Correlative Chemical Imaging Identifies Amyloid Peptide Signatures of Neuritic Plaques and Dystrophy in Human Sporadic Alzheimer's Disease

Objective: Alzheimer's disease (AD) is the most common neurodegenerative disease. The predominantly sporadic form of AD is age-related, but the underlying pathogenic mechanisms remain not fully understood. Current efforts to combat the disease focus on the main pathological hallmarks, in particular beta-amyloid (A beta) plaque pathology. According to the amyloid cascade hypothesis, A beta is the critical early initiator of AD pathogenesis. Plaque pathology is very heterogeneous, where a subset of plaques, neuritic plaques (NPs), are considered most neurotoxic rendering their in-depth characterization essential to understand A beta pathogenicity.Methods: To delineate the chemical traits specific to NP types, we investigated senile A beta pathology in the postmortem, human sporadic AD brain using advanced correlative biochemical imaging based on immunofluorescence (IF) microscopy and mass spectrometry imaging (MSI).Results: Immunostaining-guided MSI identified distinct A beta signatures of NPs characterized by increased A beta 1-42(ox) and A beta 2-42. Moreover, correlation with a marker of dystrophy (reticulon 3 [RTN3]) identified key A beta species that both delineate NPs and display association with neuritic dystrophy.Conclusion: Together, these correlative imaging data shed light on the complex biochemical architecture of NPs and associated dystrophic neurites. These in turn are obvious targets for disease-modifying treatment strategies, as well as novel biomarkers of A beta pathogenicity.

Automated summary

Alzheimer's disease is the most common neurodegenerative disease, and its underlying pathogenic mechanisms are not fully understood. The study focuses on the main pathological hallmarks of the disease, particularly beta-amyloid plaque pathology. By using advanced imaging techniques, the research identified distinct A beta signatures and key A beta species associated with neuritic dystrophy.