An “epitomic” analysis of the specificity of conformation-dependent, anti-Aß amyloid monoclonal antibodies

Abstract

Antibodies against Aß amyloid are indispensable research tools and potential therapeutics for Alzheimer’s disease. They display several unusual properties, such as specificity for aggregated forms of the peptide, the ability to distinguish polymorphic aggregate structures, and the ability to recognize generic aggregation-related epitopes formed by unrelated amyloid sequences. Understanding the mechanisms underlying these unusual properties and the structures of their corresponding epitopes is crucial for the understanding why antibodies display different therapeutic activities and for the development of more effective therapeutic agents. Here we employed a novel “epitomic” approach to map the fine structure of the epitopes of 28 monoclonal antibodies against amyloid-beta using immunoselection of random sequences from a phage display library, deep sequencing, and pattern analysis to define the critical sequence elements recognized by the antibodies. Although most of the antibodies map to major linear epitopes in the amino terminal 1 to 14 residues of Aß, the antibodies display differences in the target sequence residues that are critical for binding and in their individual preferences for nontarget residues, indicating that the antibodies bind to alternative conformations of the sequence by different mechanisms. Epitomic analysis also identifies discontinuous, nonoverlapping sequence Aß segments that may constitute the conformational epitopes that underlie the aggregation specificity of antibodies. Aggregation-specific antibodies recognize sequences that display a significantly higher predicted propensity for forming amyloid than antibodies that recognize the monomer, indicating that the ability of random sequences to aggregate into amyloid is a critical element of their binding mechanism.

Age-Related Oxidative Redox and Metabolic Changes Precede Intraneuronal Amyloid-β Accumulation and Plaque Deposition in a Transgenic Alzheimer’s Disease Mouse Model

“…To profile the development of Aβ aggregates across the lifespan of 3xTg AD-model mice, we performed immunostaining of brain sections using 6E10, an antibody that recognizes exposed residues 5–7 of the human Aβ peptide [ 51 ], and mOC78 antibodies that recognize a conformational epitope at positions 8–11 and 24–26 [ 52 ] of aggregates of oligomeric mouse and human Aβ peptide and other amyloids [ 7 ]. We examined the staining of large aggregates and plaques (>80 μm 2 ) in CA1 of the hippocampus, a region that is known to be affected early in AD [ 53 ].…”

Alzheimer's disease‐like neuropathology in three species of oceanic dolphin

“…Labelling of the perivascular neuropil of blood vessels was present in this study, and although this is a well‐documented in AD cases with CAA, it is typically associated with the shorter form of the peptide, Aβ40, which antibody mOC64 is not supposed to label (Reyes‐Ruiz et al, 2021). However, as the pathogenesis of Aβ accumulation in odontocetes is, as yet, unknown so antibody mOC64 may cross‐react with the shorter form of the Aβ in these species or the longer form may accumulate in the perivascular regions and further work using antibodies of known Aβ epitope, specificity is required to determine this possibility.…”

Polymorphic Alpha-Synuclein Oligomers: Characterization and Differential Detection with Novel Corresponding Antibodies

“…In this study, we employ biochemical and biophysical methods to investigate the biological and immunoreactive properties of three α-Syn oligomeric polymorphs utilizing established methods and three α-Syn Toxic Conformation Monoclonal Antibodies, SynTCs, developed by our lab. Initial epitope mapping data showed SynTC binding sites are discontinuous, nonoverlapping sequence patterns further suggesting conformational epitopes [ 68 ].…”