Faculty Bibliography

Alzheimer's disease (AD) is the most common cause of dementia worldwide. In AD the normal soluble amyloid beta (sAbeta) peptide is converted into oligomeric/fibrillar Abeta. The oligomeric forms of Abeta are thought to be the most toxic, while fibrillar Abeta becomes deposited as amyloid plaques and congophilic angiopathy, which serve as neuropathological markers of the disease. In addition the accumulation of abnormally phosphorylated tau as soluble toxic oligomers and as neurofibrillary tangles is a critical part of the pathology. Numerous therapeutic interventions are under investigation to prevent and treat AD. Among the more exciting and advanced of these approaches is vaccination. Active and passive Immunotherapy targeting only Abeta has been successful in many AD model animal trials; however, the more limited human data has shown much less benefit so far, with encephalitis occurring in a minority of patients treated with active immunization and vasogenic edema or amyloid-related imaging abnormalities (ARIA) being a complication in some passive immunization trials. Therapeutic intervention targeting only tau has been tested only in mouse models; and no approaches targeting both pathologies concurrently has been attempted, until very recently. The immune approaches tried so far were targeting a self-protein, albeit in an abnormal conformation; however, effective enhanced clearance of the disease associated conformer has to be balanced with the potential risk of stimulating excessive toxic inflammation. The design of future more effective immunomodulatory approaches will need to target all aspects of AD pathology, as well as specifically targeting pathological oligomeric conformers, without the use of any self-antigen.

BACKGROUND: Central to the pathogenesis of Alzheimer's disease (AD) and many other neurodegenerative diseases is the conformational change of a normal self-protein into toxic oligomeric species and amyloid deposits. None of these disorders have an effective therapy, but immunization approaches hold great promise. We have previously shown that active immunization with a novel peptide when polymerized into a stable oligomeric conformation, pBri, induced a humoral immune response to toxic Abeta species in an AD model, APP/PS1 transgenic (Tg) mice, reducing plaque deposits. pBri is a glutaraldehyde polymerized form of the carboxyl fragment of an amyloidogenic protein, which is deposited in the brains of patients with a rare autosomal dominant disease due to a missense mutation in a stop codon, resulting in the translation of an intronic sequence, with no known sequence homology to any mammalian protein. METHODS: In the current study we tested whether pBri-peptide-based immunomodulation is effective at reducing both vascular amyloid deposits and tau-related pathology using TgSwDI mice with extensive congophilic angiopathy and 3xTg mice with tau pathology. RESULTS: Our results indicate that this immunomodulation approach, which produces a humoral response to proteins in a pathological conformation, is effective at reducing both Abeta and tau-related pathologies. CONCLUSIONS: This immunomodulatory approach has the advantage of using a non-self-immunogen that is less likely to be associated with autoimmune toxicity. Furthermore we found that it is able to target all the cardinal features of AD concurrently.

Background: We have shown that active immunization with a novel nonself amyloidogenic peptide (pABri) induced a humoral immune response, largely IgM, to both PHF and toxic Abeta species inAD model, APP/PS1 transgenic (Tg) mice. Histology revealed a lower amyloid burden in both the cortex and hippocampus, along with improved cognitive testing scores compared to controls. pABri immunization resulted in lower levels of soluble and insoluble Abeta42 and Abeta40 in Tg mice. Plasma from these mice was used to immunostain human AD temporal cortex brain tissue. Staining of cytoplasm and dendrites of neurons, paired helical filaments, and Abeta plaques was documented. Methods: The novel peptide, pABri, is a carboxyl fragment of an amyloidogenic protein which is deposited in the brain of patients with a rare autosomal dominant disease due to a missense mutation in a stop codon, resulting in the translation of an intronic sequence, with no known sequence homology to any mammalian protein. Hence, this immunomodulatory therapeutic is unlikely to produce autoimmune toxicity since it utilizes a non-self peptide. This current study utilizes the pABri peptide as an immunogen for active immunization in two other mouse AD Tg models: 3xTg, with tau and amyloid pathology, and TgSwDI, with extensive congophilic angiopathy. Toxicity, neuropathology, humoral immune responses, and cognitive behavior were assessed. Results: The antibodies produced are against both the primary sequence of the immunogen as well as to the pathology associated b-sheet structure that is shared by both NFTs and amyloid plaques. These conformationally specific antibodies, reacting to Abeta peptide and tau oligomers, are against a b-sheet conformation since the immunogen, pAbri, is predominantly in such a conformation. Treatment led to cognitive rescue with pABri matching cognition of WT mice. Brain homogenates revealed lower Abeta40 and Abeta42 levels in pABri treated 3xTg mice compared to controls. pABri treatment groups show lower amyloid bu!

Background: Currently there is no effective therapy for Alzheimer's Disease (AD). Active and passive immunomodulation still holds promise but current attempts only address one side of the pathology: either amyloid beta (Abeta) or the hyperphosphorylated tau (ptau) protein. Furthermore current approaches are not specific for the pathological conformers of either protein. From our novel immunization method targeting pathological beta-sheet conformation (PLoS ONE 5(10): e13391, 2010) we have developed monoclonal antibodies, some of them with promising binding capacities; and we propose to characterize a monoclonal specific for pathological conformers of Abeta and tau (TAB1) to be used for immunotherapy in AD mouse models. Methods: Monoclonal antibodies were obtained from our conformational inoculation of BALBc mice. Positive hybridomas were selected by their shared reactivity against Abeta, PHF and PrP Res. The best conformational candidate (TAB1) was selected after characterization by blots, ELISA and histology against pathological conformers in AD tissue. TAB1 is being used of treatment by intraperitoneal injection in 3xTg mice with both tau and Abeta related pathology. Results: TAB1 on tissue sections specifically immunolabels AD tissue with no labeling in young, health normal control brains. On Western blots TAB1 detects purified paired helical filament preparations, aggregated/ oligomeric Abeta and PrP Res, extracted from CJD brain tissue. Use of TAB1 therapeutically in 3xTg mice is on-going. Conclusions: We have developed a novel immunization procedure which we have used to produce monoclonal antibodies (mAbs) that recognize multiple pathological proteins, including PrP Res, oligomer A beta and ptau. We have characterized one of these mAbs, TAB1, which gives specific immunolabeling in AD tissue and onWestern blots to pathological conformers.We believe that immunotherapy that specifically targets the most toxic, oligomeric forms of Abeta and ptau, has the greatest chance of success with littl!

All prion diseases are currently without effective treatment and are universally fatal. The underlying pathogenesis of prion diseases (prionoses) is related to an autocatalytic conformational conversion of PrP(C) (C for cellular) to a pathological and infectious conformer known as PrP(Sc) (Sc for scrapie) or PrP(Res) (Res for proteinase K resistant). The past experience with variant Creutzfeldt-Jakob disease, which originated from bovine spongiform encephalopathy, as well as the ongoing epidemic of chronic wasting disease has highlighted the necessity for effective prophylactic and/or therapeutic approaches. Human prionoses are most commonly sporadic, and hence therapy is primarily directed to stop progression; however, in animals the majority of prionoses are infectious and, as a result, the emphasis is on prevention of transmission. These infectious prionoses are most commonly acquired via the alimentary tract as a major portal of infectious agent entry, making mucosal immunization a potentially attractive method to produce a local immune response that can partially or completely prevent prion entry across the gut barrier, while at the same time producing a modulated systemic immunity that is unlikely to be associated with toxicity. A critical factor in any immunomodulatory methodology that targets a self-antigen is the need to delicately balance an effective humoral immune response with potential autoimmune inflammatory toxicity. The ongoing epidemic of chronic wasting disease affecting the USA and Korea, with the potential to spread to human populations, highlights the need for such immunomodulatory approaches.

Background: Alzheimer's Disease (AD) is the most common of the conformational neurodegenerative disorders (NDD), while prion diseases are the most transmissible NDD. No highly effective treatment is currently available for any NDD. Previously, we have shown that mutated Ab peptides soluble and devoid of T-cell epitopes, produced a response which correlates with amelioration of AD pathology in animal models. Our lab has demonstrated that active immunization with antigens mimicking abnormal conformations such as polymerized ABri (pABri), could elicit antibody responses to oligomerized Ab and conformational aberrant hyperphosphorylated tau (ptau).We have now tested a combined vaccination using pBri and polymerized mutated Ab (pAb) in 3xTg mice and human PrP-Tg animals. Methods: We produced pBri and pAb1-30K18K19, which by electron microscopy formed oligomer-like structures. The pBri alone was used as an immunogen in HuPrPTg animals and in conjunction with pAb1-30KK in AD 3xTg mice using alum as an adjuvant. At the age of 15-16 months the AD mice were subjected to behavioral testing followed by histological and biochemical analysis. The HuPrPTg were assessed for the presence of antibodies against PrPRes. Results: 3xTg mice immunized animals showed no difference in locomotor activity compared to controls but a significant behavioral rescue by radial arm maze testing. The animals produced significant titers of IgM and IgG against Ab42 oligomers. Histological analysis showed a significant reduction of both amyloid and tau pathology. Biochemically, Ab42 and soluble ptau were significantly reduced. In HuPrPTg animals a systemic IgM and IgG response against PrPRes was observed, similar to the systemic response obtained in our prior successful mucosal PrP vaccinations. Conclusions: pBri conformational vaccination can be used to elicit antibodies that recognize multiple pathological proteins, including PrPRes, oligomer Ab and ptau. In 3x Tg mice with both Ab and tau pathology which were vaccinated with the combined pABri+pAb1-30KK, each of these pathologies were reduced histologically and biochemically, in association with a behavioral rescue. Such a combined approach targeting both pathological Ab and tau is more likely to be efficacious in AD patients

Background: Alzheimer's disease (AD) is the most common cause of dementia and has a major societal and economic impact. Immunomodulation has shown great promise as an AD therapy, even though the initial clinical trial was associated with severe adverse effects in a minority of patients. Our research group postulated stimulation of the innate immune system, via the Toll-like receptor 9 (TLR9), as a possible alternative method for ameliorating AD pathology, without associated toxicity. A significant concern with immunotherapy is clearance of vascular amyloid and associated microhemorrhages. This is an important issue, since cerebral amyloid angiopathy (CAA) is a common feature in AD and cognitively normal elderly individuals. We tested the efficacy of TLR9 signaling stimulation for reducing parenchymal and vascular amyloid, as well as tau related pathology. Methods: We utilized TLR9 agonist type B CpG oligonucleotides (ODNs) to stimulate innate immunity in 3xTg-AD mice, which develop both plaque and tangle pathology, and in Tg-SwDI mice with extensive CAA. Animals were divided into 2 study groups treated prior to or after the onset of AD pathology. Results: After treatment the mice were behaviorally tested. No statistical differences were observed between the groups in any of the locomotor parameters measured. CpG ODN treatment improved working memory in 3xTg-AD mice as indicated by radial arm maze testing. TLR9 stimulation was also effective at improving short-term memory in Tg-SwDI mice as evidenced by novel-object recognition testing. In 3xTg-AD mice TLR9 signaling reduced both amyloid deposits and hyperphosphorylated tau pathology. Semiquantitative analysis of hippocampal CA1 neurons revealed reduction in AT8 and PHF1 immunoreactivity in CpG ODN-treated 3xTg-AD mice. The reduction of plaque and tangle pathology was paralleled by an overall reduction in the numbers of activated microglia. There were no group differences in the levels of CNS astrocytosis; hence there was no evidence of encephalitis in the brains of treated mice. Further histological, biochemical analyses and characterization of immune responses are ongoing. Conclusions: Overall, stimulation of the TLR9 and thus innate immunity with CpG ODN (currently used in clinical trials for a variety of other diseases) represents a novel immunotherapeutic approach for AD