Trends in oxidative aging theories

Pinpointing oxidative stress behind the white striping myopathy: depletion of antioxidant defenses, accretion of oxidized proteins and impaired proteostasis

BACKGROUND

This study aimed to investigate the molecular mechanisms involved in the onset of the white striping (WS) myopathy with particular attention to the role of oxidative stress and protein oxidation in the loss of meat quality.

RESULTS

It was found that WS-M (moderate degree; white stripes <1 mm thickness) and WS-S (severe degree; white stripes >1 mm thickness) breast presented higher pH, hardness, redness, lipid, and collagen content, and lower lightness than normal breast. Compared with the latter, WS-S had a more severe loss of protein thiols (70.7% less thiols than in N), reduced activity of antioxidant enzymes such as catalase (23 versus 40 U g^-1 ), glutathione peroxidase (0.21 versus 0.54 U g^-1 ), and superoxide dismutase (56 versus 73 U g^-1 ), and consequently, had greater accretion of thiobarbituric acid reactive substances (0.64 versus 0.22 mg MDAkg^-1 muscle), allysine (3.1 versus 1.9 nmol mg^-1 protein) and Schiff base structures (645 versus 258 fluorescent units). The analysis of sarcoplasmic proteins revealed that muscles severely affected by the myopathy suffered a chronic impairment of physiological (upregulation of sarcoplasmic reticulum Ca2+ ATPase, sarcalumenin and calsequestrin-2) and metabolic processes (downregulation of pyruvate kinase, creatine kinase, and l-lactate dehydrogenase).

CONCLUSION

The overexpression of ribonuclease / angiogenin inhibitor 1 and Kelch-like proteins in WS chicken breasts indicates altered protein turnover plausibly mediated by oxidative stress and accumulation of oxidized proteins. © 2020 Society of Chemical Industry.

Protective effect of vanillic acid in hydrogen peroxide-induced oxidative stress in D.Mel-2 cell line

The overproduction of reactive oxygen species (ROS) causes oxidative stress, such as Hydrogen peroxide (H2O2). Acute oxidative stress is one of the main reasons for cell death. In this study, the antioxidant properties of vanillic acid- a polyphenolic compound was evaluated. Therefore, this study aims to check the effectiveness of vanillic acid in H2O2-induced oxidative stress in D. Mel-2 cell line. The efficacy was determined by biochemical tests to check the ROS production. The cytotoxicity of H2O2 and vanillic acid was checked by MTT assay. The DNA fragmentation was visualized by gel electrophoresis. Protein biomarkers of oxidative stress were analyzed by western blotting. The results depict a promising antioxidant effect of vanillic acid. The IC50 value of vanillic acid and H2O2 was found 250 μg/ml and 125 μg/ml, respectively. The catalase activity, SOF, GPx, and PC was seen less in H2O2 treated group compared with the control and vanillic acid treated group. However, the TBRAS activity was hight in H2O2 treated group. The effect of H2O2 on DNA fragmentation was high as compared with vanillic acid-treated cells. The protein expression of Hsp70, IL-6 and iNOS was seen significant in a vanillic acid-treated group as compared with H2O2 treated group. These results reinforce that at low concentration, vanillic acid could be used as an antioxidant agent in the food and pharmaceutical industries.

Structural aspects of the aging invertebrate brain

Aging is characterized by a decline in neuronal function in all animal species investigated so far. Functional changes are accompanied by and may be in part caused by, structurally visible degenerative changes in neurons. In the mammalian brain, normal aging shows abnormalities in dendrites and axons, as well as ultrastructural changes in synapses, rather than global neuron loss. The analysis of the structural features of aging neurons, as well as their causal link to molecular mechanisms on the one hand, and the functional decline on the other hand is crucial in order to understand the aging process in the brain. Invertebrate model organisms like Drosophila and C. elegans offer the opportunity to apply a forward genetic approach to the analysis of aging. In the present review, we aim to summarize findings concerning abnormalities in morphology and ultrastructure in invertebrate brains during normal aging and compare them to what is known for the mammalian brain. It becomes clear that despite of their considerably shorter life span, invertebrates display several age-related changes very similar to the mammalian condition, including the retraction of dendritic and axonal branches at specific locations, changes in synaptic density and increased accumulation of presynaptic protein complexes. We anticipate that continued research efforts in invertebrate systems will significantly contribute to reveal (and possibly manipulate) the molecular/cellular pathways leading to neuronal aging in the mammalian brain.

Accelerated Aging and Age-Related Diseases (CVD and Neurological) Due to Air Pollution and Traffic Noise Exposure

The World Health Organization estimates that only approximately 25% of diversity in longevity is explained by genetic factors, while the other 75% is largely determined by interactions with the physical and social environments. Indeed, aging is a multifactorial process that is influenced by a range of environmental, sociodemographic, and biopsychosocial factors, all of which might act in concert to determine the process of aging. The global average life expectancy increased fundamentally over the past century, toward an aging population, correlating with the development and onset of age-related diseases, mainly from cardiovascular and neurological nature. Therefore, the identification of determinants of healthy and unhealthy aging is a major goal to lower the burden and socioeconomic costs of age-related diseases. The role of environmental factors (such as air pollution and noise exposure) as crucial determinants of the aging process are being increasingly recognized. Here, we critically review recent findings concerning the pathomechanisms underlying the aging process and their correlates in cardiovascular and neurological disease, centered on oxidative stress and inflammation, as well as the influence of prominent environmental pollutants, namely air pollution and traffic noise exposure, which is suggested to accelerate the aging process. Insight into these types of relationships and appropriate preventive strategies are urgently needed to promote healthy aging.

Beneficial and Detrimental Effects of Reactive Oxygen Species on Lifespan: A Comprehensive Review of Comparative and Experimental Studies

Aging is the greatest risk factor for a multitude of diseases including cardiovascular disease, neurodegeneration and cancer. Despite decades of research dedicated to understanding aging, the mechanisms underlying the aging process remain incompletely understood. The widely-accepted free radical theory of aging (FRTA) proposes that the accumulation of oxidative damage caused by reactive oxygen species (ROS) is one of the primary causes of aging. To define the relationship between ROS and aging, there have been two main approaches: comparative studies that measure outcomes related to ROS across species with different lifespans, and experimental studies that modulate ROS levels within a single species using either a genetic or pharmacologic approach. Comparative studies have shown that levels of ROS and oxidative damage are inversely correlated with lifespan. While these studies in general support the FRTA, this type of experiment can only demonstrate correlation, not causation. Experimental studies involving the manipulation of ROS levels in model organisms have generally shown that interventions that increase ROS tend to decrease lifespan, while interventions that decrease ROS tend to increase lifespan. However, there are also multiple examples in which the opposite is observed: increasing ROS levels results in extended longevity, and decreasing ROS levels results in shortened lifespan. While these studies contradict the predictions of the FRTA, these experiments have been performed in a very limited number of species, all of which have a relatively short lifespan. Overall, the data suggest that the relationship between ROS and lifespan is complex, and that ROS can have both beneficial or detrimental effects on longevity depending on the species and conditions. Accordingly, the relationship between ROS and aging is difficult to generalize across the tree of life.

Lipid conformational order and the etiology of cataract and dry eye

Lens and tear film lipids are as unique as the systems they reside in. The major lipid of the human lens is dihydrosphingomylein, found in quantity only in the lens. The lens contains a cholesterol to phospholipid molar ratio as high as 10:1, more than anywhere else in the body. Lens lipids contribute to maintaining lens clarity, and alterations in lens lipid composition due to age are likely to contribute to cataract. Lens lipid composition reflects adaptations to the unique characteristics of the lens: no turnover of lens lipids or proteins; the lowest amount of oxygen of any tissue; and contains almost no intracellular organelles. The tear film lipid layer (TFLL) is also unique. The TFLL is a thin (100 nm) layer of lipid on the surface of tears covering the cornea that contributes to tear film stability. The major lipids of the TFLL are wax esters and cholesterol esters that are not found in the lens. The hydrocarbon chains associated with the esters are longer than those found anywhere else in the body (as long as 32 carbons), and many are branched. Changes in the composition and structure of the 30,000 different moieties of TFLL contribute to the instability of tears. The focus of the current review is how spectroscopy has been used to elucidate the relationships between lipid composition, conformational order and function, and the etiology of cataract and dry eye.

Folic acid prevents habituation memory impairment and oxidative stress in an aging model induced by D-galactose

The present study aimed to evaluate the effect of folic acid treatment in an animal model of aging induced by D-galactose (D-gal). For this propose, adult male Wistar rats received D-gal intraperitoneally (100 mg/kg) and/or folic acid orally (5 mg/kg, 10 mg/kg or 50 mg/kg) for 8 weeks. D-gal caused habituation memory impairment, and folic acid (10 mg/kg and 50 mg/kg) reversed this effect. However, folic acid 50 mg/kg per se caused habituation memory impairment. D-gal increased the lipid peroxidation and oxidative damage to proteins in the prefrontal cortex and hippocampus from rats. Folic acid (5 mg/kg, 10 mg/kg, or 50 mg/kg) partially reversed the oxidative damage to lipids in the hippocampus, but not in the prefrontal cortex, and reversed protein oxidative damage in the prefrontal cortex and hippocampus. D-gal induced synaptophysin and BCL-2 decrease in the hippocampus and phosphorylated tau increase in the prefrontal cortex. Folic acid was able to reverse these D-gal-related alterations in the protein content. The present study shows folic acid supplementation as an alternative during the aging to prevent cognitive impairment and brain alterations that can cause neurodegenerative diseases. However, additional studies are necessary to elucidate the effect of folic acid in aging.

Do polyunsaturated fatty acids protect against bone loss in our aging and osteoporotic population?

Age-related bone loss is inevitable in both men and women and there will soon be more people of extreme old age than ever before. Osteoporosis is a common chronic disease and as the proportion of older people, rate of obesity and the length of life increases, a rise in age-related degenerating bone diseases, disability, and prolonged dependency is projected. Fragility fractures are one of the most severe complications associated with both primary and secondary osteoporosis and current treatment strategies target weight-bearing exercise and pharmacological intervention, both with limited long-term success. Obesity and osteoporosis are intimately interrelated, and diet is a variable that plays a significant role in bone regeneration and repair. The Western Diet is characterized by its unhealthy components, specifically excess amounts of saturated fat intake. This review examines the impact of saturated and polyunsaturated fatty acid consumption on chronic inflammation, osteogenesis, bone architecture, and strength and explores the hypothesis that dietary polyunsaturated fats have a beneficial effect on osteogenesis, reducing bone loss by decreasing chronic inflammation, and activating bone resorption through key cellular and molecular mechanisms in our aging population. We conclude that aging, obesity and a diet high in saturated fatty acids significantly impairs bone regeneration and repair and that consumption of ω-3 polyunsaturated fatty acids is associated with significantly increased bone regeneration, improved microarchitecture and structural strength. However, ω-6 polyunsaturated fatty acids were typically pro-inflammatory and have been associated with an increased fracture risk. This review suggests a potential role for ω-3 fatty acids as a non-pharmacological dietary method of reducing bone loss in our aging population. We also conclude that contemporary amendments to the formal nutritional recommendations made by the Food and Nutrition Board may be necessary such that our aging population is directly considered.

Melatonin Alleviates Hypoxia-Induced Apoptosis of Granulosa Cells by Reducing ROS and Activating MTNR1B-PKA-Caspase8/9 Pathway

In mammalian ovaries, the avascular environment within follicular cavity is supposed to cause hypoxic status in granulosa cells (GCs), leading to apoptotic cell death accompanied by cumulative reactive oxygen species (ROS) production. Melatonin (N-acetyl-5-methoxytryptamine, MT), a broad-spectrum antioxidant that exists in porcine follicle fluid, was suggested to maintain GCs survival under stress conditions. In this study, using the established hypoxic model (1% O₂) of cultured porcine GCs, we explored the effect of MT on GCs apoptosis. The results showed that MT restored cell viability and reduced the apoptosis of GCs during hypoxia exposure. In addition, GCs treated with MT exhibited decreased ROS levels and increased expression of antioxidant enzymes including heme oxygenase-1 (HO-1), glutathione S-transferase (GST), superoxide dismutase 1 (SOD1), and catalase (CAT) upon hypoxia incubation. Moreover, the hypoxia-induced expression of cleaved caspase 3, 8, and 9 was significantly inhibited after MT treatment. In contrast, blocking melatonin receptor 2 (MTNR1B) with a competitive antagonist 4-phenyl-2-propionamidotetralin (4P-PDOT) diminished the inhibitory effects of MT on caspase 3 activation. By detecting levels of protein kinase (PKA), a downstream kinase of MTNR1B, we further confirmed the involvement of MT–MTNR1B signaling in mediating GCs protection during hypoxia stress. Together, the present data provide mechanistic evidence suggesting the role of MT in defending GCs from hypoxia-induced apoptosis.

Lipid hydroperoxides in nutrition, health, and diseases

Research on lipid peroxidation in food degradation, oil and fat nutrition, and age-related diseases has gained significant international attention for the view of improvement of societal health and longevity. In order to promote basic studies on these topics, a chemiluminescence detection-high performance liquid chromatography instrument using a high-sensitivity single photon counter as a detector was developed. This instrument enabled us to selectively detect and quantify lipid hydroperoxides, a primary product of lipid peroxidation reactions, as hydroperoxide groups at the lipid class level. Furthermore, an analytical method using liquid chromatography-tandem mass spectrometry has been established to discriminate the position and stereoisomerization of hydroperoxide groups in lipid hydroperoxides. Using these two methods, the reaction mechanisms of lipid peroxidation in food and in the body have been confirmed.

Antioxidant effects of ankaferd blood stopper doped polyvinyl pyrolidon in an experimental model created in insect

This research evaluated Ankaferd Blood Stopper (ABS)-doped Polyvinylpyrrolidone (PVP) nanofiber layers which were produced with the electrospinning method for their potential for co-use in response to oxidative stress. As a result of the use of such a preparation (ABS doped PVP) in long-term treatments, the response to oxidative stress was compared to biochemical parameters, and its effect on sex was also aimed to be determined. For this purpose, Drosophila melanogaster foods were coated with 10% PVP, ABS (2 ml) and PVP-ABS. In total, 300 flies were randomized into 6 groups, each consisting of 25 female and 25 male insects, and the insects were fed with the determined coated mediums. The effects of foods on adult flies were tested for biochemical changes (Malondialdehyde-MDA and Total oxidation status-TOS, Glutathione-S-Transferase-GST, Catalase-CAT and Superoxide dismutase-SOD activities, Total antioxidant capacity-TAS) at the end of ten days. It was determined that the separate use of the two substances increased the amount of MDA in both sexes. It was found that the combined use of PVP-ABS had a positive effect similar to the control by increasing the antioxidant enzymes (SOD, CAT, GST). Feeding with ABS-doped PVP in the male insects reduced TOS (2.00 ± 0.01 μmol H₂O₂Eq/L), but the female insects were found to have higher OSI (40.00 ± 0.01 μmol H₂O₂Eq/L). As a result, PVP-ABS may be used together as an antioxidant, but more detailed studies are needed for their safe use on both sexes.

c-Jun N-Terminal Kinase Inhibitors as Potential Leads for New Therapeutics for Alzheimer's Diseases

Alzheimer's Disease (AD) is becoming more prevalent as the population lives longer. For individuals over 60 years of age, the prevalence of AD is estimated at 40.19% across the world. Regarding the cognitive decline caused by the disease, mitogen-activated protein kinases (MAPK) pathways such as the c-Jun N-terminal kinase (JNK) pathway are involved in the progressive loss of neurons and synapses, brain atrophy, and augmentation of the brain ventricles, being activated by synaptic dysfunction, oxidative stress, and excitotoxicity. Nowadays, AD symptoms are manageable, but the disease itself remains incurable, thus the inhibition of JNK3 has been explored as a possible therapeutic target, considering that JNK is best known for its involvement in propagating pro-apoptotic signals. This review aims to present biological aspects of JNK, focusing on JNK3 and how it relates to AD. It was also explored the recent development of inhibitors that could be used in AD treatment since several drugs/compounds in phase III clinical trials failed. General aspects of the MAPK family, therapeutic targets, and experimental treatment in models are described and discussed throughout this review.

The mental health impact of parole on families of indeterminate-sentenced prisoners in England and Wales

BACKGROUND

The indeterminate sentence of Imprisonment for Public Protection (IPP), was created in England and Wales in 2003. After its abolition in 2012, many IPP-prisoners have become stuck in the prison system, facing considerable problems of sentence progression. The extant literature makes clear that the uncertainty and hopelessness caused by the indeterminacy of the IPP sentence are compounded by the negative impacts experienced by families and others providing support to people serving these sentences.

AIMS

The mental strains caused for family members by the IPP sentence were examined. Of particular interest is the role and weight of the parole process experience, and its potential mental and physiological health impact on families.

METHODS

This article draws on findings from two qualitative research projects conducted with families of prisoners serving the IPP sentence in England and Wales. Their experiences will be examined by reference to literature on the mental health impact of indeterminate sentences on prisoners and their families and the wider literature on the symbiotic harms of imprisonment for families. The aim was to add to this by focusing on families' experiences of cumulative stress caused by the sentence.

FINDINGS

We demonstrate that the IPP parole process exerts specific weight and mental strains on family members occupying the negative end of the stress spectrum. Drawing on a body of neuroscientific, neuroendocrinological and criminological literature, we argue that these mental health impacts on families may represent a public health risk in need of practical and policy mitigation.

IMPLICATIONS

There is a pressing need for recognition of what are often hidden symbiotic harms experienced by families of people sentenced to IPP. Families require more information as well as considerably greater practical and emotional support on an institutional and communal level.

Effects of alpha-mangostin on memory senescence induced by high glucose in human umbilical vein endothelial cells

Objective(s):

Hyperglycemia induces cellular senescence in various body cells, such as vascular endothelial cells. Since the vessels are highly distributed in the body and nourish all tissues, vascular damages cause diabetes complications such as kidney failure and visual impairment. Alpha-mangostin is a xanthone found in mangosteen fruit with protective effects in metabolic syndrome and diabetes. This paper has investigated the protective effect of this xanthone against high glucose-induced memory senescence in human vascular endothelial cells (HUVECs) in the presence of metformin, as a positive control.

Materials and Methods:

To induce the memory senescence model, HUVECs, after three days incubation with high glucose, were incubated with normal glucose for another three days, and for whole six days, cells were treated with metformin (50 µM) or alpha-mangostin (1.25 µM). On the last day, cell viability by MTT assay, oxidative stress by fluorimetric assay, the number of senescent cells by SA beta-galactosidase staining kit, and secretory interleukin-6 by ELISA kit were measured. SIRT1 and P53 proteins were also evaluated by Western blotting.

Results:

Metformin and alpha-mangostin significantly increased cell viability, decreased reactive oxygen species, and senescence-associated beta-galactosidase in HUVECs incubated in metabolic memory condition. Generally, metabolic memory increased p53 and acetyl-P53 and decreased SIRT1 proteins in HUVECs, which were reversed by alpha-mangostin and metformin.

Conclusion:

These data exhibit that alpha-mangostin, comparable to metformin, protects endothelial cells against metabolic memory-induced senescence, which is likely via SIRT1.

Genes affecting the extension of chronological lifespan in Schizosaccharomyces pombe (fission yeast)

So far, more than 70 genes involved in the chronological lifespan (CLS) of Schizosaccharomyces pombe (fission yeast) have been reported. In this mini‐review, we arrange and summarize these genes based on the reported genetic interactions between them and the physical interactions between their products. We describe the signal transduction pathways that affect CLS in S. pombe: target of rapamycin complex 1, cAMP‐dependent protein kinase, Sty1, and Pmk1 pathways have important functions in the regulation of CLS extension. Furthermore, the Php transcription complex, Ecl1 family proteins, cyclin Clg1, and the cyclin‐dependent kinase Pef1 are important for the regulation of CLS extension in S. pombe. Most of the known genes involved in CLS extension are related to these pathways and genes. In this review, we focus on the individual genes regulating CLS extension in S. pombe and discuss the interactions among them.

Oxidative damage mechanism in Saccharomyces cerevisiae cells exposed to tetrachlorobisphenol A

Tetrachlorobisphenol A (TCBPA) can promote intracellular reactive oxygen species (ROS) accumulation. However, limited attention has been given to mechanisms underlying TCBPA exposure-associated ROS accumulation. Here, such mechanisms were explored in the simple eukaryotic model organism Saccharomyces cerevisiae exposed to multiple concentrations of TCBPA. Addition of diphenyleneiodonium, a specific inhibitor of NADPH oxidase, blocked TCBPA treatment-associated intracellular ROS accumulation. NADPH oxidase can be activated by calcineurin, mitogen-activated protein kinase (MAPK), and tyrosine kinase. Therefore, corresponding specific inhibition respectively on these three kinases was performed and results suggested that the Ca²⁺ signaling pathway, MAPK pathway, and tyrosine kinase pathway all contributed to the TCBPA exposure-associated intracellular ROS accumulation. In addition, TCBPA exposure-associated up-regulation of genes involved in ROS production and down-regulation of catalase promoted ROS accumulation in S. cerevisiae. To sum up, our current results provide insights into the understanding of TCBPA exposure-associated ROS accumulation.

Isolinderalactone Induces Cell Death via Mitochondrial Superoxide- and STAT3-Mediated Pathways in Human Ovarian Cancer Cells

The mortality rate of ovarian cancer (OC) worldwide increases with age. OC is an often fatal cancer with a curative rate of only 20-30%, as symptoms often appear after disease progression. Studies have reported that isolinderalactone (ILL), a furanosesquiterpene derivative extracted from the dried root of Lindera aggregata, can inhibit several cancer cell lines' growth. However, the molecular mechanisms underlying ILL activities in human OC cells remain unexplored. This study investigated the antitumor activities of ILL in human OC cells by inducing mitochondrial superoxide (mtSO) and JAK-signal transducer and activator of transcription 3 (STAT3)-dependent cell death. ILL caused cell death in SKOV-3 and OVCAR-3 cells and increased the cell proportion in the subG1 phase. Additionally, ILL significantly induced mtSO production and reduced ROS production. Moreover, ILL downregulated mitochondrial membrane potential and the expression levels of anti-apoptotic Bcl-2 family proteins and superoxide dismutase (SOD)2. Results showed that ILL decreased phosphorylation of serine 727 and tyrosine 705 of STAT3 and expression of survivin, a STAT3-regulated gene. Furthermore, ILL-induced cell death was reversed by pretreatment of Mito-TEMPO, a mitochondria-specific antioxidant. These results suggest that ILL induces cell death by upregulation of mtSO, downregulation of mitochondrial SOD2, and inactivation of the STAT3-mediated pathway.

Enhancement of Intracellular Calcium Ion Mobilization by Moderately but Not Highly Positive Material Surface Charges

Electrostatic forces at the cell interface affect the nature of cell adhesion and function; but there is still limited knowledge about the impact of positive or negative surface charges on cell-material interactions in regenerative medicine. Titanium surfaces with a variety of zeta potentials between −90 mV and +50 mV were generated by functionalizing them with amino polymers, extracellular matrix proteins/peptide motifs and polyelectrolyte multilayers. A significant enhancement of intracellular calcium mobilization was achieved on surfaces with a moderately positive (+1 to +10 mV) compared with a negative zeta potential (−90 to −3 mV). Dramatic losses of cell activity (membrane integrity, viability, proliferation, calcium mobilization) were observed on surfaces with a highly positive zeta potential (+50 mV). This systematic study indicates that cells do not prefer positive charges in general, merely moderately positive ones. The cell behavior of MG-63s could be correlated with the materials’ zeta potential; but not with water contact angle or surface free energy. Our findings present new insights and provide an essential knowledge for future applications in dental and orthopedic surgery.

An overview on recent in vivo biological application of cerium oxide nanoparticles

Cerium oxide nanoparticles (CNPs) possess a great potential as therapeutic agents due to their ability to self-regenerate by reversibly switching between two valences +3 and +4. This article reviews recent articles dealing with in vivo studies of CNPs towards Alzheimer's disease, obesity, liver inflammation, cancer, sepsis, amyotrophic lateral sclerosis, acute kidney injury, radiation-induced tissue damage, hepatic ischemia reperfusion injury, retinal diseases and constipation. In vivo anti-cancer studies revealed the effectiveness of CNPs to reduce tumor growth and angiogenesis in melanoma, ovarian, breast and retinoblastoma cancer cell-induced mice, with their conjugation with folic acid, doxorubicin, CPM, or CXC receptor-4 antagonist ligand eliciting higher efficiency. After conjugation with triphenylphosphonium or magnetite nanoparticles, CNPs were shown to combat Alzheimer's disease by reducing amyloid-β, glial fibrillary acidic protein, inflammatory and oxidative stress markers in mice. By improving muscle function and longevity, the citrate/EDTA-stabilized CNPs could ameliorate amyotrophic lateral sclerosis. Also, they could effectively reduce obesity in mice by scavenging ROS and reducing adipogenesis, triglyceride synthesis, GAPDH enzyme activity, leptin and insulin levels. In CCl4-induced rats, stress signaling pathways due to inflammatory cytokines, liver enzymes, oxidative and endoplasmic reticulum messengers could be attenuated by CNPs. Commercial CNPs showed protective effects on rats with hepatic ischemia reperfusion and peritonitis-induced hepatic/cardiac injuries by decreasing oxidative stress and hepatic/cardiac inflammation. The same CNPs could improve kidney function by diminishing renal superoxide, hyperglycemia and tubular damage in peritonitis-induced acute kidney injury in rats. Radiation-induced lung and testicular tissue damage could be alleviated in mice, with the former showing improvement in pulmonary distress and bronchoconstriction and the latter exhibiting restoration in spermatogenesis rate and spermatid/spermatocyte number. Through enhancement of gastrointestinal motility, the CNPs could alleviate constipation in both young and old rats. They could also protect rat from light-induced retinal damage by slowing down neurodegenerative process and microglial activation.

The Protective Effect of Kolaviron on Molecular, Cellular, and Behavioral Characterization of Cerebellum in the Rat Model of Demyelinating Diseases

INTRODUCTION

This study aimed at assessing the protective mechanisms of Kolaviron (KV) on the cerebellum in a rat model of demyelination.

METHODS

Twenty-eight male Wistar rats were used in the present study. They were randomly divided into 4 groups of 7 rats. Group A (control) received corn oil (0.5 mL/kg/d); group B received 0.2% Cuprizone (CPZ); group C was treated with 200 mg/kg/d of KV, and group D received 0.2% CPZ and 200 mg/kg/d KV for 6 weeks. CPZ powder was mixed with the regular diet while KV was dissolved in corn oil and administered orally. A behavioral test was conducted at the termination of the experiment. Thereafter, the animals were sacrificed and their brains were removed with the excision of the cerebellum. A part of the cerebelli underwent tissue processing with a series of 5 μm thick sections cut from paraffin blocks for histological and immunohistochemical assessment. Besides, the remaining cerebellar tissues were homogenized for the spectrophotometric assays of Oxidative Stress (OS) parameters.

RESULTS

The current research findings revealed minimal weight gain following CPZ treatment, but significant weight increase in KV-treated rats. CPZ treatment was associated with a reduction in the number of the line crossed, rearing frequency, rearing duration, center square entry, and center square duration; however, it increased the freezing time, i.e. significantly reversed in the KV-treated animals. Oxidative markers, such as Superoxide Dismutase (SOD) and GPx were reduced in CPZ-treated rats with elevated MDA levels. However, these data were significantly reversed by the co-administration of CPZ and KV. At the tissue level, the cerebellar cortex was characterized by poorly defined layers, cryptic granules, as well as chromatolysis and pyknotic Purkinje cells with the evidence of hypertrophic astrogliosis.

CONCLUSION

CPZ treatment significantly depressed locomotor and exploratory activities. Furthermore, it increased OS and cerebellar toxicity. However, KV intervention significantly enhanced behavioral functions and ameliorated CPZ-induced cerebellar degeneration. Moreover, it considerably regulated OS markers in the cerebellum of the rat model of demyelinating diseases.

SIRT1/FOXO3a axis plays an important role in the prevention of mandibular bone loss induced by 1,25(OH)2D deficiency

It has been reported that 1,25 dihydroxyvitamin D [1,25(OH)2D] deficiency leads to the loss of mandibular bone, however the mechanism is unclear. We investigated whether the Sirt1/FOXO3a signaling pathway is involved in this process. Using a 1,25(OH)2D deficiency model induced by genetic deletion in mice of 25-hydroxyvitamin D-1α hydroxylase [1α(OH)ase-/- mice]. We first documented a sharp reduction of expression levels of Sirt1 in the 1α(OH)ase-/- mice in vivo. Next, we demonstrated dose-dependent upregulation of Sirt1 by treatment with exogenous 1,25(OH)2D3in vitro. We then identified a functional VDR binding site in the Sirt1 promoter. By crossing Prx1-Sirt1 transgenic mice with 1α(OH)ase-/- mice we demonstrated that the overexpression of Sirt1 in mesenchymal stem cells (MSCs) greatly improved the 1α(OH)ase-/- mandibular bone loss phenotype by increasing osteoblastic bone formation and reducing osteoclastic bone resorption. In mechanistic studies, we showed, in 1α(OH)ase-/- mice, decreases of Sirt1 and FoxO3a, an increase in oxidative stress as reflected by a reduction of the antioxidant enzymes peroxiredoxin1 (Prdx1), SOD1 and SOD2 expression, and an increase of markers for osteocyte senescence and senescence associated secretory phenotypes (SASP), including β-galactosidase (β-gal), p16, p53 and p21. The targeted overexpression of Sirt1 in the 1α(OH)ase-/- mice restored the expression levels of these molecules. Finally, we demonstrated that a Sirt1 agonist can upregulate FOXO3a activity by increasing deacetylation and nuclear translocation. Overall, results from this study support the concept that targeted increases in Sirt1/FOXO3a signaling levels can greatly improve the bone loss caused by 1,25(OH)2D deficiency.

Mitochondrial threshold for H2O2 release in skeletal muscle of mammals

The aim of the study was to evaluate the interplay between mitochondrial respiration and H₂O₂ release during the transition from basal non-phosphorylating to maximal phosphorylating states. We conducted a large scale comparative study of mitochondrial oxygen consumption, H₂O₂ release and electron leak (% H₂O₂/O) in skeletal muscle mitochondria isolated from mammal species ranging from 7 g to 500 kg. Mitochondrial fluxes were measured at different steady state rates in presence of pyruvate, malate, and succinate as respiratory substrates. Every species exhibited a burst of H₂O₂ release from skeletal muscle mitochondria at a low rate of oxidative phosphorylation, essentially once the activity of mitochondrial oxidative phosphorylation reached 26% of the maximal respiration. This threshold for ROS generation thus appears as a general characteristic of skeletal muscle mitochondria in mammals. These findings may have implications in situations promoting succinate accumulation within mitochondria, such as ischemia or hypoxia.

Restoration of L-OPA1 alleviates acute ischemic stroke injury in rats via inhibiting neuronal apoptosis and preserving mitochondrial function

BACKGROUND

Ischemic stroke can induce changes in mitochondrial morphology and function. As a regulatory gene in mitochondria, optic atrophy 1 (OPA1) plays a pivotal role in the regulation of mitochondrial dynamics and other related functions. However, its roles in cerebral ischemia-related conditions are barely understood.

METHODS

Cultured rat primary cortical neurons were respectively transfected with OPA1-v1ΔS1-encoding and OPA1-v1-encoding lentivirus before exposure to 2-h oxygen-glucose deprivation (OGD) and subsequent reoxygenation (OGD/R). Adult male SD rats received an intracranial injection of AAV-OPA1-v1ΔS1 and were subjected to 90 min of transient middle cerebral artery occlusion (tMCAO) followed by reperfusion. OPA1 expression and function were detected by in vitro and in vivo assays.

RESULTS

OPA1 was excessively cleaved after cerebral ischemia/reperfusion injury, both in vitro and in vivo. Under OGD/R condition, compared with that of the LV-OPA1-v1-treated group, the expression of OPA1-v1ΔS1 efficiently restored L-OPA1 level and alleviated neuronal death and mitochondrial morphological damage. Meanwhile, the expression of OPA1-v1ΔS1 markedly improved cerebral ischemia/reperfusion-induced motor function damage, attenuated brain infarct volume, neuronal apoptosis, mitochondrial bioenergetics deficits, oxidative stress, and restored the morphology of mitochondrial cristae and mitochondrial length. It also preserved the mitochondrial integrity and reinforced the mtDNA content and expression of mitochondrial biogenesis factors in ischemic rats.

INTERPRETATION

Our results demonstrate that the stabilization of L-OPA1 protects ischemic brains by reducing neuronal apoptosis and preserving mitochondrial function, suggesting its significance as a promising therapeutic target for stroke prevention and treatment.

The impact of ageing on lipid-mediated regulation of adult stem cell behavior and tissue homeostasis

Adult stem cells sustain tissue homeostasis throughout life and provide an important reservoir of cells capable of tissue repair in response to stress and tissue damage. Age-related changes to stem cells and/or the specialized niches that house them have been shown to negatively impact stem cell maintenance and activity. In addition, metabolic inputs have surfaced as another crucial layer in the control of stem cell behavior (Chandel et al., 2016; Folmes and Terzic, 2016; Ito and Suda, 2014; Mana et al., 2017; Shyh-Chang and Ng, 2017). Here, we will present a brief review of how lipid metabolism influences adult stem cell behavior under homeostatic conditions and speculate on how changes in lipid metabolism may impact stem cell ageing. This review considers the future of lipid metabolism research in stem cells, with the long-term goal of identifying mechanisms that could be targeted to counter or slow the age-related decline in stem cell function.

Mitochondria: A Galaxy in the Hematopoietic and Leukemic Stem Cell Universe

Mitochondria are the main fascinating energetic source into the cells. Their number, shape, and dynamism are controlled by the cell’s type and current behavior. The perturbation of the mitochondrial inward system via stress response and/or oncogenic insults could activate several trafficking molecular mechanisms with the intention to solve the problem. In this review, we aimed to clarify the crucial pathways in the mitochondrial system, dissecting the different metabolic defects, with a special emphasis on hematological malignancies. We investigated the pivotal role of mitochondria in the maintenance of hematopoietic stem cells (HSCs) and their main alterations that could induce malignant transformation, culminating in the generation of leukemic stem cells (LSCs). In addition, we presented an overview of LSCs mitochondrial dysregulated mechanisms in terms of (1) increasing in oxidative phosphorylation program (OXPHOS), as a crucial process for survival and self-renewal of LSCs,(2) low levels of reactive oxygen species (ROS), and (3) aberrant expression of B-cell lymphoma 2 (Bcl-2) with sustained mitophagy. Furthermore, these peculiarities may represent attractive new “hot spots” for mitochondrial-targeted therapy. Finally, we remark the potential of the LCS metabolic effectors to be exploited as novel therapeutic targets.

Effect of Anoectochilus roxburghii flavonoids extract on H2O2 - Induced oxidative stress in LO2 cells and D-gal induced aging mice model

ETHNOPHARMACOLOGICAL RELEVANCE

Anoectochilus roxburghii (A. roxburghii) is a popular folk medicine in many Asian countries, which has been used traditionally for treatment of some diseases such as diabetes, tumors, hyperlipemia, and hepatitis. The ethanol extract from A. roxburghii was recently shown to exert better ability to scavenge free radicals in vitro and possess antioxidant on natural aging mice in vivo.

AIM OF THE STUDY

This study is to characterize the chemical composition, and investigate the protective effect of the A. roxburghii flavonoids extract (ARF) against hydrogen peroxide (H₂O₂)-induced oxidative stress in LO2 cells in vitro and D-galactose (D-gal)-induced aging mice model in vivo, and explore the underlying mechanisms.

MATERIALS AND METHODS

The chemical components of the flavonoids extract fromA. roxburghii were detected by ultraperformance lipid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). H₂O₂ was used to establish an oxidative stress model in LO2 cells. Cytotoxic and protective effects of ARF on the LO2 cells were determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Moreover, the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA) in cell supernatants were measured by commercial reagent kits. Kun-Ming mice were induced to aging with D-gal (400 mg/kg, BW) by subcutaneous injection for 58 days. From the 28th day to the 58th day of D-gal treatment, ARF (122.5, 245 and 490 mg/kg, BW) and vitamin E (100 mg/kg, BW) were orally administrated to aging mice once a day for consecutive 30 days. After 25 days of the treatment with ARF, learning and memory were assessed using Morris Water Maze (MWM). At the end of the test period, the animals were euthanized by cervical dislocation, and the levels of SOD, GSH-PX, and MDA in serum, liver homogenates and brain homogenates were measured. The levels of monoamine oxidase (MAO) and acetylcholinesterase (AchE) were determined in brain homogenates. Skin and liver histopathological morphology were observed by H&E staining. Furthermore, antioxidant-related gene expression levels in the liver were carried out by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

Nine flavonoids were identified in the extracts of A. roxburghii. In vitro assay, a high concentration of ARF (>612.5 μg/ml) reduced the survival rate and had toxic effects on LO2 cells. In addition, ARF (245 μg/ml, 490 μg/ml) and Vitamin C (200 μg/ml) markedly inhibited generations of MDA and increased activities of SOD, GSH-PX in H₂O₂-induced LO2 cells supernatants. In vivo assay, ARF (122.5 mg/kg, 245 mg/kg and 490 mg/kg) and Vitamin E (100 mg/kg) not only ameliorated learning and memory ability but also improved skin and liver pathological alterations. Strikingly, ARF significantly decreased MDA and MAO levels, markedly enhanced antioxidant enzyme (SOD and GSH-PX) activities. Further, compared to the D-gal group, ARF could obviously up-regulate glutathione peroxidase-1 (GPx-1) and glutathione peroxidase-4 (GPx-4) mRNA levels.

CONCLUSIONS

These findings suggested that ARF protects LO2 cells against H₂O₂-induced oxidative stress and exerts the potent anti-aging effects in D-gal aging mice model, which may be related to the inhibition of oxidative stress. Flavonoid compounds may contribute to the anti-oxidative capability and modulating aging.

The safety, immunological benefits, and efficacy of ginseng in organ transplantation

Korean ginseng (Panax ginseng) is associated with a variety of therapeutic effects, including antioxidative, anti-inflammatory, vasorelaxative, antiallergic, antidiabetic, and anticancer effects. Accordingly, the use of ginseng has reached an all-time high among members of the general public. However, the safety and efficacy of ginseng in transplant recipients receiving immunosuppressant drugs have still not been elucidated. Transplantation is the most challenging and complex of surgical procedures and may require causation for the use of ginseng. In this regard, we have previously examined the safety, immunological benefits, and protective mechanisms of ginseng with respect to calcineurin inhibitor-based immunosuppression, which is the most widely used regimen in organ transplantation. Using an experimental model of calcineurin inhibitor-induced organ injury, we found that ginseng does not affect drug levels in the peripheral blood and tissue, favorably regulates immune response, and protects against calcineurin inhibitor-induced nephrotoxicity and pancreatic islet injury. On the basis of our experimental studies and a review of the related literature, we propose that ginseng may provide benefits in organ transplant recipients administered calcineurin inhibitors. Through the present review, we aimed to briefly discuss our current understanding of the therapeutic benefits of ginseng related to transplant patient survival.

Antioxidant and anti-aging activities of polysaccharides from Cordyceps cicadae

Cordyceps cicadae is a traditional Chinese medicine with high nutritional value and biological activities. Previously, we reported on the antioxidant activity associated with the polysaccharides from Cordyceps cicadae (CP). To further explore which of the fraction of CP had the greatest potency, in here, the in vitro antioxidant and in vivo anti-aging activities of the fractions CP30-CP80 of CP were evaluated. The in vitro antioxidant activity results revealed that all the fractions (i.e. CP30-CP80) were potent with CP70 as the most potent. Notably, CP70 prolonged the lifespan of Drosophila (P < 0.05), increased the activities of catalase (CAT) and glutathione peroxidase (GSH-Px) (P < 0.01), and inhibited the formation of malondialdehyde (MDA) (P < 0.01). Additionally, CP70 upregulated the expression level of antioxidant-related genes CAT, SOD1 and MTH in Drosophila (P < 0.05). These results indicated that CP70 may prolong the lifespan of Drosophila through the up-regulation of the expression level of antioxidant-related genes CAT, SOD1 and MTH in Drosophila. Thus, polysaccharides from Cordyceps cicadae possess significant antioxidant and anti-aging activities, and could be explored as a new dietary supplement to slow down the aging process.

A novel exopolysaccharide produced by Lactobacillus coryniformis NA-3 exhibits antioxidant and biofilm-inhibiting properties in vitro

Background

Exopolysaccharides (EPSs) secreted from lactic acid bacteria are carbohydrate polymers with reported biological activities. In this study, we extracted and characterized the composition as well as antioxidant and biofilm-inhibitory properties of EPS from Lactobacillus coryniformis NA-3 isolated from northeast Chinese sauerkraut (Suan Cai).

Methods

Lactobacillus coryniformis NA-3 was identified with 16S rDNA amplification and Neighbor Joining (NJ) phylogenetic analysis. EPS derived from Lactobacillus coryniformis NA-3 (EPS-NA3) was analyzed, including compositions by high-performance liquid chromatography (HPLC), functional groups by Fourier-transform infrared spectroscopy (FT-IR) and glycosidic bond configuration by Hydrogen-1 Nuclear Magnetic Resonance (¹H NMR). Antioxidant activity of EPS was evaluated with hydroxyl and superoxide radical-scavenging. Anti-biofilm activities of EPS-NA3 were checked through inhibition and dispersion.

Results

The monosaccharide composition of EPS included α-rhamnose, α-mannose, α-galactose, and α-glucose in a ratio of 2.6:1.0:5.0:3.3. The free radical-scavenging abilities of EPS-NA3 were 37.77% ± 1.56% and 78.87% ± 3.07% on hydroxyl and superoxide reactive oxygen species respectively. Moreover, EPS-NA3 attenuated the formation of Bacillus cereus and Salmonella typhimurium biofilms by inhibition ratios of approximately 80% and 40% respectively. Additionally, treatment with EPS-NA3 dispersed established biofilms of B. cereus and S. typhimurium by approximately 90% and 20% respectively.

Conclusion

These results suggest that EPS-NA3 may be developed as antioxidant and anti-biofilm agents for industrial and clinical applications due to its capacity of scavenging free radicals, inhibition of bacterial biofilm formation, and dispersion of established biofilms.

Mathematical modelling of telomere length dynamics

Telomeres are repetitive DNA sequences located at the ends of chromosomes. During cell division, an incomplete copy of each chromosome's DNA is made, causing telomeres to shorten on successive generations. When a threshold length is reached replication ceases and the cell becomes 'senescent'. In this paper, we consider populations of telomeres and, from discrete models, we derive partial differential equations which describe how the distribution of telomere lengths evolves over many generations. We initially consider a population of cells each containing just a single telomere. We use continuum models to compare the effects of various mechanisms of telomere shortening and rates of cell division during normal ageing. For example, the rate (or probability) of cell replication may be fixed or it may decrease as the telomeres shorten. Furthermore, the length of telomere lost on each replication may be constant, or may decrease as the telomeres shorten. Where possible, explicit solutions for the evolution of the distribution of telomere lengths are presented. In other cases, expressions for the mean of the distribution are derived. We extend the models to describe cell populations in which each cell contains a distinct subpopulation of chromosomes. As for the simpler models, constant telomere shortening leads to a linear reduction in telomere length over time, whereas length-dependent shortening results in initially rapid telomere length reduction, slowing at later times. Our analysis also reveals that constant telomere loss leads to a Gaussian (normal) distribution of telomere lengths, whereas length-dependent loss leads to a log-normal distribution. We show that stochastic models, which include a replication probability, also lead to telomere length distributions which are skewed.

The Polycomb Protein Bmi1 Plays a Crucial Role in the Prevention of 1,25(OH)2 D Deficiency-Induced Bone Loss

We analyzed the skeletal phenotypes of heterozygous null Cyp27b1 (Cyp27b1^+/- ) mice and their wild-type (WT) littermates to determine whether haploinsufficiency of Cyp27b1 accelerated bone loss, and to examine potential mechanisms of such loss. We found that serum 1,25-dihydroxyvitamin D [1,25(OH)₂ D] levels were significantly decreased in aging Cyp27b1^+/- mice, which displayed an osteoporotic phenotype. This was accompanied by a reduction of expression of the B lymphoma Moloney murine leukemia virus (Mo-MLV) insertion region 1 (Bmi1) at both gene and protein levels. Using chromatin immunoprecipitation (ChIP)-PCR, electrophoretic mobility shift assay (EMSA) and a luciferase reporter assay, we then showed that 1,25(OH)₂ D₃ upregulated Bmi1 expression at a transcriptional level via the vitamin D receptor (VDR). To determine whether Bmi1 overexpression in mesenchymal stem cells (MSCs) could correct bone loss induced by 1,25(OH)₂ D deficiency, we overexpressed Bmi1 in MSCs using Prx1-driven Bmi1 transgenic mice (Bmi1^Tg ) mice. We then compared the bone phenotypes of Bmi1^Tg mice on a Cyp27b1^+/- background, with those of Cyp27b1^+/- mice and with those of WT mice, all at 8 months of age. We found that overexpression of Bmi1 in MSCs corrected the bone phenotype of Cyp27b1^+/- mice by increasing osteoblastic bone formation, reducing osteoclastic bone resorption, increasing bone volume, and increasing bone mineral density. Bmi1 overexpression in MSCs also corrected 1,25(OH)₂ D deficiency-induced oxidative stress and DNA damage, and cellular senescence of Cyp27b1^+/- mice by reducing levels of reactive oxygen species (ROS), elevating serum total superoxide dismutase levels, reducing the percentage of γH₂ A.X, p16, IL-1β, and TNF-α-positive cells and decreasing γH2A.X, p16, p19, p53, p21, IL-1β, and IL-6 expression levels. Furthermore, 1,25(OH)₂ D stimulated the osteogenic differentiation of MSCs, both ex vivo and in vitro, from WT mice but not from Bmi1^-/- mice and 1,25(OH)₂ D administration in vivo increased osteoblastic bone formation in WT, but not in Bmi1 ^-/- mice. Our results indicate that Bmi1, a key downstream target of 1,25(OH)₂ D, plays a crucial role in preventing bone loss induced by 1,25(OH)₂ D deficiency. © 2019 American Society for Bone and Mineral Research.

Combination of Lutein and Zeaxanthin, and DHA Regulated Polyunsaturated Fatty Acid Oxidation in H2O2-Stressed Retinal Cells

Photochemical and oxidative damages in retinal pigment epithelial (RPE) cells are key events in the pathogenesis of age-related macular degeneration. Polyunsaturated fatty acids (PUFA) and carotenoids are rich in retinal cells, and under oxidative stress leads to oxidation and release lipid mediators. We evaluated the impact of carotenoids (lutein, zeaxanthin) and docosahexaenoic acid (DHA) supplementation on RPE cells under oxidative stress. ARPE-19 cells were exposed to H₂O₂ after pre-treatment with lutein, zeaxanthin, DHA, lutein + zeaxanthin or lutein + zeaxanthin with DHA. The data showed H₂O₂ reduced cell viability and DHA content, while promoted catalase activity and certain oxidized PUFA products. Treatment with DHA enhanced omega-3 PUFA enzymatic oxidation namely, anti-inflammatory mediators such as hydroxy-DHA, resolvins and neuroprotection compared to control; the effects were not influenced by the carotenoids. Omega-6 PUFA oxidation, namely pro-inflammatory HETE (5-, 9-, 12 and 20-HETE), and isoprostanes (5- and 15-F_2t-IsoP and 4-F_3t-IsoP) were reduced by lutein + zeaxanthin while the addition of DHA did not further reduce these effects. We observed transcriptional regulation of 5-lipoxygenase by DHA and GPx1 and NEFEL2 by the carotenoids that potentially resulted in decreased HETEs and glutathione respectively. 4-HNE was not affected by the treatments but 4-HHE was reduced by lutein + zeaxanthin with and without DHA. To conclude, carotenoids and DHA appeared to regulate inflammatory lipid mediators while the carotenoids also showed benefits in reducing non-enzymatic oxidation of omega-6 PUFA.

Implications of Oxidative Stress and Cellular Senescence in Age-Related Thymus Involution

The human thymus is a primary lymphoepithelial organ which supports the production of self-tolerant T cells with competent and regulatory functions. Paradoxically, despite the crucial role that it exerts in T cell-mediated immunity and prevention of systemic autoimmunity, the thymus is the first organ of the body that exhibits age-associated degeneration/regression, termed “thymic involution.” A hallmark of this early phenomenon is a progressive decline of thymic mass as well as a decreased output of naïve T cells, thus resulting in impaired immune response. Importantly, thymic involution has been recently linked with cellular senescence which is a stress response induced by various stimuli. Accumulation of senescent cells in tissues has been implicated in aging and a plethora of age-related diseases. In addition, several lines of evidence indicate that oxidative stress, a well-established trigger of senescence, is also involved in thymic involution, thus highlighting a possible interplay between oxidative stress, senescence, and thymic involution.

Genetic Dissection of Alzheimer's Disease Using Drosophila Models

Alzheimer’s disease (AD), a main cause of dementia, is the most common neurodegenerative disease that is related to abnormal accumulation of the amyloid β (Aβ) protein. Despite decades of intensive research, the mechanisms underlying AD remain elusive, and the only available treatment remains symptomatic. Molecular understanding of the pathogenesis and progression of AD is necessary to develop disease-modifying treatment. Drosophila, as the most advanced genetic model, has been used to explore the molecular mechanisms of AD in the last few decades. Here, we introduce Drosophila AD models based on human Aβ and summarize the results of their genetic dissection. We also discuss the utility of functional genomics using the Drosophila system in the search for AD-associated molecular mechanisms in the post-genomic era.

A designed second-sphere hydrogen-bond interaction that critically influences the O-O bond activation for heterolytic cleavage in ferric iron-porphyrin complexes

Heme hydroperoxidases catalyze the oxidation of substrates by H2O2. The catalytic cycle involves the formation of a highly oxidizing species known as Compound I, resulting from the two-electron oxidation of the ferric heme in the active site of the resting enzyme. This high-valent intermediate is formed upon facile heterolysis of the O-O bond in the initial FeIII-OOH complex. Heterolysis is assisted by the histidine and arginine residues present in the heme distal cavity. This chemistry has not been successfully modeled in synthetic systems up to now. In this work, we have used a series of iron(iii) porphyrin complexes (FeIIIL2(Br), FeIIIL3(Br) and FeIIIMPh(Br)) with covalently attached pendent basic groups (pyridine and primary amine) mimicking the histidine and arginine residues in the distal-pocket of natural heme enzymes. The presence of pendent basic groups, capable of 2nd sphere hydrogen bonding interactions, leads to almost 1000-fold enhancement in the rate of Compound I formation from peracids relative to analogous complexes without these residues. The short-lived Compound I intermediate formed at cryogenic temperatures could be detected using UV-vis electronic absorption spectroscopy and also trapped to be unequivocally identified by 9 GHz EPR spectroscopy at 4 K. The broad (2000 G) and axial EPR spectrum of an exchange-coupled oxoferryl-porphyrin radical species, [FeIV[double bond, length as m-dash]O Por˙+] with g eff ⊥ = 3.80 and g eff ‖ = 1.99, was observed upon a reaction of the FeIIIL3(Br) porphyrin complex with m-CPBA. The characterization of the reactivity of the FeIII porphyrin complexes with a substrate in the presence of an oxidant like m-CPBA by UV-vis electronic absorption spectroscopy showed that they are capable of oxidizing two equivalents of inorganic and organic substrate(s) like ferrocene, 2,4,6-tritertiary butyl phenol and o-phenylenediamine. These oxidations are catalytic with a turnover number (TON) as high as 350. Density Functional Theory (DFT) calculations show that the mechanism of O-O bond activation by 2nd sphere hydrogen bonding interaction from these pendent basic groups, which are protonated by a peracid, involves polarization of the O-O σ-bond, leading to lowering of the O-O σ*-orbital allowing enhanced back bonding from the iron center. These results demonstrate how inclusion of 2nd sphere hydrogen bonding interaction can play a critical role in O-O bond heterolysis.

Cysteine Toxicity Drives Age-Related Mitochondrial Decline by Altering Iron Homeostasis

Mitochondria and lysosomes are functionally linked, and their interdependent decline is a hallmark of aging and disease. Despite the long-standing connection between these organelles, the function(s) of lysosomes required to sustain mitochondrial health remains unclear. Here, working in yeast, we show that the lysosome-like vacuole maintains mitochondrial respiration by spatially compartmentalizing amino acids. Defects in vacuole function result in a breakdown in intracellular amino acid homeostasis, which drives age-related mitochondrial decline. Among amino acids, we find that cysteine is most toxic for mitochondria and show that elevated non-vacuolar cysteine impairs mitochondrial respiration by limiting intracellular iron availability through an oxidant-based mechanism. Cysteine depletion or iron supplementation restores mitochondrial health in vacuole-impaired cells and prevents mitochondrial decline during aging. These results demonstrate that cysteine toxicity is a major driver of age-related mitochondrial deterioration and identify vacuolar amino acid compartmentation as a cellular strategy to minimize amino acid toxicity.

The Roles of FoxO Transcription Factors in Regulation of Bone Cells Function

Forkhead box class O family member proteins (FoxOs) are evolutionarily conserved transcription factors for their highly conserved DNA-binding domain. In mammalian species, all the four FoxO members, FoxO1, FoxO3, FoxO4, and FoxO6, are expressed in different organs. In bone, the first three members are extensively expressed and more studied. Bone development, remodeling, and homeostasis are all regulated by multiple cell lineages, including osteoprogenitor cells, chondrocytes, osteoblasts, osteocytes, osteoclast progenitors, osteoclasts, and the intercellular signaling among these bone cells. The disordered FoxOs function in these bone cells contribute to osteoarthritis, osteoporosis, or other bone diseases. Here, we review the current literature of FoxOs for their roles in bone cells, focusing on helping researchers to develop new therapeutic approaches and prevent or treat the related bone diseases.

Hydroxycinnamyl Derived BODIPY as a Lipophilic Fluorescence Probe for Peroxyl Radicals

Herein, we describe the synthesis of a fluorescent probe NB-2 and its use for the detection of peroxyl radicals. This probe is composed of two receptor segments (4-hydroxycinnamyl moieties) sensitive towards peroxyl radicals that are conjugated with a fluorescent reporter, dipyrrometheneboron difluoride (BODIPY), whose emission changes depend on the oxidation state of the receptors. The measurement of the rate of peroxidation of methyl linoleate in a micellar system in the presence of 1.0 µM NB-2 confirmed its ability to trap lipid peroxyl radicals with the rate constant k_inh = 1000 M⁻¹·s⁻¹, which is ten-fold smaller than for pentamethylchromanol (an analog of α-tocopherol). The reaction of NB-2 with peroxyl radicals was further studied via fluorescence measurements in methanol, with α,α′-azobisisobutyronitrile (AIBN) used as a source of radicals generated by photolysis or thermolysis, and in the micellar system at pH 7.4, with 2,2′-azobis(2-amidinopropane) (ABAP) used as a thermal source of the radicals. The reaction of NB-2 receptors with peroxyl radicals manifests itself by the strong increase of a fluorescence with a maximum at 612–616 nm, with a 14-fold enhancement of emission in methanol and a 4-fold enhancement in the micelles, as compared to the unoxidized probe. Our preliminary results indicate that NB-2 behaves as a “switch on” fluorescent probe that is suitable for sensing peroxyl radicals in an organic lipid environment and in bi-phasic dispersed lipid systems.

Ageing, age-related diseases and oxidative stress: What to do next?

Among other mechanisms, oxidative stress has been postulated to play an important role in the rate of ageing. Oxidative damage contributes to the hallmarks of ageing and essential components in pathological pathways which are thought to drive multiple age-related diseases. Nonetheless, results from studies testing the hypothesis of oxidative stress in ageing and diseases showed controversial results. While observational studies mainly found detrimental effects of high oxidative stress levels on disease status, randomized clinical trials examining the effect of antioxidant supplementation on disease status generally showed null effects. However, re-evaluations of these counterinitiative observations are required considering the lack of reliability and specificity of traditionally used biomarkers for measuring oxidative stress. To facilitate these re-evaluations, this review summarizes the basic knowledge of oxidative stress and the present findings regarding the role of oxidative damage in ageing and age-related diseases. Meanwhile, two approaches are highlighted, namely proper participants selection, together with the development of reliable biomarkers. We propose that oxidized vitamin E metabolites may be used to accurately monitor individual functional antioxidant level, which might serve as promising key solutions for future elucidating the impact of oxidative stress on ageing and age-related diseases.

Oxidative Stress, Frailty and Cardiovascular Diseases: Current Evidence

The aim of this chapter is to review the results of recent studies analyzing the role of oxidative stress and systemic inflammation as potential contributors to frailty and CVD, and to explain a possible pathogenic relationship between the latter two conditions. Available evidence suggests that frail patients have elevated levels of oxidative stress biomarkers and proinflammatory cytokines, as well as with reduced concentrations of endogenous antioxidants. This implies that oxidative stress and systemic inflammation might play a role in the pathogenesis of frailty, but an underlying mechanism of this relationship is still mostly hypothetical. Oxidative stress and systemic inflammation are also involved in the pathogenesis of CVD. Cardiovascular conditions are established risk factor for frailty and in turn, presence of frailty constitutes an unfavorable prognostic factor in cardiac patients. Finally, some cardiovascular risk factors, such as lack of physical activity, smoking, obesity and inappropriate diet, are also involved in the etiology of oxidative stress, chronic inflammation and frailty. This complex interplay between intrinsic and extrinsic elements should be considered during holistic management of older persons with frailty and/or cardiovascular conditions.

Alpha-mangostin decreased cellular senescence in human umbilical vein endothelial cells

BACKGROUND

The hyperglycemic condition in diabetes induces cellular senescence in vascular endothelial cells and causes cardiovascular complications. Alpha-mangostin is a xanthone found in Garcinia mangostana, and has shown protective effects in metabolic syndrome.

OBJECTIVE

In this study, the anti-senescence effects of alpha-mangostin in the hyperglycemic condition are investigated.

METHODS

HUVECs were incubated with high glucose for 6 days and co-treated by metformin or alpha-mangostin. After 6 days, cell viability, reactive oxygen species, the percentage of senescent cells, secretory interleukin-6, and the expression of SIRT1, AMPK, p53 and p21 were measured.

RESULTS

High glucose (60 mM) significantly decreased cellular viability and increased reactive oxygen species and cellular senescence through the reduction of senescence-associated β-galactosidase activity. Moreover, high glucose increased the protein levels of p53, acetyl-p53 and p21. The protein levels of SIRT1 and total AMPK were decreased by high glucose. High glucose increased the secretion of IL-6. Alpha-mangostin (1.25 μM) and metformin (50 μM) reversed the toxic effects of high glucose in HUVECs.

CONCLUSION

These results show that alpha-mangostin, similar to metformin, has anti-senescence effects in high-glucose conditions, which is probably due to its antioxidant activity through the SIRT1 pathway. Alpha-mangostin has previously shown anti-inflammatory effects and metabolic status improvement in animal and clinical studies. Therefore, this natural agent can be considered as a supplement to prevent vascular complications caused by high glucose in patients with diabetes. Graphical abstract.

DNA damage in human skin and the capacities of natural compounds to modulate the bystander signalling

Human skin is a stratified organ frequently exposed to sun-generated ultraviolet radiation (UVR), which is considered one of the major factors responsible for DNA damage. Such damage can be direct, through interactions of DNA with UV photons, or indirect, mainly through enhanced production of reactive oxygen species that introduce oxidative changes to the DNA. Oxidative stress and DNA damage also associate with profound changes at the cellular and molecular level involving several cell cycle and signal transduction factors responsible for DNA repair or irreversible changes linked to ageing. Crucially, some of these factors constitute part of the signalling known for the induction of biological changes in non-irradiated, neighbouring cells and defined as the bystander effect. Network interactions with a number of natural compounds, based on their known activity towards these biomarkers in the skin, reveal the capacity to inhibit both the bystander signalling and cell cycle/DNA damage molecules while increasing expression of the anti-oxidant enzymes. Based on this information, we discuss the likely polypharmacology applications of the natural compounds and next-generation screening technologies in improving the anti-oxidant and DNA repair capacities of the skin.

Increase in omega-6 and decrease in omega-3 polyunsaturated fatty acid oxidation elevates the risk of exudative AMD development in adults with Chinese diet

Appropriate diet is essential for the regulation of age-related macular degeneration (AMD). In particular the type of dietary polyunsaturated fatty acids (PUFA) and poor antioxidant status including carotenoid levels concomitantly contribute to AMD risk. Build-up of oxidative stress in AMD induces PUFA oxidation, and a mix of lipid oxidation products (LOPs) are generated. However, LOPs are not comprehensively evaluated in AMD. LOPs are considered biomarkers of oxidative stress but also contributes to inflammatory response. In this cross-sectional case-control study, plasma omega-6/omega-3 PUFA ratios and antioxidant status (glutathione, superoxide dismutase and catalase), and plasma and urinary LOPs (41 types) were determined to evaluate its odds-ratio in the risk of developing exudative AMD (n = 99) compared to age-gender-matched healthy controls (n = 198) in adults with Chinese diet. The odds ratio of developing exudative AMD increased with LOPs from omega-6 PUFA and decreased from those of omega-3 PUFA. These observations were associated with a high plasma omega-6/omega-3 PUFA ratio and low carotenoid levels. In short, poor PUFA and antioxidant status increased the production of omega-6 PUFA LOPs such as dihomo-isoprostane and dihomo-isofuran, and lowered omega-3 PUFA LOPs such as neuroprostanes due to the high omega-6/omega-3 PUFA ratios; they were also correlated to the risk of AMD development. These findings indicate the generation of specific LOPs is associated with the development of exudative AMD.

Exogenous Melatonin Delays Methyl Jasmonate-Triggered Senescence in Tomato Leaves

Leaf senescence represents the last stage of leaf development and is highly regulated by plant hormones and environmental factors. Leaf senescence limits growth and yields in crops, leading to a significant portion of agricultural loss. It is thus crucial to develop strategies to delay this physiological process. Melatonin, an extensively studied molecule, has been demonstrated to play a role in the regulation of leaf senescence in plants. Here, we report the role of exogenous melatonin in the alleviation of methyl jasmonate (MeJA)-induced senescence in tomato (Solanum lycopersicum) leaves. The application of melatonin led to slower degradation of chlorophyll, reduced electrolyte leakage, decreased malondialdehyde (MDA) content, and reduced reactive oxygen species (ROS) levels in tomato leaves incubated with MeJA. In addition, melatonin repressed the upregulation of senescence-related genes (SAG and SEN) and chlorophyll degradation genes (SGR1 and PAO) in tomato leaves exposed to MeJA. Furthermore, melatonin stimulated the activity of a Calvin-Benson Cycle enzyme sedoheptulose-1,7-bisphosphatase (SBPase) and alleviated the inhibition of SlSBPASE (tomato SBPase gene) expression and in MeJA-treated tomato leaves, suggesting an action of melatonin on the capacity for carbon fixation during senescence. Collectively, these results support a role for melatonin in the alleviation of MeJA-induced senescence in tomato leaves. This work also presents a case study that melatonin may be a useful agent in the delay of crop senescence in agricultural practice.

Astaxanthin: A Potential Mitochondrial-Targeted Antioxidant Treatment in Diseases and with Aging

Oxidative stress is characterized by an imbalance between prooxidant and antioxidant species, leading to macromolecular damage and disruption of redox signaling and cellular control. It is a hallmark of various diseases including metabolic syndrome, chronic fatigue syndrome, neurodegenerative, cardiovascular, inflammatory, and age-related diseases. Several mitochondrial defects have been considered to contribute to the development of oxidative stress and known as the major mediators of the aging process and subsequent age-associated diseases. Thus, mitochondrial-targeted antioxidants should prevent or slow down these processes and prolong longevity. This is the reason why antioxidant treatments are extensively studied and newer and newer compounds with such an effect appear. Astaxanthin, a xanthophyll carotenoid, is the most abundant carotenoid in marine organisms and is one of the most powerful natural compounds with remarkable antioxidant activity. Here, we summarize its antioxidant targets, effects, and benefits in diseases and with aging.