title: Observations in APP bitransgenic mice suggest that diffuse and compact plaques form via independent processes in Alzheimer's disease.
abstract: Studies of familial Alzheimer's disease suggest that misfolding and aggregation of amyloid-β (Aβ) peptides initiate the pathogenesis. The Arctic mutation of Aβ precursor protein (APP) results in AD, and Arctic Aβ is more prone to form Aβ protofibrils and extracellular deposits. Herein is demonstrated that the burden of diffuse Aβ deposits but not compact plaques is increased when tg-Swe mice are crossed with tg-ArcSwe mice synthesizing low levels of Arctic Aβ. The diffuse deposits in bitransgenic mice, which contain primarily wild-type Aβ42, accumulate in regions both with and without transgene expression. However, APP processing, when compared with tg-Swe, remains unchanged in young bitransgenic mice, whereas wild-type Aβ42 aggregation is accelerated and fibril architecture is altered in vitro and in vivo when a low level of Arctic Aβ42 is introduced. Thus, the increased number of diffuse deposits is likely due to physical interactions between Arctic Aβ and wild-type Aβ42. The selective increase of a single type of parenchymal Aβ deposit suggests that different pathways lead to formation of diffuse and compact plaques. These findings could have general implications for Alzheimer's disease pathogenesis and particular relevance to patients heterozygous for the Arctic APP mutation. Moreover, it further illustrates how Aβ neuropathologic features can be manipulated in vivo by mechanisms similar to those originally conceptualized in prion research.
authors.affiliation: Department of Public Health and Caring Sciences/Molecular Geriatrics, Uppsala University, Uppsala, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Lord
authors.forename: Ola
authors.initials: O
authors.lastname: Philipson
authors.forename: Therése
authors.initials: T
authors.lastname: Klingstedt
authors.forename: Gunilla
authors.initials: G
authors.lastname: Westermark
authors.forename: Per
authors.initials: P
authors.lastname: Hammarström
authors.forename: K Peter R
authors.initials: KP
authors.lastname: Nilsson
authors.forename: Lars N G
authors.initials: LN
authors.lastname: Nilsson
mesh_terms: D000544:Alzheimer Disease / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D046529:Microscopy, Electron, Transmission; D058225:Plaque, Amyloid / Q000473:pathology*
chemical_list: D016564:Amyloid beta-Protein Precursor