PhD Scientific Days 2024

Molecular Medicine III.

Neutrophil-derived extracellular vesicles regulate the viability of monocytes and modulate the inflammatory response of monocytes and macrophages

Text of the abstract

Introduction
Extracellular vesicles (EVs) are released by every known cell type and their ability to transfer bioactive molecules to recipient cells make them crucial mediators of intercellular communication. Our laboratory formerly characterized three different types of neutrophil- derived (PMN) extracellular vesicles (EV): released spontaneously (spEV), generated upon opsonized zymosan treatment (oZ-EV), and produced by apoptotic cells (apoEV). Our previous experiments showed that these PMN-EVs exert either anti- or proinflammatory effect on neutrophils themselves and endothelial cells but there is no data about their effects on other leukocytes.
Aims
We investigated the effect of PMN-EVs on the viability and the effector functions of monocytes and the possible underlying integrin effect. The impact of PMN-EVs on monocyte-macrophage differentiation and migration ability was also examined.
Methods
Neutrophils and monocytes were isolated from human blood, macrophages were differentiated via M-CSF. Spontaneously (spEV), upon opsonized particle stimulation (oZ-EV) and during apoptosis (apoEV) generated EVs were isolated by two-step centrifugation and filtration. EVs effect on viability was observed by flow cytometry (FC) and LDH cytotoxicity assay. Monocytes ROS production was monitored by lucigenin assay, cytokine production was measured by ELISA and CD11b expression were determined by FC. The macrophage differentiation was investigated by FC and fluorescent microscopy, the migration was measured by scratch assay.
Results
Monocytes viability was significantly increased by apoEV. SpEV significantly delayed monocytes’ ROS production and significantly decreased the CD11b expression of monocytes. LPS-induced IL-8 production was significantly reduced by spEV, IL-1RA by apoEV. SpEV and apoEV significantly increased the number of differentiated macrophages and apoEV treatment resulted in an increase in migration capacity.
Conclusions
Neutrophils are key players in inflammatory processes. Pro-inflammatory PMN-EVs regulate processes in the early phase of inflammation. During resolution phase, PMNs interact with monocytes and macrophages to promote tissue homeostasis by releasing anti-inflammatory EVs.
Funding
EFOP-3.6.3-VEKOP-16-2017-00009
NKFIH FK137770
TKP2021-EGA-24
János Bolyai Research Scholarship of the Hungarian Academy of Sciences