Therapeutic applications of chelating drugs in iron metabolic disorders of the brain and retina

Deferoxamine attenuates visual impairment in retinal ischemia‒reperfusion via inhibiting ferroptosis

Retinal ischemia‒reperfusion (I/R) injury can cause significant damage to human retinal neurons, greatly compromising their functions. Existing interventions have been proven to have little effect. Ferroptosis is a newly discovered type of programmed cell death that has been found to be involved in the process of ischemia‒reperfusion in multiple organs throughout the body. Studies have shown that it is also present in retinal ischemia‒reperfusion injury. A rat model of retinal ischemia‒reperfusion injury was constructed and treated with deferoxamine. In this study, we found the accumulation of Fe2+, reactive oxygen species (ROS), malondialdehyde (MDA), and the consumption of glutathione (GSH) via ELISA testing; increased expression of transferrin; and decreased expression of ferritin, SLC7A11, and GPX4 via Western blotting (WB) and real-time PCR testing. Structural signs of ferroptosis (mitochondrial shrinkage) were observed across multiple cell types, including retinal ganglion cells (RGCs), photoreceptor cells, and pigment epithelial cells. Changes in visual function were detected by F-VEP and ERG. The results showed that iron and oxidative stress were increased in the retinal ischemia‒reperfusion injury model, resulting in ferroptosis and tissue damage. Deferoxamine protects the structural and functional soundness of the retina by inhibiting ferroptosis through the simultaneous inhibition of hemochromatosis, the initiation of transferrin, and the degradation of ferritin and activating the antioxidant capacity of the System Xc-GSH-GPX4 pathway.

Challenges and Opportunities of Metal Chelation Therapy in Trace Metals Overload-Induced Alzheimer's Disease

Essential trace metals like zinc (Zn), iron (Fe), and copper (Cu) play an important physiological role in the metabolomics and healthy functioning of body organs, including the brain. However, abnormal accumulation of trace metals in the brain and dyshomeostasis in the different regions of the brain have emerged as contributing factors in neuronal degeneration, Aβ aggregation, and Tau formation. The link between these essential trace metal ions and the risk of AD has been widely studied, although the conclusions have been ambiguous. Despite the absence of evidence for any clinical benefit, therapeutic chelation is still hypothesized to be a therapeutic option for AD. Furthermore, the parameters like bioavailability, ability to cross the BBB, and chelation specificity must be taken into consideration while selecting a suitable chelation therapy. The data in this review summarizes that the primary intervention in AD is brain metal homeostasis along with brain metal scavenging. This review evaluates the impact of different trace metals (Cu, Zn, Fe) on normal brain functioning and their association with neurodegeneration in AD. Also, it investigates the therapeutic potential of metal chelators in the management of AD. An extensive literature search was carried out on the "Web of Science, PubMed, Science Direct, and Google Scholar" to investigate the effect of trace elements in neurological impairment and the role of metal chelators in AD. In addition, the current review highlights the advantages and limitations of chelation therapies and the difficulties involved in developing selective metal chelation therapy in AD patients.

Ferulic acid alleviates retinal neovascularization by modulating microglia/macrophage polarization through the ROS/NF-κB axis

Inflammation plays a pivotal role in ischemia-induced retinal neovascularization. Targeting microglia/macrophage-based neuroinflammation presents a promising therapeutic strategy. Ferulic acid (FA), a natural and active ingredient in plants, exerts favorable anti-oxidative and anti-inflammatory activities. In this study, we investigated the inhibitory effect of FA against hypoxia-induced retinal angiogenesis using cultured retinal vascular endothelial cells and an oxygen-induced retinopathy mouse (OIR) model. The immunoregulatory effect of FA on microglia/macrophage polarization was evaluated by detecting the expression of specific markers for both pro-inflammatory “M1” and anti-inflammatory “M2” phenotypes using co-immunostaining and polymerase chain reaction assays. The underlying molecular mechanism upon FA treatment was also explored. The results showed that FA supplement markedly inhibited retinal pathological angiogenesis both in vivo and in vitro. In addition, FA switched microglia/macrophage polarization from “M1” towards “M2” phenotype and alleviated the inflammatory response. Mechanically, the anti-angiogenic and anti-inflammatory properties of FA were mainly due to blockade of the ROS/NF-κB pathway. Our data demonstrated an anti-angiogenic effect of FA through regulating M1-to-M2 microglia/macrophage polarization, suggesting a potential therapeutic strategy for retinal neovascular diseases.

Inherited Retinal Dystrophies: Role of Oxidative Stress and Inflammation in Their Physiopathology and Therapeutic Implications

Inherited retinal dystrophies (IRDs) are a large group of genetically and clinically heterogeneous diseases characterized by the progressive degeneration of the retina, ultimately leading to loss of visual function. Oxidative stress and inflammation play fundamental roles in the physiopathology of these diseases. Photoreceptor cell death induces an inflammatory state in the retina. The activation of several molecular pathways triggers different cellular responses to injury, including the activation of microglia to eliminate debris and recruit inflammatory cells from circulation. Therapeutical options for IRDs are currently limited, although a small number of patients have been successfully treated by gene therapy. Many other therapeutic strategies are being pursued to mitigate the deleterious effects of IRDs associated with oxidative metabolism and/or inflammation, including inhibiting reactive oxygen species’ accumulation and inflammatory responses, and blocking autophagy. Several compounds are being tested in clinical trials, generating great expectations for their implementation. The present review discusses the main death mechanisms that occur in IRDs and the latest therapies that are under investigation.

Calcium channels and iron metabolism: A redox catastrophe in Parkinson's disease and an innovative path to novel therapies?

Autonomously spiking dopaminergic neurons of the substantia nigra pars compacta (SNpc) are exquisitely specialized and suffer toxic iron-loading in Parkinson's disease (PD). However, the molecular mechanism involved remains unclear and critical to decipher for designing new PD therapeutics. The long-lasting (L-type) Ca_V1.3 voltage-gated calcium channel is expressed at high levels amongst nigral neurons of the SNpc, and due to its role in calcium and iron influx, could play a role in the pathogenesis of PD. Neuronal iron uptake via this route could be unregulated under the pathological setting of PD and potentiate cellular stress due to its redox activity. This Commentary will focus on the role of the Ca_V1.3 channels in calcium and iron uptake in the context of pharmacological targeting. Prospectively, the audacious use of artificial intelligence to design innovative Ca_V1.3 channel inhibitors could lead to breakthrough pharmaceuticals that attenuate calcium and iron entry to ameliorate PD pathology.

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.

Reflections of an aging free radical

In this mini-reflection, I explain how during my doctoral work in a Botany Department I first became interested in H2O2 and later in my career in other reactive oxygen species, especially the role of "catalytic" iron and haem compounds (including leghaemoglobin) in promoting oxidative damage. The important roles that H2O2, other ROS and dietary plants play in respect to humans are discussed. I also review the roles of diet-derived antioxidants in relation to human disease, presenting reasons why clinical trials using high doses of natural antioxidants have generally given disappointing results. Iron chelators and ergothioneine are reviewed as potential cytoprotective agents with antioxidant properties that may be useful therapeutically. The discovery of ferroptosis may also lead to novel agents that can be used to treat certain diseases.