Oxysterols: From Physiological Tuners to Pharmacological Opportunities

Oxysterols are oxygenated forms of cholesterol generated via autooxidation by free radicals and reactive oxygen species, or formed enzymatically by a variety of enzymes such as those involved in the synthesis of bile acids. Although found at very low concentrations in vivo, these metabolites play key roles in health and disease, particularly in development and regulating immune cell responses, by binding to effector proteins such as LXRalpha, RORgamma and Insig and directly or indirectly regulating transcriptional programs that affect cell metabolism and function. In this review we summarise the routes by which oxysterols can be generated and subsequently modified to other oxysterol metabolites, and highlight their diverse and profound biological functions and opportunities to alter their levels using pharmacological approaches.