Abstract
Background Endothelial cell injury, induced by dyslipidemia, is the initiation of atherosclerosis, resulting in an imbalance in endothelial fatty acid (FA) transport. Pigment epithelial-derived factor (PEDF) is an important regulator in lipid metabolism. We hypothesized that PEDF is involved in endothelium-mediated FA uptake under hyperlipidemic conditions. Methods and Results Circulating PEDF levels were higher in patients with atherosclerotic cardiovascular disease than in normal individuals. However, decreasing trends of serum PEDF levels were confirmed in both wild-type and apolipoprotein E-deficient mice fed a long-term high-fat diet. Apolipoprotein E-deficient/PEDF-deficient mice were generated by crossing PEDF-deficient mice with apolipoprotein E-deficient mice, and then mice were fed with 24, 36, or 48 weeks of high-fat diet. Greater increases in body fat and plasma lipids were displayed in PEDF-deficient mice. In addition, PEDF deficiency in mice accelerated atherosclerosis, as evidenced by increased atherosclerotic plaques, pronounced vascular dysfunction, and increased lipid accumulation in peripheral tissues, whereas injection of adeno-associated virus encoding PEDF exerted opposite effects. Mechanistically, PEDF inhibited the vascular endothelial growth factor B paracrine signaling by reducing secretion of protein vascular endothelial growth factor B in peripheral tissue cells and decreasing expression of its downstream targets in endothelial cells, including its receptors (namely, vascular endothelial growth factor receptor-1 and neuropilin-1), and FA transport proteins 3 and 4, to suppress endothelial FA uptake, whereas PEDF deletion in mice activated the vascular endothelial growth factor B signaling pathway, thus causing markedly increased lipid accumulation. Conclusions Decreasing expression of PEDF aggravates atherosclerosis by significantly impaired vascular function and enhanced endothelial FA uptake, thus exacerbating ectopic lipid deposition in peripheral tissues.