Blood biomarkers in epilepsy

Neurofilament light chain and glial fibrillary acidic protein as diagnostic and prognostic biomarkers in epileptic seizures and epilepsy: A systematic review

Epileptology - with epilepsy as one of the most common neurological diseases - has an urgent need for easily accessible biomarkers to improve diagnosis, prognosis and therapeutic monitoring. Neurofilament light chain (NfL) and Glial Fibrillary Acidic Protein (GFAP) have emerged as promising fluid biomarkers in various neurological disorders. Their potential role in epileptic seizures and epilepsy remains largely unexplored. To assess the current state of research on this topic we comprehensively searched the published literature for studies on GFAP and/or NfL in cerebrospinal fluid and/or blood in adult humans with epileptic seizures, status epilepticus or epilepsy (last data base search on 10th of May 2024). We identified a total of 2285 publications of which 19 fulfilled our search criteria. The studies targeted various outcomes such as prognosis in status epilepticus, differentiation of seizure semiology and etiology, differentiation of epileptic seizures from non-epileptic conditions, prediction of epilepsy in autoimmune epilepsy, after a stroke or after a first unprovoked seizure, the role of the time interval from seizure to sampling, the association with disease duration as well as seizure frequency and the influence of seizure suppressing medication. The results are heterogeneous but indicate promising applications for both NfL and GFAP in diagnosis and prognostication of patients with epileptic seizures and epilepsy. In the present review we summarize the current evidence, future perspectives, but also limitations, of NfL and GFAP as fluid biomarkers in epilepsy and epileptic seizures.

The role of ubiquitin C-terminal hydrolase (UCH-L1) and protein S100B in differentiating patients with epileptic and psychogenic non-epileptic seizures - Pilot study

OBJECTIVE

Psychogenic non-epileptic seizures (PNES) are functional neurological disorders that are often misdiagnosed and treated as epileptic seizures (ES). Video-electroencephalography (v-EEG) is the gold standard for differentiating ES from PNES. However, blood biomarkers provide a faster and more accessible methodology, particularly for unwitnessed events. Ubiquitin C-terminal hydrolase L1 (UCH-L1) and protein S100B are key biomarkers released following neuronal and glial damage. Previous experimental and clinical studies have shown increased postictal serum and cerebrospinal fluid (CSF) levels of UCH-L1 and S100B in patients with ES.

METHODS

This prospective cohort pilot study compared postictal serum levels of UCH-L1 and S100B proteins in subjects with ES to those with PNES, aiming to identify specific biomarkers for distinguishing these conditions. To exclude confounding factors, the inclusion criteria required normal magnetic resonance (MR) findings of the brain. Strict timing of blood sampling and v-EEG monitoring were used for diagnosing PNES. The study included 32 subjects with epilepsy, 36 with PNES, and 30 healthy controls.

RESULTS

A significant difference in postictal UCH-L1 levels was observed among the groups. Subjects with ES had significantly higher postictal UCH-L1 levels (pg/mL) compared to those with PNES (p = 0.049) and healthy controls (p = 0.029). No significant differences were found between PNES subjects and healthy controls (p = 0.756). Postictal protein S100B levels did not differ significantly between the groups (p = 0.515).

SIGNIFICANCE

This study confirms the potential of postictal UCH-L1 levels as a biomarker for distinguishing ES from PNES. However, it also raises questions about the utility of protein S100B as a biomarker in epilepsy. Given the pilot nature of this study, UCH-L1 cannot yet be adopted for clinical use due to the small sample size, as statistical significance may have been driven by a subset of eight patients.

PLAIN LANGUAGE SUMMARY

This study evaluated two potential biomarkers, UCH-L1 and S100B, to differentiate ES from PNES in clinical practice. Our findings showed elevated postictal UCH-L1 levels in subjects with epilepsy compared to those with PNES, while no significant differences in S100B levels were observed among the groups.

Urinary Metabolic Profiling During Epileptogenesis in Rat Model of Lithium-Pilocarpine-Induced Temporal Lobe Epilepsy

Background/Objectives: Temporal lobe epilepsy (TLE) often develops following an initial brain injury, where specific triggers lead to epileptogenesis-a process transforming a healthy brain into one prone to spontaneous, recurrent seizures. Although electroencephalography (EEG) remains the primary diagnostic tool for epilepsy, it cannot predict the risk of epilepsy after brain injury. This limitation highlights the need for biomarkers, particularly those measurable in peripheral samples, to assess epilepsy risk. This study investigated urinary metabolites in a rat model of TLE to identify biomarkers that track epileptogenesis progression across the acute, latent, and chronic phases and elucidate the underlying mechanisms. Methods: Status epilepticus (SE) was induced in rats using repeated intraperitoneal injections of lithium chloride-pilocarpine hydrochloride. Urine samples were collected 48 h, 1 week, and 6 weeks after SE induction. Nuclear magnetic resonance spectrometry was used for metabolomic analysis, and statistical evaluations were performed using MetaboAnalyst 6.0. Differences between epileptic and control groups were represented using the orthogonal partial least squares discriminant analysis (OPLS-DA) model. Volcano plot analysis identified key metabolic changes, applying a fold-change threshold of 1.5 and a p-value < 0.05. Results: The acute phase exhibited elevated levels of acetic acid, dihydrothymine, thymol, and trimethylamine, whereas glycolysis and tricarboxylic acid cycle metabolites, including pyruvic and citric acids, were reduced. Both the acute and latent phases showed decreased theobromine, taurine, and allantoin levels, with elevated 1-methylhistidine in the latent phase. The chronic phase exhibited reductions in pimelic acid, tiglylglycine, D-lactose, and xanthurenic acid levels. Conclusions: These findings highlight stage-specific urinary metabolic changes in TLE, suggesting distinct metabolites as biomarkers for epileptogenesis and offering insights into the mechanisms underlying SE progression.

High-resolution multimodal profiling of human epileptic brain activity via explanted depth electrodes

The availability and integration of electrophysiological and molecular data from the living brain is critical in understanding and diagnosing complex human disease. Intracranial stereo electroencephalography (SEEG) electrodes used for identifying the seizure focus in patients with epilepsy could enable the integration of such multimodal data. Here, we report multimodal profiling of epileptic brain activity via explanted depth electrodes (MoPEDE), a method that recovers extensive protein-coding transcripts, including cell type markers, DNA methylation, and short variant profiles from explanted SEEG electrodes matched with electrophysiological and radiological data allowing for high-resolution reconstructions of brain structure and function. We found gene expression gradients that corresponded with the neurophysiology-assigned epileptogenicity index but also outlier molecular fingerprints in some electrodes, potentially indicating seizure generation or propagation zones not detected during electroclinical assessments. Additionally, we identified DNA methylation profiles indicative of transcriptionally permissive or restrictive chromatin states and SEEG-adherent differentially expressed and methylated genes not previously associated with epilepsy. Together, these findings validate that RNA profiles and genome-wide epigenetic data from explanted SEEG electrodes offer high-resolution surrogate molecular landscapes of brain activity. The MoPEDE approach has the potential to enhance diagnostic decisions and deepen our understanding of epileptogenic network processes in the human brain.

Circulating microRNAs as Biomarkers of Various Forms of Epilepsy

Background: Epilepsy is a group of disorders characterized by a cluster of clinical and EEG signs leading to the formation of abnormal synchronous excitation of neurons in the brain. It is one of the most common neurological disorders worldwide; and is characterized by aberrant expression patterns; both at the level of matrix transcripts and at the level of regulatory RNA sequences. Aberrant expression of a number of microRNAs can mark a particular epileptic syndrome; which will improve the quality of differential diagnosis. Materials and Methods: In this work; the expression profile of six microRNAs was analyzed: hsa-miR-106b-5p; hsa-miR-134-5p; hsa-miR-122-5p; hsa-miR-132-3p; hsa-miR-155-5p; and hsa-miR-206-5p in the blood plasma of patients suffering from temporal lobe epilepsy (n = 52) and juvenile myoclonic epilepsy (n = 42); n-amount of participants; in comparison with healthy volunteers. The expression analysis was carried out using RT-PCR. Mathematical processing of the data was carried out according to the Livak method. Results: A statistically significant change in the expression of hsa-miR-106b-5p; hsa-miR-134-5p; hsa-miR-122-5p; and hsa-miR-132-3p was found. An increase in the expression of hsa-miR-134-5p and hsa-miR-122-5p was registered in the group of patients with temporal lobe epilepsy compared to the control; as well as an increase in the expression of hsa-miR-132-3p and hsa-miR-106b-5p in the juvenile myoclonic epilepsy group compared to the control. hsa-miR-122-5p; 106b-5p; 132-3p are also able to discriminate groups with different syndromes. Additionally; a number of microRNAs are able to discriminate patients with drug-resistant and drug-sensitive forms of epilepsy from the control; as well as patients with hippocampal sclerosis and patients without hippocampal sclerosis from the control. Conclusion. Our data allow us to propose these microRNAs as plasma biomarkers of various epileptic syndromes.

Brain injury biomarkers and applications in neurological diseases

ABSTRACT

Neurological diseases are a major health concern, and brain injury is a typical pathological process in various neurological disorders. Different biomarkers in the blood or the cerebrospinal fluid are associated with specific physiological and pathological processes. They are vital in identifying, diagnosing, and treating brain injuries. In this review, we described biomarkers for neuronal cell body injury (neuron-specific enolase, ubiquitin C-terminal hydrolase-L1, αII-spectrin), axonal injury (neurofilament proteins, tau), astrocyte injury (S100β, glial fibrillary acidic protein), demyelination (myelin basic protein), autoantibodies, and other emerging biomarkers (extracellular vesicles, microRNAs). We aimed to summarize the applications of these biomarkers and their related interests and limits in the diagnosis and prognosis for neurological diseases, including traumatic brain injury, status epilepticus, stroke, Alzheimer's disease, and infection. In addition, a reasonable outlook for brain injury biomarkers as ideal detection tools for neurological diseases is presented.

Plasma proteomics in epilepsy: Network-based identification of proteins associated with seizures

PURPOSE

Identification of potential biomarkers of seizures.

METHODS

In this exploratory study, we quantified plasma protein intensities in 15 patients with recent seizures compared to 15 patients with long-standing seizure freedom. Using TMT-based proteomics we found fifty-one differentially expressed proteins.

RESULTS

Network analyses including co-expression networks and protein-protein interaction networks, using the STRING database, followed by network centrality and modularity analyses revealed 22 protein modules, with one module showing a significant association with seizures. The protein-protein interaction network centered around this module identified a subnetwork of 125 proteins, grouped into four clusters. Notably, one cluster (mainly enriching inflammatory pathways and Gene Ontology terms) demonstrated the highest enrichment of known epilepsy-related genes.

CONCLUSION

Overall, our network-based approach identified a protein module linked with seizures. The module contained known markers of epilepsy and inflammation. The results also demonstrate the potential of network analysis in discovering new biomarkers for improved epilepsy management.

Elevated plasma neurofilament light and glial fibrillary acidic protein in epilepsy versus nonepileptic seizures and nonepileptic disorders

OBJECTIVE

Research suggests that recurrent seizures may lead to neuronal injury. Neurofilament light chain protein (NfL) and glial fibrillary acidic protein (GFAP) levels increase in cerebrospinal fluid and blood in response to neuroaxonal damage, and they have been hypothesized as potential biomarkers for epilepsy. We examined plasma NfL and GFAP levels and their diagnostic utility in differentiating patients with epilepsy from those with psychogenic nonepileptic seizures (PNES) and other nonepileptic disorders.

METHODS

We recruited consecutive adults admitted for video-electroencephalographic monitoring and formal neuropsychiatric assessment. NfL and GFAP levels were quantified and compared between different patient groups and an age-matched reference cohort (n = 1926) and correlated with clinical variables in patients with epilepsy.

RESULTS

A total of 138 patients were included, of whom 104 were diagnosed with epilepsy, 22 with PNES, and 12 with other conditions. Plasma NfL and GFAP levels were elevated in patients with epilepsy compared to PNES, adjusted for age and sex (NfL p = .04, GFAP p = .04). A high proportion of patients with epilepsy (20%) had NfL levels above the 95th age-matched percentile compared to the reference cohort (5%). NfL levels above the 95th percentile of the reference cohort had a 95% positive predictive value for epilepsy. Patients with epilepsy who had NfL levels above the 95th percentile were younger than those with lower levels (37.5 vs. 43.8 years, p = .03).

SIGNIFICANCE

An elevated NfL or GFAP level in an individual patient may support an underlying epilepsy diagnosis, particularly in younger adults, and cautions against a diagnosis of PNES alone. Further examination of the association between NfL and GFAP levels and specific epilepsy subtypes or seizure characteristics may provide valuable insights into disease heterogeneity and contribute to the refinement of diagnosis, understanding pathophysiological mechanisms, and formulating treatment approaches.

Application of Mozart's Sonata for Two Pianos in D Major in Children with Epilepsy and Effect of Acoustic Quality on Epileptic Discharges

BACKGROUND

Mozart's Sonata for Two Pianos in D Major (K448) is a classic double piano work. This study investigated its effect on children with epilepsy (EP) and analyzed the changes in electroencephalography (EEG) among children on the basis of acoustic quality.

METHODS

The clinical data of 150 children with EP in the Affiliated Hospital (Group) of Putian University from March 2020 to March 2023 were retrospectively analyzed. They were divided into group A (n = 73, antiepileptic drug therapy) and group B (n = 77, antiepileptic drug therapy + Mozart K448) in accordance with the treatment methods. The seizure frequency, frequency of epileptic discharges (EDs), and Quality of Life in Childhood Epilepsy Questionnaire-16 in both groups were compared before and after treatment. The changes in EEG before, during, and after music appreciation were observed. The effects of the acoustic characteristics (rhythm, root mean square value, roughness, and spectral flux) of Mozart K448 on EDs in children were explored.

RESULTS

After treatment, group A had a higher seizure frequency (P < 0.001), a higher frequency of EDs (P < 0.05), and significantly lower scores of cognition and emotion than group B (P < 0.001), without significant difference in the scores of social function and physical function (P > 0.05). The frequency of EDs before music appreciation was significantly higher than that during music appreciation (P < 0.01). Spearman correlation analysis showed that the rhythm, spectral flux, and roughness in Mozart K488 were related to the decrease in EDs among children with EP (P < 0.001).

CONCLUSION

This study confirmed the application effect of Mozart K448 in children with EP. Mozart K448 can decrease the seizure frequency, reduce the ED occurrence, and improve the quality of life. The acoustic characteristics of K448 may be the reason for improving EP in children.

A Systematic Review of the Predictive and Diagnostic Uses of Neuroinflammation Biomarkers for Epileptogenesis

A central role for neuroinflammation in epileptogenesis has recently been suggested by several investigations. This systematic review explores the role of inflammatory mediators in epileptogenesis, its association with seizure severity, and its correlation with drug-resistant epilepsy (DRE). The study analysed articles published in JCR journals from 2019 to 2024. The search strategy comprised the MESH, free terms of "Neuroinflammation", and selective searches for the following single biomarkers that had previously been selected from the relevant literature: "High mobility group box 1/HMGB1", "Toll-Like-Receptor 4/TLR-4", "Interleukin-1/IL-1", "Interleukin-6/IL-6", "Transforming growth factor beta/TGF-β", and "Tumour necrosis factor-alpha/TNF-α". These queries were all combined with the MESH terms "Epileptogenesis" and "Epilepsy". We found 243 articles related to epileptogenesis and neuroinflammation, with 356 articles from selective searches by biomarker type. After eliminating duplicates, 324 articles were evaluated, with 272 excluded and 55 evaluated by the authors. A total of 21 articles were included in the qualitative evaluation, including 18 case-control studies, 2 case series, and 1 prospective study. As conclusion, this systematic review provides acceptable support for five biomarkers, including TNF-α and some of its soluble receptors (sTNFr2), HMGB1, TLR-4, CCL2 and IL-33. Certain receptors, cytokines, and chemokines are examples of neuroinflammation-related biomarkers that may be crucial for the early diagnosis of refractory epilepsy or may be connected to the control of epileptic seizures. Their value will be better defined by future studies.

Nanomedicine revolutionizes epilepsy treatment: overcoming therapeutic hurdles with nanoscale solutions

INTRODUCTION

Epilepsy, a prevalent neurodegenerative disorder, profoundly impacts the physical and mental well-being of millions globally. Historically, antiseizure drugs (ASDs) have been the primary treatment modality. However, despite the introduction of novel ASDs in recent decades, a significant proportion of patients still experiences uncontrolled seizures.

AREAS COVERED

The rapid advancement of nanomedicine in recent years has enabled precise targeting of the brain, thereby enhancing therapeutic efficacy for brain diseases, including epilepsy.

EXPERT OPINION

Nanomedicine holds immense promise in epilepsy treatment, including but not limited to enhancing drug solubility and stability, improving drug across blood-brain barrier, overcoming resistance, and reducing side effects, potentially revolutionizing clinical management. This paper provides a comprehensive overview of current epilepsy treatment modalities and highlights recent advancements in nanomedicine-based drug delivery systems for epilepsy control. We discuss the diverse strategies used in developing novel nanotherapies, their mechanisms of action, and the potential advantages they offer compared to traditional treatment methods.

The role of angiotensin receptor blockers in treating epilepsy: a review

Epilepsy is a chronic brain disease with a global prevalence of 70 million people. According to the World Health Organization, roughly 5 million new cases are diagnosed every year. Anti-seizure drugs are the treatment of choice. However, in roughly one third of the patients, these drugs fail to produce the desired effect. As a result, finding novel treatments for epilepsy becomes inevitable. Recently, angiotensin receptor blockers have been proposed as a treatment to reduce the over-excitation of neurons in epilepsy. For this purpose, we conducted a review using Medline/PubMed and Google Scholar using the relevant search terms and extracted the relevant data in a table. Our review suggests that this novel approach has a very high potential to treat epilepsy, especially in those patients who fail to respond to conventional treatment options. However, more extensive and human-based trials should be conducted to reach a decisive conclusion. Nevertheless, the use of ARBs in patients with epilepsy should be carefully monitored keeping the adverse effects in mind.

Virus-Induced Epilepsy vs. Epilepsy Patients Acquiring Viral Infection: Unravelling the Complex Relationship for Precision Treatment

The intricate relationship between viruses and epilepsy involves a bidirectional interaction. Certain viruses can induce epilepsy by infecting the brain, leading to inflammation, damage, or abnormal electrical activity. Conversely, epilepsy patients may be more susceptible to viral infections due to factors, such as compromised immune systems, anticonvulsant drugs, or surgical interventions. Neuroinflammation, a common factor in both scenarios, exhibits onset, duration, intensity, and consequence variations. It can modulate epileptogenesis, increase seizure susceptibility, and impact anticonvulsant drug pharmacokinetics, immune system function, and brain physiology. Viral infections significantly impact the clinical management of epilepsy patients, necessitating a multidisciplinary approach encompassing diagnosis, prevention, and treatment of both conditions. We delved into the dual dynamics of viruses inducing epilepsy and epilepsy patients acquiring viruses, examining the unique features of each case. For virus-induced epilepsy, we specify virus types, elucidate mechanisms of epilepsy induction, emphasize neuroinflammation's impact, and analyze its effects on anticonvulsant drug pharmacokinetics. Conversely, in epilepsy patients acquiring viruses, we detail the acquired virus, its interaction with existing epilepsy, neuroinflammation effects, and changes in anticonvulsant drug pharmacokinetics. Understanding this interplay advances precision therapies for epilepsy during viral infections, providing mechanistic insights, identifying biomarkers and therapeutic targets, and supporting optimized dosing regimens. However, further studies are crucial to validate tools, discover new biomarkers and therapeutic targets, and evaluate targeted therapy safety and efficacy in diverse epilepsy and viral infection scenarios.

Serum biomarkers in patients with drug-resistant epilepsy: a proteomics-based analysis

Objective

To investigate the serum biomarkers in patients with drug-resistant epilepsy (DRE).

Methods

A total of 9 DRE patients and 9 controls were enrolled. Serum from DRE patients was prospectively collected and analyzed for potential serum biomarkers using TMT18-labeled proteomics. After fine quality control, bioinformatics analysis was conducted to find differentially expressed proteins. Pathway enrichment analysis identified some biological features shared by differential proteins. Protein-protein interaction (PPI) network analysis was further performed to discover the core proteins.

Results

A total of 117 serum differential proteins were found in our study, of which 44 were revised upwards and 73 downwards. The up-regulated proteins mainly include UGGT2, PDIA4, SEMG1, KIAA1191, CCT7 etc. and the down-regulated proteins mainly include ROR1, NIF3L1, ITIH4, CFP, COL11A2 etc. Pathway enrichment analysis identified that the upregulated proteins were mainly enriched in processes such as immune response, extracellular exosome, serine-type endopeptidase activity and complement and coagulation cascades, and the down-regulated proteins were enriched in signal transduction, extracellular exosome, zinc/calcium ion binding and metabolic pathways. PPI network analysis revealed that the core proteins nodes include PRDX6, CAT, PRDX2, SOD1, PARK7, GSR, TXN, ANXA1, HINT1, and S100A8 etc.

Conclusion

The discovery of these differential proteins enriched our understanding of serum biomarkers in patients with DRE and potentially provides guidance for future targeted therapy.

Matrix Metalloproteinase-9 Contributes to Epilepsy Development after Ischemic Stroke in Mice

Epilepsy, a neurological disorder affecting over 50 million individuals globally, is characterized by an enduring predisposition and diverse consequences, both neurobiological and social. Acquired epilepsy, constituting 30% of cases, often results from brain-damaging injuries like ischemic stroke. With one third of epilepsy cases being resistant to existing drugs and without any preventive therapeutics for epileptogenesis, identifying anti-epileptogenic targets is crucial. Stroke being a leading cause of acquired epilepsy, particularly in the elderly, prompts the need for understanding post-stroke epileptogenesis. Despite the challenges in studying stroke-evoked epilepsy in rodents due to poor long-term survival rates, in this presented study the use of an animal care protocol allowed for comprehensive investigation. We highlight the role of matrix metalloproteinase-9 (MMP-9) in post-stroke epileptogenesis, emphasizing MMP-9 involvement in mouse models and its potential as a therapeutic target. Using a focal Middle Cerebral Artery occlusion model, this study demonstrates MMP-9 activation following ischemia, influencing susceptibility to seizures. MMP-9 knockout reduces epileptic features, while overexpression exacerbates them. The findings show that MMP-9 is a key player in post-stroke epileptogenesis, presenting opportunities for future therapies and expanding our understanding of acquired epilepsy.

Aerobic exercise alters DNA hydroxymethylation levels in an experimental rodent model of temporal lobe epilepsy

The therapeutic potential of aerobic exercise in mitigating seizures and cognitive issues in temporal lobe epilepsy (TLE) is recognized, yet the underlying mechanisms are not well understood. Using a rodent TLE model induced by Kainic acid (KA), we investigated the impact of a single bout of exercise (i.e., acute) or 4 weeks of aerobic exercise (i.e., chronic). Blood was processed for epilepsy-associated serum markers, and DNA methylation (DNAme), and hippocampal area CA3 was assessed for gene expression levels for DNAme-associated enzymes. While acute aerobic exercise did not alter serum Brain-Derived Neurotrophic Factor (BDNF) or Interleukin-6 (IL-6), chronic exercise resulted in an exercise-specific decrease in serum BDNF and an increase in serum IL-6 levels in epileptic rats. Additionally, whole blood DNAme levels, specifically 5-hydroxymethylcytosine (5-hmC), decreased in epileptic animals following chronic exercise. Hippocampal CA3 5-hmC levels and ten-eleven translocation protein (TET1) expression mirrored these changes. Furthermore, immunohistochemistry analysis revealed that most 5-hmC changes in response to chronic exercise were neuron-specific within area CA3 of the hippocampus. Together, these findings suggest that DNAme mechanisms in the rodent model of TLE are responsive to chronic aerobic exercise, with emphasis on neuronal 5-hmC DNAme in the epileptic hippocampus.

Complexity in Genetic Epilepsies: A Comprehensive Review

Epilepsy is a highly prevalent neurological disorder, affecting between 5-8 per 1000 individuals and is associated with a lifetime risk of up to 3%. In addition to high incidence, epilepsy is a highly heterogeneous disorder, with variation including, but not limited to the following: severity, age of onset, type of seizure, developmental delay, drug responsiveness, and other comorbidities. Variable phenotypes are reflected in a range of etiologies including genetic, infectious, metabolic, immune, acquired/structural (resulting from, for example, a severe head injury or stroke), or idiopathic. This review will focus specifically on epilepsies with a genetic cause, genetic testing, and biomarkers in epilepsy.

Neurofilament light chain: A possible fluid biomarker in the intrahippocampal kainic acid mouse model for chronic epilepsy?

OBJECTIVE

In the management of epilepsy, there is an ongoing quest to discover new biomarkers to improve the diagnostic process, the monitoring of disease progression, and the evaluation of treatment responsiveness. In this regard, biochemical traceability in biofluids is notably absent in contrast to other diseases. In the present preclinical study, we investigated the potential of neurofilament light chain (NfL) as a possible diagnostic and response fluid biomarker for epilepsy.

METHODS

We gained insights into NfL levels during the various phases of the intrahippocampal kainic acid mouse model of temporal lobe epilepsy-namely, the status epilepticus (SE) and the chronic phase with spontaneous seizures. To this end, NfL levels were determined directly in the cerebral interstitial fluid (ISF) with cerebral open flow microperfusion as sampling technique, as well as in cerebrospinal fluid (CSF) and plasma. Lastly, we assessed whether NfL levels diminished upon curtailing SE with diazepam and ketamine.

RESULTS

NfL levels are higher during SE in both cerebral ISF and plasma in kainic acid-treated mice compared to sham-injected mice. Additionally, ISF and plasma NfL levels are lower in mice treated with diazepam and ketamine to stop SE compared with the vehicle-treated mice. In the chronic phase with spontaneous seizures, higher NfL levels could only be detected in ISF and CSF samples, and not in plasma. No correlations could be found between NfL levels and seizure burden, nor with immunohistological markers for neurodegeneration/inflammation.

SIGNIFICANCE

Our findings demonstrate the translational potential of NfL as a blood-based fluid biomarker for SE. This is less evident for chronic epilepsy, as in this case higher NfL levels could only be detected in ISF and CSF, and not in plasma, acknowledging the invasive nature of CSF sampling in chronic epilepsy follow-up.

The S100B Protein: A Multifaceted Pathogenic Factor More Than a Biomarker

S100B is a calcium-binding protein mainly concentrated in astrocytes in the nervous system. Its levels in biological fluids are recognized as a reliable biomarker of active neural distress, and more recently, mounting evidence points to S100B as a Damage-Associated Molecular Pattern molecule, which, at high concentration, triggers tissue reactions to damage. S100B levels and/or distribution in the nervous tissue of patients and/or experimental models of different neural disorders, for which the protein is used as a biomarker, are directly related to the progress of the disease. In addition, in experimental models of diseases such as Alzheimer's and Parkinson's diseases, amyotrophic lateral sclerosis, multiple sclerosis, traumatic and vascular acute neural injury, epilepsy, and inflammatory bowel disease, alteration of S100B levels correlates with the occurrence of clinical and/or toxic parameters. In general, overexpression/administration of S100B worsens the clinical presentation, whereas deletion/inactivation of the protein contributes to the amelioration of the symptoms. Thus, the S100B protein may be proposed as a common pathogenic factor in different disorders, sharing different symptoms and etiologies but appearing to share some common pathogenic processes reasonably attributable to neuroinflammation.

Combined transcriptomics and proteomics forecast analysis for potential biomarker in the acute phase of temporal lobe epilepsy

Background

Temporal lobe epilepsy (TLE) is a common chronic episodic illness of the nervous system. However, the precise mechanisms of dysfunction and diagnostic biomarkers in the acute phase of TLE are uncertain and hard to diagnose. Thus, we intended to qualify potential biomarkers in the acute phase of TLE for clinical diagnostics and therapeutic purposes.

Methods

An intra-hippocampal injection of kainic acid was used to induce an epileptic model in mice. First, with a TMT/iTRAQ quantitative labeling proteomics approach, we screened for differentially expressed proteins (DEPs) in the acute phase of TLE. Then, differentially expressed genes (DEGs) in the acute phase of TLE were identified by linear modeling on microarray data (limma) and weighted gene co-expression network analysis (WGCNA) using the publicly available microarray dataset GSE88992. Co-expressed genes (proteins) in the acute phase of TLE were identified by overlap analysis of DEPs and DEGs. The least absolute shrinkage and selection operator (LASSO) regression and support vector machine recursive feature elimination (SVM-RFE) algorithms were used to screen Hub genes in the acute phase of TLE, and logistic regression algorithms were applied to develop a novel diagnostic model for the acute phase of TLE, and the sensitivity of the diagnostic model was validated using receiver operating characteristic (ROC) curves.

Results

We screened a total of 10 co-expressed genes (proteins) from TLE-associated DEGs and DEPs utilizing proteomic and transcriptome analysis. LASSO and SVM-RFE algorithms for machine learning were applied to identify three Hub genes: Ctla2a, Hapln2, and Pecam1. A logistic regression algorithm was applied to establish and validate a novel diagnostic model for the acute phase of TLE based on three Hub genes in the publicly accessible datasets GSE88992, GSE49030, and GSE79129.

Conclusion

Our study establishes a reliable model for screening and diagnosing the acute phase of TLE that provides a theoretical basis for adding diagnostic biomarkers for TLE acute phase genes.