Imaging mass spectrometry (IMS) of cortical lipids from preclinical to severe stages of Alzheimer's disease

Abstract

Alzheimer's disease (AD) is a progressive neurodegenerative disease affecting millions of patients worldwide. Previous studies have demonstrated alterations in the lipid composition of lipid extracts from plasma and brain samples of AD patients. However, there is no consensus regarding the qualitative and quantitative changes of lipids in brains from AD patients. In addition, the recent developments in imaging mass spectrometry methods are leading to a new stage in the in situ analysis of lipid species in brain tissue slices from human postmortem samples. The present study uses the matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS), permitting the direct anatomical analysis of lipids in postmortem brain sections from AD patients, which are compared with the intensity of the lipid signal in samples from matched subjects with no neurological diseases. The frontal cortex samples from AD patients were classified in three groups based on Braak's histochemical criteria, ranging from non-cognitively impaired patients to those severely affected. The main results indicate a depletion of different sulfatide lipid species from the earliest stages of the disease in both white and gray matter areas of the frontal cortex. Therefore, the decrease in sulfatides in cortical areas could be considered as a marker of the disease, but may also indicate neurochemical modifications related to the pathogenesis of the disease.