Cytotoxicity and DNA damage in the neutrophils of patients with sickle cell anaemia treated with hydroxyurea

Iron Chelation Reduces DNA Damage in Sickle Cell Anemia

Sickle cell anemia (SCA) is a blood condition that causes severe pain. One of the therapeutic agents used for the treatment of SCA is hydroxyurea, which reduces the episodes of pain but causes DNA damage to white blood cells. The aim of this study was to evaluate the efficacy of the combination of hydroxyurea and iron chelation therapy in relation to the extent of DNA-associated damage. Blood samples were collected from 120 subjects from five groups. Various hematological parameters of the obtained serum were analyzed. The amount of damage caused to their DNA was detected using the comet assay and fluorescent microscopy techniques. The percentage of DNA damage in the group that was subjected to the combination therapy (target group) was 1.32% ± 1.51%, which was significantly lower (P < .05) than that observed in the group treated with hydroxyurea alone (6.36% ± 2.36%). While the target group showed comparable levels of hemoglobin F and lactate dehydrogenase compared to the group that was treated with hydroxyurea alone, highly significant levels of transferrin receptors and ferritin were observed in the target group. The results of this study revealed that the administration of iron chelation drugs with hydroxyurea may help improve patients' health and prevent the DNA damage caused to white blood cells due to hydroxyurea. Further studies are needed to better understand the underlying mechanisms that are involved in this process.

Effects of hydroxyurea on cytotoxicity, inflammation and oxidative stress markers in neutrophils of patients with sickle cell anemia: dose-effect relationship

Introduction

Although the efficacy of hydroxyurea (HU) in inhibiting erythrocyte sickling has been well demonstrated, the action of this drug on human neutrophils and the mechanism by which it improves the manifestations of the disease have not been studied thoroughly. We aimed to investigate the cell viability, along with inflammatory and oxidative markers in the neutrophils of sickle cell anemia (SCA) patients and the effects of HU therapy on these cells, by evaluating the dose-responsiveness.

Methods

In the present study, 101 patients (45 men and 56 women, aged 18–69 years) with SCA were divided into groups according to the use or not of HU: the SS group (without HU treatment, n = 47) and the SSHU group (under HU treatment, n = 54). The SSHU group was further stratified into subgroups according to the daily dose of the drug that patients already used: SSHU - 0.5 g (n = 19); SSHU - 1 g (n = 26) and SSHU - 1.5–2 g (n = 9). A control group (AA) comprised 50 healthy individuals. Neutrophils isolated from whole blood were analyzed using Trypan Blue, monoiodotyrosine (MTT) and lactate dehydrogenase (LDH) toxicity assays. Myeloperoxidase (MPO), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities and concentrations of interleukin 10 (IL-10), tumor necrosis factor alpha (TNF-α) and malonaldehyde (MDA) were also measured.

Results

Neutrophils from SCA patients showed membrane fragility and a significant decrease in cell viability when analyzed by Trypan Blue (p < 0.05), MTT (p < 0.001) and LDH (p = 0.011), compared to the AA group. Levels of inflammatory (MPO, TNF-α, and IL-10) and oxidative markers (SOD, GSH-Px, and MDA) were also altered (p < 0.05) in these cells, showing a significant difference in the SSHU-1g and SSHU - 1.5–2 g groups, compared to the SS group. Treatment with HU reverted the levels of all markers to concentrations similar to those in healthy individuals in a positive dose-effect relationship.

Conclusion

The HU did not generate a cytotoxic effect on neutrophils in SCA patients, but it modulated their oxidative and inflammatory mechanisms, promoting cytoprotection with a positive dose-effect.

Effects of oxidative stress on liver, brain and spinal cord of rats using L-NAME and treated with hydroxyurea. A model of sickle cell complication

PURPOSE

To analyze the serum levels of nitric oxide and correlate them with the levels of thiobarbituric acid reactive substances (TBARS) in liver, brain and spinal cord of animals using L-NAME and treated with hydroxyurea.

METHODS

Eighteen male albino Wistar rats were divided into three groups. NG-nitro-L-arginine methyl ester (L-NAME) was intraperitoneally administered to induce oxidative stress. TBARS and plasma nitric oxide levels were analyzed in all groups. Histopathology of the liver and vascular tissue was performed.

RESULTS

Statistically significant differences were seen in liver, brain and spinal cord TBARS levels.

CONCLUSIONS

Following the use of L-NAME, hepatic tissue increased the number of Kupffer cells as oxidative stress and inflammatory response increased. The use of L-NAME caused an increase in lipid peroxidation products and, consequently, in oxidative stress in animals. Hydroxyurea doses of 35 mg / kg / day reduced TBARS values in liver, brain and spinal cord.

Is chronic use of hydroxyurea safe for patients with sickle cell anemia? An account of genotoxicity and mutagenicity

Sickle cell anemia (SCA) is a hereditary hematological disease that is characterized by a point mutation in the beta globin S gene and has no specific treatment; hydroxyurea (HU) is the only therapeutic agent used in clinical practice. In the present study, we evaluated the deoxyribonucleic acid (DNA) damage index (DI) and chromosomal damage in leukocytes of adult patients with SCA with and without HU. The DI was assessed by the comet assay and chromosomal damage by the leukocyte micronucleus test of adult patients treated with HU (SCA-HU) and without the use of HU (SCA-NoHU). This is a cross-sectional study with 77 patients with SCA who attended a referral hospital in Fortaleza, Brazil. The control group (CG) consisted of 58 reportedly healthy individuals. The comparisons of means were performed by analysis of variance and Tukey's post-test. Values of P < 0.05 were considered statistically significant. SCA-NoHU patients had statistically higher DI values and a statistically significantly higher frequency of micronuclei compared to the CG. In addition, HU treatment accentuated DNA lesions by significantly increasing both parameters in treated patients (SCA-HU). HU potentiates DNA damage and the occurrence of chromosomal damage, which may promote genomic instability, mutation occurrence, and carcinogenesis. Studies are needed to evaluate the involved pathways, repair mechanisms, and the clinical impact that such damage can cause. Environ. Mol. Mutagen. 60:302-304, 2019. © 2018 Wiley Periodicals, Inc.