- Wang, Qirui;
- He, Zhenqiang;
- Huang, Menggui;
- Liu, Tianrun;
- Wang, Yanling;
- Xu, Haineng;
- Duan, Hao;
- Ma, Peihong;
- Zhang, Lin;
- Zamvil, Scott S;
- Hidalgo, Juan;
- Zhang, Zhenfeng;
- O’Rourke, Donald M;
- Dahmane, Nadia;
- Brem, Steven;
- Mou, Yonggao;
- Gong, Yanqing;
- Fan, Yi
Spatiotemporal regulation of tumor immunity remains largely unexplored. Here we identify a vascular niche that controls alternative macrophage activation in glioblastoma (GBM). We show that tumor-promoting macrophages are spatially proximate to GBM-associated endothelial cells (ECs), permissive for angiocrine-induced macrophage polarization. We identify ECs as one of the major sources for interleukin-6 (IL-6) expression in GBM microenvironment. Furthermore, we reveal that colony-stimulating factor-1 and angiocrine IL-6 induce robust arginase-1 expression and macrophage alternative activation, mediated through peroxisome proliferator-activated receptor-γ-dependent transcriptional activation of hypoxia-inducible factor-2α. Finally, utilizing a genetic murine GBM model, we show that EC-specific knockout of IL-6 inhibits macrophage alternative activation and improves survival in the GBM-bearing mice. These findings illustrate a vascular niche-dependent mechanism for alternative macrophage activation and cancer progression, and suggest that targeting endothelial IL-6 may offer a selective and efficient therapeutic strategy for GBM, and possibly other solid malignant tumors.