Global changes in phospholipids identified by MALDI MS in rats with focal cerebral ischemia

Abstract

has been given to cellular phospholipid analyses compared with protein or peptide analyses. However, recent progress in mass spectrometric analysis has enabled the identifi cation of small cellular components including phospholipids and quantifi cation of their cellular expression profi les ( 3, 4 ).ESI MS is widely used for phospholipid analysis. Currently, MALDI imaging MS (MALDI IMS) has become the prime choice because it provides additional advantages over ESI, including simple sample preparation and an abundance of information about molecular structures and spatial data ( 3,(5)(6)(7)(8)(9). The principal advantage of MALDI IMS is its ability to ionize molecules directly from the surface of tissue samples, which can demonstrate the spatial distribution of molecules of interest. However, MALDI IMS must be further improved to resolve technical problems such as the ambiguity of structural determination, unequal ionization effi ciencies of different compounds, and complications due to uneven tissue structure. Glycerophospholipids can be classifi ed according to their head groups, linkage between the polar chain and glycerol backbone, and variability in their FA composition ( 9 ). Depending on the presence of amine or hydroxyl structures on their head group, phospholipids can be ionized in either positive or negative mode. The ionization effi ciency of lipids can also be affected by their head group structure. Occasionally, it is diffi cult to perform MALDI IMS analysis twice in both positive and negative ionization modes on the same tissue sample to identify lipid composition Abstract Neuronal membrane phospholipids are highly affected by oxidative stress caused by ischemic injury. Thus, it is necessary to identify key lipid components that show changes during ischemia to develop an effective approach to prevent brain damage from ischemic injury. The recent development of MALDI imaging MS (MALDI IMS) makes it possible to identify phospholipids that change between damaged and normal regions directly from tissues. In this study, we conducted IMS on rat brains damaged by ischemic injury and detected various phospholipids that showed unique distributions between normal and damaged areas of the brain. Among them, we confi rmed changes in phospholipids such as lysophosphatidylcholine, phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin by MALDI IMS followed by MS/MS analysis. These lipids were present in high concentrations in the brain and are important for maintenance of cellular structure as well as production of second messengers for cellular signal transduction. Our results emphasize the identifi cation of phospholipid markers for ischemic injury and successfully identifi ed several distinctly located phospholipids in ischemic brain tissue.

Heat Shock Protein 70.1 (Hsp70.1) Affects Neuronal Cell Fate by Regulating Lysosomal Acid Sphingomyelinase

“…For example, the new mass spectroscopic technique MALDI MS revealed the changes of phospholipids, such as lysophosphatidylcholine, phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin, in rat brains after focal cerebral ischemia (26). Studies have revealed that inducible Hsp70.1 has protective effects against ischemia and oxidative injury (27,28); however, whether its protection correlates with membrane lipids remains to be elucidated.…”

Global changes of phospholipids identified by MALDI imaging mass spectrometry in a mouse model of Alzheimer's disease

“…As PLs constitute the majority of the biological molecules in cells and whole tissues that are analyzed in MALDI-MS experiments (9)(10)(11), this is a useful method to monitor PL changes in certain biological states. After adipose tissue, brain tissue contains the second highest concentration of PLs (20-25%) (12)(13)(14). MALDI IMS has emerged as the prime choice for PL analysis because it provides advantages over other ionization methods such as ESI MS, including simple sample preparation and the inclusion of spatial information ( 15,16 ).…”

“…Brains from three mice were analyzed for each experimental group. Following the whole tissue IMS analysis, the data were analyzed using FlexImaging and ClinProTools, as described previously ( 12 ). Figure 2 presents a comparison of the average spectra obtained from the whole brain tissue sections after normalization using ClinProTools 2.2 in positive ( Fig.…”

“…(Bruker Daltonics). Mass calibration was performed with external standards using lipid-mixed calibration standards with m/z ranges of 674-834 Da (positive ion mode) and 564-906 Da (negative ion mode) prior to data acquisition to achieve a mass accuracy of better than 50 ppm ( 12,24 ). A mass resolution of M/ ⌬ M ‫ف‬ 20,000 was typically achieved in the mass window of PLs.…”

Metabolomics predicts stroke recurrence after transient ischemic attack

“…19 LysoPC(16:0) by itself increases on brain after stroke 20,21 where it mediates phagocyte recruiting 22 that can contribute to ischemic brain injury 23 and also produces neuroinflammatory effects when applied on CNS. 24 All these results could pinpoint a beneficial effect of reduced LysoPC(16:0) levels that argue against our claim that it marks an early SR risk, but although high levels of plaque LysoPC(16:0) are correlated with high plasma and plaque levels of Lp-PLA2, plasma LysoPC(16:0) levels are not.…”