Abstract 310: Oxidized LDL-binding Cationic Peptides and Proteins in Inflammation and Atherosclerosis: Novel Insights

Abstract

Background: Apolipoprotein A1 and apolipoprotein E mimetic peptides have attracted attention due to their ability to reduce atherosclerosis and exhibit antioxidant, anti-inflammatory, and hypolipidemic properties. We previously reported that the non-lipoprotein-related Lys-Arg-rich cationic peptides have anti-inflammatory properties both in vitro and in vivo. In this study, we have determined whether ApoB100 of low density lipoprotein (N-LDL), which is Lys-Arg rich, has similar properties. Methods: 5F-mimetic peptide of ApoA1, LL27 derived from the anti-microbial peptide CAMP, and a human glycodelin derived peptide, were commercially synthesized. N-LDL was prepared and used. The ability of these peptides and protein to neutralize charges of modified lipoproteins, as well as attenuate macrophage uptake and inflammation, were analyzed. Oxidized LDL (Ox-LDL) was pretreated with increasing concentrations of peptides and N-LDL to evaluate charge neutralizing properties of the peptides as well as that of the protein (ApoB100). RAW cells were incubated with LPS or Ox-LDL pretreated with and without peptides and N-LDL. RNA was isolated from treated cells and real time PCR was performed using mouse IL-1α and IL-6 primers. Results: Cationic peptides as well as ApoB100 protein of N-LDL decomposed the peroxide content of 13-HPODE. Incubation of Ox-LDL and Ac-LDL with the peptides as well as ApoB100 resulted in charge neutralization as noted by agarose gel electrophoresis. Pre-incubation of the peptides and N-LDL with modified lipoproteins reduced the uptake of the latter by macrophages and foam cell formation as detected by Oil-Red O staining. Reduced inflammation was observed in the presence of N-LDL as compared to LPS/Ox-LDL. Conclusions: Based on these studies, we postulate that cationic peptides and protein might have properties that would a) affect events that are unrelated to lipid lowering, b) might play an additional role in immune competent cells, including macrophages, and c) might interact with other biologically important anionic molecules, including lipids and proteins. We also predict that lysine-rich cationic peptides and proteins could have therapeutic potential in reducing CVD/atherosclerosis-associated inflammation.