Aortic gene expression profiles show how APOA-I levels modulate infammation, lysosomal activity and sphingolipid metabolism in murine atherosclerosis

HDL particles are known to possess several anti-atherogenic properties that include the removal of excess cholesterol from peripheral tissues, the maintenance of endothelial integrity, antioxidant and antiinflammatory activities. ApoA-I overexpression in apoE-deficient (EKO) mice has been shown to increase HDL levels and to strongly reduce atherosclerosis development. The aim of the study was to investigate gene expression patterns associated with atherosclerosis development in the aorta of EKO mice and how HDL plasma levels relate to gene expression patterns at different stages of atherosclerosis development and with different dietary treatments. Methods Eight weeks old EKO mice, EKO mice overexpressing human apoA-I (EKO/hA-I) and wild-type mice as controls were fed either Chow or Western diet for 6 or 22 weeks. Cholesterol distribution among lipoproteins was evaluated and atherosclerosis of the aorta was quantified. High-throughput sequencing technologies were used to analyse the transcriptome of the aorta of the three genotypes in each experimental condition. Results: In addition to the well-known activation of inflammation and immune response, the impairment of sphingolipid metabolism, phagosome-lysosome system and osteoclast differentiation emerged as relevant players in atherosclerosis development. The reduced atherosclerotic burden in the aorta of EKO mice expressing high levels of apoA-I was accompanied by a reduced activation of the immune system markers, as well as reduced perturbation of lysosomal activity and a better regulation of the sphingolipid synthesis pathway Conclusions. ApoA-I modulates atherosclerosis development in the aorta of EKO mice affecting the expression of pathways additional to those associated with inflammation and immune response aortic mRNA profiles of 8-weeks old wild type (WT), APOE (EKO mice), and EKO mice overexpressing human apoA-I (EKO/hA-I) fed either Chow or Western diet for 6 or 22 weeks