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Duchateau L, Küҫükali F, De Roeck A, Wittens MMJ, Temmerman J, Weets I, Timmers M, Engelborghs S, Bjerke M, Sleegers K. CSF biomarker analysis of ABCA7 mutation carriers suggests altered APP processing and reduced inflammatory response. Alzheimers Res Ther 2023; 15:195. [PMID: 37946268 PMCID: PMC10634183 DOI: 10.1186/s13195-023-01338-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 10/24/2023] [Indexed: 11/12/2023]
Abstract
BACKGROUND The Alzheimer's disease (AD) risk gene ABCA7 has suggested functions in lipid metabolism and the immune system. Rare premature termination codon (PTC) mutations and an expansion of a variable number of tandem repeats (VNTR) polymorphism in the gene, both likely cause a lower ABCA7 expression and hereby increased risk for AD. However, the exact mechanism of action remains unclear. By studying CSF biomarkers reflecting different types of AD-related pathological processes, we aim to get a better insight in those processes and establish a biomarker profile of mutation carriers. METHODS The study population consisted of 229 AD patients for whom CSF was available and ABCA7 sequencing and VNTR genotyping had been performed. This included 28 PTC mutation and 16 pathogenic expansion carriers. CSF levels of Aβ1-42, Aβ1-40, P-tau181, T-tau, sAPPα, sAPPβ, YKL-40, and hFABP were determined using ELISA and Meso Scale Discovery assays. We compared differences in levels of these biomarkers and the Aβ ratio between AD patients with or without an ABCA7 PTC mutation or expansion using linear regression on INT-transformed data with APOE-status, age and sex as covariates. RESULTS Carriers of ABCA7 expansion mutations had significantly lower Aβ1-42 levels (P = 0.022) compared with non-carrier patients. The effect of the presence of ABCA7 mutations on CSF levels was especially pronounced in APOE ε4-negative carriers. In addition, VNTR expansion carriers had reduced Aβ1-40 (P = 0.023), sAPPα (P = 0.047), sAPPβ (P = 0.016), and YKL-40 (P = 0.0036) levels. CONCLUSIONS Our results are suggestive for an effect on APP processing by repeat expansions given the changes in the amyloid-related CSF biomarkers that were found in carriers. The decrease in YKL-40 levels in expansion carriers moreover suggests that these patients potentially have a reduced inflammatory response to AD damage. Moreover, our findings suggest the existence of a mechanism, independent of lowered expression, affecting neuropathology in expansion carriers.
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Affiliation(s)
- Lena Duchateau
- Complex Genetics of Alzheimer's Disease Group, VIB-UAntwerp Center for Molecular Neurology, VIB, Building V, Universiteitsplein 1, Wilrijk, Antwerp, B-2610, Belgium
- Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Antwerp, 2610, Belgium
| | - Fahri Küҫükali
- Complex Genetics of Alzheimer's Disease Group, VIB-UAntwerp Center for Molecular Neurology, VIB, Building V, Universiteitsplein 1, Wilrijk, Antwerp, B-2610, Belgium
- Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Antwerp, 2610, Belgium
| | - Arne De Roeck
- Complex Genetics of Alzheimer's Disease Group, VIB-UAntwerp Center for Molecular Neurology, VIB, Building V, Universiteitsplein 1, Wilrijk, Antwerp, B-2610, Belgium
- Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Antwerp, 2610, Belgium
- Present Address: Argenx, Ghent, Belgium
| | - Mandy M J Wittens
- Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Antwerp, 2610, Belgium
- Clinical Neurochemistry Laboratory, Department of Clinical Biology, University Hospital Brussels, Generaal Jacqueslaan 137, Elsene, Brussels, 1050, Belgium
| | - Joke Temmerman
- Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Antwerp, 2610, Belgium
- Neuroprotection & Neuromodulation (NEUR) Research Group, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, Jette, Brussels, 1090, Belgium
| | - Ilse Weets
- Clinical Neurochemistry Laboratory, Department of Clinical Biology, University Hospital Brussels, Generaal Jacqueslaan 137, Elsene, Brussels, 1050, Belgium
- Experimental Pharmacology (EFAR) Research Group, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, Brussels, 1090, Belgium
| | - Maarten Timmers
- Reference Center for Biological Markers of Dementia, Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Antwerp, 2610, Belgium
- Janssen Research and Development, a Division of Janssen Pharmaceutica NV, Turnhoutseweg 30, Beerse, 2340, Belgium
| | - Sebastiaan Engelborghs
- Neuroprotection & Neuromodulation (NEUR) Research Group, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, Jette, Brussels, 1090, Belgium
- Reference Center for Biological Markers of Dementia, Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Antwerp, 2610, Belgium
- Department of Neurology and Bru-BRAIN, University Hospital Brussels, Generaal Jacqueslaan 137, Elsene, Brussels, 1050, Belgium
| | - Maria Bjerke
- Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Antwerp, 2610, Belgium
- Clinical Neurochemistry Laboratory, Department of Clinical Biology, University Hospital Brussels, Generaal Jacqueslaan 137, Elsene, Brussels, 1050, Belgium
- Neuroprotection & Neuromodulation (NEUR) Research Group, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, Jette, Brussels, 1090, Belgium
| | - Kristel Sleegers
- Complex Genetics of Alzheimer's Disease Group, VIB-UAntwerp Center for Molecular Neurology, VIB, Building V, Universiteitsplein 1, Wilrijk, Antwerp, B-2610, Belgium.
- Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Antwerp, 2610, Belgium.
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