Identification of Macromolecular Designs for Inhibiting the Atherogenic Effect of Endothelial Scavenger Receptor, LOX-1

Scavenger receptors (SRs) are among the key cell surface proteins related to the progression of atherosclerosis. SRs mediate unregulated uptake of oxidatively modified forms of lipoproteins which initiate the pro-inflammatory signaling cascade and cause excessive lipid accumulation in vascular cells. Vascular endothelial cells predominantly express lectin like oxidized LDL (oxLDL) receptor (LOX-1), a member of the scavenger receptor family. OxLDL recognition and subsequent internalization by LOX-1 has been shown to contribute to all stages of atherosclerosis by 1) promoting reactive oxygen species production, 2) activating proinflammatory signaling, 3) impairing the regulation of vascular tone, and 4) inducing apoptosis. Therefore, LOX-1 is a promising target for atherosclerosis therapies currently under development.

Previously our laboratories demonstrated that a class of amphiphilic macromolecules can competitively inhibit oxLDL uptake by blocking macrophage scavenger receptors. These molecules consist of a sugar (mucic acid) backbone that is covalently linked to four aliphatic arms and poly(ethylene glycol). Using molecular modeling, by docking and scoring approach, a new library of macromolecules has been screened for efficiency of binding to LOX-1. The library includes amphiphilic macromolecules featuring different backbone and/or charge characteristics in an effort to identify the key molecular properties that affect binding to LOX-1. Molecules were built in silico and docked to oxLDL binding domain of LOX-1. Binding energies were calculated by evaluating the highest ranking poses. Modeling results were compared with in vitro competitive oxLDL uptake inhibition experiments utilizing transfected CHO cells that have inducible expression of human LOX-1.

Binding energy values obtained in silico correlated well with in vitro results. Molecules with the most favorable LOX-1 binding (lowest binding energy) exhibited most efficient inhibition of oxLDL uptake. Hydrophobic interactions played a more significant role in binding to LOX-1 than to charge presentation. Due to the multi-faceted importance of LOX-1 in atherogenesis and athero-inflammation, the exhibited inhibition of oxLDL binding to LOX-1 is an important step towards the development of novel macromolecular based therapies.