Advancing research toward faster diagnosis, better treatment, and end of stigma in epilepsy

Plasma neurofilament heavy chain is a prognostic biomarker for the development of severe epilepsy after experimental traumatic brain injury

OBJECTIVE

This study was undertaken to test whether the postinjury plasma concentration of phosphorylated neurofilament heavy chain (pNF-H), a marker of axonal injury, is a prognostic biomarker for the development of posttraumatic epilepsy.

METHODS

Tail vein plasma was sampled 48 h after traumatic brain injury (TBI) from 143 rats (10 naïve, 21 controls, 112 with lateral fluid percussion injury) to quantify pNF-H by enzyme-linked immunosorbent assay. During the 6th postinjury month, rats underwent 30 days of continuous video-electroencephalographic monitoring to detect unprovoked seizures and evaluate epilepsy severity. Somatomotor (composite neuroscore) and spatial memory (Morris water maze) testing and quantitative T2 magnetic resonance imaging were performed to assess comorbidities and lesion severity.

RESULTS

Of the 112 TBI rats, 25% (28/112) developed epilepsy (TBI+) and 75% (84/112) did not (TBI-). Plasma pNF-H concentrations were higher in TBI+ rats than in TBI- rats (p < .05). Receiver operating characteristic curve analysis indicated that plasma pNF-H concentration distinguished TBI+ rats from TBI- rats (area under the curve [AUC] = .647, p < .05). Differentiation was stronger when comparing TBI+ rats exhibiting severe epilepsy (≥3 seizures/month) with all other TBI rats (AUC = .732, p < .01). Plasma pNF-H concentration on day 2 (D2) distinguished TBI+ rats with seizure clusters from other TBI rats (AUC = .732, p < .05). Higher plasma pNF-H concentration on D2 after TBI correlated with lower neuroscores on D2 (p < .001), D6 (p < .001), and D14 (p < .01). Higher pNF-H concentration on D2 correlated with greater T2 signal abnormality volume on D2 (p < .001) and D7 (p < .01) and larger cortical lesion area on D182 (p < .01). Plasma pNF-H concentration on D2 did not correlate with Morris water maze performance on D37-D39.

SIGNIFICANCE

Plasma pNF-H is a promising clinically translatable prognostic biomarker for the development of posttraumatic epilepsy with frequent seizures or seizure clusters.

Action of Botulinum Neurotoxin E Type in Experimental Epilepsies

Botulinum neurotoxins (BoNTs) are zinc endopeptidases produced by the Clostridium genus of anerobic bacteria, largely known for their ability to cleave synaptic proteins, leading to neuromuscular paralysis. In the central nervous system, BoNTs are known to block the release of glutamate neurotransmitter, and for this reason, researchers explored the possible therapeutic action in disorders characterized by neuronal hyperactivity, such as epilepsy. Thus, using multidisciplinary approaches and models of experimental epilepsy, we investigated the pharmacological potential of BoNT/E serotype. In this review, written in memory of Prof. Matteo Caleo, a pioneer in these studies, we go back over the hypotheses and experimental approaches that led us to the conclusion that intrahippocampal administration of BoNT/E (i) displays anticonvulsant effects if prophylactically delivered in a model of acute generalized seizures; (ii) does not have any antiepileptogenic action after the induction of status epilepticus; (iii) reduces frequency of spontaneous seizures in a model of recurrent seizures if delivered during the chronic phase but in a transient manner. Indeed, the control on spontaneous seizures stops when BoNT/E effects are off (few days), thus limiting its pharmacological potential in humans.

Shaping the future of European epilepsy research: Final meeting report from EPICLUSTER

Collaboration is essential to the conduct of basic, applied and clinical research and its translation into the technologies and treatments urgently needed to improve the lives of people living with brain diseases and the health professionals who care for them. EPICLUSTER was formed in 2019 by the European Brain Research Area (EBRA) to support the coordination of epilepsy research in Europe. A key objective was to provide a platform to discuss shared research priorities by bringing together scientists and clinicians with multiple stakeholders including patient organisations and industry and the networks and infrastructures that provide healthcare and support research. Additional objectives were to facilitate access and sharing of data and biosamples, working together to ensure epilepsy is a priority for research funding, and embedding a culture of public and patient involvement (PPI) among epilepsy researchers. In this meeting report, we summarise the shared research priorities discussed by the leadership of EPICLUSTER at the recent final meeting. We also briefly review the discussion on patient and industry priorities, guidance on starting PPI for epilepsy researchers, and the sustainability of funding and infrastructures needed to ensure a comprehensive stakeholder-embedded community for epilepsy research.

miRNAs and isomiRs: Serum-Based Biomarkers for the Development of Intellectual Disability and Autism Spectrum Disorder in Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is a rare multi-system genetic disorder characterized by a high incidence of epilepsy and neuropsychiatric manifestations known as tuberous-sclerosis-associated neuropsychiatric disorders (TANDs), including autism spectrum disorder (ASD) and intellectual disability (ID). MicroRNAs (miRNAs) are small regulatory non-coding RNAs that regulate the expression of more than 60% of all protein-coding genes in humans and have been reported to be dysregulated in several diseases, including TSC. In the current study, RNA sequencing analysis was performed to define the miRNA and isoform (isomiR) expression patterns in serum. A Receiver Operating Characteristic (ROC) curve analysis was used to identify circulating molecular biomarkers, miRNAs, and isomiRs, able to discriminate the development of neuropsychiatric comorbidity, either ASD, ID, or ASD + ID, in patients with TSC. Part of our bioinformatics predictions was verified with RT-qPCR performed on RNA isolated from patients’ serum. Our results support the notion that circulating miRNAs and isomiRs have the potential to aid standard clinical testing in the early risk assessment of ASD and ID development in TSC patients.

Seizure Susceptibility and Sleep Disturbance as Biomarkers of Epileptogenesis after Experimental TBI

Objectives: We investigated whether seizure susceptibility increases over weeks−months after experimental traumatic brain injury (TBI), and whether seizure susceptibility in rats predicts the development of post-traumatic epilepsy (PTE) or epileptiform activity. We further investigated whether rats develop chronic sleep disturbance after TBI, and whether sleep disturbance parameters—alone or in combination with pentylenetetrazol (PTZ) test parameters—could serve as novel biomarkers for the development of post-traumatic epileptogenesis. Methods: TBI was induced in adult male Sprague-Dawley rats with lateral fluid-percussion injury. Sham-operated experimental controls underwent craniectomy without exposure to an impact force. Seizure susceptibility was tested with a PTZ test (30 mg/kg, intraperitoneally) on day (D) 30, D60, D90, and D180 after TBI (n = 28) or sham operation (n = 16) under video electroencephalogram (vEEG). In the 7th post-injury month, rats underwent continuous vEEG monitoring to detect spontaneous seizures and assess sleep disturbances. At the end of the experiments, rats were perfused for brain histology. Results: In the TBI group, the percentage of rats with PTZ-induced seizures increased over time (adjusted p < 0.05 compared with D30). Combinations of three PTZ test parameters (latency to the first epileptiform discharge (ED), number of EDs, and number of PTZ-induced seizures) survived the leave-one-out validation for differentiating rats with or without epileptiform activity, indicating an area under the receiver operating curve (AUC) of 0.743 (95% CI 0.472−0.992, p = 0.05) with a misclassification rate of 36% on D90, and an AUC of 0.752 (95% CI 0.483−0.929, p < 0.05) with a misclassification rate of 32% on D180. Sleep analysis revealed that the number of transitions to N3 or rapid eye movement (REM) sleep, along with the total number of transitions, was increased in the TBI group during the lights-on period (all p < 0.05). The sleep fragmentation index during the lights-on period was greater in the TBI rats than in sham-operated rats (p < 0.05). A combination of sleep parameters showed promise as diagnostic biomarkers of prior TBI, with an AUC of 0.792 (95% CI 0.549−0.934, p < 0.01) and a misclassification rate of 28%. Rats with epilepsy or any epileptiform activity had more transitions from N3 to the awake stage (p < 0.05), and the number of N3−awake transitions differentiated rats with or without epileptiform activity, with an AUC of 0.857 (95% CI 0.651−1.063, p < 0.01). Combining sleep parameters with PTZ parameters did not improve the biomarker performance. Significance: This is the first attempt to monitor the evolution of seizure susceptibility over months in a well-described rat model of PTE. Our data suggest that assessment of seizure susceptibility and sleep disturbance can provide diagnostic biomarkers of prior TBI and prognostic biomarkers of post-traumatic epileptogenesis.

Novel and emerging therapeutics for genetic epilepsies

INTRODUCTION

Disease-specific treatments are available only for a minority of patients with genetic epilepsies, while the rest are treated with anticonvulsants, which are ineffective in almost one-third of patients.

AREAS COVERED

Recently approved and the most effective emerging therapeutics under development for the treatment of genetic epilepsies are overviewed after systematic search and analysis of relevant literature.

EXPERT OPINION

New and emerging drugs for genetic epilepsies exploit one of the two approaches: inhibiting hyperactive brain foci through blocking excitatory or augmenting inhibitory neurotransmission, or correcting the underlying genetic defect. The first is limited by insufficient selectivity of available compounds, and the second by imperfection of currently used vectors of genetic material, unselective and transient transgene expression. Besides, the treatment may come too late, after structural abnormalities and epilepsy deterioration takes place. However, with recent improvements, we can expect to see soon gradual decline in the number of patients with therapy-resistant genetic epilepsies.

Response to Sodium Channel blocking Antiseizure medications and coding polymorphisms of Sodium Channel genes in Taiwanese epilepsy patients

Background

Many antiseizure medications (ASMs) control seizures by blocking voltage-dependent sodium channels. Polymorphisms of sodium channel genes may affect the response to ASMs due to altering the effect of ASMs on blocking sodium channels.

Methods

We conducted a retrospective study of epilepsy patients followed up at the Neurological Department of Kaohsiung Chang Gung Memorial Hospital, Taiwan between January 2010 and December 2018. We categorized the patients into response, partial response, and failure to sodium channel blocking ASM groups. Sodium channel blocking ASMs included phenytoin, carbamazepine, lamotrigine, oxcarbazepine, lacosamide, zonisamide, topiramate, and valproic acid. A subgroup of predominant sodium channel blocking ASMs included phenytoin, carbamazepine, lamotrigine, oxcarbazepine, and lacosamide. Associations between the response of ASMs and single-nucleotide polymorphisms of SCN1A, SCN1B, SCN2A, and SCN9A were analyzed.

Results

Two hundred Taiwanese patients and 21 single-nucleotide polymorphisms among SCN1A, SCN1B, SCN2A, and SCN9A were evaluated. We found allele C of rs55742440 in SCN1B was statistically significantly associated with not achieving seizure-free with sodium channel blocking ASMs. For the predominant sodium channel blocking ASMs group, no SNPs were associated with the response of ASMs.

Conclusion

Single-nucleotide polymorphism in SCN1B was associated with the response to sodium channel blocking ASMs. This highlights the possibility that beta subunits may affect the function of sodium channels and resulted in different responsiveness to ASMs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02395-2.

Searching for a paradigm shift in the research on the epilepsies and associated neuropsychiatric comorbidities. From ancient historical knowledge to the challenge of contemporary systems complexity and emergent functions

In this review, we will discuss in four scenarios our challenges to offer possible solutions for the puzzle associated with the epilepsies and neuropsychiatric comorbidities. We need to recognize that (1) since quite old times, human wisdom was linked to the plural (distinct global places/cultures) perception of the Universe we are in, with deep respect for earth and nature. Plural ancestral knowledge was added with the scientific methods; however, their joint efforts are the ideal scenario; (2) human behavior is not different than animal behavior, in essence the product of Darwinian natural selection; knowledge of animal and human behavior are complementary; (3) the expression of human behavior follows the same rules that complex systems with emergent properties, therefore, we can measure events in human, clinical, neurobiological situations with complexity systems' tools; (4) we can use the semiology of epilepsies and comorbidities, their neural substrates, and potential treatments (including experimental/computational modeling, neurosurgical interventions), as a source and collection of integrated big data to predict with them (e.g.: machine/deep learning) diagnosis/prognosis, individualized solutions (precision medicine), basic underlying mechanisms and molecular targets. Once the group of symptoms/signals (with a myriad of changing definitions and interpretations over time) and their specific sequences are determined, in epileptology research and clinical settings, the use of modern and contemporary techniques such as neuroanatomical maps, surface electroencephalogram and stereoelectroencephalography (SEEG) and imaging (MRI, BOLD, DTI, SPECT/PET), neuropsychological testing, among others, are auxiliary in the determination of the best electroclinical hypothesis, and help design a specific treatment, usually as the first attempt, with available pharmacological resources. On top of ancient knowledge, currently known and potentially new antiepileptic drugs, alternative treatments and mechanisms are usually produced as a consequence of the hard, multidisciplinary, and integrated studies of clinicians, surgeons, and basic scientists, all over the world. The existence of pharmacoresistant patients, calls for search of other solutions, being along the decades the surgeries the most common interventions, such as resective procedures (i.e., selective or standard lobectomy, lesionectomy), callosotomy, hemispherectomy and hemispherotomy, added by vagus nerve stimulation (VNS), deep brain stimulation (DBS), neuromodulation, and more recently focal minimal or noninvasive ablation. What is critical when we consider the pharmacoresistance aspect with the potential solution through surgery, is still the pursuit of localization-dependent regions (e.g.: epileptogenic zone (EZ)), in order to decide, no matter how sophisticated are the brain mapping tools (EEG and MRI), the size and location of the tissue to be removed. Mimicking the semiology and studying potential neural mechanisms and molecular targets - by means of experimental and computational modeling - are fundamental steps of the whole process. Concluding, with the conjunction of ancient knowledge, coupled to critical and creative contemporary, scientific (not dogmatic) clinical/surgical, and experimental/computational contributions, a better world and of improved quality of life can be offered to the people with epilepsy and neuropsychiatric comorbidities, who are still waiting (as well as the scientists) for a paradigm shift in epileptology, both in the Basic Science, Computational, Clinical, and Neurosurgical Arenas. This article is part of the Special Issue "NEWroscience 2018".

Antiepileptogenesis and disease modification: Progress, challenges, and the path forward-Report of the Preclinical Working Group of the 2018 NINDS-sponsored antiepileptogenesis and disease modification workshop

Epilepsy is one of the most common chronic brain diseases and is often associated with cognitive, behavioral, or other medical conditions. The need for therapies that would prevent, ameliorate, or cure epilepsy and the attendant comorbidities is a priority for both epilepsy research and public health. In 2018, the National Institute of Neurological Disease and Stroke (NINDS) convened a workshop titled "Accelerating the Development of Therapies for Antiepileptogenesis and Disease Modification" that brought together preclinical and clinical investigators and industry and regulatory bodies' representatives to discuss and propose a roadmap to accelerate the development of antiepileptogenic (AEG) and disease-modifying (DM) new therapies. This report provides a summary of the discussions and proposals of the Preclinical Science working group. Highlights of the progress of collaborative preclinical research projects on AEG/DM of ongoing research initiatives aiming to improve infrastructure and translation to clinical trials are presented. Opportunities and challenges of preclinical epilepsy research, vis-à-vis clinical research, were extensively discussed, as they pertain to modeling of specific epilepsy types across etiologies and ages, the utilization of preclinical models in AG/DM studies, and the strategies and study designs, as well as on matters pertaining to transparency, data sharing, and reporting research findings. A set of suggestions on research initiatives, infrastructure, workshops, advocacy, and opportunities for expanding the borders of epilepsy research were discussed and proposed as useful initiatives that could help create a roadmap to accelerate and optimize preclinical translational AEG/DM epilepsy research.

Opportunities and challenges for microRNA-targeting therapeutics for epilepsy

Epilepsy is a common and serious neurological disorder characterised by recurrent spontaneous seizures. Frontline pharmacotherapy includes small-molecule antiseizure drugs that typically target ion channels and neurotransmitter systems, but these fail in 30% of patients and do not prevent either the development or progression of epilepsy. An emerging therapeutic target is microRNA (miRNA), small noncoding RNAs that negatively regulate sets of proteins. Their multitargeting action offers unique advantages for certain forms of epilepsy with complex underlying pathophysiology, such as temporal lobe epilepsy (TLE). miRNA can be inhibited by designed antisense oligonucleotides (ASOs; e.g., antimiRs). Here, we outline the prospects for miRNA-based therapies. We review design considerations for nucleic acid-based approaches and the challenges and next steps in developing therapeutic miRNA-targeting molecules for epilepsy.

CircUBQLN1 Promotes Proliferation but Inhibits Apoptosis and Oxidative Stress of Hippocampal Neurons in Epilepsy via the miR-155-Mediated SOX7 Upregulation

Circular RNAs (circRNAs) have key roles in a variety of neurological diseases, including epilepsy. This objective of this study was to perform the functional exploration and mechanism investigation of circRNA Ubiquilin1 (circUBQLN1) in epilepsy. Epilepsy cell model was established by the treatment of Mg²⁺-free in human neurons-hippocampal (HN-h) cells. The quantitative real-time polymerase chain reaction (qRT-PCR) was used for the expression analysis of circUBQLN1, linear-UBQLN1, microRNA-155 (miR-155), and sex-determining region Y-box 7 (SOX7). Proliferation detection was completed using Cell Counting Kit-8 (CCK-8) assay. Apoptosis analysis was conducted by flow cytometry and caspase-3 assay. Oxidative stress was assessed through determining the levels of superoxide dismutase (SOD) and malondialdehyde (MDA). Target analysis was performed by dual-luciferase reporter and RNA pull-down assays. SOX7 protein level was examined by Western blot. CircUBQLN1 was downregulated in epilepsy samples and Mg²⁺-free-induced cell model. Functional analysis in vitro suggested that circUBQLN1 overexpression facilitated proliferation but reduced apoptosis and oxidative stress in Mg²⁺-free-treated HN-h cells. Target analysis showed that circUBQLN1 acted as a miR-155 sponge and miR-155-targeted SOX7. Moreover, circUBQLN1 could combine with miR-155 to regulate the SOX7 expression. Reverted assays indicated that circUBQLN1 overexpression alleviated the Mg²⁺-free-induced nerve injury by sponging miR-155, and knockdown of SOX7 abrogated the protective function of in-miR-155 or circUBQLN1 in the Mg²⁺-free-treated HN-h cells. Our data revealed that circUBQLN1 prevented nerve injury in Mg²⁺-free-treated HN-h cells by regulating the miR-155/SOX7 axis, showing that circUBQLN1 might be used as a biomolecular target for the treatment of epilepsy.

Transcranial magnetic stimulation as a tool to understand genetic conditions associated with epilepsy

Advances in genetics may enable a deeper understanding of disease mechanisms and promote a shift to more personalised medicine in the epilepsies. At present, understanding of consequences of genetic variants mainly relies on preclinical functional work; tools for acquiring similar data from the living human brain are needed. Transcranial magnetic stimulation (TMS), in particular paired-pulse TMS protocols which depend on the function of cortical GABAergic interneuron networks, has the potential to become such a tool. For this report, we identified and reviewed 23 publications on TMS studies of cortical excitability and inhibition in 15 different genes or conditions relevant to epilepsy. Reduced short-interval intracortical inhibition (SICI) and reduced cortical silent period (CSP) duration were the most commonly reported findings, suggesting abnormal GABA_A - (SICI) or GABA_B ergic (CSP) signalling. For several conditions, these findings are plausible based on established evidence of involvement of the GABAergic system; for some others, they may inform future research around such mechanisms. Challenges of TMS include lack of complete understanding of the neural underpinnings of the measures used: hypotheses and analyses should be based on existing clinical and preclinical data. Further pitfalls include gathering sufficient numbers of participants, and the effect of confounding factors, especially medications. TMS-EEG is a unique perturbational technique to study the intrinsic properties of the cortex with excellent temporal resolution; while it has the potential to provide further information of use in interpreting effects of genetic variants, currently the links between measures and neurophysiology are less established. Despite these challenges, TMS is a tool with potential for elucidating the system-level in vivo functional consequences of genetic variants in people carrying genetic changes of interest, providing unique insights.

Early Increase in Cortical T2 Relaxation Is a Prognostic Biomarker for the Evolution of Severe Cortical Damage, but Not for Epileptogenesis, after Experimental Traumatic Brain Injury

Prognostic biomarkers for post-injury outcome are necessary for the development of neuroprotective and antiepileptogenic treatments for traumatic brain injury (TBI). We hypothesized that T₂ relaxation magnetic resonance imaging (MRI) predicts the progression of perilesional cortical pathology and epileptogenesis. The EPITARGET animal cohort used for MRI analysis included 120 adult male Sprague-Dawley rats with TBI induced by lateral fluid-percussion injury and 24 sham-operated controls. T₂ MRI was performed at days 2, 7, and 21 post-TBI. The lesioned cortex was outlined, and the T₂ value of each imaging voxel within the lesion area was scored using a five-grade pathology classification. Analysis of 1-month video-electroencephalography recordings initiated 5 months post-TBI indicated that 27% (31 of 114) of the animals with TBI developed epilepsy. Multiple linear regression analysis indicated that T₂-based classification of lesion volume at day 2 and day 7 post-TBI explained the necrotic lesion volume with greatly increased T₂ (>102 ms) at day 21 post-TBI (F_(13,103) = 52.5; p < 0.001; R² =  0.87; adjusted R² = 0.85). The volume of moderately increased (78-102 ms) T₂ at day 7 post-TBI predicted the evolution of large (>12 mm³) cortical lesions (area under the curve, 0.92; p < 0.001; cutoff, 1.9 mm³; false positive rate, 0.10; true positive rate, 0.62). Logistic regression analysis, however, showed that the different severities of T₂ lesion volumes at days 2, 7, and 21 post-TBI did not explain the development of epilepsy (χ²_(18,95) = 18.4; p = 0.427). In addition, the location of the T₂ abnormality within the cortex did not correlate with epileptogenesis. A single measurement of T₂ relaxation MRI in the acute post-TBI phase is useful for identifying post-TBI subjects at highest risk of developing large cortical lesions, and thus, in the greatest need of neuroprotective therapies after TBI, but not the development of post-traumatic epilepsy.

From Genetic Testing to Precision Medicine in Epilepsy

Epilepsy includes a number of medical conditions with recurrent seizures as common denominator. The large number of different syndromes and seizure types as well as the highly variable inter-individual response to the therapies makes management of this condition often challenging. In the last two decades, a genetic etiology has been revealed in more than half of all epilepsies and single gene defects in ion channels or neurotransmitter receptors have been associated with most inherited forms of epilepsy, including some focal and lesional forms as well as specific epileptic developmental encephalopathies. Several genetic tests are now available, including targeted assays up to revolutionary tools that have made sequencing of all coding (whole exome) and non-coding (whole genome) regions of the human genome possible. These recent technological advances have also driven genetic discovery in epilepsy and increased our understanding of the molecular mechanisms of many epileptic disorders, eventually providing targets for precision medicine in some syndromes, such as Dravet syndrome, pyroxidine-dependent epilepsy, and glucose transporter 1 deficiency. However, these examples represent a relatively small subset of all types of epilepsy, and to date, precision medicine in epilepsy has primarily focused on seizure control, and other clinical aspects, such as neurodevelopmental and neuropsychiatric comorbidities, have yet been possible to address. We herein summarize the most recent advances in genetic testing and provide up-to-date approaches for the choice of the correct test for some epileptic disorders and tailored treatments that are already applicable in some monogenic epilepsies. In the next years, the most probably scenario is that epilepsy treatment will be very different from the currently almost empirical approach, eventually with a "precision medicine" approach applicable on a large scale.

[Psychometric properties of the Stigma Scale of Epilepsy]

AIM

To assess the psychometric properties of the Stigma Scale of Epilepsy, a short simple to complete questionnaire to quickly and reliably determine the presence and the level of perceived stigma in a particular patient, as well as to assess the prevalence, socio-demographic, clinical and socio-psychological factors associated with this phenomenon.

MATERIAL AND METHODS

The study included 398 patients with epilepsy. Exploratory (EFA) and confirmatory factor analysis (CFA) were used to assess the psychometric characteristics of the scale.

RESULTS AND CONCLUSION

The EFA showed a two-factor scale structure explaining 57.25% of the variance. Values of GFI 0.948, CFI 0.927 and RMSEA 0.057 after the data correction show a good conformity of the model to the empirical data. Cronbach's alpha coefficient was 0.862 for the scale, 0.815 for factor 1, 0.809 for factor 2, which indicates a high consistency of both the entire scale and its subscales. The Russian-language variant of the Stigma Scale of Epilepsy is a short, economical to use tool with good psychometric properties for assessing perceived stigma in patients with epilepsy.