Evasion of intracellular host defence by hepatitis C virus

The HTLV-I oncoprotein Tax inactivates the tumor suppressor FBXW7

Human T-cell leukemia virus type 1 (HTLV-I) is the etiological agent of adult T-cell leukemia (ATL). Mutational analysis has demonstrated that the tumor suppressor, F-box and WD repeat domain containing 7 (FBXW7/FBW7/CDC4), is mutated in primary ATL patients. However, even in the absence of genetic mutations, FBXW7 substrates are stabilized in ATL cells, suggesting additional mechanisms can prevent FBXW7 functions. Here, we report that the viral oncoprotein Tax represses FBXW7 activity, resulting in the stabilization of activated Notch intracellular domain, c-MYC, Cyclin E, and myeloid cell leukemia sequence 1 (BCL2-related) (Mcl-1). Mechanistically, we demonstrate that Tax directly binds to FBXW7 in the nucleus, effectively outcompeting other targets for binding to FBXW7, resulting in decreased ubiquitination and degradation of FBXW7 substrates. In support of the nuclear role of Tax, a non-degradable form of the nuclear factor kappa B subunit 2 (NFκB2/p100) was found to delocalize Tax to the cytoplasm, thereby preventing Tax interactions with FBXW7 and Tax-mediated inhibition of FBXW7. Finally, we characterize a Tax mutant that is unable to interact with FBXW7, unable to block FBXW7 tumor suppressor functions, and unable to effectively transform fibroblasts. These results demonstrate that HTLV-I Tax can inhibit FBXW7 functions without genetic mutations to promote an oncogenic state. These results suggest that Tax-mediated inhibition of FBXW7 is likely critical during the early stages of the cellular transformation process.

IMPORTANCE

F-box and WD repeat domain containing 7 (FBXW7), a critical tumor suppressor of human cancers, is frequently mutated or epigenetically suppressed. Loss of FBXW7 functions is associated with stabilization and increased expression of oncogenic factors such as Cyclin E, c-Myc, Mcl-1, mTOR, Jun, and Notch. In this study, we demonstrate that the human retrovirus human T-cell leukemia virus type 1 oncoprotein Tax directly interacts with FBXW7, effectively outcompeting other targets for binding to FBXW7, resulting in decreased ubiquitination and degradation of FBXW7 cellular substrates. We further demonstrate that a Tax mutant unable to interact with and inactivate FBXW7 loses its ability to transform primary fibroblasts. Collectively, our results describe a novel mechanism used by a human tumor virus to promote cellular transformation.

Hepatitis C Virus and the Host: A Mutual Endurance Leaving Indelible Scars in the Host's Immunity

Hepatitis C virus (HCV) has spread worldwide, and it is responsible for potentially severe chronic liver disease and primary liver cancer. Chronic infection remains for life if not spontaneously eliminated and viral persistence profoundly impairs the efficiency of the host's immunity. Attempts have been made to develop an effective vaccine, but efficacy trials have met with failure. The availability of highly efficacious direct-acting antivirals (DAA) has created hope for the progressive elimination of chronic HCV infections; however, this approach requires a monumental global effort. HCV elicits a prompt innate immune response in the host, characterized by a robust production of interferon-α (IFN-α), although interference in IFN-α signaling by HCV proteins may curb this effect. The late appearance of largely ineffective neutralizing antibodies and the progressive exhaustion of T cells, particularly CD8 T cells, result in the inability to eradicate the virus in most infected patients. Moreover, an HCV cure resulting from DAA treatment does not completely restore the normal immunologic homeostasis. Here, we discuss the main immunological features of immune responses to HCV and the epigenetic scars that chronic viral persistence leaves behind.

Suppression of Innate Immunity by the Hepatitis C Virus (HCV): Revisiting the Specificity of Host-Virus Interactive Pathways

The hepatitis C virus (HCV) is a major causative agent of hepatitis that may also lead to liver cancer and lymphomas. Chronic hepatitis C affects an estimated 2.4 million people in the USA alone. As the sole member of the genus Hepacivirus within the Flaviviridae family, HCV encodes a single-stranded positive-sense RNA genome that is translated into a single large polypeptide, which is then proteolytically processed to yield the individual viral proteins, all of which are necessary for optimal viral infection. However, cellular innate immunity, such as type-I interferon (IFN), promptly thwarts the replication of viruses and other pathogens, which forms the basis of the use of conjugated IFN-alpha in chronic hepatitis C management. As a countermeasure, HCV suppresses this form of immunity by enlisting diverse gene products, such as HCV protease(s), whose primary role is to process the large viral polyprotein into individual proteins of specific function. The exact number of HCV immune suppressors and the specificity and molecular mechanism of their action have remained unclear. Nonetheless, the evasion of host immunity promotes HCV pathogenesis, chronic infection, and carcinogenesis. Here, the known and putative HCV-encoded suppressors of innate immunity have been reviewed and analyzed, with a predominant emphasis on the molecular mechanisms. Clinically, the knowledge should aid in rational interventions and the management of HCV infection, particularly in chronic hepatitis.

Aminoacyl-tRNA synthetase - a molecular multitasker

Aminoacyl-tRNA synthetases (AaRSs) are valuable "housekeeping" enzymes that ensure the accurate transmission of genetic information in living cells, where they aminoacylated tRNA molecules with their cognate amino acid and provide substrates for protein biosynthesis. In addition to their translational or canonical function, they contribute to nontranslational/moonlighting functions, which are mediated by the presence of other domains on the proteins. This was supported by several reports which claim that AaRS has a significant role in gene transcription, apoptosis, translation, and RNA splicing regulation. Noncanonical/ nontranslational functions of AaRSs also include their roles in regulating angiogenesis, inflammation, cancer, and other major physio-pathological processes. Multiple AaRSs are also associated with a broad range of physiological and pathological processes; a few even serve as cytokines. Therefore, the multifunctional nature of AaRSs suggests their potential as viable therapeutic targets as well. Here, our discussion will encompass a range of noncanonical functions attributed to Aminoacyl-tRNA Synthetases (AaRSs), highlighting their links with a diverse array of human diseases.

Looking at the Molecular Target of NS5A Inhibitors throughout a Population Highly Affected with Hepatitis C Virus

Hepatitis C virus (HCV) is associated with liver damage and an increased progression rate to cirrhosis and hepatocellular carcinoma. In Portugal, it is prevalent in vulnerable populations such as injection drug users (IDU). HCV is characterized by a high intra-host variability, and the selecting driving forces could select variants containing resistance-associated substitutions (RAS) that reduce treatment effectiveness. The main goal of this study was to analyze the sequence variation of NS5A in treatment-naïve IDU. The epidemiological and clinical status of hepatitis C were analyzed, and samples were sequenced by Sanger and Next-Generation sequencing (NGS) to assess RAS and confirm HCV subtypes. Phylogenetic classification was concordant: 1a, 52.4%; 1b, 10.7%; 3a, 20.2%; 4a, 8.3%; 4d, 7.1%; and one 2k/1b recombinant. A 1a/3a mixed infection was detected by NGS. RAS were found in 34.5% (29/84) of samples using Sanger sequencing, while in 42.9% (36/84) using NGS. In sequences from subtypes 1a and 1b, RAS K24R, M28V, Q30H/R, H58D/P/Q/R, and RAS L31M and P58S were detected, respectively. In subtype 3a, RAS A30S/T, Y93H and polymorphisms in position 62 were identified. Additionally, RAS P58L was detected in genotype 4. The strategy used for the molecular survey of baseline HCV resistance is of particular importance to achieve treatment effectiveness and contribute to the elimination of hepatitis C.

Susceptibilidad genética y aclaramiento viral de la infección por Virus de la Hepatitis C

El virus de la hepatitis C (VHC) sigue siendo una de las principales causas de hepatitis crónica en el mundo occidental. Del 15 % al 40 % de los individuos con infección aguda por VHC logran el aclaramiento viral espontáneo; sin embargo, los factores y variables asociadas a este fenómeno no están completamente descritas. El análisis de los mecanismos de patogénesis de la infección por VHC es indispensable para identificar los factores y variables implicadas en el aclaramiento espontáneo o en la persistencia de la infección. En algunos estudios se han documentado los factores del huésped asociados al aclaramiento viral espontáneo durante la infección aguda, entre ellos el polimorfismo del gen de la interleucina -28 (IL28B) que codifica para el interferón lambda 3 (IFNL3). El objetivo de este artículo es realizar una revisión de la literatura sobre la fisiopatología de la infección por el VHC y describir la evidencia acerca del papel de los polimorfismos en el gen IL28B y su impacto en el proceso de aclaramiento viral espontáneo, así como en otros aspectos de la historia natural y el tratamiento de la infección.

Host cellular RNA helicases regulate SARS-CoV-2 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has the largest RNA genome, approximately 30 kb, among RNA viruses. The DDX DEAD box RNA helicase is a multifunctional protein involved in all aspects of RNA metabolism. Therefore, host RNA helicases may regulate and maintain such a large viral RNA genome. In this study, I investigated the potential role of several host cellular RNA helicases in SARS-CoV-2 infection. Notably, DDX21 knockdown markedly accumulated intracellular viral RNA and viral production, as well as viral infectivity of SARS-CoV-2, indicating that DDX21 strongly restricts the SARS-CoV-2 infection. In addition, MOV10 RNA helicase also suppressed the SARS-CoV-2 infection. In contrast, DDX1, DDX5, and DDX6 RNA helicases were required for SARS-CoV-2 replication. Indeed, SARS-CoV-2 infection dispersed the P-body formation of DDX6 and MOV10 RNA helicases as well as XRN1 exonuclease, while the viral infection did not induce stress granule formation. Accordingly, the SARS-CoV-2 nucleocapsid (N) protein interacted with DDX1, DDX3, DDX5, DDX6, DDX21, and MOV10 and disrupted the P-body formation, suggesting that SARS-CoV-2 N hijacks DDX6 to carry out viral replication. Conversely, DDX21 and MOV10 restricted SARS-CoV-2 infection through an interaction of SARS-CoV-2 N with host cellular RNA helicases. Altogether, host cellular RNA helicases seem to regulate the SARS-CoV-2 infection.

IMPORTANCE SARS-CoV-2 has a large RNA genome, of approximately 30 kb. To regulate and maintain such a large viral RNA genome, host RNA helicases may be involved in SARS-CoV-2 replication. In this study, I have demonstrated that DDX21 and MOV10 RNA helicases limit viral infection and replication. In contrast, DDX1, DDX5, and DDX6 are required for SARS-CoV-2 infection. Interestingly, SARS-CoV-2 infection disrupted P-body formation and attenuated or suppressed stress granule formation. Thus, SARS-CoV-2 seems to hijack host cellular RNA helicases to play a proviral role by facilitating viral infection and replication and by suppressing the host innate immune system.

The Role of Macrophage-Derived Exosomes in Liver Diseases

Abstract

Exosomes (exos) widely distributed in a variety of biological fluids, including blood, urine, saliva, sputum, breast milk, cerebrospinal fluid, and ascites, contain specific bioactive contents which are involved in physiological and pathological processes, such as signal molecular transfer, substance metabolism, gene regulation, and immune regulation. Macrophages are important innate immune cells which usually act as the first line of defense against infection, and can switch between different functional phenotypes in response to the changes around the microenvironment. Evidence suggests that macrophage-derived exos exert a crucial effect on infection, inflammation, regeneration, tumors, fibrosis, and other lesions in multiple human diseases. However, the role and mechanism of macrophage-derived exos in liver diseases remain to be explored. This review summarizes the current researches on the role and possible mechanism of macrophage-derived exos in liver diseases, with the purpose of providing new potential targets and directions for diagnostic biomarker and clinical treatment of liver diseases.

Effects of infections on the pathogenesis of cancer

Several studies have shown an inverse relationship between acute infections and cancer development. On the other hand, there is a growing evidence that chronic infections may contribute significantly to the carcinogenesis. Factors responsible for increased susceptibility to infections may include modifications of normal defence mechanisms or impairment of host immunity due to altered immune function, genetic polymorphisms, ageing and malnourishment. Studies have demonstrated that children exposed to febrile infectious diseases show a subsequent reduced risk for ovarian cancer, melanoma and many other cancers, while common acute infections in adults are associated with reduced risks for melanoma, glioma, meningioma and multiple cancers. Chronic inflammation associated with certain infectious diseases has been suggested as a cause for the development of tumours. Mechanisms of carcinogenesis due to infections include cell proliferation and DNA replication by mitogen-activated protein kinase pathway, production of toxins that affect the cell cycle and lead to abnormal cell growth and inhibition of apoptosis. This review was aimed to summarize the available evidence on acute infections as a means of cancer prevention and on the role of chronic infections in the development and progression of cancer.

Berberis lyceum and Fumaria indica: in vitro cytotoxicity, antioxidant activity, and in silico screening of their selected phytochemicals as novel hepatitis C virus nonstructural protein 5A inhibitors

Berberis lyceum and Fumaria indica are two Pakistani indigenous herbal medicines used to treat liver infections, including hepatitis C virus (HCV). This study aimed to evaluate the cytotoxicity, and antioxidant activity of these plant extracts and computationally screen their selected phytoconstituents as HCV NS5A inhibitors. The viability of HepG2 cells was assessed 24 h and 48 h post-treatment using colorimetric and dye exclusion methods. Antioxidant properties were examined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH), reducing power, and total antioxidant capacity assays. Seventeen known phytochemicals identified from each plant were docked into the active binding site of HCV NS5A protein. The top hit ligands were analyzed for their druglikeness properties and the indices of absorption, distribution, metabolism, elimination, and toxicity (ADMET). The results showed that both plant extracts were non-toxic (CC₅₀ > 200 µg/ml). The IC₅₀ values of DPPH-radical scavenging activity were 51.02 ± 0.94 and 62.91 ± 1.85 µg/ml for B. lyceum and F. indica, respectively. They also exhibited reducing power and total antioxidant capacity.The phytochemicals were identified as potent HCV NS5A inhibitors with good druglikeness and ADMET properties. Six of the docked phytochemicals exhibited higher binding scores (-17.9 to -19.2 kcal/mol) with HCV NS5A protein than the standard drug, daclatasvir (-17.2 kcal/mol). Molecular dynamics (MD) simulation confirmed the stability of two compounds, berbamine and paprafumine at 100 ns with active site of HCV NS5A protein. The identified compounds through molecular docking and MD simulation could have potential as HCV NS5A inhibitor after further validation. Communicated by Ramaswamy H. Sarma.

Mobilization of γδ T Cells and IL-10 Production at the Acute Phase of Hepatitis E Virus Infection in Cytomegalovirus Carriers

Alterations in the γδ T cell compartment have been reported in immunocompromised individuals infected with hepatitis E virus (HEV)-g3. We now report the analysis of blood γδ T cells from acutely HEV-infected individuals in the absence of immunosuppression. In these patients, non-Vδ2 (ND2) γδ T cells outnumbered otherwise predominant Vδ2 cells selectively in human CMV (HCMV)-seropositive patients and were higher than in HCMV^pos controls, mimicking HCMV reactivation, whereas their serum was PCR-negative for HCMV. Stimulation of their lymphocytes with HEV-infected hepatocarcinoma cells led to an HEV-specific response in γδ subsets of HCMV^pos individuals. HEV infection was associated with a lowered expression of TIGIT, LAG-3, and CD160 immune checkpoint markers on ND2 effector memory cells in HCMV^neg but not in HCMV^pos HEV patients. γδ cell lines, predominantly ND2, were generated from patients after coculture with hepatocarcinoma cells permissive to HEV and IL-2/12/18. Upon restimulation with HEV-infected or uninfected cells and selected cytokines, these cell lines produced IFN-γ and IL-10, the latter being induced by IL-12 in IFN-γ-producing cells and upregulated by HEV and IL-18. They were also capable of suppressing the proliferation of CD3/CD28-activated CD4 cells in transwell experiments. Importantly, IL-10 was detected in the plasma of 10 of 10 HCMV^pos HEV patients but rarely in controls or HCMV^neg HEV patients, implying that γδ cells are probably involved in IL-10 production at the acute phase of infection. Our data indicate that HEV mobilizes a pool of ND2 memory cells in HCMV carriers, promoting the development of an immunoregulatory environment.

Directed attenuation to enhance vaccine immunity

Many viral infections can be prevented by immunizing with live, attenuated vaccines. Early methods of attenuation were hit-and-miss, now much improved by genetic engineering. However, even current methods operate on the principle of genetic harm, reducing the virus’s ability to grow. Reduced viral growth has the undesired side-effect of reducing the host immune response below that of infection with wild-type. Might some methods of attenuation instead lead to an increased immune response? We use mathematical models of the dynamics of virus with innate and adaptive immunity to explore the tradeoff between attenuation of virus pathology and immunity. We find that modification of some virus immune-evasion pathways can indeed reduce pathology yet enhance immunity. Thus, attenuated vaccines can, in principle, be directed to be safe yet create better immunity than is elicited by the wild-type virus.

Live attenuated virus vaccines are among the most effective interventions to combat viral infections. Historically, the mechanism of attenuation has involved genetically reducing the viral growth rate, often achieved by adapting the virus to grow in a novel condition. More recent attenuation methods use genetic engineering but also are thought to impair viral growth rate. These classical attenuations typically result in a tradeoff whereby attenuation depresses the within-host viral load and pathology (which is beneficial to vaccine design), but reduces immunity (which is not beneficial). We use models to explore ways of directing the attenuation of a virus to avoid this tradeoff. We show that directed attenuation by interfering with (some) viral immune-evasion pathways can yield a mild infection but elicit higher levels of immunity than of the wild-type virus.

IgE antibodies to hepatitis C virus core and nonstructural antigens in chronic hepatitis C patients before and after antiviral treatment

Few studies on the immunoglobulin E (IgE) immune response in chronic hepatitis C have been reported. In this study, we tested the antigenicity of commercial recombinant hepatitis C virus (HCV) core and nonstructural protein NS3, NS4, and NS5 antigens and the IgE immune response to these antigens in chronic hepatitis C patients before and after antiviral treatment with pegylated interferon (IFN)-α plus ribavirin for 12 weeks. The effects of antiviral treatment were investigated in 20 out of 35 participants. We developed amplified immunoassays using these antigens and IgG-depleted patient sera. Seropositivity for IgE antibodies was determined, and serum IgE and cytokine levels were measured. Anti-core, anti-NS3, and anti-NS4 IgE antibodies were observed in most patients, whereas anti-NS5 antibodies were less prevalent. Antiviral treatment decreased the production of anti-core, anti-NS3, and anti-NS4 IgE antibodies, but not anti-NS5 IgE antibodies. A significant decrease in the anti-NS3 and anti-NS4 IgE antibody levels was observed in patients who presented with an early sustained virological response, but no effects on anti-core and anti-NS5 IgE antibodies was observed. The serum levels of IFN-γ, interleukin (IL)-2, IL-6, tumor necrosis factor-α, and IL-10, but not IL-4, were similar between patients before and after antiviral therapy. Thus, the immune response of IgE antibodies to HCV antigens was comparable to that of anti-HCV IgG antibodies. The usefulness of anti-NS3 IgE antibodies in diagnosing occult hepatitis C and monitoring antiviral treatment with directly acting antiviral medication must be investigated in future studies.

Discovery and Development of Antiviral Therapies for Chronic Hepatitis C Virus Infection

At the beginning of this decade, an estimated 71 million people were living with chronic hepatitis C virus (HCV) infection worldwide. After the acute stage of HCV infection, 18-34% of individuals exhibit spontaneous clearance. However, the remaining 66-82% of infected individuals progress to chronic HCV infection and are at subsequent risk of progression to hepatic fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Chronic hepatitis C progression is generally slow during the first two decades of infection, but can be accelerated during this time in association with advancing age and cofactors, such as heavy alcohol intake and human immunodeficiency virus (HIV) co-infection. Since acute HCV infection is generally asymptomatic, HCV goes undiagnosed in a significant percentage of infected individuals. In 2014, direct-acting antiviral (DAA) therapy for chronic HCV was developed, which has increased the cure rates to nearly 100%. DAA therapy is among the best examples of success in the fight against viral infections. DAAs have transformed HCV management and have opened the door for the global eradication of HCV.

Decreased expression of interferon-stimulated genes in B cells of patients with chronic hepatitis C during interferon-free therapy potentially suggests the eradication of hepatitis C virus in the B cells: A cohort study

AIMS

Hepatitis C virus (HCV) infection is monitored by the host innate immunity that includes the endogenous interferon (IFN), which up-regulates IFN-stimulated genes (ISGs). HCV is both hepatotropic and lymphotropic, but HCV replication in lymphoid cells is a controversial issue. Here, we analyzed the mRNA levels of the ISGs in B cells of HCV-infected patients during antiviral therapy and investigated the effects of viral eradication.

METHODS

One hundred and eighty-one patients with chronic hepatitis C and 26 healthy volunteers were enrolled in this study. Levels of HCV RNA and mRNA of ISGs in B cells isolated from the patients were monitored before, during, and after antiviral therapy.

RESULTS

HCV RNA was detected in B cells of 133/175 (76.0%) patients who achieved sustained virologic response (SVR) before therapy was started. The positive ratio of HCV RNA in B cells was higher in patients with genotype 1 and the non-major genotype of interleukin 28B. HCV RNA in B cells of most patients disappeared 1 week after antiviral therapy was started. The baseline expression of ISG mRNA was significantly higher in the patients than in the healthy volunteers. Levels of ISG mRNA were increased and remained high throughout the IFN-based therapy. In contrast, levels of ISG mRNA in patients who achieved SVR were significantly decreased 1 week after the IFN-free therapy was started and remained low during the therapy.

CONCLUSIONS

These results suggested that IFN-free therapy potentially eradicated HCV in the B cells, leading to the down-regulation of endogenous ISGs. The level of ISG mRNA could be used as a marker for viral eradication in B cells.

Rewiring Host Signaling: Hepatitis C Virus in Liver Pathogenesis

Hepatitis C virus (HCV) is a major cause of liver disease including metabolic disease, fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). HCV induces and promotes liver disease progression by perturbing a range of survival, proliferative, and metabolic pathways within the proinflammatory cellular microenvironment. The recent breakthrough in antiviral therapy using direct-acting antivirals (DAAs) can cure >90% of HCV patients. However, viral cure cannot fully eliminate the HCC risk, especially in patients with advanced liver disease or comorbidities. HCV induces an epigenetic viral footprint that promotes a pro-oncogenic hepatic signature, which persists after DAA cure. In this review, we summarize the main signaling pathways deregulated by HCV infection, with potential impact on liver pathogenesis. HCV-induced persistent signaling patterns may serve as biomarkers for the stratification of HCV-cured patients at high risk of developing HCC. Moreover, these signaling pathways are potential targets for novel chemopreventive strategies.

Expression of SOCS1 and SOCS3 Genes in Interferon-Treated and Direct-Acting Antiviral Drugs-Treated Hepatitis C Patients

Genetics of host plays a significant role in susceptibility and pathogenesis of disease. During hepatitis C virus (HCV) infection, HCV proteins interfere with interferon (IFN) signaling pathways and upregulate transcription of suppressor of cytokine signaling 1 and 3 genes (SOCS1 and SOCS3), which results in impaired immune response. In this study, we evaluated relative expression of SOCS1 and SOCS3 in untreated HCV patients and patients treated with 2 different treatment strategies that are, (IFN therapy and direct-acting antiviral (DAA) drug regimen. To study gene expression, peripheral blood mononuclear cells (PBMCs) were isolated by using Histopaque. Total RNA was extracted from PBMCs by using BIOzol. Nine microgram of total RNA from each sample was used and reverse transcribed into single-stranded complementary DNA (cDNA) by using M-MLV reverse transcriptase (Invitrogen). The synthesized cDNA was diluted to a final concentration of 500 ng/μL. This diluted cDNA was further used for expression analysis of SOCS1and SOCS3 genes using Rotor Gene Q Real-Time PCR Detection System (QIAGEN). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was amplified as a housekeeping gene. We found that the SOCS1 expression in IFN and DAA-treated patient groups was 5.4 fold and 1.2 fold, respectively, high compared with the healthy controls (IFN versus healthy, P = 0.019 and DAA versus healthy, P = 0.91), whereas the SOCS3 expression in IFN and DAA-treated patient groups was 3.7 fold and 2 fold, respectively, high in comparison with the expression in healthy controls (IFN versus healthy, P = 0.025 and DAA versus healthy, P = 0.03). We also found a significant difference in the relative expression of SOCS1 and SOCS3 in DAAs-treated and IFN/ribavirin (RBV)-treated and untreated individual. We concluded that by targeting HCV proteins with DAAs, SOCS1, and SOCS3 transcription can be more effectively normalized compared to the treatment with IFN/RBV therapy.

DNA methylation of individual repetitive elements in hepatitis C virus infection-induced hepatocellular carcinoma

Background

The two most common repetitive elements (REs) in humans, long interspersed nuclear element-1 (LINE-1) and Alu element (Alu), have been linked to various cancers. Hepatitis C virus (HCV) may cause hepatocellular carcinoma (HCC) by suppressing host defenses, through DNA methylation that controls the mobilization of REs. We aimed to investigate the role of RE methylation in HCV-induced HCC (HCV-HCC).

Results

We studied methylation of over 30,000 locus-specific REs across the genome in HCC, cirrhotic, and healthy liver tissues obtained by surgical resection. Relative to normal liver tissue, we observed the largest number of differentially methylated REs in HCV-HCC followed by alcohol-induced HCC (EtOH-HCC). After excluding EtOH-HCC-associated RE methylation (FDR < 0.001) and those unable to be validated in The Cancer Genome Atlas (TCGA), we identified 13 hypomethylated REs (11 LINE-1 and 2 Alu) and 2 hypermethylated REs (1 LINE-1 and 1 Alu) in HCV-HCC (FDR < 0.001). A majority of these REs were located in non-coding regions, preferentially enriched with chromatin repressive marks H3K27me3, and positively associated with gene expression (median correlation r = 0.32 across REs). We further constructed an HCV-HCC RE methylation score that distinguished HCV-HCC (lowest score), HCV-cirrhosis, and normal liver (highest score) in a dose-responsive manner (p for trend < 0.001). HCV-cirrhosis had a lower score than EtOH-cirrhosis (p = 0.038) and HCV-HCC had a lower score than EtOH-HCC in TCGA (p = 0.024).

Conclusions

Our findings indicate that HCV infection is associated with loss of DNA methylation in specific REs, which could implicate molecular mechanisms in liver cancer development. If our findings are validated in larger sample sizes, methylation of these REs may be useful as an early detection biomarker for HCV-HCC and/or a target for prevention of HCC in HCV-positive individuals.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0733-y) contains supplementary material, which is available to authorized users.

HCV and flaviviruses hijack cellular mechanisms for nuclear STAT2 degradation: Up-regulation of PDLIM2 suppresses the innate immune response

Host encounters with viruses lead to an innate immune response that must be rapid and broadly targeted but also tightly regulated to avoid the detrimental effects of unregulated interferon expression. Viral stimulation of host negative regulatory mechanisms is an alternate method of suppressing the host innate immune response. We examined three key mediators of the innate immune response: NF-KB, STAT1 and STAT2 during HCV infection in order to investigate the paradoxical induction of an innate immune response by HCV despite a multitude of mechanisms combating the host response. During infection, we find that all three are repressed only in HCV infected cells but not in uninfected bystander cells, both in vivo in chimeric mouse livers and in cultured Huh7.5 cells after IFNα treatment. We show here that HCV and Flaviviruses suppress the innate immune response by upregulation of PDLIM2, independent of the host interferon response. We show PDLIM2 is an E3 ubiquitin ligase that also acts to stimulate nuclear degradation of STAT2. Interferon dependent relocalization of STAT1/2 to the nucleus leads to PDLIM2 ubiquitination of STAT2 but not STAT1 and the proteasome-dependent degradation of STAT2, predominantly within the nucleus. CRISPR/Cas9 knockout of PDLIM2 results in increased levels of STAT2 following IFNα treatment, retention of STAT2 within the nucleus of HCV infected cells after IFNα stimulation, increased interferon response, and increased resistance to infection by several flaviviruses, indicating that PDLIM2 is a global regulator of the interferon response.

The response of cells to an invading pathogen must be swift and well controlled because of the detrimental effects of chronic inflammation. However, viruses often hijack host control mechanisms. HCV and flaviviruses are known to suppress the innate immune response in cells by a variety of mechanisms. This study clarifies and expands a specific cellular mechanism for global control of the antiviral response after the induction of interferon expression. It shows how several viruses hijack this control mechanism to suppress the innate interferon response.

IgG1 and IgG4 antibodies against Core and NS3 antigens of hepatitis C virus

INTRODUCTION

IgG subclasses involved in the immune response to hepatitis C virus (HCV) antigens have been rarely studied. We investigated the immune response mediated by IgG1 and IgG4 antibodies against the recombinant core and NS3 antigens in patients with chronic hepatitis C.

METHODS

Sixty patients infected with HCV genotype 1 without antiviral treatment and 60 healthy subjects participated in the study. Serum levels of alanine aminotransferase, HCV viremia, and the presence of cryoglobulinemia and liver fibrosis were determined. We investigated the serum IgG1 and IgG4 antibodies against recombinant HCV core and NS3 non-structural protein antigens using amplified indirect ELISA.

RESULTS

Anti-core and anti-NS3 IgG1 antibodies were detected in 33/60 (55%) and 46/60 (77%) patients, respectively, whereas only two healthy control samples reacted with an antigen (NS3). Anti-core IgG4 antibodies were not detected in either group, while 30/60 (50%) patients had anti-NS3 IgG4 antibodies. Even though there were higher levels of anti-NS3 IgG4 antibodies in patients with low viremia (< 8 × 105 IU/mL), IgG1 and IgG4 antibody levels did not correlate with ALT levels, the presence of cryoglobulinemia, or degree of hepatic fibrosis. High production of anti-core and anti-NS3 IgG1 antibodies was observed in chronic hepatitis C patients. In contrast, IgG4 antibodies seemed to only be produced against the NS3 non-structural antigen and appeared to be involved in viremia control.

CONCLUSIONS

IgG1 antibodies against structural and non-structural antigens can be detected in chronic hepatitis C, while IgG4 antibodies seem to be selectively stimulated by non-structural HCV proteins, such as the NS3 antigen.

Immunopathogenesis of Liver Injury During Hepatitis C Virus Infection

The present report describes current concepts about the mechanism of liver cell injury caused by host immune response against hepatitis C virus (HCV) infection in human beings. This report is based on the observations from experimental studies and follow-up actions on human liver diseases. The results from different investigations suggest that liver injury depends on the presentation of viral antigen and the level of host immune response raised against HCV-related peptides. Both innate and adaptive immunity are triggered to counter the viral onset. During development of host immunity, the cell-mediated immune response involving CD4⁺ Th1 cells and CD8⁺ cytotoxic T-lymphocyte (CTL) cells were found to play a major role in causing liver damage. The hepatic Innate lymphoid cells (ILCs) subsets are involved in the immune regulation of different liver diseases: viral hepatitis, mechanical liver injury, and fibrosis. Humoral immunity and natural killer (NK) cell action also contributed in liver cell injury by antibody-dependent cellular cytotoxicity (ADCC). In fact, immunopathogenesis of HCV infection is a complex phenomenon where regulation of immune response at several steps decides the possibility of viral elimination or persistence. Regulation of immune response was noted starting from viral-host interaction to immune reaction cascade engaged in cell damage. The activation or suppression of interferon-stimulated genes, NK cell action, CTL inducement by regulatory T cells (Treg), B cell proliferation, and so on was demonstrated during HCV infection. Involvement of HLA in antigen presentation, as well as types of viral genotypes, also influenced host immune response against HCV peptides. The combined effect of all these effector mechanisms ultimately decides the progression of viral onset to acute or chronic infection. In conclusion, immunopathogenesis of liver injury after HCV infection may be ascribed mainly to host immune response. Second, it is cell-mediated immunity that plays a predominant role in liver cell damage.

Association of HCV Infection with C-Reactive Protein: National Health and Nutrition Examination Survey (NHANES), 2009⁻2010

The relationship between hepatitis C virus (HCV) infection and C-reactive protein (CRP), which is an inflammatory biomarker, is limited in studies with the general population. It was hypothesized that changes in CRP levels are genotype-dependent in the general population with HCV infection. Thus, this study aimed to assess the prevalence of HCV infection and compare CRP levels with an anti-HCV antibody, HCV-RNA status, and HCV genotypes. A total of 5611 adult participants from the National and Health Nutrition Examination (NHANES), 2009⁻2010 survey were analyzed. Proc survey frequency, means, and multivariate regression were used due to the complex survey design of NHANES. The prevalence of HCV infection among the study population was 1.6%. There were lower mean CRP levels among people with anti-HCV antibody positive status compared to those with antibody negative status (0.12 ± 0.08 vs. 0.24 ± 0.02, p = 0.08, 95% Confidence Intervals, CI: -1.12 to 0.07). Mean CRP levels were also lower in people with HCV-RNA positive status compared to those with HCV-RNA negative status (0.56 ± 0.03 vs. 0.48 ± 0.05, p = 0.62 and 95% CI: -1.37 to 0.86). However, these differences were non-significant. With respect to HCV genotypes, significantly higher CRP levels were noted among people infected with HCV genotype 2 vs. genotype 1 (0.53 ± 0.06 vs. 0.23 ± 0.05, p < 0.01, 95% CI: -0.58 to -0.02) and those with HCV genotype 2 vs. HCV genotype 3 (0.53 ± 0.06, 0.28 ± 0.04, p < 0.01, 95% CI: 0.02 to 0.48). Further studies are needed to confirm this finding.

Association of serum levels of C-reactive protein with CRP-717 T/C polymorphism and viremia in HCV and HBV carriers

INTRODUCTION

The present study investigated the association of the rs2794521 polymorphism in the CRP gene in individuals with chronic hepatitis B and C, correlating it with markers of hepatic inflammation, fibrosis scores, viral load, and plasma protein levels.

METHODS

The study analyzed 185 blood samples obtained from patients with hepatitis B (n=74) and hepatitis C (n=111) and 300 samples from healthy donors. Genotyping was performed by real-time polymerase chain reaction, and protein levels were quantified using the automated immunoturbidimetric method.

RESULTS

The TT genotype was the most frequent in all studied groups and was associated with higher plasma levels of the protein but not with the progression of liver disease. Low levels of C-reactive protein were associated with increased viremia and scores indicative of severe fibrosis and cirrhosis.

CONCLUSIONS

The present results demonstrated a close relationship between the ability of the virus to replicate and cause liver damage and low serum concentrations of C-reactive protein. Future research may determine if these results can be interpreted as a possible form of escape for the virus by decreasing its action as an opsonin and decreasing phagocytosis, which are functions of C-reactive protein in the immune response.

Inflammasome Genes' Polymorphisms in Egyptian Chronic Hepatitis C Patients: Influence on Vulnerability to Infection and Response to Treatment

Chronic inflammation is a pivotal contributor to the liver damage mediated by hepatitis C virus (HCV). The NOD-like receptor, pyrin domain-containing 3 (NLRP3) inflammasome is activated by HCV in both hepatocytes and Kupffer cells. The aim of our study was to investigate the association of nine single-nucleotide polymorphisms in four inflammasome genes (NLRP3, CARD8, IL-1β, and IL-18) with the susceptibility to HCV infection and outcome of interferon treatment in 201 Egyptian chronic hepatitis C patients and 95 healthy controls. The genotyping was conducted using TaqMan predesigned SNP assay. In the comparative analysis, the CC genotype of the NLRP3 rs1539019 was found to be associated with the lower risk to chronic HCV infection (OR: 0.33, 95% CI: 0.17-0.62). This association was also found for the CA genotype and the A allele of the NLRP3 rs35829419 (OR: 0.18 and 0.22, respectively), in addition to the GG genotype and G allele of IL-18 rs1946518 (OR: 0.55 and 0.61, respectively). In contrast, the AA genotype of the IL-1β rs1143629 was significantly more frequent in HCV patients (OR: 1.7, 95% CI: 1-2.86). Notably, the frequency of the AA genotype of NLRP3 rs1539019 was significantly higher in patients with lack of response (NR) to the interferon treatment (OR: 1.95, 95% CI: 1-3.7). A similar association was found for both the CC genotype and C allele of the NLRP3 rs35829419 (OR: 2.78 and 2.73, respectively) and for the TT genotype and T allele of CARD8 rs2043211 (OR: 2.64 and 1.54, respectively). Yet, the IL-1β (rs1143629, rs1143634) and IL-18 (rs187238, rs1946518) polymorphisms did not show any significant association with response to interferon treatment. In conclusion, this study reports, for the first time, the association of genetic variations in NLRP3 with hepatitis C susceptibility and response to treatment in Egyptian patients. However, further large-scale studies are recommended to confirm our findings.

Interferon-α-induced retinopathy in chronic hepatitis C treatment: summary, considerations, and recommendations

Interferons are cytokines that regulate the host's response to viral infection, particularly in the setting of the immunologic response to the hepatitis C virus (HCV). While the virus has the ability to evade the host's innate and specific immunity, exogenous interferon-α with combined ribavirin, treatments have been found to achieve a significant sustained viral response in subgroups of patients with chronic HCV. One of the major side effects of interferon-α is an ocular retinopathy characterized by flame-shaped hemorrhages and cotton wool spots visualized on funduscopic examination. There have been documented cases of more severe side effects including optic nerve and retinal artery damage; however, these instances are the minority. We sought to investigate the literature surrounding interferon-induced retinopathy, clinically correlate our findings with two recent cases, and provide recommendations for practitioners who continue to manage chronic HCV patients using interferon-α with combined ribavirin treatments.

Increase of viral hemorrhagic septicemia virus growth by knockout of IRF9 gene in Epithelioma papulosum cyprini cells

Viral hemorrhagic septicemia virus (VHSV) has been a notorious pathogen in freshwater and marine fish. Due to the lack of effective treatment measures against VHSV disease, the development of prophylactic vaccines has been required, and methods that can produce high-titered viruses would be advantageous in producing cost-effective vaccines. Type I interferon (IFN) responses are the key elements of vertebrates' antiviral activities, and IFN-stimulated gene factor 3 (ISGF3) complex formed through type I IFNs up-regulates the expression of IFN-stimulated genes (ISGs). IFN regulatory factor 9 (IRF9) is a key component of ISGF3, so the inhibition of IRF9 would compromise host's type I IFN responses, which would weaken host antiviral activity. In this study, to increase the replication of VHSV, we generated IRF9 knockout Epithelioma papulosum cyprini (EPC) cells using a CRISPR/Cas9 vector that contains an EPC cell's U6 promoter-driven guide RNA cassette (targeting IRF9 gene) and a Cas9 expressing cassette. In the clones of IRF9 knockout EPC cells, there were no increase in ISG15 gene by poly I:C, and in Mx1 gene by both poly I:C and VHSV. Interestingly, although the increased folds were conspicuously lower than control EPC cells, the expression of ISG 15 gene in all the IRF9 knockout clones was significantly increased by VHSV infection. Control EPC cells pre-treated with poly I:C did not show any CPE when infected with VHSV, however, IRF9 knockout EPC cells showed CPE by VHSV infection in spite of being pretreated with poly I:C. The replication of VHSV in IRF9 knockout EPC cells was significantly faster and higher than that in control EPC cells indicating that the IRF9 knockout-mediated decrease of type I IFN responses allowed VHSV to replicate efficiently. Considering an economical aspect for the production of fish vaccines, the present IRF9 knockout EPC cells can be used to get higher-titered VHSV.

Restoration of natural killer cell activity by interferon-free direct-acting antiviral combination therapy in chronic hepatitis C patients

AIM

Interferon-free direct-acting antiviral (DAA) therapy is an effective treatment for chronic hepatitis C (CH(C)) patients. Activity of natural killer (NK) cells was reported to be impaired in patients with hepatitis C virus infection. The aim of this study was to examine whether DAA therapy could restore NK activity in patients with CH(C).

METHODS

Direct-acting antiviral therapy was given to 31 CH(C) patients as asunaprevir/daclatasvir (ASV/DCV) (n = 15), ledipasvir/sofosbuvir (n = 7), ombitasvir/paritaprevir/ritonavir (n = 6), or elbasvir/grazoprevir (n = 3). Prior to therapy (0M), at the completion of the therapy (EOT), and at 24 weeks after completion (AFTER), NK activity and the frequency of CD56^dim NK and CD56^bright NK cells in peripheral blood were estimated by Cr release assay and flow cytometry. Statistical analysis was carried out by anova and the Mann-Whitney U-test.

RESULTS

In one of the ASV/DCV-treated patients, treatment was stopped 12 weeks after initiation of therapy because of viral breakthrough. The anova showed that NK activity significantly improved at EOT (vs. 0M, P < 0.01) and at AFTER (vs. 0M, P < 0.001) in 30 patients with sustained virologic response. It also showed that the frequency of CD56^dim NK cells was significantly increased at EOT and at AFTER (vs. 0M, P < 0.05). In addition, the NK activity ratio (AFTER/0M) had no significant difference between patient groups with higher and lower Fibrosis-4 scores.

CONCLUSION

Direct-acting antiviral therapy in CH(C) patients could improve NK activity by increasing the frequency of CD56^dim NK cells. Additionally, our results might imply that DAAs therapy could reduce the risk of hepatocarcinogenesis by restoring innate immune responses.

Interferon gamma and interleukin 8 gene polymorphisms in patients with hepatitis C virus related oral lichen planus

OBJECTIVES

This study aimed to determine the association of rs2430561 and rs4073 polymorphisms in the Interferon gamma (IFN-ɤ) and Interleukin 8 (IL-8) genes, respectively, with hepatitis C virus-related oral lichen planus and disease severity.

DESIGN

This is a case-control study. 60 subjects were equally divided into patients with and without oral lichen planus. They were further subdivided into hepatitis C virus seropositive and seronegative patients. All patients were genotyped for IFN-γ rs2430561 thymine to adenine (T > A) and IL-8 rs4073 adenine to thymine (A > T) polymorphisms. All patients with oral lichen planus had their lesions measured and documented using the Escudier scoring system.

RESULTS

Disease activity was significantly higher in the "oral lichen planus/hepatitis C virus-positive" patients than in the "oral lichen planus/hepatitis C virus-negative" patients (P = 0.003). IFN-γ rs2430561 T > A and IL-8 rs4073 A > T genotypes and allele frequencies were not associated with the oral lichen planus group or the normal group. Stratification of the two groups into HCV and non-HCV-infected patients or into erosive and non-erosive types revealed no significant associations. The "A-allele-containing" genotypes of IL-8 rs4073 A > T were significantly more prevalent in the patients with oral lichen planus than in those without.

CONCLUSION

Hepatitis C virus infection is associated with the development of erosive oral lichen planus. The A-allele of IL-8 rs4073 A > T may have a role in the development and progression of oral lichen planus.

Aminoacyl-tRNA synthetases, therapeutic targets for infectious diseases

Despite remarkable advances in medical science, infection-associated diseases remain among the leading causes of death worldwide. There is a great deal of interest and concern at the rate at which new pathogens are emerging and causing significant human health problems. Expanding our understanding of how cells regulate signaling networks to defend against invaders and retain cell homeostasis will reveal promising strategies against infection. It has taken scientists decades to appreciate that eukaryotic aminoacyl-tRNA synthetases (ARSs) play a role as global cell signaling mediators to regulate cell homeostasis, beyond their intrinsic function as protein synthesis enzymes. Recent discoveries revealed that ubiquitously expressed standby cytoplasmic ARSs sense and respond to danger signals and regulate immunity against infections, indicating their potential as therapeutic targets for infectious diseases. In this review, we discuss ARS-mediated anti-infectious signaling and the emerging role of ARSs in antimicrobial immunity. In contrast to their ability to defend against infection, host ARSs are inevitably co-opted by viruses for survival and propagation. We therefore provide a brief overview of the communication between viruses and the ARS system. Finally, we discuss encouraging new approaches to develop ARSs as therapeutics for infectious diseases.

Regulation of interferon signaling and HCV‑RNA replication by extracellular matrix

Although interferon (IFN)‑based treatment of patients with chronic hepatitis C virus (HCV) infection is widely applied, treatment resistance is often observed in patients with advanced liver fibrosis. Given that the molecular mechanisms of IFN resistance in liver fibrosis remain elusive, the present study investigated the effects of extracellular matrix (ECM) on IFN signaling in hepatic cells. The native HuH‑7 human hepatoma cell line and HuH‑7 cells were stably transfected with full‑length HCV‑RNA fused with Renilla luciferase (OR6 cells) were cultured on ECM‑coated dishes or non‑coated plastic dishes (NDs), and treated with human IFN‑α. In Huh‑7 cells cultured on coated dishes, the IFN‑stimulated response element (ISRE) luciferase activity was measured following ISRE plasmid transfection and the expression of IFN‑stimulated genes (ISG) were significantly lower than those in cells cultured on NDs. In addition, after IFN‑α treatment, the amount of HCV‑RNA and viral protein produced by OR6 cells cultured on coated dishes was higher than that produced by cells cultured on NDs. When cells were treated with β1‑integrin‑blocking antibody to disrupt the cell‑matrix interaction, the ISRE luciferase activity was restored, and the protein expression of ISG was increased, while that of HCV proteins was suppressed. Treatment of cells with integrin‑linked kinase (ILK) inhibitor or focal adhesion kinase (FAK) inhibitor restored the ISRE luciferase activity and expression of ISG proteins. These results suggested that β1‑integrin‑mediated signals affected the IFN signaling and promoted HCV replication. Therefore, the accumulation of ECM in liver fibrosis may impair IFN signaling through β1‑integrin‑mediated signaling involving ILK and FAK.

The antiviral role of zinc and metallothioneins in hepatitis C infection

Metallothioneins (MTs) are small, cysteine-rich proteins characterized by a high affinity for monovalent and divalent cations, such as copper and zinc. Of the four known MT isoforms, only, members of the MT 1 and 2 subfamilies are widely expressed, acting as metal chaperones whose primary role is to mediate intracellular zinc homoeostasis. Metallothioneins are potently induced by heavy metals and other sources of oxidative stress where they facilitate metal binding and detoxification as well as free radical scavenging. Metallothionein expression is well documented in the context of viral infection; however, it remains uncertain whether MTs possess specific antiviral roles or whether induction is merely a consequence of cellular stress. To better understand the role of MTs following hepatitis C virus (HCV) infection, we examined MT expression and localization in vitro and in vivo and used a siRNA knockdown approach to ascertain their antiviral efficacy. We confirmed HCV-driven MT induction in vitro and demonstrated MT accumulation in the nucleus of HCV-infected hepatocytes by immunofluorescence. Using a pan-MT siRNA to knock down all members of the MT1 and MT2 subfamilies, we demonstrate that they are mildly antiviral against the JFH1 strain of HCV in vitro (~1.4 fold increase in viral RNA, P < .05). Furthermore, the antiviral effect of zinc treatment against HCV in vitro was mediated through MT induction (P < .05). Our data suggest a potential benefit of using zinc as a low-cost adjunct to current HCV antiviral therapies and suggest that zinc may facilitate the antiviral role of MTs against other viruses.

Opposite Effects of Two Human ATG10 Isoforms on Replication of a HCV Sub-genomic Replicon Are Mediated via Regulating Autophagy Flux in Zebrafish

Autophagy is a host mechanism for cellular homeostatic control. Intracellular stresses are symptoms of, and responses to, dysregulation of the physiological environment of the cell. Alternative gene transcription splicing is a mechanism potentially used by a host to respond to physiological or pathological challenges. Here, we aimed to confirm opposite effects of two isoforms of the human autophagy-related protein ATG10 on an HCV subgenomic replicon in zebrafish. A liver-specific HCV subreplicon model was established and exhibited several changes in gene expression typically induced by HCV infection, including overexpression of several HCV-dependent genes (argsyn, leugpcr, rasgbd, and scaf-2), as well as overexpression of several ER stress related genes (atf4, chop, atf6, and bip). Autophagy flux was blocked in the HCV model. Our results indicated that the replication of the HCV subreplicon was suppressed via a decrease in autophagosome formation caused by the autophagy inhibitor 3MA, but enhanced via dysfunction in the lysosomal degradation caused by another autophagy inhibitor CQ. Human ATG10, a canonical isoform in autophagy, facilitated the amplification of the HCV-subgenomic replicon via promoting autophagosome formation. ATG10S, a non-canonical short isoform of the ATG10 protein, promoted autophagy flux, leading to lysosomal degradation of the HCV-subgenomic replicon. Human ATG10S may therefore inhibit HCV replication, and may be an appropriate target for future antiviral drug screening.

Hepatitis C virus core impacts expression of miR122 and miR204 involved in carcinogenic progression via regulation of TGFBRAP1 and HOTTIP expression

Background

Despite the breadth of understanding the noncoding RNAs' function in molecular biology, their functional roles in hepatocellular carcinoma (HCC) is poorly understood. In this study, we investigated the effect of hepatitis C virus (HCV) core upon the expression of noncoding RNAs.

Methods

The lncRNAs, mRNAs, and circRNAs were employed for identification of HCV core protein gene expression in human Huh7 hepatoma (Huh7) cell line. In data analysis, we applied a threshold that eliminated all genes that were not increased or decreased by at least a 2-fold change in a comparison between transfected and control cells. Hierarchical Clustering and the Kyoto encyclopedia of genes and genome pathway analyses were performed to show the distinguishable lncRNA, mRNAs, and circRNAs expression pattern among samples.

Results

The array data showed that 4,851 lncRNAs, 4,785 mRNAs, and 823 circRNAs were 2-fold up-regulated but 3,569 lncRNAs, 3,192 mRNAs, and 419 circRNAs were 2-fold down-regulated in Huh 7-core cells. The genes in the enriched set were associated with macromolecule and nucleic acid metabolic processes, DNA damage response and regulation of voltage-gated calcium channel. We identified 10 genes from the selected 14 genes that were higher or lower expression in Huh7-core cells than that of Huh7-vector cells by quantitative real-time polymerase chain reaction. Interestingly, overexpression of miR122 and miR204 partly abrogated the expression of TGFBRAP1 and HOTTIP, and increased the HPCAL1 expression in the predicted carcinogenic pathways.

Conclusion

Our data suggests that the pathways of miR204-HPCAL1-lncRNAHOTTIP and miR122-TGFBRAP1 were likely involved in the carcinogenic progress due to the presence of HCV core, and that overexpression of miR122 and miR204 might inhibit the HCC progress by down-regulation of TGFBRAP1 and HOTTIP expression.

Myxovirus resistance protein A inhibits hepatitis C virus replication through JAK-STAT pathway activation

The interferon-inducible dynamin-like GTPase myxovirus resistance protein A (MxA) exhibits activity against multiple viruses. However, its role in the life cycle of hepatitis C virus (HCV) is unclear, and the mechanisms underlying the anti-HCV activity of MxA require further investigation. In this study, we demonstrated that exogenous MxA expression in the Huh7 and Huh7.5.1 hepatoma cell lines significantly decreased the levels of HCV RNA and core proteins, whereas MxA knockdown exerted the opposite effect. MxA-mediated inhibition of HCV replication was found to involve the JAK-STAT pathway: STAT1 phosphorylation and the expression of IFN-stimulated genes (ISGs) such as guanylate-binding protein 1 and 2'-5'-oligoadenylate synthetase 1 were augmented by MxA overexpression and reduced by endogenous MxA silencing. Treatment with the JAK inhibitor ruxolitinib abrogated the MxA-mediated suppression of HCV replication and activation of the JAK-STAT pathway. Additionally, transfection with an MxA mutant with disrupted GTP-binding consensus motifs abrogated activation of the JAK-STAT pathway and resistance to HCV replication. This study shows that MxA inhibits HCV replication by activating the JAK-STAT signaling pathway through a mechanism involving its GTPase function.

Immune response of Th17-associated cytokines by peripheral blood mononuclear cells from patients with chronic hepatitis C virus infection

Hepatitis C virus (HCV) chronic infection causes severe cellular immune dysfunction. Here, we investigated the production of Th17-associated cytokines by peripheral blood mononuclear cells (PBMCs) of untreated patients with HCV, patients presenting an early virologic response (EVR) after 12weeks of treatment with interferon-α plus ribavirin with or without HCV protease inhibitors, and patients who were nonresponders to HCV therapy. PBMCs were stimulated with HCV core and nonstructural antigens, and the production of Th17-associated cytokines was measured with a Milliplex MAP immunoassay. Core-stimulated PBMCs from both untreated and nonresponder patients produced interleukin (IL)-17A, and vigorous production of IL-17A in response to NS3 antigen was only verified in the untreated group. Nonresponder patients also produced IL-17F after core antigen stimulation. IL-21 production was unaltered in the three groups of patients, whereas IL-17E and IL-22 were not detected. The production of Th17 cytokines by cells from patients showing an EVR was insignificant. IL-17A and IL-17F levels were not correlated with alanine aminotransferase levels or viremia. However, advanced fibrosis was associated with higher IL-17A production in T0 cells stimulated with core antigen. Untreated patients with HCV and patients who were nonresponders to antiviral treatment differed in their PBMC immune responses of Th17-associated cytokines. The early virological response to antiviral treatment dramatically decreased Th17 immune responses to HCV antigens.

Interleukin-6: A promising cytokine to support liver regeneration and adaptive immunity in liver pathologies

Liver pathologies (fibrosis, cirrhosis, alcoholic, non-alcoholic diseases and hepatocellular carcinoma) represent one of the most common causes of death worldwide. A number of genetic and environmental factors contribute to the development of liver diseases. Interleukin-6 (IL-6) is a pleiotropic cytokine, exerting variety of effects on inflammation, liver regeneration, and defence against infections by regulating adaptive immunity. Due to its high abundance in inflammatory settings, IL-6 is often viewed as a detrimental cytokine. However, accumulating evidence supports the view that IL-6 has a beneficial impact in numerous liver pathologies, due to its roles in liver regeneration and in promoting an anti-inflammatory response in certain conditions. IL-6 promotes proliferation, angiogenesis and metabolism, and downregulates apoptosis and oxidative stress; together these functions are critical for mediating hepatoprotection. IL-6 is also an important regulator of adaptive immunity where it induces T cell differentiation and regulates autoimmunity. It can augment antiviral adaptive immune responses and mitigate exhaustion of T cells during chronic infection. This review focuses on studies that present IL-6 as a key factor in regulating liver regeneration and in supporting effector immune functions and suggests that these functions of IL-6 can be exploited in treatment strategies for liver pathologies.

Suppression of interferon-mediated anti-HBV response by single CpG methylation in the 5'-UTR of TRIM22

OBJECTIVE

Interferons (IFNs) mediate direct antiviral activity. They play a crucial role in the early host immune response against viral infections. However, IFN therapy for HBV infection is less effective than for other viral infections.

DESIGN

We explored the cellular targets of HBV in response to IFNs using proteome-wide screening.

RESULTS

Using LC-MS/MS, we identified proteins downregulated and upregulated by IFN treatment in HBV X protein (HBx)-stable and control cells. We found several IFN-stimulated genes downregulated by HBx, including TRIM22, which is known as an antiretroviral protein. We demonstrated that HBx suppresses the transcription of TRIM22 through a single CpG methylation in its 5'-UTR, which further reduces the IFN regulatory factor-1 binding affinity, thereby suppressing the IFN-stimulated induction of TRIM22.

CONCLUSIONS

We verified our findings using a mouse model, primary human hepatocytes and human liver tissues. Our data elucidate a mechanism by which HBV evades the host innate immune system.

Role of TLRs and IL-6 in the outcome of chronic hepatitis C treatment in Tunisian population

OBJECTIVES

TLRs are one of the most studied families of pathogen recognition receptors (PRRs) and play a pivotal role during HCV infection. The binding of ligands to TLRs on antigen presenting cells (APCs) leads to secretion of inflammatory cytokines, such as IL6, and induction of the acquired immunity response. Therefore, it has become necessarily to harness the TLRs properties' on therapeutically tools to enhance the HCV treatment response. Herein, we investigated the association between TLR3, TLR4 variants and nine IL-6 polymorphisms, and response to anti-viral treatment during HCV infection.

METHODS

Study subjects comprised 120 patients infected with HCV-1b and treated with Peg-IFN/RBV. Genotyping of nine IL-6 variants were done by real -time PCR and genotyping of TLRs polymorphisms were done by RFLP-PCR.

RESULTS

High frequency of TLR3 rs3775290 C/C genotype and TLR4 rs4986790 A/A genotype were noticed among patients with sustained viral response compared to Non-responder patients. The genetic association of TLR3 and TLR4 variants was evidenced by the improvement in the kinetics of viral load decline, with superiority of TLR3 compared to TLR4. Among, nine polymorphisms studied on IL-6 only rs1800796, rs2069845 and rs1880242 were associated with sustained viral response. Our study reports also that the common favourable IL-28B variant is essential for TLR-activated antiviral protection.

CONCLUSION

TLR3 and TLR4 are involved in the pathogenesis of viral infections. TLR3 may be better suited than TLR4 to activate anti-viral program. Moreover, we propose that the Th2 cytokine, IL-6, constitutes a determinant of the outcome of therapy in HCV patients.

Viral deubiquitinases: role in evasion of anti-viral innate immunity

Host anti-viral innate-immune signalling pathways are regulated by a variety of post-translation modifications including ubiquitination, which is critical to regulate various signalling pathways for synthesis of anti-viral molecules. A homeostasis of host immune responses, induced due to viral infection and further ubiquitination, is maintained by the action of deubiquitinases (DUB). Infecting viruses utilize the process of deubiquitination for tricking host immune system wherein viral DUBs compete with host DUBs for inhibition of innate-immune anti-viral signalling pathways, which instead of maintaining an immune homeostasis bring about virus-mediated pathogenesis. This suggests that viruses co-evolve with their hosts to acquire similar machinery for tricking immune surveillance and establishing infection.

(-)-Epigallocatechin-3-gallate enhances poly I:C-induced interferon-λ1 production and inhibits hepatitis C virus replication in hepatocytes

AIM

To investigate the effect of (-)-epigallocatechin-3-gallate (EGCG) on polyinosinic-polycytidylic acid (poly I:C)-triggered intracellular innate immunity against hepatitis C virus (HCV) in hepatocytes.

METHODS

A cell culture model of HCV infection was generated by infecting a hepatoma cell line, Huh7, with HCV JFH-1 strain (JFH-1-Huh7). Poly I:C with a high molecular weight and EGCG were used to stimulate the JFH-1-Huh7 cells. Real-time reverse transcription-polymerase chain reaction was used to detect the expression levels of intracellular mRNAs and of intracellular and extracellular HCV RNA. Enzyme-linked immunosorbent assay was used to evaluate the interferon (IFN)-λ1 protein level in the cell culture supernatant. Immunostaining was used to examine HCV core protein expression in Huh7 cells.

RESULTS

Our recent study showed that HCV replication could impair poly I:C-triggered intracellular innate immune responses in hepatocytes. In the current study, we showed that EGCG treatment significantly increased the poly I:C-induced expression of Toll-like receptor 3 (TLR3), retinoic acid-inducible gene I, and IFN-λ1 in JFH-1-Huh7 cells. In addition, supplementation with EGCG increased the poly I:C-mediated antiviral activity in JFH-1-Huh7 cells at the intracellular and extracellular HCV RNA and protein levels. Further investigation of the mechanisms showed that EGCG treatment significantly enhanced the poly I:C-induced expression of IFN-regulatory factor 9 and several antiviral IFN-stimulated genes, including ISG15, ISG56, myxovirus resistance A, and 2'-5'-oligoadenylate synthetase 1, which encode the key antiviral elements in the IFN signaling pathway.

CONCLUSION

Our observations provide experimental evidence that EGCG has the ability to enhance poly I:C-induced intracellular antiviral innate immunity against HCV replication in hepatocytes.

Immunogenetic studies of the hepatitis C virus infection in an era of pan-genotype antiviral therapies - Effective treatment is coming

What are the factors that influence human hepatitis C virus (HCV) infection, hepatitis status establishment, and disease progression? Firstly, one has to consider the genetic background of the host and HCV genotypes. The immunogenetic host profile will reflect how each infected individual deals with infection. Secondly, there are environmental factors that drive susceptibility or resistance to certain viral strains. These will dictate (I) the susceptibility to infection; (II) whether or not an infected person will promote viral clearance; (III) the immune response and the response profile to therapy; and (IV) whether and how long it would take to the development of HCV-associated diseases, as well as their severity. Looking at this scenario, this review addresses clinical aspects of HCV infection, following by an update of molecular and cellular features of the immune response against the virus. The evasion mechanisms used by HCV are presented, considering the potential role of exosomes in infection. Genetic factors influencing HCV infection and pathogenesis are the main topics of the article. Shortly, HLAs, MBLs, TLRs, ILs, and IFNLs genes have relevant roles in the susceptibility to HCV infection. In addition, ILs, IFNLs, as well as TLRs genes are important modulators of HCV-associated diseases. The viral aspects that influence HCV infection are presented, followed by a discussion about evolutionary aspects of host and HCV interaction. HCV and HIV infections are close related. Thus, we also present a discussion about HIV/HCV co-infection, focusing on cellular and molecular aspects of this interaction. Pharmacogenetics and treatment of HCV infection are the last topics of this review. The understanding of how the host genetics interacts with viral and environmental factors is crucial for the development of new strategies to prevent HCV infection, even in an era of potential development of pan-genotypic antivirals.

Real-world challenges for hepatitis C virus medications: a critical overview

From 2010, the landscape of hepatitis C therapeutics has been changed rapidly, and today we are standing at a cusp of a pharmacological revolution where highly effective and interferon (IFN)-free direct acting antivirals (DAAs) are already on the market. Such treatment paradigms attain 90-95% sustained virologic response (SVR; undetectable viral load at week 12 or 24 at the end of therapy) rates in treated individuals compared to 50-70% with treatment completion of dual-therapy-pegylated interferon (PEG-IFN) and ribavirin (RBV). As the major goal now for the hepatologists, clinicians, physicians, and health care workers is likely to eradicate hepatitis C infection in parallel to treatment, the demand is for a one-size-fits-all pill that could be prescribed beyond the limitations of hepatitis C genotype, viral load, previous treatment history, advanced hepatic manifestations (fibrosis, cirrhosis) and antiviral drug resistance. Although the new treatment strategies have shown high cure rates in clinical trials, such treatment paradigms are posing dilemmas too in real-world clinical practice. Therapy cost, treatment access to low and middle-income countries, treatment-emergent adverse events, lack of effective viral screening and disease progression simulation models are potential challenges in this prospect. This review article deeply overviews the challenges encountered while surmounting the burden of hepatitis C around the world.

GRIM-19 Restricts HCV Replication by Attenuating Intracellular Lipid Accumulation

Gene-associated with retinoid-interferon-induced mortality 19 (GRIM-19) targets multiple signaling pathways involved in cell death and growth. However, the role of GRIM-19 in the pathogenesis of hepatitis virus infections remains unexplored. Here, we investigated the restrictive effects of GRIM-19 on the replication of hepatitis C virus (HCV). We found that GRIM-19 protein levels were reduced in HCV-infected Huh7 cells and Huh7 cells harboring HCV replicons. Moreover, ectopically expressed GRIM-19 caused a reduction in both intracellular viral RNA levels and secreted viruses in HCVcc-infected cell cultures. The restrictive effect on HCV replication was restored by treatment with siRNA against GRIM-19. Interestingly, GRIM-19 overexpression did not alter the level of phosphorylated STAT3 or its subcellular distribution. Strikingly, forced expression of GRIM-19 attenuated an increase in intracellular lipid droplets after oleic acid (OA) treatment or HCVcc infection. GRIM-19 overexpression abrogated fatty acid-induced upregulation of sterol regulatory element-binding transcription factor-1 (SREBP-1c), resulting in attenuated expression of its target genes such as fatty acid synthase (FAS) and acetyl CoA carboxylase (ACC). Treatment with OA or overexpression of SREBP-1c in GRIM-19-expressing, HCVcc-infected cells restored HCV replication. Our results suggest that GRIM-19 interferes with HCV replication by attenuating intracellular lipid accumulation and therefore is an anti-viral host factor that could be a promising target for HCV treatment.

E3 ligase FBXW7 is critical for RIG-I stabilization during antiviral responses

Viruses can escape from host recognition by degradation of RIG-I or interference with the RIG-I signalling to establish persistent infections. However, the mechanisms by which host cells stabilize RIG-I protein for avoiding its degradation are largely unknown. We report here that, upon virus infection, the E3 ubiquitin ligase FBXW7 translocates from the nucleus into the cytoplasm and stabilizes RIG-I. FBXW7 interacts with SHP2 and mediates the degradation and ubiquitination of SHP2, thus disrupting the SHP2/c-Cbl complex, which mediates RIG-I degradation. When infected with VSV or influenza A virus, FBXW7 conditional knockout mice (Lysm⁺FBXW7^f/f) show impaired antiviral immunity. FBXW7-deficient macrophages have decreased RIG-I protein levels and type-I interferon signalling. Furthermore, PBMCs from RSV-infected children have reduced FBXW7 mRNA levels. Our results identify FBXW7 as an important interacting partner for RIG-I. These findings provide insights into the function of FBXW7 in antiviral immunity and its related clinical significance.

The innate immune response to many RNA viruses depends on recognition of viral RNA by RIG-I. Here the authors show that, upon virus infection, FBXW7 interacts with RIG-I and inhibits ubiquitin-mediated degradation of RIG-I, resulting in increased interferon signalling in vitro and in vivo.

Impact of Viral Etiology on Postoperative De Novo Recurrence After Hepatectomy for Hepatocellular Carcinoma in Cirrhotic Patients

BACKGROUND AND AIM

Liver cirrhosis (LC) and hepatocellular carcinoma (HCC) are associated with viral hepatitis, especially hepatitis B virus (HBV) and hepatitis C virus (HCV). Whether differences exist in postoperative de novo carcinogenesis from established cirrhosis according to viral etiology remains unclear.

METHODS

Data from 313 LC patients with viral hepatitis (HBV-LC, n = 108 and HCV-LC, n = 205) who underwent curative-intent hepatectomy for HCC were retrospectively collected. Clinicopathological characteristics, cumulative recurrence, chronological change of recurrence rate, and predictors of recurrence were analyzed.

RESULTS

Baseline patient characteristics were different among patients with HBV versus HCV as HCC-LC patients had a lower albumin, higher alanine transaminase, and higher incidence of tumor multicentricity (all P < 0.050). The 1-, 3-, and 5-year cumulative recurrence was 16.7, 38.6, and 53.7% in HBV-LC versus 20.8, 52.2, and 71.6% in HCV-LC (P = 0.002) patients, respectively. The postoperative annual recurrence rates of HCV-LC were consistently higher than that of HBV-LC patients. After matching on clinicopathologic characteristics, while recurrence was comparable in the early time period, HCV-LC patients had a 2-5% higher incidence of recurrence compared with HBV-LC patients after 20 months post-resection. On multivariable analysis, HCV infection was an independent predictor of recurrence (HR 1.55; 95% CI 1.13-2.13).

CONCLUSION

HCV-related LC was associated with a higher postoperative de novo carcinogenesis than HBV-related LC. Establishment of different treatment algorithms as well as follow-up surveillance protocols stratified by viral etiology may be warranted.