Brain inflammation in epilepsy: experimental and clinical evidence

Elevated Blood-Based Brain Biomarker Levels in Patients with Epileptic Seizures: A Systematic Review and Meta-analysis

Recently, growing attention has been paid to the changes of brain biomarkers following the epilepsy. However, establishing specific epilepsy-related biomarkers has been impeded due to contradictory findings. This study systematically reviewed the evidence on brain biomarkers in epilepsy and determined reliable biomarkers in epileptic patients. A comprehensive systematic search of online databases was performed to find eligible studies up to August 2019. The quality of studies methodologically was assessed using the Newcastle-Ottawa Scale score. Among the several biomarkers, S100 calcium binding protein B (S100B) and neuron specific enolase (NSE) have been qualified for meta-analysis of the association between epilepsy and the brain biomarkers. Inverse-variance weights method was used to calculate pooled standardized mean difference (SMD) estimate with 95% CI, and random effects meta-analysis was conducted taking into account conceptual heterogeneity. Sensitivity analysis and publication bias assessment was performed using Stata. Of 29 studies that were qualified for further analysis, only 22 studies were eligible to quantify by meta-analysis. Significant increase of serum S100B levels (SMD = 0.80; 95% CI 0.18 to 1.42) but not NSE (SMD = 0.45; 95% CI -0.09 to 1.00) has been found in epileptic patients compared with healthy controls. Subgroup meta-analysis by age demonstrated that S100B could be found in pediatric (SMD = 1.15; 95% CI 0.03 to 2.27) not adult patients (SMD = 0.43; 95% CI -0.12 to 0.98). Findings of this meta-analysis indicate that serum level of S100B is significantly increased in epileptic patients, suggesting the elevation and release of the brain biomarkers from brain to blood following epileptic seizures.

Differential Glial Activation in Early Epileptogenesis-Insights From Cell-Specific Analysis of DNA Methylation and Gene Expression in the Contralateral Hippocampus

Background and Aims: Morphological changes in mesial temporal lobe epilepsy with hippocampal sclerosis (mTLE-HS) are well-characterized. Yet, it remains elusive whether these are a consequence of seizures or originate from a hitherto unknown underlying pathology. We recently published data on changes in gene expression and DNA methylation in the ipsilateral hippocampus (ILH) using the intracortical kainate mouse model of mTLE-HS. In order to explore the effects of epileptic activity alone and also to further disentangle what triggers morphological alterations, we investigated glial and neuronal changes in gene expression and DNA methylation in the contralateral hippocampus (CLH). Methods: The intracortical kainic acid mouse model of mTLE-HS was used to elicit status epilepticus. Hippocampi contralateral to the injection site from eight kainate-injected and eight sham mice were extracted and shock frozen at 24 h post-injection. Glial and neuronal nuclei were sorted by flow cytometry. Alterations in gene expression and DNA methylation were assessed using reduced representation bisulfite sequencing and RNA sequencing. The R package edgeR was used for statistical analysis. Results: The CLH featured substantial, mostly cell-specific changes in both gene expression and DNA methylation in glia and neurons. While changes in gene expression overlapped to a great degree between CLH and ILH, alterations in DNA methylation did not. In the CLH, we found a significantly lower number of glial genes up- and downregulated compared to previous results from the ILH. Furthermore, several genes and pathways potentially involved in anti-epileptogenic effects were upregulated in the CLH. By comparing gene expression data from the CLH to previous results from the ILH (featuring hippocampal sclerosis), we derive potential upstream targets for epileptogenesis, including glial Cox2 and Cxcl10. Conclusion: Despite the absence of morphological changes, the CLH displays substantial changes in gene expression and DNA methylation. We find that gene expression changes related to potential anti-epileptogenic effects seem to dominate compared to the pro-epileptogenic effects in the CLH and speculate whether this imbalance contributes to prevent morphological alterations like neuronal death and reactive gliosis.

Evaluation of serum high-mobility group box 1 concentration in dogs with epilepsy: A case-control study

BACKGROUND

High-mobility group box 1 (HMGB1) is a key mediator of neuroinflammation and there are increased HMGB1 levels in laboratory animal models of epilepsy and human patients with epilepsy.

OBJECTIVES

To determine serum HMGB1 levels in dogs with epilepsy.

ANIMALS

Twenty-eight epileptic dogs, 12 dogs with nonepileptic brain diseases, and 26 healthy dogs.

METHODS

In this case-control study, serum HMGB1 concentrations were estimated using the canine-specific enzyme-linked immunosorbent assay kit. Diagnosis of dogs with epilepsy was based on medical history, physical and neurological examination findings, laboratory test results, magnetic resonance image, and cerebrospinal fluid analysis.

RESULTS

Serum HMGB1 levels were significantly higher in epileptic dogs (median = 0.41 ng/mL; range, 0.03-5.28) than in healthy dogs (median = 0.12 ng/mL; range, 0.02-1.45; P = .002). In contrast, serum HMGB1 levels of dogs with non-epileptic brain diseases (median = 0.19 ng/mL; range, 0.03-1.04) were not significantly increased compared to those of healthy dogs (P = .12). Regarding idiopathic epilepsy, dogs with an epilepsy course of >3 months showed a higher serum HMGB1 concentration (median = 0.87 ng/mL; range, 0.42-2.88) than those with that of ≤3 months (median = 0.26 ng/mL; range, 0.03-0.88; P = .02).

CONCLUSIONS AND CLINICAL IMPORTANCE

Serum HMGB1 could be a biomarker of epilepsy.

MnSOD Ala16Val polymorphism in cognitive dysfunction in patients with epilepsy: A relationship with oxidative and inflammatory markers

OBJECTIVE

The objective of the study was to evaluate the neurocognitive profile and its relation with Ala16ValMnSOD polymorphism in epilepsy and if these clinical parameters are linked to oxidative stress and inflammatory markers.

METHODS

Patients with epilepsy (n = 31) and healthy subjects (n = 42) were recruited. A neuropsychological evaluation was performed in both groups through a battery of cognitive tests. Oxidative stress, inflammatory markers, apoptotic factors, and deoxyribonucleic acid (DNA) damage were measured in blood samples.

RESULTS

Statistical analyses showed the association of MnSOD Ala16Val polymorphism with cognitive impairment, including praxis, perception, attention, language, executive functions, long-term semantic memory, short-term visual memory, and total memory in patients with epilepsy and Valine-Valine (VV) genotype compared with the control group. Compared with the controls and patients with epilepsy, Alanine-Alanine (AA), and Alanine-Valine (AV) genotype, the patients with epilepsy and VV genotype exhibited higher levels of tumor necrosis factor alpha (TNF-α), interleukin 1β (IL-1β), interleukin 6 (IL-6), activation of caspases 1 and 3 (CASP-1 and -3), and DNA damage. Our findings also showed higher carbonyl protein and thiobarbituric acid reactive substances (TBARS) levels as well as an increased superoxide dismutase (SOD) and acetylcholinesterase (AChE) activities in patients with epilepsy and VV genotype.

CONCLUSION

This study supports the evidence of a distinct neuropsychological profile in patients with epilepsy, especially those with the VV genotype. Furthermore, our results suggest that oxidative and inflammatory pathways may be associated with genetic polymorphism and cognitive dysfunction in patients with epilepsy.

Anticonvulsant mechanisms of the ketogenic diet and caloric restriction

Many treatments have been proposed to control epileptic seizures, such as the ketogenic diet and caloric restriction. However, seizure control has not yet been improved completely in all patients. Probably, due to the lack of understanding regarding this neurological disorder pathogenesis or pathophysiology, including its molecular approach. Currently, there is not much information about the molecular processes and genes involved, and their relation to the possible beneficial effects of diet therapy on epilepsy. The ketogenic diet and caloric restriction are implicated in potential anti-seizure mechanisms related to the gut microbiome, metabolic pathways, hormones and neurotransmitters, mitochondria improvement, a role in inflammation, and oxidative stress, among others. In this review, we pretend to describe the molecular mechanism and the possible genes involved in the different ketogenic diet and caloric restriction mechanisms of action described to decrease neural excitability and, therefore, epileptic seizures, especially when conventional treatment is not enough to achieve control of epilepsy.

A comparative study of the phenotype with kainic acid-induced seizure in DBA/2 mice from three different sources

The kainic acid-induced seizure mouse model is widely used in epilepsy research. In this study, we applied kainic acid to the subcutaneous injections of three different sources of DBA/2 mice to compare and evaluate the seizure response. The three mouse sources consisted of DBA/2Kor1 (Korea FDA source), DBA/2A (USA source), and DBA/2 (Japan source), and were purchased from different vendors. To compare the responses of DBA/2 mice to kainic acid injections, we examined the survival rate, seizure phenotype scoring, and behavioral changes. We also evaluated brain lesions using histopathological analysis. Following the administration of kainic acid, almost half of the cohort survived, and the seizure phenotype displayed a moderate level of sensitivity (2 ~ 4 out of 6). In the histopathologic analysis, there was no change in morphological features, and levels of glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule 1 (Iba-1) increased in the kainic acid-treated groups. However, there was no difference in the neuronal nuclei (NeuN) expression level. All the data showed that the responses in the kainic acid-treated group were similar across the three strains. In conclusion, our results suggest that the three sources of DBA/2 mice (DBA/2Kor1, DBA/2A, and DBA/2B) have similar pathological responses to kainic acid-induced seizures.

Inflammatory and immune mechanisms underlying epileptogenesis and epilepsy: From pathogenesis to treatment target

Epilepsy is a brain disease associated with epileptic seizures as well as with neurobehavioral outcomes of this condition. In the last century, inflammation emerged as a crucial factor in epilepsy etiology. Various brain insults through activation of neuronal and non-neuronal brain cells initiate a series of inflammatory events. Growing observations strongly suggest that abnormal activation of critical inflammatory processes contributes to epileptogenesis, a gradual process by which a normal brain transforms into the epileptic brain. Increased knowledge of inflammatory pathways in epileptogenesis has unveiled mechanistic targets for novel antiepileptic therapies. Molecules specifically targeting the pivotal inflammatory pathways may serve as promising candidates to halt the development of epilepsy. The present paper reviews the pieces of evidence conceptually supporting the potential role of inflammatory mechanisms and the relevant blood-brain barrier (BBB) disruption in epileptogenesis. Also, it discusses the mechanisms underlying inflammation-induced neuronal-glial network impairment and highlights innovative neuroregulatory actions of typical inflammatory molecules. Finally, it presents a brief analysis of observations supporting the therapeutic role of inflammation-targeting tiny molecules in epileptic seizures.

Analyzing the Potential Biological Determinants of Autism Spectrum Disorder: From Neuroinflammation to the Kynurenine Pathway

Autism Spectrum Disorder (ASD) etiopathogenesis is still unclear and no effective preventive and treatment measures have been identified. Research has focused on the potential role of neuroinflammation and the Kynurenine pathway; here we review the nature of these interactions. Pre-natal or neonatal infections would induce microglial activation, with secondary consequences on behavior, cognition and neurotransmitter networks. Peripherally, higher levels of pro-inflammatory cytokines and anti-brain antibodies have been identified. Increased frequency of autoimmune diseases, allergies, and recurring infections have been demonstrated both in autistic patients and in their relatives. Genetic studies have also identified some important polymorphisms in chromosome loci related to the human leukocyte antigen (HLA) system. The persistence of immune-inflammatory deregulation would lead to mitochondrial dysfunction and oxidative stress, creating a self-sustaining cytotoxic loop. Chronic inflammation activates the Kynurenine pathway with an increase in neurotoxic metabolites and excitotoxicity, causing long-term changes in the glutamatergic system, trophic support and synaptic function. Furthermore, overactivation of the Kynurenine branch induces depletion of melatonin and serotonin, worsening ASD symptoms. Thus, in genetically predisposed subjects, aberrant neurodevelopment may derive from a complex interplay between inflammatory processes, mitochondrial dysfunction, oxidative stress and Kynurenine pathway overexpression. To validate this hypothesis a new translational research approach is necessary.

Intraperitoneal injection of lipopolysaccharide prevents seizure-induced respiratory arrest in a DBA/1 mouse model of SUDEP

OBJECTIVE

Sudden unexpected death in epilepsy (SUDEP) is the cause of premature death of 50% patients with chronic refractory epilepsy. Respiratory failure during seizures is regarded as an important mechanism of SUDEP. Previous studies have shown that abnormal serotonergic neurotransmission is involved in the pathogenesis of seizure-induced respiratory failure, while enhancing serotonergic neurotransmission in the brainstem suppresses it. Because peripheral inflammation is known to enhance serotonergic neuron activation and 5-HT synthesis and release, we investigated the effect of intraperitoneal lipopolysaccharide (LPS)-induced inflammation on the S-IRA susceptibility during audiogenic seizures in DBA/1 mice.

METHODS

After DBA/1 mice were primed by exposing to sound stimulation for three consecutive days, they were tested for seizure severity and seizure-induced respiratory arrest (S-IRA) induced by sound stimulation under different conditions. We determined the dose and time course of the effects of intraperitoneal administration of LPS on audiogenic seizures and S-IRA. The effects of blocking TLR4 or RAGE receptors and blocking 5-HT receptors on the LPS-induced effect on S-IRA were investigated. Statistical significance was evaluated using the Kruskal-Wallis test.

RESULTS

Intraperitoneal injection of LPS significantly had dose-dependent effects in reducing the incidence of S-IRA as well as seizure severity in DBA/1 mice. The protective effect of LPS on S-IRA peaked at 8-12 hours after LPS injection and was related to both reducing seizure severity and enhancing autoresuscitation. Blocking TLR4 or RAGE receptor with TAK-242 or FPS-ZM1, respectively, prior to LPS injection attenuated its effects on S-IRA and seizure severity. Injection of a nonselective 5-HT receptor antagonist, cyproheptadine, or a 5-HT3 receptor antagonist, ondansetron, was effective in blocking LPS-induced effect on S-IRA. Immunostaining results showed a significant increase in c-Fos-positive serotonergic neurons in the dorsal raphe.

SIGNIFICANCE

This is the first study that demonstrates the effect of intraperitoneal LPS injection-induced inflammation on reducing S-IRA susceptibility and provides additional evidence supporting the serotonin hypothesis on SUDEP. Our study suggests that inflammation may enhance brainstem 5-HT neurotransmission to promote autoresuscitation during seizure and prevent SUDEP.

Blood biomarkers predictive of epilepsy after an acute stroke event

OBJECTIVE

Blood biomarkers have not been widely investigated in poststroke epilepsy. In this study, we aimed to describe clinical factors and biomarkers present during acute stroke and analyze their association with the development of epilepsy at long term.

METHODS

A panel of 14 blood biomarkers was evaluated in patients with ischemic and hemorrhagic stroke. Biomarkers were normalized and standardized using Z-scores. Stroke and epilepsy-related variables were also assessed: stroke severity, determined by National Institutes of Health Stroke Scale (NIHSS) score, stroke type and cause, time from stroke to onset of late seizures, and type of seizure. Multiple Cox regression models were used to identify clinical variables and biomarkers independently associated with epilepsy.

RESULTS

From a cohort of 1115 patients, 895 patients were included. Mean ± standard deviation (SD) age was 72.0 ± 13.1 years, and 57.8% of patients were men. Fifty-one patients (5.7%) developed late seizures, with a median time to onset of 232 days (interquartile range [IQR] 86-491). NIHSS score ≥8 (P < .001, hazard ratio [HR] 4.013, 95% confidence interval [CI] 2.123-7.586) and a history of early onset seizures (P < .001, HR 4.038, 95% CI 1.802-9.045) were factors independently associated with a risk of developing epilepsy. Independent blood biomarkers predictive of epilepsy were high endostatin levels >1.203 (P = .046, HR 4.300, 95% CI 1.028-17.996) and low levels of heat shock 70 kDa protein-8 (Hsc70) <2.496 (P = .006, HR 3.795, 95% CI 1.476-9.760) and S100B <1.364 (P = .001, HR 2.955, 95% CI 1.534-5.491). The risk of epilepsy when these biomarkers were combined increased to 17%. The area under the receiver-operating characteristic (ROC) curve of the predictive model was stronger when clinical variables were combined with blood biomarkers (74.3%, 95% CI 65.2%-83.3%) than when they were used alone (68.9%, 95% CI 60.3%-77.6%).

SIGNIFICANCE

Downregulated S100B and Hsc70 and upregulated endostatin may assist in prediction of poststroke epilepsy and may provide additional information to clinical risk factors. In addition, these data are hypothesis-generating for the epileptogenic process.

Loss of Protection by Antiepileptic Drugs in Lipopolysaccharide-primed Pilocarpine-induced Status Epilepticus is Mediated via Inflammatory Signalling

The evidences from various studies show the association of peripheral and neuronal inflammation with complex pathophysiology of status epilepticus (SE). In this view, the present work attempted to develop a model of neuronal inflammation mediated SE by combining both epileptic and inflammatory components of the disease and also to mimic SE co-morbid with systemic inflammation by peripheral administration of the lipopolysaccharide (LPS) 2 h prior to the pilocarpine (PILO) induction in C57BL/6 mice. We evaluated the anti-convulsant and neuroprotective effects of 7-day prophylactic treatment with three conventional anti-epileptic drugs (Sodium valproate, SVP 300 mg/kg p.o.; Carbamazepine CBZ 100 mg/kg p.o.; Levetiracetam; LEV 200 mg/kg p.o.) of widespread clinical use. Morris water maze and Rota rod tests were carried out 24-h post-exposure to evaluate the neurobehavioral co-morbidities associated with neuroinflammation-mediated status epilepticus. Upon priming with LPS, the loss of protection against PILO-induced seizures was observed by SVP and CBZ, however, LEV showed protection by delaying the seizures. Dramatic elevation in the seizure severity and neuronal loss demonstrated the possible pro-convulsant effect of LPS in the PILO model. Also, the decreased cytokine levels by the AEDs showed their association with NF-κB, IL-1β, IL-6, TNF-α and TGF-β pathways in PILO model. The loss of protective activities of SVP and CBZ in LPS+PILO model was due to increased cytokine levels associated with over-activation of neuroinflammatory pathways, however, partial efficacy of LEV is possibly due to association of other neuroinflammatory mechanisms. The current work provides direct evidence of the contribution of increased peripheral and neuronal inflammation in seizures via regulation of inflammatory pathways in the brain.

Modulating neuroinflammation and oxidative stress to prevent epilepsy and improve outcomes after traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability in young adults worldwide. TBI survival is associated with persistent neuropsychiatric and neurological impairments, including posttraumatic epilepsy (PTE). To date, no pharmaceutical treatment has been found to prevent PTE or ameliorate neurological/neuropsychiatric deficits after TBI. Brain trauma results in immediate mechanical damage to brain cells and blood vessels that may never be fully restored given the limited regenerative capacity of brain tissue. This primary insult unleashes cascades of events, prominently including neuroinflammation and massive oxidative stress that evolve over time, expanding the brain injury, but also clearing cellular debris and establishing homeostasis in the region of damage. Accumulating evidence suggests that oxidative stress and neuroinflammatory sequelae of TBI contribute to posttraumatic epileptogenesis. This review will focus on possible roles of reactive oxygen species (ROS), their interactions with neuroinflammation in posttraumatic epileptogenesis, and emerging therapeutic strategies after TBI. We propose that inhibitors of the professional ROS-generating enzymes, the NADPH oxygenases and myeloperoxidase alone, or combined with selective inhibition of cyclooxygenase mediated signaling may have promise for the treatment or prevention of PTE and other sequelae of TBI. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.

Methylprednisolone pulse therapy in 31 patients with refractory epilepsy: A single-center retrospective analysis

PURPOSE

We investigated the efficacy of methylprednisolone pulse therapy (MP) and responder characteristics in patients with refractory epilepsy.

METHODS

We reviewed medical records of our center to identify patients with refractory epilepsy treated with MP other than continuous spikes and waves during slow sleep (CSWS), Landau-Kleffner syndrome (LKS), or Rasmussen's syndrome (RS) between 2004 and 2015. A course of MP consisted of intravenous methylprednisolone (30 mg/kg/day) on three consecutive days. Patients received multiple courses at intervals of four weeks. We examined seizure outcome, developmental outcome, antibodies to N-methyl-d-aspartate (NMDA)-type glutamate receptors (GluRs), cerebral spinal fluid (CSF)-albumin/serum-albumin ratio, and interictal electroencephalograms (EEGs). Responder to MP was defined as maintaining seizure reduction rate (SRR) ≥50% for three months after the first course of MP.

RESULTS

Thirty-one consecutive patients treated with MP at our center were studied. Seizure types were focal onset impaired awareness seizure (FIAS) only (n = 23), FIAS with epileptic spasms (ES) (n = 7), and ES only (n = 1). Responder rate was 32.2% (10/31 patients), and seizure-free rate was 9.7% (3/31). Responders constituted 43.5% of patients without ES. No patient with ES was responder. Behavior and cognition also improved in 6 of 10 responders. History of seizure aggravation after inactivated vaccine before MP was found significantly higher rate in responder patients, comparing with nonresponder patients (p = 0.01).

CONCLUSION

Methylprednisolone pulse therapy may be considered for possible treatment in patients with focal epilepsy with drug-resistant seizures without ES, and it may improve cognitive function and behavioral comorbidities.

Modeling epileptic spasms during infancy: Are we heading for the treatment yet?

Infantile spasms (IS or epileptic spasms during infancy) were first described by Dr. William James West (aka West syndrome) in his own son in 1841. While rare by definition (occurring in 1 per 3200-3400 live births), IS represent a major social and treatment burden. The etiology of IS varies - there are many (>200) different known pathologies resulting in IS and still in about one third of cases there is no obvious reason. With the advancement of genetic analysis, role of certain genes (such as ARX or CDKL5 and others) in IS appears to be important. Current treatment strategies with incomplete efficacy and serious potential adverse effects include adrenocorticotropin (ACTH), corticosteroids (prednisone, prednisolone) and vigabatrin, more recently also a combination of hormones and vigabatrin. Second line treatments include pyridoxine (vitamin B6) and ketogenic diet. Additional treatment approaches use rapamycin, cannabidiol, valproic acid and other anti-seizure medications. Efficacy of these second line medications is variable but usually inferior to hormonal treatments and vigabatrin. Thus, new and effective models of this devastating condition are required for the search of additional treatment options as well as for better understanding the mechanisms of IS. Currently, eight models of IS are reviewed along with the ideas and mechanisms behind these models, drugs tested using the models and their efficacy and usefulness. Etiological variety of IS is somewhat reflected in the variety of the models. However, it seems that for finding precise personalized approaches, this variety is necessary as there is no "one-size-fits-all" approach possible for both IS in particular and epilepsy in general.

The Runx1/Notch1 Signaling Pathway Participates in M1/M2 Microglia Polarization in a Mouse Model of Temporal Lobe Epilepsy and in BV-2 Cells

Microglial activation and phenotypic shift play vital roles in many neurological diseases. Runt-related transcription factor-1 (Runx1), which is localized on microglia, inhibits amoeboid microglial proliferation. Preliminary data have indicated that the interaction of Runx1 with the Notch1 pathway affects the hemogenic endothelial cell shift. However, little is known about the effect of Runx1 and the Notch1 signaling pathway on the phenotypic shift of microglia during neuroinflammation, especially in temporal lobe epilepsy (TLE). A mouse model of TLE induced by pilocarpine and the murine microglia cell line BV-2 were used in this study. The proportion of microglia was analyzed using flow cytometry. Western blot (WB) analysis and quantitative real-time polymerase chain reaction were used to analyze protein and gene transcript levels, respectively. Immunohistochemistry was used to show the distribution of Runx1. In the present study, we first found that in a male mouse model of TLE induced by pilocarpine, flow cytometry revealed a time-dependent M2-to-M1 microglial transition after status epilepticus. The dynamic expression patterns of Runx1 and the downstream Notch1/Jagged1/Hes5 signaling pathway molecules in the epileptic hippocampus were determined. Next, Runx1 knockdown by small interfering RNA in BV-2 cells strongly promoted an M2-to-M1 microglial phenotype shift and inhibited Notch1/Jagged1/Hes5 pathway expression. In conclusion, Runx1 may play a critical role in the M2-to-M1 microglial phenotype shift via the Notch1 signaling pathway during epileptogenesis in a TLE mouse model and in BV-2 cells.

Tumor Necrosis Factor-α, the Pathological Key to Post-Traumatic Epilepsy: A Comprehensive Systematic Review

Post-traumatic epilepsy (PTE) is one of the detrimental outcomes of traumatic brain injury (TBI), resulting in recurrent seizures that impact daily life. However, the pathological relationship between PTE and TBI remains unclear, and commonly prescribed antiepileptic drugs (AED) are ineffective against PTE. Fortunately, emerging research implicates neuroinflammation, particularly, tumor necrosis factor-α (TNF-α), as the key mediator for PTE development. Thus, this review aims to examine the available literature regarding the role of TNF-α in PTE pathology and, subsequently, evaluate TNF-α as a possible target for its treatment. A comprehensive literature search was conducted on four databases including PubMed, CINAHL, Embase, and Scopus. Articles with relevance in investigating TNF-α expression in PTE were considered in this review. Critical evaluation of four articles that met the inclusion criteria suggests a proportional relationship between TNF-α expression and seizure susceptibilit and that neutralization or suppression of TNF-α release results in reduced susceptibility to seizures. In conclusion, this review elucidates the importance of TNF-α expression in epileptogenesis postinjury and urges future research to focus more on clinical studies involving TNF-α, which may provide clearer insight into PTE prevention, therefore improving the lives of PTE patients.

Protective effects of maternal administration of curcumin and hesperidin in the rat offspring following repeated febrile seizure: Role of inflammation and TLR4

Neuroinflammation has a key role in seizure generation and perpetuation in the neonatal period, and toll-like receptor 4 (TLR4) pathway has a prominent role in neuroinflammatory diseases. Administration of antioxidants and targeting TLR4 in the embryonic period may protect rat offspring against the next incidence of febrile seizure and its harmful effects. Curcumin and hesperidin are natural compounds with anti-inflammatory and antioxidant properties and have an inhibitory action on TLR4 receptors. We evaluated the effect of maternal administration of curcumin and hesperidin on infantile febrile seizure and subsequent memory dysfunction in adulthood. Hyperthermia febrile seizure was induced on postnatal days 9-11 on male rat pups with 24 h intervals, in a Plexiglas box that was heated to ~45 °C by a heat lamp. We used enzyme-linked immunosorbent assay, Western blotting, malondialdehyde (MDA), and glutathione (GSH) assessment for evaluation of inflammatory cytokine levels, TLR4 protein expression, and oxidative responses in the hippocampal tissues. For assessing working memory and long-term potentiation, the double Y-maze test and Schaffer collateral-CA1 in vivo electrophysiological recording were performed, respectively Our results showed that curcumin and hesperidin decreased TNF-α, IL-10, and TLR4 protein expression and reversed memory dysfunction. However, they did not provoke a significant effect on GSH content or amplitude and slope of recorded fEPSPs in the hippocampus. In addition, curcumin, but not hesperidin, decreased interleukin-1β (IL-1β) and MDA levels. These findings imply that curcumin and hesperidin induced significant protective effects on febrile seizures, possibly via their anti-inflammatory and antioxidant properties and downregulation of TLR4.

Revisiting the Impact of Neurodegenerative Proteins in Epilepsy: Focus on Alpha-Synuclein, Beta-Amyloid, and Tau

Lack of disease-modifying therapy against epileptogenesis reflects the complexity of the disease pathogenesis as well as the high demand to explore novel treatment strategies. In the pursuit of developing new therapeutic strategies against epileptogenesis, neurodegenerative proteins have recently gained increased attention. Owing to the fact that neurodegenerative disease and epileptogenesis possibly share a common underlying mechanism, targeting neurodegenerative proteins against epileptogenesis might represent a promising therapeutic approach. Herein, we review the association of neurodegenerative proteins, such as α-synuclein, amyloid-beta (Aβ), and tau protein, with epilepsy. Providing insight into the α-synuclein, Aβ and tau protein-mediated neurodegeneration mechanisms, and their implication in epileptogenesis will pave the way towards the development of new agents and treatment strategies.

Neurodegenerative pathways as targets for acquired epilepsy therapy development

There is a growing body of clinical and experimental evidence that neurodegenerative diseases and epileptogenesis after an acquired brain insult may share common etiological mechanisms. Acquired epilepsy commonly develops as a comorbid condition in patients with neurodegenerative diseases such as Alzheimer's disease, although it is likely much under diagnosed in practice. Progressive neurodegeneration has also been described after traumatic brain injury, stroke, and other forms of brain insults. Moreover, recent evidence has shown that acquired epilepsy is often a progressive disorder that is associated with the development of drug resistance, cognitive decline, and worsening of other neuropsychiatric comorbidities. Therefore, new pharmacological therapies that target neurobiological pathways that underpin neurodegenerative diseases have potential to have both an anti-epileptogenic and disease-modifying effect on the seizures in patients with acquired epilepsy, and also mitigate the progressive neurocognitive and neuropsychiatric comorbidities. Here, we review the neurodegenerative pathways that are plausible targets for the development of novel therapies that could prevent the development or modify the progression of acquired epilepsy, and the supporting published experimental and clinical evidence.

The role of nitric oxide in glutaric acid-induced convulsive behavior in pup rats

Glutaric acidaemia type I (GA-I) is a cerebral organic disorder characterized by the accumulation of glutaric acid (GA) and seizures. As seizures are precipitated in children with GA-I and the mechanisms underlying this disorder are not well established, we decided to investigate the role of nitric oxide (NO) in GA-induced convulsive behaviour in pup rats. Pup male Wistar rats (18-day-old) were anesthetized and placed in stereotaxic apparatus for cannula insertion into the striatum for injection of GA. The experiments were performed 3 days after surgery (pup rats 21-day-old). An inhibitor of NO synthesis (N-G-nitro-l-arginine methyl ester-L-NAME, 40 mg/kg) or saline (vehicle) was administered intraperitoneally 30 min before the intrastriatal injection of GA (1 µl, 1.3 µmol/striatum) or saline. Immediately after the intrastriatal injections, the latency and duration of seizures were recorded for 20 min. The administration of L-NAME significantly increased the latency to the first seizure episode and reduced the duration of seizures induced by GA in pup rats. The administration of the NO precursor l-arginine (L-ARG; 80 mg/kg) prevented the effects of L-NAME. Besides, GA significantly increased nitrate and nitrite (NOx) levels in the striatum of pup rats and the preadministration of L-NAME prevented this alteration. L-ARG blocked the reduction of striatal NOx provoked by L-NAME. These results are experimental evidence that NO plays a role in the seizures induced by GA in pup rats, being valuable in understanding the physiopathology of neurological signs observed in children with this organic acidaemia and to develop new therapeutic strategies.

Effects of Diclofenac Versus Meloxicam in Pentylenetetrazol-Kindled Mice

Epilepsy comes after stroke as the most common chronic neurological disorder worldwide. Inflammation enhances neuronal hyperexcitability that could provide a background setting for the development of epilepsy. The aim of this study was to assess the effect of valproate (VAL), diclofenac (DIC), meloxicam (MEL), VAL + MEL and VAL + DIC in pentylenetetrazol (PTZ) kindled mice. Seventy mice were randomly allocated into 7 equal groups; Control, PTZ, VAL, DIC, MEL, VAL + MEL and VAL + DIC groups. Kindling was induced by PTZ (40 mg/kg, i.p.) injection every other day for 17 days. The drugs were administered, 30 min before each PTZ injection till the end of the schedule. Seizure score, latency, duration and mortality rate were recorded in all groups. Tumor necrosis factor- α (TNF-α), interleukin-1β (IL-1β), malondialdehyde (MDA) and prostaglandin E2 (PGE2) levels as well as reduced glutathione (GSH) content were assessed in brain homogenate at the end of the schedule. VAL, DIC, MEL, VAL + MEL and VAL + DIC decreased seizure score and duration. Meanwhile, they increased the latency period. PTZ increased TNF-α, IL-1β, MDA, and PGE2 levels meanwhile, it decreased GSH content. Administration of VAL, DIC, MEL, VAL + MEL and VAL + DIC decreased TNF-α, IL-1β, MDA, and PGE2 levels meanwhile, they increased GSH content in the brain homogenates. Effects of VAL + DIC combination on the studied parameters were significant in relation to VAL. VAL, DIC, MEL, VAL + MEL and VAL + DIC produced anticonvulsant effect and mitigated inflammation and oxidative stress in PTZ-kindled mice. Interestingly, DIC rather than MEL enhanced the anticonvulsant effect VAL.

Neuroinflammation impact in epileptogenesis and new treatment strategy

Epilepsy is considered a major serious chronic neurological disorder, characterized by recurrent seizures. It is usually associated with a history of a lesion in the nervous system. Irregular activation of inflammatory molecules in the injured tissue is an important factor in the development of epilepsy. It is unclear how the imbalanced regulation of inflammatory mediators contributes to epilepsy. A recent research goal is to identify interconnected inflammation pathways which may be involved in the development of epilepsy. The clinical use of available antiepileptic drugs is often restricted by their limitations, incidence of several side effects, and drug interactions. So development of new drugs, which modulate epilepsy through novel mechanisms, is necessary. Alternative therapies and diet have recently reported positive treatment outcomes in epilepsy. Vitamin D (Vit D) has shown prophylactic and therapeutic potential in different neurological disorders. So, the aim of current study was to review the associations between different brain inflammatory mediators and epileptogenesis, to strengthen the idea that targeting inflammatory pathway may be an effective therapeutic strategy to prevent or treat epilepsy. In addition, neuroprotective effects and mechanisms of Vit D in clinical and preclinical studies of epilepsy were reviewed.

Neuroprotective and anticonvulsant effects of sinomenine in kainate rat model of temporal lobe epilepsy: Involvement of oxidative stress, inflammation and pyroptosis

Oxidative stress, inflammation and pyroptosis are three of the most important mechanisms in the pathophysiology of temporal lobe epilepsy (TLE). Most people with TLE are refractory to the existing drugs. Sinomenine has shown neuroprotective effects through counteracting oxidative stress, inflammation and pyroptosis. In this study, we evaluated the effect of sinomenine on seizure behavior, oxidative stress, inflammation and pyroptosis markers in addition to its neuroprotective potential in intrahippocampal kainate-induced rat model of TLE. For this purpose, male rats (n = 60) were randomly divided into five groups, i.e., sham, kainate (lesion) with an intrahippocampal injection of kainate, kainate groups receiving sinomenine at doses of 30 or 50 mg/kg, and kainate group receiving valproic acid at a dose of 200 mg/kg (as the positive control). Our obtained data showed that sinomenine administration at a dose of 50 mg/kg can significantly decreases severity of seizures and incidence of status epilepticus (SE), hippocampal aberrant MFS and DNA fragmentation and prevents reduction of neuronal density. It also significantly restored level of ROS, MDA, HO-1 and SOD but its effect on GSH level was not significant. Additionally, sinomenine at a dose of 50 mg/kg partially counteracted the increase of NF-κB, TLR 4, TNFα, GFAP and caspase 1. These results suggest that sinomenine has anticonvulsant and neuroprotective effects by reducing hippocampal oxidative stress, inflammation, pyroptosis and apoptosis in intrahippocampal kainate model of TLE.

Epileptogenesis and oncogenesis: An antineoplastic role for antiepileptic drugs in brain tumours?

The first description of epileptic seizures due to brain tumours occurred in 19th century. Nevertheless, after over one hundred years, scientific literature is still lacking on how epilepsy and its treatment can affect tumour burden, progression and clinical outcomes. In patients with brain tumours, epilepsy dramatically impacts their quality of life (QoL). Even antiepileptic therapy seems to affect tumor lesion development. Numerous studies suggest that certain actors involved in epileptogenesis (inflammatory changes, glutamate and its ionotropic and metabotropic receptors, GABA-A and its GABA-AR receptor, as well as certain ligand- and voltage-gated ion channel) may also contribute to tumorigenesis. Although some antiepileptic drugs (AEDs) are known operating on such mechanisms underlying epilepsy and tumor development, few preclinical and clinical studies have tried to investigate them as targets of pharmacological tools acting to control both phenomena. The primary aim of this review is to summarize known determinants and pathophysiological mechanisms of seizures, as well as of cell growth and spread, in patients with brain tumors. Therefore, a special focus will be provided on the anticancer effects of commonly prescribed AEDs (including levetiracetam, valproic acid, oxcarbazepine and others), with an overview of both preclinical and clinical data. Potential clinical applications of this finding are discussed.

Pilocarpine Induced Behavioral and Biochemical Alterations in Chronic Seizure-Like Condition in Adult Zebrafish

Epilepsy is a devastating neurological condition exhibited by repeated spontaneous and unpredictable seizures afflicting around 70 million people globally. The basic pathophysiology of epileptic seizures is still elusive, reflecting an extensive need for further research. Developing a novel animal model is crucial in understanding disease mechanisms as well as in assessing the therapeutic target. Most of the pre-clinical epilepsy research has been focused on rodents. Nevertheless, zebrafish disease models are relevant to human disease pathophysiology hence are gaining increased attention nowadays. The current study for the very first time developed a pilocarpine-induced chronic seizure-like condition in adult zebrafish and investigated the modulation in several neuroinflammatory genes and neurotransmitters after pilocarpine exposures. Seizure score analysis suggests that compared to a single dose, repeated dose pilocarpine produces chronic seizure-like effects maintaining an average seizure score of above 2 each day for a minimum of 10 days. Compared to the single dose pilocarpine treated group, there was increased mRNA expression of HMGB1, TLR4, TNF-α, IL-1, BDNF, CREB-1, and NPY; whereas decreased expression of NF-κB was upon the repeated dose of pilocarpine administration. In addition, the epileptic group demonstrates modulation in neurotransmitters levels such as GABA, Glutamate, and Acetylcholine. Moreover, proteomic profiling of the zebrafish brain from the normal and epileptic groups from LCMS/MS quantification detected 77 and 13 proteins in the normal and epileptic group respectively. Summing up, the current investigation depicted that chemically induced seizures in zebrafish demonstrated behavioral and molecular alterations similar to classical rodent seizure models suggesting the usability of adult zebrafish as a robust model to investigate epileptic seizures.

HMGB1 Is a Therapeutic Target and Biomarker in Diazepam-Refractory Status Epilepticus with Wide Time Window

Status epilepticus (SE), a life-threatening neurologic emergency, is often poorly controlled by the current pharmacological therapeutics, which are limited to a narrow time window. Here, we investigated the proinflammatory cytokine high mobility group box-1 (HMGB1) as a candidate therapeutic target for diazepam (DZP)-refractory SE. We found that HMGB1 was upregulated and translocated rapidly during refractory SE period. Exogenous HMGB1 was sufficient to directly induce DZP-refractory SE in nonrefractory SE. Neutralization of HMGB1 with an anti-HMGB1 monoclonal antibody decreased the incidence of SE and alleviated the severity of seizure activity in DZP-refractory SE, which was mediated by a Toll-like receptor 4 (TLR4)-dependent pathway. Importantly, anti-HMGB1 mAb reversed DZP-refractory SE with a wide time window, extending the therapeutic window from 30 to 180 min. Furthermore, we found the upregulation of plasma HMGB1 level is closely correlated with the therapeutic response of anti-HMGB1 mAb in DZP-refractory SE. All these results indicated that HMGB1 is a potential therapeutic target and a useful predictive biomarker in DZP-refractory SE.

Dynorphin activation of kappa opioid receptor promotes microglial polarization toward M2 phenotype via TLR4/NF-κB pathway

Background

Microglia-mediated neuroinflammation is associated with epilepsy. Switching microglial polarization from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype represents a novel therapeutic strategy for mitigating epileptogenesis. We previously found that dynorphins protected against epilepsy via activation of kappa opioid receptor (KOR). Here, this study aims to investigate the role and the mechanism of dynorphin in regulating microglial polarization.

Methods

A pilocarpine-induced rat model of epilepsy was established and lipopolysaccharide (LPS)-activated BV-2 microglial cells were used as an inflammatory model to explore the mechanism of dynorphin regulating microglial polarization.

Results

Overexpression of the dynorphin precursor protein prodynorphin (PDYN) alleviated the pilocarpine-induced neuronal apoptosis, promoted microglial polarization to the M2 phenotype, and inhibited pilocarpine-induced Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) pathway in the hippocampi of epileptic rats. Dynorphin activation of KOR promoted microglial M2 polarization via inhibiting TLR4/NF-κB pathway in LPS-stimulated BV-2 microglial cells. Moreover, dynorphin/KOR regulated microglial M2 polarization inhibited apoptosis of the primary mouse hippocampal neurons.

Conclusion

In conclusion, dynorphin activation of KOR promotes microglia polarization toward M2 phenotype via inhibiting TLR4/NF-κB pathway.

Novel effect of Arthrocen (avocado/soy unsaponifiables) on pentylenetetrazole-induced seizure threshold in mice: Role of GABAergic pathway

Arthrocen, an avocado/soy unsaponifiable (ASU)-containing agent, is now used in the clinic and has potentially to decrease joint inflammation and pain associated with mild to severe osteoarthritis. Phytosterols are the major component of Arthrocen with documented anti-inflammatory properties, antioxidant, and analgesic effects. Here, we evaluated ASU anticonvulsant effect by its oral administration in pentylenetetrazole (PTZ)-induced seizure threshold and Maximal Electroshock Seizure (MES) Models. Also, the involvement of N-methyl-d-aspartate (NMDA) receptor, benzodiazepine receptor, and nitric oxide (NO) pathway were studied in anticonvulsant effect of ASU in male NMRI mice. Acute administration of Arthrocen (150, 75, 30, 10 mg/kg) by oral gavage significantly (p < 0.001) increased the clonic seizure threshold induced by intravenous administration of PTZ. Nonspecific inducible NO synthase (NOS) inhibitor L-NAME (10 mg/kg) and a specific NMDA receptor antagonist MK-801 (0.05 mg/kg) did not affect the anticonvulsant effect of Arthrocen, while pretreatment with flumazenil (0.25 mg/kg), a selective benzodiazepine receptor antagonist, reversed this effect (p < 0.01). Also, Arthrocen treated mice did not affect tonic hindlimb extension in the MES model. The data showed that Arthrocen might produce its anticonvulsant effect by enhancing GABAergic neurotransmission and/or action in the brain.

The single nucleotide variant n.60G>C in the microRNA-146a associated with susceptibility to drug-resistant epilepsy

OBJECTIVE

The aim of this study was to evaluate single nucleotide variants (SNVs) n.-411A > G (rs57095329) and n.60 G > C (rs2910164) in microRNA (miR)-146a, related to suppressing of TRAF6 with risk for epilepsy, as well as miR-146a and TRAF6 levels.

METHODS

DNAs were extracted from epileptogenic tissues and blood leukocytes from drug-resistant epilepsy patients and healthy-individuals, respectively. Genotypes were identified by real-time PCR. Hardy-Weinberg equilibrium (HWE) and Fisher or X² tests evaluated the difference between groups. The disease risk was assessed by odds ratio (OR) with 95 % confidence interval (95 %CI). The prognostic impact on probability seizure-free survival (PSF) was evaluated by Kaplan-Meier and log-rank tests.

RESULTS

For rs57095329 both control and patient samples were not in HWE (p < 0.05) and the genotypes prevalence was similar in patients and controls (p>0.05). For rs2910164, control samples were in HWE (p = 0.61), contrasting with patients (p = 0.03), and similar frequencies of wild-type homozygous (GG) (43.4 % vs. 34.4 %, p = 0.2) and variant (CC) genotypes (8.0 % vs. 6.6 %, p = 0.6) were observed in patients and controls, respectively. However, increased frequency of heterozygous (GC) was observed in patients compared to controls (59.0 % vs. 42.7 %, p = 0.04) with 1.98 (95 %CI=1.09-3.57) risk for epilepsy. The miR-146a expression level in the epileptogenic tissues was lower in the GC (p = 0.02) and CC (p = 0.09) compared to GG genotype. TRAF6 expression level was higher in CC than in GG genotype (p = 0.09). Interestingly, there was an increased frequency of patients harboring GC genotype and less time until surgery compared to patients harboring GG or CC (36.06 % vs. 11.5 %, p = 0.01), confirmed by PSF (p = 0.04).

CONCLUSIONS

The GC genotype for SNV rs2910164 appears associated with susceptibility to drug-resistant epilepsy due to the decreased MIR146a expression, favoring NF-kB pathway through TRAF6.

Inflammatory markers in the hippocampus after audiogenic kindling

Here, we investigated the participation of pro and anti-inflammatory cytokines in the spread of repeated audiogenic seizures from brainstem auditory structures to limbic areas, including the hippocampus. We used Wistar Audiogenic Rats (WARs) and Wistars submitted to the audiogenic kindling protocol with a loud broad-band noise. We measured pro and anti-inflammatory cytokines and nitrate levels in the hippocampus of stimulated animals. Our results show that all WARs developed audiogenic seizures that evolved to limbic seizures whereas seizure-resistant controls did not present any seizures. However, regardless of seizure severity, we did not observe differences in the pro inflammatory cytokines IL-1β, IL-6, TNF-α and IFN-α or in the anti-inflammatory IL-10 in the hippocampi of audiogenic and resistant animals. We also did not find any differences in nitrate content. Our data indicate that the spread of seizures during the audiogenic kindling is not dependent on hippocampal release of cytokines or oxidative stress, but the severity of brainstem seizures will be higher in animals with higher levels of cytokines and the oxidative stress marker, nitrate.

The prevalence, characteristics and outcome of seizure in tuberculous meningitis

Seizures are a common finding in patients with tuberculous meningitis (TBM), and associate with four times increased risk of death and neurological disability, especially in children. It has been reported that brain inflammation, diffuse neuronal injury, and reactive gliosis may all contribute to the pathogenesis of seizures in TBM. Early seizure onset may be associated with meningeal irritation and cerebral oedema; while, the late seizures are usually due to infarction, hydrocephalus, tuberculoma and paradoxical response. Moreover, recurrent uncontrolled seizures can evolve to status epileptics resulting in an increased risk of chronic epilepsy and poor prognosis. Therefore, this review aimed to assess the frequency of seizures in patients with TBM, and discuss the etiologies, mechanisms, and characteristics of seizures in TBM. Besides, we have searched the literature to identify the prognostic factors for chronic epilepsy after TBM.

Elevated Serum Matrix Metalloproteinase-9, Interleukin-6, Hypersensitive C-Reactive Protein, and Homocysteine Levels in Patients with Epilepsy

Neuroinflammation contributes to the occurrence and development of epilepsy. However, several inflammatory factors that are important for facilitating the diagnosis to reduce or prevent seizures need to be further studied. This study is aimed to explore serum levels of matrix metalloproteinase-9 (MMP-9), interleukin-6 (IL-6), hypersensitive C-reactive protein (hs-CRP), and homocysteine (HCY) in epilepsy patients and the relationship of them with epilepsy. Epilepsy patients (n = 101) in the Second Xiangya Hospital from January 2017 to August 2018 were allocated to the epilepsy groups, which were divided into idiopathic epilepsy group (n = 43) and symptomatic epilepsy group (n = 58) according to the pathogeny. Healthy individuals (n = 50) were allocated to the control group. The concentrations of serum MMP-9, IL-6, hs-CRP, and HCY in all samples were detected by enzyme-linked immunosorbent assay, chemiluminescence method, latex-enhanced immunoturbidimetry, and enzyme circulation method. The levels of serum MMP-9, IL-6, hs-CRP, and HCY in epilepsy patients were higher than those in the control group (P < 0.05, P < 0.01, P < 0.01, and P < 0.01, respectively). The levels of serum MMP-9, IL-6, hs-CRP, and HCY in the symptomatic epilepsy group were higher than those in the control group (P < 0.01 or P < 0.05, respectively). The levels of serum MMP-9, IL-6, and hs-CRP in idiopathic epilepsy patients were higher than those in the control group (P < 0.01 or P < 0.05, respectively). The serum HCY level in the idiopathic epilepsy group was lower than that in the symptomatic epilepsy group (P < 0.01). MMP-9, IL-6, hs-CRP, and HCY may be recommended as the state biomarker to distinguish etiology of epilepsy. We hope our study could provide help in some ways for clinical diagnosis and treatment.

Peripheral blood gene expression signatures associated with epilepsy and its etiologic classification

Heterogeneity in epilepsy often interferes with its diagnosis as well as treatment. To examine this heterogeneity at transcriptomic level, we performed whole-genome mRNA expression profiling in whole blood samples from 34 patients with epilepsy (PWE) (idiopathic, n = 13; cryptogenic, n = 9; and symptomatic, n = 12) and 41 healthy controls (HC) using Illumina HT-12 Expression Beadchip v4 microarray. In silico analysis using R software identified 165 genes to be significantly differentially expressed in PWE compared to HC (fold change>1.3, p < 0.05). Hierarchical clustering of resultant DEGs segregated idiopathic epilepsy from the rest of the epilepsy classes as well as HC. The class also displayed the most differential expression pattern with the highest number of DEGs among the three epilepsy classes. Gene ontology analysis revealed several biologically relevant inflammatory and other immune-related pathways. Our study provides insight into the relevance of altered blood gene expression patterns in understanding epilepsy and its etiologic classes.

Neuronal and glial DNA methylation and gene expression changes in early epileptogenesis

BACKGROUND AND AIMS

Mesial Temporal Lobe Epilepsy is characterized by progressive changes of both neurons and glia, also referred to as epileptogenesis. No curative treatment options, apart from surgery, are available. DNA methylation (DNAm) is a potential upstream mechanism in epileptogenesis and may serve as a novel therapeutic target. To our knowledge, this is the first study to investigate epilepsy-related DNAm, gene expression (GE) and their relationship, in neurons and glia.

METHODS

We used the intracortical kainic acid injection model to elicit status epilepticus. At 24 hours post injection, hippocampi from eight kainic acid- (KA) and eight saline-injected (SH) mice were extracted and shock frozen. Separation into neurons and glial nuclei was performed by flow cytometry. Changes in DNAm and gene expression were measured with reduced representation bisulfite sequencing (RRBS) and mRNA-sequencing (mRNAseq). Statistical analyses were performed in R with the edgeR package.

RESULTS

We observed fulminant DNAm- and GE changes in both neurons and glia at 24 hours after initiation of status epilepticus. The vast majority of these changes were specific for either neurons or glia. At several epilepsy-related genes, like HDAC11, SPP1, GAL, DRD1 and SV2C, significant differential methylation and differential gene expression coincided.

CONCLUSION

We found neuron- and glia-specific changes in DNAm and gene expression in early epileptogenesis. We detected single genetic loci in several epilepsy-related genes, where DNAm and GE changes coincide, worth further investigation. Further, our results may serve as an information source for neuronal and glial alterations in both DNAm and GE in early epileptogenesis.

A Switch to Polyunsaturated Fatty Acid Based Ketogenic Diet Improves Seizure Control in Patients with Drug-resistant Epilepsy on the Mixed Fat Ketogenic Diet: A Retrospective Open Label Trial

Introduction

The ketogenic diet (KD) is used for drug-resistant epilepsy. However, some patients find only a modest benefit, which may plateau over time. Evidence from several animal and human studies suggests that polyunsaturated fatty acids (PUFAs) may be a beneficial form of treatment for these patients. This retrospective study was conducted to evaluate whether a switch from classic mixed fats KD (MFKD) to a natural polyunsaturated fatty acid KD (PUFA-KD) would improve seizure control.

Methods

The study evaluated the medical paper record forms of patients who had at least one seizure per week despite the use of MFKD. These patients were started on PUFA-KD and grouped according to the oils preferred. We analyzed the effect on seizure control, tolerability, blood lipids, and adverse effects and whether the type of seizures, age of seizure onset, age at which KD was started, and the ratio of omega 6: omega 3 (n6:n3) fatty acids had any effect on seizure control.

Results

Data from fifty patients (aged 10 months to 35 years) were analyzed. At the end of six and 12 months on the PUFA-KD, 12% (6) and 16% (8) were seizure-free and 82% (41) and 88% (44) had a >50% reduction in seizures, respectively. The mean seizure control at 12 months was highest in patients with mixed seizures followed by those with generalized seizures and lowest for those with focal seizures. Seizure control at 12 months was inversely correlated to the age of onset of epilepsy and age at initiation of KD. This improvement was independent of the type of PUFAs and the ratio of n6:n3 used. The PUFA-KD was generally well tolerated. Blood lipid levels significantly improved.

Conclusion

Changing to PUFA-KD improved seizure control in patients who did not respond satisfactorily to MFKD.

Intravenous immunoglobulins for epilepsy

BACKGROUND

Epilepsy is a common neurological condition, with an estimated incidence of 50 per 100,000 persons. People with epilepsy may present with various types of immunological abnormalities, such as low serum immunoglobulin A (IgA) levels, lack of the immunoglobulin G (IgG) subclass and identification of certain types of antibodies. Intravenous immunoglobulin (IVIg) treatment may represent a valuable approach and its efficacy has important implications for epilepsy management. This is an update of a Cochrane review first published in 2011 and last updated in 2017.

OBJECTIVES

To examine the effects of IVIg on the frequency and duration of seizures, quality of life and adverse effects when used as monotherapy or as add-on treatment for people with epilepsy.

SEARCH METHODS

For the latest update, we searched the Cochrane Register of Studies (CRS Web) (20 December 2018), MEDLINE (Ovid, 1946 to 20 December 2018), Web of Science (1898 to 20 December 2018), ISRCTN registry (20 December 2018), WHO International Clinical Trials Registry Platform (ICTRP, 20 December 2018), the US National Institutes of Health ClinicalTrials.gov (20 December 2018), and reference lists of articles.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials of IVIg as monotherapy or add-on treatment in people with epilepsy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the trials for inclusion and extracted data. We contacted study authors for additional information. Outcomes included percentage of people rendered seizure-free, 50% or greater reduction in seizure frequency, adverse effects, treatment withdrawal and quality of life.

MAIN RESULTS

We included one study (61 participants). The included study was a randomised, double-blind, placebo-controlled, multicentre trial which compared the treatment efficacy of IVIg as an add-on with a placebo add-on in patients with drug-resistant epilepsy. Seizure freedom was not reported in the study. There was no significant difference between IVIg and placebo in 50% or greater reduction in seizure frequency (RR 1.89, 95% CI 0.85 to 4.21; one study, 58 participants; low-certainty evidence). The study reported a statistically significant effect for global assessment in favour of IVIg (RR 3.29, 95% CI 1.13 to 9.57; one study, 60 participants; low-certainty evidence). No adverse effects were demonstrated. We found no randomised controlled trials that investigated the effects of IVIg monotherapy for epilepsy. Overall, the included study was rated at low to unclear risk of bias. Using GRADE methodology, the certainty of the evidence was rated as low.

AUTHORS' CONCLUSIONS

We cannot draw any reliable conclusions regarding the efficacy of IVIg as a treatment for epilepsy. Further randomised controlled trials are needed.

Role of Astrocytes in Post-traumatic Epilepsy

Traumatic brain injury, a common cause of acquired epilepsy, is typical to find necrotic cell death within the injury core. The dynamic changes in astrocytes surrounding the injury core contribute to epileptic seizures associated with intense neuronal firing. However, little is known about the molecular mechanisms that activate astrocytes during traumatic brain injury or the effect of functional changes of astrocytes on seizures. In this comprehensive review, we present our cumulated understanding of the complex neurological affection in astrocytes after traumatic brain injury. We approached the problem through describing the changes of cell morphology, neurotransmitters, biochemistry, and cytokines in astrocytes during post-traumatic epilepsy. In addition, we also discussed the relationship between dynamic changes in astrocytes and seizures and the current pharmacologic agents used for treatment. Hopefully, this review will provide a more detailed knowledge from which better therapeutic strategies can be developed to treat post-traumatic epilepsy.

Ameliorative influence of Cnestis ferruginea vahl ex DC (Connaraceae) root extract on kainic acid-induced temporal lobe epilepsy in mice: Role of oxidative stress and neuroinflammation

ETHNOPHARMACOLOGY RELEVANCE: the root decoction of Cnestis ferruginea Vahl ex DC (Connaraceae) is widely used in traditional African medicine for the treatment of various ailments including pain, inflammation and epilepsy. We have earlier reported anticonvulsant effect of Cnestis ferruginea root extract in mice.

AIM OF THE STUDY

to evaluate the effect of ethanolic root extract of Cnestis ferruginea (CF) on kainic acid (KA)-induced temporal lobe epilepsy (TLE) in mice as well as the involvement of inflammatory mediators and oxidative stress.

MATERIALS AND METHODS

mice were randomly divided into preventive treatment (vehicle (normal saline) or CF (400 mg/kg, p.o.) for 3 consecutive days before KA (5 mg/kg, i.p.) on days 4 and 5. In the reversal model, KA (5 mg/kg, i.p.) was administered on days 1 and 2 before vehicle or CF (400 mg/kg) administration on days 3-5. The effect of treatments on seizure severity was recorded using Racine scale. Animals were euthanized on day 5, 6 h after last KA exposure in preventive model and 1 h after CF administration in reversal model to estimate markers of oxidative stress and neuroinflammation.

RESULTS

exposure of mice to KA induced TLE evidenced in increased severity of seizures which was significantly reduced by the pre- and post-treatment of mice with CF. Moreso, KA-induced malondialdehyde/nitrite generation and GSH deficit in the brain were attenuated by CF treatments. KA-induced up-regulation of inflammatory transcription factors; cyclooxygenase-2 (COX-2) and nuclear facor-kappaB (NF-κB) in the CA1, CA2, CA3 and dentate gyrus (DG) regions of the hippocampus regions were attenuated by CF treatments.

CONCLUSION

findings from this study showed that Cnestis ferruginea root extract ameliorated KA-induced TLE through enhancement of antioxidant defense mechanism and attenuation of neuro-inflammatory transcription factors. Thus, could possibly be a potential phytotherapeutic agent in the management of temporal lobe epilepsy.

Inhibition of human microsomal PGE2 synthase-1 reduces seizure-induced increases of P-glycoprotein expression and activity at the blood-brain barrier

The cause of antiseizure drug (ASD) resistance in epilepsy is poorly understood. Here, we focus on the transporter P-glycoprotein (P-gp) that is partly responsible for limited ASD brain uptake, which is thought to contribute to ASD resistance. We previously demonstrated that cyclooxygenase-2 (COX-2) and the prostaglandin E receptor, prostanoid E receptor subtype 1, are involved in seizure-mediated P-gp up-regulation. Thus, we hypothesized that inhibiting microsomal prostaglandin E₂ (PGE2) synthase-1 (mPGES-1), the enzyme generating PGE2, prevents blood-brain barrier P-gp up-regulation after status epilepticus (SE). To test our hypothesis, we exposed isolated brain capillaries to glutamate ex vivo and used a combined in vivo-ex vivo approach by isolating brain capillaries from humanized mPGES-1 mice to study P-gp levels. We demonstrate that glutamate signaling through the NMDA receptor, cytosolic phospholipase A2, COX-2, and mPGES-1 increases P-gp protein expression and transport activity levels. We show that mPGES-1 is expressed in human, rat, and mouse brain capillaries. We show that BI1029539, an mPGES-1 inhibitor, prevented up-regulation of P-gp expression and transport activity in capillaries exposed to glutamate and in capillaries from humanized mPGES-1 mice after SE. Our data provide key signaling steps underlying seizure-induced P-gp up-regulation and suggest that mPGES-1 inhibitors could potentially prevent P-gp up-regulation in epilepsy.-Soldner, E. L. B., Hartz, A. M. S., Akanuma, S.-I., Pekcec, A., Doods, H., Kryscio, R. J., Hosoya, K.-I., Bauer, B. Inhibition of human microsomal PGE2 synthase-1 reduces seizure-induced increases of P-glycoprotein expression and activity at the blood-brain barrier.

Reactive oxygen species-responsive drug delivery systems for the treatment of neurodegenerative diseases

Neurodegenerative diseases and disorders seriously impact memory and cognition and can become life-threatening. Current medical techniques attempt to combat these detrimental effects mainly through the administration of neuromedicine. However, drug efficacy is limited by rapid dispersal of the drugs to off-target sites while the site of administration is prone to overdose. Many neuropathological conditions are accompanied by excessive reactive oxygen species (ROS) due to the inflammatory response. Accordingly, ROS-responsive drug delivery systems have emerged as a promising solution. To guide intelligent and comprehensive design of ROS-responsive drug delivery systems, this review article discusses the two following topics: (1) the biology of ROS in both healthy and diseased nervous systems and (2) recent developments in ROS-responsive, drug delivery system design. Overall, this review article would assist efforts to make better decisions about designing ROS-responsive, neural drug delivery systems, including the selection of ROS-responsive functional groups.

Respiratory gases, air pollution and epilepsy

A growing number of studies have shown that exposure to air pollutants such as particulate matter and gases can cause cardiovascular, neurodegenerative and psychiatric diseases. The severity of the changes depends on several factors such as exposure time, age and gender. Inflammation has been considered as one of the main factors associated with the generation of these diseases. Here we present some cellular mechanisms activated by air pollution that may represent risk factors for epilepsy and drug resistance associated to epilepsy.

Assessment of genes involved in behavior, learning, memory, and synaptic plasticity following status epilepticus in rats

OBJECTIVE

In this study, it was aimed to evaluate cognitive and behavioral changes after status epilepticus (SE) induced by pentylenetetrazole in immature rats via Morris water maze and open-field area tests and to assess alterations in expression of 84 key genes involved in synaptic plasticity after SE.

METHOD

The study was conducted on 30 immature rats (12-days old). The rats were assigned into groups as control and experiment (SE) groups. The SE was induced by pentylenetetrazole in 12-days old rats. In addition, experiment group was divided into two groups as mature (n = 8) and immature SE (n = 8) subgroups. Again, the control group was divided into two groups as mature (n = 7) and immature control (n = 7) subgroups. Hippocampal tissue samples were prepared, and expression of 84 key genes involved in synaptic plasticity was assessed in Genome and Stem Cell Center of Erciyes University before behavioral tests in immature rats (22-days old) and after open-filed area and Morris water maze tests in mature rats (72-days old) in both experiment and control groups.

RESULTS

No significant difference was detected in behavioral tests assessing spatial memory and learning among groups. Significant differences were detected, ARC (activity-regulated cytoskeleton-associated protein), BDNF (brain-derived neurotrophic factor), MAPK1 (mitogen-activated protein kinase 1), NR4A1 (nuclear receptor subfamily 4 group A member 1), PPP3CA (protein phosphatase 3 catalytic subunit alpha), RGS2 (regulator of G protein signaling 2), and TNF (tumor necrosis factor) gene expressions between control and experiment groups in immature rats whereas in ADCY8 (adenylate cyclase 8), BDNF (brain-derived neurotrophic factor), EGR4 (early growth response 4), and KIF17 (kinesin family member 17) gene expressions between control and experiment groups in mature rats.

DISCUSSION

In this study, differences detected in gene expressions of synaptic plasticity after SE indicate in which steps of synaptic plasticity may be problematic in epileptogenesis. The gene expressions in this study may be considered as potential biomarkers; however, epileptogenesis is a dynamic process and cannot be explained through a single mechanism. Future studies on epileptogenesis and studies specifically designed to evaluate genes detected in our study will further elucidate synaptic plasticity in epilepsy and epileptogenesis.

Galangin Prevents Increased Susceptibility to Pentylenetetrazol-Stimulated Seizures by Prostaglandin E2

Epilepsy is one of the most common chronic neurological diseases. It is characterized by recurrent epileptic seizures, where one-third of patients are refractory to existing treatments. Evidence revealed the association between neuroinflammation and increased susceptibility to seizures since there is a pronounced increase in the expression of key inflammatory mediators, such as prostaglandin E₂ (PGE₂), during seizures. The purpose of this study was to investigate whether PGE₂ increases susceptibility to pentylenetetrazol-induced (PTZ) seizures. Subsequently, we evaluated if the flavonoid isolated from the plant Piper aleyreanum (galangin) presented any anticonvulsive effects. Our results demonstrated that the group treated with PGE₂ increased susceptibility to PTZ and caused myoclonic and generalized seizures, which increased seizure duration and electroencephalographic wave amplitudes. Furthermore, treatment with PGE₂ and PTZ increased IBA-1 (microglial marker), GFAP (astrocytic marker), 4-HNE (lipid peroxidation marker), VCAM-1 (vascular cell adhesion molecule 1), and p-PKAIIα (phosphorylated cAMP-dependent protein kinase) immunocontent. Indeed, galangin prevented behavioral and electroencephalographic seizures, reactive species production, decreased microglial and astrocytic immunocontent, as well as decreased VCAM-1 immunocontent and p-PKA/PKA ratio induced by PGE₂/PTZ. Therefore, this study suggests galangin may have an antagonizing role on PGE₂-induced effects, reducing cerebral inflammation and protecting from excitatory effects evidenced by administrating PGE₂ and PTZ. However, further studies are needed to investigate the clinical implications of the findings and their underlying mechanisms.

2-Deoxyglucose protects hippocampal neurons against kainate-induced temporal lobe epilepsy by modulating monocyte-derived macrophages (mo-MΦ) and progranulin production in the hippocampus

Inflammation is an important factor in the pathology of epilepsy with the hallmarks of resident microglia activation and infiltration of circulating monocytes in the damaged area. In the case of recovery and tissue repair, some monocytes change to macrophages (mo-MΦ) to enhance tissue repair. 2-deoxyglucose (2DG) is an analog of glucose capable of protecting the brain, and progranulin is a neurotrophic factor produced mainly by microglia and has an inflammation modulator effect. This study attempted to evaluate if one of the neuroprotective mechanisms of 2-DG is comprised of increasing monocyte-derived macrophages (mo-MΦ) and progranulin production. Status epilepticus (SE) was induced by i.c.v. injection of kainic acid (KA).2DG (125/mg/kg/day) was administered intraperitoneally. Four days later, animals were sacrificed. Their brain sections were then stained with Cresyl violet and Fluoro-Jade B to count the number of necrotic and degenerating neurons in CA3 and Hilus of dentate gyrus of the hippocampus. Lastly, immunohistochemistry was used to detect CD11b + monocyte, macrophage cells, and Progranulin level was evaluated by Western blotting. The histological analysis showed that 2DG can reduce the number of necrotic and degenerating neurons in CA3 and Hilar areas. Following KA administration, a great number of cD11b⁺ cells with monocyte morphology were observed in the hippocampus. 2DG not only reduced cD11b⁺ monocyte cells but was able to convert them to cells with the morphology of macrophages (mo-MΦ). 2DG also caused a significant increase in progranulin level in the hippocampus. Because macrophages and microglia are the most important sources of progranulin, it appears that 2DG caused the derivation of monocytes to macrophages and these cells produced progranulin with a subsequent anti-inflammation effect. In summary, it was concluded that 2DG is neuroprotective and probably one of its neuroprotective mechanisms is by modulating monocyte-derived macrophages by progranulin production.