IMEX   05356
INSTITUTO DE MEDICINA EXPERIMENTAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Platelets promote monocyte polarization to a M1 phenotype upon LPS stimulation
Autor/es:
MENA HA; CARESTIA A; CARRERA SILVA EA; SCHATTNER M; NEGROTTO S
Lugar:
Berlin
Reunión:
Congreso; ISTH Congress; 2017
Institución organizadora:
ISTH
Resumen:
Platelets and monocyte/macrophages interaction appears to play a relevant role in the pathophysiology of sepsis. However, it has been reported that platelets can positively or negatively regulate monocytes/macrophages responses. Although the reasons for these discrepancies are not clear, LPS concentration seems to be a critical determinant. To clarify the role of platelets in the biology of monocytes/macrophages upon LPS challenge, we explored monocyte/macrophage functions in co-cultures with platelets in presence of a broad range of LPS concentrations.Human monocytes were purified by positive selection, incubated with autologous platelets and stimulated with LPS for 1-5 days. LPS induced the release of pro (TNF/IL-6)- and anti (IL-10/IL-4)-inflammatory cytokines (ELISA) in a LPS concentration-dependent manner at 24 and 48 hs, respectively. The co-incubation with platelets decreased the amount of all cytokines at all LPS concentrations (Fig.1). While low LPS concentrations (01-10pg/ml) differentiated monocytes into M2 macrophages by decreasing CD64 and augmenting CD206 and CD163 (flow cytometry), a more pro-inflammatory phenotype was observed with increasing LPS concentrations (Fig.2). The presence of platelets polarized monocytes predominantly towards M1 phenotype at all LPS concentrations. Accordingly, macrophages generated in the platelet/monocytes co-culture experiments had an increase capacity to produce TNF and exerted a higher bacterial phagocytic activity (flow cytometry). Moreover, endothelial cells presented a reduced capability of healing when they were incubated with supernatants from platelet/monocytes co-culture-derived macrophages (scratch assay) (Fig.2). In a transwell culture system, the effect of platelets on monocyte polarization was not observed.In conclusion, upon LPS stimulation, platelets decrease the release of both pro and anti-inflammatory cytokines from monocytes and polarize them to M1 macrophages in a cell-contact dependent manner.