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Epilepsy is one of the most common neurological disorders, yet its pathophysiology is poorly understood due to the high complexity of affected neuronal circuits. To identify dysfunctional neuronal subtypes underlying seizure activity in the human brain, we have performed single-nucleus transcriptomics analysis of >110,000 neuronal transcriptomes derived from temporal cortex samples of multiple temporal lobe epilepsy and non-epileptic subjects. We found that the largest transcriptomic changes occur in distinct neuronal subtypes from several families of principal neurons (L5-6_Fezf2 and L2-3_Cux2) and GABAergic interneurons (Sst and Pvalb), whereas other subtypes in the same families were less affected. Furthermore, the subtypes with the largest epilepsy-related transcriptomic changes may belong to the same circuit, since we observed coordinated transcriptomic shifts across these subtypes. Glutamate signaling exhibited one of the strongest dysregulations in epilepsy, highlighted by layer-wise transcriptional changes in multiple glutamate receptor genes and strong upregulation of genes coding for AMPA receptor auxiliary subunits. Overall, our data reveal a neuronal subtype-specific molecular phenotype of epilepsy. The pathophysiology of epilepsy is unclear. Here, the authors present single-nuclei transcriptomic profiling of human temporal lobe epilepsy from patients. They identified epilepsy-associated neuronal subtypes, and a panel of dysregulated genes, predicting neuronal circuits contributing to epilepsy.

Neuronal dysfunction due to iron accumulation in conjunction with reactive oxygen species (ROS) could represent an important, yet underappreciated, component of the epileptogenic process. However, to date, alterations in iron metabolism in the epileptogenic brain have not been addressed in detail. Iron-related neuropathology and antioxidant metabolic processes were investigated in resected brain tissue from patients with temporal lobe epilepsy and hippocampal sclerosis (TLE-HS), post-mortem brain tissue from patients who died after status epilepticus (SE) as well as brain tissue from the electrically induced SE rat model of TLE. Magnetic susceptibility of the presumed seizure-onset zone from three patients with focal epilepsy was compared during and after seizure activity. Finally, the cellular effects of iron overload were studied in vitro using an acute mouse hippocampal slice preparation and cultured human fetal astrocytes. While iron-accumulating neurons had a pyknotic morphology, astrocytes appeared to acquire iron-sequestrating capacity as indicated by prominent ferritin expression and iron retention in the hippocampus of patients with SE or TLE. Interictal to postictal comparison revealed increased magnetic susceptibility in the seizure-onset zone of epilepsy patients. Post-SE rats had consistently higher hippocampal iron levels during the acute and chronic phase (when spontaneous recurrent seizures are evident). In vitro, in acute slices that were exposed to iron, neurons readily took up iron, which was exacerbated by induced epileptiform activity. Human astrocyte cultures challenged with iron and ROS increased their antioxidant and iron-binding capacity, but simultaneously developed a pro-inflammatory phenotype upon chronic exposure. These data suggest that seizure-mediated, chronic neuronal iron uptake might play a role in neuronal dysfunction/loss in TLE-HS. On the other hand, astrocytes sequester iron, specifically in chronic epilepsy. This function might transform astrocytes into a highly resistant, pro-inflammatory phenotype potentially contributing to pro-epileptogenic inflammatory processes.

Acute seizures after a severe brain insult can often lead to epilepsy and cognitive impairment. Aberrant hippocampal neurogenesis follows the insult but the role of adult-generated neurons in the development of chronic seizures or associated cognitive deficits remains to be determined. Here we show that the ablation of adult neurogenesis before pilocarpine-induced acute seizures in mice leads to a reduction in chronic seizure frequency. We also show that ablation of neurogenesis normalizes epilepsy-associated cognitive deficits. Remarkably, the effect of ablating adult neurogenesis before acute seizures is long lasting as it suppresses chronic seizure frequency for nearly 1 year. These findings establish a key role of neurogenesis in chronic seizure development and associated memory impairment and suggest that targeting aberrant hippocampal neurogenesis may reduce recurrent seizures and restore cognitive function following a pro-epileptic brain insult. Aberrant hippocampal neurogenesis often occurs after acute seizures that produce epilepsy and cognitive impairment but the role of neurogenesis in the development of epilepsy is unclear. Here the authors suppress adult neurogenesis in mice preceding seizures and show that it reduces subsequent chronic seizure frequency and epilepsy-associated cognitive decline.

Introduction In this report, we aim to describe the design for the randomised controlled trial of Stereotactic electroencephalogram (EEG)-guided Radiofrequency Thermocoagulation versus Anterior Temporal Lobectomy for Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (STARTS). Mesial temporal lobe epilepsy (mTLE) is a classical subtype of temporal lobe epilepsy that often requires surgical intervention. Although anterior temporal lobectomy (ATL) remains the most popular treatment for mTLE, accumulating evidence has indicated that ATL can cause tetartanopia and memory impairments. Stereotactic EEG (SEEG)-guided radiofrequency thermocoagulation (RF-TC) is a non-invasive alternative associated with lower seizure freedom but greater preservation of neurological function. In the present study, we aim to compare the safety and efficacy of SEEG-guided RF-TC and classical ATL in the treatment of mTLE. Methods and analysis STARTS is a single-centre, two-arm, randomised controlled, parallel-group clinical trial. The study includes patients with typical mTLE over the age of 14 who have drug-resistant seizures for at least 2 years and have been determined via detailed evaluation to be surgical candidates prior to randomisation. The primary outcome measure is the cognitive function at the 1-year follow-up after treatment. Seizure outcomes, visual field abnormalities after surgery, quality of life, ancillary outcomes, and adverse events will also be evaluated at 1-year follow-up as secondary outcomes. Discussion SEEG-guided RF-TC for mTLE remains a controversial seizure outcome but has the advantage for cognitive and visual field protection. This is the first RCT studying cognitive outcomes and treatment results between SEEG-guided RF-TC and standard ATL for mTLE with hippocampal sclerosis. This study may provide higher levels of clinical evidence for the treatment of mTLE. Trial registration ClinicalTrials.gov NCT03941613 . Registered on May 8, 2019. The STARTS protocol has been registered on the US National Institutes of Health. The status of the STARTS was recruiting and the estimated study completion date was December 31, 2021.

The objective of this study was to explore the protective effects of hydroxy fullerenes (HFs) on cognitive function in rats with temporal lobe epilepsy (TLE) and to elucidate the underlying mechanisms. Eighteen Sprague-Dawley (SD) rats were randomly selected and administered pilocarpine (50 mg/kg) intraperitoneally to establish a TLE model, and were then randomly assigned to the TLE group and the TLE + HFs group. An additional nine SD rats were served as a normal control group (CON group). The Morris water maze (MWM) test was utilized to assess the spatial learning and memory capabilities of the rats. Nissl staining was employed to observe the survival neurons in the CA1 and CA3 regions. In addition, the ultrastructure of synapses in the CA1 region was examined using transmission electron microscopy (TEM). The expressions of postsynaptic densitin-95 (PSD-95) and synaptophysin (SYP) in the hippocampus were detected via western blotting. The findings revealed that compared to the CON group, the TLE group exhibited significantly prolonged escape latency, reduced platform crossing frequency, and shortened time spent in the target quadrant. The number of surviving neurons in the CA1 and CA3 regions and the expression of PSD95 and SYP protein were significantly decreased ( P  < 0.05 or P  < 0.001). However, these alterations were reversed in the TLE + HFs group. It is suggested that HFs may enhance the spatial learning and memory ability of TLE rats by preserving the integrity of hippocampal neurons, up-regulating the expression of SYP and PSD95 in hippocampus.

Cognitive impairment is a debilitating comorbidity in temporal lobe epilepsy (TLE), linked to suppressed hippocampal neurogenesis in the chronic phase. Building on evidence that links SDF-1 to epilepsy, emerging research, including our own preliminary data, suggests that its cleaved product, SDF-1(5–67), may play a critical role in this process. To investigate the therapeutic potential of SDF-1(5–67) neutralizing antibody (NAb) in a kainic acid (KA)-induced temporal lobe epilepsy (TLE) model. TLE was induced in male Wistar rats by intraventricular KA injection. Animals were divided into acute (8 days) and chronic (72 days) phase groups, including acute phase control (SHAM-A), acute phase epilepsy model (EP-A), SDF-1(5–67) NAb-treated acute phase epilepsy (S + EP-A), chronic phase control (SHAM-C), chronic phase epilepsy model (EP-C), and SDF-1(5–67) NAb-treated chronic phase epilepsy groups (S + EP-C). NAb treatment was administered via osmotic pumps. Neurogenesis (DCX + cells), neuronal loss (Nissl staining), MFS (Timm staining), cognition (Morris water maze), and SDF-1(5–67) expression (western blot) were assessed. Data were analyzed by one-way ANOVA with Tukey’s post hoc test, or repeated-measures ANOVA for water maze latency, presented as mean ± SEM. During the acute phase, increased dentate gyrus (DG) neurogenesis in EP-A vs. SHAM-A (210.43 ± 12.16 vs. 94.25 ± 7.76 cells/mm², P  < 0.05) was unaffected by NAb (195.84 ± 9.71, P  > 0.05). In the chronic phase, EP-C showed suppressed neurogenesis (51.63 ± 7.36 vs. SHAM-C 85.12 ± 5.51, P  < 0.01), which was rescued by NAb (77.56 ± 9.88, P  < 0.01). CA3 neuronal loss was attenuated by NAb in EP-C (174.33 ± 13.06 vs. EP-C 127.47 ± 10.22, P  < 0.05). MFS was increased in both phases and was unaffected by NAb. NAb improved cognitive deficits in EP-C (escape latency: 28.14 ± 1.6 s vs. EP-C 35.80 ± 2.41 s, P  < 0.05). NAb suppressed SDF-1(5–67) expression in both phases ( P  < 0.05). SDF-1(5–67) NAb promoted neurogenesis and reduced neurodegeneration in chronic TLE, and improved cognitive function without affecting MFS or seizure duration. These findings highlight its potential for postepileptic cognitive rehabilitation.

Temporal lobe epilepsy is the most common type of epilepsy in adults, is often medically refractory, and due to broad actions and long-time scales, current systemic treatments have major negative side-effects. However, temporal lobe seizures tend to arise from discrete regions before overt clinical behaviour, making temporally and spatially specific treatment theoretically possible. Here we report the arrest of spontaneous seizures using a real-time, closed-loop, response system and in vivo optogenetics in a mouse model of temporal lobe epilepsy. Either optogenetic inhibition of excitatory principal cells, or activation of a subpopulation of GABAergic cells representing <5% of hippocampal neurons, stops seizures rapidly upon light application. These results demonstrate that spontaneous temporal lobe seizures can be detected and terminated by modulating specific cell populations in a spatially restricted manner. A clinical approach built on these principles may overcome many of the side-effects of currently available treatment options. Temporal lobe epilepsy in adults does not always respond to treatment. Krook-Magnuson and colleagues use optogenetics to inhibit and activate excitatory and inhibitory neurons, respectively, in a mouse model of temporal lobe epilepsy, and find that they can stop seizures on a moment-to-moment basis.

Purpose Temporal lobe epilepsy (TLE) is a brain network disorder closely associated with synaptic loss and has a genetic basis. However, the in vivo whole-brain synaptic changes at the network-level and the underlying gene expression patterns in patients with TLE remain unclear. Methods In this study, we utilized a positron emission tomography with the synaptic vesicle glycoprotein 2 A radioligand [ 18 F]SynVesT-1 cohort and two independent transcriptome datasets to investigate the topological properties of the synaptic density similarity network (SDSN) in TLE and its correlation with significantly dysregulated risk genes. Results We observed an overall decrease in strength, reduced clustering coefficient, and increased path length of SDSN in TLE, suggesting a loss of connectivity that is accompanied by network reorganization. These changes were predominantly distributed in the temporo-limbic circuit and fronto-parietal networks. Moreover, connectivity changes in SDSN were found to be spatially correlated with the brain-wide expression of TLE risk genes, and the transcriptional correlate of SDSN changes showed a significant relationship with gene dysregulation. In particular, we identified a total of 183 downregulated genes that were functionally enriched for synaptic transmission pathways, forming a highly connected genetic interaction network. Within this set of genes, GABAergic genes such as RBFOX1 play a central role. Discussion Our study provides the first evidence that the spatial expression patterns of downregulated risk genes underlie in vivo synaptic density network dysfunction in TLE. These imaging-transcriptomic findings have the potential to guide the development of molecular and genetic network-based therapeutic approaches for TLE.

Objective To assess the long-term outcomes of patients with temporal lobe epilepsy and CSF anti-glutamate decarboxylase antibodies (GAD65-Abs). Methods We retrospectively analyzed the clinical records of 35 patients with temporal lobe epilepsy and CSF GAD65-Abs, collected from January 1993 to December 2016 and assessed cognitive impairment and seizure activity at last visit. Cognitive impairment was considered significant if impacting on daily life activities. Immunohistochemistry on rat brain slices and ELISA were used for antibody detection and titration. Results Median age was 30 years (range 2–63), 32/35 (91%) patients were female, and median follow-up was 68 months (range 7–232). At presentation, 20 patients had isolated temporal lobe epilepsy and 15 patients had other limbic symptoms, including anterograde amnesia ( n  = 10) and behavioral disturbances ( n  = 5). Progressive clinical deterioration over follow-up was reported in 28/35 patients (80%), including gradual increase of memory impairment ( n  = 25), and apparition of behavioral disturbances ( n  = 4) or mood disorders ( n  = 18). At last follow-up, 24/35 (69%) patients had cognitive disturbances with an impact on patient’s daily life activities, and 28/35 (80%) still had active seizures. Conclusion Most patients with temporal lobe epilepsy and CSF GAD65-Abs develop a chronic disease with progressive cognitive impairment and refractory epilepsy regardless of the presence of additional limbic symptoms at onset.

Ferroptosis pathway activation is potentially correlated with temporal lobe epilepsy (TLE). However, the diagnostic significance and mechanism of ferroptosis-related genes (FRGs) in TLE require further investigation. A comprehensive analysis of the GSE134697 dataset from the Gene Expression Omnibus (GEO) database using Weighted gene co-expression network analysis (WGCNA) identified 3,212 differentially expressed genes (DEGs) between temporal lobe epilepsy (TLE) and control groups, with a critical focus on the turquoise module. Through intersection of DEGs and key module genes, correlation analyses with functional-related genes (FRG), protein-protein interactions (PPI), least absolute shrinkage and selection operator (LASSO), and machine learning methods, five potential biomarkers of ferroptosis ( CBS , SHMT1 , RIN3 , QDPR , and PLPP4 ) were isolated. A nomogram was constructed using these markers, and enrichment analyses revealed their links to T-cell activation, allograft rejection, and glial differentiation. Variations in 13 immune cell types were also noted. Upregulation of CBS , RIN3 , QDPR , and PLPP4 in TLE was confirmed through RT-qPCR and Western blot assays. Additionally, five SHMT1 -targeting and one CBS -targeting drugs were predicted using the Drug-Gene Interaction Database (DGIdb). These findings provide new insights into the potential pathogenesis of TLE and suggest new targets for future research.