Many diseases such as
arthritis or
atherosclerosis are accompanied by inflammatory processes.
Inflammation is characterized by the infiltration of cells such as neutrophilic granulocytes and (a) the release of
phospholipases [particularly
phospholipase A2 (PLA2)] and (b) the generation of reactive
oxygen as well as
nitrogen species (ROS and RNS). While PLA2 leads to defined lyso products (lacking one acyl residue),
lipid oxidation is characterized by much more complex product patterns, including
lipid peroxides,
aldehydes (by double bond cleavage), and many others. Nevertheless, oxidation processes are highly important under in vivo conditions because molecules with regulatory functions are generated by the oxidation of
lipids and/or
free fatty acids. Therefore,
lipid oxidation products as well as lysolipids are increasingly assumed to represent important disease (bio)markers. Consequently, there is also increasing interest in methods to characterize these products qualitatively and quantitatively.Mass spectrometry (MS) seems to be the method of choice to study (phospho)
lipids changed under inflammatory conditions: nowadays, soft ionization MS methods are regularly used to study oxidative
lipid modifications because of their high sensitivities and the tremendous mass resolutions that are achievable by using modern mass spectrometers. However, experimental care is required to be able to detect all relevant products. Although electrospray ionization (ESI) MS is so far most popular, applications of matrix-assisted
laser desorption and ionization (MALDI) MS are continuously increasing. This review aims to summarize the so far available data on MS analyses of oxidized
lipids as well as lysolipids. In addition to model systems, special attention will be paid to the monitoring of oxidized
lipids and lysolipids under in vivo conditions. It is the aim of this review to provide a critical survey of the advantages and drawbacks of the different MS methods, with the focus on MALDI and ESI.