An update on oxysterol biochemistry: New discoveries in lipidomics

Highlights: • Oxysterols can regulate both the innate and adaptive immune systems. • Oxysterols can be tumour suppressors and on cometabolites. • Oxysterols can inhibit or activate the Hh signalling pathway. Oxysterols are oxidised derivatives of cholesterol or its precursors post lanosterol. They are intermediates in the biosynthesis of bile acids, steroid hormones and 1,25-dihydroxyvitamin D_3. Although often considered as metabolic intermediates there is a growing body of evidence that many oxysterols are bioactive and their absence or excess may be part of the cause of a disease phenotype. Using global lipidomics approaches oxysterols are underrepresented encouraging the development of targeted approaches. In this article, we discuss recent discoveries important in oxysterol biochemistry and some of the targeted lipidomic approaches used to make these discoveries.