FutureNeuro: translating research into action

One in four people in Ireland will be directly affected by a neurological disorder during their lifetime. An enormous gap remains in translating neuroscience, genetics, and diagnostic discoveries into patient care; the current system for diagnosing, treating, and managing chronic and rare neurological diseases is inadequate and largely fails patients. FutureNeuro is the Science Foundation Ireland (SFI) Research Centre for Chronic and Rare Neurological Diseases, based at the Royal College of Surgeons in Ireland (RCSI), and brings together an internationally recognised multidisciplinary team. FutureNeuro includes neuroscientists, clinical neurologists, geneticists, cell biologists, and analytical and materials chemists from five different third-level institutions’ research teams including RCSI, Trinity College Dublin (TCD), University College Dublin (UCD), Dublin City University (DCU), and National University of Ireland Galway (NUIG). FutureNeuro currently has eight dedicated principal investigators. The vision of FutureNeuro is to provide a uniquely integrated centre that will accelerate translatable discoveries on genetic diagnosis and advanced molecular treatments supported by enabling eHealth technology for chronic and rare neurological diseases. Researchers in FutureNeuro connect to a national clinical network spanning major tertiary referral centres across Ireland, which in turn are linked via national disease-specific electronic health systems. This is globally unique and provides an edge over similar initiatives and a platform to deliver world-leading research. Further, given the size and nature of the healthcare system in Ireland, this is scalable to other neurological disorders. </p

Modulators of neuronal cell death in epilepsy

Experimental and human data have shown that certain seizures cause damage to brain. Such neuronal loss may result in cognitive impairments and perhaps contribute to the development or phenotype of emergent epilepsy. Recent work using genetically modified mice, Tat protein transduction, and viral vectors has shown functional effects of manipulating Bcl-2 and Bcl-w, heat shock proteins, caspases, and their regulators and endonucleases on neuronal death in models of status epilepticus. Ancillary effects on seizure induction and excitability thresholds have emerged for several genes suggesting additional properties of therapeutic potential. Differing hippocampal expression of certain Bcl-2 family genes, elevated endoplasmic reticulum stress chaperones, and death receptor pathway modulation in epilepsy patients support clinical relevance of this focus. These findings may yield potentially valuable adjunctive neuroprotective or anti-epileptogenic strategies

Targeting microRNA-134 for seizure control and disease modification in epilepsy

MicroRNA-134 is a brain-enriched small noncoding RNA that has been implicated in diverse neuronal functions, including regulating network excitability. Increased expression of microRNA-134 has been reported in several experimental epilepsy models and in resected brain tissue from temporal lobe epilepsy patients. Rodent studies have demonstrated that reducing microRNA-134 expression in the brain using antisense oligonucleotides can increase seizure thresholds and attenuate status epilepticus. Critically, inhibition of microRNA-134 after status epilepticus can potently reduce the occurrence of spontaneous recurrent seizures. Altered plasma levels of microRNA-134 have been reported in epilepsy patients, suggesting microRNA-134 may have diagnostic value as a biomarker. This review summarises findings on the cellular functions of microRNA-134, as well as the preclinical evidence supporting anti-seizure and disease-modifying effects of targeting microRNA-134 in epilepsy. Finally, we draw attention to unanswered questions and some of the challenges and opportunities involved in preclinical development of a microRNA-based oligonucleotide treatment for epilepsy

The effects of seizures on the brain: transcriptional profiling using a DNA microarray database

Background: Epilepsy is one of the most common neurological disorders, affecting people of all ages. In recent years, important advances have been made in the study of mechanisms underlying the development of epilepsy using large-scale gene profiling. Changes in the expression of genes involved in neurogenesis, astrogliosis, and axonal and/or dendritic plasticity, and the loss of selective neuronal populations, are some of the significant findings made in previous microarray studies. Aim: To categorise the biological function, cellular compartment localisation and molecular function of genes altered by seizures. Methods: A mouse brain gene expression database containing the results of the effects of seizures on around 35,000 genes was investigated. Results: Genes whose expression was altered at least two-fold as compared to controls, once corrected for multiple comparisons, were included in the analysis (929 genes in total). Gene ontology analysis revealed that cellular activity, immune system, biological adhesion and localisation were the most highly represented processes in the biological function category. Within the cellular component category, genes associated with intracellular organelles and the synapse were most abundant. Finally, within the molecular function category, genes involved in binding and transporter activities (particularly glutamatergic ion channels) were most highly represented. Conclusion: This analysis provides a comprehensive ontology profile of gene expression changes in response to seizure activity in the brain, and may yield new insights into molecular mechanisms underlying the development of epilepsy.</p

Sexual dimorphism in epilepsy and comorbidities in Dravet syndrome mice carrying a targeted deletion of exon 1 of the Scn1a gene

Objective Dravet Syndrome (DS) is a catastrophic form of paediatric epilepsy associated with multiple comorbidities mainly caused by mutations in the SCN1A gene. DS progresses in three different phases termed febrile, worsening and stabilization stage. Mice that are haploinsufficient for Scn1a faithfully model each stage of DS, although various aspects have not been fully described, including the temporal appearance and sex differences of the epilepsy and comorbidities. The aim of the present study was to investigate the epilepsy landscape according to the progression of DS and the long-term co-morbidities in the Scn1a(+/-)tm1Kea DS mouse line that are not fully understood yet. Methods Male and female F1.Scn1a(+/+) and F1.Scn1a(+/-)tm1Kea mice were assessed in the hyperthermia model or monitored by video electroencephalogram (vEEG) and wireless video-EEG according to the respective stage of DS. Long-term comorbidities were investigated through a battery of behaviour assessments in ∼6 month-old mice. Results At P18, F1.Scn1a(+/-)tm1Kea mice showed the expected sensitivity to hyperthermia-induced seizures. Between P21 and P28, EEG recordings in F1.Scn1a(+/-)tm1Kea mice combined with video monitoring revealed a high frequency of SRS and SUDEP. Power spectral analyses of background EEG activity also revealed that low EEG power in multiple frequency bands was associated with SUDEP risk in F1.Scn1a(+/-)tm1Kea mice during the worsening stage of DS. Later, SRS and SUDEP rates stabilized and then declined in F1.Scn1a(+/-)tm1kea mice. SRS and SUDEP in F1.Scn1a(+/-)tm1kea mice displayed variations with the time of day and sex, with female mice displaying higher numbers of seizures and greater SUDEP risk. F1.Scn1a(+/-)tm1kea mice ∼6 month- old displayed fewer behavioural impairments than expected including hyperactivity, impaired exploratory behaviour and poor nest building performance. Significance These results reveal new features of this model that will optimize use and selection of phenotype assays for future studies on the mechanisms, diagnosis, and treatment of DS.Key point boxScn1a(+/-)tm1kea DS mouse model faithfully reproduces the three stages of DSSex of F1.Scn1a(+/-)tm1kea mice influences the epilepsy phenotypeF1.Scn1a(+/-)tm1kea develop some of the long-term comorbidities of DS</p

Electrochemiluminescent detection of epilepsy biomarker miR-134 using a metal complex light switch

The detection of a key biomarker in epilepsy, miR-134, using an environmentally sensitive electrochemiluminescent luminophore, [Ru(DPPZ)2 PIC]2+, is reported, DPPZ is dipyrido[3,2-a:2′,3′-c]phenazine) and PIC is (2,2′-bipyridyl)-2(4-carboxy phenyl) imidazo [4,5][1,10] phenanthroline. A thiolated capture strand is first labelled with [Ru(DPPZ)2 PIC]2+ and then adsorbed onto a gold electrode. No significant electrochemiluminescence, ECL, is observed for immobilised Ru-labelled capture strands which is consistent with the light-switch dye being exposed to the aqueous solution. In sharp contrast, binding of the target turns on ECL. The ECL intensity, IECL, depends on the number of adenine “spacer” bases between the end of the capture sequence and the dye. The ECL intensity for the optimised system increases linearly with increasing miR-134 concentration from 100 nM to approximately 20 μM. Single and double base mismatches produce IECL that are only approximately 30% and 8% respectively of that observed for the fully complementary target reflecting differences in their association constants. Significantly, the presence of BSA protein causes IECL to increase by less 5% in either the single or duplex circumstances. Finally, the ability of the sensor to quantify miR-134 in unprocessed plasma samples from healthy volunteers and people with epilepsy is reported

Life-span characterization of epilepsy and comorbidities in Dravet syndrome mice carrying a targeted deletion of exon 1 of the Scn1a gene

Objective: Dravet Syndrome (DS) is a catastrophic form of paediatric epilepsy associated with multiple comorbidities mainly caused by mutations in the SCN1A gene. DS progresses in three different phases termed febrile, worsening and stabilization stage. Mice that are haploinsufficient for Scn1a faithfully model each stage of DS, although various aspects have not been fully described, including the temporal appearance and sex differences of the epilepsy and comorbidities. The aim of the present study was to investigate the epilepsy landscape according to the progression of DS and the long-term co-morbidities in the Scn1a(+/-)tm1Kea DS mouse line that are not fully understood yet. Methods: Male and female F1.Scn1a(+/+) and F1.Scn1a(+/-)tm1Kea mice were assessed in the hyperthermia model or monitored by video electroencephalogram (vEEG) and wireless video-EEG according to the respective stage of DS. Long-term comorbidities were investigated through a battery of behaviour assessments in ~6 month-old mice. Results: At P18, F1.Scn1a(+/-)tm1Kea mice showed the expected sensitivity to hyperthermia-induced seizures. Between P21 and P28, EEG recordings in F1.Scn1a(+/-)tm1Kea mice combined with video monitoring revealed a high frequency of SRS and SUDEP (sudden unexpected death in epilepsy). Power spectral analyses of background EEG activity also revealed that low EEG power in multiple frequency bands was associated with SUDEP risk in F1.Scn1a(+/-)tm1Kea mice during the worsening stage of DS. Later, SRS and SUDEP rates stabilized and then declined in F1.Scn1a(+/-)tm1kea mice. Incidence of SRS ending with death in F1.Scn1a(+/-)tm1kea mice displayed variations with the time of day and sex, with female mice displaying higher numbers of severe seizures resulting in greater SUDEP risk. F1.Scn1a(+/-)tm1kea mice ~6 month-old displayed fewer behavioural impairments than expected including hyperactivity, impaired exploratory behaviour and poor nest building performance. Significance: These results reveal new features of this model that will optimize use and selection of phenotype assays for future studies on the mechanisms, diagnosis, and treatment of DS.</p

Life-span characterization of epilepsy and comorbidities in Dravet syndrome mice carrying a targeted deletion of exon 1 of the Scn1a gene

Objective: Dravet Syndrome (DS) is a catastrophic form of paediatric epilepsy associated with multiple comorbidities mainly caused by mutations in the SCN1A gene. DS progresses in three different phases termed febrile, worsening and stabilization stage. Mice that are haploinsufficient for Scn1a faithfully model each stage of DS, although various aspects have not been fully described, including the temporal appearance and sex differences of the epilepsy and comorbidities. The aim of the present study was to investigate the epilepsy landscape according to the progression of DS and the long-term co-morbidities in the Scn1a(+/-)tm1Kea DS mouse line that are not fully understood yet. Methods: Male and female F1.Scn1a(+/+) and F1.Scn1a(+/-)tm1Kea mice were assessed in the hyperthermia model or monitored by video electroencephalogram (vEEG) and wireless video-EEG according to the respective stage of DS. Long-term comorbidities were investigated through a battery of behaviour assessments in ~6 month-old mice. Results: At P18, F1.Scn1a(+/-)tm1Kea mice showed the expected sensitivity to hyperthermia-induced seizures. Between P21 and P28, EEG recordings in F1.Scn1a(+/-)tm1Kea mice combined with video monitoring revealed a high frequency of SRS and SUDEP (sudden unexpected death in epilepsy). Power spectral analyses of background EEG activity also revealed that low EEG power in multiple frequency bands was associated with SUDEP risk in F1.Scn1a(+/-)tm1Kea mice during the worsening stage of DS. Later, SRS and SUDEP rates stabilized and then declined in F1.Scn1a(+/-)tm1kea mice. Incidence of SRS ending with death in F1.Scn1a(+/-)tm1kea mice displayed variations with the time of day and sex, with female mice displaying higher numbers of severe seizures resulting in greater SUDEP risk. F1.Scn1a(+/-)tm1kea mice ~6 month-old displayed fewer behavioural impairments than expected including hyperactivity, impaired exploratory behaviour and poor nest building performance. Significance: These results reveal new features of this model that will optimize use and selection of phenotype assays for future studies on the mechanisms, diagnosis, and treatment of DS.</p

The anti-inflammatory compound candesartan cilexetil improves neurological outcomes in a mouse model of neonatal hypoxia

Recent studies suggest that mild hypoxia-induced neonatal seizures can trigger an acute neuroinflammatory response leading to long-lasting changes in brain excitability along with associated cognitive and behavioral deficits. The cellular elements and signaling pathways underlying neuroinflammation in this setting remain incompletely understood but could yield novel therapeutic targets. Here we show that brief global hypoxia-induced neonatal seizures in mice result in transient cytokine production, a selective expansion of microglia and long-lasting changes to the neuronal structure of pyramidal neurons in the hippocampus. Treatment of neonatal mice after hypoxia-seizures with the novel anti-inflammatory compound candesartan cilexetil suppressed acute seizure-damage and mitigated later-life aggravated seizure responses and hippocampus-dependent learning deficits. Together, these findings improve our understanding of the effects of neonatal seizures and identify potentially novel treatments to protect against short and long-lasting harmful effects. </p

Context-Specific Switch from Anti- to Pro-epileptogenic Function of the P2Y1 Receptor in Experimental Epilepsy

This is the first study to fully characterize the contribution of a metabotropic purinergic P2Y receptor during acute seizures and epilepsy. The findings suggest that targeting P2Y1 may offer a potential novel treatment strategy for drug-refractory status epilepticus and epilepsy. Our data demonstrate a context-specific role of P2Y1 activation during seizures, switching from a proconvulsiveto an anticonvulsive role depending on physiopathological context. Thus, our study provides a possible explanation for seemingly conflicting results obtained between studies of different brain diseases where P2Y1 targeting has been proposed as a potential treatment strategy and highlights that the timing of pharmacological interventions is of critical importance to the understanding of how receptors contribute to the generation of seizures and the development of epilepsy