Reduction of arteriosclerotic nanoplaque formation and size by fluvastatin in a receptor-based biosensor model

Abstract

Proteoheparan sulfate can be adsorbed onto 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, thereby 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 suggesting that HDL has a high binding affinity and a protective effect on interfacial heparan sulfate proteoglycan layers with respect to LDL and Ca(2+) complexation. LDL was found to be deposited strongly at the proteoheparan sulfate-coated surface, particularly in the presence of Ca(2+), apparently through complex formation 'proteoglycan-low density lipoprotein-calcium'. This ternary complex build-up may be interpreted as arteriosclerotic nanoplaque formation on the molecular level responsible for the arteriosclerotic primary lesion. In a receptor-based biosensor application, this system was tested on its reliability to unveil possible acute pleiotropic effects of the lipid lowering drug fluvastatin. The VLDL/IDL/LDL and VLDL/IDL/LDL/HDL plasma fractions from a high risk patient with dyslipoproteinaemia and type 2 diabetes mellitus showed the start of arteriosclerotic nanoplaque formation at a normal blood Ca(2+) concentration, with a strong increase at higher Ca(2+) concentrations. Nanoplaque formation and size of the HDL-containing lipid fraction remained well below that of the LDL-containing lipid fraction. Fluvastatin, whether applied acutely to the patient (one single 80 mg slow release matrix tablet) or in a 2-month medication regimen, markedly slowed down this process of ternary aggregational nanoplaque build-up and substantially inhibited nanoplaque size development at all Ca(2+) concentrations used. The acute action gave no significant change in lipid concentrations of the patient. Furthermore, after nanoplaque generation, fluvastatin, similar to HDL, was able to reduce nanoplaque formation and size. These immediate effects of fluvastatin have to be taken into consideration when interpreting the clinical outcome of long-term studies.

The significance of lipid peroxidation in cardiovascular disease

“…3). This ternary aggregational formation on endothelial cell membranes and vascular matrices may mimic the arteriosclerotic "primary lesion" by causing endothelial dysfunction with its restricted NO release [35], the very earliest stage of atherogenesis on a molecular level before any cellular reactivity [4]. As already pointed out, nanoplaque formation and size were substantially diminished.…”

“…In a number of investigations [1,[3][4][5][6][7][8][9][10], a good correlation has been observed between in vivo biomarkers and risk factors, on one hand, and lipoprotein risk factor deposition to HS-PG under accelerated in vitro conditions. While the latter could most realistically be performed with endothelial cells adhered to methylated silica surfaces for ellipsometry and microscopy, analogous results were found with simpler and more robust endothelial model surfaces, in which HS-PG was simply adsorbed to methylated silica surfaces [13].…”

“…Lipoproteins were isolated by sequential preparative ultracentrifugation essentially as described previously [4].…”

“…From a series of previous preclinical and clinical studies it appeared, that many biomarkers, e.g., hs-CRP, cytokines, and liver values are up-or down-regulated in the subthreshold range, but so much the more have an important early diagnostic, preventive and prognostic significance [4][5][6][7][8][9]. The picture is the more complicated in that some inflammatory biomarkers, e.g., MPO and Lp(a) behave inversely with regards to cytokine balance.…”

“…Our clinical trials with statins [3,4], ginkgo [6,10], ω3-fatty acids [11] and blackcurrant extract [12] unravelled this network of biomarker interactions and demonstrated its usefulness for theranostics.…”