Figure 1.

Metformin, an AMPK regulator, and mevalonate modulate the fractions of MDSCs and M1/M2 macrophages. (A) THP-1 cells were treated with 0.25 to 2 mM metformin in a dose-dependent manner for 48 h., and (B) THP-1 cells were treated with 1 mM metformin, 50 μM AICAR, 20 μM Comp C and a combination of Comp C and metformin for 48 h. Next, flow cytometry analyses were performed using the markers of MDSCs (CD68⁺ CD33⁺ and CD68⁺ Arg-1⁺), and M2 macrophages (CD68⁺ CD206⁺ and CD68⁺ CD163⁺). Data are expressed as the means ± standard errors of the four different experiments; * p < 0.05, ** p < 0.005. (C) In Western blot analysis, the expressions of phosphorylated S6 and phosphorylated AMPK were analyzed after 48 h of treatment with the control vehicle or 1 mM and 2 mM metformin, 50 μM AICAR, 3 μM Comp C and 20 nM rapamycin in THP-1 cells. (D) THP-1 cells were treated with 2 mM metformin with or without 200 μM mevalonate. Next, the expression levels of MDSC (CD33⁺/CD68⁺ and Arg-1⁺/CD68⁺) and M2 macrophages (CD206⁺/CD68⁺ and CD163⁺/CD68⁺) markers were analyzed by flow cytometry. Data are expressed as means ± standard errors of the three different experiments; * p < 0.05, ** p < 0.005.