MPO and stroke disorder: In contrast, neutrophils regulate neuroinflammation after stroke through various inflammatory mediators, such as neutrophil protease (NE), myeloperoxidase (MPO), MMP, tissue inhibitors of metalloproteinase (TIMP), IFN, and IL (Cai et al., 2020), especially the expression of MMP can directly destroy the blood-brain barrier, leading to secondary brain injury or hemorrhagic transformation (McColl et al., 2008).