Intracellular Gene Regulation Via Engineered Nanolipoblockers for Inhibition of Cholesterol Uptake

           Atherosclerosis, the pathogenic accumulation of low-density lipoprotein (LDL) within the blood vessel walls, is a leading cause of death worldwide. Current treatments do not sufficiently lower cholesterol in many patients suffering from hypercholesterolemia and all patients may suffer from adverse side effects, such as gastrointestinal complaints and myopathy. While systemic therapies inhibit LDL synthesis, our approach involves the localized management of oxidized LDL within the vascular wall through anionic nanolipoblockers (NLBs) and macrophage-targeted drugs. The design of optimal NLBs is the major objective of this research. We have recently shown that through receptor blocking, the NLBs reduce foam cell formation, a hallmark of accumulation of cholesterol or atherogenesis (Chnari et al, Biomacromolecules, 2006); however, their effect on cellular gene expression is unclear. In this study, we investigated the effects of the NLBs on selected genes regulating atherogenesis and inflammation, with the goal of identifying the most anti-atherogenic NLB configurations. Additionally, we assessed using cholesterol accumulation assays and RT-PCR gene expression studies the biological effects of using NLB's for two functions: blocking of receptors and drug carrying potential. The latter was tested by formulating NLBs encapsulated with GW3965, a hydrophobic drug agonist for Liver X Receptors (LXRs), a nuclear receptor family that promotes efflux of internalized cholesterol. We have identified a set of genes (pro-atherogenesis vs. anti-atherogenesis) that are sensitively altered by specific configurations of NLBs. This information will be key to comprehensively evaluate the biological efficacy of NLBs as possible nanoformulations against vascular disease.