Dietary Lipid-initiated Host Immune Regulation through Altered Lipid Metabolite Production and Intestinal Bacteria

Abstract

ω6-polyunsaturated fatty acid (PUFA) metabolites represented by arachidonic acid promote inflammation, while, ω3-PUFAs represented by eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are known to exhibit anti-inflammatory effects. However, the mechanisms of anti-inflammatory effects by ω3-PUFA have been unknown for a long time. Recent progress of lipid analytical techniques allow the identification of ω3-PUFA-derived lipid mediators such as resolvins, protectins, and maresins with pro-resolution and anti-inflammatory activities. We recently identified 17,18-epoxyeicosatetraenoic acid (17,18-EpETE) as a new class of EPA metabolites, which has anti-allergic and antiinflammatory effect. The anti-inflammatory effects were mediated by inhibiting neutrophil migration in G protein-coupled receptor (GPR) 40-dependent manner. Accumulating evidence has revealed that ω3-PUFAs affect the intestinal bacteria, and consequently regulate immune systems. In this review, we introduce the development and control of allergic and inflammatory diseases via changes in lipid metabolites and intestinal bacteria initiated by dietary oils.