Amyloid-β Toxicity Research Articles

Break and accelerator-The mechanics of Tau (and amyloid) toxicity.

Aggregates of the microtubule-associated protein Tau define more than a dozen primary tauopathies, and together with amyloid-β, the secondary tauopathy Alzheimer's disease (AD). Historically, Tau has been viewed as executor of amyloid-β toxicity, with the two molecules working together as "trigger and bullet." Given the two protein's opposing roles in protein translation, we wish to introduce another metaphor, borrowing from the mechanics of a car, with amyloid-β boosting Tau translation, whereas Tau puts a break on global translation. The underlying studies entail an alternative hypothesis regarding Tau's subcellular accumulation in AD, namely its de novo synthesis in the somatodendritic domain rather than the relocalization from the axon upon dissociation from microtubules. We contest that it may be worth (given Tau's 50th birthday) to revisit some entrenched dogmas about Tau's pathophysiology.

T1AM/TAAR1 System Reduces Inflammatory Response and β-Amyloid Toxicity in Human Microglial HMC3 Cell Line.

Microglial dysfunction is one of the hallmarks and leading causes of common neurodegenerative diseases (NDDs), including Alzheimer's disease (AD) and Parkinson's disease (PD). All these pathologies are characterized by aberrant aggregation of disease-causing proteins in the brain, which can directly activate microglia, trigger microglia-mediated neuroinflammation, and increase oxidative stress. Inhibition of glial activation may represent a therapeutic target to alleviate neurodegeneration. Recently, 3-iodothyronamine (T1AM), an endogenous derivative of thyroid hormone (TH) able to interact directly with a specific GPCR known as trace amine-associated receptor 1 (TAAR1), gained interest for its ability to promote neuroprotection in several models. Nevertheless, T1AM's effects on microglial disfunction remain still elusive. In the present work we investigated whether T1AM could inhibit the inflammatory response of human HMC3 microglial cells to LPS/TNFα or β-amyloid peptide 25-35 (Aβ25-35) stimuli. The results of ELISA and qPCR assays revealed that T1AM was able to reduce microglia-mediated inflammatory response by inhibiting the release of proinflammatory factors, including IL-6, TNFα, NF-kB, MCP1, and MIP1, while promoting the release of anti-inflammatory mediators, such as IL-10. Notably, T1AM anti-inflammatory action in HMC3 cells turned out to be a TAAR1-mediated response, further increasing the relevance of the T1AM/TAAR1 system in the management of NDDs.

Ethyl acetate extract of Gastrodiaelata protects Caenorhabditis elegans from oxidative stress and amyloid β peptide toxicity.

Gastrodia elata Blume is a traditional Chinese medicine with a long history, which has numerous pharmacological activities, such as anti-inflammation, anti-oxidation and protection of nerves. The present study investigated the regulatory effect of ethyl acetate extract of Gastrodia elata (EEGE) on the β-amyloid (Aβ) toxicity of Caenorhabditis elegans (C. elegans). First, the main components of EEGE were analyzed using high-performance liquid chromatography, and the total phenols, total flavonoids and total antioxidant capacity of EEGE were determined. Next, the regulation effect of EEGE on Aβ-induced toxicity of C. elegans was evaluated through experiments on nematode paralysis, lifespan, oxidative and heat stress, locomotor ability, reproductive ability, reactive oxygen species (ROS) level, Aβ aggregation test, malondialdehyde (MDA) level, catalase (CAT) activity and superoxide dismutase (SOD) activity. Finally, the mechanism of EEGE was elucidated using RNA sequencing (RNA-Seq) and the expression levels of related genes were verified using quantitative PCR. The present study revealed that the main components of EEGE included phosphorylated (p)-hydroxybenzyl alcohol, p-hydroxybenzaldehyde and 4,4'-dihydroxydiphenylmethane, possessing strong in vitro free radical scavenging and reducing abilities. In addition, after the intervention of EEGE, the paralysis of nematodes could be delayed, the survival time of the nematodes was prolonged, the survival rate of the nematodes under stress (high temperature and oxidation) conditions was improved, the activity capacity and reproductive capacity of the nematodes were improved, the activities of SOD and CAT were improved and the levels of ROS and MDA were reduced. Notably, EEGE directly inhibited Aβ plaque aggregation in nematodes. RNA-Seq analysis showed that EEGE regulated metabolism and longevity-related genes, and these genes were regulated by the insulin/IGF-1 signaling (IIS) pathway. Therefore, the present study hypothesized that the regulatory mechanism of EEGE was significantly related to the IIS pathway. The present research results demonstrated that the protective effect of EEGE on transgenic C. elegans was to reduce Aβ protein aggregation, improve the in vivo antioxidant level, effectively remove free radicals and to regulate the expression of genes related to IIS pathway, thereby reducing Aβ-induced toxicity and delaying nematode paralysis.

Potential Anti-Alzheimer Properties of Mogrosides in Vitamin B12-Deficient Caenorhabditis elegans

Vitamin B12 deficiency can lead to oxidative stress, which is known to be involved in neurodegenerative diseases such as Alzheimer's disease (AD). Mogrosides are plant-derived triterpene glycosides that exhibit anti-inflammatory and antioxidant activity in animal cell lines and mouse models. Since amyloid-β toxicity is known to cause oxidative stress and damage to brain cells, we hypothesized that mogrosides may have a protective effect against AD. In this study, we investigated the potential anti-AD effect of mogrosides in vitamin B12-deficient wild-type N2 and in transgenic CL2355 Caenorhabditis elegans expressing amyloid-β peptide. Our data indicated that mogrosides have a beneficial effect on the lifespan and egg-laying rate of N2 and vitamin B12-deficient N2 worms. Additionally, the results revealed that mogrosides can effectively delay the paralysis of CL2355 worms as determined by serotonin sensitivity assay. Our analysis showed that mogrosides increase the expression of oxidative protective genes in N2 worms fed with vitamin B12-deficient OP50 bacterium. We conclude that mogrosides may exert preventative rather than curative effects that counteract the detrimental vitamin B12-deficient environment in N2 and CL2355 C. elegans by modulating oxidation-related gene expression.

Hyperoside alleviates toxicity of β-amyloid via endoplasmic reticulum-mitochondrial calcium signal transduction cascade in APP/PS1 double transgenic Alzheimer's disease mice

Alzheimer's disease is a neurodegenerative disorder characterized by a decline in cognitive function. The β-amyloid (Aβ) hypothesis suggests that Aβ peptides can spontaneously aggregate into β-fragment-containing oligomers and protofibrils, and this activation of the amyloid pathway alters Ca2+ signaling in neurons, leading to neurotoxicity and thus apoptosis of neuronal cells. In our study, a blood-brain barrier crossing flavonol glycoside hyperoside was identified with anti-Aβ aggregation, BACE inhibitory, and neuroprotective effect in cellular or APP/PSEN1 double transgenic Alzheimer's disease mice model. While our pharmacokinetic data confirmed that intranasal administration of hyperoside resulted in a higher bio-availability in mice brain, further in vivo studies revealed that it improved motor deficit, spatial memory and learning ability of APP/PSEN1 mice with reducing level of Aβ plaques and GFAP in the cortex and hippocampus. Bioinformatics, computational docking and in vitro assay results suggested that hyperoside bind to Aβ and interacted with ryanodine receptors, then regulated cellular apoptosis via endoplasmic reticulum-mitochondrial calcium (Ca2+) signaling pathway. Consistently, it was confirmed that hyperoside increased Bcl2, decreased Bax and cyto-c protein levels, and ameliorated neuronal cell death in both in vitro and in vivo model. By regulating Aβ-induced cell death via regulation on Ca2+ signaling cascade and mitochondrial membrane potential, our study suggested that hyperoside may work as a potential therapeutic agent or preventive remedy for Alzheimer's disease.

Cobalt nanoparticles induce mitochondrial damage and β-amyloid toxicity via the generation of reactive oxygen species

Exposure to cobalt nanoparticles (CoNPs) has been associated with neurodegenerative disorders, while the mitochondrial-associated mechanisms that mediate their neurotoxicity have yet to be fully characterized. In this study, we reported that CoNPs exposure reduced the survival and lifespan in the nematodes, Caenorhabditis elegans (C. elegans). Moreover, exposure to CoNPs aggravated the induction of paralysis and the aggregation of β-amyloid (Aβ). These effects were accompanied by reactive oxygen species (ROS) overproduction, ATP reduction as well as mitochondrial fragmentation. Dynamin-related protein 1 (drp-1) activation and ensuing mitochondrial fragmentation have been shown to be associated with CoNPs-reduced survival. In order to address the role of mitochondrial damage and ROS production in CoNPs-induced Aβ toxicity, the mitochondrial reactive oxygen species scavenger mitoquinone (Mito Q) was used. Our results showed that Mito Q pretreatment alleviated CoNPs-induced ROS generation, rescuing mitochondrial dysfunction, thereby lessening the CoNPs-induced Aβ toxicity. Taken together, we show for the first time, that increasing of ROS and the upregulation of drp-1 lead to CoNPs-induced Aβ toxicity. Our novel findings provide in vivo evidence for the mechanisms of environmental toxicant-induced Aβ toxicity, and can afford new modalities for the prevention and treatment of CoNPs-induced neurodegeneration.

Neuroprotective Effects of a Multi-Herbal Extract on Axonal and Synaptic Disruption in Vitro and Cognitive Impairment in Vivo.

Alzheimer's disease (AD) is a multifactorial disorder characterized by cognitive decline. Current available therapeutics for AD have limited clinical benefit. Therefore, preventive therapies for interrupting the development of AD are critically needed. Molecules targeting multifunction to interact with various pathlogical components have been considered to improve the therapeutic efficiency of AD. In particular, herbal medicines with multiplicity of actions produce cognitive benefits on AD. Bugu-M is a multi-herbal extract composed of Ganoderma lucidum (Antler form), Nelumbo nucifera Gaertn., Ziziphus jujuba Mill., and Dimocarpus longan, with the ability of its various components to confer resilience to cognitive deficits. To evaluate the potential of Bugu-M on amyloid-β (Aβ) toxicity and its in vitro mechanisms and on in vivo cognitive function. We illustrated the effect of Bugu-M on Aβ25-35-evoked toxicity as well as its possible mechanisms to diminish the pathogenesis of AD in rat cortical neurons. For cognitive function studies, 2-month-old female 3×Tg-AD mice were administered 400 mg/kg Bugu-M for 30 days. Behavioral tests were performed to assess the efficacy of Bugu-M on cognitive impairment. In primary cortical neuronal cultures, Bugu-M mitigated Aβ-evoked toxicity by reducing cytoskeletal aberrations and axonal disruption, restoring presynaptic and postsynaptic protein expression, suppressing mitochondrial damage and apoptotic signaling, and reserving neurogenic and neurotrophic factors. Importantly, 30-day administration of Bugu-M effectively prevented development of cognitive impairment in 3-month-old female 3×Tg-AD mice. Bugu-M might be beneficial in delaying the progression of AD, and thus warrants consideration for its preventive potential for AD.

Gut Microbiota is an Impact Factor based on the Brain-Gut Axis to Alzheimer's Disease: A Systematic Review.

Alzheimer's disease (AD) is a degenerative disease of the central nervous system. The pathogenesis of AD has been explained using cholinergic, β-amyloid toxicity, tau protein hyperphosphorylation, and oxidative stress theories. However, an effective treatment method has not been developed. In recent years, with the discovery of the brain-gut axis (BGA) and breakthroughs made in Parkinson's disease, depression, autism, and other diseases, BGA has become a hotspot in AD research. Several studies have shown that gut microbiota can affect the brain and behavior of patients with AD, especially their cognitive function. Animal models, fecal microbiota transplantation, and probiotic intervention also provide evidence regarding the correlation between gut microbiota and AD. This article discusses the relationship and related mechanisms between gut microbiota and AD based on BGA to provide possible strategies for preventing or alleviating AD symptoms by regulating gut microbiota.

Bacopa monnieri protects neuronal cell line and Caenorhabditis elegans models of Alzheimer’s disease through sigma-1 receptor antagonist sensitive and antioxidant pathways

BACKGROUND: Due to better health care and improved nutritional status of the world’s population, many people live into old age. This has resulted in more diseases related to aging, such as neurodegenerative diseases. Bacopa monnieri (BM) is a medicinal herb found in Southeast Asia and is a popular memory-enhancing supplement. OBJECTIVE: This study aimed to investigate how BM may provide protection in neurodegenerative disease, and whether the sigma-1 receptor is involved. METHODS: PC-12 cells were differentiated with the addition of nerve growth factor. The potentiation by BM of PC-12 neurite growth was measured by counting the number of differentiated cells and by measuring their length. Differentiated PC-12 cells were also subjected to amyloid-β (Aβ) toxicity in the presence and absence of BM. The cell survival (MTT and cell counting) and neurite lengths were then measured as indicators of cellular health. Total protein was extracted from control and treated cells and expression of various signalling pathway molecules was assessed via western blotting. We also assessed the effects of BM on the lifespans of various mutant strains plus wild-type C. elegans. RESULTS: We show that BM can protect against Aβ toxicity in PC-12 cells. Furthermore, BM can potentiate neurite outgrowth in PC-12, in a sigma-1 receptor antagonist sensitive fashion, and Neuro2A cell lines. BM induced a reduction in pAKT expression and upregulated BDNF expression in PC-12 cells. BM was also able to increase the lifespan and health-span of Aβ expressing C. elegans mutants via the DAF-16 mediated pathway. BM reduced oxidative stress in wild-type C. elegans exposed to UV-A with pre-exposure and post-exposure treatments. CONCLUSIONS: This all further identifies BM as a potential agent to treat neurodegenerative diseases, by modulating different pathways.

Ginsenoside Rd protects transgenic Caenorhabditis elegans from β-amyloid toxicity by activating oxidative resistant.

Alzheimer's disease (AD) is a serious public health issue but few drugs are currently available for the disease, and these only target the symptoms. It is well established that oxidative stress plays a crucial role in AD, and there is compelling evidence linking oxidative stress to β-amyloid (Aβ). An exciting source of potential new AD therapeutic medication possibilities is medicinal plants. Ginsenoside Rd (GS-Rd) is one of the main bioactive substances in ginseng extracts. In our study, we used a network pharmacology analysis to identify overlapping GS-Rd (therapeutic) and AD (disease)-relevant protein targets, gene ontology (GO) and bio-process annotation, and the KEGG pathway analysis data predicted that GS-Rd impacts multiple targets and pathways, such as the MAPK signal pathway and the JAT-STAT3 signaling pathway. We then assessed the role of GS-Rd in C. elegans and found that GS-Rd prolongs lifespan, improves resistance to heat stress, delays physical paralysis and increases oxidative stress responses. Overall, these results suggest that GS-Rd protects against the toxicity of Aβ. The RNA-seq analysis revealed that GS-Rd achieves its effects by regulating gene expressions like daf-16 and skn-1, as well as by participating in many AD-related pathways like the MAPK signaling pathway. In addition, in CL4176 worms, GS-Rd decreased reactive oxygen species (ROS) levels and increased SOD activity. Additional research with transgenic worms showed that GS-Rd aided in the movement of DAF-16 from the cytoplasm to the nucleus. Taken together, the results indicate that GS-Rd significantly reduces Aβ aggregation by targeting the MAPK signal pathway, induces nuclear translocation of DAF-16 to activate downstream signaling pathways and increases resistance to oxidative stress in C. elegans to protect against Aβ-induced toxicity.

Multifunctional Architectures of Cyclic Dipeptide Copolymers and Composites, and Modulation of Multifaceted Amyloid-β Toxicity.

Alzheimer's disease (AD) is a major neurodegenerative disorder primarily characterized by the β-amyloid (Aβ42) misfolding and aggregation-associated multifaceted amyloid toxicity encompassing oxidative stress, neuronal death, and severe cognitive impairment. Modulation of Aβ42 aggregation via various structurally anisotropic macromolecular systems is considered effective in protecting neuronal cells. In this regard, we have developed a cyclic dipeptide (CDP)-based copolymer (CP) and explored its material and biomedical properties. Owing to the structural versatility, CDP-CP forms solvent-dependent anisotropic architectures ranging from dense fibers and mesosheets to vesicles, which are shown to interact with dyes and nanoparticles and mimic synthetic protocells, providing a conceptually new approach to achieve advanced functional materials with the hierarchical organization. CP upon interaction with gold nanoparticles (GNP) and polyoxometalate (POM) generated faceted architectures (CP-GNP) and the nanocomposite (CP-POM), respectively. CP-GNP and CP-POM have shown remarkable ability to inhibit Aβ42 aggregation, dissolve the preformed aggregates, and scavenge reactive oxygen species (ROS) to ameliorate multifaceted amyloid toxicity. In cellulo studies show that CP-GNP and CP-POM protect neuronal cells from Aβ42-induced toxicity and reduce lipopolysaccharide (LPS)-activated neuroinflammation at sub-micromolar concentration. To our knowledge, this is the first report on the hierarchical organization of CDP-CP into 1D-to-2D architectures and their organic-inorganic hybrid nanocomposites to combat the multifaceted amyloid toxicity.

Identifying the Template for Oligomer to Fibril Conversion for Amyloid-β (1-42) Oligomers using Hamiltonian Replica Exchange Molecular Dynamics.

The toxicity of amyloid-β (Aβ) oligomers has been known to be higher compared to mature fibrils. Yet the presence of plaques in Alzheimer's disease patients indicates the significance of oligomer to fibril conversion for Aβ aggregates. In this study, we investigate Aβ13-42 oligomers having two to five peptide chains using extensive all-atom molecular dynamics simulations to identify the on- or off-pathway intermediates in fibril formation pathway. Hamiltonian replica exchange method through solute tempering (REST2) has been employed to explore the different structures attained by these aggregates. Using intra-chain and inter-chain contacts as reaction coordinates, we obtain the free energy surface for the Aβ13-42 oligomers. Consequently, their stable conformations and structural features have been identified. The found conformations belonging to most probable structures possess both parallel and anti-parallel β-sheets, characteristic of on- and off-pathway intermediates, respectively. Further, we have measured the tendency to form fibril like interactions among the β-sheet forming residues. Our analysis finds that residues 30-36 possess higher tendency to form fibril like contacts among all the residues. While we find stronger interaction among residues 30-36, these amino acids are also found to be more shielded from water compared to others. With previous experimental studies finding these residues to be more crucial for the stability of Aβ42 oligomers, we propose that interactions within this patch could trigger seed formation that leads to conversion of on-pathway oligomers into disease relevant fibrils.

Native PLGA nanoparticles regulate APP metabolism and protect neurons against β-amyloid toxicity: Potential significance in Alzheimer's disease pathology

Biodegradable poly(lactic-co-glycolic acid)(PLGA) nanoparticles have been used extensively in delivering drugs to target tissues due to their excellent biocompatibility. Evidence suggests that PLGA-conjugated drugs/agents can attenuate pathology in cellular/animal models of Alzheimer's disease (AD), which is initiated by increased level/aggregation of amyloid β (Aβ) peptide generated from amyloid precursor protein (APP). The beneficial effects were attributed to conjugated-drugs rather than to PLGA nanoparticles. Interestingly, we recently reported that PLGA without any drug/agent (native PLGA) can suppress Aβ aggregation/toxicity. However, very little is known about the internalization, subcellular localization or effects of PLGA in neurons. In this study, using primary mouse cortical neurons, we first showed that native PLGA is internalized by an energy-mediated clathrin-dependent/-independent pathway and is localized in endosomal-lysosomal-autophagic vesicles. By attenuating internalization, PLGA can protect neurons against Aβ-mediated toxicity. Additionally, PLGA treatment altered expression profiles of certain AD-associated genes and decreased the levels of APP, its cleaved products α-/β-CTFs and Aβ peptides in mouse as well as iPSC-derived neurons from control and AD patients. Collectively, these results suggest that native PLGA not only protects neurons against Aβ-induced toxicity but also influences the expression of AD-related genes/proteins – highlighting PLGA's implication in normal and AD-related pathology.

Binding Models of Aβ42 Peptide with Membranes Explored by Molecular Simulations.

One of the factors contributing to the toxicity of amyloid-β (Aβ) peptides is the destruction of membrane integrity through Aβ peptide-membrane interactions. The binding of Aβ peptides to membranes has been studied by experiments and theoretical simulations extensively. The exact binding mechanism, however, still remains elusive. In the present study, the molecular basis of the peptide-bilayer binding mechanism of the full-length Aβ42 monomer with POPC/POPS/CHOL bilayers is investigated by all-atom (AA) simulations. Three main binding models in coil, bend, and turn structures are obtained. Model 1 of the three models with the central hydrophobic core (CHC) buried inside the membrane is the dominant binding model. The structural features of the peptide, the peptide-bilayer interacting regions, the intrapeptide interactions, and peptide-water interactions are studied. The binding of the Aβ42 monomer to the POPC/POPS/CHOL bilayer is also explored by coarse-grained (CG) simulations as a complement. Both the AA and CG simulations show that residues in CHC prefer forming interactions with the bilayer, indicating the crucial role of CHC in peptide-bilayer binding. Our results can provide new insights for the investigation of the peptide-bilayer binding mechanism of the Aβ peptide.

Intravenous treatment with a molecular chaperone designed against β-amyloid toxicity improves Alzheimer’s disease pathology in mouse models

Attempts to treat Alzheimer's disease with immunotherapy against the β-amyloid (Aβ) peptide or with enzyme inhibitors to reduce Aβ production have not yet resulted in effective treatment, suggesting that alternative strategies may be useful. Here we explore the possibility of targeting the toxicity associated with Aβ aggregation by using the recombinant human (rh) Bri2 BRICHOS chaperone domain, mutated to act selectively against Aβ42 oligomer generation and neurotoxicity invitro. We find that treatment of Aβ precursor protein (App) knockin mice with repeated intravenous injections of rh Bri2 BRICHOS R221E, from an age close to the start of development of Alzheimer's disease-like pathology, improves recognition and working memory, as assessed using novel object recognition and Y maze tests, and reduces Aβ plaque deposition and activation of astrocytes and microglia. When treatment was started about 4months after Alzheimer's disease-like pathology was already established, memory improvement was not detected, but Aβ plaque deposition and gliosis were reduced, and substantially reduced astrocyte accumulation in the vicinity of Aβ plaques was observed. The degrees of treatment effects observed in the App knockin mouse models apparently correlate with the amounts of Bri2 BRICHOS detected in brain sections after the end of the treatment period.

Scorpion Venom Heat-Resistant Synthesized Peptide Increases Stress Resistance and Extends the Lifespan of Caenorhabditis elegans via the Insulin/IGF-1-Like Signal Pathway.

Improving healthy life expectancy by targeting aging-related pathological changes has been the spotlight of geroscience. Scorpions have been used in traditional medicine in Asia and Africa for a long time. We have isolated heat-resistant peptides from scorpion venom of Buthusmartensii Karsch (SVHRP) and found that SVHRP can attenuate microglia activation and protect Caenorhabditis elegans (C. elegans) against β-amyloid toxicity. Based on the amino acid sequence of these peptides, scorpion venom heat–resistant synthesized peptide (SVHRSP) was prepared using polypeptide synthesis technology. In the present study, we used C. elegans as a model organism to assess the longevity-related effects and underlying molecular mechanisms of SVHRSP in vivo. The results showed that SVHRSP could prolong the lifespan of worms and significantly improve the age-related physiological functions of worms. SVHRSP increases the survival rate of larvae under oxidative and heat stress and decreases the level of reactive oxygen species and fat accumulation in vivo. Using gene-specific mutation of C. elegans, we found that SVHRSP-mediated prolongation of life depends on Daf-2, Daf-16, Skn-1, and Hsf-1 genes. These results indicate that the antiaging mechanism of SVHRSP in nematodes might be mediated by the insulin/insulin-like growth factor-1 signaling pathway. Meanwhile, SVHRSP could also up-regulate the expression of stress-inducing genes Hsp-16.2, Sod-3, Gei-7, and Ctl-1 associated with aging. In general, our study may have important implications for SVHRSP to promote healthy aging and provide strategies for research and development of drugs to treat age-related diseases.

Engineered Carbon Nanostructures for Preventing Alzheimer’s Disease

Alzheimer’s disease (AD) is an aging-associated devastating disease that affects over 5 million Americans and imposes an annual economic burden of $236 billion. Currently, all efforts to develop remedies to AD have failed. This unfortunate situation calls for the development of new research directions. One of the common pathological features of AD is the decline in endogenous production of hydrogen sulfide (H2S), a gaseous signaling molecule. H2S in the brain is historically believed to be solely derived via enzymatic production and deficiencies in H2S producing enzymes, such as cystathionine-γ-lyase (CGL) and cystathionine-β-synthase (CBS) are associated with neurodegenerative diseases. Exogenous administration of H2S and H2S donors have shown to attenuate Alzheimer’s and Parkinson’s disease phenotypes in rodent models. However, exogenous H2S gas and donor molecules are short-lived, highly reactive, and display acute toxicity at elevated levels, and delivery to the intended tissue may be challenging to achieve in the clinic. Thus, discovering new technologies that regulate and/or augment endogenous enzymatic H2S pose novel scientific and therapeutic avenues particularly for the treatment of neurodegenerative disorders such as Alzheimer’s disease.We are designing enzyme-mimicking carbon nanostructures (EMCNs) that can augment the production of H2S using biological substrates present in the body and compensate for the declining enzyme activity and prevent the progression of Alzheimer’s disease. Carbon nanostructures with sp2 carbons are composed of multiple electron-deficient double bonds, which can be systematically replaced with functional groups to create a heterogeneous surface that is fundamentally different from that originally present. Based on the sp2 site engineering concept, we selected and synthesized EMCNs capable of interacting with the sulfur-containing biomolecules, catalyzing their breakdown into H2S and other products, thus mimicking CGL and CBS enzymes.The ability of EMCNs to mimic enzymes was evaluated with lead acetate saturated paper-based assay. EMCNs break down cysteine to produce H2S, which reacts with lead acetate to form lead sulfide. The concentration of H2S generated is calculated by using sodium hydrosulfide as an equimolar H2S donor for calibration. The H2S generation from EMCNs can be matched with the CBS enzyme. Further, EMCNs are stable and demonstrate long-term activity. In a repeated exposure experiment, H2S production was constant over a 20 day period where the substrate was added every day without replenishing ECMNs. If EMCNs were a reactant, the H2S production should have decreased with repeated substrate addition until all the EMCN was consumed.The efficacy of EMCNs to produce H2S in vitro was demonstrated with murine neuronal cells. P3 multi-photon fluorescent probe was utilized to detect intracellular H2S levels. The fluorescence intensity of the neuronal cells exposed to EMCN increased in a concentration-dependent manner. Neither cells nor EMCN exhibited auto-fluorescence under multi-photon microscopy. Beta-amyloid (Aβ) plaques, a hallmark of brain pathology in Alzheimer's disease patients, is formed by aggregation of β-amyloid peptides. The role of EMCNs in the AD model was evaluated with β-amyloid toxicity assay using Aβ1-42, which is selectively toxic to neurons. Preliminary studies suggest that EMCNs protect neuronal cells against the toxicity induced by Aβ1-42 by 19%. The ability of EMCNs to produce H2S under physiological conditions thus offers potential for rescuing enzyme deficiencies in Alzheimer’s disease.

Actions of the TrkB Agonist Antibody ZEB85 in Regulating the Architecture and Synaptic Plasticity in Hippocampal Neurons.

Signaling of BDNF via its TrkB receptor is crucial in regulating several critical aspects of the architecture and function of neurons both during development and in the adult central nervous system. Indeed, several neurological conditions, such as neurodevelopmental and neurodegenerative disorders are associated with alterations both in the expression levels of BDNF and TrkB, and in their intracellular signaling. Thus, the possibility of promoting BDNF/TrkB signaling has become relevant as a potential therapeutic intervention for neurological disorders. However, the clinical potential of BDNF itself has been limited due to its restricted diffusion rate in biological tissue, poor bioavailability and pharmacological properties, as well as the potential for unwanted side effects due to its ability to also signal via the p75NTR pathway. Several small molecule and biologic drug candidate TrkB agonists have been developed and are reported to have effects in rescuing both the pathological alterations and disease related symptoms in mouse models of several neurological diseases. However, recent side-by-side comparative studies failed to show their specificity for activating TrkB signaling cascades, suggesting the need for the generation and validation of improved candidates. In the present study, we examine the ability of the novel, fully human TrkB agonist antibody ZEB85 to modulate the architecture, activity and synaptic plasticity of hippocampal murine neurons under physiological conditions. Moreover, we show here that ZEB85 prevents β-amyloid toxicity in cultured hippocampal neurons, in a manner which is comparable to BDNF.

Neuroprotective Profile of Edible Flowers of Borage (Borago officinalis L.) in Two Different Models: Caenorhabditis elegans and Neuro-2a Cells.

The flowers of Borago officinalis L. (Boraginaceae), commonly known as borage, are widely used as a culinary ingredient. The aim of this study was to assess the potential benefits of fresh borage flower extract related to antioxidant, neuroprotective and anti-aging properties. The extract was obtained by Soxhlet extraction with ethanol as a solvent, and fatty acids were detected by GC-FID. The antioxidant activity was evaluated in vitro through the DPPH, FRAP and ORAC assays. Regarding the fatty acid (FA) composition, the extract showed high amounts of polyunsaturated FA. The Neuro-2a cell line was used to determine the cytoprotective capacity of the extract subjected to oxidative stress (H2O2). Moreover, the model organism Caenorhabditis elegans was used to assess antioxidant activity, delayed ageing as well as cytoprotection and reduced β-amyloid toxicity. Cells treated with the extract and H2O2 showed a better response to oxidative stress than the control group, particularly in terms of mitochondrial activity (MTT assay), redox state (ROS formation) and the activity of antioxidant enzymes (catalase and superoxide dismutase). B. officinalis flower extract showed promising antioxidant activity in the selected models, without causing toxicity. Hence, the results obtained support the antioxidant properties of borage flowers in different bioassays using living organisms.

An integrated genome and phenome-wide association study approach to understanding Alzheimer's disease predisposition

Genome-wide association studies (GWAS) have identified common single nucleotide polymorphisms (SNPs) that increase late-onset Alzheimer's disease (LOAD) risk. To identify additional LOAD-associated variants and provide insight into underlying disease biology, we performed a phenome-wide association study on 23 known LOAD-associated SNPs and 4:1 matched control SNPs using UK Biobank data. LOAD-associated SNPs were significantly enriched for associations with 8/778 queried traits, including 3 platelet traits. The strongest enrichment was for platelet distribution width (PDW) (p = 1.2 × 10−5), but increased PDW was not associated with LOAD susceptibility in Mendelian randomization analysis. Of 384 PDW-associated SNPs identified by prior GWAS, 36 were nominally associated with LOAD risk (17,008 cases; 37,154 controls) and 5 survived false-discovery rate correction. Associations confirmed known LOAD risk loci near PICALM, CD2AP, SPI1, and NDUFAF6, and identified a novel risk locus in epidermal growth factor receptor. Integrating GWAS and phenome-wide association study data reveals substantial pleiotropy between genetic determinants of LOAD and of platelet morphology, and for the first time implicates epidermal growth factor receptor – a mediator of β-amyloid toxicity – in Alzheimer's disease susceptibility.