The role of apolipoprotein M and sphingosine 1-phosphate axis in the prevention of atherosclerosis

Previous studies showed that plasma levels of high-density lipoprotein (HDL) cholesterol are inversely related to risk of cardiovascular diseases. However, in the last few decades it became obvious that beyond its plasma level, HDL structure and function have a critical role in its anti-atherogenic efficacy. Apolipoprotein M (ApoM) is an HDL-associated plasma protein affecting HDL metabolism and exhibits various anti-atherosclerotic functions, such as protection against oxidation and regulation of cholesterol efflux. Sphingosine 1-phosphate (S1P) is a potent sphingolipid mediator that regulates numerous cellular responses including cell differentiation and migration, apoptosis and vascular inflammation. The majority of S1P is associated to ApoM containing HDL particles. Therefore, ApoM and S1P content of HDL have an impact on the atherosclerotic process. Moreover, HDL-ApoM and S1P content can be altered in several pathologic conditions such as coronary artery disease. This review covers the currently available data on the contribution of ApoM and S1P to HDL function in health and cardiovascular diseases.