Forsythoside A Alleviates Neuroinflammatory Damage via Inhibiting <scp>TLR4</scp> / <scp>NF</scp> ‐ <scp>κB</scp> / <scp>NLRP3</scp> Activation‐Induced Astrocyte Pyroptosis in Cerebral Ischemia–Reperfusion

BACKGROUND: The neuroinflammatory cascade triggered by cerebral ischemia-reperfusion injury (CIRI) represents a pivotal pathological mechanism driving neuronal death and dysfunction. Forsythoside A (FA) exhibits anti-inflammatory properties, but its effects on CIRI and potential mechanisms remain unclear. AIMS: To investigate whether FA improves astrocyte pyroptosis and alleviates neuroinflammatory damage in CIRI via modulating the Toll-like receptor 4 (TLR4)/nuclear factor κB (NF-κB)/NLRP3 pathway. METHODS: The middle cerebral artery occlusion reperfusion (MCAO/R) mouse model was established, with cerebral infarction volume observed through TTC staining, and neurological scores assessed. The effects of FA on cerebral cortical damage, neuroinflammation, apoptosis, and pyroptosis were observed by pathological staining. An oxygen-glucose deprivation/reoxygenation (OGD/R) U251 human astroglioma cell model was established, and the protective impact of FA on cell viability was detected through the cell counting kit-8 assay. The release of lactate dehydrogenase (LDH) was measured by the LDH assay Kit, and cell pyroptosis was evaluated through Hoechst 33,342/PI staining. Inflammatory factor levels were detected by ELISA kits, with pyroptosis-related and TLR4/NF-κB/NLRP3 pathway-related protein levels evaluated through Western blot. RESULTS: FA reduced the infarct volume, ameliorated brain tissue pathological damage, reduced activated astrocytes, and inhibited neuronal apoptosis in MCAO/R mice. FA also alleviated inflammatory cell infiltration in brain tissue and declined pro-inflammatory factor levels in serum. In addition, FA suppressed TLR4 and p-NF-κB p65 expression and NLRP3 inflammasome activation in astrocytes. OGD/R caused decreased U251 cell viability, increased LDH release, and pyroptosis rate, while FA treatment could reverse the above effects. Mechanistically, FA hindered the TLR4/NF-κB pathway, down-regulated NLRP3 and pyroptosis-related proteins. The TLR4 agonist LPS weakened the protective impact of FA on MCAO/R mice and OGD/R cell models. CONCLUSION: FA alleviates neuroinflammatory damage through inhibiting the TLR4/NF-κB axis and blocking NLRP3 inflammasome-induced astrocyte pyroptosis.