Curcumin induces M1 phenotype derived from murine RAW264.7 macrophages polarization to alternatively activated M2 phenotype

Objective: To observe the effect of curcumin on RAW264.7 macrophages induced with LPS and IFNγ (M1) and the mechanisms involved. Methods: Curcumin of different concentrations (6.25 μmol/L, 12.5 μmol/L and 25 μmol/L) was used to treat RAW264.7 macrophages induced with LPS and IFNγ (M1) for 12 h, and RAW264.7 macrophages induced with LPS and IFNγ (M1) were incubated with 20 μmol/L GW9662 and 25 μmol/L curcumin for 12 h. Using Real-time PCR, ELISA and Western blotting analysis, we examined the expressions of IL-1β, IL-6, PPARγ and phenotype markers M2 (KLF4, FIZZ1, and MGL1) and the expressions of KLF4 and FIZZ1 when PPARγ was inhibited. Results: Curcumin of different concentrations all could inhibit the expressions of IL-1β and IL-6 in RAW264.7 macrophages induced with LPS and IFNγ (M1). Curcumin of different concentrations could upregulate the expression of M2 markers (KLF4, FIZZ1 and MGL1) and PPARγ in RAW264.7 macrophages induced with LPS and IFNγ (M1). When M1 macrophages were incubated with curcumin and GW9662, the expression of the M2 phenotype markers was reduced. Conclusion: Curcumin polarized the M1 phenotype macrophages derived from RAW264.7 macrophages to become M2 phenotype through activating PPARγ.