Interleukin-1 in Febrile Infection-Related Epilepsy Syndrome

Febrile infection-related epilepsy syndrome (FIRES) characteristically affects previously healthy children, who experience a sudden and explosive onset of super-refractory status epilepticus preceded by febrile infection and accompanied by fulminant neurogenic inflammation. FIRES, however, can affect individuals of all ages and is a subcategory of new-onset refractory status epilepticus. This definition of FIRES excludes febrile status epilepticus in infants. FIRES is a rare type of epileptic encephalopathy with rapidly progressive onset of seizures and a devastating prognosis, as drug-resistant epilepsy often follows without a latency period. Although the exact pathogenesis of FIRES has not been elucidated, a functional deficiency in the endogenous interleukin-1 receptor antagonist has been implicated in a genetic predisposition to FIRES. Dysregulation of the interleukin-1β–interleukin-1 receptor 1 (IL-1β–IL-1R1) signaling pathway appears to be involved in the pathogenesis of FIRES. In this review, the authors summarize the definition of FIRES, IL-1β–IL-1R1 signaling, the nucleotide-binding oligomerization domain the NLRP3 inflammasome, and IL-1 targeted therapy for FIRES

Confounding effect of EEG implantation surgery: Inadequacy of surgical control in a two hit model of temporal lobe epilepsy

AbstractIn rodent models of epilepsy, EEG implantation surgery is an essential modality to evaluate electrographic seizures. The inflammatory consequences of EEG electrode-implantation and their resultant effects on seizure susceptibility are unclear. We evaluated electrode-implantation in a two-hit model of epileptogenesis in C57BL/6 mice that included brief, recurrent febrile seizures (FS) at P14 and kainic acid induced seizures (KA-SZ) at P28. During KA-SZ, latencies to first electrographic and behavioral seizures, seizure severity, and KA dose sensitivity were measured. Mice that received subdural screw electrode implants at P25 for EEG monitoring at P28 had significantly shorter latencies to seizures than sham mice, regardless of early life seizure experience. Electrode-implanted mice were sensitive to low dose KA as shown by high mortality rate at KA doses above 10mg/kg. We then directly compared electrode-implantation and KA-SZ in seizure naive CX3CR1GFP/+ transgenic C57BL/6 mice, wherein microglia express green fluorescent protein (GFP), to determine if microglia activation related to surgery was associated with the increased seizure susceptibility in electrode-implanted mice from the two-hit model. Hippocampal microglia activation, as demonstrated by percent area GFP signal and GFP positive cell counts, prior to seizures was indistinguishable between electrode-implanted mice and controls, but was significantly greater in electrode-implanted mice following seizures. Electrode-implantation had a confounding priming effect on the inflammatory response to subsequent seizures

Cellular injury and neuroinflammation in children with chronic intractable epilepsy

<p>Abstract</p> <p>Objective</p> <p>To elucidate the presence and potential involvement of brain inflammation and cell death in neurological morbidity and intractable seizures in childhood epilepsy, we quantified cell death, astrocyte proliferation, microglial activation and cytokine release in brain tissue from patients who underwent epilepsy surgery.</p> <p>Methods</p> <p>Cortical tissue was collected from thirteen patients with intractable epilepsy due to focal cortical dysplasia (6), encephalomalacia (5), Rasmussen's encephalitis (1) or mesial temporal lobe epilepsy (1). Sections were processed for immunohistochemistry using markers for neuron, astrocyte, microglia or cellular injury. Cytokine assay was performed on frozen cortices. Controls were autopsy brains from eight patients without history of neurological diseases.</p> <p>Results</p> <p>Marked activation of microglia and astrocytes and diffuse cell death were observed in epileptogenic tissue. Numerous fibrillary astrocytes and their processes covered the entire cortex and converged on to blood vessels, neurons and microglia. An overwhelming number of neurons and astrocytes showed DNA fragmentation and its magnitude significantly correlated with seizure frequency. Majority of our patients with abundant cell death in the cortex have mental retardation. IL-1beta, IL-8, IL-12p70 and MIP-1beta were significantly increased in the epileptogenic cortex; IL-6 and MCP-1 were significantly higher in patients with family history of epilepsy.</p> <p>Conclusions</p> <p>Our results suggest that active neuroinflammation and marked cellular injury occur in pediatric epilepsy and may play a common pathogenic role or consequences in childhood epilepsy of diverse etiologies. Our findings support the concept that immunomodulation targeting activated microglia and astrocytes may be a novel therapeutic strategy to reduce neurological morbidity and prevent intractable epilepsy.</p

Role of Brain Inflammation in Epileptogenesis

Inflammation is known to participate in the mediation of a growing number of acute and chronic neurological disorders. Even so, the involvement of inflammation in the pathogenesis of epilepsy and seizure-induced brain damage has only recently been appreciated. Inflammatory processes, including activation of microglia and astrocytes and production of proinflammatory cytokines and related molecules, have been described in human epilepsy patients as well as in experimental models of epilepsy. For many decades, a functional role for brain inflammation has been implied by the effective use of anti-inflammatory treatments, such as steroids, in treating intractable pediatric epilepsy of diverse causes. Conversely, common pediatric infectious or autoimmune diseases are often accompanied by seizures during the course of illness. In addition, genetic susceptibility to inflammation correlated with an increased risk of epilepsy. Mounting evidence thus supports the hypothesis that inflammation may contribute to epileptogenesis and cause neuronal injury in epilepsy. We provide an overview of the current knowledge that implicates brain inflammation as a common predisposing factor in epilepsy, particularly childhood epilepsy

Age-dependent changes in intrinsic neuronal excitability in subiculum after status epilepticus.

Kainic acid-induced status epilepticus (KA-SE) in mature rats results in the development of spontaneous recurrent seizures and a pattern of cell death resembling hippocampal sclerosis in patients with temporal lobe epilepsy. In contrast, KA-SE in young animals before postnatal day (P) 18 is less likely to cause cell death or epilepsy. To investigate whether changes in neuronal excitability occur in the subiculum after KA-SE, we examined the age-dependent effects of SE on the bursting neurons of subiculum, the major output region of the hippocampus. Patch-clamp recordings were used to monitor bursting in pyramidal neurons in the subiculum of rat hippocampal slices. Neurons were studied either one or 2-3 weeks following injection of KA or saline (control) in immature (P15) or more mature (P30) rats, which differ in their sensitivity to KA as well as the long-term sequelae of the KA-SE. A significantly greater proportion of subicular pyramidal neurons from P15 rats were strong-bursting neurons and showed increased frequency-dependent bursting compared to P30 animals. Frequency-dependent burst firing was enhanced in P30, but not in P15 rats following KA-SE. The enhancement of bursting induced by KA-SE in more mature rats suggests that the frequency-dependent limitation of repetitive burst firing, which normally occurs in the subiculum, is compromised following SE. These changes could facilitate the initiation of spontaneous recurrent seizures or their spread from the hippocampus to other parts of the brain

Timeline for studying the effects of KA-SE.

<p>Relatively mature (30 day-old) and immature (15 day-old) rats were injected with either saline (control) or KA. About 80% of rats injected with KA experienced seizures for over 1 hr after the injections; only these animals that experienced status epilepticus were used for all subsequent experiments. For P30 rats injected with saline or KA, slices were prepared either 5–7 days after injection (P30,36 control; P30,36 KA) or 12–13 days after injection (P30,42 control; P30,42 KA). For P15 rats injected with saline or KA, hippocampal slices were made 5–7 days after injection (P15,21 control; P15,21 KA) or 20–22 days after injection (P15,36 control; P15,36 KA).</p

Feasibility of a mobile cognitive intervention in childhood absence epilepsy

Children with childhood absence epilepsy (CAE) frequently present with cognitive comorbidities and school performance concerns. The present study evaluated the feasibility of an intervention for such comorbidities using a mobile cognitive therapy application on an iPad. Eight children with CAE and school concerns aged 7-11 participated in a four-week intervention. They were asked to use the application for 80 minutes per week (20 minutes/day, 4 times/week). Parents and children completed satisfaction surveys regarding the application. Participants were evaluated before and after the intervention using the Cognitive Domain of the NIH Toolbox and by parental completion of the Behavioral Rating Inventory of Executive Function (BRIEF). All eight patients completed the study, using the iPad for an average of 78 minutes/week. Children and parents reported high satisfaction with the application. Though a demonstration of efficacy was not the focus of the study, performance improvements were noted on a processing speed task and on a measure of fluid intelligence. An iPad based cognitive therapy was found to be a feasible intervention for children with CAE

Schematic representation of developmental and KA-SE-induced changes in repetitive bursting in subiculum.

<p><b>A</b>. Digital representation of bursting at four stages and conditions. Double and single vertical lines represent bursts and single spikes, respectively. Each train represents the response to five stimuli. <b>B</b>. Schematic plots of the number of bursts (in response to five stimuli) versus frequency at each of the stages and conditions shown. Arrows indicate the decreased bursting during maturation and the increased bursting in the latent period following status epilepticus.</p