Metalloproteinase (MMP)9 plays a pivotal role in ischemic stroke induced blood brain barrier (BBB) disruption. Correlation between HSP90 and MMP9 in several diseases prompted us to evaluate the efficacy of HSP90 inhibition as a novel approach to protect BBB integrity in ischemic stroke. ELISA was used to detect HSP90α and MMP9 in serum samples of stroke patients, which showed that HSP90α significantly correlated with MMP9 among 63 serum samples of stroke patients. Male C57/BL6 mice were pretreated with 17-Dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG) or vehicle before being subjected to transient occlusion of middle cerebral artery and reperfusion (MCAO). Infarction, neurological scores, Evans blue (EB) extravasation, inflammatory responses and tight junction protein expression were examined 24 h after MCAO. We also investigated if 17-DMAG protected BBB integrity by suppressing inflammation and MMP9 activation. Oxygen glucose deprivation (OGD) was performed on bEnd.3 cells to explore the mechanisms of HSP90 inhibition in inhibiting MMP9. The results demonstrated that infarct volume was reduced in 17-DMAG-treated mice compared to control group following MCAO. Neurological outcomes were greatly improved in 17-DMAG-treated mice. Inflammatory responses, MMP9 activity and EB extravasation were decreased by 17-DMAG. In addition, 17-DMAG inhibited nuclear factor kappa B (NF-κB) activation following MCAO. Furthermore, HSP90 inhibition decreased NF-κB dependent MMP9 expression in bEnd.3 after OGD /reoxygenation. These findings suggested that HSP90 could be a novel therapeutic target in BBB breakdown during ischemic stroke. As several HSP90 inhibitors are in clinical trials for cancer, these findings have translational implications.
Keywords: Blood brain barrier; heat shock protein 90; inflammation; ischemic stroke.