Figure 1.

Schematic representation of the proposed roles of neutrophils/tumor-associated neutrophils (TANs) in the glioma microenvironment (GME). Neutrophils can be polarized into two distinct functional phenotypes under certain cytokines and growth factors in the GME, i.e., N1 neutrophils can polarized into N2 in the presence of TGF-β, while N2 neutrophils can polarized into N1 phenotype in the presence of IFN-β. N1 phenotype has been shown to induce tumor cells cytotoxicity/apoptosis, antibody-dependent cellular cytotoxicity (ADCC), activate T cells and inhibit tumor growth. N2 phenotype promoted the tumor growth, stemness, angiogenesis, invasion, and suppress immunity. NE: neutrophil elastase, TNFα: tumor necrosis factor alpha, H₂O₂: hydrogen peroxide, MMP9: matrix metallopeptidase 9, NO: nitric oxide, and NOS2: nitric oxide synthase 2.