Hypoxia-inducible factor-1α in acute ischemic stroke: neuroprotection for better clinical outcome

Association Between Hypoxia-Inducible Factor-1α and Neurological Diseases: A Bidirectional Two-Sample Mendelian Randomization Analysis

BACKGROUND

Previous studies have suggested that hypoxia-inducible factor 1-α (HIF-1α) exerted multiple effects on different central nervous system disorders. However, it is still uncertain whether plasma HIF-1α can be a causal indicator for the relevant diseases. This study aimed to test the causality relationship between plasma HIF-1α and neurological diseases, including cerebrovascular diseases, migraines, and neurodegenerative diseases with a Mendelian randomization (MR) method.

METHODS

Single-nucleotide polymorphisms (SNPs) genetically representing plasma HIF-1α were screened as instrumental variables (IVs). Summary-level data for neurological disorder from genome-wide association studies (GWAS) were identified as outcomes. The causal effects between the IVs and outcomes were determined via the major analysis of inverse-variance-weighted (IVW) method. The reverse causal direction was also performed to investigate the possibility of reverse causation.

RESULTS

The findings revealed that plasma HIF-1α was identified to be genetically associated with cardioembolic stroke (CES) (OR = 0.885; 95% confidence interval [CI] = 0.796-0.985, p = 0.026), migraine (OR = 0.941, 95% CI = 0.888-0.998, p = 0.041), and drug-induced migraine without aura (MOA) (OR = 0.586, 95% CI = 0.375-0.916, p = 0.019). There was no association identified in plasma HIF-1α with subarachnoid hemorrhage (SAH), other stroke and migraine subtype, and neurodegenerative disorders. The reverse-MR analysis revealed that the above-stated neurological diseases did not have a causal effect on plasma HIF-1α levels. Sensitivity and validation analyses support that the above results are stable.

CONCLUSIONS

Our research indicated that plasma HIF-1α may have a causal effect on the risk of CES, migraine and drug-induced MOA, providing new insights for those disease prevention and therapeutic approaches.

Mechanistic exploration of ubiquitination-mediated pathways in cerebral ischemic injury

The ubiquitin-proteasome system (UPS) plays a pivotal role in regulating protein homeostasis and cellular processes, including protein degradation, trafficking, DNA repair, and cell signaling. During cerebral ischemia, ischemic conditions profoundly disrupt UPS activity, leading to proteasomal dysfunction and the accumulation of abnormal proteins. This imbalance contributes to neuronal injury and cell death observed in ischemic stroke. The UPS is intricately linked to various signaling pathways crucial for neuronal survival, inflammation, and cellular stress response, such as NF-κB, TRIM, TRIP, JAK-STAT, PI3K/Akt, and ERK1/2. Alterations in the ubiquitination process can significantly impact the activation and regulation of these pathways, exacerbating ischemic brain injury. Therapeutic approaches targeting the UPS in cerebral ischemia aim to rebalance protein levels, reduce proteotoxic stress, and mitigate neuronal injury. Strategies include proteasome inhibition, targeting specific ubiquitin ligases and deubiquitinating enzymes, and modulating ubiquitination-mediated regulation of key signaling pathways implicated in ischemia-induced pathophysiology. Therefore, the present review discusses the molecular mechanisms underlying UPS dysfunction in ischemic stroke is crucial for developing effective therapeutic interventions. Modulating ubiquitination-mediated pathways through therapeutic interventions targeting specific UPS components holds significant promise for mitigating ischemic brain injury and promoting neuroprotection and functional recovery in patients with cerebral ischemia.

Endothelin-1-Induced Persistent Ischemia in a Chicken Embryo Model

Current ischemic models strive to replicate ischemia-mediated injury. However, they face challenges such as inadequate reproducibility, difficulties in translating rodent findings to humans, and ethical, financial, and practical constraints that limit the accuracy of extensive research. This study introduces a novel approach to inducing persistent ischemia in 3-day-old chicken embryos using endothelin-1. The protocol targets the right vitelline arteries, validated with Doppler blood flow imaging and molecular biology experiments. This innovative approach facilitates the exploration of oxidative stress, inflammatory responses, cellular death, and potential drug screening suitability utilizing a 3-day-old chicken embryo. Key features • This model enables the evaluation and investigation of the pathology related to persistent ischemia • This model allows for the assessment of parameters like oxidative stress, inflammation, and cellular death • This model enables quantification of molecular changes at the nucleic acid and protein levels • This model allows for the efficient screening of drugs and their targets Graphical overview.

HIF-1α knockdown attenuates inflammation and oxidative stress in ischemic stroke male rats via CXCR4/NF-κB pathway

BACKGROUND

Hypoxia inducible factor-1α (HIF-1α) is a sensitive indicator of oxygen homeostasis, of which the expression elevates following hypoxia/ischemia. This study reveals the specific mechanisms underlying the effects of HIF-1α on ischemic stroke (IS).

METHODS

IS model was established using middle cerebral artery occlusion (MCAO)-modeled male rats and oxygen glucose deprivation/reoxygenation (OGD/R)-treated mice hippocampal cells HT22, followed by the silencing of HIF-1α and the overexpression of C-X-C motif chemokine receptor 4 (CXCR4) and nuclear factor-kappa B (NF-κB). Following the surgery, Garcia's grading scale was applied for neurological evaluation. Cerebral infarcts and injuries were visualized using 2,3,5-triphenyltetrazolium chloride and hematoxylin-eosin staining. The levels of tumor necrosis factor-α, Interleukin (IL)-6, IL-1β, malondialdehyde, and 8-hydroxy-2'-deoxyguanosine, were calculated via ELISA. MTT assay and lactate dehydrogenase (LDH) assay kit were adopted to determine the viability and cytotoxicity of OGD/R-modeled cells. Reactive oxygen species (ROS) generation was evaluated using a 2'-7'dichlorofluorescin diacetate (DCFH-DA) probe. The levels of HIF-1α, CXCR4, and NF-κB p65 were quantified via Western blot and immunofluorescence, respectively.

RESULTS

HIF-1α knockdown improved Garcia's score, attenuated the cerebral infarct, inflammation, and ROS generation, and alleviated the levels of inflammatory cytokines and CXCR4/NF-κB p65 in MCAO-modeled rats. Such effects were reversed following the overexpression of CXCR4 and NF-κB. Also, in OGD/R-treated HT22 cells, HIF-1α silencing diminished the cytotoxicity and ROS production and reduced the expressions of CXCR4/NF-κB p65, while promoting viability. However, CXCR4/NF-κB p65 overexpression did the opposite.

CONCLUSION

HIF-1α knockdown alleviates inflammation and oxidative stress in IS through the CXCR4/NF-κB pathway.

Systems-level computational modeling in ischemic stroke: from cells to patients

Ischemic stroke, a significant threat to human life and health, refers to a class of conditions where brain tissue damage is induced following decreased cerebral blood flow. The incidence of ischemic stroke has been steadily increasing globally, and its disease mechanisms are highly complex and involve a multitude of biological mechanisms at various scales from genes all the way to the human body system that can affect the stroke onset, progression, treatment, and prognosis. To complement conventional experimental research methods, computational systems biology modeling can integrate and describe the pathogenic mechanisms of ischemic stroke across multiple biological scales and help identify emergent modulatory principles that drive disease progression and recovery. In addition, by running virtual experiments and trials in computers, these models can efficiently predict and evaluate outcomes of different treatment methods and thereby assist clinical decision-making. In this review, we summarize the current research and application of systems-level computational modeling in the field of ischemic stroke from the multiscale mechanism-based, physics-based and omics-based perspectives and discuss how modeling-driven research frameworks can deliver insights for future stroke research and drug development.

Detrimental Roles of Hypoxia-Inducible Factor-1α in Severe Hypoxic Brain Diseases

Hypoxia stabilizes hypoxia-inducible factors (HIFs), facilitating adaptation to hypoxic conditions. Appropriate hypoxia is pivotal for neurovascular regeneration and immune cell mobilization. However, in central nervous system (CNS) injury, prolonged and severe hypoxia harms the brain by triggering neurovascular inflammation, oxidative stress, glial activation, vascular damage, mitochondrial dysfunction, and cell death. Diminished hypoxia in the brain improves cognitive function in individuals with CNS injuries. This review discusses the current evidence regarding the contribution of severe hypoxia to CNS injuries, with an emphasis on HIF-1α-mediated pathways. During severe hypoxia in the CNS, HIF-1α facilitates inflammasome formation, mitochondrial dysfunction, and cell death. This review presents the molecular mechanisms by which HIF-1α is involved in the pathogenesis of CNS injuries, such as stroke, traumatic brain injury, and Alzheimer's disease. Deciphering the molecular mechanisms of HIF-1α will contribute to the development of therapeutic strategies for severe hypoxic brain diseases.

Serum erythropoietin in acute ischemic stroke: preliminary findings

Ischemic stroke is the most common stroke, caused by occlusion of cerebral vessels and leading causes of disability. Erythropoietin (EPO) has non-hematopoietic effects as a neuroprotectant after ischemic event. This study aimed to learn the serum level of EPO in acute ischemic stroke. This cross-sectional study of ischemic stroke patients with onset < 24 h and consecutive sampling was used to collect the data from medical records review, physical examinations, head CT, 24-h EPO, 24-h and seventh-day NIHSS. A total of 47 patients consisting of 59.6% women, with a median age of 53 years old (21-70). The median 24 h EPO level was 808.6 pg/mL (134.2-2988.9). The relationship between 24 h-EPO and 24-h NIHSS were not significant (r = 0.101; p = 0.250), nor to 7th day NIHSS (r =  - 0.0174; p = 0.121) and to delta NIHSS (r = 0.186; p = 0.106). The relationship of blood collection time (hour) and EPO was significant (r =  - 0.260; p = 0.039). There was a statistically significant difference between serum EPO levels in ischemic stroke patients with lacunar stroke compared to non-lacunar stroke (288.5 vs. 855.4 ng/mL; p = 0.021). There was a relationship between the time of collection of blood and the level of EPO and also there was difference EPO level in lacunar stroke subtype compared with non-lacunar. The relationship between EPO and NIHSS lost significance after analysis. There is a need for a future study comparing each stroke risk factor and the same blood collection time.

The mechanisms of Huangqi Guizhi Wuwu decoction in treating ischaemic stroke based on network pharmacology and experiment verification

CONTEXT

Huangqi Guizhi Wuwu Decoction (HGWD) is effective in treating ischaemic stroke (IS). However, its mechanism of action is still unclear.

OBJECTIVE

Network pharmacology integrated with in vivo experiments were used to clarify the underlying mechanisms of HGWD for treating IS.

MATERIALS AND METHODS

TCMSP, GeneCards, OMIM and STRING were used to retrieve and construct visual protein interaction networks for the key targets. The AutoDock tool was used for molecular docking between key targets and active compounds. The neuroprotective effect of HGWD were verified in a middle cerebral artery occlusion (MCAO) model rat. The Sprague-Dawley (SD) rats were divided into sham, model, low-dose (5 g/kg, i.g.), high-dose (20 g/kg, i.g.), and nimodipine (20 mg/kg, i.g.) groups once daily for 7 days. The neurological scores, brain infarct volumes, lipid peroxidation, inflammatory cytokines, Nissl bodies, apoptotic neurons, and signalling pathways were all investigated and evaluated in vivo.

RESULTS

Network pharmacology identified 117 HGWD targets related to IS and 36 candidate compounds. GO and KEGG analyses showed that HGWD anti-IS effects were mainly associated with PI3K-Akt and HIF-1 signalling pathways. HGWD effectively reduced the cerebral infarct volumes (19.19%), the number of apoptotic neurons (16.78%), and the release of inflammatory cytokines, etc. in MCAO rats. Furthermore, HGWD decreased the levels of HIF-1A, VEGFA, Bax, cleaved caspase-3, p-MAPK1, and p-c-Jun while increasing the expression of p-PI3K, p-AKT1, and Bcl-2.

DISCUSSION AND CONCLUSION

This study initially elucidated the mechanism of HGWD anti-IS, which contributed to the further promotion and secondary development of HGWD in clinical practice.

Phosphodiesterase 10A Is a Critical Target for Neuroprotection in a Mouse Model of Ischemic Stroke

Phosphodiesterase 10A (PDE10A) hydrolyzes adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP). It is highly expressed in the striatum. Recent evidence implied that PDE10A may be involved in the inflammatory processes following injury, such as ischemic stroke. Its role in ischemic injury was unknown. Herein, we exposed mice to 90 or 30-min middle cerebral artery occlusion, followed by the delivery of the highly selective PDE10A inhibitor TAK-063 (0.3 mg/kg or 3 mg/kg) immediately after reperfusion. Animals were sacrificed after 24 or 72 h, respectively. Both TAK-063 doses enhanced neurological function, reduced infarct volume, increased neuronal survival, reduced brain edema, and increased blood-brain barrier integrity, alongside cerebral microcirculation improvements. Post-ischemic neuroprotection was associated with increased phosphorylation (i.e., activation) of pro-survival Akt, Erk-1/2, GSK-3α/β and anti-apoptotic Bcl-xL abundance, decreased phosphorylation of pro-survival mTOR, and HIF-1α, MMP-9 and pro-apoptotic Bax abundance. Interestingly, PDE10A inhibition reduced inflammatory cytokines/chemokines, including IFN-γ and TNF-α, analyzed by planar surface immunoassay. In addition, liquid chromatography-tandem mass spectrometry revealed 40 proteins were significantly altered by TAK-063. Our study established PDE10A as a target for ischemic stroke therapy.

MicroRNA-424 alleviates neurocyte injury by targeting PDCD4 in a cellular model of cerebral ischemic stroke

Cerebral ischemic stroke is the primary cause of stroke-associated mortality and disability, and current therapeutic options are limited and ineffective. The present study aimed to investigate the potential of apoptotic therapy and the role of microRNA (miR)-424 in cerebral ischemic stroke. PC12 cells, a cloned cell line from rat adrenal pheochromocytoma, were treated with CoCl₂ to construct a cellular ischemia model. mRNA and protein levels of programmed cell death protein 4 (PDCD4), Bcl-2, Bax, caspase-3, PI3K and AKT were evaluated using reverse transcription-quantitative PCR and western blot analyses, respectively. Cell Counting Kit-8 assays were performed to examine cell viability in the ischemia model. Flow cytometry was conducted to evaluate the apoptosis of ischemic cells. Furthermore, a luciferase assay was performed to verify the target gene of miR-424. It was revealed that the expression level of miR-424 was downregulated in the ischemia model, while the expression of PDCD4 was upregulated. Moreover, the expression of miR-424 was increased after treatment with miR-424 mimics. The mRNA and protein expression of PDCD4 was upregulated after transfection with pcDNA3.1-PDCD4. PDCD4 was predicted and demonstrated to be a target of miR-424. Notably, overexpression of miR-424 increased cell viability and inhibited apoptosis in the ischemia model, which was reversed by co-treatment with pcDNA3.1-PDCD4. Furthermore, overexpression of miR-424 regulated the expression of PDCD4, Bax, Bcl-2, phosphorylated-PI3K/AKT and caspase-3, which was restored after co-transfection with pcDNA3.1-PDCD4. Collectively, the results indicated that miR-424 regulated the progression of cerebral ischemic stroke in a cellular model by targeting PDCD4.

Hypoxia Inducible Factors as Central Players in the Pathogenesis and Pathophysiology of Cardiovascular Diseases

Cardiovascular (CV) diseases are the major cause of death in industrialized countries. The main function of the CV system is to deliver nutrients and oxygen to all tissues. During most CV pathologies, oxygen and nutrient delivery is decreased or completely halted. Several mechanisms, including increased oxygen transport and delivery, as well as increased blood flow are triggered to compensate for the hypoxic state. If the compensatory mechanisms fail to sufficiently correct the hypoxia, irreversible damage can occur. Thus, hypoxia plays a central role in the pathogenesis and pathophysiology of CV diseases. Hypoxia inducible factors (HIFs) orchestrate the gene transcription for hundreds of proteins involved in erythropoiesis, glucose transport, angiogenesis, glycolytic metabolism, reactive oxygen species (ROS) handling, cell proliferation and survival, among others. The overall regulation of the expression of HIF-dependent genes depends on the severity, duration, and location of hypoxia. In the present review, common CV diseases were selected to illustrate that HIFs, and proteins derived directly or indirectly from their stabilization and activation, are related to the development and perpetuation of hypoxia in these pathologies. We further classify CV diseases into acute and chronic hypoxic states to better understand the temporal relevance of HIFs in the pathogenesis, disease progression and clinical outcomes of these diseases. We conclude that HIFs and their derived factors are fundamental in the genesis and progression of CV diseases. Understanding these mechanisms will lead to more effective treatment strategies leading to reduced morbidity and mortality.

Circulating lncRNAs HIF1A-AS2 and LINLK-A: Role and Relation to Hypoxia-Inducible Factor-1α in Cerebral Stroke Patients

Long noncoding RNAs (lncRNAs) have been recently recognized as key players of gene expression in cerebral pathogenesis. Thus, their potential use in stroke diagnosis, prognosis, and therapy is actively pursued. Due to the complexity of the disease, identifying stroke-specific lncRNAs remains a challenge. This study investigated the expression of lncRNAs HIF1A-AS2 and LINK-A, and their target gene hypoxia-inducible factor-1 (HIF-1) in Egyptian stroke patients. It also aimed to determine the molecular mechanism implicated in the disease. A total of 75 stroke patients were divided into three clinical subgroups, besides 25 healthy controls of age-matched and sex-matched. Remarkable upregulation of lncRNA HIF1A-AS2 and HIF1-α along with a downregulation of lncRNA LINK-A was noticed in all stroke groups relative to controls. Serum levels of phosphatidylinositol 3-kinase (PI3K), phosphorylated-Akt (p-Akt), vascular endothelial growth factor (VEGF), and angiopoietin-1 (ANG1) as well as their receptors, malondialdehyde (MDA), and total antioxidant capacity (TAC) were significantly increased, whereas brain-derived neurotrophic factor (BDNF) levels were significantly decreased particularly in hemorrhagic stroke versus ischemic groups. Eventually, these findings support the role of lncRNAs HIF1A-AS2 and LINK-A as well as HIF1-α in activation of angiogenesis, neovascularization, and better prognosis of stroke, especially the hemorrhagic type.

Pulsed Electromagnetic Fields Stimulate HIF-1α-Independent VEGF Release in 1321N1 Human Astrocytes Protecting Neuron-Like SH-SY5Y Cells from Oxygen-Glucose Deprivation

Pulsed electromagnetic fields (PEMFs) are emerging as an innovative, non-invasive therapeutic option in different pathological conditions of the central nervous system, including cerebral ischemia. This study aimed to investigate the mechanism of action of PEMFs in an in vitro model of human astrocytes, which play a key role in the events that occur following ischemia. 1321N1 cells were exposed to PEMFs or hypoxic conditions and the release of relevant neurotrophic and angiogenic factors, such as VEGF, EPO, and TGF-β1, was evaluated by means of ELISA or AlphaLISA assays. The involvement of the transcription factor HIF-1α was studied by using the specific inhibitor chetomin and its expression was measured by flow cytometry. PEMF exposure induced a time-dependent, HIF-1α-independent release of VEGF from 1321N1 cells. Astrocyte conditioned medium derived from PEMF-exposed astrocytes significantly reduced the oxygen-glucose deprivation-induced cell proliferation and viability decrease in the neuron-like cells SH-SY5Y. These findings contribute to our understanding of PEMFs action in neuropathological conditions and further corroborate their therapeutic potential in cerebral ischemia.