Abstract:
M1 macrophages play a critical role in tumorigenesis and development. Insufficient infiltration of M1 macrophages can lead to inadequate CD8
+ T cell activation, impairing immune surveillance and thereby promoting immune escape. This study investigated the mechanism by which baicalin induces the polarization of RAW264.7 cells towards the M1 phenotype using an
in vitro cell model. Cell viability was assessed by the CCK-8 assay. The expression of the M1 surface marker CD86 was analyzed by flow cytometry and immunofluorescence. Cytokine tumor necrosis factor-alpha (TNF-
α) levels were measured by ELISA. Lactate levels were detected using a lactate assay kit. Western blot was used to determine the protein expression of key components of the PI3K/Akt/HIF-1
α glycolytic pathway and the key rate-limiting glycolytic enzymes lactate dehydrogenase A (LDHA) and pyruvate kinase M2 (PKM2) in RAW264.7 cells. The PI3K inhibitor LY294002 and the glycolytic inhibitor 2-DG were employed to validate the mechanism of action of baicalin. The results showed that baicalin at concentrations of 12.5-100 μmol·L
-1 had no significant effect on the viability of RAW264.7 cells. At 100 μmol·L
-1, baicalin significantly up-regulated the expression of the M1 surface marker CD86 and the cytokine TNF-
α, increased the protein expression of p-PI3K, p-Akt, HIF-1
α, LDHA, and PKM2, and elevated lactate levels. However, the up-regulatory effects of baicalin on CD86 were inhibited, and the expression of related pathway proteins was reversed, upon addition of LY294002 or 2-DG. This study reveals for the first time that baicalin drives macrophage polarization towards the M1 phenotype by activating the PI3K/Akt/HIF-1
α signaling axis and enhancing glycolytic metabolism. This finding provides new mechanistic evidence based on metabolism for its therapeutic potential in tumor immune regulation and inflammation-related diseases.