Iron promotes neurological function recovery in mice with ischemic stroke through endogenous repair mechanisms

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

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

Ferroptosis inhibitors: past, present and future

Ferroptosis is a non-apoptotic mode of programmed cell death characterized by iron dependence and lipid peroxidation. Since the ferroptosis was proposed, researchers have revealed the mechanisms of its formation and continue to explore effective inhibitors of ferroptosis in disease. Recent studies have shown a correlation between ferroptosis and the pathological mechanisms of neurodegenerative diseases, as well as diseases involving tissue or organ damage. Acting on ferroptosis-related targets may provide new strategies for the treatment of ferroptosis-mediated diseases. This article specifically describes the metabolic pathways of ferroptosis and summarizes the reported mechanisms of action of natural and synthetic small molecule inhibitors of ferroptosis and their efficacy in disease. The paper also describes ferroptosis treatments such as gene therapy, cell therapy, and nanotechnology, and summarises the challenges encountered in the clinical translation of ferroptosis inhibitors. Finally, the relationship between ferroptosis and other modes of cell death is discussed, hopefully paving the way for future drug design and discovery.

Innovations in Breaking Barriers: Liposomes as Near-Perfect Drug Carriers in Ischemic Stroke Therapy

Liposomes, noted for their tunable particle size, surface customization, and varied drug delivery capacities, are increasingly acknowledged in therapeutic applications. These vesicles exhibit surface flexibility, enabling the incorporation of targeting moieties or peptides to achieve specific targeting and avoid lysosomal entrapment. Internally, their adaptable architecture permits the inclusion of a broad spectrum of drugs, contingent on their solubility characteristics. This study thoroughly reviews liposome fabrication, surface modifications, and drug release mechanisms post-systemic administration, with a particular emphasis on drugs crossing the blood-brain barrier (BBB) to address lesions. Additionally, the review delves into recent developments in the use of liposomes in ischemic stroke models, offering a comparative evaluation with other nanocarriers like exosomes and nano-micelles, thereby facilitating their clinical advancement.

Piezo1 Knockout Improves Post-Stroke Cognitive Dysfunction by Inhibiting the Interleukin-6 (IL-6)/Glutathione Peroxidase 4 (GPX4) Pathway

Background

Cerebral infarction often results in post-stroke cognitive impairment, which impairs the quality of life and causes long-term disability. Astrocytes, the most abundant glial cells in the central nervous system, have a crucial role in cerebral ischemia and neuroinflammation. We explored the possible advantages of interleukin-6 (IL-6), a powerful pro-inflammatory cytokine produced by astrocytes, for post-stroke cognitive function.

Methods

Mendelian randomization was applied to analyze the GWAS database of stroke patients, obtaining a causal relationship between IL-6 and stroke. Further validation of this relationship and its mechanisms was conducted. Using a mouse model of cerebral infarction, we demonstrated a significant increase in IL-6 expression in astrocytes surrounding the ischemic lesion. This protective effect of Piezo1 knockout was attributed to the downregulation of matrix metalloproteinases and upregulation of tight junction proteins, such as occludin and zonula occludens-1 (ZO-1).

Results

Two-step Mendelian randomization revealed that IL-6 exposure is a risk factor for stroke. Moreover, we conducted behavioral assessments and observed that Piezo1 knockout mice that received intranasal administration of astrocyte-derived IL-6 showed notable improvement in cognitive function compared to control mice. This enhancement was associated with reduced neuronal cell death and suppressed astrocyte activation, preserving ZO-1.

Conclusion

Our study shows that astrocyte-derived IL-6 causes cognitive decline after stroke by protecting the blood-brain barrier. This suggests that piezo1 knockout may reduce cognitive impairment after brain ischemia. Further research on the mechanisms and IL-6 delivery methods may lead to new therapies for post-stroke cognition.

A New Perspective in the Treatment of Ischemic Stroke: Ferroptosis

Ischemic stroke is a common neurological disease. Currently, there are no Food and Drug Administration-approved drugs that can maximize the improvement in ischemic stroke-induced nerve damage. Hence, treating ischemic stroke remains a clinical challenge. Ferroptosis has been increasingly studied in recent years, and it is closely related to the pathophysiological process of ischemic stroke. Iron overload, reactive oxygen species accumulation, lipid peroxidation, and glutamate accumulation associated with ferroptosis are all present in ischemic stroke. This article focuses on describing the relationship between ferroptosis and ischemic stroke and summarizes the relevant substances that ameliorate ischemic stroke-induced neurological damage by inhibiting ferroptosis. Finally, the problems in the treatment of ischemic stroke targeting ferroptosis are discussed, hoping to provide a new direction for its treatment.

Brain Iron Homeostasis and Mental Disorders

Iron plays an essential role in various physiological processes. A disruption in iron homeostasis can lead to severe consequences, including impaired neurodevelopment, neurodegenerative disorders, stroke, and cancer. Interestingly, the link between mental health disorders and iron homeostasis has not received significant attention. Therefore, our understanding of iron metabolism in the context of psychological diseases is incomplete. In this review, we aim to discuss the pathologies and potential mechanisms that relate to iron homeostasis in associated mental disorders. We propose the hypothesis that maintaining brain iron homeostasis can support neuronal physiological functions by impacting key enzymatic activities during neurotransmission, redox balance, and myelination. In conclusion, our review highlights the importance of investigating the relationship between trace element nutrition and the pathological process of mental disorders, focusing on iron. This nutritional perspective can offer valuable insights for the clinical treatment of mental disorders.

Intermittent hypoxia protects against hypoxic-ischemic brain damage by inducing functional angiogenesis

Ischemic stroke (IS) induces neurological damage due to cerebrovascular occlusion. Restoring blood perfusion to the ischemic brain area in a timely fashion is the most effective treatment strategy. Hypoxia is an effective way of restoring blood perfusion by improving cerebrovascular microcirculation, while the effect varies greatly depending on hypoxic mode. This study aimed to screen for the optimal hypoxic mode to improve cerebrovascular microcirculation and prevent IS. Here, we found that compared with continuous hypoxia (CH), intermittent hypoxia (IH) significantly improved cerebral blood flow and oxygen saturation in mice without causing neurological impairment. By analyzing cerebrovascular microcirculation from mice, we found that the IH mode (13%, 5*10) with 13% O2, 5 min interval, and 10 cycles per day significantly improved the cerebrovascular microcirculation by promoting angiogenesis without affecting the integrity of the blood-brain barrier. In addition, IH (13%, 5*10) treatment of distal middle cerebral artery occlusion (dMCAO) mice significantly alleviated neurological dysfunction and reduced cerebral infarct volume by improving cerebrovascular microcirculation. CH had none of these positive effects. In summary, our study screened for an appropriate intermittent hypoxic mode that could improve cerebrovascular microcirculation, laying a theoretical foundation for the prevention and treatment of IS in clinical practice.

Iron homeostasis imbalance and ferroptosis in brain diseases

Brain iron homeostasis is maintained through the normal function of blood-brain barrier and iron regulation at the systemic and cellular levels, which is fundamental to normal brain function. Excess iron can catalyze the generation of free radicals through Fenton reactions due to its dual redox state, thus causing oxidative stress. Numerous evidence has indicated brain diseases, especially stroke and neurodegenerative diseases, are closely related to the mechanism of iron homeostasis imbalance in the brain. For one thing, brain diseases promote brain iron accumulation. For another, iron accumulation amplifies damage to the nervous system and exacerbates patients' outcomes. In addition, iron accumulation triggers ferroptosis, a newly discovered iron-dependent type of programmed cell death, which is closely related to neurodegeneration and has received wide attention in recent years. In this context, we outline the mechanism of a normal brain iron metabolism and focus on the current mechanism of the iron homeostasis imbalance in stroke, Alzheimer's disease, and Parkinson's disease. Meanwhile, we also discuss the mechanism of ferroptosis and simultaneously enumerate the newly discovered drugs for iron chelators and ferroptosis inhibitors.

Developing hyaluronic acid-proline-ferric ion cross-linked film for efficient wound healing application

A novel cross-linked film dressing that can accelerate wound healing and guard against bacterial infection was presented in this work. The hyaluronic acid-proline-ferric ion (HA-Pro-Fe³⁺) film was successfully prepared by physically cross-linking method, which the carboxyl groups of the HA and Pro molecules should be in coordination with Fe³⁺. The HA-Pro-Fe³⁺ cross-linked film showed three-dimensional porous structure, appropriate water vapor permeability and swelling property, favorable cytocompatibility and hemocompatibility, antibacterial and antioxidative capability. The results of rat skin wound healing confirmed that HA-Pro-Fe³⁺ film could accelerate epithelial regeneration and collagen deposition, promote angiogenesis and significantly improve skin wound healing. Elisa analysis indicated that HA-Pro-Fe³⁺ material could down-regulate the expression of IL-6 and TNF-α, and up-regulate the level of TGF-β₁ and VEGF. Given its biocompatibility, antibacterial ability, promotion of cell proliferation and angiogenesis, the wide application of HA-Pro-Fe³⁺ cross-linked film in wound repair would be anticipated.

Brain Iron Metabolism, Redox Balance and Neurological Diseases

The incidence of neurological diseases, such as Parkinson's disease, Alzheimer's disease and stroke, is increasing. An increasing number of studies have correlated these diseases with brain iron overload and the resulting oxidative damage. Brain iron deficiency has also been closely linked to neurodevelopment. These neurological disorders seriously affect the physical and mental health of patients and bring heavy economic burdens to families and society. Therefore, it is important to maintain brain iron homeostasis and to understand the mechanism of brain iron disorders affecting reactive oxygen species (ROS) balance, resulting in neural damage, cell death and, ultimately, leading to the development of disease. Evidence has shown that many therapies targeting brain iron and ROS imbalances have good preventive and therapeutic effects on neurological diseases. This review highlights the molecular mechanisms, pathogenesis and treatment strategies of brain iron metabolism disorders in neurological diseases.

Baicalin facilitates remyelination and suppresses neuroinflammation in rats with chronic cerebral hypoperfusion by activating Wnt/β-catenin and inhibiting NF-κB signaling

One main factor contributing to the cognitive loss in vascular dementia (VD) is white matter lesions (WMLs) carried on by chronic cerebral hypoperfusion (CCH). A secondary neuroinflammatory response to CCH accelerates the loss and limits the regeneration of oligodendrocytes, leading to progressive demyelination and insufficient remyelination in the white matter. Thus, promoting remyelination and inhibiting neuroinflammation may be an ideal therapeutic strategy. Baicalin (BAI) is known to exhibit protective effects against various inflammatory and demyelinating diseases. However, whether BAI has neuroprotective effects against CCH has not been investigated. To determine whether BAI inhibits CCH-induced demyelination and neuroinflammation, we established a model of CCH in rats by occluding the two common carotid arteries bilaterally. Our results revealed that BAI could remarkably ameliorate cognitive impairment and mitigate CA1 pyramidal neuron damage and myelin loss. BAI exhibited enhancement of remyelination by increasing the expression of myelin basic protein (MBP) and oligodendrocyte transcription factor 2 (Olig2), inhibiting the loss of oligodendrocytes and promoting oligodendrocyte regeneration in the corpus callosum of CCH rats. Furthermore, BAI modified microglia polarization to the anti-inflammatory phenotype and inhibited the release of pro-inflammatory cytokines. Mechanistically, BAI treatment significantly induced phosphorylation of glycogen synthase kinase 3β (GSK3β), enhanced the expression of β-catenin and its nuclear translocation. Simultaneously, BAI reduced the expression of nuclear NF-κB. Collectively, our results suggest that BAI ameliorates cognitive impairment in CCH-induced VD rats through its pro-remyelination and anti-inflammatory capacities, possibly by activating the Wnt/β-catenin and suppressing the NF-κB signaling.

Cdh5-mediated Fpn1 deletion exerts neuroprotective effects during the acute phase and inhibitory effects during the recovery phase of ischemic stroke

Ischemic stroke is associated with high mortality and morbidity rates worldwide. However, the molecular mechanisms underlying the neuronal damage incurred by stroke victims remain unclear. It has previously been reported that ischemic stroke can induce an increase in the levels of brain iron, which is an important factor of in the associated brain damage. Ferroportin 1 (FPN1), the only known cellular iron export protein, is found in brain microvascular endothelial cells (BMVECs) at the blood-brain barrier, and is considered the gateway for entry of plasma iron into the central nervous system. Despite the connection of brain iron to neuronal damage, the role of BMVECs FPN1 in ischemic stroke remains unexplored. Herein, we conditionally deleted Fpn1 in mouse endothelial cells (ECs), using VE-cadherin-Cre transgenic mice, and explored the impact on brain iron homeostasis after stroke. Our data demonstrated that Fpn1 knockout in ECs decreased the brain iron levels in mice, attenuated the oxidative stress and inflammatory responses after stroke, and inhibited both ferroptosis and apoptosis, ultimately alleviating neurological impairment and decreasing cerebral infarct volume during the acute phase of ischemic stroke. By contrast, we found that Fpn1 knockout in ECs delayed the recovery of neurological function in mice following ischemic stroke. We also found that ECs Fpn1 knockout decreased the brain iron levels after stroke, exacerbated glial cell proliferation, and inhibited neuronal development, indicating that the diminished brain iron levels hindered the repair of neural injury in mice. In conclusion, our findings reveal a dual consequence of FPN1 deficiency in ECs in the development of ischemic stroke. More specifically, iron deficiency initially exerts a neuroprotective effect during the acute phase of ischemic stroke but inhibits recovery during the later stages. Our findings are important to the development of iron- or FPN1-targeting therapeutics for the treatment of ischemic stroke.