Related Experiment Video
Updated: Oct 12, 2025
Studying the Effects of Tumor-Secreted Paracrine Ligands on Macrophage Activation using Co-Culture with Permeable Membrane Supports
Published on: November 28, 2019
Macrophage-Targeted Therapy Unlocks Antitumoral Cross-talk between IFNγ-Secreting Lymphocytes and IL12-Producing
Christina Pfirschke1, Rapolas Zilionis2,3, Camilla Engblom1
1Center for Systems Biology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, Massachusetts.
Abstract:
Macrophages often abound within tumors, express colony-stimulating factor 1 receptor (CSF1R), and are linked to adverse patient survival. Drugs blocking CSF1R signaling have been used to suppress tumor-promoting macrophage responses; however, their mechanisms of action remain incompletely understood. Here, we assessed the lung tumor immune microenvironment in mice treated with BLZ945, a prototypical small-molecule CSF1R inhibitor, using single-cell RNA sequencing and mechanistic validation approaches. We showed that tumor control was not caused by CSF1R+ cell depletion; instead, CSF1R targeting reshaped the CSF1R+ cell landscape, which unlocked cross-talk between antitumoral CSF1R- cells. These cells included IFNγ-producing natural killer and T cells, and an IL12-producing dendritic cell subset, denoted as DC3, which were all necessary for CSF1R inhibitor-mediated lung tumor control. These data indicate that CSF1R targeting can activate a cardinal cross-talk between cells that are not macrophages and that are essential to mediate the effects of T cell-targeted immunotherapies and promote antitumor immunity.See related Spotlight by Burrello and de Visser, p. 4.
Insights
Colony-stimulating factor 1 receptor (CSF1R) inhibitors control tumors not by depleting macrophages, but by enabling communication between other immune cells, including natural killer cells, T cells, and dendritic cells, to promote antitumor immunity.
Area of Science:
- Immunology
- Cancer Biology
- Pharmacology
Background:
- Macrophages expressing colony-stimulating factor 1 receptor (CSF1R) are prevalent in tumors and associated with poor patient outcomes.
- CSF1R-targeting drugs aim to suppress pro-tumorigenic macrophage functions, but their precise mechanisms are not fully understood.
Purpose of the Study:
- To investigate the impact of CSF1R inhibition on the lung tumor immune microenvironment.
- To elucidate the mechanisms by which CSF1R inhibitors mediate tumor control.
Main Methods:
- Single-cell RNA sequencing was employed to analyze the murine lung tumor immune microenvironment after treatment with the CSF1R inhibitor BLZ945.
- Mechanistic validation approaches were used to confirm observed cellular interactions and functions.
Main Results:
- Tumor control was not achieved through the depletion of CSF1R-expressing cells.
- CSF1R inhibition reshaped the tumor immune landscape, fostering cross-talk between antitumoral CSF1R-negative cells.
- Key effector cells included IFNγ-producing natural killer and T cells, and IL12-producing dendritic cell subset 3 (DC3).
Conclusions:
- CSF1R targeting activates crucial cross-talk between non-macrophage immune cells, rather than solely targeting macrophages.
- This activated cellular communication is essential for mediating the effects of T cell-targeted immunotherapies.
- The findings highlight a novel mechanism for promoting antitumor immunity through CSF1R inhibition.
Related Concept Videos
01:27Tumor Immunotherapy
01:28Cells of the Innate Immune Response
Phagocytes
Phagocytes police the peripheral tissues by removing cellular debris and responding to the invasion of foreign substances or pathogens. Many phagocytes attack and remove microorganisms even before lymphocytes detect them. The human body has two general...
01:27Cytotoxic T Cells-mediated Immune Response
Immunological surveillance is the ability of immune cells to monitor and eliminate infected cells with intracellular pathogens, neoplastically transformed cells, and cells with non-self antigens. Cytotoxic T cells and NK...
01:40Cell-mediated Immune Responses