Agmatine Alleviates Epileptic Seizures and Hippocampal Neuronal Damage by Inhibiting Gasdermin D-Mediated Pyroptosis

Activity-based chemical proteomics reveals caffeic acid ameliorates pentylenetetrazol-induced seizures by covalently targeting aconitate decarboxylase 1

BACKGROUND

Epilepsy is a neurological disorder characterized by recurrent seizures, tightly associated with neuroinflammation. Activation of inflammatory cells and molecules in damaged nervous tissues plays a pivotal role in epilepsy. Caffeic acid, one of the most abundant polyphenols in coffee, has shown potent protective effects as a phytomedicine in various neurological disorders. However, the direct protein targets and exact molecular mechanisms of caffeic acid in epilepsy, remain largely elusive.

PURPOSE

This study aimed to explore the protective effects of caffeic acid in epilepsy and elucidate its underlying mechanism.

METHODS

In this study, we established pentylenetetrazol-induced acute and kindling models of seizures. Additionally, a BV2 microglial cellular inflammation model was established by lipopolysaccharide stimulation. The potential direct protein targets of caffeic acid in BV2 cells were analyzed using an activity-based protein profiling (ABPP) with a caffeic acid probe. Various methods such as pull-down assay, immunofluorescence and cellular heat transfer assays were used for experimental validation. The anti-inflammatory effects of caffeic acid in LPS-activated BV2 cells was proved by knocking down the target protein.

RESULTS

Here, we found that caffeic acid exhibits antiepileptic effects in pentylenetetrazol-induced epilepsy mice and exerts anti-neuroinflammation effect in vivo and in vitro. Besides, we discovered that caffeic acid directly binds to aconitate decarboxylase 1 and influenced its enzymatic activity. Moreover, we indicated that caffeic acid exhibits anti-neuroinflammation effect through aconitate decarboxylase 1 mediated PERK-NF-κB pathway in vitro.

CONCLUSION

In summary, this study elucidates, for the first time, the potential antiepileptic targets and mechanism of action of caffeic acid using the ABPP strategy. Our study provides evidence supporting the utilization of caffeic acid as a promising therapeutic agent for treating epilepsy and neuroinflammation-related disorders.

Effects of Baicalein Pretreatment on the NLRP3/GSDMD Pyroptosis Pathway and Neuronal Injury in Pilocarpine-Induced Status Epilepticus in the Mice

Status epilepticus (SE) links to high mortality and morbidity. Considering the neuroprotective property of baicalein (BA), we investigated its effects on post-SE neuronal injury via the NLRP3/GSDMD pathway. Mice were subjected to SE modeling and BA interference, with seizure severity and learning and memory abilities evaluated. The histological changes, neurological injury and neuron-specific enolase (NSE)-positive cell number in hippocampal CA1 region, and cell death were assessed. Levels of the NOD-, LRR-, and pyrin domain-containing 3 (NLRP3)/gasdermin-D (GSDMD) pathway-related proteins, inflammatory factors, and Iba-1 + NLRP3+ and Iba-1 + GSDMD-N+ cells were determined. BA ameliorated post-SE cognitive dysfunction and neuronal injury in mice, as evidenced by shortened escape latency, increased number of crossing the target quadrant within 60 s and the time staying in the target quadrant, alleviated hippocampal damage, increased viable cell number, decreased neuronal injury, and increased NSE-positive cells. Mechanistically, BA repressed microglial pyroptosis, reduced inflammatory factor release, and attenuated neuronal injury by inhibiting the NLRP3/GSDMD pathway. The NLRP3 inhibitor exerted similar effects as BA on SE mice, while the NLRP3 activator partially reversed BA-improved post-SE neuronal injury in mice. Conjointly, BA reduced microglial pyroptosis in hippocampal CA1 area by inhibiting the NLRP3/GSDMD pyroptosis pathway, thereby ameliorating post-SE neuronal injury in mice.

Agmatine suppresses glycolysis via the PI3K/Akt/mTOR/HIF-1α signaling pathway and improves mitochondrial function in microglia exposed to lipopolysaccharide

Modulating metabolic pathways in activated microglia can alter their phenotype, which is relevant in uncontrolled neuroinflammation as a component of various neurodegenerative diseases. Here, we investigated how pretreatment with agmatine, an endogenous polyamine, affects metabolic changes in an in vitro model of neuroinflammation, a murine microglial BV-2 cell line exposed to lipopolysaccharide (LPS). Hence, we analyzed gene expression using qPCR and protein levels using Western blot and ELISA. Microglial metabolic status was assessed by measuring lactate release and cellular ATP by enzymatic and luminescence spectrophotometry. Mitochondrial functionality was analyzed by fluorescent probes detecting mitochondrial membrane potential (mtMP) and superoxide production. Our findings suggest that kinase pathways associated with hypoxia-inducible factor-1α (HIF-1α) regulate energy metabolism in pro-inflammatory activated microglia. We have shown that LPS induces HIF-1α and genes for glucose transporter and glycolytic rate, increases lactate production and causes mitochondrial dysfunction, suggesting a metabolic shift towards glycolysis. Agmatine inhibits the PI3K/Akt pathway and negatively regulates mammalian target of rapamycin (mTOR) phosphorylation and HIF-1α levels, reducing lactate and tumor necrosis factor (TNF) production, which is supported by pharmacological blockade of PI3K. Pretreatment with agmatine also rescues mitochondrial function by counteracting the LPS-induced decline in mtMP and increase in mitochondrial superoxide, resulting in an anti-apoptotic effect. Agmatine alone increases intracellular ATP levels and maintains this effect even under pro-inflammatory conditions. Our study emphasizes the ability of agmatine to engage in metabolic reprogramming of pro-inflammatory microglia through increased ATP production and modulation of signaling pathway involved in promoting glycolysis and cytokine release.

Exploring the clinical connections between epilepsy and diabetes mellitus: Promising therapeutic strategies utilizing agmatine and metformin

PURPOSE

Diabetes mellitus (DM) and epilepsy and the psychological and socio-economic implications that are associated with their treatments can be quite perplexing. Metformin is an antihyperglycemic medication that is used to treat type 2 DM. In addition, metformin elicits protective actions against multiple diseases, including neurodegeneration and epilepsy. Recent studies indicate that metformin alters the resident gut microbiota in favor of species producing agmatine, an arginine metabolite which, in addition to beneficially altering metabolic pathways, is a potent neuroprotectant and neuromodulant.

METHODS

We first examine the literature for epidemiological and clinical evidences linking DM and epilepsy. Next, basing our analyses on published literature, we propose the possible complementarity of agmatine and metformin in the treatment of DM and epilepsy.

RESULTS

Our analyses of the clinical data suggest a significant association between pathogeneses of epilepsy and DM. Further, both agmatine and metformin appear to be multimodal therapeutic agents and have robust antiepileptogenic and antidiabetic properties. Data from animal and clinical studies largely support the use of metformin/agmatine as a double-edged pharmacotherapeutic agent against DM and epilepsy, particularly in their concurrent pathological occurrences.

CONCLUSION

The present review explores the evidences and available data on possible uses of metformin/agmatine as pertinent antidiabetic and antiepileptic agents. Our hope is that this will stimulate further research on the therapeutic actions of these multimodal agents, particularly for subject-specific clinical outcomes.

Targeted Pyroptosis with Resveratrol Nanoparticles to Reduce Secondary Brain Injury and Post-Traumatic Epilepsy

Traumatic brain injury (TBI) is associated with high mortality and disability rates globally, leading to significant sequelae, particularly post-traumatic epilepsy (PTE), which severely impacts physical health and quality of life. TBI involves primary and secondary damage, with the latter exacerbating the initial injury through neuroinflammation, influencing the overall outcome. Recent studies highlight pyroptosis as a crucial factor in the spread of secondary brain damage and the development of epilepsy, making it a vital therapeutic target. While current TBI treatments focus on surgical and medical interventions to reduce intracranial pressure, addressing secondary damage has limited clinical translation, largely due to the blood-brain barrier (BBB) hindering drug accumulation in the affected area. Resveratrol (RV) shows promise as a therapeutic agent due to its anti-inflammatory properties. This study presents a nanoliposome (C-Lips/RV) engineered with cysteine-alanine-glutamine-lysine peptides to enhance RV delivery to the brain, mitigate pyroptosis, and reduce inflammation. In TBI rats, C-Lips/RV demonstrates a longer half-life and effective targeting of brain injury, leading to reduced pyroptosis and PTE, slowed secondary damage progression, and improved functional recovery. This work offers insights into managing secondary brain damage and PTE.

Ferroptosis and Pyroptosis in Epilepsy

Epilepsy is sudden, recurrent, and transient central nervous system dysfunction caused by abnormal discharge of neurons in the brain. Ferroptosis and pyroptosis are newly discovered ways of programmed cell death. One of the characteristics of ferroptosis is the oxidative stress generated by lipid peroxides. Similarly, pyroptosis has unique pro-inflammatory properties. As both oxidative stress and neuroinflammation are significant contributors to the pathogenesis of epilepsy, increasing evidence shows that ferroptosis and pyroptosis are closely related to epilepsy. This article reviews the current comprehension of ferroptosis and pyroptosis and elucidates potential mechanisms by which ferroptosis and pyroptosis may contribute to epilepsy. In addition, we also highlight the possible interactions between ferroptosis and pyroptosis because they reportedly coexist in many diseases, and increasing studies have demonstrated the convergence of pathways between the two. This is of great significance for explaining the occurrence and development of epilepsy and provides a new therapeutic perspective for the treatment of epilepsy.

Inflammasomes at the crossroads of traumatic brain injury and post-traumatic epilepsy

Post-traumatic epilepsy (PTE) is one of the most debilitating consequences of traumatic brain injury (TBI) and is one of the most drug-resistant forms of epilepsy. Novel therapeutic treatment options are an urgent unmet clinical need. The current focus in healthcare has been shifting to disease prevention, rather than treatment, though, not much progress has been made due to a limited understanding of the disease pathogenesis. Neuroinflammation has been implicated in the pathophysiology of traumatic brain injury and may impact neurological sequelae following TBI including functional behavior and post-traumatic epilepsy development. Inflammasome signaling is one of the major components of the neuroinflammatory response, which is increasingly being explored for its contribution to the epileptogenic mechanisms and a novel therapeutic target against epilepsy. This review discusses the role of inflammasomes as a possible connecting link between TBI and PTE with a particular focus on clinical and preclinical evidence of therapeutic inflammasome targeting and its downstream effector molecules for their contribution to epileptogenesis. Finally, we also discuss emerging evidence indicating the potential of evaluating inflammasome proteins in biofluids and the brain by non-invasive neuroimaging, as potential biomarkers for predicting PTE development.

The prenatal use of agmatine prevents social behavior deficits in VPA-exposed mice by activating the ERK/CREB/BDNF signaling pathway

BACKGROUND

According to reports, prenatal exposure to valproic acid can induce autism spectrum disorder (ASD)-like symptoms in both humans and rodents. However, the exact cause and therapeutic method of ASD is not fully understood. Agmatine (AGM) is known for its neuroprotective effects, and this study aims to explore whether giving agmatine hydrochloride before birth can prevent autism-like behaviors in mouse offspring exposed prenatally to valproic acid.

METHODS

In this study, we investigated the effects of AGM prenatally on valproate (VPA)-exposed mice. We established a mouse model of ASD by prenatally administering VPA. From birth to weaning, we evaluated mouse behavior using the marble burying test, open-field test, and three-chamber social interaction test on male offspring.

RESULTS

The results showed prenatal use of AGM relieved anxiety and hyperactivity behaviors as well as ameliorated sociability of VPA-exposed mice in the marble burying test, open-field test, and three-chamber social interaction test, and this protective effect might be attributed to the activation of the ERK/CREB/BDNF signaling pathway.

CONCLUSION

Therefore, AGM can effectively reduce the likelihood of offspring developing autism to a certain extent when exposed to VPA during pregnancy, serving as a potential therapeutic drug.

Human umbilical cord mesenchymal stem cell-derived exosomes attenuate neuroinflammation and oxidative stress through the NRF2/NF-κB/NLRP3 pathway

AIMS

We investigated whether human umbilical cord mesenchymal stem cell (hUC-MSC)-derived exosomes bear therapeutic potential against lipopolysaccharide (LPS)-induced neuroinflammation.

METHODS

Exosomes were isolated from hUC-MSC supernatant by ultra-high-speed centrifugation and characterized by transmission electron microscopy and western blotting. Inflammatory responses were induced by LPS in BV-2 cells, primary microglial cultures, and C57BL/6J mice. H2 O2 was also used to induce inflammation and oxidative stress in BV-2 cells. The effects of hUC-MSC-derived exosomes on inflammatory cytokine expression, oxidative stress, and microglia polarization were studied by immunofluorescence and western blotting.

RESULTS

Treatment with hUC-MSC-derived exosomes significantly decreased the LPS- or H2 O2 -induced oxidative stress and expression of pro-inflammatory cytokines (IL-6 and TNF-α) in vitro, while promoting an anti-inflammatory (classical M2) phenotype in an LPS-treated mouse model. Mechanistically, the exosomes increased the NRF2 levels and inhibited the LPS-induced NF-κB p65 phosphorylation and NLRP3 inflammasome activation. In contrast, the reactive oxygen species scavenger NAC and NF-κB inhibitor BAY 11-7082 also inhibited the LPS-induced NLRP3 inflammasome activation and switched to the classical M2 phenotype. Treatment with the NRF2 inhibitor ML385 abolished the anti-inflammatory and anti-oxidative effects of the exosomes.

CONCLUSION

hUC-MSC-derived exosomes ameliorated LPS/H2 O2 -induced neuroinflammation and oxidative stress by inhibiting the microglial NRF2/NF-κB/NLRP3 signaling pathway.

Role of Inflammatory Mechanisms in Major Depressive Disorder: From Etiology to Potential Pharmacological Targets

The involvement of central and peripheral inflammation in the pathogenesis and prognosis of major depressive disorder (MDD) has been demonstrated. The increase of pro-inflammatory cytokines (interleukin (IL)-1β, IL-6, IL-18, and TNF-α) in individuals with depression may elicit neuroinflammatory processes and peripheral inflammation, mechanisms that, in turn, can contribute to gut microbiota dysbiosis. Together, neuroinflammation and gut dysbiosis induce alterations in tryptophan metabolism, culminating in decreased serotonin synthesis, impairments in neuroplasticity-related mechanisms, and glutamate-mediated excitotoxicity. This review aims to highlight the inflammatory mechanisms (neuroinflammation, peripheral inflammation, and gut dysbiosis) involved in the pathophysiology of MDD and to explore novel anti-inflammatory therapeutic approaches for this psychiatric disturbance. Several lines of evidence have indicated that in addition to antidepressants, physical exercise, probiotics, and nutraceuticals (agmatine, ascorbic acid, and vitamin D) possess anti-inflammatory effects that may contribute to their antidepressant properties. Further studies are necessary to explore the therapeutic benefits of these alternative therapies for MDD.

Pyroptosis in neurodegenerative diseases: from bench to bedside

The central nervous system regulates all aspects of physiology to some extent. Neurodegenerative diseases (NDDs) lead to the progressive loss and dysfunction of neurons, which are particularly evident in Alzheimer's disease, Parkinson's disease, and many other conditions. NDDs are multifactorial diseases with complex pathogeneses, and there has been a rapid increase in the prevalence of NDDs. However, none of these diseases can be cured, making the development of novel treatment strategies an urgent necessity. Numerous studies have indicated how pyroptosis induces inflammation and affects many aspects of NDD. Therefore, components related to pyroptosis are potential therapeutic candidates and are attracting increasing attention. Here, we review the role of pyroptosis in the pathogenesis of NDDs and potential treatment options. Additionally, several of the current drugs and relevant inhibitors are discussed. Through this article, we provide theoretical support for exploring new therapeutic targets and updating clinical treatment strategies for NDDs. Notably, pyroptosis, a recently widely studied mode of cell death, is still under-researched compared to other traditional forms of cell death. Moreover, the focus of research has been on the onset and progression of NDDs, and the lack of organ-specific target discovery and drug development is a common problem for many basic studies. This urgent problem requires scientists and companies worldwide to collaborate in order to develop more effective drugs against NDDs.

Effects of amyloid β (Aβ)42 and Gasdermin D on the progression of Alzheimer's disease in vitro and in vivo through the regulation of astrocyte pyroptosis

PURPOSE

The study aimed to investigate whether astrocyte pyroptosis, and the subsequent neuroinflammatory response that exerts amyloid β (Aβ) neurotoxic effects, has an effect on endothelial cells, along with the underlying mechanisms.

METHODS

In vivo, 5 μL of disease venom was injected into the lateral ventricle of APP/PS1 mice for treatment. Pyroptosis was induced by treating astrocytes with Aβ42 in vitro. Small interfering RNA (siRNA) was used to silence caspase-1 and Gasdermin D (GSDMD) mRNA expression. Cell viability was determined using a CCK-8 detection kit. Scanning electron microscopy (SEM), Annexin V/propidium iodide (PI) double staining, RT-qPCR, immunofluorescence, western blotting, and enzyme-linked immunosorbent assay (ELISA) were used to detect cell pyroptosis. The degree of pathological damage to the brain and aortic tissue was assessed by hematoxylin-eosin staining and immunohistochemistry.

RESULTS

Aβ42 induced astrocyte pyroptosis dependent on the GSDMD/Gasdermin E (GSDME)/Caspase 11/NLRP3 pathway, releasing large amounts of inflammatory factors, such as TNF-α, IL-1α, IL-1β, and IL-18. Astrocyte pyroptosis caused endothelial cell dysfunction and release of large amounts of vasoconstrictors (ET and vWF). Knockdown of GSDMD reduced astrocyte pyroptosis in the cerebral cortex and hippocampal tissue, decreased the release of inflammatory factors IL-1 β and IL-18, reduced Aβ deposition and tau protein, increased the release of peripheral vasodilator substances (eNOS), and decreased the release of vasoconstrictor substances (ET, vWF), thereby reducing brain tissue damage and vascular injury in APP/PS1 mice.

CONCLUSION

Aβ42 induced astrocyte pyroptosis, while GSDMD knockout inhibited astrocyte pyroptosis, reduced the release of inflammatory factors, and alleviated brain tissue damage and vascular damage in APP/PS1 mice. Therefore, GSDMD is a novel therapeutic target for Alzheimer's disease.

PURPOSE

The study aimed to investigate whether astrocyte pyroptosis, and the subsequent neuroinflammatory response that exerts amyloid β (Aβ) neurotoxic effects, has an effect on endothelial cells, along with the underlying mechanisms.

METHODS

In vivo, 5 μL of disease venom was injected into the lateral ventricle of APP/PS1 mice for treatment. Pyroptosis was induced by treating astrocytes with Aβ42 in vitro. Small interfering RNA (siRNA) was used to silence caspase-1 and Gasdermin D (GSDMD) mRNA expression. Cell viability was determined using a CCK-8 detection kit. Scanning electron microscopy (SEM), Annexin V/propidium iodide (PI) double staining, RT-qPCR, immunofluorescence, western blotting, and enzyme-linked immunosorbent assay (ELISA) were used to detect cell pyroptosis. The degree of pathological damage to the brain and aortic tissue was assessed by hematoxylin-eosin staining and immunohistochemistry.

RESULTS

Aβ42 induced astrocyte pyroptosis dependent on the GSDMD/Gasdermin E (GSDME)/Caspase 11/NLRP3 pathway, releasing large amounts of inflammatory factors, such as TNF-α, IL-1α, IL-1β, and IL-18. Astrocyte pyroptosis caused endothelial cell dysfunction and release of large amounts of vasoconstrictors (ET and vWF). Knockdown of GSDMD reduced astrocyte pyroptosis in the cerebral cortex and hippocampal tissue, decreased the release of inflammatory factors IL-1 β and IL-18, reduced Aβ deposition and tau protein, increased the release of peripheral vasodilator substances (eNOS), and decreased the release of vasoconstrictor substances (ET, vWF), thereby reducing brain tissue damage and vascular injury in APP/PS1 mice.

CONCLUSION

Aβ42 induced astrocyte pyroptosis, while GSDMD knockout inhibited astrocyte pyroptosis, reduced the release of inflammatory factors, and alleviated brain tissue damage and vascular damage in APP/PS1 mice. Therefore, GSDMD is a novel therapeutic target for Alzheimer's disease.

Role of Pyroptosis, a Pro-inflammatory Programmed Cell Death, in Epilepsy

Epilepsy is one of the most common serious brain diseases worldwide. Programmed cell death (PCD), a cellular self-destruction phenomenon, has been greatly documented in neurodegenerative diseases. Pyroptosis is a well-known pro-inflammatory PCD, and its involvement in epilepsy has been reported in animal models of epilepsy and also epileptic patients. Canonical (caspase-1-dependent) and non-canonical (caspase-1-independent) pathways are two main mechanisms implicated in pyroptotic cell death. Mouse caspase-11 or human analogues caspase-4/5 induce the non-canonical pathway. In both pathways, membrane gasdermin (GSDMD) pores contribute to pro-inflammatory cytokine release and lead to membrane destabilization and cell lysis. IL-1β and IL-18 are pro-inflammatory cytokines that are released following pyroptotic PCD. Brain inflammation increases excitability in the nervous system, promotes seizure activity, and is probably associated with the molecular and synaptic changes involved in epileptogenesis. Pro-inflammatory cytokines affect the glutamate and GABA neurotransmitter release as well as their receptors, thereby resulting in seizure activity. This review is intended to provide an overview of the current published works on pyroptotic cell death in epilepsy. The mechanisms by which pro-inflammatory cytokines, including IL-1β and IL-18 can promote epileptic discharges were also collected. According to this survey, since the involvement of pyroptosis in the development of epilepsy has been established, pyroptosis-targeted therapies may represent a novel anti-epileptogenic strategy.

A Novel Prognostic Pyroptosis-Related Gene Signature Correlates to Oxidative Stress and Immune-Related Features in Gliomas

Gliomas are highly invasive and aggressive tumors having the highest incidence rate of brain cancer. Identifying effective prognostic and potential therapeutic targets is necessitated. The relationship of pyroptosis, a form of programmed cellular death, with gliomas remains elusive. We constructed and validated a prognostic model for gliomas using pyroptosis-related genes. Differentially expressed pyroptosis-related genes were screened using the "limma" package. Based on LASSO-Cox regression, nine significant genes including CASP1, CASP3, CASP6, IL32, MKI67, MYD88, PRTN3, NOS1, and VIM were employed to construct a prognostic model in the TCGA cohort; the results were validated in the CGGA cohort. According to the median risk score, the patients were classified into two risk groups, namely, high- and low-risk groups. Patients at high risk had worse prognoses relative to those at low risk evidenced by the Kaplan-Meier curve analysis. The two groups exhibited differences in immune cell infiltration and TMB scores, with high immune checkpoint levels, TMB scores, and immune cell infiltration levels in the high-risk group. KEGG and GO analyses suggested enrichment in immune-related pathways. Furthermore, we found that the genes in our signature strongly correlated with oxidative stress-related pathways and the subgroups exhibited different ssGSEA scores. Some small molecules targeted the genes in the model, and we verified their drug sensitivities between the risk groups. The scRNA-seq dataset, GSE138794, was processed using the "Seurat" package to assess the level of risk gene expression in specific cell types. Finally, the MYD88 level was lowered in the U87 glioma cell line using si-RNA constructs. Cellular proliferation was impaired, and fewer pyroptosis-related cytokines were released upon exposure to LPS. In summary, we built a pyroptosis-related gene model that accurately classified glioma patients into high- and low-risk groups. The findings suggest that the signature may be an effective prognostic predictive tool for gliomas.

Blockade of Kv1.3 Potassium Channel Inhibits Microglia-Mediated Neuroinflammation in Epilepsy

Epilepsy is a chronic neurological disorder whose pathophysiology relates to inflammation. The potassium channel Kv1.3 in microglia has been reported as a promising therapeutic target in neurological diseases in which neuroinflammation is involved, such as multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD), and middle cerebral artery occlusion/reperfusion (MCAO/R). Currently, little is known about the relationship between Kv1.3 and epilepsy. In this study, we found that Kv1.3 was upregulated in microglia in the KA-induced mouse epilepsy model. Importantly, blocking Kv1.3 with its specific small-molecule blocker 5-(4-phenoxybutoxy)psoralen (PAP-1) reduced seizure severity, prolonged seizure latency, and decreased neuronal loss. Mechanistically, we further confirmed that blockade of Kv1.3 suppressed proinflammatory microglial activation and reduced proinflammatory cytokine production by inhibiting the Ca2+/NF-κB signaling pathway. These results shed light on the critical function of microglial Kv1.3 in epilepsy and provided a potential therapeutic target.

DHA and EPA Prevent Seizure and Depression-Like Behavior by Inhibiting Ferroptosis and Neuroinflammation via Different Mode-of-actions in a Pentylenetetrazole-Induced Kindling Model in Mice

SCOPE

It has been reported that eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have anticonvulsant effects, yet the respective mechanism of EPA and DHA on epilepsy are still unclarified. This study aimed to investigate the effect of EPA and DHA on pentylenetetrazol (PTZ) induced seizures and depression.

METHODS AND RESULTS

The administration of EPA and DHA at a dose of 1% (w/w) significantly inhibited PTZ-induced seizures and depressive-like behavior, whereas EPA outcompetes DHA. Further mechanistic studies revealed that the higher effect of EPA can be partly attributed to the promotion of M2 polarization, inhibition of M1 polarization of microglia, and lower iron content in the brain, resulting from the stronger activation of nuclear factor E2-related factor 2 (Nrf2). We found that DHA and EPA comparably inhibited NLRP3 inflammasome activation but with different mode-of-actions: EPA preferred to inhibit the binding of NLRP3 and ASC, while DHA decreased the protein levels of ASC and Caspase-1.

CONCLUSIONS

These results indicated that DHA and EPA could efficaciously alleviate PTZ-induced seizure and depressive-like behavior but with different efficiency and molecular mechanisms. This article is protected by copyright. All rights reserved.

Distinct Cell-specific Roles of NOX2 and MyD88 in Epileptogenesis

It is well established that temporal lobe epilepsy (TLE) is often related to oxidative stress and neuroinflammation. Both processes subserve alterations observed in epileptogenesis and ultimately involve distinct classes of cells, including astrocytes, microglia, and specific neural subtypes. For this reason, molecules associated with oxidative stress response and neuroinflammation have been proposed as potential targets for therapeutic strategies. However, these molecules can participate in distinct intracellular pathways depending on the cell type. To illustrate this, we reviewed the potential role of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) and myeloid differentiation primary response 88 (MyD88) in astrocytes, microglia, and neurons in epileptogenesis. Furthermore, we presented approaches to study genes in different cells, employing single-cell RNA-sequencing (scRNAseq) transcriptomic analyses, transgenic technologies and viral serotypes carrying vectors with specific promoters. We discussed the importance of identifying particular roles of molecules depending on the cell type, endowing more effective therapeutic strategies to treat TLE.

Research Progress of Pyroptosis in Alzheimer's Disease

Alzheimer's disease (AD) is a disease characterized by insidious and progressive neurodegeneration, with clinical syndromes of memory and visuospatial skills damage. The pathogenic mechanism of AD is complex in which neural inflammation and neuron death play important roles. Pyroptosis, an inflammatory programmed cell death, has been reported to be involved in neuron death. Pyroptosis is executed by the protein family of gasdermins which punch pores on plasma membrane when activated by the upstream signals including the activation of NLRP3 and caspases, and subsequently triggers the inflammatory cascades featured by the release of interleukin (IL) -1β and IL-18. Herein, we summarized the current research on the roles of neuron pyroptosis in AD, aiming to provide a comprehensive view of the molecular mechanisms underlying AD pathogenesis and potential therapeutic targets for AD.

Agmatine Mitigates Inflammation-Related Oxidative Stress in BV-2 Cells by Inducing a Pre-Adaptive Response

Neuroinflammation and microglial activation, common components of most neurodegenerative diseases, can be imitated in vitro by challenging microglia cells with Lps. We here aimed to evaluate the effects of agmatine pretreatment on Lps-induced oxidative stress in a mouse microglial BV-2 cell line. Our findings show that agmatine suppresses nitrosative and oxidative burst in Lps-stimulated microglia by reducing iNOS and XO activity and decreasing O₂^- levels, arresting lipid peroxidation, increasing total glutathione content, and preserving GR and CAT activity. In accordance with these results, agmatine suppresses inflammatory NF-kB, and stimulates antioxidant Nrf2 pathway, resulting in decreased TNF, IL-1 beta, and IL-6 release, and reduced iNOS and COX-2 levels. Together with increased ARG1, CD206 and HO-1 levels, our results imply that, in inflammatory conditions, agmatine pushes microglia towards an anti-inflammatory phenotype. Interestingly, we also discovered that agmatine alone increases lipid peroxidation end product levels, induces Nrf2 activation, increases total glutathione content, and GPx activity. Thus, we hypothesize that some of the effects of agmatine, observed in activated microglia, may be mediated by induced oxidative stress and adaptive response, prior to Lps stimulation.

Role of Stat3 in NLRP3/caspase-1-mediated hippocampal neuronal pyroptosis in epileptic mice

Epilepsy, a fairly common neurological disorder, is linked to various sequelae and greatly impairs the quality of life. Meanwhile, there is evidence to suggest an association between pyroptosis and epilepsy. Accordingly, the current study sought to determine the role of signal transduction activator of transcription 3 (Stat3) in pyroptosis in epileptic mice. Firstly, epileptic mouse models were induced by lithium chloride, atropine, and pilocarpine, and HT22 cells were treated with lipopolysaccharide (LPS) to establish hippocampal neuronal inflammation models. Subsequently, Stat3, NOD-like receptor protein 3 (NLRP3), cleaved-caspase-1, gasdermin D (GSDMD)-N, activated Stat3 (p-Stat3), and H3K9Ac levels were detected in the mouse hippocampus and HT22 cells. Morris water maze test was further performed to detect changes in the learning and memory abilities of epileptic mice, and hematoxylin-eosin staining and Nissl staining were conducted to detect the pathological injury. HT22 cell proliferation and apoptosis were also detected using a cell counting kit-8 assay and flow cytometry. An enzyme-linked immunosorbent assay was adopted to detect Interleukin (IL)-1β and IL-18 concentrations in the mouse hippocampus and HT22 cells. Furthermore, the enrichment of H3K9Ac and p-Stat3 in the NLRP3 promoter region was detected with the help of a chromatin immunoprecipitation assay. The obtained findings revealed that Stat3 was highly-expressed in the hippocampus of epileptic mice and LPS-treated HT22 cells. Meanwhile, Stat3 silencing brought about improvements in the learning and memory abilities of the mice, in addition to alleviation of hippocampal neuronal damage and pyroptosis-related factors in hippocampal tissue and HT22 cells. We also observed that Stat3 bound to the NLRP3 promoter to promote H3K9 acetylation and NLRP3 transcription. Moreover, increasing H3K9Ac in cells annulled the inhibition of silencing Stat3 on neuronal pyroptosis. To conclude, our findings revealed that Stat3 bound to the NLRP3 promoter to augment H3K9 acetylation, NLRP3 transcription, and NLRP3/caspase-1-mediated neuronal pyroptosis, resulting in aggravation of neuronal damage in epileptic mice. This article is protected by copyright. All rights reserved.