Gene expression profiling defines ATP as a key regulator of human dendritic cell functions

Extracellular ATP and PGE2 are two cAMP-elevating agents inducing semi-maturation of human monocyte-derived dendritic cells (MoDCs). We have extensively compared the gene expression profiles induced by ATPγS and PGE2 in human MoDCs using microarray technology. At 6 h of stimulation, ATPγS initiated an impressive expression profile compared to that of PGE2 (1125 genes compared to 133 genes respectively) but after 24 h, the number of genes regulated by ATPγS or PGE2 was more comparable. Many target genes involved in inflammation have been identified and validated by quantitative RT-PCR experiments. We have then focused on novel ATPγS and PGE2 target genes in MoDCs including colony-stimulating factor-1 (CSF-1), MCP-4/CCL13 chemokine, vascular endothelial growth factor (VEGF-A) and neuropilin-1 (NRP-1). ATPγS strongly down-regulated CSF-1 receptor mRNA and CSF-1 secretion which are involved in monocyte and DC differentiation. Additionally, ATPγS down-regulated several chemokines involved in monocyte and DC migration including CCL2/MCP-1, CCL3/MIP-1alpha, CCL4/MIP-1beta, CCL8/MCP-2 and CCL13/MCP-4. Interestingly, VEGF-A – a major angiogenic factor displaying immunosuppressive properties - was secreted by MoDCs in response to ATPγS, ATP or PGE2, alone or in synergy with LPS. Finally flow cytometry experiments have demonstrated that ATPγS, ATP and PGE2 down-regulate NRP-1, a receptor playing inter alia an important role in the activation of T lymphocytes by DCs. Our data give an extensive overview of the genes regulated by ATPγS and PGE2 in MoDCs and an important insight into the therapeutic potential of ATP- and PGE2-treated human DCs. Keywords: Time course, treatment comparison Immature DCs (106 cells/mL) were stimulated by ATPγS (100 µM) or PGE2 (500 nM) for 2, 6, 12 or 24 h in the complete RPMI medium. Labeled RNA were hybridized to HEEBO arrays containing on average 44544 human 70mer oligonucleotides (Stanford University, US). The data were obtained from two independent donors.