Nathalie Chuard

Liposomal vaccines with conformation-specific amyloid peptide antigens define immune response and efficacy in APP transgenic mice

We investigated the therapeutic effects of two different versions of Aβ1–15 (16) liposome-based vaccines. Inoculation of APP-V717IxPS-1 (APPxPS-1) double-transgenic mice with tetra-palmitoylated amyloid 1–15 peptide (palmAβ1–15), or with amyloid 1–16 peptide (PEG-Aβ1–16) linked to a polyethyleneglycol spacer at each end, and embedded within a liposome membrane, elicited fast immune responses with identical binding epitopes. PalmAβ1–15 liposomal vaccine elicited an immune response that restored the memory defect of the mice, whereas that of PEG-Aβ1–16 had no such effect. Immunoglobulins that were generated were predominantly of the IgG class with palmAβ1–15, whereas those elicited by PEG-Aβ1–16 were primarily of the IgM class. The IgG subclasses of the antibodies generated by both vaccines were mostly IgG2b indicating noninflammatory Th2 isotype. CD and NMR revealed predominantly β-sheet conformation of palmAβ1–15 and random coil of PEG-Aβ1–16. We conclude that the association with liposomes induced a variation of the immunogenic structures and thereby different immunogenicities. This finding supports the hypothesis that Alzheimers disease is a “conformational” disease, implying that antibodies against amyloid sequences in the β-sheet conformation are preferred as potential therapeutic agents.

Efficacy and Safety of A Liposome-Based Vaccine against Protein Tau, Assessed in Tau.P301L Mice That Model Tauopathy

Progressive aggregation of protein Tau into oligomers and fibrils correlates with cognitive decline and synaptic dysfunction, leading to neurodegeneration in vulnerable brain regions in Alzheimers disease. The unmet need of effective therapy for Alzheimers disease, combined with problematic pharmacological approaches, led the field to explore immunotherapy, first against amyloid peptides and recently against protein Tau. Here we adapted the liposome-based amyloid vaccine that proved safe and efficacious, and incorporated a synthetic phosphorylated peptide to mimic the important phospho-epitope of protein Tau at residues pS396/pS404. We demonstrate that the liposome-based vaccine elicited, rapidly and robustly, specific antisera in wild-type mice and in Tau.P301L mice. Long-term vaccination proved to be safe, because it improved the clinical condition and reduced indices of tauopathy in the brain of the Tau.P301L mice, while no signs of neuro-inflammation or other adverse neurological effects were observed. The data corroborate the hypothesis that liposomes carrying phosphorylated peptides of protein Tau have considerable potential as safe and effective treatment against tauopathies, including Alzheimers disease.

TLR4- and TRIF-dependent stimulation of B lymphocytes by peptide liposomes enables T cell-independent isotype switch in mice.

Immunoglobulin class switching from IgM to IgG in response to peptides is generally T cell-dependent and vaccination in T cell-deficient individuals is inefficient. We show that a vaccine consisting of a dense array of peptides on liposomes induced peptide-specific IgG responses totally independent of T-cell help. Independency was confirmed in mice lacking T cells and in mice deficient for MHC class II, CD40L, and CD28. The IgG titers were high, long-lived, and comparable with titers obtained in wild-type animals, and the antibody response was associated with germinal center formation, expression of activation-induced cytidine deaminase, and affinity maturation. The T cell-independent (TI) IgG response was strictly dependent on ligation of TLR4 receptors on B cells, and concomitant TLR4 and cognate B-cell receptor stimulation was required on a single-cell level. Surprisingly, the IgG class switch was mediated by TIR-domain-containing adapter inducing interferon-β (TRIF), but not by MyD88. This study demonstrates that peptides can induce TI isotype switching when antigen and TLR ligand are assembled and appropriately presented directly to B lymphocytes. A TI vaccine could enable efficient prophylactic and therapeutic vaccination of patients with T-cell deficiencies and find application in diseases where induction of T-cell responses contraindicates vaccination, for example, in Alzheimer disease.

A liposomal anti-phospho-tau vaccine demonstrates higher immunogenicity and specificity than a classical peptide vaccine approach

However, the relationship between these two proteins and neuronal loss lacks amechanistic explanation. Furthermore, evidence from animal models suggests that amyloid beta toxicity is mediated by tau [1-6]. We hypothesize that tau oligomers formation plays curial role in driving AD pathogenesis. Thus, tau oligomers represent an ideal therapeutic target for the treatment of AD. In order to study the removal of toxic tau assemblies in an animal model of AD (Tg2576), we generated a tau oligomer specific antibody (TOMA). This antibody does not recognize the functional monomeric tau or oligomers from other amyloidogenic proteins. Methods: Here we used the Tg2576 mouse model which overexpress the human APP with the Swedish double mutations (K670N, M671L) under the control of a hamster prion protein promoter .14-month old Tg2576 mice, received a single iv injection of 30 mg of the TOMA antibody. Control group received 30 mg of non-specific IgG. Cognitive function was assessed by novel object recognition test, 15 days after injection. In addition, western blot, ELISA and Immunostaining were performed to evaluate the response to treatment. Results: Our results indicate that single iv-injection of the TOMA antibody, reduce endogenous tau oligomers and improve cognition in the Tg2576 mouse. Interestingly, removal of tau oligomers by immunotherapy decreases beta-amyloid-56* and increases deposition of plaques in immunized mice. Conclusions: Our results support the findings that tau oligomers mediate beta-amyloid toxicity in vivo. Moreover, removal of tau oligomers by immunotherapy may induce beta-amyloid aggregates to assembly into inert and perhaps protective plaques. Thus, targeting tau oligomers by immunotherapymay represent a novel strategy for the treatment of AD and other neurodegenerative tauopathies.

Novel phospho-tau-specific liposome-based vaccines to treat tau pathology

Clara Theunis, Natalia Crespo-Biel, Maria Pihlgren, Peter Borghgraef, Herman Devijver, Valerie Gafner, David Hickman, Nathalie Chuard, Maria Pilar Lopez Deber, Pedro Reis, Anna Lucia Buccarello, Oskar Adolfsson, Sigrun Roeber, Hans Kretzschmar, Andrea Pfeifer, Andreas Muhs, Fred Van Leuven, LEGTEGG Katholieke Universiteit Leuven, Leuven, Belgium; 2 ACImmune, Lausanne, Switzerland; LEGTEGGKULeuven, Leuven, Belgium; LEGTEGG-KULeuven, Leuven, Belgium; AC Immune SA, Lausanne, Switzerland; Center for Neuropathology, M€unchen, Germany; 7 AC Immune, Lausanne, Switzerland; 8 Experimental Genetics Group LEGTEGG KULeuven, Leuven, Belgium.

Novel phospho-Tau specific monoclonal antibodies for the treatment of Tau-mediated pathology

Background: Research over the last decade has highlighted the role that metals may play in the pathogenesis of Alzheimer’s disease (AD). To date, the primary end point for these studies has been s-amyloid. Recent literature supports the notion that metals may also interact with tau and be important for the formation of neurofibrillary tangles (NFTs). In this study we surveyed metal levels in the rTg(tauP301L)4510 mouse model and utilised clioquinol (CQ) to assess the effect of metal modulation on tangle pathology. Methods: Metal levels were assessed by ICPMS in cohorts of mice at either w2 months (n 1⁄4 6 WT; n 1⁄4 6 Tg) or w5 months (n 1⁄4 12 WT; n 1⁄4 11 Tg) of age. The effect of oral clioquinol (6 months of treatment, 30mg/kg) was assessed in a separate cohort of Tg (n 1⁄4 25) and WT mice (n 1⁄4 30). Drug treatment began at w6 months of age and prior to culling animals were assessed in the open field, rotarod, y-maze and water maze. Young rTg4510 mice, prior to the formation of any pathology, had significantly altered brain metal content, including elevations in zinc (25%, p 1⁄4 0.01) and copper (31%, p 1⁄4 0.02) and a trend to elevated iron (20%, p 1⁄4 0.08). In contrast, aged rTg4510 mice had significantly decreased levels of zinc (18%, p 1⁄4 0.01) and iron levels were also decreased (20%, p 1⁄4 0.06). Behavioural analysis of older mice did not reveal any effect of CQ on performance in the water maze, Y-maze or open field. In the rotarod, however, the Tg animals spent a significantly shorter amount of time on the rotarod (3.5 sec, Tg; 35 sec, WT; p < 0.0001), and clioquinol treatment of the Tg animals significantly improved their performance (10.2 sec, Tg+clioquinol; p 1⁄4 0.01 compared to Tg). Further metal analyses and histological studies are currently being finalised and will be discussed. Conclusions: We have demonstrated that there is a dysregulation in metal ion homeostasis in the rTg4510 model of tauopathy, and that there are also age-dependent alterations in metal levels that occur coincident with the evolution of neurofibrillary pathology. These data support a potential interaction between tau/NFTs and various metal ions and provide further insight into novel therapeutic approaches for the treatment of tauopathies.