Lactylation-driven YTHDF3 promotes microglial pyroptosis in sepsis-associated encephalopathy via the Usp9x/NLRP3 Axis.

BACKGROUND: YTHDF3 expression is up-regulated in sepsis-associated encephalopathy (SAE), yet its precise function remains to be fully elucidated. This study aims to investigate the role of YTHDF3 in microglial pyroptosis during SAE and to explore its upstream and downstream regulatory mechanisms. METHODS: Lipopolysaccharide (LPS) induced SAE models were established in mice and primary microglia for the assessment of YTHDF3 and pyroptosis levels. Downstream targets of YTHDF3 were identified through RNA sequencing and RNA immunoprecipitation. Ultimately, chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) was utilized to confirm H3K18la enrichment at the YTHDF3 promoter. RESULTS: In both in vitro and in vivo models of SAE, YTHDF3 expression was significantly upregulated. Crucially, YTHDF3 knockdown effectively attenuated NLRP3-mediated microglial pyroptosis, thereby alleviating neuroinflammation and restoring cognitive function in SAE mice. Mechanistically, Usp9x acted as a direct downstream target of YTHDF3 to mediate the deubiquitination of NLRP3, which in turn augmented microglial pyroptosis in SAE. Furthermore, the transcriptional upregulation of YTHDF3 was promoted by H3K18la enrichment at its promoter. Inhibition of the lactylation-driven YTHDF3/Usp9x/NLRP3 signaling axis attenuates microglial pyroptosis and ameliorates cognitive dysfunction in SAE models. CONCLUSION: Lactylation-driven YTHDF3 promotes microglial pyroptosis and cognitive impairment in SAE by targeting the Usp9x/NLRP3 axis. Our findings highlight this axis as a potential therapeutic target for SAE.