Iron-induced Oxidative Stress Research Articles

Could Alcohol-Related Cognitive Decline Be the Result of Iron-Induced Neuroinflammation?

Excessive and prolonged alcohol use can have long-term severe neurological consequences. The mechanisms involved may be complicated; however, new evidence seems to indicate the involvement of iron accumulation and neuroinflammation. Prolonged alcohol consumption has been linked to the accumulation of iron in specific regions of the brain. Evidence suggests that excess iron in the brain can trigger microglia activation in response. This activation leads to the release of pro-inflammatory cytokines and reactive oxygen species, which can cause damage to neurons and surrounding brain tissue. Additionally, iron-induced oxidative stress and inflammation can disrupt the blood-brain barrier, allowing immune cells from the periphery to infiltrate the brain. This infiltration can lead to further neuroinflammatory responses. Inflammation in the brain subsequently disrupts neuronal networks, impairs synaptic plasticity, and accelerates neuronal cell death. Consequently, cognitive functions such as memory, attention, and decision-making are compromised. Additionally, chronic neuroinflammation can hasten the development and progression of neurodegenerative diseases, further exacerbating cognitive impairment. Therefore, alcohol could act as a trigger for iron-induced neuroinflammation and cognitive decline. Overall, the mechanisms at play here seem to strongly link alcohol with cognitive decline, with neuroinflammation resulting from alcohol-induced iron accumulation playing a pivotal role.

Two 5-Methoxyindole Carboxylic Acid-Derived Hydrazones of Neuropharmacological Interest: Synthesis, Crystal Structure, and Chemiluminescent Study of Radical Scavenging Properties

Given the importance of molecular structure in pharmacological activity and interaction with biological receptors, we conducted a study on the 3,4-dihydroxybenzaldehyde hydrazone derivative of 5-methoxy-indole carboxylic acid (5MICA) and a newly synthesised analogue bearing a 2-methoxy-4-hydroxyphenyl ring using single-crystal X-ray diffraction. We studied the ability of the two compounds to scavenge hypochlorite ions using luminol-enhanced chemiluminescence and their potential to modulate oxidative damage induced by iron on the biologically significant molecules lecithin and deoxyribose in order to evaluate possible antioxidant and prooxidant effects. The X-ray study revealed highly conserved geometry and limited rotation and deformation freedom of the respective indole and phenyl fragments. Interestingly, a conformational difference between the two independent molecules in the asymmetric unit of 3b was found. The X-ray study revealed a combination of hydrogen bonding interactions, short contacts, and π–π stacking stabilizing the specific three-dimensional packing of the molecules of 3a and 3b in the crystal structures. The three-dimensional packing of the molecules of 3b produced a zigzag layering projected along the c-axis. Both compounds effectively decreased luminol-dependent chemiluminescence in model systems with KO2-produced superoxide. They displayed opposite effects when applied in a xanthine/xanthine oxidase system. The hydrazones of 5MICA do not trigger a prooxidant effect or subsequent toxicity under conditions of iron-induced oxidative stress. The 3,4-dihydroxy-substituted derivative demonstrated excellent radical scavenging properties in all model systems, making it the lead compound for the development of compounds with combined neuroprotective and antioxidant properties.

3-(4-methoxyphenyl) acrylic acid halts redox imbalance and modulate purinergic enzyme activity in iron-induced testicular injury

Abstract Various derivatives of cinnamic acid have been reported to possess significant activities such as antioxidant and hepatoprotective, and neuroprotective activities. Interestingly, testicular toxicity has been linked to several causes, with oxidative damage being one of the pathophysiological mechanisms. 3-(4-methoxyphenyl) acrylic acid (1), a derivative of cinnamic acid, was synthesized and then investigated for its effects on iron-induced testicular injury and oxidative stress via ex vivo and in silico studies, respectively. Evaluations were done on KAD-1’s FRAP, DPPH free radical scavenging activity, and iron chelating potential. Through the ex vivo incubation of tissue supernatant and 0.1 mM FeSO4 for 30 min at 37 °C with different concentration of 1, oxidative testicular damage treatments were induced. The scavenging property of 1 increases significantly (p < 0.05) as the concentration increases when compared with the standard quercetin. The MDA, CAT, ATPase, and ENTPDase activities were reduced when testicular damage was induced (p < 0.05). The group treated with 30 mg/mL had the highest level of MDA. A significant rise in GSH level and activity of SOD were observed. The result obtained indicated that 1 has the potential to prevent oxidative testicular toxicity, as evidenced by its capacity to control nucleotide hydrolysis and reduce oxidative stress. Overall, the results of this experimental study point to some possible uses of 3-(4-methoxyphenyl) acrylic acid (1) in the prevention of oxidative testicular dysfunction. Therefore, 3-(4-methoxyphenyl) acrylic acid (1) would be a good product in developing a medication to alleviate male infertility.

Abstract A014: Role of stromal CD10 expression in progression of endometrial and endometriosis-associated cancers

Abstract Endometriosis-associated carcinomas (EACs) and endometrial malignancies have many commonalities yet their pathophysiology, particularly those with high-risk histology such as clear cell, is understudied. EACs are histologically and clinically distinct from other gynecological cancers due to their unique origin within endometriosis. The endometriotic microenvironment is uniquely hypoxic with high levels of iron due to recurrent menstrual cycling, and this iron-rich microenvironment has been linked to promoting carcinogenesis through iron-induced oxidative stress. However, the mechanism by which the endometriotic microenvironment contributes to EAC tumorigenesis and how this compares with endometrial cancer is unknown. Most of our current knowledge of EACs is built on either epidemiologic analyses or correlative studies. Additionally, most studies of the endometriotic microenvironment primarily focus on the epithelial component while the role of the stroma has been largely unexplored. Mesenchymal stem cells (MSC) are a critical component of the stromal microenvironment. Recently, we identified a key role of endometriosis derived MSCs (enMSCs) in altering ovarian clear cell carcinoma iron regulation. Interestingly, enMSCs resemble the primary endometrium derived MSCs, which suggested their role in endometrial cancer. This stromal subset is characterized by the loss of surface CD10 expression. It is known that cancer cells, particularly clear cell carcinoma (CCC), have a unique requirement for high levels of iron. We hypothesize that CD10 negative enMSCs promote growth of EAC and endometrial cancer through iron regulation. MSCs were isolated from primary human benign endometriosis, benign endometrium, or endometrial cancer. Flow cytometry was used to measure surface CD10 expression. We investigated the role of CD10 negative enMSCs on CCC iron regulation. Our results showed that CD10 negative enMSCs promote CCC growth by exporting iron through the upregulation of Hephaestin (HEPH) and Ferroportin (FPO) which then led to increase labile iron pool (LIP) in CCC cells. However, increasing the LIP does not occur with iron supplementation alone, this indicates the critical role of CD10 negative enMSCs in regulating iron handling in CCC cells. Additionally, our data showed that CD10 negative enMSCs alter the balance of Ferritin L and Ferritin H- the main iron storage proteins- in CCC cells. Mechanistically, our preliminary data showed that CD10 negative enMSCs directly donate Ferritin L into CCC cells. Further, CD10 negative enMSCs enhance Ferritin H degradation through the upregulation of ferritinophagy in CCC cells. In conclusion, our results indicate there is a sub-population of enMSCs, marked by the loss of CD10 expression, that enhances EAC and endometrial cancer cell growth through iron regulation. This highlights the existence of a tumor-promoting stromal cell within both the endometrium and endometriosis which can be capitalized on as an “Achilles' heel” to uncover novel treatment targets for EAC and endometrial cancer. Citation Format: Huda I. Atiya, Lan G. Coffman. Role of stromal CD10 expression in progression of endometrial and endometriosis-associated cancers [abstract]. In: Proceedings of the AACR Special Conference on Endometrial Cancer: Transforming Care through Science; 2023 Nov 16-18; Boston, Massachusetts. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(5_Suppl):Abstract nr A014.

Abstract TMP114: The Role of Iron Mediated Oxidative Stress and Lipid Peroxidation in the Development of Intracranial Aneurysm Rupture

Introduction: Iron is an essential element for vascular wall maintenance. However, iron deposition in the vascular wall may cause oxidative stress, which can attack DNA, proteins, and lipid membranes via the Fenton/Haber-Weiss reaction. Iron-induced oxidative stress triggers lipid oxidation, inflammation, endothelial cell activation and intracranial aneurysmal formation, growth, and rupture. Subarachnoid hemorrhage from intracranial aneurysm rupture results in significant morbidity and mortality. This study used a mouse model of intracranial aneurysm to evaluate the effect of dietary iron restriction on aneurysm formation and rupture. Methods: Intracranial aneurysms were induced using deoxycorticosterone acetate-salt-induced hypertension and a single injection of elastase into the cerebrospinal fluid of the basal cistern. Mice were fed an iron-restricted diet or a normal diet. Aneurysm rupture was detected by neurological symptoms, while the presence of intracranial aneurysm with subarachnoid hemorrhage was confirmed by post-mortem examination. Results: The aneurysmal rupture rate was significantly lower in iron-restricted diet mice (37%) compared with normal diet mice (76%; p < 0.05). Serum oxidative stress, iron accumulation, macrophage infiltration, and 8-hydroxy-2′-deoxyguanosine in the vascular wall were lower in iron-restricted diet mice ( p < 0.01). The areas of iron positivity were similar to the areas of CD68 positivity and 8-hydroxy-2′-deoxyguanosine in both normal diet and iron-restricted diet mice aneurysms. Conclusions: Compared with a normal diet, an iron-restricted diet reduced the incidence of intracranial aneurysmal rupture in mice via inhibition of iron accumulation in the aneurysmal wall. Iron may be a potential therapeutic target to prevent intracranial aneurysm rupture. Long-term iron restriction may be required to affect aneurysm formationrupture.

The Effect of Oral Iron Chelator Deferiprone on Iron Overload and Oxidative Stress in Patients with Myelodysplastic Syndromes: A Study by the Israeli MDS Working Group

Background: Most patients with lower risk myelodysplastic neoplasms or syndromes (MDSs) become RBC transfusion-dependent, resulting in iron overload, which is associated with an increased oxidative stress state. Iron-chelation therapy is applied to attenuate the toxic effects of this state. Deferiprone (DFP) is an oral iron chelator, which is not commonly used in this patient population, due to safety concerns, mainly agranulocytosis. The purpose of this study was to assess the effect of DFP, on oxidative stress parameters in iron-overloaded RBC transfusion-dependent patients with lower risk MDSs. Methods: Adult lower risk MDS patients with a cumulative transfusion burden of >20 red blood cell units and evidence of iron overload (serum ferritin >1,000 ng/mL) were included in this study. DFP was administered (100 mg/kg/day) for 4 months. Blood samples for oxidative stress parameters and iron overload parameters were done at baseline and monthly: reactive oxygen species (ROS), phosphatidylserine, reduced glutathione, membrane lipid peroxidation, serum ferritin, and cellular labile iron pool. The primary efficacy variable was ROS. Tolerability and side effects were recorded as well. A paired t test was applied for statistical analyses. Results: Eighteen patients were treated with DFP. ROS significantly decreased in all cell lineages: median decrease of 58.6% in RBC, 33.3% in PMN, and 39.8% in platelets (p p p Conclusions: Herein, we showed preliminary evidence that DFP decreases iron-induced oxidative stress in MDS patients with a good tolerability profile (albeit a short follow-up period). No cases of severe neutropenia or agranulocytosis were reported. The future challenge is to prove that reduction in iron toxicity will eventually be translated into a clinically meaningful improvement.

Sonneratia apetala (Buch.-Ham.) Fruit Extracts Ameliorate Iron Overload and Iron-Induced Oxidative Stress in Mice.

Iron overload results in oxidative damage to various biomolecules including DNA, proteins and lipids which ultimately leads to cell death. The Sonneratia apetala fruit contains a high content of antioxidants and displays several bioactive properties. Therefore, the powder of the S. apetala fruit was successively fractionated into n-hexane (Hex), chloroform (Chl), and methanol (Met) fractions to evaluate their efficiency in ameliorating iron overload. In vitro, a colorimetric method was used to assess the Fe-chelating activity of the fractions using ferrozine. The fractions were also used in vivo to examine their efficacy in ameliorating iron overload and iron-induced oxidative stress in mice induced by intraperitoneal injection of ferric carboxymaltose at 100 mg/kg body weight (bw). Among the fractions, Met showed the highest Fe-chelation ability with an inhibitory concentration 50 of 165 μg/mL followed by Hex (270 μg/mL), and Chl (418 μg/mL). In vivo, the results showed a significantly (P<0.05) lower iron profile (iron and ferritin concentrations in serum and liver tissue and total iron-binding capacity of serum) in the Met and the Hex treated mice groups than in the iron-overloaded group. Met at 1,000 μg/kg bw completely ameliorated iron overload in the blood and the liver tissue of mice. At this concentration, Met also prevented iron-induced oxidative stress in the liver tissue of iron-overloaded mice by restoring reducing power, total antioxidant capacity, and total protein. Thus, the S. apetala fruit, especially its Met fraction can be used in treating iron overload and associated toxicity.

Kaempferol stimulation of autophagy regulates the ferroptosis under the oxidative stress as mediated with AMP-activated protein kinase

Recent studies have highlighted the positive effects of Kaempferol (KP), including its anti-inflammatory and antioxidant properties. However, its impact on oxidative damage induced by heavy metals and pro-inflammatory mediators, such as arachidonic acid (AA), has not yet been identified. Our objective was to specifically evaluate liver damage due to AA + iron-induced oxidative stress, both in vitro and in vivo. In HepG2 cells, KP activated the AMP-activated protein kinase (AMPK), suggesting a hepatoprotective effect through AMPK inhibition, as assessed by immunoblot and FACS analysis (EC50 = 10 μM). KP also stimulated autophagy, a degradation process that eliminates aged, damaged, and unnecessary components, via mTOR inhibition and ULK1 phosphorylation. This activation was further validated by the upregulation of autophagy-related genes (ATG5) and Beclin-1, along with the conversion of LC3BI to LC3BII. Ferroptosis, a non-apoptotic type of cell death characterized by oxidative stress from the production of reactive oxygen species (ROS) and excessive iron accumulation, was linked to the activation of autophagy, as confirmed through the protein expression of deferoxamine (DFO) and ferrostatin-1 (Fer-1), the representative ferroptosis inhibitors (positive controls). In mice, oral administration of KP demonstrated protective effects against CCl4-induced hepatotoxicity. In conclusion, KP provides hepatoprotective effects against oxidative stress induced by AA + iron treatment in vitro and CCl4 treatment in vivo.

Antioxidant Effects of Argan Oil and Olive Oil against Iron-Induced Oxidative Stress: In Vivo and In Vitro Approaches.

Recently, the study of the protective powers of medicinal plants has become the focus of several studies. Attention has been focused on the identification of new molecules with antioxidant and chelating properties to counter reactive oxygen species (ROS) involved as key elements in several pathologies. Considerable attention is given to argan oil (AO) and olive oil (OO) due to their particular composition and preventive properties. Our study aimed to determine the content of AO and OO on phenolic compounds, chlorophylls, and carotenoid pigments and their antioxidant potential by FRAP and DPPH tests. Thus, several metallic elements can induce oxidative stress, as a consequence of the formation of ROS. Iron is one of these metal ions, which participates in the generation of free radicals, especially OH from H2O2 via the Fenton reaction, initiating oxidative stress. To study the antioxidant potential of AO and OO, we evaluated their preventives effects against oxidative stress induced by ferrous sulfate (FeSO4) in the protozoan Tetrahymena pyriformis and mice. Then, we evaluated the activities of the enzymatic (superoxide dismutase (SOD), glutathione peroxidase (GPx)) and metabolite markers (lipid peroxidation (MDA) and glutathione (GSH)) of the antioxidant balance. The results of the antioxidant compounds show that both oils contain phenolic compounds and pigments. Moreover, AO and OO exhibit antioxidant potential across FRAP and DPPH assays. On the other hand, the results in Tetrahymena pyriformis and mice show a variation in the level of iron-changed SOD and GPx activities and MDA and GSH levels. By contrast, treating Tetrahymena pyriformis and mice with argan and olive oils shows significant prevention in the SOD and GPx activities. These results reveal that the iron-changed ROS imbalance can be counteracted by AO and OO, which is probably related to their composition, especially their high content of polyphenols, sterols, and tocopherols, which is underlined by their antioxidant activities.

Ferulic acid protects HepG2 cells and mouse liver from iron-induced damage

Liver as iron storage organ is particularly susceptible to oxidative stress-induced injury from excess iron. Thus, antioxidant therapies are often used to reverse oxidative damage and protect cells and tissues. This study investigated the protective effects of phenolic acids; ferulic acid (FA) and its metabolite, ferulic acid 4-O-sulfate disodium salt (FAS) against oxidative stress under iron overload conditions in mouse and HepG2 cells. Cells were exposed to FA or FAS and then treated with iron-induced oxidative stress complex of 50 μmol/L FAC and 20 μmol/L of 8-hydroxyquinoline 8HQ (8HQ-FAC). Iron dextran was injected intraperitoneally on alternate days for 10 days to induce the iron overload condition in BALB/c mice. The study revealed that the phenolic acids were protective against ROS production, lipid peroxidation and antioxidant depletion in HepG2 cells and liver tissues of BALB/c mice during iron-induced oxidative stress. The protective function of phenolic acids was achieved by the transcriptional activation of nuclear factor erythroid-2-related factor 2 (Nrf2) to regulate antioxidant genes. In conclusion, the study provides evidence that FA has the potential as a therapeutic agent against iron-related diseases such as T2D.

Effect of iron on rat serum melatonin levels under different light/dark cycle patterns

Exposure to constant light or darkness for long periods has diverse effects on circadian physiology. Iron (Fe) overloading promotes oxidative stress and causes alterations in cellular structure and function in animals and humans. The aim of this study is to evaluate the interactions among serum melatonin (ML), photoperiod manipulation, and Fe overloading in rats. The results showed that constant darkness exposure for 15 days significantly increased serum ML levels (up to 22%) while the constant light exposure failed to reduce the serum ML level compared to the normal light/dark cycle treated rats. The lost serum ML level usually from the pineal gland under the long term of constant light exposure may be compensated by ML generated by other organs which adapted to the situation. Also, Fe overloading decreased ML production due to this molecule being consumed to scavenge the free radicals induced by the Fe overloading. In addition, we observed interactions among constant light or darkness exposure, Fe overloading and serum ML level. Overall, our results support the hypothesis of ML as scavenging molecule; it may be an effective therapeutic tool in iron-induced oxidative stress.

Heme-deficient primitive red blood cells induce HSPC ferroptosis by altering iron homeostasis during zebrafish embryogenesis.

The crosstalk between hematopoietic lineages is important for developmental hematopoiesis. However, the role of primitive red blood cells (RBCs) in the formation of definitive hematopoietic stem and progenitor cells (HSPCs) is largely unknown. Primitive RBC deficiencies in mammals always lead to early embryonic lethality, but zebrafish lines with RBC deficiencies can survive to larval stage. By taking advantage of a zebrafish model, we find that the survival of nascent HSPCs is impaired in alas2- or alad-deficient embryos with aberrant heme biosynthesis in RBCs. Heme-deficient primitive RBCs induce ferroptosis of HSPCs through the disruption of iron homeostasis. Mechanistically, heme-deficient primitive RBCs cause blood iron-overload via Slc40a1, and an HSPC iron sensor, Tfr1b, mediates excessive iron absorption. Thus, iron-induced oxidative stress stimulates the lipid peroxidation, which directly leads to HSPC ferroptosis. Anti-ferroptotic treatments efficiently reverse HSPC defects in alas2 or alad mutants. HSPC transplantation assay reveals that the attenuated erythroid reconstitution efficiency may result from the ferroptosis of erythrocyte-biased HSPCs. Together, these results illustrate that heme-deficient primitive RBCs are detrimental to HSPC production and may provide potential implications for iron dysregulation-induced hematological malignancies.

Effect of diabetic macular oedema on serum iron status indicators

ABSTRACT Clinical relevance The role of subclinical inflammation in the pathophysiology of diabetic macular oedema (DME), which is known to be quite complex, is of much interest. Serum ferritin level, which is an indicator of body iron stores, is both an inflammatory marker for various neurodegenerative diseases and an important indicator in the evaluation of iron-induced oxidative stress. Background Iron metabolism indicators play a role in the formation and development of diabetic retinopathy, which is known to be associated with subclinical inflammation, and may also play a role in the pathogenesis of DME. The aim of this study was to investigate the role of serum iron metabolism markers in the pathogenesis of DME. Materials and methods The files of all nonproliferative diabetic retinopathy (NPDR) patients who were scheduled for the first intravitreal injection for DME in the eye clinic between January 2019 and January 2020 were reviewed retrospectively. By examining the files of all diabetes mellitus patients who attended the outpatient eye clinic on the same dates, those without retinopathy and those with NPDR but not DME were recorded. All results, including a comprehensive ophthalmological examination, laboratory data of fasting blood tests, and an internal medicine outpatient examination were collected for analysis. Results Of the 157 participants, 44 were NPDR patients with oedema, 50 were NPDR patients without oedema, and 63 were patients without retinopathy. There was a significant difference between the groups in respect of creatinine, high-density lipoprotein, mean corpuscular volume, serum iron and ferritin, total iron binding capacity and transferrin saturation (p < 0.050). Ferritin values were found to be significantly higher in patients with macular oedema. Other iron status markers were found to be significantly lower (p < 0.050). Conclusion Evaluation of serum iron status indicators in the routine follow-up of diabetic patients may be of diagnostic and/or prognostic benefit in terms of DME.

The expression of ceruloplasmin in astrocytes is essential for postnatal myelination and myelin maintenance in the adult brain.

Ceruloplasmin (Cp) is a ferroxidase enzyme that is essential for cell iron efflux. The absence of this protein in humans and rodents produces progressive neurodegeneration with brain iron accumulation. Astrocytes express high levels of Cp and iron efflux from these cells has been shown to be central for oligodendrocyte maturation and myelination. To explore the role of astrocytic Cp in brain development and aging we generated a specific conditional KO mouse for Cp in astrocytes (Cp cKO). Deletion of Cp in astrocytes during the first postnatal week induced hypomyelination and a significant delay in oligodendrocyte maturation. This abnormal myelin synthesis was exacerbated throughout the first two postnatal months and accompanied by a reduction in oligodendrocyte iron content, as well as an increase in brain oxidative stress. In contrast to young animals, deletion of astrocytic Cp at 8 months of age engendered iron accumulation in several brain areas and neurodegeneration in cortical regions. Aged Cp cKO mice also showed myelin loss and oxidative stress in oligodendrocytes and neurons, and at 18 months of age, developed abnormal behavioral profiles, including deficits in locomotion and short-term memory. In summary, our results demonstrate that iron efflux-mediated by astrocytic Cp-is essential for both early oligodendrocyte maturation and myelin integrity in the mature brain. Additionally, our data suggest that astrocytic Cp activity is central to prevent iron accumulation and iron-induced oxidative stress in the aging CNS.

Quantitative omics analyses of NCOA4 deficiency reveal an integral role of ferritinophagy in iron homeostasis of hippocampal neuronal HT22 cells.

Neurons require iron to support their metabolism, growth, and differentiation, but are also susceptible to iron-induced oxidative stress and cytotoxicity. Ferritin, a cytosolic iron storage unit, mediates cellular adaptation to fluctuations in iron delivery. NCOA4 has been characterized as a selective autophagic cargo receptor facilitating the mobilization of intracellular iron from ferritin. This process named ferritinophagy results in the degradation of ferritin and the consequent release of iron into the cytosol. Here we demonstrate that NCOA4 is important for the adaptation of the HT22 mouse hippocampal neuronal cell line to cellular iron restriction. Additionally, we determined the pathophysiological implications of impaired ferritinophagy via functional analysis of the omics profile of HT22 cells deficient in NCOA4. NCOA4 silencing impaired ferritin turnover and was cytotoxic when cells were restricted of iron. Quantitative proteomics identified IRP2 accumulation among the most prominent protein responses produced by NCOA4 depletion in HT22 cells, which is indicative of functional iron deficiency. Additionally, proteins of apoptotic signaling pathway were enriched by those responsive to NCOA4 deficiency. Transcriptome profiles of NCOA4 depletion revealed neuronal cell death, differentiation of neurons, and development of neurons as potential diseases and bio functions affected by impaired ferritinophagy, particularly, when iron was restricted. These findings identify an integral role of NCOA4-mediated ferritinophagy in the maintenance of iron homeostasis by HT22 cells, and its potential implications in controlling genetic pathways of neurodevelopment and neurodegenerative diseases.

Baicalein Attenuates Brain Iron Accumulation through Protecting Aconitase 1 from Oxidative Stress in Rotenone-Induced Parkinson's Disease in Rats.

Aconitase 1 (ACO1) links oxidative stress and iron accumulation in Parkinson's disease (PD). ACO1 loses its aconitase activity and turns into iron regulatory protein 1 (IRP1) upon oxidative stress. IRP1 plays an important role in the accumulation of intracellular iron. Baicalein is a flavonoid isolated from the roots of Scutellaria baicalensis. The present results show that baicalein could bind to ACO1 and protect its isoform from the oxidative stress induced by reactive oxygen species (ROS) and reactive nitrogen species (RNS). Furthermore, baicalein promoted aconitase activity and inhibited IRP1 activation in rotenone-induced PD models. Additionally, baicalein decreased the hydroxyl radicals generated by iron. In conclusion, baicalein attenuated iron accumulation and iron-induced oxidative stress in the brain of PD rats by protecting ACO1.

Metagenomic Insights into the Adaptive Responses of the Microbiome of a Spent Engine Oil-Perturbed Agricultural Soil to Iron Stress

In hydrocarbon-impacted matrices, accessibility to iron, an essential micronutrient poses a significant challenge to microorganisms due to its complexation with hydrocarbon pollutants. This necessitates the elicitation of diverse adaptive responses to counteract the iron stress and achieve cellular iron homeostasis. In this study, putative genes responsible for iron acquisition, iron regulation, and iron storage in agricultural soil (1S) and agricultural soil amended with spent engine oil (AB1) were evaluated through functional annotation of their open reading frames (ORFs). Functional annotation was done using KEGG KofamKOALA and BacMet. Annotation revealed 110 genes in AB1 of which 96 (87.3%) were annotated for iron acquisition. The iron acquisition genes were responsible for Fe2+/Fe3+ transport and efflux, heme transport, vitamin B12/cobalamin transport, siderophore transport and biosynthesis. In IS metagenome, 28 genes were detected, of which 20 (71.4%) were annotated for iron acquisition. More genes involved in iron regulation and oxidative stress protection were detected in AB1 metagenome while significant differences observed in the iron metabolism genes recovered from 1S and AB1 metagenomes were statistically validated (p < 0.05). The study revealed that spent engine oil contamination of the agricultural soil imposed significant iron stress on the AB1 microbiome necessitating the expression of several genes encoding high affinity iron uptake systems (siderophores, ABC iron transporters), global iron regulators, and iron-induced oxidative stress protection proteins.

Neuroprotective Effects of Transferrin in Experimental Glaucoma Models.

Iron is essential for retinal metabolism, but an excess of ferrous iron causes oxidative stress. In glaucomatous eyes, retinal ganglion cell (RGC) death has been associated with dysregulation of iron homeostasis. Transferrin (TF) is an endogenous iron transporter that controls ocular iron levels. Intraocular administration of TF is neuroprotective in various models of retinal degeneration, preventing iron overload and reducing iron-induced oxidative stress. Herein, we assessed the protective effects of TF on RGC survival, using ex vivo rat retinal explants exposed to iron, NMDA-induced excitotoxicity, or CoCl2-induced hypoxia, and an in vivo rat model of ocular hypertension (OHT). TF significantly preserved RGCs against FeSO4-induced toxicity, NMDA-induced excitotoxicity, and CoCl2-induced hypoxia. TF protected RGCs from apoptosis, ferroptosis, and necrosis. In OHT rats, TF reduced RGC loss by about 70% compared to vehicle-treated animals and preserved about 47% of the axons. Finally, increased iron staining was shown in the retina of a glaucoma patient's eye as compared to non-glaucomatous eyes. These results indicate that TF can interfere with different cell-death mechanisms involved in glaucoma pathogenesis and demonstrate the ability of TF to protect RGCs exposed to elevated IOP. Altogether, these results suggest that TF is a promising treatment against glaucoma neuropathy.

Non-heme iron overload impairs monocyte to macrophage differentiation via mitochondrial oxidative stress.

Iron is a key element for systemic oxygen delivery and cellular energy metabolism. Thus regulation of systemic and local iron metabolism is key for maintaining energy homeostasis. Significant changes in iron levels due to malnutrition or hemorrhage, have been associated with several diseases such as hemochromatosis, liver cirrhosis and COPD. Macrophages are key cells in regulating iron levels in tissues as they sequester excess iron. How iron overload affects macrophage differentiation and function remains a subject of debate. Here we used an in vitro model of monocyte-to-macrophage differentiation to study the effect of iron overload on macrophage function. We found that providing excess iron as soluble ferric ammonium citrate (FAC) rather than as heme-iron complexes derived from stressed red blood cells (sRBC) interferes with macrophage differentiation and phagocytosis. Impaired macrophage differentiation coincided with increased expression of oxidative stress-related genes. Addition of FAC also led to increased levels of cellular and mitochondrial reactive oxygen species (ROS) and interfered with mitochondrial function and ATP generation. The effects of iron overload were reproduced by the mitochondrial ROS-inducer rotenone while treatment with the ROS-scavenger N-Acetylcysteine partially reversed FAC-induced effects. Finally, we found that iron-induced oxidative stress interfered with upregulation of M-CSFR and MAFB, two crucial determinants of macrophage differentiation and function. In summary, our findings suggest that high levels of non-heme iron interfere with macrophage differentiation by inducing mitochondrial oxidative stress. These findings might be important to consider in the context of diseases like chronic obstructive pulmonary disease (COPD) where both iron overload and defective macrophage function have been suggested to play a role in disease pathogenesis.

Harpagophytum procumbens Inhibits Iron Overload-Induced Oxidative Stress through Activation of Nrf2 Signaling in a Rat Model of Lumbar Spinal Stenosis.

Lumbar spinal stenosis (LSS) is a common degenerative spinal condition in older individuals that causes impaired walking and other disabilities due to severe lower back and leg pain. Ligamentum flavum hypertrophy is a major LSS cause that may result from oxidative stress caused by degenerative cascades, including imbalanced iron homeostasis that leads to excessive reactive oxygen species production. We investigated the effects of Harpagophytum procumbens (HP) on iron-induced oxidative stress associated with LSS pathophysiology. Primary spinal cord neuron cultures were incubated in FeSO4-containing medium, followed by addition of 50, 100, or 200 μg/mL HP. Cell viability was assessed by CCK-8 and live/dead cell assays and by propidium iodide-live imaging. In an in vivo rat model of LSS, HP were administered at 100, 200, and 400 mg/kg, and disease progression was monitored for up to 3 weeks. We investigated the in vitro and in vivo effects of HP on iron-induced neurotoxicity by immunochemistry, real-time PCR, and flow cytometry. HP exerted neuroprotective effects and enhanced neurite outgrowths of iron-injured rat primary spinal cord neurons in vitro. HP treatment significantly reduced necrotic cell death and improved cells' antioxidative capacity via the NRF2 signaling pathway in iron-treated neurons. At 1 week after HP administration in LSS rats, the inflammatory response and oxidative stress markers were substantially reduced through regulation of excess iron accumulation. Iron that accumulated in the spinal cord underneath the implanted silicone was also regulated by HP administration via NRF2 signaling pathway activation. HP-treated LSS rats showed gradually reduced mechanical allodynia and amelioration of impaired behavior for 3 weeks. We demonstrated that HP administration can maintain iron homeostasis within neurons via activation of NRF2 signaling and can consequently facilitate functional recovery by regulating iron-induced oxidative stress. This fundamentally new strategy holds promise for LSS treatment.