Fig 2: IL-6 neutralization and CD40 stimulation sensitizes GBM to immune checkpoint blockade treatment.GBM was induced in mice by transplantation with a–c, tumor cells derived from RCAS-genetically engineered model (n = 6–7 mice, specific n numbers are shown in the figure) or d–f GL261 tumor cells (n = 8–9 mice, specific n numbers are shown in the figure), followed by different treatment and survival analyses. a, d Experimental procedure. b, e Tumor volume was analyzed by bioluminescence imaging. c, f Mouse survival was monitored and analyzed by two-sided Log-rank Mantel–Cox analysis. MS, median survival. Source data are provided as a Source data file.

Fig 3: GBM ECs express IL-6. a Human brain ECs were treated with glioma-CM for 24 h, and cell lysates were subjected to multiplex cytokine array analysis. Left, a representative blot. Right, quantified dot intensity of most significantly changed cytokines. b Human microvascular brain ECs were treated with glioma-CM that were harvested from different human glioma cells. Cell lysates were immunoblotted. c Human microvascular brain ECs and tumor-associated ECs isolated from different GBM patients were subjected to immunoblot analysis. d Mouse GBM was induced by orthotopic injection of GL26 glioma cells into wild-type mouse. The brain sections that include normal brains and tumors were stained with anti-CD31, anti-IL-6, and anti-CSF-1 antibodies. Representative immunofluorescence images are shown. Right, enlarged area in normal and tumor tissues. Bar represents 50 µm. Zoom-in factor: 4

Fig 4: A schematic model. In glioma microenvironment, endothelial cell-derived IL-6 and microenvironmental CSF-1 synergistically activate downstream Akt1/mTOR pathway and induces transcriptional activation of PPAR? in macrophages (M?), in turn leading to HIF-2a-mediated arginase-1 expression, and inducing macrophage alternative polarization. The activation of mTOR also induces cell proliferation, contributing to cell survival and growth of alternatively activated macrophages, eventually leading to glioma progression

Fig 5: PPAR? induces HIF-2a and arginase-1 expression in macrophages. a, b Mouse BM-derived macrophages were treated with or without CSF-1 and IL-6 for 5 days. a Cell lysates were immunoblotted. b mRNA was extracted and subjected to quantitative RT-PCR analysis. Results were normalized with GAPDH level and expressed as folds of control (n = 3, mean ± SEM). P value was determined by Student’s t test. c, d Mouse BM-derived macrophages were treated with or without CSF-1 and IL-6 for 3 days. c Nuclei protein was incubated with biotin-labeled synthetic DNAs that encode control scrambled or HIF-2a promoter sequence, followed by immunoprecipitation with streptavidin-conjugated beads. Precipitants and nuclei protein were immunoblotted. d Nuclei extracts were subjected to chromatin immunoprecipitation (ChIP) analysis. Immunoprecipitants with control IgG or anti-PPAR? antibody were analyzed by PCR and electrophoresis (upper) or by quantitative PCR (bottom, n = 3, mean ± SD). e Mouse BM-derived macrophages were transduced with lentivirus that expresses shRNAs targeting control scrambled sequence and PPAR? (#1657, #1660, and #25967), followed by treatment with CSF-1 and IL-6 for 10 days. Cells were lysed and subjected to immunoblot analysis. f Mouse BM-derived macrophages were treated with or without CSF-1 and IL-6. At different time points post-treatment, cells were lyzed and subjected to immunoblot analysis. Band density was quantified. g Mouse BM cells were pretreated with or without rapamycin, followed by incubation with CSF-1 and IL-6. Cell viability was determined (n = 3 mice, mean ± SEM)