Entamoeba histolytica cysteine proteases cleave the MUC2 mucin in its C-terminal domain and dissolve the protective colonic mucus gel.

In order for the protozoan parasite Entamoeba histolytica (E.h.) to cause invasive intestinal and extraintestinal infection, which leads to significant morbidity and mortality, it must disrupt the protective mucus layer by a previously unknown mechanism.

Entamoeba histolytica-secreted products degrade colonic mucin oligosaccharides.

Degradation of the mucus layer by Entamoeba histolytica is a prerequisite for invasion of the colonic mucosa. In this study, we demonstrate that amoeba-secreted products degrade (3)H-labeled and native colonic mucin oligosaccharides independently of proteolytic activity. We conclude that E.

Mucin and Toll-like receptors in host defense against intestinal parasites.

Gastrointestinal mucin is a constituent of luminal barrier function and is the first line of host defense against invading pathogens. Mucin carbohydrates and amino acids, as well as trapped soluble host defense molecules, serve as substrates for colonization and control or deter pathogen invasion to the underlying mucosal epithelial cells. Toll-like receptors on the surface of epithelial cells act as sensors for invading pathogens, and the ensuing host response limits parasite invasion and leads to adaptive immunity.

Entamoeba histolytica cysteine proteinases disrupt the polymeric structure of colonic mucin and alter its protective function.

The adherent mucous gel layer lining the colonic epithelium is the first line of host defense against invasive pathogens, such as Entamoeba histolytica. The mucous layer prevents the attachment of amoeba to the colonic epithelium by trapping and aiding in the expulsion of the parasite. Disruption of the mucous layer is thought to occur in invasive amebiasis, and the mechanism by which the parasite overcomes this barrier is not known.