Mitochondrial Oxidative and Nitrosative Stress and Alzheimer Disease

Sex-specific mechanisms of cerebral microvascular BKCa dysfunction in a mouse model of Alzheimer's disease

INTRODUCTION

Cerebrovascular dysfunction occurs in Alzheimer's disease (AD), impairing hemodynamic regulation. Large conductance Ca2+-activated K+ channels (BKCa) regulate cerebrovascular reactivity and are impaired in AD. BKCa activity depends on intracellular Ca2+ (Ca2+ sparks) and nitro-oxidative post-translational modifications. However, whether these mechanisms underlie BKCa impairment in AD remains unknown.

METHODS

Cerebral arteries from 5x-FAD and wild-type (WT) littermates were used for molecular biology, electrophysiology, ex vivo, and in vivo experiments.

RESULTS

Arterial BKCa activity is reduced in 5x-FAD via sex-dependent mechanisms: in males, there is lower BKα subunit expression and less Ca2+ sparks. In females, we observed reversible nitro-oxidative modification of BKCa. Further, BKCa is involved in hemodynamic regulation in WT mice, and its dysfunction is associated with vascular deficits in 5x-FAD.

DISCUSSION

Our data highlight the central role played by BKCa in cerebral hemodynamic regulation and that molecular mechanisms of its impairment diverge based on sex in 5x-FAD.

HIGHLIGHTS

Cerebral microvascular BKCa dysfunction occurs in both female and male 5x-FAD. Reduction in BKα subunit protein and Ca2+ sparks drive the dysfunction in males. Nitro-oxidative stress is present in females, but not males, 5x-FAD. Reversible nitro-oxidation of BKα underlies BKCa dysfunction in female 5x-FAD.

Advancements in mitochondrial-targeted nanotherapeutics: overcoming biological obstacles and optimizing drug delivery

In recent decades, nanotechnology has significantly advanced drug delivery systems, particularly in targeting subcellular organelles, thus opening new avenues for disease treatment. Mitochondria, critical for cellular energy and health, when dysfunctional, contribute to cancer, neurodegenerative diseases, and metabolic disorders. This has propelled the development of nanomedicines aimed at precise mitochondrial targeting to modulate their function, marking a research hotspot. This review delves into the recent advancements in mitochondrial-targeted nanotherapeutics, with a comprehensive focus on targeting strategies, nanocarrier designs, and their therapeutic applications. It emphasizes nanotechnology's role in enhancing drug delivery by overcoming biological barriers and optimizing drug design for specific mitochondrial targeting. Strategies exploiting mitochondrial membrane potential differences and specific targeting ligands improve the delivery and mitochondrial accumulation of nanomedicines. The use of diverse nanocarriers, including liposomes, polymer nanoparticles, and inorganic nanoparticles, tailored for effective mitochondrial targeting, shows promise in anti-tumor and neurodegenerative treatments. The review addresses the challenges and future directions in mitochondrial targeting nanotherapy, highlighting the need for precision, reduced toxicity, and clinical validation. Mitochondrial targeting nanotherapy stands at the forefront of therapeutic strategies, offering innovative treatment perspectives. Ongoing innovation and research are crucial for developing more precise and effective treatment modalities.

PET Imaging with [18F]ROStrace Detects Oxidative Stress and Predicts Parkinson's Disease Progression in Mice

Although the precise molecular mechanisms responsible for neuronal death and motor dysfunction in late-onset Parkinson's disease (PD) are unknown, evidence suggests that mitochondrial dysfunction and neuroinflammation occur early, leading to a collective increase in reactive oxygen species (ROS) production and oxidative stress. However, the lack of methods for tracking oxidative stress in the living brain has precluded its use as a potential biomarker. The goal of the current study is to address this need through the evaluation of the first superoxide (O2•-)-sensitive radioactive tracer, [18F]ROStrace, in a model of late-onset PD. To achieve this goal, MitoPark mice with a dopaminergic (DA) neuron-specific deletion of transcription factor A mitochondrial (Tfam) were imaged with [18F]ROStrace from the prodromal phase to the end-stage of PD-like disease. Our data demonstrate [18F]ROStrace was sensitive to increased oxidative stress during the early stages of PD-like pathology in MitoPark mice, which persisted throughout the disease course. Similarly to PD patients, MitoPark males had the most severe parkinsonian symptoms and metabolic impairment. [18F]ROStrace retention was also highest in MitoPark males, suggesting oxidative stress as a potential mechanism underlying the male sex bias of PD. Furthermore, [18F]ROStrace may provide a method to identify patients at risk of Parkinson's before irreparable neurodegeneration occurs and enhance clinical trial design by identifying patients most likely to benefit from antioxidant therapies.

Functional Relationships between L1CAM, LC3, ATG12, and Aβ

Abnormal protein accumulations in the brain are linked to aging and the pathogenesis of dementia of various types, including Alzheimer's disease. These accumulations can be reduced by cell indigenous mechanisms. Among these is autophagy, whereby proteins are transferred to lysosomes for degradation. Autophagic dysfunction hampers the elimination of pathogenic protein aggregations that contribute to cell death. We had observed that the adhesion molecule L1 interacts with microtubule-associated protein 1 light-chain 3 (LC3), which is needed for autophagy substrate selection. L1 increases cell survival in an LC3-dependent manner via its extracellular LC3 interacting region (LIR). L1 also interacts with Aβ and reduces the Aβ plaque load in an AD model mouse. Based on these results, we investigated whether L1 could contribute to autophagy of aggregated Aβ and its clearance. We here show that L1 interacts with autophagy-related protein 12 (ATG12) via its LIR domain, whereas interaction with ubiquitin-binding protein p62/SQSTM1 does not depend on LIR. Aβ, bound to L1, is carried to the autophagosome leading to Aβ elimination. Showing that the mitophagy-related L1-70 fragment is ubiquitinated, we expect that the p62/SQSTM1 pathway also contributes to Aβ elimination. We propose that enhancing L1 functions may contribute to therapy in humans.

Bu zhong Yiqi Decoction ameliorates mild cognitive impairment by improving mitochondrial oxidative stress damage via the SIRT3/MnSOD/OGG1 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Bu-Zhong-Yi-Qi Decoction(BZYQD) is a traditional formula commonly used in China, known for its effects in tonifying Qi and raising Yang. It can relieve symptoms of cognitive impairment such as forgetfulness and lack of concentration caused by qi deficiency, which is common in aging and debilitating. However, much of the current research on BZYQD has been focused on its impact on the digestive system, leaving its molecular mechanisms in improving cognitive function largely unexplored.

AIM OF THE STUDY

Cognitive decline in the aging central nervous system is intrinsically linked to oxidative damage. This study aims to investigate the therapeutic mechanism of BZYQD in treating mild cognitive impairment caused by qi deficiency, particularly through repair of mitochondrial oxidative damage.

MATERIALS AND METHODS

A rat model of mild cognitive impairment (MCI) was established by administering reserpine subcutaneously for two weeks, followed by a two-week treatment with BZYQD/GBE. In vitro experiments were conducted to assess the effects of BZYQD on neuronal cells using a H2O2-induced oxidative damage model in PC12 cells. The open field test and the Morris water maze test evaluated the cognitive and learning memory abilities of the rats. HE staining and TEM were employed to observe morphological changes in the hippocampus and its mitochondria. Mitochondrial activity, ATP levels, and cellular viability were measured using assay kits. Protein expression in the SIRT3/MnSOD/OGG1 pathway was analyzed in tissues and cells through western blotting. Levels of 8-OH-dG in mitochondria extracted from tissues and cells were quantified using ELISA. Mitochondrial morphology in PC12 cells was visualized using Mito Red, and mitochondrial membrane potential was assessed using the JC-1 kit.

RESULTS

BZYQD treatment significantly improved cognitive decline caused by reserpine in rats, as well as enhanced mitochondrial morphology and function in the hippocampus. Our findings indicate that BZYQD mitigates mtDNA oxidative damage in rats by modulating the SIRT3/MnSOD/OGG1 pathway. In PC12 cells, BZYQD reduced oxidative damage to mitochondria and mtDNA in H2O2-induced conditions and was associated with changes in the SIRT3/MnSOD/OGG1 pathway.

CONCLUSION

BZYQD effectively counteracts reserpine-induced mild cognitive impairment and ameliorates mitochondrial oxidative stress damage through the SIRT3/MnSOD/OGG1 pathway.

Effects of β-sitosterol on anxiety in migraine-induced rats: The role of oxidative/nitrosative stress and mitochondrial function

AIMS

Anxiety often coexists with migraine, and both conditions share a commonality in oxidative/nitrosative stress and mitochondrial dysfunction contributing to their pathogenesis. β-Sitosterol, a plant sterol, has shown promise in mitigating oxidative/nitrosative stress, enhancing mitochondrial function, and exerting neuroprotective effects. In this study, we investigated the impact of β-sitosterol on migraine-associated anxiety and whether this effect was associated with alleviation of oxidative/nitrosative stress and improvement in mitochondrial function.

METHODS

Nitroglycerin was used to induce migraine in adult male Wistar rats. β-Sitosterol treatment consisted of daily intraperitoneal injections (10 mg/kg) for 10 days following migraine induction. Anxiety levels were evaluated using open-field test (OFT) and hole-board test (HBT). Frontal cortex samples were analyzed for malondialdehyde (MDA), glutathione (GSH), reactive oxygen/nitrogen species, nitric oxide (NO) (markers of oxidative/nitrosative stress), and ATP (indicator of mitochondrial function).

RESULTS

Migraine induction led to impaired performance in both the OFT and the HBT. Concurrently, it elevated MDA, reactive oxygen/nitrogen species, and NO levels while diminishing GSH levels in the frontal cortex, signifying heightened oxidative/nitrosative stress. Moreover, ATP levels decreased, indicating mitochondrial dysfunction. Treatment with β-sitosterol significantly restored performance in both behavioral assays and normalized the levels of MDA, GSH, reactive oxygen/nitrogen species, NO, and ATP.

CONCLUSION

β-Sitosterol exerted anxiolytic effects in migraine, which can be attributed to its ability to ameliorate oxidative/nitrosative stress and enhance mitochondrial function.

Leveraging the redundancy of S-denitrosylases in response to S-nitrosylation of caspases: Experimental strategies and beyond

Redox-based protein posttranslational modifications, such as S-nitrosylation of critical, active site cysteine thiols have garnered significant clinical attention and research interest, reasoning for one of the crucial biological implications of reactive messenger molecule, nitric oxide in the cellular repertoire. The stringency of the S-(de)nitrosylation-based redox switch governs the activity and contribution of several susceptible enzymes in signal transduction processes and diverse pathophysiological settings, thus establishing it as a transient yet reasonable, and regulated mechanism of NO adduction and release. Notably, endogenous proteases like cytosolic and mitochondrial caspases with a molecular weight ranging from 33 to 55 kDa are susceptible to performing this biochemistry in the presence of major oxidoreductases, which further unveils the enormous redox-mediated regulational control of caspases in the etiology of diseases. In addition to advancing the progress of the current state of understanding of 'redox biochemistry' in the field of medicine and enriching the existing dynamic S-nitrosoproteome, this review stands as a testament to an unprecedented shift in the underpinnings for redundancy and redox relay between the major redoxin/antioxidant systems, fine-tuning of which can command the apoptotic control of caspases at the face of nitro-oxidative stress. These intricate functional overlaps and cellular backups, supported rationally by kinetically favorable reaction mechanisms suggest the physiological relevance of identifying and involving such cognate substrates for cellular S-denitrosylases that can shed light on the bigger picture of extensively proposing targeted therapies and redox-based drug designing to potentially alleviate the side effects of NOx/ROS in disease pathogenesis.

Are high copper levels related to Alzheimer's and Parkinson's diseases? A systematic review and meta-analysis of articles published between 2011 and 2022

Copper performs an important role in the brain, but in high levels it can be neurotoxic. Further, some authors have described that copper dyshomeostasis could be related with neurodegenerative diseases. Thus, this review was performed to observe whether high copper levels are related to Alzheimer's and Parkinson's diseases (AD and PD), using the literature published recently. Articles that measured copper levels in AD or PD patients was included, as well as they that measured copper levels in models used to mimic these diseases. Also, results about high copper levels effects and its relationship with AD and PD observed in laboratory animals are considered. In summary, 38 and 24 articles with AD and PD patients were included, respectively. Despite of the heterogeneity between the studies in humans, meta-analysis has demonstrated that there is an increase in free and total copper levels in the blood of AD patients compared to controls, and a decrease in copper levels in PD patients. A decrease in the metal content in postmortem brain tissue was observed in AD and PD. In manuscripts using animal models that mimic AD and PD, it was included seven and three articles, respectively. Two of them have reported an increase in copper concentrations in AD model, and one in PD model. Finally, studies with laboratory animals have concluded that high copper levels are related to oxidative stress, neuroinflammation, mitochondrial dysfunction, changes in neurotransmitter levels, cell death, and reduced both cognitive and locomotor activity, which are also described in AD or PD.

Recent progress and applications of small molecule inhibitors of Keap1-Nrf2 axis for neurodegenerative diseases

The Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway serves as a crucial regulator against oxidative stress (OS) damage in various cells and organs. It has garnered significant attention as a potential therapeutic target for neurodegenerative diseases (NDD). Although progress has been achieved in strategies to regulate the Keap1-Nrf2 pathway, the availability of Nrf2 activators applicable to NDD is currently limited. Currently, the FDA has approved the Nrf2 activators dimethyl fumarate (DMF) and Omaveloxolone (Omav) as novel first-line oral drugs for the treatment of patients with relapsing forms of multiple sclerosis and Friedreich's ataxia. A promising alternative approach involves the direct inhibition of Keap1-Nrf2 protein-protein interactions (PPI), which offers numerous advantages over the use of electrophilic Nrf2 activators, primarily in avoiding off-target effects. This review examines the compelling evidence supporting the beneficial role of Nrf2 in NDD and explores the potential of Keap1 inhibitors and Keap1-Nrf2 PPI inhibitors as therapeutic agents, with the aim to provide further insights into the development of inhibitors targeting this pathway for the treatment of NDD.

Role of Thioredoxin System in Regulating Cellular Redox Status in Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia and a public health problem. It exhibits significant oxidative stress and redox alterations. The antioxidant enzyme systems defend the cellular environment from oxidative stress. One of the redox systems is the thioredoxin system (TS), which exerts decisive control over the cellular redox environment. We aimed to review the protective effects of TS, which include thioredoxin (Trx), thioredoxin reductase (TrxR), and NADPH. In the following, we discussed the physiological functioning and the role of the TS in maintaining the cellular redox-homeostasis in the AD-damaged brain. Trx protects the cellular environment from oxidative stress, while TrxR is crucial for the cellular detoxification of reactive oxygen species in the brain. However, TS dysregulation increases the susceptibility to cellular death. The changes in Trx and TrxR levels are significantly associated with AD progression. Though the data from human, animal, and cellular models support the neuroprotective role of TS in the brain of AD patients, the translational potential of these findings to clinical settings is not yet applied. This review summarizes the current knowledge on the emerging role of the TrxR-Trx system in AD.

Oxidative damage in neurodegeneration: roles in the pathogenesis and progression of Alzheimer disease

Alzheimer disease (AD) is associated with multiple etiologies and pathological mechanisms, among which oxidative stress (OS) appears as a major determinant. Intriguingly, OS arises in various pathways regulating brain functions, and it seems to link different hypotheses and mechanisms of AD neuropathology with high fidelity. The brain is particularly vulnerable to oxidative damage, mainly because of its unique lipid composition, resulting in an amplified cascade of redox reactions that target several cellular components/functions ultimately leading to neurodegeneration. The present review highlights the "OS hypothesis of AD," including amyloid beta-peptide-associated mechanisms, the role of lipid and protein oxidation unraveled by redox proteomics, and the antioxidant strategies that have been investigated to modulate the progression of AD. Collected studies from our groups and others have contributed to unraveling the close relationships between perturbation of redox homeostasis in the brain and AD neuropathology by elucidating redox-regulated events potentially involved in both the pathogenesis and progression of AD. However, the complexity of AD pathological mechanisms requires an in-depth understanding of several major intracellular pathways affecting redox homeostasis and relevant for brain functions. This understanding is crucial to developing pharmacological strategies targeting OS-mediated toxicity that may potentially contribute to slow AD progression as well as improve the quality of life of persons with this severe dementing disorder.

The increment of annexin V-positive microvesicles versus annexin V-negative microvesicles in CSF of an animal model of Alzheimer's disease

OBJECTIVE

Extracellular microvesicles (MVs) as a specific signaling molecule have received much attention in nervous system studies. Alterations in the tissue redox status in pathological conditions, such as Alzheimer's disease (AD), facilitate the translocation of cell membrane phosphatidylserine to the outer leaflet and lead to the MVs shedding. Annexin V binds with high affinity to phosphatidylserine. Some arguments exist about whether Annexin V-negative MVs should be considered in pathological conditions.

MATERIAL AND METHOD

We compared the kinetics of two phenotypes of Annexin V-positive and Annexin V-negative MVs in the cerebrospinal fluid (CSF) of amyloid-β (Aβ)-treated male Wistar rats with flow cytometry technique. The Aβ was injected bilaterally into the cerebral ventricles. Thioflavin T staining was used to confirm the presence of hippocampal Aβ fibrils two weeks post-Aβ injection. Levels of hippocampal interleukin-1β were assessed as an inflammatory index. The CSF malondialdehyde (MDA) concentration was determined. The cognitive impairment and anxiety behaviors were assessed by object recognition and elevated plus maze tests, respectively.

RESULTS

Elevation of MDA levels and a significant rise in the scoring of IL-1β staining were found in the Aβ group. The Aβ induced anxiogenic behavior, impaired novel object recognition memory, and increased the CSF levels of the total number of MVs. The number of Annexin V-positive MVs was significantly higher than Annexin V-negative MVs in all groups.

CONCLUSION

Data showed that Annexin V-positive MVs potentially have a significant contribution to the pathophysiology of the Aβ-induced cognitive impairment. To catch a clear image of microvesicle production in pathological conditions, both phenotypes of Annexin V-positive and Annexin V-negative MVs should be analyzed and reported.

A Novel NOX Inhibitor Alleviates Parkinson's Disease Pathology in PFF-Injected Mice

Oxidative stress-mediated damage is often a downstream result of Parkinson's disease (PD), which is marked by sharp decline in dopaminergic neurons within the nigrostriatal regions of the brain, accounting for the symptomatic motor deficits in patients. Regulating the level of oxidative stress may present a beneficial approach in preventing PD pathology. Here, we assessed the efficacy of a nicotinamide adenine phosphate (NADPH) oxidase (NOX) inhibitor, an exogenous reactive oxygen species (ROS) regulator synthesized by Aptabio therapeutics with the specificity to NOX-1, 2 and 4. Utilizing N27 rat dopaminergic cells and C57Bl/6 mice, we confirmed that the exposures of alpha-synuclein preformed fibrils (PFF) induced protein aggregation, a hallmark in PD pathology. In vitro assessment of the novel compound revealed an increase in cell viability and decreases in cytotoxicity, ROS, and protein aggregation (Thioflavin-T stain) against PFF exposure at the optimal concentration of 10 nM. Concomitantly, the oral treatment alleviated motor-deficits in behavioral tests, such as hindlimb clasping, rotarod, pole, nesting and grooming test, via reducing protein aggregation, based on rescued dopaminergic neuronal loss. The suppression of NOX-1, 2 and 4 within the striatum and ventral midbrain regions including Substantia Nigra compacta (SNc) contributed to neuroprotective/recovery effects, making it a potential therapeutic option for PD.

Pomegranate: A Source of Multifunctional Bioactive Compounds Potentially Beneficial in Alzheimer's Disease

Pomegranate fruit (PF) is a fruit rich in nutraceuticals. Nonedible parts of the fruit, especially peels, contain high amounts of bioactive components that have been largely used in traditional medicine, such as the Chinese, Unani, and Ayurvedic ones, for treating several diseases. Polyphenols such as anthocyanins, tannins, flavonoids, phenolic acids, and lignans are the major bioactive molecules present in PF. Therefore, PF is considered a source of natural multifunctional agents that exert simultaneously antioxidant, anti-inflammatory, antitumor, antidiabetic, cardiovascular, and neuroprotective activities. Recently, several studies have reported that the nutraceuticals contained in PF (seed, peel, and juice) have a potential beneficial role in Alzheimer's disease (AD). Research suggests that the neuroprotective effect of PF is mostly due to its potent antioxidant and anti-inflammatory activities which contribute to attenuate the neuroinflammation associated with AD. Despite the numerous works conducted on PF, to date the mechanism by which PF acts in combatting AD is not completely known. Here, we summarize all the recent findings (in vitro and in vivo studies) related to the positive effects that PF and its bioactive components can have in the neurodegeneration processes occurring during AD. Moreover, considering the high biotransformation characteristics of the nutraceuticals present in PF, we propose to consider the chemical structure of its active metabolites as a source of inspiration to design new molecules with the same beneficial effects but less prone to be affected by the metabolic degradation process.

Morus alba fruit diet ameliorates cognitive deficit in mouse model of streptozotocin-induced memory impairment

Mounting evidence shows that dietary intake of fruits with polyphenols is beneficial to improve impaired memory functions. This study explored the preventive as well as therapeutic effects of diet enriched with Morus alba fruits extract (DEMA) in streptozotocin (STZ) induced mouse model of memory impairment. The study consisted of two facets: one aspect consisted of pretreatment of animals with DEMA for two weeks followed by STZ (i.c.v) intervention and the second phase involved induction of dementia with STZ (i.c.v) followed by treatment with DEMA for 14 days. Cognitive functions of animals were measured by Morris Water Maze test and to delineate the associated mechanism of action, brain biochemical estimations (acetyl-cholinesterase activity, myeloperoxidase activity, thiobarbituric acid reactive species, superoxide dismutase activity, reduced glutathione and nitrite/nitrate) and histopathological studies (haematoxylin and eosin staining) were performed. Pre- and post- treatment with DEMA significantly prevented and attenuated, respectively, the detrimental effects of STZ on mice brain. The results demonstrated that dietary modification, by incorporation of M. alba fruits, reduces the incidence and aids in treatment of memory disorder in mice by reducing central cholinergic activity, decreasing oxidative stress and preventing neurodegeneration.

Oxidative Stress in Brain in Amnestic Mild Cognitive Impairment

Amnestic mild cognitive impairment (MCI), arguably the earliest clinical stage of Alzheimer disease (AD), is characterized by normal activities of daily living but with memory issues but no dementia. Oxidative stress, with consequent damaged key proteins and lipids, are prominent even in this early state of AD. This review article outlines oxidative stress in MCI and how this can account for neuronal loss and potential therapeutic strategies to slow progression to AD.

Isolated Mitochondrial Preparations and In organello Assays: A Powerful and Relevant Ex vivo Tool for Assessment of Brain (Patho)physiology

Mitochondria regulate multiple aspects of neuronal development, physiology, plasticity, and pathology through their regulatory roles in bioenergetic, calcium, redox, and cell survival/death signalling. While several reviews have addressed these different aspects, a comprehensive discussion focussing on the relevance of isolated brain mitochondria and their utilities in neuroscience research has been lacking. This is relevant because the employment of isolated mitochondria rather than their in situ functional evaluation, offers definitive evidence of organelle-specificity, negating the interference from extra mitochondrial cellular factors/signals. This mini-review was designed primarily to explore the commonly employed in organello analytical assays for the assessment of mitochondrial physiology and its dysfunction, with a particular focus on neuroscience research. The authors briefly discuss the methodologies for biochemical isolation of mitochondria, their quality assessment, and cryopreservation. Further, the review attempts to accumulate the key biochemical protocols for in organello assessment of a multitude of mitochondrial functions critical for neurophysiology, including assays for bioenergetic activity, calcium and redox homeostasis, and mitochondrial protein translation. The purpose of this review is not to examine each and every method or study related to the functional assessment of isolated brain mitochondria, but rather to assemble the commonly used protocols of in organello mitochondrial research in a single publication. The hope is that this review will provide a suitable platform aiding neuroscientists to choose and apply the required protocols and tools to address their particular mechanistic, diagnostic, or therapeutic question dealing within the confines of the research area of mitochondrial patho-physiology in the neuronal perspective.

Nitric oxide synthase activity: A novel potential biomarker for predicting Alopecia areata

BACKGROUND

Alopecia areata is a dermatological disease characterized by nonscarring type hair loss. The cause of Alopecia areata not known exactly but studies support that it has an autoimmune etiology in which oxidative stress play an important role.

AIM

This study was conducted to evaluate the level of nitrosative stress in Alopecia areata and to investigate the predictive power of nitrosative stress parameters for Alopecia areata.

PATIENTS/METHODS

Thirty patients diagnosed with Alopecia areata, and 30 healthy controls were included in a prospective, cross-sectional study. In both groups, nitric oxide (NO^· ), peroxynitrite (ONOO^- ), and nitric oxide synthase (NOS) activity as nitrosative stress markers were measured spectrophotometrically in serum samples. The predictive power of nitrosative stress parameters in Alopecia areata and control groups was compared with binary logistic regression and Receiver Operating Characteristic analysis.

RESULTS

NO^· , ONOO^- , and NOS activity were significantly higher in patients with Alopecia areata than in the control group (p = 0.001; p < 0.001; p < 0.001, respectively). A positive correlation was found between the parameters. Significantly, binary logistic regression modeling suggested that increases in NOS (p = 0.003, OR = 1.305, 95% CI = 1.095-1.556) activity were associated with Alopecia areata.

CONCLUSION

According to the data obtained from the present study, patients with Alopecia areata were exposed to potent nitrosative stress. In particular, peroxynitrite, which acts as a bridge between reactive oxygen species and reactive nitrogen species, caused the expansion of the oxidative stress cascade. Nitrosative stress might play a role in the etiopathogenesis of Alopecia areata. Nitrosative stress parameters, particularly NOS activity, may be potential markers for Alopecia areata.

Characteristics of culture-condition stimulated exosomes or their loaded hydrogels in comparison with other extracellular vesicles or MSC lysates

Recently, it has become popular to study the use of extracellular vesicles (EVs) secreted by stem cells to repair damaged tissues or lost cells. Various cell types and physiological fluids release EVs, and they play an important role in cell-to-cell communication. Moreover, EVs have been implicated in important processes, such as immune responses, homeostasis maintenance, coagulation, inflammation, cancer progression, angiogenesis, and antigen presentation. Thus, EVs participate in both physiological and pathological progression. The main classes of EVs include exosomes, microvesicles (MVs), and apoptotic bodies (ApoBDs). Exosomes, which carry a mass of signal molecules such as RNA, DNA, proteins, and lipids, are the most important of these EVs subsets. Currently, exosomes are generating substantial interest in the scientific community. Exosomes loaded hydrogels or under different cultural environments exhibit different properties and functions. Therefore, the exosomes obtained from different sources and conditions are worth reviewing. More importantly, no review article has compared the different EVs, such as exosomes, MVs, ApoBDs, and mesenchymal stem cell (MSC) lysates, which are special soluble substances. The differentiation between EVs and MSC lysates is a logical approach. Accordingly, this review provides an update on the latest progress in studying the roles of culture-condition stimulated exosomes or their loaded hydrogels and the differentiation between exosomes, MVs, ApoBDs, and MSC lysates. Published studies were retrieved from the PubMed® database for review.

Neuroprotective and Antioxidant Role of Oxotremorine-M, a Non-selective Muscarinic Acetylcholine Receptors Agonist, in a Cellular Model of Alzheimer Disease

Alzheimer disease (AD) is a multifactorial and age-dependent neurodegenerative disorder, whose pathogenesis, classically associated with the formation of senile plaques and neurofibrillary tangles, is also dependent on oxidative stress and neuroinflammation chronicization. Currently, the standard symptomatic therapy, based on acetylcholinesterase inhibitors, showed a limited therapeutic potential, whereas disease-modifying treatment strategies are still under extensive research. Previous studies have demonstrated that Oxotremorine-M (Oxo), a non-selective muscarinic acetylcholine receptors agonist, exerts neurotrophic functions in primary neurons, and modulates oxidative stress and neuroinflammation phenomena in rat brain. In the light of these findings, in this study, we aimed to investigate the neuroprotective effects of Oxo treatment in an in vitro model of AD, represented by differentiated SH-SY5Y neuroblastoma cells exposed to Aβ_1-42 peptide. The results demonstrated that Oxo treatment enhances cell survival, increases neurite length, and counteracts DNA fragmentation induced by Aβ_1-42 peptide. The same treatment was also able to block oxidative stress and mitochondria morphological/functional impairment associated with Aβ_1-42 cell exposure. Overall, these results suggest that Oxo, by modulating cholinergic neurotransmission, survival, oxidative stress response, and mitochondria functionality, may represent a novel multi-target drug able to achieve a therapeutic synergy in AD. Illustration of the main pathological hallmarks and mechanisms underlying AD pathogenesis, including neurodegeneration and oxidative stress, efficiently counteracted by treatment with Oxo, which may represent a promising therapeutic molecule. Created with BioRender.com under academic license.

AlCl3 induced learning and memory deficit in zebrafish

Aluminium is a metal known to cause neurotoxicity in the brain, by promoting neurodegeneration and affecting memory and cognitive ability. AlCl₃ has been reported to enhance reactive oxygen species (ROS) and inflammatory markers which are further responsible for the degeneration of neurons. AlCl₃ exposure to zebrafish causes behavioral, biochemical, and neurochemical changes in the brain. In our study, Zebrafish were exposed to AlCl₃ at three different doses (50 µg/L, 100 µg/L, and 200 µg/L) for four consecutive days. On days 1st and 4th, a novel diving test was performed to check anxiety in zebrafish. T - maze and novel object recognition test were used to check the memory on days 3rd and 4th with the help of ANY-maze software. On the last day (4th day), zebrafishes were sacrificed and whole brains were used to perform the biochemical, neurotransmitters, histopathological, and immunohistochemistry analysis. Our study revealed that AlCl₃ exposure significantly decreased the total distance traveled, and the number of entries in the top zone and increased the time spent in the bottom zone, checked through the novel diving test. In the T maze test, AlCl₃ treated zebrafish showed significantly increased transfer latency to the favorable zone and time spent, and the number of entries to the unfavorable zone. The exploration time with the novel object was reduced significantly after AlCl₃ treatment. Moreover, reduced glutathione (GSH) and superoxide dismutase (SOD) levels were significantly reduced in AlCl₃ treated zebrafish whereas malondialdehyde (MDA) level was found to be increased, indicating high oxidative stress. The neurotransmitters level was also disturbed indicated by the significantly decreased GABA, dopamine, noradrenaline, and Serotonin levels and increased glutamate level in the brain of zebrafish treated with AlCl₃. Moreover, histopathological and immunohistochemistry study shows a markedly increased number of pyknotic neurons and reduced the expression of Nrf2 in the zebrafish brain after AlCl₃ exposure. These findings suggest that AlCl₃ significantly causes behavioral, biochemical, neurotransmitters, morphological, and molecular changes in zebrafish, ultimately causing AD.

Effect of cadmium administration on the antioxidant system and neuronal death in the hippocampus of rats

Cadmium (Cd) is a heavy metal classified as a carcinogen whose exposure could affect the function of the central nervous system. Studies suggest that Cd modifies neuronal morphology in the hippocampus and affects cognitive tasks. The oxidative stress pathway is proposed as a mechanism of toxicity. However, this mechanism is not precise yet. This study aimed to evaluate the effect of Cd administration on oxidative stress markers in the male rat's hippocampus. Male Wistar rats were divided into (1) control (drinking water) and (2) treatment with Cd (32.5 ppm of cadmium chloride (CdCl₂ ) in water). The Cd was administered for 2, 3, and 4 months. The results show that the oral administration of CdCl₂ increased the concentration of Cd in plasma and hippocampus, and this response is time-dependent on its administration. Likewise, it caused an increase in lipid peroxidation and nitrosative stress markers. Moreover, it increased reactive astrogliosis and antioxidant enzyme activity. Consequently, the progression of the oxidative response exacerbated neurodegeneration in hippocampal cells. Our results suggest that Cd exposure induces a severe oxidative response that contributes critically to hippocampal neurodegeneration. It is suggested that exposure to Cd increases the risk of developing neurological diseases, which contributes to a decrease in the quality of life of the human and the environment in which it lives.

Altered Metabolism in Alzheimer Disease Brain: Role of Oxidative Stress

Significance: Alzheimer disease (AD) is an all-too-common condition in the aging population. However, aging does not automatically equal neurodegeneration and memory decline. Recent Advances: This review article involves metabolic changes in the AD brain that are related to oxidative stress. Selected pathways are identified as potential targets for intervention in AD. Critical Issues: One of the main factors of AD is the oxidative imbalance within the central nervous system, causing a disruption in metabolic processes. Reactive oxygen species (ROS) are a natural consequence of many cellular processes, especially those associated with mitochondria, such as the electron transport chain. Some ROS, when kept under control and maintained at reasonable levels, often play roles in cell signaling. The cellular damage of ROS arises when oxidative imbalance occurs, in which case ROS are not controlled, leading to a myriad of alterations in cellular metabolic processes. These altered pathways include, among others, dysfunctional glycolysis, calcium regulation, lipid metabolism, mitochondrial processes, and mammalian target of rapamycin pathway dysregulation. Future Directions: Understanding how ROS can lead to these alterations can, ideally, elucidate therapeutic options for retarding AD progression in the aging population. Antioxid. Redox Signal. 36, 1289-1305.

Multi-target neuroprotective effects of herbal medicines for Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease is the most common form of dementia, but its treatment options remain few and ineffective. To find new therapeutic strategies, natural products have gained interest due to their neuroprotective potential, being able to target different pathological hallmarks associated with this disorder. Several plant species are traditionally used due to their empirical neuroprotective effects and it is worth to explore their mechanism of action.

AIM OF THE STUDY

This study intended to explore the neuroprotective potential of seven traditional medicinal plants, namely Scutellaria baicalensis, Ginkgo biloba, Hypericum perforatum, Curcuma longa, Lavandula angustifolia, Trigonella foenum-graecum and Rosmarinus officinalis. The safety assessment with reference to pesticides residues was also aimed.

MATERIALS AND METHODS

Decoctions prepared from these species were chemically characterized by HPLC-DAD and screened for their ability to scavenge four different free radicals (DPPH^•, ABTS^•+, O₂^•‒ and ^•NO) and to inhibit enzymes related to neurodegeneration (cholinesterases and glycogen synthase kinase-3β). Cell viability through MTT assay was also evaluated in two different brain cell lines, namely non-tumorigenic D3 human brain endothelial cells (hCMEC/D3) and NSC-34 motor neurons. Furthermore, and using GC, 21 pesticides residues were screened.

RESULTS

Regarding chemical composition, chromatographic analysis revealed the presence of several flavonoids, phenolic acids, curcuminoids, phenolic diterpenoids, one alkaloid and one naphthodianthrone in the seven decoctions. All extracts were able to scavenge free radicals and were moderate glycogen synthase kinase-3β inhibitors; however, they displayed weak to moderate acetylcholinesterase and butyrylcholinesterase inhibition. G. biloba and L. angustifolia decoctions were the less cytotoxic to hCMEC/D3 and NSC-34 cell lines. No pesticides residues were detected.

CONCLUSIONS

The results extend the knowledge on the potential use of plant extracts to combat multifactorial disorders, giving new insights into therapeutic avenues for Alzheimer's disease.

Mitochondrial and Neuronal Dysfunctions in L1 Mutant Mice

Adhesion molecules regulate cell proliferation, migration, survival, neuritogenesis, synapse formation and synaptic plasticity during the nervous system’s development and in the adult. Among such molecules, the neural cell adhesion molecule L1 contributes to these functions during development, and in synapse formation, synaptic plasticity and regeneration after trauma. Proteolytic cleavage of L1 by different proteases is essential for these functions. A proteolytic fragment of 70 kDa (abbreviated L1-70) comprising part of the extracellular domain and the transmembrane and intracellular domains was shown to interact with mitochondrial proteins and is suggested to be involved in mitochondrial functions. To further determine the role of L1-70 in mitochondria, we generated two lines of gene-edited mice expressing full-length L1, but no or only low levels of L1-70. We showed that in the absence of L1-70, mitochondria in cultured cerebellar neurons move more retrogradely and exhibit reduced mitochondrial membrane potential, impaired Complex I activity and lower ATP levels compared to wild-type littermates. Neither neuronal migration, neuronal survival nor neuritogenesis in these mutants were stimulated with a function-triggering L1 antibody or with small agonistic L1 mimetics. These results suggest that L1-70 is important for mitochondrial homeostasis and that its absence contributes to the L1 syndrome phenotypes.

Effects of transcranial magnetic stimulation on neurobiological changes in Alzheimer's disease (Review)

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive decline and brain neuronal loss. A pioneering field of research in AD is brain stimulation via electromagnetic fields (EMFs), which may produce clinical benefits. Noninvasive brain stimulation techniques, such as transcranial magnetic stimulation (TMS), have been developed to treat neurological and psychiatric disorders. The purpose of the present review is to identify neurobiological changes, including inflammatory, neurodegenerative, apoptotic, neuroprotective and genetic changes, which are associated with repetitive TMS (rTMS) treatment in patients with AD. Furthermore, it aims to evaluate the effect of TMS treatment in patients with AD and to identify the associated mechanisms. The present review highlights the changes in inflammatory and apoptotic mechanisms, mitochondrial enzymatic activities, and modulation of gene expression (microRNA expression profiles) associated with rTMS or sham procedures. At the molecular level, it has been suggested that EMFs generated by TMS may affect the cell redox status and amyloidogenic processes. TMS may also modulate gene expression by acting on both transcriptional and post‑transcriptional regulatory mechanisms. TMS may increase brain cortical excitability, induce specific potentiation phenomena, and promote synaptic plasticity and recovery of impaired functions; thus, it may re‑establish cognitive performance in patients with AD.

Improved synthesis of an ergothioneine PET radioligand for imaging oxidative stress in Alzheimer's disease

L-ergothioneine (ERGO) is a potent antioxidant with cytoprotective effects. To study ERGO biodistribution and detect oxidative stress in vivo, we report an efficient and reproducible preparation of [¹¹ C]-labeled ERGO PET radioligand based on protecting the histidine carboxylic group with a methyl ester. Overall, this new protection approach using methyl ester improved the chemical yield of a 4-step reaction from 14% to 24% compared to the previous report using t-butyl ester. The [¹¹ C]CH₃ methylation of the precursor provided the desired product with 55 ± 10% radiochemical purity and a molar activity of 450 ± 200 TBq/mmol. The [¹¹ C]ERGO radioligand was able to detect threshold levels of oxidative stress in a preclinical animal model of Alzheimer's disease.

Metabolic Features of Brain Function with Relevance to Clinical Features of Alzheimer and Parkinson Diseases

Brain metabolism is comprised in Alzheimer’s disease (AD) and Parkinson’s disease (PD). Since the brain primarily relies on metabolism of glucose, ketone bodies, and amino acids, aspects of these metabolic processes in these disorders—and particularly how these altered metabolic processes are related to oxidative and/or nitrosative stress and the resulting damaged targets—are reviewed in this paper. Greater understanding of the decreased functions in brain metabolism in AD and PD is posited to lead to potentially important therapeutic strategies to address both of these disorders, which cause relatively long-lasting decreased quality of life in patients.

Multivariate Assessment of Lipoxidative Metabolites, Trace Biometals, and Antioxidant and Detoxifying Activities in the Cerebrospinal Fluid Define a Fingerprint of Preclinical Stages of Alzheimer’s Disease

Background: There exists considerable interest in the identification of molecular traits during early stages of Alzheimer’s disease (AD). Mild cognitive impairment (MCI) is considered the closest prodromal stage of AD, and to develop gradually from earlier stages although not always progresses to AD. Classical cerebrospinal fluid (CSF) AD biomarkers, amyloid-β peptides and tau/p-tau proteins, have been measured in prodromal stages yet results are heterogeneous and far from conclusive. Therefore, there exists a pressing need to identify a neurochemical signature for prodromal stages and to predict which cases might progress to AD. Objective: Exploring potential CSF biomarkers related to brain oxidative and inorganic biochemistry during prodromal stages of the disease. Methods: We have analyzed CSF levels of lipoxidative markers (MDA and 8-isoF2α), biometals (Cu, Zn, Se, Mn, and Fe), iron-transport protein transferrin (TFER), antioxidant enzymes (SOD and GPx4), detoxifying enzymes (GST and BuChE), as well as classical amyloid-β and total and phosphorylated tau, in cognitively healthy controls, patients with MCI, and subjects exhibiting subjective memory complaints (SMC). Results: Inter-group differences for several variables exhibit differentiable trends along the HC ⟶ SMC ⟶ MCI sequence. More interestingly, the combination of Se, Cu, Zn, SOD, TFER, and GST variables allow differentiable fingerprints for control subjects and each prodromal stage. Further, multivariate scores correlate positively with neurocognitive In-Out test, hence with both episodic memory decline and prediction to dementia. Conclusion: We conclude that changes in the CSF biochemistry related to brain oxidative defense and neurometallomics might provide more powerful and accurate diagnostic tools in preclinical stages of AD.

Deregulated mitochondrial microRNAs in Alzheimer's disease: Focus on synapse and mitochondria

Alzheimer's disease (AD) is the most common cause of dementia and is currently one of the biggest public health concerns in the world. Mitochondrial dysfunction in neurons is one of the major hallmarks of AD. Emerging evidence suggests that mitochondrial miRNAs potentially play important roles in the mitochondrial dysfunctions, focusing on synapse in AD progression. In this meta-analysis paper, a comprehensive literature review was conducted to identify and discuss the (1) role of mitochondrial miRNAs that regulate mitochondrial and synaptic functions; (2) the role of various factors such as mitochondrial dynamics, biogenesis, calcium signaling, biological sex, and aging on synapse and mitochondrial function; (3) how synapse damage and mitochondrial dysfunctions contribute to AD; (4) the structure and function of synapse and mitochondria in the disease process; (5) latest research developments in synapse and mitochondria in healthy and disease states; and (6) therapeutic strategies that improve synaptic and mitochondrial functions in AD. Specifically, we discussed how differences in the expression of mitochondrial miRNAs affect ATP production, oxidative stress, mitophagy, bioenergetics, mitochondrial dynamics, synaptic activity, synaptic plasticity, neurotransmission, and synaptotoxicity in neurons observed during AD. However, more research is needed to confirm the locations and roles of individual mitochondrial miRNAs in the development of AD.

Assessment of lipophilic fluorescence products in β-amyloid-induced cognitive decline: A parallel track in hippocampus, CSF, plasma and erythrocytes

BACKGROUND

Oxidative stress implicates in Alzheimer's disease (AD) pathophysiology, and associates with the creation of end products of free radical reactions, are known as lipophilic fluorescent products (LFPs). This study aimed to evaluate the probable parallel alterations in the spectral properties of the LFPs in the hippocampus tissues, cerebrospinal fluid (CSF), plasma, and erythrocytes during AD model induction by intra-cerebroventricular (ICV) amyloid β-protein fragment 25-35 (Aβ) injection.

METHODS

Male rats received an intra-ICV injection of Aβ. Hippocampus, CSF, plasma, and erythrocytes were harvested at 5, 14, and 21 days after Aβ injection. The fluorescent intensity of LFPs was assessed by spectrofluorimetry using synchronous fluorescence spectra 25 (SYN 25) and 50 (SYN 50) in the range of 250-500 nm. Hippocampal tissue malondialdehyde (MDA) and superoxide dismutase (SOD) were also measured. Cognitive alterations were evaluated using Morris water maze (MWM) test.

RESULTS

The parallel significant rise in the fluorescence intensity of LFPs was detected in the hippocampus, CSF, plasma, and erythrocytes, 14, and 21 days after ICV-Aβ injection. These alterations were found in both types of synchronous spectra 25, and 50, and were coincided with hippocampal cognitive decline, the MDA rise, and decrease of SOD activity. There was a positive correlation between hippocampus homogenate, and plasma or CSF rise in fluorescence intensity.

CONCLUSION

Data showed that the Aβ increased hippocampal MDA, and decreased SOD activity, led to a higher rate of oxidative products and subsequently resulted in an increase in LFPs fluorescence intensity during the development of cognitive decline. LFPs' alterations reflect a comprehensive view of tissue redox status. The fluorescence properties of LFPs indicate their composition, which may pave the way to trace the different pathological states.

Epigallocatechin-3-gallate improves chronic alcohol-induced cognitive dysfunction in rats by interfering with neuro-inflammatory, cell death and oxido-nitrosative cascade

Alcohol consumption for a longer period of time is linked with neuronal damage and an increase in inflammatory signaling resulting in cell death and dementia. Natural compounds are the focus of research due to their high efficacy and good safety profile. Here we have investigated the effect of chronic epigallocatechin-3-gallate (EGCG) administration against the alcohol-induced cognitive deficit rats. Male Wistar rats were exposed to the 12% ethanol (10 g/kg; oral gavage) for ten weeks and treated with EGCG (25, 50, and 100 mg/kg) for the same duration. Ethanol exposure led to the impaired spatial memory and learning in rats assessed using the Morris water maze and elevated plus-maze test. Further, we assessed the role of EGCG in mitigating the oxidative stress, neuroinflammatory and cell death signaling associated markers. Co-administration with EGCG significantly prevented all the behavioral, biochemical and molecular alterations in the different brain regions of ethanol-treated rats in a dose-dependent manner. EGCG suppressed the acetylcholinesterase activity, increased oxidative-nitrosative stress, cytokines (TNF-alpha and IL-1beta), NF-kappa β and caspase-3 levels in both the cortex and hippocampus of ethanol-treated rats. Our preliminary study demonstrated that EGCG improves the oxido-nitrosative stress, inflammation, and cell death signaling associated with ethanol-induced cognitive dysfunction. This suggests the potential role of EGCG in mitigating the cognitive deficits associated with chronic alcohol consumption.

DCE-MRI of Brain Fluid Barriers: In Vivo Water Cycling at the Human Choroid Plexus

Metabolic deficits at brain-fluid barriers are an increasingly recognized feature of cognitive decline in older adults. At the blood-cerebrospinal fluid barrier, water is transported across the choroid plexus (CP) epithelium against large osmotic gradients via processes tightly coupled to activity of the sodium/potassium pump. Here, we quantify CP homeostatic water exchange using dynamic contrast-enhanced MRI and investigate the association of the water efflux rate constant (k_co) with cognitive dysfunction in older individuals. Temporal changes in the longitudinal relaxation rate constant (R₁) after contrast agent bolus injection were measured in a CP region of interest in 11 participants with mild cognitive dysfunction [CI; 73 ± 6 years] and 28 healthy controls [CN; 72 ± 7 years]. k_co was determined from a modified two-site pharmacokinetic exchange analysis of the R₁ time-course. K^trans, a measure of contrast agent extravasation to the interstitial space was also determined. Cognitive function was assessed by neuropsychological test performance. k_co averages 5.8 ± 2.7 s^-1 in CN individuals and is reduced by 2.4 s^-1 [ca. 40%] in CI subjects. Significant associations of k_co with global cognition and multiple cognitive domains are observed. K^trans averages 0.13 ± 0.07 min^-1 and declines with age [-0.006 ± 0.002 min^-1 yr^-1], but shows no difference between CI and CN individuals or association with cognitive performance. Our findings suggest that the CP water efflux rate constant is associated with cognitive dysfunction and shows an age-related decline in later life, consistent with the metabolic disturbances that characterize brain aging.

Extracellular Vesicles under Oxidative Stress Conditions: Biological Properties and Physiological Roles

Under physio-pathological conditions, cells release membrane-surrounded structures named Extracellular Vesicles (EVs), which convey their molecular cargo to neighboring or distant cells influencing their metabolism. Besides their involvement in the intercellular communication, EVs might represent a tool used by cells to eliminate unnecessary/toxic material. Here, we revised the literature exploring the link between EVs and redox biology. The first proof of this link derives from evidence demonstrating that EVs from healthy cells protect target cells from oxidative insults through the transfer of antioxidants. Oxidative stress conditions influence the release and the molecular cargo of EVs that, in turn, modulate the redox status of target cells. Oxidative stress-related EVs exert both beneficial or harmful effects, as they can carry antioxidants or ROS-generating enzymes and oxidized molecules. As mediators of cell-to-cell communication, EVs are also implicated in the pathophysiology of oxidative stress-related diseases. The review found evidence that numerous studies speculated on the role of EVs in redox signaling and oxidative stress-related pathologies, but few of them unraveled molecular mechanisms behind this complex link. Thus, the purpose of this review is to report and discuss this evidence, highlighting that the analysis of the molecular content of oxidative stress-released EVs (reminiscent of the redox status of originating cells), is a starting point for the use of EVs as diagnostic and therapeutic tools in oxidative stress-related diseases.

Mitochondrial dysfunction: A potential target for Alzheimer's disease intervention and treatment

Alzheimer's disease (AD) is an irreversible neurodegenerative brain disorder which manifests as a progressive decline in cognitive function. Mitochondrial dysfunction plays a critical role in the early stages of AD, and advances the progression of this age-related neurodegenerative disorder. Therefore, it can be a potential target for interventions to treat AD. Several therapeutic strategies to target mitochondrial dysfunction have gained significant attention in the preclinical stage, but the clinical trials performed to date have shown little progress. Thus, we discuss the mechanisms and strategies of different therapeutic agents for targeting mitochondrial dysfunction in AD. We hope that this review will inspire and guide the development of efficient AD drugs in the future.

The Causal Role of Lipoxidative Damage in Mitochondrial Bioenergetic Dysfunction Linked to Alzheimer's Disease Pathology

Current shreds of evidence point to the entorhinal cortex (EC) as the origin of the Alzheimer’s disease (AD) pathology in the cerebrum. Compared with other cortical areas, the neurons from this brain region possess an inherent selective vulnerability derived from particular oxidative stress conditions that favor increased mitochondrial molecular damage with early bioenergetic involvement. This alteration of energy metabolism is the starting point for subsequent changes in a multitude of cell mechanisms, leading to neuronal dysfunction and, ultimately, cell death. These events are induced by changes that come with age, creating the substrate for the alteration of several neuronal pathways that will evolve toward neurodegeneration and, consequently, the development of AD pathology. In this context, the present review will focus on description of the biological mechanisms that confer vulnerability specifically to neurons of the entorhinal cortex, the changes induced by the aging process in this brain region, and the alterations at the mitochondrial level as the earliest mechanism for the development of AD pathology. Current findings allow us to propose the existence of an altered allostatic mechanism at the entorhinal cortex whose core is made up of mitochondrial oxidative stress, lipid metabolism, and energy production, and which, in a positive loop, evolves to neurodegeneration, laying the basis for the onset and progression of AD pathology.

Dynamic Interplay between Copper Toxicity and Mitochondrial Dysfunction in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder, affecting millions of people worldwide, a number expected to exponentially increase in the future since no effective treatments are available so far. AD is characterized by severe cognitive dysfunctions associated with neuronal loss and connection disruption, mainly occurring in specific brain areas such as the hippocampus, cerebral cortex, and amygdala, compromising memory, language, reasoning, and social behavior. Proteomics and redox proteomics are powerful techniques used to identify altered proteins and pathways in AD, providing relevant insights on cellular pathways altered in the disease and defining novel targets exploitable for drug development. Here, we review the main results achieved by both -omics techniques, focusing on the changes occurring in AD mitochondria under oxidative stress and upon copper exposure. Relevant information arises by the comparative analysis of these results, evidencing alterations of common mitochondrial proteins, metabolic cycles, and cascades. Our analysis leads to three shared mitochondrial proteins, playing key roles in metabolism, ATP generation, oxidative stress, and apoptosis. Their potential as targets for development of innovative AD treatments is thus suggested. Despite the relevant efforts, no effective drugs against AD have been reported so far; nonetheless, various compounds targeting mitochondria have been proposed and investigated, reporting promising results.

Neuroprotective Roles of the Reverse Transsulfuration Pathway in Alzheimer's Disease

The reverse transsulfuration pathway has emerged as a central hub that integrates the metabolism of sulfur-containing amino acids and redox homeostasis. Transsulfuration involves the transfer of sulfur from homocysteine to cysteine. Cysteine serves as the precursor for several sulfur-containing molecules, which play diverse roles in cellular processes. Recent evidence shows that disruption of the flux through the pathway has deleterious consequences. In this review article, I will discuss the actions and regulation of the reverse transsulfuration pathway and its links to other metabolic pathways, which are disrupted in Alzheimer’s disease (AD). The potential nodes of therapeutic intervention are also discussed, which may pave the way for the development of novel treatments.

Insulin resistance, oxidative stress and mitochondrial defects in Ts65dn mice brain: A harmful synergistic path in down syndrome

Dysregulation of brain insulin signaling with reduced downstream neuronal survival and plasticity mechanisms are fundamental abnormalities observed in Alzheimer disease (AD). This phenomenon, known as brain insulin resistance, is associated with poor cognitive performance and is driven by the inhibition of IRS1. Since Down syndrome (DS) and AD neuropathology share many common features, we investigated metabolic aspects of neurodegeneration in DS and whether they contribute to early onset AD in DS. We evaluated levels and activation of proteins belonging to the insulin signaling pathway (IR, IRS1, BVR-A, MAPK, PTEN, Akt, GSK3β, PKCζ, AS160, GLUT4) in the frontal cortex of Ts65dn (DS model) (n = 5-6/group) and euploid mice (n = 6/group) at different ages (1, 3, 9 and 18 months). Furthermore, we analyzed whether changes of brain insulin signaling were associated with alterations of: (i) proteins regulating brain energy metabolism (mitochondrial complexes, hexokinase-II, Sirt1); (ii) oxidative stress (OS) markers (iii) APP cleavage; and (iv) proteins mediating synaptic plasticity mechanisms (PSD95, syntaxin-1 and BDNF). Ts65dn mice showed an overall impairment of the above-mentioned pathways, mainly characterized by defects of proteins activation state. Such alterations start early in life (at 1 month, during brain maturation). In particular, accumulation of inhibited IRS1, together with the uncoupling among the proteins downstream from IRS1 (brain insulin resistance), characterize Ts65dn mice. Furthermore, reduced levels of mitochondrial complexes and Sirt1, as well as increased indices of OS also were observed. These alterations precede the accumulation of APP-C99 in Ts65dn mice. Tellingly, oxidative stress levels were negatively associated with IR, IRS1 and AS160 activation as well as mitochondrial complexes levels in Ts65dn mice, suggesting a role for oxidative stress in the observed alterations. We propose that a close link exists among brain insulin resistance, mitochondrial defects and OS that contributes to brain dysfunctions observed in DS, likely favoring the development of AD in DS.

Beneficial effects of combined administration of fluoxetine and mitochondria-targeted antioxidant at in behavioural and molecular studies in mice model of depression

Chronic or recurrent stress is associated with reactive oxygen species (ROS) overproduction and can lead to oxidative damage, which plays important roles in neurodegenerative diseases. Mito - TEMPO is an antioxidant targeted at mitochondria. The aim of the presented study was to assess antidepressant and antioxidant efficacy of Mito - TEMPO administered alone or with fluoxetine in mice exposed to chronic stress. The evaluation of the antidepressant-like activity was based on forced swimming test (FST) and tail suspension test (TST). In order to evaluate the antioxidant potential, the level of mRNA expression of Adora1, Ogg1, Msra, Nrf2 and Tfam in the hippocampus of mice was determined. Behavioural research data showed the antidepressant effect of fluoxetine and Mito - TEMPO administered to mice alone and in combination. The molecular research results indicate a significant impact of chronic stress on the oxidation-reduction balance and an antioxidant effect of Mito - TEMPO. The results obtained in the study suggest that Mito - TEMPO protects DNA against oxidative damage and may be beneficial in the way of cellular function improvement under the conditions of chronic stress. Adora1, Msra, Nrf2 and Tfam genes may be involved in mediating the antioxidant effect of the combined treatment with fluoxetine and Mito - TEMPO.

Isoliquiritigenin Confers Neuroprotection and Alleviates Amyloid-β42-Induced Neuroinflammation in Microglia by Regulating the Nrf2/NF-κB Signaling

Background

Neuroinflammation and oxidative stress are two major pathological characteristics of Alzheimer's disease (AD). Amyloid-β oligomers (AβO), a toxic form of Aβ, promote the neuroinflammation and oxidative stress in the development of AD. Isoliquiritigenin (ISL), a natural flavonoid isolated from the root of liquorice, has been shown to exert inhibitory effects on inflammatory response and oxidative stress.

Objectives

The main purpose of this study is to assess the influence of ISL on inflammatory response and oxidative stress in BV2 cells stimulated with AβO, and to explore the underlying molecular mechanisms.

Methods

3-(4,5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H- tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) cytotoxicity assays were used to assess the toxic or protective effects of ISL. The expression levels of interleukin-1β, interleukin-6, and tumor necrosis factor-α were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assays. Morphological changes in BV2 cells were assessed by immunofluorescence method. Nitric oxide (NO) assay kit was used to determinate the NO production. Western blot, qRT-PCR and immunofluorescence were used to explore the underlying molecular mechanisms.

Results

ISL treatment reduced the production of inflammatory cytokines and NO, and alleviated the morphological changes in BV2 cells induced by AβO. ISL treatment further protected N2a cells from the toxic medium of AβO-stimulated BV2 cells. ISL activated nuclear factor erythroid-2 related factor 2 (Nrf2) signaling and suppressed nuclear factor-κB (NF-κB) signaling in BV2 cells.

Conclusion

ISL suppresses AβO-induced inflammation and oxidative stress in BV2 cells via the regulation of Nrf2/NF-κB signaling. Therefore, ISL indirectly protects neurons from the damage of toxic conditioned media.

Microstructural and Cerebral Blood Flow Abnormalities in Subjective Cognitive Decline Plus: Diffusional Kurtosis Imaging and Three-Dimensional Arterial Spin Labeling Study

Objective: To explore microstructural and cerebral blood flow (CBF) abnormalities in individuals with subjective cognitive decline plus (SCD plus) using diffusional kurtosis imaging (DKI) and three-dimensional (3D) arterial spin labeling (ASL). Methods: Twenty-seven patients with SCD plus, 31 patients with amnestic mild cognitive impairment (aMCI), and 33 elderly controls (ECs) were recruited and underwent DKI and 3D ASL using a GE 3.0-T MRI. Mean kurtosis (MK), fractional anisotropy (FA), mean diffusivity (MD), and CBF values were acquired from 24 regions of interest (ROIs) in the brain, including the bilateral hippocampal (Hip) subregions (head, body, and tail), posterior cingulate cortex (PCC), precuneus, dorsal thalamus subregions (anterior nucleus, ventrolateral nucleus, and medial nucleus), lenticular nucleus, caput nuclei caudati, white matter (WM) of the frontal lobe, and WM of the occipital lobe. Pearson's correlation analysis was performed to assess the relationships among the DKI-derived parameters, CBF values, and key neuropsychological tests for SCD plus. Results: Compared with ECs, participants with SCD plus showed a significant decline in MK and CBF values, mainly in the Hip head and PCC, and participants with aMCI exhibited more significant abnormalities in the MK and CBF values than individuals with ECs and SCD plus in multiple regions. Combined MK values showed better discrimination between patients with SCD plus and ECs than that obtained using CBF levels, with areas under the receiver operating characteristic (ROC) curve (AUC) of 0.874 and 0.837, respectively. Similarly, the AUC in discriminating SCD plus from aMCI patients obtained using combined MK values was 0.823, which was also higher than the combined AUC of 0.779 obtained using CBF values. Moreover, MK levels in the left Hip (h) and left PCC positively correlated with the auditory verbal learning test-delayed recall (AVLT-DR) score in participants with SCD plus. By contrast, only the CBF value in the left Hip head positively correlated with the AVLT-DR score. Conclusions: Our results provide new evidence of microstructural and CBF changes in patients with SCD plus. MK may be used as an early potential neuroimaging biomarker and may be a more sensitive DKI parameter than CBF at the very early stage of Alzheimer's disease (AD).

The Potential Roles of Redox Enzymes in Alzheimer's Disease: Focus on Thioredoxin

Alzheimer's disease (AD) is the most common neurodegenerative diseases. Increasing studies have demonstrated the critical importance for redox proteins mediating neuronal protection in models of AD. This review briefly describes some of the risk factors contributing to AD, specifically highlighting the important roles of oxidative stress in the pathology of AD. Then this article concisely introduces the dysregulation and functions of two main redox enzymes, peroxiredoxins and glutaredoxins, in AD models. This review emphasizes the neuroprotective role of the third redox enzyme thioredoxin (Trx), an important multifunctional protein regulating cellular redox status. This commentary not only summarizes the alterations of Trx expression in AD patients and models, but also reviews the potential effects and mechanisms of Trx, Trx-related molecules and Trx-inducing compounds against AD. In conclusion, Trx has a potential neuroprotection in AD and may be very promising for clinical therapy of AD in the future.

The Potential Roles of Redox Enzymes in Alzheimer's Disease: Focus on Thioredoxin

Alzheimer's disease (AD) is the most common neurodegenerative diseases. Increasing studies have demonstrated the critical importance for redox proteins mediating neuronal protection in models of AD. This review briefly describes some of the risk factors contributing to AD, specifically highlighting the important roles of oxidative stress in the pathology of AD. Then this article concisely introduces the dysregulation and functions of two main redox enzymes, peroxiredoxins and glutaredoxins, in AD models. This review emphasizes the neuroprotective role of the third redox enzyme thioredoxin (Trx), an important multifunctional protein regulating cellular redox status. This commentary not only summarizes the alterations of Trx expression in AD patients and models, but also reviews the potential effects and mechanisms of Trx, Trx-related molecules and Trx-inducing compounds against AD. In conclusion, Trx has a potential neuroprotection in AD and may be very promising for clinical therapy of AD in the future.