A new sandwich immunoassay for detection of the α-secretase cleaved, soluble amyloid-β protein precursor in cerebrospinal fluid and serum.
Alzheimer's disease (AD) is the most common neurodegenerative disorder. Frequently used diagnostic biomarkers are amyloid-β42 (Aβ42), tau, and phospho-tau, which are measured in cerebrospinal fluid (CSF), and allow a reasonable, but not full, separation of AD patients and controls. Besides Aβ42, additional proteolytic cleavage products of the amyloid-β protein precursor (AβPP) have been investigated as potential biomarkers. This includes the α-secretase cleaved soluble AβPP ectodomain (sAβPPα). However, some studies found a reduction of sAβPPα, whereas other studies reported an increase of sAβPPα in the CSF of AD patients. The divergent findings may result from the detection of sAβPPα with antibodies, such as 6E10, which do not exclusively detect sAβPPα, but also the alternative β-secretase cleavage product sAβPPβ'. Here, we used the sAβPPα-specific antibody 14D6 and developed an ELISA-like sandwich immunoassay. The assay specifically detected sAβPPα in cell culture supernatants, in human CSF and even in serum, which is more readily accessible than CSF. The assay was used to analyze sAβPPα levels in CSF and serum of AD patients and controls. The assay detected a mild, but significant increase in sAβPPα in the CSF of AD patients compared to non-demented controls, while a mild reduction was observed in serum. The 14D6 assay in CSF allowed a better separation of AD patients from controls compared to the 6E10 antibody. Taken together, the new assay is widely applicable for specific sAβPPα measurement in culture media, CSF, and serum.
DZNE - German Center for Neurodegenerative Diseases, Munich, Germany Neuroproteomics, Klinikum rechts der Isar Technische Universität München, Munich, Germany.
Mara
M
Taverna
Tobias
T
Straub
Harald
H
Hampel
Dan
D
Rujescu
Stefan F
SF
Lichtenthaler
D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases / Q000097:blood* / Q000134:cerebrospinal fluid* / Q000235:genetics; D016564:Amyloid beta-Protein Precursor / Q000097:blood* / Q000134:cerebrospinal fluid* / Q000235:genetics; D015415:Biomarkers / Q000097:blood / Q000134:cerebrospinal fluid; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay / Q000639:trends; D005260:Female; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D012042:Registries
D016564:Amyloid beta-Protein Precursor; D015415:Biomarkers; D053829:Amyloid Precursor Protein Secretases
Alzheimer's disease; amyloid-β protein precursor; biomarker; sandwich immunoassay; α-Secretase