Impact of seed amplification assay and surface-enhanced Raman spectroscopy combined approach on the clinical diagnosis of Alzheimer’s disease

Background The current diagnosis of Alzheimer’s disease(AD)is based on a series of analyses which involve clinical,instrumental and laboratory findings.However,signs,symptoms and biomarker alterations observed in AD might overlap with other dementias,resulting in misdiagnosis.Methods Here we describe a new diagnostic approach for AD which takes advantage of the boosted sensitivity in biomolecular detection,as allowed by seed amplification assay(SAA),combined with the unique specificity in biomolecular recognition,as provided by surface-enhanced Raman spectroscopy(SERS).Results The SAA-SERS approach supported by machine learning data analysis allowed efficient identification of pathological Aβoligomers in the cerebrospinal fluid of patients with a clinical diagnosis of AD or mild cognitive impairment due to AD.Conclusions Such analytical approach can be used to recognize disease features,thus allowing early stratification and selection of patients,which is fundamental in clinical treatments and pharmacological trials.

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

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.