Inhibition of Gasdermin D-Mediated Pyroptosis Attenuates the Severity of Seizures and Astroglial Damage in Kainic Acid-Induced Epileptic Mice.

Lu Xia,Yiying Cai,Lu Liu,Xin Wang,Fangchao Tong,Qiang Wang,Jing Ding,Yiying Zhang

doi:10.3389/fphar.2021.751644

Abstract

Objective: Our study aimed to explore whether gasdermin D (GSDMD)-mediated pyroptosis is involved in the mechanism of kainic acid-induced seizures. Methods: C57BL/6 mice were randomly divided into sham and epilepsy groups. The epilepsy group was intrahippocampally injected with kainic acid to induce status epilepticus (SE), and the sham group was injected with an equal volume of saline. Dimethyl fumarate (DMF) was used as the GSDMD N-terminal fragments (GSDMD-N) inhibitor and suspended in 0.5% sodium carboxymethyl cellulose (CMC) for orally administration. The epilepsy group was divided into SE + CMC and SE + DMF groups. In the SE + DMF group, DMF was orally administered for 1 week before SE induction and was continued until the end of the experiment. An equal volume of CMC was administered to the sham and SE + CMC groups. Recurrent spontaneous seizures (SRSs) were monitored for 21 days after SE. Western blot analysis and immunofluorescent staining was performed. Results: The expression of GSDMD increased at 7–21 days post-SE, and GSDMD-N expression was significantly elevated 7 days after SE in both ipsilateral and contralateral hippocampus. GSDMD-positive cells were co-labeled with astrocytes, but not neurons or microglia. Astroglial damage occurs following status epilepticus (SE). Damaged astrocytes showed typical clasmatodendrosis in the CA1 region containing strong GSDMD expression at 7–21 days post-SE, accompanied by activated microglia. In the SE + DMF group, the expression of GSDMD-N was significantly inhibited compared to that in the SE + CMC group. After administration of DMF, SRSs at 7–21 days after SE were significantly decreased, and the number of clasmatodendritic astrocytes, microglia, and the expression of inflammatory factors such as IL-1β and IL-18 were significantly attenuated. Conclusion: GSDMD-mediated pyroptosis is involved in the mechanism of kainic acid-induced seizures. Our study provides a new potential therapeutic target for seizure control.

Highlights

Epilepsy is a common neurological disease that affects over 70 million people worldwide, with an annual incidence of approximately 50–100 per 100,000 persons (Thijs et al, 2019)
Our study aimed to explore whether gasdermin D (GSDMD)-mediated pyroptosis is involved in the mechanism of kainic acid-induced seizures
The aim of the present study was to explore whether GSDMDmediated pyroptosis is involved in the mechanism of kainic acidinduced seizures and whether inhibiting GSDMD N-terminal fragments (GSDMD-N) can attenuate pyroptosis and the severity of seizures

Summary

Introduction

Epilepsy is a common neurological disease that affects over 70 million people worldwide, with an annual incidence of approximately 50–100 per 100,000 persons (Thijs et al, 2019). Accumulating evidence indicates that neuroinflammation plays an important role in the severity of epilepsy (Aronica et al, 2017). Activated caspase-1 cleaves gasdermin D (GSDMD) to release the N-terminal fragment (GSDMD-N), which forms pores in the cell membrane, leading to the release of inflammatory factors and damage-associated molecular patterns (DAMPs), such as high-mobility group box 1 (HMGB1) and adenosine 5′-triphosphate (ATP), resulting in cell death (Kayagaki et al, 2015; Shi et al, 2015). In the non-canonical pathway, GSDMD is cleaved by caspases-4/5/11 to induce pyroptosis (Huang et al, 2019). GSDMD cleavage serves as an important checkpoint in pyroptosis in both canonical and non-canonical pathways and plays an important role in central nervous system diseases such as Alzheimer’s disease, cerebral ischemia, and multiple sclerosis (McKenzie et al, 2018; Han et al, 2020; Li et al, 2020)

Methods

Results

Conclusion