Anti-inflammatory and recycling properties of an apolipoprotein mimetic peptide, Ac-hE18A-NH2

Abstract

Apolipoprotein E (apoE) exerts prominent anti-inflammatory effects and undergoes recycling by target cells. We previously reported that the peptide, Ac-hE18A-NH2, composed of the receptor binding domain (LRKLRKRLLR) of apoE covalently linked to the Class A amphipathic peptide 18A, dramatically lowers plasma cholesterol and lipid hydroperoxides and enhances paraoxonase activity in dyslipidemic animal models. The objective of this study was to determine whether this peptide, analogous to apoE, exerts anti-inflammatory effects and undergoes recycling under in vitro conditions. Pulse chase studies using [125I]-Ac-hE18A-NH2 in THP-1 derived macrophages and HepG2 cells showed greater amounts of intact peptide in the cells at later time points indicating recycling of the peptide. Ac-hE18A-NH2 induced a 2.5 fold increase in preβ-HDL in the conditioned media of HepG2 cells. This effect persisted for three days after removal of the peptide from culture medium. Ac-hE18A-NH2 also induced the secretion of cell-surface apoE from THP-1 macrophages. In addition, the peptide increased cholesterol efflux from THP-1 cells by an ABCA-1 independent mechanism. Moreover, Ac-hE18A-NH2 inhibited LPS-induced vascular cell adhesion molecule-1 (VCAM-1) expression, and reduced monocyte adhesion in human umbilical vein endothelial cells (HUVECs). It also reduced the secretion of interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) from THP-1 macrophages even when administered post-LPS and abolished the 18-fold increase in LPS-induced mRNA levels for MCP-1 in THP-1 cells. Taken together, these results suggest that addition of the putative apoE receptor-domain to the Class A amphipathic peptide, 18A results in a peptide that, similar to apoE, recycles, thus enabling the potentiation and prolongation of its anti-atherogenic and anti-inflammatory effects. Such a peptide has great potential as a therapeutic agent in the management of atherosclerosis and other inflammatory diseases.

Anti-inflammatory and cholesterol-reducing properties of apolipoprotein mimetics: a review

“…While Ac-hE18A-NH 2 is rapidly cleared from the circulation after IV administration, it continues to exert signifi cant benefi cial effects on aortic lesions for up to a month after suspending peptide administration in mouse models of atherosclerosis ( 135 ). Subsequent studies revealed that Ac-hE18A-NH 2 induces the release of PON-1 and lipid-poor pre ␤ -HDL particles from hepatocytes and also promotes apoE secretion from hepatocytes and macrophages ( 131,133,136,137 ). These studies further showed that Ac-hE18A-NH 2 is recycled by cells, thus enabling the potentiation and prolongation of its anti-atherogenic and anti-infl ammatory effects ( 131 ).…”

“…1 ) ( 93, 122 ). The peptide was able to mediate cholesterol effl ux independently of ABCA1 and had the additional advantage of facilitating cholesterol clearance due to the presence of the receptor binding domain ( 131 ). In vivo administration of Ac-hE18A-NH 2 has been shown to reduce plasma cholesterol in mouse and rabbit models of atherosclerosis ( 122,132,133 ).…”

“…Subsequent studies revealed that Ac-hE18A-NH 2 induces the release of PON-1 and lipid-poor pre ␤ -HDL particles from hepatocytes and also promotes apoE secretion from hepatocytes and macrophages ( 131,133,136,137 ). These studies further showed that Ac-hE18A-NH 2 is recycled by cells, thus enabling the potentiation and prolongation of its anti-atherogenic and anti-infl ammatory effects ( 131 ). These results suggest that the apoE mimetic peptide Ac-hE18A-NH 2 , analogous to apoE, exerts cytoprotective effects that are independent of effects on plasma cholesterol (138)(139)(140).…”

Recombinant High-Density Lipoprotein Formulations

“…The peptide stimulated cholesterol efflux similar to native proteins on a molar basis and reduced atherosclerosis in hyperlipidemic mice. Currently, this compound has entered clinical development (Artery Therapeutics, Danville, CA) [55]. A different peptide, a 10-amino acid long oral peptide derived from apoJ is termed D-[113-122] apoJ containing a class G*-helix.…”

Oral administration of L-mR18L, a single domain cationic amphipathic helical peptide, inhibits lesion formation in ApoE null mice

“…The ability of plasma from peptide-treated and control animals to promote monocyte adhesion to endothelial cells was assessed by bovine aortic endothelial cell (BAEC) assay ( 7,23 ). BAEC were grown to 80% confl uency in 24-well plates.…”