Immune Challenges and Seizures: How Do Early Life Insults Influence Epileptogenesis?

Virus-Induced Epilepsy vs. Epilepsy Patients Acquiring Viral Infection: Unravelling the Complex Relationship for Precision Treatment

The intricate relationship between viruses and epilepsy involves a bidirectional interaction. Certain viruses can induce epilepsy by infecting the brain, leading to inflammation, damage, or abnormal electrical activity. Conversely, epilepsy patients may be more susceptible to viral infections due to factors, such as compromised immune systems, anticonvulsant drugs, or surgical interventions. Neuroinflammation, a common factor in both scenarios, exhibits onset, duration, intensity, and consequence variations. It can modulate epileptogenesis, increase seizure susceptibility, and impact anticonvulsant drug pharmacokinetics, immune system function, and brain physiology. Viral infections significantly impact the clinical management of epilepsy patients, necessitating a multidisciplinary approach encompassing diagnosis, prevention, and treatment of both conditions. We delved into the dual dynamics of viruses inducing epilepsy and epilepsy patients acquiring viruses, examining the unique features of each case. For virus-induced epilepsy, we specify virus types, elucidate mechanisms of epilepsy induction, emphasize neuroinflammation's impact, and analyze its effects on anticonvulsant drug pharmacokinetics. Conversely, in epilepsy patients acquiring viruses, we detail the acquired virus, its interaction with existing epilepsy, neuroinflammation effects, and changes in anticonvulsant drug pharmacokinetics. Understanding this interplay advances precision therapies for epilepsy during viral infections, providing mechanistic insights, identifying biomarkers and therapeutic targets, and supporting optimized dosing regimens. However, further studies are crucial to validate tools, discover new biomarkers and therapeutic targets, and evaluate targeted therapy safety and efficacy in diverse epilepsy and viral infection scenarios.

Clinical characteristics and associated factors of posttraumatic epilepsy after traumatic brain injury in children: A retrospective case-control study

BACKGROUND

Traumatic brain injury (TBI) affects approximately 69 million individuals annually, often resulting in well-documented complications such as epilepsy. Although numerous studies have been performed on posttraumatic epilepsy (PTE) in adults over the past decade, research on chronic consequences of TBI in children remains limited. Herein, we retrospectively assessed children who had experienced moderate to severe TBI to determine their clinical characteristics and identify associated factors associated with the development of PTE in the pediatric population.

METHODS

The study population comprised children aged 0-18 years who had experienced moderate to severe TBI and underwent treatment at the Children's Hospital of Chongqing Medical University between 2011 and 2021. They were categorized into two groups: the PTE group, comprising individuals diagnosed with PTE within a one-year follow-up period, and the nPTE group, consisting of those who did not develop PTE during the same timeframe. The primary objective was to investigate the clinical characteristics and identify related associated factors. The relationship between various clinical factors and the incidence of PTE was assessed through univariate and multivariate logistic regression.

RESULTS

A total of 132 patients were assessed. Most participants were male (65%) and the age distribution skewed towards younger children, with a median age of 41.0 months (interquartile range: 45.3). Upon their last clinical visit, 64 children (49%) were diagnosed with PTE. Notably, the first posttraumatic seizure predominantly occurred within the first week following the traumatic event. Further analyses revealed that increasing injury severity, as indicated by a lower Glasgow Coma Scale (GCS) score (odds ratio [OR]: 0.78, 95% confidence interval [CI]: 0.54-1.12, p= 0.018), a contusion load ≥3 (OR: 8.1, 95% CI: 2.3-28.9, p= 0.001), immediate posttraumatic seizures (IPTS) (OR: 8.9, 95% CI: 2.5-31.2, p < 0.001), and early posttraumatic seizures (EPTS) (OR: 54, 95% CI: 11-276, p < 0.001), were all significantly associated with a higher risk of developing PTE.

CONCLUSION

This study highlights that the onset of PTE was associated with the markers of injury severity or PTS and identified GCS scores, contusion loads of ≥3, IPTS, and EPTS as independent associated factors significantly associated with the development of PTE.

Viral Vector-Based Gene Therapy for Epilepsy: What Does the Future Hold?

In recent years, many pre-clinical studies have tested gene therapy approaches as possible treatments for epilepsy, following the idea that they may provide an alternative to conventional pharmacological and surgical options. Multiple gene therapy approaches have been developed, including those based on anti-sense oligonucleotides, RNA interference, and viral vectors. In this opinion article, we focus on translational issues related to viral vector-mediated gene therapy for epilepsy. Research has advanced dramatically in addressing issues like viral vector optimization, target identification, strategies of gene expression, editing or regulation, and safety. Some of these pre-clinically validated potential gene therapies are now being tested in clinical trials, in patients with genetic or focal forms of drug-resistant epilepsy. Here, we discuss the ongoing translational research and the advancements that are needed and expected in the near future. We then describe the clinical trials in the pipeline and the further challenges that will need to be addressed at the clinical and economic levels. Our optimistic view is that all these issues and challenges can be overcome, and that gene therapy approaches for epilepsy will soon become a clinical reality.

Perampanel increases seizure threshold in pentylenetetrazole-kindled mice and improves behavioral dysfunctions by modifying mRNA expression levels of BDNF/TrkB and inflammatory markers

Perampanel (PER), a novel 3rd-generation antiseizure drug that modulates altered post-synaptic glutamatergic storming by selectively inhibiting AMPA receptors, is recently approved to treat intractable forms of seizures. However, to date, presumably consequences of long-term PER therapy on the comorbid deleterious psychiatric disturbances and its correlation with neuroinflammatory parameters are not fully investigated in chronic models of epilepsy. Therefore, we investigated the real-time effect of PER on brain electroencephalographic (EEG) activity, behavioral alterations, redox balance, and relative mRNA expression in pentylenetetrazole (PTZ) induced kindling. Male BALB/c mice were pretreated with PER (0.125, 0.25, and 0.5 mg/kg) for 3 weeks and challenged with 11 injections of PTZ at the sub-threshold dose of 40 mg/kg every other day. vEEG from implanted cortical electrodes was monitored to elucidate seizure propagation and behavioral manifestations. Recorded EEG signals exhibited that PER 0.5 mg/kg pretreatment exceptionally impeded the onset of sharp epileptic spike-wave discharges and associated motor symptoms. Additionally, qEEG analysis showed that PER prevented alterations in absolute mean spectral power and reduced RMS amplitude of epileptogenic spikes vs PTZ control. Furthermore, our outcomes illustrated that PER dose-dependently attenuated PTZ-evoked anxiety-like behavior, memory deficits, and depressive-like behavior that was validated by a series of behavioral experiments. Moreover PER, significantly reduced lipid peroxidation, AChE, and increased levels of SOD and total thiol in the mice brain via AMPAR antagonism. Post-PTZ kindling provoked overstimulation of BDNF/TrkB signaling and increased release of pro-inflammatory cytokines that were reversed by PER with suppression of iNOS in brain immune cells. In conclusion, our findings highlight that PER might play an auspicious preventive role in the proepileptic transformation of brain circuits via suppression of BDNF/TrkB signaling and reduced transcriptional levels of neuroinflammatory markers leading to improvised epilepsy-induced neurobehavioral and neurochemical effects.

Differential gene expression profiling implicates altered network development in rat postnatal day 4 cortex following 4-Methylimidazole (4-MeI) induced maternal seizures

Compromised maternal health leading to maternal seizures can have adverse effects on the healthy development of offspring. This may be the result of inflammation, hypoxia-ischemia, and altered GABA signaling. The current study examined cortical tissue from F2b (2nd litter of the 2nd generation) postnatal day 4 (PND4) offspring of female Harlan SD rats chronically exposed to the seizuregenic compound, 4-Methylimidazole (0, 750, or 2500 ppm 4-MeI). Maternal seizures were evident only at 2500 ppm 4-MeI. GABA related gene expression as examined by qRT-PCR and whole genome microarray showed no indication of disrupted GABA or glutamatergic signaling. Canonical pathway hierarchical clustering and multi-omics combinatory genomic (CNet) plots of differentially expressed genes (DEG) showed alterations in genes associated with regulatory processes of cell development including neuronal differentiation and synaptogenesis. Functional enrichment analysis showed a similarity of cellular processes across the two exposure groups however, the genes comprising each cluster were primarily unique rather than shared and often showed different directionality. A dose-related induction of cytokine signaling was indicated however, pathways associated with individual cytokine signaling were not elevated, suggesting an alternative involvement of cytokine signaling. Pathways related to growth process and cell signaling showed a negative activation supporting an interpretation of disruption or delay in developmental processes at the 2500 ppm 4-MeI exposure level with maternal seizures. Thus, while GABA signaling was not altered as has been observed with maternal seizures, the pattern of DEG suggested a potential for alteration in neuronal network formation.

Seizure-induced increase in microglial cell population in the developing zebrafish brain

Epilepsy is a chronic brain disorder characterized by unprovoked and recurrent seizures, of which 60% are of unknown etiology. Recent studies implicate microglia in the pathophysiology of epilepsy. However, their role in this process, in particular following early-life seizures, remains poorly understood due in part to the lack of suitable experimental models allowing the in vivo imaging of microglial activity. Given the advantage of zebrafish larvae for minimally-invasive imaging approaches, we sought for the first time to describe the microglial responses after acute seizures in two different zebrafish larval models: a chemically-induced epileptic model by the systemic injection of kainate at 3 days post-fertilization, and the didys552 genetic epilepsy model, which carries a mutation in scn1lab that leads to spontaneous epileptiform discharges. Kainate-treated larvae exhibited transient brain damage as shown by increased numbers of apoptotic nuclei as early as one day post-injection, which was followed by an increase in the number of microglia in the brain. A similar microglial phenotype was also observed in didys552-/- mutants, suggesting that microglia numbers change in response to seizure-like activity in the brain. Interestingly, kainate-treated larvae also displayed a decreased seizure threshold towards subsequent pentylenetetrazole-induced seizures, as shown by higher locomotor and encephalographic activity in comparison with vehicle-injected larvae. These results are comparable to kainate-induced rodent seizure models and suggest the suitability of these zebrafish seizure models for future studies, in particular to elucidate the links between epileptogenesis and microglial dynamic changes after seizure induction in the developing brain, and to understand how these modulate seizure susceptibility.

Immunological Imbalances Associated with Epileptic Seizures in Type 2 Diabetes Mellitus

PURPOSE OF THE REVIEW

Type 2 diabetes mellitus (T2DM) is a global health burden that leads to an increased morbidity and mortality rate arising from microvascular and macrovascular complications. Epilepsy leads to complications that cause psychological and physical distress to patients and carers. Although these conditions are characterized by inflammation, there seems to be a lack of studies that have evaluated inflammatory markers in the presence of both conditions (T2DM and epilepsy), especially in low-middle-income countries where T2DM is epidemic. Summary findings: In this review, we describe the role of immunity in the seizure generation of T2DM. Current evidence shows an increase in the levels of biomarkers such as interleukin (IL-1β, IL-6, and IL-8), tumour necrosis factor-α (TNF-α), high mobility group box-1 (HMGB1), and toll-like receptors (TLRs) in epileptic seizures and T2DM. However, there is limited evidence to show a correlation between inflammatory markers in the central and peripheral levels of epilepsy.

CONCLUSIONS

Understanding the pathophysiological mechanism behind epileptic seizures in T2DM through an investigation of immunological imbalances might improve diagnosis and further counter the risks of developing complications. This might also assist in delivering safe and effective therapies to T2DM patients affected, thus reducing morbidity and mortality by preventing or reducing associated complications. Moreover, this review also provides an overview approach on inflammatory cytokines that can be targeted when developing alternative therapies, in case these conditions coexist.

New approaches for brain arteriovenous malformations-related epilepsy

BACKGROUND

The purpose of this review is to present the current literature and to highlight the most recent findings in brain arteriovenous malformations (bAVM)-related epilepsy research.

METHODS

We searched Medline, PubMed, Biblioinserm, Cochrane Central to study the latest research reports about the different factors that could be responsible for the genesis of bAVM-related epilepsy. We analyzed if epileptogenesis has any characteristics traits and its relation with the vascular malformation. The results of different treatments on epilepsy were considered. Typical errors that may lead towards incorrect or worse management of the seizures for these patients were also examined.

RESULTS

The development of bAVM results from multifactorial etiologies and bAVM-related epileptogenesis is likely specific for this pathology. Different types of evidence demonstrate a bidirectional relationship between bAVM and epilepsy. Currently, there is not enough published data to determine what may be the right management for these patients.

CONCLUSIONS

A better understanding of epileptogenesis in conjunction with knowledge of the complex alterations of structures and functions following bAVM-related seizures is necessary. Identification of biomarkers that can identify subgroups most likely to benefit from a specific intervention are needed to help guide clinical management. A new concept for the treatment of epilepsy related to an unruptured bAVM that cannot be treated invasively is proposed as well as new therapeutic perspectives. The next necessary step will be to propose additional algorithms to improve the development of future trials.

Design and evaluation of chrysin-loaded nanoemulsion against lithium/pilocarpine-induced status epilepticus in rats; emphasis on formulation, neuronal excitotoxicity, oxidative stress, microglia polarization, and AMPK/SIRT-1/PGC-1α pathway

OBJECTIVES

The present study aims to formulate and evaluate the efficacy of chrysin-loaded nanoemulsion (CH NE) against lithium/pilocarpine-induced epilepsy in rats, as well as, elucidate its effect on main epilepsy pathogenesis cornerstones; neuronal hyperactivity, oxidative stress, and neuroinflammation.

METHODS

NEs were characterized by droplet size, zeta potential, pH, in vitro release, accelerated and long-term stability studies. Anti-convulsant efficacy of the optimized formula and underlying mechanisms involved were assessed and compared to that from CH suspension given orally at a 30 folds higher dose.

RESULTS

Optimized formula displayed a droplet size of 48.09 ± 0.83 nm, PDI 0.25 ± 0.011, sustained release, and good stability. CH treatment reduced seizures scoring, corrected behavioral and histological changes induced by Li/Pilo. Moreover, CH restored neurotransmitters balance and oxidative stress markers levels. Besides, CH induced microglia polarization from M1 to M2 hindering inflammation induced by Li/Pilo. Also, CH restored energy metabolism homeostasis via regulating protein expression of AMPK/SIRT-1/PGC-1α pathway markers. CH NE formulation was found to significantly enhance drug delivery to rats' hippocampus compared to CH suspension.

CONCLUSION

Our findings prove the therapeutic efficacy of CH NE at a lower dose which could be a potential brain targeting platform to combat epilepsy.

Incidence and risk factors of posttraumatic epilepsy following pediatric traumatic brain injury: A systematic review and meta-analysis

Posttraumatic epilepsy (PTE) is a well-known chronic complication following traumatic brain injury (TBI). Despite some evidence that age at the time of injury may influence the likelihood of PTE, the incidence of PTE in pediatric populations remains unclear. We therefore conducted a systematic review to determine the overall reported incidence of PTE, and explore potential risk factors associated with PTE after pediatric TBI. A comprehensive literature search of the PubMed, Embase, and Web of Science databases was conducted, including randomized controlled trials and cohort studies assessing the incidence of PTE in TBI pediatric patients. We excluded studies with a sample size of <10 patients and those in which a pediatric cohort was not clearly discernable. The review was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We found that the overall incidence of PTE following pediatric TBI was 10% (95% confidence interval [CI] = 5.9%-15%). Subgroup analysis of a small number of studies demonstrated that the occurrence of early seizures (cumulative incidence ratio [CIR] = 7.28, 95% CI = 1.09-48.4, p = .040), severe TBI (CIR = 1.81, 95% CI = 1.23-2.67, p < .001), and intracranial hemorrhage (CIR = 1.60, 95% CI = 1.06-2.40, p = .024) increased the risk of PTE in this population. Other factors, including male sex and neurosurgical intervention, were nonsignificantly associated with a higher incidence of PTE. In conclusion, PTE is a significant chronic complication following childhood TBI, similar to in the adult population. Further standardized investigation into clinical risk factors and management guidelines is warranted. PROSPERO ID# CRD42021245802.

Lipopolysaccharide (LPS) increases susceptibility to epilepsy via interleukin-1 type 1 receptor signaling

Epilepsy is the most common disease of the nervous system, characterized by aberrant normal brain activity. Neuroinflammation is a prominent feature in the brain in epileptic humans and animal models of epilepsy. However, it remains elusive as to how peripheral inflammation affects epilepsy. Herein we demonstrated significantly greater seizure susceptibility and severity of epilepsy under kainic acid (KA) via intraperitoneal (i.p.) injection of lipopolysaccharide (LPS) in mouse model of epilepsy. Nissl staining was employed for assessment of the neuronal damage, immunofluorescence for staining of the microglial cells and astrocytes in the mouse brain slices, and ELISA for detection of the changes of inflammatory factors. We observed a smaller population of viable neurons in CA1 and CA3 regions, a greater population of IBA-1-positive and GFAP-positive cells, with a significant upregulation of IL-1β and IL-6 in hippocampus of epileptic mice when treated with LPS, indicating that LPS aggravates hippocampal neuron injury in epilepsy, and induces neuroinflammation in the hippocampus. In addition, we provide an evident increase in BrdU⁺/DCX⁺ and Nestin⁺ cell populations in dentate gyrus (DG) in LPS-treated group, versus saline group on epileptic mouse model, which demonstrated LPS treatment enhanced hippocampal neurogenesis. In order to investigate whether interleukin-1 type 1 (IL-1R1) signaling is involved in this process, we adopted IL-1R1 globally restored mice (IL-1R1^GR/GR) as an IL-1R1 reporter to visualize labeling of IL-1R1 mRNA and protein by means of RFP staining. Strikingly, the RFP immunofluorescence revealed increased IL-1R1 expression in LPS-treated group, versus saline group. Further, blockage of central IL-1R1 alleviated seizure susceptibility and severity of epilepsy. In summary, our findings suggested that LPS could enhance central inflammatory response and aggravate the susceptibility to epileptic seizure, which we postulated to be mediated by IL-1R1.

Relationship between chronic hypoxia and seizure susceptibility

Chronic hypobaric hypoxia in high‐altitude areas is closely related to the occurrence of many neurological diseases. Among these diseases, epilepsy is a common disease of the nervous system that is difficult to diagnose and treat, with a long treatment cycle. As of 2019, there were more than 70 million epilepsy patients worldwide, including 10 million in China. Studies have shown that chronic hypoxia promotes the occurrence and development of epilepsy, and elucidation of the relationship between chronic hypoxia and epilepsy is important for studying the pathogenesis of epilepsy and exploring the potential characteristics of epilepsy and new drug targets for epilepsy. In this article, we review the factors that may cause increased seizure susceptibility in chronic hypoxia and consider the potential relationship between chronic hypobaric hypoxia and seizure susceptibility in high‐altitude areas and prospects surrounding related research in the future.

Inflammation in pediatric epilepsies: Update on clinical features and treatment options

The role of inflammation is increasingly recognized in triggering or sustaining epileptic activity. In the last decades, increasing research has provided definite evidence to support the link between immunity, inflammatory process, and epilepsy. Neuro- and systemic inflammation play a pivotal role in driving epileptogenesis through different pathogenetic mechanisms: the activation of innate immunity in glia, neurons, and microvasculature, the brain mediated by blood-brain barrier (BBB) impairment, and the imbalance of pro- and anti-inflammatory molecules produced by both arms of immunity. More recently, research has focused on the adverse effects of maternal or early-life immune activation and cytokine imbalance on fetal neurodevelopment and postnatal epilepsy. A complex crosstalk between the immune and nervous system, and a crucial interplay of genetic, epigenetic, and environmental factors may influence structures and functions of the developing brain. A better understanding of the inflammatory process in promoting epilepsy implies that targeting specific pathways may be effective in seizure control. Multiple targets have been identified so far, and several antiseizure interventions are obtained by inhibiting inflammatory signaling or protecting/restoring BBB. All this evidence has changed the field of epilepsy research and neuropharmacology. Further developments and new treatments will rapidly emerge to improve seizure management in inflammation-related epilepsies. This article is part of the Special Issue "Severe Infantile Epilepsies".

Pediatric traumatic brain injury and a subsequent transient immune challenge independently influenced chronic outcomes in male mice

Traumatic brain injury (TBI) is a major contributor to death and disability worldwide. Children are at particularly high risk of both sustaining a TBI and experiencing serious long-term consequences, such as cognitive deficits, mental health problems and post-traumatic epilepsy. Severe TBI patients are highly susceptible to nosocomial infections, which are mostly acquired within the first week of hospitalization post-TBI. Yet the potential chronic impact of such acute infections following pediatric TBI remains unclear. In this study, we hypothesized that a peripheral immune challenge, such as lipopolysaccharide (LPS)-mimicking a hospital-acquired infection-would worsen inflammatory, neurobehavioral, and seizure outcomes after experimental pediatric TBI. To test this, three-week old male C57Bl/6J mice received a moderate controlled cortical impact or sham surgery, followed by 1 mg/kg i.p. LPS (or 0.9% saline vehicle) at 4 days TBI. Mice were randomized to four groups; sham-saline, sham-LPS, TBI-saline or TBI-LPS (n = 15/group). Reduced general activity and increased anxiety-like behavior were observed within 24 h in LPS-treated mice, indicating a transient sickness response. LPS-treated mice also exhibited a reduction in body weights, which persisted chronically. From 2 months post-injury, mice underwent a battery of tests for sensorimotor, cognitive, and psychosocial behaviors. TBI resulted in hyperactivity and spatial memory deficits, independent of LPS; whereas LPS resulted in subtle deficits in spatial memory retention. At 5 months post-injury, video-electroencephalographic recordings were obtained to evaluate both spontaneous seizure activity as well as the evoked seizure response to pentylenetetrazol (PTZ). TBI increased susceptibility to PTZ-evoked seizures; whereas LPS appeared to increase the incidence of spontaneous seizures. Post-mortem analyses found that TBI, but not LPS, resulted in robust glial reactivity and loss of cortical volume. A TBI × LPS interaction in hippocampal volume suggested that TBI-LPS mice had a subtle increase in ipsilateral hippocampus tissue loss; however, this was not reflected in neuronal cell counts. Both TBI and LPS independently had modest effects on chronic hippocampal gene expression. Together, contrary to our hypothesis, we observed minimal synergy between TBI and LPS. Instead, pediatric TBI and a subsequent transient immune challenge independently influenced chronic outcomes. These findings have implications for future preclinical modeling as well as acute post-injury patient management.

LncRNA Snhg5 Attenuates Status Epilepticus Induced Inflammation through Regulating NF-κΒ Signaling Pathway

Status epilepticus (SE) induced inflammation plays an important role in the pathogenesis of SE. Long non-coding RNA small nucleolar RNA host gene 5 (lncRNA Snhg5) has been reported in various inflammatory diseases. However, the mechanism of Snhg5 regulated inflammation in SE remains unclear. Therefore, this study aimed to clarify the role and mechanism of Snhg5 in SE-induced inflammation in vitro and vivo. In vitro, lipopolysaccharide (LPS)-induced inflammation in microglia was used to mimic the inflammation after SE. In vivo, SE model was induced by lithium chloride and pilocarpine. The level of Snhg5, p65, p-p65, p-inhibitor of kappaB (IκB)α, IκBα and inflammatory factors (tumor necrosis factor (TNF)-α, interleukin (IL)-1β) were measured via quantitative real-time PCR or Western blot. The Nissl stain and immunohistochemical stain were performed to observe hippocampal damage and microglia proliferation. The results showed Snhg5 was up-regulated in the rat and microglia. Knockdown of Snhg5 inhibited LPS-induced inflammation and relative expression of p-65/p65, p-IκBα/IκBα. Moreover, down-regulation of Snhg5 attenuated SE-induced inflammation and reduced the number of microglia in hippocampus. These findings indicated that Snhg5 modulates the inflammation via nuclear factor-kappaB (NF-κB) signaling pathway in SE rats.

Staving Off the Heat With Microglia

Microglial Displacement of GABAergic Synapses Is a Protective Event During Complex Febrile Seizures

Wan Y, Feng B, You Y, et al. Cell Reports. 2020;33(5):108346. doi:10.1016/j.celrep.2020.108346

Complex febrile seizures (FSs) lead to a high risk of intractable temporal lobe epilepsy during adulthood, yet the pathological process of complex FSs is largely unknown. Here, we demonstrate that activated microglia extensively associated with glutamatergic neuronal soma displace surrounding GABAergic presynapses in complex FSs. Patch clamp electrophysiology establishes that the microglial displacement of GABAergic presynapses abrogates a complex-FS-induced increase in GABAergic neurotransmission and neuronal excitability, whereas GABA exerts an excitatory action in this immature stage. Pharmacological inhibition of microglial displacement of GABAergic presynapses or selective ablation of microglia in CD11b^DTR mice promotes the generation of complex FSs. Blocking or deleting the P2Y₁₂ receptor (P2Y₁₂R) reduces microglial displacement of GABAergic presynapses and shortens the latency of complex FSs. Together, microglial displacement of GABAergic presynapses, regulated by P2Y₁₂R, reduces neuronal excitability to mitigate the generation of complex FSs. Microglial displacement is a protective event during the pathological process of complex FSs.

Exercise-linked consequences on epilepsy

OBJECTIVE

Epilepsy is a brain disorder that leads to seizures and neurobiological, cognitive, psychological, and social consequences. Physical inactivity can contribute to worse epilepsy pathophysiology. Here, we review how physical exercise affects epilepsy physiopathology.

METHODS

An extensive literature search was performed and the mechanisms of physical exercise on epilepsy were discussed. The search was conducted in Scopus and PubMed. Articles with relevant information were included. Only studies written in English were considered.

RESULTS

The regular practice of physical exercise can be beneficial for individuals with neurodegenerative diseases, such as epilepsy by decreasing the production of pro-inflammatory and stress biomarkers, increasing socialization, and reducing the incidence of epileptic seizures. Physical exercise is also capable of reducing the symptoms of depression and anxiety in epilepsy. Physical exercise can also improve cognitive function in epilepsy. The regular practice of physical exercise enhances the levels of brain-derived neuro factor (BDNF) in the hippocampi, induces neurogenesis, inhibits oxidative stress and reactive gliosis, avoids cognitive impairment, and stimulates the production of dopamine in the epileptic brain.

CONCLUSION

Physical exercise is an excellent non-pharmacological tool that can be used in the treatment of epilepsy.

Negative Feedback Role of Astrocytes in Shaping Excitation in Brain Cell Co-cultures

Glial cells play an important role in maintaining neuronal homeostasis and may thus influence excitability in epileptogenesis. These cells in the brain have glutamate (Glu) transporters, which remove this neurotransmitter from the extracellular space. Lack of negative (-) feedback makes local neuronal circuits more excitable and potentially contributing to epileptogenic phenomena. In this study, the role of glial cells in providing (-) feedback is shown through different models of brain cells in culture imaged for intracellular calcium concentration [(Ca²⁺)_i]. Moreover, here we study the individual cells by putting them in categories. Neuronal networks with high and low (-) feedback were established by using anti-mitotics to deplete glial cells. Separate stimuli with very low subthreshold concentrations of Glu (250-750 nM) were added to cultures to test if the order of stimulations matter in regard to calcium dynamics outcomes. Additionally, KCl and ATP were used to stimulate glial cells. We found that for cultures high in (-) feedback, order of the stimulus was not important in predicting cellular responses and because of the complexity of networks in low (-) feedback cultures the order of stimulus matters. As an additional method for analysis, comparison of high (-) feedback cultures, and pure astrocytes was also considered. Glial cells in pure astrocyte cultures tend to be larger in size than glial cells in high (-) feedback cultures. The potential effect of (-) feedback at the blood brain barrier (BBB) was also considered for the inflammatory responses of nitric oxide (NO) production and [Ca²⁺]_i regulation using brain microvascular endothelial cells (BMVECs). The inflammatory and calcium signaling pathways both indicate the negative feedback role of astrocytes, poised between the BBB and structures deeper within the brain, where neuronal synapses are homeostatically maintained by glial uptake of neurotransmitters.

Nano dot blot: An alternative technique for protein identification and quantification in a high throughput format

BACKGROUND

Dot blot technique has been used in a similar way to western blotting, with the major difference being the lack of protein separation with electrophoresis. Protein samples are spotted over a membrane paper, the identification and quantification of a protein is achieved by immunodetection procedures such as colorimetry, fluorescence or chemiluminescence. This technique is widely accepted, but it uses large amounts of sample and antibodies to reveal the presence of the target protein. Significant milestones have been reached to achieve better results with the use of less sample and reagents; however, the ninety-six-well format is still in use.

NEW METHOD

In this work, we propose an innovation to this technique, reducing the amount of sample and antibodies to identify a specific protein when compared to the regular dot blot method. Procedure consists of using a sample volume of approximately 200 nanoliters deposited with a multineedle device developed by our group.

RESULTS

Five samples of standard protein or antigen can be spotted in a Cartesian format to identify and quantify the protein involved in physiological or pathological conditions. In addition, at least five replicates of sample or antigen are used to enable better statistics to calculate the concentration of every standard and the protein present in a sample.

CONCLUSIONS

Hundreds of samples can be deposited in a few minutes and analyzed in a single experimental session. To validate this method, which we called nano dot blot, six proteins involved in the inflammation process were tested in acute and chronic rat models of seizures.

Increased Excitatory Synaptic Transmission Associated with Adult Seizure Vulnerability Induced by Early-Life Inflammation in Mice

Early-life inflammatory stress increases seizure susceptibility later in life. However, possible sex- and age-specific differences and the associated mechanisms are largely unknown. C57BL/6 mice were bred in house, and female and male pups were injected with lipopolysaccharide (LPS; 100 μg/kg, i.p.) or vehicle control (saline solution) at postnatal day 14 (P14). Seizure threshold was assessed in response to pentylenetetrazol (1% solution, i.v.) in adolescence (∼P40) and adulthood (∼P60). We found that adult, but not adolescent, mice treated with LPS displayed ∼34% lower seizure threshold compared with controls. Females and males showed similar increased seizure susceptibility, suggesting that altered brain excitability was age dependent, but not sex dependent. Whole-cell recordings revealed no differences in excitatory synaptic activity onto CA1 pyramidal neurons from control or neonatally inflamed adolescent mice of either sex. However, adult mice of both sexes previously exposed to LPS displayed spontaneous EPSC frequency approximately twice that of controls, but amplitude was unchanged. Although these changes were not associated with alterations in dendritic spines or in the NMDA/AMPA receptor ratio, they were linked to an increased glutamate release probability from Schaffer collateral, but not temporoammonic pathway. This glutamate increase was associated with reduced activity of presynaptic GABA_B receptors and was independent of the endocannabinoid-mediated suppression of excitation. Our new findings demonstrate that early-life inflammation leads to long-term increased hippocampal excitability in adult female and male mice associated with changes in glutamatergic synaptic transmission. These alterations may contribute to enhanced vulnerability of the brain to subsequent pathologic challenges such as epileptic seizures.SIGNIFICANCE STATEMENT Adult physiology has been shown to be affected by early-life inflammation. Our data reveal that early-life inflammation increases excitatory synaptic transmission onto hippocampal CA1 pyramidal neurons in an age-dependent manner through disrupted presynaptic GABA_B receptor activity on Schaffer collaterals. This hyperexcitability was seen only in adult, and not in adolescent, animals of either sex. The data suggest a maturation process, independent of sex, in the priming action of early-life inflammation and highlight the importance of studying mature brains to reveal cellular changes associated with early-life interventions.

Interleukin-22 Plays a Protective Role by Regulating the JAK2-STAT3 Pathway to Improve Inflammation, Oxidative Stress, and Neuronal Apoptosis following Cerebral Ischemia-Reperfusion Injury

The interleukins (ILs) are a pluripotent cytokine family that have been reported to regulate ischemic stroke and cerebral ischemia/reperfusion (I/R) injury. IL-22 is a member of the IL-10 superfamily and plays important roles in tissue injury and repair. However, the effects of IL-22 on ischemic stroke and cerebral I/R injury remain unclear. In the current study, we provided direct evidence that IL-22 treatment decreased infarct size, neurological deficits, and brain water content in mice subjected to cerebral I/R injury. IL-22 treatment remarkably reduced the expression of inflammatory cytokines, including IL-1β, monocyte chemotactic protein- (MCP-) 1, and tumor necrosis factor- (TNF-) α, both in serum and the ischemic cerebral cortex. In addition, IL-22 treatment also decreased oxidative stress and neuronal apoptosis in mice after cerebral I/R injury. Moreover, IL-22 treatment significantly increased Janus tyrosine kinase (JAK) 2 and signal transducer and activator of transcription (STAT) 3 phosphorylation levels in mice and PC12 cells, and STAT3 knockdown abolished the IL-22-mediated neuroprotective function. These findings suggest that IL-22 might be exploited as a potential therapeutic agent for ischemic stroke and cerebral I/R injury.

Cannabinoids: A New Perspective on Epileptogenesis and Seizure Treatment in Early Life in Basic and Clinical Studies

Neural hyperexcitability in the event of damage during early life, such as hyperthermia, hypoxia, traumatic brain injury, status epilepticus, or a pre-existing neuroinflammatory condition, can promote the process of epileptogenesis, which is defined as the sequence of events that converts a normal circuit into a hyperexcitable circuit and represents the time that occurs between the damaging event and the development of spontaneous seizure activity or the establishment of epilepsy. Epilepsy is the most common neurological disease in the world, characterized by the presence of seizures recurring without apparent provocation. Cannabidiol (CBD), a phytocannabinoid derived from the subspecies Cannabis sativa (CS), is the most studied active ingredient and is currently studied as a therapeutic strategy: it is an anticonvulsant mainly used in children with catastrophic epileptic syndromes and has also been reported to have anti-inflammatory and antioxidant effects, supporting it as a therapeutic strategy with neuroprotective potential. However, the mechanisms by which CBD exerts these effects are not entirely known, and the few studies on acute and chronic models in immature animals have provided contradictory results. Thus, it is difficult to evaluate the therapeutic profile of CBD, as well as the involvement of the endocannabinoid system in epileptogenesis in the immature brain. Therefore, this review focuses on the collection of scientific data in animal models, as well as information from clinical studies on the effects of cannabinoids on epileptogenesis and their anticonvulsant and adverse effects in early life.

A Review of Febrile Seizures: Recent Advances in Understanding of Febrile Seizure Pathophysiology and Commonly Implicated Viral Triggers

Febrile seizures are one of the commonest presentations in young children, with a 2-5% incidence in Western countries. Though they are generally benign, with rare long-term sequelae, there is much to be learned about their pathophysiology and risk factors. Febrile seizures are propagated by a variety of genetic and environmental factors, including viruses and vaccines. These factors must be taken into consideration by a clinician aiming to assess, diagnose and treat a child presenting with fevers and seizures, as well as to explain the sequelae of the febrile seizures to the concerned parents of the child. Our article provides an overview of this common childhood condition, outlining both the underlying mechanisms and the appropriate clinical approach to a child presenting with febrile seizures.