Interleukin-1β and microRNA-146a in an immature rat model and children with mesial temporal lobe epilepsy

Purpose: Increasing evidence indicates that neuroinflammation plays a critical role in the pathogenesis of mesial temporal lobe epilepsy (MTLE). The aim of this study was to investigate the dynamic expression of interleukin (IL)1 beta as a proinflammatory cytokine and microRNA (miR)-146a as a posttranscriptional inflammation-associated microRNA (miRNA) in the hippocampi of an immature rat model and children with MTLE. Methods: To study the expression of IL-1 beta and miR-146a, we performed a reverse transcription polymerase chain reaction, Western blot, and real-time quantitative PCR on the hippocampi of immature rats at 11 days of age. Expression was monitored in the acute, latent, and chronic stages of disease (2 h and 3 and 8 weeks after induction of lithium-pilocarpine status epilepticus, respectively), and in control hippocampal tissues corresponding to the same timeframes. Similar expression methods were applied to hippocampi obtained from children with MTLE and normal controls. Key Findings: The expression of IL-1 beta and miR-146a in both children and immature rats with MTLE differs according to the stage of MTLE development. Both IL-1 beta and miR-146a are significantly up-regulated, but in opposite ways: IL-1 beta expression is highest in the acute stage, when expression of miR-146a is at its lowest level; miR-146a expression is highest in the latent stage, when IL-1 beta expression is at its lowest level. Both IL-1 beta and miR-146a are up-regulated in the chronic stage, but not as much as in the other stages. Significance: Our study is the first to focus on the expression of miR-146a in the immature rat model of lithium-pilocarpine MTLE and in children with MTLE. We have detected that the expression of proinflammatory cytokine IL-1 beta and posttranscriptional inflammation-associated miR-146a is variable depending on the disease stage. Furthermore, both IL-1 beta and miR-146a are up-regulated in immature rats and children with MTLE. Our findings elucidate the role of inflammation in the pathogenesis of MTLE in the immature rat model and children. Therefore, modulation of the IL-1 beta miR-146a axis may be a novel therapeutic target in the treatment of MTLE.