Fig. 2

Potential anti-tumor mechanisms of Tregs. A Pro-inflammatory Tregs secrete inflammatory cytokines that have anti-tumor effects. B IL-10 secreted by Tregs promotes the activation of CD8⁺ T cells and induces the production of GzmB and IFN-γ, and further upregulates the expression of MHC molecules. C MCs release mediators that promote tumor metastasis and angiogenesis. Tregs decrease MC numbers and hinder their degranulation by releasing IL-10 and via the OX40-OX40L cell contact mechanism. D Th2 promotes aberrant expression of β-catenin, releases cytokines that activate M2 macrophages, and promotes tumor-associated fibrous capsule development, whereas Th17 releases cytokines that stimulate tumor angiogenesis and progression. Tregs suppress the pro-tumor inflammatory response induced by Th2, Th17, and M2 macrophages. E Tregs promote the differentiation of fibroblasts to myofibroblasts by releasing TGF-β, in turn suppressing tumor growth. Depletion of Tregs cells leads to an increase in the accumulation of fibroblasts and the recruitment of tumor-promoting Arg1⁺ Mφ cells