Oxyl radicals, redox-sensitive signalling cascades and antioxidants

Melatonin: A Versatile Protector against Oxidative DNA Damage

Oxidative damage to DNA has important implications for human health and has been identified as a key factor in the onset and development of numerous diseases. Thus, it is evident that preventing DNA from oxidative damage is crucial for humans and for any living organism. Melatonin is an astonishingly versatile molecule in this context. It can offer both direct and indirect protection against a wide variety of damaging agents and through multiple pathways, which may (or may not) take place simultaneously. They include direct antioxidative protection, which is mediated by melatonin's free radical scavenging activity, and also indirect ways of action. The latter include, at least: (i) inhibition of metal-induced DNA damage; (ii) protection against non-radical triggers of oxidative DNA damage; (iii) continuous protection after being metabolized; (iv) activation of antioxidative enzymes; (v) inhibition of pro-oxidative enzymes; and (vi) boosting of the DNA repair machinery. The rather unique capability of melatonin to exhibit multiple neutralizing actions against diverse threatening factors, together with its low toxicity and its ability to cross biological barriers, are all significant to its efficiency for preventing oxidative damage to DNA.

Role of Oxidative Stress as Key Regulator of Muscle Wasting during Cachexia

Skeletal muscle atrophy is a pathological condition mainly characterized by a loss of muscular mass and the contractile capacity of the skeletal muscle as a consequence of muscular weakness and decreased force generation. Cachexia is defined as a pathological condition secondary to illness characterized by the progressive loss of muscle mass with or without loss of fat mass and with concomitant diminution of muscle strength. The molecular mechanisms involved in cachexia include oxidative stress, protein synthesis/degradation imbalance, autophagy deregulation, increased myonuclear apoptosis, and mitochondrial dysfunction. Oxidative stress is one of the most common mechanisms of cachexia caused by different factors. It results in increased ROS levels, increased oxidation-dependent protein modification, and decreased antioxidant system functions. In this review, we will describe the importance of oxidative stress in skeletal muscles, its sources, and how it can regulate protein synthesis/degradation imbalance, autophagy deregulation, increased myonuclear apoptosis, and mitochondrial dysfunction involved in cachexia.

Oxidant-Antioxidant Balance in the Aqueous Humor of Patients with Retinal Vein Occlusion

PURPOSE

To analyze oxidative stress parameters in the aqueous humor with retinal vein occlusion.

MATERIALS AND METHODS

A total of 56 patients who underwent cataract surgery were enrolled in this study. The eyes with retinal vein occlusion were included in the study group. Aqueous humor was sampled from all patients and analyzed by an automated measurement method. Total oxidant status (TOS), total antioxidant status (TAS), and oxidative stres index (OSI) were calculated.

RESULTS

OSI was significantly higher in the study group (p = 0.04). TAS was significantly lower (p = 0.01) and OSI was significantly higher (p = 0.01) in cases with both central retinal vein occlusion and macular edema. Previous laser photocoalugation to the retina and the duration of disease had no significant effect on the levels of oxidative stress parameters.

CONCLUSION

OSI was found higher in patients with retinal vein occlusion. This increase is more significant in patients with macular edema and central retinal vein occlusion; in which TAS was also found to decrease.

Antioxidants as precision weapons in war against cancer chemotherapy induced toxicity - Exploring the armoury of obscurity

Cancer is the leading cause of mortality worldwide, accounting for almost 13% of deaths in the world. Among the conventional cancer treatments, chemotherapy is most frequently carried out to treat malignant cancer rather than localised lesions which is amenable to surgery and radiotherapy. However, anticancer drugs are associated with a plethora of side effects. Each drug, within every class, has its own set of adverse reactions which may cause patient incompliance and deterioration of the quality of life. One of the major causes of adverse reactions, especially for drugs targeting DNA, is the excessive production of reactive oxygen species (ROS) and subsequent build up of oxidative stress. To curb these undesired side effects, several dietary supplements have been tested, amongst which antioxidants have gained increasing popularity as adjuvant in chemotherapy. However, many oncologists discourage the use of antioxidant rich food supplements because these may interfere with the modalities which kill cancer by generating free radicals. In the present review, all studies reporting concomitant use of several antioxidants with chemotherapy are indiscriminately included and discussed impartially.

The effect of supplementation of thirteen different antioxidants and their analogues as a single agent or in combination with chemotherapy has been compiled in this article. The present review encompasses a total of 174 peer-reviewed original articles from 1967 till date comprising 93 clinical trials with a cumulative number of 18,208 patients, 56 animal studies and 35 in vitro studies. Our comprehensive data suggests that antioxidant has superior potential of ameliorating chemotherapeutic induced toxicity. Antioxidant supplementation during chemotherapy also promises higher therapeutic efficiency and increased survival times in patients.

The antihypertensive drug hydralazine activates the intrinsic pathway of apoptosis and causes DNA damage in leukemic T cells

Epigenetic therapies have emerged as promising anticancer approaches, since epigenetic modifications play a major role in tumor initiation and progression. Hydralazine, an approved vasodilator and antihypertensive drug, has been recently shown to act as a DNA methylation inhibitor. Even though hydralazine is already tested in clinical cancer trials, its mechanism of antitumor action remains undefined. Here, we show that hydralazine induced caspase-dependent apoptotic cell death in human p53-mutant leukemic T cells. Moreover, we demonstrate that hydralazine triggered the mitochondrial pathway of apoptosis by inducing Bak activation and loss of the mitochondrial membrane potential. Hydralazine treatment further resulted in the accumulation of reactive oxygen species, whereas a superoxide dismutase mimetic inhibited hydralazine-induced cell death. Interestingly, caspase-9-deficient Jurkat cells or Bcl-2- and Bcl-x_L-overexpressing cells were strongly resistant to hydralazine treatment, thereby demonstrating the dependence of hydralazine-induced apoptosis on the mitochondrial death pathway. Furthermore, we demonstrate that hydralazine treatment triggered DNA damage which might contribute to its antitumor effect.

IL-1β haplotype influences the effect of NOx exposure on gestational age in the South African MACE birth cohort

OBJECTIVE

Cytokines, molecules within the immune system that affect either a pro- or anti-inflammatory response, have previously been shown to influence birth outcomes. The maternal cytokine gene-environment interactions are thought to alter their expression, potentially influencing susceptibility to adverse birth outcomes. The aim of this study was to determine the association between the maternal interleukin-1β (IL-1β) haplotype and expression variation with oxides of nitrogen (NO_x) levels, and thereafter investigate the IL-1β haplotype-specific effects of NO_x exposure levels, IL-1β mRNA expression and other variables on gestational age.

MATERIAL AND METHODS

Using the prospective Mother and Child in the Environment (MACE) birth cohort in Durban, South Africa, 335 participants were genotyped for the IL-1β haplotype. Previous studies showed that three single nucleotide polymorphisms (SNPs), IL-1β-1464G/C, -511C/T and -31C/T, constitute the IL-1β functional haplotype. These SNPs were genotyped using a restriction fragment length polymorphism assay, while IL-1β mRNA expression was measured using a quantitative real-time polymerase chain reaction assay. Individual estimates of NO_x exposure were obtained by land use regression modelling. A multivariate linear regression analysis was employed to test for significant effects on gestational age.

RESULTS

IL-1β mRNA expression was found to possess a haplotype-dependent effect ( p = 0.0001) and its expression levels positively correlated with NO_x levels ( r = 0.34; p = 0.006). In the high haplotype model, a unit increase in NO_x exposure level was associated with a decrease in gestational age by 1 week ( p = 0.02). Furthermore, gestational age decreased by 0.9 weeks for every unit increase of IL-1β mRNA expression level ( p = 0.025). HIV-1 positivity was associated with a 0.2-week decrease in gestational age ( p = 0.035) in the intermediate haplotype model and a 0.4-week decrease in the high haplotype model ( p = 0.044).

CONCLUSION

These data have implications for better understanding the effect of prenatal NO_x exposure on gestational age and demonstrate the role of the IL-1β haplotype in modulating the effects of NO_x exposure.

Treatment with a JNK inhibitor increases, whereas treatment with a p38 inhibitor decreases, H2O2-induced calf pulmonary arterial endothelial cell death

Oxidative stress induces apoptosis in endothelial cells (ECs). Reactive oxygen species (ROS) promote cell death by regulating the activity of various mitogen-activated protein kinases (MAPKs) in ECs. The present study investigated the effects of MAPK inhibitors on cell survival and glutathione (GSH) levels upon H₂O₂ treatment in calf pulmonary artery ECs (CPAECs). H₂O₂ treatment inhibited the growth and induced the death of CPAECs, as well as causing GSH depletion and the loss of mitochondrial membrane potential (MMP). While treatment with the MEK or JNK inhibitor impaired the growth of H₂O₂-treated CPAECs, treatment with the p38 inhibitor attenuated this inhibition of growth. Additionally, JNK inhibitor treatment increased the proportion of sub-G₁ phase cells in H₂O₂-treated CPAECs and further decreased the MMP. However, treatment with a p38 inhibitor reversed the effects of H₂O₂ treatment on cell growth and the MMP. Similarly, JNK inhibitor treatment further increased, whereas p38 inhibitor treatment decreased, the proportion of GSH-depleted cells in H₂O₂-treated CPAECs. Each of the MAPK inhibitors affected cell survival, and ROS or GSH levels differently in H₂O₂-untreated, control CPAECs. The data suggest that the exposure of CPAECs to H₂O₂ caused the cell growth inhibition and cell death through GSH depletion. Furthermore, JNK inhibitor treatment further enhanced, whereas p38 inhibitors attenuated, these effects. Thus, the results of the present study suggest a specific protective role for the p38 inhibitor, and not the JNK inhibitor, against H₂O₂-induced cell growth inhibition and cell death.

Prevalence of exposure of heavy metals and their impact on health consequences

Even in the current era of growing technology, the concentration of heavy metals present in drinking water is still not within the recommended limits as set by the regulatory authorities in different countries of the world. Drinking water contaminated with heavy metals namely; arsenic, cadmium, nickel, mercury, chromium, zinc, and lead is becoming a major health concern for public and health care professionals. Occupational exposure to heavy metals is known to occur by the utilization of these metals in various industrial processes and/or contents including color pigments and alloys. However, the predominant source resulting in measurable human exposure to heavy metals is the consumption of contaminated drinking water and the resulting health issues may include cardiovascular disorders, neuronal damage, renal injuries, and risk of cancer and diabetes. The general mechanism involved in heavy metal-induced toxicity is recognized to be the production of reactive oxygen species resulting oxidative damage and health related adverse effects. Thus utilization of heavy metal-contaminated water is resulting in high morbidity and mortality rates all over the world. Thereby, feeling the need to raise the concerns about contribution of different heavy metals in various health related issues, this article has discussed the global contamination of drinking water with heavy metals to assess the health hazards associated with consumption of heavy metal-contaminated water. A relationship between exposure limits and ultimate responses produced as well as the major organs affected have been reviewed. Acute and chronic poisoning symptoms and mechanisms responsible for such toxicities have also been discussed.

A Graphene Quantum Dots-Hypochlorite Hybrid System for the Quantitative Fluorescent Determination of Total Antioxidant Capacity

Antioxidants play a major part in the prevention and impairment of oxidative stress-induced damages and diseases. Evaluating the antioxidants activity/capacity in food and biological fluid is proved to be useful for the diagnosis and treatment of these oxidative stress-induced diseases. Herein, a graphene quantum dots (GQDs)-hypochlorite system to detect the antioxidants including nonenzymatic and enzymatic antioxidants in the biological fluid is proposed. The detection principle is based on the fact that antioxidants can protect the fluorescence of GQDs from hypochlorite-caused quenching by acting as the scavengers of hypochlorite. The GQDs-hypochlorite system allows the accurate quantification of the total antioxidant capacity (TAC) of commercial drinks as well as the extracellular superoxide dismutase (SOD) secretion upon stimulation of cytokines or hyperglycemia. This system shows the excellent analytical recoveries for commercial drinks (>89.9%) and good consistency with ELISA testing for SOD secretion in cell-conditioned medium. These results demonstrate the ability and reliability of the GQD-hypochlorite system for detecting and quantifying TAC in real drinks and complex biological fluids.

Oxidative Stress: Harms and Benefits for Human Health

Oxidative stress is a phenomenon caused by an imbalance between production and accumulation of oxygen reactive species (ROS) in cells and tissues and the ability of a biological system to detoxify these reactive products. ROS can play, and in fact they do it, several physiological roles (i.e., cell signaling), and they are normally generated as by-products of oxygen metabolism; despite this, environmental stressors (i.e., UV, ionizing radiations, pollutants, and heavy metals) and xenobiotics (i.e., antiblastic drugs) contribute to greatly increase ROS production, therefore causing the imbalance that leads to cell and tissue damage (oxidative stress). Several antioxidants have been exploited in recent years for their actual or supposed beneficial effect against oxidative stress, such as vitamin E, flavonoids, and polyphenols. While we tend to describe oxidative stress just as harmful for human body, it is true as well that it is exploited as a therapeutic approach to treat clinical conditions such as cancer, with a certain degree of clinical success. In this review, we will describe the most recent findings in the oxidative stress field, highlighting both its bad and good sides for human health.

Effects of folic acid on rat kidney exposed to 900 MHz electromagnetic radiation

Because of increased use of cell phones, the purpose of this study was to investigation of the oxidative damage caused by electromagnetic radiation (EMR) emitted by cell phones and histological and morphometrical determination of the possible protective role of folic acid (FA) in preventing the detrimental effects of EMR on the kidney. Twenty-four adult male Wistar albino rats were divided into control (Cont), EMR, EMR + FA and FA groups, each containing six rats. The EMR and EMR + FA groups were exposed to EMR for 60 min a day over a period of 21 days, while no EMR exposure was applied to the Cont and FA groups. The source of the EMR was an EMR device which emits a digital signal producing 900-MHz frequency radiation. The generator connected to a one-monopole antenna was used in this study and the rats were placed in the plexiglass restrainer at an equal distance from the monopole antenna. Following the experimental period, and after tissue processing, a physical disector-Cavalieri method combination was applied to the sections. The mean volume of the cortex, medulla, proximal and distal tubules increased significantly in the EMR groups compared to the Cont group (p < 0.01). Contrarily, the total number of glomeruli in the EMR group decreased compared to the Cont group (p < 0.01). The protective effects of FA was observed in the kidney (p < 0.05).

In conclusion, the 900-MHz EMR leads to kidney damage. FA may exhibit a protective effect against the adverse effects of EMR exposure in terms of the total number of glomeruli.

Effect of Dark Chocolate Extracts on Phorbol 12-Myristate 13-Acetate-Induced Oxidative Burst in Leukocytes Isolated by Normo-Weight and Overweight/Obese Subjects

Oxidative and inflammatory stress represents a major risk factor for cardiovascular disease (CVD) in overweight and obese subjects. Between the different plant foods, chocolate has been shown to decrease CVD risk due to its antioxidant and anti-inflammatory properties. However, as we recently showed in epidemiological studies, meta-analyses, and human trials, dietary antioxidants resulted more effective in subjects characterized by an ongoing oxidative stress, than in healthy people. Aim of this work was to investigate the effect of different concentrations of chocolate phenolic extract (CPE) on in vitro free radical production, stimulated by phorbol 12-myristate 13-acetate (PMA), in leukocytes extracted from blood of normo-weight and overweight/obese subjects. Neutrophils from overweight/obese group had a significantly higher free radical production compared to the normo-weight group. In neutrophils, the lowest CPE concentration significantly reduced free radical production in overweight/obese group only, and higher CPE concentrations were effective in both groups. In monocytes, the CPE concentration that was significantly effective in reducing free radical production was lower in overweight/obese subjects than in normo-weight subjects. Chocolate polyphenol extracts inhibit oxidative burst in human neutrophils and monocytes with a higher efficiency in subjects characterized by an unphysiological oxidative/inflammatory stress, such as overweight and obese. Results of this study provide further evidence about a differential role of dietary antioxidant strictly related to the “stress” condition of the subjects.

Physiological role of reactive oxygen species as promoters of natural defenses

It has been 60 yr since the discovery of reactive oxygen species (ROS) in biology and the beginning of the scientific community's attempt to understand the impact of the unpaired electron of ROS molecules in biological pathways, which was eventually noted to be toxic. Several studies have shown that the presence of ROS is essential in triggering or acting as a secondary factor for numerous pathologies, including metabolic and genetic diseases; however, it was demonstrated that chronic treatment with antioxidants failed to show efficacy and positive effects in the prevention of diseases or health complications that result from oxidative stress. On the contrary, such treatment has been shown to sometimes even worsen the disease. Because of the permanent presence of ROS in organisms, elaborate mechanisms to adapt with these reactive molecules and to use them without necessarily blocking or preventing their actions have been studied. There is now a large body of evidence that shows that living organisms have conformed to the presence of ROS and, in retrospect, have adapted to the bioactive molecules that are generated by ROS on proteins, lipids, and DNA. In addition, ROS have undergone a shift from being molecules that invoked oxidative damage in regulating signaling pathways that impinged on normal physiological and redox responses. Working in this direction, this review unlocks a new conception about the involvement of cellular oxidants in the maintenance of redox homeostasis in redox regulation of normal physiological functions, and an explanation for its essential role in numerous pathophysiological states is noted.-Roy, J., Galano, J.-M., Durand, T., Le Guennec, J.-Y., Lee, J. C.-Y. Physiological role of reactive oxygen species as promoters of natural defenses.

The Importance of NADPH Oxidases and Redox Signaling in Angiogenesis

Eukaryotic cells have to cope with the constant generation of reactive oxygen species (ROS). Although the excessive production of ROS might be deleterious for cell biology, there is a plethora of evidence showing that moderate levels of ROS are important for the control of cell signaling and gene expression. The family of the nicotinamide adenine dinucleotide phosphate oxidases (NADPH oxidases or Nox) has evolved to produce ROS in response to different signals; therefore, they fulfil a central role in the control of redox signaling. The role of NADPH oxidases in vascular physiology has been a field of intense study over the last two decades. In this review we will briefly analyze how ROS can regulate signaling and gene expression. We will address the implication of NADPH oxidases and redox signaling in angiogenesis, and finally, the therapeutic possibilities derived from this knowledge will be discussed.

Exposure to tetrabromobisphenol A induces cellular dysfunction in osteoblastic MC3T3-E1 cells

This study was undertaken to investigate the possible involvement of oxidative stress in tetrabromobisphenol A (TBBPA)-induced toxicity in osteoblastic MC3T3-E1 cells. To examine the potential effect of TBBPA on cultured osteoblastic cells, we measured cell viability, apoptosis, reactive oxygen species (ROS), mitochondrial superoxide, and mitochondrial parameters including adenosine triphosphate (ATP) level, cardiolipin content, cytochrome c release, cyclophilin levels, and differentiation markers in osteoblastic MC3T3-E1 cells. TBBPA exposure for 48 h caused the apoptosis and cytotoxicity of MC3T3-E1 cells. TBBPA also induced ROS and mitochondrial superoxide production in a concentration-dependent manner. These results suggest that TBBPA induces osteoblast apoptosis and ROS production, resulting in bone diseases. Moreover, TBBPA induced cardiolipin peroxidation, cytochrome c release, and decreased ATP levels which induced apoptosis or necrosis. TBBPA decreased the differentiation markers, collagen synthesis, alkaline phosphatase activity, and calcium deposition in cells. Additionally, TBBPA decreased cyclophilin A and B releases. Taken together, these data support the notion that TBBPA inhibits osteoblast function and has detrimental effects on osteoblasts through a mechanism involving oxidative stress and mitochondrial dysfunction.

Association between lutein intake and lung function in adults: the Rotterdam Study

Lutein, a fat-soluble carotenoid with antioxidant properties, may have an effect on respiratory health. However, the evidence is inconsistent. We aimed to cross-sectionally investigate the association between lutein intake and lung function by measuring forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC% in adults (aged 45-79 years). We included 4402 participants from the Rotterdam Study, a prospective cohort study in The Netherlands. Lutein intake was assessed using a validated FFQ. Lung function was assessed using spirometry around the same time point as the dietary assessment. No independent association was found between lutein intake and FEV1 (-12·17 (95 % CI -34·21, 9·87) ml per sd increase in lutein) after adjustment for age, sex, height, cohort effect, ethnicity, education, weight, total daily energy intake, smoking status, physical activity, and intakes of fatty acids, dietary fibre, alcohol, β-carotene, β-crypotoxanthin, lycopene and zeaxanthin. There was also no association between lutein and FVC or FEV1/FVC%. However, after stratification by smoking status, lutein intake was significantly associated with lower FEV1/FVC% in current smokers (-1·69 (95 % CI -2·93, -0·45) % per sd increase of lutein) independent of other carotenoids. The present study does not support an independent association between lutein intake and lung function in adults. However, future studies should focus on the potential inverse association between high lutein intake and lung function in specific risk groups such as smokers.

Redox control of senescence and age-related disease

The signaling networks that drive the aging process, associated functional deterioration, and pathologies has captured the scientific community's attention for decades. While many theories exist to explain the aging process, the production of reactive oxygen species (ROS) provides a signaling link between engagement of cellular senescence and several age-associated pathologies. Cellular senescence has evolved to restrict tumor progression but the accompanying senescence-associated secretory phenotype (SASP) promotes pathogenic pathways. Here, we review known biological theories of aging and how ROS mechanistically control senescence and the aging process. We also describe the redox-regulated signaling networks controlling the SASP and its important role in driving age-related diseases. Finally, we discuss progress in designing therapeutic strategies that manipulate the cellular redox environment to restrict age-associated pathology.

The Glyoxalase System and Methylglyoxal-Derived Carbonyl Stress in Sepsis: Glycotoxic Aspects of Sepsis Pathophysiology

Sepsis remains one of the leading causes of death in intensive care units. Although sepsis is caused by a viral, fungal or bacterial infection, it is the dysregulated generalized host response that ultimately leads to severe dysfunction of multiple organs and death. The concomitant profound metabolic changes are characterized by hyperglycemia, insulin resistance, and profound transformations of the intracellular energy supply in both peripheral and immune cells. A further hallmark of the early phases of sepsis is a massive formation of reactive oxygen (ROS; e.g., superoxide) as well as nitrogen (RNS; e.g., nitric oxide) species. Reactive carbonyl species (RCS) form a third crucial group of highly reactive metabolites, which until today have been not the focus of interest in sepsis. However, we previously showed in a prospective observational clinical trial that patients suffering from septic shock are characterized by significant methylglyoxal (MG)-derived carbonyl stress, with the glyoxalase system being downregulated in peripheral blood mononuclear cells. In this review, we give a detailed insight into the current state of research regarding the metabolic changes that entail an increased MG-production in septicemia. Thus, we point out the special role of the glyoxalase system in the context of sepsis.

Bioapplications of Electrochemical Sensors and Biosensors

Recent progress in the electrochemical field enabled development of miniaturized sensing devices that can be used in biological settings to obtain fundamental and practical biochemically relevant information on physiology, metabolism, and disease states in living systems. Electrochemical sensors and biosensors have demonstrated potential for rapid, real-time measurements of biologically relevant molecules. This chapter provides an overview of the most recent advances in the development of miniaturized sensors for biological investigations in living systems, with focus on the detection of neurotransmitters and oxidative stress markers. The design of electrochemical (bio)sensors, including their detection mechanism and functionality in biological systems, is described as well as their advantages and limitations. Application of these sensors to studies in live cells, embryonic development, and rodent models is discussed.

Oxidative injury of the pulmonary circulation in the perinatal period: Short- and long-term consequences for the human cardiopulmonary system

Development of the pulmonary circulation is a complex process with a spatial pattern that is tightly controlled. This process is vulnerable for disruption by various events in the prenatal and early postnatal periods. Disruption of normal pulmonary vascular development leads to abnormal structure and function of the lung vasculature, causing neonatal pulmonary vascular diseases. Premature babies are especially at risk of the development of these diseases, including persistent pulmonary hypertension and bronchopulmonary dysplasia. Reactive oxygen species play a key role in the pathogenesis of neonatal pulmonary vascular diseases and can be caused by hyperoxia, mechanical ventilation, hypoxia, and inflammation. Besides the well-established short-term consequences, exposure of the developing lung to injurious stimuli in the perinatal period, including oxidative stress, may also contribute to the development of pulmonary vascular diseases later in life, through so-called "fetal or perinatal programming." Because of these long-term consequences, it is important to develop a follow-up program tailored to adolescent survivors of neonatal pulmonary vascular diseases, aimed at early detection of adult pulmonary vascular diseases, and thereby opening the possibility of early intervention and interfering with disease progression. This review focuses on pathophysiologic events in the perinatal period that have been shown to disrupt human normal pulmonary vascular development, leading to neonatal pulmonary vascular diseases that can extend even into adulthood. This knowledge may be particularly important for ex-premature adults who are at risk of the long-term consequences of pulmonary vascular diseases, thereby contributing disproportionately to the burden of adult cardiovascular disease in the future.

Perfluorooctanoic acid induces mitochondrial dysfunction in MC3T3-E1 osteoblast cells

Perfluorooctanoic acid (PFOA), a stable organic perfluorinated compound, is an emerging persistent organic pollutant, found widely in human and wildlife populations. Recent evidence suggests that exposure to environmental toxicants can be associated with higher risks of osteoporosis and fractures. We studied the cellular toxicology of PFOA in MC3T3-E1osteoblast cells. To examine the effect of PFOA, we measured cell viability, reactive oxygen species (ROS), mitochondrial superoxide, and mitochondrial parameters including adenosine triphosphate (ATP) level, mitochondrial membrane potential (MMP), cardiolipin content, and cytochrome c release in MC3T3-E1 cells. Incubating MC3T3-E1 cells in different concentrations of PFOA for 48 h resulted in a concentration-dependent decrease in cell viability and significant inductions of ROS and mitochondrial superoxide. Moreover, PFOA induced MMP collapse, cardiolipin peroxidation, cytochrome c release, and decreased ATP levels, which in turn induced apoptosis or necrosis. When osteoblast differentiation markers were assessed, PFOA treatment caused a significant reduction in alkaline phosphatase activity, collagen synthesis, and mineralization in the cells. In summary, we found an ROS- and mitochondria-mediated pathway for the induction of cell damage by PFOA in MC3T3-E1 cells. Together, our results indicate that mitochondrial toxicity could be a plausible mechanism for the toxic effects of PFOA on osteoblast function.

Mitochondrial and nuclear DNA dual damage induced by 2-(2′-quinolyl)benzimidazole copper complexes with potential anticancer activity

Complex 2 can induce nuclear and mitochondrial dual damage in HCT116 cells and can also induce apoptosis.

Mechanistic Basis of Antimicrobial Actions of Silver Nanoparticles

Multidrug resistance of the pathogenic microorganisms to the antimicrobial drugs has become a major impediment toward successful diagnosis and management of infectious diseases. Recent advancements in nanotechnology-based medicines have opened new horizons for combating multidrug resistance in microorganisms. In particular, the use of silver nanoparticles (AgNPs) as a potent antibacterial agent has received much attention. The most critical physico-chemical parameters that affect the antimicrobial potential of AgNPs include size, shape, surface charge, concentration and colloidal state. AgNPs exhibits their antimicrobial potential through multifaceted mechanisms. AgNPs adhesion to microbial cells, penetration inside the cells, ROS and free radical generation, and modulation of microbial signal transduction pathways have been recognized as the most prominent modes of antimicrobial action. On the other side, AgNPs exposure to human cells induces cytotoxicity, genotoxicity, and inflammatory response in human cells in a cell-type dependent manner. This has raised concerns regarding use of AgNPs in therapeutics and drug delivery. We have summarized the emerging endeavors that address current challenges in relation to safe use of AgNPs in therapeutics and drug delivery platforms. Based on research done so far, we believe that AgNPs can be engineered so as to increase their efficacy, stability, specificity, biosafety and biocompatibility. In this regard, three perspectives research directions have been suggested that include (1) synthesizing AgNPs with controlled physico-chemical properties, (2) examining microbial development of resistance toward AgNPs, and (3) ascertaining the susceptibility of cytoxicity, genotoxicity, and inflammatory response to human cells upon AgNPs exposure.

Resveratrol, an antioxidant, protects spinal cord injury in rats by suppressing MAPK pathway

Resveratrol, a polyphenol found in various plants, including grapes, plums and peanuts has shown various medIRInal properties, including antioxidant, protection of cardiovascular disease and cancer risk. However, the effects of resveratrol on spinal cord reperfusion injury have not been investigated. Hence, the present study was designed to evaluate the effect of resveratrol on nitric oxide synthase (iNOS)/p38MAPK signaling pathway and to elucidate its regulating effect on the protection of spinal cord injury. Spinal cord ischemia–reperfusion injury (IRI) was performed by the infrarenal abdominal aorta with mini aneurysm clip model. The expressions of iNOS and p38MAPK and the levels of biochemical parameters, including nitrite/nitrate, malondialdehyde (MDA), advanced oxidation products (AOPP), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) were measured in control and experimental groups. IRI-induced rats treated with 10 mg/kg resveratrol protected spinal cord from ischemia injury as supported by improved biological parameters measured in spinal cord tissue homogenates. The resveratrol treatment significantly decreased the levels of plasma nitrite/nitrate, iNOS mRNA and protein expressions and phosphorylation of p38MAPK in IRI-induced rats. Further, IRI-produced free radicals were reduced by resveratrol treatment by increasing enzymatic and non-enzymatic antioxidant levels such as GSH, SOD and CAT. Taken together, administration of resveratrol protects the damage caused by spinal cord ischemia with potential mechanism of suppressing the activation of iNOS/p38MAPK pathway and subsequent reduction of oxidative stress due to IRI.

Astragalus Polysaccharide Suppresses 6-Hydroxydopamine-Induced Neurotoxicity in Caenorhabditis elegans

Astragalus membranaceus is a medicinal plant traditionally used in China for a variety of conditions, including inflammatory and neural diseases. Astragalus polysaccharides are shown to reduce the adverse effect of levodopa which is used to treat Parkinson's disease (PD). However, the neuroprotective effect of Astragalus polysaccharides per se in PD is lacking. Using Caenorhabditis elegans models, we investigated the protective effect of astragalan, an acidic polysaccharide isolated from A. membranaceus, against the neurotoxicity of 6-hydroxydopamine (6-OHDA), a neurotoxin that can induce parkinsonism. We show that 6-OHDA is able to degenerate dopaminergic neurons and lead to the deficiency of food-sensing behavior and a shorter lifespan in C. elegans. Interestingly, these degenerative symptoms can be attenuated by astragalan treatment. Astragalan is also shown to alleviate oxidative stress through reducing reactive oxygen species level and malondialdehyde content and increasing superoxide dismutase and glutathione peroxidase activities and reduce the expression of proapoptotic gene egl-1 in 6-OHDA-intoxicated nematodes. Further studies reveal that astragalan is capable of elevating the decreased acetylcholinesterase activity induced by 6-OHDA. Together, our results demonstrate that the protective effect of astragalan against 6-OHDA neurotoxicity is likely due to the alleviation of oxidative stress and regulation of apoptosis pathway and cholinergic system and thus provide an important insight into the therapeutic potential of Astragalus polysaccharide in neurodegeneration.

Phenolic Melatonin-Related Compounds: Their Role as Chemical Protectors against Oxidative Stress

There is currently no doubt about the serious threat that oxidative stress (OS) poses to human health. Therefore, a crucial strategy to maintain a good health status is to identify molecules capable of offering protection against OS through chemical routes. Based on the known efficiency of the phenolic and melatonin (MLT) families of compounds as antioxidants, it is logical to assume that phenolic MLT-related compounds should be (at least) equally efficient. Unfortunately, they have been less investigated than phenols, MLT and its non-phenolic metabolites in this context. The evidence reviewed here strongly suggests that MLT phenolic derivatives can act as both primary and secondary antioxidants, exerting their protection through diverse chemical routes. They all seem to be better free radical scavengers than MLT and Trolox, while some of them also surpass ascorbic acid and resveratrol. However, there are still many aspects that deserve further investigations for this kind of compounds.

New Insights into the Role of Oxidative Stress Mechanisms in the Pathophysiology and Treatment of Multiple Sclerosis

Multiple sclerosis (MS) is a multifactorial disease of the central nervous system (CNS) characterized by an inflammatory process and demyelination. The etiology of the disease is still not fully understood. Therefore, finding new etiological factors is of such crucial importance. It is suspected that the development of MS may be affected by oxidative stress (OS). In the acute phase OS initiates inflammatory processes and in the chronic phase it sustains neurodegeneration. Redox processes in MS are associated with mitochondrial dysfunction, dysregulation of axonal bioenergetics, iron accumulation in the brain, impaired oxidant/antioxidant balance, and OS memory. The present paper is a review of the current literature about the role of OS in MS and it focuses on all major aspects. The article explains the mechanisms of OS, reports unique biomarkers with regard to their clinical significance, and presents a poorly understood relationship between OS and neurodegeneration. It also provides novel methods of treatment, including the use of antioxidants and the role of antioxidants in neuroprotection. Furthermore, adding new drugs in the treatment of relapse may be useful. The article considers the significance of OS in the current treatment of MS patients.

From DNA damage to functional changes of the trabecular meshwork in aging and glaucoma

Glaucoma is a degenerative disease of the eye. Both the anterior and posterior segments of the eye are affected, extensive damage being detectable in the trabecular meshwork and the inner retina-central visual pathway complex. Oxidative stress is claimed to be mainly responsible for molecular damage in the anterior chamber. Indeed, oxidation harms the trabecular meshwork, leading eventually to endothelial cell decay, tissue malfunction, subclinical inflammation, changes in the extracellular matrix and cytoskeleton, altered motility, reduced outflow facility and (ultimately) increased IOP. Moreover, free radicals are involved in aging and can be produced in the brain (as well as in the eye) as a result of ischemia, leading to oxidation of the surrounding neurons. Glaucoma-related cell death occurs by means of apoptosis, and apoptosis is triggered by oxidative stress via (a) mitochondrial damage, (b) inflammation, (c) endothelial dysregulation and dysfunction, and (d) hypoxia. The proteomics of the aqueous humor is significantly altered in glaucoma as a result of oxidation-induced trabecular damage. Those proteins whose aqueous humor levels are increased in glaucoma are biomarkers of trabecular meshwork impairment. Their diffusion from the anterior to the posterior segment of the eye may be relevant in the cascade of events triggering apoptosis in the inner retinal layers, including the ganglion cells.

The pro-oxidant gene p66shc increases nicotine exposure-induced lipotoxic oxidative stress in renal proximal tubule cells

Nicotine (NIC) exposure augments free fatty acid (FFA) deposition and oxidative stress, with a concomitant increase in the expression of the pro-oxidant p66shc. In addition, a decrease in the antioxidant manganese superoxide dismutase (MnSOD) has been observed in the kidneys of mice fed a high‑fat diet. The present study aimed to determine whether the pro‑oxidant p66shc mediates NIC‑dependent increases in renal oxidative stress by augmenting the production of reactive oxygen species (ROS) and suppressing the FFA‑induced antioxidant response in cultured NRK52E renal proximal tubule cells. Briefly, NRK52E renal proximal tubule cells were treated with 200 µM NIC, 100 µM oleic acid (OA), or a combination of NIC and OA. The expression levels of p66shc and MnSOD were modulated according to genetic methods. ROS production and cell injury, in the form of lactate dehydrogenase release, were subsequently detected. Promoter activity of p66shc and MnSOD, as well as forkhead box (FOXO)‑dependent transcription, was investigated using reporter luciferase assays. The results demonstrated that NIC exacerbated OA‑mediated intracellular ROS production and cell injury through the transcriptional activation of p66shc. NIC also suppressed OA‑mediated induction of the antioxidant MnSOD promoter activity through p66shc‑dependent inactivation of FOXO activity. Overexpression of p66shc and knockdown of MnSOD had the same effect as treatment with NIC on OA‑mediated lipotoxicity. These data may be used to generate a therapeutic means to ameliorate renal lipotoxicity in obese smokers.

Oxidant Mechanisms in Renal Injury and Disease

SIGNIFICANCE

A common link between all forms of acute and chronic kidney injuries, regardless of species, is enhanced generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) during injury/disease progression. While low levels of ROS and RNS are required for prosurvival signaling, cell proliferation and growth, and vasoreactivity regulation, an imbalance of ROS and RNS generation and elimination leads to inflammation, cell death, tissue damage, and disease/injury progression.

RECENT ADVANCES

Many aspects of renal oxidative stress still require investigation, including clarification of the mechanisms which prompt ROS/RNS generation and subsequent renal damage. However, we currently have a basic understanding of the major features of oxidative stress pathology and its link to kidney injury/disease, which this review summarizes.

CRITICAL ISSUES

The review summarizes the critical sources of oxidative stress in the kidney during injury/disease, including generation of ROS and RNS from mitochondria, NADPH oxidase, and inducible nitric oxide synthase. The review next summarizes the renal antioxidant systems that protect against oxidative stress, including superoxide dismutase and catalase, the glutathione and thioredoxin systems, and others. Next, we describe how oxidative stress affects kidney function and promotes damage in every nephron segment, including the renal vessels, glomeruli, and tubules.

FUTURE DIRECTIONS

Despite the limited success associated with the application of antioxidants for treatment of kidney injury/disease thus far, preventing the generation and accumulation of ROS and RNS provides an ideal target for potential therapeutic treatments. The review discusses the shortcomings of antioxidant treatments previously used and the potential promise of new ones. Antioxid. Redox Signal. 25, 119-146.

High glucose induces autophagy of MC3T3-E1 cells via ROS-AKT-mTOR axis

In the present study, we investigate the function of ROS-AKT-mTOR axis on the apoptosis, proliferation and autophagy of MC3T3-E1 cells, and the proliferation of MC3T3-E1 cells after autophagy inhibition under high glucose conditions. MC3T3-E1 cells cultured in vitro were divided into the following groups: normal control group, N-acetylcysteine (NAC) group, 11.0 mM high glucose group, 11.0 mM high glucose + NAC group, 22.0 mM high glucose group, 22.0 mM high glucose + NAC group, CQ group, 22.0 mM high glucose + CQ group, 3-MA group and 3-MA + 22.0 mM high glucose group. ROS production was measured by DCFH-DA fluorescent probe. Cell proliferation was measured by MTT assay. Cells in different groups were stained with Annexin V-FITC/PI, and then apoptosis rate was detected by flow cytometry. Nucleus morphology was observed under fluorescence microscope after being incubated with Honchest33258. Protein expression was measured using Western blotting and immunofluorescence. Cell apoptosis and proliferation in high glucose group were increased and decreased, respectively, in a dose-dependent manner. Autophagy was significantly induced in high glucose group, even though different concentration of glucose induced autophagy in different stages of autophagy. ROS production in MC3T3-E1 cells was remarkably increased in high glucose group, but not in a dose-dependent manner. NAC, as an antioxidant, reduced ROS production and ameliorated cell apoptosis, proliferation abnormity and autophagy caused by high glucose. Expression of p-AKT and p-mTOR proteins were dramatically decreased in high glucose group, and NAC reversed their expression. In addition, 3-MA, an inhibitor of autophagy, significantly decreased the proliferation of MC3T3-E1 cells. When cocultured with 22.0 mM glucose that induced autophagy, proliferation of MC3T3-E1 cells was not affected compared to 22.0 mM high glucose group. Our present findings reveal that high glucose affects apoptosis, proliferation and autophagy of MC3T3-E1 cells through ROS-AKT-mTOR axis. In addition, autophagy inhibition does not affect the proliferation of MC3T3-E1 cells under high glucose conditions.

Oxidative Stress Related Diseases in Newborns

We review oxidative stress-related newborn disease and the mechanism of oxidative damage. In addition, we outline diagnostic and therapeutic strategies and future directions. Many reports have defined oxidative stress as an imbalance between an enhanced reactive oxygen/nitrogen species and the lack of protective ability of antioxidants. From that point of view, free radical-induced damage caused by oxidative stress seems to be a probable contributing factor to the pathogenesis of many newborn diseases, such as respiratory distress syndrome, bronchopulmonary dysplasia, periventricular leukomalacia, necrotizing enterocolitis, patent ductus arteriosus, and retinopathy of prematurity. We share the hope that the new understanding of the concept of oxidative stress and its relation to newborn diseases that has been made possible by new diagnostic techniques will throw light on the treatment of those diseases.

Role of Redox Status in Development of Glioblastoma

Glioblastoma multiforme (GBM) is a highly aggressive neoplasia, prognosis remains dismal, and current therapy is mostly palliative. There are no known risk factors associated with gliomagenesis; however, it is well established that chronic inflammation in brain tissue induces oxidative stress in astrocytes and microglia. High quantities of reactive species of oxygen into the cells can react with several macromolecules, including chromosomal and mitochondrial DNA, leading to damage and malfunction of DNA repair enzymes. These changes bring genetic instability and abnormal metabolic processes, favoring oxidative environment and increase rate of cell proliferation. In GBM, a high metabolic rate and increased basal levels of reactive oxygen species play an important role as chemical mediators in the regulation of signal transduction, protecting malignant cells from apoptosis, thus creating an immunosuppressive environment. New redox therapeutics could reduce oxidative stress preventing cellular damage and high mutation rate accompanied by chromosomal instability, reducing the immunosuppressive environment. In addition, therapies directed to modulate redox rate reduce resistance and moderate the high rate of cell proliferation, favoring apoptosis of tumoral cells. This review describes the redox status in GBM, and how this imbalance could promote gliomagenesis through genomic and mitochondrial DNA damage, inducing the pro-oxidant and proinflammatory environment involved in tumor cell proliferation, resistance, and immune escape. In addition, some therapeutic agents that modulate redox status and might be advantageous in therapy against GBM are described.

The effects of lutein on respiratory health across the life course: A systematic review

BACKGROUND

Lutein, a fat-soluble carotenoid present in green leafy vegetables and eggs, has strong antioxidant properties and could therefore be important for respiratory health.

DESIGN

We systematically reviewed the literature for articles that evaluated associations of lutein (intake, supplements or blood levels) with respiratory outcomes, published in Medline, Embase, Cochrane Central, PubMed, Web of Science and Google Scholar, up to August 2014.

RESULTS

We identified one Randomized Control Trial (RCT), two longitudinal, four prospective and six cross-sectional studies. The individual studies obtained a Quality Score ranging between 3 and 9. Six studies were performed in children, which examined bronchopulmonary dysplasia (BPD), asthma and wheezing. In adults, 7 studies investigated asthma, respiratory function and respiratory mortality. The RCT found a borderline significant effect of lutein/zeaxanthin supplementation in neonates on the risk of BPD (OR 0.43 (95% CI 0.15; 1.17). No association was found between lutein intake or levels and respiratory outcomes in children. A case-control study in adults showed lower lutein levels in asthma cases. Three studies, with a prospective or longitudinal study design, in adults found a small but a significant positive association between lutein intake or levels and respiratory function. No association was found in the other two studies. In relation to respiratory mortality, one longitudinal study showed that higher lutein blood levels were associated with a decreased mortality (HR 0.77 (95% CI 0.60; 0.99), per SD increase in lutein).

CONCLUSION

The published literature suggests a possible positive association between lutein and respiratory health. However, the literature is scarce and most studies are of observational nature.

Antioxidant potential of phenolic-rich two varieties of Nigerian local rice and their anti-cholinesterase activities after in vitro digestion

Purpose

– The purpose of this paper is to focus on the antioxidant properties of two phenolic-rich varieties of Nigerian local rice and their anti-cholinesterase potential after in vitro-simulated gastrointestinal digestion, with the aim of establishing their actual antioxidant and nutraceutical potential after their passage through the gastrointestinal tract upon consumption.

Design/methodology/approach

– Two local rice varieties, commonly referred to as “Gboko” and “Ofada” rice commonly grown in Benue State, a middle belt region of Nigeria and south western regions of Nigeria, respectively, were locally processed. Each of the processed grains were divided into two portions; one portion was left uncooked, while the second portion was boiled conventionally as eaten, dried and subsequently milled into powder. The milled samples of the raw and boiled rice were treated with acidified methanol to obtain the methanol extracts; another portion of each samples was subjected to in vitro enzyme digestion using standard methods to mimic human digestion; and the third portion was treated using the same scheme of in vitro digestion without the sets of enzyme which was used to serve as a control for enzyme treatment. The quali-quantitative phenolic profiles of the two local varieties were carried out with the aid of high-performance liquid chromatography with diode-array detection (HPLC-DAD) method. The antioxidant potential and anti-cholinesterase action of the methanolic extracts, the simulated in vitro digested model and the enzyme-treated controls of the rice samples were determined using standard methods and data obtained were subjected to ANOVA; the differences of means were separated using Duncan’s multiple range test (DMRT).

Findings

– The quali-quantitative assessment of phenolic compounds in the two studied local varieties revealed the presence of some phenolic acids and flavonoids, with a decreased level of most of the identified phenolic compounds after boiling. In vitro enzyme-digested rice for both raw and boiled rice samples showed significantly higher total phenolic content, total flavonoid content, ferric-reducing antioxidant power, 2, 2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS+) scavenging and NO− inhibitory activities than the aqueous-methanolic extracts and the enzyme-treated controls. The aqueous-methanolic extracts displayed a higher 1, 1 diphenyl-2-picrylhdrazyl radical scavenging activity and inhibited Fe2+-induced lipid oxidation in rat’s brain and liver homogenate than that displayed by the in vitro enzyme-digested samples. In vitro enzyme-digested and boiled “Gboko” and “Ofada” rice and raw “Ofada” rice have the potential of inhibiting acetylcholine esterase (AChE) activity. While methanolic extracts of raw and boiled “Ofada” and “Gboko” rice exhibited the potential to inhibit butrylcholinesterase activity. The result of this paper indicates that the selected rice varieties possess antioxidant capacities which are better released after the simulated in vitro enzyme digestion; the result also showed the anti-cholinesterase potential of the studied rice grains and, therefore, they can be considered as nutraceutical health supplements.

Originality/value

– The paper has demonstrated the antioxidant potentials of the phenolic-containing two Nigerian local rice varieties and established their anti-cholinesterase potential after simulated in vitro enzyme digestion.

Peroxidase Enzymes Regulate Collagen Biosynthesis and Matrix Mineralization by Cultured Human Osteoblasts

The early recruitment of inflammatory cells to sites of bone fracture and trauma is a critical determinant in successful fracture healing. Released by infiltrating inflammatory cells, myeloperoxidase (MPO) and eosinophil peroxidase (EPO) are heme-containing enzymes, whose functional involvement in bone repair has mainly been studied in the context of providing a mechanism for oxidative defense against invading microorganisms. We report here novel findings that show peroxidase enzymes have the capacity to stimulate osteoblastic cells to secrete collagen I protein and generate a mineralized extracellular matrix in vitro. Mechanistic studies conducted using cultured osteoblasts show that peroxidase enzymes stimulate collagen biosynthesis at a post-translational level in a prolyl hydroxylase-dependent manner, which does not require ascorbic acid. Our studies demonstrate that osteoblasts rapidly bind and internalize both MPO and EPO, and the catalytic activity of these peroxidase enzymes is essential to support collagen I biosynthesis and subsequent release of collagen by osteoblasts. We show that EPO is capable of regulating osteogenic gene expression and matrix mineralization in culture, suggesting that peroxidase enzymes may play an important role not only in normal bone repair, but also in the progression of pathological states where infiltrating inflammatory cells are known to deposit peroxidases.

Dichlorodiphenyldichloroethylene exposure reduces r-GCS via suppressed Nrf2 in HepG2 cells

p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), the major isomer of persistent 1,1-Bis(4-chlorophenyl)-2,2,2-trichloroethane metabolite, is highly associated with the risk of liver cancer. γ-glutamyl-cysteine synthetase (γ-GCS), which is the rate-limiting enzyme of glutathione (GSH) biosynthesis and an important scavenger of reactive oxygen species (ROS), is considered as a potential therapeutic target for many cancers. However, the association between the body burden of p,p'-DDE and γ-GCS has not been fully established. Here, we indicated that low doses of p,p'-DDE exposure promoted the proliferation and decreased γ-GCS activity of HepG2 cells in a dose- and time-dependent manner. In addition, p,p'-DDE elevated ROS content and attenuated glutathione peroxidase activity. This was accompanied with inhibitions of NF-E2-related factor 2 (Nrf2) at the mRNA and protein levels. ROS inhibitor supplement could significantly reverse these effects. Moreover, the addition of the proteasome inhibitor, MG132, strongly reversed the p,p'-DDE-reduced Nrf2 expression and γ-GCS activity. Consistently, GSH content was in line with the alteration of γ-GCS. Collectively, the results indicate that p,p'-DDE treatment downregulates γ-GCS activity in HepG2 cells by inducing ROS-mediated Nrf2 loss.

Nicotine Enhances High-Fat Diet-Induced Oxidative Stress in the Kidney

INTRODUCTION

Life expectancy of an obese smoker is 13 years less than a normal weight smoker, which could be linked to the increased renal risk imposed by smoking. Both smoking-through nicotine (NIC)-and obesity-by free fatty acid overload-provoke oxidative stress in the kidney, which ultimately results in development of chronic kidney injury. Their combined renal risk, however, is virtually unknown. We tested the hypothesis that chronic NIC exposure worsens renal oxidative stress in mice on high-fat diet (HFD) by altering the balance between expression of pro-oxidant and antioxidant genes.

METHODS

Nine-week-old male C57Bl/6J mice consumed normal diet (ND) or HFD and received either NIC (200 μg/ml) or vehicle (2% saccharine) in their drinking water. Body weight, plasma clinical parameters, renal lipid deposition, markers of renal oxidative stress and injury, as well as renal expression of the pro-oxidant p66shc and the antioxidant MnSOD were determined after 12 weeks.

RESULTS

NIC significantly augmented levels of circulating free fatty acid, as well as lipid deposition, oxidative stress and sublethal injury in the kidneys of mice on HFD. In addition, NIC exposure suppressed HFD-mediated induction of MnSOD while increased expression of p66shc in the kidney.

CONCLUSIONS

Tobacco smoking or the increasingly popular E-cigarettes-via NIC exposure-could worsen obesity-associated lipotoxicity in the kidney. Hence, our findings could help to develop strategies that mitigate adverse effects of NIC on the obese kidney.

IMPLICATIONS

Life expectancy of an obese smoker is 13 years less than a normal weight smoker, which could be linked to the increased renal risk imposed by smoking. NIC-the main component of tobacco smoke, E-cigarettes and replacement therapies-links smoking to renal injury via oxidative stress, which could superimpose renal oxidative stress caused by obesity. Our results substantiate this scenario using a mouse model of diet induced obesity and NIC exposure and imply the augmented long-term renal risk in obese smokers. Also, our study may help to develop strategies that mitigate adverse effects of NIC on the obese kidney.

The Outflow Pathway: A Tissue With Morphological and Functional Unity

The trabecular meshwork (TM) plays an important role in high-tension glaucomas. Indeed, the TM is a true organ, through which the aqueous humor flows from the anterior chamber to Schlemm's canal (SC). Until recently, the TM, which is constituted by endothelial-like cells, was described as a kind of passive filter. In reality, it is much more. The cells delineating the structures of the collagen framework of the TM are endowed with a cytoskeleton, and are thus able to change their shape. These cells also have the ability to secrete the extracellular matrix, which expresses proteins and cytokines, and are capable of phagocytosis and autophagy. The cytoskeleton is attached to the nuclear membrane and can, in millionths of a second, send signals to the nucleus in order to alter the expression of genes in an attempt to adapt to biomechanical insult. Oxidative stress, as happens in aging, has a deleterious effect on the TM, leading eventually to cell decay, tissue malfunction, subclinical inflammation, changes in the extracellular matrix and cytoskeleton, altered motility, reduced outflow facility, and (ultimately) increased IOP. TM failure is the most relevant factor in the cascade of events triggering apoptosis in the inner retinal layers, including ganglion cells. J. Cell. Physiol. 231: 1876-1893, 2016. © 2016 Wiley Periodicals, Inc.

Inhibition of Prostaglandin Reductase 2, a Putative Oncogene Overexpressed in Human Pancreatic Adenocarcinoma, Induces Oxidative Stress-Mediated Cell Death Involving xCT and CTH Gene Expressions through 15-Keto-PGE2

Prostaglandin reductase 2 (PTGR2) is the enzyme that catalyzes 15-keto-PGE₂, an endogenous PPARγ ligand, into 13,14-dihydro-15-keto-PGE₂. Previously, we have reported a novel oncogenic role of PTGR2 in gastric cancer, where PTGR2 was discovered to modulate ROS-mediated cell death and tumor transformation. In the present study, we demonstrated the oncogenic potency of PTGR2 in pancreatic cancer. First, we observed that the majority of the human pancreatic ductal adenocarcinoma tissues was stained positive for PTGR2 expression but not in the adjacent normal parts. In vitro analyses showed that silencing of PTGR2 expression enhanced ROS production, suppressed pancreatic cell proliferation, and promoted cell death through increasing 15-keto-PGE₂. Mechanistically, silencing of PTGR2 or addition of 15-keto-PGE₂ suppressed the expressions of solute carrier family 7 member 11 (xCT) and cystathionine gamma-lyase (CTH), two important providers of intracellular cysteine for the generation of glutathione (GSH), which is widely accepted as the first-line antioxidative defense. The oxidative stress-mediated cell death after silencing of PTGR2 or addition of 15-keto-PGE₂ was further abolished after restoring intracellular GSH concentrations and cysteine supply by N-acetyl-_L-cysteine and 2-Mercaptomethanol. Our data highlight the therapeutic potential of targeting PTGR2/15-keto-PGE₂ for pancreatic cancer.

Reactivation of p53 by a Cytoskeletal Sensor to Control the Balance Between DNA Damage and Tumor Dissemination

BACKGROUND

Abnormal cell migration and invasion underlie metastasis, and actomyosin contractility is a key regulator of tumor invasion. The links between cancer migratory behavior and DNA damage are poorly understood.

METHODS

Using 3D collagen systems to recapitulate melanoma extracellular matrix, we analyzed the relationship between the actomyosin cytoskeleton of migrating cells and DNA damage. We used multiple melanoma cell lines and microarray analysis to study changes in gene expression and in vivo intravital imaging (n = 7 mice per condition) to understand how DNA damage impacts invasive behavior. We used Protein Tissue Microarrays (n = 164 melanomas) and patient databases (n = 354 melanoma samples) to investigate the associations between markers of DNA damage and actomyosin cytoskeletal features. Data were analyzed with Student's and multiple t tests, Mann-Whitney's test, one-way analysis of variance, and Pearson correlation. All statistical tests were two-sided.

RESULTS

Melanoma cells with low levels of Rho-ROCK-driven actomyosin are subjected to oxidative stress-dependent DNA damage and ATM-mediated p53 protein stabilization. This results in a specific transcriptional signature enriched in DNA damage/oxidative stress responsive genes, including Tumor Protein p53 Inducible Protein 3 (TP53I3 or PIG3). PIG3, which functions in DNA damage repair, uses an unexpected catalytic mechanism to suppress Rho-ROCK activity and impair tumor invasion in vivo. This regulation was suppressed by antioxidants. Furthermore, PIG3 levels decreased while ROCK1/2 levels increased in human metastatic melanomas (ROCK1 vs PIG3; r = -0.2261, P < .0001; ROCK2 vs PIG3: r = -0.1381, P = .0093).

CONCLUSIONS

The results suggest using Rho-kinase inhibitors to reactivate the p53-PIG3 axis as a novel therapeutic strategy; we suggest that the use of antioxidants in melanoma should be very carefully evaluated.

Protocatechuic aldehyde inhibits TNF-α-induced fibronectin expression in human umbilical vein endothelial cells via a c-Jun N-terminal kinase dependent pathway

Fibronectin (FN) is one of the most important extracellular matrix proteins and plays an important role in the pathogenesis of atherosclerosis (AS). The aim of the present study was to evaluate the effect of a potent, water-soluble antioxidant, protocatechuic aldehyde (PA), which is derived from the Chinese herb Salvia miltiorrhiza, on the expression of FN in human umbilical vein endothelial cells (HUVECs) stimulated with tumor necrosis factor-α (TNF-α). The pharmacological effects of PA on the production of FN were investigated using ELISA and western blot analysis. In addition, ELISA and western blot analysis were used to examine the activation and suppression of the mitogen-activated protein kinase (MAPK) pathways and nuclear factor (NF)-κB in TNF-α-stimulated HUVECs, in order to explore the underlying pharmacological mechanism of PA. The inhibitory effect of PA on the total generation of reactive oxygen species (ROS) in TNF-α-stimulated HUVECs was assessed using 2',7'-dichlorofluorescein diacetate. Pretreatment of HUVECs with PA (0.15, 0.45 and 1.35 mM) for 18 h markedly attenuated the TNF-α-stimulated FN surface expression and secretion in a dose-dependent manner. Intracellular ROS generation and the expression of extracellular signal-regulated kinase 1 and 2 (ERK1/2), c-Jun N-terminal kinase (JNK) and p38 MAPK (p38) were significantly induced by TNF-α (2 ng/ml) in HUVECs. TNF-α-induced ROS generation and JNK activation were inhibited by PA in a concentration-dependent manner. By contrast, ERK1/2 and p38 activation was not significantly affected by PA. Pretreatment of HUVECs with PA for 18 h markedly attenuated TNF-α-stimulated NF-κB activation. In conclusion, the present findings suggest that PA inhibits TNF-α-induced FN expression in HUVECs through a mechanism that involves ROS/JNK and NF-κB.