Therapeutic Approaches to Prion Diseases

Combination of structure-based virtual screening, molecular docking and molecular dynamics approaches for the discovery of anti-prion fibril flavonoids

Prion diseases are a group of rare neurodegenerative diseases caused by the structural conversion of cellular prion into Scrapie prion resulting aggregated fibrils. Therapy of prion diseases has been developed for several decades, especially drug designs based on the structure of prion monomers. Unfortunately, none of the designed anti-prion drugs function well clinically. To fight against prion fibrils, a drug design based on the precise structure of mammalian prion fibrils is highly required. Fortunately, based on the advantage of newly advanced cryo-electron microscopy (cryo-EM) in the deconvolution of large complexes, three prion fibril structures were resolved in the last 2 years. Based on the cryo-EM solved prion fibril structures, we are able to find some molecules fighting against prion fibrils. Quercetin, one flavonoid molecule in the polyphenol group, has been found to disaggregate the prion fibrils in vitro. In this study, we performed the molecular docking and molecular dynamics simulation on quercetin-like molecules possessing pharmacological properties to evaluate the anti-prion ability of tested molecules. As a result, four quercetin-like molecules interact with prion fibril and decrease the β-strand content by converting some β-strands into loop and helical structures to disintegrate the existing fibril structure. The results of this study are significant in the treatment of prion diseases, and the approaches used in this study are applicable to other amyloid diseases.

Therapeutic strategies for identifying small molecules against prion diseases

Prion diseases are fatal neurodegenerative disorders, for which there are no effective therapeutic and diagnostic agents. The main pathological hallmark has been identified as conformational changes of the cellular isoform prion protein (PrP^C) to a misfolded isoform of the prion protein (PrP^Sc). Targeting PrP^C and its conversion to PrP^Sc is still the central dogma in prion drug discovery, particularly in in silico and in vitro screening endeavors, leading to the identification of many small molecules with therapeutic potential. Nonetheless, multiple pathological targets are critically involved in the intricate pathogenesis of prion diseases. In this context, multi-target-directed ligands (MTDLs) emerge as valuable therapeutic approach for their potential to effectively counteract the complex etiopathogenesis by simultaneously modulating multiple targets. In addition, diagnosis occurs late in the disease process, and consequently a successful therapeutic intervention cannot be provided. In this respect, small molecule theranostics, which combine imaging and therapeutic properties, showed tremendous potential to cure and diagnose in vivo prion diseases. Herein, we review the major advances in prion drug discovery, from anti-prion small molecules identified by means of in silico and in vitro screening approaches to two rational strategies, namely MTDLs and theranostics, that have led to the identification of novel compounds with an expanded anti-prion profile.

Novel screening approaches for human prion diseases drug discovery

Introduction: Human prion diseases are rare fatal neurodegenerative diseases caused by the misfolding and aggregation of the prion protein in the form of infectious prions. So far, these diseases are incurable. One of the major difficulties in identifying suitable drugs is the availability of robust preclinical screening methods. All molecules identified have been screened using cell-based assays and in vivo murine models. The existence of a continuum of prion strains has hampered the identification of efficacious molecules modulating the progression of different forms of the disease. Areas covered: The advent of new in vitro screening methodologies is allowing for novel strategies to develop new compounds that could interfere with a broad range of diseases. In particular, two innovative techniques named Real Time Quaking Induced Conversion (RT-QuIC) and Protein Misfolding Cyclic Amplification (PMCA) have opened new venues for testing compounds in a rapid a reproducible way. These are discussed within. Expert opinion: For human prion diseases, one major hurdle has been a well-defined screening methodology. In other animal species, cell-based assays have been employed that could replicate animal prions indefinitely. Such a tool for human prion diseases is still missing. Therefore, the advent of RT-QuIC and PMCA has proven instrumental to overcome this limitation.

The genetic Creutzfeldt-Jakob disease with E200K mutation: analysis of clinical, genetic and laboratory features of 30 Chinese patients

Genetic Creutzfeldt-Jakob disease (gCJD) with E200K mutation is one of the common subtypes of human genetic prion diseases worldwide. In this study, we systematically analyzed 30 Chinese E200K gCJD cases for their epidemiological, clinical, laboratory and genetic features. The patients came from 12 different provinces, majority in northern part of China. The onset age varied from 42 to 71 year-old (y), with the median of was 57 y. The CYP4X1 gene rs9793471 SNP was tested. Only one patient’s rs9793471 genotype was GA and the others’ were AA. The gender ratio (M: F) was 1:1.73 (11:19). The foremost symptoms and clinical progression of Chinese E200K gCJD patients were quite similar as sporadic CJD cases. Only a few cases (4/30) recalled clearly disease related family history. 74.1% (20/27), 86.7% (26/30) and 50.0% (13/26) of the cases were CSF 14-3-3 positive, sCJD associated abnormalities on MRI and special PSWC on EEG, respectively. The median clinical duration was 9 months (varying from 2 to 26 months). All 30 Chinese E200K gCJD patients were M129M and E219E homozygous. 21 members from 3 families conducted PRNP sequencing and 16 asymptomatic carriers of E200K mutation with M129M and E219E homozygous were identified. This is the largest study on E200K gCJD patients in China, which would benefit to the knowledge of E200K gCJD.

Patent highlights August-September 2017

A snapshot of noteworthy recent developments in the patent literature of relevance to pharmaceutical and medical research and development.