LDLR-/- mice aorte: Control vs DHA

The omega-3 fatty acid docosahexaenoic acid (DHA) has potent anti-atherogenic properties but its mechanisms of action at the vascular level remain poorly explored. Knowing the broad range of molecular targets of omega-3 fatty acids, microarray analysis was used to open-mindedly evaluate the effects of DHA on aorta gene expression in LDLR-/- mice and better understand its local anti-atherogenic action . Mice were fed an atherogenic diet and received daily oral gavages with oils rich in oleic acid or DHA. Bioinformatics analysis of microarray data first identified inflammation and innate immunity as processes the most affected by DHA supplementation within aorta. More precisely, several down-regulated genes were associated with the inflammatory functions of macrophages (e.g. CCL5, CCR7), cell movement (e.g. ICAM-2, SELP, PECAM-1), and the major histocompatibility complex (e.g. HLA-DQA1, HLA-DRB1). Interestingly, the expression of several genes were identified as specifc biomarkers of macrophage polarization and their changes suggested a preferential orientation towards a M2 reparative phenotype. This observation was supported by the upstream regulator analysis highlighting the involvment of three main regulators of macrophage polarization, namely PPARγ (z-score=2.367, p=1.50x10-13), INFγ (z-score=-2.797, p=2.81x10-14) and NFκB (z-score=2.360, p=6.32x10-9). Moreover, immunohistological analysis of aortic root revealed an increased abundance of Arg1 (+111%, p=0.01), a specific biomarker of M2 macrophage.The present study showed for the first time that DHA supplementation during atherogenesis is associated with protective modulation of inflammation and innate immunity pathways within aorta putatively through the orientation of plaque macrophages towards a M2 reparative phenotype. Mice (LDLR-/-) Aorta samples. 2 groups: Control (K), DHA (C). Biological replicates=8. Dye switch.