Next-generation active immunization approach for synucleinopathies: implications for Parkinson's disease clinical trials

Immunotherapeutic approaches are currently in the spotlight for their potential as disease-modifying treatments for neurodegenerative disorders. The discovery that alpha-synuclein (alpha-syn) can transmit from cell to cell in a prion-like fashion suggests that immunization might be a viable option for the treatment of synucleinopathies. This possibility has been bolstered by the development of next-generation active vaccination technology with short peptides-AFFITOPEs(A (R)) (AFF)- that do not elicit an alpha-syn-specific T cell response. This approach allows for the production of long term, sustained, more specific, non-cross reacting antibodies suitable for the treatment of synucleinopathies, such as Parkinson's disease (PD). In this context, we screened a large library of peptides that mimic the C-terminus region of alpha-syn and discovered a novel set of AFF that identified alpha-syn oligomers. Next, the peptide that elicited the most specific response against alpha-syn (AFF 1) was selected for immunizing two different transgenic (tg) mouse models of PD and Dementia with Lewy bodies, the PDGF- and the mThy1-alpha-syn tg mice. Vaccination with AFF 1 resulted in high antibody titers in CSF and plasma, which crossed into the CNS and recognized alpha-syn aggregates. Active vaccination with AFF 1 resulted in decreased accumulation of alpha-syn oligomers in axons and synapses, accompanied by reduced degeneration of TH fibers in the caudo-putamen nucleus and by improvements in motor and memory deficits in both in vivo models. Clearance of alpha-syn involved activation of microglia and increased anti-inflammatory cytokine expression, further supporting the efficacy of this novel active vaccination approach for synucleinopathies.