A primary lesion model for arteriosclerotic microplaque formation

Abstract

Proteoheparan sulfate can be adsorbed to a methylated silica surface in a monomolecular layer via its transmembrane hydrophobic protein core domain. Due to electrostatic repulsion, its anionic glycosaminoglycan side chains are stretched out into the blood substitute solution representing a receptor site for specific lipoprotein binding through basic amino acid-rich residues within their apolipoproteins. The binding process was studied by ellipsometric techniques showing that HDL has a high binding affinity to the receptor and a protective effect on interfacial heparan sulfate proteoglycan layers with respect to LDL and Ca²⁺ complexation. LDL was found to deposit strongly at the proteoheparan sulfate, particularly in the presence of Ca²⁺ thus creating the ternary complex formation “proteoglycan-LDL-calcium'. This heterotrimeric complex build-up may be interpreted as arteriosclerotic microplaque formation on the molecular level responsible for the primary lesion. On the other hand, HDL bound to heparan sulfate proteoglycan protected against LDL docking and completely suppressed calcification of the proteoglycan-lipoprotein complex. In addition, HDL and garlic extract were able to reduce the ternary complex deposition.