Negative Regulation of Autophagy in Activating Nucleotide-Binding Oligomerization Domain-Like Receptor Family Pyrin Domain-Containing 3 Inflammasomes in the Hippocampus of an Epilepsy Rat Model

Epilepsy, characterized by unpredictable and periodic seizures, is associated with chronic hippocampal inflammation and autophagy. Moreover, a molecular relationship between autophagy and inflammation in neurodegenerative disorders has been reported, highlighting the role of autophagy in the regulation of inflammation. To the best of our knowledge, there is no previous evidence of an association between nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome and autophagy in epilepsy. Hence, we in this study aimed at investigating the possible association between NLRP3 inflammasome activation and autophagy in the development of epilepsy. A rat model of temporal lobe epilepsy was induced with lithium-pilocarpine. Five groups, i.e., control (n = 20), status epilepticus (SE, n = 30), SE + control (siRNA; n = 15), SE + NLRP3 siRNA (n = 30), and SE + wortmannin (n = 30), were investigated. Real-time quantitative reverse transcription polymerase chain reaction, Western blotting, and quantum dot-based immunohistochemistry were used to detect the mRNA/protein expression levels of NLRP3, caspase-1, interleukin (IL)-1 beta, IL-18, Beclin-1, and microtubule-associated protein light chain 3 (LC3 beta) in the hippocampus. In addition, transmission electron microscopy was utilized to investigate autophagosome in the hippocampus of SE rats. We found that mRNA and protein expressions of NLRP3, caspase-1, IL-1 beta, IL-18, LC3 beta, and Beclin-1 were activated in the hippocampus. Gene silencing of NLRP3 suppressed caspase-1, IL-1 beta, and IL-18 release and significantly ameliorated hippocampal damage. Furthermore, the LC3 beta and Beclin-1 expression levels decreased significantly after treatment with wortmannin. Importantly, NLRP3 inflammasome activation and IL-1 beta/IL-18 releases were significantly enhanced after treatment with wortmannin, which implied a negative association between autophagy inhibition and NLRP3 inflammasome activation. Our study provides the first evidence that autophagy plays an important role in NLRP3 inflammasome activation in the development of epilepsy. These findings suggest that regulation of autophagy may be a promising potential strategy for treating patients with epilepsy.