Abstract 660: Reverse-D4F (Rev-D4F), an Apolipoprotein-AI Mimetic Peptide, Reduces Plaque Macrophage Content in Apolipoprotein E-null Mice
Background: Class A amphipathic helical peptide analogs of apo-AI mimetic peptides are potential emerging therapeutic approaches to improve HDL function to decrease atherosclerosis. Using retro-inversal sequence approach to synthesize Reverse (Rev) D-4F apo-AI mimetic peptide with D-amino acids and reverse order to maintain exact alignment and superimposable to the parent L-4F peptide, we have recently shown that Rev D-4F peptide significantly reduces aortic root atherosclerosis in apo E-null mice without affecting plasma total and HDL-cholesterol (Qin, et al. Circulation 2005, 112 (17): II-110). In order to define the mechanisms, using in-vivo and in-vitro studies we investigated the effect of Rev D-4F on aortic lesion macrophage content in apo E-null mice, and human aortic endothelial cell (HAEC) LDL oxidation, VCAM-1 expression, and monocyte adhesion, key pathobiological processes involved in atherogenesis.
Methods: Three groups of 4 week old apoE-null mice were fed chow diet, and administered water (control), Rev-D4F, or L-4F mimetic peptides (1.6 mg/day, n=6/group) orally in drinking water for 6 weeks. Lesion macrophage content was measured by immunohistochemical staining using monoclonal anti-mouse MOMA2 antibody as a specific marker for monocyte/macrophage in aortic root sections. HAEC LDL oxidation, VCAM-1 expression, and adhesion assays were done by measuring thiobarbituric acid reactive substances (TBARS), Real-time PCR analysis, ELISA, and adhesion rate using fluorescently labeled monocytes respectively.
Results and Conclusions: Rev-D4F significantly (p=0.0009) reduced macrophage content in lesions by 47% compared to controls. L-4F mimetic peptide had no effect on macrophage content. In-vitro studies indicated that Rev D-4F significantly inhibited endothelial cell LDL oxidation, TNF-α- and LPS-induced VCAM-1, and oxidized LDL-induced monocyte adhesion. The data suggest that Rev-D4F, through inhibiting inflammatory and LDL oxidative events, reduces endothelial monocyte migration, lesion macrophage content and atherosclerosis.