Abstract
Background: Recent efforts have described an immunogenic component to the pathobiology of Alzheimer's disease (AD) and Parkinson's disease (PD). However, current methods of studying fluid autoantibodies, such as enzyme-linked immunosorbent assays and immunohistochemistry, are hypothesis-driven and not optimal for discovering new autoantibody biomarkers by proteome-wide screening. Recently, we developed a general mass spectrometry-based approach to identify tissue-specific autoantibodies in serum, at a proteome-wide level. In this study, we adapted the method to explore novel autoantibody biomarkers in the cerebrospinal fluid (CSF) of AD and PD patients. Methods: CSF samples were obtained from 10 headache control individuals, 10 AD patients and 10 PD patients. Antibodies present in the CSF were isolated by immobilization to protein-G magnetic beads. These antibodies were incubated with a brain tissue extract, prepared from frontal cortex, pons, cerebellum and brain stem. Protein antigens captured by the protein-G magnetic bead-bound antibodies were digested with trypsin and analyzed using mass spectrometry. Autoantibody candidates were selected by 1) detection in one or less individuals of the control group and 2) identification in at least half of the patient groups. Results: There were 16 putative autoantibody biomarkers selected from the AD group. Glia-derived nexin autoantibody was detected in eight of ten AD patients and was absent in the control group. Other AD pathology-related targets were also identified, such as actin-interaction protein, quinone oxidoreductase, sushi repeat-containing protein, metalloproteinase inhibitor 2, IP3 receptor 1 and sarcoplasmic/endoplasmic reticulum calcium ATPase 2. An additional eleven autoantibody targets were also identified in the present experiment, although their link to AD is not clear. No autoantibodies in the PD group satisfied our selection criteria. Conclusion: Our unbiased mass spectrometry method was able to detect new putative CSF autoantibody biomarkers of AD. Further investigation into the involvement of humoral autoimmunity in AD and PD pathobiology may be warranted.
Highlights
Significant efforts have been made on advancing diagnostic protein biomarkers of Alzheimer’s (AD) and Parkinson’s (PD) disease, the most common forms of neurodegenerative diseases
Clinical diagnosis of Parkinson’s disease (PD) was made based on the modified Hoehn and Yahr (H-Y) scale13
Age was significantly different between groups (p = 0.0002), and pairwise comparisons revealed lower age in the control group than both Alzheimer’s disease (AD) (p = 0.0005) and PD (p = 0.0025) patient groups
Summary
Significant efforts have been made on advancing diagnostic protein biomarkers of Alzheimer’s (AD) and Parkinson’s (PD) disease, the most common forms of neurodegenerative diseases. These discoveries inform the underlying pathobiology and innovative therapeutics for AD and PD1,2. Changes in brain-related autoantibody levels in CSF and serum of AD and PD patients have been identified. We developed a general mass spectrometrybased approach to identify tissue-specific autoantibodies in serum, at a proteome-wide level. We adapted the method to explore novel autoantibody biomarkers in the cerebrospinal fluid (CSF) of AD and PD patients. Antibodies present in the CSF were isolated by immobilization to protein-G magnetic beads.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
