Premium
P1‐126: Investigating Alzheimer's disease in the blood cellular fraction
Author(s) -
Watt Andrew,
Perez Keyla,
Rowe Christopher,
Villemagne Victor,
Masters Colin,
Barnham Kevin,
Faux Noel,
Pike Kerryn
Publication year - 2011
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2011.05.406
Subject(s) - disease , alzheimer's disease , pathogenesis , medicine , chemistry
shown this protein panel to have potential for the diagnosis of Alzheimer’s disease (AD). Hence, the developed SRM assay was used to confirm statistically significant differences in the CSF of AD patients (n 1⁄4 20) as compared to non-demented controls (NDCs; n 1⁄4 20). Methods: CSF samples were reduced, alkylated, digested with trypsin and purified. An in silico approach was used to select tryptic peptides representative of each candidate biomarker. To select suitable peptides for quantitation, an intelligent SRM method was developed. Analysis was performed on a Surveyor LC system coupled to a TSQ Vantage mass spectrometer. Three peptides per protein were selected and synthesised as heavy-labeled internal standards. Data was analysed using Pinpoint. Quantitation of each peptide was compared between groups using Prism. Results: When taking the best peptide of B2M, all SRM transitions had strong sensitivities across all samples and followed the same pattern. Inline with discovery, a statistically significant (p-value < 0.0001) increase was observed in AD, compared to NDCs. The two remaining peptides had high variance, suspected to be due to poor sensitivities and being below the limits of detection/quantitation. VGF: Using the best peptide of VGF, a statistically significant (p-value 1⁄4 0.0419) increase was observed in AD subjects as compared to NDCs. This contradicted discovery. However, discovery observations were based on a fragment of VGF and here, based on a proteotypic signature-peptide of this protein fragment, thus measuring both the VGF fragment and total protein. This may explain the discrepancy in results. The remaining VGF peptides had poor endogenous detection in CSF. Cystatin-C: All signature-peptides of this protein were reliably detected across all samples. The best cystatin-C peptide had a statistically significant (p-value1⁄4 0.0033) reduction in AD compared to NDCs. This contradicted the original discovery study, but cystatin-C was subsequently been shown to be decreased in AD CSF. Conclusions: Application of the SRM assay supports the initial discovery of B2M, VGF, and cystatin-C as potential CSF biomarkers of AD.