Icariin induces the Expression of Toll-like Receptor 9 in Ana-1 Murine Macrophages

Icariin is the major pharmacologically active compound of Herba epimedii which has been used as a tonic, aphrodisiac and an antirheumatic in traditional Chinese medicine. This study analysed the effect of icariin on the expression of Toll-like receptor 9 (TLR9) which plays an important role in regulation of the innate immune response. Stimulation of Ana-1 murine macrophages with icariin induced a significant dose-dependent expression of TLR9, and its mRNA expression which increased from 3 h post-treatment was approximately fivefold that of DMSO-treated cells. Several molecules, such as myeloid differentiation factor 88, tumor necrosis factor-alpha and interleukin 6, which are involved in the TLR9 downstream signaling pathway, were also significantly up-regulated in response to icariin stimulation. Our findings demonstrated that icariin is able to induce the expression of TLR9. Copyright (C) 2011 John Wiley & Sons, Ltd.