lysophosphatidylethanolamine and Non-alcoholic-Fatty-Liver-Disease

Lysophosphatidylethanolamines (LysoPEs) are the partial hydrolysis products of phosphatidylethanolamine. Despite the unique in vitro bioactivities of LysoPEs, there are limited reports on the pathophysiological role of LysoPEs in the serum, due to the lack of sensitive analytical methods for determination of each molecular species in clinical samples. Herein, we developed a highly sensitive quantitative method to profile the serum LysoPE species by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with selected reaction monitoring (SRM). The internal standard (IS), chemically synthesized in-house, and the lineup of seven major LysoPE species were used in this study. The limits of detection and quantification for each LysoPE species ranged within 0.5-3.3 pmol/mL and 1.0-5.0 pmol/mL, respectively. The combined concentrations of LysoPEs in the serum from healthy subjects (n = 8) and the patients with non-alcoholic fatty liver diseases (NAFLD) including simple steatosis (SS, n = 9) and non-alcoholic steatohepatitis (NASH, n = 27) were 18.030 ± 3.832, 4.867 ± 1.852, and 5.497 ± 2.495 nmol/mL, respectively. The combined and individual concentrations of LysoPEs, except for LysoPE 18:0, significantly decreased in the patients with NAFLD compared with those for the healthy subjects. However, no significant difference was observed between the SS and NASH groups. Our proposed LC-MS/MS method is valid and has advantages of small sample volume, high sensitivity, and simultaneous absolute quantitation for multiple molecular species. This method may enable diagnostic evaluation and elucidation of the as-yet uncovered pathophysiological role of LysoPEs.

Topics: Case-Control Studies; Chromatography, Liquid; Female; Humans; Limit of Detection; Lysophospholipids; Male; Non-alcoholic Fatty Liver Disease; Reference Standards; Reproducibility of Results; Tandem Mass Spectrometry; Young Adult

Even though lysophospholipids have attracted much interest in recent years on account of their unique bioactivity, research related to lysophospholipids is usually hampered by problems associated with standard sample preparation and discrimination of regioisomers. Herein, we demonstrate a quick tin-chemistry-based synthetic route to lysophosphatidylethanolamines (LPEs) and its application in the positional analysis of hepatic LPEs in non-alcoholic steatohepatitis (NASH) model mice. We found that the preference of hepatic LPE regioisomer largely depends on the unsaturation of acyl chain in both control and NASH model mice. In addition, hepatic C18:2-LPE and C20:5-LPE levels were significantly lower in the NASH model mice than those in the control. The LC/MS technique based on the library of LPE regioisomers allows an accurate observation of hepatic LPE metabolism and might provide useful information to elucidate yet ambiguous pathogenesis of NASH.

Topics: Animals; Chromatography, High Pressure Liquid; Disease Models, Animal; Liver; Lysophospholipids; Mass Spectrometry; Mice; Molecular Structure; Non-alcoholic Fatty Liver Disease; Tin