High Throughput Analysis of Tissue Phosphatidylcholines Revealing Comprehensive Regioisomer Profiles and Their Response to Diet

As structural and functional components of cell membranes, glycerophospholipids (GPLs) play a crucial role in a wide range of physiological processes. Disturbance in GPL homeostasis in tissues and organs are associated with the pathophysiology of various diseases. Further, recent research has indicated that alteration in GPL regioisomeric composition in tissues could be potential biomarkers of diseases. However, the detailed GPL regioisomeric profiles in different tissues and organs remain unknown, largely due to the lack of powerful analytical methods. To tackle this challenge, we recently developed a novel solution for high throughput analysis of GPL regioisomers by integrating UHPLC-ESI-QTOF-MS analysis with an optimized fragmentation model and a calculation software. Using the newly developed method and software, we performed a thorough mapping of phosphatidylcholine (PC) regioisomers in different organs (liver, brain, heart, spleen, lung, testicle, kidney, eye) of male Sprague–Dawley rats fed on different diets, revealing, for the first time, organ-specific profiles of PC regioisomers in rats or any mammals. Furthermore, our study demonstrated that four-week n-3 deficient feeding changed the composition and the relative abundance of PC molecular species and regioisomers, especially those containing n-3 and n-6 PUFAs being the most influenced. Supplementation with docosahexaenoic acid (DHA) in regio- and stereospecifically structured triacylglycerols not only counteracted the changes in PCs induced by n-3 deficient feeding, but also resulted in higher number and relative abundance of DHA-containing molecular species compared to n-3 adequate feeding with normal feed containing α-linolenic acid from soybean. The findings demonstrated that our new analytical method is high throughput and a robust tool suitable for screening the highly complex regiospecific profiles of GPLs in natural lipidomes, having potential for a wide range of application in research and product development in the field of food, nutrition, health.