Cyclodextrins Inhibit Replication of Scrapie Prion Protein in Cell Culture

Abstract

Prion diseases are fatal neurodegenerative disorders that are caused by the conversion of a normal host-encoded protein, PrP C , to an abnormal, disease-causing form, PrP Sc . This paper reports that cyclodextrins have the ability to reduce the pathogenic isoform of the prion protein PrP Sc to undetectable levels in scrapie-infected neuroblastoma cells. Beta-cyclodextrin removed PrP Sc from the cells at a concentration of 500 μM following 2 weeks of treatment. Structure activity studies revealed that antiprion activity was dependent on the size of the cyclodextrin. The half-maximal inhibitory concentration (IC 50 ) for beta-cyclodextrin was 75 μM, whereas α-cyclodextrin, which possessed less antiprion activity, had an IC 50 of 750 μM. This report presents cyclodextrins as a new class of antiprion compound. For decades, the pharmaceutical industry has successfully used cyclodextrins for their complex-forming ability; this ability is due to the structural orientation of the glucopyranose units, which generate a hydrophobic cavity that can facilitate the encapsulation of hydrophobic moieties. Consequently, cyclodextrins could be ideal candidates for the treatment of prion diseases.