| Sumario: | Background and aims: Low-density lipoprotein (LDL) aggregation is nowadays considered a therapeutic target in atherosclerosis. DP3, the retro-enantio version of the sequence Gly1127-Cys1140 of LRP1, efficiently inhibits LDL aggregation and foam cell in vitro formation. Here, we investigate whether DP3 modulates atherosclerosis in a humanized ApoB100, LDL receptor (LDLR) knockout mice (Ldlr / hApoB100 Tg) and determine the potential LDL-related underlying mechanisms. Methods: Tg mice were fed an HFD for 21 days to induce atherosclerosis and then randomized into three groups that received a daily subcutaneous administration (10 mg/kg) of i) vehicle, ii) DP3 peptide, or iii) a non-active peptide (IP321). The in vivo biodistribution of a fluorescent-labeled peptide version (TAMRA-DP3), and its colocalization with ApoB100 in the arterial intima, was analyzed by imaging system (IVIS) and confocal mi-croscopy. Heart aortic roots were used for atherosclerosis detection and quantification. LDL functionality was analyzed by biochemical, biophysical, molecular, and cellular studies. Results: Intimal neutral lipid accumulation in the aortic root was reduced in the DP3-treated group as compared to control groups. ApoB100 in LDLs from the DP3 group exhibited an increased percentage of α-helix secondary structures and decreased immunoreactivity to anti-ApoB100 antibodies. LDL from DP3-treated mice were pro-tected against passive and sphingomyelinase (SMase)-induced aggregation, although they still experienced SMase-induced sphingomyelin phospholysis. In patients with familial hypercholesterolemia (FH), DP3 efficiently inhibited both SMase-induced phospholysis and aggregation. Conclusions: DP3 peptide administration inhibits atherosclerosis by preserving the α-helix secondary structures of ApoB100 in a humanized ApoB100 murine model that mimicks the hallmark of human hypercholesterolemia.
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