Absolute quantitation of plasma surrogate biomarker APL1β peptides for Alzheimer disease

Takeshi Tomonaga¹⁾, Seizo Sano¹⁾, Shio Watanabe¹⁾, Kumiko Yoshizawa-Kumagaye²⁾, Masahiko Tsunemi²⁾, Shinji Tagami³⁾, Masayasu Okochi³⁾, Masatoshi Takeda³)

¹⁾Laboratory of Proteome Research, National Institute of Biomedical Innovation
²⁾Peptide Institute, Inc
³⁾Psychiatry, Department of Integrated Medicine, Division of Internal Medicine, Osaka University Graduate School of Medicine

Recent advances in proteomic technology such as selected/multiple reaction monitoring (SRM/MRM) enabled the detection and quantification of specific proteins in complex samples.We have previously identified APLP1-derived Aβ-like peptides (APL1β 25, 27, 28) in human cerebrospinal fluid (CSF) and found that the ratio of APL1β28/ total APL1β increases in CSF of Alzheimer disease (AD) patients compared with non-AD controls, which could be a novel surrogate marker for AD.Here, we investigated if APL1β could be detected and quantified in human plasma with SRM/MRM.Owing to improvement of method for plasma pretreatment, we succeeded in quantitate plasma APL1β peptides.Strikingly, plasma APL1β concentrations were at fmol/ml level and were more than thousand times lower than those in CSF.

Address correspondence to Dr. Takeshi Tomonaga, Laboratory of Proteome Research, National Institute of Biomedical Innovation (7-6-8 Saito Asagi, Ibaraki-shi, Osaka 567-0085, Japan)