Pathogenesis Of Seizures Research Articles

Role of inflammasomes and neuroinflammation in epilepsy.

Epilepsy is a brain disorder characterized by recurrent seizures, which are brief episodes of abnormal electrical activity in the brain and involuntary movement that can lead to physical injury and loss of consciousness. Seizures are canonically accompanied by increased inflammatory cytokine production that promotes neuroinflammation, brain pathology, and seizure propagation. Understanding the source of pro-inflammatory cytokines which promote seizure pathogenesis could be a gateway to precision epilepsy drug design. This review discusses the inflammasome in epilepsy including its role in seizure propagation and negative impacts on brain health. The inflammasome is a multiprotein complex that coordinates IL-1β and IL-18 production in response to tissue damage, cellular stress, and infection. Clinical evidence for inflammasome signaling in epileptogenesis is reviewed followed by a discussion of emerging strategies to modulate inflammasome activity in epilepsy.

Mechanism of Marinobufagenin-Induced Hyperpermeability of Human Brain Microvascular Endothelial Cell Monolayer: A Potential Pathogenesis of Seizure in Preeclampsia.

Preeclampsia (preE) is a hypertensive disorder in pregnancies. It is the third leading cause of mortality among pregnant women and fetuses worldwide, and there is much we have yet to learn about its pathophysiology. One complication includes cerebral edema, which causes a breach of the blood-brain barrier (BBB). Urinary marinobufagenin (MBG) is elevated in a preE rat model prior to developing hypertension and proteinuria. We investigated what effect MBG has on the endothelial cell permeability of the BBB. Human brain microvascular endothelial cells (HBMECs) were utilized to examine the permeability caused by MBG. The phosphorylation of ERK1/2, Jnk, p38, and Src was evaluated after the treatment with MBG. Apoptosis was evaluated by examining caspase 3/7. MBG ≥ 1 nM inhibited the proliferation of HBMECs by 46-50%. MBG induced monolayer permeability, causing a decrease in the phosphorylation of ERK1/2 and the activated phosphorylation of Jnk, p38, and Src. MBG increased the caspase 3/7 expression, indicating the activation of apoptosis. Apoptotic signaling or the disruption of endothelia tight junction proteins was not observed when using the p38 inhibitor as a pretreatment in MBG-treated cells. The MBG-induced enhancement of the HBMEC monolayer permeability occurs by the downregulation of ERK1/2, the activation of Jnk, p38, Src, and apoptosis, resulting in the cleavage of tight junction proteins, and are attenuated by p38 inhibition.

Disorders in Amino Acid Metabolism Associated with Seizures

Seizures are a common presenting manifestation in children with amino acid metabolism disorders such as maple syrup urine disease (MSUD), nonketotic hyperglycinemia, sulfite oxidase deficiency, serine deficiency, and GABA-related disorders. In monoamine biosynthesis disorders, seizures are rare, but paroxysmal dystonia is often misdiagnosed as seizures. Metabolic changes, including amino acid turnover, have been noted during epileptogenesis and chronic epilepsy. Autophagy, a catabolic pathway crucial for maintaining tissue and organism homeostasis, is influenced by amino acids and plays a role in brain physiology and pathology, including epileptic disorders. Amino acid synthesis defects can cause neurological symptoms such as early-onset seizures, mental disability, and skin disorders. Besides neurological symptoms, amino acid metabolism disorders can impact other organ systems, resulting in various clinical manifestations. Early recognition and proper management of these disorders are vital for preventing long-term complications and enhancing patient outcomes. Ongoing research into the complex relationship between amino acid metabolism and neurological function may offer new insights into the pathogenesis of seizures and other neurological disorders.

Potential Mechanisms Involved in the Anticonvulsant Effect of Recombinant Human VEGF on Maximal Electroshock-induced Seizure

Background: Vascular endothelial growth factor (VEGF) signaling pathway plays an important role in the pathogenesis of seizure. The oxidant/antioxidant factors and miRNA expression in the brain are differentially regulated in seizure. Objectives: We aim to investigate the potential mechanism of action for the recombinant human VEGF (rhVEGF) in mice with maximal electroshock (MES)-induced seizure. Materials & Methods: A total of 40 male mice (weight: 20-25 g) were treated intraperitoneally with normal saline, or rhVEGF (50, 100, and 150 µg/kg, daily for 4 consecutive days). One hour after the last injection, seizures were induced in each animal by MES. The latency for the onset of the first clonus and the duration of hind limb extension (HLE) were recorded. The levels of nitric oxide (NO), total antioxidant capacity (TAC), and micoRNA-142-5p expression were determined in the hippocampus of mice. Blood-brain barrier (BBB) permeability was also estimated by Evans blue dye extravasation method. Results: The administration of rhVEGF at all doses significantly reduced the HLE duration. However, latency for the seizure onset increased after administration of 50 and 150 μg/kg rhVEGF and decreased after administration of 100 μg/kg rhVEGF. In the brain, the NO level decreased, while TAC level and microRNA-142-5p expression increased by rhVEGF treatment in mice with MES-induced seizure. Pretreatment with rhVEGF at doses of 100 and 150 μg/kg reversed the increase in BBB leakage induced by MES-induced seizures. Conclusion: The rhVEGF administration can prevent MES-induced seizures by regulating NO, TAC, and miR-142-5 expression levels in the hippocampus and reducing BBB leakage in mice.

Diffusion tensor-based analysis of white matter in dogs with idiopathic epilepsy.

The understanding of epileptic seizure pathogenesis has evolved over time, and it is now generally accepted that not only are cortical and subcortical areas involved but also the connection of these regions in the white matter (WM). Recent human neuroimaging studies confirmed the involvement of the WM in several epilepsy syndromes. Neuroimaging studies investigating WM integrity with diffusion tensor imaging (DTI) in canine idiopathic epilepsy are lacking. This study aimed to test the hypothesis that WM diffusion changes can be found in dogs affected by idiopathic epilepsy. Twenty-six dogs with idiopathic epilepsy (15 Border Collies and 11 Greater Swiss Mountain dogs) and 24 healthy controls (11 Beagle dogs, 5 Border Collies, and 8 Greater Swiss Mountain dogs) were prospectively enrolled. Most dogs with idiopathic epilepsy (17/26) were enrolled within 3 months after seizure onset. Diffusion tensor imaging of the brain with 32 diffusion directions (low b value = 0 s/mm2; maximal b value = 800 s/mm2) was performed in a 3 Tesla scanner. Tract-based spatial statistics (TBSS), a voxel-based approach, was used to investigate changes in fractional anisotropy (FA) and mean diffusivity (MD) in the idiopathic epilepsy group compared to the healthy control group. Additionally, FA and MD were investigated in the region of corpus callosum and cingulate white matter in both groups. We observed subtle changes in WM DTI between the idiopathic epilepsy group and the healthy control group limited to cingulate WM, with a significantly lower FA in the idiopathic epilepsy group compared to the healthy control group in the region of interest (ROI) approach (p = 0.027). No significant changes were found between the idiopathic epilepsy group and the healthy control group in the TBSS analysis and in the corpus callosum in the ROI approach. This study supports the cingulate area as a target structure in canine epilepsy. The subtle changes only might be explained by the short duration of epilepsy, small sample sizes, and the higher variability in canine brain anatomy. Furthermore, all included dogs showed generalized tonic-clonic seizures, possibly affected by generalized epilepsy syndrome, which are also associated with less pronounced DTI changes in humans than focal epilepsy syndromes.

Decrease of Cellular Communication Network Factor 1 (CCN1) Attenuates PTZ-Kindled Epilepsy in Mice.

To investigate the molecular mechanism of communication network factor 1 (CCN1) regulating pentylenetetrazol (PTZ)-induced epileptogenesis, deepen the understanding of epilepsy seizure pathogenesis, and provide new drug action targets for its clinical prevention and treatment. Differentially expressed genes (DEGs) on microarrays GSE47516 and GSE88992 were analyzed online using GEO2R. Pathway enrichment and protein-protein interaction network (PPI) analysis of DEGs were carried out using Metascape. Brain tissue samples of severe traumatic brain injury patients (named Healthy group) and refractory epilepsy patients (named Epilepsy group) were obtained and analyzed by qRT-PCR and immunohistochemistry (IHC) staining. A PTZ-induced epilepsy mouse model was established and verified. Morphological changes of neurons in mouse brain tissue were detected using hematoxylin and eosin (HE) staining. qRT-PCR was conducted to detect the mRNA expressions of apoptosis-associated proteins Bax, Caspase-3 and bcl2. TUNEL staining was performed to detect brain neuron apoptosis. The levels of myocardial enzymology, GSH, MDA and ROS in blood of mouse were detected by biochemical assay. CCN1 expression was increased in epilepsy brain tissue samples. CCN1 decreasing effectively prolongs seizure incubation period and decreases seizure duration. Silencing of CCN1 also reduces neuronal damage and apoptosis, decreases mRNA and protein expression of proapoptotic proteins Bax and Caspase-3, increases mRNA expression of antiapoptotic protein Bcl2. Moreover, decrease of CCN1 decreases myocardial enzymatic indexes CK and CK-MB levels, reduces myocardial tissue hemorrhage, and relieves oxidative stress response in hippocampal and myocardial tissue. CCN1 expression is increased in epileptic samples. CCN1 decreasing protects brain tissue by attenuating oxidative stress and inhibiting neuronal apoptosis triggered by PTZ injection, which probably by regulating Nrf2/HO-1 pathway.

The role of neuroinflammation in canine epilepsy

The lack of therapeutics that prevent the development of epilepsy, improve disease prognosis or overcome drug resistance represents an unmet clinical need in veterinary as well as in human medicine. Over the past decade, experimental studies and studies in human epilepsy patients have demonstrated that neuroinflammatory processes are involved in epilepsy development and play a key role in neuronal hyperexcitability that underlies seizure generation. Targeting neuroinflammatory signaling pathways may provide a basis for clinically relevant disease-modification strategies in general, and moreover, could open up new therapeutic avenues for human and veterinary patients with drug-resistant epilepsy. A sound understanding of the neuroinflammatory mechanisms underlying seizure pathogenesis in canine patients is therefore essential for mechanism-based discovery of selective epilepsy therapies that may enable the development of new disease-modifying treatments. In particular, subgroups of canine patients in urgent needs, e.g. dogs with drug-resistant epilepsy, might benefit from more intensive research in this area. Moreover, canine epilepsy shares remarkable similarities in etiology, disease manifestation, and disease progression with human epilepsy. Thus, canine epilepsy is discussed as a translational model for the human disease and epileptic dogs could provide a complementary species for the evaluation of antiepileptic and antiseizure drugs. This review reports key preclinical and clinical findings from experimental research and human medicine supporting the role of neuroinflammation in the pathogenesis of epilepsy. Moreover, the article provides an overview of the current state of knowledge regarding neuroinflammatory processes in canine epilepsy emphasizing the urgent need for further research in this specific field. It also highlights possible functional impact, translational potential and future perspectives of targeting specific inflammatory pathways as disease-modifying and multi-target treatment options for canine epilepsy.

The recycling of AMPA receptors/GABAa receptors is related to neuronal excitation/inhibition imbalance and may be regulated by KIF5A.

Excitation/inhibition imbalance (E/I imbalance), which involves an increase of alpha-amino-3-hydroxy-5-methyl-4-isoxazole (AMPA) receptors (AMPARs) and decrease of gamma-aminobutyric acid type A (GABA) type A receptors (GABAaRs) on the neuron surface, has been documented in the pathogenesis of seizures. Notably, it has been established that both the glutamate receptor subunit 2 (GluR2) of AMPARs and beta 2/3 subunits of GABAaRs (Gabrb2+3) participate in the recycling mechanism mediated by the kinesin heavy chain isoform 5A (KIF5A), which determines the number of neuron surface receptors. However, it remains unclear whether receptor recycling is involved in the pathogenesis of seizures. Twelve adult male Sprague-Dawley rats were randomly allocated to the normal control (Ctl) group (n=6) and the pentylenetetrazol (PTZ)-induced seizure (Sez) group (n=6). The rats in the Ctl group were treated with saline. The rats in the Sez group received an intraperitoneal injection of PTZ at an initial dose of 40 mg/kg. Primary cultured neurons were obtained from newborn rats (24-hour-old). The neurons were exposed to magnesium-free (Mg2+-free) extracellular fluid for 3 hours to establish the seizure model in vitro. We detected the electrophysiology of the seizure model, the expression levels of KIF5A, GluR2, and Gabrb2+3, the recycling ratio of GluR2 and Gabrb2+3, the interaction between KIF5A and GluR2, and the interaction between KIF5A and Gabrb2+3. In the Sez group, the expression of GluR2 on the cell surface was increased and the expression of Gabrb2+3 on the cell surface was decreased. The amplitude and frequency of action potentials were significantly increased in the Mg2+-free group. The amplitude and decay time of AMPAR-mediated miniature excitatory postsynaptic currents were increased in the Mg2+-free group. The amplitude and decay time of miniature inhibitory postsynaptic currents were decreased in the Mg2+-free group. The recycling ratio of GluR2 was increased and the recycling ratio of Gabrb2+3 was decreased in the Mg2+-free group. The interaction between KIF5A and GluR2 was increased, and the interaction between KIF5A and Gabrb2+3 was decreased in the seizure model in vivo and in vitro. The recycling of AMPA receptors/GABAa receptors is related to E/I imbalance and may be regulated by KIF5A.

Post COVID-19 Multisystemic Inflammatory Syndrome Revealed by Seizures: A Case Report

The Covid-19 infection disrupts various organs, including the liver, kidney, and nervous system. Common neurological symptoms of the Covid-19 infection include delirium, confusion, headache, and loss of sense of smell and taste. In rare cases it can cause seizure. The virus enters the nervous system either directly through nerve pathways or indirectly through the ACE2 receptor. Understanding the potential mechanisms is necessary to gain better insight into COVID-19 induced seizure pathogenesis and to design the correct treatment strategies to achieve appropriate treatment for seizure and epilepsy. We report the case of a child with post covid syndrome with multisystemic inflammatory syndrome damage, and we explain the mechanisms of the damage to the nervous system.

Epilepsy in the 21st century

Epilepsy research has progressed substantially over the past 20 years. In this Round-up that celebrates the 20th Anniversary of the journal, I outline the advances that I consider to be most notable, including those in the taxonomy and pathogenesis of seizures and epilepsies, as well as in understanding seizure onset and propagation, genetics, and acquired causes of epilepsy. I also discuss the improvements in seizure detection, medical treatment, brain imaging, and outcomes of epilepsy surgery.

Periventricular hypodensity is associated with the incidence of pre-shunt seizure in hydrocephalic children.

The seizure incidence in hydrocephalic children has been acknowledged in a lot of studies previously; nonetheless, seizure pathogenesis in these children remains unclear. Its high proportion of hydrocephalic children who underwent shunt surgery suggests that the seizure might be associated with the protocol of shunt placement and/or the shunt existence intracranially; however, this hypothesis could not explain the pre-shunt seizure incidence in hydrocephalic children. This study aims to evaluate the patients' characteristics and CT findings in pre-shunt hydrocephalic children to identify the possible seizure etiology in these patients. Three hundred and thirty-four children with hydrocephalus were included in this study, including 147 hydrocephalic children with the pre-shunt seizure history and 187 hydrocephalic children presented without the pre-shunt seizure history. The following information was retrieved from the patients' medical records: gender, age, pediatric Glasgow Coma Scale (pGCS) upon admission, and hydrocephalus diagnoses. CT findings were re-evaluated to assess the compression association of sulci and gyri, Sylvian fissures, cisterns, FH/ID ratio, Evan's ratio, and periventricular hypodensity with pre-shunt seizure. The results show that the pre-shunt seizure incidence is significantly higher in hydrocephalic children aged 1 to 5years old (63/113 (55%), p = 0.0001), diagnosed with communicating hydrocephalus (97/163 (59%), p = 0.0001) or infectious hydrocephalus (80/109 (73%), p = 0.0001). The presence of periventricular hypodensity is significantly associated with the pre-shunt seizure incidence (132/205 (64.3%), p = 0.0001). Results from univariate analyses suggest significant association between periventricular hypodensity in every location and pre-shunt seizure (p < 0.0001). Multivariate analyses identify that temporal horn in the right lateral ventricle as the location of periventricular hypodensity has the strongest association with the pre-shunt seizure. The presence of periventricular hypodensity in head CT scan is significantly associated with the pre-shunt seizure incidence. Further investigation to confirm this finding and evaluate the possible roles of inflammation in the pre-shunt seizure in hydrocephalic children is important to seek its possible implication on the treatment of pre-shunt seizure in these children.

Role of the &lt;i&gt;GRIN1&lt;/i&gt; gene polymorphism in the formation of post-traumatic epilepsy

Introduction: NMDA receptors are involved in the pathogenesis of seizures, as it subunit is coded for by the GRIN1 gene. Different GRIN1 mutations are known in patients with different forms of epilepsy and encephalopathy. However, no data are available on the participation of the GRIN1 gene and its polymorphisms in the development of post-traumatic epilepsy (PTE). Aim: To determine the influence of single-nucleotide rs1126442 polymorphism of GRIN1 on the risk of PTE formation. Materials and methods: A total of 140 patients were examined, which included 69 patients with PTE and 71 patients with genetic epilepsy. All patients underwent a comprehensive examination, with evaluation of history, neurological status, electroencephalography (EEG) and neuroimaging results, and genotyping of blood samples by real-time polymerase chain reaction. The control sample for genetic examination was venous blood from 60 healthy individuals. Results: Focal seizures with transition to bilateral and tonicclonic seizures were predominant in the PTE group. Neuroimaging revealed dystrophic, cystic, and cystogliotic alterations and signs of external hydrocephaly. EEG recorded interictal and ictal epileptiform activity and slowing of theta waves. Genotyping by rs1126442 polymorphism of GRIN1 revealed predominance of heterozygous G/A and homozygous A/A genotypes in patients with PTE in the codominant (odds ratio (OD)=3.43; 95% confidence index (CI) 1.567.55; p=0.0047), dominant (OR=3.24; 95% CI 1.576.68; p=0.0011), and superdominant (OR=2.90; 95% CI 1.366.22; p=0.0048) inheritance models. The carriage of heterozygous G/A rs1126442 genotype of GRIN1 was associated with an epileptiform activity in the EEG of all patients with epilepsy (OR=2.40; 95% CI 1.115.20; p=0.024). Conclusion: The carriage of heterozygous G/A genotype and homozygous A/A rs 1126442 genotype of GRIN1 in the dominant and codominant inheritance models is associated with a high risk of development of epilepsy after craniocerebral trauma. The carriage of heterozygous G/A rs 1126442 genotype of GRIN1 is associated with an epileptiform activity in EEG.

Lamotrigine effects on immune gene expression in larval zebrafish

PurposeDespite growing evidence that neuroinflammation and pro-inflammatory cytokines are involved in the pathogenesis of seizures and epilepsy, this knowledge has not been incorporated in the proposed mechanism of action of any of the current antiseizure medications (ASMs). Here, we tested the hypothesis by assessing inflammation markers in larval zebrafish (Danio rerio) exposed to lamotrigine (LTG). MethodsIn order to establish the most appropriate LTG concentrations for the transcriptome analysis (RNAseq), we initially assessed for teratogenic (spinal cord deformation, heart oedema, failed inflation of the swim bladder) and behavioural effects (distance moved, time spent active, and average swimming speed during a light/dark test) in zebrafish larvae exposed to 0, 50, 100, 300, 500, 750, and 1000 μM LTG continuously between 5 and 120 h post fertilisation. Subsequently, we repeated the experiment with 0, 50, 100, or 300 μM LTG for transcriptomic analyses. Two databases (Kyoto Encyclopedia of Genes and Genomes; Gene Ontology) were used to interpret changes in gene expression between groups. ResultsMajor teratogenic effects were observed at concentrations of ≥ 500 μM LTG, whereas behavioural changes were observed at ≥ 300 μM LTG. Transcriptome analysis revealed a non-linear response to LTG. From the suite of differentially expressed genes (DEG), 85% (n = 80 DEGs) were upregulated following exposure to 50 μM LTG, whereas 58% (n = 12 DEGs) and 91% (n = 210 DEGs) were downregulated in response to 100 and 300 μM LTG. The metabolic pathways affected following exposure to 50 and 300 μM LTG were associated with responses to inflammation and pathogens as well development and regulation of the immune system in both groups. Notable genes within the lists of DEGs included component complement 3 (C3.a), which was significantly upregulated in response to 50 μM LTG, whereas interleukin 1β (IL-1β) was significantly downregulated in the 300 μM LTG group. The lowest exposure of 50 μM LTG is regarded as clinically relevant to therapeutic exposure. ConclusionWe demonstrated that LTG had an impact on the immune system, with a non-monotonic response curve. This dose-dependent relation could indicate that LTG can affect inflammatory responses and also at clinically relevant concentration. Further studies are needed to establish this method as a tool for screening the effects of ASMs on the immune system.

Improving Effect of Ethyl Acetate Fraction of Tanacetum Parthenium Against Brain Oxidative Damage in Pentylenetetrazole-Induced Seizure Model in Mice

Aims Oxidative stress plays an essential role in the pathogenesis of seizures. In this study, we investigated the effect of ethyl acetate fraction of Tanacetum parthenium against oxidative brain damage in a pentylenetetrazole(PTZ)-induced seizure model in mice. Methods &amp; Materials In this experimental study, mice were divided into 6 groups: control, PTZ, and 4 other groups that, besides PTZ, received 25, 50, 100, and 200 mg/kg of the fraction. PTZ (100 mg/kg) and a fraction (30 min before PTZ) were administered intraperitoneally for 3 weeks. Delay in the onset of the minimal clonic seizure (MCS), generalized tonic-clonic seizure (GTCS), and the level of oxidative stress indexes in cortical and hippocampal tissues were measured. Findings Pretreatment with fraction resulted in postponing the onset seizures in the Fraction+PTZ groups compared to the PTZ group (P&lt;0.05, P&lt;0.01, and P&lt;0.001). In addition, all doses of ethyl acetate fraction decreased the concentration of malondialdehyde (MDA) and increased the level of tom thiol groups and the activity of superoxide dismutase and catalase enzymes in the brain tissues compared to the PTZ group. Conclusion Ethyl acetate fraction of Tanacetum parthenium attenuated PTZ-stimulated seizures through improving brain tissue oxidative stress.

Peripheral blood mononuclear cell activation sustains seizure activity.

The influx of immune cells and serum proteins from the periphery into the brain due to a dysfunctional blood-brain barrier (BBB) has been proposed to contribute to the pathogenesis of seizures in various forms of epilepsy and encephalitis. We evaluated the pathophysiological impact of activated peripheral blood mononuclear cells (PBMCs) and serum albumin on neuronal excitability in an in vitro brain preparation. A condition of mild endothelial activation induced by arterial perfusion of lipopolysaccharide (LPS) was induced in the whole brain preparation of guinea pigs maintained in vitro by arterial perfusion. We analyzed the effects of co-perfusion of human recombinant serum albumin with human PBMCs activated with concanavalin A on neuronal excitability, BBB permeability (measured by FITC-albumin extravasation), and microglial activation. Bioplex analysis in supernatants of concanavalin A-stimulated PBMCs revealed increased levels of several inflammatory mediators, in particular interleukin (IL)-1β, tumor necrosis factor (TNF)-α, interferon (INF)-γ, IL-6, IL-10, IL-17A, and MIP3α. LPS and human albumin arterially co-perfused with either concanavalin A-activated PBMCs or the cytokine-enriched supernatant of activated PBMCs (1) modulated calcium-calmodulin-dependent protein kinase II at excitatory synapses, (2) enhanced BBB permeability, (3) induced microglial activation, and (4) promoted seizure-like events. Separate perfusions of either nonactivated PBMCs or concanavalin A-activated PBMCs without LPS/human albumin (hALB) failed to induce inflammatory and excitability changes. Activated peripheral immune cells, such as PBMCs, and the extravasation of serum proteins in a condition of BBB impairment contribute to seizure generation.

Altered Neurotransmitter Expression in the Corticothalamocortical Network of an Absence Epilepsy Model with impaired Feedforward Inhibition

The episodes of brief unconsciousness in patients with childhood absence epilepsy are a result of corticothalamocortical circuitry dysfunction. This dysfunction may arise from multifactorial mechanisms in patients from different genetic backgrounds. In previous studies using the epileptic stargazer mutant mouse, which experience frequent absence seizures, we reported a deficit in AMPAR-mediated feed-forward inhibition of parvalbumin-containing (PV+) interneurons. Currently, in order to determine the downstream effects of this impairment on neurotransmitter expression, we performed HPLC of tissue lysates and post-embedding electron microscopy from the cortical and thalamic regions. We report region-specific alterations in GABA expression, but not of glutamate, and most prominently at PV+ synaptic terminals. These results suggest that impaired feed forward inhibition may occur via reduced activation of these interneurons and concomitant decreased GABAergic signaling. Further investigations into GABAergic control of corticothalamocortical network activity could be key in our understanding of absence seizure pathogenesis.

Links between Immune Cells from the Periphery and the Brain in the Pathogenesis of Epilepsy: A Narrative Review.

Accumulating evidence has demonstrated that the pathogenesis of epilepsy is linked to neuroinflammation and cerebrovascular dysfunction. Peripheral immune cell invasion into the brain, along with these responses, is implicitly involved in epilepsy. This review explored the current literature on the association between the peripheral and central nervous systems in the pathogenesis of epilepsy, and highlights novel research directions for therapeutic interventions targeting these reactions. Previous experimental and human studies have demonstrated the activation of the innate and adaptive immune responses in the brain. The time required for monocytes (responsible for innate immunity) and T cells (involved in acquired immunity) to invade the central nervous system after a seizure varies. Moreover, the time between the leakage associated with blood–brain barrier (BBB) failure and the infiltration of these cells varies. This suggests that cell infiltration is not merely a secondary disruptive event associated with BBB failure, but also a non-disruptive event facilitated by various mediators produced by the neurovascular unit consisting of neurons, perivascular astrocytes, microglia, pericytes, and endothelial cells. Moreover, genetic manipulation has enabled the differentiation between peripheral monocytes and resident microglia, which was previously considered difficult. Thus, the evidence suggests that peripheral monocytes may contribute to the pathogenesis of seizures.

Seizures and memory impairment induced by patient-derived anti-N-methyl-D-aspartate receptor antibodies in mice are attenuated by anakinra, an interleukin-1 receptor antagonist.

Neuroinflammation associated with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis may facilitate seizures. We previously showed that intraventricular administration of cerebrospinal fluid from patients with anti-NMDAR encephalitis to mice precipitates seizures, thereby confirming that antibodies are directly pathogenic. To determine whether interleukin (IL)-1-mediated inflammation exacerbates autoimmune seizures, we asked whether blocking the effects of IL-1 by anakinra, a selective IL-1 receptor antagonist, blunts antibody-induced seizures. We infused C57BL/6 mice intraventricularly with purified serum IgG from patients with anti-NMDAR encephalitis or monoclonal anti-NMDAR IgG; subdural electroencephalogram was continuously recorded. After a 6-day interval, mice received anakinra (25mg/kg sc, twice daily) or vehicle for 5 days. Following a 4-day washout period, we performed behavioral tests to assess motor function, anxiety, and memory, followed by hippocampus tissue analysis to assess astrocytic (glial fibrillary acidic protein [GFAP]) and microglial (ionized calcium-binding adapter molecule [Iba]-1) activation. Of 31 mice infused with purified patient NMDAR-IgG (n=17) or monoclonal NMDAR-IgG (n=14), 81% developed seizures. Median baseline daily seizure count during exposure to antibodies was 3.9; most seizures were electrographic. Median duration of seizures during the baseline was 82.5s. Anakinra administration attenuated daily seizure frequency by 60% (p=.02). Anakinra reduced seizure duration; however, the effect was delayed and became apparent only after the cessation of treatment (p=.04). Anakinra improved novel object recognition in mice with antibody-induced seizures (p=.03) but did not alter other behaviors. Anakinra reduced the expression of GFAP and Iba-1 in the hippocampus of mice with seizures, indicating decreased astrocytic and microglial activation. Our evidence supports a role for IL-1 in the pathogenesis of seizures in anti-NMDAR encephalitis. These data are consistent with therapeutic effects of anakinra in other severe autoimmune and inflammatory seizure syndromes. Targeting inflammation via blocking IL-1 receptor-mediated signaling may be promising for developing novel treatments for refractory autoimmune seizures.

Angiocentric glioma-associated seizures: The possible role of EATT2, pyruvate carboxylase and glutamine synthetase

PurposeOur purpose was to better understand the pathogenesis of seizures associated with angiocentric glioma. Angiocentric glioma is an indolent and rare low-grade glioma. Its typical clinical presentation is with epileptic seizures. The pathogenesis of tumor-associated seizures is poorly understood. Among the possible pathomechanisms, the increased neurotoxic concentrations of the glutamate has been proposed. Glutamate transporters, pyruvate carboxylase and glutamine synthetase are involved in maintaining the physiological concentration of glutamate in the inter synaptic spaces. MethodsWe evaluated the immunohistochemical expression of EAAT2 (the most important glutamate transporter), pyruvate carboxylase and glutamine synthetase in 17 angiocentric gliomas. ResultsEAAT2 was never expressed (0%) in the neoplastic cells in none of the cases studied. Pyruvate carboxylase was expressed in the cytoplasm of the neoplastic cells in 16/17 cases (94 %). Glutamine synthetase was expressed in the cytoplasm of the neoplastic cells in 15/17 cases (88 %). ConclusionThe net result of this enzymatic expression, in particular considering the loss of EAAT2, could be an increased glutamate concentration in the synaptic clef, which might increase local network excitability initially involving intratumoral neurons. The observation that the angiocentric glioma-associated epilepsy might be at least in part related to EAAT2 deficiency opens up interesting therapeutic perspectives.

Neuroimmune interaction in seizures and epilepsy: focusing on monocyte infiltration.

Epilepsy is a major neurological condition that affects millions of people globally. While a number of interventions have been developed to mitigate this condition, a significant number of patients are refractory to these treatments. Consequently, other avenues of research are needed. One such avenue is modulation of the immune system response to this condition, which has mostly focused on microglia, the resident immune cells of the central nervous system (CNS). However, other immune cells can impact neurological conditions, principally blood-borne monocytes that can infiltrate into brain parenchyma after seizures. As such, this review will first discuss how monocytes can be recruited to the CNS and how they can be distinguished from there immunological cousins, microglia. Then, we will explore what is known about the role monocytes have within seizure pathogenesis and epilepsy. Considering how little is known about monocyte function in seizure- and epilepsy-related pathologies, further studies are warranted that investigate infiltrated blood-borne monocytes as a potential therapeutic target for epilepsy treatment.