A role for leukocyte-endothelial adhesion mechanisms in epilepsy

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?

Cellular responses to recurrent pentylenetetrazole-induced seizures in the adult zebrafish brain

A seizure is a sustained increase in brain electrical activity that can result in loss of consciousness and injury. Understanding how the brain responds to seizures is important for development of new treatment strategies for epilepsy, a neurological condition characterized by recurrent and unprovoked seizures. Pharmacological induction of seizures in rodent models results in a myriad of cellular alterations, including inflammation, angiogenesis, and adult neurogenesis. The purpose of this study is to investigate the cellular responses to recurrent pentylenetetrazole seizures in the adult zebrafish brain. We subjected zebrafish to five once-daily pentylenetetrazole-induced seizures and characterized the cellular consequences of these seizures. In response to recurrent seizures, we found histologic evidence of vasodilatation, perivascular leukocyte egress and leukocyte proliferation suggesting seizure-induced acute CNS inflammation. We also found evidence of increased proliferation, neurogenesis, and reactive gliosis following pentylenetetrazole-induced seizures. Collectively, our results suggest that the cellular responses to seizures in the adult zebrafish brain are similar to those observed in mammalian brains.

Cerebrospinal fluid analysis after unprovoked first seizure

The aim of this study was to determine cerebrospinal fluid (CSF) characteristics after an unprovoked first seizure (UFS). We reviewed the medical records of 71 patients with UFS who underwent lumbar puncture, and examined the CSF parameters. Each CSF parameter was evaluated separately for potential correlations with the other study variables. We observed an overall frequency of CSF abnormalities of 35.2%. CSF protein was the most common abnormal parameter (31%) and showed significant positive correlations with male gender (p=0.037) and older age (p=0.007). Only seven patients (9.9%) had an abnormal cell count (5-40 cells/μl). Higher CSF cell counts were found to predict a longer hospitalization period (p=0.005). No relationship with abnormal EEG findings could be established (p=0.169). This study is one of the few to evaluate postictal CSF parameters in a clinical setting, and to our knowledge the first to investigate these parameters specifically in the emergency department. The development of a rapid, easy-to-use test that does not require extensive laboratory equipment to differentiate UFS from other conditions could be of great value in everyday clinical practice.

Intranasal Delivery of miR-146a Mimics Delayed Seizure Onset in the Lithium-Pilocarpine Mouse Model

Unveiling the key mechanism of temporal lobe epilepsy (TLE) for the development of novel treatments is of increasing interest, and anti-inflammatory miR-146a is now considered a promising molecular target for TLE. In the current study, a C57BL/6 TLE mouse model was established using the lithium-pilocarpine protocol. The seizure degree was evaluated according to the Racine scale, and level 5 was considered the threshold for generalized convulsions. Animals were sacrificed to analyze the hippocampus at three time points (2 h and 4 and 8 weeks after pilocarpine administration to evaluate the acute, latent, and chronic phases, resp.). After intranasal delivery of miR-146a mimics (30 min before pilocarpine injection), the percent of animals with no induced seizures increased by 6.7%, the latency to generalized convulsions was extended, and seizure severity was reduced. Additionally, hippocampal damage was alleviated. While the relative miR-146a levels significantly increased, the expression of its target mRNAs (IRAK-1 and TRAF-6) and typical inflammatory modulators (NF-κB, TNF-α, IL-1β, and IL-6) decreased, supporting an anti-inflammatory role of miR-146a via the TLR pathway. This study is the first to demonstrate that intranasal delivery of miR-146a mimics can improve seizure onset and hippocampal damage in the acute phase of lithium-pilocarpine-induced seizures, which provides inflammation-based clues for the development of novel TLE treatments.

Immune-to-Brain Communication Pathways in Inflammation-Associated Sickness and Depression

A growing body of evidence now highlights a key role for inflammation in mediating sickness behaviors and depression. Systemic inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, and chronic liver disease have high comorbidity with depression. How the periphery communicates with the brain to mediate changes in neurotransmission and thereby behavior is not completely understood. Traditional routes of communication between the periphery and the brain involve neural and humoral pathways with TNFα, IL-1β, and IL-6 being the three main cytokines that have primarily been implicated in mediating signaling via these pathways. However, in recent years communication via peripheral immune-cell-to-brain and the gut-microbiota-to-brain routes have received increasing attention for their ability to modulate brain function. In this chapter we discuss periphery-to-brain communication pathways and their potential role in mediating inflammation-associated sickness behaviors and depression.

Matrix Metalloproteinase 9 in Epilepsy: The Role of Neuroinflammation in Seizure Development

Matrix metalloproteinase 9 is a proteolytic enzyme which is recently one of the more often studied biomarkers. Its possible use as a biomarker of neuronal damage in stroke, heart diseases, tumors, multiple sclerosis, and epilepsy is being widely indicated. In epilepsy, MMP-9 is suggested to play a role in epileptic focus formation and in the stimulation of seizures. The increase of MMP-9 activity in the epileptic focus was observed both in animal models and in clinical studies. MMP-9 contributes to formation of epileptic focus, for example, by remodeling of synapses. Its proteolytic action on the elements of blood-brain barrier and activation of chemotactic processes facilitates accumulation of inflammatory cells and induces seizures. Also modification of glutamatergic transmission by MMP-9 is associated with seizures. In this review we will try to recapitulate the results of previous studies about MMP-9 in terms of its association with epilepsy. We will discuss the mechanisms of its actions and present the results revealed in animal models and clinical studies. We will also provide a comparison of the results of various studies on MMP-9 levels in the context of its possible use as a biomarker of the activity of epilepsy.

Magnesium Sulfate Provides Neuroprotection in Eclampsia-Like Seizure Model by Ameliorating Neuroinflammation and Brain Edema

Eclampsia is a hypertensive disorder of pregnancy that is defined by the new onset of grand mal seizures on the basis of preeclampsia and a leading cause of maternal and fetal mortality worldwide. Presently, magnesium sulfate (MgSO₄) is the most effective treatment, but the mechanism by which MgSO₄ prevents eclampsia has yet to be fully elucidated. We previously showed that systemic inflammation decreases the seizure threshold in a rat eclampsia-like model, and MgSO₄ treatment can decrease systemic inflammation. Here, we hypothesized that MgSO₄ plays a neuroprotective role in eclampsia by reducing neuroinflammation and brain edema. Pregnant Sprague-Dawley rats were given an intraperitoneal injection of pentylenetetrazol following a tail vein injection of lipopolysaccharide to establish the eclampsia-like seizure model. Seizure activity was assessed by behavioral testing. Neuronal loss in the hippocampal CA1 region (CA1) was detected by Nissl staining. Cerebrospinal fluid levels of S100-B and ferritin, indicators of neuroinflammation, were detected by enzyme-linked immunosorbent assay, and ionized calcium binder adapter molecule 1 (Iba-1, a marker for microglia) and glial fibrillary acid protein (GFAP, a marker for astrocytes) expression in the CA1 area was determined by immunofluorescence staining. Brain edema was measured. Our results revealed that MgSO₄ effectively attenuated seizure severity and CA1 neuronal loss. In addition, MgSO₄ significantly reduced cerebrospinal fluid levels of S100-B and ferritin, Iba-1 and GFAP activation in the CA1 area, and brain edema. Our results indicate that MgSO₄ plays a neuroprotective role against eclampsia-like seizure by reducing neuroinflammation and brain edema.

Inflammation and endothelium response in epileptic patients: A case-control study

BACKGROUND

Blood brain barrier (BBB) permeability plays an important role in the brain impairments. The barrier is composed of endothelium cells, due to the presence of tight junctions that connect endothelium cells. The failure of BBB function has triggering chronic or acute seizures through brain inflammation and BBB permeability. Seizure induces vasodilation, BBB leakage and up-regulation of vascular cell adhesion molecules which able to bind integrins blood leukocytes.

MATERIALS AND METHODS

In this case-control study we included 40 epileptic patients who were sampled during a seizure as a case group and 20 healthy subjects as a healthy control group. Plasma levels of the inflammation and endothelium markers including intercellular adhesion molecule (ICAM), vascular adhesion molecule (VCAM), interleukin 1 beta (IL-1β) and C-reactive protein (CRP) were measured by enzyme-linked immunosorbent assays (ELISAs).

RESULTS

The ICAM and VCAM concentration in the epileptic patients (135.8 ± 5.35) (52.04 ± 4.24) were significantly higher than healthy control group (110.32 ± 5.04) (23.38 ± 3.01) (P < 0.005). IL-1 beta concentration was not significantly different between groups (P = 0.594). However, CRP level was significantly up-regulated in epileptic patients (P < 0.005).

CONCLUSION

Epileptic patients have BBB leakage and dysfunction as the up-regulation of the endothelium cytokines showed. The BBB leakage may be the result of the inflammatory impairment.

The Chemokine CCL2 Mediates the Seizure-enhancing Effects of Systemic Inflammation

Epilepsy is a chronic disorder characterized by spontaneous recurrent seizures. Brain inflammation is increasingly recognized as a critical factor for seizure precipitation, but the molecular mediators of such proconvulsant effects are only partly understood. The chemokine CCL2 is one of the most elevated inflammatory mediators in patients with pharmacoresistent epilepsy, but its contribution to seizure generation remains unexplored. Here, we show, for the first time, a crucial role for CCL2 and its receptor CCR2 in seizure control. We imposed a systemic inflammatory challenge via lipopolysaccharide (LPS) administration in mice with mesial temporal lobe epilepsy. We found that LPS dramatically increased seizure frequency and upregulated the expression of many inflammatory proteins, including CCL2. To test the proconvulsant role of CCL2, we administered systemically either a CCL2 transcription inhibitor (bindarit) or a selective antagonist of the CCR2 receptor (RS102895). We found that interference with CCL2 signaling potently suppressed LPS-induced seizures. Intracerebral administration of anti-CCL2 antibodies also abrogated LPS-mediated seizure enhancement in chronically epileptic animals. Our results reveal that CCL2 is a key mediator in the molecular pathways that link peripheral inflammation with neuronal hyperexcitability.

SIGNIFICANCE STATEMENT

Substantial evidence points to a role for inflammation in epilepsy, but currently there is little insight as to how inflammatory pathways impact on seizure generation. Here, we examine the molecular mediators linking peripheral inflammation with seizure susceptibility in mice with mesial temporal lobe epilepsy. We show that a systemic inflammatory challenge via lipopolysaccharide administration potently enhances seizure frequency and upregulates the expression of the chemokine CCL2. Remarkably, selective pharmacological interference with CCL2 or its receptor CCR2 suppresses lipopolysaccharide-induced seizure enhancement. Thus, CCL2/CCR2 signaling plays a key role in linking systemic inflammation with seizure susceptibility.

Current Evidence for a Role of the Kynurenine Pathway of Tryptophan Metabolism in Multiple Sclerosis

The kynurenine pathway (KP) is the major metabolic pathway of the essential amino acid tryptophan (TRP). Stimulation by inflammatory molecules, such as interferon-γ (IFN-γ), is the trigger for induction of the KP, driving a complex cascade of production of both neuroprotective and neurotoxic metabolites, and in turn, regulation of the immune response and responses of brain cells to the KP metabolites. Consequently, substantial evidence has accumulated over the past couple of decades that dysregulation of the KP and the production of neurotoxic metabolites are associated with many neuroinflammatory and neurodegenerative diseases, including Parkinson’s disease, AIDS-related dementia, motor neurone disease, schizophrenia, Huntington’s disease, and brain cancers. In the past decade, evidence of the link between the KP and multiple sclerosis (MS) has rapidly grown and has implicated the KP in MS pathogenesis. KP enzymes, indoleamine 2,3-dioxygenase (IDO-1) and tryptophan dioxygenase (highest expression in hepatic cells), are the principal enzymes triggering activation of the KP to produce kynurenine from TRP. This is in preference to other routes such as serotonin and melatonin production. In neurological disease, degradation of the blood–brain barrier, even if transient, allows the entry of blood monocytes into the brain parenchyma. Similar to microglia and macrophages, these cells are highly responsive to IFN-γ, which upregulates the expression of enzymes, including IDO-1, producing neurotoxic KP metabolites such as quinolinic acid. These metabolites circulate systemically or are released locally in the brain and can contribute to the excitotoxic death of oligodendrocytes and neurons in neurological disease principally by virtue of their agonist activity at N-methyl-d-aspartic acid receptors. The latest evidence is presented and discussed. The enzymes that control the checkpoints in the KP represent an attractive therapeutic target, and consequently several KP inhibitors are currently in clinical trials for other neurological diseases, and hence may make suitable candidates for MS patients. Underpinning these drug discovery endeavors, in recent years, several advances have been made in how KP metabolites are assayed in various biological fluids, and tremendous advancements have been made in how specimens are imaged to determine disease progression and involvement of various cell types and molecules in MS.

Patterns of postictal cerebral perfusion in idiopathic generalized epilepsy: a multi-delay multi-parametric arterial spin labelling perfusion MRI study

The cerebral haemodynamic status of idiopathic generalized epilepsy (IGE) is a very complicated process. Little attention has been paid to cerebral blood flow (CBF) alterations in IGE detected by arterial spin labelling (ASL) perfusion magnetic resonance imaging (MRI). However, the selection of an optimal delay time is difficult for single-delay ASL. Multi-delay multi-parametric ASL perfusion MRI overcomes the limitations of single-delay ASL. We applied multi-delay multi-parametric ASL perfusion MRI to investigate the patterns of postictal cerebral perfusion in IGE patients with absence seizures. A total of 21 IGE patients with absence seizures and 24 healthy control subjects were enrolled. IGE patients exhibited prolonged arterial transit time (ATT) in the left superior temporal gyrus. The mean CBF of IGE patients was significantly increased in the left middle temporal gyrus, left parahippocampal gyrus and left fusiform gyrus. Prolonged ATT in the left superior temporal gyrus was negatively correlated with the age at onset in IGE patients. This study demonstrated that cortical dysfunction in the temporal lobe and fusiform gyrus may be related to epileptic activity in IGE patients with absence seizures. This information can play an important role in elucidating the pathophysiological mechanism of IGE from a cerebral haemodynamic perspective.

Purinergic signaling in epilepsy

Until recently, analysis of the mechanisms underlying epilepsy was centered on neuron dysfunctions. Accordingly, most of the available pharmacological treatments aim at reducing neuronal excitation or at potentiating neuronal inhibition. These therapeutic options can lead to obvious secondary effects, and, moreover, seizures cannot be controlled by any known medication in one-third of the patients. A purely neurocentric view of brain functions and dysfunctions has been seriously questioned during the past 2 decades because of the accumulation of experimental data showing the functional importance of reciprocal interactions between glial cells and neurons. In the case of epilepsy, our current knowledge of the human disease and analysis of animal models clearly favor the involvement of astrocytes and microglial cells during the progression of the disease, including at very early stages, opening the way to the identification of new therapeutic targets. Purinergic signaling is a fundamental feature of neuron-glia interactions, and increasing evidence indicates that modifications of this pathway contribute to the functional remodeling of the epileptic brain. This Review discusses the recent experimental results indicating the roles of astrocytic and microglial P2X and P2Y receptors in epilepsy. © 2016 Wiley Periodicals, Inc.

Changes in serum albumin levels and neutrophil-lymphocyte ratio in patients with convulsive status epilepticus

AIM

Inflammation may be involved in the ictogenesis and development of some partial epilepsies. Serum albumin levels and the neutrophil-lymphocyte ratio (NLR) are markers of inflammation. The aim of this study was to investigate the ability of serum albumin levels and NLR to predict inflammation in patients with convulsive status epilepticus (CSE).

METHODS

This retrospective study was conducted on 58 patients who were diagnosed with CSE and control group comprised of 58 healthy individuals. Albumin levels and NLR were evaluated during both the acute and subacute periods of CSE.

RESULTS

The average serum albumin levels were 3.27 ± 0.62 g/dL during the acute period and 3.4 ± 0.67 g/dL in the subacute period in the patient group and 3.92 ± 0.52 g/dL in the control group. Neutrophil counts were higher in patients in the acute phase of CSE, but lymphocyte counts were lower compared to the control group and the subacute phase. The average NLR values were 4.83 ± 5.1 in the acute period, 3.07 ± 3.02 during the subacute period and 1.98 ± 0.42 in the control group. Serum albumin and NLR levels were significantly different between the patients in the subacute and acute periods of CSE and the control group (p < 0.05). There were significant negative correlational relationships between serum albumin and NLR levels (p < 0.05).

CONCLUSION

We found serum albumin levels were significantly lower and the NLR was significantly higher in the acute period of CSE. Neutrophil-mediated inflammation may be important in the aetiopathogenesis of CSE.

Independent impact of infections on the course and outcome of status epilepticus: a 10-year cohort study

Infections are frequent in patients with status epilepticus (SE). It remains unclear if infections merely reflect severity of the underlying illness or if they independently predict unfavourable course and outcome. We sought to determine if infections diagnosed within 48 h from SE onset are independent predictors of poor course and outcome and if their effect is modified by clinical characteristics. From 2005 to 2014, pertinent clinical data, microbiology, death, return to functional baseline, and unfavourable outcome in survivors were assessed in SE patients treated in the intensive care units (ICU) of an academic medical care center. Among 352 consecutive patients, 81 (23 %) were diagnosed with infections at SE onset. In-hospital mortality was higher in patients with infections (26 %) compared to 10 % in patients without infections (p < 0.001). Infections at SE onset increased the odds ratios (OR) for prolonged ICU (OR = 4.1, 95 %CI 1.87-6.74) and hospital stay (OR = 5.4, 95 %CI 1.24-9.63), refractory SE (OR = 3.1, 95 %CI 1.79-5.34), prolonged mechanical ventilation (OR = 3.8, 95 %CI 2.15-6.79), no return to functional baseline (OR = 2.1, 95 %CI 1.10-4.02), unfavourable outcome in survivors (OR = 2.0, 95 %CI 1.02-3.81), and death (OR = 2.5, 95 %CI 1.28-4.99). All associations were independent of confounders and without significant effect modification by age, level of consciousness, types and severity of SE, and etiologies. In addition, the number of infections increased the probability of unfavourable course and outcome. Infections at SE onset are frequent and associated with prolonged medical care, treatment refractory SE, higher morbidity and mortality independently of potential confounders calling for the evaluation of treatment strategies.

Migration of bone marrow progenitor cells in the adult brain of rats and rabbits

Neurogenesis takes place in the adult mammalian brain in three areas: Subgranular zone of the dentate gyrus (DG); subventricular zone of the lateral ventricle; olfactory bulb. Different molecular markers can be used to characterize the cells involved in adult neurogenesis. It has been recently suggested that a population of bone marrow (BM) progenitor cells may migrate to the brain and differentiate into neuronal lineage. To explore this hypothesis, we injected recombinant SV40-derived vectors into the BM and followed the potential migration of the transduced cells. Long-term BM-directed gene transfer using recombinant SV40-derived vectors leads to expression of the genes delivered to the BM firstly in circulating cells, then after several months in mature neurons and microglial cells, and thus without central nervous system (CNS) lesion. Most of transgene-expressing cells expressed NeuN, a marker of mature neurons. Thus, BM-derived cells may function as progenitors of CNS cells in adult animals. The mechanism by which the cells from the BM come to be neurons remains to be determined. Although the observed gradual increase in transgene-expressing neurons over 16 mo suggests that the pathway involved differentiation of BM-resident cells into neurons, cell fusion as the principal route cannot be totally ruled out. Additional studies using similar viral vectors showed that BM-derived progenitor cells migrating in the CNS express markers of neuronal precursors or immature neurons. Transgene-positive cells were found in the subgranular zone of the DG of the hippocampus 16 mo after intramarrow injection of the vector. In addition to cells expressing markers of mature neurons, transgene-positive cells were also positive for nestin and doublecortin, molecules expressed by developing neuronal cells. These cells were actively proliferating, as shown by short term BrdU incorporation studies. Inducing seizures by using kainic acid increased the number of BM progenitor cells transduced by SV40 vectors migrating to the hippocampus, and these cells were seen at earlier time points in the DG. We show that the cell membrane chemokine receptor, CCR5, and its ligands, enhance CNS inflammation and seizure activity in a model of neuronal excitotoxicity. SV40-based gene delivery of RNAi targeting CCR5 to the BM results in downregulating CCR5 in circulating cells, suggesting that CCR5 plays an important role in regulating traffic of BM-derived cells into the CNS, both in the basal state and in response to injury. Furthermore, reduction in CCR5 expression in circulating cells provides profound neuroprotection from excitotoxic neuronal injury, reduces neuroinflammation, and increases neuronal regeneration following this type of insult. These results suggest that BM-derived, transgene-expressing, cells can migrate to the brain and that they become neurons, at least in part, by differentiating into neuron precursors and subsequently developing into mature neurons.

Leukocyte Infiltration Triggers Seizure Recurrence in a Rat Model of Temporal Lobe Epilepsy

Epilepsy, which affects about 1 % of the population worldwide, leads to poor prognosis and increased morbidity. However, effective drugs providing satisfactory control on seizure relapse were rare, which encouraged more etiological studies. Whether inflammation is one of key events underlying seizure is in debate. In order to explore the role of inflammatory in the pathogenesis and development of epilepsy, we conducted intra-caudal vein injection of leukocytes to aggravated brain inflammatory process in kainic acid-induced seizure model in this study. The results showed that intravenous administration of activated leukocytes increased the frequency and reduced the latent phase of seizure recurrences in rat models of epileptic seizure, during which leukocyte inflammation, brain-blood barrier damage, and neuron injury were also significantly aggravated, indicating that leukocyte infiltration might facilitate seizure recurrence through aggravating brain inflammation, brain-blood barrier damage, and neuron injury.

Proteomic profiling of epileptogenesis in a rat model: Focus on inflammation

Detailed knowledge about the patterns of molecular alterations during epileptogenesis is a presupposition for identifying targets for preventive or disease-modifying approaches, as well as biomarkers of the disease. Large-scale differential proteome analysis can provide unique and novel perspectives based on comprehensive data sets informing about the complex regulation patterns in the disease proteome. Thus, we have completed an elaborate differential proteome analysis based on label-free LC-MS/MS in a rat model of epileptogenesis. Hippocampus and parahippocampal cortex tissues were sampled and analyzed separately at three key time points chosen for monitoring disease development following electrically-induced status epilepticus, namely, the early post-insult phase, the latency phase, and the chronic phase with spontaneous recurrent seizures. We focused the bioinformatics analysis on proteins linked to immune and inflammatory responses, because of the emerging evidence of the specific pathogenic role of inflammatory signalings during epileptogenesis. In the early post-insult and the latency phases, pathway enrichment analysis revealed an extensive over-representation of Toll-like receptor signaling, pro-inflammatory cytokines, heat shock protein regulation, and transforming growth factor beta signaling and leukocyte transendothelial migration. The inflammatory response in the chronic phase proved to be more moderate with differential expression in the parahippocampal cortex exceeding that in the hippocampus. The data sets provide novel information about numerous differentially expressed proteins, which serve as interaction partners or modulators in key disease-associated inflammatory signaling events. Noteworthy, a set of proteins which act as modulators of the ictogenic Toll-like receptor signaling proved to be differentially expressed. In addition, we report novel data demonstrating the regulation of different Toll-like receptor ligands during epileptogenesis. Taken together, the findings deepen our understanding of modulation of inflammatory signaling during epileptogenesis providing an excellent and comprehensive basis for the identification of target and biomarker candidates.

Imaging of Leukocyte Trafficking in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder and is characterized by a progressive decline of cognitive functions. The neuropathological features of AD include amyloid beta (Aβ) deposition, intracellular neurofibrillary tangles derived from the cytoskeletal hyperphosphorylated tau protein, amyloid angiopathy, the loss of synapses, and neuronal degeneration. In the last decade, inflammation has emerged as a key feature of AD, but most studies have focused on the role of microglia-driven neuroinflammation mechanisms. A dysfunctional blood-brain barrier has also been implicated in the pathogenesis of AD, and several studies have demonstrated that the vascular deposition of Aβ induces the expression of adhesion molecules and alters the expression of tight junction proteins, potentially facilitating the transmigration of circulating leukocytes. Two-photon laser scanning microscopy (TPLSM) has become an indispensable tool to dissect the molecular mechanisms controlling leukocyte trafficking in the central nervous system (CNS). Recent TPLSM studies have shown that vascular deposition of Aβ in the CNS promotes intraluminal neutrophil adhesion and crawling on the brain endothelium and also that neutrophils extravasate in the parenchyma preferentially in areas with Aβ deposits. These studies have also highlighted a role for LFA-1 integrin in neutrophil accumulation in the CNS of AD-like disease models, revealing that LFA-1 inhibition reduces the corresponding cognitive deficit and AD neuropathology. In this article, we consider how current imaging techniques can help to unravel new inflammation mechanisms in the pathogenesis of AD and identify novel therapeutic strategies to treat the disease by interfering with leukocyte trafficking mechanisms.

Immunity and Inflammation in Epilepsy

This review reports the available evidence on the activation of the innate and adaptive branches of the immune system and the related inflammatory processes in epileptic disorders and the putative pathogenic role of inflammatory processes developing in the brain, as indicated by evidence from experimental and clinical research. Indeed, there is increasing knowledge supporting a role of specific inflammatory mediators and immune cells in the generation and recurrence of epileptic seizures, as well as in the associated neuropathology and comorbidities. Major challenges in this field remain: a better understanding of the key inflammatory pathogenic pathways activated in chronic epilepsy and during epileptogenesis, and how to counteract them efficiently without altering the homeostatic tissue repair function of inflammation. The relevance of this information for developing novel therapies will be highlighted.

Are they in or out? The elusive interaction between Qtracker®800 vascular labels and brain endothelial cells

Aim: Qtracker®800 Vascular labels (Qtracker®800) are promising biomedical tools for high-resolution vasculature imaging; their effects on mouse and human endothelia, however, are still unknown. Materials & methods: Qtracker®800 were injected in Balb/c mice, and brain endothelium uptake was investigated by transmission electron microscopy 3-h post injection. We then investigated, in vitro, the effects of Qtracker®800 exposure on mouse and human endothelial cells by calcium imaging. Results: Transmission electron microscopy images showed nanoparticle accumulation in mouse brain endothelia. A subset of mouse and human endothelial cells generated intracellular calcium transients in response to Qtracker®800. Conclusion: Qtracker®800 nanoparticles elicit endothelial functional responses, which prompts biomedical safety evaluations and may bias the interpretation of experimental studies involving vascular imaging.

Role of inflammation and its miRNA based regulation in epilepsy: Implications for therapy

There is a need to develop innovative therapeutic strategies to counteract epilepsy, a common disabling neurological disorder. Despite the recent advent of additional antiepileptic drugs and respective surgery, the treatment of epilepsy remains a major challenge. The available therapies are largely based on symptoms, and these approaches do not affect the underlying disease processes and are also associated frequently with severe side effects. This is mainly because of the lack of well-defined targets in epilepsy. The discovery that inflammatory mediators significantly contribute to the onset and recurrence of seizures in experimental seizure models, as well as the presence of inflammatory molecules in human epileptogenic tissue, highlights the possibility of targeting specific inflammation related pathways to control seizures that are otherwise resistant to the available AEDs. Emerging studies suggest that miRNAs have a significant role in regulating inflammatory pathways shown to be involved in epilepsy. These miRNAs can possibly be used as novel therapeutic targets in the treatment of epilepsy as well as serve as diagnostic biomarkers of epileptogenesis. This review highlights the immunological features underlying the pathogenesis of epileptic seizures and the possible miRNA mediated approaches for drug resistant epilepsies that modulate the immune-mediated pathogenesis.

Procalcitonin and mortality in status epilepticus: an observational cohort study

INTRODUCTION

Acute-phase proteins, such as procalcitonin (PCT), C-reactive protein (CRP) and albumin, may relate with course and outcome in status epilepticus (SE), as seizures bring about inflammation, changes of cytokine levels and blood-brain barrier breakdown. We aimed to determine the predictive value of serum levels of PCT at SE onset for the emergence of infections and unfavorable outcome in adult patients with SE. Furthermore, we sought to compare the predictive value of PCT, CRP and albumin for death.

METHODS

This observational cohort study was performed in the intensive care units of the University Hospital Basel (Switzerland), a university-affiliated tertiary care center. Adult patients with SE admitted from 2005 to 2012 were included. Serum levels of PCT, CRP and albumin were assessed at SE onset. Unfavorable outcome (i.e., death and a Glasgow Outcome Score of 1 to 3) during hospital stay and mortality after 30 days were considered the primary and infections as the secondary outcome measures.

RESULTS

In 91 SE patients, mortality was 23.1 % during hospital stay and at 30-days follow-up. Infections emerged in 30.8 % of patients. In the multivariable analysis, PCT predicted unfavorable outcome independently from possible confounders such as acute etiology, infections during SE, the Charlson Comorbidity Index, and the Status Epilepticus Severity Score (hazard ratio 1.44 per every increasing ug/L, 95 % confidence interval 1.11-1.87). Additional multivariable analysis including serum levels of PCT, CRP and albumin revealed PCT as the only biomarker independently associated with an increased hazard for unfavorable outcome. PCT levels at SE onset were not related to infections during SE.

CONCLUSIONS

Serum PCT levels measured at SE onset are independently associated with unfavorable outcome but do not predict the emergence of infections during SE. Procalcitonin may increase the predictive value of clinical scoring systems allowing for rapid risk stratification early in the course of SE.

Myeloperoxidase Nuclear Imaging for Epileptogenesis

PURPOSE

To determine if myeloperoxidase (MPO) is involved in epileptogenesis and if molecular nuclear imaging can be used to noninvasively map inflammatory changes in epileptogenesis.

MATERIALS AND METHODS

The animal and human studies were approved by the institutional review boards. Pilocarpine-induced epileptic mice were treated with 4-aminobenzoic acid hydrazide (n = 46), a specific irreversible MPO inhibitor, or saline (n = 42). Indium-111-bis-5-hydroxytryptamide-diethylenetriaminepentaacetate was used to image brain MPO activity (n = 6 in the 4-aminobenzoic acid hydrazide and saline groups; n = 5 in the sham group) by using single photon emission computed tomography/computed tomography. The role of MPO in the development of spontaneous recurrent seizures was assessed by means of clinical symptoms and biochemical and histopathologic data. Human brain specimens from a patient with epilepsy and a patient without epilepsy were stained for MPO. The Student t test, one-way analysis of variance, and Mann-Whitney and Kruskal-Wallis tests were used. Differences were regarded as significant if P was less than .05.

RESULTS

MPO and leukocytes increased in the brain during epileptogenesis (P < .05). Blocking MPO delayed spontaneous recurrent seizures (99.6 vs 142 hours, P = .016), ameliorated the severity of spontaneous recurrent seizures (P < .05), and inhibited mossy fiber sprouting (Timm index, 0.31 vs 0.03; P = .003). Matrix metalloproteinase activity was upregulated during epileptogenesis in an MPO-dependent manner (1.44 vs 0.94 U/mg, P = .049), suggesting that MPO acts upstream of matrix metalloproteinases. MPO activity was mapped during epileptogenesis in vivo in the hippocampal regions. Resected temporal lobe tissue from a human patient with refractory epilepsy but not the temporal lobe tissue from a patient without seizures demonstrated positive MPO immunostaining, suggesting high translational potential for this imaging technology.

CONCLUSION

The findings of this study highlight an important role for MPO in epileptogenesis and show MPO to be a potential therapeutic target and imaging biomarker for epilepsy.

Third International Congress on Epilepsy, Brain, and Mind: Part 2

Epilepsy is both a disease of the brain and the mind. Here, we present the second of two papers with extended summaries of selected presentations of the Third International Congress on Epilepsy, Brain and Mind (April 3-5, 2014; Brno, Czech Republic). Humanistic, biologic, and therapeutic aspects of epilepsy, particularly those related to the mind, were discussed. The extended summaries provide current overviews of epilepsy, cognitive impairment, and treatment, including brain functional connectivity and functional organization; juvenile myoclonic epilepsy; cognitive problems in newly diagnosed epilepsy; SUDEP including studies on prevention and involvement of the serotoninergic system; aggression and antiepileptic drugs; body, mind, and brain, including pain, orientation, the "self-location", Gourmand syndrome, and obesity; euphoria, obsessions, and compulsions; and circumstantiality and psychiatric comorbidities.

Bimodal Imaging of Inflammation with SPECT/CT and MRI Using Iodine-125 Labeled VCAM-1 Targeting Microparticle Conjugates

Upregulation of cell adhesion molecules on endothelial cells is a hallmark of inflammation and an early feature of several neurological conditions. Here, we describe bimodal in vivo imaging of this inflammatory event in the brain using functionalized micron-sized particles of iron oxide. The particles were conjugated to anti-VCAM-1 antibodies and subsequently labeled with iodine-125. Radiolabeling of the antibody-coated particles was straightforward and proceeded in high radiochemical yields using commercially available iodination tubes. The corresponding contrast agent was evaluated in a rat model of cerebral inflammation based on intracerebral injection of tumor necrosis factor alpha and a rat model of status epilepticus. Biodistribution studies and phosphorimaging of cryosections were used to verify in vivo imaging data obtained with single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI). The contrast agent showed rapid and highly localized binding to the vasculature of inflamed brain tissue, and was effectively cleared from the blood pool within 2 min postinjection. Overall, the pattern of hypointensities observed with MRI was in good agreement with the distribution of the contrast agent as determined with SPECT and phosphorimaging; however, conspicuous differences in the signal intensities were observed. The results demonstrate that radiolabeled micron-sized particles of iron oxide enable multimodal in vivo imaging with MRI and nuclear techniques, and highlight the value of validating different imaging methods against one another.

GABAergic inhibition shapes interictal dynamics in awake epileptic mice

Epilepsy is characterized by recurrent seizures and brief, synchronous bursts called interictal spikes that are present in-between seizures and observed as transient events in EEG signals. While GABAergic transmission is known to play an important role in shaping healthy brain activity, the role of inhibition in these pathological epileptic dynamics remains unclear. Examining the microcircuits that participate in interictal spikes is thus an important first step towards addressing this issue, as the function of these transient synchronizations in either promoting or prohibiting seizures is currently under debate. To identify the microcircuits recruited in spontaneous interictal spikes in the absence of any proconvulsive drug or anaesthetic agent, we combine a chronic model of epilepsy with in vivo two-photon calcium imaging and multiunit extracellular recordings to map cellular recruitment within large populations of CA1 neurons in mice free to run on a self-paced treadmill. We show that GABAergic neurons, as opposed to their glutamatergic counterparts, are preferentially recruited during spontaneous interictal activity in the CA1 region of the epileptic mouse hippocampus. Although the specific cellular dynamics of interictal spikes are found to be highly variable, they are consistently associated with the activation of GABAergic neurons, resulting in a perisomatic inhibitory restraint that reduces neuronal spiking in the principal cell layer. Given the role of GABAergic neurons in shaping brain activity during normal cognitive function, their aberrant unbalanced recruitment during these transient events could have important downstream effects with clinical implications.

Hyperthermia aggravates status epilepticus-induced epileptogenesis and neuronal loss in immature rats

This study tightly controlled seizure duration and severity during status epilepticus (SE) in postnatal day 10 (P10) rats, in order to isolate hyperthermia as the main variable and to study its consequences. Body temperature was maintained at 39 ± 1 °C in hyperthermic SE rats (HT+SE) or at 35 ± 1 °C in normothermic SE animals (NT+SE) during 30 min of SE, which was induced by lithium-pilocarpine (3 mEq/kg, 60 mg/kg) and terminated by diazepam and cooling to NT. All video/EEG measures of SE severity were similar between HT+SE and NT+SE pups. At 24h, neuronal injury was present in the amygdala in the HT+SE group only, and was far more severe in the hippocampus in HT+SE than NT+SE pups. Separate groups of animals were monitored four months later for spontaneous recurrent seizures (SRS). Only HT+SE animals developed convulsive SRS. Both HT+SE and NT+SE animals developed electrographic SRS (83% vs. 55%), but SRS frequency and severity were higher in hyperthermic animals (12.5 ± 3.5 vs. 4.2 ± 2.0 SRS/day). The density of hilar neurons was lower, thickness of the amygdala and perirhinal cortex was reduced, and lateral ventricles were enlarged in HT+SE over NT+SE littermates and HT/NT controls. In this model, hyperthermia greatly increased the epileptogenicity of SE and its neuropathological sequelae.

Status epilepticus, blood-brain barrier disruption, inflammation, and epileptogenesis

Over the last 15 years, attention has been focused on dysfunction of the cerebral vasculature and inflammation as important players in epileptogenic processes, with a specific emphasis on failure of the blood-brain barrier (BBB; Fig. 1) (Seiffert et al., 2004; Marchi et al., 2007; Oby and Janigro, 2006; van Vliet et al., 2014; Vezzani et al., 2011) [3-7]. Here, we discuss how the BBB is disrupted as a consequence of SE and how this BBB breakdown may be involved in epileptogenesis. This article is part of a Special Issue entitled "Status Epilepticus".

Ischemic-hypoxic mechanisms leading to hippocampal dysfunction as a consequence of status epilepticus

Status epilepticus (SE) is one of the recognized primary precipitating events that can lead to temporal lobe epilepsy (TLE) associated with hippocampal sclerosis. This type of epilepsy is characterized by poor response to drug treatment, often requiring surgical intervention to remove the mesial temporal regions involved in the seizure onset. However, even neurosurgery may not be completely successful. Thus, the prevention of hippocampal damage and epileptogenesis is currently evaluated as a possible alternative therapeutic approach to prevent the development of pharmacoresistant TLE. Lines of evidence suggest that ischemic-hypoxic lesions might occur in different brain regions, including the hippocampus, during SE. Especially in the hippocampal CA3 region, an ischemic-like lesion develops in the stratum lacunosum-moleculare and is mainly characterized by a loss of astrocytes and neuronal processes and increased immunostaining of pimonidazole which probes areas exposed to hypoxia. Interestingly, these mechanisms can contribute to neuronal cell loss and may be counteracted by drugs that can afford vascular protection, as in the case of ligands of the ghrelin receptor. Notably, some of the ghrelin receptor ligands possess a double edge effect, since they are anticonvulsant and vascular-protective, thus, potentially representing new tools to counteract the consequences of SE. This article is part of a Special Issue entitled "Status Epilepticus".

Blood-brain barrier, bulk flow, and interstitial clearance in epilepsy

Understanding the pathophysiology of epilepsy implies elucidating the neurovascular modifications occurring before or at time of seizures. Cerebrovascular dysfunction provokes or sustains seizures and loss of selective blood-brain barrier (BBB) permeability is a modulator of seizure threshold. However, cerebrovascular pathology in epilepsy extends beyond BBB "leakage" to encompass vascular and parenchymal events. Whenever abnormal accumulation of protein is observed surrounding brain blood vessels, BBB disruption (BBBD) was invoked. Recent clinical and laboratory findings challenged an exclusive role of BBBD in perivascular accumulation of serum-derived products. The circulation of interstitial fluid (ISF) and its bulk flow have emerged as candidate mechanisms which play a role in clearance of CNS waste. Although controversy exists, changes of ISF flow may contribute to CNS disorders through a mechanism encompassing incomplete parenchymal clearance and accompanying accumulation of toxic byproducts. We summarize the evidence in favor and against ISF bulk flow and propose a scenario where abnormal ISF in the epileptic brain allows accumulation of brain protein, sustaining pathophysiology and altering the pharmacology of antiepileptic drugs. We also describe the methods routinely used to dissect out the contribution of BBB-dependent, vascular or paracellular mechanisms to altered neuronal excitability.

Type 1 diabetes exacerbates blood-brain barrier alterations during experimental epileptic seizures in an animal model

The aim of this study was to perform the effects of diabetes on the permeability of the blood-brain barrier (BBB) during pentylenetetrazole (PTZ)-induced epileptic attacks. For this propose, the animals were divided into four groups. These groups contained were intact, PTZ-treated, diabetic and PTZ-treated diabetic individuals, respectively. To evaluate the functioning of the BBB, Evans blue was used as a BBB permeability indicator, and the expressions of zonula occludens-1 and glial fibrillary acidic protein involving the functioning of the BBB were determined immunohistochemically. Also, the changes in the release of serum tumour necrosis factor-alpha and interleukin-10 and interleukin-12 were studied by using enzyme-linked immunosorbent assay method. BBB permeability in the seizures under diabetic conditions showed a considerable increase (p < 0·01) in all of the brain we studied. The immunoreactive staining intensity of zonula occludens-1 and glial fibrillary acidic protein was found reduced in the brain regions of diabetic rats (p < 0·01). However, the serum level of tumour necrosis factor-alpha increased in diabetes and diabetes + PTZ groups, and the serum level of interleukin-12 increased significantly in all experimental groups (p < 0·05). In conclusion, diabetes dramatically increases BBB damage during epileptic seizures, and it may be derived from an elevation of paracellular passage.

Inflammatory mechanisms contribute to the neurological manifestations of tuberous sclerosis complex

Epilepsy and other neurological deficits are common, disabling manifestations of the genetic disorder, tuberous sclerosis complex (TSC). Brain inflammation has been implicated in contributing to epileptogenesis in acquired epilepsy due to brain injury, but the potential role of inflammatory mechanisms in genetic epilepsies is relatively unexplored. In this study, we investigated activation of inflammatory mediators and tested the effects of anti-inflammatory treatment on epilepsy in the Tsc1-GFAP conditional knock-out mouse model of TSC (Tsc1(GFAP)CKO mice). Real-time quantitative RT-PCR, immunohistochemistry, and Western blotting demonstrated increased expression of specific cytokines and chemokines, particularly IL-1β and CXCL10, in the neocortex and hippocampus of Tsc1(GFAP)CKO mice, which was reversed by treatment with a mammalian target of rapamycin complex 1 (mTORC1) inhibitor. Double-labeling immunohistochemical studies indicated that the increased IL-1β was localized primarily to astrocytes. Importantly, the increase in inflammatory markers was also observed in astrocyte culture in vitro and at 2 weeks of age in Tsc1(GFAP)CKO mice before the onset of epilepsy in vivo, indicating that the inflammatory changes were not secondary to seizures. Epicatechin-3-gallate, an inhibitor of IL-1β and CXCL10, at least partially reversed the elevated cytokine and chemokine levels, reduced seizure frequency, and prolonged survival of Tsc1(GFAP)CKO mice. These findings suggest that mTOR-mediated inflammatory mechanisms may be involved in epileptogenesis in the genetic epilepsy, TSC.

Patient-specific detection of cerebral blood flow alterations as assessed by arterial spin labeling in drug-resistant epileptic patients

Electrophysiological and hemodynamic data can be integrated to accurately and precisely identify the generators of abnormal electrical activity in drug-resistant focal epilepsy. Arterial Spin Labeling (ASL), a magnetic resonance imaging (MRI) technique for quantitative noninvasive measurement of cerebral blood flow (CBF), can provide a direct measure of variations in cerebral perfusion associated with the epileptic focus. In this study, we aimed to confirm the ASL diagnostic value in the identification of the epileptogenic zone, as compared to electrical source imaging (ESI) results, and to apply a template-based approach to depict statistically significant CBF alterations. Standard video-electroencephalography (EEG), high-density EEG, and ASL were performed to identify clinical seizure semiology and noninvasively localize the epileptic focus in 12 drug-resistant focal epilepsy patients. The same ASL protocol was applied to a control group of 17 healthy volunteers from which a normal perfusion template was constructed using a mixed-effect approach. CBF maps of each patient were then statistically compared to the reference template to identify perfusion alterations. Significant hypo- and hyperperfused areas were identified in all cases, showing good agreement between ASL and ESI results. Interictal hypoperfusion was observed at the site of the seizure in 10/12 patients and early postictal hyperperfusion in 2/12. The epileptic focus was correctly identified within the surgical resection margins in the 5 patients who underwent lobectomy, all of which had good postsurgical outcomes. The combined use of ESI and ASL can aid in the noninvasive evaluation of drug-resistant epileptic patients.

Wistar Audiogenic Rats (WAR) exhibit altered levels of cytokines and brain-derived neurotrophic factor following audiogenic seizures

Increasing body of evidence suggests that inflammatory and neurotrophic factors might be important for epileptogenesis. Most animal studies demonstrated altered levels of these mediators in drug-induced models of seizures and epilepsy. In the present study, we investigated the production of cytokines and a neurotrophin in the brain of Wistar Audiogenic Rats (WAR), a genetic model of epilepsy, stimulated with high-intensity sound. Four hours after stimulation, animals were decapitated and the hippocampus, inferior colliculus, striatum and cortex were removed for evaluation of the levels of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α and brain derived neurotrophic factor (BDNF). All the cytokines and BDNF levels were increased in the cortex. Increased levels of TNF-α and IL-6 were also observed in the striatum. Finally, TNF-α also increased in the inferior colliculus after the seizures induced by high-intensity sound. Although different studies have demonstrated that the levels of cytokines and BDNF increase in animal models of epilepsy induced by chemical stimuli, we provided here evidence that these mediators are also increased in WAR, a genetic model of epilepsy. Thus, the observed increase in these mediators might be involved in the pathophysiology of epilepsy.

What Elements of the Inflammatory System Are Necessary for Epileptogenesis In Vitro?

The inflammatory and central nervous systems share many signaling molecules, compromising the utility of traditional pharmacological and knockout approaches in defining the role of inflammation in CNS disorders such as epilepsy. In an in vitro model of post-traumatic epileptogenesis, the development of epilepsy proceeded in the absence of the systemic inflammatory system, and was unaffected by removal of cellular mediators of inflammation, including macrophages and T-lymphocytes.

Epileptogenesis in vivo can be altered by manipulation of molecules such as cytokines and complement that subserve intercellular signaling in both the inflammatory and central nervous systems. Because of the dual roles of these signaling molecules, it has been difficult to precisely define the role of systemic inflammation in epileptogenesis. Organotypic hippocampal brain slices can be maintained in culture independently of the systemic inflammatory system, and the rapid course of epileptogenesis in these cultures supports the idea that inflammation is not necessary for epilepsy. However, this preparation still retains key cellular inflammatory mediators. Here, we found that rodent hippocampal organotypic slice cultures depleted of T lymphocytes and microglia developed epileptic activity at essentially the same rate and to similar degrees of severity as matched control slice cultures. These data support the idea that although the inflammatory system, neurons, and glia share key intercellular signaling molecules, neither systemic nor CNS-specific cellular elements of the immune and inflammatory systems are necessary components of epileptogenesis.

A novel anticonvulsant mechanism via inhibition of complement receptor C5ar1 in murine epilepsy models

The role of complement system-mediated inflammation is of key interest in seizure and epilepsy pathophysiology, but its therapeutic potential has not yet been explored. We observed that the pro-inflammatory C5a receptor, C5ar1, is upregulated in two mouse models after status epilepticus; the pilocarpine model and the intrahippocampal kainate model. The C5ar1 antagonist, PMX53, was used to assess potential anticonvulsant actions of blocking this receptor pathway. PMX53 was found to be anticonvulsant in several acute models (6Hz and corneal kindling) and one chronic seizure model (intrahippocampal kainate model). The effects in the 6Hz model were not found in C5ar1-deficient mice, or with an inactive PMX53 analogue suggesting that the anticonvulsant effect of PMX53 is C5ar1-specific. In the pilocarpine model, inhibition or absence of C5ar1 during status epilepticus lessened seizure power and protected hippocampal neurons from degeneration as well as halved SE-associated mortality. C5ar1-deficiency during pilocarpine-induced status epilepticus also was accompanied by attenuation of TNFα upregulation by microglia, suggesting that C5ar1 activation results in TNFα release contributing to disease. Patch clamp studies showed that C5a-induced microglial K(+) outward currents were also inhibited with PMX53 providing a potential mechanism to explain acute anticonvulsant effects. In conclusion, our data indicate that C5ar1 activation plays a role in seizure initiation and severity, as well as neuronal degeneration following status epilepticus. The widespread anticonvulsant activity of PMX53 suggests that C5ar1 represents a novel target for improved anti-epileptic drug development which may be beneficial for pharmaco-resistant patients.

Personalized medicine approaches in epilepsy

Epilepsy affects 50 million persons worldwide, a third of whom continue to experience debilitating seizures despite optimum anti-epileptic drug (AED) treatment. Twelve-month remission from seizures is less likely in female patients, individuals aged 11-36 years and those with neurological insults and shorter time between first seizure and starting treatment. It has been found that the presence of multiple seizures prior to diagnosis is a risk factor for pharmacoresistance and is correlated with epilepsy type as well as intrinsic severity. The key role of neuroinflammation in the pathophysiology of resistant epilepsy is becoming clear. Our work in this area suggests that high-mobility group box 1 isoforms may be candidate biomarkers for treatment stratification and novel drug targets in epilepsy. Furthermore, transporter polymorphisms contributing to the intrinsic severity of epilepsy are providing robust neurobiological evidence on an emerging theory of drug resistance, which may also provide new insights into disease stratification. Some of the rare genetic epilepsies enable treatment stratification through testing for the causal mutation, for example SCN1A mutations in patients with Dravet's syndrome. Up to 50% of patients develop adverse reactions to AEDs which in turn affects tolerability and compliance. Immune-mediated hypersensitivity reactions to AED therapy, such as toxic epidermal necrolysis, are the most serious adverse reactions and have been associated with polymorphisms in the human leucocyte antigen (HLA) complex. Pharmacogenetic screening for HLA-B*15:02 in Asian populations can prevent carbamazepine-induced Stevens-Johnson syndrome. We have identified HLA-A*31:01 as a potential risk marker for all phenotypes of carbamazepine-induced hypersensitivity with applicability in European and other populations. In this review, we explore the currently available key stratification approaches to address the therapeutic challenges in epilepsy.

microRNA and Epilepsy

Epilepsy is a common, serious neurological disease characterized by recurring seizures. Such abnormal, excessive synchronous firing of neurons arises in part because of imbalances in excitation and inhibition in the brain. The process of epileptogenesis, during which the normal brain is transformed after injury to one capable of generating spontaneous seizures, is associated with large-scale changes in gene expression. These contribute to the remodelling of brain networks that permanently alters excitability. Components of the microRNA (miRNA) biogenesis pathway have been found to be altered in brain tissue from epilepsy patients and experimental epileptogenic insults result in select changes to miRNAs regulating neuronal microstructure, cell death, inflammation, and ion channels. Targeting key miRNAs has been shown to alter brain excitability and suppress or exacerbate seizures, indicating potential for miRNA-based therapeutics in epilepsy. Altered miRNA profiles in biofluids may be potentially useful biomarkers of epileptogenesis. In summary, miRNAs represent an important layer of gene expression control in epilepsy with therapeutic and biomarker potential.

Consequences of febrile seizures in childhood

PURPOSE OF REVIEW

There is a long-standing hypothesis that febrile status epilepticus (FSE) can cause brain injury, particularly to the hippocampus. This review will evaluate recent evidence on the relationships between FSE and later epilepsy and cognitive impairments. Potential strategies for minimizing adverse outcomes will be discussed.

RECENT FINDINGS

There are two major longitudinal studies evaluating the outcomes for FSE. These studies provide evidence of acute hippocampal edema that evolves to mesial temporal sclerosis in a small number of children (∼7%). However, none of these children have developed temporal lobe epilepsy. There is also evidence of more global white matter injury. Development is affected, with a loss of about 10 developmental quotient points and there is evidence for accelerated forgetting. These findings do not correlate with MRI parameters. Therefore, FSE can cause a wide spectrum of injury, but the relationship between this and clinically relevant adverse outcomes remains uncertain.

SUMMARY

Although there is accumulating evidence that FSE can cause brain injury, the strategies to minimize the impact remain uncertain. Imaging requires sedation, with inherent risks, and may not be appropriate for all children with FSE, given the small number with significant hippocampal edema that could be a biomarker. The alternative of treating all children requires a very safe drug which currently does not exist.

Epileptic seizures as a manifestation of cow's milk allergy: a studied relationship and description of our pediatric experience

Adverse reactions after ingestion of cow's milk proteins can occur at any age, from birth and even amongst exclusively breast-fed infants, although not all of these are hypersensitivity reactions. The most common presentations related to cow's milk protein allergy are skin reactions, failure to thrive, anaphylaxis as well as gastrointestinal and respiratory disorders. In addition, several cases of cow's milk protein allergy in the literature have documented neurological involvement, manifesting with convulsive seizures in children. This may be due to CNS spread of a peripheral inflammatory response. Furthermore, there is evidence that pro-inflammatory cytokines are responsible for disrupting the blood-brain barrier, causing focal CNS inflammation thereby triggering seizures, although further studies are needed to clarify the pathogenic relationship between atopy and its neurological manifestations. This review aims to analyze current published data on the link between cow's milk protein allergy and epileptic events, highlighting scientific evidence for any potential pathogenic mechanism and describing our clinical experience in pediatrics.