Novel approaches in diagnosis and therapy of Creutzfeldt-Jakob disease

The scrapie prion protein, PrP(Sc), as well as its peptide fragment, PrP106-126, are toxic on neuronal cells, resulting in cell death by an apoptotic, rather than necrotic mechanism. The apoptotic process of neuronal cells induced by prion protein supports diagnosis and offers potential targets for therapeutic intervention of the prion diseases. Among the cerebrospinal fluid (CSF) proteins, which may serve as markers of neuronal cell death associated with prion diseases, the 14-3-3 protein(s) turned out to be the most promising one. A new sensitive assay allows the detection of even small changes in the normally low levels of these proteins. In vitro, the toxic effects displayed by PrP(Sc) and its peptide fragment can be blocked by antagonists of N-methyl-D-aspartate (NMDA) receptor channels, like Memantine. Also Flupirtine, a non-opiod analgesic drug, which is already in clinical use, was found to display in vitro a strong cytoprotective effect on neurons treated with PrP(Sc) or PrP106-126. This drug acts like a NMDA receptor antagonists, but does not bind to the receptor. Clinical trials on prion diseases with Flupirtine are in progress. Flupirtine was found to enhance the intracellular levels of the antiapoptotic protein Bcl-2 and the antioxidative agent glutathione (GSH). Due to its favourable pharmacokinetic profile, Flupirtine is considered to be a promising drug to prevent neuronal death in Creutzfeldt-Jakob disease (CJD) and other neurodegenerative disorders occurring with age, e.g. Alzheimer's disease.