Abstract DP392: Prdx1-Mediated Antioxidant and Neuroprotective Roles of Stroke-Associated Microglia

Ischemic stroke, a leading cause of global morbidity and mortality, is largely driven by oxidative stress from reactive oxygen species (ROS) during ischemia/reperfusion (I/R) injury. Microglia, the brain's resident immune cells, mediate early responses to such oxidative stress, yet the molecular identity of neuroprotective microglial subsets remains incompletely defined. To characterize this heterogeneity, we performed single-cell RNA sequencing (scRNA-seq) and multiome profiling of brain cells following I/R injury.To elucidate the in vivo role of Prdx1 , we conducted transient middle cerebral artery occlusion (tMCAO) in both Prdx1 -deficient and wild-type mice. Deletion of Prdx1 resulted in a pronounced increase in infarct size, a substantial depletion of the SAM population, extensive microglial cell death, and amplified neuroinflammatory responses within the ipsilateral hemisphere 1 day after stroke onset. Furthermore, Prdx1 -expressing SAMs exhibited upregulation of neuroprotective molecules such as osteopontin and ferritin, highlighting their critical contribution to mitigating acute-phase ischemic injury. We identified a distinct microglial population, termed stroke-associated microglia (SAM), enriched in antioxidant genes including Peroxiredoxin-1 (Prdx1), Txn1, Srx1, Mt1, and Mt2, partially overlapping with previously described disease-associated microglia (DAM). In vivo, transient middle cerebral artery occlusion (tMCAO) in Prdx1-deficient mice led to larger infarcts, depletion of SAMs, increased microglial death, and heightened neuroinflammation compared to wild-type controls. Prdx1+ SAMs upregulated neuroprotective factors such as osteopontin and ferritin, highlighting their critical role in mitigating acute ischemic injury. Single-nucleus multiomic analysis at day 3 post-stroke revealed that SAM-like microglia persist into the subacute phase, maintaining transcriptional and epigenetic signatures consistent with antioxidant activity. Trajectory analysis suggested that SAMs arise from endogenous microglia in response to sustained injury cues. These findings indicate that SAMs contribute to both acute and subacute neuroprotection, emphasizing the importance of further exploring their role in stroke recovery.