Progranulin protects against cerebral ischemia-reperfusion (I/R) injury by inhibiting necroptosis and oxidative stress

Mechanism of ferroptosis in heart failure: The role of the RAGE/TLR4-JNK1/2 pathway in cardiomyocyte ferroptosis and intervention strategies

The ferroptosis of cardiomyocytes has been recognized as the core pathological mechanism of heart failure. During the evolution of cardiovascular diseases, the accumulation of angiotensin II and advanced glycation end products can lead to the excessive activation of the RAGE/TLR4-JNK1/2 pathway, which subsequently triggers ferritinophagy, clockophagy, and enhanced p53 activity, ultimately leading to cardiomyocyte ferroptosis. It is evident that deeply unraveling the specific mechanisms in this field and comprehensively evaluating potential drugs and therapeutic strategies targeting this pathway is crucial for improving the status of cardiomyocyte ferroptosis. However, our current understanding of this pathway's specific molecular biological mechanisms in the process of cardiomyocyte ferroptosis remains limited. In light of this, this paper first comprehensively reviews the historical context of ferroptosis research, compares the similarities and differences between ferroptosis and other standard modes of cell death, elucidates the core mechanisms of ferroptosis and its close connection with heart failure, aiming to establish a basic cognitive framework for readers on ferroptosis and its role in heart failure. Subsequently, the paper delves into the pivotal role of the RAGE/TLR4-JNK1/2 pathway in cardiomyocyte ferroptosis and its intricate molecular biological regulatory network. Furthermore, it systematically integrates various therapeutic approaches aimed at inhibiting RAGE, TLR4, and JNK1/2 activity to alleviate cardiomyocyte ferroptosis, encompassing RNA interference technology, gene knockout techniques, small molecule inhibitors, natural active ingredients, as well as traditional Chinese and Western medicines, with the ultimate goal of forging new avenues and strategies for the prevention and treatment of heart failure.

Natural products and ferroptosis: A novel approach for heart failure management

BACKGROUND

The discovery of ferroptosis has brought a revolutionary breakthrough in heart failure treatment, and natural products, as a significant source of drug discovery, are gradually demonstrating their extraordinary potential in regulating ferroptosis and alleviating heart failure symptoms. In addition to chemically synthesized small molecule compounds, natural products have attracted attention as an important source for discovering compounds that target ferroptosis in treating heart failure.

PURPOSE

Systematically summarize and analyze the research progress on improving heart failure through natural products' modulation of the ferroptosis pathway.

METHODS

By comprehensively searching authoritative databases like PubMed, Web of Science, and China National Knowledge Infrastructure with keywords such as "heart failure", "cardiovascular disease", "heart disease", "ferroptosis", "natural products", "active compounds", "traditional Chinese medicine formulas", "traditional Chinese medicine", and "acupuncture", we aim to systematically review the mechanism of ferroptosis and its link with heart failure. We also want to explore natural small-molecule compounds, traditional Chinese medicine formulas, and acupuncture therapies that can inhibit ferroptosis to improve heart failure.

RESULTS

In this review, we not only trace the evolution of the concept of ferroptosis and clearly distinguish it from other forms of cell death but also establish a comprehensive theoretical framework encompassing core mechanisms such as iron overload and system xc-/GSH/GPX4 imbalance, along with multiple auxiliary pathways. On this basis, we innovatively link ferroptosis with various types of heart failure, covering classic heart failure types and extending our research to pre-heart failure conditions such as arrhythmia and aortic aneurysm, providing new insights for early intervention in heart failure. Importantly, this article systematically integrates multiple strategies of natural products for interfering with ferroptosis, ranging from monomeric compounds and bioactive components to crude extracts and further to traditional Chinese medicine formulae. In addition, non-pharmacological means such as acupuncture are also included.

CONCLUSION

This study fills the gap in the systematic description of the relationship between ferroptosis and heart failure and the therapeutic strategies of natural products, aiming to provide patients with more diverse treatment options and promote the development of the heart failure treatment field.

Lepalvir: Biomaterial efficacy and safety for patients with acute ischemic stroke

Lepalvir, derived from inflamed rabbit skin inoculated with vaccinia virus, has potential neuroprotective and anti-inflammatory effects. We conducted a phase II, multicenter, randomized, blind, placebo-controlled trial investigating the efficacy and safety of Lepalvir for acute ischemic stroke (AIS). Participants aged 18-80 years with AIS in the anterior circulation and a National Institutes of Health Stroke Scale (NIHSS) score of 4-24 within 48 h post-onset were randomized to receive high-dose (192U), low-dose (96U) Lepalvir, or saline placebo for 14 days. The primary outcome was the proportion of patients achieving a modified Rankin Scale (mRS) score ≤ 1 at day 90 (D90) post-randomization. Among 238 patients, no significant difference in mRS score at D90 was observed across groups, yet a higher percentage in the high-dose group achieved a mRS score ≤ 1 at D90, compared to the control and low-dose group. No significant safety concerns were noted. While functional improvement was not significantly different at D90, Lepalvir showed a favorable safety profile and potential at the higher dosage, warranting further phase III investigation.

Insights on the crosstalk among different cell death mechanisms

The phenomenon of cell death has garnered significant scientific attention in recent years, emerging as a pivotal area of research. Recently, novel modalities of cellular death and the intricate interplay between them have been unveiled, offering insights into the pathogenesis of various diseases. This comprehensive review delves into the intricate molecular mechanisms, inducers, and inhibitors of the underlying prevalent forms of cell death, including apoptosis, autophagy, ferroptosis, necroptosis, mitophagy, and pyroptosis. Moreover, it elucidates the crosstalk and interconnection among the key pathways or molecular entities associated with these pathways, thereby paving the way for the identification of novel therapeutic targets, disease management strategies, and drug repurposing.

Deciphering Necroptosis-Associated Molecular Subtypes in Acute Ischemic Stroke Through Bioinformatics and Machine Learning Analysis

Acute ischemic stroke (AIS) is a severe disorder characterized by complex pathophysiological processes, which can lead to disability and death. This study aimed to determine necroptosis-associated genes in acute ischemic stroke (AIS) and to investigate their potential as diagnostic and therapeutic targets for AIS. Expression profiling data were acquired from the Gene Expression Omnibus database, and necroptosis-associated genes were retrieved from GeneCards. The differentially expressed genes (DEGs) and necroptosis-related genes were intersected to obtain the necroptosis-related DEGs (NRDEGs) in AIS. In AIS, a total of 76 genes associated with necroptosis (referred to as NRDEGs) were identified. Enrichment analysis of these genes revealed that they were primarily enriched in pathways known to induce necroptosis. Using weighted gene co-expression network analysis (WGCNA), five co-expression modules consisting of NRDEGs were identified, along with two modules that exhibited a strong correlation with AIS. Protein-protein interaction (PPI) analysis resulted in the identification of 20 hub genes. The Least absolute shrinkage and selection operator (LASSO) regression model demonstrated promising potential for diagnostic prediction. The receiver operating characteristic (ROC) curve validated the diagnostic model and selected nine characteristic genes that exhibited statistically significant differences (p < 0.05). By employing consensus clustering, distinct patterns of necroptosis were identified using these nine signature genes. The results were validated by quantitative PCR (qPCR) in venous blood from patients with AIS and healthy controls and HT22 cells, as well as external datasets. Furthermore, the analyzed ceRNA network included nine lncRNAs, six miRNAs, and three mRNAs. Overall, this study offers novel insights into the molecular mechanisms underlying NRDEGs in AIS. The findings provide valuable evidence and contribute to our understanding of the disease.

PGRN protects against serum deprivation-induced cell death by promoting the ROS scavenger system in cervical cancer

Progranulin (PGRN), an autocrine growth factor with tumorigenic roles in a variety of tumors, is a putative survival factor for normal and cancer cells in vitro. However, the fundamental mechanism of PGRN-mediated survival of cancer cells suffering from various types of microenvironmental stresses, such as serum deprivation, remains unknown. We show here that serum deprivation decreases intracellular PGRN protein levels in cervical cancer cells. PGRN protects cervical cancer cells against serum deprivation-induced apoptosis, limits reactive oxygen species (ROS) levels, maintains mitochondria integrity, and reduces oxidative damage of protein, lipid and DNA. PGRN enhances the ROS scavenger system, as evidenced by increased superoxide dismutase (SOD), catalase protein expression and activity, elevated GSH and NADPH levels and increased phase II detoxification enzyme expression in cervical cancer cells after serum withdrawal. The role of PGRN in ROS clearance is mediated by the PGRN-stimulated nuclear factor erythroid-derived 2-like 2 (NFE2L2)-antioxidant response element (ARE) pathway. Our study reveals an antioxidant role of PGRN in supporting the survival of cervical cancer cells under oxidative stress. This insight provides a new perspective on the how cervical cancer cells adapt to microenvironmental stress, contributing to cell viability and other malignant characteristics.

Progranulin enhances the engraftment of transplanted human iPS cell-derived cerebral neurons

Cerebral organoids (COs) in cell replacement therapy offer a viable approach to reconstructing neural circuits for individuals suffering from stroke or traumatic brain injuries. Successful transplantation relies on effective engraftment and neurite extension from the grafts. Earlier research has validated the effectiveness of delaying the transplantation procedure by 1 week. Here, we hypothesized that brain tissues 1 week following a traumatic brain injury possess a more favorable environment for cell transplantation when compared to immediately after injury. We performed a transcriptomic comparison to differentiate gene expression between these 2 temporal states. In controlled in vitro conditions, recombinant human progranulin (rhPGRN) bolstered the survival rate of dissociated neurons sourced from human induced pluripotent stem cell-derived COs (hiPSC-COs) under conditions of enhanced oxidative stress. This increase in viability was attributable to a reduction in apoptosis via Akt phosphorylation. In addition, rhPGRN pretreatment before in vivo transplantation experiments augmented the engraftment efficiency of hiPSC-COs considerably and facilitated neurite elongation along the host brain's corticospinal tracts. Subsequent histological assessments at 3 months post-transplantation revealed an elevated presence of graft-derived subcerebral projection neurons-crucial elements for reconstituting neural circuits-in the rhPGRN-treated group. These outcomes highlight the potential of PGRN as a neurotrophic factor suitable for incorporation into hiPSC-CO-based cell therapies.

Transplantation of neural stem cells improves recovery of stroke-affected mice and induces cell-specific changes in GSDMD and MLKL expression

Introduction

Stroke, the second leading cause of death and disability in Europe, is primarily caused by interrupted blood supply, leading to ischemia-reperfusion (IR) injury and subsequent neuronal death. Current treatment options are limited, highlighting the need for novel therapies. Neural stem cells (NSCs) have shown promise in treating various neurological disorders, including stroke. However, the underlying mechanisms of NSC-mediated recovery remain unclear.

Methods

Eighty C57Bl/6-Tyrc-Brd mice underwent ischemic stroke induction and were divided into four groups: sham, stroke-affected, stroke-affected with basal cell medium injection, and stroke-affected with NSCs transplantation. NSCs, isolated from mouse embryos, were stereotaxically transplanted into the stroke-affected brains. Magnetic resonance imaging (MRI) and neurological scoring were used to assess recovery. Immunohistochemical analysis and gene expression assays were performed to evaluate pyroptosis and necroptosis markers.

Results

NSC transplantation significantly improved neurological recovery compared to control groups. In addition, although not statistically significant, NSCs reduced stroke volume. Immunohistochemical analysis revealed upregulation of Gasdermin D (GSDMD) expression post-stroke, predominantly in microglia and astrocytes. However, NSC transplantation led to a reduction in GSDMD signal intensity in astrocytes, suggesting an effect of NSCs on GSDMD activity. Furthermore, NSCs downregulated Mixed Lineage Kinase Domain-Like Protein (Mlkl) expression, indicating a reduction in necroptosis. Immunohistochemistry demonstrated decreased phosphorylated MLKL (pMLKL) signal intensity in neurons while stayed the same in astrocytes following NSC transplantation, along with increased distribution in microglia.

Discussion

NSC transplantation holds therapeutic potential in stroke recovery by targeting pyroptosis and necroptosis pathways. These findings shed light on the mechanisms underlying NSC-mediated neuroprotection and support their further exploration as a promising therapy for stroke patients.

Crosstalk between ferroptosis and necroptosis in cerebral ischemia/reperfusion injury and Naotaifang formula exerts neuroprotective effect via HSP90-GCN2-ATF4 pathway

BACKGROUND

Cerebral ischemia/reperfusion injury (CIRI) is a sequence of pathophysiological processes after blood recanalization in the patients with ischemic stroke, and has become the hinder for the rehabilitation. Naotaifang formula (NTF) has exhibited the clinical effectiveness for this disease. However, its action effects and molecular mechanisms against CIRI are not fully elucidated.

PURPOSE

The research was to clarify the crosstalk between ferroptosis and necroptosis in CIRI, and uncover the mechanism underlying the neuroprotection of NTF.

METHODS

This study established MCAO/R rat models with various reperfusion times. Western blot, transmission electron microscope, laser speckle imaging, immunofluorescence, immunohistochemistry and pathological staining were conducted to detect and analyze the obtained results. Subsequently, various NTF doses were used to intervene in MCAO/R rats, and biology experiments, such as western blot, Evans blue, immunofluorescence and immunohistochemistry, were used to analyze the efficacy of NTF doses. The effect of NTF was further clarified through in vitro experiments. Eventually, HT22 cells that suffered OGD/R were subjected to pre-treatment with plasmids overexpressing HSP90, MLKL, and GPX4 to indicate the interaction among ferroptosis and necroptosis.

RESULTS

There was a gradual increase in the Zea Longa score and cerebral infarction volume following CIRI with prolonged reperfusion. Furthermore, the expression of factors associated with pro-ferroptosis and pro-necroptosis was upregulated in the cortex and hippocampus. NTF alleviated ferroptosis and necroptosis in a dose-dependent manner, downregulated HSP90 levels, reduced blood-brain barrier permeability, and thus protected nerve cells from CIRI. The results in vitro research aligned with those of the in vivo research. HSP90 and MLKL overexpression promoted necroptosis and ferroptosis while activating the GCN2-ATF4 pathway. GPX4 overexpression had no effect on necroptosis or the associated signaling pathway. The administration of NTF alone, as well as its combination with the overexpression of HSP90, MLKL, or GPX4 plasmids, decreased the expression levels of factors associated with pro-ferroptosis and pro-necroptosis and reduced the protein levels of the HSP90-GCN2-ATF4 pathway. Moreover, the regulatory effects of the NTF alone group on GSH, ferrous iron, and GCN2 were more significant compared with those of the HSP90 overexpression combination group.

CONCLUSION

Ferroptosis and necroptosis were gradually aggravated following CIRI with prolonged reperfusion. MLKL overexpression may promote ferroptosis and necroptosis, while GPX4 overexpression may have little effect on necroptosis. HSP90 overexpression accelerated both forms of cell death via the HSP90-GCN2-ATF4 pathway. NTF alleviated ferroptosis and necroptosis to attenuate CIRI by regulating the HSP90-GCN2-ATF4 pathway. Our research provided evidence for the potential of drug development by targeting HSP90, MLKL, and GPX4 to protect against ischemic stroke.

The Role of Necroptosis in Cerebral Ischemic Stroke

Cerebral ischemia, also known as ischemic stroke, accounts for nearly 85% of all strokes and is the leading cause of disability worldwide. Due to disrupted blood supply to the brain, cerebral ischemic injury is trigged by a series of complex pathophysiological events including excitotoxicity, oxidative stress, inflammation, and cell death. Currently, there are few treatments for cerebral ischemia owing to an incomplete understanding of the molecular and cellular mechanisms. Accumulated evidence indicates that various types of programmed cell death contribute to cerebral ischemic injury, including apoptosis, ferroptosis, pyroptosis and necroptosis. Among these, necroptosis is morphologically similar to necrosis and is mediated by receptor-interacting serine/threonine protein kinase-1 and -3 and mixed lineage kinase domain-like protein. Necroptosis inhibitors have been shown to exert inhibitory effects on cerebral ischemic injury and neuroinflammation. In this review, we will discuss the current research progress regarding necroptosis in cerebral ischemia as well as the application of necroptosis inhibitors for potential therapeutic intervention in ischemic stroke.

Intermittent fasting along with hydroalcoholic extract of Centella-asiatica ameliorates sub-acute hypoxia-induced ischemic stroke in adult zebrafish

Reduced blood flow (hypoxia) to the brain is thought to be the main cause of strokes because it deprives the brain of oxygen and nutrients. An increasing amount of evidence indicates that the Centella-Asiatica (HA-CA) hydroalcoholic extract has a variety of pharmacological benefits, such as antioxidant activity, neuroprotection, anti-inflammatory qualities, and angiogenesis promotion. Intermittent fasting (IF) has neurological benefits such as anti-inflammatory properties, neuroprotective effects, and the ability to enhance neuroplasticity. The current study evaluates the combined effect of IF (for 1, 6, and 12 days) along with HA-CA (daily up to 12 days) in adult zebrafish subjected to hypoxia every 5 min for 12 days followed by behavioral (novel tank and open-field tank test), biochemical (SOD, GSH-Px, and LPO), inflammatory (IL-10, IL-1β, and TNF-α), mitochondrial enzyme activities (Complex-I, II, and IV), signaling molecules (AMPK, MAPK, GSK-3β, Nrf2), and imaging/staining (H&E, TTC, and TEM) analysis. Results show that sub-acute hypoxia promotes the behavioral alterations, and production of radical species and alters the oxidative stress status in brain tissues of zebrafish, along with mitochondrial dysfunction, neuroinflammation, and alteration of signaling molecules. Nevertheless, HA-CA along with IF significantly ameliorates these defects in adult zebrafish as compared to their effects alone. Further, imaging analysis significantly provided evidence of infarct damage along with neuronal and mitochondrial damage which was significantly ameliorated by IF and HA-CA. The use of IF and HA-CA has been proven to enhance the physiological effects of hypoxia in all dimensions.

Remote Ischemic Conditioning With Medical Management or Reperfusion Therapy for Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Remote ischemic conditioning (RIC) is a low-cost, accessible, and noninvasive neuroprotective treatment strategy, but its efficacy and safety in acute ischemic stroke are controversial. With the publication of several randomized controlled trials (RCTs) and the recent results of the RESIST trial, it may be possible to identify the patient population that may (or may not) benefit from RIC. This systematic review and meta-analysis aims to evaluate the effectiveness and safety of RIC in patients with ischemic stroke receiving different treatments by pooling data of all randomized controlled studies to date.

METHODS

We searched the PubMed, Embase, Cochrane, Elsevier, and Web of Science databases to obtain articles in all languages from inception until May 25, 2023. The primary outcome was the modified Rankin Scale (mRS) score at the specified endpoint time in the trial. The secondary outcomes were change in NIH Stroke Scale (NIHSS) and recurrence of stroke events. The safety outcomes were cardiovascular events, cerebral hemorrhage, and mortality. The quality of articles was evaluated through the Cochrane risk assessment tool. This study was registered in PROSPERO (CRD42023430073).

RESULTS

There were 7,657 patients from 22 RCTs included. Compared with the control group, patients who received RIC did not have improved mRS functional outcomes, regardless of whether they received medical management, reperfusion therapy with intravenous thrombolysis (IVT), or mechanical thrombectomy (MT). In the medical management group, patients who received RIC had decreased incidence of stroke recurrence (risk ratio 0.63, 95% CI 0.43-0.92, p = 0.02) and lower follow-up NIHSS score by 1.72 points compared with the control group (p < 0.00001). There was no increased risk of adverse events including death or cerebral hemorrhage in the IVT or medical management group.

DISCUSSION

In patients with ischemic stroke who are not eligible for reperfusion therapy, RIC did not affect mRS functional outcomes but significantly improved the NIHSS score at the follow-up endpoint and reduced stroke recurrence, without increasing the risk of cerebral hemorrhage or death. In patients who received IVT or MT, the benefit of RIC was not observed.

Fat mass and obesity associated protein inhibits neuronal ferroptosis via the FYN/Drp1 axis and alleviate cerebral ischemia/reperfusion injury

OBJECTIVES

FTO is known to be involved in cerebral ischemia/reperfusion (I/R) injury. However, its related specific mechanisms during this condition warrant further investigations. This study aimed at exploring the impacts of FTO and the FYN/DRP1 axis on mitochondrial fission, oxidative stress (OS), and ferroptosis in cerebral I/R injury and the underlying mechanisms.

METHODS

The cerebral I/R models were established in mice via the temporary middle cerebral artery occlusion/reperfusion (tMCAO/R) and hypoxia/reoxygenation models were induced in mouse hippocampal neurons via oxygen-glucose deprivation/reoxygenation (OGD/R). After the gain- and loss-of-function assays, related gene expression was detected, along with the examination of mitochondrial fission, OS- and ferroptosis-related marker levels, neuronal degeneration and cerebral infarction, and cell viability and apoptosis. The binding of FTO to FYN, m6A modification levels of FYN, and the interaction between FYN and Drp1 were evaluated.

RESULTS

FTO was downregulated and FYN was upregulated in tMCAO/R mouse models and OGD/R cell models. FTO overexpression inhibited mitochondrial fission, OS, and ferroptosis to suppress cerebral I/R injury in mice, which was reversed by further overexpressing FYN. FTO overexpression also suppressed mitochondrial fission and ferroptosis to increase cell survival and inhibit cell apoptosis in OGD/R cell models, which was aggravated by additionally inhibiting DRP1. FTO overexpression inhibited FYN expression via the m6A modification to inactive Drp1 signaling, thus reducing mitochondrial fission and ferroptosis and enhancing cell viability in cells.

CONCLUSIONS

FTO overexpression suppressed FYN expression through m6A modification, thereby subduing Drp1 activity and relieving cerebral I/R injury.

Glycosylation: A new signaling paradigm for the neurovascular diseases

A wide range of life-threatening conditions with complicated pathogenesis involves neurovascular disorders encompassing Neurovascular unit (NVU) damage. The pathophysiology of NVU is characterized by several features including tissue hypoxia, stimulation of inflammatory and angiogenic processes, and the initiation of intricate molecular interactions, collectively leading to an elevation in blood-brain barrier permeability, atherosclerosis and ultimately, neurovascular diseases. The presence of compelling data about the significant involvement of the glycosylation in the development of diseases has sparked a discussion on whether the abnormal glycosylation may serve as a causal factor for neurovascular disorders, rather than being just recruited as a secondary player in regulating the critical events during the development processes like embryo growth and angiogenesis. An essential tool for both developing new anti-ischemic therapies and understanding the processes of ischemic brain damage is undertaking pre-clinical studies of neurovascular disorders. Together with the post-translational modification of proteins, the modulation of glycosylation and its enzymes implicates itself in several abnormal activities which are known to accelerate neuronal vasculopathy. Despite the failure of the majority of glycosylation-based preclinical and clinical studies over the past years, there is a significant probability to provide neuroprotection utilizing modern and advanced approaches to target abnormal glycosylation activity at embryonic stages as well. This article focuses on a variety of experimental evidence to postulate the interconnection between glycosylation and vascular disorders along with possible treatment options.

Ferroptosis in cardiovascular disease

In the 21st century, cardiovascular disease (CVD) has become one of the leading causes of death worldwide. The prevention and treatment of CVD remain pressing scientific issues. Several recent studies have suggested that ferroptosis may play a key role in CVD. Most studies conducted thus far on ferroptosis and CVD have supported the link. Ferroptosis mediated by different signaling and metabolic pathways can lead to ischemic heart disease, myocarditis, heart failure, ischemia-reperfusion injury, and cardiomyopathy. Still, the specific mechanism of ferroptosis in CVD, the particular organ areas affected, and the stage of disease involved need to be further studied. Therefore, understanding the mechanisms regulating ferroptosis in CVD may improve disease management. Throughout this review, we summarized the mechanism of ferroptosis and its effect on the pathogenesis of CVD. We also predicted and discussed future research directions, aiming to provide new ideas and strategies for preventing and treating CVD.

METTL3-deficiency Suppresses Neural Apoptosis to Induce Protective Effects in Cerebral I/R Injury via Inhibiting RNA m6A Modifications: A Pre-clinical and Pilot Study

N6-Methyladenosine (m6A) RNA methylation involves in regulating the initiation, progression and aggravation of cerebral ischemia-reperfusion (I/R) injury, however, the detailed functions and mechanisms by which m6A drives cerebral I/R injury are not fully understood. This study found that methyltransferase-like 3 (METTL3) m6A-dependently regulated cerebral I/R injury trough regulating a novel LncRNA ABHD11-AS1/miR-1301-3p/HIF1AN/HIF-1α axis. Specifically, the middle cerebral artery occlusion (MCAO)/reperfusion mice models and glucose deprivation (OGD)/reoxygenation (RX) astrocyte cell models were respectively established, and we verified that METTL3, ABHD11-AS1 and HIF1AN were upregulated, whereas miR-1301-3p and HIF-1α were downregulated in both MCAO/reperfusion mice tissues and OGD/RX astrocytes. Mechanical experiments confirmed that METTL3 m6A dependently increased stability and expression levels of ABHD11-AS1, and elevated ABHD11-AS1 sponged miR-1301-3p to upregulate HIF1AN, resulting in the downregulation of HIF-1α. Moreover, silencing of METTL3 rescued MCAO/reperfusion and OGD/RX-induced oxidative stress-associated cell apoptosis and cell cycle arrest in both mice brain tissues in vivo and the mouse primary astrocytes in vitro, which were abrogated by overexpressing ABHD11-AS1 and downregulating miR-1301-3p. Taken together, our study firstly reported a novel METTL3/m6A/ ABHD11-AS1/miR-1301-3p/HIF1AN/HIF-1α signaling cascade in regulating the progression of cerebral I/R injury, and future work will focus on investigating whether the above genes can be used as biomarkers for the treatment of cerebral I/R injury by performing clinical studies.

Nrf2/HO-1 blocks TXNIP/NLRP3 interaction via elimination of ROS in oxygen-glucose deprivation-induced neuronal necroptosis

Acute ischemic stroke (AIS) is known to trigger a cascade of inflammatory events that induces secondary tissue damages. As a type of regulated inflammatory cell death, necroptosis is associated with AIS, whilst its regulation during neuroinflammation is not well understood. In particular, the actual function of NOD-like-receptor family pyrin domain-containing-3(NLRP3) inflammasome in cortical neuronal necroptosis still not clear. Herein, we explored the function of nuclear factor erythroid-2 related factor-2 (Nrf2)/heme oxygenase-1 (HO-1) in oxygen-glucose deprivation (OGD) induced neuronal necroptosis and its underlying mechanism. To establish an in vitro model of neuronal necrosis, we used OGD/caspase-8 inhibitors (Q-VD-OPh, QVD) to treat rat primary cortical neurons (PCNs) after reoxygenation, wherein we found that the model cause an elevated ROS levels by mediating TXNIP/NLRP3 interactions, which in turn activated the NLRP3 inflammasome. Also, we observed that regulation of nuclear factor erythroid-2 related factor-2 (Nrf2) promoted heme oxygenase-1 (HO-1) expression and decreased TXNIP (a protein that relate oxidative stress to activation of inflammasome) and ROS levels, which negatively regulated the expression of OGD-induced activation of NLRP3 inflammasomes. In addition, HO-1 weakened NLRP3 inflammation body activation, which suggests that Nrf2-regulated HO-1 could block the interaction between TXNIP and NLRP3 in OGD/R-treated cortical neurons by inhibiting ROS production. Our study has discovered the importance of Nrf2/HO-1 signaling cascade for inhibiting inflammasome of NLRP3, which negatively regulated necrosis. Therefore, NLRP3 is considered a potential target for a novel neuroprotective approach, which can expand the therapeutic windows of stroke drugs.

The Role of Progranulin (PGRN) in the Pathogenesis of Ischemic Stroke

Stroke is a life-threatening medical condition and is a leading cause of disability. Cerebral ischemia is characterized by a distinct inflammatory response starting with the production of various cytokines and other inflammation-related agents. Progranulin (PGRN), a multifunctional protein, is critical in diverse physiological reactions, such as cell proliferation, inflammation, wound healing, and nervous system development. A mature PGRN is anti-inflammatory, while granulin, its derivative, conversely induces pro-inflammatory cytokine expression. PGRN is significantly involved in the brain tissue and its damage, for example, improving mood and cognitive disorders caused by cerebral ischemia. It may also have protective effects against nerve and spinal cord injuries by inhibiting neuroinflammatory response and apoptosis or it may be related to the proliferation, accumulation, differentiation, and activation of microglia. PGRN is a neurotrophic factor in the central nervous system. It may increase post-stroke neurogenesis of the subventricular zone (SVZ), which is particularly important in improving long-term brain function following cerebral ischemia. The neurogenesis enhanced via PGRN in the ischemic brain SVZ may be attributed to the induction of PI3K/AKT and MAPK/ERK signaling routes. PGRN can also promote the proliferation of neural stem/progenitor cells through PI3K/AKT signaling pathway. PGRN increases hippocampal neurogenesis, reducing anxiety and impaired spatial learning post-cerebral ischemia. PGRN alleviates cerebral ischemia/reperfusion injury by reducing endoplasmic reticulum stress and suppressing the NF-κB signaling pathway. PGRN can be introduced as a potent neuroprotective agent capable of improving post-ischemia neuronal actions, mainly by reducing and elevating the inflammatory and anti-inflammatory cytokines. Expression, storage, cleavage, and function of progranulin (PGRN) in the pathogenesis of ischemic stroke.

Progranulin released from microglial lysosomes reduces neuronal ferroptosis after cerebral ischemia in mice

The cellular redox state is essential for inhibiting ferroptosis. Progranulin (PGRN) plays an important role in maintaining the cellular redox state after ischemic brain injury. However, the effect of PGRN on ferroptosis and its underlying mechanism after cerebral ischemia remains unclear. This study assesses whether PGRN affects ferroptosis and explores its mechanism of action on ferroptosis after cerebral ischemia. We found endogenous PGRN expression in microglia increased on day 3 after ischemia. In addition, PGRN agonists chloroquine and trehalose upregulated PGRN expression, reduced brain infarct volume, and improved neurobehavioral outcomes after cerebral ischemia compared to controls (p < 0.05). Moreover, PGRN upregulation attenuated ferroptosis by decreasing malondialdehyde and increasing Gpx4, Nrf2, and Slc7a11 expression and glutathione content (p < 0.05). Furthermore, chloroquine induced microglial lysosome PGRN release, which was associated with increased neuron survival. Our results indicate that PGRN derived from microglial lysosomes effectively inhibits ferroptosis during ischemic brain injury, identifying it as a promising target for ischemic stroke therapy.

Icariin protects cerebral neural cells from ischemia‑reperfusion injury in an in vitro model by lowering ROS production and intracellular calcium concentration

Ischemia is one of the major causes of stroke. The present study investigated the protection of cultured neural cells by icariin (ICA) against ischemia-reperfusion (I/R) injury and possible mechanisms underlying the protection. Neural cells were isolated from neonatal rats and cultured in vitro. The cells were subjected to oxygen-glucose deprivation and reoxygenation (OGD-R) as an I/R mimic to generate I/R injury, and were post-OGD-R treated with ICA. Following the treatments, cell viability, apoptosis, reactive oxygen species (ROS), lactate dehydrogenase (LDH), superoxide dismutase (SOD) and Ca²⁺ concentration were assessed using Cell Counting Kit-8 assay, flow cytometry, CyQUANT™ LDH Cytotoxicity Assay, H₂DCFDA and SOD colorimetric activity kit. After OGD-R, considerable I/R injury was observed in the neural cells, as indicated by reduced cell viability, increased apoptosis and increased production of ROS and LDH (P<0.05). Cellular Ca²⁺ concentration was also increased, while SOD activity remained unchanged. Post-OGD-R ICA treatments increased cell viability up to 87.1% (P<0.05) and reduced apoptosis as low as 6.6% (P<0.05) in a concentration-dependent manner. The treatments also resulted in fewer ROS (P<0.05), lower extracellular LDH content (440.5 vs. 230.3 U/l; P<0.05) and reduced Ca²⁺ increase (P<0.05). These data suggest that ICA protects the neural cells from I/R injury in an in vitro model through antioxidation activity and maintaining cellular Ca²⁺ homeostasis. This function may be explored as a potential therapeutic strategy for ischemia-related diseases after further in vivo studies.

Ferrostatin-1 alleviates cerebral ischemia/reperfusion injury through activation of the AKT/GSK3β signaling pathway

Ischemic stroke is the major cause of disability and death worldwide, but post-stroke neuronal death and related mechanisms remain unclear. Ferroptosis, a newly identified type of regulated cell death, has been shown to be associated with neurological disorders, yet the exact relationship between ferroptosis and ischemic stroke has not been elucidated. The purpose of this study is to investigate the effects of ferroptosis-specific inhibitor ferrostatin-1 (Fer-1) on neuronal injury after cerebral ischemia/reperfusion (I/R) and the underlying mechanism. In this study, we demonstrated that ferroptosis does occur in the stroke model. We found that Fer-1 reduced the levels of iron and malondialdehyde, and increased the content of glutathione and the expression of solute carrier family 7 member 11 and glutathione peroxidase 4 in cerebral I/R models. Additionally, Fer-1 significantly reduced the infarct volume and improved neurobehavioral outcomes. Moreover, we found that Fer-1 increased the levels of phosphorylated AKT and GSK3β following cerebral I/R. To further investigate the functional role of the AKT in the neuroprotective effects of Fer-1, MCAO models and oxygen-glucose deprivation-induced HT22 cells were pretreated with the AKT inhibitor MK-2206 before treatment with Fer-1 and the protective effects of Fer-1 were reversed. In conclusion, Fer-1 has protective effects on cerebral I/R injury by activating the AKT/GSK3β pathway, indicating that ferroptosis may become a novel target in the treatment of ischemic stroke.

Deletion of Bak1 alleviates microglial necroptosis and neuroinflammation after experimental subarachnoid hemorrhage

Microglial necroptosis exacerbates neurodegenerative diseases, central nervous system (CNS) injury, and demonstrates a proinflammatory process, but its contribution to subarachnoid hemorrhage (SAH) is poorly characterized. BCL-2 homologous antagonist-killer protein (Bak1), a critical regulatory molecule of endogenous apoptosis, can be involved in the pathologic process of necroptosis by regulating mitochondrial permeability. In this study, we revealed microglia undergo necroptosis after SAH in vivo and vitro. Western blot revealed that Bak1 was elevated at 24 h after SAH. Knocked down of Bak1 by adeno-associated virus attenuates microglial necroptosis, alleviates neuroinflammation, and improves neurologic function after SAH in mice. Furthermore, oxyhemoglobin (10 μM) induced necroptosis in BV2 microglia, increasing Bak1 expression and mediating proinflammatory phenotype transformation, exacerbating oxidative stress and neuroinflammation. Abrogating BV2 Bak1 could reduce necroptosis by down-regulating the expression of phosphorylated pseudokinase mixed lineage kinase domain-like protein (p-MLKL), then down-regulating proinflammatory phenotype gene expression. RNA-Seq showed that disrupting BV2 Bak1 down-regulates multiple immune and inflammatory pathways and ameliorates cell injury by elevating thrombospondin 1 (THBS1) expression. In summary, we identified a critical regulatory role for Bak1 in microglial necroptosis and neuroinflammation after SAH. Bak1 is expected to be a potential target for the treatment strategy of SAH.

Functional mechanism of EGR3 in cerebral ischemia/reperfusion injury in rats by modulating transcription of pri-miR-146a/146b to miR-146 and suppressing SORT1 expression

OBJECTIVE

EGR3 is implicated in angiogenesis in rats with cerebral ischemia/reperfusion injury (CIRI). This research aimed to explore the effect and in vivo and ex vivo mechanisms of EGR3 in CIRI.

METHODS

CIRI rat models were established via middle cerebral artery occlusion. Cell models were established via oxygen-glucose deprivation/reoxygenation (OGD/R). Brain injury was assessed by neurological scoring, HE, and TTC staining. Inflammatory factors and oxidative stress markers were measured using corresponding kits. Mitochondrial membrane potential and mitochondrial respiration were examined by flow cytometry and respirometry. EGR3-miR-146 network was predicted on TransmiR v2.0 database. Target genes of miR-146 were screened on Starbase, Targetscan, and miRDB databases. miR-146 expression was determined by RT-qPCR. Levels of EGR3 and SORT1 were determined by Western blot. Binding relationships among EGR3, miR-146, and SORT1 were validated by dual-luciferase assay. EGR3, miR-146, and SORT1 levels were altered by injection or cell transfection to observe their functions.

RESULTS

EGR3 was poorly-expressed in CIRI rats and OGD/R-induced neurons. EGR3 overexpression reduced inflammatory factor levels and attenuated oxidative stress and mitochondrial injury in CIRI rats and OGD/R-induced neurons. EGR3 bound to miR-146b promoter region. EGR3 promoted pri-miR-146a/146b processing and stimulated miR-146 transcription. miR-146 overexpression ameliorated oxidative stress and mitochondrial injury and miR-146 downregulation abolished the effect of EGR3 overexpression in vitro. miR-146 targeted SORT1. SORT1 overexpression invalidated the protective function of miR-146 overexpression on oxidative stress and mitochondrial injury in vitro.

CONCLUSION

EGR3 protected against CIRI by mitigating oxidative stress and mitochondrial injury via the miR-146/SORT1 axis.

Adverse effects of SYP-3343 on zebrafish development via ROS-mediated mitochondrial dysfunction

As a newly-invented and highly-efficiency strobilurin fungicide, pyraoxystrobin (SYP-3343) has been recognized as a highly poisonous toxin for a variety of aquatic organisms. Nevertheless, the developmental toxicity and potential mechanism of SYP-3343 have not been well-documented. The results showed that SYP-3343 was relatively stable and maintained within the range of 20 % in 24 h, and the LC₅₀ value to embryos at 72 hpf was 17.13 μg/L. The zebrafish embryotoxicity induced by 1, 2, 4, and 8 μg/L SYP-3343 is demonstrated by repressive embryo incubation, enhancive mortality rate, abnormal heart rate, malformed morphological characteristic, and impaired spontaneous coiling, indicating SYP-3343 mostly exerted its toxicity in a dose- and time-dependent manner. Besides SYP-3343 was critically involved in regulating cell cycle, mitochondrial membrane potential, and reactive oxygen species production as well as zebrafish primary cells apoptosis, which can be mitigated using antioxidant N-acetyl-L-cysteine. A significant change occurred in total protein content, the biochemical indices, and antioxidant capacities owing to SYP-3343 exposure. Additionally, SYP-3343 altered the mRNA levels of heart development-, mitochondrial function-, and apoptosis-related genes in zebrafish embryos. These results indicated that SYP-3343 induced apoptosis accompanying reactive oxygen species-initiated mitochondrial dysfunction in zebrafish embryos.

Cell Death Mechanisms in Cerebral Ischemia-Reperfusion Injury

Ischemic stroke is one of the major causes of morbidity and mortality, affecting millions of people worldwide. Inevitably, the interruption of cerebral blood supply after ischemia may promote a cascade of pathophysiological processes. Moreover, the subsequent restoration of blood flow and reoxygenation may further aggravate brain tissue injury. Although recombinant tissue plasminogen activator (rt-PA) is the only approved therapy for restoring blood perfusion, the reperfusion injury and the narrow therapeutic time window restrict its application for most stroke patients. Increasing evidence indicates that multiple cell death mechanisms are relevant to cerebral ischemia-reperfusion injury, including apoptosis, necrosis, necroptosis, autophagy, pyroptosis, ferroptosis, and so on. Therefore, it is crucial to comprehend various cell death mechanisms and their interactions. In this review, we summarize the various signaling pathways underlying cerebral ischemia-reperfusion injury and elaborate on the crosstalk between the different mechanisms.

Do pyroptosis, apoptosis, and necroptosis (PANoptosis) exist in cerebral ischemia? Evidence from cell and rodent studies

Some scholars have recently developed the concept of PANoptosis in the study of infectious diseases where pyroptosis, apoptosis and necroptosis act in consort in a multimeric protein complex, PANoptosome. This allows all the components of PANoptosis to be regulated simultaneously. PANoptosis provides a new way to study the regulation of cell death, in that different types of cell death may be regulated at the same time. To test whether PANoptosis exists in diseases other than infectious diseases, we chose cerebral ischemia/reperfusion injury as the research model, collected articles researching cerebral ischemia/reperfusion from three major databases, obtained the original research data from these articles by bibliometrics, data mining and other methods, then integrated and analyzed these data. We selected papers that investigated at least two of the components of PANoptosis to check its occurrence in ischemia/reperfusion. In the cell model simulating ischemic brain injury, pyroptosis, apoptosis and necroptosis occur together and this phenomenon exists widely in different passage cell lines or primary neurons. Pyroptosis, apoptosis and necroptosis also occurred in rat and mouse models of ischemia/reperfusion injury. This confirms that PANoptosis is observed in ischemic brain injury and indicates that PANoptosis can be a target in the regulation of various central nervous system diseases.

Administration of an Acidic Sphingomyelinase (ASMase) Inhibitor, Imipramine, Reduces Hypoglycemia-Induced Hippocampal Neuronal Death

Severe hypoglycemia (below 35 mg/dL) appears most often in diabetes patients who continuously inject insulin. To rapidly cease the hypoglycemic state in this study, glucose reperfusion was conducted, which can induce a secondary neuronal death cascade following hypoglycemia. Acid sphingomyelinase (ASMase) hydrolyzes sphingomyelin into ceramide and phosphorylcholine. ASMase activity can be influenced by cations, pH, redox, lipids, and other proteins in the cells, and there are many changes in these factors in hypoglycemia. Thus, we expect that ASMase is activated excessively after hypoglycemia. Ceramide is known to cause free radical production, excessive inflammation, calcium dysregulation, and lysosomal injury, resulting in apoptosis and the necrosis of neurons. Imipramine is mainly used in the treatment of depression and certain anxiety disorders, and it is particularly known as an ASMase inhibitor. We hypothesized that imipramine could decrease hippocampal neuronal death by reducing ceramide via the inhibition of ASMase after hypoglycemia. In the present study, we confirmed that the administration of imipramine significantly reduced hypoglycemia-induced neuronal death and improved cognitive function. Therefore, we suggest that imipramine may be a promising therapeutic tool for preventing hypoglycemia-induced neuronal death.

Progranulin promotes hippocampal neurogenesis and alleviates anxiety-like behavior and cognitive impairment in adult mice subjected to cerebral ischemia

Aims

Cerebral ischemia can lead to anxiety and cognitive impairment due to the loss of hippocampal neurons. Facilitation of endogenous neurogenesis in the hippocampus is a potential therapeutic strategy for alleviating ischemia‐induced anxiety and cognitive impairment. Progranulin (PGRN), a secretory glycoprotein, has been reported to have a mitogentic effect on many cell types. However, it is not clear whether PGRN enhances hippocampal neurogenesis and promotes functional recovery.

Methods

Adult male C57BL/6 mice were subjected to permanent middle cerebral artery occlusion (pMCAO) and injected intracerebroventricularly with recombinant mouse PGRN 30 min after pMCAO. Anxiety‐like behavior was detected by the open field and the elevated plus maze tests, and spatial learning and memory abilities were evaluated by Morris water maze. Neurogenesis was examined by double labeling of BrdU and neural stem cells or neurons markers. For mechanism studies, the level of ERK1/2 and AKT phosphorylation were assessed by western blotting.

Results

Progranulin significantly alleviated anxiety‐like behavior and spatial learning and memory impairment induced by cerebral ischemia in mice. Consistent with the functional recovery, PGRN promoted neural stem cells (NSCs) proliferation and neuronal differentiation in the dentate gyrus (DG) after cerebral ischemia. PGRN upregulated the expression of phosphorylated ERK1/2 and Akt in the DG after cerebral ischemia.

Conclusions

Progranulin alleviates ischemia‐induced anxiety‐like behavior and spatial learning and memory impairment in mice, probably via stimulation of hippocampal neurogenesis mediated by activation of MAPK/ERK and PI3K/Akt pathways. PGRN might be a promising candidate for coping with ischemic stroke‐induced mood and cognitive impairment in clinic.

Proteomics-Based Approach to Identify Novel Blood Biomarker Candidates for Differentiating Intracerebral Hemorrhage From Ischemic Stroke-A Pilot Study

Background: A reliable distinction between ischemic stroke (IS) and intracerebral hemorrhage (ICH) is required for diagnosis-specific treatment and effective secondary prevention in patients with stroke. However, in resource-limited settings brain imaging, which is the current diagnostic gold standard for this purpose, is not always available in time. Hence, an easily accessible and broadly applicable blood biomarker-based diagnostic test differing stroke subtypes would be desirable. Using an explorative proteomics approach, this pilot study aimed to identify novel blood biomarker candidates for distinguishing IS from ICH.

Material and Methods: Plasma samples from patients with IS and ICH were drawn during hospitalization and were analyzed by using liquid chromatography/mass spectrometry. Proteins were identified using the human reference proteome database UniProtKB, and label-free quantification (LFQ) data were further analyzed using bioinformatic tools.

Results: Plasma specimens of three patients with IS and four patients with ICH with a median National Institute of Health Stroke Scale (NIHSS) of 12 [interquartile range (IQR) 10.5–18.5] as well as serum samples from two healthy volunteers were analyzed. Among 495 identified protein groups, a total of 368 protein groups exhibited enough data points to be entered into quantitative analysis. Of the remaining 22 top-listed proteins, a significant difference between IS and ICH was found for Carboxypeptidase N subunit 2 (CPN2), Coagulation factor XII (FXII), Plasminogen, Mannan-binding lectin serine protease 1, Serum amyloid P-component, Paraoxonase 1, Carbonic anhydrase 1, Fibulin-1, and Granulins.

Discussion: In this exploratory proteomics-based pilot study, nine candidate biomarkers for differentiation of IS and ICH were identified. The proteins belong to the immune system, the coagulation cascade, and the apoptosis system, respectively. Further investigations in larger cohorts of patients with stroke using additional biochemical analysis methods, such as ELISA or Western Blotting are now necessary to validate these markers, and to characterize diagnostic accuracy with regard to the development of a point-of-care-system for use in resource-limited areas.

Pomelo peel oil suppresses TNF-α-induced necroptosis and cerebral ischaemia-reperfusion injury in a rat model of cardiac arrest

CONTEXT

Pomelo peel oil (PPO) [Citrus maxima (Burm.) Merr. (Rutaceae)] is reported to possess antioxidant and antimelanogenic activities.

OBJECTIVE

To investigate the effect of PPO [Citrus maxima (Burm.) Merr. cv. Shatian Yu] on tumour necrosis factor-α (TNF-α)-induced necroptosis in cerebral ischaemia-reperfusion injury (CIRI) after cardiac arrest (CA).

MATERIALS AND METHODS

Male Sprague Dawley rats were randomly assigned to six groups: sham group, PP0-L (10 mg/kg), PPO-M (20 mg/kg), PPO-H (40 mg/kg) and two control groups (CA, 0.9% saline; Gly, 10% glycerol). All drugs were administered intravenously to the CA/CPR rats within 10 min after return of spontaneous circulation (ROSC). After 24 h, rats were assessed for neuronal injury via the neurological deficit score (NDS), cerebral cortex staining and transmission electron microscopy (TEM) and expression levels of TNF-α and necroptosis-related proteins by immunoreactivity staining and western blotting.

RESULTS

Compared to those in the sham group (survival rate, 100% and NDS, 80), the survival rate and NDS were significantly reduced in the model groups (CA, 56.25%, 70; Gly, 62.5%, 71; PPO-L, 75%, 72; PPO-M, 87.5%, 75; PPO-H, 81.25%, 74). In the PPO-M group, Nissl bodies were significantly increased (43.67 ± 1.906 vs. 17 ± 1.732), the incidence of pathomorphological injury was lower and the necroptosis markers (TNF-α, RIPK1, RIPK3, p-MLKL/MLKL) expression was downregulated compared to those in the CA group (p < 0.05).

DISCUSSION AND CONCLUSIONS

The neuroprotective effects of PPO in the CA rats suggested that PPO possibility as a health product enhances the resistance ability against brain injury for humans.

CaMK II Inhibition Attenuates ROS Dependent Necroptosis in Acinar Cells and Protects against Acute Pancreatitis in Mice

As a calcium-regulated protein, CaMK II is closely related to cell death, and it participates in the development of pathological processes such as reperfusion injury, myocardial infarction, and oligodendrocyte death. The function of CaMK II activation in acute pancreatitis (AP) remains unclear. In our study, we confirmed that the expression of p-CaMK II was increased significantly and consistently in injured pancreatic tissues after caerulein-induced AP. Then, we found that KN93, an inhibitor of CaMK II, could mitigate the histopathological manifestations in pancreatic tissues, reduce serum levels of enzymology, and decrease oxidative stress products. Accordingly, we elucidated the effect of KN93 in vitro and found that KN93 had a protective effect on the pancreatic acinar cell necroptosis pathway by inhibiting the production of ROS and decreasing the expression of RIP3 and p-MLKL. In addition, we identified the protective effect of KN93 on AP through another mouse model induced by pancreatic duct ligation (PDL). Together, these data demonstrated that CaMK II participates in the development of AP and that inhibiting CaMK II activation could protect against AP by reducing acinar cell necroptosis, which may provide a new idea target for the prevention and treatment of AP in the clinic.

Preclinical Evidence for the Interplay between Oxidative Stress and RIP1-Dependent Cell Death in Neurodegeneration: State of the Art and Possible Therapeutic Implications

Neurodegenerative diseases are the most frequent chronic, age-associated neurological pathologies having a major impact on the patient’s quality of life. Despite a heavy medical, social and economic burden they pose, no causative treatment is available for these diseases. Among the important pathogenic factors contributing to neuronal loss during neurodegeneration is elevated oxidative stress resulting from a disturbed balance between endogenous prooxidant and antioxidant systems. For many years, it was thought that increased oxidative stress was a cause of neuronal cell death executed via an apoptotic mechanism. However, in recent years it has been postulated that rather programmed necrosis (necroptosis) is the key form of neuronal death in the course of neurodegenerative diseases. Such assumption was supported by biochemical and morphological features of the dying cells as well as by the fact that various necroptosis inhibitors were neuroprotective in cellular and animal models of neurodegenerative diseases. In this review, we discuss the relationship between oxidative stress and RIP1-dependent necroptosis and apoptosis in the context of the pathomechanism of neurodegenerative disorders. Based on the published data mainly from cellular models of neurodegeneration linking oxidative stress and necroptosis, we postulate that administration of multipotential neuroprotectants with antioxidant and antinecroptotic properties may constitute an efficient pharmacotherapeutic strategy for the treatment of neurodegenerative diseases.

Effect of the combination of astragaloside IV and Panax notoginseng saponins on pyroptosis and necroptosis in rat models of cerebral ischemia-reperfusion

Pyroptosis and necroptosis are closely associated with the mechanism underlying cerebral ischemia-reperfusion (I/R) injury. The combination of astragaloside IV (AST IV) and Panax notoginseng saponins (PNS) has remarkable effects on the alleviation of cerebral I/R damage. However, whether inhibition of pyroptosis and necroptosis is the mechanism underlying the beneficial effects of this drug combination on cerebral I/R injury remains unclear. To explore the effects and mechanisms of drug treatment, middle cerebral artery occlusion was performed to induce I/R injury in rats, which was verified based on neurological deficit score (NDS), infarct volume and H&E staining. Activation of pyroptosis and necroptosis was detected by western blot analysis of associated proteins. The results of the present study demonstrated that treatment with AST IV and PNS, either alone or in combination, significantly reduced the NDS, cerebral infarct volume and cell injury rate in the cerebral cortex of rats. The treatments also improved pathological injury to the cerebral cortex and reduced the levels of proteins associated with pyroptosis and necroptosis. These effects were stronger in the combination drug group compared with groups treated with a single drug alone. The findings of the present study suggested that the combination of AST IV and PNS exhibited stronger neuroprotective effects in I/R injury than either drug alone, and that the underlying mechanism was associated with inhibition of pyroptosis and necroptosis.

Progranulin Protects Against Airway Remodeling Through the Modulation of Autophagy via HMGB1 Suppression in House Dust Mite-Induced Chronic Asthma

Purpose

Airway remodeling is an important feature of chronic asthma, and yet there are few effective therapeutic strategies. Progranulin (PGRN) has been shown to have lung protective functions, but the role of PGRN in asthmatic airway remodeling is unclear. We aim to explore the protective potential of PGRN on house dust mite (HDM)-induced airway remodeling and the underlying mechanisms.

Methods

In this study, a murine model of chronic asthma was established by HDM sensitization and challenge. Recombinant PGRN was intranasally administrated to mice during the phase of HDM challenge. TGF-β1-treated human airway epithelial BEAS-2B cells were utilized to explore the effect of PGRN on airway epithelia exposed to profibrotic conditions and molecular mechanisms.

Results

We found that PGRN treatment attenuated HDM-induced airway remodeling, as evidenced by the suppression of collagen accumulation, mucus overproduction and airway smooth muscle synthesis in HDM-challenged asthmatic mice lungs. Meanwhile, PGRN also reversed the increased levels of autophagy markers and autophagosomes in airway epithelia under mimic asthmatic conditions, thereby controlling the fibrotic process in vivo and in vitro. Specifically, overexpressed HMGB1 and the subsequent RAGE/MAPKs signaling activation due to HDM exposure were abrogated in PGRN-treated asthmatic mice. Furthermore, knockdown of HMGB1 expression significantly restrained the fibrosis formation in TGF-β1-induced airway epithelia accompanied by the downregulation of autophagic activity. However, enhancement of extracellular HMGB1 levels blunted the inhibition of autophagic flux by PGRN in airway epithelia, thereby resulting in the augmentation of collagen synthesis and fibrosis.

Conclusion

Taken together, our data revealed that PGRN protected against asthmatic airway remodeling by negatively regulating autophagy via HMGB1 suppression, which might provide new insights into the therapeutic options for HDM-induced chronic asthma.

Insight into Crosstalk between Ferroptosis and Necroptosis: Novel Therapeutics in Ischemic Stroke

Ferroptosis is a nonapoptotic form of cell death characterized by iron-dependent accumulation of lipid hydroperoxides to lethal levels. Necroptosis, an alternative form of programmed necrosis, is regulated by receptor-interacting protein (RIP) 1 activation and by RIP3 and mixed-lineage kinase domain-like (MLKL) phosphorylation. Ferroptosis and necroptosis both play important roles in the pathological progress in ischemic stroke, which is a complex brain disease regulated by several cell death pathways. In the past few years, increasing evidence has suggested that the crosstalk occurs between necroptosis and ferroptosis in ischemic stroke. However, the potential links between ferroptosis and necroptosis in ischemic stroke have not been elucidated yet. Hence, in this review, we overview and analyze the mechanism underlying the crosstalk between necroptosis and ferroptosis in ischemic stroke. And we find that iron overload, one mechanism of ferroptosis, leads to mitochondrial permeability transition pore (MPTP) opening, which aggravates RIP1 phosphorylation and contributes to necroptosis. In addition, heat shock protein 90 (HSP90) induces necroptosis and ferroptosis by promoting RIP1 phosphorylation and suppressing glutathione peroxidase 4 (GPX4) activation. In this work, we try to deliver a new perspective in the exploration of novel therapeutic targets for the treatment of ischemic stroke.

Resolving the graft ischemia-reperfusion injury during liver transplantation at the single cell resolution

Ischemia–reperfusion injury (IRI) remains the major reason for impaired donor graft function and increased mortality post-liver transplantation. The mechanism of IRI involves multiple pathophysiological processes and numerous types of cells. However, a systematic and comprehensive single-cell transcriptional profile of intrahepatic cells during liver transplantation is still unclear. We performed a single-cell transcriptome analysis of 14,313 cells from liver tissues collected from pre-procurement, at the end of preservation and 2 h post-reperfusion. We made detailed annotations of mononuclear phagocyte, endothelial cell, NK/T, B and plasma cell clusters, and we described the dynamic changes of the transcriptome of these clusters during IRI and the interaction between mononuclear phagocyte clusters and other cell clusters. In addition, we found that TNFAIP3 interacting protein 3 (TNIP3), specifically and highly expressed in Kupffer cell clusters post-reperfusion, may have a protective effect on IRI. In summary, our study provides the first dynamic transcriptome map of intrahepatic cell clusters during liver transplantation at single-cell resolution.

Changes in redox plasma proteome of Pon1-/- mice are exacerbated by a hyperhomocysteinemic diet

High-density lipoprotein (HDL), in addition to promoting reverse cholesterol transport, possesses anti-oxidative, anti-inflammatory, and antithrombotic activities, which are thought to be promoted by paraoxonase 1 (PON1), an HDL-associated enzyme. Reduced levels of PON1 are associated with increased oxidative stress and cardiovascular disease both in humans and Pon1^-/- mice. However, molecular basis of these associations are not fully understood. We used label-free mass spectrometry and Ingenuity Pathway Analysis bioinformatics resources to examine plasma proteomes in four-month-old Pon1^-/- mice (n = 32) and their Pon1^+/+ siblings (n = 15) fed with a hyper-homocysteinemic (HHcy) diet. We found that inactivation of the Pon1 gene resulted in dysregulation of proteins involved in the maintenance of redox homeostasis in mice. Redox-responsive proteins affected by Pon1^-/- genotype were more numerous in mice fed with HHcy diet (18 out of 89, 20%) than in mice fed with a control diet (4 out of 50, 8%). Most of the redox-related proteins affected by Pon1^-/- genotype in mice fed with a control diet (3 out of 4, 75%) were also affected in HHcy mice, while the majority of Pon1^-/- genotype-dependent redox proteins in HHcy mice (15 out of 18, 83%) were not affected by Pon1^-/- genotype in control diet animals. In addition to redox-related proteins, we identified proteins involved in acute phase response, complement/blood coagulation, lipoprotein/lipid metabolism, immune response, purine metabolism, glucose metabolism, and other proteins that were dysregulated by Pon1^-/- genotype in HHcy mice. Taken together, our findings suggest that Pon1 interacts with proteins involved in antioxidant defenses and other processes linked to cardiovascular disease. Dysregulation of these processes provides an explanation for the pro-oxidant and pro-atherogenic phenotypes observed in Pon1^-/- mice and humans with attenuated PON1 levels.

Single intracerebroventricular progranulin injection adversely affects the blood-brain barrier in experimental traumatic brain injury

Progranulin (PGRN) is a neurotrophic and anti-inflammatory factor with protective effects in animal models of ischemic stroke, subarachnoid hemorrhage, and traumatic brain injury (TBI). Administration of recombinant (r) PGRN prevents exaggerated brain pathology after TBI in Grn-deficient mice, suggesting that local injection of recombinant progranulin (rPGRN) provides therapeutic benefit in the acute phase of TBI. To test this hypothesis, we subjected adult male C57Bl/6N mice to the controlled cortical impact model of TBI, administered a single dose of rPGRN intracerebroventricularly (ICV) shortly before the injury, and examined behavioral and biological effects up to 5 days post injury (dpi). The anti-inflammatory bioactivity of rPGRN was confirmed by its capability to inhibit the inflammation-induced hypertrophy of murine primary microglia and astrocytes in vitro. In C57Bl/6N mice, however, ICV administration of rPGRN failed to attenuate behavioral deficits over the 5-day observation period. (Immuno)histological gene and protein expression analyses at 5 dpi did not reveal a therapeutic benefit in terms of brain injury size, brain inflammation, glia activation, cell numbers in neurogenic niches, and neuronal damage. Instead, we observed a failure of TBI-induced mRNA upregulation of the tight junction protein occludin and increased extravasation of serum immunoglobulin G into the brain parenchyma at 5 dpi. In conclusion, single ICV administration of rPGRN had not the expected protective effects in the acute phase of murine TBI, but appeared to cause an aggravation of blood-brain barrier disruption. The data raise questions about putative PGRN-boosting approaches in other types of brain injuries and disease.

Progranulin promotes functional recovery and neurogenesis in the subventricular zone of adult mice after cerebral ischemia

Progranulin (PGRN), a secreted glycosylated protein, has been reported to attenuate ischemia-induced cerebral injury through anti-inflammation, attenuation of blood-brain barrier disruption and neuroprotection. However, the effect of PGRN on neurogenesis in the subventricular zone (SVZ) after cerebral ischemia remains unclear. In this study, adult C57BL/6 mice were subjected to permanent middle cerebral artery occlusion (pMCAO), and different doses of recombinant mouse PGRN (r-PGRN, 0.3 ng, 1 ng, 5 ng) were intracerebroventricularly administered 30 min after pMCAO. Results showed that 1 ng r-PGRN markedly reduced infarct volume and rescued functional deficits 24 h after pMCAO. Meanwhile, 1 ng r-PGRN increased SVZ cell proliferation, as shown by a high number of bromodeoxyuridine-positive (BrdU+) cells and Ki-67+ cells in the ischemic ipsilateral SVZ 7 d after pMCAO. Additionally, PGRN increased the percentage of BrdU+/Doublecortin (DCX)+ cells in the ipsilateral SVZ 14 d after pMCAO and increased the percentage of new neurons (BrdU+/NeuN+ cells) in the peri-infarct striatum 28 d after pMCAO, suggesting that PGRN promotes neuronal differentiation. PGRN also upregulated phosphorylation of ERK1/2 and Akt in the ipsilateral SVZ 3 d after pMCAO. Our data indicate that PGRN treatment promotes acute functional recovery; most importantly, it also stimulates neurogenesis in the SVZ, which could be beneficial for long-term recovery after cerebral ischemia. The increase in neurogenesis could be associated with activation of the MAPK/ERK and PI3K/Akt pathways. These results suggest a potential new strategy utilizing PGRN in ischemic stroke therapy.

DAMPs and RAGE Pathophysiology at the Acute Phase of Brain Injury: An Overview

Early or primary injury due to brain aggression, such as mechanical trauma, hemorrhage or is-chemia, triggers the release of damage-associated molecular patterns (DAMPs) in the extracellular space. Some DAMPs, such as S100B, participate in the regulation of cell growth and survival but may also trigger cellular damage as their concentration increases in the extracellular space. When DAMPs bind to pattern-recognition receptors, such as the receptor of advanced glycation end-products (RAGE), they lead to non-infectious inflammation that will contribute to necrotic cell clearance but may also worsen brain injury. In this narrative review, we describe the role and ki-netics of DAMPs and RAGE at the acute phase of brain injury. We searched the MEDLINE database for “DAMPs” or “RAGE” or “S100B” and “traumatic brain injury” or “subarachnoid hemorrhage” or “stroke”. We selected original articles reporting data on acute brain injury pathophysiology, from which we describe DAMPs release and clearance upon acute brain injury, and the implication of RAGE in the development of brain injury. We will also discuss the clinical strategies that emerge from this overview in terms of biomarkers and therapeutic perspectives

S100a8 silencing attenuates inflammation, oxidative stress and apoptosis in BV2 cells induced by oxygen‑glucose deprivation and reoxygenation by upregulating GAB1 expression

S100a8 serves an important role in cell differentiation and is abnormally expressed in common tumors, but there are few studies on the association between S100a8 and brain I/R injury. The present study aimed to investigate the role of S100a8 in oxygen-glucose deprivation and reoxygenation (OGD/R)-induced BV2 microglia cell injury, and to elucidate the potential underlying molecular mechanisms. BV2 cells were exposed to OGD/R to mimic ischemia/reperfusion (I/R) injury in vitro. S100a8 expression was detected via reverse transcription-quantitative PCR and western blot analyses. Following transfection with short hairpin RNAs targeting S100a8, the levels of inflammatory cytokines and oxidative stress-related factors were determined using commercial kits. Apoptosis was assessed using flow cytometric analysis and the expression levels of apoptosis-related proteins were determined using western blot analysis. Subsequently, the mRNA and protein levels of Grb2-associated binder 1 (GAB1) were assessed following S100a8 silencing. Immunoprecipitation (IP) was performed to verify the association between S100a8 and GAB1. The levels of inflammation, oxidative stress and apoptosis were assessed following GAB1 silencing, along with S100a8 silencing in BV2 cells subjected to OGD/R. The results indicated that exposure to OGD/R markedly upregulated S100a8 expression in BV2 cells. S100a8 silencing inhibited inflammation, oxidative stress and apoptosis, accompanied by changes in the expression of related proteins. The IP assay revealed a strong interaction between GAB1 and S100a8. In addition, GAB1 silencing reversed the inhibitory effects of S100a8 silencing on inflammation, oxidative stress and apoptosis in OGD/R-stimulated BV2 cells. Taken together, the results of the present study demonstrated that S100a8 silencing alleviated inflammation, oxidative stress and the apoptosis of BV2 cells induced by OGD/R, partly by upregulating the expression of GAB1. Thus, these findings may potentially provide a novel direction to develop therapeutic strategies for cerebral I/R injury.

Procyanidins exhibits neuroprotective activities against cerebral ischemia reperfusion injury by inhibiting TLR4-NLRP3 inflammasome signal pathway

BACKGROUND

Ischemic stroke is a serious cardiovascular disease with high morbidity and mortality rates that affects millions of people worldwide.Currently, the only therapy with proven efficacy for acute ischemic stroke is alteplase, however, it still has many shortcomings and limitations. Therefore,we screen new compounds from traditional Chinese medicine to explore their efficacy against ischemic reperfusion injury. Procyanidins, a natural productextracted from grapes seed, which have been shown can ameliorate cerebral ischemic injury. However, the underlying mechanism is still not very clear. Theaim of this study was to investigate the effect of procyanidins on middle cerebral artery occlusion/reperfusion (MCAO/R)-mediated cerebral ischemic injuryand its underlying possible mechanisms.

METHODS

SD rats were used to evaluate the effect of procyanidins on MCAO/R induced cerebral ischemic injury in vivo. Histological analysis was used toassess neuronal apoptosis. Cell signaling was assayed by Western blot.

RESULTS

In this study, we found that procyanidins can significantly ameliorate the middle cerebral artery occlusion/reperfusion (MCAO/R)-mediatedneurological deficits, and relieved brain edema, cerebral infarction volume, histopathological damage and apoptosis in rats. In addition, procyanidins canalso markedly inhibit MCAO/R and oxygen-glucose deprivation/reoxygenation (OGD/R)-mediated activation of TLR4-p38-NF-κB-NLRP3 signalingpathway in vitro and in vivo. Moreover, procyanidins can inhibit MCAO/R and OGD/R-induced the production of inflammatory cytokines such asinterleukin-1β (IL-1β) in vitro and in vivo. Besides, treatment with TLR4 inhibitor (Cli-095) in BV2 cell also shows the same effect.

CONCLUSION

Altogether, these data suggested that procyanidins exerted a potential neuroprotective effect may by inhibit the TLR4-p38-NF-κB-NLRP3signaling pathway in the brain in MCAO/R rats.

Eupafolin alleviates cerebral ischemia/reperfusion injury in rats via blocking the TLR4/NF‑κB signaling pathway

Eupatorium perfoliatum L. (E. perfoliatium) has been used traditionally for treating fever, malaria and inflammation‑associated diseases. Eupafolin, the extract of E. perfoliatium, was also reported to suppress inflammation. The present study aimed to investigate the protective effects of eupafolin on cerebral ischemia/reperfusion (I/R) injury in rats and its possible underlying mechanisms. Cerebral I/R injury was induced in rats by middle cerebral artery occlusion (MCAO) for 1.5 h, followed by reperfusion. The rats were randomly assigned into six groups: Control, model, 10 mg/kg eupafolin, 20 mg/kg eupafolin, 50 mg/kg eupafolin and 20 mg/kg nimodipine. Eupafolin and nimodipine were intragastrically administrated to the rats 1 week before MCAO induction. Following reperfusion for 24 h, the neurological deficit was scored, and brain samples were harvested for evaluating encephaledema, infarct volume, oxidative stress, apoptosis, inflammation and the expression of TLR4/NF‑κB signaling. The results revealed that eupafolin decreased the neurological score, relieved encephaledema and decreased infarct volume. Eupafolin also attenuated oxidative stress, neuronal apoptosis and inflammation, with decreases in lactate dehydrogenase, malondialdehyde, TUNEL‑positive cells, Bax and caspase‑3, along with TNF‑α, IL‑1β and IL‑6, but increases in superoxide dismutase and Bcl‑2 levels. Furthermore, eupafolin may decrease the expression of TLR4 downstream proteins and proteins involved in the NF‑κB pathway. Treatment with TLR4 agonist‑LPS significantly blunted the protective effect of eupafolin on encephaledema and cerebral infarct. Meanwhile, 20 mg/kg eupafolin showed nearly equivalent effects to the positive‑control drug nimodipine. In conclusion, eupafolin protected against cerebral I/R injury in rats and the underlying mechanism may be associated with the suppression of apoptosis and inflammation via inhibiting the TLR4/ NF‑κB signaling pathway.

The possible roles of necroptosis during cerebral ischemia and ischemia / reperfusion injury

Cell death is a process consequential to cerebral ischemia and cerebral ischemia/reperfusion (I/R) injury. Recent evidence suggest that necroptosis has been involved in the pathogenesis of ischemic brain injury. The mechanism of necroptosis is initiated by an activation of inflammatory receptors including tumor necrosis factor, toll like receptor, and fas ligands. The signals activate the receptor-interacting protein kinase (RIPK) 1, 3, and a mixed-lineage kinase domain-like pseudokinase (MLKL) to instigate necroptosis. RIPK1 inhibitor, necrostatin-1, was developed, and dramatically reduced brain injury following cerebral ischemia in mice. Consequently, necroptosis could be a novel therapeutic target for stroke, which aims to reduce long-term adverse outcomes after cerebral ischemia. Several studies have been conducted to test the roles of necroptosis on cerebral ischemia and cerebral I/R injury, and the efficacy of necrostatin-1 has been tested in those models. Evidence regarding the roles of necroptosis and the effects of necrostatin-1, from in vitro and in vivo studies, has been summarized and discussed. In addition, other therapeutic managements, involving in necroptosis, are also included in this review. We believe that the insights from this review might clarify the clinical perspective and challenges involved in future stroke treatment by targeting the necroptosis pathway.