Suppression of ribosomal protein synthesis and protein translation factors by Peg-interferon alpha/ribavirin in HCV patients blood mononuclear cells (PBMC).

BACKGROUND: We have previously reported the induction of many interferon stimulated genes (ISGs) in PBMC collected from patients infected with HCV at various times after initiation of interferon-ribavirin treatment using DNA microarrays to identify changes in gene expression with time. Almost as many genes are down regulated (suppressed) during interferon-ribavirin treatment as are up regulated. METHODS: DNA microarrays were analyzed by different software, including MAS5 (Affymetrix-Kegg) and GSEA (gene set enrichment analysis) to identify specific pathways both up regulated and down regulated. Data was assessed from a clinical trial, which was a microarray analysis from 68 patients. RESULTS: Up regulated genes included genes associated with NF-kb, toll like receptor cytokine -cytokine interaction, and complement and adhesion pathways. The most prominent pathway down regulated was that for ribosomal structural proteins, and eukaryotic translational factors. Down regulation of ribosomal protein genes continued through the treatment up to the last measurement, which was at day 28. CONCLUSIONS: This suppression of the protein synthetic apparatus might explain the long-term side effects of interferon-ribavirin, and explain a non-specific effect of interferon-ribavirin on viral protein synthesis. There was no evidence for unique transcription factors or micro RNA involvement.

Cyclic changes in gene expression induced by Peg-interferon alfa-2b plus ribavirin in peripheral blood monocytes (PBMC) of hepatitis C patients during the first 10 weeks of treatment.

BACKGROUND AND AIMS: This study determined the kinetics of gene expression during the first 10 weeks of therapy with Pegylated-interferon-alfa2b (PegIntron) and ribavirin (administered by weight) in HCV patients and compared it with the recently completed Virahep C study 12 in which Peginterferon-alfa2a (Pegasys) and ribavirin were administered. METHODS: RNA was isolated from peripheral blood monocytes (PBMC) from twenty treatment-naïve patients just before treatment (day 1) and at days 3, 6, 10, 13, 27, 42 and 70 days after treatment. Gene expression at each time was measured using Affymetrix microarrays and compared to that of day 1. RESULTS: The expression of many genes differed significantly (p

Global effect of PEG-IFN-alpha and ribavirin on gene expression in PBMC in vitro.

Using oligonucleotide microarrays, we have examined the expression of 22,000 genes in peripheral blood cells treated with pegylated interferon-alpha2b (PEG-IFN-alpha) and ribavirin. Treatment with ribavirin had very little effect on gene expression, whereas treatment with PEG-IFN-alpha had a dramatic effect, modulating the expression of approximately 1000 genes (at p < 0.001). In addition to genes previously reported to be induced by type I or type II IFNs, many novel genes were found to be upregulated, including transcription factors, such as ATF3, ATF4, properdin, a key regulator of the complement pathway, a homeobox gene (HESX1), and an RNA editing enzyme (apobec3). Chemokines CXCL10 and CXCL11 were upregulated, whereas CXCL5 was downregulated. Cytokines interleukin-15 (IL-15) and IL-18 were also significantly induced, whereas IL-1alpha and IL-1beta were downregulated. Most other interleukins were not affected. The results of the microarrays were confirmed by kinetic real-time PCR. These data indicate that IFN treatment causes upregulation of genes associated with the stress response, apoptosis, and signaling, and an equal number of genes are downregulated, including those associated with protein synthesis, specific cytokines and chemokines and other biosynthetic functions.

Association of single nucleotide polymorphisms in interferon signaling pathway genes and interferon-stimulated genes with the response to interferon therapy for chronic hepatitis C.

BACKGROUND/AIMS: Interferon signaling pathway genes (IPGs) and interferon-stimulated genes (ISGs) are associated with the host response to hepatitis C virus (HCV) infection. We studied single nucleotide polymorphisms (SNPs) in IPGs and ISGs for their associations with response to pegylated interferon alpha-2a (Peg-IFN-alpha) plus ribavirin therapy in HCV genotype-1 infected patients. METHODS: A two-stage study design was used. First, out of 118 SNPs selected, 91 SNPs from 5 IPGs and 12 ISGs were genotyped in a cohort of 374 treatment-naïve HCV patients and assessed for association with sustained virologic response (SVR). Next, 14 potentially functional SNPs from the OASL gene were studied in this cohort. RESULTS: Three OASL SNPs (rs3213545 and rs1169279 from stage I, and rs2859398 from stage II), were significantly associated with SVR [rs3213545: p=0.03, RR=1.27 (1.03-1.58); rs1169279: p=0.02, RR=1.32 (1.05-1.65) p=0.02; rs2859398: p=0.02, RR=1.29 (1.04-1.61)] after adjusting for other covariates. Further analysis showed that these three SNPs independently associated with SVR. Additionally, a similar trend towards the associations of these three SNPs with SVR was observed in a smaller, independent HCV cohort consisting of subjects from a number of clinical practice settings. CONCLUSIONS: Our study suggests that OASL variants are involved in the host response to IFN-based therapy in HCV patients.

Changes in gene expression during pegylated interferon and ribavirin therapy of chronic hepatitis C virus distinguish responders from nonresponders to antiviral therapy.

Treating chronic hepatitis C virus (HCV) infection using pegylated alpha interferon and ribavirin leads to sustained clearance of virus and clinical improvement in approximately 50% of patients. Response rates are lower among patients with genotype 1 than with genotypes 2 and 3 and among African-American (AA) patients compared to Caucasian (CA) patients. Using DNA microarrays, gene expression was assessed for a group of 33 African-American and 36 Caucasian American patients with chronic HCV genotype 1 infection during the first 28 days of treatment. Results were examined with respect to treatment responses and to race. Patients showed a response to treatment at the gene expression level in RNA isolated from peripheral blood mononuclear cells irrespective of degree of decrease in HCV RNA levels. However, gene expression responses were relatively blunted in patients with poor viral response (<1.5 log(10)-IU/ml decrease at 28 days) compared to those in patients with a marked (>3.5 log(10)-IU/ml decrease) or intermediate (1.5 to 3.5 log(10)-IU/ml decrease) response. The number of genes that were up- or down-regulated by pegylated interferon and ribavirin treatment was fewer in patients with a poor response than in those with an intermediate or marked viral response. However AA patients had a stronger interferon response than CA patients in general. The induced levels of known interferon-stimulated genes such as the 2'5'-oligoadenylate synthetase, MX1, IRF-7, and toll-like receptor TLR-7 genes was lower in poor-response patients than in marked- or intermediate-response patients. Thus, the relative lack of viral response to interferon therapy of hepatitis C virus infection is associated with blunted interferon cell signaling. No specific regulatory gene could be identified as responsible for this global blunting or the racial differences.

Pretreatment sequence diversity differences in the full-length hepatitis C virus open reading frame correlate with early response to therapy.

Pegylated alpha interferon and ribavirin therapy for hepatitis C virus (HCV) genotype 1 infection fails for half of Caucasian American patients (CA) and more often for African Americans (AA). The reasons for these low response rates are unknown. HCV is highly genetically variable, but it is unknown how this variability affects response to therapy. To assess effects of viral diversity on response to therapy, the complete pretreatment genotype 1 HCV open reading frame was sequenced using samples from 94 participants in the Virahep-C study. Sequences from patients with >3.5 log declines in viral RNA levels by day 28 (marked responders) were more variable than those from patients with declines of <1.4 log (poor responders) in NS3 and NS5A for genotype 1a and in core and NS3 for genotype 1b. These correlations remained when all T-cell epitopes were excluded, indicating that these differences were not due to differential immune selection. When the sequences were compared by race of the patients, higher diversity in CA patients was found in E2 and NS2 but only for genotype 1b. Core, NS3, and NS5A can block the action of alpha interferon in vitro; hence, these genetic patterns are consistent with multiple amino acid variations independently impairing the function of HCV proteins that counteract interferon responses in humans, resulting in HCV strains with variable sensitivity to therapy. No evidence was found for novel HCV strains in the AA population, implying that AA patients may be infected with a higher proportion of the same resistant strains that are found in CA patients.