A Phase II study targeting amyloid- with 3APS in mild-to-moderate Alzheimer disease

Clinical Pharmacokinetics of Oral ALZ-801/Valiltramiprosate in a 2-Year Phase 2 Trial of APOE4 Carriers with Early Alzheimer's Disease

INTRODUCTION

ALZ-801/valiltramiprosate is an oral, small-molecule inhibitor of β-amyloid (Aβ) oligomer formation in late-stage development as a potential disease-modifying therapy for Alzheimer's disease (AD). ALZ-801, a valine-conjugated prodrug, is rapidly converted to tramiprosate after oral dosing. Upon conversion to tramiprosate, it generates a single metabolite, 3-sulfopropanoic acid (3-SPA). Both tramiprosate and 3-SPA are active anti-Aβ oligomer agents that mediate ALZ-801's central mechanism of action (MOA). We summarize herein the pharmacokinetics (PK) of ALZ-801 in apolipoprotein ε4 (APOE4) carrier subjects with early AD from a phase 2 trial.

METHODS

The ALZ-801 phase 2 study was designed to evaluate longitudinal effects of ALZ-801 (265 mg BID) on plasma, cerebrospinal fluid (CSF) and volumetric magnetic resonance imaging (MRI) AD biomarkers, and clinical outcomes over 104 weeks in APOE4 carriers with early AD. Eighty-four subjects (31 APOE4/4 homozygotes and 53 APOE3/4 heterozygotes) with positive CSF biomarkers of amyloid and tau pathology were enrolled. The phase 2 study included a substudy of 24 subjects to provide 8-h steady-state PK at 65 weeks. Sparse PK samples were also analyzed. The relationships between plasma PK exposure and clinical characteristics [i.e., sex, APOE genotype, age, body mass index (BMI), estimated glomerular filtration rate (eGFR), concomitant acetylcholinesterase inhibitor (AChEI) use, and tablet lot] were evaluated.

RESULTS

The steady-state plasma PK results were closely aligned with the previous 2-week PK in the ALZ-801 phase 1b study in APOE4 carrier subjects with AD, as well as a phase 1 7-day PK study in heathy elderly volunteers. Following oral dosing, ALZ-801 was rapidly converted to the active moieties, tramiprosate and 3-SPA. The intersubject variability in plasma drug levels was low, confirming the superior performance of ALZ-801 versus oral tramiprosate tablet (150 mg BID) from the earlier tramiprosate phase 3 trials. Correlation analysis versus clinical characteristics showed that plasma exposures (Cmax and AUC8h) for ALZ-801, tramiprosate, and 3-SPA were not affected by sex, APOE genotype, age, BMI, concomitant AChEI use, or tablet lot. Plasma exposures of both tramiprosate and 3-SPA, but not ALZ-801, were inversely correlated with eGFR, in line with renal excretion as the primary route of elimination. ALZ-801 was well tolerated without new safety signals or events of amyloid-related imaging abnormalities (ARIA).

CONCLUSIONS

The steady-state PK profile of oral ALZ-801 in subjects with early AD was not affected by sex, APOE genotype, age, BMI, concomitant use of AChEI, or tablet lot. The inverse relationship of plasma exposures of tramiprosate and 3-SPA, but not ALZ-801, versus eGFR is consistent with renal clearance as the primary route of elimination for tramiprosate and 3-SPA (active moieties), and with the efficient conversion of ALZ-801 prodrug to the active moieties after dosing. These results demonstrate that ALZ-801 displays favorable PK properties without evidence of interactions with demographic characteristics and support its development as an oral disease-modifying treatment for AD.

TRIAL REGISTRATION

https://clinicaltrials.gov/study/NCT04693520 .

Trajectory of brain-derived amyloid beta in Alzheimer's disease: where is it coming from and where is it going?

Alzheimer's disease (AD) is a progressive neurological disorder that primarily impacts cognitive function. Currently there are no disease-modifying treatments to stop or slow its progression. Recent studies have found that several peripheral and systemic abnormalities are associated with AD, and our understanding of how these alterations contribute to AD is becoming more apparent. In this review, we focuse on amyloid‑beta (Aβ), a major hallmark of AD, summarizing recent findings on the source of brain-derived Aβ and discussing where and how the brain-derived Aβ is cleared in vivo. Based on these findings, we propose future strategies for AD prevention and treatment, from a novel perspective on Aβ metabolism.

Analysis of Cerebrospinal Fluid, Plasma β-Amyloid Biomarkers, and Cognition from a 2-Year Phase 2 Trial Evaluating Oral ALZ-801/Valiltramiprosate in APOE4 Carriers with Early Alzheimer's Disease Using Quantitative Systems Pharmacology Model

INTRODUCTION

ALZ-801/valiltramiprosate is an oral, small-molecule inhibitor of beta-amyloid (Aβ) aggregation and oligomer formation in late-stage development as a disease-modifying therapy for early Alzheimer's disease (AD). The present investigation provides a quantitative systems pharmacology (QSP) analysis of amyloid fluid biomarkers and cognitive results from a 2-year ALZ-801 Phase 2 trial in APOE4 carriers with early AD.

METHODS

The single-arm, open-label phase 2 study evaluated effects of ALZ-801 265 mg two times daily (BID) on cerebrospinal fluid (CSF) and plasma amyloid fluid biomarkers over 104 weeks in APOE4 carriers with early AD [Mini-Mental State Examination (MMSE) ≥ 22]. Subjects with positive CSF biomarkers for amyloid (Aβ42/Aβ40) and tau pathology (p-tau181) were enrolled, with serial CSF and plasma levels of Aβ42 and Aβ40 measured over 104 weeks. Longitudinal changes of CSF Aβ42, plasma Aβ42/Aβ40 ratio, and cognitive Rey Auditory Verbal Learning Test (RAVLT) were compared with the established natural disease trajectories in AD using a QSP approach. The natural disease trajectory data for amyloid biomarkers and RAVLT were extracted from a QSP model and an Alzheimer's disease neuroimaging initiative population model, respectively. Analyses were stratified by disease severity and sex.

RESULTS

A total of 84 subjects were enrolled. Excluding one subject who withdrew at the early stage of the trial, data from 83 subjects were used for this analysis. The ALZ-801 treatment arrested the progressive decline in CSF Aβ42 level and plasma Aβ42/Aβ40 ratio, and stabilized RAVLT over 104 weeks. Both sexes showed comparable responses to ALZ-801, whereas mild cognitive impairment (MCI) subjects (MMSE ≥ 27) exhibited a larger biomarker response compared with more advanced mild AD subjects (MMSE 22-26).

CONCLUSIONS

In this genetically defined and biomarker-enriched early AD population, the QSP analysis demonstrated a positive therapeutic effect of oral ALZ-801 265 mg BID by arresting the natural decline of monomeric CSF and plasma amyloid biomarkers, consistent with the target engagement to prevent their aggregation into soluble neurotoxic oligomers and subsequently into insoluble fibrils and plaques over 104 weeks. Accompanying the amyloid biomarker changes, ALZ-801 also stabilized the natural trajectory decline of the RAVLT memory test, suggesting that the clinical benefits are consistent with its mechanism of action. This sequential effect arresting the disease progression on biomarkers and cognitive decline was more pronounced in the earlier symptomatic stages of AD. The QSP analysis provides fluid biomarker and clinical evidence for ALZ-801 as a first-in-class, oral small-molecule anti-Aβ oligomer agent with disease modification potential in AD.

TRIAL REGISTRY

https://clinicaltrials.gov/study/NCT04693520.

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.

The Unveiling of Therapeutic Targets for Alzheimer's Disease: An Integrative Review

Alzheimer's disease (AD) is characterized by a complex pathological landscape, necessitating a comprehensive treatment approach. This concise review paper delves into the idea of addressing multiple mechanisms in AD, summarizing the latest research findings on pathogenesis, risk factors, diagnostics, and therapeutic strategies. The etiology of AD is multifaceted, involving genetic, environmental, and lifestyle factors. The primary feature is the accumulation of amyloid-- beta and tau proteins, leading to neuroinflammation, synaptic dysfunction, oxidative stress, and neuronal loss. Conventional single-target therapies have shown limited effectiveness, prompting a shift toward simultaneously addressing multiple disease-related processes. Recent advancements in AD research underscore the potential of multifaceted therapies. This review explores strategies targeting both tau aggregation and amyloid-beta, along with interventions to alleviate neuroinflammation, enhance synaptic function, and reduce oxidative stress. In conclusion, the review emphasizes the growing importance of addressing various pathways in AD treatment. A holistic approach that targets different aspects of the disease holds promise for developing effective treatments and improving the quality of life for Alzheimer's patients and their caregivers.

Molecular Mechanism of Tau Misfolding and Aggregation: Insights from Molecular Dynamics Simulation

Tau dysfunction has a close association with many neurodegenerative diseases, which are collectively referred to as tauopathies. Neurofibrillary tangles (NFTs) formed by misfolding and aggregation of tau are the main pathological process of tauopathy. Therefore, uncovering the misfolding and aggregation mechanism of tau protein will help to reveal the pathogenic mechanism of tauopathies. Molecular dynamics (MD) simulation is well suited for studying the dynamic process of protein structure changes. It provides detailed information on protein structure changes over time at the atomic resolution. At the same time, MD simulation can also simulate various conditions conveniently. Based on these advantages, MD simulations are widely used to study conformational transition problems such as protein misfolding and aggregation. Here, we summarized the structural features of tau, the factors affecting its misfolding and aggregation, and the applications of MD simulations in the study of tau misfolding and aggregation.

Comprehensive Insights into Pathophysiology of Alzheimer's Disease: Herbal Approaches for Mitigating Neurodegeneration

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, memory loss, and functional impairment. Despite extensive research, the exact etiology remains elusive. This review explores the multifaceted pathophysiology of AD, focusing on key hypotheses such as the cholinergic hypothesis, hyperphosphorylated Tau Protein and Amyloid β hypothesis, oxidative stress hypothesis, and the metal ion hypothesis. Understanding these mechanisms is crucial for developing effective therapeutic strategies. Current treatment options for AD have limitations, prompting the exploration of alternative approaches, including herbal interventions. Cholinesterase inhibitors, targeting the cholinergic hypothesis, have shown modest efficacy in managing symptoms. Blocking Amyloid β (Aβ) and targeting hyperphosphorylated tau protein are under investigation, with limited success in clinical trials. Oxidative stress, implicated in AD pathology, has led to the investigation of antioxidants. Natural products, such as Punica granatum Linn, Radix Scutellariae, and Curcuma longa have demonstrated antioxidant properties, along with anti-inflammatory effects, offering potential neuroprotective benefits. Several herbal extracts, including Ginkgo biloba, Bacopa monnieri, and Withania somnifera, have shown promise in preclinical studies. Compounds like Huperzine A, Melatonin, and Bryostatin exhibit neuroprotective effects through various mechanisms, including cholinergic modulation and anti-inflammatory properties. However, the use of herbal drugs for AD management faces limitations, including standardization issues, variable bioavailability, and potential interactions with conventional medications. Additionally, the efficacy and safety of many herbal products remain to be established through rigorous clinical trials. This review also highlights promising natural products currently in clinical trials, such as Resveratrol and Homotaurine, and their potential impact on AD progression. DHA, an omega-3 fatty acid, has shown cognitive benefits, while Nicotine is being explored for its neuroprotective effects. In conclusion, a comprehensive understanding of the complex pathophysiology of AD and the exploration of herbal interventions offer a holistic approach for managing this devastating disease. Future research should address the limitations associated with herbal drugs and further evaluate the efficacy of promising natural products in clinical settings.

Effects of three kinds of anti-amyloid-β drugs on clinical, biomarker, neuroimaging outcomes and safety indexes: A systematic review and meta-analysis of phase II/III clinical trials in Alzheimer's disease

OBJECTIVE

To investigate the effects of the three kinds of anti-amyloid-β (Aβ) drugs on cognitive and other functions, fluid and neuroimaging biomarkers, and safety on patients with Alzheimer's disease (AD), and rank the three kinds of anti-Aβ drugs.

METHODS

We searched Medline, Embase, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and AlzForum from inception to January 21, 2023 to include randomized controlled clinical trials. Random effects meta-analyses were performed.

RESULTS

Forty-one clinical trials (20929 participants, 9167 male) were included. Anti-Aβ drugs had significant but relatively low efficacy in preventing cognitive decline (ADAS-Cog SMD -0.07, 95% CI: -0.10 to -0.03, p < 0.001; CDR-SOB -0.05, -0.09 to -0.01, p = 0.017). Instrumental variable meta-analysis and trial sequential analysis confirmed the reliability of the pooled estimation. Beneficial effects were also observed by assessing other cognitive and activity of daily living scales and biomarkers, with acceptable safety of anti-Aβ drugs. Meta-regression demonstrated significant association between higher baseline mini-mental statement examination scores (MMSE) and better cognitive protective effects on cognitive function (ADAS-Cog β: -0.02, -0.05 to 0.00, p = 0.017) and clearance of pathological productions of anti-Aβ drugs. Network meta-analysis ranked the passive immunotherapy drugs to have the best cognitive efficacy, followed by active immunotherapy and small molecule drugs.

CONCLUSION

Anti-Aβ drugs have relatively low efficacy in preventing cognitive decline, and they reduce pathological productions with acceptable safety. Patients with higher baseline MMSE scores benefit more from anti-Aβ drugs. Passive immunotherapy anti-Aβ drugs show relatively better efficacy than active immunotherapy and small molecule anti-Aβ drugs.

Chaperone Activity and Protective Effect against Aβ-Induced Cytotoxicity of Artocarpus camansi Blanco and Amaranthus dubius Mart. ex Thell Seed Protein Extracts

Alzheimer's disease (AD) is the most common type of dementia and is listed as the sixth-leading cause of death in the United States. Recent findings have linked AD to the aggregation of amyloid beta peptides (Aβ), a proteolytic fragment of 39-43 amino acid residues derived from the amyloid precursor protein. AD has no cure; thus, new therapies to stop the progression of this deadly disease are constantly being searched for. In recent years, chaperone-based medications from medicinal plants have gained significant interest as an anti-AD therapy. Chaperones are responsible for maintaining the three-dimensional shape of proteins and play an important role against neurotoxicity induced by the aggregation of misfolded proteins. Therefore, we hypothesized that proteins extracted from the seeds of Artocarpus camansi Blanco (A. camansi) and Amaranthus dubius Mart. ex Thell (A. dubius) could possess chaperone activity and consequently may exhibit a protective effect against Aβ_1-40-induced cytotoxicity. To test this hypothesis, the chaperone activity of these protein extracts was measured using the enzymatic reaction of citrate synthase (CS) under stress conditions. Then, their ability to inhibit the aggregation of Aβ_1-40 using a thioflavin T (ThT) fluorescence assay and DLS measurements was determined. Finally, the neuroprotective effect against Aβ_1-40 in SH-SY5Y neuroblastoma cells was evaluated. Our results demonstrated that A. camansi and A. dubius protein extracts exhibited chaperone activity and inhibited Aβ_1-40 fibril formation, with A. dubius showing the highest chaperone activity and inhibition at the concentration assessed. Additionally, both protein extracts showed neuroprotective effects against Aβ_1-40-induced toxicity. Overall, our data demonstrated that the plant-based proteins studied in this research work can effectively overcome one of the most important characteristics of AD.

Application of Marine Natural Products against Alzheimer's Disease: Past, Present and Future

Alzheimer's disease (AD), a neurodegenerative disease, is one of the most intractable illnesses which affects the elderly. Clinically manifested as various impairments in memory, language, cognition, visuospatial skills, executive function, etc., the symptoms gradually aggravated over time. The drugs currently used clinically can slow down the deterioration of AD and relieve symptoms but cannot completely cure them. The drugs are mainly acetylcholinesterase inhibitors (AChEI) and non-competitive N-methyl-D-aspartate receptor (NDMAR) antagonists. The pathogenesis of AD is inconclusive, but it is often associated with the expression of beta-amyloid. Abnormal deposition of amyloid and hyperphosphorylation of tau protein in the brain have been key targets for past, current, and future drug development for the disease. At present, researchers are paying more and more attention to excavate natural compounds which can be effective against Alzheimer's disease and other neurodegenerative pathologies. Marine natural products have been demonstrated to be the most prospective candidates of these compounds, and some have presented significant neuroprotection functions. Consequently, we intend to describe the potential effect of bioactive compounds derived from marine organisms, including polysaccharides, carotenoids, polyphenols, sterols and alkaloids as drug candidates, to further discover novel and efficacious drug compounds which are effective against AD.

Toward Prevention and Reduction of Alzheimer's Disease

Different investigations lead to the urgent need to generate validated clinical protocols as a tool for medical doctors to orientate patients under risk for a preventive approach to control Alzheimer's disease. Moreover, there is consensus that the combined effects of risk factors for the disease can be modified according to lifestyle, thus controlling at least 40% of cases. The other fraction of cases are derived from candidate genes and epigenetic components as a relevant factor in AD pathogenesis. At this point, it appears to be of critical relevance the search for molecular biomarkers that may provide information on probable pathological events and alert about early detectable risks to prevent symptomatic events of the disease. These precocious detection markers will then allow early interventions of non-symptomatic subjects at risk. Here, we summarize the status and potential avenues of prevention and highlight the usefulness of biological and reliable markers for AD.

Alzheimer's disease failed clinical trials

Alzheimer's disease is a progressive neurodegenerative disease typically presenting with symptoms of memory loss and cognitive decline. Existing theories for the causation of this focuses on amyloid beta plaques and neurofibrillary tau tangles. Most US Food and Drug Administration approved therapies for Alzheimer's disease target cognitive function. A multitude of clinical trials, with a variety of different targets have been conducted over the decades which have focused on the two clinical signs, with the only success being the controversial 2021 approval of an IgG1 anti-Ab antibody targeting the clearance of the Aβ plaques. Presented is a review of all previously failed Alzheimer's disease clinical trials and the rationale for their failures.

Physiological Roles of Monomeric Amyloid-β and Implications for Alzheimer's Disease Therapeutics

Alzheimer's disease (AD) progressively inflicts impairment of synaptic functions with notable deposition of amyloid-β (Aβ) as senile plaques within the extracellular space of the brain. Accordingly, therapeutic directions for AD have focused on clearing Aβ plaques or preventing amyloidogenesis based on the amyloid cascade hypothesis. However, the emerging evidence suggests that Aβ serves biological roles, which include suppressing microbial infections, regulating synaptic plasticity, promoting recovery after brain injury, sealing leaks in the blood-brain barrier, and possibly inhibiting the proliferation of cancer cells. More importantly, these functions were found in in vitro and in vivo investigations in a hormetic manner, that is to be neuroprotective at low concentrations and pathological at high concentrations. We herein summarize the physiological roles of monomeric Aβ and current Aβ-directed therapies in clinical trials. Based on the evidence, we propose that novel therapeutics targeting Aβ should selectively target Aβ in neurotoxic forms such as oligomers while retaining monomeric Aβ in order to preserve the physiological functions of Aβ monomers.

Prodrug Therapies for Infectious and Neurodegenerative Diseases

Prodrugs are bioreversible drug derivatives which are metabolized into a pharmacologically active drug following chemical or enzymatic modification. This approach is designed to overcome several obstacles that are faced by the parent drug in physiological conditions that include rapid drug metabolism, poor solubility, permeability, and suboptimal pharmacokinetic and pharmacodynamic profiles. These suboptimal physicochemical features can lead to rapid drug elimination, systemic toxicities, and limited drug-targeting to disease-affected tissue. Improving upon these properties can be accomplished by a prodrug design that includes the careful choosing of the promoiety, the linker, the prodrug synthesis, and targeting decorations. We now provide an overview of recent developments and applications of prodrugs for treating neurodegenerative, inflammatory, and infectious diseases. Disease interplay reflects that microbial infections and consequent inflammation affects neurodegenerative diseases and vice versa, independent of aging. Given the high prevalence, personal, social, and economic burden of both infectious and neurodegenerative disorders, therapeutic improvements are immediately needed. Prodrugs are an important, and might be said a critical tool, in providing an avenue for effective drug therapy.

Computational Insights Into the Inhibition Mechanism of Proanthocyanidin B2 on Tau Hexapeptide (PHF6) Oligomer

The formation of amyloid fibrils from Tau is a key pathogenic feature of Alzheimer's disease (AD). To disturb the formation of Tau aggregates is considered as a promising therapeutic strategy for AD. Recently, a natural product proanthocyanidin B2 (PB2) was confirmed to not only inhibit Tau aggregation, but also disaggregate Tau fibrils. Herein, to explore the inhibition mechanism of PB2 against Tau fibril and to provide the useful information for drug design and discovery, all-atom molecular dynamics simulations were carried out for the ordered Tau hexapeptide PHF6 oligomer in the presence and absence of PB2. The obtained result shows that PB2 can transform PHF6 oligomer from the ordered β-sheet structure into disordered one. Moreover, the clustering analysis and binding free energy calculations identify that S3 site is the most potential binding site. At S3 site, by hydrophobic and hydrogen bond interactions, the residues V309, Y310 and K311 are essential for binding with PB2, especially K311. In a word, our study reveals the molecular mechanism of PB2 inhibiting PHF6 aggregation and it will provide some valuable information for the development of Tau aggregation inhibitors.

Anti-Alzheimer's Molecules Derived from Marine Life: Understanding Molecular Mechanisms and Therapeutic Potential

Alzheimer's disease (AD) is a devastating neurodegenerative disease and the most common cause of dementia. It has been confirmed that the pathological processes that intervene in AD development are linked with oxidative damage to neurons, neuroinflammation, tau phosphorylation, amyloid beta (Aβ) aggregation, glutamate excitotoxicity, and cholinergic deficit. Still, there is no available therapy that can cure AD. Available therapies only manage some of the AD symptoms at the early stages of AD. Various studies have revealed that bioactive compounds derived from marine organisms and plants can exert neuroprotective activities with fewer adverse events, as compared with synthetic drugs. Furthermore, marine organisms have been identified as a source of novel compounds with therapeutic potential. Thus, there is a growing interest regarding bioactive compounds derived from marine sources that have anti-AD potentials. Various marine drugs including bryostatin-1, homotaurine, anabaseine and its derivative, rifampicins, anhydroexfoliamycin, undecylprodigioisin, gracilins, 13-desmethyl spirolide-C, and dictyostatin displayed excellent bioavailability and efficacy against AD. Most of these marine drugs were found to be well-tolerated in AD patients, along with no significant drug-associated adverse events. In this review, we focus on the drugs derived from marine life that can be useful in AD treatment and also summarize the therapeutic agents that are currently used to treat AD.

Curcumin and Homotaurine Suppress Amyloid-β25-35 Aggregation in Synthetic Brain Membranes

Amyloid-β (Aβ) peptides spontaneously aggregate into β- and cross-β-sheets in model brain membranes. These nanometer sized can fuse into larger micrometer sized clusters and become extracellular and serve as nuclei for further plaque and fibril growth. Curcumin and homotaurine represent two different types of Aβ aggregation inhibitors. While homotaurine is a peptic antiaggregant that binds to amyloid peptides, curcumin is a nonpeptic molecule that can inhibit aggregation by changing membrane properties. By using optical and fluorescent microscopy, X-ray diffraction, and UV-vis spectroscopy, we study the effect of curcumin and homotaurine on Aβ_25-35 aggregates in synthetic brain membranes. Both molecules partition spontaneously and uniformly in membranes and do not lead to observable membrane defects or disruption in our experiments. Both curcumin and homotaurine were found to significantly reduce the number of small, nanoscopic Aβ aggregates and the corresponding β- and cross-β-sheet signals. While a number of research projects focus on potential drug candidates that target Aβ peptides directly, membrane-lipid therapy explores membrane-mediated pathways to suppress peptide aggregation. Based on the results obtained, we conclude that membrane active drugs can be as efficient as peptide targeting drugs in inhibiting amyloid aggregation in vitro.

Sulfur-containing therapeutics in the treatment of Alzheimer's disease

Sulfur is widely existent in natural products and synthetic organic compounds as organosulfur, which are often associated with a multitude of biological activities. OBenzothiazole, in which benzene ring is fused to the 4,5-positions of the thiazolerganosulfur compounds continue to garner increasing amounts of attention in the field of medicinal chemistry, especially in the development of therapeutic agents for Alzheimer's disease (AD). AD is a fatal neurodegenerative disease and the primary cause of age-related dementia posing severe societal and economic burdens. Unfortunately, there is no cure for AD. A lot of research has been conducted on sulfur-containing compounds in the context of AD due to their innate antioxidant potential and some are currently being evaluated in clinical trials. In this review, we have described emerging trends in the field, particularly the concept of multi-targeting and formulation of disease-modifying strategies. SAR, pharmacological targets, in vitro/vivo ADMET, efficacy in AD animal models, and applications in clinical trials of such sulfur compounds have also been discussed. This article provides a comprehensive review of organosulfur-based AD therapeutic agents and provides insights into their future development.

Evaluation of the neuroprotective effect of taurine in Alzheimer's disease using functional molecular imaging

Alzheimer's disease (AD) is a chronic neurodegenerative disorder and the leading cause of dementia, but therapeutic treatment options are limited. Taurine has been reported to have neuroprotective properties against dementia, including AD. The present study aimed to investigate the treatment effect of taurine in AD mice by functional molecular imaging. To elucidate glutamate alterations by taurine, taurine was administered to 5xFAD transgenic mice from 2 months of age, known to apear amyloid deposition. Then, we performed glutamate positron emission tomography (PET) imaging studies for three groups (wild-type, AD, and taurine-treated AD, n = 5 in each group). As a result, brain uptake in the taurine-treated AD group was 31-40% higher than that in the AD group (cortex: 40%, p < 0.05; striatum: 32%, p < 0.01; hippocampus: 36%, p < 0.01; thalamus: 31%, p > 0.05) and 3-14% lower than that in the WT group (cortex: 10%, p > 0.05; striatum: 15%, p > 0.05; hippocampus: 14%, p > 0.05; thalamus: 3%, p > 0.05). However, we did not observe differences in Aβ pathology between the taurine-treated AD and AD groups in immunohistochemistry experiments. Our results reveal that although taurine treatment did not completely recover the glutamate system, it significantly increased metabolic glutamate receptor type 5 brain uptake. Therefore, taurine has therapeutic potential against 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.

A Review on Tramiprosate (Homotaurine) in Alzheimer's Disease and Other Neurocognitive Disorders

Alzheimer's disease (AD) is the most prevalent neurodegenerative condition, especially among elderly people. The presence of cortical β-amyloid deposition, together with tau phosphorylation and intracellular accumulation of neurofibrillary tangles (NFT) is the main neuropathologic criteria for AD diagnosis. Additionally, a role of inflammatory, mitochondrial, and metabolic factors has been suggested. Tramiprosate binds to soluble amyloid, thus inhibiting its aggregation in the brain. It reduced oligomeric and fibrillar (plaque) amyloid, diminished hippocampal atrophy, improved cholinergic transmission, and stabilized cognition in preclinical and clinical studies. In this narrative review, current information on the efficacy and safety of tramiprosate, both in AD and in other neurocognitive disorders, is presented. Possible directions for future studies with tramiprosate are also discussed.

GABAergic dysfunction in excitatory and inhibitory (E/I) imbalance drives the pathogenesis of Alzheimer's disease

OBJECTIVE

To propose a new hypothesis that GABAergic dysfunction in excitatory and inhibitory (E/I) imbalance drives the pathogenesis of Alzheimer's disease (AD).

BACKGROUND

Synaptic dysfunction and E/I imbalance emerge decades before the appearance of cognitive decline in AD patients, which contribute to neurodegeneration. Initially, E/I imbalance was thought to occur first, due to dysfunction of the glutamatergic and cholinergic systems. However, new evidence has demonstrated that the GABAergic system, the counterpart of E/I balance and the major inhibitory neurotransmitter system in the central nervous system, is altered enormously and that this contributes to E/I imbalance and further AD pathogenesis.

NEW HYPOTHESIS

Alterations to the GABAergic system, induced by multiple AD pathogenic or risk factors, contribute to E/I imbalance and AD pathogenesis.

MAJOR CHALLENGES FOR THE HYPOTHESIS

This GABAergic hypothesis accounts for many critical questions and common challenges confronting a new hypothesis of AD pathogenesis. More specifically, it explains why amyloid beta (Aβ), β-secretase (BACE1), apolipoprotein E4 gene (APOE ε4), hyperactive glia cells, contributes to AD pathogenesis and why age and sex are the risk factors of AD. GABAergic dysfunction promotes the spread of Aβ pathology throughout the AD brain and associated cognitive impairments, and the induction of dysfunction induced by these varied risk factors shares this common neurobiology leading to E/I imbalance. In turn, some of these factors exacerbate GABAergic dysfunction and E/I imbalance. Moreover, the GABAergic system modulates various brain functions and thus, the GABAergic hypothesis accounts for nonamnestic manifestations. Furthermore, corrections of E/I balance through manipulation of GABAergic functions have shown positive outcomes in preclinical and clinical studies, suggesting the potential of the GABAergic system as a therapeutic target in AD.

LINKAGE TO OTHER MAJOR THEORIES

Dysfunction of the GABAergic system is induced by multiple critical signaling pathways, which include the existing major theories of AD pathogenesis, such as the Aβ and neuroinflammation hypotheses. In a new perspective, this GABAergic hypothesis accounts for the E/I imbalance and related excitotoxicity, which contribute to cognitive decline and AD pathogenesis. Therefore, the GABAergic system could be a key target to restore, at least partially, the E/I balance and cognitive function in AD patients.

Study of the noncovalent interactions of ginsenosides and amyloid-β-peptide by CSI-MS and molecular docking

Noncovalent interactions between drugs and proteins play significant roles for drug metabolisms and drug discoveries. Mass spectrometry has been a commonly used method for studying noncovalent interactions. However, the harsh ionization process in electrospray ionization mass spectrometry (ESI-MS) is not conducive to the preservation of noncovalent and unstable biomolecular complexes compared with the cold spray ionization mass spectrometry (CSI-MS). A cold spray ionization providing a stable solvation-ionization at low temperature is milder than ESI, which was more suitable for studying noncovalent drug-protein complexes with exact stoichiometries. In this paper, we apply CSI-MS to explore the interactions of ginsenosides toward amyloid-β-peptide (Aβ) and clarify the therapeutic effect of ginsenosides on Alzheimer's disease (AD) at the molecular level for the first time. The interactions of ginsenosides with Aβ were performed by CSI-MS and ESI-MS, respectively. The ginsenosides Rg1 bounded to Aβ at the stoichiometries of 1:1 to 5:1 could be characterized by CSI-MS, while dehydration products are more readily available by ESI-MS. The binding force depends on the number of glycosyls and the type of ginsenosides. The relative binding affinities were sorted in order as follows: Rg1 ≈ Re > Rd ≈ Rg2 > Rh2, protopanaxatriol by competition experiments, which were supported by molecular docking experiment. CSI-MS is expected to be a more appropriate approach to determine the weak but specific interactions of proteins with other natural products especially polyhydroxy compounds.

Homotaurine Treatment Enhances CD4+ and CD8+ Regulatory T Cell Responses and Synergizes with Low-Dose Anti-CD3 to Enhance Diabetes Remission in Type 1 Diabetic Mice

Immune cells express γ-aminobutyric acid receptors (GABA-R), and GABA administration can inhibit effector T cell responses in models of autoimmune disease. The pharmacokinetic properties of GABA, however, may be suboptimal for clinical applications. The amino acid homotaurine is a type A GABA-R (GABAA-R) agonist with good pharmacokinetics and appears safe for human consumption. In this study, we show that homotaurine inhibits in vitro T cell proliferation to a similar degree as GABA but at lower concentrations. In vivo, oral homotaurine treatment had a modest ability to reverse hyperglycemia in newly hyperglycemic NOD mice but was ineffective after the onset of severe hyperglycemia. In severely diabetic NOD mice, the combination of homotaurine and low-dose anti-CD3 treatment significantly increased 1) disease remission, 2) the percentages of splenic CD4+and CD8+ regulatory T cells compared with anti-CD3 alone, and 3) the frequencies of CD4+ and CD8+ regulatory T cells in the pancreatic lymph nodes compared with homotaurine monotherapy. Histological examination of their pancreata provided no evidence of the large-scale GABAA-R agonist-mediated replenishment of islet β-cells that has been reported by others. However, we did observe a few functional islets in mice that received combined therapy. Thus, GABAA-R activation enhanced CD4+and CD8+ regulatory T cell responses following the depletion of effector T cells, which was associated with the preservation of some functional islets. Finally, we observed that homotaurine treatment enhanced β-cell replication and survival in a human islet xenograft model. Hence, GABAA-R agonists, such as homotaurine, are attractive candidates for testing in combination with other therapeutic agents in type 1 diabetes clinical trials.

Mobile obstacles accelerate and inhibit the bundle formation in two-patch colloidal particle

Aggregation of protein into bundles is responsible for many neurodegenerative diseases. In this work, we show how two-patch colloidal particles self-assemble into chains and a sudden transition to bundles takes place by tuning the patch size and solvent condition. We study the kinetics of formation of chains, bundles, and networklike structures using patchy Brownian cluster dynamics. We also analyze the ways to inhibit and accelerate the formation of these bundles. We show that in the presence of inert immobile obstacles, the kinetics of formation of bundles slows down. However, in the presence of mobile aggregating particles, which exhibit interspecies hard sphere repulsion and intraspecies attraction, the kinetics of bundle formation accelerates slightly. We also show that if we introduce mobile obstacles, which exhibit interspecies attraction and intraspecies hard sphere repulsion, the kinetics of formation of bundles is inhibited. This is similar to the inhibitory effect of peptide P4 on the formation of insulin fibers. We are providing a model of mobile obstacles undergoing directional interactions to inhibit the formation of bundles.

Clinical Pharmacokinetics and Safety of ALZ-801, a Novel Prodrug of Tramiprosate in Development for the Treatment of Alzheimer's Disease

Background

ALZ-801 is an orally available, valine-conjugated prodrug of tramiprosate. Tramiprosate, the active agent, is a small-molecule β-amyloid (Aβ) anti-oligomer and aggregation inhibitor that was evaluated extensively in preclinical and clinical investigations for the treatment of Alzheimer’s disease (AD). Tramiprosate has been found to inhibit β-amyloid oligomer formation by a multi-ligand enveloping mechanism of action that stabilizes Aβ42 monomers, resulting in the inhibition of formation of oligomers and subsequent aggregation. Although promising as an AD treatment, tramiprosate exhibited two limiting deficiencies: high intersubject pharmacokinetic (PK) variability likely due to extensive gastrointestinal metabolism, and mild-to-moderate incidence of nausea and vomiting. To address these, we developed an optimized prodrug, ALZ-801, which retains the favorable efficacy attributes of tramiprosate while improving oral PK variability and gastrointestinal tolerability. In this study, we summarize the phase I bridging program to evaluate the safety, tolerability and PK for ALZ-801 after single and multiple rising dose administration in healthy volunteers.

Methods

Randomized, placebo-controlled, phase I studies in 127 healthy male and female adult and elderly volunteers included [1] a single ascending dose (SAD) study; [2] a 14-day multiple ascending dose (MAD) study; and [3] a single-dose tablet food-effect study. This program was conducted with both a loose-filled capsule and an immediate-release tablet formulation, under both fasted and fed conditions. Safety and tolerability were assessed, and plasma and urine were collected for liquid chromatography-mass spectrometry (LC-MS) determination and non-compartmental PK analysis. In addition, we defined the target dose of ALZ-801 that delivers a steady-state plasma area under the curve (AUC) exposure of tramiprosate equivalent to that studied in the tramiprosate phase III study.

Results

ALZ-801 was well tolerated and there were no severe or serious adverse events (AEs) or laboratory findings. The most common AEs were transient mild nausea and some instances of vomiting, which were not dose-related and showed development of tolerance after continued use. ALZ-801 produced dose-dependent maximum plasma concentration (C_max) and AUC exposures of tramiprosate, which were equivalent to that after oral tramiprosate, but with a substantially reduced intersubject variability and a longer elimination half-life. Administration of ALZ-801 with food markedly reduced the incidence of gastrointestinal symptoms compared with the fasted state, without affecting plasma tramiprosate exposure. An immediate-release tablet formulation of ALZ-801 displayed plasma exposure and low variability similar to the loose-filled capsule. ALZ-801 also showed excellent dose-proportionality without accumulation or decrease in plasma exposure of tramiprosate over 14 days. Based on these data, 265 mg of ALZ-801 twice daily was found to achieve a steady-state AUC exposure of tramiprosate equivalent to 150 mg twice daily of oral tramiprosate in the previous phase III trials.

Conclusions

ALZ-801, when administered in capsule and tablet forms, showed excellent oral safety and tolerability in healthy adults and elderly volunteers, with significantly improved PK characteristics over oral tramiprosate. A clinical dose of ALZ-801 (265 mg twice daily) was established that achieves the AUC exposure of 150 mg of tramiprosate twice daily, which showed positive cognitive and functional improvements in apolipoprotein E4/4 homozygous AD patients. These bridging data support the phase III development of ALZ-801in patients with AD.

Electronic supplementary material

The online version of this article (doi:10.1007/s40262-017-0608-3) contains supplementary material, which is available to authorized users.

Natural Compounds for Alzheimer's Disease Therapy: A Systematic Review of Preclinical and Clinical Studies

Alzheimer's Disease (AD) is a neurodegenerative disorder related with the increase of age and it is the main cause of dementia in the world. AD affects cognitive functions, such as memory, with an intensity that leads to several functional losses. The continuous increase of AD incidence demands for an urgent development of effective therapeutic strategies. Despite the extensive research on this disease, only a few drugs able to delay the progression of the disease are currently available. In the last years, several compounds with pharmacological activities isolated from plants, animals and microorganisms, revealed to have beneficial effects for the treatment of AD, targeting different pathological mechanisms. Thus, a wide range of natural compounds may play a relevant role in the prevention of AD and have proven to be efficient in different preclinical and clinical studies. This work aims to review the natural compounds that until this date were described as having significant benefits for this neurological disease, focusing on studies that present clinical trials.

Disclosing the Template-Induced Misfolding Mechanism of Tau Protein by Studying the Dissociation of the Boundary Chain from the Formed Tau Fibril Based on a Steered Molecular Dynamics Simulation

The level of tau aggregation into neurofibrillary tangles, including paired helical filament (PHF) and straight filament (SF), is closely associated with Alzheimer's disease. Despite the pathological importance of misfolding and aggregation of tau, the corresponding mechanism remains unclear. Therefore, to uncover the misfolding mechanism of the tau monomer upon induction of formed PHF and SF, in this study, a conventional molecular dynamics simulation combined with a steered molecular dynamics simulation was performed to study the dissociation of the boundary chain. Interestingly, our results show that the dissociation mechanisms of the boundary chain in PHF and SF are different. In PHF, the boundary chain begins to dissociate from regions β2 and β3 and ends at β8. However, in SF, it is simultaneously dissociated from β1 and β8 and ends at β5. The dissociation of the boundary chain is the reverse of template-induced misfolding of the monomer. Therefore, we can deduce the misfolding mechanism of the monomer upon induction of the template. For PHF, β8 first interacts with the template by hydrophobic interaction. Then β7, β6, β5, β4, and β1 sequentially bind to the template by electrostatic and hydrophobic interactions. After β1 binds to the template, β2 and β3 very quickly bind to the template through hydrophobic interaction. For SF, β5 of the monomer first interacts with the template by electrostatic attraction. Then β4 and β6, β3 and β7, and β2 and β8 bind to the template in turn. Finally, β1 and β8 are fully bound to the template by hydrophobic interaction. The obtained results will be vital for understanding the earlier events during misfolding and aggregation of tau.

Anti-Aβ drug candidates in clinical trials and plasmonic nanoparticle-based drug-screen for Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of neurodegenerative disorder in elderly people, and has become a social problem in aging societies globally. Amyloid-β (Aβ) aggregates (i.e., Aβ fibrils and plaques) present in the brains of AD patients are hallmarks of AD. Although various promising anti-Aβ drugs have been tested in pre-clinical and randomized controlled trials, the trial results have not yet been translated into clinical practice due to increasing time and cost of drug development. Recent investigations have addressed how the formation of Aβ aggregates is influenced by the surface of gold nanoparticles (AuNPs) to obtain a detailed understanding of the in vivo process of amyloid formation. Particularly, AuNPs catalytically provide nucleation sites to accelerate the formation of Aβ aggregates. Moreover, AuNPs have great potential as a sensing tool due to their optical property. Employing this dual function (i.e., catalytic and optical property), AuNP-based colorimetry is highlighted as a simple and innovative method for monitoring the efficacy of anti-Aβ reagents. In this review, we briefly survey important developments and designs of anti-Aβ drugs. The significance and perspectives of AuNP-based drug-screening in pharmacologic research are also discussed.

Pivotal role of carnosine in the modulation of brain cells activity: Multimodal mechanism of action and therapeutic potential in neurodegenerative disorders

Carnosine (β-alanyl-l-histidine), a dipeptide, is an endogenous antioxidant widely distributed in excitable tissues like muscles and the brain. Although discovered more than a hundred years ago and having been extensively studied in the periphery, the role of carnosine in the brain remains mysterious. Carnosinemia, a rare metabolic disorder with increased levels of carnosine in urine and low levels or absence of carnosinase in the blood, is associated with severe neurological symptoms in humans. This review deals with the role of carnosine in the brain in both physiological and pathological conditions, with a focus on preclinical evidence suggesting a high therapeutic potential of carnosine in neurodegenerative disorders. We review carnosine and carnosinemia's discoveries and the extensive research on the role and benefits of carnosine in the periphery. We then turn to carnosine's biochemistry and distribution in the brain. Using an array of recent observations as a foundation, we draw a parallel with the role of carnosine in muscles and speculate on the role of carnosine in promoting the metabolic support of neurons by glial cells. Finally, carnosine has been shown to exert a multimodal activity including inhibition of protein cross-linking and aggregation of amyloid-β and related proteins, free radical generation, nitric oxide detoxification, and an anti-inflammatory activity. It could thus play an important role in the prevention and treatment of neurodegenerative diseases such as Alzheimer's disease. We discuss the potential of carnosine in this context and speculate on new preclinical research directions.

Heparan Sulfate as a Therapeutic Target in Tauopathies: Insights From Zebrafish

Microtubule-associated protein tau (MAPT) hyperphosphorylation and aggregation, are two hallmarks of a family of neurodegenerative disorders collectively referred to as tauopathies. In many tauopathies, including Alzheimer's disease (AD), progressive supranuclear palsy (PSP) and Pick's disease, tau aggregates are found associated with highly sulfated polysaccharides known as heparan sulfates (HSs). In AD, amyloid beta (Aβ) peptide aggregates associated with HS are also characteristic of disease. Heparin, an HS analog, promotes misfolding, hyperphosphorylation and aggregation of tau protein in vitro. HS also provides cell surface receptors for attachment and uptake of tau seeds, enabling their propagation. These findings point to HS-tau interactions as potential therapeutic targets in tauopathies. The zebrafish genome contains genes paralogous to MAPT, genes orthologous to HS biosynthetic and chain modifier enzymes, and other genes implicated in AD. The nervous system in the zebrafish bears anatomical and chemical similarities to that in humans. These homologies, together with numerous technical advantages, make zebrafish a valuable model for investigating basic mechanisms in tauopathies and identifying therapeutic targets. Here, we comprehensively review current knowledge on the role of HSs in tau pathology and HS-targeting therapeutic approaches. We also discuss novel insights from zebrafish suggesting a role for HS 3-O-sulfated motifs in tau pathology and establishing HS antagonists as potential preventive agents or therapies for tauopathies.

Effects of a Dehydroevodiamine-Derivative on Synaptic Destabilization and Memory Impairment in the 5xFAD, Alzheimer's Disease Mouse Model

Carboxy-dehydroevodiamine·HCl (cx-DHED) is a derivative of DHED, which improves memory impairment. Carboxyl modification increases solubility in water, indicating that its bioavailability is higher than that of DHED. Cx-DHED is expected to have better therapeutic effects on Alzheimer's disease (AD) than DHED. In this study, we investigated the therapeutic effects of cx-DHED and the underlying mechanism in 5xFAD mice, transgenic (Tg) mouse model of AD model mice. In several behavioral tests, such as Y-maze, passive avoidance, and Morris water maze test, memory deficits improved significantly in cx-DHED-treated transgenic (Tg) mice compared with vehicle-treated Tg mice. We also found that AD-related pathologies, including amyloid plaque deposition and tau phosphorylation, were reduced after the treatment of Tg mice with cx-DHED. We determined the levels of synaptic proteins, such as GluN1, GluN2A, GluN2B, PSD-95 and Rabphilin3A, and Rab3A in the brains of mice of each group and found that GluN2A and PSD-95 were significantly increased in the brains of cx-DHED-treated Tg mice when compared with the brains of Tg-vehicle mice. These results suggest that cx-DHED has therapeutic effects on 5xFAD, AD model mice through the improvement of synaptic stabilization.

Anti-inflammatory Effects of Homotaurine in Patients With Amnestic Mild Cognitive Impairment

Alzheimer’s disease (AD) is a fatal dementing neurodegenerative disease, currently lacking an efficacious disease-modifying therapy. In the last years, there has been some interest in the use of homotaurine as a potential therapeutic compound for AD, but more work is still needed to prove its efficacy as disease modifier in dementia. Since inflammation is believed to play a key role in AD development, we sought to investigate here the in vivo homotaurine effect on inflammatory response in patients at the earliest stages of AD, i.e., suffering from amnestic mild cognitive impairment (aMCI). Thus, the present study aims to evaluate the effects of homotaurine supplementation on cytokine serum levels and memory performances in MCI patients. Neuropsychological, clinical and cytokine assessment was performed at baseline (T0) and after 1 year (T12) of homotaurine supplementation in 20 patients categorized as carriers (n = 9) or no carriers (n = 11) of the ε4 allele of the apolipoprotein E (APOE) gene, the strongest genetic risk factor for AD. The serum levels of the pro-inflammatory mediators Interleukin (IL) 1β, Tumor necrosis factor-alpha (TNFα), IL-6 and IL-18, contextually with the anti-inflammatory molecules IL-18 binding protein (IL-18BP) and Transforming growth factor-beta (TGFβ), were analyzed to explore significant differences in the inflammatory status between T0 and T12 in the two APOE variant carrier groups. No significant differences over time were observed in patients as for most cytokines, except for IL-18. Following homotaurine supplementation, patients carrying the APOEε4 allele showed a significant decrease in IL-18 (both in its total and IL-18BP unbound forms), in turn associated with improved short-term episodic memory performance as measured by the recency effect of the Rey 15-word list learning test immediate recall. Thus, homotaurine supplementation in individuals with aMCI may have a positive consequence on episodic memory loss due, at least in part, to homotaurine anti-inflammatory effects. This study strongly suggests that future research should focus on exploring the mechanisms by which homotaurine controls brain inflammation during AD progression.

The Physiological Roles of Amyloid-β Peptide Hint at New Ways to Treat Alzheimer's Disease

Amyloid-ß (Aß) is best known as the misfolded peptide that is involved in the pathogenesis of Alzheimer's disease (AD), and it is currently the primary therapeutic target in attempts to arrest the course of this disease. This notoriety has overshadowed evidence that Aß serves several important physiological functions. Aß is present throughout the lifespan, it has been found in all vertebrates examined thus far, and its molecular sequence shows a high degree of conservation. These features are typical of a factor that contributes significantly to biological fitness, and this suggestion has been supported by evidence of functions that are beneficial for the brain. The putative roles of Aß include protecting the body from infections, repairing leaks in the blood-brain barrier, promoting recovery from injury, and regulating synaptic function. Evidence for these beneficial roles comes from in vitro and in vivo studies, which have shown that the cellular production of Aß rapidly increases in response to a physiological challenge and often diminishes upon recovery. These roles are further supported by the adverse outcomes of clinical trials that have attempted to deplete Aß in order to treat AD. We suggest that anti-Aß therapies will produce fewer adverse effects if the known triggers of Aß deposition (e.g., pathogens, hypertension, and diabetes) are addressed first.

7-Deoxy-trans-dihydronarciclasine Reduces β-Amyloid and Ameliorates Memory Impairment in a Transgenic Model of Alzheimer's Disease

The critical pathological feature of Alzheimer's disease (AD) is the accumulation of β-amyloid (Aβ), the main constituent of amyloid plaques. β-amyloid precursor protein (APP) undergoes amyloidogenic cleavage by β- and γ-secretase generating Aβ at endosomes or non-amyloidogenic processing by α-secretase precluding the production of Aβ at the plasma membrane. Recently, several natural products have been widely researched on the prevention of Aβ accumulation for AD treatment. We previously reported that Lycoris chejuensis K. Tae et S. Ko (CJ), which originated from Jeju Island in Korea, improved the disrupted memory functions and reduced Aβ production in vivo. Here, we further explored the effect of its active component, 7-deoxy-trans-dihydronarciclasine (coded as E144), on Aβ generation and the underlying mechanism. Our results showed that E144 reduced the level of APP, especially its mature form, in HeLa cells overexpressing human APP with the Swedish mutation. Concomitantly, E144 decreased the levels of Aβ, sAPPβ, sAPPα, and C-terminal fragment. In addition, administration of E144 normalized the behavioral deficits in Tg2576 mice, an APP transgenic mouse model of AD. E144 also decreased the Aβ and APP levels in the cerebral cortex of Tg2576 mice. Thus, we propose that E144 could be a potential drug candidate for an anti-amyloid disease-modifying AD therapy.

Peptides as Potential Therapeutics for Alzheimer's Disease

Intracellular synthesis, folding, trafficking and degradation of proteins are controlled and integrated by proteostasis. The frequency of protein misfolding disorders in the human population, e.g., in Alzheimer's disease (AD), is increasing due to the aging population. AD treatment options are limited to symptomatic interventions that at best slow-down disease progression. The key biochemical change in AD is the excessive accumulation of per-se non-toxic and soluble amyloid peptides (Aβ(1-37/44), in the intracellular and extracellular space, that alters proteostasis and triggers Aβ modification (e.g., by reactive oxygen species (ROS)) into toxic intermediate, misfolded soluble Aβ peptides, Aβ dimers and Aβ oligomers. The toxic intermediate Aβ products aggregate into progressively less toxic and less soluble protofibrils, fibrils and senile plaques. This review focuses on peptides that inhibit toxic Aβ oligomerization, Aβ aggregation into fibrils, or stabilize Aβ peptides in non-toxic oligomers, and discusses their potential for AD treatment.

Shared pathological pathways of Alzheimer's disease with specific comorbidities: current perspectives and interventions

Alzheimer's disease (AD) belongs to one of the most multifactorial, complex and heterogeneous morbidity-leading disorders. Despite the extensive research in the field, AD pathogenesis is still at some extend obscure. Mechanisms linking AD with certain comorbidities, namely diabetes mellitus, obesity and dyslipidemia, are increasingly gaining importance, mainly because of their potential role in promoting AD development and exacerbation. Their exact cognitive impairment trajectories, however, remain to be fully elucidated. The current review aims to offer a clear and comprehensive description of the state-of-the-art approaches focused on generating in-depth knowledge regarding the overlapping pathology of AD and its concomitant ailments. Thorough understanding of associated alterations on a number of molecular, metabolic and hormonal pathways, will contribute to the further development of novel and integrated theranostics, as well as targeted interventions that may be beneficial for individuals with age-related cognitive decline.

Alzheimer's Disease Model System Using Drosophila

Alzheimer's disease (AD) is the most epidemic neuronal dysfunctions among elderly people. It is accompanied by neuronal disorders along with learning and memory defects, as well as massive neurodegeneration phenotype. The presence of intracellular neurofibrillary tangles (NFTs) and extracellular amyloid plaques, called senile plaques (SPs), and brain atrophy are typically observed in the brains of AD patients. It has been over 20 years since the discovery that small peptide, called beta-amyloid (Aβ), has pivotal role for the disease formation. Since then, a variety of drugs have been developed to cure AD; however, there is currently no effective drug for the disorder. This therapeutic void reflects lacks of ideal model system, which can evaluate the progression of AD in a short period. Recently, large numbers of AD model system have been established using Drosophila melanogaster by overproducing Aβ molecules in the brain. These systems successfully reflect some of the symptoms along with AD. In this review, we would like to point out "pros and cons" of Drosophila AD models.

Nucleic Acid-Based Theranostics for Tackling Alzheimer's Disease

Nucleic acid-based technologies have received significant interest in recent years as novel theranostic strategies for various diseases. The approval by the United States Food and Drug Administration (FDA) of Nusinersen, an antisense oligonucleotide drug, for the treatment of spinal muscular dystrophy highlights the potential of nucleic acids to treat neurological diseases, including Alzheimer's disease (AD). AD is a devastating neurodegenerative disease characterized by progressive impairment of cognitive function and behavior. It is the most common form of dementia; it affects more than 20% of people over 65 years of age and leads to death 7-15 years after diagnosis. Intervention with novel agents addressing the underlying molecular causes is critical. Here we provide a comprehensive review on recent developments in nucleic acid-based theranostic strategies to diagnose and treat AD.

Amyloid plaques beyond Aβ: a survey of the diverse modulators of amyloid aggregation

Aggregation of the amyloid-β (Aβ) peptide is strongly correlated with Alzheimer's disease (AD). Recent research has improved our understanding of the kinetics of amyloid fibril assembly and revealed new details regarding different stages in plaque formation. Presently, interest is turning toward studying this process in a holistic context, focusing on cellular components which interact with the Aβ peptide at various junctures during aggregation, from monomer to cross-β amyloid fibrils. However, even in isolation, a multitude of factors including protein purity, pH, salt content, and agitation affect Aβ fibril formation and deposition, often producing complicated and conflicting results. The failure of numerous inhibitors in clinical trials for AD suggests that a detailed examination of the complex interactions that occur during plaque formation, including binding of carbohydrates, lipids, nucleic acids, and metal ions, is important for understanding the diversity of manifestations of the disease. Unraveling how a variety of key macromolecular modulators interact with the Aβ peptide and change its aggregation properties may provide opportunities for developing therapies. Since no protein acts in isolation, the interplay of these diverse molecules may differentiate disease onset, progression, and severity, and thus are worth careful consideration.

Development of a core outcome set for disease modification trials in mild to moderate dementia: a systematic review, patient and public consultation and consensus recommendations

BACKGROUND

There is currently no disease-modifying treatment available to halt or delay the progression of the disease pathology in dementia. An agreed core set of the best-available and most appropriate outcomes for disease modification would facilitate the design of trials and ensure consistency across disease modification trials, as well as making results comparable and meta-analysable in future trials.

OBJECTIVES

To agree a set of core outcomes for disease modification trials for mild to moderate dementia with the UK dementia research community and patient and public involvement (PPI).

DATA SOURCES

We included disease modification trials with quantitative outcomes of efficacy from (1) references from related systematic reviews in workstream 1; (2) searches of the Cochrane Dementia and Cognitive Improvement Group study register, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature, EMBASE, Latin American and Caribbean Health Sciences Literature and PsycINFO on 11 December 2015, and clinical trial registries [International Standard Randomised Controlled Trial Number (ISRCTN) and clinicaltrials.gov] on 22 and 29 January 2016; and (3) hand-searches of reference lists of relevant systematic reviews from database searches.

REVIEW METHODS

The project consisted of four workstreams. (1) We obtained related core outcome sets and work from co-applicants. (2) We systematically reviewed published and ongoing disease modification trials to identify the outcomes used in different domains. We extracted outcomes used in each trial, recording how many used each outcome and with how many participants. We divided outcomes into the domains measured and searched for validation data. (3) We consulted with PPI participants about recommended outcomes. (4) We presented all the synthesised information at a conference attended by the wider body of National Institute for Health Research (NIHR) dementia researchers to reach consensus on a core set of outcomes.

RESULTS

We included 149 papers from the 22,918 papers screened, referring to 125 individual trials. Eighty-one outcomes were used across trials, including 72 scales [31 cognitive, 12 activities of daily living (ADLs), 10 global, 16 neuropsychiatric and three quality of life] and nine biological techniques. We consulted with 18 people for PPI. The conference decided that only cognition and biological markers are core measures of disease modification. Cognition should be measured by the Mini Mental State Examination (MMSE) or the Alzheimer's Disease Assessment Scale - Cognitive subscale (ADAS-Cog), and brain changes through structural magnetic resonance imaging (MRI) in a subset of participants. All other domains are important but not core. We recommend using the Neuropsychiatric Inventory for neuropsychiatric symptoms: the Disability Assessment for Dementia for ADLs, the Dementia Quality of Life Measure for quality of life and the Clinical Dementia Rating scale to measure dementia globally.

LIMITATIONS

Most of the trials included participants with Alzheimer's disease, so recommendations may not apply to other types of dementia. We did not conduct economic analyses. The PPI consultation was limited to members of the Alzheimer's Society Research Network.

CONCLUSIONS

Cognitive outcomes and biological markers form the core outcome set for future disease modification trials, measured by the MMSE or ADAS-Cog, and structural MRI in a subset of participants.

FUTURE WORK

We envisage that the core set may be superseded in the future, particularly for other types of dementia. There is a need to develop an algorithm to compare scores on the MMSE and ADAS-Cog.

STUDY REGISTRATION

The project was registered with Core Outcome Measures in Effectiveness Trials [ www.comet-initiative.org/studies/details/819?result=true (accessed 7 April 2016)]. The systematic review protocol is registered as PROSPERO CRD42015027346.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Inhibition and Degradation of Amyloid Beta (Aβ40) Fibrillation by Designed Small Peptide: A Combined Spectroscopy, Microscopy, and Cell Toxicity Study

A designed nontoxic, nonhemolytic 11-residue peptide, NF11 (NAVRWSLMRPF), not only inhibits the aggregation of amyloid beta (Aβ40) protein but also disaggregates the preformed oligomers and mature Aβ fibrils, thereby reducing associated-toxicity. NMR experiments provide evidence of NF11's ability to inhibit fibril formation, primarily through interaction with the N-terminus region as well as the central hydrophobic cluster of Aβ40. NF11 has micromolar binding affinity toward both monomeric and aggregated species for efficient clearance of toxic aggregates. From these in vitro results, the future development of a next generation peptidomimetic therapeutic agent for amyloid disease may be possible.

Sulfation of Glycosaminoglycans and Its Implications in Human Health and Disorders

Sulfation is a dynamic and complex posttranslational modification process. It can occur at various positions within the glycosaminoglycan (GAG) backbone and modulates extracellular signals such as cell-cell and cell-matrix interactions; different sulfation patterns have been identified for the same organs and cells during their development. Because of their high specificity in relation to function, GAG sulfation patterns are referred to as the sulfation code. This review explores the role of GAG sulfation in different biological processes at the cell, tissue, and organism levels. We address the connection between the sulfation patterns of GAGs and several physiological processes and discuss the misregulation of GAG sulfation and its involvement in several genetic and metabolic disorders. Finally, we present the therapeutic potential of GAGs and their synthetic mimics in the biomedical field.

Elucidating the Aβ42 Anti-Aggregation Mechanism of Action of Tramiprosate in Alzheimer's Disease: Integrating Molecular Analytical Methods, Pharmacokinetic and Clinical Data

BACKGROUND

Amyloid beta (Aβ) oligomers play a critical role in the pathogenesis of Alzheimer's disease (AD) and represent a promising target for drug development. Tramiprosate is a small-molecule Aβ anti-aggregation agent that was evaluated in phase III clinical trials for AD but did not meet the primary efficacy endpoints; however, a pre-specified subgroup analysis revealed robust, sustained, and clinically meaningful cognitive and functional effects in patients with AD homozygous for the ε4 allele of apolipoprotein E4 (APOE4/4 homozygotes), who carry an increased risk for the disease. Therefore, to build on this important efficacy attribute and to further improve its pharmaceutical properties, we have developed a prodrug of tramiprosate ALZ-801 that is in advanced stages of clinical development. To elucidate how tramiprosate works, we investigated its molecular mechanism of action (MOA) and the translation to observed clinical outcomes.

OBJECTIVE

The two main objectives of this research were to (1) elucidate and characterize the MOA of tramiprosate via an integrated application of three independent molecular methodologies and (2) present an integrated translational analysis that links the MOA, conformation of the target, stoichiometry, and pharmacokinetic dose exposure to the observed clinical outcome in APOE4/4 homozygote subjects.

METHOD

We used three molecular analytical methods-ion mobility spectrometry-mass spectrometry (IMS-MS), nuclear magnetic resonance (NMR), and molecular dynamics-to characterize the concentration-related interactions of tramiprosate versus Aβ42 monomers and the resultant conformational alterations affecting aggregation into oligomers. The molecular stoichiometry of the tramiprosate versus Aβ42 interaction was further analyzed in the context of clinical pharmacokinetic dose exposure and central nervous system Aβ42 levels (i.e., pharmacokinetic-pharmacodynamic translation in humans).

RESULTS

We observed a multi-ligand interaction of tramiprosate with monomeric Aβ42, which differs from the traditional 1:1 binding. This resulted in the stabilization of Aβ42 monomers and inhibition of oligomer formation and elongation, as demonstrated by IMS-MS and molecular dynamics. Using NMR spectroscopy and molecular dynamics, we also showed that tramiprosate bound to Lys16, Lys28, and Asp23, the key amino acid side chains of Aβ42 that are responsible for both conformational seed formation and neuronal toxicity. The projected molar excess of tramiprosate versus Aβ42 in humans using the dose effective in patients with AD aligned with the molecular stoichiometry of the interaction, providing a clear clinical translation of the MOA. A consistent alignment of these preclinical-to-clinical elements describes a unique example of translational medicine and supports the efficacy seen in symptomatic patients with AD. This unique "enveloping mechanism" of tramiprosate also provides a potential basis for tramiprosate dose selection for patients with homozygous AD at earlier stages of disease.

CONCLUSION

We have identified the molecular mechanism that may account for the observed clinical efficacy of tramiprosate in patients with APOE4/4 homozygous AD. In addition, the integrated application of the molecular methodologies (i.e., IMS-MS, NMR, and thermodynamics analysis) indicates that it is feasible to modulate and control the Aβ42 conformational dynamics landscape by a small molecule, resulting in a favorable Aβ42 conformational change that leads to a clinically relevant amyloid anti-aggregation effect and inhibition of oligomer formation. This novel enveloping MOA of tramiprosate has potential utility in the development of disease-modifying therapies for AD and other neurodegenerative diseases caused by misfolded proteins.

Current pharmacotherapy and putative disease-modifying therapy for Alzheimer's disease

Alzheimer's disease (AD) is an age-related neurodegenerative disease of the central nervous system correlated with the progressive loss of cognition and memory. β-Amyloid plaques, neurofibrillary tangles and the deficiency in cholinergic neurotransmission constitute the major hallmarks of the AD. Two major hypotheses have been implicated in the pathogenesis of AD namely the cholinergic hypothesis which ascribed the clinical features of dementia to the deficit cholinergic neurotransmission and the amyloid cascade hypothesis which emphasized on the deposition of insoluble peptides formed due to the faulty cleavage of the amyloid precursor protein. Current pharmacotherapy includes mainly the acetylcholinesterase inhibitors and N-methyl-D-aspartate receptor agonist which offer symptomatic therapy and does not address the underlying cause of the disease. The disease-modifying therapy has garnered a lot of research interest for the development of effective pharmacotherapy for AD. β and γ-Secretase constitute attractive targets that are focussed in the disease-modifying approach. Potentiation of α-secretase also seems to be a promising approach towards the development of an effective anti-Alzheimer therapy. Additionally, the ameliorative agents that prevent aggregation of amyloid peptide and also the ones that modulate inflammation and oxidative damage associated with the disease are focussed upon. Development in the area of the vaccines is in progress to combat the characteristic hallmarks of the disease. Use of cholesterol-lowering agents also is a fruitful strategy for the alleviation of the disease as a close association between the cholesterol and AD has been cited. The present review underlines the major therapeutic strategies for AD with focus on the new developments that are on their way to amend the current therapeutic scenario of the disease.

The Rationale for Insulin Therapy in Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia, with a prevalence that increases with age. By 2050, the worldwide number of patients with AD is projected to reach more than 140 million. The prominent signs of AD are progressive memory loss, accompanied by a gradual decline in cognitive function and premature death. AD is the clinical manifestation of altered proteostasis. The initiating step of altered proteostasis in most AD patients is not known. The progression of AD is accelerated by several chronic disorders, among which the contribution of diabetes to AD is well understood at the cell biology level. The pathological mechanisms of AD and diabetes interact and tend to reinforce each other, thus accelerating cognitive impairment. At present, only symptomatic interventions are available for treating AD. To optimise symptomatic treatment, a personalised therapy approach has been suggested. Intranasal insulin administration seems to open the possibility for a safe, and at least in the short term, effective symptomatic intervention that delays loss of cognition in AD patients. This review summarizes the interactions of AD and diabetes from the cell biology to the patient level and the clinical results of intranasal insulin treatment of cognitive decline in AD.