A high-glucose diet stimulates an anti-tumor immune response to glioblastoma via gut microbiota modulation

A high-sugar diet induces lifestyle-associated metabolic diseases, such as obesity and diabetes, which may underlie the pro-tumor effects of a high-sugar diet. We supplied GL261 syngeneic glioblastoma (GBM) model mice with a short-term high-glucose diet (HGD) and found an increased survival rate with no evidence of metabolic disease. Modulation of the gut microbiota by an HGD was critical for enhancing the anti-tumor immune response. Single-cell RNA sequencing showed that modulation of the gut microbiota by an HGD increased the T cell-mediated anti-tumor immune response in GBM mice. We found that the cytotoxic CD4+ T cell population in GBM mice increased due to synergy with anti-PD-1 immune checkpoint inhibitors, but this depended on an HGD. Thus, we determined that an HGD enhanced anti-tumor immune responses in GBM mice through changes in the gut microbiota and suggest that the role of an HGD in GBM should be re-examined. Overall design: We analyzed glioma infiltrated immune cells by single cell RNA sequencing (scRNAseq) with 10X genomics. For the high glucose diet experimental model, we supplied C57BL/6 wild type mice with 20% dextrose water for 5 weeks before and 2 weeks after GL261 mouse glioma tumor cell inoculation intracranially. Cells in tumor were isolated at 20 days after inoculation and sorted CD45-positive immune cells were analyzed. For Desulfovibrio colonization, we supplied C57BL/6 wild type germ-free mice with Desulfovibrio vulgaris 1 × 10^8 cells/100 µl or DPBS for control through oral gavage, three times a week for 2 weeks before and after GL261 tumor inoculation. Cells in tumor were isolated at 20 days after inoculation and sorted CD45-positive immune cells were analyzed. For anti PD-1 samples, we supplied C57BL/6 wild type mice with 20% dextrose water for 5 weeks before and 2 weeks after GL261 mouse glioma tumor cell inoculation intracranially. For anti-PD-1 ICI administration, 200 µg of anti-mouse PD-1 depletion antibody was injected intraperitoneally into each mouse on days 9, 12, 15 after GL261 tumor inoculation. Cells in tumor were isolated at 20 days after inoculation and sorted CD45-positive immune cells were analyzed.