Reactive Oxygen Species Mediators Research Articles

Diabetes and Heart Failure: Multi-Omics Approaches.

Diabetes and heart failure, as important global issues, cause substantial expenses to countries and medical systems because of the morbidity and mortality rates. Most people with diabetes suffer from type 2 diabetes, which has an amplifying effect on the prevalence and severity of many health problems such as stroke, neuropathy, retinopathy, kidney injuries, and cardiovascular disease. Type 2 diabetes is one of the cornerstones of heart failure, another health epidemic, with 44% prevalence. Therefore, finding and targeting specific molecular and cellular pathways involved in the pathophysiology of each disease, either in diagnosis or treatment, will be beneficial. For diabetic cardiomyopathy, there are several mechanisms through which clinical heart failure is developed; oxidative stress with mediation of reactive oxygen species (ROS), reduced myocardial perfusion due to endothelial dysfunction, autonomic dysfunction, and metabolic changes, such as impaired glucose levels caused by insulin resistance, are the four main mechanisms. In the field of oxidative stress, advanced glycation end products (AGEs), protein kinase C (PKC), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) are the key mediators that new omics-driven methods can target. Besides, diabetes can affect myocardial function by impairing calcium (Ca) homeostasis, the mechanism in which reduced protein phosphatase 1 (PP1), sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2a (SERCA2a), and phosphorylated SERCA2a expressions are the main effectors. This article reviewed the recent omics-driven discoveries in the diagnosis and treatment of type 2 diabetes and heart failure with focus on the common molecular mechanisms.

Evaluation of Antioxidant, Antityrosinase Activities and Cytotoxic Effects of Phyllanthus amarus Extracts

Background: Antioxidant and antityrosinase activities of medicinal plants, together with their various health benefits have received attention in recent times. However, with wide ethnobotanical uses of Phyllanthus amarus, data on in-vitro skin depigmentation activity and cytotoxicity, as well as its impact on mediators of Reactive Oxygen Species (ROS) are still lacking. This present study is, therefore, designed to evaluate its tyrosinase inhibitory action, antioxidant potentials and cytotoxic activities. Methods: In this study, quantitative determination of polyphenols, flavanol, flavonol, flavonoids, Oxygen Reducing Antioxidant Capacity (ORAC), Trolox Equivalent Antioxidant Capacity (TEAC) were performed on the extracts of P amarus. Also, tyrosinase inhibitory efficacy of the hexane, methanol and aqueous extracts of Phyllanthus amarus were evaluated using ELISA-based methods. Cytotoxicity studies were done with mouse Sertoli (TM4) cells, using MTT assay and cell counts. Results: The hexane and aqueous extracts exhibited significant antityrosinase activity (p<0.05) (IC50= 116.08 and 129.25 µg/mL respectively) while its methanolic extract produces no statistically significant finding. Higher total polyphenol, flavonoids and flavonol were seen in the methanol fraction of the extract. Besides, higher radical cation scavenging (TEAC) activity was observed in the aqueous extract. These values were significant (p<0.0001), whereas ORAC results of the methanol extract show significantly (p<0.0001) higher oxygen reducing antioxidant potential than the aqueous extract. The aqueous extract showed the highest mitochondrial dehydrogenase activity at lower concentrations (0.01 to 10 μg/ml). Here, TM4 cell numbers were also significantly higher as compared to the untreated control. Sertoli cell viability was compromised after exposure to higher extract concentrations (100 to 1000 µg/ml). Conclusion: The hexane and aqueous extracts of Phyllanthus amarus possess good tyrosinase inhibitory action when compared to the reference kojic acid. Also, it demonstrated high antioxidant potentials by its ability to scavenge oxygen radicals, reduce ferric ion and inhibit ABTS radical. Lower extract concentrations stimulated Sertoli cell proliferation, which might be due to phytoestrogenic activities of Phyllanthus amarus conferred by its active, components, such as phyllanthin and hypophyllanthin.

Blockade of JAK2/STAT3 intensifies the anti-tumor activity of arsenic trioxide in acute myeloid leukemia cells: Novel synergistic mechanism via the mediation of reactive oxygen species

Reactive oxygen species (ROS) are essential mediators of crucial cellular processes including apoptosis, proliferation, survival and cell cycle. Their regulatory role in cancer progression has seen in different human malignancies such as acute myeloid leukemia (AML). AML patients suffer from high resistance of the tumors against routine therapeutics including ATO. ATO enhance reactive oxygen species levels and induce apoptosis and suppresses proliferation in AML cells. However, some pathways such as JAK2/STAT3 ease anti-tumor activity of ATO by reducing reactive oxygen species amount and protecting the cell from apoptosis. In the present study, we use ruxolitinib (potent JAK2 inhibitor) to increase the sensitivity of AML cells to ATO treatment. We test, the effect of this combination on metabolic activity, proliferation, colony formation, cell cycle distribution, apoptosis, oxidative stress and DNA damage. Our results showed that combination of ATO with ruxolitinib synergistically reduced metabolic activity, proliferation and survival of AML cell lines. This combination induced G1/S cell cycle arrest because of reactive oxygen species elevation and GSH reduction. Besides, enhancement of reactive oxygen species increased apoptosis rate in combination samples. We uncovered that the synergistic anti-tumor effect of ATO and ruxolitinib in AML cells mediates via reactive oxygen species elevation and DNA damage. Overall, our results show that the combinatorial therapy of AML cells is more effective than solo-targeted therapy.

Coptisine-induced cell cycle arrest at G2/M phase and reactive oxygen species-dependent mitochondria-mediated apoptosis in non-small-cell lung cancer A549 cells.

This study aimed to explore the effect of coptisine on non-small-cell lung cancer and its mechanism through various in vitro cellular models (A549). Results claimed significant inhibition of proliferation by coptisine against A549, H460, and H2170 cells with IC50 values of 18.09, 29.50, and 21.60 µM, respectively. Also, coptisine exhibited upregulation of pH2AX, cell cycle arrest at G2/M phase, and downregulation of the expression of cyclin B1, cdc2, and cdc25C and upregulation of p21 dose dependently. Furthermore, induction of apoptosis in A549 cells by coptisine was characterized by the activation of caspase 9, caspase 8, and caspase 3, and cleavage of poly adenosine diphosphate ribose polymerase. In addition, coptisine was found to increase reactive oxygen species generation, upregulate Bax/Bcl-2 ratio, disrupt mitochondrial membrane potential, and cause cytochrome c release into the cytosol. Besides, treatment with a reactive oxygen species inhibitor (N-acetyl cysteine) abrogated coptisine-induced growth inhibition, apoptosis, reactive oxygen species generation, and mitochondrial dysfunction. Thus, the mediation of reactive oxygen species in the apoptosis-induced effect of coptisine in A549 cells was corroborated. These findings have offered new insights into the effect and mechanisms of action of coptisine against non-small-cell lung cancer.

Abstract 1240: Bioactive proanthocyanidins from grape seeds inhibit cigarette smoke condensate-enhanced invasion of human non-small cell lung cancer cells by targeting NADPH oxidase and epithelial-mesenchymal transition

Abstract Lung cancer is the leading cause of cancer-related deaths in the United States, and the dismal 5-year survival rate of approximately 14% has shown no improvement over the past three decades. Cigarette smoke (CS) is the cause of ∼90% of lung cancer cases, and promotes drug resistance in lung cancer patients and is even known to limit effectiveness of treatment of cancers of other organs. It is therefore important to develop more effective strategies targeting CS-induced molecular abnormalities. Cigarette smoking increases oxidative stress particularly via activation of NADPH oxidase (NOX), a key source of superoxide anion production. Here we report the inhibitory effects of bioactive phytochemicals, grape seed proanthocyanidins (GSPs), on the migration potential of human non-small cell lung cancer (NSCLC) cells (A549, H460 and H1299) and assessed whether CS-induced NOX activation is their target. Using an in vitro invasion assay, we found that treatment of NSCLC cells with CS condensate (CSC) increased the migration of NSCLC cells in a dose-dependent manner, via enhancing NOX mediated-reactive oxygen species (ROS) accumulation. Treatment of NSCLC cells with GSPs inhibited the cell migration via reduction in ROS accumulation or oxidative stress and subsequent reduction of epithelial-to-mesenchymal transition. To examine the molecular targets of GSPs, we studied the effect of GSPs on CSC-induced alterations in the levels of key NOX components, namely, p22phox and p47phox, using A549 cells. We also determined the effect of GSPs on CSC-induced interaction between p22phox and p47phox proteins, a key event in NOX activation. Our results indicate that treatment of A549 cells with GSPs not only reverse CSC-induced expression levels of p22phox and p47phox, but also inhibit CSC-induced NOX activation by decreasing the binding of p22phox and p47phox proteins. This new insight into the anti-lung cancer cell migration activity of GSPs could serve as a basis for chemoprevention or therapy of advanced stage of lung cancer in human patients. Citation Format: Mudit Vaid, Santosh K. Katiyar. Bioactive proanthocyanidins from grape seeds inhibit cigarette smoke condensate-enhanced invasion of human non-small cell lung cancer cells by targeting NADPH oxidase and epithelial-mesenchymal transition. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1240. doi:10.1158/1538-7445.AM2014-1240

Sub-inhibitory fosmidomycin exposures elicits oxidative stress in Salmonella enterica serovar Typhimurium LT2.

Fosmidomycin is a time-dependent nanomolar inhibitor of methylerythritol phosphate (MEP) synthase, which is the enzyme that catalyzes the first committed step in the MEP pathway to isoprenoids. Importantly, fosmidomycin is one of only a few MEP pathway-specific inhibitors that exhibits antimicrobial activity. Most inhibitors identified to date only exhibit activity against isolated pathway enzymes. The MEP pathway is the sole route to isoprenoids in many bacteria, yet has no human homologs. The development of inhibitors of this pathway holds promise as novel antimicrobial agents. Similarly, analyses of the bacterial response toward MEP pathway inhibitors provides valuable information toward the understanding of how emergent resistance may ultimately develop to this class of antibiotics. We have examined the transcriptional response of Salmonella enterica serovar typhimurium LT2 to sub-inhibitory concentrations of fosmidomycin via cDNA microarray and RT-PCR. Within the regulated genes identified by microarray were a number of genes encoding enzymes associated with the mediation of reactive oxygen species (ROS). Regulation of a panel of genes implicated in the response of cells to oxidative stress (including genes for catalases, superoxide dismutases, and alkylhydrogen peroxide reductases) was investigated and mild upregulation in some members was observed as a function of fosmidomycin exposure over time. The extent of regulation of these genes was similar to that observed for comparable exposures to kanamycin, but differed significantly from tetracycline. Furthermore, S. typhimurium exposed to sub-inhibitory concentrations of fosmidomycin displayed an increased sensitivity to exogenous H2O2 relative to either untreated controls or kanamycin-treated cells. Our results suggest that endogenous oxidative stress is one consequence of exposures to fosmidomycin, likely through the temporal depletion of intracellular isoprenoids themselves, rather than other mechanisms that have been proposed to facilitate ROS accumulation in bacteria (e.g. cell death processes or the ability of the antibiotic to redox cycle).

EVALUATION OF RENAL PROTECTIVE ACTIVITY OF ADHATODA ZEYLANICA (MEDIC) LEAVES EXTRACT IN WISTAR RATS

AbstractThe kidney is especially a susceptible organ to toxic injuries by drugs and toxin, because of a high blood supply and the presence of cellular transport systems that cause accumulation of these compounds within the nephron epithelial cells. Glomerular, tubular and interstitial cells frequently encounter significant concentrations of medications and their metabolites, which can induce changes in kidney function and structure. Renal toxicity can be a result of hemodynamic changes, direct injury to cells and tissue, inflammatory tissue injury and/or obstruction of renal excretion.Gentamicin is potent broad spectrum antibiotic therapeutic agent used in a number of infective conditions. Because of the obvious mediation of Reactive Oxygen Species in Gentamicin induced renal damage. Several antioxidant agents have been used to block Gentamicin nephrotoxicity.There is a proven converse relationship between the consumption of antioxidant rich plants incidence of human diseases. A primary goal of this study is to present the scientific evidence for the use of common herb Adhatoda zeylanica as supplementary in the gentamicin treated acute renal failure (ARF) subjects. The beneficial effect of A. Zeylanica against gentamicin nephrotoxicity, possibly depends on its ability to scavenge the gentamicin induced free radicals.This study demonstrates the effectiveness of the extract improved with the polarity of the solvents over a period of 10 days and the plant has the potential to ameliorate Gentamicin nephrotoxicity.

Endophytic mediation of reactive oxygen species and antioxidant activity in plants: a review

Reactive oxygen species are in all types of organisms from microbes to higher plants and animals. They are by-products of normal metabolism, such as photosynthesis and respiration, and are responsive to abiotic and biotic stress. Accumulating evidence suggests reactive oxygen species play a vital role in programmed cell death, stress responses, plant defense against pathogens and systemic stress signaling in conjunction with antioxidant production. Here, we propose that reactive oxygen species and antioxidants, as both universal and evolutionarily conserved, are likely to play important role(s) in symbiotic interactions. To support this hypothesis we review the root and foliar fungal endophyte literature specific to fungal-plant symbiotum production of reactive oxygen species and antioxidants in response to stress. These asymptomatic fungi can produce antioxidants in response to both biotic and abiotic stress when grown in culture as well as in planta. In addition, there is a growing but nascent literature reporting a significant impact of endophyte colonization on the antioxidant activity of colonized (E+) hosts when compared to uncolonized (E-) hosts, especially when exposed to stress. Here we summarize general patterns emerging from the growing literature specific to antioxidant activity of endophytes in colonized hosts and bring up possible future research questions and approaches. The consequences of changes in reactive oxygen species production and increased antioxidant activity in the symbiotum appear to be beneficial in many instances; but costs are also indicated. Unexplored questions are: 1) to what extent do antioxidants originating from the fungal endophyte mediate host metabolism, and thereby control host responses to endophyte colonization; (2) what role do fungal, plant, or symbiotum produced reactive oxygen species and antioxidants have in determining symbiotic outcome between extremes of pathogenicity and mutualism; and (3) what role if any, do the production of reactive oxygen species and their antioxidant counterparts play in the symbiotum’s ability to respond to changing selection pressures? If as the literature suggests, such endophyte imposed mediation can be utilized to foster increases in plant production in resource limited habitats then the utilization of fungal endophytes may prove useful in agronomic and conservation settings.

DDB2, a critical mediator of reactive oxygen species

Oxidative stress is an imbalance between free radical formation and anti‐oxidant defense. Reactive Oxygen Species (ROS) have been implicated in several pathological disorders. Here, we reveal a novel function of the nucleotide excision repair protein DDB2 in ROS accumulation. DDB2 deficient cells fail to accumulate ROS following DNA damage. The lack of ROS accumulation in DDB2 deficiency results from high‐level expression of the anti‐oxidant genes, in vitro and in vivo. In the absence of DDB2, the antioxidant genes MnSOD and Catalase are expressed at high levels leading to an inhibition of ROS accumulation. DDB2 represses the expression of these anti‐oxidant genes by recruiting Cul4a and Suv39h and by increasing Histone‐H3K9 tri‐methylation. Moreover, expression of DDB2 also is induced by ROS. Together, our results show that upon oxidative stress, DDB2 functions in a positive feedback loop by repressing the ROS scavenger genes, such as MnSOD and Catalase, to cause a persistent accumulation of ROS in the cell.

SOD/catalase mimetic platinum nanoparticles inhibit heat-induced apoptosis in human lymphoma U937 and HH cells

Platinum nanoparticles (Pt-NPs) are known to possess anti-tumouric activity and the ability to scavenge superoxides and peroxides indicating that they can act as superoxide dismutase (SOD)/catalase mimetics. These potentials seem useful in the protection and/or amelioration of oxidative stress-associated pathologies, but, when they are combined with a therapeutic modality that depends upon the mediation of reactive oxygen species in cell killing induction, the effect of Pt-NPs might be questionable. Here, the effects of polyacrylic acid-capped Pt-NPs (nano-Pts) on hyperthermia (HT)-induced apoptosis and the underlying molecular mechanisms were investigated in human myelomonocytic lymphoma U937 and human cutaneous T-cell lymphoma HH cells. The results showed that the pre-treatment with nano-Pts significantly inhibited HT-induced apoptosis in a dose-dependent manner. Superoxide, but not peroxides, was suppressed to varying extents. All pathways involved in apoptosis execution were also negatively affected. The results reveal that the combination of nano-Pts and HT could result in HT-desensitization.

THE EFFECT OF ENVIRONMENTAL FACTORS ON BIOSYNTHESIS OF CAROTENOIDS AND POLYPHENOLICS IN FRUITS AND VEGETABLES: A REVIEW AND PROSPECTS

There is a lack of basic knowledge about the effects of environmental factors on the concentration of secondary metabolites in fruits and vegetables. While metabolic pathways are increasingly better described, the effects of environmental factors remain insufficiently understood and quantified. The objective of this presentation is to review the major hypotheses about the effect of environmental factors on biosynthesis and accumulation of carotenoids and polyphenolic compounds in fruits and vegetables, with the exception of quality of light. Firstly, the primary and the secondary metabolisms are interlinked. Biosynthesis of carotenoids and polyphenolic compounds depends on the carbon status. Secondly, it is now well-established that secondary metabolites play a key-role in adaptation of plants to environmental constraints. More specifically, observations strongly suggest that biotic and abiotic constraints may influence the synthesis of carotenoids through the mediation of Reactive Oxygen Species (ROS). All these hypotheses and the prospects of modelling are presented and discussed from a controlling point of view with our objective being to design innovative cropping techniques for farmers in developed and developing countries which will help them to produce fruits and vegetables with enhanced concentrations in phytochemicals without resorting to GMO. The idea is discussed that organic farming results in fruits and vegetables with increased concentrations in polyphenolics, and possibly carotenoids, contributing to health benefits, because they are more stressed. (Resume d'auteur)

SOCS1 protects protein tyrosine phosphatases by thioredoxin upregulation and attenuates Jaks to suppress ROS-mediated apoptosis

Suppressors of cytokine signaling (SOCS) are negative regulators of cytokine-induced signal transduction, which play multiple roles in cell growth, differentiation and apoptosis. In this study, the regulatory role of SOCS in oxidative stress-induced apoptosis was investigated. In Jurkat T cells and mouse splenocytes, we have found that SOCS1 is induced in response to tumor necrosis factor-alpha or H(2)O(2), concomitant with the activation of Jaks which act as important mediators of reactive oxygen species (ROS)-induced apoptosis upstream of p38 mitogen-activated protein kinase. Using SOCS1 overexpressing or knockdown Jurkat T-cell systems we clearly demonstrate that, SOCS1 inhibits the ROS-mediated apoptosis. The antiapoptotic action of SOCS1 was exerted not only by suppressing Jaks, but also by sustaining protein tyrosine phosphatase (PTP) activities. Notably, SOCS1-transduced cells displayed increase in thioredoxin levels and decrease in ROS generation induced by oxidative stress. In addition, the Jak-inhibiting and PTP-sustaining effect of SOCS1 was significantly reduced on thioredoxin ablation. Moreover, coimmunoprecipitation data revealed molecular interaction of SHP1 or CD45 with thioredoxin, which was promoted in SOCS1-transfected cells. Together, our data strongly suggest that both the protection of PTPs by thioredoxin from ROS attack and the attenuation of Jaks account for the antiapoptotic function of SOCS1 in immune cells under oxidative stress.

Role of NADPH oxidase in angiotensin II induced endothelin‐1 expression within vascular adventitial fibroblasts

Recent studies have demonstrated that under Angiotensin II (Ang II) treatment, adventitial fibroblasts are able to express Endothelin-1 (ET-1), a result which led to increased collagen I expression. However, mediation of the Ang II induced ET-1 expression through NADPH oxidase in adventitial fibroblasts remains uncertain. The purpose of the present study was to determine if NADPH oxidase in adventitial fibroblasts mediates Ang II induced ET-1 expression. Vascular adventitial fibroblasts were isolated mouse aorta and treated with Ang II (10-7 M) in the presence or absence of apocynin (10-5M), a specific NADPH oxidase inhibitor. PreporET-1 mRNA was determined by relative RT-PCR. ET-1 peptide levels in medium were determined via ELISA. Ang II (10-7 M) treatment significantly increased both preproET-1 mRNA and ET-1 peptide levels (p<0.05), which were significantly decreased by DPI (10-5M). In addition, the Ang II induced ET-1 expressions were decreased in cells isolated from the gp91 knock out mice, which lacked a key subunit of NADPH oxidase, therefore decreasing functionality. In conclusion, ET-1 mRNA and peptide levels are increased after Ang II treatment. Moreover, NADPH oxidase, an important mediator of reactive oxygen species does seem to play an important role in the Ang II induced ET-1 expression in adventitial fibroblasts.

Normal status of hepatic 7-ethoxyresorufin O-deethylase (EROD) activity, antioxidant enzymes and DNA oxidation in turbot ( Scophthalmus maximus) and other flatfish species following exposure to nitroaromatic compounds

Nitroaromatics may be metabolized both to reactive electrophiles and to mediators of reactive oxygen species (ROS) formation. Hepatic effects of nitroaromatic compounds were investigated in three species of flatfish. No changes were seen in 7-ethoxyresorufin O-deethylase (EROD) activity in turbot ( Scophthalmus maximus) exposed (i.p. 48 h) to either 1-nitropyrene or nitrofurantoin, indicating non-induction of cytochrome P4501A. Similarly, no changes were seen in any antioxidant enzyme activities (superoxide dismutase, catalase, glutathione peroxidase, DT-diaphorase, aldehyde dehydrogenase). DNA oxidative damage was indicated to be a widespread endogenous phenomenon by the presence of 8-hydroxydeoxyguanosine (8OHdG) in liver of S. maximus, dab ( Limanda limanda) and sole ( Solea solea). No increase in 8OHdG levels were seen in S. maximus, L. limanda or S. solea exposed to nitrofurantoin. The results for 8OHdG were in contrast to those reported for English sole ( Parophrys vetulus) which showed an increase in hepatic levels following similar nitrofurantoin treatment (Nishimoto et al., 1991). 32P-post-labelling analysis of liver from exposed S. maximus showed no evidence of DNA adducts with chomatographic conditions able to detect 1-nitro-pyrene-derived DNA adducts in rat. None of the various parameters studied appear to be suitable as biomarkers for the detection of exposure to nitroaromatics in the aquatic environment.