ABSTRACT
Aim To investigate the protective effect of baicalin on inflammatory response of human microvascular endothelial cells ( HMECs) induced by lipopo- lysaccharides ( LPS) and its mechanism. Methods LPS was applied to establish inflammatory model on HMECs in this work. HMECs were pretreated with different concentrations of baicalin ( 1. 0 x 10 "6 , 1. 0 x 10 ~7 and 1. 0 x 10 "8 mol • L"1) , and then exposed to LPS. The supernatant was removed and assayed for expression of the adhesion molecule ICAM-1, the inflam- atory mediator IL-6 and MCP-1 by using ELISA reagent kits. The inward flow of calcium ion was observed by fluorescence microscope, and the intracellular calcium ion level was measured by flow cytometry. The fluorescence intensity of nucleus NF-kB p65 was detected by immunoflourescent technique. The nucleus transcriptional activity of NF-kB was measured by the dual lu- ciferase reporter assay system. Moreover, the expression of protein NF-kB p65, phospo-NF-kb p65 ( p p65 ) and Toll like receptor 4 (TLR4 ) were detected by Western blot. Results The internal flow of calcium, the phosphorylation of NF-kB p65 and the transcription activity significantly increased, and the expression of ICAM-1, IL-6 and MCP-1 up-regulated after HMECs were exposed to LPS. Baicalin inhibited the inward flow of calcium ion, the nuclear translocation of NF-kB p65 and the up-regulation of transcriptional activity, decreased the expression of ICAM-1, IL-6 and MCP-1, and down-regulated the expression of NF-kB p65, p- p65 and TLR4 in a dose-dependent manner. Conclusions Baicalin possesses a protective effect on inflammatory response of endothelial cells induced by LPS, and its mechanism may be highly related to the inhibition of the internal flow of calcium and the activation of NF-kB signaling pathway, and thus reduce the level of inflammatory response.