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Micronutrient deficiencies develop for a variety of reasons, whether geographic, socioeconomic, nutritional, or as a result of disease pathologies such as chronic viral infection. As micronutrients are essential for a strong immune response, deficiencies can significantly dampen both the innate and the adaptive arms of antiviral immunity. The innate immune response in particular is crucial to protect against hepatitis C virus (HCV), a hepatotropic virus that maintains chronic infection in up to 80% of individuals if left untreated. While many micronutrients are required for HCV replication, an overlapping group of micronutrients are also necessary to enact a potent immune response. As the liver is responsible for the storage and metabolism of many micronutrients, HCV persistence can influence the micronutrients' steady state to benefit viral persistence both directly and by weakening the antiviral response. This review will focus on common micronutrients such as zinc, iron, copper, selenium, vitamin A, vitamin B12, vitamin D and vitamin E. We will explore their role in the pathogenesis of HCV infection and in the response to antiviral therapy. While chronic hepatitis C virus infection drives deficiencies in micronutrients such as zinc, selenium, vitamin A and B12, it also stimulates copper and iron excess; these micronutrients influence antioxidant, inflammatory and immune responses to HCV.

Recently, single nucleotide polymorphisms, in the vicinity of the interferon lambda 3 (IFNL3) gene have been identified as the strongest predictor of spontaneous and treatment induced clearance of hepatitis C virus (HCV) infection. Since then, increasing evidence has implicated the innate immune response in mediating the IFNL3 genotype effect. Dendritic cells (DCs) are key to the host immune response in HCV infection and their vital role in the IFNL3 genotype effect is emerging. Reports have identified subclasses of DCs, particularly myeloid DC2s and potentially plasmacytoid DCs as the major producers of IFNL3 in the setting of HCV infection. Given the complexities of dendritic cell biology and the conflicting current available data, this review aims to summarize what is currently known regarding the role of dendritic cells in HCV infection and to place it into context of what is know about lambda interferons and dendritic cells in general.

Unlabelled: Ribavirin (RBV) is an important component of interferon (IFN)-based and direct antiviral treatment regimens for hepatitis C virus (HCV) infection. Immunomodulation, in particular improvement of the host IFN response, has been proposed as RBV's mechanism of action. Natural killer (NK) cells are sensitive biomarkers for IFN-α/β receptor signaling, as NK cell cytotoxicity and IFN-γ production are regulated by signal transducer and activator of transcription (STAT)1- and STAT4-phosphorylation, respectively. Specifically, pSTAT1-dependent NK cell cytotoxicity increases and pSTAT4-dependent IFN-γ production decreases in response to endogenous, virus-induced IFN-α and during IFN-α-based therapy. To assess whether RBV has a direct effect on NK cells and/or improves the IFN-γ response of NK cells in the presence of IFN-α, we prospectively studied 22 HCV patients with and 32 patients without 4 weeks of RBV pretreatment, who all received subsequent pegylated (Peg)IFN/ribavirin combination therapy. During RBV pretreatment, both the frequency of CD56(dim) NK cells with cytotoxic effector functions and the frequency of CD56(bright) NK cells with the capacity to produce IFN-γ decreased (P = 0.049 and P = 0.001, respectively). In vitro or in vivo exposure of NK cells to RBV improved the pSTAT4 (P < 0.01) but not pSTAT1 response of NK cells to subsequent stimulation with IFN-α. This was associated with an increase in IFN-γ production but not cytotoxicity of NK cells during subsequent IFN-α-based therapy. The frequency of IFN-γ-producing NK cells was greater in fast second-phase virological responders than in slow responders., Conclusion: RBV enhances the pSTAT4 and IFN-γ response of NK cells to IFN-α-stimulation., (Published 2014. This article is a U.S. Government work and is in the public domain in the USA.)

Common IFN lambda 3 (IFNL3) variants have been demonstrated to affect spontaneous and treatment-induced clearance of hepatitis C virus (HCV) infection. The functional basis of these genetic variants has yet to be determined. Data examining the effect of IFNL3, specifically, in innate immune cells is lacking. Here, we determined the expression of IFNL3 and its receptor IFNLR1 in blood immune cell subsets and in HCV-infected livers. Next we assessed their sensitivity to IFNL3. All participants were genotyped for the IFNL3 SNPs rs8099917 and rs12979860. Importantly, unstimulated blood immune cells express significantly higher levels of IFNL3 than HCV liver biopsies. Plasmacytoid dendritic cells (pDCs) are the predominant producers of IFNLR1, especially in response to IFN-α. PBMCs, monocytes and pDCs all respond to IFNL3 based on MxA up-regulation. No differences in IFNL3 expression levels between rs8099917 or rs12979860 genotypes were detected. This is the first study to show peripheral blood pDCs to be the main producers of IFNL3, especially compared with HCV-infected livers. This makes innate immune cells the key players in determining the functional significance of INFL3 polymorphisms in patients with HCV., (© The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.)

In the past 2 years the ability to successfully eradicate chronic HCV infection has been substantially enhanced by two landmark scientific breakthroughs. Firstly, the advent of HCV-specific direct-acting antiviral (DAA) compounds has resulted in a significant increase in sustained virological response rates in HCV genotype-1-infected treatment-naive patients and in non-responders to prior pegylated interferon and ribavirin therapy. Secondly, the identification of single nucleotide polymorphisms near the interleukin 28B (IL28B) gene that potently influence spontaneous and treatment-induced recovery from HCV infection has improved our understanding of hepatitis C pathogenesis, has helped spur the development of novel antiviral therapies and has provided a tool for pretreatment decision making in the context of genotype 1 HCV infection. In light of these advances, we review the interaction between these two discoveries and discuss the role of IL28B genotyping prior to treatment initiation in the context of both standard therapy and the newly approved DAA-based regimens. The role of IL28B genotyping is particularly relevant as DAAs are more expensive and carry a higher risk for anaemia and other drug-related side effects, while decision-making based on IL28B genotype may permit non-DAA-based treatment algorithms.

Background: To date, drug response genes have not proved as useful in clinical practice as was anticipated at the start of the genomic era. An exception is in the treatment of chronic hepatitis C virus (HCV) genotype 1 infection with pegylated interferon-alpha and ribavirin (PegIFN/R). Viral clearance is achieved in 40%-50% of patients. Interleukin 28B (IL28B) genotype predicts treatment-induced and spontaneous clearance. To improve the predictive value of this genotype, we studied the combined effect of variants of IL28B with human leukocyte antigen C (HLA-C), and its ligands the killer immunoglobulin-like receptors (KIR), which have previously been implicated in HCV viral control., Methods and Findings: We genotyped chronic hepatitis C (CHC) genotype 1 patients with PegIFN/R treatment-induced clearance (n = 417) and treatment failure (n = 493), and 234 individuals with spontaneous clearance, for HLA-C C1 versus C2, presence of inhibitory and activating KIR genes, and two IL28B SNPs, rs8099917 and rs12979860. All individuals were Europeans or of European descent. IL28B SNP rs8099917 "G" was associated with absence of treatment-induced clearance (odds ratio [OR] 2.19, p = 1.27×10(-8), 1.67-2.88) and absence of spontaneous clearance (OR 3.83, p = 1.71×10(-14), 2.67-5.48) of HCV, as was rs12979860, with slightly lower ORs. The HLA-C C2C2 genotype was also over-represented in patients who failed treatment (OR 1.52, p = 0.024, 1.05-2.20), but was not associated with spontaneous clearance. Prediction of treatment failure improved from 66% with IL28B to 80% using both genes in this cohort (OR 3.78, p = 8.83×10(-6), 2.03-7.04). There was evidence that KIR2DL3 and KIR2DS2 carriage also altered HCV treatment response in combination with HLA-C and IL28B., Conclusions: Genotyping for IL28B, HLA-C, and KIR genes improves prediction of HCV treatment response. These findings support a role for natural killer (NK) cell activation in PegIFN/R treatment-induced clearance, partially mediated by IL28B.

In hepatitis C virus (HCV) infection antiviral T cells express the CC chemokine receptor 5 (CCR5). Their recruitment to the liver is an important step in the immune response. A 32 base pair deletion in the CCR5 gene leads to reduced expression and total loss of CCR5 in CCR5-n32 heterozygous and homozygous subjects, respectively. However, the role of this mutation for antiviral immunity remains unclear. Here, we analysed proliferation, IFN-gamma and IL-4 secretion (ELISpot) induced by the HCV antigens core, NS3, NS4, and NS5a in 21 anti-HCV-positive haemophiliac patients in relationship to their CCR5 genotypes (CCR5 wildtype n = 10, CCR5-n32 heterozygous n = 5 and CCR5-n32 homozygous n = 6). Furthermore, T cell migration in response to the CCR5 ligands CCL3, -4 and -5 was studied. Overall IFN-gamma responses to HCV proteins were only slightly greater in CCR5 wild-type patients than in CCR5-n32 carriers (0.6 versus 0.24 SFC/10(4) PBMC; p = 0.043). This difference was consistently seen with all tested HCV antigens. In contrast, neither T cell migration, nor PBMC proliferation, nor IL-4 production differed between CCR5 genotypes. Interruption of the CCR5 signalling pathway due to CCR5-n32 may potentially result in subtle reduction of HCV specific IFN-gamma responses in anti-HCV-positive haemophiliac patients.

The C-type lectin DC-SIGNR has been shown to bind hepatitis C virus (HCV). Here, we analysed the tandem-repeat polymorphism of the DC-SIGNR gene with respect to intraindividual HCV replication. In a cross-sectional comparison HCV-infected patients (n = 430) and healthy subjects (n = 100) were genotyped for the DC-SIGNR polymorphism using PCR. The distribution of DC-SIGNR alleles did not differ significantly between the two groups. However, HCV-infected patients with 5-, 6-, and 7-repeat alleles had higher HCV-RNA levels when compared with carriers of 4- and 9-repeat alleles (P < 0.05). Thus, the DC-SIGNR polymorphism might affect HCV loads supporting the concept that DC-SIGNR contributes to HCV replication efficacy.

Hepatitis C virus (HCV) infection has been shown to be associated with reduced expression of the CC chemokine receptor (CCR) 5, and reduced responsiveness of lymphocytes to chemokines. However, the mechanism by which HCV alters CCR5 expression remains unclear. Here, we investigated whether altered CCR5 expression in hepatitis C results from interactions of CD81 with the HCV E2 protein. Peripheral blood mononuclear cells (PBMC) from HCV-negative individuals were prepared by Ficoll density gradient separation. PBMC subpopulations (CD4+, CD8+ lymphocytes, CD19+ B cells, natural killer (NK) cells and monocyte-derived dendritic cells) were isolated and stimulated with immobilized HCV E2, and changes in CCR5 expression and CC-chemokine secretion were determined. Migration assays were performed using a 5-microm nitrocellulose filter microchamber system according to the manufacturer's recommendations. Exposure of PBMC to HCV E2 induced a dose-dependent release of regulated on activation normal T-cell-expressed and secreted (RANTES), down-regulation of CCR5 expression and intracellular accumulation of CCR5. This effect was blocked by preincubation of PBMC with anti-CD81. RANTES release following exposure to HCV E2 was mainly attributable to CD8+ cells. After exposure to HCV E2 markedly fewer CD8-positive lymphocytes were attracted by RANTES when compared with CD8+ cells that were studied in the absence of HCV E2. Our results suggest that interaction of HCV E2 with CD81 leads to increased RANTES secretion by CD8+ lymphocytes which induces down-regulation of CCR5 surface via receptor internalization resulting in altered lymphocyte migration.

An effective immune response to hepatitis C virus (HCV) infection requires efficient recruitment and activation of inflammatory cells to the liver, the site of infection. Chemokines are critically involved in this process, since they exert both chemotactic and immunoregulatory actions. In particular, the interaction between chemokines CCL3 (MIP-1alpha), CCL4 (MIP-1beta) and CCL5 (RANTES) and their receptor, CC-chemokine receptor 5 (CCR5), may be critical in regulating T cell functions by mediating recruitment, polarization, activation and differentiation of antiviral type 1 cytokine secreting T helper and cytotoxic T cells. A 32 bp deletion in the encoding region of CCR5 leads to complete loss of the functional CCR5 receptor in subjects homozygous for this mutation and decreased expression in heterozygous patients. This fact provides the unique opportunity to study the role of the CCR5 receptor in chronic hepatitis C infection by comparing immune responses between HCV infected CCR5-Delta32 carriers and CCR5 wild-type patients. This article will summarize and discuss the available data with respect to possibly altered disease susceptibility, clinical course and treatment outcomes associated with the CCR5-Delta32 mutation in hepatitis C.