The role of inflammation in epileptogenesis

Seizures in the context of occult cerebrovascular disease

There is an important bidirectional relationship between seizures and cerebrovascular disease (CVD). Aside from poststroke epilepsy, Occult CVD is an important cause of late-onset seizures (LOS) and late-onset epilepsy (LOE). Late-onset seizures/LOE are associated with a threefold increased risk of subsequent clinical stroke. This relationship exists not only in later life, but with 'late-onset' seizures or epilepsy occurring from the fourth decade of life onwards. There is increasing evidence for the importance of hypertension and cerebral small vessel disease (SVD) in epileptogenesis, but there is a considerable need for further work to elucidate underlying mechanisms. There may be a disproportionately increased risk of intracerebral hemorrhage (ICH) after LOS/LOE; this too requires further study. There is also a bidirectional relationship between LOS/LOE and cognitive impairment/dementia: it is likely that there are important interactions between vascular and neurodegenerative pathological processes mediating LOE, stroke, and dementia. There is a pressing need for better epidemiological and natural history data as well as elucidation of epileptogenic mechanisms, in order to progress our understanding and to better inform clinical practice.

Mouse Models of Familial Hemiplegic Migraine for Studying Migraine Pathophysiology

Migraine, an extremely disabling neurological disorder, has a strong genetic component. Since monogenic mi-graines (resulting from mutations or changes in a single gene) may help researchers discover migraine pathophysiology, transgenic mice models harboring gene mutations identified in Familial Hemiplegic Migraine (FHM) patients have been gen-erated. Studies in these FHM mutant mice models have shed light on the mechanisms of migraine and may aid in the identifi-cation of novel targets for treatment. More specifically, the studies shed light on how gene mutations, hormones, and other factors impact the pathophysiology of migraine. The models may also be of relevance to researchers outside the field of mi-graine as some of their aspects are relevant to pain in general. Additionally, because of the comorbidities associated with mi-graine, they share similarities with the mutant mouse models of epilepsy, stroke, and perhaps depression. Here, we review the experimental data obtained from these mutant mice and focus on how they can be used to investigate the pathophysiology of migraine, including synaptic plasticity, neuroinflammation, metabolite alterations, and molecular and behavioral mecha-nisms of pain.

Potent, Selective, Water Soluble, Brain-Permeable EP2 Receptor Antagonist for Use in Central Nervous System Disease Models

Activation of prostanoid EP2 receptor exacerbates neuroinflammatory and neurodegenerative pathology in central nervous system diseases such as epilepsy, Alzheimer's disease, and cerebral aneurysms. A selective and brain-permeable EP2 antagonist will be useful to attenuate the inflammatory consequences of EP2 activation and to reduce the severity of these chronic diseases. We recently developed a brain-permeable EP2 antagonist 1 (TG6-10-1), which displayed anti-inflammatory and neuroprotective actions in rodent models of status epilepticus. However, this compound exhibited moderate selectivity to EP2, a short plasma half-life in rodents (1.7 h) and low aqueous solubility (27 μM), limiting its use in animal models of chronic disease. With lead-optimization studies, we have developed several novel EP2 antagonists with improved water solubility, brain penetration, high EP2 potency, and selectivity. These novel inhibitors suppress inflammatory gene expression induced by EP2 receptor activation in a microglial cell line, reinforcing the use of EP2 antagonists as anti-inflammatory agents.

MicroRNA Regulatory Network as Biomarkers of Late Seizure in Patients with Spontaneous Intracerebral Hemorrhage

Approximately 15% of patients experience seizures after spontaneous intracerebral hemorrhage (ICH). The pathogenesis of seizures post-ICH is not well-known; however, iron deposition-related neuronal injury following hemoglobin breakdown may contribute. Profiling known miRNAs to identify biomarkers for post-ICH late seizures, we found 64 differentially expressed miRNA: 32 upregulated and 32 downregulated in seizure vs. non-seizure. Functional classification of upregulated miRNA for KEGG pathways and biological processes identified enrichment for cell cycle, protein modifications, and FoxO neurotrophin signaling pathways. No significant enrichment was found for downregulated miRNA. Molecular functions Gene Ontology (GO) terms enriched for upregulated miRNA are numerous, while downregulated miRNAs were associated with ion channel activity. RT-PCR confirmed two miRNAs, 4317 and 4325, were differentially expressed in patients who developed seizures at 1 year. MiR-4317 regulates SLC38A1, a glutamine-glutamate transporter. Integrated miRNA-mRNA network analysis identified COMMD6, APOBEC2, and RASSF6-involved in NF-kB regulation. Two miRNAs (miR-4317 and 4325) differentiated post-ICH late seizures vs. non-seizures at 1 year. The results suggest functional and miRNA-mRNA networks as potential biomarkers for post-ICH late seizures.

The Role of NLRP3 and IL-1β in Refractory Epilepsy Brain Injury

Objective: The objective of this study was to investigate the roles and mechanisms of inflammatory mediators NLRP3 and IL-1β in refractory temporal epilepsy brain injury.

Method: First, the brain tissue and the peripheral blood of children undergoing intractable temporal lobe epilepsy surgery were analyzed as research objects. The expression levels of NLRP3 in brain tissue and IL-1β in blood were measured. A model of temporal lobe epilepsy was established using wild-type and NLRP3 knockout 129 mice. Pilocarpine was injected intraperitoneally into the experimental group, and isovolumetric saline was injected intraperitoneally into the control group (n = 8 in each group). The expression of IL-1β in the peripheral blood, cerebral cortex, and hippocampus of mice was measured by ELISA at 3 h, 24 h, 3 days, and 7 days after modeling. Fluoro-Jade B (FJB) and TUNEL methods were used to determine necrosis and apoptosis in hippocampal neurons, respectively, and the expression of NLRP3 in the cortex was measured by immunofluorescence methods.

Result: (1) The IL-1β levels in the peripheral blood of children with intractable temporal lobe epilepsy were higher than those in the control group (t = 2.813, P = 0.01). There was also a positive correlation between IL-1β expression levels and the onset time of a single convulsion in patients with refractory epilepsy (r = 0.9735, P < 0.05). The expression level of NLRP3 in the cerebral cortex of patients with refractory temporal lobe epilepsy was higher than that in the control group. (2) The expression level of NLRP3 in the hippocampus of wild-type mice increased 3 days after modeling and decreased slightly at 7 days but remained higher than that of the control group. IL-1β levels in peripheral blood were significantly higher than those in the control group at 3 days (t = 8.259, P < 0.0001). The IL-1β levels in the peripheral blood of NLRP3 knockout mice were lower than those in the wild-type group at 3 days (t = 3.481, P = 0.004). At day 7, the neuronal necrosis and apoptosis levels in the CA3 region of the hippocampus decreased.

Conclusion: NLRP3 may be involved in the development of refractory temporal lobe epilepsy. Inhibiting NLRP3 may alleviate local brain injury by downregulating the IL-1β expression. The IL-1β levels in the peripheral blood of patients with refractory temporal lobe epilepsy may reflect the severity of convulsions.

Vascular Integrity and Signaling Determining Brain Development, Network Excitability, and Epileptogenesis

Our understanding of the etiological mechanisms leading up to epilepsy has undergone radical changes over time due to more insights into the complexity of the disease. The traditional hypothesis emphasized network hyperexcitability and an imbalance of inhibition and excitation, eventually leading to seizures. In this context, the contribution of the vascular system, and particularly the interactions between blood vessels and neuronal tissue, came into focus only recently. Thus, one highly exciting causative or contributing factor of epileptogenesis is the disruption of the blood-brain barrier (BBB) in the context of not only posttraumatic epilepsy, but also other etiologies. This hypothesis is now recognized as a synergistic mechanism that can give rise to epilepsy, and BBB repair for restoration of cerebrovascular integrity is considered a therapeutic alternative. Endothelial cells lining the inner surface of blood vessels are an integral component of the BBB system. Sealed by tight junctions, they are crucial in maintaining homeostatic activities of the brain, as well as acting as an interface in the neurovascular unit. Additional potential vascular mechanisms such as inflammation, altered neurovascular coupling, or changes in blood flow that can modulate neuronal circuit activity have been implicated in epilepsy. Our own work has shown how intrinsic defects within endothelial cells from the earliest developmental time points, which preclude neuronal changes, can lead to vascular abnormalities and autonomously support the development of hyperexcitability and epileptiform activity. In this article, we review the importance of vascular integrity and signaling for network excitability and epilepsy by highlighting complementary basic and clinical research studies and by outlining possible novel therapeutic strategies.

Molecular alterations of the TLR4-signaling cascade in canine epilepsy

BACKGROUND

Cumulating evidence from rodent models points to a pathophysiological role of inflammatory signaling in the epileptic brain with Toll-like receptor-4 signaling acting as one key factor. However, there is an apparent lack of information about expression alterations affecting this pathway in canine patients with epilepsy. Therefore, we have analyzed the expression pattern of Toll-like receptor 4 and its ligands in brain tissue of canine patients with structural or idiopathic epilepsy in comparison with tissue from laboratory dogs or from owner-kept dogs without neurological diseases.

RESULTS

The analysis revealed an overexpression of Toll-like receptor-4 in the CA3 region of dogs with structural epilepsy. Further analysis provided evidence for an upregulation of Toll-like receptor-4 ligands with high mobility group box-1 exhibiting increased expression levels in the CA1 region of dogs with idiopathic and structural epilepsy, and heat shock protein 70 exhibiting increased expression levels in the piriform lobe of dogs with idiopathic epilepsy. In further brain regions, receptor and ligand expression rates proved to be either in the control range or reduced below control levels.

CONCLUSIONS

Our study reveals complex molecular alterations affecting the Toll-like receptor signaling cascade, which differ between epilepsy types and between brain regions. Taken together, the data indicate that multi-targeting approaches modulating Toll-like receptor-4 signaling might be of interest for management of canine epilepsy. Further studies are recommended to explore respective molecular alterations in more detail in dogs with different etiologies and to confirm the role of the pro-inflammatory signaling cascade as a putative target.

Structural, Molecular, and Functional Alterations of the Blood-Brain Barrier during Epileptogenesis and Epilepsy: A Cause, Consequence, or Both?

The blood-brain barrier (BBB) is a dynamic, highly selective barrier primarily formed by endothelial cells connected by tight junctions that separate the circulating blood from the brain extracellular fluid. The endothelial cells lining the brain microvessels are under the inductive influence of neighboring cell types, including astrocytes and pericytes. In addition to the anatomical characteristics of the BBB, various specific transport systems, enzymes and receptors regulate molecular and cellular traffic across the BBB. While the intact BBB prevents many macromolecules and immune cells from entering the brain, following epileptogenic brain insults the BBB changes its properties. Among BBB alterations, albumin extravasation and diapedesis of leucocytes from blood into brain parenchyma occur, inducing or contributing to epileptogenesis. Furthermore, seizures themselves may modulate BBB functions, permitting albumin extravasation, leading to activation of astrocytes and the innate immune system, and eventually modifications of neuronal networks. BBB alterations following seizures are not necessarily associated with enhanced drug penetration into the brain. Increased expression of multidrug efflux transporters such as P-glycoprotein likely act as a 'second line defense' mechanism to protect the brain from toxins. A better understanding of the complex alterations in BBB structure and function following seizures and in epilepsy may lead to novel therapeutic interventions allowing the prevention and treatment of epilepsy as well as other detrimental neuro-psychiatric sequelae of brain injury.

Divergent metabolic substrate utilization in brain during epileptogenesis precedes chronic hypometabolism

Alterations in metabolism during epileptogenesis may be a therapy target. Recently, an increase in amino acid transport into the brain was proposed to play a role in epileptogenesis. We aimed to characterize alterations of substrate utilization during epileptogenesis and in chronic epilepsy. The lithium-pilocarpine post status epilepticus (SE) rat model was used. We performed longitudinal O-(2-[(18)F]fluoroethyl)-l-tyrosine (18F-FET) and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and calculated 18F-FET volume of distribution (Vt) and 18F-FDG uptake. Correlation analyses were performed with translocator protein-PET defined neuroinflammation from previously acquired data. We found reduced 18F-FET Vt at 48 h after SE (amygdala: -30.2%, p = 0.014), whereas 18F-FDG showed increased glucose uptake 4 and 24 h after SE (hippocampus: + 43.6% and +42.5%, respectively; p < 0.001) returning to baseline levels thereafter. In chronic epileptic animals, we found a reduction in 18F-FET and 18F-FDG in the hippocampus. No correlation was found for 18F-FET or 18F-FDG to microglial activation at seven days post SE. Whereas metabolic alterations do not reflect higher metabolism associated to activated microglia, they might be partially driven by chronic neuronal loss. However, both metabolisms diverge during early epileptogenesis, pointing to amino acid turnover as a possible biomarker and/or therapeutic target for epileptogenesis.

Pavlovian Conditioning of Immunological and Neuroendocrine Functions

The phenomenon of behaviorally conditioned immunological and neuroendocrine functions has been investigated for the past 100 yr. The observation that associative learning processes can modify peripheral immune functions was first reported and investigated by Ivan Petrovic Pavlov and his co-workers. Their work later fell into oblivion, also because so little was known about the immune system’s function and even less about the underlying mechanisms of how learning, a central nervous system activity, could affect peripheral immune responses. With the employment of a taste-avoidance paradigm in rats, this phenomenon was rediscovered 45 yr ago as one of the most fascinating examples of the reciprocal functional interaction between behavior, the brain, and peripheral immune functions, and it established psychoneuroimmunology as a new research field. Relying on growing knowledge about efferent and afferent communication pathways between the brain, neuroendocrine system, primary and secondary immune organs, and immunocompetent cells, experimental animal studies demonstrate that cellular and humoral immune and neuroendocrine functions can be modulated via associative learning protocols. These (from the classical perspective) learned immune responses are clinically relevant, since they affect the development and progression of immune-related diseases and, more importantly, are also inducible in humans. The increased knowledge about the neuropsychological machinery steering learning and memory processes together with recent insight into the mechanisms mediating placebo responses provide fascinating perspectives to exploit these learned immune and neuroendocrine responses as supportive therapies, the aim being to reduce the amount of medication required, diminishing unwanted drug side effects while maximizing the therapeutic effect for the patient’s benefit.

Epilepsy and Alterations of the Blood-Brain Barrier: Cause or Consequence of Epileptic Seizures or Both?

The blood-brain barrier (BBB) is a dynamic, highly selective barrier primarily formed by endothelial cells connected by tight junctions that separate the circulating blood from the brain extracellular fluid, thereby preserving a narrow and stable homeostatic control of the neuronal environment. The endothelial cells lining the brain microvessels are under the inductive influence of neighboring cell types within the "neurovascular unit" including astrocytes and pericytes. In addition to the morphological characteristics of the BBB, various specific transport systems, enzymes, and receptors regulate the molecular and cellular traffic across the barrier. Furthermore, the intact BBB prevents many macromolecules and immune cells from entering the brain. This changes dramatically following epileptogenic brain insults; such insults, among other BBB alterations, lead to albumin extravasation and diapedesis of leukocytes from blood into brain parenchyma, inducing or contributing to epileptogenesis, which finally leads to development of spontaneous recurrent seizures and epilepsy. Furthermore, seizures themselves may cause BBB disruption with albumin extravasation, which has been shown to be associated with activation of astrocytes, activation of innate immune systems, and modifications of neuronal networks. However, seizure-induced BBB disruption is not necessarily associated with enhanced drug penetration into the brain, because the BBB expression of multidrug efflux transporters such as P-glycoprotein increases, most likely as a "second line defense" mechanism to protect the brain from drug toxicity. Hopefully, a better understanding of the complex BBB alterations in response to seizures and epilepsy can lead to novel therapeutic intervention to prevent epileptogenesis and the development of other detrimental sequelae of brain injury.

A systems approach identifies Enhancer of Zeste Homolog 2 (EZH2) as a protective factor in epilepsy

Complex neurological conditions can give rise to large scale transcriptomic changes that drive disease progression. It is likely that alterations in one or a few transcription factors or cofactors underlie these transcriptomic alterations. Identifying the driving transcription factors/cofactors is a non-trivial problem and a limiting step in the understanding of neurological disorders. Epilepsy has a prevalence of 1% and is the fourth most common neurological disorder. While a number of anti-seizure drugs exist to treat seizures symptomatically, none is curative or preventive. This reflects a lack of understanding of disease progression. We used a novel systems approach to mine transcriptome profiles of rodent and human epileptic brain samples to identify regulators of transcriptional networks in the epileptic brain. We find that Enhancer of Zeste Homolog 2 (EZH2) regulates differentially expressed genes in epilepsy across multiple rodent models of acquired epilepsy. EZH2 undergoes a prolonged upregulation in the epileptic brain. A transient inhibition of EZH2 immediately after status epilepticus (SE) robustly increases spontaneous seizure burden weeks later. This suggests that EZH2 upregulation is a protective. These findings are the first to characterize a role for EZH2 in opposing epileptogenesis and debut a bioinformatic approach to identify nuclear drivers of complex transcriptional changes in disease.

Loss of presenilin 2 age-dependently alters susceptibility to acute seizures and kindling acquisition

Patients with Alzheimer's disease (AD) experience seizures at higher rates than the general population of that age, suggesting an underexplored role of hyperexcitability in AD. Genetic variants in presenilin (PSEN) 1 and 2 genes lead to autosomal dominant early-onset AD (ADAD); patients with PSEN gene variants also report seizures. Pharmacological control of seizures in AD may be disease-modifying. Preclinical efficacy of FDA-approved antiseizure drugs (ASDs) is well defined in young adult rodents; however, the efficacy of ASDs in aged rodents with chronic seizures is less clear. The mechanism by which ADAD genes lead to AD remains unclear, and even less studied is the pathogenesis of epilepsy in AD. PSEN variants generally all result in a biochemical loss of function (De Strooper, 2007). We herein determined whether well-established models of acute and chronic seizure could be used to explore the relationship between AD genes and seizures through investigating whether loss of normal PSEN2 function age-dependently influenced susceptibility to seizures and/or corneal kindling acquisition. PSEN2 knockout (KO) and age-matched wild-type (WT) mice were screened from 2- to 10-months-old to establish age-dependent focal seizure threshold. Additionally, PSEN2 KO and WT mice aged 2- and 8-months-old underwent corneal kindling such that mice were aged 3- and 9-months old at the beginning of ASD efficacy testing. We then defined the dose-dependent efficacy of mechanistically distinct ASDs on kindled seizures of young versus aged mice to better understand the applicability of corneal kindling to real-world use for geriatric patients. PSEN2 KO mice demonstrated early-life reductions in seizure threshold. However, kindling acquisition was delayed in 2-month-old PSEN2 KO versus WT mice. Young male WT mice took 24.3 ± 1.3 (S.E.M.) stimulations to achieve kindling criterion, whereas age-matched PSEN2 KO male mice took 41.2 ± 1.1 stimulations (p < .0001). The rate of kindling acquisition of 8-month-old mice was no longer different from WT. This study demonstrates that loss of normal PSEN2 function is associated with age-dependent changes in the in vivo susceptibility to acute seizures and kindling. Loss of normal PSEN2 function may be an underexplored molecular contributor to seizures. The use of validated models of chronic seizures in aged rodents may uncover age-related changes in susceptibility to epileptogenesis and/or ASD efficacy in mice with AD-associated genotypes, which may benefit the management of seizures in AD.

Inflammation and reactive oxygen species in status epilepticus: Biomarkers and implications for therapy

Preclinical studies in immature and adult rodents and clinical observations show that neuroinflammation and oxidative stress are rapid onset phenomena occurring in the brain during status epilepticus and persisting thereafter. Notably, both neuroinflammation and oxidative stress contribute to the acute and long-term sequelae of status epilepticus thus representing potential druggable targets. Antiinflammatory drugs that interfere with the IL-1β pathway, such as anakinra, can control benzodiazepine-refractory status epilepticus in animals, and there is recent proof-of-concept evidence for therapeutic effects in children with Febrile infection related epilepsy syndrome (FIRES). Inhibitors of monoacylglycerol lipase and P2X7 receptor antagonists are also promising antiinflammatory drug candidates for rapidly aborting de novo status epilepticus and provide neuroprotection. Antiinflammatory and antioxidant drugs administered to rodents during status epilepticus and transiently thereafter, prevent long-term sequelae such as cognitive deficits and seizure progression in animals developing epilepsy. Some drugs are already in medical use and are well-tolerated, therefore, they may be considered for treating status epilepticus and its neurological consequences. Finally, markers of neuroinflammation and oxidative stress are measureable in peripheral blood and by neuroimaging, which offers an opportunity for developing prognostic and predictive mechanistic biomarkers in people exposed to status epilepticus. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures.

Early treatment with C1 esterase inhibitor improves weight but not memory deficits in a rat model of status epilepticus

BACKGROUND

Status epilepticus (SE) is a prolonged and continuous seizure that lasts for at least 5 min. An episode of SE in a healthy system can lead to the development of spontaneous seizures and cognitive deficits which may be accompanied by hippocampal injury and microgliosis. Although the direct mechanisms underlying the SE-induced pathophysiology remain unknown, a candidate mechanism is hyperactivation of the classical complement pathway (C1q-C3 signaling). We recently reported that SE triggered an increase in C1q-C3 signaling in the hippocampus that closely paralleled cognitive decline. Thus, we hypothesized that blocking activation of the classical complement pathway immediately after SE may prevent the development of SE-induced hippocampal-dependent learning and memory deficits.

METHODS

Because C1 esterase inhibitor (C1-INH) negatively regulates activation of the classical complement pathway, we used this drug to test our hypothesis. Two groups of male rats were subjected to 1 hr of SE with pilocarpine (280-300 mg/kg, i.p.), and treated with either C1-INH (SE+C1-INH, 20 U/kg, s.c.) or vehicle (SE+veh) at 4, 24, and 48 h after SE. Control rats were treated with saline. Body weight was recorded for up to 23 days after SE. At two weeks post SE, recognition and spatial memory were determined using Novel Object Recognition (NOR) and Barnes maze (BM), respectively, as well as locomotion and anxiety-like behaviors using Open Field (OF). Histological and biochemical methods were used to measure hippocampal injury including cell death, microgliosis, and inflammation.

RESULTS

One day after SE, both SE groups had a significant loss of body weight compared to controls (p<0.05). By day 14, the weight of SE+C1-INH rats was significantly higher than SE+veh rats (p<0.05), and was not different from controls (p>0.05). At 14 days post-SE, SE+C1-INH rats displayed higher mobility (distance travelled and average speed, p<0.05) and had reduced anxiety-like behaviors (outer duration, p<0.05) than control or SE+veh rats. In NOR, control rats spent significantly more time exploring the novel object vs. the familiar (p<0.05), while rats in both SE groups spent similar amount of time exploring both objects. During days 1-4 of BM training, the escape latency of the control group significantly decreased over time (p<0.05), whereas that of the SE groups did not improve (p>0.05). Compared to vehicle-treated SE rats, SE+C1-INH rats had increased levels of C3 and microglia in the hippocampus, but lower levels of caspase-3 and synaptic markers.

CONCLUSIONS

These findings suggest that acute treatment with C1-INH after SE may have some protective, albeit limited, effects on the physiological recovery of rats' weight and some anxiolytic effects, but does not attenuate SE-induced deficits in hippocampal-dependent learning and memory. Reduced levels of caspase-3 suggest that treatment with C1-INH may protect against cell death, perhaps by regulating inflammatory pathways and promoting phagocytic/clearance pathways.

A preliminary study of the effects of cannabidiol (CBD) on brain structure in patients with epilepsy

Cannabis use is associated with changes in brain structure and function; its neurotoxic effects are largely attributed to Δ⁹-tetrahydrocannabidiol. Whether such effects are present in patients with epilepsy exposed to a highly-purified cannabidiol isolate (CBD; Epidiolex®; Greenwich Biosciences, Inc.) has not been investigated to date. This preliminary study examines whether daily CBD dose of 15-25 mg/kg produces cerebral macrostructure changes and, if present, how they relate to changes in seizure frequency. Twenty-seven patients with treatment-resistant epilepsy were recruited from the University of Alabama at Birmingham CBD Program. Participants provided seizure frequency diaries (SF), completed the Chalfont Seizure Severity Scale (CSSS) and Adverse Events Profile (AEP), and underwent MRI before CBD (baseline) and after achieving a stable CBD dosage (on-CBD). We examined T1-weighted structural images for gray matter volume (GMV) and cortical thickness changes from baseline to on-CBD in 18 participants. Repeated measures t-tests confirmed decreases in SF [t(17) = 3.08, p = 0.0069], CSSS [t(17) = 5.77, p < 0.001], and AEP [t(17) = 3.04, p = 0.0074] between the two time-points. Voxel-level paired samples t-tests did not identify significant changes in GMV or cortical thickness between these two time-points. In conclusion, short-term exposure to highly purified CBD may not affect cortical macrostructure.

Early changes in pro-inflammatory cytokine levels in neonates with encephalopathy are associated with remote epilepsy

BACKGROUND

Neonatal seizures are associated with adverse neurologic sequelae including epilepsy in childhood. Here we aim to determine whether levels of cytokines in neonates with brain injury are associated with acute symptomatic seizures or remote epilepsy.

METHODS

This is a cohort study of term newborns with encephalopathy at UCSF between 10/1993 and 1/2000 who had dried blood spots. Maternal, perinatal/postnatal, neuroimaging, and epilepsy variables were abstracted by chart review. Logistic regression was used to compare levels of cytokines with acute seizures and the development of epilepsy.

RESULTS

In a cohort of 26 newborns with neonatal encephalopathy at risk for hypoxic ischemic encephalopathy with blood spots for analysis, diffuse alterations in both pro- and anti-inflammatory cytokine levels were observed between those with (11/28, 39%) and without acute symptomatic seizures. Seventeen of the 26 (63%) patients had >2 years of follow-up and 4/17 (24%) developed epilepsy. Higher levels of pro-inflammatory cytokines IL-6 and TNF-α within the IL-1β pathway were significantly associated with epilepsy.

CONCLUSIONS

Elevations in pro-inflammatory cytokines in the IL-1β pathway were associated with later onset of epilepsy. Larger cohort studies are needed to confirm the predictive value of these circulating biomarkers.

How do we choose the appropriate animal model for antiseizure therapy development?

Introduction: Epilepsy affects over 65 million people worldwide, and despite the numerous therapies that are currently available for the symptomatic management of chronic seizures, a substantial proportion of the population has not achieved adequate seizure control. Developing more effective and better-tolerated therapies will benefit patients worldwide. Areas covered: This article will discuss the relevant preclinical models that have been instrumental to the development of over 20 antiseizure drugs (ASDs) currently on the market today. While there have been meaningful therapies already developed over the last several decades, this article will highlight remaining areas of unmet medical need. Innovative models of pharmacoresistant epilepsy may advance therapies for patients who currently do not attain sufficient seizure control in the absence of adverse effects. There also remains a need to identify improved therapies for special patient populations, including the very young and old. Expert opinion: ASD development will still find utility in the established models that have been instrumental to the identification of impactful therapies. However, there should now be greater emphasis to implement those models in young and aged rodents to advance novel therapies for patients who are still in need of better tolerated or more effective therapies, such as pediatric and elderly patients.

Ex vivo characterization of neuroinflammatory and neuroreceptor changes during epileptogenesis using candidate positron emission tomography biomarkers

OBJECTIVE

Identification of patients at risk of developing epilepsy before the first spontaneous seizure may promote the development of preventive treatment providing opportunity to stop or slow down the disease.

METHODS

As development of novel radiotracers and on-site setup of existing radiotracers is highly time-consuming and expensive, we used dual-centre in vitro autoradiography as an approach to characterize the potential of innovative radiotracers in the context of epilepsy development. Using brain slices from the same group of rats, we aimed to characterise the evolution of neuroinflammation and expression of inhibitory and excitatory neuroreceptors during epileptogenesis using translational positron emission tomography (PET) tracers; ¹⁸ F-flumazenil (¹⁸ F-FMZ; GABA_A receptor), ¹⁸ F-FPEB (metabotropic glutamate receptor 5; mGluR5), ¹⁸ F-flutriciclamide (translocator protein; TSPO, microglia activation) and ¹⁸ F-deprenyl (monoamine oxidase B, astroglia activation). Autoradiography images from selected time points after pilocarpine-induced status epilepticus (SE; baseline, 24 and 48 hours, 5, 10 and 15 days and 6 and 12-14 weeks after SE) were normalized to a calibration curve, co-registered to an MRI-based 2D region-of-interest atlas, and activity concentration (Bq/mm² ) was calculated.

RESULTS

In epileptogenesis-associated brain regions, ¹⁸ F-FMZ and ¹⁸ F-FPEB showed an early decrease after SE. ¹⁸ F-FMZ decrease was maintained in the latent phase and further reduced in the chronic epileptic animals, while ¹⁸ F-FPEB signal recovered from day 10, reaching baseline levels in chronic epilepsy. ¹⁸ F-flutriciclamide showed an increase of activated microglia at 24 hours after SE, peaking at 5-15 days and decreasing during the chronic phase. On the other hand, ¹⁸ F-deprenyl autoradiography showed late astrogliosis, peaking in the chronic phase.

SIGNIFICANCE

Autoradiography revealed different evolution of the selected targets during epileptogenesis. Our results suggest an advantage of combined imaging of inter-related targets like glutamate and GABA_A receptors, or microglia and astrocyte activation, in order to identify important interactions, especially when using PET imaging for the evaluation of novel treatments.

Repeated Intraperitoneal Administration of Low-Concentration Methylcellulose Leads to Systemic Histologic Lesions Without Loss of Preclinical Phenotype

Methylcellulose (MC; 0.5% concentration) is commonly used when evaluating investigational agents for efficacy in preclinical models of disease. When administered by the oral (PO) route, MC is considered a Food and Drug Administration "generally recognized as safe" compound. Yet, there is limited data pertaining to the tolerability and impact on model fidelity of repeated intraperitoneal administration of 0.5% MC. Chronic administration of high-concentration MC (2%-2.5%) has been used to induce anemia, splenomegaly, and lesions in multiple organ systems in several preclinical species. Histopathological findings from a diagnostic pathologic analysis of a single mouse from our laboratory with experimentally induced chronic seizures that had received repeated intraperitoneal administration of antiseizure drugs delivered in MC revealed similar widespread lesions. This study thus tested the hypothesis that chronic administration of intraperitoneal, but not PO, MC incites histologic lesions without effects on preclinical phenotype. Male CF-1 mice (n = 2-14/group) were randomized to receive either 6 weeks of twice weekly 0.5% MC or saline (intraperitoneal or PO) following induction of chronic seizures. Histology of a subset of mice revealed lesions in kidney, liver, mediastinal lymph nodes, mesentery, aorta, and choroid plexus only in intraperitoneal MC-treated mice (n = 7/7). Kindled mice that received MC PO (n = 5) or saline (intraperitoneal n = 6, PO n = 3) had no lesions. There were no effects of intraperitoneal MC treatment on body weight, appearance, seizure stability, or behavior. Nonetheless, our findings suggest that repeated intraperitoneal, but not PO, MC elicits systemic organ damage without impacting the model phenotype, which may confound interpretation of investigational drug-induced histologic lesions. SIGNIFICANCE STATEMENT: Methylcellulose (0.5% concentration) is commonly used when evaluating investigational agents for efficacy in preclinical models of disease. Herein, we demonstrate that repeated administration of 0.5% methylcellulose by the intraperitoneal, but not oral, route results in systemic inflammation and presence of foam-laden macrophages but does not impact the behavioral phenotype of a rodent model of neurological disease.

Anti-inflammatory treatment with a soluble epoxide hydrolase inhibitor attenuates seizures and epilepsy-associated depression in the LiCl-pilocarpine post-status epilepticus rat model

PURPOSE

This study aimed to investigate whether 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU), a soluble epoxide hydrolase inhibitor with anti-inflammatory effects, could alleviate spontaneous recurrent seizures (SRS) and epilepsy-associated depressive behaviours in the lithium chloride (LiCl)-pilocarpine-induced post-status epilepticus (SE) rat model.

METHODS

The rats were intraperitoneally (IP) injected with LiCl (127 mg/kg) and pilocarpine (40 mg/kg) to induce SE. A video surveillance system was used to monitor SRS in the post-SE model for 6 weeks (from the onset of the 2nd week to the end of the 7th week after SE induction). TPPU (0.1 mg/kg/d) was intragastrically given for 4 weeks from the 21st day after SE induction in the SRS + 0.1 TPPU group. The SRS + PEG 400 group was given the vehicle (40% polyethylene glycol 400) instead, and the control group was given LiCl and PEG 400 but not pilocarpine. The sucrose preference test (SPT) and forced swim test (FST) were conducted to evaluate the depression-like behaviours of rats. Immunofluorescent staining, enzyme-linked immunosorbent assay, and western blot analysis were performed to measure astrocytic and microglial gliosis, neuronal loss, and levels of soluble epoxide hydrolase (sEH), cytokines [tumour necrosis factor alpha (TNF-α), interleukin (IL)-1β, and IL-6], and cyclic adenosine monophosphate (cAMP)-response element binding protein (CREB).

RESULTS

The frequency of SRS was significantly decreased at 6 weeks and 7 weeks after SE induction in the 0.1TPP U group compared with the SRS + PEG 400 group. The immobility time (IMT) evaluated by FST was significantly decreased, whereas the climbing time (CMT) was increased, and the sucrose preference rate (SPR) evaluated by SPT was in an increasing trend. The levels of sEH, TNF-α, IL-1β, and IL-6 in the hippocampus (Hip) and prefrontal cortex (PFC) were all significantly increased in the SRS + PEG 400 group compared with the control group; neuronal loss, astrogliosis, and microglial activation were also observed. The astrocytic and microglial activation and levels of the pro-inflammatory cytokines in the Hip and PFC were significantly attenuated in the TPPU group compared with the SRS + PEG 400 group; moreover, neuronal loss and the decreased CREB expression were significantly alleviated as well.

CONCLUSION

TPPU treatment after SE attenuates SRS and epilepsy-associated depressive behaviours in the LiCl-pilocarpine induced post-SE rat model, and it also exerts anti-inflammatory effects in the brain. Our findings suggest a new therapeutic approach for epilepsy and its comorbidities, especially depression.

Long-term Outcome of Intravenous Lidocaine in Pediatric Cluster Seizures: A Preliminary Study

BACKGROUND

Cluster seizures are life-threatening conditions. They may easily evolve into status epilepticus and are reported in up to 20% to 30% of patients with epilepsy. Sometimes cluster seizures become drug resistant, leading to the use of unconventional therapies. One of these unconventional approaches may be the use of lidocaine, which is a sodium-channel-blocking drug mostly known as a local anesthetic and antiarrhythmic agent.

METHODS

We describe the outcome of four children who were treated with continuous intravenous infusion of 2% lidocaine due to drug-resistant focal cluster seizures. Lidocaine was administered as an initial dose of 1 mg/kg/hour and, subsequently, was increased to 2 to 4 mg/kg/hour. The therapy was continued for five to 10 days. Patients remained under careful cardiological surveillance during the treatment.

RESULTS

Complete seizure remission was achieved in all four children. None of the patients experienced adverse events. Although seizures recurred in all patients within an average time of 2.4 months, they appeared with reduced frequency, and within the follow-up period (mean 7.5 months) no additional cluster seizures occurred.

CONCLUSIONS

Treatment with lidocaine in pediatric cluster seizures may be useful and may be considered as a therapeutic option. Our patients encountered no side effects and experienced prolonged seizure remission, possibly resulting from the effect of lidocaine on sodium channels or from its anti-inflammatory properties. However, more studies are required to confirm the safety and long-term effectiveness of this approach. Clinicians should be aware of possible adverse effects and necessity of sustained cardiological surveillance during the treatment.

Expression of MicroRNAs miR-145, miR-181c, miR-199a and miR-1183 in the Blood and Hippocampus of Patients with Mesial Temporal Lobe Epilepsy

The aim of this study was to analyze the expression profiles of the microRNAs (miRNAs) miR-145, miR-181c, miR-199a and miR-1183 in the hippocampus and blood of patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) and to investigate whether these can be used as diagnosis and prognosis biomarkers for epilepsy. Hippocampus and blood samples were collected from 20 patients with MTLE-HS, ten of whom had a favorable surgical outcome (Engel I) and ten with an unfavorable surgical outcome (Engel III-IV). Hippocampus samples from autopsied individuals with no neurological or psychiatric medical history (necropsy samples) and blood samples from healthy individuals were used as controls. Real-time quantitative PCR (RQ-PCR) was used to analyze miRNA expression. The results showed that the expressions of these miRNAs differed quantitatively in the hippocampus and blood of patients with MTLE-HS in comparison to the respective control. This difference was most pronounced for miR-145, which was hypo-expressed in the hippocampus and hyper-expressed in the blood of MTLE-HS patients. MiRNAs miR-145, miR-181c, miR-199a and miR-1183 were hyper-expressed in the blood of patients with MTLE-HS. No statistical differences in the levels of these miRNAs in the blood or hippocampus were found between Engel I patients and Engel III-IV patients. These results suggest that the analyzed microRNAs are potential circulating biomarkers for epilepsy diagnosis.

Progesterone modulates post-traumatic epileptogenesis through regulation of BDNF-TrkB signaling and cell survival-related pathways in the rat hippocampus

Female sex hormone, progesterone, in addition to seizure modifying activity is also known as a potential protective agent against various brain injury conditions. Considering the predisposal role of traumatic brain injury (TBI) on developing post-traumatic epilepsy (PTE), the effect of progesterone on post-traumatic epileptogenesis is not investigated yet. Male Wistar rats were given a moderate focal weight drop injury (500 gr) or sham surgery and then progesterone (16 and 32mg/kg) was given daily for two consecutive weeks. On day 15 of injury, seizures were induced by administration of a GABAA receptor antagonist, pentylenetetrazole (PTZ, 30 mg/kg). Seizures were then assessed over a 1-h period using the Racine clinical rating scale. Traumatized animals that received 32 mg/kg progesterone had reduced score, duration of seizures and almost did not show tonic-clonic seizures during 60 min versus the untreated trauma group. In line with behavioral alterations, 32 mg/kg progesterone enhanced the amount of Nrf2 and HO-1 proteins and decreased the level of NF-kB, BDNF, Caspase 3 and ratio of Bax/Bcl-2 in the ipsilateral hippocampus. Additionally, the number of TUNEL-positive apoptotic cells, as well as injured dark neurons in the parietal cortex and hippocampal CA1 of 32 mg/kg-treated animals showed a significant reduction. Administration of 16 mg/kg progesterone elevated production of BDNF, Bax and Caspase 3 and decreased anti-apoptotic Bcl-2 protein. Taken together, an early administration of 32 mg/kg of progesterone after TBI for two weeks post-injury modified seizure activity. Our findings suggest that post-traumatic anti-epileptogenesis property of a high dose of progesterone partly occurs through the manipulation of BDNF-TrkB axis along with control of cell survival pathways.

Microglial phenotypes in the human epileptic temporal lobe

Microglia, the immune cells of the brain, are highly plastic and possess multiple functional phenotypes. Differences in phenotype in different regions and different states of epileptic human brain have been little studied. Here we use transcriptomics, anatomy, imaging of living cells and ELISA measurements of cytokine release to examine microglia from patients with temporal lobe epilepsies. Two distinct microglial phenotypes were explored. First we asked how microglial phenotype differs between regions of high and low neuronal loss in the same brain. Second, we asked how microglial phenotype is changed by a recent seizure. In sclerotic areas with few neurons, microglia have an amoeboid rather than ramified shape, express activation markers and respond faster to purinergic stimuli. The repairing interleukin, IL-10, regulates the basal phenotype of microglia in the CA1 and CA3 regions with neuronal loss and gliosis. To understand changes in phenotype induced by a seizure, we estimated the delay from the last seizure until tissue collection from changes in reads for immediate early gene transcripts. Pseudotime ordering of these data was validated by comparison with results from kainate-treated mice. It revealed a local and transient phenotype in which microglia secrete the human interleukin CXCL8, IL-1B and other cytokines. This secretory response is mediated in part via the NRLP3 inflammasome.

n-3 Docosapentaenoic acid-derived protectin D1 promotes resolution of neuroinflammation and arrests epileptogenesis

Epilepsy therapy is based on drugs that treat the symptoms rather than the underlying mechanisms of the disease (epileptogenesis). There are no treatments for preventing seizures or improving disease prognosis, including neurological comorbidities. The search of pathogenic mechanisms of epileptogenesis highlighted that neuroinflammatory cytokines [i.e. interleukin-1β (IL-1β), tumour necrosis factor-α (Tnf-α)] are induced in human and experimental epilepsies, and contribute to seizure generation in animal models. A major role in controlling the inflammatory response is played by specialized pro-resolving lipid mediators acting on specific G-protein coupled receptors. Of note, the role that these pathways have in epileptogenic tissue remains largely unexplored. Using a murine model of epilepsy, we show that specialized pro-resolving mechanisms are activated by status epilepticus before the onset of spontaneous seizures, but with a marked delay as compared to the neuroinflammatory response. This was assessed by measuring the time course of mRNA levels of 5-lipoxygenase (Alox5) and 15-lipoxygenase (Alox15), the key biosynthetic enzymes of pro-resolving lipid mediators, versus Il1b and Tnfa transcripts and proteins. In the same hippocampal tissue, we found a similar delayed expression of two main pro-resolving receptors, the lipoxin A₄ receptor/formyl peptide receptor 2 and the chemerin receptor. These receptors were also induced in the human hippocampus after status epilepticus and in patients with temporal lobe epilepsy. This evidence supports the hypothesis that the neuroinflammatory response is sustained by a failure to engage pro-resolving mechanisms during epileptogenesis. Lipidomic LC-MS/MS analysis showed that lipid mediator levels apt to resolve the neuroinflammatory response were also significantly altered in the hippocampus during epileptogenesis with a shift in the biosynthesis of several pro-resolving mediator families including the n-3 docosapentaenoic acid (DPA)-derived protectin D1. Of note, intracerebroventricular injection of this mediator during epileptogenesis in mice dose-dependently reduced the hippocampal expression of both Il1b and Tnfa mRNAs. This effect was associated with marked improvement in mouse weight recovery and rescue of cognitive deficit in the novel object recognition test. Notably, the frequency of spontaneous seizures was drastically reduced by 2-fold on average and the average seizure duration was shortened by 40% after treatment discontinuation. As a result, the total time spent in seizures was reduced by 3-fold in mice treated with n-3 DPA-derived protectin D1. Taken together, the present findings demonstrate that epilepsy is characterized by an inadequate engagement of resolution pathways. Boosting endogenous resolution responses significantly improved disease outcomes, providing novel treatment avenues.

Plasma kallikrein-kinin system contributes to peripheral inflammation in temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is a chronic disease, characterized by severe and refractory seizures, triggered in the hippocampus and/or amygdala, disrupting the blood-brain barrier. This disruption can sustain, or aggravate, the epileptic condition. The aim of this study was to evaluate the activation of the kallikrein-kinin system in patients with TLE, as it relates to the maintenance of blood-brain barrier. Human hippocampal sclerotic tissues removed after surgery for seizure control, plasma, and serum were used in the following assays: immunostaining for white blood cells in the TLE hippocampus, C-reactive protein in serum, quantification of plasma kallikrein (PKal) and cathepsin B (CatB) activity in serum and plasma, quantification of C1-inhibitor, analysis of high-molecular-weight kininogen (H-kininogen) fragments, and activation of plasma prekallikrein for comparison with healthy controls. Infiltration of white blood cells in the sclerotic hippocampus and a significant increase in the neutrophil/lymphocyte ratio in the blood of TLE patients were observed. High levels of C-reactive protein (TLE = 1.4 ± 0.3 µg/mL), PKal (TLE = 5.4 ± 0.4 U/mL), and CatB (TLE = 4.9 ± 0.4 U/mL) were also evident in the serum of TLE patients comparing to controls. A strong linear correlation was observed between active CatB and PKal in the serum of TLE patients (r = 0.88). High levels of cleaved H-kininogen and free PKal, and low levels of C1-inhibitor (TLE = 188 ± 12 µg/mL) were observed in the serum of TLE patients. Our data demonstrated that the plasma kallikrein-kinin system is activated in patients with TLE. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

Sema7A, a brain immune regulator, regulates seizure activity in PTZ-kindled epileptic rats

Aims

Semaphorin7A (Sema7A) plays an important role in the immunoregulation of the brain. In our study, we aimed to investigate the expression patterns of Sema7A in epilepsy and further explore the roles of Sema7A in the regulation of seizure activity and the inflammatory response in PTZ‐kindled epileptic rats.

Methods

First, we measured the Sema7A expression levels in patients with temporal lobe epilepsy (TLE) and in rats of a PTZ‐kindled epilepsy rat model. Second, to explore the role of Sema7A in the regulation of seizure activity, we conducted epilepsy‐related behavioral experiments after knockdown and overexpression of Sema7A in the rat hippocampal dentate gyrus (DG). Possible Sema7A‐related brain immune regulators (eg, ERK phosphorylation, IL‐6, and TNF‐α) were also investigated. Additionally, the growth of mossy fibers was visualized by anterograde tracing using injections of biotinylated dextran amine (BDA) into the DG region.

Results

Sema7A expression was markedly upregulated in the brain tissues of TLE patients and rats of the epileptic model after PTZ kindling. After knockdown of Sema7A, seizure activity was suppressed based on the latency to the first epileptic seizure, number of seizures, and duration of seizures. Conversely, overexpression of Sema7A promoted seizures. Overexpression of Sema7A increased the expression levels of the inflammatory cytokines, IL‐6 and TNF‐α, ERK phosphorylation, and growth of mossy fibers in PTZ‐kindled epileptic rats.

Conclusion

Sema7A is upregulated in the epileptic brain and plays a potential role in the regulation of seizure activity in PTZ‐kindled epileptic rats, which may be related to neuroinflammation. Sema7A promotes the inflammatory cytokines TNF‐α and IL‐6 as well as the growth of mossy fibers through the ERK pathway, suggesting that Sema7A may promote seizures by increasing neuroinflammation and activating pathological neural circuits. Sema7A plays a critical role in epilepsy and could be a potential therapeutic target for this neurological disorder.

Seizures Are Associated with Blood-Brain Barrier Disruption in a Piglet Model of Neonatal Hypoxic-Ischaemic Encephalopathy

Seizures in the neonatal period are most often symptomatic of central nervous system (CNS) dysfunction and the most common cause is hypoxic-ischaemic encephalopathy (HIE). Seizures are associated with poor long-term outcomes and increased neuropathology. Blood-brain barrier (BBB) disruption and inflammation may contribute to seizures and increased neuropathology but are incompletely understood in neonatal HIE. The aim of this study was to investigate the impact of seizures on BBB integrity in a preclinical model of neonatal hypoxic-ischaemic (HI) injury. Piglets (age: <24 h) were subjected to a 30-min HI insult followed by recovery to 72 h post-insult. Amplitude-integrated electroencephalography (aEEG) was performed and seizure burden and background aEEG pattern were analysed. BBB disruption was evaluated in the parietal cortex and hippocampus by means of immunohistochemistry and Western blot. mRNA and protein expression of tight-junction proteins (zonula-occludens 1 [ZO1], occludin [OCLN], and claudin-5 [CLDN5]) was assessed using quantitative polymerase chain reaction (qPCR) and Western blot. In addition, mRNA from genes associated with BBB disruption vascular endothelial growth factor (VEGF) and matrix metalloproteinase 2 (MMP2) as well as inflammatory cytokines and chemokines was assessed with qPCR. Piglets that developed seizures following HI (HI-Sz) had significantly greater injury, as demonstrated by poorer aEEG background pattern scores, lower neurobehavioural scores, and greater histopathology. HI-Sz animals had severe IgG extravasation into brain tissue and uptake into neurons as well as significantly greater levels of IgG in both brain regions as assessed by Western blot. IgG protein in both brain regions was significantly associated with seizure burden, aEEG pattern scores, and neurobehavioural scores. There was no difference in mRNA expression of the tight junctions, however a significant loss of ZO1 and OCLN protein was observed in the parietal cortex. The inflammatory genes TGFβ, IL1β, IL8, IL6, and TNFα were significantly upregulated in HI-Sz animals. MMP2 was significantly increased in animals with seizures compared with animals without seizures. Increasing our understanding of neuropathology associated with seizure is vital because of the association between seizure and poor outcomes. Investigating the BBB is a major untapped area of research and a potential avenue for novel treatments.

The Anticonvulsant Effects of Baldrinal on Pilocarpine-Induced convulsion in Adult Male Mice

Epilepsy is a prevalent neurological disorder that was reported to affect about 56 million people in the world. Approximately one-third of the epileptic patients that suffer from seizures do not receive effective medical treatment. The aim of this study was to determine the potential anticonvulsant activities of Baldrinal (BAL) with a mouse model of pilocarpine (PILO)-induced epilepsy. The mice were treated with different doses of BAL or sodium valproate prior to PILO injection. Spontaneous and evoked seizures were evaluated from EEG recordings, and their severity was tested by the Racine scale. In addition, the brain tissues were analyzed for histological changes, and the in situ levels of glutamic acid (Glu) and gamma-aminobutyric acid (GABA) were also measured. Activation of astrocytes in the hippocampus was measured. PILO-treated mice showed a significant increase in Glu levels, which was restored by BAL. In addition, BAL treatment also reduced the rate of seizures in the epileptic mice, and ameliorated the increased levels of NMDAR1, BDNF, IL-1β and TNF-α. Taken together, BAL has a potential antiepileptic effect, which may be mediated by reducing the inflammatory response in the PILO-induced brain and restoring the balance of GABAergic and glutamatergic neurons.

The holy grail of epilepsy prevention: Preclinical approaches to antiepileptogenic treatments

A variety of acute brain insults can induce epileptogenesis, a complex process that results in acquired epilepsy. Despite advances in understanding mechanisms of epileptogenesis, there is currently no approved treatment that prevents the development or progression of epilepsy in patients at risk. The current concept of epileptogenesis assumes a window of opportunity following acute brain insults that allows intervention with preventive treatment. Recent results suggest that injury-induced epileptogenesis can be a much more rapid process than previously thought, suggesting that the 'therapeutic window' may only be open for a brief period, as in stroke therapy. However, experimental data also suggest a second, possibly delayed process ("secondary epileptogenesis") that influences the progression and refractoriness of the epileptic state over time, allowing interfering with this process even after onset of epilepsy. In this review, both methodological issues in preclinical drug development and novel targets for antiepileptogenesis will be discussed. Several promising drugs that either prevent epilepsy (antiepileptogenesis) or slow epilepsy progression and alleviate cognitive or behavioral comorbidities of epilepsy (disease modification) have been described in recent years, using diverse animal models of acquired epilepsy. Promising agents include TrkB inhibitors, losartan, statins, isoflurane, anti-inflammatory and anti-oxidative drugs, the SV2A modulator levetiracetam, and epigenetic interventions. Research on translational target validity and on prognostic biomarkers that can be used to stratify patients (or experimental animals) at high risk of developing epilepsy will hopefully soon lead to proof-of-concept clinical trials with the most promising drugs, which will be essential to make prevention of epilepsy a reality. 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'.

Network and Pathway-Based Analysis of Single-Nucleotide Polymorphism of miRNA in Temporal Lobe Epilepsy

Temporal lobe epilepsy (TLE) is a complex disease with its pathogenetic mechanism still unclear. Single-nucleotide polymorphisms (SNPs) of miRNA (miRSNPs) are SNPs located on miRNA genes or target sites of miRNAs, which have been proved to be associated with neuropsychic disease development by interfering with miRNA-mediated regulatory function. In this study, we integrated TLE-related risk genes and risk pathways multi-dimensionally based on public data resources. Furthermore, we systematically screened candidate functional miRSNPs for TLE and constructed a TLE-associated pathway-based miRSNP switching network, which included 92 miRNAs that target 12 TLE risk pathways. Moreover, we dissected thoroughly the correlation between 5 risk genes of 4 risk pathways and TLE development. Additionally, the biological function of several candidate miRSNPs were validated by luciferase reporter assay. In silico approach facilitates to select potential "miRSNP-miRNA-risk gene-pathway" axis for experimental validation, which provided new insights into the mechanism of miRSNPs as potential genetic risk factors of TLE.

Microglial nodules provide the environment for pathogenic T cells in human encephalitis

Microglia nodule formation is a common feature in inflammatory brain diseases mediated by T lymphocytes such as viral and paraneoplastic encephalitis, multiple sclerosis, and Rasmussen encephalitis (RE). However, its role has not been fully understood yet. We hypothesized that, in RE, microglial nodules provide an environment for the initiation of the later dominating T-cell cytotoxicity. In RE stage 0, small primary microglia nodules could be identified in the absence of T cells. These primary nodules showed inflammasome activation and endosomal Toll-like receptor upregulation. In stage 1, T cells migrate into the parenchyma and intermingle with microglial cells, thereby forming secondary nodules in which neurons are destroyed. Whole-genome transcriptome analysis at this point showed upregulation of several inflammatory pathways including interferon signaling and major histocompatibility complex-I signaling. Inflammatory profiles, like the ones observed in RE, could be induced upon TLR3 stimulation in neonatal microglial cell cultures. Taken together, our results point towards activation of endosomal TLRs, resulting in increased interferon signaling, inflammasome activation, and chemokine upregulation as early steps in RE pathogenesis. This activity sets the scene for subsequent infiltration of T cells and destruction of neurons. Similar to RE, this microglial microenvironment might be a crucial step in other T-cell-mediated inflammatory brain diseases.

Smad Anchor for Receptor Activation and Phospho-Smad3 Were Upregulated in Patients with Temporal Lobe Epilepsy

Smad anchor for receptor activation (SARA) is an important regulator of transforming growth factor β (TGF-β) signaling by recruiting Smad2/3 to TGF-β receptors. We recently demonstrated that the expressions of SARA and level of downstream phospho-Smad3 (p-Smad3) were upregulated in the brain in the epileptic rat model, but were never examined in patients with temporal lobe epilepsy (TLE). In this study, we examined the expressions of SARA and level of p-Smad3 in brain tissues of TLE patients using immunohistochemistry and western blot to demonstrate that SARA activation in neurons is sufficient to facilitate TGF- β pathway in patients to regulate epilepsy. We found that the expressions of SARA and level of p-Smad3 were significantly upregulated in neurons of the temporal cortex of TLE patients compared to controls. Moreover, SARA and p-Smad3 were strongly stained in the cytoplasm in the temporal cortex of TLE patients. Our results indicate that upregulation of SARA and p-Smad3 in cortex neurons might be involved in the development of intractable temporal lobe epilepsy.

Kininogen Level in the Cerebrospinal Fluid May Be a Potential Biomarker for Predicting Epileptogenesis

Purpose: Epilepsy is a highly disabling neurological disorder. Brain insult is the most critical cause of epilepsy in adults. This study aimed to find reliable and efficient biomarkers for predicting secondary epilepsy. Materials and methods: The LiCl-pilocarpine (LiCl-Pilo) chronic epilepsy rat model was used, and rat cerebrospinal fluid (CSF) was collected 5 days after status epilepticus (SE). The CSF was analyzed using the label-free LC-ESI-Q-TOF-MS/MS. Differential expression of proteins was confirmed using enzyme-linked immunosorbent assay (ELISA) and Western blotting. The corresponding protein level in the CSF of patients with encephalitis in the postacute phase was determined using ELISA and compared between patients with and without symptomatic epilepsy after encephalitis during a 2-year follow-up. Results: The proteomics and ELISA results showed that the protein level of kininogen (KNG) was obviously elevated in both CSF and hippocampus, but not in serum, 5 days after the onset of SE in LiCl-Pilo chronic epilepsy model rats. In patients with encephalitis, the protein level of KNG in the CSF in the postacute phase was significantly elevated in patients with a recurrent epileptic seizure during a 2-year follow-up than in patients without a recurrent seizure. Conclusion: KNG in the CSF may serve as a potential biomarker for predicting epileptogenesis in patients with encephalitis.

Network pharmacology for antiepileptogenesis: Tolerability and neuroprotective effects of novel multitargeted combination treatments in nonepileptic vs. post-status epilepticus mice

Network-based approaches in drug discovery comprise both development of novel drugs interacting with multiple targets and repositioning of drugs with known targets to form novel drug combinations that interact with cellular or molecular networks whose function is disturbed in a disease. Epilepsy is a complex network phenomenon that, as yet, cannot be prevented or cured. We recently proposed multitargeted, network-based approaches to prevent epileptogenesis by combinations of clinically available drugs chosen to impact diverse epileptogenic processes. In order to test this strategy preclinically, we developed a multiphase sequential study design for evaluating such drug combinations in rodents, derived from human clinical drug development phases. Because pharmacokinetics of such drugs are known, only the tolerability of novel drug combinations needs to be evaluated in Phase I in öhealthy" controls. In Phase IIa, tolerability is assessed following an epileptogenic brain insult, followed by antiepileptogenic efficacy testing in Phase IIb. Here, we report Phase I and Phase IIa evaluation of 7 new drug combinations in mice, using 10 drugs (levetiracetam, topiramate, gabapentin, deferoxamine, fingolimod, ceftriaxone, α-tocopherol, melatonin, celecoxib, atorvastatin) with diverse mechanisms thought to be important in epileptogenesis. Six of the 7 drug combinations were well tolerated in mice during prolonged treatment at the selected doses in both controls and during the latent phase following status epilepticus induced by intrahippocampal kainate. However, none of the combinations prevented hippocampal damage in response to kainate, most likely because treatment started only 16-18 h after kainate. This suggests that antiepileptogenic or disease-modifying treatment may need to start earlier after the brain insult. The present data provide a rich collection of tolerable, network-based combinatorial therapies as a basis for antiepileptogenic or disease-modifying efficacy testing.

Annexin A1-derived peptide Ac2-26 in a pilocarpine-induced status epilepticus model: anti-inflammatory and neuroprotective effects

Background

The inflammatory process has been described as a crucial mechanism in the pathophysiology of temporal lobe epilepsy. The anti-inflammatory protein annexin A1 (ANXA1) represents an interesting target in the regulation of neuroinflammation through the inhibition of leukocyte transmigration and the release of proinflammatory mediators. In this study, the role of the ANXA1-derived peptide Ac_2-26 in an experimental model of status epilepticus (SE) was evaluated.

Methods

Male Wistar rats were divided into Naive, Sham, SE and SE+Ac_2-26 groups, and SE was induced by intrahippocampal injection of pilocarpine. In Sham animals, saline was applied into the hippocampus, and Naive rats were only handled. Three doses of Ac_2-26 (1 mg/kg) were administered intraperitoneally (i.p.) after 2, 8 and 14 h of SE induction. Finally, 24 h after the experiment-onset, rats were euthanized for analyses of neuronal lesion and inflammation.

Results

Pilocarpine induced generalised SE in all animals, causing neuronal damage, and systemic treatment with Ac_2-26 decreased neuronal degeneration and albumin levels in the hippocampus. Also, both SE groups showed an intense influx of microglia, which was corroborated by high levels of ionised calcium binding adaptor molecule 1(Iba-1) and monocyte chemoattractant protein-1 (MCP-1) in the hippocampus. Ac_2-26 reduced the astrocyte marker (glial fibrillary acidic protein; GFAP) levels, as well as interleukin-1β (IL-1β), interleukin-6 (IL-6) and growth-regulated alpha protein (GRO/KC). These effects of the peptide were associated with the modulation of the levels of formyl peptide receptor 2, a G-protein-coupled receptor that binds to Ac_2-26, and the phosphorylated extracellular signal-regulated kinase (ERK) in the hippocampal neurons.

Conclusions

The data suggest a neuroprotective effect of Ac_2-26 in the epileptogenic processes through downregulation of inflammatory mediators and neuronal loss.

Suppressing pro-inflammatory prostaglandin signaling attenuates excitotoxicity-associated neuronal inflammation and injury

Glutamate receptor-mediated excitotoxicity is a common pathogenic process in many neurological conditions including epilepsy. Prolonged seizures induce elevations in extracellular glutamate that contribute to excitotoxic damage, which in turn can trigger chronic neuroinflammatory reactions, leading to secondary damage to the brain. Blocking key inflammatory pathways could prevent such secondary brain injury following the initial excitotoxic insults. Prostaglandin E2 (PGE₂) has emerged as an important mediator of neuroinflammation-associated injury, in large part via activating its EP2 receptor subtype. Herein, we investigated the effects of EP2 receptor inhibition on excitotoxicity-associated neuronal inflammation and injury in vivo. Utilizing a bioavailable and brain-permeant compound, TG6-10-1, we found that pharmacological inhibition of EP2 receptor after a one-hour episode of kainate-induced status epilepticus (SE) in mice reduced seizure-promoted functional deficits, cytokine induction, reactive gliosis, blood-brain barrier impairment, and hippocampal damage. Our preclinical findings endorse the feasibility of blocking PGE₂/EP2 signaling as an adjunctive strategy to treat prolonged seizures. The promising benefits from EP2 receptor inhibition should also be relevant to other neurological conditions in which excitotoxicity-associated secondary damage to the brain represents a pathogenic event.

An AIE-based self-assembled fluorescent probe for COX-2 imaging

The first AIE-based fluorescent probe TPI-IMC was developed for imaging of cyclooxygenase-2 (COX-2) in normal cells and cancer cells.

Anti-Oxidant and Anti-Apoptotic Effects of Berberine in Pentylenetetrazole-Induced Kindling Model in Rat

Background and Purpose

Berberine (BBR) is derived from the Berberis species and has demonstrated beneficial effects in various neurodegenerative disorders in animal models. The objective of this study was to evaluate the antiepileptic, antioxidative, and anti-apoptotic effects of BBR in a pentylenetetrazole (PTZ)-induced kindling model of epilepsy in rats.

Methods

A total of 30 male Wistar rats were randomly assigned to receive BBR (100 mg/kg, oral), sodium valproate (200 mg/kg, i.p.), or saline (0.9% NaCl, i.p.) followed by PTZ (35 mg/kg, i.p.) on alternate days until the animal developed kindling or for 10 weeks. Histopathological examination of the hippocampus; DNA fragmentation study; tests for malondialdehyde, superoxide dismutase, glutathione peroxidase, and reduced glutathione; and gene expression studies (nrf2, bcl-2, bax, and caspase 3) were conducted on whole brain tissue after 10 weeks or kindling.

Results

The percentage of kindled animals, histopathological score, malondialdehyde level, and caspase 3 gene expression were significantly lower in the BBR group than in the PTZ group. Superoxide dismutase levels, reduced glutathione levels, and bcl-2 gene expression were significantly higher in the BBR group than in the PTZ group.

Conclusions

The present study demonstrated the anti-epileptogenic effect of BBR, which may be due to antioxidant and anti-apoptotic properties of the PTZ-induced kindling model of epilepsy.

Oxidative stress and inflammation in a spectrum of epileptogenic cortical malformations: molecular insights into their interdependence

Oxidative stress (OS) occurs in brains of patients with epilepsy and coincides with brain inflammation, and both phenomena contribute to seizure generation in animal models. We investigated whether expression of OS and brain inflammation markers co-occurred also in resected brain tissue of patients with epileptogenic cortical malformations: hemimegalencephaly (HME), focal cortical dysplasia (FCD) and cortical tubers in tuberous sclerosis complex (TSC). Moreover, we studied molecular mechanisms linking OS and inflammation in an in vitro model of neuronal function. Untangling interdependency and underlying molecular mechanisms might pose new therapeutic strategies for treating patients with drug-resistant epilepsy of different etiologies. Immunohistochemistry was performed for specific OS markers xCT and iNOS and brain inflammation markers TLR4, COX-2 and NF-κB in cortical tissue derived from patients with HME, FCD IIa, IIb and TSC. Additionally, we studied gene expression of these markers using the human neuronal cell line SH-SY5Y in which OS was induced using H₂ O₂ . OS markers were higher in dysmorphic neurons and balloon/giant cells in cortex of patients with FCD IIb or TSC. Expression of OS markers was positively correlated to expression of brain inflammation markers. In vitro, 100 µM, but not 50 µM, of H₂ O₂ increased expression of TLR4, IL-1β and COX-2. We found that NF-κB signaling was activated only upon stimulation with 100 µM H₂ O₂ leading to upregulation of TLR4 signaling and IL-1β. The NF-κB inhibitor TPCA-1 completely reversed this effect. Our results show that OS positively correlates with neuroinflammation and is particularly evident in brain tissue of patients with FCD IIb and TSC. In vitro, NF-κB is involved in the switch to an inflammatory state after OS. We propose that the extent of OS can predict the neuroinflammatory state of the brain. Additionally, antioxidant treatments may prevent the switch to inflammation in neurons thus targeting multiple epileptogenic processes at once.

Humble beginnings with big goals: Small molecule soluble epoxide hydrolase inhibitors for treating CNS disorders

Soluble epoxide hydrolase (sEH) degrades epoxides of fatty acids including epoxyeicosatrienoic acid isomers (EETs), which are produced as metabolites of the cytochrome P450 branch of the arachidonic acid pathway. EETs exert a variety of largely beneficial effects in the context of inflammation and vascular regulation. sEH inhibition is shown to be therapeutic in several cardiovascular and renal disorders, as well as in peripheral analgesia, via the increased availability of anti-inflammatory EETs. The success of sEH inhibitors in peripheral systems suggests their potential in targeting inflammation in the central nervous system (CNS) disorders. Here, we describe the current roles of sEH in the pathology and treatment of CNS disorders such as stroke, traumatic brain injury, Parkinson's disease, epilepsy, cognitive impairment, dementia and depression. In view of the robust anti-inflammatory effects of stem cells, we also outlined the potency of stem cell treatment and sEH inhibitors as a combination therapy for these CNS disorders. This review highlights the gaps in current knowledge about the pathologic and therapeutic roles of sEH in CNS disorders, which should guide future basic science research towards translational and clinical applications of sEH inhibitors for treatment of neurological diseases.

Serum level of C-reactive protein and interleukin-6 in children with drug-resistant epilepsy

There is increasing evidence that chronic inflammation affects the pathophysiology of epilepsy, especially the drug-resistant type. Drug-resistant epilepsy is a challenging condition, because of the difficulties in its management, and its unclear epileptogenesis. This study is looking at C-reactive protein (CRP) and interleukin-6 (IL-6) levels in those with drug-resistant epilepsy and the correlation of these levels with seizure frequency. Hence, 40 children with drug-resistant epilepsy were included in this study and compared with 20 healthy volunteers (as a control group). Participants were aged between 5 and 15 years. Patients were divided into two subgroups, those with daily seizures (Group A1) and those with monthly seizures (Group A2). Serum levels of CRP and IL-6 were measured in all participants. The clinical characteristics, electroencephalography, and magnetic resonance imaging (MRI) findings were then compared. CRP levels were significantly higher in Group A1, at 21.88–93.29 mg/L than both Group A2 and the control group, at 3.02–40.37 mg/L and 2.23–13.18 mg/L, P < 0.01 and P < 0.001, respectively. The IL-6 levels were also significantly higher in Group A1, at 153.60–597.80 ng/L than in both Group A2 and the control group, at 97.40–232.50 ng/L and 12.00–96.30 ng/L, P < 0.01 and P < 0.001, respectively. Significantly higher levels of CRP and IL-6 were associated with earlier age of onset ( P < 0.01), seizure frequency ( P < 0.05), and the frequency of status epilepticus ( P < 0.01). Moreover, frequent-generalized motor seizures are correlated with elevated CRP and IL-6 levels. As a result, this systemic inflammatory reaction in children may contribute to drug-resistant seizure and potentially could be used as biomarkers to be correlated with disease severity and prognosis.

Soman-induced status epilepticus, epileptogenesis, and neuropathology in carboxylesterase knockout mice treated with midazolam

Objective

Exposure to chemical warfare nerve agents (CWNAs), such as soman (GD), can induce status epilepticus (SE) that becomes refractory to benzodiazepines when treatment is delayed, leading to increased risk of epileptogenesis, severe neuropathology, and long‐term behavioral and cognitive deficits. Rodent models, widely used to evaluate novel medical countermeasures (MCMs) against CWNA exposure, normally express plasma carboxylesterase, an enzyme involved in the metabolism of certain organophosphorus compounds. To better predict the efficacy of novel MCMs against CWNA exposure in human casualties, it is crucial to use appropriate animal models that mirror the human condition. We present a comprehensive characterization of the seizurogenic, epileptogenic, and neuropathologic effects of GD exposure with delayed anticonvulsant treatment in the plasma carboxylesterase knockout (ES1−/−) mouse.

Methods

Electroencephalography (EEG) electrode‐implanted ES1−/− and wild‐type (C57BL/6) mice were exposed to various seizure‐inducing doses of GD, treated with atropine sulfate and the oxime HI‐6 at 1 minute after exposure, and administered midazolam at 15‐30 minutes following the onset of seizure activity. The latency of acute seizure onset and spontaneous recurrent seizures (SRS) was assessed, as were changes in EEG power spectra. At 2 weeks after GD exposure, neurodegeneration and neuroinflammation were assessed.

Results

GD‐exposed ES1−/− mice displayed a dose‐dependent response in seizure severity. Only ES1−/− mice exposed to the highest tested dose of GD developed SE, subchronic alterations in EEG power spectra, and SRS. Degree of neuronal cell loss and neuroinflammation were dose‐dependent; no significant neuropathology was observed in C57BL/6 mice or ES1−/− mice exposed to lower GD doses.

Significance

The US Food and Drug Administration (FDA) animal rule requires the use of relevant animal models for the advancement of MCMs against CWNAs. We present evidence that argues for the use of the ES1−/− mouse model to screen anticonvulsant, antiepileptic, and/or neuroprotective drugs against GD‐induced toxicity, as well as to identify mechanisms of GD‐induced epileptogenesis.

The role of Mean Platelet Volume/platelet count Ratio and Neutrophil to Lymphocyte Ratio on the risk of Febrile Seizure

Systemic inflammatory response has been implicated as a contributor to the onset of febrile seizures (FS). The four novel indices of the inflammatory response such as, neutrophil-to-lymphocyte ratio (NLR), mean platelet volume (MPV), platelet count (PLT) ratio and red blood cell distribution width (RDW) have been investigated in FS susceptibility and FS types (simple febrile seizure and complex febrile seizure). However, the potential role of these inflammatory markers and MPV/PLT ratio (MPR) in Chinese children with FS has yet to be fully determined. This study investigated the relevance of NLR, MPV, PLT, MPR and RDW in febrile children with and without seizures. 249 children with FS and 249 age matched controls were included in this study. NLR and MPR were calculated from complete blood cell counts prior to therapy. Differences in age, gender and these inflammatory markers between the FS group and the control group were evaluated using the chi-square test, t-test or logistic regression analysis. Receiver Operating Characteristic (ROC) curve was used to determine the optimal cut-off value of NLR and MPR for FS risk. Interactions between NLR and MPR on the additive scale were calculated by using the relative excess risk due to interaction (RERI), the proportion attributable to interaction (AP), and the synergy index (S). It has been shown that the elevated NLR and MPR levels were associated with increased risk of FS. The optimal cut-off values of NLR and MPR for FS risk were 1.13 and 0.0335 with an area under the curve (AUC) of 0.768 and 0.689, respectively. Additionally, a significant synergistic interaction between NLR and MPR was found on an additive scale. The mean levels of MPV were lower and NLR levels were higher in complex febrile seizure (CFS) than simple febrile seizure (SFS), and the differences were statistically significant. ROC analysis showed that the optimal cut-off value for NLR was 2.549 with 65.9% sensitivity and 57.5% specificity. However, no statistically significant differences were found regarding average values of MPR and RDW between CFS and SFS. In conclusion, elevated NLR and MPR add evidence to the implication of white cells subsets in FS risk, and our results confirmed that NLR is an independent, albeit limited, predictor in differentiating between CFS and SFS. Moreover, NLR and MPR may have a synergistic effect that can influence the occurrence of FS.