167/2011 and 109/2012). T cells are activated by R-1479 splenic DCs in the presence of their cognate peptide. Indeed, prior exposure of DCs to OxPAPC inhibited their subsequent ability to drive the generation of interferon-gamma (IFN-)-producing Th1 T cells and instead promoted the generation of IL-4-producing Th2 T?cells, whereas DPPC treatment showed no comparable effect (Fig?(Fig1G1G and ?andH).H). OxPAPC treatment not only reduced the frequency of T cells producing IFN-, but also diminished the absolute amount of T-cell-secreted IFN- protein (Fig?(Fig1I).1I). Altogether, these findings demonstrated a strong anti-inflammatory bioactivity of OxPAPC and suggested that OxPL may influence both innate and adaptive immune responses generated OxPAPC preparations represent complex mixtures of OxPL species with distinct bioactivities Both pro- and anti-inflammatory activities of OxPAPC have been reported (Berliner & Watson, 2005; Bochkov generated OxPAPC preparations represent complex mixtures of OxPL species with distinct bioactivities Mass spectrometric quantification of a variety of OxPL species obtained by CuSO4-catalyzed oxidation of PAPC for 2 and 24?h. Mean??SEM of duplicate determinations are shown. Correlation between R-1479 the abundance of individual OxPL species detected in mixtures of differentially oxidized OxPL preparations and the capacity of the respective overall OxPL mixtures to suppress the IL-12 secretion of thioglycollate-elicited macrophages. Dots represent data of individual OxPAPC preparations. An OxPL containing a fatty acid epoxycyclopentenone mediates the anti-inflammatory bioactivity of OxPAPC To unambiguously identify the relevant OxPL species, we next tested the bioactivity of each of these candidate lipids in isolated form using synthetic compounds. We focused our analysis on OxPL that was either commercially available or synthesized by MMP14 us according to recently established routes (Egger co-culture system (Fig?(Fig3F).3F). As could have been anticipated from above observations, EC and 15d-PGJ2 as well as their respective OxPL, PECPC, and 15d-PGJ2PC efficiently limited Th1-cell polarization, whereas POVPC, PGPC, and KOdiAPC had no such effect (Fig?(Fig3F)3F) consistent with the inability to inhibit IL-12 production (Fig?(Fig3A3A and ?andC).C). Collectively, these data identified EC as the most potent anti-inflammatory OxPAPC component and implicated the molecular pathways that are physiologically targeted by 15d-PGJ2 as potential mechanism for this activity. Open in a separate window Figure 3 An OxPL containing a fatty acid epoxycyclopentenone mediates the anti-inflammatory bioactivity of OxPAPC Selected candidate lipids were tested for their inhibitory activity on R837-induced (5?g/ml; 18?h) cytokine secretion in BMDCs. Concentrations of indicated lipids: PECPC (10?M), PEIPC (10?M), OxPAPC (40?g/ml), DPPC (40?g/ml), POVPC (40?M), PGPC (40?M), and KOdiAPC (40?M). Representative data (mean??SD of triplicate determinations) from one of three independent experiments are shown. ****(Supplementary Fig S4). Instead, the extent of cellular adhesion observed in the lung vasculature of EC-treated animals rather resembled that of na?ve R-1479 controls not treated with LPS (Fig?(Fig5A).5A). This potent effect of EC was illustrated by a quantitative morphometric analysis confirming that EC pretreatment significantly reduced the number of adherent cells per defined vessel length (Fig?(Fig5B5B and ?andC).C). Prior i.t. administration of EC also efficiently interfered with leukocyte migration into the lung upon i.p. LPS challenge. In particular, EC-treated animals exhibited significantly smaller total infiltrates and reduced absolute neutrophil numbers in their lungs (Fig?(Fig5D5D and R-1479 ?andE)E) as compared to DPPC-treated controls. Complementing our findings, EC also strongly decreased the LPS-induced secretion of the pro-inflammatory cytokines IL-6 (Fig?(Fig5F)5F) and IL-12 (Fig?(Fig5G)5G) and protected mice from sepsis-associated vascular and pulmonary inflammation. Open in a separate window Figure 5 EC mitigates sepsis-associated inflammation observations encouraged us to further investigate the structureCactivity relationship of EC in order to elucidate key structural determinants mediating its potent bioactivity. We hypothesized a potential involvement of the epoxide group as well as the endocyclic and exocyclic enones and therefore evaluated the bioactivity of synthetic EC variants that selectively lacked these electrophilic sites (Fig?(Fig6A6A and ?andB).B). Our results revealed the cyclopentenone double bond as main driver of the overall bioactivity, since its removal in variant MonoRed A completely abolished the anti-inflammatory property of EC. This notion was further supported by the fact that introduction of another electrophilic group, an epoxide, at this position into MonoRed A, which led to the variant Bisepoxide, restored its bioactivity. In addition, also the epoxide group and the extra-cyclic double bond R-1479 in ,.