title: Vessel ultrastructure in APP23 transgenic mice after passive anti-Abeta immunotherapy and subsequent intracerebral hemorrhage.
abstract: Passive immunization of amyloid precursor protein (APP) transgenic mice with anti-amyloid beta (Abeta) antibodies was shown to reduce Abeta-deposition in brain and to improve cognition. However, immunotherapy may also be accompanied by a significant increase in the frequency of intracerebral hemorrhages. Because hemorrhages are associated with amyloid-laden vessels, this raises the question whether high concentrations of anti-Abeta antibodies may directly or indirectly lead to a structural destabilization of the vessel wall. To address this point, transmission electron microscopy was performed and the ultrastructure of bleeding and non-bleeding vessels in immunized and non-immunized APP23 transgenic animals was analyzed. To localize bleeding vessels, hemosiderin-positive macrophages were visualized by pre-embedding Perl's Berlin Blue histochemistry. Vessels were analyzed morphologically, anomalies evaluated and quantified. Bleeding vessels were, furthermore, reconstructed in three dimensions to analyze the spatial distribution of amyloid deposits and other pathological changes of the vessel wall. This in-depth morphological analysis revealed that bleeding vessels in immunized as well as in non-immunized APP23 mice were surrounded by a higher number of macrophages compared to non-bleeding vessels in the same animals. However, no differences in the number of macrophages or other structural parameters, such as amyloid deposition, were observed between bleeding vessels of immunized and non-immunized mice. No pathologies which may indicate impending bleeding were observed in the vascular wall of non-bleeding vessels. We conclude, that the increased hemorrhage frequency observed after passive immunization with anti-Abeta antibodies does not lead to overt structural changes in the vessel wall of APP23 transgenic mice. Minor structural alterations of the vessel wall, however, cannot be excluded due to the sample size of our study and the high complexity of the three-dimensional vessel wall ultrastructure.
authors.affiliation: Institute of Clinical Neuroanatomy, J. W. Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt, Germany.
authors.forename: Guido J
authors.initials: GJ
authors.lastname: Burbach
authors.forename: Andreas
authors.initials: A
authors.lastname: Vlachos
authors.forename: Estifanos
authors.initials: E
authors.lastname: Ghebremedhin
authors.forename: Domenico
authors.initials: D
authors.lastname: Del Turco
authors.forename: Janaky
authors.initials: J
authors.lastname: Coomaraswamy
authors.forename: Matthias
authors.initials: M
authors.lastname: Staufenbiel
authors.forename: Mathias
authors.initials: M
authors.lastname: Jucker
authors.forename: Thomas
authors.initials: T
authors.lastname: Deller
mesh_terms: D000544:Alzheimer Disease / Q000473:pathology*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D000906:Antibodies / Q000008:administration & dosage / Q000009:adverse effects*; D001921:Brain / Q000098:blood supply* / Q000187:drug effects / Q000473:pathology*; D002543:Cerebral Hemorrhage / Q000139:chemically induced* / Q000473:pathology*; D005260:Female; D007167:Immunotherapy / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008833:Microcirculation / Q000187:drug effects / Q000473:pathology; D016896:Treatment Outcome
chemical_list: D016564:Amyloid beta-Protein Precursor; D000906:Antibodies