Mechanisms and applications of apolipoproteins and apolipoprotein mimetic peptides: Common pathways in cardiovascular disease and cancer

Abstract

Apolipoproteins are the defining functional component of lipoproteins and play critical roles in lipid transport and metabolism. High-density lipoprotein (HDL) and its primary functional constituent, apolipoprotein A-I, are of particular importance because of anti-inflammatory and antioxidant properties. Apolipoprotein mimetic peptides are short-chain amino acids designed to mimic the functions and alpha-helical structure of endogenous apolipoproteins and have demonstrated efficacy in ameliorating animal models of cardiovascular disease (CVD) and cancer. The mechanisms underlying the mimetics are yet to be fully elucidated, but a comprehensive review of the literature suggests that the peptides attack pathways shared in the pathophysiology of both diseases. This review also discusses the many pre-clinical studies on the mimetic peptides, highlighting possible mechanisms at work in each. Proposed mechanisms of protection against CVD and cancer include binding and removal of pro-inflammatory oxidized lipids, reduction in reactive oxygen species, and modulation of immune cell populations. Additionally, nanoparticles (NP) formulations incorporating apolipoprotein mimetic peptides or recombinant apolipoproteins have exhibited anti-atherogenic and anti-cancer activity. To date, clinical trials to assess the effect of reconstituted HDL NPs on CVD outcomes have not shown significant improvement. The large body of successful animal studies on apolipoproteins and apolipoprotein mimetic peptides presents a disconnect between pre-clinical and clinical efficacy, highlighting the need for a more complete understanding of the underlying pathways and mechanisms.