A topographic approach to the markers of macrophage/microglia and other cell types in high grade glioma

In glioblastoma, glioma-associated microglia/macrophages (GAMs) represent the major population of tumor infiltrating cells, with up to one half of the cells of the tumor mass. Recent studies have shown that microglia are involved in the maintenance of immunological homeostasis and protection against autoimmunity. However, despite the growing body of evidence on the topic, many aspects are yet to be clarified. In our study, 3 different situations emerged concerning the markers of microglial/macrophage-related and other cell types in GBM patients: i) most of the markers (IBA1, TMEM119, CD206 and CD86) show an ascending gradient from the tumor center to the non-tumor/healthy area of the brain; ii) one marker (CD204) shows a descending gradient, going from the center of the tumor to the non-tumor/healthy brain area; iii) two markers (CD163 and P2RY12) show no gradient. These observations support the idea that the magnitude of the diverted inflammation is a ‘extensive’ rather than a ‘local’ phenomenon and that could possibly play a role in disease resistance and relapse.