Trimethylamine N-Oxide Aggravates Neuro-inflammation in Spinal Cord Injury Through NLRP3 Inflammasome Activation in Microglia.

Trimethylamine oxide (TMAO), a gut microbiota metabolite, has been shown to be associated with neurological diseases, but its role in spinal cord injury (SCI) remains unclear. This study investigated the contribution of TMAO in the pathogenesis of SCI. A combination of in vivo and in vitro approaches was employed to investigate the role of TMAO in SCI. Mouse models of SCI were established to evaluate neurological function, histopathology, and inflammasome activation following TMAO treatment or inhibition. BV2 microglial cells were subjected to oxygen-glucose deprivation (OGD) to examine the impact of TMAO on neuro-inflammation and NLRP3 activation. Molecular and biochemical techniques, including western blot, immunofluorescence, and ELISA, were used to assess inflammasome signaling and inflammatory responses. The therapeutic potential of TMAO inhibition (DMB) and NLRP3 blockade (MCC950) was systematically evaluated in both animal and cellular models, along with the verification in vitro using gene knockdown. TMAO exacerbated SCI in mice, worsening weight loss, neurological deficits, and neuronal damage while increasing microglial NLRP3 inflammasome activation, inflammatory cytokine release, and immune cell infiltration. Both DMB and MCC950 attenuated these effects, restoring tissue integrity and functional recovery. In microglia, TMAO amplified NLRP3-driven neuro-inflammation under OGD condition, an effect reversed by MCC950. Notably, DMB similarly suppressed TMAO-mediated microglial activation. NLRP3 knockdown reversed the impact of TMAO on pyroptosis. Our findings demonstrate that TMAO exacerbates spinal cord injury and activates the NLRP3 inflammasome in microglia, amplifying neuro-inflammation. Inhibition of TMAO or NLRP3 attenuates these pathological effects, suggesting that targeting the TMAO-NLRP3 axis represents a promising therapeutic strategy for SCI.