Protective role of fermented mulberry leave extract in LPS-induced inflammation and autophagy of RAW264.7 macrophage cells

Abstract

Mulberry leaves have antioxidant activity and anti-inflammatory effects in several types of cells. However, the efficacy of mulberry leaves fermented with Cordyceps militaris remains unknown. Therefore, the present study aimed to investigate whether the ethanol extracts of mulberry leaves fermented with C. militaris (EMfC) can prevent lipopolysaccharide (LPS)-induced inflammation and autophagy in macrophages. To achieve this, RA W264.7 cells pretreated with three different dose of EMfCs were subsequently stimulated with LPS, and examined for alterations in the regulatory factors of inflammatory responses and key parameters of the autophagy signaling pathway. EMfC treatment inhibited the generation of reactive oxidative species; however, significant activity was observed for 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging (IC50=579.6703 mg/ml). Most regulatory factors in inflammatory responses were significantly inhibited following treatment with EMfC, without any significant cellular toxicity. EMfC-treated groups exhibited marked suppression of nitrogen oxide (NO ) levels, mRNA expression levels of iNO S/CO X-2, levels of all inflammatory cytokines (TNF-α, IL- 1β and IL- 6) and phosphorylation of MAPK members, as well as recovery of cell cycle progression. Furthermore, similar effects were observed in the LPS-induced autophagy signaling pathway of RA W264.7 cells. The expression levels of microtubule-associated protein 1A/1B-light chain 3 (LC 3) and Beclin exhibited a dose-dependent decrease in the EMfC-treated groups compared with in the Vehicle-treated group, whereas the phosphorylation of PI3K and mTOR were enhanced in a dose-dependent manner in the same groups. Overall, the results of the present study provide evidence that exposure to EMfC protects against LPS-induced inflammation and autophagy in RA W264.7 cells. These results indicated that EMfC is a potential candidate for treatment of inflammatory diseases.