Activating cGAS-STING axis contributes to neuroinflammation in CVST mouse model and induces inflammasome activation and microglia pyroptosis

Mitochondrial Dysfunction is a Crucial Immune Checkpoint for Neuroinflammation and Neurodegeneration: mtDAMPs in Focus

Neuroinflammation is a pivotal factor in the progression of both age-related and acute neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, and stroke. Mitochondria, essential for neuronal health due to their roles in energy production, calcium buffering, and oxidative stress regulation, become increasingly susceptible to dysfunction under conditions of metabolic stress, aging, or injury. Impaired mitophagy in aged or injured neurons leads to the accumulation of dysfunctional mitochondria, which release mitochondrial-derived damage-associated molecular patterns (mtDAMPs). These mtDAMPs act as immune checkpoints, activating pattern recognition receptors (PRRs) and triggering innate immune signaling pathways. This activation initiates inflammatory responses in neurons and brain-resident immune cells, releasing cytokines and chemokines that damage adjacent healthy neurons and recruit peripheral immune cells, further amplifying neuroinflammation and neurodegeneration. Long-term mitochondrial dysfunction perpetuates a chronic inflammatory state, exacerbating neuronal injury and contributing additional immunogenic components to the extracellular environment. Emerging evidence highlights the critical role of mtDAMPs in initiating and sustaining neuroinflammation, with circulating levels of these molecules potentially serving as biomarkers for disease progression. This review explores the mechanisms of mtDAMP release due to mitochondrial dysfunction, their interaction with PRRs, and the subsequent activation of inflammatory pathways. We also discuss the role of mtDAMP-triggered innate immune responses in exacerbating both acute and chronic neuroinflammation and neurodegeneration. Targeting dysfunctional mitochondria and mtDAMPs with pharmacological agents presents a promising strategy for mitigating the initiation and progression of neuropathological conditions.

Therapeutic targeting the cGAS-STING pathway associated with protein and gene: An emerging and promising novel strategy for aging-related neurodegenerative disease

Neurodegenerative diseases (NDDs) represent a rapidly escalating global health challenge, contributing significantly to the worldwide disease burden and posing substantial threats to public health systems across nations. Among the many risk factors for neurodegeneration, aging is the major risk factor. In the context of aging, multiple factors lead to the release of endogenous DNA (especially mitochondrial DNA, mtDNA), which is an important trigger for the activation of the cGAS-STING innate immune pathway. Recent studies have identified an increasing role for activation of the cGAS-STING signaling pathway as a driver of senescence-associated secretory phenotypes (SASPs) in aging and NDDs. The cGAS-STING pathway mediates the immune sensing of DNA and is a key driver of chronic inflammation and functional decline during the aging process. Blocking cGAS-STING signaling may reduce the inflammatory response by preventing mtDNA release and enhancing mitophagy. Targeted inhibition of the cGAS-STING pathway by biological macromolecules such as natural products shows promise in therapeutic strategies for age-related NDDs. This review aims to systematically and comprehensively introduces the role of the cGAS-STING pathway in age-related NDDs in the context of aging while revealing the molecular mechanisms of the cGAS-STING pathway and its downstream signaling pathways and to develop more targeted and effective therapeutic strategies for NDDs.

Unraveling the cGAS-STING pathway in Alzheimer's disease: A new Frontier in neuroinflammation and therapeutic strategies

Alzheimer's disease (AD) is the most prevalent type of neurological disorder characterized by cognitive decline and memory loss, marked by the accumulation of amyloid beta (Aβ) plaques and hyperphosphorylated tau protein, causing extensive neuronal death and neuroinflammation. There is growing evidence that AD development extends beyond the neuronal compartment and has a major impact on the immunological functions of the brain. The cyclic GMP-AMP synthase (cGAS) detects cytosolic DNA, including pathogenic foreign DNA and self-DNA from cellular injury, triggering a type I interferon (IFN-I) response through activation of the stimulator of interferon genes (STING). The activation of the cGAS-STING pathway in response to mitochondrial dysfunction drives neuroinflammation in AD, which is mediated by the release of IFN-I cytokines. Furthermore, the release of oxidized mtDNA is necessary for the stimulation of the nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome, which is a family of protein complexes that macrophages can produce to induce inflammation. AD becomes severe by the stimulation of the cGAS-STING pathway, which results in sterile inflammation and microglial dysfunction. This review aims to explore the potential impact of the cGAS-STING signaling pathway in the pathogenesis and progression of AD. Additionally; after overviewing recent findings, this article highlights the molecular mechanism involved in the onset of disease and its modulation regarding the therapeutic approach of AD. Finally, deliberated a deep insight, the cGAS-STING axis could provide novel therapeutic avenues for slowing or halting the progression of AD, thereby offering new prospects for treatment development.

Sulfasalazine improves neuronal function in mice with ischemic stroke by inhibiting the STING/NF-κB pathway

Inflammation plays an essential role in the pathological processes of ischemic stroke (IS). Sulfasalazine is used in clinical practice for the treatment of inflammatory diseases. This study investigated the effects of sulfasalazine in mice with IS and its underlying mechanisms. We employed an in vivo mice model of middle cerebral artery occlusion (MCAO)/reperfusion, investigating the impact of sulfasalazine on MCAO mice using tetrazolium chloride (TTC) staining, behavioral experiments, and pathological staining. Utilizing of network pharmacology methodologies, we speculated that the protective effect of sulfasalazine against IS may be related to inflammation. The effects of sulfasalazine on inflammation and polarization in oxygen-glucose deprivation/re-oxygenation (OGD/R)-induced BV2 cells were examined through immunofluorescence and PCR techniques. Additionally, the influence of sulfasalazine on the STING/NF-κB pathway was assessed using Western blot and immunofluorescence techniques. Sulfasalazine significantly reduced the infarct area in MCAO mice, restored cerebral blood flow, and improved motor function in the MCAO mice. Pathological staining results indicated that sulfasalazine can mitigate neuronal damage in the cerebral cortex of MCAO mice. Immunofluorescence and PCR testing showed that sulfasalazine promotes M1 to M2 polarization, and reduces inflammation in OGD/R-induced BV2 cells. Furthermore, the Western blot and immunofluorescence results both confirmed that sulfasalazine can inhibit the activation of the STING/NF-κB pathway. This study elucidated the potential therapeutic role of sulfasalazine in IS through its anti-inflammatory effects and modulation of STING/NF-κB pathway, offering novel insights into treatment strategies for IS.

Unraveling extracellular vesicle DNA: Biogenesis, functions, and clinical implications

Extracellular Vesicles (EVs) have emerged as essential carriers of molecular biomarkers and mediators of intercellular communication. While previous studies have predominantly focused on EV proteins, lipids, and RNA, the role of EV-derived DNA (EV-DNA) remains relatively unexplored. Understanding EV-DNA is crucial, given its association with nearly all EV populations. This review aims to comprehensively summarize existing EV-DNA research, emphasizing its functional significance and potential as a disease biomarker. By bridging the gap in our understanding, we shed light on the origins, structure, localization, and distribution of EV-DNA. We analyze a wide range of studies, investigating EV-DNA across various pathological conditions. Our review encompasses experimental methods, theoretical approaches, and clinical observations, providing a holistic view of EV-DNA research. We discuss the biogenesis mechanisms of different EV subtypes, the available isolation methods for these subtypes, and consider their origins and variability under different conditions. EV-DNA exhibits remarkable stability and reflects genomic alterations, making it a promising candidate for liquid biopsy applications. From cancer diagnostics to treatment monitoring, EV-DNA holds significant potential. The findings underscore the importance of EV-DNA as an innovative biomarker. As research continues, EV-DNA may revolutionize disease detection, prognosis, and therapeutic strategies.

Lactate-induced macrophage HMGB1 lactylation promotes neutrophil extracellular trap formation in sepsis-associated acute kidney injury

BACKGROUND

Neutrophils play a key role in sepsis-associated acute kidney injury (SAKI), a common and life-threatening complication of organ failure. High mobility group box 1 (HMGB1) modulates inflammatory responses and the formation of neutrophil extracellular traps (NETs). The present work aimed to explore whether HMGB1 lactylation promotes NET formation and exacerbates SAKI.

METHODS

Venous blood samples were collected from healthy volunteers and SAKI patients. A SAKI mouse model was established using the cecal ligation and puncture method. A coculture system of macrophage-derived exosomes and neutrophils was established. Macrophage-derived exosomes were isolated and identified. ELISAs, immunofluorescence staining, coimmunoprecipitation, and Western blotting were utilized to determine protein levels.

RESULTS

Elevated blood lactate levels were associated with increased HMGB1 levels in patients with SAKI. In mouse models, lactate increased HMGB1 expression, promoted NET formation, and exacerbated SAKI. Lactate stimulated M1 macrophages to secrete exosomes, leading to the accumulation and release of HMGB1 in the cytoplasm. Additionally, lactate promoted HMGB1 lactylation in macrophages, triggering the release of mitochondrial DNA from neutrophils and activating the cyclic GMP‒AMP synthase/stimulator of interferon genes pathway.

CONCLUSION

This study revealed that lactate-induced HMGB1 lactylation in macrophages plays a role in promoting NET formation in SAKI through the cGAS/STING pathway. These findings suggest that HMGB1 could be a potential target for therapeutic intervention in SAKI.

Transcranial Magnetic Stimulation Alleviates Spatial Learning and Memory Impairment by Inhibiting the Expression of SARM1 in Rats with Cerebral Ischemia-Reperfusion Injury

The cognitive impairment resulting from stroke is purported to be associated with impaired neuronal structure and function. Transcranial Magnetic Stimulation (TMS) modulates neuronal or cortical excitability and inhibits cellular apoptosis, thereby enhancing spatial learning and memory in middle cerebral artery occlusion/reperfusion (MCAO/R) rats. In this study, we aimed to investigate whether Sterile alpha and Toll/interleukin receptor motif-containing protein 1 (SARM1), a pivotal Toll-like receptor adaptor molecule and its related mechanisms are involved in the ameliorating effect of TMS on cognitive function post-cerebral ischemia. We evaluated hippocampal injury in MCAO/R rats after one week of treatment with 10-Hz TMS at an early stage. The effect of SARM1 was more effectively assessed through lentivirus-mediated SARM1 overexpression. Various techniques, including FJB staining, HE staining, western blot, immunofluorescence, imunohistochemistry, and transmission electron microscopy, were employed to investigate the molecular biological and morphological alterations of axons, myelin sheaths and apoptosis in the hippocampus. Ultimately, Morris Water Maze was employed to evaluate the spatial learning and memory capabilities of the rats. We observed that TMS significantly reduced the levels of SARM1, NF-κB, and Bax following MCAO/R, while elevating the levels of HSP70, Bcl-2, GAP-43, NF-200, BDNF, and MBP. Overexpression of SARM1 not only reversed the neuroprotective effects induced by TMS but also exacerbated spatial learning and memory impairments in rats. Our results demonstrate that TMS mitigates hippocampal cell apoptosis via the SARM1/HSP70/NF-κB signaling pathway, thus fostering the regeneration of hippocampal axons and myelin sheaths, as well as the improvement of spatial learning and memory.

Identification of pivotal genes and regulatory networks associated with SAH based on multi-omics analysis and machine learning

Subarachnoid hemorrhage (SAH) is a disease with high mortality and morbidity, and its pathophysiology is complex but poorly understood. To investigate the potential therapeutic targets post-SAH, the SAH-related feature genes were screened by the combined analysis of transcriptomics and metabolomics of rat cortical tissues following SAH and proteomics of cerebrospinal fluid from SAH patients, as well as WGCNA and machine learning. The competitive endogenous RNAs (ceRNAs) and transcription factors (TFs) regulatory networks of the feature genes were constructed and further validated by molecular biology experiments. A total of 1336 differentially expressed proteins were identified, including 729 proteins downregulated and 607 proteins upregulated. The immune microenvironment changed after SAH and the changement persisted at SAH 7d. Through multi-omics and bioinformatics techniques, five SAH-related feature genes (A2M, GFAP, GLIPR2, GPNMB, and LCN2) were identified, closely related to the immune microenvironment. In addition, ceRNAs and TFs regulatory networks of the feature genes were constructed. The increased expression levels of A2M and GLIPR2 following SAH were verified, and co-localization of A2M with intravascular microthrombus was demonstrated. Multiomics and bioinformatics tools were used to predict the SAH associated feature genes confirmed further through the ceRNAs and TFs regulatory network development. These molecules might play a key role in SAH and may serve as potential biological markers and provide clues for exploring therapeutic options.

Targeting microglia-Th17 feed-forward loop to suppress autoimmune neuroinflammation

Microglia and Th17 cells are the major immunopathogenic cells in multiple sclerosis and its animal model of immune aspects, experimental autoimmune encephalomyelitis (EAE). While studies have highlighted the distinct roles of microglia and Th17 cells in EAE, it remains unclear whether microglia, as potential professional antigen-presenting cells, activate and stabilize the effector program of EAE-pathogenic Th17 cells in vivo; and if so, whether the Th17 could in turn reinforce the active state of the microglia. Our data demonstrate in an array of mouse models, including active/passive-EAE and transgenic mice, a microglia-Th17 feed-forward activation loop drives EAE disease progression through a mechanism dependent on both MHC-II, proinflammatory cytokines, inflammatory chemokines as well as STING→NF-κB pathway in the microglia and effector cytokines produced by the pathogenic Th17 cells. We also captured and identified the molecular properties of the feed-forward loop, which are two-cell entities of microglia-Th17, and proved them as the functional units of antigen presentation and bi-directional activation between the two cell types. Moreover, ACT001, an orphan drug to treat glioblastoma, disrupts this feed-forward activation loop by inhibiting the STING→NF-κB pathway in microglia, thereby alleviating EAE. These findings emphasize the importance of interactions and bi-directional activations between microglia and Th17 in the autoimmune neuroinflammation, and provide rationale for further investigation on ACT001 as therapeutic option for autoimmune inflammatory diseases driven by similar mechanisms.

Therapeutic connections between pyroptosis and paclitaxel in anti-tumor effects: an updated review

As a form of inflammation-associated cell death, pyroptosis has gained widespread attention in recent years. Accumulating evidence indicates that pyroptosis regulates tumor growth and is associated with autoimmune disorders and inflammatory response. Paclitaxel, a traditional Chinese medicine, usually induces death of cancer cells as a chemotherapeutic agent. Previous studies have revealed that paclitaxel can exert an anti-tumor effect through a variety of cell death mechanisms, of which pyroptosis plays a pivotal role in inhibiting tumor growth and enhancing anti-tumor immunity. In this review, we summarize the current advances in therapeutic connections between pyroptosis and paclitaxel in anti-tumor effects.

Primary cilia prevent activation of the cGAS-STING pathway during mouse decidualization

Primary cilia are antenna-like organelles that sense extracellular signals and function as signaling hubs essential for vertebrate development and homeostasis. Decidualization is crucial for pregnancy establishment and maintenance in both humans and mice. While primary cilia are present in endometrial stromal cells, their role in pregnancy remains unknown. Here, we identify TMEM67, a key component of the ciliary transition zone, as a critical regulator of mouse decidualization. Loss of primary cilia triggers RhoA-MLC2-dependent actomyosin contraction, which transmits mechanical forces to the nuclear lamina, leading to micronuclei formation. Within these micronuclei, double-stranded DNA (dsDNA) can directly bind to cyclic GMP-AMP synthase (cGAS) in situ, initiating downstream signaling. This activation of the cGAS-STING pathway reduces CCL6 production and impairs decidualization. Furthermore, pharmacological inhibition of actin polymerization or RhoA-ROCK signaling alleviates mechanical forces surrounding stromal cells, restores ciliogenesis, maintains nuclear integrity, suppresses the cGAS-STING pathway activation, and ultimately rescues decidualization. Our findings reveal a previously unrecognized mechanism by which primary cilia regulate the actin cytoskeleton to maintain nuclear integrity and prevent DNA leakage. This safeguards against aberrant activation of the cGAS-STING pathway, which would otherwise trigger detrimental immune signaling and impair decidualization.

Microglial STING activation promotes neuroinflammation and pathological changes in experimental mice with intracerebral haemorrhage

Neuroinflammation, a significant contributor to secondary brain injury, plays a critical role in the pathological process and prognosis of intracerebral haemorrhage (ICH). Thus, developing interventions to mitigate secondary neuroimmune deterioration is of paramount importance. Currently, no effective immunomodulatory drugs are available for ICH. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway is a recently identified innate immune-sensing pathway primarily expressed in microglia within the central nervous system (CNS) that has been implicated in the pathophysiology of various neurological diseases. In this study we investigated the role of cGAS-STING pathway in ICH. A collagenase model of ICH was established in mice. Brain tissues were collected on D1 or D3 post-ICH. We observed a significant increase in double-stranded (dsDNA) levels and activation of the cGAS-STING pathway in the perihaematomal region of ICH mice. Administration of a blood brain barrier-permeable STING antagonist H151 (10 mg/kg, i.p.) significantly decreased cell apoptosis, alleviated hematoma growth, and improved motor impairments in ICH mice, accompanied by inhibiting the STING pathway in microglia, reducing production/release of the cGAS-STING pathway downstream inflammatory factors, NLRP3 inflammasome activation and gasdermin D (GSDMD)-induced microglial pyroptosis. Microglial Sting conditional knockout significantly mitigated ICH-induced neuroinflammatory responses, pathological damage and motor dysfunction. These results suggest that the microglial STING pathway promotes brain pathological damage and behavioural defects in ICH mice by activating the NLRP3 inflammasome and microglial pyroptosis. The STING pathway may serve as a potential therapeutic target for ICH-induced secondary brain injury.

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 sulfide improves poststroke depression-induced inflammation in microglial cells by enhancing endoplasmic reticulum autophagy and inhibiting the cGAS-STING pathway

Poststroke depression (PSD) affects approximately one-third of stroke survivors, contributing to poor outcomes and elevated mortality. This study aimed to investigate the therapeutic effects of hydrogen sulfide (H2S), administered as sodium hydrosulfide (NaHS), on PSD-induced inflammation, with a focus on the modulation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon gene (STING) pathway and the enhancement of endoplasmic reticulum (ER) autophagy in microglial cells. An in-vivo rat model was established to evaluate the effects of NaHS on depression-like behaviors and inflammation. Mechanistic studies were conducted in vitro using BV2 microglia subjected to oxygen-glucose deprivation (OGD) and corticosterone. Key inflammatory markers, cGAS-STING pathway activity, and ER-autophagy-related proteins were analyzed using quantitative reverse transcription PCR, Western blotting, ELISA, transmission electron microscopy, and immunofluorescence staining. Depression-like behaviors in rats were assessed using the forced swimming and tail suspension tests. H2S treatment ameliorated depression-like symptoms, mitigated hippocampal damage, and reduced pro-inflammatory markers, including NOD-like receptor protein 3, interleukin-1β (IL-1β), and IL-18 by inhibiting the cGAS-STING pathway. Furthermore, H2S significantly upregulated autophagy-related proteins (LC3, Beclin-1, and FAM134B) and autophagic vesicles, indicating enhanced ER autophagy. Notably, silencing FAM134B reversed the inhibitory effects of H2S on the cGAS-STING pathway, underscoring the pivotal role of ER autophagy in H2S-mediated neuroprotection. These findings demonstrate that H2S mitigates PSD-induced microglial inflammation and depression-like behaviors by inhibiting the cGAS-STING pathway and promoting ER autophagy, suggesting its potential as a therapeutic strategy for PSD. Further investigation into H2S and autophagy-related pathways could reveal novel therapeutic avenues for neuroinflammatory conditions.

Dual-tDCS Ameliorates Cerebral Injury and Promotes Motor Function Recovery via cGAS-STING Signaling Pathway in a Rat Model of Ischemic Stroke

Ischemic stroke is one of the leading causes of death and disability. Dual transcranial direct current stimulation (dual-tDCS) is a promising intervention to treat ischemic stroke, but its efficacy and underlying mechanism remain to be verified. Cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway has recently emerged as a key mediator in cerebral injury. However, little is known about the effect of cGAS-STING on neuronal damage in ischemic stroke, and it remains to be studied whether the cGAS-STING pathway is involved in tDCS intervention for ischemic stroke. Therefore, we aimed to investigate whether dual-tDCS can alleviate ischemic brain injury in a rat model of ischemic stroke and if so, whether via cGAS-STING pathway. Middle cerebral artery occlusion (MCAO) was employed to induce a rat model of ischemic stroke. Male SD rats weighing 250-280 g were randomly assigned to the Sham, MCAO, Dual-tDCS, Dual-tDCS + RU.521, and Dual-tDCS + 2'3'-cGAMP groups, with 10 rats in each group completing the experiment. Behavioral, morphological, MRI, and molecular biological methods were performed. We found that the cGAS-STING pathway was activated and expressed in neurons after MCAO. Dual-tDCS improved motor function and infarct volume, inhibited neuronal apoptosis, promoted the expression of neurotrophins (BDNF and NGF), CD31, and VEGF, and suppressed inflammation reaction after MCAO via the cGAS-STING pathway. Taken together, dual-tDCS may improve MCAO-induced brain injury and promote the recovery of motor function, resulting from the inhibition of neuronal apoptosis and inflammation reaction, as well as promotion of the expression of nerve plasticity- and angiogenesis-related proteins, via cGAS-STING pathway.

Pyroptosis for osteoarthritis treatment: insights into cellular and molecular interactions inflammatory

Osteoarthritis (OA) is a widely prevalent chronic degenerative disease often associated with significant pain and disability. It is characterized by the deterioration of cartilage and the extracellular matrix (ECM), synovial inflammation, and subchondral bone remodeling. Recent studies have highlighted pyroptosis-a form of programmed cell death triggered by the inflammasome-as a key factor in sustaining chronic inflammation. Central to this process are the inflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18), which play crucial roles mediating intra-articular pyroptosis through the NOD-like receptor protein 3 (NLRP3) inflammasome. This paper investigates the role of the pyroptosis pathway in perpetuating chronic inflammatory diseases and its linkage with OA. Furthermore, it explores the mechanisms of pyroptosis, mediated by nuclear factor κB (NF-κB), the purinergic receptor P2X ligand-gated ion channel 7 (P2X7R), adenosine monophosphate (AMP)-activated protein kinase (AMPK), and hypoxia-inducible factor-1α (HIF-1α). Additionally, it examines the interactions among various cellular components in the context of OA. These insights indicate that targeting the regulation of pyroptosis presents a promising therapeutic approach for the prevention and treatment of OA, offering valuable theoretical perspectives for its effective management.

Mechanistic insights into the neuroprotective effects of low-intensity transcranial ultrasound stimulation in post-cardiac arrest brain injury: Modulation of the Piezo1-Dkk3/PI3K-Akt pathway

Post-cardiac arrest brain injury (PCABI) remains a significant challenge, marked by high mortality and disability rates due to persistent neuroinflammation. This study explored the neuroprotective potential of low-intensity transcranial ultrasound stimulation (LITUS) in mitigating brain damage after cardiopulmonary resuscitation (CPR) using a murine model and in vitro assays. LITUS treatment improved 24-h survival rates and neurological recovery in cardiac arrest (CA) mice, as evidenced by behavioral assessments and reduced neurological deficit scores. Proteomic analyses revealed modulation of Piezo1-Dkk3/PI3K-Akt signaling pathway, characterized by decreased pro-inflammatory cytokines (IL-1β, IL-6, TNF-α). Mechanistic studies demonstrated that LITUS enhanced Piezo1 and Dkk3 activation, promoting calcium influx and anti-inflammatory responses. The Piezo1 antagonist GsMTx4 abrogated these effects, underscoring Piezo1's specific role. Additionally, in vitro experiments using oxygen/glucose deprivation and reoxygenation (OGD/R)-treated BV2 microglial cells confirmed that LITUS reduced inflammatory responses and enhanced cellular recovery via the Piezo1-Dkk3 axis. These findings highlight LITUS as a promising non-invasive therapeutic strategy to ameliorate PCABI by modulating neuroinflammation through the Piezo1-Dkk3/PI3K-Akt pathway. This work provides a basis for translational research and potential clinical applications in improving outcomes for CPR survivors.

cGAS/STING/NLRP3 Signaling Pathway-Mediated Pyroptosis in Hypertrophic Cardiomyopathy Radiotherapy

BACKGROUND

Radiotherapy is a commonly employed treatment modality for cancer; however, its radiobiological effects in hypertrophic cardiomyopathy (HCM) remain unclear. Radiation exposure activates the cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) synthase (cGAS)-stimulator of interferon genes (STING) pathway, which is functionally associated with the activation of NOD-like Receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasomes, known mediators of pyroptotic cell death. Nonetheless, the underlying mechanism requires further investigation. Therefore, the objective of this study is to elucidate the role of the cGAS/STING/NLRP3 pathway in the process of cardiomyocyte pyroptosis during radiotherapy for HCM.

METHODS

Transverse aortic constriction surgery was conducted to establish a mouse model of pressure overload-induced HCM, followed by the administration of 30 Gray (Gy) radiation one-week post-surgery. Cardiac morphology and function were evaluated through echocardiographic techniques. Hematoxylin & Eosin staining, along with Wheat Germ Agglutinin (WGA) staining, were utilized to quantify the cross-sectional area of cardiomyocytes and the degree of left ventricular hypertrophy. The HL-1 mouse cardiac muscle cell line was subjected to 40 Gy of radiation using an X-ray irradiator to establish an in vitro model of HCM, with or without the application of the NLRP3 inhibitor MCC950 and cGAS overexpression. Various assays, including the Cell Counting Kit-8 (CCK8), enzyme-linked immunosorbent assay (ELISA), and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimi- dazolylcarbocyanine iodide (JC-1) probe assays, were performed to assess cell viability, the concentrations of Interleukin (IL)-1β, IL-18, and cGAMP, as well as mitochondrial membrane potential. The morphology of cell membranes and mitochondria was analyzed using scanning electron microscopy (SEM) and fluorescence in situ hybridization (FISH) dual labelling techniques. The expression levels of cGAS, STING, and NLRP3 were evaluated through by western blot analysis.

RESULTS

Radiotherapy reduced cardiac hypertrophy, improved cardiac function, and decreased fibrotic changes in HCM mice when compared to control groups. The application of radiation resulted in pyroptosis in HL-1 cells and a reduction in cell viability; this effect that was alleviated by the inhibition of NLRP3, while overexpression of cGAS exacerbated the situation. Furthermore, radiation led to a decline in mitochondrial membrane potential and the leakage of mitochondrial DNA into the cytoplasm, which activated the cGAS-STING signaling pathway, thereby initiating pyroptosis. This activation was corroborated by elevated levels of pyroptosis-associated proteins, including cGAS, STING, NLRP3, caspase-1, Gasdermin D (GSDMD), cGAMP, IL-18, and IL-1β. Notably, the inhibition of NLRP3 effectively abolished the upregulation of IL-18, and IL-1β levels.

CONCLUSION

Radiation can improve cardiac function, decrease hypertrophy of myocardial cells, and induce oxidative stress. This oxidative stress results in the leakage of mitochondrial DNA (mtDNA), which subsequently activates the cGAS/STING/NLRP3 signalling pathway, culminating in pyroptosis.

Sinomenine alleviates neuroinflammation in chronic cerebral hypoperfusion by promoting M2 microglial polarization and inhibiting neuronal pyroptosis via exosomal miRNA-223-3p

Chronic cerebral hypoperfusion (CCH) is a major contributor to vascular dementia, with neuroinflammation playing a central role in its pathogenesis. Sinomenine (SINO), a natural alkaloid derived from traditional Chinese medicine, has shown significant anti-inflammatory and neuroprotective properties. However, its efficacy and mechanism of action in CCH remain unclear. In this study, we established a CCH rat model through bilateral common carotid artery occlusion and administered 10 mg/kg of SINO daily. Behavioral tests demonstrated that SINO significantly improved cognitive and memory functions in CCH rats. Histological analysis revealed that SINO effectively reduced neuroinflammation and damage in the hippocampal CA1, CA3, and DG regions. Mechanistically, SINO promoted microglial polarization from the M1 to M2 phenotype, markedly inhibiting the release of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α. Further exploration of its neuroprotective mechanism showed that exosomes from SINO-treated microglia were enriched with miRNA-223-3p, which suppressed NLRP3-mediated pyroptosis in neurons. While our findings highlight the therapeutic potential of SINO, further studies are needed to validate its safety and efficacy in diverse populations and chronic settings. In summary, this study not only demonstrates SINO's regulatory effect on microglial polarization in CCH but also unveils a novel neuroprotective mechanism through exosomal miRNA-223-3p delivery, providing a solid theoretical foundation for SINO's potential as a treatment for CCH.

Steroids combined with anticoagulant in acute/subacute severe cerebral venous thrombosis

BACKGROUND

Inflammation plays a critical role in severe cerebral venous thrombosis (CVT) pathogenesis, but the benefits of anti-inflammatory therapies remain unclear. This study aimed to investigate the association between steroid therapy combined with anticoagulation and the prognosis of acute/subacute severe CVT patients.

METHODS

A prospective cohort study enrolled patients with acute/subacute severe CVT at Xuanwu Hospital (July 2020-January 2024). Patients were allocated into steroid and non-steroid groups based on the treatment they received. Functional outcomes (modified Rankin scale [mRS]) were evaluated at admission, discharge, and 6 months after discharge. Serum high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), cerebrospinal fluid (CSF) IL-6, and intracranial pressure were measured at admission and discharge in the steroid group. Fundoscopic Frisén grades were assessed at admission and 6 months after discharge. Univariate and multivariate logistic regression were used to analyses were used to evaluated associations between steroid use and favorable outcomes (mRS ≤2) at the 6-month follow-up. Paired tests assessed changes in hs-CRP and other variables before and after treatment, and Spearman's correlations were used to analyzed relationships between these changes and functional improvements.

RESULTS

A total of 107 and 58 patients in the steroid and non-steroid groups, respectively, were included in the analysis. Compared with the non-steroid group, the steroid group had a higher likelihood of achieving an mRS score of 0-2 (93.5% vs. 82.5%, OR = 2.98, P = 0.037) at the 6-month follow-up. After adjusting for confounding factors, the result remained consistent. Pulsed steroid therapy did not increase mortality during hospitalization or follow-up, nor did it lead to severe steroid-related complications (all P >0.05). Patients in the steroid group showed a significant reduction in serum hs-CRP, IL-6, CSF IL-6, and intracranial pressure at discharge compared to at admission, as well as a significant reduction in the fundoscopic Frisén grade at the 6-month follow-up compare to at admission (all P <0.001). A reduction in serum inflammatory marker levels during hospitalization positively correlated with improvements in functional outcomes (P <0.05).

CONCLUSION

Short-term steroid use may be an effective and safe adjuvant therapy for acute/subacute severe CVT when used alongside standard anticoagulant treatments, which are likely due to suppression of the inflammatory response. However, these findings require further validation in randomized controlled trials.

TRAIL REGISTRATION

ClinicalTrials.gov, NCT05990894.

HCAR2 Modulates the Crosstalk between Mammary Epithelial Cells and Macrophages to Mitigate Staphylococcus aureus Infection in the Mouse Mammary Gland

Staphylococcus aureus (S. aureus) is a major zoonotic pathogen, with mammary gland infections contributing to mastitis, a condition that poses significant health risks to lactating women and adversely affects the dairy industry. Therefore, understanding the immune mechanisms underlying mammary infections caused by S. aureus is essential for developing targeted therapeutic strategies against mastitis. This study identified hydroxycarboxylic acid receptor 2 (HCAR2) as a potential regulator of S. aureus infection in mammary glands. It is demonstrated that HCAR2 deficiency exacerbates the inflammatory response and disrupts the blood-milk barrier in the mammary gland during S. aureus infection, with NLRP3 inflammasome-mediated pyroptosis playing a central role. Activation of HCAR2, on the other hand, suppressed CMPK2 expression, thereby mitigating mitochondrial damage and pyroptosis in mouse mammary epithelial cells (mMECs) induced by S. aureus. Additionally, mitochondrial DNA (mtDNA) released from S. aureus-infected mMECs activates the cGAS/STING signaling pathway in macrophages, impairing their bactericidal activity. In conclusion, this study highlights the critical role of HCAR2 in S. aureus infection of the mammary gland and provides a theoretical basis for identifying potential therapeutic targets for such infections.

The augment effects of magnesium hydride on the lipid lowering effect of atorvastatin: an in vivo and in vitro investigation

There is strong evidence connecting increased serum lipid levels to cardiovascular disorders, including atherosclerosis. Statins is prescribed as the primary medication to decrease lipid levels. Recent research has demonstrated that hydrogen possesses anti-inflammatory and antioxidant properties by modulating the expression of peroxisome proliferator-activated receptor gamma coactivator-1α, ultimately leading to the preservation of lipid homeostasis. Magnesium hydride (MgH2) is a prolonged stable hydrogen storage medium, which can be utilized to investigate its synergistic lipid-lowering effect with statins and its detailed molecular mechanism, both in vivo and in vitro. To ascertain the safety and efficacy of MgH2, we executed a comprehensive research of its influence on both physiological and pathological metrics. We noted a substantial diminution in lipid levels when MgH2 was integrated with atorvastatin, as attested by oil red staining. Furthermore, we scrutinized the regulatory effect of MgH2 on cytochrome P450 3A, which is a metabolic enzyme of statins, and discovered that it could be reduced by the MgH2. Concluding from our results, we propose that MgH2 inhibits the expression of cytochrome P450 3A in the liver and exerts an auxiliary lipid-lowering effect by increasing the blood concentration of statins. By augmenting our comprehension of MgH2's role in ameliorating lipid metabolism, we aspire to develop more promising therapies in the future.

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.

Escin Rescues Blood-brain Barrier and Inhibits NLRP3 Inflammasome-mediated Pyroptosis in Rats with Superior Sagital Sinus Thrombosis

Objective: The purpose of this study is to investigate the therapeutic value of escin and its potential mechanisms in rats with superior sagittal sinus thrombosis (SSST). Methods: The motor function of rats was assessed using the open field, balance beam, and rotarod tests following one week of escin treatment. Laser Speckle Contrast Imaging (LSCI) was used to evaluate the blood flow in the superior sagittal sinus. Evans blue staining was used to assess the permeability of blood-brain barrier. The protein expression levels of Occludin, ZO-1 and MMP-9 was analyzed by Western blotting to assess blood-brain barrier disruption. Iba1, CD68 and NLRP3 immunofluorescent staining was conducted to evaluate the activation of microglia and NLRP3 inflammasome. The protein expression levels of NLRP3, Caspase-1, IL-1β, IL-18 and GSDMD was analyzed by Western blotting to assess NLRP3 inflammasome activation and pyroptosis. Immunohistochemistry for NeuN was used to evaluate the neuronal pyroptosis. Results: Rats with SSST exhibited decreased movement distance, duration and latency to fall, as well as increased balance latency compared to sham rats, indicating its motor dysfunction. Escin treatment alleviated the motor dysfunction in rats with SSST. LSCI revealed a decrease in the blood flow in the superior sagittal sinus of rats with SSST. There was no discernible change in blood flow between SSST rats treated with escin and those not, suggesting that escin did not promote recanalization of the superior sagittal sinus. By decreasing Evans blue dye content and MMP-9 protein expression and increasing the protein expressions of Occludin and ZO-1, escin treatment improved blood-brain barrier (BBB) disruption and protected tight junction proteins. Escin also reduced the number of microglia-originated macrophage and the number of NLRP3-positive macrophage. Additionally, escin treatment down-regulated the protein expression levels of NLRP3, Caspase-1, IL-1β, IL-18, and GSDMD in the parasagittal cortex of SSST rats, suggesting its ability to inhibit NLRP3 inflammasome activation and therefore reduce pyroptosis. Finally, escin treatment significantly increased the neuronal survival in the parasagittal cortex of rats with SSST. Conclusions: Treatment with escin improved motor function not by recanalizing the SSS. Treatment with escin protected the blood-brain barrier, inhibited the microglia activation and suppressed the NLRP3 inflammasome-mediated pyroptosis in the parasagittal cortex of SSST rats, thereby playing an anti-pyroptosis and neuroprotective effect.

ncRNAs-Mediated Pyroptosis in Cerebral Ischemia-Reperfusion Injury: Pathophysiology, Mechanisms, and Therapeutic Perspectives

Cerebral ischemia-reperfusion injury (CIRI) is a complex pathological process triggered by transient obstruction of blood flow and subsequent reperfusion, ultimately leading to intracellular disturbances such as oxidative stress, inflammatory responses, and programmed cell death. Among the various types of cell death, pyroptosis (an inflammatory kind of regulated cell death) has received increasing attention due to its involvement in key neurovascular unit cells, including endothelial cells, neurons, microglia, and astrocytes. Intriguingly, accumulating evidence demonstrates that non-coding RNAs (ncRNAs), including long non-coding RNAs, microRNAs, and circular RNAs, can modulate multiple stages of pyroptosis in CIRI. This review synthesizes recent findings on the ncRNAs-regulated pyroptosis in CIRI. We highlight the molecular underpinnings of pyroptotic activation following ischemic injury and discuss how ncRNAs shape these mechanisms. By elucidating the interactions between ncRNAs and pyroptosis-related pathways, we intend to present innovative viewpoints for early diagnosis and the development of potential therapeutic strategies to mitigate CIRI.

Methamphetamine and HIV-1 Tat Synergistically Induce Microglial Pyroptosis Via Activation of the AIM2 Inflammasome

OBJECTIVE

Human immunodeficiency virus (HIV)-infected individuals who abuse methamphetamine (METH) exhibit more severe neurotoxicity and cognitive impairment. Pyroptosis, a programmed cell death pathway mediated by the inflammasome, has been implicated in various neurological diseases. This study aimed to elucidate the role of the AIM2 inflammasome in METH- and HIV-1 Tat-induced pyroptosis in human brain tissue and in vitro models.

METHODS

Postmortem brain tissue from HIV-infected individuals with a history of METH abuse was analyzed for pyroptosis markers and AIM2 inflammasome components using immunohistochemistry, immunofluorescence, and Western blotting. BV2 microglial cells were lentivirally transduced to knockdown AIM2 expression. DNA damage was assessed using Western blotting and the comet assay. Expression of pyroptosis-related proteins was evaluated by electron microscopy, Western blotting, and immunofluorescence. Cell viability was measured using the CCK8 assay.

RESULTS

Elevated levels of pyroptosis markers and AIM2 inflammasome components were observed in brain tissue from HIV-infected METH users. METH and Tat synergistically induced pyroptosis in BV2 cells in a time- and concentration-dependent manner, accompanied by DNA damage and activation of the AIM2 inflammasome. Knockdown of AIM2 significantly reduced the expression of pyroptosis-related proteins.

CONCLUSION

METH and HIV-1 Tat proteins synergistically induce microglial pyroptosis by activating the AIM2 inflammasome through dsDNA damage. These findings suggest that targeting the AIM2 inflammasome may be a promising therapeutic strategy for HIV-associated neurocognitive disorder (HAND).

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.

β-Hydroxybutyrate-induced mitochondrial DNA (mtDNA) release mediated innate inflammatory response in bovine mammary epithelial cells by inhibiting autophagy

BACKGROUND

In perinatal dairy cows, ketosis is a prevalent metabolic disorder that lowers milk output and performance. Mitochondrial dysfunction and chronic inflammation in mammary tissue are linked to elevated blood ketone levels, particularly β-hydroxybutyrate (BHB). Recent research has linked cytosolic mitochondrial DNA (mtDNA) with chronic aseptic inflammation by activating the cGAS-STING pathway during metabolic disorders, while autophagy activation effectively reverses this process. However, whether it is involved in mammary gland damage during ketosis is poorly understood. Therefore, this study aimed to explore the underlying mechanisms of mtDNA-induced inflammation under BHB stress and evaluate the potential therapeutic strategy of autophagy activation in mitigating this damage.

RESULTS

Our study found an increased cytoplasmic mtDNA abundance in mammary gland tissues of dairy cows with ketosis and bovine mammary epithelial cell line (MAC-T) subjected to BHB stress. Further investigations revealed the activation of the cGAS-STING pathway and inflammatory response, indicated by elevated levels of cGAS and STING, along with increased phosphorylation levels of TBK1, P65, and IκB, and higher transcript levels of pro-inflammatory factors (IL-1B, IL-6, and TNF-α) in both in vivo and in vitro experiments. Notably, STING inhibition via si-STING transfection reversed BHB-induced inflammation. Additionally, autophagy activation appeared to protect against BHB stress by facilitating the removal of cytoplasmic mtDNA and preventing cGAS-STING pathway-mediated inflammation.

CONCLUSIONS

The findings illustrate that elevated BHB levels lead to the release of cytoplasmic mtDNA, which in turn activates the cGAS-STING pathway and triggers an inflammatory response in the mammary glands during hyperketonemia. Conversely, autophagy activation has been shown to alleviate this process by promoting cytoplasmic mtDNA degradation.

ROS-regulated SUR1-TRPM4 drives persistent activation of NLRP3 inflammasome in microglia after whole-brain radiation

Delayed radiation-induced brain injury (RIBI) characterized by progressive cognitive decline significantly impacts patient outcomes after radiotherapy. The activation of NLRP3 inflammasome within microglia after brain radiation is involved in the progression of RIBI by mediating inflammatory responses. We have previously shown that sulfonylurea receptor 1-transient receptor potential M4 (SUR1-TRPM4) mediates microglial NLRP3-related inflammation following global brain ischemia. However, the role of SUR1-TRPM4 in RIBI remains unclear. Here, we found that whole-brain radiation induced up-regulation and assembly of SUR1-TRPM4, which further activated the NLRP3 inflammasome in microglia and caused persistent neuroinflammation in mice. Blocking SUR1-TRPM4 by glibenclamide or gene deletion of Trpm4 effectively prevented NLRP3-mediated neuroinflammation and alleviated RIBI. Utilizing the mouse model of RIBI and irradiated BV2 cells, we further demonstrated that irradiation caused mitochondrial damage to microglia, leading to violent release of reactive oxygen species (ROS), which enhanced the transcription of SUR1, TRPM4, and NLRP3 inflammasome-related molecules. Moreover, ROS up-regulated ten-eleven translocation 2 (TET2) to enhance TRPM4 expression by mediating the demethylation of the gene promoter, thereby facilitating the assembly of SUR1-TRPM4 in microglia. In summary, this study deciphers that SUR1-TRPM4 crucially mediates the persistent activation of microglial NLRP3 inflammasome under the action of ROS after whole-brain radiation, offering novel therapeutic strategies for delayed RIBI as well as other NLRP3-related neurological disorders involving excessive ROS production.

PPARα suppresses growth of hepatocellular carcinoma in a high-fat diet context by reducing neutrophil extracellular trap release

Background & Aims

The role of infiltrating neutrophils in hepatocellular carcinoma (HCC) is modulated by cellular metabolism, specifically lipid homeostasis. Throughout the progression of HCC, alterations in lipid metabolism are intricately linked with regulation of neutrophil function and the release of neutrophil extracellular traps (NETs). However, how much the protumor effect of a high-fat diet (HFD) depends on NETs and the potential interplay between NETs and other leukocytes in HCC remains uncertain.

Methods

In this study, the molecular mechanism of NET release and the potential beneficial effects of PPARα agonists on the HCC microenvironment were explored through proteomics, metabolomics, tissue microarray, immunofluorescence, flow cytometry, western blot, and dual-luciferase reporter gene assays (n = 6 per group).

Results

Our study demonstrated a notable inhibition of PPARα signaling in HCC. Furthermore, the disruption of PPARα-mediated lipid metabolism was responsible for the release of NETs. The presence of a HFD was observed to induce mitochondrial impairment in neutrophils, leading to the activation of cGAS-STING by oxidized mitochondrial DNA (Ox-mtDNA). Consequently, this activation triggered the release of NETs containing Ox-mtDNA through the enhancement of NLRP3-GSDMD-N in a NF-κB-dependent manner. Moreover, the release of NETs within HCC tissues effectively isolated cytotoxic leukocytes in the outer regions of HCC.

Conclusions

Our study not only provides insight into the relationship between lipid metabolism disorders and NETs' tumor-promoting function, but also provides an important strategic reference for multi-target or combined immunotherapy of HCC.

Impact and implications

We have identified PPARα and its agonists as therapeutic targets for controlling the neutrophil extracellular traps associated with high lipid metabolism. Results from preclinical models suggest that PPARα can limit mitochondrial oxidative stress, inhibit cGAS-STING-NF-κB signaling, and limit the release of neutrophil extracellular traps, thereby increasing the contact of anti-tumor leukocytes and hepatocellular cancer cells and limiting tumor growth.

Mitochondrial DNA from endothelial cells activated the cGAS-STING pathway and regulated pyroptosis in lung ischaemia reperfusion injury after lung transplantation

OBJECTIVE

Cell dysfunction and death induced by lung ischaemia-reperfusion injury (LIRI) are the main causes of death in transplant patients. Activation of the cGAS-STING-induced immune response and death plays a critical role in multiple organ injuries. However, no study has yet investigated the role of the cGAS-STING pathway in LIRI after lung transplantation.

METHODS

Sprague-Dawley (SD) rats were subjected to left lung transplantation and administered inhibitors of cGAS and STING. The expression of cGAS-STING-TBK1-IRF3, histological injury, pulmonary permeability, and the levels of cytokines and pyroptotic proteins in transplanted lungs were tested. Endothelial cells were subjected to hypoxemia and reoxygenation and treated with inhibitors of cGAS and STING. Mitochondrial DNA (mtDNA), the cGAS-STING axis and cytokine levels in cells, cellular activity and death were evaluated. Moreover, after the administration of deoxyribonuclease (DNase) I, the reoxygenated endothelial cells were also examined for cellular function and inflammatory factor expression. Finally, we administered an agonist of STING and an inhibitor of cathepsin B to the normal endothelium and investigated pyroptosis and pyroptotic proteins.

RESULTS

After 24 h of reperfusion, the expression of cGAS-STING-TBK1-IRF3 and pyroptotic proteins was significantly increased, and inhibitors of cGAS or STING ameliorated lung injury and reduced pyroptotic protein levels. In vitro, the inhibition of cGAS and STING reduced the activation of TBK and IRF3 and reduced cellular injury and death. The activation of cGAS-STING and cellular inflammation were suppressed by DNase I. Cathepsin B and NLRP3 were upregulated by an agonist of STING, and an inhibitor of cathepsin B reduced NLRP3 levels.

CONCLUSION

cGAS-STING participated in LIRI by promoting endothelial cell pyroptosis via cathepsin B.

Unmasking hidden risks: cerebral venous sinus thrombosis and spontaneous subdural hematoma in women on oral contraceptives - insights from a case report and systematic literature review

BACKGROUND AND OBJECTIVE

Cerebral venous thrombosis (CVT) is a rare but critical condition, particularly in young women, often linked to oral contraceptive use. It can lead to complications like subdural hematoma (SH), which are challenging to diagnose and manage. We report the case of a 39-year-old woman who presented with severe headaches and neurological symptoms, leading to a diagnosis of chronic SH and CVT, associated with long-term oral contraceptive use. This case is unique as it documents the first known instance of chronic SH associated with CVT induced by oral contraceptives. Our objective was to explore this association using the Bradford Hill criteria and to review the diagnostic and therapeutic challenges of CVT and SH in this population.

METHODS

We conducted a systematic literature review adhering to PRISMA guidelines, focusing on SH cases linked to CVT in women using oral contraceptives.

RESULTS

Including our case, four cases of SH associated with CVT secondary to oral contraceptive use were identified. Common symptoms included severe headache and neurological deficits. All patients received anticoagulation therapy, with surgical intervention required in severe cases. Prognosis was generally favorable with appropriate management.

CONCLUSION

This case emphasizes the importance of considering CVT in women presenting with spontaneous SH, particularly those on oral contraceptives. Early diagnosis, careful clinical and radiological monitoring, and timely surgical intervention are crucial for optimal outcomes.

An excitatory neural circuit for descending inhibition of itch processing

Itch serves as a self-protection mechanism against harmful external agents, whereas uncontrolled and persistent itch severely influences the quality of life of patients and aggravates their diseases. Unfortunately, the existing treatments are largely ineffective. The current difficulty in treatment may be closely related to the fact that the central neural mechanisms underlying itch processing, especially descending inhibition of itch, are poorly understood. Here, we demonstrate that an excitatory descending neural circuit from rostral anterior cingulate cortex pyramidal (rACCPy) neurons to periaqueductal gray GABAergic (PAGGABA) neurons plays a key role in the inhibition of itch. The activity of itch-tagged rACCPy neurons decreases during the itch-evoked scratching period. Artificial activation or inhibition of the neural circuits significantly impairs or enhances itch processing, respectively. Thus, an excitatory neural circuit is identified as playing a crucial inhibitory role in descending regulation of itch, suggesting that it could be a potential target for treating itch.

Neuroprotection of celastrol against postoperative cognitive dysfunction through dampening cGAS-STING signaling

Neuroinflammation is a central player in postoperative cognitive dysfunction (POCD), an intractable and highly confounding neurological complication with finite therapeutic options. Celastrol, a quinone methide triterpenoid, is a bioactive ingredient extracted from Tripterygium wilfordii with talented anti-inflammatory capacity. However, it is unclear whether celastrol can prevent anesthesia/surgery-evoked cognitive deficits in an inflammation-specific manner. The STING agonist 5,6-dimethylxanthenone-4-acetic acid (DMXAA) was used to determine whether celastrol possesses neuroprotection dependent on the STING pathway in vivo and in vitro. Isoflurane and laparotomy triggered cGAS-STING activation, caspase-3/GSDME-dependent pyroptosis, and enhanced Iba-1 immunoreactivity. Celastrol improved cognitive performance and decreased the levels of cGAS, 2'3'-cGAMP, STING, NF-κB phosphorylation, Iba-1, TNF-α, IL-6, and IFN-β. Downregulation of cleaved caspase-3 and N-GSDME was observed in the hippocampus of POCD mice and HT22 cells after celastrol administration, accompanied by limited secretion of pyroptosis-pertinent pro-inflammatory cytokines IL-1β and IL-18. DMXAA neutralized the favorable influences of celastrol on cognitive function, as confirmed by the activation of the STING/caspase-3/GSDME axis. These findings implicate celastrol as a therapeutic agent for POCD through anti-inflammation and anti-pyroptosis.

Association of Serum Uric Acid to Lymphocyte Ratio with Clinical Outcomes in Cerebral Venous Sinus Thrombosis

Purpose

The serum uric acid to lymphocyte ratio (ULR) is a systemic marker of inflammation, and it has been studied as an indicator of prognosis in cardiovascular disease. This study investigates the relationship between ULR and clinical outcomes in patients with cerebral venous sinus thrombosis (CVST).

Patients and Methods

A total of 636 patients with CVST were included in the study and randomly divided into a training set (n = 445) and a testing set (n = 119) in a ratio of 7:3.Logistic regression analysis was employed to analyze the risk factors for poor outcomes. The nomogram was established using the training dataset, and its predictive performance was assessed with the testing dataset.

Results

ULR accurately predicted poor outcomes in CVST and was linked to a higher likelihood of poor outcomes (OR=1.015, 95% CI: 1.003-1.026, P = 0.013). Age, infection, intracranial hypertension, coma, and intracerebral hemorrhage were independent predictors of poor outcomes in CVST. Additionally, a new nomogram incorporating ULR was constructed to predict the risk of poor outcomes in CVST patients. The nomogram demonstrated good accuracy and reliability, as shown by the receiver operating characteristic curve, calibration curve, and decision curve analysis.

Conclusion

ULR independently forecasted poor outcomes in patients with CVST. The novel nomogram incorporating ULR could provide CVST patients with personalized risk assessment and treatment plans, leading to improved patient prognosis.

PROTAC based STING degrader attenuates acute colitis by inhibiting macrophage M1 polarization and intestinal epithelial cells pyroptosis mediated by STING-NLRP3 axis

Inflammatory bowel diseases (IBDs) are chronic, relapsing, and inflammatory disorders of the gastrointestinal tract characterized by abnormal immune responses. Recently, STING has emerged as a promising therapeutic target for various autoinflammatory diseases. However, few STING-selective small molecules have been investigated as novel strategies for IBD. In this study, we sought to examine the effects of PROTAC-based STING degrader SP23 on acute colitis and explore its underlying mechanism. SP23 treatment notably alleviates dextran sulfate sodium (DSS)-induced colitis. Pharmacological degradation of STING significantly reduced the production of inflammatory cytokines, such as TNF-α, IL-1β, and IL-6, and inhibited macrophage polarization towards the M1 type. Furthermore, SP23 administration decreased the loss of tight junction proteins, including ZO-1, occludin, and claudin-1, and downregulated STING and NLRP3 signaling pathways in intestinal inflammation. In vitro, STING activated NLRP3 inflammasome-mediated pyroptosis in intestinal epithelial cells, which could be abrogated by SP23 and STING siRNA intervention. In conclusion, these findings provide new evidence for STING as a novel therapeutic target for IBD, and reveal that hyperactivation of STING could exaggerate colitis by inducing NLRP3/Caspase-1/GSDMD axis mediated intestinal epithelial cells pyroptosis.

Interleukin-6 deficiency reduces neuroinflammation by inhibiting the STAT3-cGAS-STING pathway in Alzheimer's disease mice

BACKGROUND

The Interleukin-6 (IL-6)-signal transducer and activator of transcription 3 (STAT3) pathway, along with the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, are critical contributors to neuroinflammation in Alzheimer's disease (AD). Although previous research outside the context of AD has indicated that the IL-6-STAT3 pathway may regulate the cGAS-STING pathway, the exact molecular mechanisms through which IL-6-STAT3 influences cGAS-STING in AD are still not well understood.

METHODS

The activation of the IL-6-STAT3 and cGAS-STING pathways in the hippocampus of 5×FAD and WT mice was analyzed using WB and qRT-PCR. To explore the effects of IL-6 deficiency, Il6+/- mice were crossed with 5×FAD mice, and the subsequent impact on hippocampal STAT3 pathway activity, cGAS-STING pathway activation, amyloid pathology, neuroinflammation, and cognitive function was evaluated through WB, qRT-PCR, immunohistochemistry, ThS staining, ELISA, and behavioral tests. The regulatory role of STAT3 in the transcription of the Cgas and Sting genes was further validated using ChIP-seq and ChIP-qPCR on hippocampal tissue from 5×FAD and Il6-/-: 5×FAD mice. Additionally, in the BV2 microglial cell line, the impact of STAT3 activation on the transcriptional regulation of Cgas and Sting genes, as well as the production of inflammatory mediators, was examined through WB and qRT-PCR.

RESULTS

We observed marked activation of the IL-6-STAT3 and cGAS-STING pathways in the hippocampus of AD mice, which was attenuated in the absence of IL-6. IL-6 deficiency reduced beta-amyloid deposition and neuroinflammation in the hippocampus of AD mice, contributing to cognitive improvements. Further analysis revealed that STAT3 directly regulates the transcription of both the Cgas and Sting genes. These findings suggest a potential mechanism involving the STAT3-cGAS-STING pathway, wherein IL-6 deficiency mitigates neuroinflammation in AD mice by modulating this pathway.

CONCLUSION

These findings indicate that the STAT3-cGAS-STING pathway is critical in mediating neuroinflammation associated with AD and may represent a potential therapeutic target for modulating this inflammatory process in AD.

The cGAS-STING pathway drives neuroinflammation and neurodegeneration via cellular and molecular mechanisms in neurodegenerative diseases

Neurodegenerative diseases (NDs) are a type of common chronic progressive disorders characterized by progressive damage to specific cell populations in the nervous system, ultimately leading to disability or death. Effective treatments for these diseases are still lacking, due to a limited understanding of their pathogeneses, which involve multiple cellular and molecular pathways. The triggering of an immune response is a common feature in neurodegenerative disorders. A critical challenge is the intricate interplay between neuroinflammation, neurodegeneration, and immune responses, which are not yet fully characterized. In recent years, the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon gene (STING) pathway, a crucial immune response for intracellular DNA sensing, has gradually gained attention. However, the specific roles of this pathway within cellular types such as immune cells, glial and neuronal cells, and its contribution to ND pathogenesis, remain not fully elucidated. In this review, we systematically explore how the cGAS-STING signaling links various cell types with related cellular effector pathways under the context of NDs for multifaceted therapeutic directions. We emphasize the discovery of condition-dependent cellular heterogeneity in the cGAS-STING pathway, which is integral for understanding the diverse cellular responses and potential therapeutic targets. Additionally, we review the pathogenic role of cGAS-STING activation in Parkinson's disease, ataxia-telangiectasia, and amyotrophic lateral sclerosis. We focus on the complex bidirectional roles of the cGAS-STING pathway in Alzheimer's disease, Huntington's disease, and multiple sclerosis, revealing their double-edged nature in disease progression. The objective of this review is to elucidate the pivotal role of the cGAS-STING pathway in ND pathogenesis and catalyze new insights for facilitating the development of novel therapeutic strategies.

Innate immunity-mediated neuroinflammation promotes the onset and progression of post-stroke depression

Post-stroke depression (PSD) is a prevalent psychiatric disorder after stroke, with the incidence of approximately one-third among stroke survivors. It is classified as an organic mental disorder and has a well-documented association with stroke affecting various aspects of patients, such as the recovery of limb motor function, daily living self-care ability, and increasing the mortality of stroke survivors. However, the pathogenesis of PSD is not yet fully understood. Currently, immune inflammation is a research hotspot. This review focuses on the pathogenesis of PSD, particularly elucidating the role of inflammation in mediating neuroinflammation through innate immunity. Simultaneously, we highlight that peripheral inflammation following a stroke may trigger a detrimental cycle of neuroinflammation by activating innate immune pathways within the central nervous system, which could potentially contribute to the development of PSD. Lastly, we summarize potential treatments for PSD and propose targeting cytokines and innate immune pathways as novel therapeutic approaches.

Steroids' Neuroprotective Potential in Severe Cerebral Venous Thrombosis: Experimental and Clinical Exploration of NLRP3 Inflammasome Inhibition

BACKGROUND

NLRP3 inflammasome-related inflammation might play an important role in the pathophysiology of severe CVT. The use of steroids as anti-inflammatory agents in improving severe CVT prognosis remains controversial.

METHODS

A total of 94 male Sprague-Dawley rats were used. We evaluated the dynamic and association between NLRP3 inflammasome in brain, blood, and CSF and severity in severe CVT rats and/or patients. We also explored the effect of steroids on NLRP3 activation, neurological injury, and CSF circulation disturbance after CVT in animals and/or patients.

RESULTS

In rats, compared with the sham group, NLRP3-related factors rose on day 1, peaked on day 2 (NLRP3, Sham: 0.79 ± 0.22; day 2: 1.25 ± 0.08, p < 0.01; pro-Caspase-1, Sham: 0.58 ± 0.13, day 2: 1.20 ± 0.44, p < 0.05; GSDMD, Sham: 0.94 ± 0.22, day 2: 1.72 ± 0.46, p < 0.05; pro-IL-1β, Sham: 0.74 ± 0.15, day 2: 1.35 ± 0.09, p < 0.01), decreased on day 7 in rats (n = 4 per group). Thrombus (Sham: 0.00 ± 0.00, day 2: 3.44 ± 0.70, p < 0.0001), infarct size (Sham: 0.00 ± 0.00, day 2: 11.99 ± 6.26, p < 0.01) and neurological deficits appeared similar trend. In 50 patients, serum NLRP3 and IL-6 levels correlated positively with NIHSS (r = 0.4273, p = 0.0020; r = 0.4938, p = 0.0029) and mRS (r = 0.5349, p = 0.0125; r = 0.6213, p = 0.026), while CSF IL-6 correlated positively with mRS on admission (r = 0.5349, p = 0.0125). Compared with baseline, NLRP3 (0.36 (0.36, 0.36) vs. 0.41 (0.37, 0.84), p < 0.0001) and IL-6 decreased (4.06 ± 1.48 vs. 12.03 ± 7.80, p < 0.05), accompanying by improvement of neurological deficits and CSF circulation (all p < 0.01) after steroids therapy in severe CVT patients at discharge and 3 months follow-up. No significant steroid-related adverse effects were observed.

CONCLUSION

Short-term steroid therapy may improve prognosis of severe CVT by suppressing NLRP3 inflammasome-related inflammation.

Review of Excessive Cytosolic DNA and Its Role in AIM2 and cGAS-STING Mediated Psoriasis Development

In psoriasis, keratinocytes are triggered by factors, such as infection or tissue damage, to release DNA, which thereby activates plasmacytoid dendritic cells and macrophages to induce inflammation, thickened epidermis, and parakeratosis. The recognition of double-stranded (ds)DNA facilitates the activation of cytoplasmic DNA sensors absent in melanoma 2 (AIM2) inflammasome assembly and cyclic guanosine monophosphate adenosine monophosphate (cGAMP) synthase (cGAS) - stimulator of interferon gene (STING) pathway, both of which play a pivotal role in mediating the inflammatory response and driving the progression of psoriasis. Additionally, secreted proinflammatory cytokines can stimulate further DNA release from keratinocytes. Notably, the activation of AIM2 and cGAS-STING signaling pathways also mediates programmed cell death, potentially enhancing DNA overproduction. As a result, excessive DNA can activate these pathways, amplifying persistent inflammatory responses that contribute to the maintenance of psoriasis. Several studies have validated that targeting DNA and its mediated activation of AIM2 and cGAS-STING offers promising therapeutic strategies for psoriasis. Here, we postulate a hypothesis that excessive cytosolic DNA can activate AIM2 and cGAS-STING, mediating inflammation and programmed cell death, ultimately fostering DNA accumulation and contributing to the development of psoriasis.

Copper induced cytosolic escape of mitochondrial DNA and activation of cGAS-STING-NLRP3 pathway-dependent pyroptosis in C8-D1A cells

Copper, a vital mineral nutrient, possesses redox qualities that make it both beneficial and toxic to organisms. Excessive environmental copper exposure can result in neurological damage and cognitive decline in humans. Astrocytes, the predominant glial cells in the brain, are particularly vulnerable to pollutants, but the mechanism of copper-induced damage to astrocytes remains elusive. The aim of this study was to determine the role of the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway in initiating NLRP3 inflammasome-induced astrocyte pyroptosis and chronic inflammation under conditions of copper overload. Our findings indicated that copper exposure elevated mitochondrial ROS (mtROS) levels, resulting in mitochondrial damage in astrocytes. This damage caused the release of mitochondrial DNA (mtDNA) into the cytoplasm, which subsequently activated the cGAS-STING pathway. This activation resulted in interactions between STING and NLRP3 proteins, facilitating the assembly of the NLRP3 inflammasome and inducing pyroptosis. Furthermore, depletion of mtROS mitigated copper-induced mitochondrial damage in astrocytes and reduced mtDNA leakage. Pharmacological inhibition of STING or STING transfection further reversed copper-induced pyroptosis and the inflammatory response. In conclusion, this study demonstrated that the leakage of mtDNA into the cytoplasm and the subsequent activation of the cGAS-STING-NLRP3 pathway may be potential mechanisms underlying copper-induced pyroptosis in astrocytes. These findings provided new insights into the toxicity of copper.

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.

The role of cGAS-STING signaling in rheumatoid arthritis: from pathogenesis to therapeutic targets

Rheumatoid arthritis (RA) is a systemic autoimmune disease primarily characterized by erosive and symmetric polyarthritis. As a pivotal axis in the regulation of type I interferon (IFN-I) and innate immunity, the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) signaling pathway has been implicated in the pathogenesis of RA. This pathway mainly functions by regulating cell survival, pyroptosis, migration, and invasion. Therefore, understanding the sources of cell-free DNA and the mechanisms underlying the activation and regulation of cGAS-STING signaling in RA offers a promising avenue for targeted therapies. Early detection and interventions targeting the cGAS-STING signaling are important for reducing the medical burden on individuals and healthcare systems. Herein, we review the existing literature pertaining to the role of cGAS-STING signaling in RA, and discuss current applications and future directions for targeting the cGAS-STING signaling in RA treatments.

Inactivation of cGAS signaling pathway mediated by TDP-43 deficiency protects microglia from hypoxia/reoxygenation induced injury

BACKGROUND

Microglia are damaged during cerebral ischemia-reperfusion (I/R). This study was performed to investigate the regulatory effect of tAR DNA-binding protein-43 (TDP-43) on microglia after cerebral I/R in vitro and in vivo.

METHOD

The hypoxia/reoxygenation (H/R) treated microglia and rats with middle cerebral artery occlusion surgery were constructed respectively. The TDP-43 expression in brain tissues and microglia of each group was evaluated by qPCR and western blotting methods. Cell viability and cell apoptosis were combined to evaluate the degree of cell injury. As for animal experiments, neurological score and infarct volume were obtained to evaluate neurological injury.

RESULTS

The levels of TDP-43 in the brain tissues of I/R group were higher than that in sham group. Both TDP-43 and Iba1, a typical microglia marker, were expressed in the brain tissues. TDP-43 was also elevated in microglia with H/R treatment. Inhibition of TDP-43 significantly down-regulated neurological deficit scores of rats after I/R surgery, and weakened the H/R treatment induced injury by promoting cell viability, inhibiting cell apoptosis, down-regulating IL-6 and iNOS levels, and up-regulating Arg-1 and IL-10 levels. Inactivation of cGAS pathway mediated by TDP-43 knockdown protects microglia from H/R treatment induced injury.

CONCLUSION

The highly expressed TDP-43 level is associated with cerebral I/R, and inhibition of TDP-43 protects microglia from H/R induced injury through cGAS pathway in vitro and in vivo.

The dual role of microglia in intracerebral hemorrhage

Intracerebral hemorrhage has the characteristics of high morbidity, disability and mortality, which has caused a heavy burden to families and society. Microglia are resident immune cells in the central nervous system, and their activation plays a dual role in tissue damage after intracerebral hemorrhage. The damage in cerebral hemorrhage is embodied in the following aspects: releasing inflammatory factors and inflammatory mediators, triggering programmed cell death, producing glutamate induced excitotoxicity, and destroying blood-brain barrier; The protective effect is reflected in the phagocytosis and clearance of harmful substances by microglia, and the secretion of anti-inflammatory and neurotrophic factors. This article summarizes the function of microglia and its dual regulatory mechanism in intracerebral hemorrhage. In the future, drugs, acupuncture and other clinical treatments can be used to intervene in the activation state of microglia, so as to reduce the harm of microglia.

Pharmacological inhibition of cGAS ameliorates postoperative cognitive dysfunction by suppressing caspase-3/GSDME-dependent pyroptosis

Neuroinflammation is a major driver of postoperative cognitive dysfunction (POCD). The cyclic GMP-AMP synthase-stimulator of interferon gene (cGAS-STING) signaling is a prominent alarming device for aberrant double-stranded DNA (dsDNA) that has emerged as a key mediator of neuroinflammation in cognitive-related diseases. However, the role of the cGAS-STING pathway in the pathogenesis of POCD remains unclear. A POCD model was developed in male C57BL/6J mice by laparotomy under isoflurane (Iso) anesthesia. The cGAS inhibitor RU.521 and caspase-3 agonist Raptinal were delivered by intraperitoneal administration. BV2 cells were exposed to Iso and lipopolysaccharide (LPS) in the absence or presence of RU.521, and then cocultured with HT22 cells in the absence or presence of Raptinal. Cognitive function was assessed using the Morris water maze test and novel object recognition test. Immunofluorescence assays were used to observe the colocalization of dsDNA and cGAS. The downstream proteins and pro-inflammatory cytokines were detected using the Western blot and enzyme-linked immunosorbent assay (ELISA). Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining was used to assess the degree of cell death in the hippocampus following anesthesia/surgery treatment. Isoflurane/laparotomy and Iso + LPS significantly augmented the levels of cGAS in the hippocampus and BV2 cells, accompanied by mislocalized dsDNA accumulation in the cytoplasm. RU.521 alleviated cognitive impairment, diminished the levels of 2'3'-cGAMP, cGAS, STING, phosphorylated NF-κB p65 and NF-κB-pertinent pro-inflammatory cytokines (TNFα and IL-6), and repressed pyroptosis-associated elements containing cleaved caspase-3, N-GSDME, IL-1β and IL-18. These phenotypes could be rescued by Raptinal in vivo and in vitro. These findings suggest that pharmacological inhibition of cGAS mitigates neuroinflammatory burden of POCD by dampening caspase-3/GSDME-dependent pyroptosis, providing a potential therapeutic strategy for POCD.

Pharmacological inhibition of STING reduces neuroinflammation-mediated damage post-traumatic brain injury

BACKGROUND AND PURPOSE

Traumatic brain injury (TBI) remains a major public health concern worldwide with unmet effective treatment. Stimulator of interferon genes (STING) and its downstream type-I interferon (IFN) signalling are now appreciated to be involved in TBI pathogenesis. Compelling evidence have shown that STING and type-I IFNs are key in mediating the detrimental neuroinflammatory response after TBI. Therefore, pharmacological inhibition of STING presents a viable therapeutic opportunity in combating the detrimental neuroinflammatory response after TBI.

EXPERIMENTAL APPROACH

This study investigated the neuroprotective effects of the small-molecule STING inhibitor n-(4-iodophenyl)-5-nitrofuran-2-carboxamide (C-176) in the controlled cortical impact mouse model of TBI in 10- to 12-week-old male mice. Thirty minutes post-controlled cortical impact surgery, a single 750-nmol dose of C-176 or saline (vehicle) was administered intravenously. Analysis was conducted 2 h and 24 h post-TBI.

KEY RESULTS

Mice administered C-176 had significantly smaller cortical lesion area when compared to vehicle-treated mice 24 h post-TBI. Quantitative temporal gait analysis conducted using DigiGait™ showed C-176 administration attenuated TBI-induced impairments in gait symmetry, stride frequency and forelimb stance width. C-176-treated mice displayed a significant reduction in striatal gene expression of pro-inflammatory cytokines Tnf-α, Il-1β and Cxcl10 compared to their vehicle-treated counterparts 2 h post-TBI.

CONCLUSION AND IMPLICATIONS

This study demonstrates the neuroprotective activity of C-176 in ameliorating acute neuroinflammation and preventing white matter neurodegeneration post-TBI. This study highlights the therapeutic potential of small-molecule inhibitors targeting STING for the treatment of trauma-induced inflammation and neuroprotective potential.

Identification of a Hippocampus-to-Zona Incerta Projection involved in Motor Learning

Motor learning (ML), which plays a fundamental role in growth and physical rehabilitation, involves different stages of learning and memory processes through different brain regions. However, the neural mechanisms that underlie ML are not sufficiently understood. Here, a previously unreported neuronal projection from the dorsal hippocampus (dHPC) to the zona incerta (ZI) involved in the regulation of ML behaviors is identified. Using recombinant adeno-associated virus, the projections to the ZI are surprisingly identified as originating from the dorsal dentate gyrus (DG) and CA1 subregions of the dHPC. Furthermore, projection-specific chemogenetic and optogenetic manipulation reveals that the projections from the dorsal CA1 to the ZI play key roles in the acquisition and consolidation of ML behaviors, whereas the projections from the dorsal DG to the ZI mediate the retrieval/retention of ML behaviors. The results reveal new projections from the dorsal DG and dorsal CA1 to the ZI involved in the regulation of ML and provide insight into the stages over which this regulation occurs.

Inhibition of cGAS attenuates neonatal hypoxic-ischemic encephalopathy via regulating microglia polarization and pyroptosis

Background

Neonatal hypoxic-ischemic encephalopathy (HIE) is a condition causing brain injury in newborns with unclear pathogenesis. Cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) signaling pathway and NOD-like receptor protein 3 (NLRP3) mediated pyroptosis are thought to be involved in the pathological process of HIE, but whether these two mechanisms act independently is still unknown. Therefore, we aim to clarify whether there is any interaction between these two pathways and thus synergistically affects the progression of HIE.

Methods

The HIE model of neonatal rats was established using the Rice-Vannucci method. The potential therapeutic effect of RU.521 targeting cGAS on HIE was explored through rescue experiment. Twenty-four hours after modeling was selected as observation point, sham + vehicle group, HIE + vehicle group and HIE + RU.521 group were established. A complete medium of BV2 cells was adjusted to a glucose-free medium, and the oxygen-glucose deprivation model was established after continuous hypoxia for 4 hours and reoxygenation for 12 to 24 hours. 2,3,5-triphenyl tetrazolium chloride staining was employed to detect ischemic cerebral infarction in rat brain tissue, and hematoxylin and eosin staining was used to observe tissue injury. Immunofluorescence was applied to monitor the expression of cGAS. Real-time quantitative polymerase chain reaction and western blot were utilized to detect the expression of messenger RNA and protein.

Results

cGAS expression was increased in brain tissues of neonatal rats with HIE, and mainly localized in microglia. RU.521 administration reduced infarct size and pathological damage in rat HIE. Moreover, blocking cGAS with RU.521 significantly reduced inflammatory conditions in the brain by down-regulating STING expression, decreasing NLRP3 inflammasome activation and reducing microglial pyroptosis both in vivo and in vitro. Besides, RU.521 promoted the switching of BV2 cells towards the M2 phenotype.

Conclusions

This study revealed a link between the cGAS/STING pathway and the NLRP3/GSDMD/pyroptosis pathway in neonatal HIE. Furthermore, the small molecule compound RU.521 can negatively regulate cGAS/STING/NLRP3/pyroptosis axis and promote M2 polarization in microglia, which provides a potential therapeutic strategy for the treatment of neuroinflammation in HIE.