ArrayExpress Uploader0human3063arrayexpress_sid4In response to inflammatory stimulation, dendritic cells (DCs) have a remarkable pattern of differentiation (maturation) that exhibits...19193853E-GEOD-13296/profile/8773/arrayexpressuploader04cytokinedendriticinterleukininterleukin-1monocyteDec.12, 2014Falsemir-155-ko-in-human-dendritic-cellsE-GEOD-13296_A-AFFY-44miR-155 KO in human dendritic cellsSep.10, 2014In response to inflammatory stimulation, dendritic cells (DCs) have a remarkable pattern of differentiation (maturation) that exhibits specific mechanisms to control immunity. Here, we show that in response to Lipopolysaccharides (LPS), several microRNAs (miRNAs) are regulated in human monocyte-derived dendritic cells. Among these miRNAs, miR-155 is highly up-regulated during maturation. Using LNA silencing combined to microarray technology, we have identified the Toll-like receptor / interleukin-1 (TLR/IL-1) inflammatory pathway as a general target of miR-155. We further demonstrate that miR-155 directly controls the level of important signal transduction molecules. Our observations suggest, therefore, that in mature human DCs, miR-155 is part of a negative feedback loop, which down-modulates inflammatory cytokine production in response to microbial stimuli. We devised a strategy to functionally inhibit the mature form of miR-155 with the aim of identifying the signaling pathways controlled by miR-155 during DC maturation. A LNA-modified oligonucleotide, specifically designed for miR-155 knockdown (anti-miR-155 LNA) was introduced in moDCs by nucleofection prior LPS stimulation. 24h after transfection, a reduction in miR-155 levels of 8- and 32-fold was observed by qPCR in immature and mature moDCs respectively. A comparative microarray analysis (Affymetrix U133 2.0 chip) was performed among miR-155 silenced (anti-miR-155 LNA) and control transfected (scramble LNA) moDCs, exposed or not to LPS. Thus, four samples were totally analyzed. As expected from the limited expression of miR-155 in non-activated DCs, little variation in mRNA expression (177 probe sets differentially expressed employing a cut-off of 1.5) was detected upon miR-155 silencing. Conversely, in LPS-activated cells many mRNAs (1324 probe sets, 770 up-regulated and 554 down-regulated) were affected by miR-155 inhibition.http://www.ebi.ac.uk/arrayexpress/experiments/E-GEOD-13296http://www.ebi.ac.uk/arrayexpress/experiments/E-GEOD-13296/samples/