Interleukin-10 promoter polymorphisms in hepatitis C patients with and without Schistosoma mansoni co-infection

Co-infections of Schistosoma spp. and Malaria with Hepatitis Viruses from Endemic Countries: A Systematic Review and Meta-Analysis

BACKGROUND

Co-infection of schistosomiasis and malaria with hepatitis B virus (HBV) and hepatitis C virus (HCV) are common in countries where schistosomiasis and malaria are endemic.

OBJECTIVE

The present systematic review and meta-analysis was conducted to assess the prevalence of malaria/hepatitis viruses and Schistosoma/hepatitis viruses' co-infections.

MATERIALS AND METHODS

Relevant published studies on the co-infection of malaria and Schistosoma spp. with HBV and HCV were retrieved via international databases (PubMed, Scopus, Web of Science, and Google Scholar). Regarding meta-analysis, the random-effect model was employed by forest plot with a 95% of confidence interval (CI).

RESULTS

A total of 22 studies, including 15 studies with malaria/hepatitis viruses' co-infection and 7 studies with Schistosoma/hepatitis viruses' co-infection met the eligibility criteria. The co-infection of malaria/HCV and malaria/HBV in different populations were 15% (95% CI, 0-77%) and 5% (95% CI, 1-10%), respectively. Moreover, Schistosoma/HCV and Schistosoma/HBV co infection were detected in 7% (95% CI, 0-54%) and 2% (95% CI, 0-7%), respectively.

CONCLUSION

The overlaps between Schistosoma spp. and malaria with hepatitis B and C viruses in endemic countries with lower income levels were high, which deserve further attention.

Differential contribution of interleukin-10 promoter variants in malaria and schistosomiasis mono- and co-infections among Nigerian children

OBJECTIVE

Interleukin-10 (IL-10) is an anti-inflammatory cytokine produced by Th1 cells and macrophages. The rationale of this study was to examine and validate possible contributions of IL-10 promoter polymorphisms in sub-Saharan Africa in children infected with either Plasmodium falciparum or Schistosoma haematobium and in children co-infected with both parasites.

MATERIALS AND METHODS

A total of 309 Nigerian children aged 4-15 years were recruited. The study group consisted of individuals infected either with P. falciparum (n = 76) or S. haematobium (n = 94) in mono-infections, a group of children co-infected with both P. falciparum and S. haematobium (n = 62) and matched healthy controls (n = 77). The IL-10 promoter polymorphisms -1082G/A, -819C/T and -592C/A were genotyped by direct sequencing.

RESULTS

The frequencies of the IL-10 -1082GG genotype, the -1082G allele and haplotype GCC (positions -1082, -819 and -592) were higher in children infected with P. falciparum than in healthy controls, indicating that the -1082GG genotype and the -1082G allele and the GCC haplotype are associated with increased susceptibility to malaria infection (OR = 3.4, 95% CI = 1.2-10.8, P = 0.02; OR = 2.5, 95% CI = 1.1-3.4, P = 0.02; OR = 3.8, 95% CI = 2.0-7.2, P = 0.0001, respectively). Children with the -1082GG genotype had a higher parasitaemia than children with the -1082AA or -1082AG genotypes (P = 0.0017). Haplotype GCC occurred more frequently in children infected with S. haematobium, while haplotype GTA was less frequent than in controls (OR = 2.2, 95% CI = 1.2-4.4, P = 0.017 and OR = 0.1, 95% CI = 0.02-0.5, P = 0.0004, respectively). No differences in the frequencies of IL-10 promoter polymorphisms were observed between children with P. falciparum-S. haematobium co-infections and healthy controls.

CONCLUSION

Although IL-10 promoter polymorphisms are not associated with P. falciparum and S. haematobium co-infection, variant -1082G/A and haplotype GCC are associated with malaria, whereas the IL-10 haplotypes GCC and GTA are associated with schistosomiasis.

Interleukin-1 gene cluster Haplotype analysis in the chronic outcome prediction of the Hepatitis B virus infection

Hepatitis B virus (HBV) infection is well known as an important cause of the chronic liver disease. The screening of the genotype of certain cytokines might be helpful to predict the clinical outcome of an HBV infection. The present study investigates the relationship between the polymorphism and haplotypes of the Interleukin-1 (IL-1) gene family, including IL-1-alpha (IL-1A), IL-1-beta (IL-1B,) and IL-1 receptor antagonist (IL-1RN), with chronic HBV infection. A total of 297 chronic HBV and 333 matched on sex and age control individuals were genotyped using the standard sequence-specific-polymerase chain reaction primer (SSP-PCR) method. Four different haplotype analysis software packages were applied for data interpretation. The results showed excess genotype A1/A1 and A2/A2 at IL-1RN (40.2%, 39.9%), C/T at IL-1A-889 (55.6%), and C/C at IL-1B-511 (41.1%) in controls while A1/A1 at IL-1RN (59.3%), T/T at IL-1B-31 (46.5%), C/T at IL-1B + 3953 (65%), in chronic HBV infection cases. A total of 148 haplotypes were observed overall (96 in the case group and 89 in the control group). The haplotype combination of genotype A1/A1 at IL1-RN along with a C/T for all three IL-1B polymorphic positions and either C/T or T/T at the IL-1A-899 position may increase the probability of the chronic outcome for the HBV infection.

Influence of IL10 Gene polymorphisms on the sustained virologic response of patients with chronic hepatitis C to PEG-interferon/ribavirin therapy

There are accurate but inconclusive data on the association of interleukin (IL) 10 polymorphisms with sustained virological response (SVR) in chronic hepatitis C (CHC). This meta-analysis aimed to derive a more precise estimation of the effects of IL10 gene polymorphisms (-1082G/A, -819C/T, -592C/A) and their haplotypes on SVR in CHC patients receiving pegylated interferon alpha (PEG-IFN-a) plus ribavirin. Literature search was conducted up to Jan., 2016, in PubMed, EMBASE and ISI Web of Science electronic databases. Statistical analyses were performed by STATA11.0 software, with odds ratios (ORs) and their 95% confidence intervals (CIs). A total of 14 studies involving 1687 CHC cases met the inclusion criteria. Analyses were stratified either by ethnicity or genotype of hepatitis C virus (HCV). The results indicated that IL10-1082A/G was associated with a significantly decreased SVR rate based on the heterozygous model (OR: 0.662, 95% CI: 0.467-0.938) and dominant model (OR: 0.648, 95% CI: 0.440-0.955). Similar results were found in the Egyptian and HCV-4 genotype in all gene models except the recessive model. Moreover, we observed that IL10-819T allele carriers was associated with a significantly increased SVR in the Caucasian population (OR: 1.380, 95% CI: 1.018-1.871). However, we did not detect any significant association of the -592C/A polymorphism or haplotypes with SVR in the total or subgroup populations. In conclusion, IL10-1082GG genotype and -1082G allele were associated with decreased SVR rate in CHC patients, especially for the Egyptian and HCV-4 genotype. Moreover, IL10-819T allele was more likely to get SVR in the Caucasian population.

Gene polymorphisms of IL-10 and MxA in responders and non-responders to interferon therapy in HCV Egyptian patients genotype 4

Hepatitis C virus (HCV) is a major cause of chronic liver disease, with about 170 million people infected worldwide. The standard regimen for treatment of HCV consists of a combination of pegylated interferon with ribavirin. Failure of interferon-α treatment in patients with chronic HCV infection remains a challenging obstacle. Both viral and host environmental factors have been implicated in reducing responsiveness to IFN-α therapy. Host genetic diversity is also believed to contribute to the different clinical outcomes in HCV infection. The objective of the study was to investigate the association of both IL-10 (-819 and -592) and MxA (-88 and -123) single-nucleotide polymorphisms (SNPs) of the promoter regions, with response to interferon (IFN) therapy in Egyptian patients infected with HCV genotype 4. Polymorphisms of both genes in 85 HCV patients and 100 controls were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The frequency of SNP was compared between sustained responders (n = 52) and non-responders (n = 33), as determined by biochemical and virological response to IFN and ribavirin combined therapy. The frequency of the -819T/T and the -592A/A genotypes of IL-10 was significantly higher among responders compared to non-responders (51.92 vs 39.4 %, P = 0.03; 51.92 vs 42.42 %;P = 0.046 respectively). The G/G genotype at position -88 of the MxA gene was significantly lower in responders than in non-responders (25 vs 75.76 %, P = 0.046), whereas heterozygotes (G/T) were more likely responders (65.38 vs 18.18 %, P = 0). The -123C/A genotype was significantly associated with responders (48.08 vs 30.30 %, P = 0.014). Findings suggest that homozygosity for both -819T/T and -592A/A polymorphisms of IL-10 gene and that heterozygosity for both -88G/T and -123C/A polymorphisms of the MxA gene are important host factors that influence the response to IFN therapy in patients with chronic HCV infection.

Influence of cytokine and cytokine receptor gene polymorphisms on the degree of liver damage in patients with chronic hepatitis C

Hepatic fibrosis may be the result of repetitive injury to hepatocytes caused by HCV infection and the immune response to it. Cytokines regulate the inflammatory response to injury and modulate hepatic fibrogenesis. Single nucleotide polymorphisms (SNPs) located in cytokine genes may influence the cytokine expression and secretion that may contribute to hepatic fibrogenesis in HCV infection. The aim of this study was to determine the genotype of 22 SNPs found in the genes of 13 cytokines/cytokine receptors to assess the influence of polymorphic variants on the stage of liver damage in Brazilian patients chronically infected with HCV genotype 1 only. 141 unrelated patients were grouped according to their stage of fibrosis: absence of fibrosis or patients in the initial stages of fibrosis (F0-F2, n = 84), patients with advanced stages of fibrosis or cirrhosis (F3-F4, n = 57), without cirrhosis (F0-F3, n = 103), and with cirrhosis (F4, n = 38). The comparison of frequencies in each sub-sample was performed by 2 × 2 contingency tables using the chi-square or Fisher's exact test. Stepwise logistic regression was also used to assess independent associations between cirrhosis or fibrosis with polymorphic variants. The TNFA-308G:A genotype conferred increased risk of fibrosis and cirrhosis. The TNFA-238G:G genotype was associated with protection from cirrhosis. The IL10-819C:T genotype conferred protection from fibrosis and the IL1B-511C:T genotype conferred increased risk of cirrhosis. Some of these genotypes showed results on the borderline of statistical significance in the bivariate analysis. We conclude that gene variants of cytokines/receptors may influence liver damage in patients chronically infected by HCV genotype 1.

Coinfection of Schistosoma Species with Hepatitis B or Hepatitis C Viruses

Although a considerable number of studies have been undertaken to date, it is still controversial as to whether or not coinfection with schistosomiasis increases the susceptibility to or progression from Hepatitis B virus (HBV) or Hepatitis C virus (HCV) infection. This review is a closer examination of the key studies conducted on human populations on clinical factors that were published in English between 1975 and January 2015. Our review is mainly based on tables containing the salient information, which are arranged first by study population, country of study and publication date. We provide further explanation, clarification and discussion in the text. As such, it includes both studies that have been conducted on general populations who are largely asymptomatic for clinical disease (Table 3), as well as those focussing on special populations, which are usually comprised of clinical patients. These special populations have been presented as follows: subjects with chronic liver disease or related conditions such as cirrhosis, Table 4; subjects with primary liver cancer, Table 5; subjects with schistosomiasis, Table 6; subjects with acute or chronic hepatitis resulting from HBV, Table 7 and, subjects with HCV, Table 8. We have presented studies that compared two mono-infected groups with one that is coinfected separately in Table 9, as these offer us the best basis from which to evaluate if any synergistic effects accompany coinfection. A number of factors contributed to the results reported in our tables. These included, but are not limited to: subject selection (i.e. asymptomatic cases typically drawn from the general population vs subjects presenting to a hospital or clinic with clinical disease); study design, which directly impacts our ability to infer causality (i.e. case series, cross-sectional, case-control, cohort study); use and choice of control population (i.e. apparently healthy subjects vs other hospital patients vs none); sample size, which directly impacts statistical power and can result in a Type II error; geographic area, which may reflect differences in population genetics, public health history, environmental differences or any number of other important factors (i.e. Egypt, Brazil, China); method of testing for schistosomal infections (i.e. stool vs antibody test); method of testing to determine if advanced schistosomal disease was present (i.e. ultrasound, liver biopsy vs none); method of serological testing for HBV (i.e. use of HBsAg alone or with other markers or DNA testing); method of serological testing for HCV (i.e. use of anti-HCV alone or with RNA testing) and, year of the study, which reflects among other things, technological improvements between tests as well as possible changes in the frequency of exposure in the populations under study (i.e. use of parenteral antischistosomal therapy vs the oral antischistosomal medication). Despite all these differences, throughout this review we have observed general patterns that seem largely consistent with one another. Studies conducted on general, largely asymptomatic populations tend to support the view that having one of the diseases in question (i.e. schistosomiasis) does not necessarily predispose one to becoming coinfected with another (i.e. HBV or HCV). Rather, the probability of becoming coinfected seems most closely associated with modes of transmission for either HBV or HCV in schistosome-endemic areas, such as the past use of parenteral antischistosomal therapy or frequent blood transfusion. Once coinfected, however, the clinical course of illness for those with Schistosoma-HBV or Schistosoma-HCV infections are typically much more severe than for mono-infected subjects. The strongest evidence for this was found in the half-dozen or so prospective cohort studies that systematically monitored disease progression in their subjects. With respect to HBV infection, coinfection with Schistosoma prolonged the carriage state and more often resulted in chronic hepatitis with greater cirrhosis as well as higher mortality. Much of the same was also observed with respect to HCV, where coinfection with Schistosoma was associated with a reduced ability to spontaneously resolve the viral infection and more often resulted in rapid fibrosis as well as higher mortality. Furthermore, two of these studies which were fully comparative in nature, support the supposition that there is a synergistic association between Schistosoma-HCV for both liver fibrosis and mortality. Immunological studies, all conducted on HCV, also generally seem to support this. The results of our research argue for greater primary prevention for both HBV and HCV in Schistosoma-endemic populations. Although no vaccine currently exists for HCV as it does for HBV, additional steps can still be taken to reduce transmission in high-risk populations. Greater use of the HBV vaccine is particularly advisable. Finally, additional observational, longitudinal studies conducted on human populations that are fully comparative in nature could help answer some of the remaining questions on both Schistosoma-HBV as well as Schistosoma-HCV coinfections. Some of these include the role of active versus past schistosomal infections, the role of genetic variants, as well as the effect of coinfection on treatment. Future studies should make a particular effort to use a sufficient sample size to ensure adequate statistical power, which was not often properly considered in many of the studies we reviewed for this paper.

Schistosomiasis, hepatitis B and hepatitis C co-infection

BACKGROUND

Schistosomiasis is a significant health problem in more than 70 countries distributed between Africa, Asia and South America, with an infection rate of one in 30 individuals. Data on Schistosomiasis, Hepatitis B virus (HBV) and Hepatitis C virus (HCV) co-infection are scarce; however, there is a high prevalence in countries where schistosomiasis is endemic.

METHODS

A systematic search was performed on published data from 1980-2014. Published papers in the databases Google, Medline, PubMed, and MiPc library were searched using the keywords epidemiology, pathogenesis and outcomes of HBV, HCV and schistosomiasis and data were extracted from the relevant studies.

RESULTS

The prevalence of HBV/schistosomiasis co-infection in countries where schistosomiasis is endemic was high, ranging between 9.6 to approximately 64% in Egypt, and a maximum of 15.8% among hospitalized patients in Brazil. Concurrent infection between HBV and schistosomiasis is often associated with countries where schistosomiasis is endemic and may lead to chronic liver inflammation. Similarly, HCV infection rates in schistosomiasis populations range from 1% in Ethiopia reaching up to 50% in Egypt.

CONCLUSION

There is controversy regarding the effects of HBV and HCV on schistosomiasis and vice versa. Vaccination might be a solution to the era of schistosomiasis and co-infection with HBV and HCV.

Influence of IL10 gene polymorphisms on the severity of liver fibrosis and susceptibility to liver cirrhosis in HBV/HCV-infected patients

BACKGROUND

Previous studies about the association of the interleukin-10 (IL-10) polymorphisms with the progression of liver fibrosis or cirrhosis susceptibility in chronic hepatitis B/C (CHB/C) disease were inconsistent. The aim of this meta-analysis was to derive a more precise estimation of the association.

METHODS

We searched Medline, PubMed, EMBASE and Web of Science electronic databases using the following key words: liver fibrosis/cirrhosis, IL10, and polymorphism. Statistical analyses were performed by STATA11.0 software, with odds ratios (ORs) and their 95% confidence intervals (CIs).

RESULTS

12 independent studies in relation to IL10-1082A/G, -819C/T and -592C/A polymorphisms were included in our study, which consisted of 197 moderate/severe liver fibrosis cases and 426 mild fibrosis controls as well as 536 liver cirrhosis cases and 881 non-cirrhosis controls. The results indicated that a significantly decreased risk of moderate/severe fibrosis was associated with the GCC haplotype (IL10-1082G, -819C and -592C) in the overall CHB/C patients (OR: 0.547, 95% CI: 0.317-0.946, P=0.031). We did not detect any significant association between these polymorphisms and liver cirrhosis susceptibility in the total population or a subgroup of Asians. However, subgroup analyses by different aetiologies showed that the -819T heterozygotes (TC) were associated with a significantly increased risk of HCV-related liver cirrhosis in the Japanese population (OR: 1.254, 95% CI: 1.033-1.522, P=0.022).

CONCLUSIONS

The putative high IL-10 production haplotype GCC is more likely to be associated with less severe liver fibrosis in CHB/C patients. Additionally, the IL10-819T allele may be a susceptible factor for HCV-related liver cirrhosis in the Japanese population.

Interaction Between the Neglected Tropical Disease Human Schistosomiasis and HCV Infection in Egypt: a Puzzling Relationship

Egypt has the highest prevalence of chronic hepatitis C virus (HCV) infection and seropositivity worldwide, and it has been proposed that this enhanced susceptibility to HCV is related to coinfection with schistosomiasis. Although currently, there are no studies regarding the actual prevalence of both human schistosomiasis and schistosomiasis/HCV coinfection evidences strongly support that eliminating human schistosomiasis from Egypt is necessary to reduce both HCV prevalence and liver pathology. The present review highlights the significant impact of the neglected tropical disease human schistosomiasis on both susceptibility of Egyptians to HCV coinfection, severity of the resulting liver pathology, and poor response to antiviral therapy. The immune evasion mechanisms exerted by the HCV-NS3/4A protease domain, and the possible impact of immune evasion mechanisms exerted by proteases of larval, worm and egg stages of the parasite Schistosoma on human susceptibility to HCV infection are discussed. In addition, schistosome immune evasion mechanisms may include immunosuppression that in turn prevents clearance of HCV viremia and leads to relapsing HCV infection and severe liver pathology. I propose the generation of a replicon system from the most prevailing genotype (HCV-4a) in Egypt and establishing its replication on hepatoplastoma or immune cells in presence of bilharzial antigens. Finally, the use of a humanized small animal model that can acquire both HCV and S. mansoni infections will be important to further understand in real time the impact of coinfection on both the immune system and liver pathology.

Relationship between IL-10 gene -1082A/G and -592C/A polymorphisms and the risk of hepatitis C infection: a meta-analysis

Increasing evidence suggests that interleukin-10 (IL-10) gene promoter polymorphisms may be associated with chronic hepatitis C virus (HCV) infection and HCV clearance. To more precisely estimate the association between these variants and the risk of HCV infection, we performed a meta-analysis of 26 studies describing the IL-10-1082A/G, -819C/T, -592C/A genotypes, including 4039 chronic HCV infection cases and 2902 controls. When compared with a healthy population, the -1082GG allele had a 43% increased risk of chronic HCV infection in combined populations (GG vs GA + AA: odds ratio (OR) = 1.433, 95% confidence interval (CI) = 1.052-1.952, P = 0.023). In subgroup analysis by ethnicity, a significant increased risk was associated with the -1082GG genotype in the Caucasian population (GG vs AA: OR = 1.390, 95% CI: 1.108-1.744, P = 0.004; GG vs GA + AA: OR = 1.621, 95% CI: 1.267-2.075, P = 0.000). However, no significant association was found in Asian, African or Chinese populations. Moreover, a higher distribution of -592A was found in the spontaneously recovered population (AA vs CC: OR = 0.585, 95% CI = 0.387-0.884, P = 0.011; AA + AC vs CC: OR = 0.738, 95% CI = 0.551-0.988, P = 0.041; AA vs AC + CC: OR = 0.788, 95% CI = 0.664-0.935, P = 0.006) than that in the chronic HCV infection population. In conclusion, the IL-10-1082GG allele may increase the risk of chronic HCV infection in Caucasian population, and people carrying the IL-10-592A allele are more likely to clear HCV spontaneously.

Hepatitis C virus genotype 4 with normal transaminases: histological changes, schistosomiasis and response to treatment

Among individuals with chronic hepatitis C virus (HCV) infection, approximately 30% of patients show persistently normal alanine aminotransferase (PNALT). Individuals with PNALT have been historically excluded from antiviral treatment. However, some studies have reported sudden worsening of disease in patients with PNALT, suggesting the need to treat such individuals. To evaluate this further, we compared fibrosis severity and response to treatment in patients with PNALT to patients with abnormal ALT. In addition, we investigated whether liver histology and schistosomiasis affect response to treatment differently in those with PNALT and abnormal ALT. A retrospective cohort study of 176 HCV-Genotype 4 (HCV-G4) patients treated with pegylated interferon (PEG-IFN) and ribavirin. Of 176 cases studied, 53 (30.1%) had normal ALT. Prevalence of pretreatment severe fibrosis, sustained virological response (SVR) and relapse were not significantly different in patients with PNALT (26%, 66% and 5.7% respectively) compared to those with abnormal ALT (32.5%, 60.7%, and 6.6% respectively). Multivariable logistic regression revealed that pretreatment ALT, pretreatment viral load, inflammation and schistosomiasis were not significantly associated with SVR [OR (95% CI), 0.75 (0.34-1.65); 0.92 (0.61-1.37); 1.64 (0.64-4.18); 0.90 (0.44-1.84) respectively]. Severe fibrosis was the only significant predictor of SVR [OR (95% CI), 0.38 (0.14-0.99)]. PNALT does not reflect the degree of fibrotic changes or predict SVR. Furthermore, schistosomiasis is a predictor of neither fibrosis nor poor response in patients with PNALT. Severe fibrosis is a strong and independent predictor of response to treatment. Therefore, it is important to treat individuals with PNALT levels regardless of schistosomiasis.

Pulmonary vascular disease associated with parasitic infection--the role of schistosomiasis

Parasitic diseases have been known to cause pulmonary vascular lesions. Schistosomiasis is the most common parasitic disease associated with pulmonary arterial hypertension, although other trematodes have been implicated. Systematic evaluation of and interest in this problem have been rekindled because of the current availability of pulmonary arterial hypertension treatment.

Functional gene polymorphisms of interleukin-10 are associated with liver disease progression in Japanese patients with hepatitis C virus infection

OBJECTIVE

The inter-individual difference in response to liver injury appears to be important in the progression of liver fibrosis. Interleukin 10 (IL-10) is an anti-inflammatory cytokine, and several functional gene polymorphisms have been found. The aim of this study was to examine the possible association of IL-10 polymorphisms with the progression of liver fibrosis in hepatitis C virus (HCV)-related chronic liver disease patients.

METHODS

We examined the IL-10 -1087 A/G and -824 T/C gene polymorphisms in 184 Japanese patients with HCV-related chronic liver disease: 94 chronic hepatitis (CH) and 90 with liver cirrhosis (LC).

RESULTS

There were no significant differences in the genotype distributions or allele frequencies of IL-10 -824 T/C and -1087 A/G between the CH and LC groups. However, among the cirrhotic patients, the lower transcriptional allele, -824 T homozygotes had significantly lower serum albumin and platelet counts, and a higher Child-Pugh score than the -824 C carriers, and the lower transcriptional allele, -1087 A homozygotes had a higher ICG-R 15 compared with -1087 G carriers. Haplotype analysis of IL-10 -1087/-824 showed no significant difference between the CH and LC groups, but the combinations of AT and AC haplotypes (AT/AT, AT/AC and AC/AC) had a significantly higher ICG-R 15 than the GC carriers.

CONCLUSION

IL-10 lower transcriptional -824 T allele, -1087 A allele, and -1087/-824 haplotypes AT and AC are risk factors for the progression of liver fibrosis in HCV-related chronic liver disease.

Liver fibrosis: from animal models to mapping of human risk variants

Liver fibrosis is the sequel of chronic liver diseases and the main reason for increased mortality in affected patients. The extent of liver fibrosis displays great interindividual variation, even after controlling for exogenous factors. Thus, host genetic factors are considered to play an important role in the process of liver scarring. From a genetic perspective, liver fibrosis is a complex trait with many genes contributing to the expression of the phenotype. In genetically manipulated and inbred animals several risk loci for liver fibrosis have been identified. Some of these loci have been replicated in case-control studies of patients with hepatitis C infection. In humans, genetic risk loci were identified by single marker studies, haplotype studies or the combination of single markers. Recently, the first genome-wide association studies have also been performed in patients with liver diseases. Some of the identified gene variants have been functionally characterized in vitro, thereby opening the potential for novel therapeutic approaches and risk stratification.

Interleukin-10 gene polymorphisms in association with susceptibility to chronic hepatitis C virus infection: a meta-analysis study

A relationship between chronic hepatitis C virus (HCV) infection and interleukin-10 (IL-10) gene polymorphisms has been reported with controversial results in different studies. In an effort to solve this controversy, we quantitatively summarized ten studies on this relationship by means of meta-analysis. Our analysis included ten case-control studies with 992 cases of chronic HCV infection and 1,123 controls. Analyses were performed with STATA version 9.0. The results showed that the IL-10 -1082GG genotype significantly increased the risk for persistent HCV infection (AA vs. GG: OR = 0.680, 95% CI = 0.489-0.947, P = 0.022; AG vs. GG: OR = 0.608, 95% CI = 0.439-0.840, P = 0.003; GG vs. AG + AA: OR = 1.570, 95% CI = 1.160-2.123, P = 0.003), but no statistically significant differences were observed between cases and controls for IL-10 -819C/T and IL-10 -592C/A polymorphisms (P > 0.05). In conclusion, this meta-analysis suggested that the IL-10 -1082GG genotype was associated with increased susceptibility for chronic HCV infection.