Exploring the Aβ Plaque Microenvironment in Alzheimer’s Disease Mice by Multimodal Lipid-Protein-Histology Imaging on a Benchtop Mass Spectrometer

Amyloid-β (Aβ) plaque deposits in the brain are a hallmark of Alzheimer’s disease (AD) neuropathology. Plaques consist of complex mixtures of peptides like Aβ _1-42 , characteristic lipids such as gangliosides, and they are targeted by reactive microglia and astrocytes. In pharmaceutical research and development it is therefore a formidable challenge to contextualize different biomolecular classes and cell types of the Aβ plaque microenvironment in a coherent experimental workflow on a single tissue section and on a benchtop imaging reader. Here, we developed such a workflow that combines lipid MALDI mass spectrometry imaging using a vacuum-stable matrix with histopathology stains and with MALDI HiPLEX-immunohistochemistry of plaques and multiple protein markers on a bench-top imaging mass spectrometer. The three data layers consisting of lipid, protein markers, and histology can be co-registered and evaluated together. Multimodal data analysis suggests extensive co-localization of Aβ plaques with the peptide precursor protein, with a defined subset of lipids and with reactive glia cells on a single brain section of APP/PS1 AD model mice. Plaque-associated lipids like ganglioside GM2 and phosphatidylinositol PI38:4 isoforms were readily identified using the tandem MS-capabilities of the mass spectrometer. Taken together, our data suggests that complex pathology involving multiple lipids, proteins and cell types can be interrogated by this spatial multiomics workflow on an easy-to-use benchtop mass spectrometer.