Tripchlorolide Inhibits Microglial Activation by Modulating STING-NLRP3 Signaling Pathway in Pilocarpine-Induced Status Epilepticus Model

Abstract

Background: Microglia activation, a defining feature of brain inflammation, plays a crucial role in the pathogenesis of epilepsy. Tripchlorolide (T4) is capable of inhibiting inflammatory threats to the central nervous system (CNS). However, relevant mechanisms of action for T4 in epilepsy treatment have not been well reported. We aimed to evaluate the effect of Tripchlorolide (T4) on microglial activation and stimulator of interferon genes—nucleotide-binding oligomerization domain-like receptor pyrin domain containing 3 (STING-NLRP3) signaling pathway in epilepsy by the uses of both in vivo and in vitro experiments. Methods: Forty mice were divided into four groups: Blank control, status epilepticus (SE), SE+vehicle, and SE+T4. Following establishment of pilocarpine-induced SE mouse model, T4 was administered to mice in SE+T4 group, while saline or dimethyl sulfoxide to other groups. The induction frequency was once every three days for total of 60 days. The treatment outcomes were assessed after each experiment. Inflammatory cytokines were measured by Enzyme linked immunosorbent assay (ELISA) to analyze the microglial activation and effect of T4. The effect of T4 on STING-NLRP3 signaling pathway was evaluated in vivo by western blotting (WB). With cell lines, the alterations of STING-NLRP3 signaling pathway were assayed in vitro by WB. Results: The latency to SE and mortality were improved after T4 treatment (p < 0.001). T4 markedly reduced levels of the inflammatory factors following their significant rise after SE induction (all p < 0.01). Application of pilocarpine increased the expressions of relevant proteins associated with inflammation and STING-NLRP3 signaling pathway and apoptosis in mouse brain tissue, whereas T4 treatment altered these abnormal upregulations (p < 0.001). The abundance of STING and NLRP3 in cells and endoplasmic reticulum (ER) was up-regulated in the SE groups but inhibited by T4 treatment (all p < 0.05). Conclusions: T4 may inhibit the activation of microglia and improve SE by regulating the STING-NLRP3 pathway. This discovery provides new insight for the treatment of epilepsy.