Human immunodeficiency virus and hepatitis C infections induce distinct immunologic imprints in peripheral mononuclear cells

Abstract

Coinfection with hepatitis C virus (HCV) is present in one-third of all human immunodeficiency virus (HIV)-infected individuals in the United States and is associated with rapid progression of liver fibrosis and poor response to pegylated interferon (IFN) and ribavirin. In this study we examined gene expression profiles in peripheral blood mononuclear cells (PBMCs) from different groups of individuals who are monoinfected or coinfected with HIV and HCV. Data showed that HIV and HCV viremia up-regulate genes associated with immune activation and immunoregulatory pathways. HCV viremia is also associated with abnormalities in all peripheral immune cells, suggesting a global effect of HCV on the immune system. Interferon-alpha-induced genes were expressed at a higher level in PBMCs from HIV-infected individuals. HCV and HIV infections leave distinct profiles or gene expression of immune activation in PBMCs. HIV viremia induces an immune activated state; by comparison, HCV infection induces immunoregulatory and proinflammatory pathways that may contribute to progression of liver fibrosis.

Conclusion: An aberrant type-I IFN response seen exclusively in HIV-infected individuals could be responsible for the poor therapeutic response experienced by HIV/HCV coinfected individuals receiving interferon-alpha-based current standard of care.

Conflict of interest statement

Conflict of Interest Statement

None of the other authors have any conflicts of interest to report.

Figures

Figure 1. Clustering of differentially expressed genes in PBMCs from 5 groups (See Methods section)

Levels of gene expression were assayed using Affymetrix Human Genome U133A chips. A total of 1,813 differentially expressed genes were identified. Genes were grouped using K-means clustering, and samples were grouped by hierarchical clustering. Differences in relative levels of gene expression (Z-score) are indicated in color, where red indicates up-regulation and green indicates down-regulation relative to that of corresponding gene expression in controls. The numbers in parentheses indicate the number of genes in each cluster. Some genes are listed twice because certain probes recognize multiple regions of a single gene. Cluster 1 consists of genes down-regulated both in group B and C individuals. Cluster 2 consists of genes up-regulated in groups B and D individuals. Cluster 3 consists of genes up-regulated in group C and E. Cluster 4 consists of genes up-regulated only in group C individuals. Cluster 5 consists of genes down-regulated only in group B individuals. Cluster 6 consists of genes up-regulated only in group B individuals. Select biologically relevant genes of Clusters 2, 5 and 6 are shown on the right.

Figure 2. Validation of DNA microarray data by bDNA analysis

DNA microarray expression of IFIG genes was validated using a customized bDNA assay. The expression of two representative IFIGs by DNA microarray (left) and bDNA assay (right) for the two gene candidates OAS1 (A,B) and MX1 (C,D) indicate that HIV-infected individuals have a higher level of IFIG expression overall than the other groups of individuals. Fold change of gene expression is calculated as the change within a group compared to that observed in normal volunteers. The expression of both OAS1 and MX1 were significantly different between Group C and others by microarray (p

Figure 3. Average differential gene expression profiles of the five groups of individuals

Using either flow cytometry (surface expression) or ELISA (secreted proteins) selected genes were validated based on their biological relevance (following literature-mining algorithms). Clusters 2, 5 and 6 were selected based on the identification of cell surface receptors and secreted proteins most relevant to HCV infection status.

Figure 4. HCV Infection has a Global Effect on Immune Cells

A. The percentage of CD10+ immature B cells in the peripheral blood measured by flow cytometry from 5 individuals in the HCV mono-infected group was significantly higher than that of the other 4 groups (p<0.03). B. The percentage of NKp30+ cells among NK cells in the peripheral blood was measured by flow cytometry from the 5 groups. HCV-infected (both mono and HIV co-infected) individuals had a significantly higher percentage of NKp30+ NK cells than that of the other groups (p<0.04). C. The percentage of CD80+ cells among CD3- in HCV mono-infected individuals was significantly higher than that of the other 4 groups (p<0.03).

Figure 5. Chronic HCV Infection is Associated with Markers of Liver Injury

A. The levels of CX3CL1 present in the supernatants of PBMCs from the 5 groups were determined by ELISA. PBMCs from HCV mono-infected individuals secreted significantly higher levels of CX3CL1 than did the other 4 groups (p<0.02). B. Mean Fluorescent Intensity (MFI) of IGF-1R expression on PBMCs showed that HCV-infected (both mono and HIV co-infected) individuals had significantly higher expression of IGF-1R than did the other 3 groups (p<0.02).

Figure 6. Chronic HCV infection is associated with increased levels of pro-inflammatory chemokines

A. The levels of CCL-7 (Monocyte Chemotactic Protein -3) present in the supernatants of PBMCs from the 5 groups were quantified by ELISA. PBMCs from HCV mono-infected individuals secreted significantly higher levels of CCL-7 than did the other 4 groups (p

Figure 7. HIV-infection results in increased expression of IFIG that is not seen in normal individuals and HCV-infected individuals

The gene expression profile of several differentially regulated genes was measured using a customized bDNA assay. IFIG genes were found to be up-regulated in HIV viremic individuals compared to other groups of individuals. (p