Electroacupuncture Protects Against Post-stroke Cognitive Impairment by Promoting an IL-33/ST2 Axis-Mediated Microglia M2 Polarization

Abstract

Post-stroke cognitive impairment (PSCI) is a common and debilitating complication of stroke that significantly hinders rehabilitation. Electroacupuncture (EA), which integrates traditional acupuncture with electrical stimulation, has been widely applied in clinical practice and shown remarkable efficacy in treating PSCI. However, its underlying mechanisms remain largely unexplored. The PSCI rat model was established by middle cerebral artery occlusion/reperfusion (MCAO/R). EA treatment commenced 24 h after reperfusion and was administered daily for two weeks. To investigate the role of the Interleukin-33 (IL-33)/Interleukin 1 Receptor-Like 1 (ST2) signaling pathway in EA’s therapeutic effects, the ST2 inhibitor Astegolimab (Anti-ST2) was stereotactically injected into the lateral ventricle prior to EA intervention. Neurological function was evaluated using the Zea-Longa neurological deficit score, while emotional and cognitive behaviors were assessed through the open field test (OFT) and novel object recognition (NOR) test. Cerebral infarct volume was quantified using 2,3,5-triphenyltetrazolium chloride (TTC) staining. Protein expression in the striatum was analyzed by Western blotting and immunofluorescence staining, and structural alterations were examined using hematoxylin–eosin (HE) staining. Microglial polarization in the ischemic penumbra was evaluated via double immunofluorescence staining. Serum levels of inflammatory cytokines, including interleukin (IL)-33, IL-10, IL-4, TNF-α, IL-1β, and IL-6, were determined using enzyme-linked immunosorbent assay (ELISA). EA markedly enhanced learning and memory in stroke rats, upregulated IL-33 expression, promoted M2 microglial polarization, and preserved the integrity of brain white matter. However, blockade of the IL-33/ST2 pathway with Anti-ST2 diminished the therapeutic benefits of EA, aggravated white matter injury and cerebral infarct volume, and amplified the inflammatory response. EA facilitates microglial polarization toward the M2 phenotype via the IL-33/ST2 signaling pathway, strengthens the structural integrity of cerebral white matter, and promotes neurological recovery after ischemic stroke.