SIRT2 Promotes NLRP3-Mediated Microglia Pyroptosis and Neuroinflammation via FOXO3a Pathway After Subarachnoid Hemorrhage

Purpose: This study primarily elucidating the specific mechanism of SIRT2 on neuroinflammation and microglial pyroptosis in a mouse model of SAH.

Patients and methods: CSF were collected from 57 SAH patients and 11 healthy individuals. C57BL/6 mouse SAH model was established using prechiasmatic cistern blood injection and the in vitro hemoglobin (Hb) stimulation microglia model. Lentivirus was used as a vector for RNA interference technology to knock down the SIRT2 gene expression. Small interfering RNA was used to knockdown the expression of FOXO3a. The tools included measurements of brain water content, neurological scores, Western blot, PCR, ELISA, TEM, immunofluorescence, LDH assay, modified Garcia score, and balance beam tests to evaluate changes in pyroptosis and neuroinflammatory responses.

Results: In CSF samples from SAH patients, elevated levels of SIRT2 and GSDMD were observed, with SIRT2 demonstrating particular diagnostic value for predicting prognosis at the 3-month follow-up. SIRT2 upregulation exacerbated neurological deficits, brain edema, and blood-brain barrier disruption in mice following SAH. SIRT2 increased GSDMD, caspase-1, and IL-1β/IL-18 expression, and amplified GSDMD-positive microglia. FOXO3a was also upregulated post-SAH. siRNA-mediated SIRT2 knockdown ameliorated microglial pyroptosis after SAH. FOXO3a siRNA reduced NLRP3 inflammasome activation and microglial pyroptosis severity, along with neuroinflammation post-SAH.

Conclusion: In summary, SIRT2 promoted microglial pyroptosis, primarily by increasing the expression and activity of Foxo3a, thereby exacerbating neuroinflammatory damage following subarachnoid hemorrhage.