Icariside Ⅱ preconditioning evokes robust neuroprotection against
ischemic stroke: Targeting Nrf2 mediated by OXPHOS/NF-κB/ferroptosis
pathway
Abstract
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.