Influence of genes suppressing interferon effects in peripheral blood mononuclear cells during triple antiviral therapy for chronic hepatitis C

Role of SOCS1 Gene in Chronic Hepatitis C Virus Patients: A Mini-Review

Hepatitis C virus (HCV) is a global health problem, with an estimated bioburden of >180 million. Every year about 350,000 people die from HCV-associated liver complications such as cirrhosis and cancer (e.g., hepatocellular carcinoma). Pakistan has the second highest prevalence of HCV. Treatment of this life-threatening disease has been a challenge, but recent developments in direct-acting antivirals have offered hope to many. Although direct-acting antivirals have dramatically improved viral clearance, their exorbitant costs put them out of reach for patients in developing countries. Thus, interferon therapy is still being used in Pakistan. Specifically, interferon-stimulating genes can alter treatment response. For example, interferons induce expression of many antiviral genes through signal transducer and activator of transcription/Janus kinase signaling. Suppressor of cytokine signaling genes play an eminent role in the inhibition of cytokine signaling pathways and regulation of both adaptive and innate immunity. The present review examines expression of suppressor of cytokine signaling-1 in HCV-treated patients.

Dynamic changes in innate immune responses during direct-acting antiviral therapy for HCV infection

The role of the endogenous interferon (IFN) system has been well characterized during IFN-based therapy for chronic hepatitis C virus (HCV) infection; less is known for direct-acting antivirals (DAAs). In this phase 3b open-label study, we assessed changes in IFN-stimulated genes (ISGs) in non-cirrhotic treatment-naïve or pegIFN/RBV-experienced HCV-GT1a-infected patients receiving paritaprevir/ritonavir/ombitasvir + dasabuvir + ribavirin (PrOD + R) for 12 weeks. ISG expression was quantified from peripheral blood mononuclear cells at baseline, treatment weeks (TW)2, TW4, TW8, end of treatment (EOT) and at post-treatment week 12. Paired sera were used to assess IFN-α/IFN-related chemokines/cytokines. Twenty-five patients were enrolled. Overall sustained virologic response (SVR)12 was 92% (no virologic failure [VF]) and 100% for those completing the study protocol. Two patients were excluded from the ISG analysis due to lack of post-treatment samples. The majority of ISGs were downregulated at TW2-TW4 (nadir TW4); however, a relative increase was observed at TW8-EOT, although levels were lower than baseline. This downregulation was accompanied by increases in IFN-α/IFN-related chemokines, a finding not observed with T_H 1/2-related cytokines. Following SVR, ISG expression returned to TW2 levels. In conclusion, PrOD + R for 12 weeks was well-tolerated with no VF. Our data demonstrate dynamic alterations in innate immune profiles during highly potent IFN-free DAA therapy. The downregulation of ISG post-therapy suggests reversal of the "exhausted" ISG phenotype following SVR, and the rise in ISGs and IFN-α/IFN-responsive chemokines late during therapy suggests resetting of IFN responsiveness that may be relevant in determining duration of or immunological sequelae from DAA therapy, including HBV reactivation.

Hepatic IFNL4 expression is associated with non-response to interferon-based therapy through the regulation of basal interferon-stimulated gene expression in chronic hepatitis C patients

Single nucleotide polymorphisms (SNPs) within or near interferon lambda 4 (IFNL4) gene located upstream of IFNL3 are associated with response to anti-HCV therapy both in interferon (IFN)-based and IFN-free regimens. IFNL4 encodes IFNλ4, a newly discovered type III IFN, and its expression is controlled by rs368234815-TT/ΔG, which is in strong linkage disequilibrium (LD) with other tag SNPs within or near IFNL4 such as rs12979860 and rs8099917. Intrahepatic expression levels of IFN-stimulated genes (ISGs) affect the responsiveness to IFNα and are also associated with IFNL4 genotype. However, IFNL4 expressions and its role in intrinsic antiviral innate immunity remain unclear. This study evaluated the effect of IFNL4 on intrahepatic ISG expression and investigated its relationship with treatment outcomes in liver samples obtained from 49 chronic hepatitis C patients treated with pegylated (PEG)-IFN/ribavirin therapy. IFNL4 mRNA was detected in 11 of 22 patients with IFNL4-unfavorable SNPs but not in patients with favorable genotypes. IFNL4 expression was associated with non-response to PEG-IFN/ribavirin therapy. Intrahepatic expression of antiviral ISGs (ISG15 and MX1) was significantly higher in IFNL4-unfavorable patients with detectable IFNL4 mRNA than in patients with undetectable IFNL4 mRNA, whereas the expression of suppressive ISGs (RNF125, SOCS1, SOCS3, and RNF11) was lower in patients with detectable IFNL4 mRNA. In summary, intrahepatic expression of IFNL4 was associated with increased antiviral ISG expression and decreased suppressive ISG expression at baseline, resulting in poor responsiveness to IFNα-based therapy in HCV infection.

Association between IL28B rs12979860 single nucleotide polymorphism and the frequency of colonic Treg in chronically HCV-infected patients

The IL28B gene is associated with spontaneous or treatment-induced HCV viral clearance. However, the mechanism by which the IL28B single nucleotide polymorphism (SNP) affects the extra-hepatic HCV immune responses and its relationship to HCV pathogenesis have not been thoroughly investigated. To examine the mechanism by which IL28B affects HCV clearance. Forty Egyptian patients with chronic HCV infection receiving an Interferon/ribavirin treatment regimen were enrolled into this study. There were two groups: non-responders (NR; n = 20) and sustained virologic responders (SVR; n = 20). The initial plasma HCV viral loads prior to treatment and IL28B genotypes were determined by quantitative RT-PCR and sequencing, respectively. Liver biopsies were examined to determine the inflammatory score and the stage of fibrosis. Colonic regulatory T cell (Treg) frequency was estimated by immunohistochemistry. No significant association between IL28B genotypes and response to therapy was identified, despite an odds ratio of 3.4 to have the TT genotype in NR compared to SVR (95 % confidence interval 0.3-35.3, p = 0.3). Patients with the TT-IL28Brs12979860 genotype (unfavorable genotype) have significantly higher frequencies of colonic Treg compared to the CT (p = 0.04) and CC (p = 0.03) genotypes. The frequency of colonic Treg cells in HCV-infected patients had a strong association with the IL-28B genotype and may have a significant impact on HCV clearance.

IFN-stimulated gene expression is independent of the IFNL4 genotype in chronic HIV-1 infection

This study aimed to evaluate the association between the IFNL4 rs368234815 (ΔG/TT) dinucleotide polymorphism and the IFN response during chronic HIV-1 infection. We carried out genotyping analysis and measured the expression of IFN-stimulated genes (ISGs) (myxovirus resistance protein A [MxA], ISG15, ISG56, apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like [APOBEC] 3F and APOBEC3G) on peripheral blood mononuclear cells collected from naïve and HAART-treated HIV-1-infected patients. There were no statistically significant differences in endogenous ISGs mRNA levels among HIV-1-positive patients bearing different IFNL4 genotypes, suggesting that ISG expression is independent of the IFNL4 genotype in HIV-1 infection.

Suppressor of cytokine signaling 1 expression in peripheral blood mononuclear cells of hepatitis C genotype 1 patients

BACKGROUND/PURPOSE

While new direct-acting antiviral therapies for hepatitis C virus (HCV) are the standard of care, interferon-α (IFN-α) remains a standard therapy in Taiwan based on its low cost and high response rate to IFN-α-based therapy. IFN-α exerts antiviral activity by inducing the expression of hundreds of genes that establish an antiviral state via Jak kinase (JAK)/signal transducers and activators of transcription (STAT) signaling. We quantified the transcript levels of JAK/STAT signaling genes in peripheral blood mononuclear cells of HCV genotype 1 patients and estimated the correlation between transcript levels and patient responses to IFN-α-based therapy.

METHODS

A total of 100 HCV genotype 1 naïve patients were enrolled. All patients received response-guided therapy for 24-48 weeks with pegylated IFN-α and ribavirin. Peripheral blood mononuclear cells were collected before treatment. Twenty patients with sustained virological responses (SVR) and 20 patients without SVR were selected for a JAK/STAT signaling genes transcript analysis using multiplex reverse transcription-polymerase chain reaction. Transcripts that were upregulated or downregulated were further validated in 100 patients.

RESULTS

Suppressor of cytokine signaling 1 (SOCS1) expression was upregulated in SVR patients compared with non-SVR patients (relative quantification = 2.14) based on a multiplex reverse transcription-polymerase chain reaction analysis. We further analyzed SOCS1 expression in 100 patients. We found that SOCS1 expression did not differ significantly between SVR and non-SVR patients.

CONCLUSION

Peripheral blood SOCS1 expression before treatment was not associated with SVR in HCV genotype 1 patients treated with pegylated IFN-α and ribavirin.

Type III Interferon Induces Distinct SOCS1 Expression Pattern that Contributes to Delayed but Prolonged Activation of Jak/STAT Signaling Pathway: Implications for Treatment Non-Response in HCV Patients

Suppressor of cytokine signaling 1 (SOCS1) has long been thought to block type I interferon signaling. However, IFN-λ, a type III IFN with limited receptor expression in hepatic cells, efficiently inhibits HCV (Hepatitis C virus) replication in vivo with potentially less side effects than IFN-α. Previous studies demonstrated that type I and type III activated Janus kinase/signal transducer and activator of transcription (Jak/STAT) signaling pathway differently, with delayed but prolonged activation by IFN-λ stimulation compared to IFNα/β. However, the molecular mechanisms underlying this observation is not well understood. Here, we found that there are distinct differences in SOCS1 expression patterns in Huh-7.5.1 cells following stimulation with IFN-α and IFN-λ. IFN-λ induced a faster but shorter expression of SOCS1. Furthermore, we confirmed that SOCS1 over-expression abrogates anti-HCV effect of both IFN-α and IFN-λ, leading to increased HCV RNA replication in both HCV replicon cells and JFH1 HCV culture system. In line with this, SOCS1 over-expression inhibited STAT1 phosphorylation, attenuated IFN-stimulated response elements (ISRE) reporter activity, and blocked IFN-stimulated genes (ISGs) expression. Finally, we measured SOCS1 mRNA expression levels in peripheral blood mononuclear cells (PBMCs) with or without IFN-α treatment from 48 chronic hepatitis C patients and we found the baseline SOCS1 expression levels are higher in treatment non-responders than in responders before IFN-α treatment. Taken together, SOCS1 acts as a suppressor for both type I and type III IFNs and is negatively associated with sustained virological response (SVR) to IFN-based therapy in patients with HCV. More importantly, faster but shorter induction of SOCS1 by IFN-λ may contribute to delayed but prolonged activation of IFN signaling and ISG expression kinetics by type III IFN.