Integrated Spatial Multi-Omics Study of Postmortem Brains of Alzheimer's Disease

Pathological hallmark of Alzheimer's disease (AD) is characterized by the accumulation and aggregation of amyloid beta (A beta) peptides into extracellular plaques of the brain. Clarification of the process of how soluble A beta starts to assemble into amyloid fibrils is an essential step in elucidating the pathogenesis of AD. In our previous study, A beta proteoforms including fulllength A beta 40 and A beta 42/43 with N- and C-terminal truncated forms were visualized in postmortem brains from AD patients with matrix-assisted laser desorption/ionization-based mass spectrometry imaging (MALDI-MSI). In this study, A beta proteoforms were consistently visualized by an updated protocol, and uncharacterized peptides such as A beta 1-29 and A beta 10-40 in AD brains were also visualized. To decipher neurotoxic effects of A beta in patients' brains, here we integrate liquid chromatography tandem mass spectrometry (LC-MS/MS) based shotgun proteomics with laser microdissection (LMD) excised tissue samples as well as direct tissue imaging with MALDI-MSI. With this approach, we have highlighted dynamic alterations of microtubule associating proteins (MAPs) including MAP1A, MAP1B and MAP2 as well as AD dominant proteins including APP, UCHL1, SNCA, and APOE. Of note, as lipid dysregulation has been implicated with AD pathology, we have challenged to integrate proteomics and lipid imaging for AD and control brain tissue. Spatial multi-omics is also valid to uncover molecular pathology of white matter as well as grey matter and leptomeningeal area, for example, by visualizing heme in patients' postmortem brains.