Mitochondrial Proteins as Parkinson’s Disease Circulatory Biomarkers – a Translational Study Sandra Anjo (Presenter) University of Coimbra (CNC-UC) >> POSTER (PDF) Presenter Bio: I have a PhD degree in Biosciences from the University of Coimbra. Since April 2017, I am a postdoc fellow in a project devoted to biomarker discovery in diseases that have synaptic dysfunction as a common denominator. I have been working in the neuroscience field since my masters, using interactomics and quantitative mass spectrometry (MS) to clarify the mechanisms of action of a PD-related protein. During my PhD, I further extended my interests to a more applied field, resulting in the implementation of an innovative biomarkers discovery method and preliminary data on the identification of secreted oxidative stress and cell death biomarkers using cells and animal models. My current research interests are: i) quantitative mass spectrometry applied to neuroproteomics, interatomics, and biomarker discovery and ii) oxidative Stress impact in neurodegeneration & neurodegenerative disorders.

Authors: Sandra I. Anjo (1, 2), Patrícia Valério dos Santos (3), Maria Luiza Constante Rosado (4, 5), Graça Baltazar (4), Mário Grãos (1, 6), Bruno Manadas (1
(1) Center for Neuroscience and Cell Biology, UC, Coimbra, Portugal; (2) Faculty of Medicine, UC, Coimbra, Portugal; (3) Centro Hospitalar de Setúbal, Setúbal, Portugal; (4) Faculty of Health Sciences, UBI, Covilhã, Portugal; (5) Centro Hospitalar Cova da Beira, E.P.E., Covilhã, Portugal; (6) Biocant, Biotechnology Transfer Association, Cantanhede, Portugal

Using a translational approach (from cells secretome to plasma samples), we could identify two mitochondria-related proteins in plasma samples, which in combination lead to a powerful model with potential diagnostic value to discriminate the PD patients from matched. The analysis of secretomes from cells cultured under control or oxidative stress conditions, reveals several mitochondria-related proteins released in higher amounts under oxidative stress. This screening, performed by SWATH-MS, was translated to plasma samples from 28 control and 31 PD patients, and two of these proteins were found to be significantly changed. These proteins are associated with apoptotic mitochondrial changes, which may correspond to potential indicators of cell death and have never been reported as blood biomarkers for PD.

Introduction

The identification of circulating biomarkers that closely correlate with PD has failed several times in the past. Nevertheless, using a translational approach we could monitor two mitochondria-related proteins in plasma samples, which in combination lead to a powerful model with potential diagnostic value to discriminate the PD patients from matched controls.

Methods

This translational approach was initiated by the analysis of secretomes from cells cultured under control or oxidative stress conditions, from which several mitochondria-related proteins were found to be released in higher amounts under oxidative stress. This screening, performed by SWATH-MS, was translated to the analysis of plasma samples from 28 control and 31 PD patients, and two of these proteins were found to be significantly changed in PD cohort.

Results

A linear discriminant analysis of the results obtained for these two proteins originates a model with potential diagnostic value to discriminate PD patients. The model obtained has a specificity of 77.4%, a sensitivity of 78.6%; cross-validation of 76.3% and a ROC analysis with an area under the curve (AUC) of 0.872.

Conclusions & Discussion

These two proteins are associated with apoptotic mitochondrial changes, which may correspond to potential indicators of cell death and have never been reported as blood biomarkers for PD. In fact, to the best of our knowledge, one of these proteins was identified in plasma samples for the first time, and the other protein was already reported to be altered in as Alzheimer’s patients but not in PD patients. In this sense, we believe that the novelty and success of our results arise from the combination of: i) a translational research pipeline, where plasma samples were interrogated with previous knowledge from cell secretome under oxidative stress, and ii) the use of the quantification approach SWATH-MS associated with the use of a biofluid optimized normalization method.

This work was financed by the European Regional Development Fund (ERDF) through the COMPETE 2020 - Operational Programme for Competitiveness and Internationalisation and Portuguese national funds via FCT – Fundação para a Ciência e a Tecnologia, I.P., under projects: POCI-01-0145-FEDER-007440 (ref.: UID/NEU/04539/2013), POCI-01-0145-FEDER-016428 (ref.:SAICTPAC/0010/2015), and POCI-01-0145-FEDER-016795 (ref.: PTDC/NEU-SCC/7051/2014); and by The National Mass Spectrometry Network (RNEM) under the contract LISBOA-01-0145-FEDER-402-022125 (ref.: ROTEIRO/0028/2013).