Non-enzymatic glycosylation of apolipoprotein A-I and its functional consequences

High-density lipoproteins (HDL) are believed to protect against atherosclerosis by promoting the process of reverse cholesterol transport. This process involves different steps including efflux of cellular cholesterol, cholesterol esterification and lipid transport and exchange. Apolipoprotein (apo) A-I, the major HDL apolipoprotein, and the HDL-associated enzyme lecithin-cholesterol acyltransferase (LCAT), which uses apo A-I as a cofactor, play a crucial role in reverse cholesterol transport. HDL may be classified into species according to their apolipoprotein content. Recent data concerning HDL particles indicate that lipoproteins containing apo A-I but not apo A-II (LpA-I) are more effective carriers of free cholesterol and are associated with a protective effect against coronary heart disease. In vitro studies have shown that glycosylated HDL are functionally abnormal and may be considered atherogenic. Our study considers the different impacts of non-enzymatic glycosylation of apo A-I or protein-HDL on the reverse cholesterol transport process.