SEARCH · PubMed Health

Results for “ROS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,045 records · Page 58Linked to original sources

PubMed2006

CTLA-4IG suppresses reactive oxygen species by preventing synovial adherent cell-induced inactivation of Rap1, a Ras family GTPASE mediator of oxidative stress in rheumatoid arthritis T cells.

OBJECTIVE: Oxidative stress contributes to the inflammatory properties of rheumatoid arthritis (RA) synovial T lymphocytes. This study was undertaken to investigate the mechanisms leading to production of reactive oxygen species (ROS) and oxidative stress in RA synovial T lymphocytes. METHODS: ROS production in T lymphocytes from the peripheral blood (PB) of healthy donors and from the PB and synovial fluid (SF) of RA patients was measured by ROS-dependent fluorescence of 6-carboxy-2',7'-dichlorofluorescein. Rap1 GTPase activation was assessed by activation-specific probe precipitation. Proliferation of RA PB and SF T lymphocytes was assayed by 3H-thymidine incorporation. In some experiments, RA PB T cells were preincubated with autologous SF or with PB or SF adherent cells. Experiments were performed in the absence or presence of transwell membranes or CTLA-4Ig fusion proteins. Short- and long-term stimulations of healthy donor PB T lymphocytes were performed with inflammatory cytokines, in the absence or presence of activating anti-CD28 antibodies. RESULTS: T lymphocyte ROS production and Rap1 inactivation were mediated by cell-cell contact with RA synovial adherent cells, and this correlated with T cell mitogenic hyporesponsiveness. CTLA4-Ig blockade of synovial adherent cell signaling to CD28 T cells reversed the inhibition of Rap1 activity and prevented induction of ROS. Introduction of active RapV12 into T cells also prevented induction of ROS production. Coincubation of T cells with stimulating anti-CD28 antibodies and inflammatory cytokines synergistically increased T cell ROS production. CONCLUSION: Cell-cell contact between T cells and RA synovial adherent cells mediates Rap1 inactivation and subsequent ROS production in T lymphocytes following exposure to inflammatory cytokines. This process can be blocked by CTLA4-Ig fusion protein.

Abatacept↗

PubMed2005

NAD(P)H oxidase plays a crucial role in PDGF-induced proliferation of hepatic stellate cells.

The proliferation of hepatic stellate cells (HSCs) is a critical step in hepatic fibrogenesis. Platelet-derived growth factor (PDGF) is the most potent mitogen for HSCs. We investigated the role of nonphagocytic NAD(P)H oxidase-derived reactive oxygen species (ROS) in PDGF-induced HSC proliferation. The human HSC line, LI-90 cells, murine primary-cultured HSCs, and PDGF-BB were used in this study. We examined the mechanism of PDGF-BB-induced HSC proliferation in relation to the role of a ROS scavenger and diphenylene iodonium, an inhibitor of NAD(P)H oxidase. We also measured ROS production with the aid of chemiluminescence. We showed that PDGF-BB induced proliferation of HSCs through the intracellular production of ROS. We also demonstrated that HSCs expressed key components of nonphagocytic NAD(P)H oxidase (p22phox, gp91phox, p47phox, and p67phox) at both the messenger RNA and protein levels. Diphenylene iodonium suppressed PDGF-BB-induced ROS production and HSC proliferation. Coincubation of H2O2 and PDGF-BB restored the proliferation of HSCs that was inhibited by diphenylene iodonium pretreatment. Phosphorylation of the mitogen-activated protein kinase (MAPK) family constitutes a signal transduction pathway of cell proliferation. Our data demonstrate that NAD(P)H oxidase-derived ROS induce HSC proliferation mainly through the phosphorylation of p38 MAPK. Moreover, an in vivo hepatic fibrosis model also supported the critical role of NAD(P)H oxidase in the activation and proliferation of HSCs. In conclusion, NAD(P)H oxidase is expressed in HSCs and produces ROS via activation of NAD(P)H oxidase in response to PDGF-BB. ROS further induce HSC proliferation through the phosphorylation of p38 MAPK.

Animals↗

PubMed1998

Acute and chronic ethanol increases reactive oxygen species generation and decreases viability in fresh, isolated rat hepatocytes.

Although reactive oxygen species (ROS) have been implicated in the etiology of alcohol-induced liver disease, neither their relative contribution to cell death nor the cellular mechanisms mediating their formation are known. The purpose of this study was to test the hypothesis that acute and chronic ethanol exposure enhances the mitochondrial generation of ROS in fresh, isolated hepatocytes. Acute ethanol exposure stimulated ROS production, increased the cellular NADH/NAD+ ratio, and decreased hepatocyte viability slightly, which was prevented by pretreatment with 4-methylpyrazole (4-MP), an inhibitor of alcohol dehydrogenase. Similarly, xylitol, an NADH-generating compound, enhanced hepatocyte ROS production and decreased viability. Incubation with pyruvate, an NADH-oxidizing compound, and cyanamide, an inhibitor of aldehyde dehydrogenase, significantly decreased ROS levels in acute ethanol-treated hepatocytes. Chronic ethanol consumption produced a sixfold increase in hepatocyte ROS production compared with levels measured in controls. Hepatocytes from ethanol-fed rats were less viable compared with controls, e.g., viability was 68% +/- 2% (ethanol) versus 83% +/- 1% (control) after 60 minutes of incubation. Antimycin A increased ROS production and decreased cell viability; however, the toxic effect of antimycin A was more pronounced in ethanol-fed hepatocytes. These results suggest that acute and chronic ethanol exposure exacerbates mitochondrial ROS production, contributing to cell death.

Alcohol Dehydrogenase↗

PubMed2007

Differential involvement of reactive oxygen species in apoptosis induced by two classes of selenium compounds in human prostate cancer cells.

Selenium is a promising chemopreventive agent for prostate cancer, possibly via an induction of apoptosis. Earlier studies have shown that selenite induces DNA single strand breaks (SSBs), reactive oxygen species (ROS), p53 Ser-15 phosphorylation and caspase-dependent and -independent apoptosis, whereas a methylselenol precursor methylseleninic acid (MSeA) induces caspase-mediated apoptosis regardless of p53 status. Here we address three main questions: What types of ROS are induced by selenite vs. MSeA in LNCaP (p53 wild type, androgen-responsive) and DU145 (mutant p53, androgen-independent) prostate cancer cells? Does ROS generation depend on androgen signaling? What are the relationships among ROS, DNA SSBs, p53 and caspases? We show that selenite (5 microM) induced superoxide and hydrogen peroxide in LNCaP cells much more than in DU145 cells and the ROS generation was not affected by physiological androgen stimulation. MSeA (10 microM) induced apoptosis without either type of ROS in both cell lines. In LNCaP cells, we established superoxide as a primary mediator for selenite-induced DNA SSBs, p53 activation and caspase-mediated apoptosis. Furthermore a p53-dominant negative mutant attenuated selenite-induced ROS, leading to a proportionate protection against apoptosis. The results support the p53-mitochondria axis in a feedback loop for sustaining superoxide production to lead to efficient caspase-mediated apoptosis by selenite. In contrast, caspase-mediated apoptosis induced by MSeA does not involve ROS induction. Since p53 is frequently mutated or deleted in prostate cancer and many other cancers, our results suggest that genotoxic vs. nongenotoxic classes of selenium may exert differential apoptosis efficacy depending on the p53 status of the cancer cells.

Acetylcysteine↗

PubMed2002

Role of reactive oxygen species in hippocampal long-term potentiation: contributory or inhibitory?

Reactive oxygen species (ROS) typically are characterized as molecules involved in neurotoxicity and neurodegeneration. However, recent evidence from both neuronal and nonneuronal cells suggests that ROS also function as small messenger molecules that are normal components of signal transduction cascades during physiological processes. Consistent with this idea, ROS have been shown to be critical for hippocampal long-term potentiation (LTP), a form of synaptic plasticity widely studied as a cellular substrate for learning and memory. On the other hand, ROS also have been shown to be involved in aging-related impairment of LTP. This review discusses the evidence supporting the notion that ROS both contribute to normal LTP and are involved in age-related impairment of LTP. We also discuss possible sources that might be responsible for the production of ROS after the induction of LTP. Finally, we propose a functional ROS continuum to help explain this dichotomy of ROS function in hippocampal LTP.

Animals↗

PubMed2004

Several signaling pathways are involved in the control of cattle oocyte maturation.

The main limit of in vitro production of domestic mammal embryos comes from the low capacity of in vitro matured oocytes to develop after fertilization. As soon as they are separated from follicular environment, oocytes spontaneously resume meiosis without completion of their terminal differentiation. Roscovitine (ROS), an inhibitor of M-phase promoting factor (MPF) kinase activity reversibly blocks the meiotic resumption in vitro. However, in cattle maturing oocytes several cellular events such as protein synthesis and phosphorylation, chromatin condensation and nuclear envelope folding escape ROS inhibition suggesting the alternative pathways in oocyte maturation. We compared the level of synthesis and phosphorylation of several protein kinases during bovine cumulus oocyte complex (COC) maturation in vitro in the presence or not of epidermal growth factor (EGF) and ROS. We showed that during the EGF-stimulated maturation, ROS neither affected the decrease of EGF receptor (EGFR) nor did inhibit totally its phosphorylation in cumulus cells and also did not totally eliminate tyrosine phosphorylation in oocytes. However, ROS did inhibit the Phosphoinositide 3-kinase (PI3) activity when oocytes mature without EGF. Accumulation of Akt/PKB (protein kinase B), JNK1/2 (jun N-terminal kinases) and Aurora-A in oocytes during maturation was not affected by ROS. However, the phosphorylation of Akt but not JNKs was diminished in ROS-treated oocytes. Thus, PI3 kinase/Akt, JNK1/2 and Aurora-A are likely to be involved in the regulation of bovine oocyte maturation and some of these pathways seem to be independent to MPF activity and meiotic resumption. This complex regulation may explain the partial meiotic arrest of ROS-treated oocytes and the accelerated maturation observed after such treatment.

Animals↗

PubMed2004

Reactive oxygen species may influence the heat shock response and stress tolerance in the yeast Saccharomyces cerevisiae.

Moderate levels of reactive oxygen species (ROS) have been implicated as second messengers in a number of biochemical pathways, and in animal cells have been associated with the activation of the heat shock response (HSR). Here, using an intracellular probe, we demonstrate that differential accumulation of ROS in the yeast Saccharomyces cerevisiae is strongly associated with differential induction of an HS reporter gene over a range of heat shock temperatures. There was a good correlation between cellular ROS levels and the levels of HS-induced reporter gene expression between 37 degrees C and 44 degrees C, both reaching maximal values at 41 degrees C. Furthermore, the addition of 150 microM H2O2 to the yeast cells during heat treatment resulted in a 3 degrees C decrease in the temperature required for maximal induction of the HS expression vector--an increased HS sensitivity that corresponded to a concomitant increase in ROS levels at these lower HS temperatures. Conversely, cells treated with 10 mM of the antioxidant ascorbic acid required a temperature that was 2 degrees C above that required in untreated controls for maximal induction of the HS expression vector. This decreased HS sensitivity corresponded to a decrease in ROS levels at these higher HS temperatures. Finally, cell viability assays reveal that intrinsic thermotolerance remains high in control cells despite concomitant decreases in HS-reporter gene expression and ROS accumulation between 41 degrees C and 44 degrees C. We conclude that the sensitivity of the yeast HSR is strongly associated with ROS accumulation, and suggest that ROS-mediated signalling ensures cooperation between the HS and the antioxidant responses.

Acclimatization↗

PubMed1994

Kinetic studies on phagocytosis and lysosomal digestion of rod outer segments by human retinal pigment epithelial cells in vitro.

Using novel methodology, this study describes the kinetics of rod outer segment (ROS) phagocytosis and digestion by human retinal pigment epithelial (RPE) cells in vitro and examines the effect of certain lysosomal enzyme inhibitors on ROS digestion in these cells. Human RPE cells displayed saturation of phagocytosis with respect to both ROS concentration and time. While surface-binding and ingestion phases of ROS phagocytosis saturated after 24-36 h, the rate of ROS digestion reached a maximal level within 24 h. Increasing the concentration of zinc in the culture medium from 1.9 to 100 microM had no significant effect on ROS digestion. The effects of swainsonine (an alpha-mannosidase inhibitor), pepstatin (an aspartic protease inhibitor), and leupeptin (a cysteine protease inhibitor) were also examined. At 6 h, ROS digestion was reduced 27.3 +/- 15.3% by swainsonine, 69.4 +/- 20.9% by pepstatin, and 77.0 +/- 14.4% by leupeptin. The effect of these inhibitors declined with increasing time. This study is the first to demonstrate the functional importance of cysteine and aspartic proteases in the digestion of ROS by RPE cells in vitro.

Animals↗

PubMed1993

Metabolism in frog retinal pigment epithelium of docosahexaenoic and arachidonic acids derived from rod outer segment membranes.

Frog photoreceptor cells shed about 10% of their rod outer segments (ROS) every 4th day. Packets of these membranes are phagocytized and digested by retinal pigment epithelial (RPE) cells. Large amounts of lipids must be processed daily, especially docosahexaenoic acid (22:6n-3, DHA), the major fatty acid of these membranes. To study the metabolism of ROS lipids in RPE cells, RPE-eyecups were incubated with [3H]DHA-, [3H]arachidonic acid (AA)-, or [2-3H]glycerol-labeled ROS membranes for 2 hr, followed by a chase for up to 8 hr. Lipid extracts of RPE cells and incubation media were resolved into classes and quantitated for radioactivity. In RPE cells, the relative proportion of DHA and AA label in triglycerides (TG) increased dramatically with incubation time, although the substrate ROS membranes did not contain labeled TG. Other RPE lipids showed prominent reductions or relative little change. The percentage of radioactivity in free fatty acids (FFA) was low (< 3%) in RPE cells. In the chase media, the majority (60-80%) of DHA and AA label was found in FFA, with little radioactivity in TG or phospholipids. When RPE cells were incubated with [3H]glycerol-labeled ROS membranes which contained 22% of the label in TG, the most rapid reduction in relative radioactivity appeared in TG. We conclude that DHA and AA are released from phagocytized ROS membranes and are rapidly incorporated into RPE cellular lipids, primarily TG. This lipid class is very active metabolically, since TG derived from ROS are rapidly hydrolysed. Free DHA and AA of ROS origin are released from RPE cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1999

Antioxidant activity of retinol, glutathione, and taurine in bovine photoreceptor cell membranes.

The antioxidant activities of compounds endogenous to mammalian rod outer segments (ROS) were investigated in vitro by measuring the oxidative loss of polyunsaturated fatty acids (PUFA's) from the membranes of intact ROS and from liposomes made from ROS phospholipids (PL) to which lipid soluble compounds had been added. The membranes were exposed to the water-soluble oxidant 2, 2'-azobis(2-amidinopropane) dihydrochloride (AAPH). Retinol protected PUFA's in ROS liposome PL's, whereas retinaldehyde promoted lipid peroxidation. When isolated ROS were stimulated to produce endogenous retinol, PUFA loss was inhibited by up to 17%. These findings suggest an antioxidant function for the enzymatic reduction of retinaldehyde to retinol during the visual cycle. Water-soluble antioxidants, taurine and reduced glutathione (GSH), were investigated individually and in combination with retinol in ROS PL liposomes. GSH protected PUFA's in ROS PL liposomes. Taurine alone showed little antioxidant activity, but in combination with retinol it protected lipids twice as much as retinol alone. These results support previous findings that taurine protects ROS lipids during exposure to cyclic light.

Animals↗

PubMed1997

Significant levels of oxidants are generated by isolated cardiomyocytes during ischemia prior to reperfusion.

Oxidants such as reactive oxygen species (ROS) have been shown to participate in myocardial ischemia/reperfusion injury. While many studies report a burst of ROS at reperfusion, few reports have presented evidence of significant ROS generation during ischemia. Our previous studies of cultured cardiomyocytes indicated that antioxidants are most effective when given prior to reperfusion during ischemia. Therefore, we hypothesized that significant ROS generation may occur during ischemia prior to reperfusion. We tested this in a perfused isolated cardiomyocyte system (i.e. without neutrophils, endothelial cells, or xanthine/xanthine oxidase) during simulated ischemia/reperfusion while measuring oxidant generation using intracellular fluorescent probes. During ischemia, the ROS probes dihydroethidium and 2',7'-dichlorofluorescin were significantly oxidized, suggesting superoxide and H2O2 generation. At reperfusion following 1 h ischemia, these probes suggested a further burst of H2O2 and hydroxyl radicals. The antioxidants 2-mercaptopropionyl glycine and 1,10-phenanthroline used during ischemia attenuated oxidant generation, increased cell viability, and improved return of contraction after ischemia. To further evaluate the relationship between residual O2 and ROS generation, we administered O2 scavengers during ischemia and measured corresponding changes in oxidant generation, cell viability and contraction during reperfusion. Enzymatic scavenging of residual O2 during ischemia (reducing PO2 from 3.5 to 2.5 tau) paradoxically improved subsequent viability and contraction. These results indicate that cultured cardiomyocytes generate significant ROS during ischemia. This ROS generation is related to residual O2 present during ischemia and contributes significantly to the cellular injury seen at reperfusion.

Animals↗

PubMed2001

Bilirubin impairs bactericidal activity of neutrophils through an antioxidant mechanism in vitro.

BACKGROUND: Liver failure accompanied by hyperbilirubinemia after major hepatic resection is profoundly associated with septic complications. Although the immune dysfunction in cholestasis has been intensively investigated, the contribution of increased serum bilirubin to the impaired resistance to bacterial infection remains to be elucidated. Because bilirubin possesses an antioxidant activity, we hypothesized that bilirubin may scavenge reactive oxygen species (ROS) produced by neutrophils and consequently impair neutrophil bacterial killing. To address this, we evaluated the effects of bilirubin on the bactericidal activity of ROS or of neutrophils in vitro. MATERIALS AND METHODS: The antioxidant activity of bilirubin was determined using an ROS-sensitive fluorophore, dichlorofluorescin diacetate (DCFH-DA). Bilirubin concentration in the buffer solution was monitored spectorophotometrically after incubation with ROS. The effect of bilirubin on killing of Escherichia coli by ROS or by isolated human neutrophils was determined by counting the viable E. coli after incubation on nutrient agar. RESULTS: The bilirubin concentration in the buffer solution was decreased by the addition of hydrogen peroxide, especially in the presence of peroxidase or ferrous iron. DCFH-DA oxidation by ROS or activated neutrophils was inhibited by bilirubin in a dose-dependent manner. The bactericidal activity of ROS or of isolated neutrophils was significantly attenuated by bilirubin. CONCLUSIONS: Bilirubin impairs bactericidal activity of neutrophils through scavenging ROS. Increased levels of serum bilirubin may well be responsible for the impaired bacterial clearance in patients with hyperbilirubinemia.

Antioxidants↗

PubMed1985

Ca2+ buffer sites in intact bovine rod outer segments: introduction to a novel optical probe to measure ionic permeabilities in suspensions of small particles.

The nature of the Ca2+ buffer sites in intact rod outer segments isolated from bovine retinas (ROS) was investigated. The predominant Ca2+ buffer in intact ROS was found to be negatively charged groups confined to the surface of the disk membranes. Accordingly, Ca2+ buffering in ROS was strongly influenced by the electrostatic surface potential. The concentration of Ca2+ buffer sites was about 30 mM, 80% of which were located at the membrane surface in the intradiskal space. A comparison with observations in model systems suggests that phosphatidylserine is the major Ca2+ buffer site in ROS. Protons and alkali cations could replace Ca2+ as mobile counterions for the fixed negatively charged groups. At physiological ionic strength, the total number of these diffusible, but osmotically inactive, counterions was as large as the number of osmotically active cations in ROS. The surface potential is dependent on the concentration of cations in ROS and can be measured with the optical dye neutral red. Addition of cations to the external solution led to the release of the internally bound dye as the cations crossed the outer membrane. The chemical and spectral properties of the dye enable its use as a real-time indicator of cation transport across the outer envelope of small particles in suspension. In this study, the dye method is illustrated by the use of well-defined ionophores in intact ROS and in liposomes. In the companion paper this method is used to describe the cation permeabilities native to ROS.

Animals↗

PubMed1986

Formation of calcifying matrix by osteosarcoma cells in diffusion chambers in vivo.

The potential of clonal rat osteosarcoma (ROS) cell lines to form mineralized matrices was assessed in diffusion chambers in vivo. Diffusion chambers were inoculated with osteoblastic (ROS 17/2 and its subclone ROS 17/2.8) and non-osteoblastic (ROS 24/1) clonal lines and implanted either intraperitoneally into athymic mice or subcutaneously into syngeneic ACI rats. Control chamber cultures of rabbit marrow or spleen cells were also incubated in athymic mice. Light and electron microscopy of chambers with ROS 17/2 and ROS 17/2.8 cells revealed production of mineralized matrices typical of osteosarcoma and characterized by abundance of collagen fibrils and associated mineralizing nodules. ROS 24/1 cells produced similar collagenous matrices, but these were devoid of mineral. The present experiments, carried out independently in two different laboratories, demonstrate the potential of ROS cells to produce a mineralized matrix. This corroborates previous studies on other osteoblastic features of these cell lines.

Animals↗

PubMed2004

Reactive oxygen species and EGR-1 gene expression in surgical postoperative peritoneal adhesions.

Postoperative peritoneal adhesions are common and serious complications of general abdominal and gynecological surgery that can lead to chronic abdominal pain, small-bowel obstruction and infertility. The specific pathophysiology of peritoneal adhesions remains elusive and current treatment is relegated to prevention through meticulous surgical technique and protective physical barriers, gels and solutions. We have reported that reactive oxygen species (ROS), generated by phagocytic cells at the site of tissue injury, serve as major signaling molecules regulating the expression of vascular endothelial growth factor (VEGF) and subsequent wound repair. We hypothesized that peritoneal adhesions are a product of over-healing surgical wounds and that, like in wound healing, ROS are implicated in their pathogenesis. We examined the presence of footprints of ROS and the ROS-inducible angiogenic factor VEGF in human adhesion tissue. An experimental model of peritoneal adhesion was established in rodents to study of the dynamics of ROS-induced gene expression during de novo adhesion tissue formation. Immunohistochemical analysis demonstrated presence of ROS/oxidant and macrophages in human peritoneal tissue. The presence of ROS and ROS-sensitive transcription factor EGR-1 was also evident in an experimental rodent peritoneal adhesion model. Along with ROS, VEGF, and a large number of mature and immature CD31/vWF positive blood vessels were present in the adhesion tissue. These observations are not consistent with the contention that adhesions are non-functional scar tissue. The newly developed rodent model of adhesion may present a useful approach to reproducibly and objectively study molecular mechanisms underlying the dynamic process of de novo adhesion tissue formation.

Animals↗

PubMed2004

In vivo and in vitro evidences that carotenoids could modulate the neutrophil respiratory burst during dietary manipulation.

BACKGROUND: The primary role of polymorphonuclear neutrophils (PMNs) is to destroy pathogenic microorganisms after phagocytosis by producing reactive oxygen species (ROS) and toxic molecules. However, PMNs produce sufficient amounts of ROS during an oxidative burst to be autotoxic and detrimental to their own functions and to possibly cause DNA damage, protein and lipid oxidation and cell membrane destructuration. OBJECTIVE: The aim of this study was to investigate in vivo the role of the antioxidant capacities of carotenoids in modulating ROS content in PMNs during oxidative burst. Moreover to investigate the direct or indirect effect of carotenoids, the modification of PMN ROS content was explored after in vitro supplementation with beta-carotene or lycopene, chosen taking account of their vitamin A and no vitamin A precursor effect, respectively. DESIGN: In vivo study: Venous blood was collected from 10 healthy male volunteers and ROS production from phorbol myristate acetate (PMA)-stimulated PMNs was determined, by flow cytometry using the fluorescent dye dihydrorhodamine 123, at baseline, after 3 weeks of carotenoid depletion (carotenoid intake limited to 25% of usual intake) and after 5 weeks of carotenoid repletion (30 mg beta-carotene, 15 mg lycopene and 9 mg lutein per day). In vitro study: ROS content in PMA-stimulated PMNs isolated from carotenoid depleted subjects and controls was quantified after an in vitro enrichment with beta-carotene (1 micromol/L) or lycopene (0.3 micromol/L). RESULTS: In vivo carotenoid depletion increased PMN H2O2 content after PMA activation by 38% (p < 0.05 vs baseline),while supplementation for 5 weeks restored basal H2O2 generation (p < 0.05 vs depletion). Although H2O2 measurement in PMNs from non-depleted subjects was not affected by an in vitro supply with beta-carotene or lycopene, a significant decrease in H2O2 content by 78.9 % and 81.2%, respectively, was observed in PMNs from carotenoid depleted subjects (p < 0.01 vs depleted control subjects). CONCLUSIONS: The carotenoid ROS quenching capacities control both in vivo and in vitro the PMNs ROS generation and probably protect these cells against DNA, membrane lipid and protein damages during oxidative burst. Moreover, these effects appear independent from the metabolic conversion of carotenoids to vitamin A.

Antioxidants↗

PubMed2005

Ornithine decarboxylase prevents methotrexate-induced apoptosis by reducing intracellular reactive oxygen species production.

Methotrexate (MTX), a folate antagonist, was developed for the treatment of malignancies, and is currently used in rheumatoid arthritis (RA) and other chronic inflammatory disorders. It has been proven in short-term and long-term prospective studies that low doses of MTX (0.75 mg/Kg/week) are effective in controlling the inflammatory manifestations of RA. Low-concentrations of MTX achieve apoptosis and clonal deletion of activated peripheral T cells. One of the mechanisms of the anti-inflammatory and immunosuppressive effects may be the production of reactive oxygen species (ROS). However, the drug resistance of MTX in malignancies remains poorly understood. Ornithine decarboxylase (ODC) plays an important role in diverse biological functions, including cell development, differentiation, transformation, growth and apoptosis. In our previous studies, ODC overexpression was shown to prevent TNFalpha-induced apoptosis via reducing ROS. Here, we also investigated one mechanism of MTX-induced apoptosis and of drug resistance as to the anti-apoptotic effects of ODC during MTX treatment. We found MTX could induce caspase-dependent apoptosis and promote ROS generation together with disrupting the mitochondrial membrane potential (DeltaPsim) of HL-60 and Jurkat T cells. Putrescine and ROS scavengers could reduce MTX-induced apoptosis, which leads to the loss of DeltaPsim, through reducing intracellular ROS. Overexpression of ODC in parental cells had the same effects as putrescine and the ROS scavengers. Moreover, ODC overexpression prevented the decline of Bcl-2 that maintains DeltaPsim, the cytochrome c release and activations of caspase 9 and 3 following MTX treatment. The results demonstrate that MTX-induced apoptosis is ROS-dependent and occurs along a mitochondria-mediated pathway. Overexpressed ODC cells are resistant to MTX-induced apoptosis by reducing intracellular ROS production.

Apoptosis↗

PubMed2005

Reactive oxygen and nitrogen species: friends or foes?

Chemical and physiological functions of molecular oxygen and reactive oxygen species (ROS) and existing equilibrium between pools of pro-oxidants and anti-oxidants providing steady state ROS level vital for normal mitochondrial and cell functioning are reviewed. The presence of intracellular oxygen and ROS sensors is postulated and few candidates for this role are suggested. Possible involvement of ROS in the process of fragmentation of mitochondrial reticulum made of long mitochondrial filaments serving in the cell as "electric cables", as well as the role of ROS in apoptosis and programmed mitochondrial destruction (mitoptosis) are reviewed. The critical role of ROS in destructive processes under ischemia/reoxygenation and ischemic preconditioning is discussed. Mitochondrial permeability transition gets special consideration as a possible component of the apoptotic cascade, resulting in excessive "ROS-induced ROS release".

Animals↗