Background and Purpose: Blood-brain barrier (BBB) breakdown is one of the most crucial pathological changes of cerebral ischemia-reperfusion (I/R) injury. Trilobatin (TLB), a naturally occurring food additive, exerts neuroprotective effect against cerebral I/R injury as demonstrated in our previous study. This study was designed to investigate the effect of TLB on disruption of BBB after cerebral I/R injury. Experimental Approach: Rats with focal cerebral ischemia caused by transient middle cerebral artery occlusion (MCAO) and brain microvascular endothelial cells along with human astrocytes to mimic blood brain barrier (BBB) injury caused by oxygen and glucose deprivation (OGD) followed by reoxygenation (OGD/R). Key results: The results showed that TLB effectively maintained the integrity of BBB and inhibited neuronal loss following cerebral I/R challenge. Furthermore, TLB dramatically increased tight junction proteins including ZO-1, occludin and claudin 5, as well as decreased the levels of apolipoprotein E (APOE) 4, cyclophilin A (CypA), and phosphorylated nuclear factor kappa B (NF-κB), thereby reduced proinflammatory cytokines. In addition, TLB also decreased Bax/Bcl-2 ratio and cleaved-caspase 3 level along with reduced the number of apoptotic neurons. Intriguingly, molecular docking and transcriptomics predicted MMP9 was a prominent gene evoked by TLB treatment. Furthermore, the protective effect of TLB on OGD/R-induced the loss of BBB integrity in human brain microvascular endothelial cell and astrocyte co-cultures in vitro was markedly reinforced by knockdown of MMP9. Conclusions and implications: Our findings reveal a novel property of TLB: saving BBB disruption following cerebral I/R via targeting MMP9 and inhibiting APOE4/CypA/NF-κB axis.

Background and Purpose: Astrocytic nuclear factor erythroid-derived 2-related factor 2 (Nrf2) is a potential therapeutic target of ischemic preconditioning (IPC). Icariside Ⅱ (ICS Ⅱ) is a naturally occurring flavonoid derived from Herba Epimedii with Nrf2 induction potency. This study was designed to clarify whether ICS Ⅱ simulates IPC neuroprotection and to decipher if the astrocytic-Nrf2 is contributed to ICS Ⅱ preconditioning against ischemic stroke. Experimental Approach: Mice with transient middle cerebral artery occlusion (MCAO)-induced focal cerebral ischemia and oxygen-glucose deprivation (OGD)-injured primary astrocytes were used to explore the neuroprotective of ICS Ⅱ preconditioning. Additionally, Nrf2-deficient mice were pretreated with ICS Ⅱ to determine whether ICS Ⅱ exerts its neuroprotection by activating Nrf2. Key results: ICS Ⅱ pre-treatment dramatically mitigated the cerebral injury in ischemic stroke mice along with restoring long-term recovery. Furthermore, proteomics screening identified Nrf2 is a crucial gene evoked by ICS Ⅱ stimulation and is required for the anti-oxidative effect and anti-inflammatory effect of ICS Ⅱ. Most interestingly, ICS Ⅱ directly bound with Nrf2 and reinforced the transcriptional activity of Nrf2 after MCAO. Moreover, ICS Ⅱ pre-treatment exerted cytoprotective effect on astrocytes after lethal oxygen-glucose deprivation insult via promoting Nrf2 nuclear translocation and mediating OXPHOS/NF-κB/ferroptosis axis. While, abrogated neuroprotection in Nrf2-deficient mice and astrocyte potently supports Nrf2-dependent neuroprotection of ICS Ⅱ. Conclusions and implications: ICS Ⅱ preconditioning confers robust neuroprotection against ischemic stroke via astrocytic Nrf2-mediated OXPHOS/NF-κB/ferroptosis axis, it is concluded that ICS Ⅱ will be serve as a promising Nrf2 activator to rescue ischemic stroke.