Mitochondrial dysfunctions, oxidative stress and neuroinflammation as therapeutic targets for neurodegenerative diseases: An update on current advances and impediments

Sleep restriction promotes brain oxidative stress and inflammation, and aggravates cognitive impairment in insulin-resistant mice

Sleep deprivation and insulin resistance (IR) are two risk factors for Alzheimer's disease. As the population of people with IR increases and sleep restriction (SR) due to staying up late becomes the "new normal", it is necessary to investigate the effects and molecular pathogenesis of chronic SR on cognitive function in insulin resistance. In this study, 4-week-old mice were fed a high-fat diet (HFD) for 8 weeks to establish IR model, and then the mice were subjected to SR for 21 days, and related indicators were assessed, including cognitive capacity, apoptosis, oxidative stress, glial cell activation, inflammation, blood-brain barrier (BBB) permeability and adiponectin levels, for exploring the potential regulatory mechanisms. Compared with control group, IR mice showed impaired cognitive capacity, meanwhile, SR not only promoted Bax/Bcl2-induced hippocampal neuronal cell apoptosis and Nrf2/HO1- induced oxidative stress, but also increased microglia activation and inflammatory factor levels and BBB permeability, thus aggravating the cognitive impairment in IR mice. Consequently, changing bad living habits and ensuring sufficient sleep are important intervention strategies to moderate the aggravation of IR-induced cognitive impairment.

The anti-inflammatory effects of itaconate and its derivatives in neurological disorders

Almost 16 % of the global population is affected by neurological disorders, including neurodegenerative and cerebral neuroimmune diseases, triggered by acute or chronic inflammation. Neuroinflammation is recognized as a common pathogenic mechanism in a wide array of neurological conditions including Alzheimer's disease, Parkinson's disease, postoperative cognitive dysfunction, stroke, traumatic brain injury, and multiple sclerosis. Inflammatory process in the central nervous system (CNS) can lead to neuronal damage and neuronal apoptosis, consequently exacerbating these diseases. Itaconate, an immunomodulatory metabolite from the tricarboxylic acid cycle, suppresses neuroinflammation and modulates the CNS immune response. Emerging human studies suggest that itaconate levels in plasma and cerebrospinal fluid may serve as biomarkers associated with inflammatory responses in neurological disorders. Preclinical studies have shown that itaconate and its highly cell-permeable derivatives are promising candidates for preventing and treating neuroinflammation-related neurological disorders. The underlying mechanism may involve the regulation of immune cells in the CNS and neuroinflammation-related signaling pathways and molecules including Nrf2/KEAP1 signaling pathway, reactive oxygen species, and NLRP3 inflammasome. Here, we introduce the metabolism and function of itaconate and the synthesis and development of its derivatives. We summarize the potential impact and therapeutic potential of itaconate and its derivatives on brain immune cells and the associated signaling pathways and molecules, based on preclinical evidence via various neurological disorder models. We also discuss the challenges and potential solutions for clinical translation to promote further research on itaconate and its derivatives for neuroinflammation-related neurological disorders.

Association between glioma and neurodegenerative diseases risk: a two-sample bi-directional Mendelian randomization analysis

Background

Earlier observational studies have demonstrated a correlation between glioma and the risk of neurodegenerative diseases (NDs), but the causality and direction of their associations remain unclear. The objective of this study was to ascertain the causal link between glioma and NDs using Mendelian randomization (MR) methodology.

Methods

Genome-wide association study (GWAS) data were used in a two-sample bi-directional MR analysis. From the largest meta-analysis GWAS, encompassing 18,169 controls and 12,488 cases, summary statistics data on gliomas was extracted. Summarized statistics for NDs, including Alzheimer's disease (AD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD) were obtained from the GWAS of European ancestry. Inverse variance weighted (IVW) method was elected as the core MR approach with weighted median (WM) method and MR-Egger method as complementary methods. In addition, sensitivity analyses were performed. A Bonferroni correction was used to correct the results.

Results

Genetically predicted glioma had been related to decreased risk of AD. Specifically, for all glioma (IVW: OR = 0.93, 95% CI = 0.90-0.96, p = 4.88 × 10-6) and glioblastoma (GBM) (IVW: OR = 0.93, 95% CI = 0.91-0.95, p = 5.11 × 10-9). We also found that genetically predicted all glioma has a suggestive causative association with MS (IVW: OR = 0.90, 95% CI = 0.81-1.00, p = 0.045). There was no evidence of causal association between glioma and ALS or PD. According to the results of reverse MR analysis, no discernible causal connection of NDs was found on glioma. Sensitivity analyses validated the robustness of the above associations.

Conclusion

We report evidence in support of potential causal associations of different glioma subtypes with AD and MS. More studies are required to uncover the underlying mechanisms of these findings.

Cornus officinalis Sieb. Et Zucc. attenuates Aβ25-35-induced mitochondrial damage and neuroinflammation in mice by modulating the ERK pathway

BACKGROUND

Cornus officinalis Sieb. Et Zucc. has the efficacy of tonifying the marrow and filling up the essence, breaking up the accumulation and opening up the orifices. Our research team found that CoS extracts were protective against Aβ25-35-induced memory impairment in mice. However, the pharmacodynamic components and mechanisms by which CoS improves AD have yet to be thoroughly explored and investigated.

PURPOSE

This study focused on exploring the bioactive components and pharmacodynamic mechanisms of CoS aqueous extract underlying mitochondrial damage and neuroinflammation to improve Aβ25-35-induced AD.

METHODS

AD mouse models were generated using Aβ25-35 brain injections. Different doses of CoS aqueous extract were orally administered to mice for 28 days. The cognitive function, neuronal and synaptic damage, mitochondrial damage (mitochondrial length, mitochondrial fusion fission-related protein expression), neuroglial activation, and immune inflammatory factor and ERK pathway-related protein levels of mice were assessed. The CoS aqueous extracts components were identified using UPLC-TQ/MS and screened for cellular activity. Midivi-1 (Drp1 inhibitor) or PD98059 (ERK inhibitor) was added to Aβ25-35-exposed PC12 cells to assess whether CoS and its active compounds mMorB and CorE regulate mitochondrial fission through ERK/Drp1. PC12-N9 cells were cocultured to investigate whether mMorB and CorE could regulate mitochondrial division through the ERK pathway to modulate neuroinflammation.

RESULTS

CoS improved exploration and memory in AD mice, reduced synaptic and mitochondrial damage in their hippocampus, and modulated disturbed mitochondrial dynamics. Moreover, CoS inhibited ERK pathway signaling and attenuated abnormal activation of glial cells and secondary immune inflammatory responses. Additionally, in vitro experiments revealed that CoS and its compounds 7β-O-methylmorroniside (mMorB) and Cornusdiridoid E (CorE) ameliorated mitochondrial injury caused by Aβ25-35 in PC12 cells through inhibition of the ERK/Drp1 pathway. Meanwhile, mMorB and CorE ameliorated cellular inflammation by inhibiting the Ras/ERK/CREB signaling pathway.

CONCLUSION

CoS aqueous extract ameliorates behavioral deficits and brain damage in Aβ25-35-induced AD mice by modulating the ERK pathway to attenuate mitochondrial damage and neuroinflammation, and the compounds mMorB and CorE are the therapeutically active ingredients.

Exploring the therapeutic potential of Nelumbo nucifera leaf extract against amyloid-beta-induced toxicity in the Caenorhabditis elegans model of Alzheimer's disease

Introduction: Alzheimer's disease (AD) represents a critical global health challenge with limited therapeutic options, prompting the exploration of alternative strategies. A key pathology in AD involves amyloid beta (Aβ) aggregation, and targeting both Aβ aggregation and oxidative stress is crucial for effective intervention. Natural compounds from medicinal and food sources have emerged as potential preventive and therapeutic agents, with Nelumbo nucifera leaf extract (NLE) showing promising properties. Methods: In this study, we utilized transgenic Caenorhabditis elegans (C. elegans) models to investigate the potential of NLE in countering AD and to elucidate the underlying mechanisms. Various assays were employed to assess paralysis rates, food-searching capabilities, Aβ aggregate accumulation, oxidative stress, lifespan under stress conditions, and the expression of stress-resistance-related proteins. Additionally, autophagy induction was evaluated by measuring P62 levels and the formation of LGG-1+ structures, with RNAi-mediated inhibition of autophagy-related genes to confirm the mechanisms involved. Results: The results demonstrated that NLE significantly reduced paralysis rates in CL4176 and CL2006 worms while enhancing food-searching capabilities in CL2355 worms. NLE also attenuated Aβ aggregate accumulation and mitigated Aβ-induced oxidative stress in C. elegans. Furthermore, NLE extended the lifespan of worms under oxidative and thermal stress conditions, while concurrently increasing the expression of stress-resistance-related proteins, including SOD-3, GST-4, HSP-4, and HSP-6. Moreover, NLE induced autophagy in C. elegans, as evidenced by reduced P62 levels in BC12921 worms and the formation of LGG-1+ structures in DA2123 worms. The RNAi-mediated inhibition of autophagy-related genes, such as bec-1 and vps-34, negated the protective effects of NLE against Aβ-induced paralysis and aggregate accumulation. Discussion: These findings suggest that NLE ameliorates Aβ-induced toxicity by activating autophagy in C. elegans. The study underscores the potential of NLE as a promising candidate for further investigation in AD management, offering multifaceted approaches to mitigate AD-related pathology and stress-related challenges.

Modulatory Effects of Phytochemicals on Gut-Brain Axis: Therapeutic Implication

This article explores the potential therapeutic implications of phytochemicals on the gut-brain axis (GBA), which serves as a communication network between the central nervous system and the enteric nervous system. Phytochemicals, which are compounds derived from plants, have been shown to interact with the gut microbiota, immune system, and neurotransmitter systems, thereby influencing brain function. Phytochemicals such as polyphenols, carotenoids, flavonoids, and terpenoids have been identified as having potential therapeutic implications for various neurological disorders. The GBA plays a critical role in the development and progression of various neurological disorders, including Parkinson's disease, multiple sclerosis, depression, anxiety, and autism spectrum disorders. Dysbiosis, or an imbalance in gut microbiota composition, has been associated with a range of neurological disorders, suggesting that modulating the gut microbiota may have potential therapeutic implications for these conditions. Although these findings are promising, further research is needed to elucidate the optimal use of phytochemicals in neurological disorder treatment, as well as their potential interactions with other medications. The literature review search was conducted using predefined search terms such as phytochemicals, gut-brain axis, neurodegenerative, and Parkinson in PubMed, Embase, and the Cochrane library.

Glymphatic pathway: An emerging perspective in the pathophysiology of neurodegenerative diseases

The central nervous system (CNS) is widely recognized as the only organ system without lymphatic capillaries to promote the removal of interstitial metabolic by-products. Thus, the newly identified glymphatic system which provides a pseudolymphatic activity in the nervous system has been focus of latest research in neurosciences. Also, findings reported that, sleep stimulates the elimination actions of glymphatic system and is linked to normal brain homeostatis. The CNS is cleared of potentially hazardous compounds via the glymphatic system, particularly during sleep. Any age-related alterations in brain functioning and pathophysiology of various neurodegenerative illnesses indicates the disturbance of the brain's glymphatic system. In this context, β-amyloid as well as tau leaves the CNS through the glymphatic system, it's functioning and CSF discharge markedly altered in elderly brains as per many findings. Thus, glymphatic failure may have a potential mechanism which may be therapeutically targetable in several neurodegenerative and age-associated cognitive diseases. Therefore, there is an urge to focus for more research into the connection among glymphatic system and several potential brain related diseases. Here, in our current review paper, we reviewed current research on the glymphatic system's involvement in a number of prevalent neurodegenerative and neuropsychiatric diseases and, we also discussed several therapeutic approaches, diet and life style modifications which might be used to acquire a more thorough performance and purpose of the glymphatic system to decipher novel prospects for clinical applicability for the management of these diseases.

Geniposide effectively safeguards HT22 cells against Aβ-induced damage by activating mitophagy via the PINK1/Parkin signaling pathway

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the significant involvement of amyloid-beta (Aβ) peptide in its pathogenesis. Geniposide, derived from the versatile medicinal of Gardenia jasminoides, is one of the active compounds studied extensively. The objective was to explore the impact of geniposide on Aβ25-35-induced damage in HT22 cells, specifically focusing on its modulation of PINK1/Parkin-mediated mitophagy. In our investigation, geniposide exhibited remarkable restorative effects by enhancing cell viability and preserving the mitochondrial membrane potential. Moreover, it effectively reduced and mitigated the oxidative stress and apoptosis rates induced by Aβ25-35. Notably, geniposide exhibited the capacity to enhance autophagic flux, upregulate LC3II and Beclin-1 expression, and downregulate the expression of p62. Furthermore, geniposide positively influenced the expression of PINK1 and Parkin proteins, with molecular docking substantiating a strong interaction between geniposide and PINK1/Parkin proteins. Intriguingly, the beneficial outcomes of geniposide on alleviating the pronounced apoptosis rates, the overproduction of reactive oxygen species, and diminished the PINK1 and Parkin expression induced by Aβ25-35 were compromised by the mitophagy inhibitor cyclosporine A (CsA). Collectively, these findings suggested that geniposide potentially shields HT22 cells against neurodegenerative damage triggered by Aβ25-35 through the activation of mitophagy. The insights contribute valuable references to the defensive consequences against neurological damage of geniposide, thereby highlighting its potential as a therapeutic intervention in AD.

Psammaplin A and Its Analogs Attenuate Oxidative Stress in Neuronal Cells through Peroxisome Proliferator-Activated Receptor γ Activation

Psammaplins are sulfur containing bromotyrosine alkaloids that have shown antitumor activity through the inhibition of class I histone deacetylases (HDACs). The cytotoxic properties of psammaplin A (1), the parent compound, are related to peroxisome proliferator-activated receptor γ (PPARγ) activation, but the mechanism of action of its analogs psammaplin K (2) and bisaprasin (3) has not been elucidated. In this study, the protective effects against oxidative stress of compounds 1-3, isolated from the sponge Aplysinella rhax, were evaluated in SH-SY5Y cells. The compounds improved cell survival, recovered glutathione (GSH) content, and reduced reactive oxygen species (ROS) release at nanomolar concentrations. Psammaplins restored mitochondrial membrane potential by blocking mitochondrial permeability transition pore opening and reducing cyclophilin D expression. This effect was mediated by the capacity of 1-3 to activate PPARγ, enhancing gene expression of the antioxidant enzymes catalase, nuclear factor E2-related factor 2 (Nrf2), and glutathione peroxidase. Finally, HDAC3 activity was reduced by 1-3 under oxidative stress conditions. This work is the first description of the neuroprotective activity of 1 at low concentrations and the mechanism of action of 2 and 3. Moreover, it links for the first time the previously described effects of 1 in HDAC3 and PPARγ signaling, opening a new research field for the therapeutic potential of this compound family.

GSDMD/Drp1 signaling pathway mediates hippocampal synaptic damage and neural oscillation abnormalities in a mouse model of sepsis-associated encephalopathy

BACKGROUND

Gasdermin D (GSDMD)-mediated pyroptotic cell death is implicated in the pathogenesis of cognitive deficits in sepsis-associated encephalopathy (SAE), yet the underlying mechanisms remain largely unclear. Dynamin-related protein 1 (Drp1) facilitates mitochondrial fission and ensures quality control to maintain cellular homeostasis during infection. This study aimed to investigate the potential role of the GSDMD/Drp1 signaling pathway in cognitive impairments in a mouse model of SAE.

METHODS

C57BL/6 male mice were subjected to cecal ligation and puncture (CLP) to establish an animal model of SAE. In the interventional study, mice were treated with the GSDMD inhibitor necrosulfonamide (NSA) or the Drp1 inhibitor mitochondrial division inhibitor-1 (Mdivi-1). Surviving mice underwent behavioral tests, and hippocampal tissues were harvested for histological analysis and biochemical assays at corresponding time points. Haematoxylin-eosin staining and TUNEL assays were used to evaluate neuronal damage. Golgi staining was used to detect synaptic dendritic spine density. Additionally, transmission electron microscopy was performed to assess mitochondrial and synaptic morphology in the hippocampus. Local field potential recordings were conducted to detect network oscillations in the hippocampus.

RESULTS

CLP induced the activation of GSDMD, an upregulation of Drp1, leading to associated mitochondrial impairment, neuroinflammation, as well as neuronal and synaptic damage. Consequently, these effects resulted in a reduction in neural oscillations in the hippocampus and significant learning and memory deficits in the mice. Notably, treatment with NSA or Mdivi-1 effectively prevented these GSDMD-mediated abnormalities.

CONCLUSIONS

Our data indicate that the GSDMD/Drp1 signaling pathway is involved in cognitive deficits in a mouse model of SAE. Inhibiting GSDMD or Drp1 emerges as a potential therapeutic strategy to alleviate the observed synaptic damages and network oscillations abnormalities in the hippocampus of SAE mice.

Could protein phosphatase 2A and glycogen synthase kinase-3 beta be targeted by natural compounds to ameliorate Alzheimer's pathologies?

Alzheimer's disease (AD) is a progressive neurological disorder that impairs memory and cognitive abilities, primarily in the elderly. The burden of AD extends beyond patients, impacting families and caregivers due to the patients' reliance on assistance for daily tasks. The main features of the pathogenesis of AD are beta-amyloid plaques and neurofibrillary tangles (NFTs), that strongly correlate with oxidative stress and inflammation. NFTs result from misfolded and hyperphosphorylated tau proteins. Various studies have focused on tau phosphorylation, indicating protein phosphatase 2A (PP2A) as the primary tau phosphatase and glycogen synthase kinase-3 beta (GSK-3β) as the leading tau kinase. Experimental evidence suggests that inhibition of PP2A and increased GSK-3β activity contribute to neuroinflammation, oxidative stress, and cognitive impairment. Hence, targeting PP2A and GSK-3β with pharmacological approaches shows promise in treating AD. The use of natural compounds in the drug development for AD have been extensively studied for their antioxidant, anti-inflammatory, anti-cholinesterase, and neuroprotective properties, demonstrating therapeutic advantages in neurological diseases. Alongside the development of PP2A activator and GSK-3β inhibitor drugs, natural compounds are likely to have neuroprotective effects by increasing PP2A activity and decreasing GSK-3β levels. Therefore, based on the preclinical and clinical studies, the potential of PP2A and GSK-3β as therapeutic targets of natural compounds are highlighted in this review.

Role of the Exposome in Neurodegenerative Disease: Recent Insights and Future Directions

Neurodegenerative diseases are increasing in prevalence and place a significant burden on society. The causes are multifactorial and complex, and increasing evidence suggests a dynamic interplay between genes and the environment, emphasizing the importance of identifying and understanding the role of lifelong exposures, known as the exposome, on the nervous system. This review provides an overview of recent advances toward defining neurodegenerative disease exposomes, focusing on Parkinson's disease, amyotrophic lateral sclerosis, and Alzheimer's disease. We present the current state of the field based on emerging data, elaborate on key themes and potential mechanisms, and conclude with limitations and future directions. ANN NEUROL 2024;95:635-652.

The Role of Reactive Oxygen Species in Alzheimer's Disease: From Mechanism to Biomaterials Therapy

Alzheimer's disease (AD) is a chronic, insidious, and progressive neurodegenerative disease that remains a clinical challenge for society. The fully approved drug lecanemab exhibits the prospect of therapy against the pathological processes, while debatable adverse events conflict with the drug concentration required for the anticipated therapeutic effects. Reactive oxygen species (ROS) are involved in the pathological progression of AD, as has been demonstrated in much research regarding oxidative stress (OS). The contradiction between anticipated dosage and adverse event may be resolved through targeted transport by biomaterials and get therapeutic effects through pathological progression via regulation of ROS. Besides, biomaterials fix delivery issues by promoting the penetration of drugs across the blood-brain barrier (BBB), protecting the drug from peripheral degradation, and elevating bioavailability. The goal is to comprehensively understand the mechanisms of ROS in the progression of AD disease and the potential of ROS-related biomaterials in the treatment of AD. This review focuses on OS and its connection with AD and novel biomaterials in recent years against AD via OS to inspire novel biomaterial development. Revisiting these biomaterials and mechanisms associated with OS in AD via thorough investigations presents a considerable potential and bright future for improving effective interventions for AD.

CYP14 family in Caenorhabditis elegans: Mitochondrial function, detoxification, and lifespan

CYP-14 members of the Caenorhabditis elegans (C. elegans) Cytochrome P450 (CYP) enzyme family, plays important roles in mitochondrial dysfunction, detoxification, lipid metabolism, defense and lifespan regulation. The review identifies CYP-14 members: cyp-14A1, cyp-14A2, cyp-14A3, cyp-14A4, cyp-14A5 and their homology with human CYP families. Despite limited studies on C. elegans cyp-14 members, the findings unraveled their complex crosstalk between mitochondrial stress, detoxification mechanisms, and lifespan regulation, emphasizing the complexity of these interconnected pathways as well as how their regulation depends on environmental cues changes including pH, nutrients, ROS and chemical stressors. The review underscores the translational relevance to human health, shedding light on potential human homologues and their implications in age-related, metabolic and respiratory diseases. Among other genes, cyp-14A2 and cyp-14A4 predominate the mitochondrial function, heat resistance, lipid metabolism, detoxification and lifespan pathways. In conclusion, these insights pave the way for future research, offering promising avenues for therapeutic interventions targeting CYP-14 activity to address age-related diseases and promote healthy aging.

Lactiplantibacillus (Lactobacillus) plantarum as a Complementary Treatment to Improve Symptomatology in Neurodegenerative Disease: A Systematic Review of Open Access Literature

This systematic review addresses the use of Lactiplantibacillus (Lactobacillus) plantarum in the symptomatological intervention of neurodegenerative disease. The existence of gut microbiota dysbiosis has been associated with systemic inflammatory processes present in neurodegenerative disease, creating the opportunity for new treatment strategies. This involves modifying the strains that constitute the gut microbiota to enhance synaptic function through the gut-brain axis. Recent studies have evaluated the beneficial effects of the use of Lactiplantibacillus plantarum on motor and cognitive symptomatology, alone or in combination. This systematic review includes 20 research articles (n = 3 in human and n = 17 in animal models). The main result of this research was that the use of Lactiplantibacillus plantarum alone or in combination produced improvements in symptomatology related to neurodegenerative disease. However, one of the studies included reported negative effects after the administration of Lactiplantibacillus plantarum. This systematic review provides current and relevant information about the use of this probiotic in pathologies that present neurodegenerative processes such as Alzheimer's disease, Parkinson's disease and Multiple Sclerosis.

Tremendous Fidelity of Vitamin D3 in Age-related Neurological Disorders

Vitamin D3 (VD) is a secosteroid hormone and shows a pleiotropic effect in brain-related disorders where it regulates redox imbalance, inflammation, apoptosis, energy production, and growth factor synthesis. Vitamin D3's active metabolic form, 1,25-dihydroxy Vitamin D3 (1,25(OH)2D3 or calcitriol), is a known regulator of several genes involved in neuroplasticity, neuroprotection, neurotropism, and neuroinflammation. Multiple studies suggest that VD deficiency can be proposed as a risk factor for the development of several age-related neurological disorders. The evidence for low serum levels of 25-hydroxy Vitamin D3 (25(OH)D3 or calcidiol), the major circulating form of VD, is associated with an increased risk of Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), dementia, and cognitive impairment. Despite decades of evidence on low VD association with neurological disorders, the precise molecular mechanism behind its beneficial effect remains controversial. Here, we will be delving into the neurobiological importance of VD and discuss its benefits in different neuropsychiatric disorders. The focus will be on AD, PD, and HD as they share some common clinical, pathological, and epidemiological features. The central focus will be on the different attributes of VD in the aspect of its anti-oxidative, anti-inflammatory, anti-apoptotic, anti-cholinesterase activity, and psychotropic effect in different neurodegenerative diseases.

Role of ferroptosis pathways in neuroinflammation and neurological disorders: From pathogenesis to treatment

Ferroptosis is a newly discovered non-apoptotic and iron-dependent type of cell death. Ferroptosis mainly takes place owing to the imbalance of anti-oxidation and oxidation in the body. It is regulated via a number of factors and pathways both inside and outside the cell. Ferroptosis is closely linked with brain and various neurological disorders (NDs). In the human body, the brain contains the highest levels of polyunsaturated fatty acids, which are known as lipid peroxide precursors. In addition, there is also a connection of glutathione depletion and lipid peroxidation with NDs. There is growing evidence regarding the possible link between neuroinflammation and multiple NDs, such as Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, Huntington's disease, and stroke. Recent studies have demonstrated that disruptions of lipid reactive oxygen species (ROS), glutamate excitatory toxicity, iron homeostasis, and various other manifestations linked with ferroptosis can be identified in various neuroinflammation-mediated NDs. It has also been reported that damage-associated molecular pattern molecules including ROS are generated during the events of ferroptosis and can cause glial activation via activating neuroimmune pathways, which subsequently leads to the generation of various inflammatory factors that play a role in various NDs. This review summarizes the regulation pathways of ferroptosis, the link between ferroptosis as well as inflammation in NDs, and the potential of a range of therapeutic agents that can be used to target ferroptosis and inflammation in the treatment of neurological disorders.

Oxidative stress and ion channels in neurodegenerative diseases

Numerous neurodegenerative diseases result from altered ion channel function and mutations. The intracellular redox status can significantly alter the gating characteristics of ion channels. Abundant neurodegenerative diseases associated with oxidative stress have been documented, including Parkinson's, Alzheimer's, spinocerebellar ataxia, amyotrophic lateral sclerosis, and Huntington's disease. Reactive oxygen and nitrogen species compounds trigger posttranslational alterations that target specific sites within the subunits responsible for channel assembly. These alterations include the adjustment of cysteine residues through redox reactions induced by reactive oxygen species (ROS), nitration, and S-nitrosylation assisted by nitric oxide of tyrosine residues through peroxynitrite. Several ion channels have been directly investigated for their functional responses to oxidizing agents and oxidative stress. This review primarily explores the relationship and potential links between oxidative stress and ion channels in neurodegenerative conditions, such as cerebellar ataxias and Parkinson's disease. The potential correlation between oxidative stress and ion channels could hold promise for developing innovative therapies for common neurodegenerative diseases.

Oxidative stress in Alzheimer's disease: current knowledge of signaling pathways and therapeutics

Alzheimer's disease's pathophysiology is still a conundrum. Growing number of evidences have elucidated the involvement of oxidative stress in the pathology of AD rendering it a major target for therapeutic development. Reactive oxygen species (ROS) generated by altered mitochondrial function, dysregulated electron transport chain and other sources elevate aggregated Aβ and neurofibrillary tangles which further stimulating the production of ROS. Oxidative stress induced damage to lipids, proteins and DNA result in neuronal death which leads to AD. In addition, oxidative stress induces apoptosis that is triggered by the modulation of ERK1/2 and Nrf2 pathway followed by increased GSK-3β expression and decreased PP2A activity. Oxidative stress exaggerates disease condition by interfering with various signaling pathways like RCAN1, CREB/ERK, Nrf2, PP2A, NFκB and PI3K/Akt. Studies have reported the role of TNF-α in oxidative stress stimulation that has been regulated by drugs like etanercept increasing the level of anti-oxidants. Other drugs like pramipexole, memantine, carvedilol, and melatonin have been reported to activate CREB/RCAN1 and Nrf2 pathways. In line with this, epigallocatechin gallate and genistein also target Nrf2 and CREB pathway leading to activation of downstream pathways like ARE and Keap1 which ameliorate oxidative stress condition. Donepezil and resveratrol reduce oxidative stress and activate AMPK pathway along with PP2A activation thus promoting tau dephosphorylation and neuronal survival. This study describes in detail the role of oxidative stress in AD, major signaling pathways involving oxidative stress induced AD and drugs under development targeting these pathways which may aid in therapeutic advances for AD.

Docosahexaenoic Acid-Acylated Astaxanthin Monoester Ameliorates Amyloid-β Pathology and Neuronal Damage by Restoring Autophagy in Alzheimer's Disease Models

SCOPE

Astaxanthin (AST) is ubiquitous in aquatic foods and microorganisms. The study previously finds that docosahexaenoic acid-acylated AST monoester (AST-DHA) improves cognitive function in Alzheimer's disease (AD), although the underlying mechanism remains unclear. Moreover, autophagy is reportedly involved in amyloid-β (Aβ) clearance and AD pathogenesis. Therefore, this study aims to evaluate the preventive effect of AST-DHA and elucidates the mechanism of autophagy modulation in Aβ pathology.

METHODS AND RESULTS

In the cellular AD model, AST-DHA significantly reduces toxic Aβ1-42 levels and alleviated the accumulation of autophagic markers (LC3II/I and p62) in Aβ25-35 -induced SH-SY5Y cells. Notably, AST-DHA restores the autophagic flux in SH-SY5YmRFP-GFP-LC3 cells. In APP/PS1 mice, a 3-month dietary supplementation of AST-DHA exceeded free-astaxanthin (F-AST) capacity to increase hippocampal and cortical autophagy. Mechanistically, AST-DHA restores autophagy by activating the ULK1 signaling pathway and restoring autophagy-lysosome fusion. Moreover, AST-DHA relieves ROS production and mitochondrial stress affecting autophagy in AD. As a favorable outcome of restored autophagy, AST-DHA mitigates cerebral Aβ and p-Tau deposition, ultimately improving neuronal function.

CONCLUSION

The findings demonstrate that AST-DHA can rectify autophagic impairment in AD, and confer neuroprotection in Aβ-related pathology, which supports the future application of AST as an autophagic inducer for maintaining brain health.

Investigating Bacopa monnieri L. Therapeutic Potential for the Treatment of Neurological Diseases

The popular perennial creeping plant known as Bacopa monnieri (also known as Brahmi) is being utilized in the Indian Ayurvedic medicine practice. It has a variety of bioactive phytoconstituents that have been used therapeutically to treat a number of serious illnesses. Ancient Vedic scholars used this herb because of its pharmacological effects, particularly as a nerve booster and nootropic supporter. However, it is vital to comprehend the active phytochemical components of Bacopa monnieri extract (BME) and their molecular mechanisms in order to better grasp the effect of BME on neurological illnesses and diseases. Understanding its active phytochemical constituents and their molecular processes is essential. Numerous clinical investigations indicated that BME may have neuroprotective benefits, so it is worthwhile to re-evaluate this wellknown plant. Here, we focused on neurological problems as we examined the pharmacological and phytochemical characteristics of BME. For their effective usage in neuroprotection and cognition, many clinical concerns and the synergistic potential of Bacopa extract have been investigated. Alzheimer's disease is a neurological condition caused by the production of reactive oxygen species, which also causes amyloid-beta (Aβ) and tau protein aggregation and increases neuro-inflammation and neurotoxicity. Our review offers a more indepth molecular understanding of the neuroprotective functions of BME, which can also be connected to its therapeutic management of neurological illnesses and cognitive-improving effects.

Iridium metal complex targeting oxidation resistance 1 protein attenuates spinal cord injury by inhibiting oxidative stress-associated reactive oxygen species

Oxidative stress is a key factor leading to profound neurological deficits following spinal cord injury (SCI). In this study, we present the development and potential application of an iridium (iii) complex, (CpxbiPh) Ir (N^N) Cl, where CpxbiPh represents 1-biphenyl-2,3,4,5-tetramethyl cyclopentadienyl, and N^N denotes 2-(3-(4-nitrophenyl)-1H-1,2,4-triazol-5-yl) pyridine chelating agents, to address this challenge through a mechanism governed by the regulation of an antioxidant protein. This iridium complex, IrPHtz, can modulate the Oxidation Resistance 1 (OXR1) protein levels within spinal cord tissues, thus showcasing its antioxidative potential. By eliminating reactive oxygen species (ROS) and preventing apoptosis, the IrPHtz demonstrated neuroprotective and neural healing characteristics on injured neurons. Our molecular docking analysis unveiled the presence of π stacking within the IrPHtz-OXR1 complex, an interaction that enhanced OXR1 expression, subsequently diminishing oxidative stress, thwarting neuroinflammation, and averting neuronal apoptosis. Furthermore, in in vivo experimentation with SCI-afflicted mice, IrPHtz was efficacious in shielding spinal cord neurons, promoting their regrowth, restoring electrical signaling, and improving motor performance. Collectively, these findings underscore the potential of employing the iridium metal complex in a novel, protein-regulated antioxidant strategy, presenting a promising avenue for therapeutic intervention in SCI.

Protective function of StAR in amyloid-β accumulated hippocampal neurotoxicity and neurosteroidogenesis: Mechanistic insights into Alzheimer's disease

The steroidogenic acute regulatory (StAR) protein principally mediates steroid hormone biosynthesis by governing the transport of intramitochondrial cholesterol. Neurosteroids progressively decrease during aging, the key risk factor for Alzheimer's disease (AD), which is triggered by brain-region specific accumulation of amyloid beta (Aβ) precursor protein (APP), a key pathological factor. We demonstrate that hippocampal neuronal cells overexpressing wild-type (WtAPP) and mutant APP (mAPP) plasmids, conditions mimetic to AD, resulted in decreases in StAR mRNA, free cholesterol, and pregnenolone levels. The magnitude of suppression of the steroidogenic response was more pronounced with mAPP than that of WtAPP. While mAPP-waned assorted anomalies correlate to AD pathology, deterioration of APP/Aβ laden StAR expression and neurosteroid biosynthesis was enhanced by retinoid signaling. An abundance of mitochondrially targeted StAR expression partially restored APP/Aβ accumulated diverse neurodegenerative vulnerabilities. Immunofluorescence analyses revealed that overexpression of StAR diminishes mAPP provoked Aβ aggregation. Co-expression of StAR and mAPP in hippocampal neurons substantially reversed the declines in mAPP mediated cell survival, mitochondrial oxygen consumption rate, and ATP production. Concurrently, induction of mAPP induced Aβ loading showed an increase in cholesterol esters, but decrease in free cholesterol, concomitant with pregnenolone biosynthesis, events that were inversely regulated by StAR. Moreover, retinoid signaling was found to augment cholesterol content for facilitating neurosteroid biosynthesis in an AD mimetic condition. These findings provide novel insights into the molecular events by which StAR acts to protect mAPP-induced hippocampal neurotoxicity, mitochondrial dysfunction, and neurosteroidogenesis, and these measures are fundamental for ameliorating and/or delaying dementia in individuals with AD.

A review of therapeutic impacts of saffron (Crocus sativus L.) and its constituents

Application of herbal medicines in the treatment of diseases is in the center of attention of medical scientific societies. Saffron (Cricus sativus L.) is a medicinal plant belonging to the Iridaceae family with different therapeutic properties. The outcomes of human and animal experiments indicate that therapeutic impacts of saffron and its constituents, crocin, crocetin, and safranal, mainly are mediated via inhibiting the inflammatory reactions and scavenging free radicals. It has been suggested that saffron and crocin extracted from it also up-regulate the expression of sirtuin 1 (SIRT1) and nuclear factor erythroid 2-related factor 2 (Nrf2), down-regulate nuclear factor kappa B (NF-κB) signaling pathway and untimely improve the body organs dysfunction. Inhibition of inducible nitric oxide synthase and cyclooxygenase-2 (COX2) also is attributed to crocin. The current review narrates the therapeutic effects of saffron and its constituents on various body systems through looking for the scientific databases including Web of Science, PubMed, Scopus, and Google Scholar from the beginning of 2010 until the end of 2022.

Role of microglial metabolic reprogramming in Parkinson's disease

Parkinson's disease (PD) is a common age-related neurodegenerative disorder characterized by damage to nigrostriatal dopaminergic neurons. Key pathogenic mechanisms underlying PD include alpha-synuclein misfolding and aggregation, impaired protein clearance, mitochondrial dysfunction, oxidative stress, and neuroinflammation. However, to date, no study has confirmed the specific pathogenesis of PD. Similarly, current PD treatment methods still have shortcomings. Although some emerging therapies have proved effective for PD, the specific mechanism still needs further clarification. Metabolic reprogramming, a term first proposed by Warburg, is applied to the metabolic energy characteristics of tumor cells. Microglia have similar metabolic characteristics. Pro-inflammatory M1 type and anti-inflammatory M2 type are the two types of activated microglia, which exhibit different metabolic patterns in glucose, lipid, amino acid, and iron metabolism. Additionally, mitochondrial dysfunction may be involved in microglial metabolic reprogramming by activating various signaling mechanisms. Functional changes in microglia resulting from metabolic reprogramming can cause changes in the brain microenvironment, thus playing an important role in neuroinflammation or tissue repair. The involvement of microglial metabolic reprogramming in PD pathogenesis has been confirmed. Neuroinflammation and dopaminergic neuronal death can effectively be reduced by inhibiting certain metabolic pathways in M1 microglia or reverting M1 cells to the M2 phenotype. This review summarizes the relationship between microglial metabolic reprogramming and PD and provides strategies for PD treatment.

Mitochondria-Targeted Delivery Strategy of Dual-Loaded Liposomes for Alzheimer's Disease Therapy

Liposomes modified with tetradecyltriphenylphosphonium bromide with dual loading of α-tocopherol and donepezil hydrochloride were successfully designed for intranasal administration. Physicochemical characteristics of cationic liposomes such as the hydrodynamic diameter, zeta potential, and polydispersity index were within the range from 105 to 115 nm, from +10 to +23 mV, and from 0.1 to 0.2, respectively. In vitro release curves of donepezil hydrochloride were analyzed using the Korsmeyer-Peppas, Higuchi, First-Order, and Zero-Order kinetic models. Nanocontainers modified with cationic surfactant statistically better penetrate into the mitochondria of rat motoneurons. Imaging of rat brain slices revealed the penetration of nanocarriers into the brain. Experiments on transgenic mice with an Alzheimer's disease model (APP/PS1) demonstrated that the intranasal administration of liposomes within 21 days resulted in enhanced learning abilities and a reduction in the formation rate of Aβ plaques in the entorhinal cortex and hippocampus of the brain.

The heterogeneity of Parkinson's disease

The heterogeneity of Parkinson's disease (PD), i.e. the various clinical phenotypes, pathological findings, genetic predispositions and probably also the various implicated pathophysiological pathways pose a major challenge for future research projects and therapeutic trail design. We outline several pathophysiological concepts, pathways and mechanisms, including the presumed roles of α-synuclein misfolding and aggregation, Lewy bodies, oxidative stress, iron and melanin, deficient autophagy processes, insulin and incretin signaling, T-cell autoimmunity, the gut-brain axis and the evidence that microbial (viral) agents may induce molecular hallmarks of neurodegeneration. The hypothesis is discussed, whether PD might indeed be triggered by exogenous (infectious) agents in susceptible individuals upon entry via the olfactory bulb (brain first) or the gut (body-first), which would support the idea that disease mechanisms may change over time. The unresolved heterogeneity of PD may have contributed to the failure of past clinical trials, which attempted to slow the course of PD. We thus conclude that PD patients need personalized therapeutic approaches tailored to specific phenomenological and etiologic subtypes of disease.

Age-Dependent Alterations in Platelet Mitochondrial Respiration

Mitochondrial dysfunction is an important cellular hallmark of aging and neurodegeneration. Platelets are a useful model to study the systemic manifestations of mitochondrial dysfunction. To evaluate the age dependence of mitochondrial parameters, citrate synthase activity, respiratory chain complex activity, and oxygen consumption kinetics were assessed. The effect of cognitive impairment was examined by comparing the age dependence of mitochondrial parameters in healthy individuals and those with neuropsychiatric disease. The study found a significant negative slope of age-dependence for both the activity of individual mitochondrial enzymes (citrate synthase and complex II) and parameters of mitochondrial respiration in intact platelets (routine respiration, maximum capacity of electron transport system, and respiratory rate after complex I inhibition). However, there was no significant difference in the age-related changes of mitochondrial parameters between individuals with and without cognitive impairment. These findings highlight the potential of measuring mitochondrial respiration in intact platelets as a means to assess age-related mitochondrial dysfunction. The results indicate that drugs and interventions targeting mitochondrial respiration may have the potential to slow down or eliminate certain aging and neurodegenerative processes. Mitochondrial respiration in platelets holds promise as a biomarker of aging, irrespective of the degree of cognitive impairment.

Escalating Bi-Directional Feedback Loops between Proinflammatory Microglia and Mitochondria in Ageing and Post-Diagnosis of Parkinson's Disease

Parkinson's disease (PD) is a chronic and progressive age-related neurodegenerative disease affecting up to 3% of the global population over 65 years of age. Currently, the underlying physiological aetiology of PD is unknown. However, the diagnosed disorder shares many common non-motor symptoms associated with ageing-related neurodegenerative disease progression, such as neuroinflammation, microglial activation, neuronal mitochondrial impairment, and chronic autonomic nervous system dysfunction. Clinical PD has been linked to many interrelated biological and molecular processes, such as escalating proinflammatory immune responses, mitochondrial impairment, lower adenosine triphosphate (ATP) availability, increasing release of neurotoxic reactive oxygen species (ROS), impaired blood brain barrier integrity, chronic activation of microglia, and damage to dopaminergic neurons consistently associated with motor and cognitive decline. Prodromal PD has also been associated with orthostatic hypotension and many other age-related impairments, such as sleep disruption, impaired gut microbiome, and constipation. Thus, this review aimed to present evidence linking mitochondrial dysfunction, including elevated oxidative stress, ROS, and impaired cellular energy production, with the overactivation and escalation of a microglial-mediated proinflammatory immune response as naturally occurring and damaging interlinked bidirectional and self-perpetuating cycles that share common pathological processes in ageing and PD. We propose that both chronic inflammation, microglial activation, and neuronal mitochondrial impairment should be considered as concurrently influencing each other along a continuum rather than as separate and isolated linear metabolic events that affect specific aspects of neural processing and brain function.

Mitochondrial Bioenergy in Neurodegenerative Disease: Huntington and Parkinson

Strong evidence suggests a correlation between degeneration and mitochondrial deficiency. Typical cases of degeneration can be observed in physiological phenomena (i.e., ageing) as well as in neurological neurodegenerative diseases and cancer. All these pathologies have the dyshomeostasis of mitochondrial bioenergy as a common denominator. Neurodegenerative diseases show bioenergetic imbalances in their pathogenesis or progression. Huntington's chorea and Parkinson's disease are both neurodegenerative diseases, but while Huntington's disease is genetic and progressive with early manifestation and severe penetrance, Parkinson's disease is a pathology with multifactorial aspects. Indeed, there are different types of Parkinson/Parkinsonism. Many forms are early-onset diseases linked to gene mutations, while others could be idiopathic, appear in young adults, or be post-injury senescence conditions. Although Huntington's is defined as a hyperkinetic disorder, Parkinson's is a hypokinetic disorder. However, they both share a lot of similarities, such as neuronal excitability, the loss of striatal function, psychiatric comorbidity, etc. In this review, we will describe the start and development of both diseases in relation to mitochondrial dysfunction. These dysfunctions act on energy metabolism and reduce the vitality of neurons in many different brain areas.

Neuroprotective Effects of a Novel Tetrapeptide SGGY from Walnut against H2O2-Stimulated Oxidative Stress in SH-SY5Y Cells: Possible Involved JNK, p38 and Nrf2 Signaling Pathways

SGGY, an antioxidant tetrapeptide identified from walnut protein hydrolysate in our previous study, has been suggested to possess the potential to alleviate oxidative stress in cells. In this paper, the neuroprotective effects of SGGY on H2O2-stimulated oxidative stress in SH-SY5Y cells and the underlying mechanisms were investigated. Results showed that SGGY alleviated H2O2-induced oxidative stress by decreasing the intracellular reactive oxygen species (ROS) level and altering the mitochondrial membrane potential (MMP), thereby inhibiting apoptosis and increasing cell viability. SGGY significantly restored antioxidant enzyme activities and reduced malondialdehyde (MDA) content accordingly. Moreover, SGGY promoted the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and suppressed the H2O2-induced activation of JNK and p38 mitogen-activated protein kinases (MAPKs). Taken together, these results suggested that SGGY protected SH-SY5Y cells from H2O2-provoked oxidative stress by enhancing the ability of cellular antioxidant defense, and the possible mechanism involved MAPKs and Nrf2 signaling pathways.

Mitochondrial Transplantation in Mitochondrial Medicine: Current Challenges and Future Perspectives

Mitochondrial diseases (MDs) are inherited genetic conditions characterized by pathogenic mutations in nuclear DNA (nDNA) or mitochondrial DNA (mtDNA). Current therapies are still far from being fully effective and from covering the broad spectrum of mutations in mtDNA. For example, unlike heteroplasmic conditions, MDs caused by homoplasmic mtDNA mutations do not yet benefit from advances in molecular approaches. An attractive method of providing dysfunctional cells and/or tissues with healthy mitochondria is mitochondrial transplantation. In this review, we discuss what is known about intercellular transfer of mitochondria and the methods used to transfer mitochondria both in vitro and in vivo, and we provide an outlook on future therapeutic applications. Overall, the transfer of healthy mitochondria containing wild-type mtDNA copies could induce a heteroplasmic shift even when homoplasmic mtDNA variants are present, with the aim of attenuating or preventing the progression of pathological clinical phenotypes. In summary, mitochondrial transplantation is a challenging but potentially ground-breaking option for the treatment of various mitochondrial pathologies, although several questions remain to be addressed before its application in mitochondrial medicine.

Fullerenols Prevent Neuron Death and Reduce Oxidative Stress in Drosophila Huntington's Disease Model

Huntington's disease (HD) is one of the human neurodegenerative diseases for which there is no effective treatment. Therefore, there is a strong demand for a novel neuroprotective agent that can alleviate its course. Fullerene derivatives are considered to be such agents; however, they need to be comprehensively investigated in model organisms. In this work, neuroprotective activity of C₆₀(OH)₃₀ and C₁₂₀O(OH)₄₄ fullerenols was analyzed for the first time in a Drosophila transgenic model of HD. Lifespan, behavior, oxidative stress level and age-related neurodegeneration were assessed in flies with the pathogenic Huntingtin protein expression in nerve cells. Feed supplementation with hydroxylated C₆₀ fullerene and C₁₂₀O dimer oxide molecules was shown to diminish the oxidative stress level and neurodegenerative processes in the flies' brains. Thus, fullerenes displayed neuroprotective activity in this model.