Etomidate protects against homocysteine-induced blood-brain barrier disruption via upregulation of Krüppel-like factor 2

As the second leading cause of death, stroke has a significant impact on public health. Homocysteine (Hcy), a non-essential sulfur-containing amino acid, has recently been found to aggravate brain injury in stroke. This effect is closely associated with oxidative stress (OS), blood-brain barrier (BBB) dysfunction, and endothelial cell damage. Etomidate, originally developed as a sedative, has demonstrated strong protective effects against OS and inflammation. However, its role in stroke remains underexplored. Our research aimed to investigate the potential effects of etomidate in treating Hcy-induced stroke. In C57BL/6 mice, Hcy (0.03 µmol/g, subcutaneous) was administered for one month alongside etomidate (3 mg/kg, intraperitoneal). BBB permeability was assessed via sodium fluorescein diffusion, while OS (GSH, MDA) and inflammation (TNF-a, IL-1b) were measured using spectrophotometry and ELISA. Occludin and KLF2 expression were analyzed by Western blot and immunostaining. In vitro, human brain microvascular endothelial cells (HBMVECs) were treated with Hcy (20 µM) and etomidate (2.5-5 µM), with barrier integrity evaluated via FITC-dextran assay and transepithelial/transendothelial electrical resistance (TEER) measurements. KLF2 knockdown was performed using lentiviral shRNA to confirm its mechanistic role. Hcy-challenged mice exhibited significantly decreased reduced GSH levels, increased MDA, TNF-a, and IL-1b levels, enhanced diffusion of sodium fluorescein, and reduced occludin expression. These changes were notably reversed by etomidate. In vitro, primary HBMVECs were stimulated with 20 µM Hcy, with or without etomidate (2.5 or 5 µM) for 24 hours. Hcy-treated HBMVECs showed significantly increased FITC-dextran intensity, decreased TEER, reduced occludin expression, and diminished KLF2 levels. These effects were notably reversed by etomidate. Moreover, the protective effects of etomidate on Hcy-induced occludin reduction and increased endothelial monolayer permeability were negated by KLF2 inhibition. In conclusion, etomidate exerts protective effects against Hcy-induced BBB disruption by upregulating KLF2.