Immune checkpoints of T cells and macrophages in an orthotopic mouse glioblastoma model
Matheus H.W. Crommentuijnᶲ*, Sjoerd T.T. Schettersᶲ, Laura J.W. Kruijssen, Yvette van Kooyk
Department of Molecular Cell Biology & Immunology, VU University Medical Center, Amsterdam
Glioblastoma (GBM) is the most common malignant primary brain tumor in adults with an extremely dismal prognosis. Tumor cells can manipulate their microenvironment to suppress anti-tumor immunity, which affects patient survival. Modulation of suppressive immune checkpoints through antibody therapy has shown promising results in several types of cancer, especially of those expressed by T cells. To study the dynamics of immune checkpoints in GBM in vivo, we set up a mouse model in which we injected murine GL26 GBM cells, transfected with ovalbumin (OVA) antigen and Firefly luciferase (Fluc), into the left striatum of immunocompetent mice. After three weeks, mice were sacrificed and spleen and brain were removed and processed for analysis of immune content. Using advanced multiplex flow cytometry and tSNE unsupervised clustering analysis of immune suppressive checkpoints and immune costimulatory markers we show highly specialized, “suppressive” T cells populations in the brain tumor microenvironment compared to the spleen of the same mouse. Moreover, tumor-infiltrating T cell populations differed significantly in their expression of key immune checkpoints from those found in non-tumor control brain and the non-tumor hemisphere of GBM brain, indicative of a GBM-induced tolerogenic microenvironment. Our aim is to use this model to investigate the brain tumor microenvironment, the dynamics of immune checkpoints and to explore new anti-tumor T cell therapies aimed to combine DC-targeted vaccines with immune checkpoint inhibition.
This project is funded by European Research Council grant: ERC-2013-AdG-339977.