Chronic CD4 + T-Cell Activation and Depletion in Human Immunodeficiency Virus Type 1 Infection: Type I Interferon-Mediated Disruption of T-Cell Dynamics

Abstract

ABSTRACT The mechanism of CD4 + T-cell depletion during chronic human immunodeficiency virus type 1 (HIV-1) infection remains unknown. Many studies suggest a significant role for chronic CD4 + T-cell activation. We assumed that the pathogenic process of excessive CD4 + T-cell activation would be reflected in the transcriptional profiles of activated CD4 + T cells. Here we demonstrate that the transcriptional programs of in vivo-activated CD4 + T cells from untreated HIV-positive (HIV + ) individuals are clearly different from those of activated CD4 + T cells from HIV-negative (HIV − ) individuals. We observed a dramatic up-regulation of cell cycle-associated and interferon-stimulated transcripts in activated CD4 + T cells of untreated HIV + individuals. Furthermore, we find an enrichment of proliferative and type I interferon-responsive transcription factor binding sites in the promoters of genes that are differentially expressed in activated CD4 + T cells of untreated HIV + individuals compared to those of HIV − individuals. We confirm these findings by examination of in vivo-activated CD4 + T cells. Taken together, these results suggest that activated CD4 + T cells from untreated HIV + individuals are in a hyperproliferative state that is modulated by type I interferons. From these results, we propose a new model for CD4 + T-cell depletion during chronic HIV-1 infection.