Triptolide suppresses lipopolysaccharide-induced activity of toll-like receptor 4 in mouse macrophage cell line RAW 264.7

Toll-like receptor 4 (TLR4) has attracted a great deal of attention in ischemia-reperfusion injury in recent years. Triptolide has potent anti-inflammatory and immunosuppressive effects; however, the mechanism has not been fully delineated. The objective of this study was to evaluate the effects of triptolide on TLR4 expression in the mouse macrophage cell line RAW 264.7. In the first part of this study, the mouse macrophage cell line RAW 264.7 was treated with different concentrations of lipopolysaccharide (LPS) for 6 h to find the concentration of LPS to be used in the second part of this study. In the second part of the study, mouse macrophage cell line RAW 264.7 was pre-treated with triptolide at different concentrations for 1 h, and then exposed to LPS. The expression of the TLR4 and HSP70 mRNA and protein, as well as the levels of tumour necrosis factor (TNF)-alpha and interleukin (IL)-6, were assessed. In the first part of this study, the expression level of TLR4 mRNA was increased significantly in the macrophage cell line treated with LPS, and reached a plateau at 100 ng/ml. In the second part of this study, the mouse macrophage cell line RAW 264.7 pre-treated with different concentrations of triptolide, showed a dose-dependent inhibition of the levels of TLR4 mRNA and protein, TNF-alpha and IL-6. Triptolide can suppress LPS-induced TLR4 expression at both the mRNA and protein levels in the mouse macrophage cell line RAW 264.7.