scholarly journals Hepatitis C virus evades IFN signaling by suppressing long non-coding RNA Linc-Pint involving c/EBP-β

2021 ◽  
Author(s):  
Mousumi Khatun ◽  
Jinsong Zhang ◽  
Ranjit Ray ◽  
Ratna B. Ray
Keyword(s):  
Immune Response ◽  
Hepatitis C Virus ◽  
Immune System ◽  
Hepatitis C ◽  
Immune Responses ◽  
Promoter Activity ◽  
Innate Immune ◽  
Hcv Infection ◽  
Positive Regulator

Hepatitis C virus (HCV) regulates many cellular genes in modulating host immune system for benefit of viral replication and long-term persistence in a host for chronic infection. Long non-coding RNAs (lncRNAs) play an important role in the regulation of many important cellular processes, including immune responses. We recently reported that HCV infection downregulates lncRNA Linc-Pint expression, although the mechanism of repression and functional consequence are not well understood. In this study, we demonstrated that HCV infection of hepatocytes transcriptionally reduces Linc-Pint expression through CCAAT/enhancer binding protein-β (C/EBP-β). Subsequently, we observed that overexpression of Linc-Pint significantly upregulates IFN-α and IFN-β expression in HCV replicating hepatocytes. Using unbiased proteomics, we identified Linc-Pint associates with DDX24, which enables RIP1 to interact with IRF7 of IFN signaling pathway. We further observed that IFN-α-14 promoter activity was enhanced in the presence of Linc-Pint. Together, these results demonstrated that Linc-Pint acts as a positive regulator of host innate immune responses, specially IFN signaling. HCV mediated downregulation of Linc-Pint expression appeared as one of the mechanisms by which HCV may evade innate immunity for long-term persistence and chronicity. IMPORTANCE The mechanism by which lncRNA regulates host immune response during HCV infection is poorly understood. We observed that Linc-Pint was transcriptionally downregulated by HCV. Using ChIP assay, we showed inhibition of transcription factor C/EBP-β binding to the Linc-pint promoter in the presence of HCV infection. We further identified that Linc-Pint associates with DDX24 for immune modulatory function. Overexpression of Linc-Pint reduces DDX24 expression which in turn results in disruption of DDX24-RIP1 complex formation and activation of IRF7. An induction of IFN-α14 promoter activity in the presence of Linc-Pint further confirms our observation. Together, our results suggest that Linc-Pint acts as a positive regulator of host innate immune response. Downregulation of Linc-Pint expression by HCV helps in escaping innate immune system for development of chronicity.

scholarly journals Hepatitis C Virus Induces Toll-Like Receptor 4 Expression, Leading to Enhanced Production of Beta Interferon and Interleukin-6

2006 ◽  
Vol 80 (2) ◽  
pp. 866-874 ◽  
Author(s):  
Keigo Machida ◽  
Kevin T. H. Cheng ◽  
Vicky M.-H. Sung ◽  
Alexandra M. Levine ◽  
Steven Foung ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
B Cells ◽  
Immune Responses ◽  
Interleukin 6 ◽  
Innate Immune ◽  
Hcv Infection ◽  
Innate Immune Responses ◽  
Altered Expression ◽  
Beta Interferon

ABSTRACT Hepatitis C virus (HCV) induces inflammatory signals, leading to hepatitis, hepatocellular carcinomas, and lymphomas. The mechanism of HCV involvement in the host's innate immune responses has not been well characterized. In this study, we analyzed expression and regulation of the entire panel of toll-like receptors (TLRs) in human B cells following HCV infection in vitro. Among all of the TLRs (TLRs 1 to 10) examined, only TLR4 showed an altered expression (a three- to sevenfold up-regulation) after HCV infection. Peripheral blood mononuclear cells from HCV-infected individuals also showed a higher expression level of TLR4 compared with those of healthy individuals. HCV infection significantly increased beta interferon (IFN-β) and interleukin-6 (IL-6) secretion from B cells, particularly after lipopolysaccharide stimulation. The increased IFN-β and IL-6 production was mediated by TLR4 induction, since the introduction of the small interfering RNA against TLR4 specifically inhibited the HCV-induced cytokine production. Among all of the viral proteins, only NS5A caused TLR4 induction in hepatocytes and B cells. NS5A specifically activated the promoter of the TLR4 gene in both hepatocytes and B cells. In conclusion, HCV infection directly induces TLR4 expression and thereby activates B cells, which may contribute to the host's innate immune responses.

scholarly journals EFTUD2 Is a Novel Innate Immune Regulator Restricting Hepatitis C Virus Infection through the RIG-I/MDA5 Pathway

2015 ◽  
Vol 89 (13) ◽  
pp. 6608-6618 ◽  
Author(s):  
Chuanlong Zhu ◽  
Fei Xiao ◽  
Jian Hong ◽  
Kun Wang ◽  
Xiao Liu ◽  
...  
Keyword(s):  
Immune Response ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Innate Immune Response ◽  
Liver Tissue ◽  
Antiviral Effect ◽  
Innate Immune ◽  
Hcv Infection ◽  
Gene Splicing ◽  
Huh7 Cells

ABSTRACTThe elongation factor Tu GTP binding domain-containing protein 2 (EFTUD2) was identified as an anti-hepatitis C virus (HCV) host factor in our recent genome-wide small interfering RNA (siRNA) screen. In this study, we sought to further determine EFTUD2's role in HCV infection and investigate the interaction between EFTUD2 and other regulators involved in HCV innate immune (RIG-I, MDA5, TBK1, and IRF3) and JAK-STAT1 pathways. We found that HCV infection decreased the expression of EFTUD2 and the viral RNA sensors RIG-I and MDA5 in HCV-infected Huh7 and Huh7.5.1 cells and in liver tissue from in HCV-infected patients, suggesting that HCV infection downregulated EFTUD2 expression to circumvent the innate immune response. EFTUD2 inhibited HCV infection by inducing expression of the interferon (IFN)-stimulated genes (ISGs) in Huh7 cells. However, its impact on HCV infection was absent in both RIG-I knockdown Huh7 cells and RIG-I-defective Huh7.5.1 cells, indicating that the antiviral effect of EFTUD2 is dependent on RIG-I. Furthermore, EFTUD2 upregulated the expression of the RIG-I-like receptors (RLRs) RIG-I and MDA5 to enhance the innate immune response by gene splicing. Functional experiments revealed that EFTUD2-induced expression of ISGs was mediated through interaction of the EFTUD2 downstream regulators RIG-I, MDA5, TBK1, and IRF3. Interestingly, the EFTUD2-induced antiviral effect was independent of the classical IFN-induced JAK-STAT pathway. Our data demonstrate that EFTUD2 restricts HCV infection mainly through an RIG-I/MDA5-mediated, JAK-STAT-independent pathway, thereby revealing the participation of EFTUD2 as a novel innate immune regulator and suggesting a potentially targetable antiviral pathway.IMPORTANCEInnate immunity is the first line defense against HCV and determines the outcome of HCV infection. Based on a recent high-throughput whole-genome siRNA library screen revealing a network of host factors mediating antiviral effects against HCV, we identified EFTUD2 as a novel innate immune regulator against HCV in the infectious HCV cell culture model and confirmed that its expression in HCV-infected liver tissue is inversely related to HCV infection. Furthermore, we determined that EFTUD2 exerts its antiviral activity mainly through governing its downstream regulators RIG-I and MDA5 by gene splicing to activate IRF3 and induce classical ISG expression independent of the JAT-STAT signaling pathway. This study broadens our understanding of the HCV innate immune response and provides a possible new antiviral strategy targeting this novel regulator of the innate response.

scholarly journals NLRX1 Mediates MAVS Degradation To Attenuate the Hepatitis C Virus-Induced Innate Immune Response through PCBP2

2017 ◽  
Vol 91 (23) ◽  
Author(s):  
Yuwen Qin ◽  
Binbin Xue ◽  
Chunyan Liu ◽  
Xiaohong Wang ◽  
Renyun Tian ◽  
...  
Keyword(s):  
Immune Response ◽  
Innate Immunity ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Signaling Pathway ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Hcv Infection ◽  
Negative Regulator ◽  
Immune Mediated

ABSTRACT Activation of innate immunity is essential for host cells to restrict the spread of invading viruses and other pathogens. However, attenuation or termination of signaling is also necessary for preventing immune-mediated tissue damage and spontaneous autoimmunity. Here, we identify nucleotide binding oligomerization domain (NOD)-like receptor X1 (NLRX1) as a negative regulator of the mitochondrial antiviral signaling protein (MAVS)-mediated signaling pathway during hepatitis C virus (HCV) infection. The depletion of NLRX1 enhances the HCV-triggered activation of interferon (IFN) signaling and causes the suppression of HCV propagation in hepatocytes. NLRX1, a HCV-inducible protein, interacts with MAVS and mediates the K48-linked polyubiquitination and subsequent degradation of MAVS via the proteasomal pathway. Moreover, poly(rC) binding protein 2 (PCBP2) interacts with NLRX1 to participate in the NLRX1-induced degradation of MAVS and the inhibition of antiviral responses during HCV infection. Mutagenic analyses further revealed that the NOD of NLRX1 is essential for NLRX1 to interact with PCBP2 and subsequently induce MAVS degradation. Our study unlocks a key mechanism of the fine-tuning of innate immunity by which NLRX1 restrains the retinoic acid-inducible gene I-like receptor (RLR)-MAVS signaling cascade by recruiting PCBP2 to MAVS for inducing MAVS degradation through the proteasomal pathway. NLRX1, a negative regulator of innate immunity, is a pivotal host factor for HCV to establish persistent infection. IMPORTANCE Innate immunity needs to be tightly regulated to maximize the antiviral response and minimize immune-mediated pathology, but the underlying mechanisms are poorly understood. In this study, we report that NLRX1 is a proviral host factor for HCV infection and functions as a negative regulator of the HCV-triggered innate immune response. NLRX1 recruits PCBP2 to MAVS and induces the K48-linked polyubiquitination and degradation of MAVS, leading to the negative regulation of the IFN signaling pathway and promoting HCV infection. Overall, this study provides intriguing insights into how innate immunity is regulated during viral infection.

scholarly journals Identification of Cholesterol 25-Hydroxylase as a Novel Host Restriction Factor and a Part of the Primary Innate Immune Responses against Hepatitis C Virus Infection

2015 ◽  
Vol 89 (13) ◽  
pp. 6805-6816 ◽  
Author(s):  
Yu Xiang ◽  
Jing-Jie Tang ◽  
Wanyin Tao ◽  
Xuezhi Cao ◽  
Bao-Liang Song ◽  
...  
Keyword(s):  
Immune Response ◽  
Lipid Metabolism ◽  
Hepatitis C ◽  
Immune Responses ◽  
Host Response ◽  
Innate Immune ◽  
Hcv Infection ◽  
Innate Response ◽  
Viral Pathogens ◽  
Host Innate Immune Response

ABSTRACTHepatitis C virus (HCV), a single-stranded positive-sense RNA virus of theFlaviviridaefamily, causes chronic liver diseases, including hepatitis, cirrhosis, and cancer. HCV infection is critically dependent on host lipid metabolism, which contributes to all stages of the viral life cycle, including virus entry, replication, assembly, and release. 25-Hydroxycholesterol (25HC) plays a critical role in regulating lipid metabolism, modulating immune responses, and suppressing viral pathogens. In this study, we showed that 25HC and its synthesizing enzyme cholesterol 25-hydroxylase (CH25H) efficiently inhibit HCV infection at a postentry stage. CH25H inhibits HCV infection by suppressing the maturation of SREBPs, critical transcription factors for host lipid biosynthesis. Interestingly, CH25H is upregulated upon poly(I·C) treatment or HCV infection in hepatocytes, which triggers type I and III interferon responses, suggesting that the CH25H induction constitutes a part of host innate immune response. To our surprise, in contrast to studies in mice, CH25H is not induced by interferons in human cells and knockdown of STAT-1 has no effect on the induction of CH25H, suggesting CH25H is not an interferon-stimulated gene in humans but rather represents a primary and direct host response to viral infection. Finally, knockdown of CH25H in human hepatocytes significantly increases HCV infection. In summary, our results demonstrate that CH25H constitutes a primary innate response against HCV infection through regulating host lipid metabolism. Manipulation of CH25H expression and function should provide a new strategy for anti-HCV therapeutics.IMPORTANCERecent studies have expanded the critical roles of oxysterols in regulating immune response and antagonizing viral pathogens. Here, we showed that one of the oxysterols, 25HC and its synthesizing enzyme CH25H efficiently inhibit HCV infection at a postentry stage via suppressing the maturation of transcription factor SREBPs that regulate lipid biosynthesis. Furthermore, we found that CH25H expression is upregulated upon poly(I·C) stimulation or HCV infection, suggesting CH25H induction constitutes a part of host innate immune response. Interestingly, in contrast to studies in mice showing thatch25his an interferon-stimulated gene, CH25H cannot be induced by interferons in human cells but rather represents a primary and direct host response to viral infection. Our studies demonstrate that the induction of CH25H represents an important host innate response against virus infection and highlight the role of lipid effectors in host antiviral strategy.

A Serological Storm

1970 ◽  
Vol 9 (2) ◽  
Author(s):  
Bertha Wong MD ◽  
Maria Bagovich MD ◽  
Ivan Blasutig PhD ◽  
Simon Carette MD MPhil
Keyword(s):  
Differential Diagnosis ◽  
Hepatitis C Virus ◽  
Immune System ◽  
Hepatitis C ◽  
Hcv Infection ◽  
Clinical Context ◽  
Autoantibody Profile ◽  
Life Threatening ◽  
Clinically Significant ◽  
Sensory Polyneuropathy

This article describes a patient presenting with a sensory polyneuropathy and multiple autoantibodies, leading to the diagnosis of hepatitis C virus (HCV) infection. His widely positive autoantibody profile in the absence of clinically significant rheumatic disease illustrates the importance of interpreting autoimmune serology in the appropriate clinical context and the concept of HCV being a non-specific activator of the immune system. In addition, it highlights the importance of considering untreated HCV infection in the differential diagnosis of rheumatic complaints, particularly if the workup reveals multiple autoantibodies, as HCV is a potentially severe and life-threatening disease, which can be appropriately managed with effective antiviral therapy.

Enhanced immune responses, PI3K/AKT and JAK/STAT signaling pathways following hepatitis C virus eradication by direct-acting antiviral therapy among Egyptian patients: a case control study

2021 ◽  
Author(s):  
Haidi Karam-Allah Ramadan ◽  
Gamal Badr ◽  
Nancy K Ramadan ◽  
Aml Sayed
Keyword(s):  
Immune Response ◽  
Liver Cirrhosis ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Immune Responses ◽  
Signaling Pathways ◽  
Liver Diseases ◽  
Stat Signaling ◽  
Chronic Hcv ◽  
Direct Acting

Abstract The use of direct-acting antivirals (DAAs) therapy for the treatment of hepatitis C virus (HCV) results in a high sustained virological response (SVR) and subsequently alters liver immunologic environment. However, hepatocellular carcinoma (HCC) may occur after DAAs treatment. We aimed to clarify changes of immune responses, PI3K/AKT and JAK/STAT signaling pathways in HCV-induced liver diseases and HCC following DAAs treatment. Four cohorts are classified as chronic HCV patients, HCV-related cirrhosis without HCC, HCV-related cirrhosis and HCC, and healthy control group. The patient groups were further divided into treated or untreated with DAAs with SVR12. Increased percentages of CD3, CD8 and CD4, decreased CD4/FoxP3/CD25, CD8/PD-1 and CD19/PDL-1 were found in DAAs-treated patients in the three HCV groups. Following DAAs therapy, the levels of ROS, IL-1β, IL-6, IL-8 and TNF-α were significantly decreased in the three HCV groups. Treated HCV patients showed up regulation of p-AKT and p-STAT5 and down regulation of p-STAT3, HIF-1α and COX-2. In conclusion, DAAs enhance the immune response in chronic HCV and liver cirrhosis, hence our study is the first to show change in PI3K/AKT and JAK/STAT signaling pathways in different HCV-induced liver diseases after DAAs. In chronic HCV, DAAs have better impact on the immune response while in liver cirrhosis not all immune changes were prominent.

scholarly journals The Hepatitis C Virus-Induced Membranous Web in Liver Tissue

Cells ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 191
Author(s):  
Emmanuelle Blanchard ◽  
Philippe Roingeard
Keyword(s):  
Immune Response ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Innate Immune Response ◽  
Liver Tissue ◽  
Hepatoma Cell ◽  
Membrane Vesicles ◽  
Innate Immune ◽  
Host Cell Membrane

Host cell membrane rearrangements induced by the hepatitis C virus (HCV) have been exclusively studied in vitro. These studies have shown that HCV induces double-membrane vesicles (DMVs), which probably serve to separate replication sites from the cytoplasmic sensors of the innate immune response. We report for the first time the observation of HCV-induced membrane rearrangements in liver biopsy specimens from patients chronically infected with HCV. Unlike observations performed in vitro, the membranous web detected in liver tissue seems essentially made of clusters of single-membrane vesicles derived from the endoplasmic reticulum and close to lipid droplets. This suggests that the DMVs could be a hallmark of laboratory-adapted HCV strains, possibly due to their ability to achieve a high level of replication. Alternatively, the concealment of viral RNA in DMVs may be part of innate immune response mechanisms particularly developed in hepatoma cell lines cultured in vitro. In any case, this constitutes the first report showing the differences in the membranous web established by HCV in vitro and in vivo.

scholarly journals Chronic hepatitis C virus infections in Brazilian patients: association with genotypes, clinical parameters and response to long term alpha interferon therapy

1999 ◽  
Vol 41 (3) ◽  
pp. 183-189 ◽  
Author(s):  
Leda BASSIT ◽  
Luiz C. DA SILVA ◽  
Gabriela RIBEIRO-DOS-SANTOS ◽  
Geert MAERTENS ◽  
Flair J. CARRILHO ◽  
...  
Keyword(s):  
Chronic Hepatitis ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Chronic Hepatitis C ◽  
Hcv Infection ◽  
Sustained Response ◽  
Response To Treatment ◽  
Recombinant Interferon ◽  
Genotype 2

The present study assessed the clinical significance of hepatitis C virus (HCV) genotypes and their influence on response to long term recombinant-interferon-alpha (r-IFN-<FONT FACE="Symbol">a</FONT>) therapy in Brazilian patients. One hundred and thirty samples from patients previously genotyped for the HCV and with histologically confirmed chronic hepatitis C (CH-C) were evaluated for clinical and epidemiological parameters (sex, age, time of HCV infection and transmission routes). No difference in disease activity, sex, age or mode and time of transmission were seen among patients infected with HCV types 1, 2 or 3. One hundred and thirteen of them were treated with 3 million units of r-IFN-<FONT FACE="Symbol">a</FONT>, 3 times a week for 12 months. Initial response (IR) was significantly better in patients with genotype 2 (100%) and 3 (46%) infections than in patients with genotype 1 (29%) (p < 0.005). Among subtypes, difference in IR was observed between 1b and 2 (p < 0.005), and between 1b and 3a (p < 0.05). Sustained response (SR) was observed in 12% for (sub)type 1a, 13% for 1b, 19% for 3a, and 40% for type 2; significant differences were found between 1b and 2 (p < 0.001), and between 1b and 3a (p < 0.05). Moreover, presence of cirrhosis was significantly associated with non response and response with relapse (p < 0.05). In conclusion, non-1 HCV genotype and lack of histological diagnosis of cirrhosis were the only baseline features associated with sustained response to treatment. These data indicate that HCV genotyping may have prognostic relevance in the responsiveness to r-IFN-<FONT FACE="Symbol">a</FONT> therapy in Brazilian patients with chronic HCV infection, as seen in other reports worldwide.

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