Exacerbation of cerebral amyloid angiopathy-associated microhemorrhage in amyloid precursor protein transgenic mice by immunotherapy is dependent on antibody recognition of deposited forms of amyloid beta
Margaret M Racke, Laura I Boone, Deena L Hepburn, Maia Parsadainian, Matthew T Bryan, Daniel K Ness, Kathy S Piroozi, William H Jordan, Donna D Brown, Wherly P Hoffman, David M Holtzman, Kelly R Bales, Bruce D Gitter, Patrick C May, Steven M Paul, Ronald B DeMattos, Margaret M Racke, Laura I Boone, Deena L Hepburn, Maia Parsadainian, Matthew T Bryan, Daniel K Ness, Kathy S Piroozi, William H Jordan, Donna D Brown, Wherly P Hoffman, David M Holtzman, Kelly R Bales, Bruce D Gitter, Patrick C May, Steven M Paul, Ronald B DeMattos
Abstract
Passive immunization with an antibody directed against the N terminus of amyloid beta (Abeta) has recently been reported to exacerbate cerebral amyloid angiopathy (CAA)-related microhemorrhage in a transgenic animal model. Although the mechanism responsible for the deleterious interaction is unclear, a direct binding event may be required. We characterized the binding properties of several monoclonal anti-Abeta antibodies to deposited Abeta in brain parenchyma and CAA. Biochemical analyses demonstrated that the 3D6 and 10D5, two N-terminally directed antibodies, bound with high affinity to deposited forms of Abeta, whereas 266, a central domain antibody, lacked affinity for deposited Abeta. To determine whether 266 or 3D6 would exacerbate CAA-associated microhemorrhage, we treated aged PDAPP mice with either antibody for 6 weeks. We observed an increase in both the incidence and severity of CAA-associated microhemorrhage when PDAPP transgenic mice were treated with the N-terminally directed 3D6 antibody, whereas mice treated with 266 were unaffected. These results may have important implications for future immune-based therapeutic strategies for Alzheimer's disease.
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Source: PubMed