engleski

Sphingomyelin is elevated in cerebrospinal fluid of Alzheimer's disease patients

Background: Lipid alterations in Alzheimer’s disease (AD) brains have been reported. However, only few of them focused on lipid changes in the cerebrospinal fluid (CSF), which is the most informative fluid source for neurodegenerative disease prognosis and diagnosis, due to its constant physical contact with the brain. Although phospholipids levels in the CSF are low, developments in mass spectrometry (MS) have enabled fast and sensitive detection of lipid species even in complex biological matrixes. Methods: We developed an on-line HPLC/MS method for phospholipid profiling in the CSF based on nano-HPLC separation using Amide column and detection with electrospray (ESI) quadrupole – time of flight (QTOF) MS. We achieved good separation, reproducibility and sensitivity for monitoring major phospholipid classes in the CSF: phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI) and sphingomyelin (SM). To elucidate phospholipid changes in the CSF, a pilot study was performed on CSF samples (N=16) from individuals with probable AD and non-demented controls. Results: The HPLC elution order of each phospholipid classes in CSF was: PE (~33.5-35.0 min), PC (~34.5-35.5 min), PI (~36.0-37.0 min) and SM (~37.5-38.5) The most intense signal corresponded to PC species followed by SM, PI and PE with ratios to PC intensity of approximately 0.3, 0.15 and 0.1, respectively. Five PE, six PC, six PI and eight SM species have been detected with average relative standard deviation of 16%, 3%, 6% and 8% respectively. Our pilot study showed statistically significant increase of SM levels (24.3% ± 2.4%) in the CSF of probable AD individuals vs. controls. Conclusion: Our findings indicate that sphingomyelin levels in the CSF could potentially provide a new lead in AD biomarker research as well as in elucidating the role of SM in AD pathogenesis. This work was supported by the grants of The National Foundation for Science, Higher Education and Technological Development of the Republic of Croatia.

Alzheimer's disease; cerebrospinal fluid; lipids; mass spectrometry; phospholipids; sphingomyelin

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