Attenuates reactive oxygen species: induced pyroptosis via activation of the Nrf2/HO-1 signal pathway in models of trigeminal neuralgia

Abstract

In this study, we examined the impact of demyelinating and neuroinflammation on trigeminal neuralgia (TN) by utilizing models of chronic constriction injury to the infraorbital nerve (CCI). The CCI rats were treated with either VX-765 (an inhibitor of caspase-1) or a control solution of PBS/DMSO to observe the effects on neurobehavioral and neuropathological outcomes. The histochemical changes, pyroptosis-related proteins were assessed using immunohistochemistry, Elisa, and western blotting. RSC96 cells were pretreated with belnacasan (VX-765, an inhibitor of caspase-1), Gasdermin D(GSDMD)-targeting siRNAs, cobalt protoporphyrin (CoPP) or zinc protoporphyrin (Znpp) before being exposed to H₂O₂. Following these treatments, the Reactive oxygen species (ROS) level, cell viability, percentage of pyroptosis, pyroptosis-related proteins, nuclear factor erythroid 2-related factor 2 (Nrf2) and HO-1 level was measured. The scanning electron microscopy revealed increased ball-like bulge and membrane pore formation in the CCI group. In the CCI and CCI+ Vehicle groups, we found ROS level and expression of pyroptosis-related proteins increased. While, treatment with VX-765resulted in a decreased expression of GSDMD, IL-1, IL-18, and caspase-1 decreased. In the in-vitro study, RSC96 cells showed mild pyroptosis and overall mild edema after being exposed to H₂O₂. The ROS level, percentage of pyroptosis, pyroptosis-related proteins, Nrf2 and HO-1 level increased significantly in the H₂O₂ group. While, the percentage of pyroptosis and pyroptosis-related proteins decreased significantly in the H₂O₂ + VX-765 group, H₂O₂ + siRNA group, and H₂O₂ + VX-765 + siRNA group. After treatment with HO-1-inhibitor Znpp and HO-1-activator Copp, the percentage of pyroptosis and pyroptosis-related proteins increased and decreased significantly respectively. In conclusions, the pyroptosis of Schwann cell in the CCI model generated the demyelination of TN nerve. The ROS is an upstream event of NLRP3 inflammasome activation which induced eventual pyroptosis. The Nrf2/HO-1 signaling pathway could protect the H₂O₂-induced pyroptosis in RSC96 cells.