Effects of LDL Apheresis System on the Expression of Genes Involved in Lipoprotein Metabolism and Inflammation in Homozygotes for Familial Hypercholesterolemia

Overview

Familial hypercholesterolemia (FH) is an autosomal codominant single-gene disorder caused by mutations in the LDL receptor gene that disrupt the normal clearance of LDL particles from the plasma compartment. Heterozygous patients present a 2- to 3-fold raise in plasma LDL-cholesterol (C) concentrations, tendinous xanthomatosis and premature atherosclerotic coronary heart disease (CHD), usually occurring between the age of 35 and 55 years. Since the mid-1970s, LDL-C has been removed from the blood of patients using plasmapheresis, and this technique has been shown to improve the life expectancy of FH homozygotes. LDL apheresis selectively removes LDL particles but not immunoglobulins and other beneficial proteins, thereby overcoming a potential drawback of the traditional plasmapheresis method. LDL-C is effectively reduced by more than 60% immediately after LDL apheresis, although LDL levels rebound rapidly. Dextran sulfate adsorption is a commonly apheresis technique used in familial hypercholesterolemia patients. In this apheresis plasma is separated from red blood cells and passed over columns of cellulose beads containing dextran sulfate which binds apolipoprotein B (apoB) by a highly selective electrostatic binding mechanism. Since LDL, very-low density lipoprotein (VLDL), and Lipoprotein (a) all contain apoB, dextran sulfate adsorption apheresis selectively reduces these lipoproteins while having little effect on the non-apoB containing HDL particles. In clinical practice, LDL apheresis reduces the rate of future cardiovascular events and has been postulated to have additional effects on potentially pro-atherogenic factors. Some proteins have been identified with adhesive characteristics to lipoproteins, rheological, immunological and inflammation relevant proteins16-19 that influence microcirculation as well as the inflammatory response. However, no studies have yet to investigate the impact of LDL apheresis on the expression of different genes involved in cardiovascular disease. The main objective of the present research project is to investigate the impact of the LDL apheresis dextran sulfate adsorption system on the messenger ribonucleic acid (mRNA) expression of genes involved in cardiovascular disease using microarrays analysis in 9 FH homozygotes.