Oseltamivir Phosphate Modulates CD24-Siglec-G/10 Interaction to Suppress Microglial-Driven Neuroinflammation After Cardiac Arrest.

BACKGROUND: In cardiac arrest (CA) patients undergoing cardiopulmonary resuscitation (CPR), neuroinflammation following return of spontaneous circulation (ROSC) contributes to brain ischemia/reperfusion injury and neurological dysfunction. Recent evidence suggested that neuraminidase could exacerbate inflammatory responses by disrupting CD24-Siglec-G/10 immune checkpoint axis. As a neuraminidase inhibitor, oseltamivir phosphate (OP) holds potential for immunomodulation beyond its antiviral use. We aimed to investigate the impact and mechanism of OP on neuroinflammation regulation after ROSC. METHODS: Male pigs were randomized into the sham control group, CPR, and CPR + OP group. CA was induced in pigs through 8 min of untreated ventricular fibrillation. Brains were harvested for assessing serum inflammatory markers and neuronal damage at 24 h after ROSC. BV2 microglial underwent oxygen-glucose deprivation/reperfusion (OGD/R). Effects of OP on inflammatory responses, NF-κB activation, cell viability, and the CD24-Siglec-G/10 interaction were evaluated using immunofluorescence, immunoprecipitation, molecular, and biochemical assays. RESULTS: In vivo, OP attenuated pig cerebral microglial activation and neuronal integrity with attenuated neuroinflammation, alongside time-dependent neuraminidase activity increases. In vitro, OP suppressed OGD/R-induced microglial NF-κB activation, reduced pro-inflammatory cytokine levels, and preserved CD24-Siglec-G interaction, correlating with diminished neuraminidase release. CONCLUSIONS: OP as a repurposed immunomodulator that suppresses microglial-driven neuroinflammation after CA by preserving sialylation-dependent CD24-Siglec-G/10 interaction.