Summary Monocytes and monocyte-derived macrophages (MDM) from blood circulation infiltrate and promote glioblastoma growth. Here we discover that glioma cells induce the expression of potent pro-inflammatory cytokine IL-1β in MDM, which engages IL-1R1 in glioma cells, activates NF-κB pathway, and subsequently leads to the induction of monocyte chemoattractant proteins (MCPs). Thus, a feedforward paracrine circuit of IL-1β/IL-1R1 between the tumors and MDM creates an interdependence driving glioblastoma progression. Locally antagonizing IL-1β/IL-1R1 leads to reduced MDM infiltration, diminished tumor growth, reduced exhausted CD8 + T cells, and thereby extends the survival of tumor-bearing mice. In contrast to IL-1β, IL-1a exhibits anti-tumor effects. Genetic deletion of Il1a is associated with decreased recruitment of lymphoid cells and loss of interferon (IFN) signaling in various immune populations and subsets of malignant cells. IL-1β antagonism of IL-1β should be considered as an effective anti-glioblastoma therapy. Graphical Abstract

A paracrine circuit of IL-1β/IL-1R1 between myeloid and tumor cells drives glioblastoma progression