Lipid peroxidation in neurodegeneration

Phospholipidomics in Clinical Trials for Brain Disorders: Advancing our Understanding and Therapeutic Potentials

Phospholipidomics is a specialized branch of lipidomics that focuses on the characterization and quantification of phospholipids. By using sensitive analytical techniques, phospholipidomics enables researchers to better understand the metabolism and activities of phospholipids in brain disorders such as Alzheimer's and Parkinson's diseases. In the brain, identifying specific phospholipid biomarkers can offer valuable insights into the underlying molecular features and biochemistry of these diseases through a variety of sensitive analytical techniques. Phospholipidomics has emerged as a promising tool in clinical studies, with immense potential to advance our knowledge of neurological diseases and enhance diagnosis and treatment options for patients. In the present review paper, we discussed numerous applications of phospholipidomics tools in clinical studies, with a particular focus on the neurological field. By exploring phospholipids' functions in neurological diseases and the potential of phospholipidomics in clinical research, we provided valuable insights that could aid researchers and clinicians in harnessing the full prospective of this innovative practice and improve patient outcomes by providing more potent treatments for neurological diseases.

Aspartame use and Parkinson's disease: review of associated effects on neurotransmitters, oxidative stress, and cognition

Objective: The purpose of this review was to assess the current evidence regarding the associated physiological and cognitive effects of aspartame (APM) consumption and Parkinson's Disease (PD).

METHODS

A total of 32 studies demonstrating effects of APM on monoamine deficiencies, oxidative stress, and cognitive changes were reviewed.

RESULTS

Multiple studies demonstrated decreased brain dopamine, decreased brain norepinephrine, increased oxidative stress, increased lipid peroxidation, and decreased memory function in rodents after APM use. In addition, PD animal models have been found to be more sensitive to the effects of APM.

DISCUSSION

Overall, studies of APM use over time yielded more consistent results; however, no study has examined long-term effects on APM in human PD patients. Based on the current evidence, long-term human based observational research is needed to further investigate the potential effect of APM on PD.

Mitochondria-targeted BODIPY dyes for small molecule recognition, bio-imaging and photodynamic therapy

Mitochondria are essential for a diverse array of biological functions. There is increasing research focus on developing efficient tools for mitochondria-targeted detection and treatment. BODIPY dyes, known for their structural versatility and excellent spectroscopic properties, are being actively explored in this context. Numerous studies have focused on developing innovative BODIPYs that utilize optical signals for imaging mitochondria. This review presents a comprehensive overview of the progress made in this field, aiming to investigate mitochondria-related biological events. It covers key factors such as design strategies, spectroscopic properties, and cytotoxicity, as well as mechanism to facilitate their future application in organelle imaging and targeted therapy. This work is anticipated to provide valuable insights for guiding future development and facilitating further investigation into mitochondria-related biological sensing and phototherapy.

Arginine vasopressin induces ferroptosis to promote heart failure via activation of the V1aR/CaN/NFATC3 pathway

Arginine vasopressin (AVP) is a key contributor to heart failure (HF), but the underlying mechanisms remain unclear. In the present study, a mouse model of HF and human cardiomyocyte (HCM) cells treated with dDAVP are generated in vivo and in vitro, respectively. Hematoxylin and eosin (HE) staining is used to evaluate the morphological changes in the myocardial tissues. A colorimetric method is used to measure the iron concentration, Fe 2+ concentration and malondialdehyde (MDA) level. Western blot analysis is used to examine the protein levels of the V1a receptor (V1aR), calcineurin (CaN), nuclear factor of activated T cells isoform C3 (NFATC3), glutathione peroxidase 4 (GPX4) and acyl-CoA synthase long chain family member 4 (ACSL4). Immunoprecipitation (IP) and luciferase reporter assays are performed to determine the interaction between NFATC3 and ACSL4. Both in vivo and in vitro experiments reveal that the V1aR-CaN-NFATC3 signaling pathway and ferroptosis are upregulated in HFs, which are verified by the elevated protein levels of V1aR, CaN, NFATC3 and ACSL4; reduced GPX4 protein level; and enhanced Fe 2+ and MDA levels. We further find that inhibiting NFATC3 by suppressing the V1aR/CaN/NFATC3 pathway via V1aR/CaN inhibitors or sh-NFATC3 not only alleviates HF but also inhibits AVP-induced ferroptosis. Mechanistically, sh-NFATC3 significantly reverses the increase in AVP-induced ACSL4 protein level, Fe 2+ concentration, and MDA level by directly interacting with ACSL4. Our results demonstrate that AVP enhances ACSL4 expression by activating the V1aR/CaN/NFATC3 pathway to induce ferroptosis, thus contributing to HF. This study may lead to the proposal of a novel therapeutic strategy for HF.

Effects of crocin on inflammatory biomarkers and mental health status in patients with multiple sclerosis: A randomized, double-blinded clinical trial

BACKGROUND

Multiple sclerosis (MS), as a demyelinating disease correlated with inflammation and oxidative stress, affects the central nervous system and causes a wide range of complications, including psychiatric disorders. Considering the anti-inflammatory and antioxidant properties associated with the bioactive components of saffron, such as crocin (trans-crocetin bis(β-d-gentiobiosyl) ester), and their potential impact on ameliorating psychiatric symptoms, our study aimed to investigate the effect of crocin on biomarkers of inflammation, oxidative stress, and mental health, e.g., depression and anxiety in individuals with MS.

METHOD

Patients with MS were randomized into two groups, taking either 15 mg crocin tablets twice a day (n = 25; 30 mg/day) or placebo tablets (n = 25) for 8 weeks. The valid and reliable Beck depression and anxiety scale questionnaire was recorded, and fasting blood samples were collected to measure biomarkers, including high-sensitivity C-reactive protein (hs-CRP), malondialdehyde (MDA), and nitric oxide (NO) at baseline and week 8 following the intervention.

RESULTS

The data analysis using ANCOVA showed that supplementation with crocin for 8 weeks significantly lowered hs-CRP levels (p-value= 0.01). In addition, within-group comparisons showed crocin significantly decreased anxiety (p-value= 0.01). However, crocin did not affect serum MDA and NO after 8 weeks of intervention.

CONCLUSION

Our findings suggest that crocin may keep promise in attenuating inflammation, evidenced by reducing hs-CRP in patients with MS. However, supplementation for 8 weeks may not be sufficient to improve mental health, and future clinical studies with higher sample sizes and various doses and durations are recommended.

New Insights into Oxidative Stress and Inflammatory Response in Neurodegenerative Diseases

Oxidative stress (OS) and inflammation are two important and well-studied pathological hallmarks of neurodegenerative diseases (NDDs). Due to elevated oxygen consumption, the high presence of easily oxidizable polyunsaturated fatty acids and the weak antioxidant defenses, the brain is particularly vulnerable to oxidative injury. Uncertainty exists over whether these deficits contribute to the development of NDDs or are solely a consequence of neuronal degeneration. Furthermore, these two pathological hallmarks are linked, and it is known that OS can affect the inflammatory response. In this review, we will overview the last findings about these two pathways in the principal NDDs. Moreover, we will focus more in depth on amyotrophic lateral sclerosis (ALS) to understand how anti-inflammatory and antioxidants drugs have been used for the treatment of this still incurable motor neuron (MN) disease. Finally, we will analyze the principal past and actual clinical trials and the future perspectives in the study of these two pathological mechanisms.

Metformin: The Winding Path from Understanding Its Molecular Mechanisms to Proving Therapeutic Benefits in Neurodegenerative Disorders

Metformin, a widely prescribed medication for type 2 diabetes, has garnered increasing attention for its potential neuroprotective properties due to the growing demand for treatments for Alzheimer's, Parkinson's, and motor neuron diseases. This review synthesizes experimental and clinical studies on metformin's mechanisms of action and potential therapeutic benefits for neurodegenerative disorders. A comprehensive search of electronic databases, including PubMed, MEDLINE, Embase, and Cochrane library, focused on key phrases such as "metformin", "neuroprotection", and "neurodegenerative diseases", with data up to September 2023. Recent research on metformin's glucoregulatory mechanisms reveals new molecular targets, including the activation of the LKB1-AMPK signaling pathway, which is crucial for chronic administration of metformin. The pleiotropic impact may involve other stress kinases that are acutely activated. The precise role of respiratory chain complexes (I and IV), of the mitochondrial targets, or of the lysosomes in metformin effects remains to be established by further research. Research on extrahepatic targets like the gut and microbiota, as well as its antioxidant and immunomodulatory properties, is crucial for understanding neurodegenerative disorders. Experimental data on animal models shows promising results, but clinical studies are inconclusive. Understanding the molecular targets and mechanisms of its effects could help design clinical trials to explore and, hopefully, prove its therapeutic effects in neurodegenerative conditions.

Molecular mechanism and potential therapeutic targets of necroptosis and ferroptosis in Alzheimer's disease

Alzheimer's disease (AD), a neurodegenerative condition, is defined by neurofibrillary tangles, amyloid plaques, and gradual cognitive decline. Regardless of the advances in understanding AD's pathogenesis and progression, its causes are still contested, and there are currently no efficient therapies for the illness. The post-mortem analyses revealed widespread neuronal loss in multiple brain regions in AD, evidenced by a decrease in neuronal density and correlated with the disease's progression and cognitive deterioration. AD's neurodegeneration is complicated, and different types of neuronal cell death, alone or in combination, play crucial roles in this process. Recently, the involvement of non-apoptotic programmed cell death in the neurodegenerative mechanisms of AD has received a lot of attention. Aberrant activation of necroptosis and ferroptosis, two newly discovered forms of regulated non-apoptotic cell death, is thought to contribute to neuronal cell death in AD. In this review, we first address the main features of necroptosis and ferroptosis, cellular signaling cascades, and the mechanisms involved in AD pathology. Then, we discuss the latest therapies targeting necroptosis and ferroptosis in AD animal/cell models and human research to provide vital information for AD treatment.

Patient-Derived Cellular Models for Polytarget Precision Medicine in Pantothenate Kinase-Associated Neurodegeneration

The term neurodegeneration with brain iron accumulation (NBIA) brings together a broad set of progressive and disabling neurological genetic disorders in which iron is deposited preferentially in certain areas of the brain. Among NBIA disorders, the most frequent subtype is pantothenate kinase-associated neurodegeneration (PKAN) caused by pathologic variants in the PANK2 gene codifying the enzyme pantothenate kinase 2 (PANK2). To date, there are no effective treatments to stop the progression of these diseases. This review discusses the utility of patient-derived cell models as a valuable tool for the identification of pharmacological or natural compounds for implementing polytarget precision medicine in PKAN. Recently, several studies have described that PKAN patient-derived fibroblasts present the main pathological features associated with the disease including intracellular iron overload. Interestingly, treatment of mutant cell cultures with various supplements such as pantothenate, pantethine, vitamin E, omega 3, α-lipoic acid L-carnitine or thiamine, improved all pathophysiological alterations in PKAN fibroblasts with residual expression of the PANK2 enzyme. The information provided by pharmacological screenings in patient-derived cellular models can help optimize therapeutic strategies in individual PKAN patients.

Impact of Polyphenols on Inflammatory and Oxidative Stress Factors in Diabetes Mellitus: Nutritional Antioxidants and Their Application in Improving Antidiabetic Therapy

Diabetes mellitus is a chronic metabolic disorder characterized by hyperglycaemia and oxidative stress. Oxidative stress plays a crucial role in the development and progression of diabetes and its complications. Nutritional antioxidants derived from dietary sources have gained significant attention due to their potential to improve antidiabetic therapy. This review will delve into the world of polyphenols, investigating their origins in plants, metabolism in the human body, and relevance to the antioxidant mechanism in the context of improving antidiabetic therapy by attenuating oxidative stress, improving insulin sensitivity, and preserving β-cell function. The potential mechanisms of, clinical evidence for, and future perspectives on nutritional antioxidants as adjuvant therapy in diabetes management are discussed.

Lipid peroxidation in osteoarthritis: focusing on 4-hydroxynonenal, malondialdehyde, and ferroptosis

Osteoarthritis (OA) is a multifactorial and increasingly prevalent degenerative disease that affects the whole joint. The pathogenesis of OA is poorly understood and there is a lack of therapeutic interventions to reverse the pathological process of this disease. Accumulating studies have shown that the overproduction of reactive oxygen species (ROS) and ROS-induced lipid peroxidation are involved in the pathogenesis of OA. 4-Hydroxy-2-nonenal (4-HNE) and malondialdehyde (MDA) have received considerable attention for their role in cartilage degeneration and subchondral bone remodeling during OA development. Ferroptosis is a form of cell death characterized by a lack of control of membrane lipid peroxidation and recent studies have suggested that chondrocyte ferroptosis contributes to OA progression. In this review, we aim to discuss lipid peroxidation-derived 4-HNE and MDA in the progression of OA. In addition, the therapeutic potential for OA by controlling the accumulation of lipid peroxidation and inhibiting chondrocyte ferroptosis are discussed.

Lipid Peroxidation and Antioxidant Protection

Lipid peroxidation (LP) is the most important type of oxidative-radical damage in biological systems, owing to its interplay with ferroptosis and to its role in secondary damage to other biomolecules, such as proteins. The chemistry of LP and its biological consequences are reviewed with focus on the kinetics of the various processes, which helps understand the mechanisms and efficacy of antioxidant strategies. The main types of antioxidants are discussed in terms of structure-activity rationalization, with focus on mechanism and kinetics, as well as on their potential role in modulating ferroptosis. Phenols, pyri(mi)dinols, antioxidants based on heavy chalcogens (Se and Te), diarylamines, ascorbate and others are addressed, along with the latest unconventional antioxidant strategies based on the double-sided role of the superoxide/hydroperoxyl radical system.

Ultrasonic-assisted extraction, analysis and properties of mung bean peel polysaccharide

In order to improve the yield of mung bean peel polysaccharide, on the basis of single-factor experiments, the ultrasonic assisted extraction conditions were optimized by response surface methodology (RSM). The results showed that under the conditions of material-liquid ratio of 1: 40, temperature 77 °C, ultrasonic power 216 W and extraction time 47 min, the extraction rate of mung bean peel polysaccharide was the best, which was 2.55 %. The extracted polysaccharide was phosphorylated and its antioxidant activity in vitro was studied. The results suggested that the modified polysaccharide had a significant scavenging effect on hydroxyl radicals and enhanced the ability of anti-lipid peroxidation, which offered ideas and methods for the development and application of mung bean peel polysaccharide.

Is metformin neuroprotective against diabetes mellitus-induced neurodegeneration? An updated graphical review of molecular basis

Diabetes mellitus (DM) is a metabolic disease that activates several molecular pathways involved in neurodegenerative disorders. Metformin, an anti-hyperglycemic drug used for treating DM, has the potential to exert a significant neuroprotective role against the detrimental effects of DM. This review discusses recent clinical and laboratory studies investigating the neuroprotective properties of metformin against DM-induced neurodegeneration and the roles of various molecular pathways, including mitochondrial dysfunction, oxidative stress, inflammation, apoptosis, and its related cascades. A literature search was conducted from January 2000 to December 2022 using multiple databases including Web of Science, Wiley, Springer, PubMed, Elsevier Science Direct, Google Scholar, the Core Collection, Scopus, and the Cochrane Library to collect and evaluate peer-reviewed literature regarding the neuroprotective role of metformin against DM-induced neurodegenerative events. The literature search supports the conclusion that metformin is neuroprotective against DM-induced neuronal cell degeneration in both peripheral and central nervous systems, and this effect is likely mediated via modulation of oxidative stress, inflammation, and cell death pathways.

Prognostic Value of Malondialdehyde (MDA) in the Temporal Progression of Chronic Spinal Cord Injury

Background: Oxidative stress is a major signature of spinal cord injury (SCI). The altered levels of various oxidative stress markers have been demonstrated in acute and chronic SCI. However, the variation of these markers in patients with chronic SCI depending on the time since the initial injury has not been explored yet. Objective: Our aim was to measure plasma levels of malondialdehyde (MDA), a marker of lipid peroxidation in patients with SCI stratified in different periods of suffering the injury (0–5 years, 5–10 years, and more than 10 years). Patients and methods: This cross-sectional study enrolled patients with SCI (N = 105) from different periods of the lesion and healthy control (HC) subjects (N = 38): short period (SCI SP, N = 31, time of evolution less than 5 years); early chronic (SCI ECP, N = 32, time of evolution 5–15 years); and late chronic (SCI LCP, N = 42, time of evolution more than 15 years). The plasma levels of MDA were measured using a commercially available colorimetric assay. Results: Patients with SCI had significantly higher plasma levels of MDA than HC subjects. Receiver operating characteristic (ROC) curve analysis for plasma MDA levels in patients with SCI demonstrated areas under the curve (AUC) of 1 (HC vs. SCI-SP); 0.998 (HC vs. SCI-ECP); and 0.964 (HC vs. SCI-LCP). Additionally, three ROC curves were used to compare the different concentrations of MDA between the subgroups of patients with SCI, and the resulting AUCs were: 0.896 (SCI-SP vs. SCI-ECP); 0.840 (SCI-ECP vs. SCI-LCP); and 0.979 (SCI-SP vs. SCI-LCP). Conclusion: Plasma concentration of MDA can be considered as an oxidative stress biomarker to assess the prognosis of SCI in chronic stages.

Biomarkers of oxidative stress and reproductive complications

Oxidative stress is the result of an imbalance between the formation of reactive oxygen species (ROS) and the levels of enzymatic and non-enzymatic antioxidants. The assessment of biological redox status is performed by the use of oxidative stress biomarkers. An oxidative stress biomarker is defined as any physical structure or process or chemical compound that can be assessed in a living being (in vivo) or in solid or fluid parts thereof (in vitro), the determination of which is a reproducible and reliable indicator of oxidative stress. The use of oxidative stress biomarkers allows early identification of the risk of developing diseases associated with this process and also opens up possibilities for new treatments. At the end of the last century, interest in oxidative stress biomarkers began to grow, due to evidence of the association between the generation of free radicals and various pathologies. Up to now, a significant number of studies have been carried out to identify and apply different oxidative stress biomarkers in clinical practice. Among the most important oxidative stress biomarkers, it can be mentioned the products of oxidative modifications of lipids, proteins, nucleic acids, and uric acid as well as the measurement of the total antioxidant capacity of fluids in the human body. In this review, we aim to present recent advances and current knowledge on the main biomarkers of oxidative stress, including the discovery of new biomarkers, with emphasis on the various reproductive complications associated with variations in oxidative stress levels.

Trafficking of oxidative stress-generated lipid hydroperoxides: pathophysiological implications

Lipid hydroperoxides (LOOHs) are reactive intermediates that arise during peroxidation of unsaturated phospholipids, glycolipids and cholesterol in biological membranes and lipoproteins. Non-physiological lipid peroxidation (LPO) typically occurs under oxidative stress conditions associated with pathologies such as atherogenesis, neurodegeneration, and carcinogenesis. As key intermediates in the LPO process, LOOHs are susceptible to one-electron versus two-electron reductive turnover, the former exacerbating membrane or lipoprotein damage/dysfunction and the latter diminishing it. A third possible LOOH fate is translocation to an acceptor membrane/lipoprotein, where one- or two-electron reduction may then ensue. In the case of cholesterol (Ch)-derived hydroperoxides (ChOOHs), translocation can be specifically stimulated by StAR family trafficking proteins, which are normally involved in Ch homeostasis and Ch-mediated steroidogenesis. In this review, we discuss how these processes can be impaired by StAR-mediated ChOOH and Ch co-trafficking to mitochondria of vascular macrophages and steroidogenic cells, respectively. The protective effects of endogenous selenoperoxidase, GPx4, are also discussed. This is the first known example of detrimental ChOOH transfer via a natural Ch trafficking pathway and inhibition thereof by GPx4.

Is lithium neuroprotective? An updated mechanistic illustrated review

Neurodegeneration is a pathological process characterized by progressive neuronal impairment, dysfunction, and loss due to mitochondrial dysfunction, oxidative stress, inflammation, and apoptosis. Many studies have shown that lithium protects against neurodegeneration. Herein, we summarize recent clinical and laboratory studies on the neuroprotective effects of lithium against neurodegeneration and its potential to modulate mitochondrial dysfunction, oxidative stress, inflammation, and apoptosis. Recent findings indicate that lithium regulates critical intracellular pathways such as phosphatidylinositol-3 (PI3)/protein kinase B (Akt)/glycogen synthase kinase-3 (GSK3β) and PI3/Akt/response element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF). We queried PubMed, Web of Science, Scopus, Elsevier, and other related databases using search terms related to lithium and its neuroprotective effect in various neurodegenerative diseases and events from January 2000 to May 2022. We reviewed the major findings and mechanisms proposed for the effects of lithium. Lithium's neuroprotective potential against neural cell degeneration is mediated by inducing anti-inflammatory factors, antioxidant enzymes, and free radical scavengers to prevent mitochondrial dysfunction. Lithium effects are regulated by two essential pathways: PI3/Akt/GSK3β and PI3/Akt/CREB/BDNF. Lithium acts as a neuroprotective agent against neurodegeneration by preventing inflammation, oxidative stress, apoptosis, and mitochondrial dysfunction using PI3/Akt/GSK3β and PI3/Akt/CREB/BDNF signaling pathways.

Directly imaging emergence of phase separation in peroxidized lipid membranes

Lipid peroxidation is a process which is key in cell signaling and disease, it is exploited in cancer therapy in the form of photodynamic therapy. The appearance of hydrophilic moieties within the bilayer's hydrocarbon core will dramatically alter the structure and mechanical behavior of membranes. Here, we combine viscosity sensitive fluorophores, advanced microscopy, and X-ray diffraction and molecular simulations to directly and quantitatively measure the bilayer's structural and viscoelastic properties, and correlate these with atomistic molecular modelling. Our results indicate an increase in microviscosity and a decrease in the bending rigidity upon peroxidation of the membranes, contrary to the trend observed with non-oxidized lipids. Fluorescence lifetime imaging microscopy and MD simulations give evidence for the presence of membrane regions of different local order in the oxidized membranes. We hypothesize that oxidation promotes stronger lipid-lipid interactions, which lead to an increase in the lateral heterogeneity within the bilayer and the creation of lipid clusters of higher order.

Synthesis, structural characterization and study of antioxidant and anti-PrPSc properties of flavonoids and their rhenium(I)-tricarbonyl complexes

This study aims at the synthesis and initial biological evaluation of novel rhenium-tricarbonyl complexes of 3,3',4',5,7-pentahydroxyflavone (quercetin), 3,7,4΄-trihydroxyflavone (resokaempferol), 5,7-dihydroxyflavone (chrysin) and 4΄,5,7-trihydroxyflavonone (naringenin) as neuroprotective and anti-PrP agents. Resokaempferol was synthesized from 2,2΄,4-trihydroxychalcone by H₂O₂/NaOH. The rhenium-tricarbonyl complexes of the type fac-[Re(CO)₃(Fl)(sol)] were synthesized by reacting the precursor fac-[Re(CO)₃(sol)₃]⁺ with an equimolar amount of the flavonoids (Fl) quercetin, resokaempferol, chrysin and naringenin and the solvent (sol) was methanol or water. The respective Re-flavonoid complexes were purified by semi-preparative HPLC and characterized by spectroscopic methods. Furthermore, the structure of Re-chrysin was elucidated by X-ray crystallography. Initial screening of the neuroprotective properties of these compounds included the in vitro assessment of the antioxidant properties by the DPPH assay as well as the anti-lipid peroxidation of linoleic acid in the presence of AAPH and their ability to inhibit soybean lipoxygenase. From the above studies, it was concluded that the complexes' properties are mainly correlated with the structural characteristics and the presence of the flavonoids. The flavonoids and their respective Re-complexes were also tested in vitro for their ability to inhibit the formation and aggregation of the amyloid-like abnormal prion protein, PrP^Sc, by employing the real-time quaking-induced conversion assay with recombinant PrP seeded with cerebrospinal fluid from patients with Creutzfeldt-Jakob disease. All the compounds blocked de novo abnormal PrP formation and aggregation.

Energy Crisis Links to Autophagy and Ferroptosis in Alzheimer's Disease: Current Evidence and Future Avenues

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases worldwide. The occult nature of the onset and the uncertainty of the etiology largely impede the development of therapeutic strategies for AD. Previous studies revealed that the disorder of energy metabolism in the brains of AD patients appears far earlier than the typical pathological features of AD, suggesting a tight association between energy crisis and the onset of AD. Energy crisis in the brain is known to be induced by the reductions in glucose uptake and utilization, which may be ascribed to the diminished expressions of cerebral glucose transporters (GLUTs), insulin resistance, mitochondrial dysfunctions, and lactate dysmetabolism. Notably, the energy sensors such as peroxisome proliferators-activated receptor (PPAR), transcription factor EB (TFEB), and AMP-activated protein kinase (AMPK) were shown to be the critical regulators of autophagy, which play important roles in regulating beta-amyloid (Aβ) metabolism, tau phosphorylation, neuroinflammation, iron dynamics, as well as ferroptosis. In this study, we summarized the current knowledge on the molecular mechanisms involved in the energy dysmetabolism of AD and discussed the interplays existing between energy crisis, autophagy, and ferroptosis. In addition, we highlighted the potential network in which autophagy may serve as a bridge between energy crisis and ferroptosis in the progression of AD. A deeper understanding of the relationship between energy dysmetabolism and AD may provide new insight into developing strategies for treating AD; meanwhile, the energy crisis in the progression of AD should gain more attention.

Vicious cycle of lipid peroxidation and iron accumulation in neurodegeneration

Lipid peroxidation and iron accumulation are closely associated with neurodegenerative diseases, such as Alzheimer's, Parkinson's, and Huntington's diseases, or neurodegeneration with brain iron accumulation disorders. Mitochondrial dysfunction, lipofuscin accumulation, autophagy disruption, and ferroptosis have been implicated as the critical pathomechanisms of lipid peroxidation and iron accumulation in these disorders. Currently, the connection between lipid peroxidation and iron accumulation and the initial cause or consequence in neurodegeneration processes is unclear. In this review, we have compiled the known mechanisms by which lipid peroxidation triggers iron accumulation and lipofuscin formation, and the effect of iron overload on lipid peroxidation and cellular function. The vicious cycle established between both pathological alterations may lead to the development of neurodegeneration. Therefore, the investigation of these mechanisms is essential for exploring therapeutic strategies to restrict neurodegeneration. In addition, we discuss the interplay between lipid peroxidation and iron accumulation in neurodegeneration, particularly in PLA2G6-associated neurodegeneration, a rare neurodegenerative disease with autosomal recessive inheritance, which belongs to the group of neurodegeneration with brain iron accumulation disorders.

Review of Current Human Genome-Scale Metabolic Models for Brain Cancer and Neurodegenerative Diseases

Brain disorders represent 32% of the global disease burden, with 169 million Europeans affected. Constraint-based metabolic modelling and other approaches have been applied to predict new treatments for these and other diseases. Many recent studies focused on enhancing, among others, drug predictions by generating generic metabolic models of brain cells and on the contextualisation of the genome-scale metabolic models with expression data. Experimental flux rates were primarily used to constrain or validate the model inputs. Bi-cellular models were reconstructed to study the interaction between different cell types. This review highlights the evolution of genome-scale models for neurodegenerative diseases and glioma. We discuss the advantages and drawbacks of each approach and propose improvements, such as building bi-cellular models, tailoring the biomass formulations for glioma and refinement of the cerebrospinal fluid composition.

Clinical implications of lipid peroxides levels in plasma and tumor tissue in breast cancer patients

Oxidative stress can promote the oxidation of lipoproteins and polyunsaturated fatty acids present in cell membranes; an event known as lipid peroxidation (LPO). LPO has been associated with carcinogenesis and cancer progression, however, its meaning concerning the clinicopathological aspects of human breast cancer is not clear. This study investigated LPO profiles in tumor and plasma samples from breast cancer patients (n = 140) considering their clinicopathological features (age at diagnosis, menopausal status, body mass index, tumor histological grade, tumor size, ki-67 proliferation index, presence of metastasis, chemotherapy response, the molecular subtype of cancer and overall survival status). LPO levels were estimated by tert-butyl hydroperoxide-initiated chemiluminescence. High LPO levels were found regarding poor prognosis parameters as young age at diagnosis (p = 0.006 in tissue), premenopausal patients (p = 0.012 in tissue), high-grade tumors (p = 0.010 in tissue and p = 0.002 in plasma), metastatic disease (p = 0.046 in tissue), chemoresistant tumors (p = 0.041 in tissue), disease relapse (p = 0.018 in tissue and p = 0.009 in plasma) and overall survival status (p = 0.001 in plasma). Our findings point out the clinical meaning of LPO and highlight it as an oxidative stress event linked to poor prognosis and disease aggressiveness in breast cancer patients.

Association of Oxidative Stress with Neurological Disorders

BACKGORUND

Oxidative stress is one of the main contributing factors involved in cerebral biochemical impairment. The higher susceptibility of the central nervous system to reactive oxygen species mediated damage could be attributed to several factors. For example, neurons use a greater quantity of oxygen, many parts of the brain have higher concentraton of iron, and neuronal mitochondria produce huge content of hydrogen peroxide. In addition, neuronal membranes have polyunsaturated fatty acids, which are predominantly vulnerable to oxidative stress (OS). OS is the imbalance between reactive oxygen species generation and cellular antioxidant potential. This may lead to various pathological conditions and diseases, especially neurodegenerative diseases such as, Parkinson's, Alzheimer's, and Huntington's diseases.

OBJECTIVES

In this study, we explored the involvement of OS in neurodegenerative diseases.

METHODS

We used different search terms like "oxidative stress and neurological disorders" "free radicals and neurodegenerative disorders" "oxidative stress, free radicals, and neurological disorders" and "association of oxidative stress with the name of disorders taken from the list of neurological disorders. We tried to summarize the source, biological effects, and physiologic functions of ROS.

RESULTS

Finally, it was noted that more than 190 neurological disorders are associated with oxidative stress.

CONCLUSION

More elaborated studies in the future will certainly help in understanding the exact mechanism involved in neurological diseases and provide insight into revelation of therapeutic targets.

The Selenoprotein Glutathione Peroxidase 4: From Molecular Mechanisms to Novel Therapeutic Opportunities

The selenoprotein glutathione peroxidase 4 (GPX4) is one of the main antioxidant mediators in the human body. Its central function involves the reduction of complex hydroperoxides into their respective alcohols often using reduced Glutathione (GSH) as a reducing agent. GPX4 has become a hotspot therapeutic target in biomedical research following its characterization as a chief regulator of ferroptosis, and its subsequent recognition as a specific pharmacological target for the treatment of an extensive variety of human diseases including cancers and neurodegenerative disorders. Several recent studies have provided insights into how GPX4 is distinguished from the rest of the glutathione peroxidase family, the unique biochemical properties of GPX4, how GPX4 is related to lipid peroxidation and ferroptosis, and how the enzyme may be modulated as a potential therapeutic target. This current report aims to review the literature underlying all these insights and present an up-to-date perspective on the current understanding of GPX4 as a potential therapeutic target.

Insamgobonhwan Protects Neuronal Cells from Lipid ROS and Improves Deficient Cognitive Function

Iron is an essential element in the central nervous system that is involved in many of its important biological processes, such as oxygen transportation, myelin production, and neurotransmitter synthesis. Previous studies have observed the selective accumulation of iron in Aβ aggregates and neurofibrillary tangles in the brains of patients with Alzheimer’s disease, and excess of this accumulation is associated with accelerated cognitive decline in Alzheimer’s patients. Emerging evidence suggests that ferroptosis, cell death due to iron accumulation, is a potential therapeutic target for treating Alzheimer’s disease. Insamgobonhwan (GBH) is a well-regarded traditional medicine from Donguibogam that possess antioxidant properties and has been suggested to slow the aging process. However, the neuroprotective role of GBH against lipid peroxidation-induced ferroptosis and its positive cognitive effects remain unexplored. Here, we investigated the ability of GBH to protect against RSL3-induced ferroptosis in vitro and to suppress amyloid-β-induced cognitive impairment in vivo. First, we treated HT22 cells with RSL3 to induce ferroptosis, which is an inhibitor of glutathione peroxidase 4 (GPX4) and induces lethal lipid hydroperoxide accumulation, reactive oxygen species (ROS) production, and ferroptotic cell death. GBH treatment inhibited cell death and lipid peroxidation, which were increased by RSL3 administration. In addition, GBH restored the expression of ferroptosis marker proteins, such as GPX4, HO-1 and COX-2, which were altered by RSL3. Next, we examined whether the protective ability of GBH in cells was reproduced in animals. We concluded that GBH treatment inhibited Aβ-induced lipid peroxidation and improved Aβ-induced cognitive impairment in mice.

Firefighters' occupational exposure: Contribution from biomarkers of effect to assess health risks

Firefighting is physically and physiologically exhausting besides encompassing exposure to toxic fire emissions. Biomonitoring studies from the past five years have been significantly contributing to characterize the occupational-related health effects in this group of professionals and to improve risk assessment. Therefore, this study gathers and critically discusses the most characterized biomarkers of effect (oxidative stress, DNA and protein damage, stress hormones, inflammation, and vascular, lung, and liver injury), including those potentially more promising to be explored in future studies, and their relation with health outcomes. Various studies proved an association between exposures to fire emissions and/or heat and significantly altered values of biomarkers of inflammation (soluble adhesion molecules, tumor necrosis factor, interleukins, and leucocyte count), vascular damage and tissue injury (pentraxin-3, vascular endothelial growth factor, and cardiac troponin T) in firefighting forces. Moreover, preliminary data of DNA damage in blood, urinary mutagenicity and 8-isoprostaglandin in exhaled breath condensate suggest that these biomarkers of oxidative stress should be further explored. However, most of the reported studies are based on cross-sectional designs, which limit full identification and characterization of the risk factors and their association with development of work-related diseases. Broader studies based on longitudinal designs and strongly supported by the analysis of several types of biomarkers in different biological fluids are further required to gain deeper insights into the firefighters occupational related health hazards and contribute to implementation of new or improved surveillance programs.

Activation of Antioxidant and Proteolytic Pathways in the Nigrostriatal Dopaminergic System After 3,4-Methylenedioxymethamphetamine Administration: Sex-Related Differences

3,4-Methylenedioxymethamphetamine (MDMA, “ecstasy”) is an amphetamine-related drug that may damage the dopaminergic nigrostriatal system. To investigate the mechanisms that sustain this toxic effect and ascertain their sex-dependence, we evaluated in the nigrostriatal system of MDMA-treated (4 × 20 mg/kg, 2 h apart) male and female mice the activity of superoxide dismutase (SOD), the gene expression of SOD type 1 and 2, together with SOD1/2 co-localization with tyrosine hydroxylase (TH)-positive neurons. In the same mice and brain areas, activity of glutathione peroxidase (GPx) and of β2/β5 subunits of the ubiquitin-proteasome system (UPS) were also evaluated. After MDMA, SOD1 increased in striatal TH-positive terminals, but not nigral neurons, of males and females, while SOD2 increased in striatal TH-positive terminals and nigral neurons of males only. Moreover, after MDMA, SOD1 gene expression increased in the midbrain of males and females, whereas SOD2 increased only in males. Finally, MDMA increased the SOD activity in the midbrain of females, without affecting GPx activity, decreased the β2/β5 activities in the striatum of males and the β2 activity in the midbrain of females. These results suggest that the mechanisms of MDMA-induced neurotoxic effects are sex-dependent and dopaminergic neurons of males could be more sensitive to SOD2- and UPS-mediated toxic effects.

Glutathione: An Old and Small Molecule with Great Functions and New Applications in the Brain and in Alzheimer's Disease

Significance: Glutathione (GSH) represents the most abundant and the main antioxidant in the body with important functions in the brain related to Alzheimer's disease (AD). Recent Advances: Oxidative stress is one of the central mechanisms in AD. We and others have demonstrated the alteration of GSH levels in the AD brain, its important role in the detoxification of advanced glycation end-products and of acrolein, a by-product of lipid peroxidation. Recent in vivo studies found a decrease of GSH in several areas of the brain from control, mild cognitive impairment, and AD subjects, which are correlated with cognitive decline. Critical Issues: Several strategies were developed to restore its intracellular level with the l-cysteine prodrugs or the oral administration of γ-glutamylcysteine to prevent alterations observed in AD. To date, no benefit on GSH level or on oxidative biomarkers has been reported in clinical trials. Thus, it remains uncertain if GSH could be considered a potential preventive or therapeutic approach or a biomarker for AD. Future Directions: We address how GSH-coupled nanocarriers represent a promising approach for the functionalization of nanocarriers to overcome the blood/brain barrier (BBB) for the brain delivery of GSH while avoiding cellular toxicity. It is also important to address the presence of GSH in exosomes for its potential intercellular transfer or its shuttle across the BBB under certain conditions. Antioxid. Redox Signal. 35, 270-292.

Cadmium promotes glycolysis upregulation and glutamine dependency in human neuronal cells

Cadmium is a widespread pollutant, which easily accumulates inside the human body with an estimated half-life of 25-30 years. Many data strongly suggest that it may play a role in the pathogenesis of neurodegenerative diseases. In this paper we investigated cadmium effect on human SH-SY5Y neuroblastoma cells metabolism. Results showed that, although SH-SY5Y cells already showed hyperactivated glycolysis, cadmium further increased basal glycolytic rate. Both glycolytic capacity and reserve were also increased following cadmium administration, endowing the cells with a higher compensatory glycolysis when oxidative phosphorylation was inhibited. Cadmium administration also led to an increase in glycolytic ATP production rate, paralleled by a decrease in ATP production by oxidative phosphorylation, due to an impairment of mitochondrial respiration. Moreover, following cadmium administration, mitochondria increased their dependency on glutamine, while decreasing lipids oxidation. On the whole, our data show that cadmium exacerbates the Warburg effect and promotes the use of glutamine as a substrate for lipid biosynthesis. Although increased glutamine consumption leads to an increase in glutathione level, this cannot efficiently counteract cadmium-induced oxidative stress, leading to membrane lipid peroxidation. Oxidative stress represents a serious threat for neuronal cells and our data confirm glutathione as a key defense mechanism.

Pharmacological evaluation of vanillic acid in rotenone-induced Parkinson's disease rat model

In the present study, we investigated the anti-Parkinson's effect of vanillic acid (VA) (12 mg/kg, 25 mg/kg, 50 mg/kg p.o.) against rotenone (2 mg/kg s.c.) induced Parkinson's disease (PD) in rats. The continuous administration of rotenone for 35 days resulted in rigidity in muscles, catalepsy, and decrease in locomotor activity, body weight, and rearing behaviour along with the generation of oxidative stress in the brain (rise in the TBARS, and SAG level and reduced CAT, and GSH levels). Co-treatment of VA and levodopa-carbidopa (100 mg/kg + 25 mg/kg p.o.) lead to a significant (P < 0.001) reduction in the muscle rigidity and catalepsy along with a significant (P < 0.001) increase in body weight, rearing behaviour, locomotion and muscle activity as compared to the rotenone-treated group in the dose dependent manner, showing maximum effect at the 50 mg/kg. It also showed reversal of levels of oxidative stress parameters thus, reducing the neuronal oxidative stress. The level of DA was also estimated which showed an increase in the level of DA in the VA plus standard drug treated animals as compared to rotenone treated group. Histopathological evaluation showed a high number of eosinophilic lesions in the rotenone group which were found to be very less in the VA co-treated group. The study thus proved that co-treatment of VA and levodopa-carbidopa, significantly protected the brain from neuronal damage due to oxidative stress and attenuated the motor defects indicating the possible therapeutic potential of VA as a neuroprotective in PD.

Lipid Peroxidation Assessment in Preclinical Alzheimer Disease Diagnosis

BACKGROUND

Alzheimer disease (AD) is an increasingly common neurodegenerative disease, especially in countries with aging populations. Its diagnosis is complex and is usually carried out in advanced stages of the disease. In addition, lipids and oxidative stress have been related to AD since the earliest stages. A diagnosis in the initial or preclinical stages of the disease could help in a more effective action of the treatments.

METHODS

Isoprostanoid biomarkers were determined in plasma samples from preclinical AD participants (n = 12) and healthy controls (n = 31) by chromatography and mass spectrometry (UPLC-MS/MS). Participants were accurately classified according to cerebrospinal fluid (CSF) biomarkers and neuropsychological examination.

RESULTS

Isoprostanoid levels did not show differences between groups. However, some of them correlated with CSF biomarkers (t-tau, p-tau) and with cognitive decline. In addition, a panel including 10 biomarkers showed an area under curve (AUC) of 0.96 (0.903-1) and a validation AUC of 0.90 in preclinical AD prediction.

CONCLUSIONS

Plasma isoprostanoids could be useful biomarkers in preclinical diagnosis for AD. However, these results would require a further validation with an external cohort.

Ferroptosis: A potential therapeutic target for neurodegenerative diseases

Ferroptosis is a newly identified regulated form of cell death, which is thought to play a major role in neurodegenerative diseases. In this review, we discuss recent studies elucidating the molecular mechanisms involved in the regulation and execution of ferroptotic cell death and also its role in the brain. Ferroptosis is regulated mainly via iron homeostasis, glutathione metabolism, and lipid peroxidation. Ferroptotic cell death and pro-ferroptotic factors are correlated with the etiopathogenesis of Parkinson's disease (PD) and Alzheimer's disease (AD). Ferroptosis and etiological factors act synergistically in PD and AD pathogenesis. Furthermore, several preclinical and clinical studies targeting ferroptosis in PD and AD have also shown positive results. Evidence of ferroptosis in the brain thus gives new insights into understanding neurodegenerative diseases. Ferroptosis studies in the brain are still in their infancy, but the existing pieces of evidence suggest a strong correlation between ferroptotic cell death and neurodegenerative diseases. Thus, ferroptosis might be a promising target for treating neurodegenerative diseases.

The Chemistry and Biology of Ferroptosis

Ferroptosis is a recently described form of cell death driven by iron-dependent lipid peroxidation. This type of cell death was first observed in response to treatment of tumor cells with a small-molecule chemical probe named erastin. Most subsequent advances in understanding the mechanisms governing ferroptosis involved the use of genetic screens and small-molecule probes. We describe herein the utility and limitations of chemical probes that have been used to analyze and perturb ferroptosis, as well as mechanistic studies of ferroptosis that benefitted from the use of these probes and genetic screens. We also suggest probes for ferroptosis and highlight mechanistic questions surrounding this form of cell death that will be a high priority for exploration in the future.

WDR45 Mutation Impairs the Autophagic Degradation of Transferrin Receptor and Promotes Ferroptosis

WDR45 is an autophagy-related protein that involves in the formation of autophagosome. Mutations in WDR45 lead to the impairment of autophagy which is associated with the human β-propeller protein-associated neurodegeneration (BPAN). However, the relationship between autophagy and brain iron accumulation in patients with BPAN remains unclear. Here, we demonstrated that transferrin receptor (TfRC) which is critical for the iron import of cells was degraded via autophagy. TfRC was accumulated after the inhibition of autophagy by treatment with autophagic inhibitor chloroquine or knockdown of ATG2A. The intracellular iron content was increased in cells overexpressing TfRC or mutant WDR45, however, ferritin H (FTH) chain was decreased. Increased TfRC and simultaneously decreased FTH consequently resulted in an elevated level of ferrous iron (Fe²⁺) which further promoted cell ferroptosis, demonstrated by the increased lipid peroxidation and reactive oxygen species (ROS) and the decreased glutathione peroxidase 4 (GPX4) and cell viability. Taken together, these findings provide a piece of important evidence that WDR45 deficiency impairs autophagic degradation of TfRC, therefore leading to iron accumulation, and the elevated iron promotes ferroptosis which may contribute to the progression of BPAN.

Effect of Quercetin on ABCC6 Transporter: Implication in HepG2 Migration

Quercetin is a member of the flavonoid group of compounds, which is abundantly present in various dietary sources. It has excellent antioxidant properties and anti-inflammatory activity and is very effective as an anti-cancer agent against various types of tumors, both in vivo and in vitro. Quercetin has been also reported to modulate the activity of some members of the multidrug-resistance transporters family, such as P-gp, ABCC1, ABCC2, and ABCG2, and the activity of ecto-5′-nucleotidase (NT5E/CD73), a key regulator in some tumor processes such as invasion, migration, and metastasis. In this study, we investigated the effect of Quercetin on ABCC6 expression in HepG2 cells. ABCC6 is a member of the superfamily of ATP-binding cassette (ABC) transporters, poorly involved in drug resistance, whose mutations cause pseudoxanthoma elasticum, an inherited disease characterized by ectopic calcification of soft connective tissues. Recently, it has been reported that ABCC6 contributes to cytoskeleton rearrangements and HepG2 cell motility through purinergic signaling. Gene and protein expression were evaluated by quantitative Reverse-Transcription PCR (RT-qPCR) and western blot, respectively. Actin cytoskeleton dynamics was evaluated by laser confocal microscopy using fluorophore-conjugated phalloidin. Cell motility was analyzed by an in vitro wound-healing migration assay. We propose that ABCC6 expression may be controlled by the AKT pathway as part of an adaptative response to oxidative stress, which can be mitigated by the use of Quercetin-like flavonoids.

Circulating Tumour Cells as Prognostic Biomarkers in Colorectal Cancer: A Systematic Review

Despite therapeutic advances, colorectal cancer (CRC) is still one of the deadliest cancers, partly due to local recurrence and metastatic disease. Tumour cells that spread by gaining access to peripheral blood are called circulating tumour cells (CTCs). These may be present before there are any clinical signs, but can be detected within blood samples. CTCs from patients with CRC may be isolated in a laboratory for characterization and multiple analyses. In this review, we focus on the prognostic potential of CTCs detection, by evaluating the reported progress and applications of such analyses. Our search found 77 relevant studies that reported CTC detection in CRC. Both cell count and features were reported as promising prognosis biomarkers. Since CTCs are rare and can lose their differentiation, new tools are being developed to improve detection. CTCs may have potential as prognostic biomarkers for CRC in terms of survival prediction, anticipating chemotherapy resistance, and surgical planning. CTCs are not yet used in clinical practice, and further investigations are required in order to better frame their practical value.

Ferroptosis contributes to isoflurane-induced neurotoxicity and learning and memory impairment

Ferroptosis is a novel type of programmed cell death, which is different from apoptosis and autophagic cell death. Recently, ferroptosis has been indicated to contribute to the in vitro neurotoxicity induced by isoflurane, which is one of the most common anesthetics in clinic. However, the in vivo position of ferroptosis in isoflurane-induced neurotoxicity as well as learning and memory impairment remains unclear. In this study, we mainly explored the relationship between ferroptosis and isoflurane-induced learning and memory, as well as the therapeutic methods in mouse model. Our results indicated that isoflurane induced the ferroptosis in a dose-dependent and time-dependent manner in hippocampus, the organ related with learning and memory ability. In addition, the activity of cytochrome c oxidase/Complex IV in mitochondrial electron transport chain (ETC) was increased by isoflurane, which might further contributed to cysteine deprivation-induced ferroptosis caused by isoflurane exposure. More importantly, isoflurane-induced ferroptosis could be rescued by both ferroptosis inhibitor (ferrostatin-1) and mitochondria activator (dimethyl fumarate), which also showed effective therapeutic action against isoflurane-induced learning and memory impairment. Taken together, our data indicate the close association among ferroptosis, mitochondria and isoflurane, and provide a novel insight into the therapy mode against isoflurane-induced learning and memory impairment.

Effect of Quercetin on ABCC6 Transporter: Implication in HepG2 Migration

Quercetin is a member of the flavonoid group of compounds, which is abundantly present in various dietary sources. It has excellent antioxidant properties and anti-inflammatory activity and is very effective as an anti-cancer agent against various types of tumors, both in vivo and in vitro. Quercetin has been also reported to modulate the activity of some members of the multidrug-resistance transporters family, such as P-gp, ABCC1, ABCC2, and ABCG2, and the activity of ecto-5′-nucleotidase (NT5E/CD73), a key regulator in some tumor processes such as invasion, migration, and metastasis. In this study, we investigated the effect of Quercetin on ABCC6 expression in HepG2 cells. ABCC6 is a member of the superfamily of ATP-binding cassette (ABC) transporters, poorly involved in drug resistance, whose mutations cause pseudoxanthoma elasticum, an inherited disease characterized by ectopic calcification of soft connective tissues. Recently, it has been reported that ABCC6 contributes to cytoskeleton rearrangements and HepG2 cell motility through purinergic signaling. Gene and protein expression were evaluated by quantitative Reverse-Transcription PCR (RT-qPCR) and western blot, respectively. Actin cytoskeleton dynamics was evaluated by laser confocal microscopy using fluorophore-conjugated phalloidin. Cell motility was analyzed by an in vitro wound-healing migration assay. We propose that ABCC6 expression may be controlled by the AKT pathway as part of an adaptative response to oxidative stress, which can be mitigated by the use of Quercetin-like flavonoids.

The Neuromelanin Paradox and Its Dual Role in Oxidative Stress and Neurodegeneration

Aging is associated with an increasing dysfunction of key brain homeostasis mechanisms and represents the main risk factor across most neurodegenerative disorders. However, the degree of dysregulation and the affectation of specific pathways set apart normal aging from neurodegenerative disorders. In particular, the neuronal metabolism of catecholaminergic neurotransmitters appears to be a specifically sensitive pathway that is affected in different neurodegenerations. In humans, catecholaminergic neurons are characterized by an age-related accumulation of neuromelanin (NM), rendering the soma of the neurons black. This intracellular NM appears to serve as a very efficient quencher for toxic molecules. However, when a neuron degenerates, NM is released together with its load (many undegraded cellular components, transition metals, lipids, xenobiotics) contributing to initiate and worsen an eventual immune response, exacerbating the oxidative stress, ultimately leading to the neurodegenerative process. This review focuses on the analysis of the role of NM in normal aging and neurodegeneration related to its capabilities as an antioxidant and scavenging of harmful molecules, versus its involvement in oxidative stress and aberrant immune response, depending on NM saturation state and its extracellular release.

Sulfiredoxin-1 protects spinal cord neurons against oxidative stress in the oxygen-glucose deprivation/reoxygenation model through the bax/cytochrome c/caspase 3 apoptosis pathway

BACKGROUND

Spinal cord ischemia/reperfusion injury is a common clinical, pathophysiological phenomenon with complex molecular mechanisms. Currently, there are no therapeutics available to alleviate the same. This study investigates the protective effects of sulfiredoxin-1 (Srxn 1) on spinal cord neurons following exposure to oxygen-glucose deprivation/reoxygenation (OGD/R) treatment.

MATERIALS AND METHODS

Primary spinal cord neurons were cultured, detected by anti-tubulin βⅢ, and transfected with adeno-associated virus (AAV)-Srxn 1 to overexpress Srxn 1. They were identified by their morphology and CCK-8 assay. The superoxide dismutase level was measured by superoxide dismutase assay. Malondialdehyde level was measured by malondialdehyde assay. The apoptosis ratio was calculated by Hoechst 33342 and Annexin V-PE/7-AAD staining. Mitochondrial transmembrane potential (Δψm) was detected by tetramethylrhodamine-methyl ester-perchlorate (TMRM) staining. The mRNA expression levels of Srxn 1 and caspase 3 were detected by quantitative reverse transcription-polymerase chain reaction, and the protein expression levels of Srxn 1, bax, bcl-2, cytosolic cytochrome c, and caspase 3 were detected by western blotting.

RESULTS

AAV-Srxn 1 up-regulated mRNA and protein levels of Srxn 1 in spinal cord neurons. Following exposure to OGD/R, overexpression of Srxn 1 improved the neuronal viability, alleviated the neuron apoptosis, enhanced the mitochondrial transmembrane potential, increased the SOD level, decreased the MDA level, inhibited the expression of cytosolic cytochrome c, bax, and caspase 3, and promoted the expression of bcl-2.

CONCLUSION

Srxn 1 plays a significant role in anti-apoptosis of spinal cord neurons, and Srxn 1 may be a potential therapeutic target for spinal cord I/R injury.

Determination of Cytokines and Oxidative Stress Biomarkers in Cognitive Impairment Induced by Methylmalonic Acidemia

OBJECTIVE

Methylmalonic acidemia (MMA) is the most common organic acidemia in children. Many patients with MMA suffered from cognitive impairments. The aim of this study was to identify the significance of cytokines and oxidative stress biomarkers in MMA-induced cognitive impairment.

METHODS

We enrolled 64 children with combined MMA and homocystinuria and 64 age- and sex-matched healthy volunteers. Participants were subsequently classified as with or without cognitive impairments using a uniform neuropsychological assessment test. Serum samples were collected. The serum levels of cytokines and oxidative stress biomarkers were measured using the ELISA or chemical methods.

RESULTS

Compared to control group, the serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, malondialdehyde (MDA), and nitric oxide (NO) in the MMA patients increased markedly (p < 0.05); glutathione (GSH) and superoxide dismutase (SOD) decreased obviously (p < 0.01). The levels of IL-6, TNF-α, NO, and MDA in the serum were negatively associated with DQ or IQ scores. The levels of GSH and SOD in the serum were positively correlated with DQ or IQ scores. After receiver operating characteristic curve analysis, NO was the most useful individual marker for distinguishing the cognitive dysfunction, corresponding to the area under ROC curve (AUC) of 0.82 (95% CI, 0.74-0.91), sensitivity of 76.60%, and specificity of 80.25%. GSH and MDA were also useful for diagnosis of MMA-induced cognitive dysfunction, corresponding to the AUC of 0.80 (95% CI, 0.70-0.89), and 0.73 (95% CI, 0.63-0.82), respectively. The sensitivity and specificity of GSH were 72.34 and 80.25%, respectively. The sensitivity and specificity of MDA were 85.11 and 51.85%, respectively.

CONCLUSIONS

The high-concentration methylmalonic acid in the blood induced immune cells to release pro-inflammatory cytokines such as TNF-α and IL-6. These cytokines and high-concentration methylmalonic acid stimulated the immune cells to produce reactive oxygen species (ROS) and reactive nitrogen species (RNS). The serum methylmalonic acid, cytokines, ROS, and RNS were across the blood-brain barrier and induced cognitive impairment. The small molecule substances such as serum NO, MDA, and GSH participated in the process of neuroinflammation and oxidative stress injury induced by MMA and could be useful for distinguishing the cognitive impairment.

An Overview of Structural Aspects and Health Beneficial Effects of Antioxidant Oligosaccharides

BACKGROUND

Non-digestible oligosaccharides are versatile sources of chemical diversity, well known for their prebiotic actions, found naturally in plants or produced by chemical or enzymatic synthesis or by hydrolysis of polysaccharides. Compared to polyphenols or even polysaccharides, the antioxidant potential of oligosaccharides is still unexplored. The aim of the present work was to provide an up-to-date, broad and critical contribution on the topic of antioxidant oligosaccharides.

METHODS

The search was performed by crossing the words oligosaccharides and antioxidant. Whenever possible, attempts at establishing correlations between chemical structure and antioxidant activity were undertaken.

RESULTS

The most representative in vitro and in vivo studies were compiled in two tables. Chitooligosaccharides and xylooligosaccharides and their derivatives were the most studied up to now. The antioxidant activities of oligosaccharides depend on the degree of polymerization and the method used for depolymerization. Other factors influencing the antioxidant strength are solubility, monosaccharide composition, the type of glycosidic linkages of the side chains, molecular weight, reducing sugar content, the presence of phenolic groups such as ferulic acid, and the presence of uronic acid, among others. Modification of the antioxidant capacity of oligosaccharides has been achieved by adding diverse organic groups to their structures, thus increasing also the spectrum of potentially useful molecules.

CONCLUSION

A great amount of high-quality evidence has been accumulating during the last decade in support of a meaningful antioxidant activity of oligosaccharides and derivatives. Ingestion of antioxidant oligosaccharides can be visualized as beneficial to human and animal health.

Iron Serum Markers Profile in Frontotemporal Lobar Degeneration

Frontotemporal lobar degeneration (FTLD) is a progressive neurodegenerative syndrome. Defects of copper (Cu) and iron (Fe) homeostasis are involved in the development of several neurodegenerative diseases and their homeostasis is interconnected by the Cu-protein ceruloplasmin (Cp), responsible for Fe oxidative state. In this study we assessed Fe, transferrin (Trf), ferritin, Cp specific activity (eCp/iCp), Cp/Trf ratio, and Trf saturation in 60 FTLD patients and 43 healthy controls, and discussed the results in relation to Cu homeostasis. The significant decrease of the eCp/iCp in the FTLD patients supports the involvement of Fe imbalance in the onset and progression of FTLD.

Oxidative stress and diabetic retinopathy: Molecular mechanisms, pathogenetic role and therapeutic implications

Oxidative stress, a cytopathic outcome of excessive generation of ROS and the repression of antioxidant defense system for ROS elimination, is involved in the pathogenesis of multiple diseases, including diabetes and its complications. Retinopathy, a microvascular complication of diabetes, is the primary cause of acquired blindness in diabetic patients. Oxidative stress has been verified as one critical contributor to the pathogenesis of diabetic retinopathy. Oxidative stress can both contribute to and result from the metabolic abnormalities induced by hyperglycemia, mainly including the increased flux of the polyol pathway and hexosamine pathway, the hyper-activation of protein kinase C (PKC) isoforms, and the accumulation of advanced glycation end products (AGEs). Moreover, the repression of the antioxidant defense system by hyperglycemia-mediated epigenetic modification also leads to the imbalance between the scavenging and production of ROS. Excessive accumulation of ROS induces mitochondrial damage, cellular apoptosis, inflammation, lipid peroxidation, and structural and functional alterations in retina. Therefore, it is important to understand and elucidate the oxidative stress-related mechanisms underlying the progress of diabetic retinopathy. In addition, the abnormalities correlated with oxidative stress provide multiple potential therapeutic targets to develop safe and effective treatments for diabetic retinopathy. Here, we also summarized the main antioxidant therapeutic strategies to control this disease.

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Oxidative stress can both contribute to and result from hyperglycemia-induced metabolic abnormalities in retina.

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Genes important in regulation of ROS are epigenetically modified, increasing ROS accumulation in retina.

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Oxidative stress is closely associated with the pathological changes in the progress of diabetic retinopathy.

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Antioxidants ameliorate retinopathy through targeting multiple steps of oxidative stress.

Non-Coding RNAs as Sensors of Oxidative Stress in Neurodegenerative Diseases

Oxidative stress (OS) results from an imbalance between the production of reactive oxygen species and the cellular antioxidant capacity. OS plays a central role in neurodegenerative diseases, where the progressive accumulation of reactive oxygen species induces mitochondrial dysfunction, protein aggregation and inflammation. Regulatory non-protein-coding RNAs (ncRNAs) are essential transcriptional and post-transcriptional gene expression controllers, showing a highly regulated expression in space (cell types), time (developmental and ageing processes) and response to specific stimuli. These dynamic changes shape signaling pathways that are critical for the developmental processes of the nervous system and brain cell homeostasis. Diverse classes of ncRNAs have been involved in the cell response to OS and have been targeted in therapeutic designs. The perturbed expression of ncRNAs has been shown in human neurodegenerative diseases, with these changes contributing to pathogenic mechanisms, including OS and associated toxicity. In the present review, we summarize existing literature linking OS, neurodegeneration and ncRNA function. We provide evidences for the central role of OS in age-related neurodegenerative conditions, recapitulating the main types of regulatory ncRNAs with roles in the normal function of the nervous system and summarizing up-to-date information on ncRNA deregulation with a direct impact on OS associated with major neurodegenerative conditions.

The Nrf2 induction prevents ferroptosis in Friedreich's Ataxia

Ferroptosis is an iron-dependent cell death caused by impaired glutathione metabolism, lipid peroxidation and mitochondrial failure. Emerging evidences report a role for ferroptosis in Friedreich's Ataxia (FRDA), a neurodegenerative disease caused by the decreased expression of the mitochondrial protein frataxin. Nrf2 signalling is implicated in many molecular aspects of ferroptosis, by upstream regulating glutathione homeostasis, mitochondrial function and lipid metabolism. As Nrf2 is down-regulated in FRDA, targeting Nrf2-mediated ferroptosis in FRDA may be an attractive option to counteract neurodegeneration in such disease, thus paving the way to new therapeutic opportunities. In this study, we evaluated ferroptosis hallmarks in frataxin-silenced mouse myoblasts, in hearts of a frataxin Knockin/Knockout (KIKO) mouse model, in skin fibroblasts and blood of patients, particularly focusing on ferroptosis-driven gene expression, mitochondrial impairment and lipid peroxidation. The efficacy of Nrf2 inducers to neutralize ferroptosis has been also evaluated.