Therapeutic targeting of oxygen-sensing prolyl hydroxylases abrogates ATF4-dependent neuronal death and improves outcomes after brain hemorrhage in several rodent models

DMT1 ubiquitination by Nedd4 protects against ferroptosis after intracerebral hemorrhage

OBJECTIVE

Neuronal precursor cells expressed developmentally down-regulated 4 (Nedd4) are believed to play a critical role in promoting the degradation of substrate proteins and are involved in numerous biological processes. However, the role of Nedd4 in intracerebral hemorrhage (ICH) remains unknown. This study aims to investigate the regulatory role of Nedd4 in the ICH model.

METHODS

Male C57BL/6J mice were induced with ICH. Subsequently, the levels of glutathione peroxidase 4 (GPX4), malondialdehyde (MDA) concentration, iron content, mitochondrial morphology, as well as the expression of divalent metal transporter 1 (DMT1) and Nedd4 were assessed after ICH. Furthermore, the impact of Nedd4 overexpression was evaluated through analyses of hematoma area, ferroptosis, and neurobehavioral function. The mechanism underlying Nedd4-mediated degradation of DMT1 was elecidated using immunoprecipitation (IP) after ICH.

RESULTS

Upon ICH, the level of DMT1 in the brain increased, but decreased when Nedd4 was overexpressed using Lentivirus, suggesting a negative correlation between Nedd4 and DMT1. Additionally, the degradation of DMT1 was inhibited after ICH. Furthermore, it was found that Nedd4 can interact with and ubiquitinate DMT1 at lysine residues 6, 69, and 277, facilitating the degradation of DMT1. Functional analysis indicated that overexpression of Nedd4 can alleviate ferroptosis and promote recovery following ICH.

CONCLUSION

The results demonstrated that ferroptosis occurs via the Nedd4/DMT1 pathway during ICH, suggesting it potential as a valuable target to inhibit ferroptosis for the treatment of ICH.

Pivotal Role of GSTO2 in Ferroptotic Neuronal Injury After Intracerebral Hemorrhage

Previous research has found that an adaptive response to ferroptosis involving glutathione peroxidase 4 (GPX4) is triggered after intracerebral hemorrhage. However, little is known about the mechanisms underlying adaptive responses to ferroptosis. To explore the mechanisms underlying adaptive responses to ferroptosis after intracerebral hemorrhage, we used hemin-treated HT22 cells to mimic brain injury after hemorrhagic stroke in vitro to evaluate the antioxidant enzymes and performed bioinformatics analysis based on the mRNA sequencing data. Further, we determined the expression of GSTO2 in hemin-treated hippocampal neurons and in a mouse model of hippocampus-intracerebral hemorrhage (h-ICH) by using Western blot. After hemin treatment, the antioxidant enzymes GPX4, Nrf2, and glutathione (GSH) were upregulated, suggesting that an adaptive response to ferroptosis was triggered. Furthermore, we performed mRNA sequencing to explore the underlying mechanism, and the results showed that 2234 genes were differentially expressed. Among these, ten genes related to ferroptosis (Acsl1, Ftl1, Gclc, Gclm, Hmox1, Map1lc3b, Slc7a11, Slc40a1, Tfrc, and Slc39a14) were altered after hemin treatment. In addition, analysis of the data retrieved from the GO database for the ten targeted genes showed that 20 items on biological processes, 17 items on cellular components, and 19 items on molecular functions were significantly enriched. Based on the GO data, we performed GSEA and found that the glutathione metabolic process was significantly enriched in the hemin phenotype. Notably, the expression of glutathione S-transferase omega (GSTO2), which is involved in glutathione metabolism, was decreased after hemin treatment, and overexpression of Gsto2 decreased lipid reactive oxygen species level in hemin-exposed HT22 cells. In addition, the expression of GSTO2 was also decreased in a mouse model of hippocampus-intracerebral hemorrhage (h-ICH). The decreased expression of GSTO2 in the glutathione metabolic process may be involved in ferroptotic neuronal injury following hemorrhagic stroke.

Mitochondrial stress: a key role of neuroinflammation in stroke

Stroke is a clinical syndrome characterized by an acute, focal neurological deficit, primarily caused by the occlusion or rupture of cerebral blood vessels. In stroke, neuroinflammation emerges as a pivotal event contributing to neuronal cell death. The occurrence and progression of neuroinflammation entail intricate processes, prominently featuring mitochondrial dysfunction and adaptive responses. Mitochondria, a double membrane-bound organelle are recognized as the "energy workshop" of the body. Brain is particularly vulnerable to mitochondrial disturbances due to its high energy demands from mitochondria-related energy production. The interplay between mitochondria and neuroinflammation plays a significant role in the pathogenesis of stroke. The biological and pathological consequences resulting from mitochondrial stress have substantial implications for cerebral function. Mitochondrial stress serves as an adaptive mechanism aimed at mitigating the stress induced by the import of misfolded proteins, which occurs in response to stroke. This adaptive response involves a reduction in misfolded protein accumulation and overall protein synthesis. The influence of mitochondrial stress on the pathological state of stroke is underscored by its capacity to interact with neuroinflammation. The impact of mitochondrial stress on neuroinflammation varies according to its severity. Moderate mitochondrial stress can bolster cellular adaptive defenses, enabling cells to better withstand detrimental stressors. In contrast, sustained and excessive mitochondrial stress detrimentally affects cellular and tissue integrity. The relationship between neuroinflammation and mitochondrial stress depends on the degree of mitochondrial stress present. Understanding its role in stroke pathogenesis is instrumental in excavating the novel treatment of stroke. This review aims to provide the evaluation of the cross-talk between mitochondrial stress and neuroinflammation within the context of stroke. We aim to reveal how mitochondrial stress affects neuroinflammation environment in stroke.

TonEBP: A Key Transcription Factor in Microglia Following Intracerebral Hemorrhage Induced-Neuroinflammation

Transcription factors within microglia contribute to the inflammatory response following intracerebral hemorrhage (ICH). Therefore, we employed bioinformatics screening to identify the potential transcription factor tonicity-responsive enhancer-binding protein (TonEBP) within microglia. Inflammatory stimuli can provoke an elevated expression of TonEBP in microglia. Nevertheless, the expression and function of microglial TonEBP in ICH-induced neuroinflammation remain ambiguous. In our recent research, we discovered that ICH instigated an increased TonEBP in microglia in both human and mouse peri-hematoma brain tissues. Furthermore, our results indicated that TonEBP knockdown mitigates lipopolysaccharide (LPS)-induced inflammation and the activation of NF-κB signaling in microglia. In order to more deeply comprehend the underlying molecular mechanisms of how TonEBP modulates the inflammatory response, we sequenced the transcriptomes of TonEBP-deficient cells and sought potential downstream target genes of TonEBP, such as Pellino-1 (PELI1). PELI has been previously reported to mediate nuclear factor-κB (NF-κB) signaling. Through the utilization of CUT & RUN, a dual-luciferase reporter, and qPCR, we confirmed that TonEBP is the transcription factor of Peli1, binding to the Peli1 promoter. In summary, TonEBP may enhance the LPS-induced inflammation and activation of NF-κB signaling via PELI1.

Oxygen glucose deprivation-pretreated astrocyte-derived exosomes attenuates intracerebral hemorrhage (ICH)-induced BBB disruption through miR-27a-3p /ARHGAP25/Wnt/β-catenin axis

BACKGROUND

Blood brain barrier (BBB) breakdown is one of the key mechanisms of secondary brain injury following intracerebral hemorrhage (ICH). Astrocytes interact with endothelial and regulate BBB integrity via paracrine signaling factors. More and more studies reveal astrocyte-derived extracellular vesicles (ADEVs) as an important way of intercellular communication. However, the role of ADEV in BBB integrity after ICH remains unclear.

METHODS

ADEVs were obtained from astrocytes with or without oxygen and glucose deprivation (OGD) pre-stimulation and the role of ADEVs in ICH was investigated using ICH mice model and ICH cell model. The potential regulatory effect of ADEVs on endothelial barrier integrity was identified by TEER, western blot and immunofluorescence in vitro. In vivo, functional evaluation, Evans-blue leakage and tight junction proteins (TJPs) expression were analyzed. MiRNA sequencing revealed that microRNA-27a-3p (miR-27a-3p) was differentially expressed miRNA in the EVs from OGD-pretreated astrocytes compared with normal control. The regulatory mechanism of miR-27a-3p was assessed using Luciferase assay, RT-PCR, western blot and immunofluorescence.

RESULTS

OGD-activated astrocytes reduced hemin-induced endothelial hyper-permeability through secreting EVs. OGD-activated ADEVs alleviated BBB dysfunction after ICH in vivo and in vitro. MicroRNA microarray analysis indicated that miR-27a-3p is a major component that was highly expressed miRNA in OGD pretreated-ADEVs. OGD-ADEVs mitigated BBB injury through transferring miR-27a-3p into bEnd.3 cells and regulating ARHGAP25/Wnt/β-catenin pathway.

CONCLUSION

Taken together, these findings firstly revealed that miR-27a-3p, as one of the main components of OGD-pretreated ADEVs, attenuated BBB destruction and improved neurological deficits following ICH by regulating endothelial ARHGAP25/Wnt/β-catenin axis. OGD-ADEVs might be a novel strategy for the treatment of ICH. this study implicates that EVs from OGD pre-stimulated astrocytes.

PRMT inhibitor promotes SMN2 exon 7 inclusion and synergizes with nusinersen to rescue SMA mice

Spinal muscular atrophy (SMA) is a leading genetic cause of infant mortality. The advent of approved treatments for this devastating condition has significantly changed SMA patients' life expectancy and quality of life. Nevertheless, these are not without limitations, and research efforts are underway to develop new approaches for improved and long-lasting benefits for patients. Protein arginine methyltransferases (PRMTs) are emerging as druggable epigenetic targets, with several small-molecule PRMT inhibitors already in clinical trials. From a screen of epigenetic molecules, we have identified MS023, a potent and selective type I PRMT inhibitor able to promote SMN2 exon 7 inclusion in preclinical SMA models. Treatment of SMA mice with MS023 results in amelioration of the disease phenotype, with strong synergistic amplification of the positive effect when delivered in combination with the antisense oligonucleotide nusinersen. Moreover, transcriptomic analysis revealed that MS023 treatment has minimal off-target effects, and the added benefit is mainly due to targeting neuroinflammation. Our study warrants further clinical investigation of PRMT inhibition both as a stand-alone and add-on therapy for SMA.

2-Deoxyglucose drives plasticity via an adaptive ER stress-ATF4 pathway and elicits stroke recovery and Alzheimer's resilience

Intermittent fasting (IF) is a diet with salutary effects on cognitive aging, Alzheimer's disease (AD), and stroke. IF restricts a number of nutrient components, including glucose. 2-deoxyglucose (2-DG), a glucose analog, can be used to mimic glucose restriction. 2-DG induced transcription of the pro-plasticity factor, Bdnf, in the brain without ketosis. Accordingly, 2-DG enhanced memory in an AD model (5xFAD) and functional recovery in an ischemic stroke model. 2-DG increased Bdnf transcription via reduced N-linked glycosylation, consequent ER stress, and activity of ATF4 at an enhancer of the Bdnf gene, as well as other regulatory regions of plasticity/regeneration (e.g., Creb5, Cdc42bpa, Ppp3cc, and Atf3) genes. These findings demonstrate an unrecognized role for N-linked glycosylation as an adaptive sensor to reduced glucose availability. They further demonstrate that ER stress induced by 2-DG can, in the absence of ketosis, lead to the transcription of genes involved in plasticity and cognitive resilience as well as proteostasis.

Mechanistic impacts of bacterial diet on dopaminergic neurodegeneration in a Caenorhabditis elegans α-synuclein model of Parkinson's disease

Failure of inherently protective cellular processes and misfolded protein-associated stress contribute to the progressive loss of dopamine (DA) neurons characteristic of Parkinson's disease (PD). A disease-modifying role for the microbiome has recently emerged in PD, representing an impetus to employ the soil-dwelling nematode, Caenorhabditis elegans, as a preclinical model to correlate changes in gene expression with neurodegeneration in transgenic animals grown on distinct bacterial food sources. Even under tightly controlled conditions, hundreds of differentially expressed genes and a robust neuroprotective response were discerned between clonal C. elegans strains overexpressing human alpha-synuclein in the DA neurons fed either one of only two subspecies of Escherichia coli. Moreover, this neuroprotection persisted in a transgenerational manner. Genetic analysis revealed a requirement for the double-stranded RNA (dsRNA)-mediated gene silencing machinery in conferring neuroprotection. In delineating the contribution of individual genes, evidence emerged for endopeptidase activity and heme-associated pathway(s) as mechanistic components for modulating dopaminergic neuroprotection.

Ferroptosis: From regulation of lipid peroxidation to the treatment of diseases

Ferroptosis is a regulated cell death mainly manifested by iron-dependent lipid peroxide accumulation. The leading cause of ferroptosis is the imbalance of intracellular oxidative systems (e.g., LOXs, POR, ROS) and antioxidant systems (e.g., GSH/GPx4, CoQ10/FSP1, BH4/GCH1), which is regulated by a complex network. In the past decade, this metabolic network has been continuously refined, and the links with various pathophysiological processes have been gradually established. Apoptosis has been regarded as the only form of regulated cell death for a long time, and the application of chemotherapeutic drugs to induce apoptosis of cancer cells is the mainstream method. However, studies have reported that cancer cells' key features are resistance to apoptosis and chemotherapeutics. For high proliferation, cancer cells often have very active lipid metabolism and iron metabolism, which pave the way for ferroptosis. Interestingly, researchers found that drug-resistant or highly aggressive cancer cells are more prone to ferroptosis. Therefore, ferroptosis may be a potential strategy to eliminate cancer cells. In addition, links between ferroptosis and other diseases, such as neurological disorders and ischemia-reperfusion injury, have also been found. Understanding these diseases from the perspective of ferroptosis may provide new insights into clinical treatment. Herein, the metabolic processes in ferroptosis are reviewed, and the potential mechanisms and targets of ferroptosis in different diseases are summarized.

HIF prolyl hydroxylase 2/3 deletion disrupts astrocytic integrity and exacerbates neuroinflammation

Astrocytes constitute the parenchymal border of the blood-brain barrier (BBB), modulate the exchange of soluble and cellular elements, and are essential for neuronal metabolic support. Thus, astrocytes critically influence neuronal network integrity. In hypoxia, astrocytes upregulate a transcriptional program that has been shown to boost neuroprotection in several models of neurological diseases. We investigated transgenic mice with astrocyte-specific activation of the hypoxia-response program by deleting the oxygen sensors, HIF prolyl-hydroxylase domains 2 and 3 (Phd2/3). We induced astrocytic Phd2/3 deletion after onset of clinical signs in experimental autoimmune encephalomyelitis (EAE) that led to an exacerbation of the disease mediated by massive immune cell infiltration. We found that Phd2/3-ko astrocytes, though expressing a neuroprotective signature, exhibited a gradual loss of gap-junctional Connexin-43 (Cx43), which was induced by vascular endothelial growth factor-alpha (Vegf-a) expression. These results provide mechanistic insights into astrocyte biology, their critical role in hypoxic states, and in chronic inflammatory CNS diseases.

Ferroptosis and Neurodegenerative Diseases: Insights into the Regulatory Roles of SLC7A11

Programed cell death plays a key role in promoting human development and maintaining homeostasis. Ferroptosis is a recently identified pattern of programmed cell death that is closely associated with the onset and progression of neurodegenerative diseases. Ferroptosis is mainly caused by the intracellular accumulation of iron-dependent lipid peroxides. The cysteine/glutamate antibody Solute carrier family 7 member 11 (SLC7A11, also known as xCT) functions to import cysteine for glutathione biosynthesis and antioxidant defense. SLC7A11 has a significant impact on ferroptosis, and inhibition of SLC7A11 expression promotes ferroptosis. Moreover, SLC7A11 is also closely associated with neurodegenerative diseases. In this paper, we summarize the relationship between ferroptosis and neurodegenerative diseases and the role of SLC7A11 during this process. The various regulatory mechanisms of SLC7A11 are also discussed. In conclusion, we are looking forward to a theoretical basis for further understanding the occurrence and development of ferroptosis in SLC7A11 and neurodegenerative diseases, and to seek new clues for the treatment of neurodegenerative diseases.

Temporary induction of hypoxic adaptations by preconditioning fails to enhance Schwann cell transplant survival after spinal cord injury

Hypoxic preconditioning is protective in multiple models of injury and disease, but whether it is beneficial for cells transplanted into sites of spinal cord injury (SCI) is largely unexplored. In this study, we analyzed whether hypoxia-related preconditioning protected Schwann cells (SCs) transplanted into the contused thoracic rat spinal cord. Hypoxic preconditioning was induced in SCs prior to transplantation by exposure to either low oxygen (1% O₂ ) or pharmacological agents (deferoxamine or adaptaquin). All preconditioning approaches induced hypoxic adaptations, including increased expression of HIF-1α and its target genes. These adaptations, however, were transient and resolved within 24 h of transplantation. Pharmacological preconditioning attenuated spinal cord oxidative stress and enhanced transplant vascularization, but it did not improve either transplanted cell survival or recovery of sensory or motor function. Together, these experiments show that hypoxia-related preconditioning is ineffective at augmenting either cell survival or the functional outcomes of SC-SCI transplants. They also reveal that the benefits of hypoxia-related adaptations induced by preconditioning for cell transplant therapies are not universal.

P53 protein and the diseases in central nervous system

P53 protein is the product of P53 gene, which is a well acknowledged tumor suppressor gene. The function of P53 and the relevant mechanisms of anti-neoplasm have raised the interest of researchers since many years ago. It is demonstrated that P53 is a basic cell cycle regulator and a strong inhibitor for versatile cancers in humans. However, most research focuses on other organs and systems instead of the central nervous system (CNS). In fact, in recent years, more and more studies have been suggesting that P53 plays a significant role in multiple CNS tumors and other diseases and disorders such as cerebral stroke and neurodegenerative diseases. In this work, we mainly reviewed the P53's relationship with CNS tumors, cerebral stroke and neurodegenerative diseases, together with the relevant mechanisms, aiming to summarize the research achievements and providing new insight to the future study on diseases in CNS.

The neuroprotective effects of targeting key factors of neuronal cell death in neurodegenerative diseases: The role of ER stress, oxidative stress, and neuroinflammation

Neuronal loss is one of the striking causes of various central nervous system (CNS) disorders, including major neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and Amyotrophic lateral sclerosis (ALS). Although these diseases have different features and clinical manifestations, they share some common mechanisms of disease pathology. Progressive regional loss of neurons in patients is responsible for motor, memory, and cognitive dysfunctions, leading to disabilities and death. Neuronal cell death in neurodegenerative diseases is linked to various pathways and conditions. Protein misfolding and aggregation, mitochondrial dysfunction, generation of reactive oxygen species (ROS), and activation of the innate immune response are the most critical hallmarks of most common neurodegenerative diseases. Thus, endoplasmic reticulum (ER) stress, oxidative stress, and neuroinflammation are the major pathological factors of neuronal cell death. Even though the exact mechanisms are not fully discovered, the notable role of mentioned factors in neuronal loss is well known. On this basis, researchers have been prompted to investigate the neuroprotective effects of targeting underlying pathways to determine a promising therapeutic approach to disease treatment. This review provides an overview of the role of ER stress, oxidative stress, and neuroinflammation in neuronal cell death, mainly discussing the neuroprotective effects of targeting pathways or molecules involved in these pathological factors.

Role of Necroptosis in Central Nervous System Diseases

Necroptosis is a type of precisely regulated necrotic cell death activated in caspase-deficient conditions. Multiple factors initiate the necroptotic signaling pathway, including toll-like receptor 3/4, tumor necrosis factor (TNF), dsRNA viruses, and T cell receptors. Presently, TNF-induced necroptosis via the phosphorylation of three key proteins, receptor-interacting protein kinase 1, receptor-interacting protein kinase 3, and mixed lineage kinase domain-like protein, is the best-characterized process. Necroptosis induced by Z-DNA-binding protein 1 (ZBP-1) and toll/interleukin-1 receptor (TIR)-domain-containing adapter-inducing interferon (TRIF) plays a significant role in infectious diseases, such as influenza A virus, Zika virus, and herpesvirus infection. An increasing number of studies have demonstrated the close association of necroptosis with multiple diseases, and disrupting necroptosis has been confirmed to be effective for treating (or managing) these diseases. The central nervous system (CNS) exhibits unique physiological structures and immune characteristics. Necroptosis may occur without the sequential activation of signal proteins, and the necroptosis of supporting cells has more important implications in disease development. Additionally, necroptotic signals can be activated in the absence of necroptosis. Here, we summarize the role of necroptosis and its signal proteins in CNS diseases and characterize typical necroptosis regulators to provide a basis for the further development of therapeutic strategies for treating such diseases. In the present review, relevant information has been consolidated from recent studies (from 2010 until the present), excluding the patents in this field.

Thiamine insufficiency induces Hypoxia Inducible Factor-1α as an upstream mediator for neurotoxicity and AD-like pathology

Insufficiencies of the micronutrient thiamine (Vitamin B1) have been associated with inducing Alzheimer's disease (AD)-like neuropathology. The hypometabolic state associated with chronic thiamine insufficiency (TI) has been demonstrated to be a contributor towards the development of amyloid plaque deposition and neurotoxicity. However, the molecular mechanism underlying TI induced AD pathology is still unresolved. Previously, we have established that TI stabilizes the metabolic stress transcriptional factor, Hypoxia Inducible Factor-1α (HIF1α). Utilizing neuronal hippocampal cells (HT22), TI-induced HIF1α activation triggered the amyloidogenic cascade through transcriptional expression and increased activity of β-secretase (BACE1). Knockdown and pharmacological inhibition of HIF1α during TI significantly reduced BACE1 and C-terminal Fragment of 99 amino acids (C99) formation. TI also increased the expression of the HIF1α regulated pro-apoptotic protein, BCL2/adenovirus E1B 19 kDa protein-interacting protein (BNIP3). Correspondingly, cell toxicity during TI conditions was significantly reduced with HIF1α and BNIP3 knockdown. The role of BNIP3 in TI-mediated toxicity was further highlighted by localization of dimeric BNIP3 into the mitochondria and nuclear accumulation of Endonuclease G. Subsequently, TI decreased mitochondrial membrane potential and enhanced chromatin fragmentation. However, cell toxicity via the HIF1α/BNIP3 cascade required TI induced oxidative stress. HIF1α, BACE1 and BNIP3 expression was induced in 3xTg-AD mice after TI and administration with the HIF1α inhibitor YC1 significantly attenuated HIF1α and target genes levels in vivo. Overall, these findings demonstrate a critical stress response during TI involving the induction of HIF1α transcriptional activity that directly promotes neurotoxicity and AD-like pathology.

The Proteostasis Network: A Global Therapeutic Target for Neuroprotection after Spinal Cord Injury

Proteostasis (protein homeostasis) is critical for cellular as well as organismal survival. It is strictly regulated by multiple conserved pathways including the ubiquitin-proteasome system, autophagy, the heat shock response, the integrated stress response, and the unfolded protein response. These overlapping proteostasis maintenance modules respond to various forms of cellular stress as well as organismal injury. While proteostasis restoration and ultimately organism survival is the main evolutionary driver of such a regulation, unresolved disruption of proteostasis may engage pro-apoptotic mediators of those pathways to eliminate defective cells. In this review, we discuss proteostasis contributions to the pathogenesis of traumatic spinal cord injury (SCI). Most published reports focused on the role of proteostasis networks in acute/sub-acute tissue damage post-SCI. Those reports reveal a complex picture with cell type- and/or proteostasis mediator-specific effects on loss of neurons and/or glia that often translate into the corresponding modulation of functional recovery. Effects of proteostasis networks on such phenomena as neuro-repair, post-injury plasticity, as well as systemic manifestations of SCI including dysregulation of the immune system, metabolism or cardiovascular function are currently understudied. However, as potential interventions that target the proteostasis networks are expected to impact many cell types across multiple organ systems that are compromised after SCI, such therapies could produce beneficial effects across the wide spectrum of highly variable human SCI.

Selenium Alleviates Cerebral Ischemia/Reperfusion Injury by Regulating Oxidative Stress, Mitochondrial Fusion and Ferroptosis

To clarify the potential role of selenium (Se) on cerebral ischemia/reperfusion (I/R) injury, we utilized mouse middle cerebral artery occlusion (MCAO) followed by reperfusion as an animal model and oxygen-glucose deprivation and reoxygenation (OGD/R) to treat N2a cells as a cell model, respectively. MCAO model was established in mice and then divided into different groups with or without Se treatment. TTC staining was used to observe whether the cerebral I/R modeling was successful, and the apoptosis level was determined by TUNEL staining. The expression of GPx-4 and p22phox was assessed by western blot. In vitro experiments, the OGD/R induced oxidative stress in N2a cells was assessed by levels of GSH/GSSG, malondialdehyde, superoxide dismutase and iron content, respectively. QRT-PCR was used to detect the mRNA levels of Cox-2, Fth1, Mfn1 and mtDNA in N2a cells. JC-1 staining and flow cytometry was performed to detect the mitochondrial membrane potential. Se treatment alleviated cerebral I/R injury and improved the survival rate of mice. Additionally, Se treatment apparently attenuated oxidative stress and inhibited iron accumulation in MCAO model mice and OGD/R model of N2a cells. In terms of its mechanism, Se could up-regulate Mfn1 expression to alleviate oxidative stress and ferroptosis by promoting mitochondrial fusion in vivo and vitro. These findings suggest that Se may have great potential in alleviating cerebral I/R injury.

Ferroptosis is involved in regulating perioperative neurocognitive disorders: emerging perspectives

Since the twenty-first century, the development of technological advances in anesthesia and surgery has brought benefits to human health. However, the adverse neurological effects of perioperative-related factors (e.g., surgical trauma, anesthesia, etc.) as stressors cannot be ignored as well. The nervous system appears to be more "fragile" and vulnerable to damage in developing and aging individuals. Ferroptosis is a novel form of programmed cell death proposed in 2012. In recent years, the regulation of ferroptosis to treat cancer, immune system disorders, and neurodegenerative diseases have seen an unprecedented surge of interest. The association of ferroptosis with perioperative neurocognitive disorders has also received much attention. Cognitive impairment can not only affect the individual's quality of life, but also impose a burden on the family and society. Therefore, the search for effective preventive and therapeutic methods to alleviate cognitive impairment caused by perioperative-related factors is a challenge that needs to be urgently addressed. In our review, we first briefly describe the connection between iron accumulation in neurons and impairment of brain function during development and aging. It is followed by a review of the pathways of ferroptosis, mainly including iron metabolism, amino acid metabolism, and lipid metabolism pathway. Furthermore, we analyze the connection between ferroptosis and perioperative-related factors. The surgery itself, general anesthetic drugs, and many other relevant factors in the perioperative period may affect neuronal iron homeostasis. Finally, we summarize the experimental evidence for ameliorating developmental and degenerative neurotoxicity by modulating ferroptosis. The suppression of ferroptosis seems to provide the possibility to prevent and improve perioperative neurocognitive impairment.

Core transcription programs controlling injury-induced neurodegeneration of retinal ganglion cells

Regulatory programs governing neuronal death and axon regeneration in neurodegenerative diseases remain poorly understood. In adult mice, optic nerve crush (ONC) injury by severing retinal ganglion cell (RGC) axons results in massive RGC death and regenerative failure. We performed an in vivo CRISPR-Cas9-based genome-wide screen of 1,893 transcription factors (TFs) to seek repressors of RGC survival and axon regeneration following ONC. In parallel, we profiled the epigenetic and transcriptional landscapes of injured RGCs by ATAC-seq and RNA-seq to identify injury-responsive TFs and their targets. These analyses converged on four TFs as critical survival regulators, of which ATF3/CHOP preferentially regulate pathways activated by cytokines and innate immunity and ATF4/C/EBPγ regulate pathways engaged by intrinsic neuronal stressors. Manipulation of these TFs protects RGCs in a glaucoma model. Our results reveal core transcription programs that transform an initial axonal insult into a degenerative process and suggest novel strategies for treating neurodegenerative diseases.

Neuroprotective Effects of Quercetin on Ischemic Stroke: A Literature Review

Ischemic stroke (IS) is characterized by high recurrence and disability; however, its therapies are very limited. As one of the effective methods of treating acute attacks of IS, intravenous thrombolysis has a clear time window. Quercetin, a flavonoid widely found in vegetables and fruits, inhibits immune cells from secreting inflammatory cytokines, thereby reducing platelet aggregation and limiting inflammatory thrombosis. In pre-clinical studies, it has been shown to exhibit neuroprotective effects in patients with ischemic brain injury. However, its specific mechanism of action remains unknown. Therefore, this review aims to use published data to elucidate the potential value of quercetin in patients with ischemic brain injury. This article also reviews the plant sources, pharmacological effects, and metabolic processes of quercetin in vivo, thus focusing on its mechanism in inhibiting immune cell activation and inflammatory thrombosis as well as promoting neuroprotection against ischemic brain injury.

Reduction of lactoferrin aggravates neuronal ferroptosis after intracerebral hemorrhagic stroke in hyperglycemic mice

Diabetic hyperglycemia aggravates the prognosis of intracerebral hemorrhagic stroke (ICH) in the clinic. In addition to hematoma expansion and increased inflammation, how diabetic hyperglycemia affects the outcomes of ICH is still unclear. We found that streptozotocin-induced diabetic hyperglycemia not only increased neutrophil infiltration, but also changed the gene expression profile of neutrophils, including lactoferrin (Ltf) encoding gene Ltf. Peroxisome proliferator-activated receptor γ (PPARγ) transcribed Ltf and the lack of neutrophilic Ltf transcription and secretion exacerbated neuronal ferroptosis by accumulating intraneuronal iron. Furthermore, the administration of recombinant Ltf protected against neuronal ferroptosis and improved neurobehavior in hyperglycemic ICH mice, and vice versa. These results indicate that supplementing Ltf or inhibiting neuronal ferroptosis are promising potential strategies to improve the acute outcomes of diabetic ICH in the clinic.

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Neutrophil infiltration and ICH prognosis are aggravated in hyperglycemic mice.

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Hyperglycemia impairs PPAR-γ activity and decreases Ltf expression in neutrophils.

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The lack of neutrophilic Ltf fails to decrease intraneuronal iron and ferroptosis.

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rLtf eases neuronal ferroptosis and neurologic deficits in hyperglycemic ICH mice.

A timeline of oligodendrocyte death and proliferation following experimental subarachnoid hemorrhage

AIMS

White matter (WM) injury is a critical factor associated with worse outcomes following subarachnoid hemorrhage (SAH). However, the detailed pathological changes are not completely understood. This study investigates temporal changes in the corpus callosum (CC), including WM edema and oligodendrocyte death after SAH, and the role of lipocalin-2 (LCN2) in those changes.

METHODS

Subarachnoid hemorrhage was induced in adult wild-type or LCN2 knockout mice via endovascular perforation. Magnetic resonance imaging was performed 4 hours, 1 day, and 8 days after SAH, and T2 hyperintensity changes within the CC were quantified to represent WM edema. Immunofluorescence staining was performed to evaluate oligodendrocyte death and proliferation.

RESULTS

Subarachnoid hemorrhage induced significant CC T2 hyperintensity at 4 hours and 1 day that diminished significantly by 8 days post-procedure. Comparing changes between the 4 hours and 1 day, each individual mouse had an increase in CC T2 hyperintensity volume. Oligodendrocyte death was observed at 4 hours, 1 day, and 8 days after SAH induction, and there was progressive loss of mature oligodendrocytes, while immature oligodendrocytes/oligodendrocyte precursor cells (OPCs) proliferated back to baseline by Day 8 after SAH. Moreover, LCN2 knockout attenuated WM edema and oligodendrocyte death at 24 hours after SAH.

CONCLUSIONS

Subarachnoid hemorrhage leads to T2 hyperintensity change within the CC, which indicates WM edema. Oligodendrocyte death was observed in the CC within 1 day of SAH, with a partial recovery by Day 8. SAH-induced WM injury was alleviated in an LCN2 knockout mouse model.

Structure-Activity Relationships and Transcriptomic Analysis of Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitors

To evaluate the differences in action of commercially available 2-oxoglutarate mimetics and “branched-tail” oxyquinoline inhibitors of hypoxia-inducible factor prolyl hydroxylase (HIF PHD), the inhibitors’ IC₅₀ values in the activation of HIF1 ODD-luciferase reporter were selected for comparative transcriptomics. Structure–activity relationship and computer modeling for the oxyquinoline series of inhibitors led to the identification of novel inhibitors, which were an order of magnitude more active in the reporter assay than roxadustat and vadadustat. Unexpectedly, 2-methyl-substitution in the oxyquinoline core of the best HIF PHD inhibitor was found to be active in the reporter assay and almost equally effective in the pretreatment paradigm of the oxygen-glucose deprivation in vitro model. Comparative transcriptomic analysis of the signaling pathways induced by HIF PHD inhibitors showed high potency of the two novel oxyquinoline inhibitors (#4896-3249 and #5704-0720) at 2 μM concentrations matching the effect of 30 μM roxadustat and 500 μM dimethyl oxalyl glycine in inducing HIF1 and HIF2-linked pathways. The two oxyquinoline inhibitors exerted the same activation of HIF-triggered glycolytic pathways but opposite effects on signaling pathways linked to alternative substrates of HIF PHD 1 and 3, such as p53, NF-κB, and ATF4. This finding can be interpreted as the specificity of the 2-methyl-substitute variant for HIF PHD2.

Bioinformatic Analysis of Co-Expressed Differentially Expressed Genes and Potential Targets for Intracerebral and Subarachnoid Hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) are serious subtypes of hemorrhagic stroke that affect adults and have a high risk of morbidity and mortality; both share certain identical risk factors and clinical features. Recent studies have shown that secondary brain injury (SBI) following ICH and SAH is more life-threatening and lacks effective therapeutic strategies. The aim of this study is to understand the molecular pathogenesis of ICH- or SAH-induced SBI and provide insights to the potential therapeutic options.

METHODS

The original gene expression profile data of tissue microarray studies (GSE24265, GSE13353) was downloaded from the Gene Expression Omnibus (GEO) database. We identified the differentially expressed genes (DEGs) for each disease and co-DEGs between ICH and SAH. The functional enrichment analyses were then analyzed and a protein-protein interaction (PPI) network was constructed to strictly select hub genes via the maximal clique centrality (MCC) method. Additionally, immune infiltration analyses were used to identify the common differently distributed cells in both diseases. Finally, potential target microRNAs (miRNAs) and related targeted drugs were predicted for further studies. The animal model microarrays were used for external validation.

RESULTS

A total of 614 ICH-DEGs, 1272 SAH-DEGs, and 158 co-DEGs were identified in our study. The co-DEGs were significantly enriched in cytotoxicity and inflammation pathways. The top 10 hub genes (CCL20, CXCL1, CXCL3, CXCL8, CXCL16, CXCR2, CXCR4, CCR7, PF4, and PPBP) were then filtered through the PPI networks. Moreover, nTreg, Th17, and dendritic cells and monocytes and macrophages were identified as the common differentially distributed immune cells between ICH and SAH. Additionally, the target miRNAs (e.g., miR-21-5p, miR-590-5p, miR-6834-3p) and related drugs (e.g., ABX-IL8, HUMAX-IL8, Rivanicline) of hub genes were predicted.

CONCLUSIONS

This study identified a variety of key genes and their respective molecular functions involved in both ICH and SAH for better understanding of the cytotoxic and inflammatory pathogenesis of SBI. The predicted targeted miRNAs and related drugs of hub genes not only provide insights into the novel therapeutic strategies but also aid in future studies and drug discovery.

Renoprotective Role of Hypoxia-Inducible Factors and the Mechanism

BACKGROUND

The kidney requires abundant blood supply, and oxygen is transmitted by diffusion through blood vessels. Most physiological metabolism of the kidney depends on oxygen, so it is very sensitive to oxygen. An increasing pool of evidence suggests that hypoxia is involved in almost all acute and chronic kidney diseases (CKDs). Vascular damage, tubular injury, and fibrosis are the main pathologies associated during hypoxia. Hypoxia-inducible factors (HIFs) are the main mediators during hypoxia, but their functions remain controversial. This article reviewed recent studies and described its mechanisms on renoprotection.

SUMMARY

HIF is degraded rapidly during under normal oxygen. But under hypoxia, HIFs accumulate and many target genes are regulated by HIFs. Homeostasis during injury is maintained through these genes. Pretreatment of HIF can protect the kidney from acute hypoxia and can improve repair, but HIF's role in CKD and in renal tumor is still controversial. Due to its mechanism in kidney disease, many drugs toward HIFs are widely researched, even some of which have been used in clinical or in clinical research.

KEY MESSAGES

In this review, we described the known physiological mechanisms, target genes, and renal protective roles of HIFs, and we discussed several drugs that are researched due to such renal protective roles.

Scavenging Free Iron Reduces Arteriolar Microvasospasms After Experimental Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Subarachnoid hemorrhage (SAH) is associated with acute and delayed cerebral ischemia resulting in high acute mortality and severe chronic neurological deficits. Spasms of the pial and intraparenchymal microcirculation (microvasospasms) contribute to acute cerebral ischemia after SAH; however, the underlying mechanisms remain unknown. We hypothesize that free iron (Fe3+) released from hemolytic red blood cells into the subarachnoid space may be involved in microvasospasms formation.

METHODS

Male C57BL/6 mice (n=8/group) received 200 mg/kg of the iron scavenger deferoxamine or vehicle intravenously and were then subjected to SAH by filament perforation. Microvasospasms of pial and intraparenchymal vessels were imaged three hours after SAH by in vivo 2-photon microscopy.

RESULTS

Microvasospasms occurred in all investigated vessel categories down to the capillary level. Deferoxamine significantly reduced the number of microvasospasms after experimental SAH. The effect was almost exclusively observed in larger pial arterioles (>30 µm) covered with blood.

CONCLUSIONS

These results provide proof-of-principle evidence that Fe3+ is involved in the formation of arteriolar microvasospasms after SAH and that arteriolar and capillary microvasospasms are triggered by different mechanisms. Deciphering the mechanisms of Fe3+-induced microvasospasms may result in novel therapeutic strategies for SAH patients.

The neuroprotection of cerebrolysin after spontaneous intracerebral hemorrhage through regulates necroptosis via Akt/ GSK3β signaling pathway

PURPOSE

Spontaneous intracerebral hemorrhage (ICH) is a major cause of death and disability with a huge economic burden worldwide. Cerebrolysin (CBL) has been previously used as a nootropic drug. Necroptosis is a programmed cell death mechanism that plays a vital role in neuronal cell death after ICH. However, the precise role of necroptosis in CBL neuroprotection following ICH has not been confirmed.

METHODS

In the present study, we aimed to investigate the neuroprotective effects and potential molecular mechanisms of CBL in ICH-induced early brain injury (EBI) by regulating neural necroptosis in the C57BL/6 mice model. Mortality, neurological score, brain water content, and neuronal death were evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, Evans blue extravasation, Western blotting, and quantitative real-time polymerase chain reaction (PCR).

RESULTS

The results show that CBL treatment markedly increased the survival rate, neurological score, and neuron survival, and downregulated the protein expression of RIP1 and RIP3, which indicated that CBL-mediated inhibition of necroptosis, and ameliorated neuronal death after ICH. The neuroprotective capacity of CBL is partly dependent on the Akt/GSK3β signaling pathway.

CONCLUSIONS

CBL improves neurological outcomes in mice and reduces neuronal death by protecting against neural necroptosis.

HIF1α stabilization in hypoxia is not oxidant-initiated

Hypoxic adaptation mediated by HIF transcription factors requires mitochondria, which have been implicated in regulating HIF1α stability in hypoxia by distinct models that involve consuming oxygen or alternatively converting oxygen into the second messenger peroxide. Here, we use a ratiometric, peroxide reporter, HyPer to evaluate the role of peroxide in regulating HIF1α stability. We show that antioxidant enzymes are neither homeostatically induced nor are peroxide levels increased in hypoxia. Additionally, forced expression of diverse antioxidant enzymes, all of which diminish peroxide, had disparate effects on HIF1α protein stability. Moreover, decrease in lipid peroxides by glutathione peroxidase-4 or superoxide by mitochondrial SOD, failed to influence HIF1α protein stability. These data show that mitochondrial, cytosolic or lipid ROS were not necessary for HIF1α stability, and favor a model where mitochondria contribute to hypoxic adaptation as oxygen consumers.

Intermittent hypoxia mimicking obstructive sleep apnea aggravates early brain injury following ICH via neuroinflammation and apoptosis

Spontaneous intracerebral hemorrhage (ICH) is a subtype of stroke associated with high mortality and morbidity due to the lack of effective therapy. Obstructive sleep apnea (OSA) has been reported to aggravate early brain injury (EBI) and worsen the overall outcome of patients with ICH. However, the precise role of OSA-mediated neuroinflammation and apoptosis following ICH has not been confirmed. The present study aimed to investigate the neuronal damage induced by OSA and the potential molecular mechanisms by which ICH-induced EBI regulates neural apoptosis in a C57BL/6 mouse ICH model. Mortality, neurological score, brain water content and neuronal death were evaluated by Evans blue extravasation, TUNEL staining, ELISA, analysis of reactive oxygen species/lipid peroxidation and western blotting. The results showed that OSA induction decreased survival rate, neurological score and neuron survival and upregulated the protein expression levels of Caspase-3, Bax, cytokines IL-1β, IL-6 and TNF-α and NF-κB, which indicated that OSA-mediated induction of apoptosis and neuroinflammation aggravated neuronal death following ICH. The molecular mechanism was partly dependent on the activating transcription factor/CHOP pathway. Taken together, the results demonstrated that OSA worsens neurological outcomes in mice and increases neuronal death by enhancing neural apoptosis and neuroinflammation.

Targeting Ferroptosis to Treat Cardiovascular Diseases: A New Continent to Be Explored

Cardiovascular diseases, including cardiomyopathy, myocardial infarction, myocardial ischemia/reperfusion injury, heart failure, vascular injury, stroke, and arrhythmia, are correlated with cardiac and vascular cell death. Ferroptosis is a novel form of non-apoptotic regulated cell death which is characterized by an iron-driven accumulation of lethal lipid hydroperoxides. The initiation and execution of ferroptosis are under the control of several mechanisms, including iron metabolism, glutamine metabolism, and lipid peroxidation. Recently, emerging evidence has demonstrated that ferroptosis can play an essential role in the development of various cardiovascular diseases. Recent researches have shown the ferroptosis inhibitors, iron chelators, genetic manipulations, and antioxidants can alleviate myocardial injury by blocking ferroptosis pathway. In this review, we systematically described the mechanisms of ferroptosis and discussed the role of ferroptosis as a novel therapeutic strategy in the treatment of cardiovascular diseases.

CircLphn3 protects the blood-brain barrier in traumatic brain injury

Circular RNAs (circRNAs) are a new and large group of non-coding RNA molecules that are abundantly expressed in the central nervous system. However, very little is known about their roles in traumatic brain injury. In this study, we firstly screened differentially expressed circRNAs in normal and injured brain tissues of mice after traumatic brain injury. We found that the expression of circLphn3 was substantially decreased in mouse models of traumatic brain injury and in hemin-treated bEnd.3 (mouse brain cell line) cells. After overexpressing circLphn3 in bEnd.3 cells, the expression of the tight junction proteins, ZO-1, ZO-2, and occludin, was upregulated, and the expression of miR-185-5p was decreased. In bEnd.3 cells transfected with miR-185-5p mimics, the expression of ZO-1 was decreased. Dual-luciferase reporter assays showed that circLphn3 bound to miR-185-5p, and that miR-185-5p bound to ZO-1. Additionally, circLphn3 overexpression attenuated the hemin-induced high permeability of the in vitro bEnd.3 cell model of the blood-brain barrier, while miR-185-5p transfection increased the permeability. These findings suggest that circLphn3, as a molecular sponge of miR-185-5p, regulates tight junction proteins' expression after traumatic brain injury, and it thereby improves the permeability of the blood-brain barrier. This study was approved by the Animal Care and Use Committee of Chongqing Medical University of China (approval No. 2021-177) on March 22, 2021.

Emerging Role of Ferroptosis in the Pathogenesis of Ischemic Stroke: A New Therapeutic Target?

Ischemic stroke is one of the main causes of high morbidity, mortality, and disability worldwide; however, the treatment methods are limited and do not always achieve satisfactory results. The pathogenesis of ischemic stroke is complex, defined by multiple mechanisms; among them, programmed death of neuronal cells plays a significant role. Ferroptosis is a novel type of regulated cell death characterized by iron redistribution or accumulation and increased lipid peroxidation in the membrane. Ferroptosis is implicated in many pathological conditions, such as cancer, neurodegenerative diseases, and ischemia-reperfusion injury. In this review, we summarize current research findings on ferroptosis, including possible molecular mechanisms and therapeutic applications of ferroptosis regulators, with a focus on the involvement of ferroptosis in the pathogenesis and treatment of ischemic stroke. Understanding the role of ferroptosis in ischemic stroke will throw some light on the development of methods for diagnosis, treatment, and prevention of this devastating disease.

Perampanel, an AMPAR antagonist, alleviates experimental intracerebral hemorrhage‑induced brain injury via necroptosis and neuroinflammation

Spontaneous intracerebral hemorrhage (ICH) is a subtype of stroke with high mortality and morbidity due to the lack of effective therapies. The alpha‑amino‑3‑hydroxy‑5‑methyl‑4‑isoxazolepropionic acid receptor antagonist perampanel has been reported to alleviate early brain injury following subarachnoid hemorrhage and traumatic brain injury by reducing reactive oxygen species, apoptosis, autophagy, and necroptosis. Necroptosis is a caspase‑independent programmed cell death mechanism that serves a vital role in neuronal cell death following ICH. However, the precise role of necroptosis in perampanel‑mediated neuroprotection following ICH has not been confirmed. The present study aimed to investigate the neuroprotective effects and potential molecular mechanisms of perampanel in ICH‑induced early brain injury by regulating neural necroptosis in C57BL/6 mice and in a hemin‑induced neuron damage cell culture model. Mortality, neurological score, brain water content, and neuronal death were evaluated. The results demonstrated that perampanel treatment increased the survival rate and neurological score, and increased neuron survival. In addition, perampanel treatment downregulated the protein expression levels of receptor interacting serine/threonine kinase (RIP) 1, RIP3, and mixed lineage kinase domain like pseudokinase, and of the cytokines IL‑1β, IL‑6, TNF‑α, and NF‑κB. These results indicated that perampanel‑mediated inhibition of necroptosis and neuroinflammation ameliorated neuronal death in vitro and in vivo following ICH. The neuroprotective capacity of perampanel was partly dependent on the PTEN pathway. Taken together, the results of the present study demonstrated that perampanel improved neurological outcomes in mice and reduced neuronal death by protecting against neural necroptosis and neuroinflammation.

Bioinformatics Analysis Identifies Potential Ferroptosis Key Genes in the Pathogenesis of Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a dangerous neurological disease. The mechanism of ferroptosis in ICH remains unclear. Using bioinformatics analysis, we aimed to identify the key molecules involved in ferroptosis and provide treatment targets for ICH to further explore the mechanism of ferroptosis in ICH. GSE24265 was downloaded from the Gene Expression Omnibus (GEO) dataset and intersected with ferroptosis genes. A total of 45 differentially expressed genes (DEGs) were selected, most of which were involved in the TNF signaling pathway and oxidative stress response. Key modules constructed by the protein–protein interaction (PPI) network analysis and screening of genes related to the TNF signaling pathway led to the confirmation of the following genes of interest: MAPK1, MAPK8, TNFAIP3, ATF4, and SLC2A1. Moreover, MAPK1 was one of the key genes related to TNF signaling and oxidative stress, and it may play an important role in ferroptosis after cerebral hemorrhage. The MAPK1-related molecules included hsa-miR-15b-5P, hsa-miR-93-5P, miR-20b-5p, SNHG16, XIST, AC084219.4, RP11-379K17.11, CTC-444N24.11, GS1-358P8.4, CTB-89H12.4, RP4-773N10.5, and FGD5-AS1. We also generated a hemorrhage rat model, which was used to conduct exercise intervention in ICH rats, and qRT-PCR was used to assess the expression levels of our genes of interest. The mRNA levels after cerebral hemorrhage showed that MAPK1, ATF4, SLC2A1, and TNFAIP3 were upregulated, whereas MAPK8 was downregulated. Treadmill training increased the expression of anti-inflammatory molecules TNFAIP3 and SLC2A1 and reduced the expression of MAPK1, ATF4, and MAPK8, indicating that treadmill training may be utilized as antioxidant therapy to decrease neuronal ferroptosis. The results of this study indicated that the MAPK1-related mRNA–miRNA–lncRNA interaction chain could be potentially employed as a biomarker of the inception and progression of ferroptosis after cerebral hemorrhage.

Neuritin improves the neurological functional recovery after experimental intracerebral hemorrhage in mice

Stroke is one of the leading causes of death worldwide, with intracerebral hemorrhage (ICH) being the most lethal subtype. Neuritin (Nrn) is a neurotropic factor that has been reported to have neuroprotective effects in acute brain and spinal cord injury. However, whether Nrn has a protective role in ICH has not been investigated. In this study, ICH was induced in C57BL/6 J mice by injection of collagenase VII, while the overexpression of Nrn in the striatum was induced by an adeno-associated virus serotype 9 (AAV9) vector. We found that compared with GFP-ICH mice, Nrn-ICH mice showed improved performance in the corner, cylinder and forelimb tests after ICH, and showed less weight loss and more rapid weight recovery. Overexpression of Nrn reduced brain lesions, edema, neuronal death and white matter and synaptic integrity dysfunction caused by ICH. Western blot results showed that phosphorylated PERK and ATF4 were significantly inhibited, while phosphorylation of Akt/mammalian target of rapamycin was increased in the Nrn-ICH group, compared with the GFP-ICH group. Whole cell recording from motor neurons indicated that overexpression of Nrn reversed the decrease of spontaneous excitatory postsynaptic currents (sEPSCs) and action potential frequencies induced by ICH. These data show that Nrn improves neurological deficits in mice with ICH by reducing brain lesions and edema, inhibiting neuronal death, and possibly by increasing neuronal connections.

Treatment with hypoxia-mimetics protects cultured rat Schwann cells against oxidative stress-induced cell death

Schwann cell (SC) grafts promote axon regeneration in the injured spinal cord, but transplant efficacy is diminished by a high death rate in the first 2-3 days postimplantation. Both hypoxic preconditioning and pharmacological induction of the cellular hypoxic response can drive cellular adaptations and improve transplant survival in a number of disease/injury models. Hypoxia-inducible factor 1 alpha (HIF-1α), a regulator of the cellular response to hypoxia, is implicated in preconditioning-associated protection. HIF-1α cellular levels are regulated by the HIF-prolyl hydroxylases (HIF-PHDs). Pharmacological inhibition of the HIF-PHDs mimics hypoxic preconditioning and provides a method to induce adaptive hypoxic responses without direct exposure to hypoxia. In this study, we show that hypoxia-mimetics, deferoxamine (DFO) and adaptaquin (AQ), enhance HIF-1α stability and HIF-1α target gene expression. Expression profiling of hypoxia-related genes demonstrates that HIF-dependent and HIF-independent expression changes occur. Analyses of transcription factor binding sites identify several candidate transcriptional co-regulators that vary in SCs along with HIF-1α. Using an in vitro model system, we show that hypoxia-mimetics are potent blockers of oxidative stress-induced death in SCs. In contrast, traditional hypoxic preconditioning was not protective. The robust protection induced by pharmacological preconditioning, particularly with DFO, indicates that pharmacological induction of hypoxic adaptations could be useful for promoting transplanted SC survival. These agents may also be more broadly useful for protecting SCs, as oxidative stress is a major pathway that drives cellular damage in the context of neurological injury and disease, including demyelinating diseases and peripheral neuropathies.

Crosstalk between Oxidative Stress and Ferroptosis/Oxytosis in Ischemic Stroke: Possible Targets and Molecular Mechanisms

Oxidative stress is a key cause of ischemic stroke and an initiator of neuronal dysfunction and death, mainly through the overproduction of peroxides and the depletion of antioxidants. Ferroptosis/oxytosis is a unique, oxidative stress-induced cell death pathway characterized by lipid peroxidation and glutathione depletion. Both oxidative stress and ferroptosis/oxytosis have common molecular pathways. This review summarizes the possible targets and the mechanisms underlying the crosstalk between oxidative stress and ferroptosis/oxytosis in ischemic stroke. This knowledge might help to further understand the pathophysiology of ischemic stroke and open new perspectives for the treatment of ischemic stroke.

A Novel Netrin-1-Derived Peptide Enhances Protection against Neuronal Death and Mitigates of Intracerebral Hemorrhage in Mice

It has been reported that Netrin-1 is involved in neuroprotection following injury to the central nervous system. However, the minimal functional domain of Netrin-1 which can preserve the neuroprotection but avoid the major side effects of Netrin remains elusive. Here, we investigated the neuroprotective effect of a peptide E1 derived from Netrin-1′s EGF3 domain (residues 407–422). We found that it interacts with deleted colorectal carcinoma (DCC) to activate focal adhesion kinase phosphorylation exhibiting neuroprotection. The administration of the peptide E1 was able to improve functional recovery through reduced apoptosis in an experimental murine model of intracerebral hemorrhage (ICH). In summary, we reveal a functional sequence of Netrin-1 that is involved in the recovery process after ICH and identify a candidate peptide for the treatment of ICH.

Activating transcription factor-4 promotes neuronal death induced by Parkinson's disease neurotoxins and α-synuclein aggregates

Parkinson's disease (PD) is a neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra resulting in severe and progressive motor impairments. However, the mechanisms underlying this neuronal loss remain largely unknown. Oxidative stress and ER stress have been implicated in PD and these factors are known to activate the integrated stress response (ISR). Activating transcription factor 4 (ATF4), a key mediator of the ISR, and has been reported to induce the expression of genes involved in cellular homeostasis. However, during prolonged activation ATF4 can also induce the expression of pro-death target genes. Therefore, in the present study, we investigated the role of ATF4 in neuronal cell death in models of PD. We demonstrate that PD neurotoxins (MPP+ and 6-OHDA) and α-synuclein aggregation induced by pre-formed human alpha-synuclein fibrils (PFFs) cause sustained upregulation of ATF4 expression in mouse cortical and mesencephalic dopaminergic neurons. Furthermore, we demonstrate that PD neurotoxins induce the expression of the pro-apoptotic factors Chop, Trb3, and Puma in dopaminergic neurons in an ATF4-dependent manner. Importantly, we have determined that PD neurotoxin and α-synuclein PFF induced neuronal death is attenuated in ATF4-deficient dopaminergic neurons. Furthermore, ectopic expression of ATF4 but not transcriptionally defective ATF4ΔRK restores sensitivity of ATF4-deficient neurons to PD neurotoxins. Finally, we demonstrate that the eIF2α kinase inhibitor C16 suppresses MPP+ and 6-OHDA induced ATF4 activation and protects against PD neurotoxin induced dopaminergic neuronal death. Taken together these results indicate that ATF4 promotes dopaminergic cell death induced by PD neurotoxins and pathogenic α-synuclein aggregates and highlight the ISR factor ATF4 as a potential therapeutic target in PD.

Hypoxia-inducible factor prolyl hydroxylase domain (PHD) inhibition after contusive spinal cord injury does not improve locomotor recovery

Traumatic spinal cord injury (SCI) is a devastating neurological condition that involves both primary and secondary tissue loss. Various cytotoxic events including hypoxia, hemorrhage and blood lysis, bioenergetic failure, oxidative stress, endoplasmic reticulum (ER) stress, and neuroinflammation contribute to secondary injury. The HIF prolyl hydroxylase domain (PHD/EGLN) family of proteins are iron-dependent, oxygen-sensing enzymes that regulate the stability of hypoxia inducible factor-1α (HIF-1α) and also mediate oxidative stress caused by free iron liberated from the lysis of blood. PHD inhibition improves outcome after experimental intracerebral hemorrhage (ICH) by reducing activating transcription factor 4 (ATF4)-driven neuronal death. As the ATF4-CHOP (CCAAT-enhancer-binding protein homologous protein) pathway plays a role in the pathogenesis of contusive SCI, we examined the effects of PHD inhibition in a mouse model of moderate T9 contusive SCI in which white matter damage is the primary driver of locomotor dysfunction. Pharmacological inhibition of PHDs using adaptaquin (AQ) moderately lowers acute induction of Atf4 and Chop mRNAs and prevents the acute decline of oligodendrocyte (OL) lineage mRNAs, but does not improve long-term recovery of hindlimb locomotion or increase chronic white matter sparing. Conditional genetic ablation of all three PHD isoenzymes in OLs did not affect Atf4, Chop or OL mRNAs expression levels, locomotor recovery, and white matter sparing after SCI. Hence, PHDs may not be suitable targets to improve outcomes in traumatic CNS pathologies that involve acute white matter injury.

Unlocking mammalian regeneration through hypoxia inducible factor one alpha signaling

Historically, the field of regenerative medicine has aimed to heal damaged tissue through the use of biomaterials scaffolds or delivery of foreign progenitor cells. Despite 30 years of research, however, translation and commercialization of these techniques has been limited. To enable mammalian regeneration, a more practical approach may instead be to develop therapies that evoke endogenous processes reminiscent of those seen in innate regenerators. Recently, investigations into tadpole tail regrowth, zebrafish limb restoration, and the super-healing Murphy Roths Large (MRL) mouse strain, have identified ancient oxygen-sensing pathways as a possible target to achieve this goal. Specifically, upregulation of the transcription factor, hypoxia-inducible factor one alpha (HIF-1α) has been shown to modulate cell metabolism and plasticity, as well as inflammation and tissue remodeling, possibly priming injuries for regeneration. Since HIF-1α signaling is conserved across species, environmental or pharmacological manipulation of oxygen-dependent pathways may elicit a regenerative response in non-healing mammals. In this review, we will explore the emerging role of HIF-1α in mammalian healing and regeneration, as well as attempts to modulate protein stability through hyperbaric oxygen treatment, intermittent hypoxia therapy, and pharmacological targeting. We believe that these therapies could breathe new life into the field of regenerative medicine.

Some Molecular and Cellular Stress Mechanisms Associated with Neurodegenerative Diseases and Atherosclerosis

Chronic stress is a combination of nonspecific adaptive reactions of the body to the influence of various adverse stress factors which disrupt its homeostasis, and it is also a corresponding state of the organism's nervous system (or the body in general). We hypothesized that chronic stress may be one of the causes occurence of several molecular and cellular types of stress. We analyzed literary sources and considered most of these types of stress in our review article. We examined genes and mutations of nuclear and mitochondrial genomes and also molecular variants which lead to various types of stress. The end result of chronic stress can be metabolic disturbance in humans and animals, leading to accumulation of reactive oxygen species (ROS), oxidative stress, energy deficiency in cells (due to a decrease in ATP synthesis) and mitochondrial dysfunction. These changes can last for the lifetime and lead to severe pathologies, including neurodegenerative diseases and atherosclerosis. The analysis of literature allowed us to conclude that under the influence of chronic stress, metabolism in the human body can be disrupted, mutations of the mitochondrial and nuclear genome and dysfunction of cells and their compartments can occur. As a result of these processes, oxidative, genotoxic, and cellular stress can occur. Therefore, chronic stress can be one of the causes forthe occurrence and development of neurodegenerative diseases and atherosclerosis. In particular, chronic stress can play a large role in the occurrence and development of oxidative, genotoxic, and cellular types of stress.

Oxidative Stress at the Crossroads of Aging, Stroke and Depression

Epidemiologic studies have shown that in the aging society, a person dies from stroke every 3 minutes and 42 seconds, and vast numbers of people experience depression around the globe. The high prevalence and disability rates of stroke and depression introduce enormous challenges to public health. Accumulating evidence reveals that stroke is tightly associated with depression, and both diseases are linked to oxidative stress (OS). This review summarizes the mechanisms of OS and OS-mediated pathological processes, such as inflammation, apoptosis, and the microbial-gut-brain axis in stroke and depression. Pathological changes can lead to neuronal cell death, neurological deficits, and brain injury through DNA damage and the oxidation of lipids and proteins, which exacerbate the development of these two disorders. Additionally, aging accelerates the progression of stroke and depression by overactive OS and reduced antioxidant defenses. This review also discusses the efficacy and safety of several antioxidants and antidepressants in stroke and depression. Herein, we propose a crosstalk between OS, aging, stroke, and depression, and provide potential therapeutic strategies for the treatment of stroke and depression.

In vivo survival strategies for cellular adaptation to hypoxia: HIF1α-dependent suppression of mitochondrial oxygen consumption and decrease of intracellular hypoxia are critical for survival of hypoxic chondrocytes

Hypoxia occurs not only in pathological conditions like cancer and ischemia and in a variety of physiological settings in the adult organism, but also during normal embryonic development. In the inner portion of the fetal growth plate, which is an avascular tissue originating from mesenchymal progenitor cells, chondrocytes experience physiological hypoxia. Hypoxia-Inducible Transcription Factor-1α (HIF1α), a crucial mediator of cellular adaptation to hypoxia, is an essential survival factor for fetal growth plate chondrocytes. This brief review summarizes our current understanding of the survival function of HIF1α during endochondral bone development.

Epigenetic regulators of neuronal ferroptosis identify novel therapeutics for neurological diseases: HDACs, transglutaminases, and HIF prolyl hydroxylases

A major thrust of our laboratory has been to identify how physiological stress is transduced into transcriptional responses that feed back to overcome the inciting stress or its consequences, thereby fostering survival and repair. To this end, we have adopted the use of an in vitro model of ferroptosis, a caspase-independent, but iron-dependent form of cell death (Dixon et al., 2012; Ratan, 2020). In this review, we highlight three distinct epigenetic targets that have evolved from our studies and which have been validated in vivo studies. In the first section, we discuss our studies of broad, pan-selective histone deacetylase (HDAC) inhibitors in ferroptosis and how these studies led to the validation of HDAC inhibitors as candidate therapeutics in a host of disease models. In the second section, we discuss our studies that revealed a role for transglutaminase as an epigenetic modulator of proferroptotic pathways and how these studies set the stage for recent elucidation of monoamines as post-translation modifiers of histone function. In the final section, we discuss our studies of iron-, 2-oxoglutarate-, and oxygen-dependent dioxygenases and the role of one family of these enzymes, the HIF prolyl hydroxylases, in mediating transcriptional events necessary for ferroptosis in vitro and for dysfunction in a host of neurological conditions. Overall, our studies highlight the importance of epigenetic proteins in mediating prodeath and prosurvival responses to ferroptosis. Pharmacological agents that target these epigenetic proteins are showing robust beneficial effects in diverse rodent models of stroke, Parkinson's disease, Huntington's disease, and Alzheimer's disease.

Alpha lipoic acid antagonizes cytotoxicity of cobalt nanoparticles by inhibiting ferroptosis-like cell death

As a main element in the hard metal industry, cobalt is one of the major components of human metal implants. Cobalt-containing implants, especially joint prostheses used for artificial joint replacement, can be corroded due to the complex physiological environment in vivo, producing a large number of nanoscale cobalt particles (Cobalt Nanoparticles, CoNPs). These CoNPs can be first accumulated around the implant to cause adverse local reactions and then enter into the blood vessels followed by reaching the liver, heart, brain, kidney, and other organs through systematic circulation, which leads to multi-system toxicity symptoms. To ensure the long-term existence of cobalt-containing implants in the body, it is urgently required to find out a safe and effective detoxification drug. Herein, we have demonstrated that CoNPs could induce the ferroptosis-like cell death through the enhancement of intracellular reactive oxygen species (ROS) level, cytoplasmic Fe²⁺ level, lipid peroxidation, and consumption of reduced glutathione (GSH) as well as inhibition of glutathione peroxidase 4 (GPX4) activity. Importantly, α-lipoic acid (ALA), a natural antioxidant with the capability to scavenge free radicals and chelate toxic metals, was found to efficiently alleviate the adverse effects of CoNPs. The present study illustrates a new mechanism of CoNPs mediated by ferroptosis-like cytotoxicity and discloses an effective method for the detoxification of CoNPs by employing the natural antioxidant of ALA, providing a basis for further in vivo detoxification study.