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Updated: May 28, 2026
Depletion and Reconstitution of Macrophages in Mice
Published on: August 1, 2012
Effect of PI3K-p110α Inhibitor Alpelisib in the Differentiation and Effector Functions of M-CSF and GM-CSF
Cristina Villa-Gómez1, Verónica Bermejo1, Inmaculada Márquez-Leiva1
1Immunology Department, National Centre for Microbiology (CNM), Carlos III Health Institute (ISCIII), 28220 Madrid, Spain.
Abstract:
Phosphatidylinositol-3-kinases (PI3Ks) are heterodimers of catalytic and regulatory subunits that regulate cell metabolism, activation, and survival. PI3K, particularly the p110α catalytic isoform, is frequently mutated in cancer, and highly specific inhibitors such as alpelisib are currently used in oncology and in PIK3CA-related overgrowth disorders. Given the relevance of macrophages in anti-tumor immunity, we examined the impact of alpelisib on murine monocytes' intracellular signaling and on in vitro differentiation, polarization, and effector functions of macrophages. Real-time qPCR (RT-qPCR) showed comparable relative expression of PI3K isoforms (p110α, p110β, p110δ, p110γ and p85) in bone marrow monocytes and in macrophages differentiated with macrophage colony-stimulating factor (M-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF). However, alpelisib increased p110α, p110β, and p85 relative gene expression (2-3-fold) during M-CSF-dependent differentiation. Functionally, alpelisib-treated M-CSF macrophages displayed enhanced interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α) secretion and reduced IL-10 production after lipopolysaccharide (LPS) plus interferon gamma (IFN-γ) or LPS stimulation. In contrast, GM-CSF macrophages differentiated with alpelisib secreted lower levels of IL-6 and TNF-α and reduced inducible nitric oxide synthase (iNOS) and arginase-1 (Arg-1) gene expression. Additionally, cytokine profiles (IL-2, IL-6, IFN-γ and IL-10) were altered when alpelisib-treated macrophages were cocultured with CD4+ T cells under either antigen-specific or polyclonal activation conditions, indicating that the inhibitor modifies both differentiation and subsequent effector interactions of the macrophages. Thus, alpelisib induces lasting effects on macrophage differentiation and function, with potential implications in tumor-associated macrophages that develop under M-CSF or GM-CSF-rich cancer microenvironments.
Insights
Alpelisib, a PI3K inhibitor, alters macrophage differentiation and function. It enhances M-CSF macrophage inflammatory responses but impairs GM-CSF macrophage anti-tumor immunity, impacting cancer microenvironments.
Area of Science:
- Immunology
- Molecular Biology
- Oncology
Background:
- Phosphatidylinositol-3-kinases (PI3Ks) are crucial for cell signaling, metabolism, and survival.
- The PI3K pathway, particularly the p110α isoform, is a common target in cancer therapy, with alpelisib being a specific inhibitor.
- Macrophages play a significant role in anti-tumor immunity and are influenced by cytokines like M-CSF and GM-CSF in the tumor microenvironment.
Purpose of the Study:
- To investigate the effects of alpelisib on murine monocyte-derived macrophage differentiation, polarization, and effector functions.
- To assess how alpelisib influences intracellular signaling pathways in macrophages.
- To understand the implications of alpelisib's impact on macrophages within cancer settings.
Main Methods:
- Real-time quantitative PCR (RT-qPCR) to analyze PI3K isoform gene expression.
- In vitro differentiation of bone marrow monocytes using M-CSF and GM-CSF.
- Stimulation of macrophages with lipopolysaccharide (LPS) and interferon gamma (IFN-γ) to assess cytokine secretion and gene expression (IL-6, TNF-α, IL-10, iNOS, Arg-1).
- Co-culture experiments with CD4+ T cells to evaluate altered cytokine profiles.
Main Results:
- Alpelisib treatment increased PI3K isoforms (p110α, p110β, p85) gene expression during M-CSF-dependent differentiation.
- M-CSF-derived macrophages treated with alpelisib showed enhanced IL-6 and TNF-α secretion and reduced IL-10 production.
- GM-CSF-derived macrophages treated with alpelisib exhibited decreased IL-6, TNF-α, iNOS, and Arg-1 expression.
- Alpelisib altered cytokine profiles in macrophage-T cell co-cultures, affecting T cell activation.
Conclusions:
- Alpelisib significantly impacts macrophage differentiation and function in a context-dependent manner (M-CSF vs. GM-CSF).
- The drug induces lasting functional changes in macrophages, potentially modulating anti-tumor immunity.
- These findings suggest that alpelisib's effects on tumor-associated macrophages could have significant implications in cancer therapy.
