TGFB1 and glioma: MDSCs mediate immunosuppression by suppressing the function of cytotoxic T cells, NK cells, anti-inflammatory macrophages, and dendritic cells through the production of nitric oxide and various immunosuppressive cytokines, such as IL-10 and TGF-β [48,49,50] Further, they promote the recruitment of Tregs, B cells and M2 macrophages, which contribute to high-grade glioma progression [49,51].