大鼠脊髓损伤模型中脂质分布和变化MALDI成像分析

MALDI Imaging Analysis of Lipid Distribution and Change in Rats with Spinal Cord Injury

  • 摘要: 基质辅助激光解吸电离质谱(MALDI-MS)具有软电离性质,可以得到单电荷离子的简洁谱图,是分析生物分子的有力工具。基质辅助激光解吸电离质谱成像(MALDI-MSI)技术为生物分析提供了一种同时成像多种化合物的原位可视化工具。本团队前期发展了一种新型基质(E)-丙基-α-氰-4-羟基肉桂酸盐(CHCA-C3),其适用于分析疏水性蛋白和多肽。本工作将CHCA-C3用于大鼠脊髓损伤(SCI)模型中脂质的检测,对原发性脊髓损伤和继发性脊髓损伤后脊髓中脂质的分布和发生的变化进行原位成像分析。使用CHCA-C3基质,在m/z 500~900范围内成功检测出251个质谱峰。通过比对数据库获得25种脂质,发现其中4种脂质在损伤12 h(急性期)、3天(亚急性期)、7天(亚急性期)呈现明显的差异性。利用分区模型(SM)和主成分分析(PCA)对检测出的251个谱峰进行全面分析,发现在SCI的不同阶段,代谢物分布存在明显变化。本研究结果不仅拓展了CHCA-C3基质在MALDI-MSI中的应用,也为了解脊髓损伤发展过程中脂质分子的变化提供了有意义信息。

     

    Abstract: Lipids are one of the most important biomolecules, where they serve as building blocks for celluar membranes and involve in signal transduction and energy storage. The molecular imaging of lipids is critical for understanding complex biological processes, especially under pathological conditions. Spinal cord injury (SCI) always leads to a severe insult motor and sensory function impairment. The direct physical damage to spinal cord will lead to secondary injury consisted of uncontrollable oxidative stress and sever neuroinflammation, subsequently causes lipid peroxidation. The oxidative stress and lipid peroxidation in SCI result in alterations of lipid metabolism and homeostasis, thus induce the changes and heterogeneous spatial distribution of lipids. Therefore, mapping the lipid distribution in injured spinal cords is necessary for understanding the pathological microenvironment of SCI. Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is a powerful imaging tool for in situ visualization of numerous biomolecules simultaneously. To improve the matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) performance of lipids, developing new matrices is urged. Our previous studies have shown that the matrix of (E)-propyl α-cyano-4-hydroxylcinnamylate (CHCA-C3) exhibits excellent performance for detecting hydrophobic proteins and peptides, which has good co-crystallization performace and increased hydrophobicity. Herein, CHCA-C3 was applied for MALDI-MSI of lipids after SCI, and the changes and spatial distribution of lipids at different times after SCI were analyzed. Compared with CHCA, CHCA-C3 shows profound improvement in lipid detection, that more MS peaks are obtained with higher intensity. Using CHCA-C3, 251 MS peaks are observed in MS spectra, and 25 of them are identified as lipids by searching against database. Moreover, the difference of lipid distribution in injured spinal cords at various time after SCI was investigated. And four lipids, including cholesterol ester CE (20:4), phosphatidylcholine PC (32:1), PC (34:0) and PC (40:0), show significant difference in the spatial distribution at 12 h (acute stage), 3 day (subacute stage) and 7 day (subacute stage) after SCI. Subsequently, the segmentation model (SM) and principal component analysis (PCA) were performed to comprehensive analyzing the 251 MS peaks, and obvious differences are found at spectra obtained from injured spinal cord at different injured phases. In conclusion, this research not only expands the application of CHCA-C3 in MALDI-MSI, but also provides the changes and spatial distribution of lipids in SCI. And the result provides the in-depth understanding of lipidomic changes in SCI, as well as supports the development of new therapeutic strategies for SCI treatment.

     

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