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Infection and Immunity, November 2008, p. 5158-5163, Vol. 76, No. 11
0019-9567/08/$08.00+0     doi:10.1128/IAI.00645-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Prostaglandin E2 Produced by Entamoeba histolytica Binds to EP4 Receptors and Stimulates Interleukin-8 Production in Human Colonic Cells{triangledown}

Indranil Dey and Kris Chadee*

Department of Microbiology and Infectious Diseases, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1

Received 26 May 2008/ Returned for modification 7 July 2008/ Accepted 12 August 2008

Entamoeba histolytica pathogenesis in the colon occurs in a stepwise fashion. It begins with colonization of the mucin layer, which is followed by stimulation of a proinflammatory response that causes nonspecific tissue damage that may facilitate parasite invasion of the underlying colonic mucosa. Unfortunately, the parasite and/or host factors that stimulate a proinflammatory response in the gut are poorly understood. In this study, we found that live E. histolytica or secretory or proteins (SP) and soluble ameba components (SAP) can markedly increase interleukin-8 (IL-8) mRNA expression and protein production in colonic epithelial cells. The IL-8-stimulating molecule produced by live amebae was identified as prostaglandin E2 (PGE2) as trophozoites treated with cyclooxygenase inhibitors inhibited the biosynthesis of PGE2 and eliminated IL-8 production induced by live parasites or ameba components. Moreover, using specific prostaglandin EP2 and EP4 receptor agonists and antagonists, we found that PGE2 binds exclusively through EP4 receptors in colonic epithelial cells to stimulate IL-8 production. Silencing of EP4 receptors with EP4 small interfering RNA completely eliminated SP- and SAP-induced IL-8 production. These studies identified bioactive PGE2 as a one of the major virulence factors produced by E. histolytica that can stimulate the potent neutrophil chemokine and activator IL-8, which can trigger an acute host inflammatory response. Thus, the induction of IL-8 production in response to E. histolytica-derived PGE2 may be a mechanism that explains the initiation and amplification of acute inflammation associated with intestinal amebiasis.

* Corresponding author. Mailing address: Department of Microbiology and Infectious Diseases, University of Calgary, 3330 Hospital, NW Drive, Calgary, Alberta, Canada T2N 4N1. Phone: (403) 210-3975. Fax: (403) 270-2772. E-mail: kchadee{at}ucalgary.ca

{triangledown} Published ahead of print on 18 August 2008.

Editor: W. A. Petri, Jr.

Infection and Immunity, November 2008, p. 5158-5163, Vol. 76, No. 11
0019-9567/08/$08.00+0     doi:10.1128/IAI.00645-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.





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