Search Results (379)

Mitochondrial dysfunction is a relevant hallmark of Alzheimer’s disease (AD), contributing to the impaired metabolic homeostasis involved in neuronal loss and cognitive decline. In this study, we target the metabolic dysfunction occurring in AD through a novel pharmacological approach involving the modulation of glutamate dehydrogenase (GDH), which converts glutamate to α-ketoglutarate and supports the tricarboxylic acid (TCA) cycle. In our experimental models (i.e., differentiated SH-SY5Y cells and primary rat cortical neurons exposed to glyceraldehyde and amyloid-beta peptide 1-42, respectively), the allosteric GDH activator 2-Aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH) increased mitochondrial ATP production, improved cellular bioenergetics, and reduced oxidative stress, ultimately promoting neuronal survival. Ionic dysfunctions in AD are linked to disrupted calcium homeostasis and organelle storing properties. In this context, GDH activation potentiated mitochondrial and endoplasmic reticulum calcium buffering capacity by enhancing store-operated calcium entry. Oxidative stress, largely driven by mitochondrial ROS overproduction, represents another major contributor to AD pathology. In our AD models BCH-mediated GDH activation reduced ROS formation and restored mitochondrial membrane potential (ΔΨ_m). Importantly, these metabolic and ionic improvements were associated with decreased accumulation of amyloid-β (Aβ_1-42) and phosphorylated tau (pTau), two key AD biomarkers. Overall, modulation of the GDH/TCA pathway represents a promising approach for restoring metabolic dysfunctions and counteracting oxidative stress and ionic dysregulation and therefore AD neurodegeneration. Full article

Alzheimer’s disease (AD) research has primarily focused on amyloid beta (Aβ) and tau protein; however, drug development targeting these two proteins has been disappointing. Therefore, there is an urgent need to explore the novel pathogenic mechanisms underlying AD. Recently, we found that expression of the K670N/M671L-mutated amyloid precursor protein (APP) in 293T cells significantly reduced membrane ferroportin (FPN) levels. Furthermore, 2-month-old APP/PS1 mice exhibited a marked decrease in membrane FPN levels, while total FPN expression and Aβ levels remained unchanged. Further studies revealed that features of ferroptosis were present in the brains of 2-month-old APP/PS1 mice, and that treatment with ferroptosis inhibitors or iron chelation significantly alleviated early pathological changes and cognitive impairment in these animals. In addition, supplementation with an APP–FPN binding peptide during the early phase ameliorated AD-related pathologies, including Aβ deposition, neuroinflammation, oxidative stress, and synapse-associated protein deficits, in APP/PS1 mice. Collectively, our findings suggest that APP mutations may contribute to early brain pathological changes and subsequent memory impairment in AD by downregulating membrane trafficking of FPN and inducing ferroptosis, thereby providing new molecular targets for drug development. Full article

Alzheimer’s disease (AD) develops as a progressive dementia condition through the step-by-step breakdown of nerve cells. Neurodegeneration in this context primarily results from metal ions, including copper, iron, zinc, and aluminum, building up in the system. The aggregation of amyloid-beta (Aβ) peptides and oxidative stress generation stem from metal ion involvement acting as defining characteristics of Alzheimer’s disease pathology. We developed a comprehensive mathematical model based on 24 coupled ordinary differential equations (ODEs) to represent the interactions between metal ions, Aβ peptides, reactive oxygen species (ROS), antioxidant defenses, and tau protein phosphorylation. The mathematical model monitors how metal ion concentrations change over time and examines their competitive binding effects, which trigger a series of reactions, resulting in oxidative stress and subsequent tau protein damage. The model uses analytical and numerical mathematical methods to expose nonlinear behaviors and threshold effects while offering mechanistic insights into the course of disease development. This model functions as a quantitative framework for assessing how therapeutic interventions that target metal dyshomeostasis and oxidative stress can potentially affect outcomes. Full article

Background/Objectives: Beta amyloid (Aβ) aggregates play a central role in the pathophysiology of Alzheimer’s disease (AD), and their detection and modulation remain major challenges in developing effective therapeutic and diagnostic strategies. Previously, gold nanoparticles with plasmonic and optical properties in the near-infrared (NIR) region and photothermal capabilities have been designed for detecting and disaggregating Aβ aggregates. However, these systems often face limitations related to biodegradability, long-term accumulation, and safety. In this work, a degradable NIR-responsive nanosystem based on small gold nanoparticles (sAuNPs), potentially excretable due to their small size, encapsulated within bovine serum albumin (BSA) and functionalized with the all-D peptide D3, was developed to inhibit Aβ aggregation. Methods: sAuNPs (~5–6 nm), functionalized with HS-PEG-NH₂, were encapsulated into BSA nanoparticles using a desolvation method and subsequently conjugated to D3, resulting in the nanosystem f-sAuNPs-BSANPs-D3. The nanosystem was characterized by UV–Vis–NIR spectroscopy, dynamic light scattering, zeta potential analysis, electron microscopy, and nanoparticle tracking analysis. The effects of the nanosystem on Aβ_1–42 aggregation were evaluated using a thioflavin T assay and electron microscopy. Additionally, the effects of f-sAuNPs-BSANPs-D3 on cell viability and its stability against trypsin digestion were assessed. Results: The nanosystem exhibited a measurable photothermal response under NIR irradiation and significantly reduced fibril formation. It did not affect the viability of SH-SY5Y neuronal cells at the tested concentrations. Trypsin incubation experiments demonstrated that the nanosystem remained stable at low enzyme concentrations mimicking plasma conditions, whereas higher enzyme concentrations induced degradation of the albumin matrix and subsequent disaggregation of sAuNPs. Conclusions: Overall, this study presents a degradable, albumin-based sAuNP nanosystem with NIR-responsive properties and potential for nanomedicine applications to inhibit Aβ aggregation in AD. Full article

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by memory decline, cognitive impairment, and behavioral changes, ultimately leading to a loss of independence and reduced quality of life. Although understanding of the molecular basis of AD has advanced, effective disease-modifying therapies remain scarce. Neuropeptides are small protein-like signaling molecules that regulate diverse physiological processes, including mood, memory, and neuronal function. Growing evidence indicates that neuropeptides are promising therapeutic candidates for AD, particularly through modulation of neuroinflammation, synaptic plasticity, and amyloid-beta (Aβ) aggregation. Preclinical AD models show that neuroprotective neuropeptides, such as neuropeptide Y (NPY), vasoactive intestinal peptide (VIP), and pituitary adenylate cyclase-activating peptide (PACAP), exert neuroprotective effects, enhance memory, and attenuate cognitive decline. This review summarizes current research on neuropeptide-based therapies for AD, detailing their molecular mechanisms, therapeutic actions, and the barriers to their clinical translation. We specifically highlight neuropeptides whose clinical potential in AD remains comparatively underrecognized, discuss strategies for optimizing their delivery and overcoming pharmacokinetic limitations, and outline future perspectives for integrating neuropeptide-based interventions into AD therapy. Full article

Objectives: Using high-performance liquid chromatography (HPLC), we developed and validated an in vitro assay for the quantitative determination of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) activity, supplementing limited current methodologies to assess the efficacy of BACE1 inhibitor compounds. A hexa-histidine tagged peptide substrate of BACE1 was used as the analyte for the determination of in vitro BACE1 activity; it was validated according to ICH guidelines. Methods: The HPLC analysis was performed on the Agilent 1290 Series Infinity II UHPLC System equipped with a Phenomenex Kinetex EVO C18 (100 × 3 mm) 5 µm column. The method was developed using a gradient programme comprising 10% aqueous acetonitrile (0.02 M TFA) to 30% aqueous acetonitrile (0.02 M TFA) for 5 min at a flow rate of 0.6 mL/min. Results: The method showed linearity over the range of 14.92 to 72 µM with ${\mathrm{r}}^2=0.9997$. The accuracy of the method in terms of mean recovery ranged between 96.62 and 98.38%. The %RSD for intra- and inter-day precision was less than 5%. Two commercial inhibitors, AZD3839 and OM99-2, were used to evaluate the performance of the method at their respective IC₅₀, resulting in inhibition of 53.46 and 50.74%, respectively. The described method addresses the void for a practical and cheap alternative to quantitatively determine the activity of BACE1 compared to current commercially available detection assays. Conclusions: We have successfully developed an HPLC method to measure the inhibitory function of two commercial inhibitors of BACE1, indicating the suitability of the method for the identification and characterisation of novel BACE1 inhibitors. Full article

Major depressive disorder (MDD) has been associated with an increased risk of cognitive decline and neurodegenerative disorders like Alzheimer’s disease (AD), prompting interest in peripheral biomarkers related to amyloid metabolism as well as neuroaxonal and astroglial injury. However, evidence regarding circulating markers in MDD remains inconsistent. In this cross-sectional study, we simultaneously assessed plasma levels of amyloid-β peptides (Aβ40 and Aβ42), neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) in MDD patients and healthy controls (HC) using ultrasensitive single-molecule array (SIMOA) technology. Associations with clinical and cognitive scales were examined. Plasma concentrations of Aβ40 and Aβ42 were significantly lower in MDD patients, whereas no group differences were observed for NfL and GFAP, after correcting for age and sex. However, both Aβ peptides were not significantly associated with depressive symptom severity, whereas the Aβ42/Aβ40 ratio was negatively associated with anhedonia. NfL and GFAP levels were primarily influenced by age. In the absence of a reduced Aβ42/Aβ40 ratio, these findings suggest that reduced plasma Aβ levels in MDD may reflect systemic or metabolic factors associated with MDD, including lifestyle or treatment-related effects. Therefore, these findings should be interpreted with caution and further examined in longitudinal studies to prevent potential confounding factors. Full article

Herpes simplex virus type 1 (HSV-1) has been proposed as an environmental risk factor for Alzheimer’s disease (AD). Viral infection of neuronal cells can reproduce hallmark pathological features of AD, including intracellular beta-amyloid (Aβ) accumulation, tau hyperphosphorylation, and lysosomal dysfunction. However, the molecular mechanisms underlying these alterations remain unclear, partly due to limitations of existing experimental models. Here, we established both two-dimensional (2D) and three-dimensional (3D) LUHMES neuronal cultures—a human mesencephalic-derived neural cell line that differentiates rapidly into mature neurons—to investigate HSV-1-induced AD-associated markers. Our results demonstrate that HSV-1 infection induces key features of AD, including intracellular accumulation of Aβ peptides and hyperphosphorylation of tau protein. Moreover, we observed disruptions in the autophagy–lysosome pathway, characterized by increased LC3-II levels, reduced cathepsin activity, and impaired lysosomal burden. Notably, these AD-like alterations were reproduced in 3D LUHMES neuronal aggregates, confirming their susceptibility to productive HSV-1 infection. Collectively, these findings indicate that HSV-1 not only triggers AD-like neuropathological markers but also disrupts cellular clearance mechanisms that may contribute to neuronal dysfunction and degeneration. This study validates the 3D LUHMES system as a useful human neuronal model to study virus-induced neurodegeneration and its mechanistic links to AD pathology. Full article

Tetraclinis articulata volatile phytocomplexes contain numerous bioactive terpenoids with neuroprotective potential; however, their efficacy in Alzheimer’s disease (AD)-related neuropsychiatric symptoms remain insufficiently explored. This study investigated the therapeutic effects of a Tetraclinis articulata-derived volatile phytocomplex (TLO) administered via inhalation at 1% and 3% concentrations for 21 consecutive days in a rat model of AD induced by intracerebroventricular injection of amyloid-beta 1–42 peptide (Aβ_1–42). Behavioral assessment revealed that both 1% and 3% TLO significantly ameliorated anxiety- and depression-like behaviors, with effects comparable to diazepam (3 mg/kg, i.p.) and imipramine (20 mg/kg, i.p.), respectively. These behavioral improvements coincided with a partial restoration of brain-derived neurotrophic factor (BDNF) expression in the amygdala, whereas activity-regulated cytoskeleton-associated protein (ARC) levels remained unaffected. TLO also attenuated oxidative stress by reducing malondialdehyde (MDA) accumulation and enhancing superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities, thereby contributing to the recovery of redox homeostasis. Furthermore, TLO provided significant protection against Aβ_1–42-induced apoptotic DNA fragmentation, although it produced only minimal reductions in IL-1β expression, indicating limited anti-inflammatory effects. Collectively, these findings demonstrate that inhaled TLO, particularly at 1% and 3%, alleviates Aβ_1–42-induced neuropsychiatric disturbances through antioxidant, anti-apoptotic, and BDNF-associated mechanisms, supporting its potential as an adjuvant phytotherapeutic strategy for managing behavioral symptoms in AD. Full article

While genetics implicate a central role for dysregulated innate immunity in Alzheimer’s disease (AD), the contributions of peripheral myeloid cells, such as monocytes, have been largely overlooked in favor of microglia. Here, we investigate whether AD-associated loci, specifically rs3865444 in the CD33 locus and rs1057233 in the SPI1 locus, converge on shared functional pathways in monocytes in the context of amyloid-beta peptide 1-42 (Aβ1-42) as an immune stimulus. To do so, we isolated monocytes from peripheral blood mononuclear cells (PBMCs) from healthy individuals and exposed them to aggregated Aβ1-42. In this study, we identify functional convergence of the CD33 and SPI1 AD risk variants in the context of aggregated Aβ, both resulting in reduced phagocytosis and loss of surface TREM2 expression, demonstrating an interaction between genetics and environment to reduce myeloid cell fitness. These findings highlight that peripheral monocytes, like brain-resident microglia, are genetically and functionally linked to AD risk, underscoring their importance as accessible immune cells that contribute to disease susceptibility and progression. Full article

Alzheimer’s Disease (AD) is one of the most commonly seen neurodegenerative disorders, where early detection of its biomarkers is crucial for effective management. Conventional diagnostic methods are often expensive, time-consuming, and highly complex, which highlights an urgent need for point-of-care biosensing technology. In this work, we developed assays on three-dimensional (3D) graphene foam electrodes by functionalising them with a 1-Pyrenebutyric acid N-hydroxysuccinimide ester (Pyr-NHS) to enable effective antibody immobilisation for the detection of amyloid beta peptides (Aβ42 and Aβ40), key biomarkers for AD. Pyr-NHS linkers were used for stable functionalisation, followed by binding with Aβ42 and Aβ40 antibodies, and then bovine serum albumin (BSA) was employed as a blocking agent to minimise non-specific bindings on the electrode surface. Differential Pulse Voltammetry (DPV) measurements showed satisfactory stability over 12 days (RDS upper limit was <10%) and highly sensitive and specific detection of Aβ42 and Aβ40, with insignificant interference of tau217 protein. The biosensor exhibited a low limit of detection (LOD) with 252 aM for Aβ42 and 395 aM for Aβ40, covering 0.125 fM–1 nM and 0.125 fM–100 pM linear ranges, respectively. Further validation was conducted on spiked-diluted human plasma. This excellent analytical performance was attributed to the stable Pyr-NHS functionalisation, the 3D graphene foam enabling superior conductivity and a larger surface area on the working electrode, and the optimisation of antibody concentration for immobilisation. These promising results suggest that 3D graphene foam-based biosensors have considerable potential for early detection of AD biomarkers and developing cost-effective, portable, and reliable point-of-care devices. Full article

Abnormal accumulation of amyloid-beta (Aβ) peptides in the brain is a hallmark of Alzheimer’s disease (AD). Importantly, the peripheral blood cells are also exposed to the effects of pathological peptides that accumulate in AD. Herein, the interaction of Aβ42 oligomers (Aβ42) with human red blood cells (RBCs) and erythrocyte ghosts as in vitro models for AD is studied combining fluorescence spectroscopy, fluorescence microscopy, and electrokinetics. The binding of Aβ42 to RBCs was evidenced by the use of a fluorescent-labeled peptide. The membrane lipid order increased with the increase in both the Aβ42 concentration and the incubation time, creating a lipid–protein microenvironment characterized by higher molecular order and reduced heterogeneity in RBC membranes compared to control conditions. Notably, the increase in lipid order was less pronounced in erythrocyte ghosts than in intact RBCs. Furthermore, the ζ-potential measurements revealed Aβ42 induced alteration of the surface potential of RBCs in a concentration- and time-dependent manner, with freshly isolated RBCs exhibiting a highly negative potential that became increasingly negative at higher Aβ42 concentrations. These findings suggest that Aβ42 not only impacts neuronal function but also significantly alters the physical properties of RBCs that might compromise their function, potentially contributing to the systemic effects observed in AD. Full article

Alzheimer’s disease (AD) has been studied extensively and is characterized by plaques deposited throughout the brain. Plaques are made of beta-amyloid (Aβ) peptides which have undergone fibrillogenesis to form insoluble Aβ fibrils (fAβ) that are neurotoxic. Receptor for Advanced Glycation End end products (RAGE), toll-like receptors (TLRs) 2 and 4, and co-receptor CD14 recognize negatively charged binding regions on fAβ to activate microglia and release proinflammatory cytokines. In this study, we used two experimentally resolved fAβ structures (type I and II) isolated from AD brain tissue to elucidate binding patterns of fAβ with RAGE, TLR2, TLR4, and CD14 and investigated whether binding was affected by fibril structure or system pH. Receptors TLR2 and RAGE formed tight complexes with both type I and II fibrils, while TLR4 showed selectivity for type I. CD14 binding was less tight and selective for type II. Binding was pH dependent for CD14, TLR4, and RAGE but not TLR2. We explored the effects of familial mutations on fibril structure to determine whether mutants of type I or II structures are feasible. Finally, we investigated whether mutations affected binding interactions of fAβ with proteins. The Arctic (Glu22Gly), Dutch (Glu22Gln), and Iowa (Asp23Asn) mutations showed similar effects on binding affinity. Italian (Glu22Lys) mutations abrogated binding, whereas type I and II fibrils with Flemish (Ala21Gly) mutations were not shown to be feasible. Results highlight the adaptability of immune receptors in recognizing damaging molecules, with fibril structure and pH being the main recognition determinants predicated on disease progression. In silico mutations showed that aggregates similar to type I and II structures were plausible for some familial mutations. Full article

Alzheimer’s disease (AD) is a multifactorial neurodegenerative disorder characterized by extracellular accumulation of amyloid-beta (Aβ) peptide, intracellular neurofibrillary tangles (NFTs), severe neuronal loss, and a marked decline in cholinergic function. Due to the limited efficacy of currently available therapies, the search for new chemical scaffolds able to target multiple pathological mechanisms remains an urgent priority. Among the most promising strategies are heterocyclic frameworks that can simultaneously interact with cholinesterase (ChE) enzymes and inhibit amyloid-β (Aβ) aggregation while also exhibiting antioxidant activity. In this context, we report a series of quinazoline derivatives synthesized via a sequential, one-pot multicomponent reaction, in good yields. Several of these compounds demonstrated notable antioxidant properties, as well as inhibitory effects on ChE activity and Aβ_1-42 self-aggregation, highlighting their potential as multifunctional agents for the treatment of neurodegenerative disorders. Notably, 2-ethyl-4-(3,4-Dimethoxyphenyl)aminoquinazoline (3h) demonstrated the most balanced biological profile among the tested compounds, exhibiting an ORAC value of 5.73 TE, an acetylcholinesterase (AChE) inhibition IC₅₀ = 6.67 μM, and 36.68% inhibition of Aβ_1–42 aggregation, closely approaching the activity of curcumin. These findings highlight compound 3h as a promising quinazoline-based hit for the development of multifunctional agents targeting AD. Full article

Alzheimer’s disease (AD) is the most common form of dementia, characterized by progressive memory loss and cognitive decline. Its key pathological hallmarks include extracellular amyloid plaques composed of amyloid beta (Aβ) peptides and intracellular neurofibrillary tangles formed by hyperphosphorylated tau protein. Although numerous studies have investigated the complex pathology of AD, its underlying mechanisms remain incompletely understood. The amyloid cascade hypothesis continues to be the leading model of AD pathogenesis. It suggests that Aβ aggregation is the initial trigger of neurotoxicity, setting off a cascade of pathological events including inflammation, oxidative stress, tau hyperphosphorylation, synaptic dysfunction, and, ultimately, dementia. Molecular dynamics (MD) is a powerful tool in structure-based drug design (SBDD). By simulating biomolecular motions at the atomic level, MD provides unique insights into molecular properties, functions, and inhibition mechanisms—insights often inaccessible through other experimental or computational techniques. When integrated with experimental data, MD further deepens our understanding of molecular interactions and biological processes. Natural compounds, known for their pleiotropic pharmacological activities, favorable safety profiles, and general tolerability (despite occasional side effects), are increasingly explored for their potential in both the treatment and prevention of various diseases, including AD. In this review, we summarize current findings from MD simulations of natural compounds with anti-amyloidogenic potential. This work builds upon our previous publication, which focused on endogenous compounds and repurposed drugs. The review is structured as follows: an overview of the amyloid cascade hypothesis; a discussion of Aβ oligomeric structures and their stabilizing interactions; a section on molecular dynamics, including its challenges and future directions; and a comprehensive analysis of the inhibitory mechanisms of natural compounds, categorized by their shared structural features. Full article