Activation of tumor necrosis factor-alpha system in chronic hepatitis C virus infection

Kinetics of soluble tumour necrosis factor (TNF)-alpha receptors and cytokines in the early phase of treatment for chronic hepatitis C: comparison between interferon (IFN)-alpha alone, IFN-alpha plus amantadine or plus ribavirin

We have previously studied the effect of three different treatment regimens with interferon (IFN)-alpha alone or in combination with amantadine or ribavirin on viral kinetics in the first month of therapy. To understand the regulation of cytokine immune response during early inhibition of HCV replication, we analysed the longitudinal profile of proinflammatory markers (soluble TNFRs), of type 1 cytokines [IFN-gamma and interleukin (IL-12)], and of a type 2 cytokine (IL-10). Twenty-two chronic hepatitis C patients received daily therapy for 6 months. Sera were collected at baseline, at 6, 12, 24, 30 and 48 h and at the 3rd, 7th, 15th and 30th days of treatment. All cytokines and receptors were evaluated by enzyme linked immunosorbent assay (ELISA). At baseline, a correlation was found between the two soluble TNFRs (P < 0.0001) and between the soluble TNFRs and ALT levels (P < 0.003), as shown previously. Regardless of the type of treatment, lower levels of soluble TNFR-p75 were present from day 3 in patients who had significant virus decay at day 30 (P < 0.01). Baseline IL-10 levels correlated with TNFR-p75 (P < 0.01) and with treatment response (P < 0.05) and a significant IL-10 reduction from baseline was observed from day 3 among responders, irrespective of the type of treatments (P < 0.05). IL-12 and IFN-gamma levels did not differ according to treatment or outcome. These findings suggest a pivotal role for IL-10 in orchestrating the antiviral immune response. Its early decline can favour the shift from a Th2 to a Th1 immune response, which has been shown to be associated with a long-term virological response to treatment.

Expression of the CXCR3 ligand I-TAC by hepatocytes in chronic hepatitis C and its correlation with hepatic inflammation

The factors that regulate lymphocyte traffic in chronic hepatitis C (CHC) are not completely defined. Interferon (IFN)-inducible T cell alpha chemoattractant (I-TAC) is a relatively new member of the CXCR3 chemokine ligand family that selectively recruits activated T cells to sites of inflammation. To determine if I-TAC plays a role in CHC, we investigated I-TAC expression in hepatitis C virus (HCV)-infected liver biopsy material. I-TAC messenger RNA (mRNA) levels were significantly increased in HCV-infected liver compared with normal liver, which correlated with both portal and lobular inflammation. I-TAC expression was localized to hepatocytes throughout the liver lobule, with those in close proximity to active areas of inflammation expressing the highest concentration of I-TAC. In vitro, I-TAC mRNA and protein expression was inducible in Huh-7 cells following either IFN-alpha or -gamma stimulation and synergistically with tumor necrosis factor (TNF)-alpha. Furthermore, transfection of Huh-7 cells with either poly(I:C) or HCV RNA representing the HCV subgenomic replicon induced I-TAC mRNA expression. HCV replication was also found to modulate I-TAC expression, with stimulation of Huh-7 cells harboring either the HCV subgenomic or genomic replicon showing significantly increased synergistic effects compared with those previously seen in Huh-7 cells alone with IFN-gamma and TNF-alpha. In conclusion, these results suggest I-TAC, one of the most potent chemoattractants for activated T cells, is produced by hepatocytes in the HCV-infected liver and plays an important role in T cell recruitment and ultimately the pathogenesis of CHC.

An analysis of tumor necrosis factor α gene polymorphisms and haplotypes with natural clearance of hepatitis C virus infection

The cytokine tumor necrosis factor alpha (TNF-alpha) is important in generating an immune response against a hepatitis C virus (HCV) infection. The functions of TNF-alpha may be altered by single-nucleotide polymorphisms (SNPs) in its gene, TNF. We hypothesized that SNPs in TNF may be important in determining the outcome of an HCV infection. To test this hypothesis, we typed nine TNF SNPs in a cohort of individuals with well-defined HCV outcomes. Three of these SNPs were typed in a second cohort. Data were analyzed using logistic regression stratifying by ethnicity, since rates of HCV clearance differ in black subjects versus white subjects. The SNP -863A was associated with viral clearance in black subjects (odds ratios (OR) 0.52, 95% confidence interval (CI) 0.29-0.93). Furthermore, the common wild-type haplotype -863C/-308G was associated with viral persistence in black subjects (OR 1.91, 95% CI 1.24-2.95). These findings were independent of linkage with human leukocyte antigen (HLA) alleles. Further study of this polymorphism and haplotype is needed to understand these associations and the role of TNF-alpha in determining outcomes of HCV infection.

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.

Hepatitis C virus infection and diabetes: direct involvement of the virus in the development of insulin resistance

BACKGROUND & AIMS

Epidemiological studies have suggested a linkage between type 2 diabetes and chronic hepatitis C virus (HCV) infection. However, the presence of additional factors such as obesity, aging, or cirrhosis prevents the establishment of a definite relationship between these 2 conditions.

METHODS

A mouse model transgenic for the HCV core gene was used.

RESULTS

In the glucose tolerance test, plasma glucose levels were higher at all time points including in the fasting state in the core gene transgenic mice than in control mice, although the difference was not statistically significant. In contrast, the transgenic mice exhibited a marked insulin resistance as revealed by the insulin tolerance test, as well as significantly higher basal serum insulin levels. Feeding with a high-fat diet led to the development of overt diabetes in the transgenic mice but not in control mice. A high level of tumor necrosis factor-alpha, which has been also observed in human chronic hepatitis C patients, was considered to be one of the bases of insulin resistance in the transgenic mice, which acts by disturbing tyrosine phosphorylation of insulin receptor substrate-1. Moreover, administration of an anti-tumor necrosis factor-alpha antibody restored insulin sensitivity.

CONCLUSIONS

The ability of insulin to lower the plasma glucose level in the HCV transgenic mice was impaired, as observed in chronic hepatitis C patients. These results provide a direct experimental evidence for the contribution of HCV in the development of insulin resistance in human HCV infection, which finally leads to the development of type 2 diabetes.

Response to combination therapy with interferon alfa-2a and ribavirin in chronic hepatitis C according to a TNF-alpha promoter polymorphism

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) is involved in the pathogenesis of chronic active hepatitis C. Polymorphisms in the promoter region of the TNF-alpha gene can alter the TNF-alpha expression and modify the host immune response. The present study aimed at the correlation of the G308A TNF-alpha polymorphism with the response to antiviral combination therapy in chronic hepatitis C.

PATIENTS AND METHODS

62 patients with HCV and 119 healthy unrelated controls were genotyped for the G308A TNF-alpha promoter polymorphism. The patients received 3 x 3 million units of interferon alfa-2a and 1,000-1,200 mg ribavirin daily according to their body weight. A response was defined as absence of HCV-RNA and normalization of S-ALT after 6 months of combination therapy.

RESULTS

With respect to the allele and genotype frequency, a significant difference was not observed between controls and patients with chronic hepatitis C. Furthermore, such a difference was also not observed if responders and non-responders to antiviral therapy were compared.

CONCLUSIONS

The promoter polymorphism of the TNF-alpha gene investigated herein is equally distributed in healthy individuals and patients with hepatitis C and does not seem to predict the response to therapy with interferon alfa-2a and ribavirin.

The severity of liver fibrosis is associated with high leptin levels in chronic hepatitis C

Recent attention has focused on the liver profibrogenic role of leptin in animal models. The purpose of this study was to evaluate the role of leptin and TNF-alpha in the severity of liver fibrosis in patients with chronic hepatitis C (CHC). We used a radioimmunoassay to determine serum leptin concentrations in 77 consecutive patients with CHC and 22 healthy controls. Leptin was correlated with liver histological (METAVIR) and metabolic indices. Sixty five patients had none to moderate liver fibrosis (F0-F2) and twelve severe fibrosis (F3-F4). Steatosis was observed in all but 27 patients. Leptin was significantly increased in patients compared with controls and was significantly more elevated in females both in patients and controls. The age, age at infection, prothrombin index, body mass index (BMI), triglycerides, glycaemia, ferritin, leptin and TNF-alpha, were associated with severe fibrosis. Steatosis was significantly more pronounced in patients with severe than those without or moderate fibrosis (P = 0.04). Only leptin was significantly and independently associated with severe fibrosis (OR = 1.2, CI 95%: 1.1-1.4, P = 0.03). Leptin was significantly associated with BMI (r = 0.64, P < 0.001) and glycaemia (r = 0.43, P < 0.001). Significant correlations were found between steatosis and BMI (r = 0.30, P < 0.01) and glycaemia (r = 0.30, P < 0.01). In patients with CHC and higher BMI and glycaemia levels, the severity of liver fibrosis is associated with serum leptin. TNF-alpha is a putative candidate involved in the mechanism.

Mechanisms of increased insulin resistance in non-cirrhotic patients with chronic hepatitis C virus infection

BACKGROUND AND AIM

Evidence showing a higher prevalence of diabetes mellitus (DM) in patients with chronic hepatitis C virus (HCV) infection has been accumulating. However, the reason why chronic HCV infection promotes DM remains unknown. In the present study, the authors focused on non-cirrhotic and non-diabetic patients with chronic HCV infection and evaluated the factors responsible for increases in insulin resistance.

METHODS

Fifty-six patients diagnosed with HCV-related chronic liver disease were included. Biochemical information including body mass index (BMI), aspartate aminotransferase (AST), alanine aminotransferase, cholinesterase, triglyceride, total cholesterol, hemoglobin, platelet count, glycosylated hemoglobin, immunoreactive insulin (IRI), and serum levels of tumor necrosis factor (TNF)-alpha and HCV-RNA were determined using venous blood samples obtained from each patient after overnight fasting. Homeostasis model assessment of insulin resistance (HOMA-IR), a simple and convenient measure of insulin resistance, was also calculated. The relationship between the stage of liver fibrosis and HOMA-IR, and the clinical factors responsible for the increase in HOMA-IR in non-diabetic patients was investigated.

RESULTS

Homeostasis model assessment of insulin resistance and IRI levels increased parallel with the progression of fibrosis. Among the non-diabetic patients with mild to moderate liver fibrosis, BMI, serum levels of AST and TNF-alpha were related with HOMA-IR (BMI: r = 0.395, P = 0.041; AST: r = 0.465, P = 0.014; TNF-alpha: r = 0.396, P = 0.040). In contrast, HOMA-IR related to TNF-alpha (r = 0.526, P = 0.013) in non-diabetic patients with advanced liver fibrosis.

CONCLUSION

Collectively, hepatic fibrosis and inflammation appear to play key roles in the increase in insulin resistance in patients with chronic HCV infection.

Impaired IRS-1/PI3-kinase signaling in patients with HCV: a mechanism for increased prevalence of type 2 diabetes

Patients with hepatitis C virus (HCV) infection have a greater risk of developing type 2 diabetes mellitus. However, the mechanism of this association is unclear. In this study, we examined the potential defects in upstream insulin signaling pathways in liver specimens obtained from nonobese/nondiabetic subjects with HCV infection. Fasting liver biopsy specimens were obtained from 42 HCV-infected subjects and 10 non-HCV-infected subjects matched for age and body mass index. Liver tissues were exposed to insulin and examined for the contents and phosphorylation/activation status of the upstream insulin signaling molecules by immunoprecipitation and Western blot analysis. HCV infection resulted in a trend toward a 2-fold to 3-fold increase in insulin receptor (IR) and insulin receptor substrate (IRS)-1 contents when compared with non-HCV. In contrast, insulin-stimulated IRS-1 tyrosine phosphorylation was decreased by 2-fold in HCV-infected subjects compared with non-HCV-infected subjects (P <.05). The observed reductions in IRS-1 tyrosine phosphorylation were accompanied by a 3.4-fold decrease in IRS-1/p85 phosphatidylinositol 3-kinase (PI3-kinase) association and a 2.5-fold decrease in IRS-1-associated PI3-kinase enzymatic activity (P <.05 vs. non-HCV). This was accompanied by a marked reduction in insulin-stimulated Akt phosphorylation without any alterations in mitogen-activated protein kinase (MAPK) phosphorylation. Cellular contents of the hepatic p85 subunit of PI3-kinase were comparable between HCV-infected and non-HCV-infected subjects. In conclusion, we found that (1). HCV infection leads to a postreceptor defect in IRS-1 association with the IR and (2). insulin signaling defects in hepatic IRS-1 tyrosine phosphorylation and PI3-kinase association/activation may contribute to insulin resistance, which leads to the development of type 2 diabetes mellitus in patients with HCV infection.

Insulin resistance is associated with chronic hepatitis C virus infection and fibrosis progression [corrected]

BACKGROUND & AIMS

Chronic hepatitis C virus infection is associated with an increased prevalence of type 2 diabetes. We hypothesized that virus-induced insulin resistance may be a mechanism for fibrogenesis in chronic hepatitis C virus infection.

METHODS

In 260 hepatitis C virus-infected subjects, we examined the relationship between histological findings and anthropometric and biochemical data, including insulin resistance determined by the homeostasis model assessment (HOMA-IR). We also compared fasting serum insulin, C peptide, and HOMA-IR levels between the subset of 121 hepatitis C virus patients with stage 0 or 1 hepatic fibrosis and 137 healthy volunteers matched by sex, body mass index, and waist-hip ratio.

RESULTS

Hepatitis C virus-infected subjects with stage 0 or 1 hepatic fibrosis had higher levels of insulin, C peptide, and HOMA-IR (all P < or = 0.01) compared with matched healthy controls. In the 250 hepatitis C virus patients (fibrosis stage 0 to 4), viral genotype and portal, but not lobular, inflammation were univariate predictors of HOMA-IR. By multiple linear regression analysis, independent predictors of HOMA-IR included body mass index (P < 0.001), previous failed antiviral treatment (P < 0.001), portal inflammatory grade (P < 0.001), and genotype 3 status (P = 0.01). Genotype 3 had significantly lower HOMA-IR than other genotypes (which were comparable when adjusted for effects of the remaining independent predictors). HOMA-IR was an independent predictor for the degree of fibrosis (P < 0.001) and the rate of fibrosis progression (P = 0.03).

CONCLUSIONS

Hepatitis C virus may induce insulin resistance irrespective of the severity of liver disease, and this effect seems to be genotype specific. Further, our findings support the hypothesis that insulin resistance may contribute to fibrotic progression in chronic hepatitis C virus infection.

Polymorphisms in tumour necrosis factor-alpha, transforming growth factor-beta, interleukin-10, interleukin-6, interferon-gamma, and outcome of hepatitis C virus infection

Cytokines play a key role in the regulation of immune responses. In hepatitis C virus infection (HCV), the production of inappropriate cytokine levels appears to contribute to viral persistence and to affect response to therapy. Cytokine genes are polymorphic at specific sites, and certain mutations located within coding/regulatory regions have been shown to affect the overall expression and secretion of cytokines. The aim of this study was to investigate the frequency of genotypes associated with polymorphisms of TNF-alpha, TGF-beta, IL-10, IL-6, and IFN-gamma and to determine their association with the outcome of HCV infection. Genotyping was carried out by polymerase chain reaction sequence-specific primers on genomic DNA isolated from 158 individuals. Of these, 66 had spontaneously recovered from infection (persistently HCV RNA negative), while 92 had persistent infection (persistently HCV RNA positive). All patients were genotyped as high or low producers of TNF-alpha and IL-6 and high, intermediate, or low producers of TGF-beta, IL-10, and IFN-gamma based on single nucleotide substitutions. A significant proportion of patients with viral clearance were genotyped with a low IL-6 production profile, whereas those with persistent infection were genotyped with a high production profile (P = 0.02). No associations were observed between polymorphisms of TNF-alpha, IL-10, or IFN-gamma and viral clearance or persistent infection. Furthermore, there were no associations between cytokine genotypes and severity of disease. Inheritance of some genotypes associated with polymorphisms of cytokine genes, such as IL-6, may be host genetic factors associated with outcome of HCV in a well-defined ethnically homogeneous cohort.

IL-10 and TNF-alpha polymorphisms and the recovery from HCV infection

Hepatitis C virus (HCV) infection becomes chronic in about 85% of infected individuals, whereas only 15% of infected people clear spontaneously the virus. It is conceivable that the host immunogenetic background influences the course of infection in term of recovery. Thus, in this study we have evaluated the effect of functionally relevant polymorphisms at tumor necrosis factor-alpha (TNF-alpha, i.e., 2 biallelic polymorphisms at nt -863 and nt-308 of the promoter) and interleukin-10 (IL-10) loci (i.e., 1 biallelic polymorphism at nt -1082 of the promoter), on the clearance of HCV infection. To this purpose, we compared 18 Sicilian patients who had spontaneously recovered from previous HCV infection with 42 Sicilian patients with current HCV infection and 135 Sicilian healthy patients. The results demonstrate a decreased frequency of the -863CC TNF-alpha promoter genotype (involved in high production of this pro-inflammatory cytokine) and an increased frequency of the -1082GG IL-10 promoter genotype (involved in high production of this anti-inflammatory cytokine) in patients recovered from HCV infection. The evaluation of combined TNF-alpha and IL-10 genotypes revealed a significant increase of the "anti-inflammatory genotype" (low-TNF/high-IL-10 producers) in resolved HCV infection group compared with patients with persistent HCV infection. On the whole, our findings suggest that a genetically determined control of the HCV-induced inflammatory response may play a role in the resolution of HCV infection.

Steatosis in chronic hepatitis C: association with increased messenger RNA expression of collagen I, tumor necrosis factor-alpha and cytochrome P450 2E1

BACKGROUND

Increased levels of tumor necrosis factor (TNF)-alpha and oxidative stress have been implicated as factors contributing to hepatic injury in fatty liver diseases. As steatosis is associated with an accelerated progression of fibrosis in chronic hepatitis C (HCV), we hypothesized that the messenger (m)RNA expression of genes involved with the production of reactive oxygen species, inflammation and cellular injury would be increased in liver tissue from subjects with steatosis and chronic HCV.

METHODS

Real-time polymerase chain reaction was performed to determine relative mRNA expression levels of collagen I, TNF-alpha, cytochrome P450 2E1 (CYP 2E1), transforming growth factor-beta1 and CD14 in liver biopsies from 38 patients with chronic HCV. The mRNA expression levels were compared between subjects with and without steatosis, fibrosis, and inflammation.

RESULTS

Multivariate analysis demonstrated that collagen I mRNA expression was increased by 199% in steatosis (P = 0.02), 85% in moderate to severe fibrosis (P = 0.02) and 157% in inflammation (P = 0.03). Livers of patients with steatosis also had an increase in TNF-alpha mRNA expression by 50% (P = 0.03) and CYP 2E1 expression by 37% (P = 0.04) compared with non-steatotic livers. Tumor necrosis factor-alpha protein was localized to Kupffer cells, bile ducts and portal inflammatory cells by immunohistochemistry.

CONCLUSION

Increased expression of TNF-alpha may be involved in the pathogenesis of liver injury and progression of fibrosis in individuals who have steatosis in association with chronic HCV.

Pathogenic interactions between alcohol and hepatitis C

Alcohol is the most commonly abused substance in the United States, and alcohol abuse leads to alcoholic liver disease, a long recognized major public health concern. The high prevalence of chronic hepatitis C virus (HCV) infection, along with the clinical observation that HCV infection is common in alcoholic patients presenting with liver disease, has directed attention to the interaction between alcohol and HCV infection. Clinical studies have identified alcohol use as an independent risk factor for progression of fibrosis in chronic HCV infection. Experimental evidence suggests additive inhibitory effects between HCV and alcohol on antiviral immune responses. In addition, specific pathways have been identified by which HCV core protein and alcohol interact to activate hepatocytes. Nonspecific inflammatory cell recruitment and proinflammatory cytokine activation have also been implicated in both alcohol- and HCV-induced liver diseases. Further investigation of these and other pathways by which alcohol and HCV interact should unravel the mechanisms that accelerate the progression of liver disease.

Serum concentration of gammaGT is a surrogate marker of hepatic TNF-alpha mRNA expression in chronic hepatitis C

Serum gammaGT levels and hepatic expression of tumor necrosis factor-alpha (TNF-alpha) are host factors that can independently predict the outcome of interferon (IFN) treatment in patients with chronic hepatitis C virus (HCV) infection. To explore whether a correlation exists between these two factors, we measured pretreatment gammaGT levels in serum and TNF-alpha mRNA levels in liver biopsies of chronic HCV patients. Seventy-two HCV patients treated with 3-to-5 million units of IFN-alpha three times a week were enrolled in the study. Treatment lasted 24 weeks and was followed by a 48-week follow-up period. Efficacy was assessed by measuring HCV RNA and alanine aminotransferase by the end of follow-up. Twelve patients (16.6%) showed a sustained biochemical and virological response. Normal pretreatment gammaGT levels, low HCV RNA titer, and infection with genotype other than HCV-1 were shown to be independent predictors of sustained response. Hepatic levels of TNF-alpha mRNA, quantified by polymerase chain reaction, were significantly higher in nonresponders (3.44 arbitrary units) compared to sustained responders (1.84 arbitrary units; P = 0.009). Values </=3.12 arbitrary units independently predicted a sustained response to IFN (P = 0.014). Finally, TNF-alpha mRNA levels were significantly correlated with serum gammaGT levels (r = 0.79, P < 0.0001). These findings suggest that serum gammaGT levels may represent a surrogate marker of hepatic TNF-alpha expression, thus explaining the importance of serum gammaGT levels in predicting treatment outcome.

Interaction of alcohol and hepatitis viral proteins: implication in synergistic effect of alcohol drinking and viral hepatitis on liver injury

Alcohol drinking and viral hepatitis are both recognized as major causes of liver disease worldwide, and they frequently coexist and synergistically cause liver injury in patients with chronic liver disease. Several mechanisms have been implicated in exacerbation of liver injury in patients with alcohol drinking and viral hepatitis. These include impairment of host defense and liver regeneration by alcohol consumption. The findings obtained from my laboratory have demonstrated that alcohol potentiates cooperatively several signals activated by hepatitis B virus X protein (HBX) or hepatitis C virus core protein, and HBX sensitizes hepatocytes to tumor necrosis factor-alpha (TNF-alpha)- and ethanol-induced apoptosis by a caspase-3-dependent mechanism, which may also contribute to the synergistic effect of alcohol drinking and viral hepatitis on liver injury.

Impact of human herpesvirus-6 on the frequency and severity of recurrent hepatitis C virus hepatitis in liver transplant recipients

A role of tumor necrosis factor-alpha (TNF-alpha) In the immunopathogenesis of hepatitis C virus (HCV) infection has been proposed. The novel herpes virus, human herpes virus-6 (HHV-6), is amongst the most potent inducers of cytokines, including TNF-alpha. The impact of HHV-6 viremia on the progression of recurrent HCV hepatitis was assessed in 51 HCV-positive liver transplant recipients. The frequency of recurrent HCV hepatitis did not differ between patients with HCV viremia (47.6%, 10/21) as compared with those without HCV viremia (46.7%, 14/30, p = 0.9). However, the patients with HHV-6 viremia had a significantly higher fibrosis score upon HCV recurrence than those without HHV-6 viremia (mean 1.5 vs. 0.3, p = 0.01). An association between cytomegalovirus (CMV) viremia and HCV recurrence was not documented; 50% (15/30) of the patients with CMV viremia and 42.8% (9/21) of those without CMV viremia had recurrent HCV hepatitis (p > 0.5). Receipt of ganciclovir (administered upon the detection of CMV viremia) was associated with lower total Knodell score (mean 5.2 vs. 6.9, p = 0.05) and a trend towards lower fibrosis score (mean 0.44 vs. 1.00, p = 0.12) in patients with recurrent HCV hepatitis. Thus, HHV-6 viremia in HCV-positive liver transplant recipients identified a subgroup of patients at increased risk for early fibrosis upon HCV recurrence.

Polymorphisms in the interleukin-10, tumor necrosis factor-alpha, and transforming growth factor-beta1 genes in chronic hepatitis C patients treated with interferon and ribavirin

BACKGROUND/AIMS

In hepatitis C infection, the production of inappropriate cytokine levels appears to contribute to viral persistence and to affect the response to antiviral therapy. Additionally, polymorphisms in the cytokine genes may affect the production of the cytokines. In this study, we determined the frequency of the genotypes associated with polymorphisms of the interleukin-10 and tumor necrosis factor-alpha gene promoters, and transforming growth factor-beta 1 gene leader sequence, and investigated their association with clinical features and the response to interferon-alpha and ribavirin therapy in chronic hepatitis C infection.

METHODS

Genomic DNA from 80 patients and 37 racially matched healthy controls was studied by polymerase chain reaction and direct automated sequencing.

RESULTS

The interleukin-10 -1082 G/G genotype was identified more frequently in patients than in controls (P=0.048). The transforming-growth factor-beta 1 +29 (codon 10) C/C genotype was associated with resistance to the therapy (P=0.029). After adjusting for potential confounding variables, patients exhibiting the C/C genotype were less likely to respond to treatment than patients with the T/T or T/C genotypes.

CONCLUSIONS

These results suggest that inheritance of the interleukin-10 -1082 G/G and the transforming growth factor-beta 1 +29 C/C genotypes, which appear to affect the cytokine production, may be associated with susceptibility to chronic hepatitis C infection and resistance to combined antiviral therapy.

Serum tumour necrosis factor-alpha and transforming growth factor-beta levels in chronic hepatitis C patients are immunomodulated by therapy

Our aims were: (i) to characterize serum levels of tumour necrosis factor alpha (TNF-alpha) and transforming growth factor beta (TGF-beta) in non-cirrhotics with hepatitis C; (ii) to correlate levels of theses cytokines with degree of disease at baseline; (iii) to characterize the immunomodulatory effects of therapy with response and (iv) to compare profiles of cytokines in patients treated with pegylated-interferon alpha-2b monotherapy (PMT) vs its combination with ribavirin (PCT1-low dose ribavirin and PCT2-high dose ribavirin). We studied 56 patients that were part of two randomized, controlled, clinical trials. At baseline, high TNF-alpha levels paralleled the degree of inflammation as determined by histology. In PCT2, a significant reduction was seen in levels of TNF-alpha, TGF-beta and fibrosis scores when comparing baseline with follow-up. In sustained responders, regardless of therapy, the histological activity scores were lower at follow-up as compared to baseline. In conclusion, PCT2 is able to constantly reduce and sustain TNF-alpha levels, which is responsible for the sustained decline in liver inflammation as shown by the histological activity index and it is also able to reduce fibrosis as judged both by TGF-beta levels and fibrosis scores.

Minimal liver injury in chronic hepatitis C virus infection is associated with low levels of soluble TNF-alpha/Fas receptors and acquisition in childhood

BACKGROUND/AIMS

The rate of progression to cirrhosis of chronic hepatitis C might be related to an upregulation of TNF-alpha/Fas pathways.

METHODS

The serum levels of soluble TNF-alpha type II receptor (sTNFr-II) and soluble Fas antigen (sFas) were analyzed in patients with different histological outcomes of chronic parenterally acquired HCV infection of similar duration.

RESULTS

One hundred and forty-five HCV-infected patients had a known duration of infection. Twelve (8.3%) patients had minimal changes and were assigned to the case group. The control group was selected from the 24 (17%) patients with cirrhosis and the 54 (37%) with chronic active hepatitis (CAH). Two controls, one with CAH and one with cirrhosis, were paired with the cases following these criteria: duration of infection, transmission route and sex. The proportions of genotype 1b and HCV RNA serum levels were similar among the groups. The median serum levels of sTNFr-II and sFas were significantly lower in the case group than in the control groups. The cases were significantly younger when they became infected than the control groups. Indeed, most cases were infected within the first 10 years of life. sTNFr-II and age at infection were independently associated with the minimal injury case group. When sTNFr-II was excluded from the logistic regression model, sFas and age at infection were independently associated with the case group.

CONCLUSION

The rate of progression of parenterally acquired chronic hepatitis C to end-stage liver disease might be related to an upregulation of the TNF-alpha/Fas pathways and an age-dependent host response.

The immunopathogenesis of hepatitis C virus infection

The outcome of HCV infection is determined by the interaction between the virus and the host immune system. The persistence of infection in most HCV-infected individuals, despite the presence of HCV-directed antibodies, suggests that such antibodies fail to induce viral clearance. Patients with self-limited hepatitis C have evidence of a polyclonal, multispecific CD8+ T-cell response along with a coordinated CD4+ T-cell response that is associated with eradication of HCV infection. Cytokines are produced both locally within the liver and systemically and may play an important role in controlling viral replication and contributing to hepatocellular damage through amplification of a nonspecific immune response. In most patients, the humoral, cellular immune, and cytokine response seem insufficient to eradicate infection. In its attempt to clear the virus from the liver, the immune system contributes to the hepatocellular injury seem in most chronically infected patients. A better understanding of the host's immune response may provide further insight on the pathogenetic mechanisms involved in development of chronic hepatitis and aid the development of better therapeutic strategies.

Modulation of tumor necrosis factor receptors 1 and 2 in chronic hepatitis B and C: the differences and implications in pathogenesis

Tumor necrosis factor (TNF) plays a role in the pathogenesis of chronic hepatitis B (CHB) and chronic hepatitis C (CHC). The difference in the cytokine responses between hepatitis B virus (HBV) and hepatitis C virus (HCV) infections may have implications in the pathogenesis of these diseases. We performed a comparative study to examine the possible differences in the TNF-TNF receptor (TNFR) response between CHB and CHC. We studied the cytokine levels of 38 patients with CHB, 40 patients with CHC and 9 patients with dual hepatitis B and C, and compared them with the baseline levels of 12 healthy controls. The plasma levels of TNF-alpha, interferon-gamma, interleukin (IL)-2, IL-4, IL-10 and soluble TNFR-1 and 2 (sTNFR-1 and 2) were quantified by enzyme-linked immunosorbent assays. The expression of TNFR-1 and 2 in liver tissues was examined in 30 cases of CHB and 15 cases of CHC by semiquantitative reverse transcription polymerase chain reaction. The results showed that sTNFR-1 levels correlated with liver inflammation in all patients, whereas this correlation was not found with sTNFR-2 or other cytokines. Liver inflammation indicators were higher in HCV RNA+ than in HCV RNA- CHC. Most significantly, sTNFR-1 levels correlated with liver inflammation in CHB, but not in CHC. However, the expression of TNFR-1 and 2 in liver was similar between CHB and CHC. These findings suggest that the TNFR signal transduction pathway is modulated differently in HBV and HCV infection.

Cellular pathology of atherosclerosis: smooth muscle cells prime cocultured endothelial cells for enhanced leukocyte adhesion

During the development of an atherosclerotic plaque, mononuclear leukocytes infiltrate the artery wall through vascular endothelial cells (ECs). At the same time, arterial smooth muscle cells (SMCs) change from the physiological contractile phenotype to the secretory phenotype and migrate into the plaque. We investigated whether secretory SMCs released cytokines that stimulated ECs in a manner leading to increased leukocyte recruitment and thus might accelerate atheroma formation. SMCs and ECs were established in coculture on the opposite sides of a porous membrane, and the cocultured cells were incorporated into a flow-based assay for studying leukocyte adhesion. We found that coculture primed ECs so that their response to the inflammatory cytokine tumor necrosis factor-alpha was amplified. ECs cocultured with SMCs supported greatly increased adhesion of flowing leukocytes and were sensitized to respond to tumor necrosis factor-alpha at concentrations 10 000 times lower than ECs cultured alone. In addition, coculture altered the endothelial selectin adhesion molecules used for leukocyte capture. EC priming was attributable to the cytokine transforming growth factor-beta(1), which was proteolytically activated to a biologically active form by the serine protease plasmin. These results suggest a new role for secretory SMCs in the development of atheromatous plaque. We propose that paracrine interaction between ECs and SMCs has the potential to amplify leukocyte recruitment to sites of atheroma and exacerbate the inflammatory processes believed to be at the heart of disease progression.

Fas-mediated apoptosis of peripheral blood mononuclear cells in patients with hepatitis C

In the present study, we demonstrated that a close relationship exists between hepatitis C virus (HCV) infection of peripheral blood mononuclear cells (PBMCs) and cell-surface Fas expression in patients with hepatitis C, and showed the possibility of PBMCs apoptosis via a Fas-mediated system. The expression of Fas on PBMCs was found by flowcytometric analysis to be significantly increased in these patients. In addition, the treatment of patients' PBMCs with anti-Fas antibody induced cell death, with nuclear condensation and fragmentation and cellular DNA fragmentation. These data indicate that the patients' PBMCs expressed a large amount of functional Fas on the cell surface and were susceptible to stimulation against Fas, causing apoptotic cell death. We then quantified the serum-soluble Fas ligand (sFasL), which was known to bind to Fas and induce the apoptotic signals into the sensitized cells. The patients' serum sFasL levels were significantly higher than those of normal subjects and showed a good negative correlation with their PBMC number. To demonstrate the correlation between Fas expression and HCV infection, nested reverse transcriptase polymerase chain reaction (RT-PCR) was performed to detect HCV RNA. Interestingly, HCV RNA was preferentially detected from Fas-positive cells but not from Fas-negative cells, which had been isolated from PBMCs by magnetic beads. These results suggest that HCV infection of PBMCs might induce Fas expression and additional stimulation such as sFasL might induce apoptosis in these Fas-expressing cells. These mechanisms, in addition to hypersplenism, may explain the decrease in the number of PBMCs observed in patients with chronic hepatitis C.

Interleukin 10 treatment reduces fibrosis in patients with chronic hepatitis C: a pilot trial of interferon nonresponders

BACKGROUND & AIMS

Interleukin (IL)-10 is a cytokine that down-regulates the proinflammatory response and has a modulatory effect on hepatic fibrogenesis. The aim of this study was to determine the effect of IL-10 on hepatic injury in patients with chronic hepatitis C.

METHODS

Twenty-four patients with chronic hepatitis C who had not previously responded to interferon-based therapy were enrolled in a randomized, double-blinded 2-dose trial in which they received either 4 or 8 microgram/kg IL-10 subcutaneously daily for 90 days. Liver biopsies were performed before and at the end of therapy.

RESULTS

IL-10 was well tolerated with 22 patients completing the study. Serum ALT levels normalized in 19 of 22 patients by the end of therapy and were sustained in 5 of 22. Hepatic inflammation decreased in 19 of 22 patients, with 11 having a decrease by >/=2. Fibrosis decreased in 14 of 22 patients (mean change, 3.6-2.6; P = 0.001). There was no change in serum HCV RNA levels. IL-10 therapy was associated with changes in serological markers, suggesting a reduction of immune response and fibrogenesis.

CONCLUSIONS

IL-10 therapy is safe and well tolerated in patients with chronic hepatitis C. Although it has no apparent antiviral activity, IL-10 normalizes serum ALT levels, improves liver histology, and reduces liver fibrosis in a large proportion of patients receiving treatment. Therefore, IL-10 may have therapeutic potential in patients with chronic hepatitis C patients who do not respond to interferon-based therapy.

Tumor necrosis factor (TNF)-alpha and TNF receptors in viral pathogenesis

Tumor necrosis factor-alpha (TNF-alpha) and TNF receptors (TNFR) are members of the growing TNF ligand and receptor families that are involved in immune regulation. The present report will focus on the role of the prototypic ligand TNF and its two receptors, TNFR1 and TNFR2, in viral pathogenesis. Although TNF was reported years ago to modulate viral infections, recent findings on the molecular pathways involved in TNFR signaling have allowed a better understanding of the molecular interactions between cellular and viral factors within the infected cell. The interactions of viral proteins with intracellular components downstream of the TNFR have highlighted at the molecular level how viruses can manipulate the cellular machinery to escape the immune response and to favor the spread of the infection. We will review here the role of TNF and TNFR in immune response and the role of TNF and TNFR signaling in viral pathogenesis.

Chemokine and Chemokine Receptor Interactions Provide a Mechanism for Selective T Cell Recruitment to Specific Liver Compartments Within Hepatitis C-Infected Liver

The role played by chemokines in regulating the selective recruitment of lymphocytes to different tissue compartments in disease is poorly characterized. In hepatitis C infection, inflammation confined to portal areas is associated with a less aggressive course, whereas T cell infiltration of the liver parenchyma is associated with progressive liver injury and cirrhosis. We propose a mechanism to explain how lymphocytes are recruited to hepatic lobules during bursts of necroinflammatory activity in chronic hepatitis C infection. We report here that lymphocytes infiltrating hepatitis C-infected liver express high levels of the chemokine receptors CCR5 and CXCR3. However, whereas the CCR5 ligands macrophage inflammatory protein-1α and -1β were largely confined to vessels within portal tracts, the CXCR3 ligands IFN-inducible protein-10 and monokine-induced by IFN-γ were selectively up-regulated on sinusoidal endothelium. In vitro, human hepatic sinusoidal endothelial cells secreted IFN-inducible protein-10 and monokine-induced by IFN-γ in response to stimulation with IFN-γ in combination with either IL-1 or TNF-α. This suggests that intrahepatic Th1 cytokines drive the increased expression of IFN-inducible protein-10 and monokine-induced by IFN-γ and thereby promote the continuing recruitment of CXCR3-expressing T cells into the hepatic lobule in chronic hepatitis C infection.