HUMAN INTESTINAL EPITHELIAL-CELLS PRODUCE PROINFLAMMATORY CYTOKINES IN RESPONSE TO INFECTION IN A SCID MOUSE-HUMAN INTESTINAL XENOGRAFT MODEL OF AMEBIASIS

The protozoan parasite Entamoeba histolytica causes amebic dysentery a nd amebic liver abscess, diseases associated with significant morbidit y and mortality worldwide. E. histolytica infection appears to involve the initial attachment. of amebic trophozoites to intestinal epitheli al cells, followed by lysis of these cells and subsequent invasion int o the submucosa, A recent in vitro study (L. Eckmann, S. L. Reed, J. R Smith, and M. F. Kagnoff, J. Clin. Invest, 96:1269-1279, 1995) demons trated that incubation of E. histolytica trophozoites with epithelial cell lines results in epithelial cell production of inflammatory cytok ines, including interleukin-1 (IL-l) and IL-8, suggesting that intesti nal epithelial cell production of cytokines might play a role in the i nflammatory response and tissue damage seen in intestinal amebiasis. T o determine whether intestinal epithelial cell production of IL-l and IL-8 occurs in response to E. histolytica infection in vivo and as an approach to studying the specific interactions between amebic trophozo ites and human intestine, we used a SCID mouse-human intestinal xenogr aft (SCID-HU-INT) model of disease, where human intestinal xenografts were infected with virulent E. histolytica trophozoites. Infection of xenografts with E. histolytica trophozoites resulted in extensive tiss ue damage, which was associated with the development of an early infla mmatory response composed primarily of neutrophils. Using oligonucleot ide primers that specifically amplify human IL-1 beta and IL-8, we cou ld demonstrate by reverse transcription PCR that mRNA for both IL-1 be ta and IL-8 is produced by human intestinal xenografts in response to amebic infection. The increase in human intestinal IL-1 beta and IL-8 in response to invasive amebiasis was confirmed by enzZ me-linked immu nosorbent assays specific for human IL-1 beta and IL-8. Using immunohi stochemistry, we confirmed that human intestinal epithelial cells were the source of IL-8 in infected xenografts and established that IL-8 p roduction can occur at sites distal to areas of intestinal mucosal dam age. These results demonstrate that human intestinal epithelial cells can produce inflammatory cytokines in response to infection in vivo an d establish the SCID-HU-INT model as a system for studying the interac tions between E. histolytica and human intestine.