Crosstalk between Oxidative Stress and Tauopathy

Development of MAPT S305 mutation human iPSC lines exhibiting elevated 4R tau expression and functional alterations in neurons and astrocytes

Due to the importance of 4R tau (with four microtubule-binding-repeat domains) in the pathogenicity of primary tauopathies, it has been challenging to model these diseases in induced pluripotent stem cell (iPSC)-derived neurons, which express very low levels of 4R tau. To address this, we have developed a panel of isogenic iPSC lines carrying MAPT splice-site mutations, S305S, S305I, or S305N, derived from four different donors. All mutations significantly increase 4R tau expression in iPSC neurons and astrocytes. Functional analyses of S305 mutant neurons reveal shared disruption in synaptic signaling and maturity but divergent effects on mitochondrial bioenergetics. In iPSC astrocytes, S305 mutations promote internalization of exogenous tau that may be a precursor to glial pathology. These lines recapitulate previously characterized tauopathy-relevant phenotypes and highlight functional differences between the wild-type 4R and the mutant 4R proteins in both neurons and astrocytes. As such, these lines enable a more complete understanding of pathogenic mechanisms underlying 4R tauopathies across different cell types.

Detecting the Undetectable: Advances in Methods for Identifying Small Tau Aggregates in Neurodegenerative Diseases

Tau, a microtubule-associated protein, plays a critical role in maintaining neuronal structure and function. However, in neurodegenerative diseases such as Alzheimer's disease and other tauopathies, tau misfolds and aggregates into oligomers and fibrils, leading to neuronal damage. Tau oligomers are increasingly recognised as the most neurotoxic species, inducing synaptic dysfunction and contributing to disease progression. Detecting these early-stage aggregates is challenging due to their low concentration and high heterogeneity in biological samples. Traditional methods such as immunostaining and enzyme-linked immunosorbent assay (ELISA) lack the sensitivity and specificity to reliably detect small tau aggregates. Advanced single-molecule approaches, including single-molecule fluorescence resonance energy transfer (smFRET) and single-molecule pull-down (SiMPull), offer improved sensitivity for studying tau aggregation at the molecular level. These emerging tools provide critical insights into tau pathology, enabling earlier detection and characterisation of disease-relevant aggregates, thereby offering potential for the development of targeted therapies and diagnostic approaches for tauopathies.

Polyphenol Mediated Assembly: Tailored Nano-Dredger Unblocks Axonal Autophagosomes Retrograde Transport Traffic Jam for Accelerated Alzheimer's Waste Clearance

Clear-cut evidence has linked defective autophagy to Alzheimer's disease (AD). Recent studies underscore a unique hurdle in AD neuronal autophagy: impaired retrograde axonal transport of autophagosomes, potent enough to induce autophagic stress and neurodegeneration. Nonetheless, pertinent therapy is unavailable. Here, a novel combinational therapy composed of siROCK2 and lithospermic acid B (LA) is introduced, tailored to dredge blocked axonal autophagy by multi-mitigating microtubule disruption, ATP depletion, oxidative stress, and autophagy initiation impediments in AD. Leveraging the recent discovery of multi-interactions between polyphenol LA and siRNA, ε-Poly-L-lysine, and anionic lipid nanovacuoles, LA and siROCK2 are successfully co-loaded into a fresh nano-drug delivery system, LIP@PL-LA/siRC, via a ratio-flexible and straightforward fabrication process. Further modification with the TPL peptide onto LIP@PL-LA/siRC creates a brain-neuron targeted, biocompatible, and pluripotent nanomedicine, named "Nano-dredger" (T-LIP@PL-LA/siRC). Nano-dredger efficiently accelerates axonal retrograde transport and lysosomal degradation of autophagosomes, thereby facilitating the clearance of neurotoxic proteins, improving neuronal complexity, and alleviating memory defects in 3×Tg-AD transgenic mice. This study provides a fresh and flexible polyphenol/siRNA co-delivery paradigm and furnishes conceptual proof that dredging axonal autophagy represents a promising AD therapeutic avenue.

The multiple roles of chronic stress and glucocorticoids in Alzheimer's disease pathogenesis

Chronic stress and the accompanying long-term elevation of glucocorticoids (GCs), the stress hormones of the body, increase the risk and accelerate the progression of Alzheimer's disease (AD). Signatures of AD include intracellular tau (MAPT) tangles, extracellular amyloid β (Aβ) plaques, and neuroinflammation. A growing body of work indicates that stress and GCs initiate cellular processes underlying these pathologies through dysregulation of protein homeostasis and trafficking, mitochondrial bioenergetics, and response to damage-associated stimuli. In this review, we integrate findings from mechanistic studies in rodent and cellular models, wherein defined chronic stress protocols or GC administration have been shown to elicit AD-related pathology. We specifically discuss the effects of chronic stress and GCs on tau pathogenesis, including hyperphosphorylation, aggregation, and spreading, amyloid precursor protein (APP) processing and trafficking culminating in Aβ production, immune priming by proinflammatory cytokines and disease-associated molecular patterns, and alterations to glial cell and blood-brain barrier (BBB) function.

Asymmetric Dearomatization of Indoles through Cobalt-Catalyzed Enantioselective C-H Functionalization Enabled by Photocatalysis

Photocatalysis holds a pivotal position in modern organic synthesis, capable of inducing novel reactivities under mild and environmentally friendly reaction conditions. However, the merger of photocatalysis and transition-metal-catalyzed asymmetric C-H activation as an efficient and sustainable method for the construction of chiral molecules remains elusive and challenging. Herein, we develop a cobalt-catalyzed enantioselective C-H activation reaction enabled by visible-light photoredox catalysis, providing a synergistic catalytic strategy for the asymmetric dearomatization of indoles with high levels of enantioselectivity (96 % to >99 % ee). Mechanistic studies indicate that the excited photocatalyst was quenched by divalent cobalt species in the presence of Salox ligand, leading to the formation of catalytically active chiral Co(III) complex. Moreover, stoichiometric reactions of cobaltacycle intermediate with indole suggest that the irradiation of visible light also play a critical role in the dearomatization step.

Tau is required for glial lipid droplet formation and resistance to neuronal oxidative stress

The accumulation of reactive oxygen species (ROS) is a common feature of tauopathies, defined by Tau accumulations in neurons and glia. High ROS in neurons causes lipid production and the export of toxic peroxidated lipids (LPOs). Glia uptake these LPOs and incorporate them into lipid droplets (LDs) for storage and catabolism. We found that overexpressing Tau in glia disrupts LDs in flies and rat neuron-astrocyte co-cultures, sensitizing the glia to toxic, neuronal LPOs. Using a new fly tau loss-of-function allele and RNA-mediated interference, we found that endogenous Tau is required for glial LD formation and protection against neuronal LPOs. Similarly, endogenous Tau is required in rat astrocytes and human oligodendrocyte-like cells for LD formation and the breakdown of LPOs. Behaviorally, flies lacking glial Tau have decreased lifespans and motor defects that are rescuable by administering the antioxidant N-acetylcysteine amide. Overall, this work provides insights into the important role that Tau has in glia to mitigate ROS in the brain.

Using Synbiotics as a Therapy to Protect Mental Health in Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurological disorder that represents a major cause of dementia worldwide. Its pathogenesis involves multiple pathways, including the amyloid cascade, tau protein, oxidative stress, and metal ion dysregulation. Recent studies have suggested a critical link between changes in gut microbial diversity and the disruption of the gut-brain axis in AD. Previous studies primarily explored the potential benefits of probiotics and prebiotics in managing AD. However, studies have yet to fully describe a novel promising approach involving the use of synbiotics, which include a combination of active probiotics and new-generation prebiotics. Synbiotics show potential for mitigating the onset and progression of AD, thereby offering a holistic approach to address the multifaceted nature of AD. This review article primarily aims to gain further insights into the mechanisms of AD, specifically the intricate interaction between gut bacteria and the brain via the gut-brain axis. By understanding this relationship, we can identify potential targets for intervention and therapeutic strategies to combat AD effectively. This review also discusses substantial evidence supporting the role of synbiotics as a promising AD treatment that surpasses traditional probiotic or prebiotic interventions. We find that synbiotics may be used not only to address cognitive decline but also to reduce AD-related psychological burden, thus enhancing the overall quality of life of patients with AD.

Investigation of the expression of Cis P-tau and Pin1 proteins following air pollution induction in the brain tissue of C57BL/6 mice

Alzheimer's disease (AD) is a multifactorial disease in which environmental factors play a role. Among environmental factors, air pollution is a vital issue in modern life. Despite extensive considerations, it remains uncertain how pollution mediates neurodegeneration in AD. Beta-amyloids and hyperphosphorylated tau proteins are the two main pathological markers that have been studied in AD so far. Tau protein is basically a phosphoprotein whose functions are controlled by phosphorylation. The function of tau protein is to be located on the surface of microtubules and stabilize them. Studies have shown that phosphorylated tau protein (p-tau) exists in cis and trans conformations at Thr231, among which cis is highly neurotoxic. The Pin1 enzyme performs the conversion of cis to trans or vice versa. In this study, an experimental mouse model was designed to investigate the formation of cis p-tau by inducing air pollution. In this way, mice were randomly exposed to pollution at 2-week, 1-month, and 2-month intervals. We investigated the formation of phosphorylated cis tau form during air pollution on mouse brains using Western blots and immunofluorescence. The fluorescent imaging results and Western blotting analysis of mouse brains revealed a significant accumulation of cis p-tau in pollution-treated mice models compared to the healthy control mice. According to Western blot results, air pollution induction caused a significant decrease in Pin1 protein. The results clearly show that the tauopathy observed during air pollution is mediated through the formation of cis tau. Our findings unravel tauopathy mysteries upon pollution and would help find a possible therapeutic target to fight the devastating disorder caused by modern life.

ROS Chronicles in HIV Infection: Genesis of Oxidative Stress, Associated Pathologies, and Therapeutic Strategies

Reactive oxygen species (ROS) are widely regarded as signaling molecules and play essential roles in various cellular processes, but when present in excess, they can lead to oxidative stress (OS). Growing evidence suggests that the OS plays a critical role in the pathogenesis of HIV infection and is associated with several comorbidities in HIV-infected individuals. ROS, generated both naturally during mitochondrial oxidative metabolism and as a response to various cellular processes, can trigger host antiviral responses but can also promote viral replication. While the multifaceted roles of ROS in HIV pathophysiology clearly need more investigation, this review paper unravels the mechanisms of OS generation in the context of HIV infections, offering insights into HIV viral protein-mediated and antiretroviral therapy-generated OS. Though the viral protein Tat is significantly attributed to the endogenous cellular increase in ROS post HIV infection, this paper sums up the contribution of other viral proteins in HIV-mediated elicitation of ROS. Given the investigations recognizing the significant role of ROS in the onset and progression of diverse pathologies, the paper also explores the critical function of ROS in the mediation of an of array of pathologies associated with HIV infection and retroviral therapy. HIV patients are observed with disruption to the antioxidant defense system, the antioxidant therapy is gaining focus as a potential therapeutic intervention and is well discussed. While ROS play a significant role in the HIV scenario, further exploratory studies are imperative to identifying alternative therapeutic strategies that could mitigate the toxicities and pathologies associated with ART-induced OS.

A novel 3D nitrogen-doped porous carbon supported Fe-Cu bimetallic nanoparticles composite derived from lignin: an efficient peroxymonosulfate activator for naphthalene degradation

A novel 3D nitrogen-doped porous carbon supported Fe-Cu bimetallic nanoparticles composite (Fe-Cu-N-PC) was prepared via direct pyrolysis by employing black liquor lignin as a main precursor, and it was utilized as a novel catalyst for PMS activation in degrading naphthalene. Under the optimum experimental conditions, the naphthalene degradation rate was up to 93.2% within 60 min in the Fe-Cu-N-PC/PMS system. The porous carbon framework of Fe-Cu-N-PC could facilitate the quick molecule diffusion of reactants towards the inner bimetallic nanoparticles and enriched naphthalene molecules from the solution by a specific adsorption, which increased the odds of contact between naphthalene and reactive oxygen species and improved the reaction efficiency. The quenching reaction proved that the non-free radical pathway dominated by 1O2 was the main way in naphthalene degradation, while the free radical pathway involving SO4·- and ·OH only played a secondary role. Moreover, owing to its high magnetization performance, Fe-Cu-N-PC could be magnetically recovered and maintained excellent naphthalene degradation rate after four degradation cycles. This research will offer a theoretical basis for the construction of facile, efficient, and green technologies to remediate persistent organic pollutants in the environment.

Neuroprotective effect of whey protein hydrolysate containing leucine-aspartate-isoleucine-glutamine-lysine on HT22 cells in hydrogen peroxide-induced oxidative stress

This study aimed to investigate the neuroprotective effects of whey protein hydrolysate (WPH) containing the pentapeptide leucine-aspartate-isoleucine-glutamine-lysine (LDIQK). Whey protein hydrolysate (50, 100, and 200 µg/mL) demonstrated the ability to restore the viability of HT22 cells subjected to 300 µM hydrogen peroxide (H2O2)-induced oxidative stress. Furthermore, at a concentration of 200 µg/mL, it significantly reduced the increase in reactive oxygen species production and calcium ion (Ca2+) influx induced by H2O2 by 46.1% and 46.2%, respectively. Similarly, the hydrolysate significantly decreased the levels of p-tau, a hallmark of tauopathy, and BCL2 associated X (BAX), a proapoptosis factor, while increasing the protein levels of choline acetyltransferase (ChAT), an enzyme involved in acetylcholine synthesis, brain-derived neurotrophic factor (BDNF), a nerve growth factor, and B-cell lymphoma 2 (BCL2, an antiapoptotic factor. Furthermore, it increased nuclear factor erythroid 2-related factor 2 (Nrf2)-hemoxygenase-1(HO-1) signaling, which is associated with the antioxidant response, while reducing the activation of mitogen-activated protein kinase (MAPK) signaling pathway components, namely phosphor-extracellular signal-regulated kinases (p-ERK), phosphor-c-Jun N-terminal kinases (p-JNK), and p-p38. Column chromatography and tandem mass spectrometry analysis identified LDIQK as a compound with neuroprotective effects in WPH; it inhibited Ca2+ influx and regulated the BAX/BCL2 ratio. Collectively, WPH containing LDIQK demonstrated neuroprotective effects against H2O2-induced neuronal cell damage, suggesting that WPH or its active peptide, LDIQK, may serve as a potential edible agent for improving cognitive dysfunction.

In Vitro and In Vivo Insights into a Broccoli Byproduct as a Healthy Ingredient for the Management of Alzheimer's Disease and Aging through Redox Biology

Broccoli has gained popularity as a highly consumed vegetable due to its nutritional and health properties. This study aimed to evaluate the composition profile and the antioxidant capacity of a hydrophilic extract derived from broccoli byproducts, as well as its influence on redox biology, Alzheimer's disease markers, and aging in the Caenorhabditis elegans model. The presence of glucosinolate was observed and antioxidant capacity was demonstrated both in vitro and in vivo. The in vitro acetylcholinesterase inhibitory capacity was quantified, and the treatment ameliorated the amyloid-β- and tau-induced proteotoxicity in transgenic strains via SOD-3 and SKN-1, respectively, and HSP-16.2 for both parameters. Furthermore, a preliminary study on aging indicated that the extract effectively reduced reactive oxygen species levels in aged worms and extended their lifespan. Utilizing broccoli byproducts for nutraceutical or functional foods could manage vegetable processing waste, enhancing productivity and sustainability while providing significant health benefits.

The need for systems thinking to advance Alzheimer's disease research

Despite extensive research efforts to mechanistically understand late-onset Alzheimer's disease (LOAD) and other complex mental health disorders, curative treatments remain elusive. We emphasize the multiscale multicausality inherent to LOAD, highlighting the interplay between interconnected pathophysiological processes and risk factors. Systems thinking methods, such as causal loop diagrams and systems dynamic models, offer powerful means to capture and study this complexity. Recent studies developed and validated a causal loop diagram and system dynamics model using multiple longitudinal data sets, enabling the simulation of personalized interventions on various modifiable risk factors in LOAD. The results indicate that targeting factors like sleep disturbance and depressive symptoms could be promising and yield synergistic benefits. Furthermore, personalized interventions showed significant potential, with top-ranked intervention strategies differing significantly across individuals. We argue that systems thinking approaches can open new prospects for multifactorial precision medicine. In future research, systems thinking may also guide structured, model-driven data collection on the multiple interactions in LOAD's complex multicausality, facilitating theory development and possibly resulting in effective prevention and treatment options.

Role of oxidative stress in neurodegenerative disorders: a review of reactive oxygen species and prevention by antioxidants

Neurological disorders include a variety of conditions, including Alzheimer's disease, motor neuron disease and Parkinson's disease, affecting longevity and quality of life, and their pathogenesis is associated with oxidative stress. Several of the chronic neurodegenerative pathologies of the CNS share some common features, such as oxidative stress, inflammation, synapse dysfunctions, protein misfolding and defective autophagia. Neuroinflammation can involve the activation of mast cells, contributing to oxidative stress, in addition to other sources of reactive oxygen species. Antioxidants can powerfully neutralize reactive oxygen species and free radicals, decreasing oxidative damage. Antioxidant genes, like the manganese superoxide dismutase enzyme, can undergo epigenetic changes that reduce their expression, thus increasing oxidative stress in tissue. Alternatively, DNA can be altered by free radical damage. The epigenetic landscape of these genes can change antioxidant function and may result in neurodegenerative disease. This imbalance of free radical production and antioxidant function increases the reactive oxygen species that cause cell damage in neurons and is often observed as an age-related event. Increased antioxidant expression in mice is protective against reactive oxygen species in neurons as is the exogenous supplementation of antioxidants. Manganese superoxide dismutase requires manganese for its enzymic function. Antioxidant therapy is considered for age-related neurodegenerative diseases, and a new mimetic of a manganese superoxide dismutase, avasopasem manganese, is described and suggested as a putative treatment to reduce the oxidative stress that causes neurodegenerative disease. The aim of this narrative review is to explore the evidence that oxidative stress causes neurodegenerative damage and the role of antioxidant genes in inhibiting reactive oxygen species damage. Can the neuronal environment of oxidative stress, causing neuroinflammation and neurodegeneration, be reduced or reversed?

Development of MAPT S305 mutation models exhibiting elevated 4R tau expression, resulting in altered neuronal and astrocytic function

Due to the importance of 4R tau in the pathogenicity of primary tauopathies, it has been challenging to model these diseases in iPSC-derived neurons, which express very low levels of 4R tau. To address this problem we have developed a panel of isogenic iPSC lines carrying the MAPT splice-site mutations S305S, S305I or S305N, derived from four different donors. All three mutations significantly increased the proportion of 4R tau expression in iPSC-neurons and astrocytes, with up to 80% 4R transcripts in S305N neurons from as early as 4 weeks of differentiation. Transcriptomic and functional analyses of S305 mutant neurons revealed shared disruption in glutamate signaling and synaptic maturity, but divergent effects on mitochondrial bioenergetics. In iPSC-astrocytes, S305 mutations induced lysosomal disruption and inflammation and exacerbated internalization of exogenous tau that may be a precursor to the glial pathologies observed in many tauopathies. In conclusion, we present a novel panel of human iPSC lines that express unprecedented levels of 4R tau in neurons and astrocytes. These lines recapitulate previously characterized tauopathy-relevant phenotypes, but also highlight functional differences between the wild type 4R and mutant 4R proteins. We also highlight the functional importance of MAPT expression in astrocytes. These lines will be highly beneficial to tauopathy researchers enabling a more complete understanding of the pathogenic mechanisms underlying 4R tauopathies across different cell types.

Differential rescue effects of choline chloride and soy isolate on metabolic dysfunction in immature central nervous system neurons: Relevance to fetal alcohol spectrum disorder

Background

Central Nervous System (CNS) abnormalities with insulin resistance and mediated by developmental exposures to ethanol can be avoided or remediated by consumption of dietary soy, which has insulin-sensitizing as well as antioxidant effects. However, choline supplementation has been shown to diminish Fetal Alcohol Spectrum Disorder (FASD) pathologies, and dietary soy contains abundant choline. This study was designed to determine if the therapeutic effects of soy were mediated by or independent of choline.

Methods

Human PNET2 cells exposed to 0 mM or 100 mM ethanol for 48 hours were seeded into 96-well or 12-well plates and treated with vehicle, choline chloride (75 μM), or 1 μM Daidzein+1 μM Genistein (D+G) for 24 h. The cells were then analyzed for viability (Hoechst 33342), mitochondrial function (MTT), and GAPDH, Tau, Acetyl Cholinesterase (AChE), Choline Acetyl Transferase (ChAT), and Aspartyl-Asparaginyl-β-Hydroxylase (ASPH) immunoreactivity.

Results

Choline and D+G significantly increased MTT activity (mitochondrial function) corrected for cell number relative to vehicle in control and ethanol-exposed cultures. Both choline and D+G prevented the ethanol-induced inhibition of GAPDH and ChAT and increased cellular accumulations of Tau. However, D+G significantly increased ASPH expression relative to vehicle and Choline.

Conclusion

Choline and D+G differentially modulated the expression of neuronal proteins, mitochondrial function, and ASPH. Importantly, the prominently increased expression of ASPH by D+G corresponds with the insulin-sensitizer actions of soy isoflavones since ASPH is an insulin-responsive molecule. The findings further suggest that dietary soy may be more effective than choline for reducing ethanol-impaired neuronal migration linked to ASPH inhibition in FASD.

Levosimendan inhibits disulfide tau oligomerization and ameliorates tau pathology in TauP301L-BiFC mice

Tau oligomers play critical roles in tau pathology and are responsible for neuronal cell death and transmitting the disease in the brain. Accordingly, preventing tau oligomerization has become an important therapeutic strategy to treat tauopathies, including Alzheimer's disease. However, progress has been slow because detecting tau oligomers in the cellular context is difficult. Working toward tau-targeted drug discovery, our group has developed a tau-BiFC platform to monitor and quantify tau oligomerization. By using the tau-BiFC platform, we screened libraries with FDA-approved and passed phase I drugs and identified levosimendan as a potent anti-tau agent that inhibits tau oligomerization. ¹⁴C-isotope labeling of levosimendan revealed that levosimendan covalently bound to tau cysteines, directly inhibiting disulfide-linked tau oligomerization. In addition, levosimendan disassembles tau oligomers into monomers, rescuing neurons from aggregation states. In comparison, the well-known anti-tau agents methylene blue and LMTM failed to protect neurons from tau-mediated toxicity, generating high-molecular-weight tau oligomers. Levosimendan displayed robust potency against tau oligomerization and rescued cognitive declines induced by tauopathy in the Tau^P301L-BiFC mouse model. Our data present the potential of levosimendan as a disease-modifying drug for tauopathies.

Alzheimer’s Disease from the Amyloidogenic Theory to the Puzzling Crossroads between Vascular, Metabolic and Energetic Maladaptive Plasticity

Alzheimer’s disease (AD) is a progressive and degenerative disease producing the most common type of dementia worldwide. The main pathogenetic hypothesis in recent decades has been the well-known amyloidogenic hypothesis based on the involvement of two proteins in AD pathogenesis: amyloid β (Aβ) and tau. Amyloid deposition reported in all AD patients is nowadays considered an independent risk factor for cognitive decline. Vascular damage and blood–brain barrier (BBB) failure in AD is considered a pivotal mechanism for brain injury, with increased deposition of both immunoglobulins and fibrin. Furthermore, BBB dysfunction could be an early sign of cognitive decline and the early stages of clinical AD. Vascular damage generates hypoperfusion and relative hypoxia in areas with high energy demand. Long-term hypoxia and the accumulation within the brain parenchyma of neurotoxic molecules could be seeds of a self-sustaining pathological progression. Cellular dysfunction comprises all the elements of the neurovascular unit (NVU) and neuronal loss, which could be the result of energy failure and mitochondrial impairment. Brain glucose metabolism is compromised, showing a specific region distribution. This energy deficit worsens throughout aging. Mild cognitive impairment has been reported to be associated with a glucose deficit in the entorhinal cortex and in the parietal lobes. The current aim is to understand the complex interactions between amyloid β (Aβ) and tau and elements of the BBB and NVU in the brain. This new approach aimed at the study of metabolic mechanisms and energy insufficiency due to mitochondrial impairment would allow us to define therapies aimed at predicting and slowing down the progression of AD.

Unexpected Classes of Aquaporin Channels Detected by Transcriptomic Analysis in Human Brain Are Associated with Both Patient Age and Alzheimer’s Disease Status

The altered expression of known brain Aquaporin (AQP) channels 1, 4 and 9 has been correlated with neuropathological AD progression, but possible roles of other AQP classes in neurological disease remain understudied. The levels of transcripts of all thirteen human AQP subtypes were compared in healthy and Alzheimer’s disease (AD) brains by statistical analyses of microarray RNAseq expression data from the Allen Brain Atlas database. Previously unreported, AQPs 0, 6 and 10, are present in human brains at the transcript level. Three AD-affected brain regions, hippocampus (HIP), parietal cortex (PCx) and temporal cortex (TCx), were assessed in three subgroups: young controls (n = 6, aged 24–57); aged controls (n = 26, aged 78–99); and an AD cohort (n = 12, aged 79–99). A significant positive correlation (p < 10−10) was seen for AQP transcript levels as a function of the subject’s age in years. Differential expressions correlated with brain region, age, and AD diagnosis, particularly between the HIP and cortical regions. Interestingly, three classes of AQPs (0, 6 and 8) upregulated in AD compared to young controls are permeable to H2O2. Of these, AQPs 0 and 8 were increased in TCx and AQP6 in HIP, suggesting a role of AQPs in AD-related oxidative stress. The outcomes here are the first to demonstrate that the expression profile of AQP channels in the human brain is more diverse than previously thought, and transcript levels are influenced by both age and AD status. Associations between reactive oxygen stress and neurodegenerative disease risk highlight AQPs 0, 6, 8 and 10 as potential therapeutic targets.

Neurodegenerative disorders: Assessing the impact of natural vs drug-induced treatment options

Neurodegenerative illnesses refer to the gradual, cumulative loss of neural activity. Neurological conditions are considered to be the second leading cause of mortality in the modern world and the two most prevalent ones are Parkinson's disease and Alzheimer's disease. The negative side effects of pharmaceutical use are a major global concern, despite the availability of many different treatments for therapy. We concentrated on different types of neurological problems and their influence on targets, in vitro, in vivo, and in silico methods toward neurological disorders, as well as the molecular approaches influencing the same, in the first half of the review. The bulk of the second half of the review focuses on the many categories of treatment possibilities, including natural and artificial. Nevertheless, herbal treatment solutions are piquing scholarly attention due to their anti-oxidative properties and accessibility. However, more quality investigations and innovations are undoubtedly needed to back up these conclusions.

Nature's Toolbox Against Tau Aggregation: An Updated Review of Current Research

Tau aggregation is a hallmark of several neurodegenerative disorders, such as Alzheimer's disease (AD), frontotemporal dementia, and progressive supranuclear palsy. Hyperphosphorylated tau is believed to contribute to the degeneration of neurons and the development of these complex diseases. Therefore, one potential treatment for these illnesses is to prevent or counteract tau aggregation. In recent years, interest has been increasing in developing nature-derived tau aggregation inhibitors as a potential treatment for neurodegenerative disorders. Researchers have become increasingly interested in natural compounds with multifunctional features, such as flavonoids, alkaloids, resveratrol, and curcumin, since these molecules can interact simultaneously with the various targets of AD. Recent studies have demonstrated that several natural compounds can inhibit tau aggregation and promote the disassembly of pre-formed tau aggregates. Nature-derived tau aggregation inhibitors hold promise as a potential treatment for neurodegenerative disorders. However, it is important to note that more research is needed to fully understand the mechanisms by which these compounds exert their effects and their safety and efficacy in preclinical and clinical studies. Nature-derived inhibitors of tau aggregation are a promising new direction in the research of neurodegenerative complexities. This review focuses on the natural products that have proven to be a rich supply for inhibitors in tau aggregation and their uses in neurodegenerative complexities, including AD.

Two pathways differentially linking tau depositions, oxidative stress, and neuronal loss to apathetic phenotypes in progressive supranuclear palsy

Patients with progressive supranuclear palsy (PSP) frequently exhibit apathy but the neuropathological processes leading to this phenotype remain elusive. We aimed to examine the involvement of tau protein depositions, oxidative stress (OS), and neuronal loss in the apathetic manifestation of PSP. Twenty patients with PSP and twenty-three healthy controls were enrolled. Tau depositions and brain volumes were evaluated via positron-emission tomography (PET) using a specific probe, ¹⁸F-PM-PBB3, and magnetic resonance imaging, respectively. Glutathione (GSH) levels in the anterior and posterior cingulate cortices were quantified by magnetic resonance spectroscopy. Tau pathologies were observed in the subcortical and cortical structures of the patient brains. The angular gyrus exhibited a positive correlation between tau accumulations and apathy scale (AS). Although PSP cases did not show GSH level alterations compared with healthy controls, GSH levels in posterior cingulate cortex were correlated with AS and tau depositions in the angular gyrus. Marked atrophy was observed in subcortical areas, and gray matter volumes in the inferior frontal gyrus and anterior cingulate cortex were positively correlated with AS but showed no correlation with tau depositions and GSH levels. Path analysis highlighted synergistic contributions of tau pathologies and GSH reductions in the posterior cortex to AS, in parallel with associations of gray matter atrophy in the anterior cortex with AS. Apathetic phenotypes may arise from PET-visible tau aggregation and OS compromising the neural circuit resilience in the posterior cortex, along with neuronal loss, with neither PET-detectable tau pathologies nor OS in the anterior cortex.

Losartan Mitigates Oxidative Stress in the Brains of Aged and Inflamed IL-10-/- Mice

Chronic inflammation, oxidative stress, and dysregulation of the renin-angiotensin system are closely linked, and their crosstalk commonly contributes to age-related physical and cognitive decline. The primary dementia-protective benefits of Angiotensin II type 1 receptor (AT1R) blockers are believed to arise from systemic effects on blood pressure. However, there is an independently regulated brain-specific renin-angiotensin system. Here, we examined the impact of 4 weeks of oral Losartan treatment on the brains of aged (100 weeks old) IL-10-/- mice, an animal model of chronic inflammation and frailty. Our data show that aged IL-10-/- mice have higher AT1R and Nitrotyrosine (oxidative stress marker) levels in their frontal cortex tissue but not in cerebellar or hippocampal tissue compared to age- and sex-matched wild type mice. Losartan treatment for 4 weeks is associated with lower AT1R protein level, Nitrotyrosine, and Tau protein in the frontal cortex of aged IL-10-/- mice. Our results highlight the impact of Losartan, an AT1R blocker commonly prescribed for treating high blood pressure, on the brain-specific angiotensin system and AT1R-linked downstream effects such as brain oxidative stress damage and Tau burden in a frailty mouse model.

The Mechanism of TNF-α-Mediated Accumulation of Phosphorylated Tau Protein and Its Modulation by Propofol in Primary Mouse Hippocampal Neurons: Role of Mitophagy, NLRP3, and p62/Keap1/Nrf2 Pathway

Background

Neuroinflammation-induced phosphorylated Tau (p-Tau) deposition in central nervous system contributes to neurodegenerative disorders. Propofol possesses neuroprotective properties. We investigated its impacts on tumor necrosis factor-α (TNF-α)-mediated p-Tau deposition in neurons.

Methods

Mouse hippocampal neurons were exposed to propofol followed by TNF-α. Cell viability, p-Tau, mitophagy, reactive oxygen species (ROS), NOD-like receptor protein 3 (NLRP3), antioxidant enzymes, and p62/Keap1/Nrf2 pathway were investigated.

Results

TNF-α promoted p-Tau accumulation in a concentration- and time-dependent manner. TNF-α (20 ng/mL, 4 h) inhibited mitophagy while increased ROS accumulation and NLRP3 activation. It also induced glycogen synthase kinase-3β (GSK3β) while inhibited protein phosphatase 2A (PP2A) phosphorylation. All these effects were attenuated by 25 μM propofol. In addition, TNF-α-induced p-Tau accumulation was attenuated by ROS scavenger, NLRP3 inhibitor, GSK3β inhibitor, or PP2A activator. Besides, compared with control neurons, 100 μM propofol decreased p-Tau accumulation. It also decreased ROS and NLRP3 activation, modulated GSK3β/PP2A phosphorylation, leaving mitophagy unchanged. Further, 100 μM propofol induced p62 expression, reduced Keap1 expression, triggered the nuclear translocation of Nrf2, and upregulated superoxide dismutase (SOD) and heme oxygenase-1 (HO-1) expression, which was abolished by p62 knockdown, Keap1 overexpression, or Nrf2 inhibitor. Consistently, the inhibitory effect of 100 μM propofol on ROS and p-Tau accumulation was mitigated by p62 knockdown, Keap1 overexpression, or Nrf2 inhibitor.

Conclusions

In hippocampal neurons, TNF-α inhibited mitophagy, caused oxidative stress and NLRP3 activation, leading to GSK3β/PP2A-dependent Tau phosphorylation. Propofol may reduce p-Tau accumulation by reversing mitophagy and oxidative stress-related events. Besides, propofol may reduce p-Tau accumulation by modulating SOD and HO-1 expression through p62/Keap1/Nrf2 pathway.

The heart as a target for deltamethrin toxicity: Inhibition of Nrf2/HO-1 pathway induces oxidative stress and results in inflammation and apoptosis

As a synthetic pyrethroid pesticide, deltamethrin (DLM) is widely employed in veterinary medicine and farming, and DLM-triggered oxidative stress largely causes serious harm to the organism. It is well-known that nuclear factor erythroid-2-related factor 2/heme oxygenase-1 (Nrf2/HO-1), a pivotal endogenous anti-oxidative pathway, acts on inhibiting oxidative stress-induced cell injury under the activated state. The purpose of this research was to observe the impact and molecular mechanism of DLM on inflammation and apoptosis in quail cardiomyocytes based on the Nrf2/HO-1 signaling route. In this research, quails were established as a cardiac injury model through gastric infusion of various doses of DLM (0, 15, 30, and 45 mg/kg b. w.) for 12 weeks. Our results showed that DLM could induced cardiomyocyte injury in a dose-dependent manner though weakening antioxidant defense via down-regulating Nrf2 and its downstream protein HO-1. Furthermore, DLM stimulation induced apoptosis in quail heart by decreasing the protein expressions of B-cell lymphoma-extra large and B-cell lymphoma gene 2 (Bcl-2), as well as increasing P53, caspase 3, and Bcl-2-associated X protein levels. Meanwhile, relative levels of nuclear factor-kappa B and interleukin-1β in quail hearts were up-regulated under DLM intervention progressively. Collectively, our study demonstrates that chronic exposure to DLM can induce quail cardiomyocyte inflammation and apoptosis by mediating Nrf2/HO-1 signaling pathway-related oxidative stress.

Jatamansinol from Nardostachys jatamansi Ameliorates Tau-Induced Neurotoxicity in Drosophila Alzheimer's Disease Model

Nardostachys jatamansi has long been used to prepare Medhya Rasayana in traditional Indian Ayurveda medicine to treat neurological disorders and enhance memory. Jatamansinol from the N. jatamansi against Alzheimer's disease (AD) showed that it could be a multitargeted drug against AD. Drosophila is an ideal model organism for studying a progressive age-related neurodegenerative disease such as AD since its neuronal organizations and functioning are highly similar to that of humans. The current study investigates the neuroprotective properties of jatamansinol against Tau-induced neurotoxicity in the AD Drosophila model. Results indicate jatamansinol is not an antifeedant for larva and adult Drosophila. Lifespan, locomotor activity, learning and memory, Tau protein expression level, eye degeneration, oxidative stress level, and cholinesterase activities were analyzed in 10, 20, and 30-day-old control (wild type), and tauopathy flies reared on jatamansinol supplemented food or regular food without jatamansinol supplementation. Jatamansinol treatment significantly extends the lifespan, improves locomotor activity, enhances learning and memory, and reduces Tau protein levels in tauopathy flies. It boosts the antioxidant enzyme activities, prevents Tau-induced oxidative stress, ameliorates eye degeneration, and inhibits cholinesterase activities in Tau-induced AD model. This study provides the first evidence that jatamansinol protects against Tau's neurotoxic effect in the AD Drosophila model, and it can be a potential therapeutic drug candidate for AD.

Model scenarios for cell cycle re-entry in Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease. Aberrant production and aggregation of amyloid beta (Aβ) peptide into plaques is a frequent feature of AD, but therapeutic approaches targeting Aβ accumulation fail to inhibit disease progression. The approved cholinesterase inhibitor drugs are symptomatic treatments. During human brain development, the progenitor cells differentiate into neurons and switch to a postmitotic state. However, cell cycle re-entry often precedes loss of neurons. We developed mathematical models of multiple routes leading to cell cycle re-entry in neurons that incorporate the crosstalk between cell cycle, neuronal, and apoptotic signaling mechanisms. We show that the integration of multiple feedback loops influences disease severity making the switch to pathological state irreversible. We observe that the transcriptional changes associated with this transition are also characteristics of the AD brain. We propose that targeting multiple arms of the feedback loop may bring about disease-modifying effects in AD.

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Developed mathematical models of cell cycle re-entry in Alzheimer's disease (AD)

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Integration of multiple feedback loops drives irreversible transition to AD

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Predicted transcriptional dysregulation is validated using AD gene expression data

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Inhibition of self-amplifying feedback loops brings about disease-modifying effects

Dysfunction of Mitochondria in Alzheimer’s Disease: ANT and VDAC Interact with Toxic Proteins and Aid to Determine the Fate of Brain Cells

Alzheimer’s disease (AD), certainly the most widespread proteinopathy, has as classical neuropathological hallmarks, two groups of protein aggregates: senile plaques and neurofibrillary tangles. However, the research interest is rapidly gaining ground in a better understanding of other pathological features, first, of all the mitochondrial dysfunctions. Several pieces of evidence support the hypothesis that abnormal mitochondrial function may trigger aberrant processing of amyloid progenitor protein or tau and thus neurodegeneration. Here, our aim is to emphasize the role played by two ‘bioenergetic’ proteins inserted in the mitochondrial membranes, inner and outer, respectively, that is, the adenine nucleotide translocator (ANT) and the voltage-dependent anion channel (VDAC), in the progression of AD. To perform this, we will magnify the ANT and VDAC defects, which are measurable hallmarks of mitochondrial dysfunction, and collect all the existing information on their interaction with toxic Alzheimer’s proteins. The pathological convergence of tau and amyloid β-peptide (Aβ) on mitochondria may finally explain why the therapeutic strategies used against the toxic forms of Aβ or tau have not given promising results separately. Furthermore, the crucial role of ANT-1 and VDAC impairment in the onset/progression of AD opens a window for new therapeutic strategies aimed at preserving/improving mitochondrial function, which is suspected to be the driving force leading to plaque and tangle deposition in AD.

TCHis mitigate oxidative stress and improve abnormal behavior in a prenatal valproic acid-exposed rat model of autism

Objective Troxerutin is known for its anti-inflammatory and antioxidative effects in nerve impairment. The purpose of this study is to investigate the effect of troxerutin and cerebroprotein hydrolysate injections (TCHis) on prenatal valproic acid (VPA)-exposed rats. Methods The VPA was administered to pregnant rats on gestational day 12.5 to induce a model of autism. The offsprings were given the treatment of TCHis on postnatal day (PND) 21-50. On PND 43-50, the behavioral analysis of offsprings was performed after the treatment of TCHis for 1 h. On PND 50, the offsprings were harvested and the brains were collected. The hippocampus and prefrontal cortex were isolated for relevant biochemical detections. Results The administration of TCHis increased the pain sensitivity and improved abnormal social behaviors in prenatal VPA-exposed rats. Prenatal expose of VPA induced neuronal loss and apoptosis, enhanced reactive oxygen species (ROS) production, and promoted oxidative stress in hippocampus and prefrontal cortex, while these effects were reversed by the postnatal treatment of TCHis. In addition, postnatal administration of TCHis ameliorated mitochondrial function in hippocampus and prefrontal cortex of prenatal VPA-exposed rats. Conclusion This study concluded that postnatal treatment of TCHis reduced oxidative stress and ameliorated abnormal behavior in a prenatal VPA-induced rat model of autism.

Implication of type 4 NADPH oxidase (NOX4) in tauopathy

Aggregates of the microtubule-associated protein tau are a common marker of neurodegenerative diseases collectively termed as tauopathies, such as Alzheimer's disease (AD) and frontotemporal dementia. Therapeutic strategies based on tau have failed in late stage clinical trials, suggesting that tauopathy may be the consequence of upstream causal mechanisms. As increasing levels of reactive oxygen species (ROS) may trigger protein aggregation or modulate protein degradation and, we had previously shown that the ROS producing enzyme NADPH oxidase 4 (NOX4) is a major contributor to cellular autotoxicity, this study was designed to evaluate if NOX4 is implicated in tauopathy. Our results show that NOX4 is upregulated in patients with frontotemporal lobar degeneration and AD patients and, in a humanized mouse model of tauopathy induced by AVV-TauP301L brain delivery. Both, global knockout and neuronal knockdown of the Nox4 gene in mice, diminished the accumulation of pathological tau and positively modified established tauopathy by a mechanism that implicates modulation of the autophagy-lysosomal pathway (ALP) and, consequently, improving the macroautophagy flux. Moreover, neuronal-targeted NOX4 knockdown was sufficient to reduce neurotoxicity and prevent cognitive decline, even after induction of tauopathy, suggesting a direct and causal role for neuronal NOX4 in tauopathy. Thus, NOX4 is a previously unrecognized causative, mechanism-based target in tauopathies and blood-brain barrier permeable specific NOX4 inhibitors could have therapeutic potential even in established disease.

Oxidative stress in cancer therapy: Friend or enemy?

Excessive cellular oxidative stress is widely perceived as a key factor in pathophysiological conditions and cancer development. Healthy cells use several mechanisms to maintain intracellular levels of reactive oxygen species (ROS) and overall redox homeostasis to avoid damage to DNA, proteins, and lipids. Cancer cells, in contrast, exhibit elevated ROS levels and upregulated protective antioxidant pathways. Counterintuitively, such elevated oxidative stress and enhanced antioxidant defence mechanisms in cancer cells provide a therapeutic opportunity for the development of drugs with different anticancer mechanisms of action (MoA). In this review, oxidative stress and the role of ROS in cells are described. The tumour-suppressive and tumour-promotive functions of ROS are discussed to compare these two different therapeutic strategies (increasing or decreasing ROS to fight cancer). Clinically approved drugs with demonstrated oxidative stress anticancer MoAs are highlighted before describing examples of metal-based anticancer drug candidates causing oxidative stress in cancer cells via novel MoAs.

Flavones 7,8-DHF, Quercetin, and Apigenin Against Tau Toxicity via Activation of TRKB Signaling in ΔK280 TauRD-DsRed SH-SY5Y Cells

Alzheimer’s disease (AD) is a progressive neurodegenerative disease with memory loss and cognitive decline. Neurofibrillary tangles (NFTs) formed by hyperphosphorylated Tau protein are one of the pathological hallmarks of several neurodegenerative diseases including AD. Heat shock protein family B (small) member 1 (HSPB1) is a molecular chaperone that promotes the correct folding of other proteins in response to environmental stress. Nuclear factor erythroid 2-like 2 (NRF2), a redox-regulated transcription factor, is the master regulator of the cellular response to excess reactive oxygen species. Tropomyosin-related kinase B (TRKB) is a membrane-bound receptor that, upon binding brain-derived neurotrophic factor (BDNF), phosphorylates itself to initiate downstream signaling for neuronal survival and axonal growth. In this study, four natural flavones such as 7,8-dihydroxyflavone (7,8-DHF), wogonin, quercetin, and apigenin were evaluated for Tau aggregation inhibitory activity and neuroprotection in SH-SY5Y neuroblastoma. Among the tested flavones, 7,8-DHF, quercetin, and apigenin reduced Tau aggregation, oxidative stress, and caspase-1 activity as well as improved neurite outgrowth in SH-SY5Y cells expressing ΔK280 Tau_RD-DsRed folding reporter. Treatments with 7,8-DHF, quercetin, and apigenin rescued the reduced HSPB1 and NRF2 and activated TRKB-mediated extracellular signal-regulated kinase (ERK) signaling to upregulate cAMP-response element binding protein (CREB) and its downstream antiapoptotic BCL2 apoptosis regulator (BCL2). Knockdown of TRKB attenuated the neuroprotective effects of these three flavones. Our results suggest 7,8-DHF, quercetin, and apigenin targeting HSPB1, NRF2, and TRKB to reduce Tau aggregation and protect cells against Tau neurotoxicity and may provide new treatment strategies for AD.

Curcumin-Piperlongumine Hybrids with a Multitarget Profile Elicit Neuroprotection in In Vitro Models of Oxidative Stress and Hyperphosphorylation

Curcumin shows a broad spectrum of activities of relevance in the treatment of Alzheimer’s disease (AD); however, it is poorly absorbed and is also chemically and metabolically unstable, leading to a very low oral bioavailability. A small library of hybrid compounds designed as curcumin analogues and incorporating the key structural fragment of piperlongumine, a natural neuroinflammation inhibitor, were synthesized by a two-step route that combines a three-component reaction between primary amines, β-ketoesters and α-haloesters and a base-promoted acylation with cinnamoyl chlorides. These compounds were predicted to have good oral absorption and CNS permeation, had good scavenging properties in the in vitro DPPH experiment and in a cellular assay based on the oxidation of dichlorofluorescin to a fluorescent species. The compounds showed low toxicity in two cellular models, were potent inductors of the Nrf2-ARE phase II antioxidant response, inhibited PHF6 peptide aggregation, closely related to Tau protein aggregation and were active against the LPS-induced inflammatory response. They also afforded neuroprotection against an oxidative insult induced by inhibition of the mitochondrial respiratory chain with the rotenone-oligomycin A combination and against Tau hyperphosphorylation induced by the phosphatase inhibitor okadaic acid. This multitarget pharmacological profile is highly promising in the development of treatments for AD and provides a good hit structure for future optimization efforts.

Anti-Oxidative, Anti-Inflammatory and Anti-Apoptotic Effects of Flavonols: Targeting Nrf2, NF-κB and p53 Pathways in Neurodegeneration

Neurodegenerative diseases are one of the leading causes of disability and death worldwide. Intracellular transduction pathways that end in the activation of specific transcription factors are highly implicated in the onset and progression of pathological changes related to neurodegeneration, of which those related to oxidative stress (OS) and neuroinflammation are particularly important. Here, we provide a brief overview of the key concepts related to OS- and neuroinflammation-mediated neuropathological changes in neurodegeneration, together with the role of transcription factors nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB). This review is focused on the transcription factor p53 that coordinates the cellular response to diverse genotoxic stimuli, determining neuronal death or survival. As current pharmacological options in the treatment of neurodegenerative disease are only symptomatic, many research efforts are aimed at uncovering efficient disease-modifying agents. Natural polyphenolic compounds demonstrate powerful anti-oxidative, anti-inflammatory and anti-apoptotic effects, partially acting as modulators of signaling pathways. Herein, we review the current understanding of the therapeutic potential and limitations of flavonols in neuroprotection, with emphasis on their anti-oxidative, anti-inflammatory and anti-apoptotic effects along the Nrf2, NF-κB and p53 pathways. A better understanding of cellular and molecular mechanisms of their action may pave the way toward new treatments.

Preclinical validation of a novel oral Edaravone formulation for treatment of frontotemporal dementia

Oxidative stress is a key factor in the pathogenesis of several neurodegenerative disorders and is involved in the accumulation of amyloid beta plaques and Tau inclusions. Edaravone (EDR) is a free radical scavenger that is approved for motor neuron disease and acute ischemic stroke. EDR alleviates pathologies and cognitive impairment of AD via targeting multiple key pathways in transgenic mice. Herein, we aimed to study the effect of EDR on Tau pathology in P301L mice; an animal model of frontotemporal dementia (FTD), at two age time points representing the early and late stages of the disease. A novel EDR formulation was utilized in the study and the drug was delivered orally in drinking water for 3 months. Then, behavioral tests were conducted followed by animal sacrifice and brain dissection. Treatment with EDR improved the reference memory and accuracy in the probe trial as evaluated in Morris water maze, as well as novel object recognition and significantly alleviated motor deficits in these mice. EDR also reduced the levels of 4-hydroxy-2-nonenal and 3-nitrotyrosine adducts. In addition, immunohistochemistry showed that EDR reduced tau phosphorylation and neuroinflammation and partially rescued neurons against oxidative neurotoxicity. Moreover, EDR attenuated downstream pathologies involved in Tau hyperphosphorylation. These results suggest that EDR may be a potential therapeutic agent for the treatment of FTD.

Improvement of cognitive performance by a nutraceutical formulation: Underlying mechanisms revealed by laboratory studies

Cognitive decline, decrease in neuronal function and neuronal loss that accompany normal aging and dementia are the result of multiple mechanisms, many of which involve oxidative stress. Herein, we review these various mechanisms and identify pharmacological and non-pharmacological approaches, including modification of diet, that may reduce the risk and progression of cognitive decline. The optimal degree of neuronal protection is derived by combinations of, rather than individual, compounds. Compounds that provide antioxidant protection are particularly effective at delaying or improving cognitive performance in the early stages of Mild Cognitive Impairment and Alzheimer's disease. Laboratory studies confirm alleviation of oxidative damage in brain tissue. Lifestyle modifications show a degree of efficacy and may augment pharmacological approaches. Unfortunately, oxidative damage and resultant accumulation of biomarkers of neuronal damage can precede cognitive decline by years to decades. This underscores the importance of optimization of dietary enrichment, antioxidant supplementation and other lifestyle modifications during aging even for individuals who are cognitively intact.

A Tau-Driven Adverse Outcome Pathway Blueprint Toward Memory Loss in Sporadic (Late-Onset) Alzheimer's Disease with Plausible Molecular Initiating Event Plug-Ins for Environmental Neurotoxicants

The worldwide prevalence of sporadic (late-onset) Alzheimer's disease (sAD) is dramatically increasing. Aging and genetics are important risk factors, but systemic and environmental factors contribute to this risk in a still poorly understood way. Within the frame of BioMed21, the Adverse Outcome Pathway (AOP) concept for toxicology was recommended as a tool for enhancing human disease research and accelerating translation of data into human applications. Its potential to capture biological knowledge and to increase mechanistic understanding about human diseases has been substantiated since. In pursuit of the tau-cascade hypothesis, a tau-driven AOP blueprint toward the adverse outcome of memory loss is proposed. Sequences of key events and plausible key event relationships, triggered by the bidirectional relationship between brain cholesterol and glucose dysmetabolism, and contributing to memory loss are captured. To portray how environmental factors may contribute to sAD progression, information on chemicals and drugs, that experimentally or epidemiologically associate with the risk of AD and mechanistically link to sAD progression, are mapped on this AOP. The evidence suggests that chemicals may accelerate disease progression by plugging into sAD relevant processes. The proposed AOP is a simplified framework of key events and plausible key event relationships representing one specific aspect of sAD pathology, and an attempt to portray chemical interference. Other sAD-related AOPs (e.g., Aβ-driven AOP) and a better understanding of the impact of aging and genetic polymorphism are needed to further expand our mechanistic understanding of early AD pathology and the potential impact of environmental and systemic risk factors.

Nanodelivery of oxiracetam enhances memory, functional recovery and induces neuroprotection following concussive head injury

Military personnel are the most susceptible to concussive head injury (CHI) caused by explosion, blast or missile or blunt head trauma. Mild to moderate CHI could induce lifetime functional and cognitive disturbances causing significant decrease in quality of life. Severe CHI leads to instant death and lifetime paralysis. Thus, further exploration of novel therapeutic agents or new features of known pharmacological agents are needed to enhance quality of life of CHI victims. Previous reports from our laboratory showed that mild CHI induced by weight drop technique causing an impact of 0.224N results in profound progressive functional deficit, memory impairment and brain pathology from 5h after trauma that continued over several weeks of injury. In this investigation we report that TiO2 nanowired delivery of oxiracetam (50mg/kg, i.p.) daily for 5 days after CHI resulted in significant improvement of functional deficit on the 8th day. This was observed using Rota Rod treadmill, memory improvement assessed by the time spent in finding hidden platform under water. The motor function improvement is seen in oxiracetam treated CHI group by placing forepaw on an inclined mesh walking and foot print analysis for stride length and distance between hind feet. TiO2-nanowired oxiracetam also induced marked improvements in the cerebral blood flow, reduction in the BBB breakdown and edema formation as well as neuroprotection of neuronal, glial and myelin damages caused by CHI at light and electron microscopy on the 7th day after 5 days TiO2 oxiracetam treatment. Adverse biochemical events such as upregulation of CSF nitrite and nitrate, IL-6, TNF-a and p-Tau are also reduced significantly in oxiracetam treated CHI group. On the other hand post treatment of 100mg/kg dose of normal oxiracetam in identical conditions after CHI is needed to show slight but significant neuroprotection together with mild recovery of memory function and functional deficits on the 8th day. These observations are the first to point out that nanowired delivery of oxiracetam has superior neuroprotective ability in CHI. These results indicate a promising clinical future of TiO2 oxiracetam in treating CHI patients for better quality of life and neurorehabilitation, not reported earlier.

Pharmacological relevance of CDK inhibitors in Alzheimer's disease

Evidence suggests that cell cycle activation plays a role in the pathophysiology of neurodegenerative diseases. Alzheimer's disease is a progressive, terminal neurodegenerative disease that affects memory and other important mental functions. Intracellular deposition of Tau protein, a hyperphosphorylated form of a microtubule-associated protein, and extracellular aggregation of Amyloid β protein, which manifests as neurofibrillary tangles (NFT) and senile plaques, respectively, characterize this condition. In recent years, however, several studies have concluded that cell cycle re-entry is one of the key causes of neuronal death in the pathogenesis of Alzheimer's disease. The eukaryotic cell cycle is well-coordinated machinery that performs critical functions in cell replenishment, such as DNA replication, cell creation, repair, and the birth of new daughter cells from the mother cell. The complex interplay between the levels of various cyclins and cyclin-dependent kinases (CDKs) at different checkpoints is needed for cell cycle synchronization. CDKIs (cyclin-dependent kinase inhibitors) prevent cyclin degradation and CDK inactivation. Different external and internal factors regulate them differently, and they have different tissue expression and developmental functions. The checkpoints ensure that the previous step is completed correctly before starting the new cell cycle phase, and they protect against the transfer of defects to the daughter cells. Due to the development of more selective and potent ATP-competitive CDK inhibitors, CDK inhibitors appear to be on the verge of having a clinical impact. This avenue is likely to yield new and effective medicines for the treatment of cancer and other neurodegenerative diseases. These new methods for recognizing CDK inhibitors may be used to create non-ATP-competitive agents that target CDK4, CDK5, and other CDKs that have been recognized as important therapeutic targets in Alzheimer's disease treatment.

C1 Inhibits Liquid-Liquid Phase Separation and Oligomerization of Tau and Protects Neuroblastoma Cells against Toxic Tau Oligomers

The pathological aggregation of tau is one of the major contributing factors for several neurodegenerative tauopathies, including Alzheimer's disease. Here, we report that C1, a synthetic derivative of curcumin, strongly inhibited both the aggregation and filament formation of purified tau and protected neuroblastoma cells from the deleterious effects of the tau oligomers. Using confocal microscopy, C1 was found to reduce both the size and number of the tau droplets and increased the critical concentration of tau required for the droplet formation in vitro indicating that C1 suppressed the liquid-liquid phase separation of tau. C1 inhibited the aggregation of tau with a half-maximal inhibitory concentration of 1.5 ± 0.1 μM. An analysis of the aggregation kinetics data indicated that C1 strongly reduced the initial rate of the aggregation of tau. A dot blot analysis using tau-oligomer-specific antibody indicated that C1 inhibited the oligomerization of tau. Furthermore, dynamic light scattering experiments suggested that C1 strongly reduced the mean diameter of the tau oligomers. Atomic force microscopy experiments showed that C1 treatment reduced both the size and number of tau oligomers, suppressed the transition of tau oligomers into filaments, and also disintegrated preformed tau filaments. Also, the binding interaction of C1 with tau was monitored using absorbance and fluorescence spectroscopy. C1 bound to Y310W-tau with a dissociation constant of 2.0 ± 0.5 μM. The findings suggested that C1 is a potent inhibitor of tau aggregation and provided insights into the inhibitory mechanism of C1 on the oligomerization and fibril formation of tau.

Downregulation of glob1 suppresses pathogenesis of human neuronal tauopathies in Drosophila by regulating tau phosphorylation and ROS generation

Human tauopathies represent a group of neurodegenerative disorders, characterized by abnormal hyperphosphorylation and aggregation of tau protein, which ultimately cause neurodegeneration. The aberrant tau hyperphosphorylation is mostly attributed to the kinases/phosphatases imbalance, which is majorly contributed by the generation of reactive oxygen species (ROS). Globin(s) represent a well-conserved group of proteins which are involved in O₂ management, regulation of cellular ROS in different cell types. Similarly, Drosophila globin1 (a homologue of human globin) with its known roles in oxygen management and development of nervous system exhibits striking similarities with the mammalian neuroglobin. Several recent evidences support the hypothesis that neuroglobins are associated with Alzheimer's disease pathogenesis. We herein noted that targeted expression of human-tau induces the cellular level of Glob1 protein in Drosophila tauopathy models. Subsequently, RNAi mediated restored level of Glob1 restricts the pathogenic effect of human-tau by minimizing its hyperphosphorylation via GSK-3β/p-Akt and p-JNK pathways. In addition, it also activates the Nrf2-keap1-ARE cascade to stabilize the tau-mediated increased level of ROS. These two parallel cellular events provide a significant rescue against human tau-mediated neurotoxicity in the fly models. For the first time we report a direct involvement of an oxygen sensing globin gene in tau etiology. In view of the fact that human genome encodes for the multiple Globin proteins including a nervous system specific neuroglobin; and therefore, our findings may pave the way to investigate if the conserved oxygen sensing globin gene(s) can be exploited in devising novel therapeutic strategies against tauopathies.

Gene Expression Imputation Across Multiple Tissue Types Provides Insight Into the Genetic Architecture of Frontotemporal Dementia and Its Clinical Subtypes

BACKGROUND

The etiology of frontotemporal dementia (FTD) is poorly understood. To identify genes with predicted expression levels associated with FTD, we integrated summary statistics with external reference gene expression data using a transcriptome-wide association study approach.

METHODS

FUSION software was used to leverage FTD summary statistics (all FTD: n = 2154 cases, n = 4308 controls; behavioral variant FTD: n = 1337 cases, n = 2754 controls; semantic dementia: n = 308 cases, n = 616 controls; progressive nonfluent aphasia: n = 269 cases, n = 538 controls; FTD with motor neuron disease: n = 200 cases, n = 400 controls) from the International FTD-Genomics Consortium with 53 expression quantitative loci tissue type panels (n = 12,205; 5 consortia). Significance was assessed using a 5% false discovery rate threshold.

RESULTS

We identified 73 significant gene-tissue associations for FTD, representing 44 unique genes in 34 tissue types. Most significant findings were derived from dorsolateral prefrontal cortex splicing data (n = 19 genes, 26%). The 17q21.31 inversion locus contained 23 significant associations, representing 6 unique genes. Other top hits included SEC22B (a gene involved in vesicle trafficking), TRGV5, and ZNF302. A single gene finding (RAB38) was observed for behavioral variant FTD. For other clinical subtypes, no significant associations were observed.

CONCLUSIONS

We identified novel candidate genes (e.g., SEC22B) and previously reported risk regions (e.g., 17q21.31) for FTD. Most significant associations were observed in dorsolateral prefrontal cortex splicing data despite the modest sample size of this reference panel. This suggests that our findings are specific to FTD and are likely to be biologically relevant highlights of genes at different FTD risk loci that are contributing to the disease pathology.

Alpha-lipoic acid ameliorates tauopathy-induced oxidative stress, apoptosis, and behavioral deficits through the balance of DIAP1/DrICE ratio and redox homeostasis: Age is a determinant factor

Tauopathies belong to a heterogeneous class of neuronal diseases resulting in the metabolic disturbance. A disulfide natural compound of Alpha-Lipoic acid (ALA) has shown numerous pharmacologic, antioxidant, and neuroprotective activities under neuropathological conditions. The aim of this study was to investigate the neuroprotective effects of ALA on the tauopathy-induced oxidative disturbance and behavioral deficits. The transgenic Drosophila model of tauopathy induced by human tau^R406W using GAL4/UAS system and effects of ALA (0.001, 0.005, and 0.025 % w/w of diet) on the neuropathology of tau in younger (20 days) and older (30 days) adults were investigated via biochemical, molecular, behavioral and in-situ tissue analyses. Expression of apoptosis-related proteins involving Drosophila Cyt-c-d (trigger of intrinsic apoptosis) and DrICE (effector caspase) were upregulated in both ages (20 and 30 days) and DIAP1 (caspase inhibitor) has reduced only in older model flies compared to the controls. Remarkably, all doses of ALA increased DIAP1 and glutathione (GSH) as well as reducing Cyt-c-d and lipid peroxidation (LPO) in the younger flies compared to the model flies. Moreover, the higher doses of ALA were able to decrease thiol concentrations, to increase total antioxidant capacity, and to improve the behavioral deficits (locomotor function, olfactory memory, and ethanol sensitivity) in the younger flies. On the other hand, only a higher dose of ALA was able to decrease DrICE, Cyt-c-d, LPO, and thiol as well as increasing antioxidant capacity and decreasing ethanol sensitivity (ST50, RT50) in the older flies. TUNEL assay showed that all doses of ALA could potentially increase the DIAP1/DrICE ratio and exert anti-apoptotic effects on younger, but not on the older adults. Furthermore, data obtained from the in-situ ROS assay confirmed that only a higher dose of ALA significantly decreased the ROS level at both ages. Our data showed that an effective neuroprotective dose of ALA and its mechanism of action on this model of tauopathy could potentially be influenced by longevity. Moreover, it was shown that ALA prevents apoptosis and decreases the redox homeostasis, and this partially explains the mechanism by which ALA diminishes behavioral deficits.

Clinicopathological Relationships in an Aged Case of DOORS Syndrome With a p.Arg506X Mutation in the ATP6V1B2 Gene

DOORS [deafness, onychodystrophy, osteodystrophy, intellectual disability (mental retardation), and seizures] syndrome can be caused by mutations in the TBC1D24 and ATP6V1B2 genes, both of which are involved in endolysosomal function. Because of its extreme rarity, to date, no detailed neuropathological assessment has been performed to establish clinicopathological relationships and, thereby, understand better the neurobiology of this disease in aged cases. Accordingly, the aim of the current study was to highlight the clinicopathological characteristics of a novel case with a presumable de novo mutation in the ATP6V1B2 gene from a neuropathological point of view. This Caucasian male patient, who died at the age of 72 years, presented all the typical cardinal signs of DOORS syndrome. In addition, behavioral alterations, pyramidal signs, and Parkinsonism were observed. The p.R506X pathogenic mutation identified in the ATP6V1B2 gene was responsible for the clinical phenotype. The detailed neuropathological assessment revealed a limbic-predominant tauopathy in the forms of argyrophilic grain disease, primary age-related tauopathy, and age-related tau-astrogliopathy. In summary, we present the first detailed clinicopathological report of a patient with DOORS syndrome harboring a pathogenic mutation in the ATP6V1B2 gene. The demonstrated tauopathy may be considered as a consequence of lysosomal and/or mitochondrial dysfunction, similar to that found in Niemann-Pick type C disease, which is another lysosomal disorder characterized by premature neurodegenerative disorder.

Neuroprotection Against Oxidative Stress: Phytochemicals Targeting TrkB Signaling and the Nrf2-ARE Antioxidant System

Oxidative stress (OS) plays a critical role in the pathophysiology of several brain-related disorders, including neurodegenerative diseases and ischemic stroke, which are the major causes of dementia. The Nrf2-ARE (nuclear factor erythroid 2-related factor 2/antioxidant responsive element antioxidant) system, the primary cellular defense against OS, plays an essential role in neuroprotection by regulating the expressions of antioxidant molecules and enzymes. However, simultaneous events resulting in the overproduction of reactive oxygen species (ROS) and deregulation of the Nrf2-ARE system damage essential cell components and cause loss of neuron structural and functional integrity. On the other hand, TrkB (tropomyosin-related kinase B) signaling, a classical neurotrophin signaling pathway, regulates neuronal survival and synaptic plasticity, which play pivotal roles in memory and cognition. Also, TrkB signaling, specifically the TrkB/PI3K/Akt (TrkB/phosphatidylinositol 3 kinase/protein kinase B) pathway promotes the activation and nuclear translocation of Nrf2, and thus, confers neuroprotection against OS. However, the TrkB signaling pathway is also known to be downregulated in brain disorders due to lack of neurotrophin support. Therefore, activations of TrkB and the Nrf2-ARE signaling system offer a potential approach to the design of novel therapeutic agents for brain disorders. Here, we briefly overview the development of OS and the association between OS and the pathogenesis of neurodegenerative diseases and brain injury. We propose the cellular antioxidant defense and TrkB signaling-mediated cell survival systems be considered pharmacological targets for the treatment of neurodegenerative diseases, and review the literature on the neuroprotective effects of phytochemicals that can co-activate these neuronal defense systems.

Association between amphetamine-related disorders and dementia-a nationwide cohort study in Taiwan

Objective

We have conducted a study to clarify the association between amphetamine‐related disorders (ARD) and the risk of developing dementia.

Methods

This study used a retrospective cohort design by using Taiwan’s National Health Research Institute Database. A random sample of 68,300 subjects between January 1, 2000, and December 31, 2015, was obtained, comprising of 17,075 patients with ARD, and 51,225 controls without ARD (1:3), matched for gender and age group. After adjusting for covariates, a Fine and Gray’s survival analysis (competing with mortality) was used to compare the risk of dementia during a 15‐year follow‐up period.

Results

In the present study, 1,751 of 17,075 patients with ARD and 2,147 of 51,225 in the control group without ARD (883.10 vs 342.83 per 100,000 person‐years) developed dementia. ARD cohort was more likely to develop dementia (hazard ratio = 4.936 [95% CI: 4.609–5.285, P < 0.001). After adjusting for gender, age groups, education, monthly insured premiums, urbanization level, geographic region, comorbidities, the hazard ratio for ARD patients was 5.034 (95% CI: 4.701–5.391, P < 0.001). ARD has been associated with overall dementia, Alzheimer dementia, vascular dementia, and other dementia. Both the amphetamine use disorder and amphetamine‐induced psychotic disorders were associated with the risk of overall dementia, Alzheimer dementia, vascular dementia, and other dementia.

Interpretation

This study shows that patients with ARD, both the amphetamine use disorder and the amphetamine‐induced psychotic disorder, may have a nearly fivefold risk of developing dementia, including Alzheimer dementia and other types of dementia.