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APLP1 as a cerebrospinal fluid biomarker for ?-secretase modulator treatment.

ABSTRACT: Alzheimer's disease brains are characterized by extracellular plaques containing the aggregated amyloid ?42 (A?42) peptide and intraneuronal tangles containing hyperphosphorylated tau. A?42 is produced by sequential processing of the amyloid precursor protein (APP) by ?-secretase followed by ?-secretase. Substantial efforts have been put into developing pharmaceuticals preventing the production or increasing the clearance of A?42. However, treatments inhibiting ?-secretase have proven disappointing due to off-target effects. To circumvent these effects, ?-secretase modulators (GSMs) have been developed, which rather than inhibiting ?-secretase shift its preference into producing less aggregation-prone shorter A? peptides. Belonging to the same family of proteins as APP, amyloid-like protein 1 (APLP1) is also a substrate for ?-secretase. Herein we investigated whether the GSM E2012 affects APLP1 processing in the central nervous system by measuring APLP1 peptide levels in cerebrospinal fluid (CSF) before and after E2012 treatment in dogs.An in-house monoclonal APLP1 antibody, AP1, was produced and utilized for immunopurification of APLP1 from human and dog CSF in a hybrid immuno-affinity mass spectrometric method. Seven dogs received a single dose of 20 or 80 mg/kg of E2012 in a randomized cross-over design and CSF was collected prior to and 4, 8 and 24 hours after dosing.We have identified 14 CSF APLP1 peptides in humans and 12 CSF APLP1 peptides in dogs. Of these, seven were reproducibly detectable in dogs who received E2012. We found a dose-dependent relative increase of the CSF peptides APLP1?17, 1?18 and 1?28 accompanied with a decrease of 1?25 and 1?27 in response to E2012 treatment. All peptides reverted to baseline over the time of sample collection.We show an in vivo effect of the GSM E2012 on the processing of APLP1 which is measurable in CSF. These data suggest that APLP1 peptides may be used as biomarkers to monitor drug effects of GSMs on ?-secretase processing in clinical trials. However, this requires further investigation in larger cohorts, including studies in man.

SUBMITTER: Sjodin S

PROVIDER: S-EPMC4687145 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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APLP1 as a cerebrospinal fluid biomarker for γ-secretase modulator treatment.

Sjödin Simon S Andersson Kerstin K A KK Mercken Marc M Zetterberg Henrik H Borghys Herman H Blennow Kaj K Portelius Erik E

Alzheimer's research & therapy 20151222 1

<h4>Introduction</h4>Alzheimer's disease brains are characterized by extracellular plaques containing the aggregated amyloid β42 (Aβ42) peptide and intraneuronal tangles containing hyperphosphorylated tau. Aβ42 is produced by sequential processing of the amyloid precursor protein (APP) by β-secretase followed by γ-secretase. Substantial efforts have been put into developing pharmaceuticals preventing the production or increasing the clearance of Aβ42. However, treatments inhibiting γ-secretase h ...[more]

PMID: 26689589

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Project description:In a large multicentre sample of cognitively normal subjects, as a function of age, gender and APOE genotype, we studied the frequency of abnormal cerebrospinal fluid levels of Alzheimer's disease biomarkers including: total tau, phosphorylated tau and amyloid-β1-42. Fifteen cohorts from 12 different centres with either enzyme-linked immunosorbent assays or Luminex® measurements were selected for this study. Each centre sent nine new cerebrospinal fluid aliquots that were used to measure total tau, phosphorylated tau and amyloid-β1-42 in the Gothenburg laboratory. Seven centres showed a high correlation with the new Gothenburg measurements; therefore, 10 cohorts from these centres are included in the analyses here (1233 healthy control subjects, 40-84 years old). Amyloid-β amyloid status (negative or positive) and neurodegeneration status (negative or positive) was established based on the pathological cerebrospinal fluid Alzheimer's disease cut-off values for cerebrospinal fluid amyloid-β1-42 and total tau, respectively. While gender did not affect these biomarker values, APOE genotype modified the age-associated changes in cerebrospinal fluid biomarkers such that APOE ε4 carriers showed stronger age-related changes in cerebrospinal fluid phosphorylated tau, total tau and amyloid-β1-42 values and APOE ε2 carriers showed the opposite effect. At 40 years of age, 76% of the subjects were classified as amyloid negative, neurodegeneration negative and their frequency decreased to 32% at 85 years. The amyloid-positive neurodegeneration-negative group remained stable. The amyloid-negative neurodegeneration-positive group frequency increased slowly from 1% at 44 years to 16% at 85 years, but its frequency was not affected by APOE genotype. The amyloid-positive neurodegeneration-positive frequency increased from 1% at 53 years to 28% at 85 years. Abnormally low cerebrospinal fluid amyloid-β1-42 levels were already frequent in midlife and APOE genotype strongly affects the levels of cerebrospinal fluid amyloid-β1-42, phosphorylated tau and total tau across the lifespan without influencing the frequency of subjects with suspected non-amyloid pathology.

Project description:The goal of this study is to investigate the value of tau phosphorylated at threonine 181 (P-tau181P) in the Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarker panel for differential dementia diagnosis in autopsy confirmed AD and non-AD patients. The study population consisted of 140 autopsy confirmed AD and 77 autopsy confirmed non-AD dementia patients. CSF concentrations of amyloid-? peptide of 42 amino acids (A?1-42), total tau protein (T-tau), and P-tau181P were determined with single analyte ELISA-kits (INNOTEST(®), Fujirebio, Ghent, Belgium). Diagnostic accuracy was assessed through receiver operating characteristic (ROC) curve analyses to obtain area under the curve (AUC) values and to define optimal cutoff values to discriminate AD from pooled and individual non-AD groups. ROC curve analyses were only performed on biomarkers and ratios that differed significantly between the groups. Pairwise comparison of AUC values was performed by means of DeLong tests. The A?1-42/P-tau181P ratio (AUC?=?0.770) performed significantly better than A?1-42 (AUC?=?0.677, P?=?0.004), T-tau (AUC?=?0.592, P?<?0.001), and A?1-42/T-tau (AUC?=?0.678, P?=?0.001), while P-tau181P (AUC?=?0.720) performed significantly better than T-tau (AUC?=?0.592, P?<?0.001) to discriminate between AD and the pooled non-AD group. When comparing AD and the individual non-AD diagnoses, A?1-42/P-tau181P (AUC?=?0.894) discriminated AD from frontotemporal dementia significantly better than A?1-42 (AUC?=?0.776, P?=?0.020) and T-tau (AUC?=?0.746, P?=?0.004), while P-tau181P/T-tau (AUC?=?0.958) significantly improved the differentiation between AD and Creutzfeldt-Jakob disease as compared to A?1-42 (AUC?=?0.688, P?=?0.004), T-tau (AUC?=?0.874, P?=?0.040), and A?1-42/P-tau181P (AUC?=?0.760, P?=?0.003). In conclusion, this study demonstrates P-tau181P is an essential component of the AD CSF biomarker panel, and combined assessment of A?1-42, T-tau, and P-tau181P renders, to present date, the highest diagnostic power to discriminate between AD and non-AD dementias.

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APLP1 as a cerebrospinal fluid biomarker for ?-secretase modulator treatment.

Publications

APLP1 as a cerebrospinal fluid biomarker for γ-secretase modulator treatment.

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