Modulating Glutamine Metabolism Reprograms Pro-Inflammatory Differentiation in Macrophages.

Area of Science:

• Immunology
• Cancer Biology
• Metabolic Pathways

Background:

• Glutamine analog drugs, like DON, have shown potential in reprogramming macrophages in vivo.
• Understanding the direct versus indirect effects of DON on macrophage polarization is crucial for therapeutic development.

Purpose of the Study:

• To investigate the direct impact of DON on M1 macrophage polarization in vitro.
• To elucidate the stage-specific mechanisms of glutamine inhibition in modulating macrophage phenotypes.

Main Methods:

• Utilized a murine bone marrow-derived macrophage (BMDM) model for in vitro studies.
• Applied DON during M1 differentiation and to fully polarized M1 macrophages.
• Performed multi-omics analyses (bulk RNA-seq, LC-MS), time-course assays, and glutamine depletion experiments.

Main Results:

• DON initially suppressed M1 activity but led to sustained pro-inflammatory activation.
• Prolonged glutamine inhibition resulted in elevated glutamine levels, sustaining pro-inflammatory gene transcription.
• M2 and tumor-associated macrophages (TAMs) were more susceptible to DON, leading to functional suppression.

Conclusions:

• Glutamine inhibition exhibits stage-specific effects on M1 macrophage polarization.
• DON can sustain pro-inflammatory, anti-tumor macrophage activity while suppressing immunosuppressive myeloid subsets in cancer.
• Findings provide a mechanistic rationale for DON-based cancer immunotherapies.