The predictive value of IL28B gene polymorphism for spontaneous clearance in a single source outbreak cohort is limited in patients carrying the CCR5Δ32 mutation.

BACKGROUND & AIMS: The CCR5Δ32 mutation has been suspected to adversely affect outcomes of HCV infection, although reports have remained controversial. Here, we investigated the relative genetic contributions of the CCR5Δ32 deletion and the IL28B rs12979860 polymorphisms to spontaneous clearance of hepatitis C in a single-source outbreak. METHODS: We retrieved 396 Caucasian women (119 women with spontaneous HCV clearance) who had been infected with HCV genotype 1-contaminated anti-D immunoglobulin in 1978, and determined their IL28B and CCR5 alleles. RESULTS: IL28B CC, CT, and TT genotypes were found in 35.4%, 50%, and 14.6% of patients and corresponded to spontaneous clearance rates of 50%, 21.2%, and 12.1% (Chi(2)=38.7, p=5.0×10(-10)), respectively. CCR5 WT/WT, WT/Δ32, and Δ32/Δ32 genotypes were observed in 76%, 22.7%, and 1.3% of patients and corresponded to clearance rates of 33.2%, 21.2%, and 0% (Chi(2)=6.9, p=0.009), respectively. In a stepwise forward-conditional multivariate regression model both CCR5 (OR 2.1, p=0.01 for WT/WT) and IL28B genetic variants (OR 4.3, p=4.6×10(-10) for the C/C genotype) were identified as independent predictors of spontaneous HCV clearance. Importantly, favorable response rates were associated with the IL28B CC genotype only in CCR5 wild-type homozygous women, while HCV clearance in CCR5Δ32 carriers remained poor even in patients with the rs12979860 CC genotype. CONCLUSIONS: Both IL28B rs1297860 and CCR5Δ32 allelic variants are independent genetic determinants of spontaneous HCV clearance. The variable relative distribution between IL28B rs1297860 and CCR5Δ32 allelic variants in different populations may have masked the role of the CCR5Δ32 mutation in some studies.

HLA class I allele associations with HCV genetic variants in patients with chronic HCV genotypes 1a or 1b infection.

BACKGROUND & AIMS: The adaptive immune response against hepatitis C virus (HCV) is significantly shaped by the host's composition of HLA-alleles with the consequence that the HLA phenotype is a critical determinant of viral evolution during adaptive immune pressure. In the present study, we aimed to identify associations of HLA class I alleles with HCV subtypes 1a and 1b genetic variants. METHODS: The association between HCV genetic variants and specific HLA-alleles was investigated in a cohort of 159 patients with chronic HCV genotypes 1a- and 1b-infection who were treated with pegylated interferon-alfa 2b and ribavirin in a prospective controlled trial for 48 weeks by direct sequencing of the genes encoding the HCV proteins E2, NS3, and NS5B and by HLA class I-genotyping of patients. HCV genetic variants were associated with specific HLA-alleles and the binding strength of accordant amino acid sequences to the corresponding HLA-allele was assessed by using the SYFPEITHI-algorithm. RESULTS: Overall, associations between HLA class I alleles and HCV sequence variation were rare. Five unknown HLA class I-associated viral genetic variations were identified, which in part affected the binding of predicted HCV CD8+ T cell epitopes to the respective HLA-allele. In addition, different patterns of HLA class I-allele/HCV sequence associations between the two subtypes were observed. CONCLUSIONS: We identified several unknown HLA class I-restricted HCV variants which in part impair binding to predicted HCV CD8+ T cell epitopes with remarkable differences between HCV subtypes 1a and 1b quasispecies.

Regulation of NK cell trafficking by CD81.

NK cells, a heterogeneous sub-population of lymphocytes, are critically involved in the regulation of both innate and adaptive immune responses in humans. Besides their participation in the control of tumors and viral infections, they also regulate inflammatory processes, mediating both beneficial and detrimental effects. To effectively fulfil their role in immune surveillance, proper trafficking of NK cells is essential. However, the mechanisms and factors governing NK cell recruitment are only poorly dissected. Here, we describe the functional role of tetraspanins, a family of evolutionary conserved cell-surface proteins, in modulating migration and transmigration of human NK cells. We demonstrate expression of various tetraspanins on NK cells. Furthermore, we show that stimulation of the NK cell-expressed tetraspanin CD81 induces phosphorylation of ezrin/radixin/moesin proteins and leads to NK cell polarization thereby facilitating NK cell migration toward various chemokines/cytokines. Finally, we provide evidence for a role of CD81 in promoting adhesion of NK cells to components of the extracellular matrix, a prerequisite for extravasation of lymphocytes in inflamed tissues. Thus, our data suggest that the tetraspanin CD81 is importantly involved in the regulation of NK cell recruitment.

The HLA-E(R)/HLA-E(R) genotype affects the natural course of hepatitis C virus (HCV) infection and is associated with HLA-E-restricted recognition of an HCV-derived peptide by interferon-gamma-secreting human CD8(+) T cells.

Recently, we showed chronic hepatitis C to be associated with increased expression of HLA-E and identified peptide hepatitis C virus (HCV) core amino acids 35-44 as a ligand for HLA-E that stabilizes HLA-E expression, favoring inhibition of natural killer cell cytotoxicity. Here we describe HLA-E-restricted recognition of peptide HCV core amino acids 35-44 by CD8(+) T cells. Frequency of HLA-E-restricted responses was significantly higher in patients homozygous for the HLA-E(R) allele (60% vs 38%; P = .038). Moreover, we found that the HLA-E(R) allelic variant confers protection against chronic infection with HCV genotypes 2 and 3. Taken together, our data indicate an important immunomodulating function of HLA-E in hepatitis C.

The transforming growth factor-beta high-producer genotype is associated with response to hepatitis C virus-specific therapy in HIV-positive patients with acute hepatitis C.

BACKGROUND: Coinfection with the hepatitis C virus (HCV) in HIV-positive patients is an emerging health problem. The factors affecting response to HCV-specific therapy are poorly understood but may involve host genetic factors. HCV NS5A-induced inhibition of transforming growth factor-beta signaling has been suggested as a potential mechanism involved in HCV pathogenesis. Transforming growth factor-beta, a multifunctional cytokine, displays gene polymorphisms (transforming growth factor-beta codon 10T/C and codon 25G/C) associated with differential cytokine secretion. Here, we studied whether transforming growth factor-beta gene polymorphisms affect treatment response in HCV/HIV coinfection. METHODS: Transforming growth factor-beta genotypes were determined in 60 HIV-positive patients with acute hepatitis C treated with pegylated interferon-alpha. Patients were classified into those with a high-producer genotype and others with non-high-producer genotypes. Rates of sustained virological responses were compared between high-producer and non-high-producer patients. As a control, 100 healthy, 201 HIV(+)/HCV(-), and 148 HCV(+)/HIV(-) subjects were studied. RESULTS: Transforming growth factor-beta genotype distribution did not differ significantly between the groups. In HIV/HCV coinfection carriers of the transforming growth factor-beta high-producer genotype had significantly higher sustained virological response rates than patients with a transforming growth factor-beta non-high-producer genotype (75 vs. 41.7%; P = 0.039). In a forward-conditional stepwise regression model, transforming growth factor-beta high-producer genotype was confirmed as an independent positive predictor for sustained virological response in interferon-alpha therapy (odds ratio, 4.4; 95% confidence interval, 1.5-13.4; P = 0.009). CONCLUSION: Response rates to interferon-alpha therapy are enhanced in acute HCV-infected HIV-positive patients carrying the transforming growth factor-beta 'high-producer' genotype. This finding may indicate that a transforming growth factor-beta 'high-producer' state can partially compensate HCV NS5A-induced inhibition of transforming growth factor-beta signaling.