Salvianolic acid B inhibits RAW264.7 cell polarization towards M1 type by inhibiting NF-κB and Akt/mTOR pathways

Abstract M1 macrophages can secrete a large number of pro-inflammatory factor and promote the expansion of atherosclerosis plaque and process. Salvianolic acid B (Sal B) has anti-inflammatory, anti-tumor and other effects, but there is no study on whether Sal B can regulate the polarization of macrophages to exert anti-atherosclerosis effect. Therefore, the present study is investigating the inhibition of Sal B in the process of M1 macrophages polarization and its underlying mechanism. The effects of different treatments on cell viability, expression and secretion of related proteins, phenotypic markers and cytokines were detected by MTT, Western blot assay, RT-qPCR and ELISA. The cell viability was no significantly change when the concentration of Sal B is under 200 µM, and LPS (100 ng/mL) + IFN-γ (2.5 ng/mL) successfully induced M1 polarization. RT-qPCR and ELISA results indicated that Sal B can down-regulate the M1 markers (iNOS, TNF-α, and IL-6), and upregulate the M2 markers (Arg-1 and IL-10). Western blot was used to detect the expression of NF-κB, p-Akt, p-mTOR, LC3-II, Beclin-1, and p62, which suggested that Sal B inhibits RAW264.7 macrophages to M1 polarization by promoting autophagy in nuclear factor-κB (NF-κB) signaling pathway. The present study indicated that Sal B inhibits macrophages to M1 polarization by inhibiting the NF-κB signaling pathway and down-regulating Akt/mTOR to promote autophagy.