Aβ-polyacrolein aggregates: Novel mechanism of plastic formation in senile plaques

High levels of acrolein (H2CHCCHO) occur in Alzheimer's brain. Amyloid-β (Aβ) peptide co-localizes with acrolein presumably due to Aβ-induced lipid peroxidation. Focal production of acrolein may yield a transient elevation in the concentration of acrolein that may be susceptible to polymerization via basic latex polymer chemistry. Following incubation of Aβ with acrolein (16-750 mM), we observed the formation of thin plastic fragments that were extensively punctuated. Planar aggregates stained for protein and for cross-β structures suggesting an Aβ-polyacrolein colloidal mixture. Depending on acrolein concentration and incubation time, we observed uniformly sized planar aggregates (approximately 10 μm2) or monolayers (>100 mm2) of thin polyacrolein films embedded with Aβ oligomers. The ability of Aβ to catalyze the polymerization of acrolein is likely due to Aβ's surfactant and redox properties. These observations suggest that plastic in the form of Aβ-polyacrolein latexes may exist in neural tissue contributing to the pathogenesis of Alzheimer's disease.