Inhibition of neutrophil extracellular trap formation ameliorates neuroinflammation and neuronal apoptosis via STING-dependent IRE1α/ASK1/JNK signaling pathway in mice with traumatic brain injury

Mitophagy in acute central nervous system injuries: regulatory mechanisms and therapeutic potentials

Acute central nervous system injuries, including ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, traumatic brain injury, and spinal cord injury, are a major global health challenge. Identifying optimal therapies and improving the long-term neurological functions of patients with acute central nervous system injuries are urgent priorities. Mitochondria are susceptible to damage after acute central nervous system injury, and this leads to the release of toxic levels of reactive oxygen species, which induce cell death. Mitophagy, a selective form of autophagy, is crucial in eliminating redundant or damaged mitochondria during these events. Recent evidence has highlighted the significant role of mitophagy in acute central nervous system injuries. In this review, we provide a comprehensive overview of the process, classification, and related mechanisms of mitophagy. We also highlight the recent developments in research into the role of mitophagy in various acute central nervous system injuries and drug therapies that regulate mitophagy. In the final section of this review, we emphasize the potential for treating these disorders by focusing on mitophagy and suggest future research paths in this area.

Exploring Molecular Pathways in Exercise-Induced Recovery from Traumatic Brain Injury

Traumatic brain injury (TBI) is functional damage or brain injury due to external forces and is a leading cause of death and disability in children and adults. It causes disruption of the blood-brain barrier (BBB), infiltration of peripheral blood cells, oxidative stress, neuroinflammation and apoptosis, neural excitotoxicity, and mitochondrial dysfunction. Studies have shown that PE can be applied as a non-pharmacological therapy and effectively improve functional recovery from TBI. Recovery from TBI can benefit from both pre- or post-TBI exercise through various mechanisms for neurorepair and rehabilitation of behavior and cognition, including alleviation of TBI-induced oxidative stress, upregulation of heat-shock proteins, reduction of TBI-induced inflammation, promotion of secretion of neurotrophic factors to facilitate neural regeneration, suppression of TBI-induced apoptosis to reduce brain injury, and stabilization of mitochondrial function for better cellular function. This review article provides an overview of the effect of pre- and post-TBI exercise on recovery of neurofunctions and cognition following TBI, summarizes the potential regulatory networks and cellular and biological processes involved in recovery of brain functions, and outlines the molecular mechanisms underlying exercise-induced improvement of TBI, including regulation of gene expression and activation of heat-shock proteins and neurotrophic factors under different exercise schemes. These mechanisms involve TBI-induced oxidative stress, upregulation of heat-shock proteins, inflammation, secretion of neurotrophic factors, and TBI-induced apoptosis. Due to high heterogeneity in human TBI, the outcome of exercise intervention is affected by the injury type and severity of TBI. More studies are needed to investigate the application of various exercise approaches that fits TBI under different circumstances, and to elucidate the detailed pathogenesis mechanisms of TBI to develop more patient-tailored interventions.

The crucial role of neutrophil extracellular traps and IL-17 signaling in indomethacin-induced gastric injury in mice

The homeostasis of gastric mucosa is extremely delicate. Neutrophils, the most abundant immune cells in human circulation, are regarded crutial in the regulation of gastric mucosal immune response. Non-steroidal anti-inflammatory drugs (NSAIDs) induced gastric injury is the second major reason for gastric ulcers. The relations between neutrophils and Indomethacin-induced gastric injury are not fully understood. A mouse model of gastric injury was established using Indomethacin, followed by proteomic analysis (raw data are available via ProteomeXchange with identifier PXD058482). GO functional annotations and KEGG pathway enrichment analysis were conducted on significant differential proteins. The formation of neutrophil extracellular traps (NETs) was observed using ELISA and immunofluorescence. TEM, Western blot and Real-time PCR were applied to observe programmed death of gastric epithelial cells (GECs), and ELISA was conducted to measure levels of TNF-α and IL-1β in the gastric tissue. Deoxyribonuclease 1 (DNase 1), a NETs inhibitor, was administered intraperitoneally to inhibit NETs formation. In vitro, neutrophils were isolated from peripheral blood of mice and co-cultured with mouse GECs cell line, different dosage of Indomethacin were added to the culture dish, the levels of inflammatory factors, formation of NETs and GECs programmed death were assessed in vitro. Poly morphonuclear neutrophils (PMN) were extracted from mouse peripheral blood and single-cell RNA-sequencing (scRNA-seq) was further applied (raw data are available via Genome Sequence Archive with identifier CRA020950) to explore the intracellular mechanism of NETs formation. ELISA and immunofluorescence were performed to validate expression of IL-17 signaling pathway. After Indomethacin gavage, obvious gastric injury was observed. Proteomic analysis indicated that NETs formation played a crucial role in Indomethacin-induced gastric injury. Compared to control group, Indomethacin treatment resulted in NETs formation, elevated levels of TNF-α and IL-1β and GECs programmed death. Inhibition of NETs significantly reduced inflammatory factor levels and mitigated gastric injury caused by indomethacin. In vitro, 200 µL, 400 µL and 600 µL of Indomethacin caused excessive NETs formation in neutrophils. Besides, Indomethacin-induced NETs formation led to GECs programmed death in vitro. scRNA-seq revealed that neutrophils enrichment in the peripheral blood of Indomethacin-induced gastric injury and IL-17 signaling might be the key intracellular of NETs formation. Expressions of neutrophil IL-17R and concentration of IL-17 were significantly higher in model group. NETs formation is pivotal in Indomethacin-induced gastric injury, contributing to programmed cell death of GECs and inflammation; IL-17 signaling might be the key intracellular mechanism of NETs formation.

The STING Signaling: A Novel Target for Central Nervous System Diseases

The canonical cyclic GMP-AMP (cGAMP) synthase (cGAS)-Stimulator of Interferon Genes (STING) pathway has been widely recognized as a crucial mediator of inflammation in many diseases, including tumors, infections, and tissue damage. STING signaling can also be activated in a cGAS- or cGAMP-independent manner, although the specific mechanisms remain unclear. In-depth studies on the structural and molecular biology of the STING pathway have led to the development of therapeutic strategies involving STING modulators and their targeted delivery. These strategies may effectively penetrate the blood-brain barrier (BBB) and target STING signaling in multiple central nervous system (CNS) diseases in humans. In this review, we outline both canonical and non-canonical pathways of STING activation and describe the general mechanisms and associations between STING activity and CNS diseases. Finally, we discuss the prospects for the targeted delivery and clinical application of STING agonists and inhibitors, highlighting the STING signaling pathway as a novel therapeutic target in CNS diseases.

Hydrogen combined with needle-embedding therapy alleviates traumatic brain injury by inhibiting NLRP3 inflammasome activation via STING signaling pathway

BACKGROUND

Traumatic brain injury (TBI) is a primary cause of disability and death worldwide and with unmet effective therapies. Molecular hydrogen (H2) exerts latent therapeutic means for TBI. Nevertheless, few studies have illustrated the roles of hydrogen combined with needle-embedding therapy (H2 + NET) in TBI and its exact mechanism remains unclear. Here, we elucidated the underlying mechanisms of H2 + NET in the TBI progression.

METHODS

Controlled cortical impact (CCI) method was conducted to construct TBI mouse model. The mNSS test was used for neurological function measurement. Nissl staining for evaluating neuronal injury, TUNEL assay for determining neuronal apoptosis and ELISA assay was applied for adenosine, ATP level and inflammatory cytokines determination. The relative mRNA levels of inflammatory elements were assessed by qRT-PCR analysis. Iba-1, NLRP3 and STING expression were determined through immunofluorescence staining. The expression of NLRP3 inflammasome related proteins and STING signaling pathway associated proteins were evaluated using Western blot.

RESULTS

H2 or NET treatment mitigated brain injury and reduced brain water content in CCI-induced TBI mouse model. CCI induction promoted microglia activation and inflammatory response, thereby activating the NLRP3 inflammasome activity and STING signaling pathway, which was partly reversed by H2 or NET treatment. However, H2 + NET significantly ameliorated brain oedema, and further inhibited inflammatory response, NLRP3 inflammasome activation and STING pathway activation in TBI mice when compared to the H2 or NET alone treatment group.

CONCLUSION

Hydrogen combined with needle-embedding therapy acts as a promising intervention method for TBI through inhibiting NLRP3 inflammasome activation via STING signaling pathway.

Sex and Genotype Affect Mouse Hippocampal Gene Expression in Response to Blast-Induced Traumatic Brain Injury

Blast-induced traumatic brain injury (bTBI) has been identified as an increasingly prevalent cause of morbidity and mortality in both military and civilian populations over the past few decades. Functional outcomes following bTBI vary widely among individuals, and chronic neurodegenerative effects including cognitive impairments can develop without effective diagnosis and treatment. Genetic predispositions and sex differences may affect gene expression changes in response to bTBI and influence an individual's probability of sustaining long-term damage or exhibiting resilience and tissue repair. Male and female mice from eight genetically diverse and distinct strains (129S1/SvImJ, A/J, C57BL/6J, CAST/EiJ, NOD/ShiLtJ, NZO/HlLtJ, PWK/PhJ, WSB/EiJ) which encompassed 90% of the genetic variability in commercially available laboratory mice were exposed to a single bTBI (180 kPa) using a well-established shock tube system. Subacute changes in hippocampal gene expression due to blast exposure were assessed using RNA-seq at 1-month post-injury. We identified patterns of dysregulation in gene ontology terms and canonical pathways related to mitochondrial function, ribosomal structure, synaptic plasticity, protein degradation, and intracellular signaling that varied by sex and/or strain, including significant changes in genes encoding respiratory complex I of the electron transport chain in male WSB/EiJ mice and the glutamatergic synapse across more than half of our groups. This study represents a multi-level examination of how genetic variability may influence response to bTBI and provides a foundation for the identification of potential therapeutic targets that could be modulated to improve the health of Veterans and others with histories of blast exposures.

Inhibition of S100A8/A9 ameliorates neuroinflammation by blocking NET formation following traumatic brain injury

Traumatic brain injury (TBI) triggers a robust inflammatory response that is closely linked to worsened clinical outcomes. S100A8/A9, also known as calprotectin or myeloid-related protein-8/14 (MRP8/14), is an alarmin primarily secreted by activated neutrophils with potent pro-inflammatory property. In this study, we explored the roles of S100A8/A9 in modulating neuroinflammation and influencing TBI outcomes, delving into the underlying mechanisms. S100A8/A9-enriched neutrophils were present in the injured brain tissue of TBI patients, and elevated plasma levels of S100A8/A9 were correlated with poorer neurological function. Furthermore, using a TBI mouse model, we demonstrated that treatment with the selective S100A8/A9 inhibitor Paquinimod significantly mitigated neuroinflammation and neuronal death, thereby improving the prognosis of TBI mice. Mechanistically, we found that S100A8/A9, in conjunction with neutrophil activation and infiltration into the brain, enhances reactive oxygen species (ROS) production within neutrophils, accelerating PAD4-mediated neutrophil extracellular trap (NET) formation, which in turn exacerbates neuroinflammation. These findings suggest that S100A8/A9 amplifies neuroinflammatory responses by promoting NET formation in neutrophils. Inhibition of S100A8/A9 effectively attenuated NET-mediated neuroinflammation; however, when PAD4 was overexpressed in the brain using adenovirus, leading to an increased formation of NET in the brain, the anti-inflammatory effects of S100A8/A9 inhibition were markedly diminished. Further experiments with PAD4 knockout mice confirmed that the reduction of NETs could substantially alleviate S100A8/A9-driven neuroinflammation. Finally, we established that the suppression of NET formation by S100A8/A9 inhibition is primarily mediated through the AMPK/Nrf2/HO-1 signaling pathway. These findings underscore the critical pathological role of S100A8/A9 in TBI and emphasize the need for further exploration of S100A8/A9 inhibitor Paquinimod as a potential therapeutic strategy for TBI.

The JNK signalling pathway gene BmJun is involved in the regulation of egg quality and production in the silkworm, Bombyx mori

The Jun N-terminal kinase (JNK) signalling pathway has a key role in tissue remodelling during insect metamorphosis by regulating programmed cell death. However, multiple members of the JNK pathway in Lepidoptera remain uncharacterized. In this study, two key genes of the JNK pathway, BmJun and BmFos, were cloned from the silkworm Bombyx mori, a lepidopteran model insect, and their effects on reproductive development were investigated. BmJun and BmFos encode 239 and 380 amino acids, respectively. Both proteins have typical basic leucine zipper domains and form a BmJUN-BmFOS dimer activator protein to exert transcriptional regulation. During the wandering stage of silkworm development, interference in BmJun expression had no effect on pupation, whereas B. mori vitellogenin (BmVg) expression, which is essential for egg development, was suppressed in the fat body and egg laying was significantly reduced. Additionally, numerous eggs appeared shrivelled and deformed, suggesting that they were nutritionally stunted. Inhibition of the JNK pathway caused abnormal pupal metamorphosis, an increase in shrivelled, unfertilized eggs, a decrease in fat body synthesis, and accumulation of BmVg in the ovaries of female B. mori. The results indicated that BmJUN and BmFOS can form an AP-1 dimer. Interfering with BmJun or inhibiting the phosphorylation of BmJUN leads to a reduction in the synthesis of BmVg in the fat body and its accumulation in the ovaries, thereby affecting the quality and production of the progeny eggs. These findings suggest that regulating Jun in the JNK pathway could be a potential way to inhibit female reproduction in Lepidoptera.

Inhibition of neutrophil extracellular traps alleviates blood-brain barrier disruption and cognitive dysfunction via Wnt3/β-catenin/TCF4 signaling in sepsis-associated encephalopathy

BACKGROUND

Neutrophils and neutrophil extracellular traps (NETs) have been identified as crucial contributors in several neuroinflammatory models, such as stroke and traumatic brain injury, but their role in sepsis-associated encephalopathy (SAE) has not been thoroughly investigated.

METHODS

In this study, we established an SAE model using cecal ligation puncture (CLP) surgery to examine neutrophil infiltration and NETs formation. A protein arginine deiminase 4 (PAD4) inhibitor, GSK484, was employed to suppress NETs release. To assess changes in hippocampal gene expression induced by GSK484 treatment in CLP mice, we utilized RNA sequencing (RNA-Seq) combined with bioinformatics analysis. Additionally, the Elisa, cognitive function test, western bolt and immunofluorescence staining were used to measured hippocampal inflammatory cytokine, cognitive function, and the protein levels of tight junctions (TJs) and adherens junctions (AJs) in SAE mice. We also established a Transwell™ co-culture system using bEnd.3 cells and bone marrow-derived neutrophils to examine the effects of GSK484 on endothelial cell function. This comprehensive approach allowed us to evaluate the impact of NETs inhibition on neuroinflammation, cognitive function, and the underlying molecular mechanisms in the CLP-induced SAE model.

RESULTS

Our findings revealed that neutrophils were significantly overactivated, releasing abundant NETs in the hippocampus of CLP-induced SAE mice. Inhibition of NET formation using GSK484 led to reduced neuroinflammatory responses, improved blood-brain barrier (BBB) integrity, and enhanced survival rates and cognitive function in SAE mice. RNA-Seq and bioinformatics analyses identified the Wnt signaling pathway as the most significant pathway affected. Subsequent experiments demonstrated that NETs inhibition alleviated BBB damage primarily by increasing the expression of Occludin, a TJs protein, and promoting the formation of the VCL/β-catenin/VE-cadherin complex at AJs, mediated by the Wnt3/β-catenin/TCF4 signaling pathway.

CONCLUSIONS

Our results suggest that inhibition of NETs may protect BBB permeability and cognitive function through the Wnt3/β-catenin/TCF4 signaling pathway in the context of CLP-induced SAE, which provides a promising strategy for SAE therapy.

Longan Aril polysaccharides ameliorate cognitive impairment in AD mice via restoration of the immune phagocytosis of microglia

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD) belongs to the category of "forgetfulness" or "dementia" in traditional Chinese medicine, and is often caused by deficiency of five zang-viscera. Longan Aril (the aril of Dimocarpus longan Lour., LA) possesses properties beneficial for heart and spleen health, blood nourishment, and mind tranquility, suggesting its potential as a treatment for AD. This study aimed to investigate the therapeutic effects of Longan Aril polysaccharides (LAPs), a primary active constituent of LA, on lipopolysaccharides (LPS) and amyloid β-peptide (Aβ) induced immune tolerance in AD mice. Further, BV2 cells were employed to explore the mechanism of LAPs in improving immune tolerance.

MATERIAL AND METHODS

LAPs were prepared by water extraction and alcohol precipitation. The monosaccharide composition was determined by high-performance liquid chromatography (HPLC). An AD mouse model of immune tolerance was established by intraperitoneal (i.p) injection of LPS combined with intracerebroventricular (ICV) injection of Aβ25-35. The LAPs group mice received LAPs (1.4 g/kg) daily for 40 days. The anti-AD efficacy and mechanism of LAPs in vivo was evaluated by the Y maze, Morris water maze, Degenerating Neurons Stain (FJC staining), hematoxylin-eosin (H&E) staining, Nissl staining, measurements of lactate, tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) secretion levels, immunofluorescence and western blot. Furthermore, the mechanism of LAPs in improving the function of immune-tolerant BV2 cells was explored in vitro using lactic acid kits, ELISA kits, and western blot. The phagocytic function of BV2 cells was evaluated by the fluorescent dye Alexa Fluor 488 labeled Aβ (AF448-Aβ).

RESULTS

LAPs contained five monosaccharides. LAPs improved cognitive function and increased the number of Nissl bodies, lactate secretion, the IL-10 content, the relative fluorescence intensity of the IBA1 and AXL proteins, and the protein expression levels of AXL, Mertk, Glut1, HK2, PI3K, p-Akt/Akt, p-mTOR/mTOR and HIF-1α of immune-tolerant AD mice. LAPs also reduced the TNF-α content, and the protein expression level of CD68 in immune-tolerant AD mice. In vitro, LAPs elevated the IL-10 content and protein expression levels of PI3K, Akt, p-Akt, and HIF-1α, while reducing lactate secretion and the TNF-α content in immune-tolerant BV2 cells. LAPs promoted the phagocytic activity of BV2 cells, and their effects are completely inhibited by 2-DG and partially inhibited by BAY and Rapa.

CONCLUSIONS

LAPs can enhance the cognitive abilities of immune-tolerant AD mice and diminish their pathological damage. The mechanism involves the regulation of glycolysis and the PI3K/Akt/mTOR/HIF-1α signaling pathway to promote microglial immune phagocytosis.

Zipper-interacting protein kinase mediates neuronal cell death and cognitive dysfunction in traumatic brain injury via regulating DEDD

Neuronal cell death is a causative process in traumatic brain injury (TBI)-induced structural and functional impairment of the central nervous system. However, the upstream trigger of TBI-induced neuronal loss and the underlying molecular pathways remain unclear. Zipper-interacting protein kinase (ZIPK) has been shown to be upregulated in Alzheimer's disease and ischemic stroke and to play a role in cellular apoptosis, while its pathological significance in TBI has not been reported. Herein, we discovered for the first time that ZIPK expression was markedly elevated in neurons after TBI and that ZIPK caused massive neuronal apoptosis in peri-contusional brain regions. Zipk haploinsufficiency antagonized neuronal cell death and reversed several typical neuropathological changes induced by TBI. Mechanistically, we found that ZIPK affected neuronal viability by modulating death effector domain-containing DNA binding protein (DEDD) and caspase-3 pathway. Specifically, ZIPK could bind to and phosphorylate DEDD at the S9 residue, thus enhancing the stability of DEDD, and leading to the activation of caspase-3-mediated apoptotic cascade in neurons. The rescue of neuronal loss by ZIPK downregulation effectively alleviated TBI-induced behavioral deficits by preserving motor and cognitive abilities in vivo, supporting the decisive role of ZIPK dysregulation in TBI-associated neuronal dysfunctions by modulating neuronal survival. Furthermore, pharmacological suppression of ZIPK activity by a specific inhibitor prior to TBI protected neurons from brain injury-induced cell death and neuronal degeneration in vitro and in vivo by preventing DEDD upregulation and caspase-3 activation. In conclusion, our data reveal the essential contribution of ZIPK to TBI-induced neuronal cell death through the DEDD/caspase-3 cascade, and suggest the potential of targeting ZIPK as an effective strategy for treating TBI-related neuropathologies.

cGAS-STING targeting offers novel therapeutic opportunities in neurological diseases

Cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) (cGAMP) synthase (cGAS) is a cytosolic DNA sensor that produces the secondary messenger cGAMP. cGAMP activates the endoplasmic reticulum-associated adaptor stimulator of interferon genes (STING) and activates the innate immune system to produce a type I interferon response. Besides sensing microbial DNA, cGAS can also be activated by self-DNA or endogenous DNA, including that derived from genotoxic extranuclear chromatin and mitochondrially released DNA, indicating that cGAS-STING is an important mechanism in sterile inflammatory responses, autoimmunity, and cellular senescence. However, aberrant activation of the cGAS-STING pathway results in inflammatory and autoimmune diseases. cGAS-STING has emerged as a vital mechanism driving the pathogenesis of inflammation, implicating cGAS-STING signaling in neurological diseases. In this review, we first outline the principal elements of the cGAS-STING signaling cascade, summarizing recent research highlighting how cGAS-STING activation contributes to the pathogenesis of neurological diseases, including various autoimmune, autoinflammatory, and neurodegenerative diseases. Next, we outline selective small-molecule modulators that function as cGAS-STING inhibitors and summarize their mechanisms for treating multiple neurological diseases. Finally, we discuss key limitations of the current therapeutic paradigm and generate possible strategies to overcome them.

NINJ1-mediated plasma membrane rupture of pyroptotic endothelial cells exacerbates blood-brain barrier destruction caused by neutrophil extracellular traps in traumatic brain injury

Brain endothelial cell (bEC) dysfunction is the main factor of blood-brain barrier (BBB) breakdown, which triggers a vicious cycle of aggravating traumatic brain injury (TBI) pathogenesis. Previous studies have revealed that neutrophil extracellular traps (NETs) released by neutrophils can lead to BBB disruption, but there is a lack of research on the underlying mechanisms after TBI. Here, excessive NETs were found in both contused brain tissue and circulation following TBI. We found that NETs could activate the TLR4/NF-κB pathway to induce bEC pyroptosis, which led to BBB disruption after TBI. During this process, ninjurin-1 (NINJ1) was activated in pyroptotic bECs, and it mediated the release of high mobility group box 1 protein (HMGB1) via plasma membrane rupture (PMR) to promote NET formation. NINJ1-mediated release of HMGB1 aggravated NET accumulation by forming a vicious circle following TBI. Knockdown of NINJ1 rescued NET formation, attenuated BBB leakage, and improved neurological outcomes after TBI. NINJ1 may represent a promising target for alleviating NET-induced BBB destruction and other related injuries after TBI.

β2 integrin regulates neutrophil trans endothelial migration following traumatic brain injury

Neutrophils are the first responders among peripheral immune cells to infiltrate the central nervous system following a traumatic brain injury (TBI), triggering neuroinflammation that can exacerbate secondary tissue damage. The precise molecular controls that dictate the inflammatory behavior of neutrophils post-TBI, however, remain largely elusive. Our comprehensive analysis of the molecular landscape surrounding the trauma in TBI mice has revealed a significant alteration in the abundance of β2 integrin (ITGB2), predominantly expressed by neutrophils and closely associated with immune responses. Using the fluid percussion injury (FPI) mouse model, we investigated the therapeutic efficacy of Rovelizumab, an agent that blocks ITGB2. The treatment has demonstrated significant improvements in neurologic function in TBI mice, attenuating blood-brain barrier permeability, mitigating oxidative stress and inflammatory mediator release, and enhancing cerebral perfusion. Moreover, ITGB2 blockade has effectively limited the adherence, migration, and infiltration of neutrophils, and has impeded the formation of neutrophil extracellular traps (NETs) upon their activation. Finally, it was demonstrated that ITGB2 mediates these effects mainly through its interaction with intercellular adhesion molecule-1 (ICAM 1) of endotheliocyte. These findings collectively illuminate ITGB2 as a crucial molecular switch that governs the adverse effects of neutrophils post-TBI and could be targeted to improve clinical outcome in patients.

Mitochondrial DNA leakage: underlying mechanisms and therapeutic implications in neurological disorders

Mitochondrial dysfunction is a pivotal instigator of neuroinflammation, with mitochondrial DNA (mtDNA) leakage as a critical intermediary. This review delineates the intricate pathways leading to mtDNA release, which include membrane permeabilization, vesicular trafficking, disruption of homeostatic regulation, and abnormalities in mitochondrial dynamics. The escaped mtDNA activates cytosolic DNA sensors, especially cyclic gmp-amp synthase (cGAS) signalling and inflammasome, initiating neuroinflammatory cascades via pathways, exacerbating a spectrum of neurological pathologies. The therapeutic promise of targeting mtDNA leakage is discussed in detail, underscoring the necessity for a multifaceted strategy that encompasses the preservation of mtDNA homeostasis, prevention of membrane leakage, reestablishment of mitochondrial dynamics, and inhibition the activation of cytosolic DNA sensors. Advancing our understanding of the complex interplay between mtDNA leakage and neuroinflammation is imperative for developing precision therapeutic interventions for neurological disorders.

Mitochondrial DNA-activated cGAS-STING pathway in cancer: Mechanisms and therapeutic implications

Mitochondrial DNA (mtDNA), a circular double-stranded DNA located within mitochondria, plays a pivotal role in mitochondrial-induced innate immunity, particularly via the cyclic GMP-AMP synthase (cGAS)-STING pathway, which recognizes double-stranded DNA and is crucial for pathogen resistance. Recent studies elucidate the interplay among mtDNA, the cGAS-STING pathway, and neutrophil extracellular traps (NETs) in the context of cancer. mtDNA uptake by recipient cells activates the cGAS-STING pathway, while mtDNA leakage reciprocally regulates NET release, amplifying inflammation and promoting NETosis, a mechanism of tumor cell death. Autophagy modulates these processes by clearing damaged mitochondria and degrading cGAS, thus preventing mtDNA recognition. Tumor microenvironmental factors, such as metabolic reprogramming and lipid accumulation, induce mitochondrial stress, ROS production, and further mtDNA leakage. This review explores strategies in cancer drug development that leverage mtDNA leakage to activate the cGAS-STING pathway, potentially converting 'cold tumors' into 'hot tumors,' while discussing advancements in targeted therapies and proposing new research methodologies.

Inhibition of PAD4-mediated neutrophil extracellular traps formation attenuates hypoxic-ischemic brain injury in neonatal mice

Neonatal hypoxic-ischemic encephalopathy (HIE) is the primary cause of neonatal mortality and severe neurological sequelae. The interaction of neuroinflammation with the immune system represents a significant pathological mechanism underlying the development of HIE. Neutrophil extracellular traps (NETs) are a recently identified antimicrobial mechanism utilized by neutrophils. NETs can act as damage-associated molecular patterns, thereby amplifying the immune response and exerting proinflammatory effects. However, further research is needed to elucidate their role in the pathogenesis of HIE. In this study, we investigated the role of NETs in a hypoxic-ischemic brain injury (HIBI) model. We first reported that a pharmacological intervention to inhibit peptidylarginine deiminase type IV (PAD4) may constitute an effective strategy for reducing HI insult-induced neuroinflammation, neuronal apoptosis, and brain tissue destruction while also enhancing long-term neurobehavioral function in mice. These results support a pathological role for NETs in HIBI, and targeting PAD4 is a potential direction for the treatment of HIE.

Skull bone marrow and skull meninges channels: redefining the landscape of central nervous system immune surveillance

The understanding of neuroimmune function has evolved from concepts of immune privilege and protection to a new stage of immune interaction. The discovery of skull meninges channels (SMCs) has opened new avenues for understanding central nervous system (CNS) immunity. Here, we characterize skull bone marrow and SMCs by detailing the anatomical structures adjacent to the skull, the differences between skull and peripheral bone marrow, mainstream animal processing methods, and the role of skull bone marrow in monitoring various CNS diseases. Additionally, we highlight several unresolved issues based on current research findings, aiming to guide future research directions.

Neutrophil extracellular traps in tumor metabolism and microenvironment

Neutrophil extracellular traps (NETs) are intricate, web-like formations composed of DNA, histones, and antimicrobial proteins, released by neutrophils. These structures participate in a wide array of physiological and pathological activities, including immune rheumatic diseases and damage to target organs. Recently, the connection between NETs and cancer has garnered significant attention. Within the tumor microenvironment and metabolism, NETs exhibit multifaceted roles, such as promoting the proliferation and migration of tumor cells, influencing redox balance, triggering angiogenesis, and driving metabolic reprogramming. This review offers a comprehensive analysis of the link between NETs and tumor metabolism, emphasizing areas that remain underexplored. These include the interaction of NETs with tumor mitochondria, their effect on redox states within tumors, their involvement in metabolic reprogramming, and their contribution to angiogenesis in tumors. Such insights lay a theoretical foundation for a deeper understanding of the role of NETs in cancer development. Moreover, the review also delves into potential therapeutic strategies that target NETs and suggests future research directions, offering new perspectives on the treatment of cancer and other related diseases.

Neutrophil Extracellular Traps Induce Brain Edema Around Intracerebral Hematoma via ERK-Mediated Regulation of MMP9 and AQP4

Perihematomal edema (PHE) significantly aggravates secondary brain injury in patients with intracerebral hemorrhage (ICH), yet its detailed mechanisms remain elusive. Neutrophil extracellular traps (NETs) are known to exacerbate neurological deficits and worsen outcomes after stroke. This study explores the potential role of NETs in the pathogenesis of brain edema following ICH. The rat ICH model was created, immunofluorescence and Western blot were used to examine neutrophil accumulation, NET markers citrullinated histone H3 (CitH3) and myeloperoxidase (MPO), tight junction proteins (ZO-1 and Occludin), Aquaporin-4 (AQP4), matrix metalloproteinase-9 (MMP-9), and ERK phosphorylation (p-ERK) in brain tissues surrounding the hematoma. TUNEL staining and behavioral tests were employed to evaluate neuronal apoptosis and neurological dysfunction, while blood-brain barrier (BBB) permeability and brain edema were also measured by Evans blue and brain water content. Furthermore, the molecular mechanisms related to NETs-induced PHE were investigated using NETs, ERK, MMP-9 and AQP4 regulators, respectively. Ly6G+ neutrophils surrounding the hematoma developed NETs within 3 days post-ICH. NETs decreased tight junction proteins, destroyed BBB integrity, promoted brain edema, increased neuronal apoptosis, and exacerbated neurological deficits. Conversely, inhibition of NETs mitigated PHE, reduced neuronal apoptosis, and improved neurological functions. Mechanistically, NET-induced PHE was originated from impairment of BBB tight junction via ERK/MMP9 pathway, coupled with ERK-mediated AQP4 downregulation in perihematomal regions. These findings elucidated the effects of NETs on PHE, which offered promising insights for targeting NETs to relieve brain edema and secondary brain injury post-ICH.

Neutrophils extracellular traps myeloperoxidase and elastase predict cerebral vasospasms after aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a highly fatal and morbid disease. Despite successful coiling or clipping of a ruptured aneurysm, the patients suffer post-aSAH complications, including early brain injury, cerebral vasospasm (CVS), delayed cerebral ischemia (DCI), and systemic infections that mainly determine the clinical outcomes. Diagnostic biomarkers to predict accurately post-aSAH complications are needed. In this prospective exploratory study, we investigated the predictive value of neutrophil extracellular traps (NETs) components for CVS after aSAH. In the study, 62 patients with aSAH, 17 patients with unruptured cerebral aneurysms, and 12 healthy controls were included. The serum levels of myeloperoxidase (MPO), elastase (ELA), and citrullinated histone H3 (cH3) on day 1 and day 4 of hospital admission were measured with ELISA. Data were scaled using the Yeo-Johnson transformation. Values in two groups were compared using a t-test and in multiple groups using ANOVA. Logistic regression was used to model the outcome probability, including CVS, as the function of ELISA values. Among the patients with aneurysms, those who suffered aSAH had significantly higher levels of MPO (113.9 ± 294.4 vs. 422.3 ± 319.0 ng/ml, p < 0.05), ELA (84.8 ± 221.0 vs. 199.2 ± 218.9 ng/ml, p < 0.05), and cH3 (0.0 ± 0.0 vs. 2.8 ± 1.5, ng/ml, p < 0.05) on day one after aSAH, suggesting the involvement of NETs components in pathophysiology of aSAH and the events following aSAH. Individually, MPO and ELA levels taken on day 1 after SAH did not differ between patients with CVS and patients without CVS. However, when taken together into a logistic model, they allowed for predicting CVS with high sensitivity (91 %) and specificity (79 %). MPO and ELA, along with other clinical parameters, can be used as early predictors of CVS in aSAH patients and can serve as guidance during treatment decisions in the management of aSAH.

PRKDC regulates cGAMP to enhance immune response in lung cancer treatment

Background

Despite its involvement in nucleotide metabolism, tumor immune landscape, and immunotherapy response, the role of 2'-3'-cyclic guanosine monophosphate-adenosine monophosphate (2',3'-cGAMP) in lung adenocarcinoma (LUAD) remails unelucidated. This study aimed to investigate the antitumor effects of 2',3'-cGAMP in LUAD.

Method

Herein, patients with LUAD were screened for prognostic biomarkers, which were then assessed for sensitivity to immunotherapy and chemotherapy utilizing the "TIDE" algorithm and CellMiner database. The results were validated using a mouse xenograft model. Additionally, macrophages and lung cancer cells were co-cultured, and macrophage polarization and apoptosis levels in the lung cancer cells were detected through flow cytometry. Protein levels were analyzed through western blotting and immunofluorescence. Finally, drug-encapsulated nanoparticles were designed to systematically examine the antitumor efficacy of the treatment against LUAD.

Result

Notably, 2',3'-cGAMP-mediated protein kinase, DNA-activated, catalytic subunit (PRKDC) inhibition induced macrophage polarization toward the M1 phenotype, thereby triggering apoptosis in LUAD cells. Furthermore, in vivo experiments showed that M1 macrophage infiltration enhancement and apoptosis induction in lung cancer cells were achieved by suppressing PRKDC expression via 2',3'-cGAMP, which inhibited lung cancer growth. The machine-learning approaches revealed SB505124 to be an effective antitumor agent in LUAD cells with high PRKDC levels owing to its ability to promote 2',3'-cGAMP-mediated apoptosis. Encapsulation of 2',3'-cGAMP, and SB505124 within a nano-delivery system markedly reduced tumor volumes in murine lung cancer tissues compared with that by individual agents.

Conclusion

The findings of this study reveal that PRKDC can predict poor survival of patients with LUAD. Additionally, SB505124 enhances the efficacy of 2',3'-cGAMP-based immunotherapy in patients exhibiting a high PRKDC expression.

PIGK defects induce apoptosis in Purkinje cells and acceleration of neuroectodermal differentiation

Biallelic mutations in PIGK cause GPI biosynthesis defect 22 (GPIBD22), characterized with developmental delay, hypotonia, and cerebellar atrophy. The understanding of the underlying causes is limited due to the lack of suitable disease models. To address this gap, we generated a mouse model with PIGK deficits, specifically in Purkinje cells (Pcp2-cko) and an induced pluripotent stem cell (iPSC) model using the c.87dupT mutant (KI) found in GPIBD22 patients. Pcp2-cko mice demonstrated cerebellar atrophy, ataxia and progressive Purkinje cells loss which were accompanied by increased apoptosis and neuroinflammation. Similarly, KI iPSCs exhibited increased apoptosis and accelerated neural rosette formation, indicating that PIGK defects could impact early neural differentiation that confirmed by the RNA-Seq results of neural progenitor cells (NPCs). The increased apoptosis and accelerated NPC differentiation in KI iPSCs are associated with excessive unfolded protein response (UPR) pathway activation, and can be rescued by UPR pathway inhibitor. Our study reveals potential pathogenic mechanism of GPIBD22 and providing new insights into the therapeutic strategy for GPIBD.

Inhibition of mitochondrial over-division by (+)-14,15-Dehydrovincamine attenuates cisplatin-induced acute kidney injury via the JNK/Mff pathway

Cisplatin-induced acute kidney injury (AKI) is characterized by mitochondrial damage and apoptosis, and safe and effective therapeutic agents are urgently needed. Renal tubular epithelial cells, the main site of AKI, are enriched with a large number of mitochondria, which are crucial for the progression of AKI with an impaired energy supply. Vincamine has anti-inflammatory and antioxidant effects in mouse AKI models. As a natural compound derived from Tabernaemontana pandacaqui, (+)-14, 15-Dehydrovincamine and Vincamine differ in structure by only one double bond, and the role and exact mechanism of (+)-14, 15-Dehydrovincamine remains to be elucidated in AKI. The present study demonstrated that (+)-14,15-Dehydrovincamine significantly ameliorated mitochondrial dysfunction and maintained mitochondrial homeostasis in a cisplatin-induced AKI model. Furthermore, (+)-14,15-Dehydrovincamine ameliorates cytochrome C-dependent apoptosis in renal tubular epithelial cells. c-Jun NH2-terminal kinase (JNK) was identified as a potential target protein of (+)-14,15-Dehydrovincamine attenuating AKI by network pharmacological analysis. (+)-14,15-Dehydrovincamine inhibited cisplatin-induced JNK activation, mitochondrial fission factor (Mff) phosphorylation, and dynamin-related protein 1 (Drp1) translocation to the mitochondria in renal tubular epithelial cells. Meanwhile, the JNK activator anisomycin restored Mff phosphorylation and Drp1 translocation, counteracting the protective effect of (+)-14,15-Dehydrovincamine on mitochondrial dysfunction in cisplatin-induced TECs injury. In conclusion, (+)-14,15-Dehydrovincamine reduced mitochondrial fission, maintained mitochondrial homeostasis, and attenuated apoptosis by inhibiting the JNK/Mff/Drp1 pathway, which in turn ameliorated cisplatin-induced AKI.

Enhancing neurogenesis after traumatic brain injury: The role of adenosine kinase inhibition in promoting neuronal survival and differentiation

Traumatic brain injury (TBI) presents a significant public health challenge, necessitating innovative interventions for effective treatment. Recent studies have challenged conventional perspectives on neurogenesis, unveiling endogenous repair mechanisms within the adult brain following injury. However, the intricate mechanisms governing post-TBI neurogenesis remain unclear. The microenvironment of an injured brain, characterized by astrogliosis, neuroinflammation, and excessive cell death, significantly influences the fate of newly generated neurons. Adenosine kinase (ADK), the key metabolic regulator of adenosine, emerges as a crucial factor in brain development and cell proliferation after TBI. This study investigates the hypothesis that targeting ADK could enhance brain repair, promote neuronal survival, and facilitate differentiation. In a TBI model induced by controlled cortical impact, C57BL/6 male mice received intraperitoneal injections of the small molecule ADK inhibitor 5-iodotubercidin (ITU) for three days following TBI. To trace the fate of TBI-associated proliferative cells, animals received intraperitoneal injections of BrdU for seven days, beginning immediately after TBI. Our results show that ADK inhibition by ITU improved brain repair 14 days after injury as evidenced by a diminished injury size. Additionally, the number of mature neurons generated after TBI was increased in ITU-treated mice. Remarkably, the TBI-associated pathological events including astrogliosis, neuroinflammation, and cell death were arrested in ITU-treated mice. Finally, ADK inhibition modulated cell death by regulating the PERK signaling pathway. Together, these findings demonstrate a novel therapeutic approach to target multiple pathological mechanisms involved in TBI. This research contributes valuable insights into the intricate molecular mechanisms underlying neurogenesis and gliosis after TBT.

Brain-Region-Specific Differences in Protein Citrullination/Deimination in a Pre-Motor Parkinson's Disease Rat Model

The detection of early molecular mechanisms and potential biomarkers in Parkinson's disease (PD) remains a challenge. Recent research has pointed to novel roles for post-translational citrullination/deimination caused by peptidylarginine deiminases (PADs), a family of calcium-activated enzymes, in the early stages of the disease. The current study assessed brain-region-specific citrullinated protein targets and their associated protein-protein interaction networks alongside PAD isozymes in the 6-hydroxydopamine (6-OHDA) induced rat model of pre-motor PD. Six brain regions (cortex, hippocampus, striatum, midbrain, cerebellum and olfactory bulb) were compared between controls/shams and the pre-motor PD model. For all brain regions, there was a significant difference in citrullinated protein IDs between the PD model and the controls. Citrullinated protein hits were most abundant in cortex and hippocampus, followed by cerebellum, midbrain, olfactory bulb and striatum. Citrullinome-associated pathway enrichment analysis showed correspondingly considerable differences between the six brain regions; some were overlapping for controls and PD, some were identified for the PD model only, and some were identified in control brains only. The KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways identified in PD brains only were associated with neurological, metabolic, immune and hormonal functions and included the following: "Axon guidance"; "Spinocerebellar ataxia"; "Hippo signalling pathway"; "NOD-like receptor signalling pathway"; "Phosphatidylinositol signalling system"; "Rap1 signalling pathway"; "Platelet activation"; "Yersinia infection"; "Fc gamma R-mediated phagocytosis"; "Human cytomegalovirus infection"; "Inositol phosphate metabolism"; "Thyroid hormone signalling pathway"; "Progesterone-mediated oocyte maturation"; "Oocyte meiosis"; and "Choline metabolism in cancer". Some brain-region-specific differences were furthermore observed for the five PAD isozymes (PADs 1, 2, 3, 4 and 6), with most changes in PAD 2, 3 and 4 when comparing control and PD brain regions. Our findings indicate that PAD-mediated protein citrullination plays roles in metabolic, immune, cell signalling and neurodegenerative disease-related pathways across brain regions in early pre-motor stages of PD, highlighting PADs as targets for future therapeutic avenues.

Intricate Role of the Cyclic Guanosine Monophosphate Adenosine Monophosphate Synthase-Stimulator of Interferon Genes (cGAS-STING) Pathway in Traumatic Brain Injury-Generated Neuroinflammation and Neuronal Death

The secondary insult in the aftermath of traumatic brain injury (TBI) causes detrimental and self-perpetuating alteration in cells, resulting in aberrant function and the death of neuronal cells. The secondary insult is mainly driven by activation of the neuroinflammatory pathway. Among several classical pathways, the cGAS-STING pathway, a primary neuroinflammatory route, encompasses the cyclic GMP-AMP synthase (cGAS), stimulator of interferon genes (STING), and downstream signaling adaptor. Recently, the cGAS-STING research domain has gained exponential attention. The aberrant stimulation of cGAS-STING machinery and corresponding neuroinflammation have also been reported after TBI. In addition to the critical contribution to neuroinflammation, the cGAS-STING signaling also provokes neuronal cell death through various cell death mechanisms. This review highlights the structural and molecular mechanisms of the cGAS-STING machinery associated with TBI. We also focus on the intricate relationship and framework between cGAS-STING signaling and cell death mechanisms (autophagy, apoptosis, pyroptosis, ferroptosis, and necroptosis) in the aftermath of TBI. We suggest that the targeting of cGAS-STING signaling may open new therapeutic strategies to combat neuroinflammation and neurodegeneration in TBI.

ABBV-744 alleviates LPS-induced neuroinflammation via regulation of BATF2-IRF4-STAT1/3/5 axis

Suppression of neuroinflammation using small molecule compounds targeting the key pathways in microglial inflammation has attracted great interest. Recently, increasing attention has been gained to the role of the second bromodomain (BD2) of the bromodomain and extra-terminal (BET) proteins, while its effect and molecular mechanism on microglial inflammation has not yet been explored. In this study, we evaluated the therapeutic effects of ABBV-744, a BD2 high selective BET inhibitor, on lipopolysaccharide (LPS)-induced microglial inflammation in vitro and in vivo, and explored the key pathways by which ABBV-744 regulated microglia-mediated neuroinflammation. We found that pretreatment of ABBV-744 concentration-dependently inhibited the expression of LPS-induced inflammatory mediators/enzymes including NO, TNF-α, IL-1β, IL-6, iNOS, and COX-2 in BV-2 microglial cells. These effects were validated in LPS-treated primary microglial cells. Furthermore, we observed that administration of ABBV-744 significantly alleviated LPS-induced activation of microglia and transcriptional levels of pro-inflammatory factors TNF-α and IL-1β in mouse hippocampus and cortex. RNA-Sequencing (RNA-seq) analysis revealed that ABBV-744 induced 508 differentially expressed genes (DEGs) in LPS-stimulated BV-2 cells, and gene enrichment and gene expression network analysis verified its regulation on activated microglial genes and inflammatory pathways. We demonstrated that pretreatment of ABBV-744 significantly reduced the expression levels of basic leucine zipper ATF-like transcription factor 2 (BATF2) and interferon regulatory factor 4 (IRF4), and suppressed JAK-STAT signaling pathway in LPS-stimulated BV-2 cells and mice, suggesting that the anti-neuroinflammatory effect of ABBV-744 might be associated with regulation of BATF2-IRF4-STAT1/3/5 pathway, which was confirmed by gene knockdown experiments. This study demonstrates the effect of a BD2 high selective BET inhibitor, ABBV-744, against microglial inflammation, and reveals a BATF2-IRF4-STAT1/3/5 pathway in regulation of microglial inflammation, which might provide new clues for discovery of effective therapeutic strategy against neuroinflammation.

Significance of Programmed Cell Death Pathways in Neurodegenerative Diseases

Programmed cell death (PCD) is a form of cell death distinct from accidental cell death (ACD) and is also referred to as regulated cell death (RCD). Typically, PCD signaling events are precisely regulated by various biomolecules in both spatial and temporal contexts to promote neuronal development, establish neural architecture, and shape the central nervous system (CNS), although the role of PCD extends beyond the CNS. Abnormalities in PCD signaling cascades contribute to the irreversible loss of neuronal cells and function, leading to the onset and progression of neurodegenerative diseases. In this review, we summarize the molecular processes and features of different modalities of PCD, including apoptosis, necroptosis, pyroptosis, ferroptosis, cuproptosis, and other novel forms of PCD, and their effects on the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), multiple sclerosis (MS), traumatic brain injury (TBI), and stroke. Additionally, we examine the key factors involved in these PCD signaling pathways and discuss the potential for their development as therapeutic targets and strategies. Therefore, therapeutic strategies targeting the inhibition or facilitation of PCD signaling pathways offer a promising approach for clinical applications in treating neurodegenerative diseases.

Apoptosis Signal-Regulated Kinase-1 Promotes Nucleus Pulposus Cell Senescence and Apoptosis to Regulate Intervertebral Disc Degeneration

This study investigated the role of apoptosis signal-regulated kinase-1 (ASK1) in intervertebral disc degeneration (IDD). The nucleus pulposus (NP) tissues of non-IDD and IDD patients were subjected to hematoxylin and eosin, Safranin O-fast green, and immunohistochemical staining. Quantitative real-time PCR was used to assess the ASK1 mRNA level within NP tissue samples and cells. The Cell Counting Kit-8 assay, senescence-associated β-galactosidase staining, and flow cytometry were conducted to assess the viability, senescence, and apoptosis of NP cells, respectively. Extracellular matrix-related factors were detected using Western blot analysis. Furthermore, the effect of ASK1 on the IDD rat model was evaluated. Finally, c-Jun N-terminal kinase (JNK) inhibitors were used to verify the effect of the JNK/p38 signaling on IDD. ASK1 mRNA and protein were up-regulated within NP tissue samples from the IDD group, IL-1β-stimulated NP cells, and IDD rats. ASK1 inhibition promoted cell viability and repressed the senescence and apoptosis of NP cells, promoted collagen II and aggrecan, inhibited matrix metalloproteinase 3/9 and a disintegrin and metalloproteinase with thrombospondin motifs 4/5 protein levels, and increased NP cells in rat intervertebral disc tissues. ASK1 overexpression exerted the opposite effects of ASK1 inhibition on NP cells. Additionally, JNK/p38 signaling suppression could reverse the ASK1 up-regulation-induced dysfunction. In conclusion, ASK1 facilitated the senescence and apoptosis of NP cells in promoting IDD progression via the JNK/p38 pathway.

Activation of the sigma-1 receptor ameliorates neuronal ferroptosis via IRE1α after spinal cord injury

Spinal Cord Injury (SCI) is a debilitating disease associated with a significant economic burden owing to its high level of disability; however, current treatment options have only limited efficacy. Past research has shown that iron-dependent programmed cell death, also known as ferroptosis, plays a critical role in the pathogenesis of SCI. The sigma-1 receptor (Sig-1R) is widely distributed in the central nervous system, and has been implicated in the pathophysiology of several neurological and psychiatric disorders. Several in vivo and ex vivo studies have shown that Sig-1R activation exerts unique neuroprotective effects. However, the underlying mechanisms remain unclear. To date, no study has yet demonstrated the association between Sig-1R activation and ferroptosis in patients with SCI. However, the present study found that Sig-1R activation effectively promoted the recovery of motor function in mice after spinal cord injury, attenuated neuronal apoptosis, reduced the production of pro-inflammatory cytokines and iron accumulation, and inhibited ferroptosis in spinal cord tissues following SCI in mice. Ferroptosis and IRE1α were significantly upregulated after spinal cord injury, while sigma-1 receptor agonists were able to facilitate this result through the elimination of inositol-requiring enzyme-1 alpha (IRE1α)-mediated neuronal ferroptosis. Therefore, sigma-1 receptor activation could attenuate ferroptosis after SCI by reducing IRE1α and improving functional recovery after SCI, potentially representing a new therapeutic strategy for treating SCI.

Identification of toll-like receptor 2 as a key regulator of neuronal apoptosis in vascular dementia by bioinformatics analysis and experimental validation

BACKGROUND

Vascular dementia (VaD), the second most prevalent type of dementia, lacks a well-defined cause and effective treatment. Our objective was to utilize bioinformatics analysis to discover the fundamental disease-causing genes and pathological mechanisms in individuals diagnosed with VaD.

METHODS

To identify potential pathogenic genes associated with VaD, we conducted weighted gene co-expression network analysis (WGCNA), differential expression analysis, and protein-protein interaction (PPI) analysis. The exploration of potential biological mechanisms involved the utilization of Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis. Moreover, a bilateral common carotid artery stenosis (BCAS) mouse model of VaD was established, and the expression of the hub gene, its relationship with cognitive function and its potential pathogenic mechanism were verified by cognitive behavior tests, cerebral blood flow measurement, Western blotting, and immunofluorescence experiments.

RESULTS

This study identified 293 DEGs from the brain cortex of VaD patients and healthy controls, among these genes, the Toll-like receptor 2 (TLR2) gene was identified as hub gene, and it was associated with the apoptosis-related pathway PI3K/AKT.The BCAS model demonstrated that the use of TLR2 inhibitors greatly enhanced the cognitive function of the mice (p < 0.05). Additionally, there was a notable decrease in the number of apoptotic cells in the brain cortex of the mice (p < 0.01). Moreover, significant alterations in the levels of proteins related to the PI3K/AKT pathway and cleaved-caspase3 proteins were detected (p < 0.05).

CONCLUSIONS

TLR2 plays a role in the pathophysiology of VaD by enhancing the neuronal apoptotic pathway, suggesting it could be a promising therapeutic target.

Cytosolic Escape of Mitochondrial DNA Triggers cGAS-STING Pathway-Dependent Neuronal PANoptosis in Response to Intermittent Hypoxia

Intermittent hypoxia (IH) is the predominant pathophysiological disturbance in obstructive sleep apnea (OSA), characterized by neuronal cell death and neurocognitive impairment. We focus on the accumulated mitochondrial DNA (mtDNA) in the cytosol, which acts as a damage-associated molecular pattern (DAMP) and activates the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, a known trigger for immune responses and neuronal death in degenerative diseases. However, the specific role and mechanism of the mtDNA-cGAS-STING axis in IH-induced neural damage remain largely unexplored. Here, we investigated the involvement of PANoptosis, a novel type of programmed cell death linked to cytosolic mtDNA accumulation and the cGAS-STING pathway activation, in neuronal cell death induced by IH. Our study found that PANoptosis occurred in primary cultures of hippocampal neurons and HT22 cell lines exposed to IH. In addition, we discovered that during IH, mtDNA released into the cytoplasm via the mitochondrial permeability transition pore (mPTP) activates the cGAS-STING pathway, exacerbating PANoptosis-associated neuronal death. Pharmacologically inhibiting mPTP opening or depleting mtDNA significantly reduced cGAS-STING pathway activation and PANoptosis in HT22 cells under IH. Moreover, our findings indicated that the cGAS-STING pathway primarily promotes PANoptosis by modulating endoplasmic reticulum (ER) stress. Inhibiting or silencing the cGAS-STING pathway substantially reduced ER stress-mediated neuronal death and PANoptosis, while lentivirus-mediated STING overexpression exacerbated these effects. In summary, our study elucidates that cytosolic escape of mtDNA triggers cGAS-STING pathway-dependent neuronal PANoptosis in response to IH, mainly through regulating ER stress. The discovery of the novel mechanism provides theoretical support for the prevention and treatment of neuronal damage and cognitive impairment in patients with OSA.

STING-Dependent Signaling in Microglia or Peripheral Immune Cells Orchestrates the Early Inflammatory Response and Influences Brain Injury Outcome

While originally identified as an antiviral pathway, recent work has implicated that cyclic GMP-AMP-synthase-Stimulator of Interferon Genes (cGAS-STING) signaling is playing a critical role in the neuroinflammatory response to traumatic brain injury (TBI). STING activation results in a robust inflammatory response characterized by the production of inflammatory cytokines called interferons, as well as hundreds of interferon stimulated genes (ISGs). Global knock-out (KO) mice inhibiting this pathway display neuroprotection with evidence that this pathway is active days after injury; yet, the early neuroinflammatory events stimulated by STING signaling remain understudied. Furthermore, the source of STING signaling during brain injury is unknown. Using a murine controlled cortical impact (CCI) model of TBI, we investigated the peripheral immune and microglial response to injury utilizing male chimeric and conditional STING KO animals, respectively. We demonstrate that peripheral and microglial STING signaling contribute to negative outcomes in cortical lesion volume, cell death, and functional outcomes postinjury. A reduction in overall peripheral immune cell and neutrophil infiltration at the injury site is STING dependent in these models at 24 h. Transcriptomic analysis at 2 h, when STING is active, reveals that microglia drive an early, distinct transcriptional program to elicit proinflammatory genes including interleukin 1-β (IL-1β), which is lost in conditional knock-out mice. The upregulation of alternative innate immune pathways also occurs after injury in these animals, which supports a complex relationship between brain-resident and peripheral immune cells to coordinate the proinflammatory response and immune cell influx to damaged tissue after injury.

Neuroinflammation and acquired traumatic CNS injury: a mini review

Acquired traumatic central nervous system (CNS) injuries, including traumatic brain injury (TBI) and spinal cord injury (SCI), are devastating conditions with limited treatment options. Neuroinflammation plays a pivotal role in secondary damage, making it a prime target for therapeutic intervention. Emerging therapeutic strategies are designed to modulate the inflammatory response, ultimately promoting neuroprotection and neuroregeneration. The use of anti-inflammatory agents has yielded limited support in improving outcomes in patients, creating a critical need to re-envision novel approaches to both quell deleterious inflammatory processes and upend the progressive cycle of neurotoxic inflammation. This demands a comprehensive exploration of individual, age, and sex differences, including the use of advanced imaging techniques, multi-omic profiling, and the expansion of translational studies from rodents to humans. Moreover, a holistic approach that combines pharmacological intervention with multidisciplinary neurorehabilitation is crucial and must include both acute and long-term care for the physical, cognitive, and emotional aspects of recovery. Ongoing research into neuroinflammatory biomarkers could revolutionize our ability to predict, diagnose, and monitor the inflammatory response in real time, allowing for timely adjustments in treatment regimens and facilitating a more precise evaluation of therapeutic efficacy. The management of neuroinflammation in acquired traumatic CNS injuries necessitates a paradigm shift in our approach that includes combining multiple therapeutic modalities and fostering a more comprehensive understanding of the intricate neuroinflammatory processes at play.

Crosstalk between neutrophil extracellular traps and immune regulation: insights into pathobiology and therapeutic implications of transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-associated death, occurring during or within 6 hours after transfusion. Reports indicate that TRALI can be categorized as having or lacking acute respiratory distress syndrome (ARDS) risk factors. There are two types of TRALI in terms of its pathogenesis: antibody-mediated and non-antibody-mediated. The key initiation steps involve the priming and activation of neutrophils, with neutrophil extracellular traps (NETs) being established as effector molecules formed by activated neutrophils in response to various stimuli. These NETs contribute to the production and release of reactive oxygen species (ROS) and participate in the destruction of pulmonary vascular endothelial cells. The significant role of NETs in TRALI is well recognized, offering a potential pathway for TRALI treatment. Moreover, platelets, macrophages, endothelial cells, and complements have been identified as promoters of NET formation. Concurrently, studies have demonstrated that the storage of platelets and concentrated red blood cells (RBC) can induce TRALI through bioactive lipids. In this article, recent clinical and pre-clinical studies on the pathophysiology and pathogenesis of TRALI are reviewed to further illuminate the mechanism through which NETs induce TRALI. This review aims to propose new therapeutic strategies for TRALI, with the hope of effectively improving its poor prognosis.