C3aR inhibition alleviates cerebral ischemia-reperfusion injury via STING-mediated ferroptosis through SLC7A11/GPX4

Cerebral ischemia-reperfusion injury couples complement activation with innate immune signaling and ferroptotic lipid peroxidation. We investigated whether C3aR signaling modulates stimulator of interferon genes (STING)-associated ferroptosis through the solute carrier family 7 member 11 (SLC7A11)/glutathione peroxidase 4 (GPX4) anti-ferroptotic pathway. In rat middle cerebral artery occlusion/reperfusion (MCAO/R) and BV2 oxygen-glucose deprivation/reperfusion (OGD/R) models, C3aR blockade with SB290157 was examined with 2'3'-cGAMP-mediated STING activation, immunofluorescence, western blotting, reverse transcription quantitative PCR (RT-qPCR), ferroptosis assays, and molecular docking, molecular dynamics (MD), and molecular mechanics/generalized Born surface area (MM/GBSA) analyses. C3aR inhibition improved neurological outcomes, limited infarction and edema, preserved mitochondrial membrane potential, reduced microglia-associated STING activation and ferroptosis-related Fe²⁺, reactive oxygen species (ROS), and 4-hydroxynonenal (4-HNE) accumulation, and restored SLC7A11 and GPX4 expression; these effects were partly reversed by STING activation. Structural analyses provided supportive evidence for potential STING-SLC7A11/GPX4 interactions. These findings position C3aR-STING signaling as a complement-linked mechanism regulating ferroptosis and suggest a potential therapeutic direction for limiting reperfusion-associated injury after ischemic stroke.