GM-CSF promotes the immunosuppressive activity of glioma-infiltrating myeloid cells through interleukin-4 receptor-?.
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ABSTRACT: Malignant gliomas are lethal cancers in the brain and heavily infiltrated by myeloid cells. Interleukin-4 receptor-? (IL-4R?) mediates the immunosuppressive functions of myeloid cells, and polymorphisms in the IL-4R? gene are associated with altered glioma risk and prognosis. In this study, we sought to evaluate a hypothesized causal role for IL-4R? and myeloid suppressor cells in glioma development. In both mouse de novo gliomas and human glioblastoma cases, IL-4R? was upregulated on glioma-infiltrating myeloid cells but not in the periphery or in normal brain. Mice genetically deficient for IL-4R? exhibited a slower growth of glioma associated with reduced production in the glioma microenvironment of arginase, a marker of myeloid suppressor cells, which is critical for their T-cell inhibitory function. Supporting this result, investigations using bone marrow-derived myeloid cells showed that IL-4R? mediates IL-13-induced production of arginase. Furthermore, glioma-derived myeloid cells suppressed T-cell proliferation in an IL-4R?-dependent manner, consistent with their identification as myeloid-derived suppressor cells (MDSC). Granulocyte macrophage colony-stimulating factor (GM-CSF) plays a central role for the induction of IL-4R? expression on myeloid cells, and we found that GM-CSF is upregulated in both human and mouse glioma microenvironments compared with normal brain or peripheral blood samples. Together, our findings establish a GM-CSF-induced mechanism of immunosuppression in the glioma microenvironment via upregulation of IL-4R? on MDSCs.
SUBMITTER: Kohanbash G
PROVIDER: S-EPMC3829000 | biostudies-literature | 2013 Nov
REPOSITORIES: biostudies-literature
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