D-4F, an apolipoprotein A-I mimetic peptide, protects human umbilical vein endothelial cells from oxidized low-density lipoprotein-induced injury by preventing the downregulation of pigment epithelium-derived factor expression.
OBJECTIVE
To investigate the protective effects of D-4F, an apolipoprotein A-I mimetic peptide, on oxidized low-density lipoprotein (ox-LDL)-induced injury of vascular endothelial cells and the potential role of pigment epithelium-derived factor (PEDF).


METHODS
Cytotoxicity was assessed by the apoptotic rate, 3-(4,5-dimethylthiazol-2-y-l)-2,5-diphenyl-2H-tetrazolium bromide assay, and lactate dehydrogenase release. PEDF levels were analyzed with Western blot and quantitative real-time polymerase chain reaction. Redox status was measured by the levels of the reactive oxygen species, malondialdehyde, superoxide dismutase, and nitric oxide.


RESULTS
Ox-LDL reduced cell viability and induced apoptosis and LDH release from human umbilical vein endothelial cells, but the cytotoxic effects of ox-LDL were significantly inhibited by pretreatment with D-4F. Additionally, D-4F could scavenge intracellular reactive oxygen species, suppress the production of lipid peroxides, and improve endogenous antioxidant activity. Ox-LDL decreased PEDF expression in human umbilical vein endothelial cells in a concentration-dependent manner, and this decrease was markedly attenuated by D-4F. However, silencing PEDF by short interfering RNA blocked the inhibitory effects of D-4F on ox-LDL-induced oxidative stress and cellular injury.


CONCLUSIONS
D-4F effectively protects vascular endothelial cells against ox-LDL-induced injury by preventing the downregulation of PEDF expression.
*Division of Cardiovascular Department, Chinese PLA General Hospital, Beijing, China; and †Key Laboratory of Atherosclerosis in Universities of Shandong, Institute of Atherosclerosis, Taishan Medical University, Taian, Shandong, China.
Jie
J
Liu
Shutong
S
Yao
Shuxia
S
Wang
Peng
P
Jiao
Guohua
G
Song
Yang
Y
Yu
Ping
P
Zhu
Shucun
S
Qin
D000595:Amino Acid Sequence; D016632:Apolipoprotein A-I / Q000235:genetics / Q000494:pharmacology*; D019610:Cytoprotection / Q000187:drug effects* / Q000502:physiology; D015536:Down-Regulation / Q000187:drug effects* / Q000502:physiology; D005136:Eye Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D005786:Gene Expression Regulation; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism / Q000633:toxicity*; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D010084:Oxidation-Reduction / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D015843:Serpins / Q000096:biosynthesis*; D000099174:Pigment Epithelium-Derived Factor
D016632:Apolipoprotein A-I; D005136:Eye Proteins; D008077:Lipoproteins, LDL; D009414:Nerve Growth Factors; D017382:Reactive Oxygen Species; D015843:Serpins; D000099174:Pigment Epithelium-Derived Factor; C465468:D-4F peptide