High iron storage levels are associated with increased DNA oxidative injury in patients on regular hemodialysis

Impact on oxidative stress of oral, high-dose, iron supplementation for management of iron deficiency after bariatric surgery, a preliminary study

OBJECTIVES

High-dose oral iron supplementation for patients who develop iron deficiency after bariatric surgery may induce oxidative stress in the gastrointestine. The study's objective was to test this hypothesis by determining the impact of high-dose oral iron on systemic oxidative stress.

METHODS

We used archived plasma samples from a randomized controlled clinical trial (NCT02404012) comparing FeSO4 (195 mg/day, NatureMade®, West Hills, CA) with a heme iron polypeptide (HIP, 60.4 mg/day, Proferrin®, Colorado Biolabs, Lafayette, CO) for 8 weeks. Systemic oxidative stress was measured using malondialdehyde and total antioxidant capacity (MDA, Abcam, ab238537 and TAC, Abcam, ab65329 Cambridge, UK) assays. Data was log-transformed and presented as means and standard deviations; a mixed model was used to determine the effects of time (0, 2, 4, and 8 weeks) and treatment (FeSO4 versus HIP) on oxidative stress.

RESULTS

The FeSO4 (N = 8) and HIP (N = 5) participants were balanced in body mass index (35.0 ± 5.5 kg/m2), race (93 % White), time post-surgery (7.3 ± 3.3 years), as well as serum concentrations of iron (P > 0.05). The FeSO4 group tended to be older (44.3 ± 4.5 years) and they had lower concentrations of serum ferritin (6.5 ± 2.7 µg/mL) than the HIP (38.2 ± 9.3 years, and 12.9 ± 16.8 µg/mL) group (P = 0.080, and P = 0.017 respectively). We observed a larger increase in serum iron in the FeSO4 group during the 8 weeks of Fe supplementation, compared to that in the HIP group (p = 0.004). We observed a decreasing trend in MDA over the 8 weeks (p = 0.080) in the FeSO4 treatment group. There were no significant differences in TAC between and within FeSO4 and HIP groups over the 8 week supplementation period.

CONCLUSIONS

This preliminary study suggests that high-dose oral iron supplementation for iron deficiency does not adversely impact systemic oxidative stress in patients undergoing bariatric surgery.

The Effect of Iron Deficiency Anemia and Different Treatment Methods on DNA Damage: 8-hydroxy-2-deoxyguanosine Level

Ionic iron causes damages at the cellular level by forming free radicals. Reactive oxygen species lead to the formation of oxidative base damages in DNA. Among these forms the most common one and the one which has the best known mutagenity is 8-hydroxy-2′-deoxyguanosine (8-OHdG). We aimed to determine iron deficiency anemia (IDA) and its different forms of treatments; probable oxidative damage on DNA by looking at the level of 8-OHdG. The patients were divided into 4 subgroups: Oral treatment (p.o.) group; Intramuscular treatment (i.m.) group; Intravenous treatment (i.v.) group; Healthy control group. Blood and urine samples were taken from all patients totally 4 times. 8-OHdG levels detected in blood and urine samples were compared with the control group. IDA and the treatment of it affect the level of 8-OHdG. p.o. therapy should be the top priority on children.

Effect of a Ferric Citrate Formulation, a Phosphate Binder, on Oxidative Stress in Chronic Kidney Diseases-Mineral and Bone Disorder Patients Receiving Hemodialysis: A Pilot Study

A ferric citrate formulation for treating hyperphosphatemia is a new therapeutic that not only suppresses the accumulation of phosphorus in patients with chronic kidney disease-mineral bone disorders (CKD-MBD), but also ameliorates anemia caused by iron deficiency. In contrast, it has been demonstrated that intravenous iron injection markedly increases oxidative stress. This study was designed to investigate the effect of a ferric citrate formulation on oxidative stress in CKD-MBD patients receiving hemodialysis therapy. Fifteen CKD-MBD patients undergoing dialysis were enrolled in this study. The patients were orally administered a ferric citrate formulation for 6 months. Their plasma phosphorus concentrations remained unchanged with the switch from other phosphorus adsorbents to the ferric citrate formulation. In addition, the ferric citrate formulation generally allowed for dose reduction of an erythropoiesis stimulating agent with an increased hematopoietic effect. The average values of plasma ferritin level increased after the introduction of a ferric citrate formulation, but did not exceed 100 (ng/mL). Interestingly, oxidative stress markers did not increase significantly, and anti-oxidative capacity was not significantly decreased at 6 months after the drug administration. Similarly, no change was observed in any inflammation markers. The ferric citrate formulation induces negligible oxidative stress in CKD-MBD patients receiving dialysis under the present clinical condition.

Oxidative stress biomarkers and chromogranin A in uremic patients: effects of dialytic treatment

OBJECTIVE

To evaluate oxidative stress in uremia and dialysis and chromogranin A, a stress hormone that could be related to oxidative processes.

METHODS

Plasma oxidative stress biomarkers (-SH, 8-OHdG, and ox-LDL) and chromogranin A were measured in 89 outpatients (21 uremic patients, 17 in peritoneal dialysis, and 51 in haemodialysis), and in 18 subjects with normal renal function.

RESULTS

-SH groups were significantly reduced in heamodialysis, peritoneal, and uremic patients as compared with the control group (p=0.01), while 8-OHdG was increased (p<0.01). No differences were observed for ox-LDL. Chromogranin A was increased in uremic, peritoneal and haemodialysis patients (p<0.01), showing a positive correlation to 8-OHdG (p<0.01).

CONCLUSION

Oxidative stress biomarkers and chromogranin A levels differ between control subjects when compared to both uremic and dialysis patients. No differences were observed between uremic and dialysis patients, suggesting that uremia is the major source of the increase in oxidative stress and CgA levels in patients with end stage renal disease.

Impact of Magnetic Labeling on Human and Mouse Stem Cells and Their Long-Term Magnetic Resonance Tracking in a Rat Model of Parkinson Disease

Magnetic resonance imaging (MRI) of magnetically labeled stem cells has become a valuable tool in the understanding and evaluation of experimental stem cell–based therapies of degenerative central nervous system disorders. This comprehensive study assesses the impact of magnetic labeling of both human and rodent stem cell–containing populations on multiple biologic parameters as maintenance of stemness and oxidative stress levels. Cells were efficiently magnetically labeled with very small superparamagnetic iron oxide particles. Only under the condition of tailored labeling strategies can the impact of magnetic labeling on vitality, proliferation, pluripotency, and oxidative stress levels be minimized. In a rat model of Parkinson disease, magnetically labeled mouse embryonic stem cells were tracked by high-field MRI for 6 months. Significant interindividual differences concerning the spatial distribution of cells became evident. Histologically, transplanted green fluorescent protein–positive iron oxide–labeled cells were clearly identified. No significant increase in oxidative stress levels at the implantation site and no secondary uptake of magnetic label by host phagocytotic cells were observed. Our study strongly suggests that molecular MRI approaches must be carefully tailored to the respective cell population to exert minimal physiologic impact, ensuring the feasibility of this imaging approach for clinical applications.

Intravenous iron exacerbates oxidative DNA damage in peripheral blood lymphocytes in chronic hemodialysis patients

Patients undergoing maintenance hemodialysis have elevated markers of oxidative stress, but the reasons for this are not fully understood. Intravenous administration of iron, which many of these patients receive, may provoke the generation of bioactive iron, which enhances oxidative stress and lipid peroxidation. In this study, 110 hemodialysis patients were randomly assigned to five groups that were administered single intravenous doses of iron sucrose, ranging from 20 to 500 mg. A time- and dosage-dependent rise in lymphocyte 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in lymphocyte DNA, a marker of oxidative DNA damage, with a significant increase at 2 h after intravenous iron of > or = 200 mg (P < 0.05). Four weeks later, patients were randomly assigned to weekly iron sucrose (100 mg of elemental iron) or saline for 12 wk, and 89 patients completed the study. Mean lymphocyte 8-OHdG content was significantly higher in patients receiving intravenous iron compared with control subjects (P < 0.05), especially in those with ferritin levels > 500 microg/L. In addition, flow cytometric techniques revealed increased production of reactive oxygen species in lymphocytes among those treated with intravenous iron. Treatment with intravenous iron but not saline was also associated with decreased plasma ascorbate and alpha-tocopherol levels and increased oxidized glutathione/reduced glutathione ratio (P < 0.05). In summary, intravenous iron sucrose provokes oxidative damage to peripheral blood lymphocyte DNA in hemodialysis patients, especially among those with high levels of ferritin.

Oxidative Stress and Inflammation in Chronic Kidney Disease: Role of Intravenous Iron and Vitamin D

Cardiovascular disease (CVD) is the leading cause of death among chronic kidney disease patients (CKD). The etiology of CVD in CKD is multifactorial and increasing evidence points to the important contribution of “nontraditional” risk factors including oxidative stress and inflammation. CKD is associated with a chronic imbalance of prooxidant and antioxidant factors that results in a state of chronic inflammation. Intravenous iron supplementation has been shown to induce oxidative stress and has been associated with lipid peroxidation and DNA damage. Conversely, treatment with vitamin D analogs has been associated with improved mortality in hemodialysis patients in 2 recent large cohort studies. These data suggest that vitamin D analogs may exert effects beyond their pharmacologic role in parathyroid hormone suppression. This article addresses the current data regarding the relative contributions of intravenous iron supplementation and vitamin D analog therapy on oxidative stress and inflammation in CKD patients.

A GSTM3 polymorphism associated with an etiopathogenetic mechanism in Alzheimer disease

Brain-specific glutathione S-transferase Mu 3 (GSTM3) colocalizes with amyloid-beta plaques in Alzheimer's disease (AD). A functional polymorphism rs7483 in GSTM3 may contribute to the decrease in GSTM3 expression in AD. The association of the rs7483 SNP with late-onset AD and mild cognitive impairment (MCI) was evaluated and the impact of a SNP background on gene expression was analyzed in blood mononuclear cells (BMC). The allelic association of the GSTM3 allele with AD was significant in women and in APOEvarepsilon4-negative stratum. A significant association was also found in both MCI and AD subjects with AD family history. GSTM3 transcript levels in BMC were lower in AD than in normal elderly controls, and the presence of the risk allele was associated with further mRNA reduction. Diminished GSTM3 mRNA levels correlated with decreased minichromosome maintenance deficient 3 (MCM3) mRNA levels in a diagnostic and SNP-dependent fashion. Reduced antioxidant defense and genome maintenance associated with the GSTM3 polymorphism suggest a common hub of regulatory networks which, when impaired, may lead to AD.

Iron-induced oxidative stress in haemodialysis patients: a pilot study on the impact of diabetes

BACKGROUND

Administration of intravenous iron preparations in haemodialysis patients may lead to the appearance of non-transferrin bound iron which can catalyse oxidative damage. We investigated this hypothesis by monitoring the oxidative stress of haemodialysis patients and the impact of iron and diabetes mellitus herein.

MATERIALS AND METHODS

Baseline values of serum iron and related proteins, transferrin glycation, non-transferrin bound iron, antioxidant capacity and lipid peroxidation (malondialdehyde) of 11 haemodialysis patients (six non-diabetic and five type 2 diabetes) were compared to those of non-haemodialysis control subjects (non-diabetic and type 2 diabetes). Changes in these parameters were monitored during haemodialysis before and after iron administration.

RESULTS

Baseline values of malondialdehyde correlated with ferritin concentration (r = 0.664, P = 0.036) and were elevated to the same extent in non-diabetic and diabetic haemodialysis patients (median of 1.09 compared to 0.60 mumol/l in control persons, P < 0.02). After iron infusion, transferrin saturation increased more markedly in non-diabetic subjects from 28% to 185% vs. from 33% to 101% in diabetic patients (P = 0.008). This increase was accompanied by the appearance of non-transferrin bound iron (5.91 +/- 1.33 micromol/l), a loss in plasma iron-binding antioxidant capacity and a further increase in malondialdehyde which was more pronounced in diabetic patients (from 0.93 +/- 0.30 micromol/l to 2.21 +/- 0.69 micromol/l vs. from 1.21 +/- 0.42 micromol/l to 1.86 +/- 0.56 micromol/l in the non-diabetic subjects, P = 0.046).

CONCLUSIONS

In haemodialysis patients, higher lipid peroxidation is determined by higher body iron stores. The increase induced by iron infusion is accompanied by a loss in iron-binding antioxidant capacity and is more pronounced in diabetes mellitus.