Rich2 inhibits the NLRP3 inflammasome in epilepsy formation by regulating autophagy

Abstract

Abstract Background The intricate pathophysiology of epilepsy has hindered the advancement of efficacious therapies. Despite the existence of a dozen antiseizure drugs (ASDs) with favorable effects on seizure management globally, approximately 30% of patients continue to exhibit resistance to ASDs. Neuroinflammation seems to play a pivotal role in the disease's progression. Rich2 (Rho GTP enzyme-activated protein 44) is a protein-coding gene, the functions of which include participation in the RAC1 GTP enzyme cycle and the RHOC GTP enzyme cycle. Recent studies have found that the dysfunction of Rac 1-autophagy-related pathways not only hinders the clearance of pathogens or nonorganicparticles but also participates in the dysfunction of T cells and macrophages and that the activation of Rac 1 or mTOR can reverse ibandronate (IBAN)-induced autophagy. It has been shown that autophagy can regulate the activation of the NLRP3 inflammasome, which is significantly enhanced after the inhibition of autophagy. However, the role of Rich2 in epilepsy remains unclear. This study aimed to investigate the mechanism of Rich2 in epilepsy. Methods Adult male C57BL/6 mice were intracranially administered kainic acid (KA) to establish an epilepsy model and were pretransfected with adeno-associated virus (AAV) three weeks prior to KA injection. Additionally, SH-SY5Y cells were transfected with AAV for 48 hours and subsequently treated with KA for 6 hours. Immunoblot analysis, immunofluorescence staining, seizure video monitoring, LFP (local field potential) recording, and Nissl staining were performed individually. VX 765 was orally administered 30 minutes prior to KA induction (at 10 am and 4 pm) for a duration of 7 days until the mice were euthanized. Results In the KA-induced temporal lobe epilepsy (TLE) model, Rich2 expression was reduced in the hippocampus, and it was lowest at 3 days after KA injection. Overexpression of Rich2 significantly attenuated epileptic activity, reduced neuronal damage after status epilepticus (SE), and downregulated IL-1β, IL-18 and pyrin domain protein 3 (NLRP3) inflammasome expression through activation of autophagy, while downregulation of Rich2 hadthe opposite effects. Inhibition of cysteine-aspartic-specific proteinase-1 (caspasase-1) by VX765 reversed the effect of Rich2 knockdown. Conclusion Rich2 influences seizure activity and impacts neuronal viability in a mouse model of temporal lobe epilepsy induced by KA. Additionally, Rich2 governs neuroinflammation in epileptic subjects through the regulation of NLRP3/Caspase-1/IL-1β signaling via autophagy activation.