Circulating Monocytes in HIV-1 infected Viremic Subjects Exhibit an Anti-Apoptotic Gene Signature

Mechanisms that may allow circulating monocytes to persist as CD4 T cells diminish in HIV-1 infection have not been investigated. We have characterized steady-state gene expression signatures in circulating monocytes from HIV-infected subjects and have identified a stable anti-apoptosis gene signature comprised of 38 genes associated with p53, CD40L, TNF and MAPKinase signaling networks. The significance of this gene signature is indicated by our demonstration of cadmium chloride- or Fas ligand-induced apoptosis resistance in circulating monocytes in contrast to increasing apoptosis in CD4 T cells from the same infected subjects. As potential mechanisms in vivo, we show that monocyte CCR5 binding by HIV-1 virus or agonist chemokines serve as independent viral and host modulators resulting in increased monocyte apoptosis resistance in vitro. We also show evidence for concordance between circulating monocyte apoptosis-related gene expression in HIV-1 infection in vivo and available datasets following viral infection or envelope exposure in monocyte derived macrophages in vitro. The identification of in vivo gene expression associated with monocyte resistance to apoptosis is of relevance to AIDS pathogenesis since it would contribute to: (1) maintaining viability of infection targets and long-term reservoirs of HIV-1 infection in the monocyte/macrophage populations, and (2) protecting a cell subset critical to host survival in spite of sustained high viral replication. Keywords: two group study design 33 samples hybridized, including 13 HIV-1 Patients, 12 Healthy Controls and 4 HIV-1 Patients and 4 Controls followed 6 months later