Thiolutin attenuates neuroinflammation and neuronal apoptosis by suppressing microglial pyroptosis through NLRP3 inflammasome inhibition after spinal cord injury.

Traumatic spinal cord injury (SCI) initiates a neuroinflammatory response dominated by tissue-resident microglia. Thiolutin (THL) can weaken several inflammatory diseases by blocking the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation. At present, whether THL improves functional recovery after SCI is unclear. Crosstalk between neurons and microglia was simulated by a co-culture system in which microglia were activated by LPS + ATP and treated with THL. Contused SCI mouse models were constructed for studying the efficacy of THL and related mechanisms. Motor function of mice was assessed by BMS scoring, incline plane test, and footprint analysis. Pathological alterations following SCI were determined by hematoxylin-eosin, luxol fast blue, and Nissl staining. Neuronal apoptosis in vitro was assessed by flow cytometry and Tunel staining. The NLRP3 inflammasome activation, inflammatory response, and microglia polarization were assessed by western blot, ELISA, and immunofluorescence. THL treatment repressed microglia pyroptosis-induced neuronal apoptosis and inflammatory response in a co-culture system in vitro. Also, treatment with THL repressed microglial activation and M1-type polarization, along with the NLRP3 inflammasome activation. Furthermore, THL treatment improves motor function of mice with SCI, accompanied by reduced cavity area of the spinal cord, inflammatory response, M1-type microglia polarization, and enhanced remyelination and neuronal regeneration. However, THL treatment did not work in SCI-experienced Nlrp3-/- mice. THL improves motor function following SCI by repressing neuroinflammation and neuronal apoptosis via suppressing NLRP3 inflammasome-mediated microglial polarization and pyroptosis.