Ergosta-7, 9 (11), 22-trien-3β-ol Interferes with LPS Docking to LBP, CD14, and TLR4/MD-2 Co-Receptors to Attenuate the NF-κB Inflammatory Pathway In Vitro and Drosophila

Abstract

Ergosta-7, 9 (11), 22-trien-3β-ol (EK100) was isolated from Cordyceps militaris, which has been used as a traditional anti-inflammatory medicine. EK100 has been reported to attenuate inflammatory diseases, but its anti-inflammatory mechanism is still unclear. We were the first to investigate the effect of EK100 on the Toll-like receptor 4 (TLR4)/nuclear factor of the κ light chain enhancer of B cells (NF-κB) signaling in the lipopolysaccharide (LPS)-stimulated RAW264.7 cells and the green fluorescent protein (GFP)-labeled NF-κB reporter gene of Drosophila. EK100 suppressed the release of the cytokine and attenuated the mRNA and protein expression of pro-inflammatory mediators. EK100 inhibited the inhibitor kappa B (IκB)/NF-κB signaling pathway. EK100 also inhibited phosphatidylinositol-3-kinase (PI3K)/Protein kinase B (Akt) signal transduction. Moreover, EK100 interfered with LPS docking to the LPS-binding protein (LBP), transferred to the cluster of differentiation 14 (CD14), and bonded to TLR4/myeloid differentiation-2 (MD-2) co-receptors. Compared with the TLR4 antagonist, resatorvid (CLI-095), and dexamethasone (Dexa), EK100 suppressed the TLR4/AKT signaling pathway. In addition, we also confirmed that EK100 attenuated the GFP-labeled NF-κB reporter gene expression in Drosophila. In summary, EK100 might alter LPS docking to LBP, CD14, and TLR4/MD-2 co-receptors, and then it suppresses the TLR4/NF-κB inflammatory pathway in LPS-stimulated RAW264.7 cells and Drosophila.