Faculty Bibliography

In cerebral amyloid angiopathy (CAA), amyloid fibrils deposit in walls of arteries, arterioles and less frequently in veins and capillaries of the central nervous system, often resulting in secondary degenerative vascular changes. Although the amyloid-beta peptide is by far the commonest amyloid subunit implicated in sporadic and rarely in hereditary forms of CAA, a number of other proteins may also be involved in rare familial diseases in which CAA is also a characteristic morphological feature. These latter proteins include the ABri and ADan subunits in familial British dementia and familial Danish dementia, respectively, which are also known under the umbrella term BRI2 gene-related dementias, variant cystatin C in hereditary cerebral haemorrhage with amyloidosis of Icelandic-type, variant transthyretins in meningo-vascular amyloidosis, disease-associated prion protein (PrP(Sc)) in hereditary prion disease with premature stop codon mutations and mutated gelsolin (AGel) in familial amyloidosis of Finnish type. In this review, the characteristic morphological features of the different CAAs is described and the implication of the biochemical, genetic and transgenic animal data for the pathogenesis of CAA is discussed

Background: PS1 mutations may increase Abeta production but their effect on tau expressionphosphorylation and/or aggregation has not been thoroughly assessed.We have previously shown that the M146L mutation does not lead to tau pathology in mice expressing one isoform of wild-type human tau (ON3R) but it does promote tau phosphorylation and aggregation inmice expressing all six isoforms of wild-type human tau on a mouse tau knock-out background (htau/PS1/mtau-/-). Methods: We have now analyzed further this accelerated pathologyand its time-dependence compared to htau/mtau-/- littermatesand are studying the possible pathways involved in this important interaction. The mice were killed at 2-35-6 and 8-9 months for brain analyses. Results: Pathological tau was observed on brain sections in the htau/PS1/mtau-/- mice but not in controls as early as at 2 months of ageit increased with ageand was routinely positive with Thioflavin S and occasionally with Gallyas silver stain. Total tau levels did not differ between the groups at any age but human tau CP27 bands shifted to a higher MW (hyperphosphorylation) in the new model compared to controls. Also, in those animals PHF1 IR soluble tau was increased by 142% and 219% compared to their htau/mtau-/- littermates at 5-6 months (p<0.02) and 8-9 months (p<0.002), respectively. Likewise, IHC analysis revealed an 83% increase in PHF1 IR tau in the pyriform cortex at 8-9 months, (p=0.02), and a comparable increase at 5-6 months and in AT8 IR (IHC and Western) that are being quantitated. Importantly, the htau/PS1/mtau-/- mice were more cognitively impaired than controls in the Radial Arm Maze (p<0.03). Analyses of other cortical and hippocampal regions with advanced tau pathology, with other tau antibodies as well as of insoluble tau is underway. Further-more, older animals, tau-related pathology and the potential involvement of various signaling pathways are being assessed. Conclusions: The M146L mutation promotes age-related tau phosphorylation and aggregation, and impairs cognition compared to controls, suggesting that PS1/tau interaction may be important in the etiology and/or pathogenesis of AD. This novel model can be very useful for studying the onset and progression of AD as well as for therapeutic studies

We have been developing Abeta derivative vaccines with the objective to improve the safety of Abeta targeting immunotherapy. Our Abeta homologs are designed to have less direct toxicity and to produce a modified immune response compared to Abeta. In extensive mouse studies, all our vaccines have improved cognition in transgenic mice while eliciting different immune responses and reducing brain amyloid burden to a variable degree. While we are continuing to characterize these vaccines in mice, in preparation for studies in old primates and for human trials we assessed their effect in young lemur primates (n=25) that with age develop Abeta plaques and tau aggregates as seen in Alzheimer's disease. In the primates, all the peptides administered with alum adjuvant elicited a moderate to robust anti-Abeta IgM response. Abeta1-42, K6Abeta1-30 and K6Abeta1-30[E(18)E(19)] resulted in a high anti-Abeta IgG response, whereas Abeta1-30[E(18)E(19)] produced a weaker more variable IgG titer. Notably, 22 weeks after the 3rd immunization, IgM and IgG levels in derivative-vaccinated primates were similar to preimmune values whereas Abeta1-42 treated primates maintained a moderate IgG titer. The increase in antibodies that recognized Abeta1-40 often correlated with increase in Abeta1-40 in plasma, which suggests that the antibodies were binding to Abeta in vivo. Interestingly, significant transient weight gain was observed (K6Abeta1-30-, Abeta1-30[E(18)E(19)]- and Abeta1-42-treated) or a trend in the same direction (K6Abeta1-30[E(18)E(19)]-treated, adjuvant controls) following the injections. Based on these findings, we have chosen K6Abeta1-30 for immunizations in old primates as the antibody response to this vaccine was less variable compared to other Abeta derivatives. Our present findings indicate that most of our Abeta derivatives elicit a substantial antibody response in primates, and importantly this effect is reversible which enhances the safety profile of our approach

Immunotherapy holds great promise for Alzheimer's disease (AD) and other conformational disorders but certain adverse reactions need to be overcome. Prior to the side effects in the first Elan/Wyeth AD vaccine trial, we proposed using amyloid-beta (Abeta) derivatives as a safer approach. The route of administration may also affect vaccine safety. To assess the feasibility of oral immunization that promotes mucosal immunity, Tg2576 AD model mice were treated prophylactically three times over 6 weeks starting at 3-5 months of age with a Salmonella vaccine expressing K6Abeta<formula> _{1-30}</formula>. At 22-24 months of age, cortical Abeta plaque burden and total Abeta<formula>_{40}</formula>/<formula>_{42}</formula> levels were reduced by 48-75% in the immunized mice compared to controls, which received unmodified Salmonella. Plaque clearance was not associated with increased microglial activation which may be explained by the long treatment period. Furthermore, cerebral microhemorrhages were not increased in the treated mice in contrast to several passive Abeta antibody studies. These results further support our findings with this immunogen delivered subcutaneously and demonstrate its efficacy when given orally which may provide added benefits for human use

The present invention relates to immunogenic but non-depositing-forming polypeptides or peptides homologous to amyloid beta, prion, amylin or alpha-synuclein which can be used alone or conjugated to an immunostimulatory molecule in an immunizing composition for inducing an immune response to amyloid beta peptides and amyloid deposits, to prion protein and prion deposits, to amylin and amylin deposits, to alpha-synuclein and deposits containing alpha-synuclein, or to polyglutamine repeats and deposits of proteins containing polyglutamine repeats. Described are also antibodies directed against such peptides, their generation, and their use in methods of passive immunization to such peptides and deposits

INTRODUCTION: Two different disease-specific mutations in the BRI2 gene, situated on chromosome 13, have been identified as giving rise to familial British dementia (FBD) and familial Danish dementia (FDD). Each mutation results in extension of the open reading frame generating the disease-specific precursor proteins which are cleaved by furin-like proteolysis releasing the amyloidogenic C-terminal peptides ABri and ADan in FBD and FDD, respectively. MATERIAL AND METHODS: To understand the mechanism of the formation of amyloid lesions in FBD, we studied the origin of the precursor proteins and furin in the human brain. We used control brains, cases of sporadic Alzheimer's disease (AD), variant AD with cotton wool plaques and FBD to study BRI2 mRNA expression using in situ hybridization. Furin and BRI2 protein expression was investigated using Western blotting and immunohistochemistry. RESULTS: BRI2 mRNA and BRI2 protein are widely expressed primarily by neurones and glia and are deposited in the amyloid lesions in FBD. They were, however, not expressed by cerebrovascular components. Furin expression showed a similar pattern except that it was also present in cerebrovascular smooth muscle cells. CONCLUSIONS: These findings suggest that neurones and glia and are a major source of BRI2 protein and that in FBD, the mutated precursor protein may undergo furin cleavage within neurones to produce the amyloid peptide ABri. The failure to demonstrate BRI2 in blood vessels under the conditions tested suggests that vascular amyloid peptide production does not contribute significantly to cerebral amyloid angiopathy (CAA) in FBD and FDD, lending indirect support to the drainage hypothesis of CAA

The present invention relates to synthetic immunogenic but non-amyloidogenic peptides homologous to amyloid beta which can be used alone or conjugated to an immunostimulatory molecule in an immunizing composition for inducing an immune response to amyloid beta peptides and amyloid deposits