IL28B inhibits hepatitis C virus replication through the JAK-STAT pathway

Genetic variation in interleukin 28B and correlation with chronic hepatitis B virus infection in Saudi Arabian patients

BACKGROUND & AIMS

Several genome-wide association studies have shown that genetic variations in the chromosomal region containing interleukin-28B (IL28B) gene are associated with response to treatment in hepatitis C virus (HCV) infection. This study was conducted to examine the role of genetic variations in IL28B on disease progression in Saudi Arabian patients chronically infected with hepatitis B virus (HBV).

METHODS

The study included 1128 subjects divided into four categories; 304 clearance subjects, 518 inactive carriers, 212 active carriers and 94 cirrhosis/HCC.

RESULTS

Three single nucleotide polymorphisms (SNPs), rs12979860 (OR=1.307; 95% CI 1.046-1.634, χ2=5.57 and P=0.0183), rs12980275 (OR=0.642; CI 0.517-0.798, χ2=16.17 and P=0.0001) and rs8105790 (OR=0.746; CI 0.592-0.941, χ2=6.12 and P=0.0133), were found to be strongly associated with HBV clearance. The frequency of the G allele of rs12980275 and the C allele of rs8105790 were found to be more in clearance group than in patients and could contribute to protection against the disease. On the other hand, only rs12979860 showed significant difference in distribution when inactive group was compared to other groups (OR=1.285; CI 1.030-1.603, χ2=4.95, P=0.0261). No significant association was evident for any of the variants when active carriers were compared to cirrhosis/HCC patients. Haplotype analysis showed that a combination of A-T-T-G of rs12980275, rs8105790, rs8099917, and rs7248668, respectively, was associated with clearance of the virus (frequency=67.5% and P=0.015).

CONCLUSION

genetic variations in IL28B gene region may influence the clearance of HBV infection.

Role of IFN-ks, IFN-ks related genes and the DEPDC5 gene in Hepatitis B virus-related liver disease

Recent studies have associated genetic variation near the interleukin 28B (IL28B/IFN-λ3) gene with natural clearance of the hepatitis C virus (HCV) infection, and a common variant in the DEP domain containing 5 (DEPDC5) locus on chromosome 22 has been shown to affect susceptibility to hepatocellular carcinoma (HCC) in Japanese individuals with chronic HCV infection. This study was conducted to determine whether polymorphisms near or in interferon-lambda (IFN-λs) genes and their receptor genes such as interleukin 28 receptor, alpha (IL28RA) and interleukin 10 receptor, beta (IL10RB) as well as p21-activated kinases 4 (PAK4) and iron/zinc purple acid phosphatase-like protein (PAPL), which are locate upstream of IFN-λs, and lastly the DEPDC5 gene are associated with hepatitis B virus-related liver disease in Han Chinese. The study subjects included 507 normal healthy controls, 350 individuals with natural clearance of HBV and 792 HBV-infected patients. The patients were categorized into 157 inactive carriers (Case I), 216 active carriers (Case II), 111 cirrhotics (Case III) and 308 HCC patients (Case IV) subgroups. Seven single nucleotide polymorphisms (SNPs) were genotyped using the Matrix-assisted Laser Desorption/Ionisation mass spectrometric (MALDI-TOF MS) SNP genotyping assay. Rs423058 upstream of PAPL, rs2834167 in IL10RB and rs1012068 in DEPDC5 were associated with chronic HBV status, HBV natural clearance and the presence of HCC (P = 0.0004–0.024), respectively. PAPL, IL10RB and DEPDC5 polymorphisms have an impact on progression of HBV-related liver disease. However, IFN-λs genes as a tool to differentiate between different clinical courses of HBV infection were not useful in the Han Chinese population.

IFNL4 ss469415590 variant shows similar performance to rs12979860 as predictor of response to treatment against Hepatitis C Virus genotype 1 or 4 in Caucasians

Objectives

The rs12979860 variant, linked to IL28B gene, predicts sustained viral response (SVR) to pegylated-interferon/ribavirin (pegIFN/RBV) therapy in Hepatitis C Virus genotype 1 or 4 (HCV-1/4)-infected patients. Recently, a functional variant, ss469415590, in linkage disequilibrium (LD) with rs12979860, has been discovered. Our objective was to assess the value of ss469415590 to predict SVR to pegIFN/RBV in Caucasian HCV-1/4-infected individuals and to compare its performance with that of rs12979860.

Methods

272 Caucasian HCV-1/4-infected patients who completed a course of pegIFN/RBV were genotyped for both rs12979860 and ss469415590 markers. Logistic regression models including factors with univariate association with SVR and each genetic marker were elaborated. The area under the receiver operating-characteristic curve (AUROC) was calculated for each model and both were compared.

Results

Both markers were in LD (r² = 0.82). For rs12979860, 66 (64.0%) CC versus 56 (33.1%) T allele carriers achieved SVR (Adjusted OR = 4.156, 95%CI = 2.388–7.232, p = 4.647×10⁻⁷). For ss469415590, 66 (66.0%) TT/TT versus 56 (32.5%) –G allele carriers (Adjusted OR = 4.783, 95%CI = 2.714–8.428, p = 6.153×10⁻⁸) achieved SVR. The AUROC of the model including rs12979860 was 0.742 (95%CI = 0.672–0.813) and of that based on ss469415590 was 0.756 (95%CI = 0.687–0.826) (p = 0.780).

Conclusions

The ss469415590 variant shows an equivalent performance to predict SVR to pegIFN/RBV than the rs2979860 in Caucasian HCV-1/4-infected patients.

Network-based study reveals potential infection pathways of hepatitis-C leading to various diseases

Protein-protein interaction network-based study of viral pathogenesis has been gaining popularity among computational biologists in recent days. In the present study we attempt to investigate the possible pathways of hepatitis-C virus (HCV) infection by integrating the HCV-human interaction network, human protein interactome and human genetic disease association network. We have proposed quasi-biclique and quasi-clique mining algorithms to integrate these three networks to identify infection gateway host proteins and possible pathways of HCV pathogenesis leading to various diseases. Integrated study of three networks, namely HCV-human interaction network, human protein interaction network, and human proteins-disease association network reveals potential pathways of infection by the HCV that lead to various diseases including cancers. The gateway proteins have been found to be biologically coherent and have high degrees in human interactome compared to the other virus-targeted proteins. The analyses done in this study provide possible targets for more effective anti-hepatitis-C therapeutic involvement.

Kinetic differences in the induction of interferon stimulated genes by interferon-α and interleukin 28B are altered by infection with hepatitis C virus

Several genome-wide association studies (GWAS) have identified a genetic polymorphism associated with the gene locus for interleukin 28B (IL28B), a type III interferon (IFN), as a major predictor of clinical outcome in hepatitis C. Antiviral effects of the type III IFN family have previously been shown against several viruses, including hepatitis C virus (HCV), and resemble the function of type I IFN including utilization of the intracellular Janus kinase signal transducer and activator of transcription (JAK-STAT) pathway. Effects unique to IL28B that would distinguish it from IFN-α are not well defined. By analyzing the transcriptomes of primary human hepatocytes (PHH) treated with IFN-α or IL28B, we sought to identify functional differences between IFN-α and IL28B to better understand the roles of these cytokines in the innate immune response. Although our data did not reveal distinct gene signatures, we detected striking kinetic differences between IFN-α and IL28B stimulation for interferon stimulated genes (ISGs). While gene induction was rapid and peaked at 8 hours of stimulation with IFN-α in PHH, IL28B produced a slower, but more sustained increase in gene expression. We confirmed these findings in the human hepatoma cell line Huh7.5.1. Interestingly, in HCV-infected cells the rapid response after stimulation with IFN-α was blunted, and the induction pattern resembled that caused by IL28B.

CONCLUSION

The kinetics of gene induction are fundamentally different for stimulations with either IFN-α or IL28B in hepatocytes, suggesting distinct roles of these cytokines within the immune response. Furthermore, the observed differences are substantially altered by infection with HCV.

Individualization of chronic hepatitis C treatment according to the host characteristics

Hepatitis C virus (HCV) infection is a global health problem that affects more than 170 million people worldwide. It is a major cause of cirrhosis and hepatocellular carcinoma, making the virus the most common cause of liver failure and transplantation. The standard-of-care treatment for chronic hepatitis C (CHC) has been changed during the last decade and direct acting antiviral drugs have already been used. Besides, understanding of the pathogenesis of CHC has evolved rapidly during the last years and now several host factors are known to affect the natural history and response to treatment. Recent genome-wide association studies have shown the important role of interleukin-28B and inosine triphosphatase in HCV infection. The present review article attempts to summarize the current knowledge on the role of host factors towards individualization of HCV treatment.

Hepatitis C virus NS5A hijacks ARFGAP1 to maintain a phosphatidylinositol 4-phosphate-enriched microenvironment

Phosphatidylinositol 4-phosphate (PI4P) is well known to be upregulated during hepatitis C virus (HCV) replication. The role of PI4 kinases in HCV has been extensively investigated. Whether the PI4P phosphatase Sac1 is altered by HCV remains unclear. Here, we identified ARFGAP1 to be a novel host factor for HCV replication. We further show that Sac1 interacts with ARFGAP1 and inhibits HCV replication. The elevation of PI4P induced by HCV NS5A is abrogated when the coatomer protein I (COPI) pathway is inhibited. We also found an interaction between NS5A and ARFGAP1. Furthermore, we identified a conserved cluster of positively charged amino acids in NS5A critical for interaction between NS5A and ARFGAP1, induction of PI4P, and HCV replication. Our data demonstrate that ARFGAP1 is a host factor for HCV RNA replication. ARFGAP1 is hijacked by HCV NS5A to remove COPI cargo Sac1 from the site of HCV replication to maintain high levels of PI4P. Our findings provide an additional mechanism by which HCV enhances formation of a PI4P-rich environment.

IMPORTANCE

PI4P is enriched in the replication area of HCV; however, whether PI4P phosphatase Sac1 is subverted by HCV is not established. The detailed mechanism of how COPI contributes to viral replication remains unknown, though COPI components were hijacked by HCV. We demonstrate that ARFGAP1 is hijacked by HCV NS5A to remove COPI cargo Sac1 from the HCV replication area to maintain high-level PI4P generated by NS5A. Furthermore, we identify a conserved cluster of positively charged amino acids in NS5A, which are critical for interaction between NS5A and ARFGAP1, induction of PI4P, and HCV replication. This study will shed mechanistic insight on how other RNA viruses hijack COPI and Sac1.

IL28RA polymorphism (rs10903035) is associated with insulin resistance in HIV/HCV-coinfected patients

Hepatitis C virus (HCV) infection is associated with insulin resistance (IR), although mechanisms leading to IR in these patients are not completely understood. The aim of this study was to evaluate the association of interleukin 28B (IL28B) and interleukin 28 receptor alpha (IL28RA) polymorphisms with IR among human immunodeficiency virus (HIV)/HCV-coinfected patients. We carried out a cross-sectional study on 203 patients. IL28B (rs8099917) and IL28RA (rs10903035) polymorphisms were genotyped by GoldenGate(®) assay. IR was defined as homeostatic model assessment (HOMA) values ≥3.00. Univariate and multivariate generalized linear models (GLM) were used to compare HOMA values and the percentage of patients with IR according to IL28B and IL28RA genotypes. In total, 32% (n = 65/203) of the patients had IR. IL28B rs8099917 TT was not significantly associated with HOMA values and IR. In contrast, rs10903035 AA was significantly associated with high HOMA values taking into account all patients (P = 0.024), as well as the subgroups of patients with significant fibrosis (P = 0.047) and infected with HCV genotype 3 (P = 0.024). Additionally, rs10903035 AA was significantly associated with IR (HOMA ≥3.00) in all patients (adjusted odds ratio (aOR) = 2.02; P = 0.034), in patients with significant fibrosis (aOR = 2.86; P = 0.039) and HCV genotype 3 patients (aOR = 4.89; P = 0.031). In conclusions, IL28RA polymorphism (rs10903035) seems to be implicated in the glucose homeostasis because AA genotype increases the likelihood of IR, but this association was different depending on hepatic fibrosis and HCV genotype.

Genetic polymorphisms of the IFNλ genes are associated with biochemical features in Han Chinese with HCV infection from Yunnan Province, China

Hepatitis C virus (HCV) is the pathogenic factor for hepatitis C disease, which could lead to chronic or serious hepatic diseases. Previous studies have identified that the IL28B gene polymorphisms were associated with therapeutic effect and viral clearness of HCV patients. We aimed to test whether genetic polymorphisms of three IFNλ genes (IL28A, IL28B and IL29) are associated with HCV infection in Han Chinese. We collected whole blood of 261 HCV infectious patients without any therapy and 265 matched normal controls from Yunnan Province. Among these subjects, 28.4% (74/261) of HCV patients and 26.8% (71/265) of controls were male. Ten SNPs (rs8099917, rs10853728, rs11883177, rs12980602, rs4803224, rs11671087, rs11665818, rs8108008, rs7248931, and rs30461), which covered the whole region of the IL28A, IL28B, and IL29 genes, were genotyped. Our results showed that there was no association between genotypes and alleles of the IFNλ gene polymorphisms and HCV infection. One haplotype (TGCTGTGGAT), which was consisted of ten SNPs, showed a significantly higher frequency in HCV patients (11/522 = 2.1%) than in controls (1/530 = 0.2%) (P = 0.003). We performed association analyses for biochemical features and genotype of each SNP, and found that HCV patients with certain genotypes of some SNPs had a higher level of the ALT/AST ratio and total blood bilirubin (TBIL) compared to healthy controls. Our results suggested the IFNλ gene polymorphisms might be associated with clinical features of HCV patients from Yunnan Province, China.

Interaction of IFNL3 with insulin resistance, steatosis and lipid metabolism in chronic hepatitis C virus infection

Metabolic changes are inextricably linked to chronic hepatitis C (CHC). Recently polymorphisms in the IFNL3 (IL28B) region have been shown to be strongly associated with spontaneous and treatment induced recovery from hepatitis C virus (HCV) infection. Further, circumstantial evidence suggests a link between IFNL3 single nucleotide polymorphisms and lipid metabolism, steatosis and insulin resistance in CHC. The emerging picture suggests that the responder genotypes of IFNL3 polymorphisms are associated with a higher serum lipid profile, and less frequent steatosis and insulin resistance. This review analyzes the current data regarding this interaction and its meaning for HCV pathogenesis and disease progression.

The AMPK-related kinase SNARK regulates hepatitis C virus replication and pathogenesis through enhancement of TGF-β signaling

BACKGROUND & AIMS

Hepatitis C virus (HCV) is a major cause of chronic liver disease worldwide. The biological and therapeutic importance of host cellular cofactors for viral replication has been recently appreciated. Here we examined the roles of SNF1/AMP kinase-related kinase (SNARK) in HCV replication and pathogenesis.

METHODS

The JFH1 infection system and the full-length HCV replicon OR6 cell line were used. Gene expression was knocked down by siRNAs. SNARK mutants were created by site-directed mutagenesis. Intracellular mRNA levels were measured by qRT-PCR. Endogenous and overexpressed proteins were detected by Western blot analysis and immunofluorescence. Transforming growth factor (TGF)-β signaling was monitored by a luciferase reporter construct. Liver biopsy samples from HCV-infected patients were analyzed for SNARK expression.

RESULTS

Knockdown of SNARK impaired viral replication, which was rescued by wild type SNARK but not by unphosphorylated or kinase-deficient mutants. Knockdown and overexpression studies demonstrated that SNARK promoted TGF-β signaling in a manner dependent on both its phosphorylation and kinase activity. In turn, chronic HCV replication upregulated the expression of SNARK in patients. Further, the SNARK kinase inhibitor metformin suppressed both HCV replication and SNARK-mediated enhancement of TGF-β signaling.

CONCLUSIONS

Thus reciprocal regulation between HCV and SNARK promotes TGF-β signaling, a major driver of hepatic fibrogenesis. These findings suggest that SNARK will be an attractive target for the design of novel host-directed antiviral and antifibrotic drugs.

IL-29 enhances Toll-like receptor-mediated IL-6 and IL-8 production by the synovial fibroblasts from rheumatoid arthritis patients

INTRODUCTION

We previously reported that IL-29, a newly described member of interferon (IFN) family, was overexpressed in blood and synovium of rheumatoid arthritis (RA) patients and triggered proinflammatory cytokine IL-6 and IL-8 mRNA expression in RA synovial fibroblasts (RA-FLS). This suggests that IL-29 has an important role in synovial inflammation. Toll-like receptors (TLRs) also activate RA-FLS to produce inflammatory mediators including tumor necrosis factor α (TNF-α) and IL-1β in RA-FLS. Since the TLR family plays an early role in the innate immune response and the subsequent induction of the adaptive immune response, we hypothesize that IL-29 interacts with TLRs in RA inflammation. This study aimed to investigate the effect of IL-29 on TLR-mediated proinflammatory cytokine production in RA-FLS.

METHODS

The mRNA level of IL-29 receptors (IL-28Rα and IL-10R2) in RA-FLS was determined by semi-quantitative RT- PCR. IL-6 and IL-8 mRNA expressions in RA-FLS were evaluated by real-time PCR after pre-incubation with IL-29 and subsequent stimulation with peptidoglycan (PGN, TLR2 ligand), or polycytidylic acid (poly(I:C), TLR3 ligand), or lipopolysaccharide (LPS, TLR4 ligand) . The production of TLR2, 3, and 4 in RA-FLS after IL-29 stimulation was also assessed by real-time PCR and flow cytometry. IL-29 mRNA and protein expression in RA-FLS after stimulation with PGN, poly(I:C), or LPS were measured by real-time PCR and enzyme-linked immunosorbent assay (ELISA), respectively.

RESULTS

The IL-29 receptor complex (IL-28Rα and IL-10R2) was identified in RA-FLS. IL-29 enhanced TLR-mediated IL-6 and IL-8 expression in RA-FLS. IL-29 upregulated expression of TLR2, 3 and 4 in RA-FLS. Exposure to PGN, poly(I:C) or LPS triggered IL-29 production by RA-FLS.

CONCLUSIONS

We show for the first time that IL-29 enhances TLR-induced proinflammatory cytokine production in RA-FLS via upregulation of TLRs.

Understanding the molecular mechanism(s) of hepatitis C virus (HCV) induced interferon resistance

Hepatitis C virus (HCV) is one of the foremost causes of chronic liver disease affecting over 300 million globally. HCV contains a positive-stranded RNA of ~9600 nt and is surrounded by the 5' and 3'untranslated regions (UTR). The only successful treatment regimen includes interferon (IFN) and ribavirin. Like many other viruses, HCV has also evolved various mechanisms to circumvent the IFN response by blocking (1) downstream signaling actions via STAT1, STAT2, IRF9 and JAK-STAT pathways and (2) repertoire of IFN Stimulatory Genes (ISGs). Several studies have identified complex host demographic and genetic factors as well as viral genetic heterogeneity associated with outcomes of IFN therapy. The genetic predispositions of over 2000 ISGS may render the patients to become resistant, thus identification of such parameters within a subset of population are necessary for management corollary. The ability of various HCV genotypes to diminish IFN antiviral responses plays critical role in the establishment of chronic infection at the acute stage of infection, thus highlighting importance of the resistance in HCV treated groups. The recently defined role of viral protein such as C, E2, NS3/NS4 and NS5A proteins in inducing the IFN resistance are discussed in this article. How the viral and host genetic composition and epistatic connectivity among polymorphic genomic sites synchronizes the evolutionary IFN resistance trend remains under investigation. However, these signals may have the potential to be employed for accurate prediction of therapeutic outcomes. In this review article, we accentuate the significance of host and viral components in IFN resistance with the aim to determine the successful outcome in patients.

Therapy of chronic hepatitis C virus infection in the era of direct-acting and host-targeting antiviral agents

OBJECTIVES

Chronic hepatitis C virus (HCV) infection represents a leading worldwide medical and social problem. The expanding knowledge of HCV lifecycle has led to the development of novel antiviral agents that: a) specifically target a viral function (direct-acting antivirals), or b) specifically inhibit viral replication. The present review describes the novel anti-HCV drugs that have been better studied at the time of this writing and the current two types of treatment, namely interferon-based and interferon-free regimens. In addition, predictive factors, virological responses, side-effects, and resistance mechanisms of the novel agents are summarized.

CONCLUSIONS

The introduction of novel antiviral agents is remarkably changing the therapeutic combinations aimed at improving virological responses both for easy-to-cure and difficult-to-treat patients. Since additional, effective drugs are under advanced development, it seems reasonable to expect that further therapeutic and prognostic improvements will be achieved in the near future.

Polymorphism Near the Interleukin-28B Gene and Anti-Hepatitis C Viral Response

In a recent genome-wide association study, single nucleotide polymorphisms (SNPs) located near the interleukin-28B gene (IL28B), which encodes type III interferon (IFN) λ3, were shown to be strongly associated with a viral response to pegylated IFNα (PEG-IFNα) and ribavirin (RBV) combination therapy and spontaneous viral clearance in patients chronically and acutely infected with hepatitis C virus (HCV), respectively. The global distribution of allele frequencies shows a remarkable pattern, in which a favorable allele is nearly fixed in East Asia, has an intermediate frequency in Europe, and is least frequent in Africa. Although the underlying mechanisms responsible for viral responses associated with IL28B SNPs have not been completely elucidated, IFN-stimulated gene expression in patients with unfavorable IL28B genotypes tends to be high at baseline and is insufficiently induced by exogenous IFN administration, resulting in poor treatment outcomes. Clinically, triple therapy with PEG-IFNα/RBV together with direct-acting antiviral agents (DAAs) is currently used to treat chronic hepatitis C as a first-line therapy. Although the predictive power of IL28B status may be attenuated, the IL28B genotype will remain relevant to the outcomes of DAA therapy when used in combination with PEG-IFNα as a backbone. Even with the introduction of IFN-free therapies with a new class of highly effective DAAs, IL28B SNPs are still useful predictors of treatment outcomes and can be used to individualize treatment strategies to maximize cost-effectiveness and identify patients at risk of being refractory to treatment. This review summarizes the current understanding of the clinical significance and role of IL28B in HCV infection and response to therapy.

IL28B genotype and the expression of ISGs in normal liver

BACKGROUND & AIMS

Both polymorphisms in the IL28B gene locus and ISG expression levels are associated with the outcome of hepatitis C virus (HCV) infection. The two are also interrelated, although the mechanism is unknown. Favourable CC genotype at rs12979860 expresses lower baseline ISG levels and responds better to treatment than unfavourable CT and TT genotypes. Little is known about this relationship in normal, uninfected liver. This study sought to explore this relationship.

METHODS

Normal human liver specimens (64) and HCV positive human liver specimens (95) were genotyped for IL28B rs12979860 C > T. mRNA levels of ISGs and other relevant genes were studied by qPCR.

RESULTS

Most studied ISGs had significantly different expression by IL28B genotype in normal liver. CC genotype expressed the highest levels, CT intermediate and TT the lowest. This is opposite to the pattern seen in HCV patients. Principal component analysis of IL28B genotype and ISG expression further revealed a distinct set of genes correlated with the C allele (ISG15, HTATIP2, LGALS3BP, IRF2 and BCL2) and T allele (IFNα, β, γ, λ3 and CD80).

CONCLUSION

A subset of ISGs was found to be differentially expressed in normal liver by IL28B genotype. This suggests a relationship between IL28B genotype and gene expression before HCV infection.

Clinico-pathological significance of hepatitis C virus core antigen levels in chronic infection

Hepatitis C virus core antigen (HCVcoreAg) may be measured in serum with a sensitive, recently validated assay. Beyond its value as a marker of viral infection, there are little data on its relation with clinical, histological, and virological parameters. In this study, the significance of HCVcoreAg levels was studied in a prospective cohort of 114 patients with chronic hepatitis C. HCVcoreAg was measured by a commercial chemiluminescent microparticle immunoassay. Clinical and virological data included quantitative HCV-RNA, HCV genotype, ALT, GGT, IL28B rs12979860 polymorphism as well as liver histology parameters. HCVcoreAg levels were correlated significantly with HCV-RNA (r=0.56; P<0.0001) but also with ALT levels (r=0.258; P<0.01) and liver necroinflammatory activity (r=0.205; P<0.04). Patients harbouring HCV genotype 3 showed lower levels of HCVcoreAg than both genotype 1 and two patients. In genotype 3, a direct correlation between steatosis and HCVcoreAg was found. Levels of HCVcoreAg also varied according to the IL28B genotype. These data suggest that the evaluation of HCVcoreAg serum levels may provide relevant data for the baseline clinical evaluation of chronic hepatitis C patients. HCVcoreAg serum levels may be a useful tool to further the understanding of chronic hepatitis C pathobiology.

Induction of interferon-λ contributes to Toll-like receptor-3-activated hepatic stellate cell-mediated hepatitis C virus inhibition in hepatocytes

There is limited information about the role of hepatic stellate cells (HSC) in liver innate immunity against hepatitis C virus (HCV). We thus examined whether HSC can produce antiviral factors that inhibit HCV replication in human hepatocytes. HSC expressed functional Toll-like receptor 3 (TLR-3), which could be activated by its ligand, polyinosine-polycytidylic acid (poly I:C), leading to the induction of interferon-λ (IFN-λ) at both mRNA and protein levels. TLR-3 signalling of HSC also induced the expression of IFN regulatory factor 7 (IRF-7), a key regulator of IFN signalling pathway. When HCV JFH-1-infected Huh7 cells were co-cultured with HSC activated with poly I:C or incubated in media conditioned with supernatant (SN) from poly I:C-activated HSC, HCV replication was significantly suppressed. This HSC SN action on HCV inhibition was mediated through IFN-λ, which was evidenced by the observation that antibody to IFN-λ receptors could neutralize the HSC-mediated anti-HCV effect. The role of IFN-λ in HSC-mediated anti-HCV activity is further supported by the observation that HSC SN treatment induced the expression of IRF-7 and IFN-stimulated genes (ISGs), OAS-1 and MxA in HCV-infected Huh7 cells. These observations indicate that HSC may be a key regulatory bystander, participating in liver innate immunity against HCV infection using an IFN-λ-dependent mechanism.

Rs12979860 and rs8099917 single nucleotide polymorphisms of interleukin-28B gene: simultaneous genotyping in caucasian patients infected with hepatitis C virus

INTRODUCTION

Recent studies have demonstrated the role of the interleukin 28B (IL28B) polymorphisms in predicting treatment induced and spontaneous clearance from Hepatitis C virus (HCV) infection, suggesting the possibility of tailored therapy in HCV infected patients. Genome-wide association studies have shown that single nucleotide polymorphisms (SNPs) near IL 28B gene on chromosome 19 are strong predictors of sustained virologic response (SVR) to pegylated interferon and ribavirin. This study was aimed at analyzing the co-prevalence of two common and clinically significant SNPs in a cohort of Ligurian patients.

METHODS

Two SNPs (rs12979860, rs8099917) were genotyped in the IL28B locus from 175 DNA samples collected from HCV-infected consecutive patients in a Laboratory of Liguria Region, northern Italy. A real-time polymerase chain reaction in a Corbett Research Termocycler (Rotor Gene 3000A) by fluorescent probes (Fast Set IL 28B, Arrow Diagnostics) was used for the detection, according to the manufacturer's instructions.

RESULTS

Carriers of rs12979860CT genotype predominated (87/175, 50%), homozygotes for allele C were 68/175 (39%) and the remaining were homozygotes for IFN-resistant allele T (11%). As for the rs8099917 SNP, genotypes were thus distributed: 96/175 (55%) carried the rs8099917 TT genotype, whereas 70/175 (40%) and 9/175 (5%), were heterozygotes or homozygotes for the G allele. The variants rs12979860CC and rs8099917TT were found in 39% and 54% of overall patients with HCV genotype 1, respectively. The combined assessment of examined SNPs resulted in three most prevalent genotypes (rs12979860CC/rs8099917TT, rs12979860CT/rs8099917TG and rs12979860CT/rs8099917TT) with a frequency of 35%, 31% and 18%, respectively.

DISCUSSION

Recent findings demonstrated that in carriers of rs12979860CT the determination of additional genotype of rs8099917 SNP could significantly improve the prediction of SVR. In our study cohort carriers of rs12979860CT represented 50% of all patients, who could take advantage with respect to SVR prediction by further determination of the rs8099917 SNP. The simultaneous genotyping of two IL28B SNPs should thus be recommended in HCV infected patients prior to treatment initiation.

Albumin fusion of interleukin-28B: production and characterization of its biological activities and protein stability

The cytokine interleukin-28B (IL-28B) has potential antiviral properties and regulatory roles in adaptive cellular immunity. A genome-wide association study identified a single nucleotide polymorphism near the IL-28B gene that strongly predicts response to hepatitis C treatment with interferon and ribavirin. In this study, we produced human serum albumin (HSA) fused to interleukin-28B (HSA-IL28B) in an attempt to determine the effects of albumin fusion on anti-Hepatitis C virus (HCV) activity and protein stability. HSA-IL28B was expressed at high levels in the yeast expression system we used and was easily purified. The biological activities of IL-28B were only retained when HSA was fused at the N-terminus. Compared with the native IL-28B, HSA-IL28B showed improved protein stability. HSA-IL28B inhibited HCV infection through the membrane receptors IL28R1 and IL10R2. Additionally, we demonstrated that HSA-IL28B was able to induce interferon-stimulated genes, phosphorylate intracellular STAT1, and act in restricted cell types. Our findings highlight the potential clinical applications of the fusion protein during virus infection and for immune regulation.

Future classes of hepatitis C virus therapeutic agents

Recent advances in understanding of the molecular characteristics of the hepatitis C virus have led to the development of novel antiviral therapeutics. Direct-acting antivirals are designed to inhibit viral targets, whereas host-targeted antivirals block host factors that are used by the virus for its own life cycle. The rapid development of agents in multiple classes has led to the promise of shorter therapy duration, an improved side effect profile, and eventually interferon-sparing regimens. This article reviews novel hepatitis C virus therapeutics in development, including mechanism of action, efficacy, and adverse effects.

Interleukin-28B rs12979860C/T and rs8099917T/G contribute to spontaneous clearance of hepatitis C virus in Caucasians

Two single nucleotide polymorphisms rs12979860C/T and rs8099917T/G around interleukin-28B (IL28B) locus have been extensively investigated in their association with hepatitis C virus (HCV) spontaneous clearance. However, with the variable and even inconsistent results, it is necessary to conduct a meta-analysis. A literature search was conducted to seek articles about genetic variation of IL28B and spontaneous clearance of HCV. Odds ratio with 95% confidential interval were calculated to estimate their relationship. Furthermore, meta-regression analysis was performed to search for potential affective factors. A total of 8 studies including 2460 patients with chronic HCV infection and 1052 individuals with spontaneous HCV clearance met inclusion criteria, in which seven studies describing rs12979860 and three studies describing rs8099917. Analysis performed in Caucasian populations indicated that rs12979860CC and rs8099917TT contributed to HCV spontaneous clearance in both dominant model (CC vs. CT+TT, P<1×10(-4); TT vs. TG+GG, P<10(-4), respectively) and co-dominant model (CC vs. CT, P<1×10(-4), CC vs. TT, P<1×10(-4); TT vs. TG, P<10(-4), TT vs. GG, P=0.012, respectively). Meta-regression analysis suggested that male proportion (P=1×10(-5)) and mean age (P=1×10(-3)) might weaken the effect of rs12979860CC, but HCV genotype 1/4 (P=4×10(-4)) might contribute to it. IL28B rs12979860CC and rs8099917TT genotypes contribute to spontaneous HCV clearance in Caucasians.

IL-28B (IFN-λ3) and IFN-α synergistically inhibit HCV replication

Genetic variation in the IL-28B (interleukin-28B; interferon lambda 3) region has been associated with sustained virological response (SVR) rates in patients with chronic hepatitis C treated with peginterferon-α and ribavirin. However, the mechanisms by which polymorphisms in the IL-28B gene region affect host antiviral responses are not well understood. Using the HCV 1b and 2a replicon system, we compared the effects of IFN-λs and IFN-α on HCV RNA replication. The anti-HCV effect of IFN-λ3 and IFN-α in combination was also assessed. Changes in gene expression induced by IFN-λ3 and IFN-α were compared using cDNA microarray analysis. IFN-λs at concentrations of 1 ng/mL or more exhibited concentration- and time-dependent HCV inhibition. In combination, IFN-λ3 and IFN-α had a synergistic anti-HCV effect; however, no synergistic enhancement was observed for interferon-stimulated response element (ISRE) activity or upregulation of interferon-stimulated genes (ISGs). With respect to the time course of ISG upregulation, the peak of IFN-λ3-induced gene expression occurred later and lasted longer than that induced by IFN-α. In addition, although the genes upregulated by IFN-α and IFN-λ3 were similar to microarray analysis, interferon-stimulated gene expression appeared early and was prolonged by combined administration of these two IFNs. In conclusion, IFN-α and IFN-λ3 in combination showed synergistic anti-HCV activity in vitro. Differences in time-dependent upregulation of these genes might contribute to the synergistic antiviral activity.

Interferon-lambda (IFN-λ) induces signal transduction and gene expression in human hepatocytes, but not in lymphocytes or monocytes

This study compared the ability of IFN-α and IFN-λ to induce signal transduction and gene expression in primary human hepatocytes, PBLs, and monocytes. IFN-α drug products are widely used to treat chronic HCV infection; however, IFN-α therapy often induces hematologic toxicities as a result of the broad expression of IFNARs on many cell types, including most leukocytes. rIFN-λ1 is currently being tested as a potential alternative to IFN-α for treating chronic HCV. Although IFN-λ has been shown to be active on hepatoma cell lines, such as HepG2 and Huh-7, its ability to induce responses in primary human hepatocytes or leukocytes has not been examined. We found that IFN-λ induces activation of Jak/STAT signaling in mouse and human hepatocytes, and the ability of IFN-λ to induce STAT activation correlates with induction of numerous ISGs. Although the magnitude of ISG expression induced by IFN-λ in hepatocytes was generally lower than that induced by IFN-α, the repertoire of regulated genes was quite similar. Our findings demonstrate that although IFN-α and IFN-λ signal through distinct receptors, they induce expression of a common set of ISGs in hepatocytes. However, unlike IFN-α, IFN-λ did not induce STAT activation or ISG expression by purified lymphocytes or monocytes. This important functional difference may provide a clinical advantage for IFN-λ as a treatment for chronic HCV infection, as it is less likely to induce the leukopenias that are often associated with IFN-α therapy.

Combinations of lambda interferon with direct-acting antiviral agents are highly efficient in suppressing hepatitis C virus replication

The clinical efficacy of a pegylated form of human lambda 1 interferon (IFN-λ1; also referred to herein as lambda) has been demonstrated in patients chronically infected with hepatitis C virus (HCV) representing genotypes 1 through 4. In these proof-of-concept studies, lambda showed an improved safety profile compared to the pegylated form of alpha interferon (referred to herein as alfa). In the study described in this report, an assessment of the in vitro antiviral activity of type III IFNs toward different HCV replicons revealed that the unpegylated recombinant form of IFN-λ1 (rIFN-λ1) exerted the most robust effect, while rIFN-λ3 exhibited greater activity than rIFN-λ2. More importantly, cross-resistance to rIFN-λ1 was not observed in replicon cell lines known to have reduced susceptibility to investigational direct-acting antiviral (DAA) agents targeting the essential HCV nonstructural protein NS3, NS5A, or NS5B. When combined with either rIFN-α, the NS3 protease inhibitor (NS3 PI) asunaprevir (ASV), the NS5A replication complex inhibitor (NS5A RCI) daclatasvir (DCV), or the NS5B polymerase site I inhibitor (NS5B I) BMS-791325, rIFN-λ1 displayed a mixture of additive and synergistic effects. In three-drug combination studies, inclusion of lambda with ASV and DCV also yielded additive to synergistic effects. In line with these observations, it was demonstrated that a regimen that used a combination of rIFN-λ1 with one or two DAAs was superior to an IFN-free regimen in clearing HCV RNA in genotype 1a cell lines representing wild-type and NS3 protease inhibitor-resistant sequences. Overall, these data support further clinical development of lambda as part of alternative combination treatments with DAAs for patients chronically infected with HCV.

The association of IL28B polymorphism and graft survival in patients with hepatitis C undergoing liver transplantation

Hepatitis C virus (HCV) infection is the leading cause of liver transplantation (LT) in Western countries. Polymorphism in the IL28B gene region has a major impact on the natural history and response to antiviral treatment in HCV. We investigated whether IL28B polymorphism was associated with graft survival in patients with or without HCV undergoing LT. 1,060 adult patients (age >18 years) underwent LT between years 2000 and 2008. Patients with previous LT, living donor LT and patients dying or requiring retransplants within 30 days of LT were excluded. DNA samples of 620 (84%) recipients and 377 (51%) donors were available for genotyping of IL28B rs12979860C>T. Donor IL28B genotypes had no significant differences in graft survival irrespective of HCV status. There was no difference in graft outcome in the non-HCV cohort (n = 293) based on recipient IL28B genotype. In the HCV group (n = 327), recipients with CC or CT genotype had better graft survival compared to TT genotype (62% vs. 48%, p = 0.02). HCV recipients with CC or CT genotype had delayed time to clinically relevant HCV recurrence compared to TT (10.4 vs. 6.7 months, p = 0.002). The beneficial effect of the CC/CT genotype on HCV recurrence and graft survival was independent of antiviral treatment. In conclusion, our study demonstrated that in contrast to donor IL28B genotype recipient IL28B was associated with graft survival and clinically relevant HCV recurrence in HCV infected recipients. No effect of IL28B genotype was manifest in non-HCV LT recipients.

SOCS1 abrogates IFN's antiviral effect on hepatitis C virus replication

Suppressor of cytokine signaling 1 (SOCS1) and suppressor of cytokine signaling 3 (SOCS3) have been thought to block type I interferon (IFN) signaling. We have previously reported that SOCS3 suppresses HCV replication in an mTOR-dependent manner. However, the relationship between SOCS1 and HCV replication remains unclear. Here, we found that overexpression of SOCS1 alone did not have an effect on HCV RNA replication. However, suppression of HCV replication by IFN-α was rescued by SOCS1 overexpression. The upregulation of HCV replication by SOCS1 overexpression in the presence of IFN is likely a result of the impairment of IFN signaling by SOCS1 and subsequent induction of ISGs. Knockdown of SOCS1 alone with specific shRNA enhanced the antiviral effect of IFN compared with negative control. Thus, SOCS1 acts as a suppressor of type I IFN function against HCV.

Negative predictive value of IL28B, SLC28A2, and CYP27B1 SNPs and low RBV plasma exposure for therapeutic response to PEG/IFN-RBV treatment

OBJECTIVES

The response rate to treatment of chronic hepatitis C virus-genotype 1 and 4 infections was recently found to be strongly influenced by many polymorphisms. The aim of our study was to carry out an integrated analysis of the effects of polymorphisms and ribavirin (RBV) plasma exposure on outcome.

METHODS

The retrospective analysis included 174 patients. IL28B, CYP27B1, SLC29A1, SLC28A3, and SLC28A2 polymorphisms were genotyped and tested for association with sustained virological response. The impact of RBV plasma exposure during the first 3 months of therapy on outcome was also investigated.

RESULTS

Considering patients infected by hepatitis C virus-1/4, 3 polymorphisms (IL28B rs8099917TT, CYP27B1 rs4646536TT, and CNT2 rs11854484TT) were associated with sustained virological response. The number of negative variant allele and low RBV exposure were correlated to percentage increasing to therapy failure, suggesting some degree of cumulative effect of the 4 factors. A cutoff of 2.5 μg/mL of RBV was found to be associated with outcome (area under ROC [AUROC] curve = 0.64, sensitivity = 55.0%, and specificity = 71.2%, P = 0.020). In multivariate logistic regression analyses, each variant allele and RBV plasma exposure cutoff were independently associated with outcome.

CONCLUSIONS

In this study, we found that additional polymorphisms and RBV plasma exposure are also able to influence the achievement of response. Regardless of the magnitude of RBV pharmacokinetic exposure, the negative predictive value of the polymorphisms here investigated is much stronger than the positive one.

IL28B genetic variation and hepatitis C virus-specific CD4(+) T-cell responses in anti-HCV-positive blood donors

Epidemiological, viral and host factors are associated with the outcome of hepatitis C virus (HCV) infection, and strong host immune responses against HCV favour viral clearance. Recently, genome-wide association studies have shown a strong correlation between single-nucleotide polymorphisms (SNPs) near the interleukin-28B (IL28B) gene and spontaneous or treatment-induced HCV clearance. We have investigated whether protective IL28B genetic variants are associated with HCV-specific T-cell responses among Spanish blood donors. The rs12979860 IL28B haplotype was determined in 69 anti-HCV-positive blood donors (21 HCV RNA negative and 48 HCV RNA positive) and 30 seronegative donors. In all cases, HCV-specific CD4(+) T-cell responses to HCV recombinant proteins (core, NS3 and NS3 helicase) were assessed by ex vivo interferon-γ ELISpot assay. The rs12979860-CC genotype was highly overrepresented in donors with spontaneous HCV clearance when compared to those with chronic infection (76.2%vs 29.2%, P < 0.001; odds ratio, 7.77; 95% confidence interval, 2.4-25.3, P < 0.001). HCV-specific CD4(+) T-cell responses were detected in 16 (76.2%) spontaneous resolvers especially towards nonstructural proteins, but with no correlation with IL28B genotype. Chronic individuals had a significantly lower overall T-cell response again irrespective of IL28B genotype. When spontaneous resolvers and chronic individuals were stratified according to their IL28B genotype, significantly stronger T-cell responses were only observed among those with non-CC haplotypes. Although the protective rs12979860 IL28B CC genotype is associated with spontaneous HCV clearance, stronger CD4(+) T-cell responses towards NS3 were only evident among those with non-CC haplotypes.

IL28B polymorphisms as a pretreatment predictor of response to HCV treatment

Genome-wide association studies have identified polymorphisms located near the gene encoding IL28B, which turned out to be the best predictor of response to pegylated interferon plus ribavirin for chronic hepatitis C virus (HCV) genotype 1 infection. This association was extended to spontaneous clearance of HCV, suggesting shared mechanisms of treatment and natural control of this virus. In addition to the biologic implications for innate immunity and HCV, a variety of clinical studies have suggested possible translation to a useful genetic test for practitioners. This article reviews the discovery, biology, and potential clinical applications that have stemmed from the seminal observation that IL28B polymorphisms are a main predictor of HCV clearance.

Interferon stimulated genes and hepatitis C virus infection

Hepatitis C Virus (HCV) is a major cause of chronic liver disease worldwide. In addition to viral and environmental behavioral factors, host genetic diversity is believed to contribute to the spectrum of the disease. The sequencing of the human genome, together with the development of high-throughput technologies that measure the function of the genome, have afforded unique opportunities to develop profiles that can distinguish and classify discrete subsets of a disease and predict a response to therapy. In 2011, 2 directly acting antivirals (DAAs) have been approved for chronic HCV genotype 1 infection, Telaprevir and Boceprevir, and open a new area for HCV therapy. These 2 NS3/4 protease inhibitors are given in combination with pegylated interferon and ribavirin. Several DAAs are in development. Since a significant number of patients will fail to respond to treatment, or will have significant side effects, it is of major interest to predict a response to treatment as early as possible. Several studies are ongoing to identify biomarkers that could predict treatment outcome in patients with hepatitis C before treatment. Many of the genes upregulated in the liver between nonresponders and responders codes molecules secreted in the serum and can constitute a logical functional approach for the development of serum markers predictors of response to treatment. In the next future, further studies have several challenges to fight. First, large prospective cohorts with well phenotyped patients and appropriate tissue controls are needed. For response to treatment, the appropriate definition of sustained response and the same treatment regimen have to be addressed. Furthermore, improved technology and analytical procedures and the use of large numbers of patients for validation are needed.

IL-29 is the dominant type III interferon produced by hepatocytes during acute hepatitis C virus infection

Early, vigorous intrahepatic induction of interferon (IFN)-stimulated gene (ISG) induction is a feature of hepatitis C virus (HCV) infection, even though HCV inhibits the induction of type I IFNs in vitro. To identify the cytokines and cells that drive ISG induction and mediate antiviral activity during acute HCV infection, type I and III IFN responses were studied in (1) serial liver biopsies and plasma samples obtained from 6 chimpanzees throughout acute HCV infection and (2) primary human hepatocyte (PHH) cultures upon HCV infection. Type I IFNs were minimally induced at the messenger RNA (mRNA) level in the liver and were undetectable at the protein level in plasma during acute HCV infection of chimpanzees. In contrast, type III IFNs, in particular, interleukin (IL)-29 mRNA and protein, were strongly induced and these levels correlated with ISG expression and viremia. However, there was no association between intrahepatic or peripheral type III IFN levels and the outcome of acute HCV infection. Infection of PHH with HCV recapitulated strong type III and weak type I IFN responses. Supernatants from HCV-infected PHH cultures mediated antiviral activity upon transfer to HCV-replicon-containing cells. This effect was significantly reduced by neutralization of type III IFNs and less by neutralization of type I IFNs. Furthermore, IL-29 production by HCV-infected PHH occurred independently from type I IFN signaling and was not enhanced by the presence of plasmacytoid dendritic cells.

CONCLUSION

Hepatocyte-derived type III IFNs contribute to ISG induction and antiviral activity, but are not the principal determinant of the outcome of HCV infection.

Natural history and clinical response: "it's the virus, stupid, or is it the host?"

A major goal of modern medicine is the application of personalized therapies, consisting of decisions and practices tailored to the individual patient. Information about genetic variants, either mutant or polymorphic, represents the basis for the development of this clinical approach. Recently, several independent genome-wide association studies (GWAS) have identified two single nucleotide polymorphisms (SNPs) on the IL28B locus associated with HCV containment, spontaneous clearance, treatment response, and disease progression. In this minireview we will concisely discuss some critical genetic concepts that may have possible implications for clinical decisions in the treatment of HCV infection.

Genomics and HCV infection: progression of fibrosis and treatment response

HCV infection is a global health problem that affects 170 million people worldwide. The severity of the disease varies from asymptomatic chronic infection to cirrhosis and hepatocellular carcinoma (HCC). Recently, the standard of care for genotype 1 patients has greatly improved with the addition of protease inhibitors (telaprevir or boceprevir) to pegylated interferon (PegIFN) and ribavirin (RBV). The prediction of fibrosis progression and the response to antiviral treatment are two major issues in the management of patients with chronic hepatitis C. Differential expression of mRNAs was first analyzed for both progression of fibrosis and treatment response. Specific polymorphisms, associated with either fibrosis or viral response, were identified thanks to major improvements in genome scanning technologies. Since 2009, several independent genome wide association studies (GWAS) have reported an association between genetic polymorphisms within the IL-28B promoter and both natural and treatment-induced clearance in genotype 1 infected patients. These different studies showed the strong association and the importance of IL-28B polymorphisms in the treatment response. Combining the different genetic factors could improve their predictive value and help identify patients at a high risk of progression of fibrosis as well as those with a lower chance of responding to treatment. The aim of this review was to discuss the genomic factors (mRNAs, miRNAs, and SNPs) and HCV infection with clinical implications for either progression of fibrosis or treatment response. Recent findings on the IL-28B polymorphism and its application in clinical practice will also be discussed.

Retinoic acid inducible gene-I (RIG-I) signaling of hepatic stellate cells inhibits hepatitis C virus replication in hepatocytes

Retinoic acid inducible gene-I (RIG-I) is critical in the activation of the type I IFN-dependent antiviral innate immune response to hepatitis C virus (HCV) infection. We examined whether hepatic stellate cells (HSC; LX-2) possess a functional RIG-I signaling pathway and produce antiviral factors that can inhibit HCV. We showed that LX-2 cells treated with the RIG-I ligand (5'ppp-dsRNA) expressed significantly higher levels of IFN-β and IFN-λ than the control cells. The RIG-I activation in LX-2 cells also induced the expression of Toll-like receptor 3 (TLR3) and IFN regulatory factor-7 (IRF-7), the key regulators of the IFN signaling pathway. When HCV Japanese fulminant hepatitis (JFH)-1-infected hepatocytes were co-cultured with LX-2 cells stimulated with 5'ppp-dsRNA or incubated in media conditioned with supernatant (SN) from 5'ppp-dsRNA-stimulated LX-2 cells, HCV replication in hepatocytes was suppressed significantly. This LX-2 cell action on HCV replication was mediated through both IFN-β and IFN-λ, as Abs to IFN-α/β or IFN-λ receptors could neutralize the LX-2 SN-mediated anti-HCV effect. The role of IFNs in LX-2 cell-mediated anti-HCV activity is further supported by the observation that LX-2 SN treatment induced the expression of IFN stimulated genes, 2'-5'-oligoadenylate synthase-1 (OAS-1) and myxovirus resistance A (MxA), in HCV-infected Huh7 cells. These observations highlight the importance of HSC in liver innate immunity against HCV infection via a RIG-I-mediated signaling pathway.

Spontaneous clearance of hepatitis C infection after liver transplantation from IL28B rs12979860 CC donors

Genetic polymorphisms adjacent to IL28B have been previously associated with spontaneous clearance of hepatitis C virus (HCV) and a higher rate of sustained virological response to interferon-based treatment in HCV genotype 1-infected patients. A recent study has shown that patients with the CC genotype of the rs12979860 single nucleotide polymorphism upstream from the IL28B gene are more likely to clear HCV spontaneously relative to the CT or TT genotype. In the liver transplant cohort, HCV recurs almost universally in patients with detectable HCV RNA at the time of transplantation. The spontaneous clearance of HCV infection after transplant is very rare. We report two cases of spontaneous clearance of HCV genotype 1 infection after liver transplantation from homozygous IL28B CC donors. This finding may be explained by alterations in the host immune responses to HCV after transplantation with a CC donor liver, which has potential implications for donor selection in HCV-positive recipients.

Measurement and clinical significance of interleukin 28B in hepatitis C virus-infected liver transplant patients

One-third of the liver transplantations are performed because of hepatitis C cirrhosis all over the world and also in Hungary. The recurrence rate is practically 100%, influencing graft and patient survivals; within 5 years cirrhosis develops again in 20% to 30% of cases. The therapy is pegylated interferon α-2a and α-2b plus ribavirin as for nontransplanted subjects with the goal to eradicate the virus and maintain graft function. In 25% to 45% of treated patients, it is possible to achieve a sustained virological response (SVR). The response is influenced by viral, donor, and recipient factors. We investigated the genotype of 68 liver recipients transplanted because of hepatitis C virus (HCV) infection between September 1998 and February 2011. We focused on the interleukin (IL) 28B gene locus single nucleotide polymorphism found on chromosome 19; the rs12979860 minor allele (homozygous [wild TT and CC], heterozygous [CT]) in relation to the interferon response. Ten percent of the patients belonged to the CC, 62% to the CT, and 28% to the TT group, and 83% of the CC group became negative or therapy is still ongoing. The CT genotype reached 15.4% SVR with ongoing treatment for most patients. In TT carriers showed a 23.5% SVR. Our patients formed a homogenous group regarding the surgical team, the therapy, and the HCV genotype. Ninety percent belonged to the possible "hard to treat" group. The 10% CC group gave the highest number of SVR and HCV polymerase chain reaction negativity upon antiviral therapy. Regarding our results, one has to take in consideration the small patient number and the fact that the cirrhotic patients were listed for transplantation where they could not be treated or became therapy-resistant. IL28B is just one predictive factor among others for successful posttransplant HCV therapy; further examinations are needed to fully understand its role.

The impact of interferon lambda 3 gene polymorphism on natural course and treatment of hepatitis C

Host genetic factors may predict the outcome and treatment response in hepatitis C virus (HCV) infection. Very recently, three landmark genome-wide association studies identified single nucleotide polymorphisms near the interleukin 28B (IL28B) region which were more frequent in responders to treatment. IL28B encodes interferon (IFN)λ3, a type III IFN involved in host antiviral immunity. Favourable variants of the two most widely studied IL28B polymorphisms, rs12979860 and rs8099917, are strong pretreatment predictors of early viral clearance and sustained viral response in patients with genotype 1 HCV infection. Further investigations have implicated IL28B in the development of chronic HCV infection versus spontaneous resolution of acute infection and suggest that IL28B may be a key factor involved in host immunity against HCV. This paper presents an overview about the biological activity and clinical applications of IL28B, summarizing the available data on its impact on HCV infection. Moreover, the potential usefulness of IFNλ in the treatment and natural history of this disease is also discussed.

STAT proteins - key regulators of anti-viral responses, inflammation, and tumorigenesis in the liver

Since its discovery in the early 1990s, the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway has been found to play key roles in regulating many key cellular processes such as survival, proliferation, and differentiation. There are seven known mammalian STAT family members: STAT1, 2, 3, 4, 5a, 5b, and 6. In the liver, activation of these STAT proteins is critical for anti-viral defense against hepatitis viral infection and for controlling injury, repair, inflammation, and tumorigenesis. The identification of functions for these STAT proteins has increased our understanding of liver disease pathophysiology and treatments, while also suggesting new therapeutic modalities for managing liver disease.

Hepatitis C virus NS5A disrupts STAT1 phosphorylation and suppresses type I interferon signaling

Responses to alpha interferon (IFN-α)-based treatment are dependent on both host and viral factors and vary markedly among patients infected with different hepatitis C virus (HCV) genotypes (GTs). Patients infected with GT3 viruses consistently respond better to IFN treatment than do patients infected with GT1 viruses. The mechanisms underlying this difference are not well understood. In this study, we sought to determine the effects of HCV NS5A proteins from different genotypes on IFN signaling. We found that the overexpression of either GT1 or GT3 NS5A proteins significantly inhibited IFN-induced IFN-stimulated response element (ISRE) signaling, phosphorylated STAT1 (P-STAT1) levels, and IFN-stimulated gene (ISG) expression compared to controls. GT1 NS5A protein expression exhibited stronger inhibitory effects on IFN signaling than did GT3 NS5A protein expression. Furthermore, GT1 NS5A bound to STAT1 with a higher affinity than did GT3 NS5A. Domain mapping revealed that the C-terminal region of NS5A conferred these inhibitory effects on IFN signaling. The overexpression of HCV NS5A increased HCV replication levels in JFH1-infected cells through the further reduction of levels of P-STAT1, ISRE signaling, and downstream ISG responses. We demonstrated that the overexpression of GT1 NS5A proteins resulted in less IFN responsiveness than did the expression of GT3 NS5A proteins through stronger binding to STAT1. We confirmed that GT1 NS5A proteins exerted stronger IFN signaling inhibition than did GT3 NS5A proteins in an infectious recombinant JFH1 virus. The potent antiviral NS5A inhibitor BMS-790052 did not block NS5A-mediated IFN signaling suppression in an overexpression model, suggesting that NS5A's contributions to replication are independent of its subversive action on IFN. We propose a model in which the binding of the C-terminal region of NS5A to STAT1 leads to decreased levels of P-STAT1, ISRE signaling, and ISG transcription and, ultimately, to preferential GT1 resistance to IFN treatment.

Combined effects of different interleukin-28B gene variants on the outcome of dual combination therapy in chronic hepatitis C virus type 1 infection

In patients with chronic hepatitis C virus (HCV) infection, several variants of the interleukin-28B (IL28B) gene have been shown to correlate significantly with a sustained virologic response (SVR). Recent evidence shows that determination of one single IL28B polymorphism, rs12979860, is sufficient for predicting treatment outcome. We examined whether the combined determination of the IL28B single-nucleotide polymorphisms (SNPs), rs12979860, rs8099917, rs12980275, and rs8103142, might improve the prediction of SVR in patients with HCV. In the study cohort, 54% of 942 patients with chronic HCV type 1 infection had SVR. The IL28B SNPs, rs12979860CC and rs8099917TT, correlated significantly with SVR (68% and 62%). The SNPs, rs12980275 and rs8103142, were in strong linkage disequilibrium with rs12979860 and were not included in further analysis. In homozygous carriers of the rs12979860 responder allele C, additional genotyping of the rs8099917 SNP had no effect on response prediction, whereas in carriers of the rs12979860 nonresponder allele, the rs8099917 SNP improved the response prediction. In heterozygous carriers of the rs12979860 nonresponder T allele, SVR rates were 55% in the presence of the rs8099917TT genotype and 40% in patients carrying the rs8099917 TG or GG genotype. Analysis of an independent confirmation cohort of 377 HCV type 1-infected patients verified the significant difference in SVR rates between the combined genotypes, rs12979860CT/rs8099917TT and rs12979860CT/rs8099917TG (38% versus 21%; P = 0.018).

CONCLUSION

Treatment outcome prediction could not be improved in homozygous carriers of the IL28B rs12979860 C responder allele by the additional determination of the rs8099917 SNP. There is evidence that a significant proportion of heterozygous carriers of the rs12979860 T nonresponder allele can profit with respect to SVR prediction by further determination of the rs8099917 SNP. (HEPATOLOGY 2012;55:1700-1710).

Genetics of IL28B and HCV--response to infection and treatment

The IL28B locus attracted the attention of HCV researchers after a series of genome-wide association studies independently identified a strong association between common IL28B polymorphisms and the outcome of PEG-IFN-α plus ribavirin combination therapy in patients chronically infected with HCV genotype 1. This association was subsequently replicated for other HCV genotypes and has been linked to spontaneous eradication of HCV, development of steatosis and biochemical changes (such as altered levels of γ-glutamyl transpeptidase and LDL). Despite the introduction of direct-acting antiviral drugs, IL28B genetics are likely to play a part in patient selection and treatment decisions-moving towards a personalized approach to therapy. In HCV-infected patients with the so-called favourable IL28B genotype (rs12979860 CC; associated with better treatment response), hepatic expression levels of IL28B and interferon-stimulated genes seem to be reduced at baseline, but are induced more strongly after IFN-α administration, perhaps resulting in more effective elimination of the virus. Clarification of the mechanisms underlying these biological phenomena will lead to improved understanding of the antiviral effects of IFN-λ and, ideally, to the development of better therapies against HCV infection. This Review summarizes current understanding of the role of IL28B in HCV infection and response to therapy.

LDLr genotype modifies the impact of IL28B on HCV viral kinetics after the first weeks of treatment with PEG-IFN/RBV in HIV/HCV patients

OBJECTIVE

To evaluate the effect of low-density lipoprotein receptor (LDLr) and IL28B genotypes on hepatitis C virus (HCV) viral kinetics in the first 4 weeks of treatment with pegylated-interferon (PEG-IFN)/ribavirin (RBV) in HIV patients co-infected with HCV genotype 1.

METHODS

HIV patients co-infected with HCV genotype 1 and naïve to PEG-IFN/RBV treatment were enrolled in a prospective study. HCV RNA viral loads were measured at baseline and at weeks 1, 2 and 4 after start of therapy. Differences in viral load decline were evaluated for IL28B (CC versus non-CC) and LDLr (CC versus non-CC) genotypes between baseline and weeks 1, 2 and 4. Additionally, the effect of LDLr genotype on HCV viral decline in IL28B CC genotype patients (CC/CC versus CC/non-CC) was analyzed.

RESULTS

Eighty-seven HIV/HCV genotype 1 co-infected patients were included in the study. Patients carrying the LDLr-CC or IL28B-CC genotypes showed greater HCV viral decline than those with IL28B non-CC or LDLr non-CC genotypes at every time-point analyzed. CC/CC patients had higher rapid virological response (RVR) rates than CC/non-CC patients (41.2 versus 13.3%; P < 0.001). Moreover, at all time points, the CC/CC pattern was associated with greater HCV viral decline than the CC/non-CC genotype (week 1: 1.18 ± 0.51 versus 0.31 ± 0.29, P = 0.041; week 2: 1.55 ± 0.81 versus 0.93 ± 0.73, P = 0.032; week 4: 2.23 ± 1.1 versus 1.5 ± 0.94, P = 0.039).

CONCLUSION

The LDLr genotype impacts on viral kinetics during the first days of starting treatment with PEG-IFN/RBV in HIV/HCV genotype 1 co-infected patients, and modifies the impact of IL28B on HCV viral decay.

Anti-hepatitis C virus drugs in development

Development of robust cell culture models for hepatitis C viral infection has greatly increased our understanding of this virus and its life cycle. This knowledge has led to the development of many drugs that target specific elements of viral replication, including viral proteins and host factors required for replication. The NS3/4A serine protease inhibitors were the first of these to be used in the clinic, and reagents that target other elements of the viral lifecycle are in advanced stages of clinical development. These include new NS3/4A protease inhibitors, NS5B RNA-dependent RNA polymerase inhibitors, NS5A inhibitors, and host-directed antivirals, such as cyclophilin inhibitors. Alternative interferons with possibly improved tolerability, specifically interferon-λ1 (interleukin-29), are also under development. These new reagents against hepatitis C virus should lead to highly effective, well-tolerated, and likely interferon-sparing therapies in the next several years.

Anti-hepatitis C virus activity of 3-hydroxy caruilignan C from Swietenia macrophylla stems

Chronic hepatitis C virus (HCV) infection ultimately leads to chronic hepatitis, hepatic cirrhosis and hepatocellular carcinoma (HCC). As the standard treatment is not completely efficacious, a safer and more effective agent against HCV infection needs to be developed. In this report, we demonstrated that 3-hydroxy caruilignan C (3-HCL-C) isolated from Swietenia macrophylla stems exhibited high anti-HCV activity at both protein and RNA levels at nontoxic concentrations, with an EC(50) value of 10.5 ± 1.2 μm. Combinations of 3-HCL-C and interferon-α (IFN-α), an HCV NS5B polymerase inhibitor (2'-C-methylcytidine; NM-107) or an HCV NS3/4A protease inhibitor (Telaprevir; VX-950) increased the suppression of HCV RNA replication. The results suggested that 3-HCL-C may be a potential anti-viral agent. We then demonstrated that 3-HCL-C interfered with HCV replication by inducing IFN-stimulated response element transcription and IFN-dependent anti-viral gene expression.

IFN-λ3 inhibits HIV infection of macrophages through the JAK-STAT pathway

BACKGROUND

Interferon lambda 3 (IFN-λ3) is a newly identified cytokine with antiviral activity, and its single nucleotide polymorphisms are strongly associated with the treatment effectiveness and development of chronic hepatitis C virus infection. We thus examined the potential of IFN-λ3 to inhibit HIV replication and the possible mechanisms of the anti-HIV action by IFN-λ3 in human macrophages.

PRINCIPAL FINDINGS

Under different conditions (before, during, and after HIV infection), IFN-λ3 significantly inhibited viral replication in macrophages, which was associated with the induction of multiple antiviral cellular factors (ISG56, MxA, OAS-1, A3G/F and tetherin) and IFN regulatory factors (IRF-1, 3, 5, 7 and 9). This anti-HIV action of IFN-λ3 could be compromised by the JAK-STAT inhibitor. In addition, IFN-λ3 treatment of macrophages induced the expression of toll-like receptor 3 (TLR3) and two key adaptors (MyD88 and TRIF) in type I IFN pathway activation. However, HIV infection compromised IFN-λ3-mediated induction of the key elements in JAK-STAT signaling pathway.

CONCLUSIONS

These data indicate that IFN-λ3 exerts its anti-HIV function by activating JAK-STAT pathway-mediated innate immunity in macrophages. Future in vivo studies are necessary in order to explore the potential for developing IFN-λ3-based therapy for HIV disease.