Environmental-induced oxidative stress in neurodegenerative disorders and aging

A Review: Multi-Omics Approach to Studying the Association between Ionizing Radiation Effects on Biological Aging

Multi-omics studies have emerged as powerful tools for tailoring individualized responses to various conditions, capitalizing on genome sequencing technologies' increasing affordability and efficiency. This paper delves into the potential of multi-omics in deepening our understanding of biological age, examining the techniques available in light of evolving technology and computational models. The primary objective is to review the relationship between ionizing radiation and biological age, exploring a wide array of functional, physiological, and psychological parameters. This comprehensive review draws upon an extensive range of sources, including peer-reviewed journal articles, government documents, and reputable websites. The literature review spans from fundamental insights into radiation effects to the latest developments in aging research. Ionizing radiation exerts its influence through direct mechanisms, notably single- and double-strand DNA breaks and cross links, along with other critical cellular events. The cumulative impact of DNA damage forms the foundation for the intricate process of natural aging, intersecting with numerous diseases and pivotal biomarkers. Furthermore, there is a resurgence of interest in ionizing radiation research from various organizations and countries, reinvigorating its importance as a key contributor to the study of biological age. Biological age serves as a vital reference point for the monitoring and mitigation of the effects of various stressors, including ionizing radiation. Ionizing radiation emerges as a potent candidate for modeling the separation of biological age from chronological age, offering a promising avenue for tailoring protocols across diverse fields, including the rigorous demands of space exploration.

Arsenic Exposure and Epigenetic Aging: The Association with Cardiovascular Disease and All-Cause Mortality in the Strong Heart Study

BACKGROUND

Inorganic arsenic (As) may increase the risk of cardiovascular disease (CVD) and all-cause mortality through accelerated aging, which can be estimated using epigenetic-based measures.

OBJECTIVES

We evaluated three DNA methylation-based aging measures (PhenoAge, GrimAge, DunedinPACE) (epigenetic aging measures) as potential mediators of the previously reported association of As exposure with CVD incidence, CVD mortality, and all-cause mortality in the Strong Heart Study (SHS), an epidemiological cohort of American Indian adults.

METHODS

Blood DNA methylation and urinary As levels were measured in 2,323 SHS participants (41.5% men, mean age of 55 years old). PhenoAge and GrimAge values were calculated using a residual-based method. We tested the association of urinary As with epigenetic aging measures using linear regression, the association of epigenetic aging measures with the three health outcomes using additive hazards models, and the mediation of As-related CVD incidence, CVD mortality, and all-cause mortality by epigenetic aging measures using the product of coefficients method.

RESULTS

SHS participants with higher vs. lower urinary As levels had similar PhenoAge age, older GrimAge age, and faster DunedinPACE. An interquartile range increase in urinary As was associated with higher of PhenoAge age acceleration [mean difference  ( 95 %  confidence interval ) = 0.48 (0.17, 0.80) years], GrimAge age acceleration [0.80 (0.60, 1.00) years], and DunedinPACE [0.011 (0.005, 0.018)], after adjusting for age, sex, center location, genetic components, smoking status, and body mass index. Of the 347 incident CVD events per 100,000 person-years associated with a doubling in As exposure, 21.3% (9.1, 57.1) and 22.6% (9.5, 56.9), were attributable to differences in GrimAge and DunedinPACE, respectively.

DISCUSSION

Arsenic exposure was associated with older GrimAge and faster DunedinPACE measures of biological age. Furthermore, accelerated biological aging measured from DNA methylation accounted for a relevant fraction of As-associated risk for CVD, CVD mortality, and all-cause mortality in the SHS, supporting the role of As in accelerated aging. Research of the biological underpinnings can contribute to a better understanding of the role of aging in arsenic-related disease. https://doi.org/10.1289/EHP11981.

Quantifying telomere transcripts as tool to improve risk assessment for genetic instability and genotoxicity

Telomere repeat-containing RNAs (TERRA) are transcribed from telomeres as long non-coding RNAs and are part of the telomere structure with protective function. The genetic stability of cells requires telomeric repeats at the ends of chromosomes. Maintenance of telomere length (TL) is essential for proliferative capacity and chromosomal integrity. In contrast, telomere shortening is a recognized risk factor for carcinogenesis and a biomarker of aging due to the cumulative effects of environmental exposures and life experiences such as trauma or stress. In this context, telomere repeats are lost due to cell proliferation, but are also susceptible to stress factors including reactive oxygen species (ROS) inducing oxidative base damage. Quantitative PCR (qPCR) of genomic DNA is an established method to analyze TL as a tool to detect genotoxic events. That same qPCR method can be applied to RNA converted into cDNA to quantify TERRA as a useful tool to perform high-throughput screenings. This short review summarizes relevant qPCR studies using both TL and TERRA quantification, provides an overall view of the molecular mechanisms of telomere protection against ROS by TERRA, and summarizes the presented studies comparing the results at DNA and RNA levels, which indicate that fluctuations at transcript level might reflect a short-term response. Therefore, we conclude that performing both of these measurements together will improve genotoxicity studies.

Morphometric and Nanomechanical Screening of Peripheral Blood Cells with Atomic Force Microscopy for Label-Free Assessment of Alzheimer's Disease, Parkinson's Disease, and Amyotrophic Lateral Sclerosis

Neurodegenerative disorders (NDDs) are complex, multifactorial disorders with significant social and economic impact in today's society. NDDs are predicted to become the second-most common cause of death in the next few decades due to an increase in life expectancy but also to a lack of early diagnosis and mainly symptomatic treatment. Despite recent advances in diagnostic and therapeutic methods, there are yet no reliable biomarkers identifying the complex pathways contributing to these pathologies. The development of new approaches for early diagnosis and new therapies, together with the identification of non-invasive and more cost-effective diagnostic biomarkers, is one of the main trends in NDD biomedical research. Here we summarize data on peripheral biomarkers, biofluids (cerebrospinal fluid and blood plasma), and peripheral blood cells (platelets (PLTs) and red blood cells (RBCs)), reported so far for the three most common NDDs-Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). PLTs and RBCs, beyond their primary physiological functions, are increasingly recognized as valuable sources of biomarkers for NDDs. Special attention is given to the morphological and nanomechanical signatures of PLTs and RBCs as biophysical markers for the three pathologies. Modifications of the surface nanostructure and morphometric and nanomechanical signatures of PLTs and RBCs from patients with AD, PD, and ALS have been revealed by atomic force microscopy (AFM). AFM is currently experiencing rapid and widespread adoption in biomedicine and clinical medicine, in particular for early diagnostics of various medical conditions. AFM is a unique instrument without an analog, allowing the generation of three-dimensional cell images with extremely high spatial resolution at near-atomic scale, which are complemented by insights into the mechanical properties of cells and subcellular structures. Data demonstrate that AFM can distinguish between the three pathologies and the normal, healthy state. The specific PLT and RBC signatures can serve as biomarkers in combination with the currently used diagnostic tools. We highlight the strong correlation of the morphological and nanomechanical signatures between RBCs and PLTs in PD, ALS, and AD.

Bilirubin and Redox Stress in Age-Related Brain Diseases

Cellular redox status has a crucial role in brain physiology, as well as in pathologic conditions. Physiologic senescence, by dysregulating cellular redox homeostasis and decreasing antioxidant defenses, enhances the central nervous system's susceptibility to diseases. The reduction of free radical accumulation through lifestyle changes, and the supplementation of antioxidants as a prophylactic and therapeutic approach to increase brain health, are strongly suggested. Bilirubin is a powerful endogenous antioxidant, with more and more recognized roles as a biomarker of disease resistance, a predictor of all-cause mortality, and a molecule that may promote health in adults. The alteration of the expression and activity of the enzymes involved in bilirubin production, as well as an altered blood bilirubin level, are often reported in neurologic conditions and neurodegenerative diseases (together denoted NCDs) in aging. These changes may predict or contribute both positively and negatively to the diseases. Understanding the role of bilirubin in the onset and progression of NCDs will be functional to consider the benefits vs. the drawbacks and to hypothesize the best strategies for its manipulation for therapeutic purposes.

Redox dysregulation as a driver for DNA damage and its relationship to neurodegenerative diseases

Redox homeostasis refers to the balance between the production of reactive oxygen species (ROS) as well as reactive nitrogen species (RNS), and their elimination by antioxidants. It is linked to all important cellular activities and oxidative stress is a result of imbalance between pro-oxidants and antioxidant species. Oxidative stress perturbs many cellular activities, including processes that maintain the integrity of DNA. Nucleic acids are highly reactive and therefore particularly susceptible to damage. The DNA damage response detects and repairs these DNA lesions. Efficient DNA repair processes are therefore essential for maintaining cellular viability, but they decline considerably during aging. DNA damage and deficiencies in DNA repair are increasingly described in age-related neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and Huntington's disease. Furthermore, oxidative stress has long been associated with these conditions. Moreover, both redox dysregulation and DNA damage increase significantly during aging, which is the biggest risk factor for neurodegenerative diseases. However, the links between redox dysfunction and DNA damage, and their joint contributions to pathophysiology in these conditions, are only just emerging. This review will discuss these associations and address the increasing evidence for redox dysregulation as an important and major source of DNA damage in neurodegenerative disorders. Understanding these connections may facilitate a better understanding of disease mechanisms, and ultimately lead to the design of better therapeutic strategies based on preventing both redox dysregulation and DNA damage.

Biological activity of algal derived carrageenan: A comprehensive review in light of human health and disease

Carrageenans are a family of natural linear sulfated polysaccharides derived from red seaweeds and used as a common food additive. Carrageenan's properties, impact on health, and aesthetic benefits have all been studied for a long time; however, the mechanisms are still unclear. In pharmaceutical aspects, carrageenan displayed potential antioxidant and immunomodulatory properties in both in vivo and in vitro action. It also contributes to potential disease-preventive activities through dynamic modulation of important intracellular signaling pathways, regulation of ROS buildup, and preservation of major cell survival and death processes which leads to potential drug development. Furthermore, the chemical synthesis of the current bioactive medicine with confirmational rearrangement may increase availability and bioactivity needs diligent examination. In this review, we give an up-to-date overview of recent research on Carrageenan with reference to health and therapeutic advantages. In addition, we have focused on structural conformation and its primary strategic deployment in disease prevention, as well as the mechanistic investigation of how it functions to combat various disease-preventive employed for future therapeutic interventions. This review may get new insights into the possible novel role of carrageenan and open up a novel disease-preventive mechanism and enhance human health.

Serum NOX1 and Raftlin as new potential biomarkers of Major Depressive Disorder: A study in treatment-naive first episode patients

INTRODUCTION

Biological factors are known to be important in understanding the pathogenesis of Major Depressive Disorder (MDD). Oxidative stress and neuroinflammation pathways are likely to play a critical role here.

METHODS

We undertook a study to investigate two novel biomarkers - serum NADPH oxidase 1 (NOX1) and Raftlin levels - in treatment-naive, smoking-free first episode patients with MDD compared to healthy controls (HCs) matched for age, sex and body mass index.

RESULTS

We found increased NOX1 and Raftlin levels in MDD patients compared to HCs. Both parameters showed very good diagnostic performance in the MDD group. In addition, we found a significant positive correlation between depression severity (HAMD) scores and both biomarker levels in the patient group.

CONCLUSION

To the best of our knowledge, this is the first human study to evaluate serum NOX1 and Raftlin levels in depression. NOX1, an important source of reactive oxygen species (ROS), and Raftlin, which may play a role in the inflammatory process, represent novel potential biomarkers of MDD. These findings support the implication of oxidative stress and inflammatory processes in patients with MDD, and indicate that the deteriorated ROS-antioxidant balance can be regulated via NOX1 in patients with depression.

Gene-Environment Interactions in Repeat Expansion Diseases: Mechanisms of Environmentally Induced Repeat Instability

Short tandem repeats (STRs) are units of 1-6 base pairs that occur in tandem repetition to form a repeat tract. STRs exhibit repeat instability, which generates expansions or contractions of the repeat tract. Over 50 diseases, primarily affecting the central nervous system and muscles, are characterized by repeat instability. Longer repeat tracts are typically associated with earlier age of onset and increased disease severity. Environmental exposures are suspected to play a role in the pathogenesis of repeat expansion diseases. Here, we review the current knowledge of mechanisms of environmentally induced repeat instability in repeat expansion diseases. The current evidence demonstrates that environmental factors modulate repeat instability via DNA damage and induction of DNA repair pathways, with distinct mechanisms for repeat expansion and contraction. Of particular note, oxidative stress is a key mediator of environmentally induced repeat instability. The preliminary evidence suggests epigenetic modifications as potential mediators of environmentally induced repeat instability. Future research incorporating an array of environmental exposures, new human cohorts, and improved model systems, with a continued focus on cell-types, tissues, and critical windows, will aid in identifying mechanisms of environmentally induced repeat instability. Identifying environmental modulators of repeat instability and their mechanisms of action will inform preventions, therapies, and public health measures.

Mesoporous silica nanoparticles: Their potential as drug delivery carriers and nanoscavengers in Alzheimer's and Parkinson's diseases

Worldwide, populations face significant burdens from neurodegenerative disorders (NDDs), especially Alzheimer's and Parkinson's diseases. Although there are many proposed etiologies for neurodegenerative disorders, including genetic and environmental factors, the exact pathogenesis for these disorders is not fully understood. Most patients with NDDs are given lifelong treatment to improve their quality of life. There are myriad treatments for NDDs; however, these agents are limited by their side effects and difficulty in passing the blood-brain barrier (BBB). Furthermore, the central nervous system (CNS) active pharmaceuticals could offer symptomatic relief for the patient's condition without providing a complete cure or prevention by targeting the disease's cause. Recently, Mesoporous silica nanoparticles (MSNs) have gained interest in treating NDDs since their physicochemical properties and inherent ability to pass BBB make them possible drug carriers for several drugs for NDDs treatment. This paper provides insight into the pathogenesis and treatment of NDDs, along with the recent advances in applying MSNs as fibril scavengers. Moreover, the application of MSNs-based formulations in enhancing or sustaining drug release rate, and brain targeting via their responsive release properties, besides the neurotoxicity of MSNs, have been reviewed.

SERS "hot spot" enhance-array assay for misfolded SOD1 correlated with white matter lesions and aging

Misfolding of superoxide dismutase-1 (SOD1) has been correlated with many neurodegenerative diseases, such as Amyotrophic lateral sclerosis's and Alzheimer's among others. However, it is unclear whether misfolded SOD1 plays a role in another neurodegenerative disease of white matter lesions (WMLs). In this study, a sensitive and specific method based on SERS technique was proposed for quantitative detection of misfolded SOD1 content in WMLs. To fabricate the double antibodysandwich substrates for SERS detection, gold nanostars modified with capture antibody were immobilized on glass substrates to prepare active SERS substrates, and then SERS probes conjugated with a Raman reporter and a specific target antibody were coupled with active SERS substrates. This SERS substrates had been employed for quantitative detection of misfolded SOD1 levels in WMLs and exhibited excellent stability, reliability, and accuracy. Moreover, experimental results indicated that the level of misfolded SOD1 increased with the increase in age and the degree of WMLs. Hence, misfolded SOD1 may be a potential blood marker for WMLs and aging. Meanwhile, SERS-based gold nanostars have great clinical application potential in the screening, diagnosis and treatment of WMLs.

Neurological susceptibility to environmental exposures: pathophysiological mechanisms in neurodegeneration and multiple chemical sensitivity

The World Health Organization lists air pollution as one of the top five risks for developing chronic non-communicable disease, joining tobacco use, harmful use of alcohol, unhealthy diets and physical inactivity. This review focuses on how host defense mechanisms against adverse airborne exposures relate to the probable interacting and overlapping pathophysiological features of neurodegeneration and multiple chemical sensitivity. Significant long-term airborne exposures can contribute to oxidative stress, systemic inflammation, transient receptor subfamily vanilloid 1 (TRPV1) and subfamily ankyrin 1 (TRPA1) upregulation and sensitization, with impacts on olfactory and trigeminal nerve function, and eventual loss of brain mass. The potential for neurologic dysfunction, including decreased cognition, chronic pain and central sensitization related to airborne contaminants, can be magnified by genetic polymorphisms that result in less effective detoxification. Onset of neurodegenerative disorders is subtle, with early loss of brain mass and loss of sense of smell. Onset of MCS may be gradual following long-term low dose airborne exposures, or acute following a recognizable exposure. Upregulation of chemosensitive TRPV1 and TRPA1 polymodal receptors has been observed in patients with neurodegeneration, and chemically sensitive individuals with asthma, migraine and MCS. In people with chemical sensitivity, these receptors are also sensitized, which is defined as a reduction in the threshold and an increase in the magnitude of a response to noxious stimulation. There is likely damage to the olfactory system in neurodegeneration and trigeminal nerve hypersensitivity in MCS, with different effects on olfactory processing. The associations of low vitamin D levels and protein kinase activity seen in neurodegeneration have not been studied in MCS. Table 2 presents a summary of neurodegeneration and MCS, comparing 16 distinctive genetic, pathophysiological and clinical features associated with air pollution exposures. There is significant overlap, suggesting potential comorbidity. Canadian Health Measures Survey data indicates an overlap between neurodegeneration and MCS (p < 0.05) that suggests comorbidity, but the extent of increased susceptibility to the other condition is not established. Nevertheless, the pathways to the development of these conditions likely involve TRPV1 and TRPA1 receptors, and so it is hypothesized that manifestation of neurodegeneration and/or MCS and possibly why there is divergence may be influenced by polymorphisms of these receptors, among other factors.

Open Questions on the Electromagnetic Field Contribution to the Risk of Neurodegenerative Diseases

This work presents the current state of knowledge about the possible contributory influence of the electromagnetic field on the occurrence of neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease, amyotrophic lateral sclerosis, and multiple sclerosis. Up-to-date literature indicates both favourable and adverse effects of electromagnetic exposure on human health, making it difficult to come to valid and unambiguous conclusions. The epidemiological data analysis from the World Health Organization statistics shows a substantial rise in neurological mortality compared with rises in total populations in developed countries over a mere 15-year period. The largest of the analysed countries produced odds ratios of >100%. The contribution of electromagnetic exposure to the incidence of neurodegenerative diseases is still undoubtedly open to discussion, and it requires further in-depth research to assess the action mechanism of electromagnetic fields in neurodegenerative diseases. The limitations of research published hitherto and the problem of drawing unequivocal conclusions are also in focus.

In vitro and in silico assessment of cytotoxicity and chromosome instability induced by saxitoxin in human derived neural cell line

In freshwater, saxitoxins (STX) are produced by different cyanobacteria genera, including Raphidiopsis. Data regarding cytogenotoxicity effects of STX on human cells are scarse, this merit further studies of its toxicology. This study assessed the cytotoxicity and the chromosome instability of STX on SHSY-5Y human cell line. The CBMN assay allows the detection of chromosome breaks and abnormal chromosomal segregation. Additionally, in silico systems biology approach, used to search for known and predicted interaction networks, was applied to study the interactions between STX and SHSY-5Y cellular components. The results of the CBMN assay demonstrated that STX concentrations of 2.5 - 10 µg/L induced cytostasis and chromosome instability in a dose-response relationship. Apoptosis was detected after exposure of SHSY-5Y cultured cells to STX concentration of 10 µg/L. The results of the systems biology analysis revealed the interaction of STX with proteins related with acetylcoline pathway, cell cycle regulation and apoptosis. Furthermore, combining the in vitro and in silico approachs, it was possible to suggest a mechanism of action of STX in SHSY-5Y cells. Overall, the data demonstrated the cytotoxicity and mutagenicity of environmentally relevant concentrations of STX. These results should be considered when setting up guidelines for monitoring STX in water supply.

Gene-environment interactions in Alzheimer disease: the emerging role of epigenetics

With the exception of a few monogenic forms, Alzheimer disease (AD) has a complex aetiology that is likely to involve multiple susceptibility genes and environmental factors. The role of environmental factors is difficult to determine and, until a few years ago, the molecular mechanisms underlying gene-environment (G × E) interactions in AD were largely unknown. Here, we review evidence that has emerged over the past two decades to explain how environmental factors, such as diet, lifestyle, alcohol, smoking and pollutants, might interact with the human genome. In particular, we discuss how various environmental AD risk factors can induce epigenetic modifications of key AD-related genes and pathways and consider how epigenetic mechanisms could contribute to the effects of oxidative stress on AD onset. Studies on early-life exposures are helping to uncover critical time windows of sensitivity to epigenetic influences from environmental factors, thereby laying the foundations for future primary preventative approaches. We conclude that epigenetic modifications need to be considered when assessing G × E interactions in AD.

Relationship between Selected Micronutrient Concentrations, Total Antioxidant Status, Pain Severity, and the Image of 1H MR Spectroscopy in Degenerative Spine Disease: A Case-Control Study

Osteoarthritis of the spine is a common disease and constitutes a significant problem in highly developed countries. Due to the aging of the population, the number of patients with advanced degenerative changes continues to grow. Trace elements and antioxidant status may play an active role in the pathogenesis of osteoarthritis of the spine. The aim of this study was to assess the relationship between total antioxidant status (TAS), the concentration of selected elements (Zn, Cu, Se, Mn) in the serum, nutritional and environmental factors, the severity of pain, and images of degenerative changes in the spine demonstrated in proton magnetic resonance spectroscopy (¹H MRS). The study included 90 patients with degenerative spine disease and 40 healthy people. Serum Zn, Cu, Se, and Mn concentrations were determined by atomic absorption spectrometry. The Cu/Zn molar ratio was calculated. TAS was determined spectrophotometrically using a ready-made Randox kit. The severity of spine pain was assessed using the visual analogue scale VAS. In the ¹H MRS study, the fat/water ratio was determined in L1 and L5 vertebral bodies and in the L4/5 intervertebral disc. In patients with osteoarthritis of the spine, there was a reduced concentration of Zn and Cu in the serum (0.77 ± 0.22 mg/L, 1.1 ± 0.35 mg/L) compared to the control group (0.83 ± 0.13 mg/L, 1.25 ± 0.41 mg/L, respectively). In the study group, we also observed a significantly lower Cu concentration in smokers (1.07 ± 0.35 mg/L) compared to non-smokers (1.17 ± 0.34 mg/L). A relationship between the female sex and a decreased concentration of TAS in the serum, both in people with degenerative spine disease and in healthy people, has been demonstrated. In patients with serum TAS levels below the reference values, the fat/water ratio was higher in the L5 spine shaft, while in those with elevated Mn levels, the value was higher in the L4/L5 intervertebral disc, which indicates a greater degree of degeneration in both cases. Patients with normal serum Cu concentration experienced lower pain intensity assessed in the VAS scale. The study showed some abnormalities in serum trace element levels and TAS in patients with osteoarthritis of the spine.

Impact of Environmental Risk Factors on Mitochondrial Dysfunction, Neuroinflammation, Protein Misfolding, and Oxidative Stress in the Etiopathogenesis of Parkinson's Disease

As a prevalent progressive neurodegenerative disorder, Parkinson's disease (PD) is characterized by the neuropathological hallmark of the loss of nigrostriatal dopaminergic (DAergic) innervation and the appearance of Lewy bodies with aggregated α-synuclein. Although several familial forms of PD have been reported to be associated with several gene variants, most cases in nature are sporadic, triggered by a complex interplay of genetic and environmental risk factors. Numerous epidemiological studies during the past two decades have shown positive associations between PD and several environmental factors, including exposure to neurotoxic pesticides/herbicides and heavy metals as well as traumatic brain injury. Other environmental factors that have been implicated as potential risk factors for PD include industrial chemicals, wood pulp mills, farming, well-water consumption, and rural residence. In this review, we summarize the environmental toxicology of PD with the focus on the elaboration of chemical toxicity and the underlying pathogenic mechanisms associated with exposure to several neurotoxic chemicals, specifically 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), rotenone, paraquat (PQ), dichloro-diphenyl-trichloroethane (DDT), dieldrin, manganese (Mn), and vanadium (V). Our overview of the current findings from cellular, animal, and human studies of PD provides information for possible intervention strategies aimed at halting the initiation and exacerbation of environmentally linked PD.

Air Pollution and Hospital Admission for Epilepsy in Kerman, Iran

Background: This study aimed to investigate the relation between air pollution and epilepsy admissions in Kerman, Iran. Methods: In this ecological study, the concentrations of ambient air pollutants and meteorological data were obtained from Kerman Environmental Protection Agency and Kerman Meteorology Organization, respectively. Additionally, epilepsy admission data were obtained from Kerman’s Shafa hospital epilepsy registry. Generalized additive models with lags up to 7 days were used to estimate rate ratios (RRs). Results: Within 2008 to 2020, 894 epilepsy admissions occurred in Kerman, 498 cases (55.7%) of whom were male. The strongest relations of epilepsy admission were observed in the over 59-year group for carbon monoxide (CO) in lag 0 (RR = 2.1455, 95% CI: 1.5823 - 2.9091), nitrogen dioxide (NO2) in lag 0 (RR = 1.0409, 95% CI: 1.0282 - 1.0537), and particulate matter under 2.5 microns (PM2.5) in lag 5 (RR = 1.0157, 95% CI: 1.0062 - 1.0252). There were also significant associations for particulate matter under 10 microns (PM10) in the under 18-year group in lag 2 (RR = 1.0064, 95% CI: 1.0029 - 1.0098), ozone in lag 0 (RR = 0.9671, 95% CI: 0.9581 - 0.9761), and sulfur dioxide in lag 5 (RR = 0.9937, 95% CI: 0.9891 - 0.9983). Conclusions: Exposure to CO, NO2, PM2.5, or PM10 air pollutants might be a risk factor for epilepsy admissions in Kerman. Epilepsy patients should better stay away from exposure to polluted air. Staying at home on polluted days or residing in areas with less air pollution might be an option.

Role of the Gut–Brain Axis, Gut Microbial Composition, Diet, and Probiotic Intervention in Parkinson’s Disease

Parkinson’s disease (PD) is the second-most prevalent neurodegenerative or neuropsychiatric disease, affecting 1% of seniors worldwide. The gut microbiota (GM) is one of the key access controls for most diseases and disorders. Disturbance in the GM creates an imbalance in the function and circulation of metabolites, resulting in unhealthy conditions. Any dysbiosis could affect the function of the gut, consequently disturbing the equilibrium in the intestine, and provoking pro-inflammatory conditions in the gut lumen, which send signals to the central nervous system (CNS) through the vagus enteric nervous system, possibly disturbing the blood–brain barrier. The neuroinflammatory conditions in the brain cause accumulation of α-syn, and progressively develop PD. An important aspect of understanding and treating the disease is access to broad knowledge about the influence of dietary supplements on GM. Probiotics are live microorganisms which, when administered in adequate amounts, confer a health benefit on the host. Probiotic supplementation improves the function of the CNS, and improves the motor and non-motor symptoms of PD. Probiotic supplementation could be an adjuvant therapeutic method to manage PD. This review summarizes the role of GM in health, the GM–brain axis, the pathogenesis of PD, the role of GM and diet in PD, and the influence of probiotic supplementation on PD. The study encourages further detailed clinical trials in PD patients with probiotics, which aids in determining the involvement of GM, intestinal mediators, and neurological mediators in the treatment or management of PD.

Succinate Dehydrogenase, Succinate, and Superoxides: A Genetic, Epigenetic, Metabolic, Environmental Explosive Crossroad

Research focused on succinate dehydrogenase (SDH) and its substrate, succinate, culminated in the 1950s accompanying the rapid development of research dedicated to bioenergetics and intermediary metabolism. This allowed researchers to uncover the implication of SDH in both the mitochondrial respiratory chain and the Krebs cycle. Nowadays, this theme is experiencing a real revival following the discovery of the role of SDH and succinate in a subset of tumors and cancers in humans. The aim of this review is to enlighten the many questions yet unanswered, ranging from fundamental to clinically oriented aspects, up to the danger of the current use of SDH as a target for a subclass of pesticides.

PS-NPs Induced Neurotoxic Effects in SHSY-5Y Cells via Autophagy Activation and Mitochondrial Dysfunction

Polystyrene nanoparticles (PS-NPs) are organic pollutants that are widely detected in the environment and organisms, posing potential threats to both ecosystems and human health. PS-NPs have been proven to penetrate the blood–brain barrier and increase the incidence of neurodegenerative diseases. However, information relating to the pathogenic molecular mechanism is still unclear. This study investigated the neurotoxicity and regulatory mechanisms of PS-NPs in human neuroblastoma SHSY-5Y cells. The results show that PS-NPs caused obvious mitochondrial damages, as evidenced by inhibited cell proliferation, increased lactate dehydrogenase release, stimulated oxidative stress responses, elevated Ca2+ level and apoptosis, and reduced mitochondrial membrane potential and adenosine triphosphate levels. The increased release of cytochrome c and the overexpression of apoptosis-related proteins apoptotic protease activating factor-1 (Apaf-1), cysteinyl aspartate specific proteinase-3 (caspase-3), and caspase-9 indicate the activation of the mitochondrial apoptosis pathway. In addition, the upregulation of autophagy markers light chain 3-II (LC3-II), Beclin-1, and autophagy-related protein (Atg) 5/12/16L suggests that PS-NPs could promote autophagy in SHSY-5Y cells. The RNA interference of Beclin-1 confirms the regulatory role of autophagy in PS-NP-induced neurotoxicity. The administration of antioxidant N-acetylcysteine (NAC) significantly attenuated the cytotoxicity and autophagy activation induced by PS-NP exposure. Generally, PS-NPs could induce neurotoxicity in SHSY-5Y cells via autophagy activation and mitochondria dysfunction, which was modulated by mitochondrial oxidative stress. Mitochondrial damages caused by oxidative stress could potentially be involved in the pathological mechanisms for PS-NP-induced neurodegenerative diseases.

Residential green space and air pollution are associated with brain activation in a social-stress paradigm

We examined the influence of three major environmental variables at the place of residence as potential moderating variables for neurofunctional activation during a social-stress paradigm. Data from functional magnetic resonance imaging of 42 male participants were linked to publicly accessible governmental databases providing information on amount of green space, air pollution, and noise pollution. We hypothesized that stress-related brain activation in regions important for emotion regulation were associated positively with green space and associated negatively with air pollution and noise pollution. A higher percentage of green space was associated with stronger parietal and insular activation during stress compared with that in the control condition. More air pollution was associated with weaker activation in the same (but also extended) brain regions. These findings may serve as an important reference for future studies in the emerging field of “neuro-urbanism” and emphasize the importance of environmental factors in urban planning.

Role of Environmental Toxicants on Neurodegenerative Disorders

Neurodegeneration leads to the loss of structural and functioning components of neurons over time. Various studies have related neurodegeneration to a number of degenerative disorders. Neurological repercussions of neurodegeneration can have severe impacts on the physical and mental health of patients. In the recent past, various neurodegenerative ailments such as Alzheimer’s and Parkinson’s illnesses have received global consideration owing to their global occurrence. Environmental attributes have been regarded as the main contributors to neural dysfunction-related disorders. The majority of neurological diseases are mainly related to prenatal and postnatal exposure to industrially produced environmental toxins. Some neurotoxic metals, like lead (Pb), aluminium (Al), Mercury (Hg), manganese (Mn), cadmium (Cd), and arsenic (As), and also pesticides and metal-based nanoparticles, have been implicated in Parkinson’s and Alzheimer’s disease. The contaminants are known for their ability to produce senile or amyloid plaques and neurofibrillary tangles (NFTs), which are the key features of these neurological dysfunctions. Besides, solvent exposure is also a significant contributor to neurological diseases. This study recapitulates the role of environmental neurotoxins on neurodegeneration with special emphasis on major neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease.

Antioxidant Peptides From Protein Hydrolysate of Marine Red Algae Eucheuma cottonii: Preparation, Identification, and Cytoprotective Mechanisms on H2O2 Oxidative Damaged HUVECs

To screen, prepare, identify, and evaluate the activities of natural antioxidants for treating chronic diseases caused by oxidative stress. Two algal proteins, namely ZD10 and ZD60, precipitated with 10 and 60% (NH₄)₂SO₄ were extracted from red algae Eucheuma cottonii (E. cottonii) and hydrolyzed using five proteolytic enzymes. The results showed that ZD60 played the most significant role in the enhancement of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH⋅) scavenging activity (25.91 ± 0.24%) among all protein hydrolysates. Subsequently, six antioxidant peptides (EP1-EP6) were isolated from the papain hydrolysate of ZD60 by ultrafiltration and chromatography methods. Their amino acid sequences were identified as Thr-Ala (EP1), Met-Asn (EP2), Tyr-Ser-Lys-Thr (EP3), Tyr-Ala-Val-Thr (EP4), Tyr-Leu-Leu (EP5), and Phe-Tyr-Lys-Ala (EP6) with molecular weights of 190.21, 263.33, 497.55, 452.51, 407.51, and 527.62 Da, respectively. Of which, EP3, EP4, EP5, and EP6 showed strong scavenging activities on DPPH⋅, hydroxyl radical (HO⋅), and superoxide anion radical (O- 2⋅). Moreover, EP4 and EP5 could significantly protect human umbilical vein endothelial cells (HUVECs) from H₂O₂-induced oxidative damage by increasing the levels of antioxidant enzyme systems including superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) to reduce the levels of reactive oxygen species (ROS) (60.51 and 51.74% of model group) and malondialdehyde (MDA) (75.36 and 64.45% of model group). In addition, EP4 and EP5 could effectively inhibit H₂O₂-induced apoptosis by preventing HUVECs from early apoptosis to late apoptosis. These results indicated that the antioxidant peptides derived from E. cottonii, especially EP4 and EP5, could serve as the natural antioxidants applied in pharmaceutical products to treat chronic cardiovascular diseases caused by oxidative damage, such as coronary heart disease, atherosclerosis, etc.

Associations between household solid fuel use and hearing loss in a Chinese population: A population-based prospective cohort study

Hearing loss, a common chronic condition, severely affects the quality of human life. However, the longitudinal relationships between household solid fuel use and hearing loss are unclear. To explore the associations between household solid fuel use and hearing loss in a Chinese population. There were 8835 participants enrolled in this prospective cohort study. Hearing function was assessed by asking the following self-reported question. Cox proportional hazards regression models were used to examine the relationships between baseline household solid fuel use and hearing loss incidence. After 6 (range, 2-7) years of follow-up, 1654 (18.72%) of 8835 participants developed hearing loss. This study demonstrated that increasing baseline solid fuel exposure was associated with a higher rate of poor hearing function (P for trend < 0.01). Compared with the clean fuel group (both cooking and heating), the hazard ratios (HR) (95% confidence intervals) of poor hearing function for the solid fuel group (cooking or heating) and both solid fuel groups (both cooking and heating) were 1.17 (1.01, 1.37) and 1.26 (1.09, 1.45) after adjustments, respectively. In subgroup analysis of household energy sources, the use of solid fuels for both heating (HR, 1.21; 1.07, 1.37) and cooking (HR, 1.12; 1.01, 1.26) was related to a higher incidence of poor hearing function. In subgroup analysis of place of residence, more solid fuel use was associated with a higher rate of poor hearing function in urban communities (HR, 1.39; 1.12, 1.74) but not in rural villages (HR, 1.18; 0.97, 1.45). Moreover, compared with the population that used solid fuel for cooking at both baseline and follow-up, those who switched from solid to clean fuel had a lower risk of developing poor hearing function (HR, 0.54, 0.46-0.63). This study demonstrates that household solid fuel use is closely associated with poor hearing function. Programs that educate individuals on the effects of household fuel use on hearing function should be established, especially in urban communities.

Curcumin protects against manganese-induced neurotoxicity in rat by regulating oxidative stress-related gene expression via H3K27 acetylation

Long-term manganese exposure causes a neurodegenerative disorder referred to as manganese poisoning, but the mechanism remains unclear and no specific treatment is available. Oxidative stress is widely recognised as one of the main causes of manganese-induced neurotoxicity. In recent years, the role of histone acetylation in neurodegenerative diseases has been widely concerned. curcumin is a natural polyphenol compound extracted from the rhizome of turmeric and exhibits both antioxidant and neuroprotective properties. Therefore, we aimed to investigate whether and how curcumin protects against manganese-induced neurotoxicity from the perspective of histone acetylation, based on the reversibility of histone acetylation modification. In this study, rats were treated with or without curcumin and subjected to long-term manganese exposure. Results that treatment of manganese decreased the protein expression of H3K18 acetylation and H3K27 acetylation at the promoters of oxidative stress-related genes and inhibited the expression of these genes. Nevertheless, curcumin increased the H3K27 acetylation level at the manganese superoxide dismutase (SOD2) gene promoter and promoted the expression of SOD2 gene. Oxidative damage in the rat striatum as well as learning and memory dysfunction were ameliorated after curcumin treatment. Taken together, our results suggest that the regulation of oxidative stress by histone acetylation may be a key mechanism of manganese-induced neurotoxicity. In addition, curcumin ameliorates Mn-induced neurotoxicity may be due to alleviation of oxidative damage mediated by increased activation of H3K27 acetylation at the SOD2 gene promoter.

Role of brain extracellular vesicles in air pollution-related cognitive impairment and neurodegeneration

A relationship between environmental exposure to air pollution and cognitive impairment and neurological disorders has been described. Previous literature has focused on the direct effects of the air pollution components on neuronal and glial cells, as well as on involvement of oxidative stress and neuroinflammation on microglia and astrocyte reactivity. However, other mechanisms involved in the air pollution effects on central nervous system (CNS) toxicity can be playing critical roles. Increasingly, extracellular vesicle's (EVs) mediated intercellular communication is being recognized as impacting the development of cognitive impairment and neurological disorders like Alzheimer's disease and others. Here we describe the available evidence about toxic air pollutants and its components on brain, an involvement of brain cells specific and EVs types (based in the origin or in the size of EVs) in the initiation, exacerbation, and propagation of the neurotoxic effects (inflammation, neurodegeneration, and accumulation of neurotoxic proteins) induced by air pollution in the CNS. Additionally, we discuss the identification and isolation of neural-derived EVs from human plasma, the most common markers for neural-derived EVs, and their potential for use as diagnostic or therapeutic molecules for air pollution-related cognitive impairment and neurodegeneration.

Early life environmental factors associated with autism spectrum disorder symptoms in children at age 2 years: A birth cohort study

LAY ABSTRACT

Mounting evidence indicates the contribution of early life environmental factors in autism spectrum disorder. We aim to report the prospective associations between early life environmental factors and autism spectrum disorder symptoms in children at the age of 2 years in a population-derived birth cohort, the Barwon Infant Study. Autism spectrum disorder symptoms at the age of 2 years strongly predicted autism spectrum disorder diagnosis by the age of 4 years (area under curve = 0.93; 95% CI (0.82, 1.00)). After adjusting for child's sex and age at the time of behavioural assessment, markers of socioeconomic disadvantage, such as lower household income and lone parental status; maternal health factors, including younger maternal age, maternal pre-pregnancy body mass index, higher gestational weight gain and prenatal maternal stress; maternal lifestyle factors, such as prenatal alcohol and environmental air pollutant exposures, including particulate matter < 2.5 μm at birth, child secondhand tobacco smoke at 12 months, dampness/mould and home heating with oil, kerosene or diesel heaters at 2 years postnatal. Lower socioeconomic indexes for area, later birth order, higher maternal prenatal depression and maternal smoking frequency had a dose-response relationship with autism spectrum disorder symptoms. Future studies on environmental factors and autism spectrum disorder should consider the reasons for the socioeconomic disparity and the combined impact of multiple environmental factors through common mechanistic pathways.

Sulfur dioxide derivatives attenuates consolidation of contextual fear memory in mice

Post-traumatic stress disorder (PTSD) is characterized by an enhancement of traumatic memory. Intervention strategies based on the different stages of memory have been shown to be effective in the prevention and control of PTSD. The endogenous gaseous molecule, sulfur dioxide (SO₂), has been reported to significantly exert neuromodulatory effects; however, its regulation of learning and memory remains unestablished. This study aimed to investigate the effects of exogenous SO₂ derivatives administration on the formation, consolidation, reconsolidation, retention, and expression of contextual fear memory. Behavioral results showed that both intraperitoneal injection (50 mg/kg, ip) and hippocampal infusion (5 μg/side) of SO₂ derivatives (a mixture of sodium sulfite and sodium bisulfite, Na₂SO₃/NaHSO₃, 3:1 M/M) significantly impaired consolidation but had no effect on reconsolidation and retention of contextual fear memory. These findings suggest that the attenuating effects of SO₂ on the consolidation of fear memory involves, at least partially, the region of the hippocampus. The findings of this study provide direct evidence for the development of new strategies for PTSD prevention and treatment involving the use of gaseous SO₂.

Alzheimer's Disease: Pathogenesis and Therapeutic Interventions

BACKGROUND

Alzheimer's Disease (AD) is the most common cause of dementia. Genetics, excessive exposure to environmental pollutants, as well as unhealthy lifestyle practices are often linked to the development of AD. No therapeutic approach has achieved complete success in treating AD; however, early detection and management with appropriate drugs are key to improving prognosis.

INTERVENTIONS

The pathogenesis of AD was extensively discussed in order to understand the reasons for the interventions suggested. The interventions reviewed include the use of different therapeutic agents and approaches, gene therapy, adherence to healthy dietary plans (Mediterranean diet, Okinawan diet and MIND diet), as well as the use of medicinal plants. The potential of nanotechnology as a multidisciplinary and interdisciplinary approach in the design of nano-formulations of AD drugs and the use of Superparamagnetic Iron Oxide Nanoparticles (SPIONs) as theranostic tools for early detection of Alzheimer's disease were also discussed.

Diketopyrrolopyrrole-based fluorescent probe for endogenous bisulfite detection and bisulfite triggered phototoxicity specific in liver cancer cells

As the main existing form of SO₂ derivatives, bisulfite showed closely relationship to many diseases. In this work, a new fluorescent probe (SDPP-DM) based on thienyl-substituted diketopyrrolopyrrole (SDPP) was designed and synthesized for the detection of endogenous bisulfite. The probe displayed obvious color changes from green to pink towards bisulfite due to the reduced conjugated length caused by the addition to the α,β-unsaturated double bond of its structure, and the change of the fluorescence intensity of SDPP-DM (I/I₀) was about 16 folds. In addition, SDPP-DM was prepared a test strip for bisulfite identified by naked eye through color and fluorescence changes. Besides, SDPP-DM was successfully applied to imaging and discriminating different endogenous bisulfite levels in normal and cancer cells of liver. More importantly, the ROS generation and cell viability tests showed the phototoxicity of SDPP-DM triggered by bisulfite, indicating the specific phototoxicity of SDPP-DM towards liver cancer cells than normal liver cells.

Polyphenols and Stem Cells for Neuroregeneration in Parkinson's Disease and Amyotrophic Lateral Sclerosis

Parkinson's disease (PD) and Amyotrophic lateral sclerosis (ALS) are neurological disorders, pathologically characterized by chronic degeneration of dopaminergic neurons and motor neurons respectively. There is still no cure or effective treatment against the disease progression and most of the treatments are symptomatic. The present review offers an overview of the different factors involved in the pathogenesis of these diseases. Subsequently, we focused on the recent advanced studies of dietary polyphenols and stem cell therapies, which have made it possible to slow down the progression of neurodegeneration. To date, stem cells and different polyphenols have been used for the directional induction of neural stem cells into dopaminergic neurons and motor neurons. We have also discussed their involvement in the modulation of different signal transduction pathways and growth factor levels in various in vivo and in vitro studies. Likewise stem cells, polyphenols also exhibit the potential of neuroprotection by their anti-apoptotic, anti-inflammatory, anti-oxidant properties regulating the growth factors levels and molecular signaling events. Overall this review provides a detailed insight into recent strategies that promise the use of polyphenol with stem cell therapy for the possible treatment of PD and ALS.

Oxidative Stress and Cognitive Decline: The Neuroprotective Role of Natural Antioxidants

Free- radicals (Oxygen and Nitrogen species) are formed in mitochondria during the oxidative phosphorylation. Their high reactivity, due to not-engaged electrons, leads to an increase of the oxidative stress. This condition affects above all the brain, that usually needs a large oxygen amount and in which there is the major possibility to accumulate "Reacting Species." Antioxidant molecules are fundamental in limiting free-radical damage, in particular in the central nervous system: the oxidative stress, in fact, seems to worsen the course of neurodegenerative diseases. The aim of this review is to sum up natural antioxidant molecules with the greatest neuroprotective properties against free radical genesis, understanding their relationship with the Central Nervous System.

Long-term exposure to air pollution and the risk of developing sudden sensorineural hearing loss

Background

The association between exposure to air pollution and sudden sensorineural hearing loss (SSNHL) has not been extensively discussed in the literature. Therefore, we conducted this nationwide study to evaluate the risk of SSNHL in Taiwanese residents with exposure to air pollution.

Methods

We enrolled subjects aged older than 20 years with no history of SSNHL from 1998 to 2010, and followed up until developing SSNHL, withdrawn from the National Health Insurance program, and the end of the database (2011/12/31). The air quality data are managed by Taiwan Environmental Protection Administration. The annual concentrations of PM_2.5, SO₂, CO, NO, and NO₂ from 1998 to 2010 were classified into the three levels according to tertiles. We calculated the annual average of pollutants from baseline until the end of the study, and classified into tertiles. The adjusted hazard ratio (aHR) was estimated by using the multivariate Cox proportional hazard model.

Results

When considered continuous air pollutants concentration, subjects who exposed with higher concentration of CO (aHR = 2.16, 95% CI 1.50–3.11), NO (aHR = 1.02, 95% CI 1.01–1.03), and NO₂ (aHR = 1.02, 95% CI 1.01–1.04) developing significant higher risk of SSNHL. When classified air pollutants concentration into low, moderate and high level by tertiles, and selected low level as reference, patients exposed with moderate (aHR = 1.56, 95% CI 1.20–2.04) or high level (aHR = 1.33, 95% CI 1.01–1.75) of PM_2.5 showed significant higher risk of developing SSNHL.

Conclusion

This study indicated an increased risk of SSNHL in residents with long-term exposure to air pollution. Nevertheless, further experimental, and clinical studies are needed to validate the study findings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03095-8.

Histone deacetylase HDA-4-mediated epigenetic regulation in space-flown C. elegans

Epigenetic changes during long-term spaceflight are beginning to be studied by NASA's twin astronauts and other model organisms. Here, we evaluate the epigenetic regulation of gene expression in space-flown C. elegans by comparing wild type and histone deacetylase (hda)-4 mutants. Expression levels of 39 genes were consistently upregulated in all four generations of adult hda-4 mutants grown under microgravity compared with artificial Earth-like gravity (1G). In contrast, in the wild type, microgravity-induced upregulation of these genes occurred a little. Among these genes, 11 contain the domain of unknown function 19 (DUF-19) and are located in a cluster on chromosome V. When compared with the 1G condition, histone H3 trimethylation at lysine 27 (H3K27me3) increased under microgravity in the DUF-19 containing genes T20D4.12 to 4.10 locus in wild-type adults. On the other hand, this increase was also observed in the hda-4 mutant, but the level was significantly reduced. The body length of wild-type adults decreased slightly but significantly when grown under microgravity. This decrease was even more pronounced with the hda-4 mutant. In ground-based experiments, one of the T20D4.11 overexpressing strains significantly reduced body length and also caused larval growth retardation and arrest. These results indicate that under microgravity, C. elegans activates histone deacetylase HDA-4 to suppress overregulation of several genes, including the DUF-19 family. In other words, the expression of certain genes, including negative regulators of growth and development, is epigenetically fine-tuned to adapt to the space microgravity.

Polychlorinated biphenyls induce oxidative stress and metabolic responses in astrocytes

Exposure to environmental toxicants is prevalent, hazardous and linked to varied detrimental health outcomes and disease. Polychlorinated biphenyls (PCBs), a class of hazardous organic chlorines once widely used for industrial purposes, are associated with neurodegenerative disease and oxidative stress in both in vitro and in vivo models. Here, we investigated the impact of Aroclor 1254, a commercially available PCB mixture, on primary murine astrocytes to determine the response to this once ubiquitously used toxicant on the most numerous cells of the central nervous system (CNS). Astrocytes are a critical component of homeostasis throughout the CNS, including at the blood-brain barrier, where they serve as the primary defense against xenobiotics entering the CNS, and at the synapse, where they are closely coupled to neurons through several metabolic pathways. We hypothesized that PCBs cause astrocytic oxidative stress and related dysfunction including altered metabolism. We exposed primary murine cortical astrocytes to PCBs and report an increased expression of antioxidant genes (Prdx1, Gsta2, Gfap, Amigo2) in response to oxidative stress. Our data show increased ATP production and spare respiratory capacity in astrocytes exposed to 10 μM (∼ 3 ppm) PCBs. This dose also causes an increase in glucose uptake that is not seen at a higher dose (50 μM) suggesting that, at a lower dose, astrocytes are able to engage compensatory mechanisms to promote survival. Together, these data suggest that exposure to PCBs impact astrocytic metabolism, which is important to consider both in the context of human health and disease and in in vitro and in vivo disease models.

Chromophore of an Enhanced Green Fluorescent Protein Can Play a Photoprotective Role Due to Photobleaching

Under stress conditions, elevated levels of cellular reactive oxygen species (ROS) may impair crucial cellular structures. To counteract the resulting oxidative damage, living cells are equipped with several defense mechanisms, including photoprotective functions of specific proteins. Here, we discuss the plausible ROS scavenging mechanisms by the enhanced green fluorescent protein, EGFP. To check if this protein could fulfill a photoprotective function, we employed electron spin resonance (ESR) in combination with spin-trapping. Two organic photosensitizers, rose bengal and methylene blue, as well as an inorganic photocatalyst, nano-TiO₂, were used to photogenerate ROS. Spin-traps, TMP-OH and DMPO, and a nitroxide radical, TEMPOL, served as molecular targets for ROS. Our results show that EGFP quenches various forms of ROS, including superoxide radicals and singlet oxygen. Compared to the three proteins PNP, papain, and BSA, EGFP revealed high ROS quenching ability, which suggests its photoprotective role in living systems. Damage to the EGFP chromophore was also observed under strong photo-oxidative conditions. This study contributes to the discussion on the protective function of fluorescent proteins homologous to the green fluorescent protein (GFP). It also draws attention to the possible interactions of GFP-like proteins with ROS in systems where such proteins are used as biological markers.

Maternal fructose consumption downregulates hippocampal catalase expression via DNA methylation in rat offspring

Some studies have demonstrated that excessive fructose consumption negatively impact brain function. Recently, the Developmental Origins of Health and Disease hypothesis - which suggests that maternal nutritional status during gestation and lactation can alter offspring phenotype - has received much attention. In a previous study, we demonstrated that maternal fructose consumption increases levels of lipid peroxides in hippocampi of offspring. The hypothesis in the present study was that maternal fructose intake would affect hippocampal antioxidant enzyme via epigenetic regulation. Upon confirmation of gestation, female rats were assigned to receive either water (control group) or a 20% fructose solution (fructose-fed group). Water or fructose solution were administered to dams from day 1 of gestation to postnatal day 21. Immediately after weaning, hippocampi of offspring were removed for analysis of antioxidant enzyme (Sod1, Sod2, Gpx1, Gpx4, and Cat) messenger RNA transcript levels. Levels of the Cat transcript were significantly lower in the fructose-fed relative to the control group. The Cat protein level was also significantly lower in the fructose-fed relative to the control group as with the messenger RNA transcript levels. Moreover, Cat promoter DNA methylation levels were higher in the fructose-fed group. The present study indicates that maternal fructose consumption may decrease offspring hippocampal Cat transcript levels via altered DNA methylation, which may result in higher levels of oxidative stress due to a decreased ability to neutralize lipid peroxides.

Conjugated linoleic acid protects brain mitochondrial function in acrolein induced male rats

Acrolein (AC) is a toxic substance that can have a neurotoxic effect. It can cause oxidative stress and mitochondrial dysfunction. Conjugated linoleic acid (CLA), a dietary supplement, has many biological functions. Limited information is available about the effect of CLA on AC-induced brain toxicity. Therefore, the present study aims to investigate the effect of CLA on mitochondrial oxidative stress, respiratory enzymes, krebs cycle enzymes and ATP levels in AC treated rat brain. Sprague Dawley male rats were given AC (5 mg/kg i.p.), CLA (200 mg/kg orally) and CLA with AC for six days per week for 30 days. Some oxidative stress parameters and mitochondrial enzymes such as manganese super oxide dismutase, glutathione peroxidase, NADP⁺-dependent isocitrate dehydrogenase (ICDH), alpha-ketoglutarate dehydrogenase (α-KGDH), malate dehydrogenase, reduced glutathione (GSH), lipid peroxidation (LP), protein carbonyl (PC), oxidative phosphorylation (OXPHOS) and tricarboxylic acid cycle (TCA) enzymes, and ATP levels were determined. AC significantly decreased the activities of GSH, antioxidant enzymes, OXPHOS enzymes (complex I and IV), TCA enzymes (ICDH and α-KGDH) and ATP levels. Significant increases were also observed in mitochondrial LP and PC levels in AC group. Co-treatment with AC + CLA improved oxidative stress and mitochondrial dysfunction caused by AC. As a result of our findings, it was observed that CLA was effective in improving oxidative stress and impaired mitochondrial functions in brain tissue by the effect of AC. Considering the association between neurodegenerative diseases and mitochondrial dysfunction, CLA can play a role in the prevention and therapy of neurodegenerative disorders.

Curcumin Decreases Hippocampal Neurodegeneration and Nitro-Oxidative Damage to Plasma Proteins and Lipids Caused by Short-Term Exposure to Ozone

Neurodegeneration is the consequence of harmful events affecting the nervous system that lead to neuronal death. Toxic substances, including air pollutants, are capable of inducing neurodegeneration. Ozone (O₃) is the most oxidative toxic pollutant. O₃ reacts with cellular components and forms reactive oxygen and nitrogen species, triggering nitro-oxidative damage during short-term exposure. Curcumin (CUR) is a natural phenolic molecule bearing well-documented antioxidant and anti-inflammatory biological activities in diverse experimental models. The aim of this work was to evaluate the effect of preventive dietary administration of CUR against hippocampal neurodegeneration and nitro-oxidative damage caused by short-term exposure to O₃. Eighty Wistar male rats were distributed into four experimental groups, twenty rats each: intact control; CUR dietary supplementation without O₃ exposure; exposure to 0.7 ppm of O₃; and exposed to O₃ with CUR dietary supplementation. Five rats from each group were sacrificed at 1, 2, 4, and 8 h of exposure. The CUR dose was 5.6 mg/kg and adjusted according to food consumption. CUR significantly decreased oxidative damage to plasma lipids and proteins, as well as neurodegeneration in CA1 and CA3 hippocampal regions. Concluding, CUR proved effective protection in decreasing neurodegeneration in the hippocampus and prevented systemic oxidative damage.

Aberrant redox biology and epigenetic reprogramming: Co-conspirators across multiple human diseases

An epigenetic landscape encompasses a series of dynamic interconnected mechanisms working together to fashion a diverse set of phenotypes from a singular genotype. The epigenetic plasticity observed in disease and development is facilitated by enzymes that create and remove covalent modifications to DNA and histones. Several important discoveries within the past decade have revealed that epigenetic control mechanisms are subject to redox regulation and mitochondrial-to-nuclear retrograde signaling. This has led to our current understanding that the writers and erasers of the epigenome are influenced by several levels of redox and metabolic control including the bioavailability of oxygen, nutrients, and metabolite co-factors necessary for optimal enzyme activity. Thus, these enzymes perceive a cell's redox state, metabolic status, and environmental signals to influence chromatin structure and accessibility to the transcriptional apparatus. Not only are the activities of epigenetic enzymes affected by cellular redox conditions, but also, in feedback loop fashion, genes encoding antioxidant enzymes as well as prooxidant enzymes can be altered in their expression patterns by epigenetic silencing mechanisms. The altered expression of the anti- and prooxidant genes can then contribute to the onset or progression of disease. Epigenetic regulation of gene expression by the confluence of redox biology and gene-environment interactions is an active area of research and our understanding of these links continues to evolve. Given the emergent importance of crosstalk between redox biology and epigenetic regulatory mechanisms, it is timely that this issue should explore the current state of knowledge on this topic and how changes in metabolism and redox flux can result in tectonic shifts of the epigenetic landscape.

One-carbon epigenetics and redox biology of neurodegeneration

One-carbon metabolism provides the methyl groups for both DNA and histone tail methylation reactions, two of the main epigenetic processes that tightly regulate the chromatin structure and gene expression levels. Several enzymes involved in one-carbon metabolism, as well as several epigenetic enzymes, are regulated by intracellular metabolites and redox cofactors, but their expression levels are in turn regulated by epigenetic modifications, in such a way that metabolism and gene expression reciprocally regulate each other to maintain homeostasis and regulate cell growth, survival, differentiation and response to environmental stimuli. Increasing evidence highlights the contribution of impaired one-carbon metabolism and epigenetic modifications in neurodegeneration. This article provides an overview of DNA and histone tail methylation changes in major neurodegenerative disorders, namely Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis, discussing the contribution of oxidative stress and impaired one-carbon and redox metabolism to their onset and progression.

(-)-Loliolide Isolated from Sargassum horneri Suppressed Oxidative Stress and Inflammation by Activating Nrf2/HO-1 Signaling in IFN-γ/TNF-α-Stimulated HaCaT Keratinocytes

The present study evaluated the effects of (-)-loliolide isolated from Sargassum horneri (S. horneri) against oxidative stress and inflammation, and its biological mechanism in interferon (IFN)-γ/tumor necrosis factor (TNF)-α-stimulated HaCaT keratinocytes. The results showed that (-)-loliolide improved the cell viability by reducing the production of intracellular reactive oxygen species (ROS) in IFN-γ/TNF-α-stimulated HaCaT keratinocytes. In addition, (-)-loliolide effectively decreased the expression of inflammatory cytokines (interleukin (IL)-4 IL-6, IL-13, IFN-γ and TNF-α) and chemokines (CCL11 (Eotaxin), macrophage-derived chemokine (MDC), regulated on activation, normal T cell expressed and secreted (RANTES), and thymus and activation-regulated chemokine (TARC)), by downregulating the expression of epidermal-derived initial cytokines (IL-25, IL-33 and thymic stromal lymphopoietin (TSLP)). Furthermore, (-)-loliolide suppressed the activation of mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling, whereas it activated nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling. Interestingly, the cytoprotective effects of (-)-loliolide against IFN-γ/TNF-α stimulation were significantly blocked upon inhibition of HO-1. Taken together, these results suggest that (-)-loliolide effectively suppressed the oxidative stress and inflammation by activating the Nrf2/HO-1 signaling in IFN-γ/TNF-α-stimulated HaCaT keratinocytes.

Environmental exposures and sleep outcomes: A review of evidence, potential mechanisms, and implications

Environmental exposures and poor sleep outcomes are known to have consequential effects on human health. This integrative review first seeks to present and synthesize existing literature investigating the relationship between exposure to various environmental factors and sleep health. We then present potential mechanisms of action as well as implications for policy and future research for each environmental exposure. Broadly, although studies are still emerging, empirical evidence has begun to show a positive association between adverse effects of heavy metal, noise pollution, light pollution, second-hand smoke, and air pollution exposures and various sleep problems. Specifically, these negative sleep outcomes range from subjective sleep manifestations, such as general sleep quality, sleep duration, daytime dysfunction, and daytime sleepiness, as well as objective sleep measures, including difficulties with sleep onset and maintenance, sleep stage or circadian rhythm interference, sleep arousal, REM activity, and sleep disordered breathing. However, the association between light exposure and sleep is less clear. Potential toxicological mechanisms are thought to include the direct effect of various environmental toxicants on the nervous, respiratory, and cardiovascular systems, oxidative stress, and inflammation. Nevertheless, future research is required to tease out the exact pathways of action to explain the associations between each environmental factor and sleep, to inform possible therapies to negate the detrimental effects, and to increase efforts in decreasing exposure to these harmful environmental factors to improve health.

Oxidative stress and impaired oligodendrocyte precursor cell differentiation in neurological disorders

Oligodendrocyte precursor cells (OPCs) account for 5% of the resident parenchymal central nervous system glial cells. OPCs are not only a back-up for the loss of oligodendrocytes that occurs due to brain injury or inflammation-induced demyelination (remyelination) but are also pivotal in plastic processes such as learning and memory (adaptive myelination). OPC differentiation into mature myelinating oligodendrocytes is controlled by a complex transcriptional network and depends on high metabolic and mitochondrial demand. Mounting evidence shows that OPC dysfunction, culminating in the lack of OPC differentiation, mediates the progression of neurodegenerative disorders such as multiple sclerosis, Alzheimer's disease and Parkinson's disease. Importantly, neurodegeneration is characterised by oxidative and carbonyl stress, which may primarily affect OPC plasticity due to the high metabolic demand and a limited antioxidant capacity associated with this cell type. The underlying mechanisms of how oxidative/carbonyl stress disrupt OPC differentiation remain enigmatic and a focus of current research efforts. This review proposes a role for oxidative/carbonyl stress in interfering with the transcriptional and metabolic changes required for OPC differentiation. In particular, oligodendrocyte (epi)genetics, cellular defence and repair responses, mitochondrial signalling and respiration, and lipid metabolism represent key mechanisms how oxidative/carbonyl stress may hamper OPC differentiation in neurodegenerative disorders. Understanding how oxidative/carbonyl stress impacts OPC function may pave the way for future OPC-targeted treatment strategies in neurodegenerative disorders.

The Nigral Coup in Parkinson's Disease by α-Synuclein and Its Associated Rebels

The risk of Parkinson's disease increases with age. However, the etiology of the illness remains obscure. It appears highly likely that the neurodegenerative processes involve an array of elements that influence each other. In addition, genetic, endogenous, or exogenous toxins need to be considered as viable partners to the cellular degeneration. There is compelling evidence that indicate the key involvement of modified α-synuclein (Lewy bodies) at the very core of the pathogenesis of the disease. The accumulation of misfolded α-synuclein may be a consequence of some genetic defect or/and a failure of the protein clearance system. Importantly, α-synuclein pathology appears to be a common denominator for many cellular deleterious events such as oxidative stress, mitochondrial dysfunction, dopamine synaptic dysregulation, iron dyshomeostasis, and neuroinflammation. These factors probably employ a common apoptotic/or autophagic route in the final stages to execute cell death. The misfolded α-synuclein inclusions skillfully trigger or navigate these processes and thus amplify the dopamine neuron fatalities. Although the process of neuroinflammation may represent a secondary event, nevertheless, it executes a fundamental role in neurodegeneration. Some viral infections produce parkinsonism and exhibit similar characteristic neuropathological changes such as a modest brain dopamine deficit and α-synuclein pathology. Thus, viral infections may heighten the risk of developing PD. Alternatively, α-synuclein pathology may induce a dysfunctional immune system. Thus, sporadic Parkinson's disease is caused by multifactorial trigger factors and metabolic disturbances, which need to be considered for the development of potential drugs in the disorder.

Implication of post-translationally modified SOD1 in pathological aging

Why certain people relish healthy aging throughout their life span while others suffer pathological consequences? In this review, we focus on some of the dominant paradigms of pathological aging, such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), and Parkinson's disease (PD), and predict that the antioxidant superoxide dismutase 1 (SOD1), when post-translationally modified by aging-associated oxidative stress, acts as a mechanism to accelerated aging in these age-related neurodegenerative diseases. Oxidative modifications of natively reduced SOD1 induce pathological confirmations such as misfolding, leading to a subsequent formation of monomeric, oligomeric, and multimeric aggregates. Misfolded SOD1 propagates like prions from cell to cell. These modified conformations are detected in brain tissues in ALS, AD, and PD, and are considered a contributing factor to their initial pathogenesis. We have also elaborated on oxidative stress-induced non-native modifications of SOD1 and offered a logistic argument on their global implication in accelerated or pathological aging in the context of ALS, AD, and PD.