Omics and Transgenic Analyses Reveal that Salvianolic Acid B Exhibits its Anti-Inflammatory Effects through Inhibiting the Mincle-Syk-Related Pathway in Macrophages

Salvianolic acid B (Sal B), the main water-soluble compound in Salvia miltiorrhiza, is known to exhibit anti-inflammatory activity, however, the underlying mechanism(s) is not completely uncovered. In this study, Sal B inhibited lipopolysaccharide (LPS)-induced M1 activation and promoted the transformation of macrophages from M1- to M2-type polarization. The altered lipid profiles of LPS-induced RAW 264.7 macrophages were partly restored by Sal B treatment. At the proteomic level, a total of 5612 proteins were identified and 432 were significantly changed in macrophages under LPS treatment. The differential proteins were classified into four clusters according to their expression level in blank, LPS, and Sal B groups. LPS-induced proteins in Cluster IV including Kif14, Mincle, and Sec62 were significantly recovered to almost normal levels by Sal B treatment. Use of knockdown Mincle or picetannol (inhibitor of Syk) led to significant reductions in the gene expressions of IL-1β, iNOS, and IL-12 and the release of NO. The converse was, however, observed for overexpressed Mincle. In addition, LPS- or trehalose-6,6-dibehenate-induced phosphorylation of Syk and PKCδ was decreased by Sal B treatment. These results suggest that Sal B inhibition of LPS-induced inflammation might be through inhibition of the Mincle-Syk-PKCδ signaling pathway.