Comparison of the potency of various serotypes of E. coli lipopolysaccharides in stimulating PGI2 production and suppressing ACE activity in cultured human umbilical vein endothelial cells.

We investigated the potency of various serotypes of lipopolysaccharides (LPS) by examining LPS-induced stimulation of PGI2 production and suppression of ACE activity in cultured human umbilical vein endothelial cells (HUVEC). HUVEC which had been incubated with E. coli 055:B5 and 0111:B4 for 24 h produced more prostacyclin (PGI2) in response to thrombin than HUVEC incubated with E. coli 026:B6. Also, angiotensin converting enzyme activity (ACE) in cell lysates of HUVEC incubated for 24 h with 055:B5 or 0111:B4 was suppressed significantly compared to control HUVEC or HUVEC incubated with 026:B6. From these experimental results, E. coli 055:B5 and 0111:B4 appear to be more potent than 026:B6. It is concluded that this difference in potency among various serotypes of LPS should be taken into account when experiments are designed to examine the effect of LPS on endothelial cell function.