Characterization of pathology-inducing α-synuclein species from human diseased brain tissue
Synucleinopathies are a group of neurodegenerative diseases characterized by the presence of pathological accumulations of misfolded, phosphorylated -synuclein (Syn) protein. Multiple lines of evidence indicate that synucleinopathy disease progression is driven by a prion-like process of transmission of a pathologic form of Syn. One potential therapeutic approach to prevent cell-to-cell propagation is to target this transmissible species with selective antibodies. In this study, a rodent primary neuronal culture reporter system was developed to monitor induction of detergent-insoluble, phosphorylated (pS129) aggregates of Syn. Induction of pS129 Syn pathology was observed with both synthetic Syn fibrils (PFFs) and brain lysates from multiple system atrophy (MSA) patients but not Syn monomers or human brain lysate controls. The induction-competent species in MSA lysates could be enriched by high-speed centrifugation suggesting that it is present as a high molecular weight aggregate. Furthermore, samples derived from brain lysates from Parkinsons disease (PD) and Dementia with Lewy Bodies (DLB) patients also induced pS129 Syn pathology, but required longer incubation times. Lastly, the potential of Syn selective antibodies to immunodeplete induction-competent forms of Syn from both PFF and synucleinopathy brain samples is described. The results demonstrate that antibodies targeting the C-terminal of Syn are most effective for immunodepletion of pathology-inducing forms of Syn from samples derived from human synucleinopathy brains. Furthermore, the data support the hypothesis that antibodies that recognize a C-terminal epitope and exhibit selectivity for oligomeric forms over monomeric forms of Syn represent a desirable target for immunotherapy for synucleinopathy patients.