Human plasma extracellular vesicles impair inflammatory responses to a viral pamp in M-CSF but not GM-CSF monocyte- derived macrophages

ADAMCZYK ALAN; LEICAJ M LUZ; FABIANO MARTINA; OSTROWSKI MATÍAS; PÉREZ PAULA S

Congreso; SAIC.SAI.AAFE.NANOMED.AR 2021; 2021

Extracellular vesicles are heterogeneous membrane structures, which can modulate normal and pathological conditions. The aim of this work was to study the role of healthy donors’ plasma EVs (pEVs) in the modulation of the inflammatory response elicited by a viral PAMP in monocyte derived macrophages with either inflammatory (GM-MDMs) or resolution (M-MDMs) profiles. pEVs were isolated from plasma samples by size exclusion chromatography, followed by centrifugation. Human monocytes were isolated from healthy donors’ buffy coats via density gradient centrifugation followed by positive isolation with CD14 magnetic beads, and differentiated with M-CSF or GM-CSF for 7 days. Macrophages were stimulated with the TLR 7/8 agonist resiquimod (RSQ) for 24 h in the presence or absence of pEVs. The production of cytokines in cell culture supernatants was evaluated by cytokine bead array and ELISA. Characterization and purity of EVs were assessed by western blotting. Several signaling pathways were studied by phosphoarray and western blot assays.EV-treatment of M-MDM exposed to RSQ significantly reduced the secretion of IL-6 and TNF and increased the secretion of IL-10, as compared to only RSQ treated cells. In contrast, GM-MDMs co-stimulated with RSQ and EVs presented an increased IL6 response while no changes were observed in TNF or IL10 secretion. Signaling analyses further performed on M-MDMs indicated that EV-treatment reduced phosphorylation of activation pathways, such as MAPK and AKT.pEVs appear to have an homeostatic role on M-MDMs exposed to a viral PAMP by reducing their inflammatory response. In contrast, pEVs are not able to modulate pro- inflammatory GM-MDMs. Further studies are needed to identify the cargo molecules responsible for these effects. Understanding in-vivo implications of these findings may lead to new therapies development for chronic inflammation.