Menzel Jan Philipp, Birrer Fabienne E, Stroka Deborah, Masoodi Mojgan
Department of Clinical Chemistry, Inselspital, Bern University Hospital, 3010 Bern, Switzerland.
Department of Visceral Surgery and Medicine, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland.
Anal Chem. 2025 Apr 29;97(16):8791-8800. doi: 10.1021/acs.analchem.4c06503. Epub 2025 Apr 14.
Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most prevalent liver disorder worldwide and can progress to steatohepatitis. Elevated de novo lipogenesis (DNL) is a key contributor to hepatic steatosis. Fatty acid (FA) desaturation produces several unsaturated lipid isomers that are structurally very similar but have diverse biological functions. However, due to their structural similarity, many conventional mass spectrometry approaches cannot detect such metabolic alterations. Thus, we introduce the Skylite (Skyline-based lipid isomer retention time evaluation) workflow using conventional liquid chromatography-mass spectrometry (LC-MS) to identify important isomer features. Retention times of isomeric phosphatidylcholines are compared with the well-characterized human plasma reference standard NIST 1950. Retention time trends correlate well with fixed-charge derivatized FA in liquid chromatography and ozone-induced dissociation mass spectrometry data. The interpretation is supported by double bond diagnostic fragments in LC-MS/MS experiments of epoxidized hydrolyzed fatty acids. We investigate hepatic lipid profiles, focusing on esterified fatty acids in two mouse models of metabolic dysfunction-associated steatohepatitis (MASH). Out of 37 phosphatidylcholine sum compositions, the workflow identifies 123 lipid features. Importantly, CCl-induced and melanocortin-4 receptor knockout mice on a western diet (WD) have significantly higher levels of mead acid, branched-chain fatty acid, and -7 PUFA incorporated into phosphatidylcholines. While the MASH mouse liver tissues contain notable amounts of -7 PUFA, no -10 PUFA were detected, potentially indicating a unique desaturation pattern. The screening for altered lipid isomer profiles bridges the gap between high-throughput analyses and specialized structure-resolved techniques.
代谢功能障碍相关脂肪性肝病（MASLD）是全球最普遍的肝脏疾病，可进展为脂肪性肝炎。从头脂肪生成（DNL）增加是肝脂肪变性的关键因素。脂肪酸（FA）去饱和产生几种结构非常相似但具有不同生物学功能的不饱和脂质异构体。然而，由于它们的结构相似性，许多传统的质谱方法无法检测到这种代谢改变。因此，我们引入了Skylite（基于Skyline的脂质异构体保留时间评估）工作流程，使用传统的液相色谱-质谱（LC-MS）来识别重要的异构体特征。将异构磷脂酰胆碱的保留时间与特征明确的人血浆参考标准NIST 1950进行比较。保留时间趋势与液相色谱和臭氧诱导解离质谱数据中固定电荷衍生的FA密切相关。环氧化水解脂肪酸的LC-MS/MS实验中的双键诊断片段支持了这一解释。我们研究了肝脏脂质谱，重点关注代谢功能障碍相关脂肪性肝炎（MASH）的两种小鼠模型中的酯化脂肪酸。在37种磷脂酰胆碱总和组成中，该工作流程识别出123种脂质特征。重要的是，在西方饮食（WD）条件下，CCl诱导的和黑皮质素-4受体敲除的小鼠中，纳入磷脂酰胆碱的蜂花酸、支链脂肪酸和-7多不饱和脂肪酸（PUFA）水平显著更高。虽然MASH小鼠肝脏组织含有大量的-7 PUFA，但未检测到-10 PUFA，这可能表明一种独特的去饱和模式。对改变的脂质异构体谱的筛选弥合了高通量分析和专门的结构解析技术之间的差距。
