An update on hepatitis C virus

Long Noncoding RNA ITPRIP-1 Positively Regulates the Innate Immune Response through Promotion of Oligomerization and Activation of MDA5

Emerging evidence indicates that long noncoding RNAs (lncRNAs) regulate various biological processes, especially innate and adaptive immunity. However, the relationship between lncRNAs and the interferon (IFN) pathway remains largely unknown. Here, we report that lncRNA ITPRIP-1 (lncITPRIP-1) is involved in viral infection and plays a crucial role in the virus-triggered IFN signaling pathway through the targeting of melanoma differentiation-associated gene 5 (MDA5). LncITPRIP-1 can be induced by viral infection, which is not entirely dependent on the IFN signal. Besides, there is no coding potential found in the lncITPRIP-1 transcript. LncITPRIP-1 binds to the C terminus of MDA5, and it possesses the ability to boost the oligomerization of both the full length and the 2 caspase activation and recruitment domains of MDA5 in a K63-linked polyubiquitination-independent manner. Amazingly, we also found that MDA5 can suppress hepatitis C virus (HCV) replication independently of IFN signaling through its C-terminal-deficient domain bound to viral RNA, in which lncITPRIP-1 plays a role as an assistant. In addition, the expression of lncITPRIP-1 is highly consistent with MDA5 expression, indicating that lncITPRIP-1 may function as a cofactor of MDA5. All the data suggest that lncITPRIP-1 enhances the innate immune response to viral infection through the promotion of oligomerization and activation of MDA5. Our study discovers the first lncRNA ITPRIP-1 involved in MDA5 activation.IMPORTANCE Hepatitis C virus infection is a global health issue, and there is still no available vaccine, which makes it urgent to reveal the underlying mechanisms of HCV and host factors. Although RIG-I has been recognized as the leading cytoplasmic sensor against HCV for a long time, recent findings that MDA5 regulates the IFN response to HCV have emerged. Our work validates the significant role of MDA5 in IFN signaling and HCV infection and proposes the first lncRNA inhibiting HCV replication by promoting the activation of MDA5 and mediating the association between MDA5 and HCV RNA, the study of which may shed light on the MDA5 function and treatment for hepatitis C patients. Our suggested model of how lncITPRIP-1 orchestrates signal transduction for IFN production illustrates the essential role of lncRNAs in virus elimination.

Patient-reported outcomes with sofosbuvir and velpatasvir with or without ribavirin for hepatitis C virus-related decompensated cirrhosis: an exploratory analysis from the randomised, open-label ASTRAL-4 phase 3 trial

BACKGROUND

Hepatitis C virus (HCV) treatment regimens with direct-acting antivirals have not been extensively studied in patients with decompensated cirrhosis. We assessed patient-reported outcomes (PROs) in patients with decompensated cirrhosis given a fixed-dose combination of sofosbuvir and velpatasvir with and without ribavirin.

METHODS

This study was an exploratory analysis of data collected in a randomised, open-label phase 3 trial (ASTRAL-4) in which patients with HCV-related decompensated cirrhosis were randomly assigned to an all-oral fixed-dose combination of sofosbuvir (400 mg) and velpatasvir (100 mg) once daily for 12 weeks, sofosbuvir and velpatasvir plus oral ribavirin (weight-based 1000 mg or 1200 mg) for 12 weeks, or sofosbuvir and velpatasvir for 24 weeks. Eligible patients were aged 18 years or older with any HCV genotype and decompensated cirrhosis at screening. PROs were collected for the intention-to-treat population using four questionnaires, Short Form (36) Health Survey version 2 (SF-36v2), the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), the Chronic Liver Disease Questionnaire-HCV Version (CLDQ-HCV), and the Work Productivity Activity Index:HCV (WPAI), which were given prospectively to patients before, during, and after treatment. The ASTRAL-4 study is registered with ClinicalTrials.gov, number NCT02201901.

FINDINGS

Patients were enrolled at 47 hepatology outpatient practices in the USA from Aug 19, 2014, to Dec 19, 2014. 267 patients with HCV-related decompensated cirrhosis were included. In patients given sofosbuvir and velpatasvir for 12 weeks (n=90), clinically significant improvements in PROs started 4 weeks after treatment initiation (+4·4 to +7·5 points on a 0-100 scale at treatment week 4). By the end of treatment, mean improvements in PROs of +5·3 to +16·0 points were noted in all PROs except for role emotional, mental component summary, and social wellbeing scores and work productivity metrics by WPAI:HCV. Similar end-of-treatment improvements (+3·8 to +17·0 points) were observed in patients given sofosbuvir and velpatasvir for 24 weeks (n=90). In patients given sofosbuvir and velpatasvir plus ribavirin (n=87), PRO scores decreased within 4 weeks of treatment (-3·6 to -6·9 points), although scores returned to the baseline levels by the end of treatment. After treatment cessation, significant improvements in all PROs were similar between the treatment groups (all p>0·01) and, by post-treatment week 24, improvements were between +4·9 and +21·2 points. In multivariate analysis, predictors of PRO impairment were treatment naivety, anxiety, use of anxiolytics, use of antidepressants, use of opioids, ribavirin use, the presence of ascites, encephalopathy, insomnia, and depression.

INTERPRETATION

A clinically significant early (within 4 weeks) and sustained improvement in PROs was observed in patients with HCV-related decompensated cirrhosis who were given sofosbuvir and velpatasvir without ribavirin. A similar regimen with ribavirin resulted in a temporary decrease in PROs, which completely resolved after 8 weeks of treatment. Accompanied by high efficacy, the favourable effect of treatment on PROs improves patients' experience in this difficult-to-treat population with HCV.

FUNDING

Gilead Sciences.