TLR3 recognizes viral dsRNA and its synthetic mimetic polyinosinic-polycytidylic acid (poly(I:C)). TLR3 expression is commonly considered to be restricted to dendritic cells, NK cells, and fibroblasts. In this study we report that human γδ and αβ T lymphocytes also express TLR3, as shown by quantitative real-time PCR, flow cytometry, and confocal microscopy. Although T cells did not respond directly to poly(I:C), we observed a dramatic increase in IFN-γ secretion and an up-regulation of CD69 when freshly isolated γδ T cells were stimulated via TCR in the presence of poly(I:C) without APC. IFN-γ secretion was partially inhibited by anti-TLR3 Abs. In contrast, poly(I:C) did not costimulate IFN-γ secretion by αβ T cells. These results indicate that TLR3 signaling is differentially regulated in TCR-stimulated γδ and αβ T cells, suggesting an early activation of γδ T cells in antiviral immunity.
Immune evasion is indispensable for cancer initiation and progression, although its underlying mechanisms in pancreatic ductal adenocarcinoma (PDAC) are not fully known. Here, we characterize the function of tumor-derived PGRN in promoting immune evasion in primary PDAC. Tumor- but not macrophage-derived PGRN is associated with poor overall survival in PDAC. Multiplex immunohistochemistry shows low MHC class I (MHCI) expression and lack of CD8+ T cell infiltration in PGRN-high tumors. Inhibition of PGRN abrogates autophagy-dependent MHCI degradation and restores MHCI expression on PDAC cells. Antibody-based blockade of PGRN in a PDAC mouse model remarkably decelerates tumor initiation and progression. Notably, tumors expressing LCMV-gp33 as a model antigen are sensitized to gp33-TCR transgenic T cell-mediated cytotoxicity upon PGRN blockade. Overall, our study shows a crucial function of tumor-derived PGRN in regulating immunogenicity of primary PDAC.
Immune evasion is indispensable for cancer initiation and progression, although its underlying mechanisms in pancreatic ductal adenocarcinoma (PDAC) remain elusive. Here, we unveiled a cancer cell-autonomous function of PGRN in driving immune evasion in primary PDAC. Tumor- but not macrophage-derived PGRN was associated with poor overall survival in PDAC. Multiplex immunohistochemistry revealed low MHC class I (MHCI) expression and lack of CD8+ T cells infiltration in PGRN-high tumors. Inhibition of PGRN abrogated autophagy-dependent MHCI degradation and restored MHCI expression on PDAC cells. Antibody-based blockade of PGRN in a genetic PDAC mouse model remarkably decelerated tumor initiation and progression. Notably, tumors expressing LCMV-gp33 as model antigen were sensitized towards cytotoxic gp33-TCR transgenic T cells upon anti-PGRN antibody treatment. Overall, our study uncovered an unprecedented role of tumor-derived PGRN in regulating immunogenicity of primary PDAC.
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