N-truncated Aβ4-x peptides in sporadic Alzheimer's disease cases and transgenic Alzheimer mouse models.

Background: The deposition of neurotoxic amyloid-β (Aβ) peptides in plaques in the brain parenchyma and in cerebral blood vessels is considered to be a key event in Alzheimer's disease (AD) pathogenesis. Although the presence and impact of full-length Aβ peptides such as Aβ1-40 and Aβ1-42 have been analyzed extensively, the deposition of N-terminally truncated Aβ peptide species has received much less attention, largely because of the lack of specific antibodies. Methods: This paper describes the generation and characterization of novel antibodies selective for Aβ_4-x peptides and provides immunohistochemical evidence of Aβ_4-x in the human brain and its distribution in the APP/PS1KI and 5XFAD transgenic mouse models. Results: The Aβ_4-x staining pattern was restricted mainly to amyloid plaque cores and cerebral amyloid angiopathy in AD and Down syndrome cases and in both AD mouse models. In contrast, diffuse amyloid deposits were largely negative for Aβ_4-x immunoreactivity. No overt intraneuronal staining was observed. Conclusions: The findings of this study are consistent with previous reports demonstrating a high aggregation propensity of Aβ_4-x peptides and suggest an important role of these N-truncated Aβ species in the process of amyloidogenesis and plaque core formation. [ABSTRACT FROM AUTHOR]