Targeted inhibition of microglial C5aR1 by PMX205 mitigates post-ischemic stroke neuroinflammation and promotes functional recovery

BACKGROUND: Ischemic stroke constitutes the leading cause of death and disability worldwide. Post-stroke neuroinflammation, a major driver of secondary neurodegeneration, has emerged as a priority therapeutic target. Microglia serve as critical initiators of this neuroinflammatory cascade in ischemic stroke. This study employed single-cell RNA sequencing and functional experiments to identify key regulatory factors in microglia following distinct ischemic stroke subtypes, with the goal of translating these findings into therapeutic targets for clinical application. METHODS: To identify key regulators in ischemic stroke, we mined and analyzed public single-cell RNA sequencing datasets. Two etiologically distinct stroke models were subsequently established: permanent focal ischemia via distal middle cerebral artery occlusion (dMCAO) and transient ischemia-reperfusion injury using middle cerebral artery occlusion/reperfusion (MCAO/R). C5aR1 spatiotemporal expression was quantified through immunofluorescence (cellular localization) and quantitative immunoblotting (temporal dynamics), followed by validation of PMX205-C5aR1 binding affinity via rigid-receptor molecular docking. Therapeutic assessment included acute-phase measurements (3d post-stroke): pro-inflammatory cytokines (ELISA), cerebral infarction volume (TTC staining), and co-quantification of neuronal apoptosis/viability (TUNEL/Nissl); alongside chronic functional recovery tracking (14d): motor coordination (rotarod), sensorimotor integration (adhesive removal test), anxiety-like behavior (open field exploration), and spatial working memory (Y-maze spontaneous alternation). RESULTS: Bioinformatics analysis identified significant upregulation of C5aR1 in activated microglia following ischemic stroke. This finding was corroborated by spatially resolved immunofluorescence and quantitative immunoblotting; molecular docking confirmed stable PMX205-C5aR1 binding via specific hydrophobic interactions, and subsequent therapeutic intervention with PMX205 profoundly suppressed neuroinflammation (IL-1β/IL-6/TNF-α), reduced cerebral infarction, attenuated neuronal apoptosis, and reversed long-term neurological deficits. CONCLUSION: Targeted inhibition of C5aR1 by PMX205 represents a therapeutically viable strategy to attenuate neuroinflammatory cascades and improve long-term functional recovery after ischemic stroke.