Baicalin Reduces Immune Cell Infiltration by Inhibiting Inflammation and Protecting Tight Junctions in Ischemic Stroke Injury.

Ischemic stroke is a serious health hazard that lacks effective treatment strategies. This study aims to investigate baicalin's effect on tight junctions and immune cell infiltration after ischemic stroke injury. Rat brain microvascular endothelial cells (BMECs) were treated with OGD/R to establish an in vitro model. Caspase-3, Bax, Bcl-2, zonula occludens-1 (ZO-1), occludin, claudin-5, tumor necrosis factor (TNF)-[Formula: see text], interleukin (IL)-6, inducible nitric oxide synthase (iNOS), Toll-like receptor (TLR) 2, TLR4, and nuclear factor-kappa B (NF-[Formula: see text]B) expressions were detected using qRT-PCR and western blotting. ZO-1, TNF-[Formula: see text], iNOS, IL6, CD31, and ZO-1 expressions were examined using immunofluorescence. A tube formation assay was performed to measure angiogenesis. An ischemia-reperfusion model in rats was established by middle cerebral artery occlusion. The infarct volume was observed using 2,3,5-triphenyltetrazolium chloride staining. TNF-[Formula: see text], iNOS, and IL6 levels in the serum were tested using ELISA. Flow cytometry was performed to examine immune cell inflammatory infiltration. Baicalin had no significant effect on the proliferation of normal BMECs. Baicalin inhibited apoptosis, protected against tight junction injury, and alleviated the inflammatory response in OGD/R-induced BMECs and IR rats, with the highest dose (25[Formula: see text][Formula: see text]g/mL) exerting a superior effect. Baicalin decreased the neurological function score, infarct volume, and brain water content, relieved brain morphological changes, and inhibited immune cell infiltration in vivo. In conclusion, baicalin could reduce BMECs apoptosis, protect tight junctions, and resist immune cell infiltration, thereby alleviating ischemic stroke. Our findings potentially provide a novel treatment strategy for ischemic stroke.