Immunization with amyloid-beta attenuates Alzheimer-disease-like pathology in the PDAPP mouse

Harnessing the immune system: vaccines to fight neurodegenerative diseases

Neurodegenerative diseases strongly impact our aging society, with treatments providing only symptomatic relief. Recent advancements in active immunotherapy offer solutions by stimulating the immune system to produce antibodies against misfolded and toxic amyloid proteins. We discuss vaccines under clinical evaluation for Alzheimer's and Parkinson's diseases, highlighting successes and ongoing trials.

Development of disease-modifying therapies against Alzheimer's disease

To successfully develop disease-modifying therapies (DMT) against Alzheimer's disease (AD), it is important to target the mild stage of the disease, before the pathological changes progress and dementia symptoms are fully manifested. To this end, the AD Neuroimaging Initiative (ADNI), a large-scale observational study, was initiated in the U.S. with the goal of development of DMT that are effective in the early stages of mild cognitive impairment (MCI) by utilizing imaging and biomarkers. In Japan, J-ADNI enrolled and followed up 537 patients, mainly with MCI, and established a platform for evaluation including amyloid PET, and demonstrated a high similarity in the clinical course of amyloid-positive MCI (prodromal AD) in Japan and the U.S. In 2023, the anti-Aβ antibody lecanemab successfully completed a Phase III clinical trial for early AD (prodromal AD + mild AD dementia) and was granted regulatory approval and made available both in the US and Japan. Also, phase III trial of donanemab was completed successful. The J-TRC study was initiated in Japan as a "trial ready cohort (TRC)" consisting of participants who met the eligibility criteria for participation in preclinical and prodromal AD trials. Based on such a platform, the development of DMT for AD will progress more rapidly in the future.

The immunology of B-1 cells: from development to aging

B-1 cells have intricate biology, with distinct function, phenotype and developmental origin from conventional B cells. They generate a B cell receptor with conserved germline characteristics and biased V(D)J recombination, allowing this innate-like lymphocyte to spontaneously produce self-reactive natural antibodies (NAbs) and become activated by immune stimuli in a T cell-independent manner. NAbs were suggested as "rheostats" for the chronic diseases in advanced age. In fact, age-dependent loss of function of NAbs has been associated with clinically-relevant diseases in the elderly, such as atherosclerosis and neurodegenerative disorders. Here, we analyzed comprehensively the ontogeny, phenotypic characteristics, functional properties and emerging roles of B-1 cells and NAbs in health and disease. Additionally, after navigating through the complexities of B-1 cell biology from development to aging, therapeutic opportunities in the field are discussed.

How will the emergence of lecanemab change dementia treatment?

The introduction of lecanemab has dramatically changed the field of dementia medicine. Lecanemab, defined as an anti-amyloid-β (Aβ) drug, comprises an antibody against Aβ, a protein structure believed to cause Alzheimer's disease. This drug represents a new direction in dementia treatment. In a phase III study, lecanemab was found to significantly slow cognitive decline, while showing manageable levels of amyloid-related imaging abnormalities, which are side-effects of lecanemab. Furthermore, lecanemab has been shown to effectively reduce Aβ accumulation in patients with early Alzheimer's disease, which might contribute not only to delaying the progression of cognitive decline, but also to improving the quality of life of patients and their families. However, there are conditions for the use of lecanemab, for which the Ministry of Health, Labor and Welfare has issued the Guidelines for Promotion of Optimal Use. These guidelines specify requirements for appropriate patient selection, prescribing physicians and administering medical institutions to ensure safe and effective use. Particular emphasis is placed on the confirmation of amyloid-β accumulation, amyloid-related imaging abnormalities risk management and appropriate handling of side-effects. The clinical use of lecanemab represents an important advancement in the treatment of dementia; however, the understanding and cooperation of healthcare professionals, patients and families are essential to maximize its efficacy and safety. Future issues to be addressed include the sustainability and long-term efficacy of treatment, improvement of clinical symptoms after removal of Aβ and motivation to administer the drug. Although lecanemab offers hope for the treatment of dementia, its use requires careful management. Geriatr Gerontol Int 2024; ••: ••-••.

A Perspective on Interdicting in Protein Misfolding for Therapeutic Drug Design: Modulating the Formation of Nonlocal Contacts in α-Synuclein as a Strategy against Parkinson's Disease

In recent work we proposed that interdiction in the earliest contact-formation events along the folding pathway of key viral proteins could provide a novel avenue for therapeutic drug design. In this Perspective we explore the potential applicability of the protein folding interdiction strategy in the realm of neurodegenerative diseases with a specific focus on synucleinopathies. In order to fulfill this goal we review the interdiction proposal and its practical challenges, and we present new results concerning design strategies for possible peptide drugs that could be useful in preventing α-synuclein aggregation.

Rodent Models of Alzheimer's Disease: Past Misconceptions and Future Prospects

Alzheimer's disease (AD) is a progressive neurodegenerative disease with no effective treatments, not least due to the lack of authentic animal models. Typically, rodent models recapitulate the effects but not causes of AD, such as cholinergic neuron loss: lesioning of cholinergic neurons mimics the cognitive decline reminiscent of AD but not its neuropathology. Alternative models rely on the overexpression of genes associated with familial AD, such as amyloid precursor protein, or have genetically amplified expression of mutant tau. Yet transgenic rodent models poorly replicate the neuropathogenesis and protein overexpression patterns of sporadic AD. Seeding rodents with amyloid or tau facilitates the formation of these pathologies but cannot account for their initial accumulation. Intracerebral infusion of proinflammatory agents offer an alternative model, but these fail to replicate the cause of AD. A novel model is therefore needed, perhaps similar to those used for Parkinson's disease, namely adult wildtype rodents with neuron-specific (dopaminergic) lesions within the same vulnerable brainstem nuclei, 'the isodendritic core', which are the first to degenerate in AD. Site-selective targeting of these nuclei in adult rodents may recapitulate the initial neurodegenerative processes in AD to faithfully mimic its pathogenesis and progression, ultimately leading to presymptomatic biomarkers and preventative therapies.

Novel Therapeutic Strategies in Alzheimer's Disease: Pitfalls and Challenges of Anti-Amyloid Therapies and Beyond

Alzheimer's disease (AD) causes a significant challenge to global healthcare systems, with limited effective treatments available. This review examines the landscape of novel therapeutic strategies for AD, focusing on the shortcomings of traditional therapies against amyloid-beta (Aβ) and exploring emerging alternatives. Despite decades of research emphasizing the role of Aβ accumulation in AD pathogenesis, clinical trials targeting Aβ have obtained disappointing results, highlighting the complexity of AD pathophysiology and the need for investigating other therapeutic approaches. In this manuscript, we first discuss the challenges associated with anti-Aβ therapies, including limited efficacy and potential adverse effects, underscoring the necessity of exploring alternative mechanisms and targets. Thereafter, we review promising non-Aβ-based strategies, such as tau-targeted therapies, neuroinflammation modulation, and gene and stem cell therapy. These approaches offer new avenues for AD treatment by addressing additional pathological hallmarks and downstream effects beyond Aβ deposition.

Immunotherapy: An emerging treatment option for neurodegenerative diseases

Accumulation of misfolded proteins and protein aggregates leading to degeneration of neurons is a hallmark of several neurodegenerative diseases. Therapy mostly relies on symptomatic relief. Immunotherapy offers a promising approach for the development of disease-modifying routes. Such strategies have shown remarkable results in oncology, and this promise is increasingly being realized for neurodegenerative diseases in advanced preclinical and clinical studies. This review highlights cases of passive and active immunotherapies in Parkinson's and Alzheimer's diseases. The reasons for success and failure, wherever available, and strategies to cross the blood-brain barrier, are discussed. The need for conditional modulation of the immune response is also reflected on.

Sensor-integrated brain-on-a-chip platforms: Improving the predictive validity in neurodegenerative research

Affecting millions of individuals worldwide, neurodegenerative diseases (NDDs) pose a significant and growing health concern in people over the age of 60 years. Contributing to this trend are the steady increase in the aging population coupled with a persistent lack of disease-altering treatment strategies targeting NDDs. The absence of efficient therapeutics can be attributed to high failure rates in clinical trials and the ineptness of animal models in preceding preclinical studies. To that end, in recent years, significant research effort has been dedicated to the development of human cell-based preclinical disease models characterized by a higher degree of predictive validity. However, a key requirement of any in vitro model constitutes the precise knowledge and replication of the target tissues' (patho-)physiological microenvironment. Herein, microphysiological systems have demonstrated superiority over conventional static 2D/3D in vitro cell culture systems, as they allow for the emulation and continuous monitoring of the onset, progression, and remission of disease-associated phenotypes. This review provides an overview of recent advances in the field of NDD research using organ-on-a-chip platforms. Specific focus is directed toward non-invasive sensing strategies encompassing electrical, electrochemical, and optical sensors. Additionally, promising on- and integrable off-chip sensing strategies targeting key analytes in NDDs will be presented and discussed in detail.

Will cellular immunotherapies end neurodegenerative diseases?

Neurodegenerative disorders present major challenges to global health, exacerbated by an aging population and the absence of therapies. Despite diverse pathological manifestations, they share a common hallmark, loosely termed 'neuroinflammation'. The prevailing dogma is that the immune system is an active contributor to neurodegeneration; however, recent evidence challenges this. By analogy with road construction, which causes temporary closures and disruptions, the immune system's actions in the central nervous system (CNS) might initially appear destructive, and might even cause harm, while aiming to combat neurodegeneration. We propose that the application of cellular immunotherapies to coordinate the immune response towards remodeling might pave the way for new modes of tackling the roadblocks of neurodegenerative diseases.

Review of valiltramiprosate (ALZ-801) for the treatment of Alzheimer's disease: a novel small molecule with disease modifying potential

INTRODUCTION

Alzheimer's disease (AD) is a neurodegenerative condition characterized by progressive cognitive deterioration, functional impairments, and neuropsychiatric symptoms. Valiltramiprosate is a tramiprosate prodrug being investigated as a novel treatment for AD.

AREAS COVERED

The online databases PubMed, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov were searched using the terms 'ALZ-801' or 'valiltramiprosate.' Alzheon press releases were reviewed for emerging clinical information. Valiltramiprosate is an oral, well-tolerated synthetic valine-conjugate prodrug of tramiprosate. Valiltramiprosate's active metabolite include tramiprosate and 3-sulfopropanoic acid. Proposed mechanism of action is multiligand binding to Aβ42 which stabilizes amyloid monomers to prevent peptide aggregation and oligomerization. Pharmacokinetic studies show 52% oral bioavailability, rapid absorption, approximately 40% brain-drug exposure, and near complete renal clearance. Compared to tramiprosate, valiltramiprosate extends plasma tramiprosate half-life and improves interindividual pharmacokinetic variability. Interim analyses from valiltramiprosate's phase II biomarker trial show: (1) significant reductions in plasma p-tau181 and related AD fluid biomarkers; (2) brain structure preservation and reduced hippocampal atrophy by MRI; and (3) improvements on cognitive assessments at multiple timepoints. Its phase III clinical trial in ApoE ε4 homozygotes is near completion.

EXPERT OPINION

Valiltramiprosate's clinical trial data show early indications of efficacy with potential disease modifying effect in AD.

Structural insights into the potential binding sites of Cathepsin D using molecular modelling techniques

Alzheimer's disease (AD) is the most prevalent type of dementia caused by the accumulation of amyloid beta (Aβ) peptides. The extracellular deposition of Aβ peptides in human AD brain causes neuronal death. Therefore, it has been found that Aβ peptide degradation is a possible therapeutic target for AD. CathD has been known to breakdown amyloid beta peptides. However, the structural role of CathD is not yet clear. Hence, for the purpose of gaining a deeper comprehension of the structure of CathD, the present computational investigation was performed using virtual screening technique to predict CathD's active site residues and substrate binding mode. Ligand-based virtual screening was implemented on small molecules from ZINC database against crystal structure of CathD. Further, molecular docking was utilised to investigate the binding mechanism of CathD with substrates and virtually screened inhibitors. Localised compounds obtained through screening performed by PyRx and AutoDock 4.2 with CathD receptor and the compounds having highest binding affinities were picked as; ZINC00601317, ZINC04214975 and ZINCC12500925 as our top choices. The hydrophobic residues Viz. Gly35, Val31, Thr34, Gly128, Ile124 and Ala13 help stabilising the CathD-ligand complexes, which in turn emphasises substrate and inhibitor selectivity. Further, MM-GBSA approach has been used to calculate binding free energy between CathD and selected compounds. Therefore, it would be beneficial to understand the active site pocket of CathD with the assistance of these discoveries. Thus, the present study would be helpful to identify active site pocket of CathD, which could be beneficial to develop novel therapeutic strategies for the AD.

Therapeutic approaches in proteinopathies

A family of maladies known as amyloid disorders, proteinopathy, or amyloidosis, are characterized by the accumulation of abnormal protein aggregates containing cross-β-sheet amyloid fibrils in many organs and tissues. Often, proteins that have been improperly formed or folded make up these fibrils. Nowadays, most treatments for amyloid illness focus on managing symptoms rather than curing or preventing the underlying disease process. However, recent advances in our understanding of the biology of amyloid diseases have led to the development of innovative therapies that target the emergence and accumulation of amyloid fibrils. Examples of these treatments include the use of small compounds, monoclonal antibodies, gene therapy, and others. In the end, even if the majority of therapies for amyloid diseases are symptomatic, greater research into the biology behind these disorders is identifying new targets for potential therapy and paving the way for the development of more effective treatments in the future.

The advent of Alzheimer treatments will change the trajectory of human aging

Slowing neurodegenerative disorders of late life has lagged behind progress on other chronic diseases. But advances in two areas, biochemical pathology and human genetics, have now identified early pathogenic events, enabling molecular hypotheses and disease-modifying treatments. A salient example is the discovery that antibodies to amyloid ß-protein, long debated as a causative factor in Alzheimer's disease (AD), clear amyloid plaques, decrease levels of abnormal tau proteins and slow cognitive decline. Approval of amyloid antibodies as the first disease-modifying treatments means a gradually rising fraction of the world's estimated 60 million people with symptomatic disease may decline less or even stabilize. Society is entering an era in which the unchecked devastation of AD is no longer inevitable. This Perspective considers the impact of slowing AD and other neurodegenerative disorders on the trajectory of aging, allowing people to survive into late life with less functional decline. The implications of this moment for medicine and society are profound.

Up-regulation of GPR139 in the medial septum ameliorates cognitive impairment in two mouse models of Alzheimer's disease

G-protein coupled receptors (GPCRs) constitute the largest class of cell surface receptors and present prominent drug targets. GPR139 is an orphan GPCR detected in the septum of the brain. However, its roles in cognition are still unclear. Here we first established a mouse model of cognitive impairment by a single intracerebroventricular injection of aggregated amyloid-beta peptide 1-42 (Aβ1-42). RNA-sequencing data analysis showed that Aβ1-42 induced a significant decrease of GPR139 mRNA in the basal forebrain. Using GPR139 agonist JNJ-63533054 and behavioral tests, we found that GPR139 activation in the brain ameliorated Aβ1-42-induced cognitive impairment. Using western blot, TUNEL apoptosis and Golgi staining assays, we showed that GPR139 activation alleviated Aβ1-42-induced apoptosis and synaptotoxicity in the basal forebrain rather than prefrontal cortex and hippocampus. The further study identified that GPR139 was widely expressed in cholinergic neurons of the medial septum (MS). Using the overexpression virus and transgenic animal model, we showed that up-regulation of GPR139 in MS cholinergic neurons ameliorated cognitive impairment, apoptosis and synaptotoxicity in APP/PS1 transgenic mice. These findings reveal that GPR139 of MS cholinergic neurons could be a critical node in cognition and potentially provides insight into the pathogenesis of Alzheimer's disease.

Creutzfeldt-Jakob disease and other prion diseases

Prion diseases share common clinical and pathological characteristics such as spongiform neuronal degeneration and deposition of an abnormal form of a host-derived protein, termed prion protein. The characteristic features of prion diseases are long incubation times, short clinical courses, extreme resistance of the transmissible agent to degradation and lack of nucleic acid involvement. Sporadic and genetic forms of prion diseases occur worldwide, of which genetic forms are associated with mutations in PRNP. Human to human transmission of these diseases has occurred due to iatrogenic exposure, and zoonotic forms of prion diseases are linked to bovine disease. Significant progress has been made in the diagnosis of these disorders. Clinical tools for diagnosis comprise brain imaging and cerebrospinal fluid tests. Aggregation assays for detection of the abnormally folded prion protein have a clear potential to diagnose the disease in peripherally accessible biofluids. After decades of therapeutic nihilism, new treatment strategies and clinical trials are on the horizon. Although prion diseases are relatively rare disorders, understanding their pathogenesis and mechanisms of prion protein misfolding has significantly enhanced the field in research of neurodegenerative diseases.

Tau Immunotherapies for Alzheimer's Disease and Related Tauopathies: Status of Trials and Insights from Preclinical Studies

 The tau protein undergoes pathological changes in Alzheimer's disease and other tauopathies that eventually lead to functional impairments. Over the years, several therapeutic approaches have been examined to slow or halt the progression of tau pathology but have yet to lead to an approved disease-modifying treatment. Of the drugs in clinical trials that directly target tau, immunotherapies are the largest category and mostly consist of antibodies in different stages of development. There is a reasonable optimism that at least some of these compounds will have a clinically meaningful efficacy. This view is based on the significant although modest efficacy of some antibodies targeting amyloid-β in Alzheimer's disease and the fact that tau pathology correlates much better with the degree of dementia than amyloid-β lesions. In Alzheimer's disease, clearing pathological tau may therefore improve function later in the disease process than when removing amyloid-β. This review provides a brief update on the active and passive clinical tau immunization trials with insight from preclinical studies. Various epitopes are being targeted and some of the antibodies are said to target extracellular tau but because almost all of pathological tau is found intracellularly, the most efficacious antibodies should be able to enter the cell.

Passive immunotherapy for Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disease characterized by cognitive impairment with few therapeutic options. Despite many failures in developing AD treatment during the past 20 years, significant advances have been achieved in passive immunotherapy of AD very recently. Here, we review characteristics, clinical trial data, and mechanisms of action for monoclonal antibodies (mAbs) targeting key players in AD pathogenesis, including amyloid-β (Aβ), tau and neuroinflammation modulators. We emphasized the efficacy of lecanemab and donanemab on cognition and amyloid clearance in AD patients in phase III clinical trials and discussed factors that may contribute to the efficacy and side effects of anti-Aβ mAbs. In addition, we provided important information on mAbs targeting tau or inflammatory regulators in clinical trials, and indicated that mAbs against the mid-region of tau or pathogenic tau have therapeutic potential for AD. In conclusion, passive immunotherapy targeting key players in AD pathogenesis offers a promising strategy for effective AD treatment.

Transgenic amyloid precursor protein mouse models of amyloidosis. Incomplete models for Alzheimer's disease but effective predictors of anti-amyloid therapies

INTRODUCTION

Amyloid precursor protein (APP) transgenic mice are models of Alzheimer's disease (AD) amyloidosis, not all of AD. Diffuse, compacted, and vascular deposits in APP mice mimic those found in AD cases.

METHODS

Most interventional studies in APP mice start treatment early in the process of amyloid deposition, consistent with a prevention treatment regimen. Most clinical trials treat patients with established amyloid deposits in a therapeutic treatment regimen.

RESULTS

The first treatment to reduce amyloid and cognitive impairment in mice was immunotherapy. The APP mouse models not only predicted efficacy, but presaged the vascular leakage called ARIA. The recent immunotherapy clinical trials that removed amyloid and slowed cognitive decline confirms the utility of these early APP models when used in therapeutic designs.

DISCUSSION

New mouse models of AD pathologies will add to the research armamentarium, but the early models have accurately predicted responses to amyloid therapies in humans.

The amyloid-β peptide: Guilty as charged?

Recent years have seen both considerable progress and controversy in the Alzheimer's disease (AD) field. After decades of slow to negligible movement towards the development of disease modifying therapies, promising outcomes in recent clinical trials with several monoclonal antibodies targeting various forms of the amyloid-β (Aβ) peptide have at last opened a possible way forward. In fact, at this point multiple anti-Aβ therapeutics are close to receiving (or have already received) regulatory approval. Although these outcomes are not without some degree of divisiveness, the fact remains that targeting amyloid for removal has finally shown at least modest efficacy in slowing the otherwise relentless progression of the disease. Although the validation of the long standing amyloid cascade hypothesis would seem to be at hand, what remains is the puzzling issue of why - if Aβ indeed causes AD - does removing it from the brain not stop the disease entirely.

Lessons Learned from Approval of Aducanumab for Alzheimer's Disease

When the US Food and Drug Administration used the accelerated approval process to authorize the use of the antiamyloid drug aducanumab to treat Alzheimer's disease (AD), many people hoped this signaled a new era of disease-modifying treatment. But 2 years later, aducanumab's failure to launch provides a cautionary tale about the complexities of dementia and the need for a thorough and transparent review of the role that regulatory agencies and various stakeholders play in approving AD drugs. We highlight the events leading to aducanumab's controversial approval and discuss some of the key lessons learned from the drug's failure to deliver the hoped-for benefits. These lessons include the inherent limitations of antiamyloid strategies for a complex disease in which amyloid is only one of several pathological processes, the need for clinical trials that better reflect the diversity of communities affected by AD, the potential pitfalls of futility analyses in clinical trials, the need for greater transparency and other modifications to the approval process, and the dementia field's unreadiness to move from the highly controlled environment of clinical trials to the widespread and chronic use of resource-intensive, disease-modifying drugs in real-world treatment scenarios. People with dementia desperately need effective therapies. We hope that the aducanumab story will inspire changes to the approval process-changes that restore public trust and improve future efforts to deliver disease-modifying therapies to the clinic.

A chromogenic diarylethene-based probe for the detection of Cu2+ in aqueous medium in Drosophila for early diagnosis of Alzheimer

A diarylethene-based probe (Z)-N'-((2-amino-5-chlorophenyl)(phenyl)methylene)-2-hydroxy benzohydrazide (KBH) has been proficiently developed and its structure has been confirmed by single crystal X-ray diffraction technique. It displays a selective and sensitive colorimetric sensing of Cu2+ ions in aqueous medium with a naked eye colour change from colourless to yellow. It exhibits a significantly low limit of detection as 1.5 nM. A plausible binding mechanism has been proposed using Job's plot, FT-IR, 1H NMR titration, HRMS and DFT studies. The chemosensor is effectively reversible and reusable with EDTA. Test strip kit and real water sample analysis have been shown to establish its practical applicability. Further, the potential of KBH for the early diagnosis of Cu2+ ion-induced amyloid toxicity has been investigated in eye imaginal disc of Alzheimer's disease model of Drosophila 3rd instar larvae. The in-vivo interaction of KBH with Cu2+ in gut tissues of Drosophila larvae establishes its sensing capability in biological system. Interestingly, the in-vivo detection of Cu2+ has been done using bright field imaging which eliminates the necessity of a fluorescent label, hence making the method highly economical.

Therapeutic Effects of Aβ-Specific Regulatory T Cells in Alzheimer's Disease: A Study in 5xFAD Mice

The aging global population is placing an increasing burden on healthcare systems, and the social impact of Alzheimer's disease (AD) is on the rise. However, the availability of safe and effective treatments for AD remains limited. Adoptive Treg therapy has been explored for treating neurodegenerative diseases, including AD. To facilitate the clinical application of Treg therapy, we developed a Treg preparation protocol and highlighted the therapeutic effects of Tregs in 5xFAD mice. CD4+CD25+ Tregs, isolated after Aβ stimulation and expanded using a G-rex plate with a gas-permeable membrane, were adoptively transferred into 5xFAD mice. Behavioral analysis was conducted using Y-maze and passive avoidance tests. Additionally, we measured levels of Aβ, phosphorylated tau (pTAU), and nitric oxide synthase 2 (NOS2) in the hippocampus. Real-time RT-PCR was employed to assess the mRNA levels of pro- and anti-inflammatory markers. Our findings indicate that Aβ-specific Tregs not only improved cognitive function but also reduced Aβ and pTAU accumulation in the hippocampus of 5xFAD mice. They also inhibited microglial neuroinflammation. These effects were observed at doses as low as 1.5 × 103 cells/head. Collectively, our results demonstrate that Aβ-specific Tregs can mitigate AD pathology in 5xFAD mice.

Anti-Amyloid Monoclonal Antibodies for the Treatment of Alzheimer's Disease

Two monoclonal antibodies (mAbs), aducanumab and lecanemab, have received accelerated approval from the US FDA for initiation of treatment in early Alzheimer's disease patients who have proven β-amyloid pathology (Aβ). One of these, lecanemab, has subsequently received full approval and other monoclonal antibodies are poised for positive review and approval. Anti-amyloid mAbs share the feature of producing a marked reduction in total brain Aβ revealed by amyloid positron emission tomography. Trials associated with slowing of cognitive decline have achieved a reduction in measurable plaque Aβ in the range of 15-25 centiloids; trials of agents that did not reach this threshold were not associated with cognitive benefit. mAbs have differences in terms of titration schedules, MRI monitoring schedules for amyloid-related imaging abnormalities (ARIA), and continuing versus interrupted therapy. The approximate 30% slowing of decline observed with mAbs is clinically meaningful in terms of extended cognitive integrity and delay of onset of the more severe dementia phases of Alzheimer's disease. Approval of these agents initiates a new era in Alzheimer's disease therapeutics with disease-modifying properties. Further advances are needed, i.e. greater efficacy, improved safety, enhanced convenience, and better understanding of ill-understood observations such as brain volume loss.

Mechanisms and structure-activity relationships of polysaccharides in the intervention of Alzheimer's disease: A review

Alzheimer's disease (AD) is a complex neurodegenerative disease. Despite several decades of research, the development of effective treatments and responses for Alzheimer's disease remains elusive. The utilization of polysaccharides for Alzheimer's disease became more popular due to their beneficial characteristics, notably their multi-target activity and low toxicity. This review mainly focuses on the researches of recent 5 years in the regulation of AD by naturally derived polysaccharides, systematically lists the possible intervention pathways of polysaccharides from different mechanisms, and explores the structure-activity relationship between polysaccharide structural activities, so as to provide references for the intervention and treatment of AD by polysaccharides.

Improving Cognition Without Clearing Amyloid: Effects of Tau and Ultrasound Neuromodulation

Alzheimer's disease is characterized by progressive impairment of neuronal functions culminating in neuronal loss and dementia. A universal feature of dementia is protein aggregation, a process by which a monomer forms intermediate oligomeric assembly states and filaments that develop into end-stage hallmark lesions. In Alzheimer's disease, this is exemplified by extracellular amyloid-β (Aβ) plaques which have been placed upstream of tau, found in intracellular neurofibrillary tangles and dystrophic neurites. This implies causality that can be modeled as a linear activation cascade. When Aβ load is reduced, for example, in response to an anti-Aβ immunotherapy, cognitive functions improve in plaque-forming mice. They also deteriorate less in clinical trial cohorts although real-world clinical benefits remain to be demonstrated. Given the existence of aged humans with unimpaired cognition despite a high plaque load, the central role of Aβ has been challenged. A counter argument has been that clinical symptoms would eventually develop if these aged individuals were to live long enough. Alternatively, intrinsic mechanisms that protect the brain in the presence of pathology may exist. In fact, Aβ toxicity can be abolished by either reducing or manipulating tau (through which Aβ signals), at least in preclinical models. In addition to manipulating steps in this linear pathocascade model, mechanisms of restoring brain reserve can also counteract Aβ toxicity. Low-intensity ultrasound is a neuromodulatory modality that can improve cognitive functions in Aβ-depositing mice without the need for removing Aβ. Together, this highlights a dissociation of Aβ and cognition, with important implications for therapeutic interventions.

Alzheimer's Disease Immunotherapy: Current Strategies and Future Prospects

Alzheimer's disease (AD) is an extremely complex and heterogeneous pathology influenced by many factors contributing to its onset and progression, including aging, amyloid-beta (Aβ) plaques, tau fibril accumulation, inflammation, etc. Despite promising advances in drug development, there is no cure for AD. Although there have been substantial advancements in understanding the pathogenesis of AD, there have been over 200 unsuccessful clinical trials in the past decade. In recent years, immunotherapies have been at the forefront of these efforts. Immunotherapy alludes to the immunological field that strives to identify disease treatments via the enhancement, suppression, or induction of immune responses. Interestingly, immunotherapy in AD is a relatively new approach for non-infectious disease. At present, antibody therapy (passive immunotherapy) that targets anti-Aβ aimed to prevent the fibrillization of Aβ peptides and disrupt pre-existing fibrils is a predominant AD immunotherapy due to the continuous failure of active immunotherapy for AD. The most rational and safe strategies will be those targeting the toxic molecule without triggering an abnormal immune response, offering therapeutic advantages, thus making clinical trial design more efficient. This review offers a concise overview of immunotherapeutic strategies, including active and passive immunotherapy for AD. Our review encompasses approved methods and those presently under investigation in clinical trials, while elucidating the recent challenges, complications, successes, and potential treatments. Thus, immunotherapies targeting Aβ throughout the disease progression using a mutant oligomer-Aβ stimulated dendritic cell vaccine may offer a promising therapy in AD.

Re-Arranging the Puzzle between the Amyloid-Beta and Tau Pathology: An APP-Centric Approach

After several years of research in the field of Alzheimer's disease (AD), it is still unclear how amyloid-beta (Aβ) and Tau, two key hallmarks of the disease, mediate the neuropathogenic events that lead to AD. Current data challenge the "Amyloid Cascade Hypothesis" that has prevailed in the field of AD, stating that Aβ precedes and triggers Tau pathology that will eventually become the toxic entity in the progression of the disease. This perspective also led the field of therapeutic approaches towards the development of strategies that target Aβ or Tau. In the present review, we discuss recent literature regarding the neurotoxic role of both Aβ and Tau in AD, as well as their physiological function in the healthy brain. Consequently, we present studies suggesting that Aβ and Tau act independently of each other in mediating neurotoxicity in AD, thereafter, re-evaluating the "Amyloid Cascade Hypothesis" that places Tau pathology downstream of Aβ. More recent studies have confirmed that both Aβ and Tau could propagate the disease and induce synaptic and memory impairments via the amyloid precursor protein (APP). This finding is not only interesting from a mechanistic point of view since it provides better insights into the AD pathogenesis but also from a therapeutic point of view since it renders APP a common downstream effector for both Aβ and Tau. Subsequently, therapeutic strategies that act on APP might provide a more viable and physiologically relevant approach for targeting AD.

Current Anti-Amyloid-β Therapy for Alzheimer's Disease Treatment: From Clinical Research to Nanomedicine

Recent successive approval of anti-amyloid-β (Aβ) monoclonal antibodies as disease-modifying therapies against Alzheimer's disease (AD) has raised great confidence in the development of anti-AD therapies; however, the current therapies still face the dilemma of significant adverse reactions and limited effects. In this review, we summarized the therapeutic characteristics of the approved anti-Aβ immunotherapies and dialectically analyzed the gains and losses from clinical trials. The review further proposed the reasonable selection of animal models in preclinical studies from the perspective of different animal models of Aβ deposition and deals in-depth with the recent advances of exploring preclinical nanomedical application in Aβ targeted therapy, aiming to provide a reliable systematic summary for the development of novel anti-Aβ therapies. Collectively, this review comprehensively dissects the pioneering work of Aβ-targeted therapies and proposed perspective insight into AD-modified therapies.

Amyloid-β specific regulatory T cells attenuate Alzheimer's disease pathobiology in APP/PS1 mice

BACKGROUND

Regulatory T cells (Tregs) maintain immune tolerance. While Treg-mediated neuroprotective activities are now well-accepted, the lack of defined antigen specificity limits their therapeutic potential. This is notable for neurodegenerative diseases where cell access to injured brain regions is required for disease-specific therapeutic targeting and improved outcomes. To address this need, amyloid-beta (Aβ) antigen specificity was conferred to Treg responses by engineering the T cell receptor (TCR) specific for Aβ (TCRAβ). The TCRAb were developed from disease-specific T cell effector (Teff) clones. The ability of Tregs expressing a transgenic TCRAβ (TCRAβ -Tregs) to reduce Aβ burden, transform effector to regulatory cells, and reverse disease-associated neurotoxicity proved beneficial in an animal model of Alzheimer's disease.

METHODS

TCRAβ -Tregs were generated by CRISPR-Cas9 knockout of endogenous TCR and consequent incorporation of the transgenic TCRAb identified from Aβ reactive Teff monoclones. Antigen specificity was confirmed by MHC-Aβ-tetramer staining. Adoptive transfer of TCRAβ-Tregs to mice expressing a chimeric mouse-human amyloid precursor protein and a mutant human presenilin-1 followed measured behavior, immune, and immunohistochemical outcomes.

RESULTS

TCRAβ-Tregs expressed an Aβ-specific TCR. Adoptive transfer of TCRAβ-Tregs led to sustained immune suppression, reduced microglial reaction, and amyloid loads. 18F-fluorodeoxyglucose radiolabeled TCRAβ-Treg homed to the brain facilitating antigen specificity. Reduction in amyloid load was associated with improved cognitive functions.

CONCLUSIONS

TCRAβ-Tregs reduced amyloid burden, restored brain homeostasis, and improved learning and memory, supporting the increased therapeutic benefit of antigen specific Treg immunotherapy for AD.

Biomarkers associated with the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is a progressive degenerative neurological illness with insidious onset. Due to the complexity of the pathogenesis of AD and different pathological changes, the clinical phenotypes of dementia are diverse, and these pathological changes also interact with each other. Therefore, it is of great significance to search for biomarkers that can diagnose these pathological changes to improve the ability to monitor the course of disease and treat the disease. The pathological mechanism hypothesis with high recognition of AD mainly includes the accumulation of β-amyloid (Aβ) around neurons and hyperphosphorylation of tau protein, which results in the development of neuronal fiber tangles (NFTs) and mitochondrial dysfunction. AD is an irreversible disease; currently, there is no clinical cure or delay in the disease process of drugs, and there is a lack of effective early clinical diagnosis methods. AD patients, often in the dementia stages and moderate cognitive impairment, will seek medical treatment. Biomarkers can help diagnose the presence or absence of specific diseases and their pathological processes, so early screening and diagnosis are crucial for the prevention and therapy of AD in clinical practice. β-amyloid deposition (A), tau pathology (T), and neurodegeneration/neuronal damage (N), also known as the AT (N) biomarkers system, are widely validated core humoral markers for the diagnosis of AD. In this paper, the pathogenesis of AD related to AT (N) and the current research status of cerebrospinal fluid (CSF) and blood related biomarkers were reviewed. At the same time, the limitations of humoral markers in the diagnosis of AD were also discussed, and the future development of humoral markers for AD was prospected. In addition, the contents related to mitochondrial dysfunction, prion virology and intestinal microbiome related to AD are also described, so as to understand the pathogenesis of AD in many aspects and dimensions, so as to evaluate the pathological changes related to AD more comprehensively and accurately.

Immunization Effects of a Novel α-Synuclein-Based Peptide Epitope Vaccine in Parkinson's Disease-Associated Pathology

Parkinson's disease (PD) is a chronic neurodegenerative disease that affects the central nervous system, specifically the motor system. It is mainly caused by the loss of dopamine due to the accumulation of α-synuclein (α-syn) protein in the striatum and substantia nigra pars compacta (SNpc). Previous studies have reported that immunization may be a potential preventive strategy for neurodegenerative diseases such as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS). Therefore, the aim of the study was to design an α-syn specific epitope vaccine and investigate its effect in PD-related pathophysiology using an α-syn-induced mouse model. We used an in silico model to identify and design a non-toxic α-syn-based peptide epitope vaccine and, to overcome poor immunogenicity, the vaccine was coupled with immunogenic carrier proteins, i.e., ovalbumin (OVA) and keyhole limpet haemocyanin (KLH). Our results showed that vaccinated PD mouse models, especially with vaccines with carrier proteins, improved in motor functions compared with the non-vaccinated PD model. Additionally, the vaccinated groups showed increased immunoglobulin G (IgG) levels in the spleen and plasma as well as decreased interleukin-10 (IL-10) levels in the plasma. Furthermore, vaccinated groups, especially OVA and KLH groups, showed decrease in α-syn levels and increased dopamine-related markers, i.e., tyrosine hydroxylase (TH), vesicle monoamine transporter 2 (VMAT2), and dopamine transporter (DAT), and autophagy activities in the striatum and SNpc. Lastly, our data showed decreased neuroinflammation by reducing the activation of microglia and astrocytes and pro-inflammatory cytokines in the immunized groups, especially with OVA and KLH carrier proteins. Overall, these results suggest that vaccination, especially with immunogenic carrier proteins, is effective in reducing the accumulation of α-syn aggregates in the brain and ameliorate PD-related pathophysiology. Hence, further development of this approach might have a potential role in preventing the development of PD.

Recent advancement in therapeutic strategies for Alzheimer's disease: Insights from clinical trials

Alzheimer's disease (AD) is the most prevalent form of dementia, characterized by the presence of plaques of amyloid beta and Tau proteins. There is currently no permanent cure for AD; the only medications approved by the FDA for mild to moderate AD are cholinesterase inhibitors, NMDA receptor antagonists, and immunotherapies against core pathophysiology, that provide temporary relief only. Researchers worldwide have made significant attempts to find new targets and develop innovative therapeutic molecules to treat AD. The FDA-approved drugs are palliative and couldn't restore the damaged neuron cells of AD. Stem cells have self-differentiation properties, making them prospective therapeutics to treat AD. The promising results in pre-clinical studies of stem cell therapy for AD seek attention worldwide. Various stem cells, mainly mesenchymal stem cells, are currently in different phases of clinical trials and need more advancements to take this therapy to the translational level. Here, we review research from the past decade that has identified several hypotheses related to AD pathology. Moreover, this article also focuses on the recent advancement in therapeutic strategies for AD treatment including immunotherapy and stem cell therapy detailing the clinical trials that are currently undergoing development.

Accelerating Alzheimer's therapeutic development: The past and future of clinical trials

Alzheimer's disease (AD) research has entered a new era with the recent positive phase 3 clinical trials of the anti-Aβ antibodies lecanemab and donanemab. Why did it take 30 years to achieve these successes? Developing potent therapies for reducing fibrillar amyloid was key, as was selection of patients at relatively early stages of disease. Biomarkers of the target pathologies, including amyloid and tau PET, and insights from past trials were also critical to the recent successes. Moving forward, the challenge will be to develop more efficacious therapies with greater efficiency. Novel trial designs, including combination therapies and umbrella and basket protocols, will accelerate clinical development. Better diversity and inclusivity of trial participants are needed, and blood-based biomarkers may help to improve access for medically underserved groups. Incentivizing innovation in both academia and industry through public-private partnerships, collaborative mechanisms, and the creation of new career paths will be critical to build momentum in these exciting times.

High-throughput autoantibody screening identifies differentially abundant autoantibodies in autism spectrum disorder

Introduction

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by defects in two core domains, social/communication skills and restricted/repetitive behaviors or interests. There is no approved biomarker for ASD diagnosis, and the current diagnostic method is based on clinical manifestation, which tends to vary vastly between the affected individuals due to the heterogeneous nature of ASD. There is emerging evidence that supports the implication of the immune system in ASD, specifically autoimmunity; however, the role of autoantibodies in ASD children is not yet fully understood.

Materials and methods

In this study, we screened serum samples from 93 cases with ASD and 28 healthy controls utilizing high-throughput KoRectly Expressed (KREX) i-Ome protein-array technology. Our goal was to identify autoantibodies with differential expressions in ASD and to gain insights into the biological significance of these autoantibodies in the context of ASD pathogenesis.

Result

Our autoantibody expression analysis identified 29 differential autoantibodies in ASD, 4 of which were upregulated and 25 downregulated. Subsequently, gene ontology (GO) and network analysis showed that the proteins of these autoantibodies are expressed in the brain and involved in axonal guidance, chromatin binding, and multiple metabolic pathways. Correlation analysis revealed that these autoantibodies negatively correlate with the age of ASD subjects.

Conclusion

This study explored autoantibody reactivity against self-antigens in ASD individuals' serum using a high-throughput assay. The identified autoantibodies were reactive against proteins involved in axonal guidance, synaptic function, amino acid metabolism, fatty acid metabolism, and chromatin binding.

Implications of the Approval of Lecanemab for Alzheimer Disease Patient Care: Incremental Step or Paradigm Shift?

The amyloid cascade model of the pathogenesis of Alzheimer disease (AD) is well supported in observational studies. Its therapeutic corollary asserts that removal of amyloid-β peptide ("amyloid") would provide clinical benefits. After 2 decades of pursuing the strategy of amyloid removal without success, clinical trials of the antiamyloid monoclonal antibody (AAMA) donanemab and a phase 3 clinical trial of lecanemab have reported clinical benefits linked to amyloid removal. Lecanemab (trade name, Leqembi) is the first with published phase 3 trial results. When administered through IV every 2 weeks to patients with elevated brain amyloid and mild cognitive impairment or mild dementia, lecanemab delayed cognitive and functional worsening by approximately 5 months in an 18-month double-blind, placebo-controlled trial. The trial was well conducted, and the results favoring lecanemab were internally consistent. The demonstration that lecanemab treatment delayed clinical progression in persons with mild symptoms due to AD is a major conceptual achievement, but a better appreciation of the magnitude and durability of benefits for individual patients will require extended observations from clinical practice settings. Amyloid-related imaging abnormalities (ARIA) that were largely asymptomatic occurred in approximately 20%, slightly more than half of which were attributable to treatment and the rest to underlying AD-related amyloid angiopathy. Persons who were homozygous for the APOE ε4 allele had greater ARIA risks. Hemorrhagic complications with longer-term lecanemab use need to be better understood. Administration of lecanemab will place unprecedented pressures on dementia care personnel and infrastructure, both of which need to grow exponentially to meet the challenge.

Alzheimer's disease: From immunotherapy to immunoprevention

Recent Aβ-immunotherapy trials have yielded the first clear evidence that removing aggregated Aβ from the brains of symptomatic patients can slow the progression of Alzheimer's disease. The clinical benefit achieved in these trials has been modest, however, highlighting the need for both a deeper understanding of disease mechanisms and the importance of intervening early in the pathogenic cascade. An immunoprevention strategy for Alzheimer's disease is required that will integrate the findings from clinical trials with mechanistic insights from preclinical disease models to select promising antibodies, optimize the timing of intervention, identify early biomarkers, and mitigate potential side effects.

Treatment of Alzheimer's Disease: Beyond Symptomatic Therapies

In an ever-increasing aged world, Alzheimer's disease (AD) represents the first cause of dementia and one of the first chronic diseases in elderly people. With 55 million people affected, the WHO considers AD to be a disease with public priority. Unfortunately, there are no final cures for this pathology. Treatment strategies are aimed to mitigate symptoms, i.e., acetylcholinesterase inhibitors (AChEI) and the N-Methyl-D-aspartate (NMDA) antagonist Memantine. At present, the best approaches for managing the disease seem to combine pharmacological and non-pharmacological therapies to stimulate cognitive reserve. Over the last twenty years, a number of drugs have been discovered acting on the well-established biological hallmarks of AD, deposition of β-amyloid aggregates and accumulation of hyperphosphorylated tau protein in cells. Although previous efforts disappointed expectations, a new era in treating AD has been working its way recently. The Food and Drug Administration (FDA) gave conditional approval of the first disease-modifying therapy (DMT) for the treatment of AD, aducanumab, a monoclonal antibody (mAb) designed against Aβ plaques and oligomers in 2021, and in January 2023, the FDA granted accelerated approval for a second monoclonal antibody, Lecanemab. This review describes ongoing clinical trials with DMTs and non-pharmacological therapies. We will also present a future scenario based on new biomarkers that can detect AD in preclinical or prodromal stages, identify people at risk of developing AD, and allow an early and curative treatment.

Synthetic Cell-Based Immunotherapies for Neurologic Diseases

The therapeutic success and widespread approval of genetically engineered T cells for a variety of hematologic malignancies spurred the development of synthetic cell-based immunotherapies for CNS lymphoma, primary brain tumors, and a growing spectrum of nononcologic disease conditions of the nervous system. Chimeric antigen receptor effector T cells bear the potential to deplete target cells with higher efficacy, better tissue penetration, and greater depth than antibody-based cell depletion therapies. In multiple sclerosis and other autoimmune disorders, engineered T-cell therapies are being designed and currently tested in clinical trials for their safety and efficacy to eliminate pathogenic B-lineage cells. Chimeric autoantibody receptor T cells expressing a disease-relevant autoantigen as cell surface domains are designed to selectively deplete autoreactive B cells. Alternative to cell depletion, synthetic antigen-specific regulatory T cells can be engineered to locally restrain inflammation, support immune tolerance, or efficiently deliver neuroprotective factors in brain diseases in which current therapeutic options are very limited. In this article, we illustrate prospects and bottlenecks for the clinical development and implementation of engineered cellular immunotherapies in neurologic diseases.

Optimizing metabolic stability of phosphodiesterase 5 inhibitors: Discovery of a potent N-(pyridin-3-ylmethyl)quinoline derivative targeting synaptic plasticity

Phosphodiesterase 5 (PDE5) is a cyclic guanosine monophosphate-degrading enzyme involved in numerous biological pathways. Inhibitors of PDE5 are important therapeutics for the treatment of neurodegenerative diseases, including Alzheimer's disease (AD). We previously reported the first generation of quinoline-based PDE5 inhibitors for the treatment of AD. However, the short in vitro microsomal stability rendered them unsuitable drug candidates. Here we report a series of new quinoline-based PDE5 inhibitors. Among them, compound 4b, 8-cyclopropyl-3-(hydroxymethyl)-4-(((6-methoxypyridin-3-yl)methyl)amino)quinoline-6-carbonitrile, shows a PDE5 IC50 of 20 nM and improved in vitro microsomal stability (t1/2 = 44.6 min) as well as excellent efficacy in restoring long-term potentiation, a type of synaptic plasticity to underlie memory formation, in electrophysiology experiments with a mouse model of AD. These results provide an insight into the development of a new class of PDE5 inhibitors for the treatment of AD.

Antibody-Mediated Clearance of Brain Amyloid-β: Mechanisms of Action, Effects of Natural and Monoclonal Anti-Aβ Antibodies, and Downstream Effects

Immunotherapeutic efforts to slow the clinical progression of Alzheimer's disease (AD) by lowering brain amyloid-β (Aβ) have included Aβ vaccination, intravenous immunoglobulin (IVIG) products, and anti-Aβ monoclonal antibodies. Neither Aβ vaccination nor IVIG slowed disease progression. Despite conflicting phase III results, the monoclonal antibody Aducanumab received Food and Drug Administration (FDA) approval for treatment of AD in June 2021. The only treatments unequivocally demonstrated to slow AD progression to date are the monoclonal antibodies Lecanemab and Donanemab. Lecanemab received FDA approval in January 2023 based on phase II results showing lowering of PET-detectable Aβ; phase III results released at that time indicated slowing of disease progression. Topline results released in May 2023 for Donanemab's phase III trial revealed that primary and secondary end points had been met. Antibody binding to Aβ facilitates its clearance from the brain via multiple mechanisms including promoting its microglial phagocytosis, activating complement, dissolving fibrillar Aβ, and binding of antibody-Aβ complexes to blood-brain barrier receptors. Antibody binding to Aβ in peripheral blood may also promote cerebral efflux of Aβ by a peripheral sink mechanism. According to the amyloid hypothesis, for Aβ targeting to slow AD progression, it must decrease downstream neuropathological processes including tau aggregation and phosphorylation and (possibly) inflammation and oxidative stress. This review discusses antibody-mediated mechanisms of Aβ clearance, findings in AD trials involving Aβ vaccination, IVIG, and anti-Aβ monoclonal antibodies, downstream effects reported in those trials, and approaches which might improve the Aβ-clearing ability of monoclonal antibodies.

Role of neuroinflammation in neurodegeneration development

Studies in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease and Amyotrophic lateral sclerosis, Huntington's disease, and so on, have suggested that inflammation is not only a result of neurodegeneration but also a crucial player in this process. Protein aggregates which are very common pathological phenomenon in neurodegeneration can induce neuroinflammation which further aggravates protein aggregation and neurodegeneration. Actually, inflammation even happens earlier than protein aggregation. Neuroinflammation induced by genetic variations in CNS cells or by peripheral immune cells may induce protein deposition in some susceptible population. Numerous signaling pathways and a range of CNS cells have been suggested to be involved in the pathogenesis of neurodegeneration, although they are still far from being completely understood. Due to the limited success of traditional treatment methods, blocking or enhancing inflammatory signaling pathways involved in neurodegeneration are considered to be promising strategies for the therapy of neurodegenerative diseases, and many of them have got exciting results in animal models or clinical trials. Some of them, although very few, have been approved by FDA for clinical usage. Here we comprehensively review the factors affecting neuroinflammation and the major inflammatory signaling pathways involved in the pathogenicity of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and Amyotrophic lateral sclerosis. We also summarize the current strategies, both in animal models and in the clinic, for the treatment of neurodegenerative diseases.

Targeting apolipoprotein E and N-terminal amyloid β-protein precursor interaction improves cognition and reduces amyloid pathology in Alzheimer's mice

Apolipoprotein E (apoE) interaction with amyloid β-protein precursor (APP) has garnered attention as the therapeutic target for Alzheimer's disease (AD). Having discovered the apoE antagonist (6KApoEp) that blocks apoE binding to N-terminal APP, we tested the therapeutic potential of 6KApoEp on AD-relevant phenotypes in amyloid β-protein precursor/presenilin 1 (APP/PS1) mice that express each human apoE isoform of apoE2, apoE3, or apoE4 (designated APP/PS1/E2, APP/PS1/E3, or APP/PS1/E4 mice). At 12 months of age, we intraperitoneally administered 6KApoEp (250 μg/kg) or vehicle once daily for 3 months. At 15 months of age, blockage of apoE and N-terminal APP interaction by 6KApoEp treatment improved cognitive impairment in most tests of learning and memory, including novel object recognition and maze tasks in APP/PS1/E2, APP/PS1/E3, and APP/PS1/E4 mice versus each vehicle-treated mouse line and did not alter behavior in nontransgenic littermates. Moreover, 6KApoEp therapy ameliorated brain parenchymal and cerebral vascular β-amyloid deposits and decreased abundance of amyloid β-protein (Aβ) in APP/PS1/E2, APP/PS1/E3, and APP/PS1/E4 mice versus each vehicle-treated mouse group. Notably, the highest effect in Aβ-lowering by 6KApoEp treatment was observed in APP/PS1/E4 mice versus APP/PS1/E2 or APP/PS1/E3 mice. These effects occured through shifting toward lessened amyloidogenic APP processing due to decreasing APP abundance at the plasma membrane, reducing APP transcription, and inhibiting p44/42 mitogen-activated protein kinase phosphorylation. Our findings provide the preclinical evidence that 6KApoEp therapy aimed at targeting apoE and N-terminal APP interaction is a promising strategy and may be suitable for patients with AD carrying the apoE4 isoform.

Alzheimer's Disease: Treatment Today and Tomorrow

Background and Aims

The scope of treatment in Alzheimer's Disease has widened in recent times with FDA approval of new drugs. This review looks at established treatments in AD as well as critically analyses the newer drugs available.

Methods

Data in this review was gathered from PubMed; Google Scholar and MEDLINE from January-March 2023. Search words used were 'Alzheimer's Disease treatment' and 'Dementia treatment'.

Results

Older time tested drugs like Acetyl Choline Receptor Inhibitors and NMDA Receptor antagonists remain the mainstay of pharmacological treatment in AD. Despite a lot of excitement about newer FDA approved drugs; we have to be cautious in their use. Aducanumab showed good reduction in CSF amyloid levels (biomarker of AD); but this did not necessarily translate into better clinical outcomes of patients.

Conclusion

Despite the recent advances and approval of drugs in treatment of AD, we have to exhibit caution while prescribing these drugs. Even with a sound mechanism of action, these drugs do not always show improvement in clinical outcomes. More clinical trials are required for development of drugs in treatment of AD which explore various different mechanisms of action.

Recent Trends in Active and Passive Immunotherapies of Alzheimer's Disease

In the elderly, a debilitating condition known as dementia, which is a major health concern, is caused by Alzheimer's disease (AD). Despite promising advances by researchers, there is currently no way to completely cure this devastating disease. It is illustrated by the deposition of amyloid β-peptide (Aβ) plaques that are followed by neural dysfunction and cognitive decline. Responses against AD activate an immune system that contributes to and accelerates AD pathogenesis. Potential efforts in the field of pathogenesis have prompted researchers to explore novel therapies such as active and passive vaccines against Aβ proteins (Aβ immunotherapy), intravenous immunoglobulin, and tau immunotherapy, as well as targets that include microglia and several cytokines for the treatment of AD. Aims are now underway by experts to begin immunotherapies before the clinical manifestation, which is made possible by improving the sensitivity of biomarkers used for the diagnosis of AD to have better outcome measures. This review provides an overview of approved immunotherapeutic strategies for AD and those currently being investigated in clinical trials. We examine their mechanisms of action and discuss the potential perspectives and challenges associated with immunotherapies for AD.

Novel Vaccine against Pathological Pyroglutamate-Modified Amyloid Beta for Prevention of Alzheimer's Disease

Post-translationally modified N-terminally truncated amyloid beta peptide with a cyclized form of glutamate at position 3 (pE3Aβ) is a highly pathogenic molecule with increased neurotoxicity and propensity for aggregation. In the brains of Alzheimer's Disease (AD) cases, pE3Aβ represents a major constituent of the amyloid plaque. The data show that pE3Aβ formation is increased at early pre-symptomatic disease stages, while tau phosphorylation and aggregation mostly occur at later stages of the disease. This suggests that pE3Aβ accumulation may be an early event in the disease pathogenesis and can be prophylactically targeted to prevent the onset of AD. The vaccine (AV-1986R/A) was generated by chemically conjugating the pE3Aβ3-11 fragment to our universal immunogenic vaccine platform MultiTEP, then formulated in AdvaxCpG adjuvant. AV-1986R/A showed high immunogenicity and selectivity, with endpoint titers in the range of 105-106 against pE3Aβ and 103-104 against the full-sized peptide in the 5XFAD AD mouse model. The vaccination showed efficient clearance of the pathology, including non-pyroglutamate-modified plaques, from the mice brains. AV-1986R/A is a novel promising candidate for the immunoprevention of AD. It is the first late preclinical candidate which selectively targets a pathology-specific form of amyloid with minimal immunoreactivity against the full-size peptide. Successful translation into clinic may offer a new avenue for the prevention of AD via vaccination of cognitively unimpaired individuals at risk of disease.