Imperatorin inhibits mitogen-activated protein kinase and nuclear factor kappa-B signaling pathways and alleviates neuroinflammation in ischemic stroke

Neutrophil extracellular traps mediate neuro-immunothrombosis

Neutrophil extracellular traps are primarily composed of DNA and histones and are released by neutrophils to promote inflammation and thrombosis when stimulated by various inflammatory reactions. Neutrophil extracellular trap formation occurs through lytic and non-lytic pathways that can be further classified by formation mechanisms. Histones, von Willebrand factor, fibrin, and many other factors participate in the interplay between inflammation and thrombosis. Neuro-immunothrombosis summarizes the intricate interplay between inflammation and thrombosis during neural development and the pathogenesis of neurological diseases, providing cutting-edge insights into post-neurotrauma thrombotic events. The blood-brain barrier defends the brain and spinal cord against external assaults, and neutrophil extracellular trap involvement in blood-brain barrier disruption and immunothrombosis contributes substantially to secondary injuries in neurological diseases. Further research is needed to understand how neutrophil extracellular traps promote blood-brain barrier disruption and immunothrombosis, but recent studies have demonstrated that neutrophil extracellular traps play a crucial role in immunothrombosis, and identified modulators of neuro-immunothrombosis. However, these neurological diseases occur in blood vessels, and the mechanisms are unclear by which neutrophil extracellular traps penetrate the blood-brain barrier to participate in immunothrombosis in traumatic brain injury. This review discusses the role of neutrophil extracellular traps in neuro-immunothrombosis and explores potential therapeutic interventions to modulate neutrophil extracellular traps that may reduce immunothrombosis and improve traumatic brain injury outcomes.

Oxyimperatorin attenuates LPS-induced microglial activation in vitro and in vivo via suppressing NF-κB p65 signaling

BACKGROUND

Microglia-mediated neuroinflammation is an important pathological feature in many neurological diseases; thus, suppressing microglial activation is considered a possible therapeutic strategy for reducing neuronal damage. Oxyimperatorin (OIMP) is a member of furanocoumarin, isolated from the medicinal herb Glehnia littoralis. However, it is unknown whether OIMP can suppress the neuroinflammation.

PURPOSE

To investigate the neuroprotective activity of oxyimperatorin (OIMP) in LPS-induced neuroinflammation in vitro and in vivo models.

METHODS

In vitro inflammation-related assays were performed with OIMP in LPS-induced BV-2 microglia. In addition, intraperitoneal injection of LPS-induced microglial activation in the mouse brain was used to validate the anti-neuroinflammatory activity of OIMP.

RESULTS

OIMP was found to suppress LPS-induced neuroinflammation in vitro and in vivo. OIMP significantly attenuated LPS-induced the production of free radicals, inducible nitric oxide synthase, cyclooxygenase-2, and pro-inflammatory cytokines in BV-2 microglia without causing cytotoxicity. In addition, OIMP could reduce the M1 pro-inflammatory transition in LPS-stimulated BV-2 microglia. The mechanistic study revealed that OIMP inhibited LPS-induced NF-κB p65 phosphorylation and nuclear translocation. However, OIMP did not affect LPS-induced IκB phosphorylation and degradation. In addition, OIMP also was able to reduce LPS-induced microglial activation in mice brain.

CONCLUSION

Our findings suggest that OIMP suppresses microglia activation and attenuates the production of pro-inflammatory mediators and cytokines via inhibition of NF-κB p65 signaling.

AZD1390, an ataxia telangiectasia mutated inhibitor, attenuates microglia-mediated neuroinflammation and ischemic brain injury

AIMS

Excessive neuroinflammation mediated mainly by microglia plays a crucial role in ischemic stroke. AZD1390, an ataxia telangiectasia mutated (ATM) specific inhibitor, has been shown to promote radio-sensitization and survival in central nervous system malignancies, while the role of AZD1390 in ischemic stroke remains unknown.

METHODS

Real-time PCR, western blot, immunofluorescence staining, flow cytometry and enzyme-linked immunosorbent assays were used to assess the activation of microglia and the release of inflammatory cytokines. Behavioral tests were performed to measure neurological deficits. 2,3,5-Triphenyltetrazolium chloride staining was conducted to assess the infarct volume. The activation of NF-κB signaling pathway was explored through immunofluorescence staining, western blot, co-immunoprecipitation and proximity ligation assay.

RESULTS

The level of pro-inflammation cytokines and activation of NF-κB signaling pathway was suppressed by AZD1390 in vitro and in vivo. The behavior deficits and infarct size were partially restored with AZD1390 treatment in experimental stroke. AZD1390 restrict ubiquitylation and sumoylation of the essential regulatory subunit of NF-κB (NEMO) in an ATM-dependent and ATM-independent way respectively, which reduced the activation of the NF-κB pathway.

CONCLUSION

AZD1390 suppressed NF-κB signaling pathway to alleviate ischemic brain injury in experimental stroke, and attenuated microglia activation and neuroinflammation, which indicated that AZD1390 might be an attractive agent for the treatment of ischemic stroke.

Neuroprotective effects of Aucubin against cerebral ischemia-reperfusion injury

AIMS

To study the role of Aucubin (AU) in cerebral ischemia-reperfusion injury and investigate the potential mechanisms.

METHODS

For the in vitro experiment, primary microglia were cultured and stimulated by Lipopolysaccharides (LPS) and treated with AU. Male C57/BL6J mice were used and middle cerebral artery occlusion (MCAO) model was performed to induce cerebral ischemia-reperfusion injury. For the short-term effects, mice administrated with AU (40 mg/kg) for 3 days after MCAO were evaluated for the infarct volume and neurological deficits. The neuroinflammatory factors and microglia activation were determined by Real-time PCR, western blot and immunofluorescence staining. For the long-term effects, MCAO mice were injected daily with AU (5 mg/kg or 10 mg/kg) for 28 days. Behavior tests were used to assess the neurological deficits of MCAO mice, and white matter integrity was determined by myelin basic protein (MBP) staining and black-gold staining.

RESULTS

AU suppressed LPS-induced activation of microglia and pro-inflammatory cytokines release, and downregulated the NF-κB and MAPK pathways in primary microglia. In addition, AU attenuated ischemic injury and inhibited the neuro-inflammatory response in MCAO mice. Moreover, AU induced prolonged improvements in sensorimotor function and memory function following MCAO, and preserved white matter integrity in the long-term experiments.

CONCLUSIONS

AU protected against ischemic injury, which might be correlated with the downregulation of NF-κB and MAPK signaling pathways. Furthermore, AU alleviated cognitive impairment after stroke and restored white matter integrity. Our data indicated that AU might be a potential compound for the treatment of stroke and post-stroke cognitive impairment.

Influence of the brain‑gut axis on neuroinflammation in cerebral ischemia‑reperfusion injury (Review)

Stroke, a debilitating cerebrovascular ailment, poses significant threats to human life and health. The intricate interplay between the gut‑brain‑microbiota axis (GBMA) and cerebral ischemia‑reperfusion has increasingly become a focal point of scientific exploration, emerging as a pivotal research avenue in stroke pathophysiology. In the present review, the authors delved into the nexus between the GBMA and neuroinflammation observed post‑stroke. The analysis underscored the pivotal roles of histone deacetylase 3 and neutrophil extracellular traps subsequent to stroke incidents. The influence of gut microbial compositions and their metabolites, notably short‑chain fatty acids and trimethylamine N‑oxide, on neuroinflammatory processes, was further elucidated. The involvement of immune cells, especially regulatory T‑cells, and the intricate signaling cascades including cyclic GMP‑AMP synthase/stimulator of interferon genes/Toll‑like receptor, further emphasized the complex regulatory mechanisms of GBMA in cerebral ischemia/reperfusion injury (CI/RI). Collectively, the present review offered a comprehensive perspective on the metabolic, immune and inflammatory modulations orchestrated by GBMA, augmenting the understanding of its role in neuroinflammation following CI/RI.

The cell-specific roles of Nrf2 in acute and chronic phases of ischemic stroke

Ischemic stroke refers to the sudden loss of blood flow in a specific area of the brain. It is the fifth leading cause of mortality and the leading cause of permanent disability. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) controls the production of several antioxidants and protective proteins and it has been investigated as a possible pharmaceutical target for reducing harmful oxidative events in brain ischemia. Each cell type exhibits different roles and behaviors in different phases post-stroke, which is comprehensive yet important to understand to optimize management strategies and goals for care for stroke patients. In this review, we comprehensively summarize the protective effects of Nrf2 in experimental ischemic stroke, emphasizing the role of Nrf2 in different cell types including neurons, astrocytes, oligodendrocytes, microglia, and endothelial cells during acute and chronic phases of stroke and providing insights on the neuroprotective role of Nrf2 on each cell type throughout the long term of stroke care. We also highlight the importance of targeting Nrf2 in clinical settings while considering a variety of important factors such as age, drug dosage, delivery route, and time of administration.

Imperatorin inhibits oxidative stress injury and neuroinflammation via the PI3K/AKT signaling pathway in the MPTP-induced Parkinson's disease mouse

Parkinson's disease (PD) is a disorder of neurodegeneration. Imperatorin is an active natural furocoumarin characterized by antioxidant, anti-inflammatory, and potent vasodilatory properties. Therefore, we aimed to investigate the biological functions of imperatorin and its mechanisms against PD progression. C57BL/6 mice were intraperitoneally injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 30 mg/kg) daily for 5 consecutive days to mimic PD conditions in vivo. The MPTP-induced PD model mice were intraperitoneally injected with imperatorin (5 mg/kg) for 25 consecutive days after MPTP administration. The motor and cognitive functions of mice were examined by rotarod test, hanging test, narrow beam test and Morris water maze test. After analysis of MWM test, the expression levels of tyrosine hydroxylase and Iba-1 in the substantia nigra pars compacta were measured by immunohistochemistry staining, immunofluorescence staining and western blotting. The expression levels of striatal dopamine and its metabolite 3,4-dihydroxyphenylacetic acid were also measured. The protein levels of inducible nitric-oxide synthase, cyclooxygenase-2, phosphorylated phosphatidylinositol 3-kinase (PI3K) and phosphorylated protein kinase B (Akt) in the mouse striatum were estimated by western blotting. The expression levels of proinflammatory cytokines including tumor necrosis factor, interleukin (IL)-1β and IL-6 in the mouse striatum were measured by ELISA kits. The expression levels of superoxide dismutase, malondialdehyde and glutathione in the mouse midbrains were measured with commercially available kits. TUNEL staining was performed to identify the apoptosis of midbrain cells. Histopathologic changes in the mouse striata were assessed by hematoxylin-eosin staining. Imperatorin treatment markedly improved spatial learning and memory abilities of MPTP-induced PD mice. The MPTP-induced dopaminergic neuron loss in the mouse striata was inhibited by imperatorin. Imperatorin also suppressed neuroinflammation and neuronal oxidative stress in the midbrains of MPTP-induced PD mice. Mechanistically, imperatorin treatment inhibited the MPTP-induced reduction in the PI3K/Akt pathway. Imperatorin treatment can prevent dopaminergic neuron degeneration and improve cognitive functions via its potent antioxidant and anti-inflammatory properties in an MPTP-induced PD model in mice by regulating the PI3K/Akt pathway.

Negative regulation of angiogenesis and the MAPK pathway may be a shared biological pathway between IS and epilepsy

Ischemia stroke and epilepsy are two neurological diseases that have significant patient and societal burden, with similar symptoms of neurological deficits. However, the underlying mechanism of their co-morbidity are still unclear. In this study, we performed a combined analysis of six gene expression profiles (GSE58294, GSE22255, GSE143272, GSE88723, GSE163654, and GSE174574) to reveal the common mechanisms of IS and epilepsy. In the mouse datasets, 74 genes were co-upregulated and 7 genes were co-downregulated in the stroke and epilepsy groups. Further analysis revealed that the co-expressed differentially expressed genes (DEGs) were involved in negative regulation of angiogenesis and the MAPK signaling pathway, and this was verified by Gene Set Enrichment Analysis of human datasets and single cell RNA sequence of middle cerebral artery occlusion mice. In addition, combining DEGs of human and mouse, PTGS2, TMCC3, KCNJ2, and GADD45B were identified as cross species conserved hub genes. Meanwhile, molecular docking results revealed that trichostatin A and valproic acid may be potential therapeutic drugs. In conclusion, to our best knowledge, this study conducted the first comorbidity analysis of epilepsy and ischemic stroke to identify the potential common pathogenic mechanisms and drugs. The findings may provide an important reference for the further studies on post-stroke epilepsy.

Neuroprotective Effects of Phenolic Antioxidant Tert-butylhydroquinone (tBHQ) in Brain Diseases

Human life and health are gravely threatened by brain diseases. The onset and progression of the illnesses are influenced by a variety of factors, including pathogenic causes, environmental factors, mental issues, etc. According to scientific studies, neuroinflammation and oxidative stress play a significant role in the development and incidence of brain diseases by producing pro-inflammatory cytokines and oxidative tissue damage to induce inflammation and apoptosis. Neuroinflammation, oxidative stress, and oxidative stress-related changes are inseparable factors in the etiology of several brain diseases. Numerous neurodegenerative diseases have undergone substantial research into the therapeutic alternatives that target oxidative stress, the function of oxidative stress, and the possible therapeutic use of antioxidants. Formerly, tBHQ is a synthetic phenolic antioxidant, which has been widely used as a food additive. According to recent researches, tBHQ can suppress the processes that lead to neuroinflammation and oxidative stress, which offers a fresh approach to treating brain diseases. In order to achieve the goal of decreasing inflammation and apoptosis, tBHQ is a specialized nuclear factor erythroid 2-related factor (Nrf2) activator that decreases oxidative stress and enhances antioxidant status by upregulating the Nrf2 gene and reducing nuclear factor kappa-B (NF-κB) activity. This article reviews the effects of tBHQ on neuroinflammation and oxidative stress in recent years and looks into how tBHQ inhibits neuroinflammation and oxidative stress through human, animal, and cell experiments to play a neuroprotective role in Alzheimer's disease (AD), stroke, depression, and Parkinson's disease (PD). It is anticipated that this article will be useful as a reference for upcoming research and the creation of drugs to treat brain diseases.

Hogweed Seed Oil: Physico-Chemical Characterization, LC-MS Profile, and Neuroprotective Activity of Heracleum dissectum Nanosuspension

The seeds of dissected hogweed (Heracleum dissectum Ledeb., Apiaceae) are the source of hogweed oil (HSO), which is still underexplored and requires careful chemical and biological studies. The performed physico-chemical analysis of HSO elucidated basic physical characteristics and revealed the presence of fatty acids, essential oil components, pigments, and coumarins. High-performance liquid chromatography with photodiode array detection and electrospray ionization triple quadrupole mass spectrometric detection (HPLC-PDA-ESI-tQ-MS/MS) identified 38 coumarins that were characterized and quantified. Various furanocoumarins were the major components of HSO polyphenolics, including imperatorin, phellopterin, and isoimperatorin, and the total coumarin content in HSO varied from 181.14 to 238.42 mg/mL. The analysis of storage stability of the selected compounds in HSO indicated their good preservation after 3-year storage at cold and freezing temperatures. The application of the CO₂-assisted effervescence method allowed the production of an HSO nanosuspension, which was used in a brain ischemia model of rats. The HSO nanosuspension enhanced cerebral hemodynamics and decreased the frequency of necrotic processes in the brain tissue. Thus, H. dissectum seeds are a good source of coumarins, and HSO nanosuspension promotes neuroprotection of the brain after lesions, which supports earlier ethnopharmacological data.

High-Mobility Group Box 1 in Spinal Cord Injury and Its Potential Role in Brain Functional Remodeling After Spinal Cord Injury

High-mobility group box 1 (HMGB1) is a nonhistone nuclear protein, the functions of which depend on its subcellular location. It is actively or passively secreted into the blood and/or cerebrospinal fluid (CSF) and can be used as a prognostic indicator of disease. HMGB1 released into the bloodstream can cause pathological reactions in distant organs, and entry into the CSF can destroy the blood-brain barrier and aggravate brain injuries. HMGB1 expression has been reported to be increased in the tissues of spinal cord injury (SCI) patients and involved in the regulation of neuroinflammation, neuronal apoptosis, and ferroptosis. SCI can lead to brain changes, resulting in neuropathic pain, depression, and cognitive dysfunction, but the specific mechanism is unknown. It remains unclear whether HMGB1 plays an important role in brain functional remodeling after SCI. Damaged cells at the site of SCI passively release HMGB1, which travels to the brain via the blood, CSF, and/or axonal transport, destroys the blood-brain barrier, and causes pathological changes in the brain. This may explain the remodeling of brain function that occurs after SCI. In this minireview, we introduce the structure and function of HMGB1 and its mechanism of action in SCI. Clarifying the functions of HMGB1 may provide insight into the links between SCI and various brain regions.

Imperatorin Positively Regulates Melanogenesis through Signaling Pathways Involving PKA/CREB, ERK, AKT, and GSK3β/β-Catenin

The present study investigated the melanogenic effects of imperatorin and isoimperatorin and the underlying mechanisms of imperatorin using a mouse melanoma B16F10 model. Interestingly, treatment with 25 μM of either imperatorin or isoimperatorin, despite their structural differences, did not produce differences in melanin content and intracellular tyrosinase activity. Imperatorin also activated the expression of melanogenic enzymes, such as tyrosinase (TYR) and tyrosinase-related proteins TYRP-1 and TYRP-2. Mechanistically, imperatorin increases melanin synthesis through the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA)/cAMP-responsive element-binding protein (CREB)-dependent upregulation of microphthalmia-associated transcription factor (MITF), which is a key transcription factor in melanogenesis. Furthermore, imperatorin exerted melanogenic effects by downregulating extracellular signal-regulated kinase (ERK) and upregulating phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT)/glycogen synthesis kinase-3β (GSK-3β). Moreover, imperatorin increased the content of β-catenin in the cell cytoplasm and nucleus by reducing the content of phosphorylated β-catenin (p-β-catenin). Finally, we tested the potential of imperatorin in topical application through primary human skin irritation tests. These tests were performed on the normal skin (upper back) of 31 volunteers to determine whether 25 or 50 µM of imperatorin had irritation or sensitization potential. During these tests, imperatorin did not induce any adverse reactions. Taken together, these findings suggest that the regulation of melanogenesis by imperatorin can be mediated by signaling pathways involving PKA/CREB, ERK, AKT, and GSK3β/β-catenin and that imperatorin could prevent the pathogenesis of pigmentation diseases when used as a topical agent.

Trehalose-Carnosine Prevents the Effects of Spinal Cord Injury Through Regulating Acute Inflammation and Zinc(II) Ion Homeostasis

Spinal cord injury (SCI) leads to long-term and permanent motor dysfunctions, and nervous system abnormalities. Injury to the spinal cord triggers a signaling cascade that results in activation of the inflammatory cascade, apoptosis, and Zn(II) ion homeostasis. Trehalose (Tre), a nonreducing disaccharide, and L-carnosine (Car), (β-alanyl-L-histidine), one of the endogenous histidine dipeptides have been recognized to suppress early inflammatory effects, oxidative stress and to possess neuroprotective effects. We report on the effects of the conjugation of Tre with Car (Tre-car) in reducing inflammation in in vitro and in vivo models. The in vitro study was performed using rat pheochromocytoma cells (PC12 cell line). After 24 h, Tre-car, Car, Tre, and Tre + Car mixture treatments, cells were collected and used to investigate Zn²⁺ homeostasis. The in vivo model of SCI was induced by extradural compression of the spinal cord at the T6-T8 levels. After treatments with Tre, Car and Tre-Car conjugate 1 and 6 h after SCI, spinal cord tissue was collected for analysis. In vitro results demonstrated the ionophore effect and chelating features of L-carnosine and its conjugate. In vivo, the Tre-car conjugate treatment counteracted the activation of the early inflammatory cascade, oxidative stress and apoptosis after SCI. The Tre-car conjugate stimulated neurotrophic factors release, and influenced Zn²⁺ homeostasis. We demonstrated that Tre-car, Tre and Car treatments improved tissue recovery after SCI. Tre-car decreased proinflammatory, oxidative stress mediators release, upregulated neurotrophic factors and restored Zn²⁺ homeostasis, suggesting that Tre-car may represent a promising therapeutic agent for counteracting the consequences of SCI.

Bergapten attenuates microglia-mediated neuroinflammation and ischemic brain injury by targeting Kv1.3 and Carbonyl reductase 1

Microglia-mediated neuroinflammation plays a vital role in the pathogenesis of ischemic stroke, which serves as a prime target for developing novel therapeutic agent. However, feasible and effective agents for controlling neuroinflammation are scarce. Bergapten were acknowledged to hold therapeutic potential in restricting inflammation in multiple diseases, including peripheral neuropathy, migraine headaches and osteoarthritis. Here, we aimed to investigate the impact of bergapten on microglia-mediated neuroinflammation and its therapeutic potential in ischemic stroke. Our study demonstrated that bergapten significantly reduced the expression of pro-inflammatory cytokines and the activation of NF-κB signaling pathway in LPS-stimulated primary microglia. Mechanistically, bergapten suppressed cellular potassium ion efflux by inhibiting Kv1.3 channel and inhibits the degradation of Carbonyl reductase 1 induced by LPS, which might contribute to the anti-inflammatory effect of bergapten. Furthermore, bergapten suppressed microglial activation and post-stroke neuroinflammation in an experimental stroke model, leading to reduced infarct size and improved functional recovery. Thus, our study identified that bergapten might be a potential therapeutic compound for the treatment of ischemic stroke.

Regulation of ferroptosis by noncoding RNAs: a novel promise treatment in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a highly prevalent tumor that requires extensive research. Ferroptosis is a unique cell death modality driven by iron-dependent phospholipid peroxidation manifested as an accumulation of lipid-reactive oxygen species. With further understanding of noncoding RNAs (ncRNAs), numerous studies have demonstrated an important regulatory role of ncRNAs in ESCC through ferroptosis, including microRNAs, long ncRNAs, and circular RNAs. These ncRNAs influence the expression of the target gene to regulate ESCC progression by involving the ferroptosis signaling pathway. However, the specific regulatory mechanism of ncRNAs on ferroptosis in ESCC remains largely unknown. This review summarized the current knowledge on the relation between ferroptosis regulators, such as glutathione synthesis/metabolism, Keap1/Nfr2, and p53, by ncRNAs and ESCC. This review also proposed the possible therapeutic approaches for ncRNAs targeting ferroptosis in ESCC. This is the latest and most effective summary of recent research achievements of ncRNAs on ferroptosis in ESCC. These ncRNAs based on ferroptosis merit further investigation in preclinical research of ESCC.