polysaccharide mitigates acute neuroinflammation in cerebral ischemia-reperfusion injury through Csf3-modulated pathways.

Abstract

INTRODUCTION: Microglial hyperactivation-driven neuroinflammation is a major driver of secondary brain injury following cerebral ischemia/reperfusion (I/R), yet effective therapies targeting this pathological process remain limited. Marine-derived sulfated polysaccharides have emerged as promising anti-inflammatory agents, but the therapeutic potential and mechanisms of Laminaria japonica polysaccharide (LJP) in cerebral I/R injury are poorly understood. METHODS: LJP was isolated from Laminaria japonica and structurally characterized via high-performance gel permeation chromatography (HPGPC), Fourier-transform infrared (FT-IR) spectroscopy, and ion chromatography. Its neuroprotective effects were evaluated in a mouse model of transient middle cerebral artery occlusion (tMCAO), with assessments of infarct volume, neurological function, and neuroinflammatory markers. Cross-species transcriptomic analysis identified potential targets, which were validated throughandfunctional assays (rescue experiments with recombinant Csf3 and neutralization assays with Csf3-specific antibodies). RESULTS: Structural characterization confirmed LJP is enriched in fucose, galacturonic acid, glucuronic acid, and sulfate groups. In tMCAO mice, LJP administration reduced infarct volume, improved neurological function, and suppressed microglial pro-inflammatory polarization, accompanied by decreased levels of interleukin-1b (IL-1b), tumor necrosis factor-α (TNFα), and interleukin-6 (IL-6). Transcriptomic analysis identified granulocyte colony-stimulating factor (Csf3/G-CSF) as a potential LJP-regulated mediator. Recombinant Csf3 partially reversed LJP's protective effects, while Csf3-specific antibodies failed to enhance LJP's anti-inflammatory benefits, suggesting Csf3 as an important contributory mechanism. DISCUSSION: These findings demonstrate that LJP mitigates acute neuroinflammation post-I/R at least partly through Csf3 suppression, highlighting its promise as a novel phytotherapeutic agent for ischemic stroke.