From Molecular Docking to Rat Models: Butyrate From a High-Fiber Diet Inhibits HDAC1 and NLRP3 Inflammasome to Alleviate Oxidative Stress and Inflammation After Spinal Cord Injury

Spinal cord injury (SCI) induces complex inflammatory and oxidative stress responses that exacerbate secondary damage and impair functional recovery. This study investigated the role of butyrate—a microbiota-derived short-chain fatty acid (SCFA)—in ameliorating SCI using a combination of in silico, in vitro, and in vivo approaches. We first performed gut microbiota 16S rRNA sequencing and targeted metabolomics to assess microbial dysbiosis and serum SCFA levels in rats post-SCI. A marked reduction in butyrate-producing Firmicutes and serum butyrate concentrations was observed after injury. Molecular docking predicted a direct interaction between butyrate and HDAC1, which was confirmed by a ~40% reduction in HDAC1 expression in spinal cord tissue, as demonstrated by Western blot and immunofluorescence. In microglial cultures, butyrate significantly inhibited LPS + ATP-induced NLRP3 inflammasome activation by approximately 38%. For the in vivo component, a cervical hemi-contusion SCI model at the C5 level was established in rats. To restore butyrate levels, animals were either fed a high-fiber diet (HFD) or received intrathecal butyrate administration. Behavioral assessment revealed a 1.5-fold improvement in Forelimb Locomotor Scale scores at 1 month post-injury, and motor-evoked potential recordings showed nearly a 1.8-fold enhancement, indicating significantly improved locomotor and electrophysiological recovery in HFD-treated rats compared to controls. Furthermore, HFD treatment resulted in reduced oxidative stress (as evidenced by lower MDA and DHE staining), decreased inflammation, while butyrate administration promoted M2-type macrophage/microglia polarization. These findings reveal that butyrate mitigates oxidative stress and inflammation by targeting HDAC1 and the NLRP3 inflammasome. Importantly, HFD-driven restoration of microbial butyrate production represents a promising and translationally relevant non-invasive therapeutic strategy to enhance SCI recovery via the gut-spinal cord axis.