Deciphering the role of n-3 polyunsaturated fatty acid-derived lipid mediators in health and disease.

Accumulating evidence indicates that, analogous to n-6 PUFA, n-3 PUFA are enzymatically converted into diverse families of bioactive mediators that play numerous roles in physiology. These mediators, which include the resolvins, protectins and maresins, are particularly important in resolving acute inflammation and also appear to play a role in enhancing host defence. Given the protective actions of n-3 PUFA in human subjects and in animal models of disease, active generation of bioactive mediators may in part underlie these protective effects. Several studies have demonstrated that bioactive autacoids generated from n-3 PUFA have direct anti-inflammatory and pro-resolution actions, and the structures of many of these endogenous mediators have been elucidated. The diverse roles of these lipid mediators in health and disease, regulation of their biosynthesis, as well as identification of specific receptors and cellular targets, are emerging. This brief review will highlight the biosynthesis of resolvins, protectins and maresins, and discuss their receptor-mediated biological actions in promoting the resolution of inflammation. Their potential use as a new class of pro-resolution therapeutics, as well as gaps in knowledge and challenges for future research, will also be discussed. Overall, the identification of these novel families of lipid mediators has yielded insight into the protective actions of n-3 PUFA and may lead to the development of an entirely new class of therapeutics aimed at regulating inflammation and host defence.