The role of CCR5/CXCR3 expressing CD8+ cells in liver damage and viral control during persistent hepatitis C virus infection

Varied immune responses of HBV-specific B cells in patients undergoing pegylated interferon-alpha treatment for chronic hepatitis B

BACKGROUND & AIMS

The changes of HBV-specific B-cells in chronic hepatitis B (CHB) patients underwent pegylated interferon-alfa (PEG-IFNα) treatment and achieved functional cure remain unclear. We aimed to evaluate the alterations in HBV-specific B-cells during treatment and therefore explored the mechanism of functional recovery of HBsAg-specific B-cells.

METHODS

We included 39 nucleos(t)ide analogues-treated CHB patients who received sequential combination therapy with PEG-IFNα and 8 treatment-naive CHB patients. HBV-specific B-cells were characterized ex vivo using fluorescent labeled HBsAg and HBcAg. The frequency, phenotype, and subsets of HBV-specific B-cells and follicular helper T cells (Tfh-cells) were detected using flow cytometry. The functionality of HBV-specific B-cells was quantified through ELISpot assays.

RESULTS

During treatment, the fraction of activated memory B-cells (MBCs) among HBsAg-specific B-cells and the expression of IgG, CXCR3, and CD38 increased. Antibody-secretion capacity of HBsAg-specific B-cell was restored after treatment only in patients with a functional cure and it showed a positive correlation with serum hepatitis B surface antibody levels. The phenotype and function of HBsAg-specific B-cells differed between patients with and without functional cure. Patients with functional cure exhibited IgG+ classical MBCs and plasmablasts in HBsAg-specific B-cells. HBcAg-specific B-cells displayed both attenuated antibody secretion with reduced IgG expression and an IgM+ atypical type of MBCs after treatment, irrespective of with and without functional cure. The number of CD40L+ Tfh-cells increased after PEG-IFNα treatment and positively correlated with HBsAg-specific B-cell activation.

CONCLUSIONS

After PEG-IFNα treatment, HBsAg- and HBcAg-specific B-cells exhibit various changes in antibody secretion. Their functional differences are reflected in the alterations in phenotypes and subtypes. The presence of CD40L+ Tfh-cells is associated with the active recovery of HBsAg-specific B-cells.

IMPACT AND IMPLICATIONS

HBV-related complications and hepatocellular carcinoma remain the leading causes of mortality from chronic liver disease worldwide, and a cure is rarely achieved with antiviral therapies. Elucidating the immunological mechanisms underlying the functional cure of CHB patients offers a promising therapeutic strategy for viral clearance, such as therapeutic vaccine. We analyzed the alterations in HBV-specific B-cells in patients treated with PEG-IFNα and identified novel pathways for immunotherapeutic boosting of B cell immunity.

Plasma interferon-gamma-inducible-protein 10 level as a predictive factor of spontaneous hepatitis B surface antigen seroclearance in chronic hepatitis B patients

BACKGROUND AND AIM

Spontaneous seroclearance of hepatitis B surface antigen (HBsAg) is a rare event that occurs in patients that are chronically infected with the hepatitis B virus. As the functional cure and ultimate treatment endpoint of chronic hepatitis B (CHB), HBsAg seroclearance is an important milestone in the natural history of CHB and serves great clinical value. This study aims to identify host and viral factors associated with HBsAg seroclearance.

METHODS

This is a retrospective study carried out in the Queen Mary Hospital, Hong Kong. By analyzing the plasma retrieved from the serum archive (collected during 2011-2021) of 100 CHB patients attending the hospital's liver clinic, the longitudinal cytokine profiles between the HBsAg-losers and the control groups were compared.

RESULTS

Data revealed that plasma levels of IP-10 were significantly lower at 3-5 years prior to HBsAg seroclearance compared with patients who remained HBsAg positive (P < 0.05). Receiver operating characteristic curve analysis reveals that plasma IP-10 levels at multiple time points before HBsAg seroclearance return area under receivor-operating characteristic curve (AUC) greater than 0.7. Plasma IP-10 levels at 42.39 pg/mL produced an AUC = 0.723 with 74.0% sensitivity and 75.5% specificity to predict subsequent HBsAg seroclearance in the next 3-5 years. Low plasma IP-10 identified 91.4% patients with quantitative HBsAg < 100 IU/mL who would subsequently develop HBsAg seroclearance, compared with 37% with higher plasma IP-10 levels (P < 0.001).

CONCLUSIONS

Low plasma levels of IP-10 are associated with subsequent HBsAg seroclearance, suggesting potential clinical utilities of measurement of IP-10 in predicting HBsAg seroclearance, especially among patients with low HBsAg.

Chronic HCV infection promotes cytotoxicity in antigen-specific CD8+ T cells regardless of virus specificity

Introduction

Despite advancements in hepatitis C virus (HCV) infection treatment, HCV still represents a significant public health burden. Besides progressive hepatic damage, viral persistence has lasting effects on innate and adaptive immune responses. Lack of a complete understanding of the factors driving an effective HCV response contributes to the failure to develop a vaccine for prevention. This study advances the existing knowledge on HCV-specific CD8+ T cells and describes the impact of current or past HCV infection on CD8+ T cells specific for other viruses.

Methods

We used barcoded-dextramers to identify and sort CD8+ T cells specific for HCV, cytomegalovirus, and influenza, and characterized them using single-cell RNA sequencing technology. Our cohort included chronic (cHCV), spontaneously resolved (rHCV), and subjects undergoing direct-acting antiviral (DAA) therapy.

Results

We show that HCV-specific CD8+ T cells have cytotoxic features in patients with cHCV, which is progressively reduced with DAA therapy and persists 12 weeks after treatment completion. We also observe a shift in the CD8+ T cell phenotype on DAA treatment, with decreased effector memory and exhausted cell signatures. In rHCV, we also detected a smaller proportion of effector memory cells compared to cHCV. The proportion of CD8+ exhausted T cells in cHCV and rHCV subjects was comparable. Moreover, we also observed that non-HCV virus-specific CD8+ T cells exhibit robust cytotoxic traits during cHCV infection.

Discussion

Altogether, our findings suggest that cHCV infection promotes cytotoxicity in CD8+ T cells regardless of virus specificity. The immunological changes caused by cHCV infection in CD8+ T cells may contribute to worsening the ongoing hepatic damage caused by HCV infection or exacerbate the immune response to possible co-infections. Our data provide a resource to groups exploring the underlying mechanisms of HCV-specific T cell spontaneous and treatment-induced resolution to inform the development of effective vaccines against HCV infection.

IP-10 Interferes With the Antiviral Response of Direct-Acting Antiviral Agents for Hepatitis C Virus Infection

Background

Increased interferon (IFN)-gamma inducible protein-10 (IP-10) level has been shown to be associated with sustained virologic responses (SVRs) to pegylated interferon-alpha 2a/ribavirin-based therapy in patients with chronic hepatitis C (CHC). We investigated the relationship between IP-10 and treatment response in patients with CHC treated with direct-acting antiviral agents (DAAs) therapy.

Methods

We measured the dynamic changes of IP-10 in samples from 90 patients with CHC. The serum IP-10 levels, intrahepatic expressions of IP-10 mRNA, and protein were determined, respectively. For the in vitro experiments, the expression changes of IP-10 in hepatitis C virus (HCV)-replicating Huh-7 cells with or without non-structural protein 5A (NS5A) inhibitor were analyzed using real-time reverse transcription-polymerase chain reaction and Western blotting.

Results

Patients with chronic hepatitis C had increased baseline IP-10 levels, intrahepatic IP-10 mRNA, and protein expression. After initiating DAAs therapy, serum IP-10 levels decreased gradually in patients who achieved cure, whereas in patients who failed the therapy, IP-10 levels did not change significantly or recovered from the initial decline. Multivariate logistic regression analysis confirmed that baseline IP-10 level ≤ 450 pg/ml and decline >30% at 12 weeks independently predicted the SVR in patients with CHC who received DAAs. In vitro, the expression of IP-10 mRNA and protein in HCV-replicating Huh-7 cells increased significantly. However, such activities were downregulated by NS5A inhibitor, followed by the reduction of HCV RNA levels and a decline in IP-10 levels.

Conclusion

IP-10 interfered with HCV replication in hepatocytes and the dynamic decline in IP-10 levels during DAA treatment predicted the SVR in patients with CHC.

CCR5+ T-Cells Homed to the Liver Exhibit Inflammatory and Profibrogenic Signatures in Chronic HIV/HCV-Coinfected Patients

Liver fibrosis is accelerated in patients coinfected with hepatitis C virus and human immunodeficiency virus (HIV), compared with HCV monoinfected patients, although the underlying mechanisms are unknown. We hypothesize that T cells expressing the HIV co-receptor, chemokine receptor 5 (CCR5), preferentially migrate to the inflamed liver and contribute to enhanced fibrogenesis. We compared the peripheral and intrahepatic CCR5 expression on CD4+ and CD8+ T cells in 21 HIV/HCV-coinfected patients with 14 chronic HCV monoinfected patients. Using 12-color flow cytometry, phenotypic and functional characterization of CCR5+ and negative cells pre- and post-stimulation with HCV genotype specific overlapping pooled peptides was conducted. Patients with HIV/HCV coinfection had significantly more CD4+CCR5+ and CD8+CCR5+ T cells in the liver as compared with peripheral blood (p = 0.0001 for both). Compared with patients with HCV monoinfection, patients with HIV/HCV coinfection also had fewer peripheral CD4+CCR5+ and CD8+CCR5+ T cells (p = 0.02, p = 0.001 respectively), but more intrahepatic CD4+CCR5+ and CD8+CCR5+ cells (p = 0.0001 for both). Phenotypic analysis of CCR5+ sorted cells demonstrated an increased expression of markers of exhaustion, senescence, immune activation and liver homing (PD1, CD57, CD38, HLADR, and CXCR3). Post-stimulation with HCV peptides, CCR5+ T cells secreted more proinflammatory and profibrogenic cytokines and chemokines rather than antiviral cytokines. Phenotypic and functional analyses of CCR5+ T cells in HIV/HCV-coinfected patients revealed a pathogenic role for CCR5+ T cells in hepatic fibrogenesis. These cells are functionally proinflammatory, pro-fibrogenic and preferentially accumulate in liver, accelerating fibrosis. These findings suggest that targeting CCR5 may be a therapeutic strategy for be ameliorating liver fibrosis.

The CCR5 and CXCR3 Pathways in Hepatitis C Virus Liver Transplanted Recipients Treated by a Direct Antiviral Agent Regimen: Informative Kinetics Profiles

The CC5 and CXC3 chemokines (CK) pathways are involved in the pathogenesis and outcome of several disease states, including chronic hepatitis C (CHC). The kinetics of Regulated upon Activation Normal T cell Expressed and Secreted (RANTES) (CCL5) and IP-10 (CXCL10) during direct-acting antivirals (DAA) treatment was retrospectively analyzed in 18 liver transplant recipients (LT-R) compared with 20 patients with CHC and 49 healthy controls (HC). CK levels were determined at baseline, week 4, end of treatment, 24 weeks post-treatment (sustained virological response [SVR]), and later-on during follow-up (FU), 12 and 24 months post-DAA. At baseline, median RANTES levels were higher in HC than in both LT-R (p > 0.01) and CHC (p > 0.01), whereas IP-10 levels were higher in LT-R and CHC than in HC (p > 0.05 and p = 0.01), respectively. Mean RANTES values increased during DAA therapy to peak at SVR and FU with significantly higher levels than at baseline in LT-R (p < 0.01) and in CHC, but only at FU (p < 0.003). A subsequent return to baseline or lower levels was observed at extended FU. On the contrary, IP-10 values showed a significant decrease from baseline to SVR and FU in both LT-R (p < 0.03) and CHC (p < 0.01). RANTES profiles during the first 4 weeks of DAA treatment showed an increase or decrease from baseline according to baseline RANTES levels. CCR5 genotyping in LT-R showed the presence of 1 homozygous Δ32/Δ32 and 2 heterozygous WT/Δ32 haplotypes with a prevalence of 5.5% and 11.1%, respectively. In conclusion, although IP-10 showed the expected kinetics, the CC5 pathway appears extensively altered during CHC infection: monitoring these patients may be indicated as they may be at risk of other infections or immune-mediated disorders.

Gamma-Chain Receptor Cytokines & PD-1 Manipulation to Restore HCV-Specific CD8+ T Cell Response during Chronic Hepatitis C

Hepatitis C virus (HCV)-specific CD8⁺ T cell response is essential in natural HCV infection control, but it becomes exhausted during persistent infection. Nowadays, chronic HCV infection can be resolved by direct acting anti-viral treatment, but there are still some non-responders that could benefit from CD8⁺ T cell response restoration. To become fully reactive, T cell needs the complete release of T cell receptor (TCR) signalling but, during exhaustion this is blocked by the PD-1 effect on CD28 triggering. The T cell pool sensitive to PD-1 modulation is the progenitor subset but not the terminally differentiated effector population. Nevertheless, the blockade of PD-1/PD-L1 checkpoint cannot be always enough to restore this pool. This is due to the HCV ability to impair other co-stimulatory mechanisms and metabolic pathways and to induce a pro-apoptotic state besides the TCR signalling impairment. In this sense, gamma-chain receptor cytokines involved in memory generation and maintenance, such as low-level IL-2, IL-7, IL-15, and IL-21, might carry out a positive effect on metabolic reprogramming, apoptosis blockade and restoration of co-stimulatory signalling. This review sheds light on the role of combinatory immunotherapeutic strategies to restore a reactive anti-HCV T cell response based on the mixture of PD-1 blocking plus IL-2/IL-7/IL-15/IL-21 treatment.

Development of hepatic pathology in GBV-B-infected red-bellied tamarins (Saguinus labiatus)

GB virus B (GBV-B) is a new world monkey-associated flavivirus used to model acute hepatitis C virus (HCV) infection. Critical for evaluation of antiviral or vaccine approaches is an understanding of the effect of HCV on the liver at different stages of infection. In the absence of longitudinal human tissue samples at defined time points, we have characterized changes in tamarins. As early as 2 weeks post-infection histological changes were noticeable, and these were established in all animals by 6 weeks. Despite high levels of liver-associated viral RNA, there was reversal of hepatic damage on clearance of peripheral virus though fibrosis was demonstrated in four tamarins. Notably, viral RNA burden in the liver dropped to near undetectable or background levels in all animals which underwent a second viral challenge, highlighting the efficacy of the immune response in removing foci of replication in the liver. These data add to the knowledge of GBV-B infection in New World primates which can offer attractive systems for the testing of prophylactic and therapeutic treatments and the evaluation of their utility in preventing or reversing liver pathology.

Tumor necrosis family receptor superfamily member 9/tumor necrosis factor receptor-associated factor 1 pathway on hepatitis C viral persistence and natural history

Hepatitis C virus (HCV) infection is an excellent immunological model for understanding the mechanisms developed by non-cytopathic viruses and tumors to evade the adaptative immune response. The antigen-specific cytotoxic T cell response is essential for keeping HCV under control, but during persistent infection, these cells become exhausted or even deleted. The exhaustion process is progressive and depends on the infection duration and level of antigenemia. During high antigenic load and long duration of infection, T cells become extremely exhausted and ultimately disappear due to apoptosis. The development of exhaustion involves the impairment of positive co-stimulation induced by regulatory cytokines, such as transforming growth factor beta 1. This cytokine downregulates tumor necrosis factor receptor (TNFR)-associated factor 1 (TRAF1), the signal transducer of the T cell co-stimulatory molecule TNFR superfamily member 9 (known as 4-1BB). This impairment correlates with the low reactivity of T cells and an exhaustion phenotype. Treatment with interleukin-7 in vitro restores TRAF1 expression and rescues T cell effector function. The process of TRAF1 loss and its in vitro recovery is hierarchical, and more affected by severe disease progression. In conclusion, TRAF1 dynamics on T cells define a new pathogenic model that describes some aspects of the natural history of HCV, and sheds light on novel immunotherapy strategies for chronic viral infections and cancer.

Immune surveillance of the liver by T cells

The liver is the target of several infectious, inflammatory, and neoplastic diseases, which affect hundreds of millions of people worldwide and cause an estimated death toll of more than 2 million people each year. Dysregulation of T cell responses has been implicated in the pathogenesis of these diseases; hence, it is critically important to understand the function and fate of T cells in the liver. Here, we provide an overview of the current knowledge on liver immune surveillance by conventional and invariant T cells and explore the complex cross-talk between immune cell subsets that determines the balance between hepatic immunity and tolerance.

OMIP-068: High-Dimensional Characterization of Global and Antigen-Specific B Cells in Chronic Infection

This 24-color flow cytometry panel focuses on characterizing antigen-specific B cells and precise delineation of B-cell subsets in chronic infections and is applicable to other chronic diseases such as autoimmunity. The panel was optimized for human cryopreserved peripheral blood mononuclear cells (PBMCs). Markers were chosen to extensively distinguish B-cell lineages (CD19, CD20, CD10, CD38, CD24, IgM, IgD, CD27, CD21, CD43, CD5). Inclusion of antigen-specific probes was of high priority in order to assess hepatitis B virus (HBV) antigen-specific B cells for our purposes. These probes can be readily exchanged for other pathogen-specific probes or additional markers for the panel to be tailored to desired research questions beyond HBV. In addition, we included a comprehensive and unique set of functional markers such as chemokine receptors (CXCR3, CXCR5), co-stimulatory molecule (CD86), Fc receptor (CD32), regulatory molecules (BTLA, CD39), and inhibitory markers associated with chronic infections (PD-1, FcRL5, CD11c, CD22) to enable in-depth analysis of global and antigen-specific B cells during chronic infection. © 2020 International Society for Advancement of Cytometry.

Identification of the association between HBcAg-specific T cell and viral control in chronic HBV infection using a cultured ELISPOT assay

Hepatitis B virus (HBV)-specific T cells play a critical role in determining the outcome of HBV infection. However, T cell response induced by predominant Ag in chronic infection is hardly detectable owing to the lack of a suitable assay. We herein established an optimized method to enumerate HBV-specific T cells and assessed the association between HBV surface Ag (HBsAg) and HBV DNA. Sixty chronic HBV infection patients were enrolled. HBV-specific T cells were expanded by using overlapping peptide pools covering the entire sequence of HBV genotypes B and C. IFN-γ-producing HBV-specific T cells were detected by a cultured enzyme-linked immunospot (ELISPOT) assay, ex vivo ELISPOT assay, or flow cytometry staining. The association between HBV-specific T cells and serum levels of HBsAg and HBV DNA were analyzed. Cultured ELISPOT assay had a higher sensitivity than ex vivo ELISPOT in the detection of HBV-specific T cells. Moreover, consistent results were acquired by flow cytometry analysis and cultured ELISPOT assay, but the latter required only a limited number of cells for detection. Interestingly, HBV core peptide pool induced a robust HBV-specific T cell response in patients with lower levels of HBV DNA and HBsAg. Specifically, the frequency of HBV core Ag-specific IFN-γ⁺ spot-forming cells was inversely correlated with serum levels of HBV DNA and HBsAg. An optimized cultured ELISPOT assay reveals the association between HBV core Ag-induced T cell response and HBV control; this method may favor the investigation of HBV-specific T cell in chronic HBV infection.

Peripheral Expression of CXCL10 Gene in Chronic Hepatitis C Patients Treated with Sofosbuvir, Daclatasvir, and Ribavirin

Hepatitis C virus (HCV) causes persistent infection and invades host's innate and adaptive immune systems. During the eradication of this pathogen, the components of immune system may cause bystander damage to host, which might be even worse than the viral pathogenesis. Thus, the therapy should not only eliminate primary virus infection but also improve the inflammatory immune responses. The breakthrough of interferon free direct acting antiviral (DAA) drugs has provided the opportunity to unravel the association of HCV with immune response. This study aimed to examine the expression level of C-X-C motif chemokine ligand 10 (CXCL10) in the Peripheral blood mononuclear cells (PBMCs) of HCV infected patients treated with DAAs + Ribavirin. In this study we analyzed the expression levels of CXCL10 mRNA in the 90 chronic HCV patients using quantitative PCR (qPCR) prior, after, and during therapy with sofosbuvir/ribavirin (SOF+RBV) and sofosbuvir/daclatasvir/ribavirin (SOF+DCV+RBV), and further, the results were analyzed relative to treatment response. Significantly elevated CXCL10 mRNA was seen in naive patients having higher viral load (P = 0.005) and those suffering from hepatocellular carcinoma (P = 0.006). HCV patients had remarkable decline in CXCL10 level after 4, 12, and 24 weeks of therapy with DAAs. An approximate one-fold decrease was observed in patients who attained sustained virological response compared to untreated patients (P < 0.0001). Comparing the 2 regimens, the reduction in peripheral CXCL10 expression was more pronounced in patients undergoing SOF+DCV+RBV therapy. The current study implicitly shows the role of CXCL10 as an indicator of disruption of host-virus equilibrium and consequent pathogenesis of HCV during successful antiviral therapy. Furthermore, the drop in CXCL10 level after HCV viral clearance might reflect the DAA-induced alleviation in the extrahepatic manifestation of this infection.

Immune Cell Trafficking to the Liver

The human liver is an organ with a diverse array of immunologic functions. Its unique anatomic position that leads to it receiving all the mesenteric venous blood, combined with its unique micro anatomy, allows it to serve as a sentinel for the body's immune system. Hepatocytes, biliary epithelial cells, Kupffer cells, stellate cells, and liver sinusoidal endothelial cells express key molecules that recruit and activate innate and adaptive immunity. Additionally, a diverse array of lymphoid and myeloid immune cells resides within and traffics to the liver in specific circumstances. Derangement of these trafficking mechanisms underlies the pathophysiology of autoimmune liver diseases, nonalcoholic steatohepatitis, and liver transplantation. Here, we review these pathways and interactions along with potential targets that have been identified to be exploited for therapeutic purposes.

Beyond HIV infection: Neglected and varied impacts of CCR5 and CCR5Δ32 on viral diseases

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CCR5 regulates multiple cell types (e.g., T regulatory and Natural Killer cells) and immune responses.

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The effects of CCR5, CCR5Δ32 (variant associated with reduced CCR5 expression) and CCR5 antagonists vary between infections.

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CCR5 affects the pathogenesis of flaviviruses, especially in the brain.

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The genetic variant CCR5Δ32 increases the risk of symptomatic West Nile virus infection.

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The triad “CCR5, extracellular vesicles and infections” is an emerging topic.

The interactions between chemokine receptors and their ligands may affect susceptibility to infectious diseases as well as their clinical manifestations. These interactions mediate both the traffic of inflammatory cells and virus-associated immune responses. In the context of viral infections, the human C-C chemokine receptor type 5 (CCR5) receives great attention from the scientific community due to its role as an HIV-1 co-receptor. The genetic variant CCR5Δ32 (32 base-pair deletion in CCR5 gene) impairs CCR5 expression on the cell surface and is associated with protection against HIV infection in homozygous individuals. Also, the genetic variant CCR5Δ32 modifies the CCR5-mediated inflammatory responses in various conditions, such as inflammatory and infectious diseases. CCR5 antagonists mimic, at least in part, the natural effects of the CCR5Δ32 in humans, which explains the growing interest in the potential benefits of using CCR5 modulators for the treatment of different diseases. Nevertheless, beyond HIV infection, understanding the effects of the CCR5Δ32 variant in multiple viral infections is essential to shed light on the potential effects of the CCR5 modulators from a broader perspective. In this context, this review discusses the involvement of CCR5 and the effects of the CCR5Δ32 in human infections caused by the following pathogens: West Nile virus, Influenza virus, Human papillomavirus, Hepatitis B virus, Hepatitis C virus, Poliovirus, Dengue virus, Human cytomegalovirus, Crimean-Congo hemorrhagic fever virus, Enterovirus, Japanese encephalitis virus, and Hantavirus. Subsequently, this review addresses the impacts of CCR5 gene editing and CCR5 modulation on health and viral diseases. Also, this article connects recent findings regarding extracellular vesicles (e.g., exosomes), viruses, and CCR5. Neglected and emerging topics in “CCR5 research” are briefly described, with focus on Rocio virus, Zika virus, Epstein-Barr virus, and Rhinovirus. Finally, the potential influence of CCR5 on the immune responses to coronaviruses is discussed.

Chemokine-Regulated Recruitment of Antigen-Specific T-Cell Subpopulations to the Liver in Acute and Chronic Hepatitis C Infection

BACKGROUND

In hepatitis C virus (HCV) infection, virus-specific CD8+ T cells are recruited to the liver for antiviral activity. Multiple chemokine ligands are induced by the infection, notably interferon-inducible chemokine, CXCL10. In HCV, intrahepatic T cells express chemokine receptors (CCRs), including CXCR3, CXCR6, CCR1, and CCR5, but CCR expression on antigen-specific effector and memory T cells has not been investigated.

METHODS

Paired blood and liver samples were collected from subjects with chronic HCV for flow cytometric analysis of CCR expression on CD8+ T cells. Expression of these CCRs was then examined on HCV-specific CD8+ T-cell subpopulations in the blood from subjects with acute or chronic HCV.

RESULTS

Relative to peripheral blood, the liver was enriched with CD8+ T cells expressing CCR2, CCR5, CXCR3, and CXCR6 either singly or in combinations. CXCR3 was preferentially expressed on HCV-specific CD8+ T cells in both acute and chronic phases of infection in blood. Both CXCR3 and CCR2 were overexpressed on HCV-specific CD8+CCR7+CD45RO+ (central memory) cells, whereas effector memory (CD8+CCR7-CD45RO+) cells expressed more CXCR6.

CONCLUSIONS

CXCR3-mediated signals support the accumulation of HCV-specific CD8+ memory T cells in the infected liver, and emphasize the importance of the CXCL10/CXCR3 trafficking pathway during acute and chronic HCV infection.

Key features and homing properties of NK cells in the liver are shaped by activated iNKT cells

The contribution of natural killer (NK) cells to the clearance of hepatic viral infections is well recognized. The recently discovered heterogeneity of NK cell populations renders them interesting targets for immune interventions. Invariant natural killer T (iNKT) cells represent a key interaction partner for hepatic NK cells. The present study addressed whether characteristics of NK cells in the liver can be shaped by targeting iNKT cells. For this, the CD1d-binding pegylated glycolipid αGalCerMPEG was assessed for its ability to modulate the features of NK cells permanently or transiently residing in the liver. In vivo administration resulted in enhanced functionality of educated and highly differentiated CD27⁺ Mac-1⁺ NK cells accompanied by an increased proliferation. Improved liver homing was supported by serum-derived and cellular factors. Reduced viral loads in a mCMV infection model confirmed the beneficial effect of NK cells located in the liver upon stimulation with αGalCerMPEG. Thus, targeting iNKT cell-mediated NK cell activation in the liver represents a promising approach for the establishment of liver-directed immune interventions.

Immunomodulation of CXCL10 Secretion by Hepatitis C Virus: Could CXCL10 Be a Prognostic Marker of Chronic Hepatitis C?

Chemokine (C-X-C motif) ligand (CXCL)10 and other CXCR3 chemokines are involved in the pathogenesis of acute and "chronic hepatitis C virus (HCV) infection" (CHC). Here, we review the scientific literature about HCV and CXCL10. The combination of circulating CXCL10 and single nucleotide polymorphisms (SNPs) in IL-28B can identify patients with acute HCV infection most likely to undergo spontaneous HCV clearance and those in need of early antiviral therapy. In CHC, the HCV and intrahepatic interferon- (IFN-) γ drive a raised CXCL10 expression by sinusoidal endothelium and hepatocytes, thereby inducing the recruitment of CXCR3-expressing T cells into the liver; thus, CXCL10 plays an important role in the development of necroinflammation and fibrosis. Increased CXCL10 was significantly associated with the presence of active vasculitis in HCV-associated cryoglobulinemia, or with autoimmune thyroiditis in CHC. Pretreatment CXCL10 levels are predictive of early virological response and sustained virological response (SVR) to IFN-α and ribavirin and may be useful in the evaluation of candidates for therapy. The occurrence of SNPs adjacent to IL-28B (rs12979860, rs12980275, and rs8099917), and CXCL10 below 150 pg/mL, independently predicted the first phase viral decline and rapid virological response, which in turn independently predicted SVR. Directly acting antiviral agents-mediated clearance of HCV is associated with the loss of intrahepatic immune activation by IFN-α, associated by decreased levels of CXCL10. In conclusion, CXCL10 is an important marker of HCV clearance and successful therapy in CHC patients. Whether CXCL10 is a novel therapeutic target in CHC will be evaluated.

Circulating CXCR3+ Tfh cells positively correlate with neutralizing antibody responses in HCV-infected patients

Circulating T follicular helper (cTfh) cells have been identified as counterparts of germinal center Tfh (GC Tfh) cells in humans and can support T-dependent B cell maturation and antibody production in vitro. However, the role of cTfh cells in neutralizing antibody (nAb) responses in HCV infection remains unclear. Here, we characterized the phenotype and function of cTfh cells and demonstrated the associations of cTfh cells and their subsets with nAb responses in HCV infection. A total of 38 HCV-infected individuals and 28 healthy controls were enrolled from a pool of injection drug users. The frequency and function of blood Tfh cells were analyzed by flow cytometry. The titers and breadths of serum nAbs were measured using HCV pseudo-particle neutralization assays. Herein, we report several key observations. First, HCV infection skewed cTfh toward CXCR3⁺ cTfh cell differentiation. Second, the frequency of CXCR3⁺ cTfh cells positively correlated with HCV nAb titers and breadths. Third, CXCR3⁺ cTfh cells showed higher expression of Tfh-associated molecules (PD-1, ICOS, IL-21, Bcl-6) compared with CXCR3⁻ cTfh cells from individuals with HCV infection. Coculture of cTfh cells and autologous memory B cells in vitro indicated that CXCR3⁺ cTfh cells show a superior ability to support HCV E2-specific B cell expansion compared with CXCR3⁻ cTfh cells from individuals with HCV infection. HCV infection skews cTfh cells toward CXCR3-biased Tfh cell differentiation, which positively correlates with the magnitude and breadth of the HCV nAb response. It is our hope that these findings will provide insights for the rational design of a nAb-based HCV vaccine.

Hepatitis C: From inflammatory pathogenesis to anti-inflammatory/hepatoprotective therapy

Hepatitis C virus (HCV) infection commonly causes progressive liver diseases that deteriorate from chronic inflammation to fibrosis, cirrhosis and even to hepatocellular carcinoma. A long-term, persistent and uncontrolled inflammatory response is a hallmark of these diseases and further leads to hepatic injury and more severe disease progression. The levels of inflammatory cytokines and chemokines change with the states of infection and treatment, and therefore, they may serve as candidate biomarkers for disease progression and therapeutic effects. The mechanisms of HCV-induced inflammation involve classic pathogen pattern recognition, inflammasome activation, intrahepatic inflammatory cascade response, and oxidative and endoplasmic reticulum stress. Direct-acting antivirals (DAAs) are the first-choice therapy for effectively eliminating HCV, but DAAs alone are not sufficient to block the uncontrolled inflammation and severe liver injury in HCV-infected individuals. Some patients who achieve a sustained virologic response after DAA therapy are still at a long-term risk for progression to liver cirrhosis and hepatocellular carcinoma. Therefore, coupling with anti-inflammatory/hepatoprotective agents with anti-HCV effects is a promising therapeutic regimen for these patients during or after treatment with DAAs. In this review, we discuss the relationship between inflammatory mediators and HCV infection, summarize the mechanisms of HCV-induced inflammation, and describe the potential roles of anti-inflammatory/hepatoprotective drugs with anti-HCV activity in the treatment of advanced HCV infection.

Quantitative analysis of serum chemokines associated with treatment failure of direct-acting antivirals in chronic hepatitis C

Although serum chemokine levels have been reported to influence the outcome of interferon-based treatment in patients with chronic hepatitis C, their effect on the hepatitis C virus (HCV) response to direct-acting antiviral agents (DAAs), which can achieve high rates of a sustained virological response (SVR), is largely unknown. To clarify this relationship, 9 chemokines (eotaxin, GRO-α, IL-8, IP-10, MCP-1, MIP-1α, MIP-1β, RANTES, and SDF-1α) were quantified before, during, and after DAA treatment using serum samples obtained from 57 patients with chronic hepatitis C. All baseline median chemokine levels were significantly higher in patients with chronic hepatitis C than in healthy subjects (P < 0.05). In particular, lower MIP-1β (≤71.5 pg/mL) and higher RANTES (>671.5 pg/mL) levels were significantly associated with patients who failed to clear HCV RNA (P = 0.0039 and 0.013, respectively). Prediction of a clinical response based on a combination of these chemokines demonstrated high sensitivity (82%), specificity (85%), negative predictive value (95%), and area under the curve (0.833). The non-SVR rate (56.3%; 9 of 16) was significantly higher in patients with low MIP-1β and high RANTES compared with other combinations. Moreover, baseline MIP-1β and RANTES were both additive and independent for predicting a non-SVR. Apart from an increase in eotaxin, all chemokines became decreased in patients with a SVR. In conclusion, a combination of serum MIP-1β and RANTES levels may be predictive of a treatment response to DAAs in Japanese patients with chronic hepatitis C.

CCL4 is the only predictor for non-responder in GT-1 CHC patients with favorable IL28B genotype when treated with PegIFN/RBV

BACKGROUND

Chemokines/cytokines play important roles in the pathogenesis of chronic hepatitis C (CHC). However, their clinical characteristics and implications in treatment responses to pegylated interferon plus ribavirin treatment (PegIFN/RBV) have not been fully illustrated yet. In this study, we intended to investigate the possible predictability of serum chemokines/cytokines on the treatment response in Taiwanese of CHC, genotype-1 (GT-1).

METHODS

60 Patients with GT-1 CHC infection who had been treated with PegIFN/RBV were enrolled, including 27 (45%) with sustained virological response (SVR), 11 (18%) with relapse after 48 weeks of treatment and 22 (37%) non-response (NR). Clinical parameters, seven chemokines/cytokines, CCL3, CCL4, CXCL9, CXCL10, CXCL11, IL-10 and IFN-γ, and genotypes of rs12979860, the single nucleotide polymorphisms (SNPs) of interleukin-28B (IL28B) were analyzed for their relationship to treatment response.

RESULTS

Baseline serum levels of CXCL10, CXCL11, CCL3 and CCL4 were significantly higher in NR group while comparing with non-NR group. (CXCL10: p = 0.001; CXCL11: p < 0.001; CCL3: p = 0.006; CCL4: p = 0.005). However, only rs12979860 CC genotype was the independent factors for NR in GT-1 CHC infection (OR, 8.985; p = 0.008). In addition, baseline serum level of CCL4 was found to be the only independent factor for NR in GT-1 CHC patients with favorable IL28B genotype (OR, 1.134; p = 0.039).

CONCLUSIONS

IL28B genotype is the predictor for NR in GT-1 CHC patients treated with PegIFN/RBV, while baseline serum level of CCL4 is the only predictor for NR in GT-1 CHC patients with favorable IL28B genotype.

The effect of HIV infection and HCV viremia on inflammatory mediators and hepatic injury-The Women's Interagency HIV Study

Hepatitis C virus infection induces inflammation and while it is believed that HIV co-infection enhances this response, HIV control may reduce inflammation and liver fibrosis in resolved or viremic HCV infection. Measurement of systemic biomarkers in co-infection could help define the mechanism of inflammation on fibrosis and determine if HIV control reduces liver pathology. A nested case-control study was performed to explore the relationship of systemic biomarkers of inflammation with liver fibrosis in HCV viremic and/or seropositive women with and without HIV infection. Serum cytokines, chemokines, growth factors and cell adhesion molecules were measured in HIV uninfected (HIV-, n = 18), ART-treated HIV-controlled (ARTc, n = 20), uncontrolled on anti-retroviral therapy (ARTuc, n = 21) and elite HIV controllers (Elite, n = 20). All were HCV seroreactive and had either resolved (HCV RNA-; <50IU/mL) or had chronic HCV infection (HCV RNA+). In HCV and HIV groups, aspartate aminotransferase to platelet ratio (APRI) was measured and compared to serum cytokines, chemokines, growth factors and cell adhesion molecules. APRI correlated with sVCAM, sICAM, IL-10, and IP-10 levels and inversely correlated with EGF, IL-17, TGF-α and MMP-9 levels. Collectively, all HCV RNA+ subjects had higher sVCAM, sICAM and IP-10 compared to HCV RNA-. In the ART-treated HCV RNA+ groups, TNF-α, GRO, IP-10, MCP-1 and MDC were higher than HIV-, Elite or both. In ARTuc, FGF-2, MPO, soluble E-selectin, MMP-9, IL-17, GM-CSF and TGF-α are lower than HIV-, Elite or both. Differential expression of soluble markers may reveal mechanisms of pathogenesis or possibly reduction of fibrosis in HCV/HIV co-infection.

Pretreatment serum levels of interferon-gamma-inducible protein-10 are associated with virologic response to telaprevir-based therapy

AIM

Telaprevir (TVR) remarkably improves the efficacy of interferon treatment for chronic hepatitis C. Interleukin-28B (IL28B) genotype and interferon-gamma-inducible protein-10 (IP-10) level predict virologic response to peg-interferon (Peg-IFN)/ribavirin (RBV) therapy. We aimed to investigate the usefulness of pretreatment serum IP-10 levels and IL28B genotyping in predicting sustained virologic response (SVR) to TVR-based triple therapy.

METHODS

In this multi-center study, patients infected with hepatitis C virus genotype 1 with high viral load (⩾5.0logIU/mL) were treated with TVR for 12weeks and Peg-IFN/RBV for 24weeks in Japan. IL28B genotype, serum IP-10 levels, other clinical parameters, and drug dosages were assessed before treatment.

RESULTS

We included 121 patients who were treated with TVR for at least 8weeks and Peg-IFN/RBV for 24weeks. The median IP-10 levels were significantly lower in rapid virologic response (RVR) or SVR in the IL28B non-TT genotype group, with no significant difference in the TT genotype group. RVR rates were significantly lower in the group with higher serum IP-10 levels (>450pg/mL). In the non-TT IL28B genotype group, RVR and SVR rates were significantly lower in the group with higher IP-10 levels. SVR rates in the group with lower IP-10 levels (<450pg/mL) increased to 82% for those showing RVR, but reduced to 27% in the group with higher IP-10 levels for those not showing RVR.

CONCLUSIONS

Determination of serum IP-10 levels before treatment could be useful for predicting favorable virologic response to TVR-based triple therapy, especially in patients with IL28B non-TT genotype.

Intrahepatic regulation of antiviral T cell responses at initial stages of viral infection

It is generally accepted that the appropriate boost of early immune response will control viral replications and limit the immune-mediated pathology in viral hepatitis. However, poor immunity results in viral persistence, chronic inflammation and finally liver cirrhosis and carcinoma. As a peripheral non-lymphoid organ of immune surveillance, the liver continually encounters hundreds of molecules from the blood, including nutrients, toxins and pathogens. In this way, the liver maintains immune tolerance under healthy conditions, but responds quickly to the hepatotropic pathogens during the early stages of an infection. Although our knowledge of liver cell compositions and functions has been improved significantly in recent years, the intrahepatic immune regulation of antiviral T cells at the initial stage is complex and not well elucidated. Here, we summarize the role of liver cell subpopulations in regulating antiviral T cell response at the initial stages of viral infection. A better understanding of early hepatic immune regulation will pave the way for the development of novel therapies and vaccine design for human viral hepatitis.

Association of IL28B Genotypes and Baseline Serum Interferon-γ-Inducible- Protein-10 Levels with Treatment Response in Hepatitis C Virus Patients in China

BACKGROUND/AIMS

Several studies have demonstrated that serum interferon-γ-inducible-protein-10 (IP-10) levels at baseline and single nucleotide polymorphisms (SNPs) near the IL28B gene were associated with viral response and treatment outcomes. Our purpose was to assess the combination of pretreatment IP-10 levels with IL28B SNPs as predictors of treatment response to pegylated interferon α-2a plus ribavirin in patients infected with genotype 1 hepatitis C virus in China.

METHODS

Seventy-two patients with chronic hepatitis C without fibrosis/cirrhosis were enrolled in the study. The virologic parameters and baseline serum IP-10 levels were determined. IL-28B genotypes were determined by sequencing.

RESULTS

In this cohort, serum baseline IP-10 levels lower than 426.7 pg/mL could predict rapid virological response/ sustained virological response (SVR). Patients carrying favorable IL28B SNP genotypes had higher SVRs than did those carrying unfavorable variants (IL28B rs12979860, p=0.002; IL28B rs8099917, p=0.020). Combining both baseline IP- 10 and IL28B SNPs could improve the prediction of SVR in favorable allele carriers of IL28B, rs12979860 CC and rs8099917 TT. Serum baseline IP-10 levels and IL28B genotypes were independent predictors of SVR.

CONCLUSIONS

Our study shows that the combination of baseline serum IP-10 levels and the determination of IL28B SNPs increase the predictability of SVR rates in this cohort. (Gut Liver 2016;10446-455).

Systemic inflammation and liver damage in HIV/hepatitis C virus coinfection

OBJECTIVES

Chronic hepatitis C virus (HCV) and HIV viral infections are characterized by systemic inflammation. Yet the relative levels, drivers and correlates of inflammation in these settings are not well defined.

METHODS

Seventy-nine HIV-infected patients who had been receiving antiretroviral therapy (ART) for more than 2 years and who had suppressed plasma HIV levels (< 50 HIV-1 RNA copies/mL) were included in the study. Two patient groups, HCV-positive/HIV-positive and HCV-negative/HIV-positive, and a control group comprised of healthy volunteers (n = 20) were examined. Markers of systemic inflammation [interleukin (IL)-6, interferon gamma-induced protein (IP)-10, soluble tumour necrosis factor receptor-I (sTNF-RI) and sTNF-RII], monocyte/macrophage activation [soluble CD163 (sCD163), soluble CD14 and neopterin], intestinal epithelial barrier loss [intestinal fatty acid binding protein (I-FABP) and lipopolysaccharide (LPS)] and coagulation (d-dimers) were analysed. CD4 naïve T cells and CD4 recent thymic emigrants (RTEs) were enumerated.

RESULTS

Plasma levels of IP-10, neopterin and sCD163 were higher in HCV/HIV coinfection than in HIV monoinfection and were positively correlated with indices of hepatic damage [aspartate aminotransferase (AST), alanine aminotransferase (ALT) and the AST to platelet ratio index (APRI)]. Levels of I-FABP were comparably increased in HIV monoinfection and HIV/HCV coinfection but LPS concentrations were highest in HCV/HIV coinfection, suggesting impaired hepatic clearance of LPS. Plasma HCV levels were not related to any inflammatory indices except sCD163. In coinfected subjects, a previously recognized relationship of CD4 naïve T-cell and RTE counts to hepatocellular injury was defined more mechanistically by an inverse relationship to sCD163.

CONCLUSIONS

Hepatocellular injury in HCV/HIV coinfection is linked to elevated levels of certain inflammatory cytokines and an apparent failure to clear systemically translocated microbial products. A related decrease in CD4 naïve T cells and RTEs also merits further exploration.

Oral nucleos(t)ide analogues reduce recurrence and death in chronic hepatitis B-related hepatocellular carcinoma

BACKGROUND

In patients with chronic hepatitis B (CHB)-related hepatocellular carcinoma (HCC), high viral load was associated with tumour recurrence and deaths.

AIMS

To investigate the effect of nucleos(t)ide analogues (NA) on the clinical outcomes after different HCC treatments.

METHODS

A territory-wide cohort study was conducted using the database from Hospital Authority. We identified CHB patients with HCC by International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes in 2000-2012. HCC treatments, NA use and laboratory parameters were retrieved. The primary endpoint was HCC recurrence and death. A 3-month landmark analysis was used to evaluate the primary outcome in patients with or without NA treatment.

RESULTS

A total of 2198 CHB patients (1230 NA-untreated and 968 NA-treated) with HCC, receiving at least one type of HCC treatment were included in the analysis. At a median follow-up of 2.8 (IQR 1.4-4.9) years, tumour recurrence and death occurred in 451 (36.7%) and 578 (47.0%) untreated patients; and in 216 (22.3%) and 301 (31.1%) NA-treated patients respectively. NA therapy reduced the risk of overall HCC recurrence [adjusted sub-hazard ratio (SHR) 0.63, 95% confidence interval (CI) 0.49-0.80; P < 0.001]. The effect was most obvious in patients undergoing resection (SHR = 0.58, 95% CI = 0.37-0.91, P = 0.018). The possibility of NA therapy reducing the risk of death (HR = 0.82, 95% CI = 0.64-1.03, P = 0.092), is most obvious in resection subgroup (HR = 0.64, 95% CI = 0.41-0.99, P = 0.050) but insignificant in the other treatment groups.

CONCLUSION

Our findings show that nucleos(t)ide analogues treatment reduces the risk of HCC recurrence in patients with chronic hepatitis B treated by surgical resection.

Chemokine receptor CXCR3 in turbot (Scophthalmus maximus): cloning, characterization and its responses to lipopolysaccharide

Chemokine (C-X-C motif) receptor 3, a member of the G protein-coupled receptors superfamily, regulates the responses of many immune responses. In this experiment, we cloned and characterized the cDNA of CXCR3 in Scophthalmus maximus (turbot). A 5'-UTR of 216-bp, a 259-bp 3'-UTR with a poly (A) tail and a 1089-bp CDS encoding 362 amino acids form the cDNA of CXCR3, which is 1564-bp long. Phylogenetic analyses indicated that turbot CXCR3 shared a high similarity with other CXCR3s and shared more similarity with CXCR5 than the other subfamilies of chemokines. The CXCR3 protein in turbot showed the highest similarity with the CXCR3b from rainbow trout (44.5%), which indicated that this CXCR3 gene/protein may be a CXCR3b isoform. Quantitative real-time PCR analysis showed that CXCR3 transcripts were constitutively expressed in all the tissues of the non-injected turbot used in this study, with the highest expression occurring in blood. Several immune-related tissues of fish, such as the spleen, head kidney, liver and blood, tissues, which were abundant of lymphocyte, were investigated in this study. CXCR3 gene was expressed at the highest level in blood than the other tested tissues. The injection experiment suggested that the CXCR3 expression level after LPS injection was significantly up-regulated in all immune-related tissues in turbot. These results improve our understanding of the functions of CXCR3 in the turbot immune response.

High MIG (CXCL9) plasma levels favours response to peginterferon and ribavirin in HCV-infected patients regardless of DPP4 activity

BACKGROUND & AIMS

Sustained virological response (SVR) following peginterferon (pegIFN) and ribavirin (RBV) treatment in hepatitis C virus (HCV)-infected patients has been linked with the IL28B genotype and lower peripheral levels of the CXCR3-binding chemokine IP-10 (CXCL10). To further improve the understanding of these biomarkers we investigated plasma levels of the other CXCR3-binding chemokines and activity of the dipeptidyl peptidase IV (DPP4, CD26) protease, which cleaves IP-10, in relation to treatment response.

METHODS

African-American and Caucasian HCV genotype 1-infected patients (n = 401) were treated with pegIFN/RBV for 48 weeks (ViraHep-C cohort). Pretreatment plasma levels of MIG (CXCL9), I-TAC (CXCL11) and the type III interferon IL29 were investigated by Luminex and DPP4 activity by using a luciferase assay.

RESULTS

Patients achieving SVR had higher baseline MIG plasma levels and lower DPP4 activity than non-SVR patients. MIG was higher in Caucasians, IL28B CC (rs1297860) genotype carriers and patients with higher ALT levels. MIG correlated with IP-10 in SVR patients, but not in non-SVRs. A high DPP4 activity correlated with higher IP-10 levels, while DPP4 activity was not associated with MIG or I-TAC levels.

CONCLUSIONS

The associations of MIG with SVR status and IL28B genotype imply that higher MIG plasma levels could reflect a beneficial immunological state for response to pegIFN/RBV treatment. The correlation between MIG and IP-10 observed only in SVR patients may contribute to a better treatment response, whereas this MIG/IP-10 balance might be disrupted in non-SVR patients because of the increased DPP4 cleavage of IP-10 into a dysfunctional form.

Serum interferon-inducible protein 10 levels predict hepatitis B s antigen seroclearance in patients with chronic hepatitis B

BACKGROUND

Hepatitis B s antigen (HBsAg) seroclearance is regarded as the optimal virological end-point.

AIM

To investigate the dynamic changes in serum cytokine levels around the time of HBsAg seroclearance.

METHODS

This was a case-control study. Consecutive patients with chronic hepatitis B (CHB) who lost HBsAg were matched with those remained positive for HBsAg with same age, gender, HBeAg status and presence of cirrhosis in 1:2 ratio. Relevant serum cytokines [interleukin (IL)-2, IL-3, IL-4, IL-7, IL-9, IL-10, IL-12, IL-15, IL-21 interferon-γ, tumour necrosis factor-α (TNF-α), granulocyte macrophage colony-stimulating factor (GM-CSF) and interferon-inducible protein 10 (IP-10)] were assayed at the time (Year 0) and 3 years before (Year -3) HBsAg seroclearance.

RESULTS

Seventy-one and 142 CHB patients who did and did not achieve HBsAg seroclearance were included. Mean age was 48 ± 11 years; 76% were male, 20% had positive HBeAg, 99 (46%) patients received anti-viral therapy, and mean baseline HBV DNA was 3.78 ± 2.28 log IU/mL vs. 4.36 ± 2.13 log IU/mL respectively (P = 0.05). In those who achieved HBsAg seroclearance, serum IL-15 and GM-CSF levels decreased significantly from Year -3 to Year 0 (P = 0.017 and 0.05 respectively). When compared to controls, only serum IP-10 level was significantly lower at Year 0 than at Year -3 in patients with HBsAg seroclearance. Lower serum IP-10 level at Year 0 was the only factor associated with HBsAg seroclearance. There was no correlation between serum IP-10 and HBsAg levels around the time of HBsAg seroclearance.

CONCLUSION

Lower serum IP-10 level at Year 0 was the only factor associated with HBsAg seroclearance.

Plasma levels of growth-related oncogene (CXCL1-3) associated with fibrosis and platelet counts in HCV-infected patients

BACKGROUND

Fibrosis progression in hepatitis C virus (HCV)-infected patients varies greatly between individuals. Chemokines recruit immune cells to the infected liver and may thus play a role in the fibrosis process.

AIM

To investigate plasma levels of a diverse chemokine panel in relation to liver fibrosis.

METHODS

African-American and Caucasian HCV genotype 1 infected patients were treated with peginterferon (pegIFN) and ribavirin (RBV) for 48 weeks (VIRAHEP-C cohort). Plasma levels of 13 cytokines were studied at baseline (n = 386). Subsequently, GROα levels were assessed in a sub cohort (n = 99) at baseline, and at 4 and 12 weeks after start of pegIFN/RBV treatment.

RESULTS

Increased severity of fibrosis (Ishak fibrosis score 0-2 vs. 3-6) was associated with increased plasma IP-10 (CXCL10) and IL-8 (CXCL8) levels, and decreased plasma levels of the chemokine growth-related oncogene (GRO, CXCL1-3). Plasma GRO levels were also positively correlated with platelet counts, and were higher in African-American as compared to Caucasian patients. In response to pegIFN/RBV treatment, GROα levels increased in Caucasian but not African-American patients from week 4 onwards.

CONCLUSIONS

The association with severity of fibrosis and platelet count positions plasma GRO as a potential biomarker for liver fibrosis in HCV-infected patients. The secretion of GRO by platelets may explain the correlation between GRO plasma level and platelet count. The ethnic difference in GRO levels both pre-treatment and in response to pegIFN/RBV might be driven by a genetic polymorphism in GROα associated with higher plasma levels and more common in the African-American population.

Dynamic Changes of Post-Translationally Modified Forms of CXCL10 and Soluble DPP4 in HCV Subjects Receiving Interferon-Free Therapy

Serum levels of the interferon (IFN)-stimulated chemokine CXCL10 are increased during chronic HCV infection and associate with outcome of IFN-based therapy. Elevated levels of NH2-terminal truncated CXCL10 (3-77aa), produced by DPP4 cleavage, negatively associate with spontaneous clearance of acute HCV infection and sustained virological response (SVR) with IFN-based therapy for chronic infection. The association of different CXCL10 forms and DPP4 with outcome during IFN-free HCV therapy has not been examined. Using novel Simoa assays, plasma was analyzed from HCV genotype-1 (GT1) subjects who relapsed (n = 11) or achieved SVR (n = 10) after sofosbuvir and ribavirin (SOF/RBV) treatment, and from SOF/RBV relapsers who achieved SVR with a subsequent SOF/ledipasvir regimen (n = 9). While the NH2-truncated form of CXCL10 was elevated in HCV infection relative to healthy controls, pre-treatment plasma concentrations of CXCL10 forms failed to stratify subjects based on treatment outcome to IFN-free regimens. However, a trend (statistically non-significant) towards elevated higher levels of total and long CXCL10 was observed pre-treatment in subjects who relapsed. All forms of CXCL10 decreased rapidly following treatment initiation and were again elevated in subjects who experienced HCV relapse, indicating that CXCL10 production may be associated with active viral replication. While soluble DPP4 (sDPP4) and NH₂-truncated CXCL10 concentrations were highly correlated, on-treatment sDPP4 levels and activity declined more slowly than CXCL10, suggesting differential regulation.

The 3 major types of innate and adaptive cell-mediated effector immunity

The immune system has tailored its effector functions to optimally respond to distinct species of microbes. Based on emerging knowledge on the different effector T-cell and innate lymphoid cell (ILC) lineages, it is clear that the innate and adaptive immune systems converge into 3 major kinds of cell-mediated effector immunity, which we propose to categorize as type 1, type 2, and type 3. Type 1 immunity consists of T-bet(+) IFN-γ-producing group 1 ILCs (ILC1 and natural killer cells), CD8(+) cytotoxic T cells (TC1), and CD4(+) TH1 cells, which protect against intracellular microbes through activation of mononuclear phagocytes. Type 2 immunity consists of GATA-3(+) ILC2s, TC2 cells, and TH2 cells producing IL-4, IL-5, and IL-13, which induce mast cell, basophil, and eosinophil activation, as well as IgE antibody production, thus protecting against helminthes and venoms. Type 3 immunity is mediated by retinoic acid-related orphan receptor γt(+) ILC3s, TC17 cells, and TH17 cells producing IL-17, IL-22, or both, which activate mononuclear phagocytes but also recruit neutrophils and induce epithelial antimicrobial responses, thus protecting against extracellular bacteria and fungi. On the other hand, type 1 and 3 immunity mediate autoimmune diseases, whereas type 2 responses can cause allergic diseases.

Pretreatment serum macrophage inflammatory protein (MIP)-1 levels predict sustained virological responses to re-treatment in patients with chronic hepatitis C virus infection

BACKGROUND

There are few predictors of the virological response in patients who are re-treated with antiviral therapies. In this study, we evaluated the levels of chemokines that bind to C-C chemokine receptor type 5 (CCR5) and their impact on combination therapy in both treatment-naïve and treatment-experienced patients chronically infected with hepatitis C virus (HCV).

METHODS

Longitudinal analysis of CCR5 chemokines was performed using the multiplex Bio-Rad 27-plex assay in 56 treatment-naïve and 24 treatment-experienced patients with chronic HCV infection during combination therapy with peginterferon alfa and ribavirin. A group of healthy donors was included as the control (n=11).

RESULTS

The pretreatment level of macrophage inflammatory protein 1 (MIP-1) was determined to be an independent predictor, with an ideal predictive threshold for sustained virological response of 95.23 pg/ml. A rapid decline in HCV RNA was observed in patients with a pretreatment MIP-1 level of <95.23 pg/ml, while a slow reduction was measured in patients with levels of ≥95.23 pg/ml (p=0.014). Of note, the dynamics of MIP-1 further indicated that a lower level at baseline and at treatment week 12 was significantly associated with a favorable outcome of antiviral therapy (p=0.014), especially in treatment-experienced patients (p=0.04), while a higher level of MIP-1beta correlated with the elevation of transaminases.

CONCLUSIONS

Serum MIP-1 is an independent and effective predictor of early and sustained virological response in chronically HCV-infected patients undergoing re-treatment.

Clinical significance of the CCR5delta32 allele in hepatitis C

Background

The CCR5 receptor, expressed on Th1 cells, may influence clinical outcomes of HCV infection. We explored a possible link between a CCR5 32-base deletion (CCR5delta32), resulting in the expression of a non-functioning receptor, and clinical outcomes of HCV infection.

Methods

CCR5 and HCV-related phenotypes were analysed in 1,290 chronically infected patients and 160 patients with spontaneous clearance.

Results

Carriage of the CCR5delta32 allele was observed in 11% of spontaneous clearers compared to 17% of chronically infected patients (OR = 0.59, 95% CI interval 0.35–0.99, P = 0.047). Carriage of this allele also tended to be observed more frequently among patients with liver inflammation (19%) compared to those without inflammation (15%, OR = 1.38, 95% CI interval 0.99–1.95, P = 0.06). The CCR5delta32 was not associated with sustained virological response (P = 0.6), fibrosis stage (P = 0.8), or fibrosis progression rate (P = 0.4).

Conclusions

The CCR5delta32 allele appears to be associated with a decreased rate of spontaneous HCV eradication, but not with hepatitis progression or response to antiviral therapy.

Roles for chemokines in liver disease

Sustained hepatic inflammation is an important factor in progression of chronic liver diseases, including hepatitis C or non-alcoholic steatohepatitis. Liver inflammation is regulated by chemokines, which regulate the migration and activities of hepatocytes, Kupffer cells, hepatic stellate cells, endothelial cells, and circulating immune cells. However, the effects of the different chemokines and their receptors vary during pathogenesis of different liver diseases. During development of chronic viral hepatitis, CCL5 and CXCL10 regulate the cytopathic versus antiviral immune responses of T cells and natural killer cells. During development of nonalcoholic steatohepatitis, CCL2 and its receptor are up-regulated in the liver, where they promote macrophage accumulation, inflammation, fibrosis, and steatosis, as well as in adipose tissue. CCL2 signaling thereby links hepatic and systemic inflammation related to metabolic disorders and insulin resistance. Several chemokine signaling pathways also promote hepatic fibrosis. Recent studies have shown that other chemokines and immune cells have anti-inflammatory and antifibrotic activities. Chemokines and their receptors can also contribute to the pathogenesis of hepatocellular carcinoma, promoting proliferation of cancer cells, the inflammatory microenvironment of the tumor, evasion of the immune response, and angiogenesis. We review the roles of different chemokines in the pathogenesis of liver diseases and their potential use as biomarkers or therapeutic targets.

CD127 expression, exhaustion status and antigen specific proliferation predict sustained virologic response to IFN in HCV/HIV co-infected individuals

Hepatitis C virus (HCV) infection is a major cause of morbidity and mortality in the HIV co-infected population. Interferon-alpha (IFN-α) remains a major component of anti-HCV therapy despite its deleterious effects on the immune system. Furthermore, IFN-α was recently shown to diminish the size of the latent HIV reservoir. The objectives of this study were to monitor the impact of IFN-α on T cell phenotype and proliferation of HIV and HCV-specific T cells during IFN therapy, and to identify immune markers that can predict the response to IFN in HICV/HIV co-infected patients. We performed longitudinal analyses of T cell numbers, phenotype and function in co-infected patients undergoing IFN-α therapy with different outcomes including IFN-α non-responders (NR) (n = 9) and patients who achieved sustained virologic response (SVR) (n = 19). We examined the expression of activation (CD38, HLA-DR), functional (CD127) and exhaustion markers (PD1, Tim-3, CD160 and CD244) on total CD4 and CD8 T cells before, during and after therapy. In addition, we examined the HIV- and HCV-specific proliferative responses against HIV-p24 and HCV-NS3 proteins. Frequencies of CD127⁺ CD4 T cells were higher in SVR than in NR patients at baseline. An increase in CD127 expression on CD8 T cells was observed after IFN-α therapy in all patients. In addition, CD8 T cells from NR patients expressed a higher exhaustion status at baseline. Finally, SVR patients exhibited higher proliferative response against both HIV and HCV antigens at baseline. Altogether, SVR correlated with higher expression of CD127, lower T cell exhaustion status and better HIV and HCV proliferative responses at baseline. Such factors might be used as non-invasive methods to predict the success of IFN–based therapies in co-infected individuals.

Effects of the Chemokine Receptor 5 (CCR5)-Delta32 Mutation on Hepatitis C Virus-Specific Immune Responses and Liver Tissue Pathology in HCV Infected Patients

BACKGROUND

The specific antiviral T cells provide CC chemokine receptor 5 (CCR5) for the immune response during the hepatitis C virus (HCV) infection. Heterogenous and/or homozygous 32 base pair deletion in CCR5 gene (CCR5Δ32 bpdel) leads to reduced protein expression.

OBJECTIVES

In the current case control study, we aimed to compare the histopathological findings of liver to the CCR5Δ32 bpdel mutation profiles, expression and some other clinical findings in patients with chronic HCV infection.

MATERIALS AND METHODS

Multiple Strip Assay reverse hybridisation and Real Time PCR techniques were used to determine the germline CCR5 mutations and immunohistochemical technique was used to evaluate the gene expression in targer tissue biopsies.

RESULTS

Target CCR5 WT/WT, WT/Δ32, and Δ32/Δ32 genotypes were observed in 91.4%, 8.6% and 0.0% for HCV positive patients and 98.3%, 1.7% and 0.0% for control group respectively. The histologic activity index (HAI) was significantly lower (4.0 ± 1.0) in the mutated group than the non-mutated group (5.7 ± 1.0). Decreased fibrosis levels were detected in HCV positive mutated group.

CONCLUSIONS

Results showed that CCR5 polymorphism was more frequent in HCV positive patients than in healthy population in Turkish population. Current results also showed that mutated CCR5 signalling pathway due to CCR5-Delta32 may potentially result in subtle reduction of HCV specifity to the drug responses due to the positive impact on liver inflammation, fibrosis levels and liver destruction in HCV infection.

Adaptive immune response during hepatitis C virus infection

Hepatitis C virus (HCV) infection affects about 170 million people worldwide and it is a major cause of liver cirrhosis and hepatocellular carcinoma. HCV is a hepatotropic non-cytopathic virus able to persist in a great percentage of infected hosts due to its ability to escape from the immune control. Liver damage and disease progression during HCV infection are driven by both viral and host factors. Specifically, adaptive immune response carries out an essential task in controlling non-cytopathic viruses because of its ability to recognize infected cells and to destroy them by cytopathic mechanisms and to eliminate the virus by non-cytolytic machinery. HCV is able to impair this response by several means such as developing escape mutations in neutralizing antibodies and in T cell receptor viral epitope recognition sites and inducing HCV-specific cytotoxic T cell anergy and deletion. To impair HCV-specific T cell reactivity, HCV affects effector T cell regulation by modulating T helper and Treg response and by impairing the balance between positive and negative co-stimulatory molecules and between pro- and anti-apoptotic proteins. In this review, the role of adaptive immune response in controlling HCV infection and the HCV mechanisms to evade this response are reviewed.

Positioning of leukocyte subsets in the portal and lobular compartments of hepatitis C virus-infected liver correlates with local chemokine expression

BACKGROUND AND AIM

Chronic hepatitis C virus infection is characterized by infiltration of a mixed population of leukocytes into portal tracts and infiltration almost exclusively by CD8+ T cells into lobules of the liver. This pattern of leukocyte recruitment is likely to be orchestrated in a cell-specific fashion by local chemokine expression.

METHODS

Portal or lobular tissues were isolated by laser capture microdissection from 17 liver biopsy specimens to examine regional gene expression of a panel of chemokine ligands and receptors. The biopsies were also stained immunohistochemically to enumerate regional cell numbers.

RESULTS

Expression of multiple chemokine ligands and receptors was evident, although few correlated with leukocyte numbers. In the lobule, expression of CXCL10 correlated with T-cell subsets (CD3+, P = 0.0002; CD4+, P = 0.0053; and CD8+, P = 0.0061), as did CCL5 (CD3+, P = 0.0005; CD8+, P = 0.0199) and CCL3 (CD3+, P = 0.0016; CD8+, P = 0.008). In the portal tracts, expression of CXCL10 and CCL5 was correlated with CD8+ T-cell numbers (P = 0.0040 and P = 0.0114, respectively), whereas CXCL13 was strongly correlated with CD20+ B-cell numbers (P < 0.0001). CXCR3 expression correlated with CD3+ and CD4+ T cells (P < 0.0001 and P = 0.0208, respectively), CCR5 with CD8+ T cells (P < 0.0001), and CXCR5 with CD20+ B-cell infiltration (P = 0.0022).

CONCLUSION

CXCR3, CCR5, and CXCR5 and their ligands form key elements of the "zip code" responsible for regional localization of specific lymphocyte subsets in the HCV-infected liver.

The role of chemokines in hepatitis C virus-mediated liver disease

The hepatitis C virus (HCV) is a global health problem affecting more than 170 million people. A chronic HCV infection is associated with liver fibrosis, liver cirrhosis and hepatocellular carcinoma. To enable viral persistence, HCV has developed mechanisms to modulate both innate and adaptive immunity. The recruitment of antiviral immune cells in the liver is mainly dependent on the release of specific chemokines. Thus, the modulation of their expression could represent an efficient viral escape mechanism to hamper specific immune cell migration to the liver during the acute phase of the infection. HCV-mediated changes in hepatic immune cell chemotaxis during the chronic phase of the infection are significantly affecting antiviral immunity and tissue damage and thus influence survival of both the host and the virus. This review summarizes our current understanding of the HCV-mediated modulation of chemokine expression and of its impact on the development of liver disease. A profound knowledge of the strategies used by HCV to interfere with the host's immune response and the pro-fibrotic and pro-carcinogenic activities of HCV is essential to be able to design effective immunotherapies against HCV and HCV-mediated liver diseases.

Direct, interferon-independent activation of the CXCL10 promoter by NF-κB and interferon regulatory factor 3 during hepatitis C virus infection

Hepatitis C virus (HCV) infection of hepatocytes leads to transcriptional induction of the chemokine CXCL10, which is considered an interferon (IFN)-stimulated gene. However, we have recently shown that IFNs are not required for CXCL10 induction in hepatocytes during acute HCV infection. Since the CXCL10 promoter contains binding sites for several proinflammatory transcription factors, we investigated the contribution of these factors to CXCL10 transcriptional induction during HCV infection in vitro. Wild-type and mutant CXCL10 promoter-luciferase reporter constructs were used to identify critical sites of transcriptional regulation. The proximal IFN-stimulated response element (ISRE) and NF-κB binding sites positively regulated CXCL10 transcription during HCV infection as well as following exposure to poly(I·C) (a Toll-like receptor 3 [TLR3] stimulus) and 5' poly(U) HCV RNA (a retinoic acid-inducible gene I [RIG-I] stimulus) from two viral genotypes. Conversely, binding sites for AP-1 and CCAAT/enhancer-binding protein β (C/EBP-β) negatively regulated CXCL10 induction in response to TLR3 and RIG-I stimuli, while only C/EBP-β negatively regulated CXCL10 during HCV infection. We also demonstrated that interferon-regulatory factor 3 (IRF3) is transiently recruited to the proximal ISRE during HCV infection and localizes to the nucleus in HCV-infected primary human hepatocytes. Furthermore, IRF3 activated the CXCL10 promoter independently of type I or type III IFN signaling. The data indicate that sensing of HCV infection by RIG-I and TLR3 leads to direct recruitment of NF-κB and IRF3 to the CXCL10 promoter. Our study expands upon current knowledge regarding the mechanisms of CXCL10 induction in hepatocytes and lays the foundation for additional mechanistic studies that further elucidate the combinatorial and synergistic aspects of immune signaling pathways.

Independent, parallel pathways to CXCL10 induction in HCV-infected hepatocytes

BACKGROUND & AIMS

The pro-inflammatory chemokine CXCL10 is induced by HCV infection in vitro and in vivo, and is associated with outcome of IFN (interferon)-based therapy. We studied how hepatocyte sensing of early HCV infection via TLR3 (Toll-like receptor 3) and RIG-I (retinoic acid inducible gene I) led to expression of CXCL10.

METHODS

CXCL10, type I IFN, and type III IFN mRNAs and proteins were measured in PHH (primary human hepatocytes) and hepatocyte lines harboring functional or non-functional TLR3 and RIG-I pathways following HCV infection or exposure to receptor-specific stimuli.

RESULTS

HuH7 human hepatoma cells expressing both TLR3 and RIG-I produced maximal CXCL10 during early HCV infection. Neutralization of type I and type III IFNs had no impact on virus-induced CXCL10 expression in TLR3+/RIG-I+ HuH7 cells, but reduced CXCL10 expression in PHH. PHH cultures were positive for monocyte, macrophage, and dendritic cell mRNAs. Immunodepletion of non-parenchymal cells (NPCs) eliminated marker expression in PHH cultures, which then showed no IFN requirement for CXCL10 induction during HCV infection. Immunofluorescence studies also revealed a positive correlation between intracellular HCV Core and CXCL10 protein expression (r(2) = 0.88, p ≤ 0.001).

CONCLUSIONS

While CXCL10 induction in hepatocytes during the initial phase of HCV infection is independent of hepatocyte-derived type I and type III IFNs, NPC-derived IFNs contribute to CXCL10 induction during HCV infection in PHH cultures.

The role of chemokines in acute and chronic hepatitis C infection

Hepatitis C imposes a significant burden on global healthcare. Chronic infection is associated with progressive inflammation of the liver which typically manifests in cirrhosis, organ failure and cancer. By virtue of elaborate evasion strategies, hepatitis C virus (HCV) succeeds as a persistent human virus. It has an extraordinary capacity to subvert the immune response enabling it to establish chronic infections and associated liver disease. Chemokines are low molecular weight chemotactic peptides that mediate the recruitment of inflammatory cells into tissues and back into the lymphatics and peripheral blood. Thus, they are central to the temporal and spatial distribution of effector and regulatory immune cells. The interactions between chemokines and their cognate receptors help shape the immune response and therefore, have a major influence on the outcome of infection. However, chemokines represent a target for modulation by viruses including the HCV. HCV is known to modulate chemokine expression in vitro and may therefore enable its survival by subverting the immune response in vivo through altered leukocyte chemotaxis resulting in impaired viral clearance and the establishment of chronic low-grade inflammation. In this review, the roles of chemokines in acute and chronic HCV infection are described with a particular emphasis placed on chemokine modulation as a means of immune subversion. We provide an in depth discussion of the part played by chemokines in mediating hepatic fibrosis while addressing the potential applications for these chemoattractants in prognostic medicine.

CXCR3 axis in patients with primary biliary cirrhosis: a possible novel mechanism of the effect of ursodeoxycholic acid

The CXC chemokines, monokine induced by interferon (IFN)-gamma (MIG) (CXCL9), IFN-gamma-induced protein 10 (IP-10) (CXCL10) and IFN-inducible T cell alpha chemoattractant (I-TAC) (CXCL11), are known to attract CXCR3- (CXCR3A and CXCR3B) T lymphocytes. We investigated MIG, IP-10 and I-TAC mRNAs expression by semi-quantitative multiplex reverse transcription-polymerase chain reaction (RT-PCR) in liver biopsies obtained from patients with a first diagnosis of primary biliary cirrhosis [(PBC) = 20] compared to patients with normal liver biopsy [normal controls (NCs) = 20]. Chemokine production was assessed by enzyme-linked immunosorbent assay (ELISA) in serum. Measurements were repeated 6 months after ursodeoxycholic acid (UDCA) treatment in PBC patients. CXCR3A and CXCR3B mRNAs expression was examined in immunomagnetically sorted CD3(+) peripheral blood lymphocytes (PBL) pre- and post-treatment by RT-PCR. Flow cytometry was used to evaluate the expression of CXCR3(+) PBLs of NCs and PBC patients. A marked mRNA expression of MIG and IP-10 was found in PBC patients. I-TAC mRNA was not detected. In serum of PBC patients there was a significant increase of MIG and IP-10 compared to NCs. Interestingly, there was a significant reduction of these proteins in patients' serum after UDCA treatment. I-TAC was not statistically different between groups. CXCR3A mRNA expression was found in PBLs from PBC patients as well as in NCs. CXCR3B mRNA was expressed in four of 20 (19%) NCs and 20 of 20 PBC patients. Flow cytometry revealed a significantly lower CXCR3 expression in NCs (13·5%) than in PBC (37·2%), which was reduced (28·1%, P < 0·01) after UDCA administration. These data suggest a possible role for CXCR3-binding chemokines and their receptor in the aetiopathogenetic recruitment of lymphocytes in PBC and a new mechanism of action for UDCA.

Persistent hepatitis C virus (HCV) infection impairs HCV-specific cytotoxic T cell reactivity through Mcl-1/Bim imbalance due to CD127 down-regulation

In persistent hepatitis C virus (HCV) infection, HCV-specific cytotoxic T lymphocyte (CTL) reactivity is impaired and this affects HCV control. Interleukin-7 receptor (CD127) expression on these cells could regulate CTL reactivity through Mcl-1/Bim balance modulation. Bim is a pro-apoptotic molecule blocked by the action of Mcl-1. Mcl-1/Bim expression and T cell reactivity on HCV-specific CTLs were compared according to CD127 phenotype. Peripheral blood lymphocytes (PBL) from HLA-A2(+) HCV(+) patients were obtained. HCV-specific CTLs were visualized by staining PBL with anti-CD8 and HLA-A2/peptide pentameric complexes (pentamer). Mcl-1/Bim/CD127 phenotype of HCV-specific CTLs was tested by staining detectable CD8(+)/pentamer(+) cells with anti-Mcl-1/Bim/CD127 antibodies. HCV-specific CTL proliferation ability after specific in vitro challenge was tested in the presence and absence of pancaspase inhibitor z-VAD-fmk. All stained cells were analysed by flow cytometry. CD127(low)-expressing HCV-specific CTLs associated with high HCV viraemia, while CD127(high) correlated with undetectable viral loads (P < 0.001). Directly ex vivo, pentamer(+) cell frequency was similar according to CD127 expression level. Nevertheless, CD127(low) pentamer(+) cell proliferation after specific in vitro challenge was impaired (P < 0.05), although this was corrected by z-VAD-fmk treatment (P < 0.05). Mcl-1 expression was low directly ex vivo (P < 0.01), and Bim was up-regulated after antigen encounter (P < 0.05) of CD127(low) pentamer(+) cells. The ex vivo difference between Mcl-1 and Bim expression on pentamer(+) cells correlated positively with CD127 expression level (P < 0.001) and with pentamer(+) cell reactivity (P < 0.05). In summary, a low ex vivo Mcl-1 expression and Bim up-regulation after antigen encounter are involved in CD127(low) HCV-specific CTL hyporeactivity during chronic infection, but it can be overcome by apoptosis blockade.

Hepatitis C virus-related hepatocellular carcinoma: An insight into molecular mechanisms and therapeutic strategies

Hepatitis C virus (HCV) infects more than 170 million people worldwide, and thereby becomes a series global health challenge. Chronic infection with HCV is considered one of the major causes of end-stage liver disease including cirrhosis and hepatocellular carcinoma. Although the multiple functions of the HCV proteins and their impacts on the modulation of the intracellular signaling transduction processes, the drive of carcinogenesis during the infection with HCV, is thought to result from the interactions of viral proteins with host cell proteins. Thus, the induction of mutator phenotype, in liver, by the expression of HCV proteins provides a key mechanism for the development of HCV-associated hepatocellular carcinoma (HCC). HCC is considered one of the most common malignancies worldwide with increasing incidence during the past decades. In many countries, the trend of HCC is attributed to several liver diseases including HCV infection. However, the development of HCC is very complicated and results mainly from the imbalance between tumor suppressor genes and oncogenes, as well as from the alteration of cellular factors leading to a genomic instability. Besides the poor prognosis of HCC patients, this type of tumor is quite resistance to the available therapies. Thus, understanding the molecular mechanisms, which are implicated in the development of HCC during the course of HCV infection, may help to design a general therapeutic protocol for the treatment and/or the prevention of this malignancy. This review summarizes the current knowledge of the molecular mechanisms, which are involved in the development of HCV-associated HCC and the possible therapeutic strategies.