Association of IL-18 promoter polymorphism with liver disease severity in HCV-infected patients

Inflammatory Consequences: Hepatitis C Virus-Induced Inflammasome Activation and Pyroptosis

Hepatitis C virus (HCV), despite the availability of effective direct-acting antivirals (DAAs) that clear the virus from >95% of individuals treated, continues to cause significant health care burden due to disease progression that can lead to fibrosis, cirrhosis, and/or hepatocellular carcinoma. The fact that some people who are treated with DAAs still go on to develop worsening liver disease warrants further study into the immunopathogenesis of HCV. Many viral infections, including HCV, have been associated with activation of the inflammasome/pyroptosis pathway. This inflammatory cell death pathway ultimately results in cell lysis and release of inflammatory cytokines, IL-18 and IL-1β. This review will report on studies that investigated HCV and inflammasome activation/pyroptosis. This includes clinical in vivo data showing elevated pyroptosis-associated cytokines in the blood of individuals living with HCV, studies of genetic associations of pyroptosis-related genes and development of liver disease, and in vitro studies aimed at understanding the mechanism of pyroptosis induced by HCV. Finally, we discuss major gaps in understanding and outstanding questions that remain in the field of HCV-induced pyroptosis.

Mechanisms of Hepatocellular Injury in Hepatitis A

Hepatitis A virus (HAV) infection is a common cause of acute viral hepatitis worldwide. Despite decades of research, the pathogenic mechanisms of hepatitis A remain incompletely understood. As the replication of HAV is noncytopathic in vitro, a widely accepted concept has been that virus-specific cytotoxic T cells are responsible for liver injury. However, accumulating evidence suggests that natural killer (NK) cells, NKT cells, and even non-HAV-specific CD8⁺ T cells contribute to liver damage during HAV infection. In addition, intrinsic death of virus-infected hepatocytes has been implicated as a cause of liver injury in a murine model of hepatitis A. Furthermore, genetic variations in host factors such as T cell immunoglobulin-1 (TIM1) and IL-18 binding protein (IL-18BP) have been linked to hepatitis A severity. This review summarizes the current knowledge of the mechanisms of hepatocellular injury in hepatitis A. Different mechanisms may be involved under different conditions and they are not necessarily mutually exclusive. A better understanding of these mechanisms would aid in diagnosis and treatment of diseases associated with HAV infection.

A significant association between CXCL10 -1447 A > G and IL18 -607 C > A gene polymorphism with human T-cell lymphotropic virus type 1 associated myelopathy/tropical spastic paraparesis (HAM-TSP), a case-control report from city of Mashhad, Iran

Human T-cell lymphotropic virus type 1 (HTLV-1) is the first isolated retrovirus from humans, and 2-3% of infected individuals suffer from HTLV-1 associated myelopathy tropical spastic paraparesis (HAM-TSP). Previous studies indicated that the risk of HAM-TSP could be correlated with the individuals' genetic alterations. Mashhad is one of the areas infected with HTLV-1 in Iran. This study designed to examine the association between several important gene polymorphisms and HAM-TSP. Genotypes of 232 samples from controls, HTLV-1 carriers, and HAM-TSP patients were examined for FAS-670 (A > G), CXCL10-1447 (A > G), Foxp3-3279 (C > A), IL-18 -137 (C > G), and IL-18 -607 (C > A) gene polymorphisms by different polymerase chain reaction (PCR) techniques. A non-significant association was observed between FAS-670 A > G, Foxp3-3279 C > A, and IL-18 -137 C > G gene polymorphisms and HAM-TSP. Nevertheless, a significant (P < 0.001) association between CXCL10-1447 A > G and IL-18 -607 C > A gene polymorphisms with HAM-TSP was observed in our study population. As previous studies revealed that the CXCL10 level in the cerebrospinal fluid of HAM-TSP patients was associated with the disease progression, and as we noticed, a direct association was observed between CXCL10-1447 A > G polymorphism and HAM-TSP. These polymorphisms might be recommended as a valuable prediction criterion for the severity of the disease. The contradiction between our findings and other studies regarding IL-18 -607 C > A gene polymorphism might be associated with various factors such as genotypes frequency in diverse races and population heterogeneity in the city of Mashhad.

Association of human platelet antigens polymorphisms with the levels of serum fibrosis marks in chronic hepatitis C patients

BACKGROUND

Host genetic polymorphisms influence the fibrosis progression of chronic hepatitis C (CHC) patients. Previous studies have shown the association of human platelet antigens (HPAs) polymorphisms with CHC. However, little is known regarding the association of HPAs polymorphisms with the fibrosis progression of CHC. The aim of this study was to determine the association of HPA -2, -3, -5 and -15 polymorphisms with the levels of serum fibrosis marks in CHC patients.

METHODS

The HPA -2, -3, -5 and -15 were genotyped by 5'-nuclease assay in 211 CHC patients, while the serum concentration of hyaluronic acid (HA), collagen IV (CIV), amino-terminal pro-peptide of type III procollagen (PIIINP), and laminin (LN) from the same samples were measured by time resolved fluorescence immunoassay.

RESULTS

The level of serum LN was significantly lower in CHC patients with HPA-15aa genotype compared to those with HPA-15ab/bb (P = 0.032) but did not differ among HPA-2, -3 and -5 genotypes. There were no difference in HA, CIV and PIIINP levels among HPA-2, -3,-5 and -15 genotypes.

CONCLUSIONS

This study demonstrates that HPA-15 aa polymorphism is associated lower serum LN in CHC, which suggests that HPA -15 aa may be involved in the fibrosis progression of CHC.

IL-18 in Blood Serum of Hepatitis C Patients Might be of Predictive Value for Individual Outcomes

OBJECTIVE

Pro- inflammatory cytokines including Interleukin (IL)-18 have been shown to be involved in the clearance of Hepatitis C virus (HCV) infection. However, changes in the balance of pro- and anti-inflammatory cytokines production during the immune response, can elicit a variety of liver damages. Therefore, it is of interest to study IL-18 serum levels in hepatitis patients and its correlation with HCV infection.

METHODS

Twenty-nine newly diagnosed HCV+ patients with no history of antiviral therapy, and 17 healthy controls, were enrolled in our study. Biochemical markers of liver disease were evaluated by biochemistry assay kits. Serum concentrations of IL-18 were determined with the ELISA method before and after treatment with pangenotypic direct-acting antivirals (DAAs) treatment.

RESULTS

Our results showed statistically significant difference in serum levels of IL-18 in HCV+ patients (692.261 ± 48.76) compared to healthy controls (520.00 ± 44.73) (P=0.021). However, there was no significant difference in IL-18 serum levels between the treated group compared to untreated patients (P=0.74). No significant correlations were detected between the level of IL-18 and liver enzyme levels.

CONCLUSION

According to our study, IL-18 might be a disease marker associated with HCV infection; however, this conclusion requires further investigation.

The decreased number and function of lymphocytes is associated with Penicillium marneffei infection in HIV-negative patients

BACKGROUND/PURPOSE

Penicillium marneffei (P. marneffei) infection, which has been traditionally considered as an indicator of immunosuppression, is one of the most common systemic opportunistic infections in patients with AIDS. Recently, more and more P. marneffei infections have been documented in HIV-negative patients without underlying diseases, which challenges the traditional view that P. marneffei infection is an indicator of immunosuppression. We aimed to evaluate the number and function of lymphocytes in HIV-negative patients with P. marneffei infection.

METHODS

15 HIV-negative P. marneffei-infected patients and 18 healthy controls were recruited and investigated. The number and function of lymphocytes were analyzed by flow cytometry.

RESULTS

Most laboratory tests were within the reference ranges, except for a significant increase in total IgE in P. marneffei-infected patients. Lymphocyte subset analysis showed that the number of CD4⁺ T cells and NK cells was significantly decreased in HIV-negative marneffei-infected patients compared with healthy controls. However, almost half of the marneffei-infected patients still had normal levels of lymphocytes. A further analysis of cell function showed that the activation and proliferation of CD4⁺ T cells, the cytotoxicity of CD8⁺ T cells and NK cells, and the cytokine secretion potential of CD4⁺ T cells and NK cells were all impaired, in comparison with healthy controls.

CONCLUSIONS

P. marneffei infection has to be regarded as an indicator of immunosuppression. A further investigation of cell function is required in patients with opportunistic infection, as the cell function may be impaired in this condition.

Impacts of Interleukin-18 Polymorphisms on the Incidence of Delayed-Onset Cytomegalovirus Infection in a Cohort of Kidney Transplant Recipients

Background

The incidence of cytomegalovirus (CMV) infection in solid organ transplant recipients may be reduced by antiviral prophylaxis, but this strategy may lead to delayed-onset CMV infection. The proinflammatory cytokine interleukin (IL)-18 plays a major role in viral host defense responses. This study examines the impacts of 2 single-nucleotide polymorphisms (SNPs) in the promoter region of the IL-18 gene, -607C/A (rs1946518) and -137G/C (rs187238), on the incidence of delayed-onset CMV infection in patients undergoing kidney transplant.

Methods

This retrospective study analyzed 2 IL-18 SNPs in consecutive adult kidney transplant recipients using real-time polymerase chain reaction with TaqMan probes. Participants were enrolled over the period 2005–2013 and stratified according to their IL-18 SNP genotype. The concordance index (Harrell’s c-index) was used as a measure of the discriminatory power of the predictive models constructed with bootstrapping to correct for optimistic bias.

Results

Seven hundred nine patients received transplants in the study period, and 498 met selection criteria. Cytomegalovirus infection and disease incidence were 38% and 7.5%, respectively. In multivariate competing risk regression models, carriers of the -607C/-137G haplotype who received prophylaxis showed a higher incidence of CMV replication after antiviral agent discontinuation (hazard ratio = 2.42 [95% confidence interval, 1.11–5.26]; P = .026), whereas CMV disease was not observed in those given prophylaxis who were noncarriers of this polymorphism (P = .009).

Conclusions

Our findings suggest that the -607C/-137G IL-18 haplotype is associated with a higher incidence of postprophylaxis CMV replication. The prior identification of this polymorphism could help select alternative measures to prevent delayed-onset CMV infection in these patients.

Inflammasome Genes' Polymorphisms in Egyptian Chronic Hepatitis C Patients: Influence on Vulnerability to Infection and Response to Treatment

Chronic inflammation is a pivotal contributor to the liver damage mediated by hepatitis C virus (HCV). The NOD-like receptor, pyrin domain-containing 3 (NLRP3) inflammasome is activated by HCV in both hepatocytes and Kupffer cells. The aim of our study was to investigate the association of nine single-nucleotide polymorphisms in four inflammasome genes (NLRP3, CARD8, IL-1β, and IL-18) with the susceptibility to HCV infection and outcome of interferon treatment in 201 Egyptian chronic hepatitis C patients and 95 healthy controls. The genotyping was conducted using TaqMan predesigned SNP assay. In the comparative analysis, the CC genotype of the NLRP3 rs1539019 was found to be associated with the lower risk to chronic HCV infection (OR: 0.33, 95% CI: 0.17-0.62). This association was also found for the CA genotype and the A allele of the NLRP3 rs35829419 (OR: 0.18 and 0.22, respectively), in addition to the GG genotype and G allele of IL-18 rs1946518 (OR: 0.55 and 0.61, respectively). In contrast, the AA genotype of the IL-1β rs1143629 was significantly more frequent in HCV patients (OR: 1.7, 95% CI: 1-2.86). Notably, the frequency of the AA genotype of NLRP3 rs1539019 was significantly higher in patients with lack of response (NR) to the interferon treatment (OR: 1.95, 95% CI: 1-3.7). A similar association was found for both the CC genotype and C allele of the NLRP3 rs35829419 (OR: 2.78 and 2.73, respectively) and for the TT genotype and T allele of CARD8 rs2043211 (OR: 2.64 and 1.54, respectively). Yet, the IL-1β (rs1143629, rs1143634) and IL-18 (rs187238, rs1946518) polymorphisms did not show any significant association with response to interferon treatment. In conclusion, this study reports, for the first time, the association of genetic variations in NLRP3 with hepatitis C susceptibility and response to treatment in Egyptian patients. However, further large-scale studies are recommended to confirm our findings.

Genetic polymorphisms -137 (rs187238) and -607 (rs1946518) in the interleukin-18 promoter may not be associated with development of hepatocellular carcinoma

This study meta-analyzed the literature on possible association of polymorphisms -137 (rs187238) and -607 (rs1946518) in the interleukin-18 (IL-18) promoter with risk of hepatocellular carcinoma (HCC). The analysis included 8 case-control studies on the -137 polymorphism (1,318 cases, 2,254 controls) and 7 case-control studies on the -607 polymorphism (1,262 cases, 1,696 controls). None of the five genetic models suggested a significant association between the -137 polymorphism and HCC risk: allelic model, OR 0.99, 95% CI 0.74-1.34, P = 0.97; recessive model, OR 0.98, 95% CI 0.65-1.46, P = 0.91; dominant model, OR 1.35, 95% CI 0.73-2.52, P = 0.34; homozygous model, OR 0.99, 95% CI 0.65-1.49, P = 0.95; heterozygous model, OR 0.99, 95% CI 0.66-1.48, P = 0.94. Similar results were obtained in subgroup analyses of Asian patients, Chinese patients, or patients with hepatitis B virus (HBV)-related HCC. Similar results were also obtained for the -607 polymorphism across the entire study population as well as in the three subgroups. The available evidence suggests no significant association of the -137 or -607 polymorphisms with risk of HCC in general or specifically of HBV-related HCC. These conclusions should be verified in large, well-designed studies.

Role of Some Predominant Host Immunomodulators' Single Nucleotide Polymorphisms in Severity of Hepatitis B Virus and Hepatitis C Virus Infection

Hepatitis B and C infections can be either acute or chronic. The chronic infection can culminate in liver cirrhosis and hepatocellular carcinoma. Influence of the host genetic makeup on conversion of acute to chronic infection, development of cirrhosis, and hepatocellular carcinoma is an interesting area of research. Variability in different immune system genes may account for such differences in the outcome of infection. This article discusses single nucleotide polymorphisms in different host immunomodulator genes that have been frequently reported to influence the outcome of infection and severity of disease. The genetic variability could be utilized for the prediction of disease outcome and treatment responses.

Interleukin-10.rs1800896 and Interleukin-18.rs1946518 gene polymorphisms could not predict the outcome of hepatitis C virus infection in Egyptian patients treated with pegylated interferon plus ribavirin

A single-nucleotide polymorphism (SNP) in the interleukin (IL)-28B gene was used as a major predictor of the response to treatment in patients with hepatitis C virus (HCV) infection. Data examining the role of IL-10 and IL-18 gene polymorphisms among HCV genotype 4 (G4)-infected Egyptians in response to pegylated interferon (PEG-IFN) plus ribavirin (RBV) therapy are limited. This study investigated the impact of SNP at IL-10.rs1800896 (at position -1082) and IL-18.rs1946518 genes (at position -607) on the response to PEG-IFN/RBV therapy in HCV-infected Egyptians. This study was carried out on 100 HCV patients treated with PEG-IFN plus RBV and 100 healthy controls. The HCV patients included 50 treatment non-responders (NR) and 50 subjects with sustained virologic response (SVR). Genomic DNA from venous blood of subjects was extracted and IL-10.rs1800896 and IL-18.rs1946518 genotypes were determined using allele-specific amplification and SYBR Green real-time PCR. Linkage disequilibrium between the two SNPs was estimated using Haploview software. The frequency of the IL-10.rs1800896 AA, AG and GG genotypes among non-responders were 16 %, 70 % and 14 % while among SVR subjects, the frequency was 34 %, 60 % and 6 %, respectively (p=0.073). On the other hand, the frequency of the IL-18.rs1946518 AA, AC and CC genotypes among non-responders was 14 %, 50 % and 36 %, respectively, while among responders, these frequencies were 28 %, 44 % and 28 %, (p = 0.220). Both markers were in linkage equilibrium (D' = 0.23; r (2) = 0.052). SNPs in the IL-10.rs1800896 and IL-18.rs1946518 genes could not predict the outcome of HCV infection in Egyptians treated with PEG-IFN/RBV.

ANALYSIS OF POLYMORPHISMS IN THE INTERLEUKIN 18 GENE PROMOTOR (-137 G/C AND -607 C/A) IN PATIENTS INFECTED WITH HEPATITIS C VIRUS FROM THE BRAZILIAN AMAZON

BACKGROUND

The hepatitis C virus has been recognized as the leading cause of chronic liver disease in the world. Host genetic factors have been implicated in the persistence of hepatitis C virus infection. Single nucleotide polymorphisms at positions -607 C/A (rs1946518) and -137 G/C (rs187238) in the IL-18 gene promoter have been suggested to be associated with delayed hepatitis C virus clearance and persistence of the disease.

OBJECTIVE

Identify these polymorphisms in a population infected with hepatitis C virus from the Brazilian Amazon region.

METHODS

In a cross-sectional analytical study conducted in Belém, Pará, Brazil, 304 patients infected with hepatitis C virus were divided into two groups: group A, patients with persistent infection; group B, patients with spontaneous clearance. The control group consisted of 376 volunteers not infected with hepatitis C virus. Samples were analyzed by RT-PCR for the detection of viral RNA and by RFLP-PCR to evaluate the presence of the -137 G/C and -607 C/A IL-18 gene promoter polymorphisms.

RESULTS

Comparison of polymorphism allele frequencies between the patient and control groups showed a higher frequency of allele C at position -607 among patients (P=0.02). When the association between the polymorphisms and viral infection was analyzed, patients carrying genotype C/A at position -607 were found to be at higher risk of persistent hepatitis C virus infection (P=0.03).

CONCLUSION

The present results suggest a possible role of the -607 IL-18 gene promoter polymorphism in the pathogenesis of hepatitis C virus infection.

IL-18 polymorphisms in hepatitis B virus related liver disease

Interleukine-18 (IL-18) was originally called interferon (INF-γ) inducing factor and plays a critical dual role in Th1 polarization and viral clearance. We aimed to explore whether single-nucleotide promoter polymorphisms (SNPs) are associated with the outcome of hepatitis B virus (HBV) infection. 271 HBV infected patients were recruited in this study out of these 109 were spontaneously recovered and 162 were diagnosed to be having persistent HBV infection which includes 48 chronic hepatitis, 84 liver cirrhosis, 30 HCC cases and were compared with 280 healthy controls. IL-18 promoter genotyping was performed with sequence-specific primers. The results demonstrated the significant involvement of genotype AA at position -607 in healthy controls (38.6%) when compared to cases (26.0%) (OR=0.54 (0.385-0.797)) and also associated with spontaneous clearance (37.6%) compared to persistent HBV infections (17.9%) (OR=2.76 (1.582-4.832)). Whereas, genotype CC at position -607 in cases (18.0%) when compared to healthy controls (6.7%) (OR=3.03 (1.734-5.303)) also associated with persistent HBV infections (24.1%) compared to spontaneous clearance (9.2%) (OR=0.31 (0.151-0.67)). And genotype GC at position -137 in cases (49.5%) compared to healthy controls (38.5%) (OR=1.55 (1.11-2.18)). Whereas, genotype GG at position -137 in healthy controls (56.8%) compared to cases (45.4%) (OR=0.63 (0.451-0.885)). No significant difference at position -137 was observed between spontaneous clearance and persistent HBV infections. These polymorphisms of the IL-18 gene promoter region at position -607 and -137 could be associated with different outcomes of HBV infection. The people with allele A at position -607 may be protected against HBV infection; moreover AA genotype is associated with spontaneous clearance.

Predictive potential of IL-18 -607 and osteopontin -442 polymorphism in interferon-based therapy of HCV infection in the Pakistani population

The adaptive immune system plays an important role in response to interferon plus ribavirin treatment of hepatitis C virus (HCV) infection. Cytokines play a significant role in the adaptive immune system. The production of cytokines may be regulated by single nucleotide polymorphisms (SNPs). This study was designed to examine the correlation of some important SNPs of cytokines with interferon plus ribavirin treatment of HCV infection in the Pakistani population. We followed 140 chronic HCV-infected patients in our study. All of these patients had completed their planned course of interferon plus ribavirin treatment. We also considered 120 healthy subjects as controls. The detection of interleukin-18 (IL-18) SNPs was performed by tetra-primers amplification-refectory mutation system polymerase chain reaction, while for genotyping of osteopontin (OPN), transforming growth factor beta (TGFβ), and N-acetylgalactosaminyltransferase 8 (GALNT8) SNPs, allele-specific polymerase chain reaction was performed. The distribution of the IL-18 -607AA genotype varied significantly between healthy control and patient groups. Its distribution was significantly high in healthy subjects than HCV patients (p = 0.031), signifying its potential involvement in the natural clearance of HCV infection. The occurrence of the -607AA genotype of IL-18 was also significantly higher in the sustained virological group (SVR) than in the nonresponder (NR) group (p = 0.046), highlighting its protective involvement in the treatment outcome of chronic HCV infection. The frequency of the OPN -442TT genotype was higher in the SVR group than in the NR group (p = 0.034), indicating a significant possible role of this genotype in therapy for HCV infection. No important association was found between TGFβ and GALNT8 genotypes and the natural clearance and treatment response of HCV infection. IL-18 -607AA and OPN -442TT genotypes can be used as positive predictive markers of interferon plus ribavirin treatment of HCV infection in the Pakistani population.

Impact of the IL-18 gene polymorphism in response to antiviral therapy in chronic HCV genotype 4 patients

INTRODUCTION

Interleukin (IL)-18 is a well-known major proinflammatory cytokine with broad biological effects. The major immunomodulatory functions of IL-18 include enhancing T cell and natural killer cell cytotoxicity. Serum levels of this cytokine were shown to increase in chronic hepatitis C patients compared to non-infected healthy people. An association between IL-18 gene promoter polymorphisms and pegylated interferon (PEG-IFN) and ribavirin treatment outcomes has been reported for individuals with chronic hepatitis C virus genotype 1 (HCV-1). In this study, HCV genotype 4 (HCV-4) patients were assessed for IL-18 gene polymorphisms and treatment outcomes or severity of liver disease because data concerning the impact of IL-18 gene polymorphisms on patients with HCV-4 infections are limited.

METHODS

This study included 123 chronic HCV-4 Egyptian patients and 123 apparently healthy volunteer blood donors who served as a control group. HCV genotyping was performed using the line probe assay. IL-18 genotyping was performed using the TaqMan Real-Time PCR method in all 246 patient and control samples.

RESULTS

In our study, all patients had HCV-4. IL-18 gene single nucleotide polymorphism (SNP) (-607C/A) genotype distributions and allele frequencies did not differ between HCV patients and normal healthy subjects or between patient groups when compared according to the therapeutic response. Moreover, the presence of an IL-18 SNP was not associated with histological disease severity. We conclude that the presence of the IL-18 SNP rs1946518 does not affect the outcome of chronic HCV-4 treatment in Egyptian patients.

CONCLUSIONS

The IL-18 SNP rs1946518 does not affect response to treatment in chronic HCV-4 patients.

Hepatitis C virus (HCV) interaction with astrocytes: nonproductive infection and induction of IL-18

Hepatitis C virus (HCV) infection causes the central nervous system (CNS) abnormalities in more than 50 % of chronically infected subjects. However, the underlying mechanisms are largely unknown. In this study, we characterized the HCV interactions with astrocytes, one of the putative HCV target cells in the brain. We demonstrated that primary human astrocytes (PHA) were very inefficiently infected by HCV, either in the cell-free form or through cell-cell contact. We then determined the potential restriction steps of HCV infection and replication in these cells. PHA expressed all known HCV receptors but failed to support HCV entry. HCV IRES-mediated RNA translation was functional in PHA and further enhanced by miR122 expression. Nevertheless, PHA did not support HCV replication regardless of miR122 expression. To our great surprise, we found that HCV exposure induced robust IL-18 expression in PHA and exhibited direct neurotoxicity. Taken together, these results showed that astrocytes did not support productive HCV infection and replication, but HCV interactions with astrocytes and neurons alone might be sufficient to cause CNS dysfunction.

Role of viral and host factors in interferon based therapy of hepatitis C virus infection

The current standard of care (SOC) for hepatitis C virus (HCV) infection is the combination of pegylated interferon (PEG-IFN), Ribavirin and protease inhibitor for HCV genotype 1. Nevertheless, this treatment is successful only in 70-80% of the patients. In addition, the treatment is not economical and is of immense physical burden for the subject. It has been established now, that virus-host interactions play a significant role in determining treatment outcomes. Therefore identifying biological markers that may predict the treatment response and hence treatment outcome would be useful. Both IFN and Ribavirin mainly act by modulating the immune system of the patient. Therefore, the treatment response is influenced by genetic variations of the human as well as the HCV genome. The goal of this review article is to summarize the impact of recent scientific advances in this area regarding the understanding of human and HCV genetic variations and their effect on treatment outcomes. Google scholar and PubMed have been used for literature research. Among the host factors, the most prominent associations are polymorphisms within the region of the interleukin 28B (IL28B) gene, but variations in other cytokine genes have also been linked with the treatment outcome. Among the viral factors, HCV genotypes are noteworthy. Moreover, for sustained virological responses (SVR), variations in core, p7, non-structural 2 (NS2), NS3 and NS5A genes are also important. However, all considered single nucleotide polymorphisms (SNPs) of IL28B and viral genotypes are the most important predictors for interferon based therapy of HCV infection.

Association of interleukin-18 gene polymorphisms with the outcomes of hepatitis C virus infection in high-risk Chinese Han population

Interleukin 18 (IL-18) gene polymorphisms have been reported to be associated with the outcomes of hepatitis C virus (HCV) infection in Americans, Indians and Europeans. We aimed to investigate whether the association can be replicated in Chinese Han population. Three IL-18 variants, -656G>T, -137G>C and +105A>C, were genotyped in three independent Han cohorts consisting of 552 cases and 784 controls. By using logistic regression analysis and multiple testing, haplotype GCC were associated with a protection from susceptibility to HCV. After stratified analysis, both the carriage of -137C allele in the older or hemodialysis subgroup and the carriage of +105C allele in the younger subgroup were found to be significantly associated with a decreased risk of HCV susceptibility. By using logistic regression analysis and multiple testing for the resolution of HCV infection, our study showed that +105C allele and haplotype GGC displayed a negative effect on HCV persistence. After stratified analysis, a significantly decreased risk for HCV persistence was found in +105C allele in the subgroups of young, male or female, drug user or hemodialysis and HCV-1 or HCV mixed genotype. No significant association was observed between -656G>T and the outcomes of HCV infection. Our results demonstrated that the carriage of -137C allele, +105C allele, haplotype -656G/-137C/+105C and haplotype -656G/-137G/+105C of IL-18 gene may contribute to better outcomes of HCV infection in high-risk Chinese Han population.

Association of interleukin-15 single nucleotide polymorphisms with resistance to brucellosis among Iranian patients

Interleukin (IL)-15, a Th1-related cytokine, triggers inflammatory cells' recruitment and increases the expression of interferon gamma (IFN-γ), which is an important cytokine in the immunity against brucellosis. Different single-nucleotide polymorphisms (SNPs) have been observed in the IL-15 gene, so this study aimed to investigate the probable association between these SNPs and susceptibility to brucellosis among Iranian patients. A total of 190 patients with brucellosis and 83 healthy milk farmers who consumed contaminated raw milk and dairy products from animals involved with brucellosis were included in this study. All the patients and the controls were genotyped for four IL-15 polymorphisms at positions 267, 367, 13687 and 14035 using polymerase chain reaction-restriction fragment length polymorphisms. The 267C and 13687A alleles, haplotypes CGCT and CAAA and the 267CC and 13687AA genotypes were significantly more frequent in the controls than in the patients (P = 0.014, 0.03, 0.006, 0.024, 0.026 and 0.01, respectively), so the variation in the IL-15 gene may be one of the factors affecting the resistance to brucellosis. In contrast, the frequency of haplotypes CGCA and TACT was significantly higher in patients compared with controls (P = 0.015 and 0.007, respectively), and interestingly the last one was observed only in the patients; therefore, it may serve as a predictive factor for brucellosis. In conclusion, it could be suggested that IL-15 genetic variants can affect resistance or susceptibility to human brucellosis among Iranian patients.

Interleukin-18 and interferon-gamma polymorphisms are implicated on proviral load and susceptibility to human T-lymphotropic virus type 1 infection

Interleukin-18 (IL-18) and interferon-gamma (IFN-γ) exert important functions in both innate and adaptive immune responses against intracellular pathogens and viruses. Previous studies suggested that host genetic factors, including cytokines gene polymorphisms, could be involved in the pathogenesis of human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Thus, we analyzed -137C/G and -607A/C of the IL-18 promoter and +874T/A of the IFN-γ in DNA samples from 98 HTLV-1-infected individuals exhibiting or not clinical symptoms and 150 healthy control individuals. The IL-18 promoter -607CC genotype was significantly lower in HTLV-1 asymptomatic carriers (HAC) and HTLV-1-infected individuals (HAC + HAM/TSP) than healthy control group. In contrast, the -607AC genotype was significantly higher in HAC and HTLV-1-infected individuals group compared to the healthy control group. The -137G/-607A IL-18 haplotype was higher in infected group than healthy control group, and the -137C/-607C IL-18 haplotype was increased in the healthy control group compared to the others. Finally, the IFN-γ polymorphism analysis showed that the HTLV-1-infected individuals with +874AT genotype presented higher proviral load than +874AA genotype. These data indicate that the IL-18-607AC genotype and -137G/-607A haplotype could be a risk factor for HTLV-1 infection, whereas the protective effect could be conferred by -607CC genotype and -137C/-607C haplotype. Also, the IFN-γ could be implicated on the proviral load levels.

Explanted liver inflammatory grade predicts fibrosis progression in hepatitis C recurrence

Factors present prior to liver transplantation (LT) that predict fibrosis progression in recurrent hepatitis C infection (HCV) after LT would be important to identify. This study sought to determine if histologic grade of HCV in the explant predicts fibrosis progression in recurrent HCV. The clinical and histologic data of all 159 patients undergoing their first LT for HCV at our center from 1998 to 2001 were retrospectively reviewed with follow-up through June 2008. Twenty-five cases were excluded for: non-HCV-related graft loss <90 days (19), recidivism (4), or unavailable explant or follow-up biopsies (2). A single pathologist scored (Ishak) explants in a blinded fashion. Patients were grouped by explant inflammatory grade ≤ 4 (group1) and >4 (group 2). Prospectively scored liver biopsies (protocol months 1 and 4, annually, and as indicated clinically) were reviewed for development of advanced fibrosis (bridging or cirrhosis). Cox proportional hazard regression was used to analyze the association of explant grade, donor, viral and LT factors with progression to advanced fibrosis. The groups were well-matched for patient, viral, donor, and transplant factors. Five-year advanced fibrosis-free survival in group 1 versus group 2 was 63% versus 28%, P < 0.001. Explant grade >4 was associated with increased HCV-related graft loss at 1 (6% versus 3%) and 5 (36% versus 14%) years post-LT (P = 0.003). On univariate and multivariate Cox regression analysis, predictors of advanced fibrosis were explant grade >4 (hazard ratio [HR] = 3.3, 95% confidence interval [CI] = 1.9-5.6, P < 0.001) donor age >50 (HR = 3.3, 95% CI = 1.9-5.7, P < 0.001) and viral load at LT of >158,730 IU/mL (HR = 1.8, 95% CI = 1.05-3.1, P = 0.03).

CONCLUSION

Explant histologic grade can identify patients requiring more aggressive monitoring and intervention for HCV recurrence post-LT.

Genes and hepatitis C: susceptibility, fibrosis progression and response to treatment

Hepatitis C virus contact and infection show three different phenotypes: spontaneous viral clearance (SVC), chronic hepatitis C (CHC) and sustained virological response (SVR) following antiviral treatment. Many factors, including genetics, influence the evolution of these three phenotypes. We performed a literature search (PubMed) up to 31 January 2010 without language restriction to identify relevant studies on genes and hepatitis C. Additional studies were sought by reviewing the reference lists of the identified articles. Meta-analysis (using Meta-disk 1.4) was conducted to evaluate the association of single nucleotide polymorphism (SNP) in the IL28B region and SVR. The candidate gene approach showed strong relationships between human leucocyte antigen class II (DQB1(*) 0301 and DRB1(*) 1101) and SVC. A cirrhosis risk score involving 7 SNPs has been validated recently. The set of odds ratios of studies demonstrated an association between SNP (rs12987960/rs8099917) in the IL28B and SVR in CHC treated with peginterferon plus ribavirin (OR: 4.6; 95% CI: 2.9-7.3). The overall distribution of protective allele correlated with ethnic differences in SVR (Asians, Europeans, Hispanic and Afro-Americans) together with SVC, but not with fibrosis stage or viral load. These polymorphisms did not influence SVR in very-easy-to-treat patients such as genotype 2/3, rapid virological responders or patients with acute hepatitis C. While the genetic fingerprint for fibrosis progression remains elusive, IL28b polymorphism predicts SVC and SVR. However, nearly half of patients achieving SVR did not show favourable genotype. Further genetic signals are warranted to complete the puzzle of factors influencing hepatitis C.

Combined effect of pro- and anti-inflammatory cytokine gene polymorphisms on susceptibility to liver cirrhosis in Tunisian HCV-infected patients

PURPOSE

Chronic hepatitis C progression is commonly attributed to the continuous activation of the immune response with an increased production of pro-inflammatory cytokines, leading to fibrosis and ultimately to cirrhosis. On the contrary, anti-inflammatory cytokines, mainly interleukin (IL)-10 have a modulatory effect on hepatic fibrogenesis. The association between individual polymorphisms within cytokine genes and hepatitis C outcome is often weak and non-informative. Interestingly, it has been demonstrated that a combination of specific genotypes may be a more significant and powerful approach for predicting disease risk.

AIM

This study is aimed at investigating the combined effect of single nucleotide polymorphism (SNP) in IL-18 (-607C/A, -137G/C), interferon (IFN)-γ (+874T/A) and IL-10 (-1082G/A) genes on cirrhosis risk in HCV-infected patients.

METHODS

Seventy-seven chronic hepatitis C Tunisian subjects were included in this study. The patients were divided into two groups: the first included 31 non-cirrhotic patients, and the second included 46 liver cirrhosis patients. IL-18 genotyping was performed using the PCR amplification and the restriction fragment length polymorphism analysis (RFLP). IFN-γ and IL-10 polymorphisms were analyzed using the allele-specific PCR (AS-PCR).

RESULTS

The combined high-risk genotype (IL-18 -607C/*, IL-18 -137G/*, IFN-γ +874T/*, IL-10 -1082A/A) frequency was compared between patients with and those without cirrhosis. Individuals were classified according the number of high-risk genotypes as follows: (0-2), patients with at most two high-risk genotypes; (3-4), patients with at least three of the high-risk genotypes. The logistic regression analysis showed that patients harboring 3-4 putative high-risk genotypes have a fivefold higher risk for developing cirrhosis in comparison to those harboring at most two high-risk genotypes (OR = 5.19; 95% CI = 1.49-18.05; p = 0.009).

CONCLUSION

Our study showed that the co-inheritance of IL-18, IFN-γ and IL-10 specific high-risk genotypes is associated with a greater risk for liver cirrhosis.