Comparative microarray analysis revealed an additional set of genes that were significantly upregulated in E10.5 TLR2+ CD11b+ macrophages. This analysis, together with our genetic, microscopic, and

biochemical evidence, showed that embryonic phagocytes express protein machinery that is essential for the recycling of cellular iron and that this expression can be regulated by TLR engagement in a MyD88-dependent manner, leading to typical inflammatory M1 responses. These results characterize NVP-BEZ235 the utility of TLRs as suitable markers for early embryonic phagocytes as well as molecular triggers of cellular responses, the latter being demonstrated by the involvement of TLRs in an inflammation-mediated regulation of embryonic homeostasis via iron metabolism. “
“Synthetic oligonucleotides

(ODN) expressing CpG motifs mimic the ability of bacterial DNA to trigger the innate immune system via TLR9. Plasmacytoid dendritic cells (pDCs) make a critical contribution to the ensuing immune response. This work examines the induction XL765 of antiviral (IFN-β) and pro-inflammatory (IL-6) cytokines by CpG-stimulated human pDCs and the human CAL-1 pDC cell line. Results show that interferon regulatory factor-5 (IRF-5) and NF-κB p50 are key co-regulators of IFN-β and IL-6 expression following TLR9-mediated activation of human pDCs. The nuclear accumulation of IRF-1 was also observed, but this was a late event that was dependant on type 1 IFN and unrelated to the initiation of gene expression. IRF-8 was identified as a novel negative regulator of gene activation in CpG-stimulated pDCs. As variants of IRF-5 and IRF-8 were recently found to correlate with susceptibility to certain autoimmune diseases, these findings are relevant to our understanding of the pharmacologic effects of “K” ODN and the role of TLR9 ligation under physiologic,

pathologic, and therapeutic conditions. Cells of the immune system utilize TLR to sense ligands uniquely expressed by pathogenic microorganisms. Human plasmacytoid dendritic cells (pDCs) use TLR9 to detect Resminostat the unmethylated CpG motifs present at high frequency in bacterial DNA [1-3]. Synthetic oligonucleotides (ODN) encoding unmethylated CpG motifs mimic the effect of bacterial DNA and trigger pDC activation. Several structurally distinct classes of CpG ODN have been described. Those of the “K” class (also referred to as “B” class) are characterized by their ability to stimulate human pDCs to secrete pro-inflammatory cytokines such as IL-6 and TNF-α. Clinical trials of “K” ODN show promise for the treatment of cancer, allergy, and infectious disease [4, 5]. Identifying the signaling pathways triggered when human pDCs are stimulated by “K” ODN is, thus, of clinical relevance. pDCs are a major source of type I IFNs and various pro-inflammatory cytokines [6, 7].