Ablation of caspase-1 protects against TBI-induced pyroptosis in vitro and in vivo

Dexmedetomidine enhances Mitophagy via PINK1 to alleviate hippocampal neuronal Pyroptosis and improve postoperative cognitive dysfunction in elderly rat

Postoperative cognitive dysfunction (POCD) is a common complication in elderly surgical patients, significantly affecting their quality of life. Dexmedetomidine (Dex), an anesthetic, has shown promise in alleviating POCD, but its underlying mechanism remains unclear. This study aims to explore how Dex improves POCD in aged rats by targeting the PINK1-mediated mitochondrial autophagy pathway, reducing caspase-1/11-GSDMD-induced hippocampal neuronal pyroptosis. Transcriptome sequencing identified 300 differentially expressed genes enriched in the mitochondrial autophagy pathway in Dex-treated POCD rat hippocampal tissue, with Pink1 as a key candidate. In a POCD rat model, Dex treatment upregulated hippocampal PINK1 expression. In vitro experiments using H19-7 rat hippocampal neurons revealed that Dex enhanced mitochondrial autophagy and suppressed neuronal pyroptosis by upregulating PINK1. Further mechanistic validation demonstrated that Dex activated PINK1-mediated mitochondrial autophagy, inhibiting caspase-1/11-GSDMD-induced neuronal pyroptosis. In vivo experiments confirmed Dex's ability to reduce caspase-1/11-GSDMD-dependent hippocampal neuronal pyroptosis and improve postoperative cognitive function in aged rats. Dexmedetomidine improves postoperative cognitive dysfunction in elderly rats by enhancing mitochondrial autophagy via PINK1 upregulation, mitigating caspase-1/11-GSDMD-induced neuronal pyroptosis.

Hyperbaric oxygen therapy attenuates heatstroke-induced hippocampal injury by inhibiting microglial pyroptosis

Background: Central nervous system (CNS) injury is the most prominent feature of heatstroke and the hippocampus is prone to damage. However, the mechanisms underlying the heatstroke-induced hippocampal injury remain unclear. Hyperbaric oxygen (HBO) therapy prevents CNS injury in heatstroke mice. However, the underlying mechanisms of HBO in heatstroke-induced hippocampal injury remain unclear. This study aimed to elucidate the protective effects of HBO against hippocampal injury and its potential role in microglial pyroptosis in heatstroke rats.Methods: A rat heatstroke model and a heat stress model with a mouse microglial cell line (BV2) were, respectively, used to illustrate the effect of HBO on heat-induced microglial pyroptosis in vivo and in vitro. We used a combination of molecular and histological methods to assess microglial pyroptosis and neuroinflammation both in vivo and in vitro.Results: The results revealed that HBO improved heatstroke-induced survival outcomes, hippocampal injury, and neurological dysfunction in rats. In addition, HBO mitigates microglial pyroptosis and reduces the expression of pro-inflammatory cytokines in the hippocampus of heatstroke rats. In vitro experiments showed that HBO attenuated BV2 cell injury under heat stress. Furthermore, HBO prevented heat-induced pyroptosis of BV2 cells, and the expression of pro-inflammatory cytokines IL-18 and IL-1β was reduced. Mechanistically, HBO alleviates heatstroke-induced neuroinflammation and hippocampal injury by preventing microglial pyroptosis. Conclusions: In conclusion, HBO attenuates heatstroke-induced neuroinflammation and hippocampal injury by inhibiting microglial pyroptosis.

Recent advances on signaling pathways and their inhibitors in spinal cord injury

Spinal cord injury (SCI) is a serious and disabling central nervous system injury. Its complex pathological mechanism can lead to sensory and motor dysfunction. It has been reported that signaling pathway plays a key role in the pathological process and neuronal recovery mechanism of SCI. Such as PI3K/Akt, MAPK, NF-κB, and Wnt/β-catenin signaling pathways. According to reports, various stimuli and cytokines activate these signaling pathways related to SCI pathology, thereby participating in the regulation of pathological processes such as inflammation response, cell apoptosis, oxidative stress, and glial scar formation after injury. Activation or inhibition of relevant pathways can delay inflammatory response, reduce neuronal apoptosis, prevent glial scar formation, improve the microenvironment after SCI, and promote neural function recovery. Based on the role of signaling pathways in SCI, they may be potential targets for the treatment of SCI. Therefore, understanding the signaling pathway and its inhibitors may be beneficial to the development of SCI therapeutic targets and new drugs. This paper mainly summarizes the pathophysiological process of SCI, the signaling pathways involved in SCI pathogenesis, and the potential role of specific inhibitors/activators in its treatment. In addition, this review also discusses the deficiencies and defects of signaling pathways in SCI research. It is hoped that this study can provide reference for future research on signaling pathways in the pathogenesis of SCI and provide theoretical basis for SCI biotherapy.

Hemorrhagic Shock and Resuscitation Causes Excessive Dopaminergic Signaling in the mPFC and Cognitive Dysfunction

Peri-operative hemorrhagic shock and resuscitation (HSR), a severe traumatic stress, is closely associated with post-operative anxiety, depression, and cognitive dysfunction, subsequently causing a serious burden on families and society. Following the co-release of corticotropin-releasing factor and catecholamine, traumatic stress activates dopaminergic neurons, increasing the addictive behavior and neurocognitive impairment risks. This study investigates the association between cognitive dysfunction and dopaminergic neurons in the mPFC under HSR conditions. This study established an HSR model by bleeding and re-transfusion in the mice. After HSR exposure, a dopamine D1 receptor antagonist, SKF-83566, was administered intraperitoneally for three consecutive days. Novel object recognition (NOR), conditioned fearing (FC), and conditioned place preference (CPP) were used to assess cognitive changes 16 days after HSR exposure. Local field potential (LFP) in the mPFC was also investigated during the novel object exploration. Compared with the mice exposed to sham, there was a significant decrease in the object recognition index, a reduction in context- and tone-related freezing time, an increase in CPP values, a downregulation of β-power but upregulation of γ-power in the mPFC in the mice exposed to HSR. Moreover, the mice exposed to HSR showed significantly upregulated TH-positive cell number, cleaved caspase-1- and TH-positive cells, and interleukin (IL)-1β/18 expression in the mPFC compared with sham; SKF-83566 could partially reverse these alternations. The HSR caused excessive dopaminergic signaling and cognitive dysfunction in the mPFC, a condition that might be ameliorated using a dopamine D1 receptor inhibitor.

Targeted Therapy of Spinal Cord Injury: Inhibition of Apoptosis Is a Promising Therapeutic Strategy

Spinal cord injury (SCI) is a serious disabling central nervous system injury that can lead to motor, sensory, and autonomic dysfunction below the injury level. SCI can be divided into primary injury and secondary injury according to pathological process. Primary injury is mostly irreversible, while secondary injury is a dynamic regulatory process. Apoptosis is an important pathological event of secondary injury and has a significant effect on the recovery of nerve function after SCI. Nerve cell death can further aggravate the microenvironment of the injured site, leading to neurological dysfunction and thus affect the clinical outcome of patients. Therefore, apoptosis plays a crucial role in the pathological progression of secondary SCI, while inhibiting apoptosis may be a promising therapeutic strategy for SCI. This review will summarize and explore the factors that lead to cell death after SCI, the influence of cross talk between signaling pathways and pathways involved in apoptosis and discuss the influence of apoptosis on SCI, and the therapeutic significance of targeting apoptosis on SCI. This review helps us to understand the role of apoptosis in secondary SCI and provides a theoretical basis for the treatment of SCI based on apoptosis.

Effects of Isoflurane on the Cell Pyroptosis in the Lung Cancer Through the HMGB1/RAGE Pathway

There are many common malignant tumors in clinic. Among them, lung cancer is caused by the failure of suction system, which seriously threatens the life safety of patients. Recent studies have found that anesthetics have achieved certain efficacy in many cancers. Isoflurane, an inhaled anesthetic, is used in this study to explore whether it can prevent the lung cancer development. The A549 and H1299 were purchased. Cell viability was tested by CCK-8 experiment. Cell death and pyroptosis were analyzed by PI staining as well as flow cytometry. HMGB1 as well as RAGE protein levels were tested by Western blot. The same is true of pyroxin-related proteins. The HMGB1 as well as RAGE levels in the lung cancer tissues were determined by Western blot along with immunohistochemistry. Isoflurane treatment can reduce cell viability and promote cell pyroptosis. Additionally, the protein levels of cleaved caspase-1, IL-1β, GSDMD-N, NLRP3, HMGB1, and RAGE were dramatically up-regulated in the lung cancer after isoflurane treatment. Down-regulated proteins in lung cancer tissues include HMGB1 and RAGE proteins. After HMGB1 knockdown or FPS-ZM1 treatment, the role of isoflurane in the lung cancer was neutralized. This study demonstrated that isoflurane induced the cell pyroptosis in the lung cancer through activating the HMGB1/RAGE pathway.

NLRP3-mediated periodontal ligament cell pyroptosis promotes root resorption

AIM

To investigate the mechanisms by which periodontal ligament cells (PDLCs) convert biomechanical stimulation into inflammatory microenvironment inducing root resorption (RR).

MATERIALS AND METHODS

RNA sequencing was employed to explore mechanisms in force-inflammatory signal transduction. Then resorption volume, odontoclastic activity, PDLC pyroptotic ratio and NOD-like receptor protein 3 (NLRP3)-mediated pyroptosis pathway activation were analysed under force and pyroptosis inhibition. Further osteoclast formation, macrophage number and transwell polarization demonstrated the effects of PDLC pyroptosis on osteoclastogenesis and M1 polarization.

RESULTS

RNA sequencing revealed that NLRP3-mediated PDLC pyroptosis induced by Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NFκB)/NLRP3 pathway may be involved in mechano-inflammatory signal transduction. PDLC pyroptosis under force and the expression of NLRP3-mediated pyroptosis pathway in force-enhanced PDLCs were significantly increased, both in vivo and in vitro. MCC950 administration was sufficient to reduce PDLC pyroptosis and alleviate RR, odontoclast formation and M1 polarization in vivo. Further in vitro exploration showed that MCC950 treatment reduced PDLC force-promoted pyroptosis and blocked NLRP3-mediated pyroptosis pathway. Moreover, by treating THP-1 with force-pretreated PDLCs or supernatants, NLRP3-mediated PDLC pyroptotic released products induced osteoclast formation and M1 polarization.

CONCLUSIONS

NLRP3-mediated PDLC pyroptosis promotes RR. PDLCs transmit excessive force into inflammation signals through TLR4/NFκB/NLRP3 pathway, inducing PDLC pyroptosis, which directly promotes odontoclast formation and subsequent RR or promotes M1 polarization to indirectly trigger odontoclastogenesis and RR.

Fluoride promotes the secretion of inflammatory factors in microglia through NLRP3/Caspase-1/GSDMD pathway

It is widespread of endemic fluorosis in China, and the exposure of excessive fluoride will cause nervous system disease and activate microglia. However, the mechanism of the damage is not clear. It is well-known that NLRP3/Caspase-1/GSDMD pathway, a classic pyroptosis pathway, is widely involved in the occurrence and development of nervous system-related diseases, infectious diseases, and atherosclerotic diseases. This research aimed to explore the molecular mechanism of sodium fluoride on inflammation and pyroptosis in BV2 microglia based on the NLRP3/Caspase-1/GSDMD signaling pathway. BV2 microglia was treated with sodium fluoride at the dose of 0.25, 1, and 2 mmol/L for 24, 48, and 72 h, respectively. Cell viability, cell morphology, lactate dehydrogenase content, and related proteins and genes were examined to investigate if sodium fluoride caused damage to BV2 microglia through the pyroptosis pathway. Dithiolam (5 μmol/L), a pyroptosis inhibitor, was added for further verification. NaF could induced BV2 cells injury in a dose-dependent fashion through disrupting the integrity of cell membranes and increasing IL-1β via upregulating NLRP3, Caspase-1, and its downstream protein GSDMD. Disulfiram could improve these changes caused by NaF. In conclusion, our results suggested that NLRP3/Caspase-1/GSDMD-mediated classical pyroptosis pathway was involved in fluoride-induced BV2 microglia damage.

VX-765 Alleviates Circadian Rhythm Disorder in a Rodent Model of Traumatic Brain Injury Plus Hemorrhagic Shock and Resuscitation

Severe traumatic brain injury (TBI) can result in persistent complications, including circadian rhythm disorder, that substantially affect not only the injured people, but also the mood and social interactions with the family and the community. Pyroptosis in GFAP-positive astrocytes plays a vital role in inflammatory changes post-TBI. We determined whether VX-765, a low molecular weight caspase-1 inhibitor, has potential therapeutic value against astrocytic inflammation and pyroptosis in a rodent model of TBI plus hemorrhagic shock and resuscitation (HSR). A weight-drop plus bleeding and refusion model was used to establish traumatic exposure in rats. VX-765 (50 mg/kg) was injected via the femoral vein after resuscitation. Wheel-running activity was assessed, brain magnetic resonance images were evaluated, the expression of pyroptosis-associated molecules including cleaved caspase-1, gasdermin D (GSDMD), and interleukin-18 (IL-18) in astrocytes in the region of anterior hypothalamus, were explored 30 days post-trauma. VX-765-treated rats had significant improvement in circadian rhythm disorder, decreased mean diffusivity (MD) and mean kurtosis (MK), increased fractional anisotropy (FA), an elevated number and branches of astrocytes, and lower cleaved caspase-1, GSDMD, and IL-18 expression in astrocytes than TBI + HSR-treated rats. These results demonstrated that inhibition of pyroptosis-associated astrocytic activations in the anterior hypothalamus using VX-765 may ameliorate circadian rhythm disorder after trauma. In conclusion, we suggest that interventions targeting caspase-1-induced astrocytic pyroptosis by VX-765 are promising strategies to alleviate circadian rhythm disorder post-TBI.

Erythropoietin alleviates astrocyte pyroptosis by targeting the miR-325-3p/Gsdmd axis in rat spinal cord injury

BACKGROUND

Neuroinflammation plays an important role in spinal cord injury (SCI), and an increasing number of studies have focused on the role of astrocytes in neuroinflammation. Pyroptosis is an inflammation-related form of programmed cell death, and neuroinflammation induced by astrocytes in the form of pyroptosis has been widely reported in many central nervous system diseases. Recent studies have found that erythropoietin has significant anti-inflammatory and neuroprotective effects in SCI; however, it has not been reported whether erythropoietin can reduce neuroinflammation by inhibiting neural cell pyroptosis in SCI.

METHODS

A GEO dataset (GSE153720) was used to analyse the expression of pyroptosis-related genes in sham astrocytes and astrocytes 7 days, 1 month and 3 months after SCI. TargetScan and miRDB databases were used to predict the miRNA that could bind to the 3'UTR of rat Gsdmd. Primary rat spinal astrocytes were used for in vitro experiments, and the modified version of Allen's method was used to establish the rat SCI model. Western blotting, quantitative real-time polymerase chain reaction, flow cytometry, immunofluorescence, lactate dehydrogenase release assay and propidium iodide staining were used to detect the pyroptosis phenotype. A dual luciferase reporter gene assay was used to verify that miR-325-3p can bind to the 3'UTR of Gsdmd.

RESULTS

We found that pyroptosis-related genes mediated by the canonical NLRP3 inflammasome were highly expressed in astrocytes in an SCI animal model by bioinformatic analysis. We also observed that erythropoietin could reduce astrocyte pyroptosis in vivo and in vitro. In addition, we predicted miRNAs that regulate Gsdmd, the pyroptosis executor, and verified that erythropoietin inhibits astrocyte pyroptosis in SCI through the miR-325-3p/Gsdmd axis.

CONCLUSIONS

We demonstrated that erythropoietin can inhibit astrocyte pyroptosis through the miR-325-3p/Gsdmd axis. This study is expected to provide a new mechanism for erythropoietin in the treatment of SCI and a more reliable theoretical basis for clinical research.

[Effects of VX765 on osteoarthritis and chondrocyte inflammation in rats]

Objective

To investigate the effects and underlying mechanisms of VX765 on osteoarthritis (OA) and chondrocytes inflammation in rats.

Methods

Chondrocytes were isolated from the knee joints of 4-week-old Sprague Dawley (SD) rats. The third-generation cells were subjected to cell counting kit 8 (CCK-8) analysis to assess the impact of various concentrations (0, 1, 5, 10, 20, 50, 100 μmol/L) of VX765 on rat chondrocyte activity. An in vitro lipopolysaccharide (LPS) induced cell inflammation model was employed, dividing cells into control group, LPS group, VX765 concentration 1 group and VX765 concentration 2 group without obvious cytotoxicity. Western blot, real-time fluorescence quantitative PCR, and ELISA were conducted to measure the expression levels of inflammatory factors-transforming growth factor β 1 (TGF-β 1), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α). Additionally, Western blot and immunofluorescence staining were employed to assess the expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1). Thirty-two SD rats were randomly assigned to sham surgery group (group A), OA group (group B), OA+VX765 (50 mg/kg) group (group C), and OA+VX765 (100 mg/kg) group (group D), with 8 rats in each group. Group A underwent a sham operation with a medial incision, while groups B to D underwent additional transverse incisions to the medial collateral ligament and anterior cruciate ligament, with removal of the medial meniscus. One week post-surgery, groups C and D were orally administered 50 mg/kg and 100 mg/kg VX765, respectively, while groups A and B received an equivalent volume of saline. Histopathological examination using HE and safranin-fast green staining was performed, and Mankin scoring was utilized for evaluation. Immunohistochemical staining technique was employed to analyze the expressions of matrix metalloproteinase 13 (MMP-13) and collagen type Ⅱ.

Results

The CCK-8 assay indicated a significant decrease in cell viability at VX765 concentrations exceeding 10 μmol/L ( P<0.05), so 4 μmol/L and 8 μmol/L VX765 without obvious cytotoxicity were selected for subsequent experiments. Following LPS induction, the expressions of TGF-β 1, IL-6, and TNF-α in cells significantly increased when compared with the control group ( P<0.05). However, intervention with 4 μmol/L and 8 μmol/L VX765 led to a significant decrease in expression compared to the LPS group ( P<0.05). Western blot and immunofluorescence staining demonstrated a significant upregulation of Nrf2 pathway-related molecules Nrf2 and HO-1 protein expressions by VX765 ( P<0.05), indicating Nrf2 pathway activation. Histopathological examination of rat knee joint tissues and immunohistochemical staining revealed that, compared to group B, treatment with VX765 in groups C and D improved joint structural damage in rat OA, alleviated inflammatory reactions, downregulated MMP-13 expression, and increased collagen type Ⅱ expression.

Conclusion

VX765 can improve rat OA and reduce chondrocyte inflammation, possibly through the activation of the Nrf2 pathway.

Targeting pyroptosis with nanoparticles to alleviate neuroinflammatory for preventing secondary damage following traumatic brain injury

Posttraumatic neuroinflammation is a key driver of secondary injury after traumatic brain injury (TBI). Pyroptosis, a proinflammatory form of programmed cell death, considerably activates strong neuroinflammation and amplifies the inflammatory response by releasing inflammatory contents. Therefore, treatments targeting pyroptosis may have beneficial effects on the treatment of secondary brain damage after TBI. Here, a cysteine-alanine-glutamine-lysine peptide-modified β-lactoglobulin (β-LG) nanoparticle was constructed to deliver disulfiram (DSF), C-β-LG/DSF, to inhibit pyroptosis and decrease neuroinflammation, thereby preventing TBI-induced secondary injury. In the post-TBI mice model, C-β-LG/DSF selectively targets the injured brain, increases DSF accumulation, and extends the time of the systemic circulation of DSF. C-β-LG/DSF can alleviate brain edema and inflammatory response, inhibit secondary brain injury, promote learning, and improve memory recovery in mice after trauma. Therefore, this study likely provided a potential approach for reducing the secondary spread of TBI.

Strategies for gaseous neuromodulator release in chemical neuroscience: Experimental approaches and translational validation

Gasotransmitters are a group of short-lived gaseous signaling molecules displaying diverse biological functions depending upon their localized concentration. Nitric oxide (NO), hydrogen sulfide (H2S), and carbon monoxide (CO) are three important examples of endogenously produced gasotransmitters that play a crucial role in human neurophysiology and pathogenesis. Alterations in their optimal physiological concentrations can lead to various severe pathophysiological consequences, including neurological disorders. Exogenous administration of gasotransmitters has emerged as a prominent therapeutic approach for treating such neurological diseases. However, their gaseous nature and short half-life limit their therapeutic delivery. Therefore, developing synthetic gasotransmitter-releasing strategies having control over the release and duration of these gaseous molecules has become imperative. However, the complex chemistry of synthesis and the challenges of specific quantified delivery of these gases, make their therapeutic application a challenging task. This review article provides a focused overview of emerging strategies for delivering gasotransmitters in a controlled and sustained manner to re-establish neurophysiological homeostasis.

HET0016 inhibits neuronal pyroptosis in the immature brain post-TBI via the p38 MAPK signaling pathway

Traumatic brain injury (TBI) is a serious health threat worldwide, especially for the younger demographic. Our previous study demonstrated that HET0016 (a specific inhibitor of 20-hydroxyeicosatetraenoic acid synthesis) can decrease the lesion volume in the immature brain post-TBI; however, its mechanism of action and its association with pyroptosis post-TBI are unclear. In this study, we established a controlled cortical impact (CCI) injury rat model (postnatal day 9-10) and observed that increased expression of indicators for pyroptosis, including NLR family pyrin domain containing 3 (NLRP3), caspase-1 and gasdermin D (GSDMD) proteins and interleukin (IL)-18/IL-1β mRNA during the acute phase of TBI, especially on post-injury day (PID) 1. Additionally, we found that caspase-1 was primarily expressed in the neurons and microglia. HET0016 (1 mg/kg/d, ip, 3 consecutive days since TBI) reduced the lesion volume; neuronal death; expression of NLRP3, caspase-1, and GSDMD; and expression of IL-18/IL-1β mRNA. Bioinformatics analysis suggested involvement of mitogen-activated protein kinase (MAPK) signaling pathway in the HET0016-mediated neuroprotective role against TBI in the immature brain. Western blot analysis revealed reduced expression of p-p38 MAPK and nuclear factor-kappa B (NF-κB) p65 in the neurons and microglia upon HET0016 treatment in TBI rats. In cultured primary cortical neurons subjected to oxygen-glucose deprivation/re-oxygenation (OGD) + (lipopolysaccharide) LPS, HET0016-induced the reduction of p-p38 MAPK, NLRP3, cleaved-caspase-1, GSDMD, IL-18, and IL-1β was reversed by co-treatment with p38 MAPK activator as well as NLRP3 agonist. Therefore, we conclude that pyroptosis is involved in neuronal death in the immature brains post-TBI and that HET0016 administration can alleviate neuronal pyroptosis possibly via inhibiting the phosphorylation of p38 MAPK.

Remote limb ischemic postconditioning inhibits microglia pyroptosis by modulating HGF after acute ischemia stroke

The repetitive inflation-deflation of a blood pressure cuff on a limb is known as remote limb ischemic postconditioning (RIPostC). It prevents brain damage induced by acute ischemia stroke (AIS). Pyroptosis, executed by the pore-forming protein gasdermin D (GSDMD), is a type of regulated cell death triggered by proinflammatory signals. It contributes to the pathogenesis of ischemic brain injury. However, the effects of RIPostC on pyroptosis following AIS remain largely unknown. In our study, linear correlation analysis confirmed that serum GSDMD levels in AIS patients upon admission were positively correlated with NIHSS scores. RIPostC treatment significantly reduced GSDMD level compared with patients without RIPostC at 3 days post-treatment. Besides, middle cerebral artery occlusion (MCAO) surgery was performed on C57BL/6 male mice and RIPostC was induced immediately after MCAO. We found that RIPostC suppressed the activation of NLRP3 inflammasome to reduce the maturation of GSDMD, leading to decreased pyroptosis in microglia after AIS. Hepatocyte growth factor (HGF) was identified using the high throughput screening. Importantly, HGF siRNA, exogenous HGF, and ISG15 siRNA were used to reveal that HGF/ISG15 is a possible mechanism of RIPostC regulation in vivo and in vitro.

Elamipretide reduces pyroptosis and improves functional recovery after spinal cord injury

AIMS

Elamipretide (EPT), a novel mitochondria-targeted peptide, has been shown to be protective in a range of diseases. However, the effect of EPT in spinal cord injury (SCI) has yet to be elucidated. We aimed to investigate whether EPT would inhibit pyroptosis and protect against SCI.

METHODS

After establishing the SCI model, we determined the biochemical and morphological changes associated with pyroptosis, including neuronal cell death, proinflammatory cytokine expression, and signal pathway levels. Furthermore, mitochondrial function was assessed with flow cytometry, quantitative real-time polymerase chain reaction, and western blot.

RESULTS

Here, we demonstrate that EPT improved locomotor functional recovery following SCI as well as reduced neuronal loss. Moreover, EPT inhibited nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasome activation and pyroptosis occurrence and decreased pro-inflammatory cytokines levels following SCI. Furthermore, EPT alleviated mitochondrial dysfunction and reduced mitochondrial reactive oxygen species level.

CONCLUSION

EPT treatment may protect against SCI via inhibition of pyroptosis.

Recent Progress of Copper-Based Nanomaterials in Tumor-Targeted Photothermal Therapy/Photodynamic Therapy

Nanotechnology, an emerging and promising therapeutic tool, may improve the effectiveness of phototherapy (PT) in antitumor therapy because of the development of nanomaterials (NMs) with light-absorbing properties. The tumor-targeted PTs, such as photothermal therapy (PTT) and photodynamic therapy (PDT), transform light energy into heat and produce reactive oxygen species (ROS) that accumulate at the tumor site. The increase in ROS levels induces oxidative stress (OS) during carcinogenesis and disease development. Because of the localized surface plasmon resonance (LSPR) feature of copper (Cu), a vital trace element in the human body, Cu-based NMs can exhibit good near-infrared (NIR) absorption and excellent photothermal properties. In the tumor microenvironment (TME), Cu2+ combines with H2O2 to produce O2 that is reduced to Cu1+ by glutathione (GSH), causing a Fenton-like reaction that reduces tumor hypoxia and simultaneously generates ROS to eliminate tumor cells in conjunction with PTT/PDT. Compared with other therapeutic modalities, PTT/PDT can precisely target tumor location to kill tumor cells. Moreover, multiple treatment modalities can be combined with PTT/PDT to treat a tumor using Cu-based NMs. Herein, we reviewed and briefly summarized the mechanisms of actions of tumor-targeted PTT/PDT and the role of Cu, generated from Cu-based NMs, in PTs. Furthermore, we described the Cu-based NMs used in PTT/PDT applications.

A study on the level of NLRP3 inflammasome in patients with premature rupture of membranes

OBJECTIVE

In this study, we investigated the levels of interleukin-1β (IL-1β), IL-18, and the NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome in patients with premature rupture of membranes (PROMs).

METHODS

We selected 60 pregnant women at the Fourth Hospital of Baotou between January 2019 and July 2021. These women were divided into three distinct groups: the preterm PROM group with 20 cases, term PROM (TPROM) group with 20 cases, and a control group with 20 cases consisting of normal full-term pregnancies without PROM. Peripheral blood was collected from all participants. Using enzyme-linked immunosorbent assay, the levels of IL-1 and IL-18 in the plasma were assessed. Additionally, the proportions of NLRP3, apoptosis-associated speck-like protein (ASC), and caspase-1-positive macrophages were also evaluated.

RESULTS

The ratios of NLRP3, ASC, IL-1β, and IL-18 concentrations, along with the presence of caspase-1-positive macrophages, were notably greater in the PROM groups in comparison with the control group (p < .05). In the TPROM group and control group, the proportions of IL-1β and IL-18 levels were found to be lower than NLRP3, ASC, and caspase-1-positive macrophages levels (p < .05).

CONCLUSION

The concentrations of IL-1β and IL-18, as well as the ratios of NLRP3, ASC, and caspase-1-positive macrophages, were elevated in patients with PROM compared to the control group. This suggests a potential correlation between the excessive activation of NLRP3 and the development of PROM.

Curcumin in vitro Neuroprotective Effects Are Mediated by p62/keap-1/Nrf2 and PI3K/AKT Signaling Pathway and Autophagy Inhibition

Oxidative stress and autophagy are potential mechanisms associated with cerebral ischemia/reperfusion injury (IRI) and is usually linked to inflammatory responses and apoptosis. Curcumin has recently been demonstrated to exhibit anti-inflammatory, anti-oxidant, anti-apoptotic and autophagy regulation properties. However, mechanism of curcumin on IRI-induced oxidative stress and autophagy remains not well understood. We evaluated the protective effects and potential mechanisms of curcumin on cerebral microvascular endothelial cells (bEnd.3) and neuronal cells (HT22) against oxygen glucose deprivation/reoxygenation (OGD/R) in vitro models that mimic in vivo cerebral IRI. The cell counting kit-8 (CCK-8) and lactate dehydrogenase (LDH) activity assays revealed that curcumin attenuated the OGD/R-induced injury in a dose-specific manner. OGD/R induced elevated levels of inflammatory cytokines TNF-alpha, IL-6 as well as IL-1beta, and these effects were notably reduced by curcumin. OGD/R-mediated apoptosis was suppressed by curcumin via upregulating B-cell lymphoma-2 (Bcl-2) and downregulating Bcl-associated X (Bax), cleaved-caspase3 and TUNEL apoptosis marker. Additionally, curcumin increased superoxide dismutase (SOD) and glutathione (GSH), but suppressed malondialdehyde (MDA) and reactive oxygen species (ROS) content. Curcumin inhibited the levels of autophagic biomarkers such as LC3 II/LC3 I and Beclin1. Particularly, curcumin induced p62 accumulation and its interactions with keap1 and promoted NF-E2-related factor 2 (Nrf2) translocation to nucleus, accompanied by increased NADPH quinone dehydrogenase (Nqo1) and heme oxygenase 1 (HO-1). Treatment of curcumin increased phosphorylation-phosphatidylinositol 3 kinase (p-PI3K) and p-protein kinase B (p-AKT). The autophagy inhibitor 3-methyladenine (3-MA) activated the keap-1/Nrf2 and PI3K/AKT pathways. This study highlights the neuroprotective effects of curcumin on cerebral IRI.

GSDMD knockdown attenuates phagocytic activity of microglia and exacerbates seizure susceptibility in TLE mice

BACKGROUND

Temporal lobe epilepsy (TLE) is often characterized pathologically by severe neuronal loss in the hippocampus. Phagocytic activity of microglia is essential for clearing apoptotic neuronal debris, allowing for repair and regeneration. Our previous research has shown that gasdermin D (GSDMD)-mediated pyroptosis is involved in the pathogenesis of TLE. However, whether GSDMD-mediated pyroptosis influences the accumulation of apoptotic neurons remains unclear. Therefore, the present study was designed to investigate whether phagocytic activity of microglia is involved in GSDMD-mediated pyroptosis and the pathogenesis of TLE.

METHODS

To establish a TLE model, an intra-amygdala injection of kainic acid (KA) was performed. The Racine score and local field potential (LFP) recordings were used to assess seizure severity. Neuronal death in the bilateral hippocampus was assessed by Nissl staining and TUNEL staining. Microglial morphology and phagocytic activity were detected by immunofluorescence and verified by lipopolysaccharide (LPS) and the P2Y12R agonist 2MeSADP.

RESULTS

GSDMD knockdown augmented the accumulation of apoptotic neurons and seizure susceptibility in TLE mice. Microglia activated and transition to the M1 type with increased pro-inflammatory cytokines. Furthermore, GSDMD knockdown attenuated the migration and phagocytic activity of microglia. Of note, LPS-activated microglia attenuated seizure susceptibility and the accumulation of apoptotic neurons in TLE after GSDMD knockdown. A P2Y12R selective agonist, 2MeSADP, enhanced the migration and phagocytic activity of microglia.

CONCLUSIONS

Our results demonstrate that GSDMD knockdown exacerbates seizure susceptibility and the accumulation of apoptotic neurons by attenuating phagocytic activity of microglia. These findings suggest that GSDMD plays a protective role against KA-induced seizure susceptibility.

Armcx1 attenuates secondary brain injury in an experimental traumatic brain injury model in male mice by alleviating mitochondrial dysfunction and neuronal cell death

Armcx1 is highly expressed in the brain and is located in the mitochondrial outer membrane of neurons, where it mediates mitochondrial transport. Mitochondrial transport promotes the removal of damaged mitochondria and the replenishment of healthy mitochondria, which is essential for neuronal survival after traumatic brain injury (TBI). This study investigated the role of Armcx1 and its potential regulator(s) in secondary brain injury (SBI) after TBI. An in vivo TBI model was established in male C57BL/6 mice via controlled cortical impact (CCI). Adeno-associated viruses (AAVs) with Armcx1 overexpression and knockdown were constructed and administered to mice via stereotactic cortical injection. Exogenous miR-223-3p mimic or inhibitor was transfected into cultured cortical neurons, which were then scratched to simulate TBI in vitro. It was found that Armcx1 expression decreased significantly, while miR-223-3p levels increased markedly in peri-lesion tissues after TBI. The overexpression of Armcx1 significantly reduced TBI-induced neurological dysfunction, neuronal cell death, mitochondrial dysfunction, and axonal injury, while the knockdown of Armcx1 had the opposite effect. Armcx1 was potentially a direct target of miR-223-3p. The miR-223-3p mimic obviously reduced the Armcx1 protein level, while the miR-223-3p inhibitor had the opposite effect. Finally, the miR-223-3p inhibitor dramatically improved mitochondrial membrane potential (MMP) and increased the total length of the neurites without affecting branching numbers. In summary, our results suggest that the decreased expression of Armcx1 protein in neurons after experimental TBI aggravates secondary brain injury, which may be regulated by miR-223-3p. Therefore, this study provides a potential therapeutic approach for treating TBI.

Traumatic brain injury and immunological outcomes: the double-edged killer

Traumatic brain injury (TBI) is a significant cause of mortality and morbidity worldwide resulting from falls, car accidents, sports, and blast injuries. TBI is characterized by severe, life-threatening consequences due to neuroinflammation in the brain. Contact and collision sports lead to higher disability and death rates among young adults. Unfortunately, no therapy or drug protocol currently addresses the complex pathophysiology of TBI, leading to the long-term chronic neuroinflammatory assaults. However, the immune response plays a crucial role in tissue-level injury repair. This review aims to provide a better understanding of TBI's immunobiology and management protocols from an immunopathological perspective. It further elaborates on the risk factors, disease outcomes, and preclinical studies to design precisely targeted interventions for enhancing TBI outcomes.

Models of traumatic brain injury-highlights and drawbacks

Traumatic brain injury (TBI) is the leading cause for high morbidity and mortality rates in young adults, survivors may suffer from long-term physical, cognitive, and/or psychological disorders. Establishing better models of TBI would further our understanding of the pathophysiology of TBI and develop new potential treatments. A multitude of animal TBI models have been used to replicate the various aspects of human TBI. Although numerous experimental neuroprotective strategies were identified to be effective in animal models, a majority of strategies have failed in phase II or phase III clinical trials. This failure in clinical translation highlights the necessity of revisiting the current status of animal models of TBI and therapeutic strategies. In this review, we elucidate approaches for the generation of animal models and cell models of TBI and summarize their strengths and limitations with the aim of exploring clinically meaningful neuroprotective strategies.

HDAC3 inhibitor (BRD3308) modulates microglial pyroptosis and neuroinflammation through PPARγ/NLRP3/GSDMD to improve neurological function after intraventricular hemorrhage in mice

Neuroinflammation plays a vital role in intraventricular hemorrhage (IVH). Excessive neuroinflammation after IVH can activate the inflammasome in the cell and accelerate the occurrence of pyroptosis in cells, produce more inflammatory mediators, increase cell death, and lead to neurological deficits. Previous studies have reported that BRD3308 (BRD), an inhibitor of histone deacetylation by histone deacetylase 3 (HDAC3), suppresses inflammation-induced apoptosis and exhibits anti-inflammatory properties. However, it is unclear how BRD reduces the occurrence of the inflammatory cascade. In this study, we stereotactically punctured the ventricles of male C57BL/6J mice and injected autologous blood via the tail vein to simulate ventricular hemorrhage. Magnetic resonance imaging was used to detect ventricular hemorrhage and enlargement. Our findings demonstrated that BRD treatment significantly improved neurobehavioral performance and decreased neuronal loss, microglial activation, and pyroptosis in the hippocampus after IVH. At the molecular level, this treatment upregulated the expression of peroxisome proliferator-activated receptor γ (PPARγ) and inhibited NLRP3-mediated pyroptosis and inflammatory cytokines. Therefore, we concluded that BRD reduced pyroptosis and neuroinflammation and improve nerve function in part by activating the PPARγ/NLRP3/GSDMD signaling pathway. Our findings suggest a potential preventive role for BRD in IVH.

Induction Mechanism of Ferroptosis, Necroptosis, and Pyroptosis: A Novel Therapeutic Target in Nervous System Diseases

In recent years, three emerging cell deaths, ferroptosis, necroptosis and pyroptosis, have gradually attracted everyone's attention, and they also play an important role in the occurrence and development of various diseases. Ferroptosis is an idiographic iron-dependent form regulated cell death with the hallmark of accumulation of the intracellular reactive oxygen species (ROS). Necroptosis is a form of regulated necrotic cell death mediated by the receptor-interacting protein kinase 1(RIPK1) and receptor-interacting protein kinase 3RIPK3. Pyroptosis, also known as cell inflammatory necrosis, is a programmed cell necrosis mediated by Gasdermin D (GSDMD). It is manifested by the continuous swelling of the cells until the cell membrane ruptures, resulting in the release of the cell contents and the activation of a strong inflammatory response. Neurological disorders remain a clinical challenge and patients do not respond well to conventional treatments. Nerve cell death can aggravate the occurrence and development of neurological diseases. This article reviews the specific mechanisms of these three types of cell death and their relationship with neurological diseases and the evidence for the role of the three types of cell death in neurological diseases; understanding these pathways and their mechanisms is helpful for the treatment of neurological diseases.

Melatonin modulates the aggravation of pyroptosis, necroptosis, and neuroinflammation following cerebral ischemia and reperfusion injury in obese rats

Obesity is well-established as a common comorbidity in ischemic stroke. The increasing evidence has revealed that it also associates with the exacerbation of brain pathologies, resulting in increasingly severe neurological outcomes following cerebral ischemia and reperfusion (I/R) damage. Mechanistically, pyroptosis and necroptosis are novel forms of regulated death that relate to the propagation of inflammatory signals in case of cerebral I/R. Previous studies noted that pyroptotic and necroptotic signaling were exacerbated in I/R brain of obese animals and led to the promotion of brain tissue injury. This study aimed to investigate the roles of melatonin on pyroptosis, necroptosis, and pro-inflammatory pathways occurring in the I/R brain of obese rats. Male Wistar rats were given a high-fat diet for 16 weeks to induce the obese condition, and then were divided into 4 groups: Sham-operated, I/R treated with vehicle, I/R treated with melatonin (10 mg/kg), and I/R treated with glycyrrhizic acid (10 mg/kg). All drugs were administered via intraperitoneal injection at the onset of reperfusion. The development of neurological deficits, cerebral infarction, histological changes, neuronal death, and glial cell hyperactivation were investigated. This study revealed that melatonin effectively improved these detrimental parameters. Furthermore, the processes of pyroptosis, necroptosis, and inflammation were all diminished by melatonin treatment. A summary of the findings is that melatonin effectively reduces ischemic brain pathology and thereby improves post-stroke outcomes in obese rats by modulating pyroptosis, necroptosis, and inflammation.

Circulating extracellular vesicles from patients with traumatic brain injury induce cerebrovascular endothelial dysfunction

Endothelial dysfunction is a key proponent of pathophysiological process of traumatic brain injury (TBI). We previously demonstrated that extracellular vesicles (EVs) released from injured brains led to endothelial barrier disruption and vascular leakage. However, the molecular mechanisms of this EV-induced endothelial dysfunction (endotheliopathy) remain unclear. Here, we enriched plasma EVs from TBI patients (TEVs), and detected high mobility group box 1 (HMGB1) exposure to 50.33 ± 10.17% of TEVs and the number of HMGB1⁺TEVs correlated with injury severity. We then investigated for the first time the impact of TEVs on endothelial function using adoptive transfer models. We found that TEVs induced dysfunction of cultured human umbilical vein endothelial cells and mediated endothelial dysfunction in both normal and TBI mice, which were propagated through the HMGB1-activated receptor for advanced glycation end products (RAGE)/Cathepsin B signaling, and the resultant NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation and canonical caspase-1/gasdermin D (GSDMD)-dependent pyroptosis. Finally, von Willebrand factor (VWF) was detected on the surface of 77.01 ± 7.51% of HMGB1⁺TEVs. The TEV-mediated endotheliopathy was reversed by a polyclonal VWF antibody, indicating that VWF might serve a coupling factor that tethered TEVs to ECs, thus facilitating HMGB1-induced endotheliopathy. These results suggest that circulating EVs isolated from patients with TBI alone are sufficient to induce endothelial dysfunction and contribute to secondary brain injury that are dependent on immunologically active HMGB1 exposed on their surface. This finding provided new insight for the development of potential therapeutic targets and diagnostic biomarkers for TBI.

LDC7559 inhibits microglial activation and GSDMD-dependent pyroptosis after subarachnoid hemorrhage

Mounting evidence indicates that inhibition of microglial activation and neuronal pyroptosis plays important roles in brain function recovery after subarachnoid hemorrhage (SAH). LDC7559 is a newly discovered gasdermin D (GSDMD) inhibitor. Previous studies have demonstrated that LDC7559 could inhibit microglial proliferation and pyroptosis. However, the beneficial effects of LDC7559 on SAH remain obscure. Based on this background, we investigated the potential role and the mechanism of LDC7559 on SAH-induced brain damage both in vivo and in vitro. The findings revealed that microglial activation and neuronal pyroptosis were evidently increased after SAH, which could be markedly suppressed by LDC7559 both in vivo and in vitro. Meanwhile, LDC7559 treatment reduced neuronal apoptosis and improved behavior function. Mechanistically, LDC7559 decreased the levels of GSDMD and cleaved GSDMD after SAH. In contrast, nod-like receptor pyrin domain-containing 3 (NLRP3) inflammasome activation by nigericin increased GSDMD-mediated pyroptosis and abated the beneficial effects of LDC7559 on SAH-induced brain damage. However, LDC7559 treatment did not significantly affect the expression of NLRP3 after SAH. Taken together, LDC7559 might suppress neuronal pyroptosis and microglial activation after SAH by inhibiting GSDMD, thereby promoting brain functional recovery.

GSDMD knockdown exacerbates hippocampal damage and seizure susceptibility by crosstalk between pyroptosis and apoptosis in kainic acid-induced temporal lobe epilepsy

BACKGROUND

Neuronal loss is a vital pathological feature of temporal lobe epilepsy (TLE). However, the exact mechanism of neuronal loss in TLE is not fully understood. Pyroptosis, a novel form of programmed cell death (PCD), has been considered a contributor to the pathogenesis of TLE. However, recent studies have implicated extensive molecular crosstalk among pyroptosis, apoptosis, and necroptosis in various diseases, and they can be transformed to each other according to different contexts. This study aimed to investigate whether gasdermin D (GSDMD)-mediated pyroptosis is involved in the pathogenesis of TLE and whether crosstalk exists in the process of the modulation of pyroptosis.

METHODS

The TLE model was established by intra-amygdala injection of kainic acid. The Racine score and local field potential (LFP) recordings were used to assess seizure severity. Western blotting and immunofluorescence were applied to detect the levels and cellular localization of GSDMD. The neuronal loss and type of neuronal death in the bilateral hippocampus were assessed by Nissl staining and flow cytometry analysis. The underlying crosstalk among pyroptosis, apoptosis, and necroptosis was explored by western blot and verified by VX765.

RESULTS

GSDMD was significantly upregulated and mainly expressed within the neurons of the hippocampus in the TLE model. Inhibition of pyroptosis by GSDMD knockdown triggered caspase-3-mediated apoptosis, leading to excess neuronal loss and deterioration of epileptic behaviors. Blocking caspase-1 markedly inhibited caspase-3-mediated apoptosis and improved epileptic behaviors under GSDMD knockdown.

CONCLUSIONS

Our results demonstrate that GSDMD-mediated pyroptosis is involved in the pathogenesis of TLE. However, inhibition of GSDMD triggers caspase-1-mediated crosstalk between pyroptosis and apoptosis, which exacerbates neuronal loss and seizure susceptibility. Therefore, the complex crosstalk among different forms of PCD should be considered when a potential molecular target in the single PCD pathway is modulated. On the other hand, along with further studies of molecular crosstalk among the PCD pathways, taking advantage of crosstalk to attenuate neuronal loss may provide new insight for the clinical therapy of TLE.

Hyperactivation of TRPV4 causes the hippocampal pyroptosis pathway and results in cognitive impairment in LPS-treated mice

Pyroptosis, a newly discovered proinflammatory programmed cell death, is involved in the regulation of cognitive dysfunction, such as Alzheimer's disease. Exploring potential drug targets that prevent pyroptotic procedures might benefit the development of a cure for these diseases. In the present study, we explored whether the transient receptor potential vanilloid 4 (TRPV4) blocker HC067047 and knockdown of TRPV4 in the hippocampus could improve cognitive behavior through the inhibition of pyroptosis in a mouse model developed using systemic administration of lipopolysaccharide (LPS). We found that systemic administration of HC067047 or knockdown of hippocampal TRPV4 prevented the activation of canonical and noncanonical pyroptosis in the hippocampus of LPS-treated mice. Consistent with the inhibition of the hippocampal pyroptosis pathway, a knockdown of hippocampal TRPV4 lowered expression of TNF-α, IL-1β, IL-18, and IL-6. Furthermore, we verified that the main pyroptosis cell type might be a neuron, indicated by reduced neuronal marker expression. Mechanically, we also found that knockdown of hippocampal TRPV4 might inhibit phosphorylation of CamkⅡα which results in NFκb mediated inflammasome reduction in the hippocampus of LPS-treated mice. More interestingly, mice intraperitoneally injected with HC067047 or the hippocampus injected with TRPV4 shRNA showed improved cognitive behavior, as indicated by the enhanced discrimination ratio in the NORT, NOPT, and SNPT. Collectively, we consider that HC067047 might be a small molecular drug that prevents pyroptosis, and TRPV4 could be an effective therapeutic target for preventing pyroptosis-induced cognitive dysfunction.

Inflammasomes as biomarkers and therapeutic targets in traumatic brain injury and related-neurodegenerative diseases: A comprehensive overview

Given the ambiguity surrounding traumatic brain injury (TBI) pathophysiology and the lack of any Food and Drug Administration (FDA)-approved neurotherapeutic drugs, there is an increasing need to better understand the mechanisms of TBI. Recently, the roles of inflammasomes have been highlighted as both potential therapeutic targets and diagnostic markers in different neurodegenerative disorders. Indeed, inflammasome activation plays a pivotal function in the central nervous system (CNS) response to many neurological conditions, as well as to several neurodegenerative disorders, specifically, TBI. This comprehensive review summarizes and critically discusses the mechanisms that govern the activation and assembly of inflammasome complexes and the major methods used to study inflammasome activation in TBI and its implication for other neurodegenerative disorders. Also, we will review how inflammasome activation is critical in CNS homeostasis and pathogenesis, and how it can impact chronic TBI sequalae and increase the risk of developing neurodegenerative diseases. Additionally, we discuss the recent updates on inflammasome-related biomarkers and the potential to utilize inflammasomes as putative therapeutic targets that hold the potential to better diagnose and treat subjects with TBI.

EGCG promotes the sensory function recovery in rats after dorsal root crush injury by upregulating KAT6A and inhibiting pyroptosis

Dorsal root injury usually leads to irreversible sensory function loss and lacks effective treatments. (-)-epigallocatechin-3-gallate (EGCG) is reported to exert neuroprotective roles in the nervous systems. However, the function of EGCG in treating dorsal root injury remains unclear. Hence, we built the dorsal root crush injury (DRCI) rat model to be treated with EGCG, followed by the western blot, Enzyme-linked immunosorbent assay, and sensory behavior tests. We observed that EGCG can upregulate the Lysine acetyltransferase 6A (KAT6A) level and inhibit the pyroptosis, indicated by downregulated gasdermin-D, caspase-1, and interleukin 18 protein levels, and alleviate the neuropathic pain, indicated by the decreased paw withdraw threshold in Plantar test and decreased paw withdraw latency in von Frey test, and downregulated calcitonin gene-related peptide, nerve growth factor, and c-Fos protein levels. But EGCG cannot alleviate the neuropathic pain when the KAT6A was inhibited by CTX-0124143 and pyroptosis was activated by Miltirone. These combined results indicated that EGCG can promote the sensory function recovery in rats after DRCI via upregulating KAT6A and inhibiting pyroptosis, laying the foundation for EGCG to be a novel candidate for the treatment of dorsal root injury.

Knockout of Sirt2 alleviates traumatic brain injury in mice

Sirtuin 2 (SIRT2) inhibition or Sirt2 knockout in animal models protects against the development of neurodegenerative diseases and cerebral ischemia. However, the role of SIRT2 in traumatic brain injury (TBI) remains unclear. In this study, we found that knockout of Sirt2 in a mouse model of TBI reduced brain edema, attenuated disruption of the blood-brain barrier, decreased expression of the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome, reduced the activity of the effector caspase-1, reduced neuroinflammation and neuronal pyroptosis, and improved neurological function. Knockout of Sirt2 in a mechanical stretch injury cell model in vitro also decreased expression of the NLRP3 inflammasome and pyroptosis. Our findings suggest that knockout of Sirt2 is neuroprotective against TBI; therefore, Sirt2 could be a novel target for TBI treatment.

Inhibition of neutrophil extracellular trap formation attenuates NLRP1-dependent neuronal pyroptosis via STING/IRE1α pathway after traumatic brain injury in mice

Introduction

Increased neutrophil extracellular trap (NET) formation has been reported to be associated with cerebrovascular dysfunction and neurological deficits in traumatic brain injury (TBI). However, the biological function and underlying mechanisms of NETs in TBI-induced neuronal cell death are not yet fully understood.

Methods

First, brain tissue and peripheral blood samples of TBI patients were collected, and NETs infiltration in TBI patients was detected by immunofluorescence staining and Western blot. Then, a controlled cortical impact device was used to model brain trauma in mice, and Anti-Ly6G, DNase, and CL-amidine were given to reduce the formation of neutrophilic or NETs in TBI mice to evaluate neuronal death and neurological function. Finally, the pathway changes of neuronal pyroptosis induced by NETs after TBI were investigated by administration of peptidylarginine deiminase 4 (a key enzyme of NET formation) adenovirus and inositol-requiring enzyme-1 alpha (IRE1α) inhibitors in TBI mice.

Results

We detected that both peripheral circulating biomarkers of NETs and local NETs infiltration in the brain tissue were significantly increased and had positive correlations with worse intracranial pressure (ICP) and neurological dysfunction in TBI patients. Furthermore, the depletion of neutrophils effectively reduced the formation of NET in mice subjected to TBI. we found that degradation of NETs or inhibition of NET formation significantly inhibited nucleotide-binding oligomerization domain (NOD)-like receptor pyrin domain containing 1 (NLRP1) inflammasome-mediated neuronal pyroptosis after TBI, whereas these inhibitory effects were abolished by cyclic GMP-AMP (cGAMP), an activator of stimulating Interferon genes (STING). Moreover, overexpression of PAD4 in the cortex by adenoviruses could aggravate NLRP1-mediated neuronal pyroptosis and neurological deficits after TBI, whereas these pro-pyroptotic effects were rescued in mice also receiving STING antagonists. Finally, IRE1α activation was significantly upregulated after TBI, and NET formation or STING activation was found to promote this process. Notably, IRE1α inhibitor administration significantly abrogated NETs-induced NLRP1 inflammasome-mediated neuronal pyroptosis in TBI mice.

Discussion

Our findings indicated that NETs could contribute to TBI-induced neurological deficits and neuronal death by promoting NLRP1-mediated neuronal pyroptosis. Suppression of the STING/ IRE1α signaling pathway can ameliorate NETs-induced neuronal pyroptotic death after TBI.

Dopamine inhibits pyroptosis and attenuates secondary damage after spinal cord injury in female mice

BACKGROUND

An excessive inflammatory response accompanies the pathogenesis of spinal cord injury (SCI) and has been found to be promoted by inflammasomes in a variety of disease models. Dopamine is a neurotransmitter that also regulates nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasome-dependent neuroinflammation. However, little is known regarding the effects and molecular mechanisms underlying the role of dopamine in SCI.

METHODS

Functional recovery in mice was assessed with the Basso Mouse Scale (BMS). Neuronal loss was evaluated with immunochemical staining of NeuN. Pyroptosis was assessed with immunofluorescence staining, flow cytometry, western blotting, and cell viability and cytotoxicity assays.

RESULTS

Dopamine was significantly associated with enhanced locomotor recovery after SCI, and with decreased NLRP3 inflammasome activation, pyroptosis, neuronal loss and pro-inflammatory cytokine levels. In vitro data suggested that dopamine suppressed NLRP3 inflammasome activation and pyroptosis, and decreased pro-inflammatory cytokine levels.

CONCLUSIONS

Dopamine may be a novel approach for alleviating secondary damage after SCI.

Surface-fill H2S-releasing silk fibroin hydrogel for brain repair through the repression of neuronal pyroptosis

Traumatic brain injury (TBI) remains the major cause of disability and mortality worldwide due to the persistent neuroinflammation and neuronal death induced by TBI. Among them, pyroptosis, a specific type of programmed cell death (PCD) triggered by inflammatory signals, plays a significant part in the pathological process after TBI. Inhibition of neuroinflammation and pyroptosis is considered a possible strategy for the treatment of TBI. In our previous study, exogenous hydrogen sulfide(H₂S) exerted a neuroprotective effect after TBI. Here, we developed a surface-fill H₂S-releasing silk fibroin (SF) hydrogel (H₂S@SF hydrogel) to achieve small-dose local administration and avoid volatile and toxic side effects. We used a controlled cortical impact (CCI) to establish a mild TBI model in mice to examine the effect of H₂S@SF hydrogel on TBI-induced pyroptosis. We found that H₂S@SF hydrogel inhibited the expression of H₂S synthase in neurons after TBI and significantly inhibited TBI-induced neuronal pyroptosis. In addition, immunofluorescence staining results showed that the necroptosis protein receptor-interacting serine/threonine-protein kinase 1 (RIPK1) partially colocalized with the pyroptosis protein Gasdermin D (GSDMD) in the same cells. H₂S@SF hydrogel can also inhibit the expression of the necroptosis protein. Moreover, H₂S@SF hydrogel also alleviates brain edema and the degree of neurodegeneration in the acute phase of TBI. The neuroprotective effect of H₂S@SF hydrogel was further confirmed by wire-grip test, open field test, Morris water maze, beam balance test, radial arm maze, tail suspension, and forced swimming test. Lastly, we also measured spared tissue volume, reactive astrocytes and activated microglia to demonstrate H₂S@SF hydrogel impacts on long-term prognosis in TBI. Our study provides a new theoretical basis for the treatment of H₂S after TBI and the clinical application of H₂S@SF hydrogel. STATEMENT OF SIGNIFICANCE: Silk fibroin (SF) hydrogel controls the release of hydrogen sulfide (H₂S) to inhibit neuronal pyroptosis and neuroinflammation in injured brain tissue. In this study, we synthesized a surface-fill H₂S-releasing silk fibroin hydrogel, which could slowly release H₂S to reshape the homeostasis of endogenous H₂S in injured neurons and inhibit neuronal pyroptosis in a mouse model of traumatic brain injury. Meanwhile, H₂S@SF hydrogel could alleviate brain edema and the degree of neurodegeneration, improve motor dysfunction, anxious behavior and memory impairment caused by TBI, reduce tissue loss and ameliorate neuroinflammation. Our study provides a new theoretical basis for the treatment of H₂S after TBI and the clinical application of H₂S@SF hydrogel.

Honokiol Reduces Mitochondrial Dysfunction and Inhibits Apoptosis of Nerve Cells in Rats with Traumatic Brain Injury by Activating the Mitochondrial Unfolded Protein Response

This study was designed to determine the effects and underlying mechanism of honokiol (HNK) on traumatic brain injury (TBI). A rat TBI model was constructed using the modified Feeney free-fall percussion method and treatment with HNK via intraperitoneal injection. The brain tissues of the rats in each group were assessed using the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay to detect the level of neuronal apoptosis. Western blots were used to detect the expression levels of apoptosis-related proteins (Bcl-2 and Bax), and ELISAs were used to measure the levels of pro-inflammatory cytokines (IL-18 and IL-1β) and the activity of caspase-1. In addition, the mitochondrial membrane potential, reactive oxygen species (ROS), and adenosine 5'-triphosphate (ATP) were also measured. Western blots and qRT-PCRs were used to determine the relative expression levels of the mitochondrial unfolded protein response (UPRmt)-related proteins and mRNAs. Based on the experimental results, treatment with HNK was associated with a decrease in the number of TUNEL-positive cells, downregulated Bax expression levels, elevated Bcl-2 expression levels, and inhibition of neuronal apoptosis in the brain tissue of TBI rats. HNK also suppressed neuroinflammation by decreasing IL-1β and IL-18 levels and caspase-1 activity. Additionally, HNK lowered the mitochondrial membrane potential and ROS levels, increased ATP levels, and improved mitochondrial dysfunction in neural cells. Furthermore, in the investigation of the mechanism of HNK on TBI, we observed that HNK could activate UPRmt by upregulating the mRNA and protein expression levels of HSPA9, CLPP, and HSP60 in the brain tissues of TBI rats. Collectively, HNK reduced mitochondrial dysfunction, inhibited the apoptosis of nerve cells, and attenuated inflammation in the brains of TBI rats. The protective effect of HNK may be achieved through the activation of UPRmt.

Ligustroflavone exerts neuroprotective activity through suppression of NLRP1 inflammasome in ischaemic stroke mice

Inflammation is thought to play an important role in the pathophysiology of ischaemic stroke, which is a main cause of disability and morbidity worldwide. Inhibition of the NOD-like receptor protein 1 (NLRP1) inflammasome has been reported to alleviate the inflammatory response in cell and animal models. Ligustroflavone (LIG) is a compound derived from Ligustrum lucidum, which shows anti-inflammatory activity and may play a beneficial role in a number of neurological diseases. To date, the potential for LIG to act through NLRP1 as a treatment for ischemic stroke has not been studied. The present study established an ischaemic stroke model by middle cerebral artery occlusion (MCAO). Modified neurological severity scoring, open-field and the Rotarod test were used to assess neurological deficits. Staining with Hoechst 33258 and western blotting were used to evaluate neuronal damage. Expression levels of NLRP1 inflammasome complexes and inflammatory cytokines were determined using western blotting, enzyme-linked immunosorbent assay and reverse transcription-quantitative PCR. Treatment with LIG minimized the impairment of neurological function and blocked neuronal damage in MCAO mice. In addition, treatment with LIG attenuated the upregulation of expression levels of the NLRP1 inflammasome complexes and the inflammatory cytokines TNF-α, IL-18, IL-6 and IL-1β. Overall, LIG played an important role in anti-inflammatory and neuroprotective activity in MCAO models of ischaemic stroke.

Platelet derived growth factor promotes the recovery of traumatic brain injury by inhibiting endoplasmic reticulum stress and autophagy-mediated pyroptosis

Autophagy and endoplasmic reticulum stress (ER stress) are important in numerous pathological processes in traumatic brain injury (TBI). Growing evidence has indicated that pyroptosis-associated inflammasome is involved in the pathogenesis of TBI. Platelet derived growth factor (PDGF) has been reported to be as a potential therapeutic drug for neurological diseases. However, the roles of PDGF, autophagy and ER stress in pyroptosis have not been elucidated in the TBI. This study investigated the roles of ER stress and autophagy after TBI at different time points. We found that the ER stress and autophagy after TBI were inhibited, and the expressions of pyroptosis-related proteins induced by TBI, including NLRP3, Pro-Caspase1, Caspase1, GSDMD, GSDMD P30, and IL-18, were decreased upon PDGF treatment. Moreover, the rapamycin (RAPA, an autophagy activator) and tunicamycin (TM, an ER stress activator) eliminated the PDGF effect on the pyroptosis after TBI. Interestingly, the sodium 4-phenylbutyrate (4-PBA, an ER stress inhibitor) suppressed autophagy but 3-methyladenine (3-MA, an autophagy inhibitor) not for ER stress. The results revealed that PDGF improved the functional recovery after TBI, and the effects were markedly reversed by TM and RAPA. Taken together, this study provides a new insight that PDGF is a potential therapeutic strategy for enhancing the recovery of TBI.

The role of regulatory necrosis in traumatic brain injury

Traumatic brain injury (TBI) is a major cause of death and disability in the population worldwide, of which key injury mechanism involving the death of nerve cells. Many recent studies have shown that regulatory necrosis is involved in the pathological process of TBI which includes necroptosis, pyroptosis, ferroptosis, parthanatos, and Cyclophilin D (CypD) mediated necrosis. Therefore, targeting the signaling pathways involved in regulatory necrosis may be an effective strategy to reduce the secondary injury after TBI. Meanwhile, drugs or genes are used as interference factors in various types of regulatory necrosis, so as to explore the potential treatment methods for the secondary injury after TBI. This review summarizes the current progress on regulatory necrosis in TBI.

JQ1 attenuates neuroinflammation by inhibiting the inflammasome-dependent canonical pyroptosis pathway in SAE

Sepsis-associated encephalopathy (SAE) manifests clinically in hyperneuroinflammation. Pyroptosis, which can induce an inflammatory cascade response, has been considered to be a causative factor of SAE. Evidence has shown that the bromo- and extraterminal (BET) proteins (including BRD2, BRD3, BRD4 and BRDT) inhibitor JQ1 can inhibit inflammation and suppress pyroptosis in various diseases. Therefore, we examined the effect of JQ1 on inflammasome-induced pyroptosis in the hippocampus in a mouse model of sepsis induced by lipopolysaccharide (LPS) injection. The results showed that JQ1 treatment alleviated sepsis-related symptoms, protected the blood-brain barrier (BBB), as indicated by upregulated expression of the tight junction proteins occludin and ZO-1, and remarkably rescued neuronal damage in SAE mice. Mechanistically, we demonstrated that JQ1 intervention inhibited the expression of BRD proteins and decreased the expression of inflammasomes by blocking phospho-nuclear factor kappa B (p-NF-κB) signalling, attenuating the canonical pyroptosis (mediated by cleaved-Caspase1/11) pathway and the release of proinflammatory factors in the hippocampus of septic mice. Interestingly, we also found that JQ1 selectively suppressed the activation of hippocampal microglia in SAE mice. Thus, JQ1 protected the hippocampal BBB and neuronal damage through the attenuation of neuroinflammation by inhibiting the inflammasome-dependent canonical pyroptosis pathway induced by LPS injection in mice, and JQ1 may be a promising target for the prevention of SAE.

Anti-Inflammation and Anti-Pyroptosis Activities of Mangiferin via Suppressing NF-κB/NLRP3/GSDMD Signaling Cascades

Mangiferin (MF), a xanthone that extensively exists in many herbal medicines, processes significant activities of anti-inflammation and immunomodulation. The potential regulatory effect and mechanism of mangiferin on cell pyroptosis remain unclear. In this study, mouse bone-marrow-derived macrophages (BMDMs) were stimulated with 1 μg/mL LPS to induce cell pyroptosis and were treated with 10, 50, or 100 μg/mL MF for regulating pyroptosis. The cell supernatants TNF-α, IL-1β, IL-6, and IL-18 were detected by enzyme-linked immunosorbent assay (ELISA); gene expression of TNF-α, IL-1β, IL-6, IL-18, Caspase-1, Caspase-11, and gasdermin D (GSDMD) was tested by real-time polymerase chain reaction (RT-PCR), and protein expression levels of apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC), nod-like receptor protein-3 (NLRP3), caspase-1, caspase-11, GSDMD, and NF-κB were detected by Western blot. The results showed that MF significantly inhibited the secretion and gene expression of TNF-α, IL-6, IL-1β, and IL-18 that were elevated by LPS. Moreover, MF significantly suppressed the gene expression of Caspase-1, Caspase-11, and GSDMD, and decreased the protein levels of NLRP3, caspase-1, caspase-11, full-length GSDMD (GSDMD-FL), GSDMD N-terminal (GSDMD-N), and NF-κB. In conclusion, mangiferin has a multi-target regulating effect on inflammation and pyroptosis by inhibiting the NF-κB pathway, suppressing inflammatory caspase-mediated pyroptosis cascades, and reducing GSDMD cleavage in LPS-induced BMDMs.

Artemisinin analog SM934 alleviates epithelial barrier dysfunction via inhibiting apoptosis and caspase-1-mediated pyroptosis in experimental colitis

Intestinal barrier disruption due to the intestinal epithelial cells’ (IECs) death is one of the critical pathological features of inflammatory bowel diseases (IBDs). SM934, an artemisinin analog, has previously been proven to ameliorate colitis induced by dextran sulfate sodium (DSS) in mice by suppressing inflammation response. In this study, we investigated the protective effects of SM934 on the epithelial barrier and the underlying mechanism in trinitrobenzene sulfonic acid (TNBS)-induced colitis mice. We demonstrated that SM934 restored the body weight and colon length, and improved the intestine pathology. Furthermore, SM934 treatment preserved the intestinal barrier function via decreasing the intestinal permeability, maintaining epithelial tight junction (TJ) protein expressions, and preventing apoptosis of epithelial cells, which were observed both in the colon tissue and the tumor necrosis factor-α (TNF-α)-induced human colonic epithelial cell line HT-29. Specifically, SM934 reduced the pyroptosis of IECs exposed to pathogenic signaling and inhibited pyroptosis-related factors such as NOD-like receptor family pyrin domain containing 3 (NLRP3), adapter apoptosis-associated speck-like protein (ASC), cysteine protease-1 (caspase-1), gasdermin (GSDMD), interleukin-18 (IL-18), and high-mobility group box 1 (HMGB1) both in colon tissue and lipopolysaccharide (LPS) and adenosine triphosphate (ATP) co-stimulated HT-29 cells in vitro. Moreover, SM934 interdicted pyroptosis via blocking the transduction of mitogen-activated protein kinase (MAPK) and nuclear factor-kB (NF-kB) signaling pathways. In conclusion, SM934 protected TNBS-induced colitis against intestinal barrier disruption by inhibiting the apoptosis and pyroptosis of epithelial cells via the NLRP3/NF-κB/MAPK signal axis, and intestinal barrier protection in company with an anti-inflammatory strategy might yield greater benefits in IBD treatment.

Mesenchymal stem cells protect against TBI-induced pyroptosis in vivo and in vitro through TSG-6

Background

Pyroptosis, especially microglial pyroptosis, may play an important role in central nervous system pathologies, including traumatic brain injury (TBI). Transplantation of mesenchymal stem cells (MSCs), such as human umbilical cord MSCs (hUMSCs), has been a focus of brain injury treatment. Recently, MSCs have been found to play a role in many diseases by regulating the pyroptosis pathway. However, the effect of MSC transplantation on pyroptosis following TBI remains unknown. Tumor necrosis factor α stimulated gene 6/protein (TSG-6), a potent anti-inflammatory factor expressed in many cell types including MSCs, plays an anti-inflammatory role in many diseases; however, the effect of TSG-6 secreted by MSCs on pyroptosis remains unclear.

Methods

Mice were subjected to controlled cortical impact injury in vivo. To assess the time course of pyroptosis after TBI, brains of TBI mice were collected at different time points. To study the effect of TSG-6 secreted by hUMSCs in regulating pyroptosis, normal hUMSCs, sh-TSG-6 hUMSCs, or different concentrations of rmTSG-6 were injected intracerebroventricularly into mice 4 h after TBI. Neurological deficits, double immunofluorescence staining, presence of inflammatory factors, cell apoptosis, and pyroptosis were assessed. In vitro, we investigated the anti-pyroptosis effects of hUMSCs and TSG-6 in a lipopolysaccharide/ATP-induced BV2 microglial pyroptosis model.

Results

In TBI mice, the co-localization of Iba-1 (marking microglia/macrophages) with NLRP3/Caspase-1 p20/GSDMD was distinctly observed at 48 h. In vivo, hUMSC transplantation or treatment with rmTSG-6 in TBI mice significantly improved neurological deficits, reduced inflammatory cytokine expression, and inhibited both NLRP3/Caspase-1 p20/GSDMD expression and microglial pyroptosis in the cerebral cortices of TBI mice. However, the therapeutic effect of hUMSCs on TBI mice was reduced by the inhibition of TSG-6 expression in hUMSCs. In vitro, lipopolysaccharide/ATP-induced BV2 microglial pyroptosis was inhibited by co-culture with hUMSCs or with rmTSG-6. However, the inhibitory effect of hUMSCs on BV2 microglial pyroptosis was significantly reduced by TSG-6-shRNA transfection.

Conclusion

In TBI mice, microglial pyroptosis was observed. Both in vivo and in vitro, hUMSCs inhibited pyroptosis, particularly microglial pyroptosis, by regulating the NLRP3/Caspase-1/GSDMD signaling pathway via TSG-6.

LDC7559 Exerts Neuroprotective Effects by Inhibiting GSDMD-dependent Pyroptosis of Microglia in Mice with Traumatic Brain Injury

Pyroptosis is considered one of a critical factor in the recovery of neurological function following traumatic brain injury. Brain injury activates a molecular signaling cascade associated with pyroptosis and inflammation, including NLRP3, inflammatory cytokines, caspase-1, gasdermin D (GSDMD), and other pyroptosis-related proteins. In this study, we explored the neuroprotective effects of LDC7559, a GSDMD inhibitor. Briefly, LDC7559, siRNA-GSDMD (si-GSDMD), or equal solvent was administrated to mice with a lipopolysaccharide + nigericin (LPS + Nig) model in vitro or with controlled cortical impact brain injury. The findings revealed that inflammation and pyroptosis levels were decreased by LDC7559 or si-GSDMD treatment both in vitro and in vivo. Immunofluorescence staining, brain water content, hematoxylin and eosin staining, and behavioral investigations suggested that LDC7559 or si-GSDMD inhibited microglial proliferation, ameliorated cerebral edema, reduced brain tissue loss, and promoted brain function recovery. Taken together, LDC7559 may inhibit pyroptosis and reduce inflammation by inhibiting GSDMD, thereby promoting the recovery of neurological function.

STING mediates neuroinflammatory response by activating NLRP3-related pyroptosis in severe traumatic brain injury

Long-term neurological deficits after severe traumatic brain injury (TBI), including cognitive dysfunction and emotional impairments, can significantly impair rehabilitation. Glial activation induced by inflammatory response is involved in the neurological deficits post-TBI. This study aimed to investigate the role of the stimulator of interferon genes (STING)-nucleotide-binding oligomerization domain-like receptor pyrin domain-containing-3 (NLRP3) signaling in a rodent model of severe TBI. Severe TBI models were established using weight-drop plus blood loss-reinfusion. Selective STING agonist ADU-S100 or antagonist C-176 was given as a single dose after modeling. Further, NLRP3 inhibitor MCC950 or activator nigericin, or caspase-1 inhibitor VX765, was given as an intracerebroventricular injection 30 min before modeling. After that, a novel object recognition test, open field test, force swimming test, western blot, and immunofluorescence assays were used to assess behavioral and pathological changes in severe TBI. Administration of C-176 alleviated TBI-induced cognitive dysfunction and emotional impairments, neuronal loss, and inflammatory activation of glia cells. However, the administration of STING agonist ADU-S100 exacerbated TBI-induced behavioral and pathological changes. In addition, STING activation exacerbated pyroptosis-associated neuroinflammation via promoting glial activation, as evidenced by increased cleaved caspase-1 and GSDMD N-terminal expression. In contrast, the administration of C-176 showed anti-pyroptotic effects. The neuroprotective effects of C-176 were partially reversed by the NLRP3 activator, nigericin. Collectively, glial STING is responsible for neuroinflammation post-TBI. However, pharmacologic inhibition of STING led to a remarkable improvement of neuroinflammation partly through suppressing NLRP3 signaling. The STING-NLRP3 signaling is a potential therapeutic target in TBI-induced neurological dysfunction.

Microglia Pyroptosis: A Candidate Target for Neurological Diseases Treatment

In addition to its profound implications in the fight against cancer, pyroptosis have important role in the regulation of neuronal injury. Microglia are not only central members of the immune regulation of the central nervous system (CNS), but are also involved in the development and homeostatic maintenance of the nervous system. Under various pathological overstimulation, microglia pyroptosis contributes to the massive release of intracellular inflammatory mediators leading to neuroinflammation and ultimately to neuronal damages. In addition, microglia pyroptosis lead to further neurological damage by decreasing the ability to cleanse harmful substances. The pathogenic roles of microglia in a variety of CNS diseases such as neurodegenerative diseases, stroke, multiple sclerosis and depression, and many other neurological disorders have been gradually unveiled. In the context of different neurological disorders, inhibition of microglia pyroptosis by targeting NOD-like receptor family pyrin domain containing (NLRP) 3, caspase-1 and gasdermins (GSDMs) by various chemical agents as well as natural products significantly improve the symptoms or outcome in animal models. This study will provide new ideas for immunomodulatory treatment of CNS diseases.

Dexmedetomidine Inhibits Gasdermin D-Induced Pyroptosis via the PI3K/AKT/GSK3β Pathway to Attenuate Neuroinflammation in Early Brain Injury After Subarachnoid Hemorrhage in Rats

Subarachnoid hemorrhage (SAH) is one kind of life-threatening stroke, which leads to severe brain damage. Pyroptosis plays a critical role in early brain injury (EBI) after SAH. Previous reports suggest that SAH-induced brain edema, cell apoptosis, and neuronal injury could be suppressed by dexmedetomidine (Dex). In this study, we used a rat model of SAH to investigate the effect of Dex on pyroptosis in EBI after SAH and to determine the mechanisms involved. Pyroptosis was found in microglia in EBI after SAH. Dex significantly alleviated microglia pyroptosis via reducing pyroptosis executioner GSDMD and inhibited the release of proinflammatory cytokines induced by SAH. Furthermore, the reduction of GSDMD by Dex was abolished by the PI3K inhibitor LY294002. In conclusion, our data demonstrated that Dex reduces microglia pyroptosis in EBI after SAH via the activation of the PI3K/AKT/GSK3β pathway.

Talaromyces marneffei activates the AIM2-caspase-1/-4-GSDMD axis to induce pyroptosis in hepatocytes

Talaromyces marneffei tends to induce systemic infection in immunocompromised individuals, which is one of the causes of the high mortality. The underlying molecular mechanisms of T.marneffei-induced abnormal liver function are still poorly understood. In this study, we found that T.marneffei-infected patients could develop abnormal liver function, evidenced by reduced albumin and increased levels of aspartate aminotransferase (AST) and AST/alanine aminotransferase (ALT). T. marneffei-infected mice exhibited similar characteristics. In vitro investigations showed that T.marneffei induced the death of AML-12 cells. Furthermore, we determined that T.marneffei infection induced pyroptosis in hepatocytes of C57BL/6J mice and AML-12 cells, demonstrated by the increase of AIM2, caspase-1/-4, Gasdermin D(GSDMD) and pyroptosis-related cytokines in T.marneffei-infected mice/cells. Importantly, cell death was markedly suppressed in the presence of VX765 (an inhibitor of caspase-1/-4). Furthermore, in the presence of VX765, T.marneffei-induced pyroptosis was blocked. Nevertheless, necroptosis and apoptosis were also detected in infected animal model at 14 days post-infection. In conclusion, T.marneffei induces pyroptosis in hepatocytes through activation of the AIM2-caspase-1/-4-GSDMD axis, which may be an important cause of liver damage, and other death pathways including necroptosis and apoptosis may also be involved in the later stage of infection.