Relationship Between the Pyroptosis Pathway and Epilepsy: A Bioinformatic Analysis

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.

Mechanism of NLRP3 Inflammasome in Epilepsy and Related Therapeutic Agents

Epilepsy is one of the most widespread and complex diseases in the central nervous system (CNS), affecting approximately 65 million people globally, an important factor resulting in neurological disability-adjusted life year (DALY) and progressive cognitive dysfunction. Medication is the most essential treatment. The currently used drugs have shown drug resistance in some patients and only control symptoms; the development of novel and more efficacious pharmacotherapy is imminent. Increasing evidence suggests neuroinflammation is involved in the occurrence and development of epilepsy, and high expression of NLRP3 inflammasome has been observed in the temporal lobe epilepsy (TLE) brain tissue of patients and animal models. The inflammasome is a crucial cause of neuroinflammation by activating IL-1β and IL-18. Many preclinical studies have confirmed that regulating NLRP3 inflammasome pathway can prevent the development of epilepsy, reduce the severity of epilepsy, and play a neuroprotective role. Therefore, regulating NLRP3 inflammasome could be a potential target for epilepsy treatment. In summary, this review describes the priming and activation of inflammasome and its biological function in the progression of epilepsy. In addition, we reviewes the current pharmacological researches for epilepsy based on the regulation of NLRP3 inflammasome, aiming to provide a basis and reference for developing novel antiepileptic drugs.

Expression and correlation of the NOD-like receptor family, pyrin domain-containing 3 inflammasome and the silent information regulator 1 in patients with drug-resistant epilepsy

BACKGROUND

The NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammatory pathway is implicated in the development of epilepsy and can be suppressed by the activation of the silent information regulator 1 (SIRT1). However, the expression and correlation of the NLRP3 pathway and SIRT1 in drug-resistant epilepsy (DRE) remain unknown.

METHODS

This study evaluated the histopathology of the cerebral cortex from nine patients with DRE and eight patients with cavernous haemangioma undergoing surgical treatment. It analysed the expression of the NLRP3, interleukin-1β (IL-1β), caspase-1 and SIRT1 using immunohistochemistry. Additionally, the contents of NLRP3, caspase-1, IL-1β and SIRT1 in the serum samples of the included study participants were determined using ELISA method. The correlation between the NLRP3 pathway and the SIRT1 was assessed using Spearman's correlation analysis.

RESULTS

The expression of NLRP3, caspase-1 and IL-1β in the cerebral cortex of patients with DRE was elevated, with the NLRP3 expression being negatively correlated with the SIRT1 expression. Furthermore, IL-1β in serum was upregulated in patients with DRE. The correlation between the content of serum SIRT1 and NLRP3, caspase-1 and IL-1β in patients with DRE was not significant. Notably, serum caspase-1 levels were obviously higher in patients with bilateral hippocampal sclerosis than in patients with unilateral hippocampal sclerosis.

CONCLUSIONS

The current results indicate that the expression of the NLRP3/caspase-1/IL-1β pathway is significantly upregulated in patients with DRE and that it is partially correlated with the SIRT1 expression. This study is important for understanding the pathophysiology of DRE and developing new treatment strategies for it.

The Role of Histone Deacetylases in NLRP3 Inflammasomesmediated Epilepsy

Epilepsy is one of the most common brain disorders that not only causes death worldwide, but also affects the daily lives of patients. Previous studies have revealed that inflammation plays an important role in the pathophysiology of epilepsy. Activation of inflammasomes can promote neuroinflammation by boosting the maturation of caspase-1 and the secretion of various inflammatory effectors, including chemokines, interleukins, and tumor necrosis factors. With the in-depth research on the mechanism of inflammasomes in the development of epilepsy, it has been discovered that NLRP3 inflammasomes may induce epilepsy by mediating neuronal inflammatory injury, neuronal loss and blood-brain barrier dysfunction. Therefore, blocking the activation of the NLRP3 inflammasomes may be a new epilepsy treatment strategy. However, the drugs that specifically block NLRP3 inflammasomes assembly has not been approved for clinical use. In this review, the mechanism of how HDACs, an inflammatory regulator, regulates the activation of NLRP3 inflammasome is summarized. It helps to explore the mechanism of the HDAC inhibitors inhibiting brain inflammatory damage so as to provide a potential therapeutic strategy for controlling the development of epilepsy.

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.

The NLRP3 inflammasome is a potential mechanism and therapeutic target for perioperative neurocognitive disorders

Perioperative neurocognitive disorders (PNDs) are frequent complications associated with cognitive impairment during the perioperative period, including acute postoperative delirium and long-lasting postoperative cognitive dysfunction. There are some risk factors for PNDs, such as age, surgical trauma, anesthetics, and the health of the patient, but the underlying mechanism has not been fully elucidated. Pyroptosis is a form of programmed cell death that is mediated by the gasdermin protein and is involved in cognitive dysfunction disorders. The canonical pathway induced by nucleotide oligomerization domain (NOD)-, leucine-rich repeat (LRR)- and pyrin domain-containing protein 3 (NLRP3) inflammasomes contributes to PNDs, which suggests that targeting NLRP3 inflammasomes may be an effective strategy for the treatment of PNDs. Therefore, inhibiting upstream activators and blocking the assembly of the NLRP3 inflammasome may attenuate PNDs. The present review summarizes recent studies and systematically describes the pathogenesis of NLRP3 activation and regulation and potential therapeutics targeting NLRP3 inflammasomes in PNDs patients.

Neuronal nitric oxide synthase/reactive oxygen species pathway is involved in apoptosis and pyroptosis in epilepsy

Dysfunction of neuronal nitric oxide synthase contributes to neurotoxicity, which triggers cell death in various neuropathological diseases, including epilepsy. Studies have shown that inhibition of neuronal nitric oxide synthase activity increases the epilepsy threshold, that is, has an anticonvulsant effect. However, the exact role and potential mechanism of neuronal nitric oxide synthase in seizures are still unclear. In this study, we performed RNA sequencing, functional enrichment analysis, and weighted gene coexpression network analysis of the hippocampus of tremor rats, a rat model of genetic epilepsy. We found damaged hippocampal mitochondria and abnormal succinate dehydrogenase level and Na⁺-K⁺-ATPase activity. In addition, we used a pilocarpine-induced N2a cell model to mimic epileptic injury. After application of neuronal nitric oxide synthase inhibitor 7-nitroindazole, changes in malondialdehyde, lactate dehydrogenase and superoxide dismutase, which are associated with oxidative stress, were reversed, and the increase in reactive oxygen species level was reversed by 7-nitroindazole or reactive oxygen species inhibitor N-acetylcysteine. Application of 7-nitroindazole or N-acetylcysteine downregulated the expression of caspase-3 and cytochrome c and reversed the apoptosis of epileptic cells. Furthermore, 7-nitroindazole or N-acetylcysteine downregulated the abnormally high expression of NLRP3, gasdermin-D, interleukin-1β and interleukin-18. This indicated that 7-nitroindazole and N-acetylcysteine each reversed epileptic cell death. Taken together, our findings suggest that the neuronal nitric oxide synthase/reactive oxygen species pathway is involved in pyroptosis of epileptic cells, and inhibiting neuronal nitric oxide synthase activity or its induced oxidative stress may play a neuroprotective role in epilepsy.

Key biomarkers and latent pathways of dysferlinopathy: Bioinformatics analysis and in vivo validation

Background

Dysferlinopathy refers to a group of muscle diseases with progressive muscle weakness and atrophy caused by pathogenic mutations of the DYSF gene. The pathogenesis remains unknown, and currently no specific treatment is available to alter the disease progression. This research aims to investigate important biomarkers and their latent biological pathways participating in dysferlinopathy and reveal the association with immune cell infiltration.

Methods

GSE3307 and GSE109178 were obtained from the Gene Expression Omnibus (GEO) database. Based on weighted gene co-expression network analysis (WGCNA) and differential expression analysis, coupled with least absolute shrinkage and selection operator (LASSO), the key genes for dysferlinopathy were identified. Functional enrichment analysis Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were applied to disclose the hidden biological pathways. Following that, the key genes were approved for diagnostic accuracy of dysferlinopathy based on another dataset GSE109178, and quantitative real-time polymerase chain reaction (qRT-PCR) were executed to confirm their expression. Furthermore, the 28 immune cell abundance patterns in dysferlinopathy were determined with single-sample GSEA (ssGSEA).

Results

1,579 differentially expressed genes (DEGs) were screened out. Based on WGCNA, three co-expression modules were obtained, with the MEskyblue module most strongly correlated with dysferlinopathy. 44 intersecting genes were recognized from the DEGs and the MEskyblue module. The six key genes MVP, GRN, ERP29, RNF128, NFYB and KPNA3 were discovered through LASSO analysis and experimentally verified later. In a receiver operating characteristic analysis (ROC) curve, the six hub genes were shown to be highly valuable for diagnostic purposes. Furthermore, functional enrichment analysis highlighted that these genes were enriched mainly along the ubiquitin-proteasome pathway (UPP). Ultimately, ssGSEA showed a significant immune-cell infiltrative microenvironment in dysferlinopathy patients, especially T cell, macrophage, and activated dendritic cell (DC).

Conclusion

Six key genes are identified in dysferlinopathy with a bioinformatic approach used for the first time. The key genes are believed to be involved in protein degradation pathways and the activation of muscular inflammation. And several immune cells, such as T cell, macrophage and DC, are considered to be implicated in the progression of dysferlinopathy.