The Paradigm of Macrophage Polarization is not Applicable per seto Human Circulating Monocytes

ABSTRACT: Macrophage activation is required for the control of innate and adaptive immune responses. The classification in M1 and M2 macrophages based on a combination of small numbers of membrane and soluble markers is operational in murine and human macrophages. If this classification may be extended to circulating monocytes is not elucidated. To answer such question, human monocytes were stimulated for 6 and 18 hours with IFN-gamma and IL-4, two canonical agonists of M1/M2 polarization in macrophages, and gene expression programs were investigated with whole genome microarrays. The temporal analysis of these programs showed marked differences to both IFN-gamma and IL-4. In 6-h stimulated monocytes, gene categories related to inflammatory and immune responses were enriched, and these monocytes exhibited a M1 and M2 polarization in response to IFN-gamma and IL-4, respectively, as found in macrophages. In 18-h stimulated monocytes, the categories related to innate immunity and metabolic pathways were enriched in response to IFN-gamma and IL-4, whereas PPAR signaling pathway was specifically enriched in response to IL-4. In addition, the M1 and M2 polarization induced by IFN-gamma and IL-4, respectively, was replaced by an original transcriptional program that did not depend on IFN-gamma and IL-4. This program appeared as networks around chemokines, NF-kappaB/MAP kinase pathways and MHC class II molecules. These results clearly demonstrated that monocyte activation consisted of an early polarized stage likely involved in effector responses and a delayed stage that may regulate host responses. The establishment of databases on human circulating monocytes using high throughput methods may be critical for pathophysiological and clinical non-invasive studies. Peripheral blood mononuclear cells (PBMCs) were isolated from leukopacks from normal blood donor buffy coats (Etablissement Français du Sang, Marseille, France) by Ficoll density gradient

ORGANISM(S): Homo sapiens

SUBMITTER: adil ef 

PROVIDER: E-GEOD-27658 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress