The Importance and Essentiality of Natural and Synthetic Chelators in Medicine: Increased Prospects for the Effective Treatment of Iron Overload and Iron Deficiency.

The supply and control of iron is essential for all cells and vital for many physiological processes. All functions and activities of iron are expressed in conjunction with iron-binding molecules. For example, natural chelators such as transferrin and chelator-iron complexes such as haem play major roles in iron metabolism and human physiology. Similarly, the mainstay treatments of the most common diseases of iron metabolism, namely iron deficiency anaemia and iron overload, involve many iron-chelator complexes and the iron-chelating drugs deferiprone (L1), deferoxamine (DF) and deferasirox. Endogenous chelators such as citric acid and glutathione and exogenous chelators such as ascorbic acid also play important roles in iron metabolism and iron homeostasis. Recent advances in the treatment of iron deficiency anaemia with effective iron complexes such as the ferric iron tri-maltol complex (feraccru or accrufer) and the effective treatment of transfusional iron overload using L1 and L1/DF combinations have decreased associated mortality and morbidity and also improved the quality of life of millions of patients. Many other chelating drugs such as ciclopirox, dexrazoxane and EDTA are used daily by millions of patients in other diseases. Similarly, many other drugs or their metabolites with iron-chelation capacity such as hydroxyurea, tetracyclines, anthracyclines and aspirin, as well as dietary molecules such as gallic acid, caffeic acid, quercetin, ellagic acid, maltol and many other phytochelators, are known to interact with iron and affect iron metabolism and related diseases. Different interactions are also observed in the presence of essential, xenobiotic, diagnostic and theranostic metal ions competing with iron. Clinical trials using L1 in Parkinson's, Alzheimer's and other neurodegenerative diseases, as well as HIV and other infections, cancer, diabetic nephropathy and anaemia of inflammation, highlight the importance of chelation therapy in many other clinical conditions. The proposed use of iron chelators for modulating ferroptosis signifies a new era in the design of new therapeutic chelation strategies in many other diseases. The introduction of artificial intelligence guidance for optimal chelation therapeutic outcomes in personalised medicine is expected to increase further the impact of chelation in medicine, as well as the survival and quality of life of millions of patients with iron metabolic disorders and also other diseases.

Qualitative and Quantitative Analysis of Siderophore Production from Pseudomonas aeruginosa.

Pseudomonas aeruginosa (P. aeruginosa) is known for its production of a diverse range of virulence factors to establish infections in the host. One such mechanism is the scavenging of iron through siderophore production. P. aeruginosa produces two different siderophores: pyochelin, which has lower iron-chelating affinity, and pyoverdine, which has higher iron-chelating affinity. This report demonstrates that pyoverdine can be directly quantified from bacterial supernatants, while pyochelin needs to be extracted from supernatants before quantification. The primary method for qualitatively analyzing siderophore production is the Chrome Azurol Sulfonate (CAS) agar plate assay. In this assay, the release of CAS dye from the Fe3+-Dye complex leads to a color change from blue to orange, indicating siderophore production. For the quantification of total siderophores, bacterial supernatants were mixed in equal proportions with CAS dye in a microtiter plate, followed by spectrophotometric analysis at 630 nm. Pyoverdine was directly quantified from the bacterial supernatant by mixing it in equal proportions with 50 mM Tris-HCl, followed by spectrophotometric analysis. A peak at 380 nm confirmed the presence of pyoverdine. As for Pyochelin, direct quantification from the bacterial supernatant was not possible, so it had to be extracted first. Subsequent spectrophotometric analysis revealed the presence of pyochelin, with a peak at 313 nm.

Growth and endocrinopathies among children with ß-Thalassemia major treated at Dubai Thalassemia centre.

BACKGROUND: ß-Thalassemia major (BTM) is one of the most common hereditary anemias worldwide. Patients suffer from iron overload that results from repeated blood transfusion This in turn leads to multiple organ damage and endocrinopathies. This study aims to assess the prevalence of growth retardation, hypothyroidism, and diabetes mellitus in children and adolescents with BTM treated at Dubai Thalassemia Centre. METHODS: A total of 105 children and adolescents were included in this retrospective observational study. RESULTS: 39 children and 66 adolescents' data were analyzed. Females composed 51.3% (n = 20) of children and 53.0% (n = 35) of adolescents. Pretransfusion hemoglobin below 9 gm/dl was observed in 10.8% (n = 4) and 10.6% (n = 7) in children and adolescents, respectively. The mean age of menarche was 13.5 years. Among all study participants, 22.6% (n = 14) had normal height velocity whereas 37.1% (n = 23) had reduced height velocity in one year and 40.3% (n = 25) had reduced height velocity in two consecutive years. The proportion of children and adolescents showing reduced height velocity was significantly higher in females compared to the males (90.6% versus 63.3%, respectively, Chi-square = 6.597, p-value = 0.010). Although none of the study participants had diabetes mellitus, 26.1% (n = 12/46) had pre-diabetes. Elevated TSH was observed in 14.7% (n = 5) children and 8.1% (n = 5) adolescents while low FT4 was reported in one child and one adolescent. CONCLUSION: Of all endocrinopathies seen among children and adolescents with BTM, growth delay remains the main concern for this group of patients. Effective treatment is key to further reducing endocrinopathies. Although the sample size is limited, we postulate that the low percentage of endocrinopathies among children with BTM treated at Dubai thalassemia center and the low level of pretransfusion anemia reflect the effective transfusion and chelation at the center.

Both hemoglobin and hemin cause damage to retinal pigment epithelium through the iron ion accumulation.

Subretinal hemorrhages result in poor vision and visual field defects. During hemorrhage, several potentially toxic substances are released from iron-based hemoglobin and hemin, inducing cellular damage, the detailed mechanisms of which remain unknown. We examined the effects of excess intracellular iron on retinal pigment epithelial (RPE) cells. A Fe2+ probe, SiRhoNox-1 was used to investigate Fe2+ accumulation after treatment with hemoglobin or hemin in the human RPE cell line ARPE-19. We also evaluated the production of reactive oxygen species (ROS) and lipid peroxidation. Furthermore, the protective effect of-an iron chelator, 2,2'-bipyridyl (BP), and ferrostatin-1 (Fer-1) on the cell damage, was evaluated. Fe2+ accumulation increased in the hemoglobin- or hemin-treated groups, as well as intracellular ROS production and lipid peroxidation. In contrast, BP treatment suppressed RPE cell death, ROS production, and lipid peroxidation. Pretreatment with Fer-1 ameliorated cell death in a concentration-dependent manner and suppressed ROS production and lipid peroxidation. Taken together, these findings indicate that hemoglobin and hemin, as well as subretinal hemorrhage, may induce RPE cell damage and visual dysfunction via intracellular iron accumulation.

MALDI-mass spectrometry imaging as a new technique for detecting non-heme iron in peripheral tissues via caudal vein injection of deferoxamine.

As one of the most common iron-chelating agents, deferoxamine (DFO) rapidly chelates iron in the body. Moreover, it does not compete for the iron characteristic of hemoglobin in the blood cells, which is common in the clinical treatment of iron poisoning. Iron is a trace element necessary to maintain organism normal life activities. Iron deficiency can lead to anemia, whereas iron overload can cause elevated levels of cellular oxidative stress and cell damage. As a consequence, detection of the iron content in tissues and blood is of great significance. The traditional techniques for detecting the iron content include inductively coupled plasma-mass spectrometry and atomic absorption spectrometry, which cannot be used for imaging purposes. Laser ablation-ICP-MS and synchrotron radiation micro-X-ray fluorescence can map the concentration and distribution of iron in tissues. However, these methods can only be used to measure the total iron levels in blood or tissues. In recent years, due to the deepening understanding of iron metabolism, diseases related to iron overload have attracted increasing attention. Therefore, we took advantage of the properties of DFO in terms of chelating iron and investigated different sampling times following DFO injection in the tail vein of mice. We used mass spectrometry imaging (MSI) technology to detect the DFO and ferrioxamine content in the blood and different tissues to indirectly characterize the non-heme iron content.

Research advances on molecular mechanism and natural product therapy of iron metabolism in heart failure.

The progression of heart failure (HF) is complex and involves multiple regulatory pathways. Iron ions play a crucial supportive role as a cofactor for important proteins such as hemoglobin, myoglobin, oxidative respiratory chain, and DNA synthetase, in the myocardial energy metabolism process. In recent years, numerous studies have shown that HF is associated with iron dysmetabolism, and deficiencies in iron and overload of iron can both lead to the development of various myocarditis diseases, which ultimately progress to HF. Iron toxicity and iron metabolism may be key targets for the diagnosis, treatment, and prevention of HF. Some iron chelators (such as desferrioxamine), antioxidants (such as ascorbate), Fer-1, and molecules that regulate iron levels (such as lactoferrin) have been shown to be effective in treating HF and protecting the myocardium in multiple studies. Additionally, certain natural compounds can play a significant role by mediating the imbalance of iron-related signaling pathways and expression levels. Therefore, this review not only summarizes the basic processes of iron metabolism in the body and the mechanisms by which they play a role in HF, with the aim of providing new clues and considerations for the treatment of HF, but also summarizes recent studies on natural chemical components that involve ferroptosis and its role in HF pathology, as well as the mechanisms by which naturally occurring products regulate ferroptosis in HF, with the aim of providing reference information for the development of new ferroptosis inhibitors and lead compounds for the treatment of HF in the future.

The Irony of Iron: The Element with Diverse Influence on Neurodegenerative Diseases.

Iron accumulation in the brain is a common feature of many neurodegenerative diseases. Its involvement spans across the main proteinopathies involving tau, amyloid-beta, alpha-synuclein, and TDP-43. Accumulating evidence supports the contribution of iron in disease pathologies, but the delineation of its pathogenic role is yet challenged by the complex involvement of iron in multiple neurotoxicity mechanisms and evidence supporting a reciprocal influence between accumulation of iron and protein pathology. Here, we review the major proteinopathy-specific observations supporting four distinct hypotheses: (1) iron deposition is a consequence of protein pathology; (2) iron promotes protein pathology; (3) iron protects from or hinders protein pathology; and (4) deposition of iron and protein pathology contribute parallelly to pathogenesis. Iron is an essential element for physiological brain function, requiring a fine balance of its levels. Understanding of disease-related iron accumulation at a more intricate and systemic level is critical for advancements in iron chelation therapies.

Deferasirox exerts anti-epileptic effects by improving brain iron homeostasis via regulation of ITPRIP.

Epilepsy constitutes a global health concern, affecting millions of individuals and approximately one-third of patients exhibit drug resistance. Recent investigations have revealed alterations in cerebral iron content in both epilepsy patients and animal models. However, the extant literature lacks a comprehensive exploration into the ramifications of modulating iron homeostasis as an intervention in epilepsy. This study investigated the impact of deferasirox, a iron ion chelator, on epilepsy. This study unequivocally substantiated the antiepileptic efficacy of deferasirox in a kainic acid-induced epilepsy model. Furthermore, deferasirox administration mitigated seizure susceptibility in a pentylenetetrazol-induced kindling model. Conversely, the augmentation of iron levels through supplementation has emerged as a potential exacerbating factor in the precipitating onset of epilepsy. Intriguingly, our investigation revealed a hitherto unreported discovery: ITPRIP was identified as a pivotal modulator of excitatory synaptic transmission, regulating seizures in response to deferasirox treatment. In summary, our findings indicate that deferasirox exerts its antiepileptic effects through the precise targeting of ITPRIP and amelioration of cerebral iron homeostasis, suggesting that deferasirox is a promising and novel therapeutic avenue for interventions in epilepsy.

Integration of metalloproteome and immunoproteome reveals a tight link of iron-related proteins with COVID-19 pathogenesis and immunity.

Increasing clinical data show that the imbalance of host metallome is closely associated with different kinds of disease, however, the intrinsic mechanisms of action of metals in immunity and pathogenesis of disease remain largely undefined. There is lack of multiplexed profiling system to integrate the metalloproteome-immunoproteome information at systemic level for exploring the roles of metals in immunity and disease pathogenesis. In this study, we build up a metal-coding assisted multiplexed proteome assay platform for serum metalloproteomic and immunoproteomic profiling. By taking COVID-19 as a showcase, we unbiasedly uncovered the most evident modulation of iron-related proteins, i.e., Ft and Tf, in serum of severe COVID-19 patients, and the value of Ft/Tf could work as a robust biomarker for COVID-19 severity stratification, which overtakes the well-established clinical risk factors (cytokines). We further uncovered a tight association of transferrin with inflammation mediator IL-10 in COVID-19 patients, which was proved to be mainly governed by the monocyte/macrophage of liver, shedding light on new pathophysiological and immune regulatory mechanisms of COVID-19 disease. We finally validated the beneficial effects of iron chelators as anti-viral agents in SARS-CoV-2-infected K18-hACE2 mice through modulation of iron dyshomeostasis and alleviating inflammation response. Our findings highlight the critical role of liver-mediated iron dysregulation in COVID-19 disease severity, providing solid evidence on the involvement of iron-related proteins in COVID-19 pathophysiology and immunity.

Pharmacogenomics of Drugs Used in ß-Thalassemia and Sickle-Cell Disease: From Basic Research to Clinical Applications.

In this short review we have presented and discussed studies on pharmacogenomics (also termed pharmacogenetics) of the drugs employed in the treatment of ß-thalassemia or Sickle-cell disease (SCD). This field of investigation is relevant, since it is expected to help clinicians select the appropriate drug and the correct dosage for each patient. We first discussed the search for DNA polymorphisms associated with a high expression of γ-globin genes and identified this using GWAS studies and CRISPR-based gene editing approaches. We then presented validated DNA polymorphisms associated with a high HbF production (including, but not limited to the HBG2 XmnI polymorphism and those related to the BCL11A, MYB, KLF-1, and LYAR genes). The expression of microRNAs involved in the regulation of γ-globin genes was also presented in the context of pharmacomiRNomics. Then, the pharmacogenomics of validated fetal hemoglobin inducers (hydroxyurea, butyrate and butyrate analogues, thalidomide, and sirolimus), of iron chelators, and of analgesics in the pain management of SCD patients were considered. Finally, we discuss current clinical trials, as well as international research networks focusing on clinical issues related to pharmacogenomics in hematological diseases.

The decline in cellular iron is crucial for differentiation in keratinocytes.

Iron is a vital metal for most biological functions in tissues, and its concentration is exquisitely regulated at the cellular level. During the process of differentiation, keratinocytes in the epidermis undergo a noticeable reduction in iron content. Conversely, psoriatic lesions, characterized by disruptions in epidermal differentiation, frequently reveal an excessive accumulation of iron within keratinocytes that have undergone differentiation. In this study, we clarified the significance of attenuated cellular iron content in the intricate course of epidermal differentiation. We illustrated this phenomenon through the utilization of hinokitiol, an iron chelator derived from the heartwood of Taiwanese hinoki, which forcibly delivers iron into cells independent of the intrinsic iron-regulation systems. While primary cultured keratinocytes readily succumbed to necrotic cell death by this iron chelator, mild administration of the hinokitiol-iron complex modestly disrupts the process of differentiation in these cells. Notably, keratinocyte model cells HaCaT and anaplastic skin rudiments exhibit remarkable resilience against the cytotoxic impact of hinokitiol, and the potent artificial influx of iron explains a suppressive effect selectively on epidermal differentiation. Moreover, the augmentation of iron content induced by the overexpression of divalent metal transporter 1 culminates in the inhibition of differentiation in HaCaT cells. Consequently, the diminution in cellular iron content emerges as an important determinant influencing the trajectory of keratinocyte differentiation.

Real-world evidence: Long-term safety of deferiprone in a large cohort of patients with sickle cell disease enrolled in a registry for up to 10 years.

Patients with sickle cell disease (SCD) and other anemias who receive blood transfusions are at risk of organ damage due to transfusional iron overload. Deferiprone is an iron chelator with a well-established safety and efficacy profile that is indicated for the treatment of transfusional iron overload. Here, we report safety data from the large-scale, retrospective Ferriprox® Total Care Registry, which involved all patients with SCD taking deferiprone following the 2011 approval of deferiprone in the United States through August 2020. A total of 634 patients who had initiated deferiprone treatment were included. The mean (SD) duration of deferiprone exposure in the registry was 1.6 (1.6) years (range 0 to 9.7 years). In the overall patient population (N = 634), 64.7% (n = 410) of patients reported a total of 1885 adverse events (AEs). In subgroup analyses, 54.6% (n = 71) of pediatric patients and 67.3% (n = 339) of adult patients reported AEs. The most common AEs reported in patients receiving deferiprone were sickle cell crisis (22.7%), nausea (12.1%), vomiting (8.7%), abdominal discomfort (5.4%), and fatigue (5.4%). Neutropenia was reported in four (0.6%) patients and severe neutropenia/agranulocytosis (defined as absolute neutrophil count <0.5 × 109/L) was reported in two (0.3%) patients. Of patients with evaluable data, all cases of neutropenia and severe neutropenia/agranulocytosis resolved with deferiprone discontinuation. Results from the nearly 10 years of real-world data collected in the Ferriprox® Total Care Registry demonstrate that deferiprone is safe and well tolerated in patients with SCD or other anemias who have transfusional iron overload.

Quantifiable and Inexpensive Cell-Free Fluorescent Method to Confirm the Ability of Novel Compounds to Chelate Iron.

Cancer cells require large amounts of iron to maintain their proliferation. Iron metabolism is considered a hallmark of cancer, making iron a valid target for anti-cancer approaches. The development of novel compounds and the identification of leads for further modification requires that proof of mechanism assays be carried out. There are many assays to evaluate the impact on proliferation; however, the ability to chelate iron is an important and sometimes overlooked end-point measure due to the high costs of equipment and the challenge to quickly and reproducibly quantify the strength of chelation. Here, we describe a quantifiable and inexpensive cell-free fluorescent method to confirm the ability of novel compounds to chelate iron. Our assay relies on the commercially available inexpensive fluorescent dye Calcein, whose fluorescence can be quantified on most fluorescent microtiter plate readers. Calcein is a weak iron chelator, and its fluorescence is quenched when it binds Fe2+/3+; fluorescence is restored when a novel chelator outcompetes Calcein for bound Fe2+/3+. The removal of fluorescent quenching and the resulting increase in fluorescence allows the chelation ability of a novel putative chelator to be determined. Therefore, we offer an inexpensive, high-throughput assay that allows the rapid screening of novel candidate chelator compounds.

Efficacy and Safety of a Dispersible Tablet of GPO-Deferasirox Monotherapy among Children with Transfusion-Dependent Thalassemia and Iron Overload.

The study aimed to determine efficacy and safety of generic deferasirox monotherapy. Deferasirox was administered in transfusion-induced iron overloaded thalassemia. Efficacy was defined as responders and nonresponders by ≤ 15 reduced serum ferritin from baseline. Adverse events were also monitored. Fifty-two patients with mainly Hb E/ß-thalassemia at the mean (SD) age of 8.7 (4.1) years, were enrolled. The mean (SD) daily transfusion iron load was 0.47 (0.1) mg/kg and maximum daily deferasirox was 35.0 (6.2) mg/kg. Altogether, 52, 40 and 18 patients completed the first, second and third years of study, respectively. The median baseline serum ferritin 2,383 ng/mL decreased to 1,478, 1,038 and 1,268 ng/mL at the end of first, second and third years, respectively, with overall response rate at 73.1% (38/52). Patients with baseline serum ferritin >2,500 ng/mL showed a change in serum ferritin higher than those ≤2,500 ng/mL starting from the 9th month of chelation. Adverse events were found in 5 of 52 patients (9.6%) including transaminitis (n = 2), one each of proteinuria, rash and proximal tubular dysfunction which resolved after transient stopping or decreasing the chelation dose. Generic deferasirox was effective and safe among pediatric patients with transfusion-induced iron overloaded thalassemia.

Cardiac effects of deferasirox in transfusion-dependent patients with myelodysplastic syndromes: TELESTO study.

Iron overload from repeated transfusions has a negative impact on cardiac function, and iron chelation therapy may help prevent cardiac dysfunction in transfusion-dependent patients with myelodysplastic syndromes (MDS). TELESTO (NCT00940602) was a prospective, placebo-controlled, randomised study to evaluate the iron chelator deferasirox in patients with low- or intermediate-1-risk MDS and iron overload. Echocardiographic parameters were collected at screening and during treatment. Patients receiving deferasirox experienced a significant decrease in the composite risk of hospitalisation for congestive heart failure (CHF) or worsening of cardiac function (HR = 0.23; 95% CI: 0.05, 0.99; nominal p = 0.0322) versus placebo. No significant differences between the arms were found in left ventricular ejection fraction, ventricular diameter and mass or pulmonary artery pressure. The absolute number of events was low, but the enrolled patients were younger than average for patients with MDS, with no serious cardiac comorbidities and a modest cardiovascular risk profile. These results support the effectiveness of deferasirox in preventing cardiac damage caused by iron overload in this patient population. Identification of patients developing CHF is challenging due to the lack of distinctive echocardiographic features. The treatment of iron overload may be important to prevent cardiac dysfunction in these patients, even those with moderate CHF risk.

Deferasirox: A comprehensive drug profile.

Deferasirox is an iron-chelating drug developed by Novartis company for treatment of diseases accompanied by chronic iron overload; such as ß-thalassemia or sickle cell diseases. Owing to its advantages such as high affinity, specificity and wide therapeutic window, it is considered as first line treatment. The current chapter describes the physicochemical characteristics, mode of action, pharmacokinetics, therapeutic applications and synthetic methods for deferasirox. Moreover, it includes Fourier transform infrared spectrometry (FTIR) and nuclear magnetic resonance spectroscopy (NMR) analysis for its functional groups. In addition, the selected analytical methods are summarized to aid the analysts in their routine analysis of deferasirox.

In vitro lung epithelial cell model reveals novel roles for Pseudomonas aeruginosa siderophores.

The multidrug-resistant pathogen Pseudomonas aeruginosa is a common nosocomial respiratory pathogen that continues to threaten the lives of patients with mechanical ventilation in intensive care units and those with underlying comorbidities such as cystic fibrosis or chronic obstructive pulmonary disease. For over 20 years, studies have repeatedly demonstrated that the major siderophore pyoverdine is an important virulence factor for P. aeruginosa in invertebrate and mammalian hosts in vivo. Despite its physiological significance, an in vitro, mammalian cell culture model that can be used to characterize the impact and molecular mechanisms of pyoverdine-mediated virulence has only been developed very recently. In this study, we adapt a previously-established, murine macrophage-based model to use human bronchial epithelial (16HBE) cells. We demonstrate that conditioned medium from P. aeruginosa induced rapid 16HBE cell death through the pyoverdine-dependent secretion of cytotoxic rhamnolipids. Genetic or chemical disruption of pyoverdine biosynthesis decreased rhamnolipid production and mitigated cell death. Consistent with these observations, chemical depletion of lipids or genetic disruption of rhamnolipid biosynthesis abrogated the toxicity of the conditioned medium. Furthermore, we also examine the effects of exposure to purified pyoverdine on 16HBE cells. While pyoverdine accumulated within cells, it was largely sequestered within early endosomes, resulting in minimal cytotoxicity. More membrane-permeable iron chelators, such as the siderophore pyochelin, decreased epithelial cell viability and upregulated several pro-inflammatory genes. However, pyoverdine potentiated these iron chelators in activating pro-inflammatory pathways. Altogether, these findings suggest that the siderophores pyoverdine and pyochelin play distinct roles in virulence during acute P. aeruginosa lung infection. IMPORTANCE: Multidrug-resistant Pseudomonas aeruginosa is a versatile bacterium that frequently causes lung infections. This pathogen is life-threatening to mechanically-ventilated patients in intensive care units and is a debilitating burden for individuals with cystic fibrosis. However, the role of P. aeruginosa virulence factors and their regulation during infection are not fully understood. Previous murine lung infection studies have demonstrated that the production of siderophores (e.g., pyoverdine and pyochelin) is necessary for full P. aeruginosa virulence. In this report, we provide further mechanistic insight into this phenomenon. We characterize distinct and novel ways these siderophores contribute to virulence using an in vitro human lung epithelial cell culture model.