Sex-specific T cell exhaustion drives differential immune responses in glioblastoma

Abstract

Abstract Sex differences in glioblastoma (GBM) incidence and outcome are well recognized; males show higher incidence and worse prognosis than females. Emerging evidence suggests that these extend to genetic/epigenetic and cellular differences, including immune responses. However, the mechanisms driving immunological sex differences are not fully understood. Using orthotopic GBM animal models, we recapitulated these sex differences in immune-competent B6 mice but not in immune-deficient mouse strains (NSG and RAG1KO). By depleting CD8+ T cells, we further confirm that CD8+ T cells play a critical role in driving sex differences in survival. Flow cytometry analysis revealed that male CD8+ T cells from tumor expressed higher levels of exhaustion markers such as PD-1, CTLA-4 and Tox, with higher frequency of progenitor exhausted T cell subset whereas female tumor contained more effector-like CD8+ T cells expressing elevated cytokine production. Anti-PD-1 antibody treatment exclusively extended the survival of male mice via inducing decreased exhausted CD8+ T cell subsets and increased effector function and proliferation. Survival analysis on bone marrow chimera model and adoptive transfer model indicated that T cell-mediated tumor control was predominantly regulated in a cell-intrinsic manner, as the sex of donor cells was a critical contributing factor. Finally, we confirmed these observations in GBM patient tumor samples with male tumors having a higher frequency of progenitor exhausted T cells with increased TOX expression. Taken together, these findings demonstrate sex-specific pre-determined behavior of T cells is critical in inducing sex differences in GBM progression and immunotherapy responses. Supported by grants from NIH (R35 NS127083, P01 CA245705).