Low-density lipoprotein receptor (LDLR) regulates NLRP3-mediated neuronal pyroptosis following cerebral ischemia/reperfusion injury

Cholesterol metabolism: physiological versus pathological aspects in intracerebral hemorrhage

Cholesterol is an important component of plasma membranes and participates in many basic life functions, such as the maintenance of cell membrane stability, the synthesis of steroid hormones, and myelination. Cholesterol plays a key role in the establishment and maintenance of the central nervous system. The brain contains 20% of the whole body's cholesterol, 80% of which is located within myelin. A huge number of processes (e.g., the sterol regulatory element-binding protein pathway and liver X receptor pathway) participate in the regulation of cholesterol metabolism in the brain via mechanisms that include cholesterol biosynthesis, intracellular transport, and efflux. Certain brain injuries or diseases involving crosstalk among the processes above can affect normal cholesterol metabolism to induce detrimental consequences. Therefore, we hypothesized that cholesterol-related molecules and pathways can serve as therapeutic targets for central nervous system diseases. Intracerebral hemorrhage is the most severe hemorrhagic stroke subtype, with high mortality and morbidity. Historical cholesterol levels are associated with the risk of intracerebral hemorrhage. Moreover, secondary pathological changes after intracerebral hemorrhage are associated with cholesterol metabolism dysregulation, such as neuroinflammation, demyelination, and multiple types of programmed cell death. Intracellular cholesterol accumulation in the brain has been found after intracerebral hemorrhage. In this paper, we review normal cholesterol metabolism in the central nervous system, the mechanisms known to participate in the disturbance of cholesterol metabolism after intracerebral hemorrhage, and the links between cholesterol metabolism and cell death. We also review several possible and constructive therapeutic targets identified based on cholesterol metabolism to provide cholesterol-based perspectives and a reference for those interested in the treatment of intracerebral hemorrhage.

Overexpression of low-density lipoprotein receptor prevents neurotoxic polarization of astrocytes via inhibiting NLRP3 inflammasome activation in experimental ischemic stroke

JOURNAL/nrgr/04.03/01300535-202502000-00027/figure1/v/2024-05-28T214302Z/r/image-tiff Neurotoxic astrocytes are a promising therapeutic target for the attenuation of cerebral ischemia/reperfusion injury. Low-density lipoprotein receptor, a classic cholesterol regulatory receptor, has been found to inhibit NLR family pyrin domain containing protein 3 (NLRP3) inflammasome activation in neurons following ischemic stroke and to suppress the activation of microglia and astrocytes in individuals with Alzheimer's disease. However, little is known about the effects of low-density lipoprotein receptor on astrocytic activation in ischemic stroke. To address this issue in the present study, we examined the mechanisms by which low-density lipoprotein receptor regulates astrocytic polarization in ischemic stroke models. First, we examined low-density lipoprotein receptor expression in astrocytes via immunofluorescence staining and western blotting analysis. We observed significant downregulation of low-density lipoprotein receptor following middle cerebral artery occlusion reperfusion and oxygen-glucose deprivation/reoxygenation. Second, we induced the astrocyte-specific overexpression of low-density lipoprotein receptor using astrocyte-specific adeno-associated virus. Low-density lipoprotein receptor overexpression in astrocytes improved neurological outcomes in middle cerebral artery occlusion mice and reversed neurotoxic astrocytes to create a neuroprotective phenotype. Finally, we found that the overexpression of low-density lipoprotein receptor inhibited NLRP3 inflammasome activation in oxygen-glucose deprivation/reoxygenation injured astrocytes and that the addition of nigericin, an NLRP3 agonist, restored the neurotoxic astrocyte phenotype. These findings suggest that low-density lipoprotein receptor could inhibit the NLRP3-meidiated neurotoxic polarization of astrocytes and that increasing low-density lipoprotein receptor in astrocytes might represent a novel strategy for treating cerebral ischemic stroke.

E3 ubiquitin ligase MARCH1 reduces inflammation and pyroptosis in cerebral ischemia-reperfusion injury via PCSK9 downregulation

Pyroptosis has been regarded as caspase-1-mediated monocyte death that induces inflammation, showing a critical and detrimental role in the development of cerebral ischemia-reperfusion injury (IRI). MARCH1 is an E3 ubiquitin ligase that exerts potential anti-inflammatory functions. Therefore, the study probed into the significance of MARCH1 in inflammation and pyroptosis elicited by cerebral IRI. Middle cerebral artery occlusion/reperfusion (MCAO/R)-treated mice and oxygen glucose deprivation/reoxygenation (OGD/R)-treated hippocampal neurons were established to simulate cerebral IRI in vivo and in vitro. MARCH1 and PCSK9 expression was tested in MCAO/R-operated mice, and their interaction was identified by means of the cycloheximide assay and co-immunoprecipitation. The functional roles of MARCH1 and PCSK9 in cerebral IRI were subsequently determined by examining the neurological function, brain tissue changes, neuronal viability, inflammation, and pyroptosis through ectopic expression and knockdown experiments. PCSK9 expression was increased in the brain tissues of MCAO/R mice, while PCSK9 knockdown reduced brain damage and neurological deficits. Additionally, inflammation and pyroptosis were inhibited in OGD/R-exposed hippocampal neurons upon PCSK9 knockdown, accompanied by LDLR upregulation and NLRP3 inflammasome inactivation. Mechanistic experiments revealed that MARCH1 mediated ubiquitination and degradation of PCSK9, lowering PCSK9 protein expression. Furthermore, it was demonstrated that MARCH1 suppressed inflammation and pyroptosis after cerebral IRI by downregulating PCSK9 both in vivo and in vitro. Taken together, the present study demonstrate the protective effect of MARCH1 against cerebral IRI through PCSK9 downregulation, which might contribute to the discovery of new therapies for improving cerebral IRI.

Low-Density Lipoprotein Cholesterol to Triglyceride Ratio and Clinical Outcomes after Acute Ischaemic Stroke or Transient Ischaemic Attack

AIMS

Studies showed that low-density lipoprotein cholesterol (LDL-C) to triglyceride (TG) ratio could be used as a predictive parameter of low-density lipoprotein oxidation in vivo and the level of small dense LDL-C. However, whether LDL-C/TG ratio is associated with stroke prognosis remains unclear. We investigated the associations of LDL-C/TG ratio with outcomes in patients with acute ischaemic stroke (AIS) or transient ischaemic attacks (TIA) and explored whether it produced more predictive value than LDL-C and TG.

METHODS

Data were derived from the Third China National Stroke Registry (CNSR-III). Multivariable Cox regression for stroke recurrence, composite vascular events and all-cause death and logistic regression for the poor functional outcome (modified Rankin Scale score 3-6) were used.

RESULTS

A total of 14123 patients were included. After adjusting for confounding factors, quartile 4 of LDL-C/TG ratio was associated with an increased risk of recurrent stroke (hazard ratio [HR], 1.27; 95% confidence interval [CI], 1.03-1.56), composite vascular events (HR,1.23; 95% CI, 1.00-1.52), death (HR,1.70; 95% CI, 1.13-2.54) and poor functional outcome (odds ratio, 1.34; 95% CI, 1.12-1.61) at 3 months follow-up compared with quartile 1. We also found that quartile 4 of LDL-C and TG was positively and negatively associated with poor functional outcome at 3 months, respectively. LDL-C/TG ratio performed better than LDL-C or TG in predicting clinical outcomes.

CONCLUSIONS

LDL-C/TG ratio was associated with the risk of stroke recurrence, composite vascular events, death and poor functional outcome in patients with AIS or TIA.

Elabela ameliorates neuronal pyroptosis and mitochondrial fission via APJ/ZBP1 signaling in ischemic stroke

Pyroptosis signifies a significant form of programmed neuronal demise subsequent to ischemic stroke. In our prior investigations, we demonstrated that the Elabela (ELA)-Apelin receptor (APJ) axis alleviated neuronal death by improving collateral circulation and mitigating ferroptosis in a murine model of middle cerebral artery occlusion (MCAO). However, the connection between ELA and neuronal pyroptosis remains further elucidation. Here, we observed an upregulation of ELA and APJ expression in both murine brain specimens and cultured HT-22 hippocampal neurons exposed to experimental ischemic stroke. ELA administration markedly diminished the infarct size in comparison to controls. ELA treatment ameliorated neurological deficits and anxiety-like symptoms in mice with stroke, concurrently inhibiting pyroptosis and mitochondria fission in neurons. Conversely, ELA knockdown yielded the opposite effects. Utilizing RNA-sequencing analysis, we identified a candidate for pyroptosis priming, Z-DNA-binding protein 1 (ZBP1), which was suppressed in ELA-treated HT-22 neurons during oxygen-glucose deprivation/reperfusion (OGD/R). Subsequent co-immunoprecipitation analyses demonstrated the binding between APJ and ZBP1. Specifically, APJ suppressed ZBP1 to inhibit NLRP3 inflammasome activation and dynamin-related protein 1-mediated mitochondrial fission in neurons. In summary, our findings suggest that ELA functions as a stroke-induced signal limiting neuronal pyroptosis and mitochondrial fission via APJ/ZBP1 signaling, thereby underscoring ELA as a potential therapeutic target for ischemic stroke treatment.

Myelin debris phagocytosis in demyelinating disease

Demyelinating diseases are often caused by a variety of triggers, including immune responses, viral infections, malnutrition, hypoxia, or genetic factors, all of which result in the loss of myelin in the nervous system. The accumulation of myelin debris at the lesion site leads to neuroinflammation and inhibits remyelination; therefore, it is crucial to promptly remove the myelin debris. Initially, Fc and complement receptors on cellular surfaces were the primary clearance receptors responsible for removing myelin debris. However, subsequent studies have unveiled the involvement of additional receptors, including Mac-2, TAM receptors, and the low-density lipoprotein receptor-related protein 1, in facilitating the removal process. In addition to microglia and macrophages, which serve as the primary effector cells in the disease phase, a variety of other cell types such as astrocytes, Schwann cells, and vascular endothelial cells have been demonstrated to engage in the phagocytosis of myelin debris. Furthermore, we have concluded that oligodendrocyte precursor cells, as myelination precursor cells, also exhibit this phagocytic capability. Moreover, our research group has innovatively identified the low-density lipoprotein receptor as a potential phagocytic receptor for myelin debris. In this article, we discuss the functional processes of various phagocytes in demyelinating diseases. We also highlight the alterations in signaling pathways triggered by phagocytosis, and provide a comprehensive overview of the various phagocytic receptors involved. Such insights are invaluable for pinpointing potential therapeutic strategies for the treatment of demyelinating diseases by targeting phagocytosis.

Gasdermin D could be lost in the brain parenchyma infarct core and a pyroptosis-autophagy inhibition effect of Jie-Du-Huo-Xue decoction after stroke

Background

The Chinese ethnic medicine Jie-Du-Huo-Xue Decoction (JDHXD) is used to alleviate neuroinflammation in cerebral ischemia (CI). Our previous studies have confirmed that JDHXD can inhibit microglial pyroptosis in CI. However, the pharmacological mechanism of JDHXD in alleviating neuroinflammation and pyroptosis needs to be further elucidated. New research points out that there is an interaction between autophagy and inflammasome NLRP3, and autophagy can help clear NLRP3. The NLRP3 is a key initiator of pyroptosis and autophagy. The effect of JDHXD promoting autophagy to clear NLRP3 to inhibit pyroptosis on cerebral ischemia-reperfusion inflammatory injury is currently unknown. We speculate that JDHXD can inhibit pyroptosis in CI by promoting autophagy to clear NLRP3.

Methods

Chemical characterization of JDHXD was performed using LC-MS. Model of middle cerebral artery occlusion/reperfusion (MCAO/R) was established in SD rats. Neurological deficits, neuron damage, and cerebral infarct volume were evaluated. Western Blot and immunofluorescence were used to detect neuronal pyroptosis and autophagy.

Results

30 possible substance metabolites in JDHXD medicated serum were analyzed by LC-MS (Composite Score > 0.98). Furthermore, JDHXD protects rat neurological function and cerebral infarct size after CI. JDHXD inhibited the expression of pyroptosis and autophagy after CI. Our western blot and immunofluorescence results showed that JDHXD treatment can reduce the expression of autophagy-related factors ULK1, beclin1, and LC3-Ⅱ. The expression of NLRP3 protein was lower in the JDHXD group than in the I/R group. Compared with the I/R group, the expressions of pyroptosis-related factors caspase-1 P 10, GSDMD-NT, IL-18, and IL-1β decreased in the JDHXD group. Furthermore, we observed an unexpected result: immunofluorescence demonstrated that Gasdermin D (GSDMD) was significantly absent in the infarct core, and highly expressed in the peri-infarct and contralateral cerebral hemispheres. This finding challenges the prevailing view that GSDMD is elevated in the ischemic cerebral hemisphere.

Conclusion

JDHXD inhibited pyroptosis and autophagy after MCAO/R. JDHXD suppressed pyroptosis and autophagy by inhibiting NLRP3, thereby alleviating CI. In addition, we present a different observation from previous studies that the expression of GSDMD in the infarct core was lower than that in the peri-infarct and contralateral non-ischemic hemispheres on day 3 of CI.

Activation of Inflammasomes and Relevant Modulators for the Treatment of Microglia-mediated Neuroinflammation in Ischemic Stroke

As the brain's resident immune patrol, microglia mediate endogenous immune responses to central nervous system injury in ischemic stroke, thereby eliciting either neuroprotective or neurotoxic effects. The association of microglia-mediated neuroinflammation with the progression of ischemic stroke is evident through diverse signaling pathways, notably involving inflammasomes. Within microglia, inflammasomes play a pivotal role in promoting the maturation of interleukin-1β (IL-1β) and interleukin-18 (IL-18), facilitating pyroptosis, and triggering immune infiltration, ultimately leading to neuronal cell dysfunction. Addressing the persistent and widespread inflammation holds promise as a breakthrough in enhancing the treatment of ischemic stroke.

PRDX1 Interfering Peptide Disrupts Amino Acids 70-90 of PRDX1 to Inhibit the TLR4/NF-κB Signaling Pathway and Attenuate Neuroinflammation and Ischemic Brain Injury

Ischemic stroke ranks among the leading causes of death and disability in humans and is accompanied by motor and cognitive impairment. However, the precise mechanisms underlying injury after stroke and effective treatment strategies require further investigation. Peroxiredoxin-1 (PRDX1) triggers an extensive inflammatory cascade that plays a pivotal role in the pathology of ischemic stroke, resulting in severe brain damage from activated microglia. In the present study, we used molecular dynamics simulation and nuclear magnetic resonance to detect the interaction between PRDX1 and a specific interfering peptide. We used behavioral, morphological, and molecular experimental methods to demonstrate the effect of PRDX1-peptide on cerebral ischemia-reperfusion (I/R) in mice and to investigate the related mechanism. We found that PRDX1-peptide bound specifically to PRDX1 and improved motor and cognitive functions in I/R mice. In addition, pretreatment with PRDX1-peptide reduced the infarct area and decreased the number of apoptotic cells in the penumbra. Furthermore, PRDX1-peptide inhibited microglial activation and downregulated proinflammatory cytokines including IL-1β, IL-6, and TNF-α through inhibition of the TLR4/NF-κB signaling pathway, thereby attenuating ischemic brain injury. Our findings clarify the precise mechanism underlying PRDX1-induced inflammation after ischemic stroke and suggest that the PRDX1-peptide can significantly alleviate the postischemic inflammatory response by interfering with PRDX1 amino acids 70-90 and thereby inhibiting the TLR4/NF-κB signaling pathway. Our study provides a theoretical basis for a new therapeutic strategy to treat ischemic stroke.

Function of miR-21-5p derived from ADSCs-exos on the neuroinflammation after cerebral ischemia

INTRODUCTION

Cerebral ischemia (CI) induces a profound neuroinflammatory response, but the underlying molecular mechanism remains unclear. Exosomes from adipose-derived stem cells (ADSC-exos) have been found to play a crucial role in cell communication by transferring molecules including microRNAs (miRNAs), which have been shown to modulate the inflammatory response after CI and are viable molecular targets for altering brain function. The current study aimed to explore the contribution of ADSC-exosomal miR-21-5p to the neuroinflammation after CI.

METHODS

The differentially expressed miR-21-5p in CI was screened based on literature search. The target mRNAs of miR-21-5p were predicted using online databases and verified by luciferase reporter assay. Then, BV2 cells were treated with hemin to simulate the inflammatory response after CI, and its animal model was induced using the MCAO method. Ischemia was evaluated in rats using 2, 3, 5-triphenyl tetrazolium chloride (TTC) staining. ADSCs-exos were further isolated and identified by western blot analysis and transmission electron microscope.

RESULTS

MiR-21-5p was significantly down-regulated in CI and alleviated neuropathic damage after CI by the PIK3R1/PI3K/AKT signaling axis. And miR-21-5p derived from ADSCs-exos alleviated neuroinflammation after CI via promoting microglial M2 polarization.

CONCLUSION

We demonstrated that ADSC-exosomal miR-21-5p mitigated post-CI inflammatory response through the PIK3R1/PI3K/AKT signaling axis and could offer neuroprotection after CI through promoting polarization of M2 microglia.

Crosstalk between metabolism and cell death in tumorigenesis

It is generally recognized that tumor cells proliferate more rapidly than normal cells. Due to such an abnormally rapid proliferation rate, cancer cells constantly encounter the limits of insufficient oxygen and nutrient supplies. To satisfy their growth needs and resist adverse environmental events, tumor cells modify the metabolic pathways to produce both extra energies and substances required for rapid growth. Realizing the metabolic characters special for tumor cells will be helpful for eliminating them during therapy. Cell death is a hot topic of long-term study and targeting cell death is one of the most effective ways to repress tumor growth. Many studies have successfully demonstrated that metabolism is inextricably linked to cell death of cancer cells. Here we summarize the recently identified metabolic characters that specifically impact on different types of cell deaths and discuss their roles in tumorigenesis.

Neuroprotective effects of galectin‑1 on cerebral ischemia/reperfusion injury by regulating oxidative stress

Oxidative stress contributes to the pathology of cerebral ischemia/reperfusion (I/R) injury. Galectin-1 has shown an anti-oxidative stress effect. The present study investigated whether this anti-oxidative stress effect can account for the neuroprotective actions of galectin-1 induced by cerebral I/R injury. A cerebral I/R injury model was created in C57Bl/6 mice by transient occlusion of the middle cerebral artery, after which the mice were treated with galectin-1 for 3 days. Infarct volumes were measured. A rotarod test and neurological deficit score assessment was performed to evaluate the neurological deficits. Oxidative stress was evaluated by measuring the levels of reactive oxygen species (ROS) and lipid peroxidation malondialdehyde (MDA), while the anti-oxidative stress status was assessed by measuring molecules such as catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidation enzyme (GSH-Px) in the ischemic cerebral hemisphere of mice. The inflammatory cytokines, including Interleukin 1 (IL-1), IL-6 and tumor necrosis factor alpha (TNF-α) were measured, and the expression of microglia was evaluated by immunohistochemistry in the ischemic cerebral hemisphere of mice. Galectin-1 treatment ameliorated neurological deficits and reduced infarct volumes in the mice model with cerebral I/R injury. Moreover, it was demonstrated that galectin-1 can significantly alleviate cerebral I/R injury in the ischemic cerebral hemisphere by decreasing the production of ROS and MDA, but increasing the production of CAT, SOD and GSH-Px. Galectin-1 treatment decreased microglia expression, and IL-1, IL-6 and TNF-α levels in the ischemic cerebral hemisphere of mice. Galectin-1 could improve the outcome of cerebral I/R injury by alleviating oxidative stress. Moreover, the neuroprotective effect of galectin-1 in cerebral ischemia could be related to its anti-oxidative stress effect.

STAT4-Mediated Klotho Up-Regulation Contributes to the Brain Ischemic Tolerance by Cerebral Ischemic Preconditioning via Inhibiting Neuronal Pyroptosis

Our previous study has proved that the Klotho up-regulation participated in cerebral ischemic preconditioning (CIP)-induced brain ischemic tolerance. However, the exact neuroprotective mechanism of Klotho in CIP remains unclear. We explored the hypothesis that STAT4-mediated Klotho up-regulation contributes to the CIP-induced brain ischemic tolerance via inhibiting neuronal pyroptosis. Firstly, the expressions of pyroptosis-associated proteins (i.e., NLRP3, GSDMD, pro-caspase-1, and cleaved caspase-1) in hippocampal CA1 region were determined during the process of brain ischemic tolerance. We found the expression of pyroptosis-associated proteins was significantly up-regulated in the ischemic insult (II) group, and showed no significant changes in the CIP group. The expression level of each pyroptosis-associated proteins was lower in the CIP + II group than that in the II group. Inhibition of Klotho expression increased the expression of pyroptosis-associated proteins in the CIP + II group and blocked the CIP-induced brain ischemic tolerance. Injection of Klotho protein decreased the expression of pyroptosis-associated proteins in the II group, and protected neurons from ischemic injury. Secondly, the transcription factor STAT4 of Klotho was identified by bioinformatic analysis. Double luciferase reporter gene assay and chromatin immunoprecipitation assay showed STAT4 can bind to the site between nt - 881 and - 868 on the Klotho promoter region and positively regulates Klotho expression. Moreover, we found CIP significantly enhanced the expression of STAT4. Knockdown STAT4 suppressed Klotho up-regulation after CIP and blocked the CIP-induced brain ischemic tolerance. Collectively, it can be concluded that STAT4-mediated the up-regulation of Klotho contributed to the brain ischemic tolerance induced by CIP via inhibiting pyroptosis.

Identification and characterization of extrachromosomal circular DNA in large-artery atherosclerotic stroke

Extrachromosomal circular DNA (eccDNA) is a new biomarker and regulator of diseases. However, the role of eccDNAs in large-artery atherosclerotic (LAA) stroke remains unclear. Through high-throughput circle-sequencing technique, the length distribution, genomic characteristic and motifs feature of plasma eccDNA from healthy controls (CON) and patients with LAA stroke were analysed. Then, the potential functions of the annotated eccDNAs were investigated using GO and KEGG pathway analyses. EccDNAs mapped to the reference genome showed SHN3 and BCL6 were LAA stroke unique transcription factors. The genes of differentially expressed eccDNAs between LAA stroke patients and CON were mainly involved in axon/dendrite/neuron projection development and maintenance of cellular structure via Wnt, Rap1 and MAPK pathways. Moreover, LAA stroke unique eccDNA genes played a role in regulation of coagulation and fibrinolysis, and there were five LAA stroke unique eccDNAs (Chr2:12724406-12724784, Chr4:1867120-186272046, Chr4:186271494-186271696, Chr7:116560296-116560685 and Chr11:57611780-5761192). Additionally, POLR2C and AURKA carried by ecDNAs (eccDNA size >100 kb) of LAA stroke patients were significantly associated with development of LAA stroke. Our data firstly revealed the characteristics of eccDNA in LAA stroke and the functions of LAA stroke unique eccDNAs and eccDNA genes, suggesting eccDNA is a novel biomarker and mechanism of LAA stroke.

Pyroptosis: The Determinator of Cell Death and Fate in Acute Kidney Injury

Background

Acute kidney injury (AKI) is kidney damage that leads to a rapid decline in function. AKI primarily occurs when the tubular epithelium is damaged, causing swelling, loss of brush margin, and eventual apoptosis. Research has shown that tubular epithelial cell damage in AKI is linked to cell cycle arrest, autophagy, and regulation of cell death.

Summary

Pyroptosis, a type of programmed cell death triggered by inflammation, is believed to play a role in the pathophysiology of AKI. Cumulative evidence has shown that pyroptosis is the main cause of tubular cell death in AKI. Thus, targeted intervention of pyroptosis may be a promising therapeutic approach for AKI. This review delves deep into the cutting-edge research surrounding pyroptosis in the context of AKI, shedding light on its intricate mechanisms and potential implications for clinical practice. Additionally, we explore the exciting realm of potential preclinical treatment options for AKI, aiming to pave the way for future therapeutic advancements.

Key Messages

Pyroptosis, a highly regulated form of cell death, plays a crucial role in determining the fate of cells during the development of AKI. This intricate process involves the activation of inflammasomes, which are multi-protein complexes that initiate pyroptotic cell death. By understanding the mechanisms underlying pyroptosis, researchers aim to gain insights into the pathogenesis of AKI and potentially identify new therapeutic targets for this condition.

Advancements in research on the immune-inflammatory mechanisms mediated by NLRP3 inflammasome in ischemic stroke and the regulatory role of natural plant products

Ischemic stroke (IS) is a major cause of mortality and disability among adults. Recanalization of blood vessels to facilitate timely reperfusion is the primary clinical approach; however, reperfusion itself may trigger cerebral ischemia-reperfusion injury. Emerging evidence strongly implicates the NLRP3 inflammasome as a potential therapeutic target, playing a key role in cerebral ischemia and reperfusion injury. The aberrant expression and function of NLRP3 inflammasome-mediated inflammation in cerebral ischemia have garnered considerable attention as a recent research focus. Accordingly, this review provides a comprehensive summary of the signaling pathways, pathological mechanisms, and intricate interactions involving NLRP3 inflammasomes in cerebral ischemia-reperfusion injury. Moreover, notable progress has been made in investigating the impact of natural plant products (e.g., Proanthocyanidins, methylliensinine, salidroside, α-asarone, acacia, curcumin, morin, ginsenoside Rd, paeoniflorin, breviscapine, sulforaphane, etc.) on regulating cerebral ischemia and reperfusion by modulating the NLRP3 inflammasome and mitigating the release of inflammatory cytokines. These findings aim to present novel insights that could contribute to the prevention and treatment of cerebral ischemia and reperfusion injury.

Shexiang Tongxin dropping pills protect against ischemic stroke-induced cerebral microvascular dysfunction via suppressing TXNIP/NLRP3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Patients with ischemic stroke (IS) often continue to exhibit cerebral microcirculatory dysfunction even after receiving thrombolytic therapy. Enhancing the function of cerebral microvascular endothelia represents a pivotal advancement in the therapeutic strategy for ischemic microcirculatory disturbances. A traditional Chinese medicinal formulation named Shexiang Tongxin Dropping Pills (STDP), has been clinically employed to ameliorate microcirculatory abnormalities. Existing literature attests to the beneficial role of STDP on endothelial cells (ECs). Nevertheless, specific impacts and underlying mechanisms of STDP in rectifying IS-induced cerebral microvascular dysfunction warrant further exploration.

AIM OF THE STUDY

This investigation seeks to delineate the effects of STDP on cerebral microvascular endothelial damage induced by ischemic stroke and to elucidate the underlying mechanism involved.

MATERIALS AND METHODS

Middle cerebral artery occlusion and reperfusion (MCAO/R) technique was employed to established ischemic stroke model in mice. The therapeutic efficacy of STDP on cerebral microvascular function was assessed through laser speckle contrast imaging, behavioral assays, and histological evaluations. Biochemical markers in the brain tissue, including GSH, SOD, MDA, and ROS, were quantified using specific assay kits. In vitro study, oxygen-glucose deprivation and reperfusion (OGD/R) was performed in bEnd.3 cells. The cytoprotective potential of STDP was then evaluated by measuring cell viability, LDH activity, endothelial permeability, and oxidative stress parameters. Important targets in critical pathway were verified by immunoblotting and immunofluorescence both in mice brain slices and bEnd.3 cells.

RESULTS

STDP decrease brain infarct size, repaired microvascular cerebral blood flow and attenuated neurological deficiency in MCAO/R mice. Moreover, STDP abolished MCAO/R-induced oxidative stress which was reflected by rescuing GSH content, restoration of SOD activity and T-AOC, reduction of MDA and ROS. Ex vivo, STDP increased cerebral microvascular endothelial cells viability, abolished oxidative stress and decreased their permeability after ODG/R. Mechanistically, STDP significantly suppressed endothelial ROS-TXNIP mediated the activation of NLRP3 inflammasome in vivo and in vitro.

CONCLUSION

STDP improves ischemic stroke-induced cerebral microcirculatory deficits by regulating cerebral microvascular endothelial ROS/TXNIP/NLRP3 signaling pathway.

Therapeutic strategies targeting the NLRP3‑mediated inflammatory response and pyroptosis in cerebral ischemia/reperfusion injury (Review)

Ischemic stroke poses a major threat to human health. Therefore, the molecular mechanisms of cerebral ischemia/reperfusion injury (CIRI) need to be further clarified, and the associated treatment approaches require exploration. The NOD‑like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome serves an important role in causing CIRI, and its activation exacerbates the underlying injury. Activation of the NLRP3 inflammasome triggers the maturation and production of the inflammatory molecules IL‑1β and IL‑18, as well as gasdermin‑D‑mediated pyroptosis and CIRI damage. Thus, the NLRP3 inflammasome may be a viable target for the treatment of CIRI. In the present review, the mechanisms of the NLRP3 inflammasome in the intense inflammatory response and pyroptosis induced by CIRI are discussed, and the therapeutic strategies that target the NLRP3‑mediated inflammatory response and pyroptosis in CIRI are summarized. At present, certain drugs have already been studied, highlighting future therapeutic perspectives.

Macrophage pyroptosis induced by Candida albicans

Candida albicans (C. albicans) is a prevalent opportunistic pathogen that causes mucocutaneous and systemic infections, particularly in immunocompromised individuals. Macrophages play a crucial role in eliminating C. albicans in local and bloodstream contexts, while also regulating antifungal immune responses. However, C. albicans can induce macrophage lysis through pyroptosis, a type of regulated cell death. This process can enable C. albicans to escape from immune cells and trigger the release of IL-1β and IL-18, which can impact both the host and the pathogen. Nevertheless, the mechanisms by which C. albicans triggers pyroptosis in macrophages and the key factors involved in this process remain unclear. In this review, we will explore various factors that may influence or trigger pyroptosis in macrophages induced by C. albicans, such as hypha, ergosterol, cell wall remodeling, and other virulence factors. We will also examine the possible immune response following macrophage pyroptosis.

Absence in CX3CR1 receptor signaling promotes post-ischemic stroke cognitive function recovery through suppressed microglial pyroptosis in mice

BACKGROUND

Post-stroke cognitive impairment (PSCI) is a major source of morbidity and mortality after stroke, but the pathological mechanisms remain unclear. Previous studies have demonstrated that the CX3CR1 receptor plays a crucial role in maintaining an early protective microenvironment after stroke, but whether it persistently influences cognitive dysfunction in the chronic phase requires further investigation.

METHODS

Mouse was used to establish a middle cerebral artery occlusion (MCAO)/reperfusion model to study PSCI. Cognitive function was assessed by the Morris water maze (MWM) and the novel object recognition test. Neurogenesis was assessed by immunofluorescence staining with Nestin+ /Ki67+ and DCX+ /BrdU+ double-positive cells. The cerebral damage was monitored by [18 F]-DPA-714 positron emission tomography, Nissel, and TTC staining. The pyroptosis was histologically, biochemically, and electron microscopically examined.

RESULTS

Upon MCAO, at 28 to 35 days, CX3CR1 knockout (CX3CR1-/- ) mice had better cognitive behavioral performance both in MWM and novel object recognition test than their CX3CR1+/- counterparts. Upon MCAO, at 7 days, CX3CR1-/- mice increased the numbers of Nestin+ /Ki67+ and DCX+ /BrdU+ cells, and meanwhile it decreased the protein expression of GSDMD, NLRP3 inflammasome subunit, caspase-1, mature IL-1β/IL-18, and p-P65 in the hippocampus as compared with CX3CR1+/- mice. In addition, CX3CR1-/- mice could reverse infarct volume in the hippocampus region post-stroke.

CONCLUSION

Our study demonstrated that CX3CR1 gene deletion was beneficial to PSCI recovery. The mechanism might lie in inhibited pyroptosis and enhanced neurogenesis. CX3CR1 receptor may serve as a therapeutic target for improving the PSCI.

Neuroprotective effects of Jie-du-huo-xue decoction on microglia pyroptosis after cerebral ischemia and reperfusion--From the perspective of glial-vascular unit

ETHNOPHARMACOLOGICAL RELEVANCE

Ischemic stroke poses a serious risk to public health and quality of life. Jie-Du-Huo-Xue decoction (JDHXD) is a classical and well-known Chinese formula for stroke treatment, but the pharmacological mechanism is still unclear.

AIM OF THE STUDY

This study aims to investigate the mechanism underlying microglial pyroptosis and polarization, as well as the potential efficacy of JDHXD against cerebral ischemia-reperfusion injury (CIRI).

MATERIALS AND METHODS

Models of CIRI were established by the middle cerebral artery occlusion/reperfusion (MCAO/R) method in rats. In the first stage, 36 SD rats were randomly divided into sham group, I/R group, JDHXD-L group (5.36 g/kg/day), JDHXD-M group (10.71 g/kg/day), JDHXD-H group (21.42 g/kg/day), and positive drug edaravone group. The effectiveness of JDHXD on CIRI was confirmed by neurological function testing and cerebral infarct measuring. The best dose (JDXHD-M) was subsequently chosen to perform the tests that followed. In the second stage, 36 SD rats were randomly divided into the sham group, the I/R group, and the JDHXD-M group. Detection of nerve damage using Nissl staining, proteins of pyroptosis, Iba-1, and NeuN expressions were detected by western blotting, and proteins of microglial pyroptosis and M1/M2 phenotypic polarization were detected by immunofluorescence.

RESULTS

In rats after CIRI, JDHXD significantly reduced neurological impairment and cerebral infarction. In addition, JDHXD facilitated the M1-to-M2 transition of microglia in order to minimize neuroinflammation and improve anti-inflammatory repair. In addition, JDXHD inhibited microglial pyroptosis by blocking the cleavage of caspase-1 P10 and gasdermin D, hence reducing neuronal damage and enhancing neuronal survival following reperfusion. Interestingly, JDHXD also demonstrated a protective effect on the glial-vascular unit (GVU).

CONCLUSIONS

Our investigation demonstrated that JDHXD exerted a GVU-protective effect on CIRI rats by decreasing neuroinflammation-associated microglial pyroptosis, suppressing microglial M1 activation, and promoting microglial M2 activation.

ChemR23 signaling ameliorates brain injury via inhibiting NLRP3 inflammasome-mediated neuronal pyroptosis in ischemic stroke

BACKGROUND

Inflammatory response has been recognized as a pivotal pathophysiological process during cerebral ischemia. ChemR23 signaling is involved in the pathophysiology of various inflammatory diseases. Nevertheless, the role of ChemR23 signaling in ischemic stroke remains largely unknown.

METHODS

Permanent ischemic stroke mouse model was accomplished by middle cerebral artery occlusion (MCAO). Resolvin E1 (RvE1) or chemerin-9 (C-9), the agonists of ChemR23, were administered by intracerebroventricular (i.c.v) injection before MCAO induction. Then, analysis of neurobehavioral deficits and brain sampling were done at Day 1 after MCAO. The brain samples were further analyzed by histological staining, immunofluorescence, RNA sequencing, ELISA, transmission electron microscope, and western blots. Furthermore, oxygen-glucose deprivation (OGD) was employed in SH-SY5Y to mimic MCAO in vitro, and ChemR23 signaling pathway was further studied by overexpression of ChemR23 or administration of related agonists or antagonists. Analysis of cell death and related pathway markers were performed.

RESULTS

ChemR23 expression was upregulated following MCAO. Under in vitro and in vivo ischemic conditions, ChemR23 deficiency or inhibition contributed to excessive NLRP3-mediated maturation and release of IL-1β and IL-18, as well as enhanced cleavage of GSDMD-N and neuronal pyroptosis. These influences ultimately aggravated brain injury and neuronal damage. On the other hand, ChemR23 activation by RvE1 or C-9 mitigated the above pathophysiological abnormalities in vivo and in vitro, and overexpression of ChemR23 in SH-SY5Y cells also rescued OGD-induced neuronal pyroptosis. Blockade of NLRP3 mimics the protective effects of ChemR23 activation in vitro.

CONCLUSION

Our data indicated that ChemR23 modulates NLRP3 inflammasome-mediated neuronal pyroptosis in ischemic stroke. Activation of ChemR23 may serve as a promising potential target for neuroprotection in cerebral ischemia.

Impact of cholesterol homeostasis within cochlear cells on auditory development and hearing loss

Cholesterol is the most abundant sterol molecule in mammalian cells, which not only constitutes the cell membrane but also plays essential roles in the synthesis of important hormones, synapse formation, and cell signal transduction. The effect of hypercholesterolemia on hearing has been studied extensively, and multiple studies have demonstrated that hypercholesterolemia is a risk factor for hearing loss. However, the impact of cholesterol homeostasis within auditory cells on peripheral auditory development and maintenance has not been evaluated in detail. Mutations in certain cholesterol metabolism-related genes, such as NPC1, SERAC1, DHCR7, and OSBPL2, as well as derivatives of cholesterol metabolism-related ototoxic drugs, such as β-cyclodextrin, can lead to disruptions of cholesterol homeostasis within auditory cells, resulting in hearing loss. This article aims to review the impact of cholesterol homeostasis within auditory cells on the peripheral auditory function from the following two perspectives: (1) changes in cholesterol homeostasis regulatory genes in various hearing loss models; (2) mechanisms underlying the effects of some drugs that have a therapeutic effect on hearing loss via regulating cholesterol homeostasis. This article aims to summarize and analyze the impact of disruption of cellular cholesterol homeostasis within auditory cells on hearing, in order to provide evidence regarding the underlying mechanisms.

Role of NLRP3 Inflammasome in Stroke Pathobiology: Current Therapeutic Avenues and Future Perspective

Neuroinflammation is a key pathophysiological feature of stroke-associated brain injury. A local innate immune response triggers neuroinflammation following a stroke via activating inflammasomes. The nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome has been heavily implicated in stroke pathobiology. Following a stroke, several stimuli have been suggested to trigger the assembly of the NLRP3 inflammasome. Recent studies have advanced the understanding and revealed several new players regulating NLRP3 inflammasome-mediated neuroinflammation. This article discussed recent advancements in NLRP3 assembly and highlighted stroke-induced mitochondrial dysfunction as a major checkpoint to regulating NLRP3 activation. The NLRP3 inflammasome activation leads to caspase-1-dependent maturation and release of IL-1β, IL-18, and gasdermin D. In addition, genetic or pharmacological inhibition of the NLRP3 inflammasome activation and downstream signaling has been shown to attenuate brain infarction and improve the neurological outcome in experimental models of stroke. Several drug-like small molecules targeting the NLRP3 inflammasome are in different phases of development as novel therapeutics for various inflammatory conditions, including stroke. Understanding how these molecules interfere with NLRP3 inflammasome assembly is paramount for their better optimization and/or development of newer NLRP3 inhibitors. In this review, we summarized the assembly of the NLRP3 inflammasome and discussed the recent advances in understanding the upstream regulators of NLRP3 inflammasome-mediated neuroinflammation following stroke. Additionally, we critically examined the role of the NLRP3 inflammasome-mediated signaling in stroke pathophysiology and the development of therapeutic modalities to target the NLRP3 inflammasome-related signaling for stroke treatment.

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.

Mechanisms of PANoptosis and relevant small-molecule compounds for fighting diseases

Pyroptosis, apoptosis, and necroptosis are mainly programmed cell death (PCD) pathways for host defense and homeostasis. PANoptosis is a newly distinct inflammatory PCD pathway that is uniquely regulated by multifaceted PANoptosome complexes and highlights significant crosstalk and coordination among pyroptosis (P), apoptosis (A), and/or necroptosis(N). Although some studies have focused on the possible role of PANpoptosis in diseases, the pathogenesis of PANoptosis is complex and underestimated. Furthermore, the progress of PANoptosis and related agonists or inhibitors in disorders has not yet been thoroughly discussed. In this perspective, we provide perspectives on PANoptosome and PANoptosis in the context of diverse pathological conditions and human diseases. The treatment targeting on PANoptosis is also summarized. In conclusion, PANoptosis is involved in plenty of disorders including but not limited to microbial infections, cancers, acute lung injury/acute respiratory distress syndrome (ALI/ARDS), ischemia-reperfusion, and organic failure. PANoptosis seems to be a double-edged sword in diverse conditions, as PANoptosis induces a negative impact on treatment and prognosis in disorders like COVID-19 and ALI/ARDS, while PANoptosis provides host protection from HSV1 or Francisella novicida infection, and kills cancer cells and suppresses tumor growth in colorectal cancer, adrenocortical carcinoma, and other cancers. Compounds and endogenous molecules focused on PANoptosis are promising therapeutic strategies, which can act on PANoptosomes-associated members to regulate PANoptosis. More researches on PANoptosis are needed to better understand the pathology of human conditions and develop better treatment.

Hypoxia Inducible Factor-1α Through ROS/NLRP3 Pathway Regulates the Mechanism of Acute Ischemic Stroke Microglia Scorching Mechanism

Purpose

In vitro experiments explored how the hypoxia-induced factor-1α (HIF-1α) regulates the regulation of pyroptosis in microglial cells (BV 2) in acute ischemic stroke through ROS/NLRP3 pathway.

Methods

The microglia acute phase oxygen-glucose deprivation/reoxygenation (OGD/R) was established, CCK-8 was applied to determine the optimal timing of intervention modeling. HIF-1α was overexpressed with stabilizer GF-4592 and HIF-1α small molecule interfering RNA (HIF-1α-siRNA), which was divided into group A (blank group), group B (OGD/R model group), group C (model+FG-4592 intervention group), group D (model+siRNA negative control group) and group E (model+HIF-1α-siRNA group). Cell proliferation of different groups was measured by CCK-8 assay. Pyroptosis and intracellular ROS levels were measured by flow cell technology. IL-18, IL-1β levels were measured by ELISA. HIF-1α, GSDMD-D, GSDMD-N, clean-Caspase-1 and NLRP3 protein expression levels were measured by Western blot. On the above experiments, ROS and NLRP3 response experiments were performed to explore how HIF-1α regulates pyroptosis through ROS/NLRP3 pathway.

Results

Hypoxia for 6 h then reoxygenation for 12 h was the optimal intervention time. Compared with groups B and D, cell proliferation in group C was significantly enhanced, pyroptosis, intracellular levels of ROS, IL-18, IL-1β and the expression of GSDMD-D, GSDMD-N, clean-Caspase-1, and NLRP3 proteins were significantly decreased in group C (P < 0.05). However, in group E, the performance of these test indicators were exactly the opposite, and the difference was statistically significant (P < 0.05). Through ROS and NLRP3 response experiments, it was found that HIF-1α Inhibition of Pyroptosis by inhibiting ROS/NLRP3 pathway.

Conclusion

Overexpression of HIF-1α factor can inhibit microglia pyroptosis. HIF-1α factor has an inhibitory effect on the ROS/NLRP 3 pathway, which can inhibit the pyroptotic process in microglia.

Genetic insights into the association of statin and newer nonstatin drug target genes with human longevity: a Mendelian randomization analysis

BACKGROUND

It remains controversial whether the long-term use of statins or newer nonstatin drugs has a positive effect on human longevity. Therefore, this study aimed to investigate the genetic associations between different lipid-lowering therapeutic gene targets and human longevity.

METHODS

Two-sample Mendelian randomization analyses were conducted. The exposures comprised genetic variants that proxy nine drug target genes mimicking lipid-lowering effects (LDLR, HMGCR, PCKS9, NPC1L1, APOB, CETP, LPL, APOC3, and ANGPTL3). Two large-scale genome-wide association study (GWAS) summary datasets of human lifespan, including up to 500,193 European individuals, were used as outcomes. The inverse-variance weighting method was applied as the main approach. Sensitivity tests were conducted to evaluate the robustness, heterogeneity, and pleiotropy of the results. Causal effects were further validated using expression quantitative trait locus (eQTL) data.

RESULTS

Genetically proxied LDLR variants, which mimic the effects of lowering low-density lipoprotein cholesterol (LDL-C), were associated with extended lifespan. This association was replicated in the validation set and was further confirmed in the eQTL summary data of blood and liver tissues. Mediation analysis revealed that the genetic mimicry of LDLR enhancement extended lifespan by reducing the risk of major coronary heart disease, accounting for 22.8% of the mediation effect. The genetically proxied CETP and APOC3 inhibitions also showed causal effects on increased life expectancy in both outcome datasets. The lipid-lowering variants of HMGCR, PCKS9, LPL, and APOB were associated with longer lifespans but did not causally increase extreme longevity. No statistical evidence was detected to support an association between NPC1L1 and lifespan.

CONCLUSION

This study suggests that LDLR is a promising genetic target for human longevity. Lipid-related gene targets, such as PCSK9, CETP, and APOC3, might potentially regulate human lifespan, thus offering promising prospects for developing newer nonstatin therapies.

The CXCL12-CXCR4-NLRP3 axis promotes Schwann cell pyroptosis and sciatic nerve demyelination in rats

Studies have shown that the activation of the NOD-like receptor protein 3 (NLRP3) inflammasome is detrimental to the functional recovery of the sciatic nerve, but the regulatory mechanisms of the NLRP3 inflammasome in peripheral nerves are unclear. C-X-C motif chemokine 12 (CXCL12) can bind to C-X-C chemokine receptor type 4 (CXCR4) and participate in a wide range of nerve inflammation by regulating the NLRP3 inflammasome. Based on these, we explore whether CXCL12-CXCR4 axis regulates the NLRP3 inflammasome in the peripheral nerve. We found that CXCR4/CXCL12, NLRP3 inflammasome-related components, pyroptosis-related proteins and inflammatory factors in the sciatic nerve injured rats were markedly increased compared with the sham-operated group. AMD3100, a CXCR4 antagonist, reverses the activation of NLRP3 inflammasome, Schwann cell pyroptosis and sciatic nerve demyelination. We further treated rat Schwann cells with LPS (lipopolysaccharide) and adenosine triphosphate (ATP) to mimic the cellular inflammation model of sciatic nerve injury, and the results were consistent with those in vivo. In addition, both in vivo and in vitro experiments demonstrated that AMD3100 treatment reduced the phosphorylation of nuclear factor κB (NF-κB) and the expression of thioredoxin interacting protein (TXNIP), which contributes to activating NLRP3 inflammasome. Therefore, our findings suggest that, after sciatic nerve injury, CXCL12-CXCR4 axis may promote Schwann cell pyroptosis and sciatic nerve demyelination through activating NLRP3 inflammasome and slow the recovery process of the sciatic nerve.

Regulated necrosis pathways: a potential target for ischemic stroke

Globally, ischemic stroke causes millions of deaths per year. The outcomes of ischemic stroke are largely determined by the amount of ischemia-related and reperfusion-related neuronal death in the infarct region. In the infarct region, cell injuries follow either the regulated pathway involving precise signaling cascades, such as apoptosis and autophagy, or the nonregulated pathway, which is uncontrolled by any molecularly defined effector mechanisms such as necrosis. However, numerous studies have recently found that a certain type of necrosis can be regulated and potentially modified by drugs and is nonapoptotic; this type of necrosis is referred to as regulated necrosis. Depending on the signaling pathway, various elements of regulated necrosis contribute to the development of ischemic stroke, such as necroptosis, pyroptosis, ferroptosis, pathanatos, mitochondrial permeability transition pore-mediated necrosis and oncosis. In this review, we aim to summarize the underlying molecular mechanisms of regulated necrosis in ischemic stroke and explore the crosstalk and interplay among the diverse types of regulated necrosis. We believe that targeting these regulated necrosis pathways both pharmacologically and genetically in ischemia-induced neuronal death and protection could be an efficient strategy to increase neuronal survival and regeneration in ischemic stroke.

ChemR23 activation attenuates cognitive impairment in chronic cerebral hypoperfusion by inhibiting NLRP3 inflammasome-induced neuronal pyroptosis

Neuroinflammation plays critical roles in vascular dementia (VaD), the second leading cause of dementia, which can be induced by chronic cerebral hypoperfusion (CCH). NLRP3 inflammasome-induced pyroptosis, the inflammatory programmed cell death, has been reported to contribute to the development of VaD. ChemR23 is a G protein-coupled receptor that has emerging roles in regulating inflammation. However, the role of ChemR23 signalling in NLRP3 inflammasome-induced pyroptosis in CCH remains elusive. In this study, a CCH rat model was established by permanent bilateral common carotid artery occlusion (BCCAO) surgery. Eight weeks after the surgery, the rats were intraperitoneally injected with the ChemR23 agonist Resolvin E1 (RvE1) or chemerin-9 (C-9). Additionally, primary rat hippocampal neurons and SH-SY5Y cells were adopted to mimic CCH injury in vitro. Our results showed that the levels of ChemR23 expression were decreased from the 8th week after BCCAO, accompanied by significant cognitive impairment. Further analysis revealed that CCH induced neuronal damage, synaptic injury and NLRP3-related pyroptosis activation in hippocampal neurons. However, pharmacologic activation of ChemR23 with RvE1 or C-9 counteracted these changes. In vitro experiments also showed that ChemR23 activation prevented primary neuron pyroptosis induced by chronic hypoxia. In addition, manipulating ChemR23 expression markedly regulated NLRP3 inflammasome-induced neuronal pyroptosis through PI3K/AKT/Nrf2 signalling in SH-SY5Y cells under hypoglycaemic and hypoxic conditions. Collectively, our data demonstrated that ChemR23 activation inhibits NLRP3 inflammasome-induced neuronal pyroptosis and improves cognitive function via the PI3K/AKT/Nrf2 signalling pathway in CCH models. ChemR23 may serve as a potential novel therapeutic target to treat CCH-induced cognitive impairment.

ErbB4 processing is involved in OGD/R induced neuron injury

OBJECTIVE

Our previous study found that ErbB4 gene expression was changed after oxygen-glucose deprivation/reperfusion (OGD/R). However, the exact role and mechanism of ErbB4 in brain ischemia are largely unknown. In this study, we explored the protective effects of ErbB4 and its possible mechanism after OGD/R.

METHODS

Cerebral ischemia/reperfusion (I/R) injury model was established in vitro and in vivo. Cell viability, apoptosis, and ROS production were measured by MTT, TUNEL, and fluorescent probe 2', 7'-dichlorofluorescein diacetate (DCFH-DA). Infarct size was evaluated by TTC. We performed bioinformatics analyses to screen for novel key genes involved in ErbB4 changes. RNA-Seq was used to transcriptome analysis. RNA and protein expression were detected by quantitative RT‒PCR and western bloting.

RESULTS

The expression of 80-kDa ErbB4 decreased after cerebral I/R injury in vitro and in vivo. Co-expression network analysis revealed that ErbB4 expression was correlated with the changes in Adrb1, Adrb2, Ldlr, and Dab2. Quantitative RT‒PCR revealed that the mRNA expression levels of Adrb1, Adrb2, and Dab2 were upregulated, and that of Ldlr was decreased after OGD/R. Activation of ErbB4 expression by neuregulin 1 (NRG1) significantly promoted cell survival, attenuated hippocampal apoptosis, and decreased ROS production after OGD/R. Furthermore, the elimination of ErbB4 using a specific siRNA reversed these beneficial effects.

CONCLUSION

Our data revealed the neuroprotective effects of ErbB4 against OGD/R injury, and the action could be related to changes in the ErbB4 membrane-associated fragment and the expression of Adrb1, Adrb2, Ldlr, and Dab2.

Scientific Landscape of Oxidative Stress in Stroke: From a Bibliometric Analysis to an in-Depth Review

Stroke is an acute cerebrovascular disease resulting from either obstruction or rupture of a blood vessel in the brain. Oxidative stress (OS), referred to a status where cellular oxidative capacities overwhelm antioxidative defenses, is involved in the pathophysiology of stroke. The bibliometric analysis and in-depth review aim to depict the research trend of OS in stroke. Relevant scientific publications were acquired from the Web of Science Core Collection database. Scientific landscape of OS in stroke was illustrated by general quantitative trend, impactful journals, and co-authorship of various academic units (i.e., countries/regions, organizations, and authors). Furthermore, theme analysis predicting the hot research issues and frontiers was performed. 15,826 documents regarding OS in stroke were obtained over a time span of more than 20 years from 1992 to 2021. The overall tendency of publication counts was continuously on the rise. Bibliometric analysis indicated China and the United States were predominant in this study field, as reflected by their high publication counts and intensive collaboration with other countries. Current key research areas of OS in stroke may lie in the investigation of neuroinflammation, and interaction among multiple cell death mechanisms including apoptosis, autophagy, and ferroptosis to search for effective treatments. Moreover, another hot topic could be the association between air pollution and stroke, and its underlying mechanisms. As the exploration of OS in stroke is speculated to be a continuous hot spot in the future, this article may be helpful for researchers to conduct future studies with the understanding of influential academic forces and research highlights.

ALDH2 activation attenuates oxygen-glucose deprivation/reoxygenation-induced cell apoptosis, pyroptosis, ferroptosis and autophagy

PURPOSE

It is previously reported that aldehyde dehydrogenase 2 family member (ALDH2) shows neuroprotective effects in cerebral ischemia/reperfusion injury. However, whether the protective effects are through mediating the programmed cell death is yet to be fully elucidated.

METHODS

In vitro oxygen-glucose deprivation/reoxygenation (OGD/R) model was established in HT22 cells and mouse cortical neurons. Subsequently, ALDH2 expression were assessed by qRT-PCR and western blot. The methylation status was examined by methylation-specific PCR (MS-PCR). Then, ALDH2 expression was promoted and suppressed to explore the role of ALDH2 in OGD/R-treated cells. CCK-8 assay was applied to detect cell viability, and flow cytometry was applied to evaluate cell apoptosis. Western blot was applied to detect the apoptosis-related proteins (Caspase 3, Bcl-2 and Bax), necroptosis-related proteins (RIP3 and MLKL), pyroptosis-related proteins (NLRP3 and GSDMD), ferroptosis-related protein (ACSL4 and GPX4), and autophagy-related proteins (LC3B, and p62). IL-1β and IL-18 production was evaluated by ELISA assay. Reactive oxygen species production and Fe2+ content were evaluated by the corresponding detection kit.

RESULTS

In OGD/R-treated cells, ALDH2 expression was decreased, which was due to the hypermethylation of ALDH2 in the promoter region. ALDH2 overexpression improved cell viability and ALDH2 knockdown suppressed cell viability in OGD/R-treated cells. We also found that ALDH2 overexpression attenuated OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy, while ALDH2 knockdown facilitated the OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy.

CONCLUSIONS

Collectively, our results implied that ALDH2 attenuated OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy to promote cell viability in HT22 cells and mouse cortical neurons.

Pharmacological intervention of curcumin via the NLRP3 inflammasome in ischemic stroke

Ischemic-induced neuronal injury arises due to low oxygen/nutrient levels and an inflammatory response that exacerbates neuronal loss. NOD-like receptor family pyrin domain-containing 3 (NLRP3) is an important regulator of inflammation after ischemic stroke, with its inhibition being involved in nerve regeneration. Curcumin, a main active ingredient in Chinese herbs, plays a positive role in neuronal repair and neuroprotection by regulating the NLRP3 signaling pathway. Nevertheless, the signaling mechanisms relating to how curcumin regulates NLRP3 inflammasome in inflammation and neural restoration following ischemic stroke are unknown. In this report, we summarize the main biological functions of the NLRP3 inflammasome along with the neuroprotective effects and underlying mechanisms of curcumin via impairment of the NLRP3 pathway in ischemic brain injury. We also discuss the role of medicinal interventions that target the NLRP3 and potential pathways, as well as possible directions for curcumin therapy to penetrate the blood-brain barrier (BBB) and hinder inflammation in ischemic stroke. This report conclusively demonstrates that curcumin has neuroprotective properties that inhibit inflammation and prevent nerve cell loss, thereby delaying the progression of ischemic brain damage.

Research progress of NLRP3 inflammasome and its inhibitors with aging diseases

In recent years, a new target closely linked to a variety of diseases has appeared in the researchers' vision, which is the NLRP3 inflammasome. With the deepening of the study of NLRP3 inflammasome, it was found that it plays an extremely important role in a variety of physiological pathological processes, and NLRP3 inflammasome was also found to be associated with some age-related diseases. It is associated with the development of insulin resistance, Alzheimer's disease, Parkinson's, cardiovascular aging, hearing and vision loss. At present, the only clinical approach to the treatment of NLRP3 inflammasome-related diseases is to use anti-IL-1β antibodies, but NLRP3-specific inhibitors may be better than the IL-1β antibodies. This article reviews the relationship between NLRP3 inflammasome and aging diseases: summarizes some of the relevant experimental results reported in recent years, and introduces the biological signals or pathways closely related to the NLRP3 inflammasome in a variety of aging diseases, and also introduces some promising small molecule inhibitors of NLRP3 inflammasome for clinical treatment, such as: ZYIL1, DFV890 and OLT1177, they have excellent pharmacological effects and good pharmacokinetics.

Trends in NLRP3 inflammasome research in ischemic stroke from 2011 to 2022: A bibliometric analysis

BACKGROUND

Ischemic stroke is a leading cause of permanent disability and death globally. The nucleotide-biding oligomaerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a multi-protein complex that plays a role in ischemic stroke. Recently, research on the role of NLRP3 in ischemic stroke has developed rapidly worldwide. However, there is no bibliometric analysis of NLRP3 in ischemic stroke to date.

AIM

Through bibliometric analysis, the aim of this study was to assess the current state of research on NLRP3 in the field of ischemic stroke research worldwide over the past 12 years and to identify important results, major research areas, and emerging trends.

METHODS

Publications related to NLRP3 in ischemic stroke from January 1, 2011 to December 31, 2022 were obtained from the Web of Science Core Collection (WoSCC). We used HistCite, VOSviewer, CiteSpace, and Bibliometrix for bibliometric analysis and visualization. The Total Global Citation Score (TGCS) was employed to assess the impact of publications.

RESULTS

We found that research of NLRP3 in ischemic stroke developed rapidly starting in 2011. 601 relevant studies have been published in 245 journals over the past 12 years. Journal of Neuroinflammation and International Immunopharmacology were the most productive journals and Journal of Neuroinflammation was the most cited journal. Additionally, Stroke and Journal of Cerebral Blood Flow & Metabolism were the most co-cited journal. The most productive country was China (records = 430) and the most productive university was the Zhejiang University (records = 24). Arumugam TV (TGCS = 949) was the most cited author in this field. NLRP3 inflammasome activation, nf-κb, oxidative stress, and inflammation were the knowledge bases for the research in this field.

CONCLUSION

This study is a scientometric study utilizing quantitative and qualitative methods to comprehensively review the publications on NLRP3 in ischemic stroke. This information provides a reference for scholars to further study NLRP3 in ischemic stroke.

Research progress on the mechanism of curcumin in cerebral ischemia/reperfusion injury: a narrative review

Cerebral ischemia/reperfusion (I/R) injury can result in different levels of cerebral impairment, and in severe cases, death. Curcumin, an essential bioactive component of turmeric, has a rich history as a traditional medicine for various ailments in numerous countries. Experimental and clinical research has established that curcumin offers a protective effect against cerebral I/R injury. Curcumin exerts its protective effects by acting on specific mechanisms such as antioxidant, anti-inflammatory, inhibition of ferroptosis and pyroptosis, protection of mitochondrial function and structure, reduction of excessive autophagy, and improvement of endoplasmic reticulum (ER) stress, which ultimately help to preserve the blood-brain barrier (BBB) and reducing apoptosis. There is currently a shortage of drugs undergoing clinical trials for the treatment of cerebral I/R injury, highlighting the pressing need for research and development of novel treatments to address this injury. The primary objective of this study is to establish a theoretical basis for future clinical applications of curcumin by delineating the mechanisms and protective effects of curcumin against cerebral I/R injury. Adapted with permission from [1].

BDE-47 flame retardant exposure induces microglial pyroptosis and cognitive deficits by activating the mtROS-NLRP3 axis via Sirt3 downregulation and is salvaged by honokiol

The brominated flame retardant 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) is widely distributed in the environment and poses a certain risk to human health. Studies have reported that oxidative stress is a key mechanism underlying BDE-47-induced neurotoxicity. Mitochondrial reactive oxygen species (mtROS) is a crucial mediator of NLRP3 inflammasome activation, which is involved in cognitive dysfunction induced by environmental toxins. However, the function of the mtROS-NLRP3 inflammasome pathway in BDE-47-elicited cognitive deficits and the underlying mechanisms remain elusive. Our data illustrated that eight weeks of BDE-47 (20 mg/kg) gavage led to cognitive deficits and hippocampal neuronal injury in mice. BDE-47 exposure downregulated Sirt3 expression and decreased the activity and expression level of SOD2, thereby inhibiting mtROS scavenging and activating NLRP3 inflammasome-mediated pyroptosis in the mouse hippocampus and BV-2 cells. In vitro, BDE-47-evoked microglial pyroptosis relied on NLRP3 inflammasome activation. Moreover, a mtROS scavenger (TEMPO) attenuated NLRP3 inflammasome activation and subsequent microglial pyroptosis under BDE-47 stress. Furthermore, Sirt3 overexpression restored the activity and expression of SOD2 and enhanced mtROS scavenging, thereby suppressing NLRP3 inflammasome activation and ameliorating microglial pyroptosis. Notably, honokiol (HKL), a pharmacological agonist of Sirt3, mitigated BDE-47-evoked hippocampal neuronal injury and cognitive impairment by inhibiting mtROS-NLRP3 axis-mediated pyroptosis via Sirt3 upregulation.

Role of NLRP3 inflammasome-mediated neuronal pyroptosis and neuroinflammation in neurodegenerative diseases

BACKGROUND

Neurodegenerative diseases are a common group of neurological disorders characterized by progressive loss of neuronal structure and function leading to cognitive impairment. Recent studies have shown that neuronal pyroptosis mediated by the NLRP3 inflammasome plays a crucial role in the pathogenesis of neurodegenerative diseases.

OBJECTIVE AND METHOD

The NLRP3 inflammasome is a multiprotein complex that, when activated within cells, triggers an inflammatory response, ultimately leading to pyroptotic cell death of neurons. Pyroptosis is a typical pro-inflammatory programmed cell death process occurring downstream of NLRP3 inflammasome activation, characterized by the formation of pores on the cell membrane by the GSDMD protein, leading to cell lysis and the release of inflammatory factors. It has been found that NLRP3 inflammasome-mediated neuronal pyroptosis is closely associated with the development of various neurodegenerative diseases, such as Alzheimer's disease, traumatic brain injury, and Parkinson's disease. Therefore, inhibiting NLRP3 inflammasome activation and attenuating neuronal pyroptosis could potentially serve as novel strategies for the treatment of neurodegenerative diseases.

RESULTS

The aim of this review is to explore the role of NLRP3 activation-mediated neuronal pyroptosis and neuroinflammation in neurodegenerative diseases. Firstly, we extensively discuss the relationship between NLRP3 inflammasome-mediated neuronal pyroptosis and neuroinflammation in various neurodegenerative diseases. Subsequently, we further explore the mechanisms driving NLRP3 activation and assembly, as well as the post-translational modifications regulating NLRP3 inflammasome activation.

CONCLUSION

Understanding these mechanisms will contribute to a deeper understanding of the link between neuronal pyroptosis and neurodegenerative diseases, and hold significant implications for the treatment and prevention of neurodegenerative diseases.

Biliverdin modulates the Nrf2/A20/eEF1A2 axis to alleviate cerebral ischemia-reperfusion injury by inhibiting pyroptosis

This study aimed to examine whether Biliverdin, which is a common metabolite of haem, can alleviate cerebral ischemia reperfusion injury (CIRI) by inhibiting pyroptosis. Here, CIRI was induced by middle cerebral artery occlusion-reperfusion (MCAO/R) in C57BL/6 J mice and modelled by oxygen and glucose deprivation/reoxygenation (OGD/R) in HT22 cells, it was treated with or without Biliverdin. The spatiotemporal expression of GSDMD-N and infarction volumes were assessed by immunofluorescence staining and triphenyltetrazolium chloride (TTC), respectively. The NLRP3/Caspase-1/GSDMD pathway, which is central to the pyroptosis process, as well as the expression of Nrf2, A20, and eEF1A2 were determined by Western-blots. Nrf2, A20, and eEF1A2 interactions were verified using dual-luciferase reporter assays, chromatin immunoprecipitation, or co-immunoprecipitation. Additionally, the role of Nrf2/A20/eEF1A2 axis in modulating the neuroprotective properties of Biliverdin was investigated using A20 or eEF1A2 gene interference (overexpression and/or silencing). 40 mg/kg of Biliverdin could significantly alleviate CIRI both in vivo and in vitro, promoted the activation of Nrf2, elevated A20 expression, but decreased eEF1A2 expression. Nrf2 can bind to the promoter of A20, thereby transcriptionally regulating the expression of A20. A20 can furthermore interacted with eEF1A2 through its ZnF4 domain to ubiquitinate and degrade it, leading to the downregulation of eEF1A2. Our studies have also demonstrated that either the knock-down of A20 or over-expression of eEF1A2 blunted the protective effect of Biliverdin. Rescue experiments further confirmed that Biliverdin could regulate the NF-κB pathway via the Nrf2/A20/eEF1A2 axis. In summary, our study demonstrates that Biliverdin ameliorates CIRI by inhibiting the NF-κB pathway via the Nrf2/A20/eEF1A2 axis. Our findings can help identify novel therapeutic targets for the treatment of CIRI.

NLRP3 inflammasome activation after ischemic stroke

Cerebral ischemia is a pathological condition resulting from the cessation or reduction of blood supply to the cerebral arteries. Neurological deficits that are clinically relevant can arise as a result of brain damage. The etiology of stroke is multifaceted and intricate, with the inflammatory response being a crucial component that warrants significant attention. Following a cerebrovascular accident, the levels of interleukin-1 beta and interleukin-18 within the central nervous system escalate due to the activation of the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 inflammasome. The inflammation is aggravated by the subsequent occurrence of pyroptosis. The mechanisms that activate the NLRP3 inflammasome pyroptosis signaling pathway axis are described in this article. In addition, we go over how pyroptosis interacts with other processes for regulated cell death. In addition, specific NLRP3 inflammasome pathway inhibitors are identified, which offer new approaches to preventing ischemic brain injury.

GABAB Receptor Activation Attenuates Neuronal Pyroptosis in Post-cardiac Arrest Brain Injury

Brain injury is a major cause of death and disability after cardiac arrest (CA). Previous studies have shown that activating GABAB receptors significantly improves neurological function after CA, but the mechanism of this neuronal protection of damaged neurons remains unclear. Thus, the present study aimed to investigate whether GABAB receptor activation protects against neuronal injury and to reveal the underlying protective mechanisms. In this study, rats underwent 10 min of asphyxia to induce CA, and SH-SY5Y cells were subjected to oxygen and glucose deprivation/reoxygenation (OGD/R) to establish in vivo and in vitro models of hypoxic neuronal injury. Differential gene expression between CA rats and sham-operated rats was identified using RNA-seq. TUNEL and Nissl staining were used to evaluate cortical neuron damage, while Western blotting, qRT-PCR, and immunofluorescence assays were conducted to measure pyroptosis-related indicators. Furthermore, cellular models with high expression of caspase-11 were established to reveal the novel molecular mechanisms by which GABAB receptor activation exerts neuroprotective effects. Intriguingly, our results showed that caspase-11 and GSDMD were highly expressed in rats experiencing cardiac arrest. Specifically, GSDMD was expressed in neurons in the M1 area of the cerebral cortex. Moreover, activation of the GABAB receptor exerted a protective effect on neurons both in vivo and in vitro. Baclofen attenuated caspase-11 activation and neuronal pyroptosis after CA, and the anti-neuronal pyroptosis effect of baclofen was abolished by overexpression of caspase-11 in neuronal cells. In conclusion, GABAB receptor activation may play a neuroprotective role by alleviating neuronal pyroptosis through a mechanism involving caspase-11.

Lipocalin-2-mediated astrocyte pyroptosis promotes neuroinflammatory injury via NLRP3 inflammasome activation in cerebral ischemia/reperfusion injury

BACKGROUND

Neuroinflammation is a vital pathophysiological process during ischemic stroke. Activated astrocytes play a major role in inflammation. Lipocalin-2 (LCN2), secreted by activated astrocytes, promotes neuroinflammation. Pyroptosis is a pro-inflammatory form of programmed cell death that has emerged as a new area of research in stroke. Nevertheless, the potential role of LCN2 in astrocyte pyroptosis remains unclear.

METHODS

An ischemic stroke model was established by middle cerebral artery occlusion (MCAO) in vivo. In this study, in vitro, oxygen-glucose deprivation and reoxygenation (O/R) were applied to cultured astrocytes. 24p3R (the LCN2 receptor) was inhibited by astrocyte-specific adeno-associated virus (AAV-GFAP-24p3Ri). MCC950 and Nigericin sodium salt (Nig) were used to inhibit or promote the activation of NLRP3 inflammasome pharmacologically, respectively. Histological and biochemical analyses were performed to assess astrocyte and neuron death. Additionally, the neurological deficits of mice were evaluated.

RESULTS

LCN2 expression was significantly induced in astrocytes 24 h after stroke onset in the mouse MCAO model. Lcn2 knockout (Lcn2^-/-) mice exhibited reduced infarct volume and improved neurological and cognitive functions after MCAO. LCN2 and its receptor 24p3R were colocalized in astrocytes. Mechanistically, suppression of 24p3R by AAV-GFAP-24p3Ri alleviated pyroptosis-related pore formation and the secretion of pro-inflammatory cytokines via LCN2, which was then reversed by Nig-induced NLRP3 inflammasome activation. Astrocyte pyroptosis was exacerbated in Lcn2^-/- mice by intracerebroventricular administration of recombinant LCN2 (rLCN2), while this aggravation was restricted by blocking 24p3R or inhibiting NLRP3 inflammasome activation with MCC950.

CONCLUSION

LCN2/24p3R mediates astrocyte pyroptosis via NLRP3 inflammasome activation following cerebral ischemia/reperfusion injury.

The role of pyroptosis in cognitive impairment

Cognitive impairment is a major global disease, manifests as a decline in cognitive functioning and endangers the health of the population worldwide. The incidence of cognitive impairment has increased rapidly with an increasingly aging population. Although the mechanisms of cognitive impairment have partly been elucidated with the development of molecular biological technology, treatment methods are very limited. As a unique form of programmed cell death, pyroptosis is highly pro-inflammatory and is closely associated with the incidence and progression of cognitive impairment. In this review, we discuss the molecular mechanisms of pyroptosis briefly and the research progress on the relationship between pyroptosis and cognitive impairment and its potential therapeutic values, to provide a reference for research in the field of cognitive impairment.

Transmission of NLRP3-IL-1β Signals in Cerebral Ischemia and Reperfusion Injury: from Microglia to Adjacent Neuron and Endothelial Cells via IL-1β/IL-1R1/TRAF6

The pyrin domain-containing protein 3 (NLRP3) inflammasome drives the profound cerebral ischemia and reperfusion injury (I/R) and mediates the secretion of IL-1β (interleukin-1β), which exerts a subsequent cascade of inflammatory injury. The NLRP3-activated-microglial manipulation in adjacent neuronal and endothelial NLRP3 activation has been confirmed in our previous studies. In the present study, we extended the cognition of how microglia mediated neuronal and endothelial NLRP3-IL-1β signaling during cerebral ischemia and reperfusion injury. In vitro, Neuro-2a and bEND3 cells were cultured alone or co-cultured with BV2 cells and oxygen-glucose deprivation/reoxygenation (OGD/R) was performed. In vivo, transient middle cerebral artery occlusion (tMCAO) rat models and lentiviral silencing targeting IL-1R1 were performed. The NLRP3 inflammasome activation was evaluated by enzyme-linked immunosorbent assay, western blotting, immunoprecipitation, immunohistochemistry, and immunofluorescence. In the co-culture system after OGD/R treatment, NLRP3 inflammasomes in neurons and endothelial cells were activated by microglial IL-1β via IL-1β/IL-1R1/TRAF6 signaling pathway, with the basal protein level of NLRP3. In addition, ruptured lysosomes engulfing ASC specks which were possibly secreted from microglia triggered the enhanced NLRP3 expression. In cortices of tMCAO rats at 24 h of reperfusion, silencing IL-1R1, mainly presented in neurons and endothelial cells, was efficient to block the subsequent inflammatory damage and leukocyte brain infiltration, leading to better neurological outcome. Neuronal and endothelial NLRP3 inflammasomes were activated by microglia in cerebral ischemia and reperfusion injury mainly via IL-1β/IL-1R1/TRAF6 signaling, which might be therapeutically targetable.

A Lipid Perspective on Regulated Pyroptosis

Pyroptosis is a novel pro-inflammatory cell programmed death dependent on Gasdermin (GSMD) family-mediated membrane pore formation and subsequent cell lysis, accompanied by the release of inflammatory factors and expanding inflammation in multiple tissues. All of these processes have impacts on a variety of metabolic disorders. Dysregulation of lipid metabolism is one of the most prominent metabolic alterations in many diseases, including the liver, cardiovascular system, and autoimmune diseases. Lipid metabolism produces many bioactive lipid molecules, which are important triggers and endogenous regulators of pyroptosis. Bioactive lipid molecules promote pyroptosis through intrinsic pathways involving reactive oxygen species (ROS) production, endoplasmic reticulum (ER) stress, mitochondrial dysfunction, lysosomal disruption, and the expression of related molecules. Pyroptosis can also be regulated during the processes of lipid metabolism, including lipid uptake and transport, de novo synthesis, lipid storage, and lipid peroxidation. Taken together, understanding the correlation between lipid molecules such as cholesterol and fatty acids and pyroptosis during metabolic processes can help to gain insight into the pathogenesis of many diseases and develop effective strategies from the perspective of pyroptosis.

Lactate dehydrogenase A mediated histone lactylation induced the pyroptosis through targeting HMGB1

Cerebral ischemia (CI), as the cerebrovascular disease with the highest incidence rate, is treated by limited intravenous thrombolysis and intravascular therapy to recanalize the embolized vessels. Recently, the discovery of histone lactylation proposes a potential molecular mechanism for the role of lactate in physiological and pathological processes. This study aimed to analyze the lactate dehydrogenase A (LDHA) mediated histone lactylation in CI reperfusion (CI/R) injury. Oxygen-glucose deprivation/reoxygenation (OGD/R) treated N2a cells and middle cerebral artery occlusion (MCAO) treated rats was used as the CI/R model in vivo and in vitro. Cell viability and pyroptosis was assessed using CCK-8 and flow cytometry. RT-qPCR was performed to detect the relative expression. The relationship between histone lactylation and HMGB1 was verified by CHIP assay. LDHA, HMGB1, lactate and histone lactylation was up-regulated in the OGD/R treated N2a cells. Additionally, LDHA knockdown decreased HMGB1 levels in vitro, and relieved CI/R injury in vivo. Besides, LDHA silencing declined the histone lactylation mark enrichment on HMGB1 promoter, and lactate supplement rescued it. What?s more, LDHA knockdown decreased the IL-18 and IL-1β contents, and the cleaved-caspase-1 and GSDMD-N protein levels in the OGD/R treated N2a cells, which was reversed by HMGB1 overexpression. Knockdown of LDHA suppressed the pyroptosis in the N2a cells induced by OGD/R, which was reversed by HMGB1 overexpression. Mechanistically, LDHA mediated the histone lactylation induced pyroptosis through targeting HMGB1 in the CI/R injury.

A Preclinical Systematic Review and Meta-Analysis of Behavior Testing in Mice Models of Ischemic Stroke

Stroke remains one of the most important causes of death and disability. Preclinical research is a powerful tool for understanding the molecular and cellular response to stroke. However, a lack of standardization in animal evaluation does not always ensure reproducible results. In the present study, we wanted to identify the best strategy for evaluating animal behavior post-experimental stroke. As such, a meta-analysis was made, evaluating behavioral tests done on male C57BL/6 mice subjected to stroke or sham surgery. Overall, fifty-six studies were included. Our results suggest that different types of tests should be used depending on the post-stroke period one needs to analyze. In the hyper-acute, post-stroke period, the best quantifier will be animal examination scoring, as it is a fast and inexpensive way to identify differences between groups. When evaluating stoke mice in the acute phase, a mix of animal examination and motor tests that focus on movement asymmetry (foot-fault and cylinder testing) seem to have the best chance of picking up differences between groups. Complex tasks (the rotarod test and Morris water maze) should be used within the chronic phase to evaluate differences between the late-subacute and chronic phases.

NLRP3 inflammasome inhibitor MCC950 reduces cerebral ischemia/reperfusion induced neuronal ferroptosis

The role of nucleotide-binding oligomerization domainlike receptor pyrin domain containing 3 (NLRP3) inflammasome in cerebral ischemia-reperfusion (I/R) induced neuroinflammation and neuronal pyroptosis has been widely recognized. Latest studies revealed that NLRP3 inflammasome engage in not only pyroptosis but also other types of cell death. Ferroptosis has been proved to be closely associated with cerebral I/R injury. In this study, our objectives were to verify the inhibitory effect of the NLRP3-specific inhibitor MCC950 on cerebral I/R-mediated neuronal pyroptosis, and to explore the regulation and possible mechanism of MCC950 on cerebral I/R-mediated neuronal ferroptosis. Our data showed that the NLRP3-specific inhibitor, MCC950, effectively reversed the I/R-mediated NLRP3 inflammasome activation and neuronal pyroptosis. Furthermore, we found that I/R increased iron concentrations and levels of malondialdehyde (MDA), downregulated glutathione peroxidase 4 (GPX4) expression, and upregulated long chain fatty acid-CoA ligase 4 (FACL4) and prostaglandin endoperoxide synthase 2 (PTGS2) expression. Interestingly, these changes were also reversed by the MCC950. Finally, in vitro, we found that MCC950 significantly reduced ROS levels in OGD/R treated HT22 cells. In conclusion, pharmaceutical inhibition of NLRP3 by MCC950 attenuates I/R-induced neuronal ferroptosis, possibly by reducing ROS accumulation.