Enhanced expression of interferon-regulated genes in the liver of patients with chronic hepatitis C virus infection: detection by suppression-subtractive hybridization

The immune response in chronic HBV infection

Hepatitis B virus (HBV) is an ancient virus that has evolved unique strategies to persist as a chronic infection in humans. Here, I summarize the innate and adaptive features of the HBV-host interaction, and I discuss how different profiles of antiviral immunity cannot be predicted only on the basis of virological and clinical parameters.

During HCV DAA Therapy Plasma Mip1B, IP10, and miRNA Profile Are Distinctly Associated with Subsequent Diagnosis of Hepatocellular Carcinoma: A Pilot Study

Background: Hepatitis C virus (HCV) therapy lowers risk of hepatocellular carcinoma (HCC). Little is known about factors driving/preceding HCC in treated persons. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) regulate host response and pathogenesis of disease. We investigated plasma levels of these RNAs and select serum markers before, during, and after HCV therapy, preceding HCC. Methods: Of 187 DAA treated HCV patients where therapy oriented longitudinal sampling was performed at a time without HCC diagnosis, 9 were subsequently diagnosed with HCC within 2 years of therapy. They were matched with 7 patients not diagnosed with HCC over the same time period. RNASeq was performed on plasma, and serum was assessed for biomarkers of inflammation by ELISA. Results: HCC diagnosis was 19 months (6-28) after therapy start in the HCC group. 73 and 63 miRs were differentially expressed at baseline (before DAA therapy) and 12 weeks after DAA therapy comparing HCC and non-HCC groups. Several lncRNA- showed differential expression as well. Several miRNA suppressors of cancer-related pathways, lncRNA- and mRNA-derived stabilized short RNAs were consistently absent in the plasma of patients who developed HCC. Serum IP10, and MCP-1 level was higher in the HCC group 12 weeks after therapy, and distinct miRNAs correlated with IP10 and MCP-1. Finally, in a focused analysis of 8 miRNAs best associated with HCC we observed expression of mi576 and mi-5189 correlation with expression of a select group of PBMC mRNA. Conclusions: These results are consistent with complex interplay between RNA-mediated host immune regulation and cancer suppression, strikingly skewed 12 weeks following therapy, prior to HCC diagnosis.

Interleukin-6-Production Is Responsible for Induction of Hepatic Synthesis of Several Chemokines as Acute-Phase Mediators in Two Animal Models: Possible Significance for Interpretation of Laboratory Changes in Severely Ill Patients

Simple Summary

The release of acute-phase proteins and cytokine storms are considered critical parameters for the progression of COVID-19 disease. The increase in the serum levels of cytokines such as IL6 and IL8 observed in patients primarily infected with the SARS-CoV-2 virus has been used to determine the severity of clinical conditions resulting from infection and for prognostic purposes. Animal models have been used to understand the mechanisms of the changes in homeostasis observed under pathological conditions. In the present study, we therefore report the changes in serum levels and hepatic gene expression of cytokines and chemokines in two different animal models of acute-phase responses. The acute-phase response is a transient emergency response aimed at preserving life and bringing about the changes necessary to reduce and repair tissue damage after the removal of damaging noxious agents. Our data suggest that the liver may be responsible for the increase in the serum levels of cytokines and chemokines as part of the body’s defense response to tissue damage. It is therefore doubtful that inhibiting this response at any stage after infection could improve the prognosis of patients. These results may help to interpret the laboratory changes observed in critically ill patients, as may be the case following SARS-CoV-2 infection.

Abstract

A mild to moderate increase in acute-phase proteins (APPs) and a decrease in serum albumin levels are detected in hospitalized COVID-19 patients. A similar trend is also observed for acute-phase cytokines (APC), mainly IL6, besides chemokines (e.g., CXCL8 and CCL2). However, the source of the chemokines in these patients at different stages of disease remains to be elucidated. We investigated hepatic gene expression of CXC- and CC-chemokines in a model of a localized extrahepatic aseptic abscess and in a model of septicemia produced by the intramuscular injection of turpentine oil (TO) into each hindlimb or lipopolysaccharide (LPS) intraperitoneally (i.p.) in rats and mice (wild-type (WT) and IL6-KO). Together with a striking increase in the serum IL6 level, strong serum CXCL2 and CXCL8 concentrations were detected. Correspondingly, rapid (2 h) upregulation of CXCL1, CXCL2, CXCL5, and CXCL8 was observed in rat liver after intramuscular TO injection. The induction of the gene expression of CXCL1 and CXCL8 was the fastest and strongest. The hepatic CXC-chemokines behaved like positive APPs that depend on IL6 production by activated macrophages recruited to extrahepatic damaged tissue. Chemokine upregulation was greatly reduced in IL6-KO mice. However, IL6 was dispensable in the LPS–APR model, as massive induction of hepatic chemokines studied was measured in IL6-KO mice.

Interferon-γ-Inducible Protein 10 (IP-10) Kinetics after Antiretroviral Treatment Initiation in Ethiopian Adults with HIV

Interferon-γ-inducible protein 10 (IP-10) has been suggested as a marker for targeted viral load (VL) monitoring during antiretroviral treatment (ART). We aimed to determine the kinetics of IP-10 during the initial year of ART, with particular regard to the impact of tuberculosis (TB) co-infection on IP-10 secretion. Longitudinal plasma IP-10 levels were quantified in 112 treatment-naive HIV-positive adults at Ethiopian health centers, through enzyme-linked immunosorbent assay (ELISA) using samples obtained before and during the initial 12 months of ART. All participants underwent bacteriological TB investigation before starting ART. In virological responders (VRs; defined as VL < 150 copies/ml with no subsequent VL ≥ 1,000 copies/ml), IP-10 kinetics were analyzed using linear regression models. Among 91/112 (81.3%) participants classified as VRs, 17 (18.7%) had concomitant TB. Median baseline IP-10 was 650 pg/ml (interquartile range [IQR], 428-1,002) in VRs. IP-10 decline was more rapid during the first month of ART (median 306 pg/ml/month) compared with later time intervals (median 7-48 pg/ml/month, P < 0.001 in each comparison). Although VRs with TB had higher IP-10 levels at baseline (median 1106 pg/ml [IQR, 627-1,704]), compared with individuals without TB (median 628 pg/ml [IQR, 391-885]; P = 0.003), the rate of IP-10 decline during ART was similar, regardless of TB-status. During the initial year of ART, IP-10 kinetics followed a biphasic pattern in VRs, with a more rapid decline in the first month of ART compared with later time intervals. Baseline IP-10 was higher in individuals with TB versus individuals without TB, but the kinetics during ART were similar. IMPORTANCE To reach the goal of elimination of HIV as public health threat, access to antiretroviral treatment (ART) has to be further scaled up. To ensure viral suppression in individuals receiving ART, novel and robust systems for treatment monitoring are required. Targeting viral load monitoring to identify individuals at increased likelihood of treatment failure, using screening tools, could be an effective use of limited resources for viral load testing. Interferon-γ-inducible protein 10 (IP-10), a host inflammation mediator, has shown potential for this purpose. Here, we have investigated IP-10 kinetics in Ethiopian adults with HIV during the initial year after ART initiation. IP-10 levels decreased in parallel with viral load during ART, and prevalent tuberculosis at ART initiation did not influence IP-10 kinetics. This study shows satisfactory performance for IP-10 as a surrogate marker for viral load in persons starting ART, with no influence of concomitant tuberculosis.

HCV infection in hemophilia A patients is associated with altered cytokines and chemokines profile and might modulate the levels of FVIII inhibitor

Prevalence of hepatitis C virus (HCV) is high in hemophilia A patients and the development of FVIII inhibitor is another challenge in the management of these individuals. The influence of HCV infection in the occurrence of inhibitors was investigated by the comparison of clinical and laboratory data from noninfected (NI, n = 96) and chronically HCV-infected (HCV, n = 58) hemophilia A patients. Concentrations of plasmatic cytokines (IL-2, IL-4, IL-6, IL-10, TNF, IFN-γ, and IL-17A) and chemokines (CCL2, CCL5, CXCL8, CXCL9, and CXCL10) were quantified from patients' samples. The results showed that older age, use of cryoprecipitate and fresh frozen plasma, and severe hemophilia were associated with HCV infection, whereas exclusive use of virus inactivated clotting factors was a protector factor to acquiring HCV infection. HCV infection was strongly associated with low levels of inhibitor (OR = 20.53, p < 0.001). Patients with a history of inhibitor (INB+) presented a mixed immune profile characterized by higher levels of pro-and anti-inflammatory cytokines than those without a history of inhibitor (INB-). The highest levels of CCL2 and CXCL8 were seen in HCV^INB- , whereas CXCL9 and CXCL10 in HCV^INB+ . Heatmap analysis of the set of cytokines and chemokines concentration distributed HCV patients into two distinct clusters, HCV^INB+ and HCV^INB- , both characterized by low concentrations of IL-4, while noninfected patients were grouped in a single block regardless of inhibitor development history (NI^INB-/INB+ ). This finding suggests that the strong association between HCV infection and low levels of factor VIII inhibitors might be due to the modulation of the cytokine and chemokine network established by the antiviral response.

Hepatic IFNL4 Gene Activation in Hepatocellular Carcinoma Patients with Regard to Etiology

Hepatocellular carcinoma (HCC) is a malignancy with a leading lethality. The etiology is quite diverse, ranging from viral infections to metabolic disorders or intoxications, and associates with specific somatic mutational patterns and specific host immunological phenotypes. Particularly, hepatitis C virus (HCV)-infected liver is featured by an activation of interferon (IFN)-stimulated genes (ISGs; IFN signature), which we suppose is driven by type III IFNL4. Taking advantage of the TCGA collection of HCC patients of various different etiologies, this study aimed at validating our previous findings on hepatic IFNL4 gene activation in HCV infection in an independent and larger cohort of patients with advanced liver disease. In a cohort of n = 377 cases, the entirety of the sequencing data was used to assess the IFNL genotypes, and the cases were stratified for etiology. The number of IFNL4 transcripts within nonmalignant and malignant tissues was found to be more abundant in patients with HCV or HCV/HBV infections when compared to other risk factors. Moreover, in patients with HCV infection as a risk factor, a close, positive relationship was found between ISG activation and the number of functional IFNL4 transcripts. Data on this independent TCGA sample support the concept of an IFNL4-dependent HCV-driven activation of hepatic ISGs. In addition to that, they add to the understanding of etiology-related host immunological phenotypes in HCC.

Genetic polymorphisms of chemokine (C-X-C motif) ligand 10 gene associated with hepatitis B virus infection in a Chinese Han population

BACKGROUND AND AIMS

Chemokine (C-X-C motif) ligand 10 (CXCL10) has been recently shown to be associated with inflammatory diseases. However, the association between the genetic variation of this gene and the susceptibility to hepatitis B virus (HBV) infection remains unclear, especially in children. This study aimed to investigate the relationship between CXCL10 polymorphisms and the risk of chronic HBV infection in a Chinese Han population.

METHODS

A two-stage case-control study of 1048 adults and 627 children was performed. A total of 5 tagging SNPs in CXCL10 were genotyped. Dual-Luciferase Reporter Assay was used to assess the effect of the rs4508917 polymorphism on transcriptional activity of CXCL10.

RESULTS

CXCL10 rs4508917 and rs4256246 polymorphisms were significantly associated with an increased risk of chronic HBV infection in Chinese Han adults (p = 0.036 and p = 0.033), of which rs4508917 AA genotype could increase the serum CXCL10 level (p = 0.014). In addition, the rs4508917 AA genotype was identified to facilitate HBV persistent infection (p = 0.017) and breakthrough infection (p = 0.013) in children. Subsequent functional analysis indicated that rs4508917 A allele could promote the transcriptional activity of CXCL10. Additionally, we observed that the rs4508917 A allele carriers (AA and AG genotypes) had a limited HBV viral load suppression in patients treated with nucleos(t)ide analogues (NAs).

CONCLUSION

The A allele of the CXCL10 rs4508917 may be a risk factor of the persistent HBV infection both in adults and children, which may influence the response to NAs treatment.

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.

Active HCV infection is associated with increased circulating levels of interferon-gamma (IFN-γ)-inducible protein-10 (IP-10), soluble CD163 and inflammatory monocytes regardless of liver fibrosis and HIV coinfection

BACKGROUND AND OBJECTIVE

Interferon-gamma (IFN-γ)-inducible protein-10 (IP-10), soluble (s) CD163 and sCD14 play an important role in the pathogenesis of HCV and HIV infection and are involved in inflammation and liver fibrosis. The aim of the present study was to evaluate at a single time point, plasma soluble biomarkers and inflammatory monocytes subsets in different groups of subjects: (i) HIV monoinfected patients on suppressive ART; (ii) HIV/HCV coinfected patients on ART, with undetectable HIV viremia (including either subjects who had active HCV replication or those who cleared HCV); (iii) HCV monoinfected individual with active viral replication.

METHODS

Hundred and twenty-nine plasma samples were analyzed including HCV and HIV monoinfected patients, HIV/HCV coinfected patients, with active HCV infection (AHI) or with HCV viral clearance (VHC) and healthy donors (HD). Levels of IP-10, sCD163 and sCD14 were measured by ELISA. Absolute cell counts of monocyte subpopulations were enumerated in whole blood by using flow cytometric analyses.

RESULTS

IP-10 and sCD163 plasma levels were higher in HCV monoinfected and in AHI coinfected pts compared to HIV monoinfected and HD, whereas sCD14 levels were higher only in HIV monoinfected patients. Considering the degree of fibrosis, sCD163 and sCD14 levels positively correlated with kPa values (as assessed by fibroscan) and FIB-4 in HCV monoinfected group. On the other hand, IP-10 did not correlate with the fibrosis stage and it was found increased also in patients with low fibrosis. Moreover, we found an increase of the inflammatory NCM subset, in non-cirrhotic HCV subjects, while no alterations were observed in HIV, AHI and VHC.

CONCLUSIONS

Our study suggests a scenario in which active HCV infection is associated with a strong pro-inflammatory state, even in the initial stage of liver fibrosis, regardless the presence of HIV coinfection, thus underlying the need of an early anti-HCV treatment.

Differential Serum Cytokine Profiles in Patients with Chronic Hepatitis B, C, and Hepatocellular Carcinoma

Cytokines play an important role in the pathogenesis of cirrhosis and hepatocellular carcinoma (HCC), most cases of which are related to either hepatitis B virus (HBV) or hepatitis C virus (HCV). Prior studies have examined differences in individual cytokine levels in patients with chronic liver disease, but comprehensive cytokine profiling data across different clinical characteristics are lacking. We examined serum cytokine profiles of 411 patients with HCC (n = 102: 32% HBV, 54% HCV, 14% non-viral) and without HCC (n = 309: 39% HBV, 39% HCV, 22% non-viral). Multiplex analysis (Luminex 200 IS) was used to measure serum levels of 51 common cytokines. Random forest machine learning was used to obtain receiver operator characteristic curves and to determine individual cytokine importance using Z scores of mean fluorescence intensity for individual cytokines. Among HCC and non-HCC patients, cytokine profiles differed between HBV and HCV patients (area under curve (AUC) 0.82 for HCC, 0.90 for non-HCC). Cytokine profiles did not distinguish cirrhotic HBV patients with and without HCC (AUC 0.503) or HCV patients with and without HCC (AUC 0.63). In conclusion, patients with HBV or HCV infection, with or without HCC, have distinctly different cytokine profiles, suggesting potential differences in disease pathogenesis and/or disease characteristics.

Seasonality and autoimmune diseases: The contribution of the four seasons to the mosaic of autoimmunity

Autoimmune diseases (ADs) are a heterogeneous groups of diseases that occur as a results of loss of tolerance to self antigens. While the etiopathogeneis remain obscure, different environmental factors were suggested to have a role in the development of autoimmunity, including infections, low vitamin D levels, UV radiation, and melatonin. Interestingly, such factors possess seasonal variation patterns that could influence disease development, severity and progression. Vitamin D levels which reach a nadir during late winter and early spring is correlated with increased disease activity, clinical severity as well as relapse rates in several disease entities including multiple sclerosis (MS), non-cutaneous flares of systemic lupus erythematosus (SLE), psoriasis, and rheumatoid arthritis (RA). Additionally, immunomodulatory actions of melatonin secretion ameliorate the severity of several ADs including MS and SLE. Melatonin levels are lowest during spring, a finding that correlates with the highest exacerbation rates of MS. Further, melatonin is postulated to be involved in the etiopathogenesis of inflammatory bowel diseases (IBD) through it influence on adhesion molecule and therefore transcription factor expression. Moreover, infections can mount to ADs through pro-inflammatory cytokine release and human antigen mimicry. Seasonal patterns of infectious diseases are correlated with the onset and exacerbation of ADs. During the winter, increased incidence of Epstein-Barr virus (EBV) infectious are associated with MS and SLE flares/onset respectively. In addition, higher Rotavirus infections during the winter precedes type 1 diabetes mellitus onset (T1DM). Moreover, Escherichia coli (E. coli) infection prior to primary biliary cirrhosis (PBC) and T1DM disease onset subsequent to Coxachievirus infections are seen to occur during late summer, a finding that correlate with infectious agents' pattern of seasonality. In this review, the effects of seasonality on the onset, relapses and activity of various ADs were discussed. Consideration of seasonal variation patterns of ADs can possibly provide clues to diseases pathogenesis and lead to development of new approaches in treatment and preventative care.

Host factors associated with serologic inflammatory markers assessed using multiplex assays

Chronic systemic inflammation contributes to the development of adverse health conditions, yet the influence of fixed and modifiable risk factors on many serologic biomarkers of inflammation remains largely unknown. Serum concentrations of twenty-three biomarkers, including C-reactive protein (CRP), cytokines (CXCL11, CXCL8, CXCL10, CCL2, CCL13, CCL4, CCL17, CXCL13, IL-10, IL-12p70, IL-6, TNF-α, IL-2, IFN-γ, IL-1β, GM-CSF, BAFF), and soluble immune receptors (sCD14, sIL-2Rα, sCD27, sgp130, sTNF-R2) were measured longitudinally using multiplexed immunometric assays in 250 HIV-uninfected men followed in the Multicenter AIDS Cohort Study (1984-2009). Generalized gamma regression was used to determine the statistical significance of factors associated with each biomarker. After accounting for age, race, and education, and for analysis of multiple biomarkers, higher concentrations of specific individual biomarkers were significantly (P<0.002) associated with hypertension, obesity, hepatitis C infection, stimulant use, and diabetes and lower concentrations with hypercholesterolemia. These associations should be taken into account in epidemiological studies of these biomarkers, and may provide potential targets for disease prevention and treatment.

Suppression subtractive hybridization method for the identification of a new strain of murine hepatitis virus from xenografted SCID mice

During attempts to clone retroviral determinants associated with a mouse model of Langerhans cell histiocytosis (LCH), suppression subtractive hybridization (SSH) was used to identify unique viruses in the liver of severe combined immunodeficiency (SCID) mice transplanted with LCH tissues. A partial genomic sequence of a murine coronavirus was identified, and the whole genome (31428 bp) of the coronavirus was subsequently sequenced using PCR cloning techniques. Nucleotide sequence comparisons revealed that the genome sequence of the new virus was 91-93% identical to those of known murine hepatitis viruses (MHVs). The predicted open reading frame from the nucleotide sequence encoded all known proteins of MHVs. Analysis at the protein level showed that the virus was closely related to the highly virulent MHV-JHM strain. The virus strain was named MHV-MI. No type D retroviruses were found. Degenerate PCR targeting of type D retrovirus and 5'-RACE targeting of other types of retroviruses confirmed the absence of any retroviral association with the LCH xenografted SCID mice.

HCV Infection and Interferon-Based Treatment Induce p53 Gene Transcription in Chronic Hepatitis C Patients

It is suggested that the tumor suppressor p53 gene, classified as an interferon-stimulated gene, is implicated in the interferon (IFN)-mediated innate immunity against viruses. This study aimed to examine the transcriptional response of the p53 gene to hepatitis C virus (HCV) infection and IFN-based therapy in chronic hepatitis C (CHC) patients. The study included 65 CHC patients (HCV genotype 1), treated with pegylated IFN-α and ribavirin, and 51 healthy individuals. p53 gene expression was quantified by real-time polymerase chain reaction in peripheral blood mononuclear cells (PBMCs). Analyses were performed before and at weeks 4 and 12 of treatment. p53 gene expression was significantly upregulated in CHC patients compared with healthy controls and at week 4 of therapy. No significant differences in p53 mRNA expression between rapid virologic responders, complete early virologic responders, and nonresponders were observed. No significant correlation was found between p53 gene expression and viral load. The results obtained indicate that HCV infection and IFN-based treatment induces p53 gene transcription in PBMCs. The p53 gene may therefore play a role in HCV infection but is not directly involved in treatment-induced HCV elimination. Moreover, variations in p53 gene expression do not determine on-treatment response in patients with chronic HCV genotype 1 infection.

Cytokines and HCV-related autoimmune disorders

Cytokines are intercellular mediators involved in viral control and liver damage being induced by infection with hepatitis C virus (HCV). The complex cytokine network operating during initial infection allows a coordinated, effective development of both innate and adaptive immune responses. However, HCV interferes with cytokines at various levels and escapes immune response by inducing a T-helper (Th)2/T cytotoxic 2 cytokine profile. Inability to control infection leads to the recruitment of inflammatory infiltrates into the liver parenchyma by interferon (IFN)-γ-inducible CXC chemokine ligand (CXCL)9, -10, and -11 chemokines, which results in sustained liver damage and eventually in liver cirrhosis. The most important systemic HCV-related extrahepatic diseases-mixed cryoglobulinemia, lymphoproliferative disorders, thyroid autoimmune disorders, and type 2 diabetes-are associated with a complex dysregulation of the cytokine/chemokine network, involving proinflammatory and Th1 chemokines. The therapeutical administration of cytokines such as IFN-α may result in viral clearance during persistent infection and revert this process. Theoretically agents that selectively neutralize CXCL10 could increase patient responsiveness to traditional IFN-based HCV therapy. Several studies have reported IL-28B polymorphisms and circulating CXCL10 may be a prognostic markers for HCV treatment efficacy in HCV genotype 1 infection.

Immunological aspects of antiviral therapy of chronic hepatitis B virus and hepatitis C virus infections

Hepatitis B virus (HBV) and hepatitis C virus (HCV) cause a large proportion of acute and chronic liver disease worldwide. Over the past decades many immunological studies defined host immune responses that mediate spontaneous clearance of acute HBV and HCV infection. However, host immune responses are also relevant in the context of treatment-induced clearance of chronic HBV and HCV infection. First, the pretreatment level of interferon-stimulated genes as well as genetic determinants of innate immune responses, such as single nucleotide polymorphisms near the IFNL3 gene, are strong predictors of the response to interferon-alpha (IFN-α)-based therapy. Second, IFN-α, which has been a mainstay of HBV and HCV therapy over decades, and ribavirin, which has also been included in interferon-free direct antiviral therapy for HCV, modulate host immune responses. Third, both IFN-α-based and IFN-α-free treatment regimens of HBV and HCV infection alter the short-term and long-term adaptive immune response against these viruses. Finally, treatment studies have not just improved the clinical outcomes, but also provided opportunities to study virus-host interaction. This review summarizes our current knowledge on how a patient's immune response affects the treatment outcome of HBV and HCV infection and how innate and adaptive immune responses themselves are altered by the different treatment regimens.

Activation of Type I and Type III Interferons in Chronic Hepatitis C

Infection with hepatitis C virus (HCV) results in chronic and progressive liver disease. Persistency rates add up to 85%. Despite recognition of the virus by the human host in peripheral blood and in the liver, immune response appears to be ineffective in clearing infection. The ability to spontaneously eradicate the virus as well as the outcome of infection upon therapy with human recombinant interferon-α (IFN-α) was found to correlate most closely with genetic variations within the region encoding the IFN-λ genes, as revealed by genome-wide association studies on main ethnic populations in 2009. This review summarizes the induction of type I and type III IFN genes and their effectors, the IFN-stimulated genes. It focusses on the in vivo situation in chronic HCV infection in man both in the peripheral blood compartment and in the liver. It also addresses the impact of genetic polymorphisms in the region of type III IFN genes on their activation. Finally, it discusses how antiviral drugs (i.e. IFN-α, ribavirin and the direct-acting antivirals) may complementarily control the activation of endogenous IFNs and succeed in combatting infections.

Hepatitis C virus: a silent killer relevant to dentistry

Around 25 years ago, hepatitis C virus (HCV) was identified, and following intense research and tremendous advancements, the infection is now potentially curable and even complete viral eradication is possible. It is also evident that HCV can be involved in some oral disorders, but more research is clearly warranted on oral health of HCV-infected patients. Given the global estimates on HCV epidemic and its likely huge economic impact, primary prevention and secondary prevention are worldwide priorities. However, investments are still insufficient to achieve these goals.

Autoimmune and neoplastic thyroid diseases associated with hepatitis C chronic infection

Frequently, patients with hepatitis C virus (HCV) chronic infection have high levels of serum anti-thyroperoxidase and/or anti-thyroglobulin autoantibodies, ultrasonographic signs of chronic autoimmune thyroiditis, and subclinical hypothyroidism, in female gender versus healthy controls, or hepatitis B virus infected patients. In patients with "HCV-associated mixed cryoglobulinemia" (MC + HCV), a higher prevalence of thyroid autoimmune disorders was shown not only compared to controls, but also versus HCV patients without cryoglobulinemia. Patients with MC + HCV or HCV chronic infection show a higher prevalence of papillary thyroid cancer than controls, in particular in patients with autoimmune thyroiditis. Patients with HCV chronic infection, or with MC + HCV, in presence of autoimmune thyroiditis, show higher serum levels of T-helper (Th)1 (C-X-C motif) ligand 10 (CXCL10) chemokine, but normal levels of Th2 (C-C motif) ligand 2 chemokine, than patients without thyroiditis. HCV thyroid infection could act by upregulating CXCL10 gene expression and secretion in thyrocytes recruiting Th1 lymphocytes that secrete interferon-γ and tumor necrosis factor-α. These cytokines might induce a further CXCL10 secretion by thyrocytes, thus perpetuating the immune cascade, which may lead to the appearance of autoimmune thyroid disorders in genetically predisposed subjects. A careful monitoring of thyroid function, particularly where nodules occur, is recommended in HCV patients.

Immunological alterations in hepatitis C virus infection

A higher prevalence of immunological processes has recently been reported in patients with hepatitis C virus (HCV) infection, focusing the attention of physicians and researchers on the close association between HCV and immune disorders. HCV lymphotropism represents the most important step in the pathogenesis of virus-related immunological diseases and experimental, virologic, and clinical evidence has demonstrated a trigger role for HCV both in systemic autoimmune diseases, such as rheumatoid arthritis, Sjögren syndrome, hemolytic anemia and severe thrombocytopenia, and in organ-specific autoimmune diseases, such as autoimmune hepatitis, thyroid disorders and diabetes. This review will outline the principal aspects of such HCV-induced immunological alterations, focusing on the prevalence of these less characterized HCV extrahepatic manifestations.

Interferon-λ4 (IFNL4) transcript expression in human liver tissue samples

Eradication of hepatitis C virus (HCV) infection, both spontaneous and treatment-induced, is marked by the wildtype allele C of a single nucleotide polymorphism upstream of the IL28B gene, rs12979860. This favorable allele was recently described to be in linkage disequilibrium with the wildtype allele TT of a dinucleotide polymorphism, ss469415590, located within a new protein-coding gene. While the TT allele introduces a frame-shift and disrupts the open reading frame, only the variant allele, ΔG, creates a novel type III interferon (IFN) protein, IFN-λ₄/IFNL4. Absence of IFNL4 is thus supposed to favor resolution of HCV infection. As to date IFNL4 mRNA transcription has only been investigated in polyI:C-stimulated primary human hepatocytes and not yet in HCV infection in vivo, this study analyzed IFNL4 mRNA expression in human liver biopsy specimens. Samples were obtained from patients with a broad panel of disorders including no liver disease, liver diseases of non-viral etiology, chronic hepatitis B and chronic hepatitis C. Hepatic IFNL4 transcripts were detectable exclusively in a subgroup of chronic hepatitis C patients (24/45). Their amounts were positively related to liver HCV RNA copy numbers (p = 0.0023, r = 0.56) suggesting that the hepatic viral load influences IFNL4 transcription irrespective of IFNL4 governing genotype. Both, the IFNL4 creating allele ΔG (p<0.0001) and actual IFNL4 transcription (p = 0.0015) were found to be correlated to the activation of IFN stimulatory genes (ISGs). By contrast, IFNL4 ss469415590 genotypes were not found to be related to IFN-λ_2/3/IL28 or IFN-λ₁/IL29 gene expression. In conclusion, this study is the first report on intrahepatic transcript levels of the recently discovered IFNL4 gene. Data indicate that HCV infection in particular might activate IFNL4 transcription in the liver. It provides a possible explanation as to why hepatitis C patients show ISG stimulation in their livers in the apparent absence of an induction of other IFN subtypes.

Chemokine (C-X-C motif) ligand (CXCL)10 in autoimmune diseases

(C-X-C motif) ligand (CXCL)10 (CXCL10) belongs to the ELR(-) CXC subfamily chemokine. CXCL10 exerts its function through binding to chemokine (C-X-C motif) receptor 3 (CXCR3), a seven trans-membrane receptor coupled to G proteins. CXCL10 and its receptor, CXCR3, appear to contribute to the pathogenesis of many autoimmune diseases, organ specific (such as type 1 diabetes, autoimmune thyroiditis, Graves' disease and ophthalmopathy), or systemic (such as rheumatoid arthritis, psoriatic arthritis, systemic lupus erythematosus, mixed cryoglobulinemia, Sjögren syndrome, or systemic sclerosis). The secretion of CXCL10 by cluster of differentiation (CD)4+, CD8+, natural killer (NK) and NK-T cells is dependent on interferon (IFN)-γ, which is itself mediated by the interleukin-12 cytokine family. Under the influence of IFN-γ, CXCL10 is secreted by several cell types including endothelial cells, fibroblasts, keratinocytes, thyrocytes, preadipocytes, etc. Determination of high level of CXCL10 in peripheral fluids is therefore a marker of host immune response, especially T helper (Th)1 orientated T-cells. In tissues, recruited Th1 lymphocytes may be responsible for enhanced IFN-γ and tumor necrosis factor-α production, which in turn stimulates CXCL10 secretion from a variety of cells, therefore creating an amplification feedback loop, and perpetuating the autoimmune process. Further studies are needed to investigate interactions between chemokines and cytokines in the pathogenesis of autoimmune diseases and to evaluate whether CXCL10 is a novel therapeutic target in various autoimmune diseases.

Hepatic interferon-gamma-induced protein-10 expression is more strongly associated with liver fibrosis than interleukin-28B single nucleotide polymorphisms in hepatocellular carcinoma resected patients with chronic hepatitis C

AIM

Single nucleotide polymorphisms (SNP) around IL-28B and interferon (IFN)-stimulated gene (ISG) expression are predictors of response to standard therapy involving IFN for chronic hepatitis C virus (HCV) infection. We analyzed the association between these predictors to improve the prediction of the response to IFN therapy after liver resection for hepatocellular carcinoma (HCC).

METHODS

Data were collected from 74 patients with HCV-induced HCC. The IL-28B genotype and hepatic ISG mRNA levels were analyzed to clarify their association, focusing on the progression of liver fibrosis.

RESULTS

Fifty patients were identified as having major alleles (rs8099917 TT) and the remaining 24 patients had minor alleles (rs8099917 TG or GG). Hepatic ISG15 expression was lower in the IL-28B major group than that in the IL-28B minor group (P < 0.005). IP-10 expression was similar between the IL-28B major and minor groups (P = 0.44). IP-10 expression was elevated with advancing stages of liver fibrosis in HCV infected patients (P = 0.005). In patients with mild or no fibrosis, the IL-28B major group had lower IP-10 expression than the IL-28B minor group (P = 0.02). However, in patients with advanced fibrosis, IP-10 expression was not different between the IL-28B major and minor groups (P = 0.66).

CONCLUSION

Hepatic ISG15 expression is associated with IL-28B polymorphisms, while IP-10 is strongly affected by liver fibrosis.

Autoimmune thyroid disorders in hepatitis C virus infection: Effect of interferon therapy

The hepatitis C virus infection represents an important public health problem and is associated with various hepatic and extrahepatic manifestations. Symptoms outside of the liver can occur in multiple organ systems, including hematologic, renal, dermatologic, endocrine, and rheumatologic systems. Among these different organ systems, special attention has focused on the endocrine system because it affects almost every organ in the body. Among the endocrine disorders, thyroid problems are the most common and the thyroid is one of the principal target organs for extrahepatic manifestations in HCV infected patients. In addition, research data suggest that interferon treatment may be associated with immune-mediated thyroid lesions. However, case reports suggest that the response of thyroid extrahepatic manifestations to interferon in patients with chronic HCV is greatly different. The objective of this study was to summarize currently available data on thyroid conditions associated with chronic HCV infection. Moreover, we investigate the incidence of the development of immune mediated thyroid disorders during interferon therapy in these patients.

Thyroid disturbance related to chronic hepatitis C infection: role of CXCL10

Association between autoimmune thyroid diseases (AITD) and hepatitis C is controversial, but may occur or worsen during alpha-interferon treatment. The mechanism responsible for autoimmune diseases in infected patients has not been fully elucidated. This study aims to evaluate the frequency of AITD in chronic hepatitis C and the association of chemokine (CXC motif) ligand 10 (CXCL10) and AITD. One hundred and three patients with chronic hepatitis C and 96 controls were prospectively selected to clinical, hormonal, thyroid autoimmunity and ultrasound exams, besides thyroxine-binding globulin (TBG) and CXCL10 measurements and hepatic biopsies. The frequency of AITD among infected subjects was similar to controls. TT3 and TT4 distributions were right shifted, as was TBG, which correlated to both of them. Thyroid heterogeneity and hypoechogenicity were associated with AITD. Increased vascularization was more prevalent in chronic hepatitis C.CXCL10 was higher in infected patients (p=0.007) but was not related to thyroid dysfunction. Increase in CXCL10 levels were consistent with hepatic necroinflammatory activity (p=0.011). In summary, no association was found between chronic hepatitis C and AITD. Infected subjects had higher TT3 and TT4 which were correlated to TBG. Increased CXCL10 was not associated to thyroid dysfunction in HCV-infected population.

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.

dsRNA-dependent protein kinase PKR and its role in stress, signaling and HCV infection

The double-stranded RNA-dependent protein kinase PKR plays multiple roles in cells, in response to different stress situations. As a member of the interferon (IFN)‑Stimulated Genes, PKR was initially recognized as an actor in the antiviral action of IFN, due to its ability to control translation, through phosphorylation, of the alpha subunit of eukaryotic initiation factor 2 (eIF2α). As such, PKR participates in the generation of stress granules, or autophagy and a number of viruses have designed strategies to inhibit its action. However, PKR deficient mice resist most viral infections, indicating that PKR may play other roles in the cell other than just acting as an antiviral agent. Indeed, PKR regulates several signaling pathways, either as an adapter protein and/or using its kinase activity. Here we review the role of PKR as an eIF2α kinase, its participation in the regulation of the NF-κB, p38MAPK and insulin pathways, and we focus on its role during infection with the hepatitis C virus (HCV). PKR binds the HCV IRES RNA, cooperates with some functions of the HCV core protein and may represent a target for NS5A or E2. Novel data points out for a role of PKR as a pro-HCV agent, both as an adapter protein and as an eIF2α-kinase, and in cooperation with the di-ubiquitin-like protein ISG15. Developing pharmaceutical inhibitors of PKR may help in resolving some viral infections as well as stress-related damages.

SERPINB3 expression on B-cell surface in autoimmune diseases and hepatitis C virus-related chronic liver infection

SERPINB3 is a serine protease inhibitor with pleiotropic functions. It is involved in several physiological and pathological processes, where it appears to exert antiapoptotic effects. Little is known about its expression on immune system cells, the major players in mechanisms of viral defense and autoimmune disorders. The aim of this study was to characterize the expression of SERPINB3 on the surface of peripheral blood mononuclear cell subsets in both normal subjects and in patients with chronic viral infections and autoimmune diseases. Sixty-two patients were analyzed by flow cytometric analysis, including 45 with hepatitis C virus (HCV)-related chronic liver disease and 17 with systemic lupus erythematosus (SLE). SERPINB3 was expressed on B lymphocytes in 79% of the controls, in 32% of the HCV-infected patients and in none of the SLE patients. Surface localization of SERPINB3 was confirmed by confocal microscopy. SERPINB3 positivity was associated with CD27 reactivity (r = 0.98), but not to other activation molecules (CD69, CD71, CD86 and CXCR3). SERPINB3 is physiologically expressed on the surface of CD27(+) B lymphocytes, but its expression is reduced in HCV viral infection and not detectable in SLE patients. These results may suggest a role for SERPINB3 in B-cell defects typically found in viral infections and autoimmune disorders.

Cytokines and HCV-related disorders

Cytokines are intercellular mediators involved in viral control and liver damage being induced by infection with hepatitis C virus (HCV). The complex cytokine network operating during initial infection allows a coordinated, effective development of both innate and adaptive immune responses. However, HCV interferes with cytokines at various levels and escapes immune response by inducing a T-helper (Th)2/T cytotoxic 2 cytokine profile. Inability to control infection leads to the recruitment of inflammatory infiltrates into the liver parenchyma by interferon (IFN)-gamma-inducible CXC chemokine ligand (CXCL)-9, -10, and -11 chemokines, which results in sustained liver damage and eventually in liver cirrhosis. The most important systemic HCV-related extrahepatic diseases--mixed cryoglobulinemia, lymphoproliferative disorders, thyroid autoimmune disorders, and type 2 diabetes--are associated with a complex dysregulation of the cytokine/chemokine network, involving proinflammatory and Th1 chemokines. The therapeutical administration of cytokines such as IFN-alpha may result in viral clearance during persistent infection and reverts this process.

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

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

Interferon-stimulated gene pathways in the treatment of viral hepatitis

Viral hepatitis has been treated empirically for more than 30 years with interferon (IFN)-based therapies, although in the early days of the IFN era, very little was known regarding the mechanisms of action through which IFN acts and the strategies that viruses deploy to escape the antiviral state induced by the activation of the IFN system. Over the years, we have learned how key effector molecules in this system are expressed and interact. On the verge of novel, IFN-free regimens for viral hepatitis, we can take advantage of this huge bulk of research data in order to gain better understanding of how resistance to IFN develops in our patients, to use IFN more effectively in conjunction with other drugs and to devise new treatments.

Serum IP-10 Levels Correlate with the Severity of Liver Histopathology in Patients Infected with Genotype-1 HCV

BACKGROUND/AIMS

Interferon-γ-inducible protein 10 (IP-10) plays important roles in the pathogenesis of hepatitis C virus (HCV) infection. We investigated the association between serum IP-10 levels and liver pathology in patients with chronic HCV infection.

METHODS

The serum IP-10 concentration was assessed in 85 patients with chronic HCV infection using a solid phase sandwich enzyme-linked immunosorbent assay, and a liver biopsy specimen was obtained. The pathology was scored using the Knodell histologic activity index (HAI).

RESULTS

Of the 85 patients, 58 had genotype 1 HCV infection, 21 had genotype non-1, and 6 were undetermined. The serum IP-10 levels did not differ between patients infected with genotype 1 and genotype non-1 (p=0.472). In patients with genotype 1 infection, the total HAI score and the stage of fibrosis were highly correlated with the serum IP-10 level (r=0.555, r=0.578, p<0.001). Furthermore, the serum IP-10 concentrations of patients with severe fibrosis (stages 3, 4) were higher than those of patients with mild fibrosis (stages 0 to 2; 214.4 vs. 72.3 pg/mL, p=0.002) among patients with genotype 1 infection. However, in patients without genotype 1 infection, the histopathology was not associated with the serum IP-10 level. A multivariate analysis showed that serum IP-10 was an independent predictor of fibrosis (stages 3, 4) in patients with genotype 1 infection (odds ratio, 1.034; 95% confidence interval, 1.006 to 1.064; p=0.018).

CONCLUSIONS

Serum IP-10 concentration was significantly correlated with the severity of liver histology in genotype 1 HCV infection.

Redistribution of regulatory T-cells across the evolving stages of chronic hepatitis C

BACKGROUND

Hepatitis C virus infection frequently leads to chronic hepatitis, possibly evolving to end-stage liver disease and hepatocellular carcinoma. Regulatory T cells can affect antiviral immune response thus influencing the outcome of the disease.

AIM

To determine numeric and functional distribution of regulatory T cells expressing CD4+CD25hiFoxp3+ (T-regs) during the different stages of hepatitis C virus-related liver disease.

METHODS

90 hepatitis C viraemic patients and 50 healthy controls were included. Surface and intracellular (Foxp3) T-reg markers were evaluated by flow cytometry. Target cell proliferation and interferon-gamma production were evaluated in 37 HCV patients. In 16 cases intrahepatic distribution of Foxp3 by immuno-histochemistry was assessed.

RESULTS

T-regs were increased in hepatitis C virus infected patients and correlated inversely with aminotransferases and directly with MELD score and disease duration. A preserved inhibitory ability of interferon-gamma production was distinctive of patients with normal aminotransferases. Circulating T-regs did not correlate with intrahepatic distribution of Foxp3.

CONCLUSIONS

In chronic hepatitis C, selective expansion of peripheral T-regs in patients with normal aminotransferases and advanced disease suggests that, though a continual low level inflammation does not prevent liver disease progression, once cirrhosis has developed it may represent an attempt to prevent immuno-mediated decompensation.

Dysregulation of IFN system can lead to poor response to pegylated interferon and ribavirin therapy in chronic hepatitis C

BACKGROUND

Despite being expensive, the standard combination of pegylated interferon (Peg-IFN)-α and ribavirin used to treat chronic hepatitis C (CH) results in a moderate clearance rate and a plethora of side effects. This makes it necessary to predict patient outcome so as to improve the accuracy of treatment. Although the antiviral mechanism of genetically altered IL28B is unknown, IL28B polymorphism is considered a good predictor of IFN combination treatment outcome.

METHODOLOGY

Using microarray, we quantified the expression profile of 237 IFN related genes in 87 CH liver biopsy specimens to clarify the relationship between IFN pathway and viral elimination, and to predict patients' clinical outcome. In 72 out of 87 patients we also analyzed IL28B polymorphism (rs8099917).

PRINCIPAL FINDINGS

Five IFN related-genes (IFI27, IFI 44, ISG15, MX1, and OAS1) had expression levels significantly higher in nonresponders (NR) than in normal liver (NL) and sustained virological responders (SVR); this high expression was also frequently seen in cases with the minor (TG or GG) IL28B genotype. The expression pattern of 31 IFN related-genes also differed significantly between NR and NL. We predicted drug response in NR with 86.1% accuracy by diagonal linear discriminant analysis (DLDA).

CONCLUSION

IFN system dysregulation before treatment was associated with poor IFN therapy response. Determining IFN related-gene expression pattern based on patients' response to combination therapy, allowed us to predict drug response with high accuracy. This method can be applied to establishing novel antiviral therapies and strategies for patients using a more individual approach.

Danoprevir monotherapy decreases inflammatory markers in patients with chronic hepatitis C virus infection

Danoprevir is a potent and selective direct-acting antiviral agent that targets the protease activity of hepatitis C virus (HCV) NS3/4A. This agent results in a significant rapid decline in HCV RNA levels when it is used in monotherapy. The present study evaluated whether plasma concentrations of the inflammatory markers gamma interferon-inducible protein 10 (IP-10) and neopterin or the interferon-stimulated gene product 2'-5'-oligoadenylate synthetase (OAS-1) were correlated with the plasma HCV RNA concentration before or during 14-day danoprevir monotherapy. In contrast to pegylated interferon and ribavirin treatment, a higher baseline IP-10 concentration was positively correlated with a greater first-phase HCV RNA decline upon danoprevir administration. Changes in the IP-10 plasma concentration during danoprevir administration were also associated with categorical changes in HCV RNA concentration at days 7 and 14. The neopterin concentration appeared to be moderately decreased during danoprevir administration, although these changes were not statistically significant. However, changes in neopterin concentration showed a statistically significant correlation with changes in IP-10 concentration. Considerable variation in the OAS-1 concentration was observed before and during treatment, including in patients treated with placebo and/or patients with minimal virologic response. Overall, these results suggest that effective treatment with a direct-acting antiviral agent may reduce hepatic inflammation and that first-phase HCV RNA decline during treatment with an NS3/4A protease inhibitor is more robust in patients with high baseline IP-10 concentrations.

Toll-like receptor 7 rs179008/Gln11Leu gene variants in chronic hepatitis C virus infection

Hepatitis C virus (HCV) infection affects an estimated 3% of the world's population. The natural outcome of infection and the natural course of disease are highly variable. Sensing of viral single-stranded RNA (ssRNA) by Toll-like receptor 7 (TLR7) is likely involved in early pathogen detection and host response to viral infections. This study analyzed epidemiological and clinical data from 136 patients with HCV infection with regard to rs179008/Gln11Leu, a non-synonymous polymorphism within exon 3 of the X-linked TLR7 gene, the variant allele of which is suggested to code for a functionally impaired protein. Allele-specific transcript quantification (ASTQ) analyses in heterozygous females revealed individual skewed mosaicism in peripheral blood mononuclear cells (PBMCs). Thus, analyses were restricted to homo- and hemizygous individuals. Among the clinical and histological parameters studied, the variant allele T was found to be solely associated with the presence of portal lymphoid aggregates. Whereas hepatic viral load and expression of genes known to be induced in chronic HCV infection were not found to differ in patients with wild-type or variant TLR7 rs179008 genotype, significant lower gene expression of interleukin-29 (IL-29)/lambda(1) interferon (IFN-λ(1)) and both of its receptor subunits was found for T homo- and hemizygous patients. Irrespective of the minor differences in disease phenotype including hepatic viral load, natural, and alpha interferon (IFN-α)-mediated outcome of infection, and disease activity and progression, the significant differences in hepatic IL-29/IFN-λ(1) and IFN-λ receptor gene expression between TLR7 rs179008 T and A allele patients might have implications for responsiveness to future IFN-λ-based approaches.

Experimental models to study the immunobiology of hepatitis C virus

Effective host immune responses are essential for the control of hepatitis C virus (HCV) infection and persistence of HCV has indeed been attributed to their failure. In recent years, several in vitro and in vivo experimental models have allowed studies of host immune responses against HCV. Numerous observations derived from these models have improved our understanding of the mechanisms responsible for the host's ability to clear the virus as well as of the mechanisms responsible for the host's failure to control HCV replication. Importantly, several findings obtained with these model systems have been confirmed in studies of acutely or chronically HCV-infected individuals. Collectively, several mechanisms are used by HCV to escape host immune responses, such as poor induction of the innate immune response and escaping/impairing adaptive immunity. In this review, we summarize current findings from experimental models available for studies of the immune response targeting HCV and discuss the relevance of these findings for the in vivo situation in HCV-infected humans.

Differential expression of interferon-induced microRNAs in patients with chronic hepatitis C virus infection treated with pegylated interferon alpha

There have been reports of in-vitro interferon (IFN)-mediated antiviral activity against the hepatitis C virus (HCV) through microRNAs (miRNAs). The main aim of this study was to evaluate the expression of several miRNAs (miR-1, miR-30, miR-128, miR-196, miR-296) in peripheral blood mononuclear cells (PBMCs) from healthy individuals after in vitro IFN-treatment and in PBMCs from patients with chronic hepatitis C (CHC) before and 12 hours after the first injection of pegylated IFN alpha. We demonstrated that expression of these miRNAs could be recorded in PBMCs collected from healthy individuals before and after in-vitro IFN alpha treatment. Our analysis revealed that the levels of expression of all miRNAs investigated in patients with CHC were different to those in healthy individuals. When levels of the miRNAs were measured 12 hours after the first IFN injection, increases in expression levels of IFN-induced miRNAs were observed in 25-50% of patients, depending on the type of miRNA examined. No correlations were observed between HCV viral load, alanine aminotransferase status and expression of miRNA. Together these findings suggest that: (i) IFN alpha in-vitro treatment of PBMCs leads to a transcriptional induction of all miRNAs investigated; (ii) miRNAs can be induced differentially by IFN treatment in patients with HCV. Given the importance of miRNAs in defending the host against virus infections, it is possible that IFN-induced miRNAs may represent an important determinant of the clinical outcome of IFN therapy in HCV infection.

Inhibition of hepatitis C virus infection by interferon-gamma through downregulating claudin-1

Hepatitis C virus (HCV) is a serious global health threat and current medical treatment options are limited. Interferon (IFN)-gamma is an important proinflammatory cytokine with antiviral activity. However, the mechanism of IFN-gamma in anti-HCV infection remains unclear. In this study, we investigated the role of IFN-gamma on HCV infection of polarized Caco-2 cells using cell culture-derived HCV (HCVcc). We found that downregulation of claudin-1 (CLDN1) induced by IFN-gamma resulted in disruption of barrier function as demonstrated by measurement of transepithelial electrical resistance and dextran permeability. Further, results from confocal microscopy and Western blot analysis showed that in addition to the reduction of CLDN1 expression, IFN-gamma treatment also led to significant changes in the distribution of CLDN1, CD81, and scavenger receptor class B type I. Moreover, infection assays revealed that IFN-gamma-treated cells showed decreased susceptibility to HCVcc infection. These results suggest a novel mechanism that IFN-gamma may inhibit HCV infection by regulating CLDN1 expression and distribution of HCV receptors.

Possible recruitment of peripheral blood CXCR3+ CD27+ CD19+ B cells to the liver of chronic hepatitis C patients

It has been suggested that hepatitis C virus (HCV) infects not only hepatocytes but also immune cells, including B cells. HCV infection of B cells is the likely cause of B-cell dysregulation disorders such as mixed cryoglobulinemia, rheumatoid factor production, and B-cell lymphoproliferative disorders that may evolve into non-Hodgkin's lymphoma. To clarify the effects of chronic HCV infection on B-cell dynamics, peripheral B cells from chronic hepatitis C patients (CHC) were characterized. We found that the frequency of CD27(+) B cells, that is memory phenotype, was significantly reduced in the peripheral blood of CHC. At the same time, the amount of IFN-gamma-inducible protein-10 (IP-10), a CXCR3 ligand, was markedly elevated in the plasma of CHC. Furthermore, the CD27(+) B-cell population was found to highly express CXCR3 in CHC, thus suggesting that the CD27(+) B-cell population was recruited from peripheral blood to the inflammatory site of the liver of CHC, where IP-10 is produced. Immunohistochemical analyses of intrahepatic lymphocytes indicated that CXCR3(+) B cells were infiltrated in the liver of CHC. Our results thus offer new insight into the role of memory B cells in the HCV pathogenesis.

Natural killer cells are polarized toward cytotoxicity in chronic hepatitis C in an interferon-alfa-dependent manner

BACKGROUND & AIMS

Patients with chronic hepatitis C virus (HCV) infection display great variability in disease activity and progression. Although virus-specific adaptive immune responses have been characterized extensively and found to be impaired in chronic hepatitis C, the role of innate immune responses in disease activity and progression of chronic hepatitis C is not well understood.

METHODS

We studied 42 HCV-infected patients and 12 healthy uninfected controls.

RESULTS

We found an increased frequency of natural killer (NK) cells expressing tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), NKp44, NKG2C, and CD122 in chronic hepatitis C as compared with healthy controls (P < .05 for all markers) and stronger activation of NK cells in the liver than in the blood (P < .05). This NK cell phenotype was associated with polarization of NK cell function toward CD107a expression as a marker of degranulation, but with not increased interferon (IFN)-gamma production of CD56(dim) NK cells. The polarized NK cell phenotype correlated with alanine aminotransferase levels (r(2) = 0.312, P = .03). To investigate whether in vivo exposure of NK cells to HCV-induced type I IFN was causing this NK cell phenotype, peripheral blood mononuclear cells from 10 healthy controls and 8 HCV-infected patients were stimulated in the presence of IFN-alfa, which resulted in increased NK cell expression of TRAIL and CD107a (P < .001), but not IFN-gamma.

CONCLUSIONS

Collectively, these results describe a polarized NK cell phenotype induced by chronic exposure to HCV-induced IFN-alfa. This phenotype may contribute to liver injury through TRAIL expression and cytotoxicity, whereas the lacking increase in IFN-gamma production may facilitate the inability to clear HCV.

Hepatitis C virus virology and new treatment targets

Hepatitis C virus (HCV) infection is the leading cause of chronic liver disease. An estimated 130 million people worldwide are persistently infected with HCV. Almost half of patients who have chronic HCV infection cannot be cured with the standard treatment consisting of pegylated IFN-alpha and ribavirin. For those patients who do not respond to this standard antiviral therapy, there is currently no approved treatment option available. Recent progress in structure determination of HCV proteins and development of a subgenomic replicon system enables the development of a specifically targeted antiviral therapy for hepatitis C. Many HCV-specific compounds are now under investigation in preclinical and clinical trials.

Role of chemokines and their receptors in viral persistence and liver damage during chronic hepatitis C virus infection

Chemokines produced in the liver during hepatitis C virus (HCV) infection induce migration of activated T cells from the periphery to infected parenchyma. The milieu of chemokines secreted by infected hepatocytes is predominantly associated with the T-helper cell/Tc1 T cell (Th1/Tc1) response. These chemokines consist of CCL3 (macrophage inflammatory protein-1 alpha; MIP-1 alpha), CCL4 (MIP-1 beta), CCL5 (regulated on activation normal T cell expressed and secreted; RANTES), CXCL10 (interferon-gamma-inducible protein-10; IP-10), CXCL11 (interferon-inducible T-cell alpha chemoattractant; I-TAC), and CXCL9 (monokine induced by interferon gamma; Mig) and they recruit T cells expressing either CCR5 or CXCR3 chemokine receptors. Intrahepatic and peripheral blood levels of these chemokines are increased during chronic hepatitis C. The interaction between chemokines and their receptors is essential in recruiting HCV-specific T cells to control the infection. When the adaptive immune response fails in this task, non-specific T cells without the capacity to control the infection are also recruited to the liver, and these are ultimately responsible for the persistent hepatic damage. The modulation of chemokine receptor expression and chemokine secretion could be a viral escape mechanism to avoid specific T cell migration to the liver during the early phase of infection, and to maintain liver viability during the chronic phase, by impairing non-specific T cell migration. Some chemokines and their receptors correlate with liver damage, and CXCL10 (IP-10) and CXCR3 levels have shown a clinical utility as predictors of treatment response outcome. The regulation of chemokines and their receptors could be a future potential therapeutic target to decrease liver inflammation and to increase specific T cell migration to the infected liver.

Endocrine manifestations of hepatitis C virus infection

Chronic infection with hepatitis C virus (HCV) can result in both hepatic and extrahepatic disease and endocrine dysfunction represents an important class of HCV-related extrahepatic disease. The most frequently occurring--and clinically important--of these endocrine disorders are thyroid disease and type 2 diabetes mellitus. In this Review, we evaluate the evidence in support of a link between HCV infection and endocrine-system dysfunction, and discuss potential pathophysiological mechanisms. A meta-analysis of the literature has revealed significant associations between chronic HCV infection, thyroid autoimmunity and hypothyroidism. Furthermore, a high prevalence of thyroid cancer has been reported in HCV-positive patients. Several clinicoepidemiological studies have demonstrated that chronic HCV infection could lead to the development of type 2 diabetes mellitus, possibly as a result of HCV-induced metabolic disturbances. Some researchers have postulated that a type 1 T-helper -cell mediated immune response underpins the association of chronic HCV infection with endocrine disease. Indeed, the available data suggest that a common immunological, type 1 T-helper cell pattern of cytokine expression and activation (via interferon-gamma) could provide the pathophysiological basis for this association. Nonetheless, additional studies will be necessary to elucidate fully all the mechanisms involved in HCV-related endocrine dysfunction.

Role of chemokines and their receptors in viral persistence and liver damage during chronic hepatitis C virus infection

Chemokines produced in the liver during hepatitis C virus (HCV) infection induce migration of activated T cells from the periphery to infected parenchyma. The milieu of chemokines secreted by infected hepatocytes is predominantly associated with the T-helper/T-cytotoxic type-1 cell (Th1/Tc1) response. These chemokines consist of CCL3 (macrophage inflammatory protein-1α; MIP-1α), CCL4 (MIP-1β), CCL5 (regulated on activation normal T cell expressed and secreted; RANTES), CXCL10 (interferon-γ−inducible protein-10; IP-10), CXCL11 (interferon-inducible T-cell α chemoattractant; I-TAC), and CXCL9 (monokine induced by interferon γ; Mig) and they recruit T cells expressing either CCR5 or CXCR3 chemokine receptors. Intrahepatic and peripheral blood levels of these chemokines are increased during chronic hepatitis C. The interaction between chemokines and their receptors is essential in recruiting HCV-specific T cells to control the infection. When the adaptive immune response fails in this task, non-specific T cells without the capacity to control the infection are also recruited to the liver, and these are ultimately responsible for the persistent hepatic damage. The modulation of chemokine receptor expression and chemokine secretion could be a viral escape mechanism to avoid specific T cell migration to the liver during the early phase of infection, and to maintain liver viability during the chronic phase, by impairing non-specific T cell migration. Some chemokines and their receptors correlate with liver damage, and CXCL10 (IP-10) and CXCR3 levels have shown a clinical utility as predictors of treatment response outcome. The regulation of chemokines and their receptors could be a future potential therapeutic target to decrease liver inflammation and to increase specific T cell migration to the infected liver.

Interferon-alpha therapy does not modulate hepatic expression of classical type I interferon inducible genes

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease. Treatment with interferon-alpha(2) (IFN-alpha(2)) can induce viral clearance and marked biochemical and histological improvement. IFN-alpha(2) treatment has been shown to stimulate the expression of type I IFN regulated genes in peripheral blood mononuclear cells (PBMCs) of hepatitis C patients; however, whether it affects hepatic expression remains unknown. This study thus aimed at comparing hepatic gene expression with particular emphasis on type I IFN inducible genes in patients with chronic hepatitis C before and during an IFN-alpha(2) monotherapy. Responsiveness to IFN-alpha(2) therapy was monitored by determining serum and hepatic viral load. Differential gene expression analysis was performed by two different techniques, namely suppression subtractive hybridization (SSH) and differential display (DD). Expression of two prototype type I IFN regulated genes was quantified in further PBMC and liver samples. Among different genes found to be up-regulated during an effective, that is, virus clearing, IFN-alpha treatment, only a single one was identified which can be accounted to type I IFN responsive genes. Parallel quantitative real time PCR analyses demonstrated significant induction of the type I IFN regulated genes MxA and PKR in PBMC, but not in the liver. Taken together, while IFN-alpha treatment leads to the induction of type I IFN regulated genes in PBMC, such an induction appears not to occur in the liver of hepatitis C patients. The mechanism by which IFN-alpha treatment causes viral clearance might be independent of hepatic activation of type I IFN regulated genes.

Immunopathogenesis of HCV-related endocrine manifestations in chronic hepatitis and mixed cryoglobulinemia

Hepatitis C Virus (HCV) is known to be responsible for both hepatic and extrahepatic diseases (HCV-related extrahepatic diseases = HCV-EHDs). The most important systemic HCV-EHDs are mixed cryoglobulinemia and lymphoproliferative disorders, while the most frequent and clinically important endocrine HCV-EHDs are thyroid disorders and type 2 diabetes mellitus (T2D). From a meta-analysis of the literature a significant association between HCV infection and thyroid autoimmunity and hypothyroidism has been reported. A high prevalence of thyroid cancer has been reported, too. Furthermore, several clinical epidemiologic studies have reported that HCV infection is associated to T2D. Many studies have linked Th1 immune response with HCV infection, thyroid autoimmunity, or diabetes. These findings suggest that a possible common immunological Th1 pattern could be the pathophysiological base of the association of HCV-EHDs, with thyroid autoimmunity and T2D. In fact, HCV infection of thyrocytes or beta-cells may act by upregulating CXCL10 secretion in these cells that is responsible for Th1 lymphocyte recruitment. Th1 response leads to increased IFNgamma and TNFalpha production that in turn stimulates CXCL10 secretion by the target cells, thus perpetuating the immune cascade. This process may lead to the appearance of thyroid autoimmune disorders or T2D in genetically predisposed subjects.

Regulatory polymorphisms in the promoter of CXCL10 gene and disease progression in male hepatitis B virus carriers

BACKGROUND & AIMS

The importance of expression of interferon gamma-inducible protein of 10 kilodaltons (IP-10, CXCL10) during chronic hepatitis B virus (HBV) infection has been recently emphasized. In this report, we investigated whether the naturally occurred sequence variations in the CXCL10 gene impact liver damage and disease progression of chronic HBV infection.

METHODS

A hospital-based case-control study was conducted, and a total of 613 and 1787 unrelated Han Chinese HBV carriers were recruited from Beijing and Chongqing, respectively. We systematically screened sequence variations in the CXCL10 gene and examined the association between the variations in this gene and susceptibility to disease progression of chronic HBV infection in Chinese populations from Beijing and Chongqing. Functional analyses were conducted to verify the biological significances of the associated genetic variation.

RESULTS

We identified that the polymorphism G-201A, located in the promoter region of CXCL10, was associated with susceptibility to disease progression in male HBV carriers (dominant model; odds ratio, 1.53; P = .001). Functional analyses show that the G-201A polymorphism alters the binding affinity of nuclear protein and regulates CXCL10 expression. We observed higher CXCL10 transcription in interferon gamma-stimulated peripheral blood mononuclear cells with the disease-susceptible genotypes. Enzyme-linked immunosorbent assay and immunohistochemical analysis showed augmented CXCL10 production in serum and liver tissues of progressed HBV carriers.

CONCLUSIONS

The novel regulatory polymorphism G-201A [corrected] in the promoter of CXCL10 gene could be a part of the genetic variation underlying the susceptibility of individuals to disease progression of chronic HBV infection.

Intrahepatic mRNA expression in hepatitis C virus and HIV/hepatitis C virus co-infection: infiltrating cells, cytokines, and influence of HAART

OBJECTIVE

Liver disease is more progressive in HIV/hepatitis C virus (HCV) co-infection than in HCV infection alone. This accelerated pathogenesis is probably influenced by differences in the composition of infiltrating inflammatory cells and the local release of inflammatory and profibrogenic cytokines.

METHODS

Using quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) we studied intrahepatic messenger RNA levels of cytokines and cellular markers defining distinct subsets of inflammatory cells in liver biopsies from 33 HCV-mono-infected and 40 HIV/HCV-co-infected patients.

RESULTS

Despite their well preserved peripheral blood CD4 cell counts (median 598 cells/microl), HIV/HCV-co-infected patients displayed significantly lower CD4 mRNA levels than HCV-mono-infected patients, whereas increased mRNA levels of CD3epsilon, TCRalpha, CD8alpha and CD8beta suggested intrahepatic enrichment of CD8 T cells in HIV co-infection. Intrahepatic mRNA levels of the inflammatory cytokines interferon gamma (IFN-gamma), regulated upon activation, normal T-cell expressed and secreted (RANTES, CCL5), macrophage inflammatory protein 1 alpha (CCL3) and interferon-inducible protein 10 (CXCL10) were significantly higher in HIV-positive than in HIV-negative patients, whereas mRNA levels of the profibrogenic cytokines macrophage chemoattractant protein 1 (CCL2), secondary lymphochemokine (CCL21) and stroma-derived factor 1 (CXCL12) did not differ between the two groups. All changes were less pronounced in the subgroup of HIV-positive patients receiving antiretroviral treatment (HAART) than in untreated HIV-positive patients.

CONCLUSION

The accelerated liver disease observed in HIV/HCV-co-infected patients might reflect enhanced intrahepatic inflammatory responses rather than increased local transcription of directly profibrogenic cytokines.