A novel antibody‐free mass spectrometry panel of CSF biomarkers for synaptic dysfunction

Abstract

AbstractBackgroundOne of the earliest events and the best correlate to cognitive decline in neurodegenerative diseases, such as Alzheimer’s disease (AD), is synaptic dysfunction and degeneration. Thus, identifying and validating new biomarkers capable of quantifying synaptic degeneration for use as prognostic biomarkers would be very valuable for diagnostic purposes. We have developed a novel assay in which 17 synaptic proteins are simultaneously quantified in cerebrospinal fluid (CSF). The proteins in the panel include but are not limited to: synucleins, neuronal pentraxins, SNARE proteins and neurogranin. In a pilot study, we previously observed that several of these proteins may serve as synaptic biomarkers for AD. In this follow‐up study we aimed to confirm our previous results as well as expand to other neurodegenerative disease such as frontotemporal lobar degeneration (FTLD) and disorders with α‐synuclein pathology.MethodSample preparation of 100 µL CSF samples was performed in a consecutive three‐step process constituting of stable isotope labeled peptide standards addition, tryptic digestion followed by purification by solid‐phase extraction. For quantification was micro‐high‐performance liquid chromatography‐mass‐spectrometry (triple quadrupole) used. A cross‐sectional study including controls (n=47), AD (n=63), FTLD (n=103) and α‐synuclein patients (n=22) was performed.ResultIn the study the most notable results were found for 14‐3‐3 zeta/delta, beta‐synuclein and the pentraxins. All three pentraxins (1, 2 and the receptor) were decreased compared to controls across all groups, while 14‐3‐3 zeta/delta was increased. Further, beta‐synuclein was seemingly specifically altered (increased) between controls and AD, while no difference was observed between controls and FTLD, and α‐synuclein patients.ConclusionWe have successfully developed a panel of novel CSF biomarkers for synaptic dysfunction. We present results suggesting that several synaptic proteins potentially could be used as biomarkers for synaptic dysfunction and degeneration in not only AD but also other neurodegenerative diseases such as FTLD and α‐synuclein pathologies.