Vaccination with soluble Aβ oligomers generates toxicity‐neutralizing antibodies

Abstract

In recent studies of transgenic models of Alzheimer's disease (AD), it has been reported that antibodies to aged beta amyloid peptide 1±42 (Ab 1242 ) solutions (mixtures of Ab monomers, oligomers and amyloid ®brils) cause conspicuous reduction of amyloid plaques and neurological improvement. In some cases, however, neurological improvement has been independent of obvious plaque reduction, and it has been suggested that immunization might neutralize soluble, non®brillar forms of Ab. It is now known that Ab toxicity resides not only in ®brils, but also in soluble proto®brils and oligomers. The current study has investigated the immune response to low doses of Ab 1242 oligomers and the characteristics of the antibodies they induce. Rabbits that were injected with Ab 1242 solutions containing only monomers and oligomers produced antibodies that preferentially bound to assembled forms of Ab in immunoblots and in physiological solutions. The antibodies have proven useful for assays that can detect inhibitors of oligomer formation, for immuno¯uorescence localization of cell-attached oligomers to receptor-like puncta, and for immunoblots that show the presence of SDS-stable oligomers in Alzheimer's brain tissue. The antibodies, moreover, were found to neutralize the toxicity of soluble oligomers in cell culture. Results support the hypothesis that immunizations of transgenic mice derive therapeutic bene®t from the immunoneutralization of soluble Ab-derived toxins. Analogous immuno-neutralization of oligomers in humans may be a key in AD vaccines.

Blockade of EphA4 signaling ameliorates hippocampal synaptic dysfunctions in mouse models of Alzheimer’s disease

“…Oligomeric Aβ was prepared as described previously (45). Ephrin-A1-Fc was preclustered with goat antihuman Fc antibody (1:4.5) (16).…”

Conformation-sensitive Antibodies against Alzheimer Amyloid-β by Immunization with a Thioredoxin-constrained B-cell Epitope Peptide

“…A␤42 dissolved in 2 M dimethyl sulfoxide (1 mM final concentration) was utilized for the preparation of aggregated A␤42 species (19,21,45). A 10-fold dilution of the above stock solution into cold Ham's F-12 K medium (phenol red-free; BIOSOURCE) followed by incubation at 4°C for 24 h was used to produce soluble oligomers; the same stock solution diluted into 10 mM HCl at a final concentration of 100 M and incubated for 24 h at 37°C was used to generate A␤ fibrils.…”

“…Also important in this regard is the availability of A␤ peptide formulations capable of eliciting antibodies that recognize specific assembly states of A␤42 (19, 34 -36). For example, antibodies binding to oligomeric and fibrillar (but not to monomeric) A␤, have been produced by using purified A␤42 oligomers (19) or nitrated A␤40 (35) as antigens, whereas antibodies selectively recognizing soluble A␤ oligomers have been obtained by immunization with A␤40 immobilized onto gold nanoparticles (36). Interestingly, the latter antibodies bind not only to A␤ oligomers but also to the oligomeric forms of various A␤-unrelated amyloidogenic polypeptides, suggesting that a common (as yet unidentified) conformation-dependent structure is shared by soluble oligomers regardless of their sequence (36).…”

Preparation and characterization of toxic Aβ aggregates for structural and functional studies in Alzheimer's disease research

“…This hypothesis is supported by (i) the lack of a clear correlation between fibrillar amyloid burden in AD patients and cognitive impairment 29,30 , whereas such a correlation has been reported for the soluble pool of Aβ (monomers and oligomers including protofibrils) and AD severity 31,32 ; (ii) the fact that autosomal dominant mutations in APP or its cleaving enzymes (presenilins), which favor increased production of Aβ42 and/or accumulation of protofibrils, are associated with the development of fAD [33][34][35][36] ; (iii) the indication that transgenic animals overexpressing fAD mutations in APP exhibit learning deficits and lower performance in memory tasks, compared with control animals, long before the appearance of amyloid plaques 37,38 ; (iv) the fact that intracerebral administration of soluble Aβ oligomers in live animals impairs cognitive performance and inhibits long-term potentiation (LTP), a cellular model of memory formation 19 , and induces widespread plaque pathology 39 ; and (v) the observation that treating cultured neurons with Aβ protofibrils results in impairment of ion channelss 40,41 , inhibition of LTP 42 , loss of synapses and cell death 14 . Finally, anti-Aβ antibodies specifically targeting oligomers, including protofibrils, block neurotoxicity in cultured neurons 43 and reverse behavioral deficits in mice 44 . Therefore, there is a vast academic, medical and commercial interest in identifying therapeutic agents that target specifically soluble Aβ (monomers and oligomers, including protofibrils) and their impact on AD pathogenesis.…”