Abnormal Rat Cortical Development Induced by Ventricular Injection of rHMGB1 Mimics the Pathophysiology of Human Cortical Dysplasia.

Cortical dysplasia (CD) is a common cause of drug-resistant epilepsy. Increasing studies have implicated innate immunity in CD with epilepsy. However, it is unclear whether innate immune factors induce epileptogenic CD. Here, we injected recombinant human high mobility group box 1 (rHMGB1) into embryonic rat ventricles to determine whether rHMGB1 can induce epileptogenic CD with pathophysiological characteristics similar to those of human CD. Compared with controls and 0.1 µg rHMGB1-treated rats, the cortical organization was severely disrupted in the 0.2 µg rHMGB1-treated rats, and microgyria and heterotopia also emerged; additionally, disoriented and deformed neurons were observed in the cortical lesions and heterotopias. Subcortical heterotopia appeared in the white matter and the gray-white junction of the 0.2 µg rHMGB1-treated rats. Moreover, there was decreased number of neurons in layer V-VI and an increased number of astrocytes in layer I and V of the cortical lesions. And the HMGB1 antagonist dexmedetomidine alleviated the changes induced by rHMGB1. Further, we found that TLR4 and NF-κB were increased after rHMGB1 administration. In addition, the excitatory receptors, N-methyl-D-aspartate receptor 1 (NR1), 2A (NR2A), and 2B (NR2B) immunoreactivity were increased, and immunoreactivity of excitatory amino acid transporter 1 (EAAT1) and 2 (EAAT2) were reduced in 0.2 µg rHMGB1-treated rats compared with controls. While there were no differences in the glutamic acid decarboxylase 65/67 (GAD65/67) immunoreactivity between the two groups. These results indicate that the excitation of cortical lesions was significantly increased. Furthermore, electroencephalogram (EEG) showed a shorter latency of seizure onset and a higher incidence of status epilepticus in the 0.2 µg rHMGB1-treated rats; the frequency and amplitude of EEG were higher in the treated rats than controls. Intriguingly, spontaneous electrographic seizure discharges were detected in the 0.2 µg rHMGB1-treated rats after 5 months of age, and spike-wave discharges of approximately 8 Hz were the most significantly increased synchronous propagated waves throughout the general brain cortex. Taken together, these findings indicate that rHMGB1 exposure during pregnancy could contribute to the development of epileptogenic CD, which mimicked some pathophysiological characteristics of human CD.

TRIF contributes to epileptogenesis in temporal lobe epilepsy during TLR4 activation.

Increasing evidence indicates that inflammatory processes play a crucial role in the etiopathology of epilepsy and seizure disorders. The Toll/IL-1R domain-containing adapter-inducing IFN-ß (TRIF) activated several transcriptions leading to the production of pro-inflammatory cytokines in the central nervous system, which suggests a potential role for TRIF in the epileptogenesis of epilepsy. In this study, we investigated the roles of TRIF in human and mice epileptogenic tissues. Western blot and immunohistochemistry assays showed that the expression of TRIF was significantly upregulated in neurons and glial cells in both human epileptic tissues and mouse models, and positively correlated with seizure frequency. TRIF expression positively correlated with high-mobility group box 1 (HMGB1) expression. In TRIF-deficient mice, electroencephalograms displayed a significant decrease in seizure frequency and duration time, while KA induced seizures compared with wild-type (WT) mice. The number and duration time of spontaneous seizures were also decreased in the chronic KA-induced TRIF-deficient mouse models. In TLR4-deficient hippocampal neurons and mouse models, TRIF expression was lower compared with WT mice during HMGB1 and KA stimulation. Meanwhile, in KA-induced TRIF-deficient mouse models, microglia activation was significantly suppressed; pro-inflammatory factors including IL-1ß, TNF-α, iNOS, HMGB1 and IFN-ß were reduced; and the survival of the neurons in the hippocampus increased compared with WT mice. Our findings suggested that TRIF may be involved in the epileptogenesis of temporal lobe epilepsy, which would make it a potential therapeutic target for the treatment of epilepsy.

A Retrospective Analysis of Stereoelectroencephalography and Subdural Electroencephalography for Preoperative Evaluation of Intractable Epilepsy.

BACKGROUND: Different methods for intracranial electrode recording have various advantages and disadvantages, and controversy exists regarding the complications of stereoelectroencephalography (SEEG) and subdural EEG. OBJECTIVE: The purpose of this study was to determine the efficacy and safety of SEEG by comparing it with subdural EEG. METHODS: Data from 100 patients who underwent SEEG (n = 48) and subdural EEG (n = 52) to evaluate the epileptogenic zone were collected from June 2011 to June 2015. The evaluation results, surgical outcomes, and complications were compared. RESULTS: No significant differences were noted between the SEEG and subdural EEG groups in identifying the epileptogenic zone or undergoing epileptic surgery. Of the 88 patients who underwent epilepsy surgery after assessment, 59.5% in the SEEG group and 52.2% in the subdural EEG group became seizure free. No significant differences in postoperative seizure control or intelligence improvement were noted. The overall complication rate in SEEG patients (8/48; 16.7%) was lower than that in subdural EEG patients (13/52; 25%), particularly for hemorrhage and infection (4.2 vs. 17.3%, p < 0.05). CONCLUSIONS: This retrospective review indicates that SEEG has low associated complications, particularly regarding hemorrhage and infection. SEEG is a safe and effective method for intracranial monitoring.