Hepatic steatosis and insulin resistance are associated with serum imbalance of adiponectin/tumour necrosis factor-alpha in chronic hepatitis C patients

Lipid and carbohydrate parameters in children with chronic hepatitis C

PURPOSE

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

MATERIAL/METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

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

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

Manifestations of chronic hepatitis C virus infection beyond the liver

In addition to its effects in the liver, chronic hepatitis C virus (HCV) infection can have serious consequences for other organ systems. Extrahepatic manifestations include mixed cryoglobulinemia (MC) vasculitis, lymphoproliferative disorders, renal disease, insulin resistance, type 2 diabetes, sicca syndrome, rheumatoid arthritis-like polyarthritis, and autoantibody production; reductions in quality of life involve fatigue, depression, and cognitive impairment. MC vasculitis, certain types of lymphoma, insulin resistance, and cognitive function appear to respond to anti-HCV therapy. However, treatments for HCV and other biopsychosocial factors can reduce quality of life and complicate management. HCV treatment has a high overall cost that increases when extrahepatic manifestations are considered. HCV appears to have a role in the pathogenesis of MC vasculitis, certain types of lymphoma, and insulin resistance. Clinicians who treat patients with HCV infections should be aware of potential extrahepatic manifestations and how these can impact and alter management of their patients.

[New-onset diabetes mellitus and liver transplantation, with special consideration of recurrent hepatitis C]

New-onset diabetes is a common complication after liver transplantation.

AIM

We aimed to analyze the incidence and rate of known risk factors and the impact of new-onset diabetes mellitus on postoperative outcome.

METHODS

We retrospectively evaluated the files of 310 patients who underwent liver transplantation between 1995 and 2009. Definition of new-onset diabetes included: repeated fasting serum glucose >6.8 mmol/l and/or sustained antidiabetic therapy that was present 3 months after transplantation.

RESULTS

New-onset diabetes occurred in 63 patients (20%). Differences between the new-onset and the control group were the donor body mass index (24+/-3 vs. 22.4+/-3.6 kg/m 2 , p = 0.003), donor male gender (58% vs. 33%, p = 0.002), and recipient age (47.6+/-7.2 vs. 38.3+/-14.6 year, p<0.001), body mass index (26.7+/-3.8 vs. 23.3+/-5.6 kg/m 2 , p<0.001), male gender (60% vs. 44%, p = 0.031). The 66% of patients with new-onset diabetes were transplanted with cirrhosis caused by hepatitis C virus infection, while in the control group the rate was 23% (p<0.001). Cumulative patient survival rates at 1, 3, 5 and 8 year were 95%, 90.6%, 88% and 88% in the control group, and 87%, 79%, 79% and 64% in the de novo group, respectively (p = 0.011). Cumulative graft survival rates at 1, 3, 5 and 8 year in the control group were 92%, 87%, 86% and 79%, in the de novo diabetes group the rates were 87%, 79%, 79%, 65%, respectively (p = NS). In case of early recurrence (in 6 months), majority of patients developed new-onset diabetes (74% vs. control 26%, p = 0.03). More patients had more than 10 times higher increase of the postoperative virus titer correlate to the preoperative titer in the de novo diabetes group (53% vs. 20%, p = 0.028). Mean fibrosis score was higher in new-onset group one year after the beginning of antiviral therapy (2.05+/-1.53 vs. 1.00+/-1.08, p = 0.039).

CONCLUSIONS

Risk factors for new-onset diabetes after transplantation are older age, obesity, male gender and cirrhosis due to hepatitis C infection. The early recurrence, viremia and more severe fibrosis after antiviral therapy have an impact on the occurrence of new-onset diabetes in hepatitis C positive patients.

Steatosis as a co-factor in chronic liver diseases

The finding of lipid accumulation in the liver, so-called hepatic steatosis or non-alcoholic fatty liver disease, is a common condition frequently found in healthy subjects. Its prevalence, in fact, has been estimated by magnetic resonance studies to be about 35% in the general population and 75% in obese persons. Nevertheless, its presence generates liver damage only in a small percentage of subjects not affected by other liver diseases. It should be defined as a “co-factor” capable of affecting severity and progression, and also therapeutic perspectives, of liver diseases to which it is associated. Herein we will evaluate the impact of hepatic steatosis and obesity on the most common liver diseases: chronic viral hepatitis C and B, and alcoholic liver disease.

Adiponectin action from head to toe

Adiponectin, the most abundant protein secreted by white adipose tissue, is known for its involvement in obesity-related disorders such as insulin resistance, type 2 diabetes mellitus and atherosclerosis. Moreover, modulation of the circulating adiponectin concentration is observed in pathologies that are more or less obesity-related, such as cancer and rheumatoid arthritis. The wide distribution of adiponectin receptors in various organs and tissues suggests that adiponectin has pleiotropic effects on numerous physiological processes. Besides its well-known insulin-sensitizing, anti-inflammatory and antiatherosclerotic properties, accumulating evidence suggests that adiponectin may also have anticancer properties and be cardioprotective. A beneficial effect of adiponectin on female reproductive function was also suggested. Since adiponectin has numerous beneficial biological functions, its use as a therapeutic agent has been suggested. However, the use of adiponectin or its receptors as therapeutic targets is complicated by the presence of different adiponectin oligomeric isoforms and production sites, by multiple receptors with differing affinities for adiponectin isoforms, and by cell-type-specific effects in different tissues. In this review, we discuss the known and potential roles of adiponectin in various tissues and pathologies. The therapeutic promise of administration of adiponectin and the use of its circulating levels as a diagnostic biomarker are further discussed based on the latest experimental studies.

Serum HCV RNA levels and HCV genotype do not affect insulin resistance in nondiabetic patients with chronic hepatitis C: a multicentre study

BACKGROUND

Chronic hepatitis C (CHC) induces insulin resistance (IR) and subsequently diabetes.

AIM

To examine viral, metabolic and histological predictors of IR in 275 CHC patients to test the hypothesis that IR differs among HCV genotypes and that viral replication directly affects IR.

METHODS

We studied 275 nondiabetic treatment-naïve CHC patients. Histological lesions were evaluated according to Ishak. IR was assessed using homeostasis model assessment for insulin resistance (HOMA-IR).

RESULTS

HOMA > 3.0 was found in 37% of patients, independently associated with higher BMI and GGT. In genotype non-3 patients, HOMA > 3.0 was associated with higher BMI and GGT values, while no significant association was noted in genotype 3 patients. In non-obese patients with minimal fibrosis, HOMA > 3.0 was found in 20% of cases without significant differences among genotypes. No association between HOMA > 3.0 and HCV-RNA levels was found. Severe fibrosis (stage 5-6) related to older age (OR:1.048), HOMA-IR (OR:1.177), necroinflammation (OR: 2.990) and higher ALT (OR: 1.009) and GGT (OR:1.006).

CONCLUSIONS

IR develops at early stages of CHC without significant differences among genotypes. It is more frequent in obese patients with steatosis and contributes to fibrosis progression. However, IR does not seem to be associated with viraemia and therefore its exact pathogenetic mechanism in CHC remains elusive.

Adipokines in liver diseases

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

Elevation of serum gamma-glutamyltranspeptidase activity is frequent in chronic hepatitis C, and is associated with insulin resistance

BACKGROUND AND AIMS

Serum gamma-glutamyltranspeptidase level is often increased in patients with chronic hepatitis C, and we aimed to identify factors associated with this phenomenon in patients completely abstinent from alcohol (teetotaller).

PATIENTS AND METHODS

71 teetotaller patients have been identified by personal history, questioning of relatives, CAGE questionnaire administration and unscheduled alcoholemia measurements.

RESULTS

39 patients (55%) had elevated (>50IU/L) gamma-glutamyltranspeptidase level. Body mass index, insulin and C-peptide level, insulin resistance, piecemeal necrosis score > or =3, fibrosis score > or =2 and steatosis score > or =1 were significantly higher in these patients than in those (n=32) with normal gamma-glutamyltranspeptidase. At multiple linear regression analysis gamma-glutamyltranspeptidase level was associated with C-peptide level, insulin resistance and histopathologic grading. At multiple logistic regression analysis, C-peptide level (OR=2.13) and piecemeal necrosis score > or =3 (OR=4.59) were the only factors independently associated with elevated gamma-glutamyltranspeptidase. Sustained virological response during pegylated interferon plus ribavirine treatment was achieved by 97% and 49% patients with normal and elevated gamma-glutamyltranspeptidase, respectively (p=0.0001).

CONCLUSION

Serum gamma-glutamyltranspeptidase level is often elevated in chronic hepatitis C and is associated with metabolic and inflammatory factors; this phenomenon may contribute to explain and to predict resistance to treatment in this subgroup of patients.

Fenofibrate and PBA prevent fatty acid-induced loss of adiponectin receptor and pAMPK in human hepatoma cells and in hepatitis C virus-induced steatosis

Adiponectin receptors play a key role in steatosis and inflammation; however, very little is known about regulation of adiponectin receptors in liver. Here, we examined the effects of palmitate loading, endoplasmic reticulum (ER) stress, and the hypolipidemic agent fenofibrate on adiponectin receptor R2 (AdipoR2) levels and AMP-activated protein kinase (AMPK) in human hepatoma Huh7 cells and in Huh.8 cells, a model of hepatitis C-induced steatosis. Palmitate treatment reduced AdipoR2 protein and basal AMPK phosphorylation in Huh7 cells. Fenofibrate treatment preserved AdipoR2 and phosphorylated AMPK (pAMPK) levels in palmitate-treated cells accompanied by reduced triglyceride (TG) accumulation and less activation of ER stress markers CCAAT/enhancer binding (C/EBPbeta) and eukaryotic translation initiation factor 2 alpha. ER stress agents thapsigargin and tunicamycin suppressed AdipoR2 and pAMPK levels in Huh7 cells, while fenofibrate and the chemical chaperone 4-phenylbutyrate (PBA) prevented these changes. AdipoR2 levels were lower in Huh.8 cells and fenofibrate treatment increased AdipoR2 while reducing activation of c-Jun N-terminal kinase and C/EBPbeta expression without changing TG levels. Taken together, these results suggest that fatty acids and ER stress reduce AdipoR2 protein and pAMPK levels, while fenofibrate and PBA might be important therapeutic agents to correct lipid- and ER stress-mediated loss of AdipoR2 and pAMPK associated with nonalcoholic steatohepatitis.

Insulin resistance, serum adipokines and risk of fibrosis progression in patients transplanted for hepatitis C

In the nontransplant setting diabetes mellitus is a risk factor for disease progression in patients with chronic hepatitis C virus (HCV) infection. The impact of early insulin resistance on the development of advanced fibrosis, even in the absence of clinically apparent diabetes mellitus, is not known. Our aim was to determine whether the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) can be used to identify insulin-resistant patients at risk for rapid fibrosis progression. Cohort study including patients transplanted for chronic HCV between January 1, 1995 and January 1, 2005. One hundred sixty patients were included; 25 patients (16%) were treated for diabetes mellitus and 36 patients (23%) were prediabetic, defined as HOMA-IR >2.5. Multivariate Cox regression analysis showed that insulin resistance (hazard ratio (HR) 2.07; confidence interval (CI) 1.10-3.91, p = 0.024), donor age (HR 1.33;CI 1.08-1.63, p = 0.007) and aspartate aminotransferase (HR 1.03;CI 1.01-1.05, p < 0.001) were significantly associated with a higher probability of developing advanced fibrosis, i.e. Knodell fibrosis stage 3 or 4, whereas steatosis (HR 0.94;CI 0.46-1.92, p = 0.87) and acute cellular rejection (HR 1.72;CI 0.88-3.36, p = 0.111) were not. In conclusion, posttransplant insulin resistance is strongly associated with more severe recurrence of HCV infection. HOMA-IR is an important tool for the identification of insulin resistance among patients at risk for rapid fibrosis progression after liver transplantation for HCV.

Serum level of adiponectin correlated with gender and genotype in patients with chronic hepatitis C

Adiponectin is well recognized as plasma physiologically active polypeptide hormone exclusively derived from human and animal mature adipocytes, with vigorous property in antidiabetic, antiobesity, antiatherogenic, and anti-inflammatory processes. In this study, we investigated the correlation between serum adiponectin level and clinical and pathological parameters in patients with chronic hepatitis C (CHC). The study included 127 patients with CHC and 42 healthy volunteers as controls whose laboratory parameters and serum adiponectin and tumor necrosis factor-alpha (TNF-alpha) were assessed using enzyme-linked immunosorbent assay (ELISA). We demonstrated that a lower serum adiponectin level was associated with male gender, higher gamma-glutamyltransferase (gamma-GGT), higher albumin, higher TNF-alpha, and steatosis grade. The higher level of serum adiponectin in patients with genotype 2a was demonstrated when compared with that in the patients with genotype 1b. Furthermore, of great interest, results suggested that the significant differences regarding viral genotype seemed to occur only in male patients with CHC but not in female patients. In conclusion, serum adiponectin was associated with gender, genotype, liver steatosis, and TNF-alpha in a Chinese population with CHC.

Insulin resistance and metabolic syndrome in chronic liver diseases: old entities with new implications

Insulin resistance (IR) and metabolic syndrome have recently been implicated in the pathogenesis and progression of chronic liver diseases, especially chronic hepatitis C (CHC) and non-alcoholic fatty liver disease (NAFLD). In this review, we provide current information on their deleterious effect on the liver, with particular interest in those two entities. In NAFLD, IR causes both the accumulation of fat in hepatocytes and the progression to non-alcoholic steatohepatitis (NASH). Moreover, the presence of metabolic syndrome seems to be associated with severe fibrosis in NASH patients. In CHC, IR develops early in the course of the disease and precedes steatosis. It is also independently associated with histological severity and negatively affects treatment response, irrespective of genotype. Consequently, therapies targeting IR and metabolic syndrome could indirectly ameliorate the prognosis of both NAFLD and CHC. As specific therapies do not exist, patients with metabolic syndrome and CHC and NAFLD should be counseled to lose weight and ameliorate their glycemic control and lipid profile.

Hepatitis C, insulin resistance and diabetes: clinical and pathogenic data

Epidemiological data indicate a strong risk for development of insulin resistance (IR), and, ultimately, overt diabetes mellitus (DM) in patients with chronic hepatitis C virus (HCV) infection. Steatosis, or fatty liver, is closely linked with IR in persons without HCV, such as those with metabolic syndrome, primarily due to increased visceral fat leading to altered adipokine production and increased free fatty acid (FFA) release. Moreover, there is evidence that liver fat can have an impact on the development of hepatic IR independently of changes in adipose tissue. Multiple mechanisms can account for the development of IR in patients with chronic HCV. In particular, there is evidence for a triangular interaction between steatosis, inflammatory processes and IR. In patients infected by the genotype 1 virus, steatosis is strongly related to IR, leading to a metabolic steatosis, while, in genotype 3 patients, steatosis is related to viral load in the context of a viral steatosis. Chronic inflammatory processes in the liver may be mediated by persistently activated macrophages and other immune cells, with concomitant overproduction of pro-inflammatory cytokines such as tumour necrosis factor-alpha. Activation of inflammatory pathways, together with increased levels of FFAs, can disrupt hepatocyte intracellular pathways and inhibit insulin signalling, leading to IR. Molecular studies have also shown that the HCV core protein can directly inhibit the insulin signalling pathway and increase reactive oxygen species production, both of which can further exacerbate IR. The available data provide an understanding of chronic HCV whereby chronic inflammatory processes, steatosis and IR contribute to each other, leading to an increased risk of DM, and its associated poor outcomes, in persons with chronic HCV.

Hepatitis C virus infection enhances insulin resistance induced by visceral fat accumulation

BACKGROUND/AIMS

To clarify the impact of visceral obesity on hepatitis C virus (HCV)-infected patients, we examined the relationship between insulin resistance development and visceral fat accumulation.

METHODS

We analyzed 87 HCV-infected patients with mild fibrosis (stage 1 or 2) in comparison with 125 sex- and age-matched patients with non-alcoholic fatty liver disease (NAFLD). The degree of visceral fat area (VFA; cm(2)) at the umbilical level was measured by abdominal computed tomography and divided into two grades: no visceral obesity, VFA<100 and visceral obesity, VFA>/=100. Insulin resistance was evaluated by homeostasis model assessment of insulin resistance (HOMA-IR) and the quantitative insulin sensitivity check index (QUICKI). Pancreatic beta-cell function was evaluated by homeostasis model assessment of beta-cell function (HOMA-beta). Serum soluble tumour necrosis factor (TNF)-receptors 1 and 2 and adiponectin were measured.

RESULTS

Insulin resistance evaluated by HOMA-IR and QUICKI was correlated with visceral fat accumulation, and was higher in HCV patients than in NAFLD patients with visceral obesity. HOMA-beta was higher in HCV patients than in NAFLD patients for each VFA grade. Serum-soluble TNF-receptors 1 and 2 were higher in HCV patients than in NAFLD patients with visceral obesity.

CONCLUSIONS

Hepatitis C virus infection is a risk factor for development of insulin resistance, particularly in patients with visceral obesity.

Adiponectin inhibits steatotic CD95/Fas up-regulation by hepatocytes: therapeutic implications for hepatitis C

BACKGROUND/AIMS

Steatosis may trigger hepatocytes to up-regulate CD95/Fas thereby increasing susceptibility to apoptosis, inflammation and fibrosis. We investigated this concept and potential roles of adiponectin and its receptors (AdipoR1; AdipoR2) in chronically HCV-infected patients.

METHODS

In 98 HCV+ patients and 20 controls, sera were tested for HCV genotypes, FFAs, adiponectin and the M30 apoptosis indicator, and biopsies were evaluated for steatosis/inflammation/fibrosis, CD95/Fas (mRNA/protein), adiponectin (mRNA/protein), AdipoR1/-R2 (mRNA) and M30 (protein). We also questioned whether adiponectin protects HepG2 hepatoblastoma cells from FFA-triggered CD95/Fas up-regulation and apoptosis.

RESULTS

Patients [HCV clades 1 (78%), 2 (3%) and 3 (19%)] revealed increased FFA and adiponectin serum levels (p = .005). Hepatocyte CD95/Fas up-regulation correlated with steatosis, inflammation and fibrosis (p = .004). Advanced fibrosis correlated significantly (p = .05) with serum M30. Liver adiponectin correlated with steatosis (p = .016), CD95/Fas (p < .001) and inflammation/fibrosis. Hepatocyte AdipoR2 mRNA specifically correlated with serum adiponectin and steatosis (p = .003), while hepatocyte AdipoR1 mRNA dropped in pronounced fibrosis (p = .060). Finally, adiponectin protected HepG2 cells from FFA-triggered CD95/Fas expression and induction of apoptosis (p = .0396).

CONCLUSIONS

In chronic HCV infection, steatosis up-regulates hepatocyte CD95/Fas and thus increases apoptosis, which facilitates inflammation and fibrosis. The physiologic countermeasure of adiponectin up-regulation may offer clues for future therapeutic intervention.

Research progress of leptin and adiponectin in chronic liver diseases

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

Microsomal triglyceride transfer protein (MTP) -493G/T gene polymorphism contributes to fat liver accumulation in HCV genotype 3 infected patients

(A) A reduced activity of microsomal triglyceride transfer protein (MTP), a key enzyme of assembly/secretion of lipoproteins, is related to HCV steatosis. Host genetic background may influence development of steatosis. The aim of the study was to investigate the association between MTP-493 G/T gene polymorphism, fat liver accumulation and fibrosis progression in HCV infected patients. A total of 102 naïve patients with liver biopsy proven chronic hepatitis C were evaluated for MTP-493 G/T gene polymorphism, HCV RNA, HCV genotype, HOMA-IR, serum adiponectin, TNF-alpha and serum lipid levels. HCV genotype 3 infected patients carrying the T allele of the MTP gene polymorphism showed higher degree of steatosis than those carrying GG genotype (3.45 +/- 0.37 vs 1.30 +/- 0.45, respectively; P < 0.001). MTP'T' allele carriers also had higher HCV RNA serum levels (P < 0.01) and hepatic fibrosis (P < 0.001). Irrespective of MTP genotype, patients with HCV genotype 3 had lower levels of cholesterol, ApoB, HDL and LDL. In HCV genotype non-3 infected patients no parameters were associated with MTP gene polymorphism. In conclusion the presence of T allele of MTP-493G/T gene polymorphism predisposes patients infested with HCV genotype 3 to develop higher degree of fatty liver accumulation.

The role of adipokines in liver fibrosis

Liver fibrosis is a dynamic process consisting of the chronic activation of the wound healing reaction in response to reiterated liver damage, leading to the excessive deposition of fibrillar extracellular matrix into the liver and eventually, if the cause of injury is not removed, to liver cirrhosis. The term "adipokines" identifies a group of polypeptide molecules secreted primarily by adipose tissue, which exert local, peripheral and/or central actions. Additionally to their well-established role in controlling adipose tissue physiology, adipokines have been shown to be involved in different obesity-related diseases, such as hypertension, atherosclerosis and type 2 diabetes. Accumulating data demonstrate that obesity and insulin resistance are associated with a more severe and faster progression of the fibrogenic process in different chronic liver diseases. Therefore, numerous recent studies have analyzed the role played by adipokines in the hepatic wound healing process, identifying novel roles as modulators of liver pathophysiology. This review summarizes the more significant and recent findings concerning the role played by adipocyte-derived molecules, such as leptin, adiponectin and resistin, in the liver fibrogenic process. The actions of different adipokines on the biology of liver resident cells, as well as their effects in different animal models of liver injury are discussed. The variations in the circulating levels and in the intrahepatic expression of these molecules occurring in patients with different chronic liver diseases will be also analyzed.

[Insulin resistance in chronic hepatitits C]

OBJECTIVE

To revise the importance of insulin resistance in the development of chronic hepatitis C and its interference in the response to the antiviral treatment of these patients.

DATA SOURCE

Bibliographic revision of published papers in the MEDLINE and the authors data.

DATA SYNTHESIS

In the last years several published papers have demonstrated an important relationship between insulin resistance and chronic hepatitis C. Increased prevalence of type 2 diabetes mellitus, the development of hepatic steatosis (specially in non-3 genotype), a more rapid progression of hepatic disease and reduction in the sustained virological response to treatment with pegylated interferon plus ribavirin have been associated with insulin resistance in patients infected with HCV. The mechanism implied in the insulin resistance is the enhanced production of tumor necrosis factor by the HCV core. Tumor necrosis factor affects insulin receptor substrate phosphorylation, resulting in decreased glucose uptake and compensatory hyperinsulinemia. Increased liver iron accumulation and modification in the levels of adipocytokinemia can have an additional effect on insulin sensitivity in chronic C hepatitis.

CONCLUSIONS

Diagnosing and treating insulin resistance in patients with chronic hepatitis C could not only avoid complications but also prevent disease progression and increased the sustained virological rate to treatment with pegylated interferon plus ribavarin.

Increased risk of hepatocellular carcinoma among patients with hepatitis C cirrhosis and diabetes mellitus

Recent studies suggest that diabetes mellitus increases the risk of developing hepatocellular carcinoma (HCC). The aim of this study is to quantify the risk of HCC among patients with both diabetes mellitus and hepatitis C in a large cohort of patients with chronic hepatitis C and advanced fibrosis. We included 541 patients of whom 85 (16%) had diabetes mellitus. The median age at inclusion was 50 years. The prevalence of diabetes mellitus was 10.5% for patients with Ishak fibrosis score 4, 12.5% for Ishak score 5, and 19.1% for Ishak score 6. Multiple logistic regression analysis showed an increased risk of diabetes mellitus for patients with an elevated body mass index (BMI) (odds ratio [OR], 1.05; 95% confidence interval [CI], 1.00-1.11; P = 0.060) and a decreased risk of diabetes mellitus for patients with higher serum albumin levels (OR, 0.81; 95% CI, 0.63-1.04; P = 0.095). During a median follow-up of 4.0 years (interquartile range, 2.0-6.7), 11 patients (13%) with diabetes mellitus versus 27 patients (5.9%) without diabetes mellitus developed HCC, the 5-year occurrence of HCC being 11.4% (95% CI, 3.0-19.8) and 5.0% (95% CI, 2.2-7.8), respectively (P = 0.013). Multivariate Cox regression analysis of patients with Ishak 6 cirrhosis showed that diabetes mellitus was independently associated with the development of HCC (hazard ratio, 3.28; 95% CI, 1.35-7.97; P = 0.009).

CONCLUSION

For patients with chronic hepatitis C and advanced cirrhosis, diabetes mellitus increases the risk of developing HCC.

Hepatitis C virus infection: molecular pathways to metabolic syndrome

Chronic infection with hepatitis C virus (HCV) can induce insulin resistance (IR) in a genotype-dependent fashion, thus contributing to steatosis, progression of fibrosis and resistance to interferon therapy. The molecular mechanisms in genotype 1 patients that lead to metabolic syndrome are still ambiguous. Based on our current understanding, HCV proteins associate with mitochondria and endoplasmic reticulum and promote oxidative stress. The latter mediates signals involving the p38 mitogen-activated protein kinase and activates nuclear factor kappa B. This transcription factor plays a key role in the expression of cytokines, tumor necrosis factor alpha (TNF-alpha), interleukin 6, interleukin 8, tumor growth factor beta, and Fas ligand. TNF-alpha inhibits the function of insulin receptor substrates and decreases the expression of the glucose transporter and lipoprotein lipase in peripheral tissues, which is responsible for the promotion of insulin resistance. Furthermore, reduced adiponectin levels, loss of adiponectin receptors, and decreased anti-inflammatory peroxisome proliferator-activated receptor alpha in the liver of HCV patients may contribute to reduced fatty acid oxidation, inflammation, and eventually lipotoxicity. This chain of events may be initiated by HCV-associated IR and provides a direction for future research in the areas of therapeutic intervention.

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.

Review article: nonalcoholic fatty liver disease and hepatitis C virus--partners in crime

BACKGROUND

Both nonalcoholic fatty liver disease (NAFLD) and chronic hepatitis C (CHC) are frequent causes of chronic liver disease. In recent years, there have been significant revelations as regards the relationship between NAFLD and CHC.

AIM

To conduct a systematic, evidence-based review of the epidemiology, pathophysiology and potential treatments of coexistent NAFLD and CHC.

METHODS

The terms such as hepatitis C, fatty liver, NAFLD, nonalcoholic steatohepatitis and steatosis were searched on PubMed up to January 2008. References from selected articles and pertinent abstracts were also included.

RESULTS

Hepatic steatosis affects up to 80% of patients with CHC and is dependent on both viral and host factors. While insulin resistance (IR) is associated with hepatic steatosis and hepatitis C virus, genotype-specific pathogenic mechanisms have been identified and are currently the focus of intense investigation in the literature. Clinical implications of concurrent NAFLD, CHC and IR include increased disease progression, elevated risk of hepatocellular carcinoma, and decreased response to antiviral therapy.

CONCLUSIONS

NAFLD and IR are common in patients with CHC virus infection. IR is a driving force in the development of hepatic steatosis. Because of the clinical implications of hepatic steatosis and IR in the setting of CHC, further studies evaluating treatments, which may increase response to antiviral therapy, are needed.

Interplay between oxidative stress and hepatic steatosis in the progression of chronic hepatitis C

BACKGROUND/AIMS

The contribution of oxidative stress to the pathogenesis of chronic hepatitis C (CHC) is still poorly elucidated. This study investigated the relationship between oxidative stress, insulin resistance, steatosis and fibrosis in CHC.

METHODS

IgG against malondialdehyde-albumin adducts and HOMA-IR were measured as markers of oxidative stress and insulin resistance, respectively, in 107 consecutive CHC patients.

RESULTS

Oxidative stress was present in 61% of the patients, irrespective of age, gender, viral load, BMI, aminotransferase level, histology activity index (HAI) and HCV genotype. Insulin resistance and steatosis were evident in 80% and 70% of the patients, respectively. In the patients infected by HCV genotype non-3, but not in those with genotype 3 infection HOMA-IR (p<0.03), steatosis (p=0.02) and fibrosis (p<0.05) were higher in the subjects with oxidative stress than in those without. Multiple regression analysis revealed that, HOMA-IR (p<0.01), fibrosis (p<0.01) and oxidative stress (p<0.05) were independently associated with steatosis, whereas steatosis was independently associated with oxidative stress (p<0.03) and HOMA-IR (p<0.02). Steatosis (p<0.02) and HAI (p=0.007) were also independent predictors of fibrosis.

CONCLUSIONS

In patients infected by HCV genotype non-3, oxidative stress and insulin resistance contribute to steatosis, which in turn exacerbates both insulin resistance and oxidative stress and accelerates the progression of fibrosis.

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

OBJECTIVES

To compare serum adiponectin and tumor necrosis factor (TNF)-alpha among patients with viral liver diseases; to investigate associations of serum adiponectin and TNF-alpha with histological or viral characteristics of chronic hepatitis C (CHC); to investigate adiponectin and TNF-alpha alterations during interferon (IFN)-alpha treatment; and to assess the relationship between serum adiponectin and TNF-alpha and response rates to treatment.

METHODS

Adiponectin (mug/mL) and TNF-alpha (pg/mL) determinations by enzyme-linked immunosorbent assay (ELISA) in serial samples (before, the middle, the end, and 6 months after the end of treatment) from 83 CHC and 59 chronic hepatitis B (CHB) patients. Forty-three blood donors served as healthy controls. Patients were treated with IFN-alpha (4.5 MU/t.i.w.) for 12 months in CHB cases, and IFN-alpha (3 MU/t.i.w.) plus ribavirin for 6-12 months according to hepatitis C virus (HCV) genotype in CHC cases.

RESULTS

After adjustment for gender and body mass index (BMI), HCV genotype 3 overweight patients (BMI > 25 kg/m(2)) had significantly lower adiponectin (7.3 +/- 2.7) at baseline compared with non-3 HCV genotype overweight patients (P < 0.05). Lower adiponectin (HCV genotype 3, P= 0.02 and HCV genotype 1, P= 0.025) and higher TNF-alpha (P= 0.025) at baseline were identified as independent predictors of liver steatosis in CHC patients. Lower adiponectin was also identified as an independent predictor of no virological response at the end of treatment (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.66-0.87, P < 0.001). At the end of IFN-alpha therapy, only HCV genotype 3 patients had significantly higher serum adiponectin (10.4 +/- 6.3) compared with its levels before treatment (8.7 +/- 4.7, P < 0.05).

CONCLUSIONS

This study suggests that HCV genotype 3 may directly affect adiponectin. This is further supported by the significant increase in adiponectin at the end of treatment only in HCV genotype 3 patients. Serum adiponectin at baseline appears to be an independent predictor of liver steatosis and for the achievement of end-of-treatment virological response, while serum TNF-alpha at baseline was identified as an independent predictor only of liver steatosis.

Insulin resistance in chronic hepatitis C: association with genotypes 1 and 4, serum HCV RNA level, and liver fibrosis

BACKGROUND & AIMS

Our study was designed to test the association between insulin resistance (IR) and hepatitis C virus (HCV) genotypes, serum HCV RNA level and liver fibrosis stage in a large prospective cohort of chronic hepatitis C (CHC) patients.

METHODS

Six hundred consecutive patients (CHC, n = 500; chronic hepatitis B (CHB), n = 100) were evaluated on the day of liver biopsy. IR (Homeostasis Model for Assessment of Insulin Resistance) and all components of the metabolic syndrome were assessed. By logistic regression, independent factors associated with IR and those associated with significant fibrosis were assessed in nondiabetic and noncirrhotic CHC, respectively. Parameters of IR were compared between hepatitis B and 240 CHC matched by epidemiologic, metabolic, and histologic features.

RESULTS

IR was present in 32.4% of the 462 nondiabetic CHC and associated with the metabolic syndrome, genotypes 1 and 4, significant fibrosis, and severe steatosis. IR was diagnosed in 15% of 145 CHC without metabolic syndrome or significant fibrosis, and associated with genotypes 1 and 4, high serum HCV RNA level, and moderate-severe necroinflammation. Significant fibrosis was present in 51.1% of the 454 noncirrhotic CHC patients and associated with male sex, age >40 years, IR, moderate-severe necroinflammation, and severe steatosis. IR was less frequent in CHB than in matched CHC (5% vs 35%, respectively, P < .001).

CONCLUSIONS

IR is a specific feature of CHC, associated with genotypes 1 and 4 and high serum HCV RNA level. Significant fibrosis is associated with IR independent from steatosis.

Glucose abnormalities are an independent risk factor for nonresponse to antiviral treatment in chronic hepatitis C

OBJECTIVES

The influence of glucose abnormalities on the efficacy of antiviral treatment is unknown. This study investigated whether glucose abnormalities (impaired fasting glucose and type 2 diabetes) influence the response to antiviral therapy with interferon plus ribavirin in patients with chronic hepatitis C.

METHODS

A total of 178 treatment-naïve patients with chronic hepatitis C treated with combination therapy were retrospectively studied. SVR was assessed after completing treatment. Fasting plasmatic glucose was measured prior to therapy.

RESULTS

Compared with nonresponders (N = 111), patients with SVR (N = 67) had lower plasma glucose (94.1 +/- 12.7 vs 104.4 +/- 25.8 mg/dL, P= 0.001) and a lower prevalence of glucose abnormalities (24.24%vs 44.14%, P= 0.012). The SVR rate was 45.13% in patients with normoglycemia (N = 113), 28.26% in patients with impaired fasting glucose (N = 46), and 15.78% in type 2 diabetic patients (N = 19) (P < 0.001). Multivariate logistic regression identified genotype 1 (OR 1.55, 95% CI 1.01-2.41, P= 0.05), gamma-glutamyltranspeptidase level (OR 6.41, 95% CI 1.86-22.07, P= 0.003), and presence of glucose abnormalities (OR 2.33, 95% CI 1.04-5.20, P= 0.039) as being independently associated with the absence of an SVR. In addition, patients with glucose abnormalities (N = 65) showed a lower virological response rate when compared with a subgroup of normoglycemic patients (N = 65) matched for sex, age, and liver fibrosis (24.6%vs 44.6%, P= 0.001).

CONCLUSIONS

Glucose abnormalities are an independent predictor of poor virological response to combined therapy in hepatitis C virus infected patients.

Suppressor of cytokine signaling 3 (SOCS3) expression and hepatitis C virus-related chronic hepatitis: Insulin resistance and response to antiviral therapy

The response to antiviral therapy is lower in hepatitis C virus (HCV) patients with genotype 1 than in those with genotype 2. Overexpression of the suppressor of cytokine signaling 3 (SOCS3) gene in liver tissue is associated with a poorer treatment outcome in patients with chronic hepatitis C viral genotype 1. Also, insulin resistance has been implicated in nonresponse to an anti-HCV treatment. To understand why HCV genotype 1 patients respond differently, we investigated SOCS3 gene expression, metabolic syndrome (MS), and the response to therapy in a cohort of patients with HCV-related hepatitis. A total of 198 patients (108 with genotype 1 and 90 with genotype 2) treated with pegylated interferon plus ribavirin were consecutively enrolled in the study. We measured SOCS3 expression in Epstein-Barr virus-transformed lymphoblastoid cell lines derived from peripheral lymphocytes of a subset of 130 patients. MS was more frequent in genotype 1 patients than in genotype 2 patients (P < 0.01). Nonresponders (P < 0.01), MS (P < 0.001), and genotype 1 (P < 0.001) were significantly related to SOCS3 overexpression. However, SOCS3 levels were higher in nonresponders also, regardless of the genotype (P < 0.01). In a univariate analysis, the genotype (P < 0.001), age (P < 0.001), SOCS3 (P < 0.001), and MS (P < 0.001) were significantly related to the response to therapy. However, in a multivariate analysis, SOCS3 was the only independent predictor of the response (odds ratio = 6.7; P < 0.005).

CONCLUSION

We speculate that SOCS3 expression per se may influence the response to antiviral therapy and that the genotype 1b virus might induce its up-regulation. This may account for the different responses to therapy between genotype 1-infected and genotype 2-infected patients.

Controversies in and challenges to our understanding of hepatitis C

Discovered in 1989, the hepatitis C virus (HCV) continues to cause significant morbidity and mortality world-wide despite a huge research commitment to defining and understanding the virus and the disease it causes. This paper discusses a number of areas where progress in the management of the HCV have not kept pace with the scientific understanding of the HCV. It is suggested that in the fields of HCV prevention and providing access to treatment, practice falls short of what could be achieved. The role of alcohol in the pathogenesis of HCV liver injury is discussed. Discrimination against those with HCV infection and particularly those in prison settings fails to match good clinical practice. The complicated processes of sharing information between specialty groups is also discussed in an attempt to optimise knowledge dissemination in this field.