Conformation-sensitive antibodies against alzheimer amyloid-beta by immunization with a thioredoxin-constrained B-cell epitope peptide.
Immunotherapy against the amyloid-beta (Abeta) peptide is a valuable potential treatment for Alzheimer disease (AD). An ideal antigen should be soluble and nontoxic, avoid the C-terminally located T-cell epitope of Abeta, and yet be capable of eliciting antibodies that recognize Abeta fibrils and neurotoxic Abeta oligomers but not the physiological monomeric species of Abeta. We have described here the construction and immunological characterization of a recombinant antigen with these features obtained by tandem multimerization of the immunodominant B-cell epitope peptide Abeta1-15 (Abeta15) within the active site loop of bacterial thioredoxin (Trx). Chimeric Trx(Abeta15)n polypeptides bearing one, four, or eight copies of Abeta15 were constructed and injected into mice in combination with alum, an adjuvant approved for human use. All three polypeptides were found to be immunogenic, yet eliciting antibodies with distinct recognition specificities. The anti-Trx(Abeta15)4 antibody, in particular, recognized Abeta42 fibrils and oligomers but not monomers and exhibited the same kind of conformational selectivity against transthyretin, an amyloidogenic protein unrelated in sequence to Abeta. We have also demonstrated that anti-Trx(Abeta15)4, which binds to human AD plaques, markedly reduces Abeta pathology in transgenic AD mice. The data indicate that a conformational epitope shared by oligomers and fibrils can be mimicked by a thioredoxin-constrained Abeta fragment repeat and identify Trx(Abeta15)4 as a promising new tool for AD immunotherapy.
Moretto
Nadia
N
Department of Biochemistry and Molecular Biology, Chiesi Farmaceutici, University of Parma, 43100 Parma, Italy.
Bolchi
Angelo
A
Rivetti
Claudio
C
Imbimbo
Bruno P
BP
Villetti
Gino
G
Pietrini
Vladimiro
V
Polonelli
Luciano
L
Del Signore
Steven
S
Smith
Karen M
KM
Ferrante
Robert J
RJ
Ottonello
Simone
S
D000544:Alzheimer Disease / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D000818:Animals; D000906:Antibodies / Q000276:immunology*; D001921:Brain / Q000378:metabolism / Q000473:pathology; D018985:Epitopes, B-Lymphocyte / Q000276:immunology*; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D008958:Models, Molecular; D010446:Peptide Fragments / Q000276:immunology*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D013879:Thioredoxins / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism
D016229:Amyloid beta-Peptides; D000906:Antibodies; D018985:Epitopes, B-Lymphocyte; D010446:Peptide Fragments; D011994:Recombinant Proteins; D013879:Thioredoxins