Paeonol inhibits TNF-α-induced GM-CSF expression in fibroblast-like synoviocytes

Objectives: Granulocyte macrophage colony-stimulating factor (GM-CSF) has been proved to be among the most important chemokines, playing a key role in rheumatoid arthritis (RA). However, the mechanism underlying the regulation of GM-CSF has not been established clearly yet. The aim of this study was to investigate the influence of paeonol in the expression of GM-CSF in fibroblast-like synoviocytes (FLS). Methods: The expression of GM-CSF was detected both at protein and mRNA levels in FLS after the stimulation of TNF-alpha at diverse concentrations and times. And then GM-CSF was detected again after pre-treatment with paeonol. Phosphorylation of PI3K/Akt and expression of NF-kappa B and p-I kappa B alpha were detected with western blot. Meanwhile, inhibitors of the pathways were used to investigate the mechanism of regulation of GM-CSF. Results: Recombinant TNF-alpha up-regulated GM-CSF in a concentration- and time-dependent manner in FLS, which was significantly suppressed by paeonol. Paeonol also exerted its ability to suppress the promoting effects of TNF-alpha on the phosphorylation of PI3K/Akt and activation of NF-kappa B pathway. Administration of the inhibitors LY294002, perifosine, BAY11-7082, and SC-514 confirmed the roles of PI3K/Akt and NF-kappa B on the production of GM-CSF. Furthermore, TNF-alpha induced proliferation, while paeonol suppressed proliferation of FLS. Conclusion: These results demonstrate that paeonol suppressed TNF-alpha-induced GM-CSF production via the PI3K/Akt/NF-kappa B pathway.