Monoclonal Antibodies against Aβ42 Fibrils Distinguish Multiple Aggregation State Polymorphisms in Vitro and in Alzheimer Disease Brain

Abstract

Background: Several amyloid proteins form conformationally distinct aggregates. Results: 23 antibodies raised against fibrillar A␤42 display 18 unique reactivity profiles. Conclusion:The immune response to fibrillar amyloid reflects the diversity in amyloid structures. Significance: The use of a single antibody in immunization therapies of Alzheimer disease may not be effective, as it is unable to target all structural variants of A␤.

Synaptic Amyloid-β Oligomers Precede p-Tau and Differentiate High Pathology Control Cases

“…ajp.amjpathol.org -The American Journal of Pathology anti-Ab antibodies are sensitive to conformation and differentially label aggregated Ab preparations. 46 As previously reported, synaptic terminals from control cases show little to no Ab immunolabeling ( Figure 1C) 26,33,42,47 ; representative plots from AD cases illustrate the rise in synaptic Ab with increasing neuropathologic disease stage and the degree to which synaptic terminal Ab increases between plaque stage 0 (no plaque deposition) and stage C (end-stage plaque deposition) (Figure 1, D and E). 48 Figure 2A shows group differences in aggregate flow cytometric data [F(3,30) Z 6.13, P Z 0.002] in both early-stage (Braak II to IV) and late-stage (Braak V to VI) AD cases.…”

“…56 Characterization of these antibodies has shown a number of distinct subtypes within the prefibrillar and fibrillar classes of Ab oligomers, illustrating the diversity of Ab oligomers in the AD brain. 46 Corresponding to human results, the ELISA for soluble oAb ( Figure 4F) in transgenic rat P-2 samples also shows age and genotype effects with significant elevations in each age group, beginning at 3 months [age: F(2,53) Z 44.10, P < 0.001; genotype: F(1,35) Z 54.13, P < 0.001; age  genotype interaction: F(2,35) Z 44.06, P < 0.001]. Importantly, subtle cognitive deficits are already detectable by 3 months of age in this model.…”

[P1–193]: Do Anti‐amyloid Beta Protein Antibody Cross Reactivities Confound Alzheimer Disease Research?

“…The only option to systematically detect specific peptides is to use multiple antibodies reacting with the different epitopes or use a capture antibody relevant to the experimental design, such as 4G8 as in [22] or 6E10 as in [3,22] and then analyse any fragments further with for example, mass spectroscopy. However, it must be born in mind that a single antibody will not capture all possible Aβ-or P3 type fragments in all aggregations states [39] and this must be explicitly accounted for in any experimental design. The different antigen retrieval methods [47], different profiles of Aβ-type fragments in soluble [22] and insoluble fractions and potential loss of epitopes due to aggregation state [39] add further difficulties in systematically characterising Aβ.…”

“…However, it must be born in mind that a single antibody will not capture all possible Aβ-or P3 type fragments in all aggregations states [39] and this must be explicitly accounted for in any experimental design. The different antigen retrieval methods [47], different profiles of Aβ-type fragments in soluble [22] and insoluble fractions and potential loss of epitopes due to aggregation state [39] add further difficulties in systematically characterising Aβ. A "panel" of antibodies to consistently and reliably characterise Aβ-type, P3-type and catabolic fragments in all aggregation states (monomer, dimer, oligomer and fibril) is not currently possible.…”

“…In human kidney 293 cell culture medium, approximately 69% of peptides released following γ-cleavage were found to be P3-type, around 20% are Aβ-type and 11% are Aβ'-type [37] however, different expression systems may give different ratios and these ratios may not reflect the levels of expression in the human brain. Shorter fragments in (35)(36)(37)(38)(39)(40)(41)(42) and Aβ (35)(36)(37)(38)(39)(40) are predicted from BACE2 catabolism of full length Aβ [8]. These shorter Aβ-type peptide sequences have been largely neglected in AD research and their expression levels in human tissues remains to be fully described.…”