This Article Full Text Full Text (PDF) Supplemental material Other Versions of this Article: IAI.01300-07v1 76/3/1115    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Stone, M. K. Articles by Obrig, T. G. Search for Related Content PubMed PubMed Citation Articles by Stone, M. K. Articles by Obrig, T. G.

 Previous Article  |  Next Article 

Infection and Immunity, March 2008, p. 1115-1121, Vol. 76, No. 3
0019-9567/08/$08.00+0     doi:10.1128/IAI.01300-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

p38 Mitogen-Activated Protein Kinase Mediates Lipopolysaccharide and Tumor Necrosis Factor Alpha Induction of Shiga Toxin 2 Sensitivity in Human Umbilical Vein Endothelial Cells ^,

Department of Medicine, Division of Nephrology, University of Virginia, Charlottesville, Virginia,¹ Department of Microbiology, University of Virginia, Charlottesville, Virginia 22908²

Received 24 September 2007/ Returned for modification 23 October 2007/ Accepted 6 December 2007

Escherichia coli O157:H7 Shiga toxin 2 (Stx2), one of the causative agents of hemolytic-uremic syndrome, is toxic to endothelial cells, including primary cultured human umbilical vein endothelial cells (HUVEC). This sensitivity of cells to Stx2 can be increased with either lipopolysaccharide (LPS) or tumor necrosis factor alpha (TNF-). The goal of the present study was to identify the intracellular signaling pathway(s) by which LPS and TNF- sensitize HUVEC to the cytotoxic effects of Stx2. To identify these pathways, specific pharmacological inhibitors and small interfering RNAs were tested with cell viability endpoints. A time course and dose response experiment for HUVEC exposure to LPS and TNF- showed that a relatively short exposure to either agonist was sufficient to sensitize the cells to Stx2 and that both agonists stimulated intracellular signaling pathways within a short time. Cell viability assays indicated that the p38 mitogen-activated protein kinase (MAPK) inhibitors SB202190 and SB203580 and the general protein synthesis inhibitor cycloheximide inhibited both the LPS and TNF- sensitization of HUVEC to Stx2, while all other inhibitors tested did not inhibit this sensitization. Additionally, SB202190 reduced the cellular globotriaosylceramide content under LPS- and TNF--induced conditions. In conclusion, our results show that LPS and TNF- induction of Stx2 sensitivity in HUVEC is mediated through a pathway that includes p38 MAPK. These results indicate that inhibition of p38 MAPK in endothelial cells may protect a host from the deleterious effects of Stx2.

Published ahead of print on 17 December 2007.

Supplemental material for this article may be found at http://iai.asm.org/.

Editor: B. A. McCormick

This article has been cited by other articles:

• Zanchi, C., Zoja, C., Morigi, M., Valsecchi, F., Liu, X. Y., Rottoli, D., Locatelli, M., Buelli, S., Pezzotta, A., Mapelli, P., Geelen, J., Remuzzi, G., Hawiger, J. (2008). Fractalkine and CX3CR1 Mediate Leukocyte Capture by Endothelium in Response to Shiga Toxin. J. Immunol. 181: 1460-1469 [Abstract] [Full Text]