Efficient RT-QuIC seeding activity for α-synuclein in olfactory mucosa samples of patients with Parkinson’s disease and multiple system atrophy

摘要

Background:Parkinson’s disease(PD)is a neurodegenerative disorder whose diagnosis is often challenging because symptoms may overlap with neurodegenerative parkinsonisms.PD is characterized by intraneuronal accumulation of abnormalα-synuclein in brainstem while neurodegenerative parkinsonisms might be associated with accumulation of eitherα-synuclein,as in the case of Multiple System Atrophy(MSA)or tau,as in the case of Corticobasal Degeneration(CBD)and Progressive Supranuclear Palsy(PSP),in other disease-specific brain regions.Definite diagnosis of all these diseases can be formulated only neuropathologically by detection and localization ofα-synuclein or tau aggregates in the brain.Compelling evidence suggests that trace-amount of these proteins can appear in peripheral tissues,including receptor neurons of the olfactory mucosa(OM).Methods:We have set and standardized the experimental conditions to extend the ultrasensitive Real Time Quaking Induced Conversion(RT-QuIC)assay for OM analysis.In particular,by using human recombinantα-synuclein as substrate of reaction,we have assessed the ability of OM collected from patients with clinical diagnoses of PD and MSA to induceα-synuclein aggregation,and compared their seeding ability to that of OM samples collected from patients with clinical diagnoses of CBD and PSP.Results:Our results showed that a significant percentage of MSA and PD samples inducedα-synuclein aggregation with high efficiency,but also few samples of patients with the clinical diagnosis of CBD and PSP caused the same effect.Notably,the final RT-QuIC aggregates obtained from MSA and PD samples owned peculiar biochemical and morphological features potentially enabling their discrimination.Conclusions:Our study provide the proof-of-concept that olfactory mucosa samples collected from patients with PD and MSA possess important seeding activities forα-synuclein.Additional studies are required for(i)estimating sensitivity and specificity of the technique and for(ii)evaluating its application for the diagnosis of PD and neurodegenerative parkinsonisms.RT-QuIC analyses of OM and cerebrospinal fluid(CSF)can be combined with the aim of increasing the overall diagnostic accuracy of these diseases,especially in the early stages.