Tim-3 Blockade Reverses CD8~+T Cell Exhaustion And Produces Long-term Survival In Mice With Intracranial Gliomas

Objective:To demonstrate the impact of anti-Tim-3 immune therapy that Tim-3 blockade can reverse CD8+T cell exhaustion and produce long-term survival in mice with intracranial gliomas and try to illustrate the possible mechanism of this effect.Methods:Constucted luci-GL261 cells were implanted into brain tissue of female adult C57BL/6 mouse. Then we observed the dynamic changes of neoplasm under the PE.Successful models were randomly divided into two groups: control, Tim-3 blockade group. The process of tumor formation was checked dynamically. Overall survival was quantified. The mice were killed on day 25 after implantation to assess immunologic parameters in the brain/tumor. CD8+T cell to tumor infiltrative T cells ratio were measured under Flow cytometry. The level of positive immune cytokine TNF-? and negative immune cytokine IL-10 in peritoneal blood were measured by ELISA.Results:The C57BL/6 mice were implanted with 1×106 GL261 cells into its brain. After about 26 days, we observed its clininical syndrome and symptum, and then checked the tumor issue through HE staining. Both the clinical manefetation and pathology are specially alike to hunman GBM. Improved survival was demonstrated with anti-Tim-3therapy, compared with the control group: median survival was 34.0 days in the control arm, 49.9 days in the anti-Tim-3 antibody group(P<0.001 by log-rank analysis). Flowcytometry showed a significant increase in the CD8+T cell to tumor infiltrative T cells ratio in mice receiving anti-Tim-3 therapy, compared with the control group: with 38.9%in the anti-Tim-3 antibody arm and 26.6% in the control group,respectively.Immunologic data on day 25 after implantation showed increased positive immune cytokine TNF-? level: with 546.836 pg/ml in the anti-Tim-3 antibody arm and328.108pg/ml in the control group, respectively(P<0.05). And decreased negative immune cytokine IL-10 level, compared with the control arms: with 114.79 pg/ml in the anti-Tim-3 antibody arm and 312.078 pg/ml in the control group, respectively(P<0.05)?Conclusions:In conclusion, anti-Tim-3 antibody therapy can significantly prolong the survival period of murine models in mice with orthotopic brain tumors. The dysfunctional or exhausted CD8+T cell in tumor infiltrating microenvironment can be restored or partially reversed by Tim-3 blockade, which also involved immune cytokine TNF-? and IL-10.These studies provide strong preclinical evidence to support immune trials for the appropriate patient population with gliomas. However, more precised mechanisms still need further illustration.