The influence of hydroxyurea on oxidative stress in sickle cell anemia

Abstract In sickle cell anemia (SCD) and thalassemia, although the basic lesions are mutations in the globin genes, the pathophysiology involves oxidative stress-mediated cell damage in the bone marrow (ineffective erythropoiesis due to apoptosis of early erythroid precursors) and in the peripheral blood (chronic hemolysis of mature RBC). In addition, some patients develop thromboembolic complications and recurrent bacterial infections, the etiology of which is related at least in part, to documented oxidative stress in platelets and neutrophils (PMN), respectively. To study the presence and the role of oxidative stress in thalassemia and SCD, we adapted flow cytometry techniques for measuring the generation of Reactive Oxygen Species (ROS), the content of reduced glutathione (GSH), membrane lipid peroxidation and externalization of phosphatidylserine (PS) moieties in RBC, platelets and PMN. Cells derived from the peripheral blood of patients with beta-thalassemia major, intermedia or SCD showed increased oxidative status (increased ROS, lipid peroxidation and PS externalization, and decreased GSH) compared with their normal counterparts. Incubating fresh blood samples from patients with thalassemia major and thalassemia intermedia with 10 mg/ml FPP for 16 hours at 37oC reduced the oxidative status of RBC as well as platelets and PMN. Experiments carried out in normal and thalassemic mice (Th3/+, a mouse model of human beta-thalassemia intermedia demonstrated that mice treated for one week with 10 mg/ml FPP (dissolved in the drinking water) had reduced oxidative stress compared to control mice. The in-vivo effect of FPP was tested on 9 patients with beta-thalassemia (6 - major and 3 - intermedia) treated with 3 gr FPP per os three times a day for 12–15 weeks. Following the treatment, the ROS in RBC, platelets and PMN decreased and the GSH increased in all patients (see table). Six of these patients responded by a modest increase in RBC, reticulocytes and hemoglobin levels. These results suggest that FPP may have an important clinical efficacy as an antioxidant in thalassemia and sickle cell anemia. The in vivo effect of FPP treatment of beta-thalassemia patients Baseline After treatment n Mean ± SE Mean ± SE P-value* * Paired samples t-test RBC 9 324.07 ± 29.19 209.55 ± 23.65 0.001 ROS Platelets 9 223.73 ± 26.49 109.11 ± 8.71 0.001 PMN 9 222.72 ± 46.42 117.61 ± 8.98 0.045 RBC 9 55.37 ± 5.37 94.88 ± 3.71 0.001 GSH Platelets 9 59.41 ± 4.98 97.55 ± 5.26 <0.0001 PMN 9 58.29 ± 5.35 90.06 ± 5.87 0.005

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Faculty Opinions recommendation of The influence of hydroxyurea on oxidative stress in sickle cell anemia.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.725819853.793510063 ◽

2015 ◽

Author(s):

Marilyn Telen

Keyword(s):

Oxidative Stress ◽

Sickle Cell ◽

Sickle Cell Anemia

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Impact of βS-Globin Haplotypes on Oxidative Stress in Patients with Sickle Cell Anemia in Steady State

Archives of Medical Research ◽

10.1016/j.arcmed.2012.08.014 ◽

2012 ◽

Vol 43 (7) ◽

pp. 536-540 ◽

Cited By ~ 3

Author(s):

Bruna Stefânia Carvalho-dos Santos ◽

Darcielle Bruna Dias-Elias ◽

Lilianne Brito da Silva-Rocha ◽

Maritza Cavalcante-Barbosa ◽

Romélia Pinheiro-Gonçalves

Keyword(s):

Oxidative Stress ◽

Steady State ◽

Sickle Cell ◽

Sickle Cell Anemia

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Antioxidant Vitamins C and E Supplementation Does Not Improve the Hemolytic Profile of Sickle Cell Anemia Patients: A Randomized, Double-Blind, Placebo-Controlled Trial

Blood ◽

10.1182/blood.v118.21.1063.1063 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1063-1063

Author(s):

Martha Mariana A S Arruda ◽

Grazielle Mecabo ◽

Celso Arrais Rodrigues ◽

Sandra S Matsuda ◽

Iara Baldim Rabelo ◽

...

Keyword(s):

Oxidative Stress ◽

Uric Acid ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Reticulocyte Count ◽

Antioxidant Vitamins ◽

Vitamin Supplementation ◽

Indirect Bilirubin ◽

Severe Deficiency ◽

The Impact

Abstract Abstract 1063 Background: Erythrocytes of sickle cell anemia (SCA) patients continuously produce larger amounts of pro-oxidants than normal cells, and oxidative stress seems to play a significant role in the pathophysiology of this disease. In erythrocytes, oxidative stress primarily affects the membrane and results in hemolysis. The use of antioxidants in vitro reduces the generation of pro-oxidants, which could prevent adhesion and phagocytosis of oxidized erythrocytes. Aims: To evaluate the impact of antioxidant vitamins C (vitC) and E (vitE) supplementation in the hemolytic profile in SCA patients. Patients and methods: Homozygous SCA or S-β-thalassemia patients, over 18 years, were randomly assigned to receive VitC 1,400 mg + VitE 800 mg per day or placebo, administered orally for 180 days. Pregnant women and patients with iron overload out of chelation therapy were excluded. Patients were evaluated clinically and blood samples were collected at days 0 and 180 for complete blood count, automated reticulocyte count, indirect bilirubin, lactate dehydrogenase (LDH), haptoglobin, uric acid, and serum levels of VitC and VitE. Results: Overall, 83 patients were enrolled (44 vitamins, 39 placebo). The median (range) age was 27 (18–68) years, and 53 (64%) were female. There were no significant differences between the two groups as regards clinical complications of SCA or baseline laboratorial tests and serum vitC and vitE. Sixty percent of the patients were VitC deficient (30% with severe deficiency), 70% were VitE deficient (33% with severe deficiency) and 44% were deficient in both vitamins. Vitamin supplementation increased VitC from 27.2 to 62.6 μMol/L (p<0.0001) and VitE from 13.9 to 20.2 μMol/L (p<0.0001). No changes in vitC or vitE were observed in patients receiving placebo. No significant changes in hemoglobin levels, hematocrit, mean corpuscular volume were observed in either group. However, patients receiving vitamin supplementation presented a significant increase in the median reticulocyte count (from 152 to 195 ×106/μL, p=0.01), LDH (from 396 to 425 U/L, p=0.018), indirect bilirubin (from 1.45 to 1.73 mg/dL, p<0.0001), and uric acid (from 4.75 to 5.15 mg/dL, p=0.02), and a decrease in the haptoglobin levels (from 3.95 to 3.45 mg/dL, p=0.06). Conclusion: Supplementation with vitamins C and E did not improve anemia and, surprisingly, increased markers of hemolysis in patients with SCA and S-β-thalassemia. The exact mechanisms to explain our findings and their clinical significance remain to be determined. Disclosures: No relevant conflicts of interest to declare.

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