The Evolving Landscape of Monocyte/Macrophage System in Glioma

Glioma is one of the most common types of primary brain tumors in adults, highly malignant and resistant to conventional treatments. Glioma-associated macrophages (GAMs) represent the major immune cell populations present in the tumor microenvironment and consist of both brain-resident microglia and monocyte-derived macrophages. Clinical studies and experimental mouse models show that tumor-reprogrammed GAMs adopt a unique phenotype of activation to support glioma growth, which in turn provides attractive targets for the develop- ment of promising immunotherapeutic strategies. Recent advances in single cell analysis techniques have allowed a definition of the heterogeneity of macrophage populations in the tissue in terms of localization and functions, overcoming the stunting issue about nomenclature and standardization of macrophage activation states.