Procyanidin B2 ameliorates hypoxic-ischemic brain damage in neonatal rats by inhibiting pyroptosis via the TLR4/NF-κB signaling pathway

Background Neonatal hypoxic–ischemic encephalopathy (HIE) is a major cause of neonatal death and long-term neurodevelopmental impairment. Secondary neuroinflammation and inflammasome-mediated pyroptosis substantially contribute to progressive brain injury. Procyanidin B2 (PCB2), a plant-derived proanthocyanidin abundant in several traditional botanicals, exhibits anti-inflammatory activity, but its role in neonatal hypoxic–ischemic brain injury remains unclear. Objective To determine whether PCB2 protects against neonatal hypoxic–ischemic brain damage (HIBD) in rat and to clarify whether the TLR4/NF-κB pathway–driven pyroptosis is involved. Methods A Rice–Vannucci hypoxic–ischemic brain injury model was established in postnatal day 7 Sprague–Dawley rats. Brain injury was assessed by H&E, Nissl staining, ultrastructural analysis, and long-term behavioral tests at P28. Transcriptomic profiling and enrichment analyses were used to identify key pathways. qRT-PCR, Western blotting, and immunofluorescence were performed to evaluate TLR4/MyD88/NF-κB signaling and pyroptosis markers. TLR4 gain- and loss-of-function experiments were conducted in OGD-injured BV2 microglial cells. Molecular docking was applied to predict the potential PCB2–TLR4 interaction. Results PCB2 markedly reduced histopathological damage and improved P28 cognitive performance, accompanied by restoration of synaptic/neuronal markers. Transcriptomics identified enrichment of Toll-like receptor and cytokine-related inflammatory pathways among PCB2-reversed genes. PCB2 suppressed TLR4/MyD88/NF-κB activation and decreased NLRP3 inflammasome/pyroptosis proteins (NLRP3, ASC, caspase-1, GSDMD-N) and IL-1β/IL-18 (all P < 0.05). TLR4 overexpression attenuated, whereas TLR4 silencing enhanced, PCB2's anti-pyroptotic effects in vitro. Molecular docking predicted a potential interaction between PCB2 and TLR4. Conclusions PCB2 alleviates neonatal hypoxic–ischemic brain injury by inhibiting TLR4/NF-κB–dependent pyroptosis, supporting its potential as a therapeutic candidate for neonatal HIBD.