Renal clearable nanochelators for iron overload therapy.

Iron chelators have been widely used to remove excess toxic iron from patients with secondary iron overload. However, small molecule-based iron chelators can cause adverse side effects such as infection, gastrointestinal bleeding, kidney failure, and liver fibrosis. Here we report renal clearable nanochelators for iron overload disorders. First, after a singledose intravenous injection, the nanochelator shows favorable pharmacokinetic properties, such as kidney-specific biodistribution and rapid renal excretion (>80% injected dose in 4 h), compared to native deferoxamine (DFO). Second, subcutaneous (SC) administration of nanochelators improves pharmacodynamics, as evidenced by a 7-fold increase in efficiency of urinary iron excretion compared to intravenous injection. Third, daily SC injections of the nanochelator for 5 days to iron overload mice and rats decrease iron levels in serum and liver. Furthermore, the nanochelator significantly reduces kidney damage caused by iron overload without demonstrating DFO's own nephrotoxicity. This renal clearable nanochelator provides enhanced efficacy and safety.

Biocompatibility and toxicity of novel iron chelator Starch-Deferoxamine (S-DFO) compared to zinc oxide nanoparticles to zebrafish embryo: An oxidative stress based apoptosis, physicochemical and neurological study profile.

OBJECTIVES: Clinically approved iron chelators are effective in decreasing significant transfusional iron accumulation. Starch-Deferoxamine (S-DFO), a novel high molecular weight iron chelator, was produced to increase binding capacity to iron and reduce toxicity. Although its efficacy was established in one small cohort clinical trial, its potential adverse effect was not adequately addressed. METHODS: We utilized zebrafish model to assess S-DFO toxicity using following assays: mortality, teratogenicity, hatching rate, tail flicking, Acridine Orange staining for apoptosis detection, o-dianisidine staining for hemoglobin synthesis, and the level of Hsp70 as a general stress indicator. Embryos were exposed to different concentrations of S-DFO, Zinc Oxide nanoparticle (ZnO) (positive control), along with untreated control (UC). RESULTS: S-DFO showed no significant mortality nor deformities at all tested concentrations (0.0-1000 µM). Thus, the LC50 is expected to >1000 µM. 100 µM S-DFO treatment did not affect embryo development (as judged by hatching rate); neuromuscular activity (as judged by tail flicking); and hemoglobin synthesis. Neither apoptosis, nor increase in Hsp70 level was noticed upon S-DFO treatment. CONCLUSION: Our assays demonstrate that S-DFO does not induce cellular or biochemical stress and has no adverse effect on organ development of zebrafish embryos, suggesting its safe use as an iron chelator.

SF-deferoxamine, a bone-seeking angiogenic drug, prevents bone loss in estrogen-deficient mice.

Deferoxamine (DFO) possesses a good chelating capability and is therefore used for the clinical treatment of ion deposition diseases. Increasing evidence shows that DFO can inhibit the activity of proline hydroxylase (PHD) by chelating iron, resulting in hypoxia-induced factor (HIF) signaling activation and angiogenesis promotion. However, clinical evidence indicates that a high concentration of DFO could be biotoxic due to its enrichment in related organs. Thus, we established a new compound by conjugating DFO with the bone-seeking agent iminodiacetic acid (IDA); the new agent is called SF-DFO, and we verified its promotion of HIF activation and tube formation in vivo. After confirming the bone-seeking property of SF-DFO in the femur and vertebra of both male and female mice and comparing it to that of DFO, we analyzed the protective effect of DFO and SF-DFO in an ovariectomized (OVX) mouse model. The serum CTX-I level revealed no influence of DFO and SF-DFO on osteoclast activity, but the blood vessels and osteoblasts in the metaphysis were more abundant after SF-DFO treatment, which resulted in a greater protective effect against trabecular bone loss compared to the DFO group. Additionally, the cortical parameters and bone strength performance were identical between the DFO and SF-DFO groups. However, the diffuse inflammatory response in the liver and spleen that occurred after DFO injection was not observed in the SF-DFO group. Thus, with reduced biotoxicity and an equivalent bone-seeking capability, SF-DFO may be a better choice for the prevention of vascular degradation-induced osteoporosis.

Deferoxamine-induced electronegative ERG responses.

PURPOSE: To report a case of deferoxamine-induced retinopathy characterized by electroretinography (ERG), optical coherence tomography angiography (OCT-A), and other multimodal imaging. METHODS: This is an observational case report of one patient. Full-field ERG was performed. OCT-A, spectral-domain optical coherence tomography (SD-OCT), color fundus photography, and fundus autofluorescence were used to characterize the retinopathy induced by deferoxamine use. RESULTS: A 64-year-old man with a history of ß-thalassemia intermedia presented with worsening visual acuity, nyctalopia, and electronegative ERG. OCT-A revealed atrophy of the choriocapillaris in areas of hypoautofluorescence, corresponding to regions of retinal atrophy. SD-OCT showed disruption of the ellipsoid zone, granular hyperreflective deposits within the retinal pigment epithelium, thinning of the retinal layers, and extensive choroidal sclerosis and atrophy of the retinal pigment epithelium. CONCLUSION: Deferoxamine-induced retinopathy can manifest with electronegative maximal ERG responses, and OCT-A can be used to detect deferoxamine toxicity.

Inhibition of P-glycoprotein stimulates cell death under Hypoxia-mimicking conditions.

The most common drug resistance mechanism in tumor cells is expression on their surface of the energy-dependent pump like P-glycoprotein (P-gp) that expels chemotherapeutic agents from the interior. An imitation of the hypoxic condition by the iron chelator deferoxamine caused Hypoxia-inducible factor 1-alpha (HIF-1α) stabilization and inhibition of doxorubicin-induced apoptosis in colon cancer НСТ116 cells. P-gp blocker verapamil suppressed doxorubicin accumulation leading to cell death induction. Considering these results, P-gp may be used as a potential target to stimulate chemotherapeutic drugs activity that will contribute to more efficient tumor cells elimination.

In vivo efficacy, toxicity and biodistribution of ultra-long circulating desferrioxamine based polymeric iron chelator.

Desferrioxamine (DFO) is currently in clinical use to remove iron from transfusion-dependent patients with ß-thalassemia major, sickle-cell anemia and the myelodysplastic syndromes. However, its short half-life, burdensome, subcutaneous mode of administration and propensity to cause neurotoxicity at high doses greatly hinder its use. Thus, developing an optimized version of DFO with extended half-life, and reduced toxicity is a major goal. Using high molecular weight (MW), non-toxic, hyperbranched polyglycerol with high functionality, we demonstrate that the efficacy of DFO can be tuned with considerable reduction in toxicity. Using zebrafish embryos and mice, we tested toxicity, iron removal efficacy with low dosing and the biodistribution of ultra-long circulating DFO (ULC-DFO) conjugates. There was no significant difference in the mortality and development of zebrafish embryos upon exposure to ULC-DFO. Similarly, body weights and serum lactate dehydrogenase levels in mice treated with ULC-DFO remained within the normal range throughout the tolerance study. Moreover, ULC-DFO is significantly more effective than low MW DFO in promoting iron removal both from organs and via urine in iron overloaded mice despite using a moderate, once-weekly dosing schedule. This is probably due to the extended circulation half-life of ULC-DFO. The MW of ULC-DFO influences the accumulation and biodistribution, with highest MW (637 KDa) associated with up to 12% accumulation in the liver. In contrast, ULC-DFO with MWs of 75 KDa and lower were associated with relatively low organ accumulation, indicating that biodistribution of ULC-DFO can be tuned. Since ULC-DFO has improved iron removal properties, longer plasma retention time and possesses excellent biocompatibility, it represents a polymer conjugate with high clinical utility in comparison to DFO for the treatment of transfusion dependent iron overload. More importantly, ULC-DFO is anticipated to reduce the requirement for prolonged subcutaneous infusion of DFO.

Synthesis and evaluation of oxidation-responsive alginate-deferoxamine conjugates with increased stability and low toxicity.

Deferoxamine is commonly used for iron-overload related diseases, its drawbacks such as instability and toxicity, however, significantly limited its utility in clinic. To address these issues, oxidation-responsive alginate-deferoxamine (Alg-DFO) conjugates were synthesized and their structure was characterized. The metabolism studies shown the conjugation of alginate significantly increased the stability of the DFO, with half-life more than 10 times longer than that of the free DFO. Moreover, the conjugates could not only quickly respond to oxidative stimuli and degradation, suggesting their potential to be cleared from the body by responding to iron-overload associated oxidative environment to avoid its accumulation and safety concern, but also protect iron binding capacity of the attached DFO from oxidation. The degradation mechanism for oxidative-response was proposed. In addition, the conjugates shown lower cytotoxicity compared to the free DFO. Taken together, the Alg-DFO conjugates synthesized in this work has promise for treating iron-overload related conditions.

Deferoxamine promotes MDA-MB-231 cell migration and invasion through increased ROS-dependent HIF-1α accumulation.

BACKGROUND/AIM: Deferoxamine (DFO), an iron chelator, has been reported to induce hypoxia-inducible factor-1α (HIF-1α) expression. HIF-1α plays a critical role in promoting tumor metastasis. However, the molecular mechanisms underlying induction of HIF-1α in breast cancer cells remain unknown. Our aim was to ascertain whether DFO enhanced cancer metastasis in MDA-MB-231 cells. METHODS: Cellular reactive oxygen species (ROS) was measured by flow cytometry. Cell migration was determined by wound healing and transwell assays. Protein and mRNA expression were detected by western blotting and RT-PCR, respectively. RESULTS: DFO treatment enhanced cell migration and invasion, while HIF-1α expression was significantly up-regulated at the post-transcriptional level. However, treatment with a NADPH oxidase inhibitor, diphenyleneiodonium (DPI), strongly inhibited ROS generation and HIF-1α expression, as well as cell migration and invasion. Notably, DFO treatment increased extracellular signal-regulated kinase (ERK)1/2 phosphorylation. Inhibition of ROS production with DPI attenuated DFO-induced ERK1/2 activation. Moreover, a MEK1 inhibitor, PD98059, suppressed DFO-induced cell migration and invasion. CONCLUSION: DFO-induced HIF-1α expression involves a cascade of signaling events including ROS generation, activation of ERK signaling, and subsequent promotion of cell migration and invasion. These findings indicate a risk associated with DFO and other iron chelators for treatment of tumors with invasive potential.

Adipokine expression in brown and white adipocytes in response to hypoxia.

BACKGROUND: Adipose tissue has emerged as an important endocrine regulator by secreting hormones referred to as adipokines. Recent studies showed that adipose tissue considerably responds to hypoxia. Although the impact of white adipose tissue on regulative processes is established, the importance of brown adipose tissue in adults has emerged just recently. METHODS: Brown (BA) and white adipocytes (WA) were cultured either in the presence of chemical hypoxia-mimetics or under hypoxic atmosphere of 1% oxygen. Expression of hypoxia-inducible factor 1α (HIF- 1α) was assessed by western blot. The expression levels of several known HIF-1α-regulated proteins [vascular endothelial growth factor (VEGF), leptin, adiponectin, and angiotensinogen (AGT)] were quantified. RESULTS: Both chemical hypoxia-mimetics and physical hypoxia led to increased nuclear HIF-1α expression and to decreased cytoplasmatic adiponectin in both cell types. In contrast, VEGF and AGT expression did not change upon hypoxic stimulation. Leptin was exclusively detectable in WA, while uncoupling-protein 1 (UCP-1) was expressed in BA only. CONCLUSIONS: WA and BA are sensitive to hypoxia, in which HIF-1α expression is induced. Protein expression of adiponectin is hypoxia-dependent, whereas AGT, VEGF, leptin, and UCP-1 expression do not change secondary to hypoxia.

The antibacterial activity of Ga3+ is influenced by ligand complexation as well as the bacterial carbon source.

Gallium ions have previously been shown to exhibit antibacterial and antibiofilm properties. In this study, we report differential bactericidal activities of two gallium complexes, gallium desferrioxamine B (Ga-DFOB) and gallium citrate (Ga-Cit). Modeling of gallium speciation in growth medium showed that DFOB and citrate both can prevent precipitation of Ga(OH)(3), but some precipitation can occur above pH 7 with citrate. Despite this, Ga-Cit 90% inhibitory concentrations (IC(90)) were lower than those of Ga-DFOB for clinical isolates of Pseudomonas aeruginosa and several reference strains of other bacterial species. Treatment with Ga compounds mitigated damage inflicted on murine J774 macrophage-like cells infected with P. aeruginosa PAO1. Again, Ga-Cit showed more potent mitigation than did Ga-DFOB. Ga was also taken up more efficiently by P. aeruginosa in the form of Ga-Cit than in the form of Ga-DFOB. Neither Ga-Cit nor Ga-DFOB was toxic to several human cell lines tested, and no proinflammatory activity was detected in human lung epithelial cells after exposure in vitro. Metabolomic analysis was used to delineate the effects of Ga-Cit on the bacterial cell. Exposure to Ga resulted in lower concentrations of glutamate, a key metabolite for P. aeruginosa, and of many amino acids, indicating that Ga affects various biosynthesis pathways. An altered protein expression profile in the presence of Ga-Cit suggested that some compensatory mechanisms were activated in the bacterium. Furthermore, the antibacterial effect of Ga was shown to vary depending on the carbon source, which has importance in the context of medical applications of gallium.

Differentiating the growing nosocomial infectious threats Ralstonia pickettii and Ralstonia insidiosa.

Differentiation of the growing nosocomial infectious threats, Ralstonia pickettii and Ralstonia insidiosa, based on nitrate reduction, desferrioxamine susceptibility, arabinose, N-acetyl-glucosamine and phenylacetate assimilation is described. These tests can be used for preliminary identification of Ralstonia pickettii and Ralstonia insidiosa resulting in more accurate identification of these species.

Leishmania chagasi: effect of the iron deficiency on the infection in BALB/c mice.

Iron deficiency and visceral leishmaniasis are serious problems of public health. The aim of this study was to evaluate the effect of iron deficiency, induced by the iron chelator desferrioxamine, on the course of the infection by Leishmania chagasi in BALB/c mice. Our data show that the iron chelator caused significant reduction in hemoglobin concentration of treated mice and reduction in parasite load in spleen and liver. Significant differences were not observed in the production of IFN-gamma and IL-4 among the experimental groups. In conclusion, the data reported in this paper suggest that iron deficiency may favor the host. If there is not enough iron available to the parasite, its multiplication may be reduced and infection attenuated.

Deferoxamine mesylate is toxic for retinal pigment epithelium cells in vitro, and its toxicity is mediated by p38.

Deferoxamine mesylate is clinically used as a chelating agent but might induce retinopathy. To evaluate its effect on the retinal pigment epithelium (RPE), porcine RPE cells were stimulated with deferoxamine. Cell death was assessed with trypan blue exclusion assay. To investigate the pathway of cell death, the mitogen-activated protein kinases (MAPKs) Erk, JNK, and p38 were inhibited with U0126, SP600125, and SB203580, respectively. Their activity was determined by Western blot. Deferoxamine induces significant cell death in RPE cells, accompanied by phosphorylation of p38 and Erk. Inhibition of p38 attenuates cell death. In conclusion, deferoxamine is directly toxic on RPE cells, its toxicity depending on p38.

Deferoxamine mimics the pattern of hypoxia-related injury at the microvasculature.

Oxygen is essential for the maintenance of life, and when oxygen levels decline to critical levels, a program of complex mechanisms exists to i) sense hypoxia, ii) respond to minimize acute tissue injury, and iii) result in adaptations that offer protection against further hypoxia challenges. Alternative adaptation-related protection may also be inducible through the increased activity of hypoxia-inducible factors activated by hypoxia mimics such as iron chelation with deferoxamine (DFA). We have characterized a set of hypoxia-related responses at the microvasculature and postulated that microvascular injury in response to hypoxia could be reproduced by the reduction of bioavailable iron through chelation by DFA. We were able to induce a similar degree of leukocyte adherence and emigration and vascular leak with DFA infusion as compared with hypoxia exposure in an intact physiological rodent model. However, in contrast to hypoxia-exposed groups, we were unable to detect reactive oxygen species or alter the injury pattern with reactive oxygen species scavenger in the groups treated with DFA. Thus, we demonstrate that DFA mimics the pattern and intensity of hypoxia-related injury on the microvasculature; however, differences in the time course and mechanism of injury were identified. In addition, DFA saturated with iron did not completely reverse the effects of DFA, suggesting a mechanism(s) beyond a reduction in the bioavailability of iron. These findings may have importance in the targeting of iron for the development of hypoxia mimics that may offer protection against subsequent hypoxia exposure in clinical setting such as myocardial infarction and stroke.

The effect of an iron (III) chelator, silybin, on the proliferation and cell cycle of Jurkat cells: a comparison with desferrioxamine.

Silybin is a flavonoid with antioxidant and free radical scavenging abilities. Silybin also acts as an iron chelator by binding Fe (III). The present study was undertaken to assess the biological effects of silybin on T leukemia cells in the presence or absence of iron and compare its effects with a well-known iron chelator; desferrioxamine. In these experiments, we studied the growth capacity of Jurkat while varying iron availability in the environment. Desferrioxamine significantly inhibited growth and proliferation of Jurkat cells, blocking treated cells in the G0/G1 phase and inducing apoptosis. In contrast, silybin showed a bimodal effect, inducing cell proliferation at lower concentrations whereas inhibition of DNA synthesis and significant cell death was observed at higher concentrations. Chelation of Fe totally abrogated antiproliferative, cytotoxic and apoptotic effects of desferrioxamine on Jurkat cells. Conversely, the silybin-Fe complex had no appreciable effect on its antiproliferative and cytotoxic activities. The cytotoxic effect of desferrioxamine was also prevented in iron-loaded Jurkat cells; however, the effect of silybin on the growth and viability of iron-loaded cells was similar to the effect of its iron complex on untreated Jurkat cells. Despite the Fe chelating activity of silybin that suggests its possible application in chelation therapy of chronic iron overload, the biological effects of silybin on Jurkat cells are different than those of desferrioxamine, probably due to antioxidant activity of silybin, which causes pro-oxidant effect via iron-catalyzed oxidation with the subsequent generation of reactive oxygen species.

Intoxicació accidental per ferro a l’edat pediàtrica. Revisió d’un cas / No disponible

Introducció. La ingesta accidental de ferro representauna de les primeres causes de mort per intoxicació en infants menors de 6 anys en països com els Estats Units, amb una taxa de mortalitat entre els casos d'intoxicació greu superior al 10%, i una incidència mitjana de 3.000 casos l'any en el període comprès entre 1986 i 1997, any en què la US Food and Drug Administration (FDA) va publicar noves normes d'empaquetament monodosi per a aquests productes. Tot i així, és una intoxicació poc freqüent al nostre medi, cosa que fa important aprofundir en el coneixement d'aquesta intoxicació potencialment letal per assegurar un maneig correcte que permeti reduir-ne la morbimortalitat.Observació clínica. Presentem el cas d'una nena de 21mesos amb sospita d'intoxicació aguda per ferro, desprésd'ingerir 73 comprimits d'una presentació de parafarmàcia(dosi tòxica ingerida de ferro element: 21 mg/kg). Es va fer un rentat gàstric, i la pacient es va mantenir asimptomàtica durant les 12 hores d'observació.Comentaris. Només els valors de siderèmia obtingutsentre les quatre i sis hores postingesta es correlacionenamb el grau de toxicitat. En absència de valors de siderèmia és necessari calcular la dosi tòxica ingerida per kg de pes, per valorar la gravetat de la intoxicació i iniciar mesures destinades a evitar l'absorció del ferro: rentat gàstric, irrigació intestinal i tractament quelant amb deferoxamina. És important evitar l'alta precoç d'aquests pacients, ja que la toxicitat sistèmica no apareix fins les 12-24 hores postingesta

No disponible

Autophagy after experimental intracerebral hemorrhage.

Autophagy contributes to ischemic brain injury, but it is not clear if autophagy occurs after intracerebral hemorrhage (ICH). This study examined whether ICH-induced cell death is partly autophagic. It then examined the role of iron in inducing this form of cell death after ICH. Male, adult Sprague-Dawley rats received an infusion of autologous whole blood or ferrous iron into the right basal ganglia. Control rats (sham) had a needle insertion. The rats were killed at 1, 3, 7, or 28 days later. Some rats were treated with either deferoxamine or vehicle after ICH. Microtubule-associated protein light chain-3 (LC3), a biomarker of autophagosome, and cathepsin D, a lysosomal biomarker, were measured by Western blot analysis and immunohistochemistry. Immunofluorescent double-labeling was used to identify the cell types expressing cathepsin D. Electron microscopy was performed to examine the cellular ultrastructure changes after ICH. We found that conversion of LC3-I to LC3-II, cathepsin D expression, and vacuole formation are increased in the ipsilateral basal ganglia after ICH. Intracerebral infusion of iron also resulted in enhanced conversion of LC3-I to LC3-II and increased cathepsin D levels. Deferoxamine (an iron chelator) treatment significantly reduced the conversion of LC3-I to LC3-II and cathepsin D levels after ICH. Our results demonstrated that autophagy occurs after ICH, and iron has a key role in ICH-induced autophagy. This also suggests that iron-induced autophagy may play a role in brain injury in other diseases associated with iron overload.

Inhibitory effect of 6-formylpterin on HIF-1alpha protein accumulation.

Hypoxia-inducible factor-1 (HIF-1) is a main regulator of metabolic adaptation to hypoxia. HIF-1alpha is induced by hypoxia, or by hypoxia-mimicking reagents, such as desferrioxamine (DFX), under a normoxic condition. A xanthine oxidase inhibitor, 6-formylpterin (6FP), is reported to exert its functions on reactive oxygen species (ROS) modulation. In this study, we investigated the effect of 6FP on HIF-1alpha expression under a DFX-treated or hypoxic condition. 6FP decreased HIF-1alpha expression at the protein level, but not at the mRNA level, in a dose-dependent manner, and this suppressive effect was reversed by the antioxidant, N-acetyl-L-cysteine (NAC). Furthermore, the ROS generated by 6FP was reversed with NAC coincubation. These findings suggest that intracellular ROS generated by 6FP decreased the HIF-1alpha protein accumulation under a DFX-treated or hypoxic condition.

[Retinal pigment epithelium--desferal]. / Rétine et epithélium pigmentaire--le desferal.

Deferoxamine mesylate (Desferal) is a chelating agent used in hemosiderosis and aluminium overload consecutive to renal dialysis. This drug is the most efficacious for treating iron overload but is associated with ocular toxicity: dose and duration related symptomatic optic neuropathy on the one hand, reversible if treatment stopped, and acute retinal involvement followed by irreversible paucisymptomatic pigmentary changes on the other hand. Toxic risk factors are intravenous mode of administration, high doses, small iron or aluminium overload, diabetes and young age. Hence, dosis should be adapted to the amount of overload and ophthalmological follow-up should be instaured. Indeed, if treatment is stopped at the beginning of the toxic effect, ocular involvement is reversible. The baseline ophthalmological examination should include visual acuity measurement, color vision, visual fields, slit lamp and fundus. In case of risk factors, electrophysiology and fluoangiography should be added.

Wear particles generated from studded tires and pavement induces inflammatory reactions in mouse macrophage cells.

Health risks associated with exposure to airborne particulate matter (PM) have been shown epidemiologically as well as experimentally, pointing to both respiratory and cardiovascular effects. These health risks are of increasing concern in society, and to protect public health, a clarification of the toxic properties of particles from different sources is of importance. Lately, wear particles generated from traffic have been recognized as a major contributing source to the overall particle load, especially in the Nordic countries where studded tires are used. The aim of this study was to further investigate and compare the ability to induce inflammatory mediators of different traffic-related wear particles collected from an urban street, a subway station, and studded tire-pavement wear. Inflammatory effects were measured as induction of nitric oxide (NO), IL-6, TNF-alpha, arachidonic acid (AA), and lipid peroxidation after exposure of the murine macrophage like cell line RAW 264.7. In addition, the redox potential of the particles was measured in a cell-free system. The results show that all particles tested induce IL-6, TNF-alpha, and NO, and those from the urban street were the most potent ones. In contrast, particles collected from a subway station were most potent to induce lipid peroxidation, AA release, and formation of ROS. Particles from studded tire-pavement wear, generated using a road simulator, were able to induce inflammatory cytokines, NO, lipid peroxidation, and ROS formation. Interestingly, particles generated from pavement containing granite as the main stone material were more potent than those generated from pavement containing quartzite as the main stone material.