Abstract
Backgound
Ginsenoside Rb1, the main active constituent of
Panax ginseng
, displays significant anti-inflammatory activity, although the mechanism has not been clearly unraveled. In this study, Rb1’s mechanism of anti-inflammatory effects were investigated.
Methods
The flow cytometry and enzyme-linked immunosorbent assay (ELISA) were employed to detect pro-inflammatory cytokines release. The related protein and gene expression was investigated by western blotting and qRT-PCR. The dimerization of TLR4 was measured by co-immunoprecipitation and molecular docking assays. Cellular thermal shift assay was used for the determination of the binding of Rb1 and TLR4. For animal models, LPS- or cantharidin-induced acute kidney injury, LPS-induced septic death, and dimethyl benzene-induced ear edema were employed to investigate Rb1’s anti-inflammatory activity in vivo.
Results
Rb1 significantly decreased inflammatory cytokines release in LPS-stimulated RAW264. cells and BMDMs, as well as COX-2 and iNOS amounts. Rb1 reduced LPS-associated calcium influx, ROS production, and NO generation. The NF-κB and MAPK axes participated in Rb1’s anti-inflammatory effects. Molecular docking simulation indicated Rb1 bound to TLR4 to prevent TLR4 dimerization, as confirmed by co-immunoprecipitation and cellular thermal shift assay. Furthermore, MyD88 recruitment and TAK1 expression were altered by reduced TLR4 dimerization, indicating the TLR4-MyD88-NF-κB/MAPK pathways contributed to Rb1’s anti-inflammatory process. In animal models, Rb1 markedly alleviated LPS- or cantharidin-induced acute kidney injury, rescued LPS-induced septic mice from death, and inhibited dimethyl benzene-induced mouse ear edema.
Conclusion
Overall, these findings demonstrate Rb1 exhibits marked anti-inflammatory effects, suggesting Rb1 represents an optimal molecule for treating inflammatory diseases.
Graphical abstract
Ginsenoside Rb1 significantly exhibits an anti-inflammatory effect. Rb1 decreases inflammatory cytokine release in LPS-stimulated RAW264.7 cells and BMDMs. The NF-κB and MAPK axes participate in Rb1’s anti-inflammatory effects. Molecular docking simulation indicates that Rb1 binds to TLR4 to prevent TLR4 dimerization, as confirmed by co-immunoprecipitation and cellular thermal shift assay. Furthermore, MyD88 recruitment and TAK1 expression are altered by reduced TLR4 dimerization, indicating the TLR4-MyD88-NF-κB/MAPK pathways contribute to Rb1’s anti-inflammatory process.
