OBJECTIVETo test whether tanshinone II A (Tan II A), a highly valued herb derivative to treat vascular diseases in Chinese medicine, could protect endothelial cells from bacterial endotoxin (lipopolysaccharides, LPS)-induced endothelial injury.

METHODSEndothelial cell injury was induced by treating human umbilical vein endothelial cells (HUVECs) with 0.2 μg/mL LPS for 24 h. Y27632 and valsartan were used as positive controls. The effects of tanshinone II A on the LPS-induced cell viability and apoptosis rate of HUVECs were tested by flow cytometry, cell migration by transwell, adhesion by a 96-well plate pre-coated with vitronectin and cytoskeleton reorganization by immunofluorescence assay. Rho/Rho kinase (ROCK) pathway-associated gene and protein expression were examined by microarray assay; quantitative real-time polymerase chain reaction and Western blotting were used to confirm the changes observed by microarray.

RESULTSTan II A improved cell viability, suppressed apoptosis and protected cells from LPS-induced reductions in cell migration and adhesion at a comparable magnitude to that of Y27632 and valsartan. Tan II A, Y27632 and valsartan also normalized LPS-induced actomyosin contraction and vinculin protein aggregation. A microarray assay revealed increased levels of fibronectin, integrin A5 (ITG A5), Ras homolog gene family member A (RhoA), myosin light chain phosphatase, phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K, or PIP2 in Western blotting), focal adhesion kinase, vascular endothelial growth factor and vascular endothelial growth factor receptor 2 in the damaged HUVECs, which were attenuated to different degrees by Tan II A, Y27632 and valsartan.

CONCLUSIONTan II A exerted a strong protective effect on HUVECs, and the mechanism was caused, at least in part, by a blockade in the Rho/ROCK pathway, presumably through the down-regulation of ITG A5.