Lipopolysaccharide upregulates the expression of Toll-like receptor 4 in human vascular endothelial cells. 
To investigate the expression of Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) and the effect of lipopolysaccharide (LPS) on their expression in cultured endothelial cells.  Total RNA was extracted from ECV304 cells and isolated human umbilical vein endothelial cells (HUVECs) exposed to LPS, respectively.  The quantification of TLR2 and TLR4 mRNA in HUVECs and EVC304 cells was carried out by reverse transcriptase-polymerase chain reaction (RT-PCR).  ECV304 cells and HUVECs were able to express TLR2 and TLR4 mRNA, but the expression levels of TLR4 appeared to be stronger than those of TLR2.  LPS could upregulate the expression levels of TLR4 obviously, whereas it had no effect on the expression level of TLR2.  Our data indicate that TLR4 may be the LPS signal transducer in endothelial cells and plays important roles in the cell activation of LPS.  The ECV304 cell line is a better experimental model than isolated HUVECs in the research of endothelial cells.