Imaging mass spectrometry revealed the production of lyso-phosphatidylcholine in the injured ischemic rat brain

Abstract

To develop an effective neuroprotective strategy against ischemic injury, it is important to identify the key molecules involved in the progression of injury. Direct molecular analysis of tissue using mass spectrometry (MS) is a subject of much interest in the field of metabolomics. Most notably, imaging mass spectrometry (IMS) allows visualization of molecular distributions on the tissue surface. To understand lipid dynamics during ischemic injury, we performed IMS analysis on rat brain tissue sections with focal cerebral ischemia. Sprague-Dawley rats were sacrificed at 24 h after middle cerebral artery occlusion, and brain sections were prepared. IMS analyses were conducted using matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF MS) in positive ion mode. To determine the molecular structures, the detected ions were subjected to tandem MS. The intensity counts of the ion signals of m/z 798.5 and m/z 760.5 that are revealed to be a phosphatidylcholine, PC (16:0/18:1) are reduced in the area of focal cerebral ischemia as compared to the normal cerebral area. In contrast, the signal of m/z 496.3, identified as a lyso-phosphatidylcholine, LPC (16:0), was clearly increased in the area of focal cerebral ischemia. In IMS analyses, changes of PC (16:0/18:1) and LPC (16:0) are observed beyond the border of the injured area. Together with previous reports--that PCs are hydrolyzed by phospholipase A(2) (PLA(2)) and produce LPCs,--our present results suggest that LPC (16:0) is generated during the injury process after cerebral ischemia, presumably via PLA(2) activation, and that PC (16:0/18:1) is one of its precursor molecules.

Mass spectrometry images acylcarnitines, phosphatidylcholines, and sphingomyelin in MDA-MB-231 breast tumor models

“…Mammalian brain tissue, due to its high lipid content, has also been extensively studied by MSI. Ion images of lipid distributions have been obtained for rat (17)(18)(19)(20)(21)(22), mouse ( 23,24 ), and human ( 25,26 ) brain sections. Lipid MSI has also been performed for various types of tumor tissue, such as human brain tumors ( 27 ), seminoma ( 28 ), ovarian cancer ( 29,30 ), myxoid liposarcomas ( 31 ), human astrocytoma ( 32 ), human prostate cancer tissue ( 33 ), colon cancer liver metastasis ( 34 ), and human liver adenocarcinoma ( 35 ).…”

“…The identifi cation of all lipid species involved collisional activation (see Fig. 5 ( 56 ), and following heart ( 16 ) and brain ( 19,57 ) injury. Multiple different bioactive lysophospholipids exhibit pleomorphic effects on multiple cell lineages, including breast and ovarian cancer cells ( 58,59 ).…”

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.…”

From Whole-body Sections Down to Cellular Level, Multiscale Imaging of Phospholipids by MALDI Mass Spectrometry

“…Defects in lipid metabolism play a role in many diseases such as muscular dystrophy and cardiovascular disease. Phospholipids in tissues have been intensively studied by several groups (37,40,(77)(78)(79)(80)(81)(82)(83). In this respect, for optimal recovery of signal, several variables such as the choice of matrix for both imaging and fragmentation, solvent system, and instrument polarity have been investigated (20,84).…”