Agmatine Alleviates Epileptic Seizures and Hippocampal Neuronal Damage by Inhibiting Gasdermin D-Mediated Pyroptosis

Abstract

Background: Epilepsy is a common neurological disease, and neuroinflammation is one of the main contributors to epileptogenesis. Pyroptosis is a type of pro-inflammatory cell death that is related to epilepsy. Agmatine, has anti-inflammatory properties and exerts neuroprotective effects against seizures. Our study investigated the effect of agmatine on the core pyroptosis protein GSDMD in the context of epilepsy.Methods: A chronic epilepsy model and BV2 microglial cellular inflammation model were established by pentylenetetrazole (PTZ)-induced kindling or lipopolysaccharide (LPS) stimulation. H&E and Nissl staining were used to evaluate hippocampal neuronal damage. The expression of pyroptosis and inflammasome factors was examined by western blotting, quantitative real-time PCR, immunofluorescence and enzyme-linked immunosorbent assay (ELISA).Results: Agmatine disrupted the kindling acquisition process, which decreased seizure scores and the incidence of full kindling and blocked hippocampal neuronal damage. In addition, agmatine increased BV2 microglial cell survival in vitro and alleviated seizures in vivo by suppressing the levels of PTZ-induced pyroptosis. Finally, the expression of TLR4, MYD88, phospho-IκBα, phospho-NF-κB and the NLRP3 inflammasome was significantly upregulated in LPS-induced BV2 microglial cells, while agmatine suppressed the expression of these proteins.Conclusions: Our results indicate that agmatine affects epileptogenesis and exerts neuroprotective effects by inhibiting neuroinflammation, GSDMD activation, and pyroptosis. The inhibitory effect of agmatine on pyroptosis was mediated by the suppression of the TLR4/MYD88/NF-κB/NLRP3 inflammasome pathway. Therefore, agmatine may be a potential treatment option for epilepsy.

Agmatine Mitigates Inflammation-Related Oxidative Stress in BV-2 Cells by Inducing a Pre-Adaptive Response

“…Although we have not measured the intracellular H 2 O 2 , we expect that oxidative burst alongside three times lesser CAT activity in Lps-stimulated cells than homeostatic cells might create an H 2 O 2 permissive environment, promoting its role as a mediator/amplifier of microglial activation. In this study, agmatine prevents Lps-induced NF-κB translocation to the nucleus due to the inhibition of IκB degradation, which agrees with previous reports [ 60 , 69 , 70 ]. In addition, the ability of agmatine to decrease iNOS activity and NO production in Lps-activated cells is probably the cause of CAT deinhibition, thus limiting H 2 O 2 role as a signaling molecule in NF-kB activation.…”

Research Progress of Pyroptosis in Alzheimer’s Disease

“…After injection of AAV9-siRNA-caspase-1, the behavior of AD mice in cognitive function experiments was alleviated, and the expressions of NLRP3, caspase-1, and GSDMD were down regulated in both cerebral cortex and hippocampus ( Han et al, 2020 ). It has been reported that guanidine reduced hippocampal neuron damage by inhibiting GSDMD-mediated pyroptosis ( Li et al, 2021 ). These studies suggested that both GSDMs and pyroptosis -related proteins were expressed in the hippocampus, and inhibition of pyroptosis-related proteins could reduce hippocampus damage and play a positive role in the treatment of AD.…”

Distinct Cell-specific Roles of NOX2 and MyD88 in Epileptogenesis

“…Besides that, microglia disrupts gammaaminobutyric acid (GABA) signaling and regulates the neural expression of NR1 and NR2b subunits of NMDA receptor. These processes result in high excitability of neurons which, in turn, contributes to epileptogenesis (Vezzani et al, 2013;Liu et al, 2018;Xueying Li et al, 2021).…”

“…In neuroinflammation, astroglial activation through the MyD88 pathway creates a harmful environment to the neural tissue, characterized by an astrocytic hypertrophic state, which impairs the blood-brain barrier and neural communication maintenance. (Vezzani et al, 2013;Liu et al, 2018;Xueying Li et al, 2021). Astrocytic activation can occur by MyD88-dependent TLR4 via the extracellular signal-related kinase (ERK) pathway, and promotes excitatory synapse development, resulting in increased seizure susceptibility (Henneberger and Steinhauser, 2016;Shen et al, 2016).…”