Interferon signaling and treatment outcome in chronic hepatitis C

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease worldwide. The current standard therapy for chronic hepatitis C (CHC) consists of a combination of pegylated IFN alpha (pegIFNalpha) and ribavirin. It achieves a sustained viral clearance in only 50-60% of patients. To learn more about molecular mechanisms underlying treatment failure, we investigated IFN-induced signaling in paired liver biopsies collected from CHC patients before and after administration of pegIFNalpha. In patients with a rapid virological response to treatment, pegIFNalpha induced a strong up-regulation of IFN-stimulated genes (ISGs). As shown previously, nonresponders had high expression levels of ISGs before therapy. Analysis of posttreatment biopsies of these patients revealed that pegIFNalpha did not induce expression of ISGs above the pretreatment levels. In accordance with ISG expression data, phosphorylation, DNA binding, and nuclear localization of STAT1 indicated that the IFN signaling pathway in nonresponsive patients is preactivated and refractory to further stimulation. Some features characteristic of nonresponders were more accentuated in patients infected with HCV genotypes 1 and 4 compared with genotypes 2 and 3, providing a possible explanation for the poor response of the former group to therapy. Taken together with previous findings, our data support the concept that activation of the endogenous IFN system in CHC not only is ineffective in clearing the infection but also may impede the response to therapy, most likely by inducing a refractory state of the IFN signaling pathway.     

Hepatitis C virus kinetics during the first phase of pegylated interferon-α-2b with ribavirin therapy in patients with living donor liver transplantation

Aim:  To identify the problems of pegylated interferon (PEG IFN) with ribavirin therapy against hepatitis C virus (HCV) reinfection in living donor liver transplantation (LDLT) patients. HCV kinetics during the PEG IFN with ribavirin therapy were analyzed in LDLT patients, as well as in chronic hepatitis C (CHC) patients.
Methods:  The study included 80 consecutive HCV infected patients undergoing PEG IFN with ribavirin therapy (64 CHC and 16 LDLT patients) who attended the Nagasaki University Hospital for an initial visit between January 2005 and December 2007.
Results:  The sustained viral response (VR) rate of the CHC group (80%) was superior to the LDLT group (22%). The viral disappearance rate of the CHC group was also superior to the LDLT group, regardless of the HCV serotype. The HCV core antigen (cAg) titer under treatment in the LDLT group was more than that of the CHC group from day 0 to week 12. The HCV cAg decrease rate of the LDLT group on the first day of treatment was less than that of the CHC group.
Conclusion:  The HCV infection of a transplanted liver is more refractory to treatment than a non-transplanted liver. The low reduction HCV cAg rate on day 1 is one of the problems of the combination therapy.     

慢性丙型肝炎患者肝组织中病毒和Fas抗原表达及其与干扰素应答的关系

目的 探讨丙型肝炎患者肝组织中HCV Ns5和Fas抗原表达及其与肝组织损伤和干扰素治疗反应的关系.方法 应用a干扰素对一组慢性丙型肝炎患者进行24周治疗,停药后随访6个月,以血清丙氨酸转氨酶(ALT)恢复正常及血清HCV RNA持续阴转为完全应答标准,采用免疫组化方法检测组织中病毒和Fas抗原表达状况.结果 29例慢性丙型肝炎患者肝组织中,HCV NS5和Fas抗原呈阳性者均为19例(65.5%),两者在肝组织中的表达显著相关;单因素相关分析时,两者均与组织病变程度有关,但多因素分析表明只有HCV NS5抗原表达水平与组织炎症活动度呈正相关.治疗和随访结束时分别有17例(58.6%)和15例(51.7%)患者表现为近期和远期完全应答.治疗前Fas表达水平与干扰素应答有关,但未见HCV NS5水平与干扰素应答有明显关系;5例随访结束时重复肝穿,3例完全应答者病毒表达显著受抑,但Fas抗原无明显改变,2例无应答者病毒表达无明显改变甚或增强,而Fas表达均增强.结论 慢性丙型肝炎肝组织中HCV Ns5表达在慢性丙型肝炎发病过程中有重要意义;Fas抗原表达水平与组织中病毒表达相关;治疗前肝组织Fas表达状况与干扰素治疗反应有一定联系.     

Response to interferon in chronic hepatitis C due to mixed genotype infection

We examined the response to interferon (IFN) in patients with chronic hepatitis C (CHC) due to two different genotypes of hepatitis C virus (HCV) infection. Among 64 CHC patients studied, one (2%) had HCV-RNA genotype I, 36 (56%) had genotype II, 19 (30%) had genotype III, 2 (3%) had genotype IV and 6 (9%) had both genotypes II and III. There was no significant difference in age, sex, history of blood transfusion and liver histology among patients with genotypes II, III and II + III. The HCV-RNA titre of genotype II patients was significantly higher than that of genotype III patients (P < 0.05). However, there was no significant difference in the HCV-RNA titre between genotype II + III and the other groups. The complete response rate achieved with IFN therapy was significantly higher in genotype III patients (74%) than in genotype II patients (17%; P < 0.01). Of the six patients with genotype II + III, a complete response to IFN was only achieved by two patients (33%), both of whom had a low HCV-RNA titre (≦ 10^4,5 copies/mL) and HCV serotype 2. The remaining four patients had HCV serotype 1 and three of the patients had a high HCV-RNA titre (≧ 10⁵ copies/mL). The HCV genotype III was lost in two patients after IFN therapy. These data suggest that HCV-RNA titre and HCV serotype are important factors for predicting the efficacy of IFN therapy in patients with mixed genotype infection and show direct evidence of higher susceptibility towards CHC of patients with genotype III than genotype II.     

Preactivation of the interferon signalling in liver is correlated with nonresponse to interferon alpha therapy in patients chronically infected with hepatitis B virus

Interferon alpha (IFN-α) therapy is widely used to treat patients with chronic hepatitis B (CHB) but the sustained response rate is low, and the molecular mechanisms for the ineffectiveness of IFN-α treatments are not known. We screened differentially expressed genes between responders (Rs) and nonresponders (NRs) in patients with CHB treated with IFN-α to explore the molecular basis for treatment failure. Expression profiling was performed on percutaneous needle liver biopsy specimens taken before therapy. Gene expression levels were compared between seven patients who did not respond to therapy (NR) and six who did respond (R). Gene ontology category and KEGG pathway were analysed for differentially expressed genes, and the selected differentially expressed genes were confirmed using real-time polymerase chain reaction. We identified 3592 genes whose expression levels differed significantly between all Rs and NRs (P < 0.05); many of these genes are IFN-stimulated genes (ISGs) and immune-related genes. The ISGs were more highly expressed, while immune-related genes were inhibited in NRs before IFN-α treatment. Two ISGs (CEB1 and USP18) that are linked in an IFN inhibitory pathway are highly expressed in NRs, and a potential antiviral gene ISG20 was inhibited in NRs, suggesting a possible rationale for treatment nonresponse. Patients who do or do not respond to IFN have different liver gene expression profiles before IFN-α treatment. Preactivation of the IFN signalling pathway leading to the increased expression of inhibitory ISGs and inhibition of immune response in the pretreatment livers was associated with treatment failure.     

Defective hepatic response to interferon and activation of suppressor of cytokine signaling 3 in chronic hepatitis C

BACKGROUND & AIMS: Approximately half of hepatitis C virus (HCV)-infected patients do not respond to current interferon (IFN)-alpha combination therapy. To understand IFN-alpha resistance in vivo, we examined the dynamic responses to both type I and type II IFNs, human IFN (hIFN)-alpha, -gamma, and consensus IFN, in the chimpanzee model. METHODS: Naive and HCV-infected chimpanzees were treated with 3 forms of hIFNs in vivo. Quantitative real-time polymerase chain reaction was performed to evaluate the expression of IFN-stimulated genes (ISGs) in both peripheral blood mononuclear cells and liver to compare the responses to hIFN between naive and infected chimpanzees. The hepatic expression of IFN signaling components and inhibitory regulators including suppressor of cytokine signaling 3 (SOCS3) were assessed. SOCS3 expression was also evaluated in the liver of HCV-infected patients undergoing IFN treatment. RESULTS: The in vivo responses to all 3 hIFNs were much lower in the HCV-infected chimpanzees than those in the naive chimpanzees. This defect was particularly evident in the liver because induction of hepatic ISGs was barely detectable in the infected animals. Following IFN administration, the expression of SOCS3 was significantly up-regulated, possibly through induction of interleukin-6, in the liver of HCV-infected chimpanzees. HCV-infected humans also showed a differential pattern of hepatic SOCS3 expression in response to IFN that is associated with treatment response. CONCLUSIONS: Our data indicate a predominantly defective hepatic response to IFN in HCV-infected chimpanzees, which is probably mediated through the activation of SOCS3 and may explain the nonresponse of many HCV patients to IFN-based therapy.     

Clinical trial results of peginterferons in combination with ribavirin

Of the large number of patients chronically infected with hepatitis C virus (HCV), only about one third have progressive liver disease, and will eventually develop cirrhosis and hepatocellular carcinoma. These are the patients for whom effective antiviral treatment is most needed. Therapy is currently recommended for patients with chronic hepatitis C who have abnormal alanine aminotransferase (ALT) levels, detectable hepatitis C virus ribonucleic acid (HCV RNA) in the blood, and significant necroinflammatory changes and/or fibrosis on liver biopsy. The current gold standard in terms of treatment efficacy is the combination of peginterferon (PEG-IFN) and ribavirin. The overall sustained virological response rate (SVR) with these regimens is 54 to 61% following 48 weeks of therapy. Patients with genotype 1 infection have a 42 to 51% likelihood of response to 48 weeks of therapy. Those with genotypes 2 or 3 infection will respond to 24 weeks of therapy in 78 to 82% of cases. These SVR rates are 5 to 10 percentage points higher in all patient groups than in those obtained with standard doses of interferon (IFN) and ribavirin. Retreatment of nonresponders to standard IFN monotherapy using PEG-IFN and ribavirin has achieved SVR rates of 34 to 40%. Retreatment of patients who relapsed after IFN monotherapy has resulted in an SVR rate of about 60%. A SVR after retreatment of relapsers and nonresponders with PEG-IFN and ribavirin is more likely in patients previously treated with IFN monotherapy, those with HCV genotypes 2 or 3, patients with low viral load (<2 million copies/mL), and individuals who had a significant decrease in HCV RNA levels during the initial treatment. The potential benefits of long-term anti-HCV suppressive therapy in nonresponders are currently under investigation.     

IFN‐free therapy is associated with restoration of type I IFN response in HIV‐1 patients with acute HCV infection who achieve SVR

Interferon (IFN)‐free direct‐acting antiviral agents (DAAs) have revolutionized chronic hepatitis C virus (HCV) treatment; early studies suggest excellent efficacy in acute HCV. However, changes in innate immune responses during DAA therapy for acute HCV are unknown. We studied interferon‐stimulated gene (ISG) expression and related cytokines/chemokines in HIV‐infected patients with acute HCV receiving sofosbuvir plus ribavirin (SOF+RBV) as part of the A5327 clinical trial. ISG expression was determined from PBMCs, and circulating cytokines/chemokines were quantified from serum from study participants. The overall sustained virologic response (SVR) was 57%; all treatment failures were due to virologic relapse. Apart from NOS2a, baseline ISG/chemokine/cytokine levels were similar irrespective of treatment outcome. Downregulation of ISGs was observed at treatment week four and end of treatment (EOT), implicating HCV in establishing elevated ISGs early during HCV infection. Levels of many of these ISGs increased at post‐treatment week 12 (PTW12) in relapsers only, coinciding with recurrent HCV RNA. Eleven ISGs were differentially expressed in responders vs relapsers. On‐treatment viral suppression was also associated with a reduction in IP‐10, CXCL11 and MIP‐1β levels. In contrast, circulating IFN‐α levels were significantly higher at EOT and PTW12 in responders vs relapsers. Upregulation of peripheral ISG expression is established early in the course of HCV infection during acute HCV infection, but did not predict subsequent treatment outcome with SOF+RBV. ISGs were downregulated during therapy and increased post‐therapy in relapsers. IFN‐α levels were higher in responders at EOT/PTW12, suggesting that impaired type I IFN production/secretion may contribute to relapse.     

Histological response to interferon alfa-based therapies in hepatitis C

Histological response is defined as an improvement in the severity of liver inflammation with or without an improvement in fibrosis in patients following treatment for an acute or chronic liver disorder. Histological response occurs in patients with chronic hepatitis C virus (HCV) infection who have had a sustained virological response following treatment with interferon (IFN) therapy and in a percentage of nonresponders. Continuing IFN long term as maintenance therapy has been shown to prevent histological progression in patients who had both a marked decline in serum HCV RNA level during treatment and a histological response on repeat histological analysis. Prospective controlled trials are currently evaluating the benefits of low-dose maintenance therapy with pegylated IFN in HCV patients who have failed to achieve sustained virological response. In the future, the development of serum markers of fibrosis may allow for monitoring of hepatic fibrosis and histological response to therapy without the need to perform repeat liver biopsy.     

不同HCV基因型感染的慢性丙型肝炎和肝硬化患者对重组人干扰素α-2a治疗应答的影响

目的 研究丙型肝炎病毒(HCV)基因型对慢性丙型肝炎(CHC)和丙型肝炎肝硬化患者接受干扰素α-2a治疗的影响。方法 2015年1月～2020年4月我院收治的CHC患者198例和丙型肝炎肝硬化患者200例,均接受肝活检和干扰素α-2a治疗24 周,随访24周。采用实时荧光定量PCR法检测血清HCV RNA水平,采用基因序列测定法检测HCV基因分型,采用单因素和多因素回归分析影响治疗应答的因素。结果 肝硬化组HCV基因1b型检出率为31.0%,显著高于86例≤S1的15.1%或112例S2～3组的18.8%(P<0.05);212例无应答组HCV基因1b型检出率显著高于186例治疗应答组(29.7%对17.7%),1a型检出率显著低于治疗应答组(17.9%对28.0%,P<0.05);应答组早期应答率为60.8%,显著高于无应答组的18.9%(P<0.05),应答组治疗前血清HCV RNA高水平比率为37.1%,显著低于无应答组的47.6%(P<0.05);HCV基因1b型(OR为0.553,95%CI为0.316～0.969)是影响干扰素治疗应答的危险因素,而早期应答(OR为1.704,95%CI为1.008～2.881)为影响干扰素治疗应答的保护因素。结论 HCV基因型可影响干扰素α-2a治疗慢性HCV感染者的应答反应,检测病毒基因型可能对选择合适的治疗方案或疗程有指导意义。     

HCV RNA levels in serum, liver, and peripheral blood mononuclear cells of chronic hepatitis C patients and their relationship to liver injury

Objective: We sought to evaluate the relationship between HCV RNA levels in serum, liver, and peripheral blood mononuclear cells (PBMC) and the degree of liver injury in chronic hepatitis C (CHC) patients.
Methods: Thirty-six consecutive CHC patients were included in the study. The liver damage was evaluated by the histological activity index (HAI) score. The HCV RNA levels in the three compartments studied were assessed by bDNA assay. Nineteen patients were treated with α-interferon 2b (IFN).
Results: Serum and liver HCV RNA levels in CHC patients were significantly associated with an increasing HAI score irrespective of the HCV genotypes. Cirrhotic patients showed higher HCV RNA levels than the CHC patients with HAI score 1–4 (   p < 0.05  ), but had lower levels than the group with HAI score > 8 (   p < 0.03  ). Patients with HAI score 1–4 showed the lowest levels of HCV RNA in PBMC. There was a strong relation (  r = 0.78  ;   p < 0.001  ) between serum and liver HCV RNA levels, but not between either serum or liver HCV RNA levels and those of PBMC. Seven patients showed a response to IFN and three of these had a sustained response. Pretreatment levels of HCV RNA in PBMC of the IFN responder patients were lower than those of the nonresponder patients (   p < 0.02  ).
Conclusions: The data indicate a relation between serum or liver HCV RNA levels and the degree of liver injury in CHC patients, and show that serum HCV RNA level mirrors the hepatic viral burden.     

Combination of interferon and ribavirin in chronic hepatitis C: re-treatment of nonresponders to interferon

Chronic infection with hepatitis C virus (HCV) may result in cirrhosis, liver failure, and hepatocellular carcinoma. A minority of patients have a sustained response to antiviral therapy, and nonresponders remain at risk of developing progressive liver disease. We conducted a randomized, controlled trial of therapy with the combination of interferon (IFN) and ribavirin in patients with chronic hepatitis C who had not responded to an initial course of therapy with IFN alone. A total of 124 patients were randomized to receive the combination of IFN and ribavirin for either 24 or 48 weeks and followed for an additional 24 weeks after stopping therapy. Thirty-eight treated patients (30.6%) achieved a sustained virologic response (undetectable HCV RNA at the 24-week follow-up point). This was associated with significant improvement in necroinflammatory activity noted on liver biopsy. Interestingly, there was not a statistically significant difference in response rates based on the duration of treatment; HCV genotype was the strongest predictor of a sustained response. Sustained responses were noted even in patients with poor predictive factors, including those with advanced hepatic fibrosis or cirrhosis, high levels of HCV RNA in serum, and those infected with HCV genotype 1. The study included 24 patients with normal serum alanine transaminase (ALT) values before therapy who had similar responses to those with initially elevated transaminase values. This study suggests that the combination of IFN and ribavirin is a useful modality of therapy in patients with chronic hepatitis C who did not respond to IFN alone.     

S-Adenosylmethionine and betaine correct hepatitis C virus induced inhibition of interferon signaling in vitro

Hepatitis C virus (HCV) infection is an important cause of chronic liver disease. Standard therapy, pegylated interferon alpha (pegIFNalpha) combined with ribavirin, results in a sustained response rate in approximately half of patients. The cause of treatment failure in the other half of the patients is unknown, but viral interference with IFNalpha signal transduction through the Jak-STAT pathway might be an important factor. We have shown previously that the expression of HCV proteins leads to an impairment of Jak-STAT signaling because of an inhibition of STAT1 methylation. Unmethylated STAT1 is less active because it can be bound and inactivated by its inhibitor, protein inhibitor of activated STAT1 (PIAS1). We show that treating cells with S-adenosyl-L-methionine (AdoMet) and betaine could restore STAT1 methylation and improve IFNalpha signaling. Furthermore, the antiviral effect of IFNalpha in cell culture could be significantly enhanced by the addition of AdoMet and betaine. In conclusion, we propose that the addition of these drugs to the standard therapy of patients with chronic hepatitis C could overcome treatment resistance.     

Virus-induced over-expression of protein phosphatase 2A inhibits insulin signalling in chronic hepatitis C

BACKGROUND/AIMS: Hepatitis C virus (HCV) infection disturbs glucose and lipid metabolism contributing to the development of liver steatosis, insulin resistance and type 2 diabetes mellitus. On the other hand, insulin resistance and steatosis have been found to be associated with increased rates of fibrosis progression and lower rates of response to interferon therapy in chronic hepatitis C (CHC). The molecular mechanisms contributing to insulin resistance in CHC are not well understood. We have shown previously that protein phosphatase 2A (PP2A) is over-expressed in biopsies from patients with CHC. In this study, we tested if PP2A over-expression leads to insulin resistance. METHODS: We studied insulin signalling in cell lines that allow the regulated over-expression of HCV proteins and of the PP2A catalytic subunit (PP2Ac). Insulin signalling and PP2Ac expression were also studied in HCV transgenic mice and in liver biopsies from patients with CHC. RESULTS: Over-expression of PP2Ac in cells inhibited insulin signalling by dephosphorylation of PKB/Akt. PP2Ac over-expression and impaired insulin signalling were found in the liver of HCV transgenic mice and in liver biopsies of patients with CHC. CONCLUSIONS: HCV-induced over-expression of PP2A in the liver contributes to the pathogenesis of insulin resistance in patients with CHC.     

Hepatitis C virus induces interferon-λ and interferon-stimulated genes in primary liver cultures

Hepatitis C virus (HCV) replication in primary liver cells is less robust than that in hepatoma cell lines, suggesting that innate antiviral mechanisms in primary cells may limit HCV replication or spread. Here we analyzed the expression of 47 genes associated with interferon (IFN) induction and signaling following HCV infection of primary human fetal liver cell (HFLC) cultures from 18 different donors. We report that cell culture-produced HCV (HCVcc) induced expression of Type III (λ) IFNs and of IFN-stimulated genes (ISGs). Little expression of Type I IFNs was detected. Levels of IFNλ and ISG induction varied among donors and, often, between adapted and nonadapted HCV chimeric constructs. Higher levels of viral replication were associated with greater induction of ISGs and of λ IFNs. Gene induction was dependent on HCV replication, as ultraviolet light-inactivated virus was not stimulatory and an antiviral drug, 2'-C-methyladenosine, reduced induction of λ IFNs and ISGs. The level of IFNλ protein induced was sufficient to inhibit HCVcc infection of na?ve cultures. Conclusion: Together, these results indicate that despite its reported abilities to blunt the induction of an IFN response, HCV infection is capable of inducing antiviral cytokines and pathways in primary liver cell cultures. Induction of ISGs and λ IFNs may limit the growth and spread of HCV in primary cell cultures and in the infected liver. HCV infection of HFLC may provide a useful model for the study of gene induction by HCV in vivo.