Background: Amyloid β (Aβ)-directed immunotherapy has shown promising results in preclinical and early clinical
Alzheimer’s disease (AD) trials, but successful translation to late clinics has failed so far. Compelling evidence
suggests that post-translationally modified Aβ peptides might play a decisive role in onset and progression of AD
and first clinical trials targeting such Aβ variants have been initiated. Modified Aβ represents a small fraction of
deposited material in plaques compared to pan-Aβ epitopes, opening up pathways for tailored approaches of
immunotherapy. Here, we generated the first monoclonal antibodies that recognize L-isoaspartate-modified Aβ
(isoD7-Aβ) and tested a lead antibody molecule in 5xFAD mice.
Methods: This work comprises a combination of chemical and biochemical techniques as well as behavioral
analyses. Aβ peptides, containing L-isoaspartate at position 7, were chemically synthesized and used for
immunization of mice and antibody screening methods. Biochemical methods included anti-isoD7-Aβ monoclonal
antibody characterization by surface plasmon resonance, immunohistochemical staining of human and transgenic
mouse brain, and the development and application of isoD7-Aβ ELISA as well as different non-modified Aβ ELISA.
For antibody treatment studies, 12 mg/kg anti-isoD7-Aβ antibody K11_IgG2a was applied intraperitoneally to 5xFAD
mice for 38 weeks. Treatment controls implemented were IgG2a isotype as negative and 3D6_IgG2a, the parent
molecule of bapineuzumab, as positive control antibodies. Behavioral studies included elevated plus maze, pole
test, and Morris water maze.
Results: Our advanced antibody K11 showed a KD in the low nM range and > 400fold selectivity for isoD7-Aβ
compared to other Aβ variants. By using this antibody, we demonstrated that formation of isoD7-Aβ may occur
after formation of aggregates; hence, the presence of the isoD7-modification differentiates aged Aβ from newly
formed peptides. Importantly, we also show that the Tottori mutation responsible for early-onset AD in a Japanese
pedigree is characterized by massively accelerated formation of isoD7-Aβ in cell culture. The presence of isoD7-Aβ
was verified by K11 in post mortem human cortex and 5xFAD mouse brain tissue. Passive immunization of 5xFAD
mice resulted in a significant reduction of isoD7-Aβ and total Aβ in brain. Amelioration of cognitive impairment
was demonstrated by Morris water maze, elevated plus maze, pole, and contextual fear conditioning tests.
Interestingly, despite the lower abundance of the isoD7-Aβ epitope, the application of anti-isoD7-Aβ antibodies
showed comparable treatment efficacy in terms of reduction of brain amyloid and spatial learning but did not
result in an increase of plasma Aβ concentration as observed with 3D6 treatment.
Conclusions: The present study demonstrates, for the first time, that the antibody-mediated targeting of isoD7-
modified Aβ peptides leads to attenuation of AD-like amyloid pathology. In conjunction with previously published
data on antibodies directed against pGlu-modified Aβ, the results highlight the crucial role of modified Aβ peptides
in AD pathophysiology. Hence, the results also underscore the therapeutic potential of targeting modified amyloid
species for defining tailored approaches in AD therapy.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:93866 |
| Date | 26 September 2024 |
| Creators | Gnoth, Kathrin, Piechotta, Anke, Kleinschmidt, Martin, Konrath, Sandra, Schenk, Mathias, Taudte, Nadine, Ramsbeck, Daniel, Rieckmann, Vera, Geissler, Stefanie, Eichentopf, Rico, Barendrecht, Susan, Hartlage-Rübsamen, Maike, Demuth, Hans-Ulrich, Roßner, Steffen, Cynis, Holger, Rahfeld, Jens-Ulrich, Schilling, Stephan |
| Publisher | BioMed Central |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:article, info:eu-repo/semantics/article, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 10.1186/s13195-020-00719-x |
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