(75b) 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.