%0 Journal Article %J J Alzheimers Dis %D 2020 %T Dickkopf-1 Overexpression in vitro Nominates Candidate Blood Biomarkers Relating to Alzheimer's Disease Pathology. %A Shi, Liu %A Winchester, Laura M %A Liu, Benjamine Y %A Killick, Richard %A Ribe, Elena M %A Westwood, Sarah %A Baird, Alison L %A Buckley, Noel J %A Hong, Shengjun %A Dobricic, Valerija %A Kilpert, Fabian %A Franke, Andre %A Kiddle, Steven %A Sattlecker, Martina %A Dobson, Richard %A Cuadrado, Antonio %A Hye, Abdul %A Ashton, Nicholas J %A Morgan, Angharad R %A Bos, Isabelle %A Vos, Stephanie J B %A Ten Kate, Mara %A Scheltens, Philip %A Vandenberghe, Rik %A Gabel, Silvy %A Meersmans, Karen %A Engelborghs, Sebastiaan %A De Roeck, Ellen E %A Sleegers, Kristel %A Frisoni, Giovanni B %A Blin, Olivier %A Richardson, Jill C %A Bordet, Régis %A Molinuevo, José L %A Rami, Lorena %A Wallin, Anders %A Kettunen, Petronella %A Tsolaki, Magda %A Verhey, Frans %A Lleo, Alberto %A Alcolea, Daniel %A Popp, Julius %A Peyratout, Gwendoline %A Martínez-Lage, Pablo %A Tainta, Mikel %A Johannsen, Peter %A Teunissen, Charlotte E %A Freund-Levi, Yvonne %A Frölich, Lutz %A Legido-Quigley, Cristina %A Barkhof, Frederik %A Blennow, Kaj %A Rasmussen, Katrine Laura %A Nordestgaard, Børge Grønne %A Frikke-Schmidt, Ruth %A Nielsen, Sune Fallgaard %A Soininen, Hilkka %A Vellas, Bruno %A Kloszewska, Iwona %A Mecocci, Patrizia %A Zetterberg, Henrik %A Morgan, B Paul %A Streffer, Johannes %A Visser, Pieter Jelle %A Bertram, Lars %A Nevado-Holgado, Alejo J %A Lovestone, Simon %X

BACKGROUND: Previous studies suggest that Dickkopf-1 (DKK1), an inhibitor of Wnt signaling, plays a role in amyloid-induced toxicity and hence Alzheimer's disease (AD). However, the effect of DKK1 expression on protein expression, and whether such proteins are altered in disease, is unknown.

OBJECTIVE: We aim to test whether DKK1 induced protein signature obtained in vitro were associated with markers of AD pathology as used in the amyloid/tau/neurodegeneration (ATN) framework as well as with clinical outcomes.

METHODS: We first overexpressed DKK1 in HEK293A cells and quantified 1,128 proteins in cell lysates using aptamer capture arrays (SomaScan) to obtain a protein signature induced by DKK1. We then used the same assay to measure the DKK1-signature proteins in human plasma in two large cohorts, EMIF (n = 785) and ANM (n = 677).

RESULTS: We identified a 100-protein signature induced by DKK1 in vitro. Subsets of proteins, along with age and apolipoprotein E ɛ4 genotype distinguished amyloid pathology (A + T-N-, A+T+N-, A+T-N+, and A+T+N+) from no AD pathology (A-T-N-) with an area under the curve of 0.72, 0.81, 0.88, and 0.85, respectively. Furthermore, we found that some signature proteins (e.g., Complement C3 and albumin) were associated with cognitive score and AD diagnosis in both cohorts.

CONCLUSIONS: Our results add further evidence for a role of DKK regulation of Wnt signaling in AD and suggest that DKK1 induced signature proteins obtained in vitro could reflect theATNframework as well as predict disease severity and progression in vivo.

%B J Alzheimers Dis %V 77 %P 1353-1368 %8 2020 Sep 29 %G eng %N 3 %R 10.3233/JAD-200208 %0 Journal Article %J J Alzheimers Dis %D 2016 %T A Pathway Based Classification Method for Analyzing Gene Expression for Alzheimer's Disease Diagnosis. %A Voyle, Nicola %A Keohane, Aoife %A Newhouse, Stephen %A Lunnon, Katie %A Johnston, Caroline %A Soininen, Hilkka %A Kloszewska, Iwona %A Mecocci, Patrizia %A Tsolaki, Magda %A Vellas, Bruno %A Lovestone, Simon %A Hodges, Angela %A Kiddle, Steven %A Dobson, Richard Jb %K Aged %K Aged, 80 and over %K Alzheimer Disease %K Apolipoproteins E %K Cohort Studies %K Datasets as Topic %K Female %K Gene Expression %K Gene Expression Profiling %K Humans %K Male %K Models, Genetic %K Oligonucleotide Array Sequence Analysis %K Signal Transduction %X

BACKGROUND: Recent studies indicate that gene expression levels in blood may be able to differentiate subjects with Alzheimer's disease (AD) from normal elderly controls and mild cognitively impaired (MCI) subjects. However, there is limited replicability at the single marker level. A pathway-based interpretation of gene expression may prove more robust.

OBJECTIVES: This study aimed to investigate whether a case/control classification model built on pathway level data was more robust than a gene level model and may consequently perform better in test data. The study used two batches of gene expression data from the AddNeuroMed (ANM) and Dementia Case Registry (DCR) cohorts.

METHODS: Our study used Illumina Human HT-12 Expression BeadChips to collect gene expression from blood samples. Random forest modeling with recursive feature elimination was used to predict case/control status. Age and APOE ɛ4 status were used as covariates for all analysis.

RESULTS: Gene and pathway level models performed similarly to each other and to a model based on demographic information only.

CONCLUSIONS: Any potential increase in concordance from the novel pathway level approach used here has not lead to a greater predictive ability in these datasets. However, we have only tested one method for creating pathway level scores. Further, we have been able to benchmark pathways against genes in datasets that had been extensively harmonized. Further work should focus on the use of alternative methods for creating pathway level scores, in particular those that incorporate pathway topology, and the use of an endophenotype based approach.

%B J Alzheimers Dis %V 49 %P 659-69 %8 2016 %G eng %N 3 %1 http://www.ncbi.nlm.nih.gov/pubmed/26484910?dopt=Abstract %R 10.3233/JAD-150440 %0 Journal Article %J J Alzheimers Dis %D 2015 %T Blood Protein Markers of Neocortical Amyloid-β Burden: A Candidate Study Using SOMAscan Technology. %A Voyle, Nicola %A Baker, David %A Burnham, Samantha C %A Covin, Antonia %A Zhang, Zhanpan %A Sangurdekar, Dipen P %A Tan Hehir, Cristina A %A Bazenet, Chantal %A Lovestone, Simon %A Kiddle, Steven %A Dobson, Richard J B %X

BACKGROUND: Four previously reported studies have tested for association of blood proteins with neocortical amyloid-β burden (NAB). If shown to be robust, these proteins could have utility as a blood test for enrichment in clinical trials of Alzheimer's disease (AD) therapeutics.

OBJECTIVE: This study aimed to investigate whether previously identified blood proteins also show evidence for association with NAB in serum samples from the Australian Imaging, Biomarker and Lifestyle Flagship Study of Ageing (AIBL). The study considers candidate proteins seen in cohorts other than AIBL and candidates previously discovered in the AIBL cohort.

METHODS: Our study used the SOMAscan platform for protein quantification in blood serum. Linear and logistic regressions were used to model continuous NAB and dichotomized NAB respectively using single proteins as a predictor. Multiple protein models were built using stepwise regression techniques and support vectors machines. Age and APOE ε4 carriage were used as covariates for all analysis.

RESULTS: Of the 41 proteins previously reported, 15 AIBL candidates and 20 non-AIBL candidates were available for testing. Of these candidates, pancreatic polypeptide (PPY) and IgM showed a significant association with NAB. Notably, IgM was found to associate with continuous NAB across cognitively normal control subjects.

CONCLUSIONS: We have further demonstrated the association of PPY and IgM with NAB, despite technical differences between studies. There are several reasons for a lack of significance for the other candidates including platform differences and the use of serum rather than plasma samples. To investigate the possibility of technical differences causing lack of further replication, further studies are required.

%B J Alzheimers Dis %8 2015 Apr 16 %G eng %R 10.3233/JAD-150020