Human intestinal epithelial cells produce proinflammatory cytokines in response to infection in a SCID mouse-human intestinal xenograft model of amebiasis

Abstract

The protozoan parasite Entamoeba histolytica causes amebic dysentery and amebic liver abscess, diseases associated with significant morbidity and mortality worldwide. E. histolytica infection appears to involve the initial attachment of amebic trophozoites to intestinal epithelial cells, followed by lysis of these cells and subsequent invasion into 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) demonstrated that incubation of E. histolytica trophozoites with epithelial cell lines results in epithelial cell production of inflammatory cytokines, including interleukin-1 (IL-1) and IL-8, suggesting that intestinal epithelial cell production of cytokines might play a role in the inflammatory response and tissue damage seen in intestinal amebiasis. To determine whether intestinal epithelial cell production of IL-1 and IL-8 occurs in response to E. histolytica infection in vivo and as an approach to studying the specific interactions between amebic trophozoites and human intestine, we used a SCID mouse-human intestinal xenograft (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 tissue damage, which was associated with the development of an early inflammatory response composed primarily of neutrophils. Using oligonucleotide primers that specifically amplify human IL-1␤ and IL-8, we could demonstrate by reverse transcription PCR that mRNA for both IL-1␤ and IL-8 is produced by human intestinal xenografts in response to amebic infection. The increase in human intestinal IL-1␤ and IL-8 in response to invasive amebiasis was confirmed by enzyme-linked immunosorbent assays specific for human IL-1␤ and IL-8. Using immunohistochemistry, we confirmed that human intestinal epithelial cells were the source of IL-8 in infected xenografts and established that IL-8 production can occur at sites distal to areas of intestinal mucosal damage. These results demonstrate that human intestinal epithelial cells can produce inflammatory cytokines in response to infection in vivo and establish the SCID-HU-INT model as a system for studying the interactions between E. histolytica and human intestine.

Expression of Epstein–Barr virus‐induced gene 3 and other interleukin‐12‐related molecules by human intestinal epithelium

“…Human intestinal xenografts were generated as described before. 6,[32][33][34][35][36] Briefly, human fetal intestine, gestational age 16-20 weeks (Advanced Biosciences Resources, Alameda, CA) was transplanted subcutaneously onto the backs of C57BL ⁄6 SCID mice. Intestinal xenografts were allowed to mature for at least 10 weeks after transplantation, at which time the epithelium, which is strictly of human origin, is fully differentiated.…”

Expression of immune modulator cytokines in human fulminant amoebic colitis

“…Our current results support the hypothesis that the production of cytokines, such as IL-1 and IL-8, by intestinal epithelial cells could play a central role in the pathogenesis of amoebic infection. It is likely that this occurs by attracting neutrophils that increase inflammation and tissue damage (9).…”

Stereotypic and specific elements of the human colonic response to Entamoeba histolytica and Shigella flexneri

“…Human colonic xenografts were placed into the subscapular region of 6-8 week old SCID mice as previously described (Seydel et al, 1997). Incisions were closed with Michel clips, and grafts were allowed to develop for 10 weeks before use.…”