Quantification of CSF biomarkers using an electrochemiluminescence-based detection system in the differential diagnosis of AD and sCJD

Abstract

The identification of reliable diagnostic tools for the differential diagnosis between sporadic Creutzfeldt-Jakob Disease (sCJD) and Alzheimer's disease (AD) remains impeded by the existing clinical, neuropathological and molecular overlap between both diseases. The development of new tools for the quantitative measurement of biomarkers is gaining experimental momentum due to recent advances in high-throughput screening analysis and with the optimization of assays for their quantification in biological fluids, including cerebrospinal fluid (CSF). Electrochemiluminescence (ECL)-based immunoassays have demonstrated to achieve clinical quality performance in a variety of sample types due to its high sensitivity and dynamic range. Here, we quantified the CSF levels of Tau-protein, β-amyloid 1-42 (Aβ42) and α-synuclein, as important biomarkers in CSF used in the differential diagnosis of neurodegenerative disorders in 12 AD, 12 sCJD and 12 control cases by singleplex ECL-based technology. Its performance has been compared to classical enzyme-linked immunosorbent assays (ELISA) to confront their clinical accuracy. ECL-based technology validates previous data obtained with ELISA and presents a higher performance in the discrimination of three analysed groups as determined by increased area under the curve (AUC) values for the three biomarkers. Importantly, α-synuclein levels detected by ECL allow an excellent discrimination between sCJD cases and AD and control cases, unveiling a new clinical approach for the differential diagnosis of sCJD.

Alpha-, Beta-, and Gamma-synuclein Quantification in Cerebrospinal Fluid by Multiple Reaction Monitoring Reveals Increased Concentrations in Alzheimer′s and Creutzfeldt-Jakob Disease but No Alteration in Synucleinopathies

“…We could confirm previous observations of increased CSF ␣Syn concentrations in CJD (33)(34)(35)(36) and observed also a tendency to elevated concentrations in AD (37)(38)(39). ␣Syn has been suggested as a biomarker for the differential diagnosis of AD and CJD (33) which is supported by our data.…”

“…␣Syn has been suggested as a biomarker for the differential diagnosis of AD and CJD (33) which is supported by our data. However, ␣Syn determination has some drawbacks including susceptibility to blood contamination.…”

Interlaboratory validation of cerebrospinal fluid α‐synuclein quantification in the diagnosis of sporadic Creutzfeldt‐Jakob disease

“…Several indications suggested that the U‐plex human aSyn kit test would be a good candidate to validate its potential interlaboratory performance in the diagnosis of sCJD as the final step before its introduction in clinical practice. On one hand, we previously demonstrated the increased sensitivity of electrochemiluminescence platforms over classical colorimetric assays in the quantification of CSF aSyn [6], leading to a better discriminatory power between sCJD and non‐CJD cases. On the other hand, according to the manufacturer, the U‐plex human aSyn kit was developed following “fit for purpose” principles [37] and is consistent with guidance from the Clinical and Laboratory Standards Institute (http://www.clsi.org).…”

CSF biomarkers in neurodegenerative and vascular dementias

“…Recently, it has been suggested that a-synuclein is specifically regulated in sCJD (Kasai et al, 2014;Llorens et al, 2015a;Mollenhauer et al, 2008a). The underlying mechanism leading to an increase of a-synuclein in the CSF is still unknown.…”