Abstract DP037: Route-Dependent Neuroinflammation Remodeling and Neurorepair by Probiotic-Derived Extracellular Vesicles After Ischemic Stroke

Background: Extracellular vesicles (EVs) from Akkermansia muciniphila (Akk-EVs) modulate immunity and repair intestinal injury, but their role in stroke is unclear. We examined their efficacy in ischemic stroke (IS), comparing intragastric (IG) versus intravenous (IV) delivery and underlying mechanisms. Methods: In a clinical cohort, fecal Akk-EV levels were measured in 30 IS patients and 15 healthy controls, and compared between patients with and without neurological deterioration (NIHSS). In mice, photothrombotic middle cerebral artery occlusion (pMCAO) was followed by IG or IV Akk-EV treatment. Biodistribution was assessed using DiR-labeled Akk-EVs and in vivo imaging. Neurological and cognitive functions were evaluated for 14 days; infarct volume, gut microbiota, plasma metabolites, RNA-seq, and scRNA-seq were analyzed. Histology, immunofluorescence, and Western blotting assessed neuroinflammation, glial activation, white matter integrity, and axonal/myelin repair. Results: Clinically, Akk-EV levels were significantly lower in IS patients than controls, and lowest in deteriorating cases. In mice, both IG and IV Akk-EVs improved neurobehavioral and cognitive outcomes, but only IV reduced infarct volume. Biodistribution studies revealed limited brain penetration after IG, with signal confined to the gut, whereas IV delivery achieved robust brain accumulation, peaking at 12h post-injection, and colocalizing predominantly with astrocytes in the ischemic region. scRNA-seq demonstrated that IV Akk-EVs reduced microglial abundance, shifted microglia toward an anti-inflammatory phenotype, suppressed sphingolipid biosynthesis, and enhanced phagocytosis-related phospholipid pathways. In astrocytes, IV treatment modulated oxidative phosphorylation, glycolipid metabolism, and ferroptosis, while promoting gluconeogenesis. IV Akk-EVs increased pericytes, oligodendrocytes, and OPCs, enhanced axonal density, and restored myelin. Cell–cell interaction analysis indicated IV Akk-EVs activated the astrocyte-derived pleiotrophin (PTN)–PTPRZ1 signaling axis to drive OPC differentiation and remyelination. Conclusion: This study demonstrates that IV, but not IG, Akk-EVs efficiently cross the BBB, modulate neuroinflammation, and activate astrocyte–OPC signaling to enhance myelin repair, resulting in superior recovery after IS. As a scalable probiotic-derived therapy, IV Akk-EVs represent a novel, mechanism-based strategy with strong translational potential for stroke repair.