Role of Stat3 in NLRP3/caspase-1-mediated hippocampal neuronal pyroptosis in epileptic mice

Abstract

Epilepsy, a fairly common neurological disorder, is linked to various sequelae and greatly impairs the quality of life. Meanwhile, there is evidence to suggest an association between pyroptosis and epilepsy. Accordingly, the current study sought to determine the role of signal transduction activator of transcription 3 (Stat3) in pyroptosis in epileptic mice. First, epileptic mouse models were induced by lithium chloride, atropine, and pilocarpine, and HT22 cells were treated with lipopolysaccharide (LPS) to establish in vitro hippocampal neuronal inflammation models. Subsequently, Stat3, NOD-like receptor protein 3 (NLRP3), cleaved-caspase-1, gasdermin D (GSDMD)-N, activated Stat3 (p-Stat3), and H3K9Ac levels were detected in the mouse hippocampus and HT22 cells. Morris water maze test was further performed to detect changes in the learning and memory abilities of epileptic mice, and hematoxylin-eosin staining and Nissl staining were conducted to detect the pathological injury. HT22 cell proliferation and apoptosis were also detected using a cell counting kit-8 assay and flow cytometry. An enzyme-linked immunosorbent assay was adopted to detect Interleukin (IL)-1β and IL-18 concentrations in the mouse hippocampus and HT22 cells. Furthermore, the enrichment of H3K9Ac and p-Stat3 in the NLRP3 promoter region was detected with the help of a chromatin immunoprecipitation assay. The obtained findings revealed that Stat3 was highly expressed in the hippocampus of epileptic mice and LPS-treated HT22 cells. Meanwhile, Stat3 silencing brought about improvements in the learning and memory abilities of the mice, in addition to alleviation of hippocampal neuronal damage and pyroptosis-related factors in hippocampal tissue and HT22 cells. We also observed that Stat3 bound to the NLRP3 promoter to promote H3K9 acetylation and NLRP3 transcription. Moreover, increasing H3K9Ac in cells annulled the inhibition of silencing Stat3 on neuronal pyroptosis. To conclude, our findings revealed that Stat3 bound to the NLRP3 promoter to augment H3K9 acetylation, NLRP3 transcription, and NLRP3/caspase-1-mediated neuronal pyroptosis, resulting in aggravation of neuronal damage in epileptic mice.

Keywords: NLRP3; Stat3; epilepsy; neuronal injury.