Carvalho, Igor Santiago de

Abstract Introduction Immunotherapy approaches against glioblastoma (GBM) such as immune checkpoint inhibitors (ICI), dendritic cell vaccination, and CAR-T have failed to durably cure most patients. Studies analyzing tumors from ICI responders show that abundance of CD4 and CD8 T cells prior to initiation of therapy predicts responsiveness. Thus, targeting the microenvironment to promote CD4 activity may synergize with ICI. The glioblastoma microenvironment contains high proportions of monocyte-derived macrophages which have potent immunosuppressive capabilities. Characterizing and targeting these immunosuppressive programs is a promising strategy for designing effective combination immunotherapies for glioblastoma patients. Methods We analyzed human glioblastoma snRNAseq datasets to find signaling receptors associated with myeloid immunosuppression and employed murine models of glioblastoma for functional validation. Results By analyzing patient-derived -omics datasets, we identified an understudied TNF-superfamily receptor, Fn14, as being upregulated in glioblastoma-associated myeloid cells with immunosuppressive gene signatures. Using in vitro approaches, we found that Fn14 activation in the tumor microenvironment can drive cytokines implicated in GBM immunosuppression such as IL6, IL1B, and IL8. Thus, Fn14 may serve as a surface marker for microenvironment-remodeling myeloid cells recruited to the tumor from peripheral circulation. Furthermore, in murine models of glioblastoma, we discovered Fn14 KO among glioblastoma-associated myeloid cells increases conventional dendritic cell type 1 (cDC1) and Th1 CD4+ T cell abundance in the tumor microenvironment and significantly prolongs survival. Conclusion These results suggest that blocking Fn14 in glioblastoma-associated myeloid cells can enhance Th1 immunity. Thus, Fn14 may represent a promising dual therapy target. Funding Source NIH Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Abstract Memory CD8+ T cells protect against secondary viral infections. They develop and maintain exclusively in circulation (e.g. central memory - Tcm) or are excluded from re-circulation (resident memory - Trm). Circulating memory CD8+ T cells arises from memory precursors (MPs) which express memory, pro-survival, and pluripotency molecules. Trm generation, in contrast, is still not fully understood. Previous reports suggest that Trm and Tcm have a common precursor present at the early effector phase; yet, the nature of this precursor is elusive. We have found that the extracellular ATP receptor P2RX7 promotes both Tcm and Trm generation. Moreover, P2RX7 is quickly upregulated in some (but not all) early effectors and early P2RX7 ablation hinders both Tcm and Trm generation. Thus, we postulated that P2RX7 in early effectors may mark a Tcm/Trm common precursor. Comparison between high (P2RX7hi) and low (P2RX7lo) P2RX7-expressing CD8+ T cells shows a correlation between memory markers and P2RX7, with CD62L+ Tcm precursors exclusively found in P2RX7hi cells. RNA-seq of P2RX7hi and P2RX7lo early effectors show survival, memory and pluripotency genes and pathways are upregulated in P2RX7hi cells. Conversely, many terminal effector and apoptosis genes are upregulated in P2RX7lo cells. P2RX7lo early effectors and MPs have increased apoptosis. Upon transfer into infection-matched mice, P2RX7hi MPs preferentially survive and form Tcm compared to P2RX7lo MPs. This is even more apparent when P2RX7hi and P2RX7lo early effectors are compared: approximately 100x more P2RX7hi cells form memory when compared to P2RX7lo cells, both Tcm and Trm. Our data suggest that P2RX7 in early effector CD8+ T cells promotes the generation of a common Tcm/Trm precursor.

Abstract CD4+ T cells are crucial to control pulmonary tuberculosis, but also favor uncontrolled inflammation in severe disease. Effective CD4+ T cell response to tuberculosis is related to tissue location: Lung-resident CD4+ T cells display higher effector function in comparison to circulating cells. Among the factors favoring T cell residency in non-lymphoid tissues, extracellular ATP sensing via P2RX7 is crucial for the generation of virus-specific resident memory CD8+ T cells. Yet, its role in CD4+ T cell non-lymphoid tissue residency has not been defined. Moreover, mycobacterial infection induces high extracellular ATP levels due to lung tissue damage, which is increased in response to hypervirulent strains. Here, we used P2rx7 ablation models to test the role of P2RX7 in CD4+T cell function in tuberculosis. In response to the hypervirulent Mycobacterium bovis MP287/03 strain, lung-resident WT CD4+ T cells express higher P2RX7 levels compared to circulating CD4+ T cells. Compared to WT mice, P2RX7-deficient (P2rx7−/−) mice display reduced numbers of antigen-specific (I-AbESAT-64-17) and IFN-γ-producing CD4+ T cells in the lung parenchyma. Using cell adoptive transfers, while recipient CD4-deficient mice transferred with CD4+ WT T cells are protected, mice that received CD4+P2rx7−/− T cells develop severe tuberculosis. Mechanistically, CD4+P2rx7−/− T cells have poorer accumulation and IFN-γ production in the lung parenchyma; moreover, they show reduced proliferation in situ. This defect in proliferation is exclusively observed in the lung, with no differences observed in draining lymph nodes. Together, our results show that P2RX7 promote the accumulation of protective CD4+ T cells in the lung during severe tuberculosis.