Schisandrin B restores M1/M2 balance through miR-124 in lipopolysaccharide-induced BV2 cells.

Background: In this study, Schisandrin B (SCHB), the main active component of Schisandra chinensis extract (SCE), was taken as the research object. From gene, microRNA (miR-124), and the level of protein expression system to study the influences of microglia phenotype to play the role of nerve inflammation.

Methods: In this study, we investigated the role of miR-124 in regulating microglial polarization alteration and NF-κB/TLR4 signaling and MAPK signaling in the LPS-induced BV2 by PCR, western blot, ELISA, immunofluorescence, and cytometry.

Results: SCE and SCHB significantly reduced the NO-releasing, decreased the levels of TNF-α, iNOS, IBA-1, and ratio of CD86+/CD206+, and increased the levels of IL-10, Arg-1. In addition, SCE and SCHB inhibited the nucleus translocation of NF-κB, decreased the expressions of IKK-α, and increased the expressions of IκB-α. Besides, the expressions of TLR4 and MyD88, and the ratios of p-p38/p38, p-ERK/ERK, and p-JNK/JNK were reduced by SCE and SCHB treatments. Furthermore, SCHB upregulated the mRNA levels of miR-124. However, the effects of SCHB were reversed by the miR-124 inhibitor.

Conclusions: These findings suggested SCHB downregulated NF-κB/TLR4/MyD88 signaling pathway and MAPK signaling pathway via miR-124 to restore M1/M2 balance and alleviate depressive symptoms.