Genome-wide expression analysis demonstrates a dominant role of TLR4 for activation of human phagocytes by the alarmin MRP8

ABSTRACT: The alarmins myeloid-related protein (MRP) 8 and MRP14 are the dominant cytoplasmic proteins in phagocytes. After release by activated phagocytes extracellular MRP8/MRP14 complexes promote inflammation in many diseases, including infections, allergies, autoimmune diseases, rheumatoid arthritis or inflammatory bowel disease. As receptors for the pro-inflammatory effects of human MRP8, the active component of the MRP8/MRP14-complex, Toll-like receptor (TLR) 4 and the multi-ligand receptor of advanced glycation end products (RAGE) are controversial discussed. Using a comparative bioinformatics analysis between genome-wide response patterns of monocytes to MRP8, endotoxin and different cytokines we demonstrated a dominant role of TLR4 during MRP8-mediated phagocyte activation. The relevance of this signaling pathway could be confirmed in independent cell models for TLR4 and RAGE dependent signaling in mouse and man. In addition to well-known proinflammatory functions of MRP8 our systems biology approach unraveled a novel anti-apoptotic effect of MRP8 on monocytes which was confirmed in independent functional experiments. Our data define the dominance of the TLR4-MRP8 axis in activation of human phagocytes which represents a novel attractive target for modulation of overwhelming innate immune responses. We used microarrays to detail the global programme of gene expression underlying cellularisation and identified distinct classes of up-regulated genes during this process. Human blood monocyte stimulated with various stimuli (control, MRP8, LPS, TNF, IL1) were selected for RNA extraction and hybridization on Affymetrix microarrays.

ORGANISM(S): Homo sapiens

SUBMITTER: Joachim Schultze 

PROVIDER: E-GEOD-56681 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress