Nasal inoculation of an adenovirus vector encoding 11 tandem repeats of Abeta1-6 upregulates IL-10 expression and reduces amyloid load in a Mo/Hu APPswe PS1dE9 mouse model of Alzheimer's disease

BACKGROUND: One of the pathological hallmarks of Alzheimer's disease (AD) is deposits of amyloid beta-peptide (Abeta) in neuritic plaques and cerebral vessels. Immunization of AD mouse models with Abeta reduces Abeta deposits and improves memory and learning deficits. Because recent clinical trials of immunization with Abeta were halted due to brain inflammation that was presumably induced by a T-cell-mediated autoimmune response, vaccination modalities that elicit predominantly humoral immune responses are currently being developed. METHODS: We have nasally immunized a young AD mouse model with an adenovirus vector encoding 11 tandem repeats of Abeta1-6 fused to the receptor-binding domain (Ia) of Pseudomonas exotoxin A (PEDI), AdPEDI-(Abeta1-6)(11), in order to evaluate the efficacy of the vector in preventing Abeta deposits in the brain. We also have investigated immune responses of mice to AdPEDI-(Abeta1-6)(11). RESULTS: Nasal immunization of an AD mouse model with AdPEDI-(Abeta1-6)(11) elicited a predominant IgG1 response and reduced Abeta load in the brain. The plasma IL-10 level in the AD mouse model was upregulated after immunization and, upon the stimulation with PEDI-(Abeta1-6)(11), marked IL-10 responses were found in splenic CD4(+) T cells from C57BL/6 mice that had been immunized with AdPEDI-(Abeta1-6)(11). CONCLUSIONS: These results suggest that the induction of Th2-biased responses with AdPEDI-(Abeta1-6)(11) in mice is mediated in part through the upregulation of IL-10, which inhibits activation of dendritic cells that dictate the induction of Th1 cells.     

Transgenic potato expressing Abeta reduce Abeta burden in Alzheimer's disease mouse model

Beta amyloid (Abeta) is believed one of the major pathogens of Alzheimer's disease (AD), and the reduction of Abeta is considered a primary therapeutic target. Immunization with Abeta can reduce Abeta burden and pathological features in transgenic AD model mice. Transgenic potato plants were made using genes encoding 5 tandem repeats of Abeta1-42 peptides with an ER retention signal. Amyloid precursor protein transgenic mice (Tg2576) fed with transgenic potato tubers with adjuvant showed a primary immune response and a partial reduction of Abeta burden in the brain. Thus, Abeta tandem repeats can be expressed in transgenic potato plants to form immunologically functional Abeta, and these potatoes has a potential to be used for the prevention and treatment of AD.     

The Tottori (D7N) and English (H6R) familial Alzheimer disease mutations accelerate Abeta fibril formation without increasing protofibril formation

A subset of Alzheimer disease cases is caused by autosomal dominant mutations in genes encoding the amyloid beta-protein precursor or presenilins. Whereas some amyloid beta-protein precursor mutations alter its metabolism through effects on Abeta production, the pathogenic effects of those that alter amino acid residues within the Abeta sequence are not fully understood. Here we examined the biophysical effects of two recently described intra-Abeta mutations linked to early-onset familial Alzheimer disease, the D7N Tottori-Japanese and H6R English mutations. Although these mutations do not affect Abeta production, synthetic Abeta(1-42) peptides carrying D7N or H6R substitutions show enhanced fibril formation. In vitro analysis using Abeta(1-40)-based mutant peptides reveal that D7N or H6R mutations do not accelerate the nucleation phase but selectively promote the elongation phase of amyloid fibril formation. Notably, the levels of protofibrils generated from D7N or H6R Abeta were markedly inhibited despite enhanced fibril formation. These N-terminal Abeta mutations may accelerate amyloid fibril formation by a unique mechanism causing structural changes of Abeta peptides, specifically promoting the elongation process of amyloid fibrils without increasing metastable intermediates.     

Degradation of the amyloid beta-protein by the novel mitochondrial peptidasome, PreP

Recently we have identified the novel mitochondrial peptidase responsible for degrading presequences and other short unstructured peptides in mitochondria, the presequence peptidase, which we named PreP peptidasome. In the present study we have identified and characterized the human PreP homologue, hPreP, in brain mitochondria, and we show its capacity to degrade the amyloid beta-protein (Abeta). PreP belongs to the pitrilysin oligopeptidase family M16C containing an inverted zinc-binding motif. We show that hPreP is localized to the mitochondrial matrix. In situ immuno-inactivation studies in human brain mitochondria using anti-hPreP antibodies showed complete inhibition of proteolytic activity against Abeta. We have cloned, overexpressed, and purified recombinant hPreP and its mutant with catalytic base Glu(78) in the inverted zinc-binding motif replaced by Gln. In vitro studies using recombinant hPreP and liquid chromatography nanospray tandem mass spectrometry revealed novel cleavage specificities against Abeta-(1-42), Abeta-(1-40), and Abeta Arctic, a protein that causes increased protofibril formation an early onset familial variant of Alzheimer disease. In contrast to insulin degrading enzyme, which is a functional analogue of hPreP, hPreP does not degrade insulin but does degrade insulin B-chain. Molecular modeling of hPreP based on the crystal structure at 2.1 A resolution of AtPreP allowed us to identify Cys(90) and Cys(527) that form disulfide bridges under oxidized conditions and might be involved in redox regulation of the enzyme. Degradation of the mitochondrial Abeta by hPreP may potentially be of importance in the pathology of Alzheimer disease.     

Immunohistochemical investigation of amyloid beta-protein (Abeta) in the brain of aged cats

To clarify the immunohistochemical features of amyloid deposits and cerebral amyloid angiopathy (CAA), the distribution of the amyloid beta-protein subtypes Abeta40, Abeta42, Abeta43 and Abeta precursor protein (APP) were examined in the brains of fourteen aged cats (7.5-21 year-old). Two types of plaques were detected. The first type was characterized by Ass positive antigenic material and detected in the cortical layers of the frontal and parietal lobes of all examined cats. The second type was characterized by diffuse positive immune staining representing diffuse plaques, which were detected only in the very aged cats (17-21 years old) and distributed throughout the cortical layers of the parietal lobes. Vascular amyloid and the amyloid deposits were strongly positive-stained with the antibody Abeta42. APP was exhibited in neurons and axons while the staining was stronger in the very aged cats (17-21 years old). Our findings suggest that the feline forms a spontaneous model for understanding the early changes of normal brain aging and the early stage of amyloid beta-protein deposition.     

Amelioration of amyloid load by anti-Abeta single-chain antibody in Alzheimer mouse model

Parenteral immunization of transgenic mouse models of Alzheimer disease (AD) with synthetic amyloid beta-peptide (Abeta) prevented or reduced Abeta deposits and attenuated their memory and learning deficits. A clinical trial of immunization with synthetic Abeta, however, was halted due to brain inflammation, presumably induced by a toxic Abeta, T-cell- and/or Fc-mediated immune response. Another issue relating to such immunizations is that some AD patients may not be able to raise an adequate immune response to Abeta vaccination due to immunological tolerance or age-associated decline. Because peripheral administration of antibodies against Abeta also induced clearance of amyloid plaques in the model mice, injection of humanized Abeta antibodies has been proposed as a possible therapy for AD. By screening a human single-chain antibody (scFv) library for Abeta immunoreactivity, we have isolated a scFv that specifically reacts with oligomeric Abeta as well as amyloid plaques in the brain. The scFv inhibited Abeta amyloid fibril formation and Abeta-mediated cytotoxicity in vitro. We have tested the efficacy of the human scFv in a mouse model of AD (Tg2576 mice). Relative to control mice, injections of the scFv into the brain of Tg2576 mice reduced Abeta deposits. Because scFvs lack the Fc portion of the immunoglobulin molecule, human scFvs against Abeta may be useful to treat AD patients without eliciting brain inflammation.     

Glutamine synthetase, hemoglobin alpha-chain, and macrophage migration inhibitory factor binding to amyloid beta-protein: their identification in rat brain by a novel affinity chromatography and in Alzheimer's disease brain by immunoprecipitation

Proteins binding to amyloid beta-protein (Abeta) may modulate the accumulation of Abeta in Alzheimer's disease (AD) brain. We developed a monomeric Abeta column for isolation of the proteins binding to Abeta from rat brain. By amino acid sequence analysis and immunoreactivity with specific antibodies, we identified three new Abeta-binding proteins, glutamine synthetase, hemoglobin alpha-chain, and macrophage migration inhibitory factor as well as serum albumin, beta-tubulin, and glyceraldehyde-3-phosphate dehydrogenase already identified as proteins bound to amyloid beta-protein precursor. In addition, the retained fraction contained both apolipoprotein E and alpha(1)-antichymotrypsin already known as Abeta binding proteins. Furthermore, we detected the complexes of these new binding proteins with Abeta in a soluble fraction of the cerebral cortex of AD brain by immunoprecipitation. Our results suggest that these binding proteins also associate with Abeta, leading to the clearance or the accumulation of Abeta and the neuronal cell damage in human brain.     

Antibodies to beta-amyloid decrease the blood-to-brain transfer of beta-amyloid peptide

Amyloid-beta peptides (Abeta) play an important role in the pathophysiology of dementia of the Alzheimer's type and in amyloid angiopathy. Abeta outside the CNS could contribute to plaque formation in the brain where its entry would involve interactions with the blood-brain barrier (BBB). Effective antibodies to Abeta have been developed in an effort to vaccinate against Alzheimer's disease. These antibodies could interact with Abeta in the peripheral blood, block the passage of Abeta across the BBB, or prevent Abeta deposition within the CNS. To determine whether the blocking antibodies act at the BBB level, we examined the influx of radiolabeled Abeta (125I-Abeta(1-40)) into the brain after ex-vivo incubation with the antibodies. Antibody mAb3D6 (élan Company) reduced the blood-to-brain influx of Abeta after iv bolus injection. It also significantly decreased the accumulation of Abeta in brain parenchyma. To confirm the in-vivo study and examine the specificity of mAb3D6, in-situ brain perfusion in serum-free buffer was performed after incubation of 125I-Abeta(1-40) with another antibody mAbmc1 (DAKO Company). The presence of mAbmc1 also caused significant reduction of the influx of Abeta into the brain after perfusion. Therefore, effective antibodies to Abeta can reduce the influx of Abeta(1-40) into the brain.     

IgG‐single chain Fv fusion protein therapeutic for alzheimer's disease: Expression in CHO cells and pharmacokinetics and brain delivery in the rhesus monkey

Monoclonal antibodies (MAb) directed against the Abeta amyloid peptide of Alzheimer's disease (AD) are potential new therapies for AD, since these antibodies disaggregate brain amyloid plaque. However, the MAb is not transported across the blood–brain barrier (BBB). To enable BBB transport, a single chain Fv (ScFv) antibody against the Abeta peptide of AD was re‐engineered as a fusion protein with the MAb against the human insulin receptor (HIR). The HIRMAb acts as a molecular Trojan horse to ferry the ScFv therapeutic antibody across the BBB. Chinese hamster ovary (CHO) cells were stably transfected with a tandem vector encoding the heavy and light chains of the HIRMAb–ScFv fusion protein. A high secreting line was isolated following methotrexate amplification and dilutional cloning. The HIRMAb–ScFv fusion protein in conditioned serum‐free medium was purified by protein A affinity chromatography. The fusion protein was stable as a liquid formulation, and retained high‐affinity binding of both the HIR and the Abeta amyloid peptide. The HIRMAb–ScFv fusion protein was radiolabeled with the ¹²⁵I‐Bolton–Hunter reagent, followed by measurement of the pharmacokinetics of plasma clearance and brain uptake in the adult Rhesus monkey. The HIRMAb–ScFv fusion protein was rapidly cleared from plasma and was transported across the primate BBB in vivo. In conclusion, the HIRMAb–ScFv fusion protein is a new class of antibody‐based therapeutic for AD that has been specifically engineered to cross the human BBB. Biotechnol. Bioeng. 2010; 105: 627–635. © 2009 Wiley Periodicals, Inc.     

The neuronal adaptor protein X11beta reduces amyloid beta-protein levels and amyloid plaque formation in the brains of transgenic mice

Accumulation of cerebral amyloid beta-protein (Abeta) is believed to be part of the pathogenic process in Alzheimer's disease. Abeta is derived by proteolytic cleavage from a precursor protein, the amyloid precursor protein (APP). APP is a type-1 membrane-spanning protein, and its carboxyl-terminal intracellular domain binds to X11beta, a neuronal adaptor protein. X11beta has been shown to inhibit the production of Abeta in transfected non-neuronal cells in culture. However, whether this is also the case in vivo in the brain and whether X11beta can also inhibit the deposition of Abeta as amyloid plaques is not known. Here we show that transgenic overexpression of X11beta in neurons leads to a decrease in cerebral Abeta levels in transgenic APPswe Tg2576 mice that are a model of the amyloid pathology of Alzheimer's disease. Moreover, overexpression of X11beta retards amyloid plaque formation in these APPswe mice. Our findings suggest that modulation of X11beta function may represent a novel therapeutic approach for preventing the amyloid pathology of Alzheimer's disease.     

Humoral immune response to fibrillar beta-amyloid peptide

The beta-amyloid peptide (Abeta) is a normal product of the proteolytic processing of its precursor (beta-APP). Normally, it elicits a very low humoral immune response; however, the aggregation of monomeric Abeta to form fibrillar Abeta amyloid creates a neo-epitope, to which antibodies are generated. Rabbits were injected with fibrillar human Abeta(1-42), and the resultant antibodies were purified and their binding properties characterized. The antibodies bound to an epitope in the first eight residues of Abeta and required a free amino terminus. Additional residues did not affect the affinity of the epitope as long as the peptide was unaggregated; the antibody bound Abeta residues 1-8, 1-11, 1-16, 1-28, 1-40, and 1-42 with similar affinities. In contrast, the antibodies bound approximately 1000-fold more tightly to fibrillar Abeta(1-42). Their enhanced affinity did not result from their bivalent nature: monovalent Fab fragments exhibited a similar affinity for the fibrils. Nor did it result from the particulate nature of the epitope: monomeric Abeta(1-16) immobilized on agarose and soluble Abeta(1-16) exhibited similar affinities for the antifibrillar antibodies. In addition, antibodies raised to four nonfibrillar peptides corresponding to internal Abeta sequences did not exhibit enhanced affinity for fibrillar Abeta(1-42). Antibodies directed to the C-terminus of Abeta bound poorly to fibrillar Abeta(1-42), which is consistent with models where the carboxyl terminus is buried in the interior of the fibril and the amino terminus is on the surface. When used as an immunohistochemical probe, the antifibrillar Abeta(1-42) IgG exhibited enhanced affinity for amyloid deposits in the cerebrovasculature. We hypothesize either that the antibodies recognize a specific conformation of the eight amino-terminal residues of Abeta, which is at least 1000-fold more favored in the fibril than in monomeric peptides, or that affinity maturation of the antibodies produces an additional binding site for the amino-terminal residues of an adjacent Abeta monomer. In vivo this specificity would direct the antibody primarily to fibrillar vascular amyloid deposits even in the presence of a large excess of monomeric Abeta or its precursor. This observation may explain the vascular meningeal inflammation that developed in Alzheimer's disease patients immunized with fibrillar Abeta. Passive immunization with an antibody directed to an epitope hidden in fibrillar Abeta and in the transmembrane region of APP might be a better choice in the search for an intervention to remove Abeta monomers without provoking an inflammatory response.     

The underestimated potential of the immune system in prevention of Alzheimer's disease pathology

Genetic and environmental factors leading to Alzheimer's disease (AD) converge in a pathogenic pathway that leads to the accumulation of mis-folded amyloid peptide (Abeta) in the brain. Removal of Abeta from the brain has thus been the focus of academic and industrial research in the last decade. The concept of immunization therapy could be proven in animal models mimicking amyloid pathology but a multicenter clinical trial in which AD patients were vaccinated with aggregated Abeta has resulted in somewhat unanticipated and partially conflicting results. The occurrence of meningoencephalitis in 6% of vaccinated individuals forced the discontinuation of the clinical study, preventing the generation of sufficient data for an unequivocal statement about the effectiveness of such a therapy approach. This study, however, clearly showed that vaccination induced the production of antibodies against Abeta in some immunized patients. Moreover, circulating anti-Abeta antibodies are found in healthy humans suggesting a protective role of such physiological antibodies. Nonetheless, the physiological role of the immune system in preventing AD is not fully understood. This article summarizes crucial animal and clinical data underscoring the potential of the immune system for AD treatment.     

Formation of toxic fibrils of Alzheimer's amyloid beta-protein-(1-40) by monosialoganglioside GM1, a neuronal membrane component

A pathological hallmark of Alzheimer's disease (AD) is the deposition of amyloid beta-protein (Abeta) in fibrillar form on neuronal cells. However, the role of Abeta fibrils in neuronal dysfunction is highly controversial. This study demonstrates that monosialoganglioside GM1 (GM1) released from damaged neurons catalyzes the formation of Abeta fibrils, the toxicity and the cell affinity of which are much stronger than those of Abeta fibrils formed in phosphate-buffered saline. Abeta-(1-40) was incubated with equimolar GM1 at 37 degrees C. After a lag period of 6-12 h, amyloid fibrils were formed, as confirmed by circular dichroism, thioflavin-T fluorescence, size-exclusion chromatography, and transmission electron microscopy. The fibrils showed significant cytotoxicity against PC12 cells differentiated with nerve growth factor. Trisialoganglioside GT1b also facilitated the fibrillization, although the effect was weaker than that of GM1. Our study suggests an exacerbation mechanism of AD and an importance of polymorphisms in Abeta fibrils during the pathogenesis of the disease.     

Age-dependent high-density clustering of GM1 ganglioside at presynaptic neuritic terminals promotes amyloid beta-protein fibrillogenesis

The deposition of amyloid beta-protein (Abeta) is an invariable feature of Alzheimer's disease (AD); however, the biological mechanism underlying Abeta assembly into fibrils in the brain remains unclear. Here, we show that a high-density cluster of GM1 ganglioside (GM1), which was detected by the specific binding of a novel peptide (p3), appeared selectively on synaptosomes prepared from aged mouse brains. Notably, the synaptosomes bearing the high-density GM1 cluster showed extraordinary potency to induce Abeta assembly, which was suppressed by an antibody specific to GM1-bound Abeta, an endogenous seed for AD amyloid. Together with evidence that Abeta deposition starts at presynaptic terminals in the AD brain and that GM1 levels significantly increase in amyloid-positive synaptosomes prepared from the AD brain, our results suggest that the age-dependent high-density GM1 clustering at presynaptic neuritic terminals is a critical step for Abeta deposition in AD.     

X11 proteins regulate the translocation of amyloid beta-protein precursor (APP) into detergent-resistant membrane and suppress the amyloidogenic cleavage of APP by beta-site-cleaving enzyme in brain

X11 and X11-like proteins (X11L) are neuronal adaptor proteins whose association to the cytoplasmic domain of amyloid beta-protein precursor (APP) suppresses the generation of amyloid beta-protein (Abeta) implicated in Alzheimer disease pathogenesis. The amyloidogenic, but not amyloidolytic, metabolism of APP was selectively increased in the brain of mutant mice lacking X11L (Sano, Y., Syuzo-Takabatake, A., Nakaya, T., Saito, Y., Tomita, S., Itohara, S., and Suzuki, T. (2006) J. Biol. Chem. 281, 37853-37860). To reveal the actual role of X11 proteins (X11s) in suppressing amyloidogenic cleavage of APP in vivo, we generated X11 and X11L double knock-out mice and analyzed the metabolism of APP. The mutant mice showed enhanced beta-site cleavage of APP along with increased accumulation of Abeta in brain and increased colocalization of APP with beta-site APP-cleaving enzyme (BACE). In the brains of mice deficient in both X11 and X11L, the apparent relative subcellular distributions of both mature APP and its beta-C-terminal fragment were shifted toward the detergent-resistant membrane (DRM) fraction, an organelle in which BACE is active and both X11s are not nearly found. These results indicate that X11s associate primarily with APP molecules that are outside of DRM, that the dissociation of APP-X11/X11L complexes leads to entry of APP into DRM, and that cleavage of uncomplexed APP by BACE within DRM is enhanced by X11s deficiency. Present results lead to an idea that the dysfunction of X11L in the interaction with APP may recruit more APP into DRM and increase the generation of Abeta even if BACE activity did not increase in brain.     

Reduced serum level of antibodies against amyloid beta peptide is associated with aging in Tg2576 mice

Both active and passive immunization to eliminate amyloid plaques from the brain of patients with Alzheimer's disease (AD) have confirmed that amyloid beta (Abeta) vaccination does not only result in clearance of Abeta plaques but improves behavioral-cognitive deficits in animal models of AD. In the present study, the levels of naturally occurring serum antibodies against Abeta were measured in Tg2576 mice at various ages using ELISA to determine the relationship between aging and the level of anti-Abeta autoantibody. The level of anti-Abeta antibody fell significantly at the age of 9 months, at the age when amyloid plaques started to appear in the brain of Tg2576 mice, and was persistently low thereafter. However, serum immunoglobulin (Ig) level was elevated in older transgenic mice compared with younger transgenic mice suggesting that the reduced level of anti-Abeta autoantibody was not merely due to deterioration of the immune response in aged Tg2576 mice.     

Suppression of Abeta deposition in brain by peripheral administration of Fab fragments of anti-seed antibody

Assembly and deposition of amyloid beta-protein (Abeta) in the brain is a fundamental process of Alzheimer's disease (AD). We previously hypothesized that GM1 ganglioside-bound Abeta (GAbeta) is an endogenous seed for Abeta assembly in brain. Recently, we have succeeded in generation of a monoclonal antibody specific to GAbeta. Notably, this antibody, 4396C, per se substantially inhibits Abeta assembly in vitro. Here we report that the peripheral administration of Fab fragments of 4396C into transgenic mice expressing a mutant amyloid precursor protein gene, following the conjugation of the protein transduction domain of the Tat protein, markedly suppressed Abeta deposition in the brain. This result further supports our previous hypothesis and also provides a new insight into develop AD therapy through targeting seed Abeta in the brain, which selectively inhibits the initial step of the pathological process of AD.     

Vaccination with soluble Aβ oligomers generates toxicity-neutralizing antibodies

In recent studies of transgenic models of Alzheimer's disease (AD), it has been reported that antibodies to aged beta amyloid peptide 1-42 (Abeta(1-42)) solutions (mixtures of Abeta monomers, oligomers and amyloid fibrils) cause conspicuous reduction of amyloid plaques and neurological improvement. In some cases, however, neurological improvement has been independent of obvious plaque reduction, and it has been suggested that immunization might neutralize soluble, non-fibrillar forms of Abeta. It is now known that Abeta toxicity resides not only in fibrils, but also in soluble protofibrils and oligomers. The current study has investigated the immune response to low doses of Abeta(1-42) oligomers and the characteristics of the antibodies they induce. Rabbits that were injected with Abeta(1-42) solutions containing only monomers and oligomers produced antibodies that preferentially bound to assembled forms of Abeta in immunoblots and in physiological solutions. The antibodies have proven useful for assays that can detect inhibitors of oligomer formation, for immunofluorescence localization of cell-attached oligomers to receptor-like puncta, and for immunoblots that show the presence of SDS-stable oligomers in Alzheimer's brain tissue. The antibodies, moreover, were found to neutralize the toxicity of soluble oligomers in cell culture. Results support the hypothesis that immunizations of transgenic mice derive therapeutic benefit from the immuno-neutralization of soluble Abeta-derived toxins. Analogous immuno-neutralization of oligomers in humans may be a key in AD vaccines.     

Vaccination with a non-human random sequence amyloid oligomer mimic results in improved cognitive function and reduced plaque deposition and micro hemorrhage in Tg2576 mice

ABSTRACT: BACKGROUND: It is well established that vaccination of humans and transgenic animals against fibrillar amyloid beta (Abeta) prevents amyloid accumulation in plaques and preserves cognitive function in transgenic mouse models. However, autoimmune side effects have halted the development of vaccines based on full length human Abeta. Further development of an effective vaccine depends on overcoming these side effects while maintaining an effective immune response. RESULTS: We have previously reported that the immune response to amyloid oligomers is largely directed against generic epitopes that are common to amyloid oligomers of many different proteins and independent of a specific amino acid sequence. Here we have examined whether we can exploit this generic immune response to develop a vaccine that targets amyloid oligomers using a non-human random sequence amyloid oligomer. In order to study the effect of vaccination against generic oligomer epitopes, a random sequence oligomer (3A) was selected as it forms oligomers that react with the oligomer specific A11 antibody. Oligomer mimics from 3A peptide, Abeta, islet amyloid polypeptide (IAPP), and Abeta fibrils were used to vaccinate Tg2576 mice, which develop a progressive accumulation of plaques and cognitive impairment. Vaccination with the 3A random sequence antigen was just as effective as vaccination with the other antigens in improving cognitive function and reducing total plaque load (Abeta burden) in the Tg2576 mouse brains. CONCLUSION: These results show that the amyloid Abeta sequence is not necessary to produce a protective immune response that specifically targets generic amyloid oligomers. Using a non-human, random sequence antigen may facilitate the development of a vaccine that avoids autoimmune side effects.     

Novel cadherin-related membrane proteins,Alcadeins, enhance the X11-like protein-mediated stabilization of amyloid beta-protein precursor metabolism

Previously we found that X11-like protein (X11L) associates with amyloid beta-protein precursor (APP). X11L stabilizes APP metabolism and suppresses the secretion of the amyloid beta-protein (Abeta) that are the pathogenic agents of Alzheimer's disease (AD). Here we found that Alcadein (Alc), a novel membrane protein family that contains cadherin motifs and originally reported as calsyntenins, also interacted with X11L. Alc was abundant in the brain and occurred in the same areas of the brain as X11L. X11L could simultaneously associate with APP and Alc, resulting in the formation of a tripartite complex in brain. The tripartite complex stabilized intracellular APP metabolism and enhanced the X11L-mediated suppression of Abeta secretion that is due to the retardation of intracellular APP maturation. X11L and Alc also formed another complex with C99, a carboxyl-terminal fragment of APP cleaved at the beta-site (CTFbeta). The formation of the Alc.X11L.C99 complex inhibited the interaction of C99 with presenilin, which strongly suppressed the gamma-cleavage of C99. In AD patient brains, Alc and APP were particularly colocalized in dystrophic neurites in senile plaques. Deficiencies in the X11L-mediated interaction between Alc and APP and/or CTFbeta enhanced the production of Abeta, which may be related to the development or progression of AD.