Ion Channels in Genetic Epilepsy: From Genes and Mechanisms to Disease-Targeted Therapies

Investigation of epilepsy-related genes in a Drosophila model

Complex genetic architecture is the major cause of heterogeneity in epilepsy, which poses challenges for accurate diagnosis and precise treatment. A large number of epilepsy candidate genes have been identified from clinical studies, particularly with the widespread use of next-generation sequencing. Validating these candidate genes is emerging as a valuable yet challenging task. Drosophila serves as an ideal animal model for validating candidate genes associated with neurogenetic disorders such as epilepsy, due to its rapid reproduction rate, powerful genetic tools, and efficient use of ethological and electrophysiological assays. Here, we systematically summarize the advantageous techniques of the Drosophila model used to investigate epilepsy genes, including genetic tools for manipulating target gene expression, ethological assays for seizure-like behaviors, electrophysiological techniques, and functional imaging for recording neural activity. We then introduce several typical strategies for identifying epilepsy genes and provide new insights into gene‒gene interactions in epilepsy with polygenic causes. We summarize well-established precision medicine strategies for epilepsy and discuss prospective treatment options, including drug therapy and gene therapy for genetic epilepsy based on the Drosophila model. Finally, we also address genetic counseling and assisted reproductive technology as potential approaches for the prevention of genetic epilepsy.

Transcriptomic analyses of human brains with Alzheimer's disease identified dysregulated epilepsy-causing genes

BACKGROUND & OBJECTIVE

Alzheimer's Disease (AD) patients at multiple stages of disease progression have a high prevalence of seizures. However, whether AD and epilepsy share pathophysiological changes remains poorly defined. In this study, we leveraged high-throughput transcriptomic data from sporadic AD cases at different stages of cognitive impairment across multiple independent cohorts and brain regions to examine the role of epilepsy-causing genes.

METHODS

Epilepsy-causing genes were manually curated, and their expression levels were analyzed across bulk transcriptomic data from three AD cohorts and three brain regions. RNA-seq data from sporadic AD and control cases from the Knight ADRC, MSBB, and ROSMAP cohorts were processed and analyzed under the same analytical pipeline. An integrative clustering approach employing machine learning and multi-omics data was employed to identify molecularly defined profiles with different cognitive scores.

RESULTS

We found several epilepsy-associated genes/pathways significantly dysregulated in a group of AD patients with more severe cognitive impairment. We observed 15 genes consistently downregulated across the three cohorts, including sodium and potassium channels genes, suggesting that these genes play fundamental roles in cognitive function or AD progression. Notably, we found 25 of these genes dysregulated in earlier stages of AD and become worse with AD progression.

CONCLUSION

Our findings revealed that epilepsy-causing genes showed changes in the early and late stages of AD progression, suggesting that they might be playing a role in AD progression. We can not establish directionality or cause-effect with our findings. However, changes in the epilepsy-causing genes might underlie the presence of seizures in AD patients, which might be present before or concurrently with the initial stages of AD.

Recent advances in nanotherapy-based treatment of epilepsy

Epilepsy is a complex neurological disorder characterized by recurrent seizures affecting millions of people worldwide. Despite advances in drug therapy, a significant proportion of patients remain resistant to conventional antiepileptic drugs (AEDs) due to challenges such as impermeability of the blood-brain barrier (BBB), multidrug resistance, and multifaceted epileptogenesis. Nanotechnology offers promising strategies to overcome these barriers by enhancing drug delivery across the BBB, improving target specificity and minimizing systemic side effects. This review explores recent advances in different innovative strategies of nanodelivery systems for epilepsy therapy, and we will discuss the design principles, mechanisms of action and therapeutic efficacy of these nanodelivery systems. In addition, we discuss the challenges and limitations that hinder the clinical translation of nanomedicine-based therapies for epilepsy. We emphasize the need for personalized and multidisciplinary approaches as well as the importance of continued research and interdisciplinary collaboration in order to translate these innovative strategies into effective therapies. Ultimately, the use of nanotechnology has the potential to enhance seizure control, reduce the burden of epilepsy, and improve the quality of life of patients affected by this complex neurological disorder. Nanotechnology-based drug delivery systems may usher in a new era of precision medicine for epilepsy treatment.

Bio-Nano Innovations Targeting the Neurovascular Complex for Epilepsy Treatment

Epilepsy is a prevalent chronic neurological disorder characterized by seizures resulting from an imbalance between excitatory and inhibitory neurons. While pharmacotherapy remains the standard treatment, traditional pharmacotherapy faces significant challenges, including poor brain penetration, high drug resistance rates, and providing only symptomatic relief, rather than addressing the underlying causes for a comprehensive cure. Recently, the neurovascular complex (NVC) has gained attention for its critical role in the development and progression of epilepsy. Simultaneously, various innovative bio-nanotechnology systems have emerged, specifically designed to enhance drug delivery across the brain and enable precise targeting within the lesion. Herein, this review begins by outlining the core NVC involved in epilepsy treatment, breaking it down into four key components: the blood-brain barrier (BBB), neurons, glial cells, and the microenvironment. The viability of targeting NVC to improve epilepsy therapy is analyzed. Next, innovative bio-nanotechnology systems, detailing their design principles, construction strategies, and preclinical evaluations in epilepsy therapy are highlighted. Finally, the prospects for next-generation nanotechnologies and the challenges that must be overcome for effective clinical translation are discussed. Overall, this review aims to guide the development of more efficient and precise bio-nano therapies, ultimately enhancing treatment outcomes for epilepsy patients.

Comprehensive transcriptome analysis and lncRNA-miRNA-mRNA establishment of schizophrenia based on induced pluripotent stem cells

BACKGROUND

Schizophrenia (SCZ) is a complex and heterogeneous disorder with unclear underlying mechanisms. Identifying key gene diseases and constructing biological regulatory networks were beneficial in expanding our understanding of the pathogenesis of SCZ.

METHODS

We conducted whole transcriptome sequencing of induced pluripotent stem cells (iPSCs) derived from 5 SCZ patients and 5 healthy controls to analyze differences in mRNA and non-coding RNA expression profiles. Differentially expressed mRNAs (DE mRNAs) were explored for their functions and pathways, and lncRNA-miRNA-mRNA regulatory networks were constructed to understand post-transcriptional regulation mechanisms. Additionally, correlation analyses between competitive endogenous RNAs (ceRNAs), hub genes, and clinical phenotypes of SCZ patients (positive/negative and cognitive symptoms) were performed.

RESULTS

We identified 139 DE mRNAs, 154 lncRNAs, and 19 miRNAs. Significant enrichment of pathways related to apoptosis, inflammatory response, hypoxia, KRAS signaling, and IL6_JAK_STAT3 signaling were observed. Ten hub genes, CCK, CCNA1, CDH5, GATA2, GRPR, NPY, PRKG2, TLE6, ZEB1and ZEB2, were identified, of which ZEB1 and GATA2 were positively correlated with positive symptoms of SCZ, while CDH5 and GRPR were associated with memory. The ceRNA regulatory network (TPM1-AS/ADPGK-AS1/MIRLET7BHG-hsa-mir-3180/3180-3p-LRRC15/TUBA8 and MIRLET7BHG- hsa-mir-3187-3p- CCDC92/ TDRD6/ TMEM26/ ATP1A2) was established, which was also significantly associated with positive, negative and cognitive symptoms of SCZ.

CONCLUSIONS

This study identified potential hub genes, pathways, and lncRNA-miRNA-mRNA regulatory networks in iPSCs that provide new insights into the molecular mechanisms of SCZ. The identified hub genes and ceRNA showed significant correlations with various clinical phenotypes of SCZ, offering potential biomarkers and therapeutic targets.

Autism Spectrum Disorder and Epilepsy: Pathogenetic Mechanisms and Therapeutic Implications

The co-occurrence of autism spectrum disorder (ASD) and epilepsy is a complex neurological condition that presents significant challenges for both patients and clinicians. ASD is a group of complex developmental disorders characterized by the following: (1) Social communication difficulties: challenges in understanding and responding to social cues, initiating and maintaining conversations, and developing and maintaining relationships. (2) Repetitive behaviors: engaging in repetitive actions, such as hand-flapping, rocking, or lining up objects. (3) Restricted interests: focusing intensely on specific topics or activities, often to the exclusion of other interests. (4) Sensory sensitivities: over- or under-sensitivity to sensory input, such as sounds, touch, tastes, smells, or sights. These challenges can significantly impact individuals' daily lives and require specialized support and interventions. Early diagnosis and intervention can significantly improve the quality of life for individuals with ASD and their families. Epilepsy is a chronic brain disorder characterized by recurrent unprovoked (≥2) seizures that occur >24 h apart. Single seizures are not considered epileptic seizures. Epilepsy is often idiopathic, but various brain disorders, such as malformations, strokes, and tumors, can cause symptomatic epilepsy. While these two conditions were once considered distinct, growing evidence suggests a substantial overlap in their underlying neurobiology. The prevalence of epilepsy in individuals with ASD is significantly higher than in the general population. This review will explore the epidemiology of this comorbidity, delve into the potential mechanisms linking ASD and epilepsy, and discuss the implications for diagnosis, treatment, and management.

Biased signaling in drug discovery and precision medicine

Receptors are crucial for converting chemical and environmental signals into cellular responses, making them prime targets in drug discovery, with about 70% of drugs targeting these receptors. Biased signaling, or functional selectivity, has revolutionized drug development by enabling precise modulation of receptor signaling pathways. This concept is more firmly established in G protein-coupled receptor and has now been applied to other receptor types, including ion channels, receptor tyrosine kinases, and nuclear receptors. Advances in structural biology have further refined our understanding of biased signaling. This targeted approach enhances therapeutic efficacy and potentially reduces side effects. Numerous biased drugs have been developed and approved as therapeutics to treat various diseases, demonstrating their significant therapeutic potential. This review provides a comprehensive overview of biased signaling in drug discovery and disease treatment, highlighting recent advancements and exploring the therapeutic potential of these innovative modulators across various diseases.

The epilepsy-autism phenotype associated with developmental and epileptic encephalopathies: New mechanism-based therapeutic options

Epilepsy and autism often co-occur in genetic developmental and epileptic encephalopathies (DEEs), but their underlying neurobiological processes remain poorly understood, complicating treatment. Advances in molecular genetics and understanding the neurodevelopmental pathogenesis of the epilepsy-autism phenotype may lead to mechanism-based treatments for children with DEEs and autism. Several genes, including the newly reported PPFIA3, MYCBP2, DHX9, TMEM63B, and RELN, are linked to various neurodevelopmental and epileptic disorders, intellectual disabilities, and autistic features. These findings underscore the clinical heterogeneity of genetic DEEs and suggest diverse neurobiological mechanisms influenced by genetic, epigenetic, and environmental factors. Mechanisms linking epilepsy and autism include γ-aminobutyric acidergic (GABAergic) signaling dysregulation, synaptic plasticity, disrupted functional connectivity, and neuroinflammatory responses. GABA system abnormalities, critical for inhibitory neurotransmission, contribute to both conditions. Dysregulation of the mechanistic target of rapamycin (mTOR) pathway and neuroinflammation are also pivotal, affecting seizure generation, drug resistance, and neuropsychiatric comorbidities. Abnormal synaptic function and connectivity further underscore the epilepsy-autism phenotype. New treatment options targeting specific mechanisms linked to the epilepsy-autism phenotype are emerging. Genetic variants in potassium channel genes like KCNQ2 and KCNT1 are frequent causes of early onset DEEs. Personalized treatments like retigabine and quinidine have been explored with heterogeneous responses. Efforts are ongoing to develop more effective KCNQ activators and KCNT1 blockers. SCN1A genetic variants, particularly in Dravet syndrome, show potential for treatment of autistic symptoms with low-dose clonazepam, fenfluramine, and cannabidiol, although human trials have yet to consistently replicate animal model successes. Early intervention before the age of 3 years, particularly in SCN1A- and tuberous sclerosis complex-related DEEs, is crucial. Additionally, targeting the mTOR pathway shows promise for seizure control and managing epilepsy-associated comorbidities. Understanding the distinct autism spectrum disorder phenotype in DEEs and implementing early behavioral interventions are essential for improving outcomes. Despite genetic advances, significant challenges persist in diagnosing and treating DEE-associated epilepsy-autism phenotypes. Future clinical trials should adopt precision health approaches to improve neurodevelopmental outcomes.

Advancements in Surgical Therapies for Drug-Resistant Epilepsy: A Paradigm Shift towards Precision Care

Epilepsy, a prevalent neurological disorder characterized by recurrent seizures, affects millions worldwide, with a significant proportion resistant to pharmacological treatments. Surgical interventions have emerged as pivotal in managing drug-resistant epilepsy (DRE), aiming to reduce seizure frequency or achieve seizure freedom. Traditional resective surgeries have evolved with technological advances, enhancing precision and safety. Neurostimulation techniques, such as responsive neurostimulation (RNS) and deep brain stimulation (DBS), now provide personalized, real-time seizure management, offering alternatives to traditional surgery. Minimally invasive ablative methods, such as laser interstitial thermal therapy (LITT) and Magnetic Resonance-guided Focused Ultrasound (MRgFUS), allow for targeted destruction of epileptogenic tissue with reduced risks and faster recovery times. The use of stereo-electroencephalography (SEEG) and robotic assistance has further refined surgical precision, enhancing outcomes. These advancements mark a paradigm shift towards precision medicine in epilepsy care, promising improved seizure management and quality of life for patients globally. This review outlines the latest innovations in epilepsy surgery, emphasizing their mechanisms and clinical implications to improve outcomes for patients with DRE.

Pathogenesis, diagnosis, and treatment of epilepsy: electromagnetic stimulation-mediated neuromodulation therapy and new technologies

Epilepsy is a severe, relapsing, and multifactorial neurological disorder. Studies regarding the accurate diagnosis, prognosis, and in-depth pathogenesis are crucial for the precise and effective treatment of epilepsy. The pathogenesis of epilepsy is complex and involves alterations in variables such as gene expression, protein expression, ion channel activity, energy metabolites, and gut microbiota composition. Satisfactory results are lacking for conventional treatments for epilepsy. Surgical resection of lesions, drug therapy, and non-drug interventions are mainly used in clinical practice to treat pain associated with epilepsy. Non-pharmacological treatments, such as a ketogenic diet, gene therapy for nerve regeneration, and neural regulation, are currently areas of research focus. This review provides a comprehensive overview of the pathogenesis, diagnostic methods, and treatments of epilepsy. It also elaborates on the theoretical basis, treatment modes, and effects of invasive nerve stimulation in neurotherapy, including percutaneous vagus nerve stimulation, deep brain electrical stimulation, repetitive nerve electrical stimulation, in addition to non-invasive transcranial magnetic stimulation and transcranial direct current stimulation. Numerous studies have shown that electromagnetic stimulation-mediated neuromodulation therapy can markedly improve neurological function and reduce the frequency of epileptic seizures. Additionally, many new technologies for the diagnosis and treatment of epilepsy are being explored. However, current research is mainly focused on analyzing patients' clinical manifestations and exploring relevant diagnostic and treatment methods to study the pathogenesis at a molecular level, which has led to a lack of consensus regarding the mechanisms related to the disease.

Role of voltage-gated chloride channels in epilepsy: current insights and future directions

Epilepsy is a prevalent chronic neurological disorder characterised by recurrent seizures caused by excessive neuronal discharge. Disruptions in chloride ion homeostasis significantly affect neuronal excitability, and play a crucial role in the pathophysiology of this disorder. This review highlights the emerging importance of chloride voltage-gated channels in epilepsy, which has been largely underappreciated compared to cation channels. Recent studies have suggested that genetic alterations in chloride channels, such as CLCN1, CLCN2, CLCN3, CLCN4, and CLCN6, contribute to neuronal excitability and seizure susceptibility, with variations in these channels acting more as susceptibility factors than direct causes. However, there is a significant gap in the research on other chloride channels, particularly ClC-Ka, ClC-Kb, ClC-5, and ClC-7, whose roles in epilepsy remain underexplored. Future research should focus on these channels to better understand their contribution to the pathophysiology of epilepsy. The incorporation of genetic tests for chloride channel variants in clinical practice could provide valuable insight into the aetiology of epilepsy, leading to improved diagnostic and therapeutic strategies for affected individuals.

Deregulated ion channels contribute to RHOBTB2-associated developmental and epileptic encephalopathy

While de novo missense variants in the BTB domains of atypical RhoGTPase RHOBTB2 cause a severe developmental and epileptic encephalopathy, de novo missense variants in the GTPase domain or bi-allelic truncating variants are associated with more variable neurodevelopmental and seizure phenotypes. Apart from the observation of RHOBTB2 abundance resulting from BTB-domain variants and increased seizure susceptibility in Drosophila overexpressing RhoBTB, our knowledge on RHOBTB2-related pathomechanisms is limited. We now found enrichment for ion channels among the differentially expressed genes from RNA-Seq on fly heads overexpressing RhoBTB. Subsequent genetic interaction experiments confirmed a functional link between RhoBTB and paralytic, the orthologue of human sodium channels, including epilepsy associated SCN1A, in vivo. We then performed patch-clamp recordings on mature neurons differentiated from human induced pluripotent stem cells with either homozygous frameshifts or patient-specific heterozygous missense variants in the GTPase or the BTB domains. This revealed significantly altered neuronal activity and excitability resulting from BTB domain variants but not from GTPase domain variants or upon complete loss of RHOBTB2. Our study indicates a role of deregulated ion channels in the pathogenesis of RHOBTB2-related developmental and epileptic encephalopathy and points to specific pathomechanisms underlying the observed genotype-phenotype correlations regarding variant zygosity, location and nature.

Two pores instead of one: Gating pore current and the electrical leak in autism and epilepsy

Imagine the brain as a dynamic city, where countless vehicles traverse major arterial roads and branching side streets. The smooth traffic flow depends on a balance between excitatory neurons, which act as main roads encouraging vehicles to move forward, and inhibitory neurons, represented by branching side streets that regulate and control the traffic flow back onto the main route. Both systems work in tandem to maintain efficient operations, preventing gridlock or chaos. Zooming in further, the voltage-gated ion channels within neurons resemble traffic lights on arterial roads or side streets. Green means go, red means stop, and yellow signals caution. These channels regulate the flow of bioelectric signals, coordinating transitions between green, yellow, and red-analogous to an action potential. In excitatory neurons (major roads), voltage-gated sodium channels act as green lights, allowing sodium ions to flow in during depolarization. In contrast, voltage-gated potassium channels serve as yellow lights, eventually signaling red to terminate the action potential. In inhibitory neurons (side streets), sodium influx produces action potentials that ultimately control and limit traffic on the major roads. This analogy can be extended to describe neuropsychiatric and neurological disorders, such as autism spectrum disorder (ASD) and epilepsy, which arise from mutations in voltage-gated ion channels. These mutations alter the channels' ability to open and close properly, disrupting the timing and duration of red, yellow and green signals and impairing traffic flow. Now, picture yourself on a major arterial road with green and red flickering simultaneously. Such a disastrous scenario could lead to even more dangerous outcomes, with cars moving when they should stop or stopping when they should move. This specific analogy illustrates a key feature of certain mutations in voltage-gated ion channels that result in the gating pore current (Igp), a secondary pore that leaks electrical current. This mini-review focuses on Igp caused by mutations in the gating charge residues of voltage-gated ion channels. We will discuss how Igp contributes to the pathophysiology of ASD and epilepsy and explore therapeutic strategies targeting this mechanism.

Using Immunoliposomes as Carriers to Enhance the Therapeutic Effectiveness of Macamide N-3-Methoxybenzyl-Linoleamide

BACKGROUND/OBJECTIVES

Epilepsy is one of the most common chronic neurological disorders, characterized by alterations in neuronal electrical activity that result in recurrent seizures and involuntary body movements. Anticonvulsants are the primary treatment for this condition, helping patients improve their quality of life. However, the development of new drugs with fewer side effects and greater economic accessibility remains a key focus in nanomedicine. Macamides, secondary metabolites derived from Maca (Lepidium meyenii), represent a promising class of novel drugs with diverse therapeutic applications, particularly in the treatment of neurological disorders.

METHODS

In this study, we optimized the potential of the macamide N-3-methoxybenzyl-linoleamide (3-MBL) as an anticonvulsant agent through its encapsulation in PEGylated liposomes conjugated with OX26 F(ab')2 fragments.

RESULTS

These immunoliposomes exhibited a size of 120.52 ± 9.46 nm and a zeta potential of -8.57 ± 0.80 mV. Furthermore, in vivo tests using a pilocarpine-induced status epilepticus model revealed that the immunoliposomes provided greater efficacy against epileptic seizures compared to the free form of N-3-methoxybenzyl-linoleamide at the same dose. Notably, the observed anticonvulsant effect was comparable to that of carbamazepine, a traditional FDA-approved antiepileptic drug.

CONCLUSIONS

This pioneering work employs liposomal nanocarriers to deliver macamides to the brain, aiming to set a new standard for the use of modified liposomes in anticonvulsant epilepsy treatment.

Current development in sulfonamide derivatives to enable CNS-drug discovery

The encouraging therapeutic potential of sulfonamide-based derivatives has been unraveled by breakthrough discovery of Paul Ehrlich, who pointed out the possibility of fighting microbes with chemicals. Over the decades, the utility of sulfonamides has expanded beyond antimicrobial agents, revealing their usefulness in many areas of pharmacotherapy, including the treatment of central nervous system (CNS) diseases. Through a detailed analysis of preclinical and clinical data, we identify key sulfonamide-based compounds that have demonstrated significant CNS activity. We also discuss the challenges in the development of sulfonamide derivatives as enzyme/ion channel inhibitors or receptor ligands for CNS applications, describing their mode of action and therapeutic significance. This is followed by the characteristics of pharmacological targets, structure-activity relationships, ADMET properties, efficacy in experimental animal models, and outcomes from clinical trials. Overall, the versatile nature of arylsulfonamides makes them a valuable motif in drug discovery, offering diverse opportunities for the development of novel agents for treating CNS disorders.

Genetic and non-genetic factors influencing the therapeutic response of valproic acid in pediatric epileptic patients

AIMS

Considerable inter-individual variability in the efficacy of valproic acid (VPA) has been reported, with approximately 20-45% of patients failing to achieve satisfactory seizure control after VPA monotherapy. The aim of this study was to investigate the influence of non-genetic and genetic factors on 12-month VPA-response in a cohort of 194 pediatric patients.

MATERIALS & METHODS

Trough concentrations were determined, and a panel of 48 variants located in pharmacokinetic and pharmacodynamic gene were genotyped.

RESULTS

Aetiology was highlighted as a significant factor for the response to VPA. Specifically, patients with idiopathic epilepsy demonstrated poorer 12-month outcomes (p < 0.001). Trough VPA concentrations did not significantly affect outcomes. Marginal association was found between VPA efficacy and the following genetic variants: GABRA1 rs10068980 (p = 0.02), SLC16A1 rs7169 (p = 0.02), ABCC2 rs1885301 (p = 0.092), ACADM rs1251079 (p = 0.061) and GABRA1 rs6883877 (p = 0.085), as indicated by Fisher's exact test. A significant cumulative effect of two genetic factors (GABRA1 rs10068980 and SLC16A1 rs7169) was observed after a multiple logistic analysis, with ORs of 2.828 (1.213, 6.594) and 4.066 (1.148,14.398), respectively.

CONCLUSION

Our study indicated that GABRA1 rs10068980 and SLC16A1 rs7169 might serve as potential biomarkers for predicting the 12-month VPA treatment outcomes in pediatric patients with epilepsy.

Transcriptomic analyses of human brains with Alzheimer's disease identified dysregulated epilepsy-causing genes

Background & Objective

Alzheimer's Disease (AD) patients at multiple stages of disease progression have a high prevalence of seizures. However, whether AD and epilepsy share pathophysiological changes remains poorly defined. In this study, we leveraged high-throughput transcriptomic data from sporadic AD cases at different stages of cognitive impairment across multiple independent cohorts and brain regions to examine the role of epilepsy-causing genes.

Methods

Epilepsy-causing genes were manually curated, and their expression levels were analyzed across bulk transcriptomic data from three AD cohorts and three brain regions. RNA-seq data from sporadic AD and control cases from the Knight ADRC, MSBB, and ROSMAP cohorts were processed and analyzed under the same analytical pipeline. An integrative clustering approach employing machine learning and multi-omics data was employed to identify molecularly defined profiles with different cognitive scores.

Results

We found several epilepsy-associated genes/pathways significantly dysregulated in a group of AD patients with more severe cognitive impairment. We observed 15 genes consistently downregulated across the three cohorts, including sodium and potassium channels, suggesting that these genes play fundamental roles in cognitive function or AD progression. Notably, we found 25 of these genes dysregulated in earlier stages of AD and become worse with AD progression.

Conclusion

Our findings showed that epilepsy-causing genes showed changes in the early and late stages of AD progression, suggesting that they might be playing a role in AD progression. We can not establish directionality or cause-effect with our findings. However, changes in the epilepsy-causing genes might underlie the presence of seizures in AD patients, which might be present before or concurrently with the initial stages of AD.

Identification and verification of autophagy-related gene signatures and their association with immune infiltration and drug responsiveness in epilepsy

Background

Epilepsy, a common neurological disorder, is characterized by susceptibility to recurrent seizures. Increasing evidence suggests that autophagy plays a crucial role in the initiation and progression of epilepsy. However, the precise mechanisms by which autophagy deficiencies involved in epileptogenesis are still not fully understood.

Methods

Two datasets of epilepsy (GSE143272 and GSE256068) were downloaded from the Gene Expression Omnibus (GEO) database. Differential expression genes (DEGs) analysis and weighted gene co-expression network analysis (WGCNA) were employed to screen for autophagy related differential expression genes (ARDEGs) in GSE143272 database. Subsequently, protein-protein interaction, transcription factors and miRNAs networks were constructed. Additionally, the functional enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were applied. The hub ARDEGs were identified through CytoHubba, followed by the LASSO analysis. The Immune Cell Abundance Identifier (ImmuCellAI) was used to estimate peripheral immune cells abundance of epilepsy. Furthermore, the expression level of hub ARDEGs were detected in patients treated with different epilepsy monotherapies to explore the role of autophagy in the responsiveness of antiepileptic drug therapy. Finally, the expression level of hub ARDEGs were further validated in hippocampus of GSE256068 to enhance the reliability of the results.

Results

Twenty ARDEGs in epilepsy were screened out by integrating DEGs and WGCNA analysis. KEGG enrichment analysis showed that the ARDEGs in epilepsy were not only involved in the autophagy, but also apoptosis, the NOD-like receptor signaling pathway, the neurotrophin signaling pathway, etc. Four hub ARDEGs (PIK3R1, TRIM21, TRIM22, and ITPR3) were screened through integrating CytoHubba plug and LASSO analysis. The immune infiltration analysis showed that there was a significantly increased abundance of macrophages and a decreased abundance of CD4 and CD8 T cells, including Tr1, nTreg, Tfh, CD8 naïve, cytotoxic T cells and effector memory T cells in the epilepsy group. Furthermore, the hub ARDEGs were significantly correlated with the abundance of differential immune cells. In expression level validation and anti-epileptic drug responsiveness analysis, PIK3R1 and ITPR3 had significant differences in the hippocampus of patients with epilepsy. PIK3R1 expression level was found to be related with carbamazepine resistance.

Conclusion

This study elucidated the autophagy-related gene signatures in epilepsy and clarified their association with immune infiltration and anti-epileptic drug responsiveness, providing a novel target for future therapeutic interventions and disease markers in epilepsy.

Transmembrane Ion Channels: From Natural to Artificial Systems

Natural channel proteins allow the selective permeation of ions, water or other nutritious entities across bilayer membranes, facilitating various essential physiological functions in living systems. Inspired by nature, chemists endeavor to simulate the structural features and transport behaviors of channel proteins through biomimetic strategies. In this review, we start from introducing the inherent traits of channel proteins such as their crystal structures, functions and mechanisms. Subsequently, different kind of synthetic ion channels including their design principles, dynamic regulations and therapeutic applications were carefully reviewed. Finally, the potential challenges and opportunities in this research field were also carefully discussed. It is anticipated that this review could provide some inspiring ideas and future directions towards the construction of novel bionic ion channels with higher-level structures, properties, functions and practical applications.

Antiepileptic activity and potential mechanism of full-spectrum hemp extract

Epilepsy is the fourth most common neuropsychiatric disorder. Although the approval of Epidiolex has ignited hope for patients, there is still a large gap in the field of anti-seizure research. The effect and underlying mechanism of full-spectrum hemp extract (HE) remains unclear. Here this study investigated the anti-seizure effect of HE on seizure models. The results showed that HE significantly reduced seizure susceptibility and prolonged seizure latency with better pharmacokinetic performance compared to CBD. This article then further explored the anti-seizure active components and their possible mechanism in HE. The results indicated that cannabichromene (CBC) and cannabinol (CBN) were involved in the anti-seizure process, especially CBC showed a strong allosteric enhancement effects on CBD binding site of the GABAA receptor, which implied that the GABAA receptor seemed to be the primary anti-epileptic target of HE. This article not only presents the great potential of HE as a candidate for new anti-epileptic drugs with less psychoactive, but also provides a valuable contribution to subsequent mechanism research and drug development on epilepsy.Abstract: Epilepsy is the fourth most coneuropsychiatric disorder. Although the approval of Epidiolex has ignited hope for patients, there is still a large gap in the field of anti-seizure research. The effect and underlying mechanism of full-spectrum hemp extract remains unclear. Here this study investigated the anti-seizure effect of HE on seizure models. The results showed that HE significantly reduced seizure susceptibility and prolonged seizure latency with better pharmacokinetic performance compared to CBD. This article then further explored the anti-seizure active components and their possible mechanism in HE. The results indicated that cannabichromene and cannabinol were involved in the anti-seizure process, especially CBC showed a strong allosteric enhancement effects on CBD binding site of the GABAA receptor, which implied that the GABAA receptor seemed to be the primary anti-epileptic target of HE. This article not only presents the great potential of HE as a candidate for new anti-epileptic drugs with less psychoactive, but also provides a valuable contribution to subsequent mechanism research and drug development on epilepsy.

Chemogenetic Inhibition of Prefrontal Cortex Ameliorates Autism-Like Social Deficits and Absence-Like Seizures in a Gene-Trap Ash1l Haploinsufficiency Mouse Model

BACKGROUND

ASH1L (absent, small, or homeotic-like 1), a histone methyltransferase, has been identified as a high-risk gene for autism spectrum disorder (ASD). We previously showed that postnatal Ash1l severe deficiency in the prefrontal cortex (PFC) of male and female mice caused seizures. However, the synaptic mechanisms underlying autism-like social deficits and seizures need to be elucidated.

OBJECTIVE

The goal of this study is to characterize the behavioral deficits and reveal the synaptic mechanisms in an Ash1l haploinsufficiency mouse model using a targeted gene-trap knockout (gtKO) strategy.

METHOD

A series of behavioral tests were used to examine behavioral deficits. Electrophysiological and chemogenetic approaches were used to examine and manipulate the excitability of pyramidal neurons in the PFC of Ash1l+/GT mice.

RESULTS

Ash1l+/GT mice displayed social deficits, increased self-grooming, and cognitive impairments. Epileptiform discharges were found on electroencephalograms (EEGs) of Ash1l+/GT mice, indicating absence-like seizures. Ash1l haploinsufficiency increased the susceptibility for convulsive seizures when Ash1l+/GT mice were challenged by pentylenetetrazole (PTZ, a competitive GABAA receptor antagonist). Whole-cell patch-clamp recordings showed that Ash1l haploinsufficiency increased the excitability of pyramidal neurons in the PFC by altering intrinsic neuronal properties, enhancing glutamatergic synaptic transmission, and diminishing GABAergic synaptic inhibition. Chemogenetic inhibition of pyramidal neurons in the PFC of Ash1l+/GT mice ameliorated autism-like social deficits and abolished absence-like seizures.

CONCLUSIONS

We demonstrated that increased neural activity in the PFC contributed to the autism-like social deficits and absence-like seizures in Ash1l+/GT mice, which provides novel insights into the therapeutic strategies for patients with ASH1L-associated ASD and epilepsy.

HCN1 epilepsy: From genetics and mechanisms to precision therapies

Pathogenic variation in HCN1 is now an established cause of epilepsy and intellectual disability. Variation in HCN1 causes a spectrum of disease with a genotype-phenotype relationship emerging. De novo pathogenic variants that occur in the transmembrane domains of the channel typically cause a cation 'leak' that associates with severe developmental and epileptic encephalopathy (DEE). Genotype-phenotype associations for variants that fall outside of the transmembrane domains are less well established but do include milder forms of epilepsy that can be either de novo or inherited. HCN1 DEE mouse models have been generated which recapitulate the seizures and learning difficulties seen in human patients. These mice have also acted as powerful preclinical models which share pharmacoresponsiveness with human HCN1 DEE patients. Data from these mouse models support the conclusion that anti-seizure medications with sodium channel block as their primary mechanism of action should be used with caution in HCN1 DEE. Other comorbidities of HCN1 DEE including retinal dysfunction have also been modelled in HCN1 DEE mice, suggesting HCN1 variants can cause a dramatically reduced sensitivity to light with limited ability to process temporal information. Our understanding of the genetics and pathophysiological mechanisms underlying HCN1 epilepsy has progressed significantly and is already influencing therapy. However, more research effort is needed to fully understand the natural histories of HCN1 epilepsies and to develop precision therapeutic approaches.

Analysis of epilepsy-associated variants in HCN3 - Functional implications and clinical observations

OBJECTIVE

This case study investigates the role of hyperpolarization-activated, cyclic nucleotide-gated (HCN) ion channels, which are integral membrane proteins crucial for regulating neuronal excitability. HCN channels are composed of four subunits (HCN1-4), with HCN1, HCN2, and HCN4 previously linked to epilepsy. However, the role of the HCN3 in epileptogenesis remains underexplored.

METHODS

We recruited a cohort of 298 epilepsy patients to screen for genetic variants in the HCN3 (NM_020897.3) using Sanger sequencing. We identified rare variants and conducted functional assays to evaluate their pathogenicity.

RESULTS

We identified three rare heterozygous variants in HCN3: c.1370G > A (R457H), c.1982G > A (R661Q), and c.1982G > A(P630L). In vitro functional analyses demonstrated that these variants affected the expression level of HCN3 protein without altering its membrane localization. Whole-cell voltage-clamp experiments showed that two variants (R457H and R661Q) significantly reduced current density in cells, while P630L has no effect on ion channel current.

SIGNIFICANCE

Our findings suggest that the identified HCN3 genetic variants disrupt HCN ion channel function, highlighting HCN3 as a novel candidate gene involved in epileptic disorders. This expands the genetic landscape of epilepsy and provides new insights into its molecular underpinnings.

PLAIN LANGUAGE SUMMARY

Epilepsy is a brain disease that can be caused by mutations in specific genes. We found three rare variants in HCN3 gene in 298 patients with epilepsy, and two of the three mutations could be pathogenic and cause epilepsy and another one is single-nucleotide polymorphism, which could have no effect and no contribution to the development of epilepsy.

Preface: Special issue: "Ion channels and genetic epilepsy"

This preface introduces the Journal of Neurochemistry Special Issue on Advances in Epilepsy Research. Epilepsy is a devastating disease characterized by recurrent seizures. Despite the addition of numerous therapeutics over the last few decades epilepsy patients resistant to standard of care treatments remains stubbornly high. This highlights a clear unmet clinical need and the importance of new research into this disease. One major advance over the last two decades has been the recognition that genetic factors play a significant role in the underlying pathogenesis of epilepsy. Much of our insights into the pathogenic mechanisms underlying genetic epilepsy has come from research into genes that encode ion channels. In this issue, there are up-to-date reviews discussing epilepsy caused by variation in HCN channels, voltage-dependent sodium channels, voltage-dependent calcium channels, and GABAA receptors. The reviews highlight our understanding of the genotype-phenotype relationships and the identification of precision medicine approaches. Complimenting this is a review on metabolic aspects modulating ion channels in genetic disease. This issue also has fundamental research manuscripts investigating how currently approved drugs may rescue NMDA receptor dysfunction and how in vitro neuron cultures can be used to probe network scale deficits and drug impacts in SCN2A disease. Other primary data manuscripts include those focusing on metabolic therapies, gut microbiota, and new in vivo screening tools for identifying novel anti-seizure drugs. Collectively, manuscripts published as part of this edition highlight recent research gains, especially in our understanding of genetic causes of epilepsy involving ion channels.

Unveiling the role of histone deacetylases in neurological diseases: focus on epilepsy

Epilepsy remains a prevalent chronic neurological disease that is featured by aberrant, recurrent and hypersynchronous discharge of neurons and poses a great challenge to healthcare systems. Although several therapeutic interventions are successfully utilized for treating epilepsy, they can merely provide symptom relief but cannot exert disease-modifying effect. Therefore, it is of urgent need to explore other potential mechanism to develop a novel approach to delay the epileptic progression. Since approximately 30 years ago, histone deacetylases (HDACs), the versatile epigenetic regulators responsible for gene transcription via binding histones or non-histone substrates, have grabbed considerable attention in drug discovery. There are also substantial evidences supporting that aberrant expressions and/activities of HDAC isoforms are reported in epilepsy and HDAC inhibitors (HDACi) have been successfully utilized for therapeutic purposes in this condition. However, the specific mechanisms underlying the role of HDACs in epileptic progression have not been fully understood. Herein, we reviewed the basic information of HDACs, summarized the recent findings associated with the roles of diverse HDAC subunits in epilepsy and discussed the potential regulatory mechanisms by which HDACs affected the development of epilepsy. Additionally, we also provided a brief discussion on the potential of HDACs as promising therapeutic targets for epilepsy treatment, serving as a valuable reference for basic study and clinical translation in epilepsy field.

Human iPSC-derived microglia sense and dampen hyperexcitability of cortical neurons carrying the epilepsy-associated SCN2A-L1342P mutation

Neuronal hyperexcitability is a hallmark of epilepsy. It has been recently shown in rodent models of seizures that microglia, the brain's resident immune cells, can respond to and modulate neuronal excitability. However, how human microglia interact with human neurons to regulate hyperexcitability mediated by an epilepsy-causing genetic mutation found in patients is unknown. The SCN2A gene is responsible for encoding the voltage-gated sodium channel Nav1.2, one of the leading contributors to monogenic epilepsies. Previously, we demonstrated that the recurring Nav1.2-L1342P mutation leads to hyperexcitability in a male donor (KOLF2.1) hiPSC-derived cortical neuron model. Microglia originate from a different lineage (yolk sac) and are not naturally present in hiPSCs-derived neuronal cultures. To study how microglia respond to neurons carrying a disease-causing mutation and influence neuronal excitability, we established a co-culture model comprising hiPSC-derived neurons and microglia. We found that microglia display increased branch length and enhanced process-specific calcium signal when co-cultured with Nav1.2-L1342P neurons. Moreover, the presence of microglia significantly lowered the repetitive action potential firing and current density of sodium channels in neurons carrying the mutation. Additionally, we showed that co-culturing with microglia led to a reduction in sodium channel expression within the axon initial segment of Nav1.2-L1342P neurons. Furthermore, we demonstrated that Nav1.2-L1342P neurons release a higher amount of glutamate compared to control neurons. Our work thus reveals a critical role of human iPSCs-derived microglia in sensing and dampening hyperexcitability mediated by an epilepsy-causing mutation.Significance Statement Seizure studies in mouse models have highlighted the role of microglia in modulating neuronal activity, particularly in the promotion or suppression of seizures. However, a gap persists in comprehending the influence of human microglia on intrinsically hyperexcitable neurons carrying epilepsy-associated pathogenic mutations. This research addresses this gap by investigating human microglia and their impact on neuronal functions. Our findings demonstrate that microglia exhibit dynamic morphological alterations and calcium fluctuations in the presence of neurons carrying an epilepsy-associated SCN2A mutation. Furthermore, microglia suppressed the excitability of hyperexcitable neurons, suggesting a potential beneficial role. This study underscores the role of microglia in the regulation of abnormal neuronal activity, providing insights into therapeutic strategies for neurological conditions associated with hyperexcitability.

WONOEP appraisal: Genetic insights into early onset epilepsies

Early onset epilepsies occur in newborns and infants, and to date, genetic aberrations and variants have been identified in approximately one quarter of all patients. With technological sequencing advances and ongoing research, the genetic diagnostic yield for specific seizure disorders and epilepsies is expected to increase. Genetic variants associated with epilepsy include chromosomal abnormalities and rearrangements of various sizes as well as single gene variants. Among these variants, a distinction can be made between germline and somatic, with the latter being increasingly identified in epilepsies with focal cortical malformations in recent years. The identification of the underlying genetic mechanisms of epilepsy syndromes not only revolutionizes the diagnostic schemes but also leads to a better understanding of the diseases and their interrelationships, ultimately providing new opportunities for therapeutic targeting. At the XVI Workshop on Neurobiology of Epilepsy (WONOEP 2022, Talloires, France, July 2022), various etiologies, research models, and mechanisms of genetic early onset epilepsies were presented and discussed.

Cannabichromene from full-spectrum hemp extract exerts acute anti-seizure effects through allosteric activation of GABAA receptors

The approval of Epidiolex, an anti-epileptic drug containing cannabidiol (CBD) as its active component, has brought hope to patients with refractory epilepsy. However, the anti-seizure effect of full-spectrum hemp extract (HE), a CBD-enriched hemp oil, remains unclear. In this study, we investigated the anti-seizure effect of HE using drug-induced seizure models. Our findings revealed that HE significantly reduced seizure susceptibility comparable to CBD at the same doses. Moreover, we explored the pharmacokinetic properties of CBD in HE and observed improved characteristics such as faster oral absorption, enhanced brain distribution, and slower elimination. We further assessed the anti-seizure effects of the other five main non-addictive components in HE. Among these components, cannabichromene (CBC) and cannabinol (CBN) showed significant anti-seizure effects. To gain insights into the mechanisms of CBC and CBN, we investigated their allosteric modulation on the GABAA receptor. Our results revealed that CBC enhanced GABA-induced currents in both Xenopus laevis oocytes and mouse primary cortical neurons. Additionally, we identified V436 in the β2 subunit of the GABAA receptor as a critical binding site for CBC. These findings provide compelling evidence for the anti-seizure activities of HE and shed light on its underlying mechanisms. Our study provides insights into the broader therapeutic potential of hemp extracts and suggests their possible development as anti-seizure treatments.

Voltage-gated ion channels in epilepsies: circuit dysfunctions and treatments

Epileptic encephalopathies are generally considered to be functional disruptions in the balance between neural excitation and inhibition. Excitatory and inhibitory voltage-gated ion channels are key targets of antiepileptic drugs, playing a critical role in regulating neuronal excitation and synaptic transmission. Recent research has highlighted the significance of ion channels in various aspects of epilepsy, including presynaptic neurotransmitter release, intrinsic neuronal excitability, and neural synchrony. Genetic alterations in excitatory and inhibitory ion channels within principal neurons and in inhibitory interneurons have also been identified as key contributors to the development of epilepsies. We review these recent studies and shed light on the bidirectional relationship between epilepsy and neuronal excitability and the latest advancements in pharmacological therapeutics targeting ion channels for epilepsy treatment.

Therapeutic potential of ketamine in management of epilepsy: Clinical implications and mechanistic insights

Epilepsy, a widespread neurological disorder, affects approximately 50 million people worldwide. This disorder is typified by recurring seizures due to abnormal neuron communication in the brain. The seizures can lead to severe ischemia and hypoxia, potentially threatening patients' lives. However, with proper diagnosis and treatment, up to 70 % of patients can live without seizures. The causes of epilepsy are complex and multifactorial, encompassing genetic abnormalities, structural brain anomalies, ion channel dysfunctions, neurotransmitter imbalances, neuroinflammation, and immune system involvement. These factors collectively disrupt the crucial balance between excitation and inhibition within the brain, leading to epileptic seizures. The management of treatment-resistant epilepsy remains a considerable challenge, necessitating innovative therapeutic approaches. Among emerging potential treatments, ketamine-a drug traditionally employed for anesthesia and depression-has demonstrated efficacy in reducing seizures. It is noteworthy that, independent of its anti-epileptic effects, ketamine has been found to improve the balance between excitatory and inhibitory (E/I) activities in the brain. The balance is crucial for maintaining normal neural function, and its disruption is widely considered a key driver of epileptic seizures. By acting on N-methyl-D-aspartate (NMDA) receptors and other potential mechanisms, ketamine may regulate neuronal excitability, reduce excessive synchronized neural activity, and counteract epileptic seizures. This positive impact on E/I balance reinforces the potential of ketamine as a promising drug for treating epilepsy, especially in patients who are insensitive to traditional anti-epileptic drugs. This review aims to consolidate the current understanding of ketamine's therapeutic role in epilepsy. It will focus its impact on neuronal excitability and synaptic plasticity, its neuroprotective qualities, and elucidate the drug's potential mechanisms of action in treating epilepsy. By scrutinizing ketamine's impact and mechanisms in various types of epilepsy, we aspire to contribute to a more comprehensive and holistic approach to epilepsy management.

Voltage-Gated Ion Channel Compensatory Effect in DEE: Implications for Future Therapies

Developmental and Epileptic Encephalopathies (DEEs) represent a clinically and genetically heterogeneous group of rare and severe epilepsies. DEEs commonly begin early in infancy with frequent seizures of various types associated with intellectual disability and leading to a neurodevelopmental delay or regression. Disease-causing genomic variants have been identified in numerous genes and are implicated in over 100 types of DEEs. In this context, genes encoding voltage-gated ion channels (VGCs) play a significant role, and part of the large phenotypic variability observed in DEE patients carrying VGC mutations could be explained by the presence of genetic modifier alleles that can compensate for these mutations. This review will focus on the current knowledge of the compensatory effect of DEE-associated voltage-gated ion channels and their therapeutic implications in DEE. We will enter into detailed considerations regarding the sodium channels SCN1A, SCN2A, and SCN8A; the potassium channels KCNA1, KCNQ2, and KCNT1; and the calcium channels CACNA1A and CACNA1G.

Alterations in DNA 5-hydroxymethylation patterns in the hippocampus of an experimental model of chronic epilepsy

Temporal lobe epilepsy (TLE) is a type of focal epilepsy characterized by spontaneous recurrent seizures originating from the hippocampus. The epigenetic reprogramming hypothesis of epileptogenesis suggests that the development of TLE is associated with alterations in gene transcription changes resulting in a hyperexcitable network in TLE. DNA 5-methylcytosine (5-mC) is an epigenetic mechanism that has been associated with chronic epilepsy. However, the contribution of 5-hydroxymethylcytosine (5-hmC), a product of 5-mC demethylation by the Ten-Eleven Translocation (TET) family proteins in chronic TLE is poorly understood. 5-hmC is abundant in the brain and acts as a stable epigenetic mark altering gene expression through several mechanisms. Here, we found that the levels of bulk DNA 5-hmC but not 5-mC were significantly reduced in the hippocampus of human TLE patients and in the kainic acid (KA) TLE rat model. Using 5-hmC hMeDIP-sequencing, we characterized 5-hmC distribution across the genome and found bidirectional regulation of 5-hmC at intergenic regions within gene bodies. We found that hypohydroxymethylated 5-hmC intergenic regions were associated with several epilepsy-related genes, including Gal, SV2, and Kcnj11 and hyperdroxymethylation 5-hmC intergenic regions were associated with Gad65, TLR4, and Bdnf gene expression. Mechanistically, Tet1 knockdown in the hippocampus was sufficient to decrease 5-hmC levels and increase seizure susceptibility following KA administration. In contrast, Tet1 overexpression in the hippocampus resulted in increased 5-hmC levels associated with improved seizure resiliency in response to KA. These findings suggest an important role for 5-hmC as an epigenetic regulator of epilepsy that can be manipulated to influence seizure outcomes.

Research progress of epileptic seizure prediction methods based on EEG

At present, at least 30% of refractory epilepsy patients in the world cannot be effectively controlled and treated. The suddenness and unpredictability of seizures greatly affect the physical and mental health and even the life safety of patients, and the realization of early prediction of seizures and the adoption of interventions are of great significance to the improvement of patients' quality of life. In this paper, we firstly introduce the design process of EEG-based seizure prediction methods, introduce several databases commonly used in the research, and summarize the commonly used methods in pre-processing, feature extraction, classification and identification, and post-processing. Then, based on scalp EEG and intracranial EEG respectively, we reviewed the current status of epileptic seizure prediction research from five commonly used feature analysis methods, and make a comprehensive evaluation of both. Finally, this paper describes the reasons why the current algorithms cannot be applied to the clinic, summarizes their limitations, and gives corresponding suggestions, aiming to provide improvement directions for subsequent research. In addition, deep learning algorithms have emerged in recent years, and this paper also compares the advantages and disadvantages of deep learning algorithms with traditional machine learning methods, in the hope of providing researchers with new technologies and new ideas and making significant breakthroughs in the field of epileptic seizure prediction.

Exome sequencing of 20,979 individuals with epilepsy reveals shared and distinct ultra-rare genetic risk across disorder subtypes

Identifying genetic risk factors for highly heterogeneous disorders like epilepsy remains challenging. Here, we present the largest whole-exome sequencing study of epilepsy to date, with >54,000 human exomes, comprising 20,979 deeply phenotyped patients from multiple genetic ancestry groups with diverse epilepsy subtypes and 33,444 controls, to investigate rare variants that confer disease risk. These analyses implicate seven individual genes, three gene sets, and four copy number variants at exome-wide significance. Genes encoding ion channels show strong association with multiple epilepsy subtypes, including epileptic encephalopathies, generalized and focal epilepsies, while most other gene discoveries are subtype-specific, highlighting distinct genetic contributions to different epilepsies. Combining results from rare single nucleotide/short indel-, copy number-, and common variants, we offer an expanded view of the genetic architecture of epilepsy, with growing evidence of convergence among different genetic risk loci on the same genes. Top candidate genes are enriched for roles in synaptic transmission and neuronal excitability, particularly postnatally and in the neocortex. We also identify shared rare variant risk between epilepsy and other neurodevelopmental disorders. Our data can be accessed via an interactive browser, hopefully facilitating diagnostic efforts and accelerating the development of follow-up studies.

Structural insights into the allosteric effects of the antiepileptic drug topiramate on the CaV2.3 channel

The R-type voltage-gated calcium channel CaV2.3 is predominantly located in the presynapse and is implicated in distinct types of epileptic seizures. It has consequently emerged as a molecular target in seizure treatment. Here, we determined the cryo-EM structure of the CaV2.3-α2δ1-β1 complex in the topiramate-bound state at a 3.0 Å resolution. We provide a snapshot of the binding site of topiramate, a widely prescribed antiepileptic drug, on a voltage-gated ion channel. The binding site is located at an intracellular juxtamembrane hydrophilic cavity. Further structural analysis revealed that topiramate may allosterically facilitate channel inactivation. These findings provide fundamental insights into the mechanism underlying the inhibitory effect of topiramate on CaV and NaV channels, elucidating a previously unseen modulator binding site and thus pointing toward a route for the development of new drugs.

WONOEP appraisal: Modeling early onset epilepsies

Epilepsy has a peak incidence during the neonatal to early childhood period. These early onset epilepsies may be severe conditions frequently associated with comorbidities such as developmental deficits and intellectual disability and, in a significant percentage of patients, may be medication-resistant. The use of adult rodent models in the exploration of mechanisms and treatments for early life epilepsies is challenging, as it ignores significant age-specific developmental differences. More recently, models developed in immature animals, such as rodent pups, or in three-dimensional organoids may more closely model aspects of the immature brain and could result in more translatable findings. Although models are not perfect, they may offer a more controlled screening platform in studies of mechanisms and treatments, which cannot be done in pediatric patient cohorts. On the other hand, more simplified models with higher throughput capacities are required to deal with the large number of epilepsy candidate genes and the need for new treatment options. Therefore, a combination of different modeling approaches will be beneficial in addressing the unmet needs of pediatric epilepsy patients. In this review, we summarize the discussions on this topic that occurred during the XVI Workshop on Neurobiology of Epilepsy, organized in 2022 by the Neurobiology Commission of the International League Against Epilepsy. We provide an overview of selected models of early onset epilepsies, discussing their advantages and disadvantages. Heterologous expression models provide initial functional insights, and zebrafish, rodent models, and brain organoids present increasingly complex platforms for modeling and validating epilepsy-related phenomena. Together, these models offer valuable insights into early onset epilepsies and accelerate hypothesis generation and therapy discovery.

A randomized, double-blind, placebo-controlled, dose-escalating phase IIa trial to evaluate the safety, tolerability, efficacy, and pharmacokinetics of multiple oral doses of Pynegabine tablets as add-on therapy in patients with focal epilepsy

AIMS

This study aims to investigate the safety, tolerability, efficacy, and pharmacokinetics of Pynegabine as an add-on therapy in the treatment of focal epilepsy.

METHODOLOGY

This is a protocol phase-IIa, randomized, double-blinded, placebo-controlled, multicenter study in patients with focal epilepsy from multiple centers in China who have been treated with at least 2 ASMs without effective control. The study involves an 8-week run-in period with stable use of previous medications. Patients are then randomized to receive either Pynegabine or a placebo. Sentinel administration is performed initially, and subsequent patients are randomized based on safety assessments. Three dose cohorts (15, 20, and 25 mg/d) are established. Efficacy is assessed through various measures, including seizure frequency, CGI score, PGI score, HAMA score, HAMD score, MoCA scale score, QOLIE-31 scale score, and 12 h-EEG score. Safety evaluations, PK blood samples, concomitant medications, and adverse events are also recorded.

CONCLUSION

Data from the study will be used to evaluate the safety, tolerability, efficacy, and pharmacokinetics of Pynegabine tablets as add-on therapy for focal epilepsy.

New epilepsy therapies in development

Epilepsy is a common brain disorder, characterized by spontaneous recurrent seizures, with associated neuropsychiatric and cognitive comorbidities and increased mortality. Although people at risk can often be identified, interventions to prevent the development of the disorder are not available. Moreover, in at least 30% of patients, epilepsy cannot be controlled by current antiseizure medications (ASMs). As a result of considerable progress in epilepsy genetics and the development of novel disease models, drug screening technologies and innovative therapeutic modalities over the past 10 years, more than 200 novel epilepsy therapies are currently in the preclinical or clinical pipeline, including many treatments that act by new mechanisms. Assisted by diagnostic and predictive biomarkers, the treatment of epilepsy is undergoing paradigm shifts from symptom-only ASMs to disease prevention, and from broad trial-and-error treatments for seizures in general to mechanism-based treatments for specific epilepsy syndromes. In this Review, we assess recent progress in ASM development and outline future directions for the development of new therapies for the treatment and prevention of epilepsy.

A novel isoquinoline alkaloid HJ-69 isolated from Zanthoxylum bungeanum attenuates inflammatory pain by inhibiting voltage-gated sodium and potassium channels

ETHNOPHARMACOLOGY RELEVANCE

Zanthoxylum bungeanum Maxim. (Z. bungeanum), a member of the Rutaceae family, has a rich history of traditional use in Asia for treating arthritis and toothache conditions. As characteristic chemical components, numerous kinds of alkaloids have been extracted from plants and their diverse biological activities have been reported. However, research on the isoquinoline alkaloid, a specific type of alkaloids, in Z. bungeanum was scarce.

AIM OF THE STUDY

The study aimed to isolate a novel isoquinoline alkaloid from Z. bungeanum and explore its pharmacological activity in vitro and analgesic activity in vivo.

MATERIALS AND METHODS

Isoquinoline alkaloid isolation and identification from Z. bungeanum were conducted using chromatographic and spectroscopic methods. The whole-cell patch-clamp technique was applied to assess its impact on neuronal excitability, and endogenous voltage-gated potassium (Kv) and sodium (Nav) currents in acutely isolated mouse small-diameter dorsal root ganglion (DRG) neurons. Its inhibitory impacts on channels were further validated with HEK293 cells stably expressing Nav1.7 and Nav1.8, and Chinese hamster ovary (CHO) cells transiently expressing Kv2.1. The formalin inflammatory pain model was utilized to evaluate the potential analgesic activity in vivo.

RESULTS

A novel isoquinoline alkaloid named HJ-69 (N-13-(3-methoxyprop-1-yl)rutaecarpine) was isolated and identified from Z. bungeanum for the first time. HJ-69 significantly suppressed the firing frequency and amplitudes of action potentials in DRG neurons. Consistently, it state-dependently inhibited endogenous Nav currents of DRG neurons, with half maximal inhibitory concentration (IC50) values of 13.06 ± 2.06 μM and 30.19 ± 2.07 μM for the inactivated and resting states, respectively. HJ-69 significantly suppressed potassium currents in DRG neurons, which notably inhibited the delayed rectifier potassium (IK) currents (IC50 = 6.95 ± 1.29 μM) and slightly affected the transient outward potassium (IA) currents (IC50 = 523.50 ± 39.16 μM). Furtherly, HJ-69 exhibited similar potencies on heterologously expressed Nav1.7, Nav1.8, and Kv2.1 channels, which correspondingly represent the main components in neurons. Notably, intraperitoneal administration of 30 mg/kg and 100 mg/kg HJ-69 significantly alleviated pain behaviors in the mouse inflammatory pain model induced by formalin.

CONCLUSION

The study concluded that HJ-69 is a novel and active isoquinoline alkaloid, and the inhibition of Nav and Kv channels contributes to its analgesic activity. HJ-69 may be a promising prototype for future analgesic drug discovery based on the isoquinoline alkaloid.

Presynaptic antiseizure medications - basic mechanisms and clues for their rational combinations

Among clinically highly efficient antiseizure medications (ASMs) there are modifiers of the presynaptic release machinery. Of them, levetiracetam and brivaracetam show a high affinity to the synaptic vesicle protein type 2 A (SV2A), whereas pregabalin and gabapentin are selective ligands for the α2δ1 subunits of the voltage-gated calcium channels. In this paper, we present recent progress in understanding the significance of presynaptic release machinery in the neurochemical mechanisms of epilepsy and ASMs. Furthermore, we discuss whether the knowledge of the basic mechanisms of the presynaptically acting ASMs might help establish a rational polytherapy for drug-resistant epilepsy.

A Comprehensive Review on Current Insights Into Epileptic Encephalopathy: Pathogenesis and Therapeutic Strategies

Epileptic encephalopathy (EE) represents a challenging group of disorders characterized by severe epilepsy and significant cognitive, behavioral, and neurological impairments. This comprehensive review aims to elucidate the current insights into the pathogenesis and therapeutic strategies for these disorders. Pathogenesis involves a complex interplay of genetic factors, neurobiological mechanisms, and environmental influences that contribute to the severity and progression of symptoms. Clinical manifestations are diverse, encompassing various seizure types, cognitive and behavioral impairments, and developmental delays. Current therapeutic strategies include pharmacological treatments, nonpharmacological interventions, and emerging therapies such as gene and stem cell therapy. Despite advancements, significant challenges and limitations remain, highlighting the need for ongoing research and innovation. This review synthesizes existing knowledge, identifies research gaps, and proposes future directions, emphasizing the potential for personalized medicine to improve patient outcomes and quality of life.

Deciphering the Complexities of Sodium Voltage-Gated Channel Alpha Subunit 1 (SCN1A) Mutation: A Case of Intractable Epilepsy in a Five-and-a-Half-Month-Old Male

If the sodium voltage-gated channel alpha subunit 1 (SCN1A) gene, which encodes Nav1.1 protein, undergoes pathological mutation, it results in a wide range of epileptic syndrome, including febrile seizure, genetic epilepsy with febrile seizure plus (GEFS+), and developmental and epileptic encephalopathy (DEE), including Dravet syndrome. We present the case of a five-and-a-half-month-old boy with SCN1A gene-related epileptic seizures, starting as focal seizures and progressing to generalized tonic-clonic seizures. Despite treating the seizures with multiple antiepileptic drugs, including phenytoin, sodium valproate, levetiracetam, perampanel, and clobazam, it was very difficult to control the seizures, and genetic testing was suggested. The SCN1A mutation leads to either loss of function, including GEFS+ and Dravet syndrome, or gain of function, including familial hemiplegic migraine type 3. The case emphasizes the importance of genetic testing in refractory epilepsy management to provide medical strategies for the diagnosis. It focuses on the difficulties faced in diagnostic and treatment strategies for the management of SCN1A-related epilepsy. It emphasizes the importance of monitoring and personalized treatment strategies to reduce the incidence of refractory epilepsy.

KCNT1 Channel Blockers: A Medicinal Chemistry Perspective

Potassium channels have recently emerged as suitable target for the treatment of epileptic diseases. Among potassium channels, KCNT1 channels are the most widely characterized as responsible for several epileptic and developmental encephalopathies. Nevertheless, the medicinal chemistry of KCNT1 blockers is underdeveloped so far. In the present review, we describe and analyse the papers addressing the issue of KCNT1 blockers' development and identification, also evidencing the pros and the cons of the scientific approaches therein described. After a short introduction describing the epileptic diseases and the structure-function of potassium channels, we provide an extensive overview of the chemotypes described so far as KCNT1 blockers, and the scientific approaches used for their identification.

Retigabine and gabapentin restore channel function and neuronal firing in a cellular model of an epilepsy-associated dominant-negative KCNQ5 variant

KCNQ5 encodes the voltage-gated potassium channel KV7.5, a member of the KV7 channel family, which conducts the M-current. This current is a potent regulator of neuronal excitability by regulating membrane potential in the subthreshold range of action potentials and mediating the medium and slow afterhyperpolarization. Recently, we have identified five loss-of-function variants in KCNQ5 in patients with genetic generalized epilepsy. Using the most severe dominant-negative variant (R359C), we set out to investigate pharmacological therapeutic intervention by KV7 channel openers on channel function and neuronal firing. Retigabine and gabapentin increased R359C-derived M-current amplitudes in HEK cells expressing homomeric or heteromeric mutant KV7.5 channels. Retigabine was most effective in restoring K+ currents. Ten μM retigabine was sufficient to reach the level of WT currents without retigabine, whereas 100 μM of gabapentin showed less than half of this effect and application of 50 μM ZnCl2 only significantly increased M-current amplitude in heteromeric channels. Overexpression of KV7.5-WT potently inhibited neuronal firing by increasing the M-current, whereas R359C overexpression had the opposite effect and additionally decreased the medium afterhyperpolarization current. Both aforementioned drugs and Zn2+ reversed the effect of R359C expression by reducing firing to nearly normal levels at high current injections. Our study shows that a dominant-negative variant with a complete loss-of-function in KV7.5 leads to largely increased neuronal firing which may explain a neuronal hyperexcitability in patients. KV7 channel openers, such as retigabine or gabapentin, could be treatment options for patients currently displaying pharmacoresistant epilepsy and carrying loss-of-function variants in KCNQ5.

Potassium channel-related epilepsy: Pathogenesis and clinical features

Variants in potassium channel-related genes are one of the most important mechanisms underlying abnormal neuronal excitation and disturbances in the cellular resting membrane potential. These variants can cause different forms of epilepsy, which can seriously affect the physical and mental health of patients, especially those with refractory epilepsy or status epilepticus, which are common among pediatric patients and are potentially life-threatening. Variants in potassium ion channel-related genes have been reported in few studies; however, to our knowledge, no systematic review has been published. This study aimed to summarize the epilepsy phenotypes, functional studies, and pharmacological advances associated with different potassium channel gene variants to assist clinical practitioners and drug development teams to develop evidence-based medicine and guide research strategies. PubMed and Google Scholar were searched for relevant literature on potassium channel-related epilepsy reported in the past 5-10 years. Various common potassium ion channel gene variants can lead to heterogeneous epilepsy phenotypes, and functional effects can result from gene deletions and compound effects. Administration of select anti-seizure medications is the primary treatment for this type of epilepsy. Most patients are refractory to anti-seizure medications, and some novel anti-seizure medications have been found to improve seizures. Use of targeted drugs to correct aberrant channel function based on the type of potassium channel gene variant can be used as an evidence-based pathway to achieve precise and individualized treatment for children with epilepsy. PLAIN LANGUAGE SUMMARY: In this article, the pathogenesis and clinical characteristics of epilepsy caused by different types of potassium channel gene variants are reviewed in the light of the latest research literature at home and abroad, with the expectation of providing a certain theoretical basis for the diagnosis and treatment of children with this type of disease.

Analysis of the action mechanisms and targets of herbal anticonvulsants highlights opportunities for therapeutic engagement with refractory epilepsy

Epilepsy is a neurological disorder characterized by spontaneous and recurring seizures. It poses significant therapeutic challenges due to diverse etiology, pathobiology, and pharmacotherapy-resistant variants. The anticonvulsive effects of herbal leads with biocompatibility and toxicity considerations have attracted much interest, inspiring mechanistic analysis with the view of their use for engagement of new targets and combination with antiseizure pharmacotherapies. This article presents a comprehensive overview of the key molecular players and putative action mechanisms of the most common antiepileptic herbals demonstrated in tissue culture and preclinical models. From the review of the literature, it emerges that their effects are mediated via five distinct mechanisms: (1) reduction of membrane excitability through inhibition of cation channels, (2) improvement of mitochondrial functions with antioxidant effects, (3) enhancement in synaptic transmission mediated by GABAA receptors, (4) improvement of immune response with anti-inflammatory action, and (5) suppression of protein synthesis and metabolism. While some of the primary targets and action mechanisms of herbal anticonvulsants (1, 3) are shared with antiseizure pharmacotherapies, herbal leads also engage with distinct mechanisms (2, 4, and 5), suggesting new drug targets and opportunities for their integration with antiseizure medications. Addressing outstanding questions through research and in silico modeling should facilitate the future use of herbals as auxiliary therapy in epilepsy and guide the development of treatment of pharmacoresistant seizures through rigorous trials and regulatory approval.

The effect of ferroptosis-related mitochondrial dysfunction in the development of temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is the most common form of epileptic syndrome. It has been established that due to its complex pathogenesis, a considerable proportion of TLE patients often progress to drug-resistant epilepsy. Ferroptosis has emerged as an important neuronal death mechanism in TLE, which is primarily influenced by lipid accumulation and oxidative stress. In previous studies of ferroptosis, more attention has been focused on the impact of changes in the levels of proteins related to the redox equilibrium and signaling pathways on epileptic seizures. However, it is worth noting that the oxidative-reduction changes in different organelles may have different pathophysiological significance in the process of ferroptosis-related diseases. Mitochondria, as a key organelle involved in ferroptosis, its structural damage and functional impairment can lead to energy metabolism disorders and disruption of the excitatory inhibitory balance, significantly increasing the susceptibility to epileptic seizures. Therefore, secondary mitochondrial dysfunction in the process of ferroptosis could play a crucial role in TLE pathogenesis. This review focuses on ferroptosis and mitochondria, discussing the pathogenic role of ferroptosis-related mitochondrial dysfunction in TLE, thus aiming to provide novel insights and potential implications of ferroptosis-related secondary mitochondrial dysfunction in epileptic seizures and to offer new insights for the precise exploration of ferroptosis-related therapeutic targets for TLE patients.

De novo variants in KCNJ3 are associated with early-onset epilepsy

BACKGROUND

KCNJ3 encodes a subunit of G-protein-coupled inwardly rectifying potassium channels, which are important for cellular excitability and inhibitory neurotransmission. However, the genetic basis of KCNJ3 in epilepsy has not been determined. This study aimed to identify the pathogenic KCNJ3 variants in patients with epilepsy.

METHODS

Trio exome sequencing was performed to determine potential variants of epilepsy. Individuals with KCNJ3 variants were recruited for this study. Detailed clinical information and genetic data were obtained and systematically reviewed. Whole-cell patch-clamp recordings were performed to evaluate the functional consequences of the identified variants.

RESULTS

Two de novo missense variants (c.998T>C (p.Leu333Ser) and c.938G>A (p. Arg313Gln)) in KCNJ3 were identified in two unrelated families with epilepsy. The variants were absent from the gnomAD database and were assumed to be damaging or probably damaging using multiple bioinformatics tools. They were both located in the C-terminal domain. The amino acid residues were highly conserved among various species. Clinically, the seizures occurred at a young age and were under control after combined treatment. Electrophysiological analysis revealed that the KCNJ3 Leu333Ser and Arg313Gln variants significantly compromised the current activities and exhibited loss-of-function (LOF) effects.

CONCLUSION

Our findings suggest that de novo LOF variants in KCNJ3 are associated with early-onset epilepsy. Genetic testing of KCNJ3 in patients with epilepsy may serve as a strategy for precision medicine.