RelB mediated by GSK3β/IκBα as a potential therapeutic target in pilocarpine seizure model rats and drug-resistant epilepsy patients

Background

Drug-resistant epilepsy (DRE) affects more than 20 million people worldwide. DRE patients do not respond to anti-seizure medications. Shifting from anti-seizure to anti-epileptic and disease-modifying therapy will be an important aim for future research. The canonical nuclear factor kappa B (NF-κB) signaling pathway plays a pivotal role in epilepsy and neuroinflammation. However, the expression and regulation of RelB, which can be activated via both canonical and non-canonical NF-κB signaling, are obscure in epilepsy. To clarify the expression and localization of RelB in the DRE phenotype and to determine the proteins related to RelB regulation, we conducted the following studies.

Methods

Quantitative PCR was performed to detect the transcription of RELB in pilocarpine-induced epileptic rats. Western blotting was used to determine the abundance of RelB and proteins related to RelB regulation in brain tissue from both epilepsy model rats and DRE patients and in liposaccharide-induced HT22 cells. Immunofluorescence staining and immunohistochemistry were used to locate RelB in brain sections from DRE patients. ELISA was used to determine inflammatory cytokines secreted by HT22 cells into the culture medium.

Results

RELB transcription and expression were increased in the hippocampus and cortex of epileptic rats during the acute and latent phases and in epileptic foci of patients with temporal lobe epilepsy. Additionally, RelB levels were mainly increased in epileptic rat neurons and accumulated in the nuclei of hippocampal neurons. Further research demonstrated increased GSK3β phosphorylation at the Ser9 inhibitory site and decreased IκBα levels, which contributed to RelB accumulation in hippocampal neurons after seizure and in liposaccharide-stimulated HT22 cells.

Conclusions

This study is the first to demonstrate that RelB is widely distributed and increased in epileptogenic foci neurons in epileptic phenotypes. These results indicate that RelB may play roles in DRE and is mediated by GSK3β and IκBα, providing a new target for anti-epileptic and disease-modifying therapy.