Plasma/Serum Plasmalogens: Methods of Analysis and Clinical Significance.

Age-related diseases, such as atherosclerosis and dementia, are associated with oxidative stress and chronic inflammation. Peroxisome dysfunction may be related to aging and age-related pathologies, possibly through the derangement of redox homeostasis. The biosyntheses of plasmalogens (Pls), a subclass of glycerophospholipids, are primarily regulated by peroxisomes. Thus, plasma Pls may reflect the systemic functional activity of peroxisomes and serve as potential biomarkers for diseases related to oxidative stress and aging. Recently, we have established three promising analytical methods for plasma/serum Pls using high-performance liquid chromatography with radioactive iodine, liquid chromatography-tandem mass spectrometry, and enzymatic assay. These methods were validated and used to obtain detailed molecular information regarding these molecules. In cross-sectional studies on asymptomatic, coronary artery disease, and elderly dementia individuals, we found that serum choline Pls, particularly those containing oleic and linoleic acid in the sn-2 position of the glycerol backbone, may serve as reliable antiatherogenic biomarkers. Furthermore, we also found that serum ethanolamine Pls were effective in discriminating cognitive impairment. These results support our hypothesis and further studies are clearly needed to elucidate Pls pathophysiologic significance.