Methodology to detect oxidised phospholipids and their relevance in disease

Unsaturated membrane phospholipids are susceptible to oxidation, either by reactive oxygen species or enzymatically, to generate a complex mixture of peroxy and hydroxyl species. They can then spontaneously decompose to truncated oxidised phospholipids composed of aldehyde, carboxyl and hydroxyl species of five to nine carbon atoms chain length, many of which exhibit potent biological activities. In addition, aldehydes can form Schiff's base reactions with protein lysines to form oxidised lipid:protein adducts. While a selection of oxidised phospholipids have been characterised in detail by a range of mass spectrometry techniques, including direct infusion and liquid chromatography mass spectrometry, there are relatively few reports of comprehensive analyses of oxidised phospholipids in disease states. Oxidised phospholipid species are widely thought to be central to the pathology of many diseases, but there is relatively little direct evidence to confirm this in vivo. This review provides an overview of the various analytical methodologies and then summarises their application to examples of chronic and acute disease, cardiovascular disease and acute respiratory distress syndrome, respectively. It highlights the gaps in information and indicates directions for future research.