Brain border-derived CXCL2 neutrophils drive NET formation and impair vascular reperfusion following ischemic stroke.

Background: The brain border compartments harbor a diverse population of immune cells and serve as invasion sites for leukocyte influx into the brain following CNS injury. However, how brain-border myeloid cells affect stroke pathology remains poorly characterized.

Methods And Results: Here, we showed that ischemic stroke-induced expansion of CXCL2 neutrophils, which exhibit highly proinflammatory features. We tracked CXCL2 neutrophils in vivo by utilizing a photoconvertible Kik-GR mouse (fluorescent proteins Kikume Green Red, Kik-GR) and found that brain-infiltrating CXCL2 neutrophils following ischemic stroke were mainly derived from the brain border rather than the periphery. We demonstrated that CXCL2 neutralization inhibited the formation and releasing of neutrophil extracellular traps (NETs) from in vitro cultured primary neutrophils. Furthermore, CXCL2-neutralizing antibody treatment reduced brain infarcts and improved vascular reperfusion at day 3 postischemic stroke.

Conclusions: Collectively, brain border-derived CXCL2 neutrophil expansion may impair vascular reperfusion by releasing NETs following ischemic stroke.