The redox language in neurodegenerative diseases: oxidative post-translational modifications by hydrogen peroxide

Oxidative stress modulating nanomaterials and their biochemical roles in nanomedicine

Many pathological conditions are predominantly associated with oxidative stress, arising from reactive oxygen species (ROS); therefore, the modulation of redox activities has been a key strategy to restore normal tissue functions. Current approaches involve establishing a favorable cellular redox environment through the administration of therapeutic drugs and redox-active nanomaterials (RANs). In particular, RANs not only provide a stable and reliable means of therapeutic delivery but also possess the capacity to finely tune various interconnected components, including radicals, enzymes, proteins, transcription factors, and metabolites. Here, we discuss the roles that engineered RANs play in a spectrum of pathological conditions, such as cancer, neurodegenerative diseases, infections, and inflammation. We visualize the dual functions of RANs as both generator and scavenger of ROS, emphasizing their profound impact on diverse cellular functions. The focus of this review is solely on inorganic redox-active nanomaterials (inorganic RANs). Additionally, we deliberate on the challenges associated with current RANs-based approaches and propose potential research directions for their future clinical translation.

Mitochondrial dysfunction in sepsis: mechanisms and therapeutic perspectives

Sepsis is a severe medical condition characterized by a systemic inflammatory response, often culminating in multiple organ dysfunction and high mortality rates. In recent years, there has been a growing recognition of the pivotal role played by mitochondrial damage in driving the progression of sepsis. Various factors contribute to mitochondrial impairment during sepsis, encompassing mechanisms such as reactive nitrogen/oxygen species generation, mitophagy inhibition, mitochondrial dynamics change, and mitochondrial membrane permeabilization. Damaged mitochondria actively participate in shaping the inflammatory milieu by triggering key signaling pathways, including those mediated by Toll-like receptors, NOD-like receptors, and cyclic GMP-AMP synthase. Consequently, there has been a surge of interest in developing therapeutic strategies targeting mitochondria to mitigate septic pathogenesis. This review aims to delve into the intricate mechanisms underpinning mitochondrial dysfunction during sepsis and its significant impact on immune dysregulation. Moreover, we spotlight promising mitochondria-targeted interventions that have demonstrated therapeutic efficacy in preclinical sepsis models.

Phloroglucinol Derivatives Exert Anti-Inflammatory Effects and Attenuate Cognitive Impairment in LPS-Induced Mouse Model

Neuroinflammation is an inflammatory immune response that arises in the central nervous system. It is one of the primary causes of neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease. Phloroglucinol (PG) is a natural product contained in extracts of plant, algae and microbe and has been reported to have antioxidant and anti-inflammatory properties. In this study, we synthesized PG derivatives to enhance antioxidant and anti-inflammatory activity. Among PG derivatives, 6 a suppressed pro-oxidative and inflammatory molecule nitric oxide (NO) production more effectively than PG. Moreover, 6 a dose-dependently reduced the expression of proinflammatory cytokines such as IL-6, IL-1β, TNF-α, and NO producing enzyme iNOS in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. Additionally, we confirmed that 6 a alleviated cognitive impairment and glial activation in mouse model of LPS-induced neuroinflammation. These findings suggest that novel PG derivative, 6 a, is a potential treatment for neurodegenerative diseases.

Oxidative stress and aging: synergies for age related diseases

Aging is characterized by a progressive decline in physiological function and underlies several disabilities, including the increased sensitivity of cells and tissues to undergo pathological oxidative stress. In recent years, efforts have been made to better understand the relationship between age and oxidative stress and further develop therapeutic strategies to minimize the impact of both events on age-related diseases. In this work, we review the impact of the oxidant and antioxidant systems during aging and disease development and discuss the crosstalk of oxidative stress and other aging processes, with a focus on studies conducted in elderly populations.

Potential application of aptamers combined with DNA nanoflowers in neurodegenerative diseases

The efficacy of neurotherapeutic drugs hinges on their ability to traverse the blood-brain barrier and access the brain, which is crucial for treating or alleviating neurodegenerative diseases (NDs). Given the absence of definitive cures for NDs, early diagnosis and intervention become paramount in impeding disease progression. However, conventional therapeutic drugs and existing diagnostic approaches must meet clinical demands. Consequently, there is a pressing need to advance drug delivery systems and early diagnostic methods tailored for NDs. Certain aptamers endowed with specific functionalities find widespread utility in the targeted therapy and diagnosis of NDs. DNA nanoflowers (DNFs), distinctive flower-shaped DNA nanomaterials, are intricately self-assembled through rolling ring amplification (RCA) of circular DNA templates. Notably, imbuing DNFs with diverse functionalities becomes seamlessly achievable by integrating aptamer sequences with specific functions into RCA templates, resulting in a novel nanomaterial, aptamer-bound DNFs (ADNFs) that amalgamates the advantageous features of both components. This article delves into the characteristics and applications of aptamers and DNFs, exploring the potential or application of ADNFs in drug-targeted delivery, direct treatment, early diagnosis, etc. The objective is to offer prospective ideas for the clinical treatment or diagnosis of NDs, thereby contributing to the ongoing efforts in this critical field.

NADPH oxidase 4 (NOX4) as a biomarker and therapeutic target in neurodegenerative diseases

Diseases like Alzheimer's and Parkinson's diseases are defined by inflammation and the damage neurons undergo due to oxidative stress. A primary reactive oxygen species contributor in the central nervous system, NADPH oxidase 4, is viewed as a potential therapeutic touchstone and indicative marker for these ailments. This in-depth review brings to light distinct features of NADPH oxidase 4, responsible for generating superoxide and hydrogen peroxide, emphasizing its pivotal role in activating glial cells, inciting inflammation, and disturbing neuronal functions. Significantly, malfunctioning astrocytes, forming the majority in the central nervous system, play a part in advancing neurodegenerative diseases, due to their reactive oxygen species and inflammatory factor secretion. Our study reveals that aiming at NADPH oxidase 4 within astrocytes could be a viable treatment pathway to reduce oxidative damage and halt neurodegenerative processes. Adjusting NADPH oxidase 4 activity might influence the neuroinflammatory cytokine levels, including myeloperoxidase and osteopontin, offering better prospects for conditions like Alzheimer's disease and Parkinson's disease. This review sheds light on the role of NADPH oxidase 4 in neural degeneration, emphasizing its drug target potential, and paving the path for novel treatment approaches to combat these severe conditions.

Redox Homeostasis, Gut Microbiota, and Epigenetics in Neurodegenerative Diseases: A Systematic Review

Neurodegenerative diseases encompass a spectrum of disorders marked by the progressive degeneration of the structure and function of the nervous system. These conditions, including Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's disease (HD), Amyotrophic lateral sclerosis (ALS), and Multiple sclerosis (MS), often lead to severe cognitive and motor deficits. A critical component of neurodegenerative disease pathologies is the imbalance between pro-oxidant and antioxidant mechanisms, culminating in oxidative stress. The brain's high oxygen consumption and lipid-rich environment make it particularly vulnerable to oxidative damage. Pro-oxidants such as reactive nitrogen species (RNS) and reactive oxygen species (ROS) are continuously generated during normal metabolism, counteracted by enzymatic and non-enzymatic antioxidant defenses. In neurodegenerative diseases, this balance is disrupted, leading to neuronal damage. This systematic review explores the roles of oxidative stress, gut microbiota, and epigenetic modifications in neurodegenerative diseases, aiming to elucidate the interplay between these factors and identify potential therapeutic strategies. We conducted a comprehensive search of articles published in 2024 across major databases, focusing on studies examining the relationships between redox homeostasis, gut microbiota, and epigenetic changes in neurodegeneration. A total of 161 studies were included, comprising clinical trials, observational studies, and experimental research. Our findings reveal that oxidative stress plays a central role in the pathogenesis of neurodegenerative diseases, with gut microbiota composition and epigenetic modifications significantly influencing redox balance. Specific bacterial taxa and epigenetic markers were identified as potential modulators of oxidative stress, suggesting novel avenues for therapeutic intervention. Moreover, recent evidence from human and animal studies supports the emerging concept of targeting redox homeostasis through microbiota and epigenetic therapies. Future research should focus on validating these targets in clinical settings and exploring the potential for personalized medicine strategies based on individual microbiota and epigenetic profiles.

Balanced Duality: H2O2-Based Therapy in Cancer and Its Protective Effects on Non-Malignant Tissues

Conventional cancer therapy strategies, although centered around killing tumor cells, often lead to severe side effects on surrounding normal tissues, thus compromising the chronic quality of life in cancer survivors. Hydrogen peroxide (H2O2) is a secondary signaling molecule that has an array of functions in both tumor and normal cells, including the promotion of cell survival pathways and immune cell modulation in the tumor microenvironment. H2O2 is a reactive oxygen species (ROS) crucial in cellular homeostasis and signaling (at concentrations maintained under nM levels), with increased steady-state levels in tumors relative to their normal tissue counterparts. Increased steady-state levels of H2O2 in tumor cells, make them vulnerable to oxidative stress and ultimately, cell death. Recently, H2O2-producing therapies-namely, pharmacological ascorbate and superoxide dismutase mimetics-have emerged as compelling complementary treatment strategies in cancer. Both pharmacological ascorbate and superoxide dismutase mimetics can generate excess H2O2 to overwhelm the impaired H2O2 removal capacity of cancer cells. This review presents an overview of H2O2 metabolism in the physiological and malignant states, in addition to discussing the anti-tumor and normal tissue-sparing mechanism(s) of, and clinical evidence for, two H2O2-based therapies, pharmacological ascorbate and superoxide dismutase mimetics.

Advances and Challenges in Immune-Modulatory Biomaterials for Wound Healing Applications

Wound healing progresses through three distinct stages: inflammation, proliferation, and remodeling. Immune regulation is a central component throughout, crucial for orchestrating inflammatory responses, facilitating tissue repair, and restraining scar tissue formation. Elements such as mitochondria, reactive oxygen species (ROS), macrophages, autophagy, ferroptosis, and cytokines collaboratively shape immune regulation in this healing process. Skin wound dressings, recognized for their ability to augment biomaterials' immunomodulatory characteristics via antimicrobial, antioxidative, pro- or anti-inflammatory, and tissue-regenerative capacities, have garnered heightened attention. Notwithstanding, a lack of comprehensive research addressing how these dressings attain immunomodulatory properties and the mechanisms thereof persists. Hence, this paper pioneers a systematic review of biomaterials, emphasizing immune regulation and their underlying immunological mechanisms. It begins by highlighting the importance of immune regulation in wound healing and the peculiarities and obstacles faced in skin injury recovery. This segment explores the impact of wound metabolism, infections, systemic illnesses, and local immobilization on the immune response during healing. Subsequently, the review examines a spectrum of biomaterials utilized in skin wound therapy, including hydrogels, aerogels, electrospun nanofiber membranes, collagen scaffolds, microneedles, sponges, and 3D-printed constructs. It elaborates on the immunomodulatory approaches employed by these materials, focusing on mitochondrial and ROS modulation, autophagic processes, ferroptosis, macrophage modulation, and the influence of cytokines on wound healing. Acknowledging the challenge of antibiotic resistance, the paper also summarizes promising plant-based alternatives for biomaterial integration, including curcumin. In its concluding sections, the review charts recent advancements and prospects in biomaterials that accelerate skin wound healing via immune modulation. This includes exploring mitochondrial transplantation materials, biomaterial morphology optimization, metal ion incorporation, electrostimulation-enabled immune response control, and the benefits of composite materials in immune-regulatory wound dressings. The ultimate objective is to establish a theoretical foundation and guide future investigations in the realm of skin wound healing and related materials science disciplines.

Antioxidant and Neuroprotective Effects of Seed Oils from Trichosanthes kirilowii and T. laceribractea in Caenorhabditis elegans: A Comparative Analysis and Mechanism Study

Excess reactive oxygen species (ROS) can accelerate amyloid β (Aβ) aggregation and tau protein hyperphosphorylation in neuron cells, which further leads to neurodegenerative diseases such as Alzheimer's disease (AD). Therefore, there is an urgent need to find natural and safe antioxidants for preventing or treating such neurodegenerative diseases. The seeds of Trichosanthes kirilowii Maxim and T. laceribractea Hayata have long been used for medicinal and edible purposes in China. However, the antioxidant and neuroprotective activities and underlying mechanisms of their seed oils still remain unclear. Herein, we examine the antioxidant and neuroprotective effects of seed oils extracted from different germplasms, T. kirilowii (YNHH and SDJN) and T. laceribractea (ZJQT and SXHZ), on ROS levels and neuroprotective activities in C. elegans. The results demonstrated that the seed oils significantly reduced the ROS levels in C. elegans by 17.03-42.74%, with T. kirilowii (YNHH and SDJN) exhibiting significantly stronger ROS scavenging abilities than T. laceribractea (ZJQT and SXHZ). The seed oils from T. kirilowii (YNHH and SDJN) alleviated the production and aggregation of Aβ and the phosphorylation and polymerization of tau, suggesting a potential neuroprotective role. Conversely, seed oils from T. laceribractea (ZJQT and SXHZ) show minimal neuroprotective effects in C. elegans. These differential outcomes might stem from distinct mechanisms underlying antioxidant and neuroprotective effects, with the ctl-2 gene implicated as pivotal in mediating the significant neuroprotective effects of seed oils from T. kirilowii (YNHH and SDJN). Our findings have provided valuable insights into the antioxidant and neuroprotective properties of T. kirilowii seed oils, paving the way for further research aimed at elucidating the underlying mechanisms and exploring their potential therapeutic applications in combating neurodegenerative diseases.

Potential role of molecular hydrogen therapy on oxidative stress and redox signaling in chronic kidney disease

Oxidative stress plays a key role in chronic kidney disease (CKD) development and progression, inducing kidney cell damage, inflammation, and fibrosis. However, effective therapeutic interventions to slow down CKD advancement are currently lacking. The multifaceted pharmacological effects of molecular hydrogen (H2) have made it a promising therapeutic avenue. H2 is capable of capturing harmful •OH and ONOO- while maintaining the crucial reactive oxygen species (ROS) involved in cellular signaling. The NRF2-KEAP1 system, which manages cell redox balance, could be used to treat CKD. H2 activates this pathway, fortifying antioxidant defenses and scavenging ROS to counteract oxidative stress. H2 can improve NRF2 signaling by using the Wnt/β-catenin pathway and indirectly activate NRF2-KEAP1 in mitochondria. Additionally, H2 modulates NF-κB activity by regulating cellular redox status, inhibiting MAPK pathways, and maintaining Trx levels. Treatment with H2 also attenuates HIF signaling by neutralizing ROS while indirectly bolstering HIF-1α function. Furthermore, H2 affects FOXO factors and enhances the activity of antioxidant enzymes. Despite the encouraging results of bench studies, clinical trials are still limited and require further investigation. The focus of this review is on hydrogen's role in treating renal diseases, with a specific focus on oxidative stress and redox signaling regulation, and it discusses its potential clinical applications.

Protein Oxidative Modifications in Neurodegenerative Diseases: From Advances in Detection and Modelling to Their Use as Disease Biomarkers

Oxidation-reduction post-translational modifications (redox-PTMs) are chemical alterations to amino acids of proteins. Redox-PTMs participate in the regulation of protein conformation, localization and function, acting as signalling effectors that impact many essential biochemical processes in the cells. Crucially, the dysregulation of redox-PTMs of proteins has been implicated in the pathophysiology of numerous human diseases, including neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. This review aims to highlight the current gaps in knowledge in the field of redox-PTMs biology and to explore new methodological advances in proteomics and computational modelling that will pave the way for a better understanding of the role and therapeutic potential of redox-PTMs of proteins in neurodegenerative diseases. Here, we summarize the main types of redox-PTMs of proteins while providing examples of their occurrence in neurodegenerative diseases and an overview of the state-of-the-art methods used for their detection. We explore the potential of novel computational modelling approaches as essential tools to obtain insights into the precise role of redox-PTMs in regulating protein structure and function. We also discuss the complex crosstalk between various PTMs that occur in living cells. Finally, we argue that redox-PTMs of proteins could be used in the future as diagnosis and prognosis biomarkers for neurodegenerative diseases.

Advance in Iron Metabolism, Oxidative Stress and Cellular Dysfunction in Experimental and Human Kidney Diseases

Kidney diseases pose a significant global health issue, frequently resulting in the gradual decline of renal function and eventually leading to end-stage renal failure. Abnormal iron metabolism and oxidative stress-mediated cellular dysfunction facilitates the advancement of kidney diseases. Iron homeostasis is strictly regulated in the body, and disturbance in this regulatory system results in abnormal iron accumulation or deficiency, both of which are associated with the pathogenesis of kidney diseases. Iron overload promotes the production of reactive oxygen species (ROS) through the Fenton reaction, resulting in oxidative damage to cellular molecules and impaired cellular function. Increased oxidative stress can also influence iron metabolism through upregulation of iron regulatory proteins and altering the expression and activity of key iron transport and storage proteins. This creates a harmful cycle in which abnormal iron metabolism and oxidative stress perpetuate each other, ultimately contributing to the advancement of kidney diseases. The crosstalk of iron metabolism and oxidative stress involves multiple signaling pathways, such as hypoxia-inducible factor (HIF) and nuclear factor erythroid 2-related factor 2 (Nrf2) pathways. This review delves into the functions and mechanisms of iron metabolism and oxidative stress, along with the intricate relationship between these two factors in the context of kidney diseases. Understanding the underlying mechanisms should help to identify potential therapeutic targets and develop novel and effective therapeutic strategies to combat the burden of kidney diseases.

A Sequentially Activated Probe for Imaging of Superoxide Anion and Peroxynitrite in PC12 Cells under Oxidative Stress

Superoxide anion (O2·-) and peroxynitrite (ONOO-), two important oxidants under oxidative stress, coexist in complex cell and organism systems, playing crucial roles in various physiological and pathological processes, particularly in neurodegenerative diseases. Despite the absence of robust molecular tools capable of simultaneously visualizing O2·- and ONOO- in biosystems, the relationship between these two species remains understudied. Herein, we present sequentially activated fluorescent probe, DHX-SP, which exhibits exceptional selectivity and sensitivity toward O2·- and ONOO-. This probe enables precise imaging of these species in living PC12 cells under oxidative stress conditions using distinct fluorescence signal combinations. Furthermore, the probe DHX-SP has the ability to visualize changes in O2·- and ONOO- levels during ferroptosis of PC12 cells and in the Parkinson's disease model. These findings establish a connection between the crosstalk of the phosphorus group of O2·- and ONOO- in PC12 cells under oxidative stress.

Efficient Electrochemical Microsensor for the Simultaneous Measurement of Hydrogen Peroxide and Ascorbic Acid in Living Brains

Hydrogen peroxide (H2O2) and ascorbic acid (AA), acting as two significant indicative species, correlate with the oxidative stress status in living brains, which have historically been considered to be involved mainly in neurodegenerative disorders such as Alzheimer's disease, Huntington's disease, and Parkinson's disease (PD). The development of efficient biosensors for the simultaneous measurement of their levels in living brains is vital to understand their roles played in the brain and their interactive relationship in the progress of these diseases. Herein, a robust ratiometric electrochemical microsensor was rationally designed to realize the determination of H2O2 and AA simultaneously. Therefore, a specific probe was designed and synthesized with both recognition units responsible for reacting with H2O2 to produce a detectable signal on the microsensor and linkage units helping the probe modify onto the carbon substrate. A topping ingredient, single-walled carbon nanotubes (SWCNTs) was added on the surface of the electrode, with the purpose of not only facilitating the oxidation of AA but also absorbing methylene blue (MB), prompting to read out the inner reference signal. This proposed electrochemical microsensor exhibited a robust ability to real-time track H2O2 and AA in linear ranges of 0.5-900 and 10-1000 μM with high selectivity and accuracy, respectively. Eventually, the efficient electrochemical microsensor was successfully applied to the simultaneous measurement of H2O2 and AA in the rat brain, followed by microinjection, and in the PD mouse brain.

Ultra-fast genetically encoded sensor for precise real-time monitoring of physiological and pathophysiological peroxide dynamics

Hydrogen Peroxide (H2O2) is a central oxidant in redox biology due to its pleiotropic role in physiology and pathology. However, real-time monitoring of H2O2 in living cells and tissues remains a challenge. We address this gap with the development of an optogenetic hydRogen perOxide Sensor (oROS), leveraging the bacterial peroxide binding domain OxyR. Previously engineered OxyR-based fluorescent peroxide sensors lack the necessary sensitivity and response speed for effective real-time monitoring. By structurally redesigning the fusion of Escherichia coli (E. coli) ecOxyR with a circularly permutated green fluorescent protein (cpGFP), we created a novel, green-fluorescent peroxide sensor oROS-G. oROS-G exhibits high sensitivity and fast on-and-off kinetics, ideal for monitoring intracellular H2O2 dynamics. We successfully tracked real-time transient and steady-state H2O2 levels in diverse biological systems, including human stem cell-derived neurons and cardiomyocytes, primary neurons and astrocytes, and mouse brain ex vivo and in vivo. These applications demonstrate oROS's capabilities to monitor H2O2 as a secondary response to pharmacologically induced oxidative stress and when adapting to varying metabolic stress. We showcased the increased oxidative stress in astrocytes via Aβ-putriscine-MAOB axis, highlighting the sensor's relevance in validating neurodegenerative disease models. Lastly, we demonstrated acute opioid-induced generation of H2O2 signal in vivo which highlights redox-based mechanisms of GPCR regulation. oROS is a versatile tool, offering a window into the dynamic landscape of H2O2 signaling. This advancement paves the way for a deeper understanding of redox physiology, with significant implications for understanding diseases associated with oxidative stress, such as cancer, neurodegenerative, and cardiovascular diseases.

A Non-Disposable Electrochemical Sensor Based on Laser-Synthesized Pd/LIG Nanocomposite-Modified Screen-Printed Electrodes for the Detection of H2O2

There have been many studies on the significant correlation between the hydrogen peroxide content of different tissues or cells in the human body and the risk of disease, so the preparation of biosensors for detecting hydrogen peroxide concentration has been a hot topic for researchers. In this paper, palladium nanoparticles (PdNPs) and laser-induced graphene (LIG) were prepared by liquid-phase pulsed laser ablation and laser-induced technology, respectively. The complexes were prepared by stirring and used for the modification of screen-printed electrodes to develop a non-enzymatic hydrogen peroxide biosensor that is low cost and mass preparable. The PdNPs prepared with anhydrous ethanol as a solvent have a uniform particle size distribution. The LIG prepared by laser direct writing has good electrical conductivity, and its loose porous structure provides more adsorption sites. The electrochemical properties of the modified electrode were characterized by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. Compared with bare screen-printed electrodes, the modified electrodes are more sensitive for the detection of hydrogen peroxide. The sensor has a linear response range of 5 µM-0.9 mM and 0.9 mM-5 mM. The limit of detection is 0.37 µM. The above conclusions indicate that the hydrogen peroxide electrochemical biosensor prepared in this paper has great advantages and potential in electrochemical catalysis.

Structure-guided engineering of a fast genetically encoded sensor for real-time H2O2 monitoring

Hydrogen Peroxide (H2O2) is a central oxidant in redox biology due to its pleiotropic role in physiology and pathology. However, real-time monitoring of H2O2 in living cells and tissues remains a challenge. We address this gap with the development of an optogenetic hydRogen perOxide Sensor (oROS), leveraging the bacterial peroxide binding domain OxyR. Previously engineered OxyR-based fluorescent peroxide sensors lack the necessary sensitivity or response speed for effective real-time monitoring. By structurally redesigning the fusion of Escherichia coli (E. coli) ecOxyR with a circularly permutated green fluorescent protein (cpGFP), we created a novel, green-fluorescent peroxide sensor oROS-G. oROS-G exhibits high sensitivity and fast on-and-off kinetics, ideal for monitoring intracellular H2O2 dynamics. We successfully tracked real-time transient and steady-state H2O2 levels in diverse biological systems, including human stem cell-derived neurons and cardiomyocytes, primary neurons and astrocytes, and mouse neurons and astrocytes in ex vivo brain slices. These applications demonstrate oROS's capabilities to monitor H2O2 as a secondary response to pharmacologically induced oxidative stress, G-protein coupled receptor (GPCR)-induced cell signaling, and when adapting to varying metabolic stress. We showcased the increased oxidative stress in astrocytes via Aβ-putriscine-MAOB axis, highlighting the sensor's relevance in validating neurodegenerative disease models. oROS is a versatile tool, offering a window into the dynamic landscape of H2O2 signaling. This advancement paves the way for a deeper understanding of redox physiology, with significant implications for diseases associated with oxidative stress, such as cancer, neurodegenerative disorders, and cardiovascular diseases.

A biocompatible chitosan-based fluorescent polymer for efficient H2O2 detection in living cells and water samples

As a biomarker of oxidative stress, hydrogen peroxide (H2O2) plays a complex role in organisms, including regulating cell signaling, respiration, the immune system, and other life processes. Therefore, it is important to develop a tool that can simply and effectively monitor H2O2 levels in organisms and the environment. In this work, naphthalene fluorophores with a borate structure were introduced into chitosan (CTS) azide, and a CTS-based fluorescence sensor (CTS-HP) was designed for sensitive H2O2 detection. The biocompatibility and degradability of CTS endowed CTS-HP with reduced biotoxicity compared with organic fluorescent dyes, and the substitution degree of fluorophores on the CTS chains was 0.703. The randomly coiled chain structure of the CTS-HP probe enabled the boronic acid recognition sites on the fluorophores to achieve the enrichment of analyte H2O2 through a synergistic effect. Therefore, the probe CTS-HP (10 μg mL-1) exhibited a 21-fold fluorescence enhancement and good detection limit (LOD = 8.98 nM) in H2O2 solution, reaching the maximum fluorescence response faster (within 16 min). The probe also successfully achieved the fluorescence imaging of endogenous and exogenous H2O2 in zebrafish and living cells and labeled the recovery experiment of H2O2 in real water samples (recoveries rates of 90.93-102.9 % and RSD < 3.09 %).

Oxidative stress and the role of redox signalling in chronic kidney disease

Chronic kidney disease (CKD) is a major public health concern, underscoring a need to identify pathogenic mechanisms and potential therapeutic targets. Reactive oxygen species (ROS) are derivatives of oxygen molecules that are generated during aerobic metabolism and are involved in a variety of cellular functions that are governed by redox conditions. Low levels of ROS are required for diverse processes, including intracellular signal transduction, metabolism, immune and hypoxic responses, and transcriptional regulation. However, excess ROS can be pathological, and contribute to the development and progression of chronic diseases. Despite evidence linking elevated levels of ROS to CKD development and progression, the use of low-molecular-weight antioxidants to remove ROS has not been successful in preventing or slowing disease progression. More recent advances have enabled evaluation of the molecular interactions between specific ROS and their targets in redox signalling pathways. Such studies may pave the way for the development of sophisticated treatments that allow the selective control of specific ROS-mediated signalling pathways.

Glutathione Therapy in Diseases: Challenges and Potential Solutions for Therapeutic Advancement

An endogenous antioxidant, reduced glutathione (GSH), is found at high concentrations in nearly all typical cells. GSH synthesis is a controlled process, and any disruption in the process of GSH synthesis could result in GSH depletion. Cellular oxidative damage results from GSH depletion. Various pathological conditions such as aging, cardiovascular disease (CVD), psychiatric disorders, neurological disorders, liver disorders, and diabetes mellitus are more affected by this stress. There are various reasons for GSH reduction, but replenishing it can help to improve this condition. However, there are challenges in this field. Low bioavailability and poor stability of GSH limit its delivery to tissues, mainly brain tissue. Today, new approaches are used for the optimal amount and efficiency of drugs and alternative substances such as GSH. The use of nano-materials and liposomes are effective methods for improving the treatment effects of GSH. The difficulties of GSH decrease and its connection to the most important associated disorders are reviewed for the first time in this essay. The other major concerns are the molecular mechanisms involved in them; the impact of treatment with replacement GSH; the signaling pathways impacted; and the issues with alternative therapies. The utilization of nano-materials and liposomes as potential new approaches to solving these issues is being considered.

Agonists and hydrogen peroxide mediate hyperoxidation of β2-adrenergic receptor in airway epithelial cells: Implications for tachyphylaxis to β2-agonists in constrictive airway disorders

Asthma and other airway obstructive disorders are characterized by heightened inflammation and excessive airway epithelial cell reactive oxygen species (ROS), which give rise to a highly oxidative environment. After decades of use, β2-adrenergic receptor (β2AR) agonists remain at the forefront of treatment options for asthma, however, chronic use of β2-agonists leads to tachyphylaxis to the bronchorelaxant effects, a phenomenon that remains mechanistically unexplained. We have previously demonstrated that β2AR agonism increases ROS generation in airway epithelial cells, which upholds proper receptor function via feedback oxidation of β2AR cysteine thiolates to Cys-S-sulfenic acids (Cys-SOH). Our previous results also demonstrate that prevention of normal redox cycling of this post-translational oxi-modification back to the thiol prevents proper receptor function. Given that Cys-S-sulfenic acids can be irreversibly overoxidized to Cys-S-sulfinic (Cys-SO2H) or S-sulfonic (Cys-SO3H) acids, which are incapable of further participation in redox reactions, we hypothesized that β2-agonist tachyphylaxis may be explained by hyperoxidation of β2AR to S-sulfinic acids. Here, using airway epithelial cell lines and primary small airway epithelial cells from healthy and asthma-diseased donors, we show that β2AR agonism generates H2O2 in a receptor and NAPDH oxidase-dependent manner. We also demonstrate that acute and chronic receptor agonism can facilitate β2AR S-sulfination, and that millimolar H2O2 concentrations are deleterious to β2AR-mediated cAMP formation, an effect that can be rescued to a degree in the presence of the cysteine-donating antioxidant N-acetyl-L-cysteine. Our results reveal that the oxidative state of β2AR may contribute to receptor functionality and may, at least in part, explain β2-agonist tachyphylaxis.

All-optical spatiotemporal mapping of ROS dynamics across mitochondrial microdomains in situ

Hydrogen peroxide (H2O2) functions as a second messenger to signal metabolic distress through highly compartmentalized production in mitochondria. The dynamics of reactive oxygen species (ROS) generation and diffusion between mitochondrial compartments and into the cytosol govern oxidative stress responses and pathology, though these processes remain poorly understood. Here, we couple the H2O2 biosensor, HyPer7, with optogenetic stimulation of the ROS-generating protein KillerRed targeted into multiple mitochondrial microdomains. Single mitochondrial photogeneration of H2O2 demonstrates the spatiotemporal dynamics of ROS diffusion and transient hyperfusion of mitochondria due to ROS. This transient hyperfusion phenotype required mitochondrial fusion but not fission machinery. Measurement of microdomain-specific H2O2 diffusion kinetics reveals directionally selective diffusion through mitochondrial microdomains. All-optical generation and detection of physiologically-relevant concentrations of H2O2 between mitochondrial compartments provide a map of mitochondrial H2O2 diffusion dynamics in situ as a framework to understand the role of ROS in health and disease.

Pomegranate Polyphenol-Derived Injectable Therapeutic Hydrogels to Enhance Neuronal Regeneration

Drug delivery for the treatment of neurological disorders has long been considered complex due to difficulties in ensuring the drug targeting on a specific site of the damaged neural tissues and its prolonged release. A syringe-injectable polymeric hydrogel with mechanical moduli matching those of brain tissues can provide a solution to deliver the drugs to the specific region through intracranial injections in a minimally invasive manner. In this study, an injectable therapeutic hydrogel with antioxidant pomegranate polyphenols, punicalagin, is reported for efficient neuronal repair. The hydrogels composed of tyramine-functionalized hyaluronic acid and collagen crosslinked by enzymatic reactions have great injectability with high shape fidelity and effectively encapsulate the polyphenol therapeutics. Furthermore, the punicalagin continuously released from the hydrogels over several days could enhance the growth and differentiation of the neurons. Our findings for efficacy of the polyphenol therapeutic-encapsulated injectable hydrogels on neuronal regeneration would be promising for designing a new type of antioxidative biomaterials in brain disorder therapy.

Mitochondrial dysfunction and calcium dyshomeostasis in the pectoralis major muscle of broiler chickens with wooden breast myopathy

The incidence of wooden breast (WB) meat of commercial broiler chicken has been increasing in recent years. Histological examination found that the occurrence of WB myopathy was accompanied by the pectoralis major (PM) muscle damage. So far, the potential mechanisms are not fully understood. This study aimed to explore the underlying mechanism of the damage of WB-affected PM muscle caused by changes in mitochondrial function, mitochondrial redox status and Ca2+ homeostasis. A total of 80 market-age Arbor Acres male broiler chickens were sampled and categorized into control (CON) and WB groups based on the evaluation of myopathic lesions. PM muscle samples were collected (n = 8 in each group) for histopathological evaluation and biochemical analyses. Ultrastructural examination and histopathological changes suggested the occurrence of PM muscle damage in broiler chickens with WB myopathy. The WB group showed an increased level of reactive oxygen species and enhanced antioxidant capacities in mitochondria of PM muscle. These changes were related to impaired mitochondria morphology and mitochondrial dysfunction. In addition, abnormal expressions of Ca2+ channels led to substantial Ca2+ loss in SR and cytoplasmic Ca2+ overload, as well as Ca2+ accumulation in mitochondria, resulting in Ca2+ dyshomeostasis in PM muscle of broiler chickens with WB myopathy. Combined, these findings indicate that WB myopathy is related to mitochondrial dysfunction, mitochondrial redox status imbalance and Ca2+ dyshomeostasis, leading to WB-affected PM muscle damage.

Novel Near-Infrared Fluorescence Probe for Bioimaging and Evaluating Superoxide Anion Fluctuations in Ferroptosis-Mediated Epilepsy

Ferroptosis is an iron-regulated, caspase-mediated pathway of cell death that is associated with the excessive aggregation of lipid-reactive oxygen species and is extensively involved in the evolution of many diseases, including epilepsy. The superoxide anion (O2•-), as the primary precursor of ROS, is closely related to ferroptosis-mediated epilepsy. Therefore, it is crucial to establish a highly effective and convenient method for the real-time dynamic monitoring of O2•- during the ferroptosis process in epilepsy for the diagnosis and therapy of ferroptosis-mediated epilepsy. Nevertheless, no probes for detecting O2•- in ferroptosis-mediated epilepsy have been reported. Herein, we systematically conceptualized and developed a novel near-infrared (NIR) fluorescence probe, NIR-FP, for accurately tracking the fluctuation of O2•- in ferroptosis-mediated epilepsy. The probe showed exceptional sensitivity and outstanding selectivity toward O2•-. In addition, the probe has been utilized effectively to bioimage and evaluate endogenous O2•- variations in three types of ferroptosis-mediated epilepsy models (the kainic acid-induced chronic epilepsy model, the pentylenetetrazole-induced acute epilepsy model, and the pilocarpine-induced status epilepticus model). The above applications illustrated that NIR-FP could serve as a reliable and suitable tool for guiding the accurate diagnosis and therapy of ferroptosis-mediated epilepsy.

Protective Effects and Mechanisms of Pectolinarin against H2O2-Induced Oxidative Stress in SH-SY5Y Neuronal Cells

This study aims to investigate the protective effects and mechanisms of pectolinarin against oxidative stress-induced cell damage in SH-SY5Y cells. Neurodegenerative diseases-such as Alzheimer's disease-are potentially associated with oxidative stress, which causes excessive production of reactive oxygen species (ROS) that damage DNA and proteins in neuronal cells. The results of this study demonstrate that pectolinarin can scavenge hydroxyl and nitric oxide radicals in a concentration-dependent manner. Moreover, pectolinarin significantly increased cell viability while reducing ROS production and LDH release in the hydrogen peroxide (H2O2)-induced control group. Additionally, Pectolinarin recovered protein expression from H2O2-altered levels back to close-to-normal SH-SY5Y cell levels for components of the oxidative stress, inflammation, and apoptosis pathways-such as nuclear factor erythroid 2-related factor 2 (Nrf2), kelch-like ECH-associated protein (Keap1), anti-heme oxygenase 1 (HO-1), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), B-cell lympho-ma-2 (Bcl-2) protein, and Bcl-2-associated X protein (Bax). These findings suggest that pectolinarin has the potential to be used as a plant material for functional foods to be applied in the treatment of neurodegenerative diseases, such as Alzheimer's disease, by mitigating oxidative stress-induced damage to neuronal cells.

A selective fluorescent turn-on probe for imaging and sensing of hydrogen peroxide in living cells

Fluorescent turn-on probes have been extensively used in disease diagnosis and research on pathological disease mechanisms because of their low background interference. Hydrogen peroxide (H2O2) plays a vital role in regulating various cellular functions. In the current study, a fluorescent probe, HCyB, based on hemicyanine and arylboronate structures, was designed to detect H2O2. HCyB reacted with H2O2 and exhibited a good linear relationship for H2O2 concentrations ranging from 15 to 50 μM and good selectivity over other species. The fluorescent detection limit was 76 nM. Moreover, HCyB exhibited less toxicity and mitochondrial-targeting abilities. HCyB was successfully used to monitor exogenous or endogenous H2O2 in mouse macrophage RAW 264.7, human skin fibroblast WS1, breast cancer cell MDA-MB-231, and human leukemia monocytic THP1 cells.

Mitochondrial dysfunction and mitophagy: crucial players in burn trauma and wound healing

Burn injuries are a significant cause of death worldwide, leading to systemic inflammation, multiple organ failure and sepsis. The progression of burn injury is explicitly correlated with mitochondrial homeostasis, which is disrupted by the hyperinflammation induced by burn injury, leading to mitochondrial dysfunction and cell death. Mitophagy plays a crucial role in maintaining cellular homeostasis by selectively removing damaged mitochondria. A growing body of evidence from various disease models suggest that pharmacological interventions targeting mitophagy could be a promising therapeutic strategy. Recent studies have shown that mitophagy plays a crucial role in wound healing and burn injury. Furthermore, chemicals targeting mitophagy have also been shown to improve wound recovery, highlighting the potential for novel therapeutic strategies based on an in-depth exploration of the molecular mechanisms regulating mitophagy and its association with skin wound healing.

Redox Imbalance in Neurological Disorders in Adults and Children

Oxygen is a central molecule for numerous metabolic and cytophysiological processes, and, indeed, its imbalance can lead to numerous pathological consequences. In the human body, the brain is an aerobic organ and for this reason, it is very sensitive to oxygen equilibrium. The consequences of oxygen imbalance are especially devastating when occurring in this organ. Indeed, oxygen imbalance can lead to hypoxia, hyperoxia, protein misfolding, mitochondria dysfunction, alterations in heme metabolism and neuroinflammation. Consequently, these dysfunctions can cause numerous neurological alterations, both in the pediatric life and in the adult ages. These disorders share numerous common pathways, most of which are consequent to redox imbalance. In this review, we will focus on the dysfunctions present in neurodegenerative disorders (specifically Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis) and pediatric neurological disorders (X-adrenoleukodystrophies, spinal muscular atrophy, mucopolysaccharidoses and Pelizaeus-Merzbacher Disease), highlighting their underlining dysfunction in redox and identifying potential therapeutic strategies.

Thyroid-Disrupting Effects of Exposure to Fipronil and Its Metabolites from Drinking Water Based on Human Thyroid Follicular Epithelial Nthy-ori 3-1 Cell Lines

Fipronil is a broad-spectrum insecticide used for plants and poultry. Owing to its widespread use, fipronil and its metabolites (fipronil sulfone, fipronil desulfinyl, and fipronil sulfide), termed FPM, can be frequently detected in drinking water and food. Fipronil can affect the thyroid function of animals, but the effects of FPM on the human thyroid remain unclear. We employed human thyroid follicular epithelial Nthy-ori 3-1 cells to examine combined cytotoxic responses, thyroid-related functional proteins including the sodium-iodide symporter (NIS), thyroid peroxidase (TPO), deiodinases I-III (DIO I-III), and the nuclear factor erythroid-derived factor 2-related factor 2 (NRF2) pathway induced by FPM of 1-1000-fold concentrations detected in school drinking water collected from a heavily contaminated area of the Huai River Basin. Thyroid-disrupting effects of FPM were evaluated by examining biomarkers of oxidative stress and thyroid function and tetraiodothyronine (T4) levels secreted by Nthy-ori 3-1 cells after FPM treatment. FPM activated the expression of NRF2, HO-1 (heme oxygenase 1), TPO, DIO I, and DIO II but inhibited NIS expression and increased the T4 level of thyrocytes, indicating that FPM can disrupt the function of human thyrocytes through oxidative pathways. Given the adverse impact of low FPM concentrations on human thyrocytes, supportive evidence from rodent studies, and the critical importance of thyroid hormones on development, the effects of FPM on the neurodevelopment and growth of children warrant priority attention.

Redox Modulation of Mitochondrial Proteins in the Neurotoxicant Models of Parkinson's Disease

Significance: Mitochondrial proteins regulate the oxidative phosphorylation, cellular metabolism, and free radical generation. Redox modulation alters the mitochondrial proteins and instigates the damage to dopaminergic neurons. Toxicants contribute to Parkinson's disease (PD) pathogenesis in conjunction with aging and genetic factors. While oxidative modulation of a number of mitochondrial proteins is linked to xenobiotic exposure, little is known about its role in the toxicant-induced PD. Understanding the role of redox modulation of mitochondrial proteins in complex cellular events leading to neurodegeneration is highly relevant. Recent Advances: Many toxicants are shown to inhibit complex I or III and elicit free radical production that alters the redox status of mitochondrial proteins. Implication of redox modulation of the mitochondrial proteins makes them a target to comprehend the underlying mechanism of toxicant-induced PD. Critical Issues: Owing to multifactorial etiology, exploration of onset and progression and treatment outcomes needs a comprehensive approach. The article explains about a few mitochondrial proteins that undergo redox changes along with the promising strategies, which help to alleviate the toxicant-induced redox imbalance leading to neurodegeneration. Future Directions: Although mitochondrial proteins are linked to PD, their role in toxicant-induced parkinsonism is not yet completely known. Preservation of antioxidant defense machinery could alleviate the redox modulation of mitochondrial proteins. Targeted antioxidant delivery, use of metal chelators, and activation of nuclear factor erythroid 2-related factor 2, and combinational therapy that encounters multiple free radicals, could ameliorate the redox modulation of mitochondrial proteins and thereby PD progression.

Lipid peroxidation and sphingolipid alterations in the cerebral cortex and hypothalamus of rats fed a high-protein diet

OBJECTIVES

High-protein diets (HPDs) are widely accepted to enhance satiety and energy expenditure and thus have become a popular strategy to lose weight and facilitate muscle protein synthesis. However, long-term high-protein consumption could be linked with metabolic and clinical problems such as renal and liver dysfunctions. This study verified the effects of 8-wk high-protein ingestion on lipid peroxidation and sphingolipid metabolism in the plasma, cerebral cortex, and hypothalamus in rats.

METHODS

Immunoenzymatic and spectrophotometric methods were applied to assess oxidation-reduction (redox) biomarkers and neutral sphingomyelinase activity, whereas gas-liquid chromatography and high-performance liquid chromatography were used to examine sphingolipid levels.

RESULTS

The vast majority of HPD-related alterations was restricted to the hypothalamus. Specifically, an increased rate of lipid peroxidation (increased lipid hydroperoxides, 8-isoprostanes, and thiobarbituric acid reactive substances) associated with ceramide accumulation via the activation of de novo synthesis (decreased sphinganine), salvage pathway (decreased sphingosine), and sphingomyelin hydrolysis (decreased sphingomyelin and increased neutral sphingomyelinase activity) was noted.

CONCLUSIONS

This study showed that HPD substantially affected hypothalamic metabolic pathways, which potentially alter cerebral output signals to the peripheral tissues.

Rotenone-induced oxidative stress in THP-1 cells: biphasic effects of baicalin

BACKGROUND

Several results demonstrated that microglia and peripheral monocytes/macrophages infiltrating the central nervous system (CNS) are involved in cell response against toxic compounds. It has been shown that rotenone induces neurodegeneration in various in vitro experimental models. Baicalin, a natural compound, is able to attenuate cell damage through anti-oxidant, anti-microbial, anti-inflammatory, and immunomodulatory action. Using THP-1 monocytes, we investigated rotenone effects on mitochondrial dysfunction and apoptosis, as well as baicalin ability to counteract rotenone toxicity.

METHODS AND RESULTS

THP-1 cells were exposed to rotenone (250 nM), in the presence/absence of baicalin (10-500 μM) for 2-24 h. Reactive Oxygen Species production (ROS), mitochondrial activity and transmembrane potential (Δψm), DNA damage, and caspase-3 activity were assessed. Moreover, gene expression of mitochondrial transcription factor a (mtTFA), interleukin-1β (IL-1β), B-cell lymphoma 2 (Bcl2) and BCL2-associated X protein (Bax), together with apoptotic morphological changes, were evaluated. After 2 h of rotenone incubation, increased ROS production and altered Δψm were observed, hours later resulting in DNA oxidative damage and apoptosis. Baicalin treatment at 50 µM counteracted rotenone toxicity by modulating the expression levels of some proteins involved in mitochondrial biogenesis and apoptosis. Interestingly, at higher baicalin concentrations, rotenone-induced alterations persisted.

CONCLUSIONS

These results give evidence that exposure to rotenone may promote the activation of THP-1 monocytes contributing to enhanced neurodegeneration. In this context, baicalin at low concentration exerts beneficial effects on mitochondrial function, and thus may prevent the onset of neurotoxic processes.

Real-Time Monitoring of Hydrogen Peroxide Levels in Yeast and Mammalian Cells

Hydrogen peroxide (H2O2) is an important signaling molecule involved in regulating antioxidative transcriptional responses, cellular differentiation, and hypoxia response. H2O2 generation and signaling are highly localized processes. Understanding the dynamics of this molecule inside intact cells with subcompartmental resolution is instrumental to unravel its role in cellular signaling. Different genetically encoded fluorescent sensors have been developed over the last few years that enable such non-disruptive monitoring with high spatiotemporal resolution. In this chapter, we describe the use of these genetically encoded sensors to directly monitor H2O2 dynamics in yeast and cultured mammalian cells.

Oxidative Stress and Extracellular Matrix Remodeling Are Signature Pathways of Extracellular Vesicles Released upon Morphine Exposure on Human Brain Microvascular Endothelial Cells

Morphine, a commonly used antinociceptive drug in hospitals, is known to cross the blood-brain barrier (BBB) by first passing through brain endothelial cells. Despite its pain-relieving effect, morphine also has detrimental effects, such as the potential induction of redox imbalance in the brain. However, there is still insufficient evidence of these effects on the brain, particularly on the brain endothelial cells and the extracellular vesicles that they naturally release. Indeed, extracellular vesicles (EVs) are nanosized bioparticles produced by almost all cell types and are currently thought to reflect the physiological state of their parent cells. These vesicles have emerged as a promising source of biomarkers by indicating the functional or dysfunctional state of their parent cells and, thus, allowing a better understanding of the biological processes involved in an adverse state. However, there is very little information on the morphine effect on human brain microvascular endothelial cells (HBMECs), and even less on their released EVs. Therefore, the current study aimed at unraveling the detrimental mechanisms of morphine exposure (at 1, 10, 25, 50 and 100 µM) for 24 h on human brain microvascular endothelial cells as well as on their associated EVs. Isolation of EVs was carried out using an affinity-based method. Several orthogonal techniques (NTA, western blotting and proteomics analysis) were used to validate the EVs enrichment, quality and concentration. Data-independent mass spectrometry (DIA-MS)-based proteomics was applied in order to analyze the proteome modulations induced by morphine on HBMECs and EVs. We were able to quantify almost 5500 proteins in HBMECs and 1500 proteins in EVs, of which 256 and 148, respectively, were found to be differentially expressed in at least one condition. Pathway enrichment analysis revealed that the "cell adhesion and extracellular matrix remodeling" process and the "HIF1 pathway", a pathway related to oxidative stress responses, were significantly modulated upon morphine exposure in HBMECs and EVs. Altogether, the combination of proteomics and bioinformatics findings highlighted shared pathways between HBMECs exposed to morphine and their released EVs. These results put forward molecular signatures of morphine-induced toxicity in HBMECs that were also carried by EVs. Therefore, EVs could potentially be regarded as a useful tool to investigate brain endothelial cells dysfunction, and to a different extent, the BBB dysfunction in patient circulation using these "signature pathways".

COA-Cl Evokes Protective Responses Against H2O2-and 6-OHDA-Induced Toxic Injury in PC12 Cells

COA-Cl, a novel adenosine-like nucleic acid analog, has recently been shown to exert neuroprotective effects and to increase dopamine levels both in vivo and in vitro. Therefore, we hypothesized that COA-Cl could protect dopaminergic neurons against toxic insults. Thus, the present study aimed to investigate the protective effects of COA-Cl against hydrogen peroxide (H₂O₂)- and 6-hydroxydopamine (6-OHDA)-induced toxicity in PC12 cells and to elucidate the possible mechanisms. PC12 cells were incubated with COA-Cl (100 μM) with or without H₂O₂ or 6-OHDA (200 μM) for 24 h. Treatment with COA-Cl attenuated the decrease in cell viability, SOD activity and the Bcl-2/Bax ratio caused by H₂O₂. In addition, COA-Cl attenuated the increase in LDH release, ROS production, caspase-3 activity, and apoptosis induced by H₂O₂. Further, COA-Cl enhanced the protection of PC12 cells against the toxicity caused by 6-OHDA, as evidenced by an increase in cell viability and the Bcl-2/Bax ratio, and a decrease in LDH release. Our results are the first to demonstrate that COA-Cl potentially protects PC12 cells against toxicity induced by H₂O₂ and 6-OHDA, implying that COA-Cl could be a promising neuroprotective agent for the treatment of Parkinson's disease.

The 2022 Lady Estelle Wolfson lectureship on neurofilaments

Neurofilament proteins (Nf) have been validated and established as a reliable body fluid biomarker for neurodegenerative pathology. This review covers seven Nf isoforms, Nf light (NfL), two splicing variants of Nf medium (NfM), two splicing variants of Nf heavy (NfH),α -internexin (INA) and peripherin (PRPH). The genetic and epigenetic aspects of Nf are discussed as relevant for neurodegenerative diseases and oncology. The comprehensive list of mutations for all Nf isoforms covers Amyotrophic Lateral Sclerosis, Charcot-Marie Tooth disease, Spinal muscular atrophy, Parkinson Disease and Lewy Body Dementia. Next, emphasis is given to the expanding field of post-translational modifications (PTM) of the Nf amino acid residues. Protein structural aspects are reviewed alongside PTMs causing neurodegenerative pathology and human autoimmunity. Molecular visualisations of NF PTMs, assembly and stoichiometry make use of Alphafold2 modelling. The implications for Nf function on the cellular level and axonal transport are discussed. Neurofilament aggregate formation and proteolytic breakdown are reviewed as relevant for biomarker tests and disease. Likewise, Nf stoichiometry is reviewed with regard to in vitro experiments and as a compensatory mechanism in neurodegeneration. The review of Nf across a spectrum of 87 diseases from all parts of medicine is followed by a critical appraisal of 33 meta-analyses on Nf body fluid levels. The review concludes with considerations for clinical trial design and an outlook for future research.

CADMA-Chem: A Computational Protocol Based on Chemical Properties Aimed to Design Multifunctional Antioxidants

A computational protocol aimed to design new antioxidants with versatile behavior is presented. It is called Computer-Assisted Design of Multifunctional Antioxidants and is based on chemical properties (CADMA-Chem). The desired multi-functionality consists of in different methods of antioxidant protection combined with neuroprotection, although the protocol can also be used to pursue other health benefits. The dM38 melatonin derivative is used as a study case to illustrate the protocol in detail. This was found to be a highly promising candidate for the treatment of neurodegeneration, in particular Parkinson's and Alzheimer's diseases. This also has the desired properties of an oral-drug, which is significantly better than Trolox for scavenging free radicals, and has chelates redox metals, prevents the ●OH production, via Fenton-like reactions, repairs oxidative damage in biomolecules (lipids, proteins, and DNA), and acts as a polygenic neuroprotector by inhibiting catechol-O-methyl transferase (COMT), acetylcholinesterase (AChE) and monoamine oxidase B (MAOB). To the best of our best knowledge, CADMA-Chem is currently the only protocol that simultaneously involves the analyses of drug-like behavior, toxicity, manufacturability, versatile antioxidant protection, and receptor-ligand binding affinities. It is expected to provide a starting point that helps to accelerate the discovery of oral drugs with the potential to prevent, or slow down, multifactorial human health disorders.

Synthesis and characterization of protocatechuic acid grafted carboxymethyl chitosan with oxidized sodium alginate hydrogel through the Schiff's base reaction

Excessive accumulation of free radicals is closely related to the occurrence and development of various neurodegenerative diseases. In this study, a novel protocatechuic acid grafted carboxymethyl chitosan with oxidized sodium alginate (PCA-g-CMCS/OSA) hydrogel was developed to maintain the oxidation-antioxidation balance activities. By optimizing the pH-soluble range (pH > 6.4) of CMCS, PCA was grafted onto CMCS skeleton via EDC/NHS, and then conjugated with aldehyde group of OSA to form Schiff's base hydrogel at physiological temperature. The gelation time can be adjusted rapidly within 1-3 min by controlling the content of OSA. The shaped hydrogel exhibited porous network structure with high porosity (>90 %), swelling ratio (2000-3000 %) and rheological property, which is beneficial to cell growth and proliferation. The conjugates preserved excellent DPPH and ABTS radicals scavenging abilities and adequate biodegradability within 5 weeks. Moreover, with the release of PCA monomer due to degradation of the PCA-g-CMCS/OSA, the hydrogel also exhibited excellent biocompatibility and protective effect on H2O2-induced oxidative damage in PC12 cells. These results suggested that the PCA-g-CMCS/OSA hydrogel would appear to be a more attractive candidate for potential biomedical applications such as antioxidant drug release and tissue engineering implant material.

Pridopidine Promotes Synaptogenesis and Reduces Spatial Memory Deficits in the Alzheimer's Disease APP/PS1 Mouse Model

Sigma-1 receptor agonists have recently gained a great deal of interest due to their anti-amnesic, neuroprotective, and neurorestorative properties. Compounds such as PRE-084 or pridopidine (ACR16) are being studied as a potential treatment against cognitive decline associated with neurodegenerative disease, also to include Alzheimer's disease. Here, we performed in vitro experiments using primary neuronal cell cultures from rats to evaluate the abilities of ACR16 and PRE-084 to induce new synapses and spines formation, analyzing the expression of the possible genes and proteins involved. We additionally examined their neuroprotective properties against neuronal death mediated by oxidative stress and excitotoxicity. Both ACR16 and PRE-084 exhibited a concentration-dependent neuroprotective effect against NMDA- and H2O2-related toxicity, in addition to promoting the formation of new synapses and dendritic spines. However, only ACR16 generated dendritic spines involved in new synapse establishment, maintaining a more expanded activation of MAPK/ERK and PI3K/Akt signaling cascades. Consequently, ACR16 was also evaluated in vivo, and a dose of 1.5 mg/kg/day was administered intraperitoneally in APP/PS1 mice before performing the Morris water maze. ACR16 diminished the spatial learning and memory deficits observed in APP/PS1 transgenic mice via PI3K/Akt pathway activation. These data point to ACR16 as a pharmacological tool to prevent synapse loss and memory deficits associated with Alzheimer's disease, due to its neuroprotective properties against oxidative stress and excitotoxicity, as well as the promotion of new synapses and spines through a mechanism that involves AKT and ERK signaling pathways.

Role of Reactive Oxygen Species in Aging and Age-Related Diseases: A Review

Research on the role of reactive oxygen species (ROS) in the aging process has advanced significantly over the last two decades. In light of recent findings, ROS takes part in the aging process of cells along with contributing to various physiological signaling pathways. Antioxidants being cells' natural defense mechanism against ROS-mediated alteration, play an imperative role to maintain intracellular ROS homeostasis. Although the complete understanding of the ROS regulated aging process is yet to be fully comprehended, current insights into various sources of cellular ROS and their correlation with the aging process and age-related diseases are portrayed in this review. In addition, results on the effect of antioxidants on ROS homeostasis and the aging process as well as their advances in clinical trials are also discussed in detail. The future perspective in ROS-antioxidant dynamics on antiaging research is also marshaled to provide future directions for ROS-mediated antiaging research fields.

Natural Antioxidant Compounds as Potential Pharmaceutical Tools against Neurodegenerative Diseases

Natural antioxidants are a very large diversified family of molecules classified by activity (enzymatic or nonenzymatic), chemical-physical properties (e.g., hydrophilic or lipophilic), and chemical structure (e.g., vitamins, polyphenols, etc.). Research on natural antioxidants in various fields, such as pharmaceutics, nutraceutics, and cosmetics, is among the biggest challenges for industry and science. From a biomedical point of view, the scavenging activity of reactive oxygen species (ROS) makes them a potential tool for the treatment of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, dementia, and amyotrophic lateral sclerosis (ALS). In addition to the purified phytochemical compounds, a variety of natural extracts characterized by a complex mixture of antioxidants and anti-inflammatory molecules have been successfully exploited to rescue preclinical models of these diseases. Extracts derived from Ginkgo biloba, grape, oregano, curcumin, tea, and ginseng show multitherapeutic effects by synergically acting on different biochemical pathways. Furthermore, the reduced toxicity associated with many of these compounds limits the occurrence of side effects. The support of nanotechnology for improving brain delivery, controlling release, and preventing rapid degradation and excretion of these compounds is of fundamental importance. This review reports on the most promising results obtained on in vitro systems, in vivo models, and in clinical trials, by exploiting natural-derived antioxidant compounds and extracts, in their free form or encapsulated in nanocarriers.

Asiatic acid attenuates aluminium chloride-induced behavioral changes, neuronal loss and astrocyte activation in rats

Aluminium (Al) is a potent neurotoxic metal known to cause neurodegeneration. Al exposure causes oxidative stress by accumulation of reactive oxygen species, followed by the activation of neuronal cell death in the brain. Asiatic acid (AA), the major bioactive compound of Centella asiatica (a medicinal plant), act as multifunctional drug as well as an antioxidant. Thus, the present study aimed to investigate the potential neuroprotective effect of AA against Al neurotoxicity. Rats were orally administered aluminium chloride (AlCl₃; 100 mg/kg b. wt.) dissolved in distilled water for 8 weeks or AA (75 mg/kg b. wt.) in combination with AlCl₃. The results showed that AlCl₃-intoxication causes significant impairment of memory, enhances anxiety-like behavior, acetyl cholinesterase (AChE) activity, malondialdehydes (MDA) level, and concomitant decrease in the activities of superoxide dismutase (SOD) and catalase (CAT) in the cortex and hippocampus regions of rat brain. In addition, AlCl₃-intoxication enhanced neuronal loss and reactive astrogliosis in both regions. However, co-administration of AA with AlCl₃ significantly attenuated the behavioral alterations, restored SOD and CAT activities, while reduced AChE activity and MDA content. Further, the study demonstrated that AA attenuates neuronal loss and reactive astrogliosis in rat brain. In conclusion, the study suggests that AA protects rat brain from Al neurotoxicity by inhibiting oxidative stress, neuronal loss and reactive astrogliosis.

VDAC1 regulates neuronal cell loss after retinal trauma injury by a mitochondria-independent pathway

The voltage-dependent anion channel 1 (VDAC1) was first described as a mitochondrial porin that mediates the flux of metabolites and ions, thereby integrating both cell survival and death signals. In the nervous system, the functional roles of VDAC1 remain poorly understood. Herein, the rat retina was employed to study VDAC1. First, it was observed that even subtle changes in VDAC1 levels affect neuronal survival, inducing severe alterations in the retinal morphology. We next examined the regulation of VDAC1 after traumatic retinal injury. After mechanical trauma, SOD1 translocates towards the nucleus, which is insufficient to contain the consequences of oxidative stress, as determined by the evaluation of protein carbonylation. Using in vitro models of oxidative stress and mechanical injury in primary retinal cell cultures, it was possible to determine that inhibition of VDAC1 oligomerization by 4'-diisothiocyano-2,2'-disulfonic acid stilbene (DIDS) rescues cell viability, impacting microglial cell activation. We next focused on the regulation of VDAC1 after retinal mechanical injury. VDAC1 was promptly upregulated 2 h after lesion in the plasma membrane and endoplasmic reticulum rather than in the mitochondria, and multimers of VDAC1 were assembled after lesion. DIDS intraocular application decreased apoptosis and prevented microglial polarization, which confirmed in vitro observations. Considering the role of microglia in neuroinflammation, multiplex evaluation of cytokines showed that DIDS application disorganized the inflammatory response 2 h after the lesion, matching the fast regulation of VDAC1. Taken together, data disclosed that fine regulation of VDAC1 influences neuronal survival, and pharmacological inhibition after trauma injury has neuroprotective effects. This protection may be attributed to the effects on VDAC1 abnormal accumulation in the plasma membrane, thereby controlling the activation of microglial cells. We concluded that VDAC1 is a putative therapeutic target in neuronal disorders since it integrates both death and survival cellular signaling.

On the origin of chaotrope-modulated electrocatalytic activity of cytochrome c at electrified aqueous|organic interfaces

Electrochemical, spectroscopic and computational methods are used to demonstrate that electrified aqueous|organic interfaces are a suitable bio-mimetic platform to study and contrast the accelerated electrocatalytic activity of cytochrome c towards the production of reactive oxygen species (ROS) in the presence of denaturing agents such as guanidinium chloride and urea.

Intercellular Communication in the Brain through Tunneling Nanotubes

Simple Summary

Tunneling nanotubes (TNTs) are a means of cell communication which have been recently discovered. They allow the intercellular trafficking of many types of cellular compounds ranging from ions, such as Ca²⁺, to whole organelles such as mitochondria. TNTs are found in many tissues, both in physiological and pathological conditions. They are also found in the brain where they contribute to brain development and function and also to degenerative diseases and glioma.

Abstract

Intercellular communication is essential for tissue homeostasis and function. Understanding how cells interact with each other is paramount, as crosstalk between cells is often dysregulated in diseases and can contribute to their progression. Cells communicate with each other through several modalities, including paracrine secretion and specialized structures ensuring physical contact between them. Among these intercellular specialized structures, tunneling nanotubes (TNTs) are now recognized as a means of cell-to-cell communication through the exchange of cellular cargo, controlled by a variety of biological triggers, as described here. Intercellular communication is fundamental to brain function. It allows the dialogue between the many cells, including neurons, astrocytes, oligodendrocytes, glial cells, microglia, necessary for the proper development and function of the brain. We highlight here the role of TNTs in connecting these cells, for the physiological functioning of the brain and in pathologies such as stroke, neurodegenerative diseases, and gliomas. Understanding these processes could pave the way for future therapies.