Fig. 4

M2-Exos lead to lipid mediator class switching of PMNs during sepsis. a, c and d PMNs isolated from healthy volunteers were preactivated upon adding 20% septic plasma (SP) to the culture medium, and 20% plasma from healthy volunteers (HP) was used as a negative control. After 1 h, the culture medium was replaced with fresh medium, and PMNs were then cocultured with PBS/M0-Exos/M2-Exos (100 μg/mL) derived from PBMC-differentiated macrophages for 5 h. b, e and f PMNs from septic patients were directly cocultured with M0/M2-Exos (100 μg/mL) for 5 h after isolation. a and b Targeted metabolite analysis of eicosanoids in M0/M2-Exo-treated PMNs using liquid chromatography high-resolution mass spectrometry. LXA4 (c and e) and LTB4 (d and f) concentrations in the supernatant of cocultured PMNs were detected by ELISA kits. g LTB4 levels were compared in M0-Exos and M2-Exos from PBMC-differentiated macrophages by ELISA. One-way analysis of variance with Tukey’s multiple comparisons test (c–f) or Student’s t test (a, b, g) was used for the analysis. Graphs represent means ± standard deviations, n = 3–5; *P < 0.05, **P < 0.01 compared within two groups. TXB2, thromboxane B2; PGE2, prostaglandin E2; PGD2, prostaglandin D2; PGA2, prostaglandin A2; PGJ2, prostaglandin J2; 6-trans-LTB4,6-trans leukotriene B4; 15-HETE, 15-hydroxyeicosatetraenoic acid; 14,15-EET, 14,15-epoxy-5,8,11-eicosatrienoic acid; 5-oxo-ETE, 5-Oxo-6,8,11,14-eicosatetraenoic acid; 11,12-EET, 11,12-epoxy-5,8,14-eicosatrienoic acid; 8,9-EET, 8,9-epoxyeicosatrienoic acid