Reactive Oxygen Species In Red Blood Cells Research Articles

Nicotinamide Improves Anemia and Decreases Reactive Oxygen Species in Sickle Cell Disease Mice

The polymerization of deoxygenated HbS molecules in the red blood cells (RBCs) of patients with sickle cell disease (SCD) causes RBC destruction resulting in chronic pain, debilitating acute pain crises, strokes, multi-organ damage and a reduced life span. Therapeutic options remain limited. Bone marrow transplantation can be curative but is not an option for the majority of patients. Gene therapy interventions that also offer the promise of a cure are under investigation but are not likely to be available to the vast majority of patients in the near future. Hydroxyurea, the first drug approved for treatment of SCD, increases levels of Fetal Hemoglobin (HbF) that inhibit polymerization of HbS molecules but is not effective in all patients while a more powerful HbF-inducing drug, the DNA methyltransferase inhibitor decitabine has yet to be approved. L-glutamine, another approved therapeutic option, increases NAD redox potential and decreases reactive oxygen species (ROS) in the sickle RBCs to reduce symptoms. In our laboratory we have observed that increased ROS is associated with the retention of mitochondria in the SCD RBCs and have hypothesized that the abnormal presence of mitochondria in these cells is a major source of ROS (Jagadeeswaran et al Exp Hematol 50:46-52, 2017). In this investigation we have tested the hypothesis that chronic oral supplementation with nicotinamide, a direct precursor of NAD synthesis, would improve NAD redox potential, decrease mitochondrial retention and ROS in SCD RBCs, and reduce anemia in the SCD mouse model. The effect of nicotinamide was tested in SCD mice whose drinking water was supplemented for three months with 1% nicotinamide. The percentage of RBCs retaining mitochondria and the levels of ROS were determined by flow cytometric assays using the mitochondrial-specific dye TMRM and the ROS probe CM-H2DCFDA, respectively. In SCD mice receiving nicotinamide the fraction of RBCs retaining mitochondria was reduced 22.1% (p<0.05) and the level of ROS in RBCs was reduced 41% (p<0.01) compared to control SCD mice. The reticulocyte percentage was reduced 28% in nicotinamide-treated SCD mice compared to control SCD mice (p<0.01). The total RBC count was 30% higher (p<0.05) in nicotinamide-treated mice (6.61±0.76 X 10 6/μl) compared to control SCD mice (5.08±0.70 X 10 6/μl). Similar differences in hematocrit and total hemoglobin were also observed but failed to reach statistical significance. Total NAD levels were not significantly different in SCD mice receiving nicotinamide compared to control SCD mice (p<0.05), but the NADH/NAD total ratio was increased 2 fold (p<0.05). These results show that oral administration of high doses of nicotinamide decreases mitochondrial retention and ROS in SCD RBCs and improves NAD redox potential and anemia in SCD mice. These effects strongly suggest that additional studies be performed to investigate nicotinamide as a therapeutic option in SCD. [Display omitted] DisclosuresSaunthararajah: EpiDestiny: Consultancy, Current holder of individual stocks in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties.

The Role of RBC Oxidative Stress in Sickle Cell Disease: From the Molecular Basis to Pathologic Implications.

Sickle cell disease (SCD) is an inherited monogenic disorder and the most common severe hemoglobinopathy in the world. SCD is characterized by a point mutation in the β-globin gene, which results in hemoglobin (Hb) S production, leading to a variety of mechanistic and phenotypic changes within the sickle red blood cell (RBC). In SCD, the sickle RBCs are the root cause of the disease and they are a primary source of oxidative stress since sickle RBC redox state is compromised due to an imbalance between prooxidants and antioxidants. This imbalance in redox state is a result of a continuous production of reactive oxygen species (ROS) within the sickle RBC caused by the constant endogenous Hb autoxidation and NADPH oxidase activation, as well as by a deficiency in the antioxidant defense system. Accumulation of non-neutralized ROS within the sickle RBCs affects RBC membrane structure and function, leading to membrane integrity deficiency, low deformability, phosphatidylserine exposure, and release of micro-vesicles. These oxidative stress-associated RBC phenotypic modifications consequently evoke a myriad of physiological changes involved in multi-system manifestations. Thus, RBC oxidative stress in SCD can ultimately instigate major processes involved in organ damage. The critical role of the sickle RBC ROS production and its regulation in SCD pathophysiology are discussed here.

Cerium oxide nanoparticles protect red blood cells from hyperthermia-induced damages.

Heat stroke and severe fever cause anemia, although the underlying mechanism remains unclear. Here, we report the use of Cerium oxide nanoparticles in protection of red blood cells against damage caused by exposure to short-term hyperthermia (42°C, 10 min). Red blood cells exposed to hyperthermia exhibited extradition senescence with higher density, smaller size and lower zeta potential relative to those under normal physiological environment (37°C, 10 min). Furthermore, hyperthermia-exposed cells exhibited significantly higher reactive oxygen species (ROS) production compared to the normal conditions. Importantly, the preconditional treatment, using Ceria nanoparticles (CNPs), ameliorated senescence and apoptosis in red blood cells damaged by hyperthermia by reducing ROS levels. Summarily, short-term hyperthermia caused a significant increase in ROS in red blood cells, and resulted in senescence and apoptosis. These may be possible mechanisms of pathological changes in red blood cells exposed to heat stroke or severe fever. Overall, these findings indicate that CNPs strongly inhibit ROS production, and effectively ameliorates hyperthermia-induced damages in red blood cells.

Oxidative Stress and Thrombosis during Aging: The Roles of Oxidative Stress in RBCs in Venous Thrombosis.

Mid-life stage adults are at higher risk of developing venous thrombosis (VT)/thromboembolism (VT/E). Aging is characterized by an overproduction of reactive oxygen species (ROS), which could evoke a series of physiological changes involved in thrombosis. Here, we focus on the critical role of ROS within the red blood cell (RBC) in initiating venous thrombosis during aging. Growing evidence has shifted our interest in the role of unjustifiably unvalued RBCs in blood coagulation. RBCs can be a major source of oxidative stress during aging, since RBC redox homeostasis is generally compromised due to the discrepancy between prooxidants and antioxidants. As a result, ROS accumulate within the RBC due to the constant endogenous hemoglobin (Hb) autoxidation and NADPH oxidase activation, and the uptake of extracellular ROS released by other cells in the circulation. The elevated RBC ROS level affects the RBC membrane structure and function, causing loss of membrane integrity, and decreased deformability. These changes impair RBC function in hemostasis and thrombosis, favoring a hypercoagulable state through enhanced RBC aggregation, RBC binding to endothelial cells affecting nitric oxide availability, RBC-induced platelet activation consequently modulating their activity, RBC interaction with and activation of coagulation factors, increased RBC phosphatidylserine exposure and release of microvesicles, accelerated aging and hemolysis. Thus, RBC oxidative stress during aging typifies an ultimate mechanism in system failure, which can affect major processes involved in the development of venous thrombosis in a variety of ways. The reevaluated concept of the critical role of RBC ROS in the activation of thrombotic events during aging will help identify potential targets for novel strategies to prevent/reduce the risk for VT/E or VT/E recurrences in mid-life stage adults.

Impact of a 10km running trial on eryptosis, red blood cell rheology, and electrophysiology in endurance trained athletes: a pilot study.

Blood rheology is a key determinant of blood flow and tissue perfusion. There are still large discrepancies regarding the effects of an acute running exercise on blood rheological properties and red blood cell (RBC) physiology. We investigated the effect of a 10km running trial on markers of blood rheology and RBC physiology in endurance trained athletes. Blood was sampled before and after the exercise to measure lactate and glucose, hematological and hemorheological parameters (blood viscosity, RBC deformability, and aggregation), eryptosis markers (phosphatidylserine and CD47 exposure, RBC reactive oxygen species), RBC-derived microparticles (RBC-MPs), and RBC electrophysiological activity. Weight was measured before and after exercise. Peripheral oxygen saturation and heart rate were monitored before and during the trial. Blood lactate and glucose levels increased after exercise and subjects significantly lost weight. All athletes experienced a significant fall in oxygen saturation. Mean corpuscular volume (MCV) was increased from 95.1 ± 3.2 to 96.0 ± 3.3 and mean corpuscular hemoglobin concentration (MCHC) decreased after exercise suggesting a slight RBC rehydration. Exercise increased RBC deformability from 0.344 ± 0.04 to 0.378 ± 0.07, decreased RBC aggregates strength and blood viscosity, while hematocrit (Hct) remained unaffected. While RBC electrophysiological recording suggested a modulation in RBC calcium content and/or chloride conductance, eryptosis markers and RBC-MPs were not modified by the exercise. A 10km acute running exercise had no effect on RBC senescence and membrane blebbing. In contrast, this exercise increased RBC deformability, probably through rehydration process which resulted in a decrease in blood viscosity.

Mn Porphyrin-Based Redox Active Drugs Improve Anemia and Reduce Organ Damage in a Murine Model of Sickle Cell Disease

Sickle cell disease (SCD) is caused by a point mutation in the β-globin gene that leads to devastating downstream consequences including chronic hemolytic anemia, episodic vascular occlusion, and cumulative oxidative organ damage resulting in death. Targeting the mechanisms leading to organ injury could bring out therapeutic approaches. Sickle red blood cell (RBC) oxidative damage, which leads to hemolysis, could participate in endothelial activation and organ damage. Recently, we show that NADPH oxidases (NOXs) are a major player in generating reactive oxygen species (ROS) within sickle RBCs to mediate adhesion and vaso-occlusion. We have now evaluated the effects of reducing ROS in sickle RBCs on hemolysis, and its consequences on endothelial activation and organ damage in sickle mice in vivo. To inactive RBC NOXs, thus reduce ROS levels, we used the redox-active manganese (Mn) porphyrins, MnTnBuOE-2-PyP5+ (MnBuOE) and MnTE-2-PyP5+ (MnE), commonly known as superoxide dismutase (SOD) mimics. Treatments of sickle mice for 4 weeks with 0.1 mg/kg MnBuOE and 1 mg/kg MnE significantly reduced sickle RBC ROS production profile compared to sickle RBC ROS levels in the control vehicle group (p&lt;0.05), suggesting that Mn porphyrins protects sickle RBCs especially against NOX activation. Mn porphyrins also significantly affected apoptosis-like RBC death called eryptosis characterized by accelerated membrane senescence and PS externalization. Sickle mice-treated with vehicle showed 4.98±0.6% annexin V-positive sickle RBCs. However, 0.1 mg/kg MnBuOE and 1 mg/kg MnE markedly decreased the percentage of annexin V-binding sickle RBCs by 54% (p=0.0009) and 56% (p=0.0007), respectively. As a result of improved eryptosis, RBC counts rose from 5.23 x 106/mL in vehicle-treated sickle mice to 5.99 x 106/mL in MnE-treated mice. Hemoglobin (Hb) levels also rose from 7 g/dL in the vehicle group to 8.55 g/dL in MnE-treated mice. Accordingly, hematocrits rose from 26.1% in vehicle-treated mice to 28.59% in MnE-treated mice. Yet, reticulocyte counts were not significantly different between vehicle and MnE-treated sickle mice, implying less hemolysis and not an increase in RBC production. The effect of reduced hemolysis by Mn porphyrins on oxidative stress in different organs was next assessed. MnBuOE and MnE decreased ROS levels in the kidneys (p&lt;0.03 for MnBuOE and MnE), liver (p&lt;0.05 for MnBuOE and MnE), and spleen (p&lt;0.004 for MnBuOE and MnE) compared to the vehicle-treated group. Since organ ROS levels were lowered, this outcome may be accompanied by down-regulation of activation of endothelial adhesion molecules VCAM-1, ICAM-1, and P-selectin, markers of endothelial dysfunction and disease severity and/or RBC and leukocyte adhesion in SCD. Indeed, adhesion molecule expression assays by qRT-PCR showed that MnBuOE suppressed ICAM-1 and VCAM-1 expression in the lungs (p&lt;0.0001 and p=0.0054, respectively) and kidneys (p=0.0072 and p=0.0004, respectively), and P-selectin expression (p=0.0058) in the kidneys. MnE also down-regulated the expression of ICAM-1 in the lungs (p&lt;0.0001) and kidneys (p=0.0125), and VCAM-1 (p=0.0038) in the kidneys. These drugs had no effect on ICAM-1, VCAM-1, and P-selectin expression in the liver and spleen. Based on these data, we assumed that Mn porphyrins might rescue damage of organs typically affected and impaired in SCD. Apoptosis and necrosis of the kidneys, liver, and spleen were assessed using annexin V apoptosis detection kit and H&amp;E staining. Sickle mice treated with vehicle showed marked apoptosis in the kidney, liver, and spleen (p=0.0314) tissues, and necrosis. However, 0.1 mg/kg MnBuOE and 1 mg/kg MnE significantly decreased apoptosis (p&lt;0.0001) and necrosis in the kidneys, and liver (p=0.0355). MnBuOE also reduced apoptosis (p=0.0314) and necrosis in the spleen. These data suggest that Mn porphyrins can alleviate organ impairment and damage via at least RBC and endothelial oxidative stress reduction. As a result of these beneficial outcomes of reduced hemolysis, endothelial oxidative damage and dysfunction, Kaplan-Meier survival curves showed a dramatic prolonged survival of sickle mice challenged with TNFα (p = .0009, log-rank test). Our data suggest that Mn porphyrins, by repressing NOX-mediated hemolysis could represent a novel therapeutic intervention to especially alleviate hemolysis-mediated endothelial activation and organ damage in SCD. Disclosures No relevant conflicts of interest to declare.

Mn Porphyrin-Based Redox Active Drugs As Novel Anti-Adhesive and Anti-Inflammatory Agents Targeting Sickle Red Blood Cell Oxidative Damage In Vivo

In sickle cell disease (SCD), painful vaso-occlusive crises and end-organ damage are caused by occlusion of the vessels due largely to sickle red blood cell (RBC) adhesion to both the endothelium and adherent leukocytes. RBC oxidative damage caused by continuous endogenous and exogenous oxidative stress may participate in the occurrence of vaso-occlusive crises.We have evaluated the effects of scavenging reactive oxygen species (ROS) in sickle RBCs on cell adhesion and vaso-occlusion in a humanized mouse model of vaso-occlusion in vivo analyzed by intravital microscopy. To scavenge RBC ROS, we used our manganese porphyrin-based superoxide dismutase (SOD) mimics MnTnBuOE-2-PyP5+ (MnBuOE) and MnTE-2-PyP5+ (MnE), powerful catalysts of superoxide dismutation, and reductants of peroxynitrite, peroxide and hypochlorite. Intravital microscopy observations of enflamed vessels visible through dorsal skin-fold window chamber implants was performed after the inflammatory trigger of tumor necrosis factor alpha (TNFα) to induce vaso-occlusion in transgenic sickle mice followed by subcutaneous injection of MnBuOE at 0.1, 0.2 or 2 mg/kg, or MnE at 0.5 or 2 mg/kg.Treatment of sickle mice with only one dose of 0.1, 0.2 and 2 mg/kg MnBuOE decreased dose-dependently adhesion of both sickle cells and leukocytes in enflamed vessels by 68±4% (p<0.01), 85±2.3% (p<0.01) and 89±4.3% (p<0.01), respectively, compared with vehicle-treated sickle mice. MnBuOE at 0.1, 0.2 and 2 mg/kg also caused significant and dose-dependent reduction in leukocyte rolling flux (p<0.05). Similar inhibitory benefits were obtained when MnE was administered to TNFa-treated sickle mice. MnE at 0.5 and 2 mg/kg significantly decreased the number of adherent sickle cells and leukocytes by 76±8.6% (p<0.01) and 92±2.5% (p<0.01), respectively, and leukocyte rolling flux (p<0.01) compared to vehicle-treated animals. The effect of these two SOD mimics on sickle RBCs and leukocyte adhesion, and leukocyte rolling flux was rapid, because a decline in cell adhesion and leukocyte rolling flux were already detectable within the first 15 minutes after injection of the compounds. In contrast, cell adhesion and leukocyte rolling flux were already pronounced 15 minutes following vehicle injection. Reduced cell adhesion to the endothelium by the SOD mimics resulted in improved microcirculatory blood flow in sickle mice. These favorable effects on cell adhesion and vaso-occlusion following SOD mimic treatment were indeed due at least to the significant decrease in sickle RBC ROS levels compared to vehicle-treated mice (p<0.001).The long-term anti-adhesive and anti-inflammatory effects of MnBuOE and MnE in sickle mice were next examined. Subcutaneous administration for 28 days of MnBuOE at 0.1 and 0.5 mg/kg inhibited significantly adhesion of RBCs and leukocytes in enflamed venules by 34±13% (p<0.05) and 69±3.5% (p<0.001), respectively, and leukocyte rolling flux (p<0.001) compared to vehicle-treated sickle mice. Subcutaneous injection of MnE at 0.5 and 1 mg/kg for 28 days also had significant effect on sickle cell and leukocyte adhesion (p<0.01), and leukocyte rolling flux (p<0.01). In addition, venous blood gases were significantly improved by the SOD mimics. The levels of partial pressure of Carbon dioxide (pCO2), partial pressure of oxygen (pO2), base excess of the extracellular fluid (BEecf), bicarbonate (HCO3-) concentration, total CO2 (TCO2) concentration, and the indicators of hypoxia, hemoglobin saturation of oxygen (sO2) and lactate, became close to or within the normal ranges (p<0.05) in sickle mice treated with 1 mg/kg MnE. MnBuOE at 0.1 mg/kg showed only a trend toward an increase in venous blood gases, with a significant decrease in lactate (p<0.05). Leukocytosis in sickle mice treated with the SOD mimics was also alleviated. A significant drop in leukocyte (p<0.05), neutrophil (p<0.01), lymphocyte (p<0.05) and monocyte (p<0.05) counts was detected in sickle mice treated with either 0.1 mg/kg MnBuOE or 1 mg/kg MnE. These beneficial therapeutic outcomes induced by the SOD mimics were due at least in part to a decline in RBC ROS levels (p<0.001) and RBC phosphatidylserine surface exposure (p<0.05), an eryptosis marker.These results suggest that our SOD mimics may represent a valuable novel therapeutic intervention for not only vaso-occlusive crises, but inflammation as well, that should be further evaluated in patients with SCD. DisclosuresNo relevant conflicts of interest to declare.

Hydroxyurea therapy modulates sickle cell anemia red blood cell physiology: Impact on RBC deformability, oxidative stress, nitrite levels and nitric oxide synthase signalling pathway

Hydroxyurea (HU) has been suggested to act as a nitric oxide (NO) donor in sickle cell anemia (SCA). However, little is known about the HU NO-related effects on red blood cell (RBC) physiology and NO signalling pathway.Thirty-four patients with SCA (22 under HU treatment (HU+) and 12 without (HU-)) and 17 healthy subjects (AA) were included. RBC nitrite content, deformability and reactive oxygen species (ROS) levels were measured. RBC NO-synthase (RBC-NOS) signalling pathway was assessed by the measurement of RBC-NOS serine1177 and RBC-AKT serine473 phosphorylation. We also investigated the in vitro effects of Sodium Nitroprusside (SNP), a NO donor, on the same parameters in SCA RBC.RBC nitrite content was higher in HU+ than in HU- and AA. RBC deformability was decreased in SCA patients compared to AA but the decrease was more pronounced in HU-. RBC ROS level was increased in SCA compared to AA but the level was higher in HU- than in HU+. RBC-NOS serine1177 and RBC-AKT serine473 phosphorylation were decreased in HU+ compared to HU- and AA. SCA RBC treated with SNP showed increased deformability, reduced ROS content and a decrease in AKT and RBC-NOS phosphorylation.Our study suggests that HU, through its effects on foetal hemoglobin and possibly on NO delivery, would modulate RBC NO signalling pathway, RBC rheology and oxidative stress.

Sickle Cell Disease Is Associated with Reduced Adenosine Deaminase Catalytic Activity, Resulting in Altered Adenosine Metabolism

Abstract 1078Sickle cell disease (SCD), a chronic hemolytic anemia due to a mutant beta-globin, is associated with prominent inflammatory features with elevated levels of inflammation mediating molecules and an oxidative state, with elevated levels of reactive oxygen species (ROS). Additionally, elevated levels of adenosine (Ado) have recently been shown to play a role in exacerbating sickle cell pathophysiology. However, the etiology of increased Ado is unclear; and presumed to occur secondary to increased ATP release from cellular damage (Xu et al, Nature Medicine, 2010). Herein, we show that increased levels of Ado in the plasma of patients with SCD and the mouse model of SCD [Berkeley sickle (SS) mice] were accompanied by significantly reduced catalytic activity of the Ado degrading enzyme, adenosine deaminase (ADA) in sickle red blood cell (RBCs). ADA activity in Berkeley sickle (SS) RBCs was 246 ± 50 U/L as compared to 570 ± 36 U/L in normal mouse RBCs (derived from Berkeley AA/WT mice), as measured by a color-based enzymatic assay. Notably, despite lower enzyme activity of ADA, immunoblotting assays showed that the levels of ADA protein in sickle RBC were similar, or even slightly higher compared to that in wild type (WT) RBC, suggesting that ADA catalytic activity was impaired in sickle RBCs. In vitro plasma swap experiments, where WT RBC are incubated with sickle plasma and vice versa for an hour, revealed that sickle plasma induced a significant decrease in ADA activity in WT RBC, suggesting that plasma from sickle mice contains a soluble factor that is capable of impairing ADA enzyme activity. Interestingly enough, the decrease in ADA activity correlated inversely with the levels of intracellular RBC ROS in sickle mice. Next we directly assess in vivo the effect of induced oxidative stress on RBC ADA activity in sickle mice by injecting sickle mice with 35umoles/Kg body weight of hemin and saline respectively. Preliminary data suggests a decrease in RBC ADA activity in hemin–injected mice (294 ± 197 U/L) compared to the saline-injected group (346 ± 185.8 U/L), and this data was consistent with a concomitant increase in intracellular RBC and white blood cells ROS levels. We conclude that increase in oxidative stress levels mediates a post translational alteration of ADA catalytic activity and alters Ado metabolism in SCD. Disclosures:No relevant conflicts of interest to declare.

Medicaments: Gifts from the jungle

Medicaments: Gifts from the jungle

Implication of oxidative stress as a cause of autoimmune hemolytic anemia in NZB mice

We have recently shown that deficiency of the superoxide dismutase 1 gene (SOD1) causes anemia and autoimmune responses against red blood cells (RBCs) and that transgenic expression of human SOD1 in erythroid cells rescues them. Because these phenotypes observed in SOD1-deficient mice are similar to autoimmune hemolytic anemia (AIHA), a causal connection between reactive oxygen species (ROS) and AIHA was examined using an AIHA-prone New Zealand Black (NZB) mouse. ROS levels in RBCs were high in young NZB mice, compared to control New Zealand White (NZW) mice, and increased during aging. Methemoglobin and lipid peroxidation products were elevated during aging, consistent with the elevated oxidative stress in RBCs of NZB mice. Severity of anemia and levels of intracellular ROS were positively correlated. Levels of antibodies against 4-hydroxynonenal and acrolein were also elevated in NZB mice. Transgenic expression of human SOD1 protein in RBCs of NZB mice suppressed ROS in RBCs and decreased the death rate. When RBCs from C57BL/6 mice were injected weekly into the same strain of mice, production of anti-RBC antibody was observed only in mice that had been injected with oxidized RBCs. Thus, oxidation-mediated autoantibody production may be a more general mechanism for AIHA and related autoimmune diseases.

Vitamin E Supplementation Reduces Oxidative Stress in Beta Thalassaemia Intermedia

Objective: The aim of this investigation was to study the effect of vitamin E treatment in oxidative stress of red and white cells of β-thalassaemia intermedia patients. Methods: Nine patients undergoing occasional transfusions (5 females/4 males), median age 39 years (range 15–74), were recruited for oral daily administration of 400 IU vitamin E for 3 months. Twenty-seven milliliters of peripheral blood was obtained before and after 3 months of treatment, and 3 months after treatment completion. In the case of transfused patients (n = 4), blood was obtained at least 30 days after transfusion. Reactive oxygen species (ROS) was measured by flow cytometry; red blood cell (RBC) reduced glutathione (GSH) was measured by dinitrothiocyanobenzene reduction, serum malondialdehyde was measured in terms of thiobarbituric acid-reactive substances (TBARS), and α-haemoglobin-stabilizing protein (AHSP) mRNA expression was measured by real-time polymerase chain reaction of reticulocyte RNA extracts. Results: β-Thalassaemia patients presented basal levels of RBC ROS, GSH and serum TBARS statistically different compared with healthy controls. However, after vitamin E administration, patients presented a significant reduction in erythrocyte RBC ROS and serum TBARS levels. In parallel, red cell GSH was significantly increased after treatment. Peripheral mononuclear cells and T lymphocytes also demonstrated a reduction in ROS production. Therefore, after treatment, no significant differences were detected comparing patients and normal controls. Three months after treatment completion, all measurements showed a tendency of returning to basal values. A significant reduction in reticulocyte number was observed after vitamin E treatment. Vitamin E treatment did not modify levels of haemoglobin or AHSP mRNA expression. Conclusion: Although vitamin E is not capable of reducing anaemia in these patients, it could be useful for reducing oxidative damage in other target organs of β-thalassaemic patients. Finally, this is the first study to analyse the effects of vitamin E on ROS production in red and white blood cells and AHSP mRNA expression.

Arsenic induced blood and brain oxidative stress and its response to some thiol chelators in rats

Chronic arsenic toxicity is a widespread problem, not only in India and Bangladesh but also in various other regions of the world. Exposure to arsenic may occur from natural or industrial sources. The treatment that is in use at present employs administration of thiol chelators, such as meso 2,3-dimercaptosuccinic acid (DMSA) and sodium 2,3-dimercaptopropane 1-sulfonate (DMPS), which facilitate its excretion from the body. However, these chelating agents are compromised with number of limitations due to their lipophobic nature, particularly for their use in cases of chronic poisoning. During chronic exposure, arsenic gains access into the cell and it becomes mandatory for a drug to cross cell membrane to chelate intracellular arsenic. To address this problem, analogs of DMSA having lipophilic character, were examined against chronic arsenic poisoning in experimental animals. In the present study, therapeutic efficacy of meso 2,3-dimercaptosuccinic acid (DMSA), sodium 2,3-dimercaptopropane 1-sulfonate (DMPS), monoisoamyl DMSA (MiADMSA) were compared in terms of reducing arsenic burden, as well as recovery in the altered biochemical variables particularly suggestive of oxidative stress. Adult male Wistar rats were given 100-ppm arsenic for 10 weeks followed by chelation therapy with the above chelating agents at a dose of 50 mg/Kg (orally) once daily for 5 consecutive days. Arsenic exposure resulted in marked elevation in reactive oxygen species (ROS) in blood, inhibition of ALAD activity and depletion of GSH. These changes were accompanied by significant decline in blood hemoglobin level. MiADMSA was the most effective chelator in reducing ROS in red blood cells, and in restoring blood ALAD compared to two other chelators. Brain superoxide dismutase (SOD) and glutathione peroxidase (GPx) decreased, while ROS and TBARS increased significantly following arsenic exposure. There was a significant increase in the activity of glutathione-S-transferase (GST) with a corresponding decline in its substrate i.e. glutathione. Among all the three chelators, MiADMSA showed maximum reduction in the level of ROS in brain. Additionally, administration of MiADMSA was most effective in counteracting arsenic induced inhibition in brain ALAD, SOD and GPx activity. Based on these results and in particular higher metal decorporation from blood and brain, we suggest MiADMSA to be a potential drug of choice for the treatment of chronic arsenic poisoning. However, further studies are required for the choice of appropriate dose, duration of treatment and possible effects on other major organs.