L-4F, an Apolipoprotein A-1 Mimetic, Restores Nitric Oxide and Superoxide Anion Balance in Low-Density Lipoprotein-Treated Endothelial Cells

Abstract

Background-Low-density lipoprotein (LDL) impairs endothelial cell function by uncoupling endothelial nitric oxide synthase (eNOS) activity, which allows superoxide anion (O 2 ·Ϫ ) to be generated rather than nitric oxide (·NO). Recent reports indicate that apolipoprotein (apo) A-1 mimetics inhibit the development of atherosclerotic lesions in LDL receptor-null mice. Here we hypothesize that L-4F, an apoA-1 mimetic that inhibits atherosclerosis induced by hypercholesterolemia, protects endothelial cell function by preventing LDL from uncoupling eNOS activity. Methods and Results-Bovine aortic endothelial cells were incubated with LDLϮL-4F, and changes in A23187-stimulated ·NO and O 2 ·Ϫ generation were determined by ozone chemiluminescence and superoxide dismutaseinhibitable ferricytochrome c reduction, respectively. Western analysis of eNOS immunoprecipitates was used to determine effects of LDL and L-4F on heat shock protein 90 (hsp90)

ApoA-I Mimetic Peptides with Differing Ability to Inhibit Atherosclerosis Also Exhibit Differences in Their Interactions with Membrane Bilayers

“…Furthermore, even some peptides derived from the sequence of apoJ also have anti-inflammatory properties, although they have very different sequences (15). The present study demonstrates that one of the 3F peptides, 3F-2, which was able to inhibit LDL-induced monocyte chemotaxis (12), also protects against atherosclerotic lesion formation when administered to apoE null mice that spontaneously develop atherosclerosis, whereas the analogous peptide 3F 14 (Fig. 1) that did not inhibit LDLinduced monocyte chemotaxis does not inhibit lesion formation.…”

“…Peptides were purified using a preparative HPLC system (Beckman Gold), and the purity of the peptides was ascertained by mass spectral analysis and analytical HPLC. For obtaining 14 Clabeled peptides, during the last step of the synthesis, 14 C-labeled acetic acid (American Radiolabeled Chemicals, Inc. St Louis, MO) was used to acetylate the peptide instead of normal acetic acid.…”

“…Peptide Administration and Lesion Quantitation-Peptides 3F-2 and 3F 14 were solubilized in physiological saline, and concentration was determined using A 280 as described earlier (12,13). 4-Week-old female mice were randomized into three groups.…”

“…At the end of the study, blood samples were taken under anesthesia by retro-orbital bleeding, and hearts were excised and subjected to histological examination and quantification of lesion area as described earlier (16). 14 . The wheel is projected along the axis of the helix from the N to C terminus with the hydrophobic side facing downward.…”

“…Despite their small size, some of these peptides are as potent as apoA-I in solubilizing lipid, inhibiting hemolysis caused by lytic peptides, inhibiting oxidized phospholipid-induced monocyte chemotaxis, scavenging lipid hydroperoxides from LDL (12), and maintaining endothelial nitric-oxide synthase activity in the presence of atherogenic concentrations of LDL (14). Studies using these peptide analogs clearly show that in vitro anti-inflammatory activities are sensitive to the arrangement of residues on the hydrophobic face of the helix (12).…”