The effect of desferrioxamine on peroxynitrite-induced oxidative damage in erythrocytes

Vitamins C and E alone and in combination partly protect against chronic ethanol-induced toxicity in rat erythrocytes

Oxidative stress is part of the mechanisms involved in ethanol toxicity. We investigated effects of vitamins C (VC), E (VE) and the combination of VC+VE on chronic ethanol-induced toxicity in rat erythrocytes. The following groups were treated for 30 days: control (C), VC (200 mg/kg), VE (200 mg/kg), VC (200 mg/kg) + VE (200 mg/kg), ethanol 4 g/kg, ethanol + VC, ethanol + VE and ethanol + VC + VE. The doses of vitamins and ethanol were selected for per kilogram of animal's body weight. Blood samples collected at the end of treatments were analyzed for erythrocyte osmotic fragility and plasma scavenging activity. The washed erythrocytes were used to determine superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and malondialdeyde (MDA). Ethanol induced erythrocyte fragility (p < 0.001) and increased lipid peroxidation (p < 0.001) in rat erythrocytes. Furthermore, there were significant decreases in plasma scavenging (p < 0.001), SOD (p < 0.001), CAT (p < 0.01) and GPx (p < 0.001) activities in erythrocytes of ethanol-treated animals. Although VC or VE alone restored all of ethanol-induced disturbances to near normal (p > 0.05) but there were still significant differences compared to control animals. Combination therapy completely corrected ethanol-induced erythrocyte fragility, lipid peroxidation and prooxidant/antioxidant imbalance. We showed the beneficial effects of VC and VE combination in decreasing erythrocyte fragility and lipid peroxidation in both ethanol and control groups. Therefore this combination treatment may provide a new potential alternative for prevention of ethanol toxicity which deserves consideration and further examination.

Neonatal, placental, and umbilical cord blood parameters in pregnant women residing in areas with intensive pesticide application

In rural populations, the proximity to areas with intensive pesticide application represents a risk factor of xenobiotic exposure. Here, we investigated whether newborns born to mothers residing in an area with intensive pesticide application show alterations in placental and neonatal morphometric standards, umbilical cord blood (UCB) biochemical parameters, and/or biomarkers related to oxidative stress and oxidative damage. Samples were collected from 151 healthy pregnant women residing in a rural area (rural group; RG) during the pesticide spraying (SS) and nonspraying (NSS) seasons, as well as from women from an urban population (control group; CG), and grouped according to the delivery type (vaginal or cesarean). In the vaginal delivery group, the placental weight and placental index were higher in the RG groups than in the CG (p = 0.01), whereas in the cesarean delivery group, newborn weight was lower in the RG-SS group than in the CG. In the RG-SS group, UCB erythrocyte osmotic fragility and the DNA damage index (DI) were higher, and superoxide dismutase (SOD) activity was lower than in the RG-NSS group. Acetylcholinesterase and SOD activities were found to be inversely correlated with the DI.

Protective effects of pomegranate peel against hematotoxicity, chromosomal aberrations, and genotoxicity induced by barium chloride in adult rats

CONTEXT

Pomegranate peel (PP) has health benefits including antibacterial, antioxidant, anti-inflammatory, and antimutagenic properties.

OBJECTIVE

This study investigated the biochemical composition and protective effects of PP against hematotoxicity and genotoxicity induced by barium chloride (BaCl2) in adult rats.

MATERIALS AND METHODS

Adult Wistar rats were divided into four groups of six each: control, barium (67 ppm via drinking water), PP (5% via diet), and their combination during 21 d. Oxidative stress was determined by MDA, AOPP, and antioxidant status: CAT, GPx, GSH, Vit C. Osmotic fragility (OF), chromosomal aberrations (CAs), and micronucleus (MN) assays were also studied.

RESULTS

PP showed a rich composition of antioxidant compounds. DPPH test found IC50 value= 5.3 μg/mL and a high polysaccharides content (315 ± 5 mg/g of extract). In vivo study showed a decrease in red blood cells (70%) and platelet counts (46%), hemoglobin content (8%), hematocrit percent (7%), and an 80% increase of white blood cells in Ba-treated rats. A reduction in antioxidant status: catalase, glutathione peroxidase activities, glutathione, and vitamin C levels by 31, 21, 28, and 29%, respectively, and an increase in MDA (46%) and AOPP levels (72%) were also observed compared with controls. BaCl2-treatment showed a significant increase in the frequencies of total chromosomal aberrations with abnormal metaphases and micronucleus in bone-marrow cells. Oxidative stress induced by BaCl2 might be the major cause for chromosomal abnormalities leading to DNA damage.

DISCUSSION AND CONCLUSION

A decrease in hematotoxic and genotoxic effects induced by PP is due to its powerful antioxidant capacity.

The effect of maximum storage on iron status, oxidative stress and antioxidant protection in paediatric packed cell units. Blood Transfus. 2013;11:419-425. [PMID: 23058860 DOI: 10.2450/2012.0046-12]

BACKGROUND

Premature babies may receive multiple transfusions during the first weeks of their life. Strong associations exist between the receipt of blood transfusions and the development of the major consequences of prematurity such as retinopathy and chronic lung disease. The possible physiological link between the receipt of blood and disease is unclear, but iron-induced oxidative damage and/or bacterial colonisation would promote these conditions. Premature babies are poorly equipped to deal with any increases in iron and oxidative load that they may acquire via blood transfusions. To determine whether there are any relationships between these factors, we studied iron and oxidative status of just expired (i.e. 36 days old) paediatric red blood cell (RBC) packs.

MATERIALS AND METHODS

Just expired paediatric RBC packs were obtained from the local blood bank. The extracellular medium surrounding the RBC was separated by centrifugation and the following parameters measured: total iron concentration, total iron binding capacity, non-transferrin-bound iron [NTBI], haemoglobin, total and reduced ascorbate, and malondialdehyde concentration.

RESULTS

The extracellular fluid of the paediatric packs (n =13) was rich in iron, a high percentage of which (36%) was present as potentially toxic NTBI. It was highly redox active with limited antioxidant protection and iron-binding capacity.

DISCUSSION

The extracellular medium surrounding packed RBC could potentially be toxic if administered to patients with limited iron sequestering and antioxidant capacity, such as premature babies. Further studies are required to determine at what point during storage these changes become potentially harmful so that clinical studies can examine the optimal storage time for blood destined for premature babies.

Ameliorative effect of Opuntia ficus indica juice on ethanol-induced oxidative stress in rat erythrocytes

The aim of the present study was to investigate the efficacy of Opuntia ficus indica f. inermis fruit juice (OFIj) on reversing oxidative damages induced by chronic ethanol intake in rat erythrocytes. OFIj was firstly analyzed with HPLC for phenolic and flavonoids content. Secondly, 40 adult male Wistar rats were equally divided into five groups and treated for 90 days as follows: control (C), ethanol-only 3 g/kg body weight (b.w) (E), low dose of OFIj 2 ml/100 g b.w+ethanol (Ldj+E), high dose of OFIj 4 ml/100 g b.w+ethanol (Hdj+E), and only a high dose of OFIj 4 ml/100g b.w (Hdj). HPLC analysis indicated high concentrations of phenolic acids and flavonoids in OFIj. Ethanol treatment markedly decreased the activities of erythrocyte superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), and the level of reduced glutathione (GSH). Changes in the erythrocyte's antioxidant ability were accompanied by enhanced oxidative modification of lipids (increase of malondialdeyde level) and proteins (increase in carbonyl groups). Interestingly, pre-administration of either 2 ml/100 g b.w or 4 ml/100 g b.w of OFIj to ethanol-intoxicated rats significantly reversed decreases in enzymatic as well as non enzymatic antioxidants parameters in erythrocytes. Also, the administration of OFIj significantly protected lipids and proteins against ethanol-induced oxidative modifications in rat erythrocytes. The beneficial effect of OFIj can result from the inhibition of ethanol-induced free radicals chain reactions in rat erythrocytes or from the enhancement of the endogenous antioxidants activities.

Phosphorylation of SMC1 by ATR is required for desferrioxamine (DFO)-induced apoptosis

DNA damage signaling pathways are initiated in response to chemical reagents and radiation damage, as well as in response to hypoxia. It is implicated that structural maintenance of chromosomes 1 (SMC1) is not only a component of the cohesion complex but also facilitates the activation of DNA damage checkpoint proteins. Here, we studied the mechanism of DNA damage checkpoint activated by ATR–SMC1 pathway when cells are treated with desferrioxamine (DFO), a hypoxia-mimetic reagent. We show that DFO treatment induces phosphorylation of SMC1 at Ser966, NBS1 at Ser343, Chk1 at Ser317, Chk2 at Thr68, and p53 at Ser15. Among these sites, phosphorylation of SMC1, NBS1, and Chk1 by DFO are mediated by ATR as it is greatly reduced in both ATR-deficient human fibroblasts and HCT116 human colon cancer cells in which ATR is heterozygously mutated, whereas these proteins are phosphorylated in cells deficient for ATM and DNA-PKcs. DFO-induced apoptosis is decreased in ATR-mutant HCT116 cells, although p53 is normally activated in those cells. Expression of SMC1 S966A in which Ser966 is substituted to Ala attenuates apoptosis and phosphorylation of Chk1 at Ser317 after DFO treatment, although levels of HIF1α are not significantly changed. These results suggest that DFO induces apoptosis through the ATR–SMC1 arm of the pathway.

Desferrioxamine (DFX) induces apoptosis through the p38-caspase8-Bid-Bax pathway in PHA-stimulated human lymphocytes

Desferrioxamine (DFX) induces apoptosis in human lymphocytes, although the mechanism leading to cell death is unclear. Therefore, we investigated the signaling pathways implicated in DFX-induced apoptosis in lymphocytes. DFX treatment activated caspase-9, caspase-3, and caspase-8. DFX-induced apoptosis was inhibited by both z-IETD-fmk and z-DEVD-fmk. DFX treatment also enhanced caspase-8 activity, Bid cleavage, and the conformational activation of Bax. DFX treatment activated two MAPKs, p38 and JNK, and induced the phosphorylation of two proteins in the p38 pathway, MKK3 and MKK6. DFX treatment also increased the phosphorylation of two downstream targets of p38, ATF-2 and MAPKAPK2, indicating that DFX promotes p38 activity. In addition, the selective p38 inhibitor SB203580 suppressed DFX-induced apoptosis and caspase-8 activation, whereas the JNK inhibitor, SP600125, and the ERK inhibitor, PD98059, had no effect. Our results suggest that DFX-induced apoptosis is mediated by the p38 pathway and a caspase-8-dependent Bid-Bax pathway in human lymphocytes.

Effects of trichlorfon on malondialdehyde and antioxidant system in human erythrocytes

Organophosphorus insecticides may induce oxidative stress leading to generation of free radicals and alteration in antioxidant system. The aim of this study was to examine the potency of trichlorfon, an organophosphate insecticide, to induce oxidative stress response in human erythrocytes in vitro. For this purpose trichlorfon solutions in different concentrations and erythrocyte solutions were incubated at 37 degrees C for 60 min. At the end of the incubation time, malondialdehyde (MDA), an end product of lipid peroxidation, total glutathione, reduced glutathione (GSH) levels, activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) enzymes were determined by spectrophotometric methods. Trichlorfon increased MDA formation depended on the concentration. On the other hand, decreases in the GSH-Px activity, GSH levels and increases in the total glutathione levels, SOD and CAT activities were seen in the studied concentrations. The present findings indicate that the in vitro toxicity of trichlorfon may be associated with oxidative stress.

Desferrioxamine (DFX) has genotoxic effects on cultured human lymphocytes and induces the p53-mediated damage response

Desferrioxamine (DFX), which is an iron chelator, mimics hypoxia by enhancing HIF1-alpha accumulation and upregulating inflammatory mediators. DFX is usually beneficial, with preventive effects related primarily to its ability to scavenge reactive oxygen species. However, toxic effects on skeletal and ocular organs have been reported. The cytokinesis block micronucleus test and alkaline single-cell gel (Comet) assay were used to evaluate the genotoxic effects of DFX on human blood lymphocytes. Cultured human lymphocytes treated with 130microM DFX for various periods of time showed significant differences in the incidence of micronucleated binucleate cells, as well as in the length and moment of the comet tail. Western blot analysis using antibodies to proteins involved in the p53-mediated response to DNA damage revealed that p53 was accumulated and DNA damage checkpoint kinases were activated in lymphocytes treated with DFX. On the other hand, the p53 downstream target proteins p21 and bax were not affected, which indicates that DFX does not promote the transactivational activity of p53. Apoptosis assays demonstrated DFX-induced apoptosis of lymphocytes via the caspase cascade. The observed increase in the sub-G1 fraction and enhanced caspase-3 activity indicate that DFX can promote apoptosis in human lymphocytes, and these results were confirmed by protein immunoblot analysis. As apoptotic cell death is preceded by the collapse of the mitochondrial membrane potential, we also measured the mitochondrial membrane potential (Deltapsi(m)) using DiOC6, which is a fluorescent membrane potential probe. The fluorescence intensity of DiOC6 in lymphocytes was significantly reduced in a time-dependent manner after DFX treatment. Taken together, these results indicate that DFX activates p53-mediated checkpoint signals and induces apoptosis via mitochondrial damage in human peripheral blood lymphocytes.

Metal chelators react also with reactive oxygen and nitrogen species

Popular chelators (desferrioxamine, SIH, EDTA, EGTA, DTPA, and NTA) were demonstrated to have antioxidant properties, being able to reduce ABTS radical cation and react with peroxyl radicals, peroxynitrite, and hypochlorite. Desferrioxamine and SIH were most potent antioxidants in all cases. These results point to the necessity of a careful interpretation of experiments in which the inhibition of free radical reactions by antioxidants is used as a proof of involvement of metal ions in a reaction.

Iron chelator induces THP-1 cell differentiation potentially by modulating intracellular glutathione levels

Iron chelators have been implicated to modulate certain inflammatory mediators and regulate inflammatory processes. Here we report that iron chelator deferoxamine (DFO) induces differentiation of monocytic THP-1 cells into functional macrophages. DFO rapidly phosphorylated both extracellular signal-regulated kinase (ERK) and p38 kinase. Blockade of ERK signaling by the MEK1/2 inhibitor PD098059 abolished DFO-induced class A scavenger receptor (SR-A) expression and phagocytic activity, indicating that ERK cascades mediate the induction of THP-1 differentiation. In contrast, in cells treated with the p38 inhibitor SB203580 or transfected with the dominant-negative variant of p38 kinase, DFO-mediated ERK activation became more prominent, and the induction of SR-A expression and phagocytic activity were significantly increased. Interestingly, differentiation by DFO was associated with decrease in cellular glutathione (GSH) level. Both MAPK inhibitors did not influence the GSH level; however, treatment with ferric citrate (Fe3+) or N-acetyl-cysteine, a major precursor of GSH, markedly recovered GSH level to a normal extent, along with the significant decrease of differentiation. Collectively, these results indicate that oxidative stress by DFO and the resulting activation of ERK cascade play dominant roles in the process of THP-1 differentiation, while p38 acts as a negative signal transmitter.

A comparative study of the effects of molsidomine and 3-morpholinosydnonimine on the redox status of rat erythrocytes and reticulocytes

After enzymic biotransformation, molsidomine (MO) acts via the metabolite 3-morpholinosydnonimine (SIN-1) through spontaneous liberation of nitric oxide (NO) and superoxide (O(2)(.-)). The aim of this study was to compare the effects of MO and its active metabolite SIN-1 on the redox status of rat erythrocytes and reticulocytes. Rat erythrocyte as well as reticulocyte-rich red blood cell (RBC) suspensions were aerobically incubated (2 h, 37 degrees C) without (control) or in the presence of different concentrations of MO or SIN-1. In rat erythrocytes, biotransformation of MO resulted in the production of NO and nitroxyl (NO(-)). Endogenous superoxide anion (O(2)(.-)) participated in peroxynitrite generation. SIN-1 simultaneously liberated NO and O(2)(.-), which formed peroxynitrite (at least in part), but the liberated NO predominantly reacted with haemoglobin, forming methaemoglobin in erythrocytes. In reticulocytes, MO and SIN-1 caused an increase in the levels of both nitrite and 3-nitrotyrosine (an indicator of peroxynitrite), whereas they decreased the level of O(2)(.-). In reticulocytes, MO was metabolized into SIN-1 which led to the generation of NO, which reacted with O(2)(.-) (endogenous or exogenous) forming reactive nitrogen species. In conclusion, there are two metabolic pathways for MO biotransformation: one causing NO and NO(-) generation predominantly in erythrocytes and the other, via SIN-1 metabolism, in reticulocytes. The main difference between the action of MO and SIN-1 was that the latter caused oxidative damage in RBCs.

The effects of nitric oxide synthesis on the Na+ ,K(+)-ATPase activity in guinea pig kidney exposed to lipopolysaccharides

Endotoxins (lipopolysaccharides; LPS) are known to cause multiple organ failure, including renal dysfunction. LPS triggers the synthesis and release of cytokines and the vasodilator nitric oxide (NO*). A major contributor to the increase in NO* production is LPS-stimulated expression of inducible nitric oxide synthase (iNOS). This occurs in vasculature and most organs including the kidney. During endotoxemia, NO* and superoxide react spontaneously to form the potent and versatile oxidant peroxynitrite (ONOO-) and the formation of 3-nitrotyrosine (nTyr)-protein adducts is a reliable biomarker of ONOO- generation. Therefore, the present study was aimed at investigating the role of endogenous nitric oxide in regulating Na+,K(+)-ATPase activity in the kidney, and at investigating the possible contribution of reactive nitrogen species (RNS) by measuring of iNOS activity. In addition, the present study was aimed at investigating the relationship between nTyr formation with iNOS and Na+,K(+)-ATPase activities. Previously in our study, nTyr was not detectable in kidney of normal control animals but was detected markedly in LPS exposed animals. In this study, kidney Na+,K(+)-ATPase activity were maximally inhibited 6 h after LPS injection (P:0.000) and LPS treatment significantly increased iNOS activity of kidney (P:0.000). The regression analysis revealed a very close correlation between Na+,K(+)-ATPase activity and nTyr levels of LPS treated animals (r = -0.868, P = 0.001). Na+,K(+)-ATPase activity were also negatively correlated with iNOS activity (r = -0.877, P = 0.001) in inflamed kidney. These data suggest that NO* and ONOO- contribute to the development of oxidant injury. Furthermore, the source of NO* may be iNOS. iNOS are expressed by the kidney, and their activity may increase following LPS administration. In addition, NO* and ONOO- formation inhibited Na+,K(+)-ATPase activity. This results also have strongly suggested that bacterial LPS disturbs activity of membrane Na+,K(+)-ATPase that may be an important component leading to the pathological consequences such as renal dysfunction in which the production of RNS are increased as in the case of LPS challenge.