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

Host and viral factors contributing to CD8+ T cell failure in hepatitis C virus infection

Virus-specific CD8+ T cells are thought to be the major anti-viral effector cells in hepatitis C virus (HCV) infection. Indeed, viral clearance is associated with vigorous CD8+ T cell responses targeting multiple epitopes. In the chronic phase of infection, HCV-specific CD8+ T cell responses are usually weak, narrowly focused and display often functional defects regarding cytotoxicity, cytokine production, and proliferative capacity. In the last few years, different mechanisms which might contribute to the failure of HCV-specific CD8+ T cells in chronic infection have been identified, including insufficient CD4+ help, deficient CD8+ T cell differentiation, viral escape mutations, suppression by viral factors, inhibitory cytokines, inhibitory ligands, and regulatory T cells. In addition, host genetic factors such as the host’s human leukocyte antigen (HLA) background may play an important role in the efficiency of the HCV-specific CD8+ T cell response and thus outcome of infection. The growing understanding of the mechanisms contributing to T cell failure and persistence of HCV infection will contribute to the development of successful immunotherapeutical and -prophylactical strategies.

Immunomodulators, sFas and Fas-L as potential noninvasive predictors of IFN treatment in patients with HCV genotype-4

Recent studies have indicated that cytokines can be used as markers for disease progression in hepatitis C virus (HCV)-infected patients, therefore this study was conducted to determine the influence of pegylated IFN vs standard IFN on interleukin-2 receptor (IL-2R), IL-6R, IL-8, TNFR-I, TNFR-II, sFas, and sFas-L in Egyptian patients with chronic hepatitis C genotype 4, as no previous studies have been performed on this genotype. We also aim at establishing a possible relationship between these cytokines and the response to INF to determine whether they can be used as noninvasive markers for the response to INF therapy and as monitors for the outcome of treatment. Thirty-eight patients with chronic HCV hepatitis were investigated for the serum levels of the previously mentioned cytokines in a randomized opened controlled trial (22 patients treated with pegylated IFN and 16 patients treated with standard IFN). Cytokine levels were measured by ELISA at 0, 1 and 12 months of IFN therapy. There was marked increase in the serum levels of IL-2R and IL-6R in nonresponders to pegylated interferon, IL-8, TNFR-I and II were significantly higher in nonresponders to standard interferon but were also high in responders of pegylated interferon. sFas and sFas-L showed high levels among responders to pegylated interferon but the standard interferon was again less effective in this regard. Serum levels of TNFR-II, sFas and sFas-L have the potential to be used as serological markers for response to pegylated IFN therapy, and IL-8 is a predictor for nonresponse. Moreover, TNFR-I and II have the potential to be used as markers of response to standard IFN treatment. The persistent correlation between sFas and TNFR-II may elaborate the possible role of pegylated IFN in the induction of apoptosis as a possible new mechanism of viral clearance during treatment with pegylated interferon treatment.

Genetic polymorphisms of inflammatory cytokines and liver fibrosis progression due to recurrent hepatitis C

To ascertain whether single nucleotide polymorphisms (SNPs) regulating the expression of interferon-gamma (IFN-gamma), IFN-gamma receptor-1 (IFNGR-1), interleukin-6 (IL-6), IL-10, IL-18, and tumor necrosis factor-alpha (TNF-alpha) may be associated with early fibrosis progression of recurrent hepatitis C, 50 liver transplantation recipients (32 men, 18 women, median age 56 years) with a median histologic follow-up time of 54 months were studied; 98 healthy blood donors served as controls. Cytokine SNPs were determined by means of previously described PCR-based methods. On the basis of the SNP studies, a low, intermediate, or high producer cytokine phenotype was attributed to each patient. Only 1 of the 17 low IL-10 producers reached an Ishak staging score > 2, in contrast to 20 of the 33 patients who were intermediate or high IL-10 producers (Mantel-Cox, p < 0.005). Recipients who were low IL-10 producers and high IFN-gamma producers had significantly slower fibrosis progression in comparison to intermediate/high IL-10 producers and low IFN-gamma producers (p < 0.005). In conclusion, cytokine SNPs resulting in high and low producer phenotypes of both Th1 and Th2 cytokines appear to modulate the course of recurrent hepatitis C. Low IL-10 producers are those with the slowest histologic fibrosis progression.

Indirect regulation of CD4 T-cell responses by tumor necrosis factor receptors in an acute viral infection

Despite the well-recognized importance of CD4 T-cell help in the induction of antibody production and cytotoxic-T-lymphocyte responses, the regulation of CD4 T-cell responses is not well understood. Using mice deficient for TNF receptor I (TNFR I) and/or TNFR II, we show that TNFR I and TNFR II play redundant roles in down regulating the expansion of CD4 T cells during an acute infection of mice with lymphocytic choriomeningitis virus (LCMV). Adoptive transfer experiments using T-cell-receptor transgenic CD4 T cells and studies with mixed bone marrow chimeras indicated that indirect effects and not direct effects on T cells mediated the suppressive function of TNF on CD4 T-cell expansion during the primary response. Further studies to characterize the indirect effects of TNF suggested a role for TNFRs in LCMV-induced deletion of CD11c(hi) dendritic cells in the spleen, which might be a mechanism to limit the duration of antigenic stimulation and CD4 T-cell expansion. Consequent to enhanced primary expansion, there was a substantial increase in the number of LCMV-specific memory CD4 T cells in the spleens of mice deficient for both TNFR I and TNFR II. In summary, our findings suggest that TNFRs down regulate CD4 T-cell responses during an acute LCMV infection by a non-T-cell autonomous mechanism.

Cytokines and chronic liver disease

From an immunological point of view, the healthy liver has been usually associated with the phenomenon of tolerance. A microenvironment of regulatory cytokines produced by liver Kuppfer cells and liver sinusoidal endothelial cells has contributed, together with resident dendritic cells, to generate a tolerogenic environment in this tissue. In this review we discussed the intrahepatic responses to different sorts of liver injury, such as hepatotrophic viruses, alcohol or putative self-antigens. In each case we analyzed the impact of different cytokines in the clinical outcome of the different pathological situations.

Hepatitis C and risk of lymphoma: results of the European multicenter case-control study EPILYMPH

BACKGROUND & AIMS

Increasing evidence points toward a role of hepatitis C virus (HCV) infection in the etiology of malignant lymphomas. However, previous epidemiologic studies were limited in size to establish an association between HCV infection and specific lymphoma subtypes. We performed a large, multicenter, case-control study to address this question.

METHODS

The study comprised 5 European countries and included newly diagnosed cases of any lymphoid malignancy recruited between 1998 and 2004. Controls were matched to cases by 5-year age group, sex, and study center. In-person interviews were conducted to collect data on demographic, medical, and family history as well as environmental exposures. Serum samples of 1807 cases and 1788 controls (excluding human immunodeficiency virus-positive and organ-transplantation subjects) were screened for HCV infection using an enzyme immunoassay. Positive as well as randomly selected negative samples were subjected to HCV RNA detection and HCV genotyping.

RESULTS

HCV infection was detected in 53 (2.9%) lymphoma cases and in 41 (2.3%) control subjects (odds ratio [OR], 1.42; 95% confidence interval [CI]: 0.93-2.15). Restricted to individuals who tested positive for HCV-RNA (indicating persistent infection and active viral replication), the OR was 1.82 (95% CI: 1.13-2.91). In subtype-specific analyses, HCV prevalence was associated with diffuse large B-cell lymphoma (OR, 2.19; 95% CI: 1.23-3.91) but not with chronic lymphocytic leukemia or follicular, Hodgkin's, or T-cell lymphoma. The sample size was not sufficient to derive any conclusions for rare lymphoma entities such as splenic marginal zone lymphoma.

CONCLUSIONS

These results support a model that chronic HCV replication contributes to lymphomagenesis and establish a specific role of HCV infection in the pathogenesis of diffuse large B-cell lymphoma.

Gender susceptibility to chronic hepatitis C virus infection associated with interleukin 10 promoter polymorphism

Elevated levels of interleukin 10 (IL-10) were previously described for chronically hepatitis C virus (HCV)-infected patients. We determined by a sequence-specific oligonucleotide probing technique the IL-10 promoter genotypes in 286 Argentinean HCV patients grouped according to disease outcome. The GG genotype (position -1082) is known to be associated with high IL-10 production, GA is considered an intermediate producer, and AA is associated with low IL-10 production. We found an increase in frequency of the GG genotype in female patients who do not eliminate the virus (RNA(+)). In these patients, the GG frequency was 0.19, versus 0.10 in controls (P = 0.03). This association became more significant in those RNA(+) female patients with elevated hepatic transaminases (GG frequency of 0.25; P = 0.0013). Additionally, this genotype frequency was higher in noncirrhotic female patients than in controls (GG frequency for noncirrhotic female patients was 0.31; P = 0.009). In RNA(-) patients, the GA frequency was elevated compared with that in controls (GA frequency of 0.76 in RNA(-) patients versus 0.48 in controls; P = 0.01), that in all HCV patients (GA frequency of 0.43; P = 0.001), and that in RNA(+) patients (GA frequency of 0.40; P = 0.0005). We conclude that a gender effect is observed with women carrying the GG high IL-10 producer genotype. The higher levels of IL-10 present in those individuals are associated with a higher risk of an inefficient clearance of the HCV and the development of a chronic HCV infection together with a lower risk of progression to cirrhosis in female patients.

The two faces of interleukin 10 in human infectious diseases

Resolution of infections depends on the host's ability to mount a protective immune response. However, an exacerbated response to infections may result in deleterious lesions. Consequently, immunoregulatory mechanisms are needed to control immune response and prevent infection-associated lesions. Interleukin 10 may be a major regulator of innate and adaptive immunity in vitro and in animals, but its role in human infections is still unclear. Review of the published work reveals wide involvement of interleukin 10 in two major features of infectious diseases. On one hand, interleukin 10 prevents the development of immunopathological lesions that result from exacerbated protective immune response to acute and chronic infections. On the other hand, it is critically involved in persistence of bacteria and viruses by interfering with innate and adaptive protective immunity. Moreover, infections induce the expansion of interleukin-10-producing regulatory cells that are involved in protection against allergic diseases.

Evaluation of cytokine polymorphisms (TNFalpha, IFNgamma and IL-10) in Down patients with coeliac disease

BACKGROUND

In Down syndrome there is an increased prevalence of coeliac disease, but the reasons for this association are yet unknown.

AIMS

To evaluate a possible correlation between TNFalpha, IFNgamma and IL-10 genotype polymorphisms with the susceptibility to coeliac disease in Down syndrome patients.

METHODS

Single nucleotide polymorphisms of TNFalpha (-308G-->A promoter region), IFNgamma (+874T-->A promoter region) and IL-10 (-1082G-->A promoter region) have been studied in 10 Down patients with coeliac disease, in 40 Down patients without coeliac disease and in 220 healthy controls. Clinical features were also studied in coeliac disease-Down syndrome patients.

RESULTS

The 10 coeliac disease-Down syndrome patients had a biopsy proven coeliac disease afterward a serological testing positive to antigliadin, antiendomysium and antitransglutaminase antibodies. Intestinal biopsy showed total atrophy in 6/10 and partial villous atrophy in 4/10 of them. All coeliac disease-Down syndrome patients had silent forms of coeliac disease and classical trisomy 21. No significant differences were observed for the IFNgamma and IL-10 polymorphisms in the studied groups. A significant trend for increase of TNFalpha -308A positive frequency was observed in coeliac disease-Down syndrome patients compared to healthy controls (p=0.043).

CONCLUSIONS

Single nucleotide polymorphisms of IFNgamma and IL-10 do not play a role in predisposing Down syndrome patients to coeliac disease, while the TNFalpha -308 allele could be an additional genetic risk factor for coeliac disease in trisomy 21.

TNFalpha genotype affects TNFalpha release, insulin sensitivity and the severity of liver disease in HCV chronic hepatitis

BACKGROUND/AIMS

TNFalpha induces insulin resistance and promoter polymorphisms of TNFalpha gene affect the release of this cytokine, implicated in the pathogenesis of HCV-related diabetes and fatty liver. The aim was to define whether in patients with HCV chronic hepatitis TNFalpha genotype influences TNFalpha activity, insulin resistance, and the severity of the disease.

METHODS

186 patients, 65% with steatosis, 17% with diabetes. TNFalpha and sTNFR2 were determined by ELISA, insulin resistance by HOMA-R index and TNFalpha -238, -308, and -863 polymorphisms by restriction analysis.

RESULTS

TNFalpha, sTNFR2, and insulin resistance were higher in patients than in 89 controls. TNFalpha pathway activity was correlated with LDL cholesterol, steatosis, and insulin resistance, which, in turn, was correlated with the severity of liver damage. Patients subdivided according to TNFalpha genotype significantly differed for TNFalpha release, insulin sensitivity and the prevalence of cirrhosis. The -308 and -238 TNFalpha polymorphisms, characterized by increased promoter activity, were associated with higher TNFalpha activity, insulin resistance and severity of the disease, whereas the -863 polymorphism, characterized by reduced promoter activity, with lower TNFalpha activity, and higher insulin sensitivity.

CONCLUSIONS

TNFalpha genotype modulates the activity of the TNFalpha pathway, influences insulin sensitivity and the severity of HCV chronic hepatitis.

Common variable immunodeficiency: the immune system in chaos

Common variable immunodeficiency (CVID) is a heterogeneous disorder that is associated with low serum-immunoglobulin concentrations, defective specific-antibody production and an increased susceptibility to bacterial infections of the respiratory and gastrointestinal tracts. In spite of the identification of genes that are associated with several known primary immunodeficiencies, the basic immunologic and molecular defects of the majority of patients with CVID have remained obscure. Most of the studies aimed at understanding the immunopathogenesis of CVID suggest that this condition is primarily a T-cell disorder, although renewed attention on the genetic linkage and haplotype analysis in families of patients with CVID and on the role of dendritic cells and B cells has revealed several interesting features. This new information should assist in understanding the pathogenesis of CVID and improving the therapeutic strategies.

Bi-allelic presence of the interleukin-10 receptor 1 G330R allele is associated with cirrhosis in chronic HCV-1 infection

Immune response to viral infection is an important determinant of liver injury in chronic hepatitis C (CHC). Experimental and clinical data suggest a protective role of interleukin-10 (IL-10) in hepatic fibrogenesis. The significance of two SNPs of the interleukin-10 receptor 1 (IL-10R1), S138G (SNP3) and G330R (SNP4) was investigated on (i) susceptibility to CHC, (ii) progression of hepatic fibrosis and (iii) response to interferon/ribavirin therapy. DNA and liver biopsies were obtained from 212 patients with HCV (hepatitis C virus)-genotype-1 infection. The allele frequencies were 0.17 for SNP3 and 0.33 for SNP4, both of which were indifferent from healthy controls (0.17 and 0.32, respectively). Stage 1 liver fibrosis was found in 22 cases (10.4%), stage 2 in 108 (50.9%), stage 3 in 27 (12.8%), and stage 4 (cirrhosis) in 55 (25.9%). An association was found between the SNP4 allele and the presence of cirrhosis (P=0.01). Homozygous SNP4 individual variants segregated within the cirrhosis group (P=0.03). We found neither an association with SNP3 nor with the necroinflammatory disease activity (as measured by ALT levels) nor with the response to antiviral therapy. Our work implies that IL-10R1 SNP4 is a recessively inherited risk factor for hepatic cirrhosis in HCV genotype-1 infection.

Biomedicines to reduce inflammation but not viral load in chronic HCV--what's the sense?

Although cytokines and cytotoxic T lymphocytes (CTL) are among the predominant mechanisms of host defense against viral pathogens, they can induce an inflammatory response that often leads to tissue injury. Hepatitis C virus (HCV) infection, a major cause of liver-related disease, results in the induction of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), and CTL activity, followed by liver injury. Although inflammation facilitates the wound healing process, chronic persistence over several decades results in scar accumulation, fibrosis and often cirrhosis. This review summarizes biological data implicating a cause-and-effect relationship between TNF-alpha levels and the progression of fibrosis in chronic HCV infections, in contrast to the role of TNF-alpha in hepatitis B virus infections. Furthermore, an overview of therapeutic approaches to halting the inflammatory cascade in individuals with chronic HCV, including the use of agents to reduce the level of TNF-alpha, is presented.

Is there a future for TNF promoter polymorphisms?

The in vitro study of TNF promoter polymorphism (SNP) function was stimulated by the numerous case-control (association) studies of the polymorphisms in relation to human disease and the appearance of several studies claiming to show a functional role for these SNPs provided a further impetus to researchers interested in the role of TNF in their disease of interest. In this review we consider case-control studies, concentrating on the autoimmune and inflammatory diseases rheumatoid arthritis, multiple sclerosis, ankylosing spondylitis, and asthma, and on infectious diseases including malaria, hepatitis B and C infection, leprosy and sepsis/septic shock. We also review the available evidence on the functional role of the various TNF promoter polymorphisms. In general, case-control studies have produced mixed results, with little consensus in most cases on whether any TNF polymorphisms are actually associated with disease, although results have been more consistent in the case of infectious diseases, particularly malaria. Functional studies have also produced mixed results but recent work suggests that the much studied -308G/A polymorphism is not functional, while the function of other TNF polymorphisms remains controversial. Studies of the TNF region are increasingly using extended haplotypes that can better capture the variation of the MHC region.

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.

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.

Interleukin-10 promoter polymorphisms and the outcome of hepatitis C virus infection

The natural outcome and response to treatment in hepatitis C virus (HCV) infection varies between individuals. Whereas some variation may be attributable to viral and environmental variables, it is probable that host genetic background also plays a significant role. Interleukin (IL)-10 has a key function in the regulation of cellular immune responses and in the suppression of pro-inflammatory cytokine secretion. Functional polymorphisms in the IL-10 gene have been described. We investigated the role of these polymorphisms in the outcome of HCV infection, treatment response and development of fibrosis in a case-control association study. Self-limiting infection was associated with the IL-10 (-592) AA genotype (OR=2.05; P=0.028). Persistent infection was associated with the IL-10 (-1082) GG genotype (OR=0.48; P=0.018). Sustained response to interferon therapy was associated with the IL-10 (-1082) GG genotype (OR=2.28; P=0.005) and the haplotype GCC (OR=2.27; P=0.020). The IL-10 (-1082) AA genotype and the ATA/ATA and ACC/ACC homozygous haplotypes were more frequent among patients with rapid fibrosis. Furthermore, the microsatellites IL-10.R and IL-10.G were associated with interferon response with IL-10R.2 conveying susceptibility (OR=1.80; P=0.034), and IL-10R.3 and IL-10.G13 being protective (OR=0.47; P=0.003 and OR=0.59; P=0.042, respectively). We conclude that polymorphisms in the IL-10 promoter appear to have some influence on the outcome of HCV infection, treatment and development of fibrosis.