HDL Are Host Defense Lipoproteins

Hundreds of proteins and lipid species give HDLs (high-density lipoproteins) their polydispersity and multifunctionality. Studies have shown that plasma levels of HDL cholesterol (HDL-C) and apo AI (apolipoprotein AI), as well as HDL particle measures recorded by nuclear magnetic resonance spectroscopy, are associated with many clinical end points, including cardiovascular disease, diabetes, chronic kidney disease, and infections. These conditions all share inflammation as a pathogenic process. HDL particles and their specific components interfere with several steps in the inflammatory process. (1) They prevent dysmetabolism and eliminate or inactivate the causes and triggers of inflammation, including infectious agents, cholesterol, and oxidized lipids. (2) They modulate the activity of cellular and humoral components of innate and acquired immune systems. (3) They help limit or repair tissue damage or systemic homeostatic disturbances caused by inflammation. However, confrontation with the causes of inflammation and the organism’s additional responses to inflammation can modify HDL’s composition and components so that these particles lose or gain beneficial or adverse properties, respectively. Therefore, HDL particles are components of host defense and remain interesting targets for managing multiple inflammatory diseases beyond atherosclerosis.