Objective: To establish a new combination screening system consisted of high-throughput in vitro assay with phenotype-based in vivo assay and to develop anti-amyloid drugs truly effective for Parkinson’s disease.

Background: Amyloid fibril made of alpha-synuclein (aSyn) is a pathological hall mark of Parkinson’s disease (PD) and one of a good target for disease modifying therapy. Several compounds have been analyzed in vitro and reported to have an anti-amyloid effect to aSyn. However, few studies have performed high-throughput screening, because the growth of aSyn fibril is very slow and highly variable. In addition, few studies have performed second in vivo screening to confirm the effect of hit compounds, only focused on one or two compounds interested in. To overcome these limitations, we have developed a new combination screening system of high-throughput in vitro screening followed by in vivo phenotype-based second screening.

Methods: ASyn was purified as previously described (1). Thioflavin T was employed to monitor the kinetics of aSyn fibril formation.To obtain more uniform and faster kinetics, we used zirconia beads. We modified the multi-plate reader to control the shaking speed and interval. We employed 1263 FDA approved compounds library and 20 drugs approved for PD. After the first screening, we performed phenotype-based second screening using C. elegans model. Worms were incubated with drugs and the locomotion were analyzed by high-throughput Worm-Tracker system. Number of synuclein aggregations in the worms were also calculated.

Results: Our revised in vitro screening system showed an excellent value of Z’ factor (> 0.7). Among 1280 drugs, we obtained 19 hit compounds inhibit synuclein aggregation in vitro. Interestingly, some of them were FDA approved drugs for PD or Alzheimer’s disease. Second screening by C. elegans revealed that one of the PD drug inhibit synuclein aggregation in vivo and recovered the motor phenotype of the worm.

Conclusions: We have found that one drug approved for PD inhibited not only aSyn aggregation in vitro but also modified the C elegans model. It is currently planned to investigate the longitudinal changes in CSF before and after the treatment with the drug using our new device ‘HANABI’ (presented in International Congress of MDS 2017 (Ikenaka et al.) and 2018 (Kakuda et al.)).

References: 1) Yagi H., Kusaka E., Hongo K., Mizobata T. & Kawata Y. Amyloid fibril formation of alpha-synuclein is accelerated by preformed amyloid seeds of other proteins: implications for the mechanism of transmissible conformational diseases. J. Biol. Chem. 280, 38609–38616 (2005).

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MDS Abstracts - https://www.mdsabstracts.org/abstract/development-of-anti-amyloid-drugs-for-parkinsons-disease-by-combination-screening-of-high-throughput-in-vitro-assay-and-phenotype-based-c-elegans-system/