Interaction of LS174T human colon cancer cell mucins with Entamoeba histolytica: an in vitro model for colonic disease.

BACKGROUND & AIMS: Colonic mucins secreted by goblet cells protect the colon by preventing the attachment of enteric pathogens to the epithelium. Entamoeba histolytica overcomes this protective barrier and causes ulcerations, allowing the parasite to disseminate to the liver and form abscesses. An in vitro model is used to study the interaction between E. histolytica and colonic mucins.

METHODS

Secretory mucins from the colonic adenocarcinoma cell line LS174T were collected and their functions assessed by their ability to inhibit amebic adherence to target cells and killing. The cytoprotective effect of mucus against E. histolytica cytolysis of LS174T monolayers was studied at 37 degrees C.

RESULTS

Sepharose 4B column chromatography, metabolic labeling with [3H]glucosamine, cesium chloride density gradient centrifugation, and amino acid and carbohydrate compositional analysis revealed that LS174T cell mucins were typical of native colonic mucins. Mucin O-linked oligosaccharides bound to and inhibited the adherence of amebae to Chinese hamster ovary cells. E. histolytica killing of Chinese hamster ovary cell monolayers occurred rapidly, whereas killing of LS174T monolayers with an intact mucus layer was significantly retarded.

CONCLUSIONS

Our results show that colonic mucins serve as the first line of host defense against amebic invasion and provide a useful model to study pathogen-mucin interactions.