UB-311, a novel UBITh® amyloid β peptide vaccine for mild Alzheimer's disease

Immunomodulation induced by central nervous system-related peptides as a therapeutic strategy for neurodegenerative disorders

Neurodegenerative diseases (NDD) are disorders characterized by the progressive loss of neurons affecting motor, sensory, and/or cognitive functions. The incidence of these diseases is increasing and has a great impact due to their high morbidity and mortality. Unfortunately, current therapeutic strategies only temporarily improve the patients' quality of life but are insufficient for completely alleviating the symptoms. An interaction between the immune system and the central nervous system (CNS) is widely associated with neuronal damage in NDD. Usually, immune cell infiltration has been identified with inflammation and is considered harmful to the injured CNS. However, the immune system has a crucial role in the protection and regeneration of the injured CNS. Nowadays, there is a consensus that deregulation of immune homeostasis may represent one of the key initial steps in NDD. Dr. Michal Schwartz originally conceived the concept of "protective autoimmunity" (PA) as a well-controlled peripheral inflammatory reaction after injury, essential for neuroprotection and regeneration. Several studies suggested that immunizing with a weaker version of the neural self-antigen would generate PA without degenerative autoimmunity. The development of CNS-related peptides with immunomodulatory neuroprotective effect led to important research to evaluate their use in chronic and acute NDD. In this review, we refer to the role of PA and the potential applications of active immunization as a therapeutic option for NDD treatment. In particular, we focus on the experimental and clinical promissory findings for CNS-related peptides with beneficial immunomodulatory effects.

Amyloid-β and α-Synuclein Immunotherapy: From Experimental Studies to Clinical Trials

Alzheimer’s disease and Lewy body diseases are the most common causes of neurodegeneration and dementia. Amyloid-beta (Aβ) and alpha-synuclein (αSyn) are two key proteins involved in the pathogenesis of these neurodegenerative diseases. Immunotherapy aims to reduce the harmful effects of protein accumulation by neutralising toxic species and facilitating their removal. The results of the first immunisation trial against Aβ led to a small percentage of meningoencephalitis cases which revolutionised vaccine design, causing a shift in the field of immunotherapy from active to passive immunisation. While the vast majority of immunotherapies have been developed for Aβ and tested in Alzheimer’s disease, the field has progressed to targeting other proteins including αSyn. Despite showing some remarkable results in animal models, immunotherapies have largely failed final stages of clinical trials to date, with the exception of Aducanumab recently licenced in the US by the FDA. Neuropathological findings translate quite effectively from animal models to human trials, however, cognitive and functional outcome measures do not. The apparent lack of translation of experimental studies to clinical trials suggests that we are not obtaining a full representation of the effects of immunotherapies from animal studies. Here we provide a background understanding to the key concepts and challenges involved in therapeutic design. This review further provides a comprehensive comparison between experimental and clinical studies in Aβ and αSyn immunotherapy and aims to determine the possible reasons for the disconnection in their outcomes.

An Immunomodulatory Therapeutic Vaccine Targeting Oligomeric Amyloid-β

BACKGROUND

Aging is considered the most important risk factor for Alzheimer's disease (AD). Recent research supports the theory that immunotherapy targeting the "oligomeric" forms of amyloid-β (Aβ) may halt the progression of AD. However, previous clinical trial of the vaccine against Aβ, called AN1792, was suspended due to cases of meningoencephalitis in patients.

OBJECTIVE

To develop a peptide sensitized dendritic cells (DCs) vaccine that would target oligomer Aβ and prevent an autoimmune response.

METHODS

Double transgenic APPswe/PS1ΔE9 (Tg) and C57BL/6J control mice were used in this study. Cytokine expression profile detection, characterization of antisera, brain GSK-3β, LC3 expression, and spatial working memory testing before and post-vaccination were obtained.

RESULTS

Epitope prediction indicated that E22W42 could generate 13 new T cell epitopes which can strengthen immunity in aged subjects and silence several T cell epitopes of the wild type Aβ. The silenced T cell epitope could help avoid the autoimmune response that was seen in some patients of the AN-1792 vaccine. The E22W42 not only helped sensitize bone marrow-derived DCs for the development of an oligomeric Aβ-specific antibody, but also delayed memory impairment in the APP/PS1 mouse model. Most importantly, this E22W42 peptide will not alter the DC's natural immunomodulatory properties.

CONCLUSION

The E22W42 vaccine is possibly safer for patients with impaired immune systems. Since there is increasing evidence that oligomeric form of Aβ are the toxic species to neurons, the E22W42 antibody's specificity for these "oligomeric" Aβ species could provide the opportunity to produce some clinical benefits in AD subjects.

Immune modulations and immunotherapies for Alzheimer's disease: a comprehensive review

Alzheimer's disease (AD), the most common cause of dementia, is characterized by progressive cognitive and memory impairment ensued from neuronal dysfunction and eventual death. Intraneuronal deposition of tau proteins and extracellular senile amyloid-β plaques have ruled as the supreme postulations of AD for a relatively long time, and accordingly, a wide range of therapeutics, especially immunotherapies have been implemented. However, none of them resulted in significant positive cognitive outcomes. Especially, the repetitive failure of anti-amyloid therapies proves the inefficiency of the amyloid cascade hypothesis, suggesting that it is time to reconsider this hypothesis. Thus, for the time being, the focus is being shifted to neuroinflammation as a third core pathology in AD. Neuroinflammation was previously considered a result of the two aforementioned phenomena, but new studies suggest that it might play a causal role in the pathogenesis of AD. Neuroinflammation can act as a double-edged sword in the pathogenesis of AD, and the activation of glial cells is indispensable for mediating such attenuating or detrimental effects. The association of immune-related genes polymorphisms with the clinical phenotype of AD as well as the protective effect of anti-inflammatory drugs like nonsteroidal anti-inflammatory drugs supports the possible causal role of neuroinflammation in AD. Here, we comprehensively review immune-based therapeutic approaches toward AD, including monoclonal antibodies and vaccines. We also discuss their efficacy and underlying reasons for shortcomings. Lastly, we highlight the capacity of modulating the neuroimmune interactions and targeting neuroinflammation as a promising opportunity for finding optimal treatments for AD.

Immunotherapeutics for AD: A Work in Progress

Alzheimer's Disease (AD), often called the 'Plague of the 21st Century,' is a progressive, irreversible neurodegenerative disorder that leads to the degeneration and death of neurons. Multiple factors, such as genetic defects, epigenetic regulations, environmental factors, or cerebrovascular damage, are a manifestation of the neurodegenerative process that begins to occur decades before the onset of disease. To date, no treatment or therapeutic strategy has proven to be potent in inhibiting its progress or reversing the effects of the disease. The ever-increasing numbers and lack of sufficient therapies that can control or reverse the effects of the disease have propelled research in the direction of devising efficient therapeutic strategies for AD. This review comprehensively discusses the active and passive immunotherapies against Amyloid-β and Tau protein, which remain the popular choice of targets for AD therapeutics. Some of the prospective immunotherapies against Aβ plaques have failed due to various reasons. Much of the research is focused on targeting Tau, specifically, targeting the mid-region of extracellular Tau due to their potential to prevent seeding and hence the spread of neurofibrillary tangles (NFTs). Thus, there is a need to thoroughly understand the disease onset mechanisms and discover effective therapeutic strategies.

Therapeutic Advances in Diabetes, Autoimmune, and Neurological Diseases

Since 2015, 170 small molecules, 60 antibody-based entities, 12 peptides, and 15 gene- or cell-therapies have been approved by FDA for diverse disease indications. Recent advancement in medicine is facilitated by identification of new targets and mechanisms of actions, advancement in discovery and development platforms, and the emergence of novel technologies. Early disease detection, precision intervention, and personalized treatments have revolutionized patient care in the last decade. In this review, we provide a comprehensive overview of current and emerging therapeutic modalities developed in the recent years. We focus on nine diseases in three major therapeutics areas, diabetes, autoimmune, and neurological disorders. The pathogenesis of each disease at physiological and molecular levels is discussed and recently approved drugs as well as drugs in the clinic are presented.

Sexual Dimorphism in the 3xTg-AD Mouse Model and Its Impact on Pre-Clinical Research

Female sex is a leading risk factor for developing Alzheimer’s disease (AD). Sexual dimorphism in AD is gaining attention as clinical data show that women are not only more likely to develop AD but also to experience worse pathology and faster cognitive decline. Pre-clinical AD research in animal models often neglects to address sexual dimorphism in evaluation of behavioral or molecular characteristics and outcomes. This can compromise its translation to a clinical setting. The triple-transgenic AD mouse model (3xTg-AD) is a commonly used but unique AD model because it exhibits both amyloid and tau pathology, essential features of the human AD phenotype. Mounting evidence has revealed important sexually dimorphic characteristics of this animal model that have yet to be reviewed and thus, are often overlooked in studies using the 3xTg-AD model. In this review we conduct a thorough analysis of reports of sexual dimorphism in the 3xTg-AD model including findings of molecular, behavioral, and longevity-related sex differences in original research articles through August 2020. Importantly, we find results to be inconsistent, and that strain source and differing methodologies are major contributors to lack of consensus regarding traits of each sex. We first touch on the nature of sexual dimorphism in clinical AD, followed by a brief summary of sexual dimorphism in other major AD murine models before discussing the 3xTg-AD model in depth. We conclude by offering four suggestions to help unify pre-clinical mouse model AD research inspired by the NIH expectations for considering sex as a biological variable.

Alzheimer Disease Clinical Trials Targeting Amyloid: Lessons Learned From Success in Mice and Failure in Humans

BACKGROUND

The goal of slowing or halting the development of Alzheimer disease (AD) has resulted in the huge allocation of resources by academic institutions and pharmaceutical companies to the development of new treatments. The etiology of AD is elusive, but the aggregation of amyloid-β and tau peptide and oxidative processes are considered critical pathologic mechanisms. The failure of drugs with multiple mechanisms to meet efficacy outcomes has caused several companies to decide not to pursue further AD studies and has left the field essentially where it has been for the past 15 years. Efforts are underway to develop biomarkers for detection and monitoring of AD using genetic, imaging, and biochemical technology, but this is of minimal use if no intervention can be offered.

REVIEW SUMMARY

In this review, we consider the natural progression of AD and how it continues despite present attempts to modify the amyloid-related machinery to alter the disease trajectory. We describe the mechanisms and approaches to AD treatment targeting amyloid, including both passive and active immunotherapy as well as inhibitors of enzymes in the amyloidogenic pathway.

CONCLUSION

Lessons learned from clinical trials of amyloid reduction strategies may prove crucial for the leap forward toward novel therapeutic targets to treat AD.

Amyloid Oligomers: A Joint Experimental/Computational Perspective on Alzheimer's Disease, Parkinson's Disease, Type II Diabetes, and Amyotrophic Lateral Sclerosis

Protein misfolding and aggregation is observed in many amyloidogenic diseases affecting either the central nervous system or a variety of peripheral tissues. Structural and dynamic characterization of all species along the pathways from monomers to fibrils is challenging by experimental and computational means because they involve intrinsically disordered proteins in most diseases. Yet understanding how amyloid species become toxic is the challenge in developing a treatment for these diseases. Here we review what computer, in vitro, in vivo, and pharmacological experiments tell us about the accumulation and deposition of the oligomers of the (Aβ, tau), α-synuclein, IAPP, and superoxide dismutase 1 proteins, which have been the mainstream concept underlying Alzheimer's disease (AD), Parkinson's disease (PD), type II diabetes (T2D), and amyotrophic lateral sclerosis (ALS) research, respectively, for many years.

Targeting for Success: Demonstrating Proof-of-Concept with Mechanistic Early Phase Clinical Pharmacology Studies for Disease-Modification in Neurodegenerative Disorders

The clinical failure rate for disease-modifying treatments (DMTs) that slow or stop disease progression has been nearly 100% for the major neurodegenerative disorders (NDDs), with many compounds failing in expensive and time-consuming phase 2 and 3 trials for lack of efficacy. Here, we critically review the use of pharmacological and mechanistic biomarkers in early phase clinical trials of DMTs in NDDs, and propose a roadmap for providing early proof-of-concept to increase R&D productivity in this field of high unmet medical need. A literature search was performed on published early phase clinical trials aimed at the evaluation of NDD DMT compounds using MESH terms in PubMed. Publications were selected that reported an early phase clinical trial with NDD DMT compounds between 2010 and November 2020. Attention was given to the reported use of pharmacodynamic (mechanistic and physiological response) biomarkers. A total of 121 early phase clinical trials were identified, of which 89 trials (74%) incorporated one or multiple pharmacodynamic biomarkers. However, only 65 trials (54%) used mechanistic (target occupancy or activation) biomarkers to demonstrate target engagement in humans. The most important categories of early phase mechanistic and response biomarkers are discussed and a roadmap for incorporation of a robust biomarker strategy for early phase NDD DMT clinical trials is proposed. As our understanding of NDDs is improving, there is a rise in potentially disease-modifying treatments being brought to the clinic. Further increasing the rational use of mechanistic biomarkers in early phase trials for these (targeted) therapies can increase R&D productivity with a quick win/fast fail approach in an area that has seen a nearly 100% failure rate to date.

Emerging Promise of Immunotherapy for Alzheimer's Disease: A New Hope for the Development of Alzheimer's Vaccine

BACKGROUND

Alzheimer's disease (AD) is a chronic neurodegenerative disorder and the characteristics of this devastating disorder include the progressive and disabling deficits in the cognitive functions including reasoning, attention, judgment, comprehension, memory, and language.

OBJECTIVE

In this article, we have focused on the recent progress that has been achieved in the development of an effective AD vaccine.

SUMMARY

Currently, available treatment options of AD are limited to deliver short-term symptomatic relief only. A number of strategies targeting amyloid-beta (Aβ) have been developed in order to treat or prevent AD. In order to exert an effective immune response, an AD vaccine should contain adjuvants that can induce an effective anti-inflammatory T helper 2 (Th2) immune response. AD vaccines should also possess the immunogens which have the capacity to stimulate a protective immune response against various cytotoxic Aβ conformers. The induction of an effective vaccine's immune response would necessitate the parallel delivery of immunogen to dendritic cells (DCs) and their priming to stimulate a Th2-polarized response. The aforesaid immune response is likely to mediate the generation of neutralizing antibodies against the neurotoxic Aβ oligomers (AβOs) and also anti-inflammatory cytokines, thus preventing the AD-related inflammation.

CONCLUSION

Since there is an age-related decline in the immune functions, therefore vaccines are more likely to prevent AD instead of providing treatment. AD vaccines might be an effective and convenient approach to avoid the treatment-related huge expense.

Advances in Drug Therapy for Alzheimer's Disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease that mainly causes dementia. It is a serious threat to the health of the global elderly population. Considerable money and effort has been invested in the development of drug therapy for AD worldwide. Many drug therapies are currently under development or in clinical trials, based on two known mechanisms of AD, namely, Aβ toxicity and the abnormal Tau hyperphosphorylation. Numerous drugs are also being developed for other AD associated mechanisms such as neuroinflammation, neurotransmitter imbalance, oxidative damage and mitochondrial dysfunction, neuron loss and degeneration. Even so, the number of drugs that can successfully improve symptoms or delay the progression of the disease remains very limited. However, multi-drug combinations may provide a new avenue for drug therapy for AD. In addition, early diagnosis of AD and timely initiation of treatment may allow drugs that act on the early pathological processes of AD to help improve the symptoms and prevent the progression of the condition.

Changes in the brain transcriptome after DNA Aβ42 trimer immunization in a 3xTg-AD mouse model

Alzheimer's disease (AD) has been associated with accumulation of amyloid beta (Aβ) peptides in brain, and immunotherapy targeting Aβ provides potential for AD prevention. We have used a DNA Aβ42 trimer construct for immunization of 3xTg-AD mice and found previously significant reduction of amyloid and tau pathology due to the immunotherapy. We show here that DNA Aβ42 immunized 3xTg-AD mice showed better performance in nest building activities and had a higher 24 months survival rate compared to the non-treated AD controls. The analysis of differently expressed genes in brains from 24 months old mice showed significant increases transcript levels between non-immunized AD mice and wild-type controls for genes involved in microglia and astrocyte function, cytokine and inflammatory signaling, apoptosis, the innate and adaptive immune response and are consistent with an inflammatory phenotype in AD. Most of these upregulated genes were downregulated in the DNA Aβ42 immunized 3xTg-AD mice due to the vaccine. Transcript numbers for the immediate early genes, Arc, Bdnf, Homer1, Egr1 and cfos, involved in neuronal and neurotransmission pathways which were much lower in the non-immunized 3xTg-AD mice, were restored to wild-type mouse brain levels in DNA Aβ42 immunized 3xTg-AD mice indicating positive effects of DNA Aβ42 immunotherapy on synapse stability and plasticity. The immune response after immunization is complex, but the multitude of changes after DNA Aβ42 immunization shows that this response moves beyond the amyloid hypothesis and into direction of disease prevention.

Novel antibodies detect additional α-synuclein pathology in synucleinopathies: potential development for immunotherapy

BACKGROUND

Alpha-synuclein (α-Syn) aggregation is the primary characteristic of synucleinopathies including Parkinson's disease (PD), dementia with Lewy bodies (DLB) and multiple system atrophy (MSA). Immunotherapy targeting α-Syn has shown promising results in animal models of the disease. This study investigates the target specificity of three different active vaccines for pathological α-Syn aggregates found in human brain tissue from synucleinopathies.

METHODS

Guinea pigs were immunised with 3 vaccines developed by United Neuroscience, and IgG fractions purified from the resulting immune sera (IGG-1, IGG-2 or IGG-3) were used to perform immunohistochemical staining of human cases of PD, DLB and MSA. The resulting immunoreactivity was compared to a commercially available α-Syn antibody from Novacastra (NOV) commonly used for diagnostic purposes. Images were captured from the substantia nigra (SN), temporal lobe, internal capsule, insular cortex and putamen and quantified for the percentage area with α-Syn immunoreactivity. Lewy bodies (LB) and Lewy neurites (LN) were further analysed in PD and DLB cases.

RESULTS

Vaccine-generated antibodies detected more α-Syn pathology compared to NOV. The levels of α-Syn immunoreactivity varied between brain region and disease type with IGG-3 recognising the highest levels of α-Syn in most cases and in all brain regions that are affected early in disease progression. IGG-3 had a high recognition for glial inclusions found in MSA which are known to have a more compact conformation. Slot blot analysis confirmed the specificity of IGG-3 for native oligomers and fibrillar α-Syn. Higher levels of α-Syn were recognised by IGG-2 in cortical regions, and by IGG-3 in SN of PD and DLB cases. This was due to increased immunolabelling of LNs in these brain regions suggesting that IGG-2 and IGG-3 recognised additional α-Syn pathology compared to IGG-1 and NOV. Whether the unique binding properties of the antibodies produced in guinea pigs will translate in the clinic remains to be addressed, which is the main limitation of this study.

CONCLUSIONS

These vaccines induce antibodies that bind α-Syn oligomers and aggregates in the human brain and specifically support the choice of the vaccine generating IGG-3 (i.e. UB-312) as a candidate for clinical trials for synucleinopathies.

A Chronological Review of Potential Disease-Modifying Therapeutic Strategies for Alzheimer's Disease

Late-onset Alzheimer's disease (LOAD) is a neurodegenerative disorder that has become a worldwide health problem. This pathology has been classically characterized for its affectation on cognitive function and the presence of depositions of extracellular amyloid β-protein (Aβ) and intracellular neurofibrillary tangles (NFT) composed of hyperphosphorylated Tau protein. To this day, no effective treatment has been developed. Multiple strategies have been proposed over the years with the aim of finding new therapeutic approaches, such as the sequestration of Aβ in plasma or the administration of anti-inflammatory drugs. Also, given the significant role of the insulin receptor in the brain in the proper maintenance of cognitive function, drugs focused on the amelioration of insulin resistance have been proposed as potentially useful and effective in the treatment of AD. In the present review, taking into account the molecular complexity of the disease, it has been proposed that the most appropriate therapeutic strategy is a combinatory treatment of several drugs that will regulate a wide spectrum of the described altered pathological pathways.

Therapeutic Strategies to Reduce the Toxicity of Misfolded Protein Oligomers

The aberrant aggregation of proteins is implicated in the onset and pathogenesis of a wide range of neurodegenerative disorders, including Alzheimer’s and Parkinson’s diseases. Mounting evidence indicates that misfolded protein oligomers produced as intermediates in the aggregation process are potent neurotoxic agents in these diseases. Because of the transient and heterogeneous nature of these elusive aggregates, however, it has proven challenging to develop therapeutics that can effectively target them. Here, we review approaches aimed at reducing oligomer toxicity, including (1) modulating the oligomer populations (e.g., by altering the kinetics of aggregation by inhibiting, enhancing, or redirecting the process), (2) modulating the oligomer properties (e.g., through the size–hydrophobicity–toxicity relationship), (3) modulating the oligomer interactions (e.g., by protecting cell membranes by displacing oligomers), and (4) reducing oligomer toxicity by potentiating the protein homeostasis system. We analyze examples of these complementary approaches, which may lead to the development of compounds capable of preventing or treating neurodegenerative disorders associated with protein aggregation.

Active immunotherapy and alternative therapeutic modalities for Alzheimer's disease

As knowledge of Alzheimer's disease (AD) progression improves, the field has recognized the need to diversify the pipeline, broaden strategies and approaches to therapies, as well as delivery mechanisms. A better understanding of the earliest biological processes of AD/dementia would help inform drug target selection. Currently there are a number of programs exploring these alternate avenues. This meeting will allow experts in the field (academia, industry, government) to provide perspectives and experiences that can help elucidate what the pipeline looks like today and what avenues hold promise in developing new therapies across the stages of AD. The focus here is on Active Immunotherapies and Alternative Therapeutic Modalities. This topic includes active vaccines, antisense oligomers, and cell-based therapy among others, and highlights new clinical developments that utilize these modalities.

Oral Immunization with Soybean Storage Protein Containing Amyloid-β 4-10 Prevents Spatial Learning Decline

 Amyloid-β (Aβ) plays a central role in the pathogenesis of Alzheimer’s disease (AD). Because AD pathologies begin two decades before the onset of dementia, prevention of Aβ amyloidosis has been proposed as a mean to block the pathological cascade. Here, we generate a transgenic plant-based vaccine, a soybean storage protein containing Aβ4–10, named Aβ+, for oral Aβ immunization. One mg of Aβ+ or control protein (Aβ–) was administered to TgCRND8 mice once a week from 9 weeks up to 58 weeks. Aβ+ immunization raised both anti-Aβ antibodies and cellular immune responses. Spatial learning decline was prevented in the Aβ+ immunized group in an extended reference memory version of Morris water maze test from 21 to 57 weeks. In Tris-buffered saline (TBS), sodium dodecyl sulfate (SDS), and formic acid (FA) serial extractions, all sets of Aβ species from Aβ monomer, low to high molecular weight Aβ oligomers, and Aβ smears had different solubility in TgCRND8 brains. Aβ oligomers decreased in TBS fractions, corresponding to an increase in high molecular weight Aβ oligomers in SDS extracts and Aβ smears in FA fraction of the Aβ+ treated group. There was significant inhibition of histological Aβ burden, especially in diffuse plaques, and suppression of microglial inflammation. Processing of amyloid-β protein precursor was not different between Aβ+ and Aβ– groups. No evidence of amyloid-related inflammatory angiopathy was observed. Thus, Aβ+ oral immunization could be a promising, cheap, and long-term safe disease-modifying therapy to prevent the pathological process in AD.

Therapeutic Strategies Targeting Amyloid-β in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder linked to protein misfolding and aggregation. AD is pathologically characterized by senile plaques formed by extracellular Amyloid-β (Aβ) peptide and Intracellular Neurofibrillary Tangles (NFT) formed by hyperphosphorylated tau protein. Extensive synaptic loss and neuronal degeneration are responsible for memory impairment, cognitive decline and behavioral dysfunctions typical of AD. Amyloidosis has been implicated in the depression of acetylcholine synthesis and release, overactivation of N-methyl-D-aspartate (NMDA) receptors and increased intracellular calcium levels that result in excitotoxic neuronal degeneration. Current drugs used in AD treatment are either cholinesterase inhibitors or NMDA receptor antagonists; however, they provide only symptomatic relief and do not alter the progression of the disease. Aβ is the product of Amyloid Precursor Protein (APP) processing after successive cleavage by β- and γ-secretases while APP proteolysis by α-secretase results in non-amyloidogenic products. According to the amyloid cascade hypothesis, Aβ dyshomeostasis results in the accumulation and aggregation of Aβ into soluble oligomers and insoluble fibrils. The former are synaptotoxic and can induce tau hyperphosphorylation while the latter deposit in senile plaques and elicit proinflammatory responses, contributing to oxidative stress, neuronal degeneration and neuroinflammation. Aβ-protein-targeted therapeutic strategies are thus a promising disease-modifying approach for the treatment and prevention of AD. This review summarizes recent findings on Aβ-protein targeted AD drugs, including β-secretase inhibitors, γ-secretase inhibitors and modulators, α-secretase activators, direct inhibitors of Aβ aggregation and immunotherapy targeting Aβ, focusing mainly on those currently under clinical trials.

Vaccination Prevented Short-Term Memory Loss, but Deteriorated Long-Term Spatial Memory in Alzheimer's Disease Mice, Independent of Amyloid-β Pathology

Background:

Soluble oligomeric amyloid-β (Aβ), rather than Aβ plaques, seems to be the culprit in Alzheimer’s disease (AD). Accordingly, a new concept vaccine of small cyclic peptide conjugates, selectively targeting oligomeric Aβ, has been developed.

Objective:

Study the therapeutic potential of this new vaccine in a mouse model for AD.

Methods:

J20 mice, overexpressing human amyloid precursor protein, were validated for an AD-like phenotype. Then, J20 mice were vaccinated at 2, 3, and 4 months of age and AD phenotype was evaluated at 6, 9, and 12 months of age; or at 9, 10, and 11 months with evaluation at 12 months. Effects on Aβ pathology were studied by plaque load (immunohistochemistry; 6E10) and antibody titers against Aβ (ELISA). AD behavioral phenotype was evaluated by performance in a battery of cognitive tests.

Results:

J20 mice displayed age-related Aβ plaque development and an AD-like behavioral phenotype. A consistent antibody response to the cyclic peptides was, however, not extended to Aβ, leaving plaque load unaffected. Nevertheless, immunization at young ages prevented working- and short-term spatial memory loss, but deteriorated long-term spatial learning and memory, at 12 months of age. Immunization at later ages did not affect any measured parameter.

Conclusion:

J20 mice provide a relevant model for AD to study potential anti-Aβ treatment. Early vaccination prevented short-term memory loss at later ages, but deteriorated long-term spatial memory, however without affecting Aβ pathology. Later vaccination had no effects, but optimal timing may require further investigation.

Immunotherapies for Aging-Related Neurodegenerative Diseases-Emerging Perspectives and New Targets

Neurological disorders such as Alzheimer's disease (AD), Lewy body dementia (LBD), frontotemporal dementia (FTD), and vascular dementia (VCID) have no disease-modifying treatments to date and now constitute a dementia crisis that affects 5 million in the USA and over 50 million worldwide. The most common pathological hallmark of these age-related neurodegenerative diseases is the accumulation of specific proteins, including amyloid beta (Aβ), tau, α-synuclein (α-syn), TAR DNA-binding protein 43 (TDP43), and repeat-associated non-ATG (RAN) peptides, in the intra- and extracellular spaces of selected brain regions. Whereas it remains controversial whether these accumulations are pathogenic or merely a byproduct of disease, the majority of therapeutic research has focused on clearing protein aggregates. Immunotherapies have garnered particular attention for their ability to target specific protein strains and conformations as well as promote clearance. Immunotherapies can also be neuroprotective: by neutralizing extracellular protein aggregates, they reduce spread, synaptic damage, and neuroinflammation. This review will briefly examine the current state of research in immunotherapies against the 3 most commonly targeted proteins for age-related neurodegenerative disease: Aβ, tau, and α-syn. The discussion will then turn to combinatorial strategies that enhance the effects of immunotherapy against aggregating protein, followed by new potential targets of immunotherapy such as aging-related processes.

Characterization and preclinical evaluation of the cGMP grade DNA based vaccine, AV-1959D to enter the first-in-human clinical trials

The DNA vaccine, AV-1959D, targeting N-terminal epitope of Aβ peptide, has been proven immunogenic in mice, rabbits, and non-human primates, while its therapeutic efficacy has been shown in mouse models of Alzheimer's disease (AD). Here we report for the first time on IND-enabling biodistribution and safety/toxicology studies of cGMP-grade AV-1959D vaccine in the Tg2576 mouse model of AD. We also tested acute neuropathology safety profiles of AV-1959D in another AD disease model, Tg-SwDI mice with established vascular and parenchymal Aβ pathology in a pre-clinical translational study. Biodistribution studies two days after the injection demonstrated high copy numbers of AV-1959D plasmid after single immunization of Tg2576 mice at the injection sites but not in the tissues of distant organs. Plasmids persisted at the injection sites of some mice 60 days after vaccination. In Tg2576 mice with established amyloid pathology, we did not observe short- or long-term toxicities after multiple immunizations with three doses of AV-1959D. Assessment of the repeated dose acute safety of AV-1959D in cerebral amyloid angiopathy (CAA) prone Tg-SwDI mice did not reveal any immunotherapy-induced vasogenic edema detected by magnetic resonance imaging (MRI) or increased microhemorrhages. Multiple immunizations of Tg-SwDI mice with AV-1959D did not induce T and B cell infiltration, glial activation, vascular deposition of Aβ, or neuronal degeneration (necrosis and apoptosis) greater than that in the control group determined by immunohistochemistry of brain tissues. Taken together, the safety data from two different mouse models of AD substantiate a favorable safety profile of the cGMP grade AV-1959D vaccine supporting its progression to first-in-human clinical trials.

Peptide-Based Vaccines: Current Progress and Future Challenges

Vaccines have had a profound impact on the management and prevention of infectious disease. In addition, the development of vaccines against chronic diseases has attracted considerable interest as an approach to prevent, rather than treat, conditions such as cancer, Alzheimer's disease, and others. Subunit vaccines consist of nongenetic components of the infectious agent or disease-related epitope. In this Review, we discuss peptide-based vaccines and their potential in three therapeutic areas: infectious disease, Alzheimer's disease, and cancer. We discuss factors that contribute to vaccine efficacy and how these parameters may potentially be modulated by design. We examine both clinically tested vaccines as well as nascent approaches and explore current challenges and potential remedies. While peptide vaccines hold substantial promise in the prevention of human disease, many obstacles remain that have hampered their clinical use; thus, continued research efforts to address these challenges are warranted.

The Impact of Natural Compounds on S-Shaped Aβ42 Fibril: From Molecular Docking to Biophysical Characterization

The pursuit for effective strategies inhibiting the amyloidogenic process in neurodegenerative disorders, such as Alzheimer’s disease (AD), remains one of the main unsolved issues, and only a few drugs have demonstrated to delay the degeneration of the cognitive system. Moreover, most therapies induce severe side effects and are not effective at all stages of the illness. The need to find novel and reliable drugs appears therefore of primary importance. In this context, natural compounds have shown interesting beneficial effects on the onset and progression of neurodegenerative diseases, exhibiting a great inhibitory activity on the formation of amyloid aggregates and proving to be effective in many preclinical and clinical studies. However, their inhibitory mechanism is still unclear. In this work, ensemble docking and molecular dynamics simulations on S-shaped Aβ₄₂ fibrils have been carried out to evaluate the influence of several natural compounds on amyloid conformational behaviour. A deep understanding of the interaction mechanisms between natural compounds and Aβ aggregates may play a key role to pave the way for design, discovery and optimization strategies toward an efficient destabilization of toxic amyloid assemblies.

Rationale for the development of an Alzheimer's disease vaccine

Vaccination traditionally has targeted infectious agents and thus has not heretofore been used to prevent neurodegenerative illness. However, amyloid β (Aβ) or tau, which can act like infectious proteins, or prions, might induce Alzheimer's disease (AD). Furthermore, evidence suggests that traditional infectious agents, including certain viruses and bacteria, may trigger AD. It is therefore worth exploring whether removing such targets could prevent AD. Although failing to treat AD patients who already display cognitive impairment, Aβ monoclonal antibodies are being tested in pre-symptomatic, at-risk individuals to prevent dementia. These antibodies might become the first AD therapeutics. However, their high cost will keep them out of the arms of the vast majority of patients, who increasingly live in developing countries. Because vaccines produce antibodies internally at much lower cost, vaccination might be the most promising approach to reducing the global burden of dementia.

Current and Future Treatments in Alzheimer Disease: An Update

Disease-modifying treatment strategies for Alzheimer disease (AD) are still under extensive research. Nowadays, only symptomatic treatments exist for this disease, all trying to counterbalance the neurotransmitter disturbance: 3 cholinesterase inhibitors and memantine. To block the progression of the disease, therapeutic agents are supposed to interfere with the pathogenic steps responsible for the clinical symptoms, classically including the deposition of extracellular amyloid β plaques and intracellular neurofibrillary tangle formation. Other underlying mechanisms are targeted by neuroprotective, anti-inflammatory, growth factor promotive, metabolic efficacious agents and stem cell therapies. Recent therapies have integrated multiple new features such as novel biomarkers, new neuropsychological outcomes, enrollment of earlier populations in the course of the disease, and innovative trial designs. In the near future different specific agents for every patient might be used in a “precision medicine” context, where aberrant biomarkers accompanied with a particular pattern of neuropsychological and neuroimaging findings could determine a specific treatment regimen within a customized therapeutic framework. In this review, we discuss potential disease-modifying therapies that are currently being studied and potential individualized therapeutic frameworks that can be proved beneficial for patients with AD.

Novel approaches to counter protein aggregation pathology in Parkinson's disease

The primary neuropathological characteristics of the Parkinsonian brain are the loss of nigral dopamine neurons and the aggregation of alpha synuclein protein. Efforts to development potentially disease-modifying treatments have largely focused on correcting these aspects of the condition. In the last decade treatments targeting protein aggregation have entered the clinical pipeline. In this chapter we provide an overview of ongoing clinical trial programs for different therapies attempting to reduce protein aggregation pathology in Parkinson's disease. We will also briefly consider various novel approaches being proposed-and being developed preclinically-to inhibit/reduce aggregated protein pathology in Parkinson's.

Plasma amyloid assay as a pre-screening tool for amyloid positron emission tomography imaging in early stage Alzheimer's disease

INTRODUCTION

Due to the high cost and high failure rate of ascertaining amyloid positron emission tomography positivity (PET+) in patients with earlier stage Alzheimer's disease (AD), an effective pre-screening tool for amyloid PET scans is needed.

METHODS

Patients with mild cognitive impairment (n = 33, 24.2% PET+, 42% females, age 74.4 ± 7.5, MMSE 26.8 ± 1.9) and mild dementia (n = 19, 63.6% PET+, 36.3% females, age 73.0 ± 9.3, MMSE 22.6 ± 2.0) were recruited. Amyloid PET imaging, Apolipoprotein E (APOE) genotyping, and plasma amyloid β (Aβ)_1-40, Aβ_1-42, and total tau protein quantification by immunomagnetic reduction (IMR) method were performed. Receiver operating characteristics (ROC) analysis and Youden's index were performed to identify possible cut-off points, clinical sensitivities/specificities, and areas under the curve (AUCs).

RESULTS

Amyloid PET+ participants had lower plasma Aβ_1-42 levels than amyloid PET-negative (PET-) subjects. APOE ε4 carriers had higher plasma Aβ_1-42 than non-carriers. We developed an algorithm involving the combination of plasma Aβ_1-42 and APOE genotyping. The success rate for detecting amyloid PET+ patients effectively increased from 42.3 to 70.4% among clinically suspected MCI and mild dementia patients.

CONCLUSIONS

Our results demonstrate the possibility of utilizing APOE genotypes in combination with plasma Aβ_1-42 levels as a pre-screening tool for predicting the positivity of amyloid PET findings in early stage dementia patients.

Testing a MultiTEP-based combination vaccine to reduce Aβ and tau pathology in Tau22/5xFAD bigenic mice

BACKGROUND

Alzheimer disease (AD) is characterized by the accumulation of beta-amyloid (Aβ) plaques and neurofibrillary tangles composed of hyperphosphorylated tau, which together lead to neurodegeneration and cognitive decline. Current therapeutic approaches have primarily aimed to reduce pathological aggregates of either Aβ or tau, yet phase 3 clinical trials of these approaches have thus far failed to delay disease progression in humans. Strong preclinical evidence indicates that these two abnormally aggregated proteins interact synergistically to drive downstream neurodegeneration. Therefore, combinatorial therapies that concurrently target both Aβ and tau might be needed for effective disease modification.

METHODS

A combinatorial vaccination approach was designed to concurrently target both Aβ and tau pathologies. Tau22/5xFAD (T5x) bigenic mice that develop both pathological Aβ and tau aggregates were injected intramuscularly with a mixture of two MultiTEP epitope vaccines: AV-1959R and AV-1980R, targeting Aβ and tau, respectively, and formulated in AdvaxCpG, a potent polysaccharide adjuvant. Antibody responses of vaccinated animals were measured by ELISA, and neuropathological changes were determined in brain homogenates of vaccinated and control mice using ELISA and Meso Scale Discovery (MSD) multiplex assays.

RESULTS

T5x mice immunized with a mixture of Aβ- and tau-targeting vaccines generated high Aβ- and tau-specific antibody titers that recognized senile plaques and neurofibrillary tangles/neuropil threads in human AD brain sections. Production of these antibodies in turn led to significant reductions in the levels of soluble and insoluble total tau, and hyperphosphorylated tau as well as insoluble Aβ42, within the brains of bigenic T5x mice.

CONCLUSIONS

AV-1959R and AV-1980R formulated with AdvaxCpG adjuvant are immunogenic and therapeutically potent vaccines that in combination can effectively reduce both of the hallmark pathologies of AD in bigenic mice. Taken together, these findings warrant further development of this vaccine technology for ultimate testing in human AD.

AJP001, a novel helper T-cell epitope, induces a humoral immune response with activation of innate immunity when included in a peptide vaccine

Vaccine design requires well-tailored formulations including a T-cell epitope and adjuvants. We identified a novel cationic peptide, AJP001, which possesses a strong affinity for murine MHC class II alleles (H2-IEd and H2-IAd) and low affinity for H2-IAb. We designed an AJP001 and epitope peptide-conjugated vaccine, AJP001-angiotensin (Ang) II, which was intracutaneously administered to mice three times at 2-week intervals. Indeed, the AJP001-Ang II vaccine induced antibody production against Ang II in BALB/cA mice but not in C57BL/6 mice. To estimate the T-cell-dependent immunogenicity of the AJP001 conjugate vaccine in human cells, naïve human peripheral blood mononuclear cells (PBMCs) were exposed to AJP001-Ang II, and T-cell proliferation was evaluated by analyzing cell division using flow cytometric measurement of carboxyfluorescein succinimidyl ester (CFSE) dye dilution. To activate the immune response, the innate immune system must be activated by adjuvant treatment. Interestingly, treatment with AJP001 induced IL-1β and IL-18 secretion via NLRP3 inflammasome activation and induced TNF-α and IL-6 production through an NF-κB-dependent pathway in human and mouse macrophages. These results suggest that AJP001 behaves as a T-cell epitope in mice and humans and is a useful tool for the formulation of peptide vaccines without the addition of adjuvants.

Modulation of Amyloid-β42 Conformation by Small Molecules Through Nonspecific Binding

Aggregation of amyloid-β (Aβ) peptides is a crucial step in the progression of Alzheimer's disease (AD). Identifying aggregation inhibitors against AD has been a great challenge. We report an atomistic simulation study of the inhibition mechanism of two small molecules, homotaurine and scyllo-inositol, which are AD drug candidates currently under investigation. We show that both small molecules promote a conformational change of the Aβ42 monomer toward a more collapsed phase through a nonspecific binding mechanism. This finding provides atomistic-level insights into designing potential drug candidates for future AD treatments.

Neuroprotective Approach of Anti-Cancer Microtubule Stabilizers Against Tauopathy Associated Dementia: Current Status of Clinical and Preclinical Findings

Neuronal microtubule (MT) tau protein provides cytoskeleton to neuronal cells and plays a vital role including maintenance of cell shape, intracellular transport, and cell division. Tau hyperphosphorylation mediates MT destabilization resulting in axonopathy and neurotransmitter deficit, and ultimately causing Alzheimer’s disease (AD), a dementing disorder affecting vast geriatric populations worldwide, characterized by the existence of extracellular amyloid plaques and intracellular neurofibrillary tangles in a hyperphosphorylated state. Pre-clinically, streptozotocin stereotaxically mimics the behavioral and biochemical alterations similar to AD associated with tau pathology resulting in MT assembly defects, which proceed neuropathological cascades. Accessible interventions like cholinesterase inhibitors and NMDA antagonist clinically provides only symptomatic relief. Involvement of microtubule stabilizers (MTS) prevents tauopathy particularly by targeting MT oriented cytoskeleton and promotes polymerization of tubulin protein. Multiple in vitro and in vivo research studies have shown that MTS can hold substantial potential for the treatment of AD-related tauopathy dementias through restoration of tau function and axonal transport. Moreover, anti-cancer taxane derivatives and epothiolones may have potential to ameliorate MT destabilization and prevent the neuronal structural and functional alterations associated with tauopathies. Therefore, this current review strictly focuses on exploration of various clinical and pre-clinical features available for AD to understand the neuropathological mechanisms as well as introduce pharmacological interventions associated with MT stabilization. MTS from diverse natural sources continue to be of value in the treatment of cancer, suggesting that these agents have potential to be of interest in the treatment of AD-related tauopathy dementia in the future.

A brief history of antibody-based therapy

Active and passive immunization have been used to treat human disease for hundreds of years and improvements in technology and knowledge is only increasing the number of therapeutic applications. The current and future use of immunization to treat neurodegenerative diseases are briefly described herein to serve as an introduction to this special issue.

Promising Results from Alzheimer's Disease Passive Immunotherapy Support the Development of a Preventive Vaccine

The apparently near-term effects of the monoclonal antibody BAN2401 in slowing the progression of prodromal Alzheimer's disease (AD) has created cautious optimism about the therapeutic use of antibodies that neutralize cytotoxic soluble amyloid-β aggregates, rather than removing plaque. Plaque being protective, as it immobilizes cytotoxic amyloid-β, rather than AD's causative agent. The presence of natural antibodies against cytotoxic amyloid-β implies the existence of a protective anti-AD immunity. Hence, for vaccines to induce a similar immunoresponse that prevents and/or delays the onset of AD, they must have adjuvants that stimulate a sole anti-inflammatory Th2 immunity, plus immunogens that induce a protective immunoresponse against diverse cytotoxic amyloid-β conformers. Indeed, amyloid-β pleomorphism may explain the lack of long-term protection by monoclonal antibodies that neutralize single conformers, like aducanumab. A situation that would allow new cytotoxic conformers to escape neutralization by previously effective monoclonal antibodies. Stimulation of a vaccine's effective immunoresponse would require the concurrent delivery of immunogen to dendritic cells and their priming, to induce a polarized Th2 immunity. An immunoresponse that would produce besides neutralizing antibodies against neurotoxic amyloid-β oligomers, anti-inflammatory cytokines; preventing inflammation that aggravates AD. Because of age-linked immune decline, vaccines would be significantly more effective in preventing, rather than treating AD. Considering the amyloid-β's role in tau's pathological hyperphosphorylation and their synergism in AD, the development of preventive vaccines against both amyloid-β and tau should be considered. Due to convenience and cost, vaccines may be the only option available to many countries to forestall the impending AD epidemic.

Membrane Active Peptides and Their Biophysical Characterization

In the last 20 years, an increasing number of studies have been reported on membrane active peptides. These peptides exert their biological activity by interacting with the cell membrane, either to disrupt it and lead to cell lysis or to translocate through it to deliver cargos into the cell and reach their target. Membrane active peptides are attractive alternatives to currently used pharmaceuticals and the number of antimicrobial peptides (AMPs) and peptides designed for drug and gene delivery in the drug pipeline is increasing. Here, we focus on two most prominent classes of membrane active peptides; AMPs and cell-penetrating peptides (CPPs). Antimicrobial peptides are a group of membrane active peptides that disrupt the membrane integrity or inhibit the cellular functions of bacteria, virus, and fungi. Cell penetrating peptides are another group of membrane active peptides that mainly function as cargo-carriers even though they may also show antimicrobial activity. Biophysical techniques shed light on peptide–membrane interactions at higher resolution due to the advances in optics, image processing, and computational resources. Structural investigation of membrane active peptides in the presence of the membrane provides important clues on the effect of the membrane environment on peptide conformations. Live imaging techniques allow examination of peptide action at a single cell or single molecule level. In addition to these experimental biophysical techniques, molecular dynamics simulations provide clues on the peptide–lipid interactions and dynamics of the cell entry process at atomic detail. In this review, we summarize the recent advances in experimental and computational investigation of membrane active peptides with particular emphasis on two amphipathic membrane active peptides, the AMP melittin and the CPP pVEC.

Recent advancements toward therapeutic vaccines against Alzheimer's disease

INTRODUCTION

Alzheimer's disease (AD) is a devastating neurodegenerative disease characterized by protein aggregates of amyloid β (Aβ) and tau. These proteins have normal physiological functions, but in AD, they undergo a conformational change and aggregate as toxic oligomeric and fibrillar species with a high β-sheet content.

AREAS COVERED

Active and passive immunotherapeutic approaches are among the most attractive methods for targeting misfolded Aβ and tau. Promising preclinical testing of various immunotherapeutic approaches has yet to translate to cognitive benefits in human clinical trials. Knowledge gained from these past failures has led to the development of second-generation Aβ-active immunotherapies, anti-Aβ monoclonal antibodies targeting a wide array of Aβ conformations, and to a number of immunotherapies targeting pathological tau. This review covers the more recent advances in vaccine development for AD from 2016 to present.

EXPERT COMMENTARY

Due to the complex pathophysiology of AD, greatest clinical efficacy will most likely be achieved by concurrently targeting the most toxic forms of both Aβ and tau.

Early Aβ-HBc virus-like particles immunization had better effects on preventing the deficit of learning and memory abilities and reducing cerebral Aβ load in PDAPP mice

For nearly two decades, immunization against the β-amyloid peptide (Aβ) has been investigated as a potential treatment for Alzheimer's disease (AD). Despite some disappointing results in clinic trials, greater significance has been attached by some researchers to exploring the immune effects on pathological and cognitive changes in AD or producing new vaccines of AD. In the previous study, we have made a virus-like particles (Aβ-HBc VLPs) as Aβ vaccine candidate. Aβ-HBc VLPs could ameliorate the learning and memory abilities and reduce cerebral Aβ deposit in the old PDAPP mice. In the present study, to observe the preventive effect and the proper time of immunization, 3, 6 and 9-month old PDAPP mice were immunized with Aβ-HBc VLPs for 3 months. All mice generated high titer of anti-Aβ antibody after Aβ-HBc VLPs immunizations. When the mice were 15-month old, Morris Water Maze was used to test their learning and memory abilities. The escape latencies of Aβ-HBc VLPs immunized mice were shorter than that of control mice. These immunized mice entered platform region frequently and spent more time on the platform region and quadrant. 3 m and 6 m Aβ-HBc VLPs immunized groups performed better than the 9 m group. In immunohistochemistry tests, all the Aβ-HBc VLPs immunized mice had less amyloid deposit in cortex and hippocampus. ELISA results showed that soluble Aβ was reduced in the brain homogenates of the Aβ-HBc VLPs immunized mice, and 3- and 6-month groups had less soluble Aβ than the 9-month group. In conclusion, our study showed that Aβ-HBc VLPs immunization could elicit a strong immune response in adult APP mice, and early immunization had better effects on preventing learning and memory deficits, lowering Aβ burden in PDAPP mice.

The Relation Between Brain Amyloid Deposition, Cortical Atrophy, and Plasma Biomarkers in Amnesic Mild Cognitive Impairment and Alzheimer's Disease

Background: Neuritic plaques and neurofibrillary tangles are the pathological hallmarks of Alzheimer’s disease (AD), while the role of brain amyloid deposition in the clinical manifestation or brain atrophy remains unresolved. We aimed to explore the relation between brain amyloid deposition, cortical thickness, and plasma biomarkers.

Methods: We used ¹¹C-Pittsburgh compound B-positron emission tomography to assay brain amyloid deposition, magnetic resonance imaging to estimate cortical thickness, and an immunomagnetic reduction assay to measure plasma biomarkers. We recruited 39 controls, 25 subjects with amnesic mild cognitive impairment (aMCI), and 16 subjects with AD. PiB positivity (PiB+) was defined by the upper limit of the 95% confidence interval of the mean cortical SUVR from six predefined regions (1.0511 in this study).

Results: All plasma biomarkers showed significant between-group differences. The plasma Aβ₄₀ level was positively correlated with the mean cortical thickness of both the PiB+ and PiB- subjects. The plasma Aβ₄₀ level of the subjects who were PiB+ was negatively correlated with brain amyloid deposition. In addition, the plasma tau level was negatively correlated with cortical thickness in both the PiB+ and PiB- subjects. Moreover, cortical thickness was negatively correlated with brain amyloid deposition in the PiB+ subjects. In addition, the cut-off point of plasma tau for differentiating between controls and AD was higher in the PiB- group than in the PiB+ group (37.5 versus 25.6 pg/ml, respectively). Lastly, ApoE4 increased the PiB+ rate in the aMCI and control groups.

Conclusion: The contributions of brain amyloid deposition to cortical atrophy are spatially distinct. Plasma Aβ₄₀ might be a protective indicator of less brain amyloid deposition and cortical atrophy. It takes more tau pathology to reach the same level of cognitive decline in subjects without brain amyloid deposition, and ApoE4 plays an early role in amyloid pathogenesis.

Peptide based therapeutics and their use for the treatment of neurodegenerative and other diseases

Bioactive peptides are actively involved in different biological functions and importantly contribute to human health, and the use of peptides as therapeutics has a long successful history in disease management. A number of peptides have wide-ranging therapeutic effects, such as antioxidant, antimicrobial, and antithrombotic effects. Neurodegenerative diseases are typically caused by abnormal aggregations of proteins or peptides, and the depositions of these aggregates in or on neurons, disrupt signaling and eventually kill neurons. During recent years, research on short peptides has advanced tremendously. This review offers a brief introduction to peptide based therapeutics and their application in disease management and provides an overview of peptide vaccines, and toxicity related issues. In addition, the importance of peptides in the management of different neurodegenerative diseases and their therapeutic applications is discussed. The present review provides an understanding of peptides and their applications for the management of different diseases, but with focus on neurodegenerative diseases. The role of peptides as anti-cancer, antimicrobial and antidiabetic agents has also been discussed.