Enhanced oxidative stress in haemodialysis patients receiving intravenous iron therapy

Molecular and Therapeutic Insights of Alpha-Lipoic Acid as a Potential Molecule for Disease Prevention

Alpha-lipoic acid is an organic, sulfate-based compound produced by plants, humans, and animals. As a potent antioxidant and a natural dithiol compound, it performs a crucial role in mitochondrial bioenergetic reactions. A healthy human body, on the other hand, can synthesize enough α-lipoic acid to scavenge reactive oxygen species and increase endogenous antioxidants; however, the amount of α-lipoic acid inside the body decreases significantly with age, resulting in endothelial dysfunction. Molecular orbital energy and spin density analysis indicate that the sulfhydryl (-SH) group of molecules has the greatest electron donating activity, which would be responsible for the antioxidant potential and free radical scavenging activity. α-Lipoic acid acts as a chelating agent for metal ions, a quenching agent for reactive oxygen species, and a reducing agent for the oxidized form of glutathione and vitamins C and E. α-Lipoic acid enantiomers and its reduced form have antioxidant, cognitive, cardiovascular, detoxifying, anti-aging, dietary supplement, anti-cancer, neuroprotective, antimicrobial, and anti-inflammatory properties. α-Lipoic acid has cytotoxic and antiproliferative effects on several cancers, including polycystic ovarian syndrome. It also has usefulness in the context of female and male infertility. Although α-lipoic acid has numerous clinical applications, the majority of them stem from its antioxidant properties; however, its bioavailability in its pure form is low (approximately 30%). However, nanoformulations have shown promise in this regard. The proton affinity and electron donating activity, as a redox-active agent, would be responsible for the antioxidant potential and free radical scavenging activity of the molecule. This review discusses the most recent clinical data on α-lipoic acid in the prevention, management, and treatment of a variety of diseases, including coronavirus disease 2019. Based on current evidence, the preclinical and clinical potential of this molecule is discussed.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s43450-023-00370-1.

Preliminary experience on the use of sucrosomial iron in hemodialysis: focus on safety, hemoglobin maintenance and oxidative stress

PURPOSE

Iron is usually administered in hemodialysis patients by parenteral route, as oral absorption is poor due to high hepcidin levels. However, administrations of intravenous iron and iron overload are associated with high oxidative stress and systemic inflammation that can affect patient survival. With this study, we evaluated an alternative type of oral iron for the treatment of anemia in hemodialysis patients. The formulation consists in ferric pyrophosphate covered by phospholipids plus sucrose ester of fatty acid matrix, named sucrosomial iron, whose absorption is not influenced by hepcidin.

METHODS

Twenty-four (24) patients undergoing chronic hemodialysis switched iron supplementation from intravenous (ferric gluconate 62.5 mg weekly) to oral (sucrosomial iron, 90 mg weekly in 3 administrations of 30 mg) route for 3 months. Classical anemia, iron metabolism, inflammation and nutritional biomarkers were monitored, as well as biomarkers of oxidative stress, such as protein-bound di-tyrosines, protein carbonylation, advanced oxidation protein products and protein thiols.

RESULTS

Over the 3 months, hemoglobin values remained stable, as the values of hematocrit and mean corpuscular volume. In parallel, other anemia parameters dropped, including ferritin, transferrin saturation and serum iron. On the other side, nutritional biomarkers, such as total proteins and transferrin, increased significantly during the time frame. We also observed a significant decrease in white blood cells as well as a non-significant reduction in C-reactive protein and some oxidative stress biomarkers, such as protein carbonyls and di-tyrosines.

CONCLUSION

Our study demonstrates that a therapy with sucrosomial iron in hemodialysis patients is safe and can maintain stable hemoglobin levels in a three-month period with a possible beneficial effect on oxidative stress parameters. However, the reduction of ferritin and transferrin saturation suggests that a weekly dosage of 90 mg is not sufficient in hemodialysis patients in the long time to maintain hemoglobin.

Prussian blue nanoparticles induce myeloid leukemia cells to differentiate into red blood cells through nanozyme activities

Numerous types of diseases cause serious anemia, which is characterized by a significantly decreased number of circulating red blood cells. The key reason is retarded terminal erythroid differentiation, which is largely involved in the downregulation of intracellular reactive oxygen species (ROS) and insufficient iron uptake. Prussian blue nanoparticles (PBNPs) have been demonstrated to be capable of scavenging ROS via multienzyme-like activity and contain the iron element. The aim of this study was to figure out whether PBNPs can induce terminal erythroid differentiation in myeloid leukemia cells K562 and to investigate the underlying mechanisms. Our results showed that PBNPs were taken up by K562 cells, which reduced the intracellular ROS level in the cells, upregulated the late erythroid surface marker GYPA (CD235a) and downregulated the early erythroid surface marker TFRC (CD71), clearly indicating the occurrence of terminal erythroid differentiation. In addition, the cells became smaller in size after incubation with PBNPs, providing strong side evidence that the cells had undergone terminal differentiation. Mechanistic studies indicated that PBNP-induced terminal differentiation was associated with the upregulation of the nuclear transcriptional factor NFE2 and downregulation of GATA1, both of which are closely related to the variation of intracellular ROS levels. In conclusion, PBNPs demonstrated a novel function by effectively inducing terminal erythroid differentiation in myeloid leukemia cells, which is of great significance in improving the blood profiles of anemia patients.

Oxidation of Unsaturated Phospholipids: A Monolayer Study

Lipid oxidation does strongly influence the self-organization of plasma membranes; the detailed influence is not yet clear. In this work, phospholipid monolayers at the air/water interface were used as model membranes. Oxidation was induced by the reactive oxygen species formed in a H₂O₂-enriched solution. The reaction was found to be diffusion-limited; the concentration of the reactive oxygen species was about 50 nM. Isotherms were recorded for different phosphatidylcholines with saturated and unsaturated acyl chains. For unsaturated lipids, the isotherms showed a constant relative molecular area increase after oxidization, independent of the molecular area and dependent on the degree of peroxidation. Similarly, the compressibility modulus was unchanged, but shifted to larger molecular areas. The correlation between peroxidation and changes of the interaction forces between the lipid molecules is discussed.

Labile plasma iron levels in chronic hemodialysis patients treated by intravenous iron supplementation

The increased usage of intravenous iron in hemodialysis patients during recent years has led to increasing concern over the potential development of iron overload. Current methods for detecting iron overload, transferrin saturation, and serum ferritin are neither sensitive nor specific. Labile plasma iron (LPI) represents a component of nontransferrin-bound iron and may be a more accurate indicator of impending iron overload. We studied whether LPI measured can serve as an early indicator of impending iron overload and mortality in hemodialysis patients. Chronic hemodialysis patients from two medical centers in Israel and Poland who received intravenous iron were included. Baseline clinical and laboratory parameters were recorded. LPI was measured before and 48 hours after a single IV administration. Correlation of positive LPI with laboratory parameters and 2-year mortality was evaluated. One hundred and one hemodialysis patients were included in the study. LPI became positive post-administration in 18 (17.8%) patients. Ferritin levels >526 ng/mL and monthly iron doses >250 mg were associated with positive LPI after intravenous iron. At a 2-year follow-up, higher mortality was observed in the positive LPI group (61.1% compared to 25.3%, P ≤ .05), although this effect was not statistically significant after multivariate adjustment. A substantial number of hemodialysis patients have positive LPI after intravenous iron administration. LPI positively correlates with laboratory parameters that are currently in routine clinical use for detecting iron overload and with higher intravenous iron dose. Further studies should be conducted to establish the clinical implications of LPI monitoring in hemodialysis patients.

Oxidative Stress in Hemodialysis Pediatric Patients

BACKGROUND:

Oxidative stress may play a role in complications of hemodialysis patients as atherosclerosis, thrombosis, and inflammation.

AIM:

The aim of the study was to evaluate the oxidative stress in hemodialysis pediatric patients through measurement of oxidative stress enzymes as paraoxanase activity (PON), arylesterase activity (ASA), superoxide dismutase (SOD) and also non-enzymatic antioxidant vitamins as vitamins A, C and E levels.

METHODS:

The study included 50 hemodialysis pediatric patients with mean age 11.4 ± 5.4 years and 30 normal children of matched sex and age as a control group. Assessment of oxidative stresses was done using ELIZA technique.

RESULTS:

SOD, ASA, and vitamin C were significantly lower among hemodialysis patients in comparison to control group (p = 0.004, 0.004, > 0.001 respectively).

CONCLUSION:

The study concluded that oxidative stress was common finding in hemodialysis pediatric patients which may play a role in complications encountered among these patients.

Protective Role of Histidine Supplementation Against Oxidative Stress Damage in the Management of Anemia of Chronic Kidney Disease

Anemia is a major health condition associated with chronic kidney disease (CKD). A key underlying cause of this disorder is iron deficiency. Although intravenous iron treatment can be beneficial in correcting CKD-associated anemia, surplus iron can be detrimental and cause complications. Excessive generation of reactive oxygen species (ROS), particularly by mitochondria, leads to tissue oxidation and damage to DNA, proteins, and lipids. Oxidative stress increase in CKD has been further implicated in the pathogenesis of vascular calcification. Iron supplementation leads to the availability of excess free iron that is toxic and generates ROS that is linked, in turn, to inflammation, endothelial dysfunction, and cardiovascular disease. Histidine is indispensable to uremic patients because of the tendency toward negative plasma histidine levels. Histidine-deficient diets predispose healthy subjects to anemia and accentuate anemia in chronic uremic patients. Histidine is essential in globin synthesis and erythropoiesis and has also been implicated in the enhancement of iron absorption from human diets. Studies have found that L-histidine exhibits antioxidant capabilities, such as scavenging free radicals and chelating divalent metal ions, hence the advocacy for its use in improving oxidative stress in CKD. The current review advances and discusses evidence for iron-induced toxicity in CKD and the mechanisms by which histidine exerts cytoprotective functions.

The Impact of Iron Overload in Acute Leukemia: Chronic Inflammation, But Not the Presence of Nontransferrin Bound Iron is a Determinant of Oxidative Stress

In the literature, studies on the oxidant effects of nontransferrin bound iron [NTBI (eLPI assay)] during chemotherapy of acute lymphoblastic leukemia and acute myeloblastic leukemia are lacking. We established NTBI and oxidative stress determinants (OSD), iron parameters, high-sensitive C-reactive protein (hs-CRP) levels, liver tests, cumulative chemotherapeutic doses, and transfused blood in 36 children with acute leukemia throughout chemotherapy. These parameters were determined at the beginning and end of chemotherapy blocks (11 time points) and in 20 healthy children using enzyme-linked immunosorbent assay, and colorimetric and fluorometric enzymatic methods. In acute lymphoblastic leukemia, NTBI, OSD, and hs-CRP were higher than controls at 4/11, 7/11, and 9/11 time points (P<0.05). At 3 time points, NTBI and OSD concurrently increased. Ferritin, soluble transferrin receptor, serum iron, and transferrin saturation were higher than in controls at 5 to 11/11 time points (P<0.05). Those with NTBI had higher iron parameters than those without NTBI (P<0.05), but showed similar OSD, hs-CRP, liver enzymes, cumulative chemotherapeutics, and transfused blood (P>0.05). OSD did not correlate with NTBI, but correlated with hs-CRP. In conclusion, NTBI is a poor predictor of OSD in acute leukemia possibly because of the heterogeneity of NTBI and chronic inflammation. Further studies are needed to delineate the pathophysiology of these diseases.

The Ferumoxytol for Anemia of CKD Trial (FACT)-a randomized controlled trial of repeated doses of ferumoxytol or iron sucrose in patients on hemodialysis: background and rationale

Background

Iron deficiency anemia (IDA) is a common manifestation of chronic kidney disease (CKD), affecting most patients on hemodialysis and imposing a substantial clinical burden. Treatment with iron supplementation increases hemoglobin levels and can reduce the severity of anemia in patients with CKD. While correcting anemia in these patients is an important therapeutic goal, there is a lack of long-term trials directly comparing intravenous iron therapies in patients with CKD receiving hemodialysis.

Methods/Design

The Ferumoxytol for Anemia of CKD Trial (FACT) is a 13-month, open-label, randomized, multicenter, international, prospective study with 2 substudies. Entry criteria for the main study include adults with IDA (defined as hemoglobin <11.5 g/dL [<115.0 g/L] and a transferrin saturation <30%), serum ferritin <800 ng/mL (<1798 pmol/L), and receiving hemodialysis for ≥3 months. Patients are randomized to receive ferumoxytol (1.02 g over 2 doses) or iron sucrose (1.0 g over 10 doses) during the initial 5-week treatment period. Those with persistent/recurrent IDA over the 11-month observation period will receive additional 5-week treatment periods, as appropriate. The primary efficacy endpoint of the main study is the mean change in hemoglobin from Baseline to Week 5 for each treatment period. The secondary efficacy endpoints include the mean change in transferrin saturation from Baseline to Week 5 and the proportion of patients with a hemoglobin increase of ≥1.0 g/dL at any time from Baseline to Week 5. Safety will be assessed through an examination of the adverse event profile over the course of the study. An “oxidative stress” substudy in approximately 100 patients will assess the effects of treatment on biomarkers of oxidative stress/inflammation during the initial 5-week treatment period, and a magnetic resonance imaging substudy in approximately 70 patients will assess the potential for iron deposition in target tissues over 24 months.

Discussion

FACT fulfills the need for a long-term comparative trial in patients with IDA and CKD receiving hemodialysis. The efficacy and safety results will provide useful information for guiding therapy in this population. Two hundred ninety-six patients have been enrolled, and completion of the main study is expected soon.

Trial registration

ClinicalTrials.gov identifier: NCT01227616 (registered October 22, 2010); EudraCT number: 2010-022133-28

Ferritin Elevation and Improved Responsiveness to Erythropoiesis-Stimulating Agents in Patients on Ferric Citrate Hydrate

Introduction

In hemodialysis patients on ferric citrate hydrate, the increase in ferritin level is mainly due to the administration of the compound. We investigated possible other factors associated with ferritin level and how erythropoietin resistance index and erythropoiesis in those patients were affected. We looked at ferritin-elevating factors using data from a Japanese phase III long-term clinical trial of ferric citrate hydrate.

Methods

The factors with a strong association with ferritin levels at week 28 were selected by the process of variable selection. In addition, selected factors were analyzed by Mixed Model for Repeated Measurement. Subjects were divided into 3 groups by quantiles (<Q1, Q1-Q3, Q3<) of the most strongly correlated factors. Then the least-squares means of change of ferritin at each time point for each group were calculated. Finally, the differences of the least-squares means were examined. Changes of both erythropoiesis-stimulating agent dose and erythropoietin resistance index for each group were investigated. The differences in mean erythropoietin resistance index between groups at baseline, week 28, and week 52 were analyzed using t tests.

Results

Dose of ferric citrate hydrate showed the strongest correlation with change of ferritin and the second strongest was the reduction of erythropoiesis-stimulating agents. The mean erythropoietin resistance index was lowered in group <Q1. Group <Q1 showed significantly lower levels of ferritin at baseline.

Discussion

It is suggested that not only iron load but also the erythropoiesis-stimulating agent dose reduction may be involved in ferritin elevation during ferric citrate hydrate treatment, resulting in a decrease of erythropoietin resistance index.

Risk of Infection with Intravenous Iron Therapy

Objective:

To review the potential risks of administering intravenous iron to patients with infection.

Data Sources:

Literature was accessed through MEDLINE (1977–June 2007) and Google Scholar, using the terms intravenous iron, iron sucrose, ferric gluconate, iron dextran, and infection. In addition, reference citations from publications identified were reviewed.

Study Selection and Data Extraction:

All English-language articles identified from the data sources were evaluated. Studies that provided data relevant to the objective were used, including in vitro and animal studies.

Data Synthesis:

The role of iron in bacterial growth and the pathophysiology of cellular immunity create legitimate, yet theoretical, concerns that active infection may be exacerbated by the administration of intravenous iron. Human data relating to this issue are limited. A few small, human studies in a population with chronic kidney disease suggest a possible increased risk of developing an infection associated with intravenous iron; however, prospective human data directly linking intravenous iron to exacerbation of existing infection or infection-related mortality are lacking. In vitro data suggest that increased transferrin saturation related to iron administration may result in polymorphonuclear leukocyte dysfunction and decreased inhibition of bacterial growth. Sparse animal data have linked intravenous iron therapy with morbidity and mortality in sepsis models.

Conclusions:

Despite the limited human data, careful consideration of risk versus benefit should be used when administering intravenous iron to patients with ongoing infection. Additional clinical data are needed to determine whether intravenous iron administration worsens outcomes of patients with infection.

Endothelial Injury Markers With High-dose IntravenousIron Therapy in Renal Failure

Endothelial injury is prevalent in patients with chronic renal failure (CRF) and may be exacerbated by commonly used intravenous (IV) iron therapy. The effects of high-dose IV iron sucrose treatment (200 mg daily in 250 mL of 0.9% saline, administered over 1 hour, median treatment duration 5 days) on circulating endothelium and/or tissue injury markers such as hepatocyte growth factor, thrombomodulin, von Willebrand factor, and C-reactive protein levels were studied. The markers were determined in 24 anemic (mean hemoglobin 9.48 g/dL) pre-dialysis (median creatinine clearance 21.5 mL/min) patients with CRF and defined absolute and/or functional iron deficiency. The measurements were performed before iron administration and 24 hours after the last infusion. All the markers remained unchanged following the IV iron therapy (all p < 0.172); no thrombotic or other adverse effects were observed. In conclusion, the above high-dose IV iron sucrose supplementation does not cause evident endothelial or other tissue injury in patients with CRF, and is clinically safe.

Red blood cell abnormalities and the pathogenesis of anemia in end-stage renal disease

Anemia is the most common hematologic complication in end-stage renal disease (ESRD). It is ascribed to decreased erythropoietin production, shortened red blood cell (RBC) lifespan, and inflammation. Uremic toxins severely affect RBC lifespan; however, the implicated molecular pathways are poorly understood. Moreover, current management of anemia in ESRD is controversial due to the "anemia paradox" phenomenon, which underlines the need for a more individualized approach to therapy. RBCs imprint the adverse effects of uremic, inflammatory, and oxidative stresses in a context of structural and functional deterioration that is associated with RBC removal signaling and morbidity risk. RBCs circulate in hostile plasma by raising elegant homeostatic defenses. Variability in primary defect, co-morbidity, and therapeutic approaches add complexity to the pathophysiological background of the anemic ESRD patient. Several blood components have been suggested as biomarkers of anemia-related morbidity and mortality risk in ESRD. However, a holistic view of blood cell and plasma modifications through integrated omics approaches and high-throughput studies might assist the development of new diagnostic tests and therapies that will target the underlying pathophysiologic processes of ESRD anemia.

Correlation of bioelectrical impedance analysis phase angle with changes in oxidative stress on end-stage renal disease patients, before, during, and after dialysis

Chronic kidney disease is a condition that promotes oxidative stress. There are conflicting evidence about the role of hemodialysis on oxidative stress, that are mostly related with the various types of membrane materials used, the quality and type of dialysate, the method used, etc. The phase angle (PhA), which is determined with bioelectrical impedance analysis (BIA), measures the functionality of cell membranes. In this study, the correlation of the PhA with parameters of oxidative stress is attempted for the first time. We evaluated parameters of oxidative status as total antioxidant capacity (TAC) in erythrocytes (RBCs) and plasma of patients with ESRD undergoing hemodialysis with low flux synthetic polysulfone membranes. Measurements were recorded from 30 patients (16 men and 14 women) aged 64 ± 14 years before, during, and after dialysis, and in 15 healthy volunteers aged 56 ± 12 years The PhA was obtained by BIA. The plasma TAC increased significantly (41%, p < 0.05). Intracellular TAC noted a non-significant increase. Total antioxidant capacity of the patients before and after hemodialysis was significantly lower from the healthy volunteers (p < 0.05) showing that ESRD patients are at the state of increased oxidative stress. The PhA increased in significantly positive correlation with plasma TAC at the end of hemodialysis. The process of hemodialysis with biocompatible synthetic membranes and bicarbonate dialysate improved plasma TAC. The positive correlation of PhA with extracellular TAC could evolve to a method of oxidative stress estimation by BIA but further research is needed.

Serum ferritin is associated with arterial stiffness in hemodialysis patients: results of a 3-year follow-up study

BACKGROUND

Iron may contribute to vascular injury through reactive oxygen species. Hemodialysis patients frequently receive iron supply for correction of anemia and are at a high risk of cardiovascular disease. We tested the relationship between iron status and change in arterial stiffness in hemodialysis patients.

PATIENTS AND METHODS

We measured iron status in 53 hemodialysis patients and studied the association with clinical, biochemical, and arterial stiffness measured by brachial-ankle pulse wave velocity (baPWV) over 3 years. The blood pressure was controlled to below 140/90 mmHg by anti-hypertensive drugs.

RESULTS

Median and interquartile range of baseline baPWV, baPWV at 3 years, and ΔbaPWV (difference between 3-year baPWV and baseline baPWV) were following: 17.6 (14.8-18.9), 16.9 (15.3-19.9), and 0.2 (-1.2 to 2.7) m/s. At baseline, baPWV was positively correlated with age, serum ferritin, and systolic blood pressure in univariate analysis. However, in multivariate analysis, only age and serum ferritin remained the significant determinants of baseline baPWV. After 3 years, ΔbaPWV was negatively correlated with age and positively with 3-year averaged serum ferritin in univariate analysis. Then, in multivariate analysis, only 3-year averaged serum ferritin was the important determinant of ΔbaPWV. ΔbaPWV was significantly increased in patients with 3-year averaged serum ferritin >500 ng/mL compared to patients with 3-year averaged serum ferritin ≤500 ng/mL.

CONCLUSIONS

In hemodialysis patients, serum ferritin associates with the progressive arterial stiffness, especially when serum ferritin >500 ng/mL.

Effects of carnitine on oxidative stress response to intravenous iron administration to patients with CKD: impact of haptoglobin phenotype

BACKGROUND

Anemia is a common disorder in CKD patients. It is largely attributed to decreased erythropoietin (EPO) production and iron deficiency. Therefore, besides EPO, therapy includes iron replenishment. However, the latter induces oxidative stress. Haptoglobin (Hp) protein is the main line of defense against the oxidative effects of Hemoglobin/Iron. There are 3 genotypes: 1-1, 2-1 and 2-2. Hp 2-2 protein is inferior to Hp 1-1 as antioxidant. So far, there is no evidence whether haptoglobin phenotype affects iron-induced oxidative stress in CKD patients. Therefore, the present study examines the influence of carnitine treatment on the intravenous iron administration (IVIR)-induced oxidative stress in CKD patients, and whether Hp phenotype affects this response.

METHODS

TRIAL REGISTRATION

Current Controlled Trials ISRCTN5700858. This study included 26 anemic (Hb = 10.23 ± 0.28) CKD patients (stages 3-4) that were given a weekly IVIR (Sodium ferric gluconate, [125 mg/100 ml] for 8 weeks, and during weeks 5-8 also received Carnitine (20 mg/kg, IV) prior to IVIR. Weekly blood samples were drawn before and after each IVIR for Hp phenotype, C-reactive protein (CRP), advanced oxidative protein products (AOPP), neutrophil gelatinase-associated lipocalin (NGAL), besides complete blood count and biochemical analyses.

RESULTS

Eight percent of CKD patients were Hp1-1, 19 % Hp2-1, and 73 % Hp2-2. IVIR for 4 weeks did not increase hemoglobin levels, yet worsened the oxidative burden as was evident by elevated plasma levels of AOPP. The highest increase in AOPP was observed in Hp2-2 patients. Simultaneous administration of Carnitine with IVIR abolished the IVIR-induced oxidative stress as evident by preventing the elevations in AOPP and NGAL, preferentially in patients with Hp2-2 phenotype.

CONCLUSIONS

This study demonstrates that Hp2-2 is a significant risk factor for IVIR-induced oxidative stress in CKD patients. Our finding, that co-administration of Carnitine with IVIR preferentially attenuates the adverse consequences of IVIR, suggests a role for Carnitine therapy in these patients.

The Labile Side of Iron Supplementation in CKD

The practice of intravenous iron supplementation has grown as nephrologists have gradually moved away from the liberal use of erythropoiesis-stimulating agents as the main treatment for the anemia of CKD. This approach, together with the introduction of large-dose iron preparations, raises the future specter of inadvertent iatrogenic iron toxicity. Concerns have been raised in original studies and reviews about cardiac complications and severe infections that result from long-term intravenous iron supplementation. Regarding the iron preparations specifically, even though all the currently available preparations appear to be relatively safe in the short term, little is known regarding their long-term safety. In this review we summarize current knowledge of iron metabolism with an emphasis on the sources and potentially harmful effects of labile iron, highlight the approaches to identifying labile iron in pharmaceutical preparations and body fluids and its potential toxic role as a pathogenic factor in the complications of CKD, and propose methods for its early detection in at-risk patients.

Wishful Thinking: The Surprisingly Sparse Evidence for a Relationship between Oxidative Stress and Cardiovascular Disease in Hemodialysis Patients

The increased frequency of cardiovascular disease observed in hemodialysis patients is secondary to the combination of many traditional (age, male sex, hypertension, smoking, diabetes mellitus, and dyslipidemia) and novel and uremia-related (inflammation, uremic toxins, adipokine imbalance, coagulation disorders, protein-energy wasting, volume overload, endothelial dysfunction, hyperparathyroidism, and subclinical hypothyroidism) risk factors. Usually, in the latter group, oxidative stress is included. However, after decades of research, it remains essentially unknown if oxidative stress has a causative role in the development of cardiovascular disease in long-term hemodialysis patients because adequate longitudinal studies are lacking. Data deriving from cross-sectional studies suggest that biomarkers of oxidative stress are associated with cardiovascular disease prevalence. Conversely, conflicting and inconclusive results have been obtained on the association between oxidative stress and coronary artery calcification, atherosclerosis, and all-cause and cardiovascular disease-related outcome. It is desirable that further studies are conducted on this topic in the near future.

Long-term safety and efficacy of a novel iron-containing phosphate binder, JTT-751, in patients receiving hemodialysis

OBJECTIVE

JTT-751 is a novel phosphate binder containing ferric citrate as the active ingredient. This study investigated long-term safety and efficacy of JTT-751 for hyperphosphatemia in patients receiving hemodialysis.

DESIGN AND METHODS

This was 52-week, phase 3, multicenter, open-label, dose titration, long-term study. All patients were receiving thrice-weekly hemodialysis for ≥3 months before the initiation of the study. JTT-751 was given at titrated doses between 1.5 and 6.0 g/day.

MAIN OUTCOME MEASURES

Safety endpoints were adverse events and adverse drug reactions. Efficacy outcomes were the change in serum phosphate, corrected serum calcium, and intact parathyroid hormone. Changes in ferritin, transferrin saturation, and doses of erythropoiesis-stimulating agents (ESAs) and intravenous iron formulations were additional outcomes.

RESULTS

One hundred and eighty patients were included in the trial. Dose-titrated JTT-751 decreased mean serum phosphate after administration and satisfactorily maintained serum phosphate concentrations throughout the entire duration of the 52-week trial. Mean serum phosphate concentrations were kept lower than 5.5 mg/dL from weeks 5 to 52. The most common adverse events were gastrointestinal disorders, which were mild to moderate in intensity. Serum ferritin concentrations rose to a peak around week 28 and stabilized thereafter. The mean intravenous iron dose decreased from 57.3 mg/4 weeks (weeks 0-12) to 3.6 mg/4 weeks (weeks 28-52); weekly ESA dose declined by 25% over the same time frame, while mean hemoglobin concentrations remained stable.

CONCLUSION

JTT-751 1.5-6.0 g/day controls serum phosphorus concentrations and reduces the need for ESAs and intravenous iron in patients receiving hemodialysis.

[Importance of selenium homeostasis in chronic and end-stage kidney diseases]

Selenium is an essential trace element for the human body with a significant antioxidant effect. Selenium deficiency and excess are both detrimental for proper functioning of the human body. The possible association between selenium deficiency and acute or chronic renal disease, along with their complications has been less intensively investigated, however, there are firm data showing that selenium deficiency and renal failure increase the risk of both coronary artery disease and total mortality. Further studies revealed that selenium deficiency increases the risk of death due to infection in patients treated with hemodialysis through dysfunction of the immune system. However, there are no data whether the imbalance of selenium metabolism, especially selenium deficiency, could cause chronic kidney disease or renal failure. As far as results of selenium measurements, there is convincing evidence that protein loss and renal replacement treatment reduce serum selenium levels. Despite some contradictory results obtained from various studies regarding selenium deficiency in chronic kidney diseases, it seems that selenium supplementation may be beneficial in many patients with severe or end-stage kidney disease including those treated with dialysis.

Effect of α -Lipoic Acid on Oxidative Stress in End-Stage Renal Disease Patients Receiving Intravenous Iron

Oxidative stress is associated with increased risk of cardiovascular disease in end-stage renal disease (ESRD) patients. Intravenous (IV) iron has been shown to increase oxidative stress. The aim of the study was to evaluate changes in oxidative stress markers following administration of IV sodium ferric gluconate (SFG) to ESRD patients with and without administration of the antioxidant, α -lipoic acid. This is an open-label, crossover study. 125 mg of IV SFG was administered during control (C) and intervention (I) visits. During the I visit, 600 mg of α -lipoic acid was given orally prior to IV SFG. Blood samples were collected at defined time periods for F2-isoprostane (FIP), lipid hydroperoxide (LHP), malondialdehyde (MDA), and iron indices. We recruited ten African-American ESRD subjects: 50% male; mean age 45 ± 9 years; mean hemoglobin 13 ± 1 g/dL; ferritin 449 ± 145 ng/mL; transferrin saturation 27 ± 4%. There were no significant differences in iron indices between the two visits after IV SFG. MDA, FIP, and LHP increased significantly for both C and I visits with a greater increase in the I group. Administration of IV SFG results in an acute rise in oxidative stress in ESRD patients. In contrast to previous studies, administration of α -lipoic acid was associated with a greater increase in oxidative stress.

The complex interplay of iron metabolism, reactive oxygen species, and reactive nitrogen species: insights into the potential of various iron therapies to induce oxidative and nitrosative stress

Production of minute concentrations of superoxide (O2(*-)) and nitrogen monoxide (nitric oxide, NO*) plays important roles in several aspects of cellular signaling and metabolic regulation. However, in an inflammatory environment, the concentrations of these radicals can drastically increase and the antioxidant defenses may become overwhelmed. Thus, biological damage may occur owing to redox imbalance-a condition called oxidative and/or nitrosative stress. A complex interplay exists between iron metabolism, O2(*-), hydrogen peroxide (H2O2), and NO*. Iron is involved in both the formation and the scavenging of these species. Iron deficiency (anemia) (ID(A)) is associated with oxidative stress, but its role in the induction of nitrosative stress is largely unclear. Moreover, oral as well as intravenous (iv) iron preparations used for the treatment of ID(A) may also induce oxidative and/or nitrosative stress. Oral administration of ferrous salts may lead to high transferrin saturation levels and, thus, formation of non-transferrin-bound iron, a potentially toxic form of iron with a propensity to induce oxidative stress. One of the factors that determine the likelihood of oxidative and nitrosative stress induced upon administration of an iv iron complex is the amount of labile (or weakly-bound) iron present in the complex. Stable dextran-based iron complexes used for iv therapy, although they contain only negligible amounts of labile iron, can induce oxidative and/or nitrosative stress through so far unknown mechanisms. In this review, after summarizing the main features of iron metabolism and its complex interplay with O2(*-), H2O2, NO*, and other more reactive compounds derived from these species, the potential of various iron therapies to induce oxidative and nitrosative stress is discussed and possible underlying mechanisms are proposed. Understanding the mechanisms, by which various iron formulations may induce oxidative and nitrosative stress, will help us develop better tolerated and more efficient therapies for various dysfunctions of iron metabolism.

Immunological abnormalities associated with hereditary haemorrhagic telangiectasia

OBJECTIVE

Hereditary haemorrhagic telangiectasia (HHT) is a genetic disorder related to mutations in one of the coreceptors to the transforming growth factor-β superfamily (ALK1 or endoglin). Besides the obvious vascular symptoms (epistaxis and arteriovenous malformations), patients have an unexplained high risk of severe bacterial infections. The aim of the study was to assess the main immunological functions of patients with HHT using the standard biological tests for primary immunodeficiencies.

DESIGN, SETTING AND SUBJECTS

A prospective single-centre study of 42 consecutive adult patients with an established diagnosis of HHT was conducted at the National French HHT Reference Center (Lyon). Lymphocyte subpopulations and proliferation capacity, immunoglobulin levels and neutrophil and monocyte phagocytosis, oxidative burst and chemotaxis were assessed.

RESULTS

Innate immunity was not altered in patients with HHT. With regard to adaptive immunity, significant changes were seen in immunological parameters: primarily, a lymphopenia in patients with HHT compared with healthy control subjects affecting mean CD4 (642 cells μL(-1) vs. 832 cells μL(-1) , P < 0.001), CD8 (295 cells μL(-1) vs. 501 cells μL(-1) , P < 0.0001) and natural killer (NK) cells (169 cells μL(-1) vs. 221 cells μL(-1) , P < 0.01), associated with increased levels of immunoglobulins G and A. This lymphopenia mainly concerned naïve T cells. Proliferation capacities of lymphocytes were normal. Lymphopenic patients had a higher frequency of iron supplementation but no increase in infection rate. Lower levels of immunoglobulin M and a higher rate of pulmonary arteriovenous malformations were found amongst patients with a history of severe infection.

CONCLUSIONS

Patients with HHT exhibit immunological abnormalities including T CD4, T CD8 and NK cell lymphopenia and increased levels of immunoglobulins G and A. The observed low level of immunoglobulin M requires further investigation to determine whether it is a specific risk factor for infection in HHT.

Pomegranate juice intake attenuates the increase in oxidative stress induced by intravenous iron during hemodialysis

The hemodialysis (HD) procedure induces oxidative stress (OS), which is further aggravated by intravenous (IV) iron administration, aimed at correcting anemia of patients with HD. We have recently shown that 1 year of pomegranate juice (PJ) intake attenuated OS and inflammation in patients with HD. In the current study, we hypothesized that a single dose of PJ can attenuate the enhanced OS and inflammation induced by both the dialysis procedure and IV iron administration during HD session. Twenty-seven patients with HD were randomized to receive PJ or placebo during 1 dialysis session with IV iron. Blood samples were drawn before and after the session to asses OS biomarkers such as advanced oxidation protein products and myeloperoxidase (MPO), whereas polymorphonuclear leukocyte (PMNL) counts served as an indirect measure of inflammation. At the end of the dialysis session, an increase in advanced oxidation protein products and MPO levels as well as a decrease in PMNLs counts were observed in the placebo group, whereas no significant changes occurred in the PJ group. The postdialysis increase in MPO levels in the placebo group is a direct result of PMNL degranulation, associated with postdialysis decrease in PMNL counts. Degranulation of PMNLs leads to the release of other cell moieties, such as inflammatory mediators and proteases that enhance inflammation. We conclude that PJ intake attenuated the increase in systemic OS and inflammation induced by IV iron administration during the dialysis session. These beneficial effects illuminate the previously observed attenuation in OS and inflammation in patients with HD on prolonged PJ intake.

Defected red blood cell membranes and direct correlation with the uraemic milieu: the connection with the decreased red blood cell lifespan observed in haemodialysis patients

Together with impaired production of erythropoietin and iron deficiency, the decreased lifespan of red blood cells (RBCs) is a main factor contributing to the chronic anaemia observed in haemodialysis (HD) patients. Atomic force microscopy is employed in this work to thoroughly survey the membrane of intact RBCs (iRBCs) of HD patients in comparison to those of healthy donors, aiming to obtain direct information on the structural status of RBCs that can be related to their decreased lifespan. We observed that the iRBC membrane of the HD patients is overpopulated with extended circular defects, termed 'orifices', that have typical dimension ranging between 0.2 and 1.0 μm. The 'orifice' index-that is, the mean population of 'orifices' per top membrane surface-exhibits a pronounced relative increase of order 54 ± 12% for the HD patients as compared to healthy donors. Interestingly, for the HD patients, the 'orifice' index, which relates to the structural status of the RBC membrane, correlates strongly with urea concentration, which is a basic index of the uraemic milieu. Thus, these results indicate that the uraemic milieu downgrades the structural status of the RBC membrane, possibly triggering biochemical processes that result in their premature elimination from the circulation. This process could decrease the lifespan of RBCs, as observed in HD patients.

Association between circulating electronegative low-density lipoproteins and serum ferritin in hemodialysis patients: a pilot study

BACKGROUND

Iron supplementation is a common recommendation to chronic kidney disease patients undergoing hemodialysis (HD). However, iron excess is closely associated with lipid peroxidation and, it is well known that electronegative low-density lipoproteins (LDL[-]) are present at higher plasma concentrations in diseases with high cardiovascular risk such as chronic kidney disease. Thus, the aim of this study was to investigate whether ferritin levels are associated with LDL(-) levels in HD patients.

DESIGN

This was a cross-sectional study.

SETTING

This study was conducted from a private clinic in Rio de Janeiro, Brazil.

PATIENTS

The study included 27 HD patients and 15 healthy subjects.

METHODS AND PROCEDURES

Twenty-seven HD patients (14 men, 58.6 ± 10 years, 62.2 ± 51.4 months on dialysis, and body mass index: 24.4 ± 4.2 kg/m(2)) were studied and compared with 15 healthy individuals (6 men, 53.8 ± 15.4 years, body mass index: 24.5 ± 4.3 kg/m(2)). Serum LDL(-) levels were measured using the enzyme-linked immunosorbent assay method; ferritin levels by commercially available kits, and tumor necrosis factor-α, interleukin-6, monocyte chemoattractant protein-1, and plasminogen activator inhibitor-1 were determined with a multiplex assay kit manufactured by R&D Systems.

RESULTS

The HD patients presented higher LDL(-) and tumor necrosis factor-α levels (0.15 ± 0.13 U/L and 5.9 ± 2.3 pg/mL, respectively) than healthy subjects (0.07 ± 0.05 U/L and 2.3 ± 1.3 pg/mL, respectively) (P = .0001). The mean ferritin level in HD patients was 1,117.5 ± 610.4 ng/mL, and 90% of patients showed ferritin levels exceeding 500 ng/mL. We found a positive correlation between LDL(-) and ferritin in the patients (r = 0.48; P = .01), and ferritin was a significant contributor to LDL(-) concentrations independent of inflammation.

CONCLUSIONS

Excess body iron stores for HD patients was associated with signs of increased oxidative stress, as reflected by increased LDL(-) levels in HD patients.

Utilization Patterns of IV Iron and Erythropoiesis Stimulating Agents in Anemic Chronic Kidney Disease Patients: A Multihospital Study

Intravenous (IV) iron and Erythropoiesis Stimulating Agents (ESAs) are recommended for anemia management in chronic kidney disease (CKD). This retrospective cohort study analyzed utilization patterns of IV iron and ESA in patients over 18 years of age admitted to University Health System Hospitals with a primary or secondary diagnosis of CKD between January 1, 2006 to December 31, 2008. A clustered binomial logistic regression using the GEE methodology was used to identify predictors of IV iron utilization. Only 8% (n = 6678) of CKD patients on ESA therapy received IV iron supplementation in university hospitals. Those receiving iron used significantly less amounts of ESAs. Patient demographics (age, race, primary payer), patient clinical conditions (admission status, severity of illness, dialysis status), and physician specialty were identified as predictors of IV iron use in CKD patients. Use of IV iron with ESAs was low despite recommendations from consensus guidelines. The low treatment rate of IV iron represents a gap in treatment practices and signals an opportunity for healthcare improvement in CKD anemic patients.

Ischemia modified albumin and carbonyl protein as potential biomarkers of protein oxidation in hemodialysis

OBJECTIVE

The aim of this study was to evaluate the effect of HD on ischemia modified albumin (IMA) and protein carbonyl groups in order to investigate the role of IMA as a marker of protein oxidation.

DESIGN AND METHODS

This study was conducted with 23 chronic hemodialysis patients. The serum IMA levels and protein carbonyl groups were measured immediately before hemodialysis (pre-HD) and after the end of hemodialysis (post-HD).

RESULTS

IMA concentrations were significantly higher in post-HD than those of the pre-HD and carbonyl protein concentrations were higher in post-HD in comparison with pre-HD. A significant correlation was observed between IMA and carbonyl protein levels.

CONCLUSIONS

The increase of IMA levels and protein carbonyl groups post-HD could be attributed to the increase of oxidative stress associated with HD, and IMA appears to be an important biomarker for assessing protein oxidation after HD.

Lack of non-transferrin-bound iron in heart transplant recipients

BACKGROUND

Labile plasma iron (LPI) is a heterogeneous fraction thought to be composed of iron bound to serum albumin, citrate, and other undefined negatively charged ligands called non-transferrin-bound iron (NTBI). It is associated with formation of reactive oxygen species which are implicated in the pathogenesis of myocardial infarction and bacterial infection. Therefore, the measurement of NTBI could serve as an early marker for reactive oxygen species-induced tissue damage. In this study, we assessed the prevalence of NTBI in heart transplant recipients.

METHODS

Complete blood counts, urea, serum lipids, fasting glucose, creatinine, and N-terminal pro-B-type natriuretic peptide were studied by standard laboratory methods in the central laboratory of the hospital. Soluble transferrin receptor was measured using kits from R&D (Abington, UK) and interleukin-6 with kits from Diaclone (Germany). NTBI was assessed in Israel by Aferrix Ltd; LPI≤0.4 units was considered to be negative.

RESULTS

In all of the studied patients, NTBI was negative. In the 15 healthy volunteers, all the results were negative.

CONCLUSIONS

In heart allograft recipients there is no evidence of reactive oxygen species-induced tissue damage due to either iron overload from oversupplementation or excessive blood transfusion. However, this particular adverse effect should be taken into account when considering treatment of anemia with iron and/or red blood cell transfusions.

New rat models of iron sucrose-induced iron overload

The majority of murine models of iron sucrose-induced iron overload were carried out in adult subjects. This cannot reflect the high risk of iron overload in children who have an increased need for iron. In this study, we developed four experimental iron overload models in young rats using iron sucrose and evaluated different markers of iron overload, tissue oxidative stress and inflammation as its consequences. Iron overload was observed in all iron-treated rats, as evidenced by significant increases in serum iron indices, expression of liver hepcidin gene and total tissue iron content compared with control rats. We also showed that total tissue iron content was mainly associated with the dose of iron whereas serum iron indices depended essentially on the duration of iron administration. However, no differences in tissue inflammatory and antioxidant parameters from controls were observed. Furthermore, only rats exposed to daily iron injection at a dose of 75 mg/kg body weight for one week revealed a significant increase in lipid peroxidation in iron-treated rats compared with their controls. The present results suggest a correlation between iron overload levels and the dose of iron, as well as the duration and frequency of iron injection and confirm that iron sucrose may not play a crucial role in inflammation and oxidative stress. This study provides important information about iron sucrose-induced iron overload in rats and may be useful for iron sucrose therapy for iron deficiency anemia as well as for the prevention and diagnosis of iron sucrose-induced iron overload in pediatric patients.

Effect of different intravenous iron preparations on lymphocyte intracellular reactive oxygen species generation and subpopulation survival

BACKGROUND

Infections in hemodialysis (HD) patients lead to high morbidity and mortality rates and are associated with early cardiovascular mortality, possibly related to chronic inflammation. Intravenous (IV) iron is widely administered to HD patients and has been associated with increased oxidative stress and dysfunctional cellular immunity. The purpose of this study was to examine the effect of three commercially available IV iron preparations on intracellular reactive oxygen species generation and lymphocyte subpopulation survival.

METHODS

Peripheral blood mononuclear cells (PBMC) were isolated from healthy donor buffy coat. PBMC were cultured and incubated with 100 microg/mL of sodium ferric gluconate (SFG), iron sucrose (IS) or iron dextran (ID) for 24 hours. Cells were then probed for reactive oxygen species (ROS) with dichlorofluorescein-diacetate. In separate studies, isolated PBMCs were incubated with the 25, 50 or 100 microg/mL iron concentrations for 72 hours and then stained with fluorescein conjugated monoclonal antibodies for lymphocyte subpopulation identification. Untreated PBMCs at 24 hours and 72 hours served as controls for each experiment.

RESULTS

All three IV iron preparations induced time dependent increases in intracellular ROS with SFG and IS having a greater maximal effect than ID. The CD4+ lymphocytes were most affected by IV iron exposure, with statistically significant reduction in survival after incubation with all three doses (10, 25 and 100 microg/mL) of SFG, IS and ID.

CONCLUSION

These data indicate IV iron products induce differential deleterious effects on CD4+ and CD16+ human lymphocytes cell populations that may be mediated by intracellular reactive oxygen species generation. Further studies are warranted to determine the potential clinical relevance of these findings.

Effectiveness of oral iron to manage anemia in long-term hemodialysis patients with the use of ultrapure dialysate

The aim of this study was to evaluate the effectiveness of oral iron to manage anemia in long-term hemodialysis (HD) patients using ultrapure dialysate. This study was prospectively conducted on 23 patients (11 males and 12 females; median age 60 years, range 35-81) who underwent HD in our hospital from March to September 2007. The patients were randomly assigned to two treatment groups. The first group of 11 patients received ferrous fumarate 305 mg per oral tablet once a day, while the second group of 12 patients received infusions of 50 mg iron in a 0.9% sodium chloride solution. At the end of the 6-month treatment, patients receiving oral iron and intravenous iron had a significant increase in transferrin saturation from baseline (20.1±8.9 to 29.7±7.2; p=0.011 and 17.4±6.1 to 33.7±8.6; p=0.0001, respectively) and ferritin (32.6±15.4 to 115.4±28.2; p=0.0001 and 57.8±26.7 to 183.5±47.5; p=0.0002, respectively). In both groups, hemoglobin, hematocrit and dry weight were increased, but did not reach statistical significance. Moreover, both groups showed a significant reduction in the mean weekly erythropoietin dose from baseline (5,590.9±1,513.6 to 3,727.3±1,618.1; p=0.011 and 6,775.8±2,292.2 to 4,375.0±2,473.7; p=0.027, respectively). Oral iron is indeed as effective as intravenous iron in managing anemia in HD patients using ultrapure dialysate.

Comparison of the renal, cardiovascular and hepatic toxicity data of original intravenous iron compounds

BACKGROUND

Intravenous (i.v.) iron is essential for managing haemoglobin levels in haemodialysis patients. However, i.v. iron may cause variable degrees of toxicity. This is mainly related to the pharmacological characteristics of any given i.v. iron compound.

METHODS

This blinded study examines the effects of five i.v. iron preparations on haemodynamic and functional parameters. Sixty Sprague-Dawley rats (n = 10/group) received high or low molecular weight (HMW/LMW) iron dextran, ferric gluconate (FG), ferric carboxymaltose (FCM), iron sucrose (ISC) or isotonic saline solution (control). Five i.v. doses of iron (40 mg iron/kg) or saline were administered over 4 weeks.

RESULTS

Systolic blood pressure was significantly reduced in the LMW dextran group, whereas serum iron and percentage transferrin saturation were significantly elevated in all treatment groups. Creatinine clearance was reduced and urinary protein excretion increased in the FG group only (P < 0.01). Liver enzyme levels in the blood were increased (P < 0.01) in the FG and two dextran groups compared with the FCM and ISC groups. Analysis of liver, heart and kidney homogenates showed a significant increase in catalase and malondialdehyde levels in the FG group, and an increase in CuZn-superoxide dismutase and glutathione (GSH) peroxidase activity accompanied with a decrease in the reduced-to-oxidized GSH ratio in the FG and two dextran groups (P < 0.01). Tumour necrosis factor alpha and interleukin-6 levels were significantly elevated in liver, heart and kidney samples from the FG and two dextran groups but not the FCM, ISC or control groups.

CONCLUSIONS

These findings indicate that FG and HMW/LMW iron dextran have less favourable safety profiles than FCM and ISC in normal rats.

Inflammation and oxidative stress in end-stage renal disease patients treated with hemodialysis or peritoneal dialysis

PURPOSE

The impact of different dialysis modalities on oxidative stress and inflammation and the factors implicated in this interrelationship have not been adequately studied. This study was designed to comparatively evaluate the effect of hemodialysis (HD) and peritoneal dialysis (PD) on oxidative stress and inflammatory biomarkers and to search for associated factors.

METHODS

We studied 20 HD, 11 PD patients and 11 healthy controls. Calculations were based on total antioxidant capacity (TAC) and superoxide dismutase (SOD), by spectrophotometry, as oxidative stress biomarkers; and high sensitivity CRP (hs-CRP), Interleukin-6 (IL-6) and Tumor Necrosis Factor-alpha (TNF-alpha), by ELISA, as inflammation biomarkers.

RESULTS

HD and PD patients showed significantly increased levels of TA C, SOD and hs-CRP compared to healthy controls. No significant difference was observed in TNF-alpha and IL-6. Compared to HD patients, PD patients showed TNF-alpha levels that were increased, although non-significantly, and significantly higher homocysteine (Hcy). No differences were observed for IL-6, hs-CRP, TA C and SOD. In HD patients, significant positive correlations were found between intact parathyroid hormone (iPTH) and TNF-alpha, and between uric acid (UA) and TAC. Beta2-microglobulin (Beta2M) was negatively correlated with TAC, total cholesterol (TC) positively with TNF-alpha and negatively with SOD, and triglycerides (TG) correlated positively with TNF-alpha. In PD patients, TG correlated positively with TNF-alpha, HDL-cholesterol negatively with TNF-alpha, LDL-cholesterol negatively with SOD, and Beta2M negatively with SOD.

CONCLUSIONS

HD and PD patients show similar degrees of inflammation and oxidative stress activation. Factors such as UA, iPTH, Beta2M and lipid profile correlate to oxidative stress and inflammatory biomarkers in both HD and PD patients.

Evaluation of Oxidative Stress after Repeated Intravenous Iron Supplementation

Parenteral iron has been recommended for the treatment of iron deficiency in the majority of maintenance hemodialyzed (HD) patients. However, iron supplementation and consequent over saturation of transferrin and high iron levels, may aggravate oxidative stress already present in these patients. This study aimed to further clarify the role of repeated intravenous iron therapy as a supplementary cause of oxidative stress in HD patients. Markers of free radical activities (carbonyl reactive derivatives, CRD, thiol groups, SH, malondialdehyde, MDA) and antioxidant enzyme activities (superoxide dismutase, SOD and glutathione peroxidase, GPX) were determined in plasma and red blood cells (RBC) of 19 hemodialysis patients given a total iron dose of 625 mg (ferrogluconat, Ferrlecit, 62.5 mg). Blood samples were taken before the first and after the last dose of iron. Twenty apparently normal subjects served as healthy controls. Before iron treatment, HD patients exhibited increased concentrations of MDA and CRD in plasma and red blood cells, accompanied with impaired antioxidant capacity. All patients responded to iron therapy with a significant increase in their serum ferritin, serum iron, hemoglobin, and red blood cells levels. However, iron treatment resulted in enhanced oxidative stress in plasma of HD patients, since significant increase in plasma MDA and CRD concentrations, together with a decrease in nonprotein SH groups levels were detected. Supplementation with iron did not significantly influence plasma SOD and GPX activities, nor did any of the red blood cell parameters tested. Our data show that, despite improvement in hematological parameters, an increase in iron stores due to supplementation could also contribute to increased free radical production in HD patients.

Physicochemical properties of ferumoxytol, a new intravenous iron preparation

BACKGROUND

Intravenous iron is a critical component of anaemia management. However, currently available preparations have been associated with the release of free iron, a promoter of bacterial growth and oxidative stress.

MATERIALS AND METHODS

We determined the molecular weight, dialysability and capacity for free iron release of ferumoxytol, a semi-synthetic carbohydrate-coated superparamagnetic iron oxide nanoparticle. Ferumoxytol was compared with three intravenous iron preparations in clinical use: iron dextran (low molecular weight), sodium ferric gluconate and iron sucrose. Intravenous iron preparations were also incubated in rat, and pooled human sera (at concentrations of 600 microM and 42 microg mL(-1) respectively) from healthy subjects.

RESULTS

The molecular weight of ferumoxytol was 731 kDa. The relative order of molecular weight was as follows: ferumoxytol > iron dextran > iron sucrose > sodium ferric gluconate. The least ultrafilterable iron was observed with ferumoxytol and the most with ferric gluconate. The least dialysable free iron was observed with ferumoxytol and the most with ferric gluconate. Incubation of intravenous iron preparations in rat or pooled human sera demonstrated minimal free iron release with ferumoxytol. The order of catalytic iron release as detected by the bleomycin detectable iron assay was as follows: ferumoxytol < iron dextran < iron sucrose < ferric gluconate. A similar trend was observed for the in vivo serum concentration of free iron in rats.

CONCLUSIONS

In vitro observations from these experiments suggest that ferumoxytol has a favourable profile in terms of tendency to release free iron, in comparison with currently available intravenous iron preparations.

Safety issues with intravenous iron products in the management of anemia in chronic kidney disease

Anemia is a very common clinical problem in patients with chronic kidney disease (CKD) and is associated with increased morbidity and mortality in these patients. Erythropoietin is a hormone synthesized that is deficient in the majority of patients with advanced kidney disease, thereby predisposing these patients to anemia. The other cause of anemia is deficiency of iron. Iron deficiency anemia is common in people with CKD and its importance in supporting erythropoiesis is unquestioned, especially in those patients treated with erythropoietin. Intravenous iron is frequently used to treat anemia in CKD patients and is very efficacious in increasing hemoglobin but at the same time there are some safety issues associated with it. The objective of this review is to assess the frequency of adverse drug events associated with four different iron formulations: two iron dextran products known as high and low molecular weight iron dextran, iron sucrose, and sodium ferric gluconate complex. Several electronic databases were searched. In general, with the exception of high molecular weight iron dextran, serious or life-threatening adverse events appeared rare. Iron sucrose has the least reported adverse events and high molecular weight iron dextran has the highest number of reported adverse events. Low molecular weight iron dextran and ferric gluconate fall in between these two for number of adverse drug events.