Hyperforin has been shown to be capable of promoting angiogenesis and functional recovery after
ischemic stroke in our previous study. However, the exact mechanisms involved are not fully elucidated. In this study, adult male mice were subjected to 60-min transient
middle cerebral artery occlusion followed by reperfusion for 28 days.
Hyperforin was administrated to MCAO mice every 24 h for 2 weeks starting at 14 days post-
ischemia (dpi). Then flow cytometry, quantitative Real-time PCR (RT-qPCR), western blotting, immunohistochemistry, and functional assays were performed to explore the molecular mechanisms in vivo and in vitro. Our data showed that
hyperforin increased astrocytic
interleukin (IL)-6 in the ischemic hemisphere via TLR4 at 28 dpi. The astrocytic
IL-6 was essential to the promoting effects of
hyperforin on the neural precursor cells proliferation, neuronal differentiation, angiogenesis, and functional recovery after
stroke. Furthermore,
hyperforin promoted the infiltration of regulatory T cells (Tregs) to the ischemic hemisphere and increased Tregs-derived
cytokine IL-10 and
transforming growth factor-β (TGF-β) in a manner that was dependent on astrocytic
IL-6. Astrocytic
IL-6 was critical to the role of
hyperforin in promoting the infiltration of T-helper (Th) type 2 cells to the ischemic hemisphere and Th2-derived
cytokine IL-4, relative to Th1 and Th1-derived
cytokine interferon-γ (IFN-γ), which decreased during
stroke recovery. After depletion of CD25+ Tregs, the promoting effects of
hyperforin on post-
stroke neurogenesis was attenuated. Moreover, blockade of
IL-4 and TGF-β abrogated the promoting role of
hyperforin in post-
stroke neurogenesis, angiogenesis and functional recovery. Our results reveal a previously uncharacterized role of astrocytic IL-6-mediated negative immune regulation in the promoting effects of
hyperforin on post-
stroke neurovascular regeneration and functional recovery.