Serum cytokine levels are altered in patients with West syndrome

Interleukins in Epilepsy: Friend or Foe

Epilepsy is a chronic neurological disorder with recurrent unprovoked seizures, affecting ~ 65 million worldwide. Evidence in patients with epilepsy and animal models suggests a contribution of neuroinflammation to epileptogenesis and the development of epilepsy. Interleukins (ILs), as one of the major contributors to neuroinflammation, are intensively studied for their association and modulatory effects on ictogenesis and epileptogenesis. ILs are commonly divided into pro- and anti-inflammatory cytokines and therefore are expected to be pathogenic or neuroprotective in epilepsy. However, both protective and destructive effects have been reported for many ILs. This may be due to the complex nature of ILs, and also possibly due to the different disease courses that those ILs are involved in. In this review, we summarize the contributions of different ILs in those processes and provide a current overview of recent research advances, as well as preclinical and clinical studies targeting ILs in the treatment of epilepsy.

Altered serum levels of platelet-derived growth factor receptor β and cluster of differentiation 13 suggest a role for pericytes in West syndrome

BACKGROUND

Pericytes play a role in the maintenance of the blood-brain barrier and neuroinflammation, attracting attention as to whether they are also involved in the pathogenesis of epilepsy.This study aimed to explore the relationship between West syndrome and pericytes.

METHODS

Eighteen Japanese pediatric West syndrome patients and nine controls aged 2 years or younger were retrospectively enrolled in this study. We assessed theserumlevels of pericyte markers, serum PDGFRβ (platelet-derived growth factor receptorβ),CD13 (aminopeptidase N), and 27 cytokines in 17 pediatric patients with West syndrome and the control group.

RESULTS

Patients with West syndrome exhibited significantly increased CD13 and decreased PDGFRβ levels, compared with controls but not serum cytokine levels. These values did not differ significantly between symptomatic and idiopathic West syndrome.

CONCLUSION

Pericytes might be implicated in the pathogenesis of West syndrome.

Distribution of peripheral blood mononuclear cell subtypes in patients with West syndrome: Impact of synacthen treatment

BACKGROUND

West Syndrome (WS) is an epileptic encephalopathy that typically occurs in infants and is characterized by hypsarrhythmia, infantile spasms, and neurodevelopmental impairment. Demonstration of autoantibodies and cytokines in some WS patients and favorable response to immunotherapy have implicated inflammation as a putative trigger of epileptiform activity in WS. Our aim was to provide additional support for altered inflammatory responses in WS through peripheral blood immunophenotype analysis.

METHODS

Eight WS cases treated with synacthen and 11 age- and sex-matched healthy volunteers were included. Peripheral blood mononuclear cells (PBMC) were isolated and immunophenotyping was performed in pre-treatment baseline (8 patients) and 3 months post-treatment (6 patients) samples. The analysis included PBMC expressing NFκB transcription and NLRP3 inflammasome factors.

RESULTS

In pre-treatment baseline samples, switched memory B cells (CD19+IgD-CD27+) were significantly reduced, whereas plasma cells (CD19+CD38+CD138+) and cytotoxic T cells (CD3+CD8+) were significantly increased. Regulatory T and B cell ratios were not significantly altered. Synacthen treatment only marginally reduced helper T cell ratios and did not significantly change other T, B, NK and NKT cell and monocyte ratios.

CONCLUSIONS

Our findings lend further support for the involvement of inflammation-related mechanisms in WS. New-onset WS patients are inclined to display increased plasma cells in the peripheral blood. Synacthen treatment does not show a beneficial effect on most effector acquired and innate immunity subsets.

CCL2/MCP-1, interleukin-8, and fractalkine/CXC3CL1: Potential biomarkers of epileptogenesis and pharmacoresistance in childhood epilepsy

OBJECTIVE

The pathophysiological processes leading to epileptogenesis and pharmacoresistance in epilepsy have been the subject of extensive preclinical and clinical research. The main impact on clinical practice is the development of new targeted therapies for epilepsy. We studied the importance of neuroinflammation in the development of epileptogenesis and pharmacoresistance in childhood epilepsy patients.

METHODS

A cross-sectional study conducted at two epilepsy centers in the Czech Republic compared 22 pharmacoresistant patients and 4 pharmacodependent patients to 9 controls. We analyzed the ProcartaPlex™ 9-Plex immunoassay panel consisting of interleukin (IL)-6, IL-8, IL-10, IL-18, CXCL10/IP-10, monocyte chemoattractant protein 1 (CCL2/MCP-1), B lymphocyte chemoattractant (BLC), tumor necrosis factor-alpha (TNF-α), and chemokine (C-X3-X motif) ligand 1 (fractalkine/CXC3CL1) to determine their alterations in cerebrospinal fluid (CSF) and blood plasma, concurrently.

RESULTS

The analysis of 21 paired CSF and plasma samples in pharmacoresistant patients compared to controls revealed a significant elevation of CCL2/MCP-1 in CSF (p < 0.000512) and plasma (p < 0.00.017). Higher levels of fractalkine/CXC3CL1 were revealed in the plasma of pharmacoresistant patients than in controls (p < 0.0704), and we determined an upward trend in CSF IL-8 levels (p < 0.08). No significant differences in CSF and plasma levels were detected between pharmacodependent patients and controls.

CONCLUSION

Elevated CCL2/MCP-1 in CSF and plasma, elevated levels of fractalkine/CXC3CL1 in CSF, and a trend toward elevated IL-8 in the CSF of patients with pharmacoresistant epilepsy indicate these cytokines as potential biomarkers of epileptogenesis and pharmacoresistance. CCL2/MCP-1was detected in blood plasma; this assessment may be easily achieved in clinical practice without the invasiveness of a spinal tap. However, due to the complexity of neuroinflammation in epilepsy, further studies are warranted to confirm our findings.

Involvement of Peripheral Monocytes with IL-1β in the Pathogenesis of West Syndrome

Neuroinflammation has been implicated in the pathogenesis of West syndrome (WS). Inflammatory cytokines, including interleukin-1β(IL-1β), have been reported to be associated with epilepsy. However, the assessment of cytokine changes in humans is not always simple or deterministic. This study aimed to elucidate the immunological mechanism of WS. We examined the intracellular cytokine profiles of peripheral blood cells collected from 13 patients with WS, using flow cytometry, and measured their serum cytokine levels. These were compared with those of 10 age-matched controls. We found that the WS group had significantly higher percentages of inter IL-1β, interleukin-1 receptor antagonist (IL-1RA)-positive monocytes, and interferon gamma (IFN-γ) in their CD8+ T cells than the control group. Interestingly, the group with sequelae revealed significantly lower levels of intracellular IFN-γ and IL-6 in their CD8+ T and CD4+ T cells, respectively, than the group without sequelae. There was no correlation between the ratios of positive cells and the serum levels of a particular cytokine in the WS patients. These cytokines in the peripheral immune cells might be involved in the neuroinflammation of WS, even in the absence of infectious or immune disease. Overall, an immunological approach using flow cytometry analysis might be useful for immunological studies of epilepsy.

Spontaneous remission of West syndrome associated with acute infection and fever in five patients

OBJECTIVE

We analyzed the records of 198 patients with West syndrome (WS) seen at a single pediatric neurology center in Argentina between June 2004 and June 2017. Five patients with infection-related spontaneous remission of the electroclinical manifestations were identified.

METHODS

The following parameters were investigated: personal and family history, clinical characteristics of the seizures - mainly spasms - and EEG findings, type of treatment, and outcome. The inclusion criteria for WS were epileptic spasms (ES) in clusters, hypsarrhythmia, and mental deterioration. Infants with ES without hypsarrhythmia and other epileptic encephalopathies with ES were excluded.

RESULTS

Five children, four boys and one girl, met the inclusion criteria of WS with spontaneous remission after a viral infection. The etiology of ES was unknown in four patients and one had a structural etiology. All patients had spontaneous remission of the ES and normalization of the EEG following acute upper respiratory infection in four and exanthema subitum in one; all of them had fever between 38.5 and 40 °C.

CONCLUSION

We report five patients with spontaneous remission of WS following acute viral infection, associated with a respiratory virus in four and exanthema subitum in one.

The role of inflammatory mediators in epilepsy: Focus on developmental and epileptic encephalopathies and therapeutic implications

In recent years, there has been an increasing interest in the potential involvement of neuroinflammation in the pathogenesis of epilepsy. Specifically, the role of innate immunity (that includes cytokines and chemokines) has been extensively investigated either in animal models of epilepsy and in clinical settings. Developmental and epileptic encephalopathies (DEE) are a heterogeneous group of epileptic disorders, in which uncontrolled epileptic activity results in cognitive, motor and behavioral impairment. By definition, epilepsy in DEE is poorly controlled by common antiepileptic drugs but may respond to alternative treatments, including steroids and immunomodulatory drugs. In this review, we will focus on how cytokines and chemokines play a role in the pathogenesis of DEE and why expanding our knowledge about the role of neuroinflammation in DEE may be crucial to develop new and effective targeted therapeutic strategies to prevent seizure recurrence and developmental regression.

Neuroinflammation in Children With Infantile Spasms: A Prospective Study Before and After Treatment With Acthar Gel (Repository Corticotropin Injection)

The selective effectiveness of adrenocorticotropic hormone (ACTH) in treating infantile spasms suggests an underlying neuroinflammation. Because neuroinflammation is mediated by activated microglia, which express translocator protein (TSPO), we imaged neuroinflammation in children with infantile spasms using positron emission tomography (PET) with ¹¹C-PK11195 (PK), which selectively binds to TSPO. Children were studied prospectively before and following treatment with Acthar Gel (repository corticotropin injection). We hypothesized that PK-PET would show neuroinflammation (increased PET uptake) in cortical and/or subcortical structures before treatment, and that this inflammation will be abolished/reduced following Acthar Gel treatment. Eight children with infantile spasms (5 males; mean age 1.8±1.1, range 0.9-4.1 years) were recruited. After clinical and video electroencephalograph (EEG) evaluation and dynamic PK-PET scan, children underwent treatment with Acthar Gel over 4 weeks, followed by repeat clinical evaluation/video-EEG 2 weeks after initiation of treatment and repeat PK-PET 2 weeks after treatment completion. Visual and quantitative analysis of PK-PET scans were performed. We calculated regional binding potential (measure of receptor-ligand binding) using a reference tissue model. Focal areas of increased PK-binding were found in the pretreatment PK-PET in 5 children. Following treatment, these increases were either reduced or normalized and were associated with cessation (n=4) or significant reduction (n=1) of spasms and complete disappearance of hypsarrhythmia. One child showed increased binding potential in basal ganglia and thalamus, despite normalization of cortical binding potential; however, these increases were likely associated with death-related causes. This study suggests Acthar Gel-responsive neuroinflammatory changes in children with infantile spasms, supporting a potential role of neuroinflammation in the pathogenesis of infantile spasms.

Spontaneous remission of infantile spasms following rotavirus gastroenteritis

Epileptic seizures might be provoked and/or exacerbated by fever or viral infection in children with epilepsy. However, this is not true for infantile spasms; in this study, we report three cases with infantile spasms became seizure free within 2-5 days following rotavirus gastroenteritis without an exchange or addition of antiepileptic drugs, and hypsarrhythmia evolved to diffuse slow waves or localized spikes on electroencephalography. We propose that the probability regarding the mechanism of spontaneous mitigation is the suppression of immunopathological processes caused by infection, while the possibility of ketogenic effects of diarrhea and intestinal flora recombination after rotavirus gastroenteritis is unlikely. Further study may provide important information concerning the mechanism of seizure control and the applicability to treatment for infantile spasms.

Spontaneous remission of West syndrome following a human herpesvirus 7 infection in a Chinese infant: A case report

RATIONALE

West syndrome (WS) is an age-dependent epileptic encephalopathy that is characterized by intractable epileptic seizures, hypsarrhythmia, and observed through electroencephalogram (EEG) and significant neurodevelopmental regression. The spontaneous remission of epileptic seizure is clinically rare and has not previously been reported in a Chinese infant. Herein, we reported a Chinese infant with WS whose seizures disappeared following a human herpesvirus 7 (HHV-7) infection.

PATIENT CONCERNS

The male Chinese infant was born at the gestational age of 36 weeks with a birth weight of 1.65 kg and an Apgar score of 7 at the first minute. At the age of 6 months, the infant developed seizures that manifested as flexor spasms with trunk involvement and mental regression.

DIAGNOSIS

Brain magnetic resonance imaging revealed leukomalacia of the posterior horn and a reduction in the size of the periventricular of the bilateral ventricle and the corpus callosum. An EEG revealed hypsarrhythmia and typical spasm seizures. Therefore, the infant was diagnosed with symptomatic WS.

INTERVENTIONS

The infant was treated with adequate vitamin B6 intravenous drip and oral treatment with topiramate and levetiracetam.

OUTCOMES

The observed seizures disappeared spontaneously 40 days after onset, without any changes in the anti-epileptic drug treatment, following a febrile rash due to a HHV-7 infection.

LESSONS

Spontaneous remission of epileptic seizures can occur following viral infection of HHV-7 in children with WS. The mechanism behind this spontaneous remission warrants further research.

Molecular Mechanism Involved in the Pathogenesis of Early-Onset Epileptic Encephalopathy

Recent studies have shown that neurologic inflammation may both precipitate and sustain seizures, suggesting that inflammation may be involved not only in epileptogenesis but also in determining the drug-resistant profile. Extensive literature data during these last years have identified a number of inflammatory markers involved in these processes of “neuroimmunoinflammation” in epilepsy, with key roles for pro-inflammatory cytokines such as: IL-6, IL-17 and IL-17 Receptor (IL-17R) axis, Tumor-Necrosis-Factor Alpha (TNF-α) and Transforming-Growth-Factor Beta (TGF-β), all responsible for the induction of processes of blood-brain barrier (BBB) disruption and inflammation of the Central Nervous System (CNS) itself. Nevertheless, many of these inflammatory biomarkers have also been implicated in the pathophysiologic process of other neurological diseases. Future studies will be needed to identify the disease-specific biomarkers in order to distinguish epilepsies from other neurological diseases, as well as recognize different epileptic semiology. In this context, biological markers of BBB disruption, as well as those reflecting its integrity, can be useful tools to determine the pathological process of a variety of neurological diseases. However; how these molecules may help in the diagnosis and prognostication of epileptic disorders remains yet to be determined. Herein, authors present an extensive literature review on the involvement of both, systemic and neuronal immune systems, in the early onset of epileptic encephalopathy.

Serial Analysis of Multiple Serum Cytokine Responses to Adrenocorticotropic Hormone Therapy in Patients With West Syndrome

Adrenocorticotropic hormone (ACTH) therapy is effective for West syndrome; however, the underlying mechanism of action remains unknown. This study explored this mechanism in 5 Japanese patients with West syndrome, injected with ACTH for 28 days. Serum samples were obtained before and 30, 120, and 720 minutes after ACTH injection divided into an "early" (1-4 days) and a "late" (10-28 days) group. Responses to ACTH over time were analyzed by measuring the levels of 27 cytokines. In the early group, serum levels of interleukins-5, -9, and -17, basic fibroblast growth factor, interferon (IFN-γ), IFN-γ-inducible protein 10, chemokine ligand (CCL) 3 and 4, and platelet-derived growth factor were higher in all patients before ACTH administration than in the 720-minute time point. In the late group, no definite trend was observed except for decreased CCL2 levels after ACTH administration. These changes may correlate with mechanisms underlying the anticonvulsant effects of ACTH.

Immunity and inflammation in status epilepticus and its sequelae: possibilities for therapeutic application

Status epilepticus (SE) is a life-threatening neurological emergency often refractory to available treatment options. It is a very heterogeneous condition in terms of clinical presentation and causes, which besides genetic, vascular and other structural causes also include CNS or severe systemic infections, sudden withdrawal from benzodiazepines or anticonvulsants and rare autoimmune etiologies. Treatment of SE is essentially based on expert opinions and antiepileptic drug treatment per se seems to have no major impact on prognosis. There is, therefore, urgent need of novel therapies that rely upon a better understanding of the basic mechanisms underlying this clinical condition. Accumulating evidence in animal models highlights that inflammation ensuing in the brain during SE may play a determinant role in ongoing seizures and their long-term detrimental consequences, independent of an infection or auto-immune cause; this evidence encourages reconsideration of the treatment flow in SE patients.

Cytotoxic edema at onset in West syndrome of unknown etiology: A longitudinal diffusion tensor imaging study

OBJECTIVE

To clarify longitudinal changes in white matter microstructures from the onset of disease in patients with West syndrome (WS) of unknown etiology.

METHODS

Diffusion tensor imaging (DTI) was prospectively performed at onset and at 12 and 24 months old in 17 children with WS of unknown etiology. DTI was analyzed using tract-based spatial statistics (TBSS) and tract-specific analysis (TSA) of 13 fiber tracts, and fractional anisotropy (FA) and mean diffusivity (MD) were compared with those of 42 age-matched controls. Correlations of FA and MD with developmental quotient (DQ) at age 24 months were analyzed. Multiple comparisons were adjusted for using the false discovery rate (q-value).

RESULTS

TBSS analysis at onset showed higher FA and lower MD in the corpus callosum and brainstem in patients. TSA showed lower MD in bilateral uncinate fasciculi (UF) (right: q < 0.001; left: q = 0.03) at onset in patients. TBSS showed a negative correlation between FA at onset and DQ in the right frontal lobe, whereas FA at 24 months old exhibited a positive correlation with DQ in the diffuse white matter. MD for bilateral UF at 24 months old on TSA correlated positively with DQ (q = 0.04, both).

SIGNIFICANCE

These findings may indicate the existence of cytotoxic edema in the immature white matter and dorsal brainstem at onset, and subsequent alterations in the diffuse white matter in WS of unknown etiology. Microstructural development in the UF might play important roles in cognitive development in WS.

[Immunological mechanism of prednisone in the treatment of infantile spasm]

OBJECTIVE

To investigate the immunological mechanism of prednisone in the treatment of infantile spasm (IS) by evaluating the immune function of IS children before and after treatment.

METHODS

Thirty children with IS were enrolled as IS group. Thirty healthy infants who underwent physical examination were enrolled as healthy control group. Fasting venous blood was collected for both groups before and after prednisone treatment. Chemiluminescence was used to measure serum levels of interleukin-1B (IL-1B), interleukin-2R (IL-2R), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α). Immunoturbidimetric assay was used to measure serum levels of immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin G (IgG). Flow cytometry was used to measure the percentages of T lymphocyte subsets (CD3⁺, CD4⁺, and CD8⁺). The clinical outcome and electroencephalographic findings were evaluated for all IS children after prednisone treatment.

RESULTS

The IS group had significantly higher serum levels of IL-2R, IL-8, and TNF-α than the healthy control group before treatment (P<0.05). The mean number of daily ictal clusters was positively correlated with the levels of IL-2R, IL-8, and TNF-α in IS children, the mean number of total daily seizures was positively correlated with IL-8 level, and any two indices out of IL-2R, IL-8, and TNF-α were positively correlated with each other (P<0.05). Among the 30 IS children treated with prednisone, 19 achieved seizure control; electroencephalography showed that 18 children achieved complete remission of hyperarrhythmia. After treatment, the IS group had significant reductions in the numbers of daily ictal clusters and total daily seizures, significant improvement in developmental quotient (P<0.05), and significant reductions in serum levels of IL-2R, L-8, and TNF-α, the percentage of CD4⁺ T lymphocytes, and CD4⁺/CD8⁺ ratio (P<0.05), as well as a significant increase in the percentage of CD8⁺ T lymphocytes (P<0.05).

CONCLUSIONS

IS children have immune dysfunction. Prednisone can control seizures in IS children, possibly by regulating and improving immune dysfunction.

Inflammation in Epileptic Encephalopathies

West syndrome (WS) is an infantile epileptic encephalopathy that manifests with infantile spasms (IS), hypsarrhythmia (in ~60% of infants), and poor neurodevelopmental outcomes. The etiologies of WS can be structural-metabolic pathologies (~60%), genetic (12%-15%), or of unknown origin. The current treatment options include hormonal treatment (adrenocorticotropic hormone and high-dose steroids) and the GABA aminotransferase inhibitor vigabatrin, while ketogenic diet can be given as add-on treatment in refractory IS. There is a need to identify new therapeutic targets and more effective treatments for WS. Theories about the role of inflammatory pathways in the pathogenesis and treatment of WS have emerged, being supported by both clinical and preclinical data from animal models of WS. Ongoing advances in genetics have revealed numerous genes involved in the pathogenesis of WS, including genes directly or indirectly involved in inflammation. Inflammatory pathways also interact with other signaling pathways implicated in WS, such as the neuroendocrine pathway. Furthermore, seizures may also activate proinflammatory pathways raising the possibility that inflammation can be a consequence of seizures and epileptogenic processes. With this targeted review, we plan to discuss the evidence pro and against the following key questions. Does activation of inflammatory pathways in the brain cause epilepsy in WS and does it contribute to the associated comorbidities and progression? Can activation of certain inflammatory pathways be a compensatory or protective event? Are there interactions between inflammation and the neuroendocrine system that contribute to the pathogenesis of WS? Does activation of brain inflammatory signaling pathways contribute to the transition of WS to Lennox-Gastaut syndrome? Are there any lead candidates or unexplored targets for future therapy development for WS targeting inflammation?

Comparison of the serum cytokine levels before and after adrenocorticotropic hormone (ACTH) therapy in patients with infantile spasm

PURPOSE

Infantile spasm is an age-dependent epileptic syndrome seen in infancy or early childhood. Although studies have investigated the epilepsy-cytokine relationship, there has been insufficient research into the relation between cytokines and infantile spasm. The purpose of this study was to examine the role of cytokines in the pathogenesis of infantile spasm by investigating cytokine levels before and 1month after adrenocorticotropic hormone (ACTH) therapy in patients diagnosed with the condition.

METHOD

Twenty patients aged between 1month and 2years and diagnosed with infantile spasm at the Karadeniz Technical University Medical Faculty Department of Child Health and Diseases Pediatric Neurology Clinic, Turkey, and 20 healthy children were included in the study. Patients received 11 doses of ACTH on 2days a week. Levels of TNF-alpha and IL-2, the main cytokines involved in inflammation and recently associated with infantile spasm, and of IL-1beta, IL-6 and IL-17A, associated with epileptic seizures, and serum levels of the IL-17A activator IL-23 were investigated in all patients at the start of treatment and 1month after completion of treatment.

RESULTS

No statistically significant difference was observed between pre- and post-treatment patient group and control group IL-1beta, IL-2, IL-23 or TNF-alpha levels. Pre-treatment IL-6 and IL-17A levels were significantly higher in the untreated patient group compared to the healthy control group (p<0.001 and p=0.002).

CONCLUSION

Our study supports the recent idea that IL-6 and IL-17A are cytokines involved in the pathogenesis of infantile spasm.

Generalized epilepsies: immunologic and inflammatory mechanisms

This article focuses on the inflammatory processes in patients with generalized epilepsies. We specifically review the data regarding West, Lennox-Gastaut, and Landau-Kleffner syndromes as they have generalized clinical or electroencephalogram features. There is substantial evidence for a pathogenic implication of immune mechanisms in these epilepsies. Animal models and abnormalities in both cellular and humoral immunity support this hypothesis. They also appear to be particularly responsive to immunomodulatory therapies, which has raised the speculation that an unbalanced immune system may play an important role in the pathophysiology of these epileptic syndromes. In this article, we discuss clinical and experimental data that support the potential implication of immune mediated inflammation and immune response in the mechanism of these entities.

Mechanisms of epileptogenesis in pediatric epileptic syndromes: Rasmussen encephalitis, infantile spasms, and febrile infection-related epilepsy syndrome (FIRES)

The mechanisms of epileptogenesis in pediatric epileptic syndromes are diverse, and may involve disturbances of neurodevelopmental trajectories, synaptic homeostasis, and cortical connectivity, which may occur during brain development, early infancy, or childhood. Although genetic or structural/metabolic factors are frequently associated with age-specific epileptic syndromes, such as infantile spasms and West syndrome, other syndromes may be determined by the effect of immunopathogenic mechanisms or energy-dependent processes in response to environmental challenges, such as infections or fever in normally-developed children during early or late childhood. Immune-mediated mechanisms have been suggested in selected pediatric epileptic syndromes in which acute and rapidly progressive encephalopathies preceded by fever and/or infections, such as febrile infection-related epilepsy syndrome, or in chronic progressive encephalopathies, such as Rasmussen encephalitis. A definite involvement of adaptive and innate immune mechanisms driven by cytotoxic CD8(+) T lymphocytes and neuroglial responses has been demonstrated in Rasmussen encephalitis, although the triggering factor of these responses remains unknown. Although the beneficial response to steroids and adrenocorticotropic hormone of infantile spasms, or preceding fever or infection in FIRES, may support a potential role of neuroinflammation as pathogenic factor, no definite demonstration of such involvement has been achieved, and genetic or metabolic factors are suspected. A major challenge for the future is discovering pathogenic mechanisms and etiological factors that facilitate the introduction of novel targets for drug intervention aimed at interfering with the disease mechanisms, therefore providing putative disease-modifying treatments in these pediatric epileptic syndromes.

Targeting inflammation as a therapeutic strategy for drug-resistant epilepsies: an update of new immune-modulating approaches

An increasing body of literature data suggests that inflammation, and in particular neuroinflammation, is involved in the pathophysiology of particular forms of epilepsy and convulsive disorders. Animal models have been used to identify inflammatory triggers in epileptogenesis and inflammation has recently been shown to enhance seizures. For example, pharmacological blockade of the IL-1beta/IL-1 receptor type 1 axis during epileptogenesis has been demonstrated to provide neuroprotection in temporal lobe epilepsy. Furthermore, experimental models have suggested that neural damage and the onset of spontaneous recurrent seizures are modulated via complex interactions between innate and adaptive immunity. However, it has also been suggested that inflammation can occur as a result of epilepsy, since animal models have also shown that seizure activity can induce neuroinflammation, and that recurrent seizures maintain chronic inflammation, thereby perpetuating seizures. On the basis of these observations, it has been suggested that immune-mediated therapeutic strategies may be beneficial for treating some drug resistant epilepsies with an underlying demonstrable inflammatory process. Although the potential mechanisms of immunotherapeutic strategies in drug-resistant seizures have been extensively discussed, evidence on the efficacy of such therapy is limited. However, recent research efforts have been directed toward utilizing the potential therapeutic benefits of anti-inflammatory agents in neurological disease and these are now considered prime candidates in the ongoing search for novel anti-epileptic drugs. The objective of our review is to highlight the immunological features of the pathogenesis of seizures and to analyze possible immunotherapeutic approaches for drug resistant epilepsies that can alter the immune-mediated pathogenesis.

Basic mechanisms of catastrophic epilepsy -- overview from animal models

Infantile spasms are age-specific seizures of infantile epileptic encephalopathies that are usually associated with poor epilepsy and neurodevelopmental outcomes. The current treatments are not always effective and may be associated with significant side effects. Various mechanisms have been proposed as pathogenic for infantile spasms, including cortical or brainstem dysfunction, disruption of normal cortical-subcortical communications, genetic defects, inflammation, stress, developmental abnormalities. Many of these have been recently tested experimentally, resulting into the emergence of several animal models of infantile spasms. The stress theory of spasms yielded the corticotropin releasing hormone (CRH)-induced model, which showed the higher proconvulsant potency of CRH in developing rats, although only limbic seizures were observed. Models of acute induction of infantile spasms in rodents include the N-methyl-d-aspartate (NMDA) model of emprosthotonic seizures, the prenatal betamethasone and prenatal stress variants of the NMDA model, and the γ-butyrolactone induced spasms in a Down's syndrome mouse model. Chronic rodent models of infantile spasms include the tetrodotoxin model and the multiple-hit models in rats, as well as two genetic mouse models of interneuronopathies with infantile spasms due to loss of function of the aristaless X-linked homeobox-related gene (ARX). This review discusses the emerging mechanisms for generation of infantile spasms and their associated chronic epileptic and dyscognitive phenotype as well as the recent progress in identifying pathways to better treat this epileptic encephalopathy.

Causes of CNS inflammation and potential targets for anticonvulsants

Inflammation is one of the most important endogenous defence mechanisms in an organism. It has been suggested that inflammation plays an important role in the pathophysiology of a number of human epilepsies and convulsive disorders, and there is clinical and experimental evidence to suggest that inflammatory processes within the CNS may either contribute to or be a consequence of epileptogenesis. This review discusses evidence from human studies on the role of inflammation in epilepsy and highlights potential new targets in the inflammatory cascade for antiepileptic drugs. A number of mechanisms have been shown to be involved in CNS inflammatory reactions. These include an inflammatory response at the level of the blood-brain barrier (BBB), immune-mediated damage to the CNS, stress-induced release of inflammatory mediators and direct neuronal dysfunction or damage as a result of inflammatory reactions. Mediators of inflammation in the CNS include interleukin (IL)-1β, tumour necrosis factor-α, nuclear factor-κB and toll-like receptor-4 (TLR4). IL-1β, BBB and high-mobility group box-1-TLR4 signalling appear to be the most promising targets for anticonvulsant agents directed at inflammation. Such agents may provide effective therapy for drug-resistant epilepsies in the future.

Cytokines in cerebrospinal fluid of children with West syndrome

In this study we aimed to determine the levels of tumor necrosis factor beta (TNF-b), interleukin (IL) 1-beta (IL-1b), IL-5, IL-10, and interferon gamma (IFN-g ) in CSF from children during the onset of West syndrome (WS). We observed elevated levels of IL-1b and IFN-g correlated to clinical, EEG, therapeutic response, and follow-up suggesting the involvement of immune response in WS. These results suggest that inflammatory and immunologic mediators may play a role in the pathophysiologic mechanisms of infantile spasms. Our findings may explain the perfusion and cognitive disfunctions and actions of adrenocorticotropic hormone (ACTH), corticosteroids, and intravenous immunoglobulin (IVIg) observed in WS. In conclusion, WS results from association of neurophysiological mechanisms and structural abnormalities with participation of cytokines mainly in symptomatic group.

Immune-mediated epilepsies

A pathogenic role of immunity in epilepsies has long been suggested based on observations of the efficacy of immune-modulating treatments and, more recently, by the finding of inflammation markers including autoantibodies in individuals with a number of epileptic disorders. Clinical and experimental data suggest that both innate and adaptive immunity may be involved in epilepsy. Innate immunity represents an immediate, nonspecific host response against pathogens via activation of resident brain immune cells and inflammatory mediators. These are hypothesized to contribute to seizures and epileptogenesis. Adaptive immunity employs activation of antigen-specific B and T lymphocytes or antibodies in the context of viral infections and autoimmune disorders. In this article we critically review the evidence for pathogenic roles of adaptive immune responses in several types of epilepsy, and discuss potential mechanisms and therapeutic targets. We highlight future directions for preclinical and clinical research that are required for improved diagnosis and treatment of immune-mediated epilepsies.

Increased level of serum interleukin-1 receptor antagonist subsequent to resolution of clinical symptoms in patients with West syndrome

The aim of this study was to evaluate whether proconvulsive interleukin-1β (IL-1β) and anticonvulsive IL-1 receptor antagonist (IL-1Ra) are markers of the effectiveness of treatment in patients with West syndrome (WS). We analyzed serum and cerebrospinal fluid (CSF) levels of IL-1β and IL-1Ra in 13 patients with WS. The serum IL-1Ra levels postimprovement (average, 384.6 pg/ml) in clinical and electroencephalographic (EEG) findings were significantly higher than the preimprovement values (average, 240.6 pg/ml). No significant difference in the preimprovement serum IL-1Ra levels was noted between the anticonvulsant (AED)-response and adrenocorticotropic hormone (ACTH)-response groups (260.0 pg/ml, n=7 vs. 218.0 pg/m, n=6) and the cryptogenic and symptomatic groups (290.1 pg/ml, n=4 vs. 218.3 pg/m, n=9), respectively; as for the preimprovement CSF levels, the AED-response group (114.5 pg/m; n=3) and ACTH-response groups (138.0 pg/m; n=6) and the cryptogenic (59.3 pg/m; n=3) and symptomatic groups (165.6 pg/m; n=6), respectively. Serum and CSF IL-1β levels were detected only in 3 patients preimprovement. Serum IL-1Ra levels were elevated subsequent to resolution of clinical and EEG findings in WS patients. A larger study should be conducted to clarify whether an immunological processes are concerned with the pathophysiology of WS.

Peripheral lymphocyte subset and serum cytokine profiles of patients with West syndrome

OBJECTIVE

To clarify the immune pathophysiology of West syndrome (WS).

STUDY DESIGN

We measured peripheral blood lymphocyte subset and serum cytokine profiles in 76 WS patients and 26 age-matched controls. Adrenocorticotropic hormone (ACTH) is one of the most effective therapy for WS and presumably immune-modulating; therefore, we compared the measured parameters between before ACTH (pre-ACTH) WS patients and controls, between cryptogenic and symptomatic WS patients before ACTH (pre-ACTH), and between before (pre-ACTH) and after (post-ACTH) ACTH WS patients. The post-ACTH group included those who received the last ACTH dose within 1 month of sampling.

RESULTS

CD3+ CD25+, CD19+, and CD19+ CD95+ cells were found to be significantly lower in the pre-ACTH group than in the controls. Interleukin (IL)-1 receptor antagonist (RA), 5, 6, and 15; eotaxin; basic fibroblast growth factor (bFGF); and interferon gamma-inducible protein (IP)-10 levels were higher in pre-ACTH group than in the controls. No significant differences were found between the pre-ACTH cryptogenic and symptomatic groups. CD4+ cells, CD3+ cells, CD4+/8+ ratio, IL-1 beta, IL-12, and macrophage inflammatory protein (MIP)-1 beta were significantly higher in pre-ACTH group than in the post-ACTH group.

CONCLUSIONS

Our study revealed immunological alterations in WS patients, and these responses were modified by ACTH therapy. Further study is needed to elucidate whether or how the immune system alteration is involved in the pathophysiology of WS.

Can fever treat epileptic encephalopathies?

PURPOSE

To describe resistant epileptic encephalopathies that significantly improved after an acute febrile episode (FE).

METHODS

We reviewed the clinical history of patients with daily pharmacoresistant seizures referred to the Saint-Vincent de Paul Hospital in the last 5 years. Four patients experienced seizure arrest in relation with a febrile episode.

RESULTS

The four patients suffered from epileptic encephalopathy. Three were symptomatic, one cryptogenic. They presented spasms and atypical absences, beginning after the age of 1 year. All seizures stopped at the onset of fever, and significant EEG improvement was observed. The seizure-free period ranged from 2 to 24 months.

DISCUSSION AND CONCLUSION

The close link between the occurrence of FE and the disappearance of seizures and EEG improvement, contrasting with the previous pharmacoresistance of this epileptic encephalopathy, supports a non fortuitous association. Several mechanisms could explain this phenomenon, including viral etiology, hyperthermia, inflammatory-immune reaction and ACTH release. Better understanding this phenomenon could open new therapeutic perspectives.

Maternal IgG suppresses NMDA-induced spasms in infant rats and inhibits NMDA-mediated neurotoxicity in hippocampal neurons

Maternal immunoglobulin G (IgG) was derived from Wistar rats that just delivered the new offsprings. We examined the effect of this maternal IgG on infantile spasms induced by N-methyl-d-aspartate (NMDA) in immature rats. Pup animals were treated subcutaneously with 10 mg/kg/day maternal IgG from day 11 to day 15 after birth followed by a single intraperitoneal dose of NMDA (15 mg/kg). Administration of maternal IgG decreased the severity and increased the number of ACTH immunoreactive cells in the cortex of rats with NMDA-induced spasms. Furthermore, maternal IgG inhibited NMDA-induced intracellular LDH activity in cultured hippocampal neurons in a dose-dependent manner. The results indicate that maternal IgG can attenuate NMDA-induced seizures. In infantile spasms, some factors may during pregnancy negatively affect the transfer of maternal IgG from mother to fetus thereby causing a decrease in the amount of protective maternal IgG.

Cerebrospinal fluid interleukin-6 levels in patients with West syndrome

Elevated cytokine response has been reported in patients with epileptic seizures. The objective of this study was to investigate the possible role of interleukin-6 (IL-6) in the pathogenesis of infantile spasms in West syndrome (WS). We measured IL-6 levels in cerebrospinal fluid (CSF) obtained from the newly diagnosed patients with WS. Twelve patients with WS (Group I) were classified as symptomatic WS (Group IA) in eight and as cryptogenic WS (Group IB) in four. The results were compared with control groups including patients with tonic-clonic seizures associated with two different kind of inflammation of central nervous system; Group IIA (infection): bacterial meningitis/encephalitis and Group IIB (trauma): post-traumatic seizures. There was no statistically significant difference between the mean values of CSF IL-6 levels in patients with WS (2.95 +/- 2.31 pg/ml) and those of subgroups of WS (Group IA: 2.26 +/- 2.01 pg/ml and Group IB: 4.33 +/- 2.52 pg/ml). Both control groups had highly increased IL-6 levels in CSF (Group IIA: 193.05 +/- 185.52 pg/ml and Group IIB: 112.74 +/- 167.44 pg/ml) than those of the patients with WS. Elevated IL-6 response in patients with tonic-clonic seizures associated with inflammation of central nervous system might be due to the seizures themselves or related to the underling etiology (infection or trauma). However, no elevated IL-6 response was found in patients with infantile spasms.

Brain inflammation in epilepsy: experimental and clinical evidence

Inflammatory reactions occur in the brain in various CNS diseases, including autoimmune, neurodegenerative, and epileptic disorders. Proinflammatory and antiinflammatory cytokines and related molecules have been described in CNS and plasma, in experimental models of seizures and in clinical cases of epilepsy. Inflammation involves both the innate and the adaptive immune systems and shares molecules and pathways also activated by systemic infection. Experimental studies in rodents show that inflammatory reactions in the brain can enhance neuronal excitability, impair cell survival, and increase the permeability of the blood-brain barrier to blood-borne molecules and cells. Moreover, some antiinflammatory treatments reduce seizures in experimental models and, in some instances, in clinical cases of epilepsy. However, inflammatory reactions in brain also can be beneficial, depending on the tissue microenvironment, the inflammatory mediators produced in injured tissue, the functional status of the target cells, and the length of time the tissue is exposed to inflammation. We provide an overview of the current knowledge in this field and attempt to bridge experimental and clinical evidence to discuss critically the possibility that inflammation may be a common factor contributing, or predisposing, to the occurrence of seizures and cell death, in various forms of epilepsy of different etiologies. The elucidation of this aspect may open new perspectives for the pharmacologic treatment of seizures.

Tumor necrosis factor-alpha inhibits seizures in mice via p75 receptors

Brain inflammatory reactions have been described in various neurological disorders, including epilepsy. Although there is clear evidence that cytokines affect neuroglial functions and blood-brain barrier permeability, scarce information is available on the functional consequences of brain inflammation on seizures. We studied the role of tumor necrosis factor-alpha (TNF)-alpha and its p55 and p75 receptors in seizure modulation. We found that intrahippocampal injection of murine recombinant TNF-alpha potently inhibits seizure in mice while human recombinant TNF-alpha, which shows strong specificity for mouse p55 receptors, was ineffective. p75 receptors were detected in mouse hippocampal neurons, whereas p55 receptors were absent. Transgenic mice with a perturbed TNF-alpha system showed profound alterations in seizure susceptibility: astrocytic overexpression of TNF-alpha was associated with reduced seizures, whereas mice lacking TNF-alpha p75 or both p55 and p75, receptors showed prolonged seizures. Mice deficient in p55 receptor only showed reduced seizures; and both p75 and TNF receptor-associated factor 2 protein levels were upregulated in their hippocampi. Our findings show that increased brain levels of TNF-alpha result in significant inhibition of seizures in mice, and this action is mediated by neuronal p75 receptors. This evidence highlights a novel function of TNF-alpha in brain and indicates a new system for anticonvulsive intervention.

Inflammation and epilepsy

In recent years, increasing evidence has indicated that immune and inflammatory reactions occur in brain in various central nervous system (CNS) diseases. Furthermore, inflammatory processes, such as the production of proinflammatory cytokines and related molecules, have been described in brain after seizures induced in experimental models and in clinical cases of epilepsy. Although little is known about the role of inflammation in epilepsy, it has been hypothesized that activation of the innate immune system and associated inflammatory reactions in brain may mediate some of the molecular and structural changes occurring during and after seizure activity. Whether the innate immune response that takes place in epileptic tissue is beneficial or noxious to the CNS is still an open and intriguing question that should be addressed by further investigations.

Epilepsy and the immune system: is there a link?

The concept that the immune system plays a role in the epileptogenic process of some epileptic syndromes was first proposed more than 20 years ago. Since then, numerous studies have reported on the existence of a variety of immunological alterations in epileptic patients, on the observation of favourable responses of refractory epilepsy syndromes to immunomodulatory treatment, and on the association of certain well-known immune-mediated disease states with epilepsy. This review comprehensively recapitulates the currently available evidence supporting or arguing against the possible involvement of the immune system in the pathogenesis of certain types of epilepsy. It is concluded that an abundance of facts is in support of this concept and that further studies should be directed at substantiating the pathogenic significance of (auto)immune responses in certain types of epilepsy. Current progress in the functional and molecular immunological research techniques will indisputably contribute to the elucidation of this link.

Immunologic aspects of West syndrome and evidence of plasma inhibitory effects on T cell function

STUDY OBJECTIVE: The purpose of this study was to assess the extent of immune dysfunction in a well-defined group of epileptic patients: children with diagnosis of West syndrome (WS) or with transitions to another age-related EEG patterns, the multifocal independent spikes (MIS), and the slow spike-wave complexes (Lennox-Gastaut syndrome - LGS). Thus, WS was studied at different points of the natural evolutive history of the disease. METHOD: A group of 50 patients (33 with WS, 10 with LGS and 7 with MIS) and 20 age-matched healthy controls were submitted to enumeration of T lymphocyte subsets: CD1, CD3, CD4, CD8, CD4/CD8 ratio and lymphocyte proliferation assay to phytohaemagglutinin (PHA), in the presence of autologous and AB, homologous plasma. Dinitrochlorobenzene (DNCB) skin test sensitization was performed only in patients. Determinations of IgG, IgA, and IgM serum levels were compared to standard values for Brazilian population in different age ranges. RESULTS: Sensitization to DNCB showed absent or low skin reactions in 76% of the patients. High levels of IgG (45.7%) and IgM (61.4%), and lower levels of IgA (23.9%) were detected in the serum of the patients. Enumeration of lymphocyte subsets in peripheral blood showed: low CD3+ (p<0.05), low CD4+ (p<0.05), high CD8+ (p<0.01) and low CD4+ / CD8+ ratio (p<0.001). The proportion of CD1+ cells in the control group was less than 3%, while ranged between 6 and 11 % in 18% of the patients. The in vitro PHA-induced T cell proliferation showed significantly low blastogenic indices only when patients, cells were cultured in presence of their own plasma. No differences in blastogenic indices were observed when the cells of patients and controls were cultured with human AB plasma. CONCLUSION: The immunodeficiency in WS was mainly characterized by anergy, impaired cell-mediated immunity, altered levels of immunoglobulins, presence of immature thymocytes in peripheral blood and functional impairment of T lymphocytes induced by plasma inhibitory factors.