Identification of novel CSF biomarkers for neurodegeneration and their validation by a high-throughput multiplexed targeted proteomic assay

Abstract

BackgroundCurrently there are no effective treatments for many neurodegenerative diseases. Reliable biomarkers for identifying and stratifying these diseases will be important in the development of future novel therapies. Lewy Body Dementia (LBD) is considered an under diagnosed form of dementia for which markers are needed to discriminate LBD from other forms of dementia such as Alzheimer’s Disease (AD). This work describes a Label-Free proteomic profiling analysis of cerebral spinal fluid (CSF) from non-neurodegenerative controls and patients with LBD. Using this technology we identified several potential novel markers for LBD. These were then combined with other biomarkers from previously published studies, to create a 10 min multiplexed targeted and translational MRM-LC-MS/MS assay. This test was used to validate our new assay in a larger cohort of samples including controls and the other neurodegenerative conditions of Alzheimer’s and Parkinson’s disease (PD).ResultsThirty eight proteins showed significantly (p < 0.05) altered expression in LBD CSF by proteomic profiling. The targeted MRM-LC-MS/MS assay revealed 4 proteins that were specific for the identification of AD from LBD: ectonucleotide pyrophosphatase/phosphodiesterase 2 (p < 0.0001), lysosome-associated membrane protein 1 (p < 0.0001), pro-orexin (p < 0.0017) and transthyretin (p < 0.0001). Nineteen proteins were elevated significantly in both AD and LBD versus the control group of which 4 proteins are novel (malate dehydrogenase 1, serum amyloid A4, GM2−activator protein, and prosaposin). Protein-DJ1 was only elevated significantly in the PD group and not in either LBD or AD samples. Correlations with Alzheimer-associated amyloid β-42 levels, determined by ELISA, were observed for transthyretin, GM2 activator protein and IGF2 in the AD disease group (r2 ≥ 0.39, p ≤ 0.012). Cystatin C, ubiquitin and osteopontin showed a strong significant linear relationship (r2 ≥ 0.4, p ≤ 0.03) with phosphorylated–tau levels in all groups, whilst malate dehydrogenase and apolipoprotein E demonstrated a linear relationship with phosphorylated-tau and total-tau levels in only AD and LBD disease groups.ConclusionsUsing proteomics we have identified several potential and novel markers of neurodegeneration and subsequently validated them using a rapid, multiplexed mass spectral test. This targeted proteomic platform can measure common markers of neurodegeneration that correlate with existing diagnostic makers as well as some that have potential to show changes between AD from LBD.Electronic supplementary materialThe online version of this article (doi:10.1186/s13024-015-0059-y) contains supplementary material, which is available to authorized users.

Resveratrol Administration Increases Transthyretin Protein Levels, Ameliorating AD Features: The Importance of Transthyretin Tetrameric Stability

“…More recently, our group has shown that in AD and in mild cognitive impairment (MCI) patients, TTR protein levels are decreased (10) compared with age-matched controls, which is in agreement with a previous observation of lower levels of CSF TTR in AD patients (11). Moreover, TTR levels in the CSF were found to be negatively correlated with formation of senile plaques (12) and disease progression (13), and positively correlated with Aβ 42 CSF levels in AD patients (14). Thus it is hypothesized that before Aβ deposition, diminishment of TTR is responsible for increased levels of Aβ 42 , consequently promoting its deposition, and finally, with disease establishment, CSF Aβ 42 levels decrease due to sequestration in senile plaques.…”

A Consensus Proteomic Analysis of Alzheimer’s Disease Brain and Cerebrospinal Fluid Reveals Early Changes in Energy Metabolism Associated with Microglia and Astrocyte Activation

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