Exploring New Inflammatory Biomarkers and Pathways during LPS-Induced M1 Polarization
Open Access
- 21 December 2016
- journal article
- research article
- Published by Hindawi Limited in Mediators of Inflammation
- Vol. 2016, 1-17
- https://doi.org/10.1155/2016/6986175
Abstract
Identification of mediators triggering microglia activation and transference of noncoding microRNA (miRNA) into exosomes are critical to dissect the mechanisms underlying neurodegeneration. We used lipopolysaccharide- (LPS-) induced N9 microglia activation to explore new biomarkers/signaling pathways and to identify inflammatory miRNA (inflamma-miR) in cells and their derived exosomes. Upregulation of iNOS and MHC-II (M1-markers) and downregulation of arginase 1, FIZZ1 (M2-markers), and CX3CR1 (M0/M2 polarization) confirmed the switch of N9 LPS-treated cells into the M1 phenotype, as described for macrophages/microglia. Cells showed increased proliferation, activated TLR4/TLR2/NF-κB pathway, and enhanced phagocytosis, further corroborated by upregulated MFG-E8. We found NLRP3-inflammasome activation in these cells, probably accounting for the increased extracellular content of the cytokine HMGB1 and of the MMP-9 we have observed. We demonstrate for the first time that the inflamma-miR profiling (upregulated miR-155 and miR-146a plus downregulated miR-124) in M1 polarized N9 cells, noticed by others in activated macrophages/microglia, was replicated in their derived exosomes, likely regulating the inflammatory response of recipient cells and dissemination processes. Data show that LPS-treated N9 cells behave like M1 polarized microglia/macrophages, while providing new targets for drug discovery. In particular, the study yields novel insights into the exosomal circulating miRNA during neuroinflammation important for emerging therapeutic approaches targeting microglia activation.Keywords
Funding Information
- Fundação para a Ciência e a Tecnologia (PTDC/SAU-FAR/118787/2010, UID/DTP/04138/2013, SFRH/BPD/76590/2011, SFRH/BD/91316/2012, SFRH/BD/102718/2014)
This publication has 91 references indexed in Scilit:
- Characterization of phenotype markers and neuronotoxic potential of polarised primary microglia in vitroBrain, Behavior, and Immunity, 2013
- The microglial activation state regulates migration and roles of matrix-dissolving enzymes for invasionJournal of Neuroinflammation, 2013
- Involvement of MicroRNA in Microglia-Mediated Immune ResponseJournal of Immunology Research, 2013
- Outbred ICR/CD1 mice display more severe neuroinflammation mediated by microglial TLR4/CD14 activation than inbred C57Bl/6 miceNeuroscience, 2011
- MicroRNA-124 promotes microglia quiescence and suppresses EAE by deactivating macrophages via the C/EBP-α–PU.1 pathwayNature Medicine, 2010
- The Role of Microglia in Synaptic Stripping and Synaptic Degeneration: A Revised PerspectiveASN Neuro, 2010
- Adenosine A2A receptor mediates microglial process retractionNature Neuroscience, 2009
- The NALP3 inflammasome is involved in the innate immune response to amyloid-βNature Immunology, 2008
- NF-κB-dependent induction of microRNA miR-146, an inhibitor targeted to signaling proteins of innate immune responsesProceedings of the National Academy of Sciences of the United States of America, 2006
- Identification of a factor that links apoptotic cells to phagocytesNature, 2002