Small peptide fingerprint (peptidomics) of Amyotrophic Lateral Sclerosis in CSF

Background Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by abnormal protein aggregates in motor neurons. Present and earlier proteomic studies to characterize peptides in cerebrospinal fluid (CSF) associated with motoneuron pathology did not target the low molecular weight proteins and peptides. We generated the hypothesis that specific changes in CSF peptides or low molecular weight proteins are significantly changed in ALS, and that these changes may support deciphering molecular pathophysiology and even guide approaches towards therapeutic interventions. Methods Cerebrospinal fluid (CSF) from 50 ALS patients and 50 non-ALS controls was collected, centrifuged immediately after collection, aliquoted into polypropylene test tubes, frozen within 30–40 min after the puncture and stored at −80°C until use. Peptides were sequenced using capillary electrophoresis or liquid chromatography / mass spectrometry (CE-MS/MS or LC-MS/MS) analyses. Findings In cerebrospinal CSF from 50 patients and 50 non-ALS controls 33 peptides were found, of which 14 could be sequenced using a non-lytic single pot proteomic detection method, CE/MS. ALS deregulated peptides vs. controls included Integral membrane protein 2B, Neurosecretory protein VGF, Osteopontin, Neuroendocrine protein 7B2 (Secretogranin-V), EGF-containing fibulin-like extracellular matrix protein 1, Xylosyltransferase 1 XT-1, Chromogranin-A, Superoxide dismutase SOD-1, Secretogranin-1 (Chromogranin B), NR2F2 Nuclear Receptor Subfamily 2 Group F Member 2 and Collagen alpha-1(VII) chain. Interpretation Most striking deregulations in CSF from ALS patients were found in VGF, Osteopontin, SOD-1 and EFEMP1 peptides. No associations of disease severity, duration and region of onset with sequenced peptides were found. Declarations of Interest S. Petri received honoraria as speaker/consultant from Biogen GmbH, Roche, Novartis, Teva, Cytokinetics Inc., Desitin, Italfarmaco, Ferrer, Amylyx, and Zambon; and grants from DGM e.V, Federal Ministry of Education and Research, German Israeli Foundation for Scientific Research and Development, EU Joint Program for Neurodegenerative Disease Research. J. Beige received funding from GSK and German Federal Ministries of Research and Health. Funding There was no funding to the presented investigation Ethical Approval This study was approved by the ethics committee of Hannover Medical School. Written informed consent was obtained from all participants in accordance with the Declaration of Helsinki. Key words: ALS, CSF, proteomics, biomarker, peptidomics, peptide deregulation