Chiral lipidomics of E-series resolvins: aspirin and the biosynthesis of novel mediators.

Control of the inflammatory response is of wide interest given its important role in many diseases. In recent years we identified novel mechanisms and lipid mediators that play an active role in stimulating the resolution of self-limited acute inflammation. These novel pro-resolving mediators include the essential fatty acid-derived lipoxins, resolvins, protectins and maresins. Members of each possess a unique pro-resolving mechanism of action; each limits neutrophilic infiltration, regulates local mediators (chemokines, cytokines) as well as stimulates macrophage-enhanced clearance of apoptotic PMN, cellular debris and microbes. Given this unique mechanism of action, resolvins have already been shown to play pivotal roles in regulating key events in a wide range of experimental inflammatory diseases. These pro-resolving mediators also provide a molecular link between omega-3 essential fatty acids (e.g. EPA, DHA) and the resolution process of inflammation and tissue homeostasis. Here, we review recent evidence obtained using chiral LC-MS-MS-based lipidomics to identify a novel 18S-series of resolvins derived from EPA. Resolvin E1 possesses potent actions in vivo and in vitro demonstrated now in many laboratories, and herein we review comparisons in E-series resolvin biosynthesis and action of 18S-resolvin E1 and 18S-resolvin E2. The biosynthesis and formation of both 18S and 18R-series are enhanced with aspirin treatment and involve the utilization of dietary EPA as well as recombinant human 5-lipoxygenase and LTA(4) hydrolase in their stereospecific biosynthesis. Herein we also demonstrate the utility of LC-MS-MS-based lipidomics in identifying resolvins, protectins and related products in marine organisms such as Engraulis (Peruvian anchovy). These new findings emphasize the utility of chiral LC-MS-MS lipidomics and the potential for identifying new resolution circuits with chiral LC-MS-MS-based lipidomics and metabolomics.