Synergy of LPS and Shiga-toxin exposure on the RNA expression program of cultured human umbilical vein endothelial cells.

BackgroundHemolytic uremic syndrome (HUS) is a primary thrombotic microangiopathy that can cause acute renal failure, particularly in children, and is commonly triggered by Shiga toxin-producing Escherichia coli (STEC) infection. Although previous in vitro studies have shown that Shiga toxin (STX) can directly affect the endothelium, gram-negative bacteria such as E. coli also contain lipopolysaccharide (LPS) which is known to independently activate endothelial cells. Furthermore, studies in mice and baboons have shown a synergistic effect of LPS and STX in inducing HUS when administered simultaneously. ObjectiveDetermine how LPS, STX, or combined LPS/STX treatment affect the gene expression program of endothelial cells. MethodsHuman umbilical vein endothelial cells (HUVECs) were treated with STX, LPS or a combination of STX and LPS for either 4 or 24 hours, after which unbiased RNA sequencing analysis was performed. ResultsFour-hour treatment with LPS resulted in a greater number of differentially expressed genes as compared to treatment with STX. In contrast, 24-hour treatment with LPS or STX induced similar numbers of differentially expressed genes. Dual treatment with both toxins resulted in a synergistic effect, showing significant up-or downregulation of multiple transcripts that were not observed in either single treatment group, particularly at the 24-hour timepoint. ConclusionOur data provide a resource for assessing the role of endothelial cell gene expression in the pathogenesis of STEC infection and suggest that the responses of these cells to LPS, STX, or combined LPS/STX treatment are unique and temporally regulated.