Previous in vivo studies demonstrated that JHU083/6-Diazo-5-oxo-L-norleucine (DON), a glutamine analog drug, potently reprograms M1/M2 macrophages. To determine whether these effects are direct or indirect, we utilized an in vitro murine bone marrow-derived macrophage model, which recapitulates macrophage differentiation and polarization processes, to examine the impact of DON on the M1 macrophages. DON was applied during M1 differentiation or to fully polarized M1 macrophages, revealing that glutamine inhibition initially suppressed M1 activity but later enhanced it, resulting in sustained pro-inflammatory activation. Multi-omics analyses (bulk RNA-sequencing and LC-MS), time-course assays, and glutamine depletion experiments consistently suggested that prolonged glutamine inhibition elevated glutamine levels, which sustained pro-inflammatory gene transcription. In contrast, M2 and tumor-associated macrophages, which are immunosuppressive, were more susceptible to DON, leading to functional suppression. Collectively, our findings uncover stage-specific mechanisms by which glutamine inhibition modulates M1 polarization, offering a mechanistic rationale for therapeutic strategies that sustain pro-inflammatory, anti-tumor macrophage activity while concurrently suppressing immunosuppressive myeloid subsets in cancer.
Qi et al. (Sun,) studied this question.