Abstract:  Objective · To investigate the role and mechanism of CaMKKβ in RAW264.7 macrophage M2 polarization induced by interleukin-4 (IL-4). 
 Methods · IL-4 induced RAW264.7 polarization was measured by RT-PCR and ELISA. Western blotting was used to analyze the total and phosphorylated protein levels of CaMKKβ, AMPK, JAK2 and STAT3 during polarization. A lentiviral vector carrying an shRNA targeting the CaMKKβ gene was successfully constructed. The expression of M1 and M2 markers and the expression of phosphorylated AMPK, JAK2, STAT3 were detected by RTPCR and Western blotting respectively. The protein activity of AMPK, JAK2 and STAT3 were selectively blocked, and then the effect of IL-4 on macrophage polarization was detected by RT-PCR.  Results · IL-4 significantly polarized RAW264.7 cells towards M2 macrophages (P<0.05), and the phosphorylated protein expression of CaMKKβ, AMPK, JAK2, STAT3 was significantly increased (all P<0.05). The expression of M2 markers induced by IL-4 was decreased and the phosphorylation of AMPK, JAK2 and STAT3 was also decreased after knockdown of CaMKKβ by shRNA (all P<0.05). The polarization of macrophages to M2 was decreased after the activities of AMPK, JAK2 and STAT3 proteins were blocked respectively (all P<0.05).  Conclusion · CaMKKβ promotes IL-4 induced M2 macrophage polarization via activation of AMPK/JAK2/STAT3 pathway.

Key words:  CaMKKβ, AMPK, JAK2, STAT3, macrophage polarization