α-synuclein conformational antibodies fused to penetratin are effective in models of Lewy body disease

Objective: Progressive accumulation of alpha-synuclein (alpha-syn) has been associated with Parkinson's disease (PD) and Dementia with Lewy body (DLB). The mechanisms through which alpha-syn leads to neurodegeneration are not completely clear; however, the formation of various oligomeric species have been proposed to play a role. Antibody therapy has shown effectiveness at reducing alpha-syn accumulation in the central nervous system (CNS); however, most of these studies have been conducted utilizing antibodies that recognize both monomeric and higher molecular weight alpha-syn. In this context, the main objective of this study was to investigate the efficacy of immunotherapy with singlechain antibodies (scFVs) against specific conformational forms of alpha-syn fused to a novel brain penetrating sequence. Method: We screened various scFVs against alpha-syn expressed from lentiviral vectors by intracerebral injections in an alpha-syn tg model. The most effective scFVs were fused to the cell-penetrating peptide penetratin to enhance transport across the blood-brain barrier, and lentiviral vectors were constructed and tested for efficacy following systemic delivery intraperitoneal into alpha-syn tg mice. Result: Two scFVs (D5 and 10H) selectively targeted different alpha-syn oligomers and reduced the accumulation of alpha-syn and ameliorated functional deficits when delivered late in disease development; however, only one of the antibodies (D5) was also effective when delivered early in disease development. These scFVs were also utilized in an enzyme-linked immunosorbent assay (ELISA) assay to monitor the effects of immunotherapy on alpha-syn oligomers in brain and plasma. Interpretation: The design and targeting of antibodies for specific species of alpha-syn oligomers is crucial for therapeutic immunotherapy and might be of relevance for the treatment of Lewy body disease.