The parasite Entamoeba histolytica exploits the activities of human matrix metalloproteinases to invade colonic tissue.

Intestinal invasion by the protozoan parasite Entamoeba histolytica is characterized by remodelling of the extracellular matrix (ECM). The parasite cysteine proteinase A5 (CP-A5) is thought to cooperate with human matrix metalloproteinases (MMPs) involved in ECM degradation. Here, we investigate the role CP-A5 plays in the regulation of MMPs upon mucosal invasion. We use human colon explants to determine whether CP-A5 activates human MMPs. Inhibition of the MMPs' proteolytic activities abolishes remodelling of the fibrillar collagen structure and prevents trophozoite invasion of the mucosa. In the presence of trophozoites, MMPs-1 and -3 are overexpressed and are associated with fibrillar collagen remodelling. In vitro, CP-A5 performs the catalytic cleavage needed to activate pro-MMP-3, which in turn activates pro-MMP-1. Ex vivo, incubation with recombinant CP-A5 was enough to rescue CP-A5-defective trophozoites. Our results suggest that MMP-3 and/or CP-A5 inhibitors may be of value in further studies aiming to treat intestinal amoebiasis.