A human apolipoprotein E mimetic peptide reduces atherosclerosis in aged apolipoprotein E null mice

Apolipoprotein E (apoE) is well known as an antiatherogenic protein via regulating lipid metabolism and inflammation. We previously reported that a human apoE mimetic peptide, EpK, reduced atherosclerosis in apoE null (apoE(-/-)) mice through reducing inflammation without affecting plasma lipid levels. Here, we construct another human apoE mimetic peptide, named hEp, and investigate whether expression of hEp can reduce atherosclerotic lesion development in aged female apoE(-/-) mice with pre-existing lesions. We found that chemically synthesized hEp significantly decreased cholesterol accumulation induced by oxidized low density lipoprotein and the expression of inflammatory cytokines TNF alpha and IL-6 induced by lipopolysaccharide in macrophages. In an in vivo study, Lv-hEpGFP lentiviruses were intravenously injected into 9 month-old apoE(-/-) mice. Mice were then fed a chow diet for 18 weeks. Results showed that in comparison to the Lv-GFP lentivirus injection (Lv-GFP) group, Lv-hEp-GFP lentivirus injection achieved hepatic hEp expression and secretion in apoE(-/-) mice. It was observed that hEp expression significantly reduced plasma VLDL and LDL cholesterol levels and decreased aortic atherosclerotic lesions. This was accompanied by an increase of LDL receptor expression and a reduction of TNFa and IL-6 mRNA levels in the liver. Moreover, expression of hEp increased plasma paraoxonase-1 activity and decreased plasma myeloperoxidase activity and serum amyloid A levels. Our study provides evidence that hEp may be developed as a promising therapeutic apoE mimetic peptide for atherosclerosis-related cardiovascular diseases through its induction of plasma VLDL/LDL cholesterol clearance as well as its anti-oxidative and anti-inflammatory activities.