Iron chelation in the treatment of neurodegenerative diseases

Cerebral iron accumulation in multiple sclerosis: Pathophysiology and therapeutic implications

Multiple sclerosis (MS) is a chronic autoimmune disorder of the central nervous system characterized by demyelination, neuroinflammation, and neurodegeneration. Recent studies highlight the role of cerebral iron (Fe) accumulation in exacerbating MS pathophysiology. Fe, essential for neural function, contributes to oxidative stress and inflammation when dysregulated, particularly in the brain's gray matter and demyelinated lesions. Advanced imaging techniques, including susceptibility-weighted and quantitative susceptibility mapping, have revealed abnormal Fe deposition patterns in MS patients, suggesting its involvement in disease progression. Iron's interaction with immune cells, such as microglia, releases pro-inflammatory cytokines, further amplifying neuroinflammation and neuronal damage. These findings implicate Fe dysregulation as a significant factor in MS progression, contributing to clinical manifestations like cognitive impairment. Therapeutic strategies targeting Fe metabolism, including Fe chelation therapies, show promise in reducing Fe-related damage, instilling optimism about the future of MS treatment. However, challenges such as crossing the blood-brain barrier and maintaining Fe homeostasis remain. Emerging approaches, such as Fe-targeted nanotherapeutics and biologics, offer new possibilities for personalized treatments. However, the journey is far from over. Continued research into the molecular mechanisms of Fe-induced neuroinflammation and oxidative damage is essential. Through this research, we can develop effective interventions that could slow MS progression and improve patient outcomes.

Does drug repurposing bridge the gaps in management of Parkinson's disease? Unravelling the facts and fallacies

Repurposing the existing drugs for the management of both common and rare diseases is increasingly appealing due to challenges such as high attrition rates, the economy, and the slow pace of discovering new drugs. Drug repurposing involves the utilization of existing medications to treat diseases for which they were not originally intended. Despite encountering scientific and economic challenges, the pharmaceutical industry is intrigued by the potential to uncover new indications for medications. Medication repurposing is applicable across different stages of drug development, with the greatest potential observed when the drug has undergone prior safety testing. In this review, strategies for repurposing drugs for Parkinson's disease (PD) are outlined, a neurodegenerative disorder predominantly impacting dopaminergic neurons in the substantia nigra pars compacta region. PD is a debilitating neurodegenerative condition marked by an amalgam of motor and non-motor symptoms. Despite the availability of certain symptomatic treatments, particularly targeting motor symptoms, there remains a lack of established drugs capable of modifying the clinical course of PD, leading to its unchecked progression. Although standard drug discovery initiatives focusing on treatments that relieve diseases have yielded valuable understanding into the underlying mechanisms of PD, none of the numerous promising candidates identified in preclinical studies have successfully transitioned into clinically effective medications. Due to the substantial expenses associated with drug discovery endeavors, it is understandable that there has been a notable shift towards drug reprofiling strategies. Assessing the efficacy of an existing medication offers the additional advantage of circumventing the requirement for preclinical safety assessments and formulation enhancements, consequently streamlining the process and reducing both the duration of time and financial investments involved in bringing a treatment to clinical fruition. Furthermore, repurposed drugs may benefit from lower rates of failure, presenting an additional potential advantage. Various strategies for repurposing drugs are available to researchers in the field of PD. Some of these strategies have demonstrated effectiveness in identifying appropriate drugs for clinical trials, thereby providing validation for such strategies. This review provides an overview of the diverse strategies employed for drug reprofiling from approaches that place emphasis on single-gene transcriptional investigations to comprehensive epidemiological correlation analysis. Additionally, instances of previous or current research endeavors employing each strategy have been discussed. For the strategies that have not been yet implemented in PD research, their strategic efficacy is demonstrated using examples involving other disorders. In this review, we assess the safety and efficacy potential of prominent candidates repurposed as potential treatments for modifying the course of PD undergoing advanced clinical trials.

Major heme proteins hemoglobin and myoglobin with respect to their roles in oxidative stress - a brief review

Oxidative stress is considered as the root-cause of different pathological conditions. Transition metals, because of their redox-active states, are capable of free radical generation contributing oxidative stress. Hemoglobin and myoglobin are two major heme proteins, involved in oxygen transport and oxygen storage, respectively. Heme prosthetic group of heme proteins is a good reservoir of iron, the most abundant transition metal in human body. Although iron is tightly bound in the heme pocket of these proteins, it is liberated under specific circumstances yielding free ferrous iron. This active iron can react with H2O2, a secondary metabolite, forming hydroxyl radical via Fenton reaction. Hydroxyl radical is the most harmful free radical among all the reactive oxygen species. It causes oxidative stress by damaging lipid membranes, proteins and nucleic acids, activating inflammatory pathways and altering membrane channels, resulting disease conditions. In this review, we have discussed how heme-irons of hemoglobin and myoglobin can promote oxidative stress under different pathophysiological conditions including metabolic syndrome, diabetes, cardiovascular, neurodegenerative and renal diseases. Understanding the association of heme proteins to oxidative stress may be important for knowing the complications as well as therapeutic management of different pathological conditions.

Ceruloplasmin administration in the preclinical mouse model of aceruloplasminemia reveals a sex-related variation in biodistribution

Mutations in the ceruloplasmin (CP) gene are responsible for the rare genetic disease aceruloplasminemia characterized by iron accumulation in different organs, including the brain. We previously reported that administration of purified CP in the CP-deficient (cpKO) mouse model of the disease, was therapeutically effective. Here we evaluated the bioavailability of the therapeutic protein in different organs of the cpKO mouse. The distribution of administered radiolabelled-[64Cu]-CP was assessed in brain and peripheral tissues in vivo and ex vivo. The uptake of [64Cu]-CP in cpKO mice varied according to animal sex and age, with a higher accumulation in the cerebellum and liver of males at 6 months of age, while higher levels were observed in the same organs in females at 10 months. Sex-specific variations in the uptake of radiolabelled-CP were genotype-associated, by comparison with wild type mice. Based on these findings, we assessed sex effects on the therapeutic efficacy of the CP-replacement therapy previously performed. Multivariate analysis confirmed that the therapeutic effect was present for both sexes, and this was more pronounced in males than females. Therefore, sex-related variation in CP tissue bioavailability point to the possibility of sex-specific therapeutic regimens in the design of future CP-replacement therapies for aceruloplasminemia.

Ferroptosis in schizophrenia: Mechanisms and therapeutic potentials (Review)

Schizophrenia, a complex psychiatric disorder, presents with multifaceted symptoms and important challenges in treatment, primarily due to its pathophysiological complexity, which involves oxidative stress and aberrant iron metabolism. Recent insights into ferroptosis, a unique form of iron‑dependent cell death characterized by lipid peroxidation and antioxidant system failures, open new avenues for understanding the neurobiological foundation of schizophrenia. The present review explores the interplay between ferroptosis and schizophrenia, emphasizing the potential contributions of disrupted iron homeostasis and oxidative mechanisms to the pathology and progression of this disease. The emerging evidence linking ferroptosis with the oxidative stress observed in schizophrenia provides a compelling narrative for re‑evaluating current therapeutic strategies and exploring novel interventions targeting these molecular pathways, such as the glutathione peroxidase 4 pathway and the ferroptosis suppressor protein 1 pathway. By integrating recent advances in ferroptosis research, the current review highlights innovative therapeutic potentials, including N‑acetylcysteine, selenium, omega‑3 fatty acids and iron chelation therapy, which could address the limitations of existing treatments and improve clinical outcomes for individuals with schizophrenia.

Targeting ferroptosis in autoimmune diseases: Mechanisms and therapeutic prospects

Ferroptosis is a form of regulated cell death that relies on iron and exhibits unique characteristics, including disrupted iron balance, reduced antioxidant defenses, and abnormal lipid peroxidation. Recent research suggests that ferroptosis is associated with the onset and progression of autoimmune disorders such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and multiple sclerosis (MS). However, the precise effects and molecular mechanisms remain incompletely understood. This article presents an overview of how ferroptosis mechanisms contribute to the development and advancement of autoimmune diseases, as well as the involvement of various immune cells in linking ferroptosis to autoimmune conditions. It also explores potential drug targets within the ferroptosis pathway and recent advancements in therapeutic approaches aimed at preventing and treating autoimmune diseases by targeting ferroptosis. Lastly, the article discusses the challenges and opportunities in utilizing ferroptosis as a potential therapeutic avenue for autoimmune disorders.

Neuropsychological Characteristics and Quantitative Electroencephalography in Skogholt's Disease-A Rare Neurodegenerative Disease in a Norwegian Family

Members of three generations of a Norwegian family (N = 9) with a rare demyelinating disease were studied. Neuropsychological testing was performed using the Mini Mental Status Examination (MMSE), Wechsler Intelligence Scale-III (WAIS-III), and Hopkins Verbal Learning Test-Revised (HVLT-R). EEGs were recorded with grand averaging spectrograms and event-related potentials (ERPs) in rest and cued GO/NOGO task conditions. The results were within the normal range on the MMSE. Full-scale WAIS-III results were in the range of 69-113, with lower scores in verbal understanding than in perceptual organization, and low scores also in indications of working memory and processing speed difficulties. The HVLT-R showed impairment of both immediate and delayed recall. Quantitative EEG showed an increase in low alpha (around 7.5 Hz) activity in the temporofrontal areas, mostly on the left side. There was a deviation in the late (>300 ms) component in response to the NOGO stimuli. A strong correlation (r = 0.78, p = 0.01) between the Hopkins Verbal Learning Test (delayed recall) and the amplitude of the NOGO ERP component was observed. The EEG spectra showed deviations from the healthy controls, especially at frontotemporal deviations. Deviations in the ERP component of the NOGO trials were related to delayed recall in the Hopkins Verbal learning test.

Iron homeostasis in older adults: balancing nutritional requirements and health risks

Iron plays a crucial role in many physiological processes, including oxygen transport, bioenergetics, and immune function. Iron is assimilated from food and also recycled from senescent red blood cells. Iron exists in two dietary forms: heme (animal based) and non-heme (mostly plant based). The body uses iron for metabolic purposes, and stores the excess mainly in splenic and hepatic macrophages. Physiologically, iron excretion in humans is inefficient and not highly regulated, so regulation of intestinal absorption maintains iron homeostasis. Iron losses occur at a steady rate via turnover of the intestinal epithelium, blood loss, and exfoliation of dead skin cells, but overall iron homeostasis is tightly controlled at cellular and systemic levels. Aging can have a profound impact on iron homeostasis and induce a dyshomeostasis where iron deficiency or overload (sometimes both simultaneously) can occur, potentially leading to several disorders and pathologies. To maintain physiologically balanced iron levels, reduce risk of disease, and promote healthy aging, it is advisable for older adults to follow recommended daily intake guidelines and periodically assess iron levels. Clinicians can evaluate body iron status using different techniques but selecting an assessment method primarily depends on the condition being examined. This review provides a comprehensive overview of the forms, sources, and metabolism of dietary iron, associated disorders of iron dyshomeostasis, assessment of iron levels in older adults, and nutritional guidelines and strategies to maintain iron balance in older adults.

Developing Iron Nanochelating Agents: Preliminary Investigation of Effectiveness and Safety for Central Nervous System Applications

Excessive iron levels are believed to contribute to the development of neurodegenerative disorders by promoting oxidative stress and harmful protein clustering. Novel chelation treatments that can effectively remove excess iron while minimizing negative effects on the nervous system are being explored. This study focuses on the creation and evaluation of innovative nanobubble (NB) formulations, shelled with various polymers such as glycol-chitosan (GC) and glycol-chitosan conjugated with deferoxamine (DFO), to enhance their ability to bind iron. Various methods were used to evaluate their physical and chemical properties, chelation capacity in diverse iron solutions and impact on reactive oxygen species (ROS). Notably, the GC-DFO NBs demonstrated the ability to decrease amyloid-β protein misfolding caused by iron. To assess potential toxicity, in vitro cytotoxicity testing was conducted using organotypic brain cultures from the substantia nigra, revealing no adverse effects at appropriate concentrations. Additionally, the impact of NBs on spontaneous electrical signaling in hippocampal neurons was examined. Our findings suggest a novel nanochelation approach utilizing DFO-conjugated NBs for the removal of excess iron in cerebral regions, potentially preventing neurotoxic effects.

Recent Advances in the Treatment Strategies of Friedreich's Ataxia: A Review of Potential Drug Candidates and their Underlying Mechanisms

BACKGROUND

Friedreich's Ataxia (FRDA) is a rare hereditary neurodegenerative disorder characterized by progressive ataxia, cardiomyopathy, and diabetes. The disease is caused by a deficiency of frataxin, a mitochondrial protein involved in iron-sulfur cluster synthesis and iron metabolism.

OBJECTIVE

This review aims to summarize recent advances in the development of treatment strategies for FRDA, with a focus on potential drug candidates and their mechanisms of action.

METHODS

A comprehensive literature search was conducted using various authentic scientific databases to identify studies published in the last decade that investigated potential treatment strategies for FRDA. The search terms used included "Friedreich's ataxia", "treatment", "drug candidates", and "mechanisms of action".

RESULTS

To date, only one drug got approval from US-FDA in the year 2023; however, significant developments were achieved in FRDA-related research focusing on diverse therapeutic interventions that could potentially alleviate the symptoms of this disease. Several promising drug candidates have been identified for the treatment of FRDA, which target various aspects of frataxin deficiency and aim to restore frataxin levels, reduce oxidative stress, and improve mitochondrial function. Clinical trials have shown varying degrees of success, with some drugs demonstrating significant improvements in neurological function and quality of life in FRDA patients.

CONCLUSION

While there has been significant progress in the development of treatment strategies for FRDA, further research is needed to optimize these approaches and identify the most effective and safe treatment options for patients. The integration of multiple therapeutic strategies may be necessary to achieve the best outcomes in FRDA management.

Overall and individual associations between per- and polyfluoroalkyl substances and liver function indices and the metabolic mechanism

Per- and polyfluoroalkyl substances (PFAS) can disrupt liver homeostasis. Studies have shown that a single exposure to PFAS may provoke abnormal liver function; however, few studies have investigated the overall effect of PFAS mixtures. We aimed to investigate associations between exposure to PFAS mixtures and liver function indices and explore the relevant mechanisms. This study included 278 adult males from Guangzhou, China. Serum metabolite profiles were analyzed using untargeted metabolomics. We applied weighted quantile sum (WQS) regression as well as Bayesian kernel machine regression (BKMR) to analyze the association of nine PFAS mixtures with 14 liver function indices. PFAS mixtures were positively associated with apolipoprotein B (APOB) and gamma-glutamyltransferase (GGT) and negatively associated with direct bilirubin (DBIL) and total bilirubin (TBIL) in both the WQS and BKMR analyses. In addition, Spearman's correlation test showed individual PFAS correlated with APOB, GGT, TBIL, and DBIL, while there's little correlation between individual PFAS and other liver function indices. In linear regression analysis, PFHxS, PFOS, PFHpS, PFNA, PFDA, and PFUdA were associated with APOB; PFOA, PFDA, PFOS, PFNA, and PFUdA were associated with GGT. Subsequently, a metabolome-wide association study and mediation analysis were combined to explore metabolites that mediate these associations. The mechanisms linking PFAS to APOB and GGT are mainly related with amino acid and glycerophospholipid metabolism. High-dimensional mediation analysis showed that glycerophospholipids are the main markers of the association between PFAS and APOB, and that (R)-dihydromaleimide, Ile Leu, (R)-(+)-2-pyrrolidone-5-carboxylic acid, and L-glutamate are the main markers of the association between PFAS and GGT. In summary, overall associations between PFAS and specific indices of liver function were found using two statistical methods; the metabolic pathways and markers identified here may serve to prompt more detailed study in animal-based systems, as well as a similar detailed analysis in other populations.

Research on ferroptosis as a therapeutic target for the treatment of neurodegenerative diseases

Ferroptosis is an iron- and lipid peroxidation (LPO)-mediated programmed cell death type. Recently, mounting evidence has indicated the involvement of ferroptosis in neurodegenerative diseases, especially in Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and so on. Treating ferroptosis presents opportunities as well as challenges for neurodegenerative diseases. This review provides a comprehensive overview of typical features of ferroptosis and the underlying mechanisms that contribute to its occurrence, as well as their implications in the pathogenesis and advancement of major neurodegenerative disorders. Meanwhile, we summarize the utilization of ferroptosis inhibition in both experimental and clinical approaches for the treatment of major neurodegenerative disorders. In addition, we specifically summarize recent advances in developing therapeutic means targeting ferroptosis in these diseases, which may guide future approaches for the effective management of these devastating medical conditions.

Novel mutations and molecular pathways identified in patients with brain iron accumulation disorders

Brain iron accumulation disorders (BIADs) are a group of diseases characterized by iron overload in deep gray matter nuclei, which is a common feature of neurodegenerative diseases. Although genetic factors have been reported to be one of the etiologies, much more details about the genetic background and molecular mechanism of BIADs remain unclear. This study aimed to illustrate the genetic characteristics of BIADs and clarify their molecular mechanisms. A total of 84 patients with BIADs were recruited from April 2018 to October 2022 at Xuanwu Hospital. Clinical characteristics including family history, consanguineous marriage history, and age at onset (AAO) were collected and assessed by two senior neurologists. Neuroimaging data were conducted for all the patients, including cranial magnetic resonance imaging (MRI) and susceptibility-weighted imaging (SWI). Whole-exome sequencing (WES) and capillary electrophoresis for detecting sequence mutation and trinucleotide repeat expansion, respectively, were conducted on all patients and part of their parents (whose samples were available). Variant pathogenicity was assessed according to the American College of Medical Genetics and Association for Molecular Pathology (ACMG/AMP). The NBIA and NBIA-like genes with mutations were included for bioinformatic analysis, using Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genome (KEGG). GO annotation and KEGG pathway analysis were performed on Metascape platform. In the 84 patients, 30 (35.7%) were found to carry mutations, among which 20 carried non-dynamic mutations (missense, stop-gained, frameshift, inframe, and exonic deletion) and 10 carried repeat expansion mutations. Compared with sporadic cases, familial cases had more genetic variants (non-dynamic mutation: P=0.025, dynamic mutation: P=0.003). AAO was 27.85±10.42 years in cases with non-dynamic mutations, which was significantly younger than those without mutations (43.13±17.17, t=3.724, P<0.001) and those with repeated expansions (45.40±8.90, t=4.550, P<0.001). Bioinformatic analysis suggested that genes in lipid metabolism, autophagy, mitochondria regulation, and ferroptosis pathways are more likely to be involved in the pathogenesis of BIADs. This study broadens the genetic spectrum of BIADs and has important implications in genetic counselling and clinical diagnosis. Patients diagnosed as BIADs with early AAO and family history are more likely to carry mutations. Bioinformatic analysis provides new insights into the molecular pathogenesis of BIADs, which may shed lights on the therapeutic strategy for neurodegenerative diseases.

Chelation Combination-A Strategy to Mitigate the Neurotoxicity of Manganese, Iron, and Copper?

The chelating thiol dimercaptosuccinate (DMSA) and the traditional agent D-penicillamine (PSH) are effective in enhancing the urinary excretion of copper (Cu) and lead (Pb) in poisoned individuals. However, DMSA, PSH, EDTA (ethylenediamine tetraacetate), and deferoxamine (DFOA) are water-soluble agents with limited access to the central nervous system (CNS). Strategies for mobilization of metals such as manganese (Mn), iron (Fe), and Cu from brain deposits may require the combined use of two agents: one water-soluble agent to remove circulating metal into urine, in addition to an adjuvant shuttler to facilitate the brain-to-blood mobilization. The present review discusses the chemical basis of metal chelation and the ligand exchange of metal ions. To obtain increased excretion of Mn, Cu, and Fe, early experiences showed promising results for CaEDTA, PSH, and DFOA, respectively. Recent experiments have indicated that p-amino salicylate (PAS) plus CaEDTA may be a useful combination to remove Mn from binding sites in CNS, while the deferasirox-DFOA and the tetrathiomolybdate-DMSA combinations may be preferable to promote mobilization of Fe and Cu, respectively, from the CNS. Further research is requested to explore benefits of chelator combinations.

Aceruloplasminemia presenting with microcytic anemia in a Turkish boy due to a novel pathogenic variant

Aceruloplasminemia inherited autosomal recessively in the ceruloplasmin gene is a progressive disease with iron accumulation in various organs such as the brain, liver, pancreas, and retina. Ceruloplasmin gene encodes ceruloplasmin protein, which has ferroxidase activity and is involved in copper and iron metabolism. Progressive neurotoxicity, retinopathy, and diabetes may develop in about 40-60 decades. In addition, microcytic anemia accompanied by high ferritin and low ceruloplasmin level that develop at earlier ages can be first manifestation. Iron chelation may be utilized in the treatment to reduce the toxicity. Early diagnosis and treatment may delay the onset of symptoms. A 14-year-old male patient was followed up with microcytic anemia since an eight-years old. Anemia was accompanied by microcytosis, high ferritin, and low copper and ceruloplasmin levels. A novel homozygous c.690delG variant was detected in ceruloplasmin by whole exome sequencing. Clinical, laboratory and imaging findings of the patient demonstrated aceruloplasminemia. We present a boy with persistent microcytic anemia of the first manifestation at the age of eight, as the youngest case of aceruloplasminemia in the literature. Thereby, aceruloplasminemia should be kept in mind in the etiology of microcytic anemia whose cause couldn't found in childhood.

The neuroprotective effects of glucagon-like peptide 1 in Alzheimer's and Parkinson's disease: An in-depth review

Currently, there is no disease-modifying treatment available for Alzheimer's and Parkinson's disease (AD and PD) and that includes the highly controversial approval of the Aβ-targeting antibody aducanumab for the treatment of AD. Hence, there is still an unmet need for a neuroprotective drug treatment in both AD and PD. Type 2 diabetes is a risk factor for both AD and PD. Glucagon-like peptide 1 (GLP-1) is a peptide hormone and growth factor that has shown neuroprotective effects in preclinical studies, and the success of GLP-1 mimetics in phase II clinical trials in AD and PD has raised new hope. GLP-1 mimetics are currently on the market as treatments for type 2 diabetes. GLP-1 analogs are safe, well tolerated, resistant to desensitization and well characterized in the clinic. Herein, we review the existing evidence and illustrate the neuroprotective pathways that are induced following GLP-1R activation in neurons, microglia and astrocytes. The latter include synaptic protection, improvements in cognition, learning and motor function, amyloid pathology-ameliorating properties (Aβ, Tau, and α-synuclein), the suppression of Ca2+ deregulation and ER stress, potent anti-inflammatory effects, the blockage of oxidative stress, mitochondrial dysfunction and apoptosis pathways, enhancements in the neuronal insulin sensitivity and energy metabolism, functional improvements in autophagy and mitophagy, elevated BDNF and glial cell line-derived neurotrophic factor (GDNF) synthesis as well as neurogenesis. The many beneficial features of GLP-1R and GLP-1/GIPR dual agonists encourage the development of novel drug treatments for AD and PD.

Reversal of genetic brain iron accumulation by N,N'-bis(2-mercaptoethyl)isophthalamide, a lipophilic metal chelator, in mice

N,N'-bis(2-mercaptoethyl)isophthalamide (NBMI) is a novel lipophilic metal chelator and antioxidant used in mercury poisoning. Recent studies have suggested that NBMI may also bind to other metals such as lead and iron. Since NBMI can enter the brain, we evaluated if NBMI removes excess iron from the iron-loaded brain and ameliorates iron-induced oxidative stress. First, NBMI exhibited preferential binding to ferrous (Fe²⁺) iron with a negligible binding affinity to ferric (Fe³⁺) iron, indicating a selective chelation of labile iron. Second, NBMI protected SH-SY5Y human neuroblastoma cells from the cytotoxic effects of high iron. NBMI also decreased cellular labile iron and lessened the production of iron-induced reactive oxygen species in these cells. Deferiprone (DFP), a commonly used oral iron chelator, failed to prevent iron-induced cytotoxicity or labile iron accumulation. Next, we validated the efficacy of NBMI in Hfe H67D mutant mice, a mouse model of brain iron accumulation (BIA). Oral gavage of NBMI for 6 weeks decreased iron accumulation in the brain as well as liver, whereas DFP showed iron chelation only in the liver, but not in the brain. Notably, depletion of brain copper and anemia were observed in BIA mice treated with DFP, but not with NBMI, suggesting a superior safety profile of NBMI over DFP for long-term use. Collectively, our study demonstrates that NBMI provides a neuroprotective effect against BIA and has therapeutic potential for neurodegenerative diseases associated with BIA.

Cerebral Iron Deposition in Neurodegeneration

Disruption of cerebral iron regulation appears to have a role in aging and in the pathogenesis of various neurodegenerative disorders. Possible unfavorable impacts of iron accumulation include reactive oxygen species generation, induction of ferroptosis, and acceleration of inflammatory changes. Whole-brain iron-sensitive magnetic resonance imaging (MRI) techniques allow the examination of macroscopic patterns of brain iron deposits in vivo, while modern analytical methods ex vivo enable the determination of metal-specific content inside individual cell-types, sometimes also within specific cellular compartments. The present review summarizes the whole brain, cellular, and subcellular patterns of iron accumulation in neurodegenerative diseases of genetic and sporadic origin. We also provide an update on mechanisms, biomarkers, and effects of brain iron accumulation in these disorders, focusing on recent publications. In Parkinson’s disease, Friedreich’s disease, and several disorders within the neurodegeneration with brain iron accumulation group, there is a focal siderosis, typically in regions with the most pronounced neuropathological changes. The second group of disorders including multiple sclerosis, Alzheimer’s disease, and amyotrophic lateral sclerosis shows iron accumulation in the globus pallidus, caudate, and putamen, and in specific cortical regions. Yet, other disorders such as aceruloplasminemia, neuroferritinopathy, or Wilson disease manifest with diffuse iron accumulation in the deep gray matter in a pattern comparable to or even more extensive than that observed during normal aging. On the microscopic level, brain iron deposits are present mostly in dystrophic microglia variably accompanied by iron-laden macrophages and in astrocytes, implicating a role of inflammatory changes and blood–brain barrier disturbance in iron accumulation. Options and potential benefits of iron reducing strategies in neurodegeneration are discussed. Future research investigating whether genetic predispositions play a role in brain Fe accumulation is necessary. If confirmed, the prevention of further brain Fe uptake in individuals at risk may be key for preventing neurodegenerative disorders.

Bromodomains in Human-Immunodeficiency Virus-Associated Neurocognitive Disorders: A Model of Ferroptosis-Induced Neurodegeneration

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) comprise a group of illnesses marked by memory and behavioral dysfunction that can occur in up to 50% of HIV patients despite adequate treatment with combination antiretroviral drugs. Iron dyshomeostasis exacerbates HIV-1 infection and plays a major role in Alzheimer's disease pathogenesis. In addition, persons living with HIV demonstrate a high prevalence of neurodegenerative disorders, indicating that HAND provides a unique opportunity to study ferroptosis in these conditions. Both HIV and combination antiretroviral drugs increase the risk of ferroptosis by augmenting ferritin autophagy at the lysosomal level. As many viruses and their proteins exit host cells through lysosomal exocytosis, ferroptosis-driving molecules, iron, cathepsin B and calcium may be released from these organelles. Neurons and glial cells are highly susceptible to ferroptosis and neurodegeneration that engenders white and gray matter damage. Moreover, iron-activated microglia can engage in the aberrant elimination of viable neurons and synapses, further contributing to ferroptosis-induced neurodegeneration. In this mini review, we take a closer look at the role of iron in the pathogenesis of HAND and neurodegenerative disorders. In addition, we describe an epigenetic compensatory system, comprised of bromodomain-containing protein 4 (BRD4) and microRNA-29, that may counteract ferroptosis by activating cystine/glutamate antiporter, while lowering ferritin autophagy and iron regulatory protein-2. We also discuss potential interventions for lysosomal fitness, including ferroptosis blockers, lysosomal acidification, and cathepsin B inhibitors to achieve desirable therapeutic effects of ferroptosis-induced neurodegeneration.

Effects of Deferasirox in Alzheimer’s Disease and Tauopathy Animal Models

The accumulation of iron may contribute to Alzheimer’s disease (AD) and other tauopathies. The iron chelator desferrioxamine slows disease progression in AD patients. However, desferrioxamine requires injection, which is inconvenient and may hinder compliance. We therefore tested an oral iron chelator, desferasirox (Exjade), in transgenic animal models. Tg2576 mice overexpress the mutant human APP protein and produce the Aβ peptide. JNPL3 mice (Tau/Tau) overexpress the mutant human tau protein. Crossing these produced APP/Tau mice, overexpressing both APP and tau. Treating the three models with 1.6 mg deferasirox thrice weekly from age 8 to 14 months did not affect memory as measured by contextual fear conditioning or motor function as measured by rotarod, but tended to decrease hyperphosphorylated tau as measured by AT8 immunohistochemistry and immunoblotting. Deferasirox might act by decreasing iron, which aggregates tau, or directly binding tau to inhibit aggregation.

High Iron and Iron Household Protein Contents in Perineuronal Net-Ensheathed Neurons Ensure Energy Metabolism with Safe Iron Handling

A subpopulation of neurons is less vulnerable against iron-induced oxidative stress and neurodegeneration. A key feature of these neurons is a special extracellular matrix composition that forms a perineuronal net (PN). The PN has a high affinity to iron, which suggests an adapted iron sequestration and metabolism of the ensheathed neurons. Highly active, fast-firing neurons-which are often ensheathed by a PN-have a particular high metabolic demand, and therefore may have a higher need in iron. We hypothesize that PN-ensheathed neurons have a higher intracellular iron concentration and increased levels of iron proteins. Thus, analyses of cellular and regional iron and the iron proteins transferrin (Tf), Tf receptor 1 (TfR), ferritin H/L (FtH/FtL), metal transport protein 1 (MTP1 aka ferroportin), and divalent metal transporter 1 (DMT1) were performed on Wistar rats in the parietal cortex (PC), subiculum (SUB), red nucleus (RN), and substantia nigra (SNpr/SNpc). Neurons with a PN (PN⁺) have higher iron concentrations than neurons without a PN: PC 0.69 mM vs. 0.51 mM, SUB 0.84 mM vs. 0.69 mM, SN 0.71 mM vs. 0.63 mM (SNpr)/0.45 mM (SNpc). Intracellular Tf, TfR and MTP1 contents of PN⁺ neurons were consistently increased. The iron concentration of the PN itself is not increased. We also determined the percentage of PN⁺ neurons: PC 4%, SUB 5%, SNpr 45%, RN 86%. We conclude that PN⁺ neurons constitute a subpopulation of resilient pacemaker neurons characterized by a bustling iron metabolism and outstanding iron handling capabilities. These properties could contribute to the low vulnerability of PN⁺ neurons against iron-induced oxidative stress and degeneration.

Clinical Association between Gout and Parkinson's Disease: A Nationwide Population-Based Cohort Study in Korea

Background and Objectives: This retrospective cohort study aimed to investigate the association between gout and Parkinson’s disease (PD) in Korea. Materials and Methods: Overall, 327,160 patients with gout and 327,160 age- and sex-matched controls were selected from the Korean National Health Insurance Service (NHIS) database. PD incidence was evaluated by reviewing NHIS records during the period from 2002 to 2019. Patients with a diagnosis of gout (International Classification of Diseases-10 (ICD-10), M10) who were prescribed medications for gout, including colchicine, allopurinol, febuxostat, and benzbromarone for at least 90 days were selected. Patients with PD who were assigned a diagnosis code (ICD-G20) and were registered in the rare incurable diseases (RID) system were extracted. Results: During follow-up, 912 patients with gout and 929 control participants developed PD. The incidence rate (IR) of overall PD (per 1000 person-years) was not significantly different between both groups (0.35 vs. 0.36 in gout and control groups, respectively). The incidence rate ratio (IRR) was 0.98 (95% CI: 0.89–1.07). The cumulative incidence of PD was not significantly different between the groups. No association between gout and PD was identified in univariate analysis (HR = 1.00, 95% CI: 0.91–1.10, p = 0.935). HR increased significantly with old age (HR = 92.08, 198, and 235.2 for 60–69 years, 70–79 years, and over 80 years, respectively), female sex (HR = 1.21, 95% CI: 1.07–1.37, p = 0.002), stroke (HR = 1.95, 95% CI: 1.76–2.16, p < 0.001), and hypertension (HR = 1.16, 95% CI: 1.01–1.34, p = 0.04). Dyslipidemia exhibited an inverse result for PD (HR = 0.6, 95% CI: 0.52–0.68, p < 0.001). Conclusions: This population-based study did not identify an association between gout and PD. Age, female sex, stroke, and hypertension were identified as independent risk factors for PD, and dyslipidemia demonstrated an inverse result for PD.

Oxidative Stress and the Pathophysiology and Symptom Profile of Schizophrenia Spectrum Disorders

Schizophrenia is associated with increased levels of oxidative stress, as reflected by an increase in the concentrations of damaging reactive species and a reduction in anti-oxidant defences to combat them. Evidence has suggested that whilst not the likely primary cause of schizophrenia, increased oxidative stress may contribute to declining course and poor outcomes associated with schizophrenia. Here we discuss how oxidative stress may be implicated in the aetiology of schizophrenia and examine how current understanding relates associations with symptoms, potentially via lipid peroxidation induced neuronal damage. We argue that oxidative stress may be a good target for future pharmacotherapy in schizophrenia and suggest a multi-step model of illness progression with oxidative stress involved at each stage.

Role of Iron in the Molecular Pathogenesis of Diseases and Therapeutic Opportunities

Iron is an essential mineral that serves as a prosthetic group for a variety of proteins involved in vital cellular processes. The iron economy within humans is highly conserved in that there is no proper iron excretion pathway. Therefore, iron homeostasis is highly evolved to coordinate iron acquisition, storage, transport, and recycling efficiently. A disturbance in this state can result in excess iron burden in which an ensuing iron-mediated generation of reactive oxygen species imparts widespread oxidative damage to proteins, lipids, and DNA. On the contrary, problems in iron deficiency either due to genetic or nutritional causes can lead to a number of iron deficiency disorders. Iron chelation strategies have been in the works since the early 1900s, and they still remain the most viable therapeutic approach to mitigate the toxic side effects of excess iron. Intense investigations on improving the efficacy of chelation strategies while being well tolerated and accepted by patients have been a particular focus for many researchers over the past 30 years. Moreover, recent advances in our understanding on the role of iron in the pathogenesis of different diseases (both in iron overload and iron deficiency conditions) motivate the need to develop new therapeutics. We summarized recent investigations into the role of iron in health and disease conditions, iron chelation, and iron delivery strategies. Information regarding small molecule as well as macromolecular approaches and how they are employed within different disease pathogenesis such as primary and secondary iron overload diseases, cancer, diabetes, neurodegenerative diseases, infections, and in iron deficiency is provided.

Rational Design of Novel Therapies for Pantothenate Kinase-Associated Neurodegeneration

BACKGROUND

This review highlights the recent scientific advances that have enabled rational design of novel clinical trials for pantothenate kinase-associated neurodegeneration (PKAN), a rare autosomal recessive neurogenetic disorder associated with progressive neurodegenerative changes and functional impairment. PKAN is caused by genetic variants in the PANK2 gene that result in dysfunction in pantothenate kinase 2 (PANK2) enzyme activity, with consequent disruption of coenzyme A (CoA) synthesis, and subsequent accumulation of brain iron. The clinical phenotype is varied and may include dystonia, rigidity, bradykinesia, postural instability, spasticity, loss of ambulation and ability to communicate, feeding difficulties, psychiatric issues, and cognitive and visual impairment. There are several symptom-targeted treatments, but these do not provide sustained benefit as the disorder progresses.

OBJECTIVES

A detailed understanding of the molecular and biochemical pathogenesis of PKAN has opened the door for the design of novel rationally designed therapeutics that target the underlying mechanisms.

METHODS

Two large double-blind phase 3 clinical trials have been completed for deferiprone (an iron chelation treatment) and fosmetpantotenate (precursor replacement therapy). A pilot open-label trial of pantethine as a potential precursor replacement strategy has also been completed, and a trial of 4-phosphopantetheine has begun enrollment. Several other compounds have been evaluated in pre-clinical studies, and additional clinical trials may be anticipated.

CONCLUSIONS

Experience with these trials has encouraged a critical evaluation of optimal trial designs, as well as the development of PKAN-specific measures to monitor outcomes. PKAN provides a valuable example for understanding targeted drug development and clinical trial design for rare disorders. © 2021 International Parkinson and Movement Disorder Society.

Emerging Disease-Modifying Therapies in Neurodegeneration With Brain Iron Accumulation (NBIA) Disorders

Neurodegeneration with Brain Iron Accumulation (NBIA) is a heterogeneous group of progressive neurodegenerative diseases characterized by iron deposition in the globus pallidus and the substantia nigra. As of today, 15 distinct monogenetic disease entities have been identified. The four most common forms are pantothenate kinase-associated neurodegeneration (PKAN), phospholipase A2 group VI (PLA2G6)-associated neurodegeneration (PLAN), beta-propeller protein-associated neurodegeneration (BPAN) and mitochondrial membrane protein-associated neurodegeneration (MPAN). Neurodegeneration with Brain Iron Accumulation disorders present with a wide spectrum of clinical symptoms such as movement disorder signs (dystonia, parkinsonism, chorea), pyramidal involvement (e.g., spasticity), speech disorders, cognitive decline, psychomotor retardation, and ocular abnormalities. Treatment remains largely symptomatic but new drugs are in the pipeline. In this review, we discuss the rationale of new compounds, summarize results from clinical trials, provide an overview of important results in cell lines and animal models and discuss the future development of disease-modifying therapies for NBIA disorders. A general mechanistic approach for treatment of NBIA disorders is with iron chelators which bind and remove iron. Few studies investigated the effect of deferiprone in PKAN, including a recent placebo-controlled double-blind multicenter trial, demonstrating radiological improvement with reduction of iron load in the basal ganglia and a trend to slowing of disease progression. Disease-modifying strategies address the specific metabolic pathways of the affected enzyme. Such tailor-made approaches include provision of an alternative substrate (e.g., fosmetpantotenate or 4′-phosphopantetheine for PKAN) in order to bypass the defective enzyme. A recent randomized controlled trial of fosmetpantotenate, however, did not show any significant benefit of the drug as compared to placebo, leading to early termination of the trials' extension phase. 4′-phosphopantetheine showed promising results in animal models and a clinical study in patients is currently underway. Another approach is the activation of other enzyme isoforms using small molecules (e.g., PZ-2891 in PKAN). There are also compounds which counteract downstream cellular effects. For example, deuterated polyunsaturated fatty acids (D-PUFA) may reduce mitochondrial lipid peroxidation in PLAN. In infantile neuroaxonal dystrophy (a subtype of PLAN), desipramine may be repurposed as it blocks ceramide accumulation. Gene replacement therapy is still in a preclinical stage.

Three-year follow up of using combination therapy with fresh-frozen plasma and iron chelation in a patient with acaeruloplasminemia

Acaeruloplasminemia is a rare autosomal recessive condition caused by inactivating mutations of the CP gene encoding caeruloplasmin (ferroxidase). Caeruloplasmin is a copper-containing plasma ferroxidase enzyme with a key role in facilitating cellular iron efflux. We describe a case of a patient with acaeruloplasminemia, confirmed by genetic analysis, treated with combination therapy of monthly fresh-frozen plasma (FFP) or Octaplas and iron chelation over a 3-year period. This 19-year-old male was diagnosed at the age of 14 after developing issues with social interaction at school prompting investigation. Prior to this, he had been well with a normal childhood. He was found to have an iron deficient picture with a paradoxically high ferritin, with low serum copper and undetectable caeruloplasmin. Genetic testing identified a homozygous splicing mutation, c.(1713 + delG);(c.1713 + delG), in intron 9 of the caeruloplasmin gene. Ferriscan showed a high liver iron concentration of 5.3 mg/g dry tissue (0.17-1.8). Brain and cardiac T2-weighted magnetic resonance (MR) imaging did not detect iron deposition of the brain or heart respectively. Treatment with monthly Octaplas infusion was commenced alongside deferasirox (540 mg o.d.) in an attempt to increase caeruloplasmin levels and reduce iron overload, respectively. After 3 years of treatment, there was biochemical improvement with a reduction in ferritin from 1084 (12-250) to 457 μg/L, ALT from 87 (<50) to 34 U/L together with improvement in his microcytic anaemia. No significant adverse events occurred. This case report adds further evidence of treatment efficacy and safety of combined FFP and iron chelation therapy in acaeruloplasminemia.

Iron and Ferroptosis as Therapeutic Targets in Alzheimer's Disease

Alzheimer's disease (AD), one of the most common neurodegenerative diseases worldwide, has a devastating personal, familial, and societal impact. In spite of profound investment and effort, numerous clinical trials targeting amyloid-β, which is thought to have a causative role in the disease, have not yielded any clinically meaningful success to date. Iron is an essential cofactor in many physiological processes in the brain. An extensive body of work links iron dyshomeostasis with multiple aspects of the pathophysiology of AD. In particular, regional iron load appears to be a risk factor for more rapid cognitive decline. Existing iron-chelating agents have been in use for decades for other indications, and there are preliminary data that some of these could be effective in AD. Many novel iron-chelating compounds are under development, some with in vivo data showing potential Alzheimer's disease-modifying properties. This heretofore underexplored therapeutic class has considerable promise and could yield much-needed agents that slow neurodegeneration in AD.

Mitochondrial iron metabolism and its role in diseases

Iron is one of the most important elements for life, but excess iron is toxic. Intracellularly, mitochondria are the center of iron utilization requiring sufficient amounts to maintain normal physiologic function. Accordingly, disruption of iron homeostasis could seriously impact mitochondrial function leading to impaired energy state and potential disease development. In this review, we discuss mechanisms of iron metabolism including transport, processing, heme synthesis, iron-sulfur cluster biogenesis and storage. We highlight the vital role of mitochondrial iron in pathologic states including neurodegenerative disorders and sideroblastic anemia.

The dark side of gamma-glutamyltransferase (GGT): Pathogenic effects of an 'antioxidant' enzyme

Having long been regarded as just a member in the cellular antioxidant systems, as well as a clinical biomarker of hepatobiliary diseases and alcohol abuse, gamma-glutamyltransferase (GGT) enzyme activity has been highlighted by more recent research as a critical factor in modulation of redox equilibria within the cell and in its surroundings. Moreover, due to the prooxidant reactions which can originate during its metabolic function in selected conditions, experimental and clinical studies are increasingly involving GGT in the pathogenesis of several important disease conditions, such as atherosclerosis, cardiovascular diseases, cancer, lung inflammation, neuroinflammation and bone disorders. The present article is an overview of the laboratory findings that have prompted an evolution in interpretation of the significance of GGT in human pathophysiology.

A preliminary study of the concentration of metallic elements in the blood of patients with multiple sclerosis as measured by ICP-MS

It is estimated that multiple sclerosis (MS) affects 35,000 Brazilians and 2.5 million individuals worldwide. Many studies have suggested a possible role of metallic elements in the etiology of MS, but their concentration in the blood of MS patients is nonetheless little investigated in Brazil. In this work, these elements were studied through Inductively Coupled Plasma Mass Spectrometry (ICP-MS), whose analysis provides a tool to quantify the concentrations of metal elements in the blood samples of individuals with neurodegenerative disorders. This study aimed to compare the concentration of metallic elements in blood samples from patients with MS and healthy individuals. Blood was collected from 30 patients with multiple sclerosis and compared with the control group. Blood samples were digested in closed vessels using a microwave and ICP-MS was used to determine the concentrations of 12 metallic elements (Ba, Be, Ca, Co, Cr, Cu, Fe, Mg, Mo, Ni, Pb and Zn). In MS patients, we observed a reduction in the concentrations of beryllium, copper, chromium, cobalt, nickel, magnesium and iron. The mean concentration of lead in blood was significantly elevated in the MS group. However, no difference was observed in the concentrations of Mo, Ba, Ca and Zn in blood samples from MS patients and the control group. According to our data, there is a possible role for the concentrations of 8 of the 12 evaluated metallic elements in multiple sclerosis. Abnormalities in transition metals levels in biological matrices have been reported in several neurological diseases.

[Aceruloplasminemia, a rare condition not to be overlooked]

Aceruloplasminemia is a rare iron-overload disease that should be better known by physicians. It is an autosomal recessive disorder due to mutations in ceruloplasmin gene causing systemic iron overload, including cerebral and liver parenchyma. The impairment of ferroxidase ceruloplasmin activity leads to intracellular iron retention leading aceruloplasminemia symptoms. Neurologic manifestations include cognitive impairment, ataxia, extrapyramidal syndrome, abnormal movements, and psychiatric-like syndromes. Physicians should search for aceruloplasminemia in several situations with high ferritin levels: microcytic anaemia, diabetes mellitus, neurological and psychiatric disorders. Diagnosis approach is based on the study of transferrin saturation and hepatic iron content evaluated by magnetic resonance imaging of the liver. Ceruloplasmin dosage is required in case of low transferrin saturation and high hepatic iron content and genetic testing is mandatory in case of serum ceruloplasmin defect. Neurological manifestations occur in the sixties decade and leads to disability. Iron chelators are widely used. Despite their efficacy on systemic and cerebral iron overload, iron chelators tolerance is poor. Early initiation of iron chelation therapy might prevent or slowdown neurodegeneration, highlighting the need for an early diagnosis but their clinical efficacy remains uncertain.

Mitochondria and lipid peroxidation in the mechanism of neurodegeneration: Finding ways for prevention

The world's population aging progression renders age-related neurodegenerative diseases to be one of the biggest unsolved problems of modern society. Despite the progress in studying the development of pathology, finding ways for modifying neurodegenerative disorders remains a high priority. One common feature of neurodegenerative diseases is mitochondrial dysfunction and overproduction of reactive oxygen species, resulting in oxidative stress. Although lipid peroxidation is one of the markers for oxidative stress, it also plays an important role in cell physiology, including activation of phospholipases and stimulation of signaling cascades. Excessive lipid peroxidation is a hallmark for most neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and many other neurological conditions. The products of lipid peroxidation have been shown to be the trigger for necrotic, apoptotic, and more specifically for oxidative stress-related, that is, ferroptosis and neuronal cell death. Here we discuss the involvement of lipid peroxidation in the mechanism of neuronal loss and some novel therapeutic directions to oppose it.

Design and evaluation of bi-functional iron chelators for protection of dopaminergic neurons from toxicants

While the etiology of non-familial Parkinson’s disease (PD) remains unclear, there is evidence that increased levels of tissue iron may be a contributing factor. Moreover, exposure to some environmental toxicants is considered an additional risk factor. Therefore, brain-targeted iron chelators are of interest as antidotes for poisoning with dopaminergic toxicants, and as potential treatment of PD. We, therefore, designed a series of small molecules with high affinity for ferric iron and containing structural elements to allow their transport to the brain via the neutral amino acid transporter, LAT1 (SLC7A5). Five candidate molecules were synthesized and initially characterized for protection from ferroptosis in human neurons. The promising hydroxypyridinone SK4 was characterized further. Selective iron chelation within the physiological range of pH values and uptake by LAT1 were confirmed. Concentrations of 10–20 µM blocked neurite loss and cell demise triggered by the parkinsonian neurotoxicants, methyl-phenyl-pyridinium (MPP⁺) and 6-hydroxydopamine (6-OHDA) in human dopaminergic neuronal cultures (LUHMES cells). Rescue was also observed when chelators were given after the toxicant. SK4 derivatives that either lacked LAT1 affinity or had reduced iron chelation potency showed altered activity in our assay panel, as expected. Thus, an iron chelator was developed that revealed neuroprotective properties, as assessed in several models. The data strongly support the role of iron in dopaminergic neurotoxicity and suggests further exploration of the proposed design strategy for improving brain iron chelation.

Rational design, synthesis and biological evaluation of novel multitargeting anti-AD iron chelators with potent MAO-B inhibitory and antioxidant activity

A series of (3-hydroxypyridin-4-one)-coumarin hybrids were developed and investigated as potential multitargeting candidates for the treatment of Alzheimer's disease (AD) through the incorporation of iron-chelating and monoamine oxidase B (MAO-B) inhibition. This combination endowed the hybrids with good capacity to inhibit MAO-B as well as excellent iron-chelating effects. The pFe³⁺ values of the compounds were ranging from 16.91 to 20.16, comparable to more potent than the reference drug deferiprone (DFP). Among them, compound 18d exhibited the most promising activity against MAO-B, with an IC₅₀ value of 87.9 nM. Moreover, compound 18d exerted favorable antioxidant activity, significantly reversed the amyloid-β_1-42 (Aβ_1-42) induced PC12 cell damage. More importantly, 18d remarkably ameliorated the cognitive dysfunction in a scopolamine-induced mice AD model. In brief, a series of hybrids with potential anti-AD effect were successfully obtained, indicating that the design of iron chelators with MAO-B inhibitory and antioxidant activities is an attractive strategy against AD progression.

Effects of iron chelation therapy on the clinical course of aceruloplasminemia: an analysis of aggregated case reports

Background

Aceruloplasminemia is a rare genetic iron overload disorder, characterized by progressive neurological manifestations. The effects of iron chelation on neurological outcomes have only been described in case studies, and are inconsistent. Aggregated case reports were analyzed to help delineate the disease-modifying potential of treatment.

Methods

Data on clinical manifestations, treatment and neurological outcomes of treatment were collected from three neurologically symptomatic Dutch patients, who received deferiprone with phlebotomy as a new therapeutic approach, and combined with other published cases. Neurological outcomes of treatment were compared between patients starting treatment when neurologically symptomatic and patients without neurological manifestations.

Results

Therapeutic approaches for aceruloplasminemia have been described in 48 patients worldwide, including our three patients. Initiation of treatment in a presymptomatic stage of the disease delayed the estimated onset of neurological manifestations by 10 years (median age 61 years, SE 5.0 vs. median age 51 years, SE 0.6, p = 0.001). Although in 11/20 neurologically symptomatic patients neurological manifestations remained stable or improved during treatment, these patients were treated significantly shorter than patients who deteriorated neurologically (median 6 months vs. median 43 months, p = 0.016). Combined iron chelation therapy with deferiprone and phlebotomy for up to 34 months could be safely performed in our patients without symptomatic anemia (2/3), but did not prevent further neurological deterioration.

Conclusions

Early initiation of iron chelation therapy seems to postpone the onset of neurological manifestations in aceruloplasminemia. Publication bias and significant differences in duration of treatment should be considered when interpreting reported treatment outcomes in neurologically symptomatic patients. Based on theoretical grounds and the observed long-term safety and tolerability in our study, we recommend iron chelation therapy with deferiprone in combination with phlebotomy for aceruloplasminemia patients without symptomatic anemia.

New insights in the mechanisms of impaired redox signaling and its interplay with inflammation and immunity in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune neurological disease characterized by chronic inflammation of the central nervous system (CNS), leading to demyelination and axonal damage and resulting in a range of physical, mental or even psychiatric symptoms. Key role of oxidative stress (OS) in the pathogenesis of MS has been suggested, as indicated by the biochemical analysis of cerebrospinal fluid and blood samples, tissue homogenates, and animal models of multiple sclerosis. OS causes demyelination and neurodegeneration directly, by oxidation of lipids, proteins and DNA but also indirectly, by inducing a dysregulation of the immunity and favoring the state of pro-inflammatory response. In this review, we discuss the interrelated mechanisms of the impaired redox signaling, of which the most important are inflammation-induced production of free radicals by activated immune cells and growth factors, release of iron from myelin sheath during demyelination and mitochondrial dysfunction and consequent energy failure and impaired oxidative phosphorylation. Review also provides an overview of the interplay between inflammation, immunity and OS in MS. Finally, this review also points out new potential targets in MS regarding attenuation of OS and inflammatory response in MS.

New Insights into Oxidative Damage and Iron Associated Impairment in Traumatic Brain Injury

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Traumatic Brain Injury is considered one of the most prevalent causes of death around the world; more than seventy millions of individuals sustain the condition per year. The consequences of traumatic brain injury on brain tissue are complex and multifactorial, hence, the current palliative treatments are limited to improve patients’ quality of life. The subsequent hemorrhage caused by trauma and the ongoing oxidative process generated by biochemical disturbances in the in the brain tissue may increase iron levels and reactive oxygen species. The relationship between oxidative damage and the traumatic brain injury is well known, for that reason, diminishing factors that potentiate the production of reactive oxygen species have a promissory therapeutic use. Iron chelators are molecules capable of scavenging the oxidative damage from the brain tissue and are currently in use for ironoverload- derived diseases.

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Here, we show an updated overview of the underlying mechanisms of the oxidative damage after traumatic brain injury. Later, we introduced the potential use of iron chelators as neuroprotective compounds for traumatic brain injury, highlighting the action mechanisms of iron chelators and their current clinical applications.

Neuroprotection in Parkinson's disease: facts and hopes

Parkinson’s disease (PD) is the second most common neurodegenerative disease worldwide. Behind the symptoms there is a complex pathological mechanism which leads to a dopaminergic cell loss in the substantia nigra pars compacta. Despite the strong efforts, curative treatment has not been found yet. To prevent a further cell death, numerous molecules were tested in terms of neuroprotection in preclinical (in vitro, in vivo) and in clinical studies as well. The aim of this review article is to summarize our knowledge about the extensively tested neuroprotective agents (Search period: 1991–2019). We detail the underlying pathological mechanism and summarize the most important results of the completed animal and clinical trials. Although many positive results have been reported in the literature, there is still no evidence that any of them should be used in clinical practice (Cochrane analysis was performed). Therefore, further studies are needed to better understand the pathomechanism of PD and to find the optimal neuroprotective agent(s).

Targeting Iron Dyshomeostasis for Treatment of Neurodegenerative Disorders

While iron has an important role in the normal functioning of the brain owing to its involvement in several physiological processes, dyshomeostasis has been found in many neurodegenerative disorders, as evidenced by both histopathological and imaging studies. Although the exact causes have remained elusive, the fact that altered iron levels have been found in disparate diseases suggests that iron may contribute to their development and/or progression. As such, the processes involved in iron dyshomeostasis may represent novel therapeutic targets. There are, however, many questions about the exact interplay between neurodegeneration and altered iron homeostasis. Some insight can be gained by considering the parallels with respect to what occurs in healthy aging, which is also characterized by increased iron throughout many regions in the brain along with progressive neurodegeneration. Nevertheless, the exact mechanisms of iron-mediated damage are likely disease specific to a certain degree, given that iron plays a crucial role in many disparate biological processes, which are not always affected in the same way across different neurodegenerative disorders. Moreover, it is not even entirely clear yet whether iron actually has a causative role in all of the diseases where altered iron levels have been noted. For example, there is strong evidence of iron dyshomeostasis leading to neurodegeneration in Parkinson's disease, but there is still some question as to whether changes in iron levels are merely an epiphenomenon in multiple sclerosis. Recent advances in neuroimaging now offer the possibility to detect and monitor iron levels in vivo, which allows for an improved understanding of both the temporal and spatial dynamics of iron changes and associated neurodegeneration compared to post-mortem studies. In this regard, iron-based imaging will likely play an important role in the development of therapeutic approaches aimed at addressing altered iron dynamics in neurodegenerative diseases. Currently, the bulk of such therapies have focused on chelating excess iron. Although there is some evidence that these treatment options may yield some benefit, they are not without their own limitations. They are generally effective at reducing brain iron levels, as assessed by imaging, but clinical benefits are more modest. New drugs that specifically target iron-related pathological processes may offer the possibility to prevent, or at the least, slow down irreversible neurodegeneration, which represents an unmet therapeutic target.

Ironing the mitochondria: Relevance to its dynamics

The mitochondrion is "jack of many trades and master of one". Despite being a master in energy generation, it plays a significant role in other cellular processes, including calcium homeostasis, cell death, and iron metabolism. Since mitochondria employ the majority of cellular iron, it plays a central role in the iron homeostasis. Iron could be a major regulator of mitochondrial dynamics as the excess of iron leads to oxidative stress, which causes a disturbance in mitochondrial dynamics. Remarkably, abnormal iron accumulation has been observed in the brain regions of the neurodegenerative disorders patients. These neurodegenerative disorders are also often associated with the abnormal mitochondrial dynamics. Here in this article, we will mainly discuss the studies focused on unravelling the role of iron in mitochondrial dynamics.