HDAC3 Mediates Hippocampal Microglial Pyroptosis Via the STING/NLRP3 Pathway and Contributes To Cognitive Impairment in Sepsis-Associated Encephalopathy.

Microglial pyroptosis-mediated neuroinflammation emerges as a critical pathogenic mechanism underlying sepsis-associated encephalopathy (SAE). Epigenetic modifications, especially histone acetylation states, exert fundamental regulatory effects on microglial pyroptosis. Among these, histone deacetylase 3 (HDAC3) has been identified as a central epigenetic regulator orchestrating these processes. This study investigates the functional role of HDAC3 in microglial pyroptosis and its underlying mechanisms contributing to SAE-related cognitive impairment. To explore this, male C57BL/6 mice subjected to cecal ligation and puncture (CLP) served as the SAE model. We employed RGFP966, a selective HDAC3 inhibitor, administered at 20 mg/kg/day via daily subcutaneous injections for 14 days starting 2 h prior to CLP surgery. To specifically examine HDAC3's role in microglia, we bilaterally injected recombinant adeno-associated virus (rAAV)-expressing rEGFP under the control of a DIO promoter into the hippocampus of Cx3cr1-Cre mice to achieve selective overexpression. Our data demonstrate that HDAC3 in microglia activates pyroptosis through the STING/NLRP3 pathway, exacerbating oxidative stress responses and impairing neural activity, ultimately leading to cognitive deficits in SAE. Furthermore, HDAC3 overexpression in microglia recapitulates these pathological changes, underscoring its central role in driving disease progression. Conversely, RGFP966 treatment effectively attenuates these abnormalities by suppressing HDAC3 expression and downstream inflammatory pathways. These findings highlight the therapeutic potential of targeting microglial HDAC3 to mitigate neuroinflammation and cognitive dysfunction in SAE, offering a novel direction for future clinical applications.