Abstracts

Rationale: Mesial temporal lobe epilepsy(MTLE) is one of the most common drug-refractory epilepsy with high prevalence. Mitochondrial dysfunction is currently considered to be a key factor in the development of MTLE. The role of mitochondrial factors in MTLE is unclear and there is no systematic, coherent study. In our previous studies, it has been found that the pathogenesis of MTLE is related to trigger factors such as early brain injury. There are so many patients with early brain injury, while MTLE patients with chronic spontaneous attack in the later stage are still a relatively small part. Obviously, the acquired factors such as inflammation activation and mitochondrial dysfunction are insufficient. Whether there are genetic susceptible factors for different individuals, whether there is a mutation in mitochondrial genetic material after a series of stimulations such as SE, there is still no relevant research. Therefore, we investigated mitochondrial dysfunction and its susceptible/mutated genes in MTLE. Methods: This study used MTLE animal model and epilepsy cell model to determine mitochondrial function changes and the changes of mitochondrial genetic material in hippocampus from six aspects: mitochondrial morphology, ATP production rate, respiratory chain enzyme complex I activity, mitochondrial membrane potential, calcium homeostasis and mtDNA copy number variation. At the same time, the second-generation sequencing technology was used to detect genetic susceptibility genes and mitochondrial genetic material in postoperative hippocampus and peripheral blood of MTLE patients. Results: In the MTLE animal model, compared with the control group, the mitochondrial morphology showed mitochondrial swelling, ridge rupture and vacuolization in the acute period, slightly swollen and the arrangement of ridge was disordered in chronic period, but there was no significant change in latent period. The ATP production rate was significantly reduced in the acute, latent and chronic period. The activity of the respiratory chain enzyme complex I decreased in the acute and chronic period, and there was no significant difference in the latent period. MtDNA copy number decreased in the acute period, there was no significant difference in the latent period, and the chronic period increased. In the epileptic cell model, compared with the control cells, the cell membrane potential decreased, and the intracellular calcium ion concentration increased. In addition, the whole exon sequencing of hippocampus in 20 patients with MTLE was performed. The positive results were 9 cases. The genetic susceptibility genes were RELN, JRK, CACNA1H, CACNA1A, TICAM1, GCH1, DGKD, and SIK1. The full length of mtDNA genome was sequenced in hippocampal tissue of 20 patients and peripheral blood of 7 patients with MTLE. 5 of 20 patients showed that there were class I pathogenic mutations in hippocampus tissue, and the mutations all were located in the transcript NC.012920. The full length of mtDNA sequencing results of peripheral blood in 7 patients were negative. Conclusions: In this study, we successfully confirmed that mitochondrial dysfunction was involved in the pathogenesis of MTLE both in vivo and in vitro. At the same time, we also confirmed that early brain injury can lead to changes in mitochondrial genetic material in hippocampus tissue in the animal model of MTLE. In addition, from the genetic level, it was first confirmed that genetic susceptibility factors and post-epileptic mitochondrial gene mutations are involved in the regulation of chronic epileptic formation in MTLE. The positive changes of mitochondrial genetic material in hippocampus tissue and negative results in peripheral blood in patients with MTLE also indicated that there was somatic genetic mutations in MTLE. This study opens up a new perspective for the study of clinically refractory MTLE, and provides a theoretical basis for avoiding triggering gene mutations and seeking new targets for the development of antiepileptic drugs. Funding: The National Natural Science Fund.