EPITARGET NEWS | Issue 4 | 08/2016
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EPITARGET NEWS | Issue 4 | 08/2016

Welcome to the fourth EPITARGET newsletter!

In the 4th issue of the EPITARGET newsletter, we would like to update you on the latest EPITARGET publications, recent presentations and posters as well as upcoming EPITARGET events.


Upcoming EPITARGET events

4th General Assembly Meeting in Marseille 26-28 October 2016

The EPITARGET Consortium will meet again in October 2016 in Marseille. The meeting is hosted by EPITARGET partner Aix Marseille Université. At the meeting all partners get the chance to update each other on the work done since the last meeting and to discuss the next steps and potential challenges.

The meeting will be preceded by the 2nd EPITARGET Young Researchers’ Symposium during which the young investigators of EPITARGET will get the chance to present their work in presentations as well as posters.

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EPITARGET publications - Short summaries

Recent EPITARGET Publications sorted by PubMed ID

Gast H, Niediek J, Schindler K, Boström J, Coenen VA, Beck H, Elger CE, Mormann F. Burst firing of single neurons in the human medial temporal lobe changes before epileptic seizures. Clin Neurophysiol 2016, epub ahead of print

Recording from single neurons in the brains of epilepsy patients, we observe excessive burst firing in regions close to the seizure onset zone during seizure-free periods.  This excess burstiness is found only for putative principal cells, not for interneurons, cannot be explained by different average firing rates or ratios of these two cell types, and vanishes in the minutes before seizure occurrence.  Deviating from traditional theories on seizure initiation, burst firing could represent a protective phenomenon preventing seizure occurrence.

Avaliani N, Andersson M, Runegaard AH, Woldbye D, Kokaia M. DREADDs suppress seizure-like activity in a mouse model of pharmacoresistant epileptic brain tissue. Gene Ther. 2016 Aug 4

The hM4Di is a mutated muscarinic receptor, a DREADD (designer receptor activated by designer drug), selectively activated by otherwise inert clozapine-N-oxide (CNO), which leads to hyperpolarization in neurons. Using viral vector-based gene transfection, we demonstrated that hM4Di-induced hyperpolarization of neurons by CNO effectively suppresses so-called stimulation induced bursting (STIB), an epileptiform activity, in mouse organotypic hippocampal slice cultures (OHSCs). As we also found that STIB in mouse OHSCs is resistant to common anti-epilepsy drug, valproic acid, collectively our findings suggest that DREADD-based gene therapy strategy may be effective in suppressing seizure activity in pharmacoresistant epileptic brain tissue.

Terrone G, Pauletti A, Pascente R, Vezzani A. Preventing epileptogenesis: A realistic goal? Pharmacol Res. 2016;110:96-100

The definition of the pathologic process of epileptogenesis has considerably changed over the past few years due to a better knowledge of the dynamics of the associated molecular modifications and to clinical and experimental evidence of progression of the epileptic condition beyond the occurrence of the first seizures. Interference with this chronic process may lead to the development of novel preventive therapies which are still lacking. Notably, epileptogenesis is often associated with comorbid behaviors which are now considered primary outcome measures for novel therapeutics. Anti-epileptogenic interventions may improve not only seizure onset and their frequency and severity but also comorbidities and cell loss, and when applied after the onset of the disease may provide disease-modifying effects by favorably modifying the disease course. In the preclinical arena, several novel targets for anti-epileptogenic and disease-modifying interventions are being characterized and validated in rodent models of epileptogenesis. To move proof-of-concept anti-epileptogenesis studies to validation in preclinical trials and eventually to clinical translation is a challenging task which would be greatly facilitated by the development of non-invasive biomarkers of epileptogenesis. Biomarker discovery together with testing potential novel drugs would provide a major advance in the treatment of human epilepsy beyond the pure symptomatic control of seizures.

Pascente R, Frigerio F, Rizzi M, Porcu L, Boido M, Davids J, Zaben M, Tolomeo D, Filibian M, Gray WP, Vezzani A, Ravizza T. Cognitive deficits and brain myo-Inositol are early biomarkers of epileptogenesis in a rat model of epilepsy. Neurobiol Dis. 2016 93:146-155

One major unmet clinical need in epilepsy is the identification of therapies to prevent or arrest epilepsy development in patients exposed to a potential epileptogenic insult. The development of such treatments has been hampered by the lack of non-invasive biomarkers that could be used to identify the patients at-risk, thereby allowing to design affordable clinical studies. Our goal was to test the predictive value of cognitive deficits and brain astrocyte activation for the development of epilepsy following a potential epileptogenic injury. We used a model of epilepsy induced by pilocarpine-evoked status epilepticus (SE) in 21-day old rats where 60-70% of animals develop spontaneous seizures after around 70 days, although SE is similar in all rats. Learning was evaluated in the Morris water-maze at days 15 and 65 post-SE, each time followed by proton magnetic resonance spectroscopy for measuring hippocampal myo-Inositol levels, a marker of astrocyte activation. Rats were video-EEG monitored for two weeks at seven months post-SE to detect spontaneous seizures, then brain histology was done. Behavioral and imaging data were retrospectively analysed in epileptic rats and compared with non-epileptic and control animals. Rats displayed spatial learning deficits within three weeks from SE. However, only epilepsy-prone rats showed accelerated forgetting and reduced learning rate compared to both rats not developing epilepsy and controls. These deficits were associated with reduced hippocampal neurogenesis. myo-Inositol levels increased transiently in the hippocampus of SE-rats not developing epilepsy while this increase persisted until spontaneous seizures onset in epilepsy-prone rats, being associated with a local increase in S100β-positive astrocytes. Neuronal cell loss was similar in all SE-rats. Our data show that behavioral deficits, together with a non-invasive marker of astrocyte activation, predict which rats develop epilepsy after an acute injury.

van Scheppingen J, Iyer AM, Prabowo AS, Mühlebner A, Anink JJ, Scholl T, Feucht M, Jansen FE, Spliet WG, Krsek P, Zamecnik J, Buccoliero AM, Giordano F, Genitori L, Kotulska K, Jozwiak S, Jaworski J, Liszewska E, van Vliet EA, Aronica E. Expression of microRNAs miR21, miR146a, and miR155 in tuberous sclerosis complex cortical tubers and their regulation in human astrocytes and SEGA-derived cell cultures. Glia. 2016 Jun;64(6):1066-82

Tuberous sclerosis complex (TSC) is a genetic disease presenting with multiple neurological symptoms including epilepsy, mental retardation, and autism. Abnormal activation of various inflammatory pathways has been observed in astrocytes in brain lesions associated with TSC. Increasing evidence supports the involvement of microRNAs in the regulation of astrocyte-mediated inflammatory response. This study provides supportive evidence that inflammation-related microRNAs play a role in TSC. In particular, miR146a and miR155 appear to be key players in the regulation of astrocyte-mediated inflammatory response, with miR146a as most interesting anti-inflammatory therapeutic candidate.

Andrzejak RG, Rummel C, Mormann F, Schindler K. All together now: Analogies between chimera state collapses and epileptic seizures. Sci Rep 2016;9:23000

Conceptually and structurally simple mathematical models of coupled oscillator networks can show a rich variety of complex dynamics, providing fundamental insights into many real-world phenomena. A recent and not yet fully understood example is the collapse of coexisting synchronous and asynchronous oscillations into a globally synchronous motion found in networks of identical oscillators. Here we show that this sudden collapse is promoted by a further decrease of synchronization, rather than by critically high synchronization. This strikingly counterintuitive mechanism can be found also in nature, as we demonstrate on epileptic seizures in humans. Analyzing spatiotemporal correlation profiles derived from intracranial electroencephalographic recordings (EEG) of seizures in epilepsy patients, we found a pronounced decrease of correlation at the seizure onsets. Applying our findings in a closed-loop control scheme to models of coupled oscillators in chimera states, we succeed in both provoking and preventing outbreaks of global synchronization. Our findings not only advance the understanding of networks of coupled dynamics but can open new ways to control them, thus offering a vast range of potential new applications.

Woitecki AM, Müller JA, van Loo KM, Sowade RF, Becker AJ, Schoch S. Identification of Synaptotagmin 10 as Effector of NPAS4-Mediated Protection from Excitotoxic Neurodegeneration. J Neurosci. 2016 Mar 2;36(9):2561-70

Aberrant synaptic activity is observed in many neurological disorders and has been suggested as an important factor contributing to the pathophysiology. Intriguingly, pathophysiological activity can also trigger signaling cascades mediating potentially compensatory neuroprotection against excitotoxic insult. The paper by Woitecki et al. identifies a new neuroprotective signaling cascade involving the activity-induced transcriptional regulator NPAS4 and the vesicular Ca2+-sensor protein Synaptotagmin 10 (Syt10). Syt10 is required for NPAS4 to protect hippocampal neurons against excitotoxic cell death. NPAS4 in turn controls the activity of the Syt10 gene, which is strongly induced by pathophysiological activity. These results uncover an entirely unexpected, novel function of Syt10 underlying the response of neurons to pathophysiological activity and provide new therapeutic perspectives for neurological disorders.

Drion CM, Borm LE, Kooijman L, Aronica E, Wadman WJ, Hartog AF, van Vliet EA, Gorter JA. Effects of rapamycin and curcumin treatment on the development of epilepsy after electrically-induced status epilepticus in rats. Epilepsia. 2016 May;57(5):688-97

Inhibition of the mammalian target of rapamycin (mTOR) pathway has been suggested as a possible antiepileptogenic strategy in temporal lobe epilepsy (TLE). Here we aim to elucidate whether mTOR inhibition has antiepileptogenic and/or antiseizure effects using different treatment strategies in the electrogenic post-status epilepticus (SE) rat model. This study indicates that rapamycin cannot prevent epilepsy in the electrical stimulation post-SE rat model but has seizure-suppressing properties as long as rapamycin blood levels are sufficiently high. Oral curcumin treatment had no effect on chronic seizures, possibly because it did not reach the brain at adequate levels.

Twele F, Töllner K, Brandt C, Löscher W. Significant effects of sex, strain, and anesthesia in the intrahippocampal kainate mouse model of mesial temporal lobe epilepsy. Epilepsy Behav. 2016 Feb;55:47-56

The intrahippocampal kainate mouse model of mesial temporal lobe epilepsy is increasingly being used for studies on epileptogenesis and antiepileptogenesis. One goal of this study was to investigate whether sex has an influence on latent period and epileptogenesis in this model. Another aspect that was examined was whether mouse strain differences in epileptogenesis exist. Finally, we examined the effects of different types of anesthesia (chloral hydrate, isoflurane) on kainate-induced status epilepticus (SE) and epileptogenesis. In male NMRI mice with chloral hydrate anesthesia during kainate injection, SE was followed by a seizure-free latent period of 10-14 days if hippocampal paroxysmal discharges (HPDs) recorded from the kainate focus were considered the onset of epilepsy. Anesthesia with isoflurane led to a more rapid onset and higher severity of SE, and not all male NMRI mice exhibited a seizure-free latent period. Female NMRI mice differed from male animals in the lack of any clear latent period, independently of anesthesia type. Furthermore, HPDs were only rarely observed. These problems were not resolved by decreasing the dose of kainate or using other strains (C57BL/6, FVB/N) of female mice. The present data are the first to demonstrate marked sex-related differences in the latent period following brain injury in a rodent model of acquired epilepsy. Furthermore, our data demonstrate that the choice of anesthetic agent during kainate administration affects SE severity and as a consequence, the latent period, which may explain some of the differences reported for this model in the literature.

Iori V, Frigerio F, Vezzani A. Modulation of neuronal excitability by immune mediators in epilepsy. Curr Opin Pharmacol. 2016 Feb;26:118-23

A complex set of inflammatory molecules and their receptors has been described in epileptogenic foci in different forms of pharmacoresistant epilepsies. By activating receptor-mediated pathways in neurons, these molecules have profound neuromodulatory effects that are distinct from their canonical activation of immune functions. Importantly, the neuromodulatory actions of some inflammatory molecules contribute to hyperexcitability in neural networks that underlie seizures. This review summarizes recent findings related to the role of cytokines (IL-1beta and TNF-alpha) and danger signals (HMGB1) in decreasing seizure threshold, thereby contributing to seizure generation and the associated neuropathology. We will discuss preclinical studies suggesting that pharmacological inhibition of specific inflammatory signals may be useful to treat drug-resistant seizures in human epilepsy, and possibly arrest epileptogenesis in individuals at risk of developing the disease.

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EPITARGET - Presentations

Selection of recent presentations

Aronica E. microRNAs as a therapeutic target: how far are we from the patient’s bed? Dutch Neuroscience Meeting. 8 June 2016: Symposium.

Aronica E. Inflammation and microRNA based regulation of inflammatory responses in epilepsy-associated pathologies. Seminar at Gladstone Institute of Neurological Disease. San Francisco 23 June 2016 and CURE Seminar at Stanford University School of Medicine, 24 June 2016. 

Szydłowska K. Regulatory small and long ncRNAs: Durat et lucet. EMBO Practical Course. 11 June 2016 in Trento, Italy.

van Vliet EA. Targets and biomarkers for antiepileptogenesis. 18th international clinical symposium Kempenhaeghe, 3 March 2016 in Heeze, The Netherlands.

van Vliet EA. Extracellular matrix molecules and modulation by miRNAs in epilepsy. BBB Nedwork meeting, 18 March 2016 in Leiden, The Netherlands.

van Vliet EA. Epilepsy and blood-brain barrier dysfunction. AMC/VUmc Neuropathology Research meeting, 2 June 2016 in Amsterdam, The Netherlands.

Vezzani A. Neuro-inflammation and epileptogenic process. Neurosciences in Intensive Care International Symposium (NICIS), 16-17 June 2016, Institut Pasteur, Paris.

Vezzani A. Preclinical data on the role of inflammation in epileptogenesis. 9th International Epilepsy Colloqium - Surgical and targeted treatments for acquired lesions, 22-24 June 2016, Westminster, London.

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EPITARGET - Poster presentations

Selection of recent poster presentations

Broekaart DWM, van Scheppingen J, Zuidberg MRJ, Anink JJ, Baayen JC, Gorter JA, Aronica E, van Vliet EA. Increased expression of (immuno)proteasome subunits in experimental and human temporal lobe epilepsy. Dutch Neuroscience Meeting 9-10 June 2016 in Lunteren, The Netherlands.

Drion CM, Kooijman L, Aronica E, van Vliet EA, Chameau PJP, Gorter JA. Effects of inhibition of the mammalian target of rapamycin (mTOR) pathway in the hippocampal slice culture model for temporal lobe epilepsy. Dutch Neuroscience Meeting 9-10 June 2016 in Lunteren, The Netherlands.

Geijtenbeek KW, van Scheppingen J, van Vliet EA, Aronica E. Modulation of proteasome subunits by rapamycin and curcumin in cultured human astrocytes. Dutch Neuroscience Meeting 9-10 June 2016 in Lunteren, The Netherlands.

Pustjens B, Korotkov A, van Scheppingen J, Broekaart DWM, van Vliet EA, Aronica E. Extracellular matrix molecules in mesial temporal lobe epilepsy and their modulation by miRNAs in cultured human astrocytes. Dutch Neuroscience Meeting 9-10 June 2016 in Lunteren, The Netherlands.

van Scheppingen J, Iyer AM, Anink JJ, Mühlebner A, Scholl T, Jansen FE, Spliet WG, Buccoliero AM, Giordano F, Genitori L, Kotulska K, Jozwiak S, Jaworski J, Liszewska E, van Vliet EA, Aronica E. Expression of inflammation related microRNAs miR21, miR146a and miR155 in tuberous sclerosis complex cortical tubers and their modulation in SEGA cell cultures. Dutch Neuroscience Meeting 9-10 June 2016 in Lunteren, The Netherlands.

Roncon P, Srivastava P, Lukasiuk K, Gorter JA, Aronica E, Petretto E, Pitkänen A, Johnson MR, Simonato M. Meta-analysis of microRNAs dysregulated in different models of epilepsy. FENS Forum for Neuroscience 2-6 July 2016 in Copenhagen, Denmark.
Temporal lobe epilepsy (TLE) often develops secondary to an initial brain insult after a latency period in which patients are apparently well. Patients at-risk of developing epilepsy following brain injury cannot be identified, and the available anti-epileptic drugs are ineffective in preventing the development of epilepsy. MicroRNAs (miRNAs) are promising candidates to become therapeutic targets for both prevention and treatment. Since it is impossible to study miRNA changes in the human brain during the latency phase, animal models have been used. However, individual studies have been relatively underpowered to detect the spectrum of miRNA changes associated with epileptogenesis and epilepsy. We performed a meta-analysis of miRNA microarray studies in the latency and in the chronic phases of experimental animal models of TLE, in order to (a) provide increased power to identify miRNAs associated with epileptogenesis and epilepsy and (b) detect miRNA changes across heterogeneous models of epilepsy. Following Z-score transformation of miRNA expression in each dataset, we performed the meta-analysis using a random effects model with the DerSimonian and Laird method. The analysis identified 44 miRNAs that are significantly dysregulated during latency and 8 miRNAs dysregulated in the chronic epileptic phase, as compared to the control group. The dysregulation of these miRNAs may be disease-mediated rather than model-dependent. Gene Ontology enrichment analysis on the validated targets of those miRNAs that are differentially expressed in latency revealed terms connected to specific neuronal fields. However, further analyses are required to establish which miRNAs regulate epileptogenic pathways.

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EPITARGET is a Collaboration Project funded by the European Union under the 7th Framework Programme under grant agreement n° 602102. Copyright | Imprint

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