Infection of primary human macrophages with hepatitis C virus in vitro: induction of tumour necrosis factor-alpha and interleukin 8

Depression and Cognitive Dysfunction in Patients with Chronic Hepatitis C: Correlation with Viral Replication in the Peripheral Blood Mononuclear Cells and Cytokines in Serum

Chronic hepatitis C virus (HCV) infection is commonly associated with depression and cognitive dysfunction, the cause of which could be related to the HCV neuroinvasion and/or state of chronic inflammation. Viral sequences and proteins were previously detected in the brain and since blood leukocytes can cross the blood-brain barrier, they could provide viral access to the CNS. Eighty chronic hepatitis C patients were tested for viral replication in PBMCs (detection of the HCV RNA-negative strand) and serum cytokines. Depression was assessed by the Beck Depression Inventory (BDI), neuroticism by the Eysenck Personality Inventory (N/EPO-R), and anxiety by the State-Trait Anxiety Inventory (STAI) while neurocognitive testing included the Wisconsin Card Sorting Test (WCST), Ruff Figural Fluency Test (RFFT), California Verbal Learning Test (CVLT), and Grooved Pegboard Test (GPT). The HCV RNA-negative strand was detected in PBMCs from 24 (30%) patients and these patients had significantly higher BDI scores (median 12.5 [IQR] 6.3-20.5 vs. median 8.00 [IQR] 3-12; p = 0.013). Both depression and anxiety correlated positively with IL-8 while cognitive flexibility, executive function, problem-solving skills, memory, and motor functioning correlated negatively with some proinflammatory cytokines. Our findings suggest that due to chronic HCV infection, the brain function is negatively affected by both viral replication in PBMCs and by the immune activation state.

Modulation of Production of Th1/Th2 Cytokines in Peripheral Blood Mononuclear Cells and Neutrophils by Hepatitis C Virus Infection in Chronically Infected Patients

This study investigated the influence of Hepatitis C virus (HCV) infection on the cytokine production profiles of the peripheral blood monoculear cells (PBMC) and neutrophils in chronically naïve HCV-infected patients. Seventy-five genotype-4 naïve HCV-infected patients (HCV+) and healthy subjects (HCV-) were enrolled. The neutrophils and the PBMC were separated by density gradient sedimentation and stimulated with a mitogen. The culture supernatants were evaluated for levels of IFN-α, IFN-γ, IL-2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-12, and TNF-α using anti-cytokine antibody MACSPlex capture beads. The PBMC cytokine profiles of HCV+ patients showed significantly lower mean values for IFN-γ, IL-2, IL-6, IL-9, and IL-10 (p < 0.0001) as compared to HCV- subjects. In contrast, HCV+ patients showed higher mean levels of PBMC cytokine values for IL-5 and TNF-α (p < 0.0001). As for neutrophils, HCV+ patients showed significantly lower mean levels of IFN-α, IFN-γ, IL-2, IL-4, IL-6, IL-9, and IL-10 (p < 0.0001). In contrast, the neutrophils from HCV+ patients showed higher mean levels of IL-5, IL-12, and TNF-α (p < 0.0001). Th1-Th2 cytokine ratios suggested a lower Th1 bias in HCV+ subjects as compared to HCV- subjects. Our results suggest that chronic HCV infection brings about an immunomodulatory effect not only on neutrophils, but also to a lower extent on PBMCs.

Hepatitis C Virus Entry into Macrophages/Monocytes Mainly Depends on the Phagocytosis of Macrophages

BACKGROUND

Hepatitis C virus (HCV) has been classified as a strictly hepatotropic pathogen for a long time, and hepatocytes are target cells for HCV infection. More and more studies showed non-liver cells supported HCV entry and replication, such as macrophages. The mechanisms of HCV entry into macrophages are still not clear.

AIMS

This study aims to determine the way of HCV entry into macrophages.

METHODS

Cell culture-derived infectious HCV particles (HCVcc) were prepared using Huh7 cells transfected with HCV RNA. CD81-knockdown cells were obtained through siRNA transfection. HCV RNA levels were determined by RT-qPCR. Flow cytometry analyses were used to determine cell surface levels of CD11b, CD68, and CD81. ELISA and western blotting were performed to quantify the protein levels of IL-1β, IL-6, and TNF-α. Phagocytic ability was determined by neutral red uptake assay.

RESULTS

CD81 knockdown could not inhibit HCVcc entry into macrophages. The entry of HCV into macrophages could not be blocked by pooled IgG from chronic hepatitis C patient's sera. Macrophages derived from THP-1 cells displayed stronger phagocytic capacity, which also swallowed more HCV RNA. Treatment of macrophages with endocytic inhibitor, methyl-β-cyclodextrin, decreased the internalization of HCV. HCV uptake by macrophages was related to the reorganization of F-actin cytoskeleton and PI3Ks activation. HCV infection significantly increased the expression of IL1β and IL6 in macrophages and promoted apoptosis of macrophages.

CONCLUSIONS

HCV entry into macrophages mainly depends on phagocytosis of macrophages.

Monocyte chemoattractant protein 1 released from macrophages induced by hepatitis C virus promotes monocytes migration

Hepatitis C Virus (HCV) infection usually progress to chronic liver disease and shows a significant increase in total monocyte/macrophages numbers in the liver. Monocyte chemoattractant protein-1 (MCP-1) plays a role in the recruitment of monocytes to the liver. In this study we found that MCP-1 were up-regulated in macrophages cultured with cell-culture derived infectious HCV particles (HCVcc) and promoted the migration of monocytes. IL1β, IL6 and TNFα were factors that induced MCP-1 expression, which were up-regulated in macrophages induced by HCV. Long-term of HCV incubation induced apoptosis of macrophages. Finally, we observed the effect of HCV infected macrophages on nearby liver cells. Huh7 cells continuously co-cultured with monocyte/macrophages displayed increased expression of pro-inflammatory cytokines and the morphology of Huh7 cells were greatly changed. Taken together, our study provides more information for the role of monocyte/macrophages in HCV related chronic liver disease.

Neurologic Manifestations of Hepatitis C Virus Infection

The extrahepatic manifestations of hepatitis C include effects on the central nervous system, which have been associated with the ability of hepatitis C virus (HCV) to replicate in microglial and endothelial cells and the chronic inflammation induced by HCV. HCV can induce impaired neurocognition, which is clinically manifested by impaired quality of life, fatigue, and brain fog. These cognitive defects can be present even in patients with mild histologic HCV and have been confirmed by neurocognitive testing and brain imaging by magnetic resonance spectroscopy. Neurocognitive defects include loss of functioning memory and subtle changes in attention and processing speed.

Systematic review and meta-analysis of hepatitis C virus infection and HIV viral load: new insights into epidemiologic synergy

INTRODUCTION

Hepatitis C virus (HCV) and HIV infection frequently co-occur due to shared transmission routes. Co-infection is associated with higher HCV viral load (VL), but less is known about the effect of HCV infection on HIV VL and risk of onward transmission.

METHODS

We undertook a systematic review comparing 1) HIV VL among ART-naïve, HCV co-infected individuals versus HIV mono-infected individuals and 2) HIV VL among treated versus untreated HCV co-infected individuals. We performed a random-effects meta-analysis and quantified heterogeneity using the I(2) statistic. We followed Cochrane Collaboration guidelines in conducting our review and PRISMA guidelines in reporting results.

RESULTS AND DISCUSSION

We screened 3925 articles and identified 17 relevant publications. A meta-analysis found no evidence of increased HIV VL associated with HCV co-infection or between HIV VL and HCV treatment with pegylated interferon-alpha-2a/b and ribavirin.

CONCLUSIONS

This finding is in contrast to the substantial increases in HIV VL observed with several other systemic infections. It presents opportunities to elucidate the biological pathways that underpin epidemiological synergy in HIV co-infections and may enable prediction of which co-infections are most important to epidemic control.

Alterations in the iron homeostasis network: A driving force for macrophage-mediated hepatitis C virus persistency

Mechanisms that favor Hepatitis C virus (HCV) persistence over clearance are unclear, but involve defective innate immunity. Chronic infection is characterized by hepatic iron overload, hyperferraemia and hyperferittinaemia. Hepcidin modulates iron egress via ferroportin and its storage in ferritin. Chronic HCV patients have decreased hepcidin, while HCV replication is modified by HAMP silencing. We aimed to investigate interactions between HCV and hepcidin, during acute and chronic disease, and putative alterations in cellular iron homeostasis that enhance HCV propagation and promote viral persistence. Thus, we used HCV JFH-1-infected co-cultures of Huh7.5 hepatoma and THP-1 macrophage cells, HCV patients' sera and Huh7 hepcidin-expressing cells transfected with HCV replicons. Hepcidin levels were elevated in acutely infected patients, but correlated with viral load in chronic patients. HAMP expression was up-regulated early in HCV infection in vitro, with corresponding changes in ferritin and FPN. Hepcidin overexpression enhanced both viral translation and replication. In HCV-infected co-cultures, we observed increased hepcidin, reduced hepatoma ferritin and a concurrent rise in macrophaghic ferritin over time. Altered iron levels complemented amplified replication in hepatoma cells and one replication round in macrophages. Iron-loading of macrophages led to enhancement of hepatic HCV replication through reversed ferritin "flow." Viral transmissibility from infected macrophages to naïve hepatoma cells was induced by iron. We propose that HCV control over iron occurs both by intracellular iron sequestration, through hepcidin, and intercellular iron mobilisation via ferritin, as means toward enhanced replication. Persistence could be achieved through HCV-induced changes in macrophagic iron that enhances viral replication in these cells.

HCV dsRNA-Activated Macrophages Inhibit HCV Replication in Hepatocytes

BACKGROUND

Macrophages play critical roles in innate immune response in the liver. Whether macrophages participate in liver innate immunity against HCV replication is poorly understood.

OBJECTIVES

The aim of this study was to investigate the role of macrophages in liver innate immunity against HCV replication.

MATERIALS AND METHODS

Freshly isolated monocytes were purified from peripheral blood of healthy adult donors. Macrophages refer to 7-day-cultured monocytes in vitro. A hepatoma cell line (Huh7) was infected with HCV JFH-1 to generate in vitro HCV infectious system. RT-PCR was used to determine HCV RNA and mRNA levels of genes expression. ELISA was used to measure the protein level of interferon-α (IFN-α) and western blot was used to determine protein expression level of Toll-like receptor 3 (TLR3).

RESULTS

HCV dsRNA induced the expression of type I IFN (IFN-α/β) in monocyte-derived macrophages. HCV dsRNA also induced the expression of TLR3 and IFN regulatory factor-7 (IRF-7), the key regulators of the IFN signaling pathway. When HCV JFH-1-infected Huh7 cells were co-cultured with macrophages activated with HCV dsRNA or incubated in media conditioned with supernatant (SN) from HCV dsRNA-activated macrophages, HCV replication was significantly suppressed. This macrophage SN action on HCV inhibition was mediated through type I IFN, which was evidenced by the observation that antibody to type I IFN receptor could neutralize the macrophages-mediated anti-HCV effect. The role of type I IFN in macrophages-mediated anti-HCV activity is further supported by the observation that HCV dsRNA-activated macrophages SN treatment induced the expression of several IFN-stimulated genes (ISGs), ISG15, ISG56, OAS-1, OAS-2, MxA and Viperin in HCV-infected Huh7 cells.

CONCLUSIONS

Macrophages may play an important role in liver innate immunity against HCV replication through a type I IFN-dependent mechanism.

Patient-derived hepatitis C virus inhibits CD4⁺ but not CD8⁺ T lymphocyte proliferation in primary T cells

Background

Hepatitis C virus (HCV) can replicate in cells of the immune system and productively propagate in primary T lymphocytes in vitro. We aimed to determine whether exposure to authentic, patient-derived HCV can modify the proliferation capacity, susceptibility to apoptosis and phenotype of T cells.

Methods

Primary total T cells from a healthy donor were used as targets and plasma-derived HCV from patients with chronic hepatitis C served as inocula. T cell phenotype was determined prior to and at different time points after exposure to HCV. T cell proliferation and apoptosis were measured by flow cytometry-based assays.

Results

The HCV inocula that induced the highest intracellular expression of HCV also caused a greatest shift in the T cell phenotype from predominantly CD4-positive to CD8-positive. This shift was associated with inhibition of CD4+ but not CD8+ T cell proliferation and did not coincide with altered apoptotic death of either cell subset.

Conclusions

The data obtained imply that exposure to native HCV can have an impact on the relative frequencies of CD4+ and CD8+ T cells by selectively suppressing CD4⁺ T lymphocyte proliferation and this may occur in both the presence and the absence of measurable HCV replication in these cells. If the virus exerts a similar effect in vivo, it may contribute to the impairment of virus-specific T cell response by altering cooperation between immune cell subsets.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-015-0322-4) contains supplementary material, which is available to authorized users.

Hepatitis C virus core protein enhances HIV-1 replication in human macrophages through TLR2, JNK, and MEK1/2-dependent upregulation of TNF-α and IL-6

Despite their differential cell tropisms, HIV-1 and HCV dramatically influence disease progression in coinfected patients. Macrophages are important target cells of HIV-1. We hypothesized that secreted HCV core protein might modulate HIV-1 replication. We demonstrate that HCV core significantly enhances HIV-1 replication in human macrophages by upregulating TNF-α and IL-6 via TLR2-, JNK-, and MEK1/2-dependent pathways. Furthermore, we show that TNF-α and IL-6 secreted from HCV core-treated macrophages reactivates monocytic U1 cells latently infected with HIV-1. Our studies reveal a previously unrecognized role of HCV core by enhancing HIV-1 infection in macrophages.

Hepatitis C virus 5' untranslated region variability correlates with treatment outcome

Hepatitis C virus (HCV) variability affects viral-host interactions. We analysed HCV 5'untranslated region (5'UTR) in sera and peripheral blood mononuclear cells (PBMC) from chronic hepatitis C patients undergoing antiviral treatment. We studied 139 patients treated with pegylated interferon and ribavirin. The primary endpoint was a sustained virological response (SVR) defined as negative HCV RNA level 24 weeks after the end of therapy. 5'UTR was analysed by single-strand conformational polymorphism (SSCP) and sequencing. The pretreatment SSCP pattern in serum and PBMC differed in 26 (18.7%) patients. During therapy, the SSCP pattern remained stable in 65 (60.8%) patients, number of bands declined in 16 (15.0%), and in 18 (16.8%) patients, changes were qualified as 'shift' indicating change in band positions. In univariate analysis, there was a significant (P ≤ 0.05) positive association between SVR and pretreatment serum and PBMC dissimilarities, initial viral load <10(6) IU/mL, IL-28B CC genotype of the rs12979860 single nucleotide polymorphism and change in the SSCP band pattern (either 'shift' or decline) In multivariable analysis, only low initial viral load, IL-28B genotype, and changes in the SSCP band pattern were independent factors associated with SVR. In conclusion, stability of 5'UTR correlated with infection persistence, while changes correlated with SVR.

Evidence of distinct populations of hepatitis C virus in the liver and plasma of patients co-infected with HIV and HCV

Viral diversity is an important predictor of hepatitis C virus (HCV) treatment response and may influence viral pathogenesis. HIV influences HCV variability in the plasma; however, limited data on viral variability are available from distinct tissue/cell compartments in patients co-infected with HIV and HCV. Thus, this exploratory study evaluated diversity of the hypervariable region 1 (HVR1) of HCV in the plasma and liver for 14 patients co-infected with HIV and HCV. Median intra-patient genetic distances and entropy values were similar in the plasma and liver compartments. Positive immune selection pressure was observed in the plasma for five individuals and in the liver for three individuals. Statistical evidence supporting viral compartmentalization was found in five individuals. Linear regression identified ALT (P = 0.0104) and AST (P = 0.0130) as predictors of viral compartmentalization. A total of 12 signature amino acids that distinguish liver from plasma E1/HVR1 were identified. One signature amino acid was shared by at least two individuals. These findings suggest that HCV compartmentalization is relatively common among patients co-infected with HIV and HCV. These data also imply that evaluating viral diversity, including drug resistance patterns, in the serum/plasma only may not adequately represent viruses replicating with in the liver and, thus, deserves careful consideration in future studies.

Hepatitis C virus (HCV) interaction with astrocytes: nonproductive infection and induction of IL-18

Hepatitis C virus (HCV) infection causes the central nervous system (CNS) abnormalities in more than 50 % of chronically infected subjects. However, the underlying mechanisms are largely unknown. In this study, we characterized the HCV interactions with astrocytes, one of the putative HCV target cells in the brain. We demonstrated that primary human astrocytes (PHA) were very inefficiently infected by HCV, either in the cell-free form or through cell-cell contact. We then determined the potential restriction steps of HCV infection and replication in these cells. PHA expressed all known HCV receptors but failed to support HCV entry. HCV IRES-mediated RNA translation was functional in PHA and further enhanced by miR122 expression. Nevertheless, PHA did not support HCV replication regardless of miR122 expression. To our great surprise, we found that HCV exposure induced robust IL-18 expression in PHA and exhibited direct neurotoxicity. Taken together, these results showed that astrocytes did not support productive HCV infection and replication, but HCV interactions with astrocytes and neurons alone might be sufficient to cause CNS dysfunction.

Serotonin and its implication in the side-effects of interferon-based treatment of patients with chronic viral hepatitis: Pharmacological interventions

Depression is a frequent side-effect of interferon-based treatment of patients with chronic viral hepatitis, that may lead to reduction or discontinuation of treatment. Clinical trials data showed the importance of therapy of psychiatric disorders for a successful antiviral treatment. Emerging evidence suggests that interferon may cause depression affecting serotonin synthesis via increased activity of indoleamine 2,3-dioxygenase. Serotonin reuptake inhibitors significantly improve mood disorders, but the use of these drugs requires caution because some studies reported the emergence of mania in patients treated for depression during antiviral therapy. Therefore, this review will examine and discuss the putative role of serotonin and its metabolism in the development of depression during antiviral therapy, focusing on pharmacological interventions to reduce side-effects.

Hepatitis C virus (HCV) infection of peripheral blood mononuclear cells in patients with type II cryoglobulinemia

OBJECTIVES

Type II cryoglobulinemia is a common extrahepatic manifestation of chronic hepatitis C virus (HCV) infection. The mechanisms behind its development are unclear, but could be related to direct infection of the immune cells.

METHODS

Peripheral blood mononuclear cells from 18 patients with type II cryoglobulinemia were separated into CD3+ (T cells), CD19+ (B cells) and CD14+ (monocytes) and analyzed for the presence of negative strand HCV RNA, which is a viral replicative intermediate, and for the presence of HCV non-structural protein 3 (NS3). Control group consisted of 182 consecutive chronic hepatitis C patients prior to initiation of antiviral therapy.

RESULTS

Negative strand HCV RNA was detected in PBMC from six (33.3%), patients and in 15 (8.2%) controls (p < 0.01). Negative strand was most frequently detected in B cells (3 patients), followed by T cells (2 patients), and monocytes (2 patients). One patient was positive both in CD3+ and CD14+ cells. NS3 protein was detected in six (33.3%) patients; five were positive in T cells, three in B cells, and another three were positive in monocytes. Two patients were positive in all analyzed cell subpopulation and one patient was positive in CD14+ and CD19+ cells, but not in CD3+ cells. Altogether, 11 patients (61.1%) were positive either for the negative strand HCV RNA or NS3 protein in at least one of the analyzed cell compartments.

CONCLUSION

Our findings of common presence of viral replication in cells of the immune system suggest that direct HCV infection could play a role in the etiology of cryoglobulinemia.

Intrahepatic IL-8 producing Foxp3⁺CD4⁺ regulatory T cells and fibrogenesis in chronic hepatitis C

BACKGROUND & AIMS

Regulatory CD4(+) T cells (Tregs) are considered to affect outcomes of HCV infection, because they increase in number during chronic hepatitis C and can suppress T-cell functions.

METHODS

Using microarray analysis, in situ immunofluorescence, ELISA, and flowcytometry, we characterised functional differentiation and localisation of adaptive Tregs in patients with chronic hepatitis C.

RESULTS

We found substantial upregulation of IL-8 in Foxp3(+)CD4(+) Tregs from chronic hepatitis C. Activated GARP-positive IL-8(+) Tregs were particularly enriched in livers of patients with chronic hepatitis C in close proximity to areas of fibrosis and their numbers were correlated with the stage of fibrosis. Moreover, Tregs induced upregulation of profibrogenic markers TIMP1, MMP2, TGF-beta1, alpha-SMA, collagen, and CCL2 in primary human hepatic stellate cells (HSC). HSC activation, but not Treg suppressor function, was blocked by adding a neutralizing IL-8 antibody.

CONCLUSIONS

Our studies identified Foxp3(+)CD4(+) Tregs as an additional intrahepatic source of IL-8 in chronic hepatitis C acting on HSC. Thus, Foxp3(+)CD4(+) Tregs in chronic hepatitis C have acquired differentiation as regulators of fibrogenesis in addition to suppressing local immune responses.

Effects of HCV on basal and tat-induced HIV LTR activation

Hepatitis C virus (HCV) co-infection occurs in ∼30–40% of the HIV-infected population in the US. While a significant body of research suggests an adverse effect of HIV on HCV replication and disease progression, the impact of HCV on HIV infection has not been well studied. Increasing data suggest that hepatocytes and other liver cell populations can serve as reservoirs for HIV replication. Therefore, to gain insight into the impact of HCV on HIV, the effects of the HCV Core protein and infectious hepatitis C virions were evaluated on basal and Tat-induced activation of the HIV long terminal repeat (LTR) in hepatocytes. The HIV LTR was highly induced by the HIV transactivator protein Tat in hepatocytes. Activation varied according to the number of NF-kB binding sites present in the LTRs from different HIV subtypes. Involvement of the NF-kB binding pathway in LTR activation was demonstrated using an NF-kB inhibitor and deletion of the NF-kB binding sites. TNFα, a pro-inflammatory cytokine that plays an important role in HIV pathogenesis, also induced LTR activity in hepatocytes. However, HIV LTR activity was suppressed in hepatocytes in the presence of HCV Core protein, and the suppressive effect persisted in the presence of TNFα. In contrast, infectious hepatitis C virions upregulated HIV LTR activation and gene transcription. Core-mediated suppression remained unaltered in the presence of HCV NS3/4A protein, suggesting the involvement of other viral/cellular factors. These findings have significant clinical implications as they imply that HCV could accelerate HIV disease progression in HIV/HCV co-infected patients. Such analyses are important to elucidate the mechanisms by which these viruses interact and could facilitate the development of more effective therapies to treat HIV/HCV co-infection.

Cytokines induced neutrophil extracellular traps formation: implication for the inflammatory disease condition

Neutrophils (PMNs) and cytokines have a critical role to play in host defense and systemic inflammatory response syndrome (SIRS). Neutrophil extracellular traps (NETs) have been shown to extracellularly kill pathogens, and inflammatory potential of NETs has been shown. Microbial killing inside the phagosomes or by NETs is mediated by reactive oxygen and nitrogen species (ROS/RNS). The present study was undertaken to assess circulating NETs contents and frequency of NETs generation by isolated PMNs from SIRS patients. These patients displayed significant augmentation in the circulating myeloperoxidase (MPO) activity and DNA content, while PMA stimulated PMNs from these patients, generated more free radicals and NETs. Plasma obtained from SIRS patients, if added to the PMNs isolated from healthy subjects, enhanced NETs release and free radical formation. Expressions of inflammatory cytokines (IL-1β, TNFα and IL-8) in the PMNs as well as their circulating levels were significantly augmented in SIRS subjects. Treatment of neutrophils from healthy subjects with TNFα, IL-1β, or IL-8 enhanced free radicals generation and NETs formation, which was mediated through the activation of NADPH oxidase and MPO. Pre-incubation of plasma from SIRS with TNFα, IL-1β, or IL-8 antibodies reduced the NETs release. Role of IL-1β, TNFα and IL-8 thus seems to be involved in the enhanced release of NETs in SIRS subjects.

Unexpected maintenance of hepatitis C viral diversity following liver transplantation

Chronic hepatitis C virus (HCV) infection can lead to liver cirrhosis in up to 20% of individuals, often requiring liver transplantation. Although the new liver is known to be rapidly reinfected, the dynamics and source of the reinfecting virus(es) are unclear, resulting in some confusion concerning the relationship between clinical outcome and viral characteristics. To clarify the dynamics of liver reinfection, longitudinal serum viral samples from 10 transplant patients were studied. Part of the E1/E2 region was sequenced, and advanced phylogenetic analysis methods were used in a multiparameter analysis to determine the history and ancestry of reinfecting lineages. Our results demonstrated the complexity of HCV evolutionary dynamics after liver transplantation, in which a large diverse population of viruses is transmitted and maintained for months to years. As many as 30 independent lineages in a single patient were found to reinfect the new liver. Several later posttransplant lineages were more closely related to older pretransplant viruses than to viruses detected immediately after transplantation. Although our data are consistent with a number of interpretations, the persistence of high viral genetic variation over long periods of time requires an active mechanism. We discuss possible scenarios, including frequency-dependent selection or variation in selective pressure among viral subpopulations, i.e., the population structure. The latter hypothesis, if correct, could have relevance to the success of newer direct-acting antiviral therapies.

CD44 participates in IP-10 induction in cells in which hepatitis C virus RNA is replicating, through an interaction with Toll-like receptor 2 and hyaluronan

The mechanisms of induction of liver injury during chronic infection with hepatitis C virus (HCV) are not well understood. Gamma interferon (IFN-γ)-inducible protein 10 (IP-10), a member of the CXC chemokine family, is expressed in the liver of chronic hepatitis C (CHC) patients and selectively recruits activated T cells to the sites of inflammation. Recently, it was shown that a low plasma concentration of IP-10 in CHC patients was closely associated with the outcome of antiviral therapy. In this study, we examined the role of the Toll-like receptor (TLR) pathway on IP-10 production in cells replicating HCV. Among the CXC chemokines, the expression of IP-10 was specifically increased in cells replicating HCV upon stimulation with conventional TLR2 ligands. The enhancement of IP-10 production upon stimulation with TLR2 ligands in cells replicating HCV induced CD44 expression. CD44 is a broadly distributed type I transmembrane glycoprotein and a receptor for the glycosaminoglycan hyaluronan (HA). In CHC patients, the expression of HA in serum has been shown to increase in accord with the progression of liver fibrosis, and HA also works as a ligand for TLR2. In the present study, IP-10 production upon HA stimulation was dependent on the expression of TLR2 and CD44, and a direct association between TLR2 and CD44 was observed. These results suggest that endogenous expression of HA in hepatocytes in CHC patients participates in IP-10 production through an engagement of TLR2 and CD44.

Cross-presentation of antigen by diverse subsets of murine liver cells

Antigen cross-presentation is a principal function of specialized antigen-presenting cells of bone marrow origin such as dendritic cells. Although these cells are sometimes known as "professional" antigen-presenting cells, nonbone marrow-derived cells may also act as antigen-presenting cells. Here, using four-way liver cell isolation and parallel comparison of candidate antigen-presenting cells, we show that, depending on the abundance of antigen-donor cells, different subsets of liver cells could cross-present a hepatocyte-associated antigen. This function was observed in both liver sinusoidal endothelial cells and Kupffer cells even at very low antigen concentration, as well as when using soluble protein. Antigen cross-presentation by liver cells induced efficient CD8+ T-cell proliferation in a similar manner to classical dendritic cells from spleen. However, proliferated cells expressed a lower level of T-cell activation markers and intracellular interferon-gamma levels. In contrast to classical spleen dendritic cells, cross-presentation by liver antigen-presenting cells was predominantly dependent on intercellular adhesion molecule-1.

CONCLUSION

Hepatic sinusoids are an environment rich in antigen cross-presenting activity. However, the liver's resident antigen-presenting cells cause partial T-cell activation. These results clarify how the liver can act as a primary site of CD8+ T-cell activation, and why immunity against hepatocyte pathogens is sometimes ineffective.

The liver-cytokine-brain circuit in interferon-based treatment of patients with chronic viral hepatitis

Psychiatric symptoms are commonly identified in patients with viral hepatitis. They may have been present prior to the onset of disease and may include symptoms related to addiction issues. Furthermore, the virus and antiviral therapy, in particular interferon, may induce or modify psychiatric symptoms. Recent data support chronic hepatitis C replication in the brain and subsequent changes of cerebral metabolite spectra and magnetic resonance alterations. In chronic viral hepatitis and in other chronic inflammatory diseases, an alteration of the neuro-endocrine-immune system response has been observed. Catecholamines and glucocorticoids modulate this immune/inflammatory reaction. Psychiatric assessment and monitoring before, during and after antiviral therapy can identify patients whose psychiatric symptoms preclude therapy, and those who may benefit from psychopharmacological therapy and counselling, thereby improving therapeutic results. This review will discuss current insights into the complex interplay between cytokines, liver and brain in chronic viral hepatitis closely associated with psychiatric issues, especially in the case of antiviral therapy, with the aim of indicating future research and possible treatments.

Human cell types important for hepatitis C virus replication in vivo and in vitro: old assertions and current evidence

Hepatitis C Virus (HCV) is a single stranded RNA virus which produces negative strand RNA as a replicative intermediate. We analyzed 75 RT-PCR studies that tested for negative strand HCV RNA in liver and other human tissues. 85% of the studies that investigated extrahepatic replication of HCV found one or more samples positive for replicative RNA. Studies using in situ hybridization, immunofluorescence, immunohistochemistry, and quasispecies analysis also demonstrated the presence of replicating HCV in various extrahepatic human tissues, and provide evidence that HCV replicates in macrophages, B cells, T cells, and other extrahepatic tissues. We also analyzed both short term and long term in vitro systems used to culture HCV. These systems vary in their purposes and methods, but long term culturing of HCV in B cells, T cells, and other cell types has been used to analyze replication. It is therefore now possible to study HIV-HCV co-infections and HCV replication in vitro.

Hepatitis C virus core protein induces neuroimmune activation and potentiates Human Immunodeficiency Virus-1 neurotoxicity

Background

Hepatitis C virus (HCV) genomes and proteins are present in human brain tissues although the impact of HIV/HCV co-infection on neuropathogenesis remains unclear. Herein, we investigate HCV infectivity and effects on neuronal survival and neuroinflammation in conjunction with HIV infection.

Methodology

Human microglia, astrocyte and neuron cultures were infected with cell culture-derived HCV or exposed to HCV core protein with or without HIV-1 infection or HIV-1 Viral Protein R (Vpr) exposure. Host immune gene expression and cell viability were measured. Patch-clamp studies of human neurons were performed in the presence or absence of HCV core protein. Neurobehavioral performance and neuropathology were examined in HIV-1 Vpr-transgenic mice in which stereotaxic intrastriatal implants of HCV core protein were performed.

Principal Findings

HCV-encoded RNA as well as HCV core and non-structural 3 (NS3) proteins were detectable in human microglia and astrocytes infected with HCV. HCV core protein exposure induced expression of pro-inflammatory cytokines including interleukin-1β, interleukin-6 and tumor necrosis factor-α in microglia (p<0.05) but not in astrocytes while increased chemokine (e.g. CXCL10 and interleukin-8) expression was observed in both microglia and astrocytes (p<0.05). HCV core protein modulated neuronal membrane currents and reduced both β-III-tubulin and lipidated LC3-II expression (p<0.05). Neurons exposed to supernatants from HCV core-activated microglia exhibited reduced β-III-tubulin expression (p<0.05). HCV core protein neurotoxicity and interleukin-6 induction were potentiated by HIV-1 Vpr protein (p<0.05). HIV-1 Vpr transgenic mice implanted with HCV core protein showed gliosis, reduced neuronal counts together with diminished LC3 immunoreactivity. HCV core-implanted animals displayed neurobehavioral deficits at days 7 and 14 post-implantation (p<0.05).

Conclusions

HCV core protein exposure caused neuronal injury through suppression of neuronal autophagy in addition to neuroimmune activation. The additive neurotoxic effects of HCV- and HIV-encoded proteins highlight extrahepatic mechanisms by which HCV infection worsens the disease course of HIV infection.

Investigating health-related quality of life, mood and neuropsychological test performance in a homogeneous cohort of Irish female hepatitis C patients

Neurocognitive dysfunction has been reported in individuals with chronic hepatitis C (CHC) infection, but HCV populations investigated have often included participants with numerous potential confounding comorbidities. This pilot study sought to investigate functional capacity and neurocognitive function in a homogeneous state-infected HCV population with histologically defined mild liver disease, free from the comorbid factors typically associated with HCV populations. A further aim was to examine cognitive function in a treatment naive population with a similar history of iatrogenic HCV exposure and spontaneous viral clearance. A convenience sample of 29 women, all of whom were carefully screened to exclude relevant comorbidities, was recruited to the study. Twenty women with a history of iatrogenic HCV exposure were recruited from prospective specialist tertiary care liver clinics. A comparison group of healthy controls (n = 9) was also assessed. Study participants underwent mood, health-related quality of life and neuropsychological assessment. CHC patients reported significantly higher levels of cognitive fatigue than healthy controls (F = 3.4, P = 0.04). On cognitive testing, CHC patients showed impairments compared with healthy controls on estimates of general memory [F(2,25) = 4.1, P = 0.03, partial eta squared = 0.25], delayed auditory recognition [F(2,25) = 4.2, P = 0.03, partial eta squared= 0.22] and sustained attention [F(2,25) = 3.6, P = 0.04, partial eta squared = 0.22]. Increased cognitive fatigue only correlated with delayed auditory memory recall ability (r = 0.724, P = 0.006). In conclusion, these findings appear to support the presence of neurocognitive abnormalities in an iatrogenically infected, homogeneous female HCV population who were carefully screened to eliminate other factors affecting neurocognitive test performance and may indicate underlying neurophysiological causative mechanisms.

Human peritoneal macrophages from ascitic fluid can be infected by a broad range of HIV-1 isolates

Macrophages are major HIV target cells. They support both productive and latent HIV-1 infection. Susceptibility of primary macrophages to HIV depends on the anatomical location and activation state of the cells. We demonstrate that peritoneal macrophages (PMs) are abundant in ascitic fluid of patients with liver cirrhosis and are susceptible to HIV-1 infection. PMs expressed CD68, a differentiation marker, exhibited phagocytic activity, and survived in culture for 2 months without additional growth factors. Freshly isolated PMs were susceptible to HIV-1 R5 strains but not to X4-T-cell line-adapted strains. Interestingly, after 7 days in culture, PMs acquired susceptibility to X4-T-cell line-adapted strains. HIV entry inhibitors, TAK779 and AMD3100, blocked HIV infection of PMs, indicating that infection by R5 and X4 strains was mediated by CCR5 and CXCR4, respectively. Although PMs did not express detectable cell surface levels of CXCR4 and CCR5, they did express mRNAs of these HIV coreceptors and responded to stimulation by their natural ligands, SDF-1alpha and RANTES. PMs were susceptible to HIV-1 X4, R5, and X4R5 primary isolates. PMs after 7 days in culture produced greater amounts of X4 and X4R5 HIV than freshly isolated PMs. The day-7 PMs were more susceptible to R5 infection in a single-cycle infection assay, but there was no increase in viral production in a multiple-round infection assay. The level of CXCR4 mRNA and production of CC-chemokines (MIP-1alpha, MIP-1beta, and RANTES) increased significantly during 7 days in culture. Our results indicate that PMs are susceptible to receptor-mediated infection by a broad range of HIV strains. These primary macrophages could provide a valuable system for investigating the role of primary macrophages in HIV pathogenesis.

Hepatitis C virus RNA localization in human carotid plaques

BACKGROUND

Hepatitis C virus (HCV) infection has certain characteristics that enable it to play an important role in atherosclerosis. Some studies report its association with an increased risk of carotid artery plaque.

OBJECTIVES

The aim of this study was to evaluate the presence of HCV genomic sequences and replicative intermediates in plaque tissues.

STUDY DESIGN

A cohort of consecutive, prospectively recruited patients with HCV infection and chronic ischemic heart disease from the Cardiology, Vascular Surgery and Hepatology Units of a University Hospital in Florence, Italy, were studied.

RESULTS

Positive-strand HCV RNA was detected in seven carotid plaque tissues from anti-HCV-positive patients and was not detected in the nine carotid plaque tissues obtained from anti-HCV-negative patients. In three patients, HCV RNA was found in carotid plaque and not in serum. HCV replicative intermediates were detected in three plaque samples. Direct sequencing of HCV RNA from the plaque and serum showed HCV genotypes 2 (five cases) and 1 (two cases).

CONCLUSIONS

The novel finding of HCV RNA sequences in plaque tissue strongly suggests an active local infection. This in turn makes it conceivable that the virus may exert local action in carotid atherosclerosis.

Hepatitis C virus and peripheral blood mononuclear cell reservoirs Patricia Baré

The existence of hepatitis C virus (HCV) infection in extrahepatic sites has been widely demonstrated. Since peripheral blood mononuclear cells have been the most investigated, compelling evidence of an association with HCV has been shown. Different studies have revealed that HCV RNA can persist and replicate in immune cells but the relevance of its presence and persistence over time is still unknown. As the contribution of this extrahepatic reservoir could have several clinical implications in viral transmission, treatment response and disease pathogenesis, future studies are required to improve our knowledge of the extrahepatic manifestations of HCV and its possible consequences.

Chronic hepatitis C and persistent occult hepatitis C virus infection are characterized by distinct immune cell cytokine expression profiles

Hepatitis C virus (HCV) replicates in immune cells in both chronic hepatitis C (CHC) and occult HCV infection, but the extent of virus replication in this compartment in these opposing infection forms varies greatly. It was unknown whether this could be linked to HCV genotype or to differences in host gene expression shaping the immune response, and whether HCV replication in immune cells is sensitive to endogenous antiviral cytokines. In this study, we uncovered that significantly greater HCV load in peripheral blood mononuclear cells (PBMC), but not in plasma, coincided with HCV genotypes 2 and 3 in CHC, but with genotype 1 in residual occult infection after clinical resolution of hepatitis C. Moreover, PBMC from individuals with occult infection transcribed significantly greater levels of IFN-alpha, IFN-gamma and TNF-alpha, but less interleukin (IL)-10 than those from CHC. In CHC, PBMC with low HCV load expressed significantly more IFN-gamma but less IL-12 than did cells with high virus content. In occult infection, HCV RNA detection in PBMC was associated with much lower IFN-alpha and IL-12 expression. Further, HCV replication in T lymphocytes could be completely eliminated by activation of endogenous IFN-gamma in CHC, but of IFN-alpha in occult infection. In conclusion, CHC and persistent occult HCV infection are characterized by clearly different profiles of antiviral cytokine response in circulating immune cells which are also different from those of healthy individuals. Higher expression of IL-10, combined with lower transcription of IFN-alpha, IFN-gamma and TNF-alpha, is associated with a more robust HCV replication in immune cells.

Gene expression profile of Huh-7 cells expressing hepatitis C virus genotype 1b or 3a core proteins

BACKGROUND

The liver disease expression in chronic hepatitis C patients is variable and may partially depend on the sequence of the infecting viral genotype.

AIM

To identify some hepatitis C virus (HCV) genotype-specific virus-host interactions potentially leading to clinically significant consequences.

METHODS

We compared the gene expression profile of Huh-7 cells transiently expressing the core protein of HCV genotype 1b and 3a using microarray technology.

RESULTS

Thirty-two genes were overexpressed in Huh-7 transfected with the HCV genotype 1b core protein and 57 genes in cells transfected with the genotype 3a core protein. On the other hand, we found 20 genes downregulated by core 1b and 31 genes by core 3a. These included genes involved in lipid transport and metabolism, cell cycle, immune response and insulin signalling.

CONCLUSION

The expression of HCV core proteins of different genotypes leads to a specific gene expression profile. This may account for the variable disease expression associated with HCV infection.

Hepatitis C, insulin resistance and diabetes: clinical and pathogenic data

Epidemiological data indicate a strong risk for development of insulin resistance (IR), and, ultimately, overt diabetes mellitus (DM) in patients with chronic hepatitis C virus (HCV) infection. Steatosis, or fatty liver, is closely linked with IR in persons without HCV, such as those with metabolic syndrome, primarily due to increased visceral fat leading to altered adipokine production and increased free fatty acid (FFA) release. Moreover, there is evidence that liver fat can have an impact on the development of hepatic IR independently of changes in adipose tissue. Multiple mechanisms can account for the development of IR in patients with chronic HCV. In particular, there is evidence for a triangular interaction between steatosis, inflammatory processes and IR. In patients infected by the genotype 1 virus, steatosis is strongly related to IR, leading to a metabolic steatosis, while, in genotype 3 patients, steatosis is related to viral load in the context of a viral steatosis. Chronic inflammatory processes in the liver may be mediated by persistently activated macrophages and other immune cells, with concomitant overproduction of pro-inflammatory cytokines such as tumour necrosis factor-alpha. Activation of inflammatory pathways, together with increased levels of FFAs, can disrupt hepatocyte intracellular pathways and inhibit insulin signalling, leading to IR. Molecular studies have also shown that the HCV core protein can directly inhibit the insulin signalling pathway and increase reactive oxygen species production, both of which can further exacerbate IR. The available data provide an understanding of chronic HCV whereby chronic inflammatory processes, steatosis and IR contribute to each other, leading to an increased risk of DM, and its associated poor outcomes, in persons with chronic HCV.

Hepatitis C virus neuroinvasion: identification of infected cells

Hepatitis C virus (HCV) infection often is associated with cognitive dysfunction and depression. HCV sequences and replicative forms were detected in autopsy brain tissue and cerebrospinal fluid from infected patients, suggesting direct neuroinvasion. However, the phenotype of cells harboring HCV in brain remains unclear. We studied autopsy brain tissue from 12 HCV-infected patients, 6 of whom were coinfected with human immunodeficiency virus. Cryostat sections of frontal cortex and subcortical white matter were stained with monoclonal antibodies specific for microglia/macrophages (CD68), oligodendrocytes (2',3'-cyclic nucleotide 3'-phosphodiesterase), astrocytes (glial fibrillary acidic protein [GFAP]), and neurons (neuronal-specific nuclear protein); separated by laser capture microscopy (LCM); and tested for the presence of positive- and negative-strand HCV RNA. Sections also were stained with antibodies to viral nonstructural protein 3 (NS3), separated by LCM, and phenotyped by real-time PCR. Finally, sections were double stained with antibodies specific for the cell phenotype and HCV NS3. HCV RNA was detected in CD68-positive cells in eight patients, and negative-strand HCV RNA, which is a viral replicative form, was found in three of these patients. HCV RNA also was found in astrocytes from three patients, but negative-strand RNA was not detected in these cells. In double immunostaining, 83 to 95% of cells positive for HCV NS3 also were CD68 positive, while 4 to 29% were GFAP positive. NS3-positive cells were negative for neuron and oligodendrocyte phenotypic markers. In conclusion, HCV infects brain microglia/macrophages and, to a lesser extent, astrocytes. Our findings could explain the biological basis of neurocognitive abnormalities in HCV infection.

Defective response to Toll-like receptor 3 and 4 ligands by activated monocytes in chronic hepatitis C virus infection

Toll-like receptors (TLR) have a critical role in innate immunity against pathogens. We investigated the cytokine response to TLR stimulation in peripheral blood cells of subjects infected with hepatitis C virus (HCV) and/or human immunodeficiency virus (HIV) in the Women Interagency HIV Study (WIHS) cohort. Interleukin (IL)-6 in response to TLR3 and TLR4 ligands such as polyinosinic-polycytidylic acid and lipopolysaccharide was significantly compromised in HCV-infected women. High spontaneous secretion of IL-6 suggested pre-existing cell activation as a factor mediating reduced responses to TLR3 and TLR4 stimulation. To a lesser extent, tumour necrosis factor-alpha and IL-1beta responses to TLR stimulation were also compromised. Monocytes, but not B cells or NK cells, were identified as the cell population spontaneously secreting cytokines and also as the cells responding to TLR stimulation. These results highlight a functional defect in antigen-presenting cells of women with HCV infection or co-infection. In women with existing HIV co-infection, decreased cytokine function of antigen-presenting cells suggests another mechanism contributing to immune dysfunction in addition to the HIV-associated CD4 defect.

Cognitive dysfunction in chronic hepatitis C: a review

The hepatitis C virus (HCV) is a common blood-borne illness that affects up to 2% of the world's population and almost 4 million Americans. Cognitive impairment, or difficulty with thinking, has become a well-established symptom in persons with end stage liver disease. It was previously assumed that cognitive impairment was a consequence of cirrhosis-associated hepatic encephalopathy. Recent evidence, however, suggests that approximately one-third of people with chronic HCV experience cognitive impairment even in the absence of cirrhosis and that its occurrence is unrelated to other indices of liver function, such as laboratory values, viral load, and genotype. In the present review, evidence outlining the presence of cognitive deficits associated with HCV, possible etiological factors, effects of antiviral therapy, and co-infection with human immunodeficiency virus (HIV) is presented. Implications of these findings and directions for future work are discussed.

Therapeutic control of hepatitis C virus: the role of neutralizing monoclonal antibodies

Liver failure associated with hepatitis C virus (HCV) accounts for a substantial portion of liver transplantation. Although current therapy helps some patients with chronic HCV infection, adverse side effects and a high relapse rate are major problems. These problems are compounded in liver transplant recipients as reinfection occurs shortly after transplantation. One approach to control reinfection is the combined use of specific antivirals together with HCV-specific antibodies. Indeed, a number of human and mouse monoclonal antibodies to conformational and linear epitopes on HCV envelope proteins are potential candidates, since they have high virus neutralization potency and are directed to epitopes conserved across diverse HCV genotypes. However, a greater understanding of the factors contributing to virus escape and the role of lipoproteins in masking virion surface domains involved in virus entry will be required to help define those protective determinants most likely to give broad protection. An approach to immune escape is potentially caused by viral infection of immune cells leading to the induction hypermutation of the immunoglobulin gene in B cells. These effects may contribute to HCV persistence and B cell lymphoproliferative diseases.

Antiproliferative effect of hepatitis C virus on mitogen-stimulated peripheral blood mononuclear cells: potential role in viral persistence in Egyptian patients

OBJECTIVES

We aimed to study the effect of hepatitis C virus (HCV) and sera of chronic HCV patients on phytohemagglutinin (PHA)-stimulated normal donor PBMCs and to study the effect of chronic HCV infection on some cytokine profile.

SUBJECTS AND METHODS

(3)H-Thymidine uptake was utilized to study effect of pelleted virus and patients sera on PBMCs proliferation in vitro. The study included 337 Egyptian chronic liver patients from Ain Shams University Hospitals and 90 healthy control subjects. The patients' group included chronic hepatitis C (250 subjects), and other chronic liver diseases (87 subjects). All subjects' sera were subjected to RT-PCR for HCV RNA detection, IL-4, IL-1beta, and TNF-alpha measurement by EIA, and biochemical measurement of ALT and albumin.

RESULTS

Treatment of PHA-stimulated normal donor PBMCs with pelleted virus led to decrease (dose response) in their rate of proliferation. This was partially reversed after addition of HCV RNA positive patients' sera. HCV RNA positive patients were significantly higher in IL-4 and ALT, and lower in IL-1beta and albumin than HCV RNA negative patients.

CONCLUSION

HCV infection suppresses early immune response. This leads to increased IL-4 Th2 cytokine.

Antagonistic expression of hepatitis C virus and alpha interferon in lymphoid cells during persistent occult infection

Detection of residual HCV in individuals with SVR after treatment of CHC can be significantly heightened by analyzing ex vivo mitogen-activated T and B lymphocytes and applying sensitive nucleic acid amplification assays. However, it remained unknown if synergistic activation of lymphocytes and monocytes would further augment HCV detection, if viral replication becomes universally upregulated in treated cells, and if examining sequential sera and lymphoid cells would improve detection of occult infection. Using paired sera and lymphoid cells collected 1 year apart from 17 individuals with normal liver enzymes for up to 72 months after SVR, it was found that simultaneous activation of lymphocytes and monocytes enhanced identification of silent HCV infection and revealed that in some cases monocytes were the principal immune cell type where HCV persisted. Testing of serial samples further increased detection of occult infection. Ultimately, by combining the above two approaches, all individuals with SVR were found to be silent carriers of HCV. Clonal sequencing revealed HCV variations in sera and lymphoid cells and evolution of viral genomes confirming ongoing virus replication. Surprisingly, similar to those with CHC, naive lymphoid cells from some individuals carried approximately 10(3) HCV copies/microg total RNA. HCV loads in naive lymphoid cells predetermined the outcome of ex vivo stimulation with respect to upregulation or inhibition of HCV replication. HCV RNA levels in occult infection were inversely proportional to the expression of IFNalpha and IFN-inducible MxA, but not to IFNgamma or tumour necrosis factor alpha in naive and mitogen-treated lymphoid cells.

Expression of the alternative reading frame protein of Hepatitis C virus induces cytokines involved in hepatic injuries

Hepatitis C virus (HCV) Core has been implicated in immune-mediated mechanisms associated with the development of chronic hepatic diseases. Discovery of different alternative reading frame proteins (ARFPs) expressed from the HCV Core coding sequence challenges properties assigned to Core. This study was designed to evaluate the immunomodulatory functions of Core and ARFPs in monocytes, dendritic cells (DCs), macrophages (Mphi) and hepatocytes, cells that are all capable of supporting HCV replication. THP-1 cells, monocyte-derived Mphi and DCs, and Huh7 cells were infected by using adenoviruses (Ad) encoding Core, CE1E2 and a Core sequence modified so that the Core protein is wild type, but no ARFPs are expressed (CDeltaARFP). THP-1 cells and DCs infected with Ad encoding Core or CE1E2 produced significant levels of interleukin-6 (IL-6), IL-8, MCP-1 and MIP-1beta, whereas production of these chemokines with AdCDeltaARFP was reduced or abolished. Similar effects on IL-8 production were observed in Huh7 cells and on IL-6 and MIP-1beta in Mphi. Wild-type Core sequence, but not CDeltaARFP, could trans-activate the IL-8 promoter and this activation was not associated with activation of p38/p42-44MAPK. This study illustrates, for the first time, the critical importance of ARFP expression in immunomodulatory functions attributed to Core expression and suggests a potential involvement of ARFP in mechanisms associated with HCV pathogenesis.

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

BACKGROUND & AIMS

Approximately half of hepatitis C virus (HCV)-infected patients do not respond to current interferon (IFN)-alpha combination therapy. To understand IFN-alpha resistance in vivo, we examined the dynamic responses to both type I and type II IFNs, human IFN (hIFN)-alpha, -gamma, and consensus IFN, in the chimpanzee model.

METHODS

Naive and HCV-infected chimpanzees were treated with 3 forms of hIFNs in vivo. Quantitative real-time polymerase chain reaction was performed to evaluate the expression of IFN-stimulated genes (ISGs) in both peripheral blood mononuclear cells and liver to compare the responses to hIFN between naive and infected chimpanzees. The hepatic expression of IFN signaling components and inhibitory regulators including suppressor of cytokine signaling 3 (SOCS3) were assessed. SOCS3 expression was also evaluated in the liver of HCV-infected patients undergoing IFN treatment.

RESULTS

The in vivo responses to all 3 hIFNs were much lower in the HCV-infected chimpanzees than those in the naive chimpanzees. This defect was particularly evident in the liver because induction of hepatic ISGs was barely detectable in the infected animals. Following IFN administration, the expression of SOCS3 was significantly up-regulated, possibly through induction of interleukin-6, in the liver of HCV-infected chimpanzees. HCV-infected humans also showed a differential pattern of hepatic SOCS3 expression in response to IFN that is associated with treatment response.

CONCLUSIONS

Our data indicate a predominantly defective hepatic response to IFN in HCV-infected chimpanzees, which is probably mediated through the activation of SOCS3 and may explain the nonresponse of many HCV patients to IFN-based therapy.

De novo infection and propagation of wild-type Hepatitis C virus in human T lymphocytes in vitro

While exploring previous findings that ex vivo treatment of lymphoid cells from Hepatitis C virus (HCV)-infected individuals with T cell-stimulating mitogens augments detection of the residing virus, an in vitro HCV replication system was established, in which mitogen-induced T cell-enriched cultures served as HCV targets and the derived T cells multiplied virus during repeated serial passage. HCV replication was ascertained by detecting HCV RNA positive and negative strands, HCV NS5a and E2 proteins, release of HCV virions and nucleocapsids (confirmed by immunoelectron microscopy) and de novo infection of mitogen-induced T cells prepared from healthy donors. Further, affinity-purified normal human T lymphocytes were also susceptible to HCV infection in vitro and HCV replication was detected in pure T cells isolated from a patient with chronic hepatitis C. These results document that T cells can support propagation of HCV both in vivo and in vitro. The infection system established offers a valuable tool for in vitro studies on the entire cycle of HCV replication, virus cytopathogenicity and evaluation of antiviral agents against wild-type HCV in the natural host-cell milieu.

Extrahepatic replication of HCV: insights into clinical manifestations and biological consequences

An estimated 170 million persons are infected with the hepatitis C virus (HCV) worldwide. While hepatocytes are the major site of infection, a broad clinical spectrum of extrahepatic complications and diseases are associated with chronic HCV infection, highlighting the involvement of HCV in a variety of non-hepatic pathogenic processes. There is a growing body of evidence to suggest that HCV can replicate efficiently in extrahepatic tissues and cell types, including peripheral blood mononuclear cells. Nonetheless, laboratory confirmation of HCV replication in extrahepatic sites is fraught with technical challenges, and in vitro systems to investigate extrahepatic replication of HCV are severely limited. Thus, future studies of extrahepatic replication should combine innovative in vitro assays with a prospective cohort design to maximize our understanding of this important phenomenon to the pathogenesis and treatment response rates of HCV.

Hepatitis C virus infection of primary tupaia hepatocytes leads to selection of quasispecies variants, induction of interferon-stimulated genes and NF-κB nuclear translocation

Systems for in vitro culture of Hepatitis C virus (HCV) are essential tools to analyse virus–cell interactions and to investigate relevant pathophysiological aspects of HCV infection. Although the HCV replicon methodology has increased our understanding of HCV biology, this system does not reproduce the natural infection. Recently, tupaia (Tupaia belangeri chinensis) hepatocytes have been utilized for in vitro culture of HCV. In the present work, primary tupaia hepatocytes infected in vitro with HCV were used to analyse the evolution of HCV quasispecies in infected cells and the ability of the virus to influence antiviral and proinflammatory responses in cells sustaining virus replication. The results confirmed the potential of tupaia hepatocytes as a model for HCV infection, although this system is limited by rapid loss of differentiated cell phenotype in culture. These findings revealed an extraordinary plasticity of HCV quasispecies, which underwent rapid evolution to tupaia-tropic variants as early as 24 h after infection. It was also shown that HCV could activate interferon-sensitive genes, albeit modestly in comparison with other viruses such as Semliki Forest virus. Importantly, HCV activated NF-κB in primary hepatocytes and upregulated NF-κB-responsive genes including the chemokines MCP-1 and CXCL2 (MIP-2). This effect may play a role in induction of the hepatic inflammatory reaction in vivo. In summary, HCV quasispecies adapt rapidly to the specific biology of the host and HCV stimulates a blunted interferon response while inducing a proinflammatory phenotype in the infected cell.

Emerging evidence of hepatitis C virus neuroinvasion

It has been reported that hepatitis C virus (HCV) infection is associated with cognitive dysfunction, fatigue and depression, which do not correlate with the severity of liver disease and cannot be accounted for by hepatic encephalopathy or drug abuse. There is also emerging evidence that HCV infection can have negative neurocognitive effects in HIV-infected cohorts. Magnetic resonance spectroscopy has suggested the likely existence of a biological basis for these effects. HCV replicative forms have recently been detected in autopsy brain tissue and the infected cells have been identified as CD68-positive (macrophages/microglia). These findings raise the possibility that HCV infection of the brain could be directly related to the reported neuropsychological and cognitive changes. HCV is not strictly hepatotropic, as it can also replicate in leukocytes, including monocytes/macrophages. The latter cells could provide access of HCV into the central nervous system ('Trojan horse' mechanism) in a process similar to that postulated for HIV-1. In support of this hypothetical mechanism come reports showing a close relationship between HCV sequences present in the brain and cerebrospinal fluid and sequences found in lymph nodes and peripheral blood mononuclear cells. However, despite some similarities there is a fundamental difference between HIV-1 and HCV infection as the latter does not progress into AIDS-type dementia.

Hepatitis C virus E2-CD81 interaction induces hypermutation of the immunoglobulin gene in B cells

Hepatitis C virus (HCV) is one of the leading causes of chronic liver diseases and B-lymphocyte proliferative disorders, including mixed cryoglobulinemia and B-cell lymphoma. It has been suggested that HCV infects human cells through the interaction of its envelope glycoprotein E2 with a tetraspanin molecule CD81, the putative viral receptor. Here, we show that the engagement of B cells by purified E2 induced double-strand DNA breaks specifically in the variable region of immunoglobulin (V(H)) gene locus, leading to hypermutation in the V(H) genes of B cells. Other gene loci were not affected. Preincubation with the anti-CD81 monoclonal antibody blocked this effect. E2-CD81 interaction on B cells triggered the enhanced expression of activation-induced cytidine deaminase (AID) and also stimulated the production of tumor necrosis factor alpha. Knockdown of AID by the specific small interfering RNA blocked the E2-induced double-strand DNA breaks and hypermutation of the V(H) gene. These findings suggest that HCV infection, through E2-CD81 interaction, may modulate host's innate or adaptive immune response by activation of AID and hypermutation of immunoglobulin gene in B cells, leading to HCV-associated B-cell lymphoproliferative diseases.

Nonstructural proteins 4A and 4B of hepatitis C virus transactivate the interleukin 8 promoter

Interleukin 8 (IL-8) is induced in many cell types by various stimuli including virus infection. It was reported that nonstructural protein 5A (NS5A) of hepatitis C virus (HCV) was involved in induction of IL-8 expression at both mRNA and protein levels in cultured human cells. In this study, we aimed to determine whether or not another HCV protein(s) transactivates the IL-8 gene expression, by means of an IL-8 promoter-driven luciferase reporter assay and measurement of endogenous IL-8 mRNA and secreted IL-8 protein levels. We observed that NS4B, and NS4A to a lesser extent, significantly transactivated the IL-8 promoter, which resulted in enhanced production of IL-8 protein. Also, the IL-8 expression was augmented in Huh-7 cells harboring an HCV subgenomic RNA replicon, compared with the control cells. Deletion mutational analysis of the IL-8 promoter revealed the possible involvement of the transcription factor AP-1 in both NS4A- and NS4B-mediated IL-8 gene activation. In addition, the IL-8 gene activation by NS4B, but not that by NS4A, was likely to involve NF-kappaB and/or NFIL-6. The degree of the transactivation by NS4B and NS4A varied with different human cell lines, with HeLa cells showing the strongest activation followed by Huh-7 cells, and with HepG2 cells exhibiting a marginal level of activation. Taken together, our present results suggest the possibility that NS4B and NS4A play an important role in inducing the IL-8 gene expression under certain cellular conditions, which might be one of the strategies to establish persistent HCV infection.