Yeong-Geun Lee (Korea Basic Science Institute (KBSI))

Geum-Sook Hwang (Korea Basic Science Institute (KBSI))

Yeong-Geun Lee (Korea Basic Science Institute (KBSI))

Hoibin Jeong (Korea Basic Science Institute (KBSI))

Jueun Lee (Korea Basic Science Institute (KBSI))

Geum-Sook Hwang (Korea Basic Science Institute (KBSI))

Tumor-associated macrophages (TAMs), key immunosuppressive and pro-tumor components in the tumor microenvironment, polarize into distinct functional states depending on oxygen levels, but their underlying metabolic mechanisms have yet to be elucidated. This study aims to elucidate the oxygen-dependent metabolic and lipidomic profiles of TAMs in breast tumors and investigate their association with immune polarization.

TAMs from EO771 tumors in 4-6-week-old BALB/c-nude female mice were sorted by FACS into aerobic (Hoechst^high) and hypoxic (Hoechst^low) groups based on Hoechst33342 staining, CD11b, and F4/80 expression. Functional traits were analyzed through metabolic and lipidomic profiling, and immune gene expression was assessed by LC-QTOF-MS and qPCR, respectively.

Multivariate analyses, principal component analysis, clearly distinguished aerobic and hypoxic TAMs based on metabolomic and lipidomic profiles, reflecting oxygen-dependent metabolic heterogeneity aligned with immune polarization. Aerobic TAMs exhibited a typical M2-like polarization, with elevated expression of Arg1 and FASN, along with increased metabolites associated with arginine and fatty acid metabolism. Conversely, hypoxic TAMs showed increased Nos2 expression, indicating an M1-like phenotype.

These results show that TAMs in breast tumors exhibit distinct metabolic signatures, including changes in arginine metabolism and fatty acid synthesis, related to immune polarization under different oxygen conditions. The distinct profiles linked to M1- and M2-like polarization indicate that metabolic programming may contribute to the immunosuppressive functions of TAMs in the tumor microenvironment. These findings emphasize the metabolic flexibility of TAMs and offer insights into macrophage-targeted immunometabolic therapies.