaps hepatocellular carcinoma risk. HCV infection is associated with hypocholesterolemia and steatosis reversible after sustained virologic response. A "viral", and a "metabolic" steatosis exist as function of viral genotypes. Little is known about the possible role of HCV in further components of the metabolic syndrome such as atherosclerosis, obesity, arterial hypertension, hyperuricemia and thrombotic risk factors.

Baseline cholesterol is associated with the response to antiviral therapy in chronic hepatitis C

BACKGROUND

Hepatitis C virus (HCV) partially interacts with low-density lipoprotein (LDL) receptors, suggesting a role for lipids in regulating HCV clearance. Our aim was to study if baseline lipids can discriminate responders from non-responders among patients with HCV infection.

METHODS

A total of 109 HCV patients were studied. Laboratory measurements included serum lipids, aminotransferases and viral load, as well as HCV genotype determinations.

RESULTS

Responders (n = 53) had significantly higher serum baseline levels of total cholesterol, LDL cholesterol and apolipoprotein B compared to non-responders (n = 56). Multivariate logistic regression analysis showed that a 10 mg/dL increase in total cholesterol was associated with 3.02 higher odds of responding to treatment (95% CI 1.74-5.32, P < 0.001), while a 10 mg/dL increase in apolipoprotein B levels was associated with 1.81 higher odds of responding to treatment (95% CI 1.37-2.54, P < 0.001), after adjustment for age, sex, body mass index (BMI), smoking habits, baseline viral load, liver histology and administration of pegylated interferon. An inverse association between BMI and response to treatment was also evident (adjusted odds ratio 0.73, 95% CI 0.55-0.96; P = 0.03).

CONCLUSION

Baseline serum total cholesterol levels and BMI could be helpful in discriminating responders to antiviral therapy among patients with HCV infection.

Obesity is an independent risk factor for hepatocellular carcinoma development in chronic hepatitis C patients

BACKGROUND & AIMS

It is not fully elucidated whether obesity enhances hepatocarcinogenesis in patients with chronic hepatitis C. The aim of this study was to investigate the relationship between body weight and risk of hepatocarcinogenesis in chronic hepatitis C patients.

METHODS

We enrolled 1431 patients with chronic hepatitis C who visited our liver clinic between 1994 and 2004, excluding those with hepatocellular carcinoma (HCC) at their visit or with a previous history of HCC. They were divided into 4 groups according to body mass index (BMI): underweight (< or =18.5 kg/m(2), N = 112); normal (18.5 to less than 25 kg/m(2), N = 1023); overweight (25 to less than 30 kg/m(2), N = 265); and obese (>30 kg/m(2), N = 31). We assessed the impact of obesity on the hepatocarcinogenesis adjusted by multivariate Cox proportional hazard regression with other risk factors found significant in univariate analysis.

RESULTS

During the follow-up period (mean, 6.1 y), HCC developed in 340 patients, showing cumulative incidence rates of 10.5%, 19.7%, and 36.8% at 3, 5, and 10 years, respectively. The incidence differed significantly among the BMI groups (P = .007). Adjusting for other significant factors, overweight and obesity were shown to be an independent risk factor of HCC, with a hazard ratio of 1.86 (95% confidence interval, 1.09-3.16; P = .022) and 3.10 (95% confidence interval, 1.41-6.81; P = .005) as compared with the underweight patients.

CONCLUSIONS

The risk of HCC in patients with chronic hepatitis C increases in proportion to BMI in a wide range of its values, from underweight to obese.

Malnutrition and infection: an update

The original Scrimshaw, Taylor and Gordon conceptual framework for the interaction of nutrition and infection has well served the scientific community for almost half a century. At its core is the notion of synergistic (mutually reinforcing) and antagonistic (mutually nullifying) influences of the malnourished state on infectious conditions and vice versa. Research on a series of advancing fronts, however, has allowed the incorporation of both relevant public health issues (parasitosis, emerging infectious diseases, obesity and overweight, etc.) and advancing science (molecular immunology, oxidation biology, multiple micronutrient deficiencies, etc.). The present review is an interpretative update on close to 50 years of demographic and epidemiological evolution in the field of human nutrition and the implications for the interaction in the context of microbiological and immunological developments on the infectious side of the dialectic.

Insulin resistance and response to therapy in patients infected with chronic hepatitis C virus genotypes 2 and 3

BACKGROUND/AIMS

Obesity is associated with impaired treatment responses in chronic hepatitis C. The aim of this study was to determine the relationship between the insulin resistance frequently seen in obese subjects and sustained virological response to anti-viral therapy (SVR) in patients with genotype 2 or 3 infection.

METHODS

Eighty-two patients were studied; 59 received interferon/ribavirin while 23 received peg-interferon/ribavirin.

RESULTS

The overall SVR was (77%). Patients with a SVR had lower mean serum insulin (10.7+/-0.8 microU/ml vs. 22.2+/-4.9; P = 0.03), fibrosis stage (1.9+/-0.1 vs. 2.7+/-0.3; P = 0.007) and insulin resistance measured by the homeostasis model (HOMA-IR) (2.5+/-0.2 vs. 6.1+/-1.5; P = 0.03). Age, gender, ethnicity, alcohol consumption, treatment regimen, viral load, portal activity and steatosis did not influence the SVR. By linear regression, body mass index (P < 0.001) and fibrosis stage (P < 0.001) were independently associated with HOMA-IR. After adjusting for fibrosis stage, patients with HOMA-IR of < 2 were 6.5 times more likely to achieve SVR than those with HOMA-IR > or = 2.

CONCLUSIONS

Even in treatment-responsive genotypes 2 and 3, high HOMA-IR is associated with a reduced response. Improving insulin sensitivity may be a useful adjunct to anti-viral therapy in these individuals.

Hepatitis C and steatosis

Hepatitis C infection and non-alcohol-related hepatic steatosis are the most common liver diseases worldwide, and both conditions often co-exist in the same patient. Hepatitis C virus (HCV) genotype 3 directly induces development of steatosis, whereas in patients with non-genotype 3 chronic hepatitis C infection, insulin resistance plays a key role in the pathophysiology of steatosis. Insulin resistance and its clinical components including obesity, hyperglycemia, hypertriglyceridemia, increased blood pressure, and low HDL-cholesterol levels are often seen in patients with chronic hepatitis C infection. Both increased adipocity and presence of steatosis may increase the risk of fibrosis progression, and both have been associated with a decreased rate of response to antiviral treatment. Hence, liver steatosis in the setting of HCV infection is a distinct condition with specific clinical and prognostic implications. Accumulating evidence suggests that weight management may lead not only to a decrease in steatosis but also improvement in fibrosis severity. However, further studies are necessary to determine whether weight reduction improves response to antiviral therapy.

A multivariable model of clinical variables predicts advanced fibrosis in chronic hepatitis C

BACKGROUND

A noninvasive method to identify advanced hepatic fibrosis (AHF) in chronic hepatitis C (CHC) could preclude the need for routine liver biopsy. Recent evidence suggests that obesity may contribute to hepatic fibrosis in hepatitis C virus infection.

GOALS

To determine whether clinical variables, including body mass index (BMI), can predict risk of AHF.

STUDY

Retrospective review of untreated CHC patients evaluated between 1993 and 2002 without clinical or physical evidence of end-stage liver disease. Liver biopsies were scored for fibrosis, steatosis, and inflammation. Multivariable analysis was used to derive and internally validate a prediction equation. A clinical index was created from the equation by assigning points for each variable. The risk of AHF was measured for each risk category.

RESULTS

Two hundred eighty-six satisfied inclusion criteria, of which 86 (30%) had AHF. In the derivation subgroup (N=190), 5 factors were independently associated with AHF: diabetes mellitus, platelets count <150,000, aspartate aminotransferase > or =65 IU/mL, international normalized ratio > or =1.1, and bilirubin > or =0.85 mg/dL. The corresponding risk index contained 3 categories: low-risk (score of 0), intermediate risk (scores of 1 to 3), and high risk (scores of > or =4), in which the respective risks of AHF were 9%, 34%, and 92%. Inclusion of BMI did not improve model performance.

CONCLUSIONS

A model for estimating AHF risk in CHC performed well in this population. BMI had no effect on the risk of AHF. If this model can be validated in other patient cohorts, it could preclude the need for liver biopsy in patients with scores of 0 or > or =4.

Impact of obesity on treatment of chronic hepatitis C

Obesity and the metabolic syndrome have hepatic manifestations, including steatosis and progression of fibrosis. In individuals with chronic hepatitis C, obesity is associated with inflammation, insulin resistance, steatosis, progression of fibrosis, and nonresponse to treatment with interferon or peginterferon alpha and ribavirin. Patients with both hepatitis C and obesity-related nonalcoholic fatty liver disease are at greater risk for more advanced liver disease. We review the mechanisms by which obesity may be associated with decreased efficacy of interferon-based therapies in individuals with chronic hepatitis C and the therapeutic strategies that may increase the effectiveness of these therapies in obese individuals.

Hepatitis C and steatosis: a reappraisal

The overall prevalence of steatosis in patients with Hepatitis C virus (HCV) chronic infection is 55.5% (range 34.8-81.2%). This is a two to threefold increase compared with the prevalence of steatosis in chronic hepatitides because of other aetiologies and of the figures expected on the grounds of a steatosis-HCV chance association. HCV genotype 3 (HCV-3) has specific epidemiological features; furthermore, as compared with HCV-non-3 genotypes, it is associated with a higher prevalence (74.1%vs 47.9%, P < 0.01) and with more severe grades of steatosis (prevalence of grade 3 steatosis 29.6 vs 5.5 P < 0.01). Host and viral factors play a role, although to a variable extent, in the pathogenesis of HCV-3 and non-3 steatosis. HCV load and body mass index are associated with steatosis in HCV-3 and in HCV-non-3 patients respectively. Serum cholesterol levels and liver steatosis at baseline follow an inverse relationship in HCV infection. As hypocholesterolaemia corrects only in those sustained responders to antiviral treatment both in genotype 3 and in non-3 genotypes, the occurrence of a virally induced, acquired and reversible hypobetalipoproteinaemia seems plausible. Steatosis affects the natural course of HCV infection: it is associated with fibrosis, a possible mediator of increased risk to develop type 2 diabetes, it impairs the response to antiviral treatment in HCV-3 patients and might constitute a risk factor for the development of hepatocellular carcinoma. These observations indicate the need to evaluate the efficacy of combined antiviral and 'metabolic' approaches vs standard antiviral regimes in patients with steatosis and HCV chronic infection.

The impact of competing risks on the observed rate of chronic hepatitis C progression

BACKGROUND & AIMS

In previous studies about the natural history of chronic hepatitis C (CHC), age at the time of infection correlated with the rate at which hepatic fibrosis progresses. The presence of a competing risk, namely higher mortality from natural causes, may contribute to this observation. A simulation experiment was conducted to measure the magnitude of the effect of competing risks on the observed rate of fibrosis progression of CHC.

METHODS

A computer-based probabilistic model was created in which fibrosis of CHC progressed from stage 0 to 4 (cirrhosis) in 20-year-old and 50-year-old male and female cohorts. The rate of fibrosis progression was randomly assigned to each simulated individual from a distribution common to all age- and sex-specific cohorts. The cohorts also experienced mortality from natural causes according to the 2000 census data.

RESULTS

The observed median time to reach cirrhosis for the 50-year-old cohorts was 20.4 +/- 0.2 years compared with 29.7 +/- 0.2 for the 20-year-old cohorts ( P < 0.01). The median time to reach cirrhosis in men was 24.2 +/- 0.6 years compared with 25.9 +/- 0.6 in women ( P = 0.01). Overall, the observed rate of progression was slowest among young women. Similarly, accelerating mortality from natural causes, simulating the impact of comorbid conditions that shorten survival, reduced the observed time to reach cirrhosis.

CONCLUSIONS

Even if the underlying rate of fibrosis progression in CHC was held constant, the time to reach cirrhosis will be observed to be substantially shorter in subjects with a higher competing mortality.

The clinical features, diagnosis and natural history of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most common chronic liver disease in the United States. The histologic spectrum of NAFLD ranges from steatosis liver alone to nonalcoholic steatohepatitis (NASH), which is the most serious form of NAFLD. NASH is a progressive fibrotic disease, in which cirrhosis and liver-related death occur in up to 20% and 12%, respectively, over a 10-year period. NASH-associated cirrhosis also can develop into subacute liver failure, progress to hepatocellular carcinoma, and reoccur post-transplantation. In contrast, steatosis alone has a more benign clinical course, although progression to cirrhosis has occurred in 3% of these patients. The major risk factors for fibrosis include diabetes or obesity, an aspartate aminotransferase/alanine aminotransferase ratio of greater than 1, age older than 50, and hepatic histology.

Steatosis and liver cell apoptosis in chronic hepatitis C: a mechanism for increased liver injury

Steatosis is increasingly recognized as a cofactor influencing the progression of fibrosis in chronic hepatitis C; however, the mechanisms by which it contributes to liver injury remain uncertain. We studied 125 patients with chronic hepatitis C to assess the effect of steatosis on liver cell apoptosis and the expression of Bcl-2, Bcl-x(L), Bax, and tumor necrosis factor alpha (TNF-alpha) and the relationship between liver cell apoptosis and disease severity. A significant increase in liver cell apoptosis was seen in liver sections with increasing grade of steatosis (r = 0.42; P <.0001). Hepatic steatosis and previous heavy alcohol consumption were the only two variables independently associated with the apoptotic index. Increasing steatosis was associated with decreased Bcl-2 mRNA levels and an increase in the proapoptotic Bax/Bcl-2 ratio (r = -0.32, P =.007; and r = 0.27, P =.02, respectively). In the absence of steatosis, increased liver cell apoptosis was not associated with stellate cell activation or fibrosis (r = 0.26, P =.11; r = 0.06, P =.71, respectively). In contrast, in the presence of steatosis, increasing apoptosis was associated with activation of stellate cells and increased stage of fibrosis (r = 0.35, P =.047; r = 0.33, P =.03, respectively), supporting the premise that the steatotic liver is more vulnerable to liver injury. In patients with hepatitis C virus genotype 3, there was a significant correlation between TNF-alpha mRNA levels and active caspase-3 (r = 0.54, P =.007). In conclusion, these observations suggest a mechanism whereby steatosis contributes to the progression of liver injury in chronic hepatitis C. Further investigation will be required to determine the molecular pathways responsible for the proapoptotic effect of steatosis and whether this increase in apoptosis contributes directly to fibrogenesis.

Host factors and failure of interferon-alpha treatment in hepatitis C virus

Failure of interferon-alpha (IFN-alpha) treatment in patients with chronic hepatitis C virus (HCV) infection is a challenging obstacle for clinical and experimental hepatology. Both viral and host factors have been implicated in reducing responsiveness to IFN-alpha therapy. The role of viral factors has been studied extensively and has been summarized in several review articles; however, much less attention has been paid to host factors. In this paper, we review evidence of host factor involvement in IFN-alpha treatment failure. We discuss possible underlying mechanisms responsible for these effects. Potential therapeutic strategies to enhance the effectiveness of IFN-alpha therapy for HCV are also proposed.

Fat, diabetes, and liver injury in chronic hepatitis C

It is increasingly recognized that host factors can modulate the fibrogenic response in patients with chronic hepatitis C. Obesity, because of its prevalence, and diabetes, which seems to occur more frequently in patients infected by the hepatitis C virus (HCV), are often present in patients with chronic hepatitis C. Both conditions result in fatty liver, which in turn is associated with more severe liver damage, especially fibrosis or inflammation. Steatosis can either originate from associated metabolic alterations (insulin resistance resulting in metabolic steatosis) or from a direct cytopathic effect of the virus (genotype 3, resulting in viral steatosis). Metabolic steatosis seems to be a factor in resistance to antiviral therapy, whereas viral steatosis is reduced in sustained responders. Whether metabolic steatosis has a direct role in liver fibrosis progression or is only a surrogate marker of an underlying defect triggering fibrogenesis, such as insulin resistance, is a subject of debate. High serum glucose levels and diabetes have a strong and independent profibrogenic impact. Exciting new data are expanding our understanding of the mechanisms of steatogenesis in HCV infection and providing potential links between insulin resistance or hyperglycemic states and liver fibrogenesis.