Comparative peptidome analyses of the profiles of the peptides ranging from 1–10 KD in CSF samples pooled from probable sporadic CJD and non-CJD patients

The shotgun strategy applying tandem mass spectrometry has been widely used to identify the proteins that are differentially distributed among diseases for its high reliability and efficiency. To find out the potential difference of protein profiles in cerebrospinal fluids (CSF) between Creutzfeldt-Jakob disease (CJD) and non-CJD patients, especially in the fraction ranging from 1-10 KD, the CSF samples of 40 probable sporadic CJD (sCJD) patients, 32 non-CJD cases with dementia and 17 non-CJD cases without dementia were separately pooled and enriched by the magnetic beads based weak cation exchange chromatography (MB-WCX). After trypsin digestion, each enriched CSF was separated and identified by RP-HPLC-ESI-QTOF MS/MS. In total, 42, 53 and 47 signals of proteins were identified in the pooled CSF fraction less than 10 KD of probable sCJD, non-CJD with dementia and non-CJD without dementia, respectively. Compared with that of probable sCJD, the similarity of CSF protein profiles of non-CJD with dementia (76.2%) were higher than that of non-CJD without dementia (57.1%). Nine CSF proteins were found to be specially observed in probable sCJD group. Those data may help to select the potential biomarkers for diagnosis of CJD. Additionally, further studies of the small segments of cellular proteins in CSF of CJD patients may also provide scientific clues for understanding the neuropathogenesis of TSEs.