Interleukin-33 improves the neurogenesis of neural stem cells in perinatal brain after hypoxia-ischemia.

Perinatal hypoxia-ischemia (HI) insult is an important cause of neonatal encephalopathy, and the effective therapeutic approaches are currently limited. Interleukin (IL)-33 acts as a member of the IL-1 superfamily and has been shown to be neuroprotective following experimental neonatal HI and adult stroke. Here, we explore the effect of IL-33 and its specific receptor ST2 axis on endogenous neurogenesis in neonatal brain after HI. ST2 was found on the surface of NSCs, and the expression of ST2 was further enhanced after HI challenge. Delivery of IL-33 obviously repopulated the size of NSC pool, whereas ST2 deficiency worsened the neurogenesis of NSCs in neonatal brain post HI insult. Further in vivo and in vitro studies showed IL-33 regulates the survival, proliferation and differentiation of NSCs through ST2 signaling pathways. Intriguingly, IL-33 facilitated translocation of Nrf2 from the cytoplasm to the nucleus, which is involved in neural differentiation of NSCs. These data demonstrate a critical role of IL-33/ST2 axis in regulation of endogenous neurogenesis of NSCs via activation of the Nrf2 signaling, which provide a new insight into the effect of IL-33 in neonatal brain following HI injury.