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Mediators of Inflammation
Volume 2016, Article ID 6986175, 17 pages
Research Article

Exploring New Inflammatory Biomarkers and Pathways during LPS-Induced M1 Polarization

1Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal
2Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal

Received 9 May 2016; Revised 18 October 2016; Accepted 7 November 2016

Academic Editor: Soh Yamazaki

Copyright © 2016 Carolina Cunha et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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.