Continuous release of hepatitis C virus (HCV) by peripheral blood mononuclear cells and B-lymphoblastoid cell-line cultures derived from HCV-infected patients

Hepatitis C virus-associated non-Hodgkin lymphomas: the endless history

Hepatitis C virus (HCV) is a global population problem due to its high prevalence worldwide. In the prognosis of patients with HCV not only hepatic but increasingly frequent of extrahepatic HCV manifestations, such as mixed cryoglobulinemia (MC) and non-Hodgkin's lymphoma (NHL), are important. The role of the HCV virus in the pathogenesis of lymphoproliferative diseases is confirmed by a large number of epidemiological studies, as well as by the effectiveness of antiviral therapy in patients with non-Hodgkin's lymphoma (NHL). The purpose of the review was to provide an overview of epidemiological and biological data explaining the role of HCV in the development of NHL. The review also discusses HCV-associated NHL treatment by the traditional antiviral therapy (interferon and ribavirin) and by the new direct antiviral agents.

Changes in miR-122 and Cholesterol Expression in Chronic Hepatitis C Patients after PegIFN-Alpha/Ribavirin Treatment

The hepatitis C virus (HCV) is known as a main etiological cause of chronic hepatitis. HCV infection disturbs cholesterol metabolism of the host, which is frequently observed in patients suffering from chronic hepatitis C (CHC). The course of viral infections remains under strict control of microRNA (miRNA). In the case of HCV, miR-122 exerts a positive effect on HCV replication in vitro. The purpose of this study was to investigate the impact of peginterferon alpha (pegIFN-α) and ribavirin treatments on the expression of miR-122 and the cholesterol level in the peripheral blood mononuclear cells (PBMCs) of CHC patients. We report here that the level of miR-122 expression in the PBMCs decreased after the antiviral treatment in comparison to the pretreated state. Simultaneously, the level of cholesterol in the PBMCs of CHC patients was higher six months following the treatment than it was pretreatment. Consequently, it seems that the decrease of miR-122 expression in the PBMCs of CHC patients is one of the antiviral effects connected with the pegIFN-alpha/ribavirin treatments.

Hepatitis C Virus Infection and Cholangiocarcinoma: An Insight into Epidemiologic Evidences and Hypothetical Mechanisms of Oncogenesis

Hepatitis C virus (HCV) infection is a global public health problem because it is a main cause of liver cirrhosis and hepatocellular carcinoma. This human oncogenic virus is also associated with the development of non-Hodgkin lymphoma and cholangiocarcinoma (CCA). The association between HCV infection and CCA has been examined in a number of epidemiologic studies. However, in vivo and in vitro results demonstrating the oncogenic mechanisms of HCV in CCA development and progression are insufficient. Here, we review the epidemiologic association of HCV and CCA and recent publications of studies of HCV infection of cholangiocytes and CCA cell lines as well as studies of viral infection performed with liver samples obtained from patients. In addition, we also discuss the preliminary results of in vitro assays of HCV protein expression in CCA cell lines. Finally, we discuss the hypothetical role of HCV infection in CCA development by induction of epithelial-mesenchymal transition and up-regulation of hedgehog signaling, and consequently biliary tree inflammation and liver fibrosis. Further studies are required to demonstrate these hypotheses and therefore to elucidate the mechanisms of HCV as a risk factor for CCA.

Quasispecies Changes with Distinctive Point Mutations in the Hepatitis C Virus Internal Ribosome Entry Site (IRES) Derived from PBMCs and Plasma

The 5' untranslated region (UTR) of the hepatitis C virus (HCV) genome contains the internal ribosome entry site (IRES), a highly conserved RNA structure essential for cap-independent translation of the viral polyprotein. HCV, apart from the liver, is thought to be associated with lymphocyte subpopulations of peripheral blood mononuclear cells (PBMCs), in lymph nodes and brain tissue. In this study, RT-PCR, cloning, and sequence analysis were employed to investigate the quasispecies nature of the 5'UTR following extraction of viral RNA from PBMCs and plasma of HCV infected individuals. The nucleotide variation between IRES-derived sequences from PBMCs and plasma indicated the existence of polymorphic sites within the IRES. HCV isolates had divergent variants with unique mutations particularly at positions 107, 204, and 243 of the IRES. Most of the PBMC-derived sequences contained an A-A-A variant at these positions. The mutations associated with the IRESes suggested the presence of unique quasispecies populations in PBMCs compared with plasma.

HCV replication in gastrointestinal mucosa: Potential extra-hepatic viral reservoir and possible role in HCV infection recurrence after liver transplantation

PURPOSE

Hepatitis C virus (HCV) predominantly infects hepatocytes, although it is known that receptors for viral entry are distributed on a wide array of target cells. Chronic HCV infection is indeed characterized by multiple non-liver manifestations, suggesting a more complex HCV tropism extended to extrahepatic tissues and remains to be fully elucidated. In this study, we investigated the gastrointestinal mucosa (GIM) as a potential extrahepatic viral replication site and its contribution to HCV recurrence.

METHODS

We analyzed GIM biopsies from a cohort of 76 patients, 11 of which were HCV-negative and 65 HCV-positive. Of these, 54 biopsies were from liver-transplanted patients. In 29 cases, we were able to investigate gastrointestinal biopsies from the same patient before and after transplant. To evaluate the presence of HCV, we looked for viral antigens and genome RNA, whilst to assess viral replicative activity, we searched for the replicative intermediate minus-strand RNA. We studied the genetic diversity and the phylogenetic relationship of HCV quasispecies from plasma, liver and gastrointestinal mucosa of HCV-liver-transplanted patients in order to assess HCV compartmentalization and possible contribution of gastrointestinal variants to liver re-infection after transplantation.

RESULTS

Here we show that HCV infects and replicates in the cells of the GIM and that the favorite hosts were mostly enteroendocrine cells. Interestingly, we observed compartmentalization of the HCV quasispecies present in the gastrointestinal mucosa compared to other tissues of the same patient. Moreover, the phylogenetic analysis revealed a high similarity between HCV variants detected in gastrointestinal mucosa and those present in the re-infected graft.

CONCLUSIONS

Our results demonstrated that the gastrointestinal mucosa might be considered as an extrahepatic reservoir of HCV and that could contribute to viral recurrence. Moreover, the finding that HCV infects and replicates in neuroendocrine cells opens new perspectives on the role of these cells in the natural history of HCV infection.

Cerebral microglia activation in hepatitis C virus infection correlates to cognitive dysfunction

Hepatitis C virus (HCV) infection may induce chronic fatigue and cognitive dysfunction. Virus replication was proven within the brain and HCV-positive cells were identified as microglia and astrocytes. We hypothesized that cerebral dysfunction in HCV-afflicted patients is associated with microglia activation. Microglia activation was assessed in vivo in 22 patients with chronic HCV infection compared to six healthy controls using [(11) C]-PK11195 Positron Emission Tomography (PET) combined with magnetic resonance tomography for anatomical localization. Patients were subdivided with regard to their PCR status, Fatigue Impact Scale score (FIS) and attention test sum score (ATS). A total of 12 patients (54.5%) were HCV PCR positive [of which 7 (58.3%) had an abnormal FIS and 7 (58.3%) an abnormal ATS], 10 patients (45.5%) were HCV PCR negative (5 (50%) each with an abnormal FIS or ATS). Patients without attention deficits showed a significantly higher accumulation of [(11) C]-PK11195 in the putamen (P = 0.05), caudate nucleus (P = 0.03) and thalamus (P = 0.04) compared to controls. Patients with and without fatigue did not differ significantly with regard to their specific tracer binding in positron emission tomography. Preserved cognitive function was associated with significantly increased microglia activation with predominance in the basal ganglia. This indicates a probably neuroprotective effect of microglia activation in HCV-infected patients.

Hepatitis C virus long-term persistence in peripheral blood mononuclear cells in patients with haemophilia. Detection of occult genotype 1

Peripheral blood mononuclear cells (PBMC) from chronic hepatitis C virus-infected persons can harbour viral variants that are not detected in plasma samples. We explored the presence and persistence of HCV genotypes in plasma and PBMC cultures from 25 HCV-monoinfected and 25 HIV/HCV-coinfected patients with haemophilia. Cell cultures were performed at different time points between 1993 and 2010-2011, and the HCV genome was examined in culture supernatants. Sequential plasma samples were studied during the same time period. Analysing sequential plasma samples, 21% of patients had mixed-genotype infections, while 50% had mixed infections determined from PBMC culture supernatants. HIV coinfection was significantly associated with the presence of mixed infections (OR = 4.57, P = 0.02; 95% CI = 1.38-15.1). In our previous study, genotype 1 was found in 72% of 288 patients of this cohort. Similar results were obtained with the sequential plasma samples included in this study, 69% had genotype 1. However, when taking into account plasma samples and the results from PBMC supernatants, genotype 1 was identified in 94% of the population. The PBMC-associated variants persisted for 10 years in some subjects, emphasizing their role as long-term reservoirs. The presence of genotype 1 in PBMC may be associated with therapeutic failure and should not be disregarded when treating haemophilic patients who have been infected by contaminated factor concentrates. The clinical implications of persistent lymphotropic HCV variants deserve further examination among multiple exposed groups of HCV-infected patients.

New evidence of replication of hepatitis C virus in short-term peripheral blood mononuclear cell cultures

BACKGROUND

Even though hepatocytes are the main site for hepatitis C virus (HCV) replication, peripheral blood mononuclear cells (PBMC) have also been proposed as a suitable site for HCV replication. However, this issue still remains under discussion. We have previously developed an innovative system where HCV-RNA can be recovered during PBMC culture from HCV infected patients. Thus, the aim of this work was to use this novel approach in order to observe the evolution and replication of HCV genotype 1b in the PBMC of an HIV-HCV coinfected patient.

METHODS

HCV-RNA was extracted from serum, uncultured PBMC and PBMC culture at day 6, 20 and 33. The evolutionary analysis was performed using the direct sequences of three viral regions: 5'UTR, E2 and NS5A. Additionally, E2 region was cloned in order to extend the evolutive analysis.

RESULTS

In the present work, the molecular characterization of HCV along the culture showed a clear dynamic evolving process with the appearance of several nucleotide or amino acid changes in the three regions analyzed. Furthermore, the population analysis of E2 clones showed emerging and loss of lineages which indicate the fast evolutive dynamics of this system.

CONCLUSIONS

Since evolution can take place only if the virus is replicating in the culture, this finding constitutes an important evidence of viral replication in PBMC. Moreover, this extrahepatic compartment could be very important due to the presence of distinctive variants that could be responsible for resistance to treatment, viral pathogenesis and other clinical implications.

Investigation of biomarkers in peripheral blood cells of Pakistani chronic HCV patients with genotype 3a: an assessment of HCV-induced pathogenesis

ABSTRACT: 

Aim: The main objective of the current study was to measure the mRNA expression of potent genes involved in oxidative stress, fibrosis and insulin resistance in chronic HCV patients using peripheral white blood cells. Materials & methods: A total of 50 individuals were selected for this study, including 40 chronic HCV patients and ten healthy individuals. RNA was extracted from human peripheral white blood cells of chronic HCV-infected patients and healthy individuals. Transcript analysis of selected genes was performed using real-time PCR. Results: A significant increase was observed in the mRNA expression of Nox4, TGF-β, TNF-α and collagen, while a significant decrease was observed in mRNA expression of Cu/Zn SOD and IL-10. However, there was no significant change found in mRNA expression of SOCS3 and SOCS7 level. Conclusion: The current study confirms the significant expression of different genes in peripheral white blood cells of chronic HCV patients. This could be an easy, cost-efficient approach for the assessment of HCV-induced pathologies at extrahepatic sites, which could be further validated in comparison with liver tissue biopsies.

Direct effects of hepatitis C virus on the lymphoid cells

It has been reported that the direct binding of hepatitis C virus (HCV) and/or the replication of HCV in the extrahepatic organs and, especially, lymphoid cells, might affect the pathogenesis of extrahepatic diseases with HCV infection. More than one decade ago, several reports described the existence of HCV-RNA in peripheral blood mononuclear cells. Moreover, many reports describing the existence of HCV in B lymphocytes and B cell lymphoma have been published. In addition to B lymphocytes, it was reported that HCV replication could be detected in T lymphocytes and T cell lines. Among the extrahepatic diseases with HCV infection, mixed cryoglobulinemia-related diseases and autoimmune-related diseases are important for understanding the immunopathogensis of HCV persistent infection. Moreover, HCV persistent infection can cause malignant lymphoma. The biological significance of lymphotropic HCV has not yet become clear. However, several candidates have been considered for a long time. One is that lymphotropic HCV is an HCV reservoir that might contribute to the recurrence of HCV infection and difficult-to-treat disease status. The other important issue is the carcinogenesis of the lymphoid cells and disturbances of the immune responses. Therefore, the extrahepatic diseases might be induced by direct interaction between HCV and lymphoid cells. In this article, we summarize various studies showing the direct effect of HCV on lymphoid cells and discuss the biological significance of lymphotropic HCV.

Differential expression of candidate virus receptors in human T lymphocytes prone or resistant to infection with patient-derived hepatitis C virus

Accumulated evidence implies that hepatitis C virus (HCV) infects not only the liver but also the immune system. A lymphocyte-specific CD5 molecule was recently identified as essential for infection of T cells with native, patient-derived HCV. To assess whether the proposed hepatocyte receptors may also contribute to HCV lymphotropism, expression of scavenger receptor-class B type 1 (SR-B1), claudin-1 (CLDN-1), claudin-6 (CLDN-6), occludin (OCLN), CD5 and CD81 was examined by real-time RT-PCR and the respective proteins quantified by immunoblotting in HCV-prone and resistant T cell lines, peripheral blood mononuclear cells (PBMC), primary T cells and their subsets, and compared to hepatoma Huh7.5 and HepG2 cells. SR-B1 protein was found in T and hepatoma cell lines but not in PBMC or primary T lymphocytes, CLDN-1 in HCV-resistant PM1 T cell line and hepatoma cells only, while CLDN-6 equally in the cells investigated. OCLN protein occurred in HCV-susceptible Molt4 and Jurkat T cells and its traces in primary T cells, but not in PBMC. CD5 was displayed by HCV-prone T cell lines, primary T cells and PBMC, but not by non-susceptible T and hepatoma cell lines, while CD81 in all cell types except HepG2. Knocking-down OCLN in virus-prone T cell line inhibited HCV infection, while de novo infection downregulated OCLN and CD81, and upregulated CD5 without modifying SR-B1 expression. Overall, while no association between SR-B1, CLDN-1 or CLDN-6 and the susceptibility to HCV was found, CD5 and CD81 expression coincided with virus lymphotropism and that of OCLN with permissiveness of T cell lines but unlikely primary T cells. This study narrowed the range of factors potentially utilized by HCV to infect T lymphocytes amongst those uncovered using laboratory HCV and Huh7.5 cells. Together with the demonstrated role for CD5 in HCV lymphotropism, the findings indicate that virus utilizes different molecules to enter hepatocytes and lymphocytes.

Genetic variations in host IL28B links to the detection of peripheral blood mononuclear cells-associated hepatitis C virus RNA in chronically infected patients

Hepatitis C virus (HCV) is mainly hepatotropic; however, several reports document the presence of genomic viral RNA in extrahepatic sites including peripheral blood mononuclear cells (PBMCs). In this study, the presence of HCV RNA was initially evaluated in the plasma and peripheral blood mononuclear cells (PBMCs) of 53 HCV-infected patients who were treated per protocol. PBMC-associated HCV RNA was detectable in 79% of patients. Early virological response to combined pegylated interferon-α (PegIFN) and ribavirin (RBV) therapy in patients with undetectable levels of PBMCs-associated HCV RNA was 100%, while it was 60% (P = 0.003) in those who had detectable levels of PBMC-associated HCV RNA. A sustained virological response was observed in 35% of patients with detectable PBMC-associated HCV RNA, but was 70% in patients with undetectable levels of PBMC-associated HCV RNA (P = 0.07). In a multivariate analysis incorporating parameters such as HCV genotype, viral load, presence of cirrhosis and absence of PBMC-associated HCV RNA, a significant relationship was observed between the detection of PBMC-associated HCV RNA and the sustained virological response (OR 19.4, 95% CI: 2.1-486.2, P = 0.0061). The association between single nucleotide polymorphism (SNP) in IL28B, known predictor of antiviral therapy outcome, and the occurrence of HCV RNA in PBMC in 84 chronically infected patients was then evaluated. Results suggest that the presence of a G allele in rs8099917, known to associate to a poor response to PegIFN/RBV therapy, also predicts an increased association of HCV RNA with PBMC (OR: 3.564; 95% CI: 1.114-11.40, P = 0.0437).

Correlates and characteristics of hepatitis C virus-specific T-cell immunity in exposed uninfected high-risk prison inmates

Some hepatitis C (HCV)-uninfected, high-risk individuals have HCV-specific cellular immunity without viraemia or seroconversion. The characteristics of these responses and the risk behavioural associations were studied in 94 subjects in a prospective cohort of recently seronegative prisoners reporting injecting drug use (IDU). Detailed behavioural data were collected. HCV antibody and PCR testing were performed. ELISpot assays for HCV-induced interferon (IFN)-γ and interleukin (IL)-2 production by T lymphocytes, as well as multiplex in vitro cytokine production assays, were performed. Seventy-eight subjects remained antibody and PCR negative and 16 seroconverted. Of the seronegative group, 22 (28%) had IFN-γ ELISpot responses in comparison with 13 of the 16 seroconverters (82%). This seronegative immune status was associated positively with injecting anabolic steroids and negatively with a recent break from IDU. The IFN-γ ELISpot responses involved both CD4 and CD8 T lymphocytes and were comparable in magnitude, but narrower in specificity, in uninfected subjects than in seroconverters. A subset of seronegative subjects had HCV-induced cytokine production patterns comparable with the seroconverters with increased production of IFN-γ, IL-2 and tumour necrosis factor (TNF)-α and reduced IL-10 in response to nonstructural peptides. In conclusion, comparable patterns of HCV-specific cellular immunity are found in recently infected subjects and in a minority of high-risk, uninfected subjects. Further characterization of these responses and their protective efficacy will inform HCV vaccine development.

Investigation of residual hepatitis C virus in presumed recovered subjects

Recent studies have found hepatitis C virus (HCV) RNA in peripheral blood mononuclear cells (PBMCs) of the majority of presumed recovered subjects. We investigated this unexpected finding using samples from patients whose HCV RNA and anti-HCV status had been serially confirmed. HCV RNA was detected in PBMCs from 66 of 67 chronic HCV carriers. Subpopulation analysis revealed that the viral load (log copies/10(6) cells) in B cells (4.14 ± 0.71) was higher than in total PBMCs (3.62 ± 0.71; P < 0.05), T cells (1.67 ± 0.88; P < 0.05), and non-B/T cells (2.48 ± 1.15; P < 0.05). HCV negative-strand RNA was not detected in PBMCs from any of 25 chronically infected patients. No residual viral RNA was detected in total PBMCs or plasma of 59 presumed recovered subjects (11 spontaneous and 48 treatment induced) using nested real-time polymerase chain reaction with a detection limit of 2 copies/μg RNA (from ≈ 1 × 10(6) cells). PBMCs from 2 healthy HCV-negative blood donors became HCV RNA positive, with B-cell predominance, when mixed in vitro with HCV RNA-positive plasma, thus passively mimicking cells from chronic HCV carriers. No residual HCV was detected in liver or other tissues from 2 spontaneously recovered chimpanzees.

CONCLUSION

(1) HCV RNA was detected in PBMCs of most chronic HCV carriers and was predominant in the B-cell subpopulation; (2) HCV detected in PBMCs was in a nonreplicative form; (3) HCV passively adsorbed to PBMCs of healthy controls in vitro, becoming indistinguishable from PBMCs of chronic HCV carriers; and (4) residual HCV was not detected in plasma or PBMCs of any spontaneous or treatment-recovered subjects or in chimpanzee liver, suggesting that the classic pattern of recovery from HCV infection is generally equivalent to viral eradication.

Biological significance of HCV in various kinds of lymphoid cells

It has been reported that HCV can infect not only hepatocytes but also various kinds of lymphoid cells. Although many reports have described the biological significance of lymphotropic HCV, the issue remains controversial since the target lymphoid cells might have various kinds of functions in the immune system. One of the important roles of lymphoid cells in HCV replication is being a reservoir of HCV. Several groups described the detection of HCV-RNA in lymphoid cells after HCV eradication in plasma. Another important role of lymphotropic HCV is that it acts as a carcinogenic agent and induces immune dysfunction. In this paper, we summarize the reports regarding the biological significance of lymphotropic HCV in representative lymphoid cells.

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 protects human B lymphocytes from Fas-mediated apoptosis via E2-CD81 engagement

HCV infection is often associated with B-cell regulatory control disturbance and delayed appearance of neutralizing antibodies. CD81 is a cellular receptor for HCV and can bind to HCV envelope protein 2 (E2). CD81 also participates to form a B cell costimulatory complex. To investigate whether HCV influences B cell activation and immune function through E2 -CD81 engagement, here, human Burkitt's lymphoma cell line Raji cells and primary human B lymphocytes (PHB) were treated with HCV E2 protein and cell culture produced HCV particles (HCVcc), and then the related cell phenotypes were assayed. The results showed that both E2 and HCVcc triggered phosphorylation of IκBα, enhanced the expression of anti-apoptosis Bcl-2 family proteins, and protected Raji cells and PHB cells from Fas-mediated death. In addition, both E2 protein and HCVcc increased the expression of costimulatory molecules CD80, CD86 and CD81 itself, and decreased the expression of complement receptor CD21. The effects were dependent on E2-CD81 interaction on the cell surface, since CD81-silenced Raji cells did not respond to both treatments; and an E2 mutant that lose the CD81 binding activity, could not trigger the responses of both Raji cells and PHB cells. The effects were not associated with HCV replication in cells, for HCV pseudoparticle (HCVpp) and HCVcc failed to infect Raji cells. Hence, E2-CD81 engagement may contribute to HCV-associated B cell lymphoproliferative disorders and insufficient neutralizing antibody production.

Modulation of IL-2 expression after uptake of hepatitis C virus non-enveloped capsid-like particles: the role of p38 kinase

Hepatitis C virus (HCV) has been shown to actively replicate in cells of the immune system, altering both their function and cytokine expression. Naked nucleocapsids have been reported in the serum of infected patients. We investigated interference of recombinant non-enveloped capsid-like particles with signaling pathways in T cells. HCV non-enveloped particles (HCVne) internalization was verified in Jurkat and Hut 78 T cells, as well as primary human peripheral blood and intrahepatic mononuclear cells. HCVne uptake leads to activation of the MAPKs-p38 signaling pathway. Using specific phosphoantibodies, signaling pathways inhibitors, and chemical agents, it was demonstrated that p38 activation in T cells correlated with IL-2 transcriptional activation and was accompanied by a parallel increase of IL-2 cytokine secretion. c-fos and egr-1, two transcription factors, essential for IL-2 promoter activity, were also found to be elevated. We propose that HCVne uptake by T lymphocytes results in increased MAPKs-p38 activity and IL-2 expression, thus altering the host immune response.

Lymphotropic HCV strain can infect human primary naïve CD4+ cells and affect their proliferation and IFN-γ secretion activity

BACKGROUND

Lymphotropic hepatitis C virus (HCV) infection of B and T cells might play an important role in the pathogenesis of hepatitis C. Recently, we showed that a lymphotropic HCV (SB strain) could infect established T-cell lines and B-cell lines. However, whether HCV replication interferes with cell proliferation and function in primary T lymphocytes is still unclear.

AIM

The aim of this study was to analyze whether HCV replication in primary T lymphocytes affected their development, proliferation, and Th1 commitment.

METHODS

SB strain cell culture supernatant (2 × 10(4) copies/ml HCV) was used to infect several kinds of primary lymphocyte subsets. Mock, UV-irradiated SB-HCV, JFH-1 strain, and JFH-1 NS5B mutant, which could not replicate in T cells, were included as negative controls. Carboxyfluorescein succinimidyl ester (CFSE) and CD45RA double staining was used to evaluate the proliferative activity of CD4(+)CD45RA(+)CD45RO(-) naïve CD4(+) cells. Interferon (IFN)-γ and interleukin (IL)-10 secretion assays magnetic cell sorting (MACS) were carried out.

RESULTS

Negative strand HCV RNA was detected in CD4(+), CD14(+), and CD19(+) cells. Among CD4(+) cells, CD4(+)CD45RA(+)RO(-) cells (naïve CD4(+) cells) were most susceptible to replication of the SB strain. The levels of CFSE and CD45RA expression gradually declined during cell division in uninfected cells, while HCV-infected naïve CD4(+) cells expressed higher levels of CFSE and CD45RA than Mock or UV-SB infected naïve CD4(+) cells. Moreover, the production of IFN-γ was significantly suppressed in SB-infected naïve CD4(+) cells.

CONCLUSIONS

Lymphotropic HCV replication suppressed proliferation and development, including that towards Th1 commitment, in human primary naïve CD4(+) cells.

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.

Hepatitis C virus quasispecies in plasma and peripheral blood mononuclear cells of treatment naïve chronically infected patients

Peripheral blood mononuclear cells (PBMCs) from 45 treatment naïve, HIV-negative, chronically hepatitis C virus (HCV)-infected patients were analyzed for the presence of HCV RNA. Viral RNA was detected in 73% of the studied patients. Single-strand conformation polymorphism assays and sequence analysis of the HCV 5'untranslated regions amplified from RNA recovered from both Plasma and PBMCs suggested virus compartmentalization in 57.6% of patients studied. In summary, our study presents evidence that HCV RNA can be found in PBMCs of treatment naïve chronically infected patients that are not immunocompromised or co-infected with the human immunodeficiency virus.

Mevalonate pathway modulation is associated with hepatitis C virus RNA presence in peripheral blood mononuclear cells

Peripheral blood mononuclear cells (PBMC) constitute the main extrahepatic reservoir of hepatitis C virus (HCV). Lipid metabolism of host seems to play important role in HCV infection. The relationship between HCV presence in PBMC and the expression of mevalonate pathway has not been elucidated. The aim of this study was to investigate the association between mevalonate pathway and HCV RNA presence in PBMC after anti-HCV treatment. 67 serum and corresponding PBMC samples were collected from patients at the end of interferon alpha and ribavirin treatment. Serum total cholesterol, HDL-C and LDL-C fractions, triglycerides, as well as intracellular cholesterol and expression level of HMG-CoA reductase, geranylgeranyl pyrophosphate synthase in PBMC were measured and matched for the HCV RNA presence or absence in sera/PBMC. HCV RNA elimination from sera and PBMC was associated with higher serum cholesterol (118.5mg/dL) and LDL-C (66.42mg/dL) levels, compared to the group, where HCV RNA was detected only in PBMC (100.94 and 53.22mg/dL) or the group, where HCV RNA was found in both sera and PBMC (86.79 and 43.79mg/dL) after treatment. Increased expression of geranylgeranyl pyrophosphate synthase was found in the majority of PBMC samples that harbored HCV RNA after elimination of HCV RNA from sera. The expression of mevalonate pathway after antiviral treatment seems to be modulated depending on HCV RNA status in peripheral blood mononuclear cells.

Evidence of hepatitis C virus-specific interferon gamma-positive T cells in health care workers in an infectious disease department

BACKGROUND

Few studies are available on possible hepatitis C virus (HCV)-specific T-cell immune response in health care workers (HCWs) involved in the care of patients with HCV infection. We aimed to investigate whether a HCV-specific interferon (IFN)-gamma T-cell response, known to be involved in infection resolution, was present in those HCWs involved in the management of patients with persistent HCV infection.

METHODS

Our study involved 30 subjects, classified as group A (20 consecutive patients, 16 males and 4 females, with histologically proven chronic hepatitis), or group B (10 HCWs, 7 males and 3 females, with at least 7 years of health care experience and HCV-RNA and anti-HCV negative). As a control group, we used 10 blood samples from healthy donors at a blood donor center (group C). HCV-RNA was measured by real-time polymerase chain reaction. Blood samples (at least 35 mL) were collected from all group A and group B subjects in our hospital. Specific IFN-gamma was stimulated with HCV pool peptides (core, 2 microg/mL), with influenza Mp peptides used as a positive control.

RESULTS

Levels of HCV-specific IFN-gamma-positive cells were higher in the HCWs (group B) compared with the infected patients (group A) and healthy blood donors (group C) (Mann-Whitney U test, P < .001).

CONCLUSION

A clinically silent persistent exposure to HCV, through some as-yet undetermined mechanism, may induce a virus-specific IFN-gamma-producing CD8(+) T-cell response in healthy aviremic HCWs. This finding suggests that possible unapparent parenteral routes may stimulate host defenses with no evidence of hepatitis.

Hepatitis C virus infection of T cells inhibits proliferation and enhances fas-mediated apoptosis by down-regulating the expression of CD44 splicing variant 6

BACKGROUND

A lymphotropic hepatitis C virus strain (HCV, SB strain, hereafter "SB-HCV") has been shown to infect established T cell lines (Molt-4 and Jurkat) and primary human naive CD4(+) T cells. During T cell development and activation, transient expression of CD44 splicing variant 6 (CD44v6) plays a significant role.

METHODS

SB-HCV was used to infect Molt-4 cells, and their cellular proliferation and CD44 expression was examined.

RESULTS

SB-HCV-infected Molt-4 cells expressed a significantly lower level of the CD44v6 isoform. The infected cells could be divided into 2 carboxyfluorescein succinimidyl ester (CFSE) groups, CFSE-high (indicating low proliferation activity; 34.2% of the cells) and CFSE-low (indicating high proliferation activity; 62.5% of the cells), whereas uninfected cells consisted of only a CFSE-low population. Of the CFSE-high cells, 82.4% were positive for the HCV protein NS5A, whereas only 1.2% of the CFSE-low cells were positive for this protein. Among the HCV proteins, NS5A alone caused the down-regulation of CD44v6 expression. After cells were stimulated with phorbol myristate acetate, the amount of phosphorylated mitogen-activated protein (MAP) kinase was significantly reduced in CFSE-high, SB-HCV-infected Molt-4 cells. After Fas ligand stimulation, SB-HCV-infected Molt-4 cells had increased cleavage of caspase 8 and 3 and enhanced apoptosis, compared with the rates of cleavage and apoptosis in control groups, indicating that SB-HCV infection increased Fas-mediated apoptosis.

CONCLUSION

HCV replication in T cells suppresses cellular proliferation and enhances susceptibility to Fas signaling by inhibiting CD44v6 signaling and expression.

Therapy with interferon-alpha and ribavirin for chronic hepatitis C virus infection upregulates membrane HLA-ABC, CD86, and CD28 on peripheral blood mononuclear cells

Multiple interferon-stimulated genes (ISGs) involving T-cell activation are upregulated during initial interferon-alpha-based therapy for chronic hepatitis C virus (HCV) infection. However, the long-term impact on therapeutic outcome in patients remains unknown. In this study, the effects of anti-HCV therapy on the surface expression of HLA-ABC, CD86, and CD28 were longitudinally assessed. These proteins are integral membrane receptors of antigen presentation and triggering of costimulatory signals for activating CD8+ T cells. Peripheral blood mononuclear cells were collected at baseline and post-treatment for 1 day, and 2, 4, 12, and 24 weeks, respectively. This treatment led to a time-related elevation of membrane levels of HLA-ABC and CD86 on B-cells and monocytes in patients with a sustained response (n = 23), but not in those without (n = 8). Meanwhile, upregulation of CD28 on CD4+ and CD8+ T cells was comparable in both groups of sustained responders and non-responders. Steady increases in the B cells' surface and intracellular HLA-ABC were observed, thus, the surface-to-intracellular ratios did not alter over the period of treatment. Furthermore, multivariate analysis shows that increased HLA-ABC on monocytes by week 12 correlates significantly with sustained response (P = 0.033). In conclusion, differential modulation of T-cell activation ISGs, such as HLA-ABC and CD86 might correlate with the outcome of interferon-alpha-based therapy in chronic hepatitis C patients.

Clearance of hepatitis C virus RNA from the peripheral blood mononuclear cells of blood donors who spontaneously or therapeutically control their plasma viremia

We determined whether hepatitis C virus (HCV) RNA could be detected associated with peripheral blood mononuclear cells (PBMC) of seropositive blood donors who had spontaneously or therapeutically cleared their plasma viremia. Blood donor plasma viremia status was first determined with a highly sensitive transcription-mediated amplification (TMA) test performed in duplicate assays. PBMC from 69 aviremic and 56 viremic blood donors were then analyzed for the presence of HCV RNA with TMA adapted to detect viral RNA in PBMC and with a reverse transcription-nested polymerase chain reaction assay. PBMC-associated HCV RNA was detected in none of the 69 aviremic donors, including all 6 subjects with a sustained viral response following antiviral therapy. PBMC-associated HCV RNA was detected in 43 of the 56 viremic donors. The 13 viremic donors with no detectable PBMC-associated HCV RNA all had very low viral loads (6 positive only in 1 of 2 duplicate plasma TMA assays, 6 with viral loads below 100 HCV RNA copies/mL, and 1 with a viremia of 2700 HCV RNA copies/mL). The absence of detectable PBMC HCV RNA detection in all 69 aviremic donors reported here contrasts with prior studies, possibly as a result of the higher sensitivity of the TMA assay used to test for plasma viremia.

CONCLUSION

Our results indicate that PBMC are unlikely to serve as a long-lived reservoir of HCV in aviremic subjects.

Antibody-dependent enhancement of hepatitis C virus infection

Hepatitis C virus (HCV) often causes a persistent infection associated with hypergammaglobulinemia, high levels of antiviral antibody and circulating immune complexes, and immune complex disease. We previously reported that only a limited neutralizing activity to vesicular stomatitis virus or HCV pseudotype is generated in animals immunized with recombinant HCV envelope proteins and chronically infected HCV patient sera. Interestingly, when some of these neutralizing sera were diluted into a range of concentrations below those that reduced virus plaque number, an increase in pseudotype plaque formation was observed. Purified HCV E2-specific human monoclonal antibodies were used to further verify the specificity of this enhancement, and one- to twofold increases were apparent on permissive Huh-7 cells. The enhancement of HCV pseudotype titer could be inhibited by the addition of a Fc-specific anti-human immunoglobulin G Fab fragment to the virus-antibody mixture prior to infection. Treatment of cells with antibody to Fc receptor I (FcRI) or FcRII, but not FcRIII, also led to an inhibition of pseudotype titer enhancement in an additive manner. Human lymphoblastoid cell line (Raji), a poor host for HCV pseudotype infection, exhibited a four- to sixfold enhancement of pseudotype-mediated cell death upon incubation with antibody at nonneutralizing concentrations. A similar enhancement of cell culture-grown HCV infectivity by a human monoclonal antibody was also observed. Taken together, antibodies to viral epitopes enhancing HCV infection need to be taken into consideration for pathogenesis and in the development of an effective vaccine.

Hepatitis C virus lymphotropism: lessons from a decade of studies

The possibility that HCV infects lymphoid cells has been widely discussed. Evidence in favor of HCV tropism for lymphoid cells derives from a series of data including: (1) the higher sensitivity of testing HCVRNA in PBMC than in serum or plasma samples, with possible detection of HCV RNA-positive PBMC in the absence of HCV viremia; (2) short-term cultures of PBMC which yield a significant increase in the amount of viral RNA on stimulation by mitogens; (3) results of "in situ" methods (i.e. in situ hybridization, immunofluorescence); (4) efficient infection of lymphoid cell lines or PBMC from normal individuals; (5) the persistence of HCV RNA in PBMC obtained from HCV-positive subjects and injected into SCID mice; (6) the long-term persistence of HCV RNA in PBMC in spite of HCV RNA negativity of serum and liver in sustained responder patients after therapy. The principal criticisms concerning effective HCV infection of lymphoid cells arise from technical difficulty in identifying HCV RNA replicative intermediate in these elements. Conflicting data may also result from differences in PBMC infection by different genotypes, samples taken at different stages in the disease process and differences in the sensitivity of detection methods, as well as low replication levels and/or proportion of infected PBMC. Interesting available data about HCV lymphotropism, which is possibly important in influencing the natural history of infection, include: (1) possible preferential viral tropism for specific PBMC subsets; (2) different lymphotropism of different viral strains; (3) selection of distinctive viral strains; (4) identification of putative HCV cell receptors; (5) association between determination of HCV lymphatic infection and t(14; 18) translocation. The clinical correlates of HCV lymphotropism are potentially very numerous, including, first, its role in determining HCV-related lymphoproliferative disorders.

Impact of hepatitis C on HIV progression in adults with alcohol problems

BACKGROUND

Coinfection of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) is a substantial medical and public health concern due to its increasing prevalence and complex patient management. Alcohol use may worsen HCV-related liver disease and interfere with adherence to antiretroviral therapy (ART) and medical care. We therefore studied the association between HCV infection and markers of HIV disease progression in adults with alcohol problems.

METHODS

This is a longitudinal study of 396 HIV-infected persons with alcohol problems, 199 (50%) of whom were coinfected with HCV (positive HCV RNA test). CD4 cell counts and HIV RNA levels were assessed at baseline and then every 6 months for up to 42 months. Hepatitis C virus RNA status was determined at study enrollment. We examined the relationship between HCV infection and laboratory markers of HIV progression (CD4 cell count and log10 HIV RNA) by fitting multivariable longitudinal regression models for each outcome.

RESULTS

Among subjects who were adherent to ART, the presence of HCV infection was associated with a lower CD4 cell count (adjusted mean difference -46.0 cells/microL, p=0.03). There was no association observed between HCV infection and CD4 cell count among those not adherent to ART or those not taking ART. No significant association was observed between HCV infection and HIV RNA regardless of ART status.

CONCLUSIONS

Hepatitis C virus infection has an adverse effect on CD4 cell count in patients with alcohol problems who are adherent to ART. Addressing HCV coinfection among these patients may confer additional immunologic benefit for this patient population.

Hepatitis C virus infects T cells and affects interferon-gamma signaling in T cell lines

It has been reported that hepatitis C virus (HCV) may infect and replicate in human T cells, particularly in perihepatic lymph nodes, but the extent and consequence of T-cell infection in patients is unclear. This study is conducted to characterize the parameters and functional consequences of HCV infection in T lymphocytes. By using a lymphotropic HCV strain, we showed that HCV could infect T cell lines (Molt-4 and Jurkat cells) in vitro. Both positive- and negative-strand HCV RNA were detected for several weeks after infection. Viral proteins could also be detected by immunofluorescence studies. Moreover, infectious HCV particles were produced from Molt-4 cell cultures, and could be used to infect naïve T cell lines. HCV could also infect human primary CD4+ T cells, particularly naïve (CD45RA+CD45RO-) CD4+ cells, in culture. The amounts of STAT-1 and phosphorylated STAT-1 proteins in the infected Molt-4 cells were significantly less than those in uninfected cultures, suggesting the possibility of defect in interferon-gamma signaling. Indeed, T-bet and STAT-1 mRNA levels after interferon-gamma stimulation in infected Molt-4 were suppressed. In conclusion, HCV could infect and transiently replicate in T cells and that HCV replication suppressed the IFN-gamma/STAT-1/T-bet signaling due to the reduction of STAT-1 and inhibition of its activation (phosphorylation).

Differential dysfunction in dendritic cell subsets during chronic HCV infection

Hepatitis C virus (HCV) infection is a leading cause of chronic liver disease with over 200 million individuals infected worldwide. The vast majority of acutely infected humans develop chronic infection, which is characterized by attenuated antiviral T-cell responses. The mechanisms leading to such attenuation/suppression are poorly understood. It has been proposed that dysfunction of antigen-presenting cells (APC) may underlie the downregulation of antiviral immune responses. However, studies using bulk or in vitro-derived APC populations have resulted in conflicting reports. In this study, we evaluated the functional and immunophenotypic features of ex vivo-purified dendritic cell (DC) subsets during chronic HCV infection. We found that plasmacytoid DC (PDC) from HCV-infected patients (HCV-PDC) showed a striking deficit in IFN-alpha production in response to CpG stimulation. In addition, we found that myeloid DC (MDC) from these patients showed a diminished capacity to induce a mixed lymphocyte response (MLR), correlating with lower levels of HLA-DR and CD86 expression and higher IL-10 production in response to poly-IC stimulation. In contrast, HCV-PDC showed increased ability to stimulate an MLR. Of note, within the HCV-PDC preparation, we noted a distinctly expanded DC subset that expressed some markers of MDC, but showed significantly lower HLA-DR and CD86 expression, suggesting an expansion of DC at an immature/intermediate stage of differentiation. Our studies demonstrate distinct and contrasting dysfunctional features in DC subsets and underscore the importance of evaluating APC subpopulations separately.

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.

Modulation of Interferon-Specific Gene Expression by Albumin-Interferon-α in Interferon-α-Experienced Patients with Chronic Hepatitis C

Albumin-interferon-α (alb-IFN) is a novel recombinant protein derived from IFN-α2b genetically fused to human albumin. The resulting single polypeptide combines in one molecule the antiviral properties of IFN-α with the long serum half-life of albumin. IFN-mediated biological responses stem from the engagement of IFN-α with its target receptor and subsequent modulation of IFN-specific gene (ISG) expression. To evaluate the pharmacodynamics of alb-IFN during the Phase I/II study conducted in patients with chronic hepatitis C (CHC) who had previously failed IFN-α-containing regimens, ISG induction was evaluated in peripheral blood and compared with antiviral response. Whole blood was obtained at day 0, day 7 and day 28 from 21 patients enrolled in the higher dose (500–900 μg) alb-IFN cohort, who received two injections on day 0 and day 14. Taqman real-time PCR was used to assess candidate ISG expression. There was sustained induction on day 7 and day 28 of the ISG's OAS1, IRF-7, IFI44 and IFI27. Although all patients showed a molecular response to alb-IFN, individual variability in pretreatment gene expression levels and fold of modulation during treatment was observed. At day 28, induction of OAS1, IFI44 and IRF7 showed pairwise correlation in individual patients ( P<0.05). Moreover, the induction of expression at day 28, and pretreatment levels of OAS1 and IFI44 correlated with hepatitis C virus RNA reduction at day 28 ( P<0.05). In conclusion, alb-IFN demonstrated robust induction of ISG that was consistent with the response associated with an IFN-α.

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.

Salient molecular features of hepatitis C virus revealed

Hepatitis C virus (HCV) is a positive strand RNA virus with a narrow host and tissue tropism. It ranks among the most significant of human pathogens, causing inflammation, scarring and cancer of the liver. Recent investigations have shed light on some of the salient molecular features of this virus. These include a requirement for CD81 (a tetraspanin transmembrane protein for viral entry), a novel mechanism for the initiation of RNA synthesis, phosphorylation of a viral protein in the regulation of RNA amplification and virus assembly and, finally, a viral protease suppressing activation of the innate immune response in infected cells.