A common antigenic motif recognized by naturally occurring human VH5\u201351/VL4\u20131 anti-tau antibodies with distinct functionalities

Adrian Apetri,Gabriel Pascual,Esther J M Stoop,Jeroenvan Ameijde,Hanna Inganäs,Trevin Holland,Berdien Siregar,Michael Mrosek,Hanneke Verveen,Stefan Steinbacher,Martin Koldijk ,Jarek Juraszek,Jay Wadia,Jeroen J M Hoozemans ,Marc Mercken,R W Janson ,Margot Van Winsen,Rosa Crespo,Wouter Koudstaal,Elissa Keogh,Kristof Van Kolen,Xueyong Zhu,David Zuijdgeest,Koen Dockx,Donata De Marco,Renske Taggenbrock,Kimberley Ummenthum,Ian A Wilson,Heng Zhang,M Borgers ,Els C Brinkman-Van Der Linden ,Wenli Yu,Jaap Goudsmit

doi:10.1186/s40478-018-0543-z

Abstract

Misfolding and aggregation of tau protein are closely associated with the onset and progression of Alzheimer’s Disease (AD). By interrogating IgG+ memory B cells from asymptomatic donors with tau peptides, we have identified two somatically mutated VH5–51/VL4–1 antibodies. One of these, CBTAU-27.1, binds to the aggregation motif in the R3 repeat domain and blocks the aggregation of tau into paired helical filaments (PHFs) by sequestering monomeric tau. The other, CBTAU-28.1, binds to the N-terminal insert region and inhibits the spreading of tau seeds and mediates the uptake of tau aggregates into microglia by binding PHFs. Crystal structures revealed that the combination of VH5–51 and VL4–1 recognizes a common Pro-Xn-Lys motif driven by germline-encoded hotspot interactions while the specificity and thereby functionality of the antibodies are defined by the CDR3 regions. Affinity improvement led to improvement in functionality, identifying their epitopes as new targets for therapy and prevention of AD.

Highlights

Intracellular neurofibrillary tangles (NFTs) consisting of aggregated tau protein are a hallmark of Alzheimer’s disease (AD) and other neurogenerative disorders, collectively referred to as tauopathies [31]
Identification of naturally occurring anti-tau antibodies in healthy donors In total, 2.6 × 106 memory B cells from nine healthy blood donors aged 18–65 years were interrogated against a pool of 10 overlapping peptides spanning the length of tau441 (Additional file 1: Table S1)
Two unique tau binding antibodies, CBTAU-27.1 and CBTAU-28.1, which are both derived from the VH5–51 and VL4–1 germline families, were identified

Summary

Introduction

Intracellular neurofibrillary tangles (NFTs) consisting of aggregated tau protein are a hallmark of Alzheimer’s disease (AD) and other neurogenerative disorders, collectively referred to as tauopathies [31]. Tau is a microtubuleassociated protein expressed predominantly in neuronal axons and promotes the assembly and stability of microtubules [9, 46]. It is expressed in the adult human brain as six isoforms with zero, one or two N-terminal acidic inserts (0N, 1N, or N) and either three or four microtubulebinding repeats (3R or 4R) [18]. We have recently described the isolation of a panel of antibodies with such functional activity by interrogating the peripheral IgG+ memory B cells of healthy human blood donors for reactivity to phosphorylated tau peptides [37]. To expand the arsenal of potential targets and include epitopes present in physiological tau, we used the BSelex technology in combination with a pool of unphosphorylated tau peptides as baits (Fig. 1a, and Additional file 1: Table S1 for peptide sequences)

Methods

Results

Conclusion